Apparatus and method for detecting overlay errors using scatterometry
First Claim
1. A method for determining overlay between a plurality of first structures in a first layer of a sample and a plurality of second structures in a second layer of the sample, the method comprising:
- providing targets A, B, C and D that each include a portion of the first and second structures, wherein the target A is designed to have an offset Xa between its first and second structures portions, wherein the target B is designed to have an offset Xb between its first and second structures portions, wherein the target C is designed to have an offset Xc between its first and second structures portions, wherein the target D is designed to have an offset Xd between its first and second structures portions, wherein each of the offsets Xa, Xb, Xc and Xd is different from zero, Xa is an opposite sign and differ from Xb, and Xc is an opposite sign and differs from Xd;
illuminating the targets A, B, C and D with electromagnetic radiation to obtain spectra SA, SB, SC, and SD from targets A, B, C, and D, respectively; and
determining any overlay error between the first structures and the second structures using a linear approximation based on the obtained spectra SA, SB, SC, and SD.
2 Assignments
0 Petitions
Accused Products
Abstract
Disclosed are techniques, apparatus, and targets for determining overlay error between two layers of a sample. In one embodiment, a method for determining overlay between a plurality of first structures in a first layer of a sample and a plurality of second structures in a second layer of the sample is disclosed. Targets A, B, C and D that each include a portion of the first and second structures are provided. Target A is designed to have an offset Xa between its first and second structures portions; target B is designed to have an offset Xb between its first and second structures portions; target C is designed to have an offset Xc between its first and second structures portions; and target D is designed to have an offset Xd between its first and second structures portions. Each of the offsets Xa, Xb, Xc and Xd is preferably different from zero; Xa is an opposite sign and differ from Xb; and Xc is an opposite sign and differs from Xd. The targets A, B, C and D are illuminated with electromagnetic radiation to obtain spectra SA, SB, SC, and SD from targets A, B, C, and D, respectively. Any overlay error between the first structures and the second structures is then determined using a linear approximation based on the obtained spectra SA, SB, SC, and SD.
-
Citations
111 Claims
-
1. A method for determining overlay between a plurality of first structures in a first layer of a sample and a plurality of second structures in a second layer of the sample, the method comprising:
-
providing targets A, B, C and D that each include a portion of the first and second structures, wherein the target A is designed to have an offset Xa between its first and second structures portions, wherein the target B is designed to have an offset Xb between its first and second structures portions, wherein the target C is designed to have an offset Xc between its first and second structures portions, wherein the target D is designed to have an offset Xd between its first and second structures portions, wherein each of the offsets Xa, Xb, Xc and Xd is different from zero, Xa is an opposite sign and differ from Xb, and Xc is an opposite sign and differs from Xd;
illuminating the targets A, B, C and D with electromagnetic radiation to obtain spectra SA, SB, SC, and SD from targets A, B, C, and D, respectively; and
determining any overlay error between the first structures and the second structures using a linear approximation based on the obtained spectra SA, SB, SC, and SD. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 56)
-
-
57. A system for determining overlay between a plurality of first structures in a first layer of a sample and a plurality of second structures in a second layer of the sample, comprising:
-
a scatterometry module for illuminating the targets A, B, C and D with electromagnetic radiation to obtain spectra SA, SB, SC, and SD from targets A, B, C, and D, respectively; and
a processor operable for determining any overlay error between the first structures and the second structures using a linear approximation based on the obtained spectra SA, SB, SC, and SD, wherein targets A, B, C and D each include a portion of the first and second structures, wherein the target A is designed to have an offset Xa between its first and second structures portions, wherein the target B is designed to have an offset Xb between its first and second structures portions, wherein the target C is designed to have an offset Xc between its first and second structures portions, wherein the target D is designed to have an offset Xd between its first and second structures portions, and wherein each of the offsets Xa, Xb, Xc and Xd is different from zero, Xa is an opposite sign and differ from Xb, and Xc is an opposite sign and differs from Xd. - View Dependent Claims (58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, 110)
-
-
111. A target arrangement comprising a first layer having a plurality of first structures and a second layer having a plurality of second structures, the target arrangement further comprising:
-
targets A, B, C and D that each include a portion of the first and second structures, wherein the target A is designed to have an offset Xa between its first and second structures portions, wherein the target B is designed to have an offset Xb between its first and second structures portions, wherein the target C is designed to have an offset Xc between its first and second structures portions, wherein the target D is designed to have an offset Xd between its first and second structures portions, wherein each of the offsets Xa, Xb, Xc and Xd is different from zero, Xa is an opposite sign and differ from Xb, and Xc is an opposite sign and differs from Xd, and wherein the offsets Xa, Xb, Xc, and Xd are selected so that when the targets A, B, C, and D are illuminated with electromagnetic radiation, the targets A, B, C, and D produce a corresponding spectra SA, SB, SC, and SD, respectively which are indicative of any overlay error existing between the first layer and the second layer structures; and
an imaging overlay measurement type target E from which a second overlay error may be determined using imaging overlay metrology.
-
Specification