Hybrid Bonded Die Stack Structure for Reduced Vertical Spacing
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Solution Overview
Problem
Conventional die stack structures face challenges in reducing gap distances between neighboring dies, leading to lower production yields and cutting defects due to mechanical sawing processes that are not optimal for semiconductor materials like silicon, resulting in inefficient packaging and potential defects.
Innovation Solution
A die stack structure is developed using a hybrid bonding method without gap fill molds or adhesives, where the base die and component dies are directly bonded with a conductive-insulative hybrid bonding structure, allowing for a flat and uniform base die surface and a rougher uneven residual mold on the die stack, enabling reduced vertical spacing and improved adhesive strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If mechanical sawing process is used to separate dies from wafer, then cutting speed is improved, but cutting quality deteriorates due to defects in semiconductor materials
Solution Approach 1:
The patent replaces the mechanical sawing process with a chemical etching process using KOH solution to separate the base die from the wafer. This substitution eliminates the cutting defects caused by mechanical contact while maintaining efficient separation, directly resolving the contradiction between cutting speed and cutting quality.
2Stability of the object's composition
If gap fill mold is used to fill spaces between dies, then die spacing is improved, but device height increases due to vertical spacing requirements
Solution Approach 1:
The patent removes the gap fill mold from the die stack structure, extracting the unnecessary vertical spacing element. By eliminating this component, the device height is reduced while the die spacing is maintained through direct bonding of dies without requiring gap filling, thus resolving the contradiction between die spacing stability and device height.
Solution Approach 2:
The patent merges the base die and component dies through direct bonding without intervening gap fill molds. This combining approach eliminates the vertical spacing that would otherwise be required, reducing overall device height while maintaining proper die spacing through the bonding interface itself.
3Ease of manufacture
If conventional wafer to die bonding process is used, then manufacturing simplicity is improved, but production yield deteriorates due to insufficient gap distance control
Solution Approach 1:
The patent replaces the conventional mechanical sawing process with chemical etching using KOH solution. This substitution enables precise control of gap distances between dies during the wafer to die bonding process, improving production yield by preventing defects while maintaining manufacturing simplicity through a streamlined chemical process.
Data Source
AI summary
A die stack structure may include a base die having base contact pads insulated by a base protection patterns and a flat side surface, a die stack bonded to the base die and having a plurality of component dies on the base die such that each of the component dies includes component contact pads insulated by a corresponding component protection pattern, and a residual mold unevenly arranged on a side surface of the die stack such that the component dies are attached to each other by the residual mold.