Fine Pattern Cutting with Sacrificial Layer and Mixed-Gas Etching
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Solution Overview
Problem
The existing methods for forming fine patterns in semiconductor manufacturing face challenges such as the loss of photoresist patterns during etching, leading to a decrease in process margin due to the enlargement of openings and lowering of sidewall slopes, which affects the precision and effectiveness of pattern cutting.
Innovation Solution
A method involving the formation of a line structure with a sacrificial layer and a mask, where a photoresist pattern and a silicon oxynitride mask are used to create openings with controlled etching, using SF6 and CHF3 gases to form carbon-sulfur bonds and restrain etching, allowing for precise cutting of patterns with vertical sidewalls and minimal byproduct formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to form fine patterns, then the etching process can be completed, but the photoresist pattern is easily removed during etching, causing the opening width to enlarge and sidewall slope to decrease, which reduces manufacturing precision
Solution Approach 1:
A sacrificial layer is introduced as an intermediary between the photoresist pattern and the etching process. This sacrificial layer protects the photoresist pattern from being removed during etching, while still allowing the etching gas to pass through and etch the underlying structures. The sacrificial layer acts as a mediator that enables the etching process to proceed without compromising the integrity of the photoresist pattern, thereby maintaining manufacturing precision.
Solution Approach 2:
The etching gas composition is changed from conventional single-gas etching to a mixed gas composition containing SF6 and CHF3. This parameter change in the etching process creates carbon-sulfur bonds on the photoresist pattern surface, which protects the photoresist from removal while maintaining vertical sidewalls and controlling opening width, thus improving manufacturing precision.
2Productivity
If the photoresist pattern is removed during etching, then the etching process can proceed, but the opening width enlarges and sidewall slope decreases, reducing process margin
Solution Approach 1:
The sacrificial layer serves as a mediator that allows the etching process to proceed efficiently while preventing the photoresist pattern from being removed. This enables maintaining steep sidewall slopes and controlled opening widths without compromising etching efficiency, thus resolving the contradiction between productivity and manufacturing precision.
3Manufacturing precision
If standard etching gases are used, then the etching process can be completed, but carbon-sulfur bonds are not formed on the photoresist surface, leading to photoresist removal and reduced pattern fidelity
Solution Approach 1:
The etching gas composition is changed from standard single-gas formulations to a mixed gas containing SF6 and CHF3. This parameter change enables the formation of carbon-sulfur bonds on the photoresist surface during etching, which protects the photoresist pattern and maintains high pattern fidelity. Although the gas composition becomes more complex, the improvement in manufacturing precision justifies the increased device complexity.
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 enhances the precision and reliability of pattern cutting by maintaining a small width of openings and reducing failures, thereby increasing the process margin and efficiency in dividing patterns into multiple pieces.
Implementation Method 1
The etching process may be performed using a first etching gas including SF6 gas and CHF3 gas so that carbon-sulfur (C—S) bonds may be formed on a surface of the photoresist pattern to restrain etching of the photoresist pattern
Data Source
AI summary
In a method of cutting a fine pattern, a line structure is formed on a substrate. The line structure extends in a first direction, and includes a pattern and a first mask. The pattern and the first mask include different materials. A sacrificial layer is formed on the substrate to cover the line structure. The sacrificial layer is partially etched to form a first opening partially overlapping the line structure in a vertical direction. A portion of the first mask, an upper portion of the pattern and/or a portion of the sacrificial layer under the first opening are partially etched using an etching gas having no etching selectivity among the pattern, the first mask and the sacrificial layer. A lower portion of the pattern under the upper portion thereof is removed to divide the pattern into a plurality of pieces spaced apart from each other in the first direction.