Question

Design and sketch masks to be used with negative photoresist for making an array of five wires of smallest width 2 µm on a silicon wafer. The wires are to be connected at each end to contact pads (1 mm) for wire bonding. The wires are to be broken to have 20 nm gaps. What technique would you use to do this? The wire to be broken must be thin (no more than 50 nm) but the contact pads need to be thick (1 μm) for wire bonding. Outline the steps you might take to make the final device. You may have to research resist treatments for lift-off.

Answer 1

To design and sketch masks for making an array of wires on a silicon wafer with specific width and contact pad thickness, the technique of photolithography can be used. Steps involved in the process and the use of resist treatments for lift-off are outlined.

Step-by-step explanation:

To design and sketch masks for making an array of five wires of the smallest width of 2 µm on a silicon wafer using negative photoresist, you would use the technique of photolithography. The steps involved in making the final device are as follows:

1. Prepare the silicon wafer by cleaning and applying a photoresist layer.
2. Expose the wafer to UV light through a mask with the desired wire pattern.
3. Develop the photoresist to remove the unwanted areas.
4. Etch the exposed silicon to form the wires.
5. Remove the remaining photoresist to reveal the wires.
6. Deposit a thick layer of material for the contact pads.
7. Pattern the contact pads using a separate mask.
8. Etch the excess material to create the wire gaps.

Resist treatments for lift-off can be used to precisely remove the unwanted photoresist and prevent damage to the wires and contact pads during the process.