Plasma Etching Pulse Control for Shape Accuracy and Mask Protection
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Solution Overview
Problem
As semiconductor devices become finer and denser, plasma etching processes face challenges in maintaining processing performance while suppressing shape abnormalities, which existing technologies struggle to address effectively.
Innovation Solution
A plasma processing apparatus that generates high-density plasma using a source RF signal with alternating high and low states, coupled with a bias DC signal featuring alternating ON and OFF states, to control plasma processing and improve etching performance by alternately supplying pulses of different voltage levels to the substrate support.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional plasma etching is used to maintain processing performance, then etching speed is maintained, but shape abnormalities occur
Solution Approach 1:
The patent applies periodic action by alternating between high-density plasma generation periods (for efficient etching) and low-density plasma generation periods (for shape correction). The RF power to the coil is periodically reduced during etching cycles, creating oscillating plasma density that prevents shape abnormalities while maintaining overall etching speed. This periodic modulation of plasma density resolves the contradiction between maintaining high productivity and achieving precise shape control.
2Productivity
If high-density plasma is generated continuously, then etching speed increases, but mask consumption and lateral etching increase
Solution Approach 1:
The patent implements periodic action by cycling the RF power supplied to the coil between high and low levels during the etching process. During high RF power phases, high-density plasma enables fast etching; during low RF power phases, plasma density reduces, minimizing mask consumption and lateral etching. This temporal separation of high-density and low-density plasma generation within each etching cycle allows the system to achieve high productivity while suppressing harmful side effects.
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 enhances the processing performance of plasma etching by reducing shape abnormalities, improving the etching process through precise control of plasma characteristics and preventing mask consumption and lateral etching issues.
Implementation Method 1
a source RF generator (31a) coupled to the plasma processing chamber (10) and configured to generate a source RF signal including high states and low states in alternate manner
Implementation Method 2
a bias DC generator (32) coupled to the lower electrode (11c) and configured to generate a bias DC signal including ON states and OFF states in alternate manner
Implementation Method 3
apparatus using inductively coupled plasma (ICP, also referred to as transformer coupled plasma (TCP))
Data Source
AI summary
A plasma processing apparatus includes: a plasma processing chamber; a substrate support disposed in the plasma processing chamber and including a lower electrode; a source RF generator coupled to the plasma processing chamber and configured to generate a source RF signal including high states and low states in alternate manner; and a bias DC generator coupled to the lower electrode and configured to generate a bias DC signal including ON states and OFF states in alternate manner. Each ON state includes a plurality of cycles, each cycle including a first sequence of first pulses and a second sequence of second pulses, each first pulse having a first voltage level, and each second pulse having a second voltage level different from the first voltage level.