Development of a new laser process to improve productivity of high-brightness LED
DISCO Corporation (Head Office: Ota-ku, Tokyo, President: Hitoshi Mizorogi) has developed a new laser application that optimizes the optical system of the DFL7160 laser saw, which has achieved sales in Low-k grooving*1, to process a breaking groove in sapphire wafers for high-brightness LEDs. DISCO will introduce a processed sample based on this application and the processing method at SEMICON Japan 2006, which will be held from December 6 - 8.
| *1 |
Low-k grooving |
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Low-k grooving is an application that can improve reliability (prevent film peeling) in devices that use Low-k film (low dielectric constant), which is known to have weak mechanical strength. |
Application Development Background
Recently, high-brightness LEDs are being used for various applications. In the future it is forecast that the demand will continue to increase based on the expansion of applications to illumination, cars, etc.
However, the current typical singulation process by diamond scribe*2 + breaker*3 has issues such as unstable yield, dependence on operator skill and high consumable cost.
Therefore, DISCO has developed a new laser application to improve these issues. |
| *2 |
Diamond scribe |
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A diamond scribe is a process that uses a diamond crystal to scratch the workpiece surface to trigger a break along that scratch. |
| *3 |
Breaking |
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Breaking is a process that breaks the workpiece along the groove that was formed by a diamond scribe or by a laser. |
Process Outline
This process forms a groove about 15 - 30 um deep in a sapphire wafer using a laser, and then breaks the wafer from this starting point with a breaking machine. Compared to the current processes, this process realizes yield stability (stable processing using a laser), uses a machine recipe independent of operator skill and maintains nearly the same LED brightness. In addition, since it is possible to process in full automation mode from handling, alignment, grooving and cleaning to cassette loading, this method contributes to productivity improvement.
Processing of one laminated wafer at a time is typical. However, the DFL7160 sapphire specification can support multiple mounted wafers. If 2-inch diameter wafers are used, it is possible to batch process twenty-six wafers in continuous full automation mode with twelve wafers laminated onto a 300-mm diameter ring frame. (2 x 13 slot cassettes x 12 (2-inch wafers) = 312 wafers). Furthermore, by installing a shape recognition unit into the laser saw, it is possible to perform automatic alignment and scribing of irregular shaped workpieces, such as broken wafers. |
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Process Flow
Sapphire process example using a laser
After laser grooving
(microscope photograph of the die surface) |
After breaking and expanding
(microscope photograph of the die surface) |
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Sapphire Laser Grooving Merits
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Improves yield and attains stable processing with nearly the same LED brightness as the current process. |
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Improves productivity using high-speed laser grooving. |
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Improves productivity based on multiple wafer mounting (able to batch process for a long time) |
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Able to perform automatic alignment and full automatic grooving of irregular shaped workpieces, such as broken wafers, using the shape recognition function |
Comparison with the current process
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DFL7160 sapphire specification process |
Current process |
| LED Brightness |
Very good |
Very good |
| Productivity |
Good |
Fair |
| Yield (broken and defective rate) |
Good |
Poor |
| Quality stability |
Good |
Poor |
| Running cost (labor cost) |
Very good |
Poor |
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Future plans
DISCO will exhibit the DFL7160 sapphire specification at SEMICON Japan 2006 from December 6 - 8.
Test cuts for product and process evaluation can be arranged any time.
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Contact:
DISCO Corporation
Corporate Strategy Division
Management Strategy Department
Market Communications Team
Phone: 81-3-4590-1090 Fax: 81-3-4590-1094 |
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