Recess Sidewall Photosensing Structure for Low-Dark-Current Photodetectors
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Solution Overview
Problem
Existing semiconductor device structures face challenges in reducing defects and dark current due to lattice mismatch and oxidation, which affect the performance and reliability of photodetectors.
Innovation Solution
A semiconductor device structure is formed with a photo-sensing structure epitaxially grown on the sidewalls of a recess, where the bottom is spaced apart, and a semiconductor cap is grown in-situ to minimize lattice mismatch and oxidation, reducing defects and dark current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the photo-sensing structure is formed using conventional fabrication techniques, then the manufacturing process is simpler, but lattice mismatch and oxidation occur leading to increased defects and dark current
Solution Approach 1:
The patent applies preliminary action by forming the photo-sensing structure epitaxially on the sidewalls of the recess before subsequent processing steps. This early formation ensures proper crystal orientation and minimizes lattice mismatch from the beginning, preventing defect propagation through later fabrication steps.
Solution Approach 2:
The patent employs an inert atmosphere during the epitaxial growth process to prevent oxidation of the photo-sensing structure. By conducting the epitaxial formation in a controlled inert environment, oxidation is minimized, reducing dark current and improving photodetector reliability without adding complex post-processing steps.
2Manufacturing precision
If the photo-sensing structure is grown epitaxially on recess sidewalls with spaced bottom, then crystalline quality improves and defects reduce, but the manufacturing process becomes more complex
Solution Approach 1:
The patent transitions from planar growth to three-dimensional sidewall growth by forming the photo-sensing structure epitaxially on the vertical sidewalls of the recess rather than on a flat surface. This dimensional change enables better crystalline quality through controlled epitaxial propagation while the recess geometry provides natural definition for the structure formation.
Solution Approach 2:
The patent applies local quality by creating a spaced bottom configuration where the photo-sensing structure is formed only on the sidewalls and intentionally separated from the recess bottom. This localized formation on specific surfaces (sidewalls only) with controlled spacing optimizes crystalline quality in the active regions while simplifying the overall process compared to complete filling approaches.
3Area of stationary object
If the photo-sensing structure is formed closer to the recess bottom, then device area is reduced, but misfit defects and dark current increase
Solution Approach 1:
The patent introduces the recess structure as an intermediary element that mediates between the photo-sensing structure and the substrate. The recess provides a controlled geometry that allows the photo-sensing structure to be positioned optimally on the sidewalls with appropriate spacing from the bottom, reducing mechanical stress and misfit defects that would otherwise increase dark current, while maintaining compact device area.
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 solution significantly improves the crystalline quality, reduces defects, and enhances the sensitivity and reliability of photodetectors by minimizing misfit defects and dark current.
Implementation Method 1
a photo-sensing structure is formed over sidewalls of the recess... a semiconductor cap is grown in-situ
Implementation Method 2
A photodetector is an optoelectronic device that is configured to receive photons of incident radiation and convert the photons into an electrical signal
Data Source
AI summary
A semiconductor device structure and a formation method are provided. The method includes receiving a substrate, and the substrate has a dielectric layer and a semiconductor layer over the dielectric layer. The method also includes forming a p-type doped region and an n-type doped region in the semiconductor layer. The method further includes partially removing the semiconductor layer and the dielectric layer to form a recess exposing portions of the p-type doped region and the n-type doped region. In addition, the method includes forming a photo-sensing structure over sidewalls of the recess, and the photo-sensing structure is spaced apart from a bottom of the recess.