Overlay measurement of pitch walk in multiply patterned targets

Patent metadata

Field	Value
Publication number	US-9903813-B2
Application number	US-201514734687-A
Country	US
Kind code	B2
Filing date	Jun 9, 2015
Priority date	Jan 15, 2014
Publication date	Feb 27, 2018
Grant date	Feb 27, 2018

Abstract

Multiply patterned metrology targets and target design methods are provided to enable pitch walk measurements using overlay measurements. Multiply patterned structures having single features or spacers produced simultaneously and sharing a common pitch with the paired features or spacers are used to express pitch walk as a measurable overlay between the structures. For example, targets are provided which comprise a first multiply patterned structure having a single left-hand feature or spacer produced simultaneously and sharing a common pitch with the respective paired features or spacers, and a second multiply patterned structure having a single right-hand feature or spacer produced simultaneously and sharing a common pitch with the respective paired features or spacers.

First claim

What is claimed is:

1. A metrology target, comprising:
a first structure formed from a multiple-patterning process including a first patterning process and a second patterning process, the first structure including one or more feature pairs, wherein a given feature pair of the one or more feature pairs includes a first pair element and a second pair element on a common layer separated by a first pitch, wherein the first structure further includes an isolated first pair element on the common layer formed in a common process with the one or more feature pairs, wherein elements of adjacent feature pairs of the one or more feature pairs are separated by a second pitch equal to the first pitch, wherein the isolated first pair element is separated from an adjacent element of the one or more feature pairs by the second pitch; and
a second structure formed from the multiple-patterning process, the second structure including one or more additional feature pairs, wherein the second structure further includes an isolated second pair element formed in a common process with the one or more additional feature pairs, wherein elements of adjacent feature pairs of the one or more additional feature pairs are separated by the second pitch, wherein the unpaired second pair element is separated from an adjacent element of the one or more additional feature pairs by the second pitch, wherein the one or more feature pairs and the one or more additional feature pairs are formed by the first patterning process generating two or more pre-pattern elements and the second patterning process defining the first pitch based on the two or more pre-pattern elements, wherein an overlay metrology measurement of the first structure and the second structure is indicative of one or more errors in the multiple-patterning process manifested as a deviation of the first pitch with respect to the second pitch.

2. The target of claim 1 , wherein the one or more feature pairs of the first structure are distributed along a first direction, wherein the one or more additional feature pairs of the second structure are distributed along the first direction, wherein the one or more feature pairs of the first structure and the one or more additional feature pairs of the second structure are aligned along a second direction perpendicular to the first second direction.

3. The target of claim 1 , further comprising:
multiple consecutive first structures which are aligned with multiple consecutive second structures.

4. The target of claim 1 , further comprising:
multiple alternating first and second structures.

5. The target of claim 1 , wherein at least one of the unpaired first pair element or the unpaired second pair element are produced using a cutting mask applied to a pre-pattern element of the two or more pre-patterned elements.

6. The target of claim 1 , further comprising:
a previous patterned layer or a post patterned layer.

7. The target of claim 1 , wherein the multiple-patterning process includes three or more patterning processes.

8. The target of claim 1 , wherein the one or more errors in the multiple-patterning process comprise:
a pitch walk.

9. The target of claim 1 , wherein the multiple-patterning process comprises:
at least one of a self-aligned double patterning process, a self-aligned multiple patterning process, a double hardmask patterning process, or a multiple hardmask patterning process.

10. A metrology target, comprising:
a first structure formed from a multiple-patterning process including a first patterning process and a second patterning process, the first structure including one or more feature pairs, wherein a given feature pair of the one or more feature pairs includes a first pair element and a second pair element on a common layer separated by a first pitch, wherein the first structure further includes a first pair element of a separator feature pair on the common layer formed in a common process with the one or more feature pairs, wherein elements of adjacent feature pairs of the one or more feature pairs are separated by a second pitch equal to the first pitch, wherein the first feature element of the separator feature pair is separated from an adjacent element of the one or more feature pairs by the second pitch; and
a second structure formed from the multiple-patterning process, the second structure including one or more additional feature pairs, wherein the second structure further includes a second pair element of the separator feature pair, wherein the first and second pair elements of the separator feature pair are separated by a third pitch larger than the second pitch, wherein elements of adjacent feature pairs of the one or more additional feature pairs are separated by the second pitch, wherein the second pair element of the separator feature pair is separated from an adjacent element of the one or more feature pairs by the second pitch, wherein the one or more feature pairs, the separator feature pair, and the one or more additional feature pairs are formed by the first patterning process generating three or more pre-pattern elements and the second patterning process defining the first pitch and the third pitch based on the three or more pre-pattern elements, wherein an overlay metrology measurement of the metrology target is indicative of one or more errors in the multiple-patterning process manifested as a deviation of the first pitch with respect to the second pitch.

11. The target of claim 10 , further comprising:
a previous patterned layer or a post patterned layer.

12. The target of claim 10 , wherein the multiple-patterning process includes three or more patterning processes.

13. The target of claim 10 , wherein the one or more errors in the multiple-patterning process comprise:
a pitch walk.

14. The target of claim 10 , wherein the multiple-patterning process comprises:
at least one of a self-aligned double patterning process, a self-aligned multiple patterning process, a double hardmask patterning process, or a multiple hardmask patterning process.

15. A method comprising:
fabricating, with a first patterning process of a multiple-patterning process, two or more pre-pattern elements on a common layer associated with a first metrology structure;
fabricating, with the first patterning process, two or more pre-pattern elements on the common layer associated with a second metrology structure;
fabricating, with a second patterning process of the multiple-patterning process, one or more feature pairs defined by at least one of the pre-pattern elements associated with the first metrology structure, wherein a given feature pair of the first metrology structure includes a first pair element and a second pair element separated by a first pitch, wherein elements of adjacent feature pairs of the first metrology structure are separated by a second pitch different than the first pitch;
fabricating, with the second patterning process, an isolated first pair element defined by one of the pre-pattern elements associated with the first metrology structure;
fabricating, with the second patterning process, one or more feature pairs defined by at least one of the pre-pattern elements associated with the second metrology structure, wherein a given feature pair of the second metrology structure includes a first pair element and a second pair element separated by the first pitch, wherein elements of adjacent feature pairs of the first metrology structure are separated by the second pitch;
fabricating, with the second patterning process, an isolated second pair element defined by one of the two or more pre-pattern elements as

Assignees

• Kla Tencor Corp

Inventors

• Amir Nuriel

Classifications

• B05D1/32

  using means for protecting parts of a surface not to be coated, e.g. using stencils, resists · CPC title

• G03F7/70466 Primary

  Multiple exposures, e.g. combination of fine and coarse exposures, double patterning or multiple exposures for printing a single feature (stitching G03F7/70475) · CPC title

• G03F7/70633

  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 title

• G01N21/4785 Primary

  Standardising light scatter apparatus; Standards therefor · CPC title

• G01N21/01 Primary

  Arrangements or apparatus for facilitating the optical investigation · CPC title