Semiconductor Chip Dicing via Rear Surface Trenches and Laser Stealth Cutting
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Solution Overview
Problem
Existing methods for manufacturing semiconductor chips for liquid discharge heads, such as laser stealth dicing and trench formation, face challenges in productivity due to increased laser irradiation times and compromised design freedom, as well as surface treatment issues with dicing tape affecting water repellency.
Innovation Solution
A method involving forming linear trenches on the rear surface of the substrate, irradiating a laser beam from the front side along intended cutting portions to create modified regions, and splitting the substrate with applied stress, while maintaining cutting precision and design freedom by reducing laser irradiation and avoiding dicing tape on the channel forming member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple modified portions are formed in the thickness direction of the substrate to cut without compromising precision, then cutting precision is improved, but the number of laser beam irradiations increases resulting in low productivity
Solution Approach 1:
A trench is formed through etching before laser beam irradiation to preliminarily reduce the substrate thickness at the cutting portion. This preliminary action reduces the number of modified portions needed in the thickness direction, thereby reducing laser beam irradiations while maintaining cutting precision
Solution Approach 2:
The cutting process is segmented into two distinct steps: (1) forming a trench through etching to reduce local substrate thickness, and (2) forming modified portions through laser beam irradiation to enable precise cutting. This segmentation allows each step to optimize for its specific function, improving overall efficiency
2Productivity
If a trench is formed on the surface with the electrode to reduce substrate thickness and laser irradiation times, then productivity is improved, but the area for forming the trench must be secured reducing design freedom
Solution Approach 1:
Instead of forming the trench on the front surface (first surface) with the electrode as in conventional methods, the trench is formed on the rear surface (second surface) of the substrate. This inversion allows the trench to be formed without occupying area on the front surface, thereby preserving design freedom while maintaining productivity improvements
3Ease of manufacture
If a dicing tape is attached on the channel forming member to irradiate laser beam from rear surface, then cutting process is enabled, but the water repellency is degraded and adhesive remains on the surface
Solution Approach 1:
The laser beam irradiation is performed from the front surface (first surface) instead of the rear surface (second surface). This inversion eliminates the need to attach a dicing tape on the channel forming member, thereby preserving water repellency and preventing adhesive contamination while enabling the cutting process
Solution Approach 2:
The dicing tape attachment step is completely removed from the process by changing the laser irradiation direction. This extraction eliminates the harmful effects of adhesive contamination and water repellency degradation while maintaining the essential cutting function
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 cutting precision, reduces laser irradiation times, maintains water repellency, and increases productivity by forming trenches on the rear surface, ensuring high precision and design flexibility without degrading the channel forming member's surface.
Implementation Method 1
a laser beam is condensed and focused at a point in the substrate to metamorphose a property inside
Implementation Method 2
By this method, the thickness of the substrate is reduced at the portion to be cut
Implementation Method 3
the substrate is split using cracks formed from the modified portion as a starting point by applying external force to the substrate
Implementation Method 4
A trench is formed through etching in a surface provided with an electrode of a substrate
Data Source
AI summary
A method of manufacturing a plurality of semiconductor chips for a liquid discharge head from a substrate includes forming trenches of a linear form through etching from the second surface along intended cutting portions, forming modified portions in the substrate by irradiating a laser beam from the first surface side along the intended cutting portions, and splitting the substrate into the plurality of semiconductor chips for a liquid discharge head, by cutting the substrate with stress applied to the modified portions. The intended cutting portions include inclined portions extending in a direction inclined with respect to a crystal orientation plane of the substrate and uninclined portions extending in a direction along the crystal orientation plane of the substrate, and the trenches are formed at least along the inclined portions.