Methods of using adaptive sampling techniques based upon categorization of process variations, and system for performing same

• US 6,859,746 B1
• Filed: 05/01/2003
• Issued: 02/22/2005
• Est. Priority Date: 05/01/2003
• Status: Active Grant

• Current Assignee: Advanced Micro Devices, Inc.
• Original Assignee: Advanced Micro Devices, Inc.
• Inventors: Stirton, James Broc
• Primary Examiner(s): Bui, Bryan
• Assistant Examiner(s): Washburn, Douglas N
• Application Number:
  US10/427,621
• Time in Patent Office: 663 Days
• Field of Search: 738/658, 438/14, 438/17, 700/1, 700/90, 700/95, 700/108, 700/109, 700/121, 702/33, 702/57, 702/81, 702/83, 702/84, 702/85, 702/127, 702/182, 702/184, 702/121
• US Class Current: 702/83
• CPC Class Codes: G03F 7/70508 Data handling in all parts of the microlithographic apparatus, e.g. handling pattern data for addressable masks or data transfer to or from different components within the exposure apparatus
• CPC Class Codes: G03F 7/70625 Dimensions, e.g. line width, critical dimension [CD], profile, sidewall angle or edge roughness
• CPC Class Codes: G03F 7/70633 Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
• CPC Class Codes: G05B 19/41865 characterised by job scheduling, process planning, material flow
• CPC Class Codes: G05B 2219/31292 Data in categories, each with a priority factor
• CPC Class Codes: G05B 2219/31485 Verify and update all related data in relational database
• CPC Class Codes: G05B 2219/45031 Manufacturing semiconductor wafers
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

Methods of using adaptive sampling techniques based upon categorization of process variations, and a system for performing same are disclosed. In one illustrative embodiment, the method comprises acquiring metrology data regarding at least one process operation performed on a plurality of substrates in accordance with an initial metrology sampling plan, providing the acquired metrology dam to a controller that identifies process variations in the at least one process operation based upon the acquired metrology data and further identifies a plurality of categories of the process variations. The method further comprises creating, using the controller, a modified metrology sampling plan based upon a relative weighing of the identified categories of the process variations, wherein the modified metrology sampling plan differs from the initial metrology sampling plan in at least one aspect, and acquiring metrology data from at least one subsequently processed wafer in accordance with the modified neology sampling plan.

Claims

1. A method, comprising:

acquiring metrology data regarding at least one process operation performed on a plurality of substrates in accordance with an initial metrology sampling plan;

providing said acquired metrology data to a controller that identifies process variations in said at least one process operation based upon said acquired metrology data and further identifies a plurality of categories of said process variations;

creating, using said controller, a modified metrology sampling plan based upon a relative weighting of said identified categories of said process variations, said modified metrology sampling plan differing from said initial metrology sampling plan in at least one aspect; and

acquiring metrology data from at least one subsequently processed wafer in accordance with said modified metrology sampling plan.

2. The method of claim 1, wherein said initial metrology sampling plan involves obtaining metrology measurements from at least one of a fixed number of metrology sites across a wafer, a plurality of metrology sites arranged in a specified pattern, a fixed number of metrology sites within an exposure field of a stepper exposure process, and a fixed number of wafers within a lot of said wafers.

3. The method of claim 1, wherein said controller is resident on a stanch alone metrology tool.

4. The method of claim 1, wherein said controller is resident on a process tool adapted to perform said at least one process operation.

5. The method of claim 1, wherein said controller is a stand-alone computer.

6. The method of claim 1, wherein said plurality of categories of said process variations is comprised of at least one of across wafer process variations, wafer-to-wafer Process variations, lot-to-lot process variations and within exposure field process variations.

7. The method of claim 1, wherein said at least one aspect by which said modified metrology sampling plan varies from said initial metrology sampling plan comprises at least one of a number of metrology measurements, a pattern of metrology measurement sites, and a number of wafers measured within a lot of subsequently process wafers.

8. The method of claim 1, wherein said modified metrology sampling plan includes increasing an amount of across-wafer metrology data acquired relative to an amount of across-wafer metrology data acquired bed upon said initial metrology sampling plan due to a higher relative weighting of across-wafer process variations as compared to at least one of wafer-to-wafer process variations and within exposure field process variations determined from said metrology data acquired in accordance with said initial metrology sampling plan.

9. The method of claim 1, wherein said modified metrology sampling plan includes increasing an amount of wafer-to-wafer metrology data acquired relative to an amount of wafer-to-wafer rheology data acquired based upon said initial metrology sampling plan due to a higher relative weighting of wafer-to-wafer process variations as compared to at least one of across-wafer process variations and within exposure field process variations determined from said metrology data acquired in accordance with said initial metrology sampling plan.

10. The method of claim 1, wherein said modified metrology, sampling plan includes increasing an amount of within exposure field metrology data relative to an amount of within exposure field metrology data acquired based upon said initial metrology sampling plan due to a higher relative weighting of with within exposure field process variations as compared to at least one of wafer-to-wafer process variations and across-wafer process variations determined from said metrology data acquired in accordance with said initial metrology sampling plan.

11. The method of claim 1, wherein said at least one process operation is comprised of at least one of a stepper exposure process, a deposition process, an ion implant process, an etching process and a heating process.

12. The method of claim 1, further comprising, after acquiring data in accordance with said modified metrology sampling plan, periodically acquiring additional metrology data in accordance with said initial metrology sampling plan.

13. A method, comprising:

acquiring metrology data regarding at least one process operation performed on a plurality of substrates in accordance with an initial metrology sampling plan;

providing said a metrology data to a controller that identifies process variations in said at least one process operation based upon said acquired metrology data and further identifies a plurality of categories of said process variations;

creating, using said controller, a modified metrology sampling plan based upon a relative weighting of said identified categories of said process variations, said modified metrology sampling plan involving acquiring an enhanced amount of metrology data relevant to one of said identified categories having a higher relative weighting; and

acquiring metrology data from at least one subsequently processed wafer in accordance with said modified metrology sampling plan.

14. The method of claim 13, wherein said initial metrology sampling plan involves obtaining metrology measurements from at least one of a fixed number of metrology sites across a wafer, a plurality of metrology sites arranged in a specified pattern, a fixed number of metrology sites within an exposure field of a stepper exposure process, and a fixed number of wafers within a lot of said wafers.

15. The method of claim 13, wherein said controller is resident on a standalone metrology tool.

16. The method of claim 13, wherein said controller is resident on a process tool adapted to perform said at least one process operation.

17. The method of claim 13, wherein said controller is a stand-alone computer.

18. The method of claim 13, wherein said plurality of categories of said process variations is comprised of at least one of across-wafer process variations, wafer-to-wafer process variations, lot-to-lot process variations and within exposure field process variations.

19. The method of claim 13, wherein said at least one a by which said modified metrology sampling plan varies from said initial metrology sampling plan comprises at least one of a number of metrology measurements, a pattern of metrology measurement sites, and a number of wafers measured within a lot of subsequently process wafers.

20. The method of claim 13, wherein said modified metrology sampling plan involves acquiring an enhanced amount of metrology data relevant to across-wafer process variations.

21. The method of claim 13, wherein said modified metrology sampling plan involves acquiring an enhanced amount of wafer metrology data relevant to wafer-to-wafer process variations.

22. The method of claim 13, wherein said modified metrology sampling plan involves acquiring an enhanced amount of metrology data relevant to within exposure field process variations.

23. The method of claim 13, wherein said at least one process operation is comprised of a least one of a stepper exposure process, a deposition process, an ion implant process, an etching process and a heating process.

24. The method of claim 13, further comprising, after acquiring data in accordance with said modified metrology sampling plan, periodically acquiring additional metrology data in accordance with said initial metrology sampling plan.