JPS5876829A - Low molecular weight resist of high resolution - Google Patents

Abstract

PURPOSE:To decrease swelling and dissolving phenomena by developing solns. and to improve resolution by decreasing the weight average mol.wt. of cyclized rubber and decreasing the degrees of dispersion of mol.wt. CONSTITUTION:The weight average mol.wt. of cyclized polyisoprene or cyclized polybutadiene is decreased to 10,000-50,000, whereby the degrees of dispersion of mol.wt., that is, the ratio of weight average mol.wt./number average mol.wt. is decreased to about 1.2-1.4. In the case of UV sensitive resist, a compsn. consisting of (a) 2-10% a cross-linking agent or a sensitizer, (b) 0.1-10wt% a stabilizer and (c) the balance the above-mentioned cyclized rubber is used, and in the case of far UV, X-rays and electron ray sensitive resist, a compsn. consisting of 2-30wt% (a), and 0.1-30wt% (b) is used. An arom. monocyclic hydrocarbon such as xylene is used for the solvent that dissolves said solid components (a), (b), (c), whereby the resist compsn. is prepd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the composition of a cyclized rubber resist.

Cyclized rubber-based resists are made by cyclizing raw material rubber such as isoprene using a catalyst, and then using a crosslinking agent that is activated by ultraviolet light, etc.
A negative type that contains a sensitizer and a stabilizer against dim light, oxygen, heat, etc., and is dissolved in a solvent such as xylene. When exposed to ultraviolet rays, etc., the exposed area undergoes a crosslinking reaction and polymerizes. It is a resist of.

However, cyclized rubber-based resists have the advantage of good adhesion to the substrate and no defects due to brittleness, but if the resist is developed and rinsed with an organic solvent after exposure, development swelling occurs, resulting in a positive type. There was a problem that the resolution was poor compared to resist.

In order to improve this problem, we changed the developer solution from one based on xylene to a developer with 5 to 1 carbon atoms, such as heptane, which has less swelling.
Attempts have been made to change to aliphatic hydrocarbons (2) and to change from wet development to dry development, which does not cause development swelling, although this has not yet become practical. The present invention does not improve the developer or the developing method, but rather improves the resist material itself, and aims to provide a cyclized rubber resist with improved resolution by reducing development swelling.

That is, the present invention consists of a solid component and a solvent, and the solid components include (a) 2 to 10% by weight of a crosslinking agent and/or sensitizer, (b) 0.1 to 10% by weight of a stabilizer, and (c) An ultraviolet-sensitive resist comprising the remaining amount of cyclized polyisoprene and/or cyclized polybutadiene having a weight average molecular weight of io, ooo to 50,000; The amount of the crosslinking agent and/or sensitizer in b) is 2 to 30% by weight of the solid component, and the crosslinking agent and sensitizer are those activated by deep ultraviolet rays, X-rays, and electron beams, and the stabilizer in ←) This resist is sensitive to deep ultraviolet rays, X-rays, and electron beams, and differs from the above-mentioned ultraviolet-sensitive resists in that the amount is 01 to 30% by weight of the solid components.

The cyclized rubber used in the resist of the present invention must have a weight average molecular weight in the range of io, ooo to 50,000. The weight average molecular weight is determined by gel permeation chromatography. The weight average molecular weight of conventional resists is ioo, ooo ~ 200
, 000, and when its molecular chain length is observed under an electron microscope, it is approximately 0.03 to 0.5 μm. And the molecular chain length of the resist made from synthetic polyisoprene is 0.
．． The molecular chain lengths are relatively uniform at about 3 to 0.5 μm, but those made from natural rubber have even more uneven molecular chain lengths.

In contrast, the cyclized rubber of the present invention has a weight average molecular weight of 10
,000 to 50,000, the molecular chain length is as short as about 0.1 to 0.2 μm.

As shown in FIG. 1, when the photoresist film 2 coated on the wafer 1 is exposed to ultraviolet light (arrow) through a photomask 6, the cyclized rubber polymer (solid line) is crosslinked in the crosslinking reaction area 4. (dotted line) and polymerizes into macromolecules and potassium,
In the uncrosslinked portion 5, the cyclized rubber polymer (solid line) does not cause crosslinking. When this photoresist film 2 is developed, the non-crosslinked polymer in the uncrosslinked part 5 is dissolved and removed, but the crosslinked polymer whose one end is in the crosslinking reaction part 4 is left behind and protrudes by the length of the molecular chain, resulting in jagged edges. The resulting pattern lines are developed. If the turn width is too narrow and the cyclized rubber polymers protruding from the left and right sides are connected, pacooning will not be possible. The resist of the present invention is
Since the molecular chain length is short, extremely sharp pattern images can be obtained and resolution can be improved.

Next, the present invention will be described in detail with regard to development swelling, which is a major factor that deteriorates resolution in cyclized rubber resists. The development reaction of a cyclized rubber resist is a swelling and dissolving phenomenon caused by a developer. Swelling occurs due to force diffusion caused by the difference in concentration of the developer in the resist, and the concentration of the developer in the resist remains constant (c).

The swelling phenomenon will not stop until this happens. As in the present invention, if the average molecular weight (M) of the cyclized rubber is made small, that is, the molecular weight is made low, the swelling amount Q can be calculated using the formula % formula % (: interaction coefficient of solvent, ρ,: density of the polymer ,■,: molar volume of solvent).

Furthermore, by reducing the weight average molecular weight of the cyclized rubber, the molecular weight dispersion range can generally be reduced. The degree of dispersion is the ratio of weight average molecular weight/number average molecular weight (MW
/MN). The W/MN of conventional resists was about 2.0 to 2.5, but the MW/MN of the resist of the present invention was about 1.2 to 1.4, which is an improvement in dispersion compared to conventional resists. In particular, a resist made by cyclizing a half-cloth polyisoprene rubber produced by anionic polymerization as a raw material is desirable because it has an extremely good dispersion degree.The better the dispersion degree, the fewer the long molecular chain lengths. Furthermore, the amount of high-molecular-weight materials that cause large swelling is reduced, and a resist with high resolution can be obtained.

Raw materials that can be used as cyclized rubber include polyisoprene rubber and polybutadiene rubber. The cyclization can be carried out using a catalyst such as sulfuric acid, para-toluenesulfonyl chloride, or tin chloride.

The crosslinking agent is a bisazide compound such as 2,6-di(4'-azidobenzal)4-methylchlorhexanone, and the stabilizer is 4,4'-butylidenebis-(6-t-butyl-η).
1-Cresol);
Compounds that provide stability against oxidation are used. As the sensitizer, a compound capable of expanding the sensitive wavelength range or increasing the ratio of the photosensitive density to the exposure amount is used.

In the case of ultraviolet-sensitive photoresists, the amount of crosslinking agent/sensitizer is 2 to 101% by weight of the solid components consisting of cyclized rubber, crosslinking agent, sensitizer, and stabilizer. ,
In the case of X-ray and electron beam-sensitive resists, the amount is determined to be 2 to 30% by weight of the solid components, taking into consideration photosensitivity and deterioration of resist performance. The stabilizer is added in an amount depending on the amount of the crosslinking agent and sensitizer. Although the remaining amount of the solid component is occupied by the cyclized rubber, there is no problem in blending some auxiliary materials that exhibit the desired performance. The amount of the crosslinking agent of the present invention is preferably slightly larger than that of conventional resists.

The solvent for dissolving the solid component may be one containing an aromatic monocyclic hydrocarbon such as xylene as a main component.

According to the resist of the present invention, since the cyclized rubber has a low molecular weight and its degree of dispersion is small, the molecular chain length is short and there is little swelling, and the resolution of the conventional resist, which was about 3μ711, is reduced to 2μ.
The resolution can be improved by about 1 μm. Also,
The coating film is sufficiently thick, and the sensitivity is comparable to conventional products.

Examples of the present invention and their effects will be specifically described below.

Example Synthetic polyimprene was cyclized to give an unsaturation degree of 7.1%, weight average molecular weight MW 40,900, number average molecular weight IN 34,500, dispersity MW/MN 1,1.
9 cyclized polyisoprene was added to 4. 14.0 parts by weight of this cyclized polyimrene (hereinafter "parts" are parts by weight), 2.6 parts by weight
-G(4'-azidobenzal)-4-methylcyclohexanone (3.4 parts) and 1.0 parts of phenolic stabilizer were dissolved in 81.4 parts of xylene to obtain a UV-sensitive resist of 18.60P at 25°C. .

A commercially available cyclized polyisoprene resist was used as a comparative example. This cyclized polyisoprene has a degree of unsaturation of 6.9% and a Mw
149,000, MN 65,000, MW/MN2
．． It was 28. The crosslinking agent concentration was 2.8% by weight, the solid component content was 13.1% by weight, and the resist had a viscosity of 60 cP at 25°C.

To compare the resolution of this example and the comparative example, a resist was coated on the wafer to a thickness of 1.0 μm, and the resolution was 1.50 μm.
1.75, 2.0, 2.5, 3.0, 3.5
, when patterned with a 4 μm wide test pattern, a comparative example (the one with the highest resolution among commercially available products)
The minimum resolution is about 3.0 μm, and if the size is smaller than this, the pattern is distorted or linearity cannot be obtained. On the other hand, the minimum resolution of the example is 2.0 μm,
An improvement in resolution of approximately 1.0 μm was achieved.

Regarding the thickness of the coating film, although the photoresist of the example is a low molecular weight resist, a coating film thickness of approximately 1.15 μm was obtained using a spin coater with a rotation speed of 4000 rpm, and there were no problems in practical terms. Ta. The sensitivity was also evaluated using a mask aligner PLA and a 500 F (manufactured by Canon) integrating exposure meter, and the coating film thickness was 1.0μ2n.
It can be seen that the sensitivity shown in Figure 2 is obtained when , and there is no practical problem at all. Regarding this point, it is common that the sensitivity decreases as the molecular weight of the polymer decreases.
It is believed that the resist of the present invention has a narrow molecular weight distribution and therefore has high sensitivity. Next, as shown in FIG. 2, the residual film rate after development in the light irradiated area is also the same as that of conventional photoresists, indicating that it is a practical photoresist.

Next, we will compare the γ value, which is often used as a measure of resolution. The γ value is 1, the horizontal axis is the exposure energy, and the vertical axis is the film thickness after development/remaining ratio of coated film thickness, and the slope of the linear slope is the slope of the linear slope, which is the exposure energy of the residual film ratio. Show dependencies. The larger the γ value, the higher the resolution. FIG. 2 shows the characteristic curve of the example with a coating film thickness of 1.0 μm, and FIG. 6 shows the same characteristic curve of the comparative example. As shown in Figures 2 and 6, the γ value of the commercially available comparative example is 1.67, while that of the example is 5.25, and from this point of view, the resist of the present invention has an extremely high γ value. It can be seen that the resolution is high.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the relationship between molecular chain length and resolution during resist development, Fig. 2 is a graph showing the characteristic curve of the example, and Fig. 3 is a graph showing the characteristic curve of the example.
The figure is a graph showing a characteristic curve of a comparative example. 2... Resist film, 4... Crosslinked reaction part, 5... Uncrosslinked part. Patent applicant Tokyo Shibaura Electric Co., Ltd. Agent Patent attorney Eiji Morota Figure 1

Claims (1)

[Scope of Claims] 1 Consists of a solid component and a solvent, as solid components: (a) 2 to 10% by weight of a crosslinking agent and/or sensitizer;
b) 0.1 to 10% by weight of a stabilizer, and C) the remaining amount of cyclized polyisoprene and/or cyclized polybutadiene having a weight average molecular weight of 10,000 to 50,000. Sex resist. 2 Consists of a solid component and a solvent, as solid components: (a) 2 to 30% by weight of a crosslinking agent and/or sensitizer;
b) 0.1 to 30% by weight of a stabilizer, and (c) a residual amount of cyclized polyisoprene and/or cyclized polybutadiene having a weight average molecular weight of 10,000 to so, doo. UV, X-ray and electron beam sensitive resists.