Etch Stop Layer Offset for Semiconductor Integration
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Solution Overview
Problem
Current semiconductor integrated circuit technologies face challenges in efficiently fabricating optoelectronic and electronic devices with high performance and integration capabilities using inversion quantum-well channel structures, particularly in achieving precise layer formation and contact formation for optimal device functionality.
Innovation Solution
The proposed solution involves a specific layer structure and fabrication method using III-V semiconductor materials, including n-type and p-type modulation doped quantum well structures, etch stop layers, and ion implantation for forming ohmic contacts and ion-implanted contact regions, with citric acid as an etchant to stop etching at precise layers, enabling the formation of mesa structures for gate and collector regions in HFET devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple device types (optoelectronic and electronic devices) are fabricated simultaneously on a common substrate using the same fabrication sequence, then productivity and integration are improved, but manufacturing precision and device performance deteriorate due to incompatible fabrication requirements
Solution Approach 1:
The patent divides the fabrication process into distinct sequences: a first fabrication sequence for optoelectronic devices and a second fabrication sequence for electronic devices. This segmentation allows each device type to receive specialized processing optimized for its specific requirements, resolving the conflict between integrated fabrication and device performance
Solution Approach 2:
The patent performs preliminary actions by forming specific layer structures (including etch stop layers with different etch selectivities) before fabrication begins. These pre-formed structures enable subsequent selective etching processes that can target different device regions with different precision requirements, allowing high-performance fabrication for both device types
2Manufacturing precision
If selective etching is used to form different device structures with different etch selectivities, then manufacturing precision is improved, but device complexity increases due to multiple etch stop layers and offset configurations
Solution Approach 1:
The patent introduces etch stop layers as intermediary structures between functional layers. These intermediary layers have specific etch selectivities that enable precise control over etching depth and termination, allowing selective formation of different device structures without requiring complex direct etching of underlying layers
Solution Approach 2:
The patent implements offset configurations where etch stop layers are positioned at different lateral locations for different device types (e.g., offset etch stop layers for optoelectronic devices versus aligned etch stop layers for electronic devices). This local differentiation allows each device region to have optimized etching characteristics tailored to its specific structural requirements
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 allows for the precise formation of optoelectronic and electronic devices with improved performance and integration, enabling the creation of high-performance transistors and optoelectronic devices like phototransistors and thyristors with enhanced conductance modulation and optical functionality.
Implementation Method 1
etching the semiconductor device with an etchant that automatically stops at the fifth etch stop layer
Implementation Method 2
self-aligned n-type and p-type channel contacts formed by ion implantation
Data Source
AI summary
A semiconductor device includes a series of layers formed on a substrate, including a first plurality of n-type layers, a second plurality of layers that form a p-type modulation doped quantum well structure (MDQWS), a third plurality of layers disposed between the p-type MDQWS and a fourth plurality of layers that form an n-type MDQWS, and a fifth plurality of p-type layers. The first plurality of layers includes a first etch stop layer of n-type formed on an n-type contact layer. The third plurality of layers includes a second etch stop layer formed above the p-type MDQWS and a third etch stop layer formed above and offset from the second etch stop layer. The fifth plurality of layers includes a fourth etch stop layer of p-type formed above the n-type MDQWS and a fifth etch stop layer of p-type doping formed above and offset from the fourth etch stop layer.