Hall element for detecting a magnetic field perpendicular to a substrate

Abstract: In a Hall element, a semiconductor layer (13) is surrounded by a first trench (14) filled with an insulator. A first current supply portion (16) of an n+-type semiconductor is disposed adjacent the semiconductor layer (13) and the first trench (14). Second current supply portions (17,17') are also disposed adjacent the semiconductor layer (13) and the first trench (14) and symmetrical with respect to the first current supply portion (16). Sensor portions (18,18') of an n+-type semiconductor are disposed adjacent the semiconductor layer and the first trench at about the center between the first and second current supply portions (16,17,17') respectively. A magnetic flux perpendicular to the upper surface of the semiconductor layer (13) can be detected by the foregoing arrangement.

Description: The present invention relates to a Hall element for detecting a magnetic field. More particularly, the present invention relates to a planar Hall element having electrodes formed on a surface of the device and being capable of detecting a magnetic field in a direction perpendicular to that surface. A Hall element can be used as a magnetic field sensor. Since current causes a magnetic field, a Hall element can also be used as a current detector, which, for example, might be applied in an electricity counter. Fig. 1 is a view of a Hall element. In the Hall element, current supply electrodes C1 and C2 are positioned on opposite sides of a semiconductor substrate 1. Sensor electrodes S1 and S2 are positioned on the other opposite sides. A magnetic field is applied in a direction perpendicular to Fig. 1 (i.e., into the paper on which Fig. 1 is printed, as is represented by arrow B). When a current flows between current supply electrodes C1 and C2 with a magnetic flux, an electromotive force, i.e., a Hall voltage, occurs between sensor electrodes S1 and S2. Assuming that the current has a current density J, and the magnetic flux has a magnetic flux density B, and further assuming that an x-axis exists in the direction from current supply electrode C1 to current supply electrode C2, a y-axis exists in the direction from sensor electrode S1 to sensor electrode S2, and a z-axis exists in the direction from the back to the front of Fig. 1, the equation E y = R H x J x x B z will be satisfied, where E y is a y-axis component of an electric field, J x is an x-axis component of current density J, B z is a z-axis component of magnetic flux density B, and R H is a Hall coefficient. In the Hall element of Fig. 1, L represents the distance between current supply electrodes C1 and C2, and W represents the distance between sensor electrodes S1 and S2. The rate of L/W must be large to obtain a large Hall voltage. U.S. Patent Nos. 4,782,375 and 4,987,467 disclose Hall elements whose electrodes C1, C2, S1 and S2 are situated on a surface of a semiconductor substrate 1, i.e., a planar type semiconductor device. Fig. 2 shows a typical Hall element of the type disclosed in the aforementioned patents. In Fig. 2, current supply electrode C1 is positioned at a central location between current supply electrodes C2. Sensor electrodes S1 and S2 are positioned between current supply electrodes C1 and C2. Since a current I between current supply electrodes C1 and C2 has a current component perpendicular to substrate 1, the Hall element of Fig. 2 detects a magnetic field parallel to the surface of substrate 1. The dimensions L and W from Fig. 1 are also shown in Fig. 2. In Fig. 2, W substantially corresponds to the width of current supply electrode C1, and L substantially corresponds to the distance between current supply electrodes C1 and C2. The Hall element shown in Fig. 2 requires a large current component perpendicular to substrate 1. Therefore, the width of current supply electrode C1 must be large which, in turn, increases the size of W. This means that L must also be large to ensure that L/W will remain satisfactorily large. The overall result is that the size of the Hall element shown in Fig. 2 is large. An offset voltage, which would exist without any magnetic field, is another problem. An offset voltage is sometimes caused by the asymmetrical placement of electrodes C2, S1, S2 with respect to electrode C1. Also, an offset voltage is sometimes caused by stress, since the mobilities of carriers may change due to the piezo effect and, also, the amount of piezo effect is different depending upon the crystal direction. For example, piezoresistances change at a 90° period in the <100> plane of silicon (Si). The current shown in Fig. 2 has a component flowing close to the surface of substrate 1. Since stress is large at that surface, the offset voltage problem still remains. A Hall element may be positioned within a gap in a yoke wound by a wire carrying an object current to detect a magnetic field. This gap must be narrow, because a magnetic field applied to a Hall element is in inverse proportion to the distance of the gap. However, since the magnetic field direction in the Hall element shown in Fig. 2 is parallel with respect to the substrate, the gap will be unavoidably large in the case where such a Hall element is inserted in the gap. As can be understood from the above, the sensitivity of a current detector using a planar type Hall element is not sufficient. SUMMARY OF THE INVENTION Accordingly, one object of this invention is to provide a Hall element which is a planar type semiconductor device that can detect a magnetic field perpendicular to a substrate. Another object of this invention is to provide a Hall element with a reduced offset voltage. Accordingly the present invention provides a Hall element comprising a semi-conductor layer comprising at least one rectangular region of a first conductivity type; a first current supply portion of the first conductivity type disposed in the semi-conductor layer, and a pair of second current supply portions of the first conductivity type disposed in the semi-conductor layer so that the first current supply portion is between them; a pair of sensor portions of the first conductivity type which are also disposed in the semi-conductor layer between the second current supply portions so that the first current supply portion is between the sensor portions; characterised by a peripheral insulator portion extending around the sides of the rectangular region, the current supply portions and the sensor portions all being arranged so as to contact the insulator portion; whereby a Hall voltage is induced between the sensor portions in the presence of a magnetic flux perpendicular to the upper surface of the semi-conductor layer during current flow between the first current supply portion and second current supply portions along a current path through the semi-conductor layer. The Hall element according to the present invention can be applied to a current detector comprising a magnetic yoke having a gap within which the Hall element of the present invention is disposed, with a wire carrying an object current and winding around the magnetic yoke. The semiconductor layer may provide an insulator layer on a bottom surface, which the insulator portion preferably reaches. Also, the first and second current supply portions and sensor portions preferably reach the insulator layer. A Hall element according to the present invention may provide a gate insulator layer disposed on the surface of the semiconductor layer; and a gate electrode disposed on the gate insulator layer, so that current can flow away from the surface by forming a depletion layer, an accumulation layer, or an inversion layer under the gate insulator layer. Also, a Hall element according to the present invention may provide a second conductivity type semiconductor layer disposed on the semiconductor layer for the same effect. Further, a Hall element according to the present invention may provide a current path control means, e.g., a second type semiconductor layer or an insulated gate electrode, to increase the length of the current path between the first and second current supply portions. In the present invention, the semiconductor layer may be formed on a substrate having an insulator surface, e.g., SOI (silicon on insulator), or may be formed on a semiconductor substrate of a second conductivity type. The SOI is effective to reduce the effect of substrate electric potential to a Hall voltage. The semiconductor layer preferably has a thickness of from about 5 µm to about 10 µm, and a carrier concentration of from about 10 15 cm -3 to about 10 16 cm -3 , so as to obtain high sensitivity. Additional objects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed. BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the objects, advantages, and principles of the invention. In the drawings: Fig. 1 is a view of a Hall element; Fig. 2 is a sectional view of a conventional Hall element; Fig. 3(a) is a plan view of a Hall element in accordance with an embodiment of the present invention; Figs. 3(b) and 3(c) are sectional views of the Hall element depicted in Fig. 3(a); Fig. 4 is a view of a current detector including a Hall element; Fig. 5 is a graph showing a V in -V H relation; Fig. 6(a) is a plan view of a Hall element in accordance with another embodiment of the present invention; Fig. 6(b) is a sectional view of the Hall element depicted in Fig. 6(a); Fig. 7(a) is a plan view of a all element in accordance with yet another embodiment of the present invention; Figs. 7(b) and 7(c) are sectional views of the Hall element depicted in Fig. 7(a); Fig. 8(a) is a plan view of a Hall element in accordance with still another embodiment of the present invention; Fig. 8(b) is a sectional view of the Hall element depicted in Fig. 8(a); Fig. 9(a) is a plan view of a Hall element in accordance with yet another embodiment of the present invention; Fig 9(b) is a sectional view of the Hall element depicted in Fig. 9(a); Fig. 10(a) is a plan view of a Hall element in accordance with still another embodiment of the present invention; and Fig. 10(b) is a sectional view of the Hall element depicted in Fig. 10(a). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Example 1 Fig. 3(a) is a plan view of a Hall element in accordance with an embodiment of the present invention. Fig. 3(b) is a sectional view taken along line a-a' of Fig. 3(a), and Fig. 3(c) is a sectional view taken along line b-b' of Fig. 3(a). With reference to Figs. 3(a), 3(b), and 3(c), a semiconductor layer 13 of a first semiconductor type (an n-type semiconductor, for example) is formed on an insulator layer 12 disposed on a semiconductor substrate 11. For example, an SOI (silicon on insulator) substrate can be used. Semiconductor layer 13 is surrounded by a first trench 14 filled with an insulator to form an insulator portion. As best seen from Fig. 3(a), portions of semiconductor layer 13 intermittently abut the inside surface of the leftward wall of first trench 14. A first current supply portion 16 of an n+-type semiconductor (e.g., at least 10 19 cm -3 ) is disposed between two of the intermittently abutting portions of semiconductor layer 13 and in contact with the inside surface of the leftward wall of first trench 14. First current supply portion 16 extends down to insulator layer 12. Second current supply portions 17, 17' are disposed between two of the intermittently abutting portions of semiconductor layer 13 and in contact with the inside surface of the leftward wall of first trench 14. Each second current supply portion 17, 17' is located so as to be symmetrical with respect to first current supply portion 16. In other words, first and second current supply portions 16, 17, 17', are arranged in a line and first current supply portion 16 is placed at the center between second current supply portions 17, 17'. Second current supply portions 17, 17' also reach insulator layer 12. Further, sensor portions 18, 18' of an n+-type semiconductor (e.g., at least 10 19 cm -3 ) are disposed between two of the intermittently abutting portions of semiconductor layer 13 and in contact with the inside surface of the leftward wall of first trench 14. Sensor portions 18, 18' are positioned at or near the center between first and second current supply portions 16, 17, and 17'. Sensor portions 18, 18' also reach insulator layer 12. Further, current path control portions 19 of a second semiconductor type (a p-type semiconductor of at least 10 17 cm -3 , for example) are disposed between two of the intermittently abutting portions of semiconductor layer 13 and in contact with the inside surface of the leftward wall of first trench 14. Current path control portions 19 are positioned between first current supply portion 16 and sensor portions 18, 18', and between second current portions 17, 17' and sensor portions 18, 18', respectively. Current path control portions 19 also reach insulator layer 12. The upper surface of semiconductor layer 13 is covered with a second insulator layer 20 having a thickness, for example, of hundreds of angstroms 1 angstrom = 0.1 nm. Second insulator layer 20, in turn, is covered with a gate electrode 21. Second insulator layer 20 and gate electrode 21 are shown in Figs. 3(b) and 3(c), but not in Fig. 3(a). As can be understood from Figs. 3(a), 3(b), and 3(c), and from the description above, first and second current supply portions 16, 17, 17', sensor portions 18, 18', and current path control portions 19 are arranged in a line along first trench 14. Second insulator layer 20 has holes corresponding to first current supply portions 16, second current supply portions 17, 17', sensor portions 18, 18', and current path control portions 19. An electrode is formed in each of the holes. The Hall element in the embodiment of Figs. 3(a), 3(b), and 3(c) may be produced using ordinary planar techniques designed for integrated circuits, e.g., diffusion, etching, deposition, oxidation, and the like. In the embodiment of Figs. 3(a), 3(b) and 3(c), since first and second current supply portions 16, 17, 17' are adjacent to first trench 14, a current I between first and second current supply portions 16, 17, 17' has a current component perpendicular to a plane corresponding to the inside surface of the leftward wall of first trench 14. Further, the current I between first and second current supply portions 16, 17, 17' is asymmetrical with respect to that plane causing magnetic flux perpendicular with respect to the upper surface of semiconductor layer 13. As a result, magnetic flux perpendicular to the upper surface of semiconductor layer 13 can be detected, i.e., when magnetic flux B is applied in a direction perpendicular with respect to a plane of semiconductor layer 13 (the plane including the upper surface of semiconductor layer 13, for example), a Hall voltage is induced between sensor portions 18, 18'. If first trench 14 were not provided, current I would flow symmetrically on both sides of the line in which first and second current supply portions 16, 17, 17' are arranged. Consequently, the Hall voltage due to the current on the left side of the line would counterbalance the Hall voltage due to the current on the right side of the line. As a result, if first trench 14 were not provided, a Hall voltage would not be induced by a magnetic field perpendicular to the upper surface of semiconductor layer 13. In accordance with the embodiment depicted in Figs. 3(a), 3(b), and 3(c), the current I between first and second current supply portions 16, 17, 17' must be asymmetrical with respect to the plane corresponding to the line in which current supply portions 16, 17, 17' are arranged, with magnetic flux perpendicular with respect to the upper surface of semiconductor layer 13. Therefore, it is not necessarily required that portions 16, 17, 17' must contact first trench 14. However, since the Hall voltage would become smaller with an increase in distance between portions 16, 17, 17' and first trench 14, portions 16, 17, 17' are preferably disposed in contact with first trench 14 in the manner depicted in Figs. 3(a), 3(b), and 3(c). Since the position of sensor portions 18, 18' can be arranged so as to detect a Hall voltage, it is not necessary for these portions to be adjacent to first trench 14 and at a central position between first and second current supply portions 16, 17, 17'. However, if the distance between first current supply portion 16 and sensor portion 18 is different from the distance between first current supply portion 16 and sensor portion 18', an offset voltage may exist. Further, when sensor portions 18, 18' are placed near the center between first and second current supply portions 16, 17, 17', the Hall voltage is at a maximum. Therefore, sensor portions 18, 18' are also preferably arranged in contact with first trench 14 in the manner depicted in Figs. 3(a), 3(b), and 3(c). Fig. 4 is a view of a current detector. The current detector comprises a yoke 41 of ferromagnetic material, e.g., Fe, FeNi alloys, ferrite or the like, having a gap 42. A wire 43 carrying an object current I is wound around yoke 41. A Hall element 44 is placed in gap 42 so as to detect a magnetic field. If a Hall element in accordance with the present invention is used as Hall element 44, gap distance t can be almost the same as the thickness of the Hall element, i.e., gap distance t could be reduced in size. Therefore, since a magnetic field due to current I is formed in gap 42 in inverse proportion to gap distance t, a current detector having a good sensitivity can be provided by using a Hall element in accordance with the present invention as Hall element 44. The Hall element of the present invention is also effective for increasing a current component parallel to the upper surface of semiconductor layer 13 (see the embodiment of Figs. 3(a), 3(b), and 3(c)) given that first and second current supply portions 16, 17, 17' reach first insulator layer 12. Further, in this embodiment, current I can flow away from the upper surface of semiconductor layer 13, when a bias voltage is applied to gate electrode 21, so as to make a depletion layer at the upper surface of semiconductor layer 13. As a result, any offset voltage which may result from a piezo effect is reduced. The same thing is true if current flowing away from the upper surface of semiconductor layer 13 causes an inversion layer at the upper surface. An inversion layer under the gate insulator layer 20 is just as or nearly as effective as the aforementioned depletion layer, which depends on carriers, i.e., electrons or holes. Also, in accordance with the present invention, current I can flow away from first trench 14, when a reverse bias voltage is applied to current path control portions 19, so as to make a depletion layer around current path control portions 19. This changes the length of the current path between first and second current supply portions 16, 17, 17'. In the embodiment of Fig. 3(a), W substantially corresponds to the width of first current supply portion 16, and L substantially corresponds to the distance between first and second current supply portions 16, 17, 17'. Therefore, since the current path can be lengthened by only applying a reverse bias voltage to current path control portions 19, the ratio of L/W can be enlarged without enlarging the distance between first and second current supply portions 16, 17, 17'. Also, an insulated trench gate electrode could replace current path control portions 19. If a bias voltage is applied to this insulated trench gate electrode, so as to form a depletion layer in semiconductor layer 13 around this insulated trench gate electrode, this also can lengthen the current path. Substrate 11 may be an n-type or p-type semiconductor in view of the provision of insulator layer 12. Further, if substrate 11 is an insulator, insulator layer 12 is not required. Also, semiconductor layer 13 of the first conductivity type, i.e., n-type, could be disposed directly on substrate 11 of the second conductivity type, i.e., p-type. However, substrate 11 providing an insulator surface, i.e., SOI structure, is preferable, since this would reduce the effect of the electric potential of substrate 11. Further, a similar effect would be achieved due to gate electrode 21 if semiconductor layer 13 provides a p-type semiconductor layer at a surface as a replacement for gate electrode 21 and second insulator layer 20. In other words, a p-type layer could be used to replace the structure including gate electrode 21 and second insulator 20. Fig. 5 shows a graph of a relation between V in and V H at B = 1000G. A continuous line shows a device using SOI, wherein the semiconductor layer has a thickness of 5 µm and Nd of 2 x 10 15 cm -3 , and the thickness of the insulator layer 12 is 0.5 µm. A broken line shows a device using pn isolation without SOI. According to Fig. 5, the device with the SOI structure has good linearity. Example 2 This embodiment of the invention, depicted in Figs. 6(a) and 6(b), is a variation of the embodiment discussed above in Example 1. Fig. 6(a) is a plan view of a Hall element in accordance with another embodiment of the present invention. Fig. 6(b) is a sectional view of that Hall element taken along line a-a' of Fig. 6(a). While the embodiment of Example 1 provides one set of first and second current supply portions 16, 17, 17' and sensor portions 18, 18' on one side of semiconductor layer 13 (i.e., at the left side of semiconductor layer 13), the embodiment of Example 2 provides two sets of these portions 16, 17, 17', 18, 18' on two opposing sides facing one another. Also, in the embodiment of Example 2, current path control portions 19 are only placed between sensor portions and second current supply portions 18, 18', 17, 17'. However, current path control portions 19 could be placed between sensor portions and first current supply portions 18, 18', 16. The other details of the embodiment of Example 2 are the same as in the embodiment of Example 1. When one set of portions 16, 17, 17', 18, 18' is provided in the manner shown in Fig. 3(a), an offset voltage may exist, if the placement of second current supply portions 17, 17' and sensor portions 18, 18' is such that these portions are not symmetrical with respect to the position of first current supply portion 16. However, since the embodiment in Example 2 provides two sets of portions 16, 17, 17', 18, 18' on opposing sides of semiconductor layer 13, any offset voltage that may have resulted from the placement of portions 16, 17, 17', 18, 18' is reduced. In the embodiment of Example 2, detected Hall voltages can be used to cancel occurrences of offset voltage. In this regard, since a Hall voltage at one side of the semiconductor layer 13 is opposite that at the other side of semiconductor layer 13, any occurrences of offset voltage may be counterbalanced with each other. As a result, any offset voltage due to inaccurate mask placement during production of these portions 16, 17, 17', 18, 18', which is unavoidable, is reduced more than in Example 1. For example, when sensor portion 18 on one side of semiconductor layer 13 is connected to sensor portion 18' on the other side of semiconductor layer 13, an average Hall voltage between sensor portion 18' on the one side and sensor portion 18 on the other side would have a reduced offset voltage relative to that resulting from the structure found in Example 1. Example 3 This embodiment of the invention, depicted in Figs. 7(a), 7(b), and 7(c), is also a variation of the embodiment discussed above in Example 1. Fig. 7(a) is a plan view of a Hall element in accordance with yet another embodiment of the present invention. Fig. 7(b) is a sectional view taken along line a-a' of Fig. 7(a), and Fig. 7(c) is a sectional view taken along line b-b' of Fig. 7(a). In Example 3, semiconductor layer 13 is divided into a first region 13, and a second region 13 2 by a second trench 15 filled with an insulator and located in a central portion of semiconductor layer 13. In each of first and second regions 13 1 and 13 2 , first current supply portion 16, second current supply portions 17, 17', sensor portions 18, 18', and current path control portions 19, are formed adjacent to second trench 15 so as to be symmetrical with respect to second trench 15. The other details of the embodiment of Example 3 are the same as in the embodiment of Example 1. Even if the locations of sensor portions 18, 18' and second current supply portions 17, 17' are not completely symmetrical with respect to first current supply portion 16, any offset voltage of first region 13 1 would be opposite to any offset voltage of second region 13 2 , with the result being that such offset voltages could counterbalance each other. Example 4 Fig. 8(a) is a plan view of a Hall element in accordance with still another embodiment of the present invention. Fig. 8(b) is a sectional view taken along line b-b' of Fig. 8(a). The embodiment of Example 4 provides two sets of portions 16, 17, 17', 18, 18' on two sides facing each other in the same manner as in the embodiment of Example 2. In the embodiment of Example 4, however, current path control portions 19 (or, alternatively, sensor portions 18, 18' as well as current path control portions 19 located on either side of such sensor portions) extend further toward a central portion of semiconductor layer 13 than first current supply portion 16 and second current supply portions 17, 17'. The other structures of the embodiment of Example 4 are the same as in the embodiment of Example 2. Since current path control portions 19 (or, alternatively, sensor portions 18, 18' as well as current path control portions 19) extend further toward to a central portion of semiconductor layer 13, the current path is longer than that in Example 2. Example 5 Fig. 9(a) is a plan view of a Hall element in accordance with yet another embodiment of the present invention. Fig. 9(b) is a sectional view taken along line b-b' of Fig. 9(a). The embodiment of Example 5 provides two structures according to Example 4, i.e., each of the four sides of semiconductor layer 13 provides first and second current supply portions 16, 17, 17', sensor portions 18, 18', and current path control portions 19, respectively. The other structures of the embodiment of Example 5 are the same as in the embodiment of Example 4. The embodiment of Example 5 has a 90° period symmetrical placement of portions 16, 17, 17', 18, 18'. This arrangement is effective to reduce offset voltage due to piezoresistance. In this regard, piezoresistance may change according to crystal direction. For example, piezoresistances may change at a 90° period in the <100> plane of Si. Therefore, in the embodiment of Example 5, when a semiconductor layer having a 90° period change of piezoresistances is used, the offset voltage induced at one side of semiconductor layer 13 is opposite the offset voltage induced at another side facing the one side. As a result, the offset voltages due to the piezo effect act to counterbalance each other. Example 6 Fig. 10(a) is a plan view of a Hall element in accordance with still another embodiment of the present invention. Fig. 10(b) is a sectional view taken along line b-b' of Fig. 10(a). In previous examples, first and second current supply portions 16, 17, 17', sensor portions 18, 18', and current path control portions 19 were arranged on one side of semiconductor layer 13. However, these portions may be separated between one side and a neighboring side of semiconductor layer 13, as illustrated in Figs. 10(a) and 10(b). With reference to Figs. 10(a) and 10(b), in the embodiment of Example 6, first current supply portion 16 1 , second current supply portions 17 1 , 17' 1 sensor portions 18 1 , 18' 1 , and current path control portions 19 1 , compose one set. First current supply portions 16 2 , 16 3 , 16 4 , second current supply portions 17 2 , 17 3 , 17 4 , 17' 2 , 17' 3 , 17 4 , sensor portions 18 2 , 18 3 , 18 4 , 18' 2 , 18' 3 , 18' 4 , and current path control portions 19 2 , 19 3 , 19 4 , also compose one set, respectively. First current supply portions 16 1 , 16 2 , 16 3 , 16 4 and second current supply portions 17' 1 , 17' 2 , 17' 3 , 17' 4 , are positioned along one side of semiconductor layer 13, respectively. Sensor portions 18' 1 , 18' 2 , 18' 3 , 18' 4 are positioned along the one side between first current supply portions 16 1 , 16 2 , 16 3 , 16 4 , and second current supply portions 17' 1 , 17' 2 , 17' 3 , 17' 4 , respectively. Second current supply portions 17 1 , 17 2 , 17 3 , 17 4 are placed along the left side of the one side of semiconductor layer 13. Sensor portions 18 1 , 18 2 , 18 3 , 18 4 are placed along the left side and between first current supply portions 16 1 , 16 2 , 16 3 , 16 4 and second current supply portions 17 1 , 17 2 , 17 3 , 17 4 . As a result of the aforementioned arrangement, second current supply portions 17' 1 , 17' 2 , 17' 3 , 17' 4 fill the role of second current supply portions 17 2 , 17 3 , 17 4 and 17 1 , respectively. These portions are positioned with rotational symmetry with respect to the center of semiconductor layer 13 at a 90° period. This embodiment could also be used to reduce offset voltage due to the piezo effect. Further, a Hall element in accordance with the present invention can be composed of two or more of the above-mentioned embodiments. For example, a Hall element in accordance with the present invention may be composed using a combination of a first structure configured in accordance with Example 1 and a second structure configured in accordance with Example 3 or, alternatively, a combination of a first structure configured in accordance with Example 1 and a second structure configured in accordance with Example 1. It will be apparent to those skilled in the art that various modifications and variations can be made in the Hall element of the present invention without departing from the scope of the claims. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the scope of the invention being indicated by the following claims.

Claims: A Hall element comprising a semi-conductor layer (13) comprising at least one rectangular region of a first conductivity type; a first current supply portion (16) of the first conductivity type disposed in the semi-conductor layer, and a pair of second current supply portions 17, 17' of the first conductivity type disposed in the semi-conductor layer so that the first current supply portion is between them; a pair of sensor portions (18, 18') of the first conductivity type which are also disposed in the semi-conductor layer between the second current supply portions so that the first current supply portion is between the sensor portions; characterised by a peripheral insulator portion (14) extending around the sides of the rectangular region, the current supply portions and the sensor portions all being arranged so as to contact the insulator portion (14); whereby a Hall voltage is induced between the sensor portions in the presence of a magnetic flux perpendicular to the upper surface of the semi-conductor layer during current flow between the first current supply portion (16) and second current supply portions (17, 17') along a current path through the semi-conductor layer (13). A Hall element according to claim 1, further comprising an insulator layer (12) disposed below the semi-conductor layer (13) and in contact with the insulator portion (14). A Hall element according to any preceding claim, further comprising: a gate insulator layer (20) disposed on the upper surface of the semi-conductor layer (13); a gate electrode (21) disposed on the gate insulator layer; at least one of a depletion layer, an accumulation layer, and an inversion layer being formed under the gate insulator layer when a bias voltage is applied to the gate electrode so that current between the first and second current supply portions flows away from the upper surface of the semi-conductor layer. A Hall element according to any preceding claim comprising a rectangular semi-conductor layer (13) having a peripheral insulator portion (14) extending around the sides, at least two opposite sides of the insulator portion each having a first current supply portion (16), a pair of second current supply portions (17, 17') and a pair of sensor portions (18, 18') all being arranged so as to contact the insulator portion (14). A Hall element according to claim 4, wherein each set of facing sides has a respective first current supply portion (16), a pair of second current supply portions (17, 17'), and a pair of sensor portions (18, 18'). A Hall element according to claim 5, wherein, for each set of facing sides, the first current supply portion, the second current supply portions, and the sensor portions are arranged substantially symmetrically with respect to a center of the semi-conductor layer at a 90° period. A Hall element according to claim 1, wherein the insulator also comprises a further portion which extends across the semi-conductor layer so as to divide it into a first region and a second region, and each region has a corresponding set of components including a first current supply portion, a pair of second current supply portions, and a pair of sensor portions. A Hall element according to claim 7, wherein, for each set of components associated with one of the regions of the semi-conductor layer, the first current supply portion, the second current supply portions, and the sensor portions are arranged substantially symmetrically with respect to the insulator portion. A Hall element according to any preceding claim, further comprising current path control means (19) for lengthening the current path between the first and second current supply portions. A Hall element according to claim 9, wherein the current path control means comprises a current path control portion of a second conductivity type disposed between the first and second current supply portions and allowing application of a reverse voltage between the semi-conductor layer and the current path control portion. A Hall element according to claim 10, wherein the current path control portion is positioned further from the insulator portion than the first and second current supply portions. A Hall element according to claim 9, wherein the current path control means comprises a current path control portion of an insulated gate electrode disposed in the semi-conductor layer between the first and second current supply portions and configured so that the current path between the first and second current supply portions is lengthened by forming one of a depletion layer, an accumulation layer and an inversion layer surrounding the insulated gate electrode when a bias voltage is applied to the insulated gate electrode. A Hall element according to any preceding claim wherein the semi-conductor layer is formed on a substrate (11) having an insulator surface (12). A Hall element according to any of claims 1 to 14, wherein the semi-conductor layer is formed on a semi-conductor substrate of a second conductivity type. A Hall element according to any preceding claim, further comprising a second conductivity type semi-conductor layer disposed on the semi-conductor layer of the first conductivity type. A Hall element according to claim 1 in which the said pair of second current supply portions of the first conductivity type are so arranged adjacent the side surface of the insulator portion, that a current between the first and second current supply portions has a current component perpendicular to a plane composed of an interface between the insulator portion (14) and the semi-conductor layer (13). A Hall element according to claim 1, wherein the first and second current supply portions are disposed so that current between first and second current supply portions has a current component perpendicular to a surface including the first and second current supply portions. A current detector including a Hall element according to any preceding claim and further comprising a magnetic yoke having a gap, and a wire carrying an object current and wound around the magnetic yoke; the said Hall element being positioned in the gap.

Inventors: FUJII KANAE, FUNAKI HIDEYUKI, MARUYAMA RYOJI, MOCHIZUKI HIROSHI, FUJII, KANAE, FUNAKI, HIDEYUKI, MARUYAMA, RYOJI, MOCHIZUKI, HIROSHI, FUJII, KANAE, C/O INTELLECTUAL PROPERTY DIV., FUNAKI, HIDEYUKI, C/O INTELLECTUAL PROPERTY DIV., MARUYAMA, RYOJI, C/O INTELLECTUAL PROPERTY DIV., MOCHIZUKI, HIROSHI, C/O INTELLECTUAL PROPERTY DIV.
Applicants: TOSHIBA KK, KABUSHIKI KAISHA TOSHIBA
Application year: 1995
Main classification: H01L43
IPC codes: H01L43