Pulsed Pedestal Bias for Stable High-Aspect-Ratio Etching
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Solution Overview
Problem
Existing etching technologies struggle to stably implement etching with high aspect ratios in semiconductor manufacturing, particularly in plasma etching processes.
Innovation Solution
An etching apparatus and method that alternately performs film formation and etching steps with differently set duty ratios for pulsed voltages, using a power source to apply pulsed voltages with varying ON periods in each cycle, specifically through the use of a capacitively coupled plasma processing apparatus with controlled RF and DC signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional etching processes are used, then etching speed is maintained, but stable etching with high aspect ratios cannot be achieved
Solution Approach 1:
The patent applies periodic pulsed voltages to the substrate during etching, alternating between etching steps and film formation steps. This periodic action allows ions to be accelerated into the substrate during etching steps while forming protective films during film formation steps, enabling stable high aspect ratio etching that conventional continuous processes cannot achieve
Solution Approach 2:
The patent changes multiple parameters including voltage amplitude, pulse width, duty ratio, and gas composition between etching and film formation steps. These parameter changes enable control over ion acceleration, film deposition rate, and plasma chemistry, collectively achieving the capability to etch high aspect ratio structures with uniformity
2Productivity
If high power is applied to increase etching speed, then productivity improves, but abnormal discharge and defects occur
Solution Approach 1:
By applying pulsed voltages with specific duty ratios rather than continuous high power, the system achieves high etching speed during active etching steps while allowing plasma to stabilize and films to form during idle steps, preventing abnormal discharge and maintaining process reliability
Solution Approach 2:
The patent forms protective films on the substrate surface before subsequent high-power etching steps. These pre-formed films cushion against the high energy ion bombardment, preventing damage and abnormal discharge while allowing high productivity during the etching steps
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
Stable etching with high aspect ratios is achieved, suppressing defects like abnormal discharge while efficiently etching deep recesses in semiconductor wafers.
Implementation Method 1
capacitively coupled plasma processing apparatus
Implementation Method 2
periodically applies, to the placing pedestal, pulsed voltages
Data Source
AI summary
A placing pedestal on which a substrate is to be mounted is provided in the interior of a chamber. When etching a substrate mounted on the placing pedestal by alternately performing a first step of forming a film on the substrate and a second step of etching the substrate in the chamber, the power source periodically applies, to the placing pedestal, pulsed voltages in which the duty ratio in one cycle is set differently between the first step and the second step.