FAQ

Q1 ：What is “sputtering”?

A1 ：When you throw a rubber ball onto a gravel road, some of the gravel will invariably become dislodged. When argon gas is introduced into a vacuum system and is subjected to an electrical discharge, plasma is generated. The argon ions in the plasma are equivalent to the rubber ball, and the negative discharge electrode (target) is comparable to the gravel road. When the argon ions hit the target, the target releases its atoms. This phenomenon is called “sputtering.”

sputtering

Q2 ：How does a sputtering system work?

A2 ：When a glass substrate is placed adjacent to an aluminum target, an aluminum film forms on the glass substrate.
A sputtering system employs this phenomenon to create a thin film on a substrate as required by the intended application.

ITO on Glass Substrate

Q3 ：What is unique about Sanyo’s sputtering process?

A3 ：Our sputtering process utilizes our proprietary facility. In our sputtering system, a plurality of targets can be arranged within a doughnut-shaped tank and a thin film can be formed on each of the substrates. This system is capable of processing multiple large workpieces such as 300-mm-square glass substrates.
Let’s look at the sequence of steps in Sanyo’s thin film forming process.

Sanyo’s thin film forming process (sputtering)

• A jig for holding glass substrates is loaded into a tank.
• A vacuum pump evacuates the tank to a predetermined degree of vacuum.
• The tank is filled with a mixture comprising argon and other gases. The targets are allowed to discharge to form a base film.
• Likewise, ITO targets are allowed to discharge electrical potential to form a thin ITO film on each of the glass substrates.
• Nitrogen gas is injected into the tank.
• Once film formation is complete, the jig is unloaded from the tank.

Q4 ：What is ITO film?

A4 ：ITO is the abbreviation for indium tin oxide. ITO film, a transparent conductive film, is essentially a mixture of indium oxide and tin oxide. Because this film is a transparent conductor that readily transmits light and electricity, it has been used as an electrode in LCDs for more than 20 years.
The conductivity of the transparent conductive layer of an ITO film is related to the electrical resistance of the ITO film; therefore, the thicker the ITO film, the lower the resistance of the ITO film

Q5 ：Please tell me about the methods for ITO film formation.

A5 ：The currently available methods of forming ITO transparent conductive films are shown below.

*Sputter process (Sputtering process)

Among the ITO film formation methods listed above, Sanyo uses mainly the sputtering process to manufacture its ITO transparent conductive film products.

Q6 ：What are some typical applications of ITO films?

A6 ：Typical applications include the following:

Q7 ：What is the scope of processes carried out by Sanyo, ranging from film formation to shipment?

A7 ：We are responsible for the following flow of processes, beginning with the formation of the ITO film and ending with shipment of the product.

Sanyo Vacuum Industries’ processing flow from ITO film formation to shipment

• Glass substrates are inspected upon delivery according to the specifications for unprocessed glass substrates.
  
• The substrates are cleaned in a multilayer ultrasonic rinsing process comprising a wash with a cleaning agent, a rinse with pure water, a rinse with ultrapure water, and a drying cycle.
  
• The cleaned glass substrates are mounted on a jig that is prepared for loading into the sputtering system. Minor flaws and contamination are eliminated, and the substrates are checked for defects.
  
• Sanyo’s unique sputtering system is used to form the thin film.
  
• The jig with the glass substrates is unloaded from the tank and the resistance and transmittance are evaluated.
  
• A specific number of samples are taken from all the substrates, and the optical characteristics are inspected in detail.
  
• Each glass substrate is inspected under fluorescent and halogen lamps.The inspection is intended to detect defects such as scratches, chipping, contamination and pinholes.
  
• The products that satisfy the requirements are packed and prepared for shipment.

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Abbreviations

Abbreviations used on this website and in industries related to thin films are explained below. Please refer to this list for full spellings and definitions.