Globalfoundries Inc.

Globalfoundries U.S. Inc.

Kla Corporation

Pavan Kumar Chinthamanipeta Sripadarao

Xintuo Dai

Dongyue Yang

Minghao Tang

Md Motasim Bellah

Dongsuk Park

Cheuk Wun Wong

Cung D Tran

Ravi Prakash Srivastava

Rui Chen

Sanggil Bae

Bradley Morgenfeld

Huaxiang Li

Christian J Ayala

Kripa Nidhan Chauhan

Two pairs of alignment targets (one aligned, one misaligned by a bias distance) are formed on different masks to produce a first pair of conjugated interference patterns. Other pairs of alignment targets are also formed on the masks to produce a second pair of conjugated interference patterns that are inverted the first. Misalignment of the dark and light regions of first interference patterns and the second interference patterns in both pairs of conjugated interference patterns is determined when patterns formed using the masks are overlaid. A magnification factor (of the interference pattern misalignment to the target misalignment) is calculated as a ratio of the difference of misalignment of the relatively dark and relatively light regions in the pairs of interference patterns, over twice the bias distance. The interference pattern misalignment is divided by the magnification factor to produce a self-referenced and self-calibrated target misalignment amount, which is then output.

Self-referencing and self-calibrating interference pattern overlay measurement

Two pairs of alignment targets (one aligned, one misaligned by a bias distance) are formed on different masks to produce a first pair of conjugated interference patterns. Other pairs of alignment targets are also formed on the masks to produce a second pair of conjugated interference patterns that are inverted the first. Misalignment of the dark and light regions of the first interference patterns and the second interference patterns in both pairs of conjugated interference patterns is determined when patterns formed using the masks are overlaid. A magnification factor (of the interference pattern misalignment to the target misalignment) is calculated as a ratio of the difference of misalignment of the relatively dark and relatively light regions in the pairs of interference patterns, over twice the bias distance. The interference pattern misalignment is divided by the magnification factor to produce a self-referenced and self-calibrated target misalignment amount, which is then output.

In an exemplary method, a first layer is formed on a substrate. First overlay marks are formed in a first zone of the first layer. A non-transparent layer is formed on top of the first layer. At least a portion of the non-transparent layer is removed from an area above the first zone of the first layer. This provides optical access to the first overlay marks. A second layer is formed on top of the non-transparent layer. Second overlay marks are formed in a second zone of the second layer. Position information is obtained from each of the first overlay marks and the second overlay marks.

Structure and method to improve overlay performance in semiconductor devices

Growing community of inventors

Clifton Park, NY, United States of America

Pavan Kumar Chinthamanipeta Sripadarao