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Classification of lithography machines

Time:2023-12-26 09:02:45      Click:276

According to the different uses, it can be divided into the production of chips, for packaging and for LED manufacturing.

According to the different light sources, it can be divided into ultraviolet light source (UV), deep ultraviolet light source (DUV), extreme ultraviolet light source (EUV), and the wavelength of the light source affects the process of the lithography machine.

Extreme ultraviolet lithography machine, selected a new scheme to further provide a shorter wavelength light source. At present, the main method is to irradiate the excimer laser on the tin droplet generator and excite 13.5nm photons as the light source of the lithography machine. ASML (ASML) is currently the only manufacturer in the world capable of designing and manufacturing EUV lithography equipment.

Depending on the mode of operation. It can be divided into contact lithography, direct writing lithography and projection lithography.

Contact lithography

Contact Printing

The mask plate is directly in contact with the photoresist layer. The exposed graphics have the same resolution as the graphics on the mask plate, and the equipment is simple. According to the way the force is applied, the contact type is divided into: soft contact, hard contact and vacuum contact.

1a. Soft contact is to adsorb the substrate through the tray (similar to the substrate placement of the glue machine), and cover the mask on the substrate;

1b. Hard contact is to push the substrate through an air pressure (nitrogen) and upward to make it contact with the mask plate;

1c. Vacuum contact is to pump air between the mask plate and the substrate to make them fit better

Features: photoresist polluted mask plate; The mask plate is easy to damage and has a short service life (only 5 to 25 times); Prone to cumulative defects.

Proximity lithography

Proximity Printing

The mask plate and the photoresist substrate retain a small Gap (Gap), about 2.5 to 25 μm. It can effectively avoid the mask plate damage caused by direct contact with the photoresist, so that the mask and the photoresist substrate can be durable. Long mask life (can be increased by more than 10 times), fewer graphic defects. Proximity is the most widely used in modern lithography.

Projection lithography

Projection Printing

Similar to film photography, by pressing the "shutter", light is projected through the lens onto the film and exposed. The image is then obtained through "photo development," which involves soaking the film in a developer. Projection lithography is a mainstream lithography technique for integrated circuits because of its high efficiency and no damage.

3a. Scanning Project Printing

Research began in the late 1970s to early 1980s. The size of the mask plate and the pattern in this lithography machine is 1:1, that is, the size on the mask plate is the same as the size of the pattern on the photoresist. It is called scanning because light shines through a thin slit on the substrate, usually several lines at a time, and the substrate needs to be moved so that the light can expose all the areas.

Features: Process node is 180 nm-130 nm, mask plate 1:1, full size exposure.

3b. Stepping-repeating Project Printing (Stepper)

Research began in the late 1980s and 1990s, using a lens system to project the patterns on the mask onto the base one by one on a small area. After each exposure of a small area, the substrate moves to the next position until the entire substrate has been exposed. An exposure area is a "shot." Because it is projected through the lens system, the general use of 365nm UV light is 5 times the version, that is, the graphic size on the mask version is 5 times the size on the actual photoresist, so more complex graphics can be designed on the mask plate, but it increases the difficulty of the production of the prism system.

3c. Scanning-Stepping Project Printing (also known as Scanner)

Since the end of the 1990s, this model is generally used in high-end semiconductor manufacturing, for ≤ 0.18μm process. During exposure, the mask plate moves in one direction while the wafer moves in sync in the direction perpendicular to it. [4]

Features: Increase the field of view of each exposure; Provide compensation for the uneven surface of the silicon wafer; Improves dimensional uniformity throughout the silicon wafer. However, at the same time, due to the need for reverse motion, increasing the accuracy requirements of the mechanical system, the Scanner usually has higher production efficiency than other exposure machines, the design and manufacture are very complex, and the purchase and maintenance costs of the Scanner are high.

High precision duplex lithography

It is mainly used in the development and production of small and medium-sized integrated circuits, semiconductor components, optoelectronic devices, surface acoustic wave devices, thin film circuits and power electronic devices.

Double-sided lithography machine includes motion control system, image processing system, system software and data I/O processing control unit [5].

High precision single side lithography

For universities, enterprises and scientific research units, a high-precision lithography machine is developed for the characteristics of lithography machine, small and medium-sized integrated circuits, semiconductor components, optoelectronic devices, surface acoustic wave devices development and production.

High precision alignment table, binocular separate field of view CCD microdisplay system, exposure head, pneumatic system, vacuum tube system, direct connection oil-free vacuum pump, shock-proof table and accessory box.

To solve the problem of non-circular substrate, fragmentation and uneven substrate caused by the partition of the plate can not be aligned.

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