Abstract: A gate oxide layer for a high voltage transistor is formed using methods that avoid thinning in the corners of the gate oxide layer. A recess is formed in a silicon substrate. The exposed surfaces of the recess are thermally oxidized to form a thermal oxide layer of the gate oxide layer. A high temperature oxide layer of the gate oxide layer is then formed within the exposed surfaces of the recess by chemical vapor deposition. The combination of the thermal oxide layer and the high temperature oxide layer results in a gate oxide layer that does not exhibit the double hump phenomenon in the drain current vs. gate voltage curve. The high temperature oxide layer may include a rim that extends out of the recess.

Abstract: A folding frame includes an upper body, a lower body, a fixing device disposed on the upper body, a hook rotatably coupled to the lower body, and a fastener for rotating the hook opposite to the lower body. The fastener comprises a shaft of which a first end is coupled to the hook, a spring of which a first end is coupled to a second end of the shaft, and a latch pin capable of moving the spring thereby moving the shaft for rotating the hook, and of which a first end of the latch pin is coupled to a second end of the spring. The hook is unhooked from the fixing device when the hook is rotated into the lower body, and the hook is engaged with the fixing device when the hook is rotated out from the lower body.

Abstract: A folding frame includes an upper body, a lower body, a fixing device disposed on the upper body, a hook rotatably coupled to the lower body, and a fastener for rotating the hook opposite to the lower body. The fastener comprises a shaft of which a first end is coupled to the hook, a spring of which a first end is coupled to a second end of the shaft, and a latch pin capable of moving the spring thereby moving the shaft for rotating the hook, and of which a first end of the latch pin is coupled to a second end of the spring. The hook is unhooked from the fixing device when the hook is rotated into the lower body, and the hook is engaged with the fixing device when the hook is rotated out from the lower body.