System Data Path
Wafer writing begins with scanning the wafer to establish alignment features and for each head to negotiate with its neighbors for track to track head alignment. The interferometers and Nano Actuators move the heads such that each head will write 254,000 100nm channels (1 inch) and that each head is perfectly aligned with its neighbor.
The mask data base is sent to the control computer. Since each channel is separately collimated, proximity correction is not necessary. The data is rasterized into 12 stripes for a 300mm wafer, one for each head. The data is repeated for each die or can be written as a whole wafer. Since there is no mask, die size limits are arbitrary.
The wafer transport system is mapped and X variation data is sent to the data controller so the write timing can be adjusted.
Data Rate Calculation
Each print head needs 62.5MB/s mask raster data to write to all of the 254K accelerators. This can easily be accomplished with 8 - 10Mb/s SerDes channels of Hybrid Memory Cube Gen 3.
The pixel data rate is computed as the binary write with no gray scale. The wafer moves in the X direction at 40mm/sec with 20nm pixels, so:
40e-3 / 20e-9 / 8 = 2e6 writes/s
254,000 channels * 2e6 writes/s = 5.08e11/s per head or 62.5MB/s
The Avago MiniPOD™ AFBR-814VxyZ operates at 14.0625 Gbps for IB-FDR with 64b/66b encoded data per fiber and has 12 receivers per POD.
5.08e11 /14e9 = 36 fibers or 3 PODs
The total data rate for all 12 heads is 0.75TB/s per station or 1.5TB/s for a twinscan configuration.