Edge Ring Voltage Waveform Control for Plasma Sheath Uniformity
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Solution Overview
Problem
In semiconductor manufacturing processes using plasma, the plasma sheath thickness variation around the edge ring of the wafer causes inefficient plasma particle incidence, leading to distorted angles and reduced etching/deposition effectiveness, and the edge ring charging issues hinder efficient process control.
Innovation Solution
A semiconductor processing apparatus with a ring voltage supply that applies a non-sinusoidal periodic waveform to the edge ring, featuring a constant positive voltage followed by a gradually increasing negative voltage, synchronizing with bias power signals to control the plasma sheath thickness and prevent edge ring charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional sinusoidal voltage is applied to the edge ring, then the plasma process can be maintained, but the plasma sheath thickness varies around the edge ring causing distorted plasma particle incidence angles and reduced process efficiency
Solution Approach 1:
The patent applies a periodic voltage waveform to the edge ring that alternates between positive and negative phases. During the positive phase, the voltage repels plasma particles from the edge ring region, effectively increasing the plasma sheath thickness in that area. During the negative phase, the voltage attracts plasma particles, decreasing the sheath thickness. This periodic modulation compensates for the naturally thinner sheath at the edge ring region, achieving uniform plasma particle incidence angles across the entire wafer surface and improving etching/deposition effectiveness.
2Productivity
If bias power is supplied to generate plasma, then the semiconductor manufacturing process can be performed, but the edge ring becomes charged which hinders efficient process control
Solution Approach 1:
The patent applies a positive voltage to the edge ring during specific phases of the periodic waveform to preemptively counteract the charging effect caused by plasma generation. This preliminary anti-action prevents charge accumulation on the edge ring by repelling plasma particles before they can deposit charge, thereby maintaining stable process control and preventing the harmful charging effect that would otherwise disrupt the manufacturing process.
3Ease of manufacture
If the plasma sheath thickness is not controlled at the edge ring, then the apparatus structure remains simple, but the plasma particle incidence becomes distorted reducing etching/deposition effectiveness
Solution Approach 1:
The patent modifies the voltage parameter applied to the edge ring from a conventional continuous sinusoidal waveform to a periodic waveform with distinct positive and negative phases. This parameter change enables dynamic control of the plasma sheath thickness at the edge ring region, compensating for the naturally thinner sheath and achieving uniform plasma particle incidence angles without requiring complex structural modifications to the apparatus.
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 ensures uniform plasma particle incidence and maintains process efficiency by adjusting the plasma sheath thickness and preventing edge ring charging, thereby improving the semiconductor manufacturing process.
Implementation Method 1
the ring voltage supply configured to supply a ring voltage to the ring electrode, the ring electrode having a non-sinusoidal periodic waveform... to control a thickness of a plasma sheath region
Implementation Method 2
When a semiconductor process using plasma is performed, radicals and ions may be formed in a chamber. The radicals and the ions may be formed by bias power supplied to the chamber.
Data Source
AI summary
A semiconductor processing apparatus includes a chamber housing, an electrostatic chuck disposed in the chamber housing, the electrostatic chuck being configured to hold a semiconductor wafer, an edge ring surrounding the electrostatic chuck, the edge ring including a ring electrode disposed within the edge ring, and a ring voltage supply configured to supply a ring voltage to the ring electrode, the ring voltage having a non-sinusoidal periodic waveform, wherein each period of the non-sinusoidal periodic waveform comprises a positive voltage applied during a first time period and a negative voltage applied during a second time period, and wherein the negative voltage has a magnitude that increases during the second time period.