Introduction

There are various methods for manufacturing optical thin films, broadly categorized into three types: Physical Vapor Deposition (PVD), Chemical Vapor Deposition (CVD), and Chemical Solution Deposition(CSD).

1. Physical Vapor Deposition (PVD) Technology

In PVD technology, the deposition material comes directly from the source material (referred to as the coated material). It involves three basic processes: generation of vapor-phase deposition material, transportation of vapor-phase deposition material, and deposition of vapor-phase deposition material.

(1) Generation of Vapor-Phase Deposition Material
There are two ways to generate vapor-phase deposition material:

a. Evaporation Coating: The deposition material is heated and evaporated to form vapor-phase deposition material, known as evaporation coating.

b. Sputtering Coating: High-energy particles bombard the target material, causing atoms of the target material to be ejected and become vapor-phase deposition material, known as sputtering coating.

(2) Transportation of Vapor-Phase Deposition Material
The transportation of vapor-phase deposition material must be carried out in a vacuum of less than 1.33x10^-2Pa. This is done to:

a. Reduce collisions and chemical reactions between vapor-phase deposition material and other gas molecules during its flight towards the substrate (referred to as the substrate).

b. Minimize chemical reactions between the deposition material, vapor-phase deposition material, and the substrate with other reactive gas molecules.

c. Prevent other gas molecules from entering the film layer and becoming impurities during the deposition process.

d. Improve the deposition speed, purity, density, and adhesion of the thin film to the substrate.

(3) Deposition of Vapor-Phase Deposition Material
Deposition of vapor-phase deposition material is the process of vapor-phase deposition material atoms condensing on the substrate. This can occur through natural condensation or by introducing other reactive gas atoms to form compound films through chemical reactions, known as reactive deposition. Additionally, during the process of vapor-phase deposition material atoms condensing into a film on the substrate, high-energy ions can be simultaneously used to bombard the film layer to improve its structure, properties, and adhesion, known as ion deposition.

2. Chemical Vapor Deposition (CVD) Technology

Chemical Vapor Deposition is a technique where chemical substances in gaseous or vapor form undergo chemical reactions on a gas-solid interface using various energy sources such as heating, plasma excitation, or light radiation within a reactor to form solid deposits.

3. Chemical Solution Deposition (CSD) Technology

The solution deposition method involves the formation of films on the substrate surface through chemical reactions in a solution. It includes methods such as chemical deposition, electrochemical deposition, and sol-gel (SG) deposition.