Laser-Assisted Bonding Mask for Semiconductor Wafer Warpage
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Solution Overview
Problem
The semiconductor industry faces challenges in achieving high integration density and reducing wafer warpage while maintaining manufacturing throughput, particularly in Package-on-Package (PoP) technology, where traditional bonding methods are inefficient and may cause warpage and slow down the manufacturing process.
Innovation Solution
The implementation of a laser-assisted bonding (LAB) process using a multi-layer masking apparatus that selectively heats specific areas of semiconductor package components, allowing for precise bonding of package components with reduced warpage and increased throughput by configuring different laser beam profiles and positions of the masking apparatus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional bonding methods are used, then manufacturing throughput is maintained, but wafer warpage increases and bonding efficiency decreases
Solution Approach 1:
The patent replaces traditional mechanical heating methods with laser-based heating. The laser beam directly heats the bonding interface between wafers, enabling precise thermal control without the mechanical contact and thermal mass associated with conventional heating systems. This substitution allows for rapid, localized heating that reduces wafer warpage while maintaining high manufacturing throughput.
Solution Approach 2:
The patent applies heating locally at the bonding interface rather than uniformly across the entire wafer. The laser beam is focused on specific regions where bonding is required, creating localized thermal zones that minimize thermal stress and warpage while enabling selective bonding of different areas at different times. This local quality approach directly addresses the warpage issue while maintaining productivity.
2Productivity
If laser heating is applied to entire wafer surface, then bonding speed increases, but thermal stress and warpage increase
Solution Approach 1:
The patent uses a masking layer with patterned openings to restrict laser heating to specific local regions rather than the entire wafer surface. The masking layer is positioned between the laser source and the wafer, allowing the laser beam to pass through openings and heat only the intended bonding areas. This selective local heating maintains high bonding speed while minimizing thermal stress and warpage by avoiding unnecessary heating of large wafer areas.
Solution Approach 2:
The patent divides the wafer surface into multiple regions using the masking layer, which contains multiple discrete openings. Each opening corresponds to a specific bonding region, allowing independent control and heating of different areas. This segmentation enables the process to heat multiple locations sequentially or in parallel, maintaining high throughput while limiting thermal stress to only the necessary localized areas.
3Manufacturing precision
If masking layer with multiple openings is used, then selective heating precision increases, but device complexity increases
Solution Approach 1:
The patent creates a physical mask that is a simplified copy or representation of the desired heating pattern. Rather than using complex robotic positioning systems or dynamic beam shaping, the masking layer is a static component with pre-formed openings that directly replicate the bonding pattern. This copying approach achieves high heating precision through a relatively simple and inexpensive masking structure, avoiding the need for complex active control systems.
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 effectively reduces wafer warpage and enhances manufacturing efficiency by allowing for faster and more precise bonding of semiconductor components, improving the integration density and consistency of package structures without causing significant thermal stress.
Implementation Method 1
a laser beam generator to generate a laser beam... The LAB process allows the first and second package components to be bonded together by directly heating only the top package component
Implementation Method 2
The masking apparatus is used to restrict the laser beam to heating particular package regions by allowing laser shots to pass through openings in the masking layer and hit target package regions
Implementation Method 3
a first package component is bonded to a second package component by a laser assisted bonding (LAB) process... performing a first laser shot, the laser passing through a first gap in the masking layer and passing through the transparent layer to heat a first portion of a top side of the die opposite the substrate
Data Source
AI summary
A method for bonding semiconductor substrates includes placing a die on a substrate and performing a heating process on the die and the substrate to bond the respective first connectors with the respective second connectors. Respective first connectors of a plurality of first connectors on the die contact respective second connectors of a plurality of second connectors on the substrate. The heating process includes placing a mask between a laser generator and the substrate and performing a laser shot. The mask includes a masking layer and a transparent layer. Portions of the masking layer are opaque. The laser passes through a first gap in the masking layer and through the transparent layer to heat a first portion of a top side of the die opposite the substrate.