JP7165312B2 - Semiconductor device manufacturing method - Google Patents

Description

The present invention relates to a novel method of manufacturing a semiconductor device.

2. Description of the Related Art A sealing technique using a resin is generally used when manufacturing a semiconductor device used in an electronic device or the like. On the other hand, semiconductor chips used in electronic devices tend to be smaller and larger in capacity, and the problem of heat dissipation from semiconductor chips is becoming a serious problem. There is an increasing demand for a resin-encapsulated type semiconductor device that is improved and has high mounting reliability.

2. Description of the Related Art Conventionally, a mounted semiconductor device obtained by encapsulating a semiconductor device with resin has been known. In a conventional mounted semiconductor device, a connection electrode of the semiconductor device is formed by fixing the semiconductor device on the element mounting portion of a lead frame having an element mounting portion and a lead portion using an adhesive or the like and bonding a bonding wire. are electrically connected to the lead portions of the lead frame. Thereafter, by sealing the semiconductor device, bonding wires, etc. with a mold resin, a mounted semiconductor device having a predetermined shape is formed.

In Patent Document 1, in manufacturing a PIN diode mounted product having a semiconductor substrate, an I layer, and a p-type semiconductor region, a first electrode connected to the p-type semiconductor region is formed, and a second electrode connected to the semiconductor substrate as the N layer is formed. By forming two electrodes, die bonding and wire bonding are performed after manufacturing a PIN diode, and then a molding process is performed to seal the PIN diode and bonding wires with resin. Further, in Patent Document 2, each electrode of a diode in which an anode electrode as a first electrode is formed on one surface side of a flat semiconductor and a cathode electrode as a second electrode is formed on the other surface side of a flat semiconductor is disclosed. A mounted semiconductor device is manufactured by fixing lead frame terminals via solder and then sealing with resin, and productivity is improved by simultaneously sealing a plurality of diodes with resin. However, in the manufacturing method described in Patent Document 1 or Patent Document 2, after forming the first electrode, the formation of the second electrode is performed as it is. As a result, there is a problem that the adhesion between the semiconductor layer and the first electrode is lowered, and the electrical characteristics and reliability of the semiconductor device are adversely affected. Furthermore, there is also a problem that the resin is not sufficiently filled during resin sealing, resulting in incomplete filling or voids, which hinders reliability.

Therefore, an industrially useful manufacturing method has been eagerly awaited, which does not adversely affect the interface between the semiconductor layer and the electrode and which can manufacture a semiconductor device having good electrical characteristics and excellent reliability.

JP 2007-250813 A JP 2007-311518 A

SUMMARY OF THE INVENTION It is an object of the present invention to provide an industrially advantageous method for manufacturing a semiconductor device having good electrical characteristics and excellent reliability.

The inventors of the present invention conducted intensive studies to achieve the above object, and found that at least a first electrode forming step of forming a first electrode on a semiconductor layer formed on a substrate and a first electrode forming step of the semiconductor layer. a second electrode forming step of forming a second electrode on part or all of the surface on which the electrode is not formed, wherein the semiconductor layer and the first electrode are formed after the first electrode forming step; After sealing the electrodes with resin, the substrate is removed from the semiconductor layer , and then the second electrode forming step is performed. , found that a semiconductor device having good electrical characteristics and excellent reliability can be produced, and found that such a production method can solve the above-described conventional problems at once. Further, according to such a manufacturing method, even if a semiconductor material such as gallium oxide that is difficult to peel off from the underlying substrate is used as the semiconductor layer, after the first electrode is formed, , the semiconductor layer can be easily peeled off from the substrate.
Moreover, after obtaining the above knowledge, the inventors of the present invention completed the present invention through further studies.

Specifically, the present invention relates to the following inventions.
[1] At least a first electrode forming step of forming a first electrode on a semiconductor layer formed on a substrate; 2, wherein after the first electrode forming step, the semiconductor layer and the first electrode are sealed with a resin, and then the substrate is formed. is removed from the semiconductor layer , and then a step of forming a second electrode is performed.
[2] The production method according to [1], wherein the resin is a thermosetting resin.
[3] The manufacturing method according to [1] or [2], wherein the semiconductor layer contains an oxide semiconductor as a main component.
[4] The manufacturing method according to [3], wherein the oxide semiconductor contains one or more metals selected from aluminum, indium and gallium.
[5] The manufacturing method according to any one of [3] or [4], wherein the oxide semiconductor has a corundum structure.
[6] The manufacturing method according to any one of [1] to [5], wherein the second electrode is formed on part or all of the surface of the semiconductor layer opposite to the first electrode.
[7] The manufacturing method according to any one of [1] to [6], wherein the first electrode is a Schottky electrode.
[8] The manufacturing method according to any one of [1] to [7], wherein the second electrode is an ohmic electrode.
[9] A semiconductor device manufactured by the manufacturing method according to any one of [1] to [8].
[10] A semiconductor system comprising a semiconductor device, wherein the semiconductor device is the semiconductor device according to [9].

According to the manufacturing method of the present invention, it is possible to manufacture a semiconductor device having excellent electrical characteristics and excellent reliability, which is industrially advantageous.

1 is a schematic configuration diagram of a mist CVD apparatus used for forming an n + -type semiconductor layer in Examples. FIG. 1 is a schematic configuration diagram of a mist CVD apparatus used for forming an n− type semiconductor layer in Examples. FIG. 1 is a diagram schematically showing a preferred example of a Schottky barrier diode (SBD) of the present invention; FIG. 1 is a diagram schematically showing a preferred example of a Schottky barrier diode (SBD) of the present invention; FIG. 1 is a diagram schematically showing a preferred example of a power supply system; FIG. 1 is a diagram schematically showing a preferred example of a system device; FIG. FIG. 2 is a diagram schematically showing a preferred example of a power supply circuit diagram of a power supply device;

A method of manufacturing a semiconductor device according to the present invention comprises a first electrode forming step of forming a first electrode on a semiconductor layer formed on a substrate; a second electrode forming step of forming a second electrode on part or all of the semiconductor device, wherein the semiconductor layer and the first electrode are sealed with a resin after the first electrode forming step; After that, the substrate is removed from the semiconductor layer , and then a second electrode forming step is performed. The semiconductor device may be mounted before or after mounting.

(First electrode forming step)
In the first electrode forming step, a first electrode is formed on the semiconductor layer. The semiconductor layer is not particularly limited as long as it contains a semiconductor, and may be a known layer. Examples of the semiconductor layer include simple elements such as silicon and germanium, compounds containing elements of Groups 13 to 15 of the periodic table, metal oxides, metal sulfides, metal selenides, metal nitrides, and the like. A semiconductor layer containing Examples of compounds having elements of groups 13 to 15 of the periodic table include SiC, AlN, GaN, InN, GaAs, and InP. Examples of the metal oxide include titanium oxide (titanium oxide), tin oxide, zinc oxide, iron oxide, tungsten oxide, zirconium oxide, hafnium oxide, and strontium oxide. oxides, indium, cerium, yttrium, lanthanum, vanadium, niobium oxides, tantalum oxides, and the like. Examples of the metal sulfide include cadmium sulfide, zinc sulfide, lead sulfide, silver sulfide, antimony or bismuth sulfide, and the like. Examples of the metal selenide include cadmium or lead selenide, gallium-arsenic or copper-indium selenide, and the like. Examples of the metal nitrides include gallium nitrides and titanium nitrides. The thickness of the semiconductor layer is not particularly limited as long as it does not interfere with the object of the present invention, but it is preferably 5 nm to 500 μm, more preferably 10 nm to 100 μm. Moreover, the semiconductor layer may be a single layer, or may be two or more layers. Further, the semiconductor layer may be any of an n+ type semiconductor layer, an n− type semiconductor layer, an n type semiconductor layer, and a p type semiconductor layer. In the present invention, the semiconductor layer is preferably two or more layers, and preferably one or more selected from an n + type semiconductor layer, an n− type semiconductor layer and an n type semiconductor layer. It is more preferably two or more layers selected from an n+ type semiconductor layer, an n− type semiconductor layer and an n type semiconductor layer. The means for forming the semiconductor layer is not particularly limited as long as it does not interfere with the object of the present invention, and may be known means. Examples of the forming means include CVD, MOCVD, MOVPE, mist CVD, MBE, HVPE, and pulse growth. In the present invention, the forming means is mist CVD. It is preferable to have

In the present invention, the semiconductor layer preferably contains an oxide semiconductor as a main component. The oxide semiconductor preferably contains indium, gallium, or aluminum, since a semiconductor device with more excellent semiconductor characteristics can be obtained, more preferably contains an InAlGaO-based semiconductor, and most preferably contains at least gallium. Note that, for example, when the crystalline oxide semiconductor is α-Ga ₂ O ₃ , the “main component” means α-Ga ₂ O at a ratio of 0.5 or more to the atomic ratio of gallium in the metal element in the film. If ₃ is included, that's fine. In the present invention, the atomic ratio of gallium in the metal elements in the film is preferably 0.7 or more, more preferably 0.8 or more.

The semiconductor layer may be one with a substrate or one separated from the substrate. In the present invention, a semiconductor layer with a substrate is used as the semiconductor layer. It is preferable to manufacture a vertical element (vertical device) as a device, because a semiconductor device with higher reliability can be obtained.

The first electrode is not particularly limited as long as it has conductivity and functions as an electrode, and may be a known electrode. Materials constituting the first electrode include, for example, Al, Mo, Co, Zr, Sn, Nb, Fe, Cr, Ta, Ti, Au, Pt, V, Mn, Ni, Cu, Hf, W, Ir , metals such as Zn, In, Pd, Nd or Ag or alloys thereof, conductive metal oxides such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), zinc indium oxide (IZO), polyaniline, Examples include organic conductive compounds such as polythiophene or polypyrrole, or mixtures thereof. In the present invention, the first electrode preferably contains a metal or a conductive metal oxide. Moreover, in the present invention, the first electrode is preferably a Schottky electrode. When the first electrode is a Schottky electrode, it preferably comprises a metal of Groups 4, 6, 11 or 13 of the Periodic Table. Examples of metals belonging to Group 4 of the periodic table include titanium (Ti), zirconium (Zr), and hafnium (Hf), with Ti being preferred. Examples of metals belonging to Group 6 of the periodic table include chromium (Cr), molybdenum (Mo), and tungsten (W), among which Cr and Mo are preferred. Examples of metals belonging to Group 11 of the periodic table include copper (Cu), silver (Ag), and gold (Au), among which Au is preferred. Examples of metals belonging to Group 13 of the periodic table include aluminum (Al), gallium (Ga), and indium (In), among which Al is preferred. Examples thereof include copper (Cu), silver (Ag), gold (Au), etc. Among them, Au is preferable. In addition, the first electrode may further contain other metals, and the other metals are not particularly limited as long as they do not impede the object of the present invention. metals (Ni, Pd, Pt), and more preferably Pt. Also, the first electrode may be a single layer, or may include two or more layers.

The thickness of the first electrode is not particularly limited as long as it does not hinder the object of the present invention, but it is preferably 10 nm to 100 μm, more preferably 10 nm to 10 μm.

The means for forming the first electrode is not particularly limited as long as it does not interfere with the object of the present invention, and known means can be used. Examples of means for forming the first electrode include a mist CVD method, a sputtering method, a CVD method (vapor deposition method), an SPD method (spray pyrolysis deposition method), and a vapor deposition method.

After forming the first electrode on the semiconductor layer, the semiconductor layer and the first electrode are sealed with a resin. More specifically, after forming the first electrode on the semiconductor layer, part or all of the semiconductor layer and part or all of the first electrode are sealed with resin. In the present invention, the resin-sealed portion of the semiconductor layer is preferably part or all of the surface of the semiconductor layer on the side where the first electrode is formed. More preferably, it is the entire surface of the semiconductor layer. The resin-sealed portion of the first electrode preferably includes the first electrode surface on the side where the semiconductor layer is formed, and includes the first electrode surface on the side where the semiconductor layer is formed and the side surface thereof. is more preferred, and most preferred is all exposed surfaces of the first electrode. In the case where the resin-sealed portion of the first electrode is the entire exposed surface of the first electrode, the first electrode is partially or wholly exposed by polishing or the like after the resin-sealing. is preferred.

The resin is not particularly limited as long as it does not interfere with the object of the present invention, and may be a known resin used for encapsulating semiconductor devices. In the present invention, the resin is preferably a thermosetting resin. Examples of the thermosetting resins include epoxy resins, modified epoxy resins, silicone resins, modified silicone resins, acrylate resins, urethane resins, one or more of these, or mixtures thereof. In the present invention, the thermosetting resin is preferably epoxy resin or modified epoxy resin. Examples of the modified epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolak type epoxy resin, bisphenol A novolak type epoxy resin, bisphenol F Novolac-type epoxy resin, stilbene-type epoxy resin, triazine skeleton-containing epoxy resin, fluorene skeleton-containing epoxy resin, triphenol phenol-methane-type epoxy resin, biphenyl-type epoxy resin, xylylene-type epoxy resin, biphenylaralkyl-type epoxy resin, naphthalene-type epoxy resin , dicyclopentadiene type epoxy resins, alicyclic epoxy resins, diglycidyl ether compounds of polyfunctional phenols and polycyclic aromatics such as anthracene, and phosphorus-containing epoxy resins obtained by introducing a phosphorus compound into these, or one of these species, two or more species, or a mixture thereof. In addition, in the present invention, as the resin, a certain amount of resin other than the resins exemplified above may be used in combination with the resins exemplified above depending on the purpose.

The thickness of the resin is preferably 10 μm or more, more preferably 10 μm to 3000 μm. If the thickness is 10 μm or more, the thickness is sufficient for sealing, and it is preferable because it is possible to suppress the occurrence of poor filling properties due to excessive thinness. The upper limit of the thickness of the resin is not particularly limited, and the resin may be cured after filling the first electrode with the resin. A part or the whole is exposed by known means such as polishing. In the present invention, if the thickness of the resin is 3000 μm or less, it is preferable because it becomes easy to expose part or all of the first electrode by polishing or the like after sealing with the resin, and the thickness is preferably 1500 μm or less. preferable.

The resin sealing means is not particularly limited as long as it does not interfere with the object of the present invention, and may be a known sealing means. Examples of the means for sealing the resin include means for sealing by curing the resin by heating after impregnation (immersion, coating, spraying, pressing with a resin sheet, etc.).

Further, in the present invention, when a vertical device is manufactured as the semiconductor device, one surface of the semiconductor layer is used as the first electrode forming portion and the resin sealing portion, and the other surface is used as the second electrode forming portion. An electrode forming portion is preferable. Further, when manufacturing a horizontal device, one surface of the semiconductor layer is preferably used as a first electrode formation portion, a resin sealing portion, and a second electrode formation portion. In order to make one surface the first electrode formation portion, the resin sealing portion, and the second electrode formation portion, for example, a protective film is formed on the second electrode formation portion of the one surface of the semiconductor layer. After providing, resin sealing is performed, and then the protective film is removed.

(Second electrode forming step)
In the second electrode forming step, after the resin sealing step, a second electrode is formed on part or all of the surface of the semiconductor layer on which the first electrode is not formed.

The second electrode is not particularly limited as long as it has conductivity and functions as an electrode, and may be a known electrode. Materials constituting the second electrode include, for example, Al, Mo, Co, Zr, Sn, Nb, Fe, Cr, Ta, Ti, Au, Pt, V, Mn, Ni, Cu, Hf, W, Ir , metals such as Zn, In, Pd, Nd or Ag or alloys thereof, metal oxide conductive films such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), zinc indium oxide (IZO), polyaniline, Examples include organic conductive compounds such as polythiophene or polypyrrole, or mixtures thereof. In the present invention, the second electrode preferably contains a metal or a conductive metal oxide. Moreover, in the present invention, the second electrode is preferably an ohmic electrode. When the second electrode is an ohmic electrode, it preferably contains a metal of Group 4 or Group 11 of the Periodic Table. The metal of Group 4 or Group 11 of the periodic table may be the same as the metal contained in the first electrode. Also, the second electrode may further contain another metal. Also, the second electrode may be a single layer, or may include two or more layers. Also, the metal forming the second electrode may be an alloy.

The thickness of the second electrode is not particularly limited as long as it does not interfere with the object of the present invention, but it is preferably 10 nm to 100 μm, more preferably 10 nm to 10 μm.

The means for forming the second electrode is not particularly limited as long as it does not interfere with the object of the present invention, and known means can be used. Examples of means for forming the first electrode include a mist CVD method, a sputtering method, a CVD method (vapor deposition method), an SPD method (spray pyrolysis deposition method), and a vapor deposition method.

In the present invention, when the first electrode is formed on the semiconductor layer with the substrate, the second electrode is directly formed on part or all of the surface of the semiconductor layer on which the first electrode is not formed. may be formed, or the second electrode may be formed after using known means such as peeling the semiconductor layer from the substrate. The present invention can also be suitably applied to a semiconductor layer that is difficult to peel off from a substrate. Separation is preferable because the substrate can be separated from the semiconductor layer simply and easily without adversely affecting the interface between the semiconductor layer and the first electrode.

The part where the second electrode is formed may be part or all of the surface of the semiconductor layer on which the first electrode is not formed. In the present invention, a second electrode is formed on part or all of the surface of the semiconductor layer opposite to the first electrode, and a vertical element (vertical device) is manufactured as the semiconductor device. is preferable because a semiconductor device with more excellent reliability can be obtained, and it is more preferable that the semiconductor layer contains a wide bandgap semiconductor because the characteristics as a power device are more excellent. .

Further, the semiconductor device may be a mounted semiconductor device. In the mounted semiconductor device, after the first electrode forming step, the semiconductor layer and the first electrode are sealed with a first resin. is obtained by sealing the first resin and the second electrode. Here, the first resin and the second resin are preferably thermosetting resins, and the thermosetting resins may be the same as the thermosetting resins exemplified above as the thermosetting resins. The sealing method may be the same as the sealing method exemplified as the resin sealing method.

INDUSTRIAL APPLICABILITY According to the manufacturing method of the present invention, it is possible to industrially manufacture a semiconductor device having good electrical characteristics and excellent reliability. Moreover, the semiconductor device obtained by the manufacturing method of the present invention is useful for various purposes, especially for power devices. Semiconductor devices can be classified into horizontal devices in which electrodes are formed on one side of a semiconductor layer (horizontal devices) and vertical devices in which electrodes are formed on both front and back sides of a semiconductor layer (vertical devices). In the present invention, the semiconductor device can be suitably used as both a horizontal device and a vertical device, and among others, it is preferably used as a vertical device. Examples of the semiconductor device include Schottky barrier diodes (SBD), metal semiconductor field effect transistors (MESFET), high electron mobility transistors (HEMT), metal oxide semiconductor field effect transistors (MOSFET), static induction transistors ( SIT), junction field effect transistor (JFET), insulated gate bipolar transistor (IGBT) or light emitting diode, a module equipped with these, or an electronic device equipped with these or its parts. In the present invention, the semiconductor device is preferably an SBD, MOSFET, SIT, JFET or IGBT, a module in which these are mounted, or an electronic device or a component thereof provided with these, and the SBD, MOSFET or SIT, these is more preferably a module mounted with or an electronic device or a component thereof equipped with these, and most preferably an SBD, a module mounted with an SBD, or an electronic device or a component thereof equipped with an SBD.

(SBD)
FIG. 3 shows a preferred example of a Schottky barrier diode (SBD) according to the invention. The SBD of FIG. 3 includes an n− type semiconductor layer 101a, an n+ type semiconductor layer 101b, a Schottky electrode 105a and an ohmic electrode 105b.
Schottky electrodes and ohmic electrodes can be formed by known means such as vacuum deposition or sputtering. More specifically, for example, when forming a Schottky electrode, the first electrode is laminated, and the first electrode is patterned using a photolithography technique.
In the present invention, it is preferable to use the first electrode as the Schottky electrode 105a and the second electrode as the ohmic electrode 105b.

When a reverse bias is applied to the SBD of FIG. 3, a depletion layer (not shown) spreads in the n-type semiconductor layer 101a, resulting in a high withstand voltage SBD. Further, when a forward bias is applied, electrons flow from the ohmic electrode 105b to the Schottky electrode 105a. Thus, the SBD using the laminated structure is excellent for high withstand voltage and large current, has good Schottky characteristics, has a high switching speed, and is excellent in withstand voltage and reliability.

FIG. 4 shows another preferred example of a Schottky barrier diode (SBD) according to the present invention. The SBD of FIG. 4 further includes an insulator layer 104 in addition to the structure of the SBD of FIG. More specifically, it comprises an n− type semiconductor layer 101a, an n+ type semiconductor layer 101b, a Schottky electrode 105a, an ohmic electrode 105b and an insulator layer 104. FIG.

Examples of the material of the insulator layer 104 include GaO, AlGaO, _InAlGaO , _AlInZnGaO4 , AlN, _Hf2O3 , SiN, SiON, _Al2O3 , MgO, _{GdO , SiO2} or _Si3N4 . However, in the present invention, it preferably has a corundum structure. By using an insulator having a corundum structure for the insulator layer, it is possible to satisfactorily exhibit the function of semiconductor characteristics at the interface. The insulator layer 104 is provided between the n− type semiconductor layer 101 and the Schottky electrode 105a. The insulator layer can be formed by known means such as sputtering, vacuum deposition, or CVD.
Other configurations are the same as those of the SBD shown in FIG.
The SBD of FIG. 4 has even better insulation characteristics and higher current controllability than the SBD of FIG.

In the present invention, it is preferable that the SBD is further subjected to resin sealing and mounted, and such a mounted SBD is also included in the semiconductor device of the present invention. The mounting means is not particularly limited, and may be a known mounting means. As the resin used for resin sealing, the same resin as the resin used in the resin sealing step and exemplified above can be used.

A semiconductor device obtained by the manufacturing method of the present invention is used, for example, in a system using a power supply device. The power supply device can be manufactured by connecting the semiconductor device to a wiring pattern or the like using known means. FIG. 5 shows an example of a power supply system. FIG. 5 shows a power supply system using a plurality of power supply units and control circuits. The power supply system can be used in a system unit in combination with an electronic circuit, as shown in FIG. An example of a power supply circuit diagram of the power supply is shown in FIG. FIG. 7 shows a power supply circuit of a power supply device consisting of a power circuit and a control circuit. DC voltage is switched at a high frequency by an inverter (configured with MOSFETs A to D), converted to AC, and then insulated and transformed by a transformer. , rectification by rectification MOSFETs (A to B'), smoothing by DCL (smoothing coils L1, L2) and capacitors, and output of DC voltage. At this time, the voltage comparator compares the output voltage with the reference voltage, and the PWM control circuit controls the inverter and the rectifying MOSFET so as to obtain a desired output voltage.

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these.

(Example 1)
1. Formation of n+ type semiconductor layer 1-1. Film Forming Apparatus A mist CVD apparatus 1 used in this example will be described with reference to FIG. The mist CVD apparatus 1 includes a carrier gas source 2a for supplying a carrier gas, a flow control valve 3a for adjusting the flow rate of the carrier gas sent from the carrier gas source 2a, and a carrier gas (dilution) for supplying the carrier gas (dilution). a dilution) source 2b, a flow control valve 3b for adjusting the flow rate of the carrier gas (dilution) sent from the carrier gas (dilution) source 2b, a mist generation source 4 containing a raw material solution 4a, and water 5a. a container 5 in which the It is equipped with a hot plate 8 installed and an exhaust port 11 for discharging mist, droplets and exhaust gas after thermal reaction. A substrate 10 is placed on the hot plate 8 .

1-2. Preparation of raw material solution Tin bromide was mixed with a 0.1 M gallium bromide aqueous solution to adjust the aqueous solution so that the atomic ratio of tin to gallium was 1:0.08. 10% of the ratio was contained and this was made into the raw material solution.

1-3. Film formation preparation 1-2 above. The raw material solution 4 a obtained in 1. was accommodated in the mist generating source 4 . Next, a sapphire substrate was placed on the hot plate 8 as the substrate 10, and the hot plate 8 was operated to raise the temperature in the deposition chamber 7 to 450.degree. Next, the flow control valves 3a and 3b are opened to supply the carrier gas from the carrier gas supply means 2a and 2b, which are carrier gas sources, into the film forming chamber 7, and the atmosphere of the film forming chamber 7 is sufficiently filled with the carrier gas. After the substitution, the carrier gas flow rate was adjusted to 2.0 L/min, and the carrier gas (dilution) flow rate was adjusted to 0.5 L/min. Nitrogen was used as a carrier gas.

1-4. Formation of Crystalline Oxide Semiconductor Film Next, the ultrasonic oscillator 6 is vibrated at 2.4 MHz, and the vibration is propagated through the water 5a to the raw material solution 4a, thereby atomizing the raw material solution 4a to form a mist 4b. was generated. The mist 4b is introduced into the film formation chamber 7 through the supply pipe 9 by the carrier gas, and the mist undergoes a thermal reaction in the film formation chamber 7 at 450° C. under atmospheric pressure to form the substrate 10. A film was formed on top. The film thickness was 9.0 μm, and the film formation time was 270 minutes.

1-5. Evaluation Using an XRD diffractometer, the above 1-4. When the phase of the obtained film was identified, the obtained film was α-Ga ₂ O ₃ .

2. Formation of n-type semiconductor layer 2-1. Film Forming Apparatus The mist CVD apparatus 19 used in the examples will be described with reference to FIG. The mist CVD apparatus 19 includes a susceptor 21 on which a substrate 20 is placed, carrier gas supply means 22a for supplying carrier gas, and a flow control valve 23a for adjusting the flow rate of the carrier gas sent out from the carrier gas supply means 22a. , a carrier gas (dilution) supply means 22b for supplying a carrier gas (dilution), a flow control valve 23b for adjusting the flow rate of the carrier gas sent from the carrier gas (dilution) supply means 22b, and a raw material solution 24a. a container 25 containing water 25a; an ultrasonic oscillator 26 attached to the bottom surface of the container 25; and a heater 28 installed in the The susceptor 21 is made of quartz, and the surface on which the substrate 20 is placed is inclined from the horizontal plane. By making both the supply pipe 27 and the susceptor 21, which are the film forming chambers, out of quartz, the film formed on the substrate 20 is prevented from being contaminated with impurities originating from the apparatus.

2-2. Preparation of Raw Material Solution A 0.1 M gallium bromide aqueous solution was made to contain 10% by volume of deuterium bromide, and this was used as a raw material solution.

2-3. Film formation preparation 2-2 above. The raw material solution 24 a obtained in 1. was accommodated in the mist generation source 24 . Next, as the substrate 20, an n+ type semiconductor film separated from the sapphire substrate was placed on the susceptor 21, and the heater 28 was operated to raise the temperature in the film forming chamber 27 to 460.degree. Next, the flow control valves 23a and 23b are opened to supply the carrier gas from the carrier gas supply means 22a and 22b, which are carrier gas sources, into the film forming chamber 27, and the atmosphere of the film forming chamber 27 is sufficiently filled with the carrier gas. After the substitution, the carrier gas flow rate was adjusted to 1.0 L/min, and the carrier gas (diluted) flow rate was adjusted to 0.5 L/min. Oxygen was used as a carrier gas.

2-4. Semiconductor Film Formation Next, the ultrasonic oscillator 26 was vibrated at 2.4 MHz, and the vibration was propagated through the water 25a to the raw material solution 24a, thereby atomizing the raw material solution 24a to generate mist. This mist was introduced into the film formation chamber 27 by the carrier gas, and the mist reacted in the film formation chamber 27 at 460° C. under atmospheric pressure to form a semiconductor film on the substrate 20 . The film thickness was 1.0 μm, and the film formation time was 40 minutes.

2-5. Evaluation Using an XRD diffractometer, the above 2-4. When the phase of the obtained film was identified, the obtained film was α-Ga ₂ O ₃ .

3. Formation of First Electrode (Schottky Electrode) As a Schottky electrode, a Cr layer and an Al layer were deposited on the n-type semiconductor layer by electron beam deposition. The thickness of the Cr layer was 50 nm, and the thickness of the Al layer was 5000 nm.

4. Resin Encapsulation An epoxy resin (manufactured by Kyocera Corporation) was used to seal the n+ type semiconductor layer, the n− type semiconductor layer, and the first electrode. The resin impregnation is performed by pressing an epoxy resin sheet against the n + type semiconductor layer, the n − type semiconductor layer, and the first electrode while heating, and the resin is cured by applying pressure (about 0.5 tons). It was carried out by heating at a temperature of 150° C. for 140 minutes and at a temperature of 180° C. for 150 minutes.

5. Formation of Second Electrode (Ohmic Electrode) After removing the sapphire substrate by polishing, a Ti layer and an Au layer were laminated as ohmic electrodes on the n + -type semiconductor layer by electron beam deposition. The thickness of the Ti layer was 70 nm, and the thickness of the Au layer was 30 nm.

6. IV Measurement After exposing the first electrode buried in the resin by polishing, the obtained semiconductor device was subjected to IV measurement.

(Comparative example 1)
Reversing the order of forming the n+ type semiconductor layer and the n− type semiconductor layer, reversing the order of forming the first electrode (Schottky electrode) and the second electrode (ohmic electrode), and resin A semiconductor device was fabricated in the same manner as in Example 1, except that sealing was not performed. However, when the sapphire substrate was peeled off, peeling occurred at the interface between the second electrode (ohmic electrode) and the n + -type semiconductor layer, making IV measurement impossible.

(Examples 2-5)
A semiconductor device was obtained in the same manner as in Example 1, except that an epoxy resin sheet having a thickness shown in Table 1 was used. The resulting semiconductor device was evaluated for voids, protrusion embedding properties, warpage, cracking during curing, cracking in post-processes, flatness, workability, and reproducibility (evaluated by fabricating a semiconductor device under the same conditions). . Table 1 shows the evaluation results. In Table 1, "○" indicates no problem, "Δ" indicates a partial problem, and "x" indicates an overall problem. In addition, among those with no problem, those exhibiting excellent properties are indicated by ".circleincircle.."

The method of manufacturing a semiconductor device according to the present invention is industrially advantageous and can manufacture a semiconductor device having good electrical characteristics and excellent reliability. , industrial materials, etc.

1 mist CVD apparatus 2a carrier gas source
2b Carrier gas (dilution) source 3a Flow control valve 3b Flow control valve 4 Mist source 4a Raw material solution 4b Mist 5 Container 5a Water 6 Ultrasonic vibrator 7 Film formation chamber 8 Hot plate 9 Supply pipe 10 Substrate 11 Exhaust port 19 Mist CVD device 20 substrate 21 susceptor 22a carrier gas supply means 22b carrier gas (diluted) supply means 23a flow control valve 23b flow control valve 24 mist generation source 24a raw material solution 25 container 25a water 26 ultrasonic vibrator 27 supply pipe 28 heater 29 exhaust Port 101a n− type semiconductor layer 101b n+ type semiconductor layer 104 insulator layer 105a Schottky electrode 105b ohmic electrode

Claims (8)

At least a first electrode forming step of forming a first electrode on a semiconductor layer formed on a substrate, and a second electrode formed on part or all of the surface of the semiconductor layer where the first electrode is not formed forming a second electrode forming step, wherein after the first electrode forming step, the semiconductor layer and the first electrode are sealed with a resin, and then the substrate is formed with the semiconductor removing from the layer, then performing a second electrode forming step;
The substrate is a sapphire substrate,
A method of manufacturing a semiconductor device , wherein the semiconductor layer has a corundum structure and contains an oxide semiconductor containing at least gallium . 2. The manufacturing method according to claim 1, wherein the resin is a thermosetting resin. 3. The manufacturing method according to claim 1, wherein the semiconductor layer contains the oxide semiconductor as a main component. The manufacturing method according to any one of claims 1 to 3 , wherein the second electrode is formed on part or all of the surface of the semiconductor layer opposite to the first electrode. The manufacturing method according to any one of claims 1 to 4 , wherein the first electrode is a Schottky electrode. The manufacturing method according to any one of claims 1 to 5 , wherein the second electrode is an ohmic electrode. A semiconductor device manufactured by the manufacturing method according to any one of claims 1 to 6 . A semiconductor system comprising a semiconductor device, wherein said semiconductor device is the semiconductor device according to claim 7 .

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