Laser Die Bonding with Spatial Beam Shaping for Uniform Heating
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Solution Overview
Problem
Existing methods for laser bonding semiconductor die to a substrate often result in connection or device failures due to uneven heating and warping of the semiconductor die, leading to unreliable mechanical and electrical connections.
Innovation Solution
A laser assisted bonding system that controls laser irradiation spatially and temporally by using a beam filter to adjust laser intensity based on heat path density, and a spot size changer to vary beam size during the bonding process, ensuring uniform heating and reducing warping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional laser bonding is used to bond semiconductor die to substrate, then bonding speed is improved, but uniformity of heating is deteriorated causing warping and connection failures
Solution Approach 1:
The patent applies local quality by using a beam filter with spatially varying optical properties to modulate laser beam intensity across different regions of the semiconductor die. The beam filter creates a non-uniform intensity distribution that compensates for the non-uniform thermal conductivity and heat capacity of the die, achieving uniform heating without warping while maintaining fast bonding speeds.
Solution Approach 2:
The patent changes the spatial distribution parameter of laser beam intensity by introducing a beam filter with specific optical transmission characteristics. This parameter change transforms the conventional uniform or Gaussian intensity profile into a customized profile that matches the thermal requirements of the semiconductor die, resolving the contradiction between speed and uniformity.
2Productivity
If high intensity laser beam is used for fast bonding, then bonding speed is improved, but warping and tilting of semiconductor die are exacerbated
Solution Approach 1:
The beam filter creates locally optimized intensity distribution where higher intensity is applied to regions requiring more heat and lower intensity to regions that heat quickly, preventing thermal runaway and warping while maintaining overall fast bonding speed.
Solution Approach 2:
The beam filter pre-compensates for potential warping by applying differential intensity before the bonding process completes, counteracting thermal gradients that would otherwise cause tilting and warping of the semiconductor die.
3Ease of operation
If uniform laser intensity is applied across the semiconductor die, then ease of operation is improved, but bonding quality is deteriorated due to non-uniform thermal response
Solution Approach 1:
The beam filter serves as an intermediary component between the laser source and the semiconductor die, translating simple uniform laser output into a complex spatially-modulated intensity profile that matches the thermal requirements of the die, thereby maintaining ease of operation while improving bonding quality.
Solution Approach 2:
The beam filter modifies the spatial distribution parameter of laser intensity to create a non-uniform profile that compensates for the non-uniform thermal properties of the semiconductor die, achieving reliable bonding without complicating the operation of the laser system itself.
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 system enhances bonding reliability by preventing die tipping and warping, improving mechanical and electrical connections between the semiconductor die and substrate, resulting in higher device quality and manufacturability.
Implementation Method 1
a beam homogenizer to convert Gaussian laser beams into flat-top beams
Implementation Method 2
laser assisted bonding of semiconductor die
Implementation Method 3
enhance or control laser irradiation of a semiconductor die
Data Source
AI summary
A system and method for laser assisted bonding of semiconductor die. As non-limiting examples, various aspects of this disclosure provide systems and methods that enhance or control laser irradiation of a semiconductor die, for example spatially and/or temporally, to improve bonding of the semiconductor die to a substrate.