Variable Capacitor for Plasma Ion Energy Control
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Solution Overview
Problem
Current plasma etching processes in semiconductor device fabrication lack precise control over ion energy and angular distributions, which affects the precision and efficiency of material removal during integrated circuit formation.
Innovation Solution
Incorporating a variable capacitor within the RF power transmission path to a bias electrode, in conjunction with an impedance matching circuit and an RF power supply operating in a pulsed mode, to control the rate of DC bias voltage buildup on the substrate, thereby influencing ion energy and angular distributions within the plasma.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etching processes are used, then material removal is achieved, but precise control over ion energy and angular distributions is lacking
Solution Approach 1:
The patent applies dynamics by making the capacitor value variable rather than fixed. The variable capacitor allows the impedance matching circuit to adapt dynamically to changing plasma conditions, enabling precise control of ion energy and angular distributions while maintaining system stability through real-time adjustment.
Solution Approach 2:
The patent changes physical parameters by introducing a variable capacitor that can adjust its capacitance value. This parameter change enables control over the rate of DC bias voltage buildup, which directly influences ion energy and angular distributions in the plasma, thereby achieving precise manufacturing control.
2Manufacturing precision
If RF power is continuously applied to the bias electrode, then DC bias voltage is maintained on the substrate, but control over ion energy distribution is limited
Solution Approach 1:
The patent applies periodic action by pulsing the RF power to the bias electrode rather than applying it continuously. This pulsed RF power, combined with the variable capacitor, creates controlled DC bias voltage buildup during each pulse, enabling precise control over ion energy distribution while maintaining ease of operation through programmable pulse parameters.
Solution Approach 2:
The variable capacitor acts as an intermediary between the pulsed RF power source and the bias electrode. It mediates the energy transfer, controlling the rate of DC bias voltage buildup during each RF pulse, thereby providing precise control over ion energy distribution while simplifying the overall process control.
3Adaptability or versatility
If a fixed capacitor is used in the RF power transmission path, then impedance matching is achieved, but adaptability to different processing conditions is reduced
Solution Approach 1:
The patent replaces the fixed capacitor with a variable capacitor in the RF power transmission path. This dynamic component allows the impedance matching circuit to adapt to different processing conditions by adjusting its capacitance value, thereby enhancing process adaptability without significantly increasing circuit complexity.
Solution Approach 2:
The variable capacitor provides multi-functionality by serving both as an impedance matching element and as a control mechanism for DC bias voltage buildup rate. This single component achieves multiple functions, enhancing process adaptability while avoiding the need for separate control circuits.
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 allows for precise control of ion energy and angular distributions, enhancing the precision and efficiency of material removal during plasma processing, enabling better control over the plasma processing results on semiconductor substrates.
Implementation Method 1
setting a capacitance of the variable capacitor to control a rate at which a direct current (DC) bias voltage builds up on a substrate present above the bias electrode during each pulse of RF power
Implementation Method 2
an ion energy distribution and an ion angular distribution within a plasma exposed to an electromagnetic field emanating from the substrate
Implementation Method 3
operating an RF power supply in a pulsed mode to transmit pulses of RF power through the RF power transmission path to the bias electrode
Implementation Method 4
The plasma etching process involves generation of a plasma, including reactive constituents such as radicals and ions, and exposure of the substrate to the radicals and ions of the plasma
Data Source
AI summary
A variable capacitor is provided within a radiofrequency (RF) power transmission path to a bias electrode, in addition to an impedance matching circuit provided within the RF power transmission path to the bias electrode. An RF power supply is operated in a pulsed mode to transmit pulses of RF power through the RF power transmission path to the bias electrode. A capacitance of the variable capacitor is set to control a rate at which a DC bias voltage builds up on a substrate present above the bias electrode during each pulse of RF power. The rate at which the DC bias voltage builds up on the substrate controls an ion energy distribution and an ion angular distribution within a plasma exposed to an electromagnetic field emanating from the substrate.