Wafer Bow Correction via Localized Thermal Stress Tuning

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Solution Overview

Problem

Semiconductor fabrication processes, particularly photolithography, require a flat or planar wafer surface to ensure accurate pattern projection, but internal stresses from material deposition and processing steps can cause wafer bowing, leading to overlay errors and precision issues in lithography.

Innovation Solution

A wafer processing device with a first hot plate for uniform heating and a second hot plate with multiple independently controllable heating zones is used to apply a targeted heat signature to the wafer, modifying internal stresses in a stressor film on the wafer's backside surface to correct or modify wafer bow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If uniform heating is applied across the entire wafer surface, then the wafer temperature is stabilized for processing, but wafer bow caused by internal stresses cannot be corrected

Engineering Contradiction:

Improvewafer temperature stabilityVSAvoidwafer flatness

Core Design Contradiction:

Stability of the object's compositionVSShape

Solution Approach 1:

The heating system is divided into multiple independently controllable heating zones across the wafer surface. Each zone can be controlled to provide different temperature profiles, allowing localized stress treatment to correct wafer bow while maintaining overall temperature stability for processing.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the wafer are subjected to different temperature conditions. Specifically, certain heating zones are targeted to apply localized thermal stress to correct bow in those areas, while other zones maintain uniform temperatures suitable for processing requirements.

Inventive Principle:

Principle #3Local quality

2Manufacturing precision

If localized heating zones are used to correct wafer bow, then wafer shape precision is improved, but device complexity increases

Engineering Contradiction:

Improvewafer flatness controlVSAvoidheating system complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The heating system is segmented into multiple independently controllable zones, each capable of being adjusted to provide specific temperature profiles for correcting localized wafer bow while maintaining overall system manageability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system controls wafer bow by adjusting temperature parameters in different heating zones. By varying the temperature in each zone independently, the system can correct different types and magnitudes of bow without requiring complex mechanical or structural modifications.

Inventive Principle:

Principle #35Parameter changes

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 allows for precise correction of wafer bow, achieving an average z-height deviation of less than 10 microns, thereby enhancing lithography precision and reducing overlay errors.

Implementation Method 1

The first hot plate can be configured to heat a wafer. For example, the first hot plate can provide uniform heating across a surface of the first hot plate.

Methodology Applied

Scientific EffectUniform heating: Conduction (thermal)

Implementation Method 2

The second hot plate has multiple heating zones with each heating zone independently controllable such that each heating zone can be set to a temperature value independent of other heating zones

Methodology Applied

Scientific EffectLocalized stress treatment using heat zones: Thermal Expansion

Implementation Method 3

modify internal stresses in a stressor film on the wafer's backside surface to correct or modify wafer bow

Methodology Applied

Scientific EffectThermal stress modification: Heat Treatment

Implementation Method 4

The controller can be configured to control the first hot plate to provide the uniform heating, receive a bow measurement from wafer curvature measurement of a wafer

Methodology Applied

Scientific EffectWafer curvature measurement:

Data Source

PatentUS12204253B2In-situ lithography pattern enhancement with localized stress treatment tuning using heat zones

Publication Date: 2025.01.21 TOKYO ELECTRON LTD

AI summary

Aspects of the present disclosure provide a wafer processing device for optimizing wafer shape. For example, the wafer processing device can include a first hot plate, a second hot plate and a controller. The first hot plate can be configured to heat a wafer. For example, the first hot plate can provide uniform heating across a surface of the first hot plate. The second hot plate has multiple heating zones with each heating zone independently controllable such that each heating zone can be set to a temperature value independent of other heating zones. The controller is configured to control the first hot plate to provide the uniform heating, receive a bow measurement from wafer curvature measurement of a wafer, and set the multiple heating zones of the second hot plate to their respective temperature values that correspond to the bow measurement.