An alien technology for assembling ICs

By Debra Vogler
WaferNews Technical Editor

Gravity, one of the most familiar forces of nature, is at the heart of Alien Technology’s fluidic self-assembly (FSA) process. FSA is a technique to assemble ultra high volumes of crystalline silicon drivers into plastic substrates for displays, RF ID tags, and other portable electronic devices.

The FSA process starts with forming ICs into trapezoidal shapes (called NanoBlocks) with a 54.7 degrees beveled cut using CMP and crystalline-plane-specific chemical etching. The ICs can range in size from 10-micron to several hundred microns on a side. When suspended in an aqueous solution over receptor holes in the display, the ICs fall into place, literally. The receptor holes, which have been micro-embossed into the substrate, match the size and shape of the NanoBlock ICs and are placed with an accuracy of +/- 1-micron. The company credits the use of chemical etch instead of a die cutting saw for being able to achieve a ~10-micron etching street vs. the typical 100-micron sawing street.

The law of large numbers governs the actual results of the fall into receptor holes. Those ICs that don’t make it are removed from the fluid, cleaned and re-used. A polymer coating on the surface of the aqueous solution prevents damage of the NanoBlocks. Alien, of Morgan Hill, CA, claims a yield rate in excess of 99%.

Tapping the mass consumer markets means keeping costs low – the main reason Alien decided to implement the FSA process on flexible (rather than rigid) displays, for mass production.

“The TABlike (tape automated bonding) design rules are compatible with our initial product – embedded displays for Smart Cards,” explains Anne Chiang, VP of product engineering and displays. “We’ve chosen to use continuous roll-to-roll manufacturing to meet low cost/high volume objectives.”

The production line is planned to be operational in 2003.

The company is staking its future on its ability to be able to place between two and four million ICs/hour, or more, within the next year. Company VP of finance and CFO John Hemingway believes the company’s sweet spot is in being able to assemble tens of millions and even billions of ICs for pennies – a feat that he thinks can be accomplished in 2004.

Being able to assemble hundreds of billions of ICs for only pennies is becoming increasingly important. Kevin Ashton, executive director of the Auto ID Center at the Massachusetts Institute of Technology, has presented data showing that top-ranked consumer products companies will need more than 550 billion smart tags per year for tracking merchandise. For example, Coca-Cola has an expected need to track 200 billion units/yr in its supply chain, the US Postal Service, 205 billion, and Wal-Mart, 30 billion. The center is focused on the premise that by embedding intelligence into physical objects, consumer goods become able to communicate with each other, with businesses and with consumers.

While Alien Technology first started using FSA to package ICs for the displays used in smart cards, it believes the market for RF ID tags will be a much more potent market. “Right now, the price per RF ID tag is high – about $0.30 to $1.00 or even higher depending on the operating frequency and functionality,” explains Chiang. “But we can get the price down to about $0.05/tag in 2004.”



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