Semiconductor Die Sidewall Smoothing to Prevent Adhesive Climb
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Solution Overview
Problem
Laser dicing in semiconductor manufacturing results in molten material on side surfaces, causing adhesive to climb onto the device upper surface, leading to contamination of electrode pads and electrical shorts, while blade dicing limits productivity due to slow blade moving speed and wide dicing street requirements.
Innovation Solution
A method that combines laser dicing with a subsequent blade removal step to smooth the side surfaces, reducing surface roughness and preventing adhesive climb, and uses high-speed laser dicing for initial cutting to enhance productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser dicing is used to cut wafers, then productivity is improved and dicing street width is reduced, but molten material is formed on side surfaces causing adhesive to climb up and contaminate electrode pads
Solution Approach 1:
The patent applies preliminary action by forming a protective coating on the device side surfaces before the adhesive bonding process. This coating is applied in advance to prevent the harmful effect of adhesive climbing up the molten material, thereby resolving the contradiction between using laser dicing for high productivity and preventing adhesive contamination.
2Manufacturing precision
If blade dicing is used to fully cut the wafer, then cutting completeness is achieved, but blade moving speed must be slow reducing productivity
Solution Approach 1:
The patent applies segmentation by dividing the dicing process into two stages: first using laser dicing to create initial cuts and separate most of the wafer, then using blade dicing only for final completion of cuts where needed. This segmented approach allows the blade to move faster since it doesn't need to cut the entire wafer thickness, thereby resolving the contradiction between cut completeness and productivity.
Solution Approach 2:
The patent extracts the majority of the cutting task from the blade dicing process and assigns it to laser dicing. The blade is then used only for the remaining portion of the cut, which reduces the blade's workload and allows for higher moving speeds while still achieving complete separation, thus resolving the productivity-precision contradiction.
3Manufacturing precision
If wider dicing street is used for blade dicing, then complete cutting is ensured, but device density is reduced
Solution Approach 1:
The patent segments the cutting function between laser and blade, allowing the use of narrower dicing streets since the laser creates precise initial cuts. This enables closer spacing of devices while still ensuring complete separation, thereby resolving the contradiction between cut completeness and device density.
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
Prevents adhesive climb while improving productivity by reducing surface roughness and allowing for faster processing and increased device density, enabling the use of various adhesives and materials.
Implementation Method 1
By laser dicing, laser energy is concentrated to sublimate, melt or ionize a portion of a wafer material, thereby separating the wafer into individual devices
Implementation Method 2
laser energy is concentrated to sublimate, melt or ionize
Implementation Method 3
the adhesive climbs up along the molten material on the device side surfaces to reach a device upper surface
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A semiconductor device according to the present invention includes a mount substrate, an adhesive applied to the mount substrate, and a device having its lower surface bonded to the mount substrate with the adhesive. The surface roughness of a side surface upper portion of the device is lower than that of a side surface lower portion of the device.