Impedance Matching Power Compensation for Uniform Plasma Etching
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Solution Overview
Problem
Semiconductor processing tools face challenges in maintaining uniformity due to chamber-to-chamber variations in parasitic power losses, leading to inconsistent RF power delivery and etch rates in plasma etching processes.
Innovation Solution
A chamber-matching power compensation scheme is implemented using a current probe to measure real-time parasitic power losses, adjusting the RF generator's power set point through a modified control loop, ensuring consistent power delivery across different plasma chambers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chamber-matching power compensation is implemented, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the measured coupled power is compared against the target power level, and the RF generator power setpoint is adjusted based on the difference. This closed-loop control continuously compensates for parasitic power losses, ensuring consistent etch rates across different chambers while managing complexity through automated feedback rather than manual calibration.
Solution Approach 2:
The system performs self-calibration by automatically measuring its own coupled power and adjusting its power delivery accordingly. The chamber-matching network autonomously identifies and compensates for its own parasitic losses without requiring external intervention, reducing operational complexity while maintaining precision.
2Reliability
If real-time power measurement and adjustment is implemented, then reliability is improved, but loss of time increases
Solution Approach 1:
The system performs preliminary characterization of each chamber's parasitic power losses during setup, storing this information for use during production. This pre-characterization allows the system to start with an informed power setpoint, reducing the time needed for real-time adjustments while maintaining reliable, repeatable processing.
Solution Approach 2:
The power compensation operates continuously during plasma processing, constantly measuring coupled power and adjusting the RF generator output without interrupting the etch process. This continuous adjustment maintains reliability while minimizing time loss by avoiding stop-start calibration procedures.
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 achieves uniform etch rates and deposition rates across multiple substrates by compensating for parasitic power losses, enhancing processing repeatability and stability in semiconductor processing tools.
Implementation Method 1
A value of an equivalent series resistance (ESR) of the bias matching network and entire assembly is calculated by performing a linear regression on the measured RMS current squared and power delivered by the RF generator
Implementation Method 2
The RF generator is turned on to provide RF power to the plasma chamber via the match and the transmission line
Implementation Method 3
When the process gas is ignited by the RF power, plasma is stricken in the plasma chamber
Data Source
AI summary
Systems and methods for compensating for radio frequency (RF) power loss are described. One of the methods includes conducting a no plasma test to determine a resistance associated with an output of an impedance matching circuit. After conducting the no plasma test, a substrate is processed in a plasma chamber. During processing of the substrate, power loss associated with the output of the impedance matching circuit is determined. The power loss is used to determine an amount of power to be delivered by an RF generator. The amount of power delivered is adjusted until the power loss is stabilized. The stabilization of the power loss facilitates uniform process of the substrate and additional substrates in the plasma chamber.