摘要:

Poly(methylmethacrylate) (PMMA) sensitized with an aromatic azide compound (4,4’‐diazidodiphenyl sulfone), was prepared and evaluated as a negative UV resist. The resist was successfully applied to contact printings followed by wet development processing. In this study, both Xe–Hg and Hg lamps were used to evaluate the sensitivity of this new two‐component resist. The sensitivity of this azide–PMMA resist depends on the azide concentration in PMMA solution, and the optimum azide concentration was found to range from 20 to 25 wt. % (based on PMMA weight). It was also found that postannealing of this resist after irradiation at 100 °C for 1/2 h can increase the sensitivity compared to no postannealing treatment. The addition of azide compound was observed to reverse the PMMA resist to negative tone for radiation doses 30 times lower than normally used in positive‐tone PMMA. The range of deep‐UV dose was 20 to 30 mJ/cm2which gave sufficiently good resolution to clearly observe mask features of 1‐μm lines and spaces.

ISSN:1071-1023    

DOI:10.1116/1.584009

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Two‐dimensional aerial image simulation and resist development withsamplefor positive photoresist along critical cross sections have been used to explore and establish models for defect interactions with features. Clear and opaque defects along a line edge give the same linewidth variation versus defect size, such as (ΔL/L)=10% for a 0.23 λ/NA defect. The resist dissolution process for large edge bias (0.14 λ/NA) and low edge bias (0.03 λ/NA) tends to terminate on constant intensity contours of 10% and 25%, respectively. The defect‐induced linewidth variation is independent of bias linewidth except for transparent intrusions into narrow resist lines and opaque protrusions into narrow spaces. Here perturbations of adjacent intensity extrema results in large‐lateral dissolution effects. Defects between two adjacent minimal sized features at a minimal spacing were used to explore critical location effects. For defects<0.2 λ/NA the results follow the algebraic model for single feature interactions and centered defects are less significant than edge defects. However, for large defects the centered case is more likely to cause openings and bridging. Line edge bias can be introduced to enhance the removal of bridging through the three‐dimensional dissolution effects at the expense of increased top loss for transparent defects. A moderate amount of line edge bias is needed to balance polarity effects and sizes up to 1/2 of the minimum feature size of 0.8 λ/NA may be tolerable.

ISSN:1071-1023    

DOI:10.1116/1.584010

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

We developed a new type of alloyed liquid‐metal ion source (LMIS) for maskless ion implantation in III–V compound semiconductors. This ion source, consisting of alloys of Au65Zn11Si24is capable of emitting Zn (p‐type dopant) and Si (n‐type dopant). The lifetime of this ion source was restricted to about 50 h due to a selective evaporation of Zn atoms from the liquid alloy surface. However, the vapor pressure of Zn in the alloy at 410 °C was estimated to be 2.3×10−3Pa (1.7×10−5Torr). This value is four orders of magnitude smaller than the elemental Zn. Using this ion source, intermixing of GaAs and AlGaAs layers was selectively performed in an undoped GaAs–AlGaAs multiquantum well structure by alternate implantation with 100‐keV Zn and 80‐keV Si focused ion beams. This disordering technique using focusedp‐ andn‐type ion beams offers the possibility of creating a variety of novel structure devices.

ISSN:1071-1023    

DOI:10.1116/1.584011

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Inspection by microtomography of active devices, tuning, and repair of III–V microstructures and microcircuits have been performed using the capabilities of combined scanning‐electron microscope (SEM) and low‐voltage (0.5–20 kV) focused‐ion‐beam (FIB), or focused‐droplet beam (FDB) system. In this instrument, the ion or droplet beams are focused simultaneously on the same point of the sample as the electron beam.Insitu(SEM) images of the region to be machined or coated are displayed before, during, and after erosion or metal deposition. Gallium and indium FIB probes of 10 to 20 kV were used to cut functional parts of devices such as heterojunction bipolar transistors or field‐effect transistors. Strong chemical contrast in the SEM mode displays very distinctly the different levels of the structure. This constitutes a promising method for fast nondestructive on‐line control testing of a given device. Cuts of electrical connections have been realized. Surface resistance effects induced by the ion impact have been observed. Accurate resistor adjustment has been realized by FIB milling and controlled byinsitumonitoring of the resistance. Indium and gold droplet beams have been focused on GaAs substrates. Best emission and focusing conditions have been determined giving deposited domains smaller than the structures previously obtained. Conducting connections have been fabricated by scanning the FDB and monitored byinsiturecording the resistance during the establishment of the conducting bridges.

ISSN:1071-1023    

DOI:10.1116/1.584012

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

ISSN:1071-1023    

DOI:10.1116/1.584013

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Despite the many reports on characteristics of hydrogen field ion (FI) sources, there have been only a few reports on focusing experiments. We developed a stable helium FI source and a focusing column with a gimbal assembly for beam axis alignment, and carried out focusing experiments. Scanning ion microscope images of a Au wire were observed using the focusing column. From the image resolution, the ion probe diameter was estimated to be ∼200 nm. We exposed a 260‐nm‐thick polymethylmethacrylate resist on a Si substrate, which produced 200‐nm‐wide lines. A 70‐nm‐wide space was also formed. The proximity effect was negligible even if the space between the lines was 100 nm. Thus, we confirmed that a helium FI source is suitable for fine pattern lithography.

ISSN:1071-1023    

DOI:10.1116/1.584014

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

A computer controlled focused‐ion‐beam system (JIBL‐200S) with a new optical design concept has been developed. The JIBL‐200S has good focusing properties over a wide‐accelerating voltage range. A double‐mode optical system has been provided in order to improve the focusing properties for the low‐accelerating voltage region. In this system the two einzel lenses are operated in the decel mode (central electrode positive) for beam accelerating voltages above 100 kV and in the accel mode (central electrode negative) below 100 kV. This reduces a chromatic aberration for the low energy beams. The beam diameter for a Ga ion was measured using a knife edge and Faraday cup. As a result, compared to the conventional mode of operation, the beam size is improved to 0.09 from 0.15 μm at 75 kV and to 0.13 μm from 0.20 μm at 50‐kV‐accelerating voltage by changing the operating mode. The writing performance was also evaluated by the use of a vernier pattern writer on a Si substrate coated with chloromethylated polymethylstyrene resist exposed with 250‐keV‐Si++ions. Overlay accuracies of 0.183 μm in theXaxis and 0.243 μm in theYaxis 3σ were obtained.

ISSN:1071-1023    

DOI:10.1116/1.584015

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Anisotropic profiles and linewidths as small as 60 nm have been controllably achieved using pattern transfer by dry etching through stencil masks. This technique eliminates the conventional polymer resist and lithographic steps and could be useful in obtaining precisely reproducible submicrometer linewidths without variation due to run‐to‐run variability in resist processing. The stencil masks used in this study were 1‐μm‐thick SiNxmembranes with transmission openings and are similar to those used for masked ion beam lithography. The dry etching techniques consisted of reactive ion etching, ion beam assisted etching, and hot jet etching. The profile and linewidth control depend on the divergence of the ion or reactive flux and the gap between the stencil mask and the sample.

ISSN:1071-1023    

DOI:10.1116/1.584016

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Ion beam etching (IBE) of GaAs was carried out at an energy of 1 keV using Ar and CCl2F2as a source gas and defect center induced by IBE was investigated by means of deep level transient spectroscopy and carrier profile measurements. From DLTS measurements, five different defect centers (electron traps) were resolved. They were distributed far beyond the ion range and showed different depth profiles. The deep distribution of IBE induced defects was also confirmed from the carrier profile measurement. Annealing at 500 °C was effective to reduce the observed defect centers but defect centers with a concentration between 1×1015and 5×1016/cm3still remained.

ISSN:1071-1023    

DOI:10.1116/1.584017

出版商:American Vacuum Society    

年代:1988

数据来源: AIP

摘要:

Reactive ion etching of single‐crystal and polycrystalline silicon in bromine has been studied at 2‐mTorr pressure in a magnetically enhanced reactor. Effective voltage thresholds for silicon and thermal SiO2etching are observed at −50‐ and −175‐V cathode bias, respectively. The selectivity of silicon with respect to SiO2exhibits a sharp peak between these thresholds, attaining, at −100 V, a value of 225 forp‐type and lightly dopedn‐type material. The corresponding etch rate is 65 nm/min. The etch rate doubles forn+‐polysilicon and the peak selectivity is 450. Etching is anisotropic over the entire doping range. Application of the −100‐V process to high‐resolution trench and polysilicon gate fabrication is discussed.

ISSN:1071-1023    

DOI:10.1116/1.584018

出版商:American Vacuum Society    

年代:1988

数据来源: AIP