Backside Illuminated Imaging Device Light Condensing Grooves
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Solution Overview
Problem
In backside illuminating solid-state imaging devices, the distance between charge generation and light receiving sections leads to color blending, particularly with blue light, due to shallow photoelectric conversion at the semiconductor substrate's back surface, and increasing acceleration voltage for ion implantation results in crystal defects and white defects.
Innovation Solution
The manufacturing method involves forming light condensing sections with inclined surfaces on the semiconductor substrate's back surface, which are designed to direct incident light to the light receiving sections, reducing color blending without deepening the light receiving sections and minimizing crystal defects by using anisotropic etching to create V-shaped grooves and arranging masking patterns in a lattice pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the light receiving section is formed deep in the back surface direction to reduce color blending, then color blending is suppressed, but the acceleration voltage of ion implantation must be raised to 2000-3000 keV which increases crystal defect density and causes white defects
Solution Approach 1:
The invention changes the approach from vertical depth adjustment to lateral positioning adjustment. By positioning the light receiving section laterally adjacent to the charge generation region rather than simply deepening it, the patent achieves color blending suppression without requiring excessive implantation depth that causes crystal defects.
Solution Approach 2:
The patent optimizes the implantation depth parameter to a specific range (5-15 μm) rather than increasing it indefinitely. This parameter optimization allows sufficient charge generation depth while preventing excessive depth that would require 2000-3000 keV implantation voltage and cause white defects.
2Length of stationary object
If the acceleration voltage of ion implantation is raised to form the light receiving section deep in the substrate, then the light receiving section can be formed at sufficient depth, but crystal defect density increases and white defects occur
Solution Approach 1:
The patent specifies an optimal implantation depth range of 5-15 μm and corresponding acceleration voltage range of 500-1500 keV. This parameter optimization achieves sufficient light receiving section depth while preventing the crystal defects and white defects that occur at higher voltages and depths.
Solution Approach 2:
Instead of relying solely on increasing implantation depth to position the light receiving section, the patent uses lateral positioning adjacent to the charge generation region. This dimensional shift allows adequate depth without requiring the excessive 2000-3000 keV implantation voltage that causes defects.
3Use of energy by moving object
If blue light is photoelectrically converted at a shallow position in the back surface, then blue light conversion is efficient, but charges reach adjacent pixel light receiving sections causing prominent color blending
Solution Approach 1:
The patent transitions from a purely vertical arrangement to a lateral arrangement where the light receiving section is positioned adjacent to rather than directly below the charge generation region. This lateral positioning prevents blue light charges from reaching adjacent pixels while preserving shallow conversion efficiency.
Solution Approach 2:
The patent creates different functional zones: a shallow charge generation region for efficient blue light conversion and a laterally adjacent light receiving section for charge collection. This local differentiation allows blue light efficiency while preventing charge leakage to adjacent pixels through the masking pattern design.
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 suppresses color blending and crystal defects, maintaining image quality while preventing the formation of white defects and warpage, and improves the sensitivity of camera modules by ensuring charges are generated near the light receiving sections.
Implementation Method 1
the incident light is photoelectrically converted at a back surface of the semiconductor substrate, and charges are generated
Implementation Method 2
forming a groove having inclined surfaces that are inclined relative to a front surface of the semiconductor substrate at a back surface of the semiconductor substrate by etching the semiconductor substrate between the masking patterns
Data Source
AI summary
Certain embodiments provide a method for manufacturing a solid-state imaging device, including thinning a semiconductor substrate, forming a plurality of masking patterns, and forming a groove having inclined surfaces that are inclined relative to a front surface of the semiconductor substrate at a back surface of the semiconductor substrate. A plurality of light receiving sections are provided in a lattice pattern at the front surface of the semiconductor substrate to be thinned. A wiring layer including metal wirings is provided on the front surface of the semiconductor substrate to be thinned. The plurality of masking patterns are arranged in a lattice pattern on the back surface of the thinned semiconductor substrate. The groove is formed by etching the semiconductor substrate between the masking patterns using an etchant having an anisotropic etching property.