Hybrid GaAs-Si Magnetic Sensor Chip
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Solution Overview
Problem
Magnetic field sensors made from silicon have low sensitivity and reliability due to mechanical stress from different thermal expansion coefficients when using discrete combinations of sensing devices and integrated electronics, and existing solutions are costly and prone to reliability issues.
Innovation Solution
A hybrid semiconductor chip with a magnetic sensing element made from a high mobility material like GaAs and an electronic circuit made from silicon, using an adhesive layer and transfer printing to mount and electrically connect the sensing element, allowing for higher sensitivity and speed while minimizing mechanical stress and production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a magnetic sensing element is made from silicon, then the production cost is low and manufacturing is easy, but the sensitivity and speed are insufficient due to low electron mobility
Solution Approach 1:
The patent divides the magnetic sensor into two separate components manufactured on different wafers: a magnetic sensing element made from high-mobility material (GaAs, InSb, etc.) on a second wafer, and an electronic circuit made from silicon on a first wafer. This segmentation allows each component to be optimized for its specific function - the sensing element for high sensitivity and the circuit for cost-effective mass production - while maintaining the overall system benefits of both approaches.
2Measurement precision
If discrete combinations of sensing devices and integrated electronics are assembled side-by-side on a carrier plate, then the sensitivity and speed requirements are met, but mechanical stress occurs due to different coefficients of thermal expansion leading to reliability problems
Solution Approach 1:
The patent merges the magnetic sensing element and electronic circuit onto a single semiconductor chip substrate. The sensing element is transferred from a second wafer to a first wafer containing the electronic circuit, creating an integrated hybrid structure. This merging eliminates the mechanical stress and reliability issues associated with discrete side-by-side assemblies while maintaining the sensitivity benefits of high-mobility materials.
Solution Approach 2:
The patent introduces an adhesive layer as an intermediary between the magnetic sensing element and the electronic circuit. This adhesive layer serves as a mediator that bonds the two different materials together, accommodating their different thermal expansion coefficients and preventing mechanical stress while enabling reliable electrical and mechanical connection.
3Measurement precision
If compound semiconductor layers are transferred onto a processed Si chip using existing methods, then the sensitivity is improved, but the production cost increases and the process is complex
Solution Approach 1:
The patent performs preliminary actions by separately manufacturing and preparing the magnetic sensing element on a second wafer before transferring it to the first wafer containing the electronic circuit. The landing area on the first wafer is prepared with an adhesive layer in advance. This preliminary preparation simplifies the transfer process and enables high-volume production by avoiding complex in-situ processing steps.
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 hybrid chip achieves higher sensitivity and speed than silicon-based sensors, with reduced mechanical stress and production costs, enabling reliable and cost-effective high-volume production for applications like compass and current sensing.
Implementation Method 1
An adhesive layer is present between the magnetic sensing element and the electronic circuit
Implementation Method 2
Hall devices as magnetic sensors
Data Source
Figure 1~2
Figure 3(a)~3(h)
Figure 4(a)~5(c)
AI summary
A semiconductor chip (100) for measuring a magnetic field comprises a magnetic sensing element (110) which is mounted on, and connected with, an electronic circuit (120). The electronic circuit is produced in a first technology and/or first material, and the magnetic sensing element is produced in a second technology and/or second material different from the first technology/material. Preferably, a compound semiconductor Hall element is adhesively bonded onto a silicon CMOS chip.