Plasma Etching of Recess Bottoms Without Shoulder Blockage
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Solution Overview
Problem
Current etching methods face challenges in effectively etching the bottom portion of a recess on a substrate while protecting the shoulder portion and mask, particularly in achieving precise control over the deposition and removal of materials to prevent scraping or blockage.
Innovation Solution
An etching method involving the use of first and second plasmas generated from distinct process gases, where the first plasma with carbon and oxygen forms a deposit on the shoulder portion, and the second plasma etches the bottom portion, allowing for controlled etching while protecting the shoulder and mask, with specific gas flow rates and compositions optimizing the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a deposit is formed on the mask to protect it during etching, then the mask is protected from damage, but the shoulder portion may be excessively covered causing blockage or scraping issues
Solution Approach 1:
The patent applies local quality by making the deposit thickness location-dependent: thicker on the mask for protection, thinner or absent on the shoulder portion to prevent blockage. This is achieved through controlled plasma deposition parameters that enable selective thickness distribution across different substrate regions.
Solution Approach 2:
The patent changes deposition parameters (plasma power, gas flow rates, deposition time) to control the thickness and distribution of the deposit. By adjusting these parameters, the process optimizes protection on the mask while minimizing excessive coverage on the shoulder portion.
2Loss of substance
If the shoulder portion is etched aggressively to remove deposit, then deposit is removed effectively, but the mask and recess bottom may be damaged
Solution Approach 1:
The etching process applies local quality by making etching rate location-dependent: higher on the shoulder portion to remove deposit, lower on the mask and recess bottom to prevent damage. This is achieved through plasma parameter control that enables selective etching across different regions.
Solution Approach 2:
The patent uses dynamic control of plasma parameters (power, gas flow, pressure) during the etching process to adjust etching rates in real-time. This enables effective deposit removal on the shoulder while protecting the mask and recess bottom from excessive etching.
3Productivity
If plasma parameters are increased to improve etching speed, then productivity increases, but control precision over deposit formation and removal decreases
Solution Approach 1:
The patent employs dynamic adjustment of plasma parameters during the process. By modulating plasma power, gas flow rates, and pressure in real-time, the system maintains high etching speeds while preserving precise control over deposit formation and removal. This dynamic control enables rapid processing without sacrificing precision.
Solution Approach 2:
The patent uses periodic alternation between deposition and etching phases with optimized parameter sets for each phase. During deposition, parameters favor film formation; during etching, parameters favor material removal. This periodic switching enables high overall productivity while maintaining precise control at each stage.
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 enables precise etching of the recess bottom while maintaining the integrity of the shoulder and mask, reducing the risk of scraping and blockage, and improving etching resistance, as demonstrated by experimental results showing controlled thickness changes and etching performance.
Implementation Method 1
forming a deposit on the shoulder portion with first plasma generated from a first process gas containing a gas containing carbon and oxygen
Implementation Method 2
forming a deposit on the shoulder portion with first plasma
Implementation Method 3
etching a bottom portion of the recess with second plasma generated from a second process gas different from the first process gas
Data Source
AI summary
An etching method comprising (a) providing a substrate including a first region having an opening and a second region located below the first region, the second region including a recess communicating with the opening, when viewed from a direction perpendicular to a main surface of the substrate, the second region including a shoulder portion located in the opening, the shoulder portion including an upper end of a side wall of the recess, the second region containing silicon and a material different from a material contained in the first region, (b) forming a deposit on the shoulder portion with first plasma generated from a first process gas containing a gas containing carbon and oxygen, and (c) etching a bottom portion of the recess with second plasma generated from a second process gas different from the first process gas.