Radiant Substrate Heating for Low-Stress Thermocompression Bonding

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Solution Overview

Problem

Thermocompressive bonding processes for semiconductor packaging can cause induced thermal damage and thermal cycling, leading to reliability issues and performance degradation due to elevated temperatures and mechanical stress on semiconductor devices.

Innovation Solution

A radiant heating method is used in conjunction with a transparent substrate to heat the packaging substrate, maintaining a higher temperature than the semiconductor die, reducing thermal cycling and ensuring uniform reflow of solder material portions, thereby minimizing thermal damage and enhancing bonding reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If heat is applied to the semiconductor die during thermocompressive bonding, then the bonding process can be completed, but thermal damage occurs to the semiconductor materials

Engineering Contradiction:

Improvebonding reliabilityVSAvoidthermal damage to semiconductor

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A transparent substrate is introduced as an intermediary between the heat source and the semiconductor die. The substrate transmits radiant heat to the solder material while protecting the semiconductor die from direct thermal exposure, thereby enabling bonding without damaging the sensitive semiconductor components

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

Heat is applied selectively to specific regions rather than uniformly to the entire assembly. The radiant heating system targets the solder material portions and substrate interface locally, maintaining lower temperatures at the semiconductor die while achieving sufficient heat for bonding at the interface regions

Inventive Principle:

Principle #3Local quality

2Reliability

If repeated heating and cooling cycles are applied during bonding, then the bonding process can proceed, but thermal cycling induces mechanical stress and degrades device performance

Engineering Contradiction:

Improvebonding process completionVSAvoiddevice performance stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The substrate is pre-heated to the required bonding temperature before the semiconductor die is introduced. This preliminary heating action ensures that when the die is placed on the substrate, minimal thermal cycling is required to achieve bonding conditions, thereby reducing mechanical stress on the devices

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The transparent substrate acts as a thermal buffer that mediates between the heat source and the semiconductor devices. It allows controlled heat transmission to achieve bonding while dampening rapid temperature changes that would cause severe thermal cycling and mechanical stress

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If high temperature is applied to ensure solder reflow, then bonding can be achieved, but non-uniform heating causes thermal damage

Engineering Contradiction:

Improvesolder reflow qualityVSAvoidtemperature uniformity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The transparent substrate serves as a heat distribution intermediary that receives radiant energy and distributes it uniformly across the bonding interface. This intermediary layer ensures even heat propagation to the solder material portions, achieving uniform reflow without creating hot spots that would damage the semiconductor

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The heating method uses radiant energy with specific wavelength parameters that are optimized for uniform transmission through the substrate and absorption by the solder material. By controlling the radiation parameters, uniform heating is achieved across the entire bonding interface while maintaining precise temperature control

Inventive Principle:

Principle #35Parameter changes

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 approach reduces thermal cycling on semiconductor dies, minimizes thermal degradation, and achieves more uniform bonding structures, improving the reliability and performance of semiconductor devices.

Implementation Method 1

heating a top surface of the plate (600) to a second temperature (T2) using radiative heating

Methodology Applied

Scientific EffectRadiative heating: Thermal Radiation

Implementation Method 2

bonding the semiconductor die (800) to the packaging substrate (200) by reflowing and solidifying the array of solder material portions (290)

Methodology Applied

Scientific EffectReflow: Melting

Data Source

PatentUS20240371816A1Radiant substrate heating for thermocompressive bonding and apparatus for implementing the same

Publication Date: 2024.11.07 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A bonded assembly may be formed by: disposing a packaging substrate having substrate-side bonding structures over a transparent plate; heating the packaging substrate using radiative heating in which a radiative heating source provides radiation to a bottom surface of the packaging substrate through the transparent plate; attaching a semiconductor die having die-side bonding structures to a bottom of a thermocompressive bonding head; bringing the semiconductor die and the packaging substrate to indirect contact with each other with an array of solder material portions therebetween; and bonding the semiconductor die to the packaging substrate by reflowing and solidifying the solder material portions.