Sub 0.1-/spl mu/m Pattern Fabrication Using a 193-nm TSI Process

Abstract

1. I n t r o d u c t i o n ArF excimer laser lithography is expected to produce the highest resolution in optical lithography, a n d its applicabhty to 0.13 pm device fabrication has been sufficiently demonstratedl*Z. For the fabrication of sub 0.10-pm devices, it w a s believed that the mix and match process using optical lithography and other types of lithography would be indispensable. One reason for this is the difficulty in fabricating contact holes with a larger process margin. The top surface imaging (TSI) process, which uses a silylated resist, is one approach for 193 nm lithography t h a t is currently being targeted for the sub-0.1-pm design rule. We demonstrate that TSI can be used to produce sub-0.1-pm device patterns. This paper presents a n overview of 0.1-pm pattern fabrication. We discuss the process margins for binary, isolated line, isolated space, and contact hole patterns. 2. E x p e r i m e n t We used the chemically amplified resist, NTS-4, from Sumitomo Chemical Co., Ltd. Silylation was done by using dimethylsilyldimethylamine (DMSDMA) in the vapor phase. And then, a silylated resist was developed in 0 2 S 0 ? plasma. The exposure tool was a n IS1 stepper (1OX reduction and 0.6-NA). 3. R e s u l t s and D i s c u s s i o n Good pattern profiles were obtained, for the 0.09-pm contact hole, 0.04-pn isolated line, and 0.06-pm space (Fig. 1). High sensitivities were achieved, 20 mJ/cm’ for the contact hole, 5 mJ/cm‘ for t he isolated line, and 7 mJ/cm‘ for the isolated space. The TSI process produces excellent lithographic patterns, for the isolated patterns. We etched a 1.0-pm thick Si02 film using a resist pattern as a mask. The vertical contact hole pattern (aspect ratio 12) in Fig. 2 (a) was obtained. After dry etching, the resist was successfully removed by O2 ashing without residue, Fig. 2 (b). An exposure latitude of +/10% was obtained with a 0.10-pm contact hole (Fig. 3(a)). The focus latitude was narrow for the Cr mask(Fig. 3(b)(c)). However, we can obtain a sufficient depth of focus (DOF) by using a n attenuated phase-shifting-mask (PSICI). This result is suitable for dynamic planarized substrates such as CMP process. Next, we evaluated the line and space binary pattern. We resolved the 0.085 pm line and space pattern, using a n alternative phase shifting mask (Fig. 4). We obtained a 0.7-pm DOF for 0.09 pm line a n d space pattern, using a n alternative phase shifting mask (Fig. 5). It is necessary to use a n alternative phase shifting mask for sub 0.10 pm line and space binary pattern fabrication. 4. S u m m a r y We have developed a 193-nm TSI process for the sub 0.10 pm device rule. We demonstrated that TSI is the advantages for isolated pattern fabrication. And w e demonstrated sub-0.10-pm line and space binary pattern fabrication. Sub-0.10-pm patterns were shown to produce by using the TSI process for 193 nm lithography. This work was performed under the management of ASET in MITT’S R&D program supported by the New Energy and Industrial Technology Development Organization (NEDO). Reference 1. M. Takahashi e t al., Proc. 3333, in Press (1998) 2. S . Kishimura e t al., Proc. 3334, in press (1998) First, we discuss the isolated patterns.