Patent ID: 7608468
Filing Date: 2009-10-27
Classification: G03F,G06F,Y02P

Abstract:
1. A method of monitoring or adjusting a process for fabricating a product specimen, the method comprising: providing a plurality of targets on a product specimen having a plurality of active devices, wherein at least some of the targets are distributed across a field of a lithography tool which was used to fabricate the product specimen and wherein the number and positions of the targets are selected such that a nonlinear dependence curve for a lithography tool and a characteristic of the targets can be determined as a function of field position across the field by measuring the characteristic of each of the targets that are distributed across the field, wherein the targets are distributed across the field by distributing the targets along a street that separates two rows or columns of dies of the field and/or integrating the targets within a plurality of dies that are distributed across the field; measuring the characteristic of each of the targets which are distributed across the field; determining a nonlinear dependence curve for the lithography tool as a function of field position across the field, wherein the nonlinear dependence curve is determined by fitting a nonlinear function to the targets' measured characteristics; and using the determined nonlinear dependence curve to monitor or adjust a process for fabricating the product specimen with the lithography tool.