TSV Die Assembly via Face-Down Adhesive Bonding
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Solution Overview
Problem
Conventional thermo-compression bonding methods for stacked die assemblies with TSV dies often damage TSV tips, pillars, and low-k dielectric layers due to high pressure and heat, leading to reduced yield and reliability issues.
Innovation Solution
The process involves positioning TSV dies with protruding features face-down on a curable adhesive layer, allowing for low-pressure pick and place without heating, followed by partial curing and chip stacking, using a modified TC bonding process at reduced pressure and temperature, and subsequent debonding and singulation to form stacked die assemblies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional thermo-compression bonding is used to attach TSV die, then bonding strength is achieved, but TSV tips, pillars, and low-k dielectric layers are damaged due to high pressure and heat
Solution Approach 1:
The bonding process is segmented into two distinct stages: first, attaching the TSV die to a carrier substrate using low-pressure pick-and-place bonding; second, attaching the TSV die to the target substrate using conventional thermo-compression bonding. This segmentation allows the delicate TSV die to be positioned without direct exposure to high bonding pressures, while the carrier substrate absorbs the mechanical stress.
Solution Approach 2:
A carrier substrate is introduced as an intermediary element in the bonding process. The TSV die is first bonded to the carrier substrate, which serves as a protective platform during positioning. The carrier substrate acts as a mediator that shields the TSV die from direct mechanical stress during the bonding process, enabling subsequent attachment to the target substrate without damage.
2Reliability
If high compressive force is applied during TC bonding, then bonding reliability is improved, but yield is reduced due to damage to bonding features and surrounding layers
Solution Approach 1:
The bonding process is divided into two stages: initial low-pressure attachment to a carrier substrate, followed by final high-reliability bonding to the target substrate. This segmentation enables the TSV die to be positioned and secured with minimal stress, preserving bonding features and surrounding layers, while still achieving reliable final bonding through the second stage.
Solution Approach 2:
The carrier substrate provides beforehand cushioning by absorbing and distributing the mechanical stress during the bonding process. This protective platform prevents direct transmission of high compressive forces to the TSV die, thereby protecting bonding features and low-k dielectric layers from damage while maintaining bonding reliability.
3Ease of operation
If TSV die are positioned face-up for bonding, then bonding features are accessible, but TSV tips and surrounding layers are exposed to damaging forces
Solution Approach 1:
Instead of positioning the TSV die face-up for bonding as in conventional processes, the invention inverts the approach by positioning the TSV die face-down on the carrier substrate. This inversion protects the bonding features on the front side from direct exposure to bonding forces, while the bonding occurs through the carrier substrate interface.
Solution Approach 2:
The carrier substrate serves as an intermediary platform that enables bonding feature accessibility while protecting the TSV die from damage. The TSV die is positioned face-down on the carrier, allowing bonding features to be accessible for connection to the target substrate, while the carrier substrate shields the TSV tips and surrounding low-k dielectric layers from damaging forces during the bonding process.
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 method minimizes damage to TSV tips and low-k dielectric layers, enhancing yield and reliability by using a compliant adhesive layer for gentle placement and reduced thermal stress, enabling the formation of high-quality stacked die assemblies.
Implementation Method 1
positioning a plurality of TSV dies with their topside facing down onto a curable bonding adhesive layer on a carrier... The soft adhesive bonding layer allows use of low pressure positioning
Implementation Method 2
followed by at least partially curing the curable adhesive
Data Source
AI summary
A method of through substrate via (TSV) die assembly includes positioning a plurality of TSV die with their topside facing down onto a curable bonding adhesive layer on a carrier. The plurality of TSV die include contactable TSVs that include or are coupled to bondable bottomside features protruding from its bottomside. The curable bonding adhesive layer is cured after the positioning. A plurality of second IC die each having a plurality of second bonding features are bonded onto the plurality of TSV die to form a plurality of stacked die assemblies on the carrier. Debonding after the bonding separates the carrier from the plurality of stacked die assemblies. The plurality of stacked die assemblies are then singulated to form a plurality of singulated stacked die assemblies.