Photoresist layer is formed using a light-sensitive polymer.

Explanation:
The photoresist layer is an essential component in the photolithography process used in semiconductor manufacturing. It acts as a light-sensitive material that undergoes a chemical change when exposed to ultraviolet (UV) light or other forms of electromagnetic radiation. The photoresist layer is used to transfer the desired pattern onto the substrate during the fabrication process.

Properties of a light-sensitive polymer:
- Light sensitivity: The polymer used in the photoresist layer should have high sensitivity to light, particularly in the UV range.
- Chemical reactivity: The polymer should undergo a chemical change, such as cross-linking or solubility change, when exposed to light. This change enables the transfer of the pattern onto the substrate.
- Stability: The polymer should retain its chemical properties and stability when stored or during the fabrication process.
- Adhesion: The polymer should adhere well to the substrate surface to ensure proper pattern transfer and avoid any delamination issues.
- Resolution: The polymer should have good resolution capabilities to accurately reproduce the desired pattern.

Other options:
a) High-sensitive polymer: This option is incorrect because it does not specify the type of sensitivity required for the photoresist layer.
c) Polysilicon: Polysilicon is a semiconductor material used in various electronic devices but not in the formation of the photoresist layer.
d) Silicon dioxide: Silicon dioxide is an insulator material commonly used in semiconductor manufacturing for various purposes, but it is not used to form the photoresist layer.

In conclusion, the correct option is b) light-sensitive polymer because it fulfills the necessary requirements for a photoresist layer, including light sensitivity, chemical reactivity, stability, adhesion, and resolution.