Trinity College Dublin

Facilities

The MTL is fully equipped to carry out IC processing: chemical etching, photolithography, oxidation, diffusion, and metallisation. Our facility comprises a 300m², class 7 (class 10,000) clean room, a 60m², electrical testing and characterisation laboratory and a 30m², class 5 (class 100) clean room for research photolithography. Details of our main processing capabilities are outlined below.

Our characterisation suite houses various state-of-the-art characterisation tools including a Renishaw 1000 micro-Raman system, a Rudolf LF 04 ellipsometer, and there is access to a Digilab 6000 FTIR spectrometer with IR microscope. Miscellaneous equipment includes a Taylor-Hobson profilometer, 4 point-probe and I-V and C-V characterisation systems.

Processing Equipment
	- Wafer Etching - Photolithography - Thermal Processing - Electrical Characterisation - Ion Etching - DI Water Plant
Characterisation Equipment

Processing Equipment

Wafer Etching

Wafer Cleaning Bench

PLADE chemical etch acid/solvent wet bench. Included on this bench are dedicated baths for:
1:1 solutions of hydrogen peroxide (H2O2) and sulphuric acid (H2SO4) to oxidize surface layers of silicon.
10:1 solutions of H2O:HF for oxide stripping.
7:1 BOE (Buffered Oxide Etch) for silicon dioxide etch.

Spin Rinse Dryers

Semitool spin rinse dryers are used for washing and spin drying silicon wafers. De-ionized water is sprayed over the wafers, which are then spun dry in a cassette at about 2500 rpm. Heated dry nitrogen is also blown over the wafers to break up droplets.

Photolithography

Cobilt CA-800 Mask Aligners

Precisely positions a photomask into correct registration with a photoresist coated wafer and performs a uniformly illuminated exposure through the mask with a filtered high-pressure mercury arc lamp.

This is a contact aligner, as the photomask and the substrate wafer are brought into physical contact during the exposure. This is the primary instrument for performing photolithography pattern transfer.

With a tuned-up photoresist process, space and trace patterns of 2 microns pitch can be printed. Uses a 200 Watt Hg short arc arc lamp exposure source.

Photoresist Spin Coaters

Electronic Micro Systems Ltd. Model 4000 photo resist spinners. Precisely spins a circular substrate wafer to uniformly spread out a coating of photoresist.

The substrate is held by a vacuum chuck while a motor spins the substrate and chuck at speeds of between 100 and 6500 rpm with an operating cycle of 0 to 650 seconds.

Edwards E306 Metal Deposition

Evaporation system for metal depositions of aluminium, gold and other metals. Consists of an 8" diameter sample mounting area. High vacuum achieved with a liquid N2 baffled diffusion pump.

Thermal Processing

Furnace Stacks

Our furnace stacks are served by fully automated DSE-Philips furnace loaders.

Diffusion

This equipment consists of a horizontal quartz furnace for high temperature processing of silicon wafers and other substrates. By varying the temperature and gas composition flowing to the tube, solid source doping and diffusion is performed with the system.

Currently used for solid source boron diffusion. (Figure below shows n-type silicon wafers being placed either side of boron nitride disks (white), just prior to diffusion).

Field Oxidation

This equipment consists of a horizontal quartz furnace tube for high temperature wet oxidation of silicon wafers and other substrates.

By using a bubbler system (shown below) N2 (carrier gas) is bubbled through a hot water bath at 98°C and thermally decomposed steam replaces O2 as the oxidizing gas.

Gate Oxidation

We currently have a dedicated quartz furnace tube for trichloroethylene (TCE) assisted gate oxide formation. During this process, a little TCE is carried down the tube by a slow bleed of N2.

Rapid Thermal Processing

The rapid thermal processor is a AG Associates heat pulse 610 system. This system uses a high intensity visible radiation to heat a single wafer for short periods of between 1 to 300 seconds. in a temperature range of 400 to 1150ºC.

The unit can be used in the following areas; ion implantation, polysilicon annealing, oxide reflow, silicide formation, contact alloying. GAA’s processing, oxidation and nitridation.

Electrical Characterisation

Probe Station

The Microanalytical probe system model 7000-LTE (Micromanipulator Co. Inc.) is used to apply electrical contact to test small geometric patterns. Tungsten tips can probe feature sizes up to 25 microns. This machine can probe up to 4” wafers or individual die.

Four Point Probe

The Alessi Industries four point probe can measure the resistive properties of semiconductor substrates and resistive films. The probes are stationary and the wafer is moved into the probe heads with constant force.

Ion Etching

Reactive Ion Etcher (under installation)

The Plasma Therm Inc. (SCR Series VII) system is a dry etch system. It uses an RF plasma with SF6, CHF3, and O2 gases to etch Silicon, SiO2, Si3N4, and polyimide. It can also be used to strip photoresist.

Ion Mill Beam

This Millatron Commonwealth Scientific system employs a COPRA (Controlled Plasma ReActor) filamentless RF driven low pressure plasma beam source to perform ion milling or ion beam assisted deposition.

DI Water Plant

Vivendi DI Water Plant

This facility supplies ultra-high purity de-ionized water to the wet benches and other equipment in the laboratory areas. It is a continuous closed-loop re-circulation system that produces water of resistivity 17 megaohm/cm3 with particulates filtered to 0.2mm.

Characterisation Equipment

Renishaw 1000 Micro-Raman System

Contains a spectrometer, triple mode (514, 488 and 457 nm) Ar+ ion laser, CCD detector and Leica microscope with 5x, 20x, 50x and 100x objective lenses.

The system is equipped with XYZ motorized positional stage that allows Raman line and area mapping experiments with a step of 0.1 mm.

The Micro-Raman system can be used for measurements of Raman and photoluminescence spectra of a wide range of materials. In particular it can be used for composition, stress, and strain analysis in different silicon structures including patterned Si wafers.

Infrared Microscope UMA 500 in Conjunction with Digilab 6000 Time-Resolved FTIR Spectrometer

This spectrometer allows the registration of spectra in a wide spectral range 50-15000 cm-1. It is equipped with numerous detectors, DTGs and two MCTs (wide-band and narrow-band) cooled by liquid nitrogen.

Taylor-Hobson (Talysurf 10) Profilometer

This equipment measures surface profiles by scanning a mechanical stylus across the sample. The profilometer can be used to measure etch depths, deposited film thickness and surface roughness.

Rudolph Focus (FE-IV) Ellipsometer (Donated by Intel (Ireland) Ltd.)

The ellipsometer is a non-destructive optical tool which analyzes polarized light reflected from thin films on the surface of substrates to determine the film thickness and refractive index of the film material.

Leica Ergoplan Microscope (Donated by Intel (Ireland) Ltd.)

Used for monitoring of process steps and defect analysis. Also at our disposal is a Nikon Optiphot optical microscope plus CCD colour camera.

If you would like further information on our laboratory please contact the Laboratory Manager, Dr. Aran Rafferty.