What is photolithography in IC fabrication?

Photolithography, also called optical lithography or UV lithography, is a process used in microfabrication to pattern parts on a thin film or the bulk of a substrate (also called a wafer). In complex integrated circuits, a CMOS wafer may go through the photolithographic cycle as many as 50 times.

How are integrated circuits manufactured?

In the manufacturing process of IC, electronic circuits with components such as transistors are formed on the surface of a silicon crystal wafer. A thin film layer that will form the wiring, transistors and other components is deposited on the wafer (deposition). The thin film is coated with photoresist.

What are the two processes involved in photolithography?

Photolithography is the process of transferring geometric shapes on a mask to the surface of a silicon wafer. The steps involved in the photolithographic process are wafer cleaning; barrier layer formation; photoresist application; soft baking; mask alignment; exposure and development; and hard-baking.

How are photolithography masks made?

Photomasks are made by applying photoresist to a quartz substrate with chrome plating on one side and exposing it using a laser or an electron beam in a process called maskless lithography. The photoresist is then developed and the unprotected areas with chrome are etched, and the remaining photoresist is removed.

What are integrated circuits?

integrated circuit (IC), also called microelectronic circuit, microchip, or chip, an assembly of electronic components, fabricated as a single unit, in which miniaturized active devices (e.g., transistors and diodes) and passive devices (e.g., capacitors and resistors) and their interconnections are built up on a thin …

When was photolithography invented?

PHOTOLITHOGRAPHY: is the act of making a lithographic printing plate by photo- graphic means. A French chemist, Alphonse Louis Poitevin, invented it in August 1855.

What is the process of photolithography?

Photolithography is a patterning process in which a photosensitive polymer is selectively exposed to light through a mask, leaving a latent image in the polymer that can then be selectively dissolved to provide patterned access to an underlying substrate.

Where are integrated circuits produced?

Table 2: Top Global Analog Integrated Circuit Suppliers by Revenue*

	Company	Geographic Areas Where the Most Revenue is Generated**
1	Texas Instruments	China including Hong Kong
2	Analog Devices	United States
3	Skyworks Solutions	—
4	Infineon	China, USA, Asia-Pacific

What are integrated circuits made up of?

What is mask fabrication?

Mask making is a fabrication process where a computer-aided design (CAD) is transferred to a thin (80-100 nm) layer of metal in a glass or fused silica substrate, known as mask or photomask. The metal works as an absorption layer for light at different wavelengths.

What is a photolithography mask?

A photolithography mask is an opaque plate or film with transparent areas which allows light to shine through a defined pattern. They are commonly used in photolithography processes, but are also used in many other applications by a wide range of industries and technologies, notably microfluidics.

What are photomasks in photolithography?

A set of photomasks, each defining a pattern layer in integrated circuit fabrication, is fed into a photolithography stepper or scanner, and individually selected for exposure. In multi-patterning techniques, a photomask would correspond to a subset of the layer pattern.

Why are photomasks becoming more and more complex?

And as transistors have become smaller and smaller, photomasks have become more complex to accurately transfer the pattern to silicon wafers. The process of creating photomasks has become correspondingly more advanced—even slight defects in a photomask can impact silicon device performance.

How many photomasks does it take to make a device?

One device requires a “mask set.” In other words, a single device may require between 5 to 40 (or more) individual photomasks, called a “mask set,” according to Compugraphics. One mask is used for each step in the fabrication process, according to Compugraphics.

What is the difference between photomasks and wafers?

2. The manufacturing of photomasks is basically equal to the wafer fabrication. The difference is the exposure of the resist which is done by electron beams (photomasks) or with optical lithography (wafer). First step is the exposure of photoresist with electron beams (or laser).