Bulk Material Micro-structuring and Surface Modifications

Transcription

1 Bulk Material Micro-structuring and Surface Modifications Micro-structuring mechanical electrical (EDM) chemical irradiation electrochemical Surface modification electrodeposition PVD/CVD Materials metals ceramics glass semiconductors polymers polymer coatings chemical SAMs

2 Principle of Optical Lithography mask UV-exposure of resist development result negative

3 SU-8 Microstructures to be Filled by Electroforming

4 Fabrication of Photonic Band Gap Structures by X-ray Lithography Generation of a fcc type lattice structure by triple inclined irradiation

5 3-D Microstructures in PMMA Made by LiGA - technique 100 µm 100 µm

6 Nd:YAG Laser Micromachining mixer inlay, stainless steel, d=0.2 mm slit width: 40 µm Applications: Cutting & Drilling: sublimation cutting, small kerf width material: metals, ceramics silicon, polymers (filled) small hole diameters (>10 µm, aspect ratio <100) Workstations: Laser: Nd:YAG (doubled) Wavelength: 1064 (532) nm Pulse length: 100 ns Pulse energy: 10 (1) mj, max. XYZ-table, 10 µm accuracy Scanner, feed rate up to m/s 1 mm mixer mould insert hard metal WC/Co inside marking, PMMA Laser Milling: rapid tooling/prototyping material: metals, ceramics silicon, polymers (filled) high resolution (down to 30 µm structure size) Laser Engraving: fast marking polymer inside marking high processing speed

7 Eximer Laser Micromachining Applications: cutting of PI foil 1 mm Polymer Machining: ablation (depth 5 µm to 1 mm, resolution <5 µm R a >0.2 µm, quasi 3D) fine cutting drilling (various hole shapes) EXITEC-Workstation: Laser: Excimer LPX110i Wavelength: 193 nm Pulse length: 17 ns Pulse energy: 200 mj (max.) XYZ-table, 1 µm accuracy Mask projection caterpillar mixer, PMMA prototype Ni mould insert hydrofocussing chip 0.3 mm Rapid Prototyping: microfluidic channels polymer bio chips microoptical structures Laser LIGA: mould insert fabrication material: Ni, Cu large number production (hot embossing, injection moulding)

8 Direct Laser Writing: Introduction

9 Direct Laser Writing: Experimental Setup PC Pumplaser Ti:Saphir (532 nm, 5 W) Oscillator (800 nm, 400 mw) Scanneroptics z-piezoactor xyz-table Microscope objective Autocorrelator Shutter Spectrometer

10 Interference Lithography: Working Principle If two (or more) coherent laser beams overlap in space, an interference pattern with distinct bright and dark regions is generated. Idea: Expose a photosensitive polymer layer (photoresist) with this pattern.

11 Interference Lithography: Simulation The pattern geometry is determined by the number of laser beams and their respective intensity, orientation, and polarization.

12 Direct Laser Writing: Wood-Pile Structures Resist: SU-8 Application: Photonic Crystals with complete band-gap

13 Direct Laser Writing: Results structure width [µm] 2,2 2,0 1,8 1,6 1,4 1,2 1,0 0,8 0,6 19 mw 12 mw 10 mw 7 mw structure height [nm] mw 12 mw 10 mw 7 mw 0, exposure time [ms] exposure time [ms] 1D Voxel 2D Lines 3D Bodies v

14 Interference Lithography: 2-D Structures The actual pattern obtained also depends on the properties of the photoresist material.

15 Electroforming of Nano-tip Arrays with Nickel AFM image HP 64174

16 Bulk Material Micro-structuring and Surface Modifications (V) Micro-structuring mechanical electrical (EDM) chemical irradiation electrochemical Surface modification electrodeposition PVD/CVD Materials metals ceramics glass semiconductors polymers polymer coatings chemical SAMs

17 Electrodeposition General Gold Copper Nickel Nickel-cobalt Nickel- iron Mold iserts Special types of nickel alloys Mold inserts from (ASE) silicon masters Resist Plating equipment

18 Principles of Micro Machining Steps Resist removing, separation Electroforming Microstructure Arbeitsmaske Mould insert or embossing tool Electroforming Resist removing, separation

19 Main Problems in Microelectroforming 1. Metal distribution Metal 4. Undercutting Resist Plating base 2. Adhesion 5. Internal stress 3. Particels and bubbles pressure tensile

20 Typical Defects Caused by Electroplating of fully metalized ASE-etched Si-surfaces Sputtered adhesion and seed layer Deposited nickel Electrolyte Electrolyte entrapment Aspect ratio 2:1 ASE-etched Si-master Deposited nickel Growing direction Sputtered adhesion and seed layer Aspect ratio 1:1 ASE-etched Si-master

21 Electrodeposition General Gold Copper Nickel Nickel-cobalt Nickel- iron Mold iserts Special types of nickel alloys Mold inserts from (ASE) silicon masters Resist Plating equipment

22 X-ray Mask Plating Process Si 3 N 4 Exposure A Si D Plating base Ti/Cu Development, gold plating B E AZ resist Si-etching C F 2µm Au-pattern

23 Electrodeposition of Gold: Working Conditions Gold electrolyte Modified commercial available gold sulfite electrolyte Gold content Sulfite as sodium sulfite Leveler ph - value Temperature Current density Anode material 8-12 g/l 40 g/l Arsenite / arsenate C A/dm² Ti/Pt mesh

24 Filter Mask Technology: Gold Electrodeposition in a Fountain Tower Cell Ah counter Carrier with mask substrate 0,2A 0,5V 0,5V Power supply Foutain tower cell Ti/Pt Anode 9.0 ph ph - electrode Additives Liquid volume control NaOH Tank 55 C Temperature control

25 High Leveling Gold Electrodeposition 100 µm 10 µm Thickness: 20 µm 5 µm

26 Mistakes in Electroplating of Gold - Leveler Concentration Too Low IMM,

27 Deep X-ray Lithography: Substrate Induced Defects Be + 2 H 2 O Be(OH) 2 + H 2 Au Be Au Formation of gas bubbles by dissolution of the Be-substrate during the electrodeposition process Be

28 Electroplating with AFM Tips: Gold Nanoelectrodes Electrode gap

29 Electrodeposition General Gold Copper Nickel Nickel-cobalt Nickel- iron Mold iserts Special types of nickel alloys Mold inserts from (ASE) silicon masters Resist Plating equipment

30 Nickel Sulfate Electrolyte: Working Conditions Nickel Boric acid Sulfaminic acid Sulfate Chloride Saccharin fluorinated wetting agent Anode material 100 g/l 40 g/l 275 g/l 14 g/l 5.0 g/l 20 mg 20 ml/l (2% solution) Sulfur depolarized nickel Anode reaction: Ni ±0 ===> Ni e Cathode reaction: Ni e ===> Ni ±0 2H + + 2e ===> H 2 Temperature 55 C ph - value 3.8 Current density 1-5 A/dm² Current efficiency ~ 99% Bath volume 75 l

31 Filter Ni-anode Nickel Electrodeposition: Flow Chart 1,5A 3,8V 0,2A 0,5V Ah counter Power supply Cell Wafer carrier 3.3 ph ph-electrode Additives Liquid level control Sulfamic acid Dummy plating Tank 55 C Temperature control

32 Fiber Alignment Device Deep UV-lithography electroforming with nickel Sacrificial layer technique

33 Negative Tone - Resist for Deep X-ray Lithography: Columns Replicated by Electroforming Columns: Diameter: 3 µm Height: 50 µm Material: Nickel Height: 45 µm Surface not polished 3802 RS

34 LIGA - Microstructures Made from Nickel: Oblique X-ray Irradiation

35 3-D Metallic Microstructures Technology: LiGA technique, multiple oblique irradiation with rotation of mask and substrate by angular steps of 120 Application: Photonic crystals Material: nickel

36 Modulus of elasticity [GPa] Young s Modulus of Nickel Microstructures Dimension of the test piece: 2800 µm * 100 µm * 400 µm Annealing temperature [ C] ( S. Abel; PhD thesis, unpublished results )

37 Hardness [HV] Hardness of Ni-microstructures vs. Annealing Temperature 500 Electrolyte: Nickelsulfamate Wetting agent: FT 248 Current density: 1 A/dm² Complete recrystallisation Annealing temperature [ C]

38 Electrodeposition General Gold Copper Nickel Nickel-cobalt Nickel- iron Mold iserts Special types of nickel alloys Mold inserts from (ASE) silicon masters Resist Plating equipment

39 Nickel-Cobalt Sulfate Electrolyte: Working Conditions Nickel Cobalt Boric acid Sulfamic acid Sulfate Chloride Saccharin fluoriertes Wetting agent 90 g/l 2.8 g/l 40 g/l 200 g/l 15 g/l 1.8 g/l 20 mg 20 ml/l (2% solution Anode reactions: Ni ±0 ===> Ni e Co ±0 ===> Co e Cathode reactions: Ni e ===> Ni ±0 Co e ===> Co ±0 Temperature 55 C ph - value 4.0 Current density 1-5 A/dm 2 Current efficiency ~ 97% Bath volume 75 l 2H + + 2e ===> H 2

40 Nickel-cobalt Sulfamate Electrolyte: Mass Balance Cell Regeneration Cathode rections: Ni e Ni 0 Co e Co ±0 2H + + 2e H 2 Ni e Ni 0 Co e Co ±0 2H + + 2e H 2 j = j Ni + j Co + j H j Ni + j Co + j H Anode reactions: Ni ±0 Ni e Co ±0 Co e J Ni = j Ni(Cell) + j Ni(Regeneration) j Co = j Co(Cell) + j Co(Regeneration)

41 Co-anode Filter Ni-anode Ni-Co Alloy Electrodeposition: Flow Chart 1,5A 3,8V 0,2A 0,5V Ah counter Carrier with wafer Power supply Cell VIS-photometer 3.3 ph ph-electrode Additives Liquid level control Sulfamic acid Tank 55 C Temperatur control Regeneration

42 Cobalt content in the deposit [%] Electroplating of Ni-Co Microstructures Cobalt content in the deposit versus cobalt concentration in the electrolyte 30 ph 4.0 T 55 C Cobalt content in the electrolyte [ g/l ] Nickel Sodium sulfamate Sodium sulfate Chloride 90 g/l 40 g/l 15 g/l 1.8 g/l

43 Hardness (HV 5) Electroplating of Ni-Co Microstructures Electrodeposition of Ni-Co micro-structures: micro-hardness versus cobalt content in the deposit 340 ph 4.0 T 55 C 320 Nickel 90 g/l 300 Sodium sulfamate Sodium sulfate 40 g/l 15 g/l Cobalt content in the deposit [ % ] Chloride 1.8 g/l

44 Electroforming of Mould Inserts Material: Ni-Co alloy

45 Electrodeposition of Ni-Co (73/27) Alloy Micro gears manufactured by LIGA-technology

46 Electrodeposition General Gold Copper Nickel Nickel-cobalt Nickel- iron Mold iserts Special types of nickel alloys Mold inserts from (ASE) silicon masters Resist Plating equipment

47 Nickel-Iron Alloy Electrodeposition: Working Conditions Nickel Iron Boric acid Sulfate Complexing agent Chloride Saccharin Tenside 50 g/l 1-9 g/l 45 g/l 80 g/l 15 g/l 18 g/l 20 mg 5 ml/l (2% Lösung) Anode reaction: Ni ±0 ===> Ni e Fe ±0 ===> Fe e Fe 2+ ===> Fe e Cathode reaction: Ni e ===> Ni ±0 Fe e ===> Fe ±0 Temperature 55 C ph - value 3.5 Current density 1-5 A/dm² Current efficiency ~ 98% Volume 50 l 2H + + 2e ===> H 2 Side reaction: Fe 2+ + Oxygen in air ===> Fe 3+ 2Fe 3+ + Fe ±0 ===> 3Fe 2+

48 Ni-anode Filter Ni-anode Fe-anode Nickel-Iron Alloy Electrodeposition: Flow Chart 1,5A 3,8V 0,2A 0,5V 0,5V PC Ah -counter PC Power supply VIS-photometer Cell Potentiostat 3.3 ph ph-electrode Additives Liquid level control Sulfuric-acid Dummy plating Tank 55 C Temperature control

49 Nickel-iron Sulfamate Electrolyte: Mass Balance Cell Regeneration cell Cathodic reactions: Ni e Ni 0 Fe e Fe ±0 2H + + 2e H 2 Ni e Ni 0 Fe e Fe ±0 2H + + 2e H 2 j = j Ni + j Fe + j H j Ni + j Fe + j H Anodic reactions Ni ±0 Ni e Ni ±0 Ni e Fe ±0 Fe e Side reactions: Fe 2+ + oxygen in air Fe 3+ 2Fe 2+ + Fe ±0 3Fe 2+

50 Saturation magnetization [ T ] Comparison of Nickel and Nickel-Iron Microstructures: Hysteresis Curves 1,5 1,0 0,5 0-0,5-1,0 Nickel Ni-Fe (50:50) -1, Magnetic field H [ A/m ] SA 3004

51 Material For Leaf-Springs; Electroplated Ni-Fe (90/10) Alloy

52 Breaking load cycle Endurance Strength of Ni-Fe Alloy Microstructures ,000,000 cycles Iron content [%]

53 Micro Harmonic Drive : Flex Spline - Gear ratio Torque 15 mnm - Up to rpm 300 µm

54 Electrodeposition Gold Copper Nickel Nickel-cobalt Nickel- iron Mold iserts Special types of nickel alloys Mold inserts from (ASE) silicon masters Resist Plating equipment

55 Nickel Mold Insert for Lab-On-A-Chip Fabrication Delay loop Reservoirs 2 Reservoirs 1 Separation channel Reactand dosing IMM, Iso

56 Mold Insert for Micro-optical Structures LIGA - technique Material: Nickel Dimensions: 25mm x 25mm Fiber Grooves for 125 µm singlemodule fibers, microcuvettes and lens systems for beam shaping

57 Polymer Chip Design and Fabrication Fabrication of master by Advanced Silicon Etching (ASE) Electroforming of mold insert by using NiFe electrolyte Plastic chip manufacturing 25 reaction chambers supplied by microfluidic channels Reaction volume 20 nl Surface functionalization of microchannels via wet chemical process Liquid transport by combination of capillary forces and membrane actuators

58 Ultraprecision Hot Embossing Resist master Glass base Metallisation Electrolytic reinforcement Embossing tool Minimum feature size: <3nm Reproducibility: <1nm PC-foil Sensor component IMM,