CN101308822B - Method of manufacturing cmos devices by implantation of N- and P-type cluster ions - Google Patents

Abstract

An ion implantation system (10) is described for the implantation of cluster ions into semiconductoe substrates for semiconductor device manufacturing. A method of manufacturing a semiconductor device is described, wherein clusters of N-and P-type dopants are implanted to form the transistor in CMOS devices. For example, As4Hx+ clusters and either B10Hx or B10HX+ clusters are used as sources of As and B doping, respectively, during the implants. An ion implantation system (10) is described for the implantation of cluster ions into semiconducteur substrates for semiconductor device manufacturing.

Description

Manufacture the method for cmos device by implanting N-and P-type cluster ion and anion

the related application cross reference

The application's case is advocated have precedence over and advocate U.S. Provisional Patent Application case the 60/392nd, and No. 271 and the 60/391st, the right of No. 847, these two temporary patent application cases are all filed an application on June 26th, 2002.Present application for patent also advocates to have precedence over the U.S. patent application case the 10/244th of owning together and coexisting in applying for, No. 617 (on September 16th, 2002 files an application) and U.S. patent application case the 10/251st, No. 491 (on September 20th, 2002 files an application).

Background of invention

Technical field

The present invention relates to a kind of implanted ions system and a kind of semiconductor making method, it is for implanting bunch ion beam formed and the electronegative ion beam by N-type dopant cluster ion.

Background technology

The manufacture of semiconductor device can partly relate to introduces impurity to form doped region in Semiconductor substrate.Selected impurity element should form electric charge carrier with the suitable combination of semi-conducting material and change the conductance of semi-conducting material.Wherein, electric charge carrier both can be electronics (being produced by N-type dopant) and also can be hole (being produced by P-type dopant).The concentration of the dopant impurities of introducing can determine the conductivity in the zone that obtains thus.For forming transistor arrangement, insulation system and other these electronic structures (it is completely as semiconductor device), must form many these N-types and P-type extrinsic region.

For conventional method that dopant is introduced to Semiconductor substrate, be to pass through implanted ions.In implanted ions, be introduce in an ion source by a charging that contains required element and introduce energy by this charging ionization, contain dopant element (element for example thereby form ⁷⁵as, ¹¹b, ¹¹⁵in, ³¹p, or ¹²¹sb) ion.Then, provide an acceleration battery to extract and usually positively charged ion is accelerated, thereby forming ion beam.Then, as known as institute in affiliated technical field, the material that wish is implanted is chosen in the service quality analysis, and by ion beam directive semi-conductive substrate.The electric field accelerated can make ion have kinetic energy, thereby ion can be infiltrated through in target.The energy of ion and quality have determined that it infiltrates through the degree of depth in target, and the energy of its intermediate ion is larger and/or quality is less, and its speed can heal high, thereby infiltrate through in target darker.The implanted ions System Construction is for meticulously controlling the key variables of implanting technique, for example ion beam energy, ion beam quality, ion beam current (electric charge in time per unit), and at the ion dose (total number of ions of per unit area in infiltrating through target) at target place.In addition, for keeping the rate of finished products of semiconductor device, also must control ion beam angular divergence (variation of the angle of ionic bombardment substrate) and ion beam space uniformity and scope.

Recently, it is found that implanting anion can be better than implanting cation, for example, referring to: D.C.Jacobson, Konstantin Bourdelle, H-J.Gossmann, M.Sosnowski, M.A.Albano, V.Babaram, J.M.Poate, Aditya Agarwal, " the decaborane that Alex Perel and Tom Horsky show, a kind of alternative method (Decaborane implanted for ultra-low energy ion, anAlternative approach to Ultra Low Energy Ion Implantation) " (XIII international ion embedding technology meeting proceedings of the IEEE held at Austrian Alpsbach in 2000), " a kind of large electric current anion implanter and to manufacture the application (A High-Current Negative-Ion Implanter and its Application for:Nanocrystal Fabrication in Insulators) of nanocrystal in insulator " (the international ion embedding technology meeting of the IEEE XIIJie held at Japanese Kyoto 22-26 day in June, 1998 proceedings, (1999) 342-345) that the people such as N.Kishimoto show, " the low energy cation of mass separation and the ion beam of anion precipitation equipment characterize (BeamCharacterization of Mass-Separated, Low-Energy Positive and NegativeIons Deposition Apparatus) " that the people such as N.Tsubouchi show (the international ion embedding technology meeting of the IEEE XIIJie held at Japanese Kyoto 22-26 day in June, 1998 proceedings, (1999) 350-353), and " anion implanted prosthetics (Negative-Ion Implantation Technique) " (nuclear instrument in PhysicsResearch B 96 (1995) 7-12 and method (Nuclear Instruments andMethods)) of showing of the people such as Junzo Ishikawa.The very important advantage that anion is implanted is the surface charging that can be reduced in the VLSI device caused by implanted ions in the CMOS manufacture.Generally speaking, the large electric current of cation (in 1mA or the larger order of magnitude) implantation meeting produces positive potential on other assemblies of gate oxide and semiconductor device, and this kind of positive potential can surpass the damaging thresholding of gate oxide at an easy rate.When a cation clashes into semiconductor device surperficial, it not only can the clean positive charge of electrodeposition one, but also liberates secondary electron simultaneously, thereby makes the charge effect multiplication.Therefore, the equipment dealer of implanted ions system has developed a kind of at implantation process, low-energy electron being introduced to the electric charge control device that reaches the precision on the device disk surfaces in positively charged ion beam, i.e. so-called submerged electron gun.This kind of submerged electronic system can be introduced its dependent variable in manufacturing process, and can't thoroughly eliminate the rate of finished products loss caused because of surface charging.Along with semiconductor device becomes more and more little, transistorized operating voltage and gate oxide thickness also become more and more little, thereby can reduce the damaging thresholding in the semiconductor device manufacture, cause rate of finished products to decrease.Therefore, for much preface technique, anion implantation meeting more traditional cation aspect rate of finished products is implanted potential obvious improvement.Regrettably, this kind of technology is not yet on sale on the market, and in fact, just, known to the author, anion is implanted not yet for the manufacture of integrated circuit at present, even not yet for research and exploitation.

The prior art anion source is to depend on so-called negative adsorptivity sputter rake.Be wherein that a heavy inert gas (for example xenon) is fed into to a plasma source, by this plasma source, form Xe ⁺ion.Xe ⁺ion at once is drawn to one and bears the sputtering target of back bias voltage after formation, and this sputtering target has been coated with caesium steam or other suitable basic matterials.High energy X e ⁺ion can sputter away neutral target atom, and because the caesium coating has the negatron adsorptivity, thereby some neutral target atom can pick up an electronics when leaving the target surface.Once be with negative electrical charge, target ion can be by repulsion away from target, and can collect and be converged to a negative ion beam from ion source by the electrostatic ionic Optical devices.For example, although can use this kind of method to produce semiconductor dopant ion (boron), yet, ionic current is often on the low side, the ion beam emittance is often bigger than normal, and the existence meeting of caesium steam causes and makes us unacceptable risk wafer yield, this is because alkalinous metal is considered to the processing of meeting severe contamination silicon.Therefore, need to there is a kind of commercially more feasible anion source technology.

Especially be concerned about in semiconductor fabrication process and form the P-N knot in Semiconductor substrate.This requires to form adjacent N-type and P-type doped region.A general example that forms a knot is N-type dopant to be implanted to one contained in the semiconductor regions of an equally distributed P-type dopant.In this situation, an important parameter is junction depth, and it is defined as from N-type and P-type dopant has the degree of depth that the semiconductor surface of equal concentrations starts.This junction depth depends primarily on quality, energy and the dosage of implanted dopant.

An importance of modern semiconductor technology is constantly to less, device evolution faster.This process is called scaled (scaling).Scaled is the promotion that is subject to the continuous improvement progress of lithography process, and the continuous improvement progress of lithography process makes people can in containing the Semiconductor substrate of integrated circuit, define more and more less body.Formed at present a kind of well accepted scaled theory be used for instructing chip manufacturer suitably simultaneously (at each technology node or scaled Nodes) change the size aspect all in semiconductor device design.Scaled technology is that junction depth is scaled to maximum effect of ion implantation technology, and this requires to make along with reducing of device size knot day by day to shoal.This requirement that day by day shoals can show as following requirement along with integrated circuit technique is scaled to make knot: in each scaled step, all must reduce the implanted ions energy.Recently, the required ion energy of many crucial implantation has been reduced to following degree: the conventional ion implant system of developing at first the ion beam much higher for generation of energy can't provide required implantation effectively.These extremely shallow knots are called " super shallow junction (Ultra-ShallowJunctions) " or USJ.

When extracting ion from ion source and transporting ion through the ion beam line of implanter subsequently, the limitation of conventional ion implant system in low ion beam energy situation is the most obvious.The ion extraction can be subject to the constraint of Child-Langmuir relational expression, and the Child-Langmuir relational expression shows: the ion beam current density of extracting is directly proportional to 3/2 power that extracts voltage (i.e. ion beam energy when extracting).Fig. 1 is the curve chart of relation between an expression maximum institute extraction arsenic ion beam electronic current and extraction voltage.For simplicity's sake, supposed in extracted ion beam and only existed ⁷⁵the As+ ion.Fig. 1 shows, when reducing energy, extracting electric current can reduce rapidly.In traditional Ion Implantation Equipment, find that the energy of this " extracting limited " mode of operation is lower than about 10keV.Also there is identical constraint when transporting low energy ion beam.The energy of ion beam is lower, and its gait of march is lower, thereby, for a set value of ion beam current, each ion can more be close to together, that is ion concentration can increase.This can be found out by relational expression J=nev, and wherein J is that (unit is mA/cm to ion beam current density ²), n is that (unit is cm to ion concentration ^-3), e is electron charge (=6.02 * 10 ^-19coulomb), v is average ion speed (unit is cm/s).Due to the electrostatic force between each ion and its spacing from square be inversely proportional to, therefore the repulsive interaction under low-yield is much better than, thereby this can make divergence of ion beam.This kind of phenomenon is called " ion beam amplifies (beam blow-up) ".Although in the ion beam line of implanter, existing low-energy electron stream tends to be caught by positively charged ion beam thereby contributes to the space charge during compensation transports to amplify, yet still there will be ion beam to amplify, and the most remarkable when having electrostatic focusing lens, because electrostatic focusing lens tends to divest the compensate for electronic with high mobility of loose combination in ion beam.The atom of laying particular stress on for arsenic (75 atomic mass units) etc., because ion velocity under a set ion energy can be slower than light atom, thereby transporting of low energy light beam may be very difficult.Also there is very large extraction and transport difficulty for P-type dopant boron.The implantation energy of extremely low (for example, lower than 1keV) that some forward position technique is required and the following fact transport boron and become very difficult: from a typical BF ₃the most of ion the non-required ion that extract in the plasma of source and transport ¹¹b ⁺, but fragment ion (19F for example ⁺and ⁴⁹bF ₂ ⁺), these fragment ions can increase the average quality of charge density and the ion beam that extracts.In the future that prospect VLSI semiconductor is manufactured, will together make the formation of USJ have challenge transporting existing these difficulties aspect large low energy As and B electric current.

A kind of equational method of above-mentioned Child-Langmuir of benefiting from is by by a molecular ionization that contains related dopant but not the dopant atom ionization is increased to mass of ion, and example as shown in Figure 1a.By this kind of mode, although the kinetic energy of molecule is larger during transporting, yet, when entering substrate, molecule can split into its constituting atom, thereby make molecular energy be distributed to distribute according to atomic mass by each atom, thus make the implantation energy of dopant atom initial far below it transport kinetic energy.Below consider a dopant atom " X " is bonded to a group " Y " (for the purpose of demonstration, no matter whether " Y " can affect this device, forming technique).If implanting ions XY ⁺but not implant X ⁺, XY ⁺extraction and transport energy must be higher, the increase coefficient of this energy equals { (quality of XY)/(quality of X) }; This speed that can guarantee X remains unchanged.Because the described space charge effect of Child-Langmuir equation hereinbefore is superlinearity for ion energy, thereby the maximum ion electric current that can transport can increase.In history, use polyatomic molecule to solve the practice that low energy implants problem for known to described technical field.One common example is to use BF when implanting low energy boron ₂ ⁺molecule replaces B ⁺.The method is by the unstrpped gas BF of institute ₃be dissociated into BF ₂ ⁺for implanting.By this kind of mode, mass of ion is increased to 49 atomic mass units, almost increase to 5 times (49/11) thereby make to extract and transport energy for using single boron atom.Yet, after implantation, the energy of boron can be reduced to identical multiple (49/11).We notice, because per unit electric charge in ion beam only has a boron atom, thereby this kind of method can not reduce the current density of ion beam.In addition, this kind of method also by fluorine atom with boron together in the implanted semiconductor substrate, yet people know, fluorine can show adverse effect to semiconductor device.

Also exist decaborane as polyatomic molecule for the atomic ion technique of implanted ions at present, as people such as Jacobson at " decaborane, a kind of alternative method (Decaborane implanted for ultra-low energy ion, an Alternative approach to Ultra Low Energy Ion Implantation) " (XIII international ion embedding technology meeting proceedings of the IEEE held at Austrian Alpsbach, 300-303 page (2000)) reach Yamada at " the gas ion beam is for the application (Applicationof gas cluster ion beams for material processing) of material processed " (Materials Scienceand Engineering A217/218, 82-88 page (1996)) in, report.In this kind of situation, the particle of implanting is decaborane molecule B ₁₀h ₁₄ion, it contains 10 boron atoms, thus be a boron atom " bunch ".This kind of technology not only can increase mass of ion, and due to decaborane ion B ₁₀h _x ⁺the per unit electric charge has ten boron atoms, thereby, for a set ionic current, it can enlarge markedly the implant dose rate.This is a kind of for forming USJ P-type metal oxide semiconductor (PMOS) transistor at silicon and generally speaking for implanting the technology that has prospect of utmost point low-energy boron.Significantly reduce the electric current (reducing a factor 10 when using decaborane ion) carried in ion beam and not only can reduce the space charge effect of ion beam, but also can reduce the disk charge effects.We know, bombarding the especially gate oxide charging of charging of caused disk by positive ion beam can reduce device yield by destroying responsive gate pole insulation, thereby by this current reduction very attractive for the USJ device manufacture that extremely low gate pole threshold voltage must be provided day by day of using ion beam to realize.It should be noted that in the example of implanting at these two P-type molecules, is by only by institute's raw material ionization but not form ion by institute's raw material is gathered to cluster.It shall yet further be noted that up to now, not yet develop a kind of compare favourably for making the technology of N-type molecular dopant ion.Complementary metal oxide semiconductors (CMOS) (CMOS) process future success may greatly depend on feasible N-type and whether P-type polyatom implanted prosthetics can obtain commercialization.Therefore, need to solve two obvious problems that semi-conductor industry faced now: the poor efficiency problem that disk charging problem and low energy ion are implanted.

In history, Ion Implantation Equipment is divided into to three basic forms of it: large electric current implanter, medium current implanter and high-energy implanter.And ion beam is applicable to large electric current and medium current is implanted technique.More specifically, current large electric current implanter is mainly used in forming transistorized low-yield, heavy dose of regional (for example drain electrode structure) and doped polycrystalline silicon gate pole.It typically is the batch processing implanter, that is it can process many disks that are installed on a rotating disk and ion beam keeps static.The high-current ion beam line is often simple and ion beam is had to large acceptance; Under low-yield and large current conditions, the ion beam at substrate place is often larger, has a large angular divergence.The medium current implanter comprises a succession (often next disk) process chamber usually, and it can provide a high dip function (for example from the substrate normal slope, reaching 60 degree).For guaranteeing the uniformity of dosage, usually with electromagnetic mode along orthogonal direction ion beam on whole disk.For meeting coml implant dosage uniformity and repeatable requirement (usually requiring only deviation a few percent), ion beam should have excellent angle and spatially uniform (for example even angle of ion beam<2 degree on disk).In view of these requirements, the ion beam that the medium current ion beam line is designed to provide excellent is controlled, but that cost is acceptance is limited.In other words, ion is subject to the restriction of ion beam emittance by the efficiency of transmission of implanter.At present, ion beam with the higher electric current of low (<10keV) power generation (about 1mA) in the succession implanter is a problem very much, for example cause, for some more low-energy implantation (while forming source electrode and drain electrode structure in CMOS technique ahead of the curve), the productivity ratio of disk can be low make us accepting.Under the low ion beam energy of each ion energy<5keV, for batch processing implanter (processing many disks of installing on a rotating disk), also there is same transport issues.

Transport Optical devices although can design almost aberrationless ion beam, yet ion beam characteristic (spatial dimension, spatially uniform, angular divergence and even angle) depend primarily on ion source self emittance character (i.e. ion beam character when extracting ion, its determined ion beam during from the ion source outgoing implanter Optical devices by ion beam focusing and the scope that controls to).Transport energy and reduce ion beam institute carries current and use ion beam to replace the monomer ion beam can improve ion beam, thereby obviously strengthen the outgoing of ion beam.Therefore, in semiconductor is manufactured, need a kind of cluster ion and cluster ion source technology, so that except more effective dose rate and higher productivity ratio are provided, also on target, provide one through better focusing, more collimation and stricter controlled ion beam.

Summary of the invention

One aspect of the present invention is to provide a kind of method of manufacturing semiconductor device, and the method can form the super shallow impurity doping region of (the being the acceptor) conductance that has the N-type in Semiconductor substrate, and is to form with high production rate.

Another aspect of the present invention is to provide a kind of implanted ions system and method, wherein with B ₁₀h _x ^-form produce electronegative decaborane (B ₁₀h ₁₄) ion it is implanted in semi-conductive substrate and forms p-n junction.

Another object of the present invention is to provide a kind of method of manufacturing semiconductor device, and the method can be used As ₀h _x ⁺form (for N-type bunch, wherein n=3 or 4 and 0≤x≤n+2) and B ₁₀hx ⁺or B ₁₀hx ^-the N-type of form (for P-type bunch) and P-type bunch form N-type or the super shallow impurity doping region of P-type (being acceptor or alms giver).

Another purpose of the present invention is to provide a kind of implantation As ₃hx ⁺and As ₄hx ⁺the method of the arsenic cluster ion of form, the method can form super shallow implantation zone of N conductivity type in semi-conductive substrate.

Another purpose of the present invention is to provide a kind of P that makes in the following way _nh _x ⁺form (wherein n equal 2,3 or the scope of 4, x in 0≤x≤6 in) the method for phosphorus cluster ion: by PH ₃the unstrpped gas ionization, implant this phosphorus bunch in semi-conductive substrate subsequently to complete the doping of N-type.

Another purpose of the present invention is to provide a kind of B that makes in the following way _nh _x ⁺form (wherein n equal 2,3 or the scope of 4, x in 0≤x≤6 in) the method for boron cluster ion: by B ₂h ₆the unstrpped gas ionization, implant this boron bunch in semi-conductive substrate subsequently to complete the doping of P-type.

A further object of the present invention is to provide a kind of implanted ions system be used for producing the semiconductor devices, and it has been designed to form in semi-conductive substrate with cluster ion the super shallow impurity doping region of N or P conductivity type.

According to an aspect of the present invention, a kind of method of implanting cluster ion is provided, it comprises the steps: to provide a dopant atom or molecular source in a chamber, by dopant atom or group of molecules synthetic contain some dopant atoms bunch, these dopant cluster ions are changed into to the dopant cluster ion, use an electric field extract the dopant cluster ion and make its acceleration, ion beam is carried out to quality analysis, then the dopant cluster ion is implanted in semi-conductive substrate.

An object of the present invention is to provide a kind of following method: by implant one by n dopant atom (at As ₄hx ⁺n=4 in situation) form bunch but not implant a single atom at every turn, make manufacturers of semiconductor devices can improve the difficulty existed when extracting low energy ion beam.Due to bunch in each atom all with the energy of an E/n, implant, thereby this kind of cluster ion method for implantation provides the equivalent method of low-yield monatomic implantation.Therefore, implanter is extraction voltage power supply doubly with the high n of a more required implantation energy, and this can realize higher ion beam current, is especially forming under the required low implantation energy of USJ.Consider the ion extraction stage, by estimation Child-Langmuir limit value, can implant the relative improvement realized to cluster ion and be quantized.It should be understood that but this limit value approximate representation is:

(1)J _max＝1.72(Q/A) ^1/2V ^3/2d ^-2，

J wherein _maxunit be mA/cm ², Q is charge states, and A is mass of ion (unit is AMU), and V is for extracting voltage (unit is kV), and d is gap width (unit is cm).Fig. 1 one is being used ⁷⁵as ⁺and the curve chart of equation in the d=1.27cm situation (1).In practice, can make many implanted ions agent extraction Optical devices used approach this limit value.By expansion equation (1), can define following index and count Δ, so that cluster ion is implanted and is quantized with respect to the productivity ratio of monatomic implantation or the increment of implant dose rate:

(2)Δ＝n(U _n/U ₁) ^3/2(m _n/m ₁) ^-1/2.

Herein, Δ be with energy U ₁(U wherein ₁=eV) carrying out a quality is m ₁the monatomic implantation of atom compare, with an energy U _nimplant one have n related dopant atom bunch the time dose rate (atom/second) that obtains relative raising amount.If adjust U _nmake the dopant implantation depth identical with monatomic (n=1) situation, equation (2) is reduced to:

(3)Δ＝n ²。

Therefore, implant a bunch dose rate provided formed by n dopant atom likely than traditional high n of monatomic implantation ²doubly.At As ₄hx ⁺in situation, for little x, this PDR raising amount is about 16 times.Fig. 2 has shown low energy As and As ₄comparison between implantation, to be explained this.

Use bunch is carried out implanted ions and also can be solved the transport issues of low energy ion beam.It should be noted that cluster ion implantation technique only requires each cocooning tool that an electric charge is arranged, but not as made each dopant atom all with an electric charge in conventional situation.Because the diversity Coulomb force can reduce along with the reduction of charge density, thereby this can improve and transports efficiency (beam transmission).In addition, the quality of ion cluster, higher than monomer whose, therefore more is not vulnerable to the impact of Coulomb force in ion beam.Therefore, use by n dopant atom, formed bunch but not use single atom to carry out implantation and can improve the basic transport issues of low energy ion in implanting, and realize the obvious higher technique of a productivity ratio.

For realizing the method, need to form described cluster ion.With producing monomer, compare, in commercially available Ion Implantation Equipment, conventional source used only produces a small part be mainly lower-order (for example n=2) bunch, thereby these implanters can't realize above that listed low energy ion beam implants advantage effectively.In fact, the strong plasma that many conventional ion source provides is by molecule on the contrary and bunch is dissociated into its Constitution Elements.And novel ion source as herein described is owing to having used one " soft " ionization technique (the electronic impact ionization of being undertaken by the high energy primary electron), thereby can produce sufficient cluster ion.Ion source of the present invention clearly is designed for and produces and maintain the dopant cluster ion.

The accompanying drawing explanation

To be easy to understand these and other advantage of the present invention with reference to hereinafter explanation and accompanying drawing, in accompanying drawing:

Fig. 1 is that a demonstration is according to Child-Langmuir law maximum ⁷⁵as ⁺the curve chart of relation between ion beam current and extraction energy;

Fig. 1 a is that a demonstration can be by the curve chart of the contrast between the maximum extracted electric current of tetramer arsenic and the acquisition of monomer arsenic;

The simplicity of illustration that Fig. 2 is cluster ion source of the present invention;

The stereogram of the example embodiments that Fig. 2 a is cluster ion source of the present invention;

The side sectional view that Fig. 2 b is an ionogenic part shown in Fig. 2 a, it is superimposed with electron beam and magnetic field above showing ion source;

Fig. 2 c be shown in the three-dimensional cutaway view of an ion source part, it shows according to magnetic field of the present invention and electron beam source;

The vertical view of the simplification that Fig. 2 d is the ionogenic electron beam forming area of the present invention territory;

The calcspar that Fig. 2 e is a temperature control system that can be combined with the present invention;

The simplicity of illustration that Fig. 3 is an exemplary cluster ion implant system of the present invention;

Fig. 4 a one is presented at and forms the graphic of a CMOS manufacturing sequence during the NMOS drain extension;

Fig. 4 b one is presented at and forms the graphic of a CMOS manufacturing sequence during the PMOS drain extension;

Fig. 5 is the graphic of semi-conductive substrate in the technique of manufacturing the NMOS semiconductor device, and it is in N-type drain extension implantation step;

Fig. 5 a is the graphic of semi-conductive substrate in the technique of manufacturing the NMOS semiconductor device, and it is in the source/drain implantation step;

Fig. 5 b is the graphic of semi-conductive substrate in the technique of manufacturing the PMOS semiconductor device, and it is in P-type drain extension implantation step;

Fig. 5 c is the graphic of semi-conductive substrate in the technique of manufacturing the PMOS semiconductor device, and it is in the source/drain implantation step;

Fig. 6 is the PH that a demonstration is produced by ion source of the present invention ₃mass spectral:mass spectrographic graphic;

Fig. 7 is the AsH that a demonstration is produced by ion source of the present invention ₃mass spectral:mass spectrographic graphic;

Fig. 8 is the As in low energy range on a demonstration disk ₄h _x ⁺the schematic diagram of ionic current;

Fig. 9 is the schematic diagram that a demonstration converts the described data of Fig. 6 of ion beam brill to;

Figure 10 is that a use the present invention is by AsH _x ⁺and As ₄h _x ⁺after in ion beam implanted silicon disk, the curve chart that the arsenic concentration SIMS that implanted distributes, and with the contrast of TRIM result of calculation;

Figure 11 is the B that use ion source of the present invention produces ₂h ₆mass spectral:mass spectrographic curve chart;

Figure 12 one is used the curve chart of the positive ion mass spectrum recorded in decaborane raw material situation in the present invention;

Figure 13 one is used the curve chart of the negative ion mass spectrum recorded in decaborane raw material situation in the present invention;

Figure 14 is the two mass spectral:mass spectrographic curve chart of a continuous recording anion and cation decaborane, and also shows dimer B ₂₀h _x;

Figure 15 is that a use the present invention implants at the decaborane of 20keV the negative B implanted under energy ₁₀h _xion and positive B ₁₀h _xthe curve chart that the SIMS of ion distributes;

Figure 16 one has implanted the curve chart that SIMS distributes while implanting the 20keV decaborane in silicon, and it shows B concentration and H concentration;

Figure 17 is an expression ionization cross section sigma and ammonia (NH ₃) electron energy T between the curve chart of functional relation;

Figure 18 is the mass spectrum of the positive decaborane ion of use ion source generation of the present invention;

Figure 19 is the mass spectrum of the negative decaborane ion of use ion source generation of the present invention.

Embodiment

A plurality of embodiment of the present invention hereinafter will be provided.These embodiment relate to and manufacture various N-types and P-type dopant cluster ion and electronegative ion beam.The two all can produce N-type and P-type dopant cluster ion and electronegative ion beam with the ion source shown in Fig. 2-2e.

Fig. 2-2e shows the concept map of a cluster ion source 10 and each assembly thereof.At first referring to Fig. 2, provide a unstrpped gas source of supply 11, for example one bottle of AsH ₃, PH ₃, B ₂h ₆or vaporized B ₁₀h ₁₄.Raw material can at room temperature be stored in a gas cylinder with gas form, or can be used as from a heated solids distillation or introduce from the steam form of a liquid phase volatilization.Unstripped gas body source 11 is connected to a chamber 13 by a flow controller 12.Flow controller 12 both can be accurate to one by computer-controlled mass flow controller, also can be simply to a tube connector with a predetermined gas conducting amount.Under latter event, by the gas pressure of controlling in 11, change flow.Controlling can be at the stable air pressure of the interior formation one of chamber 13 containing the raw-material flow of gaseous state of dopant, and for example this air pressure is between approximately 3 * 10 ^-4torr and 3 * 10 ^-3between torr.Ionization energy 14 is to provide with a form with controlled electron stream of a predetermined energy or speed.Usually, the temperature of chamber 13 and in fact ionogenic all component is all controlled to a desirable value.By source pressure, temperature, electron stream and electron energy are regulated, can be at interior formation one environment of chamber 13, this environment makes AsH ₃dopant atom or molecular combinations form and contain the cluster ion more than a required dopant element atom, for example tetramer compd A s ₄h _x+, wherein x is an integer between 0 and 4.

A hole 17 in chamber 13 can escape in ion beam path ion, then by chamber 13 and a highfield extracted between electrode 15, is extracted.This extraction or accelerating field are produced by a high-voltage power supply, this high-voltage power supply by chamber 13 relatively current potential be biased into a voltage V, wherein extract closely current potential of electrode 15.This accelerating field can attract cation go out chamber 13 when setting up forward, and, when expectation obtains anion, on oppositely, sets up this accelerating field.Extracting electrode 15 makes the ion through accelerating form an ion beam 16.The kinetic energy of ion beam 16 is meaned by equation (14):

(4)E＝/qV/。

The current potential that wherein V is source, the electric charge that q is each ion.When V with volt mean, q is while meaning with the unit of charge, the unit of E is electronics-volt (eV).

The ion source that forms the part of implanted ions system of the present invention is an electronic impact formula ion source.Fig. 2 a is the ionogenic generalized section of a present invention, and it shows structure and the function of each assembly that forms ion source 10.This section is to dissect along a plane that comprises the ion beam direction of propagation, thereby by ion source in two.Ion source 10 is included in a gasifier 28 and the ion beam that mounting flange 36 places combine and forms zone 12.Ion source 10 is made as by a mounting flange 36 and is situated between and connects find time vacuum chamber or the gas technology instrument of an Ion Implantation Equipment.Therefore, the part in flange 36 right sides in Fig. 2 a intermediate ion source 10 is in high vacuum state (pressure<1 * 10 ^-4torr).Gaseous material is introduced in a chamber 44, therein by from the electronic impact of one or more electron beam 70a and 70b by the gas molecule ionization, wherein one or more electron beam 70a and 70b enter chamber 44 by a pair of opposed electron beam inlet hole 71a and 71b.Use this structure, can form ion at the ion extraction aperture 81 places near in a ion extraction orifice plate 80.Then, use an extraction electrode (not shown) that is positioned at the ion extraction orifice plate 80 fronts to extract these ions and it is formed to a high energy ion beam.

There are various gasifiers 28 to be applicable to the present invention.One exemplary gasifier 28 is shown in Fig. 2 a.This gasifier 28 is an exemplary gasifier, and it can be by a gasifier body 30 and for example, for carrying Solid Source raw material 29 (decaborane B ₁₀h ₁₄) crucible 31.Resistance heater can embed in gasifier body 30.Water-cooling groove 26 and convection type air cooling groove 27 can be configured to close contact gasifier body 30, are used to crucible 31 that a uniform working temperature higher than room temperature is provided.Heat conduction between the gasifier body 30 that crucible 31 and temperature are controlled is to realize by gases at high pressure of being introduced in one crucible-this body interface of gasifier 34 by a gas supply source 41, and the temperature of gasifier body 31 is monitored by a thermocouple.Decaborane B after gasification ₁₀h ₁₄or other gasification materials 50 are collected in a headroom, crucible town 51, and, after the steam conduit 32 in through gasifier outlet opening 39, through a pair of isolating valve 100 and 110,, being contained in a source piece 35, by a vapour inlet hole 33, enter chamber 44.Also can by isolating valve 100,110, mounting flange 36, and the temperature of source piece 35 control to being close to or higher than the gasifier temperature, in case steam condensing.

The ion source plenum system can comprise from two independent sources being two conduits of chamber 44 air feed.First source can be one and has the low conductive path of minor diameter, for for example, from a high-pressure air source (gas cylinder (not shown)) gaseous state raw material.Second source can be from a high conductance path from a low temperature gasification device.Regardless of source of the gas, this plenum system all can maintain one and for example count the air pressure of milli torr in chamber 44.Gasifier 28 keeps strict temperature to control to the surface of its contact solid-state material so that flow into the gas flow of chamber keep stable and and then in this indoor maintenance stable pressure.

Before maintenance gasifier 28, isolating valve 110 can cut out so that ion source and Ion Implantation Equipment remain in vacuum state.Also isolating valve 100 can cut out so that steam 50 keeps being contained in crucible 31.Then, gasifier 28 can be transported to a chemical cleaning tank safely, crucible 31 is feeded or cleaned.Before Open valve 100, can open an intrinsic ventilation valve 111 that is soldered to valve 100 so that between crucible empty under atmospheric pressure.Once overhaul complete, get final product valve-off 100 again, and by valve 100 being connected to valve 110, gasifier 28 is mounted on ion source 10, then ventilation valve 111 is connected to a roughing line, extract vacuum out with the dead space by between crucible 31 and valve 100 and valve 110.Then, can open when needed isolating valve 110, this can not destroy the vacuum environment of ion source and Ion Implantation Equipment.

One gasifier assembly 30a is heated by one and formed by cooling body 30 and a movable crucible 31.Can touch crucible 31 by an end plate (not shown) of removing on gasifier 28 backs.After autopneumatolysis device 28 moves lower crucible 31, can be sealed to the crucible cover 34b of crucible end and mention one for isolating the comb grid of solid 29 by removing with elastomeric material, crucible 31 is feeded again.After charging again, crucible 31 is inserted in gasifier bodies 30 and the outlet opening 39 in gasifier body 30 fronts is carried out to vacuum seal, so that headroom, crucible town 51 is isolated with the heat-conducting gas be present in this body interface of crucible-gasifier 34.For realizing the temperature homogeneity of crucible 31, crucible 31 coordinates for closely cooperating with the machinery between gasifier body 30.Any gap between crucible 31 and gasifier body 30 all can be filled with gas, is beneficial to the heat transmission between these two surfaces.Heat-conducting gas enters described gap by an end plate joint 28a, and can in or approach atmospheric pressure.

Can use (for example) to implement temperature to ratio-integral differential (PID) closed-loop control that can be embedded in the resistive element in gasifier body 30 controls.Fig. 2 e shows the calcspar of a preferred embodiment, wherein defines three temperature provinces: corresponding to the zone 1 of gasifier body 30, corresponding to the zone 2 of isolating valve 100 and 110, reach the zone 3 corresponding to source piece 35.Each zone all can have a nonshared control unit, for example an Omron E5CK digitial controller.In the simplest situation, heating element self for example, for controlling on one's own initiative temperature higher than room temperature, between 18 ℃ and 200 ℃.Therefore, the cartridge type resistance heater can be embedded in gasifier body 30 (heaters 1) and source piece 35 (heater 3), valve 100,110 can be wound around with silicone band heater (heater 2, wherein resistive element is silk or foil) simultaneously.Three thermocouples (being designated TC1 in Fig. 2 e, TC2 and TC3) can be embedded in each assembly in these three assemblies 30,35,100, and each temperature controller in three special-purpose temperature controllers reads continuously.Temperature controller 1,2 and 3 respectively by user program to temperature set-point SP1, SP2 and SP3.In one embodiment, these temperature set-points must make SP3>SP2>SP1.For example, if expectation makes the gasifier temperature, be 30 ℃, SP2 can be 50 ℃, and SP3 can be 70 ℃.The working method of controller is generally: when TC value of feedback and set point, when inconsistent, the comparator of controller can start cooling or heating operation as required.For example, if only with heating, change temperature, if not TC1<SP1, comparator output will be zero.Controller can comprise one and use table about looking into of the nonlinear function between power output and temperature difference SP1-TC1, and presents suitable signal to the heater power source of controller, so that temperature is adjusted to the set-point value of being programmed smoothly.A kind of usual method that changes heater power is that power supply is carried out to pulse-width modulation; This kind of technology be used in full scale 1% and 100% between carry out power adjustments.These PID controllers can remain on temperature set-point (deviation) in 0.2 ℃ usually.

For keeping temperature homogeneity, the gasifier bulk material that can select to have high-termal conductivity.Can use air groove on the outer surface that is positioned at gasifier body 30 wittingly gasifier body 30 to be applied to a little heat leak (Fig. 2 a), to improve stability of control system and to reduce the sedimentation time.Air groove 27 hides around gasifier body 30 and by plate (not shown).Can air be delivered to one by conduit and be integrated in each groove in collecting pipe system in end plate 38, cooling so that appropriate Continuous convective to be provided.Air is being sent into by entrance after for the metering valve of controlling flow through one.Finally, air enters the room exhaust outlet from the air assembly.

Outside deacration is cooling, also can take measures to carry out gasifier body 30 with liquid.For example, can be that cooling agent is carried with pipeline in 6mm and the aperture of running through back and forth gasifier body 30 by one for example 1 meter long, diameter.Can be connected by the joint be mounted on body port 26.Liquid cools can make the gasifier assembly cooling fast, thereby the time between overhauls(TBO) fast can be provided when needed.

Can gas feed be entered in chamber 44 by a gas conduit 33 (for example, from a gas cylinder).As described above, solid-state raw material can gasify in gasifier 28, and then, steam can be fed in chamber 44 by steam conduit 32.As described above, the temperature control of gasifier body 30 can make the solid-state raw material 29 that are positioned at porous segregator barriers 34a below remain in a constant temperature.The steam 50 gathered in headroom, town 31 was presented boring 39 and break valve 100 and 110, then by the steam conduit 32 that is arranged in source piece 35, was fed into chamber 44.Therefore, gaseous state and the solid-state material with dopant all can obtain ionization by this ion source.

Fig. 2 b is a side sectional view, and it shows the basic optical design of a multi electron beam ion source structure of the present invention.In one embodiment of this invention, a pair of be heated white-hot filament 110a and the 110b spatially separated launches a pair of electron beam 70a and the 70b spatially separated, this to electron beam 70a and 70b bundle guide field or magnetostatic field B 135a and 135b (along one perpendicular to shown in the direction of paper plane) effect under, at first through substrate 105a and the 105b of a pair of substrate aperture 106a and 106b and pair of spaced, then through pair of electrons are, enter perforation 71a and 71b enters chamber 44 along one 90 degree tracks.One tunnel bends towards a pair of reflector barricade 102a and 102b through the electronics of chamber 44 (through electron impact hole 71a and 71b the two) under the effect of bundle guide field or magnetostatic field 135a and 135b.When electron beam 70a and 70b propagate through substrate aperture 106a and 106b, by applying a voltage Va to substrate 105a and 105b (being provided by forward power supply 115) and applying voltage Ve to white-hot filament 135a and 135b (being provided by negative sense power supply 116), electron beam 70a and 70b were slowed down before injecting chamber 44.In ion beam forms and transports zone, (outside chamber 44) makes electron beam energy keep fully most important higher than carrying out the common required energy of ionization, this is because in more low-yield situation, and space charge effect can seriously reduce beam electronic current and increase beam diameter.Therefore, in this zone, expectation remains between 1.5keV and 5keV electron beam energy.

All voltage all be take chamber 44 as benchmark.For example, if Ve=-0.5kV and Va=1.5kV, the energy meter of electron beam is shown e (Va-Ve), and wherein e is electron charge (6.02 * 10 ^-19coulomb).Therefore, in this example, electron beam 70a or the 70b energy when formation and deflection is 2keV, but is entering electron impact hole 71a, and after 71b, its energy is only 0.5keV.

Following table has provided the approximation that makes the required magnetic field B of crooked 90 degree of electron beam that an energy is E.

table 1

Be to realize the magnetic field intensity of 90 degree deflections need and the relation of electron energy in the present invention

Electron energy E magnetic field B

1500eV	51G
		2000eV	59G
2500eV	66G

Other important documents shown in Fig. 2 b comprise extracted ion beam 120, a source electrostatic screen plate 101, reach a pair of reflector barricade 102a and 102b.These reflector barricade 102a and 102b have two kinds of purposes: shield electromagnetic and shielding stray electron or ion beam.For example, reflector barricade 102a and 102b can make electron beam 70a and 70b avoid the impact of the field that is associated with potential difference between source barricade 101 with substrate 105a and 105b, and also as the stray electron bundle from opposed electronic emitter, dump ground.The impact that 101 of source barricades make ion beam 120 not produced by potential difference between substrate 105a and 105b and chamber 44, and also for absorbing stray electron and ion, otherwise these stray electrons and ion can affect the ion source important document.For this reason, reflector barricade 102a and 102b and source barricade 101 the two for example, by refractory metal (molybdenum or graphite), make.Perhaps, can ion beam 120 be shielded and come more up hill and dale with magnetic field B 135a and 135b by for example, made source barricade 101 by a ferromagnetic substance (magnetic stainless steel).

The cutaway view that Fig. 2 c is a demonstration mechanical detail, it clearly shows how content integration shown in Fig. 2 b is entered shown in Fig. 2 a in ion source.Wherein, by one or more white- hot filament 110a and 110b, with thermion mode electron emission, these electronics accelerate to move to the anode of a pair of correspondence, form thus electron beam 70a and 70b.This structure can provide some advantages.At first, white- hot filament 110a and 110b both can work respectively and also can work together.Second; because electron beam is in the outside generation of chamber; thereby the life-span of reflector with respect to known configuration, extended, this be because reflector in staying the environment under low pressure there is ionogenic implanter vacuum chamber and reflector also effectively be subject to anti-Ions Bombardment protection.

Form the bundle guide field from the magnetic flux of pair of permanent magnets 130a and 130b and a pair of magnetic pole assembly 125a and 125b, at electron beam the air gap two ends between the magnetic pole assembly end of wherein propagating set up uniform magnetic field.The matching way of the electron beam energy of magnetic field 135a and 135b and electron beam 70a and 70b must make electron beam 70a and 70b partially turn 90 degrees as shown in the figure and enter in chamber 44. Make electron beam 70a and 70b deflection for example 90 the degree after, can not have sight line between reflector and chamber, can prevent that thus reflector is subject to the bombardment of high energy charged particles.

Because Va is positive voltage with respect to chamber 44, thereby electron beam 70a and 70b can slow down when the gap through being defined by substrate aperture 106a and 106b and electron impact hole 71a and 71b.Therefore, substrate aperture 106a and electron impact hole 71a, and substrate aperture 106b and electron impact hole 71b, and the combination in gap therebetween, form respectively an electrostatic lens, forms in this example a retarding lens.Use retarding lens, can make people can regulate the ionization energy of electron beam and generation and deflection that can the appreciable impact electron beam.

This gap can be set up by one or more ceramic space sheet 132a and 132b, ceramic space sheet 132a and 132b support each substrate 105a and 105b and as one with the bearing isolated in the source of chamber current potential piece 35.Ceramic space sheet 132a and 132b not only provide electric insulation but also provide mechanical support.It should be noted that for clarity sake not shown reflector barricade 102 and source barricade 101 in Fig. 3.

Because electron impact hole 106a and 106b can limit passing of electron beam 70a and 70b, thereby substrate 105a and the 105b part that can tackle high-power electron beam 70a and 70b.Therefore, substrate 105a and 105b must be subject to active cooling or passive cooling.Active cooling can for example, be realized by making liquid coolant (water) flow through substrate.Perhaps, can by allow substrate reach one its can, by its ambient radiation, obtaining cooling temperature, realize passive cooling.This steady temperature depends on the power of tackled electron beam, the surface area of substrate and the temperature of emissivity and peripheral components.For example, when using condensable gas (decaborane steam), allowing that substrate 105a and 105b work at elevated temperatures may be better, because condensable gas can form the film that has contaminative and can form particle on low-temperature surface.

Fig. 2 d shows the vertical view of the simplification in this ionogenic electron beam forming area territory.The relative chamber 44 of white-hot filament 110b is in current potential Ve, for example-0.5keV, and anode 140b, magnetic pole assembly 125b, substrate 150b, and reflector barricade 102b all in anode potential Va, 1.5keV for example.Therefore, electron beam energy is 2keV.Electron beam 70b can the air gap between the magnetic pole of magnetic pole assembly 125b in deflection under the effect of magnetic field 135b, thereby make electron beam 70b through substrate aperture 106b.The representative diameter value of substrate aperture 160a and 160b and electron impact hole 71a and 71b is respectively 1cm.

Fig. 3 shows that this ion source forms a cluster ion implant system proposed by the invention with together with crucial downstream components.Also can adopt and be different from the structure shown in Fig. 3.Wherein ion source 21 couples and extracts electrode 22, to form an ion beam that contains cluster ion 20.Ion beam 20 contains the ion all substances of the ion with a set charge polarity (that is can form for it in ion source 21) of many kinds of different qualities usually.Then, ion beam 20 is injected analyzing magnet 23.Analyzing magnet 23 forms a dipole magnetic field in the ion beam transport path according to the electric current in magnet coil; The direction in this magnetic field is perpendicular to plane shown in Fig. 3.The function of analyzing magnet 23 is to depend on the quality of each single ion by ion beam being curved to its radius: the circular arc of charge ratio spatially is divided into the thin ion beam of a group component by ion beam.This circular arc is shown as an ion beam component 24, i.e. desired ion bundle in Fig. 3.Magnet 23 can make a set ion beam along one by the radius bend shown in following equation (5):

(5)R＝(2mU) ^1/2/qB

Wherein R is bending radius, and B is magnetic flux density, and m is mass of ion, and U is ion kinetic energy, the state of charge that q is ion.

Selected ion beam only consists of quality-narrower ion of energy product scope, so that the bending radius of ion beam under the magnet effect makes this ion beam through a quality discrimination hole 27.In ion beam, not selected component can not pass this quality discrimination hole 27, but is tackled in other positions.For quality: charge ratio m/q is less than the ion beam 25 (hydrogen ion that is for example 1 or 2 atomic mass unit by quality forms) of selected bundle, magnetic field can induce a less bending radius, thereby makes this ion beam intersect at inner diameter wall 30 or other positions of magnet room.For quality: charge ratio is greater than the ion beam 26 of selected ion beam, and magnetic field can induce a larger bending radius, thereby makes outside diameter wall 29 or other positions of this ion beam strikes magnet room.Well-known in affiliated technical field, analyzing magnet 23 constitutes a quality analysis system with quality discrimination hole 27, and it selects ion beam 24 for the bundle of the many substance ions from extracting from ion source 20.Then, can make selected ion beam 24 through a post-analysis acceleration/deceleration level 31.This level 31 can be adjusted to ion beam energy the desired required final energy value of concrete implantation technique.For example, post-analysis acceleration/deceleration level 31 can be the form of an electrostatic lens or a LINAC (linear accelerator).Differentiating that the ion that lives through charge-exchange or neutralization reaction (thereby not having correct energy) between hole and disk is transmitted to disk, can be incorporated into " neutral beam filter " or " energy filter " in this ion beam path for preventing those.For example, in the ion beam path that post-analysis acceleration/deceleration level 31 can be limited to follow because of a DC electromagnetic field applied at selected ion beam 24, comprise " broken line (dogleg) " or a small angle deflection; Become neutrality or will not affirm and can follow this path with the ion beam component of a plurality of electric charges.Then, as shown in Figure 3, the ion beam of process energy adjustment enters the ion beam scanning systems 32 in implant system.These ion beam scanning systems 32 these ion beams of scanning, so that whole target 28 is subject to even implantation.Can use various structures, for example use one dimension or bidimensional scanning system, reach static behaviour-magnetic scanning system.

Then, ion beam enters the also disk process chamber 33 in the high vacuum environment, and clashes into herein target 28.Disk process chamber and disk delivery system can have various structures, and main structure classes is sequential (often next disk) or batch-type (together processing many disks on a rotating disk).In the sequential process chamber, mechanically along the scanned ion beam of a dimension (horizontal or vertical), ion beam scans with electromagnetic mode on orthogonal direction, to guarantee implant, has preferably spatially uniform usually.In the batch-type system, the rotation of rotating disk can radially provide mechanical scanning, also carries out vertically or the scanning of horizontal direction, and it is static that ion beam keeps simultaneously.

Implant for cluster ion, arrange for accurate dopant is provided, need to make n contained in an ion cluster dopant atom all with identical kinetic energy, infiltrate substrate; In the simple case that molecular ion is An+ (that is it consists of uniquely n dopant atom A) form therein, each atom in this n dopant atom all must receive the 1/n of this ion cluster energy in infiltrating Semiconductor substrate the time in the same manner.For example, Sze exists the VLSI technology( vLSI Technology, McGraw Hill, 253-254 page (nineteen eighty-three)) in confirmed, when a polyatomic molecule clashes into a solid-state target surface, all there will be this kind of energy in part phenomenon.In addition, the electrical result of this kind of implantation need to be implanted identical with the equivalence of using monatomic implanted ions to carry out.These results are shown in " decaborane; a kind of alternative method (Decaborane; an Akternative approach to Ultra Low EnergyIon Implantation) of implanting for ultra-low energy ion " (XIII international ion embedding technology meeting proceedings of the IEEE held at Austrian Alpsbach in detail by people such as Jacobson, 300-303 page (2000)), for the situation of using decaborane to be implanted, set forth, in fact, estimate all can obtain identical result for any dopant bunch.

During implanted ions, dopant atom may deeper infiltrate in Semiconductor substrate by tunnelling (along symmetry direction or " tunnel " that contains a low lattice atoms density, entering substrate lattice).If ion trajectory overlaps with the direction of a passage in semiconductor lattice, ion can not collide substrate atoms substantially, thereby can enlarge the bombardment scope of dopant.A kind of is to form an amorphous layer on substrate surface for limiting the effective ways that even prevent tunnelling.A kind of method that forms this one deck is to implant the ion that the element ion identical with the Constitution Elements of substrate or implantation have same electrical character (from the same hurdle in periodic table) in substrate, so that the crystal damage that this implantation process causes is enough to eliminate crystal structure and the electrical property of change substrate in activating step subsequently not of the layer at substrate surface place.For example, can be in silicon substrate with the energy, 5 * 10 of 20keV ¹⁴cm ^-2dosage implanted silicon or germanium, to form this amorphous layer in silicon substrate, re-use subsequently cluster ion and implant and carry out shallow doped layer implantation.

One important application of this kind of method is the part as the CMOS manufacturing sequence, with cluster ion, implants to form N-type and P-type shallow junction.CMOS is the main digital integrated circuit technology of using at present, its namelist be shown on same chip form N-raceway groove and P-channel MOS transistor the two (complementary ( complementary) MOS:N and P the two).The successful part of CMOS is, circuit designers can utilize contrary transistorized complementary character to form better circuit, especially forms the active power the drawn circuit lower than other technologies.It should be noted that term N and P be based on negativity ( negative) and positivity ( positive) (N-type semiconductor has the negativity majority carrier, and vice versa), and if each regional type (polarity) of reversing, N-raceway groove and P-channel transistor are by mutually the same.Manufacture the transistor of two types and require sequentially to implant a N-type impurity and then implant a P-type impurity on same substrate, use the device of a photoresist screen protection another type simultaneously.It should be noted that each transistor types all requires the zone with two kinds of polarity correctly to work, but implant and the transistor of formation shallow junction are same type: the shallow implant of N-type forms the N-raceway groove, and the shallow implant of P-type forms the P-raceway groove.An example of this technique is shown in Fig. 4 a and Fig. 4 b.Particularly, Fig. 4 a shows a kind of method of passing through a N-type bunch implantation 88 formation N-channel drain zones of extensibility 89, and Fig. 4 b shows that passing through a P-type bunch implants 91 formation P-channel drain zones of extensibility 90.The two all requires to have the shallow junction of same structure to it should be noted that N-type and P-transistor npn npn, thereby has both used the N-type also to use bunch implantation of P-type to be conducive to form the advanced CMOS structure.

Fig. 5 shows that this kind of method is at an application example of making in the nmos pass transistor situation.This figure shows the Semiconductor substrate 41 after some the front end fabrication process step that has experienced more than half conductor devices.This structure is comprised of a N-type Semiconductor substrate 41, and this Semiconductor substrate 41 is processed through following steps: P-trap 43, channel insulation 42 and gate stack form 44,45.P-trap 43 forms a knot with N-type substrate 41, and this transistor of becoming in trap provides junction isolation.42 of channel insulations provide horizontal dielectric insulation in (in whole CMOS structure) between N-trap and P-trap.Then, make the gate stack that comprises gate oxide 44 and polysilicon gate electrode 45, for forming the transistor gates lamination, gate oxide 44 and polysilicon gate electrode 45 have passed through patterning.In addition, also applied photoresist 46 and, by its patterning, so that expose corresponding to the zone of nmos pass transistor, other zones in substrate are subject to the protection of photoresist layer 46.Now, in this technological process, substrate has performed drain extension and has implanted preparation, and it is device fabrication the most shallow required doped layer that drain extension is implanted.0.13 the typical process of the forward position device of μ m technology node require be arsenic implant energy between 1keV and 2keV, the arsenical amount is 5 * 10 ¹⁴cm ^-2.Then, making ion beam 47 (is As in this example ₄h _x ⁺) the directive Semiconductor substrate, usually must make the direction of propagation of ion beam perpendicular to substrate, in order to avoid be subject to the concealment of gate stack.As ₄h _x ⁺bunch energy should be required As ⁺implant energy four times, for example, between 4keV and 8keV.Ion cluster when clashing into substrate from solution, then dopant atom static in approaching the shallow-layer of semiconductor substrate surface under, this shallow-layer forms drain extension 48.It should be noted that the superficial layer of identical implant meeting access door electrode 49, for gate electrode provides extra doping.Therefore, the important application that the described technique of Fig. 5 is method proposed by the invention.

Another example of the method is shown in Fig. 5 a: form dark source/drain regions.This figure shows that Semiconductor substrate shown in Fig. 5 41 has lived through other process for fabrication of semiconductor device steps.These other processing steps comprise: form a pad oxide 51 and form wall 52 on the sidewall of gate stack.Now, apply a photoresist layer 53 and by its patterning, the transistor (being nmos pass transistor in this example) that the exposure wish of take is implanted.Next, implement implanted ions, form source electrode and drain region 55.Because this implant to require to be implanted with low-yield, heavy dose, thereby it be that one of bunch implantation method proposed by the invention is appropriately applied.0.13 the typical case of μ m technology node implants parameter and is about: 6keV/ arsenic atom (54) and 5 * 10 ¹⁵cm ^-2the arsenical amount, thereby it need to carry out a 24keV, 1.25 * 10 ¹⁵cm ^-2as ₄h _x ⁺implant, or a 12keV, 2.5 * 10 ¹⁵cm ^-2as ₂h _x ⁺implant, or a 6keV, 5 * 10 ¹⁵cm ^-2as ⁺implant.As shown in Figure 5, implant and can form source electrode and drain region 55 by this.These zones can each circuit interconnection line (will follow-up formation in this technique) with define between the intrinsic transistor formed and provide a high conductivity to be connected in conjunction with channel region 56 and gate stack 44,45 by drain extension 48.It should be noted that gate electrode 45 can be exposed to this implantation (as shown in the figure), if be really that so the source/drain implant can provide main doped source for gate electrode.In Fig. 5 a, this is shown as multiple doped layer 57.

Fig. 5 b and 5c show respectively the detail drawing that forms PMOS drain extension 148 and pmos source and drain region 155.If put upside down doping type, Fig. 5 a is identical with structure &processes shown in 5b.In Fig. 5 b, by implanting a boron bunch implant 147, form PMOS drain extension 148.For 0.13 μ m technology node, the canonical parameter of this time implanting is that 500eV/ boron atom and dosage are 5 * 10 ¹⁴cm ^-2.Therefore, B ₁₀h _xthe energy of implanting is that 5keV and decaborane dosage are 5 * 10 ¹³cm ^-2.Fig. 5 c shows again by implanting one such as the P-type ion beam such as decaborane 154 formation pmos source and drain regions 148.For 0.13 μ m technology node, the dosage that the canonical parameter of this time implanting is 2keV/ boron atom and boron is 5 * 10 ¹⁵cm ^-2(5 * 10 ¹⁴cm ^-2the 20keV decaborane).

Generally speaking, implanted ions self is not enough to form an efficient semiconductor knot; For implanted dopant is electrically activated, need to heat-treat.After implanting, the crystal structure of Semiconductor substrate can be subject to heavy damage (substrate atoms is moved out of lattice position), and the dopant of implanting only weak binding is to substrate atoms, thereby the electrical property of institute's implant layer is poor.Normally at high temperature (higher than 900 ℃) are implemented heat treatment or are annealed the repairing semiconductor crystal structure, and dopant atom is located in the replacement mode, are about to dopant atom and are placed in one of them substrate atoms position of crystal structure.It is electroactive that this kind of replacement makes dopant combine and to become with substrate atoms to have; In other words, change the conductance of semiconductor layer.Yet this kind of heat treatment meeting has the opposite effect to the formation of shallow junction, this is because during heating treatment the dopant of implanting can spread.In fact, the diffusion of the boron of during Heat Treatment is to obtain the limiting factor of USJ in inferior 0.1 micrometer range.For the diffusion that makes shallow implantation dopant minimizes, developed at present for this kind of heat treated advanced technologies, for example " peak value annealing ".Peak value annealing is a kind of quick thermal treatment process: wherein at the residence time at maximum temperature place close to zero: temperature suddenly rises as quickly as possible and descends.By this kind of method, reach activate the required high temperature of the dopant of implanting make the diffusion of implanted dopant minimize simultaneously.Can expect, this kind of advanced person's Technology for Heating Processing will be combined with the present invention, so that it maximizes the benefit of making completed semiconductor devices.

Fig. 6 demonstrates the generation of phosphorus cluster ion and passes through the formation of the phosphorus ion beam of quality discrimination.This mass spectrum shows use hydrogen phosphide (PH ₃) as source material gas, at ion source duration of work of the present invention, fetch data.This mass spectrum shows that (it determines mass of ion: relation charge ratio) for ionic current intensity on vertical scale 61 and the analyzer magnetic field on horizontal scale 62.Electric current is measured in a Faraday cup that wherein secondary electron is subject to effectively restraining.Horizontal scale 62 is linear with magnetic field, but with quality: charge ratio becomes non-linear relation, because, for a set extraction voltage V, the pass between these two amounts is m/q=aB ², wherein a is a constant.This make higher quality peak value on horizontal scale 62 the closer in together.Phosphorus bunch is to observe as signal 65,66 and 67, and it has respectively two, three and four phosphorus atoms/every bunch.To this mass spectral:mass spectrographic the analysis showed that, formation and maintenance that ion source of the present invention can be supported bunch during operation.In figure, first group of signal 63 in left side is hydrogen ion, and its mass number is 1 and 2.The peak value less of hydrogen, much smaller than the peak value containing phosphonium ion.Second group of signal 64 comes across between quality 31 and 35, and it is corresponding to the ion that contains a phosphorus atoms.In a traditional implantation technique, the selection in visual selected quality discrimination hole 27 (referring to Fig. 2) and determining, implant one, several or all these peak values.In some applications, if comparatively responsive to H in technique, may require only to select ³¹p ⁺peak value.In such cases, can adopt a narrow quality discrimination hole to get rid of hydride peak value, for example PH _x ⁺, x=1 wherein, 2,3 or 4.Other techniques may require to implant all peak values in this group, to boost productivity.Next group signal 65 on right side is by the dimer P of phosphorus ₂ ^-form, wherein each particle in these particles all contains two phosphorus atoms.The P that the large-signal of the leftmost side is 62 corresponding to mass number ₂ ⁺, the adjacent signals on right side is corresponding to P ₂h _x ⁺signal, wherein x is between 1 and 6.Also notice, the intensity of these signals reduces than monomer peak value 64, but the intensity observed depends on whole group of source input set point, also can be optimized for required ion beam conditions, if for example dimer is used in expectation, makes P ₂ ⁺the relative weight of peak value maximizes.The choosing of quality discrimination hole can define how many these ion beams will be implanted in implanting technique.Next signal group 66 on right side is corresponding to containing three phosphorus atoms (P ₃ ⁺) the phosphorus cluster ion.Next signal 67 on right side is corresponding to the phosphorus cluster ion that contains four phosphorus atoms.What is interesting is, we can notice, the intensity of this bunch is greater than P ₃h _x ⁺bunch, use P ₄ ⁺bunch the time clean dose rate (4 * institute observed strength) higher than implanting P ⁺or P ₂ ⁺the time clean dose rate, and the energy of each phosphorus atoms of implanting only for the nominal ion beam energy 1/4.

Fig. 7 shows AsH when use is of the present invention ₃mass spectrum.Ion beam energy is 19keV, thereby As ₄h _x ⁺effective As to implant energy will be 4.75keV.As in Fig. 7 ₄h _x ⁺ion beam current be about 0.25mA, thereby the equivalence As dopant electric current be about 1mA.Fig. 7 also shows, implants and contains As, As ₂, As ₃or As ₄ion beam will obtain the ionic current between 0.5mA and 1.0mA, and only by regulating the analyzer magnet current, select mass spectral:mass spectrographic different piece shown in Fig. 7, also can obtain between approximately 20 and 5keV between effective implantation energy range.

Fig. 8 shows As ₄h _x ⁺electric current and As implant the functional relation of energy.The angular divergence of ion beam laterally or disperse on direction and be limited to half angle or 11mR, or is about 0.6 degree by the hole between quality discrimination hole (for example, referring to 27 in Fig. 3) and Faraday cup.The 1keV/ atom is arsenic to be implanted to the lower limit of semiconductor technology required in the USJ device.

Fig. 9 demonstration is scaled the ion beam brill by ion beam current shown in Fig. 8, and compares with one " typical case's " modern medium electric current implanter.Its improvement amount is about 30 times (technical specification of supposing this medium current implanter is: 40mrad half angle acceptance, the ion beam current under 10keV is 200 μ A).Stephens is defined as brightness B in ion embedding technology handbook (Handbook of Ion Implantation Technology, J.F.Ziegler version, North-Holland, 455-499 page (1992)):

(6)B＝2I/π ²ε ²(μA-mm ²-mrad ²)，

Wherein I is Effective Doping agent ion beam current (unit is microampere), and ε is the ion beam emittance, and unit is square (a milliradian-millimeter).Emittance is calculated by following formula:

(7)ε＝δa，

Wherein δ is the half width of ion beam in dispersive plane, and a is half cone pencil of forms angle, and the two differentiating that the place, hole site records all at plane of delineation place.

Ion beam brightness is one for quantizing, have how many ion beam currents (for example) to convert the important indicator of certain receiving amount to by a pipe with certain diameter and length.Because the Ion Implantation Equipment bunch has the receiving amount of clear, thereby for emittance for limited ion beam, brightness is that an important productivity ratio is measured.Emittance is the limiting factor of low energy beam in transporting normally.We notice, this is to use cluster ion but not the benefit place of using the monomer ion basically, as shown in equation (1)-(3).For As ₄implant, according to equation (3), estimate that the raising amount for the treatment of capacity is 16 times, i.e. Δ=n ².

Figure 10 demonstration is used AsH respectively under 4.75keV and 19keV _x ⁺and As ₄h _x ⁺the secondary ion mass spectroscopy (SIMS) that ion pair silicon sample obtains while being implanted.Atom dosage is about 1 * 10 ¹⁶cm ^-2.By these data with one in the sector simulation while in silicon, carrying out implanted ions usually complete dynamic scattering model TRIM used compare, result shows, we just implant As and As with prescribed energy really ₄.

Figure 11 shows diborane B ₂h ₆mass spectrum, diborane is a kind of in conventional ion is implanted and be of little use but market gaseous material on sale.Figure 11 shows H (H ⁺, H ₂ ⁺, H ₃ ⁺), B (B, BH ⁺, BH ₂ ⁺), B ₂(B ₂ ⁺, B ₂h ⁺, B ₂h ₂ ⁺, B ₂h ₃ ⁺, B ₂h ₄ ⁺), B ₃(B ₃, B ₃h ⁺, B ₃h ₂ ⁺, B ₃h ₃ ⁺, B ₃h ₄ ⁺), B ₄(B ₄, B ₄h ⁺, B ₄h ₂ ⁺, B ₄h ₃ ⁺, B ₄h ₄ ⁺) grouping and a B5 group.Mass spectral:mass spectrographic deciphering shown in Figure 11 may be slightly complicated, and this is because there is the isotope of the boron of two kinds of Lock-ins ¹⁰b reaches ¹¹b, it was with approximately 4: 1 ¹¹b couple ¹⁰the B ratio means, this ratio has reflected its natural abundance.For example, at the peak value place with 11 atomic mass units, exist simultaneously ¹¹b reaches ¹⁰bH the two.

Figure 12 demonstrates the generation of hydride bunch and the positive cluster ion of boron in the present invention.This mass spectrum is presented at the decaborane B that uses gasification ₁₀h ₁₄during as the source raw material, at ion source duration of work of the present invention, fetch data.Show B in figure _yh _x ⁺the hydride bunch of the boron of form (wherein 1≤y≤10,0≤x≤14), its be separated by respectively 1amu and from 1amu to about 124amu.The peak signal B observed ₁₀h _x ⁺corresponding to the decaborane molecule ion, it is by decaborane parent molecule direct ion is formed.

Figure 13 shows a decaborane negative ion mass spectrum produced by ion source of the present invention, and it is similar to mass spectrum shown in Figure 12.The negative formed ionic condition of decaborane ion is wanted much less, thereby the ion packet of most of (approximately 90%) is contained in female B ₁₀h _x ^-in peak value.It uses anion to carry out implanted ions to semiconductor very useful, because can essence eliminate the disk charging phenomenon observed when cation is implanted.Usually, an ion source can not produce simultaneously enough cations of a set material and anion the two; Peak value ionic current shown in Figure 12 and 13 identical (in twice).In Figure 14, for the mass range of an expansion, this has been carried out to distinct demonstration.These data are collected in the following way: use implanted ions systematic collection one positive ion mass spectrum of the present invention, and the polarity of the implanted ions electromechanical source that then reverses, and collect the negative ion mass spectrum in the equal in quality scope on same a piece of paper.For collecting Figure 14, by Faraday cup current feed to x-y paper records instrument.Implant anion but not implant cation in use decaborane situation and can obviously have some important advantage: 1) more useful ionic current is arranged in interested peak value, thereby produce larger useful dopant flux; 2) quality of parent peak value has narrowed down nearly 1/2nd (the full width at second maximum place of anion situation has been 5 atomic mass units, and in the cation situation, be nine atomic mass units), and 3) when using anion to replace cation, eliminated the disk charging phenomenon, this is widely accepted in affiliated technical field.

Figure 15 shows with the two SIMS distribution curve of the positive decaborane ion in the decaborane energy implanted silicon sample of 20keV and negative decaborane ion.If each ion all has the boron atom of equal number, these distribution curves can be intimate identical as people estimate, and therefore implant identical preset range.

Figure 16 shows the SIMS data in negative decaborane implantation situation, and it has also shown the concentration of H.0.9 times of the dosage that the dosage of H is boron, this average chemical molecular formula that shows negative decaborane is B ₁₀h ₉ ^-.

Figure 17 is presented at ionization probability in electronic impact ionization situation and how depends on electron energy.Use ammonia (NH in figure ₃) as example, separate.In figure, probability is expressed as to cross section sigma, unit is 10 ^-16cm ².The unit of electron energy (T) is eV, i.e. electronics-volt.Show the test data that two groups of theoretical curves that calculate according to First Principle (being labeled as BEB (vertically IP) and BEB (adiabatic IP)) and two groups are drawn by the people such as Djuric (1981) and Rao and Srivastava (1992) in figure.Figure 17 has shown the following fact: some electron energy scope can cause ionization greatly than other energy ranges.Although these data are applicable to produce cation, yet similar Consideration also is applicable to the generation of anion: obviously have strong energy dependence.Generally speaking, produce the cross section maximum of cation when the electronic impact energy is between about 50eV and 500eV, and reaches peak value when about 100eV.Therefore, energy when electron beam enters chamber 44 is an important parameter, and it can affect the ionogenic operation of the present invention, so the energy that our designed electron beam transports the electronics that makes to infiltrate chamber is approaching zero eV to variable between about 5000eV.Fig. 2 b to Fig. 2 d shown device shown the present invention how to comprise can to electronic impact ionization energy carry out broad control simultaneously ionogenic electron beam form and deflecting region in approaching the electron-optical arrangement of working under constant condition.

Figure 18 is the mass spectrum of the positive decaborane ion of use ion source generation of the present invention.Marked respectively in figure and formed these mass spectral:mass spectrographic various ions.Generally speaking, these ions are B _nh _x ⁺form, wherein 1≤n≤10,0≤x≤14.Maximum peak value is female B ₁₀h _x ⁺ion, wherein the major part of this peak strength is in about 8amu (atomic mass unit).This parent ion may be selected to implant for cation.

Figure 19 is the negative decaborane ion of use ion source generation of the present invention and the mass spectrum of positive decaborane ion.Marked respectively in figure and formed these mass spectral:mass spectrographic various ions.Wherein the anion spectrum is simple more than the cation spectrum.Particularly, do not have obvious hydrogen ion or low order boron ion more, and this mass spectral:mass spectrographic 90% be approximately by female B ₁₀h _x ⁺ion forms.With B ₁₀h _m ⁺seemingly, most of peak strength of this negative parent ion is in about 8amu for Ion Phase.This parent ion may be selected to implant for anion.

There is several element to be used in semiconductor and form shallow junction.For the silicon application, main dopant is boron, phosphorus, arsenic and antimony, thereby these elements most possibly are used to form shallow junction.In addition, silicon and germanium implant be for forming amorphous areas at silicon, thus these factors bunch will be applicable to form shallow amorphous areas.For compound semiconductor, the element that is applicable to shallow junction comprises silicon, germanium, tin, zinc, cadmium and beryllium, thereby bunch the having an opportunity in the compound semiconductor manufacture, forming shallow junction of these elements.

An aspect of the method is that the correct environment that is applicable to form cluster ion is provided in chamber.Each element in described various element all has different chemical property, thereby suitable environment can be different because of each element.For obtaining optimum performance, each element and each selected bunch all will require to use one group of different input parameters.Being available for carrying out optimized parameter comprises: by the source pressure of raw material current control, temperature in the chamber of being controlled by temperature control system, ionization energy intensity and characteristic, for example electron beam current when the ionization energy is electron beam and electron energy.These basic parameters form together and are applicable to form dopant bunch and by the suitable source ion room environmental of dopant cluster ion.

As described above, with the implanted ions of single dopant atom, compare, the implanted ions of dopant atom bunch make people can be efficiently with a shallow degree of depth implant N-type and P-type dopant the two.

Above together with some embodiment, set forth the present invention.Yet the present invention is not limited to this.For example, the person of ordinary skill in the field easily knows, also can make various modifications, change, improvement and combination to it.

Obviously, according to institute's teaching content above, can make many modifications and changes to the present invention.Therefore, should be appreciated that, can be in claims scope of enclosing, be different from above concrete other modes of setting forth implement the present invention.

Claims (16)

1. one kind dopant material is implanted to the method in a substrate, the method comprises the steps:

Produce As _nh _x ⁺the N-type cluster ion of form, wherein n and x are integer, and n=2,3 or the scope of 4, x in 0≤x≤n+2 in;

Produce P-type cluster ion from one second molecular substance;

Described N-type cluster ion is implanted in the first area on a substrate; And

Described P-type cluster ion is implanted in the second area on described substrate.

2. the method for claim 1, wherein produce As from one first molecular substance _nh _x ⁺the step of the N-type cluster ion of form comprises: from arsenic hydride (AsH ₃) the described N-type of γ-ray emission cluster ion.

3. the method for claim 1, wherein produce As from one first molecular substance _nh _x ⁺the step of the N-type cluster ion of form comprises: from the steam As of element arsenic, produce described N-type cluster ion.

4. method as claimed in claim 2, wherein produce As from one first molecular substance _nh _x ⁺the step of the N-type cluster ion of form comprises: produce As ₄ ⁺cluster ion.

5. method as claimed in claim 3, wherein produce As from one first molecular substance _nh _x ⁺the step of the N-type cluster ion of form comprises: produce As ₄ ⁺cluster ion.

6. method as claimed in claim 2, wherein produce As from one first molecular substance _nh _x ⁺the step of the N-type cluster ion of form comprises: produce As ₃ ⁺cluster ion.

7. method as claimed in claim 3, wherein produce As from one first molecular substance _nh _x ⁺the step of the N-type cluster ion of form comprises: produce As ₃ ⁺cluster ion.

8. method as claimed in claim 2, wherein produce As from one first molecular substance _nh _x ⁺the step of the N-type cluster ion of form comprises: produce As ₂ ⁺cluster ion.

9. method as claimed in claim 3, wherein produce As from one first molecular substance _nh _x ⁺the step of the N-type cluster ion of form comprises: produce As ₂ ⁺cluster ion.

10. method as claimed in claim 2, wherein produce As from one first molecular substance _nh _x ⁺the step of the N-type cluster ion of form comprises: produce As ₄h _x ⁺cluster ion, wherein x is an integer and 1≤x≤6.

11. method as claimed in claim 2, wherein produce As from one first molecular substance _nh _x ⁺the step of the N-type cluster ion of form comprises: produce As ₃h _x ⁺cluster ion, wherein x is an integer and 1≤x≤5.

12. method as claimed in claim 2, wherein produce As from one first molecular substance _nh _x ⁺the step of the N-type cluster ion of form comprises: produce As ₂h _x ⁺cluster ion, wherein x is an integer and 1≤x≤4.

13. the method for claim 1, wherein the step from one second molecular substance generation P-type cluster ion comprises: from decaborane (B ₁₀h ₁₄) the described cluster ion of γ-ray emission.

14. method as claimed in claim 13, wherein the step from one second molecular substance generation P-type cluster ion comprises: produce B _nh _x ⁺cluster ion, wherein n and x are integer and 2≤n≤10,0≤x≤14.

15. method as claimed in claim 14, wherein the step from one second molecular substance generation P-type cluster ion comprises: produce B ₁₀h _x ⁺cluster ion, wherein x is an integer and 0≤x≤14.

16. the method for claim 1, wherein the step from one second molecular substance generation P-type cluster ion comprises: produce negative B ₁₀h _x ^-cluster ion, wherein x is an integer and 0≤x≤14.

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