Cascade Waveform Generator for Plasma Ion Energy Control

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Solution Overview

Problem

Precise control of plasma reactions in semiconductor manufacturing is challenging due to difficulties in controlling ion energy distribution during the etching process, leading to suboptimal etching performance and selectivity.

Innovation Solution

A designed waveform generator is used in a plasma processing apparatus, combining a square wave and a variable waveform to control ion energy, with the waveforms generated by pulse and slope modules connected in a cascade manner, allowing for precise adjustment of ion energy levels and distributions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a conventional single waveform generator is used to control plasma, then the device structure is simple, but the ion energy distribution cannot be precisely controlled

Engineering Contradiction:

Improveion energy distribution control precisionVSAvoidwaveform generator structure complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The waveform generator is divided into multiple independent modules: a first waveform generator producing a square wave and a second waveform generator producing a variable waveform. Each module has a specific function, and their outputs are combined to achieve precise ion energy distribution control that neither module could achieve alone.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent combines the output signals from the first waveform generator (square wave) and the second waveform generator (variable waveform) to create a composite waveform. This merged signal enables precise control of ion energy distribution by leveraging the strengths of both waveform types simultaneously.

Inventive Principle:

Principle #5Merging (Combining)

2Manufacturing precision

If only a square wave is applied to control plasma, then the voltage level is stable, but the ion energy distribution uniformity is poor

Engineering Contradiction:

Improveion energy distribution uniformityVSAvoidwaveform control complexity

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The variable waveform generator introduces different voltage characteristics at different time points within the waveform cycle. This creates local variations in voltage that optimize ion energy distribution at different stages of the plasma process, improving overall uniformity while maintaining operational control.

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If a complex waveform is generated using a single generator, then the waveform flexibility is high, but the device reliability decreases

Engineering Contradiction:

Improveetching performance precisionVSAvoidsystem reliability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

By segmenting the waveform generation function into two separate generators, each handling a specific aspect of the waveform (square wave for voltage level stability, variable waveform for distribution shaping), the system achieves complex waveform control while improving reliability through functional separation and reduced complexity in each individual component.

Inventive Principle:

Principle #1Segmentation

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 enhances etching performance by improving etching rate and selectivity, reducing bowing phenomena and achieving more uniform ion energy distribution, thereby improving the overall semiconductor manufacturing process.

Implementation Method 1

at least one first signal generator including a first switching device and configured to generate a square wave having a constant voltage level during an on-period of the first switching device

Methodology Applied

Scientific EffectSquare wave generation:

Implementation Method 2

at least one second signal generator including a second switching device and configured to control a transition period of the second switching device to generate a variable waveform having a variable voltage level during the transition period of the second switching device

Methodology Applied

Scientific EffectVariable waveform generation:

Implementation Method 3

The at least one first signal generator and the at least one second signal generator are connected to each other in a cascade manner

Methodology Applied

Scientific EffectSignal superposition:

Implementation Method 4

a second power generator configured to apply a second signal to the bottom electrode to control an ion energy of the plasma

Methodology Applied

Scientific EffectIon energy control:

Data Source

PatentUS10474184B2Designed waveform generator for semiconductor equipment, plasma processing apparatus, method of controlling plasma processing apparatus, and method of manufacturing semiconductor device

Publication Date: 2019.11.12 SAMSUNG ELECTRONICS CO LTD

AI summary

A designed waveform generator includes at least one first signal generator including a first switching device and generating a square wave having a constant voltage level during an on-period of the first switching device and at least one second signal generator including a second switching device and controlling a transition period of the second switching device to generate a variable waveform having a variable voltage level during the transition period of the second switching device. The at least one first signal generator and the at least one second signal generator are connected to each other in a cascade manner.