Die Stack Alignment Channels for Precise Semiconductor Assembly
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Solution Overview
Problem
The challenge in semiconductor device packaging is aligning dies in a die stack and on a substrate with precision to ensure effective communication and prevent interference, as misalignment can lead to failed devices, especially with the increasing complexity of vertically stacked packages.
Innovation Solution
The use of channels formed on the dies through laser dicing or plasma etching, which serve as optical alignment features, allowing for precise alignment of dies within the stack and with the substrate, combined with optically visible alignment structures and tools for accurate positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple semiconductor dies are vertically stacked to increase processing power without increasing package footprint, then the functional capacity and processing power are improved, but the alignment precision requirements become more stringent and difficult to achieve
Solution Approach 1:
Alignment marks are formed on the dies during the wafer fabrication process before the dies are separated and stacked. This preliminary formation of alignment features eliminates the need for complex alignment operations during the stacking process, as the marks are already precisely positioned on each die relative to its bond pads and circuitry.
Solution Approach 2:
Optical alignment marks serve as intermediary reference features that facilitate the alignment process. These marks are imaged by alignment tools to determine the precise position and orientation of each die, enabling accurate stacking without requiring direct measurement of the delicate electrical connectors and bond pads.
2Ease of manufacture
If conventional alignment methods are used without dedicated alignment marks, then the manufacturing process is simpler, but the alignment accuracy is insufficient for vertically stacked packages
Solution Approach 1:
The alignment system is segmented into distinct components: alignment marks formed on each die during fabrication, optical fields for imaging the marks, and control systems for positioning. This segmentation allows the alignment function to be independently optimized without complicating the overall manufacturing process.
Solution Approach 2:
Alignment marks are essentially optical copies or reference representations of the die's electrical features (bond pads, circuitry). By creating these optical reference copies during wafer fabrication, the system enables precise alignment through optical imaging without requiring physical contact or complex mechanical measurement systems during stacking.
3Manufacturing precision
If alignment marks are formed on dies during wafer fabrication, then the alignment accuracy is improved, but the wafer fabrication process becomes more complex
Solution Approach 1:
The formation of alignment marks is merged with the existing wafer fabrication process. The alignment marks are created using standard photolithography and etching techniques that are already employed for forming the semiconductor circuitry, so no additional fabrication equipment or process steps are required.
Solution Approach 2:
The photolithography and etching processes used to form alignment marks serve multiple functions: they create the alignment reference features while also defining the die geometry and electrical features. This multi-functionality means that the same fabrication infrastructure is utilized for both alignment mark formation and device manufacturing, avoiding additional process complexity.
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 method enhances the accuracy and reliability of die alignment, improving the functionality and reducing the risk of device failure by ensuring precise vertical and rotational alignment, even with non-uniform edges, thereby increasing the processing power within a smaller footprint.
Implementation Method 1
channels formed on the dies through laser dicing
Implementation Method 2
channels formed on the dies through laser dicing or plasma etching
Data Source
AI summary
Semiconductor device assemblies having features that are used to align semiconductor dies, and associated systems and methods, are disclose herein. In some embodiments, a semiconductor device assembly includes substrate that has a top surface and an alignment structure at the top surface. A first die is disposed over the top surface of the substrate, and the first die has a first channel that extends between a top side and a bottom side of the first die. The first channel is vertically aligned with and exposes the alignment structure at the top surface of the substrate.