JP3306288B2 - Method of forming resist pattern - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a resist pattern used in a semiconductor lithography element technology, and more particularly, to an acid-generating chemically amplified resist on a BPSG (silicon oxide film containing boron and phosphorus) base substrate. This is related to the pattern forming method.

[0002]

2. Description of the Related Art Positive acid-generating chemically amplified resists are:
It is constituted by introducing an acid generator and a dissolution inhibiting group into an alkali-soluble resin or adding a dissolution inhibitor. In the case of a positive-type acid-generating chemically amplified resist, a dissolution inhibiting group (agent) is decomposed by using an acid generated by exposure as a catalyst, and becomes alkali-soluble to obtain a positive pattern. On the other hand, a negative-type acid-generating chemically amplified resist is constituted by adding a crosslinking agent to an acid generator and an alkali-soluble resin. Negative-type acid-generating chemically amplified resist is a post-exposure bake (PEB) using an acid generated from a photosensitive acid generator upon exposure as a catalyst.
Occasionally cross-linking is insolubilized and a negative pattern is obtained by alkali development.

FIGS. 5A to 5E show a pattern forming method using the above-mentioned acid-generating chemically amplified positive resist. As shown in FIG. 5B, an acid-generating chemically amplified positive resist 51 is applied on a BPSG (silicon oxide film containing boron and phosphorus) base substrate 50, and is baked before exposure and selectively exposed. The light intensity due to this exposure is shown in FIG. 5A. An exposure portion 51A is formed according to the light intensity as shown in FIG. 5C. Next, when post-exposure bake (PEB) is performed, the solubilized portion 51a is formed as shown in FIG. 5D, and the solubilized portion 51a is dissolved by alkali development to form a pattern as shown in FIG. 5E.

FIGS. 6A to 6E show a pattern forming method using the above-mentioned acid-generating chemically amplified negative resist. As shown in FIG. 6B, after applying an acid generating chemical amplification type negative resist 61 on a BPSG base substrate 60, a pre-exposure bake is performed to selectively expose. FIG. 6A shows the light intensity due to this exposure. An exposed portion 61A is formed according to the light intensity as shown in FIG. 6C. Next, post-exposure bake (PE
By performing B), an insolubilized portion 61a is formed as shown in FIG. 6D, and a pattern is formed by alkali development as shown in FIG. 6E.

[0005]

However, in the above-described method of forming a resist pattern using an acid-generating chemically amplified resist, there is a problem in that the shape of the resist pattern is deteriorated due to the influence of the surface of the BPSG base substrate. FIG. 5E
As shown in FIG. 6, in the positive type, hem pulling occurs, and as shown in FIG. 6E, in the negative type, hem constriction occurs. As a result, when forming a fine pattern on a submicron level, there is a problem that controllability of the pattern dimension is poor.

An object of the present invention is to provide a method for improving the cross-sectional shape of a resist pattern using an acid-generating chemically amplified resist on a BPSG base substrate in order to solve the above problems.

[0007]

Means for solving the problems Japanese Patent Laid-Open No. 7-9 / 1990
No. 2694 reports that the abnormal shape of the bottom of the acid-generating chemically amplified resist on the SiN base substrate can be improved by subjecting the SiN base substrate to oxygen plasma treatment or forming a silicon oxide film. However, as a result of a study by the present inventors, it was found that the same effect as on a SiN undersubstrate could not be obtained on a BPSG undersubstrate.

Therefore, the present inventor studied a method of improving the cross-sectional shape of a resist pattern using an acidogenetic amplification resist on a BPSG base substrate, and reached the present invention.

The present invention relates to an acid-generating chemically amplified resist pattern.
A method of forming a sulfuric acid on a BPSG substrate.
Acid using any of acid, phosphoric acid, boric acid, or nitric acid
After cleaning, silicon oxide is placed on the BPSG substrate.
Film and then apply acid-generating chemically amplified resist
After selective exposure, bake after exposure and
Post-development to form a substantially vertical resist shape
It is characterized by.

The present invention also relates to the silicon oxide film.
The thickness is not less than 100 °.

Further , the present invention provides the above-mentioned silicon oxide film,
It is characterized by being formed using a CVD apparatus.

The following is a detailed description leading to the present invention.

In Japanese Unexamined Patent Publication No. Hei 7-92694, an abnormal shape of the bottom of an acid-generating chemically amplified resist on a Si undersubstrate or a SiN undersubstrate may be caused by subjecting the undersubstrate to oxygen plasma treatment or the undersubstrate. It is reported that improvement can be achieved by forming a silicon oxide film on a substrate. Thus, the BPSG substrate was treated with oxygen plasma to improve the shape of the acid-generating chemically amplified resist pattern, but no effect was obtained. On the other hand, when the SiN base substrate is treated with oxygen plasma,
The effect reported in the official gazette appeared. Next, the film thickness 30
シ リ コ ン silicon oxide film on the BPSG base substrate and S
A film was formed on an iN base substrate. The shape abnormality of the acid-generating chemically amplified resist was improved on the silicon oxide film on the SiN base substrate, but was hardly improved on the silicon oxide film on the BPSG base substrate. Furthermore, a film thickness of 100 °
Silicon oxide films on the BPSG base substrate and Si
A film was formed on an N base substrate. Vertical resist shapes could be obtained on the silicon oxide film on the BPSG undersubstrate and on the silicon oxide film on the SiN undersubstrate. In addition, Si
The results on the underlying substrate were the same as those on the SiN underlying substrate.

FIG. 4 shows the relationship between the thickness of the silicon oxide film on each base substrate and the amount of footing of the positive resist. FIG. 4 shows that the thickness of the silicon oxide film on the SiN base substrate is 10 °.
Above, more preferably 30 ° or more, the abnormal shape of the bottom of the positive resist can be improved. On the other hand, if the thickness of the silicon oxide film on the BPSG undersubstrate is not more than 50 °, more preferably not more than about 100 °, it indicates that the abnormal shape of the bottom of the positive resist cannot be improved. The conditions under which the abnormal shape of the skirt of the negative resist can be improved are substantially the same as the thickness of the silicon oxide film on each base substrate of the positive resist.

Further, the present inventor has found that the oxide of boron and the oxide of phosphorus existing on the BPSG base substrate trap the acid generated by exposure on the bottom surface of the resist, and the concentration of the acid at the bottom of the resist is reduced. We paid attention to the occurrence of abnormal shape at the bottom of the resist pattern.
Then, an attempt was made to remove these oxides before applying the resist and to remove them without damaging the BPSG base substrate. As a result, in the method of forming a resist pattern, after performing a sulfuric acid cleaning of a BPSG (silicon oxide film containing boron and phosphorus) base substrate, applying the resist, selectively exposing, and then performing a post-exposure bake. Do
Thereafter, by performing development, a vertical resist shape could be formed.

Further, as a result of aiming for a more reliable effect,
In the method for forming a resist pattern, after performing a sulfuric acid cleaning of the BPSG base substrate, a silicon oxide film having a film thickness of 50 ° or more, more preferably a film thickness of 100 ° or more is formed, and then the resist is applied and selected. A vertical resist shape could also be formed by performing post-exposure baking after the specific exposure, followed by development.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the method for forming a resist pattern according to the present invention will be described below with reference to the drawings.

<< First Embodiment >> (Reference Example) FIGS. 1A to 1E show a first embodiment.

As shown in FIG. 1B, a 50 Å thick film is formed on a BSPG (silicon oxide film containing boron and phosphorus) base substrate 10.
The silicon oxide film 11 having a film thickness of 100 ° or more, more preferably 100 ° or more is formed by CVD (Chemical Vapor).
It is formed using a deposition apparatus or an oxidation furnace. At this time, SOG (Spin On Glass)
s) The silicon oxide film formed by the method has a poor film quality and the effect of the present invention cannot be sufficiently obtained.
1 Vapor Deposition) device or an oxidation furnace.

Next, as shown in FIG. 1C, a positive-type acid-generating chemically amplified resist 12 (APEX-E; manufactured by Shipley Far East Co.) is applied to a thickness of about 0.75 μm, and is applied on a hot plate. Pre-exposure bake was performed at 100 ° C. for 60 seconds. Subsequently, by using a chromium mask (not shown), an exposure amount 20 mJ / cm ² by the exposure light (wavelength 248 nm) having a light intensity profile shown in FIG. 1A
Then, as shown in FIG. 1D, the exposed portions 12A are selectively formed. Thereafter, a post-exposure bake (PE
B) and a developing solution (MF-319; manufactured by Shipley Far East Co., Ltd.)
As shown in E, the solubilized portion 12a was dissolved and further rinsed (washed with water) to complete the formation of the vertical resist pattern 12 without tailing.

<< Second Embodiment >> (Reference Example) FIGS. 2A to 2E show a second embodiment.

As shown in FIG. 2B, the BPSG (silicon oxide film containing boron and phosphorus) base substrate 20 is washed with sulfuric acid. Next, as shown in FIG. 2C, a negative-type acid-generating chemically amplified resist 21 (SAL601-ER7; manufactured by Shipley Far East Co., Ltd.) is applied to a thickness of about 0.70 μm, and heated to 100 ° C. on a hot plate. A 60 second pre-exposure bake was performed. Subsequently, using an X-ray mask (not shown), an exposure dose of 300 m was obtained using synchrotron radiation X-rays (peak wavelength 0.7 nm) having the light intensity profile shown in FIG. 2A.
In J / cm ² , as shown in FIG.
Form A. At this time, since the acid generated by the entire surface exposure is not captured by the substrate 20 as described above, the exposed portion 2
At 1A, the acid concentration near the bottom of the resist does not change.
By performing post-exposure bake (PEB) at 105 ° C. for 7 minutes and alkali development using a developer (MF-319; manufactured by Shipley Far East Co.), a resist pattern leaving an insolubilized portion 21a as shown in FIG. 2E. Was formed, followed by rinsing (washing with water) to complete formation of a vertical resist pattern without clogging of the skirt.

<< Third Embodiment >> FIGS. 3A to 3F show a third embodiment.

As shown in FIG. 3B, the surface of BSPG (silicon oxide film containing boron and phosphorus) substrate 30 is washed with sulfuric acid. Next, as shown in FIG.
More preferably, a silicon oxide film 3 having a thickness of 100 ° or more
Form one. At this time, SOG (Spin On Gl)
The silicon oxide film formed by the (ass) method has a poor film quality and the effect of the present invention cannot be sufficiently obtained.
(Cal Vapor Deposition) apparatus or an oxidation furnace.

Further, as shown in FIG. 3D, a positive-type acid-generating chemically amplified resist 32 (APEX-E; manufactured by Shipley Far East Co.) is applied to a thickness of about 0.75 μm, and 100 μm on a hot plate. Pre-exposure bake was performed at 60 ° C. for 60 seconds. Subsequently, using a chrome mask (not shown), exposure light having a light intensity profile shown in FIG. 3A (wavelength: 248 nm) and an exposure amount of 20 mJ / cm ^2.
Then, as shown in FIG. 3E, the exposed portions 32A are selectively formed. Thereafter, a post-exposure bake (PE
B) and a developing solution (MF-319; manufactured by Shipley Far East Co., Ltd.)
As shown in F, the solubilized portion 32a was dissolved and rinsed (washed with water) to complete the formation of the vertical resist pattern 32 without tailing.

In any of the above embodiments, phosphoric acid, boric acid, nitric acid or the like is used in place of sulfuric acid, and the same effect can be obtained.

In any of the above embodiments, as the acid-generating chemically amplified resist, any positive or negative chemically amplified resist that can be generally used in a photolithography process is used. be able to. Further, the exposure light is not particularly limited, and g
Line (436 nm), i-line (365 nm), excimer laser (KrF: 248 nm, ArF: 193 nm), electron beam, X-ray (10 ^-2 to several hundreds of degrees), or the like can be used.

[0028]

According to the present invention, a silicon oxide film having a thickness of 50 ° or more, more preferably 100 ° or more, is
Since it is formed on the PSG, a vertical pattern can be formed without being affected by the BPSG base substrate even if the oxide film chemically amplified resist is a positive type or a negative type. Therefore, it is possible to control the size of the fine resist pattern.

Furthermore, according to the present invention, the oxide of boron and the oxide of phosphorus on the BPSG base substrate are removed, so that the acid generated by the exposure is not captured on the bottom surface of the resist, and the chemical reaction is prevented. Even if the amplification type resist is a positive type or a negative type, a vertical pattern shape can be formed on the BPSG base substrate. Therefore, it is possible to control the size of the fine resist pattern.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a method for forming a resist pattern according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a method of forming a resist pattern according to a second embodiment of the present invention.

FIG. 3 is a view illustrating a method of forming a resist pattern according to a third embodiment of the present invention.

FIG. 4 is a graph showing the relationship between the thickness of a silicon oxide film on a SiN substrate and a BPSG substrate and the amount of footing of an acid-generating chemically amplified positive resist.

FIG. 5 is a diagram illustrating a method of forming a resist pattern when a positive-type acid-generating chemically amplified resist is used in the related art.

FIG. 6 is a diagram illustrating a method of forming a resist pattern when a negative-type acid-generating chemically amplified resist is used in the related art.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor: Shigeyasu Mori 22-22, Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-6-84774 (JP, A) JP-A-7 -92694 (JP, A) JP-A-7-245252 (JP, A)

Claims (3)

(57) [Claims] 1. A resist pattern of an acid-generating chemical amplification system
A BPSG substrate with sulfuric acid and phosphorus.
Perform acid cleaning using either acid, boric acid, or nitric acid.
After that, a silicon oxide film is formed on the BPSG base substrate.
Film, apply acid-generating chemically amplified resist, and selectively
After exposure, bake after exposure and then develop
To form a substantially vertical resist shape.
Method of forming a resist pattern. 2. The method according to claim 1, wherein said silicon oxide film has a thickness of 100 ° or less.
2. The resist pattern according to claim 1, wherein
How to make turns. 3. The method according to claim 1, wherein the silicon oxide film is formed using a CVD apparatus.
3. The method according to claim 1, wherein
3. The method for forming a resist pattern according to item 1.