AZ1350 Photoresist Research Articles

Diffusion of Ag implanted into the AZ1350 photoresist

In the present work we report Ag diffusion results in the photoresist AZ1350. We have implanted Ag into AZ1350 films at very low energy ( E=30 keV) and increasing fluences, Φ=10 12 at/cm 2, 5×10 12 and 5×10 13 Ag/cm 2. Annealing was performed in the 150–270 °C temperature range and the as-implanted and diffused depth profiles were analyzed using the Rutherford backscattering technique. For the lowest implantation fluence the results show a regular atomic diffusion characterized by an activation energy of E a=650 meV. This feature shows that in this particular case we have minimized the radiation damage introduced by the implantation process and avoided the cluster formation. Instead for Φ=5×10 12 Au/cm 2 it is already possible to observe the effects of the radiation damage on the diffusion process. However even for the highest implanted fluence no evidence of cluster formation and diffusion is observed.

Diffusion and solubility of Au implanted into the AZ1350 photoresist

In the present paper we report diffusion and solubility results for Au into the photoresist AZ1350. Au was implanted into AZ1350 films at very low energy (E=20keV) and fluences (Φ=1012 and 5×1012 Au/cm2). In this way the radiation damage introduced by the implantation process was minimized and cluster formation was avoided. Annealing was performed in the 150–300°C temperature range and the as implanted and thermal treated samples were analyzed using the Rutherford backscattering (RBS) technique. For the lowest implantation fluence the results have shown a regular atomic diffusion process characterized by an activation energy of Ea=640meV. Instead, for Φ=5×1012 Au/cm2 the diffusional mechanism has revealed the effects of the radiation damage. In addition solubility measurements indicate that the solubility limit at 250°C is of the order 0.3 at.%.

Real-time and multipoint monitoring the dissolution rate of photoresist film by using a novel plastic optical fiber bundle

A novel multipoint monitoring system with a plastic-optical-fiber-bundle (POFB) based feature is presented for measuring photoresist dissolution rate. The POFB that consists of different structures at probing and receiving ends excludes the needs of beam splitters and mirrors. The mean value and the standard deviation on thickness of AZ-1350 photoresist film coated on silicon wafer were measured to be 1850 and 26 nm, respectively. A measuring error of less than 1.5% is reported by using this system. The thickness data of photoresist films on Si wafer measured by this system are in good agreement with those measured by ellipsometry. This system exhibits superiorities of more flexible structures, easier operating procedures, and lower cost in comparison with conventional ones.

Dynamical mapping and end-point detection of photoresist development by using plastic-fiber-bundle probe array

A multiport plastic-optical-fiber-bundle-based (POFB-based) metrology for dynamic monitoring of the endpoint and variation on thickness or dissolving rate of photoresist film during development is demonstrated. Experimentally, the dissolution process of the AZ1350 photoresist film at several different sites on a 150-mm (6-in) silicon wafer was dynamically monitored. The dissolving rate can be simultaneously estimated from the time-resolved optical interference reflected from the sample surface. The deviation on the thickness of PR film estimated by using the current apparatus is in good agreement with that observed by ellipsometry. The error in measurements is less than 1%, Furthermore, a two-dimensional contour mapping of the thickness of PR film on silicon wafer has been demonstrated by using 36 POFB probes.

Anomalous depth profiles and diffusional behavior of noble gases implanted into photoresist films

In the present work are reported results of thermal diffusion of Kr implanted into AZ1350 positive photoresist films and Xe implanted into “waycoat” negative photoresist films. Kr and Xe ions were implanted at 80 K and the depth profiles determined “in situ” by using the Rutherford backscattering technique in a 80–273 K temperature range. The extracted Kr diffusion coefficients follow a linear Arrhenius plot over the studied temperature range with a characteristic activation energy of E b = 100 meV. The Xe diffusion into the “waycoat” photoresist develops in a very narrow temperature range (210–230 K) which only allows determination of the diffusion coefficient at 230 K. Comparison between the present and previous published results show that Kr and Xe display very similar diffusional characteristics when implanted in the AZ1350 photoresist. On the other side, the diffusion into the “waycoat” photoresist seems to be much faster than in the AZ1350 film.

Thermal diffusion study of Xe and Cs implanted into a polymer film

We report the results of thermal diffusion studies of Xe and Cs implanted into an AZ1350 photoresist film. The Xe ions were implanted at 80 K, the depth profiles were determined “in situ” using the Rutherford backscattering technique in a 90–573 K temperature range. The extracted diffusion coefficients follow an Arrhenius type of behavior with an activation energy E b = 100meV. Similar studies performed with Cs in a 273–573 K temperature range show that the diffusional process is characterized by an activation energy E b, = 205 meV. The difference between the Cs and Xe activation energies should be attributed to Cs-photoresist chemical bonds. It is shown that the diffusion process follows a trapping-detrapping mechanism. It is found that the Xe detrapping energy is E t = 230 meV and the Cs is E t = 340 meV respectively. These facts are strong indications that the Cs-photoresist bonds play an important role in the thermal diffusional process.

Thermal behavior study of Sb implanted into photoresist film

The thermal stability of Sb implanted AZ1350 photoresist films has been investigated via the Rutherford backscattering technique. We find that a shallow Sb implantation raises the temperature at which the photoresist starts to decompose considerably. Comparison of the present results with those of Ag, Sn and Bi into the same photoresist indicates that not only radiation but also chemical effects have to be considered in order to explain the improvement of the photoresist thermal stability.

Thermal behavior study of Sn and Ag implanted into photoresist film

The thermal stability of Sn and Ag implanted AZ1350 photoresist films has been investigated via Rutherford backscattering technique. We find that a shallow Sn implantation increases the temperature at which the photoresist starts to decompose. This feature is not observed when Ag is implanted under the same conditions. These results indicate that chemical effects play an important role in the improvement of the photoresist thermal stability. We have also studied the thermal behavior of the implanted Sn and Ag ions. It was found that Sn diffuses regularly while Ag segregates toward the surface.

Low temperature diffusion study of Xe implanted into a photoresist film

We report on low temperature diffusion results of Xe implanted at 90 K into a AZ1350 photoresist. The as implanted Xe spectrum shows a regular profile with range parameters well reproduced by the theory. Successive annealings performed in the temperature range 90–293 K reveal the existence of two diffusional processes. A slow one which occurs in the near surface region and a rapid one (in the deeper zone) which is responsible for the apperance of a penetrating tail directed toward the bulk.

Range and thermal-behavior studies of Au and Bi implanted into photoresist films.

The Rutherford backscattering technique has been used to determine range parameters of Au and Bi ions implanted into AZ1350 photoresist films at energies from 20 to 300 keV. The experimental results are 20 to 25% higher than the theoretical predictions by Ziegler, Biersack, and Littmark. Good agreement is achieved only when inelastic effects are included in the nuclear stopping-power regime. In addition, we find that shallow implantation of Bi ions increases the temperature at which the photoresist starts to decompose. This feature is not observed when Au is implanted under the same conditions. Finally, we have studied the thermal behavior of implanted Bi and Au ions. While Bi diffuses regularly, Au does not follow an Arrhenius kind of behavior. In addition, it is shown that the implantation process modifies, via the nonannealed damage, the characteristics of the Bi diffusion behavior.

Radiation induced diffusion of Xe implanted into the AZ1350 polymer

The present work shows that Xe ions partially diffuse during or after room temperature implantation into the AZ1350 photoresist. Isothermal annealing performed at room temperature shows that this diffusional process is not of thermal origin. These experiments suggest that the Xe diffusion is a self-radiation induced process. In order to explore this hypothesis we have Ar-postbombarded the Xe implanted samples at a fixed energy and in a wide range of fluences. The results clearly indicate the existence of a radiation induced diffusion process via a trapping-detrapping mechanism. The trapping probability is proportional to the Xe implantation fluence and the detrapping is proportional to the Ar irradiation fluence, A final postirradiation experiment performed with Xe atoms indicates that the nuclear stopping energy transfer plays an important role in the radiation induced diffusion mechanism.

Thermal stability and diffusion studies in the Au and Bi implanted AZ1350 photoresist

The thermal stability of Au and Bi implanted AZ1350 photoresist films has been investigated via Rutherford backscattering spectrometry. It is observed that the unimplanted photoresist starts to decompose at 200°C. A shallow implantation of Bi and Au produces similar damage in the film but only the Bi implanted sample displays a marked improvement in the thermal stability (up to 350°C). This indicates that, besides radiation damage, chemical effects also play a role in the improvement of the photoresist's thermal stability. The thermal behaviour of Au and Bi implanted in the photoresist has also been studied. It was found that Bi diffuses regularly while Au follows an irregular diffusion process.

Pattern definition and formation on curved surfaces

This paper will discuss techniques used to delineate and form patterns on curved surfaces. Patterns were generated in AZ1350 photoresist using electron-beam writing and xenon–chloride excimer laser writing and ablation. Experiments were conducted on spherically concave surfaces which had a radius of curvature of 0.879 cm. Surface patterns 10 μm in width and varying in length from 40 μm to 0.6 cm were written. These beam-writing techniques show clear superiority over conventional ultraviolet photolithographic techniques for patterning nonflat surfaces. The resulting patterned photoresist can then be used as a mask for use with wet or dry etching techniques to form the desired surface features.

A New Silicone‐Based Negative Resist (SNR) for Two‐Layer Resist System

A new silicone‐based negative resist (SNR) for a two‐layer resist system was synthesized by the chloromethylation of oligomeric diphenyl siloxane (ODPS), in which the polymerization of ODPS occurred simultaneously. The molecular weight of SNR could be controlled by the reaction conditions. SNR showed excellent dry etching resistance to RIE owing to the siloxane main chain structure and high sensitivity and high resolution to electron beam, x‐ray, and deep UV radiation due to chloromethyl groups as the crosslinking units. The high glass transition temperature of SNR (150°C) due to diphenyl structure contributes to improving resolution and eliminates lithographic problems involved in low conventional silicone resins. Submicron patterns with a high aspect ratio were fabricated in a two‐layer system comprised of SNR on AZ1350 photoresist bottom layer.

Asymmetric triangular grating profiles with 90° groove angles produced by ion-beam erosion

A simple phenomenological model has been developed to account for the effects of redeposition during transverse ion-beam erosion of grating relief patterns on surfaces. The model predicts the evolution with time of an inclined facet in the substrate, and the dependence of the facet angle theta(r) on angle of incidence of the ion beam, erosion rates of mask and substrate, and the geometrical parameters of the mask. The results are illustrated by calculation of the angular dependence of theta(r) for AZ-1350 photoresist masks on GaAs and SiO(2) substrates and for Ti on SiO(2). A strong dependence of theta(r) on mask intercept angle alpha is found, except for a limited range in angle of incidence of the ion beam. Combined with results derived previously, the facet angles theta(S) and theta(r) and the groove angle theta(g) of the asymmetric triangular groove profiles produced in these systems have been determined. A groove angle of 90 degrees cannot be obtained for AZ-1350 on GaAs and SiO(2), but in appropriate conditions a 90 degrees groove angle may be obtained in SiO(2) with a Ti mask.

Generation of periodic surface corrugations

The generation of periodic surface corrugations by ion-beam milling and chemical etching of grating relief patterns in photoresist is analyzed. A general treatment is developed for gratings of any desired period on substrates of arbitrary reflectivity, but particular emphasis is given to the generation of gratings with deep grooves and fine periods (Lambda < 3000 A) on GaAs. Analysis of the intensity distribution in photoresist for both p- and s-polarized incident beams reveals that the standing waves generated by reflection from the substrate are diminished for p-polarized beams, but the existence of a displaced grating for certain ranges of substrate reflectivity and angle of incidence severely limits groove depth in resist. The requirements are given for the establishment of an intensity maximum at the photoresist-substrate interface, a condition desired for subsequent chemical etching. It is shown further that the alternative use of a quarterwave intermediate oxide layer to achieve this condition on GaAs results in a lower limit being imposed on grating period. Constantintensity contours approximating the groove profiles in resist demonstrate that an imbalance in incident beam intensity may lead to severing of the resist stripes, and the dependence of this phenomenon on substrate reflectivity is determined. For beams of equal intensity, a similar phenomenon occurs with increasing reflectivity of the substrate. The transfer of a grating relief pattern to the substrate by ion-beam milling is treated by considering the erosion profiles produced by ion bombardment. This analysis is used to examine the influence of milling geometry on the depth and shape of the groove. Although the ion-beam milling rate of GaAs is several times greater than AZ-1350 photoresist, it is shown that the groove aspect ratio (depth/period) in GaAs can be no more than about 1.2, a figure that is obtained, surprisingly, by milling at the angle of maximum removal rate of photoresist. For a metal substrate, the groove aspect ratio decreases with increasing grating period. For gratings produced by chemical etch, the problem of the weakly exposed layer of resist adjacent to the substrate is solved by using a combination of ion-beam milling and chemical etching. Using a preferential chemical etch with a sufficiently slow etch rate, gratings with well-defined planar features, a period ~2500 A, and a groove aspect ratio >0.6 have been produced on GaAs.

Characteristics of Relief Phase Holograms Recorded in Photoresists

Recording of relief phase holograms in Shipley AZ-1350 positive photoresist is investigated in this report. It is found that the use of Shipley AZ-303 developer with Shipley AZ-1350 photoresist relieves the material nonlinearity usually associated with photoresists, thereby allowing higher image readout efficiencies. The use of Shipley AZ-303 developer also provides an increase in material sensitivity. A theoretical model for positive photoresist exposure characteristics is developed and verified by empirical results. Using Shipley AZ-303 developer, a design procedure for recording useful (i.e., acceptable SNR > 25 dB, high efficiency ~3-5%, exposure sensitivity ~ a few mJ.cm(-2)) relief phase holograms in Shipley AZ-1350 positive photoresist is synthesized.

The Use of Photoresist as a Holographic Recording Medium

A technique is described for recording holograms and forming diffraction gratings in Shipley AZ1350 photoresist using the 4579-A output from an argon laser. A pre-exposure technique is described that not only reduces exposure times but increases the signal-to-noise ratio of the image. It is also shown that the effects of the variable characteristic of the resist can be alleviated by monitoring diffraction efficiency during development.