JP2001147518A - Pellicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the crystallization of a phenol derivative contained in an organic material used in a pellicle on a mask. SOLUTION: The amount of a phenol derivative contained in an organic material exposed to the inner face of a mask structure obtained by attaching a pellicle to a photomask and having >=0.1% weight decrease by heating by a heat weight measuring method when heating is carried out at 50 deg.C for 4 hr is adjusted to 0.1-15 μg.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material used for a pellicle used to prevent foreign matter from adhering to a photomask or a reticle used in a lithography process of manufacturing a semiconductor and a liquid crystal.

[0002]

2. Description of the Related Art Conventionally, in the formation of fine circuit patterns in the production of semiconductors and liquid crystals, a photolithography technique of optically copying a substrate by using a circuit original drawing called a photomask or a reticle (hereinafter abbreviated as "mask 8") is used. It is performed by a manufacturing device such as a stepper used. The adhesion of foreign matter to the mask becomes a shadow at the time of circuit copying (exposure), and causes a serious abnormality in the circuit such as disconnection or bridge. As a solution to this problem, a dust-proof component called a so-called pellicle is mounted on a mask to prevent foreign matter adhesion and contamination.

The basic structure of a pellicle is, as shown schematically in FIG. 1, a frame (hereinafter abbreviated as “pellicle frame 2”) having a shape conforming to a mask, and a film extremely transparent to exposure (hereinafter “pellicle film 1”). ) Is bonded via an adhesive having a bonding property to the pellicle frame and the pellicle film (hereinafter abbreviated as “membrane adhesive 3”), and the pellicle of the pellicle frame is further fixed for the purpose of fixing the pellicle to the mask. An adhesive (hereinafter, referred to as “mask adhesive 4”) is provided on a surface facing the film adhesive surface. In addition, a coating film may be provided on the inner surface of the pellicle frame or the mask adhesive for the purpose of capturing foreign substances when foreign substances enter the pellicle and preventing the foreign substances adhering to the pellicle frame from falling off (hereinafter referred to as “the pellicle frame”). Pellicle inner surface coating material 5 "). Further, a vent hole 7 is provided in the pellicle frame to prevent deterioration of the film and the mask due to expansion and contraction of the pellicle film due to a change in air pressure after the pellicle is mounted on the mask, and a vent hole for preventing foreign matter from entering the inside of the pellicle frame. In some cases, a porous membrane (hereinafter abbreviated as “vent filter 6”) may be provided so as to cover 7.

Heretofore, many organic materials have been used for members used for the pellicle having the above structure. For example, for a pellicle film having an exposure wavelength up to i-line (365 nm), a transparent resin made of a cellulose derivative material is used for a main film layer. In addition, foamed resin-based adhesive material for the mask adhesive,
A resin such as an acrylic adhesive or a butyl rubber adhesive is used. Organic materials are also used for the air holes and the pellicle inner surface covering material. Organic materials include weather resistance (heat, light, oxygen, ozone,
Water, etc.), and in many cases, a stabilizer is added in consideration of the production conditions and use conditions. In particular, a phenolic derivative is added as an antioxidant for the purpose of preventing a processing process by heating or oxidative deterioration over time.

[0005]

According to the study of the present inventors, the phenol derivative substance contained in these organic materials is crystallized on a mask, and foreign matter which causes a problem in a circuit pattern is generated. I found that. In order to solve such a problem, the present invention limits the amount of the phenol derivative that causes crystallization after adding an inevitably necessary phenol derivative to the organic material used for the pellicle. Thus, an object of the present invention is to provide a pellicle that does not generate foreign matter on a mask after the pellicle is mounted.

[0006]

That is, the present invention is based on a thermogravimetric method when heated at 50 ° C. for 4 hours contained in an organic material exposed on the inner surface when a pellicle is mounted on a mask. A pellicle, wherein the amount of the phenol derivative having a heat loss of 0.1% or more is configured to be 15 μg to 0.1 μg, and the inside of the mask structure is substantially equal to or less than the foreign matter generation concentration. is there. Less than,
The present invention will be described in detail. In the mask structure shown in FIG. 1 in which the pellicle is mounted on the photomask (however, in this study, the pellicle 7 without the pellicle inner surface coating material 5, the vent 7 and the vent filter 6) was used. Table 1 shows the results of a study on the generation of foreign matter on a photomask when the contained mask adhesive was used.

[0007]

[Table 1]

A substance having a heating loss of 0.1% or more by thermogravimetry when heated at 50 ° C. for 4 hours has a relatively high volatility. Moving the mask caused problems on the mask surface. For example, in Table 1, 2,6-di-t-butylphenol (heating loss of 13.6%) generates crystals when it is contained in an amount of 50 μg or more. At 10 μg, no crystallization occurs.
In consideration of actual use, the amount is preferably 5 μg or less. For example, when 2,4-di-t-butylphenol (loss on heating: -6.3%) is contained in an amount of 1000 μg or more, crystals are generated. At 10 μg or less, no crystal generation occurs. However, for practical use, the substance is 2,6-
Considering that it has a chemical structure similar to that of di-t-butylphenol, the content is preferably 5 μg or less.

For example, 2,6-di-t-butyl-4-hydroxymethylphenol (heat loss of 0.3%) is contained in an amount of 200 μg or more under clean room conditions in which no reactive gas is substantially present in the environment. In some cases, crystals are generated. At 10 μg or less, no crystal generation occurs. It is preferably 15 μg or less. For example,
Regarding 2,6-di-t-butyl-4-methylphenol, under clean room conditions in which substantially no reactive gas is present in the environment, no foreign matter is generated even if it contains 1000 μg. However, when stored in an atmosphere of ammonia as a reactive gas that may be present in a clean room, crystals are generated when the content is 50 μg or more. At 10 μg or less, no crystal generation occurs.

3,5-di-t-butyl-4-hydroxybenzaldehyde having a heat loss of 0.1% or less,
5-di-t-butyl-4-hydroxybenzoic acid is 100
No foreign matter was generated even at a content of 0 μg. As described above, the difference in the upper limit of the concentration at which crystal generation does not occur depending on the individual substances is due to the fact that the reactions of crystal nucleus generation and crystal growth in the crystal generation mechanism are individually different, and the starting material, intermediate product, It is considered that the upper limit of the concentration is determined kinetically depending on the generated substance, the surface state of the substrate, the atmospheric conditions, the temperature, and the like.

A phenol derivative having a heating loss of 0.1% or more may be contained in a material even when not intentionally added. For example, even when a generally used phenol derivative having a relatively high molecular weight is used, decomposition occurs depending on the conditions of the processing process, and a substance having a high heat loss is generated by reducing the molecular weight. In addition, there are cases where components are mixed from components remaining in the processing apparatus. Therefore, when a phenol derivative is used as a stabilizer, 0.1 μg of a phenol derivative having a heat loss of 0.1% or more is contained. Here, in the photomask used in this study, as shown in FIG. 1, one surface of a quartz glass substrate is coated with chromium metal, and the outermost layer is coated with chromium oxide. In addition, although this study was conducted using a mask adhesive, the space inside the pellicle in the mask structure was almost a closed space, so even if it was included in organic materials other than the mask adhesive, its If the amount is equal to or more than a predetermined amount, the same phenomenon occurs.

In practicing the present invention, the heating loss is 0.1 mm.
That is, the composition is selected so that the concentration of the phenol derivative of 1% or more is equal to or less than the above amount. Further, in order to more positively remove the phenol derivative having a heating loss of 0.1% or more, the substance can be reduced by performing a heating treatment at 80 ° C. or more. However, if the temperature exceeds 200 ° C., the loss of the effect of the antioxidant and the deterioration of the organic material proceed very quickly, so the upper limit of the heat treatment needs to be 200 ° C. More preferably, the temperature is set to 120 ° C. or lower.
In addition, for the organic material in which the oxidative deterioration is a problem due to the heat treatment in the temperature range of 80 to 200 ° C., the problem is solved by simultaneously performing the nitrogen flow.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to Examples and the like, but the present invention is not limited to these Examples and the like.

EXAMPLE 1 In the mask structure shown in FIG. 1 (however, in this study, a pellicle without the pellicle inner surface coating material 5, the vent hole 7, and the vent filter 7 was used), 2,6-di-oxidant was used as an antioxidant. 1-t-butyl-4-methylphenol
A pellicle was prepared in which 0.5 g of the mask adhesive added with 5 μg was mounted on a pellicle frame. This pellicle was mounted on a photomask that had been washed with a sulfuric acid-based chemical solution in advance, and stored under two kinds of environments, an environment in which ammonia gas was present and an environment in which reactive gas was not substantially present. After three months, the generation of foreign matter was confirmed, and no foreign matter was detected.

[0014]

Example 2 In the same manner as in Example 1, a mask adhesive having a concentration of 2,6-di-t-butyl-4-methylphenol containing 50 μg in 0.5 g of the mask adhesive was prepared. Was subjected to heat treatment at 120 ° C. for 120 hours.
The concentration of 2,6-di-t-butyl-4-methylphenol was 10 μg in 0.5 g of the mask adhesive.
The pellicle prepared with this adhesive is mounted on a photomask that has been washed with a sulfuric acid-based chemical solution in advance, and an environment where ammonia gas is present and an environment where reactive gas is substantially absent are used.
Stored under different environments. After three months, the generation of foreign matter was confirmed, and no foreign matter was detected.

[0015]

Example 3 In the same manner as in Example 1, a mask adhesive having a concentration of 2,6-di-t-butyl-4-methylphenol containing 100 μg in 0.5 g of the mask adhesive was prepared. Was subjected to a heat treatment at 190 ° C. for 6 hours under a nitrogen flow. As a result, the concentration of 2,6-di-t-butyl-4-methylphenol was 10 μg in 0.5 g of the mask adhesive. The pellicle prepared with this adhesive was mounted on a photomask that had been washed with a sulfuric acid-based chemical solution in advance, and stored under two types of environments, an environment in which ammonia gas was present and an environment in which reactive gas was not substantially present. After three months, the generation of foreign matter was confirmed, and no foreign matter was detected.

[0016]

COMPARATIVE EXAMPLE 1 As shown in Table 1, in a mask structure using a mask adhesive having a concentration exceeding a predetermined concentration for each substance for a pellicle, foreign matter was generated on the mask.

[0017]

According to the present invention, a substance contained in an organic pellicle constituent material exposed on the inner surface of a mask structure equipped with a pellicle is measured by thermogravimetry when heated at 50 ° C. for 4 hours. By setting the amount of the phenol derivative having a heating loss of 0.1% or more by the method to 15 μg to 0.1 μg, the concentration of the phenol derivative inside the pellicle in the mask structure becomes equal to or less than the concentration required for crystallization. No foreign matter is generated on a mask made of a compound or quartz.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a mask structure.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 pellicle film 2 pellicle frame 3 film adhesive 4 mask adhesive 5 pellicle inner surface coating material 6 vent filter 7 vent

Continuation of the front page (72) Inventor Hideaki Imai 2-1, Samejima, Fuji-shi, Shizuoka Prefecture Asahi Kasei Industries Co., Ltd. F-term (reference) 2H095 BC33 BC34

Claims (6)

[Claims] 1. An organic pellicle constituent material exposed on the inner surface of a mask structure on which a pellicle is mounted, wherein the material is 50 ° C.
Phenol derivative having a heating loss of 0.1% or more by thermogravimetry when heated for 4 hours at
A pellicle comprising a constituent material containing 0.1 μg. 2. The phenol derivative is 2,6-di-t-butylphenol, and its content is 5 μg to 0.1 μm.
The pellicle according to claim 1, which is g. 3. The phenol derivative is 2,4-di-t-butylphenol, and its content is from 5 μg to 0.1 μm.
The pellicle according to claim 1, which is g. 4. The phenol derivative is 2,6-di-t-butyl-4-methylphenol having a content of 15
The pellicle according to claim 1, wherein the pellicle is in an amount of from 0.1 to 0.1 µg. 5. The method according to claim 1, wherein the pellicle constituent material is 80 to 20 in advance.
5. A heat treatment at 0 [deg.] C.
The method for producing a pellicle according to any one of the above. 6. The pellicle manufacturing method according to claim 5, wherein the heat treatment is performed under a nitrogen flow.