Laser-Treated Semiconductor Diode Single-Side Contact Fill Factor
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Solution Overview
Problem
Conventional silicon wafers have a substantial absorption depth for photons with wavelengths longer than 500 nm, leading to photon diffusion and cross-talk between pixels, resulting in reduced resolution, sensitivity, and efficiency in imaging applications due to limited fill factor and scattering from transistor and circuitry in front-side illumination imagers.
Innovation Solution
The development of laser-treated semiconductor diodes with single-side electrical contacts on silicon material, where a laser-treated region enhances absorption and reduces recombination, allowing for improved fill factor and quantum efficiency, especially for wavelengths longer than 900 nm, by extending the effective absorption length and minimizing surface recombination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional silicon wafers are used with standard depth, then manufacturing is simple, but photons with wavelengths greater than 500 nm cannot be absorbed effectively
Solution Approach 1:
The patent applies parameter changes by modifying the optical properties of the silicon surface through laser treatment. The laser creates a textured surface with enhanced light trapping capabilities, changing how photons interact with the silicon without requiring increased wafer depth. This allows effective absorption of photons with wavelengths greater than 500 nm while maintaining standard wafer dimensions.
2Use of energy by moving object
If deep collection elements are designed to absorb photons, then absorption efficiency improves, but photoelectrons diffuse to adjacent pixels causing cross talk
Solution Approach 1:
The patent applies local quality by creating localized laser-treated regions that enhance absorption specifically at the pixel surface. The laser treatment is applied in a controlled manner to specific areas, creating local variations in optical properties that improve photon capture without requiring deep collection elements that would cause electron diffusion and cross-talk between adjacent pixels.
3Adaptability or versatility
If front side illumination is used with transistors and circuitry, then device functionality is achieved, but light scatters off circuitry causing optical loss
Solution Approach 1:
The patent applies preliminary action by treating the silicon surface with laser before the pixels are fully fabricated. This pre-treatment creates an enhanced light-trapping surface structure that directs incident light more effectively toward the active pixel regions, preventing scattering off transistors and circuitry before the light reaches the photodetection layer.
4Ease of operation
If bussing and addressing circuits are fabricated around substrate layers, then device operation is enabled, but pixel fill factor is reduced
Solution Approach 1:
The patent applies dimensionality change by moving the laser treatment to the surface dimension rather than requiring additional depth or lateral space. The laser-created surface texture enhances optical performance in the vertical dimension, allowing bussing and addressing circuits to be fabricated around substrate layers without compromising pixel fill factor, as the optical enhancement occurs at the surface level rather than consuming additional 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
This approach achieves a quantum efficiency greater than 80% for light wavelengths longer than 900 nm and an absorptance greater than 80% for wavelengths longer than 800 nm, with a fill factor greater than 90%, reducing blurring and increasing sensitivity and efficiency in imaging devices.
Implementation Method 1
The laser treat region can be formed in the first region by a pulsed laser
Implementation Method 2
The laser treated region can be formed within the first region such that charge carriers are collected on the second side of the bulk semiconductor material. The laser treat region can be formed in the first region by a pulsed laser while simultaneously being doped with a first dopant. In some aspects, the laser treated region may be an enhanced absorption region.
Implementation Method 3
The development of laser-treated semiconductor diodes with single-side electrical contacts on silicon material, where a laser-treated region enhances absorption and reduces recombination
Data Source
AI summary
The present disclosure provides systems and methods for configuring and constructing a single photo detector or array of photo detectors with all fabrications circuitry on a single side of the device. Both the anode and the cathode contacts of the diode are placed on a single side, while a layer of laser treated semiconductor is placed on the opposite side for enhanced cost-effectiveness, photon detection, and fill factor.