Embedded Wafer-Level Optical Sensor Packaging for CTE Robustness
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Solution Overview
Problem
Semiconductor device packages face challenges in reducing the likelihood of failure due to differences in coefficients of thermal expansion (CTEs) of various materials, leading to cracking and misalignment issues, especially with the use of adhesives and caps in existing designs.
Innovation Solution
The solution involves embedding a light emitter within a sensor die and using optically transmissive structures and a molding compound to create semiconductor packages with reduced profile and thickness, eliminating the need for a cap and substrate, thereby minimizing CTE-related issues and enhancing robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cap is coupled to the substrate using adhesive and pick and place machine, then the light sensor and light emitter are protected, but it is difficult to achieve precise tolerances and the adhesive becomes a point of weakness under thermal expansion
Solution Approach 1:
The patent merges the cap and substrate into a single integrated sensor die structure. The optically transmissive layers are formed directly on the sensor die using deposition techniques, eliminating the need for separate cap assembly with adhesive. This integration removes the adhesive layer that becomes a weakness point under thermal expansion and eliminates the pick and place process that cannot achieve precise tolerances.
Solution Approach 2:
The patent introduces a resin material as an intermediary to fill voids and provide mechanical support between the optically transmissive layers and the sensor die. This resin acts as a buffer that accommodates thermal expansion differences while maintaining structural integrity and optical performance, replacing the problematic adhesive-coupled cap structure.
2Adaptability or versatility
If cap, lenses, and substrate are made of different materials with different CTEs, then various functions are achieved, but they expand and contract by different amounts causing cracks and breaks
Solution Approach 1:
The patent applies local quality by forming optically transmissive layers with specific material properties only where needed on the sensor die surface. The resin is selectively placed in void regions to provide local mechanical support and CTE matching. This localized approach allows different materials to be used in different regions without creating global stress issues, as each material is positioned where it provides the most benefit.
Solution Approach 2:
The patent creates a composite structure where the sensor die, optically transmissive layers, and resin work together as an integrated system. The resin acts as a compliant intermediate material that bridges the CTE mismatch between the rigid sensor die and the optically transmissive layers. This composite approach allows the use of materials with different CTEs while preventing cracks through the resin's ability to accommodate differential expansion and contraction.
3Ease of operation
If light emitter and light sensor are formed in separate dies with stacked arrangement and space between cap and die surface, then functionality is achieved, but the overall profile and thickness increase
Solution Approach 1:
The patent merges the light emitter and light sensor into a single integrated sensor die structure. Both photodetectors and the light-emitting element are formed on the same die substrate, eliminating the need for separate stacked dies. This integration dramatically reduces the overall profile and thickness while maintaining the time-of-flight sensing functionality through coordinated operation of the integrated components.
Solution Approach 2:
The patent transitions from a three-dimensional stacked arrangement of separate dies to a two-dimensional integrated layout on a single sensor die. The light emitter and photodetectors are arranged in planar configurations on the same die surface, with optically transmissive layers formed above them. This dimensional change from vertical stacking to horizontal integration significantly reduces the z-direction thickness while preserving functional performance.
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 reduces the likelihood of failure due to thermal expansion differences, increases manufacturing yield, and maintains functionality even with minor misalignments, resulting in more robust and cost-effective semiconductor device packages.
Implementation Method 1
The light emitter is positioned within an opening in the sensor die and is surrounded by a resin
Implementation Method 2
Optically transmissive structures are placed on or formed on the light emitter and the light sensor to cover and protect the light sensor and the light emitter
Implementation Method 3
A bonding wire is in the optically transmissive structure on the light emitter and couples the light emitter to an electrical connection in the sensor die
Implementation Method 4
a molding compound is formed on sidewalls of the optically transmissive structures, on a surface of the sensor die, and a surface of the molding compound is substantially coplanar with surfaces of the optically transmissive structures
Data Source
AI summary
The present disclosure is directed to a sensor die with an embedded light sensor and an embedded light emitter as well as methods of manufacturing the same. The light emitter in the senor die is surrounded by a resin. The sensor die is incorporated into semiconductor device packages as well as methods of manufacturing the same. The semiconductor device packages include a first optically transmissive structure on the light sensor of the sensor die and a second optically transmissive structure on the light emitter of the sensor die. The first optically transmissive structure and the second optically transmissive structure cover and protect the light sensor and the light emitter, respectively. A molding compound is on a surface of a sensor die and covers sidewalls of the first and second optically transmissive structures on the sensor die.