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1、Prepared By SMIC FAB 4 DiffusionIMP IntroductionPrepared By SMIC FAB 4 DiffusionOutline Why implant? Major applications. Basic introduction to Implanters Typical subsystems introduction Process concerns Lesson learn Q basic transistor structure B= NMOS channel threshold voltage adjust; sets n-channe
2、l Vt (or Vp) C= NMOS LDD; hot carrier suppression D= p-well (“tub”) structure; contains NMOS transistors E= p-type “channel stop” for p-well; intra-well (E) and inter-well (E) field isolation F= PMOS source/drain; basic transistor structure G= PMOS buried-channel threshold voltage adjust; sets p-cha
3、nnel Vt (Vp) H= PMOS “punchthrough” suppression I = n-well (“tub”) structure; contains PMOS transistors J= n-type “channel stop” for n-well; intra-well (J) and inter-well (J) field isolation K= NMOS “punchthrough” suppression L= PMOS LDD; hot carrier suppression M= n+ polysilicon gate doping; improv
4、es conductancePrepared By SMIC FAB 4 DiffusionCategoriesHEI (High Energy Implanter) MCI (Medium Current Implanter)HCI (High Current Implanter)LEI (Low Energy Implanter)Major Equipment ManufacturersAMAT, Axcelis (Eaton), Nissin, VarianImplanter FundamentalsPrepared By SMIC FAB 4 DiffusionImplanter Fu
5、ndamentalsSpeciesEnergyDose B (Diffused Well) P (Diffused Well) B (Retrograde Well) P (Retrograde Well) 100- 200KeV 100- 200KeV 150- 800KeV 400- 1500KeV2E12-2E13 2E12-2E13 4E12-5E13 4E12-5E13Typical Well ImplantsTypical Vt Adjustment Elemental and metallic contamination Energy contamination; Dose sh
6、ift; Charging; Channeling; Shadowing and undercutKey Ion Implantation Process Concerns Prepared By SMIC FAB 4 DiffusionImplanter FundamentalsnOrientationnBasic sub-systems of the ion Implanter1.Ionization 2.Extraction Acceleration 3.Beam control 4.Analysis 5.Monitoring 6.Control of wafer charging 7.
7、ScanningAxcelis NV-GSDPrepared By SMIC FAB 4 DiffusionKey ParametersSpecies (What type of particles to be used)Energy (Ions final kinetic energy)Dose (Quantity of ions implanted into a unit area)Implant Angle (Beam direction vs. crystal orientation)All the above parameters are simulated and predefin
8、ed in process design period. And are very critical to devices performance and reliability.Key Ion Implantation Process Concerns Prepared By SMIC FAB 4 DiffusionImplanter FundamentalsAxcelis GSD/HEPrepared By SMIC FAB 4 DiffusionImplanter Fundamentals Sources: IonizationnAtoms for Ionization from a G
9、as SourcePrepared By SMIC FAB 4 DiffusionImplanter Fundamentals Sources: IonizationnDefinitionnIon sourcenSource atomsGasSolidTypical ion source (enhanced source)Beamline Schematic GSD200/EE 160/180kV ImplanterPrepared By SMIC FAB 4 DiffusionImplanter Fundamentals Sources: IonizationnAtoms for Ioniz
10、ation from a Solid Source GSD Series Dual VaporizerVaporizer assemblyGases versus solidsPrepared By SMIC FAB 4 DiffusionImplanter Fundamentals Sources: IonizationnIonizationPrepared By SMIC FAB 4 DiffusionImplanter Fundamentals Sources: IonizationnEffects of ionizationnCharge states, single, double,
11、 should it drift downstream, it will be repelled by the post-accel suppression electrode.Prepared By SMIC FAB 4 DiffusionImplanter Fundamentals Suppression ElectrodesnSecondary electrons in the gap region(s): X-radiation and beam BlowupGap region at the extraction electrode assembly (dual slot elect
12、rode)Gap region at the post acceleration electrode assembly Prepared By SMIC FAB 4 DiffusionSpace Charge and Beam TransportPrepared By SMIC FAB 4 DiffusionSpace Charge and Beam TransportnHow do we “reduce net space charge” caused by having too many ions around?nAdding electrons to the beam, especial
13、ly in regions where the beam current density is highest (like in the beamguide), will cancel the effects of space chargenAnd where do these extra electrons come from?Injectedexternal plasma source can introduce electrons to the beamBeam generated beam collisions with background gas can produce elect
14、ronsPrepared By SMIC FAB 4 DiffusionSpace Charge and Beam TransportnWe can easily inject electrons where there is no magnetic fieldat the end of the beamline (in the endstation process chamber) this works perfectlya plasma flood gun (PEF) is ideal - its more than just a wafer charge control toolnWe
15、cant easily inject electrons where there is a magnetic fieldin the beamguide (inside the analyzer magnet) is where we need the electrons mostnWe already have beam generated electronswhat we need is a way to make more of themraise the pressure in the beamguide - helps somewhat, but not enough and a w
16、ay to make them last longerPrepared By SMIC FAB 4 DiffusionImplanter Fundamentals Species SelectionnSpecies ControlPurpose:To choose the one ion species we want Example:Boron TrifluoridePrepared By SMIC FAB 4 DiffusionImplanter Fundamentals Species SelectionnBeam Spectrum for BoronNOTE: There are two different isotopes of boron: 10B+ and 11B +. There are four times more 11B+ occurring in nature than 10B+.Prepared By SMIC FAB 4 Di
