Question

1. Let's assume that we want to fabricate a device with 3 lithography steps. During designing of a photomasks, what should we add in the photomask?

(a) Negative lithography mask with alignment patterns in the first two masks.

(b) Positive mask lithography mask with alignment patterns in the first two masks.

(c) Alignment patterns in all masks without depending on the PR type.

(d) Alignment patterns in the first two masks without depending on the PR type.

2. If a device cannot have any trace of Chromium contamination, how do you clean the substrate before microfabrication?

(a) Rinse with acetone.

(b) Treat with Piranha.

(c) Treat with HF acid.

(d) Rinse with deionized water followed by acetone.

Answer 1

Answer -

1. Let's assume that we want to fabricate a device with 3 lithography steps. During designing of a photomasks, what should we add in the photomask?

• The correct option is (b) as positive mask lithography mask is the mask that on the contact of the UV rays became more soluble in nature and the photomask that is created is also positive and more clear in this mask pattern.
• Option (b) - Positive mask lithography mask with alignment patterns in the first two masks.

   2. If a device cannot have any trace of Chromium contamination, how do you clean the substrate before microfabrication?

• The correct option is (a) as to clean the substrate before the microfabrication we have to rinse the rinse the water with the help of Acetone so that it is fully cleaned and to achieve that we thoroughly rub the surface with the cloth .This will help in cleaning the substrate.
• Option (a) - Rinse with acetone.