The development of 193nm immersion lithography (193i) has been faster than any previous lithography technologies. The total transition period from proof-of-concept to delivery of mass production tool took only about 4 years. Now, 193i has been widely used in manufacturing advanced microelectronic devices down to 45nm half-pitch node. This course is proposed as a comprehensive guide to the process of 193nm immersion lithography (193i) as well as its related process technologies. It will be focused on the materials and processes topics rather than the specific issues of immersion optics.

Section 1 briefly introduces the advantages of 193i and its challenges. During lithography, a key tool is the track, which provides all of the material processes except exposure.

The track process is discussed in Section 2.

Section 3 covers the leaching tests and water contact angles, which are very immersion-specific topics.

Topcoats have been popularly used in the 193i process to prevent leaching of resist components into the water. The immersion resist with low leaching levels are maturing and gradually replacing the topcoat process.These topcoat or topcoat-less processes and selections are discussed in Section 4.

Defectivity is a major concern for 193nm immersion lithography as water is in direct contact with the resist stack during exposure.

Section 5 provides a comprehensive summary of various immersion-related defects and defect-reduction strategies. The water immersion technique enables the numerical aperture of exposures larger than 1.0 – hyper-NA. The high incident angles characteristic of higher NA 193i exposures impose challenges to anti-reflective control.

Various anti-reflective control strategies and under-layer technologies are presented in Section 6.

There are several advanced resist processes, which have been developed in “dry” lithography, can be and will be adopted by 193i, such as shrink and trim processes. They can further boost the resolution capability of 193i. These are the content for Section 7.

In combination with 193i, double exposure and double patterning have emerged as a prime candidate for 32nm half-pitch and have the possibility to extend to 22nm node. Section 8 collects various double exposure and double patterning approaches as well as some earlier results.

Line-edge roughness and line-width roughness of resist patterns have been a concern for many years. The roughness formation has been attributed to both materials and process conditions. Numerous roughness reduction methods have been proposed and investigated. Section 9 is dedicated to these topics.

Encouraged by the great success of water immersion, there was a considerable interest in further boosting NA through the use of fluids and lens materials with higher indices of refraction – 193i+. This interest decreased dramatically in mid 2008 because the 193i+ tool appears to be too late for the 32nm node due to the lack of high refractive index materials. However, 193i+ is still an interesting technology as it promises much lower cost-of-ownership than double patterning and EUV. The major learning in developing 193i+ is beneficial to hyper-NA water immersion and other lithographic technologies.Thus, Section 10 is included in this course to briefly cover 193i+.