Cleanroom Facilities: Experience from an usernanocenter.eng.wayne.edu/Nano workshop...Cleanroom...

WAYNE STATE UNIVERSITY Cheng Cleanroom 8/2

Cleanroom Facilities:

Experience from an user

Mark Ming-Cheng Cheng

Electrical and Computer EngineeringWayne State University

Detroit MI [email protected]

Thin Film Deposition

Microfabrication is the term that describes processes of fabrication of

miniature structures, of mironmeter sizes and smaller. Historically the earliest

microfabrication processes were used for integrated circuit fabrication, also

known as “semiconductor manufacturing”, ” microelectronic fabrication”, ”VLSI

technology”.

Micro/Nano Fabrication

WAYNE STATE UNIVERSITY Cheng Cleanroom

2 cores; Introduced 20061.8 ~3GHz

291 millions transistorsDie size 111mm2; 65W

65nm

In the last two decades, microfabrication has been used in many research fields, including

* Micro Electromechanical System (MEMS)

* RF MEMS (resonators, filters, switches, phase shifters)

* Microfluidics/ Lab-on-Chip

* Bio MEMS

* Solar cells

* Flat panel display

* NEMS

Thin Film DepositionMicro/Nano Fabrication


Thin Film DepositionEnabling Technology in iPhone


Microphone

Accelerometer

GPU (graphic processor) 45nm

Thin Film DepositionHow to Make Sandwiches?


METHOD AND APPARATUS FOR MAKING A SANDWICHInternational Publication Number WO 2006/068865 AW Section (54)

Add breadCut bread

Cut vegetablesPlace vegetables

…

How to Make Devices?


/etching

Deposition ModulePhotolightography Module (Pattern Transfer)

Etching Module

pMOS

Materials


Semiconductor Insulator Metal

(Si, C, SiC, GaAs ) (SiO2, Si3N4,glass, (Au, Pt, Al, Cr, Ti, Ni..)

polymer, ceramics)

Thin Film Deposition (overview)


I. Furnace (Few hundred~11000C, atmosphere): SiO2, P++

II. Low Pressure Chemical Vapor Deposition System (LPCVD):

polycrystalline Si, amorphous SiO2

III. Plasma Enhanced Chemical Vapor Deposition System (PECVD):amorphous Si, nitride, SiO2

IV. E-beam Evaporator: metals (Al, Cr, Cu, Au, Ni, Pt, Ti, Mo),Si, Ge

V. Sputtering: Target Ti, Al, Al with 1%Si, 1%Cu), Mo, Au, Pt, Ta, Ni, Co, Cr,

Si, Pyrex, ITO Gas Ar, N2, O2

Furnace


Few hundred~11000C, atmosphere Thermal oxide (dry): excellent electrical property,

10nm~300nm

Thermal oxide (wet): 100nm~1-2µm

Boron diffusion (BN source):boron doping, P++

etching stop

Metal annealing (N2 gas)

22OSOS

ii→+

Low Pressure Chemical Vapor Deposition


I . Polysilicon

Pressure 50-150Pa

Deposition rate 100~2000A/min, 600~6500C

Polycrystalline Si ~2µm

Polysilicon is widely used as metal gate in CMOS as

well as structural layers in MEMS.

II. Low temperature oxide (LTO)

SiH4

600o

C → Si + 2H

2

22

400

242HSiOOSiH

Co

+ →+

Plasma Enhanced Chemical Vapor Deposition


Reaction Gas SiH4, NH3, N2O

Power max 400W

Temperature 25~3000C

Deposited Materials

α-Si : gas SiH4

SixNy: gas SiH4, NH3

SixOy: gas SiH4, N2O

SiOxNy: gas SiH4, NH3, N2O

Typically used for depositing passivation layers

Deposition rate 4000A/min (deepening on power and temp)

E-beam evaporator x2


Two evaporators: BJD, FC

Dual Guns with 4 pockets

Substrate heating ~2500C

Available sources: metals (Al, Cr, Cu, Au,

Ni, Pt, Ti, Mo),Si, Ge

* There will be additional material fee for

Au and Pt

wafers


Photographic Process

Photolithography


Contact Aligner

Provide alignment in x,y,z directions

Exposure resolution ~0.8µm

“ Print with the light”

Light sensitive film

Cr mask in contact with wafers

Photolithography (steps)


I. Spin-coating PR II. Soft Bake

III. Alignment/Exposure

IV. Developer

(Selectively remove PR)

SU-8


SU-8 ( from Microchem)A viscos polymer that can be spin-

coated and produce microstructures

Negative PhotoresistThickness 1~300µm

Microstructures with high aspect ratio

20

Thin Film Etching (Overview)


I. Wet etching, isotropic etching: Au etch, Al etch, Cr etch, Ni etch

II. Wet etching, anisotropic etching (bulk micromachining): TMAH etch

III. Metal Lift-off

VI. RCA clean: wafer cleaning

V. Dry etching, anisotropic etching

LAM etcher ( polysilicon, nitride, SiO2)DRIE (silicon); high aspect ratio silicon microstructures.

VI . Dry etching, isotropic etching

Drytech (PR, PDMS)

XeF2 (silicon)

Wet etching


I. Isotropic

II. Anisotropic

Substrate orientation

Crystal Plane

Orientation

TMAH, KOH

SiHNO3:HF:CH3COOH

(110) Si

(111) Si


DRIE (Deep Reactive Ion Etching)

Bosch Process

Silicon etch rate 0.6-0.7µm/loop;

3-4 µm/min

Mask: PR, SiO2, Al

Drytech


Dry Isotropic etching of polymers (Oxygen

plasma, Asher)

Reaction gas: O2, Ar, CF4

Power Max 300W

Oxygen plasma is widely used for

(1)Substrate cleaning

(2)Removal of PR(3)Removal of polymer/organic materials

(4)PDMS bonding

XeF2


Xenon Difluoride (XeF2) Etching • Home-made equipment (Cheng, Xu)

• Dry, Isotropic etching of Si

2XeF2 + Si →2Xe + SiF4

• High selectivity for Al, SiO2, Si3N4,PR,PSG

• Typical etch rates of 1 to 3 µm/min

• XeF2 reacts with water (or vapor) to form HF

Other Capabilities


Packaging

Characterization

Wafer Bonder Dicing Saw Wire Bonder

Surface Profiler Interferometer

On-Going Projects


Dr Yong Xu (Joined Wayne State 2002)

NSF ECCS A novel 3-dimensional neural probe technology combining electrical and chemical

interfaces (PI)

NSF CMMI Collaborative Research: Fish-Inspired Ultra-Sensitive Infrasound Sensor for Critical

Infrastructure Monitoring and Geo-Hazards Early Warning (PI)

NSF ECCS CAREER: Wearable accelerometers for continuous respiratory sound monitoring (PI)

NIH R21 Development of a neurotransmitter based epiretinal prosthesis (co-PI)

NSF CBET Neurophysiologically-based computational platform for the characterization and

optimization of retinal prosthetic stimulation (Co-PI)

Dr Amar Basu (Joined Wayne State 2008)

NSF CBET Microfrationation in Droplets (FD) - Linking Proteomic Separations to High

Throughput Functional Screening (PI)

Dr Mark Ming-Cheng Cheng (Joined Wayne State 2008)

NSF CBET CAREER: A Robust, Chronic Neural Prosthesis Using High-Capacity Graphene

Electrodes and Biodegradable Silicon Support (PI)

Resources


Related CoursesECE 5575 Introduction to Micro and Nano Mechanical Systems

ECE 6570 Smart Sensor Technology I: Design

ECE 7570 Smart Sensor Technology II: Characterization and Fabrication

Schedule

https://my.ilabsolutions.com/service_center/show_external/2964/nan

o-fabrication-core-facility

Nanotechnology


Nanotechnology deals with structures sized between 1 to 100 nanometers in

at least one dimension, and involves developing materials or devices

possessing at least one dimension within that size.

Cleanroom Facilities: Experience from an usernanocenter.eng.wayne.edu/Nano workshop...Cleanroom...

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