JP2010287755A - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance detection sensitivity of magnetic lines of force in a semiconductor device where a Hall element is formed. <P>SOLUTION: On the surface of a semiconductor layer 11 of a semiconductor substrate 10, the Hall element 20 is formed which includes a pair of contact parts 12A, 12B supplied with a constant current. The Hall element 20 is covered with a thin first insulating film 13, and on the thin first insulating film 13, a first metal layer 15 covering a region 11A between the pair of contact parts 12A, 12B is formed. Further, a second insulating film 16 is formed having an opening part 16A over a part of the first metal layer 15 and covering the first insulating film 13 and first metal layer 15. On the second insulating film 16, a second metal layer 17 is formed which is connected to the first metal layer 15 in the opening part 16A and extends wider than the first metal layer 15. The first metal layer 15 and second metal layer 17 are larger in relative permeability than the second insulating film 16. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a semiconductor device, and more particularly to a semiconductor device in which a Hall element is formed.

  In recent years, semiconductor devices such as ICs having Hall elements as magnetoelectric conversion elements have been developed. An IC provided with a Hall element is mounted on, for example, a small electronic device such as a mobile phone, and the Hall element functions as a magnetic sensor that detects a weak magnetic field in a vibrator of the mobile phone, for example. In an IC for this application, for example, a Hall element is formed on a semiconductor substrate made of silicon, and the Hall element is usually configured to generate a Hall voltage in response to a magnetic field line incident in the vertical direction of the semiconductor substrate. ing.

  A configuration example of such a Hall element will be described below. As shown in FIG. 4, for example, an N− type semiconductor layer 111 is formed on a P type semiconductor substrate 110, and a Hall element 120 is formed on the surface of the semiconductor layer 111. Magnetic field lines are incident on the entire surface of the Hall element 120 with a uniform magnetic flux density in the vertical direction of the semiconductor substrate 110. In addition, since there are no components having a high relative permeability such as metal wiring in the semiconductor layer 111 and the semiconductor substrate 110, the relative permeability of the semiconductor layer 111 and the semiconductor substrate 110 is, for example, about 0.001 to 0. It is substantially uniform with a relative permeability of .004.

On the surface of the semiconductor layer 111 in the Hall element 120, a pair of contact portions 112A and 112B made of, for example, an N + type impurity added layer are formed so as to face each other while being separated from each other. A constant current is supplied from a constant current source (not shown) to the pair of contact portions 112A and 112B, and for example, a hole current I _H flows in the semiconductor layer 111 from the contact portion 112A toward the other contact portion 112B. .

In this configuration, the so-called Hall effect is orthogonal to both the direction of the lines of magnetic force to be detected, that is, the direction perpendicular to the semiconductor substrate 110 and the direction in which the hole current I _H flows between the pair of contact portions 112A and 112B. In the direction, Lorentz force F works to move the charge, and a potential difference is generated. By measuring the potential difference due to the Hall effect as the Hall voltage V _H , it is possible to detect the strength of the magnetic field lines incident on the Hall element 120. The Hall voltage V _H is proportional to the product of the magnitude of the Hall current I _H and the magnetic flux density of the magnetic field lines incident in the vertical direction of the semiconductor substrate 110.

In the Hall element 120, the majority of the hole current _{I H} supplied from the constant current source, a pair of contact portions 112A, flows through the middle semiconductor layer 111 in the region 111A between 112B, in other regions Only a very small current component of the hole current I _H flows through the semiconductor layer 111.

  Further, as described above, the magnetic flux density of the incident magnetic field lines is substantially uniform over the entire surface of the Hall element 120, and the relative magnetic permeability of the semiconductor layer 111 and the semiconductor substrate 110 is substantially uniform.

Accordingly, the pair of contact portions 112A, in the region 111A between 112B, but efficiently Hall effect occurs for the magnetic field lines flows through the majority of the hole current I _H, negligible current component in the other region Since it does not flow, the Hall effect hardly occurs. That is, when the Hall voltage V _H is generated, the region 111A between the pair of contact portions 112A and 112B contributes as the main magnetoelectric conversion region, and the other regions hardly contribute.

JP-A-11-26835 JP 2003-130895 A

Since the above-described semiconductor device such as an IC in which the Hall element 120 is formed is mounted on a small electronic device such as a mobile phone, magnetic field lines having a uniform and small magnetic flux density inside and outside the small electronic device are to be detected. Further, because the small electronic devices are strictly required power saving, current can be supplied to the Hall element 120, i.e. the Hall current I _H is limited to weak. Since the Hall voltage V _H is proportional to the product of the magnitude of the Hall current I _H and the magnetic flux density of the magnetic field lines incident in the vertical direction of the semiconductor substrate 110, the Hall voltage V _H output from the Hall element 120 is It was low and the detection sensitivity of magnetic field lines was low.

In order to increase the Hall voltage V _H , a method of increasing the Hall current I _H or increasing the magnetic flux density of the magnetic lines of force incident on the Hall element 120 can be considered. However, when the Hall current _IH is increased, the power consumption of a semiconductor device such as an IC in which the Hall element 120 is formed increases. Therefore, the semiconductor device is mounted on a small electronic device that is required to save power. Can not be.

  Further, as a method for increasing the magnetic flux density of the magnetic lines of force incident on the Hall element 120, a method of covering the Hall element 120 and forming a ferromagnetic material such as ferrite as a magnetic current collecting plate can be considered. However, since a ferromagnetic material such as a ferrite functioning as a current collecting plate needs to be formed much thicker than a wiring formed in a manufacturing process of a semiconductor device such as a transistor, the Hall element 120 is formed. The size of semiconductor devices such as ICs also increases. Therefore, in this case, it has not been possible to reduce the thickness of the semiconductor device so that it can be mounted on a small electronic device such as a mobile phone.

  The present invention has been made in view of the above problems, and its main features are as follows. That is, a semiconductor device of the present invention includes a semiconductor substrate, a semiconductor layer formed on the surface of the semiconductor substrate, a Hall element including a pair of contact portions formed in the semiconductor layer and supplied with a constant current, and a Hall element And a first insulating film covering the semiconductor layer, a first metal layer formed on the first insulating film and covering a region between the pair of contact portions, and an opening on a part of the first metal layer A second insulating film having an opening to cover the first insulating film and the first metal layer, and connected to the first metal layer in the opening, and on the second insulating film And a second metal layer extending wider than the first metal layer.

  The semiconductor device according to the present invention is characterized in that, in the above structure, each of the first metal layer and the second metal layer has a relative permeability greater than that of the second insulating film. To do.

  In the semiconductor device of the invention having the above structure, the first insulating film is formed thinner than the second insulating film.

  In the semiconductor device of the present invention having the above structure, the second metal layer extends over the second insulating film so as to overlap the entire surface of the semiconductor substrate.

  In the semiconductor device of the present invention having the above structure, the first metal layer and the second metal layer are made of the same metal.

  According to the present invention, the magnetic field lines incident on the second metal layer are focused on a region between the pair of contact layers in which most of the hole current flows and the Hall effect is efficiently generated. Get higher. As a result, a higher Hall voltage can be obtained even with a magnetic field line having a weak magnetic field than in the conventional example, and the detection sensitivity of the magnetic field line can be increased. At that time, it is not necessary to increase the hole current, so that the semiconductor device can save power. In addition, since it is not necessary to form a thick magnetic flux collecting plate such as ferrite, the semiconductor device can be made thin and small.

  Even when the formation area of the Hall element is inevitably reduced due to restrictions on the pattern of the semiconductor device, if the second metal layer is sufficiently wide, the area between the pair of contact layers can be reduced. Since the magnetic field lines are converged and the magnetic flux density is increased, the detection sensitivity of the magnetic field lines can be increased as compared with the conventional example.

It is a top view which shows the semiconductor device by embodiment of this invention. It is sectional drawing along the XX line of FIG. It is sectional drawing along the YY line of FIG. It is a perspective view which shows the semiconductor device by a prior art example.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing the semiconductor device according to the present embodiment. FIG. 1 shows only main components when the Hall element 20 is viewed from above, and the components above the semiconductor layer 11 on which the Hall element 20 is formed. Is not shown. 2 is a cross-sectional view taken along line XX in FIG. 1, and FIG. 3 is a cross-sectional view taken along line YY in FIG.

  As an example, the semiconductor device in which the Hall element 20 is formed according to this embodiment is a device other than the Hall element 20, for example, an IC in which a transistor is also formed on the same semiconductor substrate 10. Description of the configuration of devices other than those will be omitted.

As shown in the plan view of FIG. 1, for example, an N− type semiconductor layer 11 is formed on the surface of, for example, a P type semiconductor substrate 10 constituting an IC, and a Hall element 20 is formed on a part of the surface of the semiconductor layer 11. Is formed. The Hall element 20 functions as a magnetic sensor that generates a Hall voltage V _H according to a magnetic force line that is incident on the surface of the semiconductor substrate 10 in a vertical direction or a substantially vertical direction. The relative magnetic permeability of the semiconductor substrate 10 and the semiconductor layer 11 in the Hall element 20 is substantially uniform over the entire surface, for example, about 0.001 to 0.004. It is assumed that the magnetic flux density of the lines of magnetic force incident on the Hall element 20 is substantially uniform over the entire surface of the semiconductor substrate 10 and the semiconductor layer 11.

  On the surface of the semiconductor layer 11 in the Hall element 20, a pair of contact portions 12A and 12B made of, for example, an N + type impurity addition layer are formed so as to face each other while being separated from each other.

A pair of contact portions 12A, 12B are connected to the constant current source 30, for example, from the contact portion 12A, it is configured toward the other contact portion 12B in the semiconductor layer 11 to flow hole current I _H is ing. Of the hole current I _H, negligible current component, a pair of contact portions 12A, but flows to spread near the outside of the area 11A between 12B, the majority of the hole current I _H is a pair Flows in the region 11A through the shortest path between the contact portions 12A and 12B. Since the Hall current I _H is a constant current used for the magnetoelectric conversion of the Hall element 20, the region 11 A between the pair of contact portions 12 A and 12 B becomes the main magnetoelectric conversion region of the Hall element 20.

In addition, the semiconductor layer 11 in the Hall element 20 has a pair of regions 11A between the pair of contact portions 12A and 12B on a line orthogonal to a line connecting the pair of contact portions 12A and 12B. Output terminals T1 and T2 are connected. Output terminals T1, T2 of the pair, between them, a potential difference caused by the Hall effect by the magnetic force lines and the Hall current I _H that is incident on the region 11A, that is, a terminal for outputting a Hall voltage V _H, for example, It is formed by other contact parts (not shown), metal electrodes, and the like.

The Hall voltage V _H is proportional to the product of the magnitude of the Hall current I _H and the magnetic flux density of the magnetic field lines incident in the vertical direction of the semiconductor substrate 10, and the Hall current I _H flows in the semiconductor layer 11 in the region 11A. Inversely proportional to the depth of the region. Since the depth of the region through which the hole current I _H flows depends on the depth of the pair of contact portions 12A and 12B, the shallower the pair of contact portions 12A and 12B, the higher the hole current I _H is obtained. Can do. Therefore, the depth of the pair of contact portions 12A and 12B is preferably as shallow as possible, but is restricted by the manufacturing process of the semiconductor device, that is, the processing accuracy, the number of steps, and the like. The depth of the pair of contact portions 12A and 12B is, for example, about 0.25 μm as an example of being formed as shallow as possible when formed simultaneously with a drain layer and a source layer of a transistor (not shown).

  Hereinafter, the cross-sectional configuration of the layer above the semiconductor layer 11 will be described with reference to FIGS. 2 and 3. A first insulating film 13 made of, for example, a silicon oxide film or a silicon nitride film is formed on the semiconductor layer 11 including the Hall element 20 so as to cover substantially the entire surface thereof. The first insulating film 13 needs to be formed as thin as several tens of nanometers for the purpose of extremely reducing the magnetic resistance described later. For example, the first insulating film 13 has the same thickness as a gate insulating film of a transistor (not shown). Further, the relative permeability of the first insulating film 13 is, for example, about 0.0002.

An electrode 14A connected to the contact portion 12A and an electrode 14B connected to the contact portion 12B are formed on the first insulating film 13, and the electrodes 14A and 14B are formed on the contact portions 12A and 12B. The Hall current _IH is supplied from the constant current source 30 via the.

Further, in the planar direction of the semiconductor substrate 10, so as to cover the pair of contact portions 12A which flows most of the hole current I _H, the region 11A between 12B, the first metal layer on the first insulating film 13 15 is formed. The first metal layer 15 is a metal, for example, copper or aluminum, used for forming a multilayer wiring or the like in the semiconductor device manufacturing process, and has a thickness of about 0.5 μm to 1 μm, for example. The relative magnetic permeability of the first metal layer 15 is larger than the relative magnetic permeability of the semiconductor substrate 10 and the semiconductor layer 11, and is set with a difference of the order of 3 to 4 digits, for example, about 1.0. is there.

  Further, the second metal layer 15 has an opening 16A that opens on a part of the first metal layer 15 so as to cover the first insulating film 13, the electrodes 14A and 14B, and the first metal layer 15. Insulating film 16 is formed. The second insulating film 16 is made of, for example, a silicon oxide film or a silicon nitride film, and is an interlayer insulating film having a thickness of about 0.5 μm to 1 μm, for example. The first insulating film also includes a region that is not shown. It covers the entire area 13 or substantially the entire area. The relative permeability of the second insulating film 16 is smaller than the relative permeability of the first metal layer 15 and is set with a difference of the order of 4 to 5 digits, for example, about 0.0002. .

  On the second insulating film 16, it is connected to the first metal layer 15 in the opening 16 </ b> A, and overlaps with the first metal layer 15 in the planar direction of the semiconductor substrate 10, and also the first metal layer. A second metal layer 17 extending wider than 15 is formed. The second metal layer 17 is formed so as to cover at least the entire area of the Hall element 20 or substantially the entire area in the planar direction of the semiconductor substrate 10, and preferably extends outside the Hall element 20 and extends to the entire area of the semiconductor substrate 10. It is formed to cover the entire area.

  The second metal layer 17 is a metal used for forming a multilayer wiring or the like in the semiconductor device manufacturing process, such as copper or aluminum, and has a thickness of about 0.5 μm to 1 μm, for example. The relative magnetic permeability of the second metal layer 17 is the same as or substantially the same as the relative magnetic permeability of the first metal layer 15, and is about 1.0, for example. That is, the relative permeability of the first metal layer 15 and the second metal layer 17 are both larger than the relative permeability of the second insulating film 16, for example, with a difference of the order of 4 to 5 digits. Is set.

  As can be seen from the cross-sectional configurations of the first metal layer 15, the second insulating film 16, and the second metal layer 17, the surface of the second metal layer 17 on the side facing the semiconductor substrate 10 is the first metal layer 15. Except for the portion in contact with the metal layer 15, it is in contact with the second insulating film 16 having a relative permeability lower than that of the second metal layer 17. The first metal layer 15 is also surrounded by the second insulating film 16 having a relative permeability lower than that of the first metal layer 15 except for a portion in contact with the second metal layer 17. ing.

  As a result, most of the lines of magnetic force incident on the upper surface of the second metal layer 17 are incident on the second insulating film 16 having a lower relative magnetic permeability than the first metal layer 15 and the second metal layer 17. Instead, the light is guided into the first metal layer 15 through the second metal layer 17. Here, since the second metal layer 17 extends wider than the formation region of the first metal layer 15 in the planar direction of the semiconductor substrate 10 and covers the entire region or substantially the entire region of the Hall element 20, Most of the magnetic field lines incident over a wide range in the planar direction of the semiconductor substrate 10 are focused on the first metal layer 15 with a high magnetic flux density.

Further, the magnetic field lines having a high magnetic flux density focused in the first metal layer 15 do not enter the surrounding second insulating film 16 having a lower relative permeability than the first metal layer 15, so that the hole current I _H is reduced. In the region 11A between the pair of contact portions 12A, 12B through which the majority flows, the semiconductor substrate 10 extends in the vertical direction or substantially vertical direction.

The relative permeability of the first insulating film 13 is the same as that of the second insulating film 16 (for example, about 0.0002), which is higher than that of the first metal layer 15 and the second metal layer 17. The thickness of the first insulating film 13 is only a few tens of nanometers, which is extremely thin compared to the second insulating film 16. Therefore, the magnetic resistance of the first insulating film 13 becomes extremely small in proportion to the thickness of the first insulating film 13. Therefore, the magnetic field lines focused on the first metal layer 15 are not hindered by the slight magnetic resistance of the first insulating film 13, and the first insulating layer is formed along the vertical direction or the substantially vertical direction of the semiconductor substrate 10. passes through the membrane 13, is incident on the semiconductor layer 11 in the region 11A between the pair of contact portions 12A, 12B through which the majority of the hole current _{I H.}

  In particular, when the second metal layer 17 extends to the outside of the Hall element 20 and covers the plane of the semiconductor substrate 10 more widely, more magnetic lines of force are focused on the first metal layer 15. The magnetic flux density of the magnetic lines of force incident on the region 11A between the pair of contact portions 12A and 12B becomes higher.

Thus, a pair of contact portions 12A which flows most of the hole current I _H, the region 11A between 12B, since the magnetic lines of high magnetic flux density incident on the semiconductor layer 11, with high efficiency in the area 11A Hall effect will occur. That is, in the semiconductor layer 11 in the region 11A, in a direction perpendicular to both of the incident magnetic field lines and hole current I _H, worked large Lorentz force F as compared with the conventional example, the terminals T1, T2 of the Hall element 20 The output Hall voltage _VH is increased, and the detection sensitivity of the lines of magnetic force is improved.

As a result, even for the magnetic field lines in a weak magnetic field, it is possible to obtain high Hall voltage V _H as compared with the conventional example, it is possible to increase the detection sensitivity of the magnetic field lines. At that time, there is no need to increase the power consumption of the semiconductor device by increasing the hole current I _H. Further, the semiconductor device is not enlarged by forming a thick ferromagnetic material such as ferrite as the magnetic flux collecting plate. That is, in the present embodiment, the lines of magnetic force are focused using the first metal layer 15 and the second metal layer 17 as described above, but the whole of the first metal layer 15 and the second metal layer 17 combined. Is about 1 μm to 2 μm, for example, which is much thinner than a ferromagnetic material such as ferrite. Therefore, the semiconductor device can be made thin and small.

In addition, the formation area of the Hall element 20 is limited in the planar direction of the semiconductor substrate 10 due to restrictions on the pattern in a semiconductor device such as an IC, for example, restrictions on patterns other than the Hall element 20 such as devices and wirings (not shown). In some cases, the pair of contact layers 12A and 12B must be small. However, in the first place, the Hall voltage V _H is proportional to the product of the magnitude of the Hall current I _H and the magnetic flux density of the magnetic field lines incident in the vertical direction of the semiconductor substrate 10, and the plane of the region 11 A through which most of the Hall current I _H flows. It does not depend on the width of the direction (the width in the direction orthogonal to the direction in which the hole current I _H flows). Therefore, the incident pair of contact layers 12A, and 12B becomes small, even when the majority flows region 11A becomes small hole current I _H, the vertical direction of the semiconductor substrate 10 in the area 11A as described above If the magnetic flux density of the magnetic field lines to be increased is increased, a higher Hall voltage V _H can be obtained as compared with the conventional example, and the detection sensitivity of the magnetic field lines can be increased.

  At this time, the first metal layer 15 is formed small in accordance with the change in the size of the region 11A between the pair of contact layers 12A and 12B, while the width of the second metal layer 17 is not changed. If it is assumed, the magnetic flux density of the magnetic field lines incident in the vertical direction of the semiconductor substrate 10 in the region 11A is higher than that in the above embodiment, and the detection sensitivity of the magnetic field lines can be further increased.

  Needless to say, the present invention is not limited to the above-described embodiment, and modifications can be made without departing from the scope of the invention.

  For example, the second metal layer 17 may be made of the same material as the first metal layer 15 or may be made of a different material as long as it satisfies the above relative permeability relationship. May be.

  When the first metal layer 15 and the second metal layer 17 are made of the same material, they may be simultaneously formed in the same process. In that case, although not shown, after the second insulating film 16 is formed, an opening is formed in the second insulating film 16 on the region 11A between the pair of contact portions 12A and 12B. The first metal layer 15 and the second metal layer 17 may be formed so as to extend on the second insulating film 16.

  Moreover, although not shown in figure, the 1st metal layer 15 and the 2nd metal layer 17 may be connected through the other metal layer which has the same relative magnetic permeability as those. Furthermore, as other metal layers connected between the first metal layer 15 and the second metal layer 17, the same ratio as that of the first metal layer 15 and the second metal layer 17 is used. One or a plurality of metal layers having a magnetic permeability (made of a metal used for multilayer wiring or the like in a semiconductor device manufacturing process, such as copper or aluminum) may be formed. That is, the present invention is also applied to the case where the structure from the first metal layer 15 to the second metal layer 17 has a multilayer wiring structure of three or more layers.

  In the above embodiment, the semiconductor device in which the Hall element 20 is formed has been described by taking as an example an IC other than the Hall element 20, for example, an IC in which a transistor is also formed on the same semiconductor substrate 10. It is not limited to. For example, the present invention is also applied to a semiconductor device in which no device other than the Hall element 20 is formed, and only the Hall element 20 and electrodes connected thereto are formed.

DESCRIPTION OF SYMBOLS 10,100 Semiconductor substrate 11,111 Semiconductor layer 12A, 12B, 112A, 112B Contact part 13 1st insulating film 14A, 14B Electrode 15 1st metal layer 16 2nd insulating film 17 2nd metal layer 20,120 Hall element T1, T2 output terminal

Claims (5)

A semiconductor substrate;
A semiconductor layer formed on the surface of the semiconductor substrate;
A Hall element including a pair of contact portions formed in the semiconductor layer and supplied with a constant current;
A first insulating film covering the Hall element and the semiconductor layer;
A first metal layer formed on the first insulating film and covering a region between the pair of contact portions;
A second insulating film having an opening opening on a part of the first metal layer and covering the first insulating film and the first metal layer;
And a second metal layer that is connected to the first metal layer in the opening and extends wider than the first metal layer on the second insulating film. Semiconductor device.   2. The semiconductor device according to claim 1, wherein each of the relative permeability of the first metal layer and the second metal layer is larger than the relative permeability of the second insulating film.   The semiconductor device according to claim 1, wherein the first insulating film is formed thinner than the second insulating film.   4. The semiconductor device according to claim 1, wherein the second metal layer extends on the second insulating film so as to overlap an entire surface of the surface of the semiconductor substrate. 5. .   5. The semiconductor device according to claim 1, wherein the first metal layer and the second metal layer are made of the same metal.

Images