Semiconductor Dicing via Laser Amorphization and Photolithography
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Solution Overview
Problem
Current dicing techniques for semiconductor devices, such as saw dicing and laser ablation, are inadequate for substrates with thick or highly doped semiconductor layers, as they fail to produce controlled dicing lanes up to the edges of the substrate, leading to uncontrolled fracture lines and potential device failure during separation.
Innovation Solution
A method involving step-by-step photolithography using a reticle to define first dicing lanes and a conventional photolithography system to define second dicing lanes, followed by laser irradiation to form controlled lines of weakness, ensuring controlled separation of semiconductor devices regardless of substrate thickness or doping level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If saw dicing is used to cut substrates, then dicing lines can be produced quickly through the entire substrate, but high-pressure water jets are required for cooling and residue removal, causing breaking and sticking of mobile device elements
Solution Approach 1:
The patent replaces the mechanical saw dicing system with a laser-based system. The laser beam locally modifies the crystalline structure of the semiconductor substrate through photomodification, creating amorphous regions that serve as stress concentration points. This substitution eliminates the need for mechanical contact and high-pressure water jets, thereby preventing device breaking and sticking while maintaining dicing capability.
Solution Approach 2:
The patent changes the physical state of the semiconductor material through laser irradiation. The laser beam transforms the crystalline structure of the semiconductor into an amorphous state at the focal point, creating lines of weakness. This parameter change (crystalline to amorphous transition) allows for controlled fracture without mechanical force or water jets, resolving the contradiction between dicing efficiency and device integrity.
2Ease of operation
If laser ablation dicing is used, then cooling means are not required and dicing patterns other than straight lines can be produced, but particles generated by laser dicing are redeposited on the diced substrate, causing contamination
Solution Approach 1:
The patent modifies the laser processing parameters to change the interaction mechanism between the laser beam and substrate. Instead of ablation that generates redeposited particles, the laser parameters are optimized to locally amorphize the crystalline semiconductor structure. This parameter change eliminates particle generation while maintaining the flexibility to create various dicing patterns including curved and non-straight lines.
Solution Approach 2:
The patent converts the potential harm of laser-induced material modification into a beneficial effect. By controlling the laser parameters, the crystalline-to-amorphous transformation creates controlled lines of weakness that guide fracture along desired paths. This converts what could be harmful (uncontrolled melting or ablation) into a useful mechanism for precise, contamination-free dicing with pattern flexibility.
3Reliability
If photolithography pattern is not extended to substrate edges, then device production is safe from edge-related defects, but dicing lanes cannot be produced up to the edges of the substrate, leading to uncontrolled fracture lines during separation
Solution Approach 1:
The patent applies preliminary action by creating photomodified lines of weakness through laser irradiation before the actual device separation process. These pre-created lines of weakness are positioned exactly where dicing lanes are needed, including up to the substrate edges. This preliminary modification ensures that when separation occurs, fracture follows the predetermined paths rather than creating uncontrolled lines, thus maintaining both reliability and precision.
Solution Approach 2:
The patent introduces an intermediary mechanism - the photomodified amorphous lines - that mediates between the need for edge-proximity dicing and the risk of uncontrolled fracture. These laser-created lines serve as controlled weak points that guide the fracture process, allowing dicing lanes to extend to substrate edges without compromising device safety or fracture control.
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 method allows for controlled separation of semiconductor devices without uncontrolled fracture lines, even in thick or highly doped substrates, eliminating the risks associated with existing dicing techniques and ensuring the integrity of the devices during separation.
Implementation Method 1
a laser beam is used to locally modify, at the focal point of the beam, the crystalline structure of the semiconductor of the substrate to be diced. Since the illuminated semiconductor becomes locally amorphous in a crystalline environment, a stress concentration appears at this location and relaxes by microcracking.
Data Source
AI summary
Process for producing semiconductor devices in a substrate, comprising: photolithography of a pattern of a reticle onto a portion of the substrate, defining first elements of the semiconductor devices, an exposure of the pattern being repeated a plurality of times in order to define all of the devices, photolithography of a pattern of an etch mask over all of the substrate, etching photolithography patterns into one portion of the thickness of the substrate, wherein first dicing lanes encircling the devices are included in the pattern of the etch mask and/or of the reticle, and the photolithography of the etch mask defines second dicing lanes defined by predetermined fracture lines of the edges of the substrate, and furthermore comprising the implementation of a step of irradiating the substrate with a laser beam through the first and second dicing lanes.