摘要:

Oxygen‐based plasmas commonly used in resist stripping and multilayer resist patterning are contrasted to highlight the differences involved in these applications. Mechanisms for polymer etching are reviewed, with particular emphasis on silicon‐containing resists proposed for bilayer lithography. While silicon‐containing materials offer a simpler process than trilayer schemes for improving lithographic resolution, considerable differences in etch behavior among these materials have been observed. Further characterization and fundamental understanding are required before widespread acceptance of silicon‐containing resists is achieved.

ISSN:0734-211X    

DOI:10.1116/1.584440

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

Spatial profiles of CF2concentration in C2F6rf plasma are measured by the laser‐induced fluorescence method. The observed profiles are explained by the generation and recombination reaction mechanisms of CF2. It is found that the deposition rate of fluorocarbon polymer on SiO2film is proportional to [CF2]n;n=2.5–3.0, whereas the etch rate of SiO2is proportional to [CF2]. Both the etching and the deposition reactions proceed at the same time. Based on these observations, reaction mechanisms for fluorocarbon polymer deposition and SiO2etching are analyzed.

ISSN:0734-211X    

DOI:10.1116/1.584438

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

Ar+ions of 0.5 to 2 keV from a broad‐beam Kaufman ion source have been used to induce chemical etching of Si by SF6effusing from a gas dispensing ring placed near the Si surface. Etch rates have been measured as a function of sample temperature, SF6flux, and ion energy. As the Si temperature is reduced below 120 K the Si yield per Ar+ion rises to reach a maximum enhancement of about 8–10 just below 100 K, compared to pure physical sputtering. The results suggest that the dominant effect of the sample temperature is to control the fluorine supply via the evaporation rate of physisorbed SF6molecules. This etching process has been applied to produce micron‐sized, blazed gratings in Si, using Al as a hard mask. Blaze angles up to 70° have been produced by tilting the sample with respect to the ion beam.

ISSN:0734-211X    

DOI:10.1116/1.584439

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

The process parameter space for fluorocarbon plasmas (C2F6/CHF3and CF4/CHF3, with and without He) which are used to etch SiO2has been examined with a Lam Research Autoetch 580 parallel plate, single‐wafer etching system by response‐surface methodology. The response or behavior of the plasmas differs very significantly with reactor pressure, etch gas mixture, and He addition. In particular, substantially higher SiO2etch rates are obtained with C2F6/CHF3plasmas than with CF4/CHF3plasmas at an equivalent radio frequency power density for similar gas flow rates at significantly different reactor pressures: ∼2500 Å/min at ∼400 mTorr with C2F6/CHF3mixtures and ∼750 Å/min at ∼1500 mTorr with CF4/CHF3mixtures. Upon addition of He to the plasmas, the SiO2etch rate maximum for the C2F6‐based plasma shifts to ∼800 mTorr and declines to ∼2000 Å/min, while that for the CF4‐based plasma remains near 1400 mTorr and increases to ∼1000 Å/min. Whereas the addition of He sharply degrades the etching uniformity with C2F6/CHF3mixtures, it has no apparent effect on the etching uniformity with CF4/CHF3mixtures, which is high with or without the addition of He over the parameter space which was explored. For the C2F6/CHF3plasma, the etch selectivity to silicon is highest at 700–1100 mTorr, while for the CF4/CHF3plasma the selectivity is highest at 1100–1500 mTorr. Although addition of He substantially improves the selectivity with the CF4/CHF3plasmas, it has no effect on selectivity with the C2F6/CHF3plasma. These detailed characterizations of process parameter space have led to a uniform and selective SiO2sidewall spacer etching process which may be readily extended to other SiO2etching processes with this equipment and these gas mixtures.

ISSN:0734-211X    

DOI:10.1116/1.584441

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

InsituFourier transform infrared (FTIR) spectroscopy has been utilized to detect gas‐phase product species resulting from the dry etching of aluminum and heavily dopedn‐type polycrystalline silicon (n+poly‐Si) in Cl2. The products of aluminum etching in Cl2were investigated in the presence and absence of a plasma. With the plasma off, Al2Cl6was the only infrared‐active etch product detected at both low (50 °C) and high (>120 °C) sample temperatures. With the discharge on, the spectrum was more complex, indicating partial fragmentation of the dimer etch product in the plasma forming AlCl3and, perhaps, AlCl. Silicon tetrachloride was the only infrared‐absorbing product detected during the Cl2plasma etching ofn+poly‐Si. Unsaturated silicon chlorides (SiClx,x=1–3) were not present at detectable levels. These results are compared with those of ultrahigh vacuum (UHV) beam studies; in comparing UHV results with those obtained in a processing plasma, allowances must be made for the considerable difference in pressure, and therefore, in species’ fluxes in these two experimental environments. Unlike UHV studies,insituFTIR measurements permit detection of etch products under typical processing conditions. When interpreting the results, however, the possibility that the products leaving the sample surface react further upon entering the plasma must be considered.

ISSN:0734-211X    

DOI:10.1116/1.584442

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

Reactive ion etching of GaAs and AlGaAs has been performed in a BCl3–Ar discharge. Etching properties have been studied as functions of BCl3percentage (0%–100%), total pressure (2.5–30.0 mTorr), and power density (0.06–0.22 W/cm2). At low pressures (2.5–12.5 mTorr) and intermediate BCl3percentages (25%–75%), profiles exhibiting a high degree of anisotropy are achieved. Under anisotropic conditions, etch rates are about 0.05–0.1 μm/min (at power density of 0.22 W/cm2), somewhat lower than for other chlorine‐containing gases. Conditions for etching GaAs and AlGaAs at equal rates have been determined. There is a small lag time between ignition of the glow discharge and the start of etching. The relative concentration of Cl atoms in the plasma, as measured by optical emission actinometry, correlates well with the etch rate for various operating parameters.

ISSN:0734-211X    

DOI:10.1116/1.584443

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

For investigating the fundamental characteristics and resolution limit of patterns replicated with synchrotron orbital radiation (SOR), a computer simulation program, synchrotron orbital radiation lithography simulation system (sorsis) has been developed and resulting resist pattern profiles have been analyzed in detail. Insorsis, Fresnel integrals are performed by a new model based on introducing the SOR wavelength distribution, mask contrast, and phase difference into calculations. Positive‐type resist replication pattern profiles are calculated to evaluate pattern characteristics and are compared with experimental results. These results derive a resolution limit evaluation method, representing the equationW=ε(Gλp/2)1/2.3, whereWis the minimum linewidth,Gthe proximity gap, λpthe wavelength peak, and ε the parameter mainly determined by resist characteristics and x‐ray mask absorber thickness. In this way, optimum conditions for precise pattern replication and accurate pattern profile control can be realized easily.

ISSN:0734-211X    

DOI:10.1116/1.584694

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

A new technique for submicron optical lithography is reported. Water‐soluble contrast enhancing material fori‐line exposure prevented the undercut profile of negative photoresist and attained high‐aspect‐ratio rectangular patterns. New portable conformable maskingi‐line lithography using the water‐soluble contrast enhancing material could successfully fabricate a two‐layer resist composed of negative photoresist RU‐1100N as a top layer and positive deep ultraviolet resist poly(dimethylglutarimide) as a bottom layer.

ISSN:0734-211X    

DOI:10.1116/1.584695

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

An experimental study of the etching of Si with SF6/halogen and halogen mixtures has been performed in a multipolar electron cyclotron resonance plasma with independent rf biasing. At constant total pressures and at a constant ion energy (75 eV), the anisotropy and the etch rate of silicon have been measured as a function of halogen percentages in the mixtures. The results are explained in terms of a recently developed diffusion model for plasma etching. Fluorine, chlorine, and bromine mixtures, contrary to iodine, etch Si, and SiO2. The bromine and chlorine adsorption on silicon appears to be monolayerlike, whereas fluorine adsorption is clearly of the multilayer type. Experimental results on etching anisotropy and selectivity with respect to SiO2are also analyzed with emphasis on the peculiar behavior of bromine.

ISSN:0734-211X    

DOI:10.1116/1.584696

出版商:American Vacuum Society    

年代:1989

数据来源: AIP

摘要:

Poly(methacrylic anhydride) (PMAH) is a positive resist for use in electron beam (e‐beam) lithography. It is derived by heating coatings of the precursor polymer, poly(tert‐butyl methacrylate) or PtBMA, on the wafer. Crosslinks are introduced during the thermal conversion. The sensitivity and line profiles of PMAH e‐beam images are significantly affected by the synthesis route, the pre‐exposure processing, and the development method. Development with organic solvents can swell and soften the resist, especially in areas that received some exposure to radiation. This causes the walls of the image to expand or flow into the image cavity, thereby limiting the sensitivity at which high resolution can be achieved. However, the use of a new, nonswelling, basic developer gives PMAH a sensitivity of 2.5 μC/cm2with better than 0.5 μm resolution.

ISSN:0734-211X    

DOI:10.1116/1.584697

出版商:American Vacuum Society    

年代:1989

数据来源: AIP