Takuya Hagiwara

Immersion-Specific Defects of High-Receding-Angle Topcoat

Dynamic receding contact angle (RCA) is a well-known parameter for estimating the degree of immersion-specific defects that have mainly circular and bridge shapes. In general, these defects decrease in number with increasing RCA of the topcoat (TC). However, we found the occurrence of circular defects despite using the TC with a large RCA. In this study, we analyzed the relationship between the physical properties of TC to reduce the number of defects. The result shows that the number of defects depends not only on a large RCA but also on a small amount of water uptake of TC. To understand well the degree of defects, the effective hysteresis (EH) is defined in terms of the RCA, the advancing contact angle (ACA) and the water absorption of TC. EH will be a useful way of explaining the circular defects. The characteristics of the defects are also discussed with a focus on the structure of the polymer attached to water.

Double Patterning Using Multilayer Hard Mask Process with Perhydropolysilazane

A new technology called the double patterning (DP) process with ArF immersion lithography is one of the candidate fabrication technologies for 32-nm-node devices. Over the past few years, many studies have been conducted on techniques of the DP process. Among these technologies, the double Si hard mask (HM) process is thought to be the most applicable technology from the viewpoint of high technical applicability to 32-nm-node device fabrication. However, this process has a disadvantage in terms of cost performance compared with other DP technologies since these HMs are formed by the chemical vacuum deposition (CVD) method. In this study, we examined the DP process using a dual spin-on Si-containing layer without using the CVD method to improve process cost and process applicability. Perhydropolysilazane (PSZ) was used as one of the middle layers (MLs). PSZ changes to SiO2 through reaction with water by the catalytic action of amine in the baking step. Using PSZ and Si-BARC as MLs, we succeeded in fabricating a fine pattern by this novel DP technique. In this paper, the issues and countermeasures of the double HM technique using spin-on Si-containing layers will be reported.

Improvements of adhesion and hydrophobicity of wafer bevel in water immersion lithography

In this study, we focus on the controllability of a wafer bevel from adhesion and hydrophobicity viewpoints in order to solve the problems of film peeling and microdroplet formation around wafer bevels, which result in pattern defects. Hexamethyldisilazane (HMDS) treatment is a common solution to these problems. We examine a novel wafer bevel treatment utilizing silane coupling agents (SCAs) for obtaining high adhesion and hydrophobicity. SCAs comprise trimethoxysilanol and organic functional groups. These groups react with inorganic substrates and films just over the surface subjected to a novel chemical treatment (NCT), respectively. Several organic functional groups both with and without fluorine are examined. The hydrophobicity is estimated from the static and receding contact angles of water. The adhesion strength is measured from the stress required for pulling the topcoat film away from the substrate subjected to the NCT. The coating performance of chemicals on the surface by the NCT and the aging stability of the formulated solution of the SCAs are examined for optimizing the composition of the NCT solution. Further, we verify the film peeling behavior and water leakage in wafers having a topcoat, ArF resist, and bottom antireflective coating (BARC) using a quasi-immersion exposure stage.

Double patterning using dual spin-on Si containing layers with multilayer hard mask process

A new technology called the double patterning (DP) process with ArF immersion lithography is one of the candidate fabrication technologies for 32 nm-node devices. Over the past few years, many studies have been conducted on techniques for the DP process. Among these technologies, we thought that the double Si hard mask (HM) process is the most applicable technology from the viewpoint of high technical applicability to 32 nm-node device fabrication. However, this process has a disadvantage in the cost performance compared with other DP technologies since these HMs are formed by the chemical vacuum deposition (CVD) method. In this paper, we studied the DP process using a dual spin-on Si containing layer without using the CVD method to improve process cost and process applicability. Perhydropolysilazane (PSZ) was used as one of the middle layers (MLs). PSZ changes to SiO2 through the reaction with water by the catalytic action of amine in the baking step. Using PSZ and Si-BARC as MLs, we succeeded in making a fine pattern by this novel DP technique. In this paper, the issues and countermeasures of the double HM technique using spin-on Si containing layers will be reported.

Estimation of resist blur by overlay measurement

A method to estimate a magnitude of resist blur by overlay measurement with a special mark. Because of utilization of optical measurement, line-end-shortening (LES) can be measured with good repeatability, resulting in accurate estimation of a magnitude of resist blur. This method is very useful to estimate resist blur in an advanced lithography era.