Advanced Binary
A binary photomask is composed of transmissive (clear) and opaque elements which form one layer of a circuit pattern. Light passes through the transmissive elements, exposing a pattern on the wafer.
Production of an advanced binary photomask with very tight critical dimensions have an enormous potential to boost the performance of our customer's products, in addition to improving their wafer yields. Generally speaking, the tighter the critical dimensions of a device, the faster the speed of the device. Also, shrinking the linewidths of devices allows more devices to be put on each wafer, leading to increased productivity.
Toppan Photomasks' Optical Proximity Correction
We are proud of our capability to support the broad range of optical proximity correction (OPC) techniques required by the leading semiconductor manufacturers.
OPC embeds non-printing subresolution features onto a mask. While there are many different OPC techniques, they all use ultra-small features to compensate for how the light modifies the mask pattern when it reaches the wafer.
Using steppers to pattern wafers with subwavelength features causes what is known as 'proximity effects'.
'Proximity effects' include:
- closed contacts (or holes)
- shortened or rounded lines
- topographic effects (underlying wafer layers)
These proximity effects can cause a rectangle pattern in a photomask to print as an oval on the wafer because light has a tendency to round off edges.
As feature sizes decrease, we must correspondingly reduce the error budgets and the process latitude. Extending stepper lithography means that masks are now used for more than a patterning tool, they actively overcome challenges of shaping light and assist in achieving a design's critical dimensions.
Adding OPC features to our high-quality masks virtually eliminates proximity effects and results in improved resolution and process latitude.