Mould and photoetching equipment

Abstract

The utility model discloses a mold and photoetching equipment, and belongs to the field of superconducting quantum chip manufacturing. The mold comprises a first plate sheet defining a wafer fixing area and a second plate sheet opposite to the first plate sheet. Wherein the first plate sheet is provided with a vent hole extending along the thickness direction in the fixed area, and the second plate sheet is provided with a placing hole for the wafer to pass through to be attached to the first plate sheet in a face-to-face manner; and in the thickness direction, the placing hole is opposite to the fixing area. The mold can be used for realizing proximity photoetching on a small-size wafer by using the existing photoetching equipment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of quantum information, especially the field of superconducting quantum chip manufacturing, and particularly relates to a mold and a photolithography device. BACKGROUND

[0002] In the process of integrated circuit manufacturing, the photolithography methods mainly include the following three types: contact photolithography, proximity photolithography, and projection photolithography.

[0003] Currently, in some scenarios, proximity photolithography is used in the manufacturing of superconducting quantum chips, but it is mainly used for large-size wafers and cannot be applied to small-size wafers. CONTENT

[0004] Examples of the present application provide a mold and a photolithography device, which can be used to realize proximity photolithography of small-size wafers without changing the existing photolithography device.

[0005] The scheme of the examples of the present application is implemented by the following contents.

[0006] In a first aspect, examples of the present application disclose a mold for realizing proximity photolithography of a wafer.

[0007] The mold comprises:

[0008] a first plate piece defining a wafer fixing area, the fixing area having a ventilation hole extending in a thickness direction;

[0009] a second plate piece opposite to the first plate piece, provided with a placing hole for the wafer to pass through and be attached face to face with the first plate piece;

[0010] In the thickness direction, the placing hole is opposite to the fixing area.

[0011] According to some examples of the present application, the ventilation hole is a cylindrical structure.

[0012] Alternatively, the ventilation hole is a cylindrical hole, the number of the cylindrical holes is multiple, and all the ventilation holes are uniformly distributed in the same distance between the axes of any two adjacent ventilation holes.

[0013] According to some examples of the present application, the first plate piece and the second plate piece are detachably connected.

[0014] The detachable connection of the first plate piece and the second plate piece can facilitate the replacement of any damaged plate piece for reuse, thereby reducing waste and use cost.

[0015] Alternatively, when proximity lithography is required for wafers of different sizes, the second plate with different sizes of the placement holes can be replaced. In this way, the etching requirement of different wafers can be met by adjusting the mold on demand.

[0016] According to some examples of the present application, the first plate and the second plate are bonded. Optionally, the bonding is achieved by means of a gasket with a precisely manufactured thickness. That is, the bonding agent is applied at both ends in the height direction of the gasket, and then the first plate and the second plate are respectively combined to the upper and lower end surfaces of the gasket to press the to-be-bonded stably.

[0017] According to some examples of the present application, the first plate is made of silicon sheet material; and / or, the second plate is made of silicon sheet material.

[0018] The first plate and the second plate can have the same material to facilitate process manufacturing and processing.

[0019] According to some examples of the present application, one or both of the first plate and the second plate is provided with a positioning structure.

[0020] The positioning structure can facilitate the positioning of the wafer to be lithographed, and also facilitate the positioning of the mold. Therefore, the two plates can be respectively provided with a positioning structure, and the positioning structures of the two plates are also considered to be positioned; that is, when the first plate and the second plate are assembled, the positioning structure of the first plate and the positioning structure of the second plate are implemented. And although both are described as positioning structures, the positioning structures of the first plate and the second plate can be selected to be constructed in different structures.

[0021] According to some examples of the present application, the positioning structure is a blind hole or a through hole.

[0022] According to some examples of the present application, the hole wall of the positioning structure is connected to the hole wall of the placement hole. That is, from the plane of the plate, the positioning structure and the placement hole form a closed ring pattern.

[0023] In a second aspect, examples of the present application disclose a lithography device comprising the aforementioned mold.

[0024] According to some examples of the present application, the lithography device further comprises:

[0025] A mask holder provided with an exposure window;

[0026] A rotatable dial connected to the mask holder, capable of being transferred between the exposure window area and the non-exposure area by rotation; and

[0027] A workbench opposite to the mask holder;

[0028] The worktable is used for fixing the mold, and the push piece in the exposure window area is used for contacting the first plate in the mask plate and the mold respectively through two surfaces in the thickness direction.

[0029] Advantages:

[0030] In the above implementation, the mold of the present application includes the first plate and the second plate, and the first plate is provided with the air hole, and the second plate is provided with the placing hole. In this way, the wafer to be photoetched is attached to the first plate through the placing hole of the second plate, and the wafer can also be fixed by vacuum adsorption.

[0031] On this basis, the photoetching equipment can control the position and the distance by contacting the second plate and the mask plate respectively to realize the non-contact photoetching, i.e. the proximity photoetching. Meanwhile, the above scheme can also avoid the contamination of the mask plate in the contact photoetching, and can also avoid the waste of materials and labor, and reduce the problem of shortening the service life of the mask plate caused by repeated plate washing operation. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to make the description clearer, the drawings needed in the description will be briefly introduced as follows.

[0033] Figure 1 Fig. 1 is a structure diagram of the mask plate fixing device of the photoetching equipment in the non-photoetching state of one bottom view angle in the example of the present application;

[0034] Figure 2 Fig. 2 is a structure diagram of the mask plate fixing device cooperating in the photoetching state of one bottom view angle in the example of the present application;

[0035] Figure 3 Fig. 3 is a structure diagram of the mold in three view angles in the example of the present application;

[0036] Figure 4 Fig. 4 is a structure diagram of another mold in one view angle in the example of the present application.

[0037] Explanation of reference signs:

[0038] 101 - mask plate fixing device;

[0039] 102 - exposure window;

[0040] 103 - isolator; 1031 - small ball;

[0041] 400 - mold;

[0042] 401 - first plate; 4011 - air hole;

[0043] 402 - second plate; 402a - second plate; 4021 - placement hole; 4022 - positioning structure;

[0044] 403 - adhesive layer. DETAILED DESCRIPTION

[0045] Currently, there are three main types of photolithography, namely, contact photolithography, proximity photolithography, and projection photolithography. Contact photolithography has a high resolution, a relatively low cost, and a relatively mature process, and can reach a sub-micron level.

[0046] In the implementation process of the applicant, a contact photolithography device is used. In the process of contact photolithography, the photomask plate and the sample / wafer are completely attached. However, during the attachment process, the (photo)resin on the surface of the sample is very easy to stick to the photomask plate, causing the photomask plate to be dirty.

[0047] Therefore, the dirt on the photomask plate that is reused during the second exposure can cause various components and structures in the chip to be defective. In order to improve such a defective photomask plate, cleaning is required, thereby causing material and labor waste, and more importantly, the repeated cleaning operation also seriously reduces the service life of the photomask plate.

[0048] Based on this, the applicant believes that the proximity photolithography process can be adjusted to replace the contact photolithography, thereby saving manufacturing costs and improving yield.

[0049] In the field of integrated circuit manufacturing and micro-nano processing, proximity photolithography is a traditional and important photolithography technology.

[0050] Proximity photolithography uses the transmission and blocking of light to achieve pattern transfer.

[0051] The photolithography device mainly includes a light source, a mask plate, and a silicon wafer coated with photoresist. The mask plate has a pre-designed micro-nano pattern. The light emitted by the light source can pass through the light-transmitting area on the mask plate and be blocked by the light-blocking area.

[0052] The silicon wafer is coated with photoresist sensitive to a specific wavelength. The part of the photoresist that is exposed to light will change in chemical properties, and the part that is not exposed to light will remain the same, thereby copying the pattern of the mask plate to the photoresist layer.

[0053] However, in the above process, the silicon wafer and the mask plate are not tightly attached, but maintain a small gap. The length of the gap is usually between 10 μm and 50 μm. This is also the origin of the name "proximity", that is, the mask plate is close to but not in contact with the wafer.

[0054] The main steps of the proximity photolithography process include the following steps.

[0055] (1) Silicon wafer pretreatment

[0056] First, the silicon wafer is cleaned and dried to remove surface impurities, organic matter, and water stains. Then, photoresist is spin-coated onto the silicon wafer surface. During this process, the thickness and uniformity of the photoresist significantly affect the subsequent photolithography results; therefore, the spin-coating parameters must be precisely controlled.

[0057] (2) Alignment and Exposure

[0058] The silicon wafer coated with photoresist is placed on the stage of the lithography machine, ensuring high-precision alignment between the wafer and the photomask to prevent misalignment. After alignment, exposure is performed using a light source or electron beam. Specific exposure parameters are adjusted based on factors such as the characteristics of the photoresist and the intensity of the light source.

[0059] (3) Development

[0060] After exposure, the silicon wafer is placed in the developer. Due to the difference in solubility between the illuminated and unilluminated areas of the photoresist, the photoresist modified by the light is dissolved after development, while the unilluminated portion remains—for positive photoresist. At this point, the pattern of the photomask is clearly displayed on the photoresist layer.

[0061] (4) Etching and Resin Removal

[0062] Under the protection of patterned photoresist, the pattern of the photoresist is transferred to the material layer on the surface of the silicon wafer through etching such as chemical etching or plasma etching.

[0063] After etching is completed, a photoresist remover is used to remove the remaining photoresist, and the remaining film on the silicon wafer is the micro / nano structure that is to be manufactured.

[0064] Therefore, refer to Figure 1 This can improve contact lithography equipment, for example by using a mask holder 101 to achieve proximity lithography.

[0065] The principle is as follows:

[0066] Three spacers 103 (serving as isolation, acting as a medium for contact between the mask and the wafer; i.e., levers) are added to the edge of the mask holder in the proximity lithography apparatus. The levers can switch between two states, such as... Figure 1 and Figure 2 As shown.

[0067] During exposure alignment, the three spacers can rotate to the position of exposure window 102 and are sandwiched between the sample and the photomask. Small balls 1031 are positioned at the ends of the spacers (away from the center of rotation), and these balls contact the sample below and the photomask above, respectively. After the contact action is completed, the stage (used to hold the wafer) descends, and the three spacers rotate back to their initial positions. Then, the stage rises again to the gap position set in the recipe for exposure.

[0068] The current equipment is mainly suitable for 4-inch wafers and cannot be used for proximity lithography processes on 2-inch wafers. Therefore, in the example of this application, lithography on 2-inch wafers can be achieved using the provided solution without any modifications to the equipment.

[0069] Specifically, in the example, this application discloses a mold that can be used as described above. Figure 1 It is used based on the structure and can achieve proximity lithography.

[0070] This mold can be used to achieve proximity lithography on wafers.

[0071] Furthermore, see Figure 3 The mold 400 includes a first plate 401 and a second plate 402 facing each other. Figure 3 Figure I and Figure II are structural schematic diagrams from two different perspectives. Figure III is a cross-sectional structural schematic diagram from another perspective.

[0072] When using the mold 400 for photolithography, the small balls 1031 of the above-mentioned paddles contact the first plate 401 and the mask respectively, so that the wafer and the mask are close to the design distance (related to the gap position).

[0073] The two plates can be fabricated using wafers or other substrates. Specifically, the first plate may be made of silicon in some examples, and the second plate may also be made of silicon in some examples. The first and second plates can be made of the same or different materials, and their selection can be independent without particular limitation.

[0074] The first plate defines a wafer fixing region, and the fixing region has vent holes 4011 extending along the thickness direction. Based on this, the wafer can be adsorbed and fixed on the first plate 401 by vacuum adsorption.

[0075] The vent is a cylindrical structure. Alternatively, the vent may be a plurality of cylindrical holes, all evenly distributed such that the axial distance between any two adjacent vents is the same. In other examples, the vent can also be other structural forms; for example, prism holes, more specifically hexagonal prism holes, etc. The cross-sectional area of ​​the hole (e.g., the area of ​​the base circle of a cylindrical hole) can be determined based on the adsorption effect, for example, to meet the vacuum requirements of the equipment for adsorbing wafers.

[0076] Furthermore, since the surface flatness can affect the adhesion and fixation of the wafer to be photolithographically etched in the mold, the surface of the first plate that comes into contact with the wafer to be photolithographically etched can be polished and planarized.

[0077] Planarization removes irregularities and height variations on the wafer surface, creating a uniform and flat surface. This has positive implications for subsequent processes in micro / nano fabrication, such as etching and thin film deposition, thereby improving chip performance, yield, and reliability. Exemplary planarization processes include Chemical Mechanical Polishing (CMP) and Etch Back (EB).

[0078] Chemical mechanical polishing (CMP) combines chemical etching and mechanical abrasion, using polishing pads and chemical polishing fluids to planarize the wafer surface. Etching back involves removing a portion of the material through etching to achieve specific structural or morphological requirements; it can be used to adjust film thickness, improve interlayer flatness, or form specific patterned structures.

[0079] The second plate 402 is opposite to the first plate 401, and the second plate 402 is provided with a placement hole 4021 for the wafer to pass through and be in face-to-face contact with the first plate. In the thickness direction of the opposing first and second plates, the placement hole is opposite to the fixing area.

[0080] The first and second plates can be fixedly connected or detachably connected. A fixed connection can be achieved by linking the two structures using a structure such as studs. A detachable connection can be achieved by bonding the first and second plates together, or by clamping and securing them using a fixture.

[0081] Since the alignment or bonding tightness and uniformity of the first plate 401 and the second plate 402 can affect the photolithography effect of the thickness, a pre-fabricated adhesive gasket, or adhesive layer 403, can be provided to improve the bonding of the two plates. The distance between the first and second plates can be controlled by precisely controlling the structure (thickness) of the gasket.

[0082] In other examples, the first plate and the second plate can also be fixed separately by configuring other components.

[0083] The above discussion covered the connection methods between the first and second plates. In other examples, to facilitate wafer positioning, one or both of the first and second plates can also be equipped with positioning structures. Therefore, when adsorbing and fixing the wafer, the wafer can be positioned based on the positioning structure, and then when using the mold, the orientation and position of the mold can be adjusted based on the positioning structure on the mold.

[0084] The positioning structure can be a rough portion, protrusion, or recess on the surface of the plate, etc. Exemplarily, in some examples, the positioning structure is a blind hole or a through hole. These positioning structures can be positioned relative to the placement hole. In some examples, the positioning structure can be configured adjacent to the placement hole, or it can be configured away from the placement hole. In the examples of this application, such as... Figure 4 As shown, in the second plate 402a, the hole wall of the hole-shaped (generally rectangular) positioning structure 4022 is connected to the hole wall of the placement hole 102.

[0085] The above-mentioned positioning structures, placement holes, and vent holes can be manufactured by combining photolithography and etching.

[0086] The etching process involves removing one or more materials. Depending on the material to be removed, the removal process may include, but is not limited to, wet etching or dry etching techniques. Known lithographic techniques (e.g., ultraviolet light or electron beam lithography) can be used to pattern the photoresist during the process.

[0087] Based on the above-described mold, a photolithography apparatus is also disclosed in this example. This photolithography apparatus includes the aforementioned mold. Furthermore, in some examples, the photolithography apparatus also includes a mask holder, a pick, and a worktable.

[0088] The mask holder has an exposure window. The lever is rotatable and connected to the mask holder. The plane of rotation of the lever is parallel to the plane of the mask holder (i.e., the plane of the mask, or the plane of the wafer).

[0089] The rotatable lever can move between the exposure window area and the non-exposure area by rotation. Specifically, in the non-working state (no photolithography), the lever retracts to the non-exposure area; in the working state (photolithography), the lever rotates out to the exposure area, i.e., the aforementioned exposure window. The lever in the exposure window area is used to contact the first plate in the mold and the photomask on its two surfaces in the thickness direction, respectively. The worktable is positioned opposite the photomask holder to fix the mold.

[0090] Furthermore, a lithography device may also include a housing, a mask assembly, a light source assembly, an optical path assembly, and a stage.

[0091] The enclosure is used to house various components.

[0092] For example, a light source assembly is located at the top of the enclosure to generate the light source for photolithography. The wavelength of this light source is, for example, any one of 436 nm, 365 nm, and 405 nm. This is ultraviolet (UV) lithography. It uses ultraviolet light with a wavelength range of approximately 365-436 nanometers, such as the I-line (365 nm), H-line (405 nm), and G-line (436 nm) emitted by a mercury lamp. Furthermore, deep ultraviolet (DUV) lithography can also be used. This uses a KrF excimer laser with a wavelength of 248 nanometers. Its lithographic resolution is significantly improved. Alternatively, an ArF excimer laser with a wavelength reaching 193 nanometers can be used.

[0093] A light path assembly is located vertically below the light source assembly to constrain and guide light along the executed optical path to the exposure window, so as to illuminate the wafer surface to be lithographically etched through the light-transmitting portion of the mask. The light path assembly may include a lens group consisting of multiple lenses—for example, it may include a reflector, an ellipsoidal mirror, a parabolic mirror, a lens group, and diffractive optical devices. For example, the light path assembly includes a light shield and a lens. The light shield is fixed to the housing, and a convex lens is disposed at the bottom of the light shield. Furthermore, the convex lens is positioned below the light source assembly, and the mask assembly is located below the convex lens.

[0094] The box also houses a mask assembly located below the optical path system, with a stage positioned below the mask assembly.

[0095] The embodiments described above with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0096] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, one or more embodiments have been described above with reference to the accompanying drawings. Throughout the description, similar reference numerals are used to denote similar components. In the foregoing description, numerous specific details have been set forth for illustrative purposes in order to provide a more thorough understanding of one or more embodiments. However, it will be apparent that one or more embodiments may be practiced in various circumstances without these specific details, and the embodiments may be combined with and referenced to each other without contradiction.

[0097] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0098] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion, such that a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0099] The above description of the structure, features and effects of this application is based on the embodiments shown in the drawings. The above are only preferred embodiments of this application. However, this application does not limit the scope of implementation to what is shown in the drawings. Any changes made in accordance with the concept of this application, or modifications to equivalent embodiments, that do not exceed the spirit covered by the specification and drawings, should be within the protection scope of this application.

Claims

1. A mold for realizing proximity lithography on wafers, characterized in that, The mold includes: A first plate is defined with a wafer fixing region, wherein the fixing region has vents extending in the thickness direction; The second plate, which is opposite to the first plate, is provided with placement holes for the wafer to pass through and to be in face-to-face contact with the first plate; In the thickness direction, the placement hole is opposite to the fixing area.

2. The mold according to claim 1, characterized in that, The vent hole has a cylindrical structure; Alternatively, the vent is a cylindrical hole, and there are multiple cylindrical holes, all of which are evenly distributed in such a way that the distance between the axes of any two adjacent vents is the same.

3. The mold according to claim 1, characterized in that, The first plate and the second plate are detachably connected.

4. The mold according to claim 1 or 3, characterized in that, The first plate is bonded to the second plate.

5. The mold according to claim 1, characterized in that, The first plate is made of silicon wafer; and / or the second plate is made of silicon wafer.

6. The mold according to claim 1, characterized in that, One or both of the first plate and the second plate are provided with a positioning structure.

7. The mold according to claim 6, characterized in that, The positioning structure is a blind hole or a through hole.

8. The mold according to claim 7, characterized in that, The hole wall of the positioning structure is connected to the hole wall of the placement hole.

9. A photolithography apparatus, characterized in that, The mold includes any one of claims 1 to 8.

10. The photolithography apparatus according to claim 9, characterized in that, Photolithography equipment also includes: Mask holder with an exposure window; A rotatable lever connected to the mask holder can be rotated to move between the exposure window area and the non-exposure area; and The worktable opposite the mask holder; The worktable is used to fix the mold, and the paddle located in the exposure window area is used to contact the mask and the first plate in the mold respectively on the two surfaces in the thickness direction.

Images