Modeling Ultra Shallow Junctions Formed by Phosphorus-Carbon and Boron-Carbon Co-implantation
- PDF / 217,918 Bytes
- 6 Pages / 595 x 842 pts (A4) Page_size
- 32 Downloads / 214 Views
0994-F11-17
Modeling Ultra Shallow Junctions Formed by Phosphorus-Carbon and Boron-Carbon Co-implantation Christoph Zechner1, Dmitri Matveev1, Nikolas Zographos1, Victor Moroz2, and Bartek Pawlak3 1 Synopsys Switzerland LLC, Affolternstrasse 52, Zurich, CH-8050, Switzerland 2 Synopsys, Incorporated, 700 East Middlefield Road, Mountain View, CA, 94043 3 NXP Semiconductors, Kapeldreef 75, Leuven, B-3001, Belgium ABSTRACT A new carbon-interstitial clustering model has been developed. The model has been implemented into the process simulator Sentaurus Process. Model parameters have been calibrated using fundamental marker layer experiments. B diffusion retardation in the C doped layer as well as Sb diffusion enhancement in the region close to a layer with high C concentration are successfully simulated. The calibrated model has been applied to simulations of ultra-shallow junction formation by high dose P-C and B-C co-implantation. It is assumed that, in regions which are amorphized by ion implantation and recrystallized by solid phase epitaxy, C is in the substitutional state right after the recrystallization. In contrast, in non-amorphized regions, C is assumed to be in clusters at the beginning of thermal annealing. A good agreement between simulation and experimental results has been achieved. The dependence of dopant diffusion on implanted C dose and spike annealing temperature has been reproduced. INTRODUCTION The continued scaling of CMOS transistors requires a formation of very shallow, abrupt dopant profiles with high activation level. Recently, it was found that C coimplantation could suppress the transient enhanced diffusion (TED) resulting in a box-like dopant profile shape. [1-3] On the other hand, B activation is reduced in the presence of C [1]. Those phenomena were attributed to the formation of carbon-interstitial clusters [4,5]. Modeling the interaction between C and point defects becomes important for the development of new ultra-shallow junction formation techniques. In this work, we apply a newly developed carbon-interstitial clustering model to simulation of P-C and B-C codiffusion. MODEL C is known to diffuse via carbon-interstitial pairs [5]. The carbon-interstitial pairing reaction rate can be written as follow
Rkick-out = Dc /(λ2 CIi*) (CS CI – (DCI /DC) CI* CCI ) CS and CCI are the substitutional C and carbon-interstitial pair concentrations respectively. DC is the effective (measured) C diffusivity, DCI is the diffusivity of carbon-interstitial pairs, CI* is the interstitial equilibrium concentration, CIi* is the interstitial equilibrium concentration in intrinsic silicon, λ is the carbon-interstitial pair hopping distance. It is also known that C forms clusters with interstitials [4,5]. In the literature, many cluster types have been proposed, ranging from the C2I cluster up to big clusters like C6I6. We use an approach similar to the one proposed by Colombeau and Cowern [4]. Our model includes three neutral cluster species: C2I, C3I2 and C3I3. The following reactions are taken into accou
Data Loading...
