Self-Assembled Monolayer Etching for Silicon Uniformity
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Solution Overview
Problem
Conventional etching methods for semiconductor devices face challenges in achieving uniform etch depth and aspect ratio-dependent transport, particularly in etching silicon-containing layers, leading to non-uniformity and inefficiencies in feature formation.
Innovation Solution
A cyclical process involving a deposition phase and an activation phase in a plasma processing chamber, where a self-limiting monolayer is formed using a precursor with a head group and a fluorine and carbon tail group, and activated through ion bombardment to selectively etch the silicon-containing layer, reducing unwanted etching and improving control over the etching process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching methods are used to etch silicon-containing layers, then etching can be performed, but etch depth uniformity deteriorates and aspect ratio-dependent transport issues occur
Solution Approach 1:
The etching process is divided into multiple alternating phases: a deposition phase where a self-limiting monolayer is formed using a precursor gas, and an activation phase where ion bombardment activates the monolayer for etching. This segmentation allows precise control over etch depth by controlling the number of cycles and parameters of each phase, eliminating aspect ratio-dependent transport issues while achieving uniform etch depth across features of varying aspect ratios.
Solution Approach 2:
The patent employs periodic cycling between deposition and activation phases. Each cycle deposits a controlled monolayer followed by activation for etching, repeating this sequence to achieve the desired etch depth. This periodic action provides precise control over etch depth uniformity and eliminates transport issues by resetting conditions with each cycle, allowing consistent etching performance regardless of feature geometry.
2Productivity
If conventional plasma etching is used, then etching speed can be maintained, but selectivity between horizontal and vertical surfaces deteriorates
Solution Approach 1:
The self-limiting monolayer formed during the deposition phase exhibits local quality differences based on surface orientation. The monolayer forms with different characteristics on horizontal versus vertical surfaces, and the ion bombardment activation selectively removes material from horizontal surfaces while preserving vertical surfaces. This local quality differentiation achieves high selectivity between surface orientations while maintaining overall etching productivity through controlled cycle repetition.
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 enhances etch depth uniformity and reduces aspect ratio-dependent transport issues, allowing for precise and efficient etching of silicon-containing layers with improved selectivity between horizontal and vertical surfaces, thereby improving the overall performance of semiconductor device fabrication.
Implementation Method 1
flowing a precursor into the plasma processing chamber to form a self-limiting monolayer
Implementation Method 2
providing an activation bias in the plasma processing chamber to cause ion bombardment of the self-limiting monolayer, wherein the ion bombardment activates the fluorine from the tail group component to etch the silicon containing layer
Implementation Method 3
creating a plasma in the plasma processing chamber from the activation gas
Data Source
AI summary
A method for etching features into a silicon containing layer comprising performing a plurality of cycles in a plasma processing chamber is provided. Each cycle comprises a deposition phase and an activation phase. The deposition phase comprises flowing a precursor into the plasma processing chamber to form a self-limiting monolayer, wherein the precursor comprises a head group component and a tail group component, wherein the tail group component comprises fluorine and carbon, and stopping the flow of the precursor into the plasma processing chamber. The activation phase comprises flowing an activation gas comprising an ion bombardment gas, into the plasma processing chamber, creating a plasma from the activation gas, providing an activation bias to cause ion bombardment of the self-limiting monolayer, wherein the ion bombardment activates the fluorine from the tail group component to etch the silicon containing layer, and stopping the flow of the activation gas.