Ion Implantation离子注入.ppt

1、Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,1,Chapter 8Ion Implantation,Hong Xiao, Ph. D. www2.austin.cc.tx.us/HongXiao/Book.htm,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,2,Objectives,List at least three commonly used dopants Identify three doped areas Describe the advant

2、ages of ion implantation Describe major components of an implanter Explain the channeling effect Relationship of ion range and ion energy Explain the post-implantation annealing Identify safety hazards,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,3,Ion Implantation,Introduction Safety Ha

3、rdware Processes Summary,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,4,IC Fab,Wafer Process Flow,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,5,Introduction: Dope Semiconductor,What is Semiconductor? Why semiconductor need to be doped? What is n-type dopant? What is p-type d

4、opant?,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,6,Introduction,Dope semiconductor Two way to dope Diffusion Ion implantation Other application of ion implantation,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,7,Dope Semiconductor: Diffusion,Isotropic process Cant independe

5、ntly control dopant profile and dopant concentration Replaced by ion implantation after its introduction in mid-1970s.,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,8,Dope Semiconductor: Diffusion,First used to dope semiconductor Performed in high temperature furnace Using silicon dioxide

6、 mask Still used for dopant drive-in R&D on ultra shallow junction formation.,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,9,Dopant Oxide Deposition,Si Substrate,SiO2,Deposited Dopant Oxide,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,10,Oxidation,Si Substrate,SiO2,Hong Xiao,

7、 Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,11,Drive-in,Si Substrate,SiO2,Doped junction,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,12,Strip and Clean,Si Substrate,SiO2,Doped junction,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,13,Dope Semiconductor: Ion Implantation,Us

8、ed for atomic and nuclear research Early idea introduced in 1950s Introduced to semiconductor manufacturing in mid-1970s.,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,14,Dope Semiconductor: Ion Implantation,Independently control dopant profile (ion energy) and dopant concentration (ion c

9、urrent times implantation time) Anisotropic dopant profile Easy to achieve high concentration dope of heavy dopant atom such as phosphorus and arsenic.,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,15,Misalignment of the Gate,Gate Oxide,n-Si,n-Si,p+ S/D,p+ S/D,Metal Gate,Metal Gate,Aligne

10、d,Misaligned,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,16,Ion Implantation, Phosphorus,Poly Si,n+,P-type Silicon,n+,SiO2,P+,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,17,Comparison of Implantation and Diffusion,PR,SiO2,Si,Si,Ion implantation,Diffusion,Doped region,Juncti

11、on depth,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,18,Comparison of Implantation and Diffusion,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,19,Ion Implantation Control,Beam current and implantation time control dopant concentration Ion energy controls junction depth Dopant

12、 profile is anisotropic,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,20,Applications of Ion Implantation,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,21,Other Applications,Oxygen implantation for silicon-on-insulator (SOI) device Pre-amorphous silicon implantation on titanium

13、 film for better annealing Pre-amorphous germanium implantation on silicon substrate for profile control .,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,22,Some Fact about Phosphorus,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,23,Some Fact about Arsenic,Hong Xiao, Ph. D.,www2

14、.austin.cc.tx.us/HongXiao/Book.htm,24,Some Fact about Boron,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,25,Stopping Mechanism,Ions penetrate into substrate Collide with lattice atoms Gradually lose their energy and stop Two stop mechanisms,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao

15、/Book.htm,26,Two Stopping Mechanism,Nuclear stopping Collision with nuclei of the lattice atoms Scattered significantly Causes crystal structure damage. electronic stopping Collision with electrons of the lattice atoms Incident ion path is almost unchanged Energy transfer is very small Crystal struc

16、ture damage is negligible,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,27,Stopping Mechanism,The total stopping power Stotal = Sn + Se Sn: nuclear stopping, Se: electronic stopping Low E, high A ion implantation: mainly nuclear stopping High E, low A ion implantation, electronic stopping

17、 mechanism is more important,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,28,Stopping Mechanisms,Random Collisions (S=Sn+Se),Channeling (SSe),Back Scattering (SSn),Ion,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,29,Stopping Power and Ion Velocity,Nuclear Stopping,Electronic

18、Stopping,I,II,III,Ion Velocity,Stopping Power,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,30,Ion Trajectory and Projected Range,Projected Range,Ion Trajectory,Collision,Ion Beam,Vacuum,Substrate,Distance to the Surface,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,31,Ion Proj

19、ection Range,ln (Concentration),Projected Range,Substrate Surface,Depth from the Surface,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,32,0.010,0.100,1.000,10,100,1000,Implantation Energy (keV),Projected Range (mm),B,P,As,Sb,Projected Range in Silicon,Hong Xiao, Ph. D.,www2.austin.cc.tx.u

20、s/HongXiao/Book.htm,33,0.00,0.20,0.40,0.60,0.80,1.00,1.20,Si,SiO2,Si3N4,Al,Mask Thickness (micron),Sb,As,P,B,Barrier Thickness to Block 200 keV Ion Beam,PR,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,34,Implantation Processes: Channeling,If the incident angle is right, ion can travel lo

21、ng distance without collision with lattice atoms It causes uncontrollable dopant profile,Very few collisions,Lots of collisions,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,35,Channeling Effect,Channeling Ion,Collisional Ion,Lattice Atoms,q,Wafer Surface,Hong Xiao, Ph. D.,www2.austin.cc.

22、tx.us/HongXiao/Book.htm,36,Post-collision Channeling,Collisional,q,Wafer Surface,Collisional,Channeling,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,37,Post-collision Channeling,Collisional,Collisional,Channeling,Dopant Concentration,Distance from surface,Hong Xiao, Ph. D.,www2.austin.cc

23、.tx.us/HongXiao/Book.htm,38,Implantation Processes: Channeling,Ways to avoid channeling effect Tilt wafer, 7 is most commonly used Screen oxide Pre-amorphous implantation, Germanium Shadowing effect Ion blocked by structures Rotate wafer and post-implantation diffusion,Hong Xiao, Ph. D.,www2.austin.

24、cc.tx.us/HongXiao/Book.htm,39,Shadowing Effect,Polysilicon,Substrate,Doped Region,Shadowed Region,Ion Beam,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,40,Shadowing Effect,Polysilicon,Substrate,Doped Region,After Annealing and Diffusion,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Boo

25、k.htm,41,Q & A,Why dont people use channeling effect to create deep junction without high ion energy?,Ion beam is not perfectly parallel. Many ions will start to have a lot of nuclear collisions with lattice atoms after they penetrating into the substrate. Some ions can channel deep into the substra

26、te, while many others are stopped as the normal Gaussian distribution.,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,42,Damage Process,Implanted ions transfer energy to lattice atoms Atoms to break free Freed atoms collide with other lattice atoms Free more lattice atoms Damage continues

27、until all freed atoms stop One energetic ion can cause thousands of displacements of lattice atoms,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,43,Lattice Damage With One Ion,Heavy Ion,Single Crystal Silicon,Damaged Region,Light Ion,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.ht

28、m,44,Implantation Processes: Damage,Ion collides with lattice atoms and knock them out of lattice grid Implant area on substrate becomes amorphous structure,Before Implantation,After Implantation,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,45,Implantation Processes: Anneal,Dopant atom m

29、ust in single crystal structure and bond with four silicon atoms to be activated as donor (N-type) or acceptor (P-type) Thermal energy from high temperature helps amorphous atoms to recover single crystal structure.,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,46,Thermal Annealing,Dopant

30、 Atom,Lattice Atoms,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,47,Thermal Annealing,Dopant Atom,Lattice Atoms,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,48,Thermal Annealing,Dopant Atom,Lattice Atoms,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,49,Thermal Anne

31、aling,Dopant Atom,Lattice Atoms,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,50,Thermal Annealing,Dopant Atom,Lattice Atoms,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,51,Thermal Annealing,Dopant Atom,Lattice Atoms,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,52,

32、Thermal Annealing,Dopant Atom,Lattice Atoms,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,53,Thermal Annealing,Dopant Atoms,Lattice Atoms,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,54,Implantation Processes: Annealing,Before Annealing,After Annealing,Hong Xiao, Ph. D.,www2.a

33、ustin.cc.tx.us/HongXiao/Book.htm,55,Rapid Thermal Annealing (RTA),At high temperature, annealing out pace diffusion Rapid thermal process (RTP) is widely used for post-implantation anneal RTA is fast (less than a minute), better WTW uniformity, better thermal budget control, and minimized the dopant

34、 diffusion,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,56,RTP and Furnace Annealing,Poly Si,Si,RTP Annealing,Furnace Annealing,Poly Si,Si,Gate SiO2,Source/Drain,Gate,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,57,Question and Answer,Why cant the furnace temperature be rampe

35、d-up and cooled-down as quickly as RTP system ?,A furnace has very large thermal capacity, it needs very high heating power to ramp-up temperature rapidly. It is very difficult to ramp up temperature very fast without large temperature oscillation due to the temperature overshoot and undershoot .,Ho

36、ng Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,58,Ion Implantation: Hardware,Gas system Electrical system Vacuum system Ion beamline,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,59,Ion Implanter,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,60,Implantation Process,Gase

37、s and Vapors: P, B, BF3, PH3, and AsH3,Select Ion: B, P, As,Select Ion Energy,Select Beam Current,Next Step,Implanter,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,61,Ion Implanter,Gas Cabin,Ion Source,Vacuum Pump,Vacuum Pump,Electrical System,Electrical System,Analyzer Magnet,Beam Line,E

38、nd Analyzer,Wafers,Plasma Flooding System,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,62,Ion Implantation: Gas System,Special gas deliver system to handle hazardous gases Special training needed to change gases bottles Argon is used for purge and beam calibration,Hong Xiao, Ph. D.,www2.

39、austin.cc.tx.us/HongXiao/Book.htm,63,Ion Implantation: Electrical System,High voltage system Determine ion energy that controls junction depth High voltage system Determine ion energy that controls junction depth RF system Some ion sources use RF to generate ions,Hong Xiao, Ph. D.,www2.austin.cc.tx.

40、us/HongXiao/Book.htm,64,Ion Implantation: Vacuum System,Need high vacuum to accelerate ions and reduce collision MFP beamline length 10-5 to 10-7 Torr Turbo pump and Cryo pump Exhaust system,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,65,Ion Implantation: Control System,Ion energy, beam

41、 current, and ion species. Mechanical parts for loading and unloading Wafer movement to get uniform beam scan CPU board control boards Control boards collect data from the systems, send it to CPU board to process, CPU sends instructions back to the systems through the control board.,Hong Xiao, Ph. D

42、.,www2.austin.cc.tx.us/HongXiao/Book.htm,66,Ion Implantation: Beamline,Ion source Extraction electrode Analyzer magnet Post acceleration Plasma flooding system End analyzer,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,67,Ion Beam Line,Ion Source,Vacuum Pump,Vacuum Pump,Analyzer Magnet,Be

43、am Line,End Analyzer,Wafers,Plasma Flooding System,Post Acceleration Electrode,Extraction Electrode,Suppression Electrode,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,68,Hot tungsten filament emits thermal electron Electrons collide with source gas molecules to dissociate and ionize Ions

44、 are extracted out of source chamber and accelerated to the beamline RF and microwave power can also be used to ionize source gas,Ion implanter: Ion Source,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,69,Ion Source,Arc Power 120 V,Filament Power, 0-5V, up to 200A,+,-,Anti-cathode,Tungste

45、n Filament,Source Magnet,Source Gas or Vapor,Plasma,Magnetic Field Line,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,70,RF Ion Source,RF,RF Coils,Plasma,Dopant Gas,-,+,Extraction Electrode,Ion Beam,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,71,Microwave Ion Source,Magnetic

46、Field Line,Microwave,Magnetic Coils,ECR Plasma,Extraction Electrode,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,72,Ion Implantation: Extraction,Extraction electrode accelerates ions up to 50 keV High energy is required for analyzer magnet to select right ion species.,Hong Xiao, Ph. D.,w

47、ww2.austin.cc.tx.us/HongXiao/Book.htm,73,Extraction Assembly,Ion Beam,Ion Source,Plasma,Extraction Power, up to 60 kV,Suppression Power, up to 10 kV,+,+,Suppression Electrode,Extraction Electrode,Slit Extracting Ion Beam,Top View,Terminal Chassis,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.

48、htm,74,Ion Implantation: Analyzer Magnet,Gyro radius of charge particle in magnetic field relate with B-field and mass/charge ratio Used for isotope separation to get enriched U235 Only ions with right mass/charge ratio can go through the slit Purified the implanting ion beam,Hong Xiao, Ph. D.,www2.

49、austin.cc.tx.us/HongXiao/Book.htm,75,Analyzer,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,76,Ions in BF3 Plasma,IonsAtomic or molecule weight 10B10 11B11 10BF29 11BF30 F238 10BF248 11BF249,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,77,Question and Answer,Only 20% of boron

50、atoms are 10B 10B+ ion concentration is only 1/4 of 11B+ 10B+ beam current is 1/4 of 11B+ beam current Quadruple implantation time, lower throughput,10B+ is lighter and can penetrate deeper than 11B+, why dont use 10B+ in deep junction implantation?,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Bo

51、ok.htm,78,Ion Implantation: Post Acceleration,Increasing (sometimes decreasing) ion energy for ion to reach the required junction depth determined by the device Electrodes with high DC voltage Adjustable vertical vanes control beam current,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,79,

52、Ion Implantation: Plasma Flooding System,Ions cause wafer charging Wafer charging can cause non-uniform doping and arcing defects Elections are “flooding” into ion beam and neutralized the charge on the wafer Argon plasma generated by thermal electrons emit from hot tungsten filament,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,80,Post Acceleration,Ion Beam,Post Accel. Power, up to 60 kV,Suppression Power, up to 10 kV,+,+,Suppression Electrode,Acceleration Electrode,Terminal Chassis,Hong Xiao, Ph. D.,www2.austin.cc.tx.us/HongXiao/Book.htm,81,Ion