Preformed Metal Support Substrates for Warp-Resistant SSL Wafers
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Solution Overview
Problem
Conventional SSL devices face issues with warping and deformation during thermo-compression bonding on large-diameter wafers, limiting throughput and increasing costs due to the need for high temperatures and pressures, which are not feasible for substrates larger than 4 inches.
Innovation Solution
The use of a preformed metal support substrate bonded to the light emitting structure using metal-metal bonds or intermetallic compound (IMC) bonding, which provides structural support and inhibits bowing, allowing for larger wafer diameters without cracking or warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional support substrates (sapphire or semiconductor) are used with thermo-compression bonding, then bonding strength is achieved, but wafer warping and deformation occur at high temperatures and pressures
Solution Approach 1:
The patent changes the material parameter of the support substrate from conventional sapphire or semiconductor materials to metal materials (such as copper, aluminum, or their alloys). This material substitution enables the substrate to better withstand high temperature and pressure during bonding while maintaining dimensional stability, thus resolving the contradiction between achieving strong bonding and preventing wafer deformation.
2Productivity
If large-diameter wafers (>4 inches) are used, then manufacturing throughput increases, but wafer bowing and cracking become severe
Solution Approach 1:
The patent changes the material composition of the support substrate to metal materials with superior mechanical properties including higher elastic modulus and thermal conductivity. These parameter changes enable large-diameter wafers to maintain structural integrity during high-temperature processing while allowing increased manufacturing throughput through larger wafer sizes.
Solution Approach 2:
The metal support substrate acts as an intermediary between the light-emitting structure and the final packaging substrate. It provides mechanical support and thermal management during the bonding process, enabling large-diameter wafers to be processed without direct contact between the fragile light-emitting structure and the high-temperature bonding environment.
3Strength
If high temperatures and pressures are applied for bonding, then strong bonding is achieved, but wafer cracking and warping increase
Solution Approach 1:
The patent changes the thermal and mechanical parameters of the support substrate by using metal materials with higher thermal conductivity and elastic modulus. This allows the substrate to dissipate heat more efficiently and resist thermal stress during bonding, maintaining dimensional control even under high temperature and pressure conditions required for strong 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
The preformed metal substrate enhances the rigidity and conductivity of SSL devices, enabling cost-effective production of larger diameter wafers with reduced bowing, thus improving manufacturing efficiency and reducing production costs.
Implementation Method 1
The use of a preformed metal support substrate bonded to the light emitting structure using metal-metal bonds or intermetallic compound (IMC) bonding
Implementation Method 2
SSL devices generally use semiconductor light emitting diodes (LEDs) and/or polymer light emitting diodes (PLEDs) as sources of illumination
Implementation Method 3
As a voltage is applied between the n-type contact 22 and the p-type contact 20, electrical current passes through the light emitting structure 17 and produces light
Implementation Method 4
The preformed metal substrate enhances the rigidity and conductivity of SSL devices
Data Source
AI summary
A wafer-level process for manufacturing solid state lighting (“SSL”) devices using large-diameter preformed metal substrates is disclosed. A light emitting structure is formed on a growth substrate, and a preformed metal substrate is bonded to the light emitting structure opposite the growth substrate. The preformed metal substrate can be bonded to the light emitting structure via a metal-metal bond, such as a copper-copper bond, or with an inter-metallic compound bond.