Image Sensor Pixel Recess Structure for Dislocation Control
Find Innovative SolutionsGenerate Solutions
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 introduce stress and degrade electrical and optical properties.
Innovation Solution
The method involves forming recesses in the silicon substrate with modified profiles, such as curve-based bottom surfaces or protruded patterns, to aggregate dislocation defects at the bottom portion, and using doped dielectric layers to constrain them, followed by epitaxial growth of non-silicon semiconductor materials, which reduces threading dislocation density and minimizes their impact on the active regions of the device.
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 increase
Solution Approach 1:
The patent divides the semiconductor structure into distinct regions: a first semiconductor material region (silicon) and a second semiconductor material region (non-silicon material). This segmentation allows each material to be optimized for its specific function while managing the interface defects through controlled boundaries and isolation structures.
Solution Approach 2:
The patent introduces intermediary structures at the interface between different semiconductor materials, including isolation structures and transition regions. These intermediaries act as buffers to reduce the direct impact of lattice mismatch and dislocation propagation between the silicon substrate and non-silicon semiconductor layers.
2Ease of manufacture
If non-silicon materials are integrated into silicon process, then manufacturing cost is reduced, but manufacturing precision deteriorates
Solution Approach 1:
The patent applies different material compositions and structural characteristics to different regions of the device. The first semiconductor material is used in regions requiring specific electrical properties, while the second semiconductor material is used in regions requiring different optical or electrical characteristics. This local differentiation allows optimization of both manufacturing cost and precision in each region.
Solution Approach 2:
The patent utilizes changes in material parameters (such as band gap, lattice constant, and crystal structure) to manage defect propagation. By carefully selecting and transitioning between materials with different parameters, the patent controls dislocation density and maintains manufacturing precision while benefiting from cost-effective non-silicon materials.
3Adaptability or versatility
If lattice mismatch is present between semiconductor materials, then material diversity is achieved, but threading dislocation defects increase
Solution Approach 1:
The patent addresses threading dislocation defects by transitioning from a two-dimensional planar interface to a three-dimensional structured interface. Isolation structures and tapered transition regions are introduced to manage dislocation propagation paths, effectively adding a vertical dimension to defect management and reducing the impact of lattice mismatch.
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 image sensor devices by minimizing their negative impact on electrical and optical properties.
Implementation Method 1
The pixels are formed by epitaxially growing a non-silicon semiconductor material in the plurality of openings
Implementation Method 2
forming recesses in the silicon substrate with modified profiles, such as curve-based bottom surfaces or protruded patterns, to aggregate dislocation defects at the bottom portion
Implementation Method 3
using doped dielectric layers to constrain them
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.