Bonded Wafer Solar Cell Chip Integration for Low-Cost Drive Circuits
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Solution Overview
Problem
Existing methods struggle to produce an electronic device with a drive circuit, solar cell structure, and capacitor-function portion in one chip while maintaining a compact size and suppressing production costs, particularly due to issues with lattice mismatch and high epitaxial growth costs.
Innovation Solution
A method involving bonding a first wafer with solar cell structures and a second wafer with drive circuits and capacitor-function laminated portions, followed by wiring and dicing to create a compact electronic device with a solar cell structure, diode circuits, and capacitor-function portions, using a thermosetting adhesive to facilitate low-temperature bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a Si-based solar cell is used for optical wireless power receiving, then the device can be fabricated with existing processes, but the power receiving efficiency is low and a large area is required
Solution Approach 1:
The patent merges the solar cell structure and drive circuit into a single integrated chip by forming the solar cell on the same substrate as the drive circuit, eliminating the need for separate solar cell devices and reducing overall device area. This integration allows the solar cell and circuit to share the same fabrication process and physical space.
Solution Approach 2:
The patent transitions from a planar arrangement where the solar cell and drive circuit are separate components to a three-dimensional integrated structure where the solar cell is formed on the substrate and the drive circuit is formed over or around it, utilizing vertical stacking and layered structures to reduce footprint area.
2Productivity
If epitaxial growth of a compound semiconductor solar cell on a Si substrate is attempted, then the power receiving efficiency can be raised, but lattice mismatch becomes large requiring buffer layers and increasing epitaxial cost
Solution Approach 1:
The patent combines the solar cell structure and drive circuit into a single integrated fabrication process on one substrate, eliminating the need for separate epitaxial growth steps for compound semiconductors. This integration allows the use of standard Si substrate fabrication processes throughout, reducing manufacturing complexity and cost while maintaining functionality.
Solution Approach 2:
The patent uses a Si substrate that can be easily fabricated using standard, inexpensive semiconductor processing techniques rather than requiring expensive compound semiconductor epitaxial growth. The Si substrate serves as a cost-effective base that can be mass-produced and reused, reducing the overall manufacturing cost of the device.
3Productivity
If epitaxial growth is carried out in an impurity atmosphere for Si, then the solar cell can be formed, but substrate contamination increases and process design becomes difficult
Solution Approach 1:
The patent segments the device into distinct functional regions on the substrate, with the solar cell structure formed in one area and the drive circuit formed in another area. This spatial separation allows different fabrication processes to be applied to each region independently, reducing the risk of contamination spreading between functional components.
Solution Approach 2:
The patent merges the solar cell and drive circuit into a single integrated structure formed on the same substrate using combined fabrication processes. This integration allows the use of clean, controlled Si substrate processing throughout, avoiding the need for impurity atmospheres and reducing substrate contamination while maintaining both functional elements.
4Area of stationary object
If a solar cell structure and drive circuit are formed in one chip, then the device area can be reduced, but manufacturing complexity increases
Solution Approach 1:
The patent merges the solar cell structure and drive circuit into a single integrated chip fabrication process, where both components are formed on the same substrate using combined photolithography, deposition, and etching steps. This integration reduces the number of separate manufacturing steps and component assembly operations, thereby reducing overall manufacturing complexity despite the increased functional integration.
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
The method enables the production of a compact electronic device with reduced costs by allowing separate formation of solar cell and drive circuit components, reducing material and epitaxial costs, and maintaining functional integrity through low-temperature bonding.
Implementation Method 1
A power receiving device for optical wireless power receiving is a solar cell
Implementation Method 2
bonding the first wafer and the second wafer so that the plurality of solar cell structures, the plurality of diode circuits, the plurality of capacitor-function laminated portions, and the plurality of drive circuits are respectively superimposed
Data Source
AI summary
A method for producing an electronic device having a drive circuit including a solar cell structure, the method including the steps of: having a first wafer having solar cell structures on a starting substrate and a second wafer having drive circuits formed, so that either one of the first wafer or the second wafer has a plurality of independent diode circuits and capacitor-function laminated portions; obtaining a bonded wafer by bonding so that the solar cell structures, the diode circuits, the capacitor-function laminated portions, and the drive circuits are superimposed; wiring; and dicing the bonded wafer; thus creating a method for producing an electronic device including a drive circuit, a solar cell structure, and a capacitor-function portion in one chip and having a suppressed production cost; and such an electronic device.