Abstract: An epitaxial growth layer, an oxide film, and a passivation film are formed on a silicon substrate. Except for an opening formed on a part of the passivation film, the upper surface of the passivation film is covered with a metal protective film made of tungsten (W). With the silicon substrate immersed in a high-concentration hydrofluoric aqueous solution, anodization is performed with the silicon substrate as an anode and the metal protective film as a counter electrode.

Abstract: An acceleration switch that improves detection sensitivity without being enlarged. The acceleration switch includes a switch body, a fixed electrode arranged in the switch body, and a movable weight arranged in the switch body. The movable weight is displaced when subjected to acceleration. The movable weight includes a movable electrode that contacts the fixed electrode when the movable weight is displaced, and a pair of beams connecting the movable weight and the switch body. The beams pivotally support the movable weight and extend into recesses formed in the movable weight.

Abstract: A method for anodizing silicon substrate includes forming an n-type silicon embedded layer (21) made of n-type silicon on a predetermined area of a first surface of the p-type single crystal silicon substrate (2). N-type silicon layers (4, 6) are formed on the upper surface of the p-type single crystal silicon substrate (2) and on the n-type silicon embedded layer (21). Silicon diffusion layers (5, 7) containing high-concentration p-type impurities are formed on predetermined areas of the n-type silicon layers (4, 6) to contact the n-type silicon embedded layer (21). An electrode layer (13) is formed on the lower surface of the p-type silicon substrate (2). The anode of a DC power source (15) is connected to the electrode layer (13), and the cathode is connected to a counter electrode (23), which is opposed to the p-type silicon substrate (2).

Abstract: A first p-type silicon layer (3) is formed as a buried layer in a p-type single crystal silicon substrate (2), and an n-type silicon layer (4) is formed on the upper side of the silicon substrate (2). A second p-type silicon layer (5) for forming an opening is defined in the n-type silicon layer (4), and a metal protecting film (14) is formed on the upper side of the n-type silicon layer (4). An electrode layer (18) is formed on the rear side of the silicon substrate (2) via an oxide film (17). The electrode layer (18) and the silicon substrate (2) are electrically connected to each other via a connecting opening (17a) at portions aligned with the first p-type silicon layer (3). After a positive terminal and a negative terminal of a DC power source (V) are connected to the electrode layer (18) and to a counter electrode (11) respectively, a voltage is applied between the electrode layer (18) and the counter electrode (11) to carry out anodization.

Abstract: A small acceleration switch adapted to switch between ON and OFF states depending upon the magnitude of acceleration applied to the switch. The acceleration switch includes a first contact formed on a substrate and a movable part formed on a semiconductor chip by surface micromachining. The movable part includes a second contact. When the acceleration is equal to or greater than a predetermined value, the movable part moves and the second contact comes into contact with the first contact.

Abstract: An acceleration switch that improves detection sensitivity without being enlarged. The acceleration switch includes a switch body, a fixed electrode arranged in the switch body, and a movable weight arranged in the switch body. The movable weight is displaced when subjected to acceleration. The movable weight includes a movable electrode that contacts the fixed electrode when the movable weight is displaced, and a pair of beams connecting the movable weight and the switch body. The beams pivotally support the movable weight and extend into recesses formed in the movable weight.

Abstract: A surface type acceleration sensor includes a p-type single crystal silicon base plate, a cantilever functioning as a cantilever structure portion, and a plurality of strain gauges. The cantilever is disposed in a recess portion formed on the front face of the p-type single crystal silicon base plate so that the cantilever can be displaced in the upward and downward direction. The cantilever includes an epitaxial growth layer principally made of n-type single crystal silicon. The strain gauge is made of p-type silicon and formed on an upper face of the base end portion of the cantilever.

Abstract: A surface type acceleration sensor includes a p-type single crystal silicon base plate, a cantilever functioning as a cantilever structure portion, and a plurality of strain gauges. The cantilever is disposed in a recess portion formed on the front face of the p-type single crystal silicon base plate so that the cantilever can be displaced in the upward and downward direction. The cantilever includes an epitaxial growth layer principally made of n-type single crystal silicon. The strain gauge is made of p-type silicon and formed on an upper face of the base end portion of the cantilever.