Question

When the photoresist coating (during IC fabrication) is exposed to ultraviolet light, the photoresist becomes :

• A. Oxidized
• B. Ionized
• C. Polymerized
• D. Brittle

Hint:

In photolithography: \[ \text{UV exposure} \Rightarrow \text{Polymerization of photoresist} \] which helps create IC patterns on wafers.

Answer 1

The Correct Option is C

Concept: Photolithography is an important IC fabrication process used for pattern transfer. Photoresist materials undergo chemical changes when exposed to ultraviolet (UV) radiation.

Step 1: Understand photoresist. Photoresist is: \[ \text{Light-sensitive polymer coating} \] applied on semiconductor wafer. It is used to create desired patterns during fabrication.

Step 2: Effect of ultraviolet exposure. When UV light falls on photoresist:
• Chemical reactions occur.
• Polymer chains become cross-linked.
• The exposed region hardens. This process is called: \[ \text{Polymerization} \]

Step 3: Explain practical significance. After polymerization:
• Certain regions resist chemical etching.
• Required circuit patterns can be transferred onto wafer. Thus polymerization is central to photolithographic pattern formation.

Step 4: Analyze other options. Oxidized Oxidation is not the main photochemical transformation. Ionized Ionization is not the intended lithography process. Brittle Hardening may occur indirectly, but the correct scientific process is polymerization.

Step 5: Write final answer. Hence the correct answer is: \[ \boxed{\text{Polymerized}} \]