Frédéric Morancho

A New Junction Termination Using a Deep Trench Filled With BenzoCycloButene

A new junction termination for high-voltage devices using a deep trench filled with dielectric, which dramatically decreases the junction-termination area, is proposed and fabricated. The termination breakdown voltage dependence on the dielectric critical electric field (E Cd) and its permittivity (¿rd) is theoretically studied. Finally, the proposed junction termination is experimentally validated using BenzoCycloButene (BCB) as dielectric material. Experimental results show that the proposed termination sustains more than 1200 V with a 70-¿m-width and 100- ¿m-depth trench filled by BCB.

Vertical N-channel FLIMOSFETs for future 12 V/42 V dual batteries automotive applications

In this paper, new Vertical FLI-MOSFETs dedicated to automotive applications are proposed for the first time: in these devices, only one P Floating Island is introduced in the N/sup -/ epitaxial region. In term of specific on-resistance/breakdown voltage trade-off, it is shown that the FLIMOSFET exhibits better performance than the conventional VDMOSFET and approaches the well-known silicon limit. This is due to the strong reduction of access (R/sub a/.S) and drift (R/sub b/.S) resistances, because of the increase in the N/sup -/ epitaxial layer doping concentration. In other words, the FLIMOSFET appears to be one of the best Power MOSFET in low voltage applications.

Feasibility study of a junction termination using deep trench isolation technique for the realization of DT-SJMOSFETs

In this work, a new design of high voltage (1200 Volts range) power superjunction MOSFET (SJMOSFET) is presented: the deep trench SJMOSFET (DT-SJMOSFET). Besides, a new junction termination, consisting in a 70 mum width and 100 mum depth trench filled by a dielectric, is proposed. Simulation results show that this junction termination exhibits the same blocking voltage capability as the base cell (central cell). In addition, the termination breakdown voltage dependence on the dielectric critical electric field (ECd) and its permittivity (epsivrd) is studied. Finally, the possibility of filling the trench termination using low dielectric polyimide such as BenzoCycloButene (BCB) is successfully approved and the Chemical Mechanical Polishing of BCB is also discussed. These experimental results represent the key steps for a future complete fabrication process of DT-SJMOSFET.

A New Optimized 200V Low On-Resistance Power FLYMOSFET

Nowadays, the on-resistance reduction is key factor in the evolution of power devices, especially in power MOSFETs technology. In that way, innovating structures such as superjunction (SJ) [1] or floating islands (FI) [2, 3, 4] devices have been developed. Previously, a vertical N-channel FLYMOSFET, including one level of P buried layers called floating islands (introduced in the N-epitaxial region), has been successfully developed [5, 6]. In this paper, new design and process improvements provide for the first time a FLYMOSFET with two levels of FI exhibiting a low specific on-resistance (RON-S) of 4.5 mOmega.cm2 in 200 V breakdown voltage (BVdss) range which breaks the silicon limit [7]. Furthermore, a full physical and electrical characterization is presented, especially in dynamic configuration to evaluate FLYMOSFETs performances. Then a manufactured 200 V SJ product from another company is analyzed and compared to it. FLYMOSFET appears as a good alternative to 200 V SJ devices.

A new concept of enhanced-mode GaN HEMT using fluorine implantation in the GaN layer

In this paper, a new concept of normally-off HEMT is proposed: it uses for the first time the implantation of Fluorine ions in the GaN layer below the AlGaN/GaN interface rather than in the AlGaN layer. Simulation results show that the proposed method is more effective when it comes to the Fluorine concentration required to achieve normally-off operation.

Scalable normally-off MIS-HEMT using fluorine implantation below the channel

A new normally-off Metal-Insulator-Semiconductor High-Electron-Mobility-Transistor (MIS-HEMT) is proposed. The design is based on the implantation of fluorine ions in the GaN layer below the gate electrode under the AlGaN/GaN interface. Sensitivity analyses are carried out, showing the effects of the fluorine concentration and the thickness of the insulator on the threshold voltage. The limitations and scalability of this technique are pointed out.

Comparison of Electrical Behavior of GaN-Based MOS Structures Obtained by Different PECVD Process

MOS SiO2/GaN structures were fabricated with different surface preparation and different PECVD processes for the dielectric thin film deposition (ECR-PECVD and ICP-PECVD in continuous and pulsed modes). On the basis of C-V curves, the surface preparation steps, involving chemical etching with BOE, UV-Ozone oxidation and oxygen plasma oxidation, were compared in terms of resulting effective charge and interface trap density. A good SiO2/GaN interface quality was achieved for N-type MOS capacitances obtained both with continuousICPPECVD and ECR-PECVD deposition of the SiO2 dielectric. However, the interface quality is greatly reduced for MOS capacitors fabricated on P-type GaN.

Conception de transistors MOS haute tension (1 200 volts) pour l'électronique de puissance

In this work, we have studied many concepts to design a new MOSFET structure. We have chosen a superjunction based structure made by deep etching and boron diffusion. The main part of the work was to optimize this structure. For this, we have studied many technological parameters influence on the Breakdown voltage/On-state resistance trade-off. We have developed a new innovated junction termination in order to sustain the desired breakdown voltage. It was necessary to identify the process critical steps. From this point, we have fabricated a 1200 V diode which enabled to validate some of these steps but also the original termination.