JP2001305719A - Pellicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pellicle which is high in light transmittance and is excellent in light resistance even when an F2 is used for an exposure light source. SOLUTION: This pellicle is formed by using a plate of synthetic quartz glass of <=20 ppm in the content of an OH group as a pellicle film. Preferably the thickness of the pellicle film is 1 to 500 μ, the variation in the thickness of the pellicle film is <=0.5 μ and the variation in the OH group content within the surface of the synthetic quartz glass constituting the pellicle film is <=10 ppm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pellicle used for protecting a semiconductor mask from dust when performing photolithography using the semiconductor mask.

[0002]

2. Description of the Related Art LSI by photolithography process
In a semiconductor device manufacturing process for manufacturing a (highly integrated circuit), a pellicle is provided on one or both sides of a semiconductor mask to prevent foreign substances such as dust from adhering to a semiconductor mask and transferring the foreign matter onto a wafer. I have.

[0003] This pellicle is usually constructed such that a pellicle film (light-transmitting dust-proof film) is held at a proper distance from the surface of the semiconductor mask by a holding frame of aluminum or the like. Therefore, when the wiring pattern on the surface of the semiconductor mask is transferred onto the wafer, the imaging focal length differs between the surface of the semiconductor mask and the surface of the pellicle film, and even if foreign matter adheres to the pellicle film, the foreign matter remains on the wafer. Not transcribed. Therefore, if the semiconductor mask is covered with the pellicle, it is possible to prevent foreign substances from entering from outside and to improve the yield in manufacturing semiconductor devices.

The pellicle film used for the pellicle has a film strength,
Light resistance, light transmittance at the wavelength of the exposure light source, and the like are required. For example, conventional g-line (436 nm) and i-line (365)
As a pellicle film material for light such as nm), a cellulosic material such as nitrocellulose and cellulose propionate is mainly used.

On the other hand, in a semiconductor device manufacturing process,
In order to improve the degree of integration by miniaturizing the pattern, the wavelength of the exposure light source has been shortened. Specifically, at present, Kr
Writing using an F excimer laser (wavelength: 248 nm) as an exposure light source has been realized, an ArF excimer laser (wavelength: 193 nm) is being realized, and the use of ultraviolet light having a shorter wavelength has been studied. In particular, an F ₂ laser (wavelength: 157 nm) is considered to be the most prominent as such shorter wavelength ultraviolet light.

As a pellicle film material durable to these short-wavelength light sources, a fluorine-containing resin having relatively low absorption in a short-wavelength ultraviolet region is known.
YTOP, trade name, manufactured by Asahi Glass Co., Ltd.) and Teflon AF (trade name, manufactured by DuPont, USA).

[0007]

[SUMMARY OF THE INVENTION] However, the fluorine-containing resin, in the case of a KrF excimer laser or ArF excimer laser as an exposure light source, exhibit good optical transparency and light resistance, an F ₂ laser When an exposure light source is used, the light transmittance is not sufficient, and the light is easily decomposed (deteriorated by light) due to laser irradiation, and is not practical for a pellicle.

For this reason, a new pellicle which has high light transmittance at a wavelength of 157 nm, excellent light resistance and excellent film strength, and can be used even when the exposure light source is an F ₂ laser is desired. An object of the present invention is to provide a pellicle which is excellent in light transmittance, light resistance and film strength even when an F ₂ laser is used as an exposure light source.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and uses a synthetic quartz glass plate having an OH group content of 20 ppm or less as a pellicle film. A pellicle is provided.

[0010]

According to the pellicle of the present invention, a defect of a semiconductor device caused by light absorption of a pellicle film can be prevented, and a decrease in exposure efficiency can be suppressed. 157nm wavelength
In order to further increase the internal light transmittance of the OH group, the OH group content is preferably 10 ppm or less.

The thickness of the pellicle film is 1 to 500 μm.
It is preferred that When the thickness exceeds 500 μm, it tends to be difficult to ensure in-plane uniformity of the thickness. Conversely, when the thickness is less than 1 μm, processing becomes difficult,
The film strength may be reduced. More preferably, the thickness of the pellicle film is 10 to 300 μm.

Further, it is preferable that the thickness variation of the pellicle film is 0.5 μm or less. Here, "variation in thickness" refers to a difference between the maximum value and the minimum value of the thickness of the pellicle film. Pellicle film thickness variation is 0.5μm
When the value exceeds, the optical path changes due to refraction in the pellicle film, so that the position of the pattern transferred onto the wafer is shifted, and good photolithography may not be performed.

In the photolithography step, in order to obtain a good transfer pattern, it is preferable that the light transmittance of the pellicle film is 90% or more and the variation of the light transmittance of the entire pellicle film is suppressed to 1% or less. . Here, “variation in light transmittance” means a difference obtained by subtracting the minimum value of light transmittance from the maximum value of light transmittance.

In order to suppress the variation in the light transmittance at a wavelength of 157 nm to 1% or less, the variation in the in-plane OH group content of the synthetic quartz glass constituting the pellicle film is reduced by 10 p.
pm or less. Here, “variation in OH group content” refers to the difference between the maximum value and the minimum value of the OH group content. More preferably, this variation is 5 ppm
Keep below.

The pellicle of the present invention can be used as it is, or a known inorganic or organic antireflection film can be provided on one or both surfaces of the pellicle film. The material of this antireflection film is Ca
Examples thereof include fluorides such as F ₂ , MgF ₂ and LiF.

The pellicle of the present invention is used by extending the pellicle film on one side of a pellicle frame and mounting the other side on a semiconductor mask. Attachment to the semiconductor mask, by applying adhesive or double-sided tape, etc.
Can do it.

The pellicle frame may be made of metal such as aluminum, aluminum alloy, stainless steel or the like, or made of synthetic resin or ceramic, but is not limited thereto. In addition, an adhesive, a pressure-sensitive adhesive, or the like can be used to stretch the pellicle film on the pellicle frame.

In order to prevent dust generation inside the pellicle,
An adhesive substance layer may be formed on the inner surface of the pellicle. That is, when the adhesive layer is provided inside the pellicle frame or the pellicle film, it is possible to prevent the generation of dust from the inside of the pellicle and to fix the floating dust to prevent the dust from adhering to the semiconductor mask.

When a semiconductor device is manufactured using the pellicle of the present invention, the pellicle of the present invention is mounted on a semiconductor mask having a circuit pattern formed on a glass plate surface with a vapor-deposited film of chromium or the like, and a resist is applied. on a silicon wafer, using a F ₂ laser light source, by transferring by exposing the circuit pattern, to produce the LSI.

According to the present invention, even when the F ₂ laser is used as an exposure light source, the pellicle is less deteriorated in light and has a good light transmittance. As a result, the pellicle is sharpened and finer by photolithography. Pattern can be stably formed on the wafer.

[0021]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

By a known soot method, SiCl ₄ is hydrolyzed in an oxyhydrogen flame, and the formed SiO ₂ fine particles are deposited on a substrate to produce a porous quartz glass body having a diameter of 400 mm and a length of 600 mm. . The porous quartz glass body was placed in an electric furnace capable of controlling the atmosphere, the temperature was raised under a reduced pressure of 150 Pa or less, the temperature was kept at 1000 to 1300 ° C. for a predetermined time, and then the temperature was raised to 1450 ° C. Hold the transparent quartz glass body (diameter 200 mm, length 45
0 mm).

This transparent quartz glass body is 120 mm × 14
Processed into a synthetic quartz glass plate of 0 mm x 0.5 mm thickness,
An antireflection film of MgF ₂ was applied.

The method for manufacturing the antireflection film is as follows. For example, when using an electron beam evaporation apparatus, after setting the substrate and the MgF ₂ evaporation material in a vacuum vessel, the vacuum vessel is evacuated to 1 × 10 ⁻³ Pa or less to form an optical or quartz vibration type film. While monitoring the film thickness with the rate monitor,
An anti-reflection film is laminated.

At this time, it is preferable to heat the substrate to about 300 to 400 ° C. in order to improve the durability of the antireflection film and the optical characteristics. When an antireflection film is deposited on both the front and back surfaces of the substrate, the film is formed one by one by turning the substrate upside down.

In the present example, the film thickness, the light transmittance at a wavelength of 157 nm, and the OH group content were measured by the following methods. (1) Film thickness: Measured with a thickness measuring device (laser focus displacement meter manufactured by KEYENCE CORPORATION) using laser light. (2) Light transmittance at a wavelength of 157 nm: measured using a vacuum ultraviolet spectrophotometer (VTMS-502 manufactured by Acton Research). (3) OH group content: measured by an infrared spectrophotometer, and determined from an absorption peak at a wavelength of 2.7 μm (J.
P. Williams et al. , Ceramic
Bull. , 55 (5), 524, 1976).

Table 1 shows the relationship between the in-plane maximum film thickness and its variation, the in-plane maximum OH group content and its variation, and the in-plane light transmittance and its variation. Examples 1 to 5, 8 and 9 are Examples, and Examples 6 and 7 are Comparative Examples.

The meaning of each item in Table 1 is as follows. (1) Maximum film thickness: The maximum value among the film thicknesses measured at 30 points in a grid pattern at intervals of 20 mm from the outer peripheral portion. (2) Variation in film thickness: The difference between the maximum value and the minimum value in the film thickness measured at 30 points in a grid at intervals of 20 mm from the periphery. (3) Maximum OH group content: The maximum value of the OH group content measured at 30 points in a grid at intervals of 20 mm from the outer periphery. (4) Variation in OH group content: The difference between the maximum value and the minimum value in the OH group content measured at 30 points in a grid at intervals of 20 mm from the outer peripheral portion. (5) Maximum value of light transmittance: The maximum value of the light transmittance at a wavelength of 157 nm measured at 30 points in a grid at intervals of 20 mm from the outer peripheral portion. (6) Light transmittance variation: The difference between the maximum value and the minimum value in the light transmittance at a wavelength of 157 nm measured at 30 points in a grid pattern at intervals of 20 mm from the outer peripheral portion.

[0029]

[Table 1]

The maximum value of the in-plane OH group content is 20 ppm
In the following cases, the in-plane light transmittance variation is reduced by 1
%. It can also be seen that if there is a variation in the film thickness in the plane, the variation in the light transmittance increases.

[0031]

The pellicle of the present invention has excellent transparency to F ₂ laser light, has small light deterioration, and has small variation in light transmittance. This has the effect that a stable pattern can be stably formed on a wafer for a long time by photolithography.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shinya Kikukawa 1150 Hazawa-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside (72) Inventor Junsuke Ikuta 1150 Hazawa-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Asahi Glass Co., Ltd. (72) Inventor Shigematsu Shigeto 1-2-1, Waki, Waki-machi, Kuga-gun, Yamaguchi Prefecture Inside Mitsui Chemicals Co., Ltd. (72) Inventor Hiroaki Nakagawa 1-2-1, Waki, Waki-cho, Kuga-gun, Yamaguchi Prefecture Mitsui Chemicals F term (reference) 2H095 BC33

Claims (4)

[Claims] 1. A pellicle characterized by using a synthetic quartz glass plate having an OH group content of 20 ppm or less as a pellicle film. 2. The pellicle according to claim 1, wherein the pellicle film has a thickness of 1 to 500 μm. 3. The pellicle film has a thickness variation of 0.5 μm.
The pellicle according to claim 1 or 2, wherein: 4. A synthetic quartz glass constituting a pellicle film,
4. The pellicle according to claim 1, wherein the OH group content in the plane has a variation of 10 ppm or less.