CN1111313C - Bipolar heterojunction transistor - Google Patents
Bipolar heterojunction transistor Download PDFInfo
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- CN1111313C CN1111313C CN 99109641 CN99109641A CN1111313C CN 1111313 C CN1111313 C CN 1111313C CN 99109641 CN99109641 CN 99109641 CN 99109641 A CN99109641 A CN 99109641A CN 1111313 C CN1111313 C CN 1111313C
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- quantum well
- doping
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- 229910000577 Silicon-germanium Inorganic materials 0.000 claims description 16
- 230000004888 barrier function Effects 0.000 claims description 14
- 239000000463 material Substances 0.000 claims description 3
- 230000015572 biosynthetic process Effects 0.000 claims description 2
- 239000000969 carrier Substances 0.000 abstract 3
- 230000007704 transition Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 9
- 238000010276 construction Methods 0.000 description 7
- 230000008859 change Effects 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 230000032258 transport Effects 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 230000005611 electricity Effects 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 239000012141 concentrate Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 230000010355 oscillation Effects 0.000 description 2
- 229910000980 Aluminium gallium arsenide Inorganic materials 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000002800 charge carrier Substances 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000011982 device technology Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000004377 microelectronic Methods 0.000 description 1
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Abstract
The present invention relates to a heterojunction bipolar transistor in a quantum well base region, which belongs to the technical field of high-speed micro electrons. The present invention is characterized in that one or a plurality of undoped quantum well layers are longitudinally grown along the base region, majority carriers in the base region mainly transport in the quantum well transversely, and therefore, the transverse mobility of the majority carrier is greatly increased. A longitudinal drift field of minority carriers is simultaneously formed, and the longitudinal transition of the minority carriers is accelerated. On the basis of not increasing the width of the base region and doping total amount, base resistance rb is obviously reduced, and therefore, the heterojunction bipolar transistor with high current gains, high fT, high fmax and low noise coefficients NF is obtained.
Description
Technical field
The present invention relates to a kind of heterojunction bipolar transistor, particularly relate to a kind of heterojunction bipolar transistor, belong to the high speed microelectronics technology with quantum well base structure.
Background technology
As the ultrahigh speed transistor, gain, frequency parameter f
T, f
MaxWith noise factor N
FIt is crucial technical indicator.Because advanced material growth facility and meticulous technology are arranged, the horizontal and vertical size of device is all very little, thereby these indexs have reached very high level respectively in the world.But because the longitudinal size of device base has dropped to about 300-500 , the contradiction of the mutual restriction between these parameters becomes increasingly conspicuous.For improving f
TMust reduce the base longitudinal size, so the lateral resistance r of base as far as possible
bWill improve and make f
MaxReduce, noise increases.For improving f
Max, reduce r
bMust be in base heavy doping, but base heavy doping makes the gain variation conversely again, and scattering increases, the electronics vertical and horizontal transport and are obstructed and reduce f
T, the also difficult f that improves
MaxAnd reduction noise.Thereby can only trade off by between usually, or to sacrifice f
MaxWith noise be that cost obtains high f
TThe gain characteristic of becoming reconciled, or to sacrifice f
TObtain high f with gain for cost
MaxAnd low noise.With SiGe/Si type heterojunction bipolar transistor is example, and the method for handling above problem at present in the world mainly contains two kinds of schemes:
(1) adopts emitter-base bandgap grading doping content occurred frequently, gradual change Ge component base (distribution triangular in shape of Ge component) and gradual change base doping structure (see figure 1).This method easily obtains higher f
T, but because base doping is lower, so the big f of base resistance
MaxBe worth lowlyer, noise is bigger.
(2) adopt narrow base, high base doping, mix in low emitter region, evenly Ge component base.This method easily obtains higher f
MaxAnd lower base resistance, but because the very high doping in base, the gain characteristic variation is suffered very strong scattering when electronics is vertically getted in the base, the base lacks stronger drift field, so f
TThe low (see figure 2) of value.
Summary of the invention
The objective of the invention is to overcome the defective of above-mentioned prior art, a kind of novel heterojunction bipolar transistor structure is provided, and it can improve high-frequency gain effectively on the basis of not improving base width and doping total amount, significantly improve the base electricity and lead, thereby improve f
TAnd f
Max, make f
TAnd f
MaxHave high value simultaneously, and reduce noise greatly.
For achieving the above object, the present invention proposes new physics conception and the corresponding new device structure that a kind of base quantum well transports.Specifically, the present invention adopts following technical scheme, when it is grown in the heterojunction bipolar transistor base, utilize film growth techniques to regulate each component and doping, has non-doping thin layer along the base longitudinal growth is one or more with respect to its both sides than the low energy gap width, can form potential well for the base majority carrier, it is non-doped quantum well, the barrier layer of these non-doping thin layer both sides then mixes, like this, the barrier layer of each non-doping thin layer and its both sides constitutes a quantum well unit, one or more such quantum well unit repeated arrangement, thus in the base, form a kind of modulation doped quantum well structures.
By said structure, can make majority carrier (hole) mainly concentrate on the quantum well region that undopes of base, thereby it laterally transports the raising that mobility almost has the order of magnitude, thereby make r
bReduce significantly with noise, and improve f
MaxSimultaneously, the component that suitably designs the base remainder distributes and doping, can form the accelerating field that minority carrier (electronics) work is vertically transported in the base, reduces the transit time of electronics, improves f
TThereby, adopt quantum well of the present invention base structure after, can on the basis of not improving base width and doping total amount, significantly reduce r
b, make current gain f
TAnd f
MaxHave high value and noise-reduction coefficient simultaneously.
Potential well one side of above-mentioned each barrier layer of the present invention also can be provided with a non-doping separator.Like this, under the buffer action of separator, can make charge carrier avoid the influence of impurity scattering, further improve its mobility.
The present invention is directed to the international difficult problem of each high-frequency parameter mutual restriction of heterojunction bipolar transistor, new physics conception and corresponding new device structure that the base quantum well transports are proposed in the world first, this structure can be improved high-frequency gain effectively on the basis of not improving base width and doping total amount, significantly improve the base electricity and lead, thereby improve f
TAnd f
Max, make f
TAnd f
MaxHave high value simultaneously, and reduce noise greatly.Therefore, solved this international difficult problem of mutual restriction between the device parameters well in theory and in the practice.
Below in conjunction with drawings and Examples the present invention is described in further detail.
Description of drawings
Fig. 1: SiGe/Si type heterojunction bipolar transistor base doping concentration and Ge constitutional diagram in the prior art;
Fig. 2: the SiGe/Si type heterojunction bipolar transistor base doping concentration and the Ge constitutional diagram of another kind of scheme in the prior art;
Fig. 3; The two table top heterojunction bipolar transistor overall structure figure of present embodiment SiGe/Si type;
Fig. 4; The A-A profile of Fig. 3;
Fig. 5: new construction SiGe/Si type heterojunction bipolar transistor base doping concentration and Ge constitutional diagram;
Fig. 6: conventional structure SiGe/Si type heterojunction bipolar transistor base doping concentration and Ge constitutional diagram;
Fig. 7: new device structure majority carrier (hole) distributes and vertical (electronics) drift field schematic diagram;
Fig. 8: conventional device structure majority carrier (hole) distribution schematic diagram;
Fig. 9: new construction SiGe/Si type heterojunction bipolar transistor can be with schematic diagram;
Figure 10: conventional structure SiGe/Si type heterojunction bipolar transistor can be with schematic diagram:
Embodiment
Embodiment:
Below, be objective for implementation with SiGe/Si type heterojunction bipolar transistor, the present invention is done further ocean describe in detail bright.
Ask for an interview Fig. 3, present embodiment selects for use the two table top heterojunction bipolar transistor of a kind of SiGe/Si type as objective for implementation, and it mainly is made of electrode 1, emitter region 2, base 3 and collector region 4.Wherein, as shown in Figure 4, from longitudinal profile, described base 3 includes a high-Ge component (x=0.30, wherein x is the Ge component, down together) non-doping thin layer 7 and is positioned at low Ge component (x=0.1-0.15) barrier layer (5 of non-doping thin layer 7 both sides, 6,8,9), wherein barrier layer (5,6,8,9) in, 6,8 is non-doping separator, and 5,9 is doped layer.In addition, 11 be the Si substrate among the figure.After adopting said structure, the mountain is high more in the Ge component, the energy gap of SiGe layer is narrow more, thereby make the non-doping thin layer of above-mentioned high-Ge component have narrower energy gap with respect to the low Ge component barrier layer of its both sides, can form the potential well for the base majority carrier, promptly non-doping is in trap, but not the barrier layer of doping thin layer both sides (doped layer 5 wherein, 9) then mix, thereby in the base, form a kind of modulation doped quantum well structures.
Fig. 5, Fig. 6 show the base doping concentration and the Ge constitutional diagram of conventional structure and present embodiment new construction SiGe/Si type heterojunction bipolar transistor respectively, from their contrast, can obviously find out, the mountain has formed the quantum well to majority carrier (hole) in the special distribution of Ge component in the new construction SiGe/Si type heterojunction bipolar transistor of the present invention base.
As previously mentioned, the mountain is in the formation of above-mentioned majority carrier (hole) quantum well, make the majority carrier (hole) of base mainly concentrate in the quantum well region that undopes, in addition, the mountain is in the gradual change and the doping gradual change of Ge component in barrier layer, can form the acceleration drift field to injected minority carrier (electronics), this point can be found out from Fig. 7, Fig. 8.Among the figure, 2 is the emitter region, and 3 is the base, and 4 is collecting region, the accelerating field E that → representative is mixed and formed
BThe accelerating field E that, → represent Ge change of component forms
Gc,
Arrow length represents that the base transverse electric leads size, and on behalf of ionization, "-" led, and " " represents the hole.As shown in Figure 8, in the base of present embodiment, because of in well region, not existing ionization to be led, add the effect of separator, when laterally being transported, the hole exempts from the diffuse transmission influence that ionization is led, its mobility is compared the raising that the order of magnitude is almost arranged with the conventional structure base, and the result has improved the base electricity greatly and led, and has significantly reduced base resistance r
bThereby, reduced noise factor, improved f
MaxAnd in conventional structure SiGe/Si type heterojunction bipolar transistor shown in Figure 7 base, majority carrier (hole) is evenly distributed in whole base basically.Led because of a large amount of ionization of highly doped existence of base, the hole laterally transports and runs into very strong scattering, and the base electricity is led less, base resistance r
bVery big.From two figure contrast, also can find, owing to the special distribution of Ge and B doping, have accelerating field E in the new construction minority carrier (electronics)
GeAnd E
B, the result has reduced the Base Transit Time of electronics greatly, thereby has improved f
T, then do not have such accelerating field at conventional structure.
The following outstanding effect that is reached for the above structure devices of the present invention: the new construction technical indicator that this invention has been implemented: conventional structure device technology index: (1) cut-off frequency f
T: 15GHz cut-off frequency f
T: 6GHz (2) leakage current I
Ceo＜10nA leakage current I
Ceo＜10nA (3) low temperature (77K) β: 6300 low temperature (77K) β: 9700 room temperatures (300K) β: 280 room temperatures (300K) β: 330 (4) Early voltages: 500V Early voltage: 410V (5) maximum frequency of oscillation f
Max11GHz maximum frequency of oscillation f
Max4GHz
In sum, quantum well base structure can significantly reduce r on the basis of not improving base width and doping total amount
b, make current gain, f
TAnd f
MaxHave high value and noise-reduction coefficient simultaneously.Resultant effect is the contradiction that has solved HBT multi-parameter mutual restriction internally on the structure, improved every technical indicator of device greatly, the device architecture under the conception of new physics is instructed particularly, make under identical even more weak process conditions, the performance of developing device is compared with ordinary construction and is improved a lot (as high-frequency gain, f
TAnd f
MaxCan improve many times).
Should be pointed out that the above just for implementing the specific embodiment that the present invention designs, obvious, for those skilled in the art, under the prerequisite that does not break away from the principle of the invention, can also make some constructional variant and improvement.As: in the present embodiment, for simplicity, shown in only be provided with a non-doped quantum well thin layer in the base.Certainly, also can in the base, establish a plurality of such thin layers as required.In addition,, respectively be provided with the non-doping separator of one deck, certainly, also can not establish this non-doping separator (effect may be weaker) in potential well one side of above-mentioned each barrier layer of this embodiment.And on structure, the barrier layer of above-mentioned non-doped quantum well both sides both can be designed to same thickness, also can adopt different-thickness as required.In addition, except the described SiGe/Si type of present embodiment heterojunction bipolar transistor, the present invention also can use GaAs/AlGaAs or III-V family and other materials.And transistorized type can be the npn type, also can be the pnp type.More than these do not depart from the scope of the present invention.
Claims (4)
1. heterojunction bipolar transistor, mainly by electrode, the emitter region, the base, and collector region constitutes, it is characterized in that: from the longitudinal cross-section, described base includes one or more non-doping thin layers that have than the low energy gap width, the both sides of these non-doping thin layers are barrier layers that the broad energy gap is arranged, non-doping thin layer can form the potential well for the base majority carrier, it is non-doped quantum well, but not the barrier layer of doping thin layer both sides then mixes, the common formation of the barrier layer of each non-doping thin layer and its both sides one quantum well unit, one or more such quantum well unit repeated arrangement, thus a kind of modulation doped quantum well structures in the base, formed.
2. heterojunction bipolar transistor according to claim 1 is characterized in that: respectively be provided with a non-doping separator between the barrier layer of described non-doping thin layer and its both sides.
3. heterojunction bipolar transistor according to claim 1 and 2 is characterized in that: described transistor can be used the SiGe/Si material.
4. heterojunction bipolar transistor according to claim 1 is characterized in that: described transistorized type can be the npn type, also can be the pnp type.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 99109641 CN1111313C (en) | 1999-07-02 | 1999-07-02 | Bipolar heterojunction transistor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 99109641 CN1111313C (en) | 1999-07-02 | 1999-07-02 | Bipolar heterojunction transistor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1238563A CN1238563A (en) | 1999-12-15 |
| CN1111313C true CN1111313C (en) | 2003-06-11 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 99109641 Expired - Fee Related CN1111313C (en) | 1999-07-02 | 1999-07-02 | Bipolar heterojunction transistor |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005522883A (en) * | 2002-04-05 | 2005-07-28 | コピン・コーポレーシヨン | Bipolar transistor with graded base layer |
| US6764918B2 (en) * | 2002-12-02 | 2004-07-20 | Semiconductor Components Industries, L.L.C. | Structure and method of making a high performance semiconductor device having a narrow doping profile |
| US7989844B2 (en) * | 2003-02-18 | 2011-08-02 | Nxp B.V. | Semiconductor device and method of manufacturing such a device |
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1999
- 1999-07-02 CN CN 99109641 patent/CN1111313C/en not_active Expired - Fee Related
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