JP5211541B2 - Manufacturing method of bonded substrate and manufacturing method of semiconductor device - Google Patents

Description

The present invention is, for example, a light-emitting diode is used as a substrate for manufacturing a semiconductor device such as a device, a method of manufacturing a bonding substrate to a process for the preparation of and semiconductors devices.

New substrates obtained by bonding substrates (also called wafers) on which a film is deposited on a substrate are bonded semiconductor substrates or bonded wafers, and semiconductor devices represented by SOI (Silicon On Insulator) It is used as a substrate for
Conventionally, for example, silicon substrates or silicon substrates in which a layer made of a material different from silicon is provided on at least one surface, or a silicon substrate and a glass substrate are bonded together (joining over almost the entire surface). The direct bonding method and the anodic bonding method are used. Or the adhesive agent etc. which join using the hardening phenomenon by a heating or a chemical reaction are also used. In any bonding method, bubbles and voids remain at the bonding interface.
For example, Patent Document 1 and Patent Document 2 propose a bonding method for reducing such bubbles and voids. In any of these methods, a mechanical pressing force is applied between the wafers to be bonded together so that the surfaces of both wafers are adsorbed to each other and bonded.

Japanese Patent No. 3720515 Japanese Patent No. 3321882

  In the conventional bonding methods such as Patent Documents 1 and 2, if the wafers are completely flat, the suction force between the wafers is uniform over the entire surface, and therefore the two wafers are bonded evenly.

However, in actuality, each wafer has its own subtle warp and distortion, so the adsorption force is not uniform across the entire wafer surface simply by mechanically bonding them together. As a result, there is a risk that bubbles and voids may be formed in a portion where the adsorption force is weak. Even if bubbles and voids are not generated, uneven pressure applied during bonding may appear as a difference in the properties of the final product.
Further, in the conventional bonding method, the wafer is bonded by mechanically applying a pressing force. However, when such a mechanical pressing force is applied, the material mechanical deflection or Strain or residual stress is likely to occur, and as a result, cracks and dislocations may occur in the portion where the stress is concentrated, leading to a decrease in reliability and serious damage.

The present invention has been made in view of such a problem, and its purpose is to solve the problem that the bonding substrate is deteriorated in reliability or damaged due to the manufacturing process of the bonding substrate. Te is to provide a method of manufacturing a semiconductor device manufactured using a method of manufacturing a bonding substrate that can manufacture a highly reliable laminated substrate with high yield, the bonding substrate Oyo benefactor.

The manufacturing method of the 1st bonding board | substrate of this invention superimposes two or more board | substrates, accommodates in the sealing container which has flexibility, and depressurizes and seals the inside of the said sealing container. Storing the sealing container in which the stacked substrates are sealed in a pressurized container, pressurizing the pressurizing fluid in the pressurized container to a pressure exceeding atmospheric pressure, and the inside of the pressurized container. And a step of heating to 50 ° C. or higher.
The manufacturing method of the 2nd bonding substrate of this invention WHEREIN: The manufacturing method of the said 1st bonding substrate WHEREIN: The pressure in the said container for sealing in the process of decompressing and sealing the inside of the said container for sealing is 1.1. It is characterized by reducing the pressure below the atmospheric pressure.
The manufacturing method of the 3rd bonding board | substrate of this invention is a manufacturing method of the said 1st or 2nd bonding board | substrate, At least 1 piece of the said board | substrate consists of the board | substrate which consists of a material containing silicon, or silicon. It is one of a substrate in which a layer made of another material is provided on the surface of the substrate, or a glass substrate.
The manufacturing method of the 4th bonding board | substrate of this invention is a manufacturing method of the bonding board | substrate in any one of said 1st thru | or 3, and at least 1 piece of the said board | substrate is aluminum, gold | metal | money, silver, platinum, It is characterized by being made of a metal or alloy containing at least one element of titanium, molybdenum, and tungsten.
The manufacturing method of the 5th bonding board | substrate of this invention WHEREIN: At least 1 sheet of the said board | substrate consists of ceramics in the manufacturing method of the bonding board | substrate in any one of said 1st thru | or 4. It is a feature.
The manufacturing method of the 6th bonding board | substrate of this invention consists of a material different from the said board | substrate between the said board | substrates bonded together in the manufacturing method of the bonding board | substrate in any one of said 1st thru | or 5. The substrate is bonded to each other with a metal layer or an alloy layer interposed.

The method of manufacturing a semiconductor device of the invention features the use of method of any lamination substrate among the first to sixth.

  According to the present invention, it is possible to remove the voids and bubbles between the substrates that are hermetically sealed by reducing the pressure in the sealing container, and then the pressure exceeding the atmospheric pressure using the pressurizing fluid in the pressurized container. By applying pressure, the distribution of the pressurizing pressure can be made uniform, and uniform bonding without voids or distortion can be achieved. As a result, a highly reliable bonded substrate can be manufactured with high yield, and a highly reliable semiconductor device can be manufactured using the bonded substrate.

Hereinafter, the manufacturing method of the bonding substrate which concerns on one embodiment of this invention, the bonding substrate manufactured by it, and its bonding substrate are demonstrated with reference to drawings.
FIG. 1 is a diagram showing a first silicon substrate and a second silicon substrate to be bonded, and FIG. 2 is a diagram showing a state in which the silicon substrate is accommodated in a sealing container before decompression. 3 is a view showing a state in which the inside of the sealing container is decompressed following the state of FIG. 2, and FIG. 4 is a view showing a process of accommodating and pressurizing the sealing container in the pressurizing container, and FIG. These are figures which show an example of the time transition of the pressure and temperature in the pressurization process in the pressurization container shown in FIG.

In the method for manufacturing a bonded substrate, the substrate to be bonded is as shown in FIG. First, a first silicon substrate 1, SiO 2 _(silicon dioxide) layer 1a is formed on one surface thereof, and a second silicon substrate 2. Then, the first silicon substrate 1 and the second silicon substrate 2 face each other through the SiO ₂ layer 1a so that they are accurately aligned and overlapped.

Subsequently, as shown in FIG. 2, the stacked substrates 1 and 2 are accommodated in a bag-like sealing container 3. At this stage, the pressure in the sealing container 3 remains at atmospheric pressure. As the container 3 for sealing, for example, a bag-like container made of a material having high tear strength and no possibility of causing pinholes and having appropriate flexibility and flexibility is suitable.
After accommodating both the substrates 1 and 2 superimposed on the sealing container 3, the inside of the sealing container 3 is decompressed as shown in FIG. By this decompression, bubbles and voids between the substrates 1 and 2 accommodated in the sealing container 3 are removed. Then, the entrance / exit 4 of the container 3 for sealing is sealed in the state hold | maintained at the pressure-reduced state.

  Then, as shown in FIG. 4, the sealing container 3 that hermetically accommodates both the substrates 1 and 2 stacked under reduced pressure is accommodated in the pressurized container 5, and refueled from the oil filler port 7 into the pressurized container 5. A pressurizing fluid 6 such as pressurizing oil is filled by a pump (not shown). At this time, as schematically shown in FIG. 4, a plurality of sealing containers 3 can be accommodated in the pressurized container 5 and bonded together.

After the pressurizing container 5 is filled with the pressurizing fluid 6, the pressure of the pressurizing fluid 6 is increased by, for example, the pressurizing cylinder 8, and the atmospheric pressure such as 1.1 atm. Pressurize to a pressure exceeding. In parallel with this, the heater 9 heats the temperature in the pressurized container 5 to a temperature of 50 ° C. or higher, for example, 300 ° C. By this heating, it is possible to realize stronger bonding between the substrates 1 and 2.
By such pressurization and heating, the first silicon substrate 1 and the second silicon substrate 2 are bonded evenly and uniformly over substantially the entire surface thereof without generating bubbles or voids.

  Thus, according to the manufacturing method of the bonding substrate which concerns on this Embodiment, the 1st silicon substrate 1 sealed and accommodated in the sealing container 3 by decompressing the inside of the sealing container 3 and Gaps and bubbles between the second silicon substrate 2 can be removed. Then, in the pressurization vessel 5, by using the pressurization fluid 6, the pressure in the pressurization vessel 5 is pressurized to a pressure exceeding the atmospheric pressure, so that the distribution of the pressurization pressure is made uniform by the static fluid pressure. It is possible to achieve a uniform distribution without gaps or distortion between the substrates 1 and 2. As a result, a highly reliable bonded substrate can be manufactured with high throughput and high yield, and a semiconductor device such as a light-emitting diode element with high reliability (or long life) can be manufactured using the substrate. It becomes possible to do.

In addition, since a large number of sealing containers 3 can be accommodated in the pressurized container 5 and bonded together at a time, the bonding can be performed at a very high throughput using a small manufacturing (pressure processing) apparatus. A composite substrate can be manufactured.
That is, in the pressurizing process using the pressurizing fluid 6, if the entire pressurization target is immersed in the pressurizing fluid 6 (if surrounded), the static fluid pressure can be uniformly sealed by itself. Since it will be applied to the board | substrates 1 and 2 in the container 3, the volume which only added the volume of the minimum quantity of the fluid 6 for pressurization which surrounds it to the volume of the container 3 for sealing which is the pressurization object If there exists, it will become possible to perform the above pressurization processes. Therefore, the volume in the pressurized container 5 can be as small as that.
For example, using an extremely small pressurized container 5 having an internal volume of about 30 cm in length x width x height, about 50 pairs of wafers having a diameter of 6 inches can be bonded together in one press treatment. It becomes possible.

  In this way, in all respects, the occupied floor area per unit of the production apparatus (pressurized container 5), the number of wafers that can be bonded at one time (in other words, throughput), and the production yield, The manufacturing method which concerns on embodiment is far superior to the manufacturing method by the pasting process using the conventional mechanical pressing force.

Here, for comparison with the manufacturing method according to the present embodiment, a case where the superimposed substrates are simply immersed in the pressurizing fluid 6 and pressurized is considered. Such inconvenience occurs.
For example, when a first silicon substrate having a SiO ₂ thin film formed on the surface and another second silicon substrate are bonded together, the difference in lattice constant between Si of the first silicon substrate and the SiO ₂ thin film As a result, the first silicon substrate is likely to be distorted. When the distorted first silicon substrate and the second silicon substrate are overlapped, a gap is generated between the two substrates. If both substrates in which such voids are generated are immersed in the pressurizing fluid 6 such as pressurizing oil in the bare state as they are, the pressurizing fluid 6 enters the voids. Even if the pressure is applied to 6 to pressurize both substrates, the gap cannot be eliminated. This is because the pressurizing fluid 6 that has entered the gap is also subjected to the same pressure as the pressure for adhering the two substrates from the outside.

  Therefore, according to the manufacturing method according to the present embodiment, before the pressurizing process using the pressurizing fluid 6 is performed, the inside of the sealing container 3 is depressurized to be accommodated in the sealing container 3. Air bubbles and voids between the substrates 1 and 2 are removed. In addition, following the decompression process, the substrates 1 and 2 together with the sealing container 3 are placed in the pressurizing fluid 6 while the substrates 1 and 2 are hermetically accommodated in the sealing container 3. Since it is installed, it is possible to omit a complicated operation of taking out both the substrates 1 and 2 from the sealing container 3 one by one when shifting from the decompression process to the pressurization process. In addition, since both substrates 1 and 2 are sealed and accommodated in the sealing container 3 in the pressurizing fluid 6, even if a minute gap remains after the decompression process, The pressurizing fluid 6 can be prevented from entering the gap, and the remaining minute gap can be more reliably removed by the pressurizing process.

  The pressurized fluid 6 is preferably a liquid such as pressurizing oil. Alternatively, a gas such as an inert gas can be used. However, the gas generally has a high compressibility, a large volume change with respect to a temperature change, and a low thermal conductivity. It is more preferable to use a liquid that has the opposite tendency. In general, a liquid has almost no compressibility, hardly changes in volume with respect to a temperature change, and has a good thermal conductivity. Therefore, the liquid is extremely suitable for the pressure treatment and heat treatment in the manufacturing method according to the present embodiment. It has characteristics. However, it is needless to say that the pressurizing fluid 6 is not limited to a liquid. For example, if high-temperature or high-speed heat treatment is not performed, or if heat conductivity and pressure uniformity during heat treatment can be sufficiently ensured, it is harmless to humans such as air and nitrogen and is available. A gas that is easy to handle may also be used.

  Further, as the material of the substrate, a wafer made of a silicon single crystal as described above (second silicon substrate 2) or a wafer formed by providing a silicon oxide layer on the surface of a silicon single crystal substrate (first silicon substrate 1). Of course, it is not limited to only). In addition, for example, a glass substrate, a quartz substrate, a sapphire substrate, and the like are possible. Or for the purpose of improving heat dissipation, for example, a metal made of ceramics such as silicon carbide, or a metal containing at least one element of aluminum, gold, silver, platinum, titanium, molybdenum, and tungsten Or what consists of alloys is also possible. Alternatively, a replacement substrate or the like in which a metal layer or an alloy layer made of a material different from the substrate is interposed between the substrates to be bonded and the both substrates are bonded can also be applied. Alternatively, it is needless to say that wafers having surfaces made of silicon single crystals can be bonded together.

The bonded substrate manufactured by the manufacturing method according to the present embodiment is used as a bonded substrate for a so-called semiconductor device such as a semiconductor integrated circuit such as an IC or LSI, or a light emitting diode element. Is possible.
Alternatively, the present invention can be applied to the manufacture of a complicated lens system in which lenses having different refractive indexes and chromatic dispersions are combined and joined, such as an achromatic lens.
Also proposed in FAKish, et al., “Very high efficiency semiconductor wafer-bonded transparent substrate lightemitting diodes”, Appl. Phys. Lett., Vol. 64, no21, pp. 2839-2841, May1994. A light-emitting element that improves the efficiency by replacing the substrate supporting the light-emitting layer with a material that is transparent to the light emission wavelength, and a high-efficiency light-emitting device that has a reflective submount proposed in Japanese Patent Publication No. 2005-51378 It is also possible to apply to the manufacturing method of an element. Alternatively, for example, it can be applied to the manufacture of a photonic crystal device proposed in Japanese Patent Application Laid-Open No. 2000-332351.

The bonding substrate was manufactured by the manufacturing method including the bonding process as described in the above embodiment.
A SiO ₂ layer 1a having a thickness of 10 nm was formed on a silicon wafer having a diameter of 152.4 mm and a thickness of 600 μm by a CVD method, whereby a first silicon substrate 1 was manufactured. Apart from that,
A wafer made of single crystal silicon having a diameter of 152.4 mm and a thickness of 600 μm was prepared as the second silicon substrate 2. Then, the first silicon substrate 1 and the second silicon substrate 2 are overlapped with each other through the SiO ₂ layer 1a, and both of them are placed in a bag-like sealing container 3 made of aluminum foil having a predetermined strength. The substrates 1 and 2 were accommodated, and the inside of the sealing container 3 was depressurized using a vacuum sealing device (not shown) and sealed in that state. In such a procedure, three sealing containers 3 in which the stacked substrates 1 and 2 were sealed in a reduced pressure state were accommodated in the pressurized container 5. Since each sealing container 3 is provided with a locking hole 10 at a position that does not impair the sealed state, the locking hole 10 is suspended from a bar-shaped locking arm 11 provided in the pressurized container 5. In this way, three sealing containers 3 were arranged.

Subsequently, the pressurizing cylinder 8 was attached, and the pressurizing oil as the pressurizing fluid 6 was filled into the pressurizing container 5 in which the three sealing containers 3 were housed. And the fluid 6 for pressurization was heated to 300 degreeC using the heater 9 at the timing as shown in FIG. Five minutes after reaching 300 ° C., the pressure of the pressurizing fluid 6 was increased to 245 N / cm ² (about 25 kgf / cm ² ) using the cylinder 8, and the pressure was continued for 30 minutes.
After 30 minutes have passed, the pressurizing fluid 6 is discharged from the pressurization vessel 5 through the discharge port 12, and the pressurization cylinder 8 which is also used as a lid of the pressurization vessel 5 is removed, and three sealings are used. The container 3 was taken out. And the container 3 for sealing was opened, and both the board | substrates 1 and 2 (namely, bonding board | substrate) of the bonded state were collect | recovered from each.

  Thus, about the 3 bonding board | substrates with which both board | substrates 1 and 2 were bonded together, the bonding interface of bonding was observed with the ultrasonic microscope. As a result, it was confirmed that no interfacial peeling or void occurred at all for all three bonded substrates. Of course, no damage or the like occurred. Thus, according to the manufacturing method which concerns on the Example of this invention, it was confirmed that equal bonding without a space | gap, a distortion | strain, etc. is realizable.

Here, the pressure in the pressurized container 5 is a pressure exceeding the atmospheric pressure, for example, 1.1 atmospheres or more, for example. It is preferable to set the pressure so that it can be combined (surface bonding).
In general, a substrate typified by a silicon wafer tends to be difficult to bond at room temperature such as 25 ° C. except in the case of high vacuum adsorption, but it is heated by heating the vicinity of the bonding interface of the substrate. In the vicinity of the bonding interface, melting, chemical change, or mutual diffusion at the atomic level occurs to facilitate bonding. It is desirable to set the temperature at which bonding is facilitated to 50 ° C. or higher.
Further, the larger the pressure difference between the pressure in the sealing container 3 and the pressure of the pressurizing fluid 6 in the pressurizing container 5, the greater pressure can be applied to both the substrates 1 and 2. Both substrates 1 and 2 can be bonded together. Further, the pressure in the sealing container 3 is equal to or lower than the atmospheric pressure because the decompression process is performed before the pressurization process. In general, the atmospheric pressure rises and falls within a predetermined range depending on the weather specific to each region, and it is preferable to set the atmospheric pressure to 1.1 atm or less in consideration of them. Alternatively, when it is desired to more reliably remove voids and bubbles in the decompression process, the pressure at the time of depressurization is less than 1 atm so that the voids and bubbles can be removed with sufficient certainty. desirable.
In addition, the duration of the heating state and the duration of pressurization are not limited to the above-described examples and embodiments, and are appropriately set so as to realize bonding without voids more reliably. It is possible to change to

It is a figure which shows the 1st silicon substrate and 2nd silicon substrate which are the object of bonding. It is a figure which shows the state which accommodated the silicon substrate in the container for sealing before decompressing. FIG. 3 is a view showing a state where the inside of the sealing container is sealed by reducing the pressure following the state of FIG. 2. It is a figure which shows the process of accommodating the container for sealing in a pressurization container, and pressurizing. It is a figure which shows an example of the time transition of the pressure and temperature in the pressurization process in the pressurization container shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st silicon substrate 2 2nd silicon substrate 1a SiO ₂ layer 3 Sealing container 4 Entrance / exit 5 Pressurization container 6 Pressurization fluid 7 Oil supply port 8 Pressurization cylinder 9 Heater 10 Locking hole 11 Locking arm 12 Outlet

Claims (7)

Stacking two or more substrates, storing them in a flexible sealing container, and depressurizing and sealing the inside of the sealing container;
Storing the sealing container in which the superposed substrate is sealed in a pressurized container, and pressurizing the pressurizing fluid in the pressurized container to a pressure exceeding atmospheric pressure;
And a step of heating the inside of the pressurized container to 50 ° C. or higher. In the manufacturing method of the bonding board | substrate of Claim 1,
A method for producing a bonded substrate, comprising: reducing the pressure in the sealing container to 1.1 atm or less in the step of sealing the inside of the sealing container by reducing the pressure. In the manufacturing method of the bonding board | substrate of Claim 1 or 2,
At least one of the substrates is a substrate made of a material containing silicon, a substrate formed by providing a layer made of another material on the surface of the substrate containing silicon, or one of a glass substrate. The manufacturing method of the bonding board | substrate characterized. In the manufacturing method of the bonding board | substrate of any one of Claims 1 thru | or 3,
At least one of the substrates is made of a metal or alloy containing at least one element selected from aluminum, gold, silver, platinum, titanium, molybdenum, and tungsten. Production method. In the manufacturing method of the bonding board | substrate of any one of Claims 1 thru | or 4,
At least 1 sheet of the said board | substrate consists of ceramics, The manufacturing method of the bonding board | substrate characterized by the above-mentioned. In the manufacturing method of the bonding board | substrate of any one of Claims 1 thru | or 5,
A method for producing a bonded substrate, characterized in that a metal layer or an alloy layer made of a material different from that of the substrate is interposed between the substrates to be bonded together to bond the substrates together. A method for manufacturing a semiconductor device, wherein the method for manufacturing a bonded substrate according to any one of claims 1 to 6 is used .

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