JP3277395B2 - Sublimable antireflection film, method of forming the same, and method of manufacturing semiconductor device using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel antireflection film, a method for forming the same, and a method for manufacturing a semiconductor device using the antireflection film. INDUSTRIAL APPLICABILITY The present invention can be suitably used, for example, when a semiconductor device is manufactured by performing various processes on a base on which a step is formed due to various electrodes, wirings, element isolation regions, and the like on a semiconductor substrate.

[0002]

2. Description of the Related Art Conventionally, connection holes called contact holes and via holes are formed in an insulating film on a base having a step in a semiconductor manufacturing process. FIG.
As shown in FIG. 1A, a gate insulating film 1 is formed on a substrate 10.
1, an element isolation region 12 and an electrode made of polysilicon.
For example, silicon oxide (PSG, BPSG, AsSG, etc.) containing impurities or a coating insulating film (S) is formed on the base 1 where the step 14 is formed due to the formation of the wiring 13 and the like.
In some cases, an insulating film 2 made of OG) is formed, and a plurality of connection holes are opened in the insulating film 2. In this case, generally, as shown in FIG. 7B, a resist film 4 is formed on the entire surface, and resist patterning is performed to form openings 15a and 15b having shapes corresponding to desired connection holes by a normal lithography technique. Normally, a plurality of connection holes are simultaneously formed by etching the insulating film 2 using the obtained resist pattern 4 as a mask.

When a plurality of connection holes are to be formed on the base 1 having the steps 14 by such a method, the step projections 14a in which the electrodes / wirings 13 are formed and the electrodes / electrodes 13a are formed.
The opening diameter of the resist pattern 4 may be different from that of the stepped concave portion 14b where the wiring 13 is not formed. For example, as shown in FIG.
Da> Db despite the fact that the opening diameter Da of the resist opening 15a on 4a and the opening diameter Db of the resist opening 15b on the stepped recess 14b are both patterned to have the same opening diameter. There is.

One of the causes is considered to be a difference in the thickness of the insulating film 2 formed, for example, by reflow on the base 1, a difference in the reflected light intensity of the exposure light due to a difference in the reflectivity of the base 1, This is a difference in standing wave effect due to interference. Also,
Another possible cause is irregular reflection of exposure light due to the step 14.

As a conventional technique for suppressing these causes of non-uniform resist patterning, an antireflection film made of, for example, Si ₃ N ₄ (refractive index n = 2) having a thickness of １ ／ of the wavelength of exposure light is used. Is formed on a resist 4 by LP-CVD or the like, and a resist pattern is formed thereon (for example, "Super LSI General Dictionary" published by Science Forum Co., Ltd.).

As an example, Japanese Patent Application Laid-Open No. 4-199850
As described in Japanese Patent Application Laid-Open Publication No. H11-207, a method of applying an organic antireflection film, for example, an ARL (Anti-Reflecting Layer) on the insulating film 2 and forming a resist pattern thereon is known. .

[0007]

However, in the above-mentioned anti-reflection method, an anti-reflection film made of, for example, a Si ₃ N ₄ film having a thickness of １ ／ of the wavelength of the exposure light is formed on the resist 4 by LP-LP. In the method of forming by the CVD method or the like, it is necessary to control the thickness of the antireflection film every time the wavelength of the exposure light is different,
It was difficult to control this film thickness. In addition, even if an antireflection film having a uniform thickness is formed on a resist having a step, a substantial film thickness corresponding to the light exposure length of exposure light fluctuates, resulting in a change in antireflection effect. Sometimes occurred.

Further, an organic antireflection film such as ARL
Is applied on the insulating film 2 and a resist pattern is formed thereon. In general, the phenomenon common to organic coating films is that the coating is thin at the step-shaped protrusion 14a and thick at the step-shaped recess. In some cases, the antireflection effect fluctuates. Further, after the formation of the connection holes, a step of removing the ARL is required separately from the separation of the resist pattern, which complicates the process.

The present invention has been made in order to solve such problems of the prior art, and is directed to a case where a plurality of connection holes are simultaneously formed in an insulating film on a base having a step. Another object of the present invention is to provide a method of manufacturing a semiconductor device capable of achieving a desired connection hole patterning of the resist pattern opening.

[0010]

In order to achieve the above-mentioned object, the invention of claims 1 to 3 of the present application is directed to a method of using a sulfur-based sublimable material such as sulfur (S) or polythiazyl (SN) x as an antireflection film. A sublimable anti-reflection film is used.

Further, the invention of claims 4 to 7 of the present application provides a method for forming a sublimable antireflection film, which comprises using a gas containing at least a gas capable of producing free sulfur under discharge ionization conditions, ie, plasma conditions. The substrate is formed while being controlled at room temperature or lower. Gases that can produce free sulfur under discharge ionization conditions include S ₂ F ₂ , SF ₂ ,
SF ₄ , S ₂ F ₁₀ , S ₃ Cl ₂ , S ₂ Cl ₂ , SCl ₂ , S ₃ B
This is a gas selected from r ₂ , S ₂ Br ₂ , SBr ₂ , and H ₂ S. A configuration in which N ₂ is further added to these gases may be adopted.

Further, the invention according to claims 8 and 9 of the present application relates to a method of manufacturing a semiconductor device using a sublimable antireflection film, wherein a plurality of connection holes are simultaneously opened in an insulating film on a stepped base. Discloses a method of manufacturing a semiconductor device including a step of forming a resist pattern for performing the method. That is, a sublimable antireflection film and a resist film are formed in this order on an insulating film on a base having a step, and then the resist film is patterned. Subsequently, the resist pattern is used as a mask to continuously etch the sublimable anti-reflection film and the insulating film, and after removing the unnecessary resist pattern, the sublimable anti-reflection film is removed by sublimation by heating under reduced pressure. Configuration.

[0013]

According to the first to third aspects of the present invention, a sulfur-based sublimable material such as sulfur (S) or polythiazyl (SN) x is used as an antireflection film. On the other hand, although it is opaque, there is no problem that the exposure light leaks to the insulating film side and the difference in the standing wave effect due to the light interference based on the difference in the thickness of the base reflectance.

Further, the invention of claims 4 to 7 of the present application provides a method for forming a sublimable antireflection film, which comprises using a gas containing at least a gas capable of producing free sulfur under discharge ionization conditions, ie, plasma conditions. The substrate to be formed is formed while controlling it to room temperature or lower. That is, since the antireflection film is formed from the gas phase, the thickness of the antireflection film becomes uniform, and the effect of the antireflection does not vary.

Further, according to the invention of claim 8 of the present application, a sublimable inorganic antireflection film made of sulfur or polythiazyl is formed on an insulating film on a stepped base, and a resist film is formed thereon. Therefore, it is possible to avoid a difference in reflected light intensity due to a difference in reflectance from a base having a step or a difference in standing wave effect due to light interference due to a difference in thickness of an insulating film during exposure. Therefore, a resist pattern for simultaneously opening a plurality of connection holes can be formed with a good shape.

Furthermore, the invention of claim 9 of the present application provides:
Using the resist pattern thus formed as a mask, the sublimable antireflection film and the insulating film are continuously etched, and after removing the unnecessary resist pattern, the sublimable insulating film is heated under reduced pressure. To remove sublimation. An antireflection film made of sulfur or polythiazyl is
After the resist is stripped, it can be easily sublimated and removed by heating under reduced pressure. There is no risk of contamination remaining after removal. Sublimation of sulfur under reduced pressure is performed by TDS [Thermal Deso
According to the results of the rption spectroscopy analysis, a sharp peak is observed at 100 ° C.
C. or more, for example 120.degree. C., is sufficient. In the case of polythiazyl, sublimation under reduced pressure starts at 140 to 150 ° C., so that a substrate heating temperature of 150 ° C. is sufficient.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of a sublimable antireflection film according to the present invention, a method of forming the same, and a method of manufacturing a semiconductor device using the same will be described with reference to the drawings.

(Embodiment 1) This embodiment will be described with reference to process sectional views shown in FIGS.

First, as an example, a substrate 10 made of a semiconductor material such as silicon is thermally oxidized to form a gate oxide film 11 and an element isolation region 12, and an electrode / wiring 13 made of a material such as polysilicon is formed thereon. A base 1 having the step is prepared. For example, PSG, BPS
An insulating film 2 made of a low-melting glass material such as G or AsSG is formed. In this embodiment, these low-melting glass materials are formed as a reflow film to achieve flattening as shown in FIG. The reflow temperature is 1000 to 1000
It is 1050 ° C. and about 950 ° C. for AsSG. Up to this step, it can be formed by a known technique.

Next, a sublimable antireflection film 3 which is one of the features of the present invention is formed. In the present embodiment, a known magnetic field microwave plasma processing apparatus capable of controlling the substrate stage at room temperature or lower is used to deposit, for example, a 200 nm-thick sulfur on the insulating film 2 under the following film forming conditions. FIG.
The structure shown in FIG.

(Deposition condition of sublimable anti-reflection film 3) S ₂ F ₂ … 5 SCCM pressure… 1.3 Pa Microwave output 850 W RF bias… 0 W Substrate stage temperature… −70 ° C. Next, a resist film is applied and formed on the sublimable antireflection film 3, and a resist pattern having an opening 15 corresponding to a desired connection hole shape having a diameter of, for example, 0.35 μm is formed by a normal lithography technique. In this case, the difference in the reflected light intensity of the exposure light based on the stepped base 1, the difference in the standing wave effect due to light interference, the influence of irregular reflection, and the like are suppressed by the sublimable antireflection film 3, and as shown in FIG. , Resist opening 1
5 have the same diameter, for example, 0.35 microns.

Then, the substrate to be etched shown in FIG. 3 is subjected to a known reactive dry etching (RIE) apparatus capable of controlling the substrate stage temperature to room temperature or lower, using the resist pattern 4 as a mask, and a sublimable reaction preventing film 3 and an insulating film. 2 was continuously etched under the following conditions.

(Etching conditions) S ₂ F ₂ … 100 SCCM pressure… 1.3 Pa RF bias… 1.0 kW Substrate stage temperature… -70 ° C -8442
No. 7, filed as an invention, and is an etching method excellent in shape controllability and selectivity. Under these etching conditions, the sublimable antireflection film 3 at the bottom of the resist opening 15 is sputter-etched, and the insulating film 2 can be continuously etched. As shown in FIG. 4, a plurality of connection holes are simultaneously opened. You.

Next, as shown in FIG. 5, the resist pattern 4 is stripped with a resist stripper. Finally, the substrate is heated under reduced pressure to remove the sublimable anti-reflection film by sublimation to form a structure having a plurality of desired connection holes 16 having a diameter of, for example, 0.35 μm as shown in FIG. obtain.

(Embodiment 2) This embodiment is an example in which (SN) x (polythiazyl) is used as a sublimable antireflection film.

Although this embodiment will be described with reference to the process sectional views shown in FIGS. 1 to 6, the description up to FIG. 1, which is formed by a known technique, is the same as that of the first embodiment and will not be repeated.

Next, using a known magnetic field microwave plasma processing apparatus capable of controlling the substrate stage to room temperature or lower, (SN) x having a thickness of, for example, 200 nm under the following film forming conditions.
(Polythiazyl) was deposited as a sublimable antireflection film 3 on the insulating film 2 to obtain the structure shown in FIG.

(Deposition condition of sublimable antireflection film 3) S ₂ F ₂ … 5 SCCM N ₂ … 5 SCCM pressure 1.3 Pa Microwave output 850 W RF bias 0 W Substrate Stage temperature: -70 ° C. Next, a resist film is applied on the sublimable antireflection film 3 made of polythiazyl, and an opening 15 corresponding to a desired connection hole shape having a diameter of, for example, 0.35 μm is formed by a normal lithography technique. Is formed. In this case, the difference in the reflected light intensity of the exposure light based on the base 1 having the difference, the difference in the standing wave effect due to the light interference, the influence of the irregular reflection, and the like are suppressed by the antireflection film 3, and the resist opening All 15 have the same diameter.

Then, the substrate to be etched shown in FIG. 3 is subjected to a known reactive dry etching (RIE) apparatus capable of controlling the substrate stage temperature to room temperature or lower, using the resist pattern 4 as a mask, and the sublimable reaction preventing film 3 and the insulating film. 2 was continuously etched under the following conditions.

(Etching condition) S ₂ F ₂ … 100 SCCM pressure… 1.3 Pa RF bias… 1.0 kW Substrate stage temperature… −70 ° C. Sublimation at the bottom of resist opening 15 under the above etching conditions The reaction preventing film 3 is sputter-etched, so that the insulating film 2 can be continuously etched, and a plurality of connection holes are simultaneously opened as shown in FIG.

Under the present etching conditions, sulfur in the etching gas is combined with oxygen in the insulating film and removed in the form of SO and SO _{2 as} the insulating film is etched. Therefore, the contact hole etching is completed and the electrode / wiring 13
At the stage where the substrate 10 is exposed, the generation of SO and SO ₂ is sharply reduced. That is, in the emission spectrum, peaks around 316 nm and 327 nm based on SO or S
By monitoring the peak around 300 nm based on O ₂ , the end point of the etching can be detected.

Next, the resist pattern 4 is stripped with a resist stripper (FIG. 5). Finally, the substrate is heated to 150 ° C under reduced pressure.
Then, the sublimable anti-reflection film 3 is removed by sublimation to obtain a structure having a plurality of desired connection hole openings 16 having a diameter of, for example, 0.35 μm as shown in FIG. It is also possible to remove by heating under atmospheric pressure, but in this case, it is rapidly decomposed and removed at a heating temperature of about 208 ° C.

Although the present invention has been described based on the two embodiments, the present invention is not limited to these embodiments, and various steps can be made, and various materials and conditions can be changed. .

For example, in the above embodiment, the sublimable anti-reflection film is formed of sulfur or polythiazyl, but other sublimable materials which are not compatible with the solvent in the resist coating solution during resist spin coating may be considered.

In the above-described embodiment, a magnetic field microwave plasma processing apparatus was used as a method of forming the sublimable antireflection film. However, another apparatus that satisfies discharge ionization conditions, such as an RIE apparatus, can be used. In this case, the anode coupling method does not damage the insulating film.

In the above embodiment, S ₂ F ₂ is exemplified as a gas capable of producing free sulfur under discharge dissociation conditions.
Other halogenated sulfur gas having a large S / X ratio (X represents a halogen atom), for example, SF ₂ , SF ₄ , S ₂ F ₁₀ , S ₃
Cl ₂ , S ₂ Cl ₂ , SCl ₂ , S ₃ Br ₂ , S ₂ Br ₂ , SB
It is also possible to use a gas selected from r ₂ or H ₂ S gas alone or as a mixture. However, SF _{6, which} is a common sulfur fluoride gas, has a small S / X ratio and hardly produces free sulfur, which is not suitable for the purpose of the present invention. These S
An H-based gas such as H _{2 is} further added to a halogenated sulfur gas having a large / X ratio to capture halogen radicals X *, and further increasing the apparent S / X ratio is effective in generating free sulfur. It is.

In the above embodiment, the low-temperature etching technique for cooling the substrate to be processed to -70 ° C. is used for the etching after the formation of the resist opening. It is of course possible to adopt conditions.

Furthermore, the sublimation-reaction preventing film is removed by sublimation after the resist is removed after the completion of the etching. However, it is conceivable that the sublimation-removal film is removed immediately after the completion of etching without removing the resist. That is, if the sublimable reaction preventing film is sublimated and removed while the resist is present, the resist is lifted off. At this time, there is a concern that the removed resist adheres to the substrate to be processed and particles are contaminated. In this case, wet cleaning may be performed by known megasonic cleaning, jet flow cleaning, brush cleaning (scrub cleaning), or the like.

[0039]

According to the present invention, when a plurality of connection holes are simultaneously opened in an insulating film on a base having a step, sulfur,
By using a sublimable anti-reflection coating such as polythiazyl, the difference in the thickness of the insulating film, the difference in the reflected light intensity of the exposure light due to the difference in the reflectance of the base, the difference in the standing wave effect due to light interference, and the step difference The unevenness of the resist opening diameter due to the irregular reflection of the exposure light due to the above can be avoided.

Since the sublimable anti-reflection film is vapor-phase deposited from a gas capable of producing free sulfur under discharge dissociation conditions and a gas obtained by adding nitrogen thereto, it is formed conformally and has a thickness such as that of a conventional ARL. Because there is no unevenness,
There is no change in the anti-reflection effect.

After the etching, the sublimable antireflection film can be easily removed by heating under reduced pressure, and after the removal, it is a clean process that does not leave impurities serving as a contamination source.

[Brief description of the drawings]

FIG. 1 is a process cross-sectional view illustrating an embodiment of the present invention.

FIG. 2 is a process sectional view illustrating an example of the present invention.

FIG. 3 is a process cross-sectional view illustrating an example of the present invention.

FIG. 4 is a process cross-sectional view illustrating an example of the present invention.

FIG. 5 is a process cross-sectional view illustrating an example of the present invention.

FIG. 6 is a process cross-sectional view illustrating an example of the present invention.

FIGS. 7A and 7B are process cross-sectional views showing a conventional process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Underground 2 ... Insulating film 3 ... Sublimation anti-reflection film 4 ... Resist pattern 10 ... Substrate 11 ... Gate oxide film 12 ... Element isolation region 13 ... Electrode / wiring 14 ... Step 14a ... Step projection 14b ... Step depression 15 ... Resist opening 16: Connection hole

Claims (9)

(57) [Claims] 1. An anti-reflection film formed under a resist film for use in a step of patterning a resist film, wherein the anti-reflection film is made of a sulfur-based sublimable material. Anti-reflection film. 2. The method according to claim 1, wherein said antireflection film is made of sulfur.
The sublimable antireflection film according to the above. 3. The sublimable antireflection film according to claim 1, wherein said antireflection film is made of polythiazyl. 4. A method for forming an anti-reflection film formed under a resist film for use in a step of patterning a resist film, wherein the anti-reflection film can generate free sulfur under discharge ionization conditions. A method for forming a sublimable anti-reflection film, comprising forming a substrate to be formed with a gas containing at least a gas while controlling the temperature at room temperature or lower. 5. The gas capable of producing free sulfur under the discharge ionization conditions is S ₂ F ₂ , SF ₂ , SF ₄ , S ₂ F ₁₀ , S ₃
Cl ₂ , S ₂ Cl ₂ , SCl ₂ , S ₃ Br ₂ , S ₂ Br ₂ , SB
r _2, H ₂ formation method of sublimation antireflection film according to claim 4, wherein a gas selected from S. 6. A method for forming an antireflection film formed under a resist film for use in a step of patterning a resist film, wherein the antireflection film can generate free sulfur under discharge ionization conditions. A method for forming a sublimable antireflection film, comprising forming a substrate to be formed with a gas containing at least a gas and nitrogen while controlling the temperature to room temperature or lower. 7. The gas capable of producing free sulfur under the discharge ionization conditions is S ₂ F ₂ , SF ₂ , SF ₄ , S ₂ F ₁₀ , S ₃
Cl ₂ , S ₂ Cl ₂ , SCl ₂ , S ₃ Br ₂ , S ₂ Br ₂ , SB
r _2, H ₂ formation method of sublimation antireflection film according to claim 6, wherein a gas selected from S. 8. A method for manufacturing a semiconductor device, comprising a step of forming a resist pattern for simultaneously opening a plurality of connection holes in an insulating film on a base having a step, wherein a sublimable inorganic antireflection is formed on the insulating film. A method for manufacturing a semiconductor device, comprising sequentially forming a film and a resist film, and thereafter patterning the resist film. 9. A method for manufacturing a semiconductor device, comprising a step of forming a resist pattern for simultaneously opening a plurality of connection holes in an insulating film on a base having a step, wherein the base having the step is controlled to room temperature or lower. Forming a sublimable anti-reflection film on the insulating film, forming a resist film on the sublimable anti-reflection film, and patterning the resist film to correspond to a plurality of connection holes. Forming a resist pattern having an opening of the following; a step of continuously etching the sublimable antireflection film and the insulating film using the resist pattern as a mask to simultaneously open a plurality of connection holes; removing the resist pattern And heating the base having the steps under reduced pressure,
Sublimating and removing the sublimable anti-reflection film.