Embedded Electrode Substrate Support for Uniform Plasma Etching
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Solution Overview
Problem
In semiconductor manufacturing, plasma assisted etching processes face challenges in achieving narrow ranges of high energy ions with low angular distributions, leading to undesirable etch rates and feature deformations in high aspect ratio features due to the oscillating potential difference between the substrate and plasma caused by RF biasing.
Innovation Solution
The use of electrostatic chucking (ESC) substrate supports that provide pulsed DC voltages through capacitive coupling to regions of the substrate, allowing for independent biasing of substrate regions with cyclic DC voltages, which stabilizes the ion acceleration potential and controls ion energy and angular distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If RF power is coupled to the substrate to accelerate ions, then ion acceleration towards the substrate is achieved, but the potential difference oscillates causing large ranges of ion energies and large angular distributions
Solution Approach 1:
The substrate support is divided into multiple independently controllable electrode regions (first electrodes) that can be biased separately. This segmentation allows different regions of the substrate to receive ions with controlled energies and angular distributions, resolving the contradiction by enabling precise local control rather than uniform oscillating bias across the entire substrate.
Solution Approach 2:
The system employs pulsed DC power instead of continuous RF power to create periodic ion acceleration events. By applying DC pulses at controlled frequencies, the system achieves ion acceleration without the continuous oscillation that causes large energy ranges and angular distributions, thereby maintaining manufacturing precision while still achieving effective ion bombardment.
2Productivity
If RF biasing is used to form plasma, then plasma formation is achieved, but feature profile deformations occur due to large angular distributions of ions
Solution Approach 1:
Different regions of the substrate support are equipped with independently controllable electrodes that can apply different bias conditions to different areas. This allows optimization of ion angular distribution for specific feature types (e.g., vertical sidewalls requiring narrow angular distributions) while maintaining high etch rates in other regions, thus preserving feature profile quality without sacrificing productivity.
Solution Approach 2:
The system changes the biasing parameters from continuous RF oscillation to pulsed DC with adjustable pulse width, frequency, and amplitude. By controlling these parameters, the system can optimize ion energy and angular distribution to achieve both high etch rates and straight vertical sidewalls, preventing feature profile deformations while maintaining productivity.
3Manufacturing precision
If multiple electrodes are embedded in the substrate support, then independent region biasing is achieved, but device complexity increases
Solution Approach 1:
The multiple embedded electrodes are designed to perform multiple functions: they serve as both electrostatic clamping elements and independent biasing electrodes for plasma processing. This multi-functionality reduces the need for separate electrode systems, thereby limiting the increase in device complexity while still achieving independent region bias control for enhanced manufacturing precision.
4Manufacturing precision
If pulsed DC power is applied through capacitive coupling, then ion acceleration is stabilized, but energy consumption increases
Solution Approach 1:
The pulsed DC power is applied in a continuous cycle with optimized pulse width and frequency to maintain stable ion acceleration without unnecessary idle time. By keeping the useful action (ion acceleration) continuous and eliminating gaps in the pulsing scheme, the system achieves stable manufacturing precision while minimizing energy consumption compared to less efficient pulsing patterns.
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 enables more uniform and controlled ion acceleration, improving etch rates and feature profiles by maintaining high energy ions and reducing angular distributions, thus enhancing the formation of high aspect ratio features and square etch profiles.
Implementation Method 1
each electrode of the plurality of first electrodes is configured to provide a pulsed DC power to a region of a substrate through capacitive coupling therewith
Implementation Method 2
a second electrode disposed within the substrate support, and electrically isolated from the plurality of first electrodes, for electrically clamping the substrate to the substrate support
Implementation Method 3
a plasma is formed in the processing chamber, and ions from the plasma are accelerated towards the substrate
Implementation Method 4
ions from the plasma are accelerated towards the substrate, and openings formed in a mask thereon
Data Source
AI summary
A method and apparatus for biasing regions of a substrate in a plasma assisted processing chamber are provided. Biasing of the substrate, or regions thereof, increases the potential difference between the substrate and a plasma formed in the processing chamber thereby accelerating ions from the plasma towards the active surfaces of the substrate regions. A plurality of bias electrodes herein are spatially arranged across the substrate support in a pattern that is advantageous for managing uniformity of processing results across the substrate.