JP2010093213A - Semiconductor element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a less deteriorated characteristics semiconductor element by reducing an influence on element characteristics by diffusion of metal to a compound semiconductor film. <P>SOLUTION: A semiconductor element includes: a compound semiconductor film 1 having a mesa structure formed on a substrate; a short-circuitted electrode 2 formed on a compound semiconductor film 1; and a takeout electrode 3 for electrical connection with the outside. The short-circuitted electrode 2 and the takeout electrode 3 joins with a mesa part of the compound semiconductor film 1. A junction plane of the takeout electrode 3 and the compound semiconductor film 1 with a long side end part of the mesa structure ranges between -15 to +15° with respect to at least one plane among parallel plane to (111) plane, (1-1-1) plane, (-11-1) plane, and (-1-11) plane in a range of -15 to +15° with respect to a plane parallel to (11-1) plane, (1-11) plane, (-111) plane, and (-1-1-1) plane no junction part is formed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor element.

Hereinafter, a magnetoelectric conversion element will be described as an example of the semiconductor element.
In general, a magnetoelectric conversion element applies a bias between the input terminals of the element, and the path of carriers flowing in the element changes according to the change of the surrounding magnetic field, thereby generating an electromotive force at the output terminal or the resistance of the element. It is an element that measures the magnetic field strength by changing the value. Such a magnetoelectric conversion element is used as a detection element for detecting the rotation of a gear made of a ferromagnetic material.

The magnetoresistive effect of the magnetoelectric conversion element can be described by the following equation.
_{ΔR / R 0 α (μB)} 2: low applied magnetic field when _{ΔR / R 0 α (μB)} : where at high applied magnetic field, is _{ΔR = R B -R 0, R} B is the resistance in the magnetic field, R ₀ is a resistance value without a magnetic field, μ is an electron mobility, and B is an applied magnetic field. ΔR / R ₀ corresponds to the sensitivity of the magnetoelectric conversion element, and is proportional to the square of the electron mobility μ in a low magnetic field and proportional to the electron mobility μ in a high magnetic field. Therefore, in order to obtain higher sensitivity (ΔR / R ₀ ), the magnetoelectric conversion element uses a bulk of InSb having a high electron mobility μ, a thin film formed by a vacuum deposition method, or the like.

  In a magnetoelectric conversion element, a compound semiconductor thin film is generally formed on a substrate in a meander shape, and a plurality of short-circuit electrodes are formed thereon. In addition, an extraction electrode for electrical connection with the outside is provided, and an external terminal is connected to the extraction electrode, whereby electrical connection with the outside is performed.

  The structures of the short-circuit electrode and the extraction electrode are determined in consideration of the electrical resistivity and the bonding property of the extraction electrode. In general, Au, Al, Cu, or the like is used for the uppermost electrode layer of the electrode formed in a multilayer structure. In addition, the lowermost electrode layer is often made of Cr, Ni, Ti, or Pd alone or an alloy made of a combination thereof in order to improve adhesion to the compound semiconductor thin film. From the viewpoint of preventing the metal constituting the electrode from diffusing into the semiconductor thin film, the lowermost electrode layer is preferably thicker. However, when the lowermost electrode layer is thick, the resistance of the electrode increases. Therefore, the sensitivity as a magnetoelectric conversion element is reduced.

  As a solution to the problem that the metal constituting the electrode diffuses into the semiconductor thin film and the characteristics of the magnetoelectric conversion element change, the curing temperature of the heat-resistant resin that forms a protective film that protects the semiconductor thin film and the short-circuit electrode Is known to be 280 ° C. or lower (see, for example, Patent Document 1).

JP 2003-304209 A

  In recent years, miniaturization of magnetoelectric transducers has been demanded due to high-resolution detection and miniaturization of rotating media. However, with the miniaturization of magnetoelectric conversion elements, small characteristic changes such as changes in the characteristics of compound semiconductors and changes in contact resistance with electrodes have come to have a great influence on the characteristics of magnetoelectric conversion elements. In a fine magnetoelectric conversion element, even if the method described in Patent Document 1 described above is used, the characteristics are deteriorated, which is insufficient to obtain a highly reliable magnetoelectric conversion element.

  The present invention has been made in view of such problems, and the object of the present invention is to reduce the influence of metal diffusion into the compound semiconductor film on the characteristics of the device, and as a result, to reduce the characteristic fluctuation. An object of the present invention is to provide a semiconductor device.

  In order to achieve such an object, the invention described in claim 1 includes a compound semiconductor film having a mesa structure formed on a substrate, a short-circuit electrode formed on the compound semiconductor film, and an outside. A semiconductor element comprising an extraction electrode for electrical connection, wherein the short-circuit electrode and the extraction electrode are joined to a mesa portion of the compound semiconductor film, and the extraction electrode and the mesa of the compound semiconductor film The joint surface with the long side end of the structure is at least one of a (111) plane, a (1-1-1) plane, a (-11-1) plane, and a plane parallel to the (-1-11) plane. It is in the range of −15 ° to + 15 ° with respect to one plane, and is parallel to the (11-1) plane, the (1-11) plane, the (−111) plane, and the (−1-1-1) plane. In the range of -15 ° to + 15 ° with respect to the surface, it is formed so that there is no joint. It is characterized in.

  A second aspect of the present invention is the semiconductor element according to the first aspect, wherein an upper surface of the mesa structure of the compound semiconductor film is a plane parallel to a (100) plane, and the extraction electrode and the compound semiconductor The joint surface of the mesa structure with the long side end of the film is in a range of −15 ° to + 15 ° with respect to the (111) plane or the plane parallel to the (1-1-1) plane. Features.

The invention according to claim 3 is the semiconductor element according to claim 1 or 2, wherein the compound semiconductor film is In _a Al _b Ga _(1-ab) As _x Sb _(1-x) (0 ≦ a ≦ 1, 0 ≦ b <1, 0 ≦ a + b ≦ 1, 0 ≦ x ≦ 1).

  Invention of Claim 4 is a semiconductor element in any one of Claim 1 thru | or 3, Comprising: The said short circuit electrode and the said extraction electrode are comprised by the single layer or the multilayer which consists of the single-piece | unit of Au, or the alloy of Au It is characterized by being.

  Invention of Claim 5 is a semiconductor element in any one of Claim 1 thru | or 4, Comprising: The lowermost layer of the said short circuit electrode and the said extraction electrode is Ti, and the thickness of the said Ti is 10-200 nm It is characterized by being.

  A sixth aspect of the present invention is the semiconductor element according to any one of the first to fifth aspects, wherein the semiconductor element is a Hall element or a magnetoresistive element.

  A seventh aspect of the present invention is the semiconductor element according to any one of the first to sixth aspects, wherein a short side of the compound semiconductor film is 5 μm to 150 μm in the same compound semiconductor film. The distance between the short-circuit electrodes is 0.5 μm to 30 μm.

  According to the present invention, it is possible to provide a semiconductor element having a small characteristic fluctuation even in a fine magnetoelectric conversion element.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol represents the same thing in several drawing, and the repeated description is abbreviate | omitted.

  FIG. 1 shows a magnetoelectric transducer according to an embodiment of the present invention. More specifically, FIG. 1A shows the structure of the magnetoelectric conversion element, and FIG. 1B shows the plane orientation of the magnetoelectric conversion element.

  This magnetoelectric conversion element includes a magnetosensitive part formed of a compound semiconductor film 1 having a resistance value changed by a magnetic field, formed in a meander shape on an insulating substrate, and a plurality of short-circuit electrodes 2 formed on the compound semiconductor film. Prepare. In addition, an extraction electrode 3 for electrical connection to the outside is provided, and an external terminal is connected to the extraction electrode 3, whereby electrical connection to the outside is performed.

The compound semiconductor constituting the magnetosensitive part of the magnetoelectric conversion element is a bulk of InSb or InAs, or InSb, InAs, or In _a Al _b Ga _(1-ab) As _x Sb _(1-x) (0 ≦ a + b ≦ 1, 0 ≦ x ≦ 1) is preferable. However, in the present invention, any compound semiconductor may be used, and the constituent elements thereof are not limited. The thickness of the compound semiconductor film is usually 0.1 to 4 μm, preferably 0.2 to 2 μm, and more preferably 0.3 to 1.5 μm. Further, it may be doped with impurities such as Si, Sn, S, Se, Te, Ge, or C.

  When the compound semiconductor is a thin film, a vacuum deposition method, a molecular beam epitaxy (MBE) method, or the like is preferable as a method for forming the thin film. The extraction electrode 3 and the short-circuit electrode 2 are formed by using a vapor deposition method, a sputtering method, a plating method, or the like, and are Cu, Al, Au single layer, or Ti / Au, Ni / Au, Cr / Cu, Cu / Ni. / Au, Ti / Au / Ni, Cr / Au / Ni, Cr / Ni / Au / Ni, Ti / Pt / Au, NiCr / Au, etc. For example, in the case of Ti / Au, Ti is the lower layer and Au is the upper layer. Further, the extraction electrode 3 and the short-circuit electrode 2 do not necessarily have the same electrode structure.

  When the electrode layer is Ti / Au, the diffusion of Au into the compound semiconductor can be reduced by increasing the thickness of the Ti layer, but on the other hand, the resistance value increases and the sensitivity as a magnetoelectric conversion element decreases. Resulting in. In the present invention, the thickness of the electrode layer is not specified, but in the case of an electrode formed in multiple layers, the thickness of the lower layer, for example, the thickness of the Ti layer in the case of Ti / Au is usually 5 to 400 nm. However, it is preferably 10 to 300 nm, and more preferably 10 to 200 nm.

  In general, the material of the protective film that protects the compound semiconductor is preferably an insulating inorganic material. As the protective film, for example, a thin film made of silicon nitride, silicon oxide or the like formed by about 150 to 500 nm by a plasma CVD method or the like is used. In the present invention, the presence, type, and film thickness of the protective film are determined. It is not specified.

  In addition, a soft resin layer is often formed so as to cover the compound semiconductor and the short-circuit electrode for the purpose of relieving pressure and in-plane stress on the compound semiconductor and the electrode due to the mold resin formed outside the element. In general, a silicon-based resin having a thickness of 1 to 300 μm or a rubber-based resin having a thickness of 1 to 10 μm is used for the soft resin layer. In the present invention, the presence / absence, type, and thickness of the soft resin layer are determined. It is not specified.

  Further, when the width obtained by etching the compound semiconductor (the width of the compound semiconductor magnetosensitive portion in the direction orthogonal to the current) is W and the distance between the short-circuit electrodes (element length) is L, L / W is Called form factor. In the present invention, the shape factor L / W is not limited, but L / W = 0.1 to 0.3 is often used. Usually, the width W (the length of the short side of the compound semiconductor) of the compound semiconductor magnetosensitive portion in the direction orthogonal to the current is 5 μm to 500 μm, more preferably 5 μm to 150 μm, and still more preferably 15 μm to 130 μm. is there. In addition, the distance (element length) L between the short-circuit electrodes in the same compound semiconductor magnetosensitive part is usually 0.5 μm to 100 μm, more preferably 0.5 μm to 30 μm, and further preferably 5 μm to 30 μm. .

  The semiconductor element according to the present invention may be a Hall element or a magnetoresistive element.

  Next, a method for producing a magnetoelectric conversion element according to an embodiment of the present invention will be described.

  FIGS. 2A to 2D are diagrams showing a process flow for producing a three-terminal magnetoelectric transducer. A normal photographic technique can be used for the manufacturing process. 3 and 4 are diagrams showing the structure of the junction between the mesa structure of the compound semiconductor and the electrode at the end of the compound semiconductor. More specifically, FIG. 3 shows a structure in which the upper surface of the mesa structure of the compound semiconductor is a plane parallel to the (100) plane, and FIG. 4 shows all orientations.

  As shown in FIG. 2 (a), first, the pattern of the magnetically sensitive portion is exposed and developed on the compound semiconductor, and then mesa-etched into a desired shape with a hydrochloric acid / hydrogen peroxide-based etching solution. A compound semiconductor film 1 is formed on 6. The mesa structure of the compound semiconductor is a zinc blende structure in which a plane parallel to the upper surface of the mesa structure is a (100) plane. The joint surface between the electrode and the long side end of the mesa structure is in a range of −15 ° to + 15 ° with respect to the (111) plane or the plane parallel to the (1-1-1) plane, and (11-1) Pattern formation so that there is no joint in the range of -15 ° to + 15 ° with respect to the plane, (1-11) plane, (-111) plane, and plane parallel to the (-1-1-1) plane Is done. In this embodiment, the compound semiconductor having the (100) plane is described as an example. However, the pattern of the magnetosensitive portion is not limited to the (100) plane, and the junction of the electrode and the compound semiconductor is formed on the equivalent plane. Any magnetoelectric conversion element that has been used may be used. In this case, the joint surface between the electrode and the long side end of the mesa structure is parallel to the (111) plane, the (1-1-1) plane, the (-11-1) plane, or the (−1-11) plane. It is in the range of −15 ° to + 15 ° with respect to at least one of the surfaces.

  The diffusion rate of a metal such as Au constituting the electrode into the compound semiconductor varies depending on the plane orientation, and is a (111) plane, (1-1-1) plane, (-11-1) plane, and (-1- It is slow in the (11) plane, and fast in the (11-1) plane, the (1-11) plane, the (−111) plane, and the (−1-1-1) plane. That is, there is no joint in the range of −15 ° to + 15 ° with respect to the (11-1) plane, the (1-11) plane, the (−111) plane, and the (−1-1-1) plane. By forming a pattern on the surface, characteristic fluctuation can be reduced. The method for forming the pattern of the magnetic sensitive part may be a dry method, or an etching solution other than hydrochloric acid / hydrogen peroxide.

  As shown in FIG. 3, the angle θ formed by the end of the magnetically sensitive portion of the compound semiconductor film and the surface of the compound semiconductor film is usually 90 ° to 150 °. More preferably, it is 90 ° to 135 °, and further preferably 110 ° to 135 °.

  Next, as shown in FIG. 2B, a protective film 4 made of a silicon nitride film is formed on the magnetic sensitive part by plasma CVD.

  Next, as shown in FIG. 2 (c), after removing the protective film 4 in the portion forming the short-circuit electrode 2 using a reactive ion etching apparatus in a range narrower than the portion forming the short-circuit electrode 2, A short-circuit electrode 2 and a take-out electrode 3 are formed.

  Finally, as shown in FIG. 2 (d), the soft resin layer 5 is formed on the magnetosensitive part surface of the magnetoelectric transducer.

  In this manner, a three-terminal magnetoelectric transducer having three terminal electrodes (extraction electrodes) and having a plurality of short-circuit electrodes between the terminal electrodes can be produced by applying photolithography.

  Although the present embodiment has been described using a three-terminal magnetoelectric conversion element, in the present invention, the number of terminals is not specified, and for example, four terminals may be used. The compound semiconductor may be a compound semiconductor having a zinc blende structure and may be bulk. Further, the protective film may be formed after the electrode is formed, and the type of the protective film may not be silicon nitride. The method of removing the protective film may be other dry etching or wet etching methods instead of reactive ion etching. Further, the terminal electrode and the short-circuit electrode may be formed in two portions.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1
First, a Sn-doped InSb thin film was epitaxially grown on a (100) plane of a semi-insulating GaAs single crystal substrate having a thickness of 0.63 mm by using molecular beam epitaxy. The thickness of the deposited InSb was 1 μm, and the electrical properties were measured by a known van der Pauw method. As a result, the electron concentration was 7 × 10 ¹⁶ / cm ³ and the electron mobility was 40000 cm ² / Vs.

  Next, a photoresist was uniformly applied to the surface of InSb formed on the GaAs substrate, exposed and developed, and then mesa-etched with a hydrochloric acid / hydrogen peroxide-based etching solution. At this time, the magnetic sensitive part was formed in a direction in which current flows in the magnetic sensitive part, that is, a direction in which the long side direction of the compound semiconductor magnetic sensitive part is perpendicular to the (011) plane. A silicon nitride thin film having a thickness of 150 nm was formed thereon as a protective film by plasma CVD. Then, after applying a photoresist again, the protective film of the part which forms a short circuit electrode and a taking-out electrode was removed using the reactive ion etching apparatus. Subsequently, a photoresist was applied, exposure and development were performed to form a short-circuit electrode and a take-out electrode, electrodes were deposited by a vacuum evaporation method, and a short-circuit electrode and a take-out electrode were formed by a lift-off method. The electrode thickness was Ti / Au = 50 nm / 450 nm. After forming the first layer of Ti, the second layer of Au was subsequently formed in vacuum. Next, in order to relieve the pressure and in-plane stress due to the mold resin, a rubber-based resin was formed on the surface of the magnetic sensitive part.

  In this way, a plurality of four-terminal magnetoelectric conversion elements having a compound semiconductor film as a magnetic sensing portion, eight rows of semiconductor magnetic sensing portions per element, and a plurality of short-circuit electrodes between the terminal electrodes were manufactured. The distance 7 between the short-circuit electrodes shown in FIG. 5 was 4 μm, and the angle θ formed between the bonding surface of the compound semiconductor film with the electrode at the end of the mesa structure and the surface of the compound semiconductor film was 117 °. The deviation from the (111) plane or the (1-1-1) plane was about 8 °. The direction perpendicular to the current, that is, the width W of the short side of the compound semiconductor magnetic sensing part was 56 μm, and the distance (element length) L between the short-circuit electrodes in the same compound semiconductor magnetic sensitive part was 11 μm.

  Subsequently, the GaAs substrate was polished to a predetermined thickness by backside grinding, adhered to the lead frame with an adhesive, and then molded with a plastic package. In order to evaluate the change in characteristics, a PCT test at 121 ° C. and 2 atm 100% was performed as an acceleration test. A 36-element test was conducted, and the fluctuation amount σ of the midpoint potential was 3.0 mV (applied voltage 5 V) after 300 hours of the test.

(Comparative Example 1)
A magnetoelectric conversion element was produced in the same manner as in Example 1 except that the magnetosensitive part was formed in a direction in which current flows perpendicularly to the (01-1) plane. This corresponds to rotating the compound semiconductor magnetosensitive part of Example 1 by 90 ° on the (100) plane. The angle θ formed between the joint surface of the compound semiconductor film with the electrode at the end of the mesa structure and the surface of the compound semiconductor film was 132 °. The deviation from the (1-11) plane or the (11-1) plane was about 7 °. The electrode thickness was Ti / Au = 50 nm / 450 nm. The direction perpendicular to the current, that is, the width W of the short side of the compound semiconductor magnetic sensing part was 56 μm, and the distance (element length) L between the short-circuit electrodes in the same compound semiconductor magnetic sensitive part was 11 μm. As a result of performing a test similar to the test on the element of Example 1 in order to evaluate the characteristic change of this element, the fluctuation amount σ of the midpoint potential was 16.0 mV (applied voltage 5 V). In Example 1 in which the magnetosensitive part was formed so that the direction of current flow was perpendicular to the (011) plane, the variation σ of the midpoint potential was 3.0 mV (applied voltage 5 V), whereas The amount of fluctuation was large.

(Example 2)
A magnetoelectric transducer was prepared in the same manner as in Example 1 except that the electrode thickness was Ti / Au = 100 nm / 450 nm. The width W of the compound semiconductor magnetosensitive part in the direction orthogonal to the current was 54 μm, and the distance (element length) L between the short-circuit electrodes in the same compound semiconductor magnetosensitive part was 11 μm. As a result of performing a test similar to the test on the element of Example 1 in order to evaluate the characteristic change of this element, the fluctuation amount σ of the midpoint potential is 1.2 mV (applied voltage 5 V), and the fluctuation amount is small and good. It became.

(Example 3)
The width W of the compound semiconductor magnetosensitive part in the direction orthogonal to the current is 120 μm, the distance (element length) L between the shorting electrodes in the same compound semiconductor magnetosensitive part is 24 μm, and the distance 7 between the shorting electrodes is 12 μm. Except that, a magnetoelectric transducer was prepared in the same manner as in Example 2. The electrode thickness was Ti / Au = 100 nm / 450 nm. As a result of performing a test similar to the test on the element of Example 1 in order to evaluate the characteristic change of this element, the fluctuation amount σ of the midpoint potential is 1.3 mV (applied voltage 5 V), and the fluctuation amount is small and good. It became.

Example 4
A magnetoelectric conversion element was produced in the same manner as in Example 3 except that the number of semiconductor magnetic sensing portions was 16 rows. The width W of the compound semiconductor magnetosensitive part in the direction orthogonal to the current is 120 μm, the distance (element length) L between the shorting electrodes in the same compound semiconductor magnetosensitive part is 24 μm, and the distance 7 between the shorting electrodes is 12 μm. Met. The electrode thickness was Ti / Au = 100 nm / 450 nm. In order to evaluate the characteristic change of this element, a test similar to the test on the element of Example 1 was performed. As a result, the fluctuation amount σ of the midpoint potential was 2.3 mV (applied voltage 5 V), and the fluctuation amount was small and good. It was.

  Thus, according to the present invention, it is possible to provide a semiconductor element with small characteristic deterioration. That is, the reliability of the element can be improved by controlling the surface orientation of the joint surface at the joint between the wiring connecting the extraction electrodes and the compound semiconductor.

It is a figure which shows the magnetoelectric conversion element which concerns on one Embodiment of this invention. It is a figure which shows the preparation process flow of the magnetoelectric conversion element which concerns on one Embodiment of this invention. It is a figure which shows the structure of the junction part of the mesa structure of a compound semiconductor and an electrode in the compound semiconductor edge part. It is a figure which shows the structure of the junction part of the mesa structure of a compound semiconductor and an electrode in the compound semiconductor edge part. It is the figure which expanded a part of magnetoelectric conversion element concerning one embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Compound semiconductor film 2 Short electrode 3 Extraction electrode 4 Protective film 5 Soft resin layer 6 Substrate 7 Distance between short electrodes

Claims (7)

A semiconductor device comprising a compound semiconductor film having a mesa structure formed on a substrate, a short-circuit electrode formed on the compound semiconductor film, and an extraction electrode for electrical connection with the outside,
The short-circuit electrode and the extraction electrode are bonded to a mesa portion of the compound semiconductor film,
The bonding surface between the extraction electrode and the long side end of the mesa structure of the compound semiconductor film has a (111) plane, a (1-1-1) plane, a (-11-1) plane, and (-1- 11) It is a range of −15 ° to + 15 ° with respect to at least one of the planes parallel to the plane, and includes (11-1) plane, (1-11) plane, (−111) plane, and ( -1-1-1) A semiconductor element formed so as not to have a junction in a range of -15 ° to + 15 ° with respect to a plane parallel to the plane.   An upper surface of the mesa structure of the compound semiconductor film is a plane parallel to a (100) plane, and the bonding surface between the extraction electrode and the long side end of the mesa structure of the compound semiconductor film is (111) 2. The semiconductor element according to claim 1, wherein the semiconductor element has a range of -15 [deg.] To +15 [deg.] With respect to a plane or a plane parallel to the (1-1-1) plane. The compound semiconductor film is made of In _a Al _b Ga _(1-ab) As _x Sb _(1-x) (0 ≦ a ≦ 1, 0 ≦ b <1, 0 ≦ a + b ≦ 1, 0 ≦ x ≦ 1). The semiconductor element according to claim 1, wherein:   4. The semiconductor device according to claim 1, wherein the short-circuit electrode and the extraction electrode are formed of a single layer or a multilayer made of a single substance of Au or an alloy of Au.   5. The semiconductor element according to claim 1, wherein a lowermost layer of the short-circuit electrode and the extraction electrode is Ti, and a thickness of the Ti is 10 to 200 nm.   6. The semiconductor element according to claim 1, wherein the semiconductor element is a Hall element or a magnetoresistive element.   The length of the short side of the compound semiconductor film is 5 μm to 150 μm, and the distance between the short-circuit electrodes in the same compound semiconductor film is 0.5 μm to 30 μm. A semiconductor device according to claim 1.

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