PECVD Pedestal Bias Control for Wafer Arcing Suppression
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Solution Overview
Problem
Arcing between a substrate and substrate pedestal in Plasma Enhanced Chemical Vapor Deposition (PECVD) tools is a significant issue, leading to electrical breakdown and potential destruction of sensitive circuitry on semiconductor wafers, resulting in manufacturing losses and increased costs.
Innovation Solution
A CVD tool with a DC bias control system that maintains the substrate pedestal at the same DC bias voltage as the substrate, eliminating the voltage differential and thereby suppressing or preventing arcing, using an Electrostatic Chucking (ESC) power supply and a system controller to manage and adjust the bias voltage based on real-time current measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If PECVD processing is performed with RF potential applied to generate plasma, then thin film deposition is achieved, but DC bias voltage develops between substrate and pedestal causing arcing
Solution Approach 1:
The patent applies equipotentiality by maintaining the substrate pedestal at the same DC bias voltage as the substrate through active control. The DC bias control system continuously adjusts the pedestal voltage to match the substrate voltage, eliminating voltage differential and preventing arcing while allowing plasma processing to proceed
Solution Approach 2:
The patent changes the electrical parameter (DC bias voltage) of the substrate pedestal dynamically. Instead of maintaining a fixed voltage or ground potential, the pedestal voltage is actively adjusted to track and match the substrate's DC bias voltage, thereby eliminating the conditions for electrical breakdown
2Manufacturing precision
If thin films are deposited on substrates, then film thickness increases, but DC bias voltage magnitude increases leading to higher probability of electrical breakdown
Solution Approach 1:
The patent implements feedback control where the DC bias control system continuously monitors the DC bias voltage that develops on the substrate during deposition and actively adjusts the pedestal voltage to maintain equipotential conditions. This feedback mechanism ensures reliability even as film thickness and associated voltage changes evolve over time
3Productivity
If DC voltage difference exceeds threshold, then electrical breakdown occurs, but this destroys sensitive circuitry and reduces manufacturing yield
Solution Approach 1:
The patent applies preliminary anti-action by proactively preventing the voltage differential from reaching breakdown thresholds. The DC bias control system continuously counteracts the developing voltage difference between substrate and pedestal, eliminating the harmful electrical discharge before it can occur and protect sensitive circuitry
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 eliminates arcing, reducing the risk of electrical breakdown and maintaining consistent processing conditions, even as the DC bias voltage and substrate conditions change over time, thereby enhancing manufacturing yield and reducing costs.
Implementation Method 1
A Radio Frequency (RF) potential is applied between two electrodes, typically provided on the shower head and/or the substrate pedestal, to generate a plasma. Energized electrons ionize or dissociate (e.g., 'crack') reactant gasses from the plasma, creating chemically reactive radicals.
Implementation Method 2
During operation, the plasma and substrate in the processing chamber inherently develops a Direct Current (DC) bias voltage when the RF potential is applied. As a result, a non-zero DC voltage exists between the substrate and the substrate pedestal due to the resistive materials.
Implementation Method 3
The tool also includes a bias control system configured to induce a DC potential to the substrate at a deliberate target electrical potential.
Data Source
AI summary
A tool that suppresses or altogether eliminates arcing between a substrate pedestal and substrate is disclosed. The tool includes a processing chamber, a substrate pedestal for supporting a substrate within the processing chamber, and shower head positioned within the processing chamber. The shower head is arranged to dispense gas that is turned into a plasma, which develops a DC self-bias potential on the substrate surface. The tool also includes a bias control system configured to induce a DC potential to the substrate at a deliberate target electrical potential.