Semiconductor Wafer Flash Heating With Staged Temperature Ramps

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Solution Overview

Problem

Existing flash lamp annealing methods face challenges in achieving high activation of impurities while minimizing thermal history, especially for new materials like germanium and 3-D semiconductor devices, where excessive thermal effects can deteriorate device properties.

Innovation Solution

A method involving two-stage light irradiation, where a substrate is first preheated using continuous halogen lamps to a lower temperature, followed by flash lamp irradiation in multiple stages to rapidly increase the surface temperature to a treatment temperature, thereby reducing the overall heat input and thermal history.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If flash lamp annealing is used to activate impurities, then activation efficiency is improved, but thermal history increases causing deep diffusion of impurities

Engineering Contradiction:

Improveactivation efficiencyVSAvoidthermal history

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The heating process is segmented into multiple stages: preheating stage using halogen lamps to reach a base temperature, followed by multiple flash lamp irradiation stages (first flash, second flash) to progressively reach the target temperature. This segmentation allows controlled temperature increase while minimizing excessive thermal diffusion.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The substrate is preheated to a predetermined temperature using halogen lamps before flash lamp irradiation is applied. This preliminary action reduces the temperature differential required during flash heating, thereby reducing the thermal history and preventing excessive diffusion of impurities.

Inventive Principle:

Principle #10Preliminary action

2Temperature

If preheating is performed using halogen lamps, then the substrate reaches a stable base temperature, but the heating time becomes excessively long

Engineering Contradiction:

Improvebase temperature stabilityVSAvoidpreheating time

Core Design Contradiction:

TemperatureVSLoss of time

Solution Approach 1:

The heating process uses periodic flash lamp irradiation interspersed with intervals, rather than continuous heating. The flash lamps provide intense periodic heating bursts that efficiently raise the temperature from the preheated base state to the target temperature, significantly reducing total heating time compared to continuous halogen lamp heating.

Inventive Principle:

Principle #19Periodic action

3Loss of time

If flash lamp irradiation is applied directly without preheating, then heating time is reduced, but the surface temperature cannot reach the target temperature

Engineering Contradiction:

Improveheating timeVSAvoidsurface temperature achievement

Core Design Contradiction:

Loss of timeVSTemperature

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

4Manufacturing precision

If flash lamp annealing is used for new materials like germanium, then high carrier mobility is achieved, but excessive thermal effects cause material degradation

Engineering Contradiction:

Improvecarrier mobilityVSAvoidthermal effects on material

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Inventive Principle:

Principle #10Preliminary action

5Manufacturing precision

If flash lamp annealing is used for 3-D devices, then activation of upper layer is improved, but thermal effects deteriorate lower layer properties

Engineering Contradiction:

Improveactivation of upper layerVSAvoidthermal effects on lower layer

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

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 effectively reduces the amount of heat given to the substrate, allowing for higher activation of impurities with reduced diffusion, while preventing excessive thermal effects on existing layers in 3-D devices.

Implementation Method 1

irradiating the substrate with light from a continuous lighting lamp to heat the substrate

Methodology Applied

Scientific EffectLight irradiation heating: Absorption (EM radiation)

Implementation Method 2

irradiating a front surface of the substrate with a flash of light from a flash lamp to increase the temperature of the front surface in multiple stages

Methodology Applied

Scientific EffectLight irradiation heating: Absorption (EM radiation)

Data Source

PatentUS20250054772A1Heat treatment method for heating substrate by light irradiation

Publication Date: 2025.02.13 SCREEN HOLDINGS CO LTD

AI summary

A semiconductor wafer is preheated to a predetermined preheating temperature. Thereafter, flash heating for heating a front surface of the semiconductor wafer is performed by irradiating the front surface with flashes of light. The flash heating includes a first flash heating process in which the temperature of the front surface of the semiconductor wafer is increased at a first temperature increase rate, and a second flash heating process in which the temperature of the front surface of the semiconductor wafer is increased at a second temperature increase rate higher than the first temperature increase rate. The preheating temperature is made lower than a reaction temperature, and a shortage of the preheating is compensated for by the first flash heating process. Finally, the second flash heating process increases the temperature of the front surface of the semiconductor wafer to a target treatment temperature.