Segmented Fin Buffer Layer for Quantum Well Device Punch-Through Control
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Solution Overview
Problem
Current semiconductor manufacturing techniques for high electron mobility transistors (HEMTs) face challenges in achieving high mobility and reliable operation, particularly in controlling the two-dimensional electron gas (2-DEG) surface charge density and punch-through voltages.
Innovation Solution
A method for forming a quantum well device involving a patterned substrate with a fin-like buffer layer, successive deposition of quantum well, barrier, cover, and dielectric layers, followed by metal gate formation and sidewall spacers, and etching to create recessed source and drain regions, utilizing specific etching gases and solutions like BCl3, KOH, and NaOH to achieve a structure with high mobility and improved punch-through voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional HEMT manufacturing techniques are used, then device structure is formed, but mobility is insufficient and punch-through voltages are not reliably controlled
Solution Approach 1:
The buffer layer is divided into multiple segments with different thicknesses (first buffer layer region with greater thickness, second buffer layer region with lesser thickness) separated by etched portions. This segmentation allows different regions to provide different functions: thicker regions maintain high 2-DEG density while thinner regions enable effective gate control and higher punch-through voltages, resolving the contradiction between reliability and manufacturing precision.
Solution Approach 2:
Different regions of the buffer layer are given different local properties through selective etching. The first buffer layer region retains greater thickness for high electron density, while the second buffer layer region has reduced thickness for improved gate control. This local differentiation allows the device to simultaneously achieve high reliability through maintained electron density and precise manufacturing control through localized thickness variation.
2Reliability
If buffer layer thickness is increased to maintain 2-DEG density, then reliability improves, but gate control capability deteriorates
Solution Approach 1:
The buffer layer is segmented into first and second regions with different thicknesses. The first region maintains greater thickness to preserve 2-DEG surface charge density and reliability, while the second region has reduced thickness to enable effective gate control and achieve desired punch-through voltages, thus resolving the contradiction between reliability and ease of operation.
Solution Approach 2:
The solution transitions from a uniform one-dimensional buffer layer to a spatially varying structure with thickness changes in the vertical dimension. By creating regions of different thicknesses within the buffer layer, the invention enables simultaneous optimization of electron density (requiring thicker regions) and gate control (requiring thinner regions), effectively resolving the contradiction through dimensional variation.
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 results in a quantum well device with enhanced mobility and reliability, offering better performance and higher punch-through voltages compared to prior art.
Implementation Method 1
perform etching process to the said buffer layer to form a fin-like structure
Implementation Method 2
successively deposit the quantum well layer, the barrier layer, the cover layer and the dielectric layer on the said buffer layer and surface of the fin-like structure
Data Source
AI summary
Embodiments provide a quantum well device and the method for forming this device with high mobility and higher punch through voltages. For forming the quantum well device, a buffer layer can be formed on a patterned substrate of a quantum well device. A fin-like structure can be formed through an etching process performed to the buffer layer. A quantum well layer, a barrier layer, a cover layer and a dielectric layer can be successively deposited on the buffer layer and surface of the fin-like structure. A metal layer can then be formed on the surface of the said dielectric layer. Metal gate electrode and gate dielectric layer can be formed on the metal layer and dielectric layer. The cover layer, the barrier layer and the quantum well can then be etched to form recessed source and drain regions. Such a quantum well device can have better performance and reliability.