Method and apparatus for determining a critical dimension variation of a photolithographic mask
AssigneeCarl Zeiss SMS GmbH
InventorRainer Pforr
Life of this patent
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Abstract
The invention relates to a method for determining a critical dimension variation of a photolithographic mask which comprises (a) using layout data of the photolithographic mask to determine at least two sub-areas of the photolithographic mask, each sub-area comprising a group of features, (b) measuring a distribution of a transmission of each sub-area, (c) determining a deviation of the transmission from a mean transmission value for each sub-area, (d) determining a constant specific for each sub-area, and (e) determining the critical dimension variation of the photolithographic mask by combining for each sub-area the deviation of the transmission and the sub-area specific constant.
Claims23
A method for determining a critical dimension variation of a photolithographic mask, the method comprising:
- a. using layout data of the photolithographic mask to determine at least two sub-areas of the photolithographic mask, each sub-area comprising a group of features;
- b. measuring a distribution of a transmission of each sub-area;
- c. determining a deviation of the transmission from a mean transmission value for each sub-area;
- d. determining a constant specific for each sub-area;
- and
- e. determining the critical dimension variation of the photolithographic mask by combining for each sub-area the deviation of the transmission and the sub-area specific constant.
An apparatus for determining a critical dimension variation of a photolithographic mask comprising:
- a. a computer system operable to determine at least two sub-areas of the photolithographic mask from layout data, each sub-area comprising a group of features, operable to determine a deviation of a transmission from a mean transmission value for each sub-area, to determine a constant specific for each sub-area from the layout data, and to determine the critical dimension variation of the photolithographic mask by combining for each sub-area the deviation of the transmission and the sub-area specific constant;
- and
- b. a metrology tool comprising a source of electromagnetic radiation, a detector system for detecting the electromagnetic radiation of the source and optical means to direct the electromagnetic radiation from the source through the photolithographic mask to the detector system and operable to measure a distribution of the transmission of each sub-area.
Dependencies are inferred from the claim text.