Apparatus and method for improving process uniformity of a reticle

Abstract

The application provides a device and method for improving mask process uniformity, which comprises a cover ring for wrapping four side edges of a mask, the mask being square, the cover ring comprising a square groove matched with the mask at a process position, adjacent side edges being connected through an arc-shaped groove matched with a thimble, the thimble for supporting and wrapping a corner of the mask, the thimble being movable up and down along the arc-shaped groove in the Z direction, a lower section of the thimble being arranged on a thimble support plate, the thimble support plate being movable up and down along the Z direction, and a heater for heating the mask at the process position, the heater being connected with a lower surface of the cover ring and having a through hole formed in the upper surface. The application improves the problem of uneven temperature conduction.

Description

Technical Field

[0001] This invention belongs to the field of wafer manufacturing equipment technology, and mainly relates to the production process of photomasks, and particularly to a device and method for improving the uniformity of photomask processes. Background Technology

[0002] Masks are the carriers of information such as graphic design and process technology in the wafer manufacturing process, and their quality directly affects the quality and yield of the final product. In the mask production process, to ensure stability, plasma equipment is often used for processing. Whether it is plasma etching or resist stripping, the surface treatment process is crucial.

[0003] Currently, most wafer masks are relatively thick and square in structure. For example, a 6-inch quartz substrate mask is about 6.35 mm thick and weighs over 400 grams, making conventional transfer and lifting mechanisms in wafer fabrication processes unsuitable. This has led to the emergence of customized equipment designs in the market, with the most representative example being the lifting mechanism within the process chamber. Figure 1 Similar to the example shown. Figure 1 In the middle: After the automatic conveying mechanism delivers the mask into the cavity, it controls the lifter to rise, and the lift pin lifts the lifting ring. The inner boss of the lifting ring (such as...) Figure 2 (As shown) After contacting the mask, it rises to a certain position. At this time, the mask is placed on the lifting ring, the conveying mechanism leaves the cavity, and the lifter descends to the designated position for processing.

[0004] This structure avoids the passage of the conveying mechanism in and out of the chamber while realizing the smooth lifting and lowering of the mask plate in the chamber. However, it still has the following defects: 1) In the process of heating and raising the temperature of the heater as the basic condition, since the inner boss of the lifting ring has a certain thickness, the edge of the mask plate is placed on the boss, that is, there is a barrier between the bottom surface of the mask plate and the surface of the heater. Therefore, the edge of the mask plate and the center are prone to generate a large temperature difference during the process of heating. Figure 1 In the middle, the heater is set on the bottom surface of the lifting ring; 2) the avoidance design in the conveying direction has different gaps (formed by the lifting ring body, the inner boss of the lifting ring and the mask plate under the process position, such as Figure 2 As shown in the figure), the photomask substrate itself has high light transmittance, and it easily loses heat in the notch area after thermal radiation. The overall process results in extremely poor temperature uniformity (causing the center temperature of photomask 6 to be high and the edge temperature to be low), thus affecting the process stability and uniformity of the entire product manufacturing process. 3) The lifting ring design is offset from the center of gravity of the photomask, which will shorten the service life of the overall structure after long-term operation. Summary of the Invention

[0005] The purpose of this invention is to provide an apparatus and method for improving the uniformity of photomask processes, thereby mitigating the problem of uneven temperature conduction, reducing the risk of affecting the stability and uniformity of photomask processes, and thus increasing the yield of photomask products. The technical solution adopted is as follows: An apparatus for improving the uniformity of photomask processes, comprising: Cover ring 1 is used to wrap the four sides 61 of the mask plate 6. The mask plate 6 is square. The cover ring 11 includes a square groove 11 that is adapted to the mask plate 6 in the process position. Adjacent sides 61 are connected by an arc groove 110. The arc groove 110 is adapted to the ejector pin 2. The ejector pin 2 is used to receive and wrap one of the top corners of the mask plate 6. It can move up and down along the arc groove 110 and along the Z direction. Its lower section is set on the ejector pin support plate 3. The ejector pin support plate 3 can move up and down along the Z direction. The heater 4 is used to heat the mask plate 6 in the process position. It is connected to the lower surface of the cover ring 1 and has a through hole for the ejector pin 2 to pass through.

[0006] Preferably, the ejector pin 2 has a support groove 21 extending along the Z direction on the side facing the mask plate 6, and the support groove 21 is adapted to the corresponding apex corner.

[0007] Preferably, a preset gap is formed between the lower surface of the mask 6 and the upper surface of the heater 4 at the process position.

[0008] Preferably, the square groove 11 has a centrally symmetrical structure, and its axis of symmetry coincides with the axis of symmetry of the cover ring 1.

[0009] Preferably, the ejector pin support plate 3 is connected to the lifting mechanism 5, and the lifting mechanism 5 is installed on the base 7.

[0010] Preferably, the number of lifting mechanisms 5 is 2, and they are arranged symmetrically about the base 7.

[0011] Preferably, the cover ring 1 and the heater 4 are connected by a limiting pin.

[0012] A method for improving the uniformity of photomask processes, based on an apparatus for improving the uniformity of photomask processes, includes the following steps: The ejector support plate 3 rises, and after the ejector pin 2 contacts the lower surface of the four corners of the mask plate 6, it continues to rise to lift the mask plate 6 and stop at the pick-up position. The ejector pin support plate 3 is driven down to the process position, and the four sides of the mask plate 6 are wrapped inside the cover ring 1, and the surface is subjected to normal plasma process treatment.

[0013] Compared with the prior art, the advantages of the present invention are: 1. The ejector pins hold the four corners of the mask plate for limiting lifting and lowering. As the mask plate descends, it stops at the appropriate process position. At this time, there is no obstruction between the bottom surface of the mask plate and the surface of the heater.

[0014] 2. In the process location, the notch is relatively small. Specifically: the four sides of the mask are wrapped inside the cover ring 1, and the four top corners are covered by the ejector pins 2.

[0015] 3. Dual-motor synchronization and a lift pin ensure that the mask's center of gravity remains centered during lifting, greatly improving the overall structural stability and reliability, and providing multiple process positions for different process requirements. In contrast, conventional plasma equipment uses cylinders or a separate motor to lift the mask within the processing chamber. Due to the offset of the lifting ring's center of gravity, this can easily lead to lifting vibrations, shortening the lifespan of the lifting mechanism. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a conventional photomask lifting system; Figure 2 for Figure 1 Detailed image of the middle lifting ring; Figure 3 Top view of a device for improving the uniformity of photomask processes; Figure 4 This is a schematic diagram of the rising image capture position; Figure 5 This is a schematic diagram showing the descent to the process location; Figure 6 A structural diagram showing the fit between the ejector pin and the apex corner; Figure 7 A schematic diagram of the preset gap formed between the mask and the heater at the process location; Figure 8 This diagram illustrates how the cap ring is secured. Figure 9 This is a schematic diagram showing the contact area between the ejector pin and the mask in the prior art; Figure 10 This is a structural diagram of the support groove for the ejector pin; Figure 11 This is a three-dimensional view of the heater; Figure 12 This is a three-dimensional diagram of the cover ring.

[0017] Among them, 1-cover ring, 11-square groove, 110-arc groove, 12-inner circular edge, 13-inner square hole; 2-Ejector pin, 21-Support groove, 3-Ejector pin support plate, 4-Heater, 41-Heating zone; 5- Lifting mechanism, 6-Mask, 61-Side, 7-Base. Detailed Implementation

[0018] The apparatus and method for improving the uniformity of mask processing according to the present invention will now be described in more detail with reference to the schematic diagrams, which illustrate preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0019] like Figures 3-12 An apparatus for improving the uniformity of photomask processes, comprising: The cover ring 1, made of insulating material or other material that does not react with plasma, is used to wrap the four sides 61 of the mask 6. It includes a square groove 11 adapted to the mask 6 in the process position. Adjacent sides 61 are connected by an arc groove 110, which is adapted to the ejector pin 2. Among them, the square groove 11 and the arc groove 110 are through grooves along the Z direction.

[0020] Ejector pin 2, made of insulating material or other material that does not react with plasma, is used to receive and wrap one corner of mask plate 6. It can move up and down along Z along arc groove 110. Its lower section is set on ejector pin support plate 3. Ejector pin support plate 3 can move up and down along Z. and heater 4, used to heat the mask plate 6 at the process position, which is connected to the lower surface of the cover ring 1, and has a through hole for the ejector pin 2 to pass through, such as Figure 7 , Figure 11 As shown.

[0021] The heating zone 41 of heater 4 is flush with the lower surface of square groove 11 (lower surface of cover ring 1), such as Figure 4 As shown.

[0022] In the process position, the upper surface of the mask 6 can be flush with the square groove 11, or it can be higher or lower than the upper surface of the square groove 11, and a small gap is formed between the side 61 of the mask 6 and the square groove 11.

[0023] Regarding the design of the ejector pin 2 enclosing the square mask plate 6: The ejector pin 2 has a support groove 21 extending along the Z direction on the side facing the mask plate 6, and the support groove 21 is adapted to the corresponding top corner.

[0024] In this embodiment, "the support groove 21 is adapted to the corresponding apex corner" means: such as Figures 6-7 As shown, the top corner of the mask plate 6 in the process position is located inside the support groove 21, the lower end face of the top corner is in contact with the inner wall of the plane of the support groove 21, and the outer side of the top corner forms a small gap with the arc-shaped inner wall of the support groove 21.

[0025] like Figure 6 As shown, the outer surface of the plane where the ejector pin 2 contacts the mask plate 6 has a protruding design (the arc-shaped wall of the support groove 21), which covers the four corners of the mask plate as much as possible, reduces the heat radiation range during the process, and makes the space around the mask plate 6 (photomask) relatively uniform. In this embodiment, the area where the ejector pin 2 contacts the mask 6 is smaller than the accessible area of ​​a typical mask. The area where the ejector pin 2 contacts the mask 6 is typically 5mm or less from the lower surface to the edge. Figure 9 As shown, the contact points are located at the four corners of the mask, which greatly reduces the temperature difference between the edge and center of the mask.

[0026] The contact area between ejector pin 2 and the general mask, i.e. Figure 2 The contact area between the inner boss of the lifting ring and the mask plate, i.e. Figure 9 The cross-sectional area in the middle.

[0027] In addition, the middle section of ejector pin 2 (the first and last sections of the curved inner wall) is designed with an angle buffer to prevent misalignment during the film picking process. Figure 10 As shown, the arrow points downwards. When the mask 6 is offset during placement, it falls onto the inclined surface of the ejector pin 2 and will fall to the bottom due to gravity and angle.

[0028] like Figure 10 As shown, the arc-shaped inner wall of the ejector pin 2 includes a first segment, an arc-shaped segment, and a tail segment connected in sequence. Both the first segment and the tail segment are inclined surfaces.

[0029] Figure 7 The sectional view can be formed by cutting along the diagonal of the square groove 11, with the limiting pin disposed on the diagonal. In other embodiments, the limiting pin can be disposed at any position between the heater and the cover ring that does not interfere with other components.

[0030] To prevent damage to the mask substrate or coating due to excessive heater temperature, a certain gap is left between the lower surface of the mask at the process location and the upper surface of the heater (heating area 41). Figure 7 As shown in the figure, the gap size can be set and adjusted according to the process effect and requirements to adjust the lifting position of the ejector pin.

[0031] To ensure that the lower surface of the mask 6 and the upper surface of the heater 4 form a gap as shown in the image, the process position is as follows: Figure 7 The preset gap shown (the gap is small, and the preset gap can be adjusted according to actual process requirements; the preset gap is usually less than the thickness of the mask plate 6 itself) adopts the following scheme: The upper surface of heating zone 41 is flush with the heater body; The heating zone 41 is not higher than the lower end face of the square groove 11; for example Figure 7As shown, the two are aligned; In the process position, the support groove 21 on the ejector pin 2 is located above the heater 4, and the mask plate 6 is completely located within the square groove 11.

[0032] To improve heating uniformity, the square groove 11 is designed as a centrally symmetrical structure, with its axis of symmetry coinciding with the axis of symmetry of the cover ring 1 and the axis of symmetry of the heater 4.

[0033] The pin support plate 3 is connected to the lifting mechanism 5, and the lifting mechanism 5 is installed on the base 7.

[0034] To improve the lifespan of the lifting mechanism, the number of lifting mechanisms 5 is 2, and they are arranged symmetrically about the base 7.

[0035] Regarding the installation method of heater 4: The heater 4 is fixedly mounted (existing technology), and both the base 7 and the ejector pin support plate 3 are annular to avoid the components that fix the heater 4.

[0036] like Figure 7 As shown, in the process position, the mask is wrapped inside, with no surrounding material. Figure 1 The design gaps shown indicate that the heat radiation and heat dissipation areas of the photomask are relatively consistent, which makes it less likely to cause uneven photomask temperature and improves the overall process uniformity.

[0037] In this embodiment, the cover ring 1 and the heater 4 are connected by a limiting pin, such as... Figure 8 As shown; furthermore, the cover ring 1 has an outer circle and an inner square shape, and the cover ring 1 is engaged with the heating zone 41 through the inner square hole 13. The inner circular edge 12 of the cover ring 1 is engaged with the outer edge of the heater 4.

[0038] The limiting pin is fixed to the heater body of the heater 4 by threads. The bottom surface of the cover ring 1 has a hole that matches the limiting pin. The cover ring 1 is engaged with the limiting pin through the hole on the bottom surface.

[0039] like Figure 11 As shown, the heater 4 includes a heater body and a heating zone 41 embedded in the heater body. The heater body has a through hole to avoid the ejector pin 2.

[0040] It should be noted that, due to the viewing angle, the outer circular edge of the cover ring 1 extends to the outside of the heater 4 (e.g., Figure 7 As shown), this structural feature cannot be found in Figures 4-5 It is displayed intuitively in the text.

[0041] In addition, the inner side and upper surface of the cover ring 1 can be matte-finished according to process requirements, such as hard anodizing of metal materials, to reduce the impact of heat radiation on the process effect and improve the stability of the process.

[0042] Working principle: After the automatic conveying mechanism introduces the photomask into the process cavity, the lifting mechanism drives the ejector pin support plate 3 to rise via dual motors. Once the ejector pins contact the lower surfaces of the four corners of the photomask, the mechanism continues to rise, lifting the photomask and stopping it at the wafer pick-up position. Figure 4 As shown.

[0043] The conveyor mechanism returns to the outside of the cavity, and the ejector pin support plate 3 is driven to descend to the process position. The four sides of the mask plate wrap around the inside of the cover ring, as shown. Figure 5 As shown.

[0044] The surface undergoes normal plasma processing.

[0045] In summary, this embodiment designs a lifting structure for a square photomask. The lifting pin 2 is driven to rise, fall, and stop by a dual-motor synchronous lifting mechanism or other moving components, so that the bottom surface of the entire photomask 6 (photomask) is placed flat in the heating area (heating zone 41) when it is in the process position. The cover ring 1 and the ejector pin 2 wrap around the photomask 6, reducing the plasma that can be contacted around it and making the radiation range around it relatively uniform. This reduces the impact of uneven heat in the process and improves the uniformity and stability of the photomask process.

[0046] Furthermore, this device is not only suitable for lifting and lowering square photomasks, but can also be used for wafers or other process products.

[0047] The ejector pin 2 and the cover ring 1 must be insulated and will not react with plasma. The materials are not limited to metals such as aluminum alloy and stainless steel, ceramics containing oxides, nitrides, and carbides, quartz of different purity and hardness, engineering plastics such as PTFE, ULTEM, PI, and PEEK, etc. Surface treatment is not limited to hard anodizing and natural anodizing.

[0048] The lifting mechanism 5 is not limited to motor lifting; it can be other moving parts that enable the structure to rise or fall.

[0049] The ejector pin 2 is not limited to the four corners of the product; it can be designed to limit the four sides of the product, so that the structure can smoothly pick up and put down the product for processing.

[0050] The structure of the cover ring 1 + heater 4 is not limited to the fixed connection with the limiting pin. It can be fixed in other ways so that the cover ring can be fixed. It can also be combined into one, that is, the heater body is an irregular design with a groove on the upper part to wrap the mask or wafer and other products.

[0051] The overall structure is not limited to lifting square products; the shape of the cover ring, heater, and lift pin can also be changed to apply to products of other shapes.

[0052] The above are merely preferred embodiments of the present invention and do not constitute any limitation on the present invention. Any equivalent substitutions or modifications made by those skilled in the art to the technical solutions and content disclosed in the present invention without departing from the scope of the present invention shall be deemed to have remained within the protection scope of the present invention.

Claims

1. An apparatus for improving the uniformity of photomask processing, characterized in that, include: A cover ring (1) is used to wrap the four sides (61) of a mask (6). The mask (6) is square. The cover ring (1) includes a square groove (11) adapted to the mask (6) in the process position. Adjacent sides (61) are connected by an arc groove (110). The arc groove (110) is adapted to the ejector pin (2). The ejector pin (2) is used to receive and wrap a corner of the mask plate (6). It can move up and down along the arc groove (110) and along the Z direction. Its lower section is set on the ejector pin support plate (3). The ejector pin support plate (3) can move up and down along the Z direction. and heater (4), used to heat the mask plate (6) in the process position, which is connected to the lower surface of the cover ring (1) and has a through hole for the ejector pin (2) to pass through.

2. The apparatus for improving the uniformity of mask processing according to claim 1, characterized in that, The ejector pin (2) has a support groove (21) extending along the Z direction on the side facing the mask plate (6), and the support groove (21) is adapted to the corresponding top corner.

3. The apparatus for improving the uniformity of mask processing according to claim 1, characterized in that, A preset gap is formed between the lower surface of the mask (6) and the upper surface of the heater (4) at the process position.

4. The apparatus for improving the uniformity of mask processing according to claim 1, characterized in that, The square groove (11) is a centrally symmetrical structure, and its axis of symmetry coincides with the axis of symmetry of the cover ring (1).

5. The apparatus for improving the uniformity of mask processing according to claim 1, characterized in that, The pin support plate (3) is connected to the lifting mechanism (5), which is installed on the base (7).

6. The apparatus for improving the uniformity of mask processing according to claim 5, characterized in that, The number of lifting mechanisms (5) is 2, and they are symmetrically arranged about the base (7).

7. The apparatus for improving the uniformity of mask processing according to claim 1, characterized in that, The cover ring (1) is connected to the heater (4) by a limiting pin.

8. A method for improving the uniformity of photomask processes, based on the apparatus for improving the uniformity of photomask processes according to claim 1, characterized in that, Includes the following steps: The ejector support plate (3) rises, and after the ejector (2) contacts the lower surface of the four corners of the mask plate (6), it continues to rise to lift the mask plate (6) and stop at the pick-up position; The ejector pin support plate (3) is driven down to the process position, and the four sides of the mask plate (6) are wrapped inside the cover ring (1), and the surface is normally subjected to plasma process treatment.

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