Mobility enhancement by mechanical uniaxial stress on 4H-SiC (0001) lateral metal-oxide-semiconductor field-effect-transistor

Abstract

We investigated the impact of the mechanical uniaxial strain on the inversion channel mobility of lateral n-channel metal-oxide-semiconductor field-effect transistor (MOSFET) on 4H-SiC(0001). We used custom-designed bend-holders to apply a tensile and compressive stress to the chip after MOSFET fabrication. The behavior of mobility with the two different channel directions and was investigated on the bend directions and with the tensile and compressive stress. We found that the inversion channel mobility effectively increases with the uniaxial compressive stress of the perpendicular configuration which is the drain current flow perpendicular to the bend direction. From the temperature dependence of mobility, we deduced that the enhancement of mobility is attributed to the reduction of the effective mass in 4H-SiC by introduced stress.

Stress Engineering for Drive Current Enhancement in Silicon Carbide (SiC) Power MOSFETs

“…It has also been predicted theoretically that stress can improve the mobility for SiC [24], [25]. Further, there is experimental literature showing improved mobility with externally applied strain in SiC planar MOSFETs [26], [27]. However, the kind of strain inducing enhancements that are standard in Si CMOS have not been integrated into SiC transistor structures so far.…”

Comparative study of mechanical stress-induced flat-band voltage change in MOS capacitor and threshold voltage change in MOSFET fabricated on 4H-SiC (0001)

“…It needs to be noted that the uniaxial strain induced by this bending method is not the same kind as the expected strain in mass production devices; however, this method has its own advantage for excluding other variables and showing stress' solo impact on the device. 15) In this study, we will describe a quantitative relationship between uniaxial stress and device performance, focusing on field-effect mobility (μ FE ) and V th , and discuss the origins of the variability of device performance with stress.…”

“…The channel direction was along. [11][12][13][14][15][16][17][18][19][20] The MOS interface was passivated by a conventional nitridation process with nitric oxide (NO) gas after the growth of 38 nm thick oxide. A Si (100) n-MOSFET with 8 nm thick oxide and channel along [110] was used for electrical characteristics comparison and stress evaluation based on a clear relationship between the ratio of the change in peak field-effect mobility ( FE m D ) and applied stress established on Si n-MOSFETs.…”

The effect of biaxial strain on the phonon-limited mobility in 4H-SiC MOSFETs

“…They have reported that compressive stress improves mobility due to lighter effective mass. 23,24) However, the tensile stress on 4H-SiC has not received much attention.…”

“…Here, we limit the discussion on the strain below 0.5% since experiments have reported sub-GPa stress in SiC interface. 21,23) The first and second conduction band minima for 4H-SiC are located at point M of the Brillouin zone. Although the biaxial stress was applied, the crystal symmetry in the (0001)plane did not change when the surface was in the c plane [(0001) plane].…”