Abstract: A semiconductor device includes a substrate which includes a first face. The device also includes a buffer layer, a semiconductor layer, source and drain electrodes, and a gate electrode. A trench is formed on the semiconductor layer so that the trench surrounds the source electrode, the drain electrode, and the gate electrode in a plan view, the trench passes through the semiconductor layer and the buffer layer, and a bottom of the trench reaches at least an inside of the substrate. A distance from the first face of the substrate to the bottom of the trench is 100 nm or more in a thickness direction of the substrate.

Abstract: Sometimes to warp a group III nitride semiconductor and a silicon by the stress of the group III nitride semiconductor acting on the silicon. A semiconductor device includes a substrate, a buffer layer, and a semiconductor layer. A trench is formed on a sixth face of the semiconductor layer. The trench passes through the semiconductor layer and the buffer layer. The bottom of the trench reaches at least the inside of the substrate.

Abstract: Sometimes to warp a group III nitride semiconductor and a silicon by the stress of the group III nitride semiconductor acting on the silicon. A semiconductor device includes a substrate, a buffer layer, and a semiconductor layer. A trench is formed on a sixth face of the semiconductor layer. The trench passes through the semiconductor layer and the buffer layer. The bottom of the trench reaches at least the inside of the substrate.

Abstract: The cleaning treatment apparatus of the present invention is constituted so that a cleaning liquid is continuously supplied by a liquid film forming means in a gap formed between a surface of a processed member held horizontally and rotationally driven by a holding and rotating means and a ultrasonically oscillating lower face of a ultrasonic oscillating means, to thereby form a liquid film in the gap. Hereby, the surface of the processed member is subjected to a cleaning treatment by the liquid film, which is ultrasonically oscillated by the ultrasonic oscillating means. At this stage, as the processed member is rotated by the holding and rotating means, the surface of the processed member is properly cleaned by the ultrasonically oscillating cleaning liquid not only in a region thereof opposed to the ultrasonic oscillating means during the standstill of the member but also in a region thereof opposed to the ultrasonic oscillating means during the rotation of the member.