Wafer cleaning method

Abstract

The present application provides a semiconductor material post-polishing cleaning process monitoring method. Since the cleaning element contacts the surface of the semiconductor material and removes particles by wiping the surface of the semiconductor material, the strength of the cleaning force is determined by the contact pressure of the cleaning element and the semiconductor material. The greater the contact pressure of the cleaning element and the semiconductor material, the greater the dynamic friction between the cleaning element and the semiconductor material (dynamic friction is proportional to the positive pressure). The dynamic friction between the cleaning element and the semiconductor material will be reflected in the torque of the motor rotating the cleaning element, so as long as the torque is monitored, the contact state of the cleaning element and the semiconductor material can be obtained. Since the torque of the motor is proportional to the current flowing through the stator (or rotor) coil of the motor, the torque of the motor and thus the contact state between the cleaning element and the semiconductor material can be obtained by measuring the current driving the motor.

Description

Technical Field

[0001] This application relates to the technical field of semiconductor material grinding processes, and in particular to a wafer cleaning method. Background Technology

[0002] In the Taiko backside grounding process, the ground wafer needs to have its resist surface cleaned before being removed from the machine to reduce the impact of silicon particles remaining on the wafer surface. The wafer resist surface cleaning process involves contacting the ground wafer resist surface with a sponge brush, which rotates and wipes the resist surface to remove silicon particles.

[0003] When the machine detects a high concentration of silicon particles on the wafer's adhesive film surface, the operator, based on experience and the machine's parameter range, increases the wafer's downward movement distance. This indirectly increases the contact pressure between the wafer's adhesive film surface and the sponge, enhancing cleaning power. Whenever insufficient cleaning power is encountered, and replacing the sponge fails to improve the situation, the operator, based on experience and intuition, increases the downward pressure on the wafer, further increasing the contact pressure between the sponge and the wafer, thus improving cleaning power. However, because this method cannot detect the magnitude of the pressure between the wafer and the sponge after grounding, it often easily crushes wafers with a relatively thin profile. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this application is to provide a wafer cleaning method to solve the problem that the prior art cannot detect the pressure between the semiconductor material and the cleaning process, which easily causes damage to the semiconductor material.

[0005] To achieve the above and other related objectives, this application provides a wafer cleaning method. The semiconductor cleaning equipment performs a cleaning process on the wafer after grinding. The semiconductor cleaning equipment includes a moving mechanism, a mounting bracket disposed on the moving mechanism, a rotating stage disposed opposite to the mounting bracket, a cleaning component disposed on the rotating stage, and a motor driving the rotating stage to rotate. The wafer is disposed on the mounting bracket, and the cleaning component contacts the wafer to perform cleaning. The method includes:

[0006] The motor drives the rotary table to rotate, and the moving mechanism moves the mounting bracket to the starting position;

[0007] The first current data I1 is obtained by measuring the drive current of the motor;

[0008] The moving mechanism moves the mounting bracket from the starting position to the rotary table and measures the drive current of the motor to obtain the second current data I2;

[0009] Compare the first current data I1 and the second current data I2. If the difference between the first current data I1 and the second current data I2 divided by the first current data I1 is greater than the first difference δ1, then it is determined that the semiconductor material has reached the contact position with the cleaning component.

[0010] The moving mechanism causes the mounting bracket to continue moving from the contact position to the rotary table a predetermined distance d, so that the semiconductor material reaches the optimal cleaning position;

[0011] The semiconductor material undergoes the cleaning process at the optimal cleaning location for a period of time.

[0012] Optionally, it also includes:

[0013] The third current data I3 is obtained by measuring the drive current of the motor during a monitoring period within the working time.

[0014] The fourth current data I4 is obtained by measuring the drive current of the motor after the said working time;

[0015] Comparing the third current data I3 with the fourth current data I4, if the difference between the third current data I3 and the fourth current data I4 divided by the third current data I3 is greater than the second difference δ2 within a certain period of time, then it is determined that there is an abnormality in the cleaning process.

[0016] Optionally, the second difference is greater than -100% and less than 25%.

[0017] Optionally, the first difference is greater than 3% and less than 6%.

[0018] Optionally, if the difference between the first current data I1 and the second current data I2 divided by the first current data I1 is less than or equal to the first difference δ1, and the distance the mounting bracket moves from the starting position to the rotary table is greater than the critical distance value c, then the cleaning process is terminated.

[0019] Optionally, the travel distance from the starting position to the rotary table is defined, and the critical distance value is equal to half of the travel distance.

[0020] Optionally, the working time is greater than 2 seconds and less than 5 seconds.

[0021] Optionally, the method further includes: the mounting bracket moving from the starting position to the rotary table at a first speed to a current value comparison position, starting to compare the first current data I1 and the second current data I2 at the current value comparison position, and the mounting bracket moving from the current value comparison position to the rotary table at a second speed, wherein the second speed is less than the first speed.

[0022] Optionally, the motor is electrically connected to the drive module, and the drive module obtains the first current data I1, the second current data I2, the third current data I3 and the fourth current data I4 and transmits them to the controller.

[0023] Optionally, the controller transmits the first current data I1, the second current data I2, the third current data I3, and the fourth current data I4 to the user interface.

[0024] As described above, the method for monitoring the cleaning process after grinding semiconductor materials in this application has the following beneficial effects:

[0025] Since the cleaning component contacts the surface of the semiconductor material and removes particles by wiping the surface, the cleaning force is determined by the contact pressure between the cleaning component and the semiconductor material. The greater the contact pressure, the greater the dynamic friction between them (dynamic friction is proportional to the forward pressure). This dynamic friction is reflected in the torque of the motor that rotates the cleaning component; therefore, monitoring the torque allows us to determine the contact state between the component and the semiconductor material. Because the motor torque is proportional to the current flowing through the stator (or rotor) coils, measuring the current drives the motor allows us to determine the torque and thus the contact state between the component and the semiconductor material. By monitoring the motor current, we can move the cleaning component to the optimal position for contact with the semiconductor material during the cleaning process, and detect any abnormalities to prevent damage to the semiconductor material. Attached Figure Description

[0026] Figure 1 The diagram shows a system configuration for implementing the semiconductor material grinding and cleaning process monitoring method of this application.

[0027] Figure 2 This is a top view showing the arrangement of semiconductor materials and cleaning components during the cleaning process following semiconductor material grinding.

[0028] Figure 3 The graph shows the relationship between the motor's torque and current.

[0029] Figure 4 The graph shows the relationship between the motor torque and the contact pressure between the cleaning component and the semiconductor material.

[0030] Figure 5 The graph shows the relationship between the motor current and the contact pressure between the cleaning component and the semiconductor material.

[0031] Figure 6 The flowchart shown is a method for monitoring the cleaning process after grinding semiconductor materials according to an embodiment of this application.

[0032] Component labeling explanation

[0033] 1: Semiconductor material grinding and cleaning device; 1A: Moving component; 1B: Cleaning component; 1C: Control component; 10: Moving mechanism; 11: Track; 12: Slider; 20: Mounting bracket; 30: Rotary table; 40: Cleaning component; 50: Motor; 51: Output shaft; 60: Servo driver; 70: Programmable logic controller; 80: Industrial control calculator; 90: Monitor; B: Belt; F: Adhesive film; W: Semiconductor material. Detailed Implementation

[0034] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. This application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application.

[0035] For ease of description, spatial relation terms such as “below,” “under,” “lower than,” “below,” “above,” and “upper” may be used herein to describe the relationship between one component or feature shown in the accompanying drawings and other components or features. It will be understood that these spatial relation terms are intended to include directions other than those depicted in the accompanying drawings for devices in use or operation.

[0036] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0037] Figure 1 The diagram shown is a structural schematic of a semiconductor cleaning device for implementing this application. Figure 1 As shown, the semiconductor cleaning equipment 1 of this application includes a moving component 1A, which includes a moving mechanism 10 and a mounting bracket 20 disposed on the moving mechanism 10. The wafer W is disposed on the mounting bracket 20. The moving mechanism 10 has a track 11 and a slider 12. The mounting bracket 20 is connected to the slider 12. As the slider 12 moves up and down along the track 11, the mounting bracket 20 also moves up and down along the track 11, causing the semiconductor material W to approach or move away from the rotary table 30.

[0038] like Figure 1 As shown, the semiconductor cleaning equipment of this application also includes a cleaning component 1B, which includes a rotary table 30 disposed opposite to the mounting bracket 20, a cleaning element 40 disposed on the rotary table 30, and a motor 50 for driving the rotary table 30 to rotate. The rotary table 30 is connected to the output shaft 51 of the motor 50 via a belt B. The rotation of the output shaft 51 of the motor 50 drives the rotary table 30 to rotate, thereby causing the cleaning element 40 disposed on the rotary table 30 to rotate. When the semiconductor material W moves and approaches the rotary table 30, the cleaning element 40 contacts the adhesive film F of the semiconductor material W and moves relative to the adhesive film F to wipe and clean it. In this embodiment, the semiconductor material W is a wafer, and the surface of the semiconductor material W has an adhesive film F. In this embodiment, the cleaning element 40 is a sponge brush. The semiconductor material post-grinding cleaning process of this application is a cleaning process of the adhesive film F of the semiconductor material W performed after the back-side thinning process to remove silicon particles attached to the surface of the adhesive film F of the semiconductor material W.

[0039] like Figure 1 As shown, the semiconductor cleaning equipment of this application also includes a control component 1C, which includes a servo driver 60, a programmable logic controller (PLC) 70, and an industrial control calculator 80. The motor 50 is electrically connected to the servo driver 60, the servo driver 60 is electrically connected to the PLC 70, and the PLC 70 is connected to the industrial control calculator 80. An operating interface program is installed in the industrial control calculator 80, allowing the operator to monitor and operate the equipment via a touchscreen on a monitor 90.

[0040] Since the cleaning force of the cleaning component 40 on the semiconductor material W is directly proportional to the pressure of the cleaning component 40 in contact with the semiconductor material W, too low a contact pressure indicates insufficient cleaning force, while too high a contact pressure may cause the thinned semiconductor material W to break and be damaged. Therefore, the monitoring method for the cleaning process after semiconductor material grinding in this embodiment is used to monitor the contact pressure between the semiconductor material W and the cleaning component 40 to determine and adjust the cleaning force of the cleaning component 40 on the semiconductor material W. Because the dynamic friction force of the cleaning component 40 relative to the semiconductor material W in moving contact is directly proportional to the contact pressure between the semiconductor material W and the cleaning component 40, and the increase or decrease of the dynamic friction force of the cleaning component 40 relative to the semiconductor material W in moving contact will be reflected in the change of torque of the motor 50 driving the rotary table 30 to rotate. The torque calculation formula of the motor 50 is as follows:

[0041] T = KΦI, where T (unit N·m) represents the torque of the motor (the resistance during rotation, which is also the primary data reflecting the contact pressure between the sponge brush and the wafer); K represents the proportional constant, which is 1 for a DC servo motor; Φ (unit Wb) represents the magnetic flux, which is an inherent property parameter in the design and manufacturing of the motor; and I (unit A) represents the drive current, which is the current of the servo driver that drives the motor.

[0042] The change in motor torque is proportional to the current flowing through the stator (or rotor) coil of motor 50. Therefore, by acquiring and analyzing the drive current of the servo driver 60 of motor 50, the magnitude of the resistance currently experienced by motor 50 can be reflected, thereby reflecting the contact pressure between the cleaning component 40 and the semiconductor material W, achieving the purpose of real-time monitoring and dynamic adjustment.

[0043] Please see Figure 3 , Figure 4 and Figure 5 These are, respectively, the relationship between the motor's torque and current, the relationship between the motor's torque and the contact pressure between the cleaning component and the semiconductor material, and the relationship between the motor's current and the contact pressure between the cleaning component and the semiconductor material.

[0044] from Figure 3 The curve shown is represented by the equation T = m·K·I + b, where m is an inherent parameter of the motor, typically taken as 1. Figure 3 The data at each point on the curve yields T = 0.08I.

[0045] from Figure 4 The curve shown is represented by the equation P = K·T + b, where P is the contact pressure between the semiconductor material W and the cleaning component 40. Figure 4 The data at each point on the curve yields P = 50T⁻⁴, and the data at each point are as follows: Figure 5 As shown.

[0046] From the above two equations, we can obtain the relationship between the contact pressure and the current of the motor 50: P = 4I-4. Therefore, by obtaining and analyzing the drive current of the servo driver 60 of the motor 50, we can obtain the current contact pressure between the cleaning component 40 and the semiconductor material W, which can be used to determine the cleaning force of the cleaning component 40 on the semiconductor material W.

[0047] Please see Figure 6 This is a flowchart illustrating a method for monitoring the cleaning process after grinding semiconductor materials, according to an embodiment of this application. Please also refer to... Figure 1 and Figure 2 In step S1, motor 50 drives rotary table 30 to rotate, and moving mechanism 10 moves mounting bracket 20 to the starting position. The starting position is a predetermined distance D from rotary table 30. Then, step S2 is performed.

[0048] In step S2, the drive current of motor 50 is measured to obtain the first current data I1. Then, proceed to step S3.

[0049] In step S3, the mounting bracket 20 moves from the starting position to the rotary table at a first speed to the current comparison position. From the current comparison position, the drive current of the motor 50 is continuously measured to obtain the second current data I2. Then, the process proceeds to step S4.

[0050] In step S4, the mounting bracket 20 moves from the current value comparison position toward the rotary table 30 at a second speed, which is less than the first speed. Then, proceed to step S5.

[0051] In step S5, the first current data I1 and the second current data I2 are compared, and it is determined whether (I2-I1) / I1 is greater than a first difference δ1. In this embodiment, the range of the first difference δ1 is 3% < δ1 < 6%. If (I2-I1) / I1 is greater than the first difference δ1, it indicates that the cleaning component 40 is in contact with the semiconductor material W, and the process proceeds to step S6; otherwise, it indicates that the cleaning component 40 has not yet been in contact with the semiconductor material W, and the process proceeds to step S51.

[0052] The mounting bracket 20 moves from the starting position to the current comparison position at a relatively high first speed. The current comparison position is where the cleaning component 40 is relatively close to but has not yet come into contact with the semiconductor material W. Generally, it is located at a distance of 5 mm from the cleaning component 40, which can shorten the time. Then, the mounting bracket 20 moves from the current comparison position to the rotary table 30 at a relatively low second speed, and compares the first current data I1 and the second current data I2 to determine whether the cleaning component 40 has come into contact with the semiconductor material W. The second speed is generally set between 0.5 mm / s and 2.0 mm / s.

[0053] In step S51, the distance the mounting bracket 20 has moved is obtained by detecting the rotation speed of the motor 50 using an encoder. This moving distance is then compared to a critical distance value c. If the moving distance is less than the critical distance value c, the process proceeds to step S511; otherwise, it proceeds to step S512. The critical distance value c represents the critical value at which the semiconductor material W on the mounting bracket 20 collides with the rotary table 30. In this embodiment, the critical distance value c is half the distance D from the starting position to the rotary table 30, i.e., c = D / 2.

[0054] In step S511, since the semiconductor material W does not collide with the rotary table 30, the mounting bracket 20 continues to move toward the rotary table 30 at the second speed.

[0055] In step S512, since the semiconductor material W may collide with the rotary table 30, a warning is issued, and the rotary table 30 is subsequently stopped and the cleaning process is terminated.

[0056] In step S6, it is determined that the semiconductor material W has reached the contact position with the cleaning component 40. Then, proceed to step S7.

[0057] In step S7, the distance the mounting bracket 20 has moved is obtained by detecting the rotation speed of the motor 50 using an encoder, thereby obtaining the distance value of the contact position. Then, proceed to step S8.

[0058] In step S8, based on the operator's experience, it is known that the optimal cleaning force can be obtained by moving the semiconductor material W a predetermined distance d after it comes into contact with the cleaning component 40. Therefore, the mounting bracket 20 is moved a predetermined distance d from the contact position toward the rotary table 30 so that the semiconductor material W reaches the optimal cleaning position. Then, steps S9 and S91 are performed.

[0059] In step S9, the semiconductor material W undergoes a cleaning process at the optimal cleaning position for a certain working time. In this embodiment, the working time is in the range of 2 to 5 seconds, for example, 3 seconds. Then, proceed to step S10.

[0060] In step S91, the drive current of motor 50 is measured during a monitoring period within the working time to obtain the third current data I3. The monitoring period is shorter than the working time, and the third current data I3 measured within the monitoring period is averaged over time to be used as the average current value within the working time.

[0061] In step S10, the drive current of motor 50 is measured after the operating time to obtain the fourth current data I4. Then, proceed to step S11.

[0062] In step S11, the third current data I3 and the fourth current data I4 are compared. Within a certain time interval, is (I4-I3) / I3 greater than the second difference δ2? In this embodiment, the range of the second difference δ2 is -100% < second difference δ2 < 25%. If (I4-I3) / I3 is greater than the second difference δ2, then proceed to step S12; otherwise, proceed to step S13.

[0063] In step S12, an abnormality is determined in the cleaning process, and an alert is issued.

[0064] In step S13, it is determined that the cleaning process is proceeding normally and that the cleaning process is completed.

[0065] The servo driver 60 acquires first current data I1, second current data I2, third current data I3, and fourth current data I4 and transmits them to the programmable logic controller 70. The servo driver 60 then transmits the first current data I1, second current data I2, third current data I3, and fourth current data I4 to the user interface.

[0066] Since the cleaning component contacts the surface of the semiconductor material and removes particles by wiping the surface, the cleaning force is determined by the contact pressure between the cleaning component and the semiconductor material. The greater the contact pressure, the greater the dynamic friction between them (dynamic friction is proportional to the forward pressure). This dynamic friction is reflected in the torque of the motor that rotates the cleaning component; therefore, monitoring the torque allows us to determine the contact state between the component and the semiconductor material. Because the motor torque is proportional to the current flowing through the stator (or rotor) coils, measuring the current drives the motor allows us to determine the torque and thus the contact state between the component and the semiconductor material. By monitoring the motor current, we can move the cleaning component to the optimal position for contact with the semiconductor material during the cleaning process, and detect any abnormalities to prevent damage to the semiconductor material.

[0067] The above embodiments are merely illustrative of the principles and effects of this application and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. A wafer cleaning method, applied to a semiconductor cleaning equipment, wherein the semiconductor cleaning equipment performs a cleaning process on a wafer after grinding, the semiconductor cleaning equipment comprising a moving mechanism, a mounting bracket disposed on the moving mechanism, a rotating stage disposed opposite to the mounting bracket, a cleaning component disposed on the rotating stage, and a motor for driving the rotating stage to rotate, the wafer being disposed on the mounting bracket, and the cleaning component contacting the wafer to perform cleaning, characterized in that... ,include: The motor drives the rotary table to rotate, and the moving mechanism drives the mounting bracket to move to the starting position, with a predetermined distance D between the starting position and the rotary table; The first current data I1 is obtained by measuring the drive current of the motor; The moving mechanism drives the mounting bracket to move from the starting position to the rotary table, and monitors the drive current of the motor to obtain the second current data I2; The mounting bracket moves from the starting position to the rotary table at a first speed to the current value comparison position. At the current value comparison position, the first current data I1 and the second current data I2 are compared. The mounting bracket moves from the current value comparison position to the rotary table at a second speed, which is less than the first speed. Compare the first current data I1 and the second current data I2. If the difference between the first current data I1 and the second current data I2 divided by the first current data I1 is greater than the first difference value δ1, then it is determined that the wafer has reached the contact position with the cleaning component. If the difference between the first current data I1 and the second current data I2 divided by the first current data I1 is less than or equal to the first difference value δ1, and the distance that the mounting bracket moves from the starting position to the rotary table is greater than the critical distance value c, then the cleaning process is stopped. The moving mechanism causes the mounting bracket to continue moving a predetermined distance d from the contact position toward the rotary table so that the wafer reaches the optimal cleaning position; The wafer undergoes the cleaning process at the optimal cleaning location during the working time.

2. The wafer cleaning method as described in claim 1, characterized in that... It also includes: The drive current of the motor is measured during a monitoring period within the working time to obtain a third current data I3; the drive current of the motor is measured after the working time is implemented to obtain a fourth current data I4; Comparing the third current data I3 with the fourth current data I4, if the difference between the third current data I3 and the fourth current data I4 divided by the third current data I3 is greater than the second difference δ2 within a certain period of time, then it is determined that there is an abnormality in the cleaning process.

3. The wafer cleaning method as described in claim 2, characterized in that... The second difference is greater than -100% and less than 25%.

4. The wafer cleaning method as described in claim 1, characterized in that... The first difference is greater than 3% and less than 6%.

5. The wafer cleaning method as described in claim 1, characterized in that... Define the travel distance from the starting position to the rotary table, where the critical distance value is equal to half of the travel distance.

6. The wafer cleaning method as described in claim 1, characterized in that... The working time is greater than 2 seconds and less than 5 seconds.

7. The wafer cleaning method as described in claim 2, characterized in that... The motor is electrically connected to the drive module, and the drive module obtains the first current data I1, the second current data I2, the third current data I3 and the fourth current data I4 and transmits them to the controller.

8. The wafer cleaning method as described in claim 7, characterized in that... The driving module transmits the first current data I1, the second current data I2, the third current data I3, and the fourth current data I4 to the user interface.

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