Flash Lamp Annealing Oxygen Removal via Low-Temp Preheating

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Solution Overview

Problem

Flash heating treatment of semiconductor wafers with high dielectric constant thin films fails to achieve high dielectric constants due to increased silicon oxide film thickness caused by oxygen absorption, particularly moisture-derived oxygen.

Innovation Solution

A heat treatment method involving preheating the substrate at 100-200°C to desorb moisture, followed by further preheating and flash lamp annealing in a controlled atmosphere with reduced oxygen levels, using a heat treatment apparatus with a chamber, preheater, flash lamp, and controlled gas management to minimize oxygen exposure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If flash heating treatment is performed on semiconductor wafer with high dielectric constant thin film, then annealing of deposited film is achieved, but silicon oxide film thickness increases due to oxygen absorption

Engineering Contradiction:

Improveannealing temperatureVSAvoidsilicon oxide film thickness

Core Design Contradiction:

TemperatureVSLength of stationary object

Solution Approach 1:

The patent applies preliminary action by performing a first preheating treatment at 100-200°C before the main flash heating treatment. This preliminary step desorbs moisture and removes oxygen from the silicon oxide film, preventing oxygen-induced thickness increase during subsequent high-temperature annealing while enabling proper annealing of the high dielectric constant thin film

Inventive Principle:

Principle #10Preliminary action

2Stability of the object's composition

If heating treatment is performed to anneal high dielectric constant thin film, then film crystallinity is improved, but leakage current increases due to silicon oxide film thickening

Engineering Contradiction:

Improvefilm crystallinityVSAvoidleakage current

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The patent removes oxygen through preliminary heating at 100-200°C before main annealing, preventing oxygen diffusion into the silicon oxide film during high-temperature treatment. This maintains film thickness stability and prevents leakage current increase while still achieving proper annealing and improved crystallinity of the high dielectric constant thin film

Inventive Principle:

Principle #10Preliminary action

3Productivity

If flash lamp annealing is applied to semiconductor wafer with new stack structure, then processing speed is maintained, but oxygen absorption occurs during treatment

Engineering Contradiction:

Improveprocessing speedVSAvoidoxygen absorption

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent performs preliminary heating at 100-200°C to remove oxygen and moisture before the main flash lamp annealing process. This preliminary oxygen removal prevents oxygen absorption during the rapid high-temperature treatment, maintaining both processing speed and preventing harmful oxygen effects on the silicon oxide film

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 method effectively desorbs moisture and reduces oxygen-derived thickness increases, allowing for flash heating with minimal oxygen impact, thereby maintaining the high dielectric constant of the thin film.

Implementation Method 1

heating the substrate at a first preheating temperature ranging from 100 to 200° C. enables, for example, the moisture absorbed on the surface of the substrate in trace amounts to be desorbed from the surface

Methodology Applied

Scientific EffectDesorption: Desorption

Implementation Method 2

heating the substrate in the chamber at a first preheating temperature ranging from 100 to 200° C.

Methodology Applied

Scientific EffectThermal heating: Heating

Implementation Method 3

emitting the flashlight from a flash lamp to a front surface of the substrate

Methodology Applied

Scientific EffectFlash lamp heating: Heating

Implementation Method 4

The spectral power distribution of the xenon flash lamp ranges from the ultraviolet region to the near-infrared region. The light produced by the xenon flash lamp has a wavelength shorter than that of a conventional halogen lamp, and has a fundamental absorption band almost identical to that of a semiconductor wafer made of silicon.

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS11574824B2Heat treatment method including low temperature degassing before flash lamp anneal and heat treatment apparatus thereof

Publication Date: 2023.02.07 SCREEN HOLDINGS CO LTD

AI summary

A semiconductor wafer to be treated is heated at a first preheating temperature ranging from 100 to 200° C. while a pressure in a chamber housing the semiconductor wafer is reduced to a pressure lower than an atmospheric pressure. After the semiconductor wafer is preheated to increase the temperature into a second preheating temperature ranging from 500 to 700° C. while the pressure in the chamber is restored to a pressure higher than the reduced pressure, a flash lamp emits a flashlight to a surface of the semiconductor wafer. Heating the semiconductor wafer at the first preheating temperature that is a relatively low temperature enables, for example, the moisture absorbed on the surface of the semiconductor wafer in trace amounts to be desorbed from the surface, and also enables the flash heating treatment to be performed with oxygen derived from such absorption removed as much as possible.