Thermal Plate Temperature Correction for Line Width Consistency

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Solution Overview

Problem

In photolithography processes, accurately controlling the temperature of thermal processing plates to achieve consistent line widths on wafers is challenging due to variations in thermal resistance across regions, leading to subjective and time-consuming try-and-error adjustments by operators.

Innovation Solution

A method to accurately estimate processing states of substrates after temperature setting changes by using a specific expression to calculate improvement components, allowing for precise temperature adjustments across regions without relying on operator expertise, using a Zernike polynomial to decompose in-plane tendencies and calculate optimal temperature correction values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If temperature correction values are set through try-and-error process by operator, then temperature adjustment can be made, but time consumption increases and consistency decreases

Engineering Contradiction:

Improveline width consistencyVSAvoidtemperature setting time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The system measures actual line widths after thermal processing and feeds this information back to automatically calculate optimal temperature correction values. This closed-loop feedback mechanism eliminates the need for manual try-and-error adjustments, reducing setting time while ensuring consistent line width precision through objective measurement and calculation.

Inventive Principle:

Principle #23Feedback

2Manufacturing precision

If manual temperature correction setting is performed, then operator judgment is used, but subjectivity leads to variations among operators

Engineering Contradiction:

Improveline width controlVSAvoidoperator dependency

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The system performs self-adjustment by automatically calculating temperature correction values based on measured line width data and thermal resistance characteristics. The apparatus eliminates operator dependency by making the system itself perform the correction value determination, ensuring consistent, objective results regardless of which operator is performing the setup.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent replaces manual operator judgment with an automated calculation system that uses measured line width data and thermal resistance models to determine correction values. This substitution of mechanical/manual processes with automated computational processes eliminates subjectivity and ensures reproducible results.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If multiple repeated adjustments are made to achieve optimal line width, then temperature precision can be improved, but productivity decreases

Engineering Contradiction:

Improveline width accuracyVSAvoidprocess efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The system performs preliminary measurement of line widths and calculates the optimal temperature correction values before actual production runs. By determining correction values in advance based on measured data and thermal models, the system avoids repeated adjustments during production, thereby maintaining high precision while improving overall process efficiency and productivity.

Inventive Principle:

Principle #10Preliminary 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 approach enables accurate and efficient temperature setting of thermal processing plates, reducing the need for repetitive adjustments and shortening the process time, ensuring consistent line widths regardless of operator skill levels.

Implementation Method 1

The thermal plate has a heater embedded therein which generates heat by power feeding

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

the heat generated by the heater adjusts the thermal plate to a predetermined temperature

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS7897897B2Temperature setting method of thermal processing plate, computer-readable recording medium recording program thereon, and temperature setting apparatus for thermal processing plate

Publication Date: 2011.03.01 TOKYO ELECTRON LTD

AI summary

In the present invention, a thermal plate of a PEB unit is divided into a plurality of thermal plate regions, and a temperature is settable for each of the thermal plate regions. A temperature correction value for adjusting the temperature within the thermal plate is settable for each of the thermal plate regions of the thermal plate. The line widths within the substrate which has been subjected to the photolithography process are measured, and an improvement in-plane tendency Za improved by change of the temperature settings is subtracted from an in-plane tendency Z of the measured line widths within the substrate to calculate an in-plane tendency Zb of the line widths within the substrate after change of temperature settings. The improvement in-plane tendency Za is calculated using the following expression.Za=−1×α×MT (α: a resist heat sensitivity, M: a calculation model, and T: temperature correction values for thermal plate regions).