Method for improving via etch bias
By monitoring the lateral deviation of the via opening at the wafer edge within the etching chamber and replacing the focusing ring, the problem of lateral deviation in via etching was solved, improving wafer edge yield and extending the service life of the etching chamber.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI HUALI INTEGRATED CIRCUIT CORP
- Filing Date
- 2026-03-31
- Publication Date
- 2026-07-10
AI Technical Summary
Existing plasma etching processes suffer from via etching side deviation, which causes the via openings in the wafer edge region to shift towards the wafer center, affecting yield.
By monitoring the lateral deviation of the via opening in the wafer edge region within the etching cavity, the first focusing ring is replaced with a second focusing ring. The initial thickness of the second focusing ring is greater than that of the first focusing ring, and the material can be Si or SiC, with the thickness increased by 20% to 50% to avoid the occurrence of lateral deviation.
It effectively improves or eliminates the side deviation phenomenon in through-hole etching, increases the yield at the far edge, extends the continuous running time of the etching cavity, and reduces plasma loss.
Smart Images
Figure CN122373789A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for manufacturing semiconductor integrated circuits, and more particularly to a method for improving the side bias of via etching. Background Technology
[0002] The existing plasma etching process has a hardware defect in the etching cavity. After the top-layer via is etched, there is a long-term phenomenon of the hole radial offset from the wafer center due to the weak point of the wafer edge. As the radio frequency (RF) time increases, the loss of the focus ring increases, and the offset phenomenon becomes more and more serious.
[0003] like Figure 1 The image shows photographs of via openings in different wafer regions as the RF time in the etching chamber increases during existing plasma etching processes; the photographs of each via opening 102 are located in... Figure 1 In the table, each grid point in the first column corresponds to the RF hours, i.e., the usage time, and the first row corresponds to the coordinates of the through-hole opening 102. Figure 1 The via openings 102 in the dashed frame 101 are located in the edge region of the wafer, i.e., the region with a radius of 146mm to 148mm. It can be seen that each via opening 102 in the dashed frame 101 has a lateral offset, i.e., it is offset towards the center of the wafer.
[0004] like Figure 2 The image shown is a photograph of the via opening in the edge region of the wafer during the initial RF stage in the etching chamber of an existing plasma etching process; it can be seen that the via opening 102a has a lateral offset.
[0005] like Figure 3 The image shown is a photograph of the via opening in the edge region of the wafer at the end of the RF stage in the etching chamber during a conventional plasma etching process. It can be seen that the via opening 102b has a lateral offset, and the lateral offset of the via opening 102b is greater than... Figure 2 Lateral deviation of the through hole opening 102a in the middle.
[0006] Cross-sectional photographs of via openings with lateral deviation formed by existing plasma etching processes show that the via openings are laterally deflected. Summary of the Invention
[0007] The technical problem to be solved by the present invention is to provide a method for improving the side deviation of via etching, which can improve the side deviation phenomenon of via and thus improve the yield at the far edge.
[0008] To solve the above-mentioned technical problems, the method for improving the side deviation of through-hole etching provided by the present invention includes the following steps: Step 1: Provide an etching cavity, which includes a wafer placement area and a first focus ring located on the periphery of the wafer placement area. The first focus ring has a first initial thickness.
[0009] Step 2: Continuous running is performed using the etching chamber. During the continuous running process, multiple wafers are sequentially placed into the etching chamber for plasma etching to form via openings. The direction of the via openings in the edge region of the wafer is monitored to see if they will deviate laterally. When there is no deviation in the via openings in the edge region of the wafer, the continuous running continues.
[0010] Step 3: When the via opening in the edge region of the wafer is detected to be laterally deviated, the continuous shipment process is stopped, the final thickness of the first focusing ring is measured, and the first shipment quantity of the continuous shipment process is counted.
[0011] Step 4: When the first quantity of goods shipped is less than the second quantity of goods shipped as set in the maintenance cycle, the first focusing ring is replaced with a second focusing ring having a second initial thickness greater than the first initial thickness.
[0012] A further improvement is that the second initial thickness ensures that when the second focusing ring is used to replace the first focusing ring for step two, the via openings in the edge region of the wafer are not laterally deflected before the number of consecutive runs reaches the second number of runs.
[0013] A further improvement is that, when replacing the first focusing ring with the second focusing ring in step two, the maintenance is performed when the number of continuously running goods reaches the second number of running goods. The maintenance includes replacing the second focusing ring, which has consumed part of its thickness, with a new second focusing ring having the second initial thickness.
[0014] A further improvement is that the second initial thickness is greater than 120% to 150% of the first initial thickness.
[0015] A further improvement is that the material of the first focusing ring includes Si.
[0016] A further improvement is that the material of the second focusing ring includes Si or SiC.
[0017] A further improvement is that the wafer placement area is located on the top surface of the electrostatic chuck (ESC).
[0018] A further improvement is that the electrostatic chuck is made of ceramic.
[0019] A further improvement is that the first focusing ring includes: a first segment structure and a second segment structure.
[0020] The first segment is located inside the second segment, the top surface of the first segment is lower than the top surface of the electrostatic chuck, and the inner side of the first segment is fitted onto the outer side of the electrostatic chuck.
[0021] The top surface of the second segment is higher than the top surface of the first segment, and the second segment also has a first inclined inner side surface, which connects from the outside of the top surface of the first segment to the inside of the top surface of the second segment, and the first initial thickness is the thickness of the second segment.
[0022] A further improvement is that the second focusing ring includes a third segment structure and a fourth segment structure.
[0023] The third segment is located inside the fourth segment, the top surface of the third segment is lower than the top surface of the electrostatic chuck, and the inner side of the third segment is fitted onto the outer side of the electrostatic chuck.
[0024] The top surface of the fourth segment is higher than the top surface of the third segment, and the fourth segment also has a second inclined inner side surface, which connects from the outside of the top surface of the third segment to the inside of the top surface of the fourth segment, and the second initial thickness is the thickness of the fourth segment.
[0025] A further improvement is that the thickness of the third segment is the same as the thickness of the first segment.
[0026] A further improvement is that the second segment structure also has a first convex segment, which is located at the outermost end of the second segment structure. The top surface of the first convex segment is the top surface of the second segment structure, and the bottom surface of the first convex segment is the top surface of the first segment structure.
[0027] A further improvement is that the fourth segment structure also has a second convex segment, which is located at the outermost end of the fourth segment structure. The top surface of the second convex segment is the top surface of the fourth segment structure, and the bottom surface of the second convex segment is higher than the bottom surface of the third segment structure.
[0028] A further improvement is that, when replacing the first focusing ring with the second focusing ring in step two, when the number of continuously running goods reaches the second number of running goods, the thickness consumed by the second focusing ring before replacement is also measured.
[0029] A further improvement is that, in step two, when performing plasma etching on each of the wafers, the etching rate before and after plasma etching is also measured.
[0030] A further improvement is that the through-hole opening is a top-layer through-hole opening.
[0031] This invention monitors the lateral deviation of via openings in the edge regions of each wafer during continuous etching in an etching chamber. When lateral deviation is detected and the corresponding first etching quantity is less than the second etching quantity set for the maintenance cycle, a second focusing ring with a second initial thickness replaces the first focusing ring. This second focusing ring is then used in subsequent etching processes, i.e., plasma etching. Since the second initial thickness of the second focusing ring is greater than the first initial thickness of the first focusing ring, the first etching quantity achievable before lateral deviation occurs in step two can be increased, preferably exceeding the second etching quantity. Maintenance is performed when the etching quantity reaches the second etching quantity, and the second focusing ring is replaced as a consumable during maintenance. Therefore, lateral deviation does not occur during continuous etching in an etching chamber within a maintenance cycle. Thus, this invention can improve or even eliminate via lateral deviation and thereby improve yield at the far edge. Attached Figure Description
[0032] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments: Figure 1 These are photographs of via openings in different wafer regions as the RF time in the etching chamber increases in existing plasma etching processes. Figure 2 This is a photograph of the via openings in the edge region of the wafer during the initial RF stage in the etching chamber of an existing plasma etching process; Figure 3 This is a photograph of the via openings in the edge region of the wafer during the final stage of the RF phase in the etching chamber of an existing plasma etching process. Figure 4 This is a flowchart of a method for improving the side deviation of through-hole etching according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the etching cavity structure when the first focusing ring has a first initial thickness in the method for improving the side deviation of through-hole etching according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the etching cavity structure when the first focusing ring has a final thickness in the method for improving the side deviation of through-hole etching according to an embodiment of the present invention; Figure 7 This is a perspective view of the first focusing ring in the method for improving the side deviation of through-hole etching according to an embodiment of the present invention; Figure 8This is a cross-sectional view of the first focusing ring in the method for improving the side deviation of through-hole etching according to an embodiment of the present invention; Figure 9 This is a cross-sectional view of the second focusing ring in the method for improving the side deviation of through-hole etching according to an embodiment of the present invention. Detailed Implementation
[0033] like Figure 4 The diagram shown is a flowchart of a method for improving the side deviation of via etching according to an embodiment of the present invention; as shown Figure 5 The diagram shown is a schematic representation of the etching cavity structure when the first focusing ring 203 has a first initial thickness in the method for improving the side deviation of through-hole etching according to an embodiment of the present invention; as shown... Figure 6 The diagram shown is a schematic representation of the etching cavity structure when the first focusing ring 203 has a final thickness in the method for improving the lateral deviation of through-hole etching according to an embodiment of the present invention. The method for improving the lateral deviation of through-hole etching according to an embodiment of the present invention includes the following steps: Step 1, such as Figure 5 As shown, an etching cavity is provided, which includes a wafer placement area and a first focusing ring 203 located on the periphery of the wafer placement area, the first focusing ring 203 having a first initial thickness.
[0034] In this embodiment of the invention, the wafer placement area is located on the top surface of the electrostatic chuck 201.
[0035] The electrostatic chuck 201 is made of ceramic. Figure 5 In this context, the electrostatic chuck 201 is also referred to as ESC ceramic.
[0036] In some embodiments, the material of the first focusing ring 203 includes Si.
[0037] Step 2: Continuous processing is performed using the etching chamber. During continuous processing, multiple wafers 202 are sequentially placed into the etching chamber for plasma etching to form via openings. The direction of the via openings in the edge region of the wafers 202 is monitored to see if they will deviate laterally. The direction of the deviation is towards the center of the wafers 202. When there is no deviation in the via openings in the edge region of the wafers 202, the continuous processing continues.
[0038] like Figure 5 As shown, during plasma etching, energy is provided by radio frequency (RF) to act on the process gas to form plasma 205. Plasma 205 forms a sheath layer 204 on the surface of the wafer 202. The presence of the sheath layer 204 will affect the direction of plasma 205 towards the ions in the wafer 202, i.e., the etching direction 206.
[0039] In some embodiments, the through-hole opening is a top-layer through-hole opening.
[0040] Step 3: When the via opening in the edge region of the wafer 202 is detected to be laterally deviated, the continuous shipment process is stopped, the final thickness of the first focusing ring 203 is measured, and the first shipment quantity of the continuous shipment process is counted.
[0041] In this embodiment of the invention, the bombardment effect of the plasma 205 not only etches the film layer on the wafer 202, but also consumes the first focusing ring 203. As the thickness of the first focusing ring 203 is consumed, the morphology of the sheath layer 204 in the edge region also changes. For example... Figure 6 The diagram shown is a schematic representation of the etching cavity structure when the first focusing ring has a final thickness in the method for improving the side deviation of through-hole etching according to an embodiment of the present invention; Figure 6 As shown, the sheath 204 in the edge region will bend downwards, and the corresponding etching direction 206a will also deviate from the etching direction 206 in the middle region. Moreover, the etching direction 206a deviates towards the central region of the wafer 202. Therefore, the lateral deviation direction of the via opening formed by etching is also deviating towards the central region of the wafer 202.
[0042] Step 4: When the first quantity of goods shipped is less than the second quantity of goods shipped as set in the maintenance cycle, the first focusing ring 203 is replaced with a second focusing ring 204 having a second initial thickness, the second initial thickness being greater than the first initial thickness.
[0043] In this embodiment of the invention, the second initial thickness ensures that when the second focusing ring 204 is used to replace the first focusing ring 203 for step two, the via openings in the edge region of the wafer 202 are not laterally deflected before the number of consecutive shipments reaches the second shipment quantity.
[0044] When replacing the first focusing ring 203 with the second focusing ring 204 in step two, maintenance is performed when the number of continuously running goods reaches the second running quantity. This maintenance includes replacing the second focusing ring 204, which has lost some thickness, with a new second focusing ring 204 having the second initial thickness. It can be seen that in this embodiment of the invention, since the second focusing ring 204 is replaced with a new one before the conditions for lateral deviation are met, lateral deviation of the through-hole opening will not occur during the entire service life of the second focusing ring 204.
[0045] In this embodiment of the invention, when the second focusing ring 204 is used to replace the first focusing ring 203 for step two, when the number of continuously running goods reaches the second number of running goods, the thickness consumed by the second focusing ring 204 before replacement is also measured.
[0046] In step two, when performing plasma etching on each of the wafers 202, the method further includes measuring the etching rate before and after plasma etching.
[0047] In some embodiments, the material of the second focusing ring 204 includes Si or SiC.
[0048] The second initial thickness is greater than 120% to 150% of the first initial thickness.
[0049] like Figure 7 The figure shown is a perspective view of the first focusing ring in the method for improving the side deviation of through-hole etching according to an embodiment of the present invention; it can be seen that the first focusing ring 203 is a ring structure.
[0050] like Figure 8 The diagram shown is a cross-sectional view of the first focusing ring in the method for improving the side deviation of through-hole etching according to an embodiment of the present invention, for example, a cross-sectional view at frame 301. The first focusing ring 203 includes: a first segment structure 203a and a second segment structure 203b.
[0051] The first segment structure 203a is located inside the second segment structure 203b. The top surface of the first segment structure 203a, i.e. the BB surface, is lower than the top surface of the electrostatic chuck 201, i.e. the CC surface. The inner side of the first segment structure 203a is fitted onto the outer side of the electrostatic chuck 201.
[0052] The top surface of the second segment structure 203b, i.e., the DD surface, is higher than the top surface of the first segment structure 203a, and the second segment structure 203b also has a first inclined inner side surface, which connects from the outer side of the top surface of the first segment structure 203a to the inner side of the top surface of the second segment structure 203b, and the first initial thickness is the thickness of the second segment structure 203b.
[0053] In this embodiment of the invention, the second segment structure 203b further has a first convex segment 203b1, the first convex segment 203b1 is located at the outermost end of the second segment structure 203b, the top surface of the first convex segment 203b1 is the top surface of the second segment structure 203b, and the bottom surface of the first convex segment 203b1 is higher than the bottom surface of the first segment structure 203a.
[0054] like Figure 9 The diagram shown is a cross-sectional view of the second focusing ring in the method for improving the side deviation of through-hole etching according to an embodiment of the present invention; the second focusing ring 204 includes: a third segment structure 204a and a fourth segment structure 204b.
[0055] The third segment structure 204a is located inside the fourth segment structure 204b. The top surface of the third segment structure 204a is lower than the top surface of the electrostatic chuck 201. The inner side of the third segment structure 204a is sleeved on the outer side of the electrostatic chuck 201.
[0056] The top surface of the fourth segment structure 204b, i.e., the EE surface, is higher than the top surface of the third segment structure 204a, and the fourth segment structure 204b also has a second inclined inner surface, which connects from the outer side of the top surface of the third segment structure 204a to the inner side of the top surface of the fourth segment structure 204b, and the second initial thickness is the thickness of the fourth segment structure 204b.
[0057] In this embodiment of the invention, the thickness of the third segment 204a is the same as the thickness of the first segment 203a. Therefore, this embodiment of the invention only needs to... Figure 8 The second focusing ring 204 can be obtained by increasing the thickness of the second segment structure 203b shown to form the fourth segment structure 204b.
[0058] The fourth segment structure 204b also has a second convex segment 204b1, which is located at the outermost end of the fourth segment structure 204b. The top surface of the second convex segment 204b1 is the top surface of the fourth segment structure 204b, and the bottom surface of the second convex segment 204b1 is higher than the bottom surface of the third segment structure 204a.
[0059] This invention monitors the lateral deviation of via openings in the edge regions of each wafer 202 during continuous etching in an etching chamber. When lateral deviation is detected and the corresponding first lateral deviation quantity is less than the second lateral deviation quantity set for the maintenance cycle, a second focusing ring 204 with a second initial thickness replaces the first focusing ring 203. The second focusing ring 204 is then used in subsequent etching processes, i.e., plasma etching. Since the second initial thickness of the second focusing ring 204 is greater than the first initial thickness of the first focusing ring 203, the first lateral deviation quantity achievable before lateral deviation occurs in step two can be increased, preferably exceeding the second lateral deviation quantity. Maintenance is performed when the lateral deviation quantity reaches the second lateral deviation quantity. During maintenance, the second focusing ring 204 is replaced as a consumable. Therefore, lateral deviation does not occur during continuous etching in an etching chamber within a maintenance cycle. Thus, this invention can improve or even eliminate via lateral deviation and thereby improve yield at the far edge.
[0060] The embodiments of the present invention can improve the radial wafer center deviation of the far edge hole during the etching process of the top layer via. By increasing the thickness of the existing focus ring by 20% to 50% and changing the material from Si to SiC, the loss of SiC under F-containing gas etching is less than that of pure silicon. Therefore, it can avoid the via displacement caused by plasma deviation after etching consumption.
[0061] The present invention has been described in detail above through specific embodiments, but these are not intended to limit the invention. Many modifications and improvements can be made by those skilled in the art without departing from the principles of the invention, and these should also be considered within the scope of protection of the present invention.
Claims
1. A method for improving the etching bias of through-holes, characterized in that, Includes the following steps: Step 1: Provide an etching cavity, which includes a wafer placement area and a first focusing ring located on the periphery of the wafer placement area, the first focusing ring having a first initial thickness; Step 2: Continuous running is performed using the etching chamber. During the continuous running process, multiple wafers are sequentially placed into the etching chamber for plasma etching to form via openings. The direction of the via openings in the edge region of the wafer is monitored to see if there is any lateral deviation. The lateral deviation is directed towards the center of the wafer. When there is no lateral deviation in the via openings in the edge region of the wafer, the continuous running continues. Step 3: When the via opening in the edge region of the wafer is detected to be laterally deviated, the continuous running process is stopped and the final thickness of the first focusing ring is measured and the first running quantity of the continuous running process is counted. Step 4: When the first quantity of goods shipped is less than the second quantity of goods shipped as set in the maintenance cycle, the first focusing ring is replaced with a second focusing ring having a second initial thickness greater than the first initial thickness.
2. The method for improving the etching bias of through-holes as described in claim 1, characterized in that: The second initial thickness ensures that when the second focusing ring is used to replace the first focusing ring for step two, the via openings in the edge region of the wafer are not laterally deflected before the number of consecutive runs reaches the second number of runs.
3. The method for improving the etching bias of through-holes as described in claim 2, characterized in that: When replacing the first focusing ring with the second focusing ring in step two, the maintenance is performed when the number of consecutive shipments reaches the second shipment quantity. The maintenance includes replacing the second focusing ring, which has consumed part of its thickness, with a new second focusing ring having the second initial thickness.
4. The method for improving the etching bias of through-holes as described in claim 2, characterized in that: The second initial thickness is greater than 120% to 150% of the first initial thickness.
5. The method for improving the etching bias of through-holes as described in claim 1, characterized in that: The material of the first focusing ring includes Si.
6. The method for improving the etching bias of through-holes as described in claim 6, characterized in that: The material of the second focusing ring includes Si or SiC.
7. The method for improving the etching bias of through-holes as described in claim 1, characterized in that: The wafer placement area is located on the top surface of the electrostatic chuck.
8. The method for improving the etching bias of through-holes as described in claim 8, characterized in that: The electrostatic chuck is made of ceramic.
9. The method for improving the etching bias of through-holes as described in claim 8, characterized in that: The first focusing ring includes: a first segment structure and a second segment structure; The first segment is located inside the second segment, the top surface of the first segment is lower than the top surface of the electrostatic chuck, and the inner side of the first segment is fitted onto the outer side of the electrostatic chuck. The top surface of the second segment is higher than the top surface of the first segment, and the second segment also has a first inclined inner side surface, which connects from the outside of the top surface of the first segment to the inside of the top surface of the second segment, and the first initial thickness is the thickness of the second segment.
10. The method for improving the etching side deviation of through-holes as described in claim 10, characterized in that: The second focusing ring includes: a third segment structure and a fourth segment structure; The third segment is located inside the fourth segment, the top surface of the third segment is lower than the top surface of the electrostatic chuck, and the inner side of the third segment is fitted onto the outer side of the electrostatic chuck. The top surface of the fourth segment is higher than the top surface of the third segment, and the fourth segment also has a second inclined inner side surface, which connects from the outside of the top surface of the third segment to the inside of the top surface of the fourth segment, and the second initial thickness is the thickness of the fourth segment.
11. The method for improving the etching side deviation of through-holes as described in claim 11, characterized in that: The thickness of the third segment is the same as the thickness of the first segment.
12. The method for improving the etching side deviation of through-holes as described in claim 10, characterized in that: The second segment structure also has a first convex segment, which is located at the outermost end of the second segment structure. The top surface of the first convex segment is the top surface of the second segment structure, and the bottom surface of the first convex segment is higher than the bottom surface of the first segment structure.
13. The method for improving the etching side deviation of through-holes as described in claim 11, characterized in that: The fourth segment structure also has a second convex segment, which is located at the outermost end of the fourth segment structure. The top surface of the second convex segment is the top surface of the fourth segment structure, and the bottom surface of the second convex segment is higher than the bottom surface of the third segment structure.
14. The method for improving the etching side deviation of through holes as described in claim 3, characterized in that: When replacing the first focusing ring with the second focusing ring in step two, when the number of continuously running goods reaches the second number of running goods, the thickness consumed by the second focusing ring before replacement is also measured.
15. The method for improving the etching side deviation of through-holes as described in claim 1, characterized in that: In step two, when performing plasma etching on each of the wafers, the method further includes measuring the etching rate before and after plasma etching.
16. The method for improving the etching side deviation of through-holes as described in claim 1, characterized in that: The through-hole opening is the top layer through-hole opening.