摘要:

Bilayer photoresist schemes have the potential of satisfying the many stringent demands associated with the lithographic exposure step. Because the film thickness for this process is quite small, the aspect ratios are increased relative to single layer lithography and hence increased resolution may be obtained. The planarizing layer used in bilayer schemes can also be dyed to avoid reflectivity problems. In this paper the development of a resist for use as the imaging layer in a bilayer resist scheme incorporating oxygen reactive ion etch for image transfer is described. The resist chemistry is based on the coupling reaction(s) of cyclic polyfunctional silanols. The resist is composed of a cyclic silanol, an acid photogenerator, and a phenolic resin. The catalytic nature of the chemistry involved in the resist resulted in high sensitivity during the exposure process. The observed contrast was greater than four for several of the formulations due in part to the unique ‘‘bimodal’’ characteristics of this resist. With sufficient silanol content, high etch resistance was observed and bilayer resist methodology was carried out without loss of film thickness in the exposed regions. Submicron resolution was demonstrated.

ISSN:0734-211X    

DOI:10.1116/1.585350

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Thin film interference plays a destructive role in optical photolithography in two regards. (1) Large linewidth variations can occur from tiny changes in the thickness of resist or underlying thin films. (2) Asymmetric flow of resist over alignment mark topography can cause optical fringes which result in poor alignment signal profiles. In this paper, a new approach is described which can address both of these issues. A thin, low index, transparent film analogous to a lens antireflector (AR) coat is placed on top of the photoresist film before exposure. The ideal top antireflector (TAR) film would have thicknessT=λ/(4n’) andn’=(n)1/2wherenandn’are the refractive indices of resist and TAR, respectively. Experimental results are presented which show how various TAR layers can improve linewidth control and reduce notching as lines are patterned over topographic steps. In addition, simulations are presented which demonstrate how a TAR layer can improve the alignment signal, for certain types of alignment systems. The TAR process has great potential for high volume, economical semiconductor manufacturing.

ISSN:0734-211X    

DOI:10.1116/1.585351

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

This paper presents the results ofinsituellipsometry of x‐ray photoresists during development. PMMA was used to verify the results of previous studies and confirm the validity of the technique and the theoretical models. The technique was then applied to a negative chemically amplified photoresist Microposit XP‐90104C (Shipley). Because the chemically amplified resist uses an aqueous‐base developer (instead of the alcohol solvents such as in the PMMA system),insituellipsometry was employed to test the assumption that the resist does not swell during development. No appreciable swelling of exposed XP‐90104C was observed in MF‐322 developer for temperatures below 35 °C. At 40 °C, the onset of swelling was detected. The process of dissolution measured by ellipsometry departed slightly from a theoretical model of uniform film dissolution with an abrupt resist‐developer interface. Scanning electron microscopy (SEM) images of 0.3 μm lines printed with XP‐90104C indicate that surface roughening of the resist may account for the discrepancy of the experimental data from the uniform dissolution model.

ISSN:0734-211X    

DOI:10.1116/1.585815

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Electrically conducting polyaniline is found to be suitable for several lithographic applications. Because the polyaniline is not significantly soluble in the conducting state, the material has generally been processed by first applying the soluble, nonconducting version of the material, and in a second step externally doping the polymer film with aqueous acids. We have eliminated the need for this type of external doping by developing methods of inducing the doping in a dry fashioninsituin the polymer. This is accomplished by incorporating onium salts or amine triflate salts in the polyaniline which decompose upon radiation or thermal treatment, respectively, to generate the active dopant species, i.e., protonic acids. The use of theseinsitudopants simplifies the processing of the conducting polyaniline and makes the material more convenient for lithographic applications. With the use of onium salts, the polyaniline is made into a high resolution negative conducting resist. 0.25 μm conducting lines have been patterned with e‐beam radiation. Polyaniline is found to be an effective discharge layer for e‐beam lithography and a removable discharge layer for the high resolution inspection and dimensional measurements of x‐ray and optical masks by scanning electron microscopy (SEM). In addition, the polyaniline can be used for both electrolytic and electroless‐type metallization processes.

ISSN:0734-211X    

DOI:10.1116/1.585816

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Silylation processes have previously been applied to optical lithography to overcome deleterious substrate effects and to achieve smaller linewidths. We have applied silylation to focused ion‐beam (FIB) lithography, thereby eliminating the need for exposure throughout the entire resist thickness. This approach permits the use of Ga+ions which have a limited range in the resist but are available from high brightness sources. Thus FIB lithography writing speed can be dramatically improved. Sensitivity of 8×1011ions/cm2was found with 30‐keV Ga+using SAL 601 resist, and linewidths below 100 nm have been demonstrated.

ISSN:0734-211X    

DOI:10.1116/1.585817

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

A novel silicon‐containing chemical amplified resist has been developed for a shifter layer of phase‐shifting masks. The resist is composed of an alkaline‐soluble silicone polymer and onium salt as an acid generator. The base polymer has a ladder structure and contains a methyl group as a side group and ethoxy and hydroxy groups as an end group. Shifter patterns were directly fabricated on mask substrates by electron‐beam exposure and development of the new resist. Improved resolution using ani‐line stepper can be achieved with the phase‐shifting mask having the new silicon‐containing resist shifter.

ISSN:0734-211X    

DOI:10.1116/1.585818

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

New photoresist technologies yielding higher resist sensitivities together with the greater photon energies inherent in x‐ray lithography put lithography systems closer and closer to the shot noise limit. Thus there is a need to address the effects of shot noise on resist exposure. We will present the description of a stochastic model, and its implementation in a simulator, which emulates the exposure process by effecting what amounts to a photon‐by‐photon treatment of the problem, thereby taking into account the effects of shot noise. The model starts with an aerial image, computed using a deterministic model based on Fresnel diffraction, interprets it as the probability density function (pdf) for the distribution of the photons. The stochasticity of the process is taken into account by randomly generating a finite number of events (photons) whose distribution follows the pdf. The penetration depths are stochastically predicted according to the appropriate distribution. At the point predicted, the incident energy is redistributed according to a point spread function or a full Monte Carlo method. The superposition of all of the photons provides us with the latent image. The dissolution process is then modeled using a stochastic cell dissolution model. We will present results of practical importance for chemically amplified resist systems and correlate the results with observations made in the laboratory.

ISSN:0734-211X    

DOI:10.1116/1.585819

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

A new process has been developed for high resolution photolithography that employs chemisorbed monolayer films as the surface imaging layers. Organosilane treated surfaces are exposed to patterned deep UV radiation, either from excimer laser or lamp sources. The photochemical process modifies the surface wettability and reactivity of the film. Organosilane films patterned by deep UV radiation are treated with a Pd/Sn catalyst and then metallized with electroless copper and nickel baths to yield metal films several 100 Å thick. The metal is selectively deposited in the unexposed regions of the film to produce a positive tone image. The patterned metal film is then utilized as a plasma hard etch barrier in a reactive ion etch, allowing efficient pattern transfer into the underlying substrate and producing features with linewidths to 0.4 μm. Electrical testing of processed substrates demonstrates compatibility of the process with subsequent device performance, and working transistor test structures have been fabricated. Decoupling the imaging (monolayer surface imaging layer) and resist (metal film) functions of a photoresist allows separate optimization of each function in this scheme. The patterning process is very general and may be applied to a variety of substrate types. Other potential applications include patterned wettability and reactivity of surfaces for selective attachment of other species such as fluorophores or biological moieties.

ISSN:0734-211X    

DOI:10.1116/1.585820

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Ga+focused ion beam (FIB) implantation in (001) Si was conducted in our JEOL JIBL‐104UHV FIB system. Ga+ions with energy of 100 kV were implanted into silicon at doses from 1×1014to 1×1016/cm2. The current and current density of the Ga+FIB are 20 pA and 1 A/cm2, respectively. We have made patterns consisting of single‐pixel lines with various spacings and rectangular areas of different sizes. The critical dose to form a continuous amorphous region in rectangle‐scanned samples is less than 5×1014/cm2. The samples were annealed either in vacuum or a rapid thermal annealing furnace at 550–800 °C for 1/2 h and 60 s, respectively. Both cross‐sectional and plan‐view transmission electron microscopy were conducted to investigate the lattice disorder and residual defects in as‐implanted and post‐implantation annealed samples. After thermal annealing, dislocation lines and loops were observed along the line direction in line‐scanned samples. In rectangle‐scanned samples, dislocation lines and loops near the original amorphous/crystalline (a/c) interface, as well as edge defects along the edge of the rectangle were found.

ISSN:0734-211X    

DOI:10.1116/1.585821

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

A waveguide device is proposed for spot‐size transformation of an optical beam from the 1 μm range to about 8 μm using a wedge‐shaped taper. The structure can be entirely integrated on an InP‐based optoelectronically integrated circuit. It is shown by numerical simulation that the width of the thin end of the wedge has a major influence on the transformation loss of such a device. By using direct writing e‐beam lithography and reactive ion etching as well as subsequent InP regrowth, we were able to produce the required structures. The beamwidth transformation capability is confirmed by optical measurements.

ISSN:0734-211X    

DOI:10.1116/1.585823

出版商:American Vacuum Society    

年代:1991

数据来源: AIP