Method for adjusting distribution of grinding fluid and spraying device of grinding fluid

Abstract

The invention provides a grinding fluid distribution adjusting method and a grinding fluid spraying device.The grinding fluid distribution adjusting method comprises the steps that a plurality of arc-shaped areas of different sizes are sequentially divided on the grinding face of a grinding pad, and the circle center of each arc-shaped area is the same as the circle center of the grinding pad; the groove depth of each circular arc area is detected; the standard groove depth of the grinding pad after grinding is obtained; and according to the comparison result of the groove depth of each arc-shaped area and the standard groove depth, the initial flow of the grinding fluid is adjusted, and the target flow of the grinding fluid is obtained. According to the comparison result of the groove depth of each arc-shaped area and the standard groove depth, the initial flow of the grinding fluid is adjusted, so that the grinding fluid can be uniformly distributed on the grinding surface, the problem of non-uniform distribution of the grinding fluid caused by uniform change of the grooves of each arc-shaped area is solved, the grinding efficiency is improved, and the grinding quality is improved. And the wafer planarization quality is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for adjusting the distribution of a polishing liquid and a spraying device for the polishing liquid. Background Art

[0002] With the continuous development of the semiconductor industry, Chemical Mechanical Polishing (CMP) technology is considered to be the only process technology that can provide global and local planarization of wafers. Chemical mechanical polishing technology has been widely used in the removal and planarization of interlayer dielectrics, metal layers (such as tungsten plugs, copper wiring), and shallow trench isolation, becoming one of the fastest growing areas in semiconductor manufacturing technology.

[0003] With the continuous development of the semiconductor industry, the control of product process windows, in terms of CMP, the requirements for planarization of advanced processes are becoming more and more stringent. The higher the precision of planarization, the better the product quality. In the existing CMP device, the polishing pad is set to rotate with the polishing platform. After the wafer is adsorbed by the polishing head, it contacts the polishing pad and rotates under pressure. The wafer is flattened under the action of the polishing liquid.

[0004] Typically, when the polishing pad is used for a certain period of time, the uniformity of the surface grooves of the polishing pad deteriorates, causing the polishing liquid to be unable to be evenly distributed in the grooves of the polishing pad, affecting the polishing efficiency and reducing the quality of wafer planarization. Summary of the invention

[0005] The purpose of the present invention is to provide a method for adjusting the distribution of grinding liquid and a spraying device for grinding liquid, so as to ensure the uniformity of the distribution of grinding liquid on the grinding pad and improve the grinding efficiency.

[0006] To achieve the above object, in a first aspect, the present invention provides a method for adjusting the distribution of a grinding liquid, comprising:

[0007] A plurality of arc-shaped areas of different sizes are sequentially divided on the grinding surface of the grinding pad, and the center of each arc-shaped area is the same as the center of the grinding pad;

[0008] Detecting the groove depth of each of the arc-shaped areas;

[0009] Obtaining a standard groove depth after grinding by the grinding pad;

[0010] According to the comparison result of the groove depth of each arc-shaped area and the standard groove depth, the initial flow rate of the grinding liquid is adjusted to obtain the target flow rate of the grinding liquid.

[0011] In some embodiments, adjusting the initial flow rate of the grinding liquid according to the comparison result of the groove depth of each arc-shaped area with the standard groove depth includes:

[0012] When the groove depth of the arc-shaped area is greater than the standard groove depth, reducing the initial flow rate of the grinding liquid;

[0013] When the groove depth of the arc-shaped area is less than the standard groove depth, the initial flow rate of the grinding liquid is increased.

[0014] In some embodiments, when the groove depth of the arc-shaped area is greater than the standard groove depth, reducing the initial flow rate of the grinding liquid includes:

[0015] moving the spraying member above the grinding surface;

[0016] Controlling the spraying member to move on a plane parallel to the grinding surface, with the nozzle of the spraying member facing the grinding surface;

[0017] When the spraying member moves so that the groove depth of the arc-shaped area toward which the nozzle is directed is greater than the standard groove depth, the nozzle reduces the flow rate of spraying the grinding liquid.

[0018] In some embodiments, when the groove depth of the arc-shaped area is less than the standard groove depth, increasing the initial flow rate of the grinding liquid includes:

[0019] When the spraying member moves so that the groove depth of the arc-shaped area toward which the nozzle is directed is smaller than the standard groove depth, the nozzle increases the flow rate of spraying the grinding liquid.

[0020] In some embodiments, the number of the arc-shaped regions is at least 2, and a plurality of the arc-shaped regions cover the entire grinding surface.

[0021] In some embodiments, adjusting the initial flow rate of the grinding liquid according to the comparison result of the groove depth of each arc-shaped area with the standard groove depth to obtain the target flow rate of the grinding liquid includes:

[0022] Obtaining the initial flow rate of the grinding liquid;

[0023] Calculating the actual wear amount of the polishing pad caused by the wafer according to the detected groove depth of the arc-shaped area;

[0024] Calculating a standard wear amount of the polishing pad worn by the wafer according to the standard groove depth;

[0025] Calculate the difference between the actual wear amount and the standard wear amount and multiply it by the initial flow rate to obtain a flow adjustment value;

[0026] The initial flow rate is adjusted by the flow adjustment value to obtain the target flow rate of the polishing liquid.

[0027] In a second aspect, the present invention provides a spraying device for a polishing liquid, characterized in that the method for adjusting the distribution of the polishing liquid can be implemented, and the spraying device comprises:

[0028] A polishing pad, wherein the polishing pad has a polishing surface, and the polishing surface is sequentially divided into a plurality of arc-shaped areas of different sizes, and the center of each of the arc-shaped areas is the same as the center of the polishing pad;

[0029] A depth detection sensor is disposed near the polishing pad and is used to detect the depth of the groove of each of the arc-shaped areas;

[0030] A spraying member, disposed near the polishing pad, for spraying polishing liquid onto the polishing surface;

[0031] The controller is electrically connected to the spraying member and the depth detection sensor, and is used to control the flow rate of the grinding liquid sprayed by the spraying member.

[0032] In some embodiments, it further includes a grinding head disposed opposite to the grinding pad;

[0033] The grinding head is used for carrying a wafer and can drive the wafer to move toward the grinding pad so that the wafer contacts the grinding pad.

[0034] In some embodiments, a trimmer is further included on the side of the grinding pad, and the trimmer is used to trim the grinding surface.

[0035] In some embodiments, further comprising a grinding station;

[0036] The grinding pad is arranged on the grinding table, and the grinding table is used for driving the grinding pad to rotate.

[0037] The beneficial effects of a method for adjusting the distribution of the grinding liquid and a device for spraying the grinding liquid provided by the present invention are:

[0038] By dividing the grinding surface into several arc-shaped areas of different sizes and detecting the depth of the groove of each arc-shaped area, the initial flow rate of the grinding liquid is adjusted according to the comparison result of the groove depth of each arc-shaped area with the standard groove depth, so that the grinding liquid can be evenly distributed on the grinding surface to solve the problem of uneven distribution of the grinding liquid caused by the change of the uniformity of the groove of each arc-shaped area, thereby improving the grinding efficiency and the quality of wafer flattening. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1A top view of a polishing pad after use and a cross-sectional view at AA in the prior art;

[0040] Figure 2 A flow chart of a method for adjusting the distribution of abrasive liquid according to an embodiment of the present invention;

[0041] Figure 3 A top view of the polishing pad according to an embodiment of the present invention;

[0042] Figure 4 A flow chart showing how to adjust the initial flow rate to obtain a target flow rate of the polishing liquid according to an embodiment of the present invention;

[0043] Figure 5 A front view of a spraying device for abrasive liquid according to an embodiment of the present invention;

[0044] Figure 6 A top view of a spraying device for a grinding liquid according to an embodiment of the present invention.

[0045] Reference numerals:

[0046] Grinding pad 1, arc-shaped area 11, depth detection sensor 2, spraying member 3, controller 4, grinding head 5, dresser 6, grinding table 7. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0048] With the development of the semiconductor industry, the requirements for wafer planarization are becoming more and more stringent. In the prior art, when the polishing pad is used for a certain period of time, the surface groove uniformity of the polishing pad will deteriorate, resulting in the inability of the polishing liquid to be evenly distributed in the grooves of the polishing pad, thereby affecting the polishing efficiency and reducing the quality of wafer planarization.

[0049] Figure 1 It is a top view and a cross-sectional view at AA of the polishing pad after use in the prior art.

[0050] like Figure 1As shown, after the polishing pad 1 has been used for a certain period of time, the depth of the grooves in the middle area of ​​the polishing pad 1 will be smaller than the depth of the grooves in the edge area of ​​the polishing pad, which will cause the surface groove uniformity of the polishing pad 1 to deteriorate and make the polishing liquid unable to be evenly distributed in the grooves of the polishing pad.

[0051] Figure 2 A flow chart of a method for adjusting the distribution of polishing liquid according to an embodiment of the present invention.

[0052] In order to solve the problems existing in the prior art, the embodiment of the present invention provides a method for adjusting the distribution of the grinding liquid, referring to Figure 2 As shown, the method includes:

[0053] S201: Sequentially dividing a plurality of arc-shaped areas of different sizes on the grinding surface of the grinding pad, wherein the center of each arc-shaped area is the same as the center of the grinding pad.

[0054] like Figure 3 As shown, in this step, the arc-shaped area 11 is divided in sequence by adjacent circles of different diameters, and a plurality of arc-shaped areas 11 of different sizes cover the entire grinding surface of the grinding pad 1 .

[0055] It should be noted that the number of the arc-shaped areas 11 is set to at least 2. In this embodiment, the number of the arc-shaped areas 11 is divided into 7, and the 7 arc-shaped areas 11 are respectively represented by Z1, Z2, Z3, Z4, Z5, and Z6 are represented by Z7. In some embodiments, the number of the arc-shaped areas 11 can be 2-6, 8, 10 or 12, etc.

[0056] S202: Detect the groove depth of each arc-shaped area.

[0057] In this step, a depth detection sensor may be used to detect the groove depth of each arc-shaped area 11. The frequency of the groove depth detection of each arc-shaped area may be a timed detection or a real-time detection, or may be performed after processing a specified number of wafers.

[0058] S203: Obtaining the standard groove depth after grinding by the grinding pad.

[0059] It should be noted that, since the standard groove depths after grinding with the same type of grinding pads are the same, the standard groove depths after grinding with different types of grinding pads can be measured in advance to facilitate acquisition at this time.

[0060] Combination Figure 3As shown, the standard groove depth can be measured by taking the average value of the groove depth of the arc-shaped area (Z7) at the edge of the grinding surface and the groove depth of the arc-shaped area (Z1) in the middle of the grinding surface. Alternatively, the standard groove depth can be taken as half of the initial groove depth of the grinding surface (i.e., the groove depth when the grinding surface is not grinding a wafer).

[0061] S204: adjusting the initial flow rate of the grinding liquid according to the comparison result of the groove depth of each arc-shaped area with the standard groove depth to obtain the target flow rate of the grinding liquid.

[0062] In this step, when the groove depth of the arc-shaped area is greater than the standard groove depth, the initial flow rate of the grinding liquid is reduced so that the final target flow rate of the grinding liquid is less than the initial flow rate of the grinding liquid at the beginning. When the groove depth of the arc-shaped area is less than the standard groove depth, the flow rate of the grinding liquid is increased so that the final target flow rate of the grinding liquid is greater than the initial flow rate of the grinding liquid at the beginning.

[0063] Specifically, the spraying member is moved to above the grinding surface, and then the spraying member is controlled to move evenly on a plane parallel to the grinding surface, with the nozzle of the spraying member facing the grinding surface.

[0064] During the movement of the spraying member, when the groove depth of the arc-shaped area toward which the nozzle is directed is greater than the standard groove depth, the nozzle reduces the flow rate of spraying the grinding liquid to reduce the grinding liquid in the arc-shaped area corresponding to the nozzle.

[0065] When the spraying member moves so that the groove depth of the arc-shaped area toward which the nozzle is directed is less than the standard groove depth, the nozzle increases the flow rate of the polishing liquid to increase the polishing liquid in the arc-shaped area corresponding to the nozzle.

[0066] Figure 4 The present invention provides an embodiment of adjusting the initial flow rate to obtain a flow chart of the target flow rate of the grinding liquid.

[0067] refer to Figure 4 As shown, adjusting the initial flow rate of the grinding liquid to obtain the target flow rate of the grinding liquid specifically includes the following steps:

[0068] S401: Obtaining the initial flow rate of the grinding liquid.

[0069] S402: Calculate the actual wear amount of the polishing pad caused by the wafer according to the detected groove depth of the arc-shaped area.

[0070] Combination Figure 3As shown, for example, in this embodiment, the initial groove depth of the arc-shaped area 11 (Z1) groove located in the central area of ​​the grinding surface is 35 mil. After the grinding pad 1 grinds 500 wafers, the depth of the groove in the arc-shaped area (Z1) becomes 10 mil, and the initial flow rate of the grinding liquid is 250 ml / min. The consumption of each wafer in the central area of ​​the grinding surface is (35-10) / 500=0.05 mil, that is, the actual wear of each wafer on the grinding pad 1 in this area is 0.05 mil.

[0071] S403: Calculating a standard wear amount of the polishing pad worn by the wafer according to the standard groove depth.

[0072] In this step, the standard groove depth can be set to half of the initial groove depth of the grinding pad, that is, the standard groove depth is 17.5 mil. Then the consumption of the grinding pad by each wafer should be (35-17.5) / 500=0.035 mil, indicating that the standard wear of the grinding pad by each wafer is 0.035 mil.

[0073] S404: Calculate the difference between the actual wear amount and the standard wear amount and multiply it by the initial flow rate to obtain a flow adjustment value.

[0074] In this step, the flow adjustment value is calculated to be 250×(0.05-0.035)=3.75 ml / min.

[0075] S405: adjusting the initial flow rate by the flow rate adjustment value to obtain the target flow rate of the polishing liquid.

[0076] Since this area is located in the central area of ​​the polishing pad, the flow rate of the polishing liquid needs to be increased, so the target flow rate of the polishing liquid is 250+3.75=253.75 ml / min.

[0077] It should be noted that when the groove depth of the arc-shaped area is located at the edge of the polishing pad, after the flow adjustment value is calculated in the above manner, the target flow rate of the polishing liquid is obtained by subtracting the flow adjustment value from the initial flow rate of the polishing liquid.

[0078] For example, the initial depth of the groove in the arc-shaped area (Z7) located at the edge area of ​​the grinding pad 1 is 35 mil. After the grinding pad 1 grinds 500 wafers, the depth of the groove in the arc-shaped area (Z7) becomes 25 mil, and the initial flow rate of the grinding liquid is 250 ml / min. The consumption of each wafer on the center area of ​​the grinding surface is (35-25) / 500=0.02 mil, indicating that the actual wear of each wafer on the grinding pad 1 in the arc-shaped area (Z7) is 0.02 mil.

[0079] Similarly, the standard groove depth is set to half of the initial groove depth of the grinding pad, that is, the standard groove depth is 17.5 mil, then the consumption of the grinding pad by each wafer should be (35-17.5) / 500=0.035 mil, indicating that the standard wear of the grinding pad by each wafer is 0.035 mil.

[0080] The flow adjustment value is calculated to be 250*(0.035-0.02)=3.75 ml / min. Since the area is located at the edge of the polishing pad, the flow of the polishing liquid needs to be reduced, so the target flow of the polishing liquid is 250-3.75=246.25 ml / min.

[0081] In this embodiment, a number of arc-shaped areas 11 of different sizes are divided on the grinding surface, and the groove depth of each arc-shaped area is detected. According to the comparison result of the groove depth of each arc-shaped area with the standard groove depth, the initial flow rate of the grinding liquid is adjusted so that the grinding liquid can be evenly distributed on the grinding surface to solve the problem of uneven distribution of the grinding liquid caused by the change of groove uniformity of each arc-shaped area, thereby improving the grinding efficiency and the quality of wafer flattening.

[0082] refer to Figure 5 and Figure 6 As shown, an embodiment of the present invention provides a spraying device for abrasive liquid, which can implement the above-mentioned method for adjusting the distribution of abrasive liquid, and the spraying device includes a grinding pad 1, a depth detection sensor 2, a spraying member 3 and a controller 4. Among them, the upper surface of the grinding pad 1 is a grinding surface, and the grinding surface is divided into a plurality of arc-shaped areas 11 of different sizes in sequence, and the center of each arc-shaped area 11 is the same as the center of the grinding pad. It should be noted that the arc-shaped area 11 is divided in sequence by adjacent circles of different diameters, and a plurality of arc-shaped areas 11 of different sizes cover the entire grinding surface.

[0083] The depth detection sensor 2 is arranged near the polishing pad 1, and the depth detection sensor 2 can be located above the polishing pad 1 through a connecting piece (not shown in the figure), so as to detect the groove depth of each arc-shaped area 11. The spraying member 3 is arranged near the polishing pad 1, and the spraying member 3 is connected to a moving mechanism (not shown in the figure), and the moving mechanism is used to drive the spraying member 3 to move evenly above the polishing pad 1, so that the polishing liquid in the spraying member 3 is sprayed onto the polishing surface through the nozzle. The controller 4 is electrically connected to the spraying member 3 and the depth detection sensor 2, and the information of the standard groove depth can be set and stored in the controller 4, and the information of the groove depth of the arc-shaped area 11 detected by the depth detection sensor 2 can also be received. The controller 4 controls the flow rate of the polishing liquid sprayed by the spraying member 3 after calculation.

[0084] Furthermore, the spraying device further comprises a grinding head 5 arranged opposite to the grinding pad 1, the grinding head 5 is located above the grinding pad 1 and is used for adsorbing and carrying the wafer, and can drive the wafer to move toward the grinding pad 1 so that the wafer contacts the grinding pad 1. The grinding pad 1 is arranged on the grinding table 7, and the grinding table 7 is used for driving the grinding pad 1 to rotate.

[0085] In addition, the spraying device further comprises a dresser 6 arranged at the side of the polishing pad 1, and the dresser 6 is used to dress the polishing surface of the polishing pad 1 to improve the uniformity of the polishing surface.

[0086] In this embodiment, the depth detection sensor 2 may be a distance sensor, and the distance sensor may detect in real time the groove depth of each arc-shaped area 11 on the polishing pad 1. Then the controller 4 adjusts the initial flow rate of the polishing liquid according to the comparison result between the groove depth of each arc-shaped area 11 and the standard groove depth, so that the polishing liquid can be evenly distributed on the polishing surface.

[0087] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A method for adjusting the distribution of a grinding liquid, characterized in that: include: A plurality of arc-shaped areas of different sizes are sequentially divided on the grinding surface of the grinding pad, and the center of each arc-shaped area is the same as the center of the grinding pad; Detecting the groove depth of each of the arc-shaped areas; Obtaining a standard groove depth after grinding by the grinding pad; According to the comparison result of the groove depth of each arc-shaped area and the standard groove depth, the initial flow rate of the grinding liquid is adjusted to obtain the target flow rate of the grinding liquid.

2. The method for adjusting the distribution of the grinding liquid according to claim 1, characterized in that: The step of adjusting the initial flow rate of the grinding liquid according to the comparison result between the groove depth of each arc-shaped area and the standard groove depth comprises: When the groove depth of the arc-shaped area is greater than the standard groove depth, reducing the initial flow rate of the grinding liquid; When the groove depth of the arc-shaped area is less than the standard groove depth, the initial flow rate of the grinding liquid is increased.

3. The method for adjusting the distribution of the grinding liquid according to claim 2, characterized in that: When the groove depth of the arc-shaped area is greater than the standard groove depth, reducing the initial flow rate of the grinding liquid comprises: moving the spraying member above the grinding surface; Controlling the spraying member to move on a plane parallel to the grinding surface, with the nozzle of the spraying member facing the grinding surface; When the spraying member moves so that the groove depth of the arc-shaped area toward which the nozzle is directed is greater than the standard groove depth, the nozzle reduces the flow rate of spraying the grinding liquid.

4. The method for adjusting the distribution of the grinding liquid according to claim 3, characterized in that: When the groove depth of the arc-shaped area is less than the standard groove depth, increasing the initial flow rate of the grinding liquid comprises: When the spraying member moves so that the groove depth of the arc-shaped area toward which the nozzle is directed is smaller than the standard groove depth, the nozzle increases the flow rate of spraying the grinding liquid.

5. The method for adjusting the distribution of the grinding liquid according to any one of claims 1 to 4, characterized in that: The number of the arc-shaped areas is at least 2, and a plurality of the arc-shaped areas cover the entire grinding surface.

6. The method for adjusting the distribution of the grinding liquid according to claim 1, characterized in that: The step of adjusting the initial flow rate of the grinding liquid according to the comparison result between the groove depth of each arc-shaped area and the standard groove depth to obtain the target flow rate of the grinding liquid comprises: Obtaining the initial flow rate of the grinding liquid; Calculating the actual wear amount of the polishing pad caused by the wafer according to the detected groove depth of the arc-shaped area; Calculating a standard wear amount of the polishing pad worn by the wafer according to the standard groove depth; Calculate the difference between the actual wear amount and the standard wear amount and multiply it by the initial flow rate to obtain a flow adjustment value; The initial flow rate is adjusted by the flow adjustment value to obtain the target flow rate of the polishing liquid.

7. A spraying device for abrasive liquid, characterized in that: The method for adjusting the distribution of the grinding liquid according to any one of claims 1 to 6 can be implemented, wherein the spraying device comprises: A polishing pad, wherein the polishing pad has a polishing surface, and the polishing surface is sequentially divided into a plurality of arc-shaped areas of different sizes, and the center of each of the arc-shaped areas is the same as the center of the polishing pad; A depth detection sensor is disposed near the polishing pad and is used to detect the depth of the groove of each of the arc-shaped areas; A spraying member, disposed near the polishing pad, for spraying polishing liquid onto the polishing surface; The controller is electrically connected to the spraying member and the depth detection sensor, and is used to control the flow rate of the grinding liquid sprayed by the spraying member.

8. The polishing liquid spraying device according to claim 7, characterized in that: Also included is a grinding head disposed opposite to the grinding pad; The grinding head is used for carrying a wafer and can drive the wafer to move toward the grinding pad so that the wafer contacts the grinding pad.

9. The polishing liquid spraying device according to claim 7, characterized in that: It also includes a dresser arranged on the side of the grinding pad, and the dresser is used to dress the grinding surface.

10. The polishing liquid spraying device according to any one of claims 7 to 9, characterized in that: Also included is a grinding station; The grinding pad is arranged on the grinding table, and the grinding table is used for driving the grinding pad to rotate.

Images