Nippondenso Co., Ltd.

Toshiaki Nishizawa

Akira Kuroyanagi

Norihito Tokura

Tsuyoshi Yamamoto

Yasuaki Tsuzuki

Yukihisa Takeuchi

Kenji Maekawa

Masaaki Mori

A power semiconductor device having a current detecting function comprising a detection part that includes the elements of a better reach-through withstand voltage capability than those of a principal current part. The power semiconductor device comprises such elements as DMOS, IGBT or BPT cells. One area of the device acts as the detection part and another as the principal current part. The detection part and the principal current part share as their common electrode a high density substrate having a low density layer of a first conductivity type. The surface of the low density layer carries a principal and a subordinate well region of a second conductivity type each. The surface of the principal well region bears a surface electrode region of the first conductivity type acting as the other electrode of the principal current part; the surface of the subordinate well region carries a surface electrode region of the first conductivity type acting as the other electrode of the detection part. The subordinate well region is made shallower than the principal well region illustratively by use of a mask having narrower apertures through which to form the former region. This causes a reach-through to occur in the principal current part with its well region having a shorter distance to the high density substrate, and not in the detection part with its well region having a longer distance to the substrate.

Semiconductor device with current detecting function and method of

A power DMOS semiconductor device is producible with standard processes and provides improved current detecting accuracy. The device involves main wells (41), subwells (42), and a line well (43), which is independent of the main wells and subwells. These wells are formed by doping the surface of a semiconductor substrate (1) with well forming impurities. The line well surrounds the subwells with a predetermined distance away from the subwells, to relax an electric field on the surface of the substrate. Gate electrodes (71, 72) are patterned to form a line opening (10), which surrounds the subwells. The line opening serves as a mask when forming the line well by doping the surface of the substrate with the well forming impurities. Accordingly, the width of a region between the line well and an adjacent subwell will not fluctuate.

Method of producing a semiconductor device having accurate current

A power semiconductor device having current detecting function comprising a detection pert that includes the elements of a better reach-through withstand voltage capability than those of a principal current part. The power semiconductor device comprises such elements as DMOS, IGBT or BPT cells. One area of the device acts as the detection part and another as the principal current part. The detection part and the principal current part share as their common electrode a high density substrate having a low density layer of a first conductivity type. The surface of the low density layer carries a principal and a subordinate well region of a second conductivity type each. The surface of the principal well region bears a surface electrode region of the first conductivity type acting as the other electrode of the principal current part; the surface of the subordinate well region carries a surface electrode region of the first conductivity type acting as the other electrode of the detection part. The subordinate well region is made shallower than the principal well region illustratively by use of a mask having narrower apertures through which to form the former region. This causes a reach-through to occur in the principal current part with its well region having a shorter distance to the high density substrate, and not in the detection part with its well region having a longer distance to the substrate.

Method of producing semiconductor device with current detecting function

A power DMOS semiconductor device providing improved current detection accuracy can be produced using standard pocessess. The device includes main wells, subwells and a line well which is independent of the main wells and subwells. These wells are formed by doping the surface of a semiconductor substrate with well-forming impurities. The line well surrounds the subwells at a predetermined distance away from the subwells to relax an electric field on the surface of the substrate. Gate electrodes are patterned to form a line opening which surrounds the subwells. The line opening serves as a mask when forming the line well by doping the surface of the substrate with the well-forming impurities. Accordingly, the width of a region between the line well and an adjacent subwell will not fluctuate.

Vertical type semiconductor with main current section and emulation

A flexible amorphous silicon solar battery comprising a metal foil as the substrate thereof, an insulating layer integrally formed on the metal foil, and at least one amorphous silicon photoelectric conversion portion formed on the insulating layer. The amorphous silicon photoelectric conversion portion thereof comprises an a-Si thin film having a potential barrier therein, an upper electrode and a lower electrode. The a-Si thin film is sandwiched between the upper and lower electrodes. The upper electrodes may be formed of a transparent conductive film. The transparent conductive film may be also in two layers composed of a relatively thin tin dioxide film and a relatively thick ITO film thereby to lower the resistance of transparent conductive film and to obtain a superior a-Si thin film having no impurity particles therein. A plurality of a-Si photoelectric conversion portions may be formed on the same substrate, and are connected in series with one another, to increase the output voltage thereof. The a-Si photoelectric conversion portions may be formed as forward junction and/or reverse junction types. The a-Si solar battery of this invention is flexible because of use of a metal foil with thickness of 10 to 250 .mu.m such as stainless steel, aluminum or iron as the substrate thereof, so that it can be easily attached to a product having a curved surface thereon, such as an automobile or the like. Further, there are no problems or disadvantages, such as spallings and cracks of the a-Si thin film, or deterioration of the physical properties thereof, so that the a-Si solar battery of this invention can provide excellent conversion efficiency.

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Obu, Japan

Toshiaki Nishizawa