Semiconductor Dopant Activation via Dual-Lamp Heat Treatment
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Solution Overview
Problem
Current methods for impurity introduction in semiconductor manufacturing, such as ion injection and mono-molecular layer doping, face challenges in accurately introducing impurities into extremely shallow surface layers of semiconductor wafers, leading to increased costs and space requirements due to the need for multiple heat treatment devices and prolonged treatment times.
Innovation Solution
A heat treatment method and device that utilize a single chamber for both preliminary heat treatment and flash light activation, where a substrate with a mono- or multi-molecular layer of dopants is heated through a combination of halogen lamps for preliminary treatment and flash lamps for activation, allowing for precise introduction and activation of impurities in a shallow surface layer without excessive diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If ion injection technique is used for impurity introduction, then injection depth and concentration can be controlled, but it generates crystal defects and cannot accurately inject impurities into extremely shallow surface layer region
Solution Approach 1:
The patent replaces the mechanical ion injection process with a chemical wet treatment process to form a mono-molecular layer of impurities on the substrate surface. This substitution eliminates the crystal defects caused by high-energy ion collision while achieving precise shallow-depth impurity introduction through controlled chemical deposition followed by heat treatment.
2Reliability
If separate RTA and FLA heat treatment devices are used for impurity diffusion and activation, then treatment processes can be performed sequentially, but it increases device preparation cost, installation space, and treatment time
Solution Approach 1:
The patent combines the RTA and FLA heat treatment functions into a single heat treatment device. The device includes both a diffuse light irradiation unit (for RTA-like treatment) and a flash light irradiation unit (for FLA-like treatment), allowing sequential performance of both treatment processes in one device, thereby reducing device count, installation space, and treatment time while maintaining process effectiveness.
3Productivity
If flash light irradiation is used for rapid heating, then treatment time is reduced, but it may cause abnormal diffusion of impurities if temperature control is not precise
Solution Approach 1:
The patent applies preliminary diffuse light irradiation heating before flash light irradiation. This preliminary heating step prepares the substrate and impurity layer by achieving a controlled initial temperature rise in a gentle manner, ensuring that when the intense flash light irradiation occurs, the impurities are already in a state that prevents abnormal diffusion while still enabling rapid activation. This sequential approach ensures precise temperature control throughout the rapid heating process.
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 reduces the need for multiple heat treatment devices, minimizes treatment time, and prevents abnormal diffusion of impurities, enabling efficient and precise introduction of dopants into the semiconductor wafer's surface layer while simplifying device installation and reducing costs.
Implementation Method 1
through irradiation with light from a first lamp, with preliminary heat treatment in a first temperature band
Implementation Method 2
by heating the substrate provided with the preliminary heat treatment in the step (c) and placed in the chamber from the first temperature band to a second temperature band higher than the first temperature band through irradiation with flash light from a second lamp
Implementation Method 3
the impurities are diffused into the outermost surface layer of the substrate through heat treatment thereafter to introduce the impurities only into an extremely shallow region
Data Source
AI summary
First, a substrate with one main surface on which a thin film of at least one of a mono-molecular layer and a multi-molecular layer including dopants is formed is prepared. Subsequently, the prepared substrate is placed in a chamber, and dopants included in the thin film are introduced from the thin film into a surface layer of the substrate by providing the substrate, through irradiation with light from a first lamp, with preliminary heat treatment in a first temperature band higher than a temperature before heating. Then, the dopants introduced into the surface layer of the substrate are activated by heating the substrate provided with the preliminary heat treatment and placed in the chamber from the first temperature band to a second temperature band higher than the first temperature band through irradiation with flash light from a second lamp.