Xing Sheng, EE@Tsinghua

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Xing Sheng盛兴

Department of Electronic EngineeringTsinghua University

xingsheng@tsinghua.edu.cn

Film DepositionPart VI: Wet Process

Principles of Micro- and Nanofabrication for Electronic and Photonic Devices

Xing Sheng, EE@Tsinghua

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Film Deposition

PVD: Physical Vapor DepositionCVD: Chemical Vapor Deposition 'dry' process

Xing Sheng, EE@Tsinghua

Solution based Deposition

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'wet' process

Xing Sheng, EE@Tsinghua

Copper - electroplating

Silver - electroless plating

Liquid Phase Epitaxy (LPE)

Spin-on glass

Organics / Quantum Dots

Examples

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Xing Sheng, EE@Tsinghua

Interconnects for CMOS

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copper replaces aluminum below 130 nm

Q: why?

Xing Sheng, EE@Tsinghua

Interconnects for CMOS

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Aluminum

conductive reliable and stable easy deposition easy etching low diffusivity in Si

and SiO2 good adhesion with

Si and SiO2 low cost ...

Xing Sheng, EE@Tsinghua

Interconnects for CMOS

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Copper

more conductive

Aluminum

conductive reliable and stable easy deposition easy etching low diffusivity in Si

and SiO2 good adhesion with

Si and SiO2 low cost ...

Copper wins!

vs.

Xing Sheng, EE@Tsinghua

Interconnects for CMOS

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Reduces RC circuit delay, reduce power consumption

- Al is cheap and easy to deposit- Ag and Au are expensive- Cu is cheap and conductive- Carbon (graphene) is the best

what is next, Ag or Carbon?

above 130 nm

below 130 nm 60Copper (Cu)

43Gold (Au)

38Aluminum (Al)

63Silver (Ag)

100Graphene (C)

Conductivity (106 S/m)

Materials

RIP

RCt2~

~

Xing Sheng, EE@Tsinghua

Step Coverage

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CVD is preferred for via fillingAl, W can be deposited by CVDbut CVD Cu is very difficult ...

Xing Sheng, EE@Tsinghua

Copper Electroplating (电镀)

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Printed Circuit Board

五毛

Video

Xing Sheng, EE@Tsinghua

Copper Electroplating (电镀)

11F. Wang, et al., Sci. Rep. 7, 46639 (2017)

Cu

Xing Sheng, EE@Tsinghua

Damascene Process for Cu

12P. C. Andricacos, et al., IBM J. Res. Develop. 42, 567 (1998)

Cu

SiO2

ancient art work

Xing Sheng, EE@Tsinghua

Damascene Process for Cu

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Electroplating + CMPdirtiest process for the most advanced IC

Xing Sheng, EE@Tsinghua

Electroless Plating

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silver mirror reaction

Xing Sheng, EE@Tsinghua

Liquid Phase Epitaxy (LPE) 2Ga (l) + 2AsCl3 (l) = 2GaAs (s) + 3Cl2 (g)

LPE - Liquid Phase Epitaxy

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Xing Sheng, EE@Tsinghua

Spin-on Glass (SOG)

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form SiO2 from solvent

Xing Sheng, EE@Tsinghua

Porous SiO2 for Low Dielectric

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SiO2 = 3.9

air = 1.0

prepared by spin-on methods

Xing Sheng, EE@Tsinghua

Organic Solar Cells

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Xing Sheng, EE@Tsinghua

OLEDs

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Xing Sheng, EE@Tsinghua

Fully Solution Processed Devices

20J. Choi, et al., Science 352, 205 (2016)

Xing Sheng, EE@Tsinghua

Colloidal Quantum Dots

21J. Bao and M. G. Bawendi, Nature 523, 67 (2015)

Xing Sheng, EE@Tsinghua

Perovskites (钙钛矿)

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deposit by spin coating or evaporation

> 20 Nature/Science papers every year

solar cells LEDs