Flash Lamp Array Zone Control for Wafer Temperature Uniformity
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Solution Overview
Problem
Existing heat treatment methods for semiconductor wafers result in uneven temperature distributions during flash lamp annealing, leading to variations in impurity activation and sheet resistance due to temperature drops in the peripheral regions compared to the central regions.
Innovation Solution
A heat treatment method and apparatus that utilize a plurality of flash lamps arranged in a plane, with the irradiation time for the peripheral zone being longer than the central zone, and simultaneously applying flash light to both regions to maintain uniform temperature distribution and prevent temperature drops, ensuring consistent impurity activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If preheating with halogen lamps is performed to raise wafer temperature quickly, then processing time is reduced, but uneven temperature distribution occurs between peripheral and central portions
Solution Approach 1:
The flash lamp array is divided into multiple independent zones (central zone and peripheral zones) that can be controlled separately. Each zone's flash lamp irradiation time is independently adjusted, allowing local compensation for temperature differences. The peripheral zones receive longer irradiation times to compensate for heat loss, while the central zone receives shorter irradiation times to prevent overheating.
2Reliability
If flash light irradiation time is extended to activate impurities, then impurity activation is improved, but deep diffusion of impurities occurs
Solution Approach 1:
The invention uses pulsed flash light irradiation instead of continuous heating. The flash lamps emit light in extremely short pulses (microseconds to milliseconds), providing intense thermal energy that rapidly activates impurities. The periodic pulsed action allows the wafer surface to reach activation temperature quickly and then cool rapidly, preventing deep diffusion while ensuring complete impurity activation.
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
The method achieves uniform temperature distribution across the semiconductor wafer, ensuring consistent impurity activation and preventing relative temperature drops in peripheral regions, thereby improving the quality of semiconductor device formation.
Implementation Method 1
irradiating a substrate with flash light from a plurality of flash lamps arrayed in a plane to heat the substrate
Implementation Method 2
The xenon flash lamps have a spectral distribution of radiation ranging from ultraviolet to near-infrared regions
Implementation Method 3
irradiating a substrate with light from a halogen lamp to perform preheating
Data Source
AI summary
A plurality of flash lamps that irradiate a semiconductor wafer with flash light are arrayed in a plane. The array of the plurality of flash lamps is divided into two zones: a central zone including a region opposed to a central portion of the semiconductor wafer to be treated, and a peripheral zone outside the central zone. During flash light irradiation, an emission time of a flash lamp belonging to the peripheral zone is set to be longer than an emission time of a flash lamp belonging to the central zone. Thus, a greater amount of flash light is applied to the peripheral portion of the semiconductor wafer, where a temperature drop is relatively likely to occur, than to the central portion thereof, thus preventing a relative temperature drop in the peripheral portion of the semiconductor wafer during flash heating.