CN1159490A - Compound semi-conductors and controlled doping thereof - Google Patents

Abstract

A method of controlling the amount of impurity incorporation in a crystal grown by a chemical vapor deposition process. Conducted in a growth chamber, the method includes the controlling of the concentration of the crystal growing components in the growth chamber to affect the demand of particular growth sites within the growing crystal thereby controlling impurity incorporation into the growth sites.

Description

Compound semiconductor and controllable doped

The application is the continuation application that proposed and be published as November 7 nineteen ninety-five the Application No. 276599 (continuation application of the Application No. 008650 that it is now having abandoned of proposing on January 25th, 1993) of the American Communications patent No. (United States Letters Patent Number) 5463978 on July 18th, 1994.

The present invention relates to the controllable growth of high quality semiconductor device crystal film, relate to more precisely and be used for height and can repeatedly produce the method and system of high quality manufacturing silicon carbide semiconductor.The present invention is supported under the government contract that NASA provides by government to finish.Government enjoys certain right to the present invention.

Be that the American Communications patent No.5363800 of " in the technique of the many types of monocrystal thin films of controllable growth carborundum on the silicon carbide wafer " (Process For The Controlled Growth OfSingle-Crystal Films Of Silicon Carbide Polytypes On Silicon CarbideWafers) and the exercise question issued on September 28th, 1993 are that the American Communications patent No.5248385 of " the isoepitaxial growth technique of single crystal silicon carbide on the silicon carbide wafer " (Process ForThe Homoepitaxial Growth Of Single-Crystal Silicon Carbide Films OnSilicon Carbide Wafers) classifies reference as with the exercise question of on November 15th, 1994 issue, the two has all told about the preliminary treatment of silicon carbide substrates herein. To have two kinds or more multi-component crystalline position competition epitaxy technology in order illustrating, also to have listed the American Communications patent No.5463978 of the exercise question of issue on November 7 nineteen ninety-five herein in for " compound semiconductor and controllable doped " (Compound Semiconductor And ControlledDoping Thereof).

The present invention is particularly suitable for producing carborundum crystals (being used to comprise crystal film here) and will discusses with reference to it especially; But the present invention has much more extensive purposes and can be used for other crystal that chemical vapor deposition process is grown.

Semiconducter device is used in the various electronic application.Semiconducter device comprises diode, transistor, unicircuit, photodiode and charge coupled device.Adopt the various semiconducter device of silicon or the compound semiconductor such as gallium arsenide (GaAs) and gallium phosphide (GaP) to be widely used.In order to make semiconducter device, must be able to grow has controlled impurity and mixes (with regard to net concentration and concentration distribution) and the high quality of processing surface of good pattern and the monocrystal thin films of fabricating low-defect-density.In recent years, increasing to the research interest of the manufacturing silicon carbide semiconductor that is used for high temperature, superpower and/or high radiation working conditions (under this condition, silicon and conventional III-V semi-conductor can't be worked satisfactorily).

Silicon carbide is classified as compound semiconductor, and it has the superior semiconducting behavior of potential that is used for relating to high temperature, superpower, high radiation and/or high-frequency application.Silicon carbide has some makes its special superior characteristic in various application.These advantages comprise the wide bandgap that is about 2.2-3.3eV, high thermal conductivity, low specific inductivity, high saturated electron drift velocity, high breakdown electric field, low minority carrier life time and high decomposition temperature.And silicon carbide is thermally-stabilised, chemically stable and mechanically stable, and has the ability of very strong radioresistance injury reinforcing.In addition, can make also and can under the temperature more than 600 ℃, work with silicon carbide such as the various optics of photodiode (LED).Although sic semiconductor device has this many advantages and ability, lack control the large-scale commercial of silicon carbide device is made slow progress owing to crystal mass, growth repeatability and doping agent are entered to carborundum crystals controlled.

Some character of SiC has caused the shortage of this control.At first, it does not melt under rational pressure and is being higher than under 1800 ℃ the high temperature and distils.Secondly, its growth is called many types of a lot of different crystalline structure.The 3rd, the back doping (post-growth) of in the SiC crystal, growing (that is, diffuse into crystal as employed in Si industry from gaseous substance) inoperative.Doping techniques after other growth of knowing (promptly ion implantation) all causes tangible lens lesion usually.With after annealing method (post-annealing) thus remove performance various that these lens lesions improve device and attempt generally all to cause serious doping agent redistribution.

Because melt SiC (molten-SiC) growing technology can not be used for SiC, so developed two kinds of growth SiC crystalline technology.First kind of technology is called chemical vapour deposition (CVD), wherein reactant gases introduced the crystal chamber so that make the SiC crystal on suitable warmed-up substrate.Second kind of growth bulk SiC crystalline technology is commonly referred to distillation (sublimation) technology or Lely technology.In sublimating technologe, certain solid SiC material rather than desirable specific many types of monocrystalline are used as starting material and its heating are distilled until solid-state SiC.Make the materials evaporated condensation to produce required crystal then.Though can both obtain a large amount of crystal with sublimation method or epitaxial growth method (CVD), be difficult to prepare big SiC monocrystalline and be difficult to control accurately SiC crystalline size, shape, many types of and doping.

The SiC crystal exists with six sides, trigonometric sum cubic crystal structure.Usually, the cubic structure with zincblende lattce structure is called β-SiC or 3C-SiC, and the many types of α-SiC that is referred to as of various six sides and triangular form.Prevailing α-SiC is many types of to be 6H-SiC.During various SiC are many types of each all has its unique electricity and optical property, makes it be better than the many types of of other in specific application.For example, 6H-SiC is many types of to have band gap and a hexagonal structure that is about 2.9eV, and 3C-SiC is many types of to have the less band gap that is about 2.2eV and than the many types of higher symmetrical structure of 6H-SiC.These nature difference cause 6H-SiC advantage in some applications, and for example the band gap of broad causes blue LED and can work under higher temperature.On the other hand, 3C-SiC is many types of to have higher electronic mobility, causes higher operating frequency.

The many types of method with double-deck Si of stacking and C atom of SiC forms.Each bilayer can be arranged in of three positions.The order of stacking has determined specific many types of.The direction of stacking is called crystal C axle, and it is perpendicular to base plane.For 6H-SiC, known (0001) face (Si face) or (0001) face (C face) are base planes, and for 3C-SiC, (111) face is equivalent to (0001) base plane.

On the 6H-SiC of dislocation, stacking fault, microtwinning, double-deck location border (DPB), helical dislocation and antiphase boundary (APB) better quality seldom and 3C-SiC crystalline growing technology, a lot of progress have been obtained.

U.S. Patent No. 5037502 (Suzuki) discloses the technology of a kind of produce single crystal SiC, and its method is the single crystal film of α-SiC of growing on β-SiC single crystal film in the CVD chamber.Suzuki announces, when growth β-SiC crystal, the CVD reaction chamber should remain between 1400-1900 ℃, and preferably remains between 1500-1700 ℃.Silane (SiH ₄) and propane (C ₃H ₈) be source gas, send into the growth room with the Si/C atom number ratio of 0.01-10 (preferably 0.5-5).In crystal growing process, the Si/C ratio is decided to be constant.The Si/C ratio is set in single optimum point and makes the crystal growth maximum, makes lattice defect minimum with growth β-SiC crystal simultaneously.By means of keep similar Si/C than and the temperature of growth room dropped to 800-1200 ℃ (preferably 1000-1100 ℃), the α-SiC crystal of growing on β-SiC crystal.Suzuki announces that β-SiC crystal must be in the temperature between 1200-1400 ℃ (preferably 1300-1350 ℃) growth down.By means of growth room's temperature is dropped to below 1200 ℃, the α-SiC crystal of can only growing.Suzuki has only pointed out the SiC crystalline type that temperature effect can be grown.Suzuki did not announce that (1) is any β or α-SiC crystal was carried out adulterated method, (2) the pretreatment technology before growth α-SiC crystal such as preparation β-SiC crystalline any kind, (3) whether the inclination of β-SiC substrate can influence α-SiC crystalline growth, and the certain surface of (4) β-SiC substrate better α-SiC crystal of whether growing.

In growth 3C-SiC and 6H-SiC crystal, have all these advantages, but controlled purity of these crystalline and doping are limited.And, can't realize that still controlled repeatably degeneracy mixes or low-down doping.Entering of doping agent is considered to intentionally that impurity enters in the growing crystal, enters crystal and is considered to unintentionally that impurity enters (promptly staiing) and stain.In distillation or CVD crystal growth technique process, all cpds and/or element are all had a mind to and are by mistake entered into crystal.The limited various technology of success ratio have been used to get rid of from crystal and have stain to produce high-purity crystal.

Be entitled as in the paper of " impurity enters β-SiC film in the epitaxial process theory and empirical studies " (Theoretical and Empirical Studies ofImpurity Incorporation into β-SiC Thin Films During EpitaxialGrowth) (1986) has announced and a kind of the SiC crystal has been carried out adulterated technology at H.J.Kim and R.F.Davis.In the document of Kim, announced that relevant doping agent enters the research of β-SiC.The article of Kim points out that when the concentration of dopant in the SiC growth reactor increased, the doping agent in β-SiC crystal entered also and increases.Kim points out that also the concentration that enters of some doping agent is higher than theoretical expectation.The viewed high unexpectedly concentration that enters of Kim, more determined as SIMS and electronic probe result, be assumed that what three kinds of possibilities caused, that is: (1) has notified the impurity trap of line in material or point defect and/or dislocation and stacked layers fault, (2) doping agent-Si and/or doping agent-C interacts, and (3) non-electroactive calking bit position.Kim think doping agent-Si and/or doping agent-C interact with each doping agent 1) not ionization or be positioned at non-electroactive locational or 2) relevant with the position of Si or C composition complex compound (complex).The term of Kim " is formed complex compound with Si or C " and is pointed out that dopant atom can combine the visibly different compound that composition has non-electrical feature with obtainable Si and/or C in the SiC crystal, thereby produces difference between the element doping agent concentration that doping content that electricity records and atom-probe (being SIMS) obtain.The complex compound of these hypothesis is such as compound silicon nitride (Si ₃N ₄) and so on the inclusion of compound.The materials with high melting point of mentioning in the Kim article is that fusing point is 1900 ℃ Si ₃N ₄About non-electroactive calking bit position, Kim thinks that dopant atom also can be arranged in other non-electroactive position.Specifically, Kim refers to " the non-electroactive calking " position in the lattice.Kim points out that some atom (for example Al and P) is obeyed ideal and mixed behavior, and other (are N, B) because to estimate that than theory much higher concentration enters the SiC crystal of growth and not to be so significantly.In a word, Kim points out that the excessive dopant in β-SiC crystal enters and believes mainly and caused by following factors: (1) non-electroactive adulterant atom is in the accumulation at the defective locations place such as dislocation and stacking fault, (2) the non-electroactive high melting compound that forms by the interaction of dopant atom and SiC and/or C, the perhaps accumulation of (3) dopant atom non-electroactive calking position in the SiC lattice.Because the high density of defects among β-SiC (being grown on the Si substrate) is to abandon one of main reason of growing on superior SiC substrate, above-mentioned three possible to be interpreted as SiC growth field well-known.Kim does not have to announce any technology of controlling the admission rate of foreign atom in the SiC crystal by means of change Si/C source gas ratio.The research of Kim is with maintenance Si in the whole crystal growing process and C source gas ratio is constant and the method for change concentration of dopant is carried out.The theory that Kim discussed is considered and experimental data does not provide any opinion that enters that how to influence doping agent in the growing crystal about the variation of Si in the crystal growing process and C source gas ratio.The research of Kim only only limits to when having the different dividing potential drop of doping agent in the reactor influence to the concentration of dopant in the growing crystal.Kim does not point out that crystal growth Once you begin will change the dopant gas in the reactor yet.The all experiments and the data of collection are all from the crystal growth based on constant Si, C and dopant gas concentration.Kim does not announce the change of any gas in the reactor in the crystal growing process.

Be used for InP and another technology of GaAs CVD growing system of report are to adopt barrier technique, thereby plane of crystal is stopped or shield impurity with quite a large amount of crystalline compounds.See " In-H ₂PCl ₃Process chemistry (Chemistry of The In-H ₂PCL ₃Process) " (R.C.Clarke; Inst.Phys.Conf. No.45; 1979; 19-27) and " the doping behavior of silicon and vapour growth III-V epitaxial film (Doping Behavior of Silicon and VaporGrowth III-V Epitaxial Films) " (H.P.Pogue and B.M.Quimlich; J.Crystal Growth; 31,1975,183-89).Enter though barrier technique has reduced the contamination in the crystal, need to use a large amount of crystal growth compounds to realize stopping that this has detrimentally affect to crystal mass and surface topography.Except the problem relevant with staiing removing, the crystal of controlled suitable lower concentration doping intentionally yet is unreachable to and/or is not reproducible.And, the also not control and/or repeat that the abrupt dopant agent concentration distributes in the crystal technology of (promptly from the P type to the n type, degeneracy is to light dope).

In the CVD crystal growth, the control of source gas only is used for setting in order to obtain the single best source gas ratio that level and smooth single-crystal surface pattern prevents to form undesirable crystal (being the polycrystalline Si C in the SiC crystal) and other lattice defect simultaneously in the prior art.The understanding of CVD field of crystal growth points out to oppose to change in the crystal growing process source gas ratio.Believe and at first must obtain the best source gas ratio so that obtain high quality crystal.Source gas ratio setting point is once obtaining, and just entering of doping agent only controlled with the concentration of dopant of controlling in the reaction chamber.Prior art points out that the doping agent that the change of source gas ratio does not influence growing crystal enters (that is electrical properties).This best source gas ratio just keeps consistently and is concrete and clear and definite to each CVD system in whole crystalline process of growth once determining.The constant number that is controlled of Si source that prior art is pointed out and C source gas causes can be used to entering crystal growth atom (being Si and C atom) or the Si position (site) of dopant source atom (for example Al, N, Ga, Ti, V, Na, Fe, P, S, O, B, the F etc.) constant ratio (being that the constant position is formed) to the C position.Because P type dopant atom with the available Si position of Si source atom contention fixed qty, is fixed so enter the peak concentration of growth SiC crystalline P type doping agent.When in order to obtain than this fixed amount (p=6 * 10 ¹⁷Cm ^-3) higher carrier concentration and when increasing the quantity of Al dopant source, excessive Al causes being deposited on and contains the Al material on the reactor wall, and it causes P type heavy doping (P=1.6 * 10 of accurate polycrystalline film ¹⁹Cm ^-3) very coarse surface.Therefore, can not grow carrier concentration greater than P=6 * 10 ¹⁷Cm ^-3P type (for example Al mixes) single crystal film that mixes.

Developed and tried out the various art methods that impurity enters in the control growing SiC film of attempting.For example, molecular beam epitaxy (MBE) adopts ultra-high vacuum system and utilizes the molecular flow on the warmed-up substrate of focusing on of bunchy to cause crystal growth.This technology provides the control to a certain degree to dopant-concentration profile really.But low growth velocity is a main drawback and some problem is arranged.At first, because growth velocity is very low, so its commercialization is unpractical.The second, the restriction of the purity that the entering of impurity still is subjected to source gas and the degree of cleaning of growth response chamber.And the problem that the low-down speed of growth enters impurity increases the weight of.

Be used for that SiC is carried out adulterated another kind of technology and adopt ion implantationly, this is a doping techniques after a kind of growth that is used for introducing required doping agent.Referring to " broadband electric capacity, III-V nitride and II-VI Zn-Se based semiconductor device technology (Large-Band-Cap; III-V Nitride; andII-VI Zn-Se-Based Semiconductor Device Technologies) " (Morkoc etc., J.App.Phys.76 (3), 1368 (1994)).This method makes crystalline structure produce a large amount of damages and requires the after annealing step to reduce the high density of defects (it seriously influences the quality of device) that this technology produces usually.And, the SiC crystal only partly effectively the result of the desired unusual high temperature (＞1800 ℃) of annealing be that the concentration of P type doping agent changes 4 times (4 *) and n type doping agent owing to external diffusion has been lost.

When needs degeneracy doped layer, for example when the needs metal contact layer, obtain the restriction that degeneracy P type is subjected to problem such as the gas-phase nucleation that causes the extreme difference film morphology (from required excessive high P type source gas) by CVD.

As mentioned above, SiC is just becoming a kind of be used for the making superpower that is suitable for being operated in high temperature, high irradiation and the corrosive atmosphere and/or the selection material of microwave frequency semiconducter device.In the development of superpower that is used for high temperature, corrodibility and high radiation environment and high frequency semiconductor devices, the intrinsic material advantage of SiC is just appeared now.These microelectronic devices comprise high pressure Schottky rectifier and power metal-oxide compound semiconductor field-effect transistor (MOSFET), microwave and millimetric wave device and high temperature radioprotective junction type field effect transistor (JFET).But,, still need aspect two of the bulk-growth of SiC and epitaxys, make progress for the advantage of the employing SiC of theoretical calculation is fully realized.For example, the bulk-growth that need improve SiC for the micropore and the microchannel of abatement device restriction.The progress that in epitaxial growth technology, needs other.The doping agent that particularly must understand and control reliably in the SiC outer layer growth process enters.In order to realize the superior high temperature semiconductors character of inherent of SiC in advanced person's electronic device applications, necessary improvement is to the control of the Electronic Performance of the epitaxial film of chemical vapour deposition (CVD).Before this work, the control that CVD SiC epitaxial film doping agent is entered is limited, and it repeatably mixes and generally is confined to the n type is N _D=2 * 10 ¹⁶Cm ^-3-5 * 10 ¹⁸Cm ^-3, and P type 6H-SiC epitaxial film is N _A=2 * 10 ¹⁶Cm ^-3-1 * 10 ¹⁸Cm ^-3The doping content scope.With the range extension of repeatably mixing to comprising that lower concentration just might make thousands of volts SiC power device, and as can obtain higher doping content, the device that can cause performance to be improved then because dead resistance is lower.

Because it is improper to can be used to control the technology that doping agent in the crystal of CVD technology growth and/or contamination enter, just require a kind of can be from the crystal of CVD growth the method for despumation optionally.

The present invention relates to a kind of growing high-quality crystal and the method that enters of control impurity or doping agent in crystal growing process.

According to principal feature of the present invention, provide the system and method for the quantity of chosen elements in the given vitellarium of crystalline that a kind of control is deposited on chemical vapour deposition (CVD) method growth.One class growing crystal is the SiC crystal, and wherein silicon (Si) is deposited in the Si growth position and in the C growth position of carbon deposition in the vitellarium.Selected element is in the SiC crystal growing process or fight for the Si growth position, perhaps fights for the C growth position.The improvement of being done comprises the gaseous state Si compound that makes first quantity and flows through the growth room and make the gaseous state C compound of second quantity flow through the growth room and the Si compound of controlling first quantity is deposited on the quantity of the chosen elements in the crystal growth district SiC of the place crystal with control with respect to the ratio of the C compound of second quantity.Selected element is a kind of impurity and or a kind of doping agent or a kind of contamination.

Crystal growing chamber is used the cause chemical vapour deposition and growing crystal.Crystal growing chamber comprises the crystal growth district of a growing crystal on it.Crystal growing chamber can comprise that also a heating unit is with the indoor temperature of control crystal growth.Introduce the growth room and at the indoor making crystal of crystal growth by means of crystal growth compound that will evaporation.Available carrier gas is incorporated into the crystal growth compound in the crystal growing chamber.In crystal growing chamber, can grow many dissimilar crystal such as silicon carbide, gallium arsenide, gallium phosphide etc.The crystal of growth forms by being deposited on the locational crystal composition of crystal growth.For example, the SiC crystal is grown by means of silicon compound and carbon compound being introduced in the crystal growing chamber.In crystal growing chamber, carbon atom is decomposed out by the original chemical of carbon compound and Siliciumatom is decomposed out by the original chemical of silicon compound.Grow into the SiC crystal by the Siliciumatom that is deposited on the carbon atom in the carbon location and be deposited in the silicon position then.The SiC crystal is made up of the Si of stacking and C atom bilayer or thin film layer.Each thin film layer is made up of the C atom that one deck is bonded to one deck Si atom.Because the double-deck stacking of SiC thin film layer, the SiC crystal just has a Si face and a C face.The crystal growth position, for example SiC crystalline C position and Si position, it is highly specific can entering during crystal growth aspect these positions at the atom of what type or molecule.The high specificity of crystal growth position partly is because the physical structure of these positions.Each atom and molecule all have a distinct size and atomic structure.Unless the size of atom or molecule and structure and crystal growth position are same or similar, otherwise atom or molecular linkage are just very little to the probability of growth position.Crystal growth position specificity also is subjected in the growth position or near the influence of linkage force.Each atom and molecule have an Elektronenschale that has some electric charges, and near the atom that exists it and the growth position or the Elektronenschale of molecule interact, thereby or attracted to growth position or be excluded from growth position.By means of the impurity deposit in the growth position in the control crystal growing process, can control any crystalline purity of CVD technology growth.In crystal growing process, specific growth position has a special demand to the atom or the molecule of competition.By means of near the competitive atom the control growing position or the quantity of molecule, demand that can the control growing position.Control between crystal atoms component and impurity atoms or the molecule contention by means of the concentration of various atoms in control growing position or molecule to the particular growth position.This notion is called position competition extension (site-competition epitaxy) herein, it can be used for improving the repeated doping scope of expanding n type and P type CVD crystal epitaxial layer simultaneously greatly of CVD crystal epitaxial layer.Curiously, by means of the ratio of controlling the crystal growth compound of introducing crystal growing chamber, accurately and repeatedly control growing position competition.The many crystal with two or more a plurality of growth positions except that the SiC crystal all can enough CVD technology be grown potentially, and can control entering of impurity with position competition technology.Pay attention to and carry out growth position competition technology obtaining the move place and the control of the crystal film growth conditions more much bigger, so that in crystal growing process, optimize crystal growth rate, surface topography, Impurity Distribution and other film characteristics than prior art.

According to a generalized situation more of the present invention, provide a kind of system and method that is deposited on the quantity of the noncrystal element in the given vitellarium of being formed by at least two kinds of crystal elements of crystalline with the CVD technology of carrying out in growth room control when the crystal growth district growing crystal.Crystal comprises the first crystal element and the second crystal element, and the crystal of growth has two kinds of crystal growth positions at least.The first crystal element is deposited in the first crystal growth position, and the second crystal element is deposited in the second crystal growth position.Noncrystal element is fought at least a growth position.The method of having improved comprises the gaseous state crystal element compound that quantity is controlled and flows through the growth room, wherein every kind of crystal element compound comprises a kind of crystal element at least, and the ratio of the gaseous state crystal element compound that is controlled of controlling the size is deposited on the quantity of the noncrystal element in the crystal particular growth position in the crystal growth district with control.Noncrystal element is a kind of impurity such as doping agent or contamination.Crystal can be elementary composition to form the crystal of types such as binary, ternary by two kinds, three kinds, four kinds or more kinds of crystal.Every kind of crystal element is deposited in a kind of specific crystal growth position.Noncrystal element is fought for at least a specific crystal growth position.Because the geometrical dimension of noncrystal element and the geometrical shape and the electric charge of electric charge and crystal growth position, noncrystal element is general only to be competed with a kind of crystal growth position.If a kind of noncrystal element can be deposited in more than one the crystal growth position, noncrystal element has the avidity more much bigger than other position to a certain usually.The crystalline type that might grow comprises ZnSe, GaAs, InP, In _xGa _1-xAs, GaAsP, GaP, InAs, In _xGa _1-xAs _yP _1-yDeng.

According to another kind of situation of the present invention, dopant material is introduced into crystal growing chamber, and controls the admission rate of doping agent in the crystal in crystal growing process.Various types of dopant materials can be used to form n type or the P type layer in the crystal.The crystalline dopant distribution is very important for the sort of electron device that wherein is combined with doped crystal.Dopant material or be introduced into the growth room with its pure form (being nitrogen) or with the form (being triethyl aluminum) of the compound that comprises the dopant material that is bonded to the doping agent original chemical.The dopant material that is introduced into the growth room is chosen to make dopant material that at least a crystal growth position is had avidity.Because the physical property of doping agent and growth position, nearly all doping agent all only have avidity to a kind of growth position.Can be bonded in a few doping agent in the multiple crystal growth position compares other growth position to a kind of growth position bigger avidity is arranged.In a single day dopant material is introduced into crystal growing chamber, and a kind of specific growth position is fought in the main allomeric elementary composition of dopant material.Dopant material allomeric atomic composition is controlled by means of the obtainable growth position of control the contention (being demand) of a kind of particular growth position.The control of growth position demand is realized by the ratio of regulating each the crystal atoms component in the crystal growing chamber.By means of the ratio of the various crystal atoms components of appropriate control, the particular growth position that can be used for dopant material in crystal growing process will become many or tail off, thus the influence dopant-concentration profile in control growing locational requirement and the particular crystal also.

According to another situation of the present invention, crystal growth on pretreated substrate with expansion growing high-quality crystalline growth parameter(s).Substrate can also can can't help to form with the crystal film identical materials of being grown.The crystal film that is grown on the substrate can iso-epitaxy (substrate has identical crystal element and structure with crystal film) growth or hetero epitaxy (substrate has different crystal element and/or structure with crystal film) growth.Substrate is pretreated so that remove the impurity may cause the imperfect crystal film during crystal growth from substrate surface.On substrate surface, exist the position of contamination or defective or some other surface distortion that anomalous crystal growth may take place.These contaminations or defective cause undesirable nucleation, cause having the crystal of undesirable multi-structure, undesirable appearance pattern, stacking fault, APB, dopant distribution inferior, high contamination concentration etc.By means of cutting and polished substrate surface rightly and subsequently substrate surface is corroded and will stain with surface imperfection and dispose from substrate.The mode that corrosion is carried out does not change substrate surface, can not damage the crystal growth on the substrate surface.The substrate surface of the low defective of cleaning has been expanded growing high-quality crystalline working parameter surprisingly.By means of the physical influence that reduces crystal growth technique, the Si/C concentration rate in the aforesaid growth room is limited in certain limit and really not away from narrow ratio ranges, and this depends on selection to used hydrocarbon polymer (to SiH ₄/ C ₂H ₄Be Si: C=1: 1, to SiH ₄/ C ₃H ₈Be Si: C=2: 3).Adopt arbitrary given crystal growth technique, the physical influence factor to this technology is all arranged, be temperature, pressure, crystal composition concentration, concentration of dopant, impurity concentration, growth surface etc., these all influence the crystal film layer in the process of growth.The caused influence of substrate surface of eliminating in crystal growing process or reducing defective and/or stain makes and might do bigger change on the physical influence level from other physical influence factors.The reduction that causes by pretreated substrate physical influence make it possible in the growth room, use bigger crystalline compounds ratio ranges to strengthen the control that impurity in the crystal is entered.

According to another situation of the present invention, a kind of method of growing crystal is provided, thereby crystal growth on the particular surface of substrate to reduce physical influence to crystal growth system.The crystalline structure of the substrate of forming from two kinds or more kinds of not homoatomic has at least three kinds of different faces.The substrate of being made up of the Si-C crystal has a silicon face (Si face), a carbon face (C face) and a carbon-silicon face (A face).Each face of crystalline structure all has different physical property (for example polarity), and it can increase or reduce the physical influence to crystal growth system, and this is grown in crystalline quality on the substrate surface with influence.

Main purpose of the present invention provides a kind of repeatably method of crystal film of chemical vapour deposition growing high-quality of using.

Another object of the present invention provides a kind of method that impurity enters the crystal film layer in the crystal growing process that is used for controlling.

Another purpose of the present invention provides repeatably crystalline method of the high quality that a kind of growth has required Impurity Distribution, low defective.

Another object of the present invention provide a kind of on the pretreated substrate of having removed contamination and surface imperfection from the substrate surface of waiting to want growing crystal from it the method for growing crystal.

Another object of the present invention provide a kind of on the certain surface of substrate the method for growing crystal have the high quality crystal of low defective and smooth surface pattern with growth.

Another object of the present invention provides a kind ofly carries out the adulterated method of degeneracy to P type and the n type epitaxial film with high-quality surface pattern and low defective.

Another object of the present invention provides the crystalline method that very precipitous change is arranged in a kind of grow doping agent n-p type distribution.

Another object of the present invention provides the method at the very precipitous dopant distribution interface of a kind of growth.

Another object of the present invention provides a kind of method that the monocrystalline of defective, low concentration doping is hanged down in growth on various substrates.

Another object of the present invention provides a kind of crystalline method that has precipitous change in the dopant-concentration profile that is grown in.

Another object of the present invention provides the method that a kind of growth has the low imperfect crystal of high quality of gradual dopant distribution.

Another object of the present invention provides a kind of method that can be used to the low imperfect crystal of growing high-quality that increases the concentration rate scope.

Another object of the present invention provides the method that a kind of growth has the low imperfect crystal of high quality of very high concentration of dopant.

Read following description taken together with the accompanying drawings, it is more obvious that these or other purpose and advantage will become concerning person skilled in the art.

Fig. 1 is according to the also synoptic diagram of the CVD system of doped crystal that is used for growing of the present invention;

Fig. 2 is the orthographic plan that has been divided into the substrate of selected vitellarium;

Fig. 3 is the floor map that has the selected vitellarium of parallel lines, shows some atomic scale growth step;

Fig. 4 synoptic diagram has illustrated the 6H-SiC film isoepitaxial growth on the 6H-SiC substrate.

Fig. 5 is a 6H-SiC crystalline orthographic plan, shows the crystalline spatial axes;

Fig. 6 is the sectional view of SiC substrate, shows Si face, C face and the A face of substrate;

Fig. 7 is the sectional view that the 6H-SiC substrate of 3C-SiC nucleation is arranged;

Fig. 8 is a substrate shown in Figure 7, shows the expansion of a 3C-SiC growth nucleation site from the 6H-SiC substrate;

Fig. 9 shows the position competition of C position and Si position in the SiC crystal growing process;

Figure 10 is crystalline dopant-concentration profile figure;

Figure 11 is grown in the SiC crystalline P type on the SiC substrate and the sectional view of n type epitaxial film; And

Figure 12 shows 3C-SiC crystalline forward and reversible circulation～voltage characteristic (logarithmic scale) under several temperature.

Referring now to accompanying drawing, these accompanying drawings are just in order to illustrate most preferred embodiment of the present invention rather than in order to limit the present invention, the invention describes a kind of chemical vapour deposition (CVD) method of having improved, the CVD film impurities is entered with the control of dopant distribution and improves the quality of the crystal film that growth obtains in order to improve.Though this method can be used for many different crystal, will grow with silicon carbide (SiC) crystalline specifically describes this method.The CVD method of having improved comprises pre-processed substrate, in reaction chamber heated substrate, introduce carrier gas, make the evaporation of crystal growth compound, the compound of evaporation introduced reaction chamber, made energy level suitable in the reaction chamber and the flow of material keep the sufficiently long time to have required smooth-flat-surface pattern, uniform thickness, fabricating low-defect-density with growth and the crystal film of the Impurity Distribution that is controlled by means of carrier gas.Crystal can be had a mind to mix to form n type and/or P N-type waferN.This CVD growing method that has improved is based on following discovery, and the impurity in the SiC thin film layer of promptly growing enters the ratio of the silicon compound in the reaction chamber in the process of growth (original chemical that contains Si) and carbon compound (original chemical that contains C) very responsive.By means of changing on the crystal growing surface or near the Si/C compound ratio it, the impurity in can the control growing crystal film enters.

Method of the present invention can be used similar in appearance to Si, SiC and used conventional chemical vapour deposition (CVD) system of GaAs semiconductor technology and carry out.Used gas is hydrogen (as carrier gas), silane (as the Si source), HCl (being used for cleaning and the corrosion substrate surface), propane (as the C source), nitrogen (N in the SiC CVD system ₂, as n type doping agent) and triethyl aluminum (TMA) (as P type doping agent).Other gas can or be used for to crystal doping as Si source or C source.If organic compound is used as Si source and C source, then this technology is commonly referred to metal-organic chemical vapour deposition (MOVPE).Anyly can under high-purity condition, provide the CVD system of these gases to may be used to method of the present invention to suitable reaction chamber with appropriate flow.

Referring now to Fig. 1, show the partial schematic diagram of the suitable CVD reactive system that is used for carrying out technology of the present invention.The CVD reactive system comprises the reaction chamber 22 that has double-walled silica tube (quartz inner pipe can by water-cooled).The internal diameter of reaction chamber 22 is 50mm preferably.SiC substrate 24 is supported by the graphite bearing 26 that SiC applies, and 26 are supported by quartzy rest 28 again.In order to produce the surface temperature of desirable substrate 24; Reaction chamber 22 placed around radio frequency (RF) ruhmkorff coil 30.Ruhmkorff coil 30 provides power by frequency generator 31.The RF field that is produced by ruhmkorff coil 30 is heated to substrate 24 temperature required by means of bearing 26.When growth SiC thin film layer, substrate 24 is the SiC substrate preferably.With main pipe line 33 the gaseous state crystalline compounds is introduced reaction chamber 22.Main pipe line 33 is positioned at an end of reaction chamber 22 and guiding gas and flows through substrate 24 along direction G and flow out from the other end of reaction chamber 22.Various gaseous state crystalline compounds are connected to main pipe line 33, and come adjustments of gas stream with valve 34 that is connected in each gas pipeline and setter 35.Pipeline 36 is silicon gas pipelines that the control silane flow is gone into main pipe line 33, and pipeline 37 is carbon gas pipelines that the control propane stream is gone into main pipe line 33.With pipeline 38 and pipeline 39 doping agent is introduced main pipe line 33.Pipeline 38 is n type doping agent pipelines and preferentially controls nitrogen (N ₂) flow.Pipeline 39 is P type doping agent pipelines and preferentially controls triethyl aluminum (TMA) flow.Carrier gas channel 31 is brought all gaseous state crystalline compounds and doping agent into reaction chamber 22 by main pipe line 33.Carrier gas is hydrogen (H preferably ₂) and so on gas.Carrier gas channel 31 partly turns into the line 31a with supply line 39, makes carrier gas can pass through liquid TMA bubbling.The vacuum pipe V that is connected in vacuum can be connected to main pipe line 33 so that reaction chamber 22 is bled.

Substrate 24 preferably carries out pre-treatment to remove contaminations all on the substrate surface or impurity so that the low defective epitaxial film of easier growing high-quality.Prepare SiC substrate 24 with method from the section of SiC base.Substrate 24 can be cut into and depart from a certain inclination angle of base plane slightly.If will be on α-SiC substrate 24 heteroepitaxial growth 3C-SiC thin film layer, then this pitch angle is preferably less than 1 °, and need carry out extra surface preparation.If will be on SiC substrate 24 isoepitaxial growth SiC thin film layer, then this inclination angle is more preferably greater than 0.1 °.As shown in Figure 5, vergence direction preferably towards＜1100＞or＜1120＞direction so that obtain the SiC epitaxial film on the substrate 24 of growing in of optimum growh speed and best in quality.The most handy diamond paste in surface of substrate 24 carries out single-sided polishing.As shown in Figure 6, SiC substrate 24 has three faces: Si face 50, C face 52 and A face 54.Arbitrary surface all can be polished and prepare and is used for the SiC outer layer growth.Preferably polish Si face 50 and be used for epitaxy.Found that Si face 50 can obtain the highest epitaxial film film of quality, its surface topography is best and defective is minimum.

If select hetero epitaxy, then by means of the method for on substrate 24 surfaces, making border or groove 62 formation vitellariums 60 substrate 24 is further prepared as shown in Figure 2.The groove 62 the most handy precise cutting that have the thin blade of 25 μ m of formation growth sector boundaries 60 are sawed and are cut to reduce lens lesion as far as possible; But border 62 also can use other technology such as photoetching, ion etching and/or photochemistry or electrochemical corrosive process to make.The width of groove 62 only needs less than 1 μ m, but also can use bigger width.The degree of depth of raceway groove 62 preferably is about 50 μ m, but more greatly or smaller also passable.

Substrate surface is once polishing and produce vitellarium 60, just substrate 24 is put into reaction chamber 22.Before growing crystal thin film layer on the substrate 24, substrate is carried out pre-treatment to remove the contamination and the defective of the undesirable heterogeneous nucleation position effect that can play the SiC thin film layer on the substrate surface with corrosion before the growth.In the cutting and polishing process of substrate, can on substrate surface, produce this defective.Corrosion preferably includes in reaction chamber substrate 24 is carried out HCl gas and H before the growth ₂High-temperature gas corrosion in the mixture.To monitor this corrosion, not make and introduce undesirable heterogeneous nucleation position on the substrate surface.Corrosion is preferably removed at least one atomic shell equably to guarantee high-purity surface of low defective from substrate 24 surfaces.Typical corrosion is the H that contains 3-4%HCl gas approximately that is about 3 liters of per minutes with flow ₂Gas carried out under 1350 ℃ of temperature about 25 minutes.In the corrosion process, the concentration range of HCl gas is 1-5% preferably before growth.Lower HCl gas concentration might not can be removed all contaminations and surface imperfection up hill and dale from substrate.Higher HCl gas concentration may produce coarse surface topography or pit on substrate, this may cause the transverse growth of epitaxial film and produce unordered nucleation site on the entire substrate surface.Temperature in the corrosion process is 1200-1500 ℃ of scope.Lower temperature can not eliminated undesirable heterogeneous nucleation position up hill and dale.The temperature that is higher than 1500 ℃ is too fast and introduce undesirable heterogeneous nucleation position on substrate surface to the corrosion of substrate surface at the periphery of substrate.Before the growing crystal epitaxial film, can also use other growth pre-treatment such as oxidation or reactive ion etching further to remove the undesirable nucleation site of potential.

Referring now to Fig. 3, the nucleation site 70 on the substrate 24 can form heterogeneous nucleation intentionally.Nucleation site 70 can form by means of having a mind to the local surface that changes substrate 24.By in the predetermined position with diamond scriber (scribe) to substrate 24 indentations, destroying substrate and/or inject certain required many types of monocrystalline on substrate 24 in the starting the arc between the surface with acusector must (whisker), can form these positions 70.As shown in Figure 8, if will grow the 3C-SiC crystal on 6H-SiC substrate 24, shown in Fig. 3 and 7, just the many types of crystal palpus of 3C-SiC is injected at nucleation site 70 places in the required vitellarium 60 of substrate 24.For the SiC epitaxial film of growing, the optimum position of nucleation position 70 is place, 62 angle and at the platform or step 72 places at top, as shown in Figure 3 in the vitellarium.Shown in Fig. 3 and 7, the surface of substrate 24 comprises several crystal layer steps 72.When substrate is cut with any angle non-vanishing with respect to base plane, just form multiple step 72.For example, as shown in Figure 4, with respect to ° angle, base plane tilt alpha=3, substrate surface will be cut several crystal layers to form multiple crystal layer step 72 as if substrate surface.Nucleation site 70 should be positioned on the step of going up most 72, as shown in Figure 3.As shown in Figure 3, the optimum orientation of substrate tilting is 60 diagonal lines D along the vitellarium.

Substrate 24 is used for growing crystal once pre-treatment with regard to ready reaction chamber 22.Reaction chamber 22 is preferably found time by vacuum pipe V and is used the rare gas element purge with removal of contamination subsequently.H ₂Gas can be used for the purge reaction chamber.In case the reaction chamber purge is good, just make carrier gas flux and temperature in the reaction chamber reach balance.The most handy H ₂Gas is as carrier gas, but also available other gas (for example rare gas element).In a single day air temperature and current in the reaction chamber reaches balance, in 1 minute, just silane and propane is added carrier gas with beginning SiC growth usually.Silane concentration in the carrier gas preferably is about 200ppm, obtains the Si atomic percent of 200ppm thus.The propane quantity of introducing carrier gas is about 130ppm-600ppm, and the atomic percent that obtains C thus is between 390ppm-1800ppm.The aforementioned pre-treatment of substrate 24 allows departing from can depart from by the low defective SiC crystalline of growing high-quality greater than original imagination significantly best Si/C ratio.Can change Si to the atomic percent ratio of C to obtain the SiC epitaxial film of different growth velocitys and dissimilar (they being n or p type).The scope of ratio can be 0.01-1.0, preferably between 0.1-0.5.

Referring now to Fig. 4, show the atomic scale sectional view of 6H-SiC substrate 24, it comprises which floor 6H-SiC film 41 and the several extension 6H-SiC thin film layers 40 that are deposited on the substrate surface.The SiC outer layer growth speed that obtains from the carrier gas that contains 200ppm silane and 600ppm propane causes the vertical epitaxial layer-growth rate that is parallel to the C axle that per hour is about 5.5 μ m.Crystal is Once you begin grown, and multilayer 40 will be formed on mutual top, thereby obtains multilayer SiC epitaxial film as shown in Figure 4.

Fig. 7 and 8 shows the growth of 3C-SiC epitaxial film 40a on the substrate 24 that 6H-SiC epitaxial film 41 is formed.When crystal growth continued, 3C-SiC epitaxial film 40a covered the vitellarium from 3C-SiC nucleation site 70a transverse growth fully until 3C-SiC epitaxial film (thin film layer) 40a.The growth of thin film layer 40a on 6H-SiC thin film layer 40 of 3C-SiC border is called epitaxially deposited layer.Epitaxially deposited layer is a kind of epitaxial thin-film layer, and its material and many types of being different from grow its that one deck below it, or grow its that layer crystal lattice mismatch below it.Because along the planar compression between the many types of epitaxial film of two differences or uphold, epitaxially deposited layer is under the stress.Though between two many types of epitaxial films stress is arranged, because the nucleation of 3C-SiC epitaxial film occurs on the position, so, also have only seldom DPB and stacking fault even the 3C-SiC thin film layer has.

Referring now to Fig. 9, in SiC outer layer growth process, the Si atomic deposition is in Si position 82, and the C atomic deposition is in C position 80.Consequently, the SiC epitaxial film is made up of the layer that is formed on Si atom 86 on the substrate 24 and C atom 84.An epitaxial film is two stacked layers that thin film layer is represented as a Si atomic shell 86 and C atomic shell 84.The SiC outer layer growth becomes the alternately stacked layers of Si layer 86 and C layer 84, and this has just increased SiC crystalline thickness.The type that is grown in the SiC epitaxial film on the substrate can be controlled with the many types of of nucleation site and/or substrate.As shown in Figure 4,6H-SiC epitaxial film 40 is grown on the many types of substrate 24 of 6H-SiC, and this is called as isoepitaxial growth.As shown in Figure 8,3C-SiC epitaxial film 40a utilizes 3C-SiC nucleation site 70a and is grown on the many types of substrate of 6H-SiC, Here it is heteroepitaxial growth.

Fig. 9 is formed in the Si atomic shell 86 on the substrate 24 and the atomic scale synoptic diagram of C atomic shell 84.Prepared Si face 50 for the SiC outer layer growth, caused being formed on the substrate surface as the C atomic shell of first atomic shell.The growth of C atomic shell 84 causes the SiC epitaxial film that growth quality is the highest, defective is minimum on the Si face 50.In the process of growth of SiC thin film layer, at the film surface place or a large amount of dissimilar atom or molecules are arranged near it.H ₂Represent the carrier gas in the reaction chamber.C _YAnd Si _YRepresentative is decomposed out and just is being deposited on their the C positions separately or the C atom and the Si atom of Si position from their original chemical respectively.X, Y and Z representative is had a mind to or by mistake is present in impurity in the reaction chamber.Specifically, X represents same Si _XThe doping agent of (Si atom) contention Si position 82, and Y represents same C _YThe doping agent of (C atom) contention C position 80.Z is contamination that be not eliminated or that by mistake enter into reaction chamber in the reaction chamber purge process.Z may fight for C position 80, Si position 82,80 and 82 2 kind of position or two kinds of positions are not fought for.

In SiC thin film layer process of growth, the quantity and the type of the impurity that enters thin film layer are controlled to obtain having the SiC crystal of special properties.Can mix doping agent wittingly to change SiC crystalline electricity and/or optical characteristics.Phosphorus and nitrogen dopant the SiC thin film layer can be mixed for making n type layer, and aluminium and boron the SiC thin film layer can be mixed in order to make P type layer.When making n type SiC epitaxial film, phosphorus or nitrogen in the forming process of C atomic shell 84 the same C represented as Y among Fig. 9 _YContention C position 80.Equally, represented as X among Fig. 9 P type doping agent same Si in the forming process of Si atomic shell 86 such as aluminium and boron _XContention Si position 82.Impurity is subjected to the very big influence of the Si/C ratio in the reaction chamber to entering of each atomic shell.In the process of growing P-type rete (wherein aluminium, sodium, iron, gallium, titanium, vanadium or boron enter Si atomic shell 86), the quantity of the P type doping agent that enters reduces and increases with Si/C ratio in the reaction chamber.Otherwise the quantity that enters the P type doping agent of Si atomic shell 86 reduces with the increase of Si/C ratio in the reaction chamber.Equally, when growth n tunic layer (wherein oxygen or nitrogen enter C atomic shell 84), the quantity of the n type doping agent that enters increases with the Si/C ratio, and n type doping agent mixes reducing and reduce with the Si/C ratio.The inventor is definite, mixes for the n type, and fluorine, chlorine, sulphur and nitrogen enter the Si position; And oxygen and nitrogen enter the C position.Mix for the P type, sodium, iron, aluminium, gallium, titanium, vanadium and boron enter the Si position, and boron enters the C position.

It is an advantage that competition extension in position enters for the doping agent of control such as P type and n type doped epitaxial layer, and it has caused the doping scope to increase and improved the doping repeatability of chemical vapour deposition (CVD) SiC outer layer growth.Adopt position competition extension will cause device performance to improve, comprise ohmic contact and high temperature JFET under high-voltage diode, the deposit state.The purposes of position competition extension depends on Si atom in the main Si position that substitutes growth SiC epitaxial film or each specific dopant atom of the C atom in the alternative C position.Partly since when growth Si face Al substitute Si in the Si position and N mainly substitutes the C in the C position of SiC lattice, position competition extension successfully is used for controlling Al and N doping.Silicon in the growth reactor to carbon (Si/C) ratio influence consumingly that the doping agent that is grown in the epitaxial film on (0001) 6H-SiC silicon face (Si face) enters, on SiC (1210) the A face substrate and on 3C-SiC (111) and 4H-SiC (0001) the Si face base plane substrate and the doping agent of the SiC epitaxial film on SiC (0001) the C face substrate enter.

Position competition epitaxy technique is based on following discovery, and the SiC crystalline concentration of dopant that promptly enters into growth is very responsive to the ratio of Si source/C source gas.That is the concentration that enters into the doping agent of growth SiC crystal only just can controllably change by the method that each the selected quantity to the reaction chamber dopant source on purpose changes the Si/C ratio.Adopt position competition extension to produce and comprise that carrier concentration is P＞5 * 10 ¹⁸Cm ^-3The very high P type SiC single crystal film of quality.In fact obtained at least up to P＞5 * 10 ¹⁸Cm ^-3Concentration.By means of reducing Si source/C source ratio, position competition epitaxy technique provides bigger the entering of the P type doping agent of Al and so on.This causes: (1) reduces for the quantity with the Si source of P type doping agent contention available Si position, and the quantity that (2) are used to increase the available Si position that P type doping agent enters increases (promptly from available Si position increase obtain) to the ratio of C position.Adopt any prior art (wherein having adopted fixed Si/C ratio), thereby because to be held the relative populations of constant Si position also constant in Si source/C source, thereby will to reach this effect be impossible.Similarly, adopt position competition extension can obtain the much lower film of doping content.For example, by means of improving Si source/C source ratio, thereby the quantity that reduces the relative populations of available Si position and increase the Si source simultaneously can reduce the doped level of Al to get rid of the contention (the two all helps getting rid of Al from growth SiC film) of Al dopant source to available Si position.Adopt position competition extension also to obtain the adulterated superior doping scope of n type and comprise that with growth carrier concentration is n＞2 * 10 ¹⁹Cm ^-3Monocrystal thin films.Obtained at least up to about n＞5 * 10 ²⁰Cm ^-3N type concentration.In addition, the Si/C ratio can change and/or be chosen to be a ratio so that form less than 1 * 10 in monocrystal thin films ¹⁶Cm ^-3P type and n type low doping concentration, and can repeatedly obtain low reaching less than about 8 * 10 ¹³Cm ^-3Dopant level.These high dopant (promptly＞5 * 10 ¹⁸Cm ^-3) and dopant concentration (promptly＜2 * 10 ¹⁶Cm ^-3) before in the monocrystal thin films that growth obtains, can not reach.High doping content can only lean on further crystal processing (promptly ion implantation) to reach in the past.But the crystal processing of this growth back destroys or damages crystal and can not get uniform dopant distribution in crystal.

Though the inventor does not plan to propose the theory of this physical phenomenon, controlled the entering of believing doping agent in the SiC rete is that control by to the position competition at C position 80 and 82 places, Si position is realized.Concentration of dopant in the thin film layer can be controlled slightly though enter the quantity of the doping agent of reaction chamber by means of adjusting, only low-down concentration of dopant, high degeneracy concentration of dopant, precipitous pn knot or np knot and/or doping content repeatably can not be obtained by regulating concentration of dopant.By means of the demand of Si position 82 or C position 80 place's specific dopant in the control thin film layer process of growth, can carry out extra control to entering of doping agent.In the process of growth of each SiC rete, the atom of the rate dependent that forms 84 layers in Si atom 86 and C atom specific position in can filling 84 layers in Si atom 86 or C atom and/or the obtaining degree of molecule.When the concentration of the C atom in the reaction chamber increases with respect to the concentration of Si atom, because available C atomic quantity increased, to the slump in demand of the atom of inserting C position 80.Consequently, C atomic shell 84 forms with faster rate, and C position 80 is disproportionately filled by the C atom.But the relative increase of C atom influence can be used to fill the relative minimizing of the Si atom of Si position 82.The relative minimizing of available Si atom causes filling more slowly of Si position 82 and to the atom of any kind of filling Si position 82 or the bigger demand of molecule.Bigger Si locational requirement causes fills the increase of Si position 82 with the non-Siliciumatom (being doping agent, contamination) of formation Si atomic shell 86.Otherwise Si atom pairs C atom increases atom or molecule slump in demand and atom that makes 80 places, C position or the molecule increase in demand that makes 82 places, silicon position relatively in the reaction chamber.Because the relative increase of obtainable Si atom, 82 slumps in demand of Si position cause disproportionately high the occupying of Si atom in the Si atomic shell 86.And the rising of C position 80 demands makes the speed that forms C atomic shell 84 reduce and improve the quantity of impurity with respect to the C atom that enters C atomic shell 84.

When the multiple growth position of crystal is carried out control, can be used to control the crystalline Impurity Distribution and no matter reaction chamber in contained impurity.For example, in growth SiC crystalline process, even the n type and the p type doping agent of equivalent are arranged in reaction chamber, also can the growing n-type crystal.By means of the Si/C ratio of controlling rightly in the reaction chamber (promptly increasing the Si/C ratio), demand control when having realized Si position 82 and C position 80, thus reduce the demand of Si position 82 and improved the demand of C position 80.It is bigger than the amount that P type doping agent enters Si atomic shell 86 that the raising of C position 80 demands makes n type doping agent enter C atomic shell 84, thereby form n type SiC crystal.Growth position control simultaneously may be used to other crystal that growth has at least two kinds of growth positions.

The phenomenon that control impurity enters is also believed the influence of the growth velocity that is subjected to growth position physical properties, geometry of position shape and Si atomic shell 86 and C atomic shell 84.Supposed that the contention to C position 80 helps the C atom between C atom and the impurity, and the contention to Si position 82 helps the Si atom between Si atom and the impurity.In crystalline network, the particular geometric shapes that specific growth position has an atom or molecule to key in.For example, in Si position 82, geometrical shape is the shape of Si atom.Electronic cloud around the Si atom with around the atom of Si position 82 one by one bonding to form high stability key.Do not have the impurity of the suitable geometrical shape of suitable Si position 82, the probability of its bonding is very low.Si position 82 also has a specific electric charge that is caused by the atom that is positioned at around the Si position 82, and it is easy to admit the Si atom or has another kind of atom or molecule similar in appearance to the Si atomic charge.And, specific atoms to the bonding of Si position 82 and free between have a balanced reaction.It is believed that in quickish Si atomic layer growth process (Si/C ratio wherein is very big) that the balance of reaction helps the Si atom.In addition, it is believed that when the growth velocity of Si atomic shell reduced, molecular balance reduced the favourable degree of Si atom.Therefore, arrive simultaneously under the situation of Si position 82 at Si atom and impurity, the Si atom has bigger probability with Si position 82 bondings owing to its geometrical shape, electric charge with Si position 82 molecular balances.The competition of the hypothesis of Si atom in the Si position 82 be can be used for C atom competition in the C atom site 80 equally.

Control to Si/C ratio in the reaction chamber makes it possible to produce high-quality repeatably SiC crystal, can be doped to above 1.0 * 10 by degeneracy ¹⁹Cm ^-3Concentration of dopant or lowly at least reach 8.0 * 10 ¹³Cm ^-3Very light doping content.

Figure 10 shows n-p type SiC crystalline dopant distribution.At the beginning, with n type doping agent the SiC crystal doping is surpassed 1.0 * 10 to obtain several n type concentration of dopant ¹⁹Cm ^-3Degeneracy n type rete 90.The degeneracy layer is usually as the tie point (ohmic contact) between crystal and the metal connection.Dopant distribution shows SiC crystalline film 92, and it contains by dopant atom in the reaction chamber and reduces and/or Si/C concentration reduces the caused n type doping agent quantity that has reduced.94 show a precipitous np knot.

Enter the n type doping agent air-flow of reaction chamber and, can make knot 94 by means of reduction or shutoff to reaction chamber introducing or increase P type doping agent.And the Si/C concentration rate in the conditioned reaction chamber can be produced highly determine controlled and np knot repeatably.By means of improving concentration of dopant and/or reducing the Si/C concentration rate, the P type doping agent that has improved in the rete 96 enters.Doping agent enters and is enhanced until having made P type degeneracy rete 98.Also can make n type rete then and make the pn knot by means of the making P of elder generation type rete.

Figure 11 shows a SiC crystal, it have be grown in substrate 24 lip-deep P type SiC layers 100, be grown in layer on 100 n type layer 102 and be grown in P type layer 104 on the layer 102, to form pnp SiC crystal, this is the basic boom of all electron devices.Can make many different SiC crystal with method of the present invention with various dopant distribution.By means of by control in the reaction chamber Si/C concentration and growth position is controlled, can form before can not be getable controlled and repeatably be lower than 1.0 * 10 ¹⁶Cm ^-3Concentration of dopant and surpass 1.0 * 10 ¹⁹Cm ^-3Degeneracy rete (obtaining " deposit ohm " metallic contact).The SiC rete can be grown on very little or the non-existent or very big substrate surface in pitch angle.Utilize to change in the reaction chamber Si/C concentration and come the competition of control growing position, it seems the influence that is not subjected to the substrate surface pitch angle (in rational limit).But found the many types of and crystal mass of SiC crystalline that pitch angle influence growth obtains.

Crystalline purity with the growth of CVD technology can be by means of the position competition of control SiC rete particular growth position by basic controlling.In crystal growing process, the contamination shown in Z among Fig. 9 can be advanced into the SiC crystal in the growth certainly.Use H ₂And so on high gas purge reaction chamber, can reduce some but not be contamination in the total overall reaction chamber.The contamination source can be the original chemical of crystal atoms, leak and/or be incorporated into before impurity in the reaction chamber and/or the crystal growth just atom in reaction chamber or molecule unintentionally.The original chemical of crystal composition preferably selects those not to be rendered as the contamination source.Common contamination in the SiC crystal growth is an aluminium.Aluminium is often used as P type doping agent.Aluminium one enters reaction chamber, just tends to still stay in the growth room after the doping end of processing owing to its metallicity.In the pure SiC crystalline process of growth, stay aluminium in the growth room and can be bonded in the Si position 82 and reduce SiC crystalline electrology characteristic potentially.By means of improving the Si/C concentration rate in the reaction chamber and reducing the demand of Si growth position, can reduce obviously that aluminium stains the quantity that enters in the SiC crystal.By means of the growth position of determining to enter into the main contamination of SiC crystal and staiing institute's bonding, can control with the method for the contamination demand at reduction growth position place with crystal growth compound concentration ratio in the suitable conditioned reaction chamber and stain reducing of entering in the SiC crystal.

Method of the present invention can be used to make multiple semiconductor device structure.Adulterated control techniques is superior to any known conventional doping techniques of growth SiC crystalline far away.Present technique the in-situ doped abrupt change in the crystal growing process also is provided and can fully utilize from degeneracy P type (to " deposit ohm " contact) to nearly intrinsic (extremely low-doped n type or P type) until and comprise the doping content scope of degeneracy n type SiC.In the manufacturing of most of SiC devices, with this foreseeable and repeatably mode to come the ability of controlled doping agent be very crucial.The inventive method has many corrections, and for example, method of the present invention can be carried out in ultra-high vacuum system (for example molecular beam epitaxy (MBE) system).Example 1

Make a content with the CVD method of having improved and be about 1.0 * 10 ¹⁵Cm ^-3N type SiC crystal.The commercially available 6H-SiC substrate that cuts out from the 6H-SiC blank is used to this routine described method.On substrate surface, cut out the border with the Si face (0001) of diamond paste polished substrate and with the 25mm slitting saw.Subsequently substrate is placed reaction chamber and be about the H of containing of 3L/min of about 3%-4%HCl gas with flow velocity ₂Corrosion in about 20 minutes is carried out in carrier gas under 1375 ℃ of temperature.After 25 minutes, turn-off the HCl air-flow and the temperature of reaction chamber is risen to 1450 ℃ and reached balance after about 30 seconds.Silane and propane are added on reaction chamber with beginning SiC growth.200ppm silane (Si=200ppm) and 600ppm propane (C=1800ppm) are added into H ₂Carrier gas is to obtain in the reaction chamber 1: 9 Si/C ratio.N type doping agent N ₂Be added into H with 40ppm (N=80ppm) ₂Carrier gas enters with the doping agent in the beginning SiC crystal.Obtained the per hour growth velocity of 5.5 μ m with the CVD method of having improved.After about one hour, turn-off H ₂Silane in the carrier gas, N ₂With flows of propane gas and make carrier gas in the process of cooling of reaction chamber, continue in reaction chamber, to flow through about 10 minutes.Example 2

This method and example 1 are basic identical, and the content of having grown is about 6.0 * 10 ¹⁵Cm ^-3N type SiC crystal.Propane is added into H with 350ppm (C=1050ppm) to silane with 200ppm (Si=200ppm) ₂Carrier gas is to obtain 1: 5.25 Si/C ratio.N type doping agent N ₂Be added into H with 66ppm (N=132ppm) ₂Carrier gas is so that to the SiC crystal doping.Example 3

This method and example 1 are basic identical, and the content of having grown is about 3.0 * 10 ¹⁶Cm ^-3P type SiC crystal.Propane is added into H with 350ppm (C=1050ppm) to silane with 200ppm (Si=200ppm) ₂Carrier gas is to obtain 1: 5.25 Si/C ratio.P type doping agent triethyl aluminum (TMA) is by means of H ₂Bubbling in liquid TMA (keeping 21 ℃) and add H ₂Carrier gas makes 10sccm (standard cubic centimeter) introduce reaction chamber with the doped SIC crystal.Example 4

This method is with basic identical with example 1, and the content that is used as ohmic contact of having grown is about 2.0 * 10 ¹⁹Cm ^-3Degeneracy P type SiC crystal.Propane adds H with 600ppm (C=1800ppm) to silane with 200ppm (Si=200ppm) ₂Carrier gas is to obtain 1: 9 Si/C ratio.P type doping agent TMA is added into H with 21sccm ₂Carrier gas is with the doped SIC crystal.Before the cooling reaction chamber about 5 minutes the time, turn-off the silane air-flow and continue to flow through H ₂, propane and TMA air-flow.Example 5

This method and example 1 are basic identical, and the content that is used as ohmic contact of having grown is about 2.0 * 10 ¹⁹Cm ^-3Degeneracy n type SiC crystal.Propane is added into H with 130ppm (C=390ppm) to silane with 200ppm (Si=200ppm) ₂Carrier gas is to obtain 1: 1.95 Si/C ratio.N type doping agent N ₂Be added into H with 1153ppm (N=2306ppm) ₂Carrier gas is with the doped SIC crystal.Before the cooling reaction chamber about 5 minutes the time, turn-off flows of propane gas and continue H ₂, silane and N ₂Air-flow.Example 6

This method and example 1 are basic identical, have grown to contain the multiple many types of SiC crystal of a p/n knot.6H-SiC substrate 3C-SiC crystal nucleation.The pitch angle of substrate is 0.2-0.3 °.Crystal growth begins until 3C-SiC crystal fan widens to the whole growth district.In the initial growth process of 3C-SiC, carry out example 5 described degeneracy n types and mix.After the degeneracy n type SiC epitaxial film, with the example 2 epitaxial films light dope n type epitaxial film of growing basic identically.By means of finishing n type epitaxial film and, making the pn knot as the degeneracy P type epitaxial film that begins to grow as described in the example 4.The position distribution of the relative 6H-SiC epitaxial film of 3C-SiC epitaxial film table top table top is at random on the substrate, and the per-cent of 3C-SiC table top is about 50%.Adopt and determine 7 * 10 ^-6Cm ²-4 * 10 ^-4Cm ²The aluminium etching mask that 2000 dusts of the circle of areal extent and square diode table top are thick is also graphical with peeling off method.Under 250 milli torr growth room pressure,, use 80%SF in 300Wrf ₆: 20%O ₂Reactive ion etching (RIE) make the be corroded degree of depth of about 10 μ m of diode table top.Peel off the aluminium etching mask with warm caustic solution, immerse in the sulfuric acid that boils then and clean.Under 1150 ℃, sample is carried out wet oxidation 6 hours to form the thick SiO of at least 500 dusts ₂After wafer has been made the figure that is used to contact, with 6: 1 towards rare HF solution corrosion zone of oxidation, form through hole.Electron beam deposition aluminium and peeling off then to finish element manufacturing.The 3C diode presents rectification characteristic to the 200V reversed bias under 25 ℃ of room temperatures, on behalf of 3C-SiC diode voltage disposing capacity, this improved 4 times.When the electric current that flows through in the reverse breakdown process was restricted to less than 1mA, puncture was repeatably (be curve can keep the extremely long time and do not change device property); Unconfined electric current causes the permanent damage of device.On the device of testing on the substrate, only around device boundaries, observe the corona of microplasma during puncture, edge rather than because mechanism body that this explanation was oppositely lost efficacy and occurred in table top.Overcurrent when diode is in a single day breakdown damages dissolvingly, and may to be device just replace along the single microplasma of the breaking-up point of mesa edge multiple microplasma corona.Figure 12 shows logarithmic scale forward and the reversible circulation voltage characteristic under the several temperature.Though the nature that improves of reverse leakage depends on voltage and the temperature that is elected to be benchmark, the improvement that these 3C-SiC diodes show the reverse leakage flow density of at least one order of magnitude significantly with respect to any 3C-SiC pn diode of previous distribution.Because reversible circulation is not proportional to the square root of impressed voltage, so can infer that the mechanism outside some thermal excitation is the reason of reverse leakage.The exponential region of forward characteristic presents the low saturation current density in ground that sets a record of CVD growth 3C pn diode.But theoretical factor is failed fine understanding so far with the change of temperature.

Go up routine described method and show the controlled and repeatably doping of SiC crystalline, it has level and smooth surface topography and low defect concentration.The CVD method of improved may be used to the crystal that has two kinds of growth positions at least beyond the growth SiC, and controls its purity and dopant profiles, even this crystalline chemical property, growth parameter(s), doping agent and contamination etc. are different from the SiC crystal.A kind of crystal that the method for having improved might be used is the GaAs crystal.It is controllable doped to estimate respectively that below example shows gallium arsenide (GaAs) crystalline.Example 7

To this routine described method, make the content that is used for ohmic contact and be at least 1.0 * 10 ¹⁹Cm ^-3Degeneracy P type GaAs crystal.The GaAs substrate is polished, cuts out the growth border and corrosion surface before growing crystal on the substrate.Reaction chamber is raised to suitable crystal growth temperature and makes carrier gas stream balance in the reaction chamber.Make the compound and the carrier gas that contain Ga and As make up crystal growth with beginning GaAs.Situation for the P type doping agent of preferential contention Ga position will reduce with respect to As concentration Ga concentration, and this has improved the demand of Ga growth position and thereby has increased entering of P type in the GaAs crystal.The quantity of introducing the P type doping agent of reaction chamber should be GaAs epi-layer surface pattern not to be played the maximum quantity that detrimentally affect allows.Before reaction chamber cooling 5 minutes the time, turn-off the Ga compound that flows into reaction chamber and continue to circulate P type doping agent, arsenic compound and carrier gas.Example 8

This method and example 7 are basic identical, and the content of growing is at least 1.0 * 10 ¹⁹Cm ^-3Degeneracy n type GaAs crystal.For the situation of the n type doping agent of preferential contention As position, Ga concentration is enhanced to improve the As locational requirement and to increase entering of n type doping agent in the GaAs crystal with respect to As concentration.The quantity of waiting to introduce the n type doping agent of reaction chamber should be GaAs crystalline surface topography not to be played the maximum quantity that undesirable action allows.The reaction chamber cooling should be turn-offed the As compound that flows into reaction chamber in the time of 5 minutes before, and continues the air-flow of n type doping agent, Ga and carrier gas.Example 9

This method and example 7 are basic identical, and the content of growing is much smaller than 1.0 * 10 ¹⁹Cm ^-3P type GaAs crystal.Ga concentration is enhanced with respect to As concentration so that obtain sizable Ga/As ratio (with respect to the Ga/As ratio of example 7) in the growth room.P type doping agent with appropriate quantity adds reaction chamber then.Example 10

This method and example 8 are basic identical, and the content of growing is much smaller than 1.0 * 10 ¹⁹Cm ^-3N type GaAs crystal.Ga concentration in the reaction chamber will reduce with respect to As concentration, so that obtain quite little Ga/As ratio (with respect to the Ga/As ratio of example 8).N type doping agent with appropriate quantity adds reaction chamber then.Example 11

From (0001) towards 3 ° of (1210) face off-axis and the polishing commercially available n type Si face SiC substrate on, the SiC epitaxial film of under 1450 ℃, having grown.The SiC substrate places on the graphite bearing that is coated with Si-C and is loaded into the water-cooled quartz reactor of atmospheric pressure cvd system.Use H ₂Silane (H in the carrier gas ₂In contain 3%) and propane (H ₂In contain 3%) the SiC epitaxial film of growing, obtain～growth velocity of 3 μ m/h, and use N ₂(for the n type) or triethyl aluminum (TMA is for the P type) mix.Test the epitaxial film characteristic with second ion mass spectroscopy (SIMS) analysis, mercury probe or pn diode capacitance voltage (C-V), low temperature photoluminescence spectrum (LTPL) and hall mobility measurement.Used competition extension in position by means of the Si/C ratio of regulating in the growth reactor to control the quantity (doping agent control techniques) of the doping agent that enters SiC lattice alternative site effectively.Be positioned at these positions on effective growth surface of carborundum crystals, promptly carbon crystallographic site (C position) or silicon crystal lattice position (Si position) are controlled by position competition extension.The model of position competition extension is based on the principle of contention Si position between the C position of the SiC layer in the contention growth between nitrogen and the carbon and aluminium and the silicon.Make C surpass N and fight for the C position by means of improving C source concentration, reduced the concentration of n type (nitrogen) dopant atom that enters SiC epitaxial film in the growth.Equally, make Si surpass Al and fight for the Si position, reduced the quantity of the P type doping agent (aluminium) that enters by means of improving silicon source concentration in the growth reactor.By means of changing propane concentration, keep constant silane and dopant source concentration simultaneously, a series of P types of having grown and the adulterated monocrystalline of n type to change the Si/C ratio effectively.Mix for crystalline P type, when keeping constant silane air-flow (200 atom ppm) and TMA air-flow (2sccm H ₂Air communication is crossed the TMA bubbler under the constant room temperature) time, propane concentration is unique variable (400-000at.ppm) parameter that changes Si/C ratio in the growth reactor effectively.The P type doping (from the raising of Si/C ratio) that presents relative rising in silicon concentration causes the SiC epitaxial film discharge of aluminium from growth.Having found to adopt 0.1 Si/C ratio to obtain clean carrier concentration is P＞1 * 10 ¹⁹Cm ^-3Degeneracy doping P type epitaxial film.With the SiC crystal that 0.5 Si/C ratio has been grown other, obtaining clean carrier concentration is P=5 * 10 ¹⁶Cm ^-3P type epitaxial film.Find, when the Si/C ratio when 0.1 brings up to 0.5, the relative populations of Si increase and the SiC lattice that aluminium can't be fought for growing in available Si position, the decline that this finally causes the Al doping agent to enter.

In the process of growing n-type doped epitaxial layer, it is constant that silane (200ppm) and dinitrogen (90ppm) concentration keep, and propane concentration changes between 133-600ppm.Tested the nitrogen dopant distribution with SIMS and mercury probe C-V.The variation of the Nitrogen Atom concentration in the epitaxial film that the open-birth of SIMS distribution table is looked only changes from Si/C ratio (between 0.5-0.1) in the epitaxial process.The clean carrier concentration profile that obtains from the mercury probe C-V of same sample distributes with SIMS and meets finely.The result shows, the doping agent that position competition extension has been controlled in the electroactive crystal position of the SiC epitaxial film of growing enters.

In order to confirm the repeatability of position competition extension, two extreme (0.1 and 0.5) with the Si/C ratio keep constant Si (200 atom ppm) and N (100 atom ppm) concentration, a large amount of crystal of having grown simultaneously.Adopt Si/C=0.1, it is n ≈ 3 * 10 that the crystal of growth obtains clean carrier concentration all the time ¹⁵Cm ^-3The n type have a mind to doped epitaxial layer.And, adopting Si/C=0.5, the crystal that growth obtains is always n ≈ 3 * 10 ¹⁷Cm ^-3N type epitaxial film.Believe carbon with respect to the reduction of silicon concentration (from the raising of Si/C ratio from 0.1 to 0.5) allow nitrogen that carbon is discharged contention to the C position of the SiC lattice the growth, the increase that causes Nitrogen Atom to enter.

Utilize competition extension in position to be not intended to foreign atom eliminating from the entering of growth SiC epitaxial film in the growth reactor, produced very low-doped epitaxial film.Carried out detecting relative concentration with LTPL spectrum to be not intended to doped epitaxial layer with these of Si/C=0.1 growth with the doping agent of determining to enter in perfection of lattice and the process of growth.LTPL result from our minimum doped p type epitaxial film unintentionally obtains draws I ₇₇/ P ₀=150 and I ₇₇/ S ₀=4.7, show the SiC of the intrinsic that is hitherto reported.For low-doped SiC, the same I of the concentration of dopant among the SiC ₇₇/ P ₀And I ₇₇/ S ₀Ratio of peak (peak-height ratio) connects, wherein P ₀And S ₀Be respectively the non-phonon line strength of nitrogen alms giver (nitrogen donor no phonon line intensity) at 3.00eV and 2.99eV place, and I ₇₇It is the peak strength of the imitative type of the SiC77-meV of 2.947eV place intrinsic phonon.Adopt these ratios, obtained being estimated as 1 * 10 with LTPL ¹⁴Cm ^-3Be not intended to concentration of dopant, P＜5 * 10 that this obtains with mercury probe C-V indoor temperature measurement ¹⁴Cm ^-3Be consistent.Position competition extension is used as the doping agent of producing low-doped SiC epitaxial film and gets rid of growing technology.Equally, impel in the SiC outer layer growth process dopant atom to strengthen with position competition extension and enter, produced the degeneracy doped epitaxial layer.Be used in during last 30-40 second of outer layer growth and the method for in the substrate process of cooling, turn-offing Si or C source air-flow, made very thin degeneracy doped p type and n type contact layer.This make dopant atom can enter the p type of growing at top or n type epitaxial film respectively and needn't with Si or the competition of C atom.Be used in outer layer growth all the other 30-40 second during only turn-off the method that flows of propane gas keeps silane (200 atom ppm) and nitrogen (300 atom ppm) air-flow simultaneously, made degeneracy n type epitaxial film.

The metallic contact that is deposited on p type and the n type degeneracy epitaxial film is " deposit ohm " (promptly unannealed) that comprises a large amount of metals of aluminium, titanium, nickel and molybdenum.The deposit molybdenum on n type and the p type degeneracy doped epitaxial layer and the contact resistivity of titanium (linear transfer line method (TLM)) as calculated are respectively pb＜5 * 10 ^-5Ω cm ²And pc＜2 * 10 ^-5Ω cm ²Degeneracy Doped n-type contact epitaxial film n=4 * 10 have at room temperature been recorded ¹⁸Cm ^-3Low free carrier concentration and obtain near 60cm ²The mobility of/Vs.When considering incomplete ionization, n=4 * 10 ¹⁸Cm ^-3Low free carrier concentration convert to above N in theory _D=2 * 10 ¹⁹Cm ^-3Nitrogen Atom concentration.The higher electric field (with respect to the Hall technology) that is applied by the C-V technology causes the free carrier concentration that records higher owing to the field in the market depletion region that occurs in schottky diode strengthens ionization.N=8 * 10 ¹⁶Cm ^-3The scope of room temperature hall mobility of relative more lightly doped n type epitaxial film be 247-253cm ^-2Vs, and find it is less than 10% compensation.With position competition epitaxial growth superior SiC electron device.Owing to utilized and to have made position and compete extension and make the doping scope obtain increase, so these devices demonstrate superior electric property with higher SiC device that stops voltage and lower dead resistance.The achievement that this device obtained comprises high pressure 6H-SiC diode (2000V) and 3C-SiC diode (300V), and the highest 6H and 3C-SiC that they demonstrate hitherto reported stop voltage.

Example 12

The 6H-SiC epitaxial film of on the wafer that commercially available n type (0001) SiC Si face ball cuts out, in the atmospheric pressure cvd system, having grown.With the standard degreasing solution SiC substrate is carried out precleaning, immersed boiling sulfuric acid subsequently 10 minutes, last deionized water rinsing is also used filterable nitrogen drying.The substrate that cleaned is placed on the graphite bearing that SiC applies, and uses the quartzy carrier of melting (fused) to pack in the smelting quartz reactor of water-cooled then.By the radio frequency (rf) that is coupled on the bearing sample is heated, the bearing temperature is controlled to be 1450 ℃ with opticpyrometer.Silane (H ₂In contain 3%) and propane (H ₂In contain 3%) be used as SiC outer layer growth source, and H ₂In 3% HCl gas be used to before outer layer growth in 1350 ℃ of following in-situ corrosions 4 minutes.All gas comprises the ultra-pure H that crosses with the palladium diffuser tube purifying of heating ₂Carrier gas is all controlled by mass rate.By means of in the outer layer growth process with two borine (H ₂In contain the B of 100ppm or 500ppm ₂H ₆) add reactor and epitaxial film is carried out the p type mix.

In CVD polycrystalline Si C chamber in 1700 ℃ of growth after annealings that in the ultrapure argon atmospher of normal pressure, crystal carried out 0.5 hour.Carry out second ion mass spectroscopy (SIMS) research with CAMECA IMS-4f double focusing magnetic scanning ion microanalyzer.Utilize detector under negative secondary ions detection mode respectively monitoring (H) and diatomic species B (+C) and N (+C), caesium bombards and to be used to determine hydrogen, boron and nitrogen atom concentration distribution.Determine the boron concentration of aluminium and degree of precision with oxygen bombardment and positive secondary ions detection mode.

Control the quantity of the boron that enters the 6H-SiC epitaxial film with position competition extension.Determined that first specific dopant atom occupies the C position or the Si position of SiC lattice.Reported boron occupy Si position and C position the two, this boron that may make position competition extension can not be used for effectively controlling among the SiC mixes.But the CVD experimental result is pointed out boron and is preferentially occupied the Si position of SiC lattice.Found the increase (that is Si/C ratio increase) along with silane concentration, the boron in the SiC epitaxial film enters and reduces, this be with SiC outer layer growth process in the silicon amount that increases to make boron can not capture available Si position corresponding to.On the contrary, reduce silane concentration or only increase propane concentration, the Si/C ratio is reduced, just entering of boron is increased.Mix the propane concentration change for effectively controlling boron, wherein in the outer layer growth process, keep constant silane and two borane concentration simultaneously by means of increasing propane concentration continuously, the Si/C ratio is progressively reduced.Along with the relative reduction of propane concentration owing to Si/C ratio in the growth room is increased, the boron in the epitaxial film enters increase.More available Si position on the SiC epi-layer surface that this of silicon concentration reduces to allow the boron atom that Siliciumatom can not be fought for is relatively growing causes that boron enters increase in the SiC epitaxial film.

For the repeatability of the control of determine mixing, the SiC epitaxial film of a large amount of boron-dopings of having grown of in 2 hours independent growth experiments, (respectively adopting the constant Si/C ratio in the 0.1-0.5 scope).To selected epitaxial film, the element boron concentration that SIMS determines compares with the clean carrier concentration that mercury probe C-V records.The clean carrier concentration that records with the C-V of the typical epitaxial film of Si/C=0.51 growth is p=5 * 10 ¹⁵Cm ^-3, and by contrast, be p=3.5 * 10 with the clean carrier concentration of the epitaxial film of Si/C=0.11 growth ¹⁷Cm ^-3, wherein two growing crystals all use identical pair of borane concentration (1.6ppm).More low-doped (p=5 * 10 of second ion mass spectroscopy analysis revealed ¹⁵Cm ^-3) the element boron concentration of epitaxial film be (B)=6.5 * 10 ¹⁶Cm ^-3, and higher (p=3.5 * 10 of boron-doping ¹⁷Cm ^-3) the SiC epitaxial film be (B)=1 * 10 ¹⁸Cm ^-3Show that by significantly increasing of only changing that boron that the Si/C ratio causes enters boron enters the strong dependence that employed Si/C ratio and Si position in the outer layer growth process are occupied the preferential B of C position.Then with low temperature photoluminescence spectrum (LTPL) detection with identical Si/C ratio but the SiC epitaxial film of three boron-dopings that different two borane concentration is grown.In order to eliminate the potential impact that different propane concentrations enter hydrogen, thereby isolate the hydrogen entrance effect, adopted identical Si/C ratio in only changing two borane concentration.The spectrum that obtains shows the hydrogen that contains significant amounts in the epitaxial film of each boron-doping.The quantity that directly is proportional to the boron that enters the SiC epitaxial film that enters of hydrogen is pointed out in the analysis of hydrogen in the crystal.Prepared and contained the epitaxial film that progressively increases from the boron concentration (B) that only changes the Si/C ratio and used sims analysis subsequently hydrogen.Do like this is in order to confirm that entering of hydrogen and boron is relevant and determines whether that or its optical activity has been changed simply because annealing hydrogen has been eliminated.Observe the increase of the increase of hydrogen concentration corresponding to boron concentration in the epitaxial film.This shows that entering directly of hydrogen enters relevant for the boron in the 6H-SiC epitaxial film.In argon, after 1700 ℃ of annealing half an hour, sample is determined again the SIMS depth distribution analysis of boron and hydrogen concentration.The result shows, because 1700 ℃ of annealing, hydrogen has diffused out the SiC epitaxial film.Be retained in hydrogen richness in the boron-doping epitaxial film and be lower than hydrogen background concentration (＜2 * 10 in the SIMS instrument ¹⁷Cm ^-3).Also point out boron not owing to tangible solid-state diffusion is experienced in 1700 ℃ of annealing, the precipitous proof of continuation that this has been distributed by (B).Discovery annealing before, the acceptor atom of hydrogen passivation boron-doping SiC epitaxial film.For the clean carrier concentration in annealing back is p=9 * 10 ¹⁵Cm ^-3, p=1.9 * 10 ¹⁶Cm ^-3And p=6.5 * 10 ¹⁶Cm ^-3Three samples, increase by the carrier concentration that reduces to cause of annealing back hydrogen passivation and to be about 4.5 times, 3 times and 3.25 times respectively.

Found that competition extension in position is effectively for the boron doping of control CVD6H-SiC (0001) epitaxial film, entering of boron is inversely proportional to the interior used Si/C ratio of reactor in the SiC outer layer growth process.The LTPL of boron-doping epitaxial film and sims analysis show that all hydrogen concentration contained in the epitaxial film increases with the increase that boron enters.

Example 13

The 6H-SiC epitaxial film of in the atmospheric pressure cvd system, on the wafer that commercially available n type 6H and 4H (0001) SiC Si face and C face 6H (0001) SiC blank cut out, having grown.The SiC substrate is with the pre-washing of standard degreasing solution, immerses subsequently in the ebullient sulfuric acid 10 minutes, at last with deionized water rinsing and with filterable nitrogen drying.The substrate that cleaned is placed on the graphite bearing that has applied SiC, packs in the smelting quartz reactor of water-cooled with the smelting quartz carrier then.With RF-coupled bearing sample is heated, the temperature of bearing is controlled at 1450 ℃ with opticpyrometer.Silane (gas cylinder H ₂In contain 3%) and propane (H ₂In contain 3%) be used as SiC outer layer growth source, and used Slpm H ₂The ultrapure HCl gas of 90sccm in the air-flow carried out in-situ corrosion in the time of 1350 ℃ before epitaxy is about to begin.All gas comprises the ultrapure H that crosses with the palladium diffuser tube purifying of heating ₂Carrier gas is all controlled by mass rate.In the outer layer growth process, use phosphorus (H ₂The PH of middle 200ppm ₃) or nitrogen (H ₂In 0.1% N ₂) method that adds reaction tubes carries out the n type to epitaxial film and mix, with adding two borine (H ₂The B of middle 100ppm ₂H ₆) or the method for triethyl aluminum (bubble structure) epitaxial film carried out the p type mix.Carry out second ion mass spectroscopy (SIMS) analysis with CAMECA IMS-4f double focusing magnetic scanning ion microanalysis instrument.Utilize detector under negative secondary ions detection mode, monitor respectively H-, P-and diatomic species B (+C)-, N (+C)-, the caesium bombardment is used to determine that the atomic percent of hydrogen, boron, phosphorus and nitrogen distributes.For 6H and 4H-Si (0001) Si face sample, find that the nitrogen dopant of Si face epitaxial film enters directly relevant with the Si/C ratio in the reactor.Silane and nitrogen gas stream all keep constant by means of only change flows of propane gas in the outer layer growth experimentation, on purpose change the Si/C ratio.The SIMS depth profile shows that the increase of flows of propane gas reduces during Nitrogen Atom concentration is with outer layer growth.This with the SiC epi-layer surface that nitrogen can not be fought for growing on the quantity increase of carbon of empty carbon location (C position) of SiC lattice be consistent.

Entering of phosphorus (P) doping agent is confirmed as being inversely proportional to the Si/C ratio.When flows of propane gas reduced and keeps constant silane and phosphine air-flow, SIMS determined that the p in the Si face 6H-SiC epitaxial film enters and reduces.P enters with these changes of Si/C ratio vary consistent with the p atom that occupies SiC lattice silicon position (Si position).When flows of propane gas increased, the quantity of empty Si position increased, and this may make the p in the SiC epitaxial film enter enhancing.P type on the Si face mixes and does the Al doping and two borine is done boron and mixed and realize with triethyl aluminum (TMA).Sims analysis show the Al doping agent enter with 6H and 4H Si face substrate in the outer layer growth process used Si/C ratio be inversely proportional to.SIMS determines, when the flows of propane gas in the CVD reactor increases and silane air-flow when reducing, Al enters increase, and this demonstrates Si and the Al contention to the Si position on the Si face 6H-SiC epitaxial film of growing.

Equally, the doping of discovery boron is relevant with the Si/C ratio.In boron-doping outer layer growth process, except the entering of boron, the hydrogen of concentration significant hole passivation (hole-passivating) also enters.Sims analysis shows to utilize in 1700 ℃ of argons annealed 30 minutes, hydrogen can be removed from epitaxial film, and this makes the mercury probe headroom cave concentration of these boron-doping epitaxial films improve 3 times.The p type that discovery is grown in the epitaxial film on C face 6H-SiC (0001) sample mixes similar in appearance to the resulting situation of Si face substrate.Entering of Al and B doping agent all presents similar Si/C ratio dependence on the C face.Yet, when with the isometric growth process in the Si face substrate that is doped when comparing, Al on the C face substrate and B enter all do not have so big.For the C face epitaxial film of mixing Al, the Al doping agent that SIMS determines enters approximately little 50 times than corresponding Si face epitaxial film.Equally, than the Si face epitaxial film of mixing B simultaneously; Mix the B concentration of the C face epitaxial film of B and also hang down 50 times.For the Si face epitaxial film of mixing B, the C face epitaxial film of mixing B has been detected hydrogen, wherein the definite step type B concentration distribution of the variation in the H concentration distribution determined of SIMS and SIMS is similar.

Found that the Si face position competing phase of 6H-SiC (0001) is similar to the Si face position competition of 4H-SiC (0001) substrate.The position competition obviously occupies the Si position consistency that is grown in the epitaxial film SiC lattice on Si face and C face 6H-SiC (0001) substrate to adulterated effect of Al and Al.Mix for the boron on two kinds of faces, obtained a kind of similar position competitive effect, believe that wherein B mainly occupies the Si position.Mix for the n type that carries out with phosphorus, it is very consistent that position competitive effect and p atom mainly occupy the Si position.Believe by means of under the situation of the size that compares Si or C atom, considering the occupied crystallographic site of each dopant atom, can explain this effect best.Specifically, the nonpolar covalent radius of You Xingqu element is: Si (1.17A); C (0.77A); Al (1.26A); B (0.82A); P (1.10A); N (0.74A).As first approximate (promptly ignoring the chemical bonding factor), Al and P should replace Si rather than the C in the SiC lattice with atomic size, and this is consistent with experimental result.The more approaching coupling of the atomic size of B and C, so B should mainly replace the C in the C position, this and experimental evidence are directly inconsistent.But significantly the H of quantity enters mixing in the B epitaxial film in the growth simultaneously, therefore, and soluble these results of " B-H " complex compound (complex)." B-H " particle has and the tightr matched size of Si (1.17A) (1.10A), therefore should occupy the Si position; This is consistent with experimental result.Because " B-H " particle of hypothesis has bigger effective dimensions,, replaces in the B-H complex compound so presenting the Si position.

N on the Si face mixes consistent with the position competition mechanism, and wherein quite little N atom is with C atom contention available C position.The small size of also finding N also makes N can fight for a spot of Si position.When SiC crystal growth during at the C of substrate face, this effect is the most obvious.The result who adopts position competition on the C face and N dopant atom replacement according to qualifications enter the Si position, and simultaneously N being entered the C position, to make obvious contribution be consistent.

Position competition extension is successfully used to Si face and the p type on the C face and the control of n type doping agent of 6H-SiC (0001) off-axis substrate.Doping result for the A face shows that the position competitive effect depends on SiC polarity consumingly and is subjected to many types of influence not obviously.6H is similar with the result of 4H SiC Si face sample, and 6H SiC C face sample obtains visibly different result, particularly for the adulterated epitaxial film of N.In the N doped epitaxial layer on C face and Si face in result's the comparison of growth, believe that surface tissue and the less gas phase that depends on that the position competition mechanism depends on the SiC substrate interact.Mix for the p type, on two kinds of polar surface, when the Si/C ratio descends, Al and B doping agent enter increase.Equally, when reducing the Si/C ratio wittingly, the entering also of p doping agent on Si face and the C face all increases.This is consistent with P, Al, B with Si contention available Si position.The position of finding every kind of doping agent depends on they and atomic size with respect to Si (Si position) and C (C position) according to qualifications.Herein, P and Al will enter the C position not change spacing of lattice then obviously be too big.Because the H of significant amounts combines with B, the relative dimension of B is considered to the size of " B-H " complex compound.To this situation, if change the SiC lattice dimensions not obviously, " B-H " thus the effective dimensions of complex compound greatly also is not easy suitable C position too.On the contrary, the quite little size of N dopant atom makes it can enter two kinds of crystallographic sites.Therefore, the N on the Si face mixes and causes N to enter Si position and C position, mainly is to enter the C position.On the contrary, mix for the N on the C face, N mainly enters the Si position, and the C position is had only quite little entering.Therefore, the N doping agent position competition mechanism that enters Si position and C position depends on the polarity of growth surface significantly.

Example 14

Having respectively on commercially available 6H (0001) the Si face SiC substrate at 0.2 ° of-0.6 ° and 3 °-4 ° of scope pitch angle in 1450 ℃ of grown 3C-SiC and 6H-SiC epitaxial films.The SiC substrate is placed on the graphite bearing that is coated with SiC and packs water-cooled quartz reactor CVD system into.The epitaxial film that growth obtains is determined active doping content with mercury probe or pn diode CV.The having a mind to and be not intended to doping agent of 6H, 3D that Si/C ratio in the growth reactor obtains growth and 4H SiC (0001) epitaxial film entered intense influence.Specifically, for the outer layer growth on SiC (0001) base plane, find that active n type (nitrogen) carrier concentration is proportional to the Si/C ratio, and active p type (aluminium) concentration is inversely proportional to the Si/C ratio.When the Si/C ratio in the growth reactor reduces, the active nitrogen density loss in the SiC epitaxial film that growth obtains.When the Si/C ratio further drops to Si/C ≈ 0.1, be not intended to adulterated epitaxial film and be transformed into the p type by the n type.The result has obtained p type and two kinds of epitaxial films of n type, and the room temperature carrier concentration that its mercury probe CV and low temperature light fluorescence (LTPL) record is 1 * 10 ¹⁴Cm ^-3Originally our doped epitaxial layer that is not intended to of laboratory growth all had only the n type, and its minimum clean carrier concentration generally is confined to be about n=2-3 * 10 ¹⁶Cm ^-3

Believe that the doping agent among the SiC occupies certain location, specifically, nitrogen mainly occupies the carbon location on the Si face, and aluminium occupies the silicon position of SiC lattice on crystal face two sides.The relative increase of carbon concentration makes nitrogen withdraw from contention to C position in the SiC lattice of growing.There is similar situation in Si/C ratio for having improved, and wherein the relative increase of silicon concentration makes Al withdraw from contention to Si position in the SiC lattice of growing.The nitrogen of 100ppm (50ppm N ₂) be introduced into growth reactor, by means of being dropped to Si/C ≈ 0.1 from Si/C ≈ 0.44, the Si/C ratio stop it to enter the epitaxial film of growing then.0.1 the Si/C ratio to cause obtaining all the time clean carrier concentration be n=1 * 10 ¹⁵Cm ^-3Have a mind to Doped n-type SiC epitaxial film.On the contrary, adopt the growth of the more typical Si/C=0.44 that has 100ppm N to cause n=1-2 * 10 ¹⁷Cm ^-3N type epitaxial film.For the outer layer growth that uses Si/C=0.1, the carbon amount that is increased is considered to make nitrogen to withdraw from contention to the SiC lattice C position of growing.Also made p type epitaxial film with this method.For these serial experiments, in the outer layer growth process, the TMA air-flow is introduced into reactor.The p type epitaxial film that obtains with the Si/C=0.44 growth is measured as 5 * 10 ¹⁶Cm ^-3, and the epitaxial film of growing with Si/C=0.1 is a degeneracy doped p type epitaxial film, the clean carrier concentration of its estimation is 1 * 10 ¹⁹Cm ^-3When the Si/C ratio from 0.44 when being dropped to 0.1, also reduce with the relative populations of the Si of the Si position of Al contention SiC lattice, this causes that Al enters increase.

Position competition extension also successfully is used for obtaining the very precipitous change of SiC epitaxial film concentration of dopant.In conventional CVD system, the steepness of dopant distribution is subjected to restriction that dopant source is gone out from the growth reactor purge.Adopting an advantage of the outer layer growth of position competition extension is by means of getting rid of residual undesirable doping agent with dopant source gas and changing Si/C ratio, can obtaining more precipitous dopant distribution.On the contrary, for the production of the adulterated epitaxial film of height degeneracy, can realize very precipitous enhancing doping agent enter.A very useful example of this respect is to make extremely thin degeneracy doped p type and n type contact layer by means of the source air-flow that turn-offs Si or C in during the last several minutes of outer layer growth respectively.Metals deposited contact subsequently is various metal on p type and the n type epitaxial film " deposit ohm ".The contact resistivity of deposit molybdenum calculates with linear TLM method and is P on n type and the p type degeneracy doped epitaxial layer _C＜5E-5 Ω cm ²Having a mind to have carried out preliminary Hall measurement on the adulterated 6H-SiC epitaxial film sample.Find n=8 * 10 ¹⁶Cm ^-3N type epitaxial film compensation less than 10% is arranged, the scope of its room temperature hall mobility is 247-253cm ²/ Vs.At room temperature, the mobility of heavy doping n type contact epitaxial film is near 60cm ²/ Vs, and low the free carrier concentration that records is n=4 * 10 ¹⁸Cm ^-3When considering incomplete ionization, 4 * 10 ¹⁸Cm ^-3Low free carrier concentration convert in theory and surpass 2 * 10 ¹⁹Cm ^-3Nitrogen Atom concentration." deposit ohm " state of contact can not carry out the conventional C-V distribution measuring of heavy doping epitaxial film.For minimum doped n type and p type epitaxial film, low temperature light fluorescence (LTPL) is used to determine that perfection of lattice enters with relative doping agent.Be not intended to the LTPL result that doped p type epitaxial film obtains from we minimum and cause I ₇₇/ P ₀=150 and I ₇₇/ S ₀=4.7.Concentration of dopant (1 * 10 unintentionally by the LTPL estimation ¹⁴Cm ^-3) and mercury probe CV indoor temperature measurement (p=5 * 10 ¹⁴Cm ^-3) be consistent.

SiC (0001) base plane 6H and 3C-SiC have been illustrated novel growth method, and this method is carried out based on use the Si/C ratio rightly in the outer layer growth process so that to concentration of dopant and is controlled.When the Si/C ratio when about 0.1 is changed to 0.8, carrier concentration also changes.Alms giver's carrier concentration on the epitaxial film that growth obtains is proportional to the Si/C ratio, and is subjected to main carrier concentration to be inversely proportional to the Si/C ratio.To the Si/C ratio between all 0.1-0.8, surface topography that obtains and crystal mass all are good.

Electricity device of the present invention is used and is concentrated on the favourable purposes that this growth new technology makes it to become possible wideer doping scope.Because the present invention allows to enter into compound semiconductor crystal than the higher concentration of dopant that before might accomplish, so the electric device structure that the degeneracy doping level that any its performance is subjected to reaching in any zone of device influences all can be subjected to influence of the present invention.

The CVD method of having improved has obviously reduced the contact resistance at ohmic contact place.Performance such as transistorized many semiconductor device structures all depends on contact resistance.Contact resistance is that the physical interface by metal (it passes to and spread out of semiconducter device with electrical signal with power) contact (or connection) semiconductor surface place causes.Contact resistance is as far as possible little by means of making, and the performance of most of semi-conductor electricity devices all is improved.In the electric property of a lot of devices of transistor and so on, this is a limiting factor, and it has limited the circuit that constitutes with this device and the performance of system again.Extensively recognize in order that be respectively the key constraints of many 6H-SiC or 3C-SiC device electric property the contact resistance of 6H-SiC or 3C-SiC.By means of making semi-conductor high as far as possible in the doping that itself and metal ohmic contact form the place that physics contacts, the contact resistance of semiconducter device is done as far as possible for a short time.Because the CVD method of having improved makes compound semiconductor (for example SiC) epitaxial film of device quality (being high quality) can be with higher doping content growth, so can reduce, thereby improve the performance of many electron device and circuit based on compound semiconductor to the contact resistance of these epitaxial films (thereby also being the electron device that is produced on the appropriate design in these epitaxial films).

The CVD method of having improved has also reduced the crystalline semiconductor bulk resistor that growth obtains.Another resistance source that can influence semi-conductor electricity device performance is the body resistance of semi-conductor itself.In nearly all semiconducter device, electric current all flows through the not depletion region of semiconductor body.The resistance relevant with flowing through these regional electric charges usually is very big, and can be the undesirable factor of limiting device performance sometimes.By means of strengthen semi-conductive doping in these zones as far as possible, the resistance relevant with these zones can be accomplished as far as possible little.Novel method of the present invention has made things convenient for this as far as possible doping being done greatly to various concentration levels of before can not having reached once more in these zones.

The present invention also can be used to make and the doped semiconductor device.This structure is based on extremely thin and very heavily doped semiconductor layer.The electric property of δ doping device is decided by to make the doping agent of maximum to enter the ability of the thin layer of maximum possible.The CVD method of having improved makes it to become the ability of the possible degeneracy doped level of controlling compound semiconductor better, should improve obtainable performance in the δ doping device architecture significantly.

The CVD method of having improved also can be used to develop the littler semiconducter device of depletion widths.The depletion widths that the various knots of semiconducter device (for example pn knot, metal semiconductor junction, heterojunction) are located is decided by the semiconductor doping around knot place or the knot to a great extent.As everyone knows, depletion widths reduces with the doping content increase.The performance and/or the function of a lot of semiconducter device depend on heavy doping to obtain narrow depletion widths and relevant physical influence.Zener diode and tunnel diode depend on the tunneling effect of current carrier by very narrow depletion region, and this ties two limit heavy doping by pn just becomes possibility.Low electric leakage diode and diode junction type charge storaging capacitor device based on narrow depletion widths so that electric current produces minimum and Charge Storage density maximum.Because the CVD method of having improved can be carried out heavy doping and obtained less depletion widths, so the CVD method of having improved has the potential of performance of improving these devices with the method for reduction of device depletion widths.

The CVD method of having improved also can be used to develop the narrow slightly semiconducter device of band gap.Mix by means of the degeneracy that improves in the semi-conductor, the bandtail portion decay of knowing is the physical phenomenon that band gap narrows down.The CVD technology of having improved can be used to control the degeneracy doping level in the used semi-conductor of the device (band gap wherein narrows down and improved device performance) of photodiode (LED) and bipolar transistor and so on.

Except the controllable growth of high quality compound semiconductor epitaxial film with higher-doped concentration, the CVD technology of having improved can grow in the past can not obtain have a high quality compound semiconductor epitaxial film than low doping concentration.Its performance benefits all will be benefited from the CVD method that this has improved in any compound semiconductor electricity device of low doping concentration.This device with benefit comprises basic semiconducter junction.Nearly all semiconducter device and circuit all comprise basic semiconducter junction.The most of transistors that become by these basic roped parties are arranged in the various structures that are suitable for finishing desirable electrical functions (for example amplify, switch).Utilize the basic knot that has improved of the present invention to mix, these devices will be greatly improved.A basic boom of semi-conductor electricity device technology is the tight joint of p section bar material and n section bar material, is called the pn knot more at large.Person skilled in the art are well-known, and the physical property than the light dope side (being doping density, defect concentration) that the electrology characteristic (as the voltage breakdown of junction capacitance, knot, the leakage current of knot) of pn knot is tied is dominated.Produce the ability that the lighter compound semiconductor of doping obtains required polarity (n type or p type) simultaneously again with this CVD method of having improved, greatly widened the scope of the electric property that might move in the device that contains the pn knot.As everyone knows, the voltage breakdown of pn junction diode increases with the doping decline of the lighter side of doping of knot.Therefore, the CVD method of having improved has shown that 10 times or bigger doping content improve (promptly reducing), when using the 6H-SiC crystal, can improve 6H-SiC pn step junction diode and stop voltage, make the maximum value that is obtained at present be a bit larger tham 1100V and bring up to about about 10000V.Also play significant feature in a similar manner in the semi-conductive electrology characteristic that to be entrained in another kind of basic knot be metal semiconductor junction.For the rectification metal-SiC Schottky diode junction of appropriate design, can expect has the improvement of analog result.The CDV method of having improved also can be used in transistor and the circuit layout to reach higher circuit voltage.

The CVD method of having improved also can be used to make the semi-conductor that junction capacitance has reduced.As everyone knows, the junction capacitance of diode reduces with the reduction of mixing.This CVD method of having improved makes it to become possible lighter doping and also can cause the depletion capacitance of compound semiconductor knot to reduce, and this usually will reduce can limiting device and the stray capacitance of circuit performance.One of the switching speed of restriction flat field effect transistor (FET) and factor of high frequency performance are by the formed stray capacitance of leakage-lining p-n diode junction.Can reduce this junction capacitance and might make compound semiconductor FET work in the higher frequency and the switching speed of deenergizing and reach with the available doping that has reduced of this CVD method of having improved than crossing.

The CVD method of having improved also can be used to make the high semiconducter device of internal resistance rate.Known resistivity reduces and increases with shallow ionization energy concentration of dopant.In the application of a lot of semiconducter device and unicircuit, making element manufacturing is favourable in high resistivity (dopant concentration) material.This material usually provides isolation between the adjacent devices of same chip; And isolated degree has determined the distance between the adjacent devices in the chip, and this is extremely important for thousands of transistorized unicircuit are arranged.Because isolation partly is the function of semi-conductor purity between the individual devices (being doping density and defect concentration), thus in reduction of device space advantageously so that on same chip, hold aspect the more device, the CVD method of having improved is provable to be useful.Obviously, for hope any device of the compound semiconductor epitaxial layer of high resistivity or the situation of circuit are arranged more, present method is useful.

The higher crystal of carrier mobility that the CVD method of having improved also can be used to grow and is used for semiconducter device.Known carrier mobility is with mixing and the reducing and increase of defect density.This is because the electromotive force disturbance (being caused by impurity and defective) that current carrier (electronics or hole) is run into during by lattice under electric field influence is less.Can grow doping agent unintentionally of the growth method of having improved enters lower this fact of purer material and should be able to improve carrier mobility in the compound semiconductor.The one skilled in the art is well-known, carrier mobility directly influences the performance of a lot of devices and circuit, and, be attractive so improve carrier mobility because higher carrier mobility improves the particularly transistorized performance of most of semiconducter device.In most of transistors, higher carrier mobility all improves crucial electric property (switching speed, maximum operation frequency, current load capacity, gain) usually.

The CVD method of having improved can be used to grow carrier lifetime higher crystal.Carrier lifetime be compound semiconductor another can by means of growth background defect density still less purer crystal and the physical properties that is improved.The one skilled in the art is well-known, and bulk carrier lifetime reduces with lattice defect concentration and increases.The improvement of this character can cause in the device littler compound/produce speed, make such as performance to improve based on the device of some kind of the device of few son.The device based on few son such as bipolar transistor and solar cell can be benefited from the long life-span.

With the SiC crystal of the CVD method growth that has improved, its possible industrial application comprises: the semiconducter device and the transmitter that are used for the hot environment the steam turbine engine, space power generation system, deep drilling exploration, advanced motor car engine or the like such as the advanced person; Be used for semiconducter device and transmitter near the high radiation environment of nuclear reactor and so on; Be used for electric locomotive, the space power system of requirement power regulation electronics and be used on the advanced aircraft driven by power the semiconducter device of the power electronics applications of demand; Be used on telstar, high-speed computing machine and be used for the semiconducter device of the frequency applications the microwave power transistor of radar system; The pressure transducer diaphragm material that is used for high temperature and/or corrosive atmosphere; And the photodiode (LED) that is used for hot environment.

As mentioned above, the important improvement of production doped crystal aspect is to control crystalline contamination content and/or concentration of dopant in the crystal growing process by means of change crystal source component concentrations in crystal growing process.Before being used for crystal to chemical vapour deposition (CVD) growth carries out more adulterated technology very big shortcoming is arranged, and can not make of technology made the sort of disclosed in this invention and that apply for claim and repeat to reappear and the crystal of doping agent controllable number.A major limitation to SiC crystal growth progress is obtainable limited repeatably doping scope.With controllable mode repeatably to clean carrier concentration less than 3 * 10 ¹⁶Cm ^-3Or greater than 5 * 10 ¹⁸Cm ^-3The SiC epitaxial film carry out prior art and mix, be impossible so far.The lower bound (3 * 10 of doping scope ¹⁶Cm ^-3) limited the high-pressure electronic application.The upper bound (5 * 10 of doping content ¹⁸Cm ^-3) require to carry out the annealing of metallic contact with specific pyroprocess.Opposite with prior art, the invention provides a repeatably doping scope of having expanded greatly, from 1 * 10 ¹⁴Cm ^-3Or littler, arrive greater than 1 * 10 ¹⁹Cm ^-3For the production of the electron device that can bear the voltage more much higher, need the low-down epitaxial film that mixes than existing device.Very highly doped epitaxial film allows metallic contact not require the high-temperature annealing process of prior art.

By means of the position competition (position competition extension) of specific contamination of control and/or doping agent, the significant improvement of the quantity of control contamination and/or doping agent in the crystal that has obtained in vapor deposition process, to grow.With can grow many kinds of crystal such as the SiC crystal of CVD method.SiC crystalline growth adopts silicon source and carbon source to realize, wherein the Si atom only occupies the Si position of SiC lattice and the C atom only occupies the C position.The Si position is also referred to as the Si growth position, is also referred to as the C growth position as the C position.When the SiC crystal was doped, the dopant atom such as phosphorus, nitrogen, aluminium, boron alternatively occupied Si position or the C position in the SiC lattice.Found by means of the Si/C concentration rate in the control CVD reaction chamber, can control the specific Si position that occupies in the SiC lattice or the dopant atom quantity of C position.Particularly found to keep the constant concentration of dopant simultaneously, can increase or reduce entering of specific p type doping agent by means of the Si/C concentration rate that changes in the CVD reaction chamber.The raising of Si/C concentration rate can make Si with dopant atom contention Si position, and the decline of Si/C concentration rate can make C with dopant atom contention C position.By means of control Si/C concentration rate, can accurately control the quantity that enters the SiC crystalline doping agent of growing.The control of Si/C concentration rate is directly influenced the position competition of Si position and C position.Find that also position competition extension can be used for two faces (being Si face and the C face of SiC (substrate)) of substrate.For the SiC crystal, position competition extension has been successfully used to various lattice types (being 6H, 4H and 3C).Utilize adulterating method disclosed by the invention and the application claim, in the crystal of growth in succession, can repeat to obtain to have the crystal of the CVD technology growth of particular dopant concentration exactly.The art methods of CVD technology growing crystal is the crystal of duplication of production with even concentration of dopant reliably.Adopt position competition extension, can produce the almost completely identical crystal of many doping contents, its concentration ratio is before with much lower (when needs are low) of the concentration of dopant that art methods obtains or much higher (when needs are high).By means of handling the substrate of waiting to want growing crystal on it rightly, the crystal that growth obtains will be the high quality crystal of defective much less.This pre-treatment comprises the burn into polishing and makes groove to form required crystal growing surface on substrate.Substrate wittingly nucleation so that the control crystalline direction of growth and make that crystal growth is easier in the CVD technological process begins.Substrate also can have the pitch angle to make things convenient for the crystal growth of some type.

Further correction of the present invention is obvious.For example, can select the crystal element ratio so that from the crystal of growing, get rid of specific dopant atom effectively.In the doping scope of broadness, can realize this point.For example, compete epitaxy technology, can obtain eliminating, make it can not enter n type epitaxial film to improve the MOS Devices Characteristics to the aluminium (promptly in reactor) that is not intended to exist with the position.Prior art is got rid of counter doping atom (for example aluminium in the nitrating layer) and is made it not enter the crystal of growing without any way doped crystal (being SiC).In the outer layer growth process, each reactor is used specific nitrogen (n type doping agent) air-flow, can grow 5 * 10 ¹⁶Cm ^-3Nitrogen doping (n type) epitaxial film.Specific nitrogen gas stream is made slightly variation and the miscellaneous equipment difference of change to adapt to each growth reactor.This " is write out a prescription " once determining, just becomes unique ad hoc approach that particular reactor produces the particular dopant concentration that presents the particular electrical characteristic.The Al that is not intended to exist enters into crystal can infringement crystalline electrology characteristic.Until the present invention, these restrictions all can't overcome.Found to mix to obtain n=5 * 10 with nitrogen and so on ¹⁶Doped level can finish with a series of nitrogen gas stream relevant with appropriate Si/C ratio.Therefore, identical n type doped epitaxial layer (promptly 5 * 10 ¹⁶) can realize with the specific Si/C ratio and a series of nitrogen gas stream of wide region.So, can obtain getting rid of the method that generally is not intended to exist (residual) the contra-doping agent atom in growth reactor.Therefore, utilize big Si/C ratio can select the specific Si/C ratio of getting rid of specific undesirable contra-doping agent (aluminium is as the agent of p type contra-doping) and reach required n=5 * 10 simultaneously ¹⁶Cm ^-3N type (being that the nitrogen mixes) level of mixing.

Importantly whether the agent of p type contra-doping by mistake exists (as impurity) and need get rid of the doped n type epitaxial film from having a mind to.Specifically, the existing aluminium of reporting is owing to causing that defective is at SiO ₂Form in the oxide compound of/SiC MOS structure and MOS (Metal-oxide-semicondutor) device performance based on the device of Si-C is harmful to.The N=5E16 n type epitaxial film that has big relatively Si/C ratio (to get rid of residual Al) to make has improved the MOS device performance, and with the identical n=5E16 n type epitaxial film that relatively little Si/C ratio is made the MOS device performance is descended.And the sample of growing with big Si/C ratio contains less residual (being not intended to) Al, and a large amount of (being not intended to) Al has entered the sample with relatively little Si/C ratio growth.

Can prepare multiple " prescription " for the various crystal doping scopes of the crystalline of SiC crystal and so on.For example, confirmed and can grow and the SiC crystal of the single CVD growth of mixing with the Si/C ratio of wide region and corresponding doping agent air-flow.Producing one with a plurality of Si/C ratios, to have crystalline notion that specific dopant enters quantity be to be contradiction with selecting a single best Si/C ratio and coming the way of the prior art of independent control concentration of dopant by means of the doping agent flow velocity that change enters the growth room.These " prescriptions " can be stored in Computer Database that is used for the control of growing crystal doping agent and so on.As mentioned above, if will grow and have the SiC crystal that specific concentrations n type doping agent enters, just can choose a prescription this crystal of growing.And, if need very pure n type SiC crystal, just select to regulate selected Si/C ratio and n type doping agent flow velocity so that the n type doping agent of appropriate quantity enters the Si/C crystal but the contamination of Al and so on is prevented from entering the specific prescription of SiC crystalline.Perhaps, if need very pure p type SiC crystal, just select specific Si/C ratio and p type doping agent flow velocity to make the p type doping agent of appropriate quantity enter the SiC crystal but the contamination of N and so on is prevented from entering SiC crystalline prescription.Such as will be appreciated, if need the p type and the n type doping agent of some amount in the crystal that grows out, just can correspondingly set the crystal elemental ratio.Doping agent enters and/or stains to get rid of and depends on the important improvement that this important discovery of crystal elemental ratio is the adjustment crystal doping.Just there is method from the CVD growing crystal, to get rid of contamination up to the present invention.This control method is stain particularly important concerning the crystal electric property has the dopant concentration of much bigger harmful effect for entering crystalline.

Another embodiment of the present invention is to enter with the contamination that doping agent is got rid of in the crystal of CVD growth.For example, selected crystal prescription is so that the dopant atom B that doping agent A entering in the epitaxial single crystal layer of growing reduced by means of introducing wittingly makes dopant atom A (by mistake existing) withdraw from competition wittingly.This example the performance of resulting devices is had a disadvantageous effect at some dopant atom (even being present in the background concentration) those advantage is arranged in using.For example, aluminium and boron are the typical trace impurities that finds in the n type epitaxial film of nitrating intentionally.The undesirable electricity compensation to nitrogen, aluminium is also relevant with very poor MOS device performance except aluminium and boron.This is not intended to aluminium, and to enter the terms of settlement of problem (it causes inferior MOS device) as follows:

In nitrating n type outer layer growth process, simultaneously a kind of extra n type dopant atom (phosphorus for example, it is the identical crystallographic site of Al contention with undesirable p type dopant atom) is introduced reactor with nitrogen dopant (it enters the position that is different from P and Al).Specifically, in crystal growing process, phosphorus is introduced at the same time reactor to get rid of any residual Al, makes it can not enter n type (mainly realizing as n type doping agent with nitrogen) epitaxial film.Because phosphorus and aluminium are all fought for the Si crystallographic site among the SiC, so the eliminating of Al is successful.Because phosphorus also is a kind of n type dopant atom, so entering of phosphorus do not play harmful effect to crystal.The mixture of phosphorus and nitrogen is as having a mind to n type doping agent, and this just provides the method for a kind of eliminating as the undesirable Al of residual compensatory p type doping agent.Outside the dephosphorization, fluorine, chlorine and sulphur also can be used to from Si position eliminating aluminium.

As can be appreciated, utilize the n type doping agent that occupies the Si position such as nitrogen, hydrogen, chlorine and/or sulphur, in n type doping process, can get rid of other p type doping agents such as boron, sodium, iron, gallium, titanium and vanadium that occupy the Si position.Perhaps, utilize sodium, iron, aluminium, gallium, titanium and vanadium, in p type doping process, can get rid of the n type doping agent such as nitrogen, fluorine, p and s.Utilize this method, a kind of p type doping agent that occupies the C position of employing such as boron, select one to get rid of and be not intended to the p type doping agent (being Na, Fe, Al, Ga, Ti, V) that n type doping agent enters the Si/C ratio of Si position and introduce a kind of Si of contention position and enter crystal, the p type doped crystal that can grow very pure with further eliminating n type doping agent.

The application profiles of this method is as follows:

1. mix the n type with P (phosphorus), and

A. (that is i. reduces the electricity compensation of the n type epitaxial film of nitrating to stop Al (p type) to enter the Si position; Ii. further accelerate the reversing from the p type to the n type in the crystal epitaxial layer process of growth).

B. stop N to enter the Si position; Especially at (also on Si face and A face sample) on the C face sample, may have precedence over N and enter the Si position because N enters the C position.

C. stoping N to enter the Si position also uses high relatively Si source/C source ratio to enter the Si position to stop N better simultaneously.

D. stop B (boron) to enter the Si position and mainly enter the C position to force B; 1) stop H enter crystal (just think that B H when the Si position just enters, when B during in the C position H do not enter).

E. stop Ga (gallium), Ti (titanium), V (vanadium), Na (sodium) to enter the Si position.

2. come doping p-type with B (boron), and

A. stop Al to enter the Si position, thereby stop Al (have a mind to and/or be not intended to) to enter crystal.

B. stop N to enter the Si position, particularly, stop N to enter the Si position simultaneously thereby force N to enter the C position on the C face but some are also arranged on the Si face.

3. mix the n type with O (oxygen), and

A. stop B to enter the C position.

B. stop N to enter the C position, may have precedence over N and enter the C position because N enters the Si position.

4. mix the n type with P (phosphorus), and

A. stop Na to enter the Si position.

B. stop S to enter the Si position.

It is that binding site competition extension is selected specific crystal face that of the present invention another becomes example.Particularly, find that the doping agent admission rate depends on specific crystal face.For example, nitrogen mainly enters the Si position on the SiC substrate C face.Yet nitrogen mainly enters the C position on SiC substrate Si face and the A face.Therefore, when crystal is grown on the C of substrate face, can stop p type doping agent to enter the Si position with nitrogen such as aluminium.On the contrary, by means of growing crystal on the C face and in the growth room, add Al, Na, Fe, Ga, Ti and/or V and enter the Si position, can stop nitrogen to enter the p N-type waferN to stop N.

With reference to most preferred embodiment and change example thereof the present invention has been described.Believe that person skilled in the art read and understand after the detailed description of the present invention at an easy rate imagination to many corrections and the change of embodiment.All these corrections and change are all within the scope of the present invention.

Claims (76)

1. One kind with CVD technology in the growth room in certain zone in the growing crystal process adjustment be deposited at least the method for the amount of the noncrystal element in the given growth district of the monocrystalline elementary composition by two kinds of crystal, above-mentioned crystal element comprises the first crystal element and the second crystal element, above-mentioned crystal has two kinds of growth positions at least, the wherein above-mentioned first crystal element is deposited on first growth position and the above-mentioned second crystal element is deposited on second growth position, above-mentioned noncrystal element is competitive in above-mentioned first and second growth positions at least one, and aforesaid method comprises the following step:

   The gaseous state crystal element compound that quantity is controlled flows through above-mentioned growth room, and each in the wherein above-mentioned element compound comprises in the above-mentioned crystal element at least,

   B. in above-mentioned crystalline process of growth, the ratio that changes the gaseous state crystal element compound that above-mentioned quantity is controlled is to be adjusted at the above-mentioned quantity that is deposited on the above-mentioned noncrystal element in the above-mentioned competitive crystal growth position in the above-mentioned growth district.
2. 2. the described method of claim 1, wherein said noncrystal element is mainly fought for above-mentioned first growth position.
3. 3. the described method of claim 2 comprises by means of improving the above-mentioned second crystal element compound improves the deposition rate of above-mentioned noncrystal element in above-mentioned first growth position to the above-mentioned ratio of the above-mentioned first crystal element compound step.
4. 4. the described method of claim 2 comprises by means of reducing the above-mentioned second crystal element compound reduces the deposition rate of above-mentioned noncrystal element in above-mentioned first growth position to the above-mentioned ratio of the above-mentioned first crystal element compound step.
5. 5. the described method of claim 3, wherein said noncrystal element is a kind of doping agent.
6. 6. the described method of claim 4, wherein said noncrystal element is a kind of doping agent.
7. 7. the described method of claim 5, comprise above-mentioned growth surface is carried out pre-treatment can be in above-mentioned crystal growing process to remove as the impurity on the above-mentioned growth surface of heterogeneous nucleation position and the step of crystalline structure.
8. 8. the described method of claim 7, wherein said crystal growth is on the growth surface of substrate.
9. 9. the described method of claim 8, the growth surface of wherein said above-mentioned substrate has the inclination of a non-zero with respect to base plane.
10. 10. the described method of claim 8, the growth surface of wherein said above-mentioned substrate does not tilt with respect to base plane.
11. 11. the described method of claim 9, wherein said non-zero tilts approximately greater than 7 ℃.
12. 12. the described method of claim 1, wherein said growth room is heated to 800-2200 ℃ temperature.
13. 13. the described method of claim 7, wherein said pre-treatment comprise the preceding corrosion of the growth of above-mentioned growth surface.
14. 14. the described method of claim 7, wherein said pre-treatment comprise above-mentioned growth surface is polished.
15. 15. the described method of claim 9 comprises by means of the border along above-mentioned vitellarium and introduces the step that groove is divided into above-mentioned vitellarium a plurality of vitellariums.
16. 16. the described method of claim 8 is included on the above-mentioned substrate nucleation with the many types of step of growth particular crystal.
17. 17. the described method of claim 16, the nucleation of wherein said above-mentioned substrate are to introduce suitable impurity to promote the growth of required crystalline structure in above-mentioned position.
18. 18. the described method of claim 17, wherein the position of above-mentioned nucleation is on the angle of above-mentioned vitellarium.
19. 19. the described method of claim 1, wherein said element are mainly fought for above-mentioned second growth position.
20. 20. the described method of claim 19 comprises by means of improving the above-mentioned first crystal element compound improves the deposition rate of above-mentioned noncrystal element in the above-mentioned second element growth position to the above-mentioned ratio of the above-mentioned second crystal element compound step.
21. 21. the described method of claim 19 comprises by means of reducing the above-mentioned ratio of the above-mentioned first crystal element compound to above-mentioned second crystalline compounds and reduces the deposition rate of above-mentioned noncrystal element in the above-mentioned second element growth position.
22. 22. the described method of claim 20, wherein said noncrystal element is a kind of doping agent.
23. 23. the described method of claim 21, wherein said noncrystal element is a kind of doping agent.
24. 24. the described method of claim 22, comprise above-mentioned growth surface is carried out pre-treatment can be to remove in the above-mentioned crystal growing process as the impurity on the above-mentioned growth surface of heterogeneous nucleation position and the step of crystalline structure.
25. 25. the described method of claim 23, comprise above-mentioned growth surface is carried out pre-treatment can be to remove in the above-mentioned crystal growing process as the impurity on the above-mentioned growth surface of heterogeneous nucleation position and the step of crystalline structure.
26. 26. the described method of claim 1 comprises with carrier gas above-mentioned crystal element is introduced the step of above-mentioned growth room.
27. 27. a growth contains the crystalline method of the noncrystal element of selected concentration, above-mentionedly grow with the technology of carrying out in the growth room by two kinds of elementary composition crystal of crystal at least, above-mentioned crystal has two kinds of growth positions at least, and above-mentioned noncrystal element is competitive to growth position, and aforesaid method comprises:

    A) determine the above-mentioned growth position that above-mentioned noncrystal element is fought for;

    B) determine to be deposited on crystal element in the above-mentioned growth position of above-mentioned noncrystal element contention; And

    C) control contain some amount in above-mentioned crystal growing process with the crystal elemental ratio of the competition crystal element of above-mentioned noncrystal element competition so that the noncrystal element of desired number enters above-mentioned growth position.
28. 28. the described method of claim 27, wherein said control crystal elemental ratio comprise the crystal elemental ratio of selecting and keeping selecting.
29. 29. the described method of claim 27, wherein said control crystal elemental ratio comprise the crystal elemental ratio of selecting and keeping selecting and select at least one different ratio and above-mentioned at least one different ratio is kept for some time in crystal growing process.
30. 30. the described method of claim 28, wherein said crystal elemental ratio is chosen, contains concentration less than about 1.0 * 10 with production ¹⁶Cm ^-3The crystal of noncrystal element.
31. 31. the described method of claim 29, wherein said crystal elemental ratio is chosen, contains concentration less than about 1.0 * 10 with production ¹⁶Cm ^-3The crystal of noncrystal element.
32. 32. the described method of claim 30, wherein said noncrystal concentration of element is less than about 5.0 * 10 ¹⁵Cm ^-3
33. 33. the described method of claim 32, wherein said noncrystal concentration of element is less than about 1.0 * 10 ¹⁵Cm ^-3
34. 34. the described method of claim 33, wherein said noncrystal concentration of element is less than about 8.0 * 10 ¹³Cm ^-3
35. 35. the described method of claim 29, wherein said crystal elemental ratio is chosen, contains concentration greater than about 1 * 10 with production ¹⁹Cm ^-3The crystal of noncrystal element.
36. 36. the described method of claim 28, wherein said crystal elemental ratio is chosen, contains concentration greater than about 1 * 10 with production ¹⁹Cm ^-3The crystal of noncrystal element.
37. 37. the described method of claim 36, wherein said noncrystal concentration of element is greater than about 3.0 * 10 ¹⁹Cm ^-3
38. 38. the described method of claim 37, wherein said noncrystal concentration of element is less than about 5.0 * 10 ¹⁹Cm ^-3
39. 39. the described method of claim 38, wherein said noncrystal concentration of element is less than about 1 * 10 ²⁰Cm ^-3
40. 40. the described method of claim 39, wherein said noncrystal concentration of element is less than about 5.0 * 10 ²⁰Cm ^-3
41. 41. the described method of claim 29, wherein said crystal have a plurality of noncrystal concentration of element.
42. 42. the described method of claim 28, wherein said crystal have a plurality of noncrystal concentration of element.
43. 43. the described method of claim 37, wherein said crystal have a plurality of noncrystal concentration of element.
44. 44. the described method of claim 32, wherein said crystal have a plurality of noncrystal concentration of element.
45. 45. a growth contains the crystalline method of at least a p type doping agent of at least a n type doping agent of selected quantity and selected quantity, above-mentionedly grow with the technology of carrying out in the growth room by at least two kinds of elementary composition crystal of crystal, above-mentioned crystal has at least two kinds of growth positions and n type growth position mainly fought for by above-mentioned at least a n type doping agent and above-mentioned at least a p type doping agent is mainly fought for p type growth position, and aforesaid method comprises:

    A) definite above-mentioned crystal element that mainly is deposited in the above-mentioned p type growth position;

    B) definite above-mentioned crystal element that mainly is deposited in the said n type growth position; And

    C) by means of select and keep subsequently selected said n type growth position crystal element that contains some amount and above-mentioned p type growth position crystal unit usually the control element ratio to be deposited on the n type doping agent in the above-mentioned crystal and the quantity of p type doping agent in the control crystal growing process.
46. 46. a growth contains the method for the monocrystalline of the noncrystal element of selecting concentration, above-mentionedly grow with the technology of carrying out in the growth room by at least two kinds of elementary composition monocrystalline of crystal, above-mentioned monocrystalline has at least two kinds of growth positions, and above-mentioned noncrystal element is fought for a kind of growth position, and aforesaid method comprises:

    A) determine the above-mentioned growth position that above-mentioned noncrystal element is fought for;

    B) determine to be deposited on crystal element in the above-mentioned growth position of above-mentioned noncrystal element contention;

    C) control contain some amount in above-mentioned crystal growing process with the crystal elemental ratio of the competition crystal element of above-mentioned noncrystal element competition, make 〉=1 * 10 ¹⁹Cm ^-3Noncrystal element enter above-mentioned crystal.
47. 47. a growth contains the method for the monocrystalline of the noncrystal element of selecting concentration, above-mentionedly grow with the technology of carrying out in the growth room by at least two kinds of elementary composition monocrystalline of crystal, above-mentioned monocrystalline has at least two kinds of growth positions and above-mentioned noncrystal element is fought for a kind of growth position, and aforesaid method comprises:

    A) determine the above-mentioned growth position that above-mentioned noncrystal element is fought for;

    B) determine to be deposited on crystal growth in the above-mentioned growth position of above-mentioned noncrystal element contention;

    C) control contains the crystal elemental ratio of the competition crystal element of competing with above-mentioned noncrystal element of some amount in above-mentioned crystal growing process, make≤1.0 * 10 ¹⁵Cm ^-3Noncrystal element enter above-mentioned monocrystalline.
48. 48. a growth contains the crystalline method of the noncrystal element of selected concentration, above-mentionedly grow with the technology of carrying out in the growth room by at least two kinds of elementary composition crystal of crystal, above-mentioned monocrystalline has at least two kinds of growth positions and above-mentioned noncrystal element is fought for a kind of growth position, and aforesaid method comprises:

    A) determine the above-mentioned growth position that above-mentioned noncrystal element is fought for;

    B) determine to be deposited on crystal element in the above-mentioned growth position of above-mentioned noncrystal element contention;

    C) the basic constant concentration that keeps above-mentioned noncrystal element in above-mentioned growth room;

    D) desired number of the noncrystal element that decision is to be entered; And

    E) by means of control contain some amount in above-mentioned crystal growing process will with the crystal elemental ratio of the competition crystal element of above-mentioned noncrystal element competition, the above-mentioned monocrystalline of the noncrystal element that has above-mentioned desired number of growing.
49. 49. when a CVD technology of carrying out in the growth room when the SiC crystal is grown on the aforementioned region, be used for controlling the system of the quantity that is deposited on the chosen elements in the given vitellarium of the crystalline of forming by Si and C, wherein said Si is deposited in the Si growth position and C is deposited in the C growth position, above-mentioned element is mainly fought for a kind of in the above-mentioned growth position, and said system comprises the device that the gaseous state Si compound that is used for making first quantity flows through above-mentioned growth room, be used for making the gaseous state C compound of second quantity to flow through the device of above-mentioned growth room, and the ratio that is used for controlling above-mentioned first and second quantity is deposited on the device of the above-mentioned quantity of the above-mentioned element in the above-mentioned crystal in the aforementioned region with control.
50. 50. when a CVD technology of carrying out in the growth room when above-mentioned crystal is grown on the aforementioned region, be used for controlling the system that is deposited on by the quantity of the noncrystal element in the elementary composition given vitellarium of crystalline of at least two kinds of crystal, above-mentioned crystal element comprises the first crystal element and the second crystal element, above-mentioned crystal has at least two kinds of crystal growth positions, the wherein above-mentioned first crystal element is deposited on first growth position and the above-mentioned second crystal element is deposited on second growth position, above-mentioned noncrystal element is fought at least a in the above-mentioned growth position, and said system comprises that ratio that the gaseous state crystal element compound that is used for quantity is controlled flows through the device (each in the wherein above-mentioned element compound comprises a kind of above-mentioned crystal element at least) of above-mentioned growth room and is used for controlling the gaseous state crystalline compounds that above-mentioned quantity is controlled is deposited on the device of the above-mentioned quantity of the above-mentioned noncrystal element in the above-mentioned crystal with control.
51. 51. the described method of claim 50, wherein said dopant element are mainly fought for above-mentioned first growth position, above-mentioned contamination element is mainly fought for above-mentioned second growth position.
52. 52. the described method of claim 51 is included in the above-mentioned dopant element of the selected quantity of deposit in above-mentioned the first growth position and the quantity of the above-mentioned dopant compound of the monocrystalline of the above-mentioned dopant element with selected quantity of growing by means of the ratio ranges of determining above-mentioned gaseous state crystal element compound with when the speed that concentration that above-mentioned ratio comprises sufficiently high above-mentioned the second crystal element has reduced with the above-mentioned contamination element in above-mentioned the second growth position that obtains to be deposited on above-mentioned crystal above-mentioned reduces the step that is deposited on the above-mentioned contamination element speed in above-mentioned the second growth position.
53. 53. a selection is deposited on the quantity of the dopant element in the given vitellarium of monocrystalline and the method that reduction is deposited on the quantity of the contamination element in this given single crystal growing district, when the CVD technology of carrying out in the growth room when above-mentioned crystal is grown on the zone, above-mentioned monocrystalline is elementary composition by at least two kinds of crystal, above-mentioned crystal element comprises the first crystal element and the second crystal element, above-mentioned monocrystalline has two kinds of crystal growth positions at least, the wherein above-mentioned first crystal element is deposited in first growth position and the above-mentioned second crystal element is deposited on the second element growth position, a kind of in above-mentioned at least first and second growth positions of above-mentioned dopant element contention, above-mentioned contamination element is fought for the growth position beyond the above-mentioned dopant element growth position, and aforesaid method comprises the following step:

    A) determine the above-mentioned growth position that above-mentioned dopant element is fought for;

    B) determine the above-mentioned growth position that above-mentioned contamination element is fought for;

    C) determine to be deposited on the first crystal element in the above-mentioned growth position of above-mentioned dopant element contention;

    D) make the gaseous state crystal element compound of selected quantity flow through above-mentioned growth room, each in the wherein above-mentioned element compound comprises above-mentioned first and the above-mentioned second crystal element;

    E) select the ratio of the above-mentioned gaseous state crystal element compound that is controlled in the above-mentioned crystal growing process to be deposited on the above-mentioned quantity of the above-mentioned dopant element in the above-mentioned competitive crystal growth position with control; And

    F) select the ratio of the above-mentioned above-mentioned gaseous state crystal element compound that is controlled to reduce to be deposited on the above-mentioned quantity of the above-mentioned contamination element in the above-mentioned competitive crystal growth position.
54. 54. the described method of claim 53 comprises by means of improving the above-mentioned second crystal element compound improves the speed that is deposited on the above-mentioned dopant element in the above-mentioned competitive growth position to the above-mentioned ratio of the above-mentioned first crystal element compound step.
55. 55. the described method of claim 53 comprises by means of reducing the above-mentioned second crystal element compound reduces the speed that is deposited on the above-mentioned dopant element in the above-mentioned competitive growth position to the above-mentioned ratio of the above-mentioned first crystal element compound step.
56. 56. the described method of claim 55, wherein said crystal elemental ratio is chosen, with production contain＜1.0 * 10 ¹⁶Cm ^-3The crystal of dopant element concentration.
57. 57. the described method of claim 55, wherein said dopant element concentration is less than 5.0 * 10 ¹⁵Cm ^-3
58. 58. the described method of claim 54, the chosen production of wherein said crystal elemental ratio contained greater than 1.0 * 10 ¹⁹Cm ^-3The crystal of dopant element concentration.
59. 59. the described method of claim 54, wherein said dopant element concentration is greater than 5.0 * 10 ¹⁹Cm ^-3
60. 60. the described method of claim 53, the ratio that is included in the quantity that changes the once above-mentioned gaseous state crystal element compound that is controlled in the above-mentioned crystalline process of growth at least is to make the crystalline step that has two kinds of different dopant element concentration at least.
61. 61. the described method of claim 57, the ratio that is included in the quantity that changes the once above-mentioned gaseous state crystal element compound that is controlled in the above-mentioned crystalline process of growth at least is to make the crystalline step that has two kinds of different dopant element concentration at least.
62. 62. the described method of claim 59, the ratio that is included in the quantity that changes the once above-mentioned gaseous state crystal element compound that is controlled in the above-mentioned crystalline process of growth at least is to make the crystalline step that has two kinds of different dopant element concentration at least.
63. 63. the described method of claim 62 comprise the step of second dopant element that the electric polarity that adds some amount is identical with above-mentioned dopant element, and above-mentioned second doping agent is fought for the above-mentioned growth position that above-mentioned contamination element is fought for.
64. 64. the described method of claim 60 comprise the step of second dopant element that the electric polarity that adds some amount is identical with above-mentioned dopant element, and above-mentioned second doping agent is fought for the above-mentioned growth position that above-mentioned contamination element is fought for.
65. 65. the described method of claim 61 comprise the step of second dopant element that the electric polarity that adds some amount is identical with above-mentioned dopant element, and above-mentioned second doping agent is fought for the above-mentioned growth position that above-mentioned contamination element is fought for.
66. 66. the described method of claim 62 comprise the step of second dopant element that the electric polarity that adds some amount is identical with above-mentioned dopant element, and above-mentioned second doping agent is fought for the above-mentioned growth position that above-mentioned contamination element is fought for.
67. 67. the described method of claim 63, the quantity of wherein said second dopant element are increased to reduce entering of above-mentioned contamination element in the above-mentioned crystal.
68. 68. the described method of claim 64, the quantity of wherein said second dopant element are increased to reduce entering of above-mentioned contamination element in the above-mentioned crystal.
69. 69. the described method of claim 65, the quantity of wherein said second dopant element are increased to reduce entering of above-mentioned contamination element in the above-mentioned crystal.
70. 70. the described method of claim 66, the quantity of wherein said second dopant element are increased to reduce entering of above-mentioned contamination element in the above-mentioned crystal.
71. 71. a selection is deposited on the quantity of first dopant element in the given vitellarium of monocrystalline and second dopant element and reduces to be deposited on the method for the quantity of the contamination element in the given vitellarium of this monocrystalline, when the CVD technology of carrying out in the growth room when above-mentioned crystal is grown on certain zone, above-mentioned monocrystalline is elementary composition by at least two kinds of crystal, above-mentioned first has identical electric polarity with above-mentioned second dopant element, above-mentioned crystal element comprises the first crystal element and the second crystal element, above-mentioned monocrystalline has two kinds of crystal growth positions at least, the wherein above-mentioned first crystal element is deposited in the first element growth position and the above-mentioned second crystal element is deposited in the second element growth position, above-mentioned dopant element is fought for a kind of in above-mentioned first and second growth positions at least, above-mentioned contamination element and above-mentioned second dopant element are fought for the growth position outside the above-mentioned growth position of above-mentioned first dopant element, and aforesaid method comprises the following step:

    A) determine the above-mentioned growth position that above-mentioned dopant element is fought for;

    B) determine the above-mentioned growth position that above-mentioned contamination element and above-mentioned second dopant element are fought for;

    C) determine to be deposited on the first crystal element in the above-mentioned growth position of above-mentioned dopant element contention;

    D) determine to be deposited on the second crystal element in the above-mentioned growth position of above-mentioned contamination element and above-mentioned second dopant element contention;

    E) the gaseous state crystal element compound that quantity is controlled flows through above-mentioned growth room, and each in the wherein above-mentioned element compound comprises at least a above-mentioned crystal element;

    F) first doping agent and second doping agent that quantity is controlled flows through above-mentioned growth room;

    G) in above-mentioned crystalline process of growth, select the ratio of the above-mentioned quantity that is controlled of above-mentioned gaseous state crystal element compound to be deposited on the above-mentioned quantity of above-mentioned first dopant element in the above-mentioned competitive crystal growth position with control; And

    H) ratio of the above-mentioned quantity that is controlled of the above-mentioned gaseous state crystal element compound of selection is to reduce to be deposited on the quantity of the above-mentioned contamination element in the above-mentioned competitive crystal growth position and the quantity of above-mentioned second doped element.
72. 72. the described method of claim 65, the wherein said first crystal element is only fought for first growth position, the above-mentioned second crystal element is only fought for second growth position, above-mentioned first dopant element is mainly fought for above-mentioned first growth position with the above-mentioned first crystal element, above-mentioned contamination element and above-mentioned second dopant element are mainly fought for above-mentioned second growth position with the above-mentioned second crystal element, and above-mentioned contamination element and above-mentioned second dopant element are fought for above-mentioned second growth position.
73. 73. the described method of claim 71 comprises that the flow rate that improves above-mentioned second doping agent enters the step of the above-mentioned quantity of the above-mentioned contamination of above-mentioned crystalline with further reduction.
74. 74. the described method of claim 73, the ratio that comprises the quantity of regulating the above-mentioned gaseous state crystal element compound that is controlled is to obtain the step that needed doping agent enters in the above-mentioned crystal.
75. 75. a selection is deposited on the quantity of the dopant element in the given vitellarium of monocrystalline and the method that reduction is deposited on the quantity of the contamination element in the given vitellarium of this monocrystalline, when the CVD technology of carrying out in the growth room when above-mentioned crystal is grown in certain zone, above-mentioned monocrystalline is elementary composition by at least two kinds of crystal, above-mentioned crystal element comprises the first crystal element and the second crystal element, above-mentioned monocrystalline has two kinds of crystal growth positions at least, the wherein above-mentioned first crystal element is deposited on first growth position and the above-mentioned second crystal element is deposited on the second element growth position, above-mentioned dopant element is mainly fought for above-mentioned first location, above-mentioned contamination element is mainly fought for above-mentioned second growth position, and aforesaid method comprises the following step:

    A) chosen dopant enters above-mentioned crystalline degree;

    B) select the flow rate of the ratio of the above-mentioned quantity that is controlled of gaseous state crystal element compound in the above-mentioned crystal growing process and above-mentioned doping agent to be deposited on the above-mentioned quantity of the above-mentioned dopant element in above-mentioned first growth position with control; And

    C) make the gaseous state crystal element compound and the doping agent of selected quantity flow through above-mentioned growth room, wherein each above-mentioned element compound comprises the first and second crystal elements.
76. 76. the described method of claim 75, thereby comprise by means of regulating above-mentioned ratio and reduce and stain ingress rate and further reduce and enter the above-mentioned contamination of above-mentioned crystalline to improve the doping agent ingress rate, and selection corresponding to the reduction of the ratio of regulating the doping agent flow rate to reach the step that needed doping agent enters above-mentioned crystalline degree.

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