Wafer carrying device and wafer carrying method

Abstract

The application discloses a wafer bearing device and a wafer bearing method, which places the wafer to be bonded on the bearing, uses the pressure difference to apply uniform pressure on the wafer to make it closely adhere to the bearing, and avoids any tool or liquid from contacting and polluting the wafer surface to be bonded. The application solves the problem that the full-automatic ultrahigh vacuum bonding equipment is not easy to process various sizes of wafers to be bonded, ensures the cleanliness of the wafer surface to be bonded, and improves the bonding quality and reliability.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing technology, specifically relating to a wafer carrier device and wafer carrier method, which is particularly suitable for small-sized wafers (such as 4-inch or 6-inch wafers) bonded in ultra-high vacuum bonding. Background Technology

[0002] Ultra-high vacuum bonding is a wafer bonding technique performed in an ultra-high vacuum (UHV) environment. Surface activation direct bonding, in particular, cleans the wafer surface using activation methods such as argon ion beams to achieve direct bonding at room temperature or low temperature. Ultra-high vacuum bonding requires extremely high cleanliness of the wafer surface; any contamination will lead to bonding failure or a decrease in bonding quality.

[0003] Existing ultra-high vacuum bonding equipment is typically designed to process standard-sized wafers, such as 8-inch or 12-inch wafers. However, in practical applications, it is often necessary to bond smaller wafers (such as 4-inch or 6-inch wafers) to standard-sized wafers, or to form bonds between smaller wafers. Because bonding equipment typically uses an up-and-down bonding head structure, one of the wafers needs to be inverted and fixed. Therefore, the smaller wafer must be reliably fixed to a carrier wafer in order to be processed by the standard equipment.

[0004] In the prior art, methods for fixing small-sized wafers to carrier wafers include: first, using clamps or mechanical fixing devices, but this method will contact and contaminate the bonding surface of the small-sized wafer; second, using single-sided or double-sided films or tapes for fixing, but this method is cumbersome to operate; common tapes have serious gas release in vacuum, and will soften, deform and temporarily lose their adhesiveness during the sputtering deposition process in the coating station integrated with the bonding equipment.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a wafer carrier device and a wafer carrier method, which can reliably fix the wafer to the carrier without contacting the surface of the wafer to be bonded.

[0007] To achieve the above objectives, a specific embodiment of the present invention provides the following technical solution:

[0008] A wafer carrier device, comprising:

[0009] The differential pressure chamber includes a first chamber, the first chamber having a first bearing surface, and a hole communicating with the first chamber is provided on the first bearing surface;

[0010] A carrier is detachably mounted on the first carrier surface. The carrier has vent holes extending through its thickness direction. Some or all of the vent holes are exposed by the holes. The first chamber is connected to the vent holes through the holes. The carrier has a second carrier surface for placing a wafer. When the wafer is placed on the second carrier surface, the wafer covers the vent holes, thereby isolating the first chamber from the air passage.

[0011] The first chamber is configured to controllably introduce pressurized gas to create a pressure difference between the upper and lower sides of the carrier, pressing the wafer against the second carrier surface.

[0012] In one or more embodiments of the present invention, an adhesive layer is provided on the second bearing surface of the bearing member.

[0013] In one or more embodiments of the present invention, the material of the adhesive layer is selected from low-outgas vacuum grease, wherein the low-outgas vacuum grease has an outgassing rate of less than 10% under vacuum conditions. -5 mbar·L / (s·cm 2 ).

[0014] In one or more embodiments of the present invention, the second bearing surface of the carrier has a first region located at the center of the carrier and a second region coaxially surrounding the first region, wherein when the wafer is placed on the second bearing surface, the orthographic projection of the wafer covers the first region.

[0015] In one or more embodiments of the present invention, the vent is located within the first region; and / or,

[0016] Multiple ventilation holes are arranged in an array at equal intervals within the first region.

[0017] In one or more embodiments of the present invention, the wafer carrier further includes a pressure application unit connected to the first chamber, the pressure application unit being configured to controllably apply pressure to the first chamber to generate a pressure difference acting on the wafer and the carrier.

[0018] In one or more embodiments of the present invention, the differential pressure chamber further includes a second chamber located above the first chamber. The second chamber is connected to the first chamber via a vent hole in the carrier and a hole in the first carrier surface. When the wafer is placed on the second carrier surface of the carrier, the wafer covers the vent hole, thereby isolating the second chamber from the first chamber's air passage.

[0019] In one or more embodiments of the present invention, the second chamber is connected to the pressure application unit, and the second chamber is configured to controllably and independently introduce pressurized gas to generate a pressure difference different from the pressure of the first chamber when the wafer covers the vent hole, thereby pressing the wafer against the second support surface by forming a pressure difference on the upper and lower sides of the support member.

[0020] In one or more embodiments of the present invention, the pressure application unit is configured to selectively generate a first differential pressure mode, a second differential pressure mode, or a third differential pressure mode;

[0021] In the first differential pressure mode, the second chamber is under atmospheric pressure, and the vacuum level of the first chamber reaches a preset value. Pressure is applied to the wafer by utilizing the pressure difference between atmospheric pressure and vacuum.

[0022] In the second differential pressure mode, the second chamber is in a high-pressure state with a pressure higher than atmospheric pressure, while the first chamber is in an atmospheric pressure state. The pressure difference between the high pressure and atmospheric pressure is used to apply pressure to the wafer.

[0023] In the third differential pressure mode, the second chamber is in a high-pressure state with a pressure higher than atmospheric pressure, and the vacuum degree of the first chamber reaches a preset value. Pressure is applied to the wafer by utilizing the pressure difference between the high pressure and the vacuum.

[0024] A wafer carrier method, comprising:

[0025] Provide the aforementioned wafer carrier device;

[0026] An adhesive is applied to the second bearing surface of the bearing member to form an adhesive layer;

[0027] The wafer is placed on the adhesive layer to form an assembly, and then placed on the first support surface. The vent hole of the support is connected to the first chamber through the hole.

[0028] Pressure is applied to the first chamber to generate a pressure difference, which acts on the wafer through the vent hole, causing the wafer to fit tightly against the carrier.

[0029] In one or more embodiments of the present invention, the adhesive is applied to the second bearing surface of the bearing member using a serrated scraper to form an adhesive layer with a toothed texture, wherein the height of the toothed texture of the adhesive layer is less than 10 μm and the tooth spacing is less than 10 μm.

[0030] In one or more embodiments of the present invention, the wafer carrier method further includes applying pressure to the second chamber to generate a pressure difference different from that of the first chamber, acting on the wafer to make the wafer fit tightly against the carrier.

[0031] In one or more embodiments of the present invention, pressurizing the first chamber and the second chamber respectively to generate a pressure difference includes:

[0032] When the target pressure value is lower than the preset threshold, the first pressure difference mode is adopted: maintain the atmospheric pressure state in the second chamber, perform vacuum treatment on the first chamber to make its vacuum degree reach the preset value, and apply pressure to the wafer by utilizing the pressure difference formed between the atmospheric pressure and the vacuum state of the first chamber;

[0033] When the target pressure value is higher than a preset threshold, a second pressure difference mode or a third pressure difference mode is adopted: high-pressure gas is introduced into the second chamber to maintain the atmospheric pressure state in the first chamber, and pressure is applied to the wafer by using the pressure difference between the high-pressure gas and the atmospheric pressure; or, high-pressure gas is introduced into the second chamber to evacuate the first chamber to achieve a preset vacuum level, and pressure is applied to the wafer by using the pressure difference between the high-pressure gas and the vacuum state of the first chamber.

[0034] The preset threshold range is 0.1 MPa to 0.8 MPa.

[0035] In one or more embodiments of the present invention, the wafer carrying method further includes simultaneously vacuuming the first chamber and the second chamber before or after the pressure application process to remove or stabilize air bubbles embedded in the adhesive layer.

[0036] Compared with existing technologies, the wafer carrier device and method of the present invention, by controlling the pressure of different chambers, create a pressure difference on the upper and lower sides of the carrier, thereby pressing and fixing the wafer onto the carrier. No tools or liquids come into contact with the wafer's bonding surface (front side) throughout the entire process, maximizing surface cleanliness and meeting the stringent surface quality requirements of ultra-high vacuum bonding. The entire fixing process is carried out under normal pressure or controlled atmospheric pressure, eliminating the need for heating or complex mechanical operations, thus simplifying the process flow.

[0037] The wafer carrier device and wafer carrier method of the present invention can adapt to wafers with different viscosity adhesive layers and different surface conditions by selecting different pressure difference modes, thus ensuring reliable bonding.

[0038] The wafer carrier device and wafer carrier method of the present invention can effectively remove or stabilize bubbles embedded in the adhesive layer through vacuum treatment, prevent bubbles from bursting and causing contamination in the high vacuum bonding chamber, and improve bonding success and bonding quality; the adhesive layer material is a conventional material that can be reused, reducing production costs.

[0039] The wafer carrier device and wafer carrier method of the present invention use a standard size (such as 12 inches) carrier, which can directly use existing bonding equipment to process small-sized wafers (such as 4 inches or 6 inches) without the need for equipment modification. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic cross-sectional view of the wafer carrier device in Embodiment 1 of the present invention;

[0042] Figure 2 This is a top view schematic diagram showing the positional relationship between the carrier component and the wafer (dashed line) in Embodiment 1 of the present invention;

[0043] Figure 3 This is a schematic diagram of the scraper tool used when carrying a wafer using the wafer carrier device in Embodiment 1 of the present invention;

[0044] Figure 4 This is a schematic cross-sectional view of the wafer carrier device in Embodiment 2 of the present invention;

[0045] Figure 5 This is a schematic diagram showing the positional relationship between the carrier component and the wafer in Embodiment 2 of the present invention. Detailed Implementation

[0046] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0047] As mentioned in the background section, current methods for fixing small-sized wafers to carrier wafers mainly include: using clamps or mechanical fixing devices, which directly contact and contaminate the surface to be bonded; using single-sided or double-sided films or tapes, which are cumbersome to operate; and ordinary tapes are prone to severe gas release in a vacuum and are easily softened, deformed, and temporarily lose their adhesiveness when sputtered and deposited at the coating station integrated in the bonding equipment.

[0048] In addition, when using adhesive materials to temporarily fix the wafer, air bubbles are inevitably embedded during the wafer placement process. These bubbles may burst in the ultra-high vacuum bonding chamber, causing gas and adhesive to splash and seriously contaminate the chamber and the wafer surface.

[0049] Based on this, the present invention provides a wafer carrier device and a wafer carrier method. By applying different pressures in different chambers, a pressure difference is created on the upper and lower sides of the carrier, pressing and fixing the wafer onto the carrier. Throughout the process, no tools or liquids come into contact with the wafer's bonding surface, maximizing surface cleanliness and meeting the stringent surface quality requirements of ultra-high vacuum bonding. The entire fixing process is performed under normal pressure or controlled atmospheric pressure, eliminating the need for heating or complex mechanical operations, thus simplifying the process flow. Simultaneously, the vacuum treatment effectively removes or stabilizes air bubbles embedded in the adhesive layer, preventing bubble bursts and contamination in the high-vacuum bonding chamber, thereby improving bonding success rate and bonding quality.

[0050] The wafer carrier device of the present invention specifically includes the following components:

[0051] The carrier has a size compatible with standard bonding equipment (e.g., 12 inches). The carrier has a second carrier surface for placing the wafer, with a first region located at the center of the carrier and a second region coaxially surrounding the first region. When the wafer is placed on the second carrier surface, the orthographic projection of the wafer covers the first region.

[0052] The carrier has one or more vent holes extending through its thickness direction, preferably multiple vent holes. The vent holes are located in a first region, and preferably, multiple vent holes are arranged in an array at equal intervals within the first region. When the wafer is placed on the second bearing surface of the carrier, the wafer covers all the vent holes.

[0053] An adhesive can be applied to the second bearing surface of the carrier to form an adhesive layer. Preferably, the adhesive is applied to the first region of the second bearing surface of the carrier for sealing and temporary fixation of the wafer. The adhesive can be a medium material with a certain viscosity and low outgassing characteristics, such as a low-outgassing vacuum grease, whose outgassing rate in a vacuum environment is less than 10%. -5 mbar·L / (s·cm 2 ).

[0054] The carrier can be made of silicon wafers, or, depending on the type of chuck in the bonding equipment and the process type, ceramic or metal disks, as well as ceramic or metal disks with silicon coatings on their surfaces. The wafer can be a 2, 3, 4, 5, or 6-inch wafer that is smaller than the size of the bonding equipment head and conforms to international standards, or an irregularly shaped wafer that does not conform to standard dimensions.

[0055] The differential pressure chamber may consist only of a first chamber, or it may include a second chamber and a first chamber distributed vertically. The first chamber has a first bearing surface, and the second chamber and the first chamber can be divided by the first bearing surface. For example, the first bearing surface may be the upper surface of a bearing platform disposed within the differential pressure chamber. The bearing platform may be fixedly disposed within the differential pressure chamber to divide the first chamber and the second chamber, or the bearing platform may be detachably disposed within the differential pressure chamber and sealed by a sealing ring, thereby dividing the first chamber and the second chamber.

[0056] The first bearing surface has holes that connect to the first chamber. The holes can partially or completely expose the vents on the bearing. Preferably, the holes and vents on the bearing are arranged in a one-to-one correspondence. When the bearing is placed on the first bearing surface, the vents and holes are aligned to form a gas passage.

[0057] The pressure application unit, used to generate a pressure difference within the pressure differential chamber, can be connected only to the first chamber or to both the first and second chambers. It is configured to controllably apply pressure to the first chamber or controllably apply pressure to both chambers to generate a pressure difference acting on the wafer and the carrier. Pressure is applied to the wafer toward the carrier through a vent. The pressure application unit can be a manual pressure application device or a fully automatic electric pressure application device.

[0058] The pressure application unit is configured to selectively generate a first differential pressure mode, a second differential pressure mode, or a third differential pressure mode. Wherein:

[0059] In the first differential pressure mode, the second chamber is under atmospheric pressure, or when the second chamber is not set, the second bearing surface of the carrier is exposed to the external atmospheric environment, the vacuum degree of the first chamber reaches the preset value and is in a vacuum state, and the pressure difference between atmospheric pressure and vacuum is used to apply pressure to the wafer, which is suitable for occasions that require lower pressure.

[0060] In the second differential pressure mode, the second chamber is in a high-pressure state with a pressure higher than atmospheric pressure. For example, high-pressure gas (filtered high-purity nitrogen, with a pressure of up to 1 MPa) is injected into the second chamber, while the first chamber is in an atmospheric pressure state. The pressure difference between the high pressure and atmospheric pressure is used to apply pressure to the wafer, which is suitable for occasions that require greater pressure.

[0061] In the third differential pressure mode, the second chamber is in a high-pressure state with a pressure higher than atmospheric pressure. For example, high-pressure gas (filtered high-purity nitrogen, with a pressure of up to 1 MPa) is injected into the second chamber, and the vacuum degree of the first chamber reaches the preset value and is in a vacuum state. The pressure difference between the high pressure and the vacuum is used to apply pressure to the wafer.

[0062] High-pressure gases can also be inert gases commonly used in semiconductor processes and readily available in semiconductor facilities, such as ordinary nitrogen, high-purity nitrogen, argon, and helium, with relative pressures between 0 MPa and 30 MPa.

[0063] The differential pressure chamber can also be connected to a vacuum pumping unit to perform long-term vacuuming of the chamber, removing or stabilizing air bubbles embedded in the adhesive layer. Vacuuming allows small bubbles to diffuse out or stabilizes large bubbles to prevent them from bursting in subsequent high-vacuum environments.

[0064] The present invention also provides a wafer carrier method, comprising the following steps:

[0065] S1 provides the aforementioned wafer carrier device.

[0066] S2, an adhesive is applied to the second bearing surface of the bearing to form an adhesive layer.

[0067] S3, the wafer is placed on the adhesive layer to form an assembly, and then placed on the first carrier surface. The vent hole of the carrier is connected to the first chamber through the hole.

[0068] S4 applies pressure to the first chamber to generate a pressure difference, which acts on the wafer through the vent hole, making the wafer fit tightly against the carrier.

[0069] In step S2, an adhesive is applied using a serrated scraper to form an adhesive layer with a serrated texture. The height of the serrated texture of the adhesive layer is less than 10 μm, and the spacing is less than 10 μm. The amount of adhesive applied is determined based on the wafer size and the viscosity of the adhesive to ensure uniform coverage of the wafer's projected area without over-application.

[0070] In step S4, pressure can be applied to the second chamber to create a pressure difference different from that of the first chamber, which is then applied to the wafer through the vent to ensure a tight fit between the wafer and the carrier. Throughout the process, no tools or liquids come into contact with the wafer's bonding surface, ensuring surface cleanliness.

[0071] Preferably, depending on the required pressure, a first differential pressure mode, a second differential pressure mode, or a third differential pressure mode can be selected. When the target pressure value is lower than a preset threshold, the first differential pressure mode is used: maintaining the atmospheric pressure state in the second chamber, evacuating the first chamber to achieve a preset vacuum level, and applying pressure to the wafer using the pressure difference between atmospheric pressure (approximately 0.1 MPa) and the vacuum state of the first chamber (e.g., 1 Pa), which can generate a uniform pressure of approximately 0.1 MPa.

[0072] When the target pressure value exceeds a preset threshold, a second or third differential pressure mode is adopted: high-pressure gas is introduced into the second chamber to maintain the atmospheric pressure state in the first chamber, and pressure is applied to the wafer using the pressure difference between the high-pressure gas and atmospheric pressure; or, high-pressure gas is introduced into the second chamber to evacuate the first chamber to achieve a preset vacuum level, and pressure is applied to the wafer using the pressure difference between the high-pressure gas and the vacuum state of the first chamber; the preset threshold range is 0.1 MPa to 0.8 MPa.

[0073] The second differential pressure mode utilizes the pressure difference between a high-pressure gas (such as 1 MPa nitrogen) and the external gas pressure to generate a higher pressure of approximately 0.9 MPa. The third differential pressure mode utilizes the pressure difference between a high-pressure gas (such as 1 MPa argon) and a vacuum (such as 1 Pa) to generate an even higher pressure of approximately 1 MPa. For small-sized wafers (such as 6 inches), the pressure generated by the differential pressure is proportional to the wafer area, and a 1 MPa differential pressure can generate a pressure not exceeding 17.7 kN.

[0074] Preferably, the differential pressure chamber can be subjected to a prolonged vacuum treatment before or after the pressurization process to remove or stabilize air bubbles embedded in the adhesive layer. The vacuuming time is determined based on the bubble size and the characteristics of the adhesive, typically ranging from 10 minutes to 2 hours, with a vacuum level better than 10. -2 Pa. Prolonged vacuuming can allow small bubbles to diffuse to the edge and be discharged through vacuum grease, or partially extract the gas inside large bubbles, reducing the internal pressure of the bubbles and preventing them from escaping into the subsequent high-vacuum bonding chamber, damaging the vacuum level, or bursting and splashing to contaminate the high-vacuum chamber.

[0075] After the above treatment, the wafer is temporarily fixed to the carrier by the adhesive layer, forming a reliable bonding pair. This bonding pair can be placed upside down into the ultra-high vacuum bonding equipment. The wafer remains fixed under the combined action of gravity and the adhesive force of the adhesive, and will not fall off during the flipping, transporting, and clamping processes with the wafer face down. After entering the bonding chamber of the bonding equipment, the low outgassing characteristics of the adhesive ensure that the vacuum level of the chamber will not be disrupted. At the same time, embedded air bubbles have been stabilized and will not escape or burst in the ultra-high vacuum environment, causing contamination.

[0076] Compared with existing technologies, the wafer carrier device and method of the present invention, by controlling the pressure of different chambers, create a pressure difference on the upper and lower sides of the carrier, thereby pressing and fixing the wafer onto the carrier. No tools or liquids come into contact with the wafer's bonding surface throughout the entire process, maximizing surface cleanliness and meeting the stringent surface quality requirements of ultra-high vacuum bonding. The entire fixing process is carried out under normal pressure or controlled atmospheric pressure, eliminating the need for heating or complex mechanical operations, thus simplifying the process flow.

[0077] The wafer carrier device and wafer carrier method of the present invention can adapt to wafers with different viscosity adhesive layers and different surface conditions by selecting different pressure difference modes, thus ensuring reliable bonding.

[0078] The wafer carrier device and wafer carrier method of the present invention can effectively remove or stabilize bubbles embedded in the adhesive layer through vacuum treatment, prevent bubbles from bursting and causing contamination in the high vacuum bonding chamber, and improve bonding success and bonding quality; the adhesive layer material is a conventional material that can be reused, reducing production costs.

[0079] The wafer carrier device and wafer carrier method of the present invention use a standard size (such as 12 inches) carrier, which can directly use existing bonding equipment to process small-sized wafers (such as 4 inches or 6 inches) without the need for equipment modification.

[0080] The technical solution of the present invention will be described in detail below through two specific embodiments.

[0081] Example 1: Using the first differential pressure mode, a 4-inch wafer is fixed on a 6-inch carrier wafer (carrier).

[0082] like Figure 1 and Figure 2 As shown, the wafer carrier device in this embodiment includes a carrier wafer 204, an adhesive layer 205, a small-sized wafer 206, a first chamber 202, and a pressure application unit. The pressure application unit includes a switching hand valve 210 and a vacuum pump 209. The entire wafer carrier device operates in atmospheric environment 201.

[0083] The carrier wafer 204 is a 6-inch silicon wafer with a thickness of 725 μm. Vent holes 207, each 1 mm in diameter, are distributed on the upper surface of the carrier wafer 204, with a maximum spacing of 15 mm, and are uniformly distributed in an array. The vent holes 207 penetrate the carrier wafer 204 and are only distributed in a first region 211 with a diameter of 100 mm at the center of the carrier wafer 204, corresponding to the position where a 4-inch wafer is placed.

[0084] Dow HVG series vacuum silicone grease is applied as a temporary adhesive within the first region 211 at the center of the upper surface of the carrier wafer 204, with an outgassing rate of less than 10%. -9 Torr·L / (s·cm 2 ).

[0085] Specifically, using Figure 3The scraper 301 shown is used to spin-coat and spread the adhesive evenly. The scraper 301 is made of silicon wafer by laser cutting, and its bottom 302 is serrated. The serrations of the scraper 301 are only distributed in the central area with a length of 100 mm, the tooth depth 304 is 10 μm, and the tooth spacing 303 is 10 μm. Using the scraper 301 to apply the adhesive can form an adhesive layer 205 with a height of less than 10 μm and a concentric circle texture, which facilitates the subsequent contact between the small-sized wafer 206 and the adhesive layer 205 and the expulsion of gas between them.

[0086] A small wafer 206 (4-inch indium phosphide substrate, 625 μm thick) is placed on the bonding layer 205 with the bonding surface 212 of the small wafer 206 facing upwards. During placement, a certain amount of air bubbles will be embedded in the bonding layer 205, which will be removed during subsequent vacuuming.

[0087] An assembly of a carrier wafer 204 and a small-sized wafer 206 is placed on the upper surface 203 of the first chamber 202. The upper surface 203 of the first chamber 202 has holes 208 that match the vent holes 207 of the carrier wafer 204. The carrier wafer 204 is placed on the upper surface 203 of the first chamber 202, with the vent holes 207 aligned with the holes 208 of the first chamber 202.

[0088] The first differential pressure mode is adopted: the oil-free vacuum pump 209 is turned on and the switching hand valve 210 is opened to evacuate the first chamber 202 to approximately 0.5 Pa. At this time, the atmospheric pressure acting on the upper surface 212 of the small-sized wafer 206 is approximately 0.1 MPa, while the first chamber 202 is in a vacuum state. Therefore, the pressure acting on the lower surface of the small-sized wafer 206 through the holes 208 and the vent 207 is almost 0. The resulting pressure difference of approximately 0.1 MPa presses the small-sized wafer 206 evenly against the carrier wafer 204, causing the adhesive layer 205 to spread evenly. Air bubbles in the adhesive layer 205 enter the first chamber 202 through the vent 207 and the holes 208. Excess adhesive is squeezed into the vent 207 or squeezed out of the area between the small-sized wafer 206 and the carrier wafer 204, achieving a tight and flat bonding between the two.

[0089] After maintaining the pressure difference for 30 minutes, turn off the vacuum pump 209 and close the switching hand valve 210 to allow atmospheric air to enter the first chamber 202. At this time, the small-sized wafer 206 has been firmly adhered to the carrier wafer 204 through the adhesive layer 205.

[0090] After the above processing, the small-size wafer 206 is reliably fixed onto the carrier wafer 204. The bonding pair is then fed into the wafer carrier of a fully automated bonding equipment for bonding. In the vacuum environment of the automated equipment, even with the front side 212 facing down, the adhesion force of the adhesive layer 205 keeps the small-size wafer 206 fixed and prevents it from detaching. Simultaneously, the adhesive layer 205 is selected with an outgassing rate of less than 10%. -9 Torr·L / (s·cm 2 Vacuum silicone grease, the bonding pairs will not be damaged, which is superior to 10. -8 The ultra-high vacuum chamber state is measured in mbar. Due to the 10-minute vacuum negative pressure treatment, the embedded air bubbles in the adhesive layer 205 have been stabilized and will not burst or release gas in the ultra-high vacuum environment, thus preventing contamination of the bonding environment.

[0091] Example 2: Using the third differential pressure mode, a 6-inch alumina wafer is fixed on an 8-inch carrier wafer (carrier).

[0092] like Figure 4 As shown, the wafer carrier device in this embodiment includes a wafer carrier 405, an adhesive layer 404, a small-size wafer 403, a first chamber 402, a second chamber 401, and a pressure application unit. The pressure application unit in this embodiment is a fully automatic electric device. The host computer 415, through a programmable logic controller (PLC) 416, acquires signals from a vacuum gauge 408 and controls the on / off states of solenoid valves 409, 410, 411, and 412 to achieve automatic bonding control.

[0093] To increase the number of reuses and reduce costs, this embodiment uses a metal carrier wafer 405. The bonding equipment applicable to this embodiment activates the surface of a small-sized wafer using an argon atomic beam. Therefore, to prevent metal from being sputtered onto the surface of the small-sized wafer 403 during activation and causing contamination, the metal surface of the carrier wafer 405 in this embodiment is also coated with a 1 μm thick layer of polycrystalline silicon material. Figure 4 (Not shown in the image).

[0094] In this embodiment, the wafer carrier device is adapted to accommodate small-sized wafers 403 and carrier wafers 405 of different sizes, as well as their vent hole distributions. A replaceable carrier platform 406 supports the carrier wafer 405. The carrier platform 406 divides the pressure differential chamber into a second chamber 401 and a first chamber 402 via a sealing ring 407. The carrier platform 406 has a hole pattern that matches the vent holes of the carrier wafer 405.

[0095] like Figure 5As shown, the carrier wafer 405 can be embedded in the carrier platform 406, and the vent holes and apertures of both are aligned. After coating the carrier wafer 405 with an adhesive layer 404 of uniform thickness with concentric circle texture, under normal pressure, a small wafer 403 is placed on the adhesive layer 404 using a tool such as a suction pen that does not need to touch the front of the wafer. Finally, the combination of the carrier wafer 405 and the small wafer 403 is placed on the carrier platform 406 (i.e., the first carrier surface).

[0096] The wafer carrier device in this embodiment is used in a similar manner to that in Embodiment 1, but employs a third differential pressure mode: the host computer sends a command to open solenoid valve 409 and close solenoid valve 410, injecting high-pressure (10 MPa) argon gas from argon cylinder 414 into the second chamber 401; solenoid valve 411 and vacuum pump 413 are opened, and solenoid valve 412 is closed, so that the vacuum degree of the first chamber 402 reaches approximately 1 Pa. The high-pressure argon gas acts on the front side of the small-sized wafer 403, while the gas pressure in the second chamber is almost 0, resulting in a differential pressure of approximately 10 MPa, which uniformly presses the small-sized wafer 403 onto the carrier wafer 405.

[0097] The third differential pressure mode can generate greater pressure than the first differential pressure mode, which is suitable for situations where the adhesive viscosity is high or the wafer surface requires greater pressure to achieve full adhesion. After maintaining the differential pressure for 5 minutes, the host computer 415 closes the solenoid valve 409 and opens the solenoid valve 410 via the PLC 416, slowly releasing the pressure in the second chamber 401 to atmospheric pressure; then, it closes the solenoid valve 411 and opens the solenoid valve 412, slowly raising the pressure in the first chamber 402 back to atmospheric pressure.

[0098] It is important to note that during the pressure release process, the pressure in the second chamber should be released to a level no higher than that in the first chamber before the first chamber is filled with gas, in order to prevent the wafer from being subjected to upward pressure and falling off.

[0099] To further eliminate any air bubbles that may be present in the adhesive layer 404, after the pressure in the second chamber 401 and the first chamber 402 returns to atmospheric pressure, the solenoid valves 410 and 411 are reopened to simultaneously evacuate both chambers to a vacuum better than 1 Pa for 1 hour. During this process, the air bubbles embedded in the adhesive layer 404 may undergo the following changes: for small air bubbles with smaller diameters, the internal gas diffuses to the edge through the adhesive and is gradually discharged; for medium-sized air bubbles, some of the internal gas is extracted, and the internal pressure of the air bubble decreases to balance with the external vacuum; for large air bubbles with larger diameters, the internal gas is significantly extracted, and the air bubble collapses or its internal pressure decreases dramatically.

[0100] This process stabilizes the air bubbles in the adhesive layer 404, preventing them from bursting in the ultra-high vacuum environment of the subsequent bonding chamber. Comparative experiments show that the sample after bubble removal eliminates random fluctuations in the vacuum level of the bonding chamber, shortens the bonding process time, and significantly improves the bonding yield.

[0101] This invention can be directly applied to ultra-high vacuum bonding processes in semiconductor manufacturing, and is particularly suitable for the following scenarios:

[0102] Composite substrate fabrication: A compound semiconductor substrate (such as GaAs or InP, typically 6 inches or 2 inches) is bonded to a silicon carbide substrate to form a composite substrate.

[0103] Heterogeneous integration manufacturing: bonding compound semiconductor wafers with device structures (such as GaAs and InP, typically 6 inches or 2 inches) onto silicon wafers to form interconnect wafers.

[0104] MEMS manufacturing: bonding small-sized MEMS wafers onto standard-sized packaged wafers.

[0105] The method of this invention can be seamlessly integrated with existing high-vacuum bonding equipment without requiring equipment modification, and has good industrial applicability.

[0106] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0107] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A wafer carrier device, characterized in that, include: The differential pressure chamber includes a first chamber, the first chamber having a first bearing surface, and a hole communicating with the first chamber is provided on the first bearing surface; A carrier is detachably mounted on the first carrier surface. The carrier has vent holes extending through its thickness direction. Some or all of the vent holes are exposed by the holes. The first chamber is connected to the vent holes through the holes. The carrier has a second carrier surface for placing a wafer. When the wafer is placed on the second carrier surface, the wafer covers the vent holes, thereby isolating the first chamber from the air passage. The first chamber is configured to controllably introduce pressurized gas to create a pressure difference between the upper and lower sides of the carrier, pressing the wafer against the second carrier surface.

2. The wafer carrier apparatus of claim 1, wherein, An adhesive layer is provided on the second bearing surface of the bearing member.

3. The wafer carrier apparatus of claim 2, wherein, The adhesive layer is made of a low-out-gas vacuum grease, which has an out-gas rate of less than 10% under vacuum conditions. -5 mbar·L / (s·cm 2 ).

4. The wafer carrier apparatus of claim 1, wherein, The second bearing surface of the carrier has a first region located at the center of the carrier, and a second region coaxially surrounding the first region. When the wafer is placed on the second bearing surface, the orthographic projection of the wafer covers the first region.

5. The wafer carrier apparatus of claim 4, wherein, The vent is located within the first region; and / or, Multiple ventilation holes are arranged in an array at equal intervals within the first region.

6. The wafer carrier device according to claim 1, characterized in that, The wafer carrier further includes a pressure application unit connected to the first chamber, the pressure application unit being configured to controllably apply pressure to the first chamber to generate a pressure difference acting on the wafer and the carrier.

7. The wafer carrier apparatus of claim 6, wherein, The differential pressure chamber also includes a second chamber located above the first chamber. The second chamber is connected to the first chamber via a vent hole in the carrier and a hole in the first carrier surface. When the wafer is placed on the second carrier surface of the carrier, the wafer covers the vent hole, thereby isolating the second chamber from the first chamber's air passage.

8. The wafer carrier apparatus of claim 7, wherein, The second chamber is connected to the pressure application unit and is configured to independently and controllably introduce pressurized gas to generate a pressure difference different from that of the first chamber when the wafer covers the vent hole. By forming a pressure difference on the upper and lower sides of the carrier, the wafer is pressed against the second carrier surface.

9. The wafer carrier apparatus of claim 7, wherein, The pressure application unit is configured to selectively generate a first differential pressure mode, a second differential pressure mode, or a third differential pressure mode; In the first differential pressure mode, the second chamber is under atmospheric pressure, and the vacuum level of the first chamber reaches a preset value. Pressure is applied to the wafer by utilizing the pressure difference between atmospheric pressure and vacuum. In the second differential pressure mode, the second chamber is in a high-pressure state with a pressure higher than atmospheric pressure, while the first chamber is in an atmospheric pressure state. The pressure difference between the high pressure and atmospheric pressure is used to apply pressure to the wafer. In the third differential pressure mode, the second chamber is in a high-pressure state with a pressure higher than atmospheric pressure, and the vacuum degree of the first chamber reaches a preset value. Pressure is applied to the wafer by utilizing the pressure difference between the high pressure and the vacuum.

10. A wafer carrying method characterized by comprising: include: Provide a wafer carrier device as described in any one of claims 1 to 9; An adhesive is applied to the second bearing surface of the bearing member to form an adhesive layer; The wafer is placed on the adhesive layer to form an assembly, and then placed on the first support surface. The vent hole of the support is connected to the first chamber through the hole. Pressure is applied to the first chamber to generate a pressure difference, which acts on the wafer through the vent hole, causing the wafer to fit tightly against the carrier.

11. The wafer carrying method according to claim 10, wherein, The adhesive is applied to the second bearing surface of the bearing member using a serrated scraper to form an adhesive layer with a toothed texture. The height of the toothed texture of the adhesive layer is less than 10 μm, and the tooth spacing is less than 10 μm.

12. The wafer carrier method according to claim 10, characterized in that, It also includes applying pressure to the second chamber to create a pressure difference different from that of the first chamber, acting on the wafer to make the wafer fit tightly against the carrier.

13. The wafer carrying method according to claim 12, wherein Applying pressure to the first chamber and the second chamber respectively to create a pressure difference includes: When the target pressure value is lower than the preset threshold, the first pressure difference mode is adopted: maintain the atmospheric pressure state in the second chamber, perform vacuum treatment on the first chamber to make its vacuum degree reach the preset value, and apply pressure to the wafer by utilizing the pressure difference formed between the atmospheric pressure and the vacuum state of the first chamber; When the target pressure value is higher than a preset threshold, a second pressure difference mode or a third pressure difference mode is adopted: high-pressure gas is introduced into the second chamber to maintain the atmospheric pressure state in the first chamber, and pressure is applied to the wafer by using the pressure difference between the high-pressure gas and the atmospheric pressure; or, high-pressure gas is introduced into the second chamber to evacuate the first chamber to achieve a preset vacuum level, and pressure is applied to the wafer by using the pressure difference between the high-pressure gas and the vacuum state of the first chamber. The preset threshold range is 0.1 MPa to 0.8 MPa.

14. The wafer carrying method of claim 12, wherein, It also includes simultaneously evacuating the first and second chambers before or after the pressurization process to remove or stabilize air bubbles embedded in the adhesive layer.

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