Biased Precoat Electrostatic Chuck Cover for High-Density Plasma Defect Reduction

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Solution Overview

Problem

High-density plasma chemical vapor deposition processes face wafer defects due to dislodged material from the deposition chamber's interior surfaces, which embeds into the film and causes yield losses, requiring lengthy downtime for chamber part replacements.

Innovation Solution

A biased precoat process is implemented where a protective electrostatic chuck cover is biased with high-frequency RF power during the precoat step, replicating chamber conditions to dislodge loose material onto the cover instead of the wafer, minimizing defects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If bias is applied to the first silicon wafer after cleaning and conditioning, then film deposition can proceed, but gas flow patterns dislodge loose material from the chamber that embeds in the film causing defects

Engineering Contradiction:

Improvefilm deposition throughputVSAvoidwafer defect rate

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies bias to the protective cover during the precoat step before processing silicon wafers. This preliminary action dislodges loose material from the chamber surfaces onto the protective cover instead of onto subsequent wafers, preventing defect formation while maintaining production throughput

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The protective cover acts as an intermediary substrate that intercepts dislodged material. By placing the cover in position and applying bias to it during precoat, loose particles are captured on the cover rather than on valuable silicon wafers, serving as a sacrificial intermediary that protects the actual product

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the protective cover is not biased during precoat, then the cover remains intact, but loose material dislodges during subsequent wafer processing causing yield losses

Engineering Contradiction:

Improveprotective cover integrityVSAvoidwafer yield

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent performs the material dislodging action in advance during the precoat step by applying bias to the protective cover. This preliminary action removes loose material before wafer processing begins, ensuring both cover integrity and high wafer yield without requiring cover replacement

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If dome and injectors are replaced to eliminate loose material, then wafer defects are reduced, but twelve to sixteen hours of unscheduled downtime occurs

Engineering Contradiction:

Improvewafer defect rateVSAvoidtool downtime

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent enables the deposition chamber to self-clean by using the bias-induced gas flow patterns during normal precoat operation to dislodge and remove loose material. This self-service mechanism eliminates the need for manual part replacement and extends tool operation without unscheduled downtime

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent maintains continuous productive operation by performing material removal during the regular precoat step rather than requiring separate maintenance downtime. The useful action of precoat serves dual purposes: conditioning the chamber and removing loose material, ensuring uninterrupted production

Inventive Principle:

Principle #20Continuity of useful action

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 method significantly reduces first wafer defects by over 75% by ensuring loose particles fall on the protective cover during precoat, preventing embedding in the film and subsequent chemical-mechanical polishing issues, thereby reducing yield losses and avoiding extensive downtime.

Implementation Method 1

application of high frequency (HF) radio frequency (RF) power to bias a protective electrostatic chuck cover (PEC) wafer via an electrostatic chuck during precoat

Methodology Applied

Scientific EffectRadio frequency power heating: Dielectric Heating

Implementation Method 2

The application of 500 watts or more of HF RF power that biases the PEC wafer causes gas flow patterns in the deposition chamber that dislodge loose material and particles

Methodology Applied

Scientific EffectGas flow convection: Convection

Implementation Method 3

applying power to bias the protective cover while simultaneously precoating the deposition chamber with an oxide

Methodology Applied

Scientific EffectElectrostatic attraction: Electrostatics

Data Source

PatentUS7964517B2Use of a biased precoat for reduced first wafer defects in high-density plasma process

Publication Date: 2011.06.21 TEXAS INSTRUMENTS INC

AI summary

According to various embodiments, the present teachings include methods for reducing first wafer defects in a high-density plasma chemical vapor deposition process. In an exemplary embodiment, the method can include running a deposition chamber for deposition of film on a first batch of silicon wafers and then cleaning interior surfaces of the deposition chamber. The method can further include inserting a protective electrostatic chuck cover (PEC) wafer on an electrostatic chuck in the deposition chamber and applying power to bias the PEC wafer while simultaneously precoating the deposition chamber with an oxide. The exemplary method can also include re-starting the deposition chamber for deposition of film on a second batch of silicon wafers.