Electrostatic neutralization method and apparatus based on pecvd

Abstract

This application discloses a static electricity neutralization method and apparatus based on PECVD, belonging to the field of semiconductor thin film deposition technology. It includes: applying a first radio frequency (RF) to a reaction chamber to ionize a continuously introduced reactive gas into the chamber, forming plasma which is then deposited onto the wafer surface; after stopping the introduction of the reactive gas and the application of the first RF, applying a second RF in the chamber, wherein the power of the second RF is lower than that of the first RF, and the voltage polarity of the second RF is opposite to that of the first RF; moving a heater base on which the wafer is placed downwards to increase the gap between the wafer and the heater base, thereby facilitating the neutralization of static electricity between the wafer and the heater base by the second RF; and after stopping the application of the second RF, introducing a purge gas into the chamber to clean the wafer surface. This application neutralizes static electricity through low-power plasma discharge, avoiding the problems of wafer breakage and adhesion caused by electrostatic forces between the wafer and the heater base.

Description

Technical Field

[0001] This application relates to the field of semiconductor thin film deposition technology, and in particular to a static electricity neutralization method and apparatus based on PECVD. Background Technology

[0002] In semiconductor manufacturing, plasma-enhanced chemical vapor deposition (PECVD) is widely used to deposit various dielectric thin films on wafer surfaces. In this process, the wafer is placed on a heater substrate covered with a dielectric material such as ceramic or anodic aluminum oxide. Under radio frequency (RF) excitation, the reactive gas ionizes to form plasma, completing the deposition. However, after the deposition step is completed and the RF power is turned off, a significant electrostatic field forms between the wafer and the grounded heater substrate due to the non-uniform distribution and capture of charged particles in the plasma on the wafer surface and dielectric layer. This generates a strong electrostatic force, primarily an electrostatic adsorption force.

[0003] The presence of this electrostatic force leads to two serious consequences: First, when the reaction chamber is evacuated, the heater base descends to the predetermined position, and the lift pin performs its lifting action, the wafer cannot be successfully lifted due to the electrostatic force firmly adhering to the base surface, resulting in a "lifting failure." Second, even if the wafer is managed to be lifted, during the unloading process by the robot arm entering the reaction chamber, the wafer may suddenly release or shift its position due to the electrostatic force, causing it to collide with the robot arm or the chamber and break. This directly results in product breakage and yield loss, and increases the frequency and cost of PECVD equipment maintenance.

[0004] Currently, conventional solutions for electrostatic forces in the industry mainly rely on optimizing the gas purging step at the end of the process, attempting to flush away some of the charge by extending the purging time or increasing the purging gas flow rate. However, this method is inefficient, time-consuming, and gas-intensive, and has limited effectiveness in neutralizing existing strong electrostatic forces. Another approach is to improve the physical properties of the heater substrate surface, such as using special roughening treatments to reduce the contact area between the substrate surface and the wafer. However, this is a passive preventative measure that cannot eliminate the generation of electrostatic forces and may introduce thermal uniformity problems. Existing technologies lack an effective integrated method for actively, rapidly, and accurately neutralizing the electrostatic forces between the wafer and the substrate at the end of the PECVD process sequence.

[0005] Therefore, a technical solution is needed that does not affect the core process parameters of PECVD, can efficiently neutralize the electrostatic force between the wafer and the heater substrate, and is stable and reliable in the long term, in order to solve the problem of wafer breakage and adhesion caused by electrostatics. Summary of the Invention

[0006] To address the problem of wafer adhesion and cracking caused by electrostatic forces between the wafer and the heater substrate in the existing PECVD process, this application mainly provides a method and apparatus for electrostatic neutralization based on PECVD.

[0007] To achieve the above objectives, the first technical solution adopted in this application is: providing a PECVD-based electrostatic neutralization method, comprising: applying a first radio frequency (RF) to a reaction chamber to ionize a continuously introduced reaction gas in the reaction chamber to form plasma, which is then deposited on the wafer surface; stopping the introduction of the reaction gas in the reaction chamber and stopping the application of the first RF in the reaction chamber, and then applying a second RF in the reaction chamber, wherein the power of the second RF is lower than that of the first RF, and the voltage polarity of the second RF is opposite to that of the first RF; moving a heater base in the reaction chamber on which the wafer is placed downward to increase the gap between the wafer and the heater base, so as to facilitate the neutralization of electrostatic charge between the wafer and the heater base by the second RF; and after stopping the application of the second RF in the reaction chamber, introducing a purge gas into the reaction chamber to clean the wafer surface.

[0008] Preferably, the power of the second radio frequency is in the range of eight percent to twelve percent of the power of the first radio frequency.

[0009] Preferably, during the application of the second radio frequency in the reaction chamber, the duration of the second radio frequency is 3 to 8 seconds.

[0010] Preferably, after stopping the flow of the reaction gas into the reaction chamber and stopping the application of the first radio frequency in the reaction chamber, the second radio frequency is applied in the reaction chamber, including: the second radio frequency ionizes the reaction gas in the reaction chamber to form a low-density plasma, and the positive and negative charges in the low-density plasma move to the negative and positive static charge regions formed by electrostatic discharge between the wafer and the heater base, respectively, to neutralize the static charge.

[0011] Preferably, during the process of applying the second radio frequency in the reaction chamber and during the process of applying the first radio frequency in the reaction chamber, the vacuum level in the reaction chamber is adjusted to a preset vacuum level, the preset vacuum level being in the range of 4 to 8 Tols.

[0012] Preferably, the process of applying the second radio frequency in the reaction chamber is synchronized with the process of moving the heater base in the reaction chamber, in which the wafer is placed, downward.

[0013] Preferably, moving the heater base in the reaction chamber where the wafer is placed downwards includes: driving the heater base downwards by 50 to 70 mm via a lifting mechanism.

[0014] Preferably, the process of introducing purge gas into the reaction chamber lasts for 15 seconds or more.

[0015] Preferably, the power of the first radio frequency ranges from 300 to 1500 watts, and the frequency is 13.56 MHz.

[0016] The second technical solution adopted in this application is: providing a static electricity neutralization device based on PECVD, comprising: a first radio frequency (RF) application module, which applies a first RF to a reaction chamber to ionize the continuously introduced reaction gas in the reaction chamber to form plasma, which is then deposited on the wafer surface; a second RF application module, which applies a second RF to the reaction chamber after stopping the introduction of the reaction gas and stopping the application of the first RF, wherein the power of the second RF is lower than that of the first RF, and the voltage polarity of the second RF is opposite to that of the first RF; a lifting mechanism, which moves downward a heater base in the reaction chamber on which the wafer is placed, thereby increasing the gap between the wafer and the heater base to facilitate the neutralization of static electricity between the wafer and the heater base by the second RF; and a purging module, which introduces purging gas into the reaction chamber after stopping the application of the second RF to clean the wafer surface.

[0017] The beneficial effects of the technical solution of this application are as follows: This application designs an electrostatic neutralization method based on PECVD. In the PECVD process flow, after the deposition step is completed and before the gas purging step begins, a low-power plasma discharge neutralization step is inserted. By applying radio frequency energy lower than that in the deposition step, a low-density weak plasma is excited under controlled conditions. The plasma actively neutralizes the charge accumulated between the wafer and the heater base using its conductivity, thereby eliminating electrostatic force and creating ideal conditions for wafer lifting and unloading in subsequent process flows. By increasing the gap between the wafer and the heater base, the binding force of the electrostatic field is weakened. The dual approach of reverse voltage plasma neutralization and physical destruction of the electrostatic field, compared with a single electrostatic neutralization method, avoids charge re-accumulation, makes electrostatic suppression more thorough, and effectively solves the problem of wafer adhesion and cracking caused by electrostatic force. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating a specific implementation of a PECVD-based electrostatic neutralization method according to this application. Figure 2This is a schematic diagram of the wafer thin film deposition process based on a specific embodiment of this application; Figure 3 This is a schematic diagram of a specific embodiment of a PECVD-based electrostatic neutralization device according to this application.

[0020] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0021] The preferred embodiments of this application will now be described in detail with reference to the accompanying drawings, so that the advantages and features of this application can be more easily understood by those skilled in the art, thereby providing a clearer and more definite definition of the scope of protection of this application.

[0022] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0023] In existing PECVD equipment, after the deposition process, strong electrostatic forces arise between the wafer and the heater base due to charge accumulation. This can lead to subsequent ejector pin lifting failures or wafer displacement and breakage during unloading. Current technologies primarily mitigate this by passively extending the purging process or modifying hardware, failing to actively and efficiently neutralize the electrostatic forces at the back end of the PECVD process. This invention aims to solve the reliability problem of wafer lifting and unloading caused by electrostatic attraction after the deposition step, preventing wafer breakage and production interruptions.

[0024] The inventive concept of this application is as follows: At the end of the standard PECVD process cycle, after the deposition step and before the gas purging step, a low-power plasma discharge neutralization step is inserted. This step applies a radio frequency energy far lower than the deposition power to excite a low-density weak plasma under controlled conditions. The plasma's conductivity is used to actively neutralize the charge accumulated at the interface between the wafer and the heater base, thereby eliminating electrostatic forces and creating ideal conditions for subsequent wafer lifting and unloading. At the same time, by increasing the electrode gap, the gap between the wafer and the heater base is increased compared to the deposition stage, physically disrupting the stable structure of the electrostatic field, weakening the binding force of the electrostatic field, and assisting in charge dissipation.

[0025] This application achieves electrostatic suppression through a dual mechanism of reverse voltage electrostatic neutralization and physical disruption of the electrostatic field. The working principle is as follows: After the deposition step, dissimilar electrostatic charges accumulate between the wafer and the heater substrate due to plasma reaction, forming a stable electrostatic field and strong electrostatic force. The RF power supply uses a low-power RF control module to output a low-power RF signal with a reverse voltage, which excites the residual gas in the chamber to form a low-density plasma. The positive and negative charges in the plasma move towards the dissimilar charge regions between the wafer and the substrate, respectively, to neutralize the electrostatic charges and reduce the electrostatic voltage. The synchronously executed wide-gap movement operation increases the gap between the wafer and the upper electrode, reduces the electric field strength in the chamber, and weakens the binding force of the electrostatic field. The subsequent gas purging step removes byproducts and residual active particles in the chamber, ensuring the wafer surface is clean, and ultimately achieving electrostatic-free and damage-free unloading of the wafer.

[0026] The technical solutions of this application and how they solve the aforementioned technical problems will be described in detail below with specific embodiments. The specific embodiments described below can be combined with each other to form new embodiments. The same or similar ideas or processes described in one embodiment may not be repeated in other embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0027] Figure 1 This paper illustrates a specific embodiment of a PECVD-based electrostatic neutralization method according to this application.

[0028] exist Figure 1In the specific embodiment shown, the electrostatic neutralization method based on PECVD includes: step S101, applying a first radio frequency (RF) to the reaction chamber to ionize the continuously introduced reaction gas in the reaction chamber to form plasma, which is then deposited on the wafer surface; step S102, after stopping the introduction of the reaction gas and stopping the application of the first RF in the reaction chamber, applying a second RF in the reaction chamber, wherein the power of the second RF is lower than that of the first RF, and the voltage polarity of the second RF is opposite to that of the first RF; step S103, moving the heater base in the reaction chamber where the wafer is placed downward to increase the gap between the wafer and the heater base, so as to facilitate the neutralization of electrostatic charge between the wafer and the heater base by the second RF; step S104, after stopping the application of the second RF in the reaction chamber, introducing a purge gas into the reaction chamber to clean the wafer surface.

[0029] exist Figure 1 In the specific embodiment shown, after the deposition step is completed and before the gas purging step in the PECVD process, a low-power plasma discharge neutralization step is inserted. This method uses a dual approach of reverse voltage plasma neutralization and physical disruption of the electrostatic field. By utilizing its conductivity, the method actively neutralizes the charge accumulated between the wafer and the heater substrate, thereby eliminating electrostatic force. Compared with a single electrostatic neutralization method, this method avoids charge re-accumulation, makes electrostatic suppression more thorough, and effectively solves the problem of wafer adhesion and cracking caused by electrostatic force.

[0030] In this specific embodiment, in step S101, a first radio frequency is applied to the reaction chamber to ionize the continuously introduced reaction gas in the reaction chamber, forming plasma which is then deposited on the wafer surface. After deposition, dissimilar electrostatic charges accumulate between the wafer and the heater base due to the plasma reaction excited by the first radio frequency, forming a stable electrostatic field and strong electrostatic force. When the reaction chamber completes the evacuation, the heater base descends, and the ejector pin performs the lifting action, the wafer cannot be successfully lifted because it is firmly attracted to the base surface by the electrostatic force, resulting in "lifting failure". Even if the wafer is barely lifted, during the process of the robotic arm entering the chamber for unloading, the wafer may suddenly release the electrostatic force or shift its position, causing it to collide with the robotic arm or the chamber and break.

[0031] In this specific embodiment, in step S102, after stopping the flow of reaction gas into the reaction chamber and ceasing the application of the first radio frequency (RF) signal, a second RF signal is applied to the reaction chamber. The power of the second RF signal is lower than that of the first RF signal, and the voltage polarity of the second RF signal is opposite to that of the first RF signal. The original RF power supply of the PECVD equipment is started, and a low-power RF signal with a reverse voltage (i.e., the second RF signal) is output using the low-power RF control module. This excites the residual reaction gas in the chamber to form a low-density weak plasma. The positive and negative charges in the plasma move towards the opposite charge regions of the wafer and the substrate, respectively, achieving electrostatic charge neutralization and reducing the electrostatic voltage. The power of the second RF signal should be much lower than that of the first RF signal during the deposition process to avoid high-power discharge RF damage to the thin film already deposited on the wafer surface.

[0032] In this specific embodiment, in step S103, the heater base containing the wafer in the reaction chamber is moved downwards to increase the gap between the wafer and the heater base, thereby facilitating the second radio frequency neutralization of static electricity between the wafer and the heater base. This operation physically disrupts the stable structure of the electrostatic field by increasing the gap between the wafer and the upper electrode, reducing the electrostatic field strength between the wafer and the heater base, and further weakening the binding force of the electrostatic field.

[0033] In this specific embodiment, in step S104, after the application of the second radio frequency in the reaction chamber is stopped, purge gas is introduced into the reaction chamber to clean the wafer surface. The subsequent gas purging step can effectively remove byproducts generated by the deposition reaction in the chamber and active particles remaining from plasma discharge, preventing particles from adhering to the wafer surface, ensuring a clean wafer surface, and facilitating electrostatic-free and damage-free unloading of the wafer.

[0034] In one specific embodiment of this application, the power of the second radio frequency (RF) ranges from 8% to 12% of the power of the first RF. The power of the second RF should be much lower than the power of the first RF during the deposition process. Having the second RF power at 8% to 12% of the first RF power helps avoid damage to the thin film already deposited on the wafer surface from high-power RF.

[0035] In one specific embodiment of this application, the power of the second radio frequency is 10 percent of the power of the first radio frequency.

[0036] In one specific embodiment of this application, the duration of the second radio frequency (RF) during the application of the second RF in the reaction chamber is 3 to 8 seconds. Using the second RF for electrostatic neutralization for a total time of 3 to 8 seconds effectively neutralizes the electrostatic charge and reduces the electrostatic voltage. The duration of electrostatic neutralization can be adjusted according to the deposition formulation. Applying the second RF for too long will damage the thin film already deposited on the wafer surface.

[0037] In one specific embodiment of this application, the duration of the second radio frequency during the application of the second radio frequency in the reaction chamber is 8 seconds. The total time of 8 seconds for electrostatic neutralization using the second radio frequency effectively neutralizes the electrostatic charge, reduces the electrostatic voltage, and does not damage the thin film already deposited on the wafer surface.

[0038] In one specific embodiment of this application, after stopping the flow of reactant gas into the reaction chamber and ceasing the application of the first radio frequency (RF) in the reaction chamber, a second RF is applied to the reaction chamber. This includes: the second RF ionizing the reactant gas in the reaction chamber to form a low-density plasma; the positive and negative charges in the low-density plasma then move towards the negative and positive electrostatic charge regions formed by electrostatic discharge between the wafer and the heater base, respectively, neutralizing the electrostatic charge. This step is an active neutralization of electrostatic discharge, which can fundamentally eliminate electrostatic adsorption forces, rather than the indirect mitigation of existing technologies.

[0039] In one specific embodiment of this application, during the process of applying the second radio frequency in the reaction chamber and during the process of applying the first radio frequency in the reaction chamber, the vacuum level in the reaction chamber is adjusted to a preset vacuum level, which ranges from 4 to 8 Torr. Maintaining a stable vacuum level in the reaction chamber helps the low-power reverse radio frequency discharge step to better exert its electrostatic neutralization effect, while avoiding wafer particle contamination problems caused by drastic changes in chamber pressure.

[0040] In one specific embodiment of this application, during the process of applying the second radio frequency in the reaction chamber and during the process of applying the first radio frequency in the reaction chamber, the vacuum level in the reaction chamber is adjusted to a preset vacuum level, which is 6 Torr.

[0041] In one specific embodiment of this application, the process of applying the second radio frequency in the reaction chamber is synchronized with the process of moving the heater base in the reaction chamber, in which the wafer is placed, downward. The simultaneous application of low-power reverse radio frequency and the wide-gap movement operation physically disrupt the stable structure of the electrostatic field, reducing its strength and further weakening its binding force. This allows the low-power reverse second radio frequency to better neutralize electrostatic charges and more effectively eliminate the electrostatic force between the wafer and the heater base.

[0042] In one specific embodiment of this application, moving the heater base in the reaction chamber where the wafer is placed downwards includes: driving the heater base downwards by 50 to 70 millimeters via a lifting mechanism. Driving the heater base downwards by 50 to 70 millimeters via the lifting mechanism increases the gap between the wafer and the heater base compared to the deposition stage, physically disrupting the stable structure of the electrostatic field and aiding in charge dissipation.

[0043] In one specific embodiment of this application, the heater base is driven to move downward by 60 mm by a lifting mechanism to disrupt the stable structure of the electrostatic field, which is beneficial to the dissipation of static charge.

[0044] In one specific embodiment of this application, the process of introducing purge gas into the reaction chamber lasts for 15 seconds or more. Continuous purging for 15 seconds can effectively remove byproducts generated by the deposition reaction and active particles remaining from plasma discharge within the chamber, preventing particles from adhering to the wafer surface and ensuring a clean wafer surface, thereby achieving electrostatic-free and damage-free unloading of the wafer.

[0045] In one specific embodiment of this application, the power of the first radio frequency (RF) ranges from 300 to 1500 watts, and the frequency is 13.56 MHz. The power of the first RF can be adjusted according to the thin film material and thickness, thereby more precisely controlling the performance of the plasma-deposited thin film.

[0046] In one specific embodiment of this application, the power of the first radio frequency is 960 watts and the frequency is 13.56 MHz.

[0047] Figure 2 The process flow for wafer thin film deposition based on a specific embodiment of this application is shown.

[0048] exist Figure 2 In the specific embodiment shown, the wafer thin film deposition process based on this application includes a wafer loading step S201, a vacuuming step S202, a wafer preheating step S203, a deposition step S204, an electrostatic neutralization step S205, a gas purging step S206, a vacuuming step S207, and a wafer unloading step S208. The deposition step and the gas purging step are performed only once. This process adds an electrostatic neutralization step after the deposition step in existing PECVD processes. This step includes low-power RF discharge and wide-gap movement to achieve active electrostatic neutralization, fundamentally eliminating electrostatic forces rather than the indirect mitigation of existing technologies, thus creating ideal conditions for subsequent wafer lifting and unloading.

[0049] Figure 2 The specific embodiments shown are adaptable to the production of mainstream 12-inch wafers.

[0050] In this specific embodiment, the wafer loading step S201 includes: transferring the wafer to the center positioning position of the heater base by a robot arm, introducing argon (Ar) gas into the PECVD reaction chamber as a replacement gas, and expelling the air and residual process gas in the reaction chamber to ensure the initial cleanliness of the chamber environment; the chamber is kept at normal pressure during the replacement process.

[0051] In this specific embodiment, the vacuuming step S202 includes: starting the vacuum pump group, pumping the pressure in the PECVD reaction chamber to 8-12 millitors (mTorr), and maintaining this vacuum level for 60 seconds to eliminate airflow disturbances in the chamber and establish a stable vacuum environment for subsequent preheating and deposition processes.

[0052] In this specific embodiment, the wafer preheating step S203 includes: activating the temperature control system of the heater base to raise the base temperature to 400 degrees Celsius, the base temperature of which can be adjusted according to the thin film material; simultaneously introducing a preset process mixed gas into the reaction chamber, for example, when depositing silicon dioxide (SiO2) thin film, the process mixed gas is tetraethoxysilane (TEOS), oxygen (O2) and argon (Ar), and maintaining the chamber pressure at 6 Torr for 15 seconds through coordinated control of the gas flow valve and vacuum pump group, so as to homogenize the wafer temperature and prepare for the deposition reaction.

[0053] In this specific embodiment, deposition step S204 includes: activating the existing RF power supply of the PECVD equipment, outputting a first deposition RF with a power of 960W and a frequency of 13.56MHz, and a second deposition RF with a power of 210W and a frequency of 370kHz; adjusting the deposition time according to the film thickness; activating the reactive gas through plasma to complete film deposition on the wafer surface; maintaining the chamber pressure and process gas flow rate consistent with the preheating stage during the deposition process. The high-frequency deposition RF is used to generate and maintain the plasma, while the low-frequency deposition RF is used to independently control the energy of ion bombardment, thereby precisely controlling the film performance.

[0054] In this specific embodiment, after deposition step S204 is completed, the chamber vacuum level is maintained at 6 Torr, the process gas supply is stopped, and electrostatic neutralization step S205 is initiated. Electrostatic neutralization step S205 is a core innovative step, consisting of two synchronously executed operations: low-power reverse RF application and wide-gap movement. The low-power reverse RF application operation includes: switching the RF power supply to a low-power RF control module, outputting a second RF with a power of 96W. The polarity of the second RF voltage is opposite to that of the first deposition RF in the deposition step. The second RF ionizes the residual reactive gas in the chamber to form a low-density plasma. The positive and negative charges in the low-density plasma neutralize the dissimilar electrostatic charges between the wafer and the heater base, respectively. The power of the second RF is 10% of that of the first deposition RF, which helps avoid damage to the thin film already deposited on the wafer surface from high-power RF. The wide-gap movement operation includes: driving the heater base downwards by 60 mm via a lifting mechanism, increasing the gap between the wafer and the heater base compared to the deposition stage. This increased electrode gap simultaneously physically disrupts the stable structure of the electrostatic field, aiding in the discharge and neutralization of electrostatic charges. The duration of the low-power reverse RF application operation is 8 seconds.

[0055] In this specific embodiment, the gas purging step S206 includes: after the discharge step S205 is completed, oxygen (O2) and argon (Ar) are introduced into the reaction chamber as purging gases and purged continuously for 15 seconds to remove byproducts generated by the deposition reaction and active particles remaining from the plasma discharge in the chamber, so as to prevent particles from adhering to the wafer surface.

[0056] In this specific embodiment, the vacuuming step S207 includes: keeping the gas purge line closed, starting the vacuum pump group, extracting the gas and purge mixture from the reaction chamber, restoring the reaction chamber pressure to 8-12 millitors (mTorr), and establishing a stable vacuum environment for wafer unloading.

[0057] In this specific embodiment, the wafer unloading step S208 includes: extending a robotic arm into the reaction chamber, transferring the wafer from the heater base out of the reaction chamber, and completing a single PECVD process.

[0058] exist Figure 2 In the specific embodiments shown, the wafer thin film deposition process based on this application simplifies the existing PECVD process of two deposition steps and two gas purging steps into a single deposition and a single purging. This solves the problem of electrostatic superposition caused by two depositions, optimizes the process architecture, and improves production efficiency. At the same time, by using a dual approach of reverse voltage plasma neutralization and physical destruction of the electrostatic field, compared with a single electrostatic neutralization method, charge re-accumulation is avoided, making electrostatic suppression more thorough and completely solving the problems of wafer breakage and adhesion.

[0059] Figure 3 This is a schematic diagram of a specific embodiment of a PECVD-based electrostatic neutralization device according to this application.

[0060] exist Figure 3 In the specific embodiment shown, the electrostatic neutralization device based on PECVD includes: a first radio frequency (RF) application module 301, which applies a first RF to the reaction chamber to ionize the continuously introduced reaction gas in the reaction chamber to form plasma, which is then deposited on the wafer surface; a second RF application module 302, which applies a second RF to the reaction chamber after the introduction of reaction gas and the application of the first RF are stopped, wherein the power of the second RF is lower than that of the first RF, and the voltage polarity of the second RF is opposite to that of the first RF; a lifting mechanism 303, which moves downward the heater base in the reaction chamber where the wafer is placed, thereby increasing the gap between the wafer and the heater base to facilitate the neutralization of electrostatic charge between the wafer and the heater base by the second RF; and a purging module 304, which introduces purging gas into the reaction chamber after the application of the second RF is stopped to clean the wafer surface.

[0061] The PECVD-based electrostatic neutralization device provided in this application can be used to perform the PECVD-based electrostatic neutralization method described in any of the above embodiments. Its implementation principle and technical effect are similar, and will not be repeated here.

[0062] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0063] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0064] The above description is merely an embodiment of this application and does not limit the patent scope of this application. Any equivalent structural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A PECVD-based electrostatic neutralization method, characterized in that, include: A first radio frequency is applied to the reaction chamber to ionize the reaction gas continuously introduced into the reaction chamber to form plasma, which is then deposited on the wafer surface. After the flow of the reaction gas into the reaction chamber is stopped and the application of the first radio frequency in the reaction chamber is stopped, a second radio frequency is applied in the reaction chamber, wherein the power of the second radio frequency is lower than that of the first radio frequency, and the voltage polarity of the second radio frequency is opposite to that of the first radio frequency. The heater base in the reaction chamber where the wafer is placed is moved downward to increase the gap between the wafer and the heater base, so as to facilitate the second radio frequency neutralization of the static electricity between the wafer and the heater base; After the second radio frequency is stopped in the reaction chamber, a purge gas is introduced into the reaction chamber to clean the wafer surface.

2. The electrostatic neutralization method based on PECVD according to claim 1, characterized in that, The power of the second radio frequency ranges from eight percent to twelve percent of the power of the first radio frequency.

3. The electrostatic neutralization method based on PECVD according to claim 1, characterized in that, During the application of the second radio frequency in the reaction chamber, the duration of the second radio frequency is 3 to 8 seconds.

4. The electrostatic neutralization method based on PECVD according to claim 1, characterized in that, After stopping the flow of the reaction gas into the reaction chamber and stopping the application of the first radio frequency in the reaction chamber, applying the second radio frequency in the reaction chamber includes: The second radio frequency ionizes the reaction gas in the reaction chamber to form a low-density plasma. The positive and negative charges in the low-density plasma move toward the negative and positive static charge regions formed by electrostatic discharge between the wafer and the heater base, respectively, to neutralize the static charge.

5. The electrostatic neutralization method based on PECVD according to claim 1, characterized in that, During the process of applying the second radio frequency in the reaction chamber and during the process of applying the first radio frequency in the reaction chamber, the vacuum level in the reaction chamber is adjusted to a preset vacuum level, the preset vacuum level being in the range of 4 to 8 Tols.

6. The electrostatic neutralization method based on PECVD according to claim 1, characterized in that, The process of applying the second radio frequency in the reaction chamber is synchronized with the process of moving the heater base in the reaction chamber, in which the wafer is placed, downward.

7. The electrostatic neutralization method based on PECVD according to claim 1, characterized in that, The step of moving the heater base in the reaction chamber, where the wafer is placed, downward includes: The heater base is driven to move downwards by 50 to 70 millimeters via a lifting mechanism.

8. The electrostatic neutralization method based on PECVD according to claim 1, characterized in that, The process of introducing purge gas into the reaction chamber lasts for 15 seconds or more.

9. The electrostatic neutralization method based on PECVD according to claim 1, characterized in that, The power of the first radio frequency ranges from 300 to 1500 watts, and the frequency is 13.56 MHz.

10. A static neutralization device based on PECVD, characterized in that, include: The first radio frequency application module applies a first radio frequency to the reaction chamber to ionize the continuously introduced reaction gas in the reaction chamber to form plasma, which is then deposited on the wafer surface. The second radio frequency application module applies a second radio frequency to the reaction chamber after stopping the flow of the reaction gas and stopping the application of the first radio frequency in the reaction chamber. The power of the second radio frequency is lower than that of the first radio frequency, and the voltage polarity of the second radio frequency is opposite to that of the first radio frequency. The lifting mechanism moves the heater base in the reaction chamber where the wafer is placed downward, increasing the gap between the wafer and the heater base to facilitate the neutralization of static electricity between the wafer and the heater base by the second radio frequency. The purge module, after the application of the second radio frequency in the reaction chamber is stopped, introduces purge gas into the reaction chamber to clean the wafer surface.

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