Plasma Reactor Power Applicator Tilt for Etch Uniformity

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Solution Overview

Problem

In semiconductor device fabrication, maintaining uniform plasma etch rates across large workpieces is challenging due to asymmetrical plasma ion density distributions caused by non-symmetrical reactor chamber configurations and vacuum pump placement, which conventional control features are unable to fully correct.

Innovation Solution

A plasma reactor with a tiltable and rotatable outer plasma source power applicator and adjustable inner applicator, allowing for transformation of asymmetrical etch rate distributions into symmetrical ones, followed by fine-tuning to achieve uniformity through vertical translation and RF power adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional symmetrical control features are used to adjust plasma distribution, then the device structure remains simple and easy to manufacture, but the ability to correct asymmetrical non-uniformities is insufficient

Engineering Contradiction:

Improveuniformity of plasma distributionVSAvoidcapability to correct asymmetrical non-uniformities

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The patent applies asymmetry by introducing an asymmetrical mass (lead weight) attached to the wafer support pedestal at a specific radial position. This asymmetrical mass creates a controlled asymmetrical plasma distribution pattern that compensates for the inherent asymmetries in the reactor chamber (such as vacuum pump placement), thereby enabling uniform plasma distribution across the wafer surface despite the asymmetrical chamber configuration.

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

The patent applies local quality by positioning the asymmetrical mass at a specific radial location on the wafer support pedestal rather than distributing mass uniformly. This localized asymmetrical feature creates a targeted plasma distribution correction in the specific region where asymmetry occurs, allowing precise control over plasma uniformity without modifying the entire chamber structure.

Inventive Principle:

Principle #3Local quality

2Device complexity

If the vacuum pump is placed at a specific location in the pumping annulus, then the chamber structure is simplified, but asymmetrical plasma ion distribution occurs across the workpiece

Engineering Contradiction:

Improvechamber structureVSAvoidplasma ion distribution uniformity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #4Asymmetry

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 effectively transforms asymmetrical etch rate distributions into symmetrical and ultimately uniform distributions across the workpiece, enabling precise correction of non-uniformities and improving plasma processing uniformity.

Implementation Method 1

the plasma source power level (which primarily determines plasma ion density and dissociation)

Methodology Applied

Scientific EffectRF power: Electromagnetic Induction

Implementation Method 2

A plasma-enhanced etch process typically involves simultaneous competing processes of deposition and etching

Methodology Applied

Scientific EffectPlasma: Plasma

Implementation Method 3

tilt apparatus supporting at least the outer applicator portion and capable of tilting at least the outer applicator portion about a radial axis perpendicular to the axis of symmetry

Methodology Applied

Scientific EffectMechanical tilting:

Implementation Method 4

elevation apparatus for changing the location of the inner and outer portions relative to one another along the vertical axis of symmetry

Methodology Applied

Scientific EffectMechanical translation:

Data Source

PatentUS7431797B2Plasma reactor with a dynamically adjustable plasma source power applicator

Publication Date: 2008.10.07 APPLIED MATERIALS INC

AI summary

A plasma reactor for processing a workpiece includes a process chamber having an enclosure including a ceiling and having a vertical axis of symmetry generally perpendicular to the ceiling, a workpiece support pedestal inside the chamber and generally facing the ceiling, process gas injection apparatus coupled to the chamber and a vacuum pump coupled to the chamber. The reactor further includes a plasma source power applicator overlying the ceiling and having a radially inner applicator portion and a radially outer applicator portion, and RF power apparatus coupled to the inner and outer applicator portions, and tilt apparatus supporting at least the outer applicator portion and capable of tilting at least the outer applicator portion about a radial axis perpendicular to the axis of symmetry and capable of rotating at least the outer applicator portion about the axis of symmetry. The reactor can further include elevation apparatus for changing the location of the inner and outer portions relative to one another along the vertical axis of symmetry. In a preferred embodiment, the elevation apparatus includes a lift actuator for raising and lowering the inner applicator portion along the vertical axis of symmetry.