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US 9,040,212 B2Granted
Endpoint detection for photolithography mask repair
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsChien-Lin Chen, Chih-Wei Wen, Chung-Hung Lin
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Abstract
A method includes scanning a lithography mask with a repair process, and measuring back-scattered electron signals of back-scattered electrons generated from the scanning. An endpoint is determined from the back-scattered electron signals. A stop point is calculated from the endpoint. The step of scanning is stopped when the calculated stop point is reached.
Claims20
A method comprising:
- scanning a lithography mask using an electron beam to repair the lithography mask, wherein the scanning is performed in an environment comprising a process gas, and wherein the process gas reacts with the lithography mask when stimulated by the electron beam;
- measuring back-scattered electron signals of back-scattered electrons generated from the scanning;
- determining an endpoint from the back-scattered electron signals;
- calculating a stop point from the endpoint;
- and
- stopping the step of scanning when the stop point is reached.
3 more elements
A method comprising:
- scanning a lithography mask using an electron beam to repair the lithography mask, wherein the scanning is performed in an environment comprising a process gas, and wherein the process gas reacts with the lithography mask when stimulated by the electron beam;
- measuring global back-scattered electron signals of back-scattered electrons from the lithography mask;
- smoothing the global back-scattered electron signals to generate smoothed global back-scattered electron signals;
- calculating slopes of the smoothed global back-scattered electron signals in real time;
- comparing the slopes with a pre-selected threshold slope to determine an endpoint, wherein at the endpoint, a first number of loops of scanning have been executed;
- calculating a second number of loops of scanning, wherein the step of calculating the second number comprises multiplying the first number by a constant ratio greater than one to generate a product;
- and
- stopping the step of scanning when the second number of loops of scanning is reached.
5 more elements
A method comprising:
- scanning a lithography mask using an electron beam to repair the lithography mask, wherein the scanning is performed in an environment comprising a process gas, and wherein the process gas reacts with the lithography mask when stimulated by the electron beam;
- determining an endpoint from back-scattered electron signals of back-scattered electrons generated during the scanning;
- performing a first plurality of loops of scanning after the endpoint is reached;
- and
- upon the plurality of loops of scanning is performed, stopping the scanning.
2 more elements
Dependencies are inferred from the claim text.