Method for monitoring abnormal charge release of lifting pin of electrostatic chuck machine

Abstract

The invention provides a method for monitoring abnormal charge release of a lifting pin of an electrostatic chuck machine, and aims to solve the problems that shutdown and cavity opening are needed and the efficiency is low when the lifting pin is monitored to be abnormal in the prior art. The method comprises the following steps: providing a monitoring wafer, wherein the back surface of the monitoring wafer is provided with a silicon oxide-polycrystalline silicon-silicon oxide back sealing structure; operating the monitoring wafer on an electrostatic chuck machine table to enable the back surface of the monitoring wafer to be adsorbed; performing enhancement treatment on the front surface of the monitored wafer after operation, wherein the enhancement treatment comprises the steps of forming an enhancement oxide layer through a thermal oxidation process and then removing the enhancement oxide layer; performing defect scanning on the front surface of the enhanced monitoring wafer; and judging whether the charge released by the lifting pin of the electrostatic chuck machine table is abnormal or not according to a defect scanning result. According to the method, shutdown for cavity opening is not needed, offline operation can be carried out, the abnormal lifting pin can be effectively detected and positioned, the detection efficiency and the equipment utilization rate can be remarkably improved, predictive maintenance can be achieved, and the product yield can be guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor technology, and in particular to a method for monitoring abnormal release of charges by lift pins of an electrostatic chuck machine. BACKGROUND

[0002] Electrostatic chucks (ESC) are widely used in semiconductor manufacturing equipment (e.g. various models of wafer factories), which utilize the principle of Coulomb attraction to achieve the fixation of wafers. In the process of semiconductor manufacturing, wafers need to be accurately positioned and stably adsorbed on the surface of the electrostatic chuck to ensure the smooth progress of subsequent processes.

[0003] Lift pins are key components in the electrostatic chuck system, responsible for the vertical lifting of wafers on the surface of the electrostatic chuck to facilitate the taking and placing of wafers by mechanical arms or other conveying devices. The lifting action of the lift pins is usually controlled by the inflation and deflation process of clean dry air (CDA). When the CDA gas pipeline or related control system is abnormal, such as blockage, leakage or pressure instability, it will directly affect the lifting speed of the lift pins. The abnormality of the lifting speed of the lift pins, especially during the release of the wafers, may affect the normal release of the electrostatic chuck surface charges, resulting in so-called "release charge anomaly". This anomaly may cause potential damage or contamination on the wafer surface, affecting product yield.

[0004] Currently, for the detection of whether the lifting speed of the lift pins on the electrostatic chuck machine is abnormal and the release charge anomaly that may be caused thereby, the conventional method usually relies on equipment downtime (downtime) and opening of the equipment cavity (opening cavity) for physical inspection and measurement. This inspection method not only consumes time, reduces the effective running time (Uptime) of the equipment and affects production efficiency, but also often fails to timely discover potential and occasional problems. In addition, the opening cavity inspection itself may also introduce additional contamination risk.

[0005] Therefore, there is a lack of a method in the prior art that can conveniently and effectively monitor the release charge anomaly of the lift pins of the electrostatic chuck machine without significantly affecting the normal operation of the equipment. SUMMARY

[0006] The technical problem to be solved by the present application is that the prior art has defects in monitoring the abnormal release of charges by the lift pins of an electrostatic chuck (ESC) machine. The current conventional method usually requires the device to be shut down and the chamber to be opened for physical inspection, which not only consumes time and effort, significantly reduces the effective operation time of the device, and affects production efficiency, but also cannot timely discover potential and occasional abnormalities, and the opening of the chamber may also introduce additional contamination risks. Therefore, there is a lack of a method that can conveniently and effectively monitor the abnormal release of charges by the lift pins of an electrostatic chuck machine without interfering with normal production.

[0007] To achieve the above object and other related objects, the present application provides a method for monitoring abnormal release of charges by lift pins of an electrostatic chuck machine, comprising:

[0008] Step one, providing a monitoring wafer, the monitoring wafer being a wafer with a "silicon oxide-polysilicon-silicon oxide" back sealing structure formed on the back surface of the monitoring wafer;

[0009] Step two, performing work on the monitoring wafer on the electrostatic chuck machine so that the back surface of the monitoring wafer is adsorbed by the electrostatic chuck;

[0010] Step three, performing enhancement treatment on the monitoring wafer after the work in step two, the enhancement treatment comprising: forming an enhancement oxide layer on the front surface of the monitoring wafer by thermal oxidation process, and then removing the enhancement oxide layer;

[0011] Step four, performing defect scanning on the front surface of the monitoring wafer after the enhancement treatment in step three;

[0012] Step five, judging whether there is an abnormal release of charges by the lift pins of the electrostatic chuck machine according to the result of the defect scanning.

[0013] Preferably, in step one, the back sealing structure comprises a first silicon oxide layer, a polysilicon layer and a second silicon oxide layer stacked in sequence on the silicon substrate of the back surface of the monitoring wafer.

[0014] Preferably, in step one, the thickness of the first silicon oxide layer is to

[0015] Preferably, in step one, the thickness of the polysilicon layer is to

[0016] Preferably, in step one, the thickness of the second silicon oxide layer is to

[0017] Preferably, in step three, the thermal oxidation process is performed in a furnace tube.

[0018] Preferably, in step three, the enhancement oxide layer is an oxide liner layer.

[0019] Preferably, in step three, the oxide liner layer has a thickness of to

[0020] Preferably, in step three, the operation of removing the enhancement oxide layer is performed by a wet etching process.

[0021] Preferably, in step five, when a lattice defect is detected on the front side of the monitoring wafer, it is determined that the lift pin of the electrostatic chuck machine releases abnormal charge.

[0022] Preferably, it further comprises determining the position of the abnormal lift pin in the electrostatic chuck machine according to the position of the lattice defect on the front side of the monitoring wafer.

[0023] Preferably, the monitoring wafer is a 12-inch wafer.

[0024] Preferably, the method is an offline monitoring method.

[0025] As described above, the method for monitoring abnormal charge release of the lift pin of the electrostatic chuck machine according to the present application has the following beneficial effects:

[0026] The method provided by the present application can effectively and accurately monitor the abnormal condition of the lift pin of the electrostatic chuck machine by using a monitoring wafer with a specific back sealing structure, combined with subsequent enhancement processing and defect scanning, and can locate the abnormal lift pin. The method is simple to operate, does not need to stop the machine and open the cavity, reduces the maintenance cost and the impact on production, and has significant industrial application value. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A schematic diagram of the method for monitoring abnormal charge release of the lift pin of the electrostatic chuck machine according to the present application is shown.

[0028] Figure 2 A schematic diagram of the "silicon oxide-polysilicon-silicon oxide" back sealing structure according to the present application is shown.

[0029] Figure 3 A schematic diagram of the formation of the enhancement oxide layer according to the present application is shown. DETAILED DESCRIPTION

[0030] Following, the embodiments of the present application are illustrated by specific examples, and other advantages and effects of the present application can be easily understood by those skilled in the art from the disclosure of the present specification. The present application can also be implemented or applied by other different specific embodiments, and various modifications or changes can be made to the details in the present specification based on different views and applications without departing from the spirit of the present application.

[0031] The present application discloses a method for monitoring the abnormal charge release of electrostatic chuck machine lifting pins through a specific structure, which can effectively and conveniently monitor the working state of the electrostatic chuck machine lifting pins in an offline state, timely find the abnormal charge release problem, avoid the disadvantages of traditional methods requiring shutdown and cavity inspection, improve the predictability and efficiency of equipment maintenance, and help to ensure product yield.

[0032] The method comprises the following steps:

[0033] Step one, providing a monitoring wafer, the monitoring wafer is a wafer with a "silicon oxide-polysilicon-silicon oxide" back sealing structure, and the "silicon oxide-polysilicon-silicon oxide" back sealing structure is formed on the back surface of the monitoring wafer. The "silicon oxide-polysilicon-silicon oxide" back sealing structure is more sensitive to the charge change generated by the electrostatic chuck during the adsorption and release of the wafer, and when the lifting pin releases abnormal charge, it is easy to produce subtle changes in the structure or its adjacent wafer area which can be enhanced and detected.

[0034] In some embodiments, in step one, the "silicon oxide-polysilicon-silicon oxide" back sealing structure comprises a first oxide layer, a polysilicon layer and a second oxide layer stacked in order on the silicon substrate on the back surface of the monitoring wafer. This specific stack structure, especially the introduction of the polysilicon layer, can form a structure similar to a capacitor with the oxide layer, which is more sensitive to the accumulation and release of charge, so that when the lifting pin releases abnormal charge, it is more likely to leave traces that can be revealed by subsequent processing on the wafer.

[0035] In some embodiments, in step one, the thickness of the first oxide layer is to The first oxide layer with this thickness range can provide good insulation performance and form an effective interface with the polysilicon layer.

[0036] In some embodiments, in step one, the thickness of the polysilicon layer is to The polysilicon layer with this thickness range as an intermediate layer plays an important role in the subsequent abnormality revelation.

[0037] In some embodiments, in step one, the thickness of the second oxide layer is to The second oxide layer in this thickness range also helps the electrical properties and stability of the overall backside encapsulation structure.

[0038] In some embodiments, in step one, the monitoring wafer is a 12-inch wafer. This makes the present method directly applicable to the current mainstream 12-inch wafer production line, with good compatibility and practicality.

[0039] In step two, the monitoring wafer is subjected to operation on an electrostatic chuck machine, so that the backside of the monitoring wafer is adsorbed by the electrostatic chuck. This step simulates the normal adsorption process of the wafer on the electrostatic chuck in actual production, ensuring that the monitoring result can truly reflect the performance of the electrostatic chuck in the working state. By allowing the wafer backside with a specific backside encapsulation structure to directly contact the electrostatic chuck and undergo the adsorption process, any uneven or abnormal release of charge caused by the lift pins can affect the wafer inside or through the specific structure on the wafer backside.

[0040] In step three, the monitoring wafer subjected to operation in step two is subjected to enhancement treatment, which includes forming an enhancement oxide layer on the front side of the monitoring wafer by a thermal oxidation process, and then removing the enhancement oxide layer. This enhancement treatment step is crucial, as its purpose is to amplify the extremely weak damage, stress or charge residual effects that may occur in the wafer or on the surface due to abnormal release of charge by the lift pins, so as to convert them into physical defects, such as lattice defects, that are more easily detected in subsequent defect scanning. The thermal oxidation and removal process can effectively reveal these potential microscopic changes.

[0041] In some embodiments, in step three, the thermal oxidation process is performed in a furnace tube. Performing thermal oxidation in a furnace tube is a mature semiconductor process that can ensure that the enhancement oxide layer formed has good uniformity and controllable thickness, which is beneficial to the consistency and reliability of the enhancement effect.

[0042] In some embodiments, in step three, the enhancement oxide layer is a pad oxide layer (PAD OX). The pad oxide layer is a commonly used type of oxide layer, and its growth and removal process is very mature and easy to control, making it suitable as a temporary layer in the enhancement treatment.

[0043] In some embodiments, in step three, the thickness of the pad oxide layer is to The pad oxide layer in this thickness range can generate sufficient stress or reaction on the wafer surface during the thermal oxidation process, while it is also relatively easy to control when removed subsequently, which helps to optimize the defect revealing effect.

[0044] In some embodiments, in step three, the operation of removing the oxide layer for enhancement is performed by a wet etching process. Wet etching is a selective, relatively low cost and less damaging to the underlying silicon substrate removal method, which is suitable for removing the oxide pad layer for enhancement, thereby exposing the defects formed on the front side of the wafer due to anomalies.

[0045] Step four, performing defect scanning on the front side of the monitoring wafer after the enhancement process in step three. By scanning the front side of the monitoring wafer using conventional defect scanning equipment (such as optical scattering or electron beam based defect detection systems), physical defects that appear after the enhancement process can be identified.

[0046] Step five, based on the results of the defect scanning, determining whether the lift pins of the electrostatic chuck machine release charge abnormally. If a certain pattern or number of defects, especially lattice defects, are observed in the defect scanning results, it can be determined that the lift pins of the electrostatic chuck machine release charge abnormally.

[0047] In some embodiments, in step five, when lattice defects are detected on the front side of the monitoring wafer, it is determined that the lift pins of the electrostatic chuck machine release charge abnormally. Lattice defects are usually caused by local stress or uneven charge, which damages the silicon crystal structure, and is a typical manifestation of abnormal lift pin charge release on the monitoring wafer after a specific back sealing structure and enhancement process. The presence of such defects directly indicates that there may be a problem with the lift pins.

[0048] In some embodiments, it further includes determining the location of the abnormal lift pins in the electrostatic chuck machine based on the location of the lattice defects on the front side of the monitoring wafer. Since the lift pins on the electrostatic chuck usually have fixed arrangement positions, the location of the lattice defects appearing on the monitoring wafer often corresponds to the location of the abnormal lift pins below. By analyzing the defect map, the specific lift pin or pins that have problems can be accurately located, which provides extremely valuable accurate information for subsequent equipment maintenance and component replacement, significantly improves the targeting and efficiency of maintenance, shortens the equipment downtime, and avoids unnecessary inspection or replacement of the entire electrostatic chuck or all lift pins.

[0049] In some embodiments, the method is an offline monitoring method. This means that the monitoring process can be carried out when the equipment is not performing normal production tasks (for example during scheduled maintenance or when the equipment is idle), so as not to interfere with the normal production plan. This offline monitoring method greatly improves the flexibility of operation, so that the factory can arrange the monitoring frequency according to its own needs, realize the regular "physical examination" of the electrostatic chuck state, help to realize predictive maintenance, find potential problems in advance, prevent large-scale production accidents or product quality problems caused by sudden failure of lifting pins, and ultimately help to reduce production costs and improve overall production stability.

[0050] In summary, the method provided by the present application can effectively and accurately monitor the abnormal situation of the electrostatic chuck machine lifting pin releasing charge by using the monitoring wafer with a specific back sealing structure, combined with subsequent enhancement processing and defect scanning, and can locate the abnormal lifting pin. The method is simple to operate, does not need to stop the machine and open the cavity, reduces the maintenance cost and the influence on production, and has significant industrial application value.

[0051] It should be noted that the diagrams provided in the embodiments only illustrate the basic concept of the present application in a schematic manner, and only show the components related to the present application in the diagrams, not the number, shape and size of the components when actually implemented. The actual implementation of each component may be arbitrarily changed in shape, number and proportion, and the component layout pattern may be more complex.

[0052] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical idea disclosed by the present application should be covered by the claims of the present application.

Claims

1. A method for monitoring abnormal charge release from the lifting pins of an electrostatic chuck machine, characterized in that, At least including: Step 1: Provide a monitoring wafer, wherein the monitoring wafer is a wafer with a "silicon oxide-polysilicon-silicon oxide" back cover structure, wherein the "silicon oxide-polysilicon-silicon oxide" back cover structure is formed on the back side of the monitoring wafer; Step 2: The monitoring wafer is operated on the electrostatic chuck machine so that the back side of the monitoring wafer is attracted by the electrostatic chuck; Step 3: Perform enhancement processing on the monitoring wafer after Step 2. The enhancement processing includes: forming an enhancement oxide layer on the front side of the monitoring wafer through a thermal oxidation process, and then removing the enhancement oxide layer. Step 4: Perform defect scanning on the front side of the monitoring wafer after the enhancement process in Step 3; Step 5: Based on the results of the defect scan, determine whether there is any abnormality in the charge release of the lifting pin of the electrostatic chuck machine.

2. The method for monitoring abnormal charge release from the lifting pin of an electrostatic chuck machine according to claim 1, characterized in that: In step one, the back sealing structure includes a first oxide layer, a polycrystalline silicon layer, and a second oxide layer stacked sequentially on the silicon substrate on the back side of the monitoring wafer.

3. The method for monitoring abnormal charge release from the lifting pin of an electrostatic chuck machine according to claim 2, characterized in that: In step one, the thickness of the first oxide layer is to 4. The method for monitoring abnormal charge release from the lifting pin of an electrostatic chuck machine according to claim 2, characterized in that: In step one, the thickness of the polycrystalline silicon layer is to 5. The method for monitoring abnormal charge release from the lifting pin of an electrostatic chuck machine according to claim 2, characterized in that: In step one, the thickness of the second oxide layer is to 6. The method for monitoring abnormal charge release from the lifting pin of an electrostatic chuck machine according to claim 1, characterized in that: In step three, the thermal oxidation process is carried out in a furnace tube.

7. The method for monitoring abnormal charge release from the lifting pin of an electrostatic chuck machine according to claim 6, characterized in that: In step three, the reinforcing oxide layer is an oxide pad layer.

8. The method for monitoring abnormal charge release from the lifting pin of an electrostatic chuck machine according to claim 7, characterized in that: In step three, the thickness of the oxide liner layer is to 9. The method for monitoring abnormal charge release from the lifting pin of an electrostatic chuck machine according to claim 7 or 8, characterized in that: In step three, the removal of the reinforcing oxide layer is performed by a wet etching process.

10. The method for monitoring abnormal charge release from the lifting pin of an electrostatic chuck machine according to claim 1, characterized in that: In step five, when a lattice defect is detected on the front side of the monitored wafer, it is determined that there is an abnormality in the charge release of the lifting pin of the electrostatic chuck.

11. The method for monitoring abnormal charge release from the lifting pin of an electrostatic chuck machine according to claim 1, characterized in that: It also includes determining the position of the lifting pin that caused the abnormality in the electrostatic chuck machine based on the position of the lattice defect on the front side of the monitored wafer.

12. The method for monitoring abnormal charge release from the lifting pin of an electrostatic chuck machine according to claim 1, characterized in that: The monitoring wafer is a 12-inch wafer.

13. The method for monitoring abnormal charge release from the lifting pin of an electrostatic chuck machine according to claim 1, characterized in that: The method described is an offline monitoring method.

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