JPH04149441A - Formation of pattern - Google Patents

Abstract

PURPOSE:To obtain high resolution by coating a substrate with a photosensitive composition containing hydroxyl group containing resin, a photosensitive acid generating agent, and a hydroxyl group generating compound and forming a resin film, and irradiating the film with far ultraviolet light selectively and discriminating between an irradiated area and an unirradiated area. CONSTITUTION:The substrate 2 is coated with the photosensitive composition containing the hydroxyl group containing resin, photosensitive acid generating agent, and hydroxyl group generating compound to form the resin film 1, which is irradiated selectively with the far ultraviolet light 4 by using a desired mask 5, thereby discriminating between the irradiated area 1a and unirradiated area 1b of the resin film 1. Then the resin film 1 is heated, the irradiated area 1a is processed with an organic metal reagent 7, and the unirradiated area 1b is processed with oxygen plasma for selective removal. The hydroxyl group generating compound consists essentially of a complete or partial ester compound of an organic acid compound shown by a formula I and an alkali soluble compound with a phenol hydroxyl group. IN the formula I, R<1> - R<3> are hydrogen, an alkyl group, or an alkyl group. Consequently, high resolving power is obtained and pattern profile is made excellent.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pattern forming method, and more particularly, it relates to a pattern forming method with high resolution and high sensitivity that can be used to manufacture semiconductor integrated circuits. The present invention relates to a pattern forming method capable of obtaining a good pattern shape.

[Prior art and problems to be solved by the invention] Currently, LM, 4M dynamic random access memory (D
Large-capacity integrated circuits (LSIs), such as RAM), are manufactured using a positive photoresist made of novolac resin and naphthoquinone diazide, and G-line light from a mercury lamp (wavelength: 436n,
m) is selectively irradiated and then patterned. The minimum pattern size is 1 μm to 0.8 μm. It is czm. However, 16M
As the degree of integration of LSIs increases in the future, as seen in DRAMs, a half-micron pattern forming method will become necessary. Therefore, a pattern forming method using a KrF excimer laser, which is a shorter wavelength light source, is currently being researched as a light source.

Resists used for deep ultraviolet light, such as KrF excimer laser, include novolac resin-naphthoquinone diazide positive photoresists such as PR1024 (product of Magdermid), and polymethyl methacrylate (PM).
MA), polyglycidyl methacrylate (PGMA)
, polychloromethylated styrene (CMS), etc. have been proposed.

PMMA and PGMA have low sensitivity and poor dry etching resistance. CMS has good dry etching resistance but low sensitivity. PR1024 has good dry etching resistance and its sensitivity is higher than the above resists, but its sensitivity is lower than when exposed to g-line.

Next, a conventional pattern forming method will be explained.

FIGS. 2A to 2C are cross-sectional views of a conventional pattern forming method using a novolak-naphthoquinonediazide-based positive resist (for example, PR1024).

Referring to FIG. 2A, PR1024 is placed on the substrate 2 to be processed.
is coated and prebaked to obtain a resist film 1 with a thickness of 1.0 μm.

Next, referring to FIG. 2B, resist film 1 is selectively irradiated with KrF excimer laser light 4 using a mask.

As a result, the resist film 1 is divided into an irradiated area 1a and a non-irradiated area 1.
It is classified into b.

Thereafter, referring to FIG. 2C, development is performed using a 2.38% by weight aqueous tetramethylammonium hydroxide solution to obtain a resist pattern 9 from which the irradiated area 1a has been removed.

The conventional resist pattern forming method configured as described above has the following problems.

That is, since a novolac-naphthoquinone diazide positive resist such as PR1024 has a large absorption of far ultraviolet light, referring to FIG. 2B, the absorption of light is large on the surface of the resist film 1, and the lower layer of the resist film Light does not reach the area. As a result, after development, as shown in FIG. 2C, the cross-sectional shape of the resist pattern 9 becomes triangular in shape, tapering upward, which poses a problem in that a fine pattern cannot be obtained with high accuracy.

Furthermore, conventional pattern forming methods that use light with a wavelength of 300 to 500 nm instead of deep ultraviolet light have the following problems.

Referring to FIG. 3, when there is a step 2a on the substrate 2 to be processed, there is a problem in that the light 20 is scattered by the step 2a, making it impossible to obtain a good pattern shape. Such a phenomenon is called a notching phenomenon. Similarly, when a film such as A1 that easily reflects light is formed on the substrate 2 to be processed, there is a problem that a good pattern shape cannot be obtained due to the influence of the reflected light. .

4A to 4D show another conventional example of the resist pattern forming method described in Japanese Patent Application Laid-Open No. 63-253356.

Referring to FIG. 4A, on the substrate 2 to be processed, novolac-
A naphthoquinone diazide resist film 1 is formed. Next, using the mask 5, the resist film 1 is selectively irradiated with light having a wavelength of 300 to 500 nm emitted from a high-pressure mercury lamp. This light irradiation causes a crosslinking reaction of the resin in the irradiated area 1a.

Next, referring to FIG. 4B, the entire surface of resist film 1 is irradiated with light of the same wavelength to completely decompose the photosensitive agent.

Thereafter, with reference to FIG. 4C, on the entire surface of the substrate 2 to be processed,
Apply trimethylsilyldimethylamine vapor. As a result, the portion excluding the irradiated area 1a, that is, the upper layer of the non-irradiated area 1b, is selectively silylated, and the silylated layer 1
Changes to 4.

Referring to FIG. 4D, upon development by reactive ion etching (RIE) using 02 gas, the silylated layer 14 remains as a 5102 layer 15, while the irradiated area 1a is removed and the resist Pattern 9 is processed substrate 2
formed on top.

However, in other conventional examples constructed as described above, since light with a wavelength of 300 to 500 nm is used, the crosslinking reaction of the resin is not sufficiently carried out. As a result, with reference to FIG. 4C, the selectivity of the silylation reaction (silylation reaction in the upper part of the irradiated area 1a and
silylation reaction in the upper layer) becomes lower,
Furthermore, referring to FIG. 4D, there was a problem in that the distinction between exposed areas and unexposed areas became unclear, making it impossible to obtain fine patterns with high accuracy. Furthermore, this conventional method also has the problem of the notching effect described with reference to FIG.

B. Roland et al., 5PIE, Vol. 920, p.
120-p, 127 (1988) discloses a patterning method for silylating the surface of irradiated areas.

In this pattern forming method, a resist based on novolak-naphthoquinonediazide is used.

This resist is designed for mercury lamp g-line light (436 nm) or i-line light (365 nm), so
It is not a resist that can exhibit sufficient performance in deep ultraviolet light of 00 nm or less. Furthermore, since the concentration of hydroxyl groups in the exposed areas is not sufficient, silylation cannot be carried out sufficiently in the exposed areas. For this reason, the difference in silylation between the exposed and unexposed areas is small, and it is only possible to increase the selectivity during etching. For this reason, high resolution could not be obtained and dimensional controllability was poor.

An object of the present invention is to provide a pattern forming method that can perform exposure using deep ultraviolet light, can achieve high resolution of half a micron or less, and has a good pattern profile.

[Means for Solving the Problems] A pattern forming method according to the present invention uses a photosensitive composition containing a hydroxyl group-containing resin, a photosensitive acid generator, and a hydroxyl group-generating compound that generates hydroxyl groups under acidic conditions as a substrate. Using the process of coating and forming a resin film on top and the desired mask,
A step of selectively irradiating the resin film with deep ultraviolet light with a wavelength of 150 to 300 nm, thereby distinguishing the resin film into irradiated areas and non-irradiated areas, a step of heat-treating the resin film, and irradiation of the resin film. treating the resin film with an organometallic reagent to react and bind the organometallic reagent to the regions; and treating the resin film with an oxygen plasma to selectively remove non-irradiated areas of the resin film. .

According to this invention, the hydroxyl group-forming compound is a complete or partial ester compound of at least one organic acid compound represented by the following general formulas [1-4] and an alkali-soluble compound having a phenolic hydroxyl group, RI O -C-0-C-OH [1 C-C-OH [2 Colo R70 R8-C-0-S-OH [3 I R90 RlI Q Rl + (-S -OH[4] (here R1-R12 have hydrogen, an alkyl group, or an aryl group, and may be the same or different.) and/or R1-R12 have hydrogen, an alkyl group, or an aryl group, and may be the same or different. The main component is a completely or partially ether compound with an alkali-soluble compound having a hydroxyl group.

RI (-C OH "5 (R mouth represents an alkyl group, and R eyes to R mouth represent an alkyl group or an aryl group, which may be the same or different.) R1 to Rl l preferably have 3 carbon atoms The following alkyl groups are preferred, and a methyl group is more preferred.

According to one preferred embodiment of this invention, the alkali-soluble compound of the hydroxyl group-forming compound is the following (i) to (
iii) at least one selected from the group consisting of
It is a seed.

(i) A polyvinylphenol derivative represented by the following general formula [6 CH2-CH]r (where n is an integer of 2 to 20, and R16 to R20 are hydrogen, an alkyl group, an aryl group, or a hydroxyl group) (Procedure 1) At least one phenol derivative represented by the following general formula [7] and the following Novolac resin (length: 1,000 margins) which is a polycondensate with at least one ketone derivative or aldehyde derivative represented by the general formula [8] (Here, R21 to R25 are hydrogen, an alkyl group, or an aryl group. and may be the same or different.

) (iii) Poly(
N-(p-hydroxyphenyl)maleimide derivative h These alkali-soluble compounds may be used alone or in combination of one or more types.

According to this invention, a photosensitive composition containing a hydroxyl group-containing resin, a photosensitive acid generator, and a hydroxyl group-generating compound is applied onto a substrate, and after exposure and heat treatment (post-exposure bake; hereinafter abbreviated as FEB). , a pattern with a good pattern profile can be formed by treatment with an organometallic reagent and then with oxygen plasma.

In the process of treating a resin film with an organometallic reagent according to the present invention, the organometallic reagent may be a liquid or a gas. In addition, as a pretreatment before treatment with an organometallic reagent, in order to increase the affinity between the resin film and the organometallic reagent,
It is preferable to moisten the surface of the resin film with the liquid of the organometallic reagent. Furthermore, instead of moistening the surface of the resin film with the organometallic reagent, the surface of the resin film may be exposed to the vapor of the organometallic reagent.

The hydroxyl group-containing resin used in this invention has a film thickness of 1
It is preferable to have a region in which the transmittance at any exposure wavelength of 150 to 300 nm is 20% or more in μm. Examples of such resins include novolak resin, poly(N(p-hydroxyphenyl)maleimide), polyvinylphenol, and the like. Particularly preferred is polyvinylphenol. These hydroxyl group-containing resins can be used alone, as a mixture, or as a copolymer.

The photosensitive acid generator used in this invention is 150
The acid generator is preferably an acid generator that generates acid with light in the range of ~300 nm. Examples of such acid generators include:
For example, onium salts and sulfonic acid esters as disclosed by J. V. Cr1vello in Polymeric Materials Science and Engineering Vol. 61, p. Photosensitive organic halogen compounds such as those disclosed in Japanese Patent Application Publication No. 2003-110006 can be used.

Examples of organometallic reagents used in this invention include:
Silicon compounds such as hexamethyldisilazane, trimethylsilyldimethylamine, tetrachlorosilane, trimethylchlorosilane, trimethylchlorogermanium,
Germanium compounds such as tetramethoxygermanium, tri(trimethylgermyl)amine, di(triethoxygermyl)amine, trimethylethoxygermanium, diethyltrimethylgermylamine, or tin,
Metal compounds such as titanium, molybdenum, vanadium, chromium, and selenium may be mentioned. Among these,
Particularly preferred are germanium compounds. When germanium compounds are used, G generated after oxygen plasma treatment
The eO2 film can be easily peeled off using a strong acid such as concentrated nitric acid.

In this invention, a hydroxyl group-containing resin, a photosensitive acid generator,
and the ratio of the hydroxyl group-forming compound is 10% of the hydroxyl group-containing resin.
Preferably 0.05 parts by weight of photosensitive acid generator
~20 parts by weight, more preferably 0. The amount is 1 to 10 parts by weight, preferably 1 to 50 parts by weight, and more preferably 5 to 30 parts by weight.

Further, the photosensitive composition used in the present invention is used after being dissolved in a solvent, but there is no particular restriction on the solvent as long as it has sufficient solubility for its components and provides good coating properties. Examples of such solvents include cellosolve solvents such as methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, and ethyl cellosolve acetate, ester solvents such as butyl acetate, amyl acetate, methyl lactate, and ethyl lactate, and methyl isobutyl ketone. Examples include ketone solvents such as , cyclopentanone, and cyclohexanone, highly polar solvents such as dimethylformamide and N-methylpyrrolidone, mixed solvents thereof, and mixed solvents to which aromatic hydrogen is added. The proportion of the solvent used is preferably in the range of 1 to 20 times the total amount of solids by weight.

The pattern forming method according to this invention includes coating, exposure, FE
B, organometallic reagent treatment, and oxygen plasma treatment.

In this invention, the light used for exposure includes far ultraviolet light, such as 254 nm light using a low pressure mercury lamp as a light source, 308 nm, 248 nm light using an excimer laser, etc. as a light source,
222nm, 193nm.

and 157 nm light is preferably used. The light during exposure may be broad rather than monochromatic.

In this invention, the conditions for FEB are preferably 80° C. to 150° C. and about 1 minute to 10 minutes using a hot plate. A convection oven may be used instead of a hot plate. However, in this case, a longer time is usually required than when using a hot plate.

[Operations and Effects of the Invention] In this invention, a photosensitive composition containing a hydroxyl group-containing resin, a photosensitive acid generator, and a hydroxyl group-forming compound is applied onto a substrate to form a resin film, and this resin film is irradiated with deep ultraviolet light. Selective irradiation is used to distinguish irradiated areas from non-irradiated areas. According to this invention, in the irradiated area, acid is generated by the action of the photosensitive acid generator, and hydroxyl groups are generated by the hydroxyl group-generating compound. Therefore, a large amount of hydroxyl groups are present in the irradiated area and react with and bond with the organometallic reagent. In the non-irradiated area, there is no generation of hydroxyl groups from the hydroxyl group-forming compound, and the reaction with the organometallic reagent is suppressed. This causes a large difference in reactivity with the organometallic reagent between the irradiated area and the non-irradiated area. Therefore, according to the present invention, high resolution can be obtained.

Therefore, according to this invention, 150 nm to 300 nm
It is possible to perform exposure using light in the far ultraviolet region of m, and also to achieve a high resolution of half a micron or less, and to obtain a resist pattern with a good pattern profile.

[Examples Examples 1 to 7] Polyvinylphenol (manufactured by Maruzen Petrochemical Co., Ltd.; Mn = 2700. Mw = 5100) shown in the following formula (I) was used as a hydroxyl group-containing resin, (hereinafter referred to as gold) 1+CH2 -CH ÷- The photosensitive acid generator of the following formula and the hydroxyl group-forming compounds (IV) and (IX) shown in Table 1 were dissolved in ethyl lactate in the combinations and amounts shown in Table 2 to prepare a resist solution.

(unwhite under varnish) (IV) (V) (VI) (■) (■) Table 1 of the parent branch number average molecular weight 600 (n=5) 600 (n=5) 600 (n=5) 960 (n=8) 960 (n=8) Esterification rate 60% 80% 100% 60% 80% The esterification rate in Table 1 is expressed by the following formula.

Esterification rate = (number of R1) / (number of tens of hydrogen atoms in R+) (CH2-CH) R (R represents hydrogen or R7.) CH3 CH3-C-0-C- CH3 1st A 1 to 1E are cross-sectional views showing the steps up to forming a pattern using the resist solution prepared as described above.

Referring to FIG. 1A, each of the prepared resist solutions was spin-coded onto a silicon wafer 2, and prebaked at 80°C for 60 seconds on a hot plate to a film thickness of 1 μm.
A resist film 1 of m was obtained.

Next, referring to FIG. 1B, using a desired mask 5 on the resist film 1, the lens aperture N is selectively adjusted.

A, =0. 37. A KrF excimer laser stepper (manufactured by Kon Co., Ltd.) with a laser wavelength of 248 nm was used to irradiate and expose the sample with a KrF excimer laser 4.

Referring to FIG. 1C, the part irradiated with the laser beam becomes the irradiated area 1a, the part where the laser beam was blocked by the mask and was not irradiated becomes the non-irradiated area 1b, and the resist film 1 The area was divided into 1a and non-irradiation area 1b.

Next, this resist film 1 and silicon wafer 2 were subjected to PEB at 110° C. for 90 seconds on a hot plate. The silicon wafer 2 after the FEB treatment was placed in a vacuum oven and heated at a temperature of 110° C. and a pressure of 200 Torr for 20 minutes using tri(trimethylgermyl)amine gas as the organic germanium gas 7, referring to the first DIm. , gelmylation reaction was performed.

As shown in FIG. 1D, in the non-irradiated area 1b, the hydroxyl groups in polyvinylphenol are masked by the hydroxyl group-forming compound, so the reaction with the organic germanium gas 7 is suppressed, and the germylation reaction hardly occurs. do not have. On the other hand, in the irradiated area 1a, there is a large amount of hydroxyl groups generated from the hydroxyl group-generating compound due to the acid generated from the photosensitive acid generator, so that a reaction with the organic germanium gas 7 occurs. Furthermore, since the masking of the hydroxyl group-containing resin by the hydroxyl group-forming compound has disappeared, the organic germanium gas reacts with the hydroxyl group-containing resin. Therefore, a gelmylation reaction occurs in the irradiated area 1a, and a gelmylated layer 8 is formed in the upper layer of the irradiated area 1a. Two molecules of hydroxyl groups can be generated from one molecule of the hydroxyl group-generating compound shown in Table 1. Therefore, there are far more hydroxyl groups in the irradiated area 1a than in the non-irradiated area 1b, resulting in a large difference in the selectivity of the gelmylation reaction.

Next, referring to FIG. 1E, 02 gas 12 is supplied to perform dry development by reactive ion etching. At this time, the germylated layer 8 is oxidized and transformed into a GeO2 film 13. This Ge09 film 13 serves as a shielding agent that is effective against oxygen gas plasma. Therefore, only the non-gelmylated portion, that is, the non-irradiated area 1b, is selectively etched and removed. Due to these selective etchings, the irradiated area 1a and the non-irradiated area 1b are clearly distinguished, and as a result, a good resist pattern 9 with high resolution is obtained.

Furthermore, the film formed in the upper layer of the irradiated area 1a is made of Ga.
Since it is an O2 film, this resist pattern can be easily peeled off with a strong acid such as concentrated nitric acid.

Table 2 shows the sensitivity and resolution during pattern formation in Examples 1 to 7, as well as the cross-sectional shape of the 0.3 μm line and space pattern. In Table 2, the sensitivity is the exposure energy at which the remaining film in the exposed area becomes O, and the resolution is the minimum pattern size that can be resolved with a line and space pattern.

Example 8 In this example, an ester compound (IX) of a meta-cresol novolac resin having a number average molecular weight (Mn) of 600 and R1 was used as a hydroxyl group-forming compound. The esterification rate of this ester compound (IX) was 80%. Using this ester compound (IX) as a hydroxyl group-forming compound, patterns were formed in the same manner as in the above examples using the combinations and blending amounts shown in Table 2, and evaluated in the same manner as in the above examples. The results are shown in Table 2.

Example 9 In this example, a novolac resin was used as the hydroxyl group-containing resin. The composition of the novolak resin is such that the composition ratio of meta-cresol and para-cresol units is 6=4, the number average molecular weight Mn is 1200, and the weight average molecular weight Mw is 7000.
I used the one from

A pattern was formed in the same manner as in the above example, and the pattern forming ability was evaluated. The results are shown in Table 2.

(The following is a blank space) As is clear from Table 2, in the embodiment according to the present invention,
In all cases, high resolution of half a micron or less was achieved, and resist patterns with good pattern profiles were formed.

[Brief explanation of drawings]

FIGS. 1A to 1E are cross-sectional views for explaining the steps of an embodiment according to the present invention. FIGS. 2A to 2C are cross-sectional views showing a conventional pattern forming method using a novolak-naphthoquinonediazide-based positive resist. FIG. 3 is a cross-sectional view showing the notching effect observed in the conventional method. FIGS. 4A to 4D are cross-sectional views showing other conventional methods of forming resist patterns. In the figure, 1 is a resist film, 2 is a substrate to be processed, and 4 is a K
rF excimer laser, 5 is a mask, 7 is organic germanium gas, 8 is a germylated layer, 12 is oxygen gas, 13 is G
In the eO2 film, 1a shows the irradiated area and 1b shows the non-irradiated area. In each figure, the same reference numerals indicate the same or corresponding parts. Figure 1A Figure 1C Figure 3 Figure 4M 4DG

Claims (1)

[Claims] (1) Applying a photosensitive composition containing a hydroxyl group-containing resin, a photosensitive acid generator, and a hydroxyl group-generating compound that generates hydroxyl groups under acidic conditions onto a substrate to form a resin film, as desired. Using a mask of
selectively irradiating the resin film with 00 nm deep ultraviolet light to thereby distinguish the resin film into irradiated areas and non-irradiated areas; heating the resin film; and applying an organic metal to the irradiated area of the resin film. treating the resin film with an organometallic reagent to react and bind the reagents; and treating the resin film with an oxygen plasma to selectively remove non-irradiated areas of the resin film; The hydroxyl group-forming compound is a complete or partial ester compound of at least one organic acid compound represented by the following general formulas [1] to [4] and an alkali-soluble compound having a phenolic hydroxyl group, ▲Mathematical formula, chemical formula, table, etc. ▼ [1] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [2] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [3] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [4] (Here, R ^1 to R^1^2 represent hydrogen, an alkyl group, or an aryl group, and may be the same or different.) and/or at least one alcohol represented by the following general formula [5] and phenol. A method for forming a pattern, the main component being a completely or partially ether compound with an alkali-soluble compound having a hydroxyl group. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [5] (Here, R^1^3 represents an alkyl group, R^1^4 and R^1^5 represent an alkyl group or an aryl group,
They may be the same or different. )