JP2010191310A - Method for manufacturing multilevel grayscale photomask and method for manufacturing semiconductor transistor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress a resist pattern from peeling and to suppress generation of black defects. <P>SOLUTION: A method for manufacturing a multilevel grayscale photomask is provided, including steps of: preparing a mask blank having a semitransparent film and a light-shielding film formed in this order on a light-transmitting substrate and having a first resist film formed on the outermost layer; forming a light-shielding film pattern by etching the light-shielding film using the first resist pattern as a mask and forming a light-transmitting portion by etching the semitransparent film using the first resist pattern or the light-shielding film pattern as a mask; forming a second resist film covering the whole surface of the substrate which is obtained by removing the first resist pattern; and forming a semitransparent portion and a light-shielding portion by etching the light-shielding film pattern using the second resist pattern as a mask. In the step of forming the second resist film, prior to forming the second resist film, an exposed surface of the light-transmitting substrate appearing by the formation of the light-transmitting portion is subjected to a surface treatment with a Si-containing organic compound. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a multi-tone photomask used for manufacturing a flat panel display (hereinafter referred to as FPD) such as a liquid crystal display device, and a method for manufacturing a semiconductor transistor.

  In recent years, in order to reduce the number of photomasks necessary for manufacturing an FPD, a multi-tone photomask having a pattern including a light transmitting portion, a light shielding portion, and a semi-light transmitting portion has been used. As such a photomask, one in which a semi-translucent portion is constituted by a fine light-shielding pattern is known. Also, for the reason that the design and manufacture are easier than a gray-tone mask, a half-tone type in which a semi-translucent portion is composed of a semi-transparent film has been put into practical use.

JP 2007-256922 A

  The above-described halftone type multi-tone photomask is manufactured as follows, for example. First, a mask blank is prepared in which a semi-transparent film and a light-shielding film are sequentially formed on a translucent substrate, and a first resist film is formed as the uppermost layer. Then, a pattern is drawn on the first resist film and developed to form a first resist pattern that covers the formation planned region of the light shielding part and the formation planned region of the semi-translucent part. Then, the light-shielding film and the semi-transparent film are etched using the first resist pattern as a mask to form a translucent part. Alternatively, the light-shielding film may be etched using the first resist pattern as a mask, and the translucent film may be etched using the light-shielding film pattern as a mask. Then, a second resist film that covers the entire surface of the substrate obtained by removing the first resist pattern is formed. Then, a pattern is drawn on the second resist film and developed to form a second resist pattern that covers the region where the light shielding portion is to be formed. Then, the light-shielding film is etched using the second resist pattern as a mask to form a semi-translucent portion and a light-shielding portion.

  However, in the above-described method, it has been difficult to completely prevent the positional deviation between the drawing position of the first resist pattern and the drawing position of the second resist pattern. This is because the accuracy of the drawing machine and alignment is limited. For example, if the outer edge of the second resist pattern is shifted and aligned to the inside of the region where the light shielding part is to be formed at the boundary between the region where the light shielding part is to be formed and the light transmitting part, the light shielding at the boundary is performed in the subsequent etching process. The film will be etched unintentionally. And the dimension and shape of a light-shielding part may differ from a design value, or the base semi-transparent film may be exposed and an unnecessary semi-translucent part may be formed. In addition, for example, in a TFT pattern, a transfer pattern in which two light-shielding portions are opposed to each other with a semi-transparent portion may be used. Here, the semi-translucent portion corresponds to the channel portion, and the two light shielding portions correspond to the source and the drain, respectively. At this time, if the above-described misalignment occurs, the area of the source or drain becomes different from the design value, and the length of the facing portion becomes smaller than the design value, which affects the TFT performance. .

Therefore, a method of providing a predetermined margin area in advance in a resist pattern to be drawn is considered in order to prevent a serious influence on a device to be obtained even if the above-described positional deviation occurs in the drawing position. It is done. For example, if drawing is performed with a margin region provided so that the dimension of the second resist pattern is enlarged by a predetermined amount on the light-transmitting portion side at the boundary between the region where the light-shielding portion is to be formed and the light-transmitting portion, light shielding at the boundary is performed. It can be avoided that the film is etched unintentionally.

  By the way, when the second resist pattern is drawn by providing a margin region so as to be enlarged by a predetermined amount on the light transmitting portion side at the boundary between the light shielding portion formation region and the light transmitting portion, the resist film constituting the margin region is drawn. Will have a contact surface with the translucent substrate. Then, development is performed in this state, and the process proceeds to the next etching step. Note that a photomask for manufacturing an FPD is large in size and has a rectangular shape with a side of 300 mm or more, and a large photomask has a rectangular shape with a side exceeding 1000 mm. For this reason, it is advantageous to use wet etching in the etching process due to restrictions on the apparatus. However, the inventors have found that the adhesion between the resist film constituting the margin region and the translucent substrate is not so high, and even when they are in close contact, they may be peeled off when exposed to the etching solution. It was done.

  When the resist film constituting the margin region is partially peeled off from the surface of the translucent substrate, it adheres to the light-shielding film that has not yet been etched, and the etching of that portion is hindered, thereby causing pattern defects. The inventors have found that this may occur. For example, when the resist film is partially peeled, a part of the peeled resist film is reattached to the surface of the light shielding film, and the light shielding film to be etched remains in the subsequent etching process (unintentional) This is a defect in which a light-shielding portion is generated, and is sometimes referred to as a black defect).

  Further, according to the inventors, when a gap is formed between the resist film constituting the margin region and the light-transmitting substrate after the second resist pattern is formed, the etching behavior is caused by the etching solution that has entered the portion. It has been found that changes occur in the etching rate and affect the etching rate.

  An object of this invention is to provide the manufacturing method of the photomask which can suppress peeling of a resist pattern and can suppress generation | occurrence | production of a black defect. It is another object of the present invention to achieve precise patterning with high reproducibility by stabilizing the etching behavior.

  A first aspect of the present invention is a method for manufacturing a multi-tone photomask having a transfer pattern including a light-transmitting portion, a light-shielding portion, and a semi-light-transmitting portion, and a semi-transparent film on a light-transmitting substrate. A step of preparing a mask blank in which a light shielding film is formed in this order and a first resist film is formed on the uppermost layer; and a pattern is drawn on the first resist film and developed to form the light shielding portion Forming a first resist pattern covering each of the region and the region where the semi-translucent portion is to be formed, etching the light shielding film using the first resist pattern as a mask to form a light shielding film pattern; A first patterning step of forming the light-transmitting portion by etching the semi-transparent film using the resist pattern or the light-shielding film pattern as a mask, and the entire surface of the substrate obtained by removing the first resist pattern Forming a second resist film, drawing a pattern on the second resist film and developing the second resist film to form a second resist pattern that covers a region where the light shielding portion is to be formed; A second patterning step of forming the semi-translucent portion and the light-shielding portion by etching the light-shielding film pattern using a pattern as a mask. In the step of forming the second resist film, Prior to the formation of a resist film, a multi-tone photomask manufacturing method is provided in which a surface treatment with a Si-containing organic compound is performed on the surface of the translucent substrate exposed by forming the translucent portion.

According to a second aspect of the present invention, the second resist pattern has a margin region that is enlarged toward the light-transmitting portion at a boundary between the region where the light-shielding portion is to be formed and the light-transmitting portion. The method for producing a multi-tone photomask described in 1).

  According to a third aspect of the present invention, in the second aspect, the margin region covers a side surface of the translucent film and a side surface of the light shielding film at the boundary, and covers a partial surface of the light transmitting part. It is a manufacturing method of the described multi-tone photomask.

  A fourth aspect of the present invention is the method for producing a multi-tone photomask according to any one of the first to third aspects, wherein the etching performed in the first patterning step and the second patterning step is wet etching. is there.

  A fifth aspect of the present invention is the multi-tone photo according to any one of the first to fourth aspects, wherein the light shielding film is made of chromium or a compound thereof, and the semi-transparent film is made of molybdenum silicide or a compound thereof. It is a manufacturing method of a mask.

  A sixth aspect of the present invention is a method for producing a multi-tone photomask, wherein the Si-containing organic compound is hexamethyldisilane.

  A seventh aspect of the present invention is a method for manufacturing a semiconductor transistor, wherein the multi-tone photomask according to any one of the first to sixth aspects is irradiated with exposure light, and the transfer pattern is transferred to a transfer target.

  According to the photomask manufacturing method of the present invention, it is possible to suppress the peeling of the resist pattern and suppress the occurrence of black defects. Furthermore, the etching behavior can be stabilized and precise patterning with high reproducibility can be realized.

(A) is a fragmentary sectional view of the photomask which concerns on one Embodiment of this invention, (b) is a fragmentary top view of this photomask. It is the schematic which shows the flow of the manufacturing method of the photomask which concerns on one Embodiment of this invention. It is the schematic which shows the flow of the manufacturing method of the conventional photomask. It is the schematic which shows the flow of the manufacturing method of the conventional photomask. (A) is a schematic block diagram of the surface treatment apparatus used with the manufacturing method of the photomask which concerns on one Embodiment of this invention, (b) is XX sectional drawing of Fig.4 (a).

<One Embodiment of the Present Invention>
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1A is a partial cross-sectional view of a photomask according to an embodiment of the present invention, and FIG. 1B is a partial plan view of the photomask. FIG. 2 is a schematic view showing a flow of a photomask manufacturing method according to an embodiment of the present invention. FIG. 5A is a schematic configuration diagram of a surface treatment apparatus used in a photomask manufacturing method according to an embodiment of the present invention, and FIG. 5B is a cross-sectional view taken along line XX in FIG. It is.

(1) Configuration of Photomask The configuration of the photomask 100 according to the present embodiment will be described below with reference to FIGS. 1 (a) and 1 (b).

  The photomask 100 according to the present embodiment is configured as an exposure mask used in, for example, a manufacturing process of a display device (FPD) such as a liquid crystal display. As shown in the enlarged cross-sectional view of FIG. 1, the photomask 100 includes a light-transmitting substrate 101, a semi-transparent film 102 formed on a part of the surface of the light-transmitting substrate 101, and one of the semi-transparent films 102. A light shielding film 103 formed on the surface of the part.

  On the surface of the translucent substrate 101, a transfer pattern including a translucent part 111, a semi-translucent part 112 and a light shielding part 113 is provided. The translucent part 111 is formed by exposing the surface of the translucent substrate 101. The semi-translucent portion 112 is formed by forming only the semi-transparent film 102 on the surface of the translucent substrate 101. The light shielding portion 113 is formed by laminating the semi-transparent film 102 and the light shielding film 103 on the surface of the translucent substrate 101 in this order (so that the semi-transparent film 102 is a lower layer and the light shielding film 103 is an upper layer). . The planar shapes of the light transmitting portion 111, the light shielding portion 113, and the semi-light transmitting portion 112 are configured in various shapes according to a circuit pattern (device pattern) formed on the display device substrate. For example, when a TFT or the like is manufactured, it is configured in a planar shape as shown in FIG.

The translucent substrate 101 is configured as a flat plate made of, for example, quartz (SiO ₂ ) glass, low expansion glass containing SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , RO, R ₂ O, or the like. The main surface (front surface and back surface) of the translucent substrate 101 is configured to be flat and smooth by polishing or the like. The translucent substrate 101 can be, for example, a rectangle having a side of 300 mm or more, or a rectangle having a side of, for example, 2000 to 2400 mm, and the thickness of the translucent substrate 101 can be, for example, 3 mm to 20 mm.

  The semi-transparent film 102 transmits light of, for example, 20 to 60% with respect to the amount of light (exposure light) transmitted through the light transmitting portion 111 (translucent substrate 101) when the photomask 100 is used. It is configured as a semipermeable membrane. The translucent film 102 is made of molybdenum silicide (MoSi) containing, for example, molybdenum (Mo) and silicon (Si). The translucent film 102 is not limited to being composed of only MoSi, but may be composed of nitride, oxide, oxynitride, or the like containing MoSi as a main component. The semi-translucent film 102 has etching resistance to the chromium etching solution, and functions as an etching stopper layer when the light shielding film 103 is etched using the chromium etching solution as will be described later. The thickness of the semi-transparent film 102 can be determined by the transmittance to be obtained, and can be, for example, 2 to 50 nm.

  The light shielding film 103 is configured as a film having a light shielding property against exposure light when the photomask 100 is used. Only the light shielding film 103 may have a light shielding property of, for example, an optical density of about 3.0, or the light shielding property may be realized by a combination with the semi-transparent film 102. For example, the light shielding film 103 can be mainly composed of Cr (chromium). For example, if the light shielding film 103 is formed by laminating a Cr compound (CrO, CrC, CrN, etc.) on the surface of a layer made of substantially Cr, reflection suppression for exposure light (drawing light) on the surface of the light shielding film 103 is suppressed. Can have a function. In addition, the light shielding film 103 according to the present invention may have one reflection suppressing layer as in the present embodiment, or may be configured by more layers. In such a case, it is preferable that at least the uppermost layer of the stacked films is configured as the above-described antireflection film. The thickness of the light shielding film 103 can be set to, for example, 50 nm to 300 nm.

(2) Photomask Manufacturing Method Next, a photomask manufacturing method according to the present embodiment will be described with reference to FIGS.

(Mask blank preparation process)
First, as shown in FIG. 2A, a mask blank in which a semi-transparent film 102 and a light-shielding film 103 are formed in this order on a translucent substrate 101, and a first resist film 104 is formed as the uppermost layer. 100b is prepared. Note that the first resist film 104 can be formed of a positive photoresist material or a negative photoresist material. In the following description, it is assumed that the first resist film 104 is formed from a positive photoresist material. The first resist film 104 can be formed using a technique such as spin coating or slit coater.

(First patterning step)
Next, as shown in FIG. 2B, the first resist film 104 is subjected to drawing exposure by a laser drawing machine or the like, so that the first resist film 104 is exposed. Thereafter, the developing solution is supplied to the first resist film 104 by a technique such as a spray method and developed, and the first resist pattern 104p covering the formation planned area of the light shielding portion 113 and the formation planned area of the semi-translucent portion 112, respectively. Form.

Next, as shown in FIG. 2C, the light shielding film 103 is etched using the formed first resist pattern 104p as a mask to form the light shielding film pattern 103p, and the first resist pattern 104p or the light shielding film is formed. The translucent film 102 is etched using the pattern 103p as a mask to expose the surface of the translucent substrate 101, thereby forming a translucent portion 111. Note that when the semi-transparent film 102 is etched using the light-shielding film pattern 103p as a mask, the first resist pattern 104p may be peeled off. For the etching of the light shielding film 103, for example, a chromium etching solution made of pure water containing ceric ammonium nitrate ((NH ₄ ) ₂ Ce (NO ₃ ) ₆ ) and perchloric acid (HClO ₄ ) is used. This can be done by supplying the light shielding film 103 by a technique. The semi-transparent film 102 can be etched by supplying a fluorine (F) -based etching solution (or etching gas) to the semi-transparent film 102.

(Second resist film forming step)
When the formation of the light transmitting portion 111 is completed, the first resist pattern 104p is peeled off. The resist pattern 252p can be peeled by bringing the resist pattern 252p into contact with a stripping solution and stripping. Thereafter, the substrate obtained by removing the first resist pattern 104p (the surface of the light-transmitting substrate 101 is exposed in the light-transmitting portion 111, and the semi-light-transmitting film 102 and the light-shielding film 103 in other regions). A substrate in which these are stacked in this order) is called an intermediate substrate 100c.

Next, as shown in FIG. 2D, a surface treatment is performed in which a Si-containing organic substance is brought into contact with the surface of the light-transmitting substrate 101 exposed at least with the light-transmitting portion 111 formed. The organic substance enhances the adhesion between the translucent substrate and the resist, and a known silane coupling agent can be used. Examples of the Si-containing organic substance include hexamethyldisilazane, 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, octadecyltri Any of chlorosilane, octadecyltrimethoxysilane, vinyltrimethoxysilane, and allyltrimethoxysilane can be used. In the following embodiment, a surface treatment for supplying hexamethyldisilazane ((CH ₃ ) ₃ SiNHSi (CH ₃ ) ₃ ) (commonly called HMDS) is performed.

The surface treatment can be performed using, for example, a surface treatment apparatus 500 shown in FIG. A surface treatment apparatus 500 shown in FIG. 5 includes a treatment container 510 configured as a sealed container. The above-described intermediate substrate 100c is loaded into the processing container 510. In the processing container 510, a holder 550 that holds the loaded intermediate substrate 100c in a vertical posture, for example, and a heater 560 that heats the intermediate substrate 100c held by the holder 550 are provided. A nozzle 520 for supplying the above-described Si-containing organic compound (here, hexamethyldisilazane is used) is provided above the processing container 510. The nozzle 520 is provided with a plurality of openings for ejecting hexamethyldisilazane. The upstream side of the nozzle 520 is connected to a vaporizer 530 provided outside the processing container 510. Liquid hexamethyldisilazane is stored in the vaporizer 530. The upstream end of the nozzle 520 opens to a space above the liquid hexamethyldisilazane stored in the vaporizer 530. A carrier gas supply pipe 540 that supplies N ₂ gas as a carrier gas is connected to the vaporizer 530. The downstream end of the carrier gas supply pipe 540 is immersed in liquid hexamethyldisilazane stored in the vaporizer 530.

The surface treatment is performed as follows, for example. First, the surface of the intermediate substrate 100c obtained by peeling off the first resist pattern 104p is cleaned using, for example, pure water, acid, alkali, or the like, and foreign matter (first surface) attached to the surface of the intermediate substrate 100c. The debris and the like of the resist pattern 104p are removed. Then, the cleaned intermediate substrate 100 c is carried into the processing container 510, and the surface of the intermediate substrate 100 c is heated to 100 to 150 ° C. by the heater 560. Then, N ₂ gas is supplied into the vaporizer 530 from the carrier gas supply pipe 540. As a result, liquid hexamethyldisilazane stored in the vaporizer 530 is bubbled and vaporized, and a mixed gas of the vaporized hexamethyldisilazane and N ₂ gas passes through the nozzle 520 into the processing vessel 510. To be introduced. The mixed gas supplied into the processing container 510 is supplied to at least the surface of the light-transmitting substrate 101 that is exposed by forming the light-transmitting portion 111 and modifies the surface (for example, the surface and a process described later). To improve the adhesion with the second resist film 105 formed in step 1). Then, after about one hour has passed, the introduction of the mixed gas into the processing container 510 is stopped, the intermediate substrate 100c is carried out of the processing container 510, and the surface treatment is finished. The above treatment can be carried out at normal pressure. It is desirable to make contact with hexamethyldisilane within 1 hour, more preferably within 30 minutes from the above heating, and within 1 hour, more preferably within 30 minutes after the surface treatment is completed. It is desirable to apply.

  Next, as shown in FIG. 2E, a second resist film 105 covering the entire surface of the intermediate substrate 100c after the surface treatment is formed. The second resist film 105 can be composed of a positive photoresist material or a negative photoresist material. In the following description, it is assumed that the second resist film 105 is formed from a positive photoresist material. The second resist film 105 can be formed using a technique such as spin coating or slit coater.

(Second patterning step)
Next, as shown in FIG. 2F, the second resist film 105 is subjected to drawing exposure by a laser drawing machine or the like, so that the second resist film 105 is exposed. Thereafter, the developer is supplied to the second resist film 105 by a technique such as a spray method and developed, and as shown in FIG. 2G, the formation region of the light shielding part 113 and the formation of the semi-translucent part 112 are planned. A second resist pattern 105p that covers each region is formed.

When performing drawing exposure on the second resist film 105, as shown in FIG. 2F, the second resist pattern 105p is formed at the boundary between the region where the light shielding portion 113 is to be formed and the light transmitting portion 111. Is drawn using drawing data processed so as to be enlarged by a predetermined amount toward the translucent portion 111 side. For example, at the boundary, the light shielding portion is drawn so as to be enlarged toward the light transmitting portion within a range of about 0.5 to 2.0 μm, more preferably 0.5 to 1.0 μm from the design value. As a result, as shown in FIG. 2G, the second resist pattern 105p has a margin that is enlarged by a predetermined amount toward the light transmitting portion 111 at the boundary between the region where the light shielding portion 113 is to be formed and the light transmitting portion 111. It will have the area | region 105m. The margin region 105m covers the side surface of the semi-transparent film 102 and the side surface of the light shielding film 103 at the boundary, and the translucent substrate 10 in the translucent part 111.
A part of the surface of 1 is covered. The width of the margin area 105m is appropriately set based on the amount of positional deviation assumed when the second resist pattern 105p is drawn.

  Then, the light shielding film 103 is etched using the formed second resist pattern 105p as a mask. The light shielding film 103 can be etched by supplying the above-described chromium etching solution onto the light shielding film 103 by a spray method or the like. As described above, the semi-transparent film 102 has etching resistance to the chromium etching solution, and thus remains without being etched. As a result, the semi-translucent portion 112 in which only the semi-transparent film 102 is formed on the surface of the translucent substrate 101, and the semi-transparent film 102 and the light-shielding film 103 are formed on the surface of the translucent substrate 101. A light shielding portion 113 is formed in this order (so that the semi-transparent film 102 is the lower layer and the light shielding film 103 is the upper layer).

As described above, the surface of the light-transmitting substrate 101 exposed by forming the light-transmitting portion 111 is modified by supplying a mixed gas of hexamethyldisilazane and N ₂ gas. Adhesion with the second resist film 105 is improved. Therefore, even if the above-described development process and etching process are performed, the second resist pattern 105p is prevented from being peeled off from the surface of the translucent substrate 101. Further, it is possible to prevent the etching solution from entering due to a gap between the resist pattern 105p and the light-transmitting substrate 101 during the etching.

  Next, the second resist pattern 105p is removed, and the manufacturing method of the photomask 100 according to this embodiment is finished. The second resist pattern 105p can be removed by bringing a peeling solution into contact with the second resist pattern 105p for peeling.

  After that, exposure is performed using the manufactured photomask 100, and a pattern (a light transmitting portion 111, a semi-light transmitting portion 112, and a light shielding portion 113) formed on the photomask 100 is formed on the resist layer formed on the display device substrate. Transfer pattern). Specifically, the light from the exposure light source is irradiated to the resist layer formed on the transfer target (display device substrate) through the photomask 100, and the above-described pattern is transferred to the resist layer. Thereafter, a pixel structure based on the transferred pattern is formed on the surface of the display device substrate to complete the manufacture of the display device substrate.

(3) Effects according to the present embodiment According to the present embodiment, the following one or more effects are achieved.

(A) According to the second resist film forming step according to the present embodiment, the second resist pattern 105p is located on the light transmitting part 111 side at the boundary between the region where the light shielding part 113 is to be formed and the light transmitting part 111. Draw to zoom in quantitatively. As a result, as shown in FIG. 2G, the second resist pattern 105p has a margin that is enlarged by a predetermined amount toward the light transmitting portion 111 at the boundary between the region where the light shielding portion 113 is to be formed and the light transmitting portion 111. It will have the area | region 105m. The margin region 105m covers the side surface of the semi-transparent film 102 and the side surface of the light shielding film 103 at the boundary, and covers the surface of the translucent substrate 101 in the translucent part 111. Thereby, even if a deviation occurs between the drawing position of the first resist pattern 103p and the drawing position of the second resist pattern 105p, the occurrence of pattern defects can be suppressed. In other words, even if the second resist pattern 105p is drawn at the boundary between the region where the light shielding part 113 is to be formed and the light transmitting part 111 and is shifted toward the region where the light shielding part 113 is to be formed, the light shielding film is formed at the boundary. The surface of 103 can be prevented from being exposed, and the light shielding film 103 at the boundary can be prevented from being etched. In addition, it is possible to prevent the size and shape of the light-shielding portion 113 from being different from the design value, or exposing the underlying semi-transmissive film 102 to form an unnecessary semi-transmissive portion. Note that when the above-mentioned positional deviation does not occur, a transfer pattern having a dimension as designed is formed.

  For reference, a conventional method of manufacturing a photomask 300 in which no margin region is provided in the second resist pattern will be described with reference to FIG. FIG. 3 is a schematic diagram showing the flow of the conventional method.

  In the conventional method shown in FIG. 3, first, a mask blank 200b in which a semi-transparent film 202 and a light-shielding film 203 are formed in this order on a translucent substrate 201 and a first resist film 204 is formed as the uppermost layer is formed. prepare. Then, a pattern is drawn on the first resist film 204 and developed to form a first resist pattern 204p that covers the area where the light shielding portion 213 is to be formed and the area where the semi-transparent portion 212 is to be formed. Then, the light-shielding film 203 and the semi-transparent film 202 are etched using the first resist pattern 204p as a mask to form a translucent portion 211. Then, a second resist film 205 is formed to cover the entire surface of the substrate obtained by removing the first resist pattern 204p. Then, a pattern is drawn on the second resist film 205 and developed to form a second resist pattern 205p that covers a region where the light shielding portion 213 is to be formed. At this time, drawing is performed so as to match the size and position of the light-shielding portion 213 where the second resist pattern 205p is to be formed without providing a margin region in the second resist pattern 205p. Then, the light-shielding film 203 is etched using the second resist pattern 205p as a mask to form a semi-translucent portion 212 and a light-shielding portion 223, and the second resist pattern 205p is removed to manufacture the photomask 200.

  However, the conventional method shown in FIG. 3 has a problem in that a deviation easily occurs between the drawing position of the first resist pattern 204p and the drawing position of the second resist pattern 205p, and a defect is likely to occur in the pattern to be formed. It was. For example, if the second resist pattern 205p is drawn at a boundary between the region where the light shielding part 213 is to be formed and the translucent part 211, the second resist pattern 205p is shifted toward the region where the light shielding part 213 is to be formed (see symbol A in FIG. 3). In the subsequent etching process, the light shielding film 203 at the boundary is unintentionally etched. Then, the size and shape of the light-shielding part 213 may differ from the design values, or the underlying semi-transparent film 202 may be exposed and an unnecessary semi-transparent part 212a may be formed (see symbol B in FIG. 3). ).

(B) According to the second resist film formation step according to the present embodiment, prior to the formation of the second resist film 105, at least the surface of the translucent substrate 101 exposed by forming the translucent portion 111 is formed. Surface treatment for supplying hexamethyldisilazane is performed. By performing such a process, the surface of the light-transmitting substrate 101 exposed by forming the light-transmitting portion 111 is modified by supplying a mixed gas of hexamethyldisilazane and N ₂ gas, so that the light-transmitting property is obtained. The adhesion between the surface of the substrate 101 and the second resist film 105 is improved. As a result, it is possible to suppress the margin region 105m of the second resist pattern 105p from being peeled off from the surface of the light-transmitting substrate 101 even when the above-described development process or etching process is performed. And it can suppress that a part of peeled 2nd resist pattern 105p adheres to the light shielding film 103 surface, and generation | occurrence | production of the above-mentioned black defect can be suppressed. Further, since no gap is generated between the translucent substrate 101 and the resist pattern 105p, the etching solution does not enter from such a gap. As a result, the etching process can be rapidly advanced while suppressing variations in the etching rate, and the etching behavior can be stabilized and precise etching with high reproducibility can be performed.

  For reference, a conventional method for manufacturing a photomask 300 without surface treatment will be described with reference to FIG. FIG. 4 is a schematic diagram showing the flow of the conventional method.

In the conventional method shown in FIG. 4, first, a mask blank 300b having a semi-transparent film 302 and a light-shielding film 303 formed in this order on a translucent substrate 301 and a first resist film 304 formed on the uppermost layer is formed. prepare. Then, a pattern is drawn on the first resist film 304 and developed to form a first resist pattern 304p that covers the area where the light shielding portion 313 is to be formed and the area where the semi-transparent portion 312 is to be formed. Then, the light-shielding film 303 and the semi-transparent film 302 are etched using the first resist pattern 304p as a mask to form a light-transmitting portion 311. Then, a second resist film 305 is formed to cover the entire surface of the substrate obtained by removing the first resist pattern 304p. Then, a pattern is drawn on the second resist film 305 and developed to form a second resist pattern 305p that covers a region where the light shielding portion 313 is to be formed. At this time, drawing is performed so that the second resist pattern 305p is enlarged by a predetermined amount toward the light transmitting portion 311 at the boundary between the region where the light shielding portion 313 is to be formed and the light transmitting portion 311. Then, the light-shielding film 303 is etched using the second resist pattern 305p as a mask to form a semi-translucent portion 312 and a light-shielding portion 323, and the second resist pattern 305p is removed to manufacture the photomask 300.

  However, in the conventional method shown in FIG. 4, since the second resist film 305 is formed without subjecting the substrate obtained by removing the first resist pattern 304p to the surface of the light-transmitting substrate 301. In some cases, it is difficult to obtain adhesion between the surface and the second resist film 305. Therefore, when the second resist pattern 305p is drawn by providing a margin region on the boundary between the region where the light shielding portion 313 is to be formed and the light transmitting portion 311 so as to be enlarged by a predetermined amount on the light transmitting portion 311 side, the margin region is drawn. The second resist film 305 to be formed partially peeled from the surface of the light-transmitting substrate 301 (see reference numeral C in FIG. 4), thereby causing a pattern defect. For example, when the second resist film 305 constituting the margin region is partially peeled off, a part of the peeled second resist film 305 is reattached to the surface of the light shielding film 303 (see symbol D in FIG. 4). ), A defect (black defect) in which the light shielding film 303 to be etched remains in the subsequent etching process may occur (see symbol E in FIG. 4).

  Further, since a gap is formed between the translucent substrate 310 and the resist pattern 305p, the etchant enters here, and the etchant contacts the cross section of the light shielding film 303 and the cross section of the semi-transparent film 302. May end up. Here, since the light shielding film 303 is mainly composed of Cr and the semi-transparent film 302 is a film made of MoSi, both have a certain degree of conductivity. For this reason, in the cross section of the light shielding film 303 and the cross section of the semi-transparent film 302, electrodes having different potentials immersed in the etching solution are formed (so-called battery effect occurs), which affects the etching behavior. . For example, inconveniences such as a decrease in the etching rate of the light shielding film 303 containing Cr as a main component may occur.

(C) As a method for producing a multi-tone photomask similar to the present invention, there is the following method. That is, a pattern is drawn on the first resist film on the prepared photomask portion and developed to form a first resist pattern that covers a region where the light shielding portion is to be formed, and the light shielding film is formed using the first resist pattern as a mask. Etch. Then, a second resist film that covers the entire surface of the substrate obtained by removing the first resist pattern is formed. Next, there is also a method in which a pattern is drawn on the second resist pattern and developed to form a second resist pattern that covers at least the region where the semi-translucent portion is to be formed, and the light shielding film is etched using this as a mask. However, according to this method, since the semi-transparent film is exposed to two development and cleaning steps, the semi-transparent film material may be damaged and the transmittance may be changed. On the other hand, according to the present embodiment, since the semi-transparent film is exposed to the wet treatment only once, there is an advantage that the transmittance control as a multi-tone photomask becomes easy. And the effect of the surface treatment by this embodiment is acquired notably.

<Other Embodiments of the Present Invention>
As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, Various changes are possible in the range which does not deviate from the summary. For example, in the above-described embodiment, the semi-transparent film 102 and the light-shielding film 103 are formed in this order on the translucent substrate 101. However, the present invention is not limited to this embodiment, and the semi-transparent film 102 and Another film may be provided between the light shielding film 103.

100 Photomask 100b Mask blank 100c Intermediate substrate 101 Translucent substrate 102 Semi-transparent film 103 Light-shielding film 103p First resist pattern 104 First resist film 104p First resist pattern 105 Second resist film 105m Margin region 105p Second resist pattern 111 Translucent portion 112 Semi-translucent portion 113 Light shielding portion

Claims (7)

A method for manufacturing a multi-tone photomask having a transfer pattern including a light transmitting portion, a light shielding portion, and a semi-light transmitting portion,
A step of preparing a mask blank in which a semi-transparent film and a light-shielding film are formed in this order on a translucent substrate, and a first resist film is formed on the uppermost layer;
A pattern is drawn on the first resist film and developed to form a first resist pattern that covers the area where the light shielding portion is to be formed and the area where the semi-transparent portion is to be formed, and the first resist pattern The light shielding film is etched using the first resist pattern or the light shielding film pattern as a mask to form the light transmitting portion by etching the light shielding film using the first resist pattern or the light shielding film pattern as a mask. A patterning process;
Forming a second resist film covering the entire surface of the substrate obtained by removing the first resist pattern;
A pattern is drawn on the second resist film and developed to form a second resist pattern that covers a region where the light shielding portion is to be formed, and the light shielding film pattern is etched using the second resist pattern as a mask. A second patterning step of forming the semi-translucent part and the light-shielding part,
In the step of forming the second resist film, prior to the formation of the second resist film, a surface treatment with a Si-containing organic compound is performed on the surface of the translucent substrate that is exposed by forming the translucent portion. A method of manufacturing a multi-tone photomask characterized by the above. 2. The multi-storey according to claim 1, wherein the second resist pattern has a margin region that is enlarged toward the light transmitting portion at a boundary between the light shielding portion formation scheduled region and the light transmitting portion. A method for producing a photomask. The margin region covers a side surface of the translucent film and a side surface of the light-shielding film at the boundary, and covers a part of the surface of the translucent substrate in the translucent part. A method for producing a multi-tone photomask described in 1. 4. The method of manufacturing a multi-tone photomask according to claim 1, wherein etching performed in the first patterning step and the second patterning step is wet etching. 5. The light shielding film is made of chromium or a compound thereof,
5. The method for manufacturing a multi-tone photomask according to claim 1, wherein the semi-translucent film is made of molybdenum silicide or a compound thereof. 6. The method for producing a multi-tone photomask according to claim 1, wherein the Si-containing organic compound is hexamethyldisilane. 7. A method of manufacturing a semiconductor transistor, wherein the multi-tone photomask according to claim 1 is irradiated with exposure light, and the transfer pattern is transferred to a transfer target.