According to their different uses, they can be divided into those used for chip production, packaging, and LED manufacturing.
According to the different light sources, they can be divided into ultraviolet light sources (UV), deep ultraviolet light sources (DUV), and extreme ultraviolet light sources (EUV). The wavelength of the light source affects the process of the lithography machine.
The extreme ultraviolet lithography machine has adopted a new approach to further provide shorter wavelength light sources. The main method currently used is to irradiate an excimer laser onto a tin droplet generator, exciting 13.5nm photons as the light source for the lithography machine. ASML is currently the only manufacturer in the world capable of designing and manufacturing EUV lithography equipment.
According to different operating methods, it can be divided into contact lithography, direct writing lithography, and projection lithography.
contact printing
Contact Printing
The mask plate is in direct contact with the photoresist layer. The resolution of the exposed pattern is comparable to that of the pattern on the mask plate, and the equipment is simple. According to the method of applying force, contact can be divided into soft contact, hard contact, and vacuum contact.
1a. Soft contact refers to the process of attaching a substrate onto a tray (similar to the substrate placement method of a glue spreader), with a mask covering the substrate;
1b. Hard contact is the process of pushing the substrate upwards under a pressure (nitrogen) to make contact with the mask plate;
1c. Vacuum contact is the process of extracting air between the mask plate and the substrate to ensure better adhesion.
Features: photoresist contamination mask board; Mask plates are prone to damage and have a short lifespan (only 5 to 25 uses); Easy to accumulate defects.
Proximity lithography
Proximity Printing
There is a small gap (approximately 2.5-25 μ m) between the mask plate and the bottom layer of the photoresist substrate. It can effectively avoid damage to the mask plate caused by direct contact with photoresist, making the mask and photoresist substrate durable for use; The mask has a long lifespan (which can be increased by more than 10 times) and fewer graphic defects. Proximity lithography is widely used in modern photolithography processes.
