Optical Wafer Edge Heating to Prevent Backside Deposition

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Solution Overview

Problem

Existing technologies face challenges in preventing unwanted backside deposition on wafers during condensation-based deposition processes, leading to adverse effects and requiring inefficient wet cleaning operations.

Innovation Solution

A substrate support system that includes an optical wafer edge heating unit with light sources and light emission surfaces, which radiatively heat the circumferential edge region of the wafer to a temperature where deposition rates approach zero, creating a temperature differential to prevent backside deposition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If condensation-based deposition is used to deposit film on wafer frontside, then deposition efficiency is improved, but backside deposition occurs causing contamination

Engineering Contradiction:

Improvedeposition efficiencyVSAvoidbackside deposition contamination

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by creating a temperature differential between different regions of the wafer. The edge region is heated to a higher temperature (e.g., 100-200°C) than the center region, establishing distinct thermal zones that prevent condensation at the edges while allowing it in the center, thus solving the backside deposition problem without affecting frontside deposition efficiency

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements preliminary anti-action by pre-heating the wafer edge region before the condensation-based deposition process begins. This preliminary heating creates a temperature gradient that actively prevents process gases from condensing on the backside edges, countering the harmful deposition effect before it can occur

Inventive Principle:

Principle #9Preliminary anti-action

2Object-affected harmful factors

If wet cleaning is used to remove backside deposition, then contamination is removed, but processing time increases and throughput decreases

Engineering Contradiction:

Improvebackside deposition removalVSAvoidprocessing time

Core Design Contradiction:

Object-affected harmful factorsVSLoss of time

Solution Approach 1:

The patent applies preliminary action by preventing backside deposition through edge heating during the deposition process itself. This proactive prevention eliminates the need for subsequent wet cleaning operations, thereby saving processing time and maintaining high throughput while still achieving complete contamination removal

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the harmful condensation effect into a beneficial prevention mechanism by using controlled heating at the wafer edges. The same condensation process that causes problems is countered by creating a thermal environment where condensation is thermodynamically unfavorable at the edges, thus preventing contamination without requiring additional cleaning steps

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Temperature

If light sources are positioned close to wafer edge for heating, then heating efficiency is improved, but risk of direct light exposure and overheating increases

Engineering Contradiction:

Improveedge region heating efficiencyVSAvoiddirect light exposure and overheating risk

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The patent uses an intermediary approach by positioning light sources at an offset distance from the wafer edge rather than directly adjacent to it. This offset positioning allows light to reach the target edge region through reflection or scattered paths, providing effective heating while reducing the risk of direct excessive light exposure and localized overheating

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent applies dimensionality change by considering the three-dimensional spatial relationship between light sources and the wafer surface. By positioning light sources at an offset distance and potentially at angles, the system achieves effective heating coverage through spatial distribution, reducing hot spots while maintaining heating efficiency

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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

The system effectively reduces or prevents unwanted backside deposition by maintaining the circumferential edge region at a temperature where deposition is negligible, thereby improving processing efficiency and reducing contamination risks.

Implementation Method 1

optical wafer edge heating unit having one or more light sources and one or more light emission surfaces, wherein the one or more light emission surfaces may encircle the outer boundary when viewed along the center axis, may be positioned radially outwards from the outer boundary when viewed along the center axis, may be positioned radially offset below the outer boundary by an offset distance when viewed along an axis perpendicular to the center axis, and may direct light in a direction having a directional component that is parallel to the center axis

Methodology Applied

Scientific EffectRadiative heating: Thermal Radiation

Data Source

PatentUS20250125165A1Apparatuses for radiative heating of an edge region of a semiconductor wafer

Publication Date: 2025.04.17 LAM RES CORP

AI summary

Provided herein are various apparatuses and systems for providing edge heating of semiconductor wafers using optical means. Such systems may direct radiant energy towards the edge region of a semiconductor wafer.