Plasma Processing Apparatus Ion Energy Control via Pulsed Voltage Superimposition
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Solution Overview
Problem
Conventional parallel plate type plasma processing apparatuses face challenges in finely controlling ion energy range and average substrate incident energy, leading to substrate processing issues such as shape deterioration and reduced processing anisotropy due to wide ion energy distribution, which is difficult to manage with existing high frequency and pulsed wave techniques.
Innovation Solution
A substrate plasma processing apparatus and method that superimposes a pulsed voltage with an RF voltage, allowing control of pulse width, period, and voltage value to shift and combine ion energy peaks, thereby narrowing the ion energy range and optimizing energy distribution for precise substrate processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional RF voltage alone is applied to generate plasma, then plasma generation is achieved, but ion energy range is wide causing substrate shape deterioration and reduced processing anisotropy
Solution Approach 1:
The patent combines RF voltage and pulsed voltage into a composite voltage applied to the electrode. This merging allows the system to leverage both the plasma generation capability of RF voltage and the ion energy control capability of pulsed voltage, thereby narrowing the ion energy range while maintaining effective plasma processing
Solution Approach 2:
The patent introduces periodic pulsed voltage superimposed on the continuous RF voltage. This periodic action creates distinct phases in the voltage application that control ion acceleration timing, resulting in a narrower ion energy range and improved substrate processing precision
2Productivity
If RF power is increased to increase Vdc for appropriate processing rate, then processing rate improves, but ion energy distribution widens causing corner flaws and shape deterioration
Solution Approach 1:
By applying periodic pulsed voltage superimposed on RF voltage, the system controls ion acceleration in discrete time windows. This allows maintaining high processing rates through sufficient ion flux while narrowing the ion energy range through synchronized acceleration, preventing corner flaws and shape deterioration
Solution Approach 2:
The patent changes the voltage application parameters by superimposing pulsed voltage with specific pulse width, period, and amplitude onto the RF voltage. This parameter modification enables independent control of ion energy distribution while maintaining processing rate, resolving the trade-off between productivity and precision
3Measurement precision
If conventional techniques are used to narrow ion energy range, then device complexity increases requiring multiple high frequency power sources, but ion energy control precision is needed
Solution Approach 1:
The patent merges the functions of plasma generation and ion energy control into a single electrode by applying both RF voltage and pulsed voltage to the same electrode. This eliminates the need for separate power sources and complex configurations while achieving precise ion energy control
Solution Approach 2:
The electrode serves multiple functions by receiving both RF voltage for plasma generation and pulsed voltage for ion energy control. This multi-functionality simplifies the overall system architecture while maintaining high ion energy 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
The approach effectively generates a plasma with a narrower ion energy range, enabling finer control over substrate processing, reducing shape flaws and improving processing anisotropy, even for insulating films, by utilizing the inherent characteristics of pulsed voltage superimposition to combine energy peaks and optimize ion energy usage.
Implementation Method 1
a predetermined RF voltage is applied to the RF electrode from a commercial RF power source to generate a high frequency wave of 13.56 MHz so that the intended plasma can be generated between the RF electrode and the opposing electrode
Implementation Method 2
applying a pulsed voltage to the RF electrode so as to be superimposed with the RF voltage... shift and combine ion energy peaks, thereby narrowing the ion energy range
Implementation Method 3
since the RF electrode (substrate) is charged negatively so as to be self-biased negatively (the amplitude of the electric potential: Vdc), positive ions are incident onto the substrate at high velocity by means of the negative self-bias of Vdc
Implementation Method 4
the surface reaction of the substrate is induced by utilizing the substrate incident energy of the positive ions, thereby conducting an intended plasma substrate processing such as reactive ion etching (RIE)
Data Source
AI summary
A substrate plasma processing apparatus includes a chamber of which an interior is evacuated under a predetermined vacuum condition; an RF electrode which is disposed in the chamber and configured so as to hold a substrate to be processed on a main surface thereof; an opposing electrode which is disposed opposite to the RF electrode in the chamber; an RF voltage applying device for applying an RF voltage with a predetermined frequency to the RF electrode; and a pulsed voltage applying device for applying a pulsed voltage to the RF electrode so as to be superimposed with the RF voltage.