Plasma Bias Waveform Shaping for Stable Ion Energy Control
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Solution Overview
Problem
The precision and reliability of plasma processes in semiconductor manufacturing are compromised due to the wide energy distribution of ions caused by varying bias voltages in existing voltage generators, affecting the quality of semiconductor products.
Innovation Solution
A voltage waveform generator is developed, comprising a pulse circuit and a slope circuit with inductive elements, which generates a non-sinusoidal periodic wave to control the ion energy by applying variable amplitude and direction currents to the plasma chamber, ensuring a narrow energy band distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional voltage generator is used to generate bias voltage for plasma ions, then the plasma process can be performed, but the ion energy distribution becomes wide which reduces manufacturing precision
Solution Approach 1:
The patent applies periodic pulsed voltage instead of continuous voltage to control plasma ions. The pulse circuit generates periodic voltage pulses with specific width and amplitude, creating time-varying electric fields that accelerate ions in a controlled periodic manner, resulting in narrow energy distribution while maintaining process reliability
Solution Approach 2:
The patent changes the voltage waveform parameters dynamically by adjusting pulse width, amplitude, and frequency through the controller. The slope circuit modifies the voltage transition characteristics, enabling precise control of ion acceleration profiles and energy distribution without compromising plasma process stability
2Ease of operation
If the voltage waveform is simplified to ease control, then the device complexity is reduced, but the ability to control ion energy precisely is compromised
Solution Approach 1:
The patent employs dynamic voltage waveform generation where the controller adjusts pulse width, amplitude, and frequency in real-time. The slope circuit dynamically modifies voltage transitions, enabling precise ion energy control through time-varying parameters while maintaining user-friendly operation through automated control
Solution Approach 2:
The patent introduces a slope circuit as an intermediary between the pulse circuit and plasma chamber. This intermediate stage shapes the voltage waveform by controlling the rate of voltage change, providing an additional degree of freedom for precise ion energy control without complicating the overall system operation
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 stabilizes the ion energy distribution, improving the precision and reliability of plasma processes, thereby enhancing the quality and consistency of semiconductor products.
Implementation Method 1
a pulse circuit comprising a first inductive element configured to store a first internal current
Implementation Method 2
a slope circuit comprising a second inductive element configured to store a second internal current
Implementation Method 3
a radio frequency (RF) power source configured to generate plasma ions in the chamber
Data Source
AI summary
A wafer processing apparatus includes a chamber, and a voltage waveform generator configured to accelerate plasma ions of the chamber, the voltage waveform generator includes: a pulse circuit configured to apply a chamber voltage, which is a pulse voltage, to the chamber by adjusting a chamber current applied to the chamber; and a slope circuit configured to generate a slope in an on-duty of the chamber voltage, which is the pulse voltage, and the pulse circuit includes a first inductive element configured to store a first internal current.