Tiltable RF Inductive Source for Plasma Etch Skew Correction

Solution Overview

Problem

Existing plasma etch processes in microelectronic circuit fabrication face challenges in achieving uniform etch rate distribution across semiconductor wafers due to asymmetrical 'skew' non-uniformities, which are not effectively corrected by current radial uniformity correction methods.

Innovation Solution

A plasma reactor design featuring a floating support plate with axially movable arms and motors, allowing for independent tilt and rotation adjustments to correct skew non-uniformities by optimizing the position of RF plasma source power applicators, combined with a control system to determine and implement the necessary tilt angles for skew correction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single overhead RF coil antenna is used, then the device complexity is low, but the etch rate distribution uniformity deteriorates due to radial non-uniformity and skew non-uniformity

Engineering Contradiction:

Improvecoil antenna structureVSAvoidetch rate distribution uniformity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The single overhead RF coil antenna is divided into multiple concentric coil antennas (e.g., inner and outer coils) that can be independently powered with different RF power levels. This segmentation allows independent control of plasma generation in different radial zones, enabling correction of radial non-uniformity in etch rate distribution while maintaining a relatively simple overall structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a tiltable support structure that allows the overhead RF coil antenna assembly to be dynamically adjusted in angle relative to the workpiece. This dynamic positioning capability enables correction of skew non-uniformities by optimizing the angular orientation of the coils, thereby improving etch rate uniformity without increasing the number of coils or RF power sources.

Inventive Principle:

Principle #15Dynamics

2Manufacturing precision

If multiple concentric RF coil antennas with independent power control are used, then radial non-uniformity is corrected, but the device complexity increases and skew non-uniformity remains uncorrected

Engineering Contradiction:

Improveradial etch rate uniformityVSAvoidmultiple RF power sources

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent introduces a tiltable support structure that allows the overhead RF coil antenna assembly to be dynamically adjusted in angle relative to the workpiece. This dynamic positioning capability enables correction of skew non-uniformities by optimizing the angular orientation of the coils, thereby improving etch rate uniformity without increasing the number of coils or RF power sources.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If the RF coil antenna is fixed in position, then the device complexity is low, but the ability to correct skew non-uniformity is limited

Engineering Contradiction:

Improvesupport structureVSAvoidskew non-uniformity correction

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent introduces a tiltable support structure that allows the overhead RF coil antenna assembly to be dynamically adjusted in angle relative to the workpiece. This dynamic positioning capability enables correction of skew non-uniformities by optimizing the angular orientation of the coils, thereby improving etch rate uniformity without increasing the number of coils or RF power sources.

Inventive Principle:

Principle #15Dynamics

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 solution enables the elimination of skew non-uniformities, allowing for the subsequent correction of remaining radial non-uniformities by adjusting RF power levels, resulting in a uniformly distributed etch rate across the wafer surface.

Implementation Method 1

inductively coupled RF plasma in which the plasma source consists of a coil antenna

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

Plural actuators fixed with respect to the shoulder ring are spaced about the shoulder ring at periodic intervals. Each one of the plural actuators has an axially movable arm and a motor driving the movable arm in an axial direction.

Methodology Applied

Scientific EffectMechanical actuation:

Data Source

PatentUS9330887B2Plasma reactor with tiltable overhead RF inductive source

Publication Date: 2016.05.03 APPLIED MATERIALS INC

AI summary

Correction of skew in plasma etch rate distribution is performed by tilting the overhead RF source power applicator about a tilt axis whose angle is determined from skew in processing data. Complete freedom of movement is provided by incorporating exactly three axial motion servos supporting a floating plate from which the overhead RF source power applicator is suspended.