Exposure Map Correction for Semiconductor Mask Deviations
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Solution Overview
Problem
The microminiaturization of semiconductor devices requires precise control of photomask pattern dimensions to ensure uniformity in resist patterns formed on substrates, but inevitable mask dimension errors lead to systematic deviations affecting device characteristics, necessitating a method to correct these errors during exposure processing.
Innovation Solution
An exposure map system is used to determine exposure corrections for each position on the wafer based on the deviation of mask pattern shapes from ideal shapes, incorporating both mask manufacturing and optical simulation data to create a distribution of exposure dosages that corrects for systematic errors in pattern formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photomask pattern dimensions are strictly controlled to ensure uniformity, then resist pattern uniformity is improved, but manufacturing complexity and cost increase due to the need for extremely precise mask fabrication
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the relationship between mask pattern deviations and exposure corrections in a lookup table before actual production. This allows the exposure apparatus to quickly retrieve and apply appropriate corrections without performing complex real-time calculations, thus maintaining resist pattern uniformity while simplifying the operational complexity.
Solution Approach 2:
The patent changes the parameter of exposure energy by position based on retrieved correction values. Instead of maintaining strictly uniform mask dimensions, the system compensates for mask variations by adjusting exposure parameters, thereby achieving uniform resist patterns while accepting practical mask manufacturing tolerances.
2Measurement precision
If mask dimension errors are completely eliminated, then pattern dimension accuracy is improved, but manufacturing time and cost increase due to the need for ultra-precise mask manufacturing processes
Solution Approach 1:
The patent performs preliminary measurement and characterization of mask pattern dimensions, storing the actual deviations in a lookup table. This pre-characterization allows for rapid compensation during exposure without requiring time-consuming real-time measurements or ultra-precise mask manufacturing, thus maintaining pattern dimension accuracy while reducing mask manufacturing time requirements.
Solution Approach 2:
The patent implements feedback by using measured mask pattern deviations to generate correction values that are stored and later applied during exposure. This closed-loop approach compensates for mask dimension errors, achieving high pattern dimension accuracy without requiring perfectly precise mask manufacturing.
3Manufacturing precision
If exposure corrections are applied for each position on the wafer, then pattern uniformity is improved, but processing time and computational complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating exposure corrections for various mask deviation scenarios and storing them in a lookup table. During actual exposure, the system quickly retrieves the appropriate correction values based on the actual mask measurements, avoiding time-consuming real-time calculations while maintaining pattern uniformity.
Solution Approach 2:
The patent segments the exposure correction process into discrete, pre-calculated values corresponding to different position and deviation combinations. This segmentation allows for efficient lookup and application of corrections without requiring continuous complex computations, thus maintaining pattern uniformity while reducing processing time.
4Reliability
If sophisticated exposure correction systems are implemented, then device performance stability is improved, but system complexity and initial investment increase
Solution Approach 1:
The patent applies preliminary action by pre-establishing the relationship between mask deviations and exposure corrections through measurements and calculations, storing this knowledge in a lookup table. This approach provides robust device performance stability through systematic correction while keeping the actual exposure system relatively simple, as it primarily involves measurement, table lookup, and parameter adjustment rather than complex real-time control mechanisms.
Data Source
AI summary
According to one embodiment, a deviation amount distribution of a two-dimensional shape parameter between a mask pattern formed on a mask and a desired mask pattern is acquired as a mask pattern map. Such that a deviation amount of the two-dimensional shape parameter between a pattern on substrate formed when the mask is subjected to exposure shot to form a pattern on a substrate and a desired pattern on substrate fits within a predetermined range, an exposure is determined for each position in the exposure shot in forming the pattern on substrate based on the mask pattern map.