Receiving Substrate Layout for Hybrid and Direct Solder Bonding
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Solution Overview
Problem
Existing semiconductor bonding methods require complex process steps and risk damage to hybrid bonded dies when transitioning from hybrid bonding to solder bonding, as they necessitate the formation of under bump metallization (UBM) pads on the receiving substrate.
Innovation Solution
A receiving substrate is prepared with hybrid and solder landing areas containing contact pads embedded in dielectric layers, allowing direct solder bonding without UBM pads, using a two-layer contact pad structure with a slower intermetallic compound formation bottom layer to protect underlying connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If UBM pads are formed on the receiving substrate after hybrid bonding, then solder bonding can be performed, but the hybrid bonded dies may be damaged and the process becomes complex
Solution Approach 1:
The receiving substrate is divided into distinct first landing areas for hybrid bonding and second landing areas for solder bonding. Contact pads in hybrid bonding areas are configured for direct dielectric-to-dielectric and metal-to-metal bonding, while contact pads in solder bonding areas are designed to receive solder bumps directly without requiring UBM pad formation. This segmentation allows both bonding techniques to be performed on the same substrate without process conflicts.
Solution Approach 2:
Different landing areas on the receiving substrate are given different local properties: hybrid bonding landing areas have contact pads suitable for direct hybrid bonding, while solder bonding landing areas have contact pads specifically designed to accept solder bumps. This local differentiation eliminates the need for post-hybrid-bonding UBM pad formation and prevents damage to hybrid bonded dies.
2Adaptability or versatility
If UBM pads are plated after hybrid bonding, then solder bonding is enabled, but the risk of damaging hybrid bonded dies increases
Solution Approach 1:
The receiving substrate is pre-configured with distinct contact pad structures in different landing areas before any bonding occurs. Solder bonding landing areas are prepared with contact pads that can directly receive solder bumps, eliminating the need for post-hybrid-bonding UBM pad plating and thereby preventing damage to previously bonded hybrid dies.
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
Enables seamless transition between hybrid and solder bonding without additional process steps, reducing the risk of damage to hybrid bonded dies and simplifying the bonding process.
Implementation Method 1
the bottom layer being formed of a material exhibiting slower intermetallic compound formation when reacting with solder than the material of the top layer
Implementation Method 2
The bonding involves realizing a direct dielectric-to-dielectric bond between the dielectric bonding surfaces and a direct metal-to-metal bond between aligned contact pads on the two surfaces, under the influence of an annealing temperature and possibly a mechanical pressure
Data Source
Figure 1a~2b
Figure 3a~6b
Figure 7a~11
AI summary
A receiving substrate (1) is produced, configured to receive thereon one or more dies (3) by hybrid bonding in one or more first landing areas (2a) and a one or more dies (4) by solder bonding in a one or more second landing areas (2b). In the two types of landing areas, contact pads (29,35,36) are formed which are embedded in a dielectric layer (37,50) or a stack of dielectric layers (27,28), enabling hybrid bonding in the hybrid bonding landing areas. The contact pads in the solder landing areas are configured to receive solder material directly on said contact pads after bonding of the hybrid bonded dies, without requiring the formation of under bump metal pads. According to preferred embodiments, at least the solder contact pads comprise two layers (29a,29b), a bottom layer and a top layer, the bottom layer being formed of a material exhibiting slower intermetallic compound formation when reacting with solder than the material of the top layer. According to further embodiments, additional contact pads (71) are incorporated in a stack of dielectric material into which the hybrid and solder contact pads are embedded, in a manner that enables to reveal said additional contact pads (71) after hybrid and solder bonding. Said additional contact pads may be configured for electrical testing of bonded dies or dies within the receiving substrate, or for wire bonding of further dies.