Sputtering Film Formation with Impedance Control
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Solution Overview
Problem
Conventional sputtering methods for forming group III nitride semiconductor thin films struggle to achieve high crystalline quality and consistent +c polarity, leading to poor light emitting characteristics due to defects like anti-phase domain boundaries.
Innovation Solution
A film formation method using a vacuum processing apparatus with an impedance adjuster to control the substrate's electrical impedance, ensuring the epitaxial film is grown with +c polarity and reduced tilt and twist mosaic spreads, thereby improving the quality and reproducibility of the semiconductor thin films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If sputtering method is used to form group III nitride semiconductor thin film, then production cost is reduced and particle generation probability is low, but crystalline quality becomes poorer with greater mosaic spread
Solution Approach 1:
The patent applies parameter changes by optimizing sputtering conditions including using a dual-frequency RF power supply (13.56 MHz and 27.12 MHz), controlling substrate temperature between 500-1000°C, maintaining specific pressure ranges, and adjusting gas flow rates to achieve high-quality GaN films with low mosaic spread through precise parameter control
Solution Approach 2:
The patent implements preliminary action by performing plasma treatment on the substrate surface before sputtering deposition, and by using a buffer layer structure to prepare the substrate in advance, which improves nucleation and reduces mosaic spread in the subsequent film growth process
2Manufacturing precision
If MOCVD method is used to form group III nitride semiconductor thin film, then high-quality epitaxial film can be obtained with high productivity, but production cost increases and particle generation occurs
Solution Approach 1:
The patent substitutes the chemical vapor deposition mechanism (MOCVD) with a physical sputtering process, replacing chemical reactions with physical bombardment by ions and atoms, thereby achieving comparable film quality through a different physical mechanism that avoids the drawbacks of MOCVD
3Device complexity
If sputtering method is used without impedance control, then process is simpler, but consistent +c polarity cannot be achieved leading to defects like anti-phase domain boundaries
Solution Approach 1:
The patent implements feedback control by monitoring the electrical impedance of the substrate during sputtering and adjusting process parameters in real-time to maintain optimal conditions for consistent +c polarity formation, preventing anti-phase domain boundary defects through active control
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 epitaxial films with +c polarity and wurtzite structure, reducing defects and enhancing the quality and reproducibility of semiconductor light emitting elements and electronic elements.
Implementation Method 1
a sputtering method by using a vacuum processing apparatus including: a vacuum chamber capable of being vacuumed; a substrate holding portion which supports the substrate in the vacuum chamber; a heater capable of heating the substrate held by the substrate holding portion to a given temperature; a target electrode which is provided in the vacuum chamber and to which a target is attachable; a radio-frequency power supply which inputs radio-frequency power into the target via the target electrode
Data Source
AI summary
The present invention provides a film formation method and a film formation apparatus which can fabricate an epitaxial film with +c polarity by a sputtering method. In one embodiment of the present invention, the film formation method of epitaxially growing a semiconductor thin film with a wurtzite structure by the sputtering method on an epitaxial growth substrate heated to a predetermined temperature by a heater includes the following steps. First, the substrate is disposed on a substrate holding portion including the heater to be located at a predetermined distance away from the heater. Then, the epitaxial film of the semiconductor film with the wurtzite structure is formed on the substrate with the impedance of the substrate holding portion being adjusted.