Direct Chip Bonding Without Solder Balls or Copper Pillars
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Solution Overview
Problem
Current chip bonding processes using solder balls or copper pillars result in increased chip thickness and require additional materials, which can lead to contamination and reduced throughput.
Innovation Solution
A direct bonding method that eliminates the need for solder balls or copper pillars, utilizing a clean bonding surface and self-alignment techniques to achieve a metal-to-metal solid-state bond, preferably at temperatures below 400°C, without forming a liquid phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder balls or copper pillars with solder caps are used for chip bonding, then reliable electrical connection is achieved, but chip thickness increases and additional materials are required
Solution Approach 1:
The invention extracts and eliminates the intermediate bonding elements (solder balls, copper pillars, solder caps) from the chip bonding process. By directly bonding chip surfaces together without these additional components, the patent achieves reliable electrical connection while significantly reducing chip stack thickness.
Solution Approach 2:
The invention merges the bonding function directly into the chip surfaces themselves by creating metal-to-metal solid-state bonds between opposing chip surfaces. This eliminates the need for separate bonding elements and integrates the connection function directly into the chip structure.
2Reliability
If solder balls or copper pillars with solder caps are used for chip bonding, then electrical connection is established, but the number of additional materials and process steps increases
Solution Approach 1:
The invention removes multiple intermediate materials (solder balls, copper pillars, solder caps) and their associated deposition, placement, and reflow processes from the manufacturing sequence. This extraction simplifies the overall device structure and reduces process complexity while maintaining electrical connection reliability.
Solution Approach 2:
The invention combines multiple functions (electrical connection, mechanical bonding, and thermal management) directly into the chip surface interface through solid-state bonding, eliminating the need for separate bonding elements and their associated complex manufacturing processes.
3Reliability
If traditional chip bonding processes are used, then chips can be connected, but throughput is reduced due to additional process steps
Solution Approach 1:
The invention extracts and eliminates multiple sequential process steps (solder ball placement, copper pillar deposition, solder cap formation, reflow processing) from the manufacturing flow. By removing these intermediate steps and implementing direct solid-state bonding, the process throughput is significantly increased while maintaining reliable chip connections.
4Reliability
If additional bonding materials are used, then bonding is facilitated, but contamination risk increases
Solution Approach 1:
The invention extracts and eliminates additional bonding materials (solder, copper pillars, fluxes) from the process. By bonding chip surfaces directly to each other without intermediate materials, the risk of contamination from these substances is removed, while bonding reliability is maintained through direct metal-to-metal solid-state 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
Reduces chip stack thickness, increases throughput, and enhances chip communication performance with bond strengths exceeding 0.1 J/m², while maintaining a contamination-free bonding process.
Implementation Method 1
A direct bond is understood to be a bond that forms directly through the interaction of two surfaces without forming a liquid phase. According to another definition, a direct bond is understood to be a bond in which no additional materials are required. In particular, a direct bond is understood to be a metal-to-metal solid-state bond, especially a diffusion bond
Implementation Method 2
The invention is based on the idea of keeping the surface of a chip so clean that a subsequent direct bonding step can take place
Data Source
Figure 1a~1g
Figure 2a~2e
Figure 2f~4
AI summary
A method for bonding chips (7) to a substrate (11') or to further chips is proposed, characterized in that the chips (7) are bonded to the substrate (11') or the further chips by direct bonding.