ATI Cleanroom facilities ATI Cleanroom facilities Contact: T.E. Sale, [email protected] Advanced Technology Institute, School of Electronics and Physical Sciences, University of Surrey, Guildford, GU2 7XH • Class 1000 with class 100 areas for lithography and sensitive work. • 95 current users, mainly from ATI but some from other schools and commercial. •Around 30 major items of process equipment. • Many smaller systems and manual processes Cleanroom class •Main area - Class 1000 (1000 particles >0.5μm per cu ft.) • Photolith area and adjoining room – class 100 • Standard room ~1,000,000. • A modern CMOS fab is class 0.1-1 • Our cleanroom is more than adequate for prototyping and development of discrete devices or those with small scale integration. Material system compatibility Cleanroom devised to cater for all the research areas of the ATI, i.e. the following materials technologies • Si: electronics, waveguides & light emitters • III-Vs (GaAs, InP, GaN based): electronics & opto • C-materials (nanotubes, DLC) • Things on glass • Organics & biomaterials • Nanomaterials Processes include • Plasma etching • Plasma deposition • Metal deposition • Wet Processing • Thermal processing • Excite plasma of Ar, N or O – ions bombard target material causing molecules to “sputter” off onto your sample • Large source area – conformal coating possible. • Good surface adhesion • Deposition material needs to be prepared as target. • Can be used for metals and insulators JLS sputterer • 3 x 4” magnetrons – space for 4 th . Co-sputtering •DC & RF sources – co sputtering & independent substrate bias. • Substrate heating to 600°C • Load locked – fast turn around. Nordiko 2000 sputterer • 4 x 8” magnetrons – layer at a time, expensive for precious metals (£20k-£40k for Au) • RF & DC sources. • Plasma diagnostics – optical emission and mass analyser. Sputtering Inductively Coupled Plasma (ICP) Etching • Plasma excited by inductive coils. Separate RF supply accelerates plasma to sample • Independent control of plasma density and energy – very high density plasma. •Good for hard materials e.g. GaN & SiC or for very deep or high aspect ratio features. STS Multiplex ICP etcher • Fully commissioned. • Wide variety of gases, can run O 2 , CF 4, , C 4 F 8 SF 6 , H 2 , CH 4 , Ar now. Cl 2 , SiCl 4 , BCl 3 later • Load locked, 6” wafers or smaller on carrier. Reactive Ion Etching (RIE) • RF applied to parallel plates to excite plasma in reactive gas injected into chamber • Two systems in cleanroom • III-V system – Currently runs SiCl4, Ar & O2,, undergoing upgrade to include CH4:H2 and CF4. • Si based system – to run CF4, SF6 & O2 for Si & SiO2 etch. Dry Etching Barrel Ashing •Generally used with oxygen plasma to remove organics, e.g. burnt on resists & grease. Ion Milling • Broad beam of Ar ions used to remove material • Use at Surrey has been mainly creating windows in metal contacts – post process modification Overview Class 100 area (Yellow Room) for patterning resists for lift-off or etch definition Contains •2 optical mask aligner systems • Spinners • Hotplates – fixed temperatures. • Ovens Karl Suss MJB3 aligner • Basic workhorse system • Small samples and wafers up to 2” •Quick and easy to use • Resolution limited (>1μm or so) due to optics Quintel UL7000 aligner • Many advanced features • Small samples, squares and wafers to 6”. Potential for 8” with additional tooling. •Soft, Hard, Vacuum & proximity contact. • 3 front to back alignment modes • Should do 0.5μm resolution – dependant on user & resist etc. Photolithography • Similar set-up to RIE, but RF applied to other electrode. • e.g. SiH 4 & N 2 O decompose to create SiO 2 • Three systems in cleanroom General- For deposition of Si, SiOxNy and B, P, Ge and F doped layers for conductive or silica waveguides Si based system – For deposition of SiOxNy on Si – where cross contamination may be an issue. Diamond like carbon (DLC) system – actually another RIE Trikon Delta system • Load locked system with sophisticated computer control • Fitted with dopant gases Plasma Enhanced Chemical Vapour Deposition (PECVD) 1/2