Developments in Ceramic Materials Research

246
Li Chen
The continuing evolution of the ceramics and the associated technologies is accelerating
rapidly. With the advances of understanding in ceramic chemistry, crystallography and the
more extensive knowledge gained in regard to the production of advanced and engineered
ceramics that the potential for these materials has been realised. One of the most prominent
examples of this rapid and accelerating technological development is the electronics industry,
in specific the simple transistor. The concept of the simple transistor is believed to be one of
the most significant electronic engineering achievements in the last century. The demand for
miniaturisation and packing the maximum amount of transistors into the smallest space spurs
the development in ceramic application for packing in the electronics industry.
Brittle by nature, ceramics having a complex chemistry and requiring advanced
processing technology and equipment to produce, perform best when combined with other
materials such as metals and polymers, which can be used as support structures. Ceramic
material is mechanically very hard and stable. Oxide ceramics possess properties such as
oxidation resistant, chemically inert, electrically insulating, generally low thermal
conductivity, slightly complex manufacturing and relatively low cost. Advanced ceramic
material provides an advantage that a metal via can be easily buried inside the soft substrate
before the material goes through the high temperature hardening treatment. This unique
feature makes it feasible to construct multilayer electrical circuit interconnections. It
therefore, provides the possibility to mount electronics components and circuitry directly onto
both sides of ceramic substrate. This intrigued the birth of a new idea that if micro field
emitter matrix pixels can be produced entirely on a mirror flat front side of a ceramic
substrate, and are electrically connected to the backside drive and control circuit; this allows
the structure of micro field emitters built right up to the edge of ceramic substrate. If this is
achievable, it compares favourably with the soda-lime glass substrate, where the column and
the row electrode connections of the micro field emitter matrix on the back plane of a FED
have to be allocated to the sides of substrate. To make it even more attractive, a large size of
display can be constructed by tiling up the ceramic substrates precisely.
In FEDs, small spacers have to be allocated between the anode screen and cathode
substrate to create a vacuum space for electron beams to travel. Candidates for spacer have to
be mechanically strong to sustain the atmospheric pressure, and to be highly insulating to
sustain the high electrical potential without electric break down. Amazingly, ceramic material
has already been proposed as a spacer to support the faceplate phosphor screen against the
cathode back plane in the FED application [35, 36]. This is because the modern ceramics
technology has provided new materials with better performance than other candidate
materials such as glass and polymer.
In the following section, an experimental study on a successful fabrication of the Spindt
type micro tip field emitters on ceramic substrate is presented. A systematic electrical
characterisation of these micro field emitters was carried out. The acquired experimental data
were analysed and the field emission electrical performance were evaluated.