JPH0449628Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention aims to prevent foreign matter from adhering to transparent substrates (hereinafter referred to as masks) used in photomasks, reticle, etc. used in the lithography process of LSI manufacturing. Concerning the pellicle used. More specifically, the present invention relates to a pellicle that can be peeled off extremely easily if necessary after being attached to a mask. The present invention also relates to a type of pellicle that is reusable and can be replaced if necessary.

[Prior Art] When forming fine circuit patterns on a wafer in semiconductor manufacturing, semiconductor manufacturing equipment such as a stepper is used. What is important here is the quality of the mask for forming the circuit pattern incorporated into the semiconductor manufacturing equipment. In recent years, with the development of large-scale integrated circuits, the line width has become extremely fine, and this trend is expected to continue in the future. Therefore, the quality of the mask has a large impact on the operating rate and manufacturing cost of semiconductor manufacturing equipment. It's becoming commonplace.
It is particularly important that foreign matter adhering to the mask reduces the yield. One way to solve this problem is to attach a so-called pellicle to protect the mask from foreign objects (for example,
(See Special Publication No. 54-28716). On the other hand, large-scale integrated circuits are becoming more customizable and the trend toward high-mix, low-volume production is becoming stronger, which means using a large number of masks, and increasing the need for mask storage management. In this case, it is becoming recognized that storage with a pellicle attached is convenient for management.

FIG. 3 is an explanatory diagram of a pellicle used in such a place. Here, the optical thin film body 1 is attached to the support frame 2.
The adhesive layer 3 is firmly attached to the substrate without wrinkles or sagging. The support frame 2 has a double-sided adhesive tape 4 on the other end surface, and a protective film 5 is placed on top of the double-sided adhesive tape 4. Such a pellicle is used by peeling off the protective film 5 and attaching it to a mask via the adhesive layer of double-sided adhesive tape.

By the way, if the optical thin film body 1 is damaged or torn during installation or work after installation, or if foreign matter is found on the mask surface, or foreign matter that cannot be removed by blowing (spraying gas) etc. If the pellicle is found on the body, it must be replaced with a new pellicle. At that time, of course, the pellicle must be peeled off from the mask. This peeling is done by a fairly rough operation, which involves first breaking the optical thin film, holding the support frame with pliers, etc., and then inserting a screwdriver or the like between the mask surface and the adhesive layer surface of the double-sided adhesive tape and prying it open with strong force. It is being said.

Several proposals have been made so far as improvement measures. For example, JP-A-61-169848 discloses a method in which an opening is provided in a part of the support frame and a special jig is inserted into the opening to perform peeling. Although this method reduces the chance of scratching the mask, it leaves sticky residue from the double-sided adhesive tape on the mask surface, which requires time and effort to remove. Of course, the pellicle itself cannot be reused. Furthermore, Japanese Patent Laid-Open No. 60-147737 proposes a structure in which the support frame itself can be separated into a mask side and a pellicle side.
Although this proposal makes it easier to replace the pellicle, the problem of peeling of the adhesive layer on the mask side remains. A similar proposal to change the structure of the support frame is also found in JP-A-61-193151. Furthermore, Japanese Patent Laid-Open No. 60-75835 proposes weakening the adhesive strength of the double-sided adhesive tape on the mask side. However, although peeling becomes slightly easier, it cannot be a fundamental improvement. Furthermore, if the adhesive force is weakened too much, the risk of the pellicle falling from the mask during work increases.

[Problems to be solved by the invention] The method for peeling off the pellicle from the mask as described above not only has the problem of damaging the expensive pellicle, but also has the problem that the optical thin film body and the pellicle are not formed during the above operation. There was also the problem that metal powder and resin debris were generated from the materials used, and these adhered to the mask, making it difficult to clean the mask for reuse. Furthermore, there was also the problem that uncorrectable defects were caused in the pattern portion of the mask during the above operation. Furthermore, changes to the structure of the support frame as exemplified above cannot provide a drastic improvement in the problem of peeling of the pellicle from the mask.

The present invention was developed in view of the above-mentioned circumstances, and aims to provide a pellicle that can be easily and safely peeled off from a mask when necessary, and that can be reused after being peeled off.

[Means for solving the problems] As mentioned above, the double-sided adhesive tape for pellicle requires strong adhesive force when adhering to a mask, but requires extremely weak adhesive force when peeling off. These contradictory functions are required for the adhesive properties of the double-sided pressure-sensitive adhesive tape.

The inventors of the present invention have completed the present invention as a result of intensive investigation into whether these contradictory required performances can be achieved by changing the structure of the double-sided adhesive tape. That is, the present invention includes an optical thin film body,
In a pellicle comprising a support frame having a double-sided adhesive tape on one side and a double-sided adhesive tape on the opposite end surface, the double-sided adhesive tape has a base material of a double-sided adhesive tape with high elasticity, This is an easily peelable pellicle in which the base material is made by alternately laminating at least two double-sided adhesive tapes with low elasticity. It is surprising that peeling becomes extremely easy by constructing the double-sided adhesive tape as a laminated structure of different types of base materials.

The present invention will be explained below with reference to the drawings.

FIG. 2 is a sectional view of a conventional support frame and double-sided adhesive tape. Reference numeral 4a denotes an adhesive layer, which is made of, for example, acrylic, rubber, vinyl, epoxy, silicone, or the like adhesive. 4b is a double-sided adhesive tape base material, which is made of an elastic material such as butyl rubber or foamed polyurethane. FIG. 1 illustrates various aspects of the invention. That is, it has a laminated structure of double-sided adhesive tapes made of different base materials. In FIG. 1a, the base material 4b of the double-sided adhesive tape to be attached to the support frame side is made of a material with high elasticity, such as rubber or foam, and the base material 4d on the opposite side is made of a material with low elasticity, such as plastic. ing. In FIG. 1b, the structure is reversed from that in FIG. 1a. In FIG. 1c, the structure shown in FIG. 1a is further provided with a third double-sided adhesive tape, and in this case, the base material 4f of the third layer is made of a highly elastic material such as rubber or foam. be. Furthermore, the multilayer structures shown in FIG. 1c and above can be easily inferred from these figures.

The key to the present invention is the combination of highly elastic and less elastic base materials as described above.
This allows it to be easily and safely peeled off from the mask.

Examples of the highly elastic material serving as one of the base materials include rubber or foam, such as butyl rubber, chloroprene rubber, foamed polyurethane, and foamed polyethylene. Examples of the other base material with low elasticity include plastics, specifically polyester, polyethylene, polypropylene, polyimide, vinyl chloride,
Examples include polymethyl methacrylate and polycarbonate.

Examples of the adhesive include acrylic, rubber, vinyl, epoxy, and silicone adhesives.

Now, when using the double-sided adhesive tape with the structure of the present invention, when it becomes necessary to peel it off after adhering to the mask, a knife or the like can be placed on different parts of the base material, for example, near the interface between 4a and 4c in Figure 1a. can be inserted with a width of several centimeters. If you then lift the support frame with less force, it will come off very easily.
First, the mask and pellicle can be separated. Next, the double-sided adhesive tape remaining on the mask can be peeled off very easily by inserting a small peg and grasping it with tweezers. At this time, almost no sticky substance remains. The peeling method using such an operation eliminates the risk of damaging the mask. Generally, when two objects are bonded together using double-sided adhesive tape, the resistance to peeling is extremely high against forces in the vertical direction, but very little against forces in the parallel direction. The present invention skillfully uses this principle.

The pellicle after peeling can be reused when the double-sided adhesive tape has a multilayer structure as shown in FIG. 1c. Of course, since it uses an elastic base material, it can be easily attached to a mask.

Generally, the thickness of double-sided adhesive tape is about 0.1 mm to 2.0 mm, but it is considerably thicker at about 1.0 mm to prevent mistakes when attaching it to the mask. In order to prevent the mask from falling during work after being worn, the adhesive force of the adhesive layer is quite strong, ranging from 100 to 1000 g/cm (adhesive force values are based on the JIS Z-0237 adhesive force test method).

As the optical thin film body, a single layer body or a body having an antireflection layer can be used. Inorganic substances such as quartz and polymers can be used as the material for the film constituting the central layer. Polymers include polyethylene terephthalate, cellulose esters,
Examples include polycarbonate and polymethyl methacrylate. In particular, nitrocellulose and cellulose acetate are generally used as suitable materials. Materials for the anti-reflection layer include:
Inorganic substances such as MgF ₂ and polymers such as polystyrene and Teflon can be used.

Aluminum alloy, plastic, etc. can be used as the support frame. Its size is about 1 to 8 inches in diameter or 1 to 8 inches square, depending on the size of the mask, and its height is about 2 to 10 mm.
The pellicle is stored in a clean case to prevent rubber from adhering to it until it is ready for use. When used in a stepper, pellicles are often attached not only to the image side of the mask but also to other surfaces because the effects of foreign objects are extremely sensitive.

The present invention will be explained in more detail with reference to Examples below.

[Example] Example 1 First, a double-sided adhesive tape (Sumitomo 3M Co., Ltd. No. 4262). Next, the base material is polyester, the adhesive is acrylic, and the thickness is 0.13.
mm double-sided adhesive tape (Sumitomo 3M ST416P) was attached. Apply epoxy adhesive to the opposite side of such a support frame, and attach it to a separately prepared optical thin film (nitrocellulose center layer, anti-reflective fluoropolymer layers on both sides). It stuck. The pellicle made in this way was attached to a mask by applying pressure to the support frame so that the double-sided adhesive tape would sink by about 0.4 mm.

Thereafter, a knife was inserted across a width of about 3 cm between the two layers of base material at the corner of the support frame, and when the support frame was lifted, the mask and pellicle were easily separated. Next, I used a knife to peel off about 1 mm of the corner of the double-sided adhesive tape where the base material remaining on the mask was polyester, and when I picked up the peeled part with tweezers, I was able to peel off the tape cleanly. The detached pellicle could be reattached to the mask without any deformation. However, in this case of reuse, only one type of base material is used, so when it is further peeled off, it cannot be reused after that.

Example 2 A pellicle was made by reversing the positional relationship of the double-sided adhesive tape with the neoprene rubber base material and the double-sided adhesive tape with the polyester base material in Example 1, and was attached to a mask. In this case as well, the mask and pellicle could be separated easily and cleanly in the same way. The pellicle after this peeling could be peeled off in a state where it could be used again.

Examples 1 and 2 show that although there is a considerable difference in adhesive strength even with the same acrylic adhesive layer due to differences in base material and thickness, the laminate of the present invention It was confirmed that it could be easily peeled off in the same way.

Example 3 In Example 2, a double-sided adhesive tape having a polyester base material was further laminated. Such a pellicle was attached to a mask in the same manner as in Example 1. By inserting a knife between the base materials of the second and third layers of double-sided adhesive tape and peeling it off, the pellicle after peeling becomes the pellicle with the structure of Example 2, so this pellicle can be used at least three times. It turns out.

[Effects of the Invention] As explained above, according to the configuration of the present invention, it has become possible to provide a pellicle that can be easily peeled off from a mask and can solve many of the problems that have occurred during peeling. In addition, the peeled pellicle can be reused, and if necessary, it can also be reused by replacing the double-sided adhesive tape.

[Brief explanation of the drawing]

Figure 1 is a sectional view of the support frame and double-sided adhesive tape in a pellicle according to the present invention, Figure 2 is a sectional view of the support frame and double-sided adhesive tape used in a conventional pellicle, and Figure 3 is a general pellicle. An explanatory diagram of a pellicle, in which 1 is an optical thin film body, 2 is a support frame, 3 is an adhesive layer, 4 is a double-sided adhesive tape, 5 is a protective film, 4
a, 4c, 4e are adhesive layers of double-sided adhesive tape, 4
b, 4d, and 4f indicate the base materials of the double-sided adhesive tape.

Claims (1)

[Scope of utility model registration request] In a pellicle comprising an optical thin film body and a support frame having the optical thin film body on one side and having a double-sided adhesive tape on the opposite end surface, the double-sided adhesive tape has a base material with high elasticity. An easily peelable pellicle comprising at least two double-sided adhesive tapes and at least two double-sided adhesive tapes whose base materials have low elasticity laminated alternately.