JP2000331913A - Pattern formation method and manufacture of semiconductor device using the same method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress pattern peeling in the periphery of materials to be exposed even at the time of exposing the whole face of the materials to be exposed by using a positive photoresist. SOLUTION: In a pattern formation method having a process for pattern exposing the whole face of a positive photoresist on a substrate, a positive photoresist 2 is formed on a substrate 1, and pattern exposure is carried out to the whole face of the substrate, and the photoresist at the outer peripheral part of the substrate is insolubilized in developer, and development is carried out. In this case, the outer peripheral part of the substrate is the unproductive area for wafer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of forming a pattern and a method of manufacturing a semiconductor device using the same. In particular, the present invention provides a pattern forming method suitable for forming a fine pattern and a manufacturing method suitable for manufacturing a semiconductor device including a step of forming a fine pattern.

[0002]

2. Description of the Related Art Pattern formation is widely performed by photolithography technology, and the demand for finer patterns in the technology is increasing more and more. For example, in recent manufacturing processes of advanced semiconductor devices, there is a strong demand for forming finer patterns with higher precision.

[0003] In general, for example, in general-purpose memory devices such as DRAMs, it is most important to improve the degree of integration of the devices to the utmost in order to produce larger-capacity memories with higher profitability. In the formation of a pattern in a photolithography process, the demand for miniaturization of processing dimensions has become extremely high technically. In response to such a demand for device design, a situation in which a positive photoresist which is advantageous in terms of resolution is used in most cases.

However, in response to the trend of miniaturization of the processing dimensions, the substantial process margin (exposure margin / focus margin, etc.) tends to be narrower, and accordingly, the stability of the resist pattern shape must be maintained. The difficulty is also very high. For example, in a region such as a wafer peripheral region where the underlying structure is unstable and it is difficult to focus during exposure, the resist pattern P as shown in FIG.
In some cases, the cross-sectional shape becomes inverse-tapered. In particular, when the pattern line width is small, the pattern tends to be easily collapsed (reference numeral 1 ′ indicates a base). This tendency is becoming more remarkable because the resist shape is designed to have a higher aspect ratio than the design due to the miniaturization of device design rules.

Further, in order to increase the uniformity of the etching conversion difference in the wafer surface in the subsequent etching process such as RIE, in order to make the pattern accuracy around the wafer uniform, as shown in FIG. There is a case where a pattern is shot (projected) up to (an area where product chips cannot be obtained). In this case, the autofocus of the stepper (projection exposure machine) normally operates for the shot 11 within the balance shown in white in FIG. The side part 12 shown by thin shading is
Although autofocus is guaranteed, in a shot of the portion 13 over the wafer edge indicated by dark shading, autofocus of the stepper (projection exposure machine) does not work well, and defocus is easily performed.

As described above, when a positive photoresist is used and the entire surface is shot up to the unacceptable partial area around the wafer, the pattern around the wafer as shown in FIG. Peeling 9 is particularly likely to occur from a portion that is cut (reference numeral 7 is the outer periphery of the wafer). If the peeled resist pattern or the underlying pattern to which the resist pattern has been transferred completely scatters from the wafer, it becomes dust, which can be a major factor in deteriorating the product yield.

The above problems are all problems when the entire surface of the material to be exposed is exposed using a positive photoresist.

[0008]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and when exposing the entire surface of a material to be exposed, suppresses peeling of a pattern around the material to be exposed. It is an object of the present invention to provide a pattern forming method that solves the problem of dust and the like, and a method for manufacturing a semiconductor device using the same.

[0009]

According to the present invention, there is provided a pattern forming method comprising the steps of: exposing a positive photoresist on a substrate to an entire surface; After pattern exposure is performed on the entire surface of the substrate, a process of insolubilizing the photoresist on the peripheral portion of the substrate with a developing solution is performed, and then development is performed.

The method of manufacturing a semiconductor device according to the present invention is a method of manufacturing a semiconductor device having a step of pattern-exposing the entire surface of a positive photoresist on a substrate. After performing pattern exposure on the entire surface, a process of insolubilizing the photoresist in the outer peripheral portion of the substrate with a developing solution is performed, and thereafter, development is performed.

According to the present invention, since a process for insolubilizing the photoresist in the peripheral portion of the substrate with the developing solution is performed, pattern peeling around the substrate can be suppressed. Therefore, even when pattern exposure is performed on the entire surface of the substrate, pattern peeling around the substrate is suppressed, dust is prevented from being generated due to the peeling, and a reduction in product yield can be prevented. Japanese Patent Application Laid-Open No. 9-32142 discloses a technique in which a protective layer is formed on the peripheral surface of a wafer to prevent the generation of foreign matter. However, this technique does not insolubilize the peripheral resist and is remarkably different from the present invention. Different.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be further described below, and preferred specific examples will be described with reference to the drawings. Needless to say, the present invention is not limited to the illustrated embodiment.

In the present invention, the process of insolubilizing the photoresist in the outer peripheral portion of the substrate in the developing solution is performed. The outer peripheral portion of the substrate for performing the process of insolubilizing the photoresist in the developing solution is a portion outside the control of the substrate. As a result, the present invention can be carried out without impairing the yield of the product. That is, for example, in the semiconductor wafer, the periphery of the element forming surface (surface) is a so-called unreasonable part which is not a target as a product. Therefore, the resist in this part is insolubilized. It can take the form.

In the present invention, a chemically amplified photoresist containing an acid generator that generates an acid by a photoreaction can be used as the positive photoresist. In this case, an excimer laser beam can be used as an exposure light source. In addition, a resist using an azide compound as a photosensitive agent can be used. For example, a positive photoresist mainly containing a novolak resin and naphthoquinonediazide can be used. In this case, a g-line or an i-line of a mercury lamp can be used as an exposure light source.

In the present invention, the process of insolubilizing the photoresist in a developing solution can be a process of developing the photoresist on the outer peripheral portion of the substrate with the developing solution. At this time, the photoresist on the outer peripheral portion of the substrate is lost. Make use of
Can be insolubilized. For example, when a chemically amplified photoresist containing an acid generator is used, a treatment for neutralizing an acid generated by light with an alkali developer to deactivate the acid can be performed. Further, a treatment can be performed such that a hardly-solubilized layer is formed on the resist surface so as to be insolubilized.

In the embodiment described below, a protective film serving as a cover film is formed on a positive photoresist in the entire wafer exposure using a positive photoresist, and after exposure, a developing solution ( For example, the protective film is peeled off with an aqueous solution of TMAH (tetramethylammonium hydroxide), which is an alkali developing solution, and is brought into contact with the surface of a lower photoresist film to be insolubilized in the developing solution. It is designed to suppress withering. Hereinafter, specific embodiments will be described.

Embodiment 1 This embodiment is directed to a semiconductor device (for example, a MOS transistor used as a general-purpose memory device with advanced miniaturization and integration) in which the present invention needs to form a miniaturized pattern. Is applied to the manufacturing method of

In this embodiment, first, a semiconductor wafer substrate is subjected to a surface treatment with HMDS vapor, and then TDUR-P which is a positive type deep UV photoresist.
015 (manufactured by Tokyo Ohka Kogyo Co., Ltd.). This positive photoresist is a chemically amplified photoresist containing an acid generator that generates an acid by a photoreaction,
In particular, the above chemically amplified photoresist contains a resin having a main chain of polyhydroxystyrene. After the application of the resist, a 3 mm resist width on the outer periphery of the wafer substrate is peeled off with a thinner liquid as an organic solvent while rotating the wafer substrate. Thereafter, baking is performed at 80 ° C. for 90 seconds, and a photoresist film is formed on the wafer substrate to a thickness of 730 n.
m. Further, as a protective film, a water-soluble and acidic type TSP-5A (manufactured by Tokyo Ohka Kogyo Co., Ltd.) was spin-coated on the photoresist film in the same manner as the photoresist, and baked at 60 ° C. for 60 seconds. A film is formed to have a thickness of 42 nm.

After the formation of the photoresist film and the protective film, K
rF excimer laser stepper NSR-2205EX1
Exposure amount 30mJ / c by 2B (manufactured by Nikon Corporation)
The entire surface of the wafer is exposed at m ² , and a predetermined mask pattern is transferred to the photoresist film as a latent image. Next, the wafer substrate is sucked and supported on a vacuum chuck, and the wafer substrate is rotated at 2000 rotations per second, as shown in FIG.
The developing solution 4 is discharged so as to hit only the region 5 mm from the edge of the wafer substrate 1. At this time, a photoresist 2 is formed on the wafer substrate 1, and a protective film 3 is further formed thereon. When the developing solution 4 is discharged as described above, the water-soluble protective film 3 is instantaneously dissolved and separated from the developing solution 3 in the portion of the outer peripheral portion of the wafer substrate 1 which is in contact with the developing solution 4 as shown in FIG. Is done. At the same time, in this portion, the acid generated from the acid generator in the resist due to the photoreaction by the pattern exposure is neutralized from the surface portion in contact with the developer 3.

The development of the resist in the peripheral portion of the wafer substrate was specifically performed as follows. The developer nozzle 5 is moved onto the wafer substrate 1 so that the developer 4 hits only a region 5 mm from the edge of the wafer substrate 1, and the developer NMD-3 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) 15 ml of 2.38 wt% TMAH aqueous solution)
/ Sec for 5 seconds. Immediately thereafter, the number of revolutions of the wafer is increased to 4000 revolutions per second, and the developing solution remaining on the photoresist is shaken off and dried.

Further, the wafer substrate is baked on a hot plate at 110 ° C. for 90 seconds to obtain a developing solution NMD-3.
(Tokyo Ohka Kogyo Co., Ltd., 2.38 wt% TMAH aqueous solution) for 60 seconds of paddle (liquid) development,
Obtain a desired resist pattern. At this time, in the outer peripheral region of the wafer substrate that has already been exposed to the developing solution, the acid in the resist near the surface has been inactivated, so that the resist is insoluble in the developing solution and the resist remains.

In the conventional method, as shown in FIG. 6, pattern peeling occurred at the outermost periphery of the wafer.
Along the outermost periphery of the wafer substrate 1, the resist insolubilized by the alkali treatment after exposure is about 2 mm
Remains in width. In FIG. 2, reference numeral 6 indicates a region of the resist insolubilized by the alkali treatment after exposure. The same applies to FIG. 3, which is an enlarged view of a part III in FIG. In FIG. 3, reference numeral 7 indicates the outer periphery of the wafer, and reference numeral 8 schematically indicates a resist pattern. Since the insolubilized resist remains along the outermost periphery of the wafer substrate 1, the resist pattern on the outer peripheral portion of the wafer substrate 1, which has a tendency to degrade in cross-sectional shape and easily fall down, The phenomenon of peeling is suppressed.

Further, the TSP-5A formed on the photoresist film as a protective film functions as an antireflection film for suppressing variations in the resist pattern line width due to the multiple interference effect of light in the photoresist film, and at the same time, performs exposure. The effect of preventing the photoresist film other than the region to be post-insolubilized from being exposed to the developer splash or the alkaline volatile matter is shown.

According to this embodiment, it is possible to suppress the peeling of the resist pattern at the outer peripheral portion of the wafer substrate without impairing the uniformity of the conversion difference in the dry etching and the unreasonableness of the product chip. Therefore, it is possible to prevent the generation of dust due to the peeling of the resist pattern and the reduction of the yield.

In this embodiment, since the protective film also functions as an anti-reflection film, the line width variation of the resist pattern due to the multiple interference effect of light in the photoresist film is reduced. Further, the photoresist film other than the region to be insolubilized after exposure is prevented from being exposed to the developer splash or the alkaline volatile matter.

Embodiment 2 In this embodiment, too, the present invention is applied to the same method of manufacturing a semiconductor device as in Embodiment 1.

In this embodiment, first, a semiconductor wafer substrate is subjected to a surface treatment using HMDS vapor, and then, a THMR-iP which is a positive type i-line photoresist is used.
3300 (manufactured by Tokyo Ohka Kogyo Co., Ltd.) is spin-coated.
This positive photoresist is a positive photoresist mainly composed of a novolak resin and naphthoquinonediazide. After the application of the resist, a 3 mm resist width on the outer periphery of the wafer substrate is peeled off with a thinner liquid as an organic solvent while rotating the wafer substrate. Then 90 ° C
For 2 minutes to form a photoresist film on the wafer substrate with a thickness of 1.19 μm. Furthermore, as a protective film, a water-soluble and acidic type AZ AQUATAR (manufactured by Clariant) is spin-coated on the photoresist film in the same manner as the photoresist, and then baked at 90 ° C. for 60 seconds to a film thickness of 63 nm. The film is formed as follows.

After the formation of the photoresist film and the protective film, i
The entire surface of the wafer is exposed with a line stepper NSR-2205i12D (manufactured by Nikon Corporation) for an exposure time of 400 sec, and a predetermined mask pattern is transferred as a latent image on the photoresist film. Next, the wafer substrate is sucked and supported on a vacuum chuck, and the wafer substrate is rotated 2000 times per second, and as shown in FIG.
The developer 4 is discharged so as to hit only the area of mm. At this time, a photoresist 2 is formed on the wafer substrate 1, and a protective film 3 is further formed thereon. When the developing solution 4 is discharged as described above, the water-soluble protective film 3 is instantaneously dissolved and separated from the developing solution 3 in the portion of the outer peripheral portion of the wafer substrate 1 which is in contact with the developing solution 4 as shown in FIG. Is done. At the same time, a thin layer that is hardly soluble in a developer is formed on the surface of the photoresist 2, which is called a surface insolubilization layer.

The development of the resist in the peripheral portion of the wafer substrate was carried out in the same manner as in the first embodiment, specifically, as follows. The developer nozzle 5 is moved onto the wafer substrate 1 such that the developer 4 hits only a region 5 mm from the edge of the wafer substrate 1.
MD-3 (Tokyo Ohka Kogyo Co., Ltd., 2.38wt% T
MAH aqueous solution) at a rate of 15 ml / sec for 5 seconds. Immediately thereafter, the number of revolutions of the wafer is increased to 4000 revolutions per second, and the developing solution remaining on the photoresist is shaken off and dried.

Further, the wafer substrate was baked on a hot plate at 110 ° C. for 60 seconds to obtain a developing solution NMD-3.
(Tokyo Ohka Kogyo Co., Ltd., 2.38 wt% TMAH aqueous solution) for 60 seconds of paddle (liquid) development,
Obtain a desired resist pattern. At this time, in the outer peripheral region of the wafer substrate already exposed to the developing solution, the wafer is baked after the formation of the surface insolubilized layer, so that it is insoluble in the developing solution and the resist remains.

In the conventional method, as shown in FIG. 6, pattern peeling has occurred at the outermost periphery of the wafer.
Along the outermost periphery of the wafer substrate 1, the resist insolubilized by the alkali treatment after exposure is about 2 mm
Remains in width. As described above with reference to FIGS. 2 and 3, also in this example, the insolubilized resist remains along the outermost periphery of the wafer substrate 1 so that the cross-sectional shape is deteriorated. The phenomenon in which the resist pattern on the outer peripheral portion of the wafer substrate 1 which tends to fall down easily comes off is suppressed.

The AZ AQUATAR formed on the photoresist film as a protective film also functions as an antireflection film for suppressing variations in the resist pattern line width due to the multiple interference effect of light in the photoresist film. This has the effect of preventing the photoresist film other than the region to be insolubilized from being exposed to the developer droplets or alkaline volatiles.

According to this embodiment, it is possible to suppress peeling of the resist pattern at the outer peripheral portion of the wafer substrate without impairing the uniformity of the conversion difference in dry etching and the unacceptable product chip. Therefore, it is possible to prevent the generation of dust due to the peeling of the resist pattern and the reduction of the yield.

In this embodiment, since the protective film also functions as an anti-reflection film, the line width variation of the resist pattern due to the multiple interference effect of light in the photoresist film is reduced. Further, the photoresist film other than the region to be insolubilized after exposure is prevented from being exposed to the developer splash or the alkaline volatile matter.

[0035]

According to the present invention, even when the entire surface of a material to be exposed is exposed using a positive type photoresist, pattern peeling at the periphery of the material to be exposed can be suppressed, and the accompanying dust can be reduced. A pattern forming method and a method for manufacturing a semiconductor device which have solved the problems and the like can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation of the embodiment of the present invention.

FIG. 3 is a diagram for explaining the operation of the embodiment of the present invention.

FIG. 4 is a diagram showing a problem of the related art.

FIG. 5 is a diagram showing a problem of the related art.

FIG. 6 is a diagram showing a problem of the related art.

[Explanation of symbols]

1 ... (semiconductor) substrate (wafer), 2 ... photoresist, 3 ... protective film, 4 ... developer.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03F 7/38 512 G03F 7/38 512

Claims (19)

[Claims] 1. A pattern forming method having a step of pattern-exposing a whole surface of a positive-type photoresist on a substrate, comprising: forming a positive-type photoresist on the substrate; Performing a process of insolubilizing the photoresist in a developing solution, and thereafter performing development. 2. The pattern forming method according to claim 1, wherein the outer peripheral portion of the substrate is a portion that is out of control. 3. The pattern forming method according to claim 1, wherein the process of insolubilizing the photoresist in a developing solution is a process of developing the photoresist on an outer peripheral portion of the substrate with a developing solution. 4. The method according to claim 1, wherein the process of insolubilizing the photoresist in a developing solution is a process of inactivating the photoresist in the outer peripheral portion of the substrate or forming a hardly soluble layer in the photoresist. The pattern forming method described in the above. 5. The process of insolubilizing the photoresist in a developing solution is a process of supplying the developing solution to the photoresist in the outer peripheral portion of the substrate along the edge of the substrate while rotating the substrate. 4. The pattern forming method according to claim 3, wherein: 6. The pattern forming method according to claim 5, wherein a process of supplying a developing solution is performed while rotating the substrate. 7. After the positive photoresist is formed on a substrate, a protective film is formed on the resist, the protective film on the outer peripheral portion of the substrate is removed, and the photoresist on the removed portion is exposed, 2. The pattern forming method according to claim 1, wherein a process of insolubilizing the photoresist in the peripheral portion of the substrate with a developing solution is performed by developing the photoresist in the portion. 8. The pattern forming method according to claim 1, wherein the process of insolubilizing the photoresist in the peripheral portion of the substrate with a developing solution is performed by using an aqueous solution of tetramethylammonium hydroxide as an alkaline aqueous solution. 9. The pattern forming method according to claim 1, wherein a chemically amplified photoresist containing an acid generator that generates an acid by a photoreaction is used as the positive photoresist. 10. The method according to claim 1, wherein the chemically amplified photoresist is a chemically amplified photoresist containing a resin having a main chain of polyhydroxystyrene, and an excimer laser beam is used as an exposure light source. The pattern forming method according to claim 9. 11. A positive photoresist comprising a novolak resin and naphthoquinonediazide as main components, and a g-line or an i-line of a mercury lamp is used as an exposure light source. The pattern forming method according to claim 1. 12. The method according to claim 11, wherein the positive photoresist is formed by
2. The pattern forming method according to claim 1, wherein after exposing the resist around the substrate, the resist is stripped with a width smaller than a width of contact with the alkaline aqueous solution. 13. A method for manufacturing a semiconductor device, comprising: a step of pattern-exposing a positive photoresist on a substrate to a whole surface, comprising: forming a positive photoresist on a semiconductor substrate; A method for manufacturing a semiconductor device, comprising: performing a process of insolubilizing a photoresist in a peripheral portion of a substrate with a developing solution, and thereafter performing development. 14. The method of manufacturing a semiconductor device according to claim 13, wherein the outer peripheral portion of the substrate is a portion that is out of control of semiconductor element formation. 15. The process of insolubilizing a photoresist in a developing solution is a process of developing a photoresist on a peripheral portion of the substrate with a developing solution.
13. The method for manufacturing a semiconductor device according to item 5. 16. The method according to claim 13, wherein the process of insolubilizing the photoresist in a developing solution is a process of inactivating the photoresist in the outer peripheral portion of the substrate or forming a hardly soluble layer in the photoresist. The manufacturing method of the semiconductor device described in the above. 17. The method of insolubilizing a photoresist in a developer, comprising:
16. The method of manufacturing a semiconductor device according to claim 15, wherein the processing includes supplying a developing solution to a photoresist at an outer peripheral portion of the substrate along the edge of the substrate while rotating the substrate. 18. The pattern forming method according to claim 17, wherein a process of supplying a developing solution is performed while rotating the substrate. 19. After forming the positive photoresist on a substrate, forming a protective film on the resist, removing the protective film on the outer peripheral portion of the substrate, exposing the photoresist on the removed portion, 14. The method of manufacturing a semiconductor device according to claim 13, wherein a process of insolubilizing the photoresist in a peripheral portion of the substrate with a developing solution is performed by developing the photoresist in the portion.