JPH0572737A - Chemically amplified resist and method for manufacturing exposure mask using the same - Google Patents

Abstract

(57) [Summary] [Object] A first object of the present invention is to provide a highly sensitive resist. A second object of the present invention is to form a highly accurate energy absorber pattern. [Structure] In the present invention, a chemically amplified resist to which a neutral salt is added is used as the resist.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemically amplified resist and a method for manufacturing an exposure mask using the same, and more particularly to a composition of the chemically amplified resist.

[0002]

2. Description of the Related Art In recent years, as the demand for higher density and higher integration of semiconductor integrated circuits has increased, the pattern size has become smaller and smaller. In order to correspond to this miniaturized pattern size, the wavelength of light is short and X
Line lithography is being developed. Since X-ray lithography is the same size transfer and the size of the X-ray absorber pattern of the X-ray mask must be the same size as the element in the integrated circuit, the mask formation requires submicron-scale ultrafine processing technology. It is said that.

The formation of a resist pattern, which is one step in the manufacture of X-ray masks, requires the formation of an ultrafine pattern of the same size as the X-ray absorber, which is why the development of highly sensitive and high-resolution resist is required. Is desired.

At present, as a high-sensitivity resist for photoexposure or electron beam writing, research on a chemically amplified resist is active. Among them, a chemically amplified resist that utilizes an acid-catalyzed reaction is widely used.

This chemically amplified resist is composed of a resin, a cross-linking agent,
It consists of an acid generator. When irradiated with light, the resin in the resist acts as a photosensitizer and is excited. By exchanging electrons with the excited resin, halogen acid is generated from the acid generator. The generated acid acts as a catalyst for the crosslinking agent and diffuses while causing a crosslinking reaction. And this catalytic reaction is accelerated by heating. The regions thus crosslinked become insoluble in the alkaline developer and form a pattern.

The sensitivity of the chemically amplified resist is considerably improved as compared with the conventional resist. However, in forming an ultrafine resist pattern,
Various obstacles have occurred due to lack of sensitivity. Due to such lack of sensitivity, the resist is not sufficiently exposed and the developing speed is lowered in the lower part of the resist, so that the shape of the resist is not rectangular, or the base of the resist has a hem, etc. Is becoming As described above, there is room for improvement in current resists for the formation of ultrafine patterns, and development of highly sensitive and high resolution resists is desired.

[0007]

As described above, although the sensitivity has been improved by the appearance of the chemically amplified resist, even if the chemically amplified resist is used, there are various obstacles to the formation of the ultrafine pattern due to the lack of sensitivity. Has occurred.

The present invention has been made in view of the above circumstances, and improves the sensitivity of a chemically amplified resist, and
Furthermore, it aims at providing a highly accurate mask using this resist.

[0009]

Therefore, in the present invention, a neutral salt is added to the components of a chemically amplified resist utilizing an acid-catalyzed reaction to improve the sensitivity of the resist.

Further, according to the method of the present invention, a chemically amplified resist containing a resin, a cross-linking agent, an acid generator and a neutral salt is used as a resist for pattern formation when forming a mask pattern for selecting exposure light. After applying a resist, the chemically amplified resist is subjected to pattern exposure, heat treatment is performed, and then development is performed to use a resist pattern formed.

[0011]

The present inventors focused on the fact that the catalytic reaction is promoted by adding a neutral salt to the acid-catalyzed reaction system, and an appropriate amount was added to the components of the chemically amplified resist utilizing the acid-catalyzed reaction. Neutral salt was added. As a result, the catalytic reaction by the acid is promoted and the rate of the crosslinking reaction is increased, so that the sensitivity of the resist can be increased.

Further, according to the method of the present invention, in forming an energy absorber pattern of a mask for pattern exposure using exposure light such as X-rays or electron beam light, a chemically amplified resist utilizing an acid catalytic reaction is formed. Pattern exposure using a suitable amount of a neutral salt added to the component as a resist increases the rate of the cross-linking reaction and significantly improves the resist sensitivity, so that there is no vertical and dimensional error. A resist pattern can be formed, whereby a highly accurate mask can be formed.

The neutral salt used here is NaCl,
KCl, LiCl, BaCl ₂ , SnCl ₂ , NaNO
_It is desirable to use ₃ , KNO ₃ , Na ₂ SO _4, etc.

In addition, by adding a neutral salt, Na,
Contamination of the base substrate by K or the like does not cause any obstacle in the manufacture of the mask because the X-ray transmittance of Na, K and the like is high.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing a manufacturing process of an X-ray mask according to an embodiment of the present invention.

Here, the X-ray absorber pattern is formed by using a chemically amplified resist component utilizing an acid catalyst reaction to which a neutral salt is added.

In manufacturing, first, the high frequency heating type L
Using a PCVD device, coat the surface of the graphite with SiC.
Thickness of the coated susceptor with double-side polishing
A 3 inch Si substrate 1 having a surface orientation (100) of 0 μm is set, and the Si substrate is subjected to vapor phase etching with HC1 gas at 100 ° C. to remove the natural oxide film and the heavy metal contaminants existing on the Si substrate. Removed. This completes the surface mask cleaning process for the Si substrate.

Then, as shown in FIG. 1A, silane (SiH ₄ ) is used as a silicon raw material, acetylene (C ₂ H ₂ ) is used as a carbon raw material, hydrogen (H ₂ ) gas is used as a carrier gas, and hydrogen chloride ( HCl) while supplying
At a substrate temperature of 1100 ° C., a SiC film 2 is deposited on the Si substrate 1 by 1 μm.

After that, a Cr film 3 having a thickness of 0.1 μm was further deposited on the back surface of the Si substrate 1 by using a vacuum vapor deposition apparatus using an electron beam on the back surface of the Si substrate 1.

Then, as shown in FIG. 1B, a resist pattern 4 having an opening with a diameter of 20 mm in the central portion is formed by a normal photolithography technique.

Then, as shown in FIG. 1 (c), an opening was formed in the Cr film 3 by liquid phase etching using a cerium ammonium nitrate solution using the resist pattern 4 as a mask.

Thereafter, as shown in FIG. 1D, a W film 5 having a thickness of 0.5 μm is deposited as an X-ray absorber on the back surface side of the SiC film 2 using a magnetron DC sputtering device. Here, the sputtering condition is electric power of 1
The gas pressure was set to 3 mTorr at which the stress becomes 0 on the low pressure side where a W film having a high density can be formed.
The stress of the W film 5 thus formed is
As a result of measurement from the warp, it was 3 × 10 ⁷ N / m ² .
Next, Ar ions having an energy of 180 keV,
Ions are implanted at a dose of 3 × 10 ¹⁵ atoms / cm ² to reduce the stress to zero. After this, an Al ₂ O ₃ film 6 was deposited on the W film 5 by sputtering to a thickness of 50 nm.

Then, as shown in FIG. 1 (e), the reinforcing frame 7 made of silicon and the silicon substrate 1 serving as the mask support were directly bonded. At this time, the reinforcing frame 7 was held on a stage laid with a viton rubber having a thickness of 1 mm, which is an elastic body, and a pressure of 1.0 kg / cm ² was applied for 1 minute.

Next, as shown in FIG. 1 (f), on the W film 5,
As the electron beam resist 8, a chemically amplified resist called SAL601 containing 15% of NaCl was applied to a film thickness of 0.5 μm and heated to 130 ° C. in an N ₂ atmosphere to remove the solvent in the resist. Next, the resist 8 was drawn with an electron beam drawing device at a dose amount of 8 μC / cm ² . After heating to 130 ° C. in an N ₂ atmosphere to promote the acid-catalyzed reaction of the cross-linking agent, development was performed to form a desired pattern (minimum line width 0.15 μm).

Next, as shown in FIG. 1 (g), Cl ₂ + H ₂ was used as an etching gas by an ECR plasma etching apparatus, and Al ₂ O ₃ was used with the resist 8 as a mask.
Membrane 6 was etched.

Then, as shown in FIG. 1H, the W film 5 is patterned using the Al ₂ O ₃ film 6 as a mask by anisotropic etching using SF ₆ and CHF ₃ as etching gases. Applied power is 200
W and discharge pressure were 20 mTorr.

Next, as shown in FIG. 1 (i), a Cr film 3 was formed by using a potassium hydroxide solution having a concentration of 30% heated to 95 ° C.
Using the as a mask, the silicon substrate 1 was removed by etching in a liquid phase. This made it possible to form an opening having a diameter of 30 mm.

X of the X-ray mask formed by the above steps
When the shape of the linear absorber pattern was observed by SEM, 0.15 μm lines and spaces were satisfactorily formed and there was no edge roughness, resulting in a vertical W pattern. In addition, in order to measure the pattern positional deviation of the X-ray mask, the positional deviation between before and after the back etching of the cross pattern in the measurement area of 20 mm × 20 mm is measured by laser interference measurement called "light wave 3l" manufactured by Nikon Corporation. As a result of measuring with a detector, the detection limit is 0.01 μm (3σ)
We were able to achieve a significantly smaller value of

Next, in order to investigate the effect of the addition of the neutral salt, first, Na was added to the chemically amplified resist XP8843.
What added 0-30% of Cl was apply | coated to the silicon substrate surface so that it might become a film thickness of 5 micrometers.

Then, UV light having a wavelength of 313 nm is applied to this resist.
It was irradiated with light for 1 second, and the dissolution rate in the developing solution was measured.

The results are shown in FIG. From FIG. 2, it can be seen that the acid-catalyzed crosslinking reaction is accelerated by the addition of NaCl and reaches a maximum at a concentration of 10%.

By adding an appropriate amount of neutral salt in this way, the rate of the crosslinking reaction is increased, so that the resist sensitivity is significantly improved.

The present invention is not limited to the above embodiment. For example, the resist is not limited to the electron beam resist such as SAL601, but any chemically amplified resist utilizing an acid catalyzed reaction such as the light exposure resist XP8843 can be applied. The mask may be an X-ray mask, a photomask, an EB transfer mask, or another type. Furthermore, the present invention is not limited to the mask formation, and can be applied to other processing steps as long as it is a device manufacturing step or the like which is not affected by ions such as Na and K.

The neutral salt to be added is not limited to NaCl, and other neutral salts such as KCl may be used.

Furthermore, the X-ray absorber is not limited to W, but T
It is also possible to use a, Mo and their nitrides and carbides. Although a SiC film was used as the X-ray transparent thin film, S
An iN _x , BN, boron-doped Si substrate can be used.

In addition, various modifications can be made without departing from the scope of the present invention.

[0038]

As described above, according to the present invention, by adding a neutral salt to a chemically amplified resist, the sensitivity is significantly improved, and a vertical and dimensional error-free resist pattern is formed. This makes it possible to form a highly accurate mask.

[Brief description of drawings]

FIG. 1 is a diagram showing a manufacturing process of an X-ray mask according to an embodiment of the present invention.

FIG. 2 is a graph showing the results of measuring the relationship between the amount of neutral salt added and the resist dissolution rate according to the present invention.

[Explanation of symbols]

1 Si substrate 2 SiC film 3 Cr film 4 Resist pattern 5 W film 6 Al ₂ O ₃ film 7 Reinforcement frame 8 Electron beam resist

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location G03F 7/26 7124-2H H01L 21/027

Claims (2)

[Claims] 1. A chemically amplified resist containing a resin, a crosslinking agent, an acid generator and a neutral salt. 2. An absorber pattern forming step of forming a mask pattern for selecting exposure light on a mask support, wherein the mask pattern forming step comprises a resin as a pattern forming resist, and a cross-linking agent. ,
The method includes a coating step of coating a chemically amplified resist containing an acid generator and a neutral salt, an exposure step of pattern exposing the chemically amplified resist, a heat treatment step of heat treatment, and a development step. And a method for manufacturing an exposure mask.