Pulsed DC Voltage Control for Plasma Etching Uniformity
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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.
Innovation Solution
A substrate support assembly with embedded electrodes connected to switches that can independently control pulsed DC voltage frequency and duty cycle, allowing for precise ion energy and angular distribution management during plasma assisted processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If low frequency 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 patent applies periodic pulsed DC voltage to the substrate through a switching system that alternates between applying voltage and grounding the substrate. This periodic action creates distinct ion acceleration phases followed by relaxation phases, resulting in narrow energy distributions and low angular distributions of ions at the substrate surface, thereby resolving the contradiction between achieving ion acceleration and maintaining manufacturing precision.
2Productivity
If RF biasing is used to couple power to the substrate, then ion acceleration is achieved, but feature profile deformations such as necking and bowing occur
Solution Approach 1:
The pulsed DC voltage system creates periodic ion bombardment cycles that allow for controlled etching with minimal profile deformation. The periodic nature of the voltage application ensures that ions arrive at the substrate with consistent energies and angles, maintaining straight vertical sidewalls and preventing necking and bowing while still achieving high etch rates.
3Duration of action of moving object
If continuous RF power is applied to the substrate, then continuous ion acceleration occurs, but control over ion energy and angular distribution is reduced
Solution Approach 1:
The switching system implements periodic voltage application with controlled pulse widths and frequencies, allowing precise control over the duration and timing of ion acceleration events. This periodic control mechanism enables independent adjustment of ion energy and angular distribution parameters, achieving narrow energy ranges and low angular distributions while maintaining continuous processing capability.
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 solution enables improved processing uniformity and control over etch rates, reducing feature deformations and enhancing the formation of high aspect ratio features with straight profiles.
Implementation Method 1
an electrostatic chucking electrode planarly embedded in the substrate support
Implementation Method 2
a plasma generating apparatus. The plasma generating apparatus may comprise a plasma electrode disposed in the processing volume facing the substrate support, and an RF power conduit connected to the plasma electrode
Implementation Method 3
The plasma generating apparatus may comprise and inductively coupled plasma system
Implementation Method 4
ions from the plasma are accelerated towards the substrate, and openings formed in a mask thereon
Data Source
AI summary
The present disclosure generally relates to plasma assisted or plasma enhanced processing chambers. More specifically, embodiments herein relate to electrostatic chucking (ESC) substrate supports configured to provide independent pulses of DC voltage through a switching system to electrodes disposed through the ESC substrate support, or to electrodes disposed on a surface of the ESC, or to electrodes embedded in the ESC substrate support. The switching system can independently alter the frequency and duty cycle of the pulsed DC voltage that is coupled to each electrode. During processing of the substrate, the process rate, such as etch rate or deposition rate, can be controlled independently in regions of the substrate because the process rate is a function of the frequency and duty cycle of the pulsed DC voltage. The processing uniformity of the process performed on the substrate is improved.