JPH09120942A - Formation of microminiature pattern in semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of such a failure as foot-cutting, undercutting, etc., in the lower section of a resist pattern at the time of forming the pattern by preventing the contamination of the upper surface of a water with amine by oxidizing the surface. SOLUTION: In order to prevent the upper surface of a prepared water 31 from reacting with amine, a thin oxide film 32 is formed on the surface by oxidizing the surface. The oxidizing process is performed by putting the wafer 31 in a plasma reactor and generating oxygen plasma by injecting oxygen while a constant pressure and constant voltage are impressed. In addition, in order to improve the adhesion of a photoresist formed on the water 31 in a succeeding process, the wafer 31 is subjected to prime treatment. Then a positive photoresist 33 is applied to the surface of the oxide film 32 on the wafer 31 and the photoresist 33 is exposed to light 35 through an exposure mask 34. After exposure, a resist pattern 36 is formed on the film 32 by developing the exposed photoresist 33.

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 fine pattern of a semiconductor device, and more particularly, it is possible to adjust the line width of a pattern by preventing the occurrence of defects such as foot or undercut during pattern formation. The present invention relates to a method for forming a fine pattern of a semiconductor device, which is adapted to manufacture of a highly integrated device by making it easy.

[0002]

2. Description of the Related Art Generally, in the manufacture of semiconductor devices, the photoresist applied on the upper surface of a wafer during the photo etching process for forming a resist pattern on the upper surface of a semiconductor substrate is contaminated with amines (Amine) in the atmosphere. It is easy to be beaten.

Therefore, the resist on the lower side of the resist pattern is not completely etched and remains on both side surfaces of the resist pattern, or a foot phenomenon occurs, or the resist is formed on the bottom side of the lower part of the resist pattern. Undercut exposed by etching (unde
Since an rcut) phenomenon occurs, an accurate fine pattern cannot be formed.

From this point of view, the phenomenon that the amine causes the foot or the undercut in the lower layer of the resist pattern as described above will be described with reference to the accompanying drawings.

First, a conventional general chemically amplified resist (Chemically
The light reaction mechanism of the Amplified Resist) is as follows.

FIG. 1A shows a conventional general two-component positive chemically amplified resist (Two-Component Chemical).
It is a light reaction state diagram with respect to ly Amplified Resist).

FIG. 1B shows a conventional general three-component negative chemically amplified resist (Three-Component Negati).
FIG. 3 is a photoreaction state diagram for ve Chemically Amplified Resist).

First, as shown in FIG. 1A, a general positive chemical amplification type resist is a resin (resin) 1.
And Dissolution Inhibitor attached to Resin 1
tor) 2 and a photoacid generator (Photoacid G
enerator) composed of components.

Here, the resin 1 to which the dissolution inhibitor 2 is attached
Is not dissolved in basic solution (Alkali Solution),
The resin without the dissolution inhibitor 2 has the property of being dissolved in a basic solution.

Therefore, if the characteristic of such a difference in solubility is utilized, it becomes possible to form a pattern.

That is, the resist not exposed is not dissolved, but the exposed resist is dissolved because the dissolution inhibitor 2 is separated from the resin 1 by H ⁺ of the strong acid (Strong Acid) emitted from the photo-acid generator 3. .

At this time, H ⁺ ions are generated by light energy and activated by heat energy to be dissolved in the inhibitor 2.
And plays a role of a catalyst for separating the resin 1.

The two-component positive chemically amplified resist is usually a resin containing polyhydroxystyrene (p
olyhydroxy styrene) is used, and the dissolution inhibitor is tertiary-butoxy carbony.
group) is used, and the photo-acid generator is tripenyl sulfonium triflate (Triphenyl Sulfornium Triflate)
Is used.

On the other hand, as shown in FIG. 1 (b), a conventional general negative chemical amplification type resist is composed of three components of a resin 1 and a photo-acid generator 3 or a cross-linking agent 4.

All of the three components and the like are dissolved in a basic solution, but if the resin 1 and the cross-linking agent 4 are bonded to each other by being exposed to light, they change into non-soluble substances and a difference in solubility occurs.
Pattern formation becomes possible.

That is, the unexposed resist is dissolved, but the exposed resist is combined with the resin 1 and the cross-linking agent 4 by the strong acid H ⁺ emitted from the photo-acid generator 3.
A difference in solubility occurs.

At this time, the H ⁺ ions play the role of a catalyst for causing the resin 1 and the cross-linking agent 4 to be bonded by being generated by light energy and activated by heat energy as in the case of FIG. 1A.

In the case of a three-component system negative chemical amplification type resist, polyvinylphenol (Poly vi
nyl phenol) and the cross-linking agent is melamine
Phenothiazine (Phenothiazin
e) is used.

Here, polyvinyl phenol is a substance which is well dissolved in a basic solution.

Particularly, when the two-component positive chemically amplified resist is exposed to light, the polyhydroxystyrene loses the tasialiboxy carbonyl group and is changed to polyvinyl phenol.

Such a chemically amplified resist is positive and negative in order to be patterned.
Strong acid H ⁺ must be generated regardless of the type of resist.

That is, in the case of a positive resist, only the areas where the resist is exposed and a strong acid exists are dissolved, and in the case of a negative resist, the resist is exposed and only the areas where a strong acid exists remains as a pattern.

Therefore, in any case, when the strong acid does not occur or disappears even if it does occur, in the case of the positive resist, the resist is not dissolved in the region where the strong acid has disappeared, and in the case of the negative resist. The resist will be dissolved in areas where the strong acid is gone.

The foot or undercut phenomenon will be described with reference to FIGS. 2 and 3.

2 (a) to 2 (c) show a first conventional example.
FIG. 6 is a process diagram of forming a resist pattern on a wafer using a positive chemically amplified photoresist in the embodiment of FIG.

First, as shown in FIG. 2A, a positive photoresist 12 is applied on the wafer 11.

Next, as shown in FIG. 2B, the positive photoresist 12 is irradiated with light 14 through the exposure mask 13 to be exposed.

Next, as shown in FIG. 2, the exposed positive photoresist 12 is developed to develop the wafer 1
A resist pattern 15 is formed on the surface 1.

At this time, a foot 16 is formed on the lower side surface of the resist pattern 15.

That is, the foot 16 is formed by contaminating the positive photoresist 12 with an amine (not shown).

3A to 3C are process diagrams of forming a resist pattern on a wafer using a negative chemically amplified photoresist in the second conventional example.

First, as shown in FIG. 3A, a negative photoresist 22 is applied on the wafer 21.

Next, as shown in FIG. 3B, the negative photoresist 22 is irradiated with light 24 through the exposure mask 23 to be exposed.

Next, as shown in FIG. 3C, the exposed negative photoresist 22 is developed to form a resist pattern 25 on the wafer 21.

At this time, an undercut 26 is formed on the lower side surface of the resist pattern 25.

That is, the undercut 26 is negative
The photoresist 22 is formed by being contaminated with an amine (not shown).

The phenomenon which causes the defective pattern such as the foot 16 and the undercut 26 when the photoresists 12 and 22 are contaminated by the amine is as follows.

Generally, oxide films (Oxide), nitride films (Nitride), polysilicon films (Polysilicon), titanium nitride films (Titanium Nitride), and impurity injection films (Boro) are used as the types of films used in the manufacturing process of semiconductor devices.
There are various types such as n-phosphorous Silica Glass (BPSG).

Particularly, among these, the titanium nitride film and the impurity-implanted film are contaminated with amine in the atmosphere, so that the amine concentration becomes high on the film surface.

At this time, the amine is basic as a derivative of ammonia and reacts with a strong acid to be neutralized, so that the strong acid existing on the film surface is consumed.

Therefore, in the case of the positive resist, the strong acid is consumed at the lower side edges of the pattern and the resist remains undissolved. In the case of the negative resist, the strong acid is consumed and the resist is dissolved in the same manner as described above. .

That is, when the resist is contaminated with amine,
In the case of the positive resist, as shown in FIG. 3A, the foot 16 is formed in the lower portion of the pattern in a form in which the resist is not dissolved and remains.

In the case of a negative resist, as shown in FIG. 3B, an undercut 26 having a form in which the resist is dissolved is formed at the bottom of the pattern.

[0044]

As described above, in the conventional method for forming a fine pattern of a semiconductor device, when a resist pattern is formed, a defect such as a foot or an undercut occurs at the bottom of the pattern due to amine. However, since it becomes difficult to form an accurate fine pattern, the manufacturing yield of semiconductor devices is reduced.

Particularly, it is a highly integrated device, for example, 256M.
In the case of DRAM, the minimum line width is 0.25 μm, which is very small. Therefore, in order to obtain excellent semiconductor device characteristics,
The line width of the resist pattern must be adjusted to the range of 0.225 to 0.275 μm, which is 0.25 μm ± 10%, but it becomes impossible to meet the line width condition when foot or undercut occurs. .

Therefore, in the conventional method for forming a fine pattern of a semiconductor element, it is difficult to form an accurate fine pattern, and it is not suitable for high integration of the semiconductor element.

The present invention has been devised to solve the above-mentioned conventional problems, and prevents the occurrence of defects such as foot or undercut during pattern formation. It is an object of the present invention to provide a method for forming a fine pattern of a semiconductor device in which the line width of a pattern can be easily adjusted.

Another object of the present invention is to provide a method for forming a fine pattern of a semiconductor device, which can improve the yield of the manufacturing process of the semiconductor device.

Still another object of the present invention is to provide a method for forming a fine pattern of a semiconductor device suitable for manufacturing a highly integrated device.

[0050]

A method for forming a fine pattern of a semiconductor device according to the present invention for achieving the above object comprises:
A step of preparing a wafer, a step of oxidizing the upper surface of the wafer, a step of applying a photoresist on the oxidized wafer, a step of exposing and developing the photoresist to form a photosensitive film pattern, Its characteristic is that it is configured to include ,.

In addition, the method for forming a fine pattern of a semiconductor device according to the first aspect of the present invention includes a step of preparing a wafer, a step of plasma-treating an upper surface of the wafer to oxidize the wafer, and an oxidation-treated wafer. The prime (prim
e) a treatment step, a step of applying a photoresist on the prime-treated wafer, and a step of exposing and developing the photoresist to form a photosensitive film pattern. .

The method for forming a fine pattern of a semiconductor device according to the second aspect of the present invention comprises the steps of preparing a wafer, oxidizing the upper surface of the wafer with a strong acid, and oxidizing the wafer. Prime
It is characterized by including a processing step, a step of applying a photoresist on a primed wafer, and a step of exposing and developing the photoresist to form a photoresist pattern.

[0053]

DETAILED DESCRIPTION OF THE INVENTION The present invention will now be described in detail with reference to the accompanying drawings.

4A to 4D are process diagrams of forming a fine pattern of a semiconductor device according to the first embodiment of the present invention.

First, as shown in FIG. 4 (a), the wafer 31 is prepared so that it does not react with amine.
The upper surface of the wafer is oxidized to form a thin oxide film 32 on the wafer 31.
To form

At this time, the oxide film 32 is preferably formed to a thickness of about 1000 Å or less.

In the oxidation process of the wafer 31, first, the wafer 31 is put in a plasma reactor (not shown), oxygen is injected into the reactor by applying a constant pressure and a constant voltage, and oxygen plasma is generated. Do in the state.

Further, the generation of oxygen plasma is performed by selectively using pure oxygen gas, a mixed gas of oxygen and argon, or a mixed gas of oxygen and nitrogen with a pressure of about 10 to 100 mTorr and an electric power of about 10 to 1000 W. About 10 to 1000c
It is performed under the condition of the supply flow rate of m ³ / min.

At this time, in the oxidation process of the upper surface of the wafer 31, the lower side of the resist pattern formed in the subsequent process is prevented from being contaminated with amine so that the undercut or foot phenomenon as in the conventional case does not occur. To

On the other hand, instead of the method using oxygen plasma, the method for forming the oxide film on the upper surface of the wafer 31 is as follows.
A wafer is placed in a reaction chamber and subjected to chemical vapor deposition (CVD) under constant pressure and temperature conditions.
A method of oxidizing the upper surface of the wafer by Deposition) can be used.

Next, a prime process for improving the adhesion of the photoresist formed on the wafer 31 in the subsequent process is performed.

Next, as shown in FIG. 4B, a positive photoresist 33 is applied to the oxide film 32 on the wafer 31.

At this time, the positive photoresist 33
Alternatively, a negative photoresist can be used.

Next, as shown in FIG. 4C, light 35 is investigated and exposed to the positive photoresist 33 through the exposure mask 34.

Next, as shown in FIG. 4D, the exposed positive photoresist 33 is developed to form a resist pattern 36 on the oxide film 32 on the wafer 31.

A second embodiment for preventing amine contamination according to the present invention will be described below with reference to FIGS. 5 (a) to 5 (d).

5A to 5D are process diagrams of forming a fine pattern of a semiconductor device according to the second embodiment of the present invention.

First, as shown in FIG. 5A, the wafer 41 is prepared so that it does not react with amine.
The upper surface of the wafer is oxidized to form a thin oxide film 42 on the wafer 41.
To form

At this time, in the step of oxidizing the wafer 41, the amine contaminated on the upper surface of the wafer 41 is neutralized and removed using a strong acid to oxidize the upper surface of the wafer 41.

As the above-mentioned strong acid, sulfuric acid (Sulfur
ic), phosphoric acid (Phosphoric Acid) or nitric acid, hydrochloric acid, etc. are selectively used.

Next, a prime process is performed to improve the adhesion of the photoresist formed on the wafer 41 in a subsequent process.

Next, as shown in FIG. 5B, a negative photoresist 43 is applied to the oxide film 42 on the wafer 41.

At this time, the negative photoresist 4
Instead of 3, a positive photoresist can be used.

Next, as shown in FIG. 5C, the negative photoresist 43 is irradiated with light 45 through the exposure mask 44 to be exposed.

Next, as shown in FIG. 5D, the exposed negative photoresist 43 is developed to form a resist pattern 46 on the oxide film 42 on the wafer 41.

[0076]

As described above, the method for forming a fine pattern of a semiconductor device according to the present invention has the following effects.

In the method for forming a fine pattern of a semiconductor device according to the present invention, the upper surface of the wafer is oxidized during pattern formation to prevent amine contamination, so that the lower surface of the resist pattern due to amine contamination is prevented. It is possible to prevent the occurrence of defects such as foot or undercut.

Further, in the method for forming a fine pattern of a semiconductor device according to the present invention, since a foot or an undercut phenomenon does not occur during pattern formation, an accurate pattern can be formed, so that the line width of a resist pattern can be easily adjusted. is there.

In the method for forming a fine pattern of a semiconductor device according to the present invention, since the line width of the resist pattern can be easily adjusted as described above, the manufacturing yield of the semiconductor device can be increased.

Therefore, the method for forming a fine pattern of a semiconductor device according to the present invention is suitable for manufacturing a highly integrated device requiring a fine pattern.

[Brief description of the drawings]

FIG. 1 (a) is a photoreaction state diagram for a conventional general two-component positive chemically amplified resist,
FIG. 1B is a photoreaction state diagram for a conventional general three-component system negative chemically amplified resist.

FIGS. 2A to 2C are fine pattern formation diagrams of a conventional semiconductor device using the positive resist according to the first conventional embodiment.

FIGS. 3A to 3C are fine pattern formation diagrams of a semiconductor device using a negative resist according to a conventional second embodiment.

4A to 4D are fine pattern formation diagrams of the semiconductor device according to the first embodiment of the present invention.

FIGS. 5A to 5D are fine pattern formation diagrams of a semiconductor device according to a second embodiment of the present invention.

[Explanation of symbols]

31 ... Wafer, 32 ... Oxide film, 33 ... Photoresist, 34 ... Exposure mask, 35 ... Light, 36 ... Resist pattern.

Claims (20)

[Claims] 1. A step of preparing a wafer, a step of oxidizing an upper surface of the wafer, a step of applying a photoresist on the oxidized wafer, a step of exposing and developing the photoresist, A method for forming a fine pattern of a semiconductor device, comprising the step of forming a resist pattern. 2. The method for forming a fine pattern of a semiconductor device according to claim 1, wherein the oxidation treatment step is performed by oxygen plasma treatment. 3. The semiconductor device according to claim 2, wherein in the oxygen plasma treatment, a wafer is placed in a plasma reactor and the upper surface of the wafer is oxidized by oxygen plasma generated in the reactor. Fine pattern forming method. 4. The plasma generation is about 10-100 mT
The fine pattern of a semiconductor device according to claim 3, wherein the fine pattern is generated under the conditions of gas pressure in the reactor of orr, electric power of about 10 to 100 W, and supply flow rate of about 10 to 1000 cm ³ / min. Forming method. 5. The method for forming a fine pattern of a semiconductor device according to claim 4, wherein the gas at the time of generating the plasma contains pure oxygen gas. 6. The method for forming a fine pattern of a semiconductor device according to claim 4, wherein the gas at the time of plasma generation includes a mixed gas of oxygen gas and argon. 7. The method for forming a fine pattern of a semiconductor device according to claim 4, wherein the gas at the time of plasma generation contains a mixed gas of oxygen gas and nitrogen. 8. The method for forming a fine pattern of a semiconductor device according to claim 1, wherein the oxidation treatment step is performed by a chemical vapor deposition method (CVD). 9. The method for forming a fine pattern of a semiconductor device according to claim 1, wherein the oxidation treatment step is performed using a strong acid. 10. The method of claim 9, wherein the strong acid includes sulfuric acid, phosphoric acid, nitric acid and hydrochloric acid. 11. The thickness of the layer to be oxidized is about 10.
The method for forming a fine pattern of a semiconductor device according to claim 1, wherein the fine pattern is formed to a thickness of 00Å or less. 12. Prior to applying the photoresist,
The method of claim 1, further comprising priming the upper surface of the wafer. 13. A step of preparing a wafer, a step of plasma-treating an upper surface of the wafer to oxidize, a step of priming the oxidized wafer, a photo-process on the primed wafer. A method of forming a fine pattern of a semiconductor device, comprising: a step of applying a resist; and a step of exposing and developing the photoresist to form a photoresist pattern. 14. The semiconductor device according to claim 13, wherein in the oxygen plasma treatment, a wafer is placed in a plasma reactor and the upper surface of the wafer is oxidized by oxygen plasma generated in the reactor. Fine pattern forming method. 15. The plasma generation is about 10-100 m
15. The fine pattern of a semiconductor device according to claim 14, which is generated under the conditions of gas pressure in the reactor of Torr, power of about 10 to 100 W, and supply flow rate of about 10 to 1000 cm ³ / min. Forming method. 16. The method for forming a fine pattern of a semiconductor device according to claim 15, wherein pure oxygen gas is used as the gas for generating the plasma. 17. The method for forming a fine pattern of a semiconductor device according to claim 15, wherein a gas for generating the plasma is a mixed gas of oxygen gas and argon. 18. The method for forming a fine pattern of a semiconductor device according to claim 15, wherein a gas for generating the plasma is a mixed gas of oxygen gas and nitrogen. 19. A step of preparing a wafer, a step of oxidizing the upper surface of the wafer with a strong acid, a step of priming the oxidized wafer, a photo process on the primed wafer. A method for forming a fine pattern of a semiconductor device, comprising: a step of applying a resist; and a step of exposing and developing the photoresist to form a photoresist pattern. 20. The method of claim 19, wherein the strong acid includes sulfuric acid, phosphoric acid, nitric acid and hydrochloric acid.