Majlesi Journal of Electrical Engineering Vol. 11, No. 4, December 2017 37 Simulation of the Process of LDMOS Transistor Manufacture and Optimizing it to Increase the Current of Work Payman Bahrami 1 , Mohammad Reza Shayesteh 2* , Mohammad Eslami 3 1- Department of Electrical Engineering, Yazd Branch, Islamic Azad University, Yazd, Iran. Email: payman.bahrami@gmail.com 2- Department of Electrical Engineering, Yazd Branch, Islamic Azad University, Yazd, Iran. Email: shayesteh@iauyazd.ac.ir (Corresponding author) 3- Department of Electrical Engineering, Yazd Branch, Islamic Azad University, Yazd, Iran. Email: m.eslami@iauzah.ac.ir Received: June 2017 Revised: July 2017 Accepted: September 2017 ABSTRACT: This paper presents the simulation of the process of LDMOS transistor manufacturing by using Silvaco software and by relying on the ability of calculating the basic parameters of transistor dependencies, focusing on the optimization of the manufacturing process in order to increase the current of work. By using this simulation and reviewing each parameter, we can achieve the optimized manufacturing process by focusing each basic parameter and by paying attention to its required application. In order to design, we first define the construction procedures and the necessary processes using the Athena simulator, and then we use the Atlas device simulator to acquire electrical parameters. Simulation results show that by selecting the optimal parameters of the manufacturing process such as gate oxide thickness, channel length, and doping in channel, we can increase current of the LDMOS transistor. KEYWORDS: LDMOS transistor, Current operating point, Threshold voltage, Cut-off frequency, Trans conductance, Breakdown voltage. 1. INTRODUCTION The application of high power radio frequencies is growing respectively due to demands for wireless equipment market. Transistors with metal oxide semiconductor field effect (MOSFET) have been used in high power radio frequency systems due to their high-speed switching [1], [2]. This type of transistors also has a wide range of maximum voltage rating between 10 to 1500V for power application. Voltages rating less than 30V are usually used for power switches in portable electronic equipment including laptops, personal computers and etc. voltage ranges between 30 to 100 volts are used in the industry and car manufacturing. Voltages higher than 100V are generally used to control motors, power devices, and communications. In the past decade the laterally diffused metal oxide semiconductor (LDMOS) transistor has baeen the dominating technology for use in the RF-power amplifiers. We require a short channel length and low impurity level in drain area for power applications [3]. Having low impurity level guarantees the spread of channel into the area in drain association [4-8]. Current depends on different parameters such as gate oxide thickness, threshold voltage, width and length of channel, and channel voltage [9]. Threshold voltage also depends on the gate oxide thickness, and the surface concentration of the channel. Therefore, by changing the thickness of the oxide, implanting channel, and adjusting channel length in simulation process, we can increase current without causing change in other default parameters [10-14]. The breakdown voltage of the device depends on the thickness and resistance of epitaxy layer, the shape of the junction, and structure of the area in which junction reaches to the semiconductor surface [15]. It is predicted that by increasing the thickness of epitaxy layer and resistance of epitaxy layer, breakdown voltage will increase [16], [17]. Several methods to improve the breakdown voltage, on-resistance, and high-frequency operation of the LDMOS transistor have already been developed [18-20]. However, this work focuses on the optimization of manufacturing process in order to increase the current of LDMOS transistor. The simulation of manufacturing process of this type of transistor which is a base for its real manufacturing is of the utmost importance. In this paper, we describe physical structure and manufacturing processes of LDMOS transistor. We determine parameters that affect the device current of work. Also, optimizing the current of the transistor by changing the thickness of oxide, thickness of the