Abstract: A lowest-layer insulating film and at least one upper-layer insulating film are used. The etching rate for the lowest-layer insulating film changes in response to change in flow rate of a predetermined etching reactive gas. The etching rate for the at least one upper-layer insulating film under the condition in which the flow rate of the etching reactive gas is a first flow rate such that the etching rate for the lowest-layer insulating film is low is higher than the etching rate for the lowest-layer insulating film under the condition in which the flow rate of the etching reactive gas is the first flow rate. First etching is performed under the condition in which the flow rate of the etching reactive gas is the first flow rate. Then, second etching is performed under the condition in which the flow rate of the etching reactive gas is a second flow rate such that the etching rate for the lowest-layer insulating film is high.

Abstract: An air-fuel ratio control system for a gas-fueled engine which is capable of achieving the combustion in a target air-fuel ratio to surely purify an exhaust gas through an exhaust purification catalyst. In the air-fuel ratio control system, a three-way catalytic converter is placed in an exhaust pipe of the engine and an O2 sensor is located on the upstream side of the three-way catalytic converter. The O2 sensor comprises an element, and an atmosphere side electrode is formed on an inner surface of the element while an exhaust gas side electrode is formed on an outer surface thereof. The exhaust gas side electrode is coated with a catalyst layer which can remove hydrogen through a catalytic reaction. A control unit of the control system controls a fuel supply quantity by a gas injector using a feedback correction coefficient on the basis of the output of the O2 sensor, thereby reducing the deviation between an air-fuel ratio measured by the O2 sensor and a target air-fuel ratio.

Abstract: A semiconductor device having a multilayer interconnection structure, includes a substrate having a metal interconnect layer provided thereon and N number (N being an integer of 2 or greater) of layers of insulating film formed one on top of another on the substrate. Each layer of insulating film has a metal interconnect layer including at least one bonding pad section provided thereon. At least one via hole filled with an electrically conductive material is provided in each of the layers for interconnecting metal interconnect layers. At least one bonding pad connecting hole filled with an electrically conductive material is provided in each of the layers for interconnecting bonding pad sections. The at least one bonding pad connecting hole is no more than twice as large in diameter as a smallest via hole.