ATI Cleanroom facilities Contact: T.E. Sale, 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 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

ATI Cleanroom facilities Contact: T.E. Sale, Advanced Technology Institute, School of Electronics and Physical Sciences, University of Surrey, Guildford, GU2 7XH Rapid anneal to 1100°C Separate III-V, Si and FeSi, glassware. Computer controlled Soon to be adapted to run on several gases (O 2, N 2, H 2 :N 2 & Ar) Thermal processing Leybold E-beam Metal contact dedicated system Good for hard & refractory metals Balzers E-beam Much larger system – better uniformity but uses more source material Will become dedicated dielectric coating system. Coatings for mirrors, windows etc E-beam Evaporators Heat material to be evaporated in crucible by bombarding with high current electron beam Particularly good for high melting point materials. Can perform in reactive atmosphere, e.g. Oxygen, to control composition 2 systems : dielectric multilayers metals Process Products 18 lamp RTA Tube furnace Slowish (1-2 mins) anneal to 650°C Manual process control N 2, H 2 :N 2 User provides own tube – can be used for wide range of things without contamination issues Small samples (15x20mm 2 ) 8 lamp RTA Rapid anneal to 1100°C Computer controlled Small samples Potential to have tubes for different materials III-V selective oxidation Used for converting Al rich alloys to insulating Al 2 O 3 for buried current and optical confinement Strip lamps allow rapid anneal to 600°C Low pressure and high pressure carrier gas modes of operation Thermal Evaporators Heat material to be evaporated by passing current through Ni or Mo coil or boat 5 systems : 1. p metals 2. n metals 3. organics 4. Al only (for Si) 5. General system Evporative deposition 4 Chemical stations: 2 general use 1 Hydrofluoric acid use 1 Photolithography 3 additional fume cupboards elsewhere in ATI Wet chemical processes are used extensively in most device processes and material characterization activities. This includes etching, cleaning and surface treatments. The wide range of process technologies supported in the ATI creates require significant flexibility. The chemical stations are among the most critical areas for cleanliness. Hydrofluoric Acid (HF) HF is used mainly to remove oxide layers and to prepare surfaces. It is very dangerous: delayed burns & demineralises bones. Dedicated area – allows other lab users to keep well clear. Wet chemical processing Supporting the cleanroom Service corridors behind the equipment contain pumps, compressors etc. toxic extracts and other services Gases are supplied from external bottles in a cage. Nitrogen from liquid boiloff A sophisticated alarm system monitors the cleanroom and service areas for leaks of toxic and flammable gases. Some of the gases are toxic in the parts per billion range Microscopes Various optical microscopes for simple inspection Image capture and measurement systems Various test systems exist in the cleanroom and other labs. In the cleanroom, they are only intended for quick mid process tests - generally better facilities exist elsewhere in the ATI for more detailed measurements. Plas-mos ellipsometer Single wavelength (HeNe) ellipsometer For thickness measurement of transmissive films More advanced spectroscopic system available elsewhere within SEPS Wire Bonding Gold wire ball-wedge bonder Installed with 15μm gold wire For wiring devices into packages Optical and test systems 2/2 Chemical storage Probe stations x2 (manual and auto) - manual prober operation. 4 point probe - operational Talystep surface profiler (in prep lab). Also Dektak 3 in LAE lab.