Image Sensor Pixel Openings for Dislocation Defect Isolation
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Solution Overview
Problem
The integration of non-silicon semiconductor materials into silicon wafers for image sensor devices often results in dislocation defects due to lattice mismatch, leading to poor performance and premature device failure, as these defects degrade the electrical and optical properties of the semiconductor material.
Innovation Solution
The method involves modifying the profile of recesses in the silicon substrate to aggregate dislocation defects at the bottom portion of the non-silicon semiconductor layer, which can be removed, thereby minimizing their impact on the active regions of the image sensor device. This is achieved by creating curve-based openings and using doped dielectric layers to constrain threading dislocation defects during epitaxial growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If non-silicon semiconductor materials are integrated into silicon wafers, then device performance is improved, but dislocation defects occur due to lattice mismatch
Solution Approach 1:
The patent segments the non-silicon semiconductor layer into multiple portions at different depths. The upper portion contains active device regions with minimized dislocation defects, while the lower portion aggregates dislocation defects that can be removed. This segmentation allows the device to benefit from non-silicon materials while isolating harmful defects to removable regions.
Solution Approach 2:
The patent extracts dislocation defects from the active device regions by allowing them to aggregate in lower, removable portions of the non-silicon semiconductor layer. These aggregated defects are then removed through selective etching or other removal processes, leaving clean active regions for device operation.
2Reliability
If recesses are modified to aggregate dislocation defects, then defect impact on active regions is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent performs preliminary modification of recess profiles before epitaxial growth of non-silicon semiconductor materials. By pre-shaping the recesses with curve-based bottom surfaces, the patent directs dislocation defects to aggregate in specific lower regions during subsequent material growth, preventing defects from reaching active device regions.
Solution Approach 2:
The patent uses doped dielectric layers as intermediary structures between the silicon substrate and non-silicon semiconductor materials. These intermediary layers help constrain and direct dislocation defect propagation, serving as a buffer that guides defects away from active regions while maintaining structural integrity.
3Reliability
If curve-based openings are created, then dislocation defects are constrained, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs curve-based bottom surfaces in recesses instead of flat or simple geometric shapes. These curved profiles are specifically designed to guide and constrain dislocation defects during epitaxial growth, directing them toward removable lower portions while maintaining manufacturability through controlled curvature rather than complex geometries.
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 significantly reduces dislocation defects in the epitaxially grown non-silicon semiconductor layers, enhancing the performance and reliability of the image sensor device by minimizing their negative impact on the active regions.
Implementation Method 1
filling the plurality of openings with a second semiconductor material. The second semiconductor material is different from the first semiconductor material. forming a plurality of pixels that are configured to sense light in the plurality of openings, respectively, using the second semiconductor material
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.