Electrostatic discharge method and apparatus for electrostatic chuck

Abstract

The application provides an electrostatic chucking method and device, the device comprises: an electrostatic chucking device provided with wafer pins for lifting a wafer; the electrostatic chucking device is provided with a power supply for providing a fixed reverse voltage to the wafer when a first power supply signal is received and providing a ladder-increasing ladder reverse voltage to the wafer when a second power supply signal is received; and a processing unit for judging whether a pre-desorption position is reached within a predetermined time period after the wafer pins are started to lift the wafer and sending the first power supply signal for providing the fixed reverse voltage or the second power supply signal for providing the ladder-increasing ladder reverse voltage to the power supply according to the judgment result. The application increases the judgment time by setting the reverse voltage and the ladder-increasing ladder reverse voltage applied to the electrostatic chucking device, effectively solves the problem of electrostatic residue of the wafer after etching in a process cavity and reduces the risk of wafer deviation during transmission and wafer damage caused by the wafer pins.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor manufacturing equipment design, and in particular relates to a method and apparatus for electrostatic discharge of an electrostatic chuck. Background Technology

[0002] In the integrated circuit chip manufacturing industry, the entire wafer processing flow generally includes processes such as photolithography, etching, ion implantation, metal deposition, and core packaging. In plasma etching, the etching machine faithfully transfers the photoresist patterns, such as lines, surfaces, or holes, generated by photolithography onto the underlying material to form the complex architecture required for the entire integrated circuit. In the packaging field, plasma etching is also required for overall wafer thinning and back-end packaging. The completion of these processes typically involves placing the wafer on a chuck within the reaction chamber of semiconductor processing equipment for processing. The chuck serves to support and fix the wafer, and control the wafer temperature during the process. An electrostatic chuck is a chuck structure that uses electrostatic force to fix the wafer, eliminating the disadvantages of traditional mechanical chucks, such as complex structures and reduced effective wafer processing area.

[0003] An electrostatic chuck uses electrostatic attraction to hold a wafer on a chuck, reducing chipping, increasing the effective processing area of ​​the wafer, and reducing the deposition of corrosion particles on the wafer surface. An electrostatic chuck typically includes a chuck 101, wafer pins 102, a drive mechanism (not shown), and a DC power supply (not shown). The chuck 101 supports and holds the wafer 103. The DC power supply is electrically connected to embedded electrodes within the electrostatic chuck to provide power to these electrodes. The wafer pins 102, driven by the drive mechanism, reciprocate up and down, thereby lifting the wafer 103 from or placing it on the support surface of the chuck 101. Figure 1 As shown.

[0004] During the process, a robotic arm places wafer 103 on the top of wafer pin 102. Wafer pin 102 descends, placing wafer 103 onto the support surface of chuck 101. A DC power supply applies a DC voltage to the embedded electrodes, inducing electrostatic charges on the surface of wafer 103. These charges create an electrostatic attraction between wafer 103 and the embedded electrodes, which secures the wafer to the support surface of the electrostatic chuck. After the process is complete, a reverse voltage is applied to the embedded electrodes, inducing electrostatic charges of opposite polarity to those generated during the process on the surface of wafer 103, thus releasing static electricity and eliminating the electrostatic attraction.

[0005] However, in practical applications, applying reverse voltage as described above cannot completely eliminate static charges on the electrodes and wafers. Static charge elimination is typically affected by various factors, such as process conditions, the magnitude of the reverse voltage, and the duration of its application. Therefore, using reverse voltage alone to remove static charges from electrodes and wafers is insufficient to overcome these factors, making thorough removal difficult. The presence of residual charge on the electrodes and wafers will cause the following problems: 1. Due to the incomplete release of static electricity, the wafer is prone to misalignment when exiting the process chamber, such as... Figure 2 As shown, this not only affects wafer quality but also causes machine transfer alarms. Frequent electrostatic discharge (ESD) alarms lead to frequent downtime for process chamber replacements, affecting machine uptime. Furthermore, the replacement cost of ceramic chucks is extremely high. 2. If there is a significant amount of ESD residue, the wafer is prone to breakage during the wafer pin as it rises, leading to an increased defect rate. Figure 3 As shown. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method and apparatus for electrostatic discharge of an electrostatic chuck, which solves the problems of machine downtime and wafer breakage caused by the inability to completely discharge static electricity from the electrostatic chuck in the prior art.

[0007] To achieve the above and other related objectives, the present invention provides a method for electrostatic release of an electrostatic chuck, the method comprising: step S1, applying a first reverse voltage to a wafer via the electrostatic chuck to release the static electricity adsorbed on the wafer by the first step, thereby activating the wafer pins of the electrostatic chuck to lift the wafer; step S2, determining whether the wafer pins have reached the pre-de-adsorption position within a first time period; if not, proceeding to step S3, if yes, proceeding to step S6; step S3, applying a second reverse voltage to the wafer via the electrostatic chuck to release the static electricity adsorbed on the electrostatic chuck by the second step. The electrostatic charge on the wafer triggers the wafer pin of the electrostatic chuck to lift the wafer; Step S4: Determine whether the wafer pin reaches the pre-de-adsorption position within the second time period; if not, proceed to Step S5; if yes, proceed to Step S6; Step S5: Apply a stepped-increasing third reverse voltage to the wafer to the maximum output voltage of the power supply through the electrostatic chuck, and determine whether the wafer pin reaches the pre-de-adsorption position during the voltage increase period; if yes, proceed to Step S6; if not, proceed to Step S7; Step S6: The wafer pin lifts the wafer to the target position; Step S7: Machine alarm sounds.

[0008] Optionally, the first reverse voltage ranges from 800 volts to 1200 volts, and the first time period ranges from 15 seconds to 30 seconds.

[0009] Optionally, the range of the second reverse voltage is between 800 volts and 1200 volts, and the range of the second time period is between 15 seconds and 30 seconds.

[0010] Optionally, the voltage increase of the third reverse voltage is between 400 volts and 600 volts for each increment, and the third reverse voltage is not greater than the maximum output voltage of the power supply.

[0011] Optionally, the height of the pre-desorption position is between 1 / 50 and 1 / 2 of the height of the target position.

[0012] Optionally, in step S5, after applying the third reverse voltage of each step to the wafer via the electrostatic chuck, the wafer pin of the electrostatic chuck is activated to lift the wafer and it is determined whether the wafer pin reaches the pre-de-adsorption position within the third time period. If yes, the power supply to the electrostatic chuck is stopped; if no, the voltage applied to the wafer via the electrostatic chuck is increased.

[0013] Furthermore, the third time period is between 15 and 30 seconds.

[0014] The present invention also provides an electrostatic discharge device for an electrostatic chuck, comprising: an electrostatic chuck for adsorbing a wafer, the electrostatic chuck having a wafer pin for lifting the wafer; the electrostatic chuck being equipped with a power supply for providing a fixed reverse voltage to the wafer through the electrostatic chuck when a first power supply signal is received, and providing a stepped reverse voltage to the wafer through the electrostatic chuck when a second power supply signal is received; and a processing unit connected to the electrostatic chuck and the power supply for determining whether the wafer pin has reached a pre-desorption position within a predetermined time period after the wafer pin is activated to lift the wafer, and sending a first power supply signal providing a fixed reverse voltage or a second power supply signal providing a stepped reverse voltage to the power supply based on the determination result.

[0015] Optionally, the wafer lifting position of the wafer pin of the electrostatic chuck includes a pre-desorption position and a target position, wherein the target position is higher than the pre-desorption position, and the height of the pre-desorption position is between 1 / 50 and 1 / 2 of the height of the target position.

[0016] Optionally, the power supply provides a fixed reverse voltage to the wafer via the electrostatic chuck, ranging from 800 volts to 1200 volts.

[0017] Optionally, the predetermined time period is between 15 seconds and 30 seconds.

[0018] Optionally, the step reverse voltage provided by the power supply to the wafer via the electrostatic chuck increases by an increment of 400 volts to 600 volts each time, and the step reverse voltage is not greater than the maximum output voltage of the power supply.

[0019] Optionally, the device also includes an alarm, which is used to issue an alarm if the wafer pin has not reached the pre-de-adsorption position when the power supply provides a stepped reverse voltage to the wafer through the electrostatic chuck to the maximum output voltage of the power supply.

[0020] As described above, the electrostatic discharge method and apparatus for the electrostatic chuck of the present invention have the following beneficial effects:

[0021] 1) By setting the reverse voltage applied to the electrostatic chuck and the stepped reverse voltage, the present invention can effectively solve the problem of electrostatic residue on the wafer after etching in the process cavity, and can effectively reduce the risk of wafer shifting during transport and being broken by wafer pins due to electrostatic adsorption.

[0022] 2) By increasing the judgment time for the wafer pin to be raised to the pre-de-adsorption position, this invention can effectively reduce machine alarms caused by electrostatic adsorption, improve machine availability, and reduce the cost of parts replacement.

[0023] 3) The method and apparatus of the present invention are simple and can effectively reduce wafer transfer abnormalities and breakage caused by poor electrostatic discharge, and extend the service life of ceramic chucks. It has broad application prospects in the field of semiconductor integrated circuit manufacturing. Attached Figure Description

[0024] Figure 1 The diagram shows a structural schematic of an electrostatic chuck in the prior art.

[0025] Figure 2 This diagram illustrates how an electrostatic chuck in the prior art can cause a wafer to shift when it exits the process cavity due to the inability of the wafer to fully release static electricity.

[0026] Figure 3 This diagram illustrates how a wafer breaks when the wafer pins rise, caused by excessive static electricity residue in an existing electrostatic chuck.

[0027] Figure 4 The diagram shows a flow chart of the electrostatic discharge method for the electrostatic chuck of the present invention.

[0028] Figures 5-7 The diagram shows the structure of the electrostatic discharge method of the electrostatic chuck of the present invention during the electrostatic discharge process.

[0029] Figure 8The diagram shown is a structural schematic of the electrostatic discharge device of the electrostatic chuck of the present invention.

[0030] Component designation explanation

[0031] 101 Chuck

[0032] 102 Wafer Pins

[0033] 103 Wafer

[0034] 200 electrostatic chuck

[0035] 201 Chuck

[0036] 202 Wafer Pins

[0037] 203 wafer

[0038] 204 Power Supply

[0039] 205 processing units

[0040] Steps S1 to S7 Detailed Implementation

[0041] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0042] Please see Figures 4-8 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0043] Example 1

[0044] This embodiment provides a method for electrostatic discharge of an electrostatic chuck. The electrostatic chuck 200 includes a chuck 201 and a wafer pin 202. The electrostatic chuck 200 is provided with a driving device. The wafer pin 202 can move up and down reciprocally under the drive of the driving device, thereby lifting the wafer 203 from the bearing surface of the chuck 201 or placing the wafer 203 on the bearing surface of the chuck 201. In this embodiment, the lifting positions of the wafer pin 202 include a pre-de-adsorption position H1 and a target position H2. The target position H2 is higher than the pre-de-adsorption position H1. The height of the pre-de-adsorption position H1 is between 1 / 50 and 1 / 2 of the height of the target position H2. The pre-de-adsorption position H1 is a position where the adsorption force between the wafer 203 and the electrostatic chuck 200 is substantially overcome. The target position H2 can be a position for operating the wafer, such as a robotic arm. For example, the distance between the target position H2 and the bearing surface of the electrostatic chuck 200 can be 5 cm, while the distance between the pre-de-adsorption position H1 and the bearing surface of the electrostatic chuck 200 can be between 0.1 mm and 2.5 cm. The electrostatic chuck 200 is connected to a power supply 204. During adsorption, the power supply 204 applies a DC voltage to the electrostatic chuck 200, thereby inducing static charges on the surface of the wafer 203. These static charges cause electrostatic attraction between the wafer 203 and the embedded electrodes, which fixes the wafer 203 to the bearing surface of the electrostatic chuck 200. When releasing static electricity, the power supply 204 applies a reverse voltage with the opposite polarity to the static charges on the wafer 203 through the electrostatic chuck 200 to release static electricity and eliminate electrostatic attraction.

[0045] like Figure 4 As shown, the electrostatic discharge method of the electrostatic chuck 200 includes:

[0046] like Figure 4 As shown, in step S1, after the wafer 203 is processed in the process chamber, the power supply 204 applies a first reverse voltage to the wafer 203 through the electrostatic chuck 200 to release the static electricity of the wafer 203 adsorbed on the electrostatic chuck 200 for the first time, and activates the wafer pin 202 of the electrostatic chuck 200 to lift the wafer 203.

[0047] Figure 5The wafer 203 is shown fixed to an electrostatic chuck 200 in a process chamber used for plasma processing. Plasma processing includes, for example, etching, plasma-enhanced chemical vapor deposition (PECVD), etc. It should be understood that the process chamber can be any type of process chamber including the electrostatic chuck 200, and therefore other processes can be performed within the process chamber. For example, the process chamber can be a capacitively coupled plasma (CCP) chamber, an inductively coupled plasma (ICP) chamber, a high-density plasma (HDP) chamber, etc.

[0048] The first reverse voltage can be between 800 volts and 1200 volts. For example, the first reverse voltage can be 900 volts, 1000 volts, 1100 volts, etc.

[0049] like Figure 4 As shown, then step S2 is performed to determine whether the wafer pin 202 has reached the pre-desorption position H1 within the first time period; if not, then step S3 is performed; if yes, then step S6 is performed. The range of the first time period is between 15 seconds and 30 seconds.

[0050] Since the static electricity in wafer 203 may not have been completely discharged in step S1, leaving a significant amount of residual static electricity, there may be considerable resistance when the wafer pin 202 of the electrostatic chuck 200 is activated to lift wafer 203. The lifting time for wafer 203 may also be prolonged. In this embodiment, the first time period is set to between 15 and 30 seconds to avoid the problem of machine alarms due to prolonged lifting time, which would reduce machine availability. Furthermore, if the wafer pin 202 cannot reach the pre-de-adsorption position H1 within the first time period, the machine will not alarm temporarily and will proceed to step S3 to continue discharging static electricity. If the wafer pin 202 can reach the pre-de-adsorption position H1 within the first time period, such as... Figure 6 As shown, in step S6, the wafer pin 202 lifts the wafer 203 to the target position H2, as... Figure 7 As shown.

[0051] like Figure 4As shown, if the wafer pin 202 cannot reach the pre-de-adsorption position H1 within the first time period, step S3 is performed. The power supply 204 applies a second reverse voltage to the wafer 203 through the electrostatic chuck 200 to release the static electricity of the wafer 203 adsorbed on the electrostatic chuck 200 for the second time, and activates the wafer pin 202 of the electrostatic chuck 200 to lift the wafer 203. The range of the second reverse voltage is between 800 volts and 1200 volts. For example, the first reverse voltage can be 900 volts, 1000 volts, 1100 volts, etc. This step can further release the static electricity of the wafer 203 to reduce the problem of static electricity residue on the wafer 203.

[0052] like Figure 4 As shown, step S4 is then performed to determine whether the wafer pin 202 has reached the pre-desorption position H1 within the second time period; if not, step S5 is performed; if yes, step S6 is performed. The range of the second time period is between 15 seconds and 30 seconds.

[0053] Because static electricity in wafer 203 may not be completely discharged in step S3, leaving some residual static electricity, some resistance may occur when the wafer pin 202 of the electrostatic chuck 200 is activated to lift wafer 203, and the lifting time may be relatively long. In this embodiment, the second time period is set to between 15 and 30 seconds to avoid the problem of machine alarms caused by a long lifting time, which would reduce the machine's available time. Furthermore, if the wafer pin 202 cannot reach the pre-de-adsorption position H1 within the second time period, the machine will not alarm temporarily and will enter step S3 to continue discharging static electricity. If the wafer pin 202 can reach the pre-de-adsorption position H1 within the second time period, such as Figure 6 As shown, in step S6, the wafer pin 202 lifts the wafer 203 to the target position H2, as... Figure 7 As shown.

[0054] like Figure 4 As shown, if the wafer pin 202 cannot reach the pre-desorption position H1 within the second time period, then step S5 is performed. The power supply 204 applies a step-increasing third reverse voltage to the wafer 203 through the electrostatic chuck 200 to the maximum output voltage of the power supply 204, and determines whether the wafer pin 202 has reached the pre-desorption position H1 during the voltage increase period. If yes, then step S6 is performed; otherwise, then step S7 is performed.

[0055] In this embodiment, the voltage increase of the third reverse voltage is between 400 volts and 600 volts each time. For example, the voltage increase of the third reverse voltage each time can be 400 volts, 450 volts, 500 volts, 550 volts, 600 volts, etc., and the third reverse voltage is not greater than the maximum output voltage of the power supply 204.

[0056] In step S5, after applying the third reverse voltage of each step to the wafer 203 through the electrostatic chuck 200, the wafer pin 202 of the electrostatic chuck 200 is activated to lift the wafer 203 and it is determined whether the wafer pin 202 reaches the pre-de-adsorption position H1 within the third time period. If yes, the power supply to the electrostatic chuck 200 is stopped; if no, the voltage applied to the wafer 203 through the electrostatic chuck 200 is increased. The range of the third time period is between 15 seconds and 30 seconds.

[0057] For example, firstly, a third reverse voltage of 500 volts is applied to the wafer 203 via the electrostatic chuck 200 to initiate the first activation of the electrostatic chuck 200. The wafer pin 202 is then used to lift the wafer 203, and it is determined whether the wafer pin 202 reaches the pre-de-adsorption position H1 within 15 to 30 seconds. If so, ... Figure 6 As shown, step S6 is performed, in which the wafer 203 is raised to the target position H2, as follows. Figure 7 As shown, if not, a third reverse voltage of 1000 volts is applied to the wafer 203 via the electrostatic chuck 200 to initiate a second activation of the electrostatic chuck 200. The wafer pin 202 lifts the wafer 203 and it is determined whether the wafer pin 202 reaches the pre-de-adsorption position H1 within 15 to 30 seconds. If so, ... Figure 6 As shown, step S6 is performed, in which the wafer 203 is raised to the target position H2, as follows. Figure 7 As shown, if not, a third reverse voltage of 1500 volts is applied to the wafer 203 through the electrostatic chuck 200, and so on, until the round pin reaches the pre-desorption position H1 or the third reverse voltage reaches the maximum output voltage of the power supply 204. If the round pin has not reached the pre-desorption position H1 when the third reverse voltage reaches the maximum output voltage of the power supply 204, then step S7 is performed, the machine issues an alarm, and waits for the staff to handle it.

[0058] Practical application verification shows that, for ceramic chucks 201 with an RF time exceeding 5000 hours, the electrostatic discharge method of this invention reduces the risk of wafer 203 transfer misalignment after etching 100 wafers 203 to zero. For ceramic chucks 201 with an RF time exceeding 8000 hours, the electrostatic discharge method reduces the risk of wafer 203 breakage after etching 300 wafers 203 to zero. This electrostatic discharge method reduces the number of times maintenance is required due to process cavity transfer anomalies; for example, each process cavity anomaly maintenance requires 24 hours and affects daily production capacity by approximately 100-200 wafers. This electrostatic discharge method extends the service life of ceramic chucks 201 from approximately 2 years (RF time 10950) to approximately 3 years (RF time 16425), resulting in significant cost savings.

[0059] This invention effectively solves the problem of electrostatic residue on the wafer 203 after etching in the process cavity by setting a reverse voltage applied to the electrostatic chuck 200 and a stepped increase in the reverse voltage. This effectively reduces the risk of the wafer 203 shifting during transport and being broken by the wafer pin 202 due to electrostatic adsorption. Simultaneously, by increasing the judgment time for the wafer pin 202 to rise to the pre-desorption position H1, this invention effectively reduces machine alarms caused by electrostatic adsorption, improves machine availability, and reduces component replacement costs.

[0060] Example 2

[0061] like Figure 8 As shown, this embodiment provides an electrostatic discharge device for an electrostatic chuck 200, the electrostatic discharge device including an electrostatic chuck 200, a power supply 204 and a processing unit 205.

[0062] The electrostatic chuck 200 is used to pick up the wafer 203. The electrostatic chuck 200 is provided with a wafer pin 202, which is used to lift the wafer 203. The electrostatic chuck 200 includes a chuck 201 and a wafer pin 202. The electrostatic chuck 200 is provided with a driving device (not shown). The wafer pin 202 can move up and down reciprocally under the drive of the driving device, thereby lifting the wafer 203 from the bearing surface of the chuck 201 or placing the wafer 203 on the bearing surface of the chuck 201. In this embodiment, the lifting positions of the wafer pin 202 include a pre-de-adsorption position H1 and a target position H2. The target position H2 is higher than the pre-de-adsorption position H1. The height of the pre-de-adsorption position H1 is between 1 / 50 and 1 / 2 of the height of the target position H2. The pre-de-adsorption position H1 is a position where the adsorption force between the wafer 203 and the electrostatic chuck 200 is substantially overcome. For example, the distance between the target position H2 and the bearing surface of the electrostatic chuck 200 can be 5 cm, while the distance between the pre-de-adsorption position H1 and the bearing surface of the electrostatic chuck 200 can be between 0.1 mm and 2.5 cm. The electrostatic chuck 200 is connected to a power supply 204. During adsorption, the power supply 204 applies a DC voltage to the electrostatic chuck 200, thereby inducing static charges on the surface of the wafer 203. These static charges cause electrostatic attraction between the wafer 203 and the embedded electrodes, which fixes the wafer 203 to the bearing surface of the electrostatic chuck 200. When releasing static electricity, the power supply 204 applies a reverse voltage with the opposite polarity to the static charges on the wafer 203 through the electrostatic chuck 200 to release static electricity and eliminate electrostatic attraction.

[0063] The electrostatic chuck 200 is equipped with a power supply 204, which provides a fixed reverse voltage to the wafer 203 via the electrostatic chuck 200 when a first power supply signal is received, and provides a stepped reverse voltage to the wafer 203 via the electrostatic chuck 200 when a second power supply signal is received. A processing unit 205, connected to the electrostatic chuck 200 and the power supply 204, is used to determine whether the wafer pin 202 has reached the pre-de-adsorption position H1 within a predetermined time period after the wafer pin 202 is activated to lift the wafer 203, and sends a first power supply signal providing a fixed reverse voltage or a second power supply signal providing a stepped reverse voltage to the power supply 204 based on the determination result. For example, the processing unit can determine the position of the wafer pin 202 using optical sensors, electrical sensors, or mechanical sensors. The processing unit sends a first power supply signal providing a fixed reverse voltage or a second power supply signal providing a stepped reverse voltage to the power supply 204 based on the judgment result. The basic process can be referred to in Embodiment 1.

[0064] The fixed reverse voltage provided by the power supply 204 to the wafer 203 via the electrostatic chuck 200 is between 800 volts and 1200 volts. For example, the fixed reverse voltage can be 900 volts, 1000 volts, 1100 volts, etc.

[0065] The predetermined time period is between 15 and 30 seconds. The device in this embodiment can avoid the problem that although the wafer 203 can be lifted, the lifting time is too long, which causes the machine to alarm and reduces the machine's available time.

[0066] Optionally, the step reverse voltage provided by the power supply 204 to the wafer 203 via the electrostatic chuck 200 increases by an increment between 400 volts and 600 volts. For example, the voltage increment of each step reverse voltage increase can be 400 volts, 450 volts, 500 volts, 550 volts, 600 volts, etc., and the step reverse voltage does not exceed the maximum output voltage of the power supply 204. Before applying the step reverse voltage, a fixed reverse voltage can be applied 1 to 3 times to further ensure electrostatic discharge.

[0067] The electrostatic discharge device of the electrostatic chuck 200 also includes an alarm, which is used to issue an alarm when the power supply 204 provides a stepped reverse voltage to the wafer 203 through the electrostatic chuck 200 to reach the maximum output voltage of the power supply 204, if the wafer pin 202 has not yet reached the pre-desorption position H1.

[0068] This invention effectively solves the problem of electrostatic residue on the wafer 203 after etching in the process cavity by setting a reverse voltage applied to the electrostatic chuck 200 and a stepped increase in the reverse voltage. This effectively reduces the risk of the wafer 203 shifting during transport and being broken by the wafer pin 202 due to electrostatic adsorption. Simultaneously, by increasing the judgment time for the wafer pin 202 to rise to the pre-desorption position H1, this invention effectively reduces machine alarms caused by electrostatic adsorption, improves machine availability, and reduces component replacement costs.

[0069] As described above, the electrostatic discharge method and apparatus of the electrostatic chuck 200 of the present invention have the following beneficial effects:

[0070] 1) By setting the reverse voltage applied to the electrostatic chuck 200 and the stepped reverse voltage, the present invention can effectively solve the problem of electrostatic residue on the wafer 203 after etching in the process cavity, and can effectively reduce the risk of the wafer 203 shifting during transport and being broken by the wafer pin 202 due to electrostatic adsorption.

[0071] 2) By increasing the judgment time of the wafer pin 202 to the pre-de-adsorption position H1, the present invention can effectively reduce the alarm of the machine caused by electrostatic adsorption, improve the availability of the machine, and reduce the cost of parts replacement.

[0072] 3) The method and apparatus of the present invention are simple and can effectively reduce wafer 203 transfer abnormalities and breakage caused by poor electrostatic discharge, and extend the service life of ceramic chuck 201. It has broad application prospects in the field of semiconductor integrated circuit manufacturing.

[0073] Therefore, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0074] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for electrostatic discharge from an electrostatic chuck, characterized in that, The electrostatic discharge method includes: Step S1: Apply a first reverse voltage to the wafer using an electrostatic chuck to release the static electricity on the wafer adsorbed by the electrostatic chuck for the first time, and activate the wafer pin of the electrostatic chuck to lift the wafer. Step S2: Determine whether the wafer pin has reached the pre-desorption position within the first time period; if not, proceed to step S3; if yes, proceed to step S6. Step S3: Apply a second reverse voltage to the wafer using an electrostatic chuck to release the static electricity on the wafer adsorbed by the electrostatic chuck for the second time, and activate the wafer pin of the electrostatic chuck to lift the wafer. Step S4: Determine whether the wafer pin has reached the pre-desorption position within the second time period; if not, proceed to step S5; if yes, proceed to step S6. Step S5: Apply a step-increasing third reverse voltage to the wafer to the maximum output voltage of the power supply through an electrostatic chuck, and determine whether the wafer pins have reached the pre-de-adhesion position during the voltage increase. If yes, proceed to step S6; otherwise, proceed to step S7. Step S6: The wafer pin lifts the wafer to the target position; Step S7, machine alarm; wherein, In step S5, after applying the third reverse voltage of each step to the wafer via the electrostatic chuck, the wafer pin of the electrostatic chuck is activated to lift the wafer and it is determined whether the wafer pin reaches the pre-de-adsorption position within the third time period. If yes, the power supply to the electrostatic chuck is stopped; if no, the voltage applied to the wafer via the electrostatic chuck is increased.

2. The electrostatic discharge method for the electrostatic chuck according to claim 1, characterized in that: The first reverse voltage ranges from 800 volts to 1200 volts, and the first time period ranges from 15 seconds to 30 seconds.

3. The electrostatic discharge method for the electrostatic chuck according to claim 1, characterized in that: The second reverse voltage ranges from 800 volts to 1200 volts, and the second time period ranges from 15 seconds to 30 seconds.

4. The electrostatic discharge method for the electrostatic chuck according to claim 1, characterized in that: The voltage increase of the third reverse voltage is between 400 volts and 600 volts each time, and the third reverse voltage is not greater than the maximum output voltage of the power supply.

5. The electrostatic discharge method for the electrostatic chuck according to claim 1, characterized in that: The height of the pre-desorption position is between 1 / 50 and 1 / 2 of the height of the target position.

6. The electrostatic discharge method for the electrostatic chuck according to claim 1, characterized in that: The third time period is between 15 and 30 seconds.

7. An electrostatic discharge device for an electrostatic chuck, characterized in that, For implementing the electrostatic discharge method of the electrostatic chuck as described in any one of claims 1-6, the electrostatic discharge device of the electrostatic chuck comprises: An electrostatic chuck is used to pick up a wafer, and the electrostatic chuck is provided with a wafer pin, which is used to lift the wafer. The electrostatic chuck is equipped with a power supply for providing a fixed reverse voltage to the wafer upon receiving a first power supply signal, and for providing a stepped reverse voltage to the wafer upon receiving a second power supply signal; and The processing unit is connected to the electrostatic chuck and the power supply, and is used to determine whether the wafer pin has reached the pre-de-adsorption position within a predetermined time period after the wafer pin is started to lift the wafer, and to send a first power supply signal providing a fixed reverse voltage or a second power supply signal providing a stepped increasing reverse voltage to the power supply according to the determination result.

8. The electrostatic discharge device for the electrostatic chuck according to claim 7, characterized in that: The wafer lifting position of the wafer pin of the electrostatic chuck includes a pre-de-adsorption position and a target position. The target position is higher than the pre-de-adsorption position, and the height of the pre-de-adsorption position is between 1 / 50 and 1 / 2 of the height of the target position.

9. The electrostatic discharge device for the electrostatic chuck according to claim 7, characterized in that: The power supply provides a fixed reverse voltage to the wafer via the electrostatic chuck, ranging from 800 volts to 1200 volts.

10. The electrostatic discharge device for the electrostatic chuck according to claim 7, characterized in that: The predetermined time period is between 15 seconds and 30 seconds.

11. The electrostatic discharge device for the electrostatic chuck according to claim 7, characterized in that: The step reverse voltage provided by the power supply to the wafer via the electrostatic chuck increases by 400 volts to 600 volts with each increment, and the step reverse voltage is not greater than the maximum output voltage of the power supply.

12. The electrostatic discharge device for the electrostatic chuck according to claim 7, characterized in that: It also includes an alarm that is used to sound an alarm if the wafer pin has not reached the pre-de-adsorption position when the power supply provides a stepped reverse voltage to the wafer through the electrostatic chuck to the maximum output voltage of the power supply.

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