摘要:

Electron‐beam exposure and computer simulation are used to characterize the performance of Ge0.1Se0.9inorganic resist and examine the fundamental mechanisms of resist action. A first‐order model based on the energy density of electrons deposited in the active region along the interface of the sensitized layer and the resist is developed. Resist sensitivity as a function of sensitized‐layer thickness and accelerating voltage are calculated with the Monte Carlo method and compared with experimental results. Special test patterns including multiscanning are designed to explore lateral diffusion of silver in the sensitized layer and proximity effect due to backscattering. With Ge0.1Se0.9resist and e‐beam direct writing sub‐half‐micrometer working lithography can be achieved on silicon substrate at incident doses comparable with that needed for polymethylmethacrylate (PMMA) polymer resists.

ISSN:0734-211X    

DOI:10.1116/1.583342

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

Irradiation of poly(methylmethacrylate) film, PMMA, with e‐beam, H+, x ray, and deep UV creates reactive centers which combine with acrylic acid vapor to form graft and/or block copolymers with solubilities different from that of PMMA. Dissolution rate studies of modified PMMA using a variety of solvents have revealed that while toluene forms good negative‐tone images, it develops too slowly, and that a mixture of methylisobutylketone and isopropanol is not selective enough to give images with good contrast. Consideration of the solubility parameters of pure PMMA and pure poly(acrylic acid) (PAA) indicates that organic esters such as methylformate (MF), ethylacetate (EA), and a commercially available mixture (Dupont Co.) of dimethylsuccinate, dimethylglutarate, and dimethyladipate (DBE) could be useful development solvents for the samples under discussion. The data obtained reveal that toluene gives the best image, but also reveal that the dissolution rates decrease as the development fronts proceed into the body of the film.

ISSN:0734-211X    

DOI:10.1116/1.583343

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

A new intermediate layer material, silyl ether of novolak (Si–novolak), and a new Si containing resist, silyl ether of a naphthoquinone diazide ester of novolak, Si–LMR (low molecular weight resist), have been developed for trilevel and bilevel resist systems, respectively. Si–novolak has high O2‐reactive ion etching (RIE) resistivity and high solubility in nonpolar solvents, such as xylene and chlorobenzene, which cause no damage to the film of novolak. When novolak and Si–novolak are employed as the bottom and intermediate layer materials, respectively, both layers can be formed by successive coatings without baking the bottom layer. Si–novolak is easily hardened by deep UV light. Therefore, a trilevel resist can be formed by one deep UV blanket exposure and one baking step, besides coating steps. The triresist system, LMR/Si–novolak/novolak, provides 0.5 μm resist patterns with steep profiles and good line control over topography. Si–LMR is a negative deep UV resist and its sensitivity is 100 mJ/cm2. The O2‐RIE selectivity of Si–LMR to AZ‐2400 is larger than 15. The bilevel resist system, Si–LMR/AZ‐2400, clearly generates 0.5‐μm‐wide patterns with an aspect ratio of 4.

ISSN:0734-211X    

DOI:10.1116/1.583344

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

We propose a new photoresist (MSNR: methacrylated silicone‐based negative resist) for high resolution bilayer resist systems. This photoresist shows high sensitivity to near‐UV light (350–450 nm),D0.5n=40 mJ/cm2, and excellent resistance to reactive ion etching with oxygen. A submicron (0.5 μm) pattern with a high aspect ratio can be easily fabricated with MSNR/AZ bilayer resist systems using near‐UV lithography.

ISSN:0734-211X    

DOI:10.1116/1.583345

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

Over the past several years a class of silver‐doped GeSexmaterials has received attention as a high gamma, negative resist. The columnar structure of the GeSexfilms is believed to be linked to some of the lithographic properties of the resist. However, the mechanism of Ag incorporation is not well understood. In this paper we report secondary ion mass spectroscopy (SIMS) observations of the Ag migration in GeSe2films. Furthermore, we have found evidence for a fast Ag diffusion effect in GeSe2. These findings are consistent with a columnar GeSe2structure. The Ag concentration depth profile in 3000‐ and 6000‐Å‐thick films of GeSe2on substrates consisting of 300 Å of Ta on silicon wafers has been studied by SIMS. An O+2primary beam was used in the SIMS analysis, with the bombardment energy reduced to 3 keV to minimize possible beam‐induced effects and to increase the depth resolution. The Ag2Se/GeSe2resist was exposed by an unfiltered mercury arc source and received doses ranging from 0 to 2 J/cm2. The unreacted Ag2Se was stripped prior to the SIMS analysis. The Ag incorporation was found to increase rapidly with exposure first, and then saturate about 1 J/cm2. But instead of Ag being uniformly distributed through the GeSe2films, its concentration peaks both near the top surface and at the substrate interface. The anomalous Ag peak at the substrate interface indicates that Ag diffuses far beyond the penetration depth of the radiation and presumably piles up in front of the Ta diffusion barrier. Moreover, with the same exposure, the anomalous Ag peaks are identical in both the 3000‐ and 6000‐Å‐thick films. These results are consistent with the model of Ag diffusion through the columnar structure of GeSe2, an extremely fast path in regions between the columns extending through the film, and a slower diffusion component in the denser regions within the columns.

ISSN:0734-211X    

DOI:10.1116/1.583346

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

The relationship between etching characteristics and silicon content for organosilicon polymers has been studied. Under oxygen reactive ion etching (O2‐RIE) conditions, the etching rate for the polymers became constant after an initial rapid decrease. An etching kinetic study was carried out to account for this behavior. It is confirmed from electron spectroscopy for chemical analysis (ESCA) data that a protective layer, which has high resistance against O2‐RIE, is formed on the polymer surface and that most silicon atoms exist in the form of SiO2at the protective layer surface. The etching rate for the polymers in a steady state is inversely proportional to the silicon content. The etching rate for quartz glass is in good agreement with the value extrapolated from this relationship. These results suggest that the rate determining step in the etching process is the sputtering of SiO2formed by the polymer oxidation. Furthermore, for a polymer with a lower silicon content than a threshold value, the protective layer is porous, so that the underlying polymer is attacked by radical species during O2‐RIE. The threshold silicon content is about 0.15 g/cm3.

ISSN:0734-211X    

DOI:10.1116/1.583347

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

The novolak‐based resist image is thoroughly hardened by baking with a conformable mold which is formed by spin coating polymethylmethacrylate (PMMA) over the novolak image. Therefore, instead of a deep‐UV hardening exposure or a plasma hardening step followed with a high temperature bake, this hardening process consists of a PMMA coating followed with a high temperature bake. Experimental results show that hardening took place throughout the bulk of the resist. The resist profile remains intact after a 200 °C bake and a second novolak resist image can be delineated on top of the hardened image without any mutual interaction, whereas conventional deep‐UV or plasma hardening technique can only harden the resist surface layer. Large features hardened with these conventional techniques tend to deform. Recent results showed stability of resist profile for baking temperature up to at least 500  °C in a nitrogen flushed furnace. The lateral dimension change of the resist image after resist hardening using a conformable mold (RHCM) and 500 °C bake was shown to be less than 0.05 μm.

ISSN:0734-211X    

DOI:10.1116/1.583348

出版商:American Vacuum Society    

年代:1986

数据来源: AIP

摘要:

An attempt was made to improve the sensitivity and heat resistance of positive photoresist applicable to very large‐scale integrated (VLSI) semiconductor processing. It was found out that, in general, when the lithographic sensitivity of resist was made higher, film thickness retention and heat resistance were lowered. A study was made on how to raise sensitivity without decrease in film thickness retention and heat resistance. It was necessary to design a new type of novolac resin that has a molecular structure and a molecular weight different from the existing materials. Many kinds of cresol‐formaldehyde type novolac resins were synthesized and evaluated. Such items as the isomeric structure of cresol, the position of the methylene bond, and the influence of molecular weight were investigated. As a result of the optimization of these items, a number of different resist materials that exhibit improved characteristics in sensitivity, film thickness retention, and/or heat resistance were obtained. It is also remarkable that the introduction of the new polymer design enabled to make the allowance of the operating conditions much wider at various points of resist work, including prebaking temperature, light exposure time, developing time, and developing temperature, compared to the present commercially available products. This new material not only makes it possible to raise the throughput of the stepper exposure machine and developing machine, but the wider allowance of processing conditions assures higher yield of the circuits.

ISSN:0734-211X    

DOI:10.1116/1.583349

出版商:American Vacuum Society    

年代:1986

数据来源: AIP