Source: https://patents.google.com/patent/CN106663699A/en
Timestamp: 2020-07-13 16:08:34
Document Index: 218688119

Matched Legal Cases: ['arts 824', 'art 954', 'art 1058', 'arts 1024', 'arts 1124', 'arts 1358']

CN106663699A - Methods and apparatus for LDMOS devices with cascaded RESURF implants and double buffers - Google Patents
CN106663699A
CN106663699A CN201580042187.4A CN201580042187A CN106663699A CN 106663699 A CN106663699 A CN 106663699A CN 201580042187 A CN201580042187 A CN 201580042187A CN 106663699 A CN106663699 A CN 106663699A
CN201580042187.4A
CN106663699B (en
2015-08-07 Application filed by 德州仪器公司 filed Critical 德州仪器公司
2015-08-07 Priority to PCT/US2015/044317 priority patent/WO2016022975A1/en
2017-05-10 Publication of CN106663699A publication Critical patent/CN106663699A/en
2020-06-05 Publication of CN106663699B publication Critical patent/CN106663699B/en
238000002955 isolation Methods 0.000 claims abstract description 47
238000002513 implantation Methods 0.000 claims description 62
150000002500 ions Chemical class 0.000 claims description 30
230000003139 buffering Effects 0.000 claims description 19
239000002019 doping agents Substances 0.000 description 16
229910052785 arsenic Inorganic materials 0.000 description 5
For cascading the side of the LDMOS devices of RESURF implanting portions and double buffering with Jing Method and equipment
This is related to the field of integrated circuit (IC), and more particularly to lateral double diffusion metal oxide semiconductor (LDMOS) making of device.
The needs that pair can provide the transistor of the high power driving force on semiconductor integrated circuit cause horizontal double diffusion The development of metal-oxide semiconductor (MOS) (LDMOS) device.Especially significant application is comprising for defeated for LDMOS devices Go out the high-side driver and low side driver of buffer and radio frequency (RF) circuit.Bilateral diffusion MOS device (DMOS) is used to wherein need Want high-voltage capability and low-resistance application.Ldmos transistor shows high-breakdown-voltage BVdss and low on-resistance RDSon, And therefore it is very suitable for high power applications.
In the transistor formed with DMOS techniques, source electrode and backgate diffusion are by the synchronization in substrate or while holding It is capable be ion implanted and subsequent drive annealing and formed.Drain diffusion portion is spaced apart drift with the channel region of underlying gate electrode Region, the drift region area of isolation that can underlie is formed.The interval between gained diffusion part at the surface of Semiconductor substrate Determine the channel length of ldmos transistor.
Fig. 1 describes in cross conventional LDMOS devices 100.In FIG, there is provided p-type semiconductor substrate 110.In figure Show the p-type epitaxial layer 114 being formed above the substrate in 1.N-type embedded layer (be labeled as " NBL " and numbering is 120) exhibition It is shown at the bottom of LDMOS structure.NBL 120 is formed by optical mask pattern and ion implanted step.Equally, p-type is shown Embedded region (is labeled as " PBL " and numbering is 116).These regions are by the second independent mask patterning and independent ion Implantation step is formed.LDMOS devices 100 are included and are formed on the either side of the source region in diffusion part DWL 136 Two symmetric parts, have grid and drain electrode arrangement per side.Generally, these region couples are together to form big transistor, But alternatively form two transistors with common source and backgate part.The similar many regions for being formed and being arranged can be total to It is same to couple to form larger transistor.
In FIG, the deep N-well region that numbering is 118 is shown on the either side in EPI regions 114.In region 118 In each, displaying forms the shallow N traps (be labeled as " SNW " and numbering is 121) of drain diffusion.Outside deep N-well region 118, Show shallow p-well (be labeled as " SPW " and numbering is 122).While P-EPI 114 and PBL 116 are processed, this also forms integrated Isolating between formula LDMOS device 100 and other neighbouring device knots.In each of region 118, P embedded layers region (numbering is 116) on the top of NBL 120, as shown in FIG, so as to form PBL regions between DNW regions Charge balance and realize the reduction surface field effect (" RESURF ") of LDMOS devices.In exemplary placement, deep N-well 118 can be by N-shaped doped region is formed, and shallow N well region (it is 121 to be labeled as " SNW ", numbering) can be by the semiconductor technology of mos device Low voltage cmos N-type diffusion trap formed.These SNW regions 112 are used to form LDMOS drain contacts being electrically connected to DNW 118 Connect.Additionally, the drain terminal D being formed in the conductor overlie on substrate can be coupled and by CMOS sources with drain contact region 128 Pole/drain electrode n+ doping diffusion parts are formed.
In FIG, show two gate electrodes overlie on substrate surface (numbering is 132).In operation, gate terminal Current potential on son will make transistor turns and form wherein carrier in the substrate that the channel region of drain electrode can be advanced to from source electrode. N+ source regions (numbering is 134) are formed in p-type D trap diffusion part (be labeled as DWL and numbering is 136).It is adjacent with N+ source electrodes 134 The extra P+D traps contact area 135 for connecing is for the connection of D traps.Isolation oxidation object area 130 (it can isolate to be formed by shallow trench) It is shown as in FIG overlying on drift region and being labeled as " STI ".DNW is by being ion implanted offer to be formed under STI The drift region (being labeled as " RESURF " 138) of side, the drift region provides the reduction surface field effect for ldmos transistor Answer (" RESURF ").RESURF ldmos transistors have increased breakdown voltage BVdss for disposing by power device Jing The high voltage received.
In operation, electronic carrier is crossed from source region transition and is formed at grid channel below region and then transition Cross drift region and reach drain terminal.In instances, source terminal S is coupled to earthing potential, and high voltage (such as 35 volts, 50 volts or higher volt) it is coupled to drain terminal.Current potential at gate terminal 132 can be then used in turns on device, and high Power current then flows through described device (from drain-to-source, in opposite direction with electronic carrier).
In the known method with regard to power device, using for ldmos transistor is provided with high-breakdown-voltage characteristic (its Very high voltage (such as 50 volts at source electrode or drain terminal) can be disposed) and with the device of rather low resistance Rdson. However, existing LDMOS devices 100 depicted in figure 1 suffer from various problems and performance issue.Also need to require less silicon face Long-pending device with increase it is integrated and reduce comprising ldmos transistor integrated circuit area.In the high electricity of the target of LDMOS devices At pressure, the single RESURF in drift region can be not enough to dispose the reduced drift occurred in semiconductor technology continual reductions High voltage under length between device drain-to-source.Additionally, under less drift length, region " X " (JFET areas, in FIG Be labeled as " X ") in electric field become relatively strong, this easily induces relatively low device drain-to-source breakdown voltage and also causes electric current Pour in and mark in " X " region, and this can cause channel hot carrier (" CHC ") effect.For example, in CHC, some loads Stream (electronics or hole) can be tunneling in gate-dielectric and be trapped, so that gate dielectric material degrades and reduces brilliant Body pipe device performance and reliability.Equally, the use of embedded layer " NBL " and " PBL " by need extra and particular photomask, Pattern and implantation step and add complexity to standard CMOS semiconductor manufacturing process, so as to increase production cost.
In described example, a kind of LDMOS devices are included：At least one drift region, it is placed in Semiconductor substrate A part in；At least one isolation structure, it is located at the surface of the Semiconductor substrate；D well areas, it is neighbouring described extremely Lack a part for a drift region and position, and the drift region is conductive with the formation first of the joining of the D well areas Knot of the property between type and the second conductivity-type；Grid structure, it is placed in the semiconductor substrate；Source contact area Domain, it is placed on the surface of the D well areas；Drain contact region, it is disposed adjacent to the isolation structure；And double buffering Device region, it is included：First embedded layer, it is located at below the D well areas and the drift region and is doped to described Second conductivity-type；And the second high voltage deep diffusion layer, it is located at below the first embedded layer and is doped to described First conductivity-type.
Fig. 1 describes the exemplary LDMOS device of existing method in simplified cross-sectional view.
Fig. 2 to 12 illustrates to the semiconductor technology arrangement using subject application to make in a series of cross-sectional views Make the continuous processing step of LDMOS devices.
Figure 13 is illustrated in cross the ldmos transistor and PMOS transistor of construction located adjacent one another on substrate Arrangement.
Figure 14 describes in flow charts to form the first of LDMOS devices in the semiconductor technology of subject application arrangement Number of processing steps.
Figure 15 describes the additional process steps for forming LDMOS devices in semiconductor processing in another flow chart.
Each figure is not necessarily drawn to scale.
There are the lasting needs to the ldmos transistor device with improved reduction surface field effect performance.Need There is can manufacturing together with standard CMOS device for reduced process steps and reduced cost when compared with the conventional method Ldmos transistor.Exist to very high-breakdown-voltage BVdss, reduced conducting resistance, improved CHC performances and with more Low cost needs the needs of the LDMOS devices of the silicon area less than the silicon area required for existing LDMOS devices.
The arrangement for forming the various aspects of subject application provides the LDMOS devices being formed in semiconductor technology, described There is LDMOS devices double buffering to arrange and further using chained ion implantation step be formed to drift region and D traps Cascade resurf diffusion parts are included in both regions to realize high-performance.Also disclose corresponding method arrangement.
In exemplary placement, a kind of LDMOS devices are included：At least one drift region, it is placed in Semiconductor substrate A part in and be doped to the first conductivity-type；At least one isolation structure, it is located at the table of the Semiconductor substrate At face and be positioned at least one drift region a part in；D well areas, it is located at the another of the Semiconductor substrate In part, it is doped to a part for the second conductivity-type and neighbouring at least one drift region and positions, and it is described The joining of drift region and the D well areas is formed between first conductivity-type and second conductivity-type Knot；Grid structure, it is placed on the surface of the Semiconductor substrate and overlies the one of channel region and the isolation structure On part, the grid structure is comprising the gate dielectric layer above the channel region and overlies grid electricity Jie Gate conductor materials in matter；Source contact regions, it is placed on the surface of the D well areas and in the neighbouring channel region At the side in domain, the source contact regions start to be doped to first conductivity-type；Drain contact region, its placement In shallow diffusion trap on the surface of the drift region and the neighbouring isolation structure and by the isolation structure with it is described Channel region is spaced apart, and the drain contact and the shallow diffusion trap are doped to first conductivity-type；And double buffering Device region, it is included：First embedded layer, it is located at below the D well areas and the drift region and is doped to described Second conductivity-type；And the second high voltage deep diffusion layer, it is located at below the first embedded layer and is doped to described First conductivity-type.
In another arrangement, a kind of method for forming LDMOS devices is included：Semiconductor substrate is provided；Described half Conductor substrate top forms epitaxial layer；The is formed by implant impurity in the epitaxial layer square on the semiconductor substrate First embedded layer of one conductivity-type, the epitaxial layer and the Semiconductor substrate are doped to the second conductivity-type； The in-line arrangement epitaxial layer of second conductivity-type is formed above the embedded layer；Perform the institute in the implantation of the first chain type State the first of the first conductivity-type to be ion implanted to form high voltage deep trap buffer areas；Perform the second electric conductivity class Being ion implanted for type is placed in the second embedded layer between high voltage well area and drift region to be formed, high voltage deep-well region Domain and the second embedded layer form double buffering region；Formed at the surface of the Semiconductor substrate and be located at described first Area of isolation in the trap of conductivity-type；Over the substrate side deposits gate-dielectric, in the gate-dielectric Disposed thereon grid conductor, and then etch the grid conductor and the gate-dielectric is overlie on channel region to be formed Grid structure；And implant impurity is forming the source region and shape that are spaced apart with the grid structure by the channel region Into the drain region being spaced apart with the grid structure in the drift region and by the area of isolation.
In another arrangement, a kind of integrated circuit is included：LDMOS devices, it is further included：At least one drift region Domain, it is placed in a part for Semiconductor substrate and is doped to the first conductivity-type；At least one isolation structure, its position At the surface of the Semiconductor substrate and be positioned at least one drift region a part in；D well areas, it is located at In another part of the Semiconductor substrate, the second conductivity-type is doped to and adjacent at least one drift region A part and position, and the drift region and the joining of the D well areas formed first conductivity-type with it is described Knot between second conductivity-type；Grid structure, it is placed on the surface of the Semiconductor substrate and overlies channel region In a part for domain and the isolation structure, the grid structure includes the gate dielectric layer above the channel region And overlie gate conductor materials on the gate-dielectric；Source contact regions, it is placed in the surface of the D well areas Above and at the side of the neighbouring channel region, the source contact regions start to be doped to the first electric conductivity class Type；Drain contact region, its be placed in the shallow diffusion trap on the surface of the drift region and the neighbouring isolation structure and It is spaced apart with the channel region by the isolation structure, the drain contact and the shallow diffusion trap are doped to described the One conductivity-type；And double buffering region, it is included：First embedded layer, it is located at the D well areas and the drift region Below domain and it is doped to second conductivity-type；And the second high voltage deep diffusion layer, it is located at first embedded Layer below and is doped to first conductivity-type；And at least one CMOS device, it is formed at the Semiconductor substrate In and be spaced apart with the LDMOS devices.
Recognize in subject application, high voltage is overlie by p-type embedded layer with being formed above N-shaped embedded layer The arrangement of the ldmos transistor of the double buffering formed on deep N-well layer provides high-performance ldmos transistor.Additionally arranging In, chain type resurf diffusion implanting portion is formed in both the drift region and body region with further reduce surface field effect, Solve the problems, such as channel hot carrier and reduce mask level to reduce cost.Using comprising power transistor device (such as downside And high-side driver), automobile application, RF circuits and high-frequency device.
Subject application includes some arrangements, and the arrangement is described in various implantation used in CMOS compatibility semiconductor technologies and comes Form Jing diffusion zones to form LDMOS devices.For MOS transistor device, title " source electrode " and " drain electrode " refer to these areas The electrical connection in domain, and in the cross-sectional view of the physical arrangement of mos device, " source electrode " and " drain electrode " is usually and is formed at transistor Identical and symmetrical doped diffusion zone on the opposite side of grid.In many cases can be by inverting " source electrode " and " drain electrode " Region and form extra alternative arrangement.
Because the various ion implanted steps used when the LDMOS RESURF devices with arrangement are formed are similar to Ion implanted step used in MOS manufacture crafts, therefore with relatively low cost realization to produce LDMOS RESURF dresses The technique put.Equally, the technique can be used to produce and the NMOS in LDMOS RESURF device identical integrated circuits simultaneously And/or PMOS transistor.In this way, the CMOS device produced together with LDMOS devices can be used to form control circuit, calculate Circuit and input/output circuitry, so as to form the single integrated circuit with all required circuits with by LDMOS devices be used for can In existing semiconductor technology in the system of easy to manufacture.It is being also contemplated within to form the alternative of the additional aspect of subject application In, it is integrated that LDMOS RESURF transistor units can be formed at arranged type in the case where extra NMOS and PMOS device is not needed On circuit arrangement.
Fig. 2 describes and is illustrated in a series of of the consecutive steps that perform during construction LDMOS Jing cascade RESURF devices 200 One in cross section.LDMOS Jing cascade RESURF devices 200 can be in some arrangements with to existing cmos semiconductor technique Somewhat modification and formed.Those skilled in the relevant art will be recognized that exist and realize according to this LDMOS Jing cascade RESURF devices Construction alternative and order of steps, and this non-limiting example of making is only in those methods of this configuration Person.Trustship LDMOS Jing cascade RESURF devices (and in some arrangements for some aspects for forming subject application, also trustship its Its MOS transistor device) Semiconductor substrate 210 can be p type single crystal silicon substrate in an exemplary placement.In CMOS technology (it is including but not limited to silicon-on-insulator (SOI) or mixing directional technology (HOT) for any substrate of middle support making integrated circuit Substrate) in or on any epitaxial layer compatible with cmos semiconductor making form LDMOS Jing cascade RESURF devices also at this In the range of application case.In fig. 2, initial epitaxial layer 212 is shown, P-type layer is overlie in the initial epitaxial layer.Can be at some This epitaxial layer is omitted in alternative arrangement.Substrate 210 and epitaxial layer 212 are provided for semiconductor work in an exemplary placement The parent material of skill.In other arrangements, epitaxial layer 212 is omitted.
Fig. 3 is depicted in cross under the making for illustrating N-type embedded layer or " NBL " (numbering is 314) LDMOS Jing cascade RESURF devices 300 after one step.To form such as this layer for being shown in figure 3, on substrate 310 The blanket of Fang Zhihang n-type dopant species covers implantation 351 to form NBL 314.In step after a while described below, can be formed Deep trench or the deep trench with n+ materials and the deep trench can be coupled to NBL to form N-type groove.This groove can be used for by Other areas and other devices on LDMOS Jing cascades RESURF devices 300 and substrate 310 are electrically insulated.As opened up in figure 3 Show, embedded layer 314 is formed as covering implantation to the blanket of the P-epi 312 of the top of substrate 310.This forms distinctness with existing method Contrast, and blanket covers implantation and does not need mask, photoresist, patterning and photoresist divesting technology, alternatively can be not Being ion implanted for NBL 314 is performed in the case of needing photomask.Can be non-by the way that n-type dopant (such as phosphorus or arsenic) is implanted to Often high concentration and form NBL 314.For example, 5 × l0 can be used15Atom/cm2Implant dosage.In alternative arrangement, can NBL 314 was formed using mask layer before implantation step is performed.In here arrangement, N-shaped can be formed around LDMOS devices Slot structure.
Fig. 4 is depicted in cross the following step performed during construction LDMOS devices 400.In the diagram, hold Row in-line arrangement epitaxy technique is with the formation p-type epitaxial layer 416 above N-shaped embedded layer NBL 414.Also show that initiation layer p extensions Layer 412 and substrate 410, it is arranged as described above.
Fig. 5 is depicted in cross the LDMOS devices 500 after extra continuous making step.In Figure 5, use Mask and Patternized technique are performing a succession of ion implanted step of n-type dopant to form Resist patterns 537.Outside p Several ion implantation regions are formed in the part for prolonging layer 516.For example, in the first ion implanted step, by 2MeV To under the energy of 3MeV and 1 × 1012Atom/cm2To 3 × 1012Atom/cm2Implant dosage under carry out being ion implanted for phosphorus And form high voltage deep N-well buffer 518.
It is ion implanted after 531 in deep N-well buffer, the implantation energy and～2 × l0 of (such as) in 600KeV to 2MeV12 Atom/cm2To～5 × l012Atom/cm2Implant dosage under use phosphorus perform as dopant atom chain type implantation in Second N-shaped is ion implanted (numbering is 533).This forms N-shaped doped region in drift region 522.
Again referring to Fig. 5, perform the 3rd implantation in N-shaped ion implanted step chain with " JFET " region (numbering is 524) Middle formation implanting portion.Execution is ion implanted 535 to form JFET regions, and in an arrangement, this implantation can be arrived in l00Kev Under the implantation energy of 350KeV and in～1 × l012Atom/cm2To 9 × l012Atom/cm2Implant dosage under use arsenic doping Agent atom.In this way, continuously perform N-shaped chain to be ion implanted and step or process need not be intervened.By in these implantation steps The mask 537 that period uses forms N-shaped trap so that form p-n junction along line 526.After performing N-shaped and chain is ion implanted, hold Row is referred to as the hot step of actuation step so that diffusion zone is complete.
Fig. 6 illustrates the extra continuous process step to form LDMOS devices 600 in another cross-sectional view.In Fig. 6 In, displaying numbering is that 651 ion implanted step and the ion implanted step are performed to form p-type embedded layer PBL 628.In an arrangement, this implantation step is to cover implantation using blanket to perform so that does not need mask, patterning and etches step And the dopant that used can be boron suddenly,.Can be from～3 × 1012Atom/cm2To 8 × 1012Atom/cm2Implant dosage under Using the implantation energy of 800KeV to 2.5MeV.It is included in HV deep N-well buffers (numbering is 618) demonstrated in Figure 6 and p is hidden The arrangement of buried layer PBL (numbering is 628) forms the double buffering feature for LDMOS devices.LDMOS devices drift region electricity Resistance can balance RESURF designs and significantly subtract by the special PBL buffers 628 of subject application to N traps 622 area charges of drift It is little.In the arrangement of subject application, realize turning on shape for device due to the higher HV deep N-wells doping content at deep junction depth The very low drifting zone resistance of state.(it will be placed in area of isolation of the following article described in step after a while to drift region 622 STI lower sections) can be kept apart by the depleted region of the p-n junction the drift region 622 of PBL buffers 628 to HV deep N-wells 618, So as to realize higher drain-to-source off state breakdown voltage.Relatively high PBL buffers doping content is needed so that highly doped N The charge balance of trap drift region 622, and the NBL in the LDMOS devices of existing method is to the problem of the low avalanche breakdowns of highly doped PBL Improved by inserted HV deep N-wells N-type buffer layer 618.Equally, deep trench isolation structure is (invisible in Fig. 6, but under Text is further described) can be coupled to NBL 614 and the Jing isolation channels with N-type bottom and side can be formed for LDMOS devices, So as to further improve isolation.P-n junction 626 is arranged as before.It is said that the p-type implantation step of Fig. 6 can be by p-type embedded Layer or PBL 628 are inserted into N-shaped chain type implanting portion.
At this stage in process, extra deep trench isolation structure can be formed about in LDMOS devices.In an arrangement In, deep trench or " DT " region can be formed at electricity by oxide or interior other dielectric formations for being lining in groove, wherein P+ materials Areas of dielectric inner side and extend to p epitaxial layers.In the second arrangement, DT structures can further include and interior be lining in groove and to downward Reach the N+ materials of N embedded layers, and in addition, N+ materials are formed as isolating with P+ materials by dielectric substance, and extend To NBL layers with from N-type slot structure.The use of DT structures provides excellent electric isolution for LDMOS devices.Top side contact can be formed To allow groove to be electrically coupled to current potential for further isolation and Noise measarement.
Fig. 7 describes in cross a part for the deep groove structure 700 that can be used together with arrangement.Deep groove structure 700 are formed after PBL implantation in figure 6 is completed.For example, deep groove structure can be wherein dielectric liner in each side And P+ materials 758 are formed in core and extend to the groove of p epitaxial layers 712.In the arrangement of Fig. 7, deep groove structure Further include N+ materials 754.Dielectric portion 756 isolates N+ parts with P+ materials 758.N+ materials 754 extend through STI 752nd, N trap materials 722/724, PBL 728, deep N-well 718 and contact N embedded layers NBL 714.P+ materials 758 extend through institute There are these layers and extend in P-epi layers 712 or through P-epi layers 712 to contact substrate P 710.Deep trench 700 is with cross section Show but can be centered around the LDMOS devices shown in each figure above to extend to form slotted channel, and with N+ materials 754 N embeddeds layer 714 can form N-type isolation channel.
The STI layer 752 for being formed in the figure 7 also serves as the part of LDMOS devices.In fig. 8, it is illustrated in from Fig. 6's LDMOS devices 800 after consecutive steps (it is included in drift region top and forms STI insulators 852).In fig. 8, LDMOS devices 800 include STI layer 852, JFET diffusion parts 824, Driftdiffusion portion 822 (it is N-type diffusion part), P-epi materials 816 and double delayed by what PBL 828 and HV deep N-wells buffer 818 (it is formed at the tops of N-shaped embedded layer NBL 814) were formed Device, p-type epitaxial layer 812 and P type substrate 810 and knot 826 are rushed, it is all arranged as described above.In alternative arrangement, can Replace STI layer 852 and use LOCOS isolation parts.
Fig. 9 describes LDMOS devices 900 and illustrates to form the extra process step of device.In fig .9, perform The chain type of the first p-type dopant is implanted into the dopant level in the D well depth upper/lower agent structures for repairing LDMOS devices. Resist layer 947 is formed using photomask, resist and pattern process.It is that 971 implantation is opened that a succession of p-type is implanted into number Begin, such as from～3 × 1012Atom/cm2To～8 × 1012Atom/cm2Implant dosage under using boron is as dopant and makes With the implantation energy of～1MeV to 2MeV.This is implanted in p-epi layers 916 to form diffusion zone 954 and form deep top and (spreads Portion 956)/bottom (diffusion part 954) body region a part.After the implantation that numbering is 971, the second implantation 973 is performed. In this ion implanted step, diffusion zone 956 is previously formed above diffusion zone.In an arrangement, this second implantation It is to use boron implantation to perform, wherein implantation energy is between 400KeV to～800KeV, wherein implant dosage is between 8 × 1012 Atom/cm2To～5 × 1013Atom/cm2Between.Main diffusion portion 954 is reached deep down into for D traps and PBL to be linked, and upwards Go deep into main diffusion portion 956 for building distributed charge to the N trap JFET regions 924 close to the bottom corner regions of STI 952 Equilibrium region is realizing horizontal JFET RESURF.In fig .9, substrate 910, p epitaxial layers 912, NBL 914, deep N-well buffer 918 and PBL 928, N traps drift region 922 is all arranged as described above.
Figure 10 is illustrated in for the next consecutive steps for forming LDMOS devices 1000.Show in Fig. 10 Extra chained ion is implanted into altogether.Altogether implantation and the deep upper/lower main body in Fig. 9 are implanted into shared identical Resist patterns and light for this Mask realizes shallow main body and effective channel region to form extra diffusion region domain 1058.This control of extra diffusion region domain 1058 is leaned on It is bordering on the sublist face of the field-effect of substrate surface and this channel regions of CHANNEL RESURF in approaching device drain side Charge balance, the sublist surface charge balance arrives close by the shallow main body of D traps (from the p-type ion of common implantation diffusion part 1058) The top section of the HV deep N-wells of the side wall of STI 1052 is adjusted.The raceway groove resurf and JFET of the arrangement of subject application Using for resurf diffusion concepts solves the problems, such as channel hot carrier, so as to allow that existing side is not formed using short channel devices The channel hot carrier of method.Equally, more uniform electric current flowing during JFET zone resistances are due to this region and reduce.In Figure 10 Ion implanted step 1075 and 1076 is performed using the p-type and N-shaped implanting ions that are implanted to altogether in diffusion zone 1058, N-type area is used as the part in device N-shaped source and altogether implanting p-type region forms the shallow main body of device D traps in diffusion zone 1058.Two plants To enter may be adjusted to the effective channel region of control LDMOS devices.In exemplary altogether implantation step 1075,1075 are shown as P-type implantation can use 1 × l013Atom/cm2To～3 × 1014Atom/cm2Implant dosage 60Kev to 260KeV implantation Boron is used to perform as dopant atom under energy.1076 are implanted into altogether for N-shaped, and arsenic can be in～2 × l013Atom/cm2To～ 1×l015Atom/cm2Implant dosage under with the implantation energy implantation of～20KeV to～220KeV.These common implantation step shapes Into the shallow main diffusion region 1058 of device, reduce so as to be directed to formed LDMOS devices 1000 at the surface of channel region Electric field.
Drift resurf, JFET resurf and raceway groove resurf implantation steps are concatenated together improving from device drain electrode To drift region and to JFET and channel region device Electric Field Distribution for provide high-performance LDMOS device.
Driftdiffusion portion in remaining element STI 1052, JFET diffusion parts 1024, N traps illustrated in Figure 10 1022nd, p embeddeds layer 1028, HV deep N-wells buffer 1018, n embedded layers NBL 1014, p epitaxial layers 1012, substrate 1010 and Arrange as before.Main diffusion portion 1054,1056 and 1058 provides extra property in the body region of p epitaxial layers 1016 Can, the body region forms the D traps of LDMOS devices.As described below, the source contact and body contact of LDMOS devices Will be formed in this D well areas top.Knot 1026 is formed between D well areas and N well region in p-epi materials 1016.
Figure 11 describes the continuous of the grid to form LDMOS devices 1100 and gate-dielectric in another cross-sectional view Step.Gate dielectric layer 1180 (it typically is silica, hafnium oxide or other insulating materials and between～1nm with Thickness between～45nm) it is formed on the top of substrate 1110 by known method.By the desired grid electricity of LDMOS devices Press specified (such as grid voltage 1.5V, 3.3V, 5V and 12V) and determine the selection of gate dielectric material and thickness.Formed In one arrangement of the aspect of subject application, the extra NMOS gate and PMOS gate-dielectrics in the other parts of substrate 1110 Layer or gate insulator (not showing in Figure 11) can make of similar material and similar thickness, and can in time with LDMOS gate Pole dielectric 1180 is formed simultaneously.Alternatively, PMOS and NMOS gate dielectric can be independently of with different materials and/or thickness LDMOS grid electrode dielectric and formed.
Again referring to Figure 11, grid 1182 is formed on the top of gate-dielectric 1180.Grid 1182 is generally by polysilicon (being referred to as polysilicon) is formed.Polysilicon deposition is in gate dielectric layer top and can also be deposited on NMOS and PMOS grid Pole dielectric layer (displaying) top forms NMOS and PMOS grid structures with other places on substrate 1110.
Driftdiffusion portion in remaining element STI 1152, JFET diffusion parts 1124, N traps illustrated in Figure 11 1122nd, p embeddeds layer 1128, HV deep N-wells buffer 1118, n embedded layers NBL 1114, p epitaxial layers 1112, substrate 110 and Knot at 1126 is arranged as before.D traps or main diffusion portion 1154,1156 and common implanted region 1158 are in p epitaxial layers Extra performance is provided in 1116 body region, the body region forms the D traps of LDMOS devices.As described below, The source contact and body contact of LDMOS devices will be formed in this D well areas top.Knot 1126 is formed at p-epi materials 1016 In D well areas and N well region between.
The LDMOS devices 1200 that Figure 12 describes after additional process steps in another cross-sectional view.Grid photoresist Agent pattern (not illustrating for simplicity) is patterned when applied to the top of grid 1282 and for etch process.By Know that engraving method removes the non-required part of any non-wanted grid polycrystalline silicon and underlying gate dielectric.Then grid is also removed Photoresist.Be placed in Semiconductor substrate 1210 other in substrate 1210 are local and sightless portion in fig. 12 Point in any NMOS and/or PMOS transistor grid structure can when LDMOS grid electrode polysilicon 1282 is formed synchronization pattern Change.In some arrangements for the additional aspect for forming subject application, replacing grid (such as metal gates) can process step after a while Replace polysilicon gate 1282 in rapid place.As shown in fig. 12, gate lateral wall distance piece 1288 is then formed by insulator, example Such as oxide skin(coating), oxynitride layer or nitride layer.Gate spacer 1288 can be by oxide deposition or by other known Technology is formed.Gate spacer then passes through anisotropic etch step and is formed.With regard to other steps described herein, can The synchronous grid for forming the NMOS and/or PMOS device made simultaneously in the other parts of sightless substrate 1210 in fig. 12 Structure.
Again referring to Figure 12, it is implanted into by using low-voltage PMOS N traps and forms shallow N traps 1290, shallow N traps 1290 generally exists Formed before gate oxide and grid polycrystalline silicon processing step.In exemplary placement, for this trap of LDMOS drain regions 1290 also form simultaneously with the N well region formed for other the local CMOS devices being made on substrate 1210.
Further again referring to Figure 12, P+ body contacts (being labeled as B), N+ source contacts are formed in additional process steps (being labeled as S) and drain contact (being labeled as D).In arrangement, contact implantation step is also performed to be formed for being located at substrate On other local CMOS devices source contact and drain contact.Also form the contact G to grid.
The cross section shown in Figure 12 illustrates essentially completed LDMOS devices 1200.LDMOS devices 1200 are included Body contact B, source contact S, gate contacts G and drain contact D, by HV deep N-wells buffer 1218 and p-type embedded layer PBL The drift region resurf implanting portions 1222 of 1228 double bufferings for being formed, formation drift and JFET resurf diffusion parts, Up/down main diffusion portion 1256,1254 in 1224, D well areas, and the raceway groove resurf diffusions formed by common implantation technique Portion 1258.NBL 1214, p epitaxial layers 1212 and substrate 1210 are all arranged as before.
In operation, channel region 1285 is formed between the source electrode N+ regions for being labeled as " S " and between p-type D well area Below the area of grid between the p-n junction 1226 between N-shaped drift region.When the current potential more than threshold value is applied to gate terminal During G, inversion region is formed and carrier can advance from the N+ source regions for being labeled as S across raceway groove and advance to drift region In, and then float to the N+ drain regions D below STI insulators 1252.By chained ion implantation step as described above Formed the various doped diffusion part in raceway groove, body region and drift region using reduction surface field effect provide " resurf " device, increase breakdown voltage BVdss and provide rationally low drain-to-source conducting resistance Rdson to realize high property Can ldmos transistor.
Figure 13 describes the LDMOS devices 1300 for completing in another cross-sectional view, LDMOS devices 1300 be with CMOS half The MOS transistor formed in conductor manufacturing process builds simultaneously.Figure 13 illustrate formed on substrate simultaneously CMOS device and The ability of both LDMOS devices.LDMOS devices 1300 include body contact B, source contact S, gate contacts G and drain contact D, the double buffering formed by HV deep N-wells buffer 1318 and p-type embedded layer PBL 1328 forms drift and JFET Up/down main diffusion portion 1356 in the drift region resurf implanting portions 1322,1324, D well areas of resurf diffusion parts, 1354, and the raceway groove resurf diffusion parts 1358 formed by common implantation technique.P-n junction 1326 is formed at p-epi regions 1316 In D well areas and N well region between.Deep trench isolation structure 1301 passes through the n-type material for extending to and contacting NBL 1314 1362 and extend to the p-type material 1364 of substrate 1310 and formed, and comprising dielectric area 1364 with by bi-material each other every From.In low voltage cmos region 1302, PMOS transistor is shown as the source that mark is being formed with shallow N traps 1372 Pole contact, the grid for being labeled as G1 and the drain contact for being labeled as D1, with single N+N traps contact (not showing in Figure 13). As described above, some processing steps to form LDMOS devices after chain type implantation can be being formed for LDMOS dresses Put and both CMOS devices structure when use, so as to realize that two kinds of device while system is carried out in substrate 1310 Make.For example, polysilicon gate material G, G1 are formed simultaneously for two kinds of device.In this way, highly integrated electricity Road device (for example, LDMOS high-side driver and the associated high voltage CMOS control circuitry for controlling the driver) can It is formed in the single integrated circuit on silicon substrate.
Figure 14 illustrate in flow charts for forming exemplary placement in LDMOS devices method the step of. In Figure 14, method is started at step 1401 with the p epitaxial layers above substrate P.At step 1403, by the way that execution is ion implanted The blanket of N-type embedded layer covers to be formed.In instances, it is ion implanted using very high concentration, uses up to 5 × 1015Atom/cm2n The implant dosage of type dopant.In one approach, blanket is formed in the case where mask is not needed and covers N-shaped embedded layer.Replacing In for method, using mask layer and complete to be selectively implanting.In this method, after a while formed contact NBL material deep N structures with N-shaped groove is completed around LDMOS devices.
At in fig. 14 the step of 1405, the in-line arrangement epitaxial layer of P materials is formed to provide for LDMOS device (deep N-wells Region and body region) and CMOS device for can be formed on substrate simultaneously basic material.
At step 1407, perform chain type N-shaped and be ion implanted.The first implantation in the chain is with from 1 × 1012Atom/cm2 To 3 × 1012Atom/cm2Dosage use phosphorus as dopant atom under the implantation energy of 2MeV to 3MeV.This implantation is formed High voltage deep N-well buffer layer, as described above.Then n-type dopant (such as phosphorus) is reused and with from 2 × l012It is former Son/cm2To～5 × l012Atom/cm2Implant dosage perform under the energy level from 600KeV to～2MeV in N-shaped chain second Implantation.This implantation forms the diffusion part of the resurf controls of drifting about for device in drift region.Next, for example using arsenic with From l × l012Atom/cm2To～9 × l012Atom/cm2Dosage perform N-shaped under the energy level from～100KeV to～350KeV The 3rd N-shaped in chain be implanted into form JFET regions in diffusion part, as described above.These are used above double buffering Implanted region improves the performance that Jing cascades resurf LDMOS devices.
At step 1409, formation is inserted into the p embedded layers being implanted into by N-shaped chain type in the N-shaped diffusion part for being formed.This p Type embedded layer or PBL are formed by being ion implanted for boron, such as in the implantation energy from～800KeV to～2.5MeV Under, from～3 × l012Atom/cm2To～8 × l012Atom/cm2.PBL layers are overlie in HV deep N-well N-type buffer areas with shape Design into the double buffering structure and drift region resurf for ldmos transistor, as described above.
At in fig. 14 the step of 1411, isolation structure is formed.If be formed at step 1403 in blanket covers step The N-shaped embedded layer NBL of formation, then the deep trench isolation structure for for example being shown in Fig. 7 or Figure 13 can be used.Substituting In method, if using mask during NBL at forming step 1403, then isolation structure can be deep n contact with hidden with N-shaped Buried floor forms groove around the area of LDMOS devices together.
As shown in fig. 14, method then transitions to the step 1501 in Figure 15.
In fig .15, flow chart continues.Figure 15 shows remaining step for forming the method for ldmos transistor.In step At rapid 1501, the shallow trench isolation for ldmos transistor or sti region are formed.Meanwhile, can in other regions of substrate shape Into for CMOS transistor extra sti region, as described above.At step 1503, perform first and go here and there p-type implantation with complete Into the Part I or the deep upper/lower body region of LDMOS devices of D traps.Lower body portions are used to connect D traps and PBL Connect, and upper body part is used to support JFET resurf near the bottom of the STI corner regions of LDMOS devices.With 3 × 1012 Atom/cm2To～8 × l012Atom/cm2Between implant dosage under the implantation energy of 1MeV to 2MeV (such as) use boron The first implantation is performed as dopant atom；Then with from～8 × l012Atom/cm2To～5 × l013Atom/cm2Implantation Dosage uses boron to perform the implantation of the second p-type with the implantation energy of～400KeV to～800KeV.
After step 1503, continuously perform second using identical D traps implantation mask layer and be implanted into chain 1505 altogether, for example, use Boron is as p-type dopant and using arsenic as n-type dopant.With the implantation energy from～60KeV to～260KeV and with from～l ×l013Atom/cm2To～3 × l014Atom/cm2Implant dosage perform p-type implantation；With from～20KeV to～220KeV Implantation energy and from～2 × 1013Atom/cm2To～1 × 1015Atom/cm2Implant dosage perform N-shaped implantation.Such as institute above Description, altogether implantation is formed and has the shallow main body and effective channel region designed for the raceway groove resurf of LDMOS devices.
In the arrangement of subject application, drift resurf, JFET resurf and raceway groove resurf is ion implanted level and is associated in one Rise to improve from device drain-drift region to JFET and channel region device Electric Field Distribution to realize the high property of LDMOS devices Energy.
At in fig .15 the step of 1507, method continues.At this step, for forming remaining structure of LDMOS devices While (such as gate-dielectric, grid conductor, source electrode, body region and drain region) processing step can with substrate On other places make similar steps of CMOS device (such as PMOS and nmos pass transistor) and perform simultaneously.In this way, it is high Degree IC apparatus can be made into the LDMOS devices for incorporating each arrangement.At in fig .15 the step of 1509, illustrated side Method terminates.After the method shown in Figure 14 and 15 is performed, semiconductor fabrication process is continuing with conventional steps (comprising silicon Compound formation, interlayer dielectric, conducting body and contact are formed, metal deposit and patterning etc.) and structure is connected into metal Change pattern, with using top conductive layer (such as metallic conductor) by the source electrode of LDMOS devices, main body, drain electrode and gate terminal and The source electrode of CMOS device (if any), drain electrode and gate terminal are coupled to various signals.
Method using being shown in Figure 14 and 15, can be using only with two additional masks levels, (one for N-shaped drift Moving region and one is used for D traps or body region) standard CMOS semiconductor technique obtain the LDMOS with superior function and fill Put.Chain type implantation is performed in consecutive steps using single mask.For the N-shaped embedded layer and p of the double buffering in arrangement Type embedded layer can be formed in the case where mask is not used in blanket covers and is ion implanted, and as described above, system be reduced whereby Cause this.
The exemplary LDMOS device formed using double buffering and Jing cascade resurf diffusion arrangements has obtained performance meter Amount, as described above.Described device is compared with the device obtained using existing method (such as device demonstrated in Figure 1) When show superior breakdown voltage and reduced resistance.
The LDMOS devices obtained using arrangement as described above and structure are illustrated compares specific conducting with existing method The average reduction of resistance 32.6%, and meet auto industry guide in terms of the maximum Id transformations of 10 years DC.
From from the viewpoint of manufacturing cost and complexity, there is double buffering and Jing cascade resurf diffusion parts for being formed The method of LDMOS devices relatively low mask count LDMOS technique is provided.Additionally, the device obtained using the arrangement of subject application Conducting resistance Rdson is less than known existing method.
Can modify in described embodiment, and other embodiments are possible in the range of claims. For example, also can modify in terms of the number in terms of the order of step and in step.
1. a kind of LDMOS devices, it includes：
At least one drift region, it is placed in a part for Semiconductor substrate and is doped to the first conductivity-type；
At least one isolation structure, it is located at the surface of the Semiconductor substrate and is positioned at least one drift region A part in；
D well areas, it is located in another part of the Semiconductor substrate, is doped to the second conductivity-type and adjacent to described A part at least one drift region and position, and the drift region forms described with the joining of the D well areas Knot between one conductivity-type and second conductivity-type；
Grid structure, it is placed on the surface of the Semiconductor substrate and overlies the one of channel region and the isolation structure On part, the grid structure is comprising the gate dielectric layer above the channel region and overlies grid electricity Jie Gate conductor materials in matter；
Source contact regions, it is placed on the surface of the D well areas and adjacent to the side of the channel region, the source electrode Contact region is doped to first conductivity-type；
Drain contact region, its be placed in the shallow diffusion trap on the surface of the drift region and the neighbouring isolation structure and It is spaced apart with the channel region by the isolation structure, the drain contact and the shallow diffusion trap are doped to described the One conductivity-type；And
Double buffering region, it is included：First embedded layer, it is located at below the D well areas and the drift region and quilt It is doping to second conductivity-type；And the second high voltage deep diffusion layer, it is located at below the first embedded layer and quilt It is doping to first conductivity-type.
2. LDMOS devices according to claim 1, wherein first conductivity-type is N-shaped and described second conductive Property type be p-type.
3. LDMOS devices according to claim 1, it is further included：
First N-shaped resurf diffusion zones, it is located in the drift region；And the second N-shaped JFET resurf diffusion zone, It is located in the drift region, neighbouring with the knot of the D well areas and on the first N-shaped resurf diffusion zones Face.
4. LDMOS devices according to claim 3, it further includes to be spread near the 3rd N-shaped of the channel region Portion.
5. LDMOS devices according to claim 1, it is further included：First p-type diffusion zone, it is located at the D traps The neighbouring first embedded layer in region, forms deep sub-body diffusion part；And the second p-type diffusion zone, it is located at the D The neighbouring knot with the drift region, forms upper body diffusion part in well area.
6. LDMOS devices according to claim 5, it further includes to be located at the source contact regions and the raceway groove The 3rd p-type diffusion zone in region.
7. LDMOS devices according to claim 1, wherein the Semiconductor substrate further includes second electric conductivity The epitaxial layer of type.
8. LDMOS devices according to claim 7, wherein the LDMOS devices further include the second embedded layer, institute State the second embedded layer and be formed at below high voltage deep trap and as the implanted region of first conductivity-type and be described In the epitaxial layer in Semiconductor substrate.
9. LDMOS devices according to claim 8, it further includes deep isolation structure, the deep isolation structure and institute State D well areas to be spaced apart and pass through the first embedded layer, the high voltage deep diffusion layer from the surface of the substrate And extend and contact with the Semiconductor substrate through the epitaxial layer.
10. LDMOS devices according to claim 8, it further includes deep trench isolation structure, the deep trench isolation Structure is spaced apart with the D well areas and extends through the first embedded layer and the height from the surface of the substrate Voltage deep trap and extend in the second embedded layer.
11. LDMOS devices according to claim 10, wherein the deep trench isolation structure is further included and described the The material of first conductivity-type of two embedded layer physical contact.
A kind of 12. methods for forming LDMOS devices, methods described includes：
It is square into epitaxial layer on the semiconductor substrate；
The first of first conductivity-type is formed by implant impurity in the epitaxial layer square on the semiconductor substrate Embedded layer, the epitaxial layer and the Semiconductor substrate are doped to the second conductivity-type；
The in-line arrangement epitaxial layer of second conductivity-type is formed above the embedded layer；
Perform first of first conductivity-type in the implantation of the first chain type to be ion implanted to form high voltage deep trap buffering Device region；
Perform being ion implanted for second conductivity-type and be placed in the high voltage deep trap buffer areas with drift to be formed The the second embedded layer moved between region, the high voltage deep trap buffer areas and the second embedded layer form double buffering Device region；
The area of isolation in the trap of first conductivity-type is formed at the surface of the Semiconductor substrate；
Over the substrate side's deposition gate-dielectric, in the gate-dielectric disposed thereon grid conductor, and then etches The grid conductor and the gate-dielectric are forming the grid structure overlie on channel region；And
Implant impurity is located at institute to form the source region that is spaced apart with the grid structure by the channel region and be formed The drain region stated in drift region and be spaced apart with the grid structure by the area of isolation.
13. methods according to claim 12, wherein first conductivity-type is N-shaped and the second electric conductivity class Type is p-type.
14. methods according to claim 13, wherein perform the first chain type implantation further including：Perform described The second of one conductivity-type is ion implanted to form the drift resurf diffusion parts in well area, and execution described first The 3rd of conductivity-type is ion implanted and is located in the well area and on the drift resurf diffusion parts with being formed JFET resurf diffusion parts.
15. methods according to claim 13, further include：After the area of isolation is formed, by following behaviour Make the second chained ion implantation for performing second conductivity-type：Perform the first plant of the second chained ion implantation Enter, comprising the impurity for being implanted into second conductivity-type forming a D well areas bottom diffusion part；And execution described second Second implantation of chained ion implantation, comprising the impurity for being implanted into second conductivity-type being formed in a D well regions The 2nd D traps upper diffusion domain above the diffusion part of domain bottom.
16. methods according to claim 15, it further includes to perform extra chain type implantation with common implantation described first The ion of both conductivity-type and second conductivity-type in the channel region forming shallow resurf diffusion regions Domain.
17. methods according to claim 13, it is further included：After the second embedded layer is formed, formed Deep trench isolation structure, the deep trench isolation structure extends through the second embedded layer from the surface of the substrate And through the first embedded layer physically contacting with the Semiconductor substrate.
A kind of 18. integrated circuits, it includes：
LDMOS devices, it is included：
Source contact regions, it is placed on the surface of the D well areas and at the side of the neighbouring channel region, described Source contact regions start to be doping to first conductivity-type；
Double buffering region, it is included：First embedded layer, it is located at below the D well areas and the drift region and quilt It is doping to second conductivity-type；And the second high voltage deep diffusion layer, it is located at below the first embedded layer and quilt It is doping to first conductivity-type；And
At least one mos device, it is formed in the Semiconductor substrate and is spaced apart with the LDMOS devices.
19. integrated circuits according to claim 18, wherein at least one mos device further includes PMOS crystal Pipe.
20. integrated circuits according to claim 18, wherein first conductivity-type is N-shaped and described second conductive Property type be p-type.
CN201580042187.4A 2014-08-07 2015-08-07 Method and apparatus for LDMOS device with cascaded RESURF implants and double buffers CN106663699B (en)
CN106663699A true CN106663699A (en) 2017-05-10
CN106663699B CN106663699B (en) 2020-06-05
CN107564816B (en) * 2016-06-30 2020-05-08 中芯国际集成电路制造(上海)有限公司 LDMOS transistor and forming method thereof
US20120037984A1 (en) * 2010-08-12 2012-02-16 Ipgoal Microelectronics (Sichuan) Co., Ltd. LDMOS Structure
US20140124857A1 (en) * 2012-11-05 2014-05-08 Jae-June Jang Semiconductor device and method of forming the same
EP0562271B1 (en) 1992-03-26 1998-01-14 Texas Instruments Incorporated High voltage structure with oxide isolated source and resurf drift region in bulk silicon
WO2016022975A1 (en) 2016-02-11
KR101298339B1 (en) 2013-08-20 High-voltage bipolar-cmos-dmos integrated circuit devices and modular methods of forming the same
CN102623489B (en) 2014-11-26 Semiconductor device and method of manufacturing the same