Dielectric Window Cylindrical Lower Portion Plasma Uniformity

Solution Overview

Problem

The existing dielectric windows in substrate processing systems limit the tunability and uniformity of RF power distribution in plasma, leading to issues such as global etch tilting during high aspect ratio etching due to their flat plasma-facing surfaces.

Innovation Solution

A dielectric window with a pi-shaped cross-section, comprising a flat upper portion and a cylindrical lower portion, which separates the plasma into two isolated zones, allowing for improved control and tunability of RF power distribution by aligning the outer diameter of the lower portion with the gap between inner and outer coils.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a flat dielectric window is used, then the structure is simple and easy to manufacture, but the RF power distribution uniformity deteriorates

Engineering Contradiction:

Improveease of manufactureVSAvoidRF power distribution uniformity

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The dielectric window incorporates a curved lower surface instead of a flat surface, creating a spherical or dome-shaped geometry that focuses and distributes RF power more uniformly across the plasma chamber. This curvature modification directly addresses the non-uniform RF power distribution problem while maintaining manufacturing feasibility through standard glass forming processes.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The invention transitions from a two-dimensional flat surface to a three-dimensional curved surface by adding vertical curvature to the dielectric window. This dimensional change allows the RF fields to be distributed more evenly in the vertical dimension, thereby improving overall uniformity across the plasma processing chamber.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Manufacturing precision

If a curved dielectric window is used, then the RF power distribution uniformity is improved, but the manufacturing complexity increases

Engineering Contradiction:

ImproveRF power distribution uniformityVSAvoidstructural complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The dielectric window incorporates a curved lower surface instead of a flat surface, creating a spherical or dome-shaped geometry that focuses and distributes RF power more uniformly across the plasma chamber. This curvature modification directly addresses the non-uniform RF power distribution problem while maintaining manufacturing feasibility through standard glass forming processes.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The invention modifies the geometric parameters of the dielectric window by introducing a specific curvature radius and dome height. These parameter changes optimize the RF power distribution while allowing the use of standard manufacturing processes, thus balancing performance improvement with manufacturing simplicity.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If the dielectric window material is changed to improve plasma uniformity, then the processing precision is improved, but the cost and manufacturing difficulty increase

Engineering Contradiction:

Improveplasma uniformityVSAvoidease of manufacture

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The invention modifies the geometric parameters of the dielectric window by introducing a specific curvature radius and dome height. These parameter changes optimize the RF power distribution while allowing the use of standard manufacturing processes, thus balancing performance improvement with manufacturing simplicity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The dielectric window is constructed from a composite structure combining a curved glass dome with a metallic flange assembly. This composite design allows the glass portion to be formed using standard glass forming processes while the metal flange provides mechanical mounting features, thus maintaining ease of manufacture while achieving the desired plasma uniformity.

Inventive Principle:

Principle #40Composite materials

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 design enhances plasma uniformity and tunability, reducing global etch tilting and improving processing characteristics like etching and deposition rates by physically separating the plasma into distinct zones.

Implementation Method 1

The dielectric window allows the RF signal to be transmitted from the TCP reactor coils into the interior of the processing chamber

Methodology Applied

Scientific EffectRF signal transmission: Electromagnetic Induction

Implementation Method 2

The RF signal excites gas molecules within the processing chamber to generate plasma

Methodology Applied

Scientific EffectPlasma generation: Electromagnetic Induction

Data Source

PatentUS20230126058A1Dielectric window for substrate processing chamber

Publication Date: 2023.04.27 LAM RES CORP

AI summary

A lid assembly for a processing chamber in a substrate processing system includes a dielectric window. The dielectric window includes an upper portion having flat upper and lower surfaces. The lower surface is a plasma-facing surface of the dielectric window. A lower portion of the dielectric window is cylindrical and extends downward from the lower surface and an outer diameter of the lower portion at least one of is aligned with a gap between inner and outer coils arranged above the dielectric window and overlaps one of the inner and outer coils.