JP2006147710A - Vertical hall element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vertical Hall element for suppressing variations in element sensitivity caused by variation in ambient temperature, manufacturing conditions, or the like, and for highly maintaining detection precision as a magnetic detecting element. <P>SOLUTION: Impurity concentration at a part adjacent to the pn junction side of diffusion layers (p-type diffusion separation walls) 14, 14a, 14b for electrically dividing the inside of a substrate through a pn junction is enhanced selectively near the substrate surface, where high-concentration regions (n<SP>+</SP>-layer) 15a-15c are formed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a Hall element, and more specifically, when a magnetic field component parallel to the substrate surface (chip surface) is applied to a magnetic detector in the substrate, a Hall voltage signal corresponding to the magnetic field component is generated in the substrate. The present invention relates to a vertical Hall element.

  As is well known, since the Hall element can detect the angle without contact, it is mounted on a so-called Hall IC or the like and used as an angle detection sensor such as a throttle valve opening sensor of an in-vehicle internal combustion engine as a magnetic sensor, for example. It is done. First, the magnetic detection principle of the Hall element will be described with reference to FIG.

  When a magnetic field (magnetism) perpendicular to the current flowing in the material is applied, an electric field (voltage) is generated in a direction perpendicular to both the current and the magnetic field. This phenomenon is called the Hall effect, and the voltage generated here is called the Hall voltage.

For example, when considering a Hall element (conductor) 100 as shown in FIG. 11, the width of the magnetic detection part (Hall plate) of the element is W, the length is L, the thickness is d, and the element and magnetic field If the angle formed is θ, the magnetic flux density is B, and the supply (drive) current (current supplied between the terminals TI and TI ′) is I, the Hall voltage (voltage generated between the terminals TV _{H and} TV _H ′) V _H is ,
V _H = (R _H IB / d) cos θ, R _H = 1 / (qn)
It can be expressed as Here, R _H is the Hall coefficient, q is the charge, and n is the carrier concentration.

As can be seen from the above relational expression, the Hall voltage V _H changes according to the angle θ formed by the Hall element and the magnetic field. Therefore, by using this, the angle can be detected. Thus, the above-described angle detection sensor can be realized by using the Hall element.

  As a general Hall element, for example, a Hall element as described in Non-Patent Document 1, a so-called horizontal Hall element is known. This horizontal Hall element detects a magnetic field component perpendicular to the substrate surface (chip surface).

  Hereinafter, this Hall element (horizontal Hall element) will be further described with reference to FIG. 12A is a plan view of the Hall element, and FIG. 12B is a cross-sectional view taken along line L1-L1 in FIG.

As shown in FIGS. 12A and 12B, this Hall element has a semiconductor layer (P ⁻ sub) 21 made of, for example, P-type silicon, and an N-type conductivity impurity introduced into the surface thereof. The semiconductor region 22 is formed of a diffusion layer (well) formed in a shape. The semiconductor region 22 can also be formed as an N-type semiconductor substrate (N ⁻ sub) or an epitaxial film. In general, a semiconductor material such as silicon has a larger carrier mobility in a semiconductor made of N-type than in a semiconductor made of P-type. Therefore, the semiconductor region 22 is made of an N-type semiconductor material (for example, silicon). Is often used. However, a P-type semiconductor material (P ⁻ layer) may be employed depending on the manufacturing process and structural conditions. Further, as the impurity concentration of the semiconductor region 22 is lower (thinner), the carrier mobility in the same region is increased. Therefore, in order to increase the sensitivity as the Hall element, that is, to obtain a large voltage as the output voltage, the semiconductor region 22 It is more desirable to make the impurity concentration of 22 low (thin). Generally, the semiconductor region 22 (N ⁻ layer) is set to a concentration of “1.0 × 10 ^{14 to} 1.0 × 10 ¹⁷ / cm ³ ”.

  Then, contact regions 23a to 23d are formed on the surface of the semiconductor region 22 in such a manner that the impurity concentration (N-type) on the surface is selectively increased, and the contact regions 23a to 23d and the contact regions 23a to 23d are arranged there. A good ohmic contact is formed between the electrodes (wiring). More specifically, the contact regions 23a and 23b and the contact regions 23c and 23d are arranged at four corners of a region (active region) 22a surrounded by the semiconductor layer 21 in a manner orthogonal to each other. These contact regions 23a to 23d are electrically connected to terminals S and G and terminals V1 and V2, respectively, via respective electrodes (wirings) disposed there.

Here, for example, when a constant drive current is passed from the terminal S to the terminal G, the current flows from the contact region 23a to the contact region 23b. That is, in this case, a current mainly containing a component parallel to the same surface (chip surface) flows near the substrate surface. At this time, when a magnetic field including a component perpendicular to the substrate surface (chip surface) with respect to the current (for example, a magnetic field indicated by an arrow B in FIG. 12) is applied, the terminals V1 and V2 are caused by the Hall effect described above. A Hall voltage corresponding to the magnetic field is generated between Therefore, by detecting the generated Hall voltage signal through the terminals V1 and V2, the magnetic field component to be detected based on the previous relational expression “V _H = (R _H IB / d) cos θ” shown in FIG. That is, a magnetic field component perpendicular to the surface (chip surface) of the substrate used for the Hall element is required. In this Hall element, it is also possible to detect a Hall voltage signal at terminals S and G by passing a drive current through terminals V1 and V2. For this reason, a driving method that offsets an offset voltage (unbalanced voltage) generated in the same element by, for example, periodically replacing the electrodes by using such electrode replacement has been put into practical use.

  As another example of such a horizontal Hall element, there is a horizontal Hall element as shown in FIG. That is, in this horizontal Hall element, a region (active region) 22a surrounded by the semiconductor layer 21 is formed in a cross shape, and the contact regions 23a to 23d are disposed at the respective tip portions. This Hall element also operates in the same manner as the horizontal Hall element shown in FIG.

  In recent years, in addition to the horizontal Hall element, as described in Patent Document 1, for example, a Hall element that detects a magnetic field component parallel to the substrate surface (chip surface), a so-called vertical Hall element has also been proposed. Since this vertical Hall element has a feature that two elements that detect different phases (angles) can be integrated on one chip, the two vertical Hall elements are arranged at an angle of “90 °”. Thus, a rotation sensor or the like that can obtain a linear output (voltage signal) in an angle range of “0 ° to 360 °” can be realized. Hereinafter, an example of the vertical Hall element will be described with reference to FIG. 14A is a plan view of the Hall element, FIG. 14B is a sectional view taken along line L1-L1 in FIG. 14A, and FIG. 14C is FIG. It is sectional drawing along the L2-L2 line of a).

As shown in FIGS. 14A to 14C, the Hall element is roughly composed of a semiconductor layer (P ⁻ sub) 31 made of, for example, P-type silicon, and an N-type conductive impurity on the surface thereof. And a semiconductor region 32 made of, for example, N-type silicon formed by epitaxial growth on the buried layer BL. The buried layer BL functions as a lower electrode, and its impurity concentration is set higher than that of the semiconductor region 32.

In the semiconductor region 32, for example, a P-type diffusion layer (P-type diffusion isolation wall) 34 is formed so as to be connected to the semiconductor layer 31 in order to isolate the Hall element from other elements. . In the region (active region) surrounded by the diffusion layer 34 on the surface of the semiconductor region 32, the contact region (N ⁺ layer) is selectively increased in the impurity concentration (N type) on the surface. 33a to 33e are formed, and a good ohmic contact is formed between the contact regions 33a to 33e and the electrodes (wirings) disposed there. These contact regions 33a to 33e are electrically connected to terminals S, G1, G2, V1, and V2, respectively, through respective electrodes (wirings) disposed therein.

  In addition, as shown in FIG. 14A, the region (active region) surrounded by the diffusion layer 34 extending from the substrate surface to the inside is a P-type diffusion layer through pn junction isolation by each diffusion layer. (P-type diffusion separation walls) 34a and 34b are divided into regions 32a to 32c separating each other. Here, the diffusion layers 34a and 34b are formed so as to be connected to the buried layer BL, and in the regions 32a to 32c, as shown in FIG. A region that is partitioned in a regular manner is formed.

  Regarding these regions, the contact regions 33a, 33d and 33e are formed in the region (element region) 32a, the contact region 33b is formed in the region 32b, and the contact region 33c is formed in the region 32c. More specifically, with respect to these contact regions, the contact region 33a is arranged so as to be sandwiched between both contact regions 33b and 33c and contact regions 33d and 33e orthogonal to these regions. That is, the contact region 33a is arranged to face the contact regions 33b and 33c with the diffusion layers 34a and 34b interposed therebetween. In this Hall element, a region that is electrically partitioned inside the substrate of the region 32a and is sandwiched between the contact regions 33d and 33e is a so-called magnetic detection unit (hole plate) HP. That is, in this Hall element, a Hall voltage signal corresponding to the magnetic field applied here is generated.

Here, for example, when a constant drive current is passed from the terminal S to the terminal G1 and from the terminal S to the terminal G2, the current is buried from the contact region 33a formed on the substrate surface through the magnetic detection unit HP. It flows into the buried layer BL and the contact regions 33b and 33c, respectively. That is, in this case, a current mainly including a component perpendicular to the substrate surface (chip surface) flows through the magnetic detection unit HP. For this reason, in a state where the drive current flows, a magnetic field (for example, a magnetic field indicated by an arrow B in FIG. 14) including a component parallel to the substrate surface (chip surface) is applied to the magnetic detection unit HP of the Hall element. If so, a Hall voltage corresponding to the magnetic field is generated between the terminal V1 and the terminal V2 by the Hall effect described above. Therefore, by detecting the generated Hall voltage signal through the terminals V1 and V2, the magnetic field component to be detected based on the previous relational expression “V _H = (R _H IB / d) cos θ” shown in FIG. That is, a magnetic field component parallel to the surface (chip surface) of the substrate used for the Hall element is required. Incidentally, in this Hall element, the dimension d shown in FIG. 14 corresponds to the thickness of the magnetic detection part (Hall plate) (“d” in the above relational expression). In addition, the direction in which the drive current flows in the Hall element is arbitrary, and the magnetic field (magnetism) can be detected by reversing the direction of the drive current.

As another example of such a vertical Hall element, there is a vertical Hall element described in Non-Patent Document 2, for example.
Japanese Patent Laid-Open No. 1-251763 Ichisuke Maenaka, 3 others, "Integrated 3D magnetic sensor", IEEJ Transactions C, 1989, Vol. 109, No. 7, p483-490 R. S. Popovic, “The Vertical Hall-Effect Device”, IEEE ELECTRON DEVICE LETTER, SEPTEMBER 1984, EDL-5, NO9, P357-358

  By the way, in the horizontal or vertical Hall element as illustrated in FIGS. 12 to 14, movable ions such as sodium (Na) exist in an interlayer insulating film formed on the element surface. For this reason, when the movable ions move with energization or temperature change to the Hall element, the potential in the vicinity of the voltage output terminal (for example, the contact regions 33d and 33e shown in FIG. 14) becomes unstable. May cause a very small Hall voltage signal to be output. This is called time-dependent fluctuation or drift, and causes an error in the detection of a magnetic field based on the same voltage. Especially when the Hall element is used as an angle detection sensor, deterioration of the sensor characteristics is unavoidable and serious. .

  Therefore, conventionally, for example, as shown in FIG. 15, a Hall element or the like in which a conductor plate GP made of aluminum or the like fixed at a predetermined potential (for example, a ground potential) is provided so as to cover the element surface has been proposed. Here, as an example, a case where the conductor plate GP is applied to the horizontal Hall element illustrated in FIG. 12 will be described. FIG. 16 is a graph showing an example of temporal variation (change in output voltage with time).

  Thus, by providing the conductor plate GP so as to cover the element surface, the potential of the element surface is fixed, and the periphery thereof is also placed in a stable potential environment. Therefore, the movement of the movable ions PI in the interlayer insulating film (not shown) is suppressed, the above-described fluctuation of the output voltage caused by the movable ions PI is reduced, and the detection accuracy as the magnetic detection element is kept high. Will be able to. Conventionally, in addition to this, a Hall element in which the element surface is covered with a P-type diffusion layer and the element surface is not in contact with the interlayer insulating film through a pn junction formed between the N-type semiconductor region 22 and the like. Has been proposed.

  However, in the vertical Hall element, for example, as shown in FIG. 17, a depletion layer VR (a region indicated by a two-dot chain line in the drawing) is formed between the semiconductor region 32 and the diffusion layers 34, 34a, and 34b. Is done. Here, a depletion layer is formed when a drive current is supplied from the terminal S to the terminals G1 and G2 in the vertical Hall element illustrated in FIG. That is, in the power supply side region 32a where the terminal S is disposed, the potential is higher than in the ground side region 32b and the region 32c, and the spread of the depletion layer VR is increased accordingly.

  In the vertical Hall element, the inventors have confirmed that the potential of the portion where the depletion layer VR is formed becomes unstable, and the movement of the mobile ions described above becomes active in the vicinity thereof. That is, there is a concern that the above-described variation with time is further increased due to the formation of the depletion layer VR. In addition, as described above, the sensitivity of the Hall element depends on the dimensions of the element, in particular, the dimension of the magnetic detection part (Hall plate). Sensitivity will vary. Specifically, the width (degree of spread) of the depletion layer VR depends on the temperature environment around the element, the process conditions in manufacturing the element, etc., and the element sensitivity becomes unstable according to these conditions.

  As described above, the provision of the conductive plate on the element surface suppresses some variation over time. However, in the case of the vertical Hall element, it cannot be said that a sufficient effect can be obtained. There is still room for improvement in sensitivity variations.

  The present invention has been made in view of such circumstances, and can maintain high detection accuracy as a magnetic detection element while suppressing variations in element sensitivity due to variations in ambient temperature, manufacturing conditions, and the like. An object is to provide a vertical Hall element.

  In order to achieve such an object, according to the first aspect of the present invention, in the state in which a current containing a component perpendicular to the surface of the semiconductor substrate is supplied to a magnetic detection unit provided as a predetermined region in the substrate, When a magnetic field component parallel to the surface of the substrate is applied to the magnetic detection unit, the semiconductor substrate serves as a vertical Hall element that generates a Hall voltage signal corresponding to the magnetic field component in the substrate through a pn junction. Is provided with a structure in which the impurity concentration is selectively increased at least in the vicinity of the substrate surface at a portion adjacent to the pn junction side of the separation wall.

  The inventors pay attention to the fact that the width (degree of spread) of the depletion layer depends on the impurity concentration, and selectively select the impurity concentration of the portion adjacent to the pn junction side of the separation wall at least near the substrate surface. I tried to increase it. Thereby, at least in the vicinity of the substrate surface, the spread of the depletion layer by the separation wall is suppressed, and accordingly, the movement of mobile ions on the substrate surface is also suppressed. For this reason, the above-described variation with time is reduced, and as a result, the detection accuracy as the magnetic detection element can be maintained high. Moreover, in the above structure, since the impurity concentration is selectively increased, the carrier mobility inside the substrate, for example, in the magnetic detection part (hole plate) is maintained high, and as a result, the sensitivity in magnetic detection is high. It will be maintained. In addition, by suppressing the spread of the depletion layer, changes in the element shape accompanying the formation of the depletion layer are naturally suppressed, and this is also suitable for variations in element sensitivity due to fluctuations in ambient temperature, manufacturing conditions, etc. described above. Will be suppressed.

  In addition, this structure is particularly effective when employed in a structure provided with a partition wall for partitioning the magnetic detection portion in the semiconductor substrate, as in the invention described in claim 2. The variation in element sensitivity due to the above-described change in element shape is particularly large when a change occurs in the shape of the magnetic detection unit (Hall plate). For this reason, the structure described in claim 1 is effective when applied to a separation wall that partitions the magnetic detection unit in such a substrate.

In particular, according to the third aspect of the present invention, the effect is great when applied to a separation wall that surrounds the periphery of the magnetic detection unit at least near the surface of the semiconductor substrate.
In the structure according to the second or third aspect, as in the fourth aspect of the invention, the impurity concentration in the portion adjacent to the pn junction side of the separation wall of the semiconductor substrate is selectively increased. It is more effective to have a structure in which the dimension in the depth direction of the high concentration region is set short enough to allow a current including a component perpendicular to the substrate surface to flow through the magnetic detection unit.

  When the structure according to claim 1 is applied to the separation wall that divides the magnetic detection unit (hole plate), the impurity concentration in the portion adjacent to the separation wall increases, so that a large amount of current flows therethrough, and magnetic detection is performed. There is a concern that the amount of current necessary for the current cannot be passed through the magnetic detection unit. In this regard, if the dimension in the depth direction of the high concentration region is defined as in the above-described structure, a sufficient amount of current can be secured in the magnetic detection unit.

  On the other hand, the structure according to claim 1 is also effective when applied to an isolation wall for element isolation that isolates the hall element from other elements as in the invention according to claim 5. . According to such a structure, the above-described effects can be obtained, and the structure has a strong resistance to the influence of disturbance factors (for example, noise caused by circuits around the element).

  Furthermore, at this time, as in the invention according to claim 6, by adopting a structure in which the impurity concentration in the portion adjacent to the outside of the isolation wall for element isolation is selectively increased, resistance to the influence of disturbance factors can be obtained. It can be further increased.

  According to a seventh aspect of the present invention, in the structure according to any one of the first to sixth aspects, a conductor plate is disposed above the surface of the semiconductor substrate so as to cover at least the magnetic detection portion. The structure is as follows.

  By providing such a conductor plate so as to cover the element surface, the electric potential of the element surface is fixed, and the periphery thereof is also placed in a stable electric potential environment. As described above, the movement of the movable ions in the interlayer insulating film is suppressed, and the variation with time due to the movable ions is reduced, so that the detection accuracy as the magnetic detection element can be maintained high. Become. Furthermore, noise from above the substrate can be shielded to protect the Hall element from noise.

  In this case, as the conductor plate, it is effective to employ one made of either polycrystalline silicon or aluminum as in the invention described in claim 8. If any of these is employed as a material, the conductor plate that functions properly as a shield plate against disturbance can be easily formed.

  The vertical Hall element according to claim 1, wherein a current supply pair for supplying a current to the magnetic detection unit and the Hall voltage signal are output to the surface of the semiconductor substrate. When each of the end portions of the voltage output pair is a structure provided as a portion where the impurity concentration is selectively increased on the surface of the semiconductor substrate, the semiconductor substrate according to the invention of claim 9 The depth direction dimension of the high concentration region in which the impurity concentration is selectively increased in the portion adjacent to the pn junction side of the isolation wall is the depth direction of each end of the current supply pair and the voltage output pair. It is effective to have a structure set to the same size as the dimensions.

  According to such a structure, it is possible to easily form a high concentration region in a portion adjacent to the separation wall by using the manufacturing process of each end of the current supply pair and the voltage output pair. It becomes possible to make the process common, and as a result, it becomes easier to realize the above structure.

  In the vertical Hall element according to any one of claims 1 to 9, according to the invention according to claim 10, a current including a component perpendicular to the surface of the semiconductor substrate is at least the magnetic detection. It is effective to have a structure that is guided so as to flow in an oblique direction with respect to the surface of the substrate.

  For example, if a current consisting only of a component perpendicular to the surface of the semiconductor substrate is to flow through the magnetic detection unit, a buried layer (for example, the buried layer BL in FIG. 14) must be provided below the magnetic detection unit. As a result, there is a concern that the potential distribution inside the element may change or the element structure may become complicated. In this regard, according to the above structure, a current including a component perpendicular to the substrate surface can be detected by the magnetic detection unit without causing a change in potential distribution inside the element due to the arrangement of the buried layer or the like, or complicating the element structure. Thus, the original function as a vertical Hall element that generates a Hall voltage corresponding to a magnetic field component parallel to the substrate surface can be maintained.

(First embodiment)
A vertical Hall element according to a first embodiment of the present invention will be described below.
First, the schematic structure of the vertical Hall element according to this embodiment will be described with reference to FIG. In FIG. 1, FIG. 1 (a) is a plan view schematically showing the planar structure of the Hall element, and FIG. 1 (b) is a cross-sectional view taken along line L1-L1 in FIG. 1 (a). 1 (c) is a cross-sectional view taken along line L2-L2 of FIG. 1 (a).

As shown in FIGS. 1A to 1C, the Hall element is roughly composed of a semiconductor layer (P ^- sub) 11 made of, for example, P-type silicon, and an N-type conductivity type on the surface thereof. And an N-type semiconductor region (N well) 12 formed as a diffusion layer (well) by introducing impurities. As described above, a semiconductor material such as silicon has a higher carrier mobility in an N-type semiconductor than in a P-type semiconductor. Therefore, the semiconductor region 12 may be formed of an N-type semiconductor material ( For example, it is desirable to use silicon. However, a P-type semiconductor material (P ⁻ layer) can also be employed depending on the manufacturing process and structural conditions. Further, as the impurity concentration of the semiconductor region 12 is lower (thinner), the carrier mobility in the same region is increased. Therefore, in order to increase the sensitivity as the Hall element, that is, to obtain a large voltage as the output voltage, the same semiconductor region is used. It is more desirable to make the impurity concentration of 12 low (thin).

Also in this Hall element, for example, a P-type diffusion layer (P-type diffusion separation wall) 14 is formed in the semiconductor layer 11 in order to isolate the Hall element from other elements. A region (active region) on the surface of the semiconductor region 12 and surrounded by the diffusion layer 14 is contact region (N ⁺ layer) in such a manner that the impurity concentration (N type) on the surface is selectively increased. ) 13a to 13e are formed. As a result, a good ohmic contact is formed between each of these contact regions and the electrode (wiring) disposed there. These contact regions 13a to 13e are electrically connected to terminals S, G1, G2, V1, and V2, respectively, through respective electrodes (wirings) disposed therein. Of these, the contact regions 13b and 13c are paired with the contact region 13a to form a current supply pair, and the contact regions 13d and 13e correspond to the end portions of the voltage output pair. It is.

Further, as shown in FIG. 1A, the region (active region) surrounded by the diffusion layer 14 extending from the substrate surface to the inside is formed into a P-type diffusion layer through pn junction isolation by each diffusion layer. (P-type diffusion separation walls) 14a and 14b are divided into regions 12a to 12c that separate each other. And as FIG.1 (c) shows, in these area | regions 12a-12c, the area | region divided electrically also in the inside of a board | substrate is formed. Further, the impurity concentration is selectively increased in the vicinity of the substrate surface in the portions adjacent to the inner peripheral side (pn junction side) of the diffusion layers 14 and 14a and 14b that electrically partition these regions 12a to 12c. High-concentration regions (N ⁺ layers) 15a to 15c are formed there. The dimension in the depth direction of the high concentration region 15a is short enough to allow a current including a component perpendicular to the substrate surface to flow through the magnetic detection unit HP. For example, the diffusion layers 14a and 14b partitioning the magnetic detection unit HP It is set to “½” or less of the depth dimension. Further, here, the dimension in the depth direction of the high concentration regions 15a to 15c is set to about the same as the dimension in the depth direction of the contact regions 13a to 13e, for example, about "1 μm".

  In these regions, the contact regions 13a, 13d and 13e are formed in the region (element region) 12a, the contact region 13b is formed in the region 12b, and the contact region 13c is formed in the region 12c. More specifically, with respect to these contact regions, the contact region 13a is arranged so as to be sandwiched between both contact regions 13b and 13c and contact regions 13d and 13e orthogonal to these regions. That is, the contact region 13a is arranged to face the contact regions 13b and 13c with the diffusion layers 14a and 14b interposed therebetween. In this Hall element, a region that is electrically partitioned inside the substrate of the region 12a and is sandwiched between the contact regions 13d and 13e is a so-called magnetic detection unit (hole plate) HP. That is, in this Hall element, a Hall voltage signal corresponding to the magnetic field applied here is generated.

  Here, for example, when a constant driving current is passed from the terminal S to the terminal G1 and from the terminal S to the terminal G2, the current flows from the contact region 13a formed on the substrate surface to the magnetic detection unit HP and the diffusion layer. It flows to the contact regions 13b and 13c through the lower part of 14a and 14b, respectively. That is, in this case, a current including a component perpendicular to the substrate surface (chip surface) flows through the magnetic detection unit HP. However, this vertical Hall element has a structure in which the buried layer (see the buried layer BL in FIG. 14) is omitted, so that the drive current is at least oblique to the substrate surface in the magnetic detection unit HP. It will be guided to flow. Therefore, unlike the conventional vertical Hall element shown in FIG. 14, in this vertical Hall element, the drive current in the magnetic detection unit HP is not substantially perpendicular to the substrate surface, but is oblique to the substrate surface. Will flow.

  Further, the dimension in the depth direction of the high concentration region 15a is set to be short enough to allow a current including a component perpendicular to the substrate surface to flow through the magnetic detection unit HP, thereby increasing the height close to the magnetic detection unit HP. A situation in which a large amount of current flows through the concentration region 15a and a current amount necessary for magnetic detection cannot be supplied to the magnetic detection unit HP is avoided. That is, a sufficient amount of current is secured in the magnetic detection unit HP.

If a magnetic field including a component parallel to the substrate surface (chip surface) (for example, a magnetic field indicated by an arrow B in FIG. 1) is applied to the magnetic detection unit HP of the Hall element in a state where this driving current is applied. Due to the Hall effect described above, a Hall voltage corresponding to the magnetic field is generated between the terminal V1 and the terminal V2. Therefore, by detecting the generated Hall voltage signal through the terminals V1 and V2, the magnetic field component to be detected based on the previous relational expression “V _H = (R _H IB / d) cos θ” shown in FIG. That is, a magnetic field component parallel to the surface (chip surface) of the substrate used for the Hall element is required. Incidentally, in this Hall element, the dimension d shown in FIG. 1 corresponds to the thickness (“d” in the above relational expression) of the magnetic detection part (Hall plate). In addition, the direction in which the drive current flows in the Hall element is arbitrary, and the magnetic field (magnetism) can be detected with the direction of the drive current being reversed.

  In the vertical Hall element according to this embodiment, the impurity concentration in the portion adjacent to the pn junction side of diffusion layers (P-type diffusion separation walls) 14 and 14a and 14b that electrically partitions the inside of the substrate through the pn junction is set. The height was selectively increased in the vicinity of the substrate surface. Thereby, in the vicinity of the substrate surface, the spread of the depletion layer due to the diffusion layers 14 and 14a and 14b is suppressed, and accordingly, the movement of mobile ions on the substrate surface is also suppressed. For this reason, the above-described variation with time is reduced, and as a result, the detection accuracy as the magnetic detection element can be maintained high. Moreover, since the impurity concentration is kept low (thin) in the semiconductor region 12, a large mobility can be obtained as the carrier mobility in the magnetic detection unit HP and the like, so that the sensitivity at the time of magnetic detection is maintained high. Become. In addition, by suppressing the spread of the depletion layer, changes in the element shape accompanying the formation of the depletion layer are naturally suppressed, and this is also suitable for variations in element sensitivity due to fluctuations in ambient temperature, manufacturing conditions, etc. described above. Will be suppressed.

As described above, according to the vertical Hall element according to this embodiment, many excellent effects as described below can be obtained.
(1) The impurity concentration in the portion adjacent to the pn junction side of the diffusion layers (P-type diffusion separation walls) 14 and 14a and 14b that electrically partitions the inside of the substrate through the pn junction is selectively increased near the substrate surface. Then, high concentration regions (N ⁺ layers) 15a to 15c were formed there. As a result, the above-described variation with time is reduced, and as a result, the detection accuracy as the magnetic detection element can be maintained high. In addition, the carrier mobility in the magnetic detection unit HP or the like is maintained high, and as a result, the sensitivity in magnetic detection is also maintained high. Furthermore, the above-described variations in device sensitivity due to fluctuations in ambient temperature, manufacturing conditions, and the like are preferably suppressed.

  (2) Further, by maintaining high detection accuracy as a magnetic detection element, it becomes possible to detect minute magnetic fluctuations that have been difficult in the past, and can be applied to new fields. It becomes like this. In addition, when applied to the conventional field, it is possible to improve the yield, reduce the cost, and consequently save energy.

(3) The high concentration regions (N ⁺ layers) 15a to 15c are provided on the pn junction side with respect to the diffusion layers (separation walls) 14 and 14a and 14b surrounding the magnetic detection unit HP. The variation in element sensitivity due to the above-described change in element shape is particularly large when a change occurs in the shape of the magnetic detection unit (Hall plate). In this regard, in the above structure, since the high concentration regions 15a to 15c are provided in the diffusion layer (separation wall) surrounding the magnetic detection unit HP, the shape change of the magnetic detection unit HP is suitably suppressed, and consequently The above-described variation in element sensitivity is more preferably suppressed.

  (4) The dimension in the depth direction of the high concentration region 15a is set to be short enough to allow a current including a component perpendicular to the substrate surface to flow through the magnetic detection unit HP. This prevents a large amount of current from flowing in the high-concentration region 15a adjacent to the magnetic detection unit HP and prevents the amount of current necessary for magnetic detection from flowing to the magnetic detection unit HP, and a sufficient amount of current for the magnetic detection unit HP Can be secured.

(5) High-concentration regions (N ⁺ layers) 15a to 15c are provided on the pn junction side with respect to the element isolation diffusion layer (separation wall) 14 that isolates the Hall element from other elements. As a result, the structure has a strong resistance against the influence of disturbance factors (for example, noise caused by circuits around the element).

  (6) The dimension in the depth direction of the high concentration regions 15a to 15c is set to be approximately the same as the dimension in the depth direction of the contact regions 13a to 13e. According to such a structure, it is possible to easily form the high-concentration regions 15a to 15c using the manufacturing process of the contact regions 13a to 13e, that is, it is possible to share both manufacturing processes. As a result, the above structure can be realized more easily.

  (7) The structure is such that a current including a component perpendicular to the substrate surface (chip surface) is guided to flow in an oblique direction with respect to the substrate surface at least in the magnetic detection unit HP. As a result, a current containing a component perpendicular to the substrate surface flows to the magnetic detection unit HP without causing a change in potential distribution inside the element due to the arrangement of the buried layer or the like, or complicating the element structure. Thus, the original function as a vertical Hall element that generates a Hall voltage corresponding to a magnetic field component parallel to the substrate surface can be maintained.

(Second Embodiment)
FIG. 2 shows a second embodiment of the vertical Hall element according to the present invention.
Hereinafter, with reference to FIGS. 2A to 2C, the structure of the vertical Hall element according to this embodiment will be described focusing on the differences from the first embodiment. 2A corresponds to the plan view of FIG. 1A, and FIG. 2B is a cross-sectional view taken along line L1-L1 in FIG. FIG. 2C is a cross-sectional view taken along line L2-L2 of FIG. In each of these drawings, the same elements as those shown in FIG. 1 are denoted by the same reference numerals, and redundant description of these elements is omitted.

  As shown in FIG. 2, this vertical Hall element also basically has the same structure as the vertical Hall element of the first embodiment illustrated in FIG. The operation mode is also as described above. However, in this embodiment, a structure in which a conductor plate GP made of, for example, aluminum or polycrystalline silicon fixed at a predetermined potential (for example, ground potential) is provided so as to cover the element surface. The diffusion layers 14 and 14a and 14b are also fixed to a predetermined potential (for example, ground potential) through appropriate wiring. In addition, as a material of the conductor plate GP, any conductor material can be adopted, and for example, a metal other than aluminum can also be adopted.

  By providing such a conductor plate GP so as to cover the element surface, the electric potential of the element surface is fixed, and the periphery thereof is also placed in a stable electric potential environment. For this reason, the movement of movable ions in an interlayer insulating film (not shown) formed on the substrate surface is suppressed, and the variation with time due to the movable ions is reduced, and as a result, the detection accuracy as a magnetic detection element is maintained high. Will be able to. Furthermore, noise from above the substrate can be shielded to protect the Hall element from noise.

  As described above, according to the vertical Hall element according to this embodiment, in addition to the same effects as the effects (1) to (7) of the previous first embodiment or the effects equivalent thereto. Further, the following effects can be obtained.

  (8) The conductor plate GP is arranged above the substrate surface side so as to cover the element surface including the magnetic detection part HP. This makes it possible to maintain high detection accuracy as a magnetic detection element. Furthermore, noise from above the substrate can be shielded to protect the Hall element from noise.

  (9) Aluminum or polycrystalline silicon is adopted as the material of the conductor plate GP. This makes it possible to easily form a conductor plate GP that functions properly as a shield plate against disturbance.

(Other embodiments)
In addition, each said embodiment can also be implemented with the following aspects.
In the above embodiments, the depth direction dimensions of the high concentration regions 15a to 15c are set to be approximately the same as the depth direction dimensions of the contact regions 13a to 13e. However, this is not an essential configuration, and the depth direction dimensions of the high concentration regions 15a to 15c are arbitrary. Further, the first embodiment will be described as long as the dimension of the high-concentration region 15a adjacent to the magnetic detection unit HP is set short enough to allow a current including a component perpendicular to the substrate surface to flow through the magnetic detection unit HP. The effect similar to or equivalent to the effect of (4) above can be obtained.

For example, as shown in FIG. 3, in the vertical Hall element according to the first embodiment, a high-concentration region (N ⁺ layer) 16 is provided in a portion close to the outside of the diffusion layer (separation wall) 14 for element isolation. It can also be set as the structure which provided. According to such a structure, it becomes possible to further enhance the tolerance against the influence of disturbance factors (for example, noise caused by circuits around the element).

In each of the above embodiments, a vertical Hall element composed of a pair of voltage output is assumed. However, the present invention is not limited to this, and the vertical Hall element including two or more voltage output pairs is also applicable. The present invention can be similarly applied. For example, as shown in FIG. 4, in the vertical Hall element according to the first embodiment, the contact regions 17b and 18b corresponding to the voltage output terminal and the contact regions 13b and 13c corresponding to the current supply terminal, and the contact It is good also as a structure which each provided the area | regions 17c and 18c. In such a structure, the characteristics of the terminals V3b and V4b provided in each of the contact regions, and the output voltage ( _Vout ) of the terminals V3c and V4c are the same as the terminal V1 of the vertical Hall element shown in FIG. The characteristics are opposite to the output characteristics of V2 (polarity is reversed).

  Further, the number of current supply pairs is not limited to two and is arbitrary. For example, the present invention can be similarly applied to a vertical Hall element including a pair of current supply pairs. For example, as shown in FIG. 5, the present invention can be applied to the vertical Hall element according to the first embodiment even when the region 12c, that is, the contact region 13c on the terminal G2 side is omitted. it can. In addition, with such a structure, the area of about “1/3” is reduced as compared with the vertical Hall element shown in FIG. 1, and the size can be greatly reduced. The operation mode of such a Hall element is also basically the same as that of the previous vertical Hall element exemplified in FIG.

In the above embodiments, the high concentration regions (N ⁺ layers) 15a to 15c are provided on the pn junction side with respect to the diffusion layers (separation walls) 14 and 14a and 14b surrounding the magnetic detection unit HP. did. However, with respect to the diffusion layers (separation walls) 14a and 14b and the element isolation diffusion layer (separation wall) 14 that partition the magnetic detection unit HP in the substrate, a high concentration region (N ⁺ layer) 15a is formed on the pn junction side. If the structure is provided with ˜15c, that is, for example, the structure shown in FIG. 6, the effects according to the effects (3) and (5) according to the first embodiment can be obtained. it can. Further, for example, as shown in FIG. 7, even if the high concentration regions (N ⁺ layers) 15 a to 15 c are provided only in the diffusion layers (separation walls) 14 a and 14 b that partition the magnetic detection unit HP in the substrate, The effect according to the effect (3) of the first embodiment can be obtained. If such a structure is adopted and the high concentration region (N ⁺ layer) is provided only where the potential gradient is steep in the path of the drive current, that is, where the depletion layer has a large spread, the structure is simple. While maintaining the above, the above-mentioned effects can be obtained efficiently.

In each of the above embodiments, the high concentration regions (N ⁺ layers) 15a to 15c are provided for all the regions 12a to 12c. However, the present invention is not limited to this, for example, as shown in FIG. A structure in which the high concentration region (N ⁺ layer) 15a is provided only in the region 12a may be employed. Also in this case, for example, as shown in FIG. 9, by providing a high concentration region (N ⁺ layer) 16 in a portion close to the outside of the diffusion layer (separation wall) 14 for element isolation, the influence of disturbance factors can be prevented. Resistance can be increased.

Furthermore, the separation wall that divides the magnetic detection unit HP in the substrate and the separation wall for element separation need not be a diffusion layer (diffusion separation wall). For example, in the case of a vertical Hall element as shown in FIG. No separation wall is required. As shown in FIG. 10, in this vertical Hall element, contact regions 13a to 13c corresponding to current supply terminals and contact regions 13d and 13e corresponding to voltage output terminals are arranged in a line. In such a vertical Hall element as well, a high concentration region (N ⁺ layer) 19 is provided in a portion close to the pn junction side of the semiconductor layer 11 (separation wall) that electrically partitions the inside of the substrate through the pn junction. An effect can be obtained. The operating principle of this vertical Hall element is the same as that of the vertical Hall element described in Non-Patent Document 2.

In each of the above embodiments, the voltage output terminal and the current supply terminal are both provided as contact regions (N ⁺ layers) in which the concentration of the conductive impurities on the substrate surface is selectively increased. However, this is not an essential configuration. For example, a wiring (electrode) may be provided directly on the semiconductor region 12 without providing such a contact region.

  In the above embodiment, constant current driving has been described as an example of a vertical Hall element driving method. However, the vertical Hall element driving method is arbitrary, and may be driven by constant voltage driving, for example. it can.

In each of the above embodiments, the present invention can be similarly applied to a structure in which the conductivity type of each element constituting the semiconductor substrate is switched, that is, a structure in which the P type and the N type are switched. That is, the same effect can be obtained when the high concentration region is provided as the P ⁺ layer.

  In each of the above embodiments, silicon is used as the material for the substrate, but other materials may be appropriately employed depending on the manufacturing process, structural conditions, and the like. For example, compound semiconductor materials such as GaAs, InSb, InAs, and SiC, and other semiconductor materials such as Ge (germanium) can also be used. In particular, GaAs and InAs are materials having excellent temperature characteristics, and are effective in increasing the sensitivity of the Hall element.

  In each of the above embodiments, the semiconductor region 12 is formed as a diffusion layer. However, the present invention is not limited to this. For example, as in the conventional vertical Hall element illustrated in FIG. The present invention can be similarly applied to a structure in which is formed as an epitaxial film. In general, when such an epitaxial substrate is employed, the buried layer BL (FIG. 14) is often used. In addition, an SOI (Silicon On Insulator) substrate or the like can be employed as appropriate.

  After all, if the structure is such that the impurity concentration in the portion adjacent to the pn junction side of the separation wall that electrically partitions the inside of the substrate through the pn junction is selectively increased at least near the substrate surface, the first The effect similar to the effect of said (1) and (2) by embodiment of this, or the effect according to it can be acquired.

In the first embodiment of the vertical Hall element according to the present invention, (a) is a plan view schematically showing the schematic structure of the Hall element, and (b) is taken along line L1-L1 in (a). Sectional drawing, (c) is a sectional view along line L2-L2 in (a). Regarding the second embodiment of the vertical Hall element according to the present invention, (a) is a plan view schematically showing the schematic structure of the Hall element, and (b) is taken along line L1-L1 in (a). Sectional drawing, (c) is a sectional view along line L2-L2 in (a). The top view which shows the modification of the vertical Hall element based on this invention. The top view which shows another modification of the vertical Hall element based on this invention. The top view which shows another modification of the vertical Hall element based on this invention. The top view which shows another modification of the vertical Hall element based on this invention. The top view which shows another modification of the vertical Hall element based on this invention. The top view which shows another modification of the vertical Hall element based on this invention. The top view which shows another modification of the vertical Hall element based on this invention. Regarding another modification of the vertical Hall element according to the present invention, (a) is a plan view schematically showing a schematic structure of the Hall element, and (b) is a cross-sectional view taken along line L1-L1 of (a). . The perspective view which shows the magnetic detection principle of a Hall element. (A) is a top view which shows typically the planar structure of the Hall element about an example of the conventional Hall element (horizontal type Hall element), (b) is sectional drawing along the L1-L1 line of (a). The top view which shows typically the schematic structure of the Hall element about another example of the conventional Hall element (horizontal Hall element). As for an example of a conventional Hall element (vertical Hall element), (a) is a plan view schematically showing a planar structure of the Hall element, (b) is a sectional view taken along line L1-L1 in (a), (C) is sectional drawing along the L2-L2 line of (a). The perspective view which shows an example which applied the conductor plate to the conventional Hall element (horizontal Hall element). The graph which shows an example of a time-dependent fluctuation | variation (aging voltage change). The top view which shows the formation aspect of the depletion layer in the conventional Hall element (vertical Hall element).

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Semiconductor layer, 12 ... Semiconductor region, 12a-12c ... area | region, 13a-13e, 17b, 17c, 18b, 18c ... Contact region (N ⁺ layer), 14, 14a, 14b ... Diffusion layer, 15a-15c, 16 , 19 ... high concentration region (N ⁺ layer), BL ... buried layer, GP ... conductor plate, HP ... magnetic detection part.

Claims (10)

In a state where a current including a component perpendicular to the surface of the semiconductor substrate is supplied to a magnetic detection unit provided as a predetermined region in the substrate, a magnetic field component parallel to the surface of the substrate is applied to the magnetic detection unit. A vertical Hall element that generates a Hall voltage signal corresponding to the magnetic field component in the substrate,
The semiconductor substrate includes a separation wall that electrically partitions the inside of the substrate through a pn junction, and a portion of the separation wall adjacent to the pn junction side has an impurity concentration selectively increased at least in the vicinity of the substrate surface. A vertical Hall element characterized by The vertical Hall element according to claim 1, wherein the separation wall partitions the magnetic detection unit in the semiconductor substrate. The vertical Hall element according to claim 1, wherein the separation wall surrounds the periphery of the magnetic detection unit at least near the surface of the semiconductor substrate. The magnetic detection unit generates a current in which a dimension in a depth direction of a high concentration region in which a concentration of impurities is selectively increased in a portion adjacent to the pn junction side of the separation wall of the semiconductor substrate includes a component perpendicular to the substrate surface. The vertical Hall element according to claim 2, wherein the vertical Hall element is set to be short enough to circulate in a vertical direction. The vertical Hall element according to claim 1, wherein the isolation wall is an isolation wall for element isolation that isolates the Hall element from other elements. The vertical Hall element according to claim 5, wherein the impurity concentration in a portion adjacent to the outside of the isolation wall for element isolation is selectively increased. The vertical Hall element according to any one of claims 1 to 6, wherein a conductor plate is disposed above the surface of the semiconductor substrate so as to cover at least the magnetic detection unit. The vertical Hall element according to claim 7, wherein the conductor plate is made of either polycrystalline silicon or aluminum. On the surface of the semiconductor substrate, each end of a current supply pair for supplying current to the magnetic detection unit and a voltage output pair for outputting the Hall voltage signal is used to select an impurity concentration on the surface of the semiconductor substrate. The dimension in the depth direction of the high concentration region in which the impurity concentration is selectively increased in the portion adjacent to the pn junction side of the separation wall of the semiconductor substrate is provided as the height of the current supply pair. The vertical Hall element according to any one of claims 1 to 8, wherein the vertical Hall element is set to be approximately the same as a dimension in a depth direction of each end portion of the voltage output pair. The vertical Hall element according to any one of claims 1 to 9, wherein a current including a component perpendicular to the surface of the semiconductor substrate is guided so as to flow in an oblique direction with respect to the surface of the substrate at least in the magnetic detection unit.

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