Sputtering Apparatus with Segmented Magnetic Field for Catalyst Deposition
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Solution Overview
Problem
Existing sputtering apparatuses face challenges in efficiently and uniformly depositing an extremely low concentration of metal catalyst on amorphous silicon while preventing magnetization and maintaining a short pre-sputtering time, which can lead to unstable crystallization of amorphous silicon for thin-film transistor applications.
Innovation Solution
A sputtering apparatus with a magnetic assembly only in the pre-sputtering region, separating the process chamber into distinct regions for pre-sputtering and deposition, using a metal target and substrate holder with controlled electrodes and shields to manage plasma and catalyst deposition, ensuring no magnetization during deposition and efficient, uniform catalyst distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a magnetic assembly is used in the deposition region to enhance sputtering efficiency, then deposition speed is improved, but the metal catalyst becomes magnetized during deposition
Solution Approach 1:
The process chamber is divided into two distinct regions: a pre-sputtering region (first region) where the magnetic assembly is located, and a deposition region (second region) where deposition occurs without magnetic field interference. The target is moved between these regions to perform pre-sputtering in the magnetic field and then deposition in the non-magnetic field, thereby achieving high deposition speed without catalyst magnetization.
Solution Approach 2:
The magnetic assembly is extracted from the deposition region and placed only in the pre-sputtering region. This separation ensures that the magnetic field is applied only during pre-sputtering to enhance cleaning efficiency, while being completely removed from the deposition process to prevent catalyst magnetization, thus resolving the contradiction between cleaning efficiency and catalyst purity.
2Reliability
If pre-sputtering time is extended to ensure thorough cleaning of the target, then target cleanliness is improved, but overall process time increases
Solution Approach 1:
The target is periodically moved between the pre-sputtering region and deposition region. During pre-sputtering, the target is positioned in the first region with the magnetic assembly for intensive cleaning. Then it is quickly moved to the second region for deposition. This periodic movement allows thorough cleaning in a concentrated time period without extending the overall process time, as the magnetic field is only active during pre-sputtering.
Solution Approach 2:
The magnetic field strength and plasma power are optimized during pre-sputtering to achieve maximum cleaning efficiency in minimal time. By adjusting these parameters, the pre-sputtering process is accelerated while maintaining thorough target cleaning, thus reducing the time penalty associated with extended pre-sputtering.
3Quantity of substance
If metal catalyst is deposited at extremely low concentration to achieve desired properties, then material usage is optimized, but uniformity and stability of deposition become difficult to control
Solution Approach 1:
The target surface is preliminarily cleaned and activated in the pre-sputtering region before deposition. This preliminary action ensures that the target surface is free from contaminants and has uniform properties, which provides a consistent foundation for subsequent low-concentration catalyst deposition. As a result, even at extremely low concentrations, the catalyst deposits uniformly and stably across the substrate.
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
Enables a short and stable pre-sputtering process, preventing magnetization of the metal catalyst during deposition, and achieving uniform, low-concentration metal catalyst deposition on amorphous silicon, thereby improving the crystallization efficiency and stability of the resulting poly-Si layer for thin-film transistors.
Implementation Method 1
a magnetic assembly in the first region of the process chamber, the magnetic assembly being interposed between the target transfer unit and a wall of the process chamber
Implementation Method 2
the crystallization-inducing metal may be deposited via sputtering on a substrate from a metal target made of the crystallization-inducing metal using plasma
Implementation Method 3
a first electrode inside the target transfer unit, and a second electrode inside the substrate holder, the second electrode receiving a power voltage having a polarity different from that of the first electrode
Data Source
AI summary
A sputtering apparatus includes a process chamber having first and second regions, a metal target inside the process chamber, a target transfer unit inside the process chamber, the target transfer unit being configured to move the metal target between the first and second regions, a substrate holder in the second region of the process chamber, and a magnetic assembly in the first region of the process chamber, the magnetic assembly being interposed between the target transfer unit and a wall of the process chamber.