This thinfilm can be a metal like aluminium or chromium and nonconductive oxides like SiO2 or a transparent conductor like Indium Tin Oxide (ITO). Even thin organic coatings are possible like evaporation of O-led materials or p.a. spincoating or laminating of permanent and non-permanent photoresists, spincoating of top- / over-coat and colorfilter materials and spincoating or replicating of polyimides etc.
Within Device Processing there are several types of deposition tools available to deposit those materials.
These tools are:
- Deposition tools for evaporating or sublimating metals, oxides ad organic materials (O-led).
- A KDF sputter tool for DC sputtering of Chromium, Aluminum and ITO as well as RF-sputtering of SiO2.
- An Oxford PECVD tool for
Silicon-Nitride (Si3N4) layers.
This tool is embedded in a encapsulation. cluster tool, consisting of a evaporation tool for Calcium deposition, several gloveboxes (N2 atmosphere) and the above mentioned Oxford PEcvd tool. - Spincoaters like closed cup Gyrset
spinners from Karl Suss, a BLE closed cup spinner and
several open bowl spinners like convac or Polas. - Printing: like screenprinting, flexoprinting and inkjetprinting.
- Hot roll laminators
- Replicating tool
Evaporation tools
Within Device Processing a number of evaporation systems are used in different projects.
An example is:
A Balzers BAK 760 (e-gun) system used for deposition of metals (Al, Cr) on relativelly large substrates
(15 substrates of 6x5 or 6x6 inch or three substrates fitting within a 21inch diameter ).
During evaporation the substrates are rotated in a planetary way to ensure the deposition of an homogeneous layer.
KDF sputtertool
A KDF 744NT is used to deposit several LCD related materials.
The 744NT is a large area, four-target, batch sputtering system, designed for processing large substrates of glass, plastic, or 200 mm silicon wafers.
It is equipped with a high-vacuum loadlock configured with a substrate pre-heat that enables the tool's high throughput.
A pallet area of 19 x 19 inches holds various substrates and sizes (up to 14 inch square).
Inside the chamber there are four targets; Chromium, Aluminium, SiO2 and ITO (Indium Tin Oxide),
an etching stage and 2 substrate heaters: one in the loadlock and one in the deposition chamber.
Thin Film Encapsulation Device
This device is specially built to evaporate materials like Ba, Al, . (max. size 450*250mm) and/or to cover surfaces with SiN, SiON or SiOx layer in a very dust free environment.
The main field of application area is all kinds of surfaces which need to be protected against moisture and/or oxygen.
Screen printing
We have a ESC SMT40 screenprinter available.
Substrates up to 6x6inch can be printed on this machine.
Besides the printer there is other equipment available as there is:
1) A hotplate which is used for levelling paste after printing,.
2) Ovens for firing dielectric glass layers.
Flexo printing
The goal is to apply a structured (thin) layer of e.g. Poly Imide a material used in LCD screens.
Equipment available is a Desktop printer from Nakan Ltd Japan for small sized glassplates. The anilox roll is made of ceramic material.
Due to this, a large range in viscosity can be used. The desktop printer is called the T150.
Inkjet printing
Inkjet printing is a very versitile technology which is applied to deposit materials locally on a substrate.
It is based on the formation of very small droplets of a solution of the to-be deposited materials.
The droplets are made in a printing head, which is a complex device able to create droplets as small as 50 pl.
This print head consists of a capillary (nozzle) which can be activated by a piezo actuator.
By applying a voltage on the piezo element droplets in the order of 50 pl are formed.
A multi-nozzle printhead consists of a large number of nozzles which can all be activated separately.
Depending on the type of printhead droplets of approximately 20 pl are jetted.
Fig. 1Within Device Processing IJ printing is primarely used for realizing Polymeric LED based displays.
For this aim the three different light emitting polymers and a conductive polymer (= PEDOT) material are printed in a pixel structure on a substrate. All display pixels are filled separately by moving over the complete display plate line by line.
For realizing larger displays with smaller pixels, the process times increase considerably.
Therefore multi-nozzle printers are used. Depending on the print strategy and the type of display, a number of pixels can be printed simultaneously.
In the prepilotline of Device Processing two pedot- and four color printers are operational for process optimisation and material research.
To print displays larger than 6 inch a new four color ink-jet printer has been developed.(Fig. 1)
The printer consists of four printheads and one large print table.
Before printing the display plates are exposed to a plasma treatment to obtain the ideal print conditions.
To apply the plasma treatments two types of apparatus are available.
Good wetting of the ITO surface is required to fill the complete pixel, while a bad wetting of the resist is necessary to prevent overflow to the neighbour pixels.
An oxygen plasma of a few minutes results in a clean surface and a good wetting.
Because of the versatility of this method to deposit structured films directly without photolithography on a substrate, various other applications are investigated.
