A Comprehensive Atomistic Kinetic Monte Carlo Model for Amorphization/Recrystallization and its Effects on Dopants
- PDF / 211,447 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 50 Downloads / 177 Views
1070-E03-01
A Comprehensive Atomistic Kinetic Monte Carlo Model for Amorphization/Recrystallization and its Effects on Dopants Nikolas Zographos1, and Ignacio Martin-Bragado2 1 Synopsys Switzerland LLC, Affolternstrasse 52, Zürich, 8050, Switzerland 2 Synopsys Inc., 700 East Middlefield Road, Mountain View, CA, 94043 ABSTRACT This work shows a comprehensive atomistic model to describe amorphization and recrystallization, and its different effects on dopants in silicon. We begin by describing the physical basis of the model used, based on the transformation of ion-implanted dopants and generated point defects into amorphous pockets of different sizes. The growth and dissolution of amorphous pockets is simulated by the capture and recombination of point defects with different activation energies. In some cases, this growth leads to the formation of amorphous layers. These layers, composed of a set of amorphous elements, have an activation energy to be recrystallized. The recrystallization velocity is modeled not only depending on temperature, but also on dopant concentration. During the recrystallization, dopants can move with the recrystallization front, leading to dopant redistribution during solid phase epitaxial regrowth (SPER). At the edge of the amorphous/crystalline (A/C) interface, the remaining damage forms end-of-range (EOR) defects. Once the model is explained, we discuss the calibration methodology used to reproduce several A/C experiments, including the dependencies of the A/C transition temperature on dose rate and ion mass, and the A/C depth on ion implant energy. This calibrated model allows us to explore the redistribution of several dopants, including B, As, F, and In, during SPER. Experimental results for all these dopants are compared with relevant simulations. INTRODUCTION The semiconductor industry is systematically reducing the thermal budget allowed for diffusion of dopants while using preamorphization and SPER as a main strategy to increase active dopant concentration and to better control the doping profile on current devices. As the scenario shifts from a diffusion-controlled paradigm to a diffusion-less one, the role played by the redistribution of dopants during SPER gets more important. This optimist scenario that avoids the difficulties of modeling diffusion conveys other important problems: SPER produces dramatic changes in dopants and impurities profiles. It is the aim of this work to explore and propose a comprehensive model to predict the final doping profiles after SPER has taken place.
PHYSICAL MODEL Our simulator [1], using the kinetic Monte Carlo (KMC) technique [2,3], gets the coordinates of all the particles for each collision cascade from a Binary Collision Approximation Monte Carlo simulator. Instead of undergoing immediate IV recombination, amorphous pockets (APs) are formed, simulating disordered regions. The amorphous pockets shrink by recombining internal IV pairs with a frequency given by [4,5] IV αs β × exp(− E act ( s) / k BT ) ,
(1)
IV α, β and E act being calibr
Data Loading...
