Tapered Edge Substrate Support for Plasma Etch Uniformity
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Solution Overview
Problem
Current semiconductor substrate processing techniques experience non-uniform etch rates at the edge of the substrate due to contaminants and edge effects, which can adversely affect subsequent processes and device performance.
Innovation Solution
A substrate support with a conductive plate having a tapered edge and a dielectric insulator plate, where the conductive plate is coupled to an RF biasing source, is used to improve etch rate uniformity by minimizing edge effects through the configuration of the substrate support and dielectric plate, which helps in maintaining contact and aligning components for uniform plasma formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional substrate support with a flat conductive plate is used, then the structure is simple and easy to manufacture, but non-uniform etch rates occur at the substrate edge
Solution Approach 1:
The conductive plate features a tapered edge portion where the thickness varies radially, creating different local properties at different locations. The edge portion has reduced thickness compared to the center, which locally modifies the plasma distribution and etch rate characteristics to achieve uniform etching across the substrate surface.
Solution Approach 2:
The solution transitions from a two-dimensional flat plate to a three-dimensional structure with varying thickness. By introducing the thickness dimension that tapers radially outward, the design compensates for edge effects and achieves uniform plasma distribution and etch rate across the substrate.
2Manufacturing precision
If the conductive plate thickness is uniform, then the manufacturing is simpler, but edge effects cause non-uniform plasma formation
Solution Approach 1:
The conductive plate is designed with non-uniform thickness, specifically a tapered edge portion that is thinner than the central region. This local variation in thickness creates the desired plasma uniformity by reducing edge effects, while the manufacturing complexity increases due to the precision required in creating the tapered geometry.
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
The solution effectively reduces etch nonuniformity at the substrate edge, even under high bias conditions, leading to improved process control and uniform material removal across the substrate, enhancing the yield and quality of semiconductor devices.
Implementation Method 1
a biasing radio frequency (RF) source to attract the argon molecules toward the substrate
Implementation Method 2
an etch using an ionized form of an inert gas such as argon. The etching process may take place in a chamber in which a plasma of an inert gas is formed
Implementation Method 3
an edge portion of the conductive plate tapers in a radially outward direction
Data Source
AI summary
Methods and apparatus for processing substrates are disclosed herein. In some embodiments, a substrate support to support a substrate in a processing chamber includes a dielectric insulator plate; a conductive plate supported on the dielectric insulator plate, the conductive plate comprising a top surface and a bottom surface defining a thickness between the top surface and the bottom surface, wherein an edge portion of the conductive plate tapers in a radially outward direction; and a dielectric plate comprising a substrate support surface disposed upon the top surface of the conductor plate.