Divided Electrode Impedance Control for Plasma Uniformity
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Solution Overview
Problem
The uniformity of films formed on substrates during semiconductor manufacturing is compromised due to variations in electrical potential and active species distribution caused by high-frequency power and changing impedance values, limiting the control over film forming rates and pressure.
Innovation Solution
A substrate processing apparatus with a plurality of divided electrodes and impedance adjusting units, where the impedance of the electrode facing the loading port is set higher than others, allowing for independent control of electrical potentials and uniform plasma distribution across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single variable impedance electrode is used to control film forming rate, then the film forming rate can be adjusted, but the uniformity of active species distribution across the substrate deteriorates
Solution Approach 1:
The single variable impedance electrode is divided into multiple divided electrodes (first, second, third, and fourth divided electrodes) arranged at different positions on the substrate support. Each divided electrode can independently adjust its impedance, allowing localized control of active species distribution while maintaining overall film forming rate control
Solution Approach 2:
Different impedance values are applied to different divided electrodes based on their positions relative to the loading port. The electrode facing the loading port is set to a higher impedance value than other electrodes, creating non-uniform electrical potential distribution that compensates for the non-uniform plasma distribution caused by the loading port structure
2Productivity
If the impedance of the variable impedance electrode is adjusted, then the film forming rate is controlled, but the electrical potential uniformity across the substrate deteriorates due to high-frequency power effects
Solution Approach 1:
The electrode is segmented into multiple independently controllable divided electrodes, each connected to its own impedance adjusting unit. This allows independent adjustment of electrical potential at different locations to compensate for high-frequency power-induced non-uniformity
Solution Approach 2:
The impedance values of different divided electrodes are changed differently - specifically, the electrode facing the loading port is set to a higher impedance than other electrodes. This parameter differentiation compensates for the non-uniform electrical potential distribution caused by high-frequency power and loading port geometry
3Manufacturing precision
If processing pressure is adjusted to cope with parameter changes, then some uniformity can be maintained, but the control range is limited and high film forming rates cannot be achieved
Solution Approach 1:
Instead of relying solely on processing pressure adjustment, the invention introduces impedance as a new controllable parameter. By adjusting the impedance of divided electrodes, the system can achieve both high film forming rates and good uniformity that cannot be obtained by pressure adjustment alone
Solution Approach 2:
The system dynamically adjusts the impedance of different divided electrodes during the film formation process. This dynamic control allows real-time optimization of both film forming rate and uniformity, overcoming the static limitations of pressure-based control
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 enhances the uniformity of film thickness and reproducibility by ensuring consistent active species delivery, addressing the issue of uneven film formation and improving the control over film forming rates and pressure.
Implementation Method 1
a plasma generating unit configured to excite a process gas into plasma state
Data Source
AI summary
A substrate processing apparatus includes: a plasma generating unit to excite a process gas into plasma state; a process chamber where a substrate is processed using the process gas excited in plasma state; a loading port installed at a sidewall of the process chamber, wherein the substrate is passed through the loading port when the substrate is loaded into the process chamber; a substrate support supporting the substrate in the process chamber; an electrode unit installed in the substrate support and including a plurality of divided electrodes; an impedance adjusting unit electrically connected to each of the plurality of electrodes to adjust an impedance thereof; and a control unit to control the impedance of the impedance adjusting unit so as to adjust the electrical potentials of the respective electrodes of the electrode unit. The substrate processing apparatus improves the uniformity of a substrate during a substrate processing process using plasma.