Reclaimed Wafers
Unlike reclaimed wafers available in the past, the reclaimed and recycled wafers available today are of very good quality. Reclaimed wafers may be made from prime wafers which have been stripped of photo resist, oxide, poly, nitride and metals. They are mechanically repolished to remove film, surface scratches and residual patterns. After polishing, wafers are cleaned and batch sorted for thickness, bow/warp/flatness and resistivity. Thin film may then be applied to complete the process. The number of times a wafer may be reclaimed is limited, as the process physically reduces the thickness of the substrate. Eventually, test wafers become damaged, too deeply scratched or too thin to be reclaimed.

Recycled Test Wafers
The wafer recycling process involves a wet chemical etch that will remove many thin films. The process is non-mechanical. No substrate material is removed and surface flatness characteristics are not changed. Unlike wafer reclamation, this process is ineffective for removing scratches or haze. Wafers may be recycled with the proviso that they meet particular incoming specifications. Generally, for successful recycling, wafers must be free of scratches greater than a total of 3cm in length. Haze, ghost patterns and pitting must be minimal. Wafers with cracks, chips or warping cannot be recycled successfully. One of the major benefits of wafer recycling is the repeatability of the process. Wafers processed by Noel may be routinely recycled ten times or more. If recycled wafers become scratched or slightly damaged, they are flagged and may then be reclaimed. The cost-saving implications as well as the environmental benefits of this strategy are obvious.

Incoming Inspection
Upon receipt of material, Noel visually inspects wafers for chips and cracks. Wafers with these types of defects will be rejected and returned unprocessed. Noel does not offer particle specs, or surface guarantees on recycled material. Noel is not responsible for wafers broken in process.

Modifications to Noel’s Standard Specifications must be submitted in writing, prior to acceptance of order. Proprietary information - Not to be disclosed to any third party.

Wafer Recovery/Wafer Recycling

Reclaimed wafers can be created from silicon wafers stripped of photo resist, oxide, poly, nitride and metals. They are mechanically re-polished to remove film, surface scratches and residual patterns. After polishing, wafers are cleaned and sorted for thickness, bow/warp/flatness and resistance. Thin film may then be applied to complete the process.

Noel’s proprietary process removes very little silicon, which allows multiple reclaims. Other types of reclaim processes take off more silicon than our chemical process. This allows cost saving due to the reduction of having to purchase new test wafers.

Wafer recycling involves a wet chemical etch for thin film removal. Wafers must meet particular specifications if they are to be successfully recycled, e.g. they must be free of scratches exceeding a total length of 3cm. Haze, ghost patterns and pitting must be minimal. Wafers with cracks, chips or warping cannot be recycled successfully.

Wafers processed by Noel can be regularly reclaimed up to ten times. If recycled wafers become scratched or slightly damaged, they are flagged and may then be reclaimed. The cost-saving implications as well as the environmental benefits of this strategy are obvious.

Thin Film/Thermal Oxide Deposition on Test Wafers and Monitor Wafers

A cost-effective alternative to prime wafers, test wafers are used for particle monitors, oxide growth monitors, etch rate monitors, implant dosing and for characterizing new and existing equipment and processes. Test and monitor wafers may be used in very high-level work where the use of prime wafers is limited fo final evaluation.

Thermal oxide, with a 2% to 4% uniformity variation, can be frown quite easily on test wafers. Other deposited/sputtered thin films may be applied to these wafers as well. Test wafers with low TTV (Total Thickness Variation) are ideal for photolithography.

Prime Wafer Reclaim Processes

Noel Technologies delivers exceptional quality reclaimed prime wafers in 4", 5", 6", 8", and 12" sizes. These wafers meet all SEMI (Semiconductor Equipment and Materials International) specifications for these materials.

Typical reclaim wafer applications include:

• Particle monitors
• Thin film thickness measurements
• Etch rate monitors
• Equipment characterization
• Furnace barrier

Thin Film/Reclaimed Wafer Particle Measurement Services

Noel Technologies can provide customers with very tight particle specifications for thin films and reclaimed wafers, utilizing a Tencor particle-measuring tool. We accept full responsibility for the quality of a customer’s reclamation process and customized thin film.