Self-Aligned Semiconductor Package for Under-Display Fingerprint Sensors
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Solution Overview
Problem
Conventional fingerprint sensors face challenges in reducing device size due to their optical systems and are difficult to integrate with electronic devices' front surfaces, especially when protective covers are present, and existing packaging methods are not suitable for stacking semiconductor chips or non-semiconductor structures.
Innovation Solution
A display-based fingerprint detection system using a display panel as a light source, with a prism surface and micro lens array to refract light from finger ridges and valleys, allowing for ambient light utilization and improved alignment and packaging of semiconductor packages with self-aligned structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional optical system including a prism, a specular mirror, and a lens is used to capture fingerprint images, then the fingerprint sensing function is achieved, but the volume of the electronic device increases considerably
Solution Approach 1:
The patent combines the fingerprint sensor with the display panel by integrating the optical system into the display structure. The display panel serves as both the display device and the light source for fingerprint capture, eliminating the need for separate optical components and reducing overall device volume.
Solution Approach 2:
The display panel performs multiple functions: it serves as the display device, the light source for fingerprint illumination, and the protective cover. This multi-functionality eliminates the need for separate components, thereby reducing device volume while maintaining fingerprint sensing capability.
2Strength
If the front surface of an electronic device is covered with a protective medium such as a glass cover to protect the display panel, then the display panel is protected, but it becomes difficult to attach a capacitive fingerprint sensor to the front surface
Solution Approach 1:
The patent merges the fingerprint sensor with the display panel by integrating it into the display structure. The sensor is positioned behind the glass cover, and the optical system is configured to capture light through the glass cover, allowing both protection and sensing functionality to coexist.
Solution Approach 2:
The optical system acts as an intermediary between the glass cover and the fingerprint sensor. It captures light that passes through the glass cover and transmits the optical information to the sensor, enabling the sensor to function through the protective medium without direct contact.
3Device complexity
If conventional packages designed to accommodate a single semiconductor chip are used, then the packaging structure is simple, but it is not suitable for stacking semiconductor chips or non-semiconductor structures
Solution Approach 1:
The patent segments the package structure into multiple functional layers, including a lower structure for the semiconductor chip, an optical structure layer, and an upper cover. This segmented design allows each layer to perform its specific function while enabling the stacking of multiple components within a single package.
Solution Approach 2:
The patent transitions from a two-dimensional single-chip layout to a three-dimensional stacked structure. By utilizing the vertical dimension, multiple semiconductor chips and non-semiconductor structures can be stacked and interconnected, increasing component density and package versatility.
4Manufacturing precision
If a machine vision system is used to align non-semiconductor structures with semiconductor chips, then alignment precision of several tens of micrometers is achieved, but it becomes difficult to align in structures where machine vision is not available or where the package must be sealed immediately after stacking
Solution Approach 1:
The patent implements self-alignment features directly on the semiconductor chip and non-semiconductor structure, such as alignment marks or mechanical interlocking structures. These features enable the components to align themselves during the stacking process without requiring external machine vision systems, simplifying the manufacturing process and enabling immediate sealing after stacking.
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
Enables efficient fingerprint image generation in low-light environments and facilitates the integration of fingerprint sensors on electronic devices' front surfaces, while also providing a suitable packaging solution for stacked semiconductor chips.
Implementation Method 1
a prism surface having alternately-arranged a plurality of prism valleys and a plurality of prism peaks and configured for refracting ray of light at various incidence angles
Implementation Method 2
an optical path extending layer being arranged below the micro lens array, and an image sensor being arranged below the optical path extending layer and configured for detecting rays of light that are refracted by the micro lens array
Data Source
AI summary
Semiconductor package having self-aligned structure disclosed. Semiconductor package includes a semiconductor chip having an active area and at least one marginal area that is located around the active area, wherein at least one alignment bar is arranged on the marginal area and a top structure being arranged on the semiconductor chip and having a groove being formed on a bottom surface, wherein the groove is configured for accommodating the alignment bar.