Top coat less resist process development for contact layer of 40nm node logic devices

Abstract

ArF immersion lithography has been introduced in mass production of 55nm node devices and beyond as the post ArF dry lithography. Due to the existence of water between the resist film and lens, we have many concerns such as leaching of PAG and quencher from resist film into immersion water, resist film swelling by water, keeping water in the immersion hood to avoid water droplets coming in contact with the wafer, and so on. We have applied to the ArF dry resist process an immersion topcoat (TC) process in order to ensure the hydrophobic property as well as one for protecting the surface. We investigate the TC-less resist process with an aim to improve CoO, the yield and productivity in mass production of immersion lithography. In this paper, we will report TC-less resist process development for the contact layer of 40nm node logic devices. It is important to control the resist surface condition to reduce pattern defects, in particular in the case of the contact layer. We evaluated defectivity and lithography performance of TC-less resist with changing hydrophobicity before and after development. Hydrophobicity of TC-less resist was controlled by changing additives with TC functions introduced into conventional ArF dry resist. However, the hydrophobicity control was not sufficient to reduce the number of Blob defects compared with the TC process. Therefore, we introduced Advanced Defect Reduction (ADR) rinse [1,2], which was a new developer rinse technique that is effective against hydrophobic surfaces. We have realized Blob defect reduction by hydrophobicity control and ADR rinse. Furthermore, we will report device performance, yield, and immersion defect data at 40nm node logic devices with TC-less resist process.

Dissolution kinetics of poly(4-hydroxystyrene) with different molecular weight distributions in alkaline aqueous solution

“…The transient formation of swelling layer is considered to play an important role for the defect formation. [28][29][30] This study revealed that the tendency of dissolution depends on both the molecular weight and molecular weight dispersion of the polymer. Dissolution occurs through the swelling of the polymer bulk and the diffusion of polymer chains into the solution bulk.…”

Relationship between surface free energy and development process (swelling and dissolution kinetics) of poly(4-hydroxystyrene) film in water and 2.38 wt% tetramethylammonium hydroxide aqueous solution

“…Resist swelling was suggested as one of the causes of defect generation. [17][18][19] In the development of EUV resists, the dissolution kinetics was investigated by high-speed atomic force microscopy. It was revealed by in situ observation that the thickness of the exposed area was doubled at most during development.…”

Analysis of dissolution kinetics of narrow polydispersity poly(4-hydroxystyrene) in alkaline aqueous solution using machine learning

“…5,6) The clarification of the development processes is a key to the improvement of resist performance. [6][7][8][9] In particular, understanding of the dissolution kinetics of acidic polymers such as PHS is important, because they are the essential core for the dissolution during development.…”