Rapid Thermal Processing Lamp Control for Semiconductor Substrate Temperature

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Solution Overview

Problem

Conventional rapid thermal processing apparatuses face challenges in accurately controlling the temperature of semiconductor substrates with varying reflectivity, leading to temperature gradients and inaccurate temperature measurements, especially when the light shading characteristic is inadequate.

Innovation Solution

The apparatus includes a processing chamber with a substrate support part and heating lamps, where the irradiation intensity of the lamps is controlled based on pre-measured reflectivity to maintain equal substrate and support part temperatures, and uses intermittent lamp operation to separate emission light from radiation light for precise temperature measurement.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If continuous lamp irradiation is used for heating, then heating efficiency is improved, but temperature measurement accuracy deteriorates due to light interference

Engineering Contradiction:

Improveheating efficiencyVSAvoidtemperature measurement accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The heating lamps operate in periodic cycles, alternating between irradiation (heating) and non-irradiation (measurement) states. This periodic action allows the system to achieve both efficient heating during irradiation phases and accurate temperature measurement during non-irradiation phases, resolving the contradiction between heating efficiency and measurement accuracy.

Inventive Principle:

Principle #19Periodic action

2Speed

If lamp irradiation intensity is increased for faster heating, then processing speed is improved, but temperature control accuracy deteriorates

Engineering Contradiction:

Improveprocessing speedVSAvoidtemperature control accuracy

Core Design Contradiction:

SpeedVSManufacturing precision

Solution Approach 1:

The system employs feedback control where the radiation light sensor continuously monitors substrate temperature and feeds this information back to the control unit. The control unit adjusts the lamp irradiation intensity based on the measured temperature, enabling both rapid heating and precise temperature control. The feedback mechanism ensures that high irradiation intensity can be applied for fast heating while maintaining accurate temperature control through real-time adjustments.

Inventive Principle:

Principle #23Feedback

3Power

If high irradiation intensity is applied to achieve rapid heating, then heating speed is improved, but temperature measurement accuracy deteriorates due to insufficient light shading

Engineering Contradiction:

Improveheating powerVSAvoidtemperature measurement accuracy

Core Design Contradiction:

PowerVSMeasurement precision

Solution Approach 1:

By implementing periodic irradiation cycles with sufficient measurement intervals, the system allows high irradiation intensity to be applied for rapid heating while ensuring that temperature measurements are taken during non-irradiation periods when light interference is eliminated. This temporal separation resolves the contradiction between high heating power and measurement accuracy.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The control unit acts as an intermediary that coordinates between the heating lamps and radiation light sensor. It ensures that measurement operations are performed during non-irradiation periods, effectively mediating the conflict between high-power heating and accurate measurement by timing their operations appropriately.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 ensures consistent maximum temperature, minimizes temperature gradients, and allows for accurate temperature control across semiconductor substrates with different reflectivities, even at low substrate temperatures, by correcting lamp power based on reflectivity and using intermittent heating to isolate radiation light for precise measurement.

Implementation Method 1

a lamp part optically irradiating a substrate (1) supported by the substrate support part (3) and heating the substrate (1)

Methodology Applied

Scientific EffectOptical heating: Absorption (EM radiation)

Implementation Method 2

a radiation light sensor which is arranged on the back surface side of the substrate and receives the radiation light from the substrate back surface

Methodology Applied

Scientific EffectThermal radiation detection: Thermal Radiation

Data Source

PatentUS7844171B2Rapid thermal processing apparatus and method of manufacture of semiconductor device

Publication Date: 2010.11.30 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A rapid thermal processing apparatus comprises a processing chamber which subjects a semiconductor substrate to rapid thermal processing. A substrate support part is arranged in the processing chamber and supports the substrate. A lamp part optically irradiates the substrate supported by the substrate support part and heats the substrate. A thermo sensor is provided to measure a temperature of the substrate. A temperature computing part computes the temperature of the substrate based on an output signal of the thermo sensor. A control part controls an irradiation intensity of the lamp part according to the temperature computed by the temperature computing part. In this apparatus, the control part is provided to correct a control parameter of the irradiation intensity of the lamp part based on a measured reflectivity of a surface of the substrate.