Electrical field alignment vernier

• US 20030186133A1
• Filed: 04/01/2002
• Published: 10/02/2003
• Est. Priority Date: 04/01/2002
• Status: Active Grant

• Current Assignee: Micrel Incorporated (Microchip Technology Incorporated)
• Original Assignee: Micrel Incorporated (Microchip Technology Incorporated)
• Inventors: Rumsey, Robert W.
• Granted Patent: US 6,762,432 B2
• Time in Patent Office: Days
• US Class Current: 430/5
• 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: G03F 7/70658 Electrical testing

Abstract

A test structure pattern includes a first comb having a first set of tines, and a second comb having a second set of tines of the same width and spacing as the first set of tines. When the test structure pattern is stepped between fields on a wafer, the first comb and the second comb at least partially overlap on photoresist over a scribe lane between the fields. When the photoresist is developed, the overlap of the first comb and the second comb generates a metal comb. Electrical continuity is checked for the metal tines of the metal comb to determine the misalignment of the fields.

Claims

1. A test structure pattern, comprising:

a first scribe comprising a first comb, the first comb comprising a first plurality of tines;

a pad coupled in parallel to the first plurality of tines;

a second scribe comprising a second comb, the second comb comprising a second plurality of tines of same widths and spacing as the first plurality of tines; and

a plurality of pads coupled individually to the second plurality of tines.

2. The test structure pattern of claim 1, wherein the test structure pattern is stepped between fields on a wafer and the first scribe and the second scribe at least partially overlap on a scribe lane between the fields so the first comb and the second comb at least partially overlap.

3. The test structure pattern of claim 1, wherein the first plurality of tines and the second plurality of tines each comprises tines of incrementing width.

4. The test structure pattern of claim 1, wherein the first plurality of tines are spaced apart at least by the width of the largest tine of the first plurality of tines, and the second plurality of tines are spaced apart at least by the width of the largest tine of the second plurality of tines

5. The test structure pattern of claim 1, further comprising a plurality of lines that couple the second plurality of tines to the plurality of pads, the plurality of lines each having the width of at least the width of the tine it is coupled to.

6. The test structure pattern of claim 1, wherein the width of one of the first plurality of tines is equal to a critical dimension, and the width of one of the second plurality of tines is equal to the critical dimension.

7. The test structure pattern of claim 1, further comprising a field region, wherein the first scribe is located along a first edge of the field region and the second scribe is located along an opposite edge of the field region.

8. The test structure pattern of claim 1, wherein the first comb and the second comb are opaque patterns.

9. A mask, comprising:

a field region;

a first scribe along the field region, the first scribe comprising a first comb, the first comb comprising a first plurality of tines;

a pad in the field region coupled in parallel to the first plurality of tines;

a second scribe along the field region and opposite the first scribe, the second scribe comprising a second comb, the second comb comprising a second plurality of tines of same widths and spacing as the first plurality of tines; and

a plurality of pads in the field region, the plurality of pads being coupled individually to the second plurality of tines.

10. A method for electrically determining field alignment, comprising:

forming a plurality of test structures on a scribe line between a first field and a second field on a wafer; and

detecting electrical continuity in at least one of the test structures, wherein electrical continuity of each of the test structures indicates a level of alignment of the fields.

11. The method of claim 10, wherein the test structures are metal tines of a metal comb.

12. The method of claim 11, wherein said forming a plurality of test structures comprises:

exposing a first scribe pattern from a mask on a resist over the scribe lane, wherein the first scribe pattern comprises a first comb, the first comb comprising a first plurality of tines;

stepping the mask from the first field to the second field;

exposing a second scribe pattern from the mask on the resist over the scribe lane, wherein the second scribe pattern comprises a second comb, the second comp comprising a second plurality of tines;

developing the resist over the scribe lane; and

etching the scribe lane to form the metal tines.