ÿþ<HEAD><TITLE>Aug-1998: ADP ֪ͨ£ºSemiconductor European</TITLE> <META content="Based in Silicon Valley, California, Tru-Si Technologies is the world leader in manufacturing its proprietary Atmospheric Downstream Plasma (ADP) equipment for semiconductor wafer processing applications." name=description> <META content="Processing Equipment, flat panel display, cleaning equipment, dry etch systems, photoresist application, stripping systems," name=keywords> <META content="Tru-Si Technologies" name=Name> <META content="text/html; charset=windows-1251" http-equiv=Content-Type><LINK href="trusi.css" rel=stylesheet title=style type=text/css></HEAD> <BODY><BR> <H2>ADP takes off, Semiconductor European</H2> <CENTER> <TABLE border=0 width="95%"> <TBODY> <TR> <TD> <H3>Publication: Semiconductor European</H3> <H4>A new start-up promises to revolutionize wafer thinning and boost chip packaging density</H4>. <IMG align=right height=183 src="articlescp1.gif" width=144>At Semicon West, recent venture capital start-up Tru-Si Technologies exhibited its new Tru-Etch 3000 system, a version of its proprietary Atmospheric Downstream Plasma etching and non contact handling technology for backthinning wafers up to 300mm. Thinner ICs are needed for advanced packaging applications and better heat dissipation. The system accompanies the Tru-Etch 2000 200mm version announced at April's Semicon Europa. The rapid introduction of, successively, systems for current and next-generation production is in keeping with the company's dynamic start-up and the confidence and interest in its innovative technology (see feature article, June 1998, p31-33). Tru-Si Technologies was founded jointly by Dr. Sergey Savastiouk (president and CEO) and Dr. Oleg Siniaguine (Chief Technical Officer) in 1996. Savastiouk had been teaching and researching at Santa Clara University since 1993 but brought experience of dealing with start-up companies and raising venture capital while Siniaguine brought ideas on the technology. After writing a business plan, their first action was to hire the law firms Cooley Godward and Skjerven Morill, known as the best in Silicon Valley for corporate legal activities for start-up companies and intellectual property/patent protection, respectively. With this help, they attracted $8m of venture capital from private investors (Silicon Valley's 'angels') and, in 1997, started hiring engineers and building the company and the system. <BR><BR><A name=advisors></A>Accompanying Savastiouk and Siniaguine at the launch at Semicon West were Tru-Si's board of advisors, which includes: <UL> <LI>Dana Ditmore (ax-president of Applied Materials in North America) <LI>Marc DiOrio (ax-executive VP DISCO Hi-Tech America grinders) <LI>Martin Hammond (ex-VP marketing Mattson, ex-VP Technology Lam) <LI>Chuck Desmond (ex-VP sales and services Tegal, SVG), <LI>George Lee (director of SEMI's 300mm initiative). </LI></UL>more than one of whom said Tru-Si was the best example of a start-up company they had seen in the industry. Another round of financing is planned soon. <BR><BR> <H4>APPLICATIONS OF ADP</H4>Advantages of the system compared to traditional methods are: (i) it is the only one-step process for both wafer thinning (much faster than both CMP and wet etching) and the removal of stress/damage (left by mechanical grinding), (ii) mechanical grinding can only thin down to 200-250 µm and causes mechanical stress/damage, wafer fragility and susceptibility to handling damage. ADP can thin down to 50-100 µm without inducing such fragility. (iii) also, the wafer is levitated contact free in an inverted holder: gas is blown from the centre of the holder outwards between the holder and the top surface of the wafer, escaping around the edges - not only does the gas flow create a 'Bernoulli effect' (negative-pressure lifting the wafer like an aircraft's wing), which eliminates mechanical stress, it also isolates the circuitry from etch gases, eliminating the need for expensive and potentially stress-inducing front-side wafer protection. (iv) it does not require hazardous chemicals (as do CMP and wet etching). <BR><BR>Target markets are ultra-thin packaging applications such as smart cards and cellular phones which will require chip thicknesses down to 75150 µm says Tru-Si. In 1995 only 8.2% of all ICs required thinning, but this is estimated to rise to 21.5% by the year 2000, especially as wafer thickness is greater for 300 mm wafers. <BR><BR>Savastiouk says that ADP technology can also be used in bare wafer manufacturing for final stress and damage removal after lapping, CVD and FPD processes. Due to the low wafer temperature, even wafers with ink dots or solder bumps can be thinned. <BR><BR> <CENTER> <TABLE border=0> <TBODY> <TR> <TD align=middle><IMG height=185 src="articlescp2.gif"></TD></TR> <TR> <TD><FONT size=2>Schematic (above) shows the electrode chambers which supply the plasma gas, controlling magnets, and the reactant gas injected through the high temperature plasma. Downstream from the plasma charged particles quickly lose energy (to 150-350°C) and electrically recombine before etching the wafer at a much higher particle flux than in vacuum. The 'NoTouch' non contact wafer holder (top) blows inert gas radially outwards in the gap between the holder and the wafer, creating 'Bernoulli effect' negative pressure lift as well as chemical isolation of the top side of the wafer from etchant gases. </FONT><BR><BR></TD></TR></TBODY></TABLE></CENTER> <H4>PLASMA ETCHING IN AIR</H4>The ADP source has two electrode units directed upwards and at an angle of 90° to each other (see Figure 1). Mainstream plasma gas (usually argon), injected into the chamber, exits through the water-cooled orifice to create a precisely controlled atmospheric pressure plasma of high-energy activated species (temperature 1O,OOOK and velocity of about 10m/s). <BR><BR>Reactant gases are injected into this plasma where they are chemically decomposed The (atmospheric pressure) downstream plasma is thermal due to the small mean free path of the plasma species (&lt;1 µm so the kinetic energy of the ions, electrons and neutrals is very low (&lt; 1 keV). Charged species quickly recombine and the wafers being processed have a low floating potential so, unlike vacuum: plasmas, there is neither high-energy electron-ion bombardment damage nor electrostatic charging of dielectric surfaces on the wafer. Because of the relatively high pressure (particle density in an atmospheric plasma with a temperature of 6-1O,OOOK is about 10<SUP>18</SUP>/cm<SUP>3</SUP>), these is a high particle flux of about 10<SUP>20</SUP> particles per cm<SUP>2</SUP>/second to the processed surface, producing etch rates at least 100 times greater than conventional vacuum plasma. <BR><BR>By operating at atmospheric pressure and because reactant gases (including fluorocarbons) are fully decomposed by the plasma, a vacuum system and hazardous waste disposal equipment are not required. Gaseous reaction products can be removed with a simple water-based effluent scrubber. Many applications being considered can be accomplished in a clean air minienvironment.<BR><BR></TD></TR></TBODY></TABLE></CENTER> <HR SIZE=2 width="80%"> <CENTER><B>Tru-Si Technologies</B><BR>657 N. Pastoria Ave. <BR>Sunnyvale, CA 94085 <BR>Phone: (408) 720-3333<BR>Fax: (408) 720-3334<BR>Email: <A href="mailto:inform@trusi.com">inform@trusi.com</A><BR><A href="http://www.trusi.com/" target=_top>Tru-Si Technologies Home Page</A><BR></CENTER><BR><BR></BODY>