Buried Laser Marking in Semiconductor Substrates
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Solution Overview
Problem
Current laser marking techniques for semiconductor devices face limitations in flexibility and application scope, particularly in preserving alignment accuracy and hiding markings during substrate thinning processes.
Innovation Solution
The method involves forming a laser marking buried within the semiconductor substrate, allowing for precise alignment and hiding the marking until needed, either by exposing it at the backside surface or keeping it concealed for infrared visualization, using infrared lasers focused at specific depths to create markings that can be preserved during thinning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If laser marking is performed on the semiconductor substrate surface, then marking visibility is achieved, but recast material is generated causing surface defects
Solution Approach 1:
The laser marking is formed within the semiconductor substrate before the substrate thinning process. This preliminary action allows the marking to be created in a position that will later be exposed at the backside surface, avoiding the need to mark on the final thin surface where recast material would be problematic.
Solution Approach 2:
The marking is transitioned from a surface-level feature to a subsurface feature by forming it at a specific depth within the substrate. This dimensional change allows the marking to be created in the bulk material where recast material does not affect surface quality, and then exposed through subsequent thinning.
2Loss of information
If substrate thinning is performed to expose the marking, then marking visibility is achieved, but alignment accuracy may be compromised
Solution Approach 1:
The laser marking is formed at a predetermined depth within the substrate before thinning occurs. This preliminary positioning ensures that when the substrate is subsequently thinned to the target thickness, the marking is automatically exposed at the correct location on the backside surface, maintaining alignment accuracy without requiring additional post-thinning adjustment steps.
3Manufacturing precision
If laser marking is performed after substrate thinning, then marking precision is improved, but flexibility and applicability are reduced
Solution Approach 1:
The laser marking is formed in advance during the substrate processing sequence, allowing the marking parameters (depth, position, characteristics) to be optimized independently of the final substrate thickness. This preliminary formation provides flexibility in adjusting marking properties without being constrained by the thinning process, while still achieving high precision through controlled exposure at the backside surface.
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 enhances the flexibility and applicability of laser marking by maintaining marking accuracy and visibility as needed, avoiding recast material issues and enabling precise identification and orientation during assembly and packaging.
Implementation Method 1
forming at least one laser marking buried within a semiconductor substrate
Implementation Method 2
using infrared lasers focused at specific depths to create markings
Data Source
AI summary
A method for forming a semiconductor device includes forming a laser marking buried within a semiconductor substrate and thinning the semiconductor substrate from a backside of the semiconductor substrate. For example, a semiconductor device includes a semiconductor substrate located in a semiconductor package. A laser marking is buried within the semiconductor substrate. For example, another semiconductor device includes a semiconductor substrate. A laser marking is located at a backside surface of the semiconductor substrate. Further, a portion of the backside surface located adjacent to the laser marking is free of recast material.