What is a Mask Aligner and its Important Aspects?

A Mask aligner is an instrument that enables photolithography, otherwise known as optical lithography. The mask alignment systems work in the principle of the microfabrication process. With the implementation of this process, the instrument selectively removes parts of a thin film in order to create a pattern or design on the substrate.

How does the mask aligner works?

An aligner or a mask alignment system uses the photolithography principle to produce integrated circuits. This process shares some of its basic principles with photography. The mask aligner manufacturers use the pattern to the photoresist etching that is created through light exposure either using a photomask or with a mask. Such a procedure provides more precision than the printed circuit boards.

In the mask alignment systems, the aligner keeps the photomask over the silicon wager as a bright light focused through the mask and onto the photoresist. Since the instrument's ability to align photomasks precisely at the same locations frequently as the chip undergoes numerous rounds of lithography, it's a perfect machinery tool to manufacture semiconductors.

The major components of the mask aligner

• Ultraviolet light source

The mask aligner can't make the substrate shone through in a controlled way if the light source is not of high quality. In the traditional mask alignment system, there has been the use of broadband mercury bulb to provide a single spectrum of light. Modern technology uses ultraviolet light sources in the mask aligner. The UV wavelengths are not transited to the bulb in 100nm and 400nm wavelength. There has been more advancement in UV LED since the mask aligner manufacturers focus on developing the quality and performance of the system.

• Optical elements

The optical elements are incorporated in the mask alignment systems to shape the beam of light. As a result, it forms uniform illumination all across the substrate that would get processed. The UV source passes through various optical elements such as ellipsoidal mirror, cold light mirror, heat sink, shutter, Fly's eye, condenser lens, filter plates, front mirror, and front lens.

• Mask holder

The mask holder is responsible for holding the component in place as the photomask contains the pattern that has to be transferred to the substrate. The mask aligner manufacturers make the holder in such a way, so it would not allow the photomask to move while the alignment procedure is in the process.

• Substrate holder

The substrate holder is also known as wafer chuck, which is responsible for holding the substrate in its appropriate position in the mask alignment systems. The substrate is held against its surface with a slight application of vacuum to the chuck and via alignment pins to mark the precise points. The holder's motion can be transformable to produce precise alignment of the features imprinted on the mask onto the substrate.

• Microscope

Generally, there are two microscope components present in the mask alignment system. Both the microscope arms are used to locate the alignment targets on the substrate and the photomask. They can also move the substrate on the wafer chuck onto its prior position. The mask aligner manufacturers incorporate a microscope system in the mask aligner, so the users can view the photomask and the substrate to perform a close inspection of them and align all the essential features to one another with preciseness.

All the above key components work together to determine the resolution and alignment of the semiconductors. If one of them does not function properly, the lithographic process will contain an inaccuracy. If you want to get more information regarding mask aligners, get in touch with Neutronix Quintel. Visit their website https://neutronixinc.com for further contact details.