JP2005142476A - Semiconductor device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device by which a variation in characteristics in a range from an microwave band to a terahertz band is suppressed, mounting is easy, and a high-frequency signal is efficiently transmitted to space or an external circuit. <P>SOLUTION: The semiconductor device 100 includes a substrate 1 having a transistor region Rt and an oscillating element region Rg, a bipolar transistor 100t formed on the transistor region Rt of the substrate 1, and a Gunn diode 100g formed on the oscillating element region Rg of the substrate 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a semiconductor device that operates in a microwave band, a millimeter wave band, and a terahertz frequency band.

  In recent years, technological progress in the information communication field has been remarkable, and the frequency band handled by communication equipment has also changed from a microwave band to a millimeter wave band to a higher frequency band. In such communication circuits that handle high frequency bands from the microwave band to the millimeter wave band, a low-loss transmission line, an oscillation circuit or an oscillation element that generates a high-frequency signal, and an active element (transistor) that has an amplification function A nonlinear element (mixer) that mixes the signal and the carrier wave is an important circuit component.

  Conventionally, as a transistor used for an application requiring a frequency band from the microwave band to the millimeter wave band, a heterojunction bipolar transistor (HBT) using a compound semiconductor, a heterojunction field effect transistor (HFET) (or a high-frequency transistor) is used. A mobility field effect transistor (HEMT) is used. One index indicating the high-frequency operation limit of these transistors is the current gain cutoff frequency ft at which the current amplification factor is 1, and the value of ft of an element currently developed for high-frequency applications is reported to be about 200 GHz to 400 GHz. Yes. Furthermore, the maximum oscillation frequency fmax (frequency at which the power gain becomes 1), which is another index indicating high frequency characteristics, is also reported to be about 200 GHz to 400 GHz, and these transistors may be operable up to about 400 GHz. It is shown. In many cases, a Schottky diode using a compound semiconductor or a non-linear operation of a transistor as described above is used as a mixer for realizing frequency mixing.

  Conventionally, in order to generate a high-frequency signal in the microwave band, an oscillation circuit in which a positive feedback is applied to a high-frequency amplifier or a two-terminal element having a negative resistance characteristic is used. Among these, the output of the oscillation circuit that applies positive feedback to the high-frequency amplifier may deteriorate the frequency characteristics of the high-frequency amplifier from the millimeter wave band to the high-frequency band, and a sufficient output may not be obtained. For this reason, two-terminal elements exhibiting negative resistance characteristics are frequently used at frequencies above the millimeter wave band.

  Typical examples of the two-terminal element exhibiting negative resistance characteristics include a Gunn diode using a gun effect, an IMPATT diode using an avalanche phenomenon of electrons, and a tunnel diode using negative resistance characteristics. Among them, the Gunn diode is useful because it has a relatively simple structure and a relatively large output.

  Many of the circuit elements constituting the communication circuit handling the high frequency band as described above use a compound semiconductor. At present, these circuit elements, for example, a semiconductor device in which a Gunn diode using a Gun effect and an HBT are integrated on a GaAs substrate (see Patent Document 1), and an HBT and an HFET (HEMT) on a GaAs substrate. A semiconductor device (see Patent Document 2) and the like integrated with each other has also been developed.

  A Gunn diode is a diode that utilizes the Gunn effect. The gun effect is a state in which the mobility is high when the traveling speed of electrons has an electric field dependency and the electric field strength is smaller than the critical value Eth in a direct transition type n-type semiconductor having a zinc flash structure. On the other hand, when the electric field strength becomes larger than the critical value Eth, this is an effect that occurs because the mobility shifts to a low state. Here, the principle of generating the gun effect will be described with reference to FIGS. FIG. 18 is a diagram schematically showing the principle of generating a gun effect in a planar type Gunn diode, and FIG. 19 shows the relationship between electric field strength and electron traveling speed in a Gunn diode using n-type GaAs. It is a figure (refer nonpatent literature 1). In FIG. 19, the horizontal axis represents the electric field strength, and the vertical axis represents the traveling speed of electrons.

  As shown in FIG. 18, the planar type Gunn diode includes an n-type semiconductor layer 102 that is formed on the uppermost portion of the substrate 101 and generates the above-described gun effect, and a pair of electrodes 103 that are formed on the n-type semiconductor layer 102. It consists of. In this Gunn diode, when an electric field larger than Eth is applied from the pair of electrodes 103 to the n-type semiconductor layer 102 causing the above-described Gun effect, the dependence of the traveling speed of electrons on the electric field strength (see FIG. 19). Distribution) occurs in the traveling speed of electrons in the n-type semiconductor layer 102. As a result, an electric field distribution is generated in the n-type semiconductor layer 102, and a region (domain) 104 with a high electron concentration is generated in the n-type semiconductor layer 102. When the domain 104 reaches one electrode 103, a current peak is generated, and this domain 104 is repeatedly generated and travels. As a result, a high-frequency signal is generated according to the period in which the domain 104 reaches one electrode 103. Note that the velocity Vd (cm / s) of the domain 104 coincides with the traveling velocity of electrons saturated at a sufficiently large electric field strength.

  There are several modes for forming the domain 104, and a typical one is a dipole mode in which the domain 104 is generated in one place in the n-type semiconductor layer 102. The maximum frequency f0 of the high-frequency signal generated in the dipole mode is determined by the distance L (cm) between the electrodes 103 and the domain moving speed Vd (cm / s), and is represented by the following formula (1).

f0 = Vd / L (Hz) (1)
Furthermore, in the gun effect, there is a higher-order mode (hybrid mode) in which a plurality of domains 104 are simultaneously generated. It has been estimated that the frequency f of the high frequency signal generated in the hybrid mode is experimentally represented by the following expression (2).

f0 <f <(50 × f0) (2)
Further, as a distance L (cm) between the impurity concentration N ₀ (cm ⁻³ ) of the n-type semiconductor layer 102 and the electrode 103, satisfying the following formula (3) is a condition for generating a gun effect (non-contained) (See Patent Document 1).

N ₀ L> 10 ¹² (cm ⁻² ) (3)
The condition shown in Equation (3) is indicated by the shaded area in FIG. FIG. 20 is a diagram illustrating conditions under which the cancer effect occurs.

Usually, Vd is 10 ¹⁶ to 10 ¹⁸ (cm / s), and using the value of Vd, it is possible to estimate the doping concentration of an impurity causing a gun effect with respect to the distance L between the electrode 103 and FIG.

  Further, the condition for generating the gun effect in the hybrid mode is expressed by the following formula (4) on the premise that a higher electric field is applied than in the dipole mode.

5 × 10 ¹³ > N ₀ L> 10 ¹² (cm ⁻² ) (4)
The condition shown in Expression (4) is indicated by a region R in FIG. Since the impurity concentration N ₀ of the n-type semiconductor layer 102 is usually about 1 × 10 ¹⁶ to 1 × 10 ¹⁸ (cm ⁻³ ), the distance L between the electrodes 103 is 0.1 μm or more from FIG. It can be seen that the cancer effect occurs.

FIG. 21 shows f0 in the most basic dipole mode. From FIG. 21, it is possible to estimate the transmission frequency f0 in the dipole mode with respect to the distance L between the electrodes 3, assuming the value of the velocity Vd of the domain 104. In FIG. 21, based on the fact that Vd is normally 1 × 10 ¹⁶ to 1 × 10 ¹⁸ (cm / s), values close to the actual saturation electron velocity (1 × 10 ⁵ , 1 × 10 ⁶ , 1 × 10 ^7). 1 × 10 ⁸ (cm / s)).

In FIG. 21, the oscillation frequency f0 in the dipole mode is shown. Since the maximum operating frequency f in the hybrid mode can be up to about 50 times f0, for example, Vd = 10 ⁷ (cm / s), L = 5 (μm), about 1 THz oscillation (f0 = 20 GHz), and Vd = 10 ⁷ (cm / s) and L = 2.5 (μm), about 3 THz oscillation ( It can be seen that f0 = 50 GHz) is possible. Furthermore, operation at a higher frequency is expected by using a material having a large Vd or by shortening L.

  Conventionally, a bulk type Gunn diode as shown in Patent Document 3 and Patent Document 4 below is often mounted on a cylindrical case called a pill type package as shown in Patent Document 5 below. The pill type package is designed for a three-dimensional circuit application such as being arranged in a waveguide, and is not very suitable for planar mounting. Further, it may be necessary to bring the rod into contact with the electrode portion of the package in order to extract the high-frequency signal to the outside, which is not very suitable for integration. Furthermore, since the three-dimensional shape of the pill package is comparable to the wavelength of the terahertz band, it may be difficult to obtain a high frequency output in the terahertz band.

  On the other hand, a Gunn diode that can be flip-chip mounted as a configuration that can be mounted in a plane is shown in Patent Document 5 below. An example in which the Gunn diode is flip-chip mounted on a flat circuit board constituting a microstrip line will be described with reference to FIG.

  As shown in FIG. 22, a signal electrode 132 is formed on the surface of the semi-insulating flat substrate 131, and a ground electrode 133 is formed on the back surface. In addition, a via hole 134 is provided in the flat substrate 131 and penetrates the flat substrate 131 to connect the ground electrode 133 on the back surface and the surface ground electrode 135 formed on the front surface to each other. Filled with tungsten.

  Further, the Gunn diode 110A is mounted on the flat substrate 131 in a face-down posture, and the cathode bump and the anode bump of the Gunn diode 110A are directly connected to the signal electrode 132 and the surface ground electrode 135, respectively.

The signal electrode 132 includes a bias electrode 132A that supplies a bias voltage to the Gunn diode 110A, an electrode 132B that forms a resonator using a microstrip line including the Gunn diode 110A, and a signal output electrode 132C that forms the microstrip line. Has been.
JP 2001-210722 A JP-A-2-69943 JP-A-6-314802 (FIG. 1) Japanese Unexamined Patent Publication No. 7-111348 (FIG. 3) Japanese Patent Laid-Open No. 2002-134810 (FIGS. 1, 3, and 9) W. Alan Davis, Microwave Semiconductor Circuit Design, Chapter 15, Van Nostrand Reinhold Company Inc., New York 1984.

  In order to reduce the size of semiconductor devices that operate in the microwave band, millimeter wave band, and terahertz frequency band, multiple elements such as transistors, oscillators, mixers, and transmission lines that make up the semiconductor device are mounted on the same substrate. It is conceivable to integrate them.

  Usually, a semiconductor device using a compound semiconductor is desired to have a structure in which each element constituting the semiconductor device is formed by stacking epitaxial films. Furthermore, in a semiconductor device using a compound semiconductor, it is desired to configure a circuit that couples an oscillation element and a transistor with as low a loss as possible for practical use. In particular, a Gunn diode that can operate in the terahertz region as an oscillating element and obtains a relatively large output is used as an oscillating element, and a transistor or a HBT or HFET (HEMT) as a mixer is arranged close to the oscillating element. It is hoped to do.

  On the other hand, as described above, the Gunn diode mounted on the plane is actually premised on flip chip mounting. At this time, in order to use the Gunn diode in the circuit of the terahertz band, the tolerance of accuracy variation when mounting the Gunn diode is approximately the same as the wavelength of the target frequency (300 μm at 3 THz).

  However, in flip-chip mounting, it is very difficult to mount a Gunn diode with the above-mentioned accuracy, and it is difficult to suppress variations in characteristics in the terahertz band of a product mounting the Gunn diode.

  Further, signal transmission loss is large from the millimeter wave band to the terahertz band. For this reason, it is desirable to shorten the transmission line length as much as possible. In order to shorten the transmission line length, it is necessary to make the circuit smaller and further integrate the circuit elements. However, both pill package and flip chip mounting applied to conventional Gunn diodes will require further integration. It is difficult to realize.

  The present invention has been made in view of such points, and variation in characteristics from the microwave band to the terahertz band is suppressed, mounting is easy, and high-frequency signals are efficiently transmitted to space and external circuits. An object of the present invention is to provide a semiconductor device capable of performing

  A semiconductor device of the present invention includes a substrate having an oscillation element region and a transistor region, an oscillation element formed on the oscillation element region, and a transistor formed in the transistor region.

  According to the present invention, the transistor and the oscillation element are mounted on the same substrate without using flip chip mounting or the like. Therefore, further integration can be realized as compared with the pill type package and flip chip mounting. Further, since further integration can be realized as compared with the pill type package and flip chip mounting, the transmission line length can be shortened.

  It is good also as a structure further provided with the high frequency utilization circuit part formed on the said board | substrate and connected to the said oscillation element and the said transistor.

  The oscillation element is preferably a Gunn diode composed of an n-type semiconductor layer formed of a direct transition type compound semiconductor having a zinc flash structure and a pair of electrodes.

  Since the Gunn diode has a relatively simple structure and a relatively large output can be obtained, the performance of the semiconductor device can be improved.

  The n-type semiconductor layer may be formed of one type of compound semiconductor selected from the group consisting of GaAs, InP, InSb, ZnSe, and CdTe, or a mixed crystal of at least two types of compound semiconductors.

  The n-type semiconductor layer is preferably made of GaInNAs.

  The transistor may be a heterostructure field effect transistor.

  The transistor may be a heterojunction bipolar transistor.

  The method for manufacturing a semiconductor device according to the present invention includes a step (a) of sequentially forming a first semiconductor layer and a second semiconductor layer on a substrate having a transistor region and an oscillation element region by epitaxial growth; (B) forming an oscillation element using the first semiconductor layer and the second semiconductor layer located on the oscillation element region after removing the second semiconductor layer located; and And (c) forming a transistor using the positioned first semiconductor layer.

  According to the present invention, the transistor and the oscillation element are mounted on the same substrate without using flip chip mounting or the like. Therefore, further integration can be realized as compared with the pill type package and flip chip mounting. Further, since further integration can be realized as compared with the pill type package and flip chip mounting, the transmission line length can be shortened. Furthermore, in the present invention, since the transistor and the oscillation element are formed simultaneously on the same substrate, it is easy to mount the transistor and the oscillation element with high accuracy. Therefore, according to the present invention, a semiconductor device in which variation in characteristics in the terahertz band is suppressed can be obtained.

  The second semiconductor layer is formed of one type of compound semiconductor selected from the group consisting of GaAs, InP, InSb, ZnSe, and CdTe, or an n-type semiconductor formed of a mixed crystal of at least two types of compound semiconductors. The oscillation element may be a Gunn diode.

  Another method of manufacturing a semiconductor device according to the present invention includes a step (a) of sequentially forming a first semiconductor layer and a second semiconductor layer on a substrate having a transistor region and an oscillation element region by epitaxial growth, and the oscillation described above. (B) forming a transistor using the first semiconductor layer and the second semiconductor layer located on the transistor region after removing the second semiconductor layer located in the device region; And (c) forming an oscillation element using the first semiconductor layer located in the region.

  According to the present invention, the transistor and the oscillation element are mounted on the same substrate without using flip chip mounting or the like. Therefore, further integration can be realized as compared with the pill type package and flip chip mounting. Further, since further integration can be realized as compared with the pill type package and flip chip mounting, the transmission line length can be shortened. Furthermore, in the present invention, since the transistor and the oscillation element are formed simultaneously on the same substrate, it is easy to mount the transistor and the oscillation element with high accuracy. Therefore, according to the present invention, a semiconductor device in which variation in characteristics in the terahertz band is suppressed can be obtained.

  The first semiconductor layer is formed of one type of compound semiconductor selected from the group consisting of GaAs, InP, InSb, ZnSe, and CdTe, or an n-type semiconductor formed of a mixed crystal of at least two types of compound semiconductors. The oscillation element may be a Gunn diode. .

  According to the present invention, it is possible to provide a semiconductor device in which variation in characteristics from a microwave band to a terahertz band is suppressed, mounting is easy, and a high-frequency signal can be efficiently transmitted to a space or an external circuit. Can do.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. For simplicity, components common to the embodiments are denoted by the same reference numerals. In the present specification, the term “high frequency” means a high frequency band of a microwave band or higher (about 1 GHz or higher).

(Embodiment 1)
FIG. 1 is a cross-sectional view showing the semiconductor device of this embodiment.

  As shown in FIG. 1, the semiconductor device 100 according to this embodiment includes a substrate 1 having a transistor region Rt and an oscillation element region Rg, a bipolar transistor 100 t formed on the transistor region Rt of the substrate 1, A Gunn diode 100g formed on the oscillation element region Rg.

  The bipolar transistor 100t is formed on the n-type semiconductor layer 2A formed on the transistor region Rt of the substrate 1, the n-type semiconductor layer 7 formed on the n-type semiconductor layer 2A, and the n-type semiconductor layer 7. p-type semiconductor layer 8, n-type semiconductor layer 9 A formed on p-type semiconductor layer 8, electrode 11 formed on n-type semiconductor layer 2 A, and electrode 12 formed on p-type semiconductor layer 8. And an electrode 13 formed on the n-type semiconductor layer 9A. In particular, in the present embodiment, the n-type semiconductor layer 2A is formed vertically so as to sandwich the n-semiconductor layer 3 and the n-semiconductor layer 3, and an n + semiconductor having a higher n-type impurity concentration than the n-semiconductor layer 3. It has a laminated structure including the layer 2 and the n + semiconductor layer 4. The n-type semiconductor layer 9 </ b> A has a stacked structure including an n− semiconductor layer 9 and an n + semiconductor layer 10 formed on the n− semiconductor layer 9 and having an n-type impurity concentration higher than that of the n− semiconductor layer 9. ing. In this embodiment, the electrode 11 functions as a collector electrode, the electrode 12 functions as a base electrode, and the electrode 13 functions as an emitter electrode. The electrodes 11, 12, and 13 include the n + semiconductor layer 4 and the p-type semiconductor layer. 8 and n + semiconductor layer 10 are in ohmic contact with each other.

  The Gunn diode 100g is formed on the oscillation element region Rg of the substrate 1 and is formed so as to sandwich the n− semiconductor layer 3 and the n− semiconductor layer 3, and has an n-type impurity concentration higher than that of the n− semiconductor layer 3. An n-type semiconductor layer 2A having a stacked structure composed of a high n + semiconductor layer 2 and an n + semiconductor layer 4, an electrode 5 formed on the n + semiconductor layer 2, and an electrode 6 formed on the n + semiconductor layer 4 It consists of and. The electrodes 5 and 6 are in ohmic contact with the n + semiconductor layers 2 and 4, respectively.

  Each of n-type semiconductor layer 2A (n + semiconductor layer 2, n− semiconductor layer 3 and n + semiconductor layer 4) included in both bipolar transistor 100t and Gunn diode 100g is laminated in exactly the same process in the manufacturing process described later. Since it is a thing, it represents with the common code | symbol.

  Although not shown, in the semiconductor device 100 of the present embodiment, an antenna, a Schottky diode, a capacitor, a transmission line, and the like are formed as a high-frequency utilization circuit in addition to the bipolar transistor and the Gunn diode, so that a desired function is achieved. Are appropriately combined so that can be obtained. For example, the Schottky diode is formed using any one of the above semiconductor layers.

  Here, the operation of the Gunn diode 100g will be described with reference to FIG. FIG. 2 is a cross-sectional view schematically showing the operation of the Gunn diode 100g.

  In the Gunn diode 100g, when the bias voltage applied to the electrode 6 is a positive voltage, the upper surface of the n− semiconductor layer 3 is substantially equipotential with the electrode 6, and the lower surface of the n− semiconductor layer 3 is approximately equipotential with the electrode 5. Thus, an electric field from the upper surface to the lower surface of the n − semiconductor layer 3 is generated in the n − semiconductor layer 3. Therefore, as shown in FIG. 2, a domain 13 that moves from the n + semiconductor layer 2 toward the n + semiconductor layer 4 is formed in the n− semiconductor layer 3. The oscillation frequency of the Gunn diode 100g is determined by the thickness L of the n− semiconductor layer 3 and is 0.5 μm here. However, this is one of the design matters, and it may be appropriately designed so as to obtain a desired oscillation frequency between 0.1 to 10 μm.

  Next, a method for manufacturing the semiconductor device 100 of this embodiment will be described with reference to the drawings. 3 and 4 are cross-sectional views showing a method for manufacturing the semiconductor device 100 of this embodiment.

  First, in the step shown in FIG. 3A, an n + semiconductor layer 2, an n− semiconductor layer 3, an n + semiconductor layer 4, an n− semiconductor layer 7, a p-type semiconductor layer 8, and an n− semiconductor layer 9 are formed on the substrate 1. Then, the n + semiconductor layer 10 is sequentially formed by epitaxial growth.

  Next, in the step shown in FIG. 3B, a resist (not shown) is formed on the n + semiconductor layer 10, and the substrate is formed into a transistor region Rt and an oscillation element region Rg by dry etching using this resist as a mask. Then, a recess 14 is formed to expose the surface of the substrate 1.

  Next, in the step shown in FIG. 3C, a resist (not shown) is formed on the n + semiconductor layer 10 and patterned. Next, the n− semiconductor layer 7, the p-type semiconductor layer 8, the n− semiconductor layer 9 and the n + semiconductor layer 10 are patterned by dry etching using this resist as a mask. Further, after removing the resist, another resist (not shown) is further formed on the n + semiconductor layer 10 and patterned. Subsequently, the n− semiconductor layer 9 and the n + semiconductor layer 10 are patterned by dry etching using the resist as a mask. At this time, the n− semiconductor layer 7, the p-type semiconductor layer 8, the n− semiconductor layer 9 and the n + semiconductor layer 10 in the oscillation element region Rg are removed.

  Next, in the step shown in FIG. 4A, a resist (not shown) is formed on the substrate and patterned. Next, by patterning the n + semiconductor layer 4 and the n− semiconductor layer 3 in the oscillation element region Rg by dry etching using this resist as a mask, the recess 15 exposing the surface of the n + semiconductor layer 2 is formed.

  Next, in the step shown in FIG. 4B, the electrode 5 is formed on the surface of the n + semiconductor layer 2 exposed in the recess 15 by a lift-off method. Similarly, the electrode 6 is also formed on the surface of the n + semiconductor layer 4 by a lift-off method. The electrodes 11, 12, and 13 are also formed on the surfaces of the n + semiconductor layer 4, the p-type semiconductor layer 8, and the n + semiconductor layer 10 by a lift-off method, respectively.

  Through the above steps, the semiconductor device 100 of this embodiment can be manufactured.

  The semiconductor device 100 of this embodiment has a structure in which the bipolar transistor 100t and the Gunn diode 100g are formed on the same substrate. That is, in the semiconductor device 100, the bipolar transistor 100t and the Gunn diode 100g are mounted on the same substrate without using flip chip mounting or the like. Therefore, further integration can be realized as compared with the pill type package and flip chip mounting applied to the conventional Gunn diode. Further, in the semiconductor device 100 of this embodiment, further integration can be realized as compared with the pill type package and flip chip mounting applied to the conventional Gunn diode, so that the transmission line length can be shortened.

  Furthermore, in order to use the Gunn diode in a terahertz band circuit, the tolerance of accuracy variation when mounting the Gunn diode is about the same as the wavelength of the target frequency (300 μm at 3 THz). In the embodiment, since the bipolar transistor and the Gunn diode are simultaneously formed on the same substrate, it is easy to mount the Gunn diode with the above accuracy. Therefore, variation in characteristics in the terahertz band of the semiconductor device 100 of this embodiment is suppressed.

  Furthermore, in this embodiment, a desired oscillation frequency can be obtained by appropriately designing the thickness L of the n − semiconductor layer 3. In a general semiconductor device manufacturing process, the thickness L of the n − semiconductor layer 3 can be easily reduced, for example, compared to the distance between wirings. Therefore, it is easy to operate the Gunn diode 100g at a higher frequency, and a semiconductor device that operates at a very high frequency can be provided.

  In the semiconductor device 100 of this embodiment, one Gunn diode 100g is provided, but the present invention is not limited to this. For example, in the semiconductor device 100 of this embodiment, a Gunn diode having a different thickness L of the n − semiconductor layer 3 can be formed at a different location on the substrate 1 from the Gunn diode 100g. By using the semiconductor device 100 of this embodiment configured as described above for a communication device used in a communication method using a plurality of different frequencies or a communication device for switching a plurality of frequency bands, the communication device can be reduced in size. .

  In the present embodiment, a hetero bipolar transistor (HBT) may be used as the bipolar transistor 100t. In particular, when HBT is used, two layers of an n-type semiconductor layer and an n + semiconductor layer containing a high-concentration n-type impurity may be added between the collector and the collector electrode in order to improve high-frequency characteristics. A plurality of n-type semiconductor layers may be stacked as a layer.

(Embodiment 2)
In the present embodiment, a semiconductor device having a structure different from that of the first embodiment will be described with reference to the drawings. For the sake of simplicity, the same components as those in the first embodiment are denoted by the same reference numerals.

  FIG. 5 is a cross-sectional view showing the semiconductor device of this embodiment.

  As shown in FIG. 5, the semiconductor device 200 according to the present embodiment includes a substrate 1 having a transistor region Rt and an oscillation element region Rg, a bipolar transistor 200 t formed on the transistor region Rt of the substrate 1, A Gunn diode 200g formed on the oscillation element region Rg.

  The bipolar transistor 200t is formed on the n-type semiconductor layer 22 formed on the transistor region Rt of the substrate 1, the n-type semiconductor layer 23 formed on the n-type semiconductor layer 22, and the n-type semiconductor layer 23. The p-type semiconductor layer 24, the n-type semiconductor layer 27 A formed on the p-type semiconductor layer 24, the electrode 31 formed on the n-type semiconductor layer 22, and the electrode 32 formed on the p-type semiconductor layer 24 And an electrode 33 formed on the n-type semiconductor layer 27A. In particular, in the present embodiment, the n-type semiconductor layer 27A includes an n− semiconductor layer 27 and an n + semiconductor layer 28 formed on the n− semiconductor layer 27 and having a higher n-type impurity concentration than the n− semiconductor layer 27. It becomes the laminated structure which becomes. In the present embodiment, the electrode 31 functions as a collector electrode, the electrode 32 functions as a base electrode, and the electrode 33 functions as an emitter electrode. The electrodes 31, 32, and 33 include the n-type semiconductor layer 22 and the p-type semiconductor. The layer 24 and the n + semiconductor layer 28 are in ohmic contact with each other.

  The Gunn diode 200g is formed on the n-type semiconductor layer 22 formed on the oscillation element region Rg of the substrate 1, the n-type semiconductor layer 23 formed on the n-type semiconductor layer 22, and the n-type semiconductor layer 23. P-type semiconductor layer 24, n-type semiconductor layer 27A formed on p-type semiconductor layer 24, n-type semiconductor layer 29A formed on n-type semiconductor layer 27A, and n-type semiconductor layer 27A (n + semiconductor) The electrode 25 is formed on the layer 28) and the electrode 26 is formed on the n-type semiconductor layer 29A. In particular, in the present embodiment, the n-type semiconductor layer 29A includes an n− semiconductor layer 29 and an n + semiconductor layer 30 formed on the n− semiconductor layer 29 and having a higher n-type impurity concentration than the n− semiconductor layer 29. It becomes the laminated structure which becomes. The electrodes 25 and 26 are in ohmic contact with the n + semiconductor layers 28 and 30, respectively.

  The n-type semiconductor layer 22, the n-type semiconductor layer 23, the p-type semiconductor layer 24, and the n-type semiconductor layer 27A (the n− semiconductor layer 27 and the n + semiconductor layer 28) included in both the bipolar transistor 200t and the Gunn diode 200g. Since these are stacked in exactly the same step in the manufacturing process described later, they are denoted by common reference numerals.

  Although not shown, in the semiconductor device 200 of the present embodiment, an antenna, a Schottky diode, a capacitor, a transmission line (for example, a filter), and the like are formed as a high-frequency utilization circuit in addition to the bipolar transistor and the Gunn diode. Are combined as appropriate so as to obtain a desired function. For example, the Schottky diode is formed using any one of the above semiconductor layers.

  The operation of the Gunn diode 200g is the same as the operation of the Gunn diode 100g described in the first embodiment, and the description thereof is omitted here.

  Next, a method for manufacturing the semiconductor device 200 of this embodiment will be described with reference to the drawings. 6 and 7 are cross-sectional views showing a method for manufacturing the semiconductor device 200 of this embodiment.

  First, in the process shown in FIG. 6A, an n-type semiconductor layer 22, an n-type semiconductor layer 23, a p-type semiconductor layer 24, an n− semiconductor layer 27, an n + semiconductor layer 28, and an n− semiconductor layer are formed on the substrate 1. 29 and the n + semiconductor layer 30 are sequentially formed by epitaxial growth.

  Next, in the step shown in FIG. 6B, a resist (not shown) is formed on the n + semiconductor layer 30, and the substrate is formed into a transistor region Rt and an oscillation element region Rg by dry etching using this resist as a mask. Then, a recess 14 is formed to expose the surface of the substrate 1.

  Next, in the step shown in FIG. 6C, a resist (not shown) is formed on the n + semiconductor layer 30 and patterned. Next, the n− semiconductor layer 29 and the n + semiconductor layer 30 are patterned by dry etching using the resist as a mask. As a result, a recess 35 exposing the surface of the n + semiconductor layer 28 is formed in the oscillation element region Rg. At this time, the n− semiconductor layer 27, the n + semiconductor layer 28, the n− semiconductor layer 29, and the n + semiconductor layer 30 in the transistor region Rt are removed.

  Next, in the step shown in FIG. 7A, a resist (not shown) is formed on the substrate and patterned. Next, the n-type semiconductor layer 23, the p-type semiconductor layer 24, the n− semiconductor layer 27, and the n + semiconductor layer 28 in the transistor region Rt are patterned by dry etching using the resist as a mask. Further, after removing the resist, another resist (not shown) is further formed on the substrate and patterned. Subsequently, the n− semiconductor layer 27 and the n + semiconductor layer 28 are patterned by dry etching using the resist as a mask.

  Next, in the step shown in FIG. 7B, the electrode 25 is formed on the surface of the n + semiconductor layer 28 exposed in the recess 15 by a lift-off method. Similarly, the electrode 26 is also formed on the surface of the n + semiconductor layer 30 by a lift-off method. The electrodes 31, 32 and 33 are also formed on the surfaces of the n-type semiconductor layer 22, the p-type semiconductor layer 24 and the n + semiconductor layer 28 by a lift-off method, respectively.

  Through the above steps, the semiconductor device 200 of this embodiment can be manufactured.

  Similar to the semiconductor device 100 of the first embodiment, the semiconductor device 200 of the present embodiment has a structure in which a bipolar transistor 200t and a Gunn diode 200g are formed on the same substrate. The semiconductor device 100 is different from the semiconductor device 100 only in the structure of the semiconductor layer formed on the substrate 1. Therefore, according to the present embodiment, the same effects as those of the first embodiment can be obtained.

  In the present embodiment, a hetero bipolar transistor (HBT) may be used as the bipolar transistor 200t. In particular, when HBT is used, two layers of an n-type semiconductor layer and an n + semiconductor layer containing a high-concentration n-type impurity may be added between the collector and the collector electrode in order to improve high-frequency characteristics. A plurality of n-type semiconductor layers may be stacked as a layer.

(Embodiment 3)
In the present embodiment, a semiconductor device having a structure different from those of the first and second embodiments will be described with reference to the drawings. For the sake of simplicity, the same components as those in the first and second embodiments are denoted by the same reference numerals.

  FIG. 8 is a cross-sectional view showing the semiconductor device of this embodiment.

  As shown in FIG. 8, the semiconductor device 300 of this embodiment includes a substrate 1 having a transistor region Rt and an oscillation element region Rg, and a high electron mobility transistor (hereinafter, referred to as a transistor region Rt of the substrate 1). 300t) and a Gunn diode 300g formed on the oscillation element region Rg of the substrate 1.

  The HEMT 300t is formed on the non-doped semiconductor layer 41 formed on the transistor region Rt of the substrate 1, the n-type semiconductor layer 42 formed on the non-doped semiconductor layer 41, and the n-type semiconductor layer 42. The n + semiconductor layer 43 has an n-type impurity concentration higher than that of the electrode 42, the electrode 48 formed on the n-type semiconductor layer 42, and the electrode 49 formed on the n + semiconductor layer 43. The electrode 48 is in Schottky contact with the n-type semiconductor layer 42 and functions as a gate electrode. The electrode 49 is in ohmic contact with the n + semiconductor layer 43 and functions as a source / drain electrode.

  The Gunn diode 300g includes a non-doped semiconductor layer 41 formed on the oscillation element region Rg of the substrate 1, an n-type semiconductor layer 42 formed on the non-doped semiconductor layer 41, and an n + formed on the n-type semiconductor layer 42. The semiconductor layer 43 is formed on the n + semiconductor layer 43 and has a lower n-type impurity concentration than the n + semiconductor layer 43. The n− semiconductor layer 44 is formed on the n− semiconductor layer 44 and is higher than the n− semiconductor layer 44. The n + semiconductor layer 45 having a high n-type impurity concentration, an electrode 46 formed on the n + semiconductor layer 43, and an electrode 47 formed on the n + semiconductor layer 45 are configured. The electrodes 46 and 47 are in ohmic contact with the n + semiconductor layers 43 and 45, respectively.

  Since each of the non-doped semiconductor layer 41, the n-type semiconductor layer 42, and the n + semiconductor layer 43 included in both the HEMT 300t and the Gunn diode 300g is laminated in exactly the same process in the manufacturing process described later, the common reference numerals are used. Represents.

  Although not shown, in the semiconductor device 300 of this embodiment, an antenna, a Schottky diode, a capacitor, a transmission line (for example, a filter), and the like are formed as a high-frequency utilization circuit in addition to the bipolar transistor and the Gunn diode. Are combined as appropriate so as to obtain a desired function. For example, the Schottky diode is formed using any one of the above semiconductor layers.

  The operation of the Gunn diode 300g is the same as the operation of the Gunn diode 100g described in the first embodiment, and the description thereof is omitted here.

  In the HEMT 300t, a two-dimensional electron gas as shown by a broken line in FIG. 8 is generated in the non-doped semiconductor layer 41 by the lamination of the non-doped semiconductor layer 41 serving as a channel layer and the n-type semiconductor layer 42 serving as an electron supply layer. For this reason, when the voltage applied to the electrode 48 as a gate is changed, the concentration of the two-dimensional electron gas increases or decreases. As a result, since the drain current flowing between the source and the drain changes, transistor characteristics can be obtained. Since the two-dimensional electron channel in which the two-dimensional electron gas is accumulated is formed in the non-doped semiconductor layer 41, it is not scattered by impurities when the electrons travel. For this reason, it is possible to operate at higher speed and higher frequency than GaAsFET or the like, and to obtain characteristics of low noise.

  Next, a method for manufacturing the semiconductor device 300 of this embodiment will be described with reference to the drawings. 9 and 10 are cross-sectional views showing a method for manufacturing the semiconductor device 300 of this embodiment.

  First, in the step shown in FIG. 9A, a non-doped semiconductor layer 41, an n-type semiconductor layer 42, an n + semiconductor layer 43, an n− semiconductor layer 44, and an n + semiconductor layer 45 are sequentially formed on the substrate 1 by epitaxial growth.

  Next, in the step shown in FIG. 9B, a resist (not shown) is formed on the n + semiconductor layer 45, and the substrate is formed into a transistor region Rt and an oscillation element region Rg by dry etching using this resist as a mask. A recess 54 that exposes the surface of the substrate 1 is formed.

  Next, in the step shown in FIG. 9C, a resist (not shown) is formed on the n + semiconductor layer 45 and patterned. Next, the n− semiconductor layer 44 and the n + semiconductor layer 45 are patterned by dry etching using the resist as a mask. As a result, a recess 55 exposing the surface of the n + semiconductor layer 43 is formed in the oscillation element region Rg. At this time, the n− semiconductor layer 44 and the n + semiconductor layer 45 in the transistor region Rt are removed.

  Next, in the step shown in FIG. 10A, a resist (not shown) is formed on the substrate and patterned. Next, an opening 56 exposing the surface of the n-type semiconductor layer 42 is formed in the n + semiconductor layer 43 of the transistor region Rt by dry etching using this resist as a mask.

  Next, in the step shown in FIG. 10B, the electrode 46 is formed on the surface of the n + semiconductor layer 43 exposed in the recess 55 by a lift-off method. Similarly, the electrode 47 is also formed on the surface of the n + semiconductor layer 45 by a lift-off method. The electrodes 48 and 49 are also formed on the surfaces of the n-type semiconductor layer 42 and the n + semiconductor layer 43 by a lift-off method, respectively.

  Through the above steps, the semiconductor device 300 of this embodiment can be manufactured.

  The semiconductor device 300 of this embodiment has a structure in which the HEMT 300t and the Gunn diode 100g are formed on the same substrate. That is, in the semiconductor device 300, the HEMT 300t and the Gunn diode 100g are mounted on the same substrate without using flip chip mounting or the like. Therefore, further integration can be realized as compared with the pill type package and flip chip mounting applied to the conventional Gunn diode. Further, in the semiconductor device 300 of this embodiment, further integration can be realized as compared with the pill type package and flip chip mounting applied to the conventional Gunn diode, so that the transmission line length can be shortened.

  Furthermore, in order to use the Gunn diode in a terahertz band circuit, the tolerance of accuracy variation when mounting the Gunn diode is about the same as the wavelength of the target frequency (300 μm at 3 THz). In the embodiment, since the HEMT and the Gunn diode are simultaneously formed on the same substrate, it is easy to mount the Gunn diode with the above accuracy. Therefore, variation in characteristics in the terahertz band of the semiconductor device 300 of this embodiment is suppressed.

  Furthermore, in this embodiment, a desired oscillation frequency can be obtained by appropriately designing the thickness of the n − semiconductor layer 44. In a general semiconductor device manufacturing process, the thickness of the n − semiconductor layer 44 can be easily reduced, for example, compared to the distance between wirings. Therefore, it is easy to operate the Gunn diode 300g at a higher frequency, and a semiconductor device that operates at a very high frequency can be provided.

  In the semiconductor device 300 of this embodiment, one Gunn diode 300g is provided, but the present invention is not limited to this. For example, in the semiconductor device 300 of this embodiment, a Gunn diode having a different thickness of the n − semiconductor layer 44 can be formed at a location different from the Gunn diode 300 g on the substrate 1. By using the semiconductor device 300 of the present embodiment configured as described above for a communication device used in a communication method using a plurality of different frequencies or a communication device for switching a plurality of frequency bands, the communication device can be downsized. .

  In general, a HEMT often uses a single non-doped semiconductor layer as a channel layer in which a two-dimensional electron channel is formed, as in the semiconductor device 300 of the present embodiment. However, the present invention is not limited to this, and instead of the non-doped semiconductor layer 41, the channel layer is a stacked structure in which a semiconductor layer having a small band gap is sandwiched between semiconductor layers having a large band gap and electrons are confined in the semiconductor layer having a small band gap. Also good.

  Further, instead of the n-type semiconductor layer 42 as the electron supply layer, a semiconductor layer having a δ-doped structure in which impurities are locally introduced may be used.

  Furthermore, instead of the HEMT 300t, a HEMT having a double hetero structure in which electron supply layers are arranged above and below the channel layer may be used.

(Embodiment 4)
In the present embodiment, a semiconductor device having a structure different from those of the first to third embodiments will be described with reference to the drawings. For the sake of simplicity, the same components as those in the first to third embodiments are denoted by the same reference numerals.

  FIG. 11 is a cross-sectional view showing the semiconductor device of this embodiment.

  As shown in FIG. 11, the semiconductor device 400 of this embodiment includes a substrate 1 having a transistor region Rt and an oscillation element region Rg, and a high electron mobility transistor (hereinafter referred to as a transistor region Rt) formed on the substrate 1. 400t) and a Gunn diode 400g formed on the oscillation element region Rg of the substrate 1.

  The HEMT 400t includes an n-type semiconductor layer 62A formed on the transistor region Rt of the substrate 1, a non-doped semiconductor layer 67 formed on the n-type semiconductor layer 62A, and an n-type semiconductor layer formed on the non-doped semiconductor layer 67. 68, an n + semiconductor layer 69 formed on the n-type semiconductor layer 68 and having an n-type impurity concentration higher than that of the n-type semiconductor layer 68, an electrode 71 formed on the n-type semiconductor layer 68, and the n + semiconductor layer 69. And an electrode 72 formed thereon. In particular, in the present embodiment, the n-type semiconductor layer 62A is formed vertically so as to sandwich the n-semiconductor layer 63 and the n-semiconductor layer 63, and an n + semiconductor having a higher n-type impurity concentration than the n-semiconductor layer 63. A laminated structure including the layer 62 and the n + semiconductor layer 64 is formed. The electrode 71 is in Schottky contact with the n-type semiconductor layer 68 and functions as a gate electrode. The electrode 72 is in ohmic contact with the n + semiconductor layer 69 and functions as a source / drain electrode.

  The Gunn diode 400g is formed on the oscillating element region Rg of the substrate 1 and is formed so as to sandwich the n− semiconductor layer 63 and the n− semiconductor layer 63, and has an n-type impurity concentration higher than that of the n− semiconductor layer 63. An n-type semiconductor layer 62A having a stacked structure including a high n + semiconductor layer 62 and an n + semiconductor layer 64, an electrode 65 formed on the n + semiconductor layer 62, and an electrode 66 formed on the n + semiconductor layer 64 It consists of and. The electrodes 65 and 66 are in ohmic contact with the n + semiconductor layers 62 and 64, respectively.

  Each of the n-type semiconductor layer 62A (n + semiconductor layer 62, n− semiconductor layer 63, and n + semiconductor layer 64) included in both the bipolar transistor 400t and the Gunn diode 400g is laminated in exactly the same process in the manufacturing process described later. Since it is a thing, it represents with the common code | symbol.

  Although not shown, in the semiconductor device 400 of this embodiment, an antenna, a Schottky diode, a capacitor, a transmission line (for example, a filter) and the like are formed as a high-frequency utilization circuit in addition to the bipolar transistor and the Gunn diode. Are combined as appropriate so as to obtain a desired function. For example, the Schottky diode is formed using any one of the above semiconductor layers.

  The operation of the Gunn diode 400g is the same as the operation of the Gunn diode 100g described in the first embodiment, and the operation of the HEMT 400t is the same as the operation of the HEMT 400t described in the third embodiment. To do.

  Next, a method for manufacturing the semiconductor device 400 of this embodiment will be described with reference to the drawings. 12 and 13 are cross-sectional views showing a method for manufacturing the semiconductor device 400 of this embodiment.

  First, in the process shown in FIG. 12A, an n + semiconductor layer 62, an n− semiconductor layer 63, an n + semiconductor layer 64, a non-doped semiconductor layer 67, an n-type semiconductor layer 68, and an n + semiconductor layer 69 are sequentially formed on the substrate 1. It is formed by epitaxial growth.

  Next, in the step shown in FIG. 12B, a resist (not shown) is formed on the n + semiconductor layer 69, and the substrate is formed into a transistor region Rt and an oscillation element region Rg by dry etching using this resist as a mask. A recess 54 that exposes the surface of the substrate 1 is formed.

  Next, in the step shown in FIG. 12C, a resist (not shown) is formed on the n + semiconductor layer 69 and patterned. Next, an opening 75 exposing the surface of the n-type semiconductor layer 68 is formed in the n + semiconductor layer 69 of the transistor region Rt by dry etching using this resist as a mask.

  Next, in the step shown in FIG. 13A, a resist (not shown) is formed on the substrate and patterned. Next, by patterning the n + semiconductor layer 64 and the n− semiconductor layer 63 in the oscillation element region Rg by dry etching using this resist as a mask, a recess 76 exposing the surface of the n + semiconductor layer 2 is formed.

  Next, in the step shown in FIG. 13B, the electrode 65 is formed on the surface of the n + semiconductor layer 62 exposed in the recess 76 by a lift-off method. Similarly, the electrode 66 is also formed on the surface of the n + semiconductor layer 64 by a lift-off method. The electrodes 71 and 72 are also formed on the surfaces of the n-type semiconductor layer 68 and the n + semiconductor layer 69 by a lift-off method, respectively.

  Through the above steps, the semiconductor device 400 of this embodiment can be manufactured.

  Similar to the semiconductor device 300 of the third embodiment, the semiconductor device 400 of the present embodiment has a structure in which the HEMT 400t and the Gunn diode 400g are formed on the same substrate, and the semiconductor device of the third embodiment. The only difference from 300 is the structure of the semiconductor layer formed on the substrate 1. Therefore, according to the present embodiment, the same effects as those of the third embodiment can be obtained.

  Also in this embodiment, the channel layer in which the two-dimensional electron channel of the HEMT 400t is formed is replaced with the non-doped semiconductor layer 67, and a semiconductor layer with a small band gap is sandwiched between semiconductor layers with a large band gap, and electrons are A stacked structure confined in a small semiconductor layer may be employed.

  Further, instead of the n-type semiconductor layer 68 as the electron supply layer, a semiconductor layer having a δ-doped structure in which impurities are locally introduced may be used.

  Further, instead of the HEMT 400t, a HEMT having a double hetero structure in which electron supply layers are arranged above and below the channel layer may be used.

(Other embodiments)
The Gunn diodes 100g to 400g shown in the first to fourth embodiments all have the same structure, but the present invention is not limited to these. For example, various structures such as an n-type semiconductor layer having a gradient in impurity concentration and an n + semiconductor layer having a different impurity concentration are put into practical use as an n-type semiconductor that produces a gun effect, such as an n-type semiconductor layer having a gradient in impurity concentration in order to improve oscillation characteristics. Yes. In each of the above embodiments, Gunn diodes having these structures may be used instead of the Gunn diodes 100g to 400g.

  In the Gunn diode, the impurity concentration at which the dipole mode and the hybrid mode are generated is empirically required to be a shaded area shown in FIG. Therefore, based on FIG. 20, depending on the characteristics required for the Gunn diode for each application, each of the n-semiconductor layers 2, 4, 28, 30, 43, 45, 62 of the Gunn diodes 100g to 400g mentioned above and The impurity concentration of 64n and each of the n + semiconductor layers 3, 29, 44, and 63 may be appropriately selected.

  Furthermore, in the semiconductor device of each embodiment, each n− semiconductor layer 2, 4, 28, 30, 43, 45, 62 and 64n of the Gunn diodes 100g to 400g and each n + semiconductor layer 3, 29, 44 and 63 are The direct transition type compound semiconductor having a zinc flash structure may be formed of any material as long as it exhibits a cancer effect. Specifically, the direct transition type compound semiconductor having a zinc flash structure is GaAs, InP, InSb, ZnSe, CdTe, or a mixed crystal thereof. The n-type impurities introduced into the n-semiconductor layers 2, 4, 28, 30, 43, 45, 62 and 64n and the n + semiconductor layers 3, 29, 44 and 63 are the same as those of the semiconductor layers described above. Si, S, Se, etc. may be used when formed from InP, and S, etc. may be used when formed from GaAs.

  Also, each n− semiconductor layer 2, 4, 28, 30, 43, 45, 62 and 64n, and each n + semiconductor layer 3, 29, 44 and 63 may be formed of a material containing N in a GaInAs semiconductor. Good. This is because by introducing N into the GaInAs-based semiconductor, the saturation speed of electrons in GaInAs is reduced and the oscillation frequency of the oscillation element is slightly reduced, but the operation of the oscillation element is increased in stability.

  Furthermore, in each of the above embodiments, the substrate 1 is made of Fe-doped semi-insulating InP or non-doped semi-insulating GaAs, but is not limited thereto. For example, the substrate 1 may be a semiconductor substrate such as a non-doped semi-insulating GaAs substrate, a substrate formed of ceramics, benzocyclobutene (BCB), polyimide resin, liquid crystal polymer, or the like. In particular, when a substrate formed of ceramics, benzocyclobutene (BCB), polyimide resin, liquid crystal polymer, or the like is used as a mother substrate, it is easier to obtain materials than when a semiconductor substrate is used as a mother substrate. Cost can be reduced.

  In the semiconductor devices 100 to 400 described in the present embodiment, the Gunn diodes 100g to 400g are used. However, the semiconductor devices 100 to 400g are not limited to Gunn diodes, and other two-terminal elements exhibiting negative resistance characteristics can be used. is there. Examples of other two-terminal elements exhibiting negative resistance characteristics include IMPATT diodes using an avalanche phenomenon of electrons and tunnel diodes using negative resistance characteristics.

  Examples of the present invention will be described below. In addition, the Example shown below does not limit this invention.

(Example 1)
The present embodiment will be described with reference to FIGS. 11 and 14. FIG. 14 is a plan view schematically illustrating a specific configuration example of the semiconductor device 400 of the fourth embodiment.

  In the semiconductor device 400 of the present embodiment shown in FIG. 14, the output from the Gunn diode 400g is passed through a 1/2 wavelength transmission line type filter and input to a frequency multiplier made of a Schottky diode. The second harmonic of the oscillation frequency generated by the vessel is radiated into the space from the bowtie antenna.

  In this embodiment, a Fe-doped semi-insulating InP substrate is used as the substrate 1 of the semiconductor device 400, and the filter, frequency multiplier, bow tie antenna, low-pass filter, bias pad, and radial stub are all on the substrate 1. Is formed. Further, a metal thin film serving as a ground plane is formed on the lower surface of the substrate 1 and used. In this embodiment, the HEMT constituting the frequency multiplier corresponds to the HEMT 400t of the semiconductor device 400.

In particular, in the Gunn diode 400g of this example, as the n + semiconductor layer 62, a Si-doped InGaAs layer (impurity concentration of 1 × 10 ¹⁹ cm ⁻³ ) lattice-matched to the InP substrate, and as the n− semiconductor layer 63, a Si-doped InGaAs layer (impurity) concentration 1X10 ¹⁵ ~1X10 ¹⁹ cm ^-3), is used further InGaAs layer doped with Si as an n + semiconductor layer 64 (the impurity concentration 1X10 ¹⁹ cm ^-3). The InGaAs impurity concentration and the film thickness of the n − semiconductor layer 63 causing the gun effect were changed according to the used oscillation frequency.

The Schottky diode constituting the frequency multiplier is formed by the same process as the process shown in FIG. 13B of the fourth embodiment. The n + semiconductor layer 64 of the HEMT 400t is common to the Gunn diode, and a laminated film made of non-doped InAlAs and InGaAs is formed thereon as a non-doped semiconductor layer 67 that becomes a channel layer. Further, a stacked film made of i-InAlAs, n-InAlAs, and i-InAlAs was formed as the n-type semiconductor layer 68 serving as an electron supply layer. In particular, Si was used as an n-type impurity of n-InAlAs that supplies electrons as carriers in the laminated film (impurity concentration: 1 × 10 ¹⁸ cm ⁻³ ). Further, an InP layer is formed as an etch stop layer (not shown) for manufacturing, and an Si-doped n-InGaAs layer (impurity concentration: 1 × 10 ¹⁹ cm ⁻³ ) is formed as an ohmic contact on the uppermost layer.

  The filter, frequency multiplier, bowtie antenna, low-pass filter, bias pad, and radial stub were formed using an Au thin film. The ohmic contact between the electrodes 65, 66, 71, and 72 and the n + semiconductor layers 62, 64, and 69 in the semiconductor device 400 forms the electrodes 65, 66, 71, and 72 using an AuGeNi layer, and is in a nitrogen atmosphere. The junction resistance was reduced by heat treatment at about 300 ° C.

  As an operation of the semiconductor device 400, a high frequency oscillation characteristic was exhibited in an electric field in which a voltage applied to the Gunn diode 400g was larger than a certain threshold electric field Eth. Further, the frequency slightly changed depending on the DC voltage value, and the oscillation frequency could be adjusted. It was also confirmed that the double wave of this high frequency oscillation was radiated from the dipole antenna.

  In this embodiment, a Gunn diode capable of oscillating at a high frequency, a frequency multiplier, a filter, an antenna, and the like are integrated on one substrate, which is effective for downsizing the oscillation circuit.

  Further, the semiconductor device 400 could be manufactured with good reproducibility when a plurality of identical circuits were produced. In particular, the operating frequency of the Gunn diode can be designed with the film thickness of the n − semiconductor layer 63. For this reason, by setting the oscillation frequency to several hundred GHz, the high frequency irradiated to the outside can be increased to the terahertz region.

  In this embodiment, since a plurality of semiconductor layers are epitaxially grown on a semi-insulating InP substrate, the crystallinity of each layer is equivalent to that of a single crystal material, which is effective in improving the characteristics as an oscillation circuit. The operation frequency of the Gunn diode 400g was higher than that using a GaAs substrate.

(Example 2)
This embodiment will be described with reference to FIGS. FIG. 15 is a plan view schematically illustrating a specific configuration example of the semiconductor device 300 according to the third embodiment.

  The semiconductor device 300 of this embodiment shown in FIG. 15 receives a high-frequency signal, and uses an output from the Gunn diode 300g as a local signal. In the semiconductor device 300, the local signal passes through a 1/2 wavelength transmission line type filter and is input to the Schottky diode mixer. On the other hand, the high frequency signal is applied from the space to the Schottky diode mixer through the bow tie antenna. Here, the IF signal of the intermediate frequency (IF) mixed and down-converted with the local signal passes through the low-pass filter, is amplified by the IF amplifier, and is taken out from the IF signal output terminal.

  In this embodiment, a Fe-doped semi-insulating InP substrate is used as the substrate 1 of the semiconductor device 300, and the filter, Schottky diode mixer, bowtie antenna, low-pass filter, bias pad, and radial stub are all on the substrate 1. Is formed. Further, a metal thin film serving as a ground plane is formed on the lower surface of the substrate 1 and used. In this embodiment, each HEMT constituting the IF amplifier and the Schottky diode mixer corresponds to the HEMT 300 t of the semiconductor device 300.

  The IF amplifier and the Schottky diode mixer are formed using a common semiconductor layer (non-doped semiconductor layer 41, n-type semiconductor layer 42, and n + semiconductor layer 43) constituting the HEMT 300t.

  The filter, the bow tie antenna, the low-pass filter, the bias pad, and the radial stub are all formed on the substrate 1. Further, a metal thin film serving as a ground plane is formed on the lower surface of the substrate 1 and used.

In particular, the IF amplifier and the Schottky diode mixer, which are the HEMT 300t of the present embodiment, include a non-doped i-InAlAs serving as a buffer layer and a non-doped i serving as a channel layer formed thereon as the non-doped semiconductor layer 41 on the InP substrate. A laminated film composed of -InGaAs and a non-doped i-InAlAs layer as a spacer layer formed thereon is further provided. As the n-type semiconductor layer 42 serving as the electron supply layer, a Si-doped n-InAlAs layer (impurity concentration 5 × 10 ¹⁸ cm ⁻³ ) and a non-doped i-InAlAs layer were further formed thereon. On the n-type semiconductor layer 42, a non-doped i-InP layer is formed as a manufacturing etch stop layer, and an Si-doped n-InGaAs layer (impurity concentration) serving as an n + semiconductor layer 43 serving as a cap layer is formed thereon. 1 × 10 ¹⁹ cm ⁻³ ) was formed.

In the Gunn diode 300g of the present embodiment, the n + semiconductor layer 43 is the same Si-doped n-InGaAs layer (impurity concentration 1 × 10 ¹⁹ cm ⁻³ ) as the cap layer of the HEMT 300t, and the n− semiconductor layer 44 is an n-InGaAs layer (impurity). the concentration 1X10 ¹⁵ ~1X10 ¹⁹ cm ^-3), was used n ⁺ -InGaAs layer as n + semiconductor layer 45 (the impurity concentration 1X10 ¹⁹ cm ^-3). The impurity concentration and film thickness of the n-InGaAs layer of the n-semiconductor layer 44 that causes the gun effect were changed according to the oscillation frequency used.

  The filter, bow tie antenna, low pass filter, bias pad, and radial stub were formed using an Au thin film. The ohmic contact between the electrodes 46, 47, and 49 and the n + semiconductor layers 43 and 47 in the semiconductor device 300 is performed by forming the electrodes 46, 47, and 49 using an AuGeNi layer and performing a heat treatment at about 300 ° C. in a nitrogen atmosphere. Reduced junction resistance.

  As an operation of the semiconductor device 300, high-frequency oscillation characteristics were exhibited in an electric field in which the voltage applied to the Gunn diode 300g was larger than a certain threshold electric field Eth. Further, the frequency slightly changed depending on the DC voltage value, and the oscillation frequency could be adjusted. Further, the IF signal obtained by mixing this high frequency oscillation as a local signal with a millimeter wave signal input from the outside through an antenna can be amplified by an IF amplifier and taken out from the IF signal output terminal.

  In this embodiment, a Gunn diode capable of oscillating at a high frequency, a filter, a Schottky diode mixer, a bow tie antenna, and the like are integrated on one substrate, which is effective for downsizing the receiving circuit.

  In addition, the semiconductor device 300 can be manufactured with good reproducibility when a plurality of identical circuits are formed. In particular, the operating frequency of the Gunn diode 300g can be designed with the film thickness of the n − semiconductor layer 44. For this reason, by setting the oscillation frequency to several hundreds of GHz, it was possible to down-convert the super-high frequency over the terahertz region as the received signal.

  In this embodiment, since a plurality of semiconductor layers are epitaxially grown on a semi-insulating InP substrate, the crystallinity of each layer is equivalent to that of a single crystal material, which is effective in improving the characteristics as an oscillation circuit. The oscillation frequency of the Gunn diode 300g was able to operate at a higher frequency than that using a GaAs substrate.

(Example 3)
This embodiment will be described with reference to FIGS. FIG. 16 is a plan view schematically showing another specific configuration example of the semiconductor device 300 of the third embodiment.

  A semiconductor device 300 of this embodiment shown in FIG. 16 receives a high frequency signal in the millimeter wave band, and uses an output from the Gunn diode 300g as a local signal. In the semiconductor device 300, the local signal passes through a 1/2 wavelength transmission line type filter and is input to the FET mixer. On the other hand, the millimeter wave signal is received from the space by the patch antenna and amplified by the low noise amplifier. Next, after removing unnecessary signals through the filter, the IF signal is frequency-mixed with the local signal by the FET mixer, and the down-converted IF signal passes through the IF filter and is output from the IF signal output terminal.

  In this embodiment, a Fe-doped semi-insulating InP substrate is used as the substrate 1 of the semiconductor device 300, and the filter, FET mixer, patch antenna, IF filter, bias pad, and radial stub are all formed on the substrate 1. Has been. Further, a metal thin film serving as a ground plane is formed on the lower surface of the substrate 1 and used. In this embodiment, each HEMT constituting the FET mixer and the low noise amplifier corresponds to the HEMT 300 t of the semiconductor device 300.

  The FET mixer and the low noise amplifier were formed according to the third embodiment using the common semiconductor layers (non-doped semiconductor layer 41, n-type semiconductor layer 42, and n + semiconductor layer 43) constituting the HEMT 300t.

  The configuration of each semiconductor layer of the semiconductor device 300 of this embodiment is exactly the same as that of the second embodiment.

  The filter, patch antenna, IF filter, bias pad, and radial stub were formed using an Au thin film. The ohmic contact between the electrodes 46, 47, and 49 and the n + semiconductor layers 43 and 47 in the semiconductor device 300 is performed by forming the electrodes 46, 47, and 49 using an AuGeNi layer and performing a heat treatment at about 300 ° C. in a nitrogen atmosphere. Reduced junction resistance.

  As an operation of the semiconductor device 300, high-frequency oscillation characteristics were exhibited in an electric field in which the voltage applied to the Gunn diode 300g was larger than a certain threshold electric field Eth. Further, the frequency slightly changed depending on the DC voltage value, and the oscillation frequency could be adjusted. Further, the IF signal obtained by mixing this high frequency oscillation as a local signal with a millimeter wave signal input from the outside through an antenna can be amplified by an IF amplifier and taken out from the IF signal output terminal.

  In this embodiment, a Gunn diode that can oscillate at high frequency, a low-noise amplifier, an IF amplifier, an FET mixer, a filter, and an antenna are integrated on a single substrate, which is effective for downsizing the receiving circuit. Met.

  In addition, the semiconductor device 300 can be manufactured with good reproducibility when a plurality of identical circuits are formed. In particular, the operating frequency of the Gunn diode 300g can be designed with the film thickness of the n − semiconductor layer 44. For example, by setting the oscillation frequency to 55 to 80 GHz, it was possible to down-convert high frequency over a millimeter wave region of 60 GHz band or 77 GHz band as a received signal.

  In this embodiment, since a plurality of semiconductor layers are epitaxially grown on a semi-insulating InP substrate, the crystallinity of each layer is equivalent to that of a single crystal material, which is effective in improving the characteristics as an oscillation circuit. The oscillation frequency of the Gunn diode 300g was able to operate at a higher frequency than that using a GaAs substrate.

Example 4
This embodiment will be described with reference to FIGS. FIG. 17 is a plan view schematically showing a specific configuration example of the semiconductor device 200 of the second embodiment.

  A semiconductor device 200 of this embodiment shown in FIG. 17 transmits a high frequency signal in the millimeter wave band. The driver amplifier for IF signal amplification, the FET mixer for up-conversion, and the transmission amplifier are on the same substrate. It is integrated on top.

  The output signal of the driver amplifier is once taken out of the semiconductor device 200 through the IF signal output terminal, and unnecessary signals are removed through a filter such as a dielectric resonator, and then introduced into the semiconductor device 200 from the IF signal input terminal again. The This output signal and the output from the Gunn diode 200g are used as local signals, and the high-frequency signal after up-conversion by an up-conversion FET mixer is further band-limited by a filter, amplified by a transmission amplifier, and spatially separated by a patch antenna. Radiates to.

  In this embodiment, a Fe-doped semi-insulating InP substrate is used as the substrate 1 of the semiconductor device 200, and all the filters and patch antennas are formed on the substrate 1. Further, a metal thin film serving as a ground plane is formed on the lower surface of the substrate 1 and used. The driver amplifier, the FET mixer, and the transmission amplifier are all configured using an HBT (heterobipolar transistor), and all correspond to the bipolar transistor 200t.

The bipolar transistor 200t includes an n ⁺ -InP layer as the n-type semiconductor layer 22, an n-InGaAs layer as the n-type semiconductor layer 23, a Zn-doped p ⁺ -InGaAs layer as the p-type semiconductor layer 24, and an n-semiconductor layer. 27 is an Si-doped n-InP layer (impurity concentration 5 × 10 ¹⁸ cm ⁻³ ), and the n + semiconductor layer 28 is an Si-doped n ⁺ -InP layer (impurity concentration 1 × 10 ¹⁹ cm ⁻³ ).

The Gunn diode 200g is a Si-doped n-InP layer (impurity concentration 5 × 10 ¹⁸ cm ⁻³ ) as the n − semiconductor layer 27 and a Si-doped n ⁺ −InP layer (impurity concentration 1 × 10 ¹⁹ cm ⁻³ ) as the n + semiconductor layer 28. Thus, the n-semiconductor layer 29 is an n-InGaAs layer (carrier density 1 × 10 ^{15 to} 1 × 10 ¹⁹ cm ⁻³ ), and the n + semiconductor layer 30 is an Si-doped n ⁺ -InP layer (impurity concentration 1 × 10 ¹⁹ cm ⁻³ ). Has been.

  The filter and patch antenna were formed using an Au thin film. The ohmic contact between the electrodes 25, 26, 31, 32 and 33 and the n + semiconductor layers 22, 24, 28 and 30 in the semiconductor device 200 is performed by using the AuGeNi layer to connect the electrodes 25, 26, 31, 32 and 33. The junction resistance was reduced by heat treatment at about 300 ° C. in a nitrogen atmosphere.

  In this embodiment, a Gunn diode that can oscillate at a high frequency, a driver amplifier for IF signal amplification, an FET mixer for up-conversion, a transmission amplifier, and the like are integrated on a single substrate. It was effective for miniaturization.

  Further, the semiconductor device 200 could be manufactured with good reproducibility when a plurality of identical circuits were produced. In particular, the operating frequency of the Gunn diode 200g can be designed with the film thickness of the n − semiconductor layer 29. For example, by setting the oscillation frequency to about 50 GHz to 90 GHz, it was possible to transmit a millimeter wave of 60 GHz band or 77 GHz band as a transmission signal.

  In this embodiment, since a plurality of semiconductor layers are epitaxially grown on a semi-insulating InP substrate, the crystallinity of each layer is equivalent to that of a single crystal material, which is effective in improving the characteristics as an oscillation circuit. The operation frequency of the Gunn diode 200g was higher than that using a GaAs substrate.

  The HBT is practically useful because it can produce an amplifier capable of high-frequency operation with respect to the HEMT even when using a photolithography technique with an alignment accuracy of about 1 micron. In this example, InGaAs was used for the base and InP was used for the emitter, but it was also effective to use a double heterostructure using GaAsSb for the base and InP for the collector and emitter.

  In addition, although the high frequency circuit whose high frequency transmission line is a microstrip line was demonstrated in Examples 1-4, this invention is not limited to this, The coplanar transmission line using an electroconductive thin film instead of a microstrip line Alternatively, a slot line may be used. In particular, since the coplanar transmission line does not have a ground surface on the lower surface of the substrate 1, there is no processing of the lower surface of the substrate 1 or a process for forming the ground surface, which is advantageous in reducing the manufacturing cost.

  The present invention is useful for a high-frequency device or the like that needs to operate in a microwave band, a millimeter wave band, or a terahertz frequency band.

FIG. 1 is a cross-sectional view showing a semiconductor device. FIG. 2 is a cross-sectional view schematically showing the operation of the Gunn diode. 3A to 3C are cross-sectional views illustrating a method for manufacturing a semiconductor device. 4A and 4B are cross-sectional views illustrating a method for manufacturing a semiconductor device. FIG. 5 is a cross-sectional view showing the semiconductor device. 6A to 6C are cross-sectional views illustrating a method for manufacturing a semiconductor device. 7A and 7B are cross-sectional views illustrating a method for manufacturing a semiconductor device. FIG. 8 is a cross-sectional view showing a semiconductor device. 9A to 9C are cross-sectional views illustrating a method for manufacturing a semiconductor device. 10A and 10B are cross-sectional views illustrating a method for manufacturing a semiconductor device. FIG. 11 is a cross-sectional view illustrating a semiconductor device. 12A to 12C are cross-sectional views illustrating a method for manufacturing a semiconductor device. 13A and 13B are cross-sectional views illustrating a method for manufacturing a semiconductor device. FIG. 14 is a plan view schematically illustrating a specific configuration example of the semiconductor device. FIG. 15 is a plan view schematically illustrating a specific configuration example of the semiconductor device. FIG. 16 is a plan view schematically illustrating a specific configuration example of the semiconductor device. FIG. 17 is a plan view schematically illustrating a specific configuration example of the semiconductor device. FIG. 18 is a diagram schematically showing the principle of generating a gun effect in a planar type Gunn diode. FIG. 19 is a diagram showing the relationship between electric field strength and electron traveling speed in a Gunn diode using n-type GaAs. FIG. 20 is a diagram illustrating conditions under which the cancer effect occurs. FIG. 21 is a diagram showing f0 in the most basic dipole mode. FIG. 22 is a diagram illustrating an example in which a Gunn diode is flip-chip mounted on a flat circuit board constituting a microstrip line.

Explanation of symbols

1 substrate 2, 4 n + semiconductor layer 2A n-type semiconductor layer 2A
3 n-semiconductor layer 5, 6, 11, 12, 13 electrode 7 n-type semiconductor layer 8 p-type semiconductor layer 9 n-semiconductor layer 9A n-type semiconductor layer 10 n + semiconductor layer 13 domains 14, 15, 35, 54, 55 , 76 Recesses 22, 23, 27A, 29A n-type semiconductor layer 24 p-type semiconductor layer 27, 29 n− semiconductor layer 28, 30 n + semiconductor layers 25, 26, 31, 32, 33 Electrode 41 Non-doped semiconductor layer 42 n-type semiconductor Layers 43 and 45 n + semiconductor layer 44 n-semiconductor layers 46, 47, 48, 49 Electrode 62A n-type semiconductor layers 62, 64 n + semiconductor layer 63 n-semiconductor layers 65, 66, 71, 72 Electrode 67 Non-doped semiconductor layer 68 n Type semiconductor layer 69 n + semiconductor layer 100, 200, 300, 400 Semiconductor device 100t, 200t Bipolar transistor 300t, 400t HEMT
100g, 200g, 300g, 400g Gunn diode

Claims (11)

A substrate having an oscillation element region and a transistor region;
An oscillation element formed on the oscillation element region;
A transistor formed in the transistor region;
A semiconductor device comprising:   A semiconductor device, further comprising: a high-frequency circuit unit formed on the substrate and connected to the oscillation element and the transistor. The semiconductor device according to claim 1,
The oscillation device is a semiconductor device, which is a Gunn diode composed of an n-type semiconductor layer formed of a direct transition type compound semiconductor having a zinc flash structure and a pair of electrodes. The semiconductor device according to claim 3.
The semiconductor device, wherein the n-type semiconductor layer is formed of one type of compound semiconductor selected from the group consisting of GaAs, InP, InSb, ZnSe, and CdTe, or a mixed crystal of at least two types of compound semiconductors. The semiconductor device according to claim 3.
The n-type semiconductor layer is a semiconductor device formed of GaInNAs. The semiconductor device according to claim 1,
The semiconductor device, wherein the transistor is a heterostructure field effect transistor. The semiconductor device according to claim 1,
The semiconductor device is a heterojunction bipolar transistor. A step (a) of sequentially forming a first semiconductor layer and a second semiconductor layer on a substrate having a transistor region and an oscillation element region by epitaxial growth;
(B) forming an oscillation element using the first semiconductor layer and the second semiconductor layer located on the oscillation element region after removing the second semiconductor layer located in the transistor region;
Forming a transistor using the first semiconductor layer located in the transistor region (c);
A method for manufacturing a semiconductor device, comprising: In the manufacturing method of the semiconductor device according to claim 8,
The second semiconductor layer is formed of one type of compound semiconductor selected from the group consisting of GaAs, InP, InSb, ZnSe, and CdTe, or an n-type semiconductor formed of a mixed crystal of at least two types of compound semiconductors. And
The method for manufacturing a semiconductor device, wherein the oscillation element is a Gunn diode. A step (a) of sequentially forming a first semiconductor layer and a second semiconductor layer on a substrate having a transistor region and an oscillation element region by epitaxial growth;
(B) forming a transistor using the first semiconductor layer and the second semiconductor layer located on the transistor region after removing the second semiconductor layer located on the oscillation element region;
Forming an oscillation element using the first semiconductor layer located in the oscillation element region (c);
A method for manufacturing a semiconductor device, comprising: In the manufacturing method of the semiconductor device according to claim 10,
The first semiconductor layer is formed of one type of compound semiconductor selected from the group consisting of GaAs, InP, InSb, ZnSe, and CdTe, or an n-type semiconductor formed of a mixed crystal of at least two types of compound semiconductors. And
The method for manufacturing a semiconductor device, wherein the oscillation element is a Gunn diode.

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