Plasma Processing Cycle With Tungsten Layer for Selective Oxide Etching
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Solution Overview
Problem
Current substrate processing methods face challenges in achieving selective etching between regions of different materials, such as silicon and silicon nitride, with existing plasma etching techniques often resulting in poor etching selectivity and clogging issues.
Innovation Solution
A substrate processing method involving a plasma processing apparatus that cycles through specific power levels of radio-frequency power and electrical bias to form a tungsten deposit on one region, modify it, and then use high-energy ions to etch the other region while protecting the first region with the modified deposit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etching is used to etch silicon oxide, then etching can be performed, but etching selectivity between silicon oxide and silicon nitride deteriorates
Solution Approach 1:
A tungsten deposit is formed on the silicon nitride region before the etching process begins. This preliminary deposit serves as a protective layer that prevents clogging during subsequent etching operations and maintains etching selectivity between silicon oxide and silicon nitride regions.
Solution Approach 2:
The tungsten deposit acts as an intermediary layer between the plasma etching process and the silicon nitride region. It mediates the interaction by providing a protective barrier that prevents direct contact between the etching plasma and the silicon nitride, thereby preventing clogging while allowing selective etching of silicon oxide.
2Productivity
If high power radio-frequency power is applied to etch silicon oxide, then etching speed increases, but damage to silicon nitride region increases
Solution Approach 1:
The tungsten deposit is formed in advance on the silicon nitride region to create a protective barrier. This allows high power radio-frequency power to be applied for fast silicon oxide etching without causing damage to the silicon nitride region, as the deposit absorbs or deflects the harmful plasma effects.
Solution Approach 2:
The high energy plasma that would normally cause damage to silicon nitride is converted into a beneficial effect by the tungsten deposit. The deposit absorbs the excess energy and plasma flux, protecting the silicon nitride while still allowing efficient silicon oxide etching to proceed at high speed.
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 improves etching selectivity by protecting the second region and preventing clogging, allowing for precise etching of the first region while maintaining the integrity of the second region.
Implementation Method 1
a source radio-frequency power for generating plasma from the processing gas in the chamber
Implementation Method 2
a level of an electrical bias supplied to the substrate support unit
Data Source
AI summary
A substrate processing method (a) provides a substrate on a substrate support unit provided in a chamber, and (b) supplies a processing gas into the chamber. The substrate includes a first region formed of a material including silicon and a second region formed of a material different from the material of the first region. The processing gas includes tungsten and a component for etching the first region. The substrate processing method (c) repeats a cycle while the processing gas is supplied into the chamber at (c). The cycle includes first to third processes. The power level of a source radio-frequency power in the first process is higher than the power level of the source radio-frequency power in each of the second and third processes.