In-Plane Magnetic Image Sensor Chip with Etch Pit
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Solution Overview
Problem
Existing magnetic image identification sensors face issues with low magnetic field sensitivity, large size, low resolution, high power consumption, and reduced output signals due to packaging materials and lead bonding, which increase the operating distance between the magnetic sensor and the image detection plane.
Innovation Solution
An in-plane magnetic image sensor chip is developed with a magnetoresistive sensor deposited on a Si substrate etch pit, connected directly to leads through pads or conducting posts, eliminating the need for packaging materials and reducing lead height, allowing direct contact with the magnetic image for enhanced signal strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If packaging materials and lead bonding are used to connect the magnetoresistive sensor, then the sensor can be protected and connected to external circuits, but the height of the lead or package material increases the operating distance between the magnetic sensor and the magnetic image detection plane, reducing the output signal
Solution Approach 1:
The patent removes the packaging material and traditional lead bonding structure from the system. The magnetoresistive sensor is directly exposed on the chip surface with no protective package material, and electrical connections are made through pads directly on the chip surface, eliminating the intermediate lead structure that increased operating distance.
Solution Approach 2:
The patent transitions from a three-dimensional packaged structure with leads extending vertically to a two-dimensional flat structure where the sensor and leads lie on the same chip surface plane. This dimensional change allows the sensor to be in direct contact with the magnetic image detection plane, minimizing the operating distance.
2Measurement precision
If the number of turns of the coil is increased to improve magnetic field sensitivity, then the induction current signal can be enhanced, but the size of the sensor increases and power consumption increases
Solution Approach 1:
The patent replaces the electromagnetic induction principle (requiring coil windings) with the magnetoresistive effect. The magnetoresistive sensor detects magnetic field changes through resistance changes in response to magnetic field orientation, eliminating the need for physical coil windings and associated mechanical complexity.
Solution Approach 2:
The patent changes the detection mechanism from electromagnetic induction to magnetoresistive effect. This parameter change allows sensitivity improvement through material and structural optimization of the magnetoresistive layer rather than increasing coil turns, thereby avoiding size and power consumption penalties.
3Measurement precision
If a permanent magnet assembly provides a larger bias magnetic field to compensate for increased operating distance, then the output signal can be maintained, but the device complexity and size increase
Solution Approach 1:
The patent eliminates the permanent magnet assembly from the system. By removing the package material and leads that created excessive operating distance, the sensor can directly detect the magnetic image without requiring additional bias magnetic field generation components.
Solution Approach 2:
The magnetoresistive sensor inherently provides the necessary bias field through its own magnetic layers and structure, eliminating the need for external permanent magnet assemblies. The sensor's magnetic tunnel junction or magnetoresistive layer generates the required magnetic field for operation.
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 solution achieves stronger output signals and reduced power consumption by minimizing the distance between the sensor and the magnetic image, improving sensitivity and resolution while eliminating the need for packaging materials.
Implementation Method 1
a magnetoresistive sensor deposited on the bottom surface of the etch pit
Implementation Method 2
The magnetoresistive sensor is one of Hall, AMR, GMR or TMR magnetoresistive sensors
Implementation Method 3
uses the principle of electromagnetic induction to induce an induction current in the coil according to a magnetic flux change
Data Source
Figure 1~3
Figure 4(a)~4(g)
Figure 5(a)~6
AI summary
Disclosed is a low fly height in-plane magnetic image sensor chip. This sensor chip comprises a Si substrate (1) with a pit (2) on the surface (4), a magnetoresistive sensor (5), and an insulating layer (6). The magnetoresistive sensor (5) is located on the bottom surface (3) of the pit (2) in the Si substrate (1). The insulating layer (6) is located above the magnetoresistive sensor (5). The magnetic image surface detected during operation is coplaner or parallel with the surface of the Si substrate (1) surface (3). The input and output ends of the magnetoresistive sensor (5) are connected with leads directly, or bonded with leads through pads (7(2)), or through a conducting post (8) and pads (7(2)) to form connections. And the flying height of the leads is lower than the height of the surface (4) of the Si substrate (1). This technical solution has several advantages, such as compact structure, high output signal, and direct contact with the magnetic image.