Plasma Etching with Sidewall Silicon Deposition to Prevent Mask Bowing
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Solution Overview
Problem
Current plasma etching methods for semiconductor devices face challenges in preventing 'bowing' of organic mask films, which leads to incomplete etching due to widening of mask openings, despite existing technologies using oxygen and carbonyl sulfide gases to reduce this issue.
Innovation Solution
A plasma etching method involving a two-step process: first, etching the target film using a patterned mask, and second, depositing a silicon-containing film on the side walls of the etched film using silicon-containing gases to correct bowing and maintain the desired shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If oxygen gas and carbonyl sulfide gas are used as process gases to reduce bowing, then bowing is reduced, but the problem of incomplete etching due to mask opening widening remains unresolved
Solution Approach 1:
The etching process is divided into multiple sequential steps with different process gases. The first step uses oxygen gas and carbonyl sulfide gas to reduce bowing, while subsequent steps use other process gases to complete the etching of the target film through the widened mask opening, ensuring both shape control and etching completeness
Solution Approach 2:
The patent implements a continuous multi-step process where each step builds upon the previous step. The first step addresses bowing reduction, and subsequent steps continue the etching action through the mask opening, maintaining continuous useful action to achieve both shape control and complete etching
2Manufacturing precision
If the mask pattern size is reduced to form fine circuit patterns, then finer patterns are achieved, but bowing occurs causing the mask to collapse and close the opening
Solution Approach 1:
The patent applies preliminary action by performing bowing reduction in the first etching step before the mask collapse can occur. By using oxygen gas and carbonyl sulfide gas initially, the process prevents the widening that would lead to mask collapse, thereby maintaining opening stability even for reduced mask pattern sizes
Solution Approach 2:
The patent changes process parameters by using different process gases at different steps. The first step uses oxygen gas and carbonyl sulfide gas with specific flow rate ratios to control bowing, while subsequent steps use different gases to complete etching, thereby maintaining mask opening stability throughout the process
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 method effectively prevents bowing, allowing for the formation of precise, vertically shaped openings with high aspect ratios and maintaining the critical dimensions of the etched features, thereby enhancing the etching process for semiconductor devices.
Implementation Method 1
a second step of depositing a silicon-containing film using plasma of a silicon-containing gas on at least a part of a side wall of the etching target film etched by the first step
Implementation Method 2
a first step of plasma-etching the etching target film using the mask
Data Source
AI summary
A plasma etching method for plasma-etching an object including an etching target film and a patterned mask. The plasma etching method includes a first step of plasma-etching the etching target film using the mask, and a second step of depositing a silicon-containing film using plasma of a silicon-containing gas on at least a part of a side wall of the etching target film etched by the first step.