– 1 – OPTIMIZATION OF ION IMPLANTATION USING TRIM SOFTWARE FOR THE FORMATION OF SHALLOW N + /P JUNCTION IN GERMANIUM SUBSTRATE Umar Abdul Aziz 1,a , Nur Farhana Arissa 1,b , Siti Rahmah Aid 1,c, ,Hafizal Yahaya 1,d , Anthony Centeno 1,e , Satoru Matsumoto 1,f , Akira Uedono 2,g , David McPhail 3,h 1 Malaysia-Japan International Institute of Technology, Universiti Teknologi Malaysia, Jalan Sultan Yahya Petra, 54100 Kuala Lumpur, Malaysia 2 Faculty of Pure and Applied Science, University of Tsukuba, Tsukuba, Ibaraki 305-8573, Japan 3 Department of Material, Imperial College London, SW72AZ, England, United Kingdom a umarizkh@yahoo.com.my, b nurfarhanaarissa@gmail.com, c sitirahmah.aid@utm.my (corresponding author), d hafizal.kl@utm.my, e anthony.kl@utm.my, f matsumoto@utm.my, g uedono.akira.gb@u.tsukuba.ac.jp, h d.mcphail@imperial.ac.uk ABSTRACT Silicon (Si) device down-scaling is facing a big challenge to maintain its high drive current capability along with lower leakage current. Due to its similarities with Si, the interest has been focused on Germanium (Ge) as a substitute for device substrate. However, there are major problems in fabricating complementary metal-oxide semiconductor (CMOS) devices i.e. poor dopant solubility, low dopant activation and large dopant diffusion coefficient. These required further optimization on fabrication parameters involving ion implantation process. This paper reports the optimization of ion implantation parameters such as energy and dose. Co-implantation technique employing two atoms with different size will be adopted for forming the shallow n + /p junction in Ge. The stress associated with atomic size is expected to be introduced into the Ge lattice. This stress will be manipulated to enhance dopant activation while controlling the diffusion. Low energy of dopant-ion implantation is selected to achieve high dopant concentration near the surface. The simulation parameters of two atoms were arranged to get such result where the effect of stress from co-implantation process can be manipulated. Keywords — co-implantation, dopant distribution, amorphous layer, defect vacancies, germanium, np junction 1. INTRODUCTION According to the International Technology Roadmap for Semiconductors (ITRS) 2010, it is reported that the traditional scaling of planar Si-CMOS devices is becoming difficult due to the physical limit in down-scaling dimension. Germanium (Ge) and III-V compound have been pointed out as a new material candidate for pMOS and nMOS devices, respectively. This is due to the material properties that could improve the density, energy efficiency and reliability of the devices. However, the utilization of the same material for both nMOS and pMOS devices is important in order to reduce the process complexity and cost in manufacturing process. The interest has been focused on Ge due to similarities with Si and its higher carrier mobility (i.e. two times higher mobility for electrons and four times for holes compare to Si) [1–5]. One of the process involve in manufacturing CMOS devices is the fabrication of the pn junction. Two major processes that will be employed in the fabrication of pn junction are ion implantation and thermal annealing. However, unlike Si, there are many problems related to the dopant electrical activation and diffusion behaviour in Ge substrate during the fabrication process [5-9]. Since dopant activation and diffusion are controlled by the interactions between dopant and defects, it is important to control the defects introduced in the substrate by ion-implantation process. Aggressive change or uncontrollable processing parameter can enhance these dopant-defect interactions which result in anomalous characteristics of the devices. Previous studies have revealed that fabrication of nMOS is facing severe problem compare with pMOS [9]. This is due to the heavy dopant ions i.e. arsenics (As) or antimony (Sb) is widely used for n-type dopant ion implantation results in more damages/defects. Furthermore, Ge easily forms unstable oxide on the surface which also can induce defects into the substrate [10]. Consequently, these damages/defects give substantial effect on the dopant electrical activation and diffusion during the thermal annealing process. Therefore, it is important to select appropriate atoms and process parameter to reduce the damages/defects introduced by ion- implantation during the formation of n + /p junction. Co-implantation is a technique where two atoms with different sizes are implanted together in the substrate. The