Apparatus and methods for detecting overlay errors using scatterometry
First Claim
1. A scatterometry mark for determining an overlay error, critical dimension, or profile of the mark, comprising:
- a first plurality of periodic structures on a first layer;
a second plurality of periodic structures on a second layer; and
a third plurality of periodic structures on a third layer that is underneath the first and second layer, wherein the third periodic structures are perpendicular to the first and second structures, and wherein the third periodic structures have one or more characteristics so as to result in a plurality of lower structures beneath the third periodic structures being screened from significantly affecting at least part of a spectrum of a plurality of scattered signals detected from the first and second periodic structures for determining an overlay error, critical dimension, or profile of the first and second periodic structures or at least one of such detected scattered signals.
1 Assignment
0 Petitions
Accused Products
Abstract
Disclosed is a scatterometry mark for determining an overlay error, critical dimension, or profile of the mark. The mark includes a first plurality of periodic structures on a first layer, a second plurality of periodic structures on a second layer, and a third plurality of periodic structures on a third layer that is underneath the first and second layer. The third periodic structures are perpendicular to the first and second structures, and the third periodic structures have one or more characteristics so as to result in a plurality of lower structures beneath the third periodic structures being screened from significantly affecting at least part of a spectrum of a plurality of scattered signals detected from the first and second periodic structures for determining an overlay error, critical dimension, or profile of the first and second periodic structures or at least one of such detected scattered signals.
-
Citations
21 Claims
-
1. A scatterometry mark for determining an overlay error, critical dimension, or profile of the mark, comprising:
-
a first plurality of periodic structures on a first layer; a second plurality of periodic structures on a second layer; and a third plurality of periodic structures on a third layer that is underneath the first and second layer, wherein the third periodic structures are perpendicular to the first and second structures, and wherein the third periodic structures have one or more characteristics so as to result in a plurality of lower structures beneath the third periodic structures being screened from significantly affecting at least part of a spectrum of a plurality of scattered signals detected from the first and second periodic structures for determining an overlay error, critical dimension, or profile of the first and second periodic structures or at least one of such detected scattered signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
- 10. A target structure for measuring an overlay error between a first periodic structure and a second periodic structure both disposed above a third periodic structure, wherein the third periodic structure is oriented in a first direction and the first and second periodic structures are oriented in a second direction, the second direction being substantially orthogonal to the first direction, wherein the third periodic structure is arranged to form a barrier over lower structures beneath the third periodic structures so that such lower structures do not significantly affect scattered radiation from the first and second periodic structures for measuring the overlay error.
-
13. A metrology system for measuring an overlay error, critical dimension (CD), or profile of a target, comprising:
-
a scatterometry module for directing radiation towards a plurality of targets and detecting scattered signals from the targets; and a processor configured to analyze the detected scattered signals to thereby determine an overlay error, critical dimension (CD), or profile of such targets, wherein the targets comprise a first periodic structure and a second periodic structure both disposed above a third periodic structure, wherein the third periodic structure is oriented in a first direction and the first and second periodic structures are oriented in a second direction, the second direction being substantially orthogonal to the first direction, wherein the third periodic structure is arranged to form a barrier over lower structures beneath the third periodic structures so that such lower structures do not significantly affect the scattered signals from the first and second periodic structures and analyzed by the processor. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
-
-
21. A method of determining an overlay error, critical dimension, or profile of a scatterometry target, comprising:
-
providing a scatterometry target having a first plurality of periodic structures on a first layer, a second plurality of periodic structures on a second layer, and a third plurality of periodic structures on a third layer that is underneath the first and second layer, wherein the third periodic structures are perpendicular to the first and second structures and have one or more characteristics such that a scattered signal detected from the first and second periodic structures for determining an overlay error, critical dimension, or profile of the first and second periodic structures is substantially less sensitive to a plurality of lower structures beneath the third periodic structures, as compared with a plurality of scattered signals detected from the first and second periodic targets in the absence of such third structures; using a metrology tool, directing radiation towards the target; using a metrology tool, detecting scattered signals from the target so that the third periodic structures form a barrier over the lower structures beneath the third periodic structures so that such lower structures do not significantly affect the detected scattered signals from the first and second periodic structures; and determining the overlay error, critical dimension, or profile of the first and second periodic structures based on the detected scattered signals.
-
Specification