Image Sensor Pixel Recesses for Lattice-Mismatch Defect Confinement
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Solution Overview
Problem
Integrating non-silicon semiconductor materials into silicon wafers results in defects such as dislocation defects, which degrade the performance of semiconductor devices such as photodectors, diodes, and many other semiconductor devices, such as photodetectors, diodes, light-emitting diodes, transistors, latches, and many other semiconductor devices, due to lattice mismatch and dislocation defects during epitaxial growth, leading to poor performance and premature failure.
Innovation Solution
The method involves forming recesses in the silicon substrate with modified profiles, such as curve-based bottom surfaces and sidewalls covered by doped dielectric layers, to constrain dislocation defects at the bottom portion, followed by epitaxial growth of non-silicon semiconductor materials, and thinning the silicon substrate to minimize dislocation defects in the active regions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-silicon semiconductor materials are integrated into silicon wafers, then the performance of semiconductor devices is improved, but dislocation defects occur due to lattice mismatch
Solution Approach 1:
The patent applies preliminary action by forming recesses with modified profiles (curve-based bottom surfaces) before epitaxially growing the non-silicon semiconductor material. This pre-prepared structure constrains dislocation defects to the bottom portion of the semiconductor layer, preventing them from propagating into the active regions and degrading device performance.
Solution Approach 2:
The patent uses doped dielectric layers as intermediaries, forming them on the sidewalls of the recesses before epitaxial growth. These dielectric layers act as barriers that constrain dislocation defects laterally, preventing their propagation into the active regions while allowing the non-silicon semiconductor material to be grown with improved crystalline quality.
2Adaptability or versatility
If epitaxial growth of non-silicon semiconductor materials is performed, then device functionality is enhanced, but dislocation defects propagate through the material
Solution Approach 1:
The patent segments the semiconductor layer into distinct regions: a bottom portion where dislocation defects are constrained and accumulated, and an upper active region with high crystalline quality. The recess structure with doped dielectric sidewalls creates this segmentation, allowing the epitaxially grown material to have different quality characteristics in different zones.
Solution Approach 2:
The patent applies local quality by creating different structural and crystalline properties in different regions of the semiconductor layer. The bottom portion of the recess contains dislocation defects with constrained propagation, while the upper active region maintains high crystalline quality suitable for device operation. The modified recess profile and doped dielectric layers enable this spatial differentiation.
3Ease of manufacture
If standard silicon wafer processing is used, then manufacturing cost is reduced, but integration of non-silicon materials becomes difficult
Solution Approach 1:
The patent merges the fabrication of non-silicon semiconductor devices with standard silicon CMOS processing. By forming recesses with modified profiles and using doped dielectric layers that are compatible with existing silicon processing, the patent enables co-fabrication of non-silicon photodetectors and silicon circuitry in a unified process flow, reducing overall manufacturing complexity and cost.
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 method significantly reduces dislocation defects in the active regions of semiconductor devices, enhancing their performance and longevity by constraining dislocation defects at the bottom portion of the semiconductor layer, thereby improving the device's performance and reliability.
Implementation Method 1
epitaxial growth of non-silicon semiconductor materials
Implementation Method 2
constrain dislocation defects at the bottom portion
Implementation Method 3
significantly reduces dislocation defects in the active regions
Data Source
AI summary
A method includes forming a plurality of openings extending into a substrate from a front surface of the substrate. The substrate includes a first semiconductor material. Each of the plurality of openings has a curve-based bottom surface. The method includes filling the plurality of openings with a second semiconductor material. The second semiconductor material is different from the first semiconductor material. The method includes forming a plurality of pixels that are configured to sense light in the plurality of openings, respectively, using the second semiconductor material.