JP3017776B2 - Pattern formation method - Google Patents

Description

The present invention relates to a lithography step in a method for manufacturing a semiconductor device, and more particularly to a method for forming a pattern.

(Prior Art) Recent progress in semiconductor technology has been remarkable, and with the progress of these technologies, higher speed and higher integration of semiconductor devices have been promoted. Along with this, the necessity of miniaturization of circuit patterns has been increasing, and high-precision pattern formation has been required.

At present, a method of processing an underlying semiconductor substrate on which elements and the like are formed by RIE (reactive ion etching) using a resist pattern as a mask is used in a pattern forming process.

Therefore, in order to form a fine circuit pattern, it is required to form a fine resist pattern with a high aspect ratio and high dimensional accuracy.

The resist pattern forming process includes a single-layer resist process and a multi-layer resist process.

The former single-layer resist process is a method in which one resist layer is provided on a semiconductor substrate on which elements and the like are formed, and is patterned by exposing and developing to form a resist pattern. By the way, in general, there are steps on the surface of a semiconductor substrate on which elements and the like are formed. In order to flatten this step, it is necessary to form a resist layer having a certain thickness (1 μm or more). However, when the thickness of the resist layer increases, it is difficult to secure a depth of focus in the resist layer. . In addition, when the exposure light is absorbed by the resist layer and the thickness of the resist layer increases, the light intensity at the bottom of the resist layer decreases according to Lambert's law, which causes a problem that the resolution is deteriorated.

As a technique for solving this problem, there is a multilayer resist process. This multilayer resist process is a method of forming a resist pattern in which a plurality of resist layers are provided on a semiconductor substrate on which elements and the like are formed, and a pattern formed on an uppermost layer is patterned in order from the top.

For example, in a three-layer resist process, two
After forming a flattening layer having a thickness of about 3 μm and flattening a step on the surface of the semiconductor substrate, an intermediate layer, for example, a SOG (Spin on glass) layer is formed on the flattening layer, and further, an exposure light is formed thereon. To form a photosensitive resin layer having good sensitivity. Thereafter, by pattern exposure, the photosensitive resin layer is patterned,
Using this as a mask, the pattern is transferred to the intermediate layer by anisotropic etching using a gas containing fluorine atoms or the like. Further, using the pattern of the intermediate layer as a mask, anisotropic etching using oxygen gas is performed to form a pattern.

In this three-layer resist process, the step of the surface of the semiconductor substrate is flattened by a lower flattening layer, and the upper and lower resist layers are separated by an intermediate layer. There is only patterning. As described above, when the film thickness of the resist layer (in this case, the photosensitive resin layer) increases, the depth of focus and the resolution are problematic. Therefore, the photosensitive resin layer is often formed to be thin.

However, reducing the thickness of the photosensitive resin layer causes the following problem. That is, when developing a thinned photosensitive resin layer, the development time is shortened and the margin for the development time is reduced, so that the thickness and dimensions of the photosensitive resin layer developed within the same wafer surface and between different wafers Variations in accuracy will increase. In addition, there arises a problem that the resistance to a subsequent etching process is deteriorated due to the thin film.

Therefore, it is necessary to suppress a decrease in the film thickness of the pattern. For example, there is a method of insolubilizing the surface with a developing solution. FIG. 10 is a process cross-sectional view for explaining the surface insolubilization method.

In this surface insolubilization method, a photosensitive resin layer is first placed on the substrate 91.
After forming 92 (FIG. 10 (a)), the surface of the resin layer 92 is exposed to an organic alkali developer (FIG. 10 (b)). At this time, since the resin contained in the photosensitive resin layer 92 is soluble in the organic alkali developing solution, it is eluted in the alkali developing solution, and the surface portion 92a of the resin layer 92 is reduced in film thickness. The photosensitive agent contained in the resin 92 condenses on the surface of the resin layer 92. This photosensitive agent is generally hardly soluble in an alkali developer, and a hardly soluble layer 93 is formed on the surface of the resin layer 92.

Note that this hardly soluble layer 93 is 800 μm from the surface of the photosensitive resin layer 92.
It is formed in the following region, and the inside of the resin layer 92 is not different from a normal photosensitive resin layer. Next, the radiation 95 is passed through the mask 94.
And the irradiated portion 96 changes to a solubilized layer (FIG. 10 (c)). Further, in order to change the irradiated portion 96 into a solubilized layer, an exposure amount larger than a normal exposure amount is required, so that exposure blur occurs near the exposed portion below the remaining hardly soluble layer 93. A dotted line 97 is a boundary line between an exposed portion and a non-exposed portion inside the resin layer 93. Therefore, when the resin layer 93 is developed, the hardly-solubilized layer 93 on the surface is very stable to the developing solution and hardly undergoes film reduction. At this time, the hardly-solubilized layer 93 on the surface of the non-exposed portion is not developed, but the vicinity of the exposed portion below the portion is blurred as described above, so that it gradually dissolves in the developer penetrating from the exposed portion, As a result, the development easily proceeds to the boundary line 97. Therefore, as the development proceeds, the development proceeds in the horizontal direction below the hardly-solubilized layer 93, and as a result, the shape of the pattern becomes a state in which the upper portion has an eave, and the shape is deteriorated (FIG. 10 (d)). .

(Problems to be Solved by the Invention) As described above, in the multilayer resist process,
In order to increase the depth of focus and increase the resolution, the photosensitive resin layer is often formed as a thin film, but when developing a photosensitive resin layer thinned by a conventional process, the time required for development is shortened and the development time is reduced. Therefore, there is a problem that the variation in the thickness and the dimensional accuracy of the photosensitive resin layer becomes large within the same wafer surface and between different wafers.

To cope with such a problem, a surface insolubilization method is known as a method of suppressing a decrease in the thickness of the pattern, but the insolubilized layer is formed only on the surface of the photosensitive resin layer,
When development is performed, a pattern having a shape with an eaves on the upper portion is generated, and the overall pattern shape is deteriorated.

The present invention has been made in view of the above circumstances, and has as its object to provide a pattern forming method which solves the above-mentioned problem.

[Configuration of the invention]

(Means for Solving the Problems) In order to solve the above-mentioned problems, a first invention of the present application comprises a step of forming a thin film of a photosensitive resin on a substrate, and the step of forming a thin film of the photosensitive resin on an alkaline developer. Forming a photosensitive resin pattern by exposing the entire photosensitive resin thin film to alkali insolubilization, pattern exposure of the insolubilized photosensitive resin thin film, and subsequent development. A step of irradiating radiation to a surface portion of the photosensitive resin thin film including the pattern forming region, and a step of selectively forming a deposition layer on the pattern by graft polymerization. A method for forming a pattern is provided.

The second invention of the present application also includes a step of forming a thin film of a photosensitive resin on a substrate, a step of pattern-exposing the thin film of the photosensitive resin, and thereafter, a step of forming a thin film of 2.15% or less containing tetramethylammonium hydroxide as a main component. Developing with an organic alkali developer having a concentration of 2.38% or an organic alkali developer having a concentration of 2.57% to 3.15% containing choline as a main component to form a pattern of a photosensitive resin; And selectively forming a deposited layer by graft polymerization.

(Function) According to the first aspect of the present invention, a photosensitive resin thin film is formed on a substrate, and the entire thin film is hardly alkali-soluble by exposing the surface of the thin film to an alkali developing solution. Since the thin film is subjected to pattern exposure and then developed to process the thin film into a pattern, a highly accurate thin film pattern can be formed. Further, the time required for development can be lengthened, and the margin for the development time can be increased. Accordingly, there is no variation in the thickness and dimensional accuracy of the photosensitive resin layer within the same wafer surface and between different wafers. Thereafter, by selectively forming a deposited layer on the thin film pattern by graft polymerization, a pattern having sufficient resistance to a subsequent etching step and excellent dimensional accuracy can be formed.

According to the second aspect of the present invention, a photosensitive resin thin film is formed on a substrate, the photosensitive resin thin film is subjected to pattern exposure, and then the pattern-exposed photosensitive film is exposed using a relatively low-concentration developer. Since the resin thin film is developed and processed into a pattern, a margin for the development time can be increased, and a pattern with excellent dimensional accuracy having sufficient etching resistance is formed. By forming the deposited layer, a pattern having more sufficient etching resistance can be formed.

(Example) Hereinafter, an example of a pattern forming method according to the present invention will be described in detail with reference to the drawings.

First Embodiment FIG. 1 is a process sectional view showing an embodiment of the first invention of the present application. A silicon substrate 1 is spin-coated with a g-line positive photoresist having a novolak resin and a naphthoquinonediazide derivative as a photosensitizer, and baked at 200 ° C. for 30 minutes to form a 2.0 μm-thick planarization layer 2. did.
Next, SOG is spin-coated on the flattening layer 2 at 200 ° C.
The intermediate layer 3 having a thickness of 0.2 μm was baked for 15 minutes. Further, a positive photoresist for g-line was applied on the intermediate layer 3 at a thickness of 1000 ° to form a photosensitive resin layer 4 (FIG. 1A).

Next, the photosensitive resin layer 4 was exposed to an alkali developing solution containing 2.38% of tetramethylammonium hydroxide (TMAH) for 30 seconds. At this time, the surface area of the photosensitive resin layer 4
4a is eluted at 400 、, and the remaining thickness of the photosensitive resin layer 4 is 600 Å
And the whole became a hardly-solubilized layer (4b) (FIG. 1 (b)).

Next, a g-line (wavelength 436 nm)
m) was irradiated at an exposure energy of 200 mJ / cm ² (FIG. 1 (c)). Reference numeral 7 denotes an irradiation area. Next, the surface of the photosensitive resin layer 4b is subjected to dip development for 30 seconds using a 2.38% developer (organic alkali developer) of tetramethylammonium hydroxide (TMAH) to form a photosensitive resin pattern 4c. (FIG. 1 (d)). At this time, the linearity of the pattern dimension is within ± 10% of the mask dimension.
A pattern of 0.35 μm was obtained. For comparison, a pattern was formed under the same conditions except that the thickness of the photosensitive resin layer was increased to 1.5 μm.
It was confirmed that the height increased by 15 μm. When the photosensitive resin layer is exposed to an alkali developing solution and its thickness is set to 800 mm or less as in this example, the entire photosensitive resin layer becomes a hardly soluble layer, and no eaves are formed on the upper portion of the pattern during development, and Since the film loss is suppressed, the margin for the development time also increases.

In the case of extremely thin etching of the base, it can be used as a mask, but it is usually desirable to perform the following steps. That is, the substrate 1 on which the pattern 4c was formed was placed in a chamber (not shown) that can be evacuated, and while this chamber was evacuated, the styrene monomer was introduced into the chamber in a gaseous state.

Next, while irradiating the entire surface with a Xe-Hg lamp 8, the styrene monomer was selectively graft-polymerized on the photosensitive resin pattern 4b to form a graft polymerization layer 9 (FIG. 1 (e)). At this time, the line and space of the polymer layer 9 was maintained at 0.35 μm as described above, and the film thickness was increased to 0.5 μm by the polymer layer 9, and the film thickness was sufficient for etching resistance.

Next, using the polymerized layer 9 as a mask, the intermediate layer 3 and the planarizing layer 2 are used.
Was sequentially anisotropically etched to form a multilayer resist pattern.

As a result, a multilayer resist pattern having an improved pattern shape has been obtained.

Second Embodiment Next, a second embodiment of the pattern forming method according to the first invention of the present application will be described.
Will be described with reference to FIG.

First, a positive photoresist for g-line containing a novolak resin and naphthoquinonediazide (photosensitizer) is spin-coated on a silicon substrate 1 and baked at 200 ° C. for 30 minutes to form a planarization layer 2 having a thickness of 1.6 μm. Was formed. SOG is spin-coated on the flattening layer 2 and baked at 200 ° C. for 15 minutes to form an intermediate layer 3 having a thickness of 0.1 μm.
On this intermediate layer 3, PR1024 manufactured by MacDamide Co.
To form a photosensitive resin layer 4 (FIG. 1A).

Next, the photosensitive resin layer 4 is exposed to a 2.38% developing solution of tetramethylammonium hydroxide (TMAH) for 30 seconds to make the thickness of the photosensitive resin layer 4 420 mm and to make the entire photosensitive resin layer 4 hardly soluble. This was a layer 4b (FIG. 1 (b)). Next, a mask 5 is applied to the photosensitive resin layer 4.
Is exposed to light 6 having a wavelength of 248 nm of a KrF excimer laser as the exposure light 6 (FIG. 1 (c)).
A pattern 4c having a line and space of μm was obtained with high precision (FIG. 1 (d)). Further, a styrene monomer was graft-polymerized on the photosensitive resin pattern 4c in the same manner as in the first embodiment (FIG. 1 (e)), and etching was performed to form a resist pattern.

According to this embodiment also, a multilayer resist pattern having an improved pattern shape can be obtained.

Third Embodiment FIG. 2 is a process sectional view showing a third embodiment of the pattern forming method according to the first invention of the present application. In the following drawings, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description will be omitted.

First, a flattening layer 2 and an intermediate layer (SOG layer) 3 are formed on a silicon substrate 1 in the same manner as in the first and second embodiments. layer
21 was formed (FIG. 2 (a)).

Next, radiation 22 is applied to the entire surface of the photosensitive resin layer 21.
G light from a mercury lamp was applied at an exposure energy of 45 mJ / cm ² (FIG. 2 (b)). Here, 21a indicates a g-ray irradiation area, which is formed on the surface of the photosensitive resin layer 21. Next, the surface of the photosensitive resin layer 21 was exposed to a developer of tetramethylammonium hydroxide (TMAH) 2.38% for 30 seconds. At this time, the photosensitive resin layer 21 has 55
The portion (21b) within 0 ° was eluted, the thickness of the photosensitive resin layer 21 became 650 °, and the entire layer became the hardly soluble layer 21c (FIG. 2 (c)).

As in this example, when the surface of the photosensitive resin layer 21 is weakly irradiated with radiation 22 such as g-ray before exposure to the organic alkali developer, the photosensitive agent exposed at the stage of exposure to the organic alkali developer becomes The resin around the exposed photosensitive agent is also eluted. Further, most of the unsensitized photosensitive agent condenses on the surface. As a result, the resin on the surface of the photosensitive resin layer 21 is less soluble in the organic alkali developing solution than in the case where the photosensitive resin layer 21 is not exposed to radiation and is simply exposed to the organic alkali developing solution. The photosensitive agent that is hardly soluble in the liquid is more condensed, and a stronger hardly soluble layer is formed.

Next, as exposure light 6, a g-line of a mercury lamp is used as a mask 5.
With an exposure energy of 550 mJ / cm ² (second
Figure (d). Further, a 2.38% developing solution of tetramethylammonium hydroxide (TMAH) was exposed to the surface of the photosensitive resin layer 21c to perform dip development for 30 seconds to form a photosensitive resin pattern 21d (FIG. 2 (e)). The linearity of the pattern size is 0.
A pattern of up to 35 μm was obtained, and the thickness of the photosensitive resin layer was 1.
It was confirmed that the resolution was increased by 0.15 μm as compared with the case where patterning was performed under the same conditions except that the thickness was set to 5 μm. Thereafter, a styrene monomer was selectively graft-polymerized on the pattern 21d in the same manner as in the previous example, and a multilayer resist pattern could be formed with almost the same precision through an etching step (FIG. 2 (f)).

Next, the effect of the embodiment of the present invention will be described with reference to FIG. That is, in the figure, the horizontal axis represents the exposure time as a measure of the amount of exposure, and the vertical axis represents the thickness (d ₁ ) of the initial (undeveloped) photosensitive resin layer after the development with respect to the thickness (d ₀ ) of the photosensitive resin layer. Conventional development processing when the ratio (relative film thickness) is taken (と),
Characteristic diagrams of the organic alkali developer treatment (△) of the first and second embodiments of the present application and the characteristic diagram of the third embodiment (radiation irradiation before treatment with the organic alkali developer (□)) of the third embodiment are shown. Here, the development time after exposure was fixed.

Focusing on the slope (referred to as γ value) of a portion showing a steep fall of the relative film thickness when the exposure amount (time) is increased in FIG.
4 and 14.9, which are larger than and extremely larger than.

The greater the γ value, the greater the difference in relative film thickness between the exposed and unexposed areas for a given exposure. That is, the exposed portion is more easily developed, and the non-exposed portion is more difficult to be developed. Therefore, the obtained pattern is a pattern having a good shape with the side walls raised.
It can be seen that Example (□) is extremely excellent. Further, it was found that even in the case of the first and second embodiments (本 願) of the present application, the improvement was achieved as compared with the conventional case (○).

Fourth Embodiment FIG. 4 is a process sectional view showing a fourth embodiment of the pattern forming method according to the first invention of the present application.

First, after forming a planarizing layer 2 and an intermediate layer 3 (SOG layer) on a silicon substrate 1 in the same manner as in the first embodiment, a positive resist for g-line is applied in a thickness of 1200 ° to form a photosensitive resin layer 31. Is formed (FIG. 4A). Next, using a mask 32, the mercury lamp g is applied to the pattern formation region 31a of the photosensitive resin layer 31.
Line 33 was irradiated at an exposure energy of 45 mJ / cm ² (FIG. 4 (b)). This makes it possible to form a strong hardly-solubilized layer as in the above-described embodiment.

Next, the surface of the photosensitive resin layer 31 was exposed to a developer of 2.38% of tetraammonium hydroxide (TMAH) for 30 seconds. At this time, a portion corresponding to 31b of the photosensitive resin layer 31 was eluted. That is, 600 ° was eluted in the pattern forming region and the entire region was hardly dissolved, while 200 ° was eluted outside the pattern forming region. As a result, as shown in the photosensitive resin layer 31c, a shape protruding outside the pattern formation region is obtained (FIG. 4 (c)).

Next, g-rays from a mercury lamp were irradiated as exposure light 6 through a mask 5 at an exposure energy of 550 mJ / cm ² . In addition, tetramethylammonium hydroxide (TM
AH) Exposing the surface of the photosensitive resin layer 31c to a 2.38% developer,
Dip development was performed for 0 second to form a pattern 31d. The linearity of the pattern dimension was obtained up to a pattern of 0.35 μm with an accuracy of ± 10% of the mask dimension, and it was confirmed that the resolution was increased by 0.15 μm as compared with the case where the thickness of the photosensitive resin layer was 1.5 μm. . Thereafter, a styrene monomer was graft-polymerized on the pattern 31c, and a resist pattern could be formed with the same precision through an etching process.

Further, the pattern obtained in this example had a better shape standing on the side wall as compared with the patterns obtained in the first and second examples as in the third example. .

Fifth Embodiment FIG. 5 is a process sectional view showing a fifth embodiment of the pattern forming method according to the first invention of the present application.

A silicon oxide film 42 is formed on a silicon substrate 41 to a thickness of 1000 、, and a positive photoresist for g-line is applied thereon to a thickness of 800 を to form a photosensitive resin layer 43 (fifth embodiment).
Figure (a).

Next, the photosensitive resin layer 43 was exposed to a 2.38% tetramethylammonium hydroxide (TMAH) developer for 30 seconds to elute the surface portion 43a, and the entire layer was made a hardly soluble layer 43b (fifth embodiment).
Figure (b). At this time, the thickness of the photosensitive resin layer was 350 °. Further, the insolubilized photosensitive resin film 43b is irradiated with a g-ray of a mercury lamp through a mask 5 through a mask 5 (FIG. 5 (c)), and developed to accurately form a 0.35 μm line and space pattern 43c. It was well obtained (Fig. 5 (d)). Thereafter, a styrene monomer was graft-polymerized on the pattern 43c, and a resist pattern was formed with the same precision (FIG. 5 (e)).

In the above-described first to fifth embodiments, when a positive resist for i-line is used for the photosensitive resin layer and i-line (wavelength 365 nm) of a mercury lamp is used for the entire surface exposure and pattern exposure, In each case, the linearity of the pattern dimension was obtained up to a pattern of 0.30 μm with an accuracy of the mask dimension ± 10%. In addition, in any case of the g-line photosensitive resin layer and the i-line photosensitive resin layer, the entire surface can be exposed using light having a wavelength of 300 nm or more of a mercury lamp. The effect was obtained.

Sixth Embodiment An embodiment of a pattern forming method according to the second invention of the present application will be described below.

FIG. 6 is a process sectional view for explaining one embodiment of the pattern forming method according to the second invention of the present application. First, a positive resist (manufactured by Tokyo Ohka Kogyo Co., Ltd.) on a silicon substrate 61
Was spin-coated at 3000 rpm and baked at 180 ° C. for 20 minutes to form a planarization layer 62 having a thickness of 2.0 μm. Next, SOG was applied on the flattening layer 62, baked at 200 ° C. for 15 minutes, and changed to silicon oxide to form an intermediate layer 63. Further, a positive resist for i-line (manufactured by Nippon Synthetic Rubber Co.) was spin-coated at 4000 rpm on the intermediate layer 63 and baked at 90 ° C. to form a photosensitive resin layer 64 having a thickness of 0.5 μm (No. FIG. 6 (a).

Next, as shown in FIG.
Was irradiated with i-rays from a mercury lamp as exposure light 6 through a mask 5. Here, 7 indicates an irradiation area. Next, as shown in FIG. 6 (c), using a low-concentration organic alkali developer containing 2.24% of tetramethylammonium hydroxide (TMAH), development was performed for 45 seconds by a paddle method, and the side wall was vertically extended. Close photosensitive resin layer pattern
64 was formed with a 0.35 μm line and space.

The combination of the developer concentration and the development time was 2.31%
Also, good patterns with high dimensional accuracy could be obtained at 38 sec, 2.38% and 30 sec. Furthermore, a good pattern could be obtained even when the concentration of tetramethylammonium hydroxide (TMAH) was set at 2.15% to 2.24%. In this embodiment, the temperature of the developer is 23 ° C.
And

The developer concentration and the developing time of the embodiment of the second invention of the present application are as follows.
It was set based on the characteristic diagram of FIG. In other words, in this drawing, the range indicated by the hatching, that is, the developer concentration of 2.15% to 2.38% indicates an appropriate concentration that can expand the margin for the development time. In other words, if the developer concentration is 2.15% or less, the application time is too long, or the concentration is too low, so that the development selectivity of the exposed part and the non-exposed part is reduced and the pattern shape is deteriorated. all right. Therefore, the shaded portion in FIG. 7 is the applicable range of the embodiment of the second invention of the present application.

FIG. 8 shows the relationship between the optimum developing time at a certain density and the γ value in this embodiment. As can be seen from this figure, high γ values were shown in the order of the developer concentration of 2.24%, 2.31%, and 2.38%. Moreover, the pattern shape was good in this order. When the developer concentration is 2.24%, the development time is 45 seconds, at 2.31% 38 seconds, and at 2.38% 30 seconds, the maximum value of the γ value is given. A development margin of about ± 12% was confirmed around this development time. The maximum value of the γ value at each density increases as the density decreases, and the development time corresponding to the maximum value decreases as the density increases. Further, the maximum value at each concentration is shifted substantially on a straight line.

As a result of the above examination, the developer concentration was 2.15% to 2.
It is effective to set 38%, more preferably in the range of 2.24% to 2.38%, and the developing time is 2.24%
At 45 seconds, the maximum was 38 seconds at 2.31%, and 30 seconds at 2.38%.

As described above, according to the second embodiment of the present invention, by making the developer concentration lower than usual, the developing speed of the photosensitive resin layer is reduced, and the time required for the development can be extended. A large margin for time can be taken, and a pattern with excellent dimensional accuracy can be formed. Further, the film thickness of the pattern is sufficiently large and the etching resistance is sufficient.

The developing conditions described above are almost the same for the g-line resists of the first to fifth embodiments described above, and can be applied to these embodiments.

Seventh Embodiment FIG. 9 is a process sectional view showing another embodiment of the pattern forming method according to the second invention of the present application. The developing time and the developer concentration were the same as in the sixth embodiment.

First, as shown in FIG. 9 (a), a multilayer resist layer composed of a planarizing layer 62, an intermediate layer 63 and a photosensitive resin layer 71 was formed in this order on a silicon substrate 61 in the same manner as in the sixth embodiment. .

Next, the surface of the photosensitive resin layer 71 is immersed in an organic alkali developing solution containing 2.38% of tetramethylammonium hydroxide (TMAH) for 30 seconds and washed with water to obtain a photosensitive resin layer as shown in FIG. 9 (b). The hardly soluble layer 71a was formed on the surface of the conductive resin layer 71. At this time, the photosensitive resin layer 71 was reduced in film thickness due to elution of the surface portion 71b, and became the hardly soluble layer 71c.

Next, as shown in FIG. 9 (c), after pattern irradiation of i-line of a mercury lamp as the exposure light 6 through the mask 5,
Tetramethylammonium hydroxide (TMAH)
By developing the surface of the photosensitive resin layer 71c by a paddle method using an organic alkali developer containing 2.24% for 45 seconds, a pattern 71c in which a non-exposed portion remains is formed as shown in FIG. 9 (d). did. In this case, because of the hardly soluble layer 71a,
The film thickness of the photosensitive resin pattern 71c was prevented from being reduced, and a better pattern having a pattern size of 0.35 μm was obtained. In this example, the combination of the developer concentration and the developing time was 2.31% and 38 sec, and 2.38%.
And a good pattern could be obtained for 30 sec.
A good pattern could be obtained even when the concentration of tetramethylammonium hydroxide (TMAH) was set at 2.15% to 2.24%.

Eighth Embodiment Next, another embodiment of the pattern forming method according to the second invention will be described with reference to FIG.

As in the sixth embodiment, a planarization 6
2. After forming a multilayer resist layer composed of the intermediate layer 63 and the photosensitive resin layer 64 (FIG. 6A), i-line of a mercury lamp is subjected to pattern exposure (FIG. 6B). Baking is performed at 110 ° C. for 2 minutes in order to reduce shape deterioration due to standing waves.
Next, tetramethylammonium hydroxide (TM
AH) A pattern having a good shape could be obtained by developing with a 2.24% organic alkali developer for 45 seconds (No. 6).
Figure (c). A good pattern could be obtained even when the combination of the developer concentration and the developing time were set to 2.31% and 38 sec, 2.38% and 30 sec. A good pattern could be obtained even when the concentration of tetramethylammonium hydroxide (TMAH) was set at 2.15% to 2.24%.

Ninth Embodiment Next, still another embodiment of the pattern forming method according to the second invention of the present application will be described with reference to FIGS.

As in the sixth embodiment, a planarizing layer is formed on a silicon substrate 61.
After forming a multi-layer resist layer comprising 62, an intermediate layer 63 and a photosensitive resin layer 64 (FIG. 6 (a)), the i-line of a mercury lamp was subjected to pattern exposure (FIG. 6 (b)). Then choline 2.95%
By performing development for 45 seconds with the organic alkaline developer containing the composition, a good pattern having a pattern size of 0.35 μm could be obtained (FIG. 6 (c)). Under the conditions of this embodiment, as in the seventh embodiment, 30 sec.
c By immersion and washing with water (FIG. 9 (b)), a good pattern with little film loss of the pattern could be obtained. Also, as in the eighth embodiment, after the i-line exposure,
Baking for 2 minutes to obtain a good pattern. Further, in the case of a developer containing choline as in this example, when the concentration of choline was set at 2.57% to 3.15%, a good pattern could be obtained.

It should be noted that the present invention is not limited to the above-described embodiment, and can be implemented with various modifications without departing from the scope of the claims.

〔The invention's effect〕

As described above, according to the pattern forming method of the present invention, a margin for the development time can be increased, and a pattern having sufficient etching resistance and excellent dimensional accuracy can be formed.

[Brief description of the drawings]

FIG. 1 is a process sectional view showing an embodiment of a pattern forming method according to the first invention of the present application, and FIGS. 2, 4 and 5 show another embodiment of a pattern forming method according to the first invention of the present application. FIG. 3 is a process sectional view showing an example, FIG.
FIG. 7 is a sectional view showing a step of an embodiment of a pattern forming method according to the second invention of the present application. FIG. 7 is a graph showing the relationship between the developer concentration and the optimum developing time at the concentration in the embodiment of FIG. FIG. 8 is a characteristic diagram showing the relationship between the optimum developing time at the developer concentration and the γ value in the embodiment of FIG. 6, and FIG. 9 is a pattern forming method according to the second invention of the present application. FIG. 10 is a process cross-sectional view showing another example, and FIG. 10 is a process cross-sectional view for explaining a conventional surface insolubilization method. 1,41,61 …… Silicon substrate, 2,62 …… Planarization layer, 3,63…
… Intermediate layer, 4,21,31,43,64,71,92 …… Photosensitive resin layer, 4a,
21b, 31b, 43a, 71b ... surface layer (elution layer) of photosensitive resin layer 4, 4b, 21c, 31c, 43b ... hardly soluble layer, 4c, 21d, 31d, 43c, 7
1c …… Photosensitive resin pattern, 5,32,94 …… Mask, 6,33
Exposure light, 7, 21a, 96 Irradiation area, 8 Xe-Hg lamp, 9 Graft polymer layer, 22, 95 Radiation, 31a pattern formation area, 42 Silicon oxide film, 71a Reference numeral 93 denotes a hardly soluble layer, 91 denotes a substrate, 92a denotes a surface portion of the photosensitive resin layer 92, and 97 denotes a boundary between an exposed portion and a non-exposed portion.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/027 G03F 7/32 G03F 6/38

Claims (3)

(57) [Claims] 1. A step of forming a photosensitive resin thin film on a substrate, and a step of exposing the surface of the photosensitive resin thin film to an alkali developing solution to make the entire photosensitive resin thin film hardly alkali-soluble. And a step of pattern exposure of the insoluble photosensitive resin thin film, a step of forming a photosensitive resin pattern by subsequent development, and a surface portion of the photosensitive resin thin film including the pattern forming region A method for forming a pattern, comprising: irradiating radiation; and selectively forming a deposited layer on the pattern by graft polymerization. 2. The photosensitive resin thin film at the time of development has a thickness of 80
2. The pattern forming method according to claim 1, wherein the angle is set to 0 [deg.] Or less. 3. A step of forming a photosensitive resin thin film on a substrate, a step of pattern-exposing the photosensitive resin thin film, and
Thereafter, development is carried out with an organic alkali developer having a concentration of 2.15% to 2.38% mainly containing tetramethylammonium hydroxide or an organic alkali developer having a concentration of 2.57% to 3.15% mainly containing choline. A pattern forming method, comprising: forming a resin pattern; and selectively forming a deposited layer on the formed pattern by graft polymerization.