### 6.5.3 Summary to: 6.5 Lithograpy

| Lithography comprises three elementary steps: |  |
|  | Cover the layer to be structured with a light-sensitive layer called (photo) resist |
|  | Expose the resist to light only where you want the structure by a "slide projector" called stepper (always demagnify the "slide" called reticle. |
|  | Develop the exposed resist in such a way that unexposed parts are etched off. |
|  | The structure has now be transferred into the resist; the process is rather similar to regular old-fashioned analog photography. |
| The problem is that we want to make structures with lateral sizes in the 30 nm region, far smaller than the wavelength of light. This necessitates extreme measures in all components involved |  |
|  | At the core of lithography are the steppers - optical machines for around 5 Mio € a piece |
|  | Resist technology, too, is a highly developed part of lithography |
|  | For some big problems simple solutions have been found. Example: reticles with pellicles |  |

© H. Föll (Semiconductor Technology - Script)