Plasma activation device and method for high-vacuum wafer bonding

Abstract

The invention relates to the technical field of high-vacuum wafer bonding, in particular to a plasma activation device and method for high-vacuum wafer bonding. In order to solve the problem that the existing plasma activation device still has certain limitations in the aspects of uniformity and activation efficiency, the invention provides a novel plasma activation device and method for high-vacuum wafer bonding, and the device comprises a square cavity shell, two scattering plates are arranged at the positions, corresponding to the upper air inlets, in the square cavity shell, upper air inlet holes in the two scattering plates are arranged in a staggered mode, an annular air inlet cavity communicated with the side air inlets is fixed in the square cavity shell, a plurality of side air inlet holes are distributed in the annular air inlet cavity, and during air exhaust, a molecular pump and a dry pump are matched for air exhaust. According to the device and the method, the uniformity of the plasma is effectively improved, so that the surface quality of the wafer is improved, and the bonding quality of the wafer is further improved.

Description

Technical Field

[0001] The invention relates to the technical field of high vacuum wafer bonding, and in particular to a plasma activation device and method for high vacuum wafer bonding. Background Art

[0002] Wafer bonding technology refers to the process of tightly bonding two mirror-polished homogeneous or heterogeneous wafers together through chemical and physical effects. After the wafers are bonded, the atoms on the interface react under the action of external forces to form covalent bonds to combine them into one, and the bonding interface reaches a specific bonding strength.

[0003] Plasma activation is an extremely important step in wafer bonding pretreatment, which is used to improve the physical and chemical properties of the wafer surface. It activates the wafer surface using plasma, making it easier for the wafer to bond with other wafers.

[0004] Existing plasma activation devices still have certain limitations in uniformity, activation efficiency and process flexibility. Especially when facing wafers with complex structures and large sizes, it is difficult to ensure the uniformity of plasma distribution and activation efficiency, which affects the surface quality of the wafer and thus affects the bonding quality of the wafer. Summary of the invention

[0005] In order to solve the problem that the existing plasma activation devices still have certain limitations in terms of uniformity and activation efficiency, the present invention provides a new plasma activation device and method for high vacuum wafer bonding.

[0006] The present invention is achieved by adopting the following technical solutions: A plasma activation device for high vacuum wafer bonding, comprising a plasma activation process chamber, an air intake unit, an air extraction unit, and a power source unit; The plasma activation process chamber includes a square chamber shell and an electrode assembly. The square chamber shell is sealed and welded by a top plate, a bottom plate, a front side plate, a rear side plate, a left side plate and a right side plate. An upper air inlet is arranged on the top plate of the square chamber shell. Two scattering plates distributed up and down are fixed at a position below the upper air inlet in the square chamber shell. A spacing is provided between the two scattering plates. Multiple upper air inlet holes are distributed on the two scattering plates and the upper air inlet holes on the two scattering plates are staggered. A wafer transport port is provided at the center of the right side plate of the square chamber shell. A first high vacuum plug valve is provided at the wafer transport port. A side air inlet is provided at the edge of the right side plate of the square chamber shell. An annular air inlet cavity communicating with the side air inlet is fixed on the surrounding edges of the inner side surface of the right side plate of the square chamber shell. Multiple side air inlet holes are distributed on the annular air inlet cavity. A side exhaust port is provided on the center of the left side plate of the square chamber shell. A vacuum barrel with its opening facing left is provided at the center of the inner side surface of the left side plate of the square chamber shell. The opening area of ​​the vacuum barrel is greater than The area of ​​the side exhaust port, the bottom of the exhaust barrel is evenly distributed with a plurality of side exhaust holes, the bottom plate of the square cavity shell is provided with a bottom exhaust port, the electrode assembly includes a positive packaging electrode, a negative packaging electrode and four carrier plates each provided with a plurality of distribution holes, the four carrier plates are horizontally arranged in the square cavity shell and are respectively the first carrier plate, the second carrier plate, the third carrier plate and the fourth carrier plate from top to bottom, the positive packaging electrode and the negative packaging electrode are vertically sealed and fixed to the left side plate of the square cavity shell (in specific implementation, the connection between the positive packaging electrode and the negative packaging electrode and the left side plate of the square cavity shell is sealed by a hard copper sealing ring), one end of the positive packaging electrode and the negative packaging electrode is located outside the square cavity shell and is respectively connected to the positive electrode and the negative electrode of the power source unit, the other end of the positive packaging electrode and the negative packaging electrode is located in the square cavity shell and is correspondingly connected to the four carrier plates, the third carrier plate is aligned with the inner bottom surface of the valve port of the first high vacuum plug valve and is provided with a wafer lifting column for placing wafers; The vacuum unit includes a dry pump and a molecular pump. The square cavity shell is equipped with a first vacuum gauge for detecting the vacuum degree in the square cavity shell. The side vacuum port is connected to the vacuum port of the dry pump through a butterfly valve and a rough vacuum angle valve in sequence. The bottom vacuum port is connected to the vacuum port of the molecular pump through a second high vacuum plug valve. A second vacuum gauge is provided at the vacuum port of the molecular pump. The vacuum port of the molecular pump is connected to the vacuum port of the dry pump through a front-stage angle valve. The air intake unit includes three process gas pipelines and one nitrogen pipeline. The three process gas pipelines and the nitrogen pipeline are arranged side by side. The outlet ends of the three process gas pipelines and the outlet end of the nitrogen pipeline are interconnected to form a total air intake pipeline. The total air intake pipeline is connected to both the upper air inlet and the side air inlet.

[0007] Furthermore, the power source unit is provided with two groups of power sources, a 13.56MHzAE RF power supply and a matching network constitute one group of power sources, a 40kHz intermediate frequency power supply and a transformer constitute another group of power sources, two positive packaging electrodes are provided and one end of each is respectively connected to the positive poles of the two groups of power sources, two negative packaging electrodes are provided and one end of each is respectively connected to the negative poles of the two groups of power sources, the two positive packaging electrodes and the two negative packaging electrodes are respectively located on the front and rear sides of the side exhaust port, and the design of the two groups of power sources facilitates the selection of power sources according to actual working conditions and increases process flexibility.

[0008] Furthermore, the two positive packaged electrodes are distributed up and down, and the other ends of the two positive packaged electrodes are connected by a positive electrode connecting plate; the two negative packaged electrodes are distributed up and down, and the other ends of the two negative packaged electrodes are connected by a negative electrode connecting plate. When a 13.56MHzAE RF power supply and a matching network are selected as the power source, the first carrier plate, the second carrier plate, and the fourth carrier plate are connected to the positive electrode connecting plate, and the third carrier plate is connected to the negative electrode connecting plate, forming a positive-positive-negative-positive electrode arrangement; when a 40kHz intermediate frequency power supply and a transformer are selected as the power source, the first carrier plate, the third carrier plate are connected to the negative electrode connecting plate, and the second carrier plate and the fourth carrier plate are connected to the positive electrode connecting plate, forming a negative-positive-negative-positive electrode distribution. After comparing experiments and simulations, when 13.56MHzAE RF power supply and matching network are selected as the power source, the most appropriate electrode arrangement is positive-positive-negative-positive, and the activated plasma is the most uniform, and the wafer surface quality is the best; when 40kHz intermediate frequency power supply and transformer are selected as the power source, the most appropriate electrode distribution is negative-positive-negative-positive, and the activated plasma is the most uniform, and the wafer surface quality is the best. When using the two sets of power sources, the power source can be selected according to the actual working conditions, increasing process flexibility.

[0009] Furthermore, the electrode assembly also includes four L-shaped mounting blocks, eight front ceramic cylindrical supports, and eight rear ceramic cylindrical supports. The first carrier plate, the second carrier plate, the third carrier plate, and the fourth carrier plate are all square plates. The axes of the eight front ceramic cylindrical supports and the eight rear ceramic cylindrical supports are arranged along the front-to-back direction. One end of the eight front ceramic cylindrical supports is fixed to the inner side of the front side plate of the square cavity shell, and the other end of the eight front ceramic cylindrical supports is supported in pairs below the front end of the four carrier plates. One end of the eight rear ceramic cylindrical supports is fixed to the inner side of the rear side plate of the square cavity shell. The other ends of the eight rear ceramic cylindrical supports are supported in pairs below the rear ends of the four carriers. The left front or left rear ends of the first carrier, the second carrier, the third carrier, and the fourth carrier are all fixed with connecting ears. The positive electrode connecting plate and the negative electrode connecting plate are provided with four mounting grooves that are adapted to the vertical part of the L-shaped mounting block from top to bottom. The connecting ears are bolted to the horizontal part of the corresponding L-shaped mounting block, and the vertical part of the L-shaped mounting block is bolted to the corresponding mounting groove on the positive electrode connecting plate or the negative electrode connecting plate. The connection structure of the four carriers is specific and simplified, and the design of the L-shaped mounting block facilitates different electrode arrangements for the four carriers according to actual working conditions.

[0010] Furthermore, a first shielding box is provided outside the two positive packaged electrodes, and a second shielding box is provided outside the two negative packaged electrodes. Both the first shielding box and the second shielding box are provided with heat dissipation holes, and both the first shielding box and the second shielding box are provided with axial flow fans to ensure normal use of the two positive packaged electrodes and the two negative packaged electrodes.

[0011] Furthermore, a spare exhaust port is provided on the bottom plate of the square cavity shell, a hollow conversion cavity is fixed on the inner side of the bottom plate, a central exhaust port corresponding to the center position of the bottom plate of the square cavity shell is provided on the top surface of one end of the hollow conversion cavity, and a conversion port communicating with the spare exhaust port is provided on the bottom surface of the other end of the hollow conversion cavity. The spare exhaust port can be used to exhaust the square cavity shell together with the side exhaust port and the bottom exhaust port according to the actual working conditions to increase the activation efficiency and process flexibility. At the same time, due to the installation of the molecular pump, the spare exhaust port cannot be set at the center of the bottom plate, and the design of the hollow conversion cavity ensures that the gas can be extracted from the center, making the gas flow more uniform, thereby improving the uniformity of the plasma.

[0012] Furthermore, each process gas pipeline is equipped with a first electronic pressure confirmation switch, a first pneumatic bellows valve, a mass flow meter, and a second pneumatic bellows valve in sequence, and a second electronic pressure confirmation switch and a third pneumatic bellows valve are provided on the nitrogen pipeline. The mass flow meter and the pneumatic bellows valve are designed to facilitate the control of the intake flow and ensure the sealing of the gas circuit.

[0013] Furthermore, reflective plates are fixed to the inner sides of the top plate, bottom plate, front side plate, rear side plate, left plate and right side plate of the square chamber shell to optimize the electric field distribution, making the plasma in the square chamber shell more uniform, and also making the gas distribution more uniform, especially in the corners of the square chamber shell or hard-to-reach places, thereby further improving the uniformity of the reaction.

[0014] Furthermore, heating cover plates are fixed to the outer sides of the top plate, front side plate, rear side plate and right side plate of the square cavity shell, and the gas in the top plate, front side plate, rear side plate and right side plate is released by heating the square cavity shell, so that the square cavity shell achieves an optimal degassing rate.

[0015] A plasma activation method for high vacuum wafer bonding is implemented by using the plasma activation device for high vacuum wafer bonding as described above, and specifically comprises the following steps: 1) opening a first high vacuum plug valve, and sending a wafer from a wafer transport port to a wafer lift column in a square cavity shell, and closing the first high vacuum plug valve after the wafer is placed; 2) starting a dry pump, and a second vacuum gauge monitors the vacuum degree in a molecular pump in real time. When the vacuum degree in the molecular pump does not reach the starting pressure, opening the front angle valve, and evacuating the molecular pump through the dry pump until the vacuum in the molecular pump reaches the starting pressure. When the vacuum degree in the molecular pump reaches the starting pressure, close the front angle valve. When the vacuum degree in the molecular pump reaches the starting pressure, open the rough extraction angle valve to start the rough extraction process. When the first vacuum gauge detects that the vacuum degree in the square cavity shell is less than or equal to 5Pa, open the front angle valve to continue to extract the vacuum in the molecular pump to ensure that the vacuum degree in the molecular pump is less than 5Pa. At this time, start the molecular pump, close the rough extraction angle valve, open the second high vacuum plug valve, and use the molecular pump to evacuate the square cavity shell until the vacuum degree in the square cavity shell reaches the set limit vacuum degree, that is, the vacuum degree reaches 9×10 -6 Pa, the vacuum start is completed, and then the second high vacuum plug valve, molecular pump, and front angle valve are closed in sequence; 3) nitrogen is introduced into the square cavity shell through the nitrogen pipeline, and the vacuum degree in the square cavity shell is monitored in real time through the first vacuum gauge until the vacuum degree in the square cavity shell reaches 5kPa; 4) the rough extraction angle valve is opened, and the vacuum degree in the square cavity shell is pumped to 5Pa through the dry pump; 5) process gas is introduced into the square cavity shell through three process gas pipelines according to actual working conditions; 6) when the pressure in the square cavity shell reaches the dynamic balance of inlet and outlet, the pressure in the square cavity shell is adjusted to 1-200Pa through the butterfly valve; 7) when the gas flow field in the square cavity shell is stable, the power source is started to activate the plasma; 8) after the plasma activation is completed, nitrogen is introduced into the square cavity shell again through the nitrogen pipeline until the pressure in the square cavity shell is restored to the same as the external environment pressure; 9) the dry pump, rough extraction angle valve, and butterfly valve are closed in sequence, and finally the first high vacuum plug valve is opened to take out the wafer after plasma activation.

[0016] The beneficial effects produced by the present invention are as follows: the device described in the present invention improves the uniformity of plasma by designing the gas flow field uniformity of the air intake and exhaust, thereby improving the surface quality of the wafer and further improving the bonding quality of the wafer; at the same time, by setting two groups of power sources and setting a spare exhaust port, the process flexibility is improved, which is convenient for adapting to various process requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0019] Figure 1 It is a schematic diagram of the overall structure of the plasma activation device of the present invention; Figure 2 Schematic diagram of the overall structure of the plasma activation process chamber Figure 1 ; Figure 3 Schematic diagram of the overall structure of the plasma activation process chamber Figure 2 ; Figure 4 It is a structural schematic diagram of the square cavity shell after removing the front side plate; Figure 5 Schematic diagram of the assembly structure of the square cavity shell, exhaust barrel, scattering plate, and annular air intake cavity after removing the front side plate Figure 1 ; Figure 6 Schematic diagram of the assembly structure of the square cavity shell, exhaust barrel, scattering plate, and annular air intake cavity after removing the front side plate Figure 2 ; Figure 7 is a schematic diagram of the structure of the air intake unit; Figure 8 Schematic diagram of the gas path.

[0020] In the figure: 1-square chamber shell, 2-upper air inlet, 3-breaking plate, 4-wafer transport port, 5-first high vacuum plug valve, 6-side air inlet, 7-annular air inlet chamber, 8-side exhaust port, 9-exhaust barrel, 10-bottom exhaust port, 11-positive packaging electrode, 12-negative packaging electrode, 13-first carrier plate, 14-second carrier plate, 15-third carrier plate, 16-fourth carrier plate, 17-wafer lifting column, 18-first vacuum gauge, 19-dry pump, 20-molecular pump, 21-butterfly valve, 22-rough extraction angle valve, 23-second high vacuum plug valve, 24-front angle valve, 25-second Vacuum gauge, 26-nitrogen pipeline, 27-process gas pipeline, 28-positive electrode connecting plate, 29-negative electrode connecting plate, 30-L-type mounting block, 31-front ceramic cylindrical support, 32-first shielding box, 33-second shielding box, 34-spare exhaust port, 35-hollow conversion cavity, 36-center exhaust port, 37-first electronic pressure confirmation switch, 38-first pneumatic bellows valve, 39-mass flowmeter, 40-second pneumatic bellows valve, 41-second electronic pressure confirmation switch, 42-third pneumatic bellows valve, 43-box shell, 44-thermocouple, 45-heating cover. DETAILED DESCRIPTION

[0021] In order to more clearly understand the above-mentioned objectives, features and advantages of the present invention, the scheme of the present invention will be further described below. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0022] In the description, it should be noted that the terms "first" and "second" are only used for descriptive purposes and should not be understood as indicating or implying relative importance. It should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two elements. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0023] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all of the embodiments.

[0024] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0025] like Figures 1 to 8As shown, a plasma activation device for high vacuum wafer bonding includes a plasma activation process chamber, an air intake unit, an air extraction unit, and a power source unit; The plasma activation process chamber includes a square chamber shell 1 and an electrode assembly. The square chamber shell 1 is sealed and welded by a top plate, a bottom plate, a front side plate, a rear side plate, a left side plate and a right side plate. An upper air inlet 2 is arranged on the top plate of the square chamber shell 1. Two scattering plates 3 distributed up and down are fixed at a position below the upper air inlet 2 in the square chamber shell 1. A spacing is provided between the two scattering plates 3. Multiple upper air inlet holes are distributed on the two scattering plates 3, and the upper air inlet holes on the two scattering plates 3 are staggered. A wafer transport port 4 is provided at the center of the right side plate of the square chamber shell 1. The wafer transport port 4 is provided with a first A high vacuum gate valve 5, a side air inlet 6 is provided at the edge of the right side plate of the square chamber shell 1, an annular air inlet cavity 7 communicating with the side air inlet 6 is fixed to the edges of the inner side surface of the right side plate of the square chamber shell 1, and a plurality of side air inlet holes are distributed on the annular air inlet cavity 7, a side air extraction port 8 is provided at the center of the left side plate of the square chamber shell 1, and an air extraction barrel 9 with its opening facing the left side is provided at the center of the inner side surface of the left side plate of the square chamber shell 1 (it is well known to those skilled in the art that the positions of the side air extraction port 8 and the air extraction barrel 9 are both located at the center of the left side plate of the square chamber shell 1, so the air extraction barrel 9 is covered on the left side plate of the square chamber shell 1). On the right side of the side exhaust port 8), the opening area of ​​the exhaust barrel 9 is larger than the area of ​​the side exhaust port 8, and a plurality of side exhaust holes are evenly distributed on the bottom of the exhaust barrel 9. A bottom exhaust port 10 is provided on the bottom plate of the square cavity shell 1. The electrode assembly includes a positive package electrode 11, a negative package electrode 12, and four carrier plates each having a plurality of distribution holes thereon. The four carrier plates are horizontally arranged in the square cavity shell 1 and are respectively the first carrier plate 13, the second carrier plate 14, the third carrier plate 15, and the fourth carrier plate 16 from top to bottom. The positive package electrode 11 and the negative package electrode 12 are vertically sealed and fixed On the left side plate of the square cavity shell 1 (in specific implementation, the connection between the positive package electrode 11 and the negative package electrode 12 and the left side plate of the square cavity shell 1 is sealed by a hard copper sealing ring), one end of the positive package electrode 11 and the negative package electrode 12 is located outside the square cavity shell 1 and is respectively connected to the positive electrode and the negative electrode of the power source unit, and the other end of the positive package electrode 11 and the negative package electrode 12 is located inside the square cavity shell 1 and is correspondingly connected to the four carrier plates, and the third carrier plate 15 is aligned with the inner bottom surface of the valve port of the first high vacuum plug valve 5 and is provided with a wafer lifting column 17 for placing a wafer; The air extraction unit includes a dry pump 19 and a molecular pump 20. The square cavity shell 1 is provided with a first vacuum gauge 18 for detecting the vacuum degree in the square cavity shell (in specific implementation, the first vacuum gauge 18 is provided on a pipeline connected between the side air extraction port 8 of the square cavity shell 1 and the butterfly valve 21). The side air extraction port 8 is also connected to the air extraction port of the dry pump 19 through the butterfly valve 21 and the rough extraction angle valve 22 in sequence. The bottom air extraction port 10 is connected to the air extraction port of the molecular pump 20 through the second high vacuum gate valve 23. The vacuum port of the molecular pump 20 is provided with a second vacuum gauge 25. The vacuum port of the molecular pump 20 is connected to the air extraction port of the dry pump 19 through the front-stage angle valve 24. The air intake unit includes three process gas pipelines 27 and one nitrogen pipeline 26. The three process gas pipelines 27 and the nitrogen pipeline 26 are arranged side by side. The outlet ends of the three process gas pipelines 27 and the outlet ends of the nitrogen pipeline 26 are interconnected to form a total air intake pipeline. The total air intake pipeline is connected to both the upper air inlet 2 and the side air inlet 6.

[0026] Principle description: 1) Two air inlets, namely the upper air inlet 2 and the side air inlet 6, are provided. When in use, the upper air inlet 2 and the side air inlet 6 are simultaneously used for air intake, so that the gas can enter the square cavity shell 1 more evenly, thereby improving the uniformity of the plasma. At the same time, two scattering plates 3 are provided and the upper air inlet holes on the two scattering plates 3 are staggered, so that the gas entering from the upper air inlet 2 can enter the square cavity shell 1 more evenly, and the gas entering from the side air inlet 6 can enter the square cavity shell 1 more evenly by providing an annular air inlet cavity 7, thereby further improving the uniformity of the plasma; 2) Two exhaust ports, namely the side exhaust port 8 and the bottom exhaust port 10, are provided, and the molecular pump 20 and the dry pump 19 are used for exhaust, so as to realize the ultimate vacuum degree in the square cavity shell 1. At the same time, the design of the exhaust barrel 9 also utilizes the uniform flow of gas, thereby further improving the uniformity of the plasma; 3) Multiple distribution holes are provided on each carrier plate, thereby further improving the uniformity of the plasma.

[0027] In specific implementation, the power source unit is provided with two groups of power sources, a 13.56MHzAE RF power supply and a matching network constitute one group of power sources, a 40kHz intermediate frequency power supply and a transformer constitute another group of power sources, two positive packaging electrodes 11 are provided and one end thereof is respectively connected to the positive poles of the two groups of power sources, two negative packaging electrodes 12 are provided and one end thereof is respectively connected to the negative poles of the two groups of power sources, the two positive packaging electrodes 11 and the two negative packaging electrodes 12 are respectively located on the front and rear sides of the side exhaust port 8, and the design of the two groups of power sources facilitates the selection of the power source according to the actual working conditions, thereby increasing the process flexibility.

[0028] In a specific implementation, the two positive packaged electrodes 11 are distributed up and down, and the other ends of the two positive packaged electrodes 11 are connected by a positive electrode connecting plate 28; the two negative packaged electrodes 12 are distributed up and down, and the other ends of the two negative packaged electrodes 12 are connected by a negative electrode connecting plate 29; when a 13.56MHzAE RF power supply and a matching network are selected as the power source, the first carrier plate 13, the second carrier plate 14, and the fourth carrier plate 16 are connected to the positive electrode connecting plate 28, and the third carrier plate 15 is connected to the negative electrode connecting plate 29, forming a positive-positive-negative-positive electrode arrangement; when a 40kHz intermediate frequency power supply and a transformer are selected as the power source, the first carrier plate 13, the third carrier plate 15 are connected to the negative electrode connecting plate 29, and the second carrier plate 14 and the fourth carrier plate 16 are connected to the positive electrode connecting plate 28, forming a negative-positive-negative-positive electrode distribution. After comparing experiments and simulations, when 13.56MHzAE RF power supply and matching network are selected as the power source, the most appropriate electrode arrangement is positive-positive-negative-positive, and the activated plasma is the most uniform, and the wafer surface quality is the best; when 40kHz intermediate frequency power supply and transformer are selected as the power source, the most appropriate electrode distribution is negative-positive-negative-positive, and the activated plasma is the most uniform, and the wafer surface quality is the best. When using the two sets of power sources, the power source can be selected according to the actual working conditions, increasing process flexibility.

[0029] In a specific implementation, the electrode assembly also includes four L-shaped mounting blocks 30, eight front ceramic cylindrical supports 31, and eight rear ceramic cylindrical supports. The first carrier plate 13, the second carrier plate 14, the third carrier plate 15, and the fourth carrier plate 16 are all square plates. The axes of the eight front ceramic cylindrical supports 31 and the eight rear ceramic cylindrical supports are arranged along the front-to-back direction. One end of the eight front ceramic cylindrical supports 31 is fixed to the inner side of the front side plate of the square cavity shell 1, and the other end of the eight front ceramic cylindrical supports 31 is supported in pairs below the front end of the four carrier plates. One end of the eight rear ceramic cylindrical supports is fixed to the inner side of the rear side plate of the square cavity shell 1. The other ends of the eight rear ceramic cylindrical supports are supported in pairs below the rear ends of the four carriers. The left front or left rear ends of the first carrier 13, the second carrier 14, the third carrier 15, and the fourth carrier 16 are all integrally fixed with connecting ears. The positive electrode connecting plate 28 and the negative electrode connecting plate 29 are provided with four mounting grooves adapted to the vertical part of the L-shaped mounting block 30 from top to bottom. The connecting ears are bolted to the horizontal part of the corresponding L-shaped mounting block 30, and the vertical part of the L-shaped mounting block 30 is bolted to the corresponding mounting groove on the positive electrode connecting plate 28 or the negative electrode connecting plate 29. The connection structure of the four carriers is specific and simplified, and the design of the L-shaped mounting block 30 facilitates different electrode arrangements for the four carriers according to actual working conditions.

[0030] During specific implementation, a first shielding box 32 is provided outside the two positive packaged electrodes 11, and a second shielding box 33 is provided outside the two negative packaged electrodes 12. Both the first shielding box 32 and the second shielding box 33 are provided with heat dissipation holes, and both the first shielding box 32 and the second shielding box 33 are provided with axial flow fans to ensure the normal use of the two positive packaged electrodes 11 and the two negative packaged electrodes 12.

[0031] In specific implementation, a spare air extraction port 34 is also provided on the bottom plate of the square chamber shell 1, and a hollow conversion chamber 35 is also fixed on the inner side of the bottom plate. A central air extraction port 36 corresponding to the center position of the bottom plate of the square chamber shell 1 is provided on the top surface of one end of the hollow conversion chamber 35, and a conversion port communicating with the spare air extraction port 34 is provided on the bottom surface of the other end of the hollow conversion chamber 35. The spare air extraction port 34 can subsequently be used together with the side air extraction port 8 and the bottom air extraction port 10 to extract air from the square chamber shell 1 according to actual working conditions to increase activation efficiency and process flexibility. At the same time, due to the installation of the molecular pump 20, the spare air extraction port 34 cannot be set at the center position of the bottom plate, and the design of the hollow conversion chamber 35 ensures that the gas can be extracted from the center, making the gas flow more uniform, thereby improving the uniformity of the plasma.

[0032] In specific implementation, each process gas pipeline 27 is sequentially provided with a first electronic pressure confirmation switch 37, a first pneumatic bellows valve 38, a mass flow meter 39, and a second pneumatic bellows valve 40, and the nitrogen pipeline 26 is provided with a second electronic pressure confirmation switch 41 and a third pneumatic bellows valve 42. The mass flow meter 39 and the pneumatic bellows valve are designed to facilitate the control of the intake flow rate and ensure the sealing of the gas circuit.

[0033] In this specific embodiment, the inner sides of the top plate, bottom plate, front side plate, rear side plate, left side plate and right side plate of the square chamber shell 1 are fixed with reflective plates (in specific implementation, the reflective plates are reflective plates with stainless steel mirror surfaces) to optimize the electric field distribution, making the plasma in the square chamber shell 1 more uniform, and also making the gas distribution more uniform, especially in the corners of the square chamber shell 1 or hard-to-reach places, thereby further improving the uniformity of the reaction.

[0034] In this specific embodiment, a heating cover plate 45 is fixed to the outer sides of the top plate, front side plate, rear side plate and right side plate of the square cavity shell 1. The square cavity shell 1 is heated to release the gas in the top plate, front side plate, rear side plate and right side plate, so that the square cavity shell 1 reaches an optimal degassing rate.

[0035] In this specific embodiment, a thermocouple 44 is provided in the square chamber shell 1 for real-time detection of the temperature in the square chamber shell 1. The first high vacuum gate valve 5 is a square gate valve, which facilitates the wafer to be delivered to the square chamber shell 1 by a vacuum adsorption manipulator. The molecular pump 20 is a TwisTorr 704 FS turbomolecular pump produced by Agilent.

[0036] In this specific embodiment, the device also includes a box shell 43, and the plasma activation process chamber, air intake unit, exhaust unit, and power source unit are integrated in the box shell 43 and arranged in upper and lower partitions, which reduces the footprint of the device and improves the integration of the device.

[0037] A plasma activation method for high vacuum wafer bonding is implemented by using the plasma activation device for high vacuum wafer bonding as described above, and specifically comprises the following steps: 1) opening the first high vacuum plug valve 5, and sending the wafer from the wafer transport port 4 to the wafer lifting column 17 in the square chamber shell 1, and closing the first high vacuum plug valve 5 after the wafer is placed; 2) starting the dry pump 19, and the second vacuum gauge 25 monitors the vacuum degree in the molecular pump 20 in real time. When the vacuum degree in the molecular pump 20 does not reach the starting pressure, opening the front angle valve 24, and evacuating the molecular pump 20 through the dry pump 19 until the vacuum degree in the molecular pump 20 reaches the starting pressure. When the starting pressure is reached, the front angle valve 24 is closed. When the vacuum degree in the molecular pump 20 reaches the starting pressure, the rough extraction angle valve 22 is opened to start the rough extraction process. When the first vacuum gauge 18 detects that the vacuum degree in the square cavity shell 1 is less than or equal to 5Pa, the front angle valve 24 is opened to continue to extract the vacuum in the molecular pump 20 to ensure that the vacuum degree in the molecular pump 20 is less than 5Pa. At this time, the molecular pump 20 is started, the rough extraction angle valve 22 is closed, and the second high vacuum plug valve 23 is opened to evacuate the square cavity shell 1 through the molecular pump 20 until the vacuum degree in the square cavity shell 1 reaches the set limit vacuum degree, that is, the vacuum degree reaches 9×10 -6 Pa, the vacuum pumping start is completed, and then the second high vacuum plug valve 23, the molecular pump 20, and the front angle valve 24 are closed in sequence; 3) nitrogen is introduced into the square chamber shell 1 through the nitrogen pipeline 26, and the vacuum degree in the square chamber shell 1 is monitored in real time through the first vacuum gauge 18 until the vacuum degree in the square chamber shell 1 reaches 5kPa; 4) the rough extraction angle valve 22 is opened, and the vacuum degree in the square chamber shell 1 is pumped to 5Pa through the dry pump 19; 5) process gas is introduced into the square chamber shell 1 through the three-way process gas pipeline 27 according to the actual working conditions; 6) when the square chamber shell 1 reaches a dynamic balance between inlet and outlet, adjust the pressure in the square chamber shell 1 to 1-200Pa through the butterfly valve 21; 7) When the gas flow field in the square chamber shell 1 is stable, start the power source to perform plasma activation; 8) After the plasma activation is completed, introduce nitrogen into the square chamber shell 1 again through the nitrogen pipeline 26 until the pressure in the square chamber shell 1 is restored to be consistent with the external environment pressure; 9) Close the dry pump 19, the rough extraction angle valve 22, and the butterfly valve 21 in turn, and finally open the first high vacuum gate valve 5 to take out the wafer after plasma activation.

[0038] The above is only a specific implementation of the present invention, which enables those skilled in the art to understand or implement the present invention. Although detailed descriptions are given with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments, and they should all be covered by the protection scope of the claims.

Claims

1. A plasma activation device for high vacuum wafer bonding, characterized in that: It includes a plasma activation process chamber, a gas extraction unit, a gas intake unit, and a power source unit; The plasma activation process chamber comprises a square chamber shell (1) and an electrode assembly. The square chamber shell (1) is formed by sealing and welding a top plate, a bottom plate, a front side plate, a rear side plate, a left side plate and a right side plate. An upper air inlet (2) is provided on the top plate of the square chamber shell (1). Two scattering plates (3) distributed up and down are fixed at a position below the upper air inlet (2) in the square chamber shell (1). A spacing is provided between the two scattering plates (3). A plurality of upper air inlet holes are distributed on the two scattering plates (3), and the upper air inlet holes on the two scattering plates (3) are arranged in a staggered manner. The right side of the square chamber shell (1) is provided with a plurality of upper air inlet holes. A wafer transport port (4) is provided at the center of the plate, a first high vacuum plug valve (5) is provided at the wafer transport port (4), a side air inlet (6) is provided at the edge of the right side plate of the square chamber shell (1), an annular air inlet cavity (7) communicating with the side air inlet (6) is fixed to the periphery of the inner side surface of the right side plate of the square chamber shell (1), a plurality of side air inlet holes are distributed on the annular air inlet cavity (7), a side air extraction port (8) is provided at the center of the left side plate of the square chamber shell (1), and an air extraction barrel with its opening facing the left is provided at the center of the inner side surface of the left side plate of the square chamber shell (1). (9), the opening area of ​​the vacuum barrel (9) is larger than the area of ​​the side vacuum port (8), the bottom of the vacuum barrel (9) is evenly distributed with a plurality of side vacuum holes, the bottom plate of the square cavity shell (1) is provided with a bottom vacuum port (10), the electrode assembly comprises a positive package electrode (11), a negative package electrode (12) and four carrier plates each provided with a plurality of distribution holes, the four carrier plates are horizontally arranged in the square cavity shell (1) and are respectively, from top to bottom, a first carrier plate (13), a second carrier plate (14), a third carrier plate (15) and a fourth carrier plate (16), the positive The packaging electrode (11) and the negative packaging electrode (12) are both vertically sealed and fixed to the left side plate of the square cavity shell (1); one end of the positive packaging electrode (11) and the negative packaging electrode (12) are located outside the square cavity shell (1) and are respectively connected to the positive electrode and the negative electrode of the power source unit; the other end of the positive packaging electrode (11) and the negative packaging electrode (12) are located inside the square cavity shell (1) and are correspondingly connected to four carrier plates; the third carrier plate (15) is aligned with the inner bottom surface of the valve port of the first high vacuum plug valve (5) and is provided with a wafer lifting column (17) for placing a wafer; The air extraction unit comprises a dry pump (19) and a molecular pump (20); the square cavity shell (1) is provided with a first vacuum gauge (18) for detecting the vacuum degree in the square cavity shell (1); the side air extraction port (8) is connected to the air extraction port of the dry pump (19) through a butterfly valve (21) and a rough extraction angle valve (22) in sequence; the bottom air extraction port (10) is connected to the air extraction port of the molecular pump (20) through a second high vacuum plug valve (23); a second vacuum gauge (25) is provided at the vacuum port of the molecular pump (20); and the vacuum port of the molecular pump (20) is connected to the air extraction port of the dry pump (19) through a front-stage angle valve (24); The air intake unit comprises three process gas pipelines (27) and one nitrogen pipeline (26); the three process gas pipelines (27) and the nitrogen pipeline (26) are arranged side by side; the outlet ends of the three process gas pipelines (27) and the outlet end of the nitrogen pipeline (26) are interconnected to form a total air intake pipeline; the total air intake pipeline is connected to both the upper air intake port (2) and the side air intake port (6).

2. The plasma activation device for high vacuum wafer bonding according to claim 1, characterized in that: The power source unit is provided with two groups of power sources, a 13.56 MHz AE radio frequency power source and a matching network form one group of power sources, and a 40 kHz intermediate frequency power source and a transformer form another group of power sources, two positive packaging electrodes (11) are provided and one end of each positive packaging electrode is respectively connected to the positive electrodes of the two groups of power sources, two negative packaging electrodes (12) are provided and one end of each negative packaging electrode is respectively connected to the negative electrodes of the two groups of power sources, and the two positive packaging electrodes (11) and the two negative packaging electrodes (12) are respectively located at the front and rear sides of the side exhaust port (8).

3. The plasma activation device for high vacuum wafer bonding according to claim 2, characterized in that: Two positive package electrodes (11) are distributed up and down, and the other ends of the two positive package electrodes (11) are connected via a positive electrode connecting plate (28); two negative package electrodes (12) are distributed up and down, and the other ends of the two negative package electrodes (12) are connected via a negative electrode connecting plate (29); when a 13.56 MHz AE radio frequency power supply and a matching network are selected as a power source, the first carrier plate (13), the second carrier plate (14), and the fourth carrier plate (16) are connected to the positive electrode connecting plate (28), and the third carrier plate (15) is connected to the negative electrode connecting plate (29), forming a positive-positive-negative-positive electrode arrangement; when a 40 kHz intermediate frequency power supply and a transformer are selected as a power source, the first carrier plate (13), the third carrier plate (15) are connected to the negative electrode connecting plate (29), and the second carrier plate (14) and the fourth carrier plate (16) are connected to the positive electrode connecting plate (28), forming a negative-positive-negative-positive electrode arrangement.

4. The plasma activation device for high vacuum wafer bonding according to claim 3, characterized in that: The electrode assembly further comprises four L-shaped mounting blocks (30), eight front ceramic cylindrical supports (31), and eight rear ceramic cylindrical supports; the first carrier plate (13), the second carrier plate (14), the third carrier plate (15), and the fourth carrier plate (16) are all square plates; the axes of the eight front ceramic cylindrical supports (31) and the eight rear ceramic cylindrical supports are arranged along the front-to-back direction; one end of the eight front ceramic cylindrical supports (31) is fixed to the inner side surface of the front side plate of the square cavity shell (1); the other end of the eight front ceramic cylindrical supports (31) is supported in pairs below the front end of the four carrier plates; one end of the eight rear ceramic cylindrical supports is fixed to the inner side surface of the rear side plate of the square cavity shell (1) The other ends of the eight rear ceramic cylindrical supports are supported in pairs below the rear ends of the four carrier plates; the left front or left rear ends of the first carrier plate (13), the second carrier plate (14), the third carrier plate (15) and the fourth carrier plate (16) are integrally fixed with connecting ears; the positive electrode connecting plate (28) and the negative electrode connecting plate (29) are sequentially provided with four mounting grooves adapted to the vertical portion of the L-shaped mounting block (30) from top to bottom; the connecting ears are bolted to the horizontal portion of the corresponding L-shaped mounting block (30); and the vertical portion of the L-shaped mounting block (30) is bolted to the corresponding mounting groove on the positive electrode connecting plate (28) or the negative electrode connecting plate (29).

5. The plasma activation device for high vacuum wafer bonding according to claim 4, characterized in that: A first shielding box (32) is disposed outside the two positive packaged electrodes (11), a second shielding box (33) is disposed outside the two negative packaged electrodes (12), heat dissipation holes are disposed on the first shielding box (32) and the second shielding box (33), and axial flow fans are disposed inside the first shielding box (32) and the second shielding box (33).

6. The plasma activation device for high vacuum wafer bonding according to claim 5, characterized in that: A spare air extraction port (34) is also provided on the bottom plate of the square cavity shell (1), a hollow conversion cavity (35) is also fixed to the inner side surface of the bottom plate, a central air extraction port (36) corresponding to the central position of the bottom plate of the square cavity shell (1) is provided on the top surface of one end of the hollow conversion cavity (35), and a conversion port communicating with the spare air extraction port (34) is provided on the bottom surface of the other end of the hollow conversion cavity (35).

7. The plasma activation device for high vacuum wafer bonding according to claim 6, characterized in that: Each process gas pipeline (27) is provided with a first electronic pressure confirmation switch (37), a first pneumatic bellows valve (38), a mass flow meter (39), and a second pneumatic bellows valve (40) in sequence, and the nitrogen pipeline (26) is provided with a second electronic pressure confirmation switch (41) and a third pneumatic bellows valve (42).

8. The plasma activation device for high vacuum wafer bonding according to claim 7, characterized in that: Reflecting plates are fixed to the inner sides of the top plate, the bottom plate, the front side plate, the rear side plate, the left side plate and the right side plate of the square cavity shell (1).

9. The plasma activation device for high vacuum wafer bonding according to claim 8, characterized in that: A heating cover plate (45) is fixed to the outer side surfaces of the top plate, the front side plate, the rear side plate and the right side plate of the square cavity shell (1).

10. A plasma activation method for high vacuum wafer bonding, implemented by using a plasma activation device for high vacuum wafer bonding as claimed in any one of claims 1 to 9, characterized in that: The method comprises the following steps: 1) opening a first high vacuum plug valve (5), delivering a wafer from a wafer transport port (4) to a wafer lift column (17) in a square chamber shell (1), and closing the first high vacuum plug valve (5) after the wafer is placed; 2) starting a dry pump (19), and monitoring the vacuum degree in a molecular pump (20) in real time with a second vacuum gauge (25); when the vacuum degree in the molecular pump (20) does not reach a starting pressure, opening a front-stage angle valve (24), and evacuating the molecular pump (20) through the dry pump (19) until the vacuum degree in the molecular pump (20) reaches a starting pressure, and closing the front-stage angle valve (24); when the molecular pump (20) reaches a starting pressure, 0) reaches the starting pressure, the rough extraction angle valve (22) is opened to start the rough extraction process. When the first vacuum gauge (18) detects that the vacuum degree in the square chamber shell (1) is less than or equal to 5Pa, the front angle valve (24) is opened to continue to extract the vacuum in the molecular pump (20) to ensure that the vacuum degree in the molecular pump (20) is less than 5Pa. At this time, the molecular pump (20) is started, the rough extraction angle valve (22) is closed, and the second high vacuum plug valve (23) is opened to evacuate the square chamber shell (1) through the molecular pump (20) until the vacuum degree in the square chamber shell (1) reaches the set limit vacuum degree, that is, the vacuum degree reaches 9×10 -6 Pa, the vacuum pumping start is completed, and then the second high vacuum plug valve (23), the molecular pump (20) and the front angle valve (24) are closed in sequence; 3) nitrogen is introduced into the square chamber shell (1) through the nitrogen pipeline (26), and the vacuum degree in the square chamber shell (1) is monitored in real time through the first vacuum gauge (18) until the vacuum degree in the square chamber shell (1) reaches 5 kPa; 4) the rough vacuum angle valve (22) is opened, and the vacuum degree in the square chamber shell (1) is pumped to 5 Pa through the dry pump (19); 5) process gas is introduced into the square chamber shell (1) through the three-way process gas pipeline (27) according to the actual working conditions; 6) when the square After the pressure in the chamber shell (1) reaches a dynamic balance between inlet and outlet, the pressure in the square chamber shell (1) is adjusted to 1-200 Pa through the butterfly valve (21); 7) when the gas flow field in the square chamber shell (1) is stabilized, the power source is started to perform plasma activation; 8) after the plasma activation is completed, nitrogen is introduced into the square chamber shell (1) again through the nitrogen pipeline (26) until the pressure in the square chamber shell (1) is restored to be consistent with the external environment pressure; 9) the dry pump (19), the rough extraction angle valve (22), and the butterfly valve (21) are closed in sequence, and finally the first high vacuum gate valve (5) is opened to take out the wafer after plasma activation.

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