This invention relates to carriers used in the semi-conductor fabrication industry, and in particular to tray carriers with covers.
Trays are used in the micro-electronic industry for storing, transporting, fabricating, and generally holding small components such as, but not limited to, semi-conductor chips, ferrite heads, magnetic resonant read heads, thin film heads, bare dies, bump dies, substrates, optical devices, laser diodes, preforms, and miscellaneous mechanical articles such as springs and lenses.
Semi-conductor chips (chips) are illustrative of the issues associated with handling the above-defined components. Semi-conductor chips are very small electronic devices which, for purposes of economy and scale, are manufactured en-masse from a larger semi-conductor wafer (wafer). Typically, a single wafer will yield several tens or hundreds of chips. Often, after the wafer has been segmented into individual chips, additional processing is necessary. This usually entails transporting a plurality of chips from one workstation to another for processing by specialized equipment.
To facilitate processing of chips on a large scale, specialized carriers called matrix trays (trays) have been developed. These trays are designed to hold a plurality of chips in individual processing cells or pockets arranged in a matrix or grid. The size of the matrix or grid can range from two to several hundred, depending upon the size of the chips to be processed.
In order to prevent chips from being dislodged, misaligned, or lost from their pockets or cells during processing and transport, retainers are used. Although the typical retainer is in the form of a cover, a second tray may function equally as well. Such retainer is usually placed on the tray so that it is coincident with the tray. The retainer is then attached to the tray by fasteners such as clips. These fasteners can take different shapes, depending upon the configuration and combination of trays and retainers. For example, the fasteners can be a pair of parallely aligned clips which traverse the retainer or tray and grip the tray and retainer at opposing edges. Or, the fastener may be a U-shaped frame with a channel into which the retainer and tray is slidingly inserted. Other fasteners that have been developed are capable of attaching different combinations of trays and trays with retainers to each other. For example, two trays and a cover, six trays and a cover, and two trays.
There are several problems associated with this way of retaining chips within a carrier tray. The clips may be lost or misplaced. They may be damaged or broken. They cannot be easily changed or modified to accommodate different combinations of trays and retainers. And, the ability to effectively fasten may diminish due to aging and abrasion.
Equally important is the problem of particle generation which may lead to chip contamination. Particles may be generated mechanically during clip attachment and removal, and particles may be generated chemically in reaction to various processing fluids. The problems of particle generation are variable because fasteners are manufactured from different materials such as plastic or metal.