JP6663887B2 - Solid-state imaging device, manufacturing method thereof, and electronic device - Google Patents

Description

  The present invention relates to a solid-state imaging device, a method for manufacturing the same, and an electronic apparatus.

  Electronic devices such as digital video cameras and digital still cameras include solid-state imaging devices. For example, the solid-state imaging device includes a CMOS (Complementary Metal Oxide Semiconductor) image sensor and a CCD (Charge Coupled Device) image sensor.

  In a solid-state imaging device, a plurality of pixels are arranged on a surface of a substrate. In each pixel, a photoelectric conversion unit is provided. The photoelectric conversion unit is, for example, a photodiode, and generates signal charges by receiving incident light on a light receiving surface and performing photoelectric conversion.

  In a solid-state imaging device, a CMOS image sensor has pixels configured to include a pixel transistor in addition to a photoelectric conversion unit. The pixel transistor is configured to read out a signal charge generated by the photoelectric conversion unit and output the signal charge to a signal line as an electric signal.

  In a solid-state imaging device, a photoelectric conversion unit generally receives light that enters from a surface side of a substrate on which circuit elements, wiring, and the like are provided. In this case, it may be difficult to improve the sensitivity because light entering the circuit element or the wiring is blocked or reflected.

  For this reason, a “backside illumination type” has been proposed in which a photoelectric conversion unit receives light incident from the backside opposite to the front side of the substrate on which circuit elements, wirings, and the like are provided (for example, Patent Document 1). 4).

  By the way, it is known that the photoelectric conversion unit has a HAD (Hole Accumulation Diode) structure in order to suppress generation of dark current due to an interface state of a semiconductor provided with the photoelectric conversion unit. In the HAD structure, the generation of dark current is suppressed by forming a positive charge accumulation (hole) accumulation region on the light receiving surface of the n-type charge accumulation region.

In order to form this positive charge storage region at the interface of the photoelectric conversion unit, a “film having a negative fixed charge” is provided on the light-receiving surface of the n-type charge storage region, and pilling is performed. It has been proposed to suppress the occurrence of. Here, a high-dielectric film having a high refractive index, such as a hafnium oxide film (HfO ₂ film), is used as a “film having a negative fixed charge” to suppress the generation of dark current and to form the hafnium oxide film. High sensitivity is realized by using it as an anti-reflection film. (See, for example, Patent Documents 5 and 6).

JP 2003-31785 A JP 2005-347707 A JP 2005-353631 A JP 2005-339555 A JP-A-2007-258684 (paragraphs 0163 to 0168) JP 2008-306154 A (paragraph 0044 and the like)

  FIG. 17 is a cross-sectional view illustrating a main part of a pixel P of a “backside illumination” CMOS image sensor.

  As shown in FIG. 17, in the “backside illumination” CMOS image sensor, a photodiode 21 is provided inside a semiconductor layer 101 at a portion partitioned by a pixel separating portion 101 pb.

  Although not shown in FIG. 17, a pixel transistor is provided on the surface (the lower surface in FIG. 17) of the semiconductor layer 101, and as shown in FIG. 17, a wiring layer is formed so as to cover the pixel transistor. 111 are provided. The support substrate SS is provided on the surface of the wiring layer 111.

  On the other hand, on the back surface (the top surface in FIG. 17) of the semiconductor layer 101, an antireflection film 50J, a light shielding film 60J, a color filter CF, and a microlens ML are provided. The photodiode 21 is configured to receive H.

Here, as shown in FIG. 17, the antireflection film 50J covers the back surface (upper surface) of the semiconductor layer 101. The antireflection film 50J is formed of a high dielectric material having a negative fixed charge so that the generation of dark current is suppressed by forming a positive charge accumulation (hole) accumulation region on the light receiving surface JS of the photodiode 21. It is formed using. For example, a hafnium oxide film (HfO ₂ film) is provided as the antireflection film 50J.

  As shown in FIG. 17, the light-shielding film 60J is formed on the upper surface of the antireflection film 50J via the interlayer insulating film SZ. Here, the light-shielding film 60J is provided above the pixel separation portion 101pb provided inside the semiconductor layer 101.

  The upper surface of the light-shielding film 60J is covered with a planarizing film HT, and a color filter CF and a microlens ML are provided on the upper surface of the planarizing film HT. In the color filter CF, for example, filter layers of three primary colors are arranged in a Bayer arrangement for each pixel P.

  In the case of the above-described structure, since the incident light H that has entered one pixel P does not enter the photodiode 21 of the one pixel P but passes below the light shielding film 60J, another adjacent pixel The light may enter the photodiode 21 of the pixel P. That is, when the incident light H is incident on the light receiving surface JS with a large inclination with respect to the direction z perpendicular to the light receiving surface JS, the light of another color is originally received without being incident on the light receiving surface JS immediately below. Incident on the light receiving surface JS of another pixel P. For this reason, so-called “color mixing” may occur, and the color reproducibility of the captured color image may be reduced, and the image quality may be reduced.

  As described above, in the case of the above configuration, it is difficult to improve the image quality of the captured image because a problem such as “color mixing” occurs due to the oblique light leakage.

  Therefore, the present invention provides a solid-state imaging device, a method of manufacturing the same, and an electronic device capable of improving the image quality and the like of a captured image.

  In the solid-state imaging device of the present invention, a plurality of photoelectric conversion units that receive incident light on a light receiving surface are provided with a semiconductor layer provided to correspond to a plurality of pixels, and the incident light is incident on the semiconductor layer. An anti-reflection film provided on the incident surface side for preventing reflection of the incident light, and an opening provided on the incident surface side of the semiconductor layer and passing the incident light to the light receiving surface; A first anti-reflection portion covering the light receiving surface and the portion provided with the light-shielding film on the incident surface, and the light-reflection film on the incident surface. A second anti-reflection portion formed on the first anti-reflection portion so as to cover at least a portion where the light receiving surface is provided, wherein the light-shielding film is formed of the second anti-reflection portion. Not provided on the first anti-reflection portion. It has been kicked.

  Preferably, the thickness of the first anti-reflection portion is smaller than the thickness of the second anti-reflection portion.

  Preferably, the light shielding film is provided so as to protrude in a convex shape on the first anti-reflection portion, and the second anti-reflection portion is provided on a convex side portion of the light shielding film. It is provided to be in contact.

  Preferably, the second antireflection section is formed so as to cover an upper surface of the light shielding film.

  Preferably, there is further provided an intermediate layer provided between the first anti-reflection portion and the light-shielding film, for preventing a reaction between the first anti-reflection portion and the light-shielding film.

  Preferably, the first antireflection portion is formed so as to cover a surface in a trench provided on a side portion of the photoelectric conversion portion in the semiconductor layer, and the light-shielding film is formed of the semiconductor layer. In the layer, the first antireflection portion is provided so as to be embedded in the covered trench.

  Preferably, the first antireflection portion is formed so as to include at least one of hafnium, zirconium, aluminum, tantalum, titanium, yttrium, and an oxide of a lanthanoid element, and stores positive charge on the light receiving surface. It has a negative fixed charge that forms the region.

  Preferably, the antireflection film is formed using a material having a refractive index of 1.5 or more.

  Preferably, the pixel layer is provided on a surface of the semiconductor layer opposite to the incident surface, and outputs a signal charge generated by the photoelectric conversion unit as an electric signal, and the incident surface in the semiconductor layer. And a wiring layer provided so as to cover the pixel transistor on the surface on the side opposite to the above.

  A method for manufacturing a solid-state imaging device according to the present invention includes: a photoelectric conversion unit forming step of forming a plurality of photoelectric conversion units that receive incident light on a light receiving surface in a semiconductor layer so as to correspond to a plurality of pixels; An anti-reflection film forming step of forming an anti-reflection film for preventing reflection on the side of the incident surface on which the incident light is incident on the semiconductor layer; and a light shielding provided with an opening for passing the incident light to the light receiving surface. Forming a film on the side of the semiconductor layer on which the incident light is incident, wherein in the antireflection film forming step, the light receiving surface and the light shielding film are formed on the incident surface. A first anti-reflection portion that covers the surface provided with the first anti-reflection portion, and a second anti-reflection portion that covers the surface on which the light receiving surface is provided on the incident surface on the first anti-reflection portion. Formed as the antireflection film, and in the light shielding film forming step, , The light shielding film is not provided on the second antireflection portion, as provided on the first antireflection portion to form the light shielding film.

  Preferably, in the step of forming an anti-reflection film, the first anti-reflection portion is formed by an ALD method.

  An electronic apparatus according to an aspect of the invention includes a semiconductor layer provided with a plurality of photoelectric conversion units that receive incident light on a light receiving surface corresponding to a plurality of pixels, and an incident surface on which the incident light is incident on the semiconductor layer. And an anti-reflection film that prevents reflection of the incident light, and an opening that is provided on the side of the incident surface in the semiconductor layer and through which the incident light passes to the light receiving surface. A first anti-reflection portion covering the light receiving surface and the portion where the light shielding film is provided on the incident surface, and the light receiving surface on the incident surface. And a second anti-reflection section formed on the first anti-reflection section so as to cover at least the portion provided with, the light-shielding film is disposed on the second anti-reflection section. Not provided, provided on the first anti-reflection portion To have.

  In the present invention, the first antireflection film is provided so as to cover a portion on the back surface of the semiconductor layer where the light receiving surface and the light shielding film are provided. At the same time, a second anti-reflection film is formed on the first anti-reflection film so as to cover the portion where the light receiving surface is provided on the back surface. The light shielding film 60 is provided not on the second anti-reflection film but on the first anti-reflection film.

  ADVANTAGE OF THE INVENTION According to this invention, the solid-state imaging device which can improve the image quality etc. of a picked-up image, its manufacturing method, and an electronic device can be provided.

FIG. 1 is a configuration diagram illustrating a configuration of a camera 40 according to the first embodiment of the present invention. FIG. 2 is a block diagram illustrating an overall configuration of the solid-state imaging device 1 according to the first embodiment of the present invention. FIG. 3 is a diagram illustrating a main part of the solid-state imaging device according to the first embodiment of the present invention. FIG. 4 is a diagram illustrating a main part of the solid-state imaging device according to the first embodiment of the present invention. FIG. 5 is a diagram illustrating a main part of the solid-state imaging device according to the first embodiment of the present invention. FIG. 6 is a diagram illustrating the method of manufacturing the solid-state imaging device according to the first embodiment of the present invention. FIG. 7 is a diagram illustrating the method of manufacturing the solid-state imaging device according to the first embodiment of the present invention. FIG. 8 is a diagram illustrating the method of manufacturing the solid-state imaging device according to the first embodiment of the present invention. FIG. 9 is a diagram illustrating the method for manufacturing the solid-state imaging device according to the first embodiment of the present invention. FIG. 10 is a diagram illustrating the method of manufacturing the solid-state imaging device according to the first embodiment of the present invention. FIG. 11 is a diagram illustrating a main part of a solid-state imaging device 1b according to the second embodiment of the present invention. FIG. 12 is a diagram illustrating the method of manufacturing the solid-state imaging device 1b according to the second embodiment of the present invention. FIG. 13 is a diagram illustrating the method of manufacturing the solid-state imaging device 1b according to the second embodiment of the present invention. FIG. 14 is a diagram illustrating the method of manufacturing the solid-state imaging device 1b according to the second embodiment of the present invention. FIG. 15 is a diagram illustrating a main part of the solid-state imaging device 1c according to the third embodiment of the present invention. FIG. 16 is a diagram illustrating a main part of a solid-state imaging device 1d according to the fourth embodiment of the present invention. FIG. 17 is a cross-sectional view illustrating a main part of a pixel P of a “backside illumination” CMOS image sensor.

  An embodiment of the present invention will be described with reference to the drawings.

The description will be made in the following order.
1. Embodiment 1 (when covering the upper surface of the light shielding film)
2. Embodiment 2 (when covering the upper surface of the light-shielding film and providing an intermediate layer)
3. Embodiment 3 (when the upper surface of the light shielding film is not covered)
4. Embodiment 4 (light-shielding film embedded type)
5. Other

<1. First Embodiment>
(1) Device Configuration (1-1) Main Configuration of Camera FIG. 1 is a configuration diagram showing a configuration of a camera 40 according to the first embodiment of the present invention.

  As shown in FIG. 1, the camera 40 includes the solid-state imaging device 1, an optical system 42, a control unit 43, and a signal processing circuit 44. Each part will be described sequentially.

  The solid-state imaging device 1 generates signal charges by receiving light H incident via the optical system 42 on the imaging surface PS and performing photoelectric conversion. Here, the solid-state imaging device 1 is driven based on a control signal output from the control unit 43, reads out a signal charge, and outputs it as raw data.

  The optical system 42 includes optical members such as an imaging lens and a diaphragm, and is arranged so as to condense the light H by the incident subject image to the imaging surface PS of the solid-state imaging device 1.

  The control unit 43 outputs various control signals to the solid-state imaging device 1 and the signal processing circuit 44, and controls and drives the solid-state imaging device 1 and the signal processing circuit 44.

  The signal processing circuit 44 is configured to generate a digital image of a subject image by performing signal processing on an electric signal output from the solid-state imaging device 1.

(1-2) Main Configuration of Solid-State Imaging Device The overall configuration of the solid-state imaging device 1 will be described.

  FIG. 2 is a block diagram illustrating an overall configuration of the solid-state imaging device 1 according to the first embodiment of the present invention.

  The solid-state imaging device 1 of the present embodiment is a CMOS image sensor, and includes a plate-shaped semiconductor layer 101 as shown in FIG. The semiconductor layer 101 is, for example, a single crystal silicon semiconductor, and has a pixel region PA and a peripheral region SA.

  As shown in FIG. 2, the pixel area PA has a rectangular shape, and a plurality of pixels P are arranged in each of the horizontal direction x and the vertical direction y. That is, the pixels P are arranged in a matrix.

  In the pixel area PA, the pixels P are configured to receive incident light and generate signal charges. Then, the generated signal charge is read out by a pixel transistor (not shown) and output as an electric signal. The detailed configuration of the pixel P will be described later.

  The peripheral area SA is located around the pixel area PA as shown in FIG. In the peripheral area SA, a peripheral circuit is provided.

  Specifically, as shown in FIG. 2, a vertical drive circuit 13, a column circuit 14, a horizontal drive circuit 15, an external output circuit 17, a timing generator (TG) 18, and a shutter drive circuit 19 It is provided as a peripheral circuit.

  As shown in FIG. 2, the vertical drive circuit 13 is provided on the side of the pixel area PA in the peripheral area SA, and is configured to select and drive the pixels P of the pixel area PA in row units. I have.

  As shown in FIG. 2, the column circuit 14 is provided at the lower end of the pixel area PA in the peripheral area SA, and performs signal processing on a signal output from the pixel P in column units. Here, the column circuit 14 includes a CDS (Correlated Double Sampling; correlated double sampling) circuit (not shown), and performs signal processing for removing fixed pattern noise.

  The horizontal drive circuit 15 is electrically connected to the column circuit 14, as shown in FIG. The horizontal drive circuit 15 includes, for example, a shift register, and sequentially outputs signals held for each column of the pixels P in the column circuit 14 to the external output circuit 17.

  The external output circuit 17 is electrically connected to the column circuit 14 as shown in FIG. 2, performs signal processing on a signal output from the column circuit 14, and outputs the signal to the outside. The external output circuit 17 includes an AGC (Automatic Gain Control) circuit 17a and an ADC circuit 17b. In the external output circuit 17, after the AGC circuit 17a applies a gain to the signal, the ADC circuit 17b converts the analog signal into a digital signal and outputs the signal to the outside.

  The timing generator 18 is electrically connected to each of the vertical drive circuit 13, the column circuit 14, the horizontal drive circuit 15, the external output circuit 17, and the shutter drive circuit 19, as shown in FIG. The timing generator 18 generates various timing signals and outputs the signals to the vertical drive circuit 13, the column circuit 14, the horizontal drive circuit 15, the external output circuit 17, and the shutter drive circuit 19, thereby performing drive control for each unit.

  The shutter drive circuit 19 is configured to select the pixels P on a row-by-row basis and adjust the exposure time of the pixels P.

(1-3) Detailed Configuration of Solid-State Imaging Device The details of the solid-state imaging device according to the present embodiment will be described.

  FIG. 3 to FIG. 5 are diagrams illustrating a main part of the solid-state imaging device according to the first embodiment of the present invention.

  FIG. 3 is a cross-sectional view of the pixel P. FIG. 4 is a top view of the pixel P formed on the semiconductor substrate. FIG. 5 shows a circuit configuration of the pixel P. FIG. 3 shows a cross section taken along the line X1-X2 shown in FIG.

  As shown in FIG. 3, the solid-state imaging device 1 includes a photodiode 21 provided inside a semiconductor layer 101. For example, it is provided on a semiconductor substrate thinned to a thickness of about 10 to 20 μm.

  Although not shown in FIG. 3, the pixel transistor Tr shown in FIGS. 4 and 5 is provided on the surface (the lower surface in FIG. 3) of the semiconductor layer 101. As shown in FIG. 3, a wiring layer 111 is provided so as to cover the pixel transistor Tr. In the wiring layer 111, a support substrate SS is provided on a surface opposite to the semiconductor layer 101 side. Is provided.

  On the other hand, on the back surface (the top surface in FIG. 3) of the semiconductor layer 101, an anti-reflection film 50, a light shielding film 60, a color filter CF, and a microlens ML are provided. Is received by the photodiode 21.

  That is, the solid-state imaging device 1 of the present embodiment is a “backside illumination CMOS image sensor”, and the incident light H on the backside (upper surface in FIG. 3) opposite to the front surface (lower surface in FIG. 3). Is formed.

(A) Photodiode 21 In the solid-state imaging device 1, a plurality of photodiodes 21 are arranged so as to correspond to the plurality of pixels P shown in FIG. In other words, on the imaging plane (xy plane), they are provided side by side in the horizontal direction x and in the vertical direction y orthogonal to the horizontal direction x.

  The photodiode 21 is configured to generate and store signal charges by receiving incident light H (subject image) and performing photoelectric conversion.

  Here, as shown in FIG. 3, the photodiode 21 receives incident light that enters from the back surface (the top surface in FIG. 3) of the semiconductor layer 101. As shown in FIG. 3, an antireflection film 50, a flattening film HT, a color filter CF, and a microlens ML are provided above the photodiode 21. The photodiode 21 receives light and performs photoelectric conversion.

  As shown in FIG. 3, the photodiode 21 is provided in a semiconductor layer 101 which is, for example, a single crystal silicon semiconductor. Specifically, the photodiode 21 includes an n-type charge storage region (not shown). At each interface between the upper surface and the lower surface of the n-type charge storage region, a hole storage region (not shown) is formed so as to suppress generation of dark current.

  As shown in FIG. 3, a pixel separation portion 101pb in which a p-type impurity is diffused to electrically separate a plurality of pixels P is provided inside the semiconductor layer 101. The photodiode 21 is provided in a region partitioned by the portion 101pb.

  For example, as shown in FIG. 4, the pixel separating portion 101pb is formed so as to be interposed between the plurality of pixels P. That is, the pixel separating portion 101pb is formed so that the planar shape becomes a lattice shape, and the photodiode 21 is formed in a region partitioned by the pixel separating portion 101pb, as shown in FIG.

  Then, as shown in FIG. 5, the anode of each photodiode 21 is grounded, and the stored signal charges (here, electrons) are read out by the pixel transistors Tr, and are sent to the vertical signal lines 27 as electric signals. It is configured to be output.

(B) Pixel Transistor Tr In the solid-state imaging device 1, a plurality of pixel transistors Tr are arranged so as to correspond to the plurality of pixels P shown in FIG.

  As shown in FIGS. 4 and 5, the pixel transistor Tr includes a transfer transistor 22, an amplification transistor 23, a selection transistor 24, and a reset transistor 25, and reads out a signal charge from the photodiode 21 and outputs it as an electric signal. It is configured. For example, as shown in FIG. 4, the pixel transistor Tr is provided so as to be located below the photodiode 21 on the imaging surface (xy surface).

  Although not shown in FIG. 3, each of the transistors 22 to 25 constituting the pixel transistor Tr is provided on the surface of the semiconductor layer 101 where the wiring layer 111 is provided. For example, each of the transistors 22 to 25 is formed in a pixel separation unit 101 pb that separates pixels P in the semiconductor layer 101. For example, each of transistors 22 to 25 is an N-channel MOS transistor, and each gate is formed using, for example, polysilicon. Each of the transistors 22 to 25 is covered with the wiring layer 111.

  In the pixel transistor Tr, the transfer transistor 22 is configured to transfer the signal charges generated by the photodiode 21 to the floating diffusion FD, as shown in FIGS.

  Specifically, as shown in FIGS. 4 and 5, the transfer transistor 22 is provided between the cathode of the photodiode 21 and the floating diffusion FD. The transfer line 22 is electrically connected to the gate of the transfer transistor 22. In the transfer transistor 22, the signal charge accumulated in the photodiode 21 is transferred to the floating diffusion FD by receiving the transfer signal TG from the transfer line 26 to the gate.

  As shown in FIGS. 4 and 5, in the pixel transistor Tr, the amplifying transistor 23 is configured to amplify and output an electric signal converted from a charge into a voltage in the floating diffusion FD.

  Specifically, the amplification transistor 23 is provided between the selection transistor 24 and the reset transistor 25, as shown in FIG. Here, as shown in FIG. 5, the gate of the amplification transistor 23 is electrically connected to the floating diffusion FD. The amplifying transistor 23 has a drain electrically connected to the power supply line Vdd and a source electrically connected to the selection transistor 24. When the selection transistor 24 is selected to be turned on, the amplification transistor 23 is supplied with a constant current from the constant current source I and operates as a source follower. Therefore, in the amplifying transistor 23, when the selection signal is supplied to the selection transistor 24, the electric signal converted from the charge into the voltage is amplified in the floating diffusion FD.

  In the pixel transistor Tr, the selection transistor 24 is configured to output the electric signal output by the amplification transistor 23 to the vertical signal line 27 when a selection signal is input, as shown in FIGS. Have been.

  Specifically, the selection transistor 24 is provided adjacent to the amplification transistor 23, as shown in FIG. The selection transistor 24 has a gate connected to an address line 28 to which a selection signal is supplied, as shown in FIG. Then, the selection transistor 24 is turned on when the selection signal is supplied, and outputs the output signal amplified by the amplification transistor 23 to the vertical signal line 27 as described above.

  In the pixel transistor Tr, the reset transistor 25 is configured to reset the gate potential of the amplification transistor 23, as shown in FIGS.

  Specifically, the reset transistor 25 is provided so as to be adjacent to the amplification transistor 23, as shown in FIG. As shown in FIG. 5, the gate of the reset transistor 25 is electrically connected to a reset line 29 to which a reset signal is supplied. The drain of the reset transistor 25 is electrically connected to the power supply line Vdd, and the source is electrically connected to the floating diffusion FD. Then, when a reset signal is supplied to the gate from the reset line 29, the reset transistor 25 resets the gate potential of the amplification transistor 23 to the power supply voltage via the floating diffusion FD.

  In the above description, the transfer line 26, the address line 28, and the reset line 29 are wired so as to be connected to the gates of the transistors 22, 24, and 25 of the plurality of pixels P arranged in the horizontal direction H (row direction). Therefore, the operations of the transistors 22, 23, 24, and 25 are simultaneously performed on the pixels P for one row.

(C) Regarding the Wiring Layer 111 In the solid-state imaging device 1, the wiring layer 111 is, as shown in FIG. 3, the back surface (the upper surface in FIG. 3) on which the components such as the antireflection film 50 are provided in the semiconductor layer 101. It is provided on the opposite surface (the lower surface in FIG. 3).

  The wiring layer 111 includes a wiring 111h and an insulating layer 111z, and is formed in the insulating layer 111z so that the wiring 111h is electrically connected to each element. Here, each wiring 111h is formed by being laminated in the insulating layer 111z so as to function as each wiring such as the transfer line 26, the address line 28, the vertical signal line 27, and the reset line 29 shown in FIG. Have been.

  The support substrate SS is provided on the surface of the wiring layer 111 opposite to the side where the semiconductor layer 101 is located. For example, a substrate made of a silicon semiconductor having a thickness of several hundred μm is provided as the support substrate SS.

(D) Anti-Reflection Film 50 In the solid-state imaging device 1, the anti-reflection film 50 has a surface (lower surface in FIG. 3) on the semiconductor layer 101 on which the components such as the wiring layer 111 are provided, as shown in FIG. Are provided on the opposite back surface (the top surface in FIG. 3).

  The anti-reflection film 50 includes a first anti-reflection film 501 and a second anti-reflection film 502 as shown in FIG. It is configured to prevent reflection at That is, the antireflection film 50 is formed by appropriately selecting the material and the film thickness so that the antireflection function is exhibited by the optical interference effect. Here, it is preferable to use a material having a high refractive index. In particular, it is preferable to use a material having a refractive index of 1.5 or more.

  In the antireflection film 50, the first antireflection film 501 is formed so as to cover the back surface (upper surface) of the semiconductor layer 101 as shown in FIG.

  Specifically, as shown in FIG. 3, the first anti-reflection coating is formed on the back surface of the semiconductor layer 101 so as to cover the portion where the photodiode 21 is formed and the portion where the pixel separation portion 101pb is formed. A film 501 is provided. Here, the first antireflection film 501 is provided to have a constant thickness along the flat back surface of the semiconductor layer 101.

  In the present embodiment, the first anti-reflection film 501 is formed to be thinner than the second anti-reflection film 502.

  The first antireflection film 501 has a negative fixed charge so that generation of a dark current is suppressed by forming a positive charge accumulation (hole) accumulation region on the light receiving surface JS of the photodiode 21. It is formed using a high dielectric substance. For example, the first antireflection film 501 is formed so as to include at least one of oxides such as hafnium, zirconium, aluminum, tantalum, titanium, magnesium, yttrium, and lanthanoid elements. By forming the first antireflection film 501 to have negative fixed charges, an electric field is applied to the interface with the photodiode 21 by the negative fixed charges, so that a positive charge storage (hole) storage region is formed. Is done.

For example, a hafnium oxide film (HfO ₂ film) formed to have a thickness of 1 to ₂₀ nm is provided as the first antireflection film 501.

  In the anti-reflection film 50, the second anti-reflection film 502 has a back surface (upper surface) of the semiconductor layer 101 with at least one of the first anti-reflection film 501 and the light shielding film 60 interposed therebetween, as shown in FIG. It is formed so as to cover.

  Specifically, as shown in FIG. 3, at the portion where the photodiode 21 is formed on the back surface of the semiconductor layer 101, the second antireflection film 501 is interposed between the semiconductor layer 101 and the second antireflection film 501. Is provided.

  In the portion where the pixel separation portion 101 pb is formed on the back surface of the semiconductor layer 101, the second reflection layer is formed so that both the first antireflection film 501 and the light shielding film 60 are interposed between the semiconductor layer 101. The prevention film 502 is provided. Here, on the upper surface of the first anti-reflection film 501, a light-shielding film 60 is provided in a portion of the semiconductor layer 101 where the pixel separation portion 101 pb is provided. A second anti-reflection film 502 is provided on the upper surface of one anti-reflection film 501. That is, the convex anti-reflection film 60 is provided on the flat surface of the first anti-reflection film 501 and the uneven surface is provided, and the second anti-reflection film 502 is fixed along the uneven surface. The thickness is provided.

  In the present embodiment, the second anti-reflection film 502 is formed to be thicker than the first anti-reflection film 501.

For example, a hafnium oxide film (HfO ₂ film) formed so as to have a total thickness of 40 to 80 nm in total with the first antireflection film 501 is formed as the second antireflection film 502.

Various materials can be used for the first antireflection film 501 and the second antireflection film 502 in addition to the above-described hafnium oxide film (HfO ₂ film).

Here, it is preferable to form the first anti-reflection film 501 using a material having a higher flat band voltage than a silicon oxide film (SiO ₂ film).

For example, it is preferable to form the first antireflection film 501 using the following high dielectric (High-k) material. In the following, Delta] Vfb is a flat-band voltage Vfb of High-k material (High-k) indicates a value obtained SiO ₂ of the flat band voltage Vfb of (SiO ₂₎ and the difference (i.e., Delta] Vfb = Vfb (High _{-k) -Vfb (SiO 2))} .
・ Al ₂ O ₃ (ΔVfb = 4 to 6 V)
・ HfO ₂ (ΔVfb = 2-3V)
・ ZrO ₂ (ΔVfb = 2-3V)
・ TiO ₂ (ΔVfb = 3-4V)
・ Ta ₂ O ₅ (ΔVfb = 3-4V)
・ MgO ₂ (ΔVfb = 1.5-2.5V)

In addition, it is preferable to form the second antireflection film 502 using the following materials in addition to the above materials.
・ SiN
・ SiON

In the above, the case where the hafnium oxide film (HfO ₂ film) is used for both the first antireflection film 501 and the second antireflection film 502 has been described, but the present invention is not limited to this. Various materials as described above can be used in appropriate combination.

For example, it is preferable to form the first antireflection film 501 and the second antireflection film 502 using a combination of the following materials. In the following, the left side shows a material used for forming the first anti-reflection film 501, and the right side shows a material used for forming the second anti-reflection film 502.
(Material of the first antireflection film 501, material of the second antireflection film 502) =
(HfO ₂ , HfO ₂ )
(HfO ₂ , Ta ₂ O ₅ )
(HfO ₂ , Al ₂ O ₃ )
(HfO ₂ , ZrO ₂ )
(HfO ₂ , TiO ₂ )
(MgO ₂ , HfO ₂ )
(Al ₂ O ₃ , SiN)
(HfO ₂ , SiON)

(E) Light-Shielding Film 60 In the solid-state imaging device 1, the light-shielding film 60 is provided on the back surface (the upper surface in FIG. 3) of the semiconductor layer 101 as shown in FIG.

  The light shielding film 60 is configured to shield a part of the incident light H traveling from above the semiconductor layer 101 to the back surface of the semiconductor layer 101.

  As shown in FIG. 3, the light-shielding film 60 is provided above the pixel separating portion 101pb provided inside the semiconductor layer 101. On the other hand, above the photodiode 21 provided inside the semiconductor layer 101, the light-shielding film 60 is not provided but is open so that the incident light H enters the photodiode 21. .

  That is, although not shown in FIG. 4, the light-shielding film 60 is formed so that the planar shape becomes a lattice shape, similarly to the pixel separating portion 101pb.

  In the present embodiment, as shown in FIG. 3, the light shielding film 60 is provided on the upper surface of the first antireflection film 501 so as to protrude in a convex shape. The light-shielding film 60 is provided such that the upper surface is covered with the second anti-reflection film 502 and the convex side portion is in contact with the second anti-reflection film 502.

  The light shielding film 60 is formed of a light shielding material that blocks light. For example, a tungsten (W) film formed to have a thickness of 100 to 400 nm is formed as the light shielding film 60. In addition, it is also preferable to form the light shielding film 60 by laminating a titanium nitride (TiN) film and a tungsten (W) film.

(F) Others In addition, as shown in FIG. 3, on the back surface side of the semiconductor layer 101, a flattening film HT is provided on the upper surface of the antireflection film 50. The color filter CF and the microlens ML are provided on the upper surface of the flattening film HT.

  The color filter CF includes, for example, a red filter layer (not shown), a green filter layer (not shown), and a blue filter layer (not shown), and each filter layer of the three primary colors is provided in each pixel P in a Bayer arrangement. It is arranged to correspond. That is, the color filter CF is configured such that light of different colors is transmitted between the pixels P adjacent to each other in the horizontal direction x and the hydraulic direction y.

  A plurality of micro lenses ML are arranged so as to correspond to each pixel P. The micro lens ML is a convex lens that protrudes in a convex shape on the back surface side of the semiconductor layer 101, and is configured to collect incident light H to the photodiode 21 of each pixel P. For example, the micro lens ML is formed using an organic material such as a resin.

(2) Manufacturing Method A main part of a manufacturing method of manufacturing the solid-state imaging device 1 will be described.

  6 to 10 are diagrams illustrating a method of manufacturing a solid-state imaging device according to the first embodiment of the present invention.

  FIGS. 6 to 10 show cross sections, as in FIG. 3, and the solid-state imaging device 1 shown in FIG.

(2-1) Formation of Photodiode 21, etc. First, as shown in FIG. 6, the formation of the photodiode 21 and the like are performed.

  Here, the photodiode 21 and the pixel separation portion 101pb are formed by ion-implanting impurities from the surface of a semiconductor substrate formed of a single crystal silicon semiconductor. Then, after forming a pixel transistor Tr (not shown in FIG. 6) on the surface of the semiconductor substrate, a wiring layer 111 is formed so as to cover the pixel transistor Tr. Then, the support substrate SS is attached to the surface of the wiring layer 111.

  Thereafter, the semiconductor substrate 101 is formed by thinning the semiconductor substrate so as to have a thickness of, for example, about 10 to 20 μm. For example, thinning is performed by polishing by a CMP method.

(2-2) Formation of First Anti-Reflection Film 501 Next, as shown in FIG. 7, a first anti-reflection film 501 is formed.

  Here, as shown in FIG. 7, the first antireflection film 501 is formed so as to cover the back surface (upper surface) of the semiconductor layer 101.

  Specifically, as shown in FIG. 3, the first anti-reflection coating is formed on the back surface of the semiconductor layer 101 so as to cover the portion where the photodiode 21 is formed and the portion where the pixel separation portion 101pb is formed. A film 501 is provided.

For example, a hafnium oxide film (HfO ₂ film) is formed by an ALD (Atomic Layer Deposition) method at a film formation temperature of 200 to 300 ° C. so as to have a film thickness of 1 to ₂₀ nm. One anti-reflection film 501 is provided.

(2-3) Formation of Light Shielding Film 60 Next, as shown in FIG. 8, the light shielding film 60 is formed.

  Here, as shown in FIG. 8, the light-shielding film 60 is formed on the upper surface of the first antireflection film 501 so as to be located above the pixel separation portion 101pb provided inside the semiconductor layer 101.

  For example, a tungsten (W) film (not shown) is formed on the upper surface of the first antireflection film 501 by a sputtering method so as to have a thickness of 100 to 400 nm, and then the tungsten film is patterned. Then, the light shielding film 60 is formed. Specifically, the light-shielding film 60 is formed from a tungsten film by performing a dry etching process.

(2-4) Formation of Second Anti-Reflection Film 502 Next, as shown in FIG. 9, a second anti-reflection film 502 is formed.

  Here, as shown in FIG. 9, the second anti-reflection film 502 covers the back surface (upper surface) of the semiconductor layer 101 with at least one of the first anti-reflection film 501 and the light shielding film 60 interposed therebetween. Next, a second anti-reflection film 502 is formed.

  Specifically, as shown in FIG. 9, only the first anti-reflection film 501 is interposed in the portion where the photodiode 21 is formed, and the first anti-reflection film 501 and the light-shielding portion are formed in the portion where the pixel separation portion 101pb is formed. A second anti-reflection film 502 is formed so that both the film 60 and the film 60 are interposed.

For example, a hafnium oxide film (HfO ₂ film) is formed by a physical vapor deposition (PVD) method so that the total thickness of the first antireflection film 501 and the first anti-reflection film 501 is 40 to 80 nm. An anti-reflection film 502 is formed. The film formation rate by the PVD method is higher than that of the ALD method, so that a thick film can be formed in a short time.

(2-5) Formation of Flattening Film HT Next, as shown in FIG. 10, a flattening film HT is formed.

  Here, as shown in FIG. 10, a flattening film HT is formed over the second antireflection film 502 so that the upper surface becomes flat.

  For example, the flattening film HT is formed by applying an organic material such as a resin by a spin coating method.

  Thereafter, as shown in FIG. 3, a color filter CF and a microlens ML are provided on the back surface side of the semiconductor layer 101. In this manner, a backside illumination CMOS image sensor is completed.

(3) Conclusion As described above, in the present embodiment, the plurality of photodiodes 21 that receive the incident light H on the light receiving surface JS are provided inside the semiconductor layer 101 so as to correspond to the plurality of pixels P. I have. An anti-reflection film 50 for preventing reflection of the incident light H is provided on the back surface (upper surface) of the semiconductor layer 101 on which the incident light H is incident. Further, on the back surface side of the semiconductor layer 101, there is provided a light shielding film 60 in which an opening through which the incident light H passes to the light receiving surface JS is formed.

  Here, the anti-reflection film 50 includes a plurality of films of a first anti-reflection film 501 and a second anti-reflection film 502, and the first anti-reflection film 501 has a light-receiving surface JS and a light-shielding film Is provided so as to cover the portion provided with. At the same time, in the anti-reflection film 50, the second anti-reflection film 502 is formed on the first anti-reflection film 501 so as to cover the portion on the back surface where the light receiving surface JS is provided. The thickness of the first anti-reflection film 501 is smaller than that of the second anti-reflection film 502. The light-shielding film 60 is not provided on the second anti-reflection film 502 but is provided on the first anti-reflection film 501 (see FIG. 3).

  As described above, in the present embodiment, only the thin first anti-reflection film 501 is formed between the semiconductor layer 101 and the light shielding film 60. Therefore, it is possible to prevent the incident light H from transmitting below the light-shielding film 60, and thus prevent the incident light H that has entered the pixel P from entering the photodiode 21 of another adjacent pixel P. it can. That is, it is possible to prevent the incident light H from being incident on the light receiving surface JS immediately below and from being incident on the light receiving surface JS of another pixel P that receives light of another color.

  Therefore, in the present embodiment, it is possible to prevent “color mixture” from occurring and to improve color reproducibility in a captured color image.

  Therefore, the present embodiment can improve image quality.

  In the present embodiment, the first anti-reflection film 501 is formed using a high dielectric having a negative fixed charge. For this reason, a positive charge accumulation (hole) accumulation region is formed on the light receiving surface JS of the photodiode 21, so that generation of dark current can be suppressed.

In this embodiment, the antireflection film 50 is formed using a material having a refractive index of 1.5 or more. For this reason, the difference in the refractive index from silicon (Si) is reduced, so that the effect of preventing reflection of the silicon on the light receiving surface can be obtained. In particular, it is preferable to use a material having an intermediate refractive index between the lower layer Si (3.6) and the upper layer SiO ₂ (1.45). Specifically, it is preferable to form the SiN film (having a refractive index of about 2) and the antireflection film 50. In addition, a high refractive index film such as TiO ₂ (refractive index of about 2.5) may be used. Therefore, it is preferable to form the antireflection film 50 using a material having a refractive index of 1.5 or more and 2.6 or less.
In this embodiment, the first antireflection film 501 is formed by the ALD method. For this reason, a good silicon interface with few interface states can be formed, and the effect of dark current reduction can be obtained.

<2. Embodiment 2>
(1) Device Configuration, etc. FIG. 11 is a diagram illustrating a main part of a solid-state imaging device 1b according to the second embodiment of the present invention.

  FIG. 11 shows a cross section of the pixel P, similarly to FIG.

  As shown in FIG. 11, in the present embodiment, an insulating film Z1 is provided. At the same time, the material of the light shielding film 60b is different from that of the first embodiment. Except for these points, the present embodiment is the same as the first embodiment. Therefore, the description of the overlapping portions will be omitted.

  In the present embodiment, unlike the first embodiment, the light shielding film 60b is formed using a titanium (Ti) film.

  Titanium films have excellent adhesion. However, the titanium film has a strong reducing action.

When a titanium film is directly formed as the light shielding film 60b on the hafnium oxide film (HfO ₂ film) formed as the first anti-reflection film 501, a reaction occurs between the two films. For this reason, in this case, it may be difficult to effectively suppress the generation of the dark current due to the interface state.

In order to prevent such a problem from occurring, in the present embodiment, as shown in FIG. 11, a hafnium oxide film (HfO ₂ film) formed as a first antireflection film 501 and a light shielding film 60b are formed. An insulating film Z1 is provided as an intermediate layer between the formed titanium film.

  That is, in the present embodiment, the insulating film Z1 is formed using a material that does not easily react with the first antireflection film 501 than the light-shielding film 60b.

  For example, the insulating film Z1 is a silicon oxide film, and is formed to have a thickness of 10 nm to 50 nm.

(2) Manufacturing Method A main part of a manufacturing method for manufacturing the solid-state imaging device will be described.

  12 to 14 are diagrams illustrating a method of manufacturing the solid-state imaging device 1b according to the second embodiment of the present invention.

  FIGS. 12 to 14 show cross sections in the same manner as FIG. 11, and the solid-state imaging device shown in FIG. 11 is manufactured through the respective steps shown in FIGS.

  Also in the case of the present embodiment, the formation of the photodiode 21 and the like and the formation of the first antireflection film 501 are performed as shown in FIGS.

(2-1) Formation of Insulating Film Z1 and Light-Shielding Film 60b Next, as shown in FIG. 12, the insulating film Z1 and the light-shielding film 60b are formed.

  Here, as shown in FIG. 12, the insulating film Z1 and the light shielding film 60 are formed on the upper surface of the first anti-reflection film 501 so as to be located above the pixel separation portion 101pb provided inside the semiconductor layer 101. To form

  For example, a silicon oxide film is formed on the upper surface of the first antireflection film 501 by a plasma CVD method so that the film thickness becomes 10 nm to 50 nm. Thereafter, a titanium (Ti) film is formed as an adhesion layer on the upper surface of the silicon oxide film by, for example, a sputtering method so that the film thickness becomes 10 to 50 nm. Thereafter, a tungsten (W) film is formed as a light-shielding film so as to have a thickness of 100 to 400 nm.

  Then, the insulating film Z1 and the light shielding film 60b are formed by patterning each of the silicon oxide film and the tungsten / titanium film. Specifically, the silicon oxide film is subjected to dry etching to pattern the insulating film Z1. Further, by performing dry etching on the tungsten / titanium film, pattern processing is performed on the light shielding film 60b.

(2-2) Formation of Second Anti-Reflection Film 502 Next, as shown in FIG. 13, a second anti-reflection film 502 is formed.

  Here, as shown in FIG. 13, the second anti-reflection film 502 is formed so as to cover the upper surface of the first anti-reflection film 501 on which the insulating film Z1 and the light shielding film 60b are formed.

For example, as in the case of Embodiment 1, the second anti-reflection film 502 is formed by forming a hafnium oxide film (HfO ₂ film) by a physical vapor deposition (PVD) method.

  Accordingly, only the first anti-reflection film 501 is interposed in the portion where the photodiode 21 is formed, and the first anti-reflection film 501, the insulating film Z1, and the light-shielding film 60b are interposed in the portion where the pixel separation portion 101pb is formed. As a result, a second anti-reflection film 502 is formed.

(2-3) Formation of Flattening Film HT Next, as shown in FIG. 14, a flattening film HT is formed.

  Here, as shown in FIG. 14, as in the case of the first embodiment, a flattening film HT is formed on the second antireflection film 502 so that the upper surface becomes flat.

  Thereafter, as shown in FIG. 11, a color filter CF and a microlens ML are provided on the back surface side of the semiconductor layer 101. In this manner, a backside illumination CMOS image sensor is completed.

(3) Summary

  In this embodiment, only the thin first anti-reflection film 501 is formed between the semiconductor layer 101 and the light-shielding film 60b as in the case of the first embodiment (see FIG. 11).

Therefore, it is possible to prevent “color mixture” from occurring and to improve color reproducibility in a captured color image.
Further, in the present embodiment, unlike the first embodiment, an insulating film Z1 is provided between the first antireflection film 501 and the light shielding film 60b (see FIG. 11).

  For this reason, in the present embodiment, a reaction between the first antireflection film 501 and the light shielding film 60b is prevented. Therefore, even when a material such as titanium having a strong reducing action is used for the light-shielding film 60b in order to improve the adhesion, the effect of the negative fixed charges included in the first antireflection film 501 causes the interface state to be reduced. Generation of the resulting dark current can be effectively suppressed.

  Therefore, the present embodiment can improve image quality.

In addition, in addition to the above, when the first antireflection film 501 and the light-shielding film 60b are formed by a combination of the following materials, the insulating film Z1 may be provided as an intermediate layer as in the present embodiment. It is suitable.
(Material of the first antireflection film 501 and material of the light shielding film 60b) =
(HfO ₂ , Ti), (Al ₂ O ₃ , Ti), (ZrO ₂ , Ti)

<3. Third Embodiment>
(1) Device Configuration, etc. FIG. 15 is a diagram illustrating a main part of a solid-state imaging device 1c according to the third embodiment of the present invention.

  FIG. 15 shows a cross section of the pixel P, similarly to FIG.

  As shown in FIG. 15, in the present embodiment, the configurations of the antireflection film 50c and the light shielding film 60c are different from those of the first embodiment. Except for this point, the present embodiment is the same as the first embodiment. Therefore, the description of the overlapping portions will be omitted.

(A) Regarding anti-reflection film 50c As shown in FIG. 15, the anti-reflection film 50c is composed of a plurality of first and second anti-reflection films 501 and 502c as in the first embodiment. Including.

  In the antireflection film 50c, the first antireflection film 501 is provided on the back surface (the upper surface in FIG. 15) of the semiconductor layer 101, as in the first embodiment. Then, as shown in FIG. 15, the second anti-reflection film 502c is provided on the back surface of the semiconductor layer 101 so that the first anti-reflection film 501 is interposed at the portion where the photodiode 21 is formed. I have.

  However, unlike the first embodiment, the second anti-reflection film 502c is not provided on the back surface of the semiconductor layer 101 where the pixel separation portion 101pb is formed.

(B) Light-Shielding Film 60c As shown in FIG. 15, the light-shielding film 60c has a pixel isolation portion 101pb provided on the semiconductor layer 101 on the upper surface of the first anti-reflection film 501, as in the first embodiment. It is formed in the part. However, the second antireflection film 502c is not provided so as to cover the light shielding film 60c.

(C) Others (manufacturing method, etc.)
In this embodiment, after forming the first antireflection film 501 and before forming the light shielding film 60c, the second antireflection film 502c is formed. Here, after a material film for forming the second anti-reflection film 502c is formed on the upper surface of the first anti-reflection film 501, the material film is patterned to form the second anti-reflection film. Form 502c. That is, the material film for forming the second anti-reflection film 502c is etched so that the surface of the upper surface of the first anti-reflection film 501 where the light shielding film 60c is formed is exposed, and the trench TR is etched. Is formed to form the second antireflection film 502c.

  Next, a material film for forming the light shielding film 60c is formed on the second antireflection film 502c so as to fill the inside of the trench TR. Then, the light shielding film 60c is formed by performing a flattening process so that the upper surface of the second antireflection film 502c is exposed.

  The components are formed as described above to complete the solid-state imaging device 1c.

  In this embodiment, since each part is formed as described above, the first antireflection film 501 and the second antireflection film 502c are formed of a material having a large etching selectivity between them. Is preferred. Further, the light-shielding film 60c is preferably formed of a material that can be easily embedded in the trench TR.

(2) Conclusion In the present embodiment, as in the case of the first embodiment, only the thin first anti-reflection film 501 is formed between the semiconductor layer 101 and the light shielding film 60c (see FIG. 15). .

  Therefore, it is possible to prevent “color mixture” from occurring and to improve color reproducibility in a captured color image.

  In the present embodiment, unlike the first embodiment, the second antireflection film 502 is not formed so as to cover the upper surface of the light shielding film 60c. The light-shielding film 60c is formed so as to be embedded in the trench TR provided in the second anti-reflection film 502 (see FIG. 15).

  Therefore, in the present embodiment, the surfaces of the light shielding film 60c and the second antireflection film 502 are flat (see FIG. 15). Therefore, the planarization film HT stacked thereover can be made thinner and the intensity of the light H incident on the light receiving surface JS can be improved, so that higher sensitivity can be realized.

  Therefore, in the present embodiment, the image quality can be improved.

<4. Embodiment 4>
(1) Device Configuration, etc. FIG. 16 is a diagram illustrating a main part of a solid-state imaging device 1d according to the fourth embodiment of the present invention.

  FIG. 16 shows a cross section of the pixel P, similarly to FIG.

  As shown in FIG. 16, in the present embodiment, the configurations of the antireflection film 50d and the light shielding film 60d are different from those of the first embodiment. Except for this point, the present embodiment is the same as the first embodiment. Therefore, the description of the overlapping portions will be omitted.

(A) Regarding anti-reflection film 50d As shown in FIG. 16, the anti-reflection film 50d includes a plurality of first and second anti-reflection films 501d and 502d as in the first embodiment. Including.

  In the antireflection film 50d, the first antireflection film 501d is formed so as to cover the back surface (upper surface) side of the semiconductor layer 101, as in the first embodiment, as shown in FIG. That is, the first antireflection film 501d is provided on the back surface side of the semiconductor layer 101 so as to cover the portion where the photodiode 21 is formed and the portion where the pixel separation portion 101pb is formed.

  However, in the present embodiment, unlike the first embodiment, the back surface side of the semiconductor layer 101 is not flat, but is provided with a trench TRd and has an uneven surface, and the first antireflection film 501d has the uneven surface. Is formed to have a constant thickness so as to cover.

  In the antireflection film 50d, as shown in FIG. 16, the second antireflection film 502d has a back surface (upper surface) of the semiconductor layer 101 with at least one of the first antireflection film 501d and the light shielding film 60d interposed therebetween. It is formed so as to cover.

  Specifically, as shown in FIG. 16, in the portion where the photodiode 21 is formed on the back surface of the semiconductor layer 101, the first antireflection film 501 d is placed between the semiconductor layer 101 and the semiconductor layer 101 as in the first embodiment. A second antireflection film 502d is provided so as to be interposed.

  In the portion where the pixel separation portion 101pb is formed on the back surface of the semiconductor layer 101, the second reflection layer 501d and the light-shielding film 60d are so formed that the second reflection layer 501d and the light-shielding film 60d are interposed between the semiconductor layer 101. The prevention film 502 is provided.

  In the present embodiment, as shown in FIG. 16, unlike the first embodiment, a groove TRd is provided on the back surface side of the semiconductor layer 101, and the first antireflection film 501d covers the surface of the groove TRd. A light shielding film 60d is provided inside the trench TRd. Therefore, a second anti-reflection film 502d is provided on the upper surface of the first anti-reflection film 501d so as to interpose the light-shielding film 60d thus formed. That is, the second anti-reflection film 502d is provided with a constant thickness along the flat surface on which the first anti-reflection film 501d and the light shielding film 60d are provided.

(B) About the light-shielding film 60d The light-shielding film 60d is provided above the pixel separating portion 101pb provided inside the semiconductor layer 101, as shown in FIG.

  In the present embodiment, as shown in FIG. 16, a trench TRd is provided in a portion where the pixel separating portion 101pb is provided on the back surface side of the semiconductor layer 101, and the trench TRd is provided so as to cover the surface of the trench TRd. , A first anti-reflection film 501d. The light-shielding film 60d is provided so as to be embedded in the trench TRd covered with the first anti-reflection film 501d.

  The upper surface of the light shielding film 60d is covered with the second antireflection film 502d.

(C) Others (manufacturing method, etc.)
In the present embodiment, before the first anti-reflection film 501 is formed, a trench TRd is formed on the back surface side of the semiconductor layer 101 in a portion where the pixel separation portion 101pb is provided. Then, a first antireflection film 501 is formed on the back surface of the semiconductor layer 101 so as to cover the trench TRd.

  Next, a material film for forming the light shielding film 60d is formed on the first antireflection film 501d so as to fill the inside of the trench TR. Then, a flattening process is performed so that the upper surface of the first anti-reflection film 501d is exposed, thereby forming the light-shielding film 60d.

  Then, a second anti-reflection film 502d is formed so as to cover the first anti-reflection film 501d and the light shielding film 60d.

  The components are formed as described above to complete the solid-state imaging device 1d.

(2) Conclusion In the present embodiment, the light-shielding film 60d is provided inside the trench TRd provided in the portion where the pixel separation portion 101pb is formed (see FIG. 16).

  For this reason, it is possible for the light-shielding film 60d to block light incident on the photodiode 21 of another pixel P adjacent to the pixel P. Therefore, it is possible to prevent “color mixture” from occurring and to improve color reproducibility in a captured color image.

  Further, in the present embodiment, since the surface of the semiconductor layer 101 is flat, it is possible to reduce the thickness of the flattening film HT laminated thereon, and to reduce the intensity of the light H incident on the light receiving surface JS. Can be improved. Therefore, high sensitivity can be realized.

<5. Others>
When implementing the present invention, the present invention is not limited to the above-described embodiment, and various modifications can be adopted.

  For example, in the above embodiment, the case where the anti-reflection film 50 is configured by two films has been described, but the present invention is not limited to this. Among the surfaces on which the incident light is incident, a first antireflection portion covering the light receiving surface and the portion where the light shielding film is formed, and a second antireflection portion covering the portion where the light receiving surface JS is formed on the first antireflection portion. The number of films is not limited as long as the antireflection film 50 includes the antireflection portions.

  In the above embodiment, the case of the “backside illumination type” has been described, but the present invention is not limited to this. The present invention may be applied to the case of “surface irradiation type”.

  In the above-described embodiment, the case where four types of the transfer transistor, the amplification transistor, the selection transistor, and the reset transistor are provided as the pixel transistors has been described. However, the invention is not limited thereto. For example, the present invention may be applied to a case where three types of transfer transistors, amplification transistors, and reset transistors are provided as pixel transistors.

  In the above embodiment, the case where one transfer transistor, one amplification transistor, one selection transistor, and one reset transistor are provided for one photodiode has been described, but the present invention is not limited to this. For example, the present invention may be applied to a case where one amplification transistor, one selection transistor, and one reset transistor are provided for a plurality of photodiodes.

  Further, in the above embodiment, the case where the present invention is applied to the camera has been described, but the present invention is not limited to this. The present invention may be applied to other electronic devices including a solid-state imaging device, such as a scanner and a copier.

In the above embodiment, the solid-state imaging devices 1, 1b, 1c, and 1d correspond to the solid-state imaging device of the present invention. In the above embodiment, the photodiode 21 corresponds to the photoelectric conversion unit of the present invention. Further, in the above embodiment, the camera 40 corresponds to the electronic device of the present invention. Further, in the above embodiment, the semiconductor layer 101 corresponds to the semiconductor layer of the present invention. In the above embodiment, the antireflection films 50, 50c, and 50d correspond to the antireflection films of the present invention. In the above embodiments, the first anti-reflection films 501 and 501d correspond to a first anti-reflection unit of the present invention. In the above embodiment, the second antireflection films 502, 502c, and 502d correspond to the second antireflection section of the present invention.
In the above embodiment, the light shielding films 60, 60b, 60c, and 60d correspond to the light shielding film of the present invention. Further, in the above embodiment, the light receiving surface JS corresponds to the light receiving surface of the present invention. Further, in the above embodiment, the pixel P corresponds to the pixel of the present invention. Further, in the above embodiment, the insulating layer Z1 corresponds to the intermediate layer of the present invention.

1, 1b, 1c, 1d: solid-state imaging device, 13: vertical drive circuit, 14: column circuit, 15: horizontal drive circuit, 17: external output circuit, 17a: AGC circuit, 17b: ADC circuit, 18: timing generator, 19: shutter drive circuit, 21: photodiode, 22: transfer transistor, 23: amplification transistor, 24: selection transistor, 25: reset transistor, 26: transfer line, 27: vertical signal line, 28: address line, 29: reset Line, 40: camera, 42: optical system, 43: control unit, 44: signal processing circuit, 50, 50c, 50d: anti-reflection film, 501, 501d: first anti-reflection film, 502, 502c, 502d: 2, an anti-reflection film, 60, 60b, 60c, 60d: a light-shielding film, 101: a semiconductor layer, 101pb: a pixel separation portion, 111 Wiring layer, 111h: Wiring, 111z: Insulating layer, CF: Color filter, FD: Floating diffusion, HT: Flattening film, JS: Light receiving surface, P: Pixel, PA: Pixel region, SA: Peripheral region, SS: Support substrate, SZ: interlayer insulating film, TR, TRd: groove, Tr: pixel transistor, Z1: insulating layer

Claims (22)

An image device comprising a semiconductor layer having a first side as an incident light side and a second side opposed to the first side,
The semiconductor layer has a light receiving surface that receives incident light, and a plurality of photoelectric conversion elements that convert light incident on the light receiving surface into electricity.
Each photoelectric conversion element is separated by a pixel separation unit,
The imaging device is
A first antireflection film made of a high dielectric substance having a negative fixed charge, which is provided in contact with the light receiving surface, and is disposed so as to cover a portion where the photoelectric conversion element and the pixel separation portion are formed;
A second antireflection film made of nitride or a high dielectric substance having a negative fixed charge, which is laminated on the light receiving surface in contact with the first antireflection film;
At a position corresponding to the pixel separating portion, a light-shielding film disposed so as to be formed in a convex shape between the first antireflection film and the second antireflection film;
And a wiring layer disposed near the second side of the semiconductor layer.
The light-shielding film is disposed in a convex shape so as to extend from the light incident side to the inside of the pixel separation portion at a position corresponding to the pixel separation portion,
The refractive index of the antireflection film formed by stacking the first antireflection film and the second antireflection film has a small difference from the refractive index of the semiconductor layer, that is, 1.5 to 2.6. Is the following,
Imaging device. The thickness of the first anti-reflection film located below the light-shielding film when viewed from the first side is smaller than the thickness of the second anti-reflection film, and the first anti-reflection film is formed of the light-shielding film. To prevent light from being incident on the photoelectric conversion element of another adjacent pixel that passes below the
The image device according to claim 1. The second anti-reflection film is provided so as to cover the first anti-reflection film and the light-shielding film in a region of the pixel separation unit.
The image device according to claim 1.
In the pixel separating section, an insulating film formed of a material that is less likely to react with the first anti-reflection film than the light-shielding film is provided between the first anti-reflection film and the light-shielding film. Provided,
The image device according to claim 3. The image device includes a trench (groove) provided in the pixel separation unit,
The light shielding film is disposed inside the trench,
The image device according to claim 1. The first antireflection film includes at least one of hafnium, zirconium, aluminum, tantalum, titanium, magnesium, yttrium, and an oxide of a lanthanoid element.
The image device according to claim 1. The second antireflection film includes at least one of a nitride or an oxide of an element of hafnium, zirconium, aluminum, tantalum, titanium, magnesium, yttrium, and a lanthanoid.
The image device according to claim 1. The thickness of the antireflection film in which the first antireflection film and the second antireflection film are stacked is 40 to 80 nm.
The image device according to claim 1.   The image device according to claim 6, wherein a thickness of the first antireflection film formed of hafnium oxide is 1 to 20 nm. The refractive index of the first antireflection film is 1.5 or more;
Image apparatus according to any one of claims 1-9. The refractive index of the second antireflection film is 1.5 or more;
Image apparatus according to any one of claims 1-10. The image device includes a plurality of transistors disposed near the second side of the semiconductor layer.
Image apparatus according to any one of claims 1 to 11. The plurality of transistors include a transfer transistor that transfers charge from the photoelectric conversion element to a floating diffusion unit,
The image device according to claim 12 . The plurality of transistors include an amplification transistor having a gate terminal connected to the floating diffusion unit from the photoelectric conversion element,
The image device according to claim 12 . The plurality of transistors include an amplification transistor having a gate terminal connected to the floating diffusion,
The image device according to claim 12 . The plurality of transistors include a reset transistor having a first terminal connected to the floating diffusion and a second terminal connected to a predetermined power supply.
The image device according to claim 12 . The plurality of transistors include a select transistor operatively connected to a signal line,
The image device according to claim 12 . The signal line is electrically connected to a column circuit including at least a CDS circuit and an ADC circuit;
The image device according to claim 17 . The light shielding film contains tungsten or titanium nitride,
Image apparatus according to any one of claims 1 to 18. The material of the first antireflection film is hafnium oxide,
Image apparatus according to any one of claims 1 to 19, wherein said light-shielding film containing titanium. A microlens is disposed near the first side of the semiconductor layer;
A color filter is disposed between the microlens and the first side of the semiconductor layer;
Image apparatus according to any one of claims 1 to 20. FIG. The wiring layer is disposed between the second side of the semiconductor layer and a support substrate;
Image apparatus according to any one of claims 1 to 21.

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