A semiconductor wafer chucking device for thin film deposition

Abstract

This invention relates to the field of semiconductor wafer fabrication and discloses a semiconductor wafer clamping device for thin film deposition, including a chuck substrate and a controller. An adsorption electrode is embedded inside the chuck substrate. A pin channel extending along the thickness direction is formed within the chuck substrate. The clamping device also includes a wafer desorption and lifting module, which comprises: a high-frequency power supply for applying radio frequency voltage to the adsorption electrode; a gas introduction unit for introducing ionized gas into the pin channel; and a pin assembly. The pin assembly is disposed within the pin channel and includes a pin body and a drive mechanism for driving the pin body to rise and fall. A pre-charging unit, electrically connected to the pin body, is used to apply a voltage with the opposite polarity to the residual charge of the electrostatic chuck to the pin body before the pin body performs a lifting action. This invention, through the cooperation of the pre-charging unit, the high-frequency power supply, and the gas introduction unit, forms a dual electrostatic elimination process of pre-charging injection of reverse charge and plasma neutralization.

Description

Technical Field

[0001] This invention relates to the field of semiconductor wafer fabrication, and more specifically to a semiconductor wafer clamping device for thin film deposition. Background Technology

[0002] In semiconductor wafer thin film deposition processes, stable wafer clamping is a core prerequisite for ensuring deposition quality. Currently, the industry commonly uses electrostatic chucks as the core component for wafer clamping. By applying a specific voltage to adsorption electrodes embedded within the chuck substrate, electrostatic attraction is formed between the chuck's upper surface and the wafer through electrostatic induction, thus firmly fixing the semiconductor wafer to the chuck substrate's bearing surface. This ensures that the wafer does not shift due to airflow disturbances, equipment vibrations, or other factors during thin film deposition, guaranteeing the uniformity, flatness, and adhesion of the deposited film. However, after the thin film deposition process is completed, due to the lag in the electrostatic induction between the electrostatic chuck's adsorption electrodes and the wafer surface, and the insulating film on the wafer surface hindering rapid charge dissipation, a certain amount of electrostatic charge remains on both the adsorption electrode surface of the chuck substrate and both sides of the wafer, forming a stable residual electrostatic field. This charge residue problem has become a key bottleneck restricting the refined production of semiconductor wafers.

[0003] Specifically, the hazards of residual static electricity are mainly manifested in several aspects: Firstly, residual static electricity can form a strong electrostatic attraction force, causing the wafer to be tightly adhered to the chuck substrate. This results in the lifting force of the ejector pin assembly having to overcome a large electrostatic attraction force during the subsequent wafer desorption process. Forced lifting can easily cause scratches on the wafer surface, edge cracking, and even lattice defects inside the wafer, seriously affecting the wafer yield. This risk is particularly prominent for thin and brittle semiconductor wafers. Secondly, residual static electricity can cause the wafer surface to carry a fixed polarity charge, which can easily attract tiny impurity particles from the process environment. These impurity particles will adhere to the wafer surface and the deposited thin film, causing defects such as pinholes and blemishes in the thin film, reducing the quality of the thin film deposition, and thus affecting the electrical performance of the semiconductor device, failing to meet the production requirements of high-end semiconductor devices. Summary of the Invention

[0004] The purpose of this invention is to provide a semiconductor wafer clamping device for thin film deposition, thereby solving the above-mentioned technical problems.

[0005] The objective of this invention can be achieved through the following technical solutions: A semiconductor wafer clamping device for thin film deposition includes: a chuck substrate and a controller. The chuck substrate has an upper surface and a lower surface disposed opposite to each other. The upper surface is used to support the semiconductor wafer. An adsorption electrode is embedded inside the chuck substrate. The chuck substrate has a through-hole pin channel extending along the thickness direction; the clamping device also includes a wafer desorption and lifting module, which includes: A ejector pin assembly, disposed within an ejector pin channel, includes an ejector pin body and a drive mechanism for driving the ejector pin body to rise and fall. The pre-charging unit, electrically connected to the ejector pin body, is used to apply a voltage with the opposite polarity to the residual charge of the electrostatic chuck to the ejector pin body before the ejector pin body performs the lifting action. The gas introduction unit is connected to the ejector pin channel and is used to introduce ionized gas into the ejector pin channel. A high-frequency power supply, electrically connected to the adsorption electrode, is used to apply radio frequency voltage to the adsorption electrode during wafer desorption.

[0006] Furthermore, the tip of the ejector pin body is higher than the upper surface of the chuck substrate in the raised state to lift the wafer; in the lowered state, the tip of the ejector pin body is flush with or lower than the upper surface of the chuck substrate.

[0007] Furthermore, an annular gap is formed between the outer wall of the ejector body and the inner wall of the ejector channel. This annular gap is closed when the ejector body is in the descending state and opens when the ejector body is in the rising state, and is connected to the space above the upper surface of the chuck base. The annular gap forms a flow channel during the lifting of the ejector pin body, which is used to guide the plasma generated by the high-frequency power supply on the adsorption electrode to diffuse evenly from the inside of the ejector pin channel to the gap between the upper surface of the chuck substrate and the back of the wafer, so as to neutralize the residual static electricity between the wafer and the chuck substrate.

[0008] Furthermore, the ejector pin body is made of conductive material, and the tip of the ejector pin body has a contact surface for contacting the back of the wafer; The pre-charging unit includes a charge generator and a switching element, one end of which is connected to the charge generator and the other end of which is connected to the ejector pin body; During the lifting process of the ejector pin body, when the contact surface of the ejector pin body contacts the back side of the wafer, the switching element closes, and the charge generator injects charge into the back side of the wafer through the ejector pin body to counteract the residual static electricity on the wafer surface.

[0009] Furthermore, multiple air vents are provided on the side wall of the ejector body. The opening direction of the air vents is inclined upward and forms an angle of 30 to 60 degrees with the axis of the ejector body. The ejector pin body has a gas channel inside, and one end of the gas channel is connected to the gas inlet unit, and the other end is connected to at least one gas outlet. The vent corresponds to the area of ​​the annular gap, and is used to directly introduce the ionized gas delivered by the gas introduction unit into the annular gap during the lifting process of the ejector pin body. The introduced ionized gas is ionized by the radio frequency electric field excited by the high frequency power supply in the annular gap to form plasma.

[0010] Furthermore, the ejector channel includes an upper section and a lower section, the diameter of the upper section is larger than the diameter of the lower section, and a stepped surface is formed at the connection between the upper and lower sections; The ejector body is provided with a limiting boss that mates with the stepped surface. The outer diameter of the limiting boss is smaller than the diameter of the upper section of the ejector channel and larger than the diameter of the lower section of the ejector channel, so as to limit the ejector body during the lifting and lowering process. The annular gap is defined by the outer wall of the limiting boss and the inner wall of the upper section of the ejector channel. The distance between the lower surface of the limiting boss and the step surface gradually increases as the ejector body rises, and the axial length of the annular gap changes synchronously, thereby achieving the regulation of the flow rate and / or velocity of plasma escaping from the annular gap.

[0011] Furthermore, the ejector assembly includes at least three ejector bodies, which are evenly distributed in an equilateral triangle on the chuck base. Each ejector body is correspondingly set with an ejector channel, and each ejector channel is connected to a gas introduction unit. An annular gap is provided between each ejector channel and its corresponding ejector body.

[0012] Furthermore, the driving mechanism is a pneumatic driving mechanism, including a cylinder, a pneumatic pipeline and a pneumatic control valve; the cylinder body is fixed to the chuck base, the piston rod of the cylinder is fixedly connected to the bottom end of the ejector pin body, one end of the pneumatic pipeline is connected to the cylinder, and the other end is connected to an external air source, and the pneumatic control valve is set on the pneumatic pipeline to control the extension and retraction of the cylinder, thereby driving the ejector pin body to rise and fall.

[0013] The beneficial effects of this invention are: (1) This invention achieves dual electrostatic elimination through the coordinated operation of a pre-charging unit, a high-frequency power supply, and a gas introduction unit, which injects reverse charge during pre-charging and neutralizes it with plasma. The pre-charging unit injects reverse charge precisely when the pin contacts the wafer, thus specifically neutralizing residual static electricity on the wafer surface. The gas introduction unit precisely introduces ionized gas into the annular gap through the gas channel and inclined vent of the pin body. The plasma is excited by the high-frequency power supply and diffuses evenly between the wafer and the chuck, further neutralizing residual static electricity and completely weakening the electrostatic adsorption force. At the same time, the axial length of the annular gap gradually changes as the pin rises, dynamically adjusting the plasma flow rate and speed to meet the electrostatic neutralization requirements of different lifting stages. This effectively avoids scratches, damage, and displacement caused by static electricity during wafer desorption, thereby improving the wafer yield. (2) The ejector assembly in this invention uses at least three ejector bodies evenly distributed in an equilateral triangle shape, with a flat contact surface, to ensure that the force on each part is balanced when the wafer is lifted, and to avoid excessive local force that could cause the wafer to bend or break. The drive mechanism adopts a pneumatic drive method, which is suitable for the sealed environment of vacuum thin film deposition, free from impurities and pollution. The lifting speed is precisely adjusted by a pneumatic control valve, and with the guiding effect of the ejector channel and the limiting effect of the limiting boss, the ejector body can be lifted smoothly and accurately, which can prevent the ejector from tilting or coming out, and also avoid excessive lifting speed that could cause impact damage to the wafer, thus ensuring the stability of the wafer clamping and lifting process and protecting the integrity of the wafer. (3) The ejector channel in this invention is divided into an upper section and a lower section to form a stepped surface. It works in conjunction with the limiting boss of the ejector body to achieve precise limiting of ejector lifting and lowering, and avoid component jamming or detachment. The gas channel and the gas outlet of the ejector body are precisely matched to ensure that the ionized gas is efficiently introduced into the annular gap, improve the plasma generation efficiency, and at the same time, the airflow formed by the ionized gas can prevent impurity particles from entering the ejector channel, avoid ejector lifting and lowering jamming, and extend the service life of the device. Attached Figure Description

[0014] The invention will now be further described with reference to the accompanying drawings.

[0015] Figure 1 This is an overall schematic diagram of the present invention; Figure 2 This is a schematic diagram of the chuck mechanism. Figure 3 for Figure 2 Exploded view; Figure 4 for Figure 2 A diagram from another angle; Figure 5 This is a schematic diagram of the internal structure of the ejector pin channel; Figure 6 for Figure 5 A schematic diagram of the working status.

[0016] Figure Descriptions: 1. Semiconductor wafer; 2. Chuck substrate; 3. Adsorption electrode; 4. Ejector pin channel; 41. Upper section; 42. Lower section; 43. Stepped surface; 45. Limiting boss; 5. Wafer desorption and lifting module; 51. Ejector pin assembly; 511. Ejector pin body; 512. Cylinder; 513. Pneumatic pipeline; 514. Pneumatic control valve; 515. External air source; 52. Pre-charge unit; 521. Charge generator; 522. Switching element; 53. Gas introduction unit; 54. High-frequency power supply; 6. Annular gap; 7. Guide channel; 8. Contact surface; 9. Gas outlet; 10. Gas channel. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Please see Figures 1-6 As shown, this invention is a semiconductor wafer clamping device for thin film deposition, mainly used in the semiconductor wafer thin film deposition process. It achieves stable clamping and safe desorption of the wafer, avoids damage to the wafer due to electrostatic adsorption, and ensures the quality of thin film deposition and wafer yield. Its specific structure is as follows: The device includes a chuck substrate 2, a controller, and a wafer desorption and lifting module 5. The components work together to complete the clamping, desorption, and lifting actions of the wafer. Specifically, the chuck substrate 2 serves as the support for the wafer and has an upper surface and a lower surface that are set opposite to each other. The upper surface is a flat support surface used to stably place the semiconductor wafer 1, ensuring that the wafer will not shift during the thin film deposition process. An adsorption electrode 3 is embedded inside the chuck substrate 2. The adsorption electrode 3 works in conjunction with an external circuit to generate electrostatic adsorption force by applying voltage during the thin film deposition process, firmly adsorbing the wafer onto the upper surface of the chuck substrate 2, ensuring the stability of the wafer during the deposition process. Meanwhile, a pin channel 4 extending along its thickness is provided inside the chuck base 2. This pin channel 4 provides guidance for the installation and lifting of the pin assembly 51, ensuring that the pin body 511 will not deviate during the lifting process and guaranteeing the accuracy of the lifting action.

[0019] The wafer desorption and lifting module 5 is the core of realizing wafer desorption and lifting. It integrates the ejector pin assembly 51, the pre-charging unit 52, the gas introduction unit 53 and the high-frequency power supply 54. All components work together to complete the entire process of wafer desorption and lifting from the adsorption state. The ejector assembly 51 is vertically and flexibly disposed within the ejector channel 4, including the ejector body 511 and a drive mechanism for driving the ejector body 511 to rise and fall. In this embodiment, the drive mechanism is a pneumatic drive mechanism adapted to the sealed environment of vacuum thin film deposition. Its specific structure includes a cylinder 512, a pneumatic pipeline 513, and a pneumatic control valve 514. The cylinder body of the cylinder 512 is fixedly connected to the chuck base 2 to ensure that the drive mechanism is installed stably. The piston rod of the cylinder 512 is fixedly connected to the bottom end of the ejector body 511 to realize the direct transmission of power. One end of the pneumatic pipeline 513 is connected to the cylinder 512, and the other end is connected to an external air source 515 to provide a power source for the extension and retraction of the cylinder 512. The pneumatic control valve 514 is disposed on the pneumatic pipeline 513 to control the on / off state of the pneumatic pipeline 513 and the gas flow rate, thereby precisely controlling the extension and retraction of the cylinder 512, and finally driving the ejector body 511 to rise and fall smoothly along the ejector channel 4. The reason for choosing a pneumatic drive mechanism is its simple structure, rapid response, and good sealing performance in a vacuum environment, which will not generate oil, dust or other impurities that contaminate the thin film deposition environment. At the same time, the lifting speed can be precisely adjusted through the pneumatic control valve 514 to adapt to different speed requirements for wafer desorption and lifting, and avoid wafer impact damage caused by excessive speed.

[0020] The lifting and lowering states of the ejector pin body 511 are matched with the clamping and de-attaching states of the wafer: when the ejector pin body 511 is in the lowering state, its top end is flush with or lower than the upper surface of the chuck base 2. At this time, the wafer can be placed stably on the upper surface of the chuck base 2, and the electrostatic adsorption force generated by the adsorption electrode 3 achieves firm clamping; when the ejector pin body 511 is in the rising state, its top end is higher than the upper surface of the chuck base 2, thereby lifting the wafer from the chuck base 2, completing the de-attachment and lifting of the wafer, which facilitates the subsequent transfer of the wafer or process switching.

[0021] The pre-charge unit 52 is electrically connected to the ejector pin body 511. Its core function is to eliminate residual static electricity between the wafer and the chuck substrate 2, preventing wafer damage caused by electrostatic adsorption during the desorption process. In specific implementation, before the ejector pin body 511 performs the lifting action, the pre-charge unit 52 is activated, applying a voltage with the opposite polarity to the residual charge on the electrostatic chuck to the ejector pin body 511. When the tip of the ejector pin body 511 contacts the back of the wafer, a reverse charge is injected into the back of the wafer through the ejector pin body 511, neutralizing the residual static electricity on the wafer surface and laying the foundation for subsequent wafer desorption.

[0022] The gas introduction unit 53 is connected to the ejector pin channel 4 and is used to continuously introduce ionized gas into the ejector pin channel 4. The ionized gas serves as a raw material for plasma generation. Under the action of the high-frequency power supply 54, it is ionized to form plasma, which further helps to neutralize the residual static electricity between the wafer and the chuck substrate 2. At the same time, the introduced gas can also form a stable airflow in the ejector pin channel 4, preventing impurity particles from entering the channel and affecting the ejector pin lifting action, thus ensuring the stability of the device operation.

[0023] The high-frequency power supply 54 is electrically connected to the adsorption electrode 3 and is used to apply radio frequency voltage to the adsorption electrode 3 during wafer desorption. The radio frequency voltage excites the surrounding ionized gas to form plasma. The plasma diffuses through the gap between the ejector pin channel 4 and the ejector pin body 511 to the space between the upper surface of the chuck substrate 2 and the back of the wafer, further neutralizing the residual static electricity between them and weakening the electrostatic adsorption force. Combined with the lifting action of the ejector pin assembly 51, this achieves smooth wafer desorption and avoids problems such as scratches and breakage caused by uneven force on the wafer during desorption. The high-frequency power supply 54 complements the electrostatic neutralization effect of the pre-charging unit 52, forming a dual neutralization mode of pre-charging and plasma, ensuring that residual static electricity is completely eliminated and avoiding problems such as adsorption and displacement during wafer desorption caused by residual static electricity.

[0024] The controller is connected to the adsorption electrode 3, the drive mechanism, the pre-charge unit 52, the gas introduction unit 53, and the high-frequency power supply 54 respectively to realize the timing coordinated control of each component: During thin film deposition, the controller controls the adsorption electrode 3 to generate electrostatic adsorption force to firmly clamp the wafer; when the wafer needs to be desorbed, the controller first controls the pre-charge unit 52 to start, applying a reverse voltage to the ejector body 511, and at the same time controls the gas introduction unit 53 to introduce ionized gas into the ejector channel 4. Then, the controller controls the high-frequency power supply 54 to apply radio frequency voltage to the adsorption electrode 3 to excite plasma to neutralize residual static electricity. Finally, the controller controls the pneumatic control valve 514 of the pneumatic drive mechanism to actuate, causing the piston rod of the cylinder 512 to extend, driving the ejector body 511 to rise, gradually lifting the wafer, and completing the entire desorption and lifting process.

[0025] On the one hand, through the coordinated operation of the pre-charging unit 52, the high-frequency power supply 54, and the gas introduction unit 53, the residual static electricity between the wafer and the chuck substrate 2 is neutralized, weakening the electrostatic adsorption force and avoiding scratches, damage, and displacement caused by static electricity during wafer desorption, thereby improving the wafer yield. On the other hand, the drive mechanism adopts a pneumatic drive method, which is suitable for the sealed environment of vacuum thin film deposition. It has a simple structure and is stably installed. With the guiding effect of the ejector pin channel 4, the ejector pin body 511 can be raised and lowered smoothly, improving the stability of the wafer clamping and lifting process. At the same time, the raising and lowering state of the ejector pin body 511 is precisely matched with the wafer clamping and desorption requirements. Combined with the protective effect of ionized gas, it reduces the entry of impurity particles into the ejector pin channel 4, extends the service life of the device, and ensures the flatness and deposition quality of the wafer during the thin film deposition process, which has strong practicality.

[0026] An annular gap 6 is formed between the outer wall of the ejector body 511 and the inner wall of the ejector channel 4. The annular gap 6 is closed when the ejector body 511 is in the descending state and opens when the ejector body 511 is in the rising state, and is connected to the space above the upper surface of the chuck base 2. The annular gap 6 forms a flow channel 7 during the lifting of the ejector pin body 511. This channel guides the plasma generated by the high-frequency power supply 54 on the adsorption electrode 3 to diffuse evenly from the inside of the ejector pin channel 4 into the gap between the upper surface of the chuck substrate 2 and the back of the wafer, so as to neutralize the residual static electricity between the wafer and the chuck substrate 2.

[0027] In this embodiment, the annular gap 6 is an annular flow channel formed between the outer wall of the limiting boss 45 and the inner wall of the upper section 41 of the ejector channel 4. Its radial width remains constant, while the axial opening and closing size is controlled by the distance between the lower surface of the limiting boss 45 and the step surface 43. During the upward movement of the ejector body 511, the limiting boss 45 moves upward accordingly, and the distance between the two gradually increases, so that the axial flow length of the annular gap 6 gradually increases synchronously, thereby forming a gradual flow channel 7.

[0028] By controlling the opening and closing size of the annular gap 6, the flow cross-sectional area, outflow velocity, and diffusion uniformity of the plasma can be dynamically adjusted. The specific process is as follows: In the initial stage of desorption, the annular gap 6 is controlled at a small opening to concentrate the electric field intensity within the channel, facilitating the efficient excitation of ionized gas to form plasma and constraining the plasma to flow directionally towards the back of the wafer, quickly neutralizing residual static electricity. As the ejector pin continues to rise, the annular gap 6 is appropriately increased, ensuring that the plasma diffuses stably and uniformly throughout the entire area between the wafer and the chuck, and also cooperating with the pre-charge circuit to achieve stable charge injection on the back of the wafer, avoiding local electric field concentration or uneven charge distribution. When the ejector pin further lifts the wafer, the annular gap 6 maintains a larger opening to reduce airflow resistance, allowing the plasma and gas to be discharged smoothly, preventing secondary adsorption, displacement, or scratches on the wafer due to residual static electricity during the lifting process, thus improving the stability and yield of the wafer desorption process.

[0029] The ejector pin body 511 is made of conductive material, and the top of the ejector pin body 511 has a contact surface 8 for contacting the back of the wafer. The ejector pin body 511 is made of conductive material to cooperate with the pre-charge unit 52 to realize charge conduction, and to ensure that the reverse charge generated by the pre-charge unit 52 can be smoothly transferred to the back of the wafer through the ejector pin body 511. The flat contact surface 8 is set to increase the contact area 8 between the ejector pin body 511 and the back of the wafer, avoid excessive local contact pressure to damage the back of the wafer, and at the same time ensure more uniform charge transfer and improve the static neutralization effect. The lifting and lowering states of the ejector pin body 511 are matched with the clamping and de-attaching states of the wafer: when the ejector pin body 511 is in the lowered state, its top end is flush with or lower than the upper surface of the chuck base 2, allowing the wafer to be stably placed on the upper surface of the chuck base 2, where it is firmly clamped by the electrostatic adsorption force generated by the adsorption electrode 3; when the ejector pin body 511 is in the raised state, its top end is higher than the upper surface of the chuck base 2, thereby lifting the wafer from the chuck base 2, completing the wafer de-attachment and lifting, facilitating subsequent wafer transfer or process switching. The ejector pin body 511 is made of conductive material, and its top end has a contact surface 8 for contacting the back of the wafer. The pre-charging unit 52 includes a charge generator 521 and a switching element 522. One end of the switching element 522 is connected to the charge generator 521, and the other end is connected to the ejector pin body 511. During the lifting process of the ejector pin body 511, when the contact surface 8 of the ejector pin body 511 contacts the back side of the wafer, the switch element 522 closes, and the charge generator 521 injects charge into the back side of the wafer through the ejector pin body 511 to counteract residual static electricity on the wafer surface. The switch element 522 controls the on / off state of the pre-charge unit 52, achieving precise timing control of charge injection. When the ejector pin body 511 is not in contact with the wafer, the switch element 522 is open to prevent wasted charge and to prevent premature charge injection leading to uneven charge distribution on the wafer surface, ensuring the accuracy and effectiveness of electrostatic neutralization and laying the foundation for smooth wafer desorption.

[0030] Multiple air vents 8 are provided on the side wall of the ejector body 511. The opening direction of the air vents 8 is inclined upward and forms an angle of 30 degrees to 60 degrees with the axis of the ejector body 511. The ejector body 511 has a gas channel 9 inside, and one end of the gas channel 9 is connected to the gas inlet unit 53, and the other end is connected to at least one gas outlet 8. The vent 8 corresponds to the area of ​​the annular gap 6. During the lifting of the ejector pin body 511, it directly introduces the ionized gas supplied by the gas introduction unit 53 into the annular gap 6. The introduced ionized gas is ionized within the annular gap 6 by the radio frequency electric field excited by the high-frequency power supply 54, forming plasma. Multiple vents 8 ensure uniform ejection of the ionized gas, preventing excessively high or low local gas concentrations. The vents 8 are angled upwards at a 30-60 degree angle to the axis of the ejector pin body 511, guiding the ionized gas upwards along the annular gap 6 and preventing direct impact on the back of the wafer, which could cause wafer displacement. This also ensures that the gas fully fills the annular gap 6. The vents 8, corresponding to the annular gap 6, allow the ionized gas supplied by the gas introduction unit 53 to be directly introduced into the annular gap 6, enabling the ionized gas to be fully ionized within the annular gap 6 by the radio frequency electric field excited by the high-frequency power supply 54, forming plasma. This avoids gas waste and improves plasma generation efficiency.

[0031] The ejector channel 4 includes an upper section 41 and a lower section 42. The diameter of the upper section 41 is larger than that of the lower section 42, and a stepped surface 43 is formed at the connection between the upper section 41 and the lower section 42. The ejector body 511 is provided with a limiting boss 45 that cooperates with the stepped surface 43. The outer diameter of the limiting boss 45 is smaller than the hole diameter of the upper section 41 of the ejector channel 4 and larger than the hole diameter of the lower section 42 of the ejector channel 4, so as to realize the limiting of the ejector body 511 during the lifting and lowering process. The annular gap 6 is defined by the outer wall of the limiting boss 45 and the inner wall of the upper section 41 of the ejector channel 4. The distance between the lower surface of the limiting boss 45 and the step surface 43 gradually increases as the ejector body 511 rises, and the axial length of the annular gap 6 changes synchronously, thereby realizing the regulation of the flow rate and / or velocity of plasma escaping from the annular gap 6.

[0032] The purpose of setting the annular gap 6 is to provide a flow channel for plasma, allowing it to diffuse from the ejector pin channel 4 to the area between the upper surface of the chuck substrate 2 and the back of the wafer, neutralizing residual static electricity. The axial length of the annular gap 6 can change synchronously with the ejector pin's rise because the plasma flow rate and velocity requirements differ at different lifting stages: In the initial lifting stage, the ejector pin rises to a low height, and the annular gap 6 is small, allowing the plasma concentration to be concentrated and quickly neutralizing residual static electricity on the surface; in the middle lifting stage, the ejector pin continues to rise, and the annular gap 6 increases, ensuring that the plasma diffuses uniformly to the entire wafer area; in the later lifting stage, the annular gap 6 reaches its maximum, reducing airflow resistance, preventing local plasma accumulation that could damage the wafer, and achieving dynamic adaptation of plasma flow rate and velocity, further improving desorption safety.

[0033] The ejector assembly 51 includes at least three ejector bodies 511, which are evenly distributed in an equilateral triangle on the chuck substrate 2. Each ejector body 511 corresponds to an ejector channel 4, and each ejector channel 4 is connected to a gas introduction unit 53. An annular gap 6 is provided between each ejector channel 4 and its corresponding ejector body 511. The arrangement of at least three ejector bodies 511 in an equilateral triangle ensures that the force is evenly distributed when the ejector bodies 511 lift the wafer, preventing bending, scratches, or breakage due to excessive local force and ensuring the integrity of the wafer. Furthermore, the presence of an annular gap 6 between each ejector body 511 and its independent ejector channel 4 allows ionized gas and plasma to diffuse from multiple evenly distributed locations below the wafer, ensuring more uniform neutralization of residual static electricity on the back of the wafer by the plasma and further improving desorption safety.

[0034] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A semiconductor wafer clamping device for thin film deposition, comprising: The chuck substrate and controller have an upper and lower surface that are arranged opposite to each other. The upper surface is used to support a semiconductor wafer. An adsorption electrode is embedded inside the chuck substrate. The chuck substrate is characterized by having a through-hole pin channel extending along the thickness direction; the clamping device further includes a wafer desorption and lifting module, which comprises: A ejector pin assembly, disposed within an ejector pin channel, includes an ejector pin body and a drive mechanism for driving the ejector pin body to rise and fall. The pre-charging unit, electrically connected to the ejector pin body, is used to apply a voltage with the opposite polarity to the residual charge of the electrostatic chuck to the ejector pin body before the ejector pin body performs the lifting action. The gas introduction unit is connected to the ejector pin channel and is used to introduce ionized gas into the ejector pin channel. A high-frequency power supply, electrically connected to the adsorption electrode, is used to apply radio frequency voltage to the adsorption electrode during wafer desorption.

2. The semiconductor wafer clamping device for thin film deposition according to claim 1, characterized in that, When the ejector pin body is in the raised state, its tip is higher than the upper surface of the chuck substrate to lift the wafer; when the ejector pin body is in the lowered state, its tip is flush with or lower than the upper surface of the chuck substrate.

3. The semiconductor wafer clamping device for thin film deposition according to claim 2, characterized in that, An annular gap is formed between the outer wall of the ejector body and the inner wall of the ejector channel. The annular gap is closed when the ejector body is in the descending state and opens when the ejector body is in the rising state, and is connected to the space above the upper surface of the chuck base. The annular gap forms a flow channel during the lifting of the ejector pin body, which is used to guide the plasma generated by the high-frequency power supply on the adsorption electrode to diffuse evenly from the inside of the ejector pin channel to the gap between the upper surface of the chuck substrate and the back of the wafer, so as to neutralize the residual static electricity between the wafer and the chuck substrate.

4. The semiconductor wafer clamping device for thin film deposition according to claim 1 or 3, characterized in that, The ejector pin body is made of conductive material, and the top of the ejector pin body has a contact surface for contacting the back of the wafer. The pre-charging unit includes a charge generator and a switching element, one end of which is connected to the charge generator and the other end of which is connected to the ejector pin body; During the lifting process of the ejector pin body, when the contact surface of the ejector pin body contacts the back side of the wafer, the switching element closes, and the charge generator injects charge into the back side of the wafer through the ejector pin body to counteract the residual static electricity on the wafer surface.

5. The semiconductor wafer clamping device for thin film deposition according to claim 4, characterized in that, Multiple air vents are provided on the side wall of the ejector body. The opening direction of the air vents is inclined upward and forms an angle of 30 to 60 degrees with the axis of the ejector body. The ejector pin body has a gas channel inside, and one end of the gas channel is connected to the gas inlet unit, and the other end is connected to at least one gas outlet. The vent corresponds to the area of ​​the annular gap, and is used to directly introduce the ionized gas delivered by the gas introduction unit into the annular gap during the lifting process of the ejector pin body. The introduced ionized gas is ionized by the radio frequency electric field excited by the high frequency power supply in the annular gap to form plasma.

6. The semiconductor wafer clamping device for thin film deposition according to claim 5, characterized in that, The ejector channel consists of an upper section and a lower section. The diameter of the upper section is larger than that of the lower section, and a stepped surface is formed at the connection between the upper and lower sections. The ejector body is provided with a limiting boss that mates with the stepped surface. The outer diameter of the limiting boss is smaller than the diameter of the upper section of the ejector channel and larger than the diameter of the lower section of the ejector channel, so as to limit the ejector body during the lifting and lowering process. The annular gap is defined by the outer wall of the limiting boss and the inner wall of the upper section of the ejector channel. The distance between the lower surface of the limiting boss and the step surface gradually increases as the ejector body rises, and the axial length of the annular gap changes synchronously, thereby achieving the regulation of the flow rate and / or velocity of plasma escaping from the annular gap.

7. The semiconductor wafer clamping device for thin film deposition according to claim 6, characterized in that, The ejector assembly includes at least three ejector bodies, which are evenly distributed in an equilateral triangle on the chuck base. Each ejector body is correspondingly set with an ejector channel, and each ejector channel is connected to a gas introduction unit. An annular gap is provided between each ejector channel and its corresponding ejector body.

8. The semiconductor wafer clamping device for thin film deposition according to claim 1, characterized in that, The drive mechanism is a pneumatic drive mechanism, including a cylinder, a pneumatic pipeline and a pneumatic control valve; the cylinder body is fixed to the chuck base, the piston rod of the cylinder is fixedly connected to the bottom end of the ejector pin body, one end of the pneumatic pipeline is connected to the cylinder and the other end is connected to an external air source, and the pneumatic control valve is set on the pneumatic pipeline to control the extension and retraction of the cylinder, thereby driving the ejector pin body to rise and fall.

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