Wafer Clamp Assembly Finger Segmentation for Deposition

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Solution Overview

Problem

Conventional wafer clamp rings cause significant edge exclusion and overheating during deposition processes, leading to reduced electrical die production and a risk of sticking due to large contact surfaces and heat flux.

Innovation Solution

A wafer clamp assembly with an outer annular member and radially extending finger members that contact the wafer at specific, hemispherical points, minimizing edge exclusion and heat transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a clamp ring with large contact surface is used to hold the wafer firmly, then the wafer is securely clamped to the support surface, but the edge exclusion area increases significantly reducing the usable wafer surface

Engineering Contradiction:

Improvewafer clamping stabilityVSAvoidusable wafer surface area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The clamp ring is segmented into multiple discrete contact points (fingers) rather than maintaining continuous contact. The wafer clamp assembly includes a clamp ring with multiple fingers extending inward, each finger having a contact surface that touches the wafer at separate locations. This segmentation reduces the total contact area while maintaining secure clamping through distributed contact points.

Inventive Principle:

Principle #1Segmentation

2Reliability

If a clamp ring with large contact surface is used to hold the wafer firmly, then the wafer is securely clamped to the support surface, but the heat flux from the clamp to the wafer increases causing overheating

Engineering Contradiction:

Improvewafer clamping stabilityVSAvoidwafer temperature at contact areas

Core Design Contradiction:

ReliabilityVSTemperature

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

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 reduces edge exclusion, minimizes heat flux, and decreases the risk of sticking, thereby increasing the usable wafer surface area for producing good electrical dies.

Implementation Method 1

the clamp ring is heated during the sputtering process due to ion bombardment from the plasma and a heat flux from the wafer clamp to the wafer takes place which makes the outer parts of the wafer overheated

Methodology Applied

Scientific EffectHeat flux: Conduction (thermal)

Implementation Method 2

the clamp ring is heated during the sputtering process due to ion bombardment from the plasma

Methodology Applied

Scientific EffectIon bombardment: Ion Beam

Implementation Method 3

During a sputter deposition process, for example, the wafer is held to a pedestal of a heater unit which is located in a chamber filled with a noble gas or reactive gas

Methodology Applied

Scientific EffectSputter deposition: Sputtering

Data Source

PatentUS8795479B2Wafer clamp assembly for holding a wafer during a deposition process

Publication Date: 2014.08.05 TEXAS INSTRUMENTS INC

AI summary

A wafer clamp assembly for holding a wafer during a deposition process comprises an outer annular member defining a central recess that has a diameter slightly greater than the diameter of the wafer. A plurality of finger members are carried by the outer annular member and extend radially inwardly from the outer annular member into the central recess, wherein each of the finger members has a free end for contacting the wafer during the deposition process.