Pulsed Microwave Plasma for Silicon Oxide Film Formation
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Solution Overview
Problem
Plasma damage and reduced oxidation rate are issues in forming silicon oxide films using plasma processes, particularly due to intense ultraviolet light-emission from OH radicals, which degrades film quality and reduces the oxidation rate.
Innovation Solution
A plasma processing method using pulsated electromagnetic waves, such as microwaves, to control light-emission intensity in the ultraviolet region, reducing plasma damage while maintaining a sufficient oxidation rate by adjusting pulse conditions like frequency and duty ratio, and using gases like rare gases, oxygen, and hydrogen.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If plasma is used to form silicon oxide film, then low-temperature film formation is achieved, but plasma damage occurs due to intense ultraviolet light-emission from OH radicals
Solution Approach 1:
The patent applies periodic action by using pulsed microwave plasma instead of continuous plasma. The microwave power is supplied in pulses with a duty ratio of 10-90%, creating periodic plasma generation that allows the plasma to be formed and then partially decay before the next pulse. This periodic operation reduces the accumulation of OH radicals and their associated ultraviolet light-emission, thereby reducing plasma damage while maintaining low-temperature film formation capability.
2Object-affected harmful factors
If ultraviolet light-emission in plasma is suppressed, then plasma damage is reduced, but oxidation rate decreases
Solution Approach 1:
The periodic pulsed plasma operation allows for temporal separation of oxidation and damage-reduction phases. During the plasma on-time, oxidation occurs through OH radical action. During the off-time, OH radicals decay and ultraviolet light-emission is reduced, minimizing plasma damage. This periodic cycle enables both oxidation progress and damage reduction to occur sequentially, resolving the contradiction between maintaining high oxidation rate and reducing plasma damage.
Solution Approach 2:
The patent changes the temporal parameters of plasma operation by introducing pulse width and duty ratio control. By optimizing these parameters, the system achieves a balance where sufficient oxidation occurs during the plasma on-period while the off-period allows OH radical concentration to decrease, reducing ultraviolet light-emission intensity and plasma damage. This parameter optimization enables simultaneous achievement of both goals.
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 method effectively suppresses ultraviolet light-emission, minimizing plasma damage and maintaining a high oxidation rate, resulting in improved film quality and yield in semiconductor manufacturing.
Implementation Method 1
forming a silicon oxide film by oxidizing silicon by action of plasma on a target object in a process chamber of a plasma processing apparatus, while generating the plasma by pulsated electromagnetic waves
Implementation Method 2
in the case of forming an oxide film using gas plasma containing hydrogen and oxygen, the plasma causes intense light-emission in the ultraviolet region due to OH radicals
Data Source
AI summary
Pulsated microwaves are supplied to a wave guide tube from a microwave generation unit through a matching circuit. The microwaves are supplied through an inner conductor to a planar antenna member. The microwaves are radiated from the planar antenna member through a microwave transmission plate into space above a wafer within a chamber. An electromagnetic field is formed in the chamber by pulsated microwaves radiated into the chamber from the planar antenna member through the microwave transmission plate, turning an Ar gas, H2 gas and O2 gas into plasma to form an oxide film on the wafer.