TWI866084B - Apparatus and method for polishing silicon wafer edge - Google Patents

Abstract

The embodiment of the present invention discloses an apparatus and method for edge polishing of a silicon wafer, the apparatus comprising: a robot for conveying a silicon wafer; a controller for controlling the robot to convey the silicon wafer to a desired position corresponding to a target morphology of the silicon wafer according to a standard position, so that the edge polishing of the silicon wafer is performed at the desired position.

Description

Apparatus and method for polishing silicon wafer edge

The present invention relates to the field of semiconductor processing technology, and more particularly to an apparatus and method for polishing the edge of a silicon wafer.

Semiconductor silicon wafers are the main substrate material for manufacturing ultra-large integrated circuits. With the rapid development of the semiconductor industry, the precision requirements for substrate materials are becoming higher and higher, especially the outer surface state of silicon wafers is becoming more and more stringent. Generally, the outer surface of the silicon wafer needs to be polished during substrate processing to ensure that no slip lines or epitaxial layer errors are generated at the edge of the silicon wafer during the epitaxial process, thereby improving the yield of epitaxial wafers or devices.

With the improvement of precision requirements, some edge polishing problems that were not paid attention to before have gradually been discovered and become the main factors affecting product quality and yield. How to ensure the edge morphology of silicon wafers is a typical example of such problems.

After the silicon wafer is chamfered, the process that affects the edge morphology of the silicon wafer includes at least the edge polishing process. Therefore, in order to meet the edge morphology requirements when the silicon wafer product is shipped, it is necessary to maintain the chamfered part of the silicon wafer after edge polishing. The edge polishing process of the silicon wafer includes V-notch polishing and round edge polishing. The round edge polishing here refers to the polishing of the edge contour of the silicon wafer except the V-notch. When performing circular edge polishing, the positioning of the silicon wafer to be polished relative to the polishing head will determine the topography and size of the silicon wafer after polishing. Therefore, how to accurately position the silicon wafer to be polished is a technical problem that needs to be solved urgently in this field.

In view of this, the embodiments of the present invention are intended to provide an apparatus and method for polishing the edge of a silicon wafer, which can position the silicon wafer to be polished at a desired position corresponding to the target morphology of the silicon wafer, thereby achieving precise positioning of the silicon wafer to meet the requirements for the morphology of the product after polishing.

The technical solution of the embodiment of the present invention is implemented as follows: In the first aspect, the embodiment of the present invention provides a device for polishing the edge of a silicon wafer, the device comprising: A manipulator for conveying a silicon wafer; A controller, the controller being used to control the manipulator to convey the silicon wafer to a desired position corresponding to the target morphology of the silicon wafer according to a standard position, so that the edge of the silicon wafer is polished at the desired position.

In a second aspect, an embodiment of the present invention provides a method for edge polishing of a silicon wafer, the method comprising: Fixing a silicon wafer on a robot; Controlling the robot to transfer the silicon wafer to a desired position corresponding to a target morphology of the silicon wafer according to a standard position, so that the edge polishing of the silicon wafer is performed at the desired position.

The embodiment of the present invention provides an apparatus and method for polishing the edge of a silicon wafer; the apparatus includes a robot arm and a controller for conveying a silicon wafer. The controller controls the movement of the robot arm to place the silicon wafer at a desired position corresponding to the target morphology of the silicon wafer, thereby enabling the polished silicon wafer to meet different morphology requirements and avoiding the occurrence of silicon wafer damage caused by manual adjustment of the robot arm.

The technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiment of the present invention.

Refer to FIG1 , which shows an edge polishing device 1 for a silicon wafer W in a conventional technical solution. As can be seen from FIG1 , the edge polishing device 1 mainly includes: a vacuum suction cup 10, a round edge polishing drum 20, a plurality of polishing heads 30, and a liquid supply pipeline 40; wherein, the vacuum suction cup 10 is mainly used to absorb and fix the silicon wafer W to be edge polished; the round edge polishing drum 20 is mainly used to cooperate with the vacuum suction cup 10 to complete the polishing of the edge of the silicon wafer W. Specifically, during the edge polishing process of the silicon wafer W, the silicon wafer W is fixed by the vacuum suction cup 10, and the vacuum suction cup 10 moves toward the direction close to the round-edge polishing drum 20, so that the edge of the silicon wafer W can abut against the polishing head 30. During the edge polishing process of the silicon wafer W, the polishing liquid is directly dripped onto the center of the upper surface of the silicon wafer W through the liquid supply pipe 40 arranged at the center position of the round-edge polishing drum 20. At the same time, the round-edge polishing drum 20 rotates around the center axis X, and the vacuum suction cup 10 drives the silicon wafer W to rotate around the center axis X as well, so that the polishing liquid on the upper surface of the silicon wafer W flows to the edge of the silicon wafer W under the action of centrifugal force, and flows to between the silicon wafer W and the polishing head 30. In this case, the high-speed rotation of the round-edge polishing drum 20 will also apply pressure to the silicon wafer W and maintain relative rotation with the silicon wafer W, thereby achieving polishing of the edge of the silicon wafer W.

Different applications have different requirements for the morphology of silicon wafers. FIG2 shows a polishing head 30 and a silicon wafer W of an edge polishing device 1 in a conventional technical solution, wherein the polishing head 30 can be divided into three groups, which are respectively used to polish the upper edge, the lower edge and the circumferential edge of the silicon wafer W. In the silicon wafer manufacturing process, the tilt angle of the polishing head for polishing the upper edge and the lower edge can be set according to the target edge morphology to obtain a silicon wafer that meets the requirements.

In order to meet the edge morphology requirements, in addition to setting the angle of the polishing head, attention should also be paid to the positioning of the silicon wafer relative to the polishing head. In FIG2, two positionings of the silicon wafer W relative to the polishing head 30 are shown with solid lines and dashed lines, respectively. In FIG3, the silicon wafer processed by the two positioning methods shown in FIG2 is shown correspondingly. By comparison, it can be seen that even if the setting angle of the polishing head is the same, but the positioning of the silicon wafer relative to the polishing head is different, the morphological dimensions of the obtained silicon wafer are also different, for example, the dimensions A1, B1, A2, and B2 are all different.

At present, silicon wafers are usually transported from other stations to the edge polishing station by robots. However, on the one hand, the robot cannot accurately transport the silicon wafer to the right position. On the other hand, the posture and position of the robot are often fixed. If silicon wafers with different edge morphologies need to be produced, manual intervention in the positioning of the silicon wafer is required. However, the accuracy of manual intervention is too low, which may cause the silicon wafer to be crushed by the polishing head during polishing.

Based on the above problems, see FIG. 4 , which shows a device 2 for edge polishing of a silicon wafer W provided by an embodiment of the present invention, the device 2 comprising: A manipulator 201 for conveying a silicon wafer W; A controller 202, the controller being used to control the manipulator 201 to convey the silicon wafer W to a desired position DE corresponding to the target morphology of the silicon wafer according to a standard position SD, so that the silicon wafer W is edge polished at the desired position DE.

As shown in FIG4 , the device 2 provided by the embodiment of the present invention includes a manipulator 201 and a controller 202, and a silicon wafer W to be edge-polished can be fixed on the manipulator 201. As an example, referring to FIG4 , the manipulator 201 can be provided with a clamping portion 2011 for holding the silicon wafer by clamping the circumferential edge of the silicon wafer W. For example, the clamping portion 2011 can clamp the circumferential edge of the silicon wafer W at two central symmetrical positions along the diameter direction of the silicon wafer. Of course, it can be understood that the manipulator 201 can also be provided with a negative pressure adsorption device to hold the silicon wafer by adsorbing the main surface of the silicon wafer. The manipulator 201 can carry the silicon wafer W and transfer it to the position to be polished on the polishing table PL. The movement of the robot 201 is controlled by the controller 202 without the need for human intervention. A standard position SD can be set on the polishing table PL. For example, the position of the silicon wafer corresponding to the normal morphology of the silicon wafer can be set as the standard position SD. When it is necessary to produce a silicon wafer with a normal morphology, the controller can control the robot to place the silicon wafer to be edge-polished at the standard position SD, and the silicon wafer will be edge-polished at the standard position SD, thereby obtaining a silicon wafer with a normal morphology. In this case, the standard position SD coincides with the desired position DE; when it is necessary to manufacture a silicon wafer with a special morphology, the silicon wafer to be edge-polished needs to be placed at a position deviated from the standard position SD. In this regard, the controller controls the robot 201 to transfer the silicon wafer W to the desired position DE corresponding to the target morphology of the silicon wafer according to the standard position SD.

The embodiment of the present invention provides a device 2 for polishing the edge of a silicon wafer; the device 2 includes a robot 201 for conveying a silicon wafer and a controller 202. The controller controls the movement of the robot to place the silicon wafer at a desired position corresponding to the target morphology of the silicon wafer, thereby enabling the polished silicon wafer to meet different morphology requirements and avoiding the occurrence of silicon wafer damage caused by manual adjustment of the robot.

Regarding the specific operation of the robot 201, according to an optional embodiment of the present invention, after the controller 202 transfers the silicon wafer W to the standard position SD, it transfers the silicon wafer W to the desired position DE according to the offset of the desired position DE relative to the standard position SD. In other words, the transfer of the silicon wafer W can be divided into two steps: the first step is to transfer the silicon wafer W to the standard position SD, and the second step is to transfer the silicon wafer from the standard position SD to the desired position DE. Since the size difference between silicon wafers with different morphologies is not large, the distance between the desired position DE and the standard position SD is also small. If the silicon wafer is transferred in two steps, the distance of moving the silicon wafer in the first step is relatively large. For example, as shown in Figure 4, the silicon wafer can be moved from the waiting position WP to the standard position SD. For this step, the movement speed of the robot can be set to be faster; the distance of moving the silicon wafer in the second step is relatively small. In fact, it can be considered as a fine-tuning of the position of the silicon wafer. The movement speed of this step can be slower so that the silicon wafer can be moved to the desired position DE more accurately. This can improve the efficiency of transferring the silicon wafer as a whole and improve the accuracy of the final positioning of the silicon wafer.

In order to realize automatic control of the manipulator 201, optionally, referring to FIG5 , the device 2 further includes: a processor 203 configured to communicate with the controller, the processor 203 is used to obtain the offset of the desired position DE relative to the standard position SD and send it to the controller 202, thereby, there is no need to manually input the movement amount of the manipulator, only the target morphology and the calculation model need to be input into the processor, and the processor can convert the target morphology into the movement amount of the manipulator and send it to the controller to control the manipulator to move the corresponding amount.

In actual operation, in order to be able to transport the silicon wafer more accurately, the robot can be set to move only in a single straight line direction. As a demonstration, as shown in Figure 4, the device 2 shown also includes a guide rod 204. The robot 201 and the controller 202 are set to move only along the guide rod 204. As far as Figure 4 is concerned, they can only move in the horizontal direction and cannot move in other directions. In this way, the guide rod can be set in an appropriate position in advance, so that the silicon wafer can be transported to the desired position DE by only adjusting the moving distance of the robot along the guide rod 204. In this case, as a specific implementation form, when the controller 202 controls the robot 201 to move toward the polishing head (not shown in FIG. 4 ), the offset is a positive value; when the controller 202 controls the robot 201 to move away from the polishing head, the offset is a negative value.

In addition to controlling the manipulator to move according to the set value, other methods can also be used to control the movement of the manipulator. According to an optional embodiment of the present invention, see Figure 6, the device 2 further includes a sensor 205 that communicates with the controller 202, and the sensor 205 is configured to send a signal to the controller when the silicon wafer W is transferred to the standard position SD, thereby determining whether the silicon wafer reaches the standard position SD based on the detection result of the sensor 205, further improving the accuracy of positioning the silicon wafer.

Regarding the specific implementation form of the sensor, optionally, the sensor 205 is a pair of sensors respectively arranged at the manipulator 201 and the standard position SD. Referring to FIG6 , a first sensor 2051 and a second sensor 2052 are arranged on the manipulator, and a third sensor 2053 and a fourth sensor 2054 are arranged at the corresponding position of the standard position SD. When the manipulator transfers the silicon wafer to the standard position SD, the second sensor 2052 and the fourth sensor 2054 can receive the signals emitted by the first sensor 2051 and the third sensor 2053 respectively, and send signals to the controller at the same time. The controller controls the manipulator to stop moving according to the signals to place the silicon wafer at the standard position SD.

Referring to FIG. 7 , the embodiment of the present invention also provides a method for edge polishing of a silicon wafer, the method comprising: S101, fixing the silicon wafer on a robot; S102, controlling the robot to transfer the silicon wafer to a desired position corresponding to the target morphology of the silicon wafer according to a standard position, so that the edge of the silicon wafer is polished at the desired position.

According to an optional embodiment of the present invention, controlling the robot to transfer the silicon wafer to a desired position corresponding to the target morphology of the silicon wafer according to the standard position includes: after transferring the silicon wafer W to the standard position SD, transferring the silicon wafer W to the desired position DE according to the offset of the desired position DE relative to the standard position SD.

According to an optional embodiment of the present invention, the method further includes obtaining the offset of the desired position DE relative to the standard position SD.

It should be noted that the technical solutions described in the embodiments of the present invention can be combined arbitrarily without conflict.

The above is only a specific implementation of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person of ordinary skill in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the patent application.

S101~S102: Steps 10: Vacuum suction cup 20: Round edge polishing drum 30: Polishing head 40: Liquid supply pipeline 1, 2: Equipment 201: Robot 2011: Clamping part 202: Controller 203: Processor 204: Guide rod 205: Sensor 2051: First sensor 2052: Second sensor 2053: Third sensor 2054: Fourth sensor DE: Expected position PL: Polishing table SD: Standard position W: Silicon wafer WP: Waiting position X: Center axis

Figure 1 is a silicon wafer edge polishing device used in the conventional technology provided by an embodiment of the present invention; Figure 2 is a part of another silicon wafer edge polishing device used in the conventional technology provided by an embodiment of the present invention; Figure 3 is a schematic diagram of the morphology of the silicon wafer after edge polishing; Figure 4 is a schematic diagram of a device for silicon wafer edge polishing provided by an embodiment of the present invention; Figure 5 is a schematic diagram of a device for silicon wafer edge polishing provided by another embodiment of the present invention; Figure 6 is a schematic diagram of a device for silicon wafer edge polishing provided by another embodiment of the present invention; Figure 7 is a flow chart of a method for silicon wafer edge polishing provided by an embodiment of the present invention.

2: Equipment

201: Robotic Arm

2011: Clamping Department

202: Controller

204:Guide rod

DE: Desired position

PL: Polishing table

SD: Standard position

W: Silicon wafer

WP: Waiting position

Claims (9)

A device for polishing the edge of a silicon wafer, the device comprising: a manipulator for conveying a silicon wafer; a controller, the controller being used to control the manipulator to convey the silicon wafer to a desired position corresponding to a target morphology of the silicon wafer according to a standard position, so that the edge of the silicon wafer is polished at the desired position; wherein the standard position is a position corresponding to the conventional morphology of the silicon wafer. The device for polishing the edge of a silicon wafer as described in claim 1, wherein the controller transfers the silicon wafer to the standard position and then transfers the silicon wafer to the desired position according to the offset of the desired position relative to the standard position. The device for polishing the edge of a silicon wafer as described in claim 2, wherein the device further comprises: a processor configured to communicate with the controller, the processor being used to obtain the offset of the desired position relative to the standard position and send it to the controller. The device for polishing the edge of a silicon wafer as described in claim 2, wherein when the controller controls the robot to move toward the polishing head, the offset is a positive value; when the controller controls the robot to move away from the polishing head, the offset is a negative value. An apparatus for polishing the edge of a silicon wafer as described in any one of claims 2 to 4, wherein the apparatus further comprises a sensor communicating with the controller, the sensor being configured to send a signal to the controller when the silicon wafer is transferred to the standard position. The device for polishing the edge of a silicon wafer as described in claim 5, wherein the sensor is a pair of sensors respectively arranged at the robot arm and the standard position. A method for polishing the edge of a silicon wafer, the method comprising: Fix a silicon wafer on a robot; control the robot to transfer the silicon wafer to a desired position corresponding to a target morphology of the silicon wafer according to a standard position, so that the edge of the silicon wafer is polished at the desired position; wherein the standard position is a position corresponding to the conventional morphology of the silicon wafer. The method for polishing the edge of a silicon wafer as described in claim 7, wherein the controlling the robot to transfer the silicon wafer to a desired position corresponding to the target morphology of the silicon wafer according to the standard position comprises: after transferring the silicon wafer to the standard position, transferring the silicon wafer to the desired position according to the offset of the desired position relative to the standard position. A method for polishing a silicon wafer edge as described in claim 8, wherein the method further includes obtaining the offset of the desired position relative to the standard position.