Process and apparatus for detecting aberrations in production process operations

• US 4,847,792 A
• Filed: 05/04/1987
• Issued: 07/11/1989
• Est. Priority Date: 05/04/1987
• Status: Expired due to Term

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Ratliff, Charles, Barna, Gabriel G.
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): Ramirez, Ellis B.
• Application Number:
  US07/046,497
• Time in Patent Office: 799 Days
• Field of Search: 364/550-552, 364/559, 364/468, 364/500, 156/345, 156/626-627, 204/192.33, 219/121 PD, 437/8
• US Class Current: 702/182
• CPC Class Codes: H01J 37/32935 Monitoring and controlling tubes by information coming from the object and/or discharge

Abstract

An apparatus and process for detecting aberrations in production process operations is provided. In one embodiment, operations of a plasma etch reactor (10) are monitored to detect aberrations in etching operations. A reference end-point trace (EPT) is defined (50), regions are defined in the reference EPT (52) and characteristics and tolerances for each region are defined (54). The etcher is run (56) and an actual EPT is obtained from the running of the etcher. The actual EPT is analyzed (58) by comparing characteristics of the regions of the actual EPT with characteristics of corresponding regions of the reference EPT. If the characteristics of the actual EPT exceed those of the reference EPT by predefined tolerances (62) a signal is generated (68). The system also checks for aberrations which are manifested by predefined EPT characteristics and signals when those are detected.

Claims

1. A method of obtaining process operation information from a plasma reactor, said reactor being capable of effecting a reaction with at least a particular material from a slice, which slice includes said particular material and on which semiconductor components are being at least partially formed, there being a sensor associated with said reactor and capable of producing an electrical signal having a varying amplitude proportional to the varying intensity of a reaction of said particular material in said reactor as said reaction progresses with time, a start and an end of said reaction each being indicated by said electrical signal passing through a threshold amplitude and varying intensities of said reaction between said start and end being indicated by varying amplitudes of said electrical signal different from said threshold amplitude, said method comprising:

A. selecting a series of reference varying amplitudes to define a reference continuously variable signal curve indicative of observed intensities of a desired reaction of said particular material in said plasma reactor from at least said start to at least said end;

B. conducting an actual reaction of said particular material in said plasma reactor from at least said start to at least said end;

C. acquiring actual varying amplitudes of said electrical signal, which forms an actual continuously variable signal curve, between said start and end during said conducting said reaction;

D. comparing said reference varying amplitudes and said actual varying amplitudes; and

E. generating an indicator signal upon said reference and actual amplitudes differing from one another by a particular amount to indicate an aberration in said actual reaction compared to said desired reaction.

2. The method of claim 1, further including:

dividing said reference curve into a plurality of regions;

dividing the actual curve into a plurality of regions; and

comparing characteristics of at least one region of the actual curve with corresponding characteristics of a corresponding region of the reference curve.

3. The method of claim 2, wherein the actual curve is divided into a plurality of regions as a function of time from the start of the etch as indicated by the actual curve.

4. The method of claim 2, further including:

generating a predetermined signal if the comparison of characteristics of at least one region of the actual curve with the characteristics of a corresponding region of the reference curve indicate a deviation between such characteristics that exceeds a predetermined value.

5. The method of claim 2, wherein the characteristics of one region of the actual curve which are compared with the characteristics of a corresponding region of the reference curve include at least one of:

the slope of the curve in the region;

the amplitude of the curve in the region;

the deviation of the curve in the region from a straight line;

the integral of the area of the region; and

the sum of the squares of deviation from the reference curve in the region.

6. The method of claim 2, further including:

determining whether a deviation between a characteristic of the actual trace and a corresponding characteristic of the reference trace exceeds predefined values;

attributing such deviation to at least one predefined cause; and

generating a cause signal identifying said at least one predefined cause to which the deviation has been attributed.

7. The method of claim 2, wherein the actual curve of the plasma etch reactor is acquired by monitoring a reaction species of the etch operation.

8. The method of claim 7, wherein said reaction species monitored by the end-point trace is carbon monoxide.

9. A method of monitoring operations in process equipment which carries out a predetermined etched plasma process, which process is first monitored by detector apparatus that provides an actual continuously variable signal curve corresponding to the progress of the process, and wherein the reference continuously variable signal curve can be defined, which reference continuously variable signal curve corresponds to a predefined acceptable operation of the predetermined process, the method comprising:

defining a reference continuously variable signal curve for the predetermined process;

defining a plurality of regions in said reference continuously variable signal curve;

defining characteristics for at least one region of said reference continuously variable signal curve;

conducting said predetermined process;

acquiring from the detector apparatus an actual continuously variable signal curve corresponding to the progress of the process conducted from a start to and end of the process;

dividing the actual continuously variable signal curve acquired into regions;

comparing characteristics of at least one of the regions of the actual continuously variable signal curve with the characteristics of a corresponding region in the reference continuously variable signal curve; and

generating an indicator signal if a characteristic of one of the regions of the actual continuously variable signal curve exceeds by a predetermined limit a corresponding characteristic of a region of the reference continuously variable signal curve.

10. The method of claim 9, further including:

attributing at least one predefined cause to a deviation between a characteristic of the actual continuously variable signal curve and a corresponding characteristic of the reference continually variable signal curve exceeding a predefined value; and

generating a cause signal identifying said at least one predefined cause to which the deviation has been attributed.

11. The method of claim 9, wherein said continuously variable signal curve is generated by a continuously variable signal of voltage which varies with time.

12. The method of claim 11, wherein the beginning of said predetermined process is signified approximately when the voltage of said continuously variable signal crosses a predefined threshold value.

13. The method of claim 9, wherein the predetermined process includes a plasma etch process.

14. The process of claim 13, wherein the reference continuously variable signal curve includes a reference trace curve for the plasma etch process and the actual continuously variable signal curve includes an actual trace for the plasma etch process.

15. The method of detecting aberrations in semiconductor manufacturing operations, comprising:

defining a reference trace for a predetermined etch process;

defining regions in the reference trace;

defining characteristics for at least one region of the reference trace;

conducting the predetermined etch process on a semiconductor device;

acquiring an actual trace for the etch of the semiconductor device from a start to an end of the operation;

dividing the actual trace into regions corresponding to the predefined regions of the reference trace;

comparing characteristics of at least one region of the actual trace with corresponding characteristics of the corresponding region of the reference trace; and

generating an indicator signal if characteristics of the at least one region of the actual trace vary beyond predefined limits corresponding characteristics of the corresponding region of the reference trace.

16. The method of claim 15, wherein the actual end-point trace is sampled at predetermined intervals during the etch process.

17. The method of claim 15, wherein the reference end-point trace is divided into at least three regions.

18. The method of claim 15, wherein there corresponds a region in the reference end-point trace for at least one layer of material to be etched from the semiconductor device.

19. The method of claim 15, wherein the characteristics of one region of the reference end-point trace which are compared with the characteristics of the corresponding region of the actual end-point trace include at least one of:

the slope of the end-point trace in the region;

the amplitude of the end-point trace in the region;

the deviation of the end-point trace in the region from a straight line;

the integral of the area of the region; and

the sum of the squares of deviation from the reference curve in the region.

20. The method of claim 15, further including:

determining whether a deviation between at least one characteristic of the actual trace and at least one corresponding characteristic of the reference trace exceeds a predefined value for each characteristic;

attributing such deviation to at least one, predefined cause; and

generating a cause signal identifying said at least one predefined cause to which the deviation has been attributed.

21. The method of claim 15, wherein the regions of the reference end-point trace are defined as a function of time from the initiation of the etch process.

22. The method of claim 21, wherein said step of dividing the actual end-point trace into regions corresponding to the predefined regions of the reference end-point trace is conducted by dividing the actual end-point trace into regions as a function of time.

23. A method of detecting aberrations in a plasma process of semiconductor manufacturing operations, comprising:

defining a reference trace for said plasma process;

conducting the plasma process on a semiconductor device;

acquiring an actual trace for the process of the semiconductor device from a start to and end;

dividing the reference trace into predefined regions;

dividing the actual trace into regions corresponding to the predefined regions of the reference trace;

comparing characteristics of regions of the actual trace with corresponding characteristics of corresponding regions of the reference trace; and

generating an indicator signal if characteristics of the regions of the actual trace vary beyond predefined limits from corresponding characteristics of corresponding regions of the reference trace.

24. The method of claim 23, wherein said step of dividing the actual trace into regions includes dividing the actual trace into regions with at least a portion of the start and end of the regions being determined as a function of time from a defined start of the actual trace.

25. The method of claim 24, wherein said defined beginning of the actual trace includes a point in time when the actual trace exceeds a predetermined threshold value.

26. A method of obtaining process operation information form a plasma reactor, said reactor being capable of effecting a reaction with at least a particular material from a slice, which slice includes said particular material and on which semiconductor components are being at lease partially formed, there being a sensor associated with said reactor and capable of producing an electrical signal having a varying amplitude proportional to the varying intensities of a reaction of said particular material in said reactor as said reaction progresses with time, a start and an end of said reaction each being indicated by said electrical signal of a threshold amplitude and varying intensities of said reaction between said start and end being indicated by varying amplitudes of said electrical signal different from said threshold amplitude, said method comprising:

A. selecting a series of reference varying amplitudes to define a reference continuously variable signal curve indicative of intensities of at least a certain reaction specie of a desired reaction of said particular material in said plasma reactor from at least said start to at least said end;

B. conducting an actual reaction of said particular material to produce time varying quantities of said certain reaction specie in said plasma reactor from the start of said reaction through the end of said reaction;

C. acquiring actual varying amplitudes of said electrical signal to form an actual continuously variable signal curve indicating the time varying quantities of said certain reaction specie between said start and end during said conducting said reaction;

D. dividing each of said reference and actual curves into at least one region between said start and end;

E. defining at least the same one characteristic for each of said at least one regions of each of said reference and actual curves;

F. comparing said at least one same characteristic of said at least one regions of said reference and actual curves with one another; and

G. generating an indicator signal indicating the results of the comparison of said at least one same characteristic of said at least one regions of said reference and actual curves with one another.

27. A method of obtaining process information during production of semiconductor devices by a plasma reaction comprising:

A. conducting said reaction from at least a start to at least an end;

B. acquiring actual continuous data from said reaction that corresponds to the observed progress of said reaction from said start to said end; and

C. comparing said actual continuous data to reference continuous data to obtain said information.

28. The method of claim 27 in which said conducting includes conducting an etch reaction, and said acquiring actual data includes monitoring a reaction specie of said etch reaction.

29. The method of claim 27 including generating a predetermined signal upon said comparing indicating a deviation between said reference and actual data that exceeds a predetermined value.

30. The method of claim 27 in which said acquiring includes sampling said actual data at predetermine intervals during the etch process.

31. The method of claim 27 in which said comparing includes:

A. determining whether a deviation between said reference and actual data exceeds a predefined value;

B. attributing at least one cause to said deviation; and

C. generating a cause signal identifying said at least one cause to which said deviation has been attributed.

32. The method of claim 27 in which said acquiring actual data includes generating an actual data signal of voltage that varies in amplitude with time according to observed intensities of said reaction.

33. The method of claim 32 including defining said start approximately when said actual data signal voltage crosses a predetermined threshold value.

34. The method of claim 27 including:

A. dividing the reference data into plural regions;

B. dividing the actual data into plural regions; and

C. comparing characteristics of at least one region of the actual data with corresponding characteristics of a corresponding region of the reference data.

35. The method of claim 34 in which said monitoring includes monitoring a reaction specie of carbon monoxide.

36. The method of claim 34 including dividing said actual data into plural regions as a function of time from the start of said reaction.

37. The method of claim 34 in which said comparing characteristics includes comparing at least one of:

A. the slope of the data in a region;

B. the amplitude of the data in a region;

C. the deviation of the data in the region from a straight line;

D. the integral of the area of the region; and

E. the sum of the squares of deviation from the reference curve in the region.

38. The method of claim 34 in which said dividing the reference data includes dividing the reference data into plural regions as a function of time from the initiation of said reaction.

39. The method of claim 34 in which said dividing the reference data includes dividing the reference data into at least three regions.

40. The method of claim 34 in which said dividing the reference data includes dividing the reference data into a region for at least one layer of material to be etched from the semiconductor device.

41. The method of claim 34 in which said dividing said actual data into plural regions includes determining at least a portion of a start and end of said regions as a function of time from said start.