Nov 30 2007
With an estimated 90% of failures in robotic handling systems being caused by improper wafer placement, semiconductor OEMs are, understandably, looking for ways to combat the problem.
For some, this may mean heavy investment in the development of highly sophisticated optical sensing technology. However, for one manufacturer at least, a humble ceramic component will be instrumental in helping to reduce damage in the wafer handling system of its new fabrication facility.
Morgan Advanced Ceramics has been working with a chip manufacturer and an OEM partner to develop a new ceramic end effector capable of handling large diameter wafers. A product for 300mm wafers is already in production and a 450mm version is in development.
The key to the system is the structural strength and stiffness of Alumina ceramic – it does not bend like its aluminium equivalent. If forced, the Alumina ceramic will break, thereby minimising potential damage caused to the equipment and enabling straightforward replacement.
The stiffness of the Alumina ceramic also allows construction of a component that is thinner than one made in aluminium. The thinner, lighter end effector puts less load on the arm of the placement machine, which allows it to be run faster and wafers can be stacked closer together. All these factors contribute to greater productivity.
Optical sensors at the two tips of the end effector ensure correct placement of the wafers, counts them and eliminates the possibility of two wafers being placed together, an issue which leads to costly wastage and in some cases, malfunction.
With upwards of £4 billion invested to bring a fabrication unit on line manufacturers are focused on ensuring quick return on investment. To achieve this, planned - and most importantly un-planned, downtime needs to be minimised. As a result, all parts of the system must come under the spotlight – even at component level.
The ceramic chosen for the new end effectors is 99.5% Alumina, a strong yet brittle material that will support the heavier, larger diameter wafers. The disk shaped component is four millimetres thick at the base (where it houses the wiring for the optical sensors) and just one millimetre at the thinnest point.
Yannick Galais of Morgan Advanced Ceramics commented: “Semiconductor manufacturers are beginning to realise that in some cases, innovation at component level can offer significant improvements in yield and productivity.”