摘要:

For industrial application of an electron beam direct writing a single‐layer‐resist (SLR) process is more attractive than a multilayer‐resist process, because the SLR process is less expensive and provides a precise pattern transfer for 0.2‐μm large scale integration circuit fabrication. Three key factors for SLR process are (1) high acceleration voltage for clear latent image, (2) high‐contrast resist to attain a high‐aspect‐ratio pattern, and (3) rapid dissolving resist with little effect on the substrate. With 50‐kV acceleration voltage an aspect ratio of resist pattern of about 5 is obtainable using a chemically amplified resist. However, pattern collapse limits the maximum aspect ratio for smaller resist patterns. A positive‐tone resist (PSR) and negative‐tone resist (RE‐4200N) showed excellent characteristics for a SLR process with a 0.2‐μm feature size.  

ISSN:0734-211X    

DOI:10.1116/1.587566

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

A new interpretation of the acid generation process in novolak resin systems is reported. To investigate the acid generation process in chemically amplified resist, a novolak resin system with an acid generator (PAG) was employed. In order to analyze the acid generation process, the visible absorption characteristics from a conventional spectrophotometer, and nanosecond and millisecond pulse radiolysis systems, were analyzed. Form‐cresol novolak with triphenylsulfonium triflate, it was hypothesized that acid would be generated during exposure; however, it is asserted that a protonated intermediate was generated during exposure and that acid was generated during exposure, and more acid was formed during PEB. The yield of the acid during PEB, rather than that of the protonated intermediate during exposure, was strongly influenced by the presence of triphenylamine. A comparison of the experimental result form‐cresol novolak which contains PAG with that forp‐cresol novolak which also contains PAG indicates that the time range of acid generation may be dependent on the base resin system.

ISSN:0734-211X    

DOI:10.1116/1.587567

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Patterned, selective electroless deposition has been achieved using exposed and developed photoresists, produced with UV and e‐beam exposure sources, to create channels for constrained metal growth on ligating self‐assembled film surfaces. This process is attractive for the production of high‐resolution, etching‐resistant features for semiconductor integrated circuit (IC) fabrication, as well as for the fabrication of patterned metal lines for IC‐level and (PWB)‐level interconnects. Etched metal features with linewidths of 150 nm have been demonstrated.

ISSN:0734-211X    

DOI:10.1116/1.587568

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Two methods to measure acid diffusion in positive acid catalyzed resists are described. The first method employs a spectrophotometric titration to determine the acid concentration ([H+]) followed by measuring the ion conductivity (σ) of the resist film to determine the diffusion coefficient (D). This method allows the diffusion coefficient of acid in the resist to be determined at different temperatures ranging from room temperature to different post‐exposure bake (PEB) temperatures. The second method is based on the threshold acid density theory of image formation, which assumes that when a critical concentration of acid is reached, the developer solubility of the resist is changed. With this method, a constant level of acid can be followed at different PEB times and the diffusion coefficient determined. A comparison of the two methods to measure the acid diffusion coefficient will be made and the temperature dependence of diffusion for different types of organic acids will be presented. Based on a previously described reaction–diffusion model that predicts relative deblocking levels, evidence is presented for room temperature diffusion of acid to be a possible explanation for delay instability in positive deep ultraviolet resists.

ISSN:0734-211X    

DOI:10.1116/1.587569

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Molecular weight distribution effects of novolak resin‐based chemical amplification negative resist systems are investigated for electron‐beam lithography. The resist systems investigated consist of onium salts as an acid generator, a methoxymethyl melamine crosslinker, and a conventional/fractionated novolak resin matrix. Delineated patterns of both types of resist systems are compared to evaluate submicron‐scale resolution. The conventional novolak resin‐based system shows higher contrast than the fractionated one. High aspect ratio patterns are resolved for the conventional novolak‐based resist, whereas poor results are obtained for the fractionated resin‐based one on the submicron scale. Very thin films (30 nm) of both resist systems are delineated with a finely focused electron beam (diameter: approximately 2 nm at 5 kV) from a scanning electron microscope. Nanometer‐scale edge roughness (nanoedge roughness) is observed for the conventional novolak resin‐based resist. On the contrary, the degree of nanoedge roughness is greatly reduced for the fractionated one.

ISSN:0734-211X    

DOI:10.1116/1.587570

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

This article presents the results of the experimental and modeling study of a positive tone, chemically amplified photoresist, in application to x‐ray lithography. Spectrophotometric titration, Fourier transform infrared spectroscopy (FTIR), and development rate monitor data were acquired and used as inputs for the modeling of the processes and pattern simulations. The exposure model assumes monomolecular decomposition upon radiation and corresponds to Dill’s model for a nonbleaching photoactive compound. The post‐exposure bake (PEB) model is based on formal kinetic equations which include a term for photoacid loss (or side reactions) during the post‐exposure bake process in a generalized way. The effective kinetic order of the photoacid loss reaction is derived from the FTIR absorbance data obtained for different PEB times and exposure doses. For patterned exposures, a diffusion term for the local photoacid concentration is included. The photoacid and tert‐butoxycarbonyloxystyrene concentration profile changes with PEB time have been simulated for a 0.25 μm line and spaces pattern. It is shown that a nonlinear PEB photoacid reaction kinetics, rather than the photoacid diffusion, dominates the linewidth decrease during PEB for the photoresist studied.

ISSN:0734-211X    

DOI:10.1116/1.587571

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

A high‐speed chemically amplified positive resist based on poly(p‐hydroxystyrene) has been developed for x‐ray lithography. This resist, CANI (meaning chemically amplified resist) by Nippon Telegraph and Telephone Corporation, has a sensitivity of 50–70 mJ/cm2to soft x rays while maintaining sub‐0.25‐μm resolution and a rather large dose margin of 34%–40%. Another advantage of CANI is that the theoretical weight loss from the removal oft‐butyl protecting groups by chemical amplification reactions is less than 4 wt %. This leads to little volume shrinkage at uv cure and reactive ion etching processes, and thus promises good controllability of pattern feature sizes between lithography and subsequent plasma etching processes.

ISSN:0734-211X    

DOI:10.1116/1.587572

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

Plasma‐polymerized resist films (PPMS) based on methylsilane have high sensitivity to short wavelength radiation. The photoinduced oxidation of PPMS films exposed in air forms siloxane network material, allowing dry development by selective rapid etching of the unexposed regions upon treatment with chlorine based plasmas. Negative‐tone patterns of oxidized methylsilane thus formed can be transferred through an underlying organic planarizing layer (0.7 μm) with excellent selectivity (≳100) to give high resolution patterns. This provides a versatile, dry photolithographic process usable with current exposure and etching tools that can be integrated into future cluster tool technologies. This article details the process tolerances and lithographic performance of PPMS under 248 nm exposure. Structures as small as 0.2 μm were printed with exposures ranging from 50 to 200 m cm−2on a GCA XLS DUV stepper. Promising results are also obtained over topography.

ISSN:0734-211X    

DOI:10.1116/1.587573

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

A positive‐tone surface imaging process using wet silylation of the commercial photoresist AZ 5214ETMis presented; it is seen as a practical method to extend optical lithography down to 0.25 μm and to increase significantly the resolution limits of available steppers, without adding appreciable process complexity and cost. A comparative study is done usingH‐line,I‐line, and deep ultraviolet at 248 nm lithography on different steppers. The resolution achieved corresponds to akfactor of 0.4 [i.e., 0.4λ/(numerical aperture)]. The importance of the dry‐development step and the thermal effects associated with the heating of the wafer during etching are discussed.  

ISSN:0734-211X    

DOI:10.1116/1.587574

出版商:American Vacuum Society    

年代:1994

数据来源: AIP

摘要:

This paper describes the development of a surface‐imaging process for a positive‐tone silylated, dry‐developed bilayer resist which has 0.2 μm resolution and an aspect ratio of 4.5 using deep‐UV (248 nm) exposure. The many processing variables such as thermal treatment parameters, silylation conditions, and etching conditions were examined to determine their effects on lithographic performance in terms of resolution, feature size linearity, focus latitude, and sensitivity. Critical to the success of the process are: the bilayer structure which restricts diffusion of the Si, the use of a disilane reagent to increase the Si content of the masking layer, limiting migration of photogenerated acid by the appropriate choice of softbake and post‐exposure bake temperatures, initial etching with an Ar/Cl2mixture to remove the thin layer of silylated resist in the exposed areas, and employing CO2instead of O2as the etching gas to eliminate lateral etching of the features. With this process we have obtained good critical dimension linearity down to 0.25 μm for bright‐field and dark‐field lines and spaces as well as isolated lines and isolated spaces. The dose required is ∼75 mJ/cm2and the dose latitude is ±6%. Focus latitude is at least ±0.4 μm. We also observe no environmental effects on sensitivity or resolution.

ISSN:0734-211X    

DOI:10.1116/1.587575

出版商:American Vacuum Society    

年代:1994

数据来源: AIP