Capacitive Coupling Plasma Control for Uniformity
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Solution Overview
Problem
Plasma uniformity remains unsatisfactory in capacitive coupling type plasma processing apparatuses, even with the use of higher frequency RF power, due to inadequate control over the application timing of DC voltage in generating stable and good plasma.
Innovation Solution
A plasma processing apparatus and method that includes a control section to manage the application of DC voltage in conjunction with RF power, ensuring the DC voltage reaches a set value only after the RF power is initiated, preventing abnormal electric discharge and promoting stable plasma generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If DC voltage is applied in addition to RF power to control plasma density uniformity, then plasma uniformity is improved, but plasma stability deteriorates due to inadequate control over application timing
Solution Approach 1:
The control section initiates RF power application before DC voltage application, creating a preparatory plasma environment. This preliminary RF heating ensures that when DC voltage is subsequently applied, the plasma is already in a stable state, preventing abnormal discharge and achieving both uniformity and stability
2Speed
If DC voltage is applied before RF power, then plasma generation is accelerated, but abnormal electric discharge occurs causing plasma instability
Solution Approach 1:
The system applies RF power in advance to pre-ionize and heat the gas, creating a stable plasma foundation before DC voltage is applied. This sequence prevents the harmful effect of applying DC to cold gas while still achieving rapid plasma generation through the combined effect
3Quantity of substance
If higher frequency RF power is used to generate high density plasma, then plasma density is improved, but plasma uniformity deteriorates
Solution Approach 1:
The system changes the electrical parameters by applying DC voltage to the electrode in addition to RF power. This parameter modification alters the plasma characteristics, enabling high density plasma generation while simultaneously improving uniformity through the combined electric field effects
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 generates stable and uniform plasma, enhancing plasma etching processes by preventing damage to the substrate and maintaining plasma integrity, thus improving the precision and effectiveness of semiconductor manufacturing.
Implementation Method 1
an RF (radio frequency) is applied to one of the electrodes to form an RF electric field between the electrodes. The process gas is ionized into plasma by the RF electric field
Implementation Method 2
an upper electrode is supplied with a DC (direct current) voltage, as well as an RF power with a frequency of 27 MHz or more, to control plasma so as to uniformize the plasma density
Data Source
AI summary
A plasma processing apparatus includes a process container configured to accommodate a target substrate and to be vacuum-exhausted. A first electrode and a second electrode are disposed opposite each other within the process container. A process gas supply unit is configured to supply a process gas into the process container. An RF power supply is configured to apply an RF power to the first electrode or second electrode to generate plasma of the process gas. A DC power supply is configured to apply a DC voltage to the first electrode or second electrode. A control section is configured to control the RF power supply and the DC power supply such that the DC power supply causes the DC voltage applied therefrom to reach a voltage set value, when or after the RF power supply starts applying the RF power.