Multi-tiered Metal Spacers for Stacked Microelectronic Device Alignment
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Solution Overview
Problem
Conventional stacked microelectronic devices face challenges with non-rigid epoxy spacers that do not ensure uniform spacing between dies, leading to misalignment and instability, and require additional equipment and processing steps for silicon spacers.
Innovation Solution
The use of multi-tiered metal spacers, formed during the wire bonding process, provides incompressible and stable spacing between dies, eliminating the need for additional equipment and processing, and can be placed adjacent to wire bonds or at the edges to maintain die parallelism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If epoxy spacers are used to space apart stacked dies, then the packaging process can be simplified, but the spacers are not rigid until cured and thus the second dies may not be uniformly spaced apart from the corresponding first dies
Solution Approach 1:
The patent changes the physical state parameter of the spacer material from soft/curable (epoxy) to rigid (metal), eliminating the curing process and ensuring uniform spacing immediately upon placement. The metal spacers maintain their dimensional stability and rigidity without requiring chemical transformation.
Solution Approach 2:
The patent replaces expensive silicon spacers with inexpensive metal spacers that can be formed directly from wire bonding material. These metal spacers serve their spacing function and can be integrated into the final package structure, eliminating the need for costly precision-spacer fabrication and handling equipment.
2Manufacturing precision
If silicon spacers are used to ensure precise spacing between dies, then uniform spacing is achieved, but additional equipment and processing steps are required
Solution Approach 1:
The patent merges the spacing function with the existing wire bonding process by forming metal spacers from the wire bonding material itself. This integration eliminates the need for separate spacer fabrication, placement, and curing equipment, reducing device complexity while maintaining precision spacing through the rigid metal structure.
3Reliability
If wire bonds are used to electrically couple dies to interposer substrate, then electrical connection is achieved, but the wire bonds may interfere with die stacking alignment
Solution Approach 1:
The patent segments the wire bonding material into two distinct functional components: wire bonds for electrical connection and metal spacers for mechanical spacing and alignment. This segmentation allows wire bonds to be positioned away from critical alignment areas while metal spacers provide rigid structural support at corners and edges, eliminating interference between electrical and mechanical functions.
Data Source
Figure 1A~1B
Figure 2A
Figure 2B~2D
AI summary
Stacked microelectronic devices and methods of manufacturing stacked microelectronic devices are disclosed herein. In one embodiment, a method of manufacturing a microelectronic device includes forming a plurality of electrically isolated, multi-tiered metal spacers on a front side of a first microelectronic die, and attaching a back-side surface of a second microelectronic die to individual metal spacers. In another embodiment, the method of manufacturing the microelectronic device may further include forming top-tier spacer elements on front-side wire bonds of the first die.