JP2001033983A - Pattern forming method, production of semiconductor device using same, and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a fine pattern that exceeds a limit due to the wavelength of light for exposure. SOLUTION: A negative type resist film is exposed and developed to form a 1st negative type resist pattern 6a and the surface part of the 1st negative type resist pattern 6a is dissolved and removed with a removing solution to stably form a 2nd resist pattern 8. This 2nd resist pattern 8 is the objective fine pattern that exceeds a limit due to the wavelength of light for exposure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a fine pattern, a method for manufacturing a semiconductor device using the same, and a semiconductor device. More specifically, the present invention relates to a method for forming a negative resist pattern in fine processing of an LSI semiconductor element, a liquid crystal display panel, a printed circuit board, and the like, and to a method for forming a fine negative resist pattern with high precision.

[0002]

2. Description of the Related Art FIGS. 9A to 9C are explanatory views showing a conventional method of forming a resist pattern by photolithography in the order of steps.
3 is a step due to wiring or the like, 4 is a chemically amplified negative resist film, 5 is a photomask, 5a is an opening thereof, 6b, 6c.
Is a resist pattern.

First, a chemically amplified negative resist film 4 for excimer is deposited on a semiconductor substrate 2 on which a step 3 is formed.
It is provided with a film thickness of 0 to 20000% (FIG. 9A). Before applying the negative resist, the surface of the semiconductor substrate 2 on which the step 3 is formed may be treated with hexamethylene disilazane or the like to enhance the adhesion with the resist film 4. Further, an upper layer material may be applied on the resist film 4.
Further, heat treatment may be performed after the application.

Next, a photomask 5 (a line width of 0.75 μm in the case of 5: 1 reduction projection exposure) adjusted so as to obtain a pattern having a line width of 0.15 μm (corresponding to the opening 5 a) is used. Using chemically amplified negative resist film 4 for excimer
Is selectively irradiated with KrF as exposure light toward
(B)｝. The exposure is performed by focusing on the lower part of the step 3 on the semiconductor substrate 2.

Next, a developing process is performed to obtain a resist pattern 6b of 0.15 μm on the semiconductor substrate 2 and a resist pattern 6c of 0.20 μm on the step 3.

[0006]

As described above, in the conventional pattern forming method, 0.15
μm resist pattern 6b is 0.20 on step 3.
A resist pattern 6c of μm was obtained, and as shown in the publication (Resist Material Handbook for Semiconductor Integrated Circuits, 1996, Realize, p. 278), the line width of the pattern was determined by the defocus dependency of the resist pattern. Fluctuated.

That is, as shown in the above-mentioned conventional method for forming a resist pattern, when a negative resist pattern is formed by exposing at an optimum focus by a stepper, a resist pattern having a line width larger than the light source wavelength of the stepper and the light source wavelength are formed. With the following fine line width resist pattern,
A resist pattern can be formed almost faithfully to the pattern of the photomask. However, in the case where a negative resist pattern is formed by exposing in a state where the focus is shifted by a stepper, a resist pattern having a line width larger than the light source wavelength of the stepper can obtain dimensions almost faithful to the photomask pattern without any problem. However, a resist pattern having a fine line width equal to or less than the wavelength of the light source has a problem in that the dimensional fluctuation is large and a desired dimension cannot be obtained. In other words, with the conventional photolithography technology using exposure,
It has been difficult to stably form a fine resist pattern exceeding the limit of the exposure wavelength.

The present invention has been made to solve such a problem, and has as its object to obtain a pattern forming method capable of forming a pattern exceeding an exposure wavelength limit. Another object of the present invention is to provide a method for manufacturing a semiconductor device having a fine pattern and a semiconductor device by using the above-described pattern forming method.

[0009]

According to a first pattern forming method of the present invention, a negative resist film is exposed and developed to form a first negative resist pattern. Is partially removed to form a second negative resist pattern.

[0010] A second pattern forming method according to the present invention comprises:
In the above first pattern forming method, a second negative resist pattern is formed by dissolving and removing the surface of the first negative resist pattern with a stripping solution.

A third pattern forming method according to the present invention comprises:
In the first or second pattern formation method, the negative resist is a method of a chemically amplified negative resist.

A fourth pattern forming method according to the present invention comprises:
In the above-mentioned third pattern forming method, the chemically amplified negative resist is a method of forming an acidic film by a residual phenolic hydroxyl group.

A fifth pattern forming method according to the present invention comprises:
In any of the second to fourth pattern forming methods, the stripping solution is a basic stripping solution.

A sixth pattern forming method according to the present invention comprises:
In the fifth pattern forming method, the basic stripping solution is a solution of an amino compound, an imino compound, a hydroxide, a pyridine base or a basic compound which is a salt of these compounds in an aqueous solution, an organic solvent, or a mixture of an organic solvent and water. This is a method of adding to a mixed solvent.

According to a seventh pattern forming method of the present invention,
In the sixth pattern forming method, the basic stripping solution is a method in which a basic aqueous solution containing tetramethylammonium hydroxide or an alcohol is added to the basic aqueous solution.

According to an eighth pattern forming method of the present invention,
In the sixth or seventh pattern forming method, a method of adjusting the concentration of the basic compound to control the amount of dissolved and removed.

According to a ninth pattern forming method of the present invention,
In any one of the second to fourth pattern forming methods, the stripping solution is an organic solvent or a mixed solvent of water and an organic solvent.

A tenth pattern forming method according to the present invention is the sixth or ninth pattern forming method, wherein
This is a method of adjusting the mixing ratio of water and the organic solvent to control the amount of dissolution and removal.

An eleventh pattern forming method according to the present invention is the first pattern forming method, wherein the first negative resist pattern is partially dissolved and removed before the first negative resist pattern is partially removed.
And irradiating or heat-treating the negative resist pattern.

A twelfth pattern forming method according to the present invention is a method of selectively irradiating light in the eleventh pattern forming method.

In a first method of manufacturing a semiconductor device according to the present invention, after forming a negative resist film on a semiconductor substrate, a resist pattern is formed by any of the first to twelfth pattern forming methods. Is the way.

A first semiconductor device according to the present invention is manufactured by the above-described first semiconductor device manufacturing method.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 In the pattern forming method according to the first embodiment of the present invention, after forming a negative resist on a semiconductor substrate (first negative resist pattern), the formed pattern is partially dissolved by, for example, a stripper. By the removal method, formation of a pattern (second negative resist pattern) having a size equal to or smaller than the exposure wavelength can be realized.

As the negative resist, a resist which can be redissolved by surface treatment with a stripping solution is used. For example, a chemically amplified negative resist is used. As the chemically amplified negative resist, an acid-catalyzed chemically amplified negative resist is particularly preferable. The acid-catalyzed chemically amplified negative resist is composed of, for example, a novolak resin, melamine (crosslinking agent) and an acid generator, and the crosslinked portion is an acidic film in which phenolic hydroxyl groups remain.

When the acid-catalyzed chemically amplified negative resist is used, it is preferable to use a basic stripper as the stripper. As the basic stripping solution, for example, a solution in which a basic compound such as an amino compound, an imino compound, a hydroxide, a pyridine base or a salt thereof is dissolved in a solvent, for example, an aqueous solution, an organic solvent or an organic solvent is used. A mixed solvent with water is exemplified. Further, by adjusting the concentration of the basic compound in the stripping solution, the amount of the resist dissolved and removed can be controlled. Examples of the basic compound include, for example, tetramethylammonium hydroxide, ethanolamine, triethylamine, ammonia, methylamine, ethylamine, propylamine, butylamine, hexylamine, cyclohexylamine, decylamine, cetylamine, hydrazine, tetramethylenediamine, hexamethylene Diamine, benzylamine, aniline, naphthylamine, phenylenediamine, toluenediamine, diaminodiphenylmethane, hexamethyltetramine, piperidine or piperazine, and the like, but are not limited to the above, as long as they are soluble in the solvent of the stripping solution. Anything is fine. Specific examples include a basic aqueous solution containing tetramethylammonium hydroxide, or a basic aqueous solution to which an alcohol is added.

As the stripping solution, an organic solvent or a mixed solvent of water and an organic solvent can be used. Organic solvents include alcohols, ketones, ethers,
Esters, halogenated hydrocarbons, benzenes, alkoxybenzenes, cyclic ketones and the like, for example, toluene, xylene, methoxybenzene, ethoxybenzene,
Phenol, benzene, pyridine, cyclohexane, dioxane, methyl ethyl ketone, methyl isobutyl ketone, acetone, t-butyl acetate, n-butyl acetate, ethyl acetate, tetrahydrofuran, diethyl ether, isopropyl ether, methyl cellosolve, ethyl cellosolve, N-methylpyrrolidone, Dimethyl sulfoxide,
N, N'-dimethylformamide, ethanol, methanol, isopropanol, butyl alcohol, ethylene glycol, ethylbenzene, diethylbenzene, n-
Butyl ether, n-hexane, n-heptane, methoxybenzene, ethoxybenzene, phenetol, veratrol, γ-butyrolactone, chloroform, etc., and the resist pattern alone or in accordance with the solubility of the material used for the resist film. May be mixed in a range that does not completely dissolve the. In particular, a mixed solution of a polar organic solvent, which is a good solvent for dissolving the resist pattern, and water, which is a poor solvent, is preferably used as the stripping solution.

Hereinafter, the present embodiment will be described with reference to the drawings. FIGS. 1A to 1E are explanatory views showing a method of forming a resist pattern according to a first embodiment of the present invention in the order of steps, wherein 2 is a semiconductor substrate, 3 is a step due to wiring or the like, and 4 is, for example, Chemically amplified negative resist film;
a is the opening, 6a is the first negative resist pattern, 7 is the surface soluble layer, and 8 is the second negative resist pattern.

First, a chemically amplified negative resist film 4 for excimer is deposited on the semiconductor substrate 2 on which the step 3 is formed.
It is provided with a film thickness of 0 to 20000% (FIG. 1 (a)). still,
Before applying the negative resist, the surface of the semiconductor substrate 2 may be treated with hexamethylene disilazane or the like to enhance the adhesion to the resist film 4. Also, the resist film 4
An upper layer material may be applied thereon. Further, heat treatment may be performed after the application.

Next, a photomask 5 adjusted to obtain a pattern having a line width of 0.25 μm (corresponding to the width of the opening 5a) (1.25 μm in the case of 5: 1 reduction projection exposure)
The exposure light (KrF light) was selectively irradiated toward the chemically amplified negative resist film 4 for excimer by focusing on the lower part of the step 3 of the semiconductor substrate 2 using the (line width of).

Next, when a developing process is performed, in this embodiment, since the pattern size is larger than the wavelength of the exposure light, the first negative resist pattern 6a of 0.25 μm is formed on both the upper and lower portions of the step 3. Obtained {FIG. 1 (c)}.

Next, when the pattern 6a is washed (stripping treatment) with a basic stripping solution adjusted so that the resist pattern can be partially dissolved, the surface soluble layer 7 of the first negative resist pattern 6a is removed. {Fig. 1 (d)} dissolves,
The line width was reduced by 0.10 μm, and a second negative resist pattern 8 of 0.15 μm was obtained (FIG. 1E).

As the stripping solution, a basic aqueous solution or an organic solvent or a mixed solvent of an organic solvent and water can be used as described above. Preferably, a basic aqueous solution containing tetramethylammonium hydroxide is used. Alternatively, a solution obtained by adding an alcohol to this basic aqueous solution can be used.

Further, before performing the above-mentioned stripping treatment, the semiconductor substrate 2 may be subjected to a heat treatment at 60 to 150 ° C. for about 1 to 3 minutes on a hot plate to control the crosslink density of the resist pattern. Details are described in Embodiment 3 below.

The first negative resist pattern 6a
The mechanism for solubilizing the surface soluble layer 7 in the stripping solution is described as follows. Among the chemically amplified negative resists for excimers, those composed of a novolak resin, melamine (crosslinking agent) and an acid generator are widely used, and are alkali-soluble. When irradiated with light, an acid is generated, a cross-linking reaction occurs between the novolak resin and melamine, the molecular weight increases, and it becomes hardly soluble in an alkali developing solution containing a predetermined concentration of tetramethylammonium hydroxide. That is, the feature of this resist is that the difference in solubility between the irradiated part and the non-irradiated part in the basic stripping solution is large. However, the surface soluble layer of the resist pattern has a low crosslinking density due to the action of inhibiting polymerization of oxygen, and has lower solvent resistance than the inside. In addition, since the phenolic hydroxyl group remains in the molecular structure of the portion crosslinked by light irradiation,
Solubilized depending on the concentration and type of base. Therefore,
When the first negative type resist pattern 6a is subjected to a release treatment with a solvent capable of dissolving only the surface soluble layer or a basic release liquid,
Only the soluble layer on the resist surface is dissolved, and the resist pattern (remaining portion of the resist) can be thinned, whereby a fine pattern having an exposure wavelength or less can be stably formed.

In the above description, the case where a resist pattern is formed on the semiconductor substrate 2 has been described. However, in the manufacture of a semiconductor device, a resist pattern is formed not only on a semiconductor substrate but also on an insulating film such as a silicon oxide film or on various films such as a polysilicon film and a metal film. This embodiment can be applied when forming a negative resist pattern on all of these base films. In this specification, "on a semiconductor substrate" includes all of these cases.

Embodiment 2 FIGS. 2A to 2C are explanatory diagrams showing a pattern forming method according to a second embodiment of the present invention, specifically showing a method of forming a hole pattern with a narrow interval from the top and in the order of steps. , 17 are a first negative resist pattern, and 18 is a second negative resist pattern.

FIG. 3 is a plan view showing a hole pattern formed by a conventional method.
Is a dimple. That is, according to the prior art, when the hole pattern 19 is obtained using an acid-catalyzed chemically amplified negative resist for KrF, a pattern with a narrow hole interval, for example, as shown in the figure, a hole size of 0.30 μm and a hole interval of 0 When a halftone mask is used to form an array pattern of .18 μm (smaller than the exposure wavelength), dimples (dents) 20 occur due to subpeaks, and unnecessary holes are formed after etching.

However, in the present embodiment, as described below, the influence of the sub-peak is small, and no dimple occurs. Hereinafter, this embodiment will be described with reference to FIG.
First, a hole size of 0.24 μm and a hole interval of 0.24 μm were formed on a semiconductor substrate by a usual photolithography using an acid-catalyzed chemically amplified negative resist for KrF laser.
A hole pattern 17, which is a first negative resist pattern having a thickness of μm, is formed (FIG. 2A). As described above, in the case of the hole interval longer than the light source wavelength (in this case, 0.24 μm), the influence of the sub-peak is small, and no dimple occurs.

Next, as in the first embodiment, the surface soluble layer 7 of the first negative resist pattern 17 is removed with a stripper (FIG. 2B). Specifically, stripping is performed using a 3.0 wt% aqueous solution of tetramethylammonium hydroxide as a stripping solution. As a result, a hole pattern 18, which is a second negative resist pattern having a dimple-free hole size of 0.30 μm, in which the dimension of the resist hole pattern recedes by 0.06 μm, was obtained {FIG.
(C)｝. That is, it was possible to form the resist pattern 18 having a narrow hole interval, which could not be obtained by the conventional technique.

Before the above-mentioned stripping treatment, the cross-linking density of the surface soluble layer of the resist pattern can be controlled by exposure or heat treatment to change the dimensions of the finally obtained resist hole pattern. Details are described in Embodiment 3 below.

In the present embodiment, the process of Embodiment 1 is applied to a resist hole pattern, and the generated resist pattern is different. However, since the process and its effect are the same, repeated description will be omitted. This effect is also applicable to a resist hole pattern formed using a halftone mask or a normal mask.

Embodiment 3 The pattern forming method according to the third embodiment of the present invention is characterized in that, after the formation of the first negative resist pattern of the first or second embodiment, before the dissolution and removal with a stripping liquid, Heat treatment,
This is a method for controlling the thickness of the surface soluble layer capable of dissolving and removing the resist pattern by the stripping solution.

Further, at the time of forming the first negative resist pattern and at the time of the light irradiation, g-line, i-line,
rF excimer, ArF excimer, Deep-UV, EB
(Electron beam) or X-ray can be used, and it is preferable to irradiate the photosensitive wavelength of the negative resist.

Further, by performing the light irradiation using a photomask, it is possible to select a portion for controlling the thickness which can be dissolved and removed.

Hereinafter, this embodiment will be described with reference to the drawings. FIGS. 4A to 4D are explanatory views showing a pattern forming method according to the third embodiment of the present invention, specifically, a method of forming a fine resist pattern in the order of steps, and 9 is a second negative. Of the mold resist pattern after light irradiation, 1
0 is a photomask and 10a is an opening thereof.

First, a 0.25 μm-wide L / S first negative resist pattern 6a of an acid-catalyzed chemically amplified negative resist for KrF laser is formed on the semiconductor substrate 2 by ordinary photolithography {FIG. a)｝.

Next, the first 0.25 μm width L / S is used.
Using a photomask 10 having a desired pattern and having an opening 10a only in a portion where the line width is not desired to be reduced with respect to the negative resist pattern 6a, the first negative resist pattern 6a is subjected to a KrF excimer process. ~ 30
A light irradiation of 00 mJ / cm ² is performed {FIG. 4 (b)}. First
In the negative resist pattern 6a, the cross-linking reaction is selectively promoted only in the exposed portions by the exposure treatment, and the cross-linking density is increased, so that the negative resist pattern 6a becomes more insoluble.
(C)｝.

Next, the semiconductor substrate 2 may be heat-treated on a hot plate at 60 to 150 ° C. for about 1 to 3 minutes to further control the crosslink density of the resist pattern.

Next, the first negative resist pattern 6a
The surface soluble layer 7 is peeled and removed with a basic peeling solution. Specifically, 2.38 wt% pure water / isopropanol of tetramethylammonium hydroxide = 90/1
0 (volume ratio) of the solution is stripped as a stripping solution.
(D)｝. Thereafter, a heat treatment is performed at 100 to 130 ° C. for about 1 to 3 minutes to remove moisture and the like in the pattern after peeling. As a result, the dimension of the exposed portion 9 of the second negative resist pattern 8 is reduced by 0.01 μm from the first negative resist pattern 6a, while the remaining portion is reduced by 0.1 μm in other portions, Initially, it could not be formed by photolithography with a KrF excimer laser.
5 μmL of the second negative resist wiring pattern 8 can be selectively formed.

Further, as in the first embodiment, a basic stripping solution, an organic solvent or a mixed solvent of an organic solvent and water can be used for stripping. Preferably, tetramethylammonium hydroxide is used. Or a solution obtained by adding an alcohol to the basic aqueous solution.

Next, the first negative resist pattern 6a
The mechanism for solubilizing the surface soluble layer 7 in the stripping solution is as follows.
Since this is the same as that described in the first embodiment, a duplicate description will be omitted.

That is, in the present embodiment, the amount of light irradiation can control the solubility of the resist pattern and the heat diffusion can control the diffusion length of the base to control the amount of reduction in the size of the resist pattern. At this time, by selectively exposing using a photomask, the solubility can be controlled by the crosslinking control, and the resist pattern can be selectively thinned.

Embodiment 4 FIGS. 5A to 5D are explanatory views showing a pattern forming method according to the fourth embodiment of the present invention, specifically, a method of forming a fine resist pattern from the top surface in the order of steps. Photo mask, 10a
Is an opening, 10b is a shielding portion, 12 is a second negative resist pattern, and 12a is a thinned portion.

First, a first negative resist pattern 6a is formed in the same manner as in the third embodiment {FIG.
(A)｝. Next, for the first negative resist pattern 6a having a width L / S of 0.25 μm, a first photomask 10 including a pattern (band-shaped portion 10b) capable of shielding a portion to be reduced in line width is used. 10-3000 mJ by KrF excimer for negative resist pattern 6a
/ Cm ² light irradiation {FIG. 5 (b)}. In the present embodiment, the strip 10b blocks light, and the upper and lower strips 10a emit light. By this exposure treatment, a cross-linking reaction selectively proceeds only in the exposed portion, and the portion becomes more insoluble.

Next, in the same manner as in the second embodiment, the surface soluble layer 7 of the resist pattern is removed with a stripper to obtain a second negative resist pattern 12. Specifically, peeling is performed with a 3.20 wt% aqueous solution of tetramethylammonium hydroxide. As a result, while the dimension of the exposed portion of the second negative resist pattern 12 is reduced by 0.01 μm, the other portion is reduced by 0.1 μm,
A second negative resist pattern having a portion 12a having a partially reduced line width can be formed. The present embodiment is different from the previous embodiment 3 in the pattern of the photomask to be irradiated with light and the generated resist pattern. However, since the process and the effect are the same, further description is omitted. .

Embodiment 5 A process for manufacturing a semiconductor device using a resist pattern formed by the pattern forming method of the above embodiment will be described. As a first example, FIGS. 6A and 6B are explanatory views showing a method of manufacturing a semiconductor device according to a fifth embodiment of the present invention in the order of steps.
Reference numeral 3 denotes an insulating film, 14 denotes a conductive film, and 14a denotes a wiring pattern. First, an insulating film 13 is formed on the semiconductor substrate 2,
Further, a conductive film 14 such as a polysilicon film or an aluminum film is formed thereon, and a second negative resist pattern 8 is formed on the conductive film 14 by the method of the first embodiment {FIG. )｝. Next, the conductive film 14 is etched through the second negative resist pattern 8 to form a thin wiring pattern 14a having a line width smaller than the exposure wavelength.
(FIG. 6B). For example, a wiring pattern having a line width of 0.15 μm can be formed stably.

As a second example, FIGS. 7A and 7B are explanatory views showing a method of manufacturing a semiconductor device according to the fifth embodiment of the present invention in the order of steps, and 14b is a wiring pattern. First, an insulating film 13 is formed on a semiconductor substrate 2, and a conductive film 1 such as a polysilicon film or an aluminum film is further formed thereon.
4 is formed, and a second negative resist pattern is formed on the conductive film 14 by the method of the third embodiment {FIG. 7A}. Next, by etching the conductive film 14 through the second negative resist pattern, for example,
It is possible to form a wiring pattern 14a having a small line width such as a line width of 0.15 μm, and an approximately normal line width 14b having a line width of 0.24 μm, for example.

FIGS. 8A to 8C show a third example.
FIGS. 15A to 15C are explanatory views showing a method of manufacturing a semiconductor device according to a fifth embodiment of the present invention in the order of steps, wherein reference numeral 15 denotes an interlayer insulating film, 16a denotes a conductor plug, and 16b denotes a wiring. First, an insulating film 13 is formed on the semiconductor substrate 2, a conductive film 14 such as a polysilicon film or an aluminum film is further formed thereon, and a resist is formed on the conductive film 14 by the method of the fourth embodiment. Forming pattern 12 {FIG. 8A}. By etching the conductive film 14 through the resist pattern 12,
A wiring pattern 14a having a partially narrow line width is formed (FIG. 8B). Thereafter, an interlayer insulating film 15 is further formed,
A vertically extending conductive wire plug 16a is formed between the two thinned wiring patterns 14a in the interlayer insulating film 15 and connected to the wiring 16b formed on the interlayer insulating film 15 {FIG. ｝. When this example is applied to a semiconductor memory, the wiring pattern 14a becomes a word line and the wiring 16b becomes a bit line.

After the steps described above, the semiconductor manufacturing process is further continued. However, since this is a conventionally known method, the description thereof will be omitted. By the above method,
A semiconductor device having a fine pattern with a line width exceeding the limit of the exposure wavelength can be manufactured.

[0060]

[Embodiment 1] Using a chemically amplified negative resist on a semiconductor substrate, a resist wiring pattern of 0.35 μmL / S is formed by the pattern forming method described in the first embodiment. That is, first, a resist was dropped on a Si wafer and spin-coated, and then prebaked at 80 ° C./70 seconds to evaporate the solvent in the resist to form a resist with a film thickness of about 0.8 μm. Next, as an exposure apparatus, KrF
0.35μmL / S using excimer reduction projection exposure equipment
The resist was exposed using an exposure photomask having a pattern. Next, PEB (post-exposure bake) treatment was performed at 115 ° C./90 seconds, followed by development using an alkaline developer (trade name: NMD3, manufactured by Tokyo Ohka Kogyo Co., Ltd.), and 0.35 μmL / An S resist wiring pattern (first negative resist pattern) was obtained. Next, the resist pattern was immersed in a stripper having the composition shown in Table 1 at room temperature for 60 seconds to remove the surface soluble layer of the resist pattern, washed with pure water, and post-baked at 110 ° C. for 60 seconds. Was. Thus, a wiring pattern (second negative resist pattern) having the dimensions shown in Table 1 was obtained.

[0061]

[Table 1]

When pure water is used as the stripping solution, the wiring dimensions do not change at all, but the reduction in dimensions increases as the amount of organic solvent or base added increases. If the amount is excessive, the wiring pattern is completely dissolved.

Embodiment 2 FIG. A partially thinned pattern was formed by using the pattern forming method of the third embodiment.
That is, first, an acid-catalyzed chemically amplified negative resist for a KrF laser is used on a semiconductor substrate by ordinary photolithography to form a resist wiring pattern (first negative) having a thickness of about 0.7 μm and a width of 0.25 μm L / S. Type resist pattern)
Was formed. Next, an exposure process of 50 to 3000 mJ / cm ² is performed on the resist wiring pattern having a width of L / S of 0.250 μm by KrF excimer using a photomask having an opening only in the wiring whose line width is not desired to be reduced. Was.
Further, the resist pattern was immersed in a stripping solution of an aqueous solution containing 2.5 wt% of tetramethylammonium hydroxide and 5 wt% of isopropanol for 60 seconds to remove the surface soluble layer of the resist pattern, and then washed with pure water.
Post-baking was performed at a temperature of 60 ° C./second (second negative resist pattern). Table 2 shows the wiring dimensions of the exposed part and the unexposed part and their reduction amounts.

[0064]

[Table 2]

As the exposure amount increases, the reduction amount of the wiring in the exposed portion decreases. This is because the crosslink density of the resist film due to the exposure treatment is increased, and the solvent resistance is improved.

Embodiment 3 FIG. An aluminum film is formed by a sputtering apparatus on a semiconductor substrate on which an oxide film of 2000 mm is formed as an insulating film. On this aluminum film, a pattern with a partially reduced line width was formed by the pattern forming method of the fourth embodiment. First, a resist wiring pattern (first negative resist pattern) having a film thickness of about 0.7 μm and a width of 0.25 μm L / S using an acid-catalyzed chemically amplified negative resist for KrF laser by ordinary photolithography. Formed. Next, for a resist wiring pattern having a width of 0.250 μm L / S, a Kr is formed using a photomask having an opening only in a portion of the wiring where the line width is not desired to be reduced.
After performing an exposure treatment of 0 to 1000 mJ / cm ² by F excimer, a heat treatment was performed at 100 ° C. to 180 ° C. for 60 seconds. Further, 1.0 wt% of isopropylamine and N
As a stripper of an aqueous solution containing 3 wt% of methylpyrrolidone, the resist pattern was immersed for 60 seconds to remove the surface soluble layer of the resist pattern, washed with pure water, and post-baked at 110 ° C. for 60 seconds. As a result, a result as shown in Table 3 was obtained, and a wiring pattern having a partially different line width was obtained (second negative resist pattern). As the exposure amount increases and the heat treatment temperature increases, the crosslink density of the resist film increases, and the reduction amount of the line width after peeling decreases.

[0067]

[Table 3]

Also, an exposure amount of 1000 mJ / cm ² and 1
In the heat treatment at 20 ° C., the line width of the exposed portion is 0.220 μm,
A wiring pattern in which the line width of the unexposed portion was 0.130 μm and the line width was partially different was obtained. Further, as shown in FIG. 8, the aluminum film was etched through the formed resist pattern to partially form an aluminum wiring having a narrow line width. Further, a vertically extending conductor plug was formed between the interlayer insulating film and the two wiring patterns having a reduced line width, and was connected to the aluminum wiring on the interlayer insulating film. This process was applied to a semiconductor memory.

[0069]

According to the first pattern forming method of the present invention, a negative resist film is exposed and developed to form a first negative resist pattern, and the first negative resist pattern is partially removed. The pattern method of forming the second negative resist pattern has an effect that a fine resist pattern exceeding the limit of the exposure wavelength can be formed stably.

The second pattern forming method of the present invention is the same as the first pattern forming method, wherein the surface of the first negative resist pattern is dissolved and removed with a stripping solution to form a second negative resist pattern. With this method, a fine resist pattern exceeding the limit of the exposure wavelength can be formed stably.

The third pattern forming method according to the present invention is the method according to the first or second pattern forming method, wherein the negative resist is a fine resist pattern exceeding the limit of the exposure wavelength by a chemically amplified negative resist. Can be formed stably.

The fourth pattern forming method of the present invention is the third pattern forming method, wherein the chemically amplified negative resist is an acidic film formed by the remaining phenolic hydroxyl group, and is a fine pattern exceeding the limit of the exposure wavelength. There is an effect that a resist pattern can be formed stably.

A fifth pattern forming method according to the present invention is the method according to any of the second to fourth pattern forming methods, wherein the stripping solution is a basic stripping solution, and the fine resist pattern exceeds the exposure wavelength limit. Can be formed stably.

A sixth pattern forming method according to the present invention is the method according to the fifth pattern forming method, wherein the basic stripping solution is an amino compound, an imino compound, a hydroxide, a pyridine base or a salt thereof. An aqueous solution of the compound,
The method of adding an organic solvent or a mixed solvent of an organic solvent and water can stably form a fine resist pattern exceeding the limit of the exposure wavelength.

A seventh pattern forming method according to the present invention is the method according to the sixth pattern forming method, wherein the basic stripping solution is a basic aqueous solution containing tetramethylammonium hydroxide or an alcohol added to the basic aqueous solution. Thus, there is an effect that a fine resist pattern exceeding the limit of the exposure wavelength can be formed stably.

The eighth pattern forming method according to the present invention is the method according to the sixth or seventh pattern forming method, wherein the concentration of the basic compound is adjusted to control the amount of dissolved and removed, and the formation of a finer pattern is selected. This has the effect of being able to be performed in a targeted manner.

A ninth pattern forming method according to the present invention is the method according to any one of the second to fourth pattern forming methods, wherein the stripping solution is an organic solvent or a mixed solvent of water and an organic solvent. There is an effect that a pattern can be selectively formed.

A tenth pattern forming method according to the present invention is the method according to the sixth or ninth pattern forming method, wherein the dissolution removal amount is controlled by adjusting the mixing ratio of water and an organic solvent. Has the effect that the formation of sapphire can be performed selectively.

According to an eleventh pattern forming method of the present invention, in the first pattern forming method, the first negative resist pattern is irradiated with light before partially dissolving and removing the first negative resist pattern. Or by heat treatment,
Further, there is an effect that a fine pattern can be selectively formed.

According to the twelfth pattern forming method of the present invention, the fine pattern can be selectively formed by selectively irradiating light in the eleventh pattern forming method.

The first method of manufacturing a semiconductor device according to the present invention
After a negative resist film is formed on a semiconductor substrate, a resist pattern is formed by any one of the first to twelfth pattern forming methods. Excessive fine patterns can be formed stably.

The first semiconductor device of the present invention is manufactured by the above-described first semiconductor device manufacturing method, and can form a semiconductor device having a fine pattern.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a method of forming a resist pattern according to a first embodiment of the present invention in the order of steps.

FIG. 2 is an explanatory view showing a pattern forming method according to a second embodiment of the present invention from the top and in the order of steps.

FIG. 3 is a plan view showing a hole pattern formed by a conventional method.

FIG. 4 is an explanatory view showing a pattern forming method according to a third embodiment of the present invention in the order of steps.

FIG. 5 is an explanatory view showing a pattern forming method according to a fourth embodiment of the present invention from the top and in the order of steps.

FIG. 6 is an explanatory view showing a method of manufacturing a semiconductor device according to a fifth embodiment of the present invention in the order of steps.

FIG. 7 is an explanatory diagram showing a method of manufacturing a semiconductor device according to a fifth embodiment of the present invention in the order of steps.

FIG. 8 is an explanatory view showing a method of manufacturing a semiconductor device according to a fifth embodiment of the present invention in the order of steps.

FIG. 9 is an explanatory view showing a conventional method of forming a resist pattern by photolithography in the order of steps.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 semiconductor substrate, 3 steps, 4 chemically amplified negative resist film, 5, 10 photomask, 6 a first negative resist pattern, 7 surface soluble layer, 8 second negative resist pattern, 10 photomask, 12 A second negative resist pattern, 13 insulating films, 14 conductive films,
15 interlayer insulating film, 16a conductive wire plug, 16b wiring, 17 first negative resist pattern, 18 second
Negative resist pattern.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takeo Ishibashi 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation F-term (reference) 2H025 AA02 AB15 AB16 AC05 AC08 AD01 BE00 BE10 BG00 CB41 CC17 CC20 FA12 FA28 FA33 FA48 2H096 AA25 AA26 BA06 EA05 EA07 HA01 HA03 HA30 LA03 5F046 LA18 LA19 MA06

Claims (14)

[Claims] A first resist film exposed to light and developed to form a first resist film;
Forming a negative resist pattern and partially removing the first negative resist pattern to form a second negative resist pattern. 2. The pattern forming method according to claim 1, wherein the second negative resist pattern is formed by dissolving and removing a surface portion of the first negative resist pattern with a stripping solution. 3. The pattern forming method according to claim 1, wherein the negative resist is a chemically amplified negative resist. 4. The pattern forming method according to claim 3, wherein the chemically amplified negative resist is an acidic film formed by remaining phenolic hydroxyl groups. 5. The pattern forming method according to claim 2, wherein the stripping solution is a basic stripping solution. 6. A basic stripping solution comprising an amino compound, an imino compound, a hydroxide, a pyridine base or a basic compound such as a salt thereof, added to an aqueous solution, an organic solvent, or a mixed solvent of an organic solvent and water. The pattern forming method according to claim 5, wherein the pattern is formed. 7. The pattern forming method according to claim 6, wherein the basic stripping solution is a basic aqueous solution containing tetramethylammonium hydroxide or a solution obtained by adding an alcohol to the basic aqueous solution. 8. The pattern forming method according to claim 6, wherein the amount of dissolution removal is controlled by adjusting the concentration of the basic compound. 9. The pattern forming method according to claim 2, wherein the stripping solution is an organic solvent or a mixed solvent of water and an organic solvent. 10. The pattern forming method according to claim 6, wherein a dissolution removal amount is controlled by adjusting a mixing ratio of water and an organic solvent. 11. The pattern forming method according to claim 1, wherein the first negative resist pattern is subjected to light irradiation or heat treatment before partially dissolving and removing the first negative resist pattern. 12. The pattern forming method according to claim 11, wherein light is selectively irradiated. 13. A method of manufacturing a semiconductor device, comprising: forming a negative resist film on a semiconductor substrate; and forming a resist pattern by the pattern forming method according to claim 1. 14. A semiconductor device manufactured by the method for manufacturing a semiconductor device according to claim 13.