Substrate Etching Condition Selection Using Thickness Pattern Matching
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Solution Overview
Problem
The existing semiconductor device's correspondence table for etching insulating films on substrates only considers average film thicknesses, leading to variations in film thickness across wide areas, as etching at specific points affects the film thickness distribution, resulting in uneven etching outcomes.
Innovation Solution
A method for selecting processing conditions by measuring substrate thickness at multiple points, comparing these patterns to pre-stored reference patterns, and acquiring associated processing conditions to minimize thickness variations, involving classification into shape-based reference groups and adjusting nozzle movements based on etch rate and thickness correlations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a correspondence table based on average film thickness is used to determine etching time, then the etching time can be determined simply, but the film thickness uniformity across the substrate deteriorates
Solution Approach 1:
The substrate surface is divided into multiple measurement points (e.g., 25 points) to capture local thickness variations. Instead of using a single average value, the patent segments the measurement area to identify regional thickness patterns, which are then used to select appropriate etching conditions for different areas.
Solution Approach 2:
The patent applies different etching times to different regions of the substrate based on local thickness characteristics. By identifying thick and thin regions through multi-point measurement and applying spatially-varying etching conditions, the method achieves uniform thickness across the entire substrate after etching.
2Device complexity
If etching is performed based on average film thickness only, then the processing condition selection is simplified, but the thickness variation across wide areas increases
Solution Approach 1:
The patent transitions from one-dimensional average thickness measurement to two-dimensional spatial distribution measurement by measuring at multiple points across the substrate surface. This dimensional expansion enables identification of thickness patterns and variation trends that are invisible in average values alone.
Solution Approach 2:
The patent performs preliminary measurement of film thickness at multiple points before etching to establish the initial thickness distribution pattern. This preliminary information is used to pre-determine the etching conditions, allowing the process to compensate for thickness variations before they occur.
3Productivity
If a single etching time is applied to the entire substrate, then the processing process is simplified, but the etching uniformity across different regions deteriorates
Solution Approach 1:
The patent introduces dynamic etching conditions where the etching time varies spatially across the substrate. By making the etching parameters dynamic and position-dependent rather than static and uniform, the system achieves better etching uniformity while maintaining reasonable processing efficiency.
Data Source
AI summary
A processing condition selection method includes a step (S21) and a step (S22). In the step (S21), a thickness pattern TM that represents a distribution of thicknesses measured at respective measurement points on a target is compared to pre-stored reference patterns (RP) to specify a reference pattern (RP) having a high correlation with the thickness pattern (TM) from among the reference patterns (RP) based on a prescriptive rule. In the step (S22), a reference processing condition associated with the specified reference pattern (RP) is acquired as a processing condition for the target from among reference processing conditions associated with the respective reference patterns (RP). The reference patterns (RP) each represent a distribution of physical quantities of a corresponding one of reference targets. The reference processing conditions each are a processing condition when processing is previously performed on a corresponding one of the reference targets with a corresponding one of the reference patterns (RP).