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
An apparatus for determining a stop point for repairing a lithography mask, the apparatus comprising:
- a gas reservoir having an outlet pointing at the lithography mask;
- an e-beam generator configured to generate an e-beam to scan the lithography mask;
- a Back-Scattered Electron (ESB) detector configured to detect back-scattered electrons scattered from scanned portions of the lithography mask and to generate signals;
- and
- a control unit coupled to the e-beam generator and the ESB detector, wherein the control unit is configured to:
- process the signals generated by the ESB detector, and to determine a stop point from the signals;
- and
- stop the repairing the lithography mask when the stop point is reached, wherein at the stop point, an opaque pattern in the scanned portions of the lithography mask is removed to expose an underlying substrate.
An apparatus for determining a stop point for repairing a lithography mask, the apparatus comprising:
- an e-beam generator configured to generate an e-beam to scan the lithography mask;
- a Back-Scattered Electron (ESB) detector configured to detect back-scattered electrons scattered from scanned portions of the lithography mask and to generate signals;
- and
- a control unit coupled to the e-beam generator and the ESB detector, wherein the control unit is configured to:
- determine an endpoint from the signals, wherein at the endpoint, the signals start to have a dropping rate greater than a pre-determined dropping rate;
- calculate a stop point from the endpoint, wherein at the stop point, the signals are substantially flat;
- and
- stop the e-beam generator from generating the e-beam when the stop point is reached.
An apparatus comprising:
- an e-beam generator configured to generate an e-beam;
- a Back-Scattered Electron (ESB) detector configured to detect back-scattered electrons resulted from the e-beam;
- and
- a control unit configured to:
- receive signals from the ESB detector;
- calculate an endpoint from the signals;
- calculate a stop point from the endpoint;
- and
- stop the e-beam generator from generating the e-beam when the stop point is reached.
Dependencies are inferred from the claim text.