JP2021060555A - Assembly comprising pellicle and dedicated pellicle case thereof - Google Patents

Abstract

To provide an assembly of a pellicle and a dedicated pellicle case thereof with reduced tendency to cause a deterioration in the flatness of the frame of a pellicle for lithography and, in turn, provide a method that prevents strain transfer to an exposure original plate.SOLUTION: A pellicle frame 2 and a tray part 9 of a dedicated pellicle case are each provided with structure means 4 for holding an adhesive layer 5 of a pellicle in a state of floating from the tray part of the dedicated pellicle case.SELECTED DRAWING: Figure 2

Description

The present invention relates to an assembly comprising a lithography pellicle used as a dust repellent for a lithography mask when manufacturing a semiconductor device such as an LSI or a super LSI or a liquid crystal display board, and a dedicated pellicle case thereof.

In the manufacture of semiconductors such as LSIs and VLSIs or the manufacture of liquid crystal display boards, patterns are produced by irradiating semiconductor wafers or original plates for liquid crystals with light. Since this dust absorbs light and bends the light, the transferred pattern is deformed, the edges become rough, and the base becomes black and dirty, which impairs the dimensions, quality, appearance, etc. There was a problem of being In the present invention, the "exposure original plate" is a general term for a mask for lithography and a reticle (hereinafter, also abbreviated as "mask").

These operations are usually performed in a clean room, but it is difficult to keep the mask clean even in this clean room, so a pellicle that allows light for exposure to avoid dust is attached to the surface of the mask. The method of wearing is taken. In this case, dust does not adhere directly to the surface of the mask, but adheres to the pellicle film. Therefore, if the focus is on the mask pattern during lithography, the dust on the pellicle film is irrelevant to transfer. Become.

The basic structure of such a pellicle is composed of a pellicle frame and a pellicle film stretched on the pellicle frame. This pellicle film is made of nitrocellulose, cellulose acetate, fluoropolymer, etc. that allows light (g-line, i-line, 248 nm, 193 nm, etc.) used for exposure to pass through well, and the pellicle frame is A7075 treated with black alumite or the like. , A6061, A5052 and other aluminum alloys, stainless steel, polyethylene and the like.

A good solvent for the pellicle film is applied to the upper surface (upper end surface) of the pellicle frame, and the pellicle film is attached to the pellicle frame and air-dried to be adhered, or an adhesive such as acrylic resin, epoxy resin or fluororesin is used. Is glued using. Further, in order to attach a mask to the lower surface (lower end surface) of the pellicle frame, the purpose is to protect the mask adhesive layer made of polybutene resin, polyvinyl acetate resin, acrylic resin, silicone resin, etc. and the adhesive layer. A protective sheet (hereinafter, also referred to as “separator”) made of a releasable liner is provided.

The pellicle configured in this way is installed so as to surround the pattern area formed on the surface of the mask, and is provided to prevent dust from adhering on the mask. Dust outside the pellicle is isolated from each other so that it does not adhere to the pattern surface.

By the way, in recent years, LSI design rules have been miniaturized to sub-quarter micron, and along with this, the wavelength of the exposure light source has been shortened, that is, the KrF excimer laser (248 nm), which has been the mainstream until now. Is shifting to ArF excimer laser (193 nm), ArF excimer laser (193 nm) immersion exposure, and the like.

As described above, when the wavelength of exposure is shortened and the exposure resolution is increased, there is a concern that even pattern deformation and distortion, which have not been a problem so far, affect the yield. The deformation and distortion of this pattern are largely due to the deformation and distortion of the mask itself, and the main cause of the defect is the deformation and distortion that accompany the application of the pellicle to the mask, and the deformation and distortion of the pellicle itself. Is known to be transmitted to the mask and have an adverse effect.

Therefore, attempts have been made to reduce the influence on the mask, and Patent Documents 1 and 2 describe a lithographic pellicle in which the flatness of the surface of the mask pressure-sensitive adhesive layer of the pellicle is 15 μm or less. However, even a pellicle created with the flatness of the adhesive layer of the pellicle has a problem that the shape at the time of completion of the pellicle may not be stably maintained by storing the pellicle in a container after completion.

Japanese Patent No. 5411200 Japanese Patent No. 5999843

The present invention has been made in view of such circumstances, and an object of the present invention is an assembly composed of a highly flat lithography pellicle capable of stably reducing deformation and distortion of an exposure original plate and a special pellicle case thereof. Is to provide.

Conventionally, a lithography pellicle having a high flatness (hereinafter, also simply referred to as a “high flat pellicle”) has been manufactured by controlling the flatness of a rectangular pellicle frame (hereinafter, also simply referred to as a “frame”). After the pellicle was completed, the present inventor stored the pellicle in a special pellicle case (provided with a lid and a tray), took out the pellicle, attached it to a mask, and repeated the experiment. As a result, the pellicle was manufactured under the same conditions. It was found that the effect of distortion on the mask is different even if the is pasted.

Then, the present inventor further considered the cause, and found that by storing the pellicle in a special pellicle case, a mask adhesive layer to which a protective sheet (separator) was attached (hereinafter, simply "adhesive layer"). ”) Contacted the tray of the special pellicle case, and it was confirmed that the flatness of the adhesive layer was worse than the flatness immediately after production. It was also confirmed that the degree of deterioration of the flatness of the pressure-sensitive adhesive layer varies from individual to individual, and that the smaller the deterioration of the flatness, the smaller the distortion of the mask when the pellicle is attached. These findings were first discovered by the present inventor, and by storing the pellicle in a conventional general pellicle case, the flatness of the adhesive layer deteriorates, which is a mask when the pellicle is attached. The present inventor is the first to pay attention to the causal relationship that causes the deformation and distortion of the pattern, and eventually the deformation and distortion of the pattern, and to clarify it.

Furthermore, the present inventor has verified that the pellicle in which the adhesive layer is held in a non-contact state with the tray portion of the dedicated pellicle case without being stored in the dedicated pellicle case after the completion of the pellicle has little distortion of the mask. This is the result of the present invention.

That is, the assembly of the lithography pellicle and its dedicated pellicle case according to the present invention is held in a state of being floated from the tray portion so that the sticking surface of the adhesive layer does not come into contact with the tray portion of the dedicated pellicle case. It is characterized in that it is stored in a dedicated pellicle case, and as a structural means for holding the adhesive layer in a floating state from the tray portion of the dedicated pellicle case, for example, a notch portion (notch portion) on the outer peripheral portion of the pellicle frame. A structure is provided so as to provide a step) or a protrusion, and to receive the notch or the protrusion on the outer peripheral portion of the pellicle frame in the tray portion of the dedicated pellicle case. In consideration of the practical aspect of the pellicle, in order to correspond to the current pellicle extraction device (pellicle auto mounter), the pellicle is moved upward without interfering with the existing jig holes provided at each of the two long sides. By providing a structure that does not become a resistance when pulling up to, there is no need to change the setting of the pellicle auto mounter, it can be used as it is, and other additional operations can be performed while maintaining the conventional operation. It is preferable to have a structure in which the pellicle can be smoothly moved and taken out, and the adhesive layer of the pellicle can be stored in a non-contact floating state from the tray portion.

According to the present invention, when the completed pellicle is stored in the dedicated pellicle case, the surface to which the protective sheet (separator) of the adhesive layer is attached is floated so as not to come into contact with the dedicated pellicle case. As a result, the flatness of the sheet-attached surface of the adhesive layer can be maintained in the same state as before the case is stored, and when the pellicle is attached to the mask, the effect on the distortion of the mask can be suppressed to a small extent. It is possible to provide a pellicle for high flat lithography that can be used.

It is the schematic sectional drawing of 1 Embodiment of the assembly of the pellicle which concerns on this invention and the pellicle case for exclusive use thereof. It is the schematic sectional drawing of 1 Embodiment of the assembly of the pellicle which concerns on this invention and the pellicle case for exclusive use thereof. It is schematic cross-sectional view of 1 Embodiment of the assembly of the pellicle which concerns on this invention and its exclusive pellicle case when the protective sheet (separator) of the pressure-sensitive adhesive layer is not used.

Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings, but the present invention is not limited to this embodiment. The lithography pellicle housed according to the present invention is characterized in that the flatness of the adhesive layer for attaching a mask does not deteriorate even if the pellicle is stored in a special pellicle case after completion. FIG. 1 is a schematic cross-sectional view of the assembly 10 of the pellicle according to the present invention and its dedicated pellicle case, and FIG. 2 shows an embodiment when a separator 3 is provided, and FIG. 2 shows the pellicle according to the present invention and its dedicated pellicle. FIG. 3 is a schematic cross-sectional view of the case assembly 10, wherein a notched step 6 is provided as a structural means that does not protrude from the outside of the pellicle frame 2, and FIG. 3 shows the pellicle according to the present invention and its dedicated pellicle case. It is the schematic cross-sectional view of the assembly 10, and shows the embodiment when the separator is not provided.

In order to achieve the above characteristics, it is necessary to give the outer surface of the pellicle frame 2 and the tray portion 9 of the dedicated pellicle case each having a characteristic shape. As a specific example, when the pellicle frame is stored in a special pellicle case, the outside of the frame can be stabilized so that the adhesive layer 5 sticking surface (lower end surface) of the lower end surface of the frame can be stabilized in a hollow state. Any protrusion or notch (step) can be provided on the side surface as an option. In that case, the dedicated pellicle case requires a structure (structural means) having a shape that receives protrusions or steps of the frame as the structural means 4 that supports the pellicle. As shown in FIGS. 1 to 3, the dedicated pellicle case includes a lid portion 8 and a tray portion 9. Further, in FIGS. 1 to 3, reference numeral 1 indicates a pellicle film.

As a method of installing the adhesive layer in a floating state in the dedicated pellicle case, a plurality of holes are provided on the outer surface of the pellicle frame, and the same number of protrusions as the holes that engage with the holes to support the pellicle frame are provided. A structural means composed of an object and a structure supporting the object, for example, a structural means having a pin-shaped protrusion may be provided in the tray portion of the dedicated pellicle case, and the structural means may be inserted into the hole to be gripped. However, in this case, it is necessary to add the operation of pulling out the pin to the operation of taking out the pellicle from the dedicated pellicle case. Currently, when removing a pellicle from a dedicated pellicle case, a dedicated device called a pellicle auto mounter is used, so it is required to have a pellicle frame and a dedicated pellicle case structure that allows the pellicle to be taken out with the same operation as before. Has been done. Considering this situation, it takes time to implement this embodiment, and it cannot be said that it is the best mode.

In the present invention, by combining a pellicle frame having the above structure and its dedicated pellicle case, that is, as an assembly, the pellicle is stored in the dedicated pellicle case and attached to the mask after completion. Since the sticking surface of the adhesive layer for sticking the mask can be lifted from the tray and maintained in a non-contact state, the flatness immediately after the completion of the pellicle can be completely maintained, and the flat surface of the mask generated when the pellicle is stuck can be obtained. Pellicle-Induced Distortion can be significantly reduced.

In the present invention, it is preferable that the structure of the outer surface of the lithographic pellicle frame has as little overhang as possible on the outer peripheral portion. Therefore, it is also a significant option to make the coated end face of the adhesive layer for attaching the mask smaller and to provide a step on the outside of the pellicle frame.

The shape and number of structural means (projections, notches, etc.) provided in the pellicle frame for floating and storing the adhesive layer for mask attachment in the special pellicle case and the tray part of the special pellicle case are pellicle. Must be stable enough to hold inside the case.

Further, since the pellicle produced by the present invention can maintain the state in which the adhesive layer for attaching a mask is suspended in the air when stored in a special pellicle case, the adhesive layer for attaching a mask is generally used. The protective sheet (separator) can be abolished.

If the separator is abolished, not only the material and manufacturing man-hours will be reduced, but also the separator will not need to be attached or detached. Therefore, it can be expected that the distortion of the flat surface of the mask generated when the pellicle is attached to the mask is further reduced and stabilized.

Next, the examples of the present invention will be specifically described. Although the examples and the comparative examples are examples of masks, it goes without saying that the results can be applied to the reticle as well.

The evaluation of the effect of the present invention was carried out as follows. First, the flatness of the mask substrate used for attachment was measured with Tropel's FlatMaster, and then the highly flat pellicle to be evaluated was attached to this mask substrate, and the flatness of the mask substrate was measured in the same manner. The difference in mask strain (difference in flatness) before and after pasting was measured, and this difference (increase in mask strain due to pasting) was used as the result of each pellicle.

[Reference example]
In addition, as a comparison target for confirming the effect of the present invention, the mask sticking behavior of the pellicle not stored in the case was also confirmed (reference example).

That is, as a reference pellicle frame, the outer dimensions of the frame are 149 mm × 115 mm × 3.15 mm (height), the frame width is 2 mm, and the shapes of the four corners draw curves of outer R5 and inner R3, and the surface. Black alumite was applied to the frame, and a frame with a frame flatness of 9 μm was prepared. A pellicle was created using this frame. No separator was provided to protect the adhesive layer.

Next, the flatness of the prepared mask was measured by Tropel's FlatMaster and found to be 305 nm. The above reference pellicle was attached to this mask substrate under the conditions of a weight of 5 kg for 30 seconds, and the mask flatness was measured again. When measured, it was 340 nm. That is, the distortion difference of the mask substrate before and after pasting was 35 nm.

[Example 1]
As a pellicle frame, a frame 2 having an outer frame size of 149 mm × 115 mm × 3.15 mm, a frame width of 2 mm, four corners having outer R5 and inner R3, and black alumite on the surface is prepared. did. Notch steps (notch portions) 6 having a thickness of 1 mm and R1 are provided on the outer surface and the portion 1 mm from the lower end surface of the four corner portions of the frame, respectively (see FIG. 2). The frame flatness was 8 μm. A pellicle was created using this frame 2. No separator was provided to protect the pressure-sensitive adhesive layer (see FIG. 3). The completed pellicle was stored in a special pellicle case. The tray portion 9 of the dedicated pellicle case is a structure (pellicle) having a shape that supports the pellicle so that the adhesive layer can be floated and stored by receiving the notch steps 6 installed on the outer surfaces of the four corner portions. (Structural means) 4 is provided.

Next, when the flatness of the prepared mask (not shown) similar to that used in the above reference example was measured by FlatMaster of Tropel, the flatness of the mask was 301 nm. The pellicle was taken out from the dedicated pellicle case, the pellicle was attached to the mask substrate under the condition of a weight of 5 kg for 30 seconds, and the mask flatness was measured again and found to be 337 nm. That is, the distortion difference of the mask substrate before and after pasting was 36 nm.

[Example 2]
A frame 2 having the same shape as that of Example 1 was prepared, and the flatness of the frame was measured and found to be 7 μm. A pellicle was prepared in the same manner as in Example 1, and finally, after the separator 3 was attached to the surface to which the adhesive layer was attached, the pellicle was stored in a special pellicle case having the same shape as in Example 1.
Next, when the flatness of the prepared mask similar to that used in the above reference example was measured by FlatMaster of Tropel, the flatness of the mask was 297 nm. The pellicle was taken out from the special pellicle case, the separator 3 was peeled off, the pellicle was attached to the mask substrate under the condition of a weight of 5 kg for 30 seconds, and the mask flatness was measured again and found to be 336 nm. That is, the distortion difference of the mask substrate before and after pasting was 39 nm.

[Example 3]
As a pellicle frame, the outer dimensions of the frame are 149 mm × 115 mm × 3.15 mm, the frame width is 2 mm, and notch steps 6 as shown in FIG. 2 are provided at four locations around 60 mm from the center of the long side of the frame. A frame 2 having black alumite having four corners having outer R5 and inner R3 was prepared. The flatness of the frame was measured and found to be 8 μm. A pellicle was created using this frame 2. The separator 3 that protects the pressure-sensitive adhesive layer 5 was not provided. The completed pellicle was stored in a special pellicle case. The tray portion 9 of the dedicated pellicle case has a structural means 4 capable of receiving a step 6 of four notched portions provided on the long side of the frame and allowing the adhesive layer to float and be stored.
Next, when the flatness of the prepared mask similar to that used in the above reference example was measured by FlatMaster of Tropel, the flatness of the mask was 303 nm. The pellicle was taken out from the dedicated pellicle case, the pellicle was attached to the mask substrate under the condition of a weight of 5 kg for 30 seconds, and the mask flatness was measured again and found to be 339 nm. That is, the distortion difference of the mask substrate before and after pasting was 36 nm.

[Example 4]
A frame 2 having the same shape as that of Example 3 was prepared, and the flatness of the frame was measured and found to be 8 μm. A pellicle was prepared in the same manner as in Example 3, and finally, after the separator 3 was attached to the surface to which the adhesive layer was attached, the pellicle was stored in a special pellicle case having the same shape as in Example 3.
Next, when the flatness of the prepared mask similar to that used in the above reference example was measured by FlatMaster of Tropel, the flatness of the mask was 299 nm. The pellicle was taken out from the dedicated pellicle case, the separator was peeled off, the pellicle was attached to the mask substrate under the condition of a weight of 5 kg for 30 seconds, and the mask flatness was measured again and found to be 337 nm. That is, the distortion difference of the mask substrate before and after pasting was 38 nm.

[Comparative Example 1]
When a frame having the same shape as that of Example 1 was prepared and the flatness of the frame was measured, it was 7 μm. A pellicle was prepared in the same manner as in Example 1, and finally, a separator was attached to the surface to which the adhesive layer was attached, and then stored in a general pellicle case. Unlike the dedicated pellicle case used in Examples 1 to 4, the pellicle tray was stored in a state where the adhesive layer protected by the separator was placed on the mounting table.
Next, when the flatness of the prepared mask similar to that used in the above reference example was measured by FlatMaster of Tropel, the flatness of the mask was 305 nm. The pellicle was taken out from the pellicle case, the separator was peeled off, the pellicle was attached to the mask substrate under the condition of a weight of 5 kg for 30 seconds, and the mask flatness was measured again and found to be 376 nm. That is, the distortion difference of the mask substrate before and after pasting was 62 nm.

Table 1 summarizes the above results.

First, a group of examples adopting "a state in which the mask adhesive floats from the tray portion" occurs when the pellicle is attached, as compared with Comparative Example 1 in which "a state in which the mask adhesive layer is placed on the tray portion" is adopted. The significant reduction in the amount of strain transfer to the flat surface of the mask shows the remarkable progress brought about by the present invention. That is, the deterioration of the flatness of the pressure-sensitive adhesive caused by the contact of the mask pressure-sensitive adhesive layer with the tray portion was proved, and an effective solution thereof was shown.

Next, the results of Examples 1 and 3 were almost the same as those of the reference example in which the case storage was skipped. The fact that the combination (assembly) of the dedicated pellicle case and the pellicle of the present invention was a separator-free pellicle. It means that we have succeeded in designing a highly reliable case that enables storage of the.

On the other hand, in Examples 2 and 4, even when the separator is attached, that is, even when the flatness of the adhesive layer is slightly deteriorated by the pressurization at the time of attachment, "the mask adhesive layer floats from the tray portion". It proves that if it is stored in a special pellicle case that makes it "state", there will be almost no further deterioration.

Further, in Examples 2 and 4, by attaching the separator, the effect of preventing volatilization by the separator and the effect of preserving the adhesive strength due to the effect of avoiding dust capture can be enjoyed, and the adhesive layer is not in contact with the tray portion. It is also an excellent embodiment in which direct vibration from the air can be avoided, and thus maintenance of high flatness can be promoted.

As described above, from the results of Examples 1 to 4, when the pellicle is stored in the dedicated pellicle case, the adhesive is stored by storing the sticking end face of the mask adhesive layer without contacting the tray portion of the case. The layer can be attached to the mask while maintaining the excellent flatness of the end face immediately after completion. As a result, the distortion of the mask when the pellicle is attached to the mask can be reduced.

Further, by not using the separator used for the purpose of protecting the pressure-sensitive adhesive layer, the force applied to the sticking end face of the pressure-sensitive adhesive layer can be eliminated, and the flatness of the sticking end face of the pressure-sensitive adhesive layer can be eliminated. It was confirmed that the flatness of the frame immediately after the completion of the pellicle can be maintained, and the transfer of distortion when the mask is attached can be further reduced.

In the embodiment of the present invention, as a structural means for storing the pressure-sensitive adhesive layer in a special pellicle case in a floating state, an embodiment in which a protrusion such as a pin is inserted into the pellicle frame is not implemented. The reason is the result of considering that it can correspond to the taking-out operation of the currently used pellicle auto mounter as it is. However, the present invention also covers an embodiment in which the pellicle is fixed by using a structure provided on the outer surface of the frame, such as a pin 7, as shown in FIGS. 1 and 3. Included in.

In order to obtain the effects of the present invention, it is required that the essential elements in the pellicle and the essential elements in the dedicated pellicle case coexist and cooperate with each other. Therefore, the subject of the invention is the assembly of the pellicle and the dedicated pellicle case.

1 Pellicle film 2 Pellicle frame 3 Separator 4 Structural means to support the pellicle 5 Adhesive layer 6 Notch step (notch)
7 Pin as part of the structural means to support the pellicle 8 Lid of the dedicated pellicle case 9 Tray of the dedicated pellicle case 10 Assembly of the pellicle and its dedicated pellicle case

Claims (10)

An assembly consisting of a pellicle and its dedicated pellicle case, the pellicle includes a rectangular pellicle frame and an adhesive layer provided on the lower end surface thereof for sticking to an exposure original plate, and the dedicated pellicle case has a lid portion. And a tray
The pellicle and its dedicated pellicle are each provided with structural means for holding the adhesive layer in a state of being floated from the tray portion of the dedicated pellicle case in the pellicle frame and the tray portion. An assembly consisting of a case. The structural means provided in the pellicle frame is a notch or a protrusion due to a step provided on the outer surface of the pellicle frame, and the structural means provided in the tray is the notch or the notch or a protrusion. The assembly comprising the pellicle according to claim 1 and a special pellicle case thereof, which is a structure that receives a protrusion and supports the pellicle. The assembly comprising the pellicle according to claim 1 and a dedicated pellicle case, wherein the structural means provided on the pellicle frame is provided at four corners of the pellicle frame. The pellicle according to claim 1, wherein the structural means provided on the pellicle frame are provided at a total of four positions at a position at least 60 mm away from the central portion of each long side of the pellicle frame. An assembly consisting of a pellicle case. The structural means provided in the pellicle frame is a plurality of holes provided on the outer surface of the pellicle frame, and the structural means provided in the tray portion engages with the holes to form the pellicle frame. The assembly comprising the pellicle according to claim 1 and a special pellicle case thereof, which comprises the same number of protrusions as the holes for supporting the holes and a structure for supporting the protrusions. From the pellicle according to claim 1 and the dedicated pellicle case, wherein the pellicle is housed in the dedicated pellicle case in a state where the lower end surface of the pellicle frame is not provided with a separator for protecting the adhesive layer. Assembly. The structural means provided on the pellicle frame and the tray portion can move smoothly without performing other operations when the pellicle is lifted upward, and the pellicle auto mounter can be used as it is without changing the setting. A possible assembly comprising the pellicle according to claim 1 and a pellicle case dedicated to the pellicle. A pellicle including a rectangular pellicle frame and an adhesive layer provided on the lower end surface thereof for sticking to an exposure original plate, and the pellicle frame has the adhesive from a tray portion of a pellicle case accommodating the pellicle. A pellicle characterized in that a structural means for holding the agent layer in a floating state is provided. The pellicle according to claim 8, wherein the pellicle is housed in a pellicle case without a separator for protecting the adhesive layer provided on the lower end surface of the pellicle frame. A pellicle case for storing the pellicle according to claim 8, which includes a lid portion and a tray portion, and holds the adhesive layer of the pellicle in a state of floating from the tray portion in the tray portion. A pellicle case characterized in that a structural means for the purpose is provided.

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