Pulse-Modulated Microwave Power Control for Plasma Stability
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Solution Overview
Problem
Existing plasma processing apparatuses face challenges in stabilizing plasma and controlling microwave power effectively, particularly in achieving precise monitoring and control of pulse frequency and duty ratio during microwave pulse-modulation for plasma excitation in semiconductor manufacturing.
Innovation Solution
A plasma processing apparatus with a microwave output device that includes a generator producing pulse-modulated microwaves with adjustable power levels, directional couplers for measurement, and a controller for averaging measurement values to synchronize and control High and Low power levels, allowing for precise power control and monitoring of microwave output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If microwave power is pulse-modulated with High and Low levels for plasma excitation, then plasma stability is improved, but measurement precision of power levels deteriorates due to difficulty in recognizing power level boundaries
Solution Approach 1:
A synchronization signal is introduced as an intermediary between the pulse-modulated microwave power and the measurement system. This signal provides timing references that enable the measurement device to accurately identify and distinguish between High and Low power levels, resolving the boundary recognition problem while maintaining plasma stability benefits
Solution Approach 2:
The measurement device uses the synchronization signal to implement feedback control for identifying power level transitions. By comparing measurement timing with synchronization signal timing, the system can precisely determine when power levels switch, thereby improving measurement precision without compromising plasma stability
2Reliability
If microwave power is pulse-modulated for plasma excitation, then plasma control is improved, but control speed of microwave power deteriorates
Solution Approach 1:
The synchronization signal is generated in advance and used to pre-synchronize the measurement and control systems. This preliminary action allows the system to be ready for immediate response when power levels change, improving control speed while maintaining reliable plasma control through the synchronized timing framework
3Stability of the object's composition
If bandwidth microwave is used for plasma excitation, then plasma stability is improved, but control precision of power levels deteriorates
Solution Approach 1:
The synchronization signal acts as an intermediary that decouples the broadband microwave excitation from the precision measurement requirement. By providing external timing references, it enables precise power level control even when using bandwidth microwaves for plasma excitation, resolving the contradiction between plasma stability and control precision
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 solution enables stable plasma formation and efficient power control, allowing for easier recognition of power level boundaries and faster control of microwave power, enhancing the plasma processing efficiency in semiconductor device manufacturing.
Implementation Method 1
a microwave generator configured to generate a microwave a power of which is pulse-modulated
Implementation Method 2
configured to output a microwave for exciting a gas supplied into the chamber main body
Implementation Method 3
exciting a gas supplied into the chamber main body
Data Source
AI summary
A microwave output device includes a microwave generator configured to generate a pulse-modulated microwave; an output unit; a first directional coupler configured to output a part of a progressive wave; and a measurement device configured to determine measurement values of High and Low levels of a power of the progressive wave. The microwave generator alternately generates a first microwave having a bandwidth and a second microwave having a single frequency peak in synchronization with switching of the High level and the Low level; averages the measurement value corresponding to the first microwave with a moving average time equal to or larger than a reciprocal of a carrier pitch; averages the measurement value corresponding to the second microwave with a moving average time less than the reciprocal of the carrier pitch; and controls the powers of High and Low levels based on the averaged measurement values and set powers.