What is optical lithography? The optical system Production process Future and limits of optical lithography References. Optical lithography

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1 Optical lithography Robin Nagel TUM 12. Januar 2009 Robin Nagel (TUM) Optical lithography 12. Januar / 22

2 1 What is optical lithography? 1 The optical system 1 Production process 1 Future and limits of optical lithography 1 References Robin Nagel (TUM) Optical lithography 12. Januar / 22

3 What is optical lithography? Lithography (from the Greek - lithos: stone + grapho: to write ) optical lithography is a process used to selectively remove parts of a thin film. Until now, it is the only way for industrial mass production of computer chips Robin Nagel (TUM) Optical lithography 12. Januar / 22

4 The optical system Robin Nagel (TUM) Optical lithography 12. Januar / 22

5 Mask making process Exposure Develop Etch Robin Nagel (TUM) Optical lithography 12. Januar / 22

6 What is optical lithography? The optical system Production process Future and limits of optical lithography References Photoresist The photoresist (DiazoNaphtoQuinon-(DNQ)Sulfonat) reacts under the influence of the light to an Inden-carboxylic acid The carboxylic acid has in orders of magnitude a higher solubility The bonding of the SO2 R group defines the absorbed wavelength Robin Nagel (TUM) Optical lithography 12. Januar / 22

7 What is optical lithography? The optical system Production process Future and limits of optical lithography References Defects Particles in the photoresist (dust,old photoresist) Bubbles Rough substrate Tear-off Robin Nagel (TUM) Optical lithography 12. Januar / 22

8 Kinds of photoresist Robin Nagel (TUM) Optical lithography 12. Januar / 22

9 Oxidation and exposure Lightsources can be: Mercury lamps with a wavelength of 365nm state-of-the-art light sources are Argon Fluoride (ArF) Excimer lasers with a wavelength of 193nm Robin Nagel (TUM) Optical lithography 12. Januar / 22

10 Etch process Robin Nagel (TUM) Optical lithography 12. Januar / 22

11 Diffusion and implant Robin Nagel (TUM) Optical lithography 12. Januar / 22

12 Deposition Robin Nagel (TUM) Optical lithography 12. Januar / 22

13 Oxidation Robin Nagel (TUM) Optical lithography 12. Januar / 22

14 Interconnects Robin Nagel (TUM) Optical lithography 12. Januar / 22

15 Metallization Robin Nagel (TUM) Optical lithography 12. Januar / 22

16 Chemical mechanical planarization Robin Nagel (TUM) Optical lithography 12. Januar / 22

17 Interconnects and layers Robin Nagel (TUM) Optical lithography 12. Januar / 22

18 Future and limits of optical lithography Rayleigh equation: W = k λ - k= resolution factor - λ= wavelengh NA - NA= Numerical aperture For example: λ=193nm, NA=0.93 and k= nm W = = 52nm 0.93 Use of Extrem UV lights (13nm) or X-Ray (0.5nm) Use of new materials and techniques (such as immersion lithography) Robin Nagel (TUM) Optical lithography 12. Januar / 22

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22 References 1 lecture nanoelectronics by Prof. Lugli at the Tum 2 Intel, The High-k Solution, Paolo A. Gargini, Silicon nanoelectronics and beyond, Gordon E. Moore, Cramming more components onto integrated circuits, Reed Business Information, 32 nm Marked by Litho, Daniel Bratton, Da Yang, Junyan Dai and Christopher K. Ober, Recent progress in high resolution lithography, Yong Chen, Anne Pepin, Nanofabrication:Conventional and nonconventional methods, icknowledge, Technology backgrounder: Immersion Lithography, Microchemicals, Lithografie, 2007 Robin Nagel (TUM) Optical lithography 12. Januar / 22