Development of Megasonic cleaning for silicon wafers. Quarterly report No. 4

Technical Report · Tue Apr 01 00:00:00 EST 1980

DOI:https://doi.org/10.2172/5429034· OSTI ID:5429034

Mayer, A

The Megasonic system consisting of the cleaning and rinse tank, the air dryer with the belt drive, and the laser defect scanner, has now been completely assembled, debugged, and tested in the laboratory at various power levels and belt speeds. The results indicate that wafer-throughput design targets have been met and exceeded. At the recommended power input of 160 W per transducer about 4500 wafers per hour can be cleaned and at least 2600 wafer per hour can be dried in 3/32-in.-spaced quartz carriers. As experience accumulated, several sources of contamination were identified. These included turbulence in the laminar-flow air stream, causing unfiltered room air to be inducted into the working area; the temporary aluminum supports for the quartz carriers; wash water contaminated with colloid, leading to slow and inadequate rinse rate; and leaks in the seal between the laminar-flow station and the belt drive. The laser scanner was found to be an excellent diagnostic tool: the pattern of scattering centers displayed on the storage 'scope is almost always indicative of the cause of the problem, be it dust, poor water, or surface defects on the wafer. The solar-cell evaluation test carried out with 22 Megasonically cleaned and 18 system-Z-cleaned solar cells has been completed. It confirms that the Megasonically cleaned cells have higher average efficiency. However, about 17% of the Z-cleaned cells are considerably poorer than the rest; if these are not included, the distribution of the remaining 83% is statistically indistinguishable from that of the Megasonically cleaned ones. It is tentatively concluded that Megasonic cleaning produces a more uniform product with fewer really poor cells, but not cells with an efficiency greater than the maximum attained by Z-cleaned cells.

• Research Organization: RCA Solid State Div., Somerville, NJ (USA); RCA Labs., Princeton, NJ (USA)
• DOE Contract Number: NAS-7-100-955342
• OSTI ID: 5429034
• Report Number(s): DOE/JPL/955342-4
• Country of Publication: United States
• Language: English

Related Subjects

14 SOLAR ENERGY
36 MATERIALS SCIENCE
SILICON
SURFACE CLEANING
CONTAMINATION
DRYING
EQUIPMENT
IMPURITIES
LASERS
OPTICAL SCANNERS
PERFORMANCE
SILICON SOLAR CELLS
TURBULENCE
ULTRASONIC WAVES
CLEANING
DIRECT ENERGY CONVERTERS
ELECTRONIC EQUIPMENT
ELEMENTS
OPTICAL EQUIPMENT
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
SEMIMETALS
SOLAR CELLS
SOLAR EQUIPMENT
SOUND WAVES
SURFACE FINISHING
140501* - Solar Energy Conversion- Photovoltaic Conversion
360601 - Other Materials- Preparation & Manufacture