Two Dimensional Numerical Thermal Analysis of Silicon on Insulator Recrystallization Processes by a Moving Heat Source
- PDF / 388,850 Bytes
- 9 Pages / 420.48 x 639 pts Page_size
- 27 Downloads / 194 Views
TWO DIMENSIONAL NUMERICAL THERMAL ANALYSIS OF SILICON ON INSULATOR RECRYSTALLIZATION PROCESSES BY A MOVING HEAT SOURCE
C.Y. Chang, Y.K. Fang and B.S. Wu, R.M. Chen Institute of Electrical & Computer Engineering National Cheng Kung University Tainan, Taiwan, Rep. of China
ABSTRACT The moving-zone melt recrystallization of polysilicon on insulator substrate has been studied with computer simulation methods. The most important parameters such as upper strip heater moving velocity, the power of upper strip heater, substrate temperature were investigated. Generally speaking, temperature profile in multilayer and melt depth of polySi are difficult to be visualized, but are still important for recrystallization process. Therefore by using two dimensional finite difference method, a numerical analysis of moving melt zone recrystallization processes has been developed. Through this analysis, the temperature profile in multilayer and melt depth of poly-Si are depicted.
I.
INTRODUCTION
Melting and recrystallization of poly-Si film with a "Moving zone melt" heat source has been shown to improve its electrical properties (1,2) so that MOSFET can be fabricated with their active channels in the poly-Si layer by zone-melting recrystallization. The structure of the polysilicon has been shown to depend on the local temperature and temperature gradients during recrystallization r 3) . Also, A. Gat and J.F. Gibbons ( 4) reported that the entire thickness of the polysilicon must be melted to obtain the large-grain structure necessary for device fabrication. Therefore, "moving-zone-melt recrystallization" depend more critically on the detailed temperature distribution in the polysilicon film. Hence, we developed a numerical method to solve the heat equations which is derived as a function of position and relate this distribution to the structure of the recrystallized polysilicon. Through this analysis, the temperature profile in multilayer and melt depth of poly-Si are depicted. Thus in turn, the effects of moving speed and power dissipation of upper strip heater, and substrate temperature on the film quality are correlated. Here, emphasis has been applied to a particular moving heat source specifically a hot graphite strip with large aspect ratio. However, the numerical solution is sufficiently general for use with other recrystallization techniques including scanning laser annealing and electron-beam thermal processing.
II.
SIMULATION STRUCTURE
in Fig.1 is illustrates The simple multilayered structure which includes three layers-polysilicon, silicon dioxide, Really, we simulate the two layers-polysilicon, silicon. single Mat. MS. Soc. Symp. Proc. Vol. 23 (1984)QElsevier Science Publishing Co., Inc.
498
dioxide where heat equations is generated. Single silicon silicon layer is individually processed by a simple model which we assume the two dimension heat transfer is the same as one dimension heat transfer. At the same time, it is assumed that the respective thermal parameters are independent of temperature and position. The
Data Loading...
