EUV Exposure Apparatus Alignment Compensation for Focus Offset Distortion
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Solution Overview
Problem
In EUV exposure apparatuses used for semiconductor manufacturing, positional deviation errors occur due to non-telecentric exposure light and focus offset variations, leading to pattern defects and reduced alignment accuracy, which affects the yield and productivity of semiconductor devices.
Innovation Solution
The exposure apparatus measures positional deviation distributions for various focus offset quantities, calculates distortion errors, and determines correlation between focus offset and alignment compensation values to adjust for these errors, improving alignment accuracy by compensating for distortion using a calculation unit and control system that includes a mask stage, substrate stage, and measurement instruments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If non-telecentric exposure light is used in EUV exposure apparatus, then illumination efficiency is improved, but positional deviation error increases leading to reduced alignment accuracy
Solution Approach 1:
The patent changes the parameter of illumination telecentricity from non-telecentric to telecentric configuration. By adjusting the illumination optical system to provide telecentric light, the positional deviation error is reduced while maintaining exposure efficiency, thus resolving the contradiction between illumination efficiency and alignment accuracy.
2Adaptability or versatility
If focus offset varies between quality control and actual device production, then production flexibility is improved, but distortion error increases leading to pattern defects
Solution Approach 1:
The patent performs preliminary measurement of positional deviation distribution at multiple focus offsets during quality control. By pre-characterizing the distortion behavior at different focus offsets, the system can later compensate for distortion errors during actual production even when focus offset varies, thus maintaining pattern accuracy while allowing production flexibility.
Solution Approach 2:
The patent implements a feedback mechanism where measured positional deviation data from quality control is used to calculate and apply distortion compensation values during production. This closed-loop approach allows the system to adapt to focus offset variations while maintaining manufacturing precision through continuous compensation.
3Manufacturing precision
If alignment accuracy is improved through multiple measurements, then pattern defect rate is reduced, but measurement time increases affecting productivity
Solution Approach 1:
The patent performs comprehensive measurements of positional deviation distribution at multiple focus offsets during the quality control phase before production. By completing these measurements in advance, the system establishes a compensation model that can be rapidly applied during production without requiring repeated measurements, thus achieving high alignment accuracy while maintaining productivity.
Data Source
AI summary
According to one embodiment, there is provided an exposure apparatus including an acquisition unit, and a calculation unit. The acquisition unit obtains a plurality of measured values. The plurality of measured values is measured for a plurality of focus offset quantities different from each other. Each of the plurality of measured values represents positional deviation distribution within a shot area. The calculation unit calculates a plurality of distortion errors from the plurality of measured values and obtains a correlation between the focus offset quantity and alignment compensation value to compensate for the distortion error, in response to the plurality of focus offset quantities and the plurality of distortion errors.