Advanced Wafer Fabrication Technology Quiz

Questions and Answers

What is the primary purpose of diffusion in wafer fabrication?

To remove impurities from the silicon surface

To introduce dopants into silicon to control majority carrier type (correct)

To reduce the temperature of the silicon wafer

To increase the size of silicon wafers

What are the two steps of the diffusion process?

Saturation and Ionization

Predeposition and Drive-in (correct)

Evaporation and Condensation

Heating and Cooling

What factor does NOT affect the junction depth in diffusion?

Substrate Dopant Concentration

Temperature

Dopant Ion Dose (correct)

Time

Which characteristic of ion implantation process is TRUE?

Can utilize a wider range of impurity species Signup and view all the answers

Which statement is true regarding the Drive-in step of diffusion?

The dopants must be predeposited before this step Signup and view all the answers

What is the primary outcome of lattice damage during ion implantation?

Knocking atoms out of the silicon lattice Signup and view all the answers

How does temperature impact junction depth during diffusion?

Increased temperatures increase junction depth Signup and view all the answers

Which of the following factors in ion implantation controls the maximum concentration of dopants?

The acceleration energy of the ions Signup and view all the answers

Study Notes

Diffusion

Dopants like boron and phosphorus are introduced into silicon to control the majority carrier type and resistivity.
The process involves the movement of atoms from regions of high concentration to low concentration.
Diffusion depends on temperature and time, comprising two main steps:
- Predeposition (Constant-Source Diffusion): Occurs with a continuous supply of dopants.
- Drive-in (Limited-Source Diffusion): Takes place after predeposition, where dopants already present are driven deeper into the silicon.

Junction Depth

Junction depth is achieved when the concentration of diffused dopants equals that of the substrate.
Factors increasing junction depth include:
- Elevated Temperature
- Extended Time
Detailed calculation of junction depth is a topic in Advanced Wafer Fabrication Technology.

Ion Implantation

Involves accelerating ionized dopants into the wafer's surface at high energy.
Junction depth influenced by:
- Acceleration energy
- Substrate concentration
Maximum dopant concentration in the wafer is determined by the dose of accelerated ions.

Characteristics of Ion Implantation

Operates at low temperatures, allowing use of sensitive materials like photoresist and metal films as barrier masks.
Capable of utilizing a wider range of impurity species compared to diffusion.
Requires tight process control to ensure precision in doping.
Ion impact can cause lattice damage by knocking atoms out of the silicon lattice, necessitating an annealing process to repair damage.

Description

Test your knowledge on diffusion, junction depth, and ion implantation in semiconductor manufacturing. This quiz covers essential processes like predeposition and drive-in, as well as factors affecting junction depth. Assess your understanding of these critical concepts in advanced wafer fabrication technology.