Electromagnetic fast firing for ultrashallow junction formation

Abstract

Abstract-The creation of low resistivity, ultrashallow source/drain regions in MOS device structures requires rapid thermal processing (RTP) techniques that restrict diffusion and activate a significant percentage of the implanted dopant species. While current heating techniques depend upon illumination based heating, a new technology, electromagnetic induction heating (EMIH), achieves a rapid heating of the silicon by coupling electromagnetic radiation directly into the silicon wafer. Heating rates of 125 C s to temperatures in excess of 1050 C have been achieved for 75-and 100-mm-diameter wafers at input powers of 1000 and 1300 W, respectively. These ramp rates are suitable for ultrashallow junction formation, and junctions shallower than 30 nm with sheet resistances lower than 600 /square have been achieved. This paper details the application of electromagnetic heating using radiation in the microwave, 2450 MHz, frequency regime. Experimental results, comparing microwave annealed implants to the well documented SEMATECH requirements, and simulations, utilizing a coupled electromagnetic-thermal computer model, of the heating process are discussed.

Millisecond microwave annealing: Driving microelectronics nano

“…Previous microwave heating experiments were performed with magnetron sources, 22,27,28 which operate between 300 MHz and 3 GHz. Magnetrons typically provide a few kilowatts of power but on occasion have been designed to provide several MW of power.…”

“…27,28 Unfortunately there are several drawbacks to implementing this technique for millisecond heating applications. The impedance of Si, on the other hand, varies dramatically with temperature and frequency.…”

“…22,27,28 Building on this past work, we have designed and constructed a microwave reactor capable of heating full scale 200 and 300 mm diam wafers to 1300°C in only a few milliseconds. High-temperature processing, however, is critical to recrystallize the Si lattice, i.e., repairing the implant damage, and to move the implanted dopants into lattice sites where they contribute to the electrical characteristics of the Si.…”

Localized annealing of polysilicon microstructures by inductively heated ferromagnetic films

“…The use of insulating wafers simplified the process requirements as the electrical resistivities of insulators prevent efficient inductive heating, and it is certain that the maintenance of localization would be much more difficult with semiconducting wafers as will be discussed further in the next chapter. At nearly the same time, researchers at the University of Wisconsin also began to publish results on wafer bonding [Thompson, et al, 2002] as well as dopant activation [Thompson, et al, 2001;Thompson, et al, 2003] using their electromagnetic induction heating (EMIH) technology. This research focused on electromagnetic coupling directly to silicon wafers, making use of the larger volume of the substrate to overcome the lower conductivity with respect to metals.…”

“…Due to electromagnetic skin effects, induced temperatures were at a maximum at the wafer edges, and in the case of the radio frequency (RF) bonding of 75mm wafers a gradient was observed such that the temperature at the center was only approximately 780 o C. Bonding was nevertheless found to be complete, and the authors hypothesized that RF electric fields present at the bonding interface may have enhanced reaction kinetics such that the temperature requirement was reduced. The authors have similarly published results on the use of EMIH for dopant activation, making use of its high efficiency to demonstrate the utility of the rapid rate of temperature increase to achieve shallow dopant activation [Thompson, et al, 2003]. The next generation of active devices requires enhanced control over junction depths, and rapid drive-in processes such as rapid thermal annealing (RTA) are becoming necessary in order to achieve sufficient dopant activation with limited diffusion.…”