Electrostatic chuck device and method for shortening desorption time

Abstract

The invention discloses an electrostatic chuck device and method for shortening desorption time, and belongs to the technical field of electrostatic chucks. The electrostatic chuck device comprises an electrostatic chuck body, at least one main adsorption electrode arranged in the electrostatic chuck body and a main power source connected with the main adsorption electrode; the system further comprises a multi-mode active desorption promotion module. The method for shortening the desorption time comprises the following steps: S1, receiving a desorption instruction; s2, closing the main adsorption voltage; s3, starting a multi-mode active desorption promotion module; and S4, the workpiece is lifted. And S5, stopping the multi-mode active desorption promotion module.

Description

Technical Field

[0001] This invention relates to the field of electrostatic chuck technology, and in particular to an electrostatic chuck device and method for shortening desorption time. Background Technology

[0002] In existing technologies, electrostatic chucks primarily utilize electrostatic adsorption to attract and fix wafers, solving problems such as insufficient processing precision, susceptibility to warping, and inability to operate in vacuum environments inherent in traditional mechanical or vacuum chucks. They are widely used in semiconductor manufacturing processes. However, in actual production, after the adsorption voltage is turned off, residual charge remains between the dielectric layer and the wafer, generating residual electrostatic force. This prevents the wafer from immediately detaching from the electrostatic chuck for the next process, reducing production efficiency. Traditional methods to address this problem include applying a reverse voltage to generate a charge with opposite polarity between the dielectric layer and the wafer, neutralizing the residual charge and resolving the difficulty of de-attaching the electrostatic chuck during production.

[0003] The main shortcoming of the existing technology is that when there are inherent defects in the dielectric layer material that form deep traps (such as the introduction of specific defects or doping elements), the migration of charge carriers will be effectively suppressed. This high energy barrier means that once the charge is trapped, it is necessary to overcome a large amount of energy to escape. Therefore, applying a reverse voltage for desorption is not effective in this case. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an electrostatic chuck device and method for shortening the desorption time, so as to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] The present invention discloses an electrostatic chuck device for shortening desorption time. The electrostatic chuck device includes an electrostatic chuck body, at least one main adsorption electrode disposed inside the electrostatic chuck body, a main power supply connected to the main adsorption electrode, and a multimodal active desorption promotion module.

[0007] Preferably, the multimodal active desorption promotion module includes at least one piezoelectric element, which is embedded inside the electrostatic chuck body or attached to the bottom of the electrostatic chuck body, and is used to generate high-frequency mechanical vibration during the desorption stage.

[0008] Preferably, the piezoelectric element is a piezoelectric sheet, and there are more than one piezoelectric sheet embedded in the electrostatic chuck body in an array. The spacing between adjacent piezoelectric sheets is 20mm, the driving signal is a 50kHz sine wave, the peak voltage is 40V, and the duration is 200ms.

[0009] Preferably, the multimodal active desorption promotion module includes a switchable reverse polarity power supply unit electrically connected to the main adsorption electrode, used to output a reverse polarity voltage with dynamically adjustable amplitude, waveform and duration during the desorption stage.

[0010] Preferably, the switchable reverse polarity power supply unit is a programmable power supply, and its working method is as follows: initially apply a reverse square wave with a -50% adsorption voltage for a duration of 50μs, and then apply an oscillating wave with linearly decaying amplitude and a frequency of 1MHz for a duration of 500μs.

[0011] Preferably, the multimodal active desorption promotion module includes an enhanced micro-gap gas distribution and charge export channel with a depth of 50 μm and a width of 300 μm. It also includes conductive bumps made of boron-doped diamond with a diameter of 100 μm and a height of 20 μm, located on the center line at the bottom of the channel and spaced at 500 μm intervals. These bumps are connected to the annular export electrode surrounding the edge of the electrostatic chuck body through an internal metallized channel.

[0012] Another aspect of the present invention discloses a method for shortening the desorption time using the above-described electrostatic chuck device, the method comprising the following steps:

[0013] The method includes the following steps:

[0014] S1: Receive desorption command

[0015] The controller receives a command from the electrostatic chuck body that the workpiece needs to be released;

[0016] S2: Turn off the main adsorption voltage

[0017] Cut off the main adsorption voltage applied to the main adsorption electrode;

[0018] S3: Activate the multimodal active desorption promotion module

[0019] Activate any one of the following operations, or activate all three or any two of the following operations simultaneously, or activate the following three or any two operations sequentially:

[0020] Activate the piezoelectric element and apply an electrical signal of a specific frequency and amplitude to cause high-frequency micro-vibration on the surface of the electrostatic chuck body;

[0021] Activate the switchable reverse polarity power supply and apply a dynamically adjusted reverse polarity voltage waveform according to a preset strategy or real-time feedback;

[0022] Turn on the gas purging and activate the charge output channel. Blow gas into the electrostatic chuck body and the gap between the workpiece, and at the same time ground the annular output electrode or connect it to a low potential.

[0023] S4: Lift the workpiece

[0024] After confirming that the workpiece has been effectively detached, control the lifting pin to smoothly lift and move the workpiece away.

[0025] S5: Stop the multimodal active desorption promotion module

[0026] Stop activating the piezoelectric element, turn off the switchable reverse polarity power supply, turn off gas purging, and turn off the annular lead-out electrode.

[0027] Preferably, after the multimodal active desorption promotion module is activated, the separation status is monitored. A gap sensor, pressure sensor or current sensor is used to monitor whether the workpiece has started to separate or whether the residual force has dropped below the safety threshold. The workpiece is lifted only after the requirements are met.

[0028] The above technical solution has the following beneficial effects:

[0029] Desorption time is significantly shortened: by actively neutralizing charges and breaking physical adhesion, desorption can be completed faster than traditional methods, especially for workpieces that are difficult to desorb;

[0030] More thorough and reliable desorption: Multimodal synergy ensures that residual force is minimized, avoiding workpiece "sticking" or accidental ejection, and improving process stability and yield;

[0031] High versatility: The combination scheme can adapt to different types of workpieces and different process environments;

[0032] Integrability: Piezoelectric elements and conductive bumps can be integrated into existing suction cup structures, making upgrade and modification costs relatively controllable. Attached Figure Description

[0033] Figure 1 This is a flowchart of the method for shortening desorption time according to the present invention;

[0034] Figure 2 This is a cross-sectional view of the electrostatic chuck device of the present invention;

[0035] Figure 3 This is a schematic diagram of the enhanced micro-gap gas distribution and charge extraction channel of the present invention. Detailed Implementation

[0036] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0037] The purpose of this invention is to overcome the existing technical problems and provide a rapid desorption method for electrostatic chucks, which can actively, quickly and effectively neutralize residual charges and promote the physical separation of wafers from electrostatic chucks, thereby significantly shortening the desorption time, improving equipment production efficiency, and ensuring the stability and reliability of the desorption process, avoiding wafer damage or ejection.

[0038] Example 1

[0039] refer to Figure 2 An electrostatic chuck device for shortening desorption time includes an electrostatic chuck body 1, at least one main adsorption electrode 2 disposed inside the electrostatic chuck body 1, a main power supply connected to the main adsorption electrode 2, a lifting pin for lifting the workpiece, and a gas supply channel, and also includes a multimodal active desorption promotion module.

[0040] Specifically, the electrostatic chuck device includes an electrostatic chuck body 1 and a main adsorption electrode 2 disposed inside the electrostatic chuck body 1. The electrostatic chuck body 1 is used to adsorb and fix the wafer. After the main adsorption electrode 2 is powered on, it generates electrostatic adsorption force to adsorb and fix the wafer. The lifting pin separates the wafer after the multimodal active desorption promotion module is activated. The gas supply channel is used to supply cooling gas to the inside of the electrostatic chuck body 1. The electrostatic chuck also includes a multimodal active desorption promotion module, which is used when the electrostatic chuck device needs to desorb the wafer. This module is activated when the electrostatic chuck device needs to desorb the wafer to facilitate desorption. By setting this module, the desorption time can be shortened to improve work efficiency.

[0041] In some embodiments, the multimodal active desorption promotion module includes at least one piezoelectric element 3, which is embedded inside the electrostatic chuck body 1 or attached to the bottom of the electrostatic chuck body 1, for generating high-frequency mechanical vibration during the desorption stage. Specifically, the multimodal active desorption promotion module includes at least one piezoelectric element 3, such as one or two piezoelectric elements 3, which are specifically disposed inside the electrostatic chuck body 1 or attached to the bottom of the electrostatic chuck body 1. During the desorption stage, an electrical pulse signal of specific frequency and amplitude is applied to generate high-frequency micron or submicron level mechanical vibration. This vibration can effectively disturb the charge traps inside the dielectric layer, promote the release and migration of the bound charges. This high-frequency micron or submicron level mechanical vibration is transmitted to the surface of the electrostatic chuck device, generating a small and high-frequency shearing action at the interface between the electrostatic chuck device and the wafer, effectively destroying the adhesion formed by residual electrostatic force, creating an initial separation point for gas purging or lifting pin action, which can greatly reduce the overall separation force and facilitate wafer separation.

[0042] The piezoelectric element 3 is a piezoelectric sheet, and there are more than one piezoelectric sheet. They are embedded in the electrostatic chuck body 1 in an array. The spacing between adjacent piezoelectric sheets is 20mm. The driving signal is a 50kHz sine wave with a peak voltage of 40V and a duration of 200ms. Specifically, the piezoelectric element 3PZT-5H piezoelectric sheet has a length and width of 5mm and a thickness of 0.5mm. There are two or three of them. They are arranged in an array and embedded in the electrostatic chuck body 1. Specifically, they can be embedded in the area of ​​the main adsorption electrode 2. The piezoelectric sheets arranged in the array are spaced 20mm apart. The driving signal is a 50kHz sine wave with a peak voltage of 40V and a duration of 200ms.

[0043] In some embodiments, the multimodal active desorption promotion module includes a switchable reverse polarity power supply unit electrically connected to the main adsorption electrode 2, used to output a reverse polarity voltage with dynamically adjustable amplitude, waveform and duration during the desorption stage;

[0044] The switchable reverse polarity power supply unit can be a programmable power supply, and its working method is as follows: initially apply a reverse square wave with a -50% adsorption voltage for a duration of 50μs, and then apply an oscillating wave with linearly decaying amplitude and a frequency of 1MHz for a duration of 500μs.

[0045] The reverse voltage is not fixed and unchanging. Instead, it needs to be monitored in real time by a highly sensitive sensor to dynamically adjust the amplitude, waveform and time of the reverse voltage. For example, a reverse voltage is first applied to quickly neutralize most of the mobile charges, and then a low-amplitude voltage with a specific waveform (such as a damped oscillating wave) is applied to neutralize the deep-trapped charges.

[0046] In some embodiments, the multimodal active desorption promotion module includes an enhanced micro-gap gas distribution and charge export channel 4 with a depth of 50 μm and a width of 300 μm, and also includes conductive bumps 5 made of boron-doped diamond with a diameter of 100 μm and a height of 20 μm, located on the center line at the bottom of the channel with a spacing of 500 μm, and connected to the annular export electrode surrounding the edge of the electrostatic chuck body 1 through an internal metallized channel;

[0047] Specifically, the multimodal active desorption promotion module may also include an enhanced micro-gap gas distribution and charge removal channel 4, as referenced. Figure 3The enhanced micro-gap gas distribution and charge extraction channel 4 is specifically set on the adsorption working surface of the electrostatic chuck body 1, including several concentric circular groove structures. The center of each concentric circular groove is located at the center of the electrostatic chuck body 1. Each concentric circular groove has a depth of 50 μm and a width of 300 μm. It also includes conductive bumps 5. The conductive bumps 5 are made of boron-doped diamond. The conductive bumps 5 are cylindrical protrusions with a diameter of 100 μm and a height of 20 μm, located on the bottom center line of each concentric circular groove. The interval between adjacent conductive bumps 5 is 500 μm. Each conductive bump 5 is connected to the annular extraction electrode surrounding the edge of the electrostatic chuck body 1 through an internal metallized channel. The concentric circular groove structure design of the adsorption working surface of the electrostatic chuck body 1 is optimized so that its distribution is more conducive to forming an effective airflow in the small lifting gap. Small conductive bumps 5 are set in the concentric circular groove structure. These conductive bumps 5 are connected to a dedicated annular extraction electrode in the electrostatic chuck body. The annular extraction electrode is connected to ground or a controllable potential through a switch to facilitate operation during desorption.

[0048] Example 2

[0049] refer to Figure 1 A method for shortening wafer desorption time using the above-mentioned electrostatic chuck device specifically includes the following steps:

[0050] Step S1: Receive desorption command

[0051] The controller receives an instruction from the electrostatic chuck body 1 that the workpiece needs to be released;

[0052] Step S2: Turn off the main adsorption voltage

[0053] Cut off the main adsorption voltage applied to the main adsorption electrode 2. The main adsorption voltage can be DC or AC.

[0054] Step S3: Activate the multimodal active desorption promotion module

[0055] Activate any one of the following operations, or activate all three or any two of the following operations simultaneously, or activate the following three or any two operations sequentially:

[0056] 1. Activate the piezoelectric element 3 and apply an electrical signal of a specific frequency and amplitude to cause high-frequency micro-vibration on the surface of the electrostatic chuck body 1;

[0057] 2. Activate switchable reverse polarity power supply: Apply a dynamically adjusted reverse polarity voltage waveform according to a preset strategy or real-time feedback;

[0058] 3. Start gas purging and activate charge output channel: Blow gas into the gap between the electrostatic chuck body 1 and the workpiece, and at the same time ground the annular output electrode or connect it to a low potential;

[0059] Specifically, the multimodal active desorption promotion module on the electrostatic chuck device includes any one of the following three components: piezoelectric element 3, switchable reverse polarity power supply unit, and enhanced micro-gap gas distribution and charge removal channel 4. To activate the multimodal active desorption promotion module, one must perform any one of the following three operations:

[0060] 1. Activate the piezoelectric element 3 and apply an electrical signal of a specific frequency and amplitude to cause high-frequency micro-vibration on the surface of the electrostatic chuck body 1;

[0061] 2. Activate switchable reverse polarity power supply: Apply a dynamically adjusted reverse polarity voltage waveform according to a preset strategy or real-time feedback;

[0062] 3. Start gas purging and activate charge output channel: Blow gas into the gap between the electrostatic chuck body 1 and the workpiece, and at the same time ground the annular output electrode or connect it to a low potential;

[0063] By performing any of the above operations, the wafer desorption time can be shortened; that is, any operation can shorten the desorption time.

[0064] Furthermore, the multimodal active desorption promotion module on the electric chuck device includes a piezoelectric element 3 or a switchable reverse polarity power supply unit. In this case, to activate the multimodal active desorption promotion module, the following operation is performed:

[0065] Activate the piezoelectric element 3 and apply an electrical signal of a specific frequency and amplitude to cause high-frequency micro-vibration on the surface of the electrostatic chuck body 1;

[0066] Activate the switchable reverse polarity power supply: Apply a dynamically adjusted reverse polarity voltage waveform according to a preset strategy or real-time feedback; after operation, the wafer desorption time can be shortened.

[0067] If the multimodal active desorption promotion module on the electrostatic chuck device includes a piezoelectric element 3 and an enhanced micro-gap gas distribution and charge removal channel 4, then to activate the multimodal active desorption promotion module, the following operation must be performed:

[0068] Activate the piezoelectric element 3 and apply an electrical signal of a specific frequency and amplitude to cause high-frequency micro-vibration on the surface of the electrostatic chuck body 1;

[0069] Start gas purging and activate charge export channel: blow gas into the gap between the electrostatic chuck body 1 and the workpiece, and at the same time ground the annular export electrode or connect it to a low potential. After the operation, the wafer desorption time can be shortened.

[0070] If the multimodal active desorption promotion module on the electrostatic chuck device includes a switchable reverse polarity power supply unit and an enhanced micro-gap gas distribution and charge removal channel 4, then to activate the multimodal active desorption promotion module, the following operations must be performed:

[0071] Activate switchable reverse polarity power supply: Apply dynamically adjusted reverse polarity voltage waveform according to preset strategy or real-time feedback;

[0072] To activate the charge export channel, blow gas into the electrostatic chuck body 1 and the gap between the workpiece, and at the same time ground the annular export electrode or connect it to a low potential. After the operation, the wafer desorption time can be shortened. The activation order can be to first activate the switchable reverse polarity power supply, and then activate the gas purging and charge export channel.

[0073] Furthermore, if the multimodal active desorption promotion module on the electrostatic chuck device includes a piezoelectric element 3, a switchable reverse polarity power supply unit, and an enhanced micro-gap gas distribution and charge removal channel 4, then to activate the multimodal active desorption promotion module, the following operations can be performed in sequence:

[0074] 1. Activate the piezoelectric element 3 and apply an electrical signal of a specific frequency and amplitude to cause high-frequency micro-vibration on the surface of the electrostatic chuck body 1;

[0075] 2. Activate switchable reverse polarity power supply: Apply a dynamically adjusted reverse polarity voltage waveform according to a preset strategy or real-time feedback;

[0076] 3. Start gas purging and activate charge export channel: Blow gas into the gap between the electrostatic chuck body 1 and the workpiece, and at the same time ground the annular export electrode or connect it to a low potential; after the operation, the wafer desorption time can be shortened; this mode is the preferred mode, and the multi-modal synergistic effect of performing the above operations in sequence can ensure that the residual force is reduced to the minimum.

[0077] Step S4: Lift the workpiece

[0078] After confirming that the workpiece has been effectively detached, control the lifting pin to smoothly lift and remove the workpiece, that is, remove the wafer. Specifically, the effective detachment can be determined by the time of the above operation. The specific time can be tested according to the various methods mentioned above, and a safety time should be reserved.

[0079] Step S5: Stop the multimodal active desorption promotion module

[0080] After the workpiece is separated and removed, the activation of piezoelectric element 3 can be stopped, the activation switchable reverse polarity power supply can be turned off, the gas purging can be turned off, the annular discharge electrode can be turned off, and the processing and adsorption of the next workpiece can begin.

[0081] In some embodiments, after the multimodal active desorption promotion module is activated, the separation status is monitored. A gap sensor, pressure sensor or current sensor is used to monitor whether the workpiece has started to separate or whether the residual force has dropped below a safe threshold. If the requirements are met, the workpiece is lifted to ensure separation.

[0082] Compared with the prior art, the technical solution of this application has the following advantages:

[0083] Desorption time is significantly shortened: by actively neutralizing charges (reverse polarity + charge removal) and / or breaking physical adhesion (piezoelectric vibration), desorption can be completed several times or even an order of magnitude faster than traditional methods, especially for workpieces that are difficult to desorb (such as thick oxide silicon wafers and glass substrates).

[0084] More thorough and reliable desorption: Multimodal synergy ensures that residual force is minimized, avoiding workpiece "stickiness" or accidental ejection, and improving process stability and yield.

[0085] High versatility: The combination scheme can adapt to different types of workpieces (conductors, semiconductors, insulators) and different process environments (atmosphere, vacuum).

[0086] Integrability: The piezoelectric element 3 and conductive bump 5 can be integrated into the existing suction cup structure, and the upgrade and transformation cost is relatively controllable.

[0087] Intelligent: By combining sensor feedback, adaptive control can be achieved to optimize desorption parameters.

[0088] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. An electrostatic chuck device for shortening desorption time, characterized in that, The electrostatic chuck device includes an electrostatic chuck body, at least one main adsorption electrode disposed inside the electrostatic chuck body, a main power supply connected to the main adsorption electrode, and a multimodal active desorption promotion module.

2. The electrostatic chuck device for shortening desorption time according to claim 1, characterized in that, The multimodal active desorption promotion module includes at least one piezoelectric element, which is embedded inside the electrostatic chuck body or attached to the bottom of the electrostatic chuck body, and is used to generate high-frequency mechanical vibration during the desorption stage.

3. The electrostatic chuck device for shortening desorption time according to claim 2, characterized in that, The piezoelectric element is a piezoelectric sheet, and there are more than one piezoelectric sheet embedded in the electrostatic chuck body in an array. The spacing between adjacent piezoelectric sheets is 20mm. The driving signal is a 50kHz sine wave with a peak voltage of 40V and a duration of 200ms.

4. The electrostatic chuck device for shortening desorption time according to claim 1, characterized in that, The multimodal active desorption promotion module includes a switchable reverse polarity power supply unit, which is electrically connected to the main adsorption electrode and is used to output a reverse polarity voltage with dynamically adjustable amplitude, waveform and duration during the desorption stage.

5. The electrostatic chuck device for shortening desorption time according to claim 4, characterized in that, The switchable reverse polarity power supply unit is a programmable power supply. Its working method is as follows: initially, a reverse square wave with a -50% adsorption voltage is applied for a duration of 50μs, followed by an oscillation wave with linearly decaying amplitude and a frequency of 1MHz for a duration of 500μs.

6. The electrostatic chuck device for shortening desorption time according to claim 1, characterized in that, The multimodal active desorption promotion module includes an enhanced micro-gap gas distribution and charge export channel with a depth of 50 μm and a width of 300 μm. It also includes conductive bumps made of boron-doped diamond with a diameter of 100 μm and a height of 20 μm. These bumps are located on the center line at the bottom of the channel and spaced 500 μm apart. They are connected to the annular export electrode surrounding the edge of the electrostatic chuck body through an internal metallized channel.

7. A method for shortening desorption time using the electrostatic chuck device as described in any one of claims 1-6, characterized in that, The method includes the following steps: S1: Receive desorption command The controller receives a command from the electrostatic chuck body that the workpiece needs to be released; S2: Turn off the main adsorption voltage Cut off the main adsorption voltage applied to the main adsorption electrode; S3: Activate the multimodal active desorption promotion module Activate any one of the following operations, or activate all three or any two of the following operations simultaneously, or activate the following three or any two operations sequentially: Activate the piezoelectric element and apply an electrical signal of a specific frequency and amplitude to cause high-frequency micro-vibration on the surface of the electrostatic chuck body; Activate the switchable reverse polarity power supply and apply a dynamically adjusted reverse polarity voltage waveform according to a preset strategy or real-time feedback; Turn on the gas purging and activate the charge output channel. Blow gas into the electrostatic chuck body and the gap between the workpiece, and at the same time ground the annular output electrode or connect it to a low potential. S4: Lift the workpiece After confirming that the workpiece has been effectively detached, control the lifting pin to smoothly lift and move the workpiece away. S5: Stop the multimodal active desorption promotion module Stop activating the piezoelectric element, turn off the switchable reverse polarity power supply, turn off gas purging, and turn off the annular lead-out electrode.

8. The method for shortening desorption time according to claim 7, characterized in that, After the multimodal active desorption promotion module is activated, the separation status is monitored. The gap sensor, pressure sensor or current sensor is used to monitor whether the workpiece has started to separate or whether the residual force has dropped below the safety threshold. The workpiece is lifted only after the requirements are met.

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