Single-Switch Bias Supply for Narrow Ion Energy Control
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Solution Overview
Problem
Current plasma processing techniques struggle to achieve a narrow ion energy distribution, as sinusoidal waveforms induce broad distributions, limiting etch profile capabilities and increasing costs, inefficiencies, and affecting plasma density.
Innovation Solution
A single controlled switch and resonant circuit with a single variable voltage supply are used to control switching frequency, enabling a simplified circuit that produces a desired narrow energy distribution by repeatedly closing the switch to complete full cycles of current from zero to peak values in both directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If known techniques are used to achieve narrow ion energy distribution, then etch profile capability improves, but system becomes expensive, inefficient, and difficult to control
Solution Approach 1:
The patent combines multiple functions into a single voltage supply circuit with one controlled switch. The same circuit generates the periodic voltage pulses that control both plasma generation and ion energy distribution, eliminating the need for separate complex control systems
Solution Approach 2:
The resonant circuit automatically generates the periodic voltage waveform through its inherent resonant properties. The circuit self-regulates the pulse timing and duration based on its resonant frequency, reducing the need for complex external control mechanisms
2Manufacturing precision
If known techniques are used to achieve narrow ion energy distribution, then etch profile capability improves, but plasma density is adversely affected
Solution Approach 1:
The patent changes the voltage waveform parameters (pulse duration, repetition frequency, amplitude) to simultaneously achieve narrow ion energy distribution and maintain adequate plasma density. By optimizing these parameters, the system resolves the trade-off between ion energy control and plasma generation
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 distribution, achieving a monoenergetic ion flux with reduced complexity and cost, while maintaining optimal plasma density.
Implementation Method 1
utilizing switching frequency as a means of control together with a single controlled switch in a resonant circuit
Implementation Method 2
A first inductor is coupled between a first node of the switch and the output node and a first node of a second inductor is coupled to one of the output node or the first node of the switch
Data Source
AI summary
Bias supplies, plasma processing systems, and associated methods are disclosed. One bias supply comprises a first inductor coupled between a first node of a switch and an output node where a first node of a second inductor is coupled to one of the output node or the first node of the switch. A voltage source is coupled between a second node of the switch and a second node of the second inductor. A connection is made between the return node and one of the second node of the switch and the second node of the second inductor. The bias supply also comprises a controller configured to cause an application of the periodic voltage between the output node and the return node by repeatedly closing the switch so current through the switch completes a full cycle.