Electrostatic chucks and semiconductor process equipment

Abstract

This invention provides an electrostatic chuck and semiconductor processing equipment. The electrostatic chuck includes a chuck body, an adsorption electrode, a shielding structure, a sensing electrode, and an electrostatic detection device. The adsorption electrode has a cutout portion; the shielding structure is disposed within the chuck body and grounded; the shielding structure has a shielding space inside to shield the electric field generated by the adsorption electrode, and the shielding space is located below the cutout portion; the shielding structure has an opening on the side facing the cutout portion to allow the electric field generated by the wafer carried by the chuck body to enter the shielding space; the sensing electrode is disposed within the shielding space; the sensing electrode is used to couple with the wafer to generate an induced voltage through electrostatic induction; the electrostatic detection device is used to detect the induced voltage of the sensing electrode to achieve non-contact detection of the wafer's voltage to ground.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor equipment, specifically relating to an electrostatic chuck and semiconductor process equipment. Background Technology

[0002] In the semiconductor industry, electrostatic chucks are used in vacuum chambers, primarily utilizing the electrostatic force generated by their internal adsorption electrodes to hold wafers in place. This is one of the most important methods for wafer holding. Compared to other wafer-fixing structures, electrostatic chucks also offer heating, temperature control, and RF power loading functions. Due to their excellent stability, low particle count, and temperature control, electrostatic chucks are more widely used in the semiconductor field.

[0003] In plasma processing, plasma generates a DC self-bias voltage, and some processes require the detection of this self-bias voltage. Therefore, electrostatic chucks typically include an electrostatic detection device to detect the plasma bias voltage of the wafer. Specifically, the detection end of the electrostatic detection device is inserted into the electrostatic chuck and detects the wafer voltage by contacting the wafer surface, thereby indirectly detecting the bias voltage generated by the plasma above the wafer. However, installing the electrostatic detection device within the electrostatic chuck during manufacturing is technically challenging and prone to leakage. Furthermore, existing electrostatic detection devices generally only detect silicon wafers with low resistivity and have difficulty detecting silicon oxide wafers with high resistivity. Summary of the Invention

[0004] The present invention aims to solve the problems of high manufacturing difficulty, leakage risk and unsuitability for various types of wafers in existing electrostatic chucks, and provides an electrostatic chuck.

[0005] This invention provides an electrostatic chuck, including a chuck body and an adsorption electrode; it also includes a shielding structure, an induction electrode, and an electrostatic detection device; wherein the adsorption electrode has a hollow portion;

[0006] The shielding structure is disposed in the chuck body and grounded; the shielding structure has a shielding space inside for shielding the electric field generated by the adsorption electrode, and the shielding space is located below the hollow part; the shielding structure has an opening on the side facing the hollow part so that the electric field generated by the wafer carried by the chuck body can enter the shielding space;

[0007] The sensing electrode is disposed within the shielding space; the sensing electrode is used to couple with the wafer to generate an induced voltage through electrostatic induction with the wafer.

[0008] The electrostatic detection device is used to detect the induced voltage of the induction electrode.

[0009] Optionally, the electrostatic detection device includes:

[0010] A first power supply has an output terminal and a ground terminal; the output terminal of the first power supply is electrically connected to the sensing electrode; the first power supply is used to output voltage to the sensing electrode.

[0011] A current detection unit is connected in series between the first power supply and the sensing electrode to detect the actual current value in the electrostatic detection device.

[0012] A first control unit is configured to control the first power supply to adjust the output voltage according to the actual current value, so as to reduce the actual current value to 0A;

[0013] A voltage acquisition unit is used to acquire the voltage to ground at the output terminal of the first power supply when the actual current value is 0A, so as to obtain the induced voltage of the sensing electrode.

[0014] Optionally, the sensing electrode may be movably disposed inside the shielding space;

[0015] The electrostatic detection device further includes a drive assembly that is connected to the sensing electrode for driving the sensing electrode to move in the shielded space, so as to change the value of the capacitance formed by the sensing electrode and the chuck body.

[0016] Optionally, the shielding structure includes:

[0017] A first shielding ring is disposed within the shielding space and surrounds the sensing electrode; the first shielding ring is grounded.

[0018] Optionally, the shielding structure includes:

[0019] The second shielding ring is located between the shielding space and the chuck body and is arranged around the periphery of the shielding space; the second shielding ring is grounded.

[0020] Optionally, the shielding structure includes:

[0021] The second shielding ring is located between the shielding space and the chuck body and is arranged around the periphery of the shielding space;

[0022] A conductive element is embedded inside the chuck body; the conductive element is electrically connected to the first shielding ring and the second shielding ring respectively, so that the second shielding ring is grounded through the first shielding ring.

[0023] Optionally, the adsorption electrode includes two sub-electrode sheets spaced apart; the hollow portion is disposed at the interval between the two sub-electrode sheets.

[0024] Optionally, the electrostatic chuck further includes:

[0025] The second power source is electrically connected to each of the two sub-electrode plates, and is used to provide positive and negative voltages to the two sub-electrode plates respectively:

[0026] The second control unit is communicatively connected to the second power supply and the electrostatic detection device, respectively. The second control unit is used to adjust the positive voltage and negative voltage supplied to the two sub-electrode plates according to the voltage value detected by the electrostatic detection device, so that the absolute value of the voltage difference between the two sub-electrode plates and the wafer is the same.

[0027] Optionally, the electrostatic chuck further includes:

[0028] A sealing flange is disposed below the chuck body and is sealed to the lower surface of the chuck body;

[0029] The driving component includes:

[0030] The power source is located outside the chuck body;

[0031] A drive shaft is movably inserted into the sealing flange; one end of the drive shaft extends into the shielding space and is fixedly connected to the induction electrode, and the other end of the drive shaft extends to the outside of the shielding space and is connected to the power source.

[0032] Optionally, the chuck body is provided with a plurality of support protrusions, which are used to jointly support the wafer;

[0033] The power source is used to drive the drive shaft to rotate around its own axis; the drive shaft is arranged parallel to the axis of the chuck body, and the projection of the sensing electrode on the horizontal plane overlaps with the projection of the support protrusion on the horizontal plane, so as to change the dielectric constant between the sensing electrode and the wafer during rotation.

[0034] Optionally, the power source is used to drive the drive shaft to translate along its own axis, so as to change the spacing between the sensing electrode and the wafer during the translation.

[0035] Optionally, the drive shaft is made of a conductive material;

[0036] The electrostatic detection device uses a brush structure to connect to the outer peripheral surface of the drive shaft for electrical connection.

[0037] As another technical solution, the present invention also provides a semiconductor process apparatus, which includes a process chamber and an electrostatic chuck as described above; wherein the electrostatic chuck is disposed inside the process chamber and is used to carry wafers for semiconductor processing.

[0038] The present invention has the following beneficial effects:

[0039] The electrostatic chuck provided in this embodiment of the invention enables non-contact detection of the wafer's voltage to ground by utilizing the electrostatic induction phenomenon between the sensing electrode and the wafer, without direct contact with the wafer. Therefore, the sensing electrode can be disposed in a shielded space spaced apart from the chuck's main bearing surface, without penetrating the chuck body, thereby reducing the manufacturing difficulty of the electrostatic chuck and avoiding the problem of air leakage. Furthermore, since the electrostatic chuck proposed in this embodiment enables non-contact detection, the resistivity of the wafer's backside material does not affect the electrostatic detection results. Consequently, the electrostatic chuck proposed in this embodiment can be applied to support various types of wafers. Attached Figure Description

[0040] Figure 1 This is a simplified structural diagram of the electrostatic chuck in the relevant technical solution;

[0041] Figure 2A A top view of an electrostatic chuck provided in an embodiment of the present invention;

[0042] Figure 2B for Figure 2A Cross-sectional view along the AA' direction;

[0043] Figure 2C for Figure 2A A partial cross-sectional view along the BB' direction;

[0044] Figure 3 This is a circuit equivalent diagram of the electrostatic detection device provided in an embodiment of the present invention;

[0045] Figure 4 This is a schematic diagram illustrating the working principle of the sensing electrode and driving assembly provided in an embodiment of the present invention.

[0046] Figure 5 This is a simplified structural diagram of the connection between the drive shaft and the first power source provided in an embodiment of the present invention;

[0047] Figure 6 This is a simplified structural diagram of an electrostatic chuck provided in an embodiment of the present invention during operation;

[0048] Figure 7 This is a simplified diagram of another structure of the electrostatic chuck provided in an embodiment of the present invention during operation. Detailed Implementation

[0049] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0050] It is understood that the specific embodiments and accompanying drawings described herein are merely for explaining the invention and are not intended to limit the invention.

[0051] It is understood that, without conflict, the various embodiments of the present invention and the features thereof can be combined with each other.

[0052] It is understood that, for ease of description, the accompanying drawings of this invention only show the parts related to the embodiments of this invention, while the parts unrelated to the embodiments of this invention are not shown in the drawings.

[0053] It is understood that, without conflict, the functions and steps marked in the flowcharts and block diagrams of the embodiments of the present invention may occur in a different order than that marked in the accompanying drawings.

[0054] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

[0055] like Figure 1 As shown, in related technologies, an electrostatic chuck typically consists of a ceramic disk body 01, an electrode structure 02, and a support bump structure 03. The support bump structure 03 is disposed on the surface of the ceramic disk body 01 to support the wafer 04 placed on the electrostatic chuck. The electrode structure 02 is embedded inside the ceramic disk body 01 and is used to attract the wafer 04 using electrostatic induction after being powered on, thereby fixing the wafer 04. Figure 1 Taking the bipolar electrostatic chuck shown as an example, its process of adsorbing wafer 04 is as follows: positive and negative voltages are applied to the left and right electrode structures 02 respectively, so that the lower surface of wafer 04 is polarized and negative and positive charges accumulate in the regions corresponding to the two electrode structures 02 respectively, thereby generating an electrostatic induction force for mutual adsorption with the corresponding electrode structures 02; as shown Figure 1As shown, when a bipolar electrostatic chuck is applied to a process involving plasma, when the process gas inside the chamber is excited into plasma, the plasma cluster above wafer 04 generates a self-bias voltage. This bias voltage is directly applied to wafer 04, resulting in an inconsistency in the number of positive and negative charges in the regions corresponding to the two electrode structures 02 on wafer 04. For example, if the plasma is positively charged after ignition, the positive charge in one region of wafer 04 will increase while the negative charge in another region will decrease. In this case, the voltage difference between the two electrode structures 02 and wafer 04 will also change, leading to an increase in the adsorption force of one electrode structure 02 on wafer 04 and a decrease in the adsorption force of the other electrode structure 02 on wafer 04. This results in an overall force imbalance on wafer 04, and may even cause the adsorption force of one electrode structure 02 on wafer 04 to be zero.

[0056] However, as Figure 1 As shown, the ceramic disk body 01 typically also has a back-blowing air channel 011 inside, which is used to blow back-blowing gas onto the lower surface of the wafer 04 during the process. If the wafer 04 experiences an imbalance in the adsorption force due to plasma excitation, its position may shift, leading to uneven back-blowing airflow and an inability to maintain back-blowing pressure. This uneven force may also cause the wafer 04 to detach from the ceramic disk body 01, all of which would prevent the process from proceeding normally. To avoid these problems, relevant technical solutions typically monitor the plasma self-bias value to ensure the adsorption stability of the bipolar electrostatic chuck. Specifically, as... Figure 1 As shown, in the related technology, a plasma bias detection structure 05 is also provided inside the ceramic disk body 01. The plasma bias detection structure 05 includes an electrostatic detection bump 051 formed on the surface of the ceramic disk body 01, a wiring structure 052 that runs through the ceramic disk body 01, and a voltmeter 053 disposed outside the ceramic disk body 01. The voltmeter 053 is electrically connected to the electrostatic detection bump 051 through the wiring structure 052, so that when the plasma is ignited, after the plasma bias is applied to the wafer 04, the voltage of the wafer 04 to ground is detected, thereby indirectly detecting the plasma bias.

[0057] However, since the trace structure 052 of the plasma bias detection structure 05 needs to penetrate the ceramic disk body 01, the manufacturing process of the trace structure 052 is quite difficult, and it is prone to leakage problems due to damage to the sealing of the electrostatic chuck, thus reducing the yield of the electrostatic chuck. Furthermore, the electrostatic detection bump 051 needs to be made of conductive material, while the supporting bump structure 03 needs to be made of insulating material. Therefore, the electrostatic detection bump 051 needs to be manufactured by a separate process, which increases the manufacturing cost of the electrostatic chuck. Moreover, the detection principle of the plasma bias detection structure 05 is to detect the voltage of the wafer 04 to ground by connecting the voltmeter 053 in parallel between the wafer 04 and the ground line. However, if the resistance of the wafer material is extremely high, the internal resistance of the voltmeter 053 may be less than the resistance of the wafer 04 itself, resulting in a lower voltage division by the voltmeter 053 and reduced accuracy of the measurement results. Therefore, the plasma bias detection structure in the relevant technology is only suitable for processing silicon wafers. However, when detecting wafers with silicon oxide as the surface material, the high insulation of silicon oxide will lead to inaccurate detection of the wafer-to-ground voltage value.

[0058] It is evident that electrostatic chucks in related technologies suffer from problems such as high processing difficulty, high manufacturing cost, risk of air leakage, and inability to be widely applied to various types of wafers.

[0059] To address the aforementioned technical problems, this embodiment provides an electrostatic chuck that can be applied in semiconductor process equipment and used to fix wafers. For example... Figure 2A As shown, the electrostatic chuck includes a chuck body 1 and an adsorption electrode 2. Specifically, the chuck body 1 has a bearing surface for carrying the wafer 6; the adsorption electrode 2 is disposed inside the chuck body 1, and is used to generate electrostatic force between itself and the wafer 6 when energized to adsorb the wafer 6.

[0060] like Figures 2A to 2B As shown, the electrostatic chuck provided in this embodiment also includes a shielding structure 3, an induction electrode 4, and an electrostatic detection device 5. The adsorption electrode 2 has a cutout portion 21, meaning that there is no adsorption electrode 2 structure in the area corresponding to the cutout portion 21. Therefore, the portion of the wafer 6 corresponding to the cutout portion 21 will not generate electrostatic force interacting with the adsorption electrode 2, nor will it carry a charge due to electrostatic induction with the adsorption electrode 2.

[0061] A shielding structure 3 is disposed within the chuck body 1 and grounded. The shielding structure 3 has a shielding space 31 inside to shield the electric field generated by the adsorption electrode 2. By grounding, the electric field outside the shielding space 31 is shielded, thus preventing the electric field generated by the adsorption electrode 2 after energization from entering the shielding space 31. The shielding space 31 is located below the cutout portion 21. The shielding structure 3 has an opening on the side facing the cutout portion 21 to allow the electric field generated by the wafer 6 to enter the shielding space 31. Thus, the electric field generated by the adsorption electrode 2 will not exist within the shielding space 31, and after plasma excitation, only the electric field generated by the charged wafer 6 will exist within the shielding space 31. Specifically, since the adsorption electrode 2 is disposed inside the chuck body 1, it is spaced apart from the bearing surface of the chuck body 1. Correspondingly, the cutout portion 21 is also spaced apart from the bearing surface. Furthermore, the shielding space 31 located below the cutout portion 21 is also spaced apart from the bearing surface. Therefore, the shielding space 31 does not penetrate the chuck body 1, and the adsorption electrode 2 will not contact the wafer 6.

[0062] The sensing electrode 4 is disposed within the shielding space 31. The sensing electrode 4 is used to couple with the wafer 6 placed on the bearing surface of the chuck body 1 to induce electrostatic induction between them. Under the action of electrostatic induction, the charge inside the sensing electrode 4 is redistributed, thereby generating an induced voltage. This induced voltage corresponds to the voltage of the portion of the wafer 6 located at the cutout portion 21. The electrostatic detection device 5 is used to detect the induced voltage of the sensing electrode 4, thereby obtaining the voltage of the portion of the wafer 6 corresponding to the cutout portion 21. As mentioned above, the portion of the wafer 6 corresponding to the cutout portion 21 does not carry a charge due to electrostatic induction with the adsorption electrode 2. That is, the portion of the wafer 6 corresponding to the cutout portion 21 is only affected by the plasma bias voltage above it. Therefore, the induced voltage detected by the electrostatic detection device 5 can reflect the plasma bias voltage.

[0063] As can be seen, the electrostatic chuck proposed in this embodiment can achieve non-contact detection of the voltage to ground of wafer 6 without direct contact with it. Furthermore, the sensing electrode 4 in this embodiment can be disposed in a shielded space 31 spaced apart from the bearing surface of the chuck body 1, without penetrating the electrostatic chuck body 1. Therefore, compared to the penetrating plasma bias detection structure in related technologies, the electrostatic chuck proposed in this embodiment has a lower manufacturing difficulty and avoids the problem of air leakage. Moreover, since the electrostatic chuck proposed in this embodiment can achieve non-contact detection of the voltage of wafer 6, the resistivity of the material on the back of wafer 6 will not affect the electrostatic detection results. Therefore, the electrostatic chuck proposed in this embodiment can not only detect the voltage to ground of silicon wafers, but also wafers made of insulating materials such as silicon nitride wafers, silicon carbide wafers, and sapphire wafers.

[0064] For example, the structure of the sensing electrode 4 can be a metal sheet.

[0065] For example, the chuck body 1 is made of an insulating ceramic material to form an insulating dielectric between the sensing electrode 4 and the wafer 6.

[0066] In some embodiments, such as Figure 3 As shown, the electrostatic detection device 5 includes a first power supply 51, a current detection unit 52, a first control unit, and a voltage acquisition unit (not shown in the figure). The first power supply 51 has an output terminal and a ground terminal; the output terminal of the first power supply 51 is electrically connected to the sensing electrode 4; the first power supply 51 is used to output voltage to the sensing electrode 4, specifically, the output voltage of the first power supply 51 is variable.

[0067] A current detection unit 52 is connected in series between the first power supply 51 and the sensing electrode 4 to detect the actual current value in the electrostatic detection device 5. A first control unit controls the first power supply 51 to adjust its output voltage based on the actual current value, reducing the actual current value to 0A. A voltage acquisition unit acquires the voltage to ground at the output terminal of the first power supply 51 when the actual current value is 0A, thus obtaining the voltage to ground of the sensing electrode 4 after charging or discharging has stopped.

[0068] Specifically, before the plasma is excited, the adsorption electrode 2 is charged to adsorb the wafer 6, and electrostatic induction occurs on the lower surface of the wafer 6, resulting in a charge. After the plasma is excited, since the plasma located above the wafer 6 remains in contact with the wafer 6, the bias voltage generated by the plasma is directly applied to the wafer 6, that is, making the wafer 6 and the plasma sheath have the same potential; and as Figure 3As shown, since the sensing electrode 4 and the wafer 6 are spaced apart, a capacitor C1 can be formed between the sensing electrode 4 and the wafer 6. The wafer 6 can be considered as one plate of the capacitor C1, and the sensing electrode 4 can be considered as the other plate of the capacitor C1. In the initial detection stage of the electrostatic detection device 5, the sensing electrode 4 is initially uncharged. However, at the instant the wafer 6 becomes charged under the action of plasma, electrostatic induction begins to occur between the sensing electrode 4 and the wafer 6. As a result, the sensing electrode 4 generates an induced charge with the opposite polarity to that of the wafer 6. During the electrostatic induction process, the sensing electrode 4 continuously acquires electrons or holes from the electrostatic detection device 5. Correspondingly, a current is generated in the circuit connecting the first power supply 51 and the current detection unit 52. The first power supply 51 continuously charges or discharges the sensing electrode 4 until the current detection unit 52 detects a current value of 0A, which means that the sensing electrode has been charged. When the sensing electrode 4 stops charging or discharging, it also means that electrostatic induction between the sensing electrode 4 and the wafer 6 stops, that is, the potential difference between the sensing electrode 4 and the wafer 6 is 0. At this time, the voltage to ground of the sensing electrode 4 detected by the voltage acquisition unit is the voltage to ground of the wafer 6, that is, the voltage to ground of the portion of the wafer 6 corresponding to the cutout portion 21. As mentioned above, since the portion of the wafer 6 corresponding to the cutout portion 21 is not affected by the voltage of the adsorption electrode 2, the voltage value detected by the voltage acquisition unit is also the plasma bias voltage to ground.

[0069] For example, during the detection process of the electrostatic discharge detection device 5, the first control unit can control the output voltage value of the first power supply 51 to continuously increase from a preset initial value until the current detection unit 52 detects a current value of 0A. The preset initial value is, for example, 0V.

[0070] For example, the current detection unit 52 can be a precision ammeter with high detection accuracy to ensure that the ammeter reading can accurately reflect the current in the circuit connecting the first power supply 51 and the current detection unit 52.

[0071] In some embodiments, the sensing electrode 4 is movably disposed within the shielding space 31. Furthermore, as... Figure 2BAs shown, the electrostatic detection device 5 also includes a drive assembly 53; the drive assembly 53 is connected to the sensing electrode 4 and is used to drive the sensing electrode 4 to move within the shielded space 31. According to the capacitance formula C = εS / 4πkd, where ε is the dielectric constant, S is the plate area, d is the plate spacing, and k is the electrostatic constant, the dielectric constant ε and the plate spacing d are the main factors affecting the capacitance. Therefore, when the sensing electrode 4 rotates horizontally or moves vertically under the drive of the drive assembly 53, it will correspondingly change the dielectric constant ε or the plate spacing d between the sensing electrode 4 and the electrostatic chuck, thereby changing the capacitance formed between the sensing electrode 4 and the wafer 6. According to the charging and discharging principle of a capacitor: C = Q / U, when there is a voltage difference between the capacitor plates, the capacitor will continuously charge and discharge as the capacitance changes, causing the current value detected by the current detection unit 52 to continuously change. When the voltage difference between the capacitor plates is 0V, the capacitor will stop charging and discharging. That is to say, when the voltage difference between the capacitor plates is 0V, the capacitor will no longer charge or discharge, regardless of how its capacitance value changes. Therefore, by continuously changing the capacitance formed between the sensing electrode 4 and the wafer 6, it can be ensured that when the current value detected by the current detection unit 52 is 0A, the voltage of the sensing electrode 4 is completely consistent with the voltage of the wafer 6. This improves the accuracy of voltage detection of the wafer 6 and avoids detection errors caused by incomplete charging or discharging of the capacitor.

[0072] For example, the voltage acquisition unit continuously monitors the induced voltage of the sensing electrode 4 during the process; moreover, the driving component 53 can be turned on at the beginning of the process stage and continuously drive the sensing electrode 4 during the process, thereby enabling the monitoring of the induced voltage of the sensing electrode 4 during the process and thus timely acquisition of the plasma bias voltage to ground.

[0073] In some embodiments, the electrostatic chuck further includes a sealing flange 11, disposed below the chuck body 1 and sealed to the lower surface of the chuck body 1, to seal the back side of the electrostatic chuck. The drive assembly 53 includes a power source 531 and a drive shaft 532. The power source 531 is disposed outside the chuck body 1. The drive shaft 532 is movably inserted into the sealing flange 11; one end of the drive shaft 532 extends into the shielding space 31 and is fixedly connected to the induction electrode 4, while the other end of the drive shaft 532 extends outside the shielding space 31 and is driveably connected to the power source 531.

[0074] In some specific embodiments, such as Figure 2C As shown, the chuck body 1 is provided with multiple support protrusions 12, which are used to jointly support the wafer 6. In other words, the top surfaces of the multiple support protrusions 12 together constitute the bearing surface of the chuck body 1. Figure 4As shown, the power source 531 drives the transmission shaft 532 to rotate around its own axis. The transmission shaft 532 is arranged parallel to the axis of the chuck body 1, and the projection of the sensing electrode 4 on the horizontal plane partially overlaps with the projection of the support protrusion 12 on the horizontal plane. Thus, during rotation, when the sensing electrode 4 rotates until its projection on the horizontal plane does not overlap with the support protrusion 12, the medium between the sensing electrode 4 and the wafer 6 consists only of the chuck body 1 and the vacuum medium; when the sensing electrode 4 rotates until its projection on the horizontal plane overlaps with the support protrusion 12, the medium between the sensing electrode 4 and the wafer 6 consists of the chuck body 1, the support protrusion 12, and the vacuum medium. Therefore, as the sensing electrode 4 rotates, the medium between the sensing electrode 4 and the wafer 6 is constantly changing, and correspondingly, the dielectric constant ε is also constantly changing, thereby causing the capacitance value formed between the wafer 6 and the sensing electrode 4 to continuously change.

[0075] For example, the power source 531 can be a rotary motor, and the power output end of the rotary motor can be connected to the drive shaft 532 by a belt to drive the drive shaft 532 to rotate.

[0076] For example, such as Figure 5 As shown, the drive assembly 53 also includes a plurality of transmission bearings disposed outside the shielding space 31. The transmission bearings are connected to the outer periphery of the transmission shaft 532 and are used to support the rotation of the transmission shaft 532.

[0077] For example, the power source 531 drives the transmission shaft 532 to rotate so that the capacitor formed between the wafer 6 and the sensing electrode 4 oscillates uniformly, thereby ensuring the consistency of the response time of the electrostatic detection device 5 in multiple detection processes; for example, the oscillation frequency can be 50Hz.

[0078] In some embodiments, the power source 531 is used to drive the transmission shaft 532 to translate along its own axis, so that the distance between the sensing electrode 4 and the bearing surface changes during the translation process, thereby causing the value of the capacitance formed between the wafer 6 and the sensing electrode 4 to change continuously.

[0079] In some embodiments, the drive shaft 532 is made of a conductive material, such as a metal. The first power supply 51 uses a brush structure 533 to contact the outer peripheral surface of the drive shaft 532 to maintain electrical connection with the drive shaft 532 and to avoid hindering the movement of the drive shaft 532.

[0080] In some embodiments, the shielding structure 3 includes a first shielding ring 32; the first shielding ring 32 is located within the shielding space 31 and surrounds the sensing electrode 4. The first shielding ring 32 is grounded to shield the electric field located around the sensing electrode 4, i.e., the electric field generated by the adsorption electrode 2, and the central hole of the first shielding ring 32 allows the electric field generated between the sensing electrode 4 and the wafer 6 to pass through, thereby preventing the peripheral electric field from interfering with the detection results of the electrostatic detection device 5. Moreover, during the movement of the sensing electrode 4 in the shielding space 31, the first shielding ring 32 can keep the direct distance between the sensing electrode 4 and the ground wire constant, so that the capacitance C2 of the sensing electrode 4 to ground remains constant, thereby preventing changes in the voltage division of the capacitance C2 of the sensing electrode 4 to ground, which would lead to inaccurate detection results of the electrostatic detection device 5. It is easy to understand that the size of the first shielding ring 32 is such that the movement of the sensing electrode 4 is not interfered with.

[0081] For example, the shielding space 31 can be a blind hole machined on the back side of the chuck body 1. It can be formed by drilling or milling directly on the back side of the chuck body 1, or it can be integrally formed during the sintering process of the chuck body 1. Such a machining process has low precision requirements and is easy to machine. Moreover, the first shielding ring 32 can be a metal plating formed on the inner peripheral wall of the blind hole.

[0082] For example, the shielding space 31 may be cylindrical.

[0083] In some embodiments, the shielding structure 3 further includes a second shielding ring 33. The second shielding ring 33 is located between the shielding space 31 and the chuck body 1 and is disposed around the periphery of the shielding space 31. The second shielding ring 33 is grounded to shield the electric field located obliquely above the sensing electrode 4, namely the electric field generated by the adsorption electrode 2 and the electric field generated by the wafer due to the adsorption electrode 2, thereby avoiding interference of the peripheral electric field with the detection results of the electrostatic detection device 5.

[0084] For example, the second shielding ring 33 can be disposed in the same layer as the adsorption electrode 2, that is, the distance between the second shielding ring 33 and the bearing surface is equal to the distance between the adsorption electrode 2 and the bearing surface, so as to be flush with the adsorption electrode 2, thereby shielding the electric field generated by the adsorption electrode 2 located on its periphery as much as possible.

[0085] Furthermore, in some embodiments, such as Figure 2B As shown, the shielding structure 3 also includes a conductive element 34 embedded inside the chuck body 1. The conductive element 34 is electrically connected to the first shielding ring 32 and the second shielding ring 33 respectively, so that the second shielding ring 33 can be grounded through the first shielding ring 32, thereby simplifying the structure.

[0086] For example, the conductive element 34 described above can be made of metal material, and its shape can be filament, sheet, etc.

[0087] For example, the first shielding ring 32 and the second shielding ring 33 can also be connected as one unit.

[0088] For example, the first shielding ring 32, the second shielding ring 33, and the conductive element 34 can all be manufactured using a printing and sintering process. Preferably, the first shielding ring 32, the second shielding ring 33, and the conductive element 34 can be made of the same metal material to save the metal printing and molding steps.

[0089] In some embodiments, the adsorption electrode 2 includes two spaced-apart sub-electrode plates 22, i.e., the electrostatic chuck is a bipolar electrostatic chuck. Specifically, when the two sub-electrode plates 22 are respectively applied with positive and negative voltages, the lower surface of the wafer will be polarized to generate opposite charges in the regions corresponding to the two sub-electrode plates 22. That is, the region of the wafer 6 with the sub-electrode plate 22 with positive voltage will generate negative charge, and the region with the sub-electrode plate 22 with negative voltage will generate positive charge. The cutout portion 21 is provided at the interval between the two sub-electrode plates 22 to avoid the two sub-electrode plates, thereby avoiding the portion of the wafer that generates charge due to polarization, and can avoid interfering with the adsorption effect of the two sub-electrode plates 22 on the wafer 6. Furthermore, the two sub-electrode plates 22 of the bipolar electrostatic chuck are usually arranged symmetrically about the diameter of the electrostatic chuck, and the cutout portion 21 is arranged at the interval between the two sub-electrode plates 22 so that the detected part of the wafer 6 is as close as possible to the center of the electrostatic chuck, so as to be as opposite as possible to the center region of the plasma, thereby making the detection result of the electrostatic detection device 5 reflect the ground bias voltage of the plasma as accurately as possible.

[0090] It should be noted that this application does not limit the type of electrostatic chuck, which can also be a bipolar electrostatic chuck or a JR type electrostatic chuck.

[0091] For example, such as Figure 2C As shown, a purge air channel 13 is provided at the center of the chuck body 1, and the outlet of the purge air channel 13 is located at the center of the bearing surface; correspondingly, a purge air hole 23 is provided at the center of the adsorption electrode 2 to allow purge gas to pass through, thereby making the purge airflow evenly distributed between the bearing surface and the wafer, so as to achieve uniform heating between the electrostatic chuck and the wafer by using the purge airflow.

[0092] For example, the chuck body 1 is also provided with a liftable pin mechanism (PIN) to push the wafer up and down; correspondingly, the adsorption electrode 2 is provided with a pin hole 24 for the corresponding pin mechanism to pass through.

[0093] In some embodiments, such as Figure 6 and Figure 7As shown, the electrostatic chuck also includes a second power supply 7 and a second control unit. Specifically, the second power supply 7 is electrically connected to the two sub-electrode plates 22 respectively, and is used to provide positive and negative voltages to the two sub-electrode plates 22. The second control unit is communicatively connected to the second power supply 7 and the electrostatic detection device 5 respectively; the second control unit is used to adjust the positive and negative voltages provided to the two sub-electrode plates 22 according to the detected voltage value to ground, so that the absolute value of the voltage difference between the two sub-electrode plates 22 and the wafer 6 is the same; since the voltage difference is proportional to the adsorption force, when the plasma bias causes uneven charge distribution on the lower surface of the wafer 6, by adjusting the positive and negative voltages applied to the two sub-electrode plates 22 respectively, the adsorption force of the sub-electrode plates 22 on the wafer 6 can be made consistent, so that the wafer 6 is subjected to uniform force, thereby avoiding uneven back-blowing airflow and preventing the wafer 6 from detaching from the electrostatic chuck, ensuring the normal operation of the process.

[0094] As another technical solution, this embodiment provides a semiconductor process apparatus, which includes a process chamber and an electrostatic chuck as described above; wherein, the electrostatic chuck is disposed inside the process chamber for carrying a wafer for semiconductor processes, such as plasma processing. Furthermore, during the process execution phase, the electrostatic electrode device in the electrostatic chuck can detect the voltage on the wafer, thereby indirectly monitoring the bias voltage generated by the plasma above the wafer.

[0095] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. An electrostatic chuck, comprising a chuck body and an adsorption electrode; characterized in that, It also includes a shielding structure, induction electrodes, and an electrostatic detection device: among which, The adsorption electrode has a hollow portion; The shielding structure is disposed in the chuck body and grounded; the shielding structure has a shielding space inside for shielding the electric field generated by the adsorption electrode, and the shielding space is located below the hollow part; the shielding structure has an opening on the side facing the hollow part so that the electric field generated by the wafer carried by the chuck body can enter the shielding space; The sensing electrode is disposed within the shielding space; the sensing electrode is used to couple with the wafer to generate an induced voltage through electrostatic induction with the wafer. The electrostatic detection device is used to detect the induced voltage of the induction electrode.

2. The electrostatic chuck according to claim 1, characterized in that, The electrostatic detection device includes: A first power supply has an output terminal and a ground terminal; the output terminal of the first power supply is electrically connected to the sensing electrode; the first power supply is used to output voltage to the sensing electrode. A current detection unit is connected in series between the first power supply and the sensing electrode to detect the actual current value in the electrostatic detection device. A first control unit is configured to control the first power supply to adjust the output voltage according to the actual current value, so as to reduce the actual current value to 0A; A voltage acquisition unit is used to acquire the voltage to ground at the output terminal of the first power supply when the actual current value is 0A, so as to obtain the induced voltage of the sensing electrode.

3. The electrostatic chuck according to claim 2, characterized in that, The sensing electrode is movably disposed inside the shielding space; The electrostatic detection device further includes a drive assembly that is connected to the sensing electrode for driving the sensing electrode to move in the shielded space, so as to change the value of the capacitance formed by the sensing electrode and the chuck body.

4. The electrostatic chuck according to claim 1, characterized in that, The shielding structure includes: A first shielding ring is disposed within the shielding space and surrounds the sensing electrode; the first shielding ring is grounded.

5. The electrostatic chuck according to claim 1, characterized in that, The shielding structure includes: The second shielding ring is located between the shielding space and the chuck body and is arranged around the periphery of the shielding space; the second shielding ring is grounded.

6. The electrostatic chuck according to claim 4, characterized in that, The shielding structure includes: The second shielding ring is located between the shielding space and the chuck body and is arranged around the periphery of the shielding space; A conductive element is embedded inside the chuck body; the conductive element is electrically connected to the first shielding ring and the second shielding ring respectively, so that the second shielding ring is grounded through the first shielding ring.

7. The electrostatic chuck according to claim 1, characterized in that, The adsorption electrode includes two sub-electrode plates spaced apart; the hollow portion is disposed at the interval between the two sub-electrode plates.

8. The electrostatic chuck according to claim 7, characterized in that, The electrostatic chuck also includes: The second power source is electrically connected to each of the two sub-electrode plates, and is used to provide positive and negative voltages to the two sub-electrode plates respectively: The second control unit is communicatively connected to the second power supply and the electrostatic detection device, respectively. The second control unit is used to adjust the positive voltage and negative voltage supplied to the two sub-electrode plates according to the voltage value detected by the electrostatic detection device, so that the absolute value of the voltage difference between the two sub-electrode plates and the wafer is the same.

9. The electrostatic chuck according to claim 3, characterized in that, The electrostatic chuck also includes: A sealing flange is disposed below the chuck body and is sealed to the lower surface of the chuck body; The driving component includes: The power source is located outside the chuck body; A drive shaft is movably inserted into the sealing flange; one end of the drive shaft extends into the shielding space and is fixedly connected to the induction electrode, and the other end of the drive shaft extends to the outside of the shielding space and is connected to the power source.

10. The electrostatic chuck according to claim 9, characterized in that, The chuck body is provided with multiple support protrusions, which are used to jointly support the wafer; The power source is used to drive the drive shaft to rotate around its own axis; the drive shaft is arranged parallel to the axis of the chuck body, and the projection of the sensing electrode on the horizontal plane overlaps with the projection of the support protrusion on the horizontal plane, so as to change the dielectric constant between the sensing electrode and the wafer during rotation.

11. The electrostatic chuck according to claim 9, characterized in that, The power source is used to drive the transmission shaft to translate along its own axis, so as to change the spacing between the sensing electrode and the wafer during the translation process.

12. The electrostatic chuck according to claim 9, characterized in that, The drive shaft is made of a conductive material; The first power source is connected to the outer peripheral surface of the drive shaft using a brush structure for electrical connection.

13. A semiconductor process apparatus, characterized in that, Includes a process chamber and an electrostatic chuck as described in any one of claims 1-12; wherein, The electrostatic chuck is disposed inside the process chamber and is used to carry the wafer for semiconductor processing.

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