Test structures and methods for monitoring or controlling a semiconductor fabrication process

A test structure formed on a reticle as a monitor for a lithography process, comprising:

• a bright field target comprising first grating structures;
• a dark field target comprising second grating structures, wherein the first and second grating structures have one or more characteristics that are substantially the same as one or more characteristics of device structures formed on the reticle;
• and
• a phase shift target having characteristics that are substantially the same as one or more characteristics of the bright field or dark field target except that grating structures of the phase shift target are shifted in optical phase from the first or second grating structures, wherein one or more of the characteristics of the bright field, dark field, and phase shift targets can be measured and used to determine one or more parameters of the lithography process, wherein the grating structures of the phase shift target comprise sets of segmented structures such that each of the grating structures of the phase shift target comprises at least two segmented structures, and wherein first and second segmented structures of each grating structure of the phase shift target comprise first and second shorter sides, respectively, that are parallel to each other and face each other across a space separating the first and second shorter sides.

A method for monitoring a lithography process, comprising:

• measuring one or more characteristics of a test structure formed on a wafer using the lithography process, wherein the test structure comprises:
• a bright field target comprising first grating structures;
• a dark field target comprising second grating structures, wherein the first and second grating structures have one or more characteristics that are substantially the same as one or more characteristics of device structures formed on the wafer;
• and
• a phase shift target having characteristics that are substantially the same as one or more of the characteristics of the bright field or dark field target except that grating structures of the phase shift target are shifted in optical phase from the first or second grating structures, wherein the grating structures of the phase shift target comprise sets of segmented structures such that each of the grating structures of the phase shift target comprises at least two segmented structures, and wherein first and second segmented structures of each grating structure of the phase shift target comprise first and second shorter sides, respectively, that are parallel to each other and face each other across a space separating the first and second shorter sides;
• and
• determining one or more parameters of the lithography process from the one or more characteristics of the test structure.

A method for controlling an etch process, comprising:

• measuring one or more characteristics of a test structure formed on a wafer using a lithography process, wherein the test structure comprises:
• a bright field target comprising first grating structures;
• a dark field target comprising second grating structures, wherein the first and second grating structures have one or more characteristics that are substantially the same as one or more characteristics of device structures formed on the wafer;
• and
• a phase shift target having characteristics that are substantially the same as one or more of the characteristics of the bright field or dark field target except that grating structures of the phase shift target are shifted in optical phase from the first or second grating structures, wherein the grating structures of the phase shift target comprise sets of segmented structures such that each of the grating structures of the phase shift target comprises at least two segmented structures. and wherein first and second segmented structures of each grating structure of the phase shift target comprise first and second shorter sides, respectively, that are parallel to each other and face each other across a space separating the first and second shorter sides;
• and
• determining one or more parameters of the etch process from the one or more characteristics of the test structure.