Adapting immersion exposure to mass production by adopting a cluster of novel resist-coating/developing and immersion-exposure equipment

Abstract

The demand for even denser semiconductor devices is driving efforts to reduce pattern dimensions in semiconductor lithography. It has been found that 193-nm immersion lithography technology can achieve smaller patterns without having to modify the infrastructure technology of existing state-of-the-art 193-nm dry lithography. This has made 193-nm immersion lithography a promising technology for next-generation mass production processes. It is now under full-scale development and is about to enter a commercial stage applicable to mass production.In 193-nm immersion lithography, the space between the optical projection system and silicon wafer is filled with liquid thereby immersing the resist film in de-ionized water during exposure. This generates a number of concerns, such as the penetration of moisture into the resist, the leaching of resist components into deionized water, and the presence of residual moisture, all of which can lead to defects that can affect post-processing. It has been reported; however, that rinse processing before and after exposure can be effective in reducing such defects [1]. Also, the trend toward finer patterns has resulted in large aspect ratios that can lead to pattern collapse, but the application of a surfactant has been found to ease this problem. Controlling the drying process after rinsing has also been found to reduce residue adhering to the resist.The stability of process data is considered to be a crucial factor in the adapting of 193-nm immersion lithography to mass production. In this report, we obtain long-term data on defects and critical dimension (CD), examine this data for process stability, and discuss the applicability of 193-nm immersion lithography to mass production.

19-nm critical dimension process using mask shift double exposure in ArF immersion

“…Therefore, it can be seen that the line CD can be reduced further. The general limit of the aspect ratio of ArF immersion PR is 3 24 . In the case of ArF immersion, it is common that the line CD cannot be patterned below 30 nm, and thus the minimum thickness of ArF immersion PR mass-produced to date is 900 Å 25 .…”

Recent performance results of Nikon immersion lithography tools

“…1 The S610C also shows excellent interfield CD uniformity as shown in Fig. 5 Similarly, the Tandem Stage can be used to calibrate the autofocus system frequently during wafer exchange to improve the focus accuracy of the tool.…”

“…Previously, defect stability results from the S609B showed low, stable defectivity over several months using developer-soluble topcoat. 1 The contact angle as the wafer enters the immersion nozzle is the advancing contact angle (ACA). If this contact angle becomes too large, air can easily enter the immersion fluid.…”