Millisecond Microwave Annealing: Reaching the 32 Nm Node
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MILLISECOND MICROWAVE ANNEALING: REACHING THE 32 NM NODE Keith Thompson1, John H. Booske2, R.L. Ives1, John Lohr3, Yurii A. Gorelov3, Ken Kajiwara3 1. Calabazas Creek Research 2. University of Wisconsin 3. General Atomics
ABSTRACT The next generation of Si devices requires thermal treatments of 1200oC – 1300oC but can only withstand temperatures above 800oC for a few milliseconds. Current rapid thermal processing techniques cannot meet these requirements. We have designed, constructed, and tested a microwave reactor that heats Si to 1300oC in only a few milliseconds and cools the wafer at a rate that exceeds a million degrees per second. Applying millisecond microwave annealing to ultra-shallow junction formation in advanced Si devices shows that this technique meets or exceeds the thermal processing requirements for the next several generations of Si devices. INTRODUCTION High temperature thermal processing: (1) drives dopant diffusion, (2) dilutes the dopant concentration, (3) stimulates unwanted lateral dopant redistribution, and (4) degrades high-k gate dielectrics [1-4]. As Si devices scale to the 65 nm node and beyond, post-implant anneals must increase the volumetric concentration of active dopants and thoroughly repair the implant damage while simultaneously reducing the overall thermal budget to minimize the just-mentioned issues. According to the International Technology Roadmap for Semiconductors (ITRS) [5], by 2013, physical gate lengths will shrink to 18 nm, requiring junction depths of 9 nm or less. Current rapid thermal processing (RTP) systems ramp and cool the wafer temperature at rates on the order of 200oC/sec. While these thermal budgets satisfy the 90 nm node [57], the logical next step is to develop RTP systems that heat and cool at several hundred thousand degrees per second. Recent reports by Vortek indicate success with this strategy when high powered arc-lamps were employed to heat 300 mm diameter wafers to 1300oC on millisecond time scales [8,9]. We have designed, constructed, and tested an analogous microwave reactor, which is capable of heating Si wafers to 1300oC in only a few milliseconds.
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EXPERIMENTAL APPARATUS The microwave source was a 110 GHz 1 MW gyrotron at the DIII-D National Fusion Facility [10,11]. The footprint of a gyrotron system is comparable to many other semiconductor manufacturing tools, such as standard plasma etch or deposition systems. A typical high-power continuous-wave, gyrotron system weighs approximately 1800 kg (including the magnet). A floor space of six feet by six feet with a ten-foot high ceiling accommodates the entire system and its peripherals. No special precautions are necessary to house and to operate the gyrotron other than those normally associated with high voltage equipment. It is anticipated that the gyrotron and power supply would be located outside of any clean room environment with power transmitted through a low loss, overmoded waveguide. A modified waveguide transmission line directed the microwave beam into the microwave-
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