Receiving Substrate Pads for Hybrid Bonding Without UBM Plating
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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 to solder bonding, as they necessitate the formation of under bump metallization (UBM) pads on the receiving substrate.
Innovation Solution
A receiving substrate is designed with embedded contact pads in dielectric layers, allowing for hybrid and solder bonding without UBM pads, featuring a two-layer structure for solder pads that slows intermetallic compound formation and incorporates additional test pads for electrical testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hybrid bonding is applied first followed by solder bonding on the same receiving substrate, then both bonding techniques can be used on the substrate, but additional process steps such as plating UBM pads are required which complicates the process and may damage hybrid bonded dies
Solution Approach 1:
The receiving substrate is divided into distinct first landing areas configured for hybrid bonding and second landing areas configured for solder bonding. Contact pads in different landing areas have different configurations: hybrid bonding contact pads are embedded in dielectric layers with planarized surfaces, while solder bonding contact pads are exposed on the surface without requiring UBM pads. This spatial segmentation allows both bonding techniques to be applied on the same substrate without process conflicts or additional complex steps.
2Adaptability or versatility
If UBM pads are plated on the receiving substrate after hybrid bonding, then solder bonding can be performed, but this may lead to damaging of the hybrid bonded dies
Solution Approach 1:
Solder bonding contact pads are pre-configured on the receiving substrate in second landing areas before any bonding operations. These contact pads are designed to receive solder material directly without requiring subsequent UBM pad plating. This preliminary configuration eliminates the need for post-hybrid-bonding plating processes that could damage the hybrid bonded dies, while still enabling solder bonding to be performed afterward.
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, protecting hybrid dies and facilitating efficient electrical testing, while ensuring robust connections.
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/or 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 the invention, additional contact pads (71) are incorporated in a stack of dielectric material into which the hybrid and/or 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 bonding of further dies.