JP2009059892A - Semiconductor magnetoresistance element and its designing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a magnetoresistance change rate as high as in a case of a conventional large width W even when a width W of a semiconductor operating layer in a direction orthogonal to a length direction of the magnetoresistance element, that is, a direction between electrodes is reduced. <P>SOLUTION: The semiconductor magentoresistance element includes a thin film semiconductor operating layer formed on a substrate, input-output electrodes arranged at least on two end parts on the semiconductor operating layer, and a plurality of short-circuit electrodes arranged at constant intervals in an extending direction of a semiconductor layer extending in a right angle direction with respect to the extending direction of the semiconductor layer extending between the input-output electrodes on the semiconductor operating layer between the input-output electrodes. When the width of the semiconductor operating layer in the right angle direction with respect to the extending direction of the semiconductor layer extending between the input-output electrodes is not more than 60 μm, a length of the short-circuit electrode in the extending direction of the semiconductor layer is not more than 5 μm, the width of the semiconductor operating layer is W, and a distance between the plurality of the short-circuit electrodes at the constant interval is L, L/W which is a ratio of L and W is not more than 0.3. It is preferable that the L/W is not less than 0.1, and the length of the short-circuit electrode is not less than 2 μm. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a magnetic sensor that detects external magnetic field strength, and more particularly to a magnetoresistive element that detects external magnetic field strength and a design method thereof.

  A magnetic sensor that detects the intensity of an external magnetic field is superior to an optical sensor particularly in applications that are affected by dirt, dust, and the like. Typical examples of magnetic sensors include Hall elements and magnetoresistive elements. In general, the magnetoresistive element is used for a sensor for detecting a gear rotation speed, a sensor for detecting a bill magnetic pattern, and the like.

  FIGS. 1A and 1B show one example of the structure of the magnetoresistive element. 1A is a top view and FIG. 1B is a cross-sectional view. Note that these figures are for explanation, and there is no 1: 1 correspondence between FIG. 1 (a) and FIG. 1 (b) in terms of dimensions. In the figure, reference numeral 1 denotes a substrate, reference numeral 2 denotes a semiconductor operation layer, reference numeral 3 denotes an input / output electrode as a magnetoresistive element, and reference numeral 4 denotes a short-circuit electrode. Here, the semiconductor operation layer denoted by reference numeral 2 extends in the inter-electrode direction, and the long-axis direction of the short-circuit electrode is arranged in a form orthogonal to the inter-electrode direction. Symbol L is a distance in a direction parallel to the inter-electrode direction between the short-circuit electrodes, and is also a distance between the input / output electrodes and the short-circuit electrodes. The symbol Le is the length of the short-circuit electrode in the same interelectrode direction, and the symbol W is the width of the semiconductor operation layer in the direction orthogonal to the interelectrode direction (in other words, the direction in which the semiconductor operation layer extends).

  When a magnetic field is applied perpendicular to the magnetosensitive surface of the element (in the case of FIG. 1A, a plane parallel to the paper surface), the horizontal traveling direction of the carrier in the absence of the magnetic field depends on the external magnetic field strength and its direction. Accordingly, the carrier path of the entire element is bent by the Lorentz force (in the case of FIG. 1A, corresponding to the length direction of the short-circuit electrode, upward or downward), and there is no magnetic field. Longer than In general, however, when the bent side reaches the side edge of the semiconductor layer, it is not further bent. This means that if the semiconductor layer is longer than the distance until it reaches the side edge after being bent by the magnetic field, the part beyond that distance is basically less susceptible to the influence of the magnetic field than the bent part. Become. In FIG. 1, for this purpose, the short-circuit electrode 4 is provided at every constant distance in the length direction of the semiconductor layer. The short-circuit electrode 4 has an effect of returning the carrier path bent by the magnetic field, that is, a carrier reset effect. That is, for example, when the carriers collected on the upper part of the semiconductor operation layer in FIG. 1A are theoretically uniformly distributed over the entire short-circuit electrode by the short-circuit electrode 4, that is, when bent upward, A part of it also moves to the lower part of 1 (a). In other words, the relationship between the right end portion of the short-circuit electrode and the semiconductor operation layer on the right side thereof in the drawing is the same as the relationship between the left input / output electrode and the semiconductor operation layer on the right side. By utilizing the reset effect of the carrier density by the short-circuit electrode, it is possible to provide a number of portions where the carriers are bent, that is, it is possible to configure a portion having a high magnetic field detection sensitivity in series. With this configuration, it is possible to obtain a magnetoresistive effect that the resistance between the output terminals increases in accordance with the magnitude of magnetism in a desired impedance range. That is, the magnetoresistive element of FIG. 1 functions as a magnetic sensor, with the element resistance changing according to the magnetic field strength. Theoretically, the smaller the L / W, which is the ratio of the distance L between the short-circuit electrodes and the width W of the semiconductor operation layer, is, the greater the magnetoresistance change rate with respect to the magnetic change.

  In addition, it is considered that the portion where the short-circuit electrode is formed is only effective in resetting the carrier density of the semiconductor magnetoresistive element and does not contribute to the change in magnetoresistance of the element. FIG. 1C shows a typical example of the magnetoresistive effect. It can be seen that the magnetoresistance change rate increases as the external magnetic field strength increases.

FIG. 2 is a diagram showing an equivalent circuit of a pair of semiconductor operation layers and a short-circuit electrode shown in the magnetoresistive element cross section of FIG. Here, R ₁ is a resistance of the semiconductor operation layer that mainly activates the magnetoresistive effect, R ₂ is a resistance of the semiconductor operation layer immediately below the short-circuit electrode, Rm is a resistance of the short-circuit electrode, and Rc is a resistance between the semiconductor operation layer and the short-circuit electrode. Contact resistance.

Hereinafter, the series resistance component of the contact resistance and the short-circuit electrode is Rs, and the parallel resistance component of Rs and R ₂ is Rp. Rs and Rp can be expressed as follows.

Conventionally, in order to obtain a large rate of change in magnetoresistance, it has been considered that the reset effect by the short-circuit electrode is sufficient, that is, it is necessary to cause more carriers to act on the short-circuit electrode. For this purpose, it is necessary to reduce Rs / R ₂ , which is the ratio of Rs to R ₂ , and in particular, the following two methods have been taken to reduce the contact resistance Rc.

  The first is a method of improving the interface state between the semiconductor operating layer and the short-circuit electrode by annealing or implantation. The second method is to increase the length Le of the short-circuit electrode.

Usually, the larger the contact area between the short-circuit electrode and the semiconductor operation layer, the smaller the contact resistance Rc. Therefore, by increasing the length Le of the short-circuit electrode, Rs / R ₂ can be reduced, and more carriers are used as the short-circuit electrode. Can act. Both are implemented in the actual device, and the length Le of the short-circuit electrode when the width W of the semiconductor operation layer is about 100 μm is about several tens of μm. The length Le of the short-circuit electrode is long enough to obtain a carrier reset effect, and it has been considered that the carrier reset effect is larger as the length Le of the short-circuit electrode is larger.

Further, since the magnetoresistance change rate can be expressed as ΔR / {n × (R ₁ + Rp)}, the smaller the Rp that the magnetoresistance effect cannot be expected, the more advantageous the magnetoresistance change rate of the entire magnetoresistive element. Here, ΔR is an increase in element resistance due to the applied magnetic field, and n is the number of pairs of the semiconductor operation layer and the short-circuit electrode. When L / W, which is the ratio of the width W of the semiconductor operation layer to the distance L between the short circuit electrodes, and the length Le of the short circuit electrode are fixed, the contact between the semiconductor operation layer and the short circuit electrode decreases as the width W of the semiconductor operation layer decreases. The area is small, that is, the contact resistance Rc increases, and Rp increases accordingly. That is, when the width W of the semiconductor operation layer is reduced, the magnetoresistance change rate is also reduced.

  As described above, conventionally, as an element structure for obtaining a large magnetoresistance change rate, more carriers are caused to act on the short-circuit electrode having a reset effect, and the ratio of Rp to the total resistance is small. It has been considered necessary that the length Le of the short-circuit electrode is sufficiently large and the width W of the semiconductor operation layer is large.

  The details of the operation principle of the semiconductor magnetoresistive element are introduced in Non-Patent Document 1, for example, and the miniaturization technology of the semiconductor magnetoresistive element is introduced in Patent Document 1, for example.

H. WEISS, translated by Teruaki Kataoka, “Structure and Application of Magnetoelectric Conversion Elements”, Corona, p. 16-22 JP 2001-68755 A

  In order to detect gear rotation with high accuracy using a semiconductor magnetoresistive element, it is necessary to use a gear with a narrow pitch. In general, the pitch P of the gear (the distance between the adjacent crests and crests or the trough and trough of the gear) is defined as P = Mπ (mm) using the module M.

  The smaller the gear of the module M, the smaller the pitch P, and the gear rotation can be detected with high accuracy. For example, M = 2 to 3 is used for railway axle gears with sufficient vehicle position detection accuracy of about 10 cm, and M = 0.4 to 0 .0 for machine tools that require high-precision gear rotation control of several hundred μm or less. 8 is used in combination with the IC, and M = 0.2 is used for those requiring further precise control.

  When the rotation of a gear is detected using a semiconductor magnetoresistive element, the semiconductor magnetoresistive element is usually set to a width of the semiconductor operation layer that is half or less than the pitch P of the gear. That is, the smaller the gear module M, the smaller the width of the semiconductor magnetoresistive element (corresponding to W in FIG. 1A). When M = 0.2 described above, this W is 0.2 × π / 2 = 0.314 mm, that is, 314 μm or less.

  However, since there is an optimal value for the semiconductor magnetoresistive element, that is, L / W, which is the ratio of the distance L between the short-circuited electrodes and the width W of the semiconductor operation layer, it is difficult to understand as the gear pitch becomes narrower. The width W of the semiconductor operation layer cannot be reduced. This is because, for example, when the optimum value of L / W is 0.2 and the width W of the semiconductor operation layer is 10 μm, the distance L between the short-circuit electrodes is 10 μm × 0.2 = 2 μm, which is an advanced technique for fine pattern formation. Cost.

  Further, if the length Le of the semiconductor operation layer is reduced with the length Le of the short-circuited electrode being constant, the ratio of the resistance component Rp having no magnetoresistance effect to the total resistance increases due to the increase of the contact resistance Rc. There was a problem that the rate of resistance change would be small.

FIG. 3 shows an InSb (film thickness: 1 μm, carrier density: 7 × 10 ¹⁶ (/ cm ³ ), electron mobility: 42000 cm ² / Vs) formed on a GaAs substrate. It is the figure which showed the magnetoresistive effect whose width W is 100 micrometers, 60 micrometers, and 30 micrometers. The L / W of the element is a constant value of 0.2, and the length Le of the short-circuit electrode is 10 μm. When the width W of the semiconductor operation layer is changed from 100 μm to 30 μm, the magnetoresistance change rate is reduced from 57% to 43% at an external magnetic field of 0.2 Tesla. This is because the resistance of Rp in the absence of a magnetic field increases as the width W of the semiconductor operation layer decreases and the contact resistance Rc increases, so that ΔR / {n × (R ₁ + Rp)} which is the magnetoresistance change rate is I can understand that it has become smaller.

  As described above, the design of the semiconductor magnetoresistive element having the semiconductor operation layer width W of about 100 μm or less is limited as described above, and also compared with the case where the semiconductor operation layer width W is about 100 μm or more. There was a problem that the performance deteriorated. Accordingly, there has been a demand for a semiconductor magnetoresistive element with little deterioration in performance even when the width W of the semiconductor operation layer is about 100 μm or less.

  The present invention has been made in view of such problems. The object of the present invention is to design a semiconductor magnetoresistive element having a semiconductor operation layer width W of about 100 μm or less based on a conventional design method. Is to provide a high-performance semiconductor magnetoresistive element, and to provide an effective design technique for a semiconductor magnetoresistive element having a semiconductor operating layer width W of about 100 μm or less. In other words, it is an object to provide a semiconductor magnetoresistive element having substantially the same performance or little performance deterioration even when the width W of the semiconductor operation layer is about 100 μm or less.

  In order to achieve such an object, the present invention is arranged in a thin film semiconductor operation layer formed on a substrate and at least two ends on the semiconductor operation layer. In the form extending on the semiconductor operation layer between the input / output electrodes and the semiconductor operation layer between the input / output electrodes in a direction perpendicular to the extending direction of the semiconductor layer extending between the input / output electrodes. In a semiconductor magnetoresistive element having a plurality of short-circuit electrodes arranged at regular intervals in the extending direction, the semiconductor operation layer in a direction perpendicular to the extending direction of the semiconductor layer extending between the input / output electrodes The width of the semiconductor layer is 5 μm or less, the width of the semiconductor operation layer is W, and the distance between the plurality of short-circuited electrodes at a constant interval is 60 μm or less. When L is L, L / W, which is the ratio of L and W, is 0. .3 or less.

  A second aspect of the present invention is the semiconductor magnetoresistive element according to the first aspect, wherein the L / W is 0.1 or more.

  The invention of claim 3 is the semiconductor magnetoresistive element according to claim 1 or 2, wherein the length of the short-circuit electrode is 2 μm or more.

The invention according to claim 4 is the semiconductor magnetoresistive element according to any one of claims 1 to 3, wherein the composition of the semiconductor operation layer is InAs _y Sb _1-y (0 ≦ y ≦ 1). It is characterized by this.

The invention according to claim 5 is the semiconductor magnetoresistive element according to any one of claims 1 to 4, wherein the semiconductor operation layer is doped with a group IV element or a group VI element, and the electron The density is 1 × 10 ¹⁶ to 1 × 10 ¹⁸ (cm ⁻³ ).

  A sixth aspect of the present invention is the semiconductor magnetoresistive element according to any one of the first to fifth aspects, wherein the substrate on which the semiconductor operation layer is formed is Si or GaAs. It is.

  The invention of claim 7 is a method for designing a semiconductor magnetoresistive element, comprising a thin film semiconductor operation layer formed on a substrate, and input / output electrodes disposed at at least two ends on the semiconductor operation layer, And a plurality of short-circuit electrodes arranged on the semiconductor operation layer between the input / output electrodes so as to extend in a direction perpendicular to the extending direction of the semiconductor layer extending between the input / output electrodes. A method for designing a magnetoresistive element, wherein a width of the semiconductor operation layer in a direction perpendicular to an extending direction of the semiconductor layer extending between the input and output electrodes is set to 60 μm or less, and the short-circuit electrode of the semiconductor layer When the length in the extending direction is 5 μm or less, the width of the semiconductor operation layer is W, and the distance between the plurality of short-circuited electrodes at a constant interval is L, L / W as a ratio of L to W is 0. .3 or less.

  The invention of claim 8 is the method of designing a semiconductor magnetoresistive element according to claim 7, wherein the L / W is 0.1 or more.

  The invention of claim 9 is the method of designing a semiconductor magnetoresistive element according to claim 7 or 8, wherein the length of the short-circuit electrode is 2 μm or more.

The invention of claim 10 is the semiconductor magnetoresistive element design method according to any one of claims 7 to 9, wherein the composition of the semiconductor operating layer is InAs _y Sb _1-y (0 ≦ y ≦ 1). ).

The invention of claim 11 is the method of designing a semiconductor magnetoresistive element according to any one of claims 7 to 10, wherein the semiconductor operation layer is doped with a group IV element or a group VI element. The electron density is 1 × 10 ¹⁶ to 1 × 10 ¹⁸ (cm ⁻³ ).

  The invention of claim 12 is the method of designing a semiconductor magnetoresistive element according to any one of claims 7 to 11, wherein the substrate on which the semiconductor operation layer is formed is Si or GaAs. And

  As described above, according to the present invention, it is possible to provide a semiconductor magnetoresistive element having substantially the same performance or little performance deterioration even when the width W of the semiconductor operation layer is about 100 μm or less. .

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol in each figure has shown the same thing or the similar thing.

  The present inventors have attempted to obtain the relationship between the change of each parameter described above and the resulting magnetoresistance effect, aiming at optimization of the element shape using magnetic field simulation. As a result, by designing the length Le of the short-circuit electrode to be short, the width W of the semiconductor operation layer is reduced, that is, even in a magnetoresistive element having a size corresponding to the gear of the smaller module M, the conventional large semiconductor operation It was discovered that the rate of change in magnetoresistance as high as the layer width W can be maintained.

  As described in the background art, in order to obtain a large rate of change in magnetoresistance, it is necessary to reduce Rp where the magnetoresistance effect cannot be expected.

FIG. 4 shows the calculation result of the short-circuit electrode length dependency of Rp (resistance of the portion including the short-circuit electrode serving as a series resistance component as a magnetoresistive element) in the absence of a magnetic field when the width W of the semiconductor operation layer is 125 μm. FIG. Here, 0.058Ω was used as the sheet resistance of the electrode, 0.3Ω was used as the contact resistance value Rc when the area where the semiconductor operating layer was in contact with the short-circuit electrode was 1250 μm ² , and 20Ω was used as the sheet resistance of the semiconductor operating layer. The contact resistance Rc is assumed to be inversely proportional to the area where the semiconductor operating layer and the short-circuit electrode are in contact. That is, if the length Le of the short-circuit electrode is large, the contact resistance Rc is small.

In FIG. 4, in the region where the length Le of the short-circuit electrode is 7 μm or more, the contact area between the short-circuit electrode and the semiconductor operation layer increases, so that the contact resistance Rc decreases and the resistance value of Rp decreases. A conventional semiconductor magnetoresistive element uses this region. The relationship between the resistance values in this region is R ₂ > Rs.

On the other hand, the resistance value of Rp is small even in the region where the length Le of the short-circuit electrode is 7 μm or less. This is because the contact resistance Rc increases as the length Le of the short-circuit electrode decreases, but at the same time, the semiconductor operating layer resistance R ₂ immediately below the short-circuit electrode decreases, and the magnitude relationship between R ₂ and Rs is reversed. That is, it is shown that R ₂ <Rs.

  Conventionally, it has been considered that the carrier does not act on the short-circuited electrode with a small length of the short-circuited electrode and a reset effect cannot be expected. Therefore, this region (the length Le of the short-circuited electrode is 7 μm or less) has not been used. Conventionally, since it was assumed that carriers act on the short-circuit electrode, it has been considered that the magnetoresistance effect of Rp cannot be expected.

However, considering from the result of FIG. 4 mentioned above, the carrier is the starts to act on the R _2, R ₂ is Rp would also be to trigger the magnetoresistance effect exhibits a magnetoresistance effect.

Based on the above, the L / W dependency of the magnetoresistance change rate when the width W of the semiconductor operation layer is 125 μm, 60 μm, and 30 μm and the length Le of the short-circuit electrode is 10 μm, 5 μm, and 2 μm was calculated. The external magnetic field strength was 0.2 Tesla, and the electron mobility was 42000 cm ² / Vs. FIG. 5A is a diagram showing the L / W dependency of the magnetoresistance change rate when the width W of the semiconductor operation layer is 125 μm. FIG. 5B is a diagram similarly showing the L / W dependency of the magnetoresistance change rate when the width W of the semiconductor operation layer is 60 μm. FIG. 5C is also a diagram showing the L / W dependency of the magnetoresistance change rate when the width W of the semiconductor operation layer is 30 μm. In FIG. 5A, circles, diamonds, and triangles are measured values of actual devices. As shown in FIG. 5A, it can be seen that there is a correlation between the calculation of the magnetic field simulation and the actual measurement value.

  The following is understood from FIG. Regardless of the width W of the semiconductor operation layer, the increase width of the magnetoresistance change rate increases as the length Le of the short-circuit electrode decreases. In particular, when the width W of the semiconductor operation layer is small, the increase width is large. When L / W = 0.2, the length Le of the short-circuit electrode is changed from 10 μm to 2 μm in the case of 125 μm. While the rate of change is only a slight increase from 57.2% to 62.3%, in the case of 30 μm, the increase is from 45.6% to 61.8%.

The magnetoresistance ratio decreases with a smaller L / W, the injection resistance increase rate [Delta] R ₁ / R ₁ of R ₁ by the magnetic field is increased, R ₁ is reduced in accordance with short-circuit distance L between electrodes is small, It is considered that the resistance balance between R ₁ and Rp in the absence of a magnetic field is lost, and the ratio of Rp to the total resistance increases, that is, n × Rp / {n × (R ₁ + Rp)} increases. . Here, ΔR ₁ is a resistance increasing component of R ₁ due to the applied magnetic field.

  FIGS. 6A, 6B, and 6C are diagrams in which the same data used in FIG. 5 is rearranged by the length Le of the short-circuit electrode. From this figure, it can be seen that if the length Le of the short-circuit electrode is short, the decrease in magnetoresistance change rate is smaller than that when the length Le of the short-circuit electrode is 10 μm even if the width W of the semiconductor operation layer is small. .

  5A, 5B, and 5C, the magnetoresistive effect is increased regardless of the width W of the semiconductor operation layer by reducing the length Le of the short-circuit electrode from the conventional 10 μm. The effect can be confirmed at least from 2 μm to 5 μm.

  Further, the smaller the width W of the semiconductor operation layer, the larger the increase in the magnetoresistance change rate with respect to the decrease in the length Le of the short-circuit electrode, and the effect can be confirmed at least from 30 μm to 60 μm.

  From the above, it can be understood that the smaller the L / W, the greater the magnetoresistive effect. However, in the actual device, L / W is about 0.1 to 0.3 because of the mass productivity of the element and the stability of characteristics. in use. For example, when L / W = 0.01, even if the width W of the semiconductor operation layer is 125 μm, the distance L between the short-circuit electrodes is 125 × 0.01 = 1.25 μm, and a margin for forming the short-circuit electrodes Becomes very small.

  In mass production, L / W changes by the margin of the distance L between the short-circuit electrodes and the width W of the semiconductor operation layer, and as a result, the magnetoresistance change rate also changes. It is necessary to set L / W in a region where is small.

  In the magnetoresistive element according to the present invention, it can be seen that the effect of reducing the length Le of the short-circuit electrode is particularly effective when the width W of the semiconductor operation layer is small. That is, by using the present invention to reduce the length Le of the short-circuit electrode, the width W of the semiconductor operation layer is reduced, that is, even in the element corresponding to the small module M, the width W of the conventional large semiconductor operation layer is reduced. High magnetoresistance change rate can be realized.

  Embodiments of the present invention will be described below with reference to the drawings.

  7A and 7B are views for explaining the structure of an embodiment of the magnetoresistive element of the present invention. FIG. 7A is a top view of the entire element, and FIG. It is sectional drawing in AA in 7 (a). In the figure, reference numeral 5 is a substrate, reference numeral 6 is a semiconductor operation layer, reference numeral 7 is an input / output electrode, and reference numeral 8 is a short-circuit electrode. The semiconductor operation layer 6 used in the present invention preferably has as high an electron mobility as possible in order to obtain a high magnetoresistance change rate. In addition to Si and GaAs semiconductors, InSb, InAs, and their InAsSb, which is a mixed crystal system, is particularly preferable.

  The substrate 5 used in the present invention may be any substrate as long as it exhibits a solid shape. For example, a semiconductor, a dielectric, a ceramic, or a glass substrate can be used. Alternatively, the semiconductor operation layer 6 may be formed on a flexible substrate 5 such as mica and transferred onto another substrate. Moreover, when a substrate such as GaAs, Si, InP, or GaP is used among the semiconductor substrates, high electron mobility can be obtained particularly by epitaxially growing the semiconductor operation layer 6, which is particularly preferable.

FIG. 8 is a diagram showing a case where the buffer layer 9 is inserted between the substrate 5 and the semiconductor operation layer 6. In order to further increase the electron mobility of the semiconductor operation layer 6, the configuration shown in FIG. In this case, the buffer layer 9 may be a semiconductor or a dielectric, SiO ₂ , Si ₃ N ₄ or the like is used as the dielectric, and a semiconductor having a lattice constant as close as possible to the semiconductor operation layer 6 may be selected. Preferably, a binary system such as GaAs, InAs, GaSb, and AlSb, a ternary system such as InGaAs, GaAsSb, AlAsSb, and AlInSb, and a quaternary system such as AlGaAsSb may be used. Further, it is a more preferable form that the above-described materials are alternately laminated to form a superlattice structure.

  As a method of adding impurities for increasing carriers in the semiconductor operation layer 6 in the present invention, it may be performed simultaneously with the formation of the semiconductor operation layer 6, but it is implanted using an ion implantation method after film formation. But it ’s okay. For example, in the case of a III-V group compound semiconductor such as InSb or InAs, the impurities used may be a group IV element such as Si or Sn, or a group VI element typified by Se, Te, or S. .

Adding impurities for increasing carriers in the semiconductor operation layer 6 has an effect of improving the temperature characteristics of the manufactured magnetoresistive element. However, if too much impurities are added, the magnetoresistive element Since there is a problem that the carrier mobility that affects the sensitivity is lowered, the number of added carriers is preferably 1 × 10 ¹⁶ / cm ³ to 1 × 10 ¹⁸ / cm ^3, and more preferably, It is good to set it as 1 * 10 < ¹⁶ > / cm < ³ > to 3 * 10 < ¹⁷ > / cm < ³ >.

  As a method for forming the semiconductor operation layer 6 and the buffer layer 9 in the present invention, a vacuum deposition method is generally used. However, the molecular beam epitaxy (MBE) method has a particularly high controllability of the film thickness and composition of the thin film. This is the preferred method.

  The electrode material used for the input / output electrode 7 and the short-circuit electrode 8 in the present invention is a Cu single layer, Ti / Au, Ti / Pt / Au, Ni / Au, Ni / Pt / Au, Cu / Pt / Au, Cu A laminate such as / Ni / Au may be used. This electrode material may be any material as long as it can withstand the operating conditions and environmental conditions in which the manufactured element is used.

  In addition, as a method for forming the electrode, the electrode may be formed by a general vacuum deposition method such as electron beam deposition or resistance heating deposition, a sputtering method, or a plating method. In order to improve the ohmic contact between the electrode and the semiconductor operation layer after the electrode is formed, it is also preferable to perform a heat treatment using a rapid temperature rise annealing (RTA) method or the like.

FIG. 9 is a diagram showing a structural example for improving the environmental resistance of the element. After the protective film 10 such as Si ₃ N ₄ or SiO ₂ is formed, the protective film can be opened only at necessary portions to form short-circuit electrodes and input / output electrodes.

  Hereinafter, the present invention will be described with reference to specific examples of a method for manufacturing a magnetoresistive element, but the present invention is not limited to these examples.

(Example 1)
The details of forming a Sn-doped InSb thin film as a semiconductor operating layer on a GaAs substrate using molecular beam epitaxy as an example of the thin film forming method will be described. First, the surface oxygen is desorbed by heating at 650 ° C. while irradiating the GaAs substrate with As. Next, the temperature is lowered to 580 ° C. to form a GaAs buffer layer with a thickness of 200 nm. Next, the temperature was lowered to 400 ° C. while irradiating As, and then a Sn-doped InSb thin film having a semiconductor operating layer thickness of 1 μm was formed while simultaneously irradiating the substrate with Sn, In, and Sb. At this time, the Sn cell temperature was adjusted so that the electron mobility of the InSb thin film was 7 × 10 ¹⁶ / cm ³ .

  As a manufacturing process of the magnetoresistive element, a normal photolithography technique can be used. First, a photoresist is uniformly applied to the InSb surface of the InSb / GaAs substrate using a spin coater. The photoresist coating condition is 2.5 μm when rotated for 20 seconds at a rotational speed of 3200 rpm with a viscosity of 100 cp. Using a photomask for InSb mesa etching, after exposure and development, the InSb thin film is mesa-etched into a desired shape with a hydrochloric acid / hydrogen peroxide-based etching solution. In the case of wet etching, since there is an influence of side etching, the width W of the semiconductor operation layer that can be manufactured practically with good control is about 10 μm.

  In this case, the example in which the semiconductor operation layer is etched using the wet etching method has been introduced. However, the mesa etching may be performed by dry milling using ion milling or reactive ion etching. In the case of dry etching, since the amount of side etching is small, the width W of the semiconductor operation layer can be reduced to about 3 μm.

  Next, after applying a photoresist again, exposure and development for forming a short-circuit electrode and an input / output electrode are performed, an electrode is deposited by a vacuum deposition method, and an electrode is formed by a lift-off method. In the electrode forming step, the short-circuit electrode and the input / output electrode may be formed at once, or may be divided into two steps.

  After forming a resist pattern for forming an electrode with a photoresist, a laminated electrode made of 50 nm thick Ti and 400 nm thick Au is formed as an electrode by an electron beam evaporation method, and a desired electrode shape is formed using a lift-off method Thus, the element shape was completed. At this time, the width W of the semiconductor operation layer is 30 μm, the length Le of the short circuit electrode is 2 μm, and the short circuit electrode interval L is 3 μm, 4.5 μm, 6 μm, 7.5 μm, 9 μm, and 12 μm. did. Since the exposure apparatus used in this embodiment is of the same size exposure type, the length Le of the short-circuit electrode is limited to fine processing of about 1 μm, but if a stepper or the like is used, it can be formed up to about 0.1 μm.

  FIG. 10 shows the L / W dependence of the magnetoresistance change rate at an external magnetic field strength of 0.2 Tesla by measuring the external magnetic field strength of the magnetoresistive element-resistance between the element terminals after completion of these elements. FIG.

(Comparative Example 1)
FIG. 11 shows the external magnetic field strength of the magnetoresistive element with the length Le of the short-circuit electrode set to 5 μm when the magnetoresistive element is manufactured using the same method as in Example 1, and the resistance characteristic between the element terminals. It is a figure which shows the change of the magnetoresistive change rate with respect to L / W at the time of measuring and adding the magnetoresistive change rate when an external magnetic field intensity | strength is 0.2 Tesla to the result of Example 1. FIG.

In Comparative Example 1, since Rp was increased by setting the length Le of the short-circuit electrode to 10 μm and 5 μm, the magnetoresistance change rate ΔR / {n × (R ₁ + Rp)} with respect to the external magnetic field of the magnetoresistive element was small. It is thought that it became. Further, when the length Le of the short-circuit electrode is reduced, the characteristics are improved without depending on L / W.

  Further, when the length Le of the short-circuit electrode is 10 μm and 5 μm, the rate of change in magnetoresistance is lower when L / W is 0.1 than when 0.2, but the length of the short-circuit electrode When the length Le is 2 μm, the L / W continues to rise even when it approaches 0.4 to 0.1.

  Therefore, under this condition, this figure shows that when L / W is in the range of 0.1 to 0.4, Le is 2 μm, which shows good characteristics. This tendency is from L / W from 0.4. It can be seen that the magnetoresistive change rate improves as the value becomes 0.1.

(Comparative Example 2)
FIG. 12 shows the external magnetic field strength of the magnetoresistive element with the width W of the semiconductor operating layer being set to 60 μm and 125 μm when the magnetoresistive element is manufactured using the same method as in Example 1, and the resistance characteristics between the element terminals. It is a figure which shows the change of the magnetoresistive change rate with respect to L / W at the time of measuring and adding the magnetoresistive change rate when the external magnetic field strength is 0.2 Tesla to the result of Example 1. Similarly, FIG. 13 shows the external magnetic field strength of the magnetoresistive element in which the length Le of the short-circuiting electrode is 10 μm and the width W of the semiconductor operation layer is 30 μm, 60 μm, and 125 μm, and the resistance between the element terminals in the method of Example 1. It is a figure which shows the change of the magnetoresistive change rate with respect to L / W when the characteristic is measured and the external magnetic field strength is 0.2 Tesla.

  When the length Le of the short-circuit electrode is 10 μm, the rate of change in magnetoresistance when the width W of the semiconductor operation layer is reduced is significantly reduced (FIG. 13), but the element with the length Le of the short-circuit electrode is 2 μm Almost no decrease (FIG. 12).

  From the above Comparative Examples 1 and 2, it can be seen that the effect of reducing the length Le of the short-circuit electrode is particularly effective when the width W of the semiconductor operation layer is small. In other words, by reducing the length Le of the short-circuit electrode, the width W of the semiconductor operation layer is reduced, that is, even in an element corresponding to the small module M, the magnetic field is as high as the width W of the conventional large semiconductor operation layer. A rate of change in resistance can be realized.

(A) is a figure which shows the top view of the structural example of a semiconductor magnetoresistive element, (b) is a figure which shows sectional drawing of the structural example of a semiconductor magnetoresistive element, (c) is a figure which shows the magnetism of a semiconductor magnetoresistive element. It is a figure which shows the typical example of a resistance effect. It is a figure which shows the equivalent circuit of a pair of semiconductor operation | movement layer and short circuit electrode in the magnetoresistive element of FIG.1 (b). It is a figure which shows an example of the relationship between an external magnetic field strength and a magnetoresistive change rate in case the width W of a semiconductor operation layer is 100 micrometers, 60 micrometers, and 30 micrometers. It is a figure which shows the calculation result of the length dependence of Rp (resistance of the part containing the short circuit electrode used as a serial resistance component as a magnetoresistive element) in the non-magnetic field in case the width W of a semiconductor operation layer is 125 micrometers. . (A) is the figure which computed the L / W dependence of the magnetoresistive change rate when the width W of a semiconductor operation layer is 125 micrometers and the length Le of a short circuit electrode is 10 micrometers, 5 micrometers, and 2 micrometers, (b) It is the figure which computed the L / W dependence of the magnetoresistive change rate when the width W of a semiconductor operation layer is 60 micrometers and the length Le of a short circuit electrode is 10 micrometers, 5 micrometers, and 2 micrometers, (c) is a figure of (c) It is the figure which computed the L / W dependence of the magnetoresistive change rate when width W is 30 micrometers and length Le of a short circuit electrode is 10 micrometers, 5 micrometers, and 2 micrometers. (A) is the figure which summarized the same data used in FIG. 5 only when the length Le of the short-circuit electrode is 10 μm, and (b) is the same data used in FIG. FIG. 6C is a diagram in which the same data used in FIG. 5 is rearranged only when the length Le of the short-circuit electrode is 2 μm. Calculation result of magnetoresistance effect (A) is a figure explaining the top view of the structure of one Example of this invention, (b) is a figure explaining sectional drawing of the structure of one Example of this invention. It is a figure explaining sectional drawing of the structure of one Example of this invention which inserted the buffer layer. It is a figure explaining sectional drawing of the structure of one Example of this invention which formed the short circuit electrode and the input-output electrode in the opening part of the protective film. It is a figure which shows the L / W dependence of the magnetoresistive change rate when the width W of a semiconductor operation layer is 30 micrometers and the length Le of a short circuit electrode is 2 micrometers using this invention. It is the figure which added the case where length Le of a short circuit electrode is 10 micrometers and 5 micrometers in FIG. FIG. 10 is a diagram when the case where the width W of the semiconductor operation layer is 60 μm and 125 μm is added to FIG. 10. It is a figure which shows the L / W dependence of the magnetoresistive change rate in the conventional structure, ie, when Le is 10 micrometers and the width W of a semiconductor operation layer is 30 micrometers, 60 micrometers, and 125 micrometers.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Semiconductor operation layer 3 Input / output electrode 4 Short-circuit electrode 5 Substrate 6 Semiconductor operation layer 7 Input / output electrode 8 Short-circuit electrode 9 Buffer layer 10 Protective film

Claims (12)

A thin film semiconductor operating layer formed on the substrate;
Input / output electrodes disposed at at least two ends on the semiconductor operation layer;
On the semiconductor operation layer between the input / output electrodes, the semiconductor layer extending between the input / output electrodes extends in a direction perpendicular to the extending direction of the semiconductor layer, and is spaced at a constant interval in the extending direction of the semiconductor layer. In a semiconductor magnetoresistive element having a plurality of short-circuit electrodes arranged,
The width of the semiconductor operation layer in the direction perpendicular to the extending direction of the semiconductor layer extending between the input / output electrodes is 60 μm or less;
The length of the short circuit electrode in the extending direction of the semiconductor layer is 5 μm or less,
L / W, which is a ratio of L to W, is 0.3 or less, where W is the width of the semiconductor operation layer, and L is the distance between the plurality of short-circuited electrodes at regular intervals. Magnetoresistive element.   2. The semiconductor magnetoresistive element according to claim 1, wherein the L / W is 0.1 or more.   The length of the said short circuit electrode is 2 micrometers or more, The semiconductor magnetoresistive element of Claim 1 or 2 characterized by the above-mentioned. 4. The semiconductor magnetoresistive element according to claim 1, wherein the composition of the semiconductor operation layer is InAs _y Sb _1-y (0 ≦ y ≦ 1). 5. 5. The semiconductor operating layer is doped with a group IV element or a group VI element, and the electron density thereof is 1 × 10 ¹⁶ to 1 × 10 ¹⁸ (cm ⁻³ ). The semiconductor magnetoresistive element according to any of the above.   6. The semiconductor magnetoresistive element according to claim 1, wherein the substrate on which the semiconductor operation layer is formed is Si or GaAs. A thin film semiconductor operating layer formed on the substrate;
Input / output electrodes disposed at at least two ends on the semiconductor operation layer;
A plurality of short-circuit electrodes arranged on the semiconductor operation layer between the input / output electrodes and extending in a direction perpendicular to the extending direction of the semiconductor layer extending between the input / output electrodes. A resistance element design method comprising:
The width of the semiconductor operation layer in the direction perpendicular to the extending direction of the semiconductor layer extending between the input / output electrodes is 60 μm or less,
The length of the short-circuit electrode in the extending direction of the semiconductor layer is 5 μm or less,
L / W, which is a ratio of L to W, is 0.3 or less, where W is the width of the semiconductor operation layer, and L is the distance between the plurality of short-circuited electrodes at regular intervals. Design method of magnetoresistive element.   8. The method of designing a semiconductor magnetoresistive element according to claim 7, wherein the L / W is 0.1 or more.   9. The method of designing a semiconductor magnetoresistive element according to claim 7, wherein the length of the short-circuit electrode is 2 [mu] m or more. 10. The method of designing a semiconductor magnetoresistive element according to claim 7, wherein the composition of the semiconductor operation layer is InAs _y Sb _1-y (0 ≦ y ≦ 1). 11. The semiconductor operating layer is doped with a group IV element or a group VI element, and an electron density thereof is 1 × 10 ¹⁶ to 1 × 10 ¹⁸ (cm ⁻³ ). A method for designing a semiconductor magnetoresistive element according to any one of the above.   12. The method of designing a semiconductor magnetoresistive element according to claim 7, wherein the substrate on which the semiconductor operation layer is formed is Si or GaAs.

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