METHOD FOR ANALYZING WAFER TEST PARAMETERS

• US 20040193381A1
• Filed: 03/24/2003
• Published: 09/30/2004
• Est. Priority Date: 03/24/2003
• Status: Active Grant

• Current Assignee: Powerchip Semiconductor Manufacturing Corp. (Powerchip Technology Corporation)
• Original Assignee: Powerchip Semiconductor Corporation (Powerchip Technology Corporation)
• Inventors: Yueh, Ching-Ly, Tai, Hung-En
• Granted Patent: US 6,968,280 B2
• Time in Patent Office: Days
• US Class Current: 702/118
• CPC Class Codes: H01L 21/67253 Process monitoring, e.g. flow or thickness monitoring
• CPC Class Codes: H01L 21/67276 Production flow monitoring, e.g. for increasing throughput program-control systems per se G05B19/00, e.g. total factory control G05B19/418

Abstract

A plurality of lots of wafers, each lot of wafers having a lot number and each wafer of each lot having at least one test parameter generated by performing at least one wafer test item stored in a database, are divided into a high yield group and a low yield group. By analyzing the wafer test parameters of the wafers in the high yield group, a first standard value within a first range is obtained. A first comparison step is then performed to compare each wafer test parameter of each lot in the low yield group with the first standard value and delete lot numbers of lots with wafer test parameters within the first range. Finally, a first amount of residual lots in the low yield group is determined. In response to the first amount of residual lots in the low yield group not equaling to zero, a first searching step is performed to which item of sample test items, in-line QC items and process step items is related to the wafer test item of each residual lot in the low yield group in the database.

Claims

1. A method for analyzing wafer test parameters of a plurality of lots of wafers, each lot of the wafers comprising a lot number, each wafer of each lot comprising at least one wafer test parameter generated by performing at least one wafer test item stored in a database, parameters related to at least one sample test item, one in-line quality control (QC) item and one process step item related to the wafer test item being stored in the database, the method comprising:

dividing the lots of wafers into at least a high yield group and a low yield group based on yield of the lots;

obtaining a first standard value within a first range by analyzing the wafer test parameters of the wafers in the high yield group;

performing a first comparison step to compare each wafer test parameter of each lot in the low yield group with the first standard value and delete lot numbers of lots with wafer test parameters within the first range;

determining a first amount of residual lots in the low yield group after the first comparison step; and

in response to the first amount of residual lots in the low yield group not equaling to zero, performing a first searching step to determine which item of sample test items, in-line QC items and process step items is related to the wafer test item of each residual lot in the low yield group from the database.

2. The method of claim 1 wherein further steps are needed when the sample test item is determined to be related to the wafer test item in the first searching step:

obtaining a second standard value within a second range by analyzing the parameters related to the sample test item of the wafers in the high yield group;

performing a second comparison step to compare the parameters of sample test item of each residual lot in the low yield group with the second standard value and delete lot numbers of residual lots with parameters related to the sample test item within the second range;

determining a second amount of residual lots in the low yield group after the second comparison step; and

in response to the second amount of residual lots in the low yield group not equaling to zero, performing a second searching step to determine which item of the in-line QC items and the manufacturing machine items is related to the sample test item of each residual lot from the low yield group in the database.

3. The method of claim 2 wherein further steps are needed when the in-line QC item is determined to be related to the sample test item in the second searching step:

obtaining a third standard value within a third range by analyzing the parameters related to the in-line QC item of the wafers in the high yield group;

performing a third comparison step to compare the parameters of in-line QC item of each residual lot in the low yield group with the third standard value and delete lot numbers of residual lots with the parameters related to the in-line QC item within the third range;

determining a third amount of residual lots in the low yield group after the third comparison step; and

in response to the third amount of residual lots in the low yield group not equaling to zero, performing a third searching step to determine the process step item related to the in-line QC item of each residual lot in the low yield group in the database.

4. The method of claim 3 wherein further steps are needed when the process step item is determined to be related to the in-line QC item in the third searching step:

searching for manufacturing machines utilized for the production of the wafers in the high yield group at the process step;

searching for manufacturing machines utilized for the production of the residual lots of wafers in the low yield group at the process step; and

performing a determining process to determine manufacturing machines utilized for producing more wafers included in the residual lots in the low yield group than wafers in the high yield group.

5. The method of claim 4 wherein the determining process is performed by using a commonality analyzing method to determine manufacturing machines utilized for producing more wafers included in the residual lots in the low yield group than wafers in the high yield group.

6. The method of claim 1 wherein further steps are needed when the in-line QC item is determined to be related to the wafer test item in the first searching step:

obtaining the third standard value within the third range by analyzing the parameters related to the in-line QC item of the wafers in the high yield group;

performing the third comparison step to compare the parameters of in-line QC item of each residual lot in the low yield group with the third standard value and delete lot numbers of residual lots with the parameters related to the in-line QC item within the third range;

determining the third amount of residual lots in the low yield group after the third comparison step; and

in response to the third amount of residual lots in the low yield group not equaling to zero, performing the third searching step to determine which item of the process step items is related to the in-line QC item of each residual lot in the low yield group in the database.

7. The method of claim 6 wherein further steps are needed when the process step item is determined to be related to the in-line QC item in the third searching step:

searching for manufacturing machines utilized for the production of the wafers in the high yield group at the process step;

searching for manufacturing machines utilized for the production of the residual lots of wafers in the low yield group at the process step; and

performing the determining process to determine manufacturing machines utilized for producing more wafers included in the residual lots in the low yield group than wafers in the high yield group.

8. The method of claim 7 wherein the determining process is performed by using the commonality analyzing method to determine manufacturing machines utilized for producing more wafers included in the residual lots in the low yield group than wafers in the high yield group.

9. The method of claim 1 wherein further steps are needed when the process step item is determined to be related to the wafer test item in the first searching step:

searching for manufacturing machines utilized for the production of the wafers in the high yield group at the process step;

searching for manufacturing machines utilized for the production of the residual lots of wafers in the low yield group at the process step; and

performing the determining process to determine manufacturing machines utilized for producing more wafers included in the residual lots in the low yield group than wafers in the high yield group.

10. The method of claim 9 wherein the determining process is performed by using the commonality analyzing method to determine manufacturing machines utilized for producing more wafers included in the residual lots in the low yield group than wafers in the high yield group.

11. The method of claim 1 wherein further steps are needed when the first amount of residual lots in the low yield group is determined not to be zero:

determining defects on wafers in the residual lots in the low yield group and recording lot numbers of lots comprising wafers with defects;

making a distribution chart of defects in a plurality of layers on each wafer with defects in each lot;

making a distribution chart of the wafer test parameters of each wafer with defects;

comparing the distribution chart of defects for the plurality of layers with the distribution chart of wafer test parameters of each wafer with defects to obtain an overlapping ratio of the distribution chart of defects in the plurality of layers to the distribution chart of wafer test parameters of each wafer with defects and finding out at least one target layer with a high overlapping ratio; and

searching the database for the process step item related to the target layer.

12. The method of claim 11 wherein further steps are needed when the target layer is determined to be related to the process step item by searching the database:

searching for manufacturing machines utilized for the production of the wafers in the high yield group at the process step;

searching for manufacturing machines utilized for the production of the residual lots of wafers in the low yield group at the process step; and

performing the determining process to determine manufacturing machines utilized for producing more wafers included in the residual lots in the low yield group than wafers in the high yield group.

13. The method of claim 12 wherein the determining process is performed by using the commonality analyzing method to determine manufacturing machines utilized for producing more wafers included in the residual lots in the low yield group than wafers in the high yield group.

14. The method of claim 11 wherein the method for analyzing wafer test parameters of a plurality of lots of wafers further comprises the following step of:

obtaining a fourth standard value as a control specification by statistically analyzing the defect counts in the target layer.

15. The method of claim 14 wherein the method for analyzing wafer test parameters of a plurality of lots of wafers further comprises the following step of:

predicting the yield of following products which process to the target layer based on the fourth standard value.

16. The method of claim 1 wherein further steps are needed when the first amount of residual lots in the low yield group is determined not to be zero:

determining defects on wafers in the residual lots in the low yield group and recording lot numbers of lots comprising wafers with defects;

making a distribution chart of defects in each layer on each wafer with defects in each lot;

calculating the defects in each layer on each wafer with defects in each lot;

analyzing a distribution chart of the wafer test parameters of each wafer with defects;

comparing the distribution chart of defects in each layer with the distribution chart of wafer test parameters of each wafer with defects to obtain an overlapping ratio of the distribution chart of defects in each layer to the distribution chart of wafer test parameters of each wafer with defects;

calculating a defect ratio of the number of defects in each layer on each wafer to the number of dies with wafer test parameters not within the first range;

determining the overlapping ratio;

in response to the overlapping ratio larger than or equal to a fifth standard value, marking the layer as a first defective layer;

determining the defect ratio;

in response to the defect ratio larger than or equal to a sixth standard value, marking the layer as a second defective layer;

searching for lot numbers of lots with wafers comprising at least one of either the first defective layer or the second defective layer; and

searching the database for the process step item related to either the first defective layer or the second defective layer.

17. The method of claim 16 wherein the following steps are needed when the process step item is determined to be related to either the first defective layer or the second defective layer by searching the database:

searching for manufacturing machines utilized for the production of the wafers in the high yield group at the process step;

searching for manufacturing machines utilized for the production of lots of wafers comprising at least one of either the first defective layer or the second defective layer at the process step; and

performing a determining process to determine manufacturing machines utilized for producing more wafers comprising at least one of the first defective layer and the second defective layer than wafers in the high yield group.

18. The method of claim 17 wherein the determining process is performed by using the commonality analyzing method to determine manufacturing machines utilized for producing more wafers comprising at least one of the first defective layer and the second defective layer than wafers in the high yield group.

19. The method of claim 16 wherein the method for analyzing wafer test parameters of a plurality of lots of wafers further comprises the following step of:

statistically analyzing the number of defects in at least one of the first defective layer and the second defective layer to obtain a seventh standard value utilized for defect control specification of at least one of the first defective layer and the second defective layer.

20. The method of claim 19 wherein the method for analyzing wafer test parameters of a plurality of lots of wafers further comprises the following step of:

predicting the yield of following products which process to the first defective layer or the second defective layer based on the seventh standard value.

21. A method for analyzing wafer test parameters of a plurality of lots of wafers, each lot of the wafers comprising a lot number, each wafer of each lot comprising at least one wafer test parameter generated by performing at least one wafer test item stored in a database, the wafer test item comprising a plurality of electrical tests performed on each die of each wafer, the wafer test parameters comprising statistic results of the electrical tests, parameters related to at least one sample test item, one in-line quality control (QC) item and one process step item related to the wafer test item being stored in the database, the method comprising:

dividing the lots of wafers into at least a high yield group and a low yield group based on yield of the lots;

obtaining a first standard value within a first range by analyzing the wafer test parameters of the wafers in the high yield group;

performing a first comparison step to compare each wafer test parameter of each lot in the low yield group with the first standard value and delete lot numbers of lots with wafer test parameters within the first range;

determining a first amount of residual lots in the low yield group after the first comparison step; and

in response to the first amount of residual lots in the low yield group not equaling to zero, performing following steps;

searching for parameters of the electrical tests performed on each die of each wafer in the low yield group to define dies failing in the electrical tests as target dies and obtain a distribution chart of target dies of each wafer;

comparing the distribution chart of target dies of each wafer with a distribution chart of the wafer test parameters of the corresponding wafer to obtain an overlapping ratio;

marking wafers with the overlapping ratio greater than an second standard value as target wafers;

selecting lot numbers of lots comprising an amount of target wafers greater than a third standard value; and

determining which item of the sample test items and the process step items is related to the wafer test item of each residual lot in the low yield group in the database.

22. The method of claim 21 wherein further steps are needed when the sample test item is determined to be related to the wafer test item in the first searching step:

obtaining a fourth standard value within a second range by analyzing the parameters related to the sample test item of the wafers in the high yield group;

performing a second comparison step to compare the parameters of sample test item of each residual lot in the low yield group with the fourth standard value and delete lot numbers of residual lots with parameters related to the sample test item within the second range;

determining a second amount of residual lots in the low yield group after the second comparison step; and

in response to the second amount of residual lots in the low yield group not equaling to zero, performing a second searching step to determine which item of the process step items is related to the sample test item of each residual lot in the low yield group in the database.

23. The method of claim 22 wherein further steps are needed when the process step item is determined to be related to the sample test item in the second searching step:

searching for manufacturing machines utilized for the production of the wafers in the high yield group at the process step;

searching for manufacturing machines utilized for the production of the residual lots of wafers in the low yield group at the process step; and

performing a determining process to determine manufacturing machines utilized for producing more wafers included in the residual lots in the low yield group than wafers in the high yield group.

24. The method of claim 23 wherein the determining process is performed by using a commonality analyzing method to determine manufacturing machines utilized for producing more wafers included in the residual lots in the low yield group than wafers in the high yield group.

25. The method of claim 21 wherein further steps are needed when the process step item is determined to be related to the wafer test item in the first searching step:

searching for manufacturing machines utilized for the production of the wafers in the high yield group at the process step;

searching for manufacturing machines utilized for the production of the residual lots of wafers in the low yield group at the process step; and

performing the determining process to determine manufacturing machines utilized for producing more wafers included in the residual lots in the low yield group than wafers in the high yield group.

26. The method of claim 25 wherein the determining process is performed by using the commonality analyzing method to determine manufacturing machines utilized for producing more wafers included in the residual lots in the low yield group than wafers in the high yield group.

27. The method of claim 21 wherein further steps are needed when the first amount of residual lots in the low yield group is determined not to be zero:

determining defects on wafers in the residual lots in the low yield group and recording lot numbers of lots comprising wafers with defects;

making a distribution chart of defects in a plurality of layers on each wafer with defects in each lot;

making the distribution chart of the wafer test parameters of each wafer with defects;

comparing the distribution chart of defects for the plurality of layers with the distribution chart of wafer test parameters of each wafer with defects to obtain an overlapping ratio of the distribution chart of defects in the plurality of layers to the distribution chart of wafer test parameters of each wafer with defects and finding out at least one target layer with a high overlapping ratio; and

searching the database for the process step item related to the target layer.

28. The method of claim 27 wherein further steps are needed when the target layer is determined to be related to the process step item by searching the database:

searching for manufacturing machines utilized for the production of the wafers in the high yield group at the process step;

searching for manufacturing machines utilized for the production of the residual lots of wafers in the low yield group at the process step; and

performing the determining process to determine manufacturing machines utilized for producing more wafers included in the residual lots in the low yield group than wafers in the high yield group.

29. The method of claim 28 wherein the determining process is performed by using the commonality analyzing method to determine manufacturing machines utilized for producing more wafers included in the residual lots in the low yield group than wafers in the high yield group.

30. The method of claim 27 wherein the method for analyzing wafer test parameters of a plurality of lots of wafers further comprises the following step of:

obtaining a fourth standard value as defect control specification by statistically analyzing the defects in the target layer.

31. The method of claim 30 wherein the method for analyzing wafer test parameters of a plurality of lots of wafers further comprises the following step of:

predicting the yield of following products which process to the target layer based on the fourth standard value.

32. The method of claim 21 wherein further steps are needed when the first amount of residual lots in the low yield group is determined not to be zero:

determining defects on wafers in the residual lots in the low yield group and recording lot numbers of lots comprising wafers with defects;

making a distribution chart of defects in each layer on each wafer with defects in each lot;

calculating the defects in each layer on each wafer with defects in each lot;

analyzing a distribution chart of the wafer test parameters of each wafer with defects;

comparing the distribution chart of defects in each layer with the distribution chart of wafer test parameters of each wafer with defects to obtain an overlapping ratio of the distribution chart of defects in each layer to the distribution chart of wafer test parameters of each wafer with defects;

calculating a defect ratio of the number of defects in each layer on each wafer to the number of dies with wafer test parameters not within the first range;

determining the overlapping ratio;

in response to the overlapping ratio larger than or equal to a fifth standard value, marking the layer as a first defective layer;

determining the defect ratio;

in response to the defect ratio larger than or equal to a sixth standard value, marking the layer as a second defective layer;

searching for lot numbers of lots with wafers comprising at least one of either the first defective layer or the second defective layer; and

searching the database for the process step item related to either the first defective layer or the second defective layer.

33. The method of claim 32 wherein the following steps are needed when the process step item is determined to be related to either the first defective layer or the second defective layer by searching the database:

searching for manufacturing machines utilized for the production of the wafers in the high yield group at the process step;

searching for manufacturing machines utilized for the production of lots of wafers comprising at least one of either the first defective layer or the second defective layer at the process step; and

performing a determining process to determine manufacturing machines utilized for producing more wafers comprising at least one of the first defective layer and the second defective layer than wafers in the high yield group.

34. The method of claim 33 wherein the determining process is performed by using the commonality analyzing method to determine manufacturing machines utilized for producing more wafers comprising at least one of the first defective layer and the second defective layer than wafers in the high yield group.

35. The method of claim 32 wherein the method for analyzing wafer test parameters of a plurality of lots of wafers further comprises the following step of:

statistically analyzing the number of defects in at least one of the first defective layer and the second defective layer to obtain a seventh standard value utilized for defect control specification of at least one of the first defective layer and the second defective layer.

36. The method of claim 35 wherein the method for analyzing wafer test parameters of a plurality of lots of wafers further comprises the following step of:

predicting yield of following products which process to either one of the first defective layer or the second defective layer based on the seventh standard value.