TW202314951A - Wafer dechucking method - Google Patents

Abstract

The present invention discloses a wafer dechucking method, which is used in a wafer processing system and a wafer processing method. The wafer dechucking method of the present invention includes: a polarity reversing step of reversing the polarity of the voltage applied to the chuck; a first transfer step of transferring the wafer supported on the chuck to a first set position by lifting the lift pins accommodated in the chuck from the chuck at a first transfer speed; and a second transfer step of transferring the wafer disposed at the first set position to the second set position higher than the first set position by raising the lift pins at a second transfer speed different from the first transfer speed.

Description

Wafer Release Method

The present invention relates to a wafer release method, and more particularly, to a wafer release method for releasing a wafer from an electrostatic chuck holding a wafer product in a semiconductor manufacturing process system.

Generally, a chuck used in a semiconductor manufacturing process system generates an electrostatic phenomenon when a voltage is applied, thereby fixing a wafer supported on an upper surface thereof.

However, the problem with the above-mentioned electrostatic chuck is that the wafer is fixed by electrostatic force. Therefore, when the lift pin is used to separate the wafer from the chuck, due to the force acting between the chuck and the wafer, The electrostatic force makes it difficult to separate the wafers.

That is, there is a problem that when the wafer is separated from the chuck by supporting the wafer with lift pins, there will be a large resistance due to the electrostatic force between the chuck and the wafer, thus causing the wafer to come off. lift pin.

Therefore, in the past, in order to solve the above-mentioned problems, a method has been developed that reverses the polarity of the voltage applied to the chuck to discharge the residual charge, thereby removing the electrostatic force between the chuck and the wafer to remove the chuck from the chuck. Method for separating wafers.

However, there is a problem that even if the polarity of the voltage applied to the chuck is reversed to discharge the charge, it cannot be completely discharged, so that some electrostatic force remains between the chuck and the wafer. When the wafer is separated, the wafer supported by the lift pins may be detached from the lift pins or tilted, and the wafer may be damaged.

technical problem

The object of the present invention is to provide a method for releasing a wafer, which completely discharges the residual charge between the chuck and the wafer, so as to prevent the phenomenon that the wafer is detached from the lift pin or tilted due to the influence of the residual charge when the wafer is separated, and The problem of wafer damage occurs, and the defective rate can be minimized.

Technical solutions

A wafer releasing method according to an embodiment of the present invention includes: a polarity reversing step of reversing the polarity of a voltage applied to the chuck; and raising lift pins accommodated in the chuck from the chuck at a first transfer speed to a first transfer step in which the wafer supported by the chuck is transferred to a first set position; The second transfer step to the second set position at the first set position.

The second set position may be a position where the wafer is transferred.

The first transfer speed may be slower than the second transfer speed.

The relative ratio of the first transfer speed to the second transfer speed may be 1:2 to 1:5.

The distance from the chuck to the first set position may be shorter than the distance from the chuck to the second set position.

A relative ratio of the first distance from the chuck to the first set position to the second distance from the chuck to the second set position may be 1:4 to 1:6.

The wafer may be continuously moved from the first set position to the second set position.

A wafer releasing method according to another embodiment of the present invention includes: a polarity reversing step of reversing the polarity of a voltage applied to the chuck; raising lift pins accommodated in the chuck from the chuck at a first transfer speed to a first transfer step of transferring the wafer supported by the chuck to a first set position; lowering the lift pin at a third transfer speed to transfer the wafer disposed at the first set position to a second lower position than the first set position A third transfer step at three set positions; and raising the lift pins at a second transfer speed different from the first transfer speed and the third transfer speed to move the wafer disposed at the third set position to a position higher than the first set position The second transfer step of the second set position.

The third transfer speed may be the same speed as the first transfer speed or faster than the first transfer speed.

The relative ratio of the first transfer speed to the second transfer speed may be 1:2 to 1:5, and the relative ratio of the third transfer speed to the second transfer speed may be 1:2 to 1:5.

The third set position may be a position where the wafer is supported on the chuck.

A flow path is formed between the chuck and the wafer when the wafer supported by the chuck is transferred to the first set position, and the wafer placed at the first set position is transferred to the third set position In this case, the fluid supplied from above the wafer and discharged from a position below the wafer can come into contact with the upper surface of the chuck and the lower surface of the wafer while passing through the flow path.

At least one of the first transfer step and the second transfer step may include a plurality of intervals in which the speed can be increased gradually or in intervals.

At least before the wafer is moved to a position above the first set position, the fluid supplied from above the wafer may pass through the wafer and be discharged from a position below the wafer.

When the transfer speed of the wafer is changed, at least one of the volume and the pressure of the fluid can be changed.

The effect of the invention

According to an embodiment of the present invention, when the wafer is separated from the chuck, the wafer is slowly and steadily transferred to minimize the influence of the residual charge remaining between the wafer and the chuck on the wafer, thereby preventing Due to the influence of residual charge, the phenomenon of wafer detaching from lift pins or tilting and wafer damage occurs, and the defective rate of wafers is minimized.

In addition, when the wafer is slowly separated from the chuck, a flow path is formed between the chuck and the wafer so that the fluid supplied into the chamber flows between the chuck and the wafer, so that residual charges can be completely discharged.

At the same time, when the wafer is moved to the first set position which is not affected by the electrostatic force, the wafer is moved to the second set position at a faster speed to shorten the process time, thereby increasing the throughput. ) loss is minimized.

The effects of the present invention are not limited to the above-mentioned exemplary contents, but more diverse effects are included in the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily implement.

The present invention can be realized in various forms and is not limited to the embodiments described here.

Referring to FIG. 1 , a wafer release process according to an embodiment of the present invention is performed by a wafer processing apparatus 100 of a semiconductor manufacturing system.

The wafer processing apparatus 100 is configured to be able to carry in and out the wafer W through a robot arm (not shown), and includes a chamber 10 as a space for processing the wafer W. The chuck 20 that fixes or unfixes the wafer W according to the polarity of the applied DC voltage, and the lift pins 30 housed inside the chuck 20 and configured to lift the wafer W up and down. However, the wafer processing apparatus 100 is not limited thereto, and may further include various components.

A wafer releasing method according to an embodiment of the present invention will be described in more detail.

The wafer release method according to an embodiment of the present invention may include a polarity inversion step S110 , a first transfer step S120 , and a second transfer step S130 .

Referring to part (a) of FIG. 1 and FIG. 2 , the wafer processing apparatus 100 may perform a polarity inversion step S110 of inverting the polarity of the voltage applied to the chuck 20 when the wafer W processing step is completed.

That is, the wafer processing apparatus 100 reverses the polarity of the voltage applied to the chuck 20 so that the wafer W fixed on the chuck 20 can be separated from the chuck 20 after the wafer W processing step is completed. For example, the polarity of the DC voltage applied to the chuck 20 before performing the wafer W processing step may be +, and the polarity of the DC voltage applied to the chuck 20 after the wafer W processing step may be −. However, the polarity of the DC voltage applied to the chuck 20 before performing the processing step of the wafer W and the polarity of the DC voltage applied to the chuck 20 after performing the processing step of the wafer W are not limited thereto, and may be opposite to each other. polarity for application.

Referring to part (b) of FIG. 1 and FIG. 2 , when the polarity of the voltage applied to the chuck 20 is reversed, the wafer processing apparatus 100 can make the lift pins 30 accommodated in the chuck 20 move from the chuck 20 at a first transfer speed. The tray 20 is raised to perform the first transfer step S120 of transferring the wafer W supported by the chuck 20 to the first set position P1. Although not shown in the figure, a driving device (not shown) combined with the lift pin 30 and configured to lift the lift pin 30 may be further configured. For example, the drive means may be implemented as an actuator such as a motor or a cylinder.

Referring to part (c) of FIG. 1 and FIG. 2, when the wafer W is transferred to the first set position P1, the wafer processing apparatus 100 can raise the lift pin 30 at a second transfer speed different from the first transfer speed, To execute the second transfer step S130 of transferring the wafer W disposed at the first set position P1 to a second set position P2 higher than the first set position P1.

That is, as shown in FIG. 1 , when the wafer W is moved to the first set position P1, the wafer processing apparatus 100 raises the lift pins 30 at a second transfer speed different from the first transfer speed so as to move the wafer W disposed at the first set position P1. The wafer W at the first set position P1 is transferred to the position where the wafer W is transported by a robotic arm (not shown), that is, the second set position P2.

Therefore, in this embodiment, when the wafer W is separated from the chuck 20, the wafer W is slowly and stably transferred so that the influence of the electrostatic force remaining between the wafer W and the chuck 20 on the wafer W Minimization, thus preventing the phenomenon that the wafer W is detached from the lift pin 30 or tilted due to the influence of electrostatic force and the problem that the wafer W is damaged, and the defective rate of the wafer can be minimized.

At this time, the first transfer speed of the lift pins 30 may be slower than the second transfer speed of the lift pins 30 .

That is to say, in order to prevent the influence of the residual charge remaining between the wafer W and the chuck 20 from affecting the wafer W, the wafer processing apparatus 100 supports the wafer W on the chuck at a first transfer speed relatively slower than the second transfer speed. After the wafer W on the tray 20 is moved to the first set position P1, when the wafer W reaches the first set position P1, in order to execute the process faster, the wafer W is moved to the second set position P2 at the second transfer speed .

In more detail, the relative ratio of the first transfer speed to the second transfer speed may be 1:2 to 1:5. For example, the driving pulses of the driving device (not shown) for lifting and lowering the lift pin 30 at the first transfer speed can be set to 8000 to 15000. In addition, the driving pulses of the driving device (not shown) for raising and lowering the lift pins 30 at the second transfer speed can be set to 16000 to 75000.

In addition, the first distance _d1 of the chuck 20 to the first set position P1 may be formed to be shorter than the second distance _d2 of the chuck 20 to the second set position P2. For example, the first set position P1 may be a position where the wafer W supported by the lift pins 30 is lifted from the chuck 20 at the first transfer speed for 5 seconds to 20 seconds.

In more detail, the relative ratio of the first distance d ₁ from the chuck 20 to the first set position P1 to the second distance d ₂ from the chuck 20 to the second set position P2 may be 1:4 to 1:6.

At this time, the wafer W is continuously moved from the first set position P1 to the second set position P2. That is, when transferring the wafer W from the first set position P1 to the second set position P2, the transfer may be performed by changing the transfer speed without stopping.

Referring to FIGS. 1 and 3 , at least one of the process in which the wafer W is transferred from the chuck 20 to the first set position P1 and the process in which the wafer W is transferred from the first set position P1 to the second set position P2 may include The transfer speed of the wafer W can be changed to a plurality of intervals gradually or in intervals.

That is, during at least one of the process of transferring the wafer W from the chuck 20 to the first set position P1 and the process of transferring the wafer W from the first set position P1 to the second set position P2, the lift pins 30 can gradually increase the transfer speed of the wafer W, or the lift pins 30 can increase the transfer speed of the wafer W in sections when the transfer speed of the wafer W is divided into a plurality of sections and the sections are different from each other.

For example, referring to FIG. 3 which shows the process of moving from the first set position P1 to the second set position P2, the lift pins 30 can gradually increase the speed of the rise to move the wafer W disposed at the first set position P1 more. Quickly move to the second set position P2. For reference, in FIG. 3 , the arrows shown on both sides of the wafer W indicate the transfer speed of the wafer W, and at this time, the thickness of the arrows indicates how fast the transfer speed is. That is to say, it can be shown that the transfer speed of the wafer W shown in part (b) of FIG. 3 is faster than the transfer speed of the wafer W shown in part (a) of FIG. The transfer speed of the wafer W shown in FIG. 3 is faster than the transfer speed of the wafer W shown in part (b) of FIG. 3 .

Therefore, in this embodiment, when the wafer W is moved to the first set position P1 which is not affected by the electrostatic force, the wafer W can be continuously moved to the second set position P2 at a faster speed to shorten the time. Process time, thereby minimizing losses in throughput.

In addition, a plurality of intervals in which the transfer speed of the wafer W can be increased gradually or in intervals may be included so that the wafer W can be transferred stably.

On the other hand, the fluid supplied from above the wafer W may pass through the wafer W and be discharged from a position below the wafer W. At this time, the fluid may be supplied at least before the wafer W is moved to a position above the first set position P1, and may also be supplied while the wafer W is being moved to the second set position P2 as needed.

At this time, the fluid is discharged in combination with the residual charge remaining between the wafer W and the chuck 20 , so that the residual charge can be completely discharged.

For example, the fluid may be an inert gas or a gas close to an inert gas. Specifically, the fluid may be formed of argon (Ar) series or dinitrogen (N ₂ ) series.

On the other hand, when the transfer speed of the wafer W is changed, at least one of the volume and the pressure of the fluid supplied to the inside of the chamber 10 may be changed. For example, the capacity of the fluid may vary from 50 seem to 500 seem. In addition, the pressure of the fluid can be changed within the range of 5mT to 1000mT.

Specifically, when the transfer speed of the wafer W increases, at least one of the volume and the pressure of the fluid may decrease in size. For example, the wafer W is transferred from the first set position P1 compared to the magnitude of at least one of the volume and the pressure of the fluid during the process of the wafer W being spaced apart from the chuck 20 and being moved to the first set position P1. At least one of the volume and the pressure of the fluid may be smaller on the way to the second set position P2.

Thereby, as the transfer speed of the wafer W increases, at least one of the volume and the pressure of the fluid can be reduced, so that the wafer W can be transferred stably.

Hereinafter, a method for releasing a wafer according to another embodiment of the present invention will be described.

For ease of description, for each component used to describe the wafer release method of another embodiment of the present invention, the same element symbols as those used when describing the wafer release method of one embodiment of the present invention will be used, and The same or repeated explanations will be omitted.

The wafer release method according to another embodiment of the present invention may include a polarity inversion step S210 , a first transfer step S220 , a third transfer step S230 and a second transfer step S240 .

Referring to part (a) of FIG. 4 and FIG. 5 , the wafer processing apparatus 100 may perform a polarity inversion step S210 of inverting the polarity of the voltage applied to the chuck 20 when the wafer W processing step is completed.

Referring to part (b) of FIG. 4 and FIG. 5, when the polarity of the voltage applied to the chuck 20 is reversed, the wafer processing apparatus 100 can make the lift pins 30 accommodated in the chuck 20 move from the chuck 20 at a first transfer speed to The tray 20 is raised to perform the first transfer step S220 of transferring the wafer W supported by the chuck 20 to the first set position P1.

Referring to part (c) of FIG. 4 and FIG. 5, when the wafer W is transferred to the first set position P1, the wafer processing apparatus 100 may lower the lift pins 30 at a third transfer speed, so as to implement the configuration at the first position. The wafer W at the set position P1 is transferred to a third transfer step S230 at a third set position P3 lower than the first set position P1.

Referring to part (d) of FIG. 4 and FIG. 5 , when the wafer W is moved to the third set position P3, the wafer processing apparatus 100 can make the lift pin 30 move at a second speed different from the first transfer speed and the third transfer speed. The second transfer speed is increased to execute the second transfer step S240 of transferring the wafer W disposed at the third set position P3 to the second set position P2 higher than the first set position P1.

At this time, the third transfer speed of the lift pins 30 may be the same speed as or faster than the first transfer speed of the lift pins 30 . In addition, the first transfer speed of the lift pins 30 and the third transfer speed of the lift pins 30 may be slower than the second transfer speed of the lift pins 30 .

In more detail, the relative ratio of the first transfer speed to the second transfer speed may be 1:2 to 1:5, and the relative ratio of the third transfer speed to the second transfer speed may be 1:2 to 1:5.

In addition, the first set position P1 may be a position where the wafer W is not affected by the residual charge remaining between the wafer W and the chuck 20, and the second set position P2 may be set by a mechanical arm (not shown) The position where the wafer W is transferred, the third set position P3 may be a position where the wafer W is supported on the chuck 20 .

That is, as shown in FIG. 4 , when the wafer W processing process ends, in order to prevent the influence of the residual charge remaining between the wafer W and the chuck 20 from affecting the wafer W, the wafer processing apparatus 100 will The wafer W supported by the chuck 20 is moved to the first set position P1 at the first transfer speed relatively slower than the second transfer speed. Then, when the wafer W reaches the first set position P1, the wafer processing apparatus 100 moves the wafer W placed at the first set position P1 to the first transfer position in such a manner that the wafer W is supported on the chuck 20 . The same speed or a third transport speed faster than the first transport speed is used to move to the third set position P3. Then, when the wafer W reaches the third set position P3, in order to execute the process faster, the wafer processing apparatus 100 will place the wafer W placed at the third set position P3 at a speed faster than the first transfer speed and the third transfer speed. The second fast transfer speed moves to the second set position P2 for transferring the wafer W.

Therefore, in this embodiment, when the wafer W is transferred to the first set position P1 or the third set position P3, it is slowly moved to adjust to make the wafer W more stably supported on the lift pins 30, thereby enabling The wafer W is stably raised to the second set position P2.

In addition, in this embodiment, before the wafer W supported by the chuck 20 is transferred to the second set position P2, it is raised to the first set position P1 and then lowered to the third set position P3, so that the The residual charges remaining between the wafer W and the chuck 20 are completely discharged.

In addition, in this embodiment, a flow path FP is formed between the chuck 20 and the wafer W during the transfer of the wafer W supported by the chuck 20 to the first set position P1, and the During the process of transferring the wafer W at the first set position P1 to the third set position P3, when the fluid supplied from above the wafer W and discharged from a position lower than the wafer W passes through the flow path FP, it is in contact with the chuck 20. The upper surface is in contact with the lower surface of the wafer W, and, due to the wafer W being transferred to the third set position P3, the height of the flow path FP is gradually reduced, so that the flow of the fluid is accelerated, and thus the wafer W can be moved faster. The residual charge between the chuck 20 and the chuck 20 is discharged.

In addition, in this embodiment, when the wafer W is transferred to the second set position P2, it can be transferred at a relatively faster speed than when the wafer W is transferred to the first set position P1 and the third set position P3. , to shorten the process time.

Although not shown, the distance from the chuck 20 to the first set position P1 may be formed shorter than the distance from the chuck 20 to the second set position P2.

In addition, the process of transferring the wafer W from the chuck 20 to the first set position P1, the process of transferring the wafer W from the first set position P1 to the third set position P3, and the transfer of the wafer W from the third set position P3 At least one of the steps to the second set position P2 may include a plurality of intervals in which the transfer speed of the wafer W can be increased gradually or in intervals.

On the other hand, the fluid supplied from above the wafer W may pass through the wafer W and be discharged from a position below the wafer W. At this time, the fluid may be supplied at least before the wafer W is moved to a position above the first set position P1, and may also be supplied to the wafer W during the process of moving to the second set position P2 as needed.

At this time, the fluid is discharged in combination with the residual charge remaining between the wafer W and the chuck 20 , so that the residual charge can be completely discharged.

For example, the fluid may be an inert gas or a gas close to an inert gas. Specifically, the fluid may be formed of argon (Ar) series or dinitrogen (N ₂ ) series.

On the other hand, when the transfer speed of the wafer W is changed, at least one of the volume and the pressure of the fluid supplied to the inside of the chamber 10 may be changed. For example, the capacity of the fluid may vary from 50 seem to 500 seem. In addition, the pressure of the fluid can be changed within the range of 5mT to 1000mT.

Specifically, when the transfer speed of the wafer W increases, at least one of the volume and the pressure of the fluid may decrease in size. For example, compared with the volume of fluid during the process of the wafer W being spaced apart from the chuck 20 and being moved to the first set position P1 or the process of the wafer W being moved from the first set position P1 to the third set position P3 and pressure, at least one of volume and pressure of the fluid during the wafer W being transferred from the third set position P3 to the second set position P2 may be smaller.

Thereby, as the transfer speed of the wafer W increases, at least one of the volume and the pressure of the fluid can be reduced, so that the wafer W can be transferred stably.

Although the present invention has been described in detail through preferred embodiments above, the present invention is not limited thereto, but can be variously implemented within the scope of the patent application.

100: wafer processing device 10: chamber 20: chuck 30: lift pin W: wafer FP: flow path d ₁ : first distance d ₂ : second distance P1: first set position P2: second set position P3: The third setting position S110, S120, S130, S210, S220, S230, S240: steps

FIG. 1 is a schematic diagram illustrating a release process of a wafer according to an embodiment of the present invention. FIG. 2 is a flowchart illustrating a wafer release method according to an embodiment of the present invention. FIG. 3 is a schematic diagram illustrating a process of changing the speed of a wafer release process according to an embodiment of the present invention. FIG. 4 is a schematic diagram showing a releasing process of a wafer according to another embodiment of the present invention. FIG. 5 is a flowchart illustrating a wafer release method according to another embodiment of the present invention.

S110, S120, S130: steps

Claims (15)

A wafer releasing method, comprising: the step of reversing the polarity of a voltage applied to a chuck; a first transfer step of raising a lift pin received in the chuck from the chuck at a first transfer speed to transfer a wafer supported on the chuck to a first set position; and causing the lift pin to rise at a second transfer speed different from the first transfer speed to transfer the wafer disposed at the first set position to a second second set position higher than the first set position. Transfer steps. Wafer release method as described in Claim 1, wherein, The second set position is a position where the wafer is transferred. Wafer release method as described in Claim 1, wherein, The first transfer speed is slower than the second transfer speed. Wafer releasing method as described in claim 3, wherein, The relative ratio of the first transfer speed to the second transfer speed is 1:2 to 1:5. Wafer release method as described in Claim 1, wherein, The distance from the chuck to the first set position is shorter than the distance from the chuck to the second set position. Wafer releasing method as described in claim item 5, wherein, A relative ratio of a first distance from the chuck to the first setting position to a second distance from the chuck to the second setting position is 1:4 to 1:6. Wafer release method as described in Claim 1, wherein, The wafer is continuously moved from the first set position to the second set position. A wafer releasing method, comprising: the step of reversing the polarity of a voltage applied to a chuck; a first transfer step of raising a lift pin accommodated in the chuck from the chuck at a first transfer speed to transfer a wafer supported on the chuck to a first set position; a third transfer step of lowering the lift pin at a third transfer speed to transfer the wafer disposed at the first set position to a third set position lower than the first set position; and raising the lift pin at a second transfer speed different from the first transfer speed and the third transfer speed to transfer the wafer disposed at the third set position to a first set position higher than the first set position 2. The second transfer step of setting the position. Wafer releasing method as described in Claim 8, wherein, The third transfer speed is the same speed as the first transfer speed or faster than the first transfer speed. Wafer releasing method as described in Claim 9, wherein, The relative ratio of the first transfer speed to the second transfer speed is 1:2 to 1:5, The relative ratio of the third transfer speed to the second transfer speed is 1:2 to 1:5. Wafer releasing method as described in Claim 8, wherein, The third set position is the position where the wafer is supported on the chuck. Wafer releasing method as described in Claim 8, wherein, A flow path is formed between the chuck and the wafer when the wafer supported by the chuck is moved to the first set position, When the wafer arranged at the first set position is moved to the third set position, when the fluid supplied from the upper part of the wafer and discharged from the lower position than the wafer passes through the flow path The upper surface of the chuck is in contact with the lower surface of the wafer. Wafer releasing method as described in Claim 8, wherein, At least one of the first transfer step and the second transfer step includes a plurality of intervals in which the speed can be increased progressively or in intervals. Wafer release method as described in any one of claim 8 to claim 12, wherein, At least before the wafer is moved to a position above the first set position, the fluid supplied from above the wafer passes through the wafer and is discharged from a position below the wafer. Wafer releasing method as described in claim 14, wherein, When the transfer speed of the wafer is changed, at least one of the volume and the pressure of the fluid is changed.

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