Wafer-Level Sensor Packaging for Angular Alignment

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Solution Overview

Problem

Traditional chip level packaging of semiconductor sensors faces limitations in angular alignment accuracy, typically achieving only plus or minus two degrees, which is insufficient for precise measurements, especially as integrated circuit geometries shrink and the use of miniaturized sensors increases, necessitating more accurate and cost-effective packaging solutions.

Innovation Solution

The implementation of a wafer-level packaging technique that extends wafer fabrication to include device interconnection and protection, allowing for high-throughput and precise placement of sensors, achieving angular alignment accuracy of less than one tenth of a degree by bonding controller wafers to sensor wafers with precise alignment and forming conductive elements as input/output elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If traditional chip level packaging is used, then manufacturing process is simpler, but angular alignment accuracy is limited to plus or minus two degrees

Engineering Contradiction:

Improveangular alignment accuracyVSAvoidpackaging process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The packaging process is divided into two distinct stages: wafer-level packaging for achieving precise angular alignment, and subsequent die-level packaging for final assembly. This segmentation allows each stage to optimize for its specific function, with wafer-level processing providing the precision needed for angular alignment while die-level processing handles final integration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Angular alignment is established during wafer-level packaging before the dies are cut and packaged individually. This preliminary action of setting alignment at the wafer level ensures high precision (less than one tenth of a degree) is achieved before subsequent packaging steps, eliminating the need for realignment during die-level assembly.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If wafer level packaging is implemented, then angular alignment accuracy improves to less than one tenth of a degree, but device complexity increases

Engineering Contradiction:

Improveangular alignment accuracyVSAvoidpackaging ease

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

Multiple packaging operations are merged into a single wafer-level process. Alignment, bonding, and interconnection are all performed while the devices are still on the wafer substrate, combining what would traditionally be separate steps into one integrated process that achieves high precision efficiently.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The wafer structure itself provides the alignment reference and bonding surface. The wafer-level process utilizes the wafer's own geometry and features to establish precise angular alignment without requiring external alignment tools or complex positioning mechanisms during subsequent packaging steps.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If traditional packaging is used, then production cost is lower, but measurement precision is insufficient for miniaturized sensors

Engineering Contradiction:

Improvesensor measurement accuracyVSAvoidcost-effective production

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

Precise angular alignment is established during wafer-level packaging before the dies are cut and packaged individually. This preliminary action of setting alignment at the wafer level ensures high precision (less than one tenth of a degree) is achieved before subsequent packaging steps, eliminating the need for realignment during die-level assembly.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Inventive Principle:

Principle #1Segmentation

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 results in sensor packages with improved angular alignment accuracy, reduced size, enhanced electrical performance, and cost-effective production, addressing the limitations of traditional packaging methods by enabling precise and high-density packaging of miniaturized sensors.

Implementation Method 1

bonding controller wafers to sensor wafers with precise alignment

Methodology Applied

Scientific EffectWafer bonding: Welding

Data Source

PatentUS9165886B2Sensor packaging method and sensor packages

Publication Date: 2015.10.20 STMICROELECTRONICS INT NV

AI summary

A method (80) entails providing (82) a structure (117), providing (100) a controller element (102, 24), and bonding (116) the controller element to an outer surface (52, 64) of the structure. The structure includes a sensor wafer (92) and a cap wafer (94) Inner surfaces (34, 36) of the wafers (92, 94) are coupled together, with sensors (30) interposed between the wafers. One wafer (94, 92) includes a substrate portion (40, 76) with bond pads (42) formed on its inner surface (34, 36). The other wafer (94, 92) conceals the substrate portion (40, 76). After bonding, methodology (80) entails forming (120) conductive elements (60) on the element (102, 24), removing (126) material sections (96, 98, 107) from the wafers to expose the bond pads, forming (130) electrical interconnects (56), applying (134) packaging material (64), and singulating (138) to produce sensor packages (20, 70).