WO2010047280A1 - バイポーラトランジスタ - Google Patents
バイポーラトランジスタ Download PDFInfo
- Publication number
- WO2010047280A1 WO2010047280A1 PCT/JP2009/067907 JP2009067907W WO2010047280A1 WO 2010047280 A1 WO2010047280 A1 WO 2010047280A1 JP 2009067907 W JP2009067907 W JP 2009067907W WO 2010047280 A1 WO2010047280 A1 WO 2010047280A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- layer
- bipolar transistor
- collector
- base
- nitride semiconductor
- Prior art date
Links
- 239000004065 semiconductor Substances 0.000 claims abstract description 49
- 150000004767 nitrides Chemical class 0.000 claims abstract description 44
- 239000000758 substrate Substances 0.000 claims abstract description 42
- 239000013078 crystal Substances 0.000 claims abstract description 21
- 239000000203 mixture Substances 0.000 claims description 112
- 230000007423 decrease Effects 0.000 claims description 9
- 229910002704 AlGaN Inorganic materials 0.000 description 100
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 82
- 229910002601 GaN Inorganic materials 0.000 description 81
- 230000005684 electric field Effects 0.000 description 42
- 230000015556 catabolic process Effects 0.000 description 28
- 230000010287 polarization Effects 0.000 description 26
- 238000010586 diagram Methods 0.000 description 24
- 238000009826 distribution Methods 0.000 description 24
- 239000000463 material Substances 0.000 description 20
- 230000000694 effects Effects 0.000 description 12
- 230000006911 nucleation Effects 0.000 description 10
- 238000010899 nucleation Methods 0.000 description 10
- 229910004298 SiO 2 Inorganic materials 0.000 description 9
- 238000004519 manufacturing process Methods 0.000 description 9
- 230000003247 decreasing effect Effects 0.000 description 6
- 238000005530 etching Methods 0.000 description 6
- 239000010931 gold Substances 0.000 description 6
- 238000000034 method Methods 0.000 description 6
- 229910052782 aluminium Inorganic materials 0.000 description 5
- 239000010936 titanium Substances 0.000 description 5
- 239000012535 impurity Substances 0.000 description 4
- 229910052738 indium Inorganic materials 0.000 description 4
- 238000001020 plasma etching Methods 0.000 description 4
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 3
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 3
- 238000005229 chemical vapour deposition Methods 0.000 description 3
- 239000000460 chlorine Substances 0.000 description 3
- 238000009792 diffusion process Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000011777 magnesium Substances 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 238000000059 patterning Methods 0.000 description 3
- 238000005036 potential barrier Methods 0.000 description 3
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010955 niobium Substances 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 229910010271 silicon carbide Inorganic materials 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 238000000137 annealing Methods 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 229910052790 beryllium Inorganic materials 0.000 description 1
- ATBAMAFKBVZNFJ-UHFFFAOYSA-N beryllium atom Chemical compound [Be] ATBAMAFKBVZNFJ-UHFFFAOYSA-N 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 238000005468 ion implantation Methods 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 238000002488 metal-organic chemical vapour deposition Methods 0.000 description 1
- 229910052750 molybdenum Inorganic materials 0.000 description 1
- 239000011733 molybdenum Substances 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 229910052758 niobium Inorganic materials 0.000 description 1
- GUCVJGMIXFAOAE-UHFFFAOYSA-N niobium atom Chemical compound [Nb] GUCVJGMIXFAOAE-UHFFFAOYSA-N 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
- 239000010980 sapphire Substances 0.000 description 1
- 235000012239 silicon dioxide Nutrition 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 238000001947 vapour-phase growth Methods 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
- H01L29/70—Bipolar devices
- H01L29/72—Transistor-type devices, i.e. able to continuously respond to applied control signals
- H01L29/73—Bipolar junction transistors
- H01L29/737—Hetero-junction transistors
- H01L29/7371—Vertical transistors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/04—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their crystalline structure, e.g. polycrystalline, cubic or particular orientation of crystalline planes
- H01L29/045—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their crystalline structure, e.g. polycrystalline, cubic or particular orientation of crystalline planes by their particular orientation of crystalline planes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
- H01L29/12—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed
- H01L29/20—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by the materials of which they are formed including, apart from doping materials or other impurities, only AIIIBV compounds
- H01L29/2003—Nitride compounds
Definitions
- the present invention relates to a bipolar transistor, and more particularly to a bipolar transistor containing a group III nitride semiconductor as a main material.
- FIG. 1 is a cross-sectional view illustrating a typical bipolar transistor configuration.
- Such bipolar transistors are, for example, L. S. McCarthy et. al. "AlGaN / GaN Heterojunction Bipolar Transistor", IEEE Electron Devices Letters, Vol. 20, no. 6, pp. 277, (1999).
- a bipolar transistor includes a sapphire substrate 100, a sub-collector layer 103 made of high-concentration n-type GaN, a collector layer 104 made of low-concentration n-type GaN, a base layer 105 made of p-type GaN, and n-type Al 0.1.
- An emitter layer 106 made of Ga 0.9 N is provided. The crystal growth direction with respect to the substrate surface is parallel to the [0001] direction.
- An emitter electrode 10E is formed in contact with the n-type AlGaN emitter layer 106, a base electrode 10B is formed in contact with the p-type GaN base layer 105, and a collector electrode 10C is formed in contact with the n-type GaN subcollector layer 103.
- a p-type nitride semiconductor structure and a bipolar transistor are disclosed in WO 2004/061971 (corresponding US application: US 2005/224831 (A1)).
- a p-type nitride semiconductor layer containing In that has been regrown is provided on a p-type nitride semiconductor that has been processed by etching.
- JP-A-2006-128554 discloses a bipolar transistor and a manufacturing method thereof.
- This bipolar transistor has a first semiconductor layer, a second semiconductor layer, and a third semiconductor layer.
- an insulating film having an opening is formed under the second semiconductor layer, and a part of the first semiconductor layer is formed in contact with the lower part of the insulating film.
- JP 2008-4779 A discloses a nitride semiconductor bipolar transistor and a method for manufacturing a nitride semiconductor bipolar transistor.
- a nitride semiconductor layer formed in contact with an emitter electrode or a collector electrode is composed of an InAlGaN quaternary mixed crystal.
- FIG. 2 is an energy band diagram of the bipolar transistor shown in FIG.
- This energy band diagram shows a case where a forward bias is applied between the base and the emitter and a reverse bias is applied between the base and the collector in the bipolar transistor shown in FIG.
- L-M (LM) valley there is an L-M (LM) valley and a second ⁇ valley on the high energy side by about 2.0 eV from the bottom of the conduction band of GaN, that is, the gamma ( ⁇ ) valley.
- LM L-M
- ⁇ valley a second ⁇ valley on the high energy side by about 2.0 eV from the bottom of the conduction band of GaN, that is, the gamma ( ⁇ ) valley.
- FIG. 2 these are collectively referred to as “upper valley” (indicated by dotted lines in the figure).
- the electric field strength becomes maximum near the interface between the base layer 105 and the collector layer 104.
- electrons injected from the base layer 105 into the collector layer 104 become high energy, and are liable to transition to the upper valley due to phonon scattering.
- this bipolar transistor has a tendency that the carrier speed at the time of high voltage operation is lowered and the cutoff frequency is lowered.
- electrons are likely to be high energy in the collector layer 104, and GaN constituting the collector layer 104 has a relatively small band gap, so that avalanche breakdown is likely to occur. For this reason, this bipolar transistor has a problem that the collector breakdown voltage is low.
- An object of the present invention is to solve the above problems, to provide a bipolar transistor having a high collector breakdown voltage and excellent electron transport characteristics even at a high voltage.
- the bipolar transistor of the present invention includes a substrate, a collector layer, a p-type conductive base layer, and an n-type conductive emitter layer.
- the collector layer is formed over the substrate and includes a first nitride semiconductor.
- the p-type conductive base layer is formed on the collector layer and includes a second nitride semiconductor.
- the n-type conductive emitter layer is formed on the base layer and includes a third nitride semiconductor.
- the collector layer, the base layer, and the emitter layer are formed so that the crystal growth direction with respect to the substrate surface is parallel to the [0001] direction of the substrate.
- the first nitride semiconductor includes In yc Al xc Ga 1-xc-yc N (0 ⁇ xc ⁇ 1, 0 ⁇ yc ⁇ 1, 0 ⁇ xc + yc ⁇ 1).
- the a-axis length on the surface side in the first nitride semiconductor is longer than the a-axis length on the substrate side.
- a bipolar transistor having a high collector breakdown voltage and excellent electron transport characteristics even at a high voltage can be provided.
- FIG. 1 is a cross-sectional view showing a typical bipolar transistor configuration.
- FIG. 2 is an energy band diagram of the bipolar transistor shown in FIG.
- FIG. 3 is a sectional view showing the configuration of the bipolar transistor according to the first exemplary embodiment of the present invention.
- FIG. 4A is a graph showing typical examples of the Al composition distribution, the polarization amount distribution, and the charge distribution in the bipolar transistor according to the first exemplary embodiment of the present invention.
- FIG. 4B is a graph showing representative examples of the Al composition distribution, the polarization amount distribution, and the charge distribution in the bipolar transistor according to the first exemplary embodiment of the present invention.
- FIG. 4C is a graph showing representative examples of the Al composition distribution, the polarization amount distribution, and the charge distribution in the bipolar transistor according to the first exemplary embodiment of the present invention.
- FIG. 5 shows an example of an energy band diagram of the bipolar transistor according to the first exemplary embodiment of the present invention.
- FIG. 6 is a cross-sectional view showing the configuration of the bipolar transistor according to the second exemplary embodiment of the present invention.
- FIG. 7 shows an example of an energy band diagram of the bipolar transistor according to the second exemplary embodiment of the present invention.
- FIG. 8 is a cross-sectional view showing the configuration of the bipolar transistor according to the third exemplary embodiment of the present invention.
- FIG. 9 shows an example of an energy band diagram of the bipolar transistor according to the third exemplary embodiment of the present invention.
- FIG. 10 is a cross-sectional view showing the configuration of the bipolar transistor according to the fourth exemplary embodiment of the present invention.
- FIG. 11 shows an example of an energy band diagram of the bipolar transistor according to the fourth exemplary embodiment of the present invention.
- FIG. 12 is a cross-sectional view showing the configuration of the bipolar transistor according to the fifth exemplary embodiment of the present invention.
- FIG. 13 shows an example of an energy band diagram of the bipolar transistor according to the fifth exemplary embodiment of the present invention.
- FIG. 14 is a sectional view showing the structure of a bipolar transistor according to the sixth exemplary embodiment of the present invention.
- FIG. 15 shows an example of an energy band diagram of the bipolar transistor according to the sixth exemplary embodiment of the present invention.
- FIG. 16 is a cross-sectional view showing a configuration of a bipolar transistor according to the seventh exemplary embodiment of the present invention.
- FIG. 17A is a graph showing representative examples of the (Al, In) composition distribution, polarization amount distribution, and charge distribution in the bipolar transistor according to the seventh exemplary embodiment of the present invention.
- FIG. 17B is a graph showing representative examples of the (Al, In) composition distribution, polarization amount distribution, and charge distribution in the bipolar transistor according to the seventh exemplary embodiment of the present invention.
- FIG. 17C is a graph showing representative examples of (Al, In) composition distribution, polarization amount distribution, and charge distribution in the bipolar transistor according to the seventh exemplary embodiment of the present invention.
- FIG. 18 shows an example of an energy band diagram of the bipolar transistor according to the seventh exemplary embodiment of the present invention.
- FIG. 3 is a cross-sectional view showing the configuration of the bipolar transistor according to the first exemplary embodiment of the present invention.
- the bipolar transistor includes a substrate 10, a nucleation layer 11, a buffer layer 12, a subcollector layer 13, a collector layer 14, a base layer 15, an emitter layer 16, and a contact layer 17.
- the substrate 10 is a (0001) plane silicon carbide (SiC) substrate.
- the nucleation layer 11 is provided on the substrate 10 and is made of AlN.
- the buffer layer 12 is provided on the nucleation layer 11 and is made of undoped GaN.
- the subcollector layer 13 is provided on the buffer layer 12 and is made of high-concentration n-type GaN.
- the collector layer 14 is provided on the subcollector layer 13 and is made of undoped AlGaN.
- the base layer 15 is provided on the collector layer 14 and is made of p-type GaN.
- the emitter layer 16 is provided on the base layer 15 and is made of n-type AlGaN.
- the contact layer 17 is provided on the emitter layer 16 and is made of high-concentration n-type GaN.
- the emitter electrode 1E is provided in contact with the contact layer 17 (n-type GaN layer).
- the base electrode 1B is provided in contact with the base layer 15 (p-type GaN layer).
- the collector electrode 1C is provided in contact with the subcollector layer 13 (n-type GaN layer). Each electrode is in ohmic contact.
- This bipolar transistor is manufactured by the following manufacturing processes (A) and (B).
- MOCVD metal organic chemical vapor deposition
- A-1) Nucleation layer 11: undoped AlN, 200 nm.
- Buffer layer 12 undoped GaN, 1 ⁇ m.
- Subcollector layer 13 n-type GaN (Si: 3 ⁇ 10 18 cm ⁇ 3 ), 1 ⁇ m.
- Base layer 15 p-type GaN (Mg: 1 ⁇ 10 19 cm ⁇ 3 ), 100 nm.
- Emitter layer 16 n-type Al xe Ga 1-xe N (Si: 5 ⁇ 10 17 cm ⁇ 3 ), 500 nm.
- Contact layer 17 n-type GaN (Si: 1 ⁇ 10 19 cm ⁇ 3 ), 50 nm. These films have a crystal growth direction parallel to the [0001] direction of the substrate.
- the collector layer 14 which is an AlGaN layer has a graded composition structure or a stepped composition structure in which the Al composition xc is modulated in the film thickness direction.
- silicon is used as the n-type impurity.
- Magnesium (Mg) is used as the p-type impurity.
- beryllium (Be) may be used as the p-type impurity.
- the AlGaN layer as the collector layer 14 is undoped, it may be n-type with an impurity concentration of about 1 ⁇ 10 17 cm ⁇ 3 or less.
- a bipolar transistor is manufactured by patterning and forming each electrode in the order shown below with respect to the stacked structure formed in the step (A).
- a silicon dioxide (SiO 2 ) film is formed using a vapor phase deposition (chemical vapor deposition: hereinafter referred to as “CVD”) method.
- CVD chemical vapor deposition
- B-2 Subsequently, patterning of the emitter mesa region (formation of a pattern having an opening in the region where the base electrode is to be formed) is performed on the SiO 2 film.
- B-3 using the patterned SiO 2 film as a mask, for example, by reactive ion etching (hereinafter referred to as “RIE”) using a chlorine (Cl 2 ) -based gas,
- RIE reactive ion etching
- the base layer 15 which is a p-type GaN layer is exposed, and an external base region is formed.
- a metal such as palladium (Pd) / gold (Au) is deposited on the external base region.
- the base electrode 1B is formed by lifting off the SiO 2 film.
- a material of a p-type ohmic electrode you may use other materials, such as titanium (Ti) / Au.
- the crystal composition of the collector layer 14 (AlGaN layer) is selected so that the a-axis length on the surface side is longer than the a-axis length on the substrate side.
- the a-axis length is selected so as to increase from the subcollector layer 13 toward the base layer 15.
- the vertical axis shows the Al composition, polarization, and charge separately from the top.
- the horizontal axis indicates the position in the bipolar transistor (base layer 15 (GaN layer), collector layer 14 (AlGaN layer), sub-collector layer 13 (GaN layer)).
- FIG. 4A shows a case where the collector layer 14 (AlGaN layer) has a two-layer structure in which an Al xc1 Ga 1-xc1 N layer 141A and an Al xc2 Ga 1-xc2 N layer 141B are formed in this order.
- tensile strain is generated in the AlGaN layer (collector layer 14) on the GaN layer (subcollector layer 13), and negative polarization is generated in the AlGaN layer (collector layer 14).
- the sign of polarization is considered positive when the surface side is positively charged.
- the a-axis length increases from the subcollector layer 13 toward the base layer 15. Therefore, as shown in the middle graph, the piezo polarization changes in a direction to cancel (decrease) the negative polarization as it goes from the subcollector layer 13 to the base layer 15. At that time, as shown in the lower graph, space charges corresponding to the discontinuous amount of the polarization value are generated, so that positive charges are generated at the interface between the subcollector layer 13 (GaN layer) and the AlGaN layer 141A. Negative charges are generated at the interface between the AlGaN layer 141A and the AlGaN layer 141B and at the interface between the AlGaN layer 141B and the base layer 15 (GaN layer).
- a positive charge having a surface density of 1.1 ⁇ 10 13 cm ⁇ 2 is generated at the interface between the subcollector layer 13 (GaN layer) and the AlGaN layer 141A.
- Negative charges having a surface density of 5.4 ⁇ 10 12 cm ⁇ 2 are generated at the interface between the AlGaN layer 141A and the AlGaN layer 141B and at the interface between the AlGaN layer 141B and the base layer 15 (GaN layer), respectively.
- the collector layer 14 AlGaN layer
- Al xc1 Ga 1-xc1 N layer 142A Al xcb Ga 1-xcb N layer 142B
- Al xcc Ga 1-xcc N layer 142C Al xc2 Ga 1-xc2 N
- the a-axis length increases from the subcollector layer 13 toward the base layer 15.
- the piezo polarization changes in a direction to cancel (decrease) the negative polarization as it goes from the subcollector layer 13 to the base layer 15.
- space charges corresponding to the discontinuous amount of the polarization value are generated, so that positive charges are generated at the interface between the subcollector layer 13 (GaN layer) and the AlGaN layer 142A.
- the surface density of the surface of the subcollector layer 13 (GaN layer) and the AlGaN layer 142A is 1.1 ⁇ .
- a positive charge of 10 13 cm ⁇ 2 is generated.
- a negative charge having an areal density of 2.7 ⁇ 10 12 cm ⁇ 2 is generated.
- the collector layer 14 (AlGaN layer) is composed of a graded composition AlGaN layer 143, and the Al composition xc increases from xc1 to xc2 as it goes from the subcollector layer 13 (GaN layer) to the base layer 15 (GaN layer). This is the case when it is gradually decreased.
- the upper graph 0 ⁇ xc2 ⁇ xc1 ⁇ 1. This corresponds to the case where the number of steps is very large in the stepped composition structure of FIG. 4B.
- the interruption graph the polarization amount of the AlGaN layer 143 changes smoothly. Thereby, as shown in the lower graph, negative charges are continuously generated in the AlGaN layer 143.
- the surface density is 1.1 ⁇ 10 13 at the interface between the subcollector layer 13 (GaN layer) and the AlGaN layer 143.
- a positive charge of cm ⁇ 2 is generated.
- a negative charge having a volume density of 2.2 ⁇ 10 17 cm ⁇ 3 is generated inside the AlGaN layer 143.
- FIG. 5 shows an example of an energy band diagram of the bipolar transistor according to the first exemplary embodiment of the present invention.
- xe 0.1
- xc1 0.2
- xc2 0 in FIG. 4C
- a forward bias is applied between the base and emitter (base layer 15 and emitter layer 16), and the base and collector (base layer). This is the case where a reverse bias is applied between 15 and the collector layer 14).
- the “polarization charge” described in the upper part of the figure is the generation position of the polarization charge generated in the valence band (displayed at approximate positions in the subcollector layer 13, the collector layer 14, the base layer 15 and the emitter layer 16) and The relative amount (represented by the number of plus charges and the approximate number of minus charges) is schematically shown (the same applies to FIGS. 7, 9, 11, 13, 15, 18, and 2). .
- the band gap of the collector layer 14 (AlGaN layer) is larger on the subcollector layer 13 side.
- the position where the electric field intensity becomes maximum also moves to the subcollector layer 13 side. Therefore, the band gap at the position where the electric field is maximum is increased, and avalanche breakdown is unlikely to occur. For this reason, the collector breakdown voltage is also improved.
- the contact layer 17 of the n-type GaN layer is formed in contact with the emitter layer 16 of the n-type AlGaN layer.
- a gradient composition AlGaN layer may be inserted at the interface between the emitter layer 16 and the contact layer 17, and the Al composition may be smoothly reduced from the emitter layer 16 toward the contact layer 17. In this case, the barrier against electrons due to the conduction band offset of the heterojunction is reduced, and the emitter resistance is reduced.
- the base electrode 1B is formed in contact with the base layer 15 of the p-type GaN layer, the base electrode is formed via the p-type GaN layer or the p-type InGaN layer selectively regrown only in the external base region. May be. In this case, since the crystal damage of the external base layer by RIE used for forming the emitter mesa can be recovered by the annealing process, the base resistance is reduced.
- the insulating layer may be formed by increasing the resistance by ion implantation of nitrogen (N) or boron (B) into the collector layer 14 and the subcollector layer 13 below the external base region.
- the collector layer 14 and the subcollector layer 13 at the same location may be removed by etching. In these cases, the base-collector capacitance is reduced and the switching speed is improved.
- FIG. 6 is a cross-sectional view showing the configuration of the bipolar transistor according to the second exemplary embodiment of the present invention.
- the thickness of the collector layer 14 AlGaN layer
- the collector layer 14 cannot be made sufficiently thick, and the collector breakdown voltage is limited.
- such a limitation on the collector breakdown voltage can be removed.
- the bipolar transistor includes a substrate 10, a nucleation layer 11, a buffer layer 12, a subcollector layer 13, a collector layer 24, a base layer 15, an emitter layer 16, and a contact layer 17.
- the collector layer 14 is replaced with a collector layer 24 in the bipolar transistor of the first embodiment.
- the collector layer 24 has a two-layer structure in which an undoped GaN layer 24A and an undoped gradient composition Al xc Ga 1-xc N layer 24B are stacked in this order.
- the Al composition xc of the gradient composition Al xc Ga 1-xc N layer 24B is gradually reduced from xc1 to xc2 from the GaN layer 24A toward the base layer 15 (p-type GaN layer). However, 0 ⁇ xc2 ⁇ xc1 ⁇ 1.
- the state of the gradient composition Al xc Ga 1-xc N layer 24B is exemplified by the state of the collector layer 14 (AlGaN layer) in FIG. 4C.
- xc1 0.2
- xc2 0
- the layer thickness of the GaN layer 24A is 200 nm
- the layer thickness of the gradient composition Al xc Ga 1-xc N layer 24B is 500 nm.
- the film thickness of the gradient composition AlGaN layer 24B is equal to or less than the critical film thickness at which dislocation occurs.
- the manufacturing method of this bipolar transistor is the same as that of the first embodiment except that a part of the material of the film is different.
- the feature of this embodiment is that a GaN layer 24A is inserted between the sub-collector layer 13 of the n-type GaN layer and the gradient composition AlGaN layer 24B.
- the film thickness of the GaN layer 24A can be arbitrarily set without being limited by the critical film thickness. Therefore, the thickness of the collector layer 24 can be increased. For this reason, the collector breakdown voltage can be improved.
- FIG. 7 shows an example of an energy band diagram of the bipolar transistor according to the second exemplary embodiment of the present invention.
- the electric field strength inside the GaN layer 24A is uniform.
- negative charges are generated inside the gradient composition AlGaN layer 24B.
- an internal electric field is generated such that the potential for the electrons is convex upward. Therefore, electric field concentration at the base-collector (base layer 15-collector layer 24) interface is alleviated.
- the position at which the electric field intensity becomes maximum moves to the subcollector layer 13 side, so that electrons injected from the base layer 15 into the gradient composition AlGaN layer 24B of the collector layer 24 are unlikely to become high energy. For this reason, valley scattering is suppressed, the carrier velocity is improved, and the cutoff frequency is improved.
- the band gap of the gradient composition AlGaN layer 24B increases toward the subcollector layer 13 (GaN layer).
- the position where the electric field intensity becomes maximum also moves to the subcollector layer 13 side. Therefore, the band gap at the position where the electric field is maximum is increased, and avalanche breakdown is unlikely to occur. For this reason, the collector breakdown voltage is also improved.
- FIG. 8 is a cross-sectional view showing the configuration of the bipolar transistor according to the third exemplary embodiment of the present invention.
- the thickness of the collector layer 14 AlGaN layer
- the collector layer 14 cannot be made sufficiently thick, and the collector breakdown voltage is limited.
- such a limitation on the collector breakdown voltage can be removed.
- the bipolar transistor includes a substrate 10, a nucleation layer 11, a buffer layer 12, a subcollector layer 13, a collector layer 34, a base layer 15, an emitter layer 16, and a contact layer 17.
- the collector layer 14 is replaced with the collector layer 34 in the bipolar transistor of the first embodiment.
- the collector layer 34 has a two-layer structure in which an undoped gradient composition Al xc Ga 1-xc N layer 34A and an undoped GaN layer 34B are stacked in this order.
- the Al composition xc of the gradient composition Al xc Ga 1-xc N layer 34A is gradually decreased from xc1 to xc2 from the subcollector layer 13 (n-type GaN layer) toward the GaN layer 34B. However, 0 ⁇ xc2 ⁇ xc1 ⁇ 1.
- the state of the gradient composition Al xc Ga 1-xc N layer 34A is exemplified by the state of the collector layer 14 (AlGaN layer) in FIG. 4C, for example.
- the thickness of the graded composition AlGaN layer 34A is less than or equal to the critical thickness of dislocation generation.
- the manufacturing method of this bipolar transistor is the same as that of the first embodiment except that a part of the material of the film is different.
- the feature of this embodiment is that the GaN layer 34B is inserted between the gradient composition AlGaN layer 34A and the base layer 15 of the p-type GaN layer.
- the film thickness of the GaN layer 34B can be arbitrarily set without being limited by the critical film thickness. Therefore, the thickness of the collector layer 34 can be increased. For this reason, the collector breakdown voltage can be improved.
- FIG. 9 shows an example of an energy band diagram of the bipolar transistor according to the third exemplary embodiment of the present invention.
- the electric field strength inside the GaN layer 34B is uniform.
- negative charges are generated inside the gradient composition AlGaN layer 34A.
- an internal electric field is generated such that the potential for the electrons is convex upward. Therefore, electric field concentration at the base-collector (base layer 15-collector layer 34) interface is alleviated.
- the position at which the electric field strength becomes maximum moves to the subcollector layer 13 side, so that electrons injected from the base layer 15 into the GaN layer 34B of the collector layer 34 are unlikely to become high energy. For this reason, valley scattering is suppressed, the carrier velocity is improved, and the cutoff frequency is improved.
- the band gap of the gradient composition AlGaN layer 34A increases toward the subcollector layer 13 (GaN layer).
- the position where the electric field intensity becomes maximum also moves to the subcollector layer 13 side. Therefore, the band gap at the position where the electric field is maximum is increased, and avalanche breakdown is unlikely to occur. For this reason, the collector breakdown voltage is also improved.
- FIG. 10 is a cross-sectional view showing the configuration of the bipolar transistor according to the fourth exemplary embodiment of the present invention.
- the base side material and the collector side material at the base-collector (base layer-collector layer) interface are made of the same GaN. Therefore, there is a possibility that a so-called Kirk effect occurs in which holes in the base layer are diffused into the collector layer (AlGaN), the base length is substantially enlarged, and the switching speed is lowered. In the fourth embodiment, occurrence of such Kirk effect can be reliably prevented.
- the bipolar transistor includes a substrate 10, a nucleation layer 11, a buffer layer 12, a subcollector layer 13, a collector layer 44, a base layer 15, an emitter layer 16, and a contact layer 17.
- the collector layer 14 is replaced with the collector layer 44 in the bipolar transistor of the first embodiment.
- the collector layer 44 has a two-layer structure in which an undoped gradient composition Al xc Ga 1-xc N layer 44A and an undoped Al xc2 Ga 1-xc2 N layer 44B are stacked in this order.
- the Al composition xc of the gradient composition Al xc Ga 1-xc N layer 44A is gradually decreased from xc1 to xc2 from the subcollector layer 13 (n-type GaN layer) toward the AlGaN layer 44B. However, 0 ⁇ xc2 ⁇ xc1 ⁇ 1.
- the state of the gradient composition Al xc Ga 1-xc N layer 44A is exemplified by the state of the collector layer 14 (AlGaN layer) in FIG. 4C, for example.
- the layer thickness of the gradient composition Al xc Ga 1-xc N layer 44A is 250 nm
- the layer thickness of the Al xc2 Ga 1-xc2 N layer 44B is 500 nm.
- the layer thickness of the gradient composition Al xc Ga 1-xc N layer 44A and the film thickness of the Al xc2 Ga 1-xc2 N layer 44B are both less than or equal to the critical film thickness of dislocation generation.
- the manufacturing method of this bipolar transistor is the same as that of the first embodiment except that a part of the material of the film is different.
- the feature of the present embodiment is that an intermediate composition AlGaN layer 44B is inserted between the gradient composition AlGaN layer 44A and the base layer 15 of the p-type GaN layer.
- the AlGaN layer 44B has a larger band gap than the base layer 15 (p-type GaN layer). Therefore, the valence band offset functions as a potential barrier for holes. Therefore, diffusion of holes in the base layer 15 into the AlGaN layer 44B of the collector layer 44 is suppressed, and the Kirk effect is improved.
- FIG. 11 shows an example of an energy band diagram of the bipolar transistor according to the fourth exemplary embodiment of the present invention.
- the electric field strength inside the Al xc2 Ga 1-xc2 N layer 44B is uniform.
- negative charges are generated in the gradient composition Al xc Ga 1-xc N layer 44A.
- an internal electric field is generated such that the potential for the electrons is convex upward. Therefore, electric field concentration at the base-collector (base layer 15-collector layer 44) interface is alleviated.
- the position where the electric field intensity becomes maximum moves to the sub-collector layer 13 side, so that electrons injected from the base layer 15 into the Al xc2 Ga 1-xc2 N layer 44B of the collector layer 44 are less likely to become high energy. . For this reason, valley scattering is suppressed, the carrier velocity is improved, and the cutoff frequency is improved.
- the band gap of the AlGaN layer 44A becomes larger toward the subcollector layer 13 (GaN layer).
- the position where the electric field intensity becomes maximum also moves to the subcollector layer 13 side. Therefore, the band gap at the position where the electric field is maximum is increased, and avalanche breakdown is unlikely to occur. For this reason, the collector breakdown voltage is also improved.
- FIG. 12 is a cross-sectional view showing the configuration of the bipolar transistor according to the fifth exemplary embodiment of the present invention.
- the gradient composition AlGaN layer in which the Al composition is gradually changed is used as the collector layer.
- the reproducibility and uniformity of such element characteristics can be maintained at a high level.
- the bipolar transistor includes a substrate 10, a nucleation layer 11, a buffer layer 12, a subcollector layer 13, a collector layer 54, a base layer 15, an emitter layer 16, and a contact layer 17.
- the collector layer 14 is replaced with the collector layer 54 in the bipolar transistor of the first embodiment.
- the collector layer 54 has a two-layer structure in which a uniform composition undoped Al xc1 Ga 1-xc1 N layer 54A and a uniform composition undoped Al xc2 Ga 1-xc2 N layer 54B are laminated in this order.
- the Al composition xc1 of the Al xc1 Ga 1-xc1 N layer 54A is larger than the Al composition xc2 of the Al xc2 Ga 1-xc2 N layer 54B.
- the thickness of the Al 0.2 Ga 0.8 N layer 54A is 100 nm
- the thickness of the Al 0.1 Ga 0.9 N layer 54B is 500 nm.
- the film thickness of the AlGaN layer 54A and the film thickness of the AlGaN layer 54B are both less than or equal to the critical film thickness at which dislocation occurs.
- the manufacturing method of this bipolar transistor is the same as that of the first embodiment except that a part of the material of the film is different.
- a feature of the present embodiment is that the collector layer 55 is formed of an AlGaN layer having a stepped composition comprising an AlGaN layer 54A having a high Al composition and an AlGaN layer 54B having a low Al composition. Since the epitaxial growth is facilitated, the controllability of the crystal composition is improved, and the reproducibility and uniformity of device characteristics are improved.
- FIG. 13 shows an example of an energy band diagram of the bipolar transistor according to the fifth exemplary embodiment of the present invention.
- the band gap of the AlGaN layer 54A is larger than that of the AlGaN layer 54B.
- the electric field intensity is also maximum in the AlGaN layer 54A. Therefore, the band gap at the position where the electric field is maximum is increased, and avalanche breakdown is unlikely to occur. For this reason, the collector breakdown voltage is also improved.
- the AlGaN layer 54B has a larger band gap than the base layer 15. Therefore, the valence band offset functions as a potential barrier for holes. For this reason, diffusion of holes in the base layer 15 to the AlGaN layer 54B of the collector layer 54 is suppressed, and the Kirk effect is also improved.
- FIG. 14 is a sectional view showing the structure of a bipolar transistor according to the sixth exemplary embodiment of the present invention.
- the base-side material and the collector-side material at the base-collector (base layer-collector layer) interface are made of the same GaN. Therefore, it can be considered that the holes in the base layer 15 diffuse into the collector layer 34, the base length is substantially enlarged, and the so-called Kirk effect is generated in which the switching speed is lowered. In the sixth embodiment, it is possible to reliably prevent such Kirk effect.
- the bipolar transistor includes a substrate 10, a nucleation layer 11, a buffer layer 12, a subcollector layer 13, a collector layer 64, a base layer 65, an emitter layer 16, and a contact layer 17.
- the collector layer 14 is replaced with the collector layer 64 and the base layer 15 is replaced with the base layer 65 in the bipolar transistor of the first embodiment.
- the collector layer 64 has a two-layer structure in which an undoped gradient composition Al xc Ga 1-xc N layer 64A and an undoped Al xc2 Ga 1-xc2 N layer 64B are stacked in this order.
- the base layer 65 is composed of a p-type In yb Ga 1-yb N layer.
- the Al composition xc of the gradient composition Al xc Ga 1-xc N layer 64A is gradually decreased from xc1 to xc2 as it goes from the subcollector layer 13 (n-type GaN layer) to the AlGaN layer 64B. However, 0 ⁇ xc2 ⁇ xc1 ⁇ 1.
- the state of the gradient composition Al xc Ga 1-xc N layer 64A is exemplified by the state of the collector layer 14 (AlGaN layer) in FIG. 4C, for example.
- the layer thickness of the gradient composition Al xc Ga 1-xc N layer 64A is 500 nm
- the layer thickness of the Al xc2 Ga 1-xc2 N layer 64B (GaN layer) is 500 nm.
- the thickness of the gradient composition AlGaN layer 64A is equal to or less than the critical thickness of dislocation generation.
- the manufacturing method of this bipolar transistor is the same as that of the first embodiment except that a part of the material of the film is different.
- the base layer 65 is formed of an InGaN layer having a band gap smaller than that of the GaN layer
- the collector layer 64 is formed of a gradient composition AlGaN layer 64A and an AlGaN layer 64B.
- FIG. 15 shows an example of an energy band diagram of the bipolar transistor according to the sixth exemplary embodiment of the present invention.
- the forward bias is applied when a reverse bias is applied between the base and collector (base layer 65 and collector layer 64).
- the electric field strength inside the GaN layer 64B is uniform.
- negative charges are generated inside the gradient composition Al xc Ga 1-xc N layer 64A.
- an internal electric field is generated such that the potential for the electrons is convex upward. Therefore, electric field concentration at the base-collector (base layer 65-collector layer 64) interface is alleviated.
- the position at which the electric field intensity becomes maximum moves to the sub-collector layer 13 side, so that electrons injected from the base layer 65 to the GaN layer 64B of the collector layer 64 are unlikely to become high energy. For this reason, valley scattering is suppressed, the carrier velocity is improved, and the cutoff frequency is improved.
- the band gap of the AlGaN layer 64A increases toward the subcollector layer 13 (GaN layer).
- the position where the electric field intensity becomes maximum also moves to the subcollector layer 13 side. Therefore, the band gap at the position where the electric field is maximum is increased, and avalanche breakdown is unlikely to occur. For this reason, the collector breakdown voltage is also improved.
- FIG. 16 is a cross-sectional view showing a configuration of a bipolar transistor according to the seventh exemplary embodiment of the present invention.
- the Al composition ratio of the AlGaN layer in the collector layer is decreased as it goes from the subcollector layer to the base layer.
- the a-axis length of AlGaN increases as the Al composition decreases, negative charges are generated in the AlGaN layer.
- the a-axis length of the InAlGaN layer increases as the In composition increases.
- the collector layer is composed of an InAlGaN layer and the In composition is increased from the subcollector layer toward the base layer.
- the collector layer may be composed of an InAlGaN layer, and the Al composition may be decreased from the subcollector layer toward the base layer.
- the collector layer is composed of the InAlGaN layer.
- the bipolar transistor includes a substrate 10, a nucleation layer 11, a buffer layer 12, a subcollector layer 13, a collector layer 74, a base layer 75, an emitter layer 16, and a contact layer 17.
- the collector layer 14 is replaced with the collector layer 74 and the base layer 15 is replaced with the base layer 75 in the bipolar transistor of the first embodiment.
- the collector layer 74 is composed of an undoped In yc Al xc Ga 1-xc-yc N layer
- the base layer 75 is composed of a p-type In yb Ga 1-yb N layer.
- the collector layer 74 (InAlGaN layer) has a gradient composition structure or a stepped composition structure in which the Al composition xc or the In composition yc is modulated in the film thickness direction.
- the Al composition at the interface with the subcollector layer 13 n-type GaN layer
- xc xc1
- the Al composition at the interface with the base layer 75 p-type InGaN layer
- the Al composition xc of the collector layer 74 decreases or becomes constant as it goes from the subcollector layer 13 to the base layer 75. Further, the In composition yc increases or becomes constant as it goes from the subcollector layer 13 to the base layer 75.
- the collector layer 74 is thinner than the critical film thickness at which dislocation occurs, and is a strained lattice layer.
- the average Al composition of the collector layer 74 (InAlGaN layer) is ⁇ xc>, and the average In composition is ⁇ yc>.
- the In composition yb of the base layer 75 is 0 ⁇ yb ⁇ 1. From the viewpoint of suppressing the occurrence of dislocation and obtaining good crystal quality, it is more preferable to satisfy 0 ⁇ yb ⁇ 0.1.
- the manufacturing method of this bipolar transistor is the same as that of the first embodiment except that a part of the material of the film is different.
- FIGS. 17A to 17C are graphs showing representative examples of the (Al, In) composition distribution, polarization amount distribution, and charge distribution in the bipolar transistor according to the seventh exemplary embodiment of the present invention.
- the crystal composition of the collector layer 74 (InAlGaN layer) is selected so that the a-axis length increases from the subcollector layer 13 toward the base layer 75.
- the vertical axis shows the In composition, Al composition, polarization, and charge separately from the top. However, the downward direction of the Al composition is positive.
- the horizontal axis indicates the position (base layer 75 (InGaN layer), collector layer 74 (InAlGaN layer), subcollector layer 13 (GaN layer)) in the bipolar transistor.
- the collector layer 74 (In yc Al xc Ga 1-xc-yc N layer) is formed of an InAlGaN layer 741 having a composition gradient that satisfies 0 ⁇ xc2 ⁇ xc1 ⁇ 1 and 0 ⁇ yc1 ⁇ yc2 ⁇ 1. This is the case.
- the Al composition of the InAlGaN layer 741 decreases and the In composition increases from the subcollector layer 13 toward the base layer 75.
- the polarization decreases as the subcollector layer 13 moves toward the base layer 15 as shown in the middle graph. It changes in the direction to make.
- the polarization amount changes in the film thickness direction.
- positive charges are generated at the interface between the subcollector layer 13 (GaN layer) and the InAlGaN layer 741.
- a negative charge is generated inside the InAlGaN layer 741.
- the In composition increases from the subcollector layer 13 toward the base layer 75 while the Al composition of the InAlGaN layer 742 remains constant.
- the a-axis length increases from the subcollector layer 13 toward the base layer 75, the amount of polarization changes in the film thickness direction as shown in the middle graph.
- the Al composition decreases from the subcollector layer 13 toward the base layer 75 while the In composition of the InAlGaN layer 743 remains constant.
- the a-axis length increases from the subcollector layer 13 toward the base layer 75, the amount of polarization changes in the film thickness direction as shown in the middle graph. Therefore, in the case of (0001) plane growth, negative charges are generated inside the InAlGaN layer 743.
- FIG. 18 shows an example of an energy band diagram of the bipolar transistor according to the seventh exemplary embodiment of the present invention. This energy band diagram is obtained when a forward bias is applied between the base-emitter (base layer 75-emitter layer 16) and a reverse bias is applied between the base-collector (base layer 75-collector layer 74) in FIG. 17B. is there.
- Each film thickness of the base layer 75 (InGaN layer) and the collector layer 74 (InAlGaN layer) is set to be equal to or less than the critical film thickness of dislocation generation.
- the InGaN layer of the base layer 75 may be 100 nm
- the gradient composition InAlGaN layer of the collector layer 74 may be 500 nm.
- An internal electric field is generated in the collector layer 74 (InAlGaN layer) so that the potential for electrons is convex upward. Therefore, electric field concentration at the base-collector (base layer 75-collector layer 74) interface is alleviated.
- the position where the electric field intensity is maximum moves to the sub-collector layer 13 side, so that electrons injected from the base layer 75 into the collector layer 74 are unlikely to become high energy. For this reason, valley scattering is suppressed, the carrier velocity is improved, and the cutoff frequency is improved.
- the band gap of the collector layer 74 becomes larger toward the subcollector layer 13.
- the position where the electric field intensity becomes maximum also moves to the subcollector layer 13 side. Therefore, the band gap at the position where the electric field is maximum is increased, and avalanche breakdown is unlikely to occur. For this reason, the collector breakdown voltage is also improved.
- the collector layer 74 is composed of an InAlGaN layer.
- SiC is used as the substrate, but other substrates such as silicon (Si), sapphire (Al 2 O 3 ), and gallium nitride (GaN) may be used.
- Si silicon
- Al 2 O 3 aluminum oxide
- GaN gallium nitride
- AlGaN is used as the material of the emitter layer
- other group III nitride semiconductors having a band gap smaller than that of the base layer may be used.
- AlN, InAlN, or InAlGaN may be used.
- GaN or InGaN is used as the material for the base layer
- other group III nitride semiconductors having a band gap that is not larger than that of the collector layer may be used.
- InN, AlGaN, InAlN, or InAlGaN may be used.
- GaN is used as the material for the contact layer and the subcollector layer, other group III nitride semiconductors may be used.
- InN, InGaN, InAlN, AlGaN, or InAlGaN may be used.
- the present invention has been described by taking the emitter-up structure bipolar transistor as an example.
- the main point of the present invention is that the crystal growth direction with respect to the substrate surface is parallel to the [0001] direction and the collector is made of (In) AlGaN having a compositional modulation in which the a-axis length increases from the substrate toward the surface.
- the layer By forming the layer, negative fixed charges are generated. Even if the positional relationship between the base layer and the emitter layer is reversed, a negative charge is generated in the collector layer, so that the same effect can be obtained.
- the collector is composed of (In) AlGaN having a compositional modulation such that the a-axis length increases from the substrate toward the surface.
- a layer may be formed.
- the bipolar transistor of the present invention has the composition formula In yc Al xc Ga 1-xc-yc N (0 ⁇ 0) formed so that the crystal growth direction with respect to the substrate surface is parallel to the [0001] direction.
- xc ⁇ 1, 0 ⁇ yc ⁇ 1, 0 ⁇ xc + yc ⁇ 1) a collector layer made of a first nitride semiconductor, a p-type conductive base layer made of a second nitride semiconductor, It has an n-type conductive emitter layer made of a nitride semiconductor.
- the a-axis length of the first nitride semiconductor is formed to increase from the substrate toward the surface in at least a part of the collector layer. Due to the polarization effect, negative charges are generated inside the InAlGaN layer, so that the electric field concentration at the base-collector interface is alleviated. Since electrons injected from the base layer into the collector layer are unlikely to become high energy, valley scattering is suppressed, carrier velocity is improved, and cutoff frequency is improved. In addition, since the band gap at the position where the electric field intensity is maximum is large, avalanche breakdown hardly occurs and the collector breakdown voltage is improved. For this reason, it greatly contributes to higher breakdown voltage and higher speed of the bipolar transistor.
Abstract
Description
本発明の第1の実施の形態に係るバイポーラトランジスタの構成について説明する。図3は、本発明の第1の実施の形態に係るバイポーラトランジスタの構成を示す断面図である。図に示されるように、バイポーラトランジスタは、基板10と、核生成層11と、バッファ層12と、サブコレクタ層13と、コレクタ層14と、ベース層15と、エミッタ層16と、コンタクト層17と、エミッタ電極1Eと、ベース電極1Bと、コレクタ電極1Cとを具備する。
これらの膜は、結晶成長方向が、基板の[0001]方向に平行になる。
このようにして、図3に示されるようなバイポーラトランジスタが製造される。
本発明の第2の実施の形態に係るバイポーラトランジスタの構成について説明する。図6は、本発明の第2の実施の形態に係るバイポーラトランジスタの構成を示す断面図である。第1の実施の形態では、コレクタ層14(AlGaN層)の厚さを転位発生の臨界膜厚で制限している。そのため、コレクタ層14を十分には厚く出来ず、コレクタ耐圧が制限されている。第2の実施の形態では、このようなコレクタ耐圧の制限を除くことができる。
本発明の第3の実施の形態に係るバイポーラトランジスタの構成について説明する。図8は、本発明の第3の実施の形態に係るバイポーラトランジスタの構成を示す断面図である。第1の実施の形態では、コレクタ層14(AlGaN層)の厚さを転位発生の臨界膜厚で制限している。そのため、コレクタ層14を十分には厚く出来ず、コレクタ耐圧が制限されている。第3の実施の形態では、このようなコレクタ耐圧の制限を除くことができる。
本発明の第4の実施の形態に係るバイポーラトランジスタの構成について説明する。図10は、本発明の第4の実施の形態に係るバイポーラトランジスタの構成を示す断面図である。上記の実施の形態では、ベース-コレクタ(ベース層-コレクタ層)界面におけるベース側の材料とコレクタ側の材料とが同一のGaNで構成されている。そのため、ベース層内の正孔がコレクタ層(AlGaN)に拡散して実質的にベース長が拡大して、スイッチング速度が低下する、所謂、カーク(Kirk)効果が発生する可能性が考え得る。第4の実施の形態では、このようなカーク(Kirk)効果の発生を確実に防止することができる。
本発明の第5の実施の形態に係るバイポーラトランジスタの構成について説明する。図12は、本発明の第5の実施の形態に係るバイポーラトランジスタの構成を示す断面図である。上記の実施の形態では、コレクタ層としてAl組成を徐々に変化させた傾斜組成AlGaN層を用いていた。このようなエピタキシャル結晶層を作製するためには、原料ガス流量を時間と共に変化させる必要があり、結晶組成の制御性に困難が伴う。このため、素子特性の再現性や均一性を高度に維持することが容易ではない。第5の実施の形態では、このような素子特性の再現性や均一性を高度に維持することができる。
本発明の第6の実施の形態に係るバイポーラトランジスタの構成について説明する。図14は、本発明の第6の実施の形態に係るバイポーラトランジスタの構成を示す断面図である。例えば、第1~第3の実施の形態では、ベース-コレクタ(ベース層-コレクタ層)界面におけるベース側の材料とコレクタ側の材料とが同一のGaNで構成されている。そのため、ベース層15内の正孔がコレクタ層34に拡散して実質的にベース長が拡大して、スイッチング速度が低下する、所謂、カーク(Kirk)効果が発生する可能性が考え得る。第6の実施の形態では、このようなカーク(Kirk)効果の発生を確実に防止することができる。
本発明の第7の実施の形態に係るバイポーラトランジスタの構成について説明する。図16は、本発明の第7の実施の形態に係るバイポーラトランジスタの構成を示す断面図である。上記の実施の形態では、(0001)面成長において、サブコレクタ層からベース層へ向かうにしたがってコレクタ層内のAlGaN層のAl組成比を減少させている。このとき、Al組成の減少と共にAlGaNのa軸長は増加するため、AlGaN層内に負の電荷が発生する。同様に、InAlGaN層のa軸長はIn組成の増加と共に増加する。このため、コレクタ層をInAlGaN層によって構成し、サブコレクタ層からベース層へ向かうにしたがってIn組成を増加させても同様な効果を得ることが可能である。あるいは、コレクタ層をInAlGaN層によって構成し、サブコレクタ層からベース層へ向かうにしたがってAl組成を減少させても良い。このように、第7の実施の形態では、コレクタ層をInAlGaN層によって構成している。
<xc>=4.6<yc>・・・(式1)となる。このことから、転位発生を抑制し、良好な結晶品質を得るためには、
|<xc>-4.6<yc>|<0.5・・・(式2)を充たすようにすればよい。
Claims (11)
- 基板と、
前記基板の上方に形成され、第一の窒化物半導体を含むコレクタ層と、
前記コレクタ層上に形成され、第二の窒化物半導体を含むp型導電性のベース層と、
前記ベース層上に形成され、第三の窒化物半導体を含むn型導電性のエミッタ層と
を具備し、
前記コレクタ層、前記ベース層、及び前記エミッタ層は、前記基板面に対する結晶成長方向が前記基板の[0001]方向に平行となるように形成され、
前記第一の窒化物半導体は、InycAlxcGa1-xc-ycN(0≦xc≦1、0≦yc≦1、0<xc+yc≦1)を含み、
前記第一の窒化物半導体における表面側のa軸長は、前記基板側のa軸長よりも長い
バイポーラトランジスタ。 - 請求の範囲1に記載のバイポーラトランジスタであって、
前前記第一の窒化物半導体のa軸長が前記基板側から表面側に向かって増加するように形成されている
バイポーラトランジスタ。 - 請求の範囲2に記載のバイポーラトランジスタであって、
前記第一の窒化物半導体のAl組成xcが前記基板側から表面側に向かって減少するように形成されている
バイポーラトランジスタ。 - 請求の範囲3に記載のバイポーラトランジスタであって、
前記第一の窒化物半導体の平均Al組成を<xc>、平均In組成を<yc>としたとき、前記第一の窒化物半導体は、以下の式を満たす
|<xc>-4.6<yc>|<0.5
バイポーラトランジスタ。 - 請求の範囲3に記載のバイポーラトランジスタであって、
前記コレクタ層は、前記第一の窒化物半導体に接して設けられた第四の窒化物半導体を更に含み
前記第四の窒化物半導体は、Alxc2Ga1-xc2N(0≦xc2<xc≦1)を含む
バイポーラトランジスタ。 - 請求の範囲5に記載のバイポーラトランジスタであって、
前記ベース層は、InybGa1-ybN(0≦yb≦1)を含む
バイポーラトランジスタ。 - 請求の範囲2に記載のバイポーラトランジスタであって、
前記第一の窒化物半導体のIn組成ycが前記基板側から表面側に向かって増加するように形成されている
バイポーラトランジスタ。 - 請求の範囲7に記載のバイポーラトランジスタであって、
前記第一の窒化物半導体の平均Al組成を<xc>、平均In組成を<yc>としたとき、前記第一の窒化物半導体は、以下の式を満たす
|<xc>-4.6<yc>|<0.5
バイポーラトランジスタ。 - 請求の範囲1乃至8のいずれか一項に記載のバイポーラトランジスタであって、
前記基板上に、前記コレクタ層、前記ベース層、前記エミッタ層の順に形成されている
バイポーラトランジスタ。 - 請求の範囲1乃至8のいずれか一項に記載のバイポーラトランジスタであって、
前記ベース層と前記コレクタ層との界面において前記第一の窒化物半導体のバンドギャップが前記第二の窒化物半導体のバンドギャップより大きくなるように形成されている
バイポーラトランジスタ。 - 請求の範囲1乃至8のいずれか一項に記載のバイポーラトランジスタであって、
前記コレクタ層に接して形成されたn型伝導性のサブコレクタ層と、
前記エミッタ層と電気的に接続された第一のオーミック電極と、
前記ベース層と電気的に接続された第二のオーミック電極と、
前記サブコレクタ層と電気的に接続された第三のオーミック電極と
を更に具備する
バイポーラトランジスタ。
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2010534789A JP5628680B2 (ja) | 2008-10-21 | 2009-10-16 | バイポーラトランジスタ |
CN200980150271.2A CN102246283B (zh) | 2008-10-21 | 2009-10-16 | 双极晶体管 |
US13/124,872 US8395237B2 (en) | 2008-10-21 | 2009-10-16 | Group nitride bipolar transistor |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2008-270883 | 2008-10-21 | ||
JP2008270883 | 2008-10-21 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2010047280A1 true WO2010047280A1 (ja) | 2010-04-29 |
Family
ID=42119321
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2009/067907 WO2010047280A1 (ja) | 2008-10-21 | 2009-10-16 | バイポーラトランジスタ |
Country Status (4)
Country | Link |
---|---|
US (1) | US8395237B2 (ja) |
JP (1) | JP5628680B2 (ja) |
CN (1) | CN102246283B (ja) |
WO (1) | WO2010047280A1 (ja) |
Families Citing this family (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2010047281A1 (ja) * | 2008-10-21 | 2010-04-29 | 日本電気株式会社 | バイポーラトランジスタ |
CN107169160B (zh) * | 2017-04-12 | 2020-10-20 | 西安电子科技大学 | 一种异质结双极晶体管非电离能量损失的计算方法 |
CN110310989A (zh) * | 2019-07-23 | 2019-10-08 | 上海科技大学 | 一种双异质结单极性晶体管的器件结构 |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007188991A (ja) * | 2006-01-12 | 2007-07-26 | Nippon Telegr & Teleph Corp <Ntt> | バイポーラトランジスタ |
Family Cites Families (30)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2906407B2 (ja) | 1987-11-18 | 1999-06-21 | 株式会社日立製作所 | 半導体装置 |
JP2576165B2 (ja) | 1987-11-30 | 1997-01-29 | 日本電気株式会社 | バイポーラトランジスタの製造方法 |
FR2692721B1 (fr) * | 1992-06-17 | 1995-06-30 | France Telecom | Procede de realisation de transistor bipolaire a heterojonction et transistor obtenu. |
JP3117831B2 (ja) * | 1993-02-17 | 2000-12-18 | シャープ株式会社 | 半導体装置 |
US5689122A (en) * | 1995-08-14 | 1997-11-18 | Lucent Technologies Inc. | InP/InGaAs monolithic integrated demultiplexer, photodetector, and heterojunction bipolar transistor |
JP3310514B2 (ja) * | 1995-12-22 | 2002-08-05 | シャープ株式会社 | 半導体装置 |
JP3366919B2 (ja) * | 1997-06-27 | 2003-01-14 | エヌイーシー化合物デバイス株式会社 | 半導体装置 |
JP3392788B2 (ja) * | 1999-08-19 | 2003-03-31 | シャープ株式会社 | 半導体装置 |
FR2803102B1 (fr) | 1999-12-23 | 2002-03-22 | Thomson Csf | Transistor bipolaire a heterojonction a collecteur en haut et procede de realisation |
US6596079B1 (en) * | 2000-03-13 | 2003-07-22 | Advanced Technology Materials, Inc. | III-V nitride substrate boule and method of making and using the same |
JP2001308103A (ja) * | 2000-04-19 | 2001-11-02 | Sharp Corp | ヘテロ接合バイポーラトランジスタおよびその製造方法 |
US6849874B2 (en) * | 2001-10-26 | 2005-02-01 | Cree, Inc. | Minimizing degradation of SiC bipolar semiconductor devices |
JP3573737B2 (ja) * | 2002-01-18 | 2004-10-06 | Nec化合物デバイス株式会社 | ヘテロ接合バイポーラ・トランジスタおよび半導体集積回路 |
JP4159828B2 (ja) * | 2002-08-26 | 2008-10-01 | 独立行政法人物質・材料研究機構 | 二硼化物単結晶基板、それを用いた半導体レーザダイオード及び半導体装置並びにそれらの製造方法 |
JP2004140339A (ja) | 2002-09-25 | 2004-05-13 | Univ Chiba | 窒化物系ヘテロ構造を有するデバイス及びその製造方法 |
US6806513B2 (en) * | 2002-10-08 | 2004-10-19 | Eic Corporation | Heterojunction bipolar transistor having wide bandgap material in collector |
CN1698210A (zh) | 2003-01-06 | 2005-11-16 | 日本电信电话株式会社 | P型氮化物半导体结构以及双极晶体管 |
US7781356B2 (en) * | 2003-02-12 | 2010-08-24 | Arizona Board of Regents, a Body Corporate | Epitaxial growth of group III nitrides on silicon substrates via a reflective lattice-matched zirconium diboride buffer layer |
US20050221515A1 (en) * | 2004-03-30 | 2005-10-06 | Katsunori Yanashima | Method for producing semiconductor light emitting device, method for producing semiconductor device, method for producing device, method for growing nitride type III-V group compound semiconductor layer, method for growing semiconductor layer, and method for growing layer |
JP4955384B2 (ja) * | 2004-03-30 | 2012-06-20 | 日本電気株式会社 | 半導体装置 |
CA2529595C (en) * | 2004-07-01 | 2013-02-26 | Nippon Telegraph And Telephone Corporation | Heterostructure bipolar transistor |
CN100463121C (zh) * | 2004-07-01 | 2009-02-18 | 日本电信电话株式会社 | 异质结构双极型晶体管 |
US7339255B2 (en) * | 2004-08-24 | 2008-03-04 | Kabushiki Kaisha Toshiba | Semiconductor device having bidirectionally inclined toward <1-100> and <11-20> relative to {0001} crystal planes |
JP2006128554A (ja) | 2004-11-01 | 2006-05-18 | Matsushita Electric Ind Co Ltd | バイポーラトランジスタおよびその製造方法 |
JP4789489B2 (ja) | 2005-03-11 | 2011-10-12 | アンリツ株式会社 | マイクロ波モノリシック集積回路 |
JP4777699B2 (ja) * | 2005-06-13 | 2011-09-21 | 本田技研工業株式会社 | バイポーラ型半導体装置およびその製造方法 |
JP2008004779A (ja) | 2006-06-23 | 2008-01-10 | Matsushita Electric Ind Co Ltd | 窒化物半導体バイポーラトランジスタ及び窒化物半導体バイポーラトランジスタの製造方法 |
US7569910B2 (en) * | 2006-08-30 | 2009-08-04 | Silicon Storage Technology, Inc. | Multiple-transistor structure systems and methods in which portions of a first transistor and a second transistor are formed from the same layer |
GB2447921B (en) * | 2007-03-28 | 2012-01-25 | Rfmd Uk Ltd | A Transistor |
US20090065811A1 (en) * | 2007-09-07 | 2009-03-12 | Ping-Chih Chang | Semiconductor Device with OHMIC Contact and Method of Making the Same |
-
2009
- 2009-10-16 WO PCT/JP2009/067907 patent/WO2010047280A1/ja active Application Filing
- 2009-10-16 US US13/124,872 patent/US8395237B2/en not_active Expired - Fee Related
- 2009-10-16 JP JP2010534789A patent/JP5628680B2/ja not_active Expired - Fee Related
- 2009-10-16 CN CN200980150271.2A patent/CN102246283B/zh not_active Expired - Fee Related
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2007188991A (ja) * | 2006-01-12 | 2007-07-26 | Nippon Telegr & Teleph Corp <Ntt> | バイポーラトランジスタ |
Also Published As
Publication number | Publication date |
---|---|
JPWO2010047280A1 (ja) | 2012-03-22 |
CN102246283A (zh) | 2011-11-16 |
US20110241075A1 (en) | 2011-10-06 |
US8395237B2 (en) | 2013-03-12 |
JP5628680B2 (ja) | 2014-11-19 |
CN102246283B (zh) | 2014-08-06 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP5628681B2 (ja) | バイポーラトランジスタ | |
JP4179539B2 (ja) | 化合物半導体装置及びその製造方法 | |
JP4663156B2 (ja) | 化合物半導体装置 | |
JP3751791B2 (ja) | ヘテロ接合電界効果トランジスタ | |
JP4531071B2 (ja) | 化合物半導体装置 | |
JP2013235873A (ja) | 半導体装置およびその製造方法 | |
JP2011166067A (ja) | 窒化物半導体装置 | |
JP2006261642A (ja) | 電界効果トランジスタおよびその製造方法 | |
JPWO2009081584A1 (ja) | 半導体装置 | |
JP2010171416A (ja) | 半導体装置、半導体装置の製造方法および半導体装置のリーク電流低減方法 | |
US20070232008A1 (en) | Semiconductor device and hetero-junction bipolar transistor | |
JP2010199597A (ja) | 化合物半導体装置の製造方法 | |
JP2008016615A (ja) | バイポーラトランジスタ | |
JP6242678B2 (ja) | 窒化物半導体素子及びその製造方法 | |
JP5628680B2 (ja) | バイポーラトランジスタ | |
JP4038814B2 (ja) | 半導体装置および電界効果トランジスタ | |
WO2020240725A1 (ja) | ヘテロ接合バイポーラトランジスタおよびその作製方法 | |
JP3853341B2 (ja) | バイポーラトランジスタ | |
JP5418482B2 (ja) | 化合物半導体積層構造 | |
CN212182338U (zh) | 半导体结构 | |
JP5730505B2 (ja) | 化合物半導体装置 | |
JP5387686B2 (ja) | 窒化物半導体装置および電子装置 | |
WO2021229702A1 (ja) | 半導体装置 | |
JP5701805B2 (ja) | 窒化物半導体ショットキダイオードの製造方法 | |
JP5368397B2 (ja) | 電界効果トランジスタおよびその製造方法 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
WWE | Wipo information: entry into national phase |
Ref document number: 200980150271.2 Country of ref document: CN |
|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 09821977 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2010534789 Country of ref document: JP Kind code of ref document: A |
|
NENP | Non-entry into the national phase |
Ref country code: DE |
|
WWE | Wipo information: entry into national phase |
Ref document number: 13124872 Country of ref document: US |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 09821977 Country of ref document: EP Kind code of ref document: A1 |