JP2786502B2 - Resist material - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a resist material, and more particularly to a resist material suitable for use as an upper layer of a two-layer resist method.

(Prior Art) With the high integration of LSIs, a fine resist pattern is required to enable the manufacture thereof.

Electron beam lithography using an electron beam as a source and X-ray lithography using an X-ray as a source have been proposed as lithography techniques for obtaining a fine resist pattern having a rule of 0.5 μm or less. However, electron beam lithography, X
At present, in consideration of the throughput, apparatus perfection and cost of each line lithography, transfer lithography using light is desirable.

Therefore, various means have been taken in optical lithography in order to obtain submicron resolution.

One such means is to shorten the wavelength of the light source. Optical lithography using far ultraviolet light having a wavelength of 200 to 300 nm as a light source, such as laser lithography using a KrF excimer laser, is most expected.

Another means is to increase the numerical aperture (NA) of the lens of the exposure apparatus. However, when the NA is increased, the depth of focus of the exposure apparatus becomes increasingly shallow, which causes a new problem that a single-layer resist cannot form a good resist pattern on a semiconductor substrate having a step. Occurs.

In order to solve this, a multilayer resist method has been proposed. In particular, the two-layer resist method is expected because the process is simple. Hereinafter, FIG. 2 (A)
The two-layer resist method will be briefly described with reference to FIGS. 2 (A) to 2 (C) are process diagrams of a two-layer resist method shown in cross-sectional views.

First, the lower layer 13 having a large thickness is formed on the substrate 11 having the step 11a.
Is formed. The substrate 11 is planarized by the lower layer 13. As a constituent material of the lower layer 13, a polymer is used.

After heat treatment of the lower layer 13, an upper layer 15 is formed on the lower layer 13 (FIG. 2 (A)).

Next, the upper layer 15 is exposed and developed to form an upper layer pattern 15a (FIG. 2B).

Next, O ₂ -RIE is performed using this upper layer pattern 15a as a mask.
The lower layer 13 is etched by (oxygen reactive ion etching) to form a resist pattern 17 composed of the upper layer pattern 15a and the lower layer pattern 13a (FIG. 2C).

As is clear from the above description, the upper layer in the two-layer resist method needs to have not only the function of the image layer but also the function of an etching mask layer when etching the lower layer. Therefore, the upper layer is required not only to have high resolution and high sensitivity as a resist but also to have high O ₂ -RIE resistance.

As a resist material satisfying such conditions, for example, there is a silicon (Si) -containing resist disclosed in a literature (Polymer 37, June, 1988). According to this resist material, Si contained therein reacts with oxygen plasma to form an SiO ₂ film on the resist surface, thereby obtaining O ₂ -RIE resistance.

According to this document, the silicon content is important in this type of resist material, and 10 wt% or more of Si is necessary to obtain practical O ₂ -RIE resistance. As a method of constructing the resist, a method of introducing a Si group into the resist structure and a method of adding a reactive group to a silicon-based polymer to form a resist are disclosed. Further, as a silicon-containing resist material sensitive to far ultraviolet rays, a material containing a base resin represented by the following or a photosensitive agent and a material represented by the following formula are shown.

(Problems to be Solved by the Invention) However, some conventional silicon-containing resists have low O ₂ -RIE resistance due to low silicon content, and are themselves etched to some extent when etching the lower layer. For this reason, a phenomenon occurs in which the final resist pattern dimension is reduced.

In addition, some conventional silicon-containing resists have low heat resistance and diffuse into the lower resist. Therefore, the region in which the underlying silicon-containing resist has diffused is difficult to be etched, which may cause patterning failure.

Any of the phenomena described above causes a reduction in the resolving power in the two-layer resist method.

In addition, conventional silicon-containing resists have not always had satisfactory resolution and sensitivity.

The present invention has been made in view of such a point,
Therefore, an object of the present invention is to solve the problem of low O ₂ -RIE resistance and low heat resistance, and to provide a resist material having high resolution and high sensitivity.

(Means for Solving the Problems) In order to achieve this object, according to the resist composition of the present invention, a silylated product containing a vinyl group of chrysotile and benzoin, benzyl, and benzoyl peroxide as photosensitizers are used. A benzoin compound represented by the following formula,
A benzoin compound represented by the following formula, a benzyl compound represented by the following formula, a benzyl compound represented by the following formula, and 3,3 ′, 4,4′tetrakis (t-butylperoxycarbonyl) benzophenone It is characterized by containing more than one kind of substance.

In practicing the present invention, it is preferable that the above-mentioned silylated product is dimethylvinylsilyl ether of chrysotile.

(Operation) According to such a configuration, an operation as described below is obtained.

Since the silylated product containing vinyl groups chrysotile containing a large amount of silicon (containing 45 wt% As far the embodiment) As is apparent from the experiments described below, the resist material having excellent O ₂ -RIE resistant Is obtained.

Further, since the silylation product contains a vinyl group, the molecular weight of the light-irradiated portion of the resist material increases due to the action of the vinyl group and the photosensitizer, so that the resist material becomes insoluble in a developer and can be patterned.

Further, since the silylation product has high heat resistance, the resist material is unlikely to diffuse into the lower layer. Further, this resist material contains a predetermined substance such as benzoin, benzyl, benzoyl peroxide or the like as a photosensitive agent. All of these substances generate radicals with far ultraviolet rays. Therefore, according to the present invention, a novel resist material that uses chrysotile, has a large silicon content, and is sensitive to far ultraviolet rays is realized.

(Examples) Hereinafter, examples of the resist material of the present invention will be described. It should be understood that the names of the chemicals used and the numerical conditions such as the mixing amount, film thickness, temperature, time and the like described in the following description are merely examples within the scope of the present invention.

Example 1 Synthesis Example of Silylation Product First, a silylation product containing a vinyl group, which is a silylation product of a clay mineral contained in a resist material, is synthesized as described below. In this embodiment, chrysotile, which is a kind of serpentine, is used as the clay mineral.

First, 80 g of chrysotile was added to 6 M (mol) of HCl (hydrochloric acid) 60.
The hydrochloric acid is stirred at a temperature of 50 ° C. for 12 hours to decompose chrysotile. Thereafter, undecomposed matter is recovered by centrifugation, washed with water and dried to obtain 32 g of a residue.

Next, at room temperature, 8 g of the residue is taken up in 100 ml of 0.8 M NaOH (sodium hydroxide), after which the NaOH is
Stir for hours.

Next, the insoluble portion is separated by filtration, the filtrate is neutralized, and extracted with THF (tetrahydrofuran). Then, add 0.
After dropwise addition of a mixture of 233M dimethylvinylchlorosilane and 100 ml of THF, the extracted solution is stirred for 1 hour.

Next, hexane is added to the solution after stirring, and then the organic layer is separated. This organic layer is washed with water and the organic solvent is removed to obtain a crude product.

Next, the crude product is dissolved in acetone, and water is added to the crude product for reprecipitation for purification. By repeating such a purification operation several times, dimethylvinylilisilyl ether of chrysotile (hereinafter sometimes abbreviated as SCMR).
Get.

 The SCMR obtained by the synthesis was a white powder.

The weight average molecular weight of the SCMR obtained by this synthesis was 5,
The number average molecular weight was 300 and 3,200.

 The results of elementary analysis of this SCMR were as follows: Si = 45.0% by weight, H = 5.1% by weight, C = 27.2% by weight, and O = 22.7% by weight.

A thermal analysis of this SCMR showed that
No change in TG (weight change) up to 0 ° C, DS up to 270 ° C
It was found that there was no change in C (Differential Scanning Calorimeter).

Description of the resist material of Example 1 10 g of the above-mentioned SCMR and 1 g of benzoin (shown by the following formula) as a photosensitizer that generates radicals by far ultraviolet rays
And dissolved in 100 ml of isoamyl alcohol,
The solution is filtered using a 0.2 μm filter to prepare a coating solution of the resist material of Example 1.

... Patterning experiment (part 1) Next, on a (100) surface of a silicon wafer having a diameter of 3 inches (1 inch is about 2.54 cm), a MP-1400 (a photoresist manufactured by Shipley) as a lower layer was formed to a thickness of 1.5 μm. Coat thick. Thereafter, the silicon wafer is baked at a temperature of 200 ° C. for 5 minutes using a hot plate.

Next, the resist material of Example 1 is coated on the baked lower layer to a thickness of 0.2 μm. Then, the silicon wafer is heated at 80 ° C. for 1 hour using a hot plate.
Bake for a minute.

Next, the baked resist material of Example 1 was exposed through a test mask having various line and space patterns at a dose of 100 mJ / cm ² using a contact aligner having a 500 W Xe-Hg lamp. Perform Next, this sample was diluted with isopropyl alcohol.
Develop for 1 minute at a temperature of ° C. Observation of the obtained upper layer resist pattern (the pattern of the resist material of Example 1) with a scanning electron microscope (SEM) revealed that a 0.5 μm line and space pattern was resolved.

Next, using the upper resist pattern as a mask, the O ₂ flow rate was set to 20 sccm, and the gas pressure was set to 20 mm using a parallel plate type reactive ion etching apparatus (D451 manufactured by Nidec Anelva Co., Ltd.).
The lower layer MP-1400 is etched under the conditions of 1 Pa, a power density of 0.15 W / cm ² , and an etching time of 20 minutes.

Observation by SEM of the sample after the etching of the lower layer was completed revealed that a resist pattern having a line and space pattern of 0.5 μm and a film thickness of 1.7 μm was obtained. Needless to say, the obtained resist pattern was rectangular.

... Patterning experiment (Part 2) A patterning experiment is performed in the same procedure as the above-mentioned patterning experiment (Part 1) except that the exposure apparatus is a KrF excimer laser stepper with NA = 0.35 and the dose is 130 mJ / cm ^2. .

Observation of the resulting resist pattern by SEM showed that the film thickness was 0.35 μm line and space pattern.
It was found that a 1.7 μm resist pattern was obtained. Needless to say, the obtained resist pattern was rectangular.

… Description of O ₂ -RIE resistance Using a parallel plate type reactive ion etching device D451, O ₂ flow rate is 20sccm, gas pressure is 1Pa, current density is 0.15W
/ cm ² and the resist material of Example 1 and MP-1400
Etching the respective baking already coating measures the O ₂ -RIE resistance both from the etching amount for the etching time. FIG. 1 is a characteristic diagram showing the results, with the horizontal axis representing the etching time (minutes) and the vertical axis representing the etching amount (μm). In FIG. 1, what is indicated by I is the characteristic of the resist material of the first embodiment, and what is indicated by II is the characteristic of MP-1400.

As can be understood from FIG. 1, the O ₂ -RIE resistance of the resist material of the first embodiment is 50 times or more as compared with that of MP-1400.

Example 2 A coating solution of the resist material of Example 2 was prepared in the same manner as in Example 1 except that the sensitizer was changed to benzyl (shown by the following formula) instead of benzoin of Example 1. .

Further, using the resist material of the second embodiment, a patterning experiment using a Xe-Hg lamp and a D451RIE apparatus is performed in the same procedure as in the first embodiment.

It was also found that a resist pattern having the same resolution as that of Example 1 was obtained with the resist material of Example 2.

Example 3 A coating solution of the resist material of Example 3 was prepared in the same manner as in Example 1 except that the photosensitive agent was changed to 0.1 g of benzoyl peroxide instead of benzoin of Example 1.
Further, using the resist material of the third embodiment, a patterning experiment using a Xe-Hg lamp and a D451RIE apparatus is performed in the same procedure as in the first embodiment. However, the dose at the time of exposure in the case of the resist material of Example 3 was required to be larger than that in Example 1, and was 300 mJ / cm ² .

It was found that a resist pattern having the same resolution as that of Example 1 can be obtained with the resist material of Example 3.

As is clear from the description of each embodiment described above, the resist material of this invention, it can be seen that is excellent in O ₂ -RIE resistance. Further, since a pattern on the order of submicrons can be obtained even without rinsing after development, it can be considered that swelling due to the developer does not occur, and it can be seen from this point that the resolution can be improved.

Also, it can be seen that when benzoin or benzyl is used as the photosensitizer, a resist material with higher sensitivity can be obtained than when benzoyl peroxide is used as the photosensitizer.

Although the embodiment of the resist material of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications as described below can be added.

For example, in the above-described embodiment, an SCMR having a weight average molecular weight of 5,300 and a number average molecular weight of 3,200 was used, but the SCMR that can be used is not limited to this molecular weight.

Further, in the above-described embodiment, dimethylvinylchlorosilane is used as a silylating agent when synthesizing a silylated product containing a vinyl group of chrysotile, but the silylka agent is not limited to this. However, in view of ease of synthesis, it is preferable that the silylating agent be a single-sensitive vinylchlorosilane represented by the following structural formula, which also contains the dimethylvinylchlorosilane used in the examples.

However, in the formula, R ₁ and R ₂ are an alkyl group, an alkoxy group,
Examples thereof include a vinyl group, an allyl group, and a phenyl group, which may be the same or different.

Further, in the above-described embodiment, in order to construct a resist material that is sensitive to far ultraviolet rays, the photosensitive agent is formed of benzoin, benzyl, or benzoin peroxide that generates radicals with far ultraviolet rays. However, the substance that generates radicals with far ultraviolet rays is not limited to this, and other substances may be used.
Examples of such a substance include a benzoin compound represented by the following formula or the formula, a benzyl compound represented by the following formula or the formula, or 3,3 ′,
4,4'tetrakis (t-butylperoxycarbonyl)
Benzophenone and the like can be mentioned.

Further, the resist material of the present invention can of course contain other substances for improving the properties of the resist, in addition to the silylation-generating portion containing a vinyl group of chrysotile and the photosensitive agent.

(Effect of the Invention) As is clear from the above description, since the resist material of the present invention uses a silylated product containing a vinyl group of chrysotile as a base, it has high O ₂ -RIE resistance and high heat resistance. It becomes a highly resistive material. Accordingly, the resolution of the two-layer resist method can be improved.

Further, since the resist material does not swell the pattern with the developing solution, the resolution of the resist material itself is improved.

Further, since a predetermined substance such as benzoin, benzyl, benzoyl peroxide or the like is contained as a photosensitive agent, a novel resist material using chrysotile, having a high silicon content, and being sensitive to far ultraviolet rays is realized.

Therefore, the resist material of the present invention can be used for forming a submicron pattern which is essential for manufacturing a highly integrated semiconductor device.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining O ₂ -RIE resistance, and FIGS. 2 (A) to 2 (C) are diagrams for explaining a two-layer resist method. 11 ... substrate, 11a ... step 13 ... lower layer, 13a ... lower layer pattern 15 ... upper layer, 15a ... upper layer pattern 17 ... resist pattern.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-279241 (JP, A) JP-A-1-105242 (JP, A) JP-A-63-317553 (JP, A) JP-A-62 215944 (JP, A) JP-A-60-238827 (JP, A) JP-A-61-264341 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03F 7/00-7 / 18

Claims (3)

(57) [Claims] 1. A silylated product containing a vinyl group of chrysotile, benzoin, benzyl, benzoyl peroxide, a benzoin compound represented by the following formula, a benzoin compound represented by the following formula, A benzyl compound represented by the following formula:
A resist material comprising at least one substance selected from 3,3 ', 4,4'tetrakis (t-butylperoxycarbonyl) benzophenone. 2. The resist material according to claim 1, wherein the silylation product is dimethylvinylsilyl ether of chrysotile. 3. The resist material according to claim 1, wherein said silylation product is dimethylvinylsilyl ether of chrysotile, and said photosensitizer is benzoin or benzyl.