JP2011076037A - Method for manufacturing pellicle and pellicle for lithography - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pellicle frame which minimizes deformation of an exposure original plate caused by deformation of the pellicle frame even when the pellicle is stuck to the exposure original plate, and to provide a pellicle for lithography, having the above pellicle frame. <P>SOLUTION: A method for manufacturing a pellicle frame is provided, including a step of heat treating a pellicle frame disposed on a flat face, while the pellicle frame under a load. By the method, a pellicle frame having a flatness of 15 μm or less is efficiently obtained. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lithography pellicle and a pellicle frame used as a dust mask for a lithography mask when a semiconductor device such as an LSI or a VLSI or a liquid crystal display panel is manufactured. In particular, the present invention relates to a method for manufacturing a pellicle frame used for the pellicle.

  In the manufacture of semiconductors such as LSI and VLSI, or the manufacture of liquid crystal display panels, a pattern is produced by irradiating light to a semiconductor wafer or a liquid crystal original plate. If dust is attached to the exposure original plate used in this case, Because this dust absorbs light or bends it, the transferred pattern will be deformed, the edges will be rough, the ground will be black, and the dimensions, quality, appearance, etc. There was a problem of being damaged. In the present invention, the “exposure master” is a general term for a lithography mask (also simply referred to as “mask”) and a reticle. Hereinafter, a mask will be described as an example.

  Although these operations are usually performed in a clean room, it is difficult to keep the exposure original plate clean even in this clean room, so a pellicle that allows exposure light for dust prevention to pass through the surface of the exposure original plate well is used. The method of pasting is taken.

  The basic configuration of the pellicle includes a pellicle frame and a pellicle film stretched on the pellicle frame. The pellicle film is made of nitrocellulose, cellulose acetate, a fluorine-based polymer or the like that transmits light (g-line, i-line, etc.) used for exposure well. A good solvent for the pellicle film is applied to the upper side of the pellicle frame, and the pellicle film is air-dried and bonded, or is bonded with an adhesive such as an acrylic resin, an epoxy resin, or a fluorine resin. Furthermore, in order to mount the exposure original plate on the lower side of the pellicle frame, an adhesive layer made of butene resin, vinyl acetate resin, acrylic resin, silicone resin, etc., and a reticle adhesive protective liner for the purpose of protecting the adhesive layer Is provided.

  The pellicle is placed so as to surround the pattern area formed on the surface of the exposure original plate. Since the pellicle is provided to prevent dust from adhering to the exposure original plate, the pattern region and the outside of the pellicle are isolated so that dust outside the pellicle does not adhere to the pattern surface.

  In recent years, LSI design rules have been miniaturized to sub-quarter microns, and accordingly, the wavelength of exposure light sources has been shortened, that is, g-rays (436 nm) using mercury lamps, which has been the mainstream until now. , I-line (365 nm) is shifting to KrF excimer laser (248 nm), ArF excimer laser (193 nm), and the like. As miniaturization progresses, the flatness required for masks and silicon wafers has become increasingly severe.

  After the mask is completed, the pellicle is affixed to the mask to prevent pattern dust. When the pellicle is attached to the mask, the flatness of the mask may change. When the flatness of the mask is deteriorated, as described above, there is a possibility that problems such as defocusing occur. Further, when the flatness changes, the shape of the pattern drawn on the mask changes, which causes a problem that the mask overlay accuracy becomes problematic.

  Although there are several factors that change the mask flatness due to the pellicle attachment, it has been found that the largest factor is the flatness of the pellicle frame.

  In recent years, the flatness required for a mask has gradually become stricter from the requirement of flatness of 2 μm on the pattern surface, and a demand of 0.5 μm or less, preferably 0.25 μm has emerged after the 65 nm node.

  In general, the flatness of the pellicle frame is about 20 to 80 μm. However, when a pellicle using a frame with such a poor flatness is attached to a mask, the shape of the frame is transferred to the mask and the mask is deformed. . The pellicle is pressed against the mask with a large force of about 200 to 400 N (20 to 40 kg weight) at the time of pasting. The flatness of the mask surface is flat compared to the pellicle frame. For this reason, when the pressing to the mask ends, the pellicle frame tries to return to its original shape and deforms the mask.

  When the mask is deformed, the flatness of the mask may be deteriorated. In this case, a defocus problem occurs in the exposure apparatus. On the other hand, the mask may be deformed and the flatness may be improved, but even in this case, the pattern formed on the mask surface is distorted, and as a result, the pattern image transferred to the wafer is distorted when exposed. To do. Since the distortion of the pattern also occurs when the flatness is deteriorated, there is a problem that the pattern image is always distorted when the mask is deformed by attaching the pellicle.

  In view of the above circumstances, the problem to be solved by the present invention is as follows. First, even if the pellicle is attached to the exposure original plate, the deformation of the exposure original plate due to the deformation of the pellicle frame can be reduced as much as possible. It is to provide a method for manufacturing a pellicle frame. Second, to provide a pellicle for lithography having such a pellicle frame.

  The inventors of the present invention can efficiently and inexpensively obtain a target pellicle frame by forming a frame shape and then heat-treating the pellicle frame placed on a flat surface under a load. I found out that I can do it.

That is, the said subject of this invention is achieved by the following means. These are listed together with (2) to (6) which are preferable practical aspects.
(1) A method for manufacturing a pellicle, comprising a step of heat-treating a pellicle frame placed on a flat surface under a load.
(2) The method for producing a pellicle according to (1), wherein the flatness of the flat surface is 5 μm or less.
(3) The method for producing a pellicle according to (1), wherein the temperature of the heat treatment is 140 to 250 ° C.
(4) The method for producing a pellicle according to (1), wherein the load is about 4.90 to about 196 N (0.5 to 20 kg weight).
(5) The method for producing a pellicle according to any one of (1) to (4), wherein a pellicle frame made of a material having a Young's modulus of 1 to 80 GPa is used.
(6) The method for producing a pellicle according to any one of (1) to (5), wherein a pellicle frame made of an aluminum alloy is used.
(7) The pellicle according to any one of (1) to (6), wherein a pellicle film is stretched on one end face of the pellicle frame via a pellicle film adhesive, and an exposure original plate adhesive is provided on the other end face A pellicle for lithography manufactured by a manufacturing method.

  According to the present invention, there is provided a pellicle for lithography in which a pellicle frame having a flatness of 15 μm or less can be efficiently obtained, and deformation of the exposure original plate caused by deformation of the pellicle frame can be reduced as much as possible. I was able to.

It is an example of a conceptual sectional view showing a configuration example of a pellicle. It is a figure which shows an example of sectional drawing at the time of pellicle frame heat processing.

Hereinafter, the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the pellicle for lithography according to the present invention has a pellicle film 1 stretched on the upper end surface of a pellicle frame 3 with an adhesive layer 2 for attaching a pellicle film. An adhesion adhesive layer 4 for adhering the pellicle to the exposure original plate (mask or reticle) 5 is usually formed on the lower end surface of the pellicle frame 3, and a liner (not shown) is provided on the lower end surface of the adhesion adhesive layer. Attached so as to be peelable. The pellicle frame may be provided with a not-shown pressure adjusting hole (vent), and a dust filter (not shown) may be provided at the vent for the purpose of particle removal.

A jig hole may be provided in the pellicle frame. The shape of the jig hole in the depth direction is not specified, and may be a recess having a taper at the tip of the cylinder as long as it does not penetrate.
As for the cross-sectional shape of the portion where the pressure adjusting hole is provided, the outer surface on which the pressure adjusting filter is attached is preferably a flat surface.

  The pellicle of the present invention is designed as appropriate according to the shape of the mask. Usually, the planar shape of the pellicle frame is a ring shape, a rectangular shape, or a square shape, and the circuit pattern portion provided on the mask is arranged as follows. It has the size and shape to cover. The corners of the rectangular (including square) pellicle frame may be rounded. The height of the pellicle frame is preferably about 1 to 10 mm, more preferably about 2 to 7 mm. The upper side and the lower side of the pellicle frame are preferably 1 to 5 mm, more preferably about 2 mm.

  As a material constituting the pellicle frame, a material having a Young's modulus of 1 to 80 GPa is preferable, and aluminum, a magnesium alloy, a synthetic resin, and the like can be preferably exemplified, and aluminum is more preferably used.

  As aluminum, conventionally used aluminum alloy materials can be used. Preferably, JIS A7075, JIS A6061, JIS A5052 material, etc. are used, and the cross-sectional shape described above is provided, and the strength as a pellicle frame is ensured. There is no particular limitation as long as possible. The surface of the pellicle frame is preferably roughened by sandblasting or chemical polishing before the coating is provided. In the present invention, a conventionally known method can be adopted as a method for roughening the surface of the frame. A method of roughening the surface by blasting the surface of the aluminum alloy material with stainless steel, carborundum, glass beads or the like and further chemically polishing with NaOH or the like is preferable.

  The pellicle frame of the present invention is a material having a Young's modulus of 1 to 50 GPa instead of using a material having a Young's modulus of around 69 GPa, such as JIS A7075, JIS A6061, and JIS A5052 which are conventionally used aluminum alloy materials. It is also preferable to comprise. Examples of the material having a Young's modulus within the above range include 44 GPa of magnesium alloy, 3 GPa of acrylic resin, and 2.5 GPa of polycarbonate resin.

  In the present invention, it is preferable that a chamfer is formed at the corner between the exposure original plate adhesion surface and / or pellicle film adhesion surface and the inner and outer surfaces of the pellicle frame on the exposure original plate adhesion surface and / or pellicle film adhesion surface of the pellicle frame.

  The average flatness of the pellicle frame is about 20 to 80 μm. In the present invention, it is preferable to use a pellicle frame having a flatness of 80 μm or less.

  When the pellicle frame has good flatness, the amount of deformation of the pellicle frame can be reduced when the pellicle is affixed to the mask. As a result, the deformation stress of the pellicle frame is reduced, and the deformation of the mask is kept small. Can do.

  The “flatness” of the above-mentioned pellicle frame means that the height is measured at a total of eight points, that is, four corners and four central points of the pellicle frame, a virtual plane is calculated, It was set as the value computed by the difference which pulled the lowest point from the highest point among the distance of each point.

  The flatness of the pellicle frame can be measured by a “laser displacement meter having an XY axis program stage”. In the present invention, a self-made displacement meter was used.

  In the present invention, the pellicle frame preferably has a black oxide film and / or a black polymer film in order to absorb stray light. When the pellicle frame is made of an aluminum alloy, an aluminum alloy pellicle frame having a black alumite film and / or a polymer electrodeposition coating film is particularly preferable.

  As a method of forming a black alumite film on the surface of the pellicle frame, generally, it is treated with an alkali treatment bath such as NaOH for several tens of seconds, then anodized in a dilute sulfuric acid aqueous solution, and then black dyed and sealed. A black oxide film can be provided on the surface.

  Moreover, although a polymer film (polymer coating) can be provided by various methods, generally spray coating, electrostatic coating, electrodeposition coating, etc. are mentioned, but it is preferable to provide a polymer film by electrodeposition coating.

  For electrodeposition coating, either thermosetting resin or ultraviolet curable resin can be used. Moreover, either anion electrodeposition coating or cationic electrodeposition coating can be used for each. In the present invention, since UV resistance is also required, anionic electrodeposition coating of a thermosetting resin is preferable from the viewpoint of coating stability, appearance, and strength.

  In the pellicle for lithography according to the present invention, a pellicle film is stretched on one end surface as an upper side via a pellicle film adhesive, and an exposure original plate adhesive is provided on the other end surface as a lower side. Can be manufactured.

  The type of pellicle film is not particularly limited, and for example, an amorphous fluoropolymer conventionally used for excimer laser is used. Examples of the amorphous fluoropolymer include Cytop (trade name, manufactured by Asahi Glass Co., Ltd.), Teflon (registered trademark) AF (trade name, manufactured by DuPont), and the like. These polymers may be used by dissolving in a solvent as necessary when preparing the pellicle film. For example, these polymers can be appropriately dissolved in a fluorine-based solvent.

Next, a method for manufacturing a pellicle frame according to the present invention will be described with reference to FIG.
As shown in FIG. 2, the pellicle frame 3 is mounted so that the mask bonding adhesive layer side of the pellicle frame 3 is in contact with the substrate 7 made of, for example, a quartz plate, and the pellicle frame 3 is bonded to the pellicle film bonding adhesive layer side. A load 9 is applied via the pressing plate 8. And the heat processing which is the characteristics of this invention is performed.

The flatness of the flat surface of the substrate 7 is preferably as flat as possible, but is practically preferably 5 μm or less.
In the heat treatment, the pellicle frame can be heated to a predetermined temperature, for example, an energization heating body can be wound around the pellicle frame, or infrared rays can be irradiated, and the entire system can be subjected to a required temperature atmosphere.

It is preferable that the temperature of heat processing is 140-250 degreeC.
When the temperature of the heat treatment of the pellicle frame is less than 140 ° C., the treatment takes a long time, and when the temperature exceeds 250 ° C., the surface of the frame may be cracked or discolored.

The pressing plate may be a conventionally used one as long as it can transmit the pressing force uniformly to the pellicle frame. An example is a quartz plate (thickness 6 mm ) having a mass of 0.3 kg .
The load applied to the pellicle frame may exceed about 196 N (20 kg weight), but the flatness improving effect is not so great. Further, even if there is no load, a certain effect can be obtained with only the press plate, but since it takes a long time for the treatment, about 4.90 to about 196 N (0.5 to 20 kg weight) is preferable in practice.
As the load, an appropriate material such as a lead plate, a weight, or a weight can be used.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited only to the following Example.

  A pellicle frame made of an aninium alloy and having an outer dimension of 149 mm × 122 mm × 3.5 mm and a width of 2 mm was produced. C corners were chamfered on the four corners of the pellicle frame.

Example 1
On the quartz plate having a flatness of 3 μm, the pellicle frame was placed so that the side to which the mask adhesive was applied was in contact, and a load was applied using a weight of 2 kg (FIG. 2). In this state, it was allowed to stand in an oven at 185 ° C. for 2 hours. The flatness of the mask adhesive application surface of this frame was measured.

(Example 2)
The flat pellicle frame was placed on a quartz plate having a flatness of 3 μm so that the side of the pellicle frame to which the mask adhesive was applied was in contact, and a load was applied using a weight of 2 kg. In this state, it was allowed to stand in an oven at 140 ° C. for 2 hours. The flatness of the mask adhesive application surface of this frame was measured.

(Example 3)
The flat pellicle frame was placed on a quartz plate having a flatness of 3 μm so that the side of the pellicle frame to which the mask adhesive was applied was in contact, and a load was applied using a weight of 2 kg. In this state, it was allowed to stand in an oven at 250 ° C. for 2 hours. The flatness of the mask adhesive application surface of this frame was measured.

Example 4
The pellicle frame was placed on a quartz plate having a flatness of 3 μm so that the side to which the mask adhesive was applied was in contact, and a load with a weight of 2 kg was applied. In this state, it was left still in an oven at 185 ° C. for 20 minutes. The flatness of the mask adhesive application surface of this frame was measured.

(Example 5)
The pellicle frame was placed on a quartz plate having a flatness of 3 μm so that the side to which the mask adhesive was applied was in contact, and a load with a weight of 2 kg was applied. In this state, it was allowed to stand in an oven at 185 ° C. for 15 hours. The flatness of the mask adhesive application surface of this frame was measured.

(Example 6)
The flat pellicle frame was placed on a quartz plate with a flatness of 3 μm so that the side of the pellicle frame where the mask adhesive was applied, and a load was applied using a weight of 0.5 kg. In this state, it was allowed to stand in an oven at 185 ° C. for 15 hours. The flatness of the mask adhesive application surface of this frame was measured.

(Example 7)
The pellicle frame was placed on a quartz plate having a flatness of 3 μm so that the side to which the mask adhesive was applied was in contact, and a load was applied using a weight of 20 kg. In this state, it was allowed to stand in an oven at 185 ° C. for 2 hours. The flatness of the mask adhesive application surface of this frame was measured.

(Comparative Example 1)
The flat pellicle frame was placed on a quartz plate having a flatness of 3 μm so that the side to which the mask adhesive was applied was in contact, and a weight of 2 kg was applied to the pellicle frame for 2 hours at room temperature. The flatness of the mask adhesive application surface of this frame was measured.

(Comparative Example 2)
It was placed on a quartz plate with a flatness of 15 μm so that the side of the pellicle frame to which the mask adhesive was applied was in contact, and a weight of 2 kg was applied to the pellicle frame and left in an oven at 185 ° C. for 2 hours. The flatness of the mask adhesive application surface of this frame was measured.

  The above measurement results are summarized as shown in Table 1 below.

1: Pellicle film 2: Adhesive layer 3: Pellicle frame 4: Adhesive layer for adhesion 5: Exposure master 6: Pellicle 7: Base (quartz plate)
8: Press plate (quartz plate)
9: Load

Claims (7)

  A method for manufacturing a pellicle, comprising the step of heat-treating a pellicle frame placed on a flat surface under a load.   The method for manufacturing a pellicle according to claim 1, wherein the flatness of the flat surface is 5 µm or less.   The method for producing a pellicle according to claim 1, wherein the temperature of the heat treatment is 140 to 250 ° C.   The method for producing a pellicle according to claim 1, wherein the load is about 4.90 to about 196 N (0.5 to 20 kg weight).   The method for producing a pellicle according to any one of claims 1 to 4, wherein a pellicle frame made of a material having a Young's modulus of 1 to 80 GPa is used.   The method for producing a pellicle according to any one of claims 1 to 5, wherein a pellicle frame made of an aluminum alloy is used.   The pellicle film is manufactured by the method for manufacturing a pellicle according to any one of claims 1 to 6, wherein a pellicle film is stretched on one end surface of the pellicle frame via a pellicle film adhesive and an exposure original plate adhesive is provided on the other end surface. Lithography pellicle.

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