Resist Pattern Shrinkage Correction for Semiconductor Focus Measurement
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Solution Overview
Problem
The miniaturization of semiconductor integrated circuit element patterns, particularly with dimensions of 65 nm or less, poses challenges in accurate focus measurement due to significant shrinkage of chemically-amplified resist materials when exposed to electron beams, leading to errors in focus measurement and pattern formation.
Innovation Solution
A method involving repeated measurements of resist patterns to calculate shrinkage and create a model of focal dependency, allowing for accurate focus adjustment and correction by referencing shrinkage data, thereby improving focus measurement accuracy even in fine patterns with substantial shrinkage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemically-amplified resist materials are used for miniaturized patterns (65 nm or less), then pattern resolution is improved, but significant shrinkage occurs when exposed to electron beams, leading to measurement errors
Solution Approach 1:
The patent applies preliminary action by pre-measuring the shrinkage characteristics of the resist material under electron beam exposure before actual focus measurement. The system stores shrinkage data corresponding to different focus values in advance, and uses this pre-acquired data to correct focus measurements, thereby eliminating the measurement error caused by resist shrinkage.
Solution Approach 2:
The patent implements feedback by continuously monitoring the shrinkage of resist patterns during electron beam exposure and using this information to adjust and correct focus measurements. The system compares measured pattern dimensions against reference data to detect shrinkage and compensates for it in real-time, ensuring accurate focus determination despite material shrinkage.
2Measurement precision
If repeated electron beam measurements are performed on resist patterns, then shrinkage data can be calculated and focal dependency modeled, but measurement time increases
Solution Approach 1:
The patent reduces measurement time by performing shrinkage measurements and creating focal dependency models in advance, before actual production focus measurements are needed. The pre-acquired shrinkage data and modeled relationships allow for rapid correction of focus measurements without requiring repeated time-consuming measurements during production.
Solution Approach 2:
The patent uses copying by creating reference models of shrinkage behavior under various focus conditions through preliminary measurements. These reference models are then used to correct actual focus measurements without needing to perform identical repeated measurements each time, significantly reducing measurement time while maintaining accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables precise focus value and focal shift length determination, inhibiting focal shift and enhancing the formation of high-accuracy resist patterns, leading to higher production yield in semiconductor devices.
Implementation Method 1
The shrinkage by the electron beam occurs due to an evaporation of residual solvent in the resist and cleavages of polymer bonds by the electron beam irradiation.
Implementation Method 2
when the resist is exposed to an electron beam for measuring the resist dimensions
Data Source
AI summary
In a focus measurement method and a method of manufacturing a semiconductor device relating to the present invention, a focus value is obtained by using a fluctuation where shrinkage of a resist pattern by an electron beam irradiation depends upon the focus value. In the case of obtaining the focus value, the shrinkage of the resist pattern for a focus measurement formed by exposure to be subject for a focus value measurement is measured. The focus value corresponding to the shrinkage is obtained from the pre-obtained focal dependency of the shrinkage. A focal shift length can be defined from a difference between the focus value and a predetermined best focus value.