Editorial S
E
C
T
I
O
N
S
Reticles Pick Up the Burden The inexorable drive of optical lithography continues to enable semiconductor manufacturers around the world to print increasingly smaller linewidths on larger and larger silicon wafers. Despite dire predictions that we have seen the “end,” optical lithography continues to push the envelope and stretch perceived limits with amazing regularity. The resulting ability for wafer fabs to delay investments in shorter wavelength exposure tools far beyond what was optimistically contemplated a decade ago has saved billions of dollars in capital. This has also enabled the semiconductor industry to shrink linewidths on an accelerated schedule, creating accelerated cash flows and staggering increases in shareholder value. The reticle has increasingly become a central player in this economic and technological windfall. The industry has transferred some of the burden of smaller wafer linewidths and critical dimension (CD) control from optical exposure tools to more precise and complex reticles. Because of bin yield, CD control is worth about $1 per chip per atom in linewidth precision. While there is much discussion regarding accelerated roadmaps for wafer processing, the dimensions that are important on a reticle have dropped at least twice as fast as those on the wafer, to compensate for the slowdown in adoption of next wavelength exposure tools. The burden, and the source of value, has shifted. Reticles have become amazingly more complex, endowed with billions of optical proximity correction (OPC) features and enhanced by phase shift mask (PSM) topography that minutely adjusts the wavefront of deep ultraviolet (DUV) light. Stretching physics in what is termed “sub-wavelength lithography,” we now print lines smaller than the wavelength of the DUV light used to expose them. 4
Autumn 2000
Yield Management Solutions
Unfortunately, in sub-wavelength lithography small errors on the reticle are multiplied by a mask error enhancement factor that magnifies the effect of defects and CD errors. In a reticle image measuring 1 million by 1 million pixels (representing a photo-mask for 0.13 micron technology from an inspection standpoint), a single 100 nm by 100 nm defective pixel can kill production at a rate of one hundred 300 mm wafers per hour. A few years ago, the area of a critical defect ten times as large on a reticle was only one-tenth as complex. Given this complexity, it is clearly evident that reticle quality is key to economically viable advanced lithography and semiconductor manufacturing. The leverage on the finding and eliminating of nano-scale defects has enormous economic value, the cost of developing and operating these systems is tremendous. It is a battle of exponentials: exponentially more expensive development efforts build equipment that deals with exponentially more pixels in exponentially larger end-user markets. Between the equipment makers and the end users are many commercial levels. Closest to the reticle equipment manufacturers are the mask makers. After years of Darwinian consolidation, the remaining captive and merchant reticle manufacturers compete to cost-effectively provide the semiconductor industry with total state-of-the-art reticle solutions. Each of these manufacturers (the out-source suppliers to the chip industry) adds value through reticle process integration. They select the best-of-class writers, inspectors, metrology equipment, etch and repair tools, and integrate them with proprietary process and manufacturing know-how to produce tailored products for their markets. Given the critical importance of the reticle, the lethal significance of reticle defects, the risks of yield crashes, and the exponential nature of the economics,
Yield Management S O L U T I O N S
EDITOR-IN-CHIEF Kern Beare MANAGING EDITOR Uma Subramaniam
it is little wonder that second-place tools have struggled in this market. This trend will only accelerate as the economic value and the fragility and risk of the reticle grows. While the equipment hardware is easily visible, information technology is the force multiplier. Today’s big “hardware” projects have as many software engineers as all other types of engineers combined. This equipment is then integrated into information architectures that add value through information exchange, correlation and presentation. Today’s reticles are printing the microchips that power the information architectures that are helping accelerate the semiconductor roadmap, increase yield and reduce cost. The future lies with best-in-class equipment and instruments connected in advanced information systems that feed the semiconductor cycle. circle RS#046
CONTRIBUTING EDITORS Thomas Salinas Carol Johnson Indira Rangarajan ART DIRECTOR AND PRODUCTION MANAGER Carlos Hueso D E S I G N C O N S U LTA N T Harry Wichmann C I R C U L AT I O N A N D A S S O C I AT E E D I T O R Cathy Correia
KLA-Tencor Worldwide C O R P O R AT E H E A D Q U A R T E R S
KLA-Tencor Corporation 160 Rio Robles San Jose, California 95134 408.875.3000 I N T E R N AT I O N A L O F F I C E S
KLA-Tencor France SARL Evry Cedex, France 011 33 16 936 6969
Lance A. Glasser Vice President and General Manager Reticle and Photomask Inspection Division
KLA-Tencor GmbH Munich, Germany 011 49 89 8902 170 KLA-Tencor (Israel) Corporation Migdal Ha’Emek, Israel 011 972 6 6449449 KLA-Tencor Japan Ltd. Yokohama, Japan 011 81 45 335 8200
Lance Glasser is Division Vice President and General Manager for KLA-Tencor’s Reticle and Photomask Inspection Division. Lance’s most recent assignment has been RAPID Division Vice President of Advanced Programs. In this position, Lance was the program manager in charge of the TeraScan™, RAPID’s DUV reticle inspection system. Since joining KLA-Tencor in 1996, Lance has been a key member of the management team that has led the RAPID division to record revenues, profits and a dominant market position. Before joining KLA-Tencor, Lance was Director of Electronics Technology at ARPA and before that he served on the M.I.T. faculty in Electrical Engineering and Computer Science. Lance received his Ph.D. in Electrical Engineering and Computer Science at M.I.T. Autumn 2000
KLA-Tencor Korea Inc. Seoul, Korea 011 822 41 50552 KLA-Tencor (Malaysia) Sdn. Bhd. Johor Bahru, Malaysia 011 607 557 1946 KLA-Tencor (Singapore) Pte. Ltd. Singapore 011 65 782 6788 KLA-Tencor Taiwan Branch Hsinchu, Taiwan 011 886 35 335163 KLA-Tencor Limited Wokingham, United Kingdom 011 44 118 936 5700
Yield Management Solutions
5