Complementary HFET Gate Implantation for Low-Resistance Etching
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Solution Overview
Problem
The Planar Optoelectronic Technology (POET) faces challenges in controlling etching operations for fabricating optoelectronic devices, particularly in removing the etch stop layer and exposing the heavily doped p-type layer due to issues with etchant choice, temperature control, and selectivity reliability.
Innovation Solution
The method involves forming an integrated circuit with a plurality of semiconductor layers, including n-type and p-type layers, where p-type ions are implanted into the exposed second p-type layer to form a p-type gate region, and n-type ions are used to form source and drain regions, aiding in minimizing gate resistance for high-performance operation of complementary HFET devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If wet etching is used to remove the etch stop layer and expose the heavily doped p-type layer, then the etching operation can be performed, but the control of etching depth and selectivity becomes difficult due to issues with etchant choice, temperature control, and reliability
Solution Approach 1:
The etching process is divided into two distinct stages: first, dry etching is used to etch down to a predetermined depth close to the etch stop layer; second, wet etching is used to complete the etching by removing the etch stop layer. This segmentation allows each etching method to be optimized for its specific function, improving overall control and reliability.
Solution Approach 2:
The dry etching step is performed in advance to remove the majority of the etch stop layer and expose a predetermined portion of the heavily doped p-type layer before the wet etching step. This preliminary action reduces the burden on the wet etching process and improves the reliability of the overall etching operation.
2Manufacturing precision
If multiple etching operations are performed to expose the heavily doped p-type layer, then the etch stop layer can be removed, but the fabrication process complexity increases due to multiple dry and wet etching procedures
Solution Approach 1:
The combined dry and wet etching process serves multiple functions: dry etching provides precise depth control and removes the majority of the etch stop layer, while wet etching completes the removal and ensures full exposure of the heavily doped p-type layer. This multi-functional approach achieves both precision and completeness in a systematic manner.
Solution Approach 2:
The etch stop layer serves as an intermediary element that facilitates the fabrication process. It is designed to be selectively removed by the combined etching process to expose the heavily doped p-type layer, which then serves as a stop layer for subsequent ion implantation operations. This intermediary structure enables precise control of the fabrication process.
3Reliability
If ion implantation is used to form p-type gate region and n-type source/drain regions, then gate resistance is reduced for high-performance operation, but the fabrication process becomes more complex
Solution Approach 1:
Ion implantation is applied selectively to different regions of the semiconductor structure: p-type ions are implanted into the exposed second p-type layer to form the gate region, while n-type ions are implanted into the non-inverted n-type modulation doped quantum well structure to form source and drain regions. This localized application of different ion types optimizes the electrical properties of each region while maintaining process control.
Solution Approach 2:
The etching operation to expose the heavily doped p-type layer is performed in advance of the ion implantation step. This preliminary exposure creates the necessary conditions for subsequent p-type ion implantation to form the gate region, ensuring that the implantation process can proceed with precise control and optimal results.
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 effectively controls ion implant operations to reduce gate resistance, enabling high-performance operation of complementary HFET devices and improving the fabrication precision of optoelectronic devices.
Implementation Method 1
P-type ions are implanted into the exposed second p-type layer to form a p-type gate implanted region
Implementation Method 2
n-type ions are used to form source and drain regions
Data Source
AI summary
Integrated circuitry is fabricated from semiconductor layers formed on a substrate, which include at least one n-type layer, an inverted p-type modulation doped quantum well (mod-doped QW) structure, a non-inverted n-type mod-doped QW structure, and at least one p-type layer including a first P+-type layer formed below a second P-type layer. An etch operation exposes the second p-type layer. P-type ions are implanted into the exposed second p-type layer. A gate electrode of a n-channel HFET device is formed in contact with the p-type ion implanted region. Source and drain electrodes of the n-channel HFET device are formed in contact with n-type ion implanted regions formed in contact with the n-type mod-doped QW structure. P-channel HFET devices, complementary BICFET devices, stacked complementary HFET devices and circuits and/or logic gates based thereon, and a variety of optoelectronic devices and optical devices can also be formed as part of the integrated circuitry.