Focus Ring Geometry for Precise Chuck Alignment and Plasma Uniformity

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Solution Overview

Problem

Existing semiconductor fabrication processes face challenges in aligning the focus ring with the electrostatic chuck structure, leading to deviations in substrate processing and plasma distribution, which affects the uniformity and quality of semiconductor devices.

Innovation Solution

A focus ring design with a central axis aligned to improve substrate alignment, featuring a top surface with a smaller inner diameter and a bottom surface with a larger inner diameter, and inner lateral surfaces that form specific angles with the central axis, allowing for precise alignment with the electrostatic chuck structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a conventional focus ring design is used, then the structure is simple, but the alignment with the electrostatic chuck structure is inaccurate leading to substrate deviation

Engineering Contradiction:

Improvealignment precisionVSAvoidfocus ring structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The focus ring employs an asymmetric conical configuration where the inner lateral surface forms a specific angle (e.g., 5-10 degrees) with the central axis. This asymmetric geometry enables precise alignment with the electrostatic chuck structure while maintaining manufacturing feasibility, resolving the contradiction between alignment precision and structural simplicity.

Inventive Principle:

Principle #4Asymmetry

2Manufacturing precision

If the focus ring is positioned closer to the electrostatic chuck structure, then plasma distribution is improved, but thermal expansion issues arise

Engineering Contradiction:

Improveplasma distribution uniformityVSAvoidthermal stability

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The focus ring utilizes a conical configuration with controlled inner diameter variation along its length, creating optimal spacing between the focus ring and electrostatic chuck structure. This geometric parameter optimization enables improved plasma distribution while maintaining sufficient clearance to accommodate thermal expansion, resolving the contradiction between plasma uniformity and thermal stability.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP4307339A1Focus ring, substrate processing apparatus including the same, and semiconductor fabrication method using the same

Publication Date: 2024.01.17 SAMSUNG ELECTRONICS CO LTD

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AI summary

A substrate processing apparatus includes a focus ring, the focus ring includes a central axis that extends in a first direction, a top surface having a first inner diameter, a bottom surface having a second inner diameter that is smaller than the first inner diameter, and an inner lateral surface between the top surface and the bottom surface, the inner lateral surface including a first inner lateral surface and a second inner lateral surface, where the second inner lateral surface extends downward from the first inner lateral surface and a first angle between the first inner lateral surface and a line corresponding to the first direction is different from a second angle between the second inner lateral surface and the line corresponding to the first direction.