Electrostatic Chuck Plasma Control for Uniform Etching
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Solution Overview
Problem
Existing semiconductor manufacturing processes face challenges in uniformly etching films on substrates due to the inability to precisely control plasma characteristics, particularly the sheath thicknesses, which affect the uniformity of the etching process.
Innovation Solution
A device and method for controlling plasma characteristics by obtaining an equivalent circuit from a non-sinusoidal generator to apply a plasma control voltage to an electrostatic chuck, using an RF power supply unit to generate and control plasma, and adjusting sheath thicknesses based on the equivalent circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma generation methods are used, then plasma is generated in the processing chamber, but the sheath thickness cannot be precisely controlled leading to non-uniform etching
Solution Approach 1:
The patent applies parameter changes by introducing a non-sinusoidal voltage signal with specific harmonic components (fundamental frequency and third harmonic) to the electrostatic chuck. This changes the plasma characteristics by controlling the sheath thickness through voltage parameter modulation, enabling precise control of plasma behavior to achieve uniform etching across the substrate surface.
Solution Approach 2:
The patent implements feedback control by measuring the actual voltage and current in the plasma circuit, calculating the equivalent circuit parameters (resistance and capacitance), and using this information to adjust the non-sinusoidal voltage signal. This closed-loop feedback mechanism ensures precise control of plasma sheath thickness and maintains etching uniformity.
2Reliability
If only sinusoidal voltage is applied to the electrostatic chuck, then the system is simple to operate, but plasma characteristics cannot be precisely controlled
Solution Approach 1:
The patent uses periodic non-sinusoidal voltage signals with specific frequency components (fundamental and third harmonic) applied to the electrostatic chuck. This periodic action with controlled waveform shape enables precise plasma characteristic control while maintaining a manageable system complexity through standardized signal generation techniques.
3Measurement precision
If the equivalent circuit is not considered, then the control system is simpler, but the sheath thickness cannot be accurately determined
Solution Approach 1:
The patent replaces direct physical measurement of sheath thickness with an electrical measurement approach. By measuring voltage and current in the equivalent circuit and calculating the capacitance, the system indirectly determines sheath thickness without requiring complex physical measurement devices, thus achieving high measurement precision with manageable system complexity.
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 solution enables uniform etching of films on substrates by effectively controlling plasma sheath thicknesses, ensuring consistent and precise film removal during the etching process.
Implementation Method 1
a power supply unit applying voltage to the electrostatic chuck, the power supply unit including an RF power supply unit applying a plasma generation voltage for generating plasma
Implementation Method 2
a non-sinusoidal generator applying a plasma control voltage for controlling the characteristics of the plasma generated
Implementation Method 3
an electrostatic chuck installed in a lower side of the processing space
Data Source
AI summary
A device for controlling plasma characteristics includes one or more processors, and a storage medium storing computer-readable instructions. The computer-readable instructions, when executed by the one or more processors, are configured to cause the one or more processors to obtain an equivalent circuit viewed from a non-sinusoidal generator for applying a plasma control voltage to an electrostatic chuck provided in a processing space of a processing chamber, and to control characteristics of plasma generated in the processing space based on the equivalent circuit obtained. The characteristics of the plasma include at least one of a first sheath thickness from a substrate to the plasma and a second sheath thickness from a shower head spraying process gas into the processing space to the plasma.