Die Stacking via Pneumatic Lift and Through-Hole Tray
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Solution Overview
Problem
Conventional die trays for semiconductor materials introduce significant drawbacks during processing, including particulate debris, damage to dies, and contamination, due to the flipping operation, which complicates subsequent bonding steps and reduces yield, especially as die thicknesses decrease.
Innovation Solution
The use of a die tray with through-holes allows for both top and bottom side processing of dies without flipping, utilizing pneumatic lift techniques to transfer and bond dies without flipping, thereby avoiding particulate debris and damage, and enabling low-cost, high-yield die-to-die stacking processes, including applications in DRAM stacks and other manufacturing processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If dies are flipped from one die tray to another die tray after processing, then the bottom sides of the dies can be exposed for bottom side processing, but particulate debris is produced and the dies may be damaged
Solution Approach 1:
Instead of flipping the dies over to access the bottom side, the patent inverts the approach by removing the die tray and using a support structure that allows access to the bottom side while the dies remain in their original orientation. The dies are held by their top surfaces and the bottom surfaces are accessible from below without requiring the dies to be flipped.
Solution Approach 2:
The patent introduces an intermediary support structure (such as a susceptor or support tray with openings) that holds the dies during processing. This intermediary structure allows processing equipment to access both the top and bottom sides of the dies without requiring the dies to be flipped, thereby avoiding the generation of particulate debris and damage associated with flipping operations.
2Ease of operation
If conventional die trays are used for handling semiconductor materials, then dies can be held and transferred, but significant drawbacks including particulate debris, damage to dies, and contamination are introduced
Solution Approach 1:
The patent extracts the problematic element (the solid die tray that causes flipping and contamination) from the system. Instead of using a conventional solid die tray, the invention uses a support structure with openings or a susceptor that allows the dies to be held securely while eliminating the source of particulate debris and damage. The support structure is removed or dissolved after processing, leaving no contamination.
Solution Approach 2:
The patent changes the physical parameters of the support structure from a solid, rigid tray to a structure with controlled porosity or solubility. The support structure may be made of a material that can be selectively removed or dissolved after processing, or designed with openings that allow access to both sides of the dies without flipping. This parameter change eliminates the harmful effects of conventional die trays while maintaining their functional benefits.
3Ease of operation
If dies are flipped during processing, then bottom side processing can be performed, but the flipping operation becomes a greater liability as die thicknesses decrease
Solution Approach 1:
The patent inverts the conventional approach by keeping the dies in their original orientation and providing access to the bottom side through the support structure rather than flipping the dies. This is particularly important for thin dies where flipping would cause damage. The support structure allows bottom side processing equipment to access the dies from below while the dies remain supported from above.
Solution Approach 2:
An intermediary support structure serves as a mediator between the processing equipment and the thin dies. This structure provides mechanical support to prevent damage during processing while allowing access to both top and bottom surfaces. The intermediary structure absorbs the mechanical stresses that would otherwise be applied directly to the thin dies during handling and processing.
4Ease of operation
If conventional flipping operations are used, then dies can be transferred between trays, but loose particles prevent intimate mating between the dies and the mating and bonding surfaces beneath
Solution Approach 1:
The patent removes the source of loose particles (conventional die trays and flipping operations) from the process. By using a support structure that does not require flipping and can be selectively removed or dissolved, the system eliminates the generation of loose particles that would contaminate bonding surfaces and prevent intimate mating between dies and substrates.
Solution Approach 2:
The support structure acts as an intermediary that enables die transfer without generating contamination. The structure is designed to be compatible with the bonding process, either being removable before bonding or soluble/evaporable without leaving residues. This ensures that no loose particles are introduced that would interfere with the intimate contact required for successful bonding.
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 eliminates the need for die flipping, reducing contamination and damage, allowing for high-yield, low-cost stacking of very thin dies without particulate debris, ensuring the integrity of bonding steps and accommodating various bonding techniques like DBI and ZIBOND.
Implementation Method 1
A liftoff apparatus directs a gas flow, such as filtered air, nitrogen, an inert gas, or a gas used chemically in an assembly step, to the bottom side of the dies for lifting the dies from the die tray
Data Source
AI summary
Methods and apparatuses for stacking devices in an integrated circuit assembly are provided. A tray for supporting multiple dies of a semiconductor material enables both top side processing and bottom side processing of the dies. The dies can be picked and placed for bonding on a substrate or on die stacks without flipping the dies, thereby avoiding particulate debris from the diced edges of the dies from interfering and contaminating the bonding process. In an implementation, a liftoff apparatus directs a pneumatic flow of gas to lift the dies from the tray for bonding to a substrate, and to previously bonded dies, without flipping the dies. An example system allows processing of both top and bottom surfaces of the dies in a single cycle in preparation for bonding, and then pneumatically lifts the dies up to a target substrate so that top sides of the dies bond to bottom sides of dies of the previous batch, in an efficient and flip-free assembly of die stacks.