Chapter 12, Problem 12.128P

a.

Interpretation Introduction

Interpretation:

The number of wafers that can be made from $\text{Si}$ ingot is to be calculated.

Concept introduction:

Density is defined as mass per unit volume. Mass and volume are physical quantities and the units of mass and volume are fundamental units. Density is the ratio of mass to the volume. The unit of volume is derived from the units of mass and volume. The SI unit of density is ${\text{kg/m}}^{\text{3}}$. The formula to calculate density is,

  $\text{Density}=\frac{\text{Mass}}{\text{Volume}}$        (1)

The formula to calculate the volume of the cylinder is as follows:

  $V=\pi r^{2}h$        (2)

Here,

$r$ is the radius of the cylinder.

$h$ is the height of the cylinder.

(b)

Interpretation Introduction

Interpretation:

The mass of a wafer is to be calculated.

Concept introduction:

The formula to calculate the mass of the cylinder is as follows:

  $M=\pi r^{2}hd$        (5)

Here,

$M$ is the mass of the cylinder.

$r$ is the radius of the cylinder.

$h$ is the height of the cylinder.

$d$ is the density of the cylinder.

(c)

Interpretation Introduction

Interpretation:

The balanced equation for the removal of the oxide layer on the wafer is to be written.

Concept introduction:

In a balanced chemical equation, the total mass of reactants and products are equal in a balanced chemical equation, thus, it obeyed the law of conservation of mass. Also, the amounts of substances in a balanced chemical reaction are stoichiometrically equivalent to each other.

Displacement reactions are those in which substances on both sides of the equation remain the same but the atoms exchange places in order to form the product. Displacement reactions can be further classified as a double displacement reaction and a single displacement reaction. In double displacement reaction, both the reactants are the compounds and in single displacement reaction, one of the reactants is an element. The general representation of a double displacement reaction is:

  $\text{AB+CD}\to \text{AD}+\text{CB}$

(d)

Interpretation Introduction

Interpretation:

The moles of $\text{HF}$ required per wafer is to be calculated.

Concept introduction:

Stoichiometry of a reaction is utilized to determine the amount of any species in the reaction by the relationship between the reactants and products.

Consider the general reaction,

  $\text{A}+2\text{B}\to 3\text{C}$

One mole of $\text{A}$ reacts with two moles of $\text{B}$ to produce three moles of $\text{C}$. The stoichiometric ratio between A and B is 1:2, the stoichiometric ratio between A and C is 1:3 and the stoichiometric ratio between B and C is 2:3.