METHOD OF DETERMINING OVERLAY ERROR AND CONTROL SYSTEM FOR DYNAMIC CONTROL OF RETICLE POSITION

• US 20130201462A1
• Filed: 02/07/2012
• Published: 08/08/2013
• Est. Priority Date: 02/07/2012
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: WANG, Sophia, LEE, Yung-Yao, TSAI, Fei-Gwo, LIU, Heng-Hsin
• Granted Patent: US 9,188,876 B2
• Time in Patent Office: Days
• US Class Current: 355/52
• CPC Class Codes: G03F 1/44 Testing or measuring features, e.g. grid patterns, focus monitors, sawtooth scales or notched scales
• 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

Abstract

A method of determining overlay error. The method includes transferring a pattern from a reticle to a wafer and selecting a first set of data points to measure the positional difference between features on the reticle and features on the wafer. The method also includes determining a second set of data points characteristic of the first set of data points but containing fewer data points. A control system for using the second set of data points to dynamically adjust the position of the reticle.

Claims

1. A method of reducing overlay error comprising:

transferring a pattern of features from a reticle to a wafer;

measuring a positional difference between the pattern on the reticle and the pattern on the wafer at a first set of data points;

determining a second set of data points based on the first set of data points, the second set of data points being a subset of the first set of data points, wherein a position of the second set of data points is indicative of a position of at least one of the first set of data points, and a number of the first set of data points is greater than a number of the second set of data points; and

changing a position of the reticle to minimize the positional difference based on the second set of data points.

2. The method of claim 1, further comprising determining at least one fixed data point.

3. The method of claim 1, wherein determining the second set of data points comprises selecting data points from the first set of data points.

4. The method of claim 1, wherein determining the second set of data points comprises

determining at least one region data point;

determining at least one variable data point, wherein

a summation of a number of the at least one region data point, and a number of the at least one variable data points equals the number of the second set of data points.

5. The method of claim 4, wherein determining a plurality of fixed data points comprises receiving input from a user.

6. The method of claim 1, further comprising determining a plurality of regional boundaries in the pattern of features;

and

positioning at least one of the first set of data points within each of the plurality of regional boundaries.

7. The method of claim 4, further comprising determining a plurality of regional boundaries in the pattern of features to define a plurality of regions;

and

positioning at least one of the first set of data points within each of the plurality of regions, wherein

determining region data points includes selecting one of the at least one of the first set of data points within each of the plurality of regions for each of the plurality of regions.

8. The method of claim 4, wherein determining at least one variable data point includes selecting one or more data points characteristic of the positional difference.

9. The method of claim 4, wherein determining at least one variable data point includes statistical analysis of overlay error measurements.

10. The method of claim 4, wherein determining at least one region data point includes statistical analysis of overlay error measurements.

11. The method of claim 1, wherein transferring the pattern of features from the reticle to the wafer includes using a photolithography process.

12. The method of claim 1, wherein transferring the pattern of features from the reticle to the wafer includes using an electron beam patterning process.

14. The reticle of claim 12, wherein each of the at least one field independently comprises at least one region.

15. The reticle of claim 14, wherein the at least one region measurement position is situated independently in each of the at least one region.

16. The reticle of claim 12, wherein the at least one region measurement position and the at least one variable measurement position are selected based on statistical analysis of overlay error measurements.

13. A reticle comprising:

a light blocking layer having a first surface and a second surface;

a pattern of openings extending from the first surface to second surface;

at least one field, wherein each field comprises;

at least one first opening positioned in the corresponding field in relation to a corresponding at least one fixed measurement position;

at least one second opening positioned in the corresponding field in relation to a corresponding at least one region measurement position; and

at least one third opening positioned in the corresponding field in relation to a corresponding at least one variable measurement position.

17. A feedback control system comprising:

a reticle patterning apparatus configured to transfer a pattern from a reticle to a wafer;

a position measurement tool configured to measure the position of at least one feature of the pattern on the wafer, wherein the at least one position is characteristic of position of a portion of the reticle relative to the wafer; and

a controller configured to receive position data from the position measurement tool and transmit at least one control signal to the reticle patterning apparatus based on the position data.

18. The feedback control system of claim 17, wherein the reticle patterning apparatus is configured to receive the control signals and alter a position of the reticle based on the control signals.

19. The feedback control system of claim 17, wherein the reticle patterning apparatus is a photolithography apparatus.

20. The feedback control system of claim 17, wherein the reticle patterning apparatus is an electron beam patterning apparatus.