Pulse-Modulated UV Source for Plasma Ignition Control
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Solution Overview
Problem
Existing plasma processing techniques face challenges in improving plasma ignitability at low gas pressure and low microwave power conditions, which can affect etching uniformity and dimensional accuracy of semiconductor devices, and continuous ultraviolet exposure can increase wafer temperatures.
Innovation Solution
A plasma processing apparatus and method that employs a pulse-modulated ultraviolet light source controlled to apply ultraviolet rays before radio frequency power is supplied, enhancing plasma ignitability without altering processing conditions and minimizing wafer temperature increases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous ultraviolet rays are applied to improve plasma ignitability, then plasma ignitability is improved, but wafer temperature increases affecting processing dimensions
Solution Approach 1:
The patent applies periodic (pulsed) ultraviolet rays instead of continuous irradiation. The controller activates the ultraviolet light source in pulses before plasma ignition, providing sufficient energy to improve ignitability while limiting total energy input to prevent excessive wafer heating. This temporal modulation resolves the contradiction between achieving reliable plasma ignition and maintaining acceptable wafer temperature.
2Manufacturing precision
If gas pressure or microwave power is lowered to decrease plasma density for better etching uniformity, then etching uniformity is improved, but plasma ignition becomes difficult
Solution Approach 1:
The patent applies ultraviolet rays in advance before plasma ignition to pre-excite gas molecules and atoms in the processing chamber. This preliminary action creates a population of excited species that lowers the ignition threshold, enabling reliable plasma formation even at reduced gas pressure and microwave power settings where etching uniformity is optimized.
Solution Approach 2:
The patent changes the physical state of gas molecules through ultraviolet excitation, transitioning them from ground state to excited states. This parameter change in molecular energy levels facilitates easier plasma ignition by reducing the energy barrier for electron collision ionization, allowing ignition at lower microwave power and gas pressure conditions.
3Manufacturing precision
If microwave power is reduced to maintain processing conditions, then processing quality is maintained, but plasma ignition reliability decreases
Solution Approach 1:
The patent introduces ultraviolet radiation as an intermediary mechanism to bridge the gap between reduced microwave power and reliable plasma ignition. The ultraviolet light acts as a mediator that provides an alternative pathway for energy input to excite gas molecules, compensating for the reduced microwave power while maintaining processing quality parameters.
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
The approach effectively improves plasma ignitability and reduces dimensional influences on processed workpieces, achieving efficient plasma generation and processing while maintaining desired conditions.
Implementation Method 1
supplied ultraviolet rays act so as to excite atoms or molecules in plasma and increase the energy of the atoms or molecules
Implementation Method 2
a radio frequency power supply configured to supply radio frequency power that generates plasma
Implementation Method 3
continuous application of ultraviolet rays to wafers might affect processing dimensions due to an increase in the temperature of wafers
Data Source
AI summary
A plasma processing apparatus includes: a processing chamber in which a sample is subjected to plasma treatment; a radio frequency power supply configured to supply radio frequency power that generates plasma; a sample stage on which the sample is placed; and an ultraviolet light source configured to apply an ultraviolet ray. The apparatus further includes a controller configured to control the ultraviolet light source such that before the radio frequency power is supplied into the processing chamber, a pulse-modulated ultraviolet ray is applied into the processing chamber.