Chip Bonding Head for Thin Direct-Bonded Stacks
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Solution Overview
Problem
Existing chip-to-wafer and chip-to-chip bonding methods using solder balls or copper pillars result in thick chip stacks and inefficiencies due to the need for additional materials and increased thickness, which hampers bond strength and communication efficiency.
Innovation Solution
A direct bonding method and device that eliminates the need for solder balls or copper pillars by using a contamination-free surface cleaning and self-alignment process to achieve a strong, hybrid metal-metal bond at low temperatures without a liquid phase, enhancing bond strength and reducing chip stack thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder balls or copper pillars with solder caps are used for chip bonding, then chip-to-wafer or chip-to-chip bonding can be achieved, but the chip stack thickness increases significantly
Solution Approach 1:
The invention extracts and eliminates the intermediate bonding materials (solder balls, copper pillars, solder caps) from the bonding process. By directly bonding chip surfaces together without these additional components, the chip stack thickness is significantly reduced while maintaining bond strength through direct metal-to-metal contact and diffusion bonding mechanisms.
Solution Approach 2:
The invention merges the chip surfaces directly with each other, eliminating the need for separate bonding materials. The bond interface is formed by direct contact between the chip surfaces themselves, combining the functional elements into a more integrated and compact structure that reduces overall thickness.
2Reliability
If solder balls or copper pillars with solder caps are used for chip bonding, then bonding can be achieved, but the number of additional materials and process steps increases
Solution Approach 1:
The invention removes the complex intermediate structures (solder balls, copper pillars, solder caps) and their associated deposition, formation, and bonding processes. This extraction simplifies the overall bonding device and process while achieving reliable bonds through direct surface interaction.
Solution Approach 2:
Instead of building up complex intermediate structures to achieve bonding, the invention inverts the approach by directly bonding the chip surfaces together. This reversal of the conventional approach eliminates multiple process steps and reduces device complexity while maintaining or improving bond strength.
3Length of stationary object
If direct bonding is used to reduce chip stack thickness, then thickness is reduced, but surface contamination must be严格控制 to achieve strong bonds
Solution Approach 1:
The invention implements preliminary surface cleaning and preparation steps before the direct bonding process. By pre-cleaning the chip surfaces to remove contaminants and pre-heating or pre-treating the surfaces, the bonding process becomes more tolerant to minor contamination variations, making the manufacturing process more controllable despite the high cleanliness requirements.
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
The direct bonding method increases chip communication efficiency, reduces chip stack thickness, and achieves bond strengths greater than 0.1 J/m2, while operating at temperatures below 400°C, thereby improving the overall efficiency and performance of chip bonding processes.
Implementation Method 1
the bond surface of which is to be cleaned is cleaned by means of a plasma cleaning process
Implementation Method 2
The direct bond in particular occurs at temperatures of less than 400° C., preferably less than 300° C., more preferably at less than 2000° C., most preferably less than 150° C., most preferably of all less than 100° C.
Implementation Method 3
A direct bond is in particular understood to be a metal-metal solid body bond, in particular diffusion bond
Data Source
AI summary
A method and device for bonding chips onto a substrate or onto further chips. The chips are bonded onto the substrate or the further chips by means of a direct bond using a bond head having a first surface configured to couple to a chip that is to be bonded, and a second surface fixed to and disposed opposite the first surface. A first spring element having a first spring constant and a second spring element having a second spring constant are coupled to the second surface, where the first spring constant is different from the second spring constant.