TWI568533B - Method of monitoring polishing process and polishing system thereof - Google Patents

Description

Method for monitoring grinding process and grinding system thereof

This invention relates to a method of monitoring a grinding process and a grinding system therefor.

As the industry advances, flattening processes are often adopted as processes for producing various components. In the flattening process, the chemical mechanical polishing process is often used by the industry. In general, a chemical mechanical polishing (CMP) process is to attach a polishing pad to a polishing stage, and supply a polishing slurry having a mixture of chemicals and abrasive powders to the polishing pad, such as a semiconductor wafer. Applying a pressure to press it onto the polishing pad, and causing the abrasive article and the polishing pad to move relative to each other, and trimming the surface of the polishing pad with a dresser such as a diamond disk. By the mechanical friction generated by the relative motion and the chemical action of the abrasive slurry, the surface layer of the partially polished object is removed, and the surface thereof is gradually flattened to achieve the purpose of planarization. In the grinding process, there may be abnormalities in the surface of the polishing pad that are partially uneven, such as uneven accumulation of abrasive powder on the surface of the polishing pad, drilling of the diamond disk. The stone particles fall on the surface of the polishing pad, or the polishing pad causes local degumming and bulging under the action of long-term stress, so that the pressure of the abrasive object is abnormally controlled, causing the abrasive object to be fragmented and scrapped, and the grinding machine must be shut down. Check, thus increasing manufacturing costs.

The invention provides a method for monitoring a grinding process and a grinding system thereof, which can avoid the phenomenon of fragmentation caused by an abnormality of pressure control in the grinding process during the grinding process.

The method for monitoring a polishing process of the present invention comprises sequentially grinding a plurality of abrasive articles using a polishing head and a polishing pad. Collect individual pressure signal values of the ground abrasive article during the grinding process. The mobile reference is calculated using the pressure signal value. Use the mobile reference and set a monitoring range as a monitoring standard for successive abrasive objects to monitor the grinding process.

The invention further provides a grinding system for performing a grinding process on the abrasive article. The grinding system includes a polishing pad, a polishing head, a pressure sensing device, and a controller. The polishing head is disposed on the polishing pad, and the abrasive article is mounted in the polishing head. The pressure sensing device is disposed on the polishing head, wherein the pressure sensing device collects individual pressure signal values of the abrasive article during the grinding process. The controller collects the pressure signal value measured by the pressure sensing device to calculate the movement reference and set a monitoring range, and monitors the grinding process as a monitoring standard of the successive abrasive objects.

Based on the above, the method of monitoring the grinding process and the grinding system of the present invention The pressure sensing device collects the individual pressure signal values of the abrasive article in the grinding process, and the controller uses the controller to calculate the monitoring standard according to the pressure signal value of each abrasive object, thereby monitoring the standard to detect whether the polishing pad has an abnormal state. Therefore, the user can monitor the change of the control pressure of the abrasive object in time, and terminate the grinding process when the pressure control is abnormal, thereby avoiding the occurrence of fragmentation, thereby effectively reducing the manufacturing cost.

The above described features and advantages of the invention will be apparent from the following description.

100‧‧‧ grinding system

102‧‧‧Loading station

104‧‧‧ polishing pad

110‧‧‧ polishing head

112‧‧‧ Pressure sensing device

114‧‧‧ Controller

116‧‧‧Airbag

116a‧‧‧First pressure zone

116b‧‧‧Second pressure zone

120‧‧‧Abrased objects

A‧‧‧Rotation direction A

B‧‧‧Rotation direction B

C‧‧‧Moving direction C

M‧‧‧Monitoring standards

M1, M2‧‧‧ curve

P‧‧‧ fold line

Pressure signal values of P1, P2, P3‧‧‧ grinding objects

1A is a schematic cross-sectional view of a polishing system in accordance with an embodiment of the present invention.

1B is a top plan view of an air bag of a polishing head in accordance with an embodiment of the present invention.

2 is a flow chart showing a method of monitoring a polishing process in accordance with an embodiment of the present invention.

3 is a schematic diagram showing the relationship between pressure signal values and time of an individual abrasive article in a polishing process in accordance with an embodiment of the present invention.

1A is a schematic cross-sectional view of a polishing system in accordance with an embodiment of the present invention. 1B is a top plan view of an air bag of a polishing head in accordance with an embodiment of the present invention. 2 is a flow chart showing a method of monitoring a polishing process in accordance with an embodiment of the present invention. Referring first to FIG. 1 , the polishing system 100 includes a carrier 102 , a polishing pad 104 , a polishing head 110 , a pressure sensing device 112 , a controller 114 , and a polishing article 120 . The carrier 102 is used, for example, to carry a polishing pad 104. The polishing pad 104 is attached to the surface of the carrier 102, for example, to polish the abrasive article 120. The polishing pad 104 is composed of, for example, a polymer substrate, and the polymer substrate may be a polymer substrate synthesized by a thermosetting resin or a thermoplastic resin. The material of the polishing pad 104 is not particularly limited in the present invention. .

The polishing head 110 is disposed on the polishing pad 104, thereby holding the abrasive article 120 on the polishing head 110. As shown in FIG. 1, the polishing head 110 has an air bag 116, and the abrasive article 120 is attached to the outer surface of the air bag 116. The polishing head 110 can control the internal air pressure of the airbag 116 by inputting gas to the airbag 116 to apply pressure to the abrasive article 120, thereby pressing the abrasive article 120 against the surface of the polishing pad 104 to make the surface to be polished of the abrasive article 120. It is in contact with the polishing pad 104.

As shown in Figures 1A and 1B, the bladder 116 in the abrading head 110 has two separate first pressure zones 116a and a second pressure zone 116b. Wherein, during the polishing process, the polishing system 100 can input different amounts of gas to the first pressure zone 116a and the second pressure zone 116b, respectively, so that the abrasive article 120 is different in the first pressure zone 116a and the second pressure zone 116b. pressure. However, the present invention is not limited thereto. In other embodiments, the airbag 116 may have a single air pressure zone, and the airbag 116 may also have two or more pressure zones of different pressures, for example, three, five, or Seven different pressure zones.

Referring to FIG. 2, step S1 is performed to start the polishing system 100, and sequentially grind the plurality of abrasive objects 120. In an embodiment, when the carrier 102 rotates in a fixed rotational direction, the substrate 102 is simultaneously attached to the surface of the carrier 102. The pad 104 is polished such that the polishing pad 104 can follow the same rotational direction as the carrier 102. The polishing head 110 rotates in the same rotational direction, and simultaneously drives the abrasive article 120 attached to the outer surface of the airbag 116, so that the abrasive article 120 rotates in the same rotational direction as the polishing head 110. In this embodiment, the rotation direction of the loading table 102 is, for example, the rotation direction A and the rotation direction of the polishing head 110 is, for example, the rotation direction B, wherein the rotation direction A has a rotation direction the same as the rotation direction B, so that the polishing pad 104 is relatively moved with the polishing head 110, but the present invention is not limited thereto, and the rotation direction A and the rotation direction B may be selected to be opposite directions. In an embodiment, when the polishing head 110 is oscillated back and forth along the moving direction C, the abrasive article 120 attached to the outer surface of the airbag 116 is simultaneously driven, so that the abrasive article 120 can swing back and forth according to the moving direction C. Grinding process. In one embodiment, in addition to rotating the abrasive article 120 on the polishing pad 104, the polishing head 110 can simultaneously oscillate the abrasive article 120 on the polishing pad 104 to cause the abrasive article 120 and the polishing pad 104 to be rotated. The contact between the two is not limited to a specific area, which helps to make the grinding rate and uniformity more stable and to make the grinding process more uniform.

Next, step S2 is performed to collect the individual pressure signal values of the ground abrasive article 120 during the polishing process. The pressure sensing device 112 is disposed inside the polishing head 110, wherein the pressure sensing device 112 collects individual pressure signal values of the abrasive article 120 during the polishing process. In the present embodiment, the polishing head 110 controls the internal air pressure of the airbag 116 by inputting gas to the airbag 116 to apply pressure to the abrasive article 120, and presses the abrasive article 120 against the surface of the polishing pad 104, and the polishing pad 104. Contact. Therefore, the pressure sensing device 112 can detect the pressure inside the air bag 116. The pressure signal value of the abrasive article 120 is measured. The pressure signal value of the ground abrasive article 120 is, for example, a maximum pressure value (maximum), a minimum pressure value, an average pressure value, or a difference between the maximum pressure and the minimum pressure selected from the inside of the air bag 116. . The pressure sensing device 112 and the controller 114 shown in FIG. 1A are located in the polishing head 110. However, the present invention is not limited thereto, and the pressure sensing device 112 and the controller 114 may also be located outside the polishing head 110.

Step S3 is performed to calculate a moving reference using the pressure signal value; and step S4 is performed to calculate a monitoring criterion as a continuous abrasive object by using a moving reference and setting a monitoring range. The controller 114 can collect the pressure signal value of the ground object 120 that has been ground by the pressure sensing device 112 to calculate a movement reference and set a monitoring range. Thereafter, the controller 114 calculates a monitoring standard M as a continuous abrasive article based on the movement reference and the monitoring range to monitor the grinding process. Among them, the monitoring standard M is, for example, a mobile reference addition and subtraction (+/-) monitoring range.

In one embodiment, the movement reference is a moving average selected from the measured pressure signal values of the ground abrasive article 120, a moving median, or a moving mode. ). In another embodiment, the movement reference is, for example, a simple moving average of the pressure signal values of the first n ground abrasive objects 120, and is calculated according to the following formula: B _i = (P _i-1 +... +P _in )/n, where B _i represents the movement reference of the successive abrasive article, and P _in represents the pressure signal value of the nth abrasive object 120 before the successive abrasive article, and n ≧ 2 . In an embodiment, the monitoring range is set, for example, between 50% and 80% of the mobile reference. In another embodiment, the monitored range is, for example, a multiple of the standard deviation of the pressure signal values of the first m ground abrasive articles 120 (eg, 3 times the standard deviation), and m≧3.

Next, step S5 is performed to determine whether the pressure signal value exceeds the monitoring standard M by using the monitoring standard M. When the grinding process is performed, if the pressure sensing device 112 detects that the pressure signal value of the successive abrasive object does not exceed the monitoring standard M calculated by the controller 114 via the internal pressure change of the air bag 116, no abnormal message is generated. The grinding system 100 continues the grinding process. On the other hand, when the pressure sensing device 112 detects that the pressure signal value of the successive abrasive object exceeds the monitoring standard M calculated by the controller 114 via the internal pressure change of the air bag 116, an abnormal message is generated. .

In an embodiment, the factor of the abnormality message is, for example, an abnormal state in which a local unevenness is generated on the surface of the polishing pad 110. During the grinding process, as the abrasive article 120 moves over the surface of the polishing pad 110 that is uneven, the abrasive article 120 undergoes additional pressure changes that indirectly cause the bladder 116 to undergo a pressure change. At this time, the grinding system 100 can offset the pressure change by adjusting the internal pressure of the air bag 116 to automatically correct the additional pressure change of the abrasive article 120. However, when the internal pressure of the airbag 116 is adjusted to correct the additional pressure change of the abrasive article 120, if the pressure sensing device 112 detects the pressure signal value of the abrasive article 120 via the internal pressure of the airbag 116 exceeds the controller 114. The calculated monitoring standard M, the grinding system 100 will generate an abnormal message. The reason for the local unevenness on the surface of the polishing pad 110 is, for example, uneven accumulation of abrasive powder on the surface of the polishing pad, and diamond particles falling off the diamond disk. The invention is caused by falling on the surface of the polishing pad or by causing local degumming and bulging under the action of long-term stress, but the invention is not limited thereto.

In order to avoid the additional damage of the abrasive article 120 during the grinding process, the abrasive article 120 is broken, and the abnormal message is excluded. In the polishing process, if an abnormality message is generated, step S6 is performed to terminate the polishing process to eliminate the abnormality message. Among them, based on factors of different abnormal messages, the present invention does not limit the means for eliminating the abnormal message. When the abnormality message has been excluded, step S1 is repeated to start the grinding system 100 to perform the grinding process. In an embodiment, if the airbag 116 has two or more air pressure zones, the pressure signal value is preferably selected from the air pressure zone of the outermost ring, because the airbag 116 is partially uneven by the surface of the polishing pad 110. When the influence of the area is relatively, it will relatively pass through the air pressure zone of the outermost ring of the air bag 116, but may not pass through the air pressure zone of the inner ring of the air bag 116. Therefore, the pressure signal value is selected from the air pressure zone of the outermost circle, and the surface unevenness of the surface of the polishing pad 110 can be effectively monitored. However, the present invention is not limited thereto. Under certain specific processing conditions, the airbag 116 may have a better detection sensitivity than the inner ring air pressure region, and the pressure signal value is selected to be detected from the air pressure region of the inner ring.

In order to more clearly illustrate the method and polishing system for monitoring the polishing process of the present invention, an experiment is performed in an embodiment of the present invention to explain the determination of an abnormality message. 3 is a schematic diagram showing the relationship between pressure signal values and time of an individual abrasive article in a polishing process in accordance with an embodiment of the present invention. Referring to FIG. 3, in an embodiment, the monitoring standard M calculated by the controller 114 is defined as an area between the curve M1 and the curve M2, and each point on the polyline P is a pressure sensing device. The pressure signal value of the individual abrasive article 120 is detected by the air bag 116. The pressure signal value in this embodiment is the difference between the maximum pressure and the minimum pressure. As is clear from FIG. 3, the pressure signal values P1, P2, and P3 exceed the monitoring standard M calculated by the controller 114. Therefore, when the three pressure signal values P1, P2, and P3 are measured, the grinding system 100 will respectively generate one. Anomaly message. The monitoring method and the polishing system of the present invention can select the termination of the grinding process when the abnormal information is continuously generated, or the polishing process can be terminated when a single abnormal message is generated.

In one embodiment, the grinding system 100 can be applied to a grinding machine that utilizes a polishing head controlled by a closed loop system. The monitoring polishing process and polishing system of the present invention can be applied to a polishing process used in the fabrication of components such as semiconductors, integrated circuits, MEMS, energy conversion, communication, optics, storage disks, and displays, and these components are fabricated. The article 120 used may include a semiconductor wafer, a group III V wafer, a storage element carrier, a ceramic substrate, a polymer substrate, a glass substrate, etc., but is not intended to limit the scope of the invention.

In summary, the method for monitoring the polishing process and the polishing system of the present invention collect the individual pressure signal values of the abrasive article in the grinding process by the pressure sensing device, and use the controller to calculate the monitoring standard according to the pressure signal value of each abrasive article. This monitoring standard detects whether the abrasive object has a state of abnormal pressure control, and forms an early warning mechanism to avoid the occurrence of fragmentation, thereby effectively reducing manufacturing costs.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and any one of ordinary skill in the art can make some changes and refinements without departing from the spirit and scope of the present invention. The scope of protection of the present invention It is subject to the definition of the scope of the patent application attached.

100‧‧‧ grinding system

102‧‧‧Loading station

104‧‧‧ polishing pad

110‧‧‧ polishing head

112‧‧‧ Pressure sensing device

114‧‧‧ Controller

116‧‧‧Airbag

116a‧‧‧First pressure zone

116b‧‧‧Second pressure zone

120‧‧‧Abrased objects

A‧‧‧Rotation direction A

B‧‧‧Rotation direction B

C‧‧‧Moving direction C

Claims (24)

A method for monitoring a polishing process includes: sequentially performing a grinding process on a plurality of abrasive articles by using a polishing head and a polishing pad; and collecting individual pressure signal values of the polished abrasive articles in the polishing process; The pressure signal values calculate a movement reference; and use the movement reference and set a monitoring range as a monitoring standard for the successive abrasive objects to monitor the polishing process. The method of monitoring a polishing process according to claim 1, wherein the polishing head has an air bag, and the abrasive article is attached to an outer surface of the air bag. The method of monitoring a polishing process as described in claim 2, wherein the pressure signal value is detected from the air bag. The method of monitoring a grinding process according to claim 3, wherein the air bag has two or more air pressure zones, and the pressure signal value is detected from a pressure zone of the outermost ring. The method of monitoring a grinding process according to claim 1, wherein the pressure signal value is selected from a maximum pressure value, a minimum pressure value, an average pressure value, or a difference between the maximum pressure and the minimum pressure. The method of monitoring a polishing process according to claim 1, wherein the moving reference is selected from a moving average, a moving median, or a moving mode. The method for monitoring a polishing process according to claim 1, wherein the moving reference is a simple moving average of pressure signal values of the first n ground abrasive objects, and is calculated according to the following formula: B _i = (P _i-1 +...+P _in )/n where B _i represents the movement reference of the successive abrasive article, and P _in represents the pressure signal value of the nth abrasive article before the successive abrasive article, and n ≧ 2 . The method of monitoring a grinding process according to claim 1, wherein the monitoring range is between 50% and 80% of the moving reference. The method of monitoring a polishing process according to claim 1, wherein the monitoring range is a multiple of a standard deviation of pressure signal values of the first m ground abrasive objects, and m≧3. The method of monitoring a grinding process according to claim 1, wherein the monitoring standard is the movement reference +/- the monitoring range. The method of monitoring a polishing process according to claim 1, wherein an abnormality message is generated when a pressure signal value when the polishing process is performed exceeds the monitoring standard. The method of monitoring a polishing process according to claim 1, wherein the polishing process is terminated when a pressure signal value when the polishing process is performed exceeds the monitoring standard. A grinding system for sequentially performing a grinding process on a plurality of abrasive articles, the polishing system comprising: a polishing pad; a polishing head disposed on the polishing pad, and each polishing object is mounted on the polishing pad a pressure sensing device, wherein the pressure sensing device collects individual pressure signal values of the ground objects in the grinding process; and a controller that collects the pressure sensing device The pressure signal values are measured to calculate a movement reference and set a monitoring range as a monitoring standard for the successive abrasive objects to monitor the polishing process. The polishing system of claim 13, wherein the polishing head has an air bag, and each of the abrasive articles is attached to an outer surface of the air bag. The polishing system of claim 14, wherein the pressure signal value is detected from the air bag. The grinding system of claim 15, wherein the air bag has two or more air pressure zones, and the pressure signal value is detected from a pressure zone of the outermost ring. The polishing system of claim 13, wherein the pressure signal value is selected from a maximum pressure value, a minimum pressure value, an average pressure value, or a difference between the maximum pressure and the minimum pressure. The grinding system of claim 13, wherein the moving reference is selected from the group consisting of a moving average, a moving median, or a moving mode. The polishing system of claim 13, wherein the movement reference is a simple moving average of the pressure signal values of the first n ground abrasive objects, and is calculated according to the following formula: B _i = (P _{i -1} +...+P _in )/n where B _i represents the movement reference of the successive abrasive article, and P _in represents the pressure signal value of the nth abrasive article before the successive abrasive article, and n ≧ 2 . The grinding system of claim 13, wherein the monitoring range is between 50% and 80% of the movement reference. The polishing system of claim 13, wherein the monitoring range is a multiple of a standard deviation of pressure signal values of the first m ground abrasive objects, and m≧3. The grinding system of claim 13, wherein the monitoring criterion is the movement reference +/- the monitoring range. The polishing system of claim 13, wherein an abnormality message is generated when a pressure signal value when the polishing process is performed exceeds the monitoring standard. The polishing system of claim 13, wherein the polishing process is terminated when a pressure signal value when the polishing process is performed exceeds the monitoring standard.