The 335 mm diameter center opening in the ACR-335UT rotary table easily accommodates large 300 mm (12-in.) semiconductor wafers, allowing for extraction of the chip dies from the wafer during semiconductor assembly manufacturing processes or dual side wafer inspection.
The ACR-335UT direct drive rotary table from IntelLiDrives adapts linear motor technology, coupled with precision bearings, to provide faster and more accurate handling of the 300 mm semiconductor wafers.
Presently, semiconductor assembly equipment manufacturers do only limited wafer rotation, but ACR-335UT stage goes 360°, at up to 300 rpm speed.
This large angle wafer rotation can be done without a need to align wafer carrier before placement on the table, thereby increasing throughput. An XY table that carries the rotary table is used for linear Cartesian Alignment. The large open center allows equipment above and below the table to extract pre-cut integrated circuit dies cut from the 300 mm wafer or to do dual side wafer measurement and inspection.
Today’s mechanical drive technologies used in processing 200 mm (8-in. wafers) such as gear drive, worm drive and belt all lack positioning stiffness and accuracy. While worm gear rotary tables can fully rotate wafer, its speed is in single digit rpm. Belt drives can rotate at high speeds, but low belt stiffness and high drive inertia results in low accuracy and poor dynamics.
While these characteristics could be tolerated in the past, it was not until the advent of the large semiconductor wafers that a high accuracy, precise and large open aperture rotary actuator was needed.
The ACR-335UT rotary table is essentially a linear motor “curved” to form a ring. There are 16 RotoLinear motoring modules (up 24 modules can be installed for higher torque capability) within the ring that forms the motor. Axial placement of these modules along with the ultra-thin bearing system allowed the design of this very low profile rotary stage.
The positioning stiffness of the direct drive ACR-350UT rotary table allows it to achieve and to maintain arc-sec accuracy at hundreds of rpm and excellent dynamics even during fast Cartesian (XY) wafer indexing.
Vital yet challenging were the tight tolerances on the axial and radial bearings that allowed to achieve both axial and radial run-outs well under 10 microns.
Interest in AccuRing Ultra-Thin large aperture rotary tables is also coming from general automation applications as well, where design engineers can take advantage of the large center opening to access indexed parts both from inside and outside of the ring simultaneously, resulting in smaller foot print and increased productivity.