Question

Arrange the following fabrication steps of MOSFET from initials:
(A) Metallization
(B) Oxidation
(C) Etching
(D) Diffusion/Ion implantation

• A. (A), (B), (C), (D)
• B. (B), (C), (A), (D)
• C. (B), (A), (D), (C)
• D. (B), (C), (D), (A)

Hint:

In semiconductor device fabrication, the order of processing steps is critical for ensuring that each layer and dopant is applied in the correct sequence to form the device structure.

Answer 1

The Correct Option is A

Step 1: Understand the process of MOSFET fabrication.
The fabrication of a MOSFET involves several key steps that need to be followed in a particular sequence to ensure proper functioning of the transistor. Each of these steps plays a crucial role in forming the MOSFET structure.

Step 2: Order of steps.
- Metallization (A): Metallization is the process of applying metal layers for interconnections. It is typically the first step after the formation of the wafer, as these metal contacts are needed to make electrical connections between the different components of the MOSFET.
- Oxidation (B): The next step involves oxidizing the silicon wafer to form a layer of silicon dioxide, which is used as an insulating layer. This layer is essential for forming the gate dielectric in a MOSFET. It comes before etching and doping steps.
- Etching (C): Etching is used to define patterns on the wafer, particularly for the gate structure and other components of the MOSFET. After oxidation, this step shapes the areas where different materials will be deposited or removed.
- Diffusion/Ion implantation (D): Diffusion or ion implantation is the final step in the fabrication process where dopants are introduced into the semiconductor material to create regions with different electrical properties (e.g., n-type or p-type regions). This step usually comes last to define the transistor's source, drain, and channel regions.

Step 3: Final Answer.
Thus, the correct sequence of MOSFET fabrication steps is:
1. Metallization (A)
2. Oxidation (B)
3. Etching (C)
4. Diffusion/Ion implantation (D)

Final Answer: \[ \boxed{(1)} \]