LOWER MASK COSTS
Low Mask Costs Through Tela’s Mask-Lite™ Approach
Photolithography masks are a main driver to the increase in per design NRE costs. At each successive process node there is an increasing amount of Optical Proximity Correction (OPC) treatment to designs to ensure accurately printed patterns on wafer. This increases mask write times and mask inspection times driving up the cost of masks at each successive process node.
The figure below shows the costs of a mask set for a single design at each successful process node.
Tela’s 1D technology enables significant reduction in mask cost through:
- Significant reduction in OPC treatment. When patterning 1D geometries, the printed patterns match the designed patterns with minimal required OPC treatment.
- Mask-Lite technology. By splitting the Tela derived 1D patterns into a combination of simple straight lines and cuts, the cost of laser written simple line masks is approximately 10% of complex e-beam written 2D pattern masks.
The figure below shows Mask-Lite™ design to silicon flow. The flow decomposes a Tela 1D layout into line patterns and cut patterns. The line patterns will be printed on the wafers using a simple, low-cost line mask. The cut pattern can be printed on the wafers using a cut mask or using a direct write e-beam tool.
The table below shows the approximate costs associated with a full mask set at 90nm for traditional 2D designs, for designs using Mask-Lite (line mask+cut mask) and designs using Mask-Lite with an e-beam tool for line cuts and via holes. It illustrates the savings in mask costs for a foundry that produces 20 new designs per year with a typical run of 6 wafers per design per year. The 6 wafers per year per design is used to calculate the cost of using the e-beam tool in production.