Bipolar Electrostatic Chuck Layout for Uniform Edge Plasma
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Solution Overview
Problem
Conventional substrate support systems in semiconductor manufacturing experience temperature non-uniformity and film thickness issues due to uneven current flow, leading to hot spots and film non-uniformity, with existing solutions failing to provide adequate plasma uniformity and protection from DC plasma and electrical discharge.
Innovation Solution
The substrate support assemblies incorporate a bipolar electrode configuration with carefully controlled orientations and distances between electrodes, allowing for a self-induced DC voltage on the outer electrode without requiring a separate DC power supply, enhancing RF electrode configurations to achieve uniform plasma deposition and reduce DC plasma generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional substrate support systems use standard electrode configurations, then the system structure is simple, but temperature non-uniformity and film thickness issues occur due to uneven current flow
Solution Approach 1:
The electrode system is segmented into multiple bipolar electrodes (first bipolar electrode, second bipolar electrode) with distinct functions and positions. The first bipolar electrode is coupled with DC power supply for chucking, while the second bipolar electrode is RF-powered for plasma generation. This segmentation allows independent control of chucking force and plasma uniformity, resolving the contradiction between manufacturing precision and device complexity.
Solution Approach 2:
Different regions of the substrate support are assigned different electrode characteristics. The first bipolar electrode provides strong chucking force at the substrate center, while the second bipolar electrode provides uniform plasma distribution at the substrate edge. This local quality differentiation ensures both central adhesion and edge plasma uniformity, improving film thickness uniformity without excessive complexity.
2Reliability
If RF power is applied to the outer electrode without DC floating, then the electrode configuration is simpler, but DC plasma and electrical discharge occur causing substrate damage
Solution Approach 1:
A mesh is introduced as an intermediary component between the RF power supply and the outer electrode. The mesh is positioned at a controlled distance (0.6 mm to 8 mm) from the outer electrode, allowing RF power to be coupled to the electrode while the electrode itself remains DC-floated. This intermediary structure enables safe RF operation without direct DC connection, preventing electrical discharge while maintaining system reliability.
Solution Approach 2:
The outer electrode is designed to be DC-floated, meaning it does not require a separate DC power supply connection. Instead, it self-adjusts its DC potential through capacitive coupling with the mesh and the plasma environment. This self-service mechanism eliminates the need for additional DC power supplies while preventing DC plasma generation, improving reliability without increasing device complexity.
3Use of energy by moving object
If the distance between mesh and outer electrode is small, then RF coupling is more efficient, but the risk of electrical discharge and DC plasma increases
Solution Approach 1:
The distance between the mesh and the outer electrode is precisely controlled within the range of 0.6 mm to 8 mm. This parameter optimization balances two competing requirements: smaller distances improve RF power coupling efficiency through stronger capacitive coupling, while larger distances reduce electrical discharge risk. The specified range represents the optimal compromise where sufficient RF power transfer is achieved without creating hazardous discharge conditions.
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 provides improved film thickness uniformity and reduced risk of substrate damage by minimizing temperature non-uniformity and electrical discharge, while maintaining uniform plasma deposition across the wafer, including edge regions.
Implementation Method 1
an annular electrode disposed about the first bipolar electrode, where the annular electrode is DC floated and RF powered and exhibits an induced DC current
Implementation Method 2
an electrostatic chuck body defining a substrate support surface that defines a substrate seat
Data Source
AI summary
Substrate support assemblies may include an electrostatic chuck body defining a substrate support surface that defines a substrate seat. Assemblies may include a support stem coupled with the electrostatic chuck body. Assemblies may include a first bipolar electrode embedded within the electrostatic chuck body. Assemblies may include a second bipolar electrode embedded within the electrostatic chuck body radially inward of at least a portion of the first bipolar electrode and coaxial with the first bipolar electrode. Assemblies may include an annular electrode disposed about the first bipolar electrode, where the annular electrode is DC floated and RF powered and exhibits an induced DC current.