JPS6356655A - Pattern forming method - Google Patents

Abstract

PURPOSE:To prevent a charge-up phenomenon during exposure and to improve the etching resistance of a pattern by irradiating a negative resist made of an arom. vinyl compd. polymer with far ultraviolet rays, charged corpuscular beams or X-rays to form a lower layer. CONSTITUTION:A negative resist made of an arom. vinyl compd. polymer such as chloromethylated polystyrene is applied to a substrate and uniformly irradiated with far ultraviolet rays, charged corpuscular beams or X-rays to form a lower layer. One or two upper layers are then laminated on the lower layer and exposed with charged corpuscular beams to form a pattern. When the upper layer is single, it is preferably formed with a polymer contg. Si. Since the lower layer has superior etching resistance, the thickness can be reduced and a pattern shift due to a charge-up phenomenon during the exposure of the upper layer is prevented.

Description

[Detailed Description of the Invention] [Summary] A negative resist made of an aromatic vinyl compound polymer is applied to a substrate and exposed to deep ultraviolet rays, X-rays, charged particle beams, etc. to create the lower layer film of a multilayer resist process. A pattern forming method used as

[Industrial application field]

The present invention relates to a pattern forming method, and more specifically, to a method of forming resist patterns, which have become increasingly finer in recent years, by a multilayer process.

[Conventional technology]

Conventionally, as a method for forming resist patterns, it has been common to use a single layer of resist and use the resulting pattern as a mask for etching or the like. However, as design rules for semiconductor integrated circuits become finer and etching materials become more difficult to etch,
Pattern formation using a single layer resist has reached its limit.

As a countermeasure to this problem, pattern formation using multilayer resist processes such as pie level and tri level is being advanced and put into practical use. The basic idea of pattern formation using this multilayer resist process is to make the lower resist film thick enough to withstand etching, and the upper resist film or intermediate film to be thick enough to allow etching, thereby achieving the required functionality of the resist. The purpose of this method is to functionally separate the lower resist film and other layers, thereby forming a resist pattern with high resolution and excellent etching resistance.

[Problem that the invention seeks to solve]

The present inventors attempted a multilayer resist process using electron beam exposure, and conducted experiments on the following multilayer resist.

(1) Upper resist film...PMSS...
・0.2μm lower resist film...0FPR-800・
...2.0 μm PMSS refers to silylated polymethylsesquioxane, which is a material with high resistance to Ot plasma etching. 0FPR-800 is a novolak resist manufactured by Tokyo Ohka, and is often used for A1 etching.

(2) Upper resist film...PMSS...
・0.2μm lower resist film...CMR-100...
・2.0 μm CMR-100 is PMM made by Fujitsu Laboratories.
It is a type resist.

(3) Upper resist film...CMS...
0.5μm interlayer film・・・・・・・・・・・・5i
Oz......0.2μm lower resist film...
-0FPR-800...2.0μmCMS is chloromethylated polystyrene.

(4) Upper resist film...CMR-100...0.
5μm interlayer film・・・・・・・・・・・・5i(h
......0.2μm lower resist film...0
FPR-800...2.0μm As a result of experiments on these multilayer resists, 0FPR-800 and CMR-10
When an organic resist such as No. 0 was used and the upper resist film and intermediate film were exposed by electron beam exposure, a charge-up phenomenon occurred. That is, when an electron beam is scanned onto a resist film for exposure, the electrons irradiated onto the resist film by the previous scan remain in the resist film and exert a repulsive force on the electron beam during scanning, causing the electron beam to be bent. , and alignment mark detection failures and pattern positional deviations occurred. Note that the lower layer film was etched by oxygen plasma etching using the upper resist film and the intermediate film as masks.

-Finally, 0FPR is used as the lower resist film.
Organic films such as -800 and CMR-100 do not have very good etching resistance against chlorine-based dry etching agents, so the film thickness of 2.0 μm adopted in the experiment as the lower resist film is insufficient for chlorine-based dry etching. and
A film thickness of about 4 μm is required.

Such a high aspect ratio resist film causes pattern collapse and non-uniform etching of fine pattern portions.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for forming a pattern using a resist that does not cause a charge-up phenomenon during exposure using a charged medium and has excellent etching resistance.

[Means for solving problems]

The inventors of the present invention have discovered that aromatic vinyl compound polymers are materials that do not cause a charge-up phenomenon when exposed to charged media and have excellent etching resistance, but there are new problems to be solved. One point is that aromatic vinyl compound polymers are substances that are normally used as negative resists, so if they are used as a lower resist film, there is a problem with the solubility of the lower resist film when the upper resist film or intermediate film is applied. I discovered something.

As a means to solve this problem, when the aromatic vinyl compound polymer is irradiated with far ultraviolet rays, charged particle beams (electron beams, ion beams, etc.), We devised a method to make it insoluble in (resist).

In the present invention, the aromatic vinyl compound polymer includes:
Polymers of vinyl and benzene, toluene, xylene, ethylbenzene, paraterphenyl, diphenylmethane, styrene, propylbenzene, benzoic acid, etc., which can be used as negative resists, can be used. A preferred aromatic vinyl compound polymer in which the charge-up phenomenon is particularly suppressed is one in which a portion of the vinyl groups are substituted with halogen, particularly chlorine. The aromatic vinyl compound polymer is applied to the substrate as a lower resist film. The thickness depends on the material to be etched, but in the case of an etching-resistant Al-Cu alloy, it is 2 μm or less. Such a thin film thickness is possible because the aromatic vinyl compound polymer irradiated with ultraviolet rays or the like has high etching resistance against the etchant of the underlying substrate.

As the upper resist film, any upper resist film or intermediate film used in a known multilayer resist process can be used. That is, even if the materials of the upper layer and the intermediate film have charge-up properties due to the action of the underlying aromatic vinyl compound polymer, the charge-amplification properties of the resist film as a whole are reduced. However, if the upper resist film becomes too thick, it is not preferable not only from the viewpoint of charge-up properties but also from the viewpoint of resolution.

Therefore, it is preferable that the thickness of the upper resist film (including the intermediate film) be as thin as possible, determined from conditions such as pinholes and etching selectivity of the lower film. When applied to the increasingly popular two-layer resist method in which a silicon-containing polymer resist is used as the upper resist film, the film thickness can be reduced due to the excellent oxygen etching resistance of the silicon-containing polymer resist, and the aromatic vinyl compound polymer can be used to reduce the film thickness. As a result, it is expected that fine patterns with a small aspect ratio will be formed, and fine patterns made of etching-resistant materials will also be easily formed.

The upper resist film (including the intermediate film) is patterned by exposure to charged particles such as electron beams and ion beams.

The present invention will be explained in detail below.

〔Example〕

! Ribunjo CMS (chloromethylated polystyrene) was applied to an aluminum substrate to a thickness of 2.0 μm, and 100t:, 20
Bake under conditions of 5 minutes and deep ultraviolet light (Xe-Hg lamp, 5 minutes).
00W) for 20 seconds. Next, convert PMSS to CMS
It was coated to a thickness of 0.2 pm, incubated for 80 minutes in Cl2O, and exposed to an electron beam (20 kV) for 5X.
A predetermined pattern was exposed at an exposure dose of 10-6 C/cd. Subsequently, MiBK (methyl isobutyl ketone) Nihatane was dipped for 1 minute, and then IPA (isopropyl alcohol) was dipped for 30 seconds and rinsed. Finally, a plasma etching device (RF power 300W, 0
x-100sec11. Etching was performed at a pressure of -0.02 torr) to form a pattern with 0.3 μm lines and 0.3 μm spaces.

Using this pattern, an Al-2% Cu alloy film (thickness - 1 μm) was deposited using a plasma device (rr power 400 W% 5i
C14100sccn-, CI 2-303CC11
% pressure 'jJ -0.02 torr) for 4 minutes. Etching was possible under these conditions, and the amount of resist ashing was 1.2 μm for CMS. Further, the pattern deviation was 0.10 μm or less.

1 Lid 1 α-M CMS (Toyo Sodako) on an aluminum substrate 2
．． Coat it to a thickness of 0 μm, betatize it at 100°C for 20 minutes, and heat it with deep ultraviolet light (Xe-Hg lamp, 500W) for 2 hours.
Exposed to light. Next, PMSS was converted into α-M CMS by 0.2
It was coated to a thickness of 100 pm and betatized at 80° C. for 20 minutes. Thereafter, electron beam exposure was performed under the same conditions as in Example 1, and the MiB was subjected to IPA dip and plasma etching to form a pattern of 0.3 μm lines and 0.3 μm spaces.

Sm CMS was coated on an aluminum substrate to a thickness of 2.0 μm, betatized at 100°C for 20 minutes, and then exposed to far ultraviolet light (Xe
-Hg lamp, 500W) for 20 seconds. next,
Apply OCD (Tokyo Ohka) to CMS to a thickness of 0.2 μm and bake at 200°C for 20 minutes, then apply CMS to a thickness of 0.5 μm and bake at 100°C for 20 minutes. Prebaked with
X 10-'C/a! A predetermined pattern was exposed with an exposure amount of I. Furthermore, it was developed with acetone/IPA=10/1 (capacity ratio) for 60 seconds, developed with IPA for 30 seconds, and then processed with a plasma etching device (RF power 300W, C
F, -2003CC1ms pressure car (0.3 torr) was used to etch the OCD of the interlayer film for 2 minutes. Finally, a plasma etching device (RF power 300W, Ox −
Etching was carried out at 100 scci, pressure -0.02 torr) to form a pattern with 0.3 pm lines and 0.3 .mu.m spaces.

1 difference ■↓ This example is almost the same as Example 3 except that the second layer resist CMR-100 was used.

CMS was coated on an aluminum substrate to a thickness of 2.0 μm, betatized at 100°C for 20 minutes, and exposed to far ultraviolet light (Xe
-Hg lamp, 500W) for 20 seconds. next,
OCD was applied to a thickness of 0.2 μm, beta-coated at 200°C for 20 minutes, and C-gate R-100 was applied to a thickness of 0.5 μm.
It was coated to a thickness of
A predetermined pattern was exposed at an exposure amount of d. Furthermore, Mi
The sample was dipped for 60 seconds at a ratio of BK/acetic acid ≠ 1/1 (volume ratio), and then plasma etching and RF etching were performed in the same manner as in Example 3.

Northern flame 1.0 μm Al-2% Cu (upper layer) / S i Oz
(Intermediate layer)/Sin, wafer (substrate) with PR-Bo
E-beam resist was applied to a thickness of 2.0 μm and beta-baked at 200°C for 30 minutes. PMSS resist was applied to a thickness of 0.2 μm and beta-baked at 80°C for 20 minutes.
(20kV) at 5X 10-6C/c#)+flt
A predetermined pattern was exposed. Furthermore, subsequently, MiB
The pattern was dipped in garlic for 1 minute, then 30 seconds in IPA and rinsed. Finally, a plasma etching device (RF power 300W, 0202-1O0sc,
Etching was performed for 5 minutes at a pressure of -0.02 torr to form a pattern of 0.3 μm lines and 0.3 μm spaces.

Using this pattern, an A1-2% Cu alloy film (1 μm thick) was deposited using a plasma device (RF power 400 W, S
iSiCl4-100sc, C1z 30scc
When etching was carried out for 4 minutes at a pressure of 0.02 torr (ms pressure) for 4 minutes, the resist was etched before the alloy film was etched, and the resist did not function as a mask.

reference collection A resist pattern was formed in the same manner as in Comparative Example 1.

However, the thickness of the lower layer 0FPR-800 was set to 4.0 μm, and plasma etching (oxygen reactive ion etching) was performed.
was carried out for 10 minutes. As a result, 0.7 μm line, 0
．． A pattern with a 7 μm space was formed, and the resolution was lower than in Comparative Example 1.

Using this pattern, an Al-2% Cu alloy film (thickness - 1 μm) was etched. Plasma device (RF bar'7
400W, 5iCIa 101005c,
When etching was performed for 4 minutes at C1z-3Qsccm, pressure -0, 02 torr), the alloy film was etched. Further, the amount of ashing of the resist was 0FPR2.5 μm.

Uratane Charcoal i The same method as in Example 1 was carried out by changing the chloromethylation rate of CMS to 0.15.30% and 50.90% (however, the molecular weight was kept constant at 20,000). We investigated the relationship between rate and charge-up amount. The amount of charge-up was evaluated by the deviation (μm) from the reference pattern. The results are shown in the table below.

(Margin below) Table 1 [Effects of the Invention] Since the lower layer film of the pattern formed according to the present invention is a film with excellent etching resistance, the actual film thickness may be thinner than that of the conventional film, and pattern collapse may occur. Also, there is no problem of pattern shift due to the charge amplifier phenomenon during exposure of the upper resist film.

Claims (1)

[Claims] 1. In a pattern forming method using a multilayer resist process, a negative resist made of an aromatic vinyl compound polymer is applied to a substrate, and the lower layer is irradiated with deep ultraviolet rays, charged particle beams, or X-rays. A pattern forming method, which is used as a film, and is characterized in that one or two upper layers are exposed to a charged particle beam. 2. The pattern forming method according to claim 1, wherein the upper layer film is a layer of silicon-containing polymer. 3. The pattern forming method according to claim 2, wherein the aromatic vinyl compound polymer is vinyl polystyrene. 4. The pattern forming method according to any one of claims 1 to 3, wherein a portion of the vinyl groups of the aromatic vinyl compound polymer are substituted with halogen.