摘要:

We report the growth and operation of a ZnSe/ZnCdSe quantum well light emitting diode (LED).I–Vcharacteristics confirm the presence of ap–njunction and are similar to those previously reported for homojunction ZnSe LEDs. The room‐temperature electroluminescence spectrum exhibits strong recombination at the quantum well, demonstrating effective confinement and high‐quality materials. The electroluminescence is studied as a function of temperature and operating current of the device.

ISSN:1071-1023    

DOI:10.1116/1.586433

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Buffer layer configurations consisting of magnetron sputtered ZrO2, Zr–Si mixed oxide, and SiO2were investigated for sputter deposition of Bi–Sr–Ca–Cu–O high‐Tcsuperconducting thin films onto silicon wafers. A problem associated with film flaking during postdeposition annealing was overcome by burying the sample in a powder of Bi–Sr–Ca–Cu–O material. Crack growth and buckling in the buffer layers, associated with differential thermal expansions, were eliminated by raising the deposition temperature for the buffer layers. Unfortunately, the improved buffer layers were not good enough to prevent substrate–film interactions over the long annealing times (e.g., 14 h), and the sufficiently high temperature (e.g., 850 °C) needed for the formation of the 2223 highTc(110 K) phase.

ISSN:1071-1023    

DOI:10.1116/1.586434

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Most surface imaging resist schemes are based on the selective diffusion of a Si‐containing compound into the resist. In the diffusion enhanced silylated resist process hexamethyldisilazane is being incorporated in the exposed regions during the silylation treatment. Upon deep ultraviolet irradiation (at 248 nm), novolac based resists will however crosslink to some extent. The crosslinking reaction influences the degree of silicon incorporation in the exposed resist and hence plays an important role in the imaging properties. The crosslinking reaction has been studied in detail in this work for two types of Plasmask deep‐ultraviolet resists, along with its consequences on resist imaging. A decrease in silicon incorporation due to crosslinking puts a serious limitation on the useful process window for Plasmask 150u, but the process window is not limited by crosslinking for Plasmask 301u. A thorough investigation of the influence of crosslinking on the pattern deformation is also carried out.  

ISSN:1071-1023    

DOI:10.1116/1.586435

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

The dependence of the dissolution rates of phenolic resins on the base concentration of the developer can be described by a dimensionless equation based on a membrane model of novolak dissolution [J. P. Huang, T. K. Kwei, and A. Reiser, Macromolecules22, 4106 (1989) and R. A. Arcus, Proc. SPIE631, 124, (1986)]. The resin is characterized by a dissolution thresholdc0, which is a limiting base concentration below which dissolution no longer occurs, by a scaling exponentnand by a membrane permeabilityPrwhich refers to a developer of base concentrationc= 2c0. Under these reference conditions all resins are in a corresponding state and dissolve with the same dimensionless rate ofR/Pr= 0.5. The inhibition effect in an inhibitor/resin pair is represented by a plot of log(Ri/R0) against the inhibitor concentration in the resin matrix, whereRiis the rate of dissolution of the inhibited,R0the rate of dissolution of the pure resin. The slope of this plot is independent of the inhibitor concentration over a reasonable concentration range and may be termed the inhibition factor and used as a measure of the inherent inhibition capability of the inhibitor in the resin. It is termed the inhibition factor. It is suggested that inhibition factors be compared in conditions where the pure resins dissolve at the same rate. In this study we have chosen a rate of 15 μm/min as the standard condition.

ISSN:1071-1023    

DOI:10.1116/1.586436

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

In order to obtain precise pattern dimension control, optical indexes of the middle layer (ML) in a trilayer resist system are investigated. Photoabsorption in ML and bottom layer (BL) is important. However, optimization of photoabsorption in these layers is not sufficiently to suppress linewidth variations. From calculations of the reflection at each interface of the trilayer resist system, the matching of the refractive index between each layer [top layer (TL), ML, and BL] is found to be also important. The optimal refractive index of the ML for the novolac‐type of TL and BL materials is estimated to be 1.7 atiline, which is the same value as that of novolac resin. To confirm this matching effect, an admixture material of Ti–alkoxide and silanol is used as the ML material. The mixing ratio is 50 wt %. The refractive index of this material with curing at 230 °C is 1.7. Using this material, the linewidth variation caused by the interference effect can be reduced as 0.04 μm, which is half that using spin‐on glass as the ML. The material also shows a high O2reactive ion etching resistance (1.7 nm/min) and good adhesion to the TL and BL. In the trilayer resist system, it is possible to fabricate a fine, precise pattern even on a large topography.

ISSN:1071-1023    

DOI:10.1116/1.586437

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

A deep ultraviolet photoresist based on 1,1’(dodecamethylene)bis(3‐diazo‐2,4‐piperidinedione) and poly(3‐methyl‐4‐hydroxystyrene) can be esterified at room temperature if the ultraviolet exposure is performed in a dry environment. No water‐free bake treatment during or after the exposure is necessary to obtain a high degree of esterification, as in the case of conventional diazonaphthoquinone/novolak based photoresists. Patternwise esterification results in 0.45 and 0.35 μm lines and spaces in the wet developable image reversal and the dry developable submicron positive dry etch resist process, respectively, using a 248 nm contact exposure.

ISSN:1071-1023    

DOI:10.1116/1.586438

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

A new optical focus system for wafer steppers, insensitive to structures on the wafer surface, is presented. It is based on the grazing‐incident beam method. In traditionally used monochromatic focus systems, interference effects in the layer stack on the wafer are a severe limitation on the accuracy. In the system presented here, this problem is overcome by using an incandescent lamp as a polychromatic light source. Due to the large spectral range of 300 nm, interference effects in the layer stack on the wafer are averaged. Calculations of the influence of these interference effects on the focus measurement show good agreement with the experimental results. An additional feature of the system is its large measurement spot, which averages effects related to locally varying reflection and topography. Moiré fringe and modulation techniques are used to enhance the signal‐to‐noise ratio. As a result the dynamic range of the system is increased to 103. The mechanical stability is considerably improved by the addition of a reference branch that measures the position of the projection lens. This enables the accurate and precise measurement of the required distance between lens and wafer. The extra optical features together with the mechanical stability yield a vertical accuracy and precision better than 100 and 20 nm, respectively. The combination of four of these focus systems within one stepper permits the measurement of the local tilt of the wafer.

ISSN:1071-1023    

DOI:10.1116/1.586439

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Atomic force microscopy (AFM) was used to image the surface of SrF2(111) with resolution of individual fluorine ions. A SrF2single crystal was cleaved along the (111) plane and imaged under 0.01 M HCl solution to remove contaminants. In some areas the hexagonal arrangement of the ions is clearly visible with interionic spacings of 3.96 Å, which is in good agreement with the crystallographical data. Studies of the epitaxial growth of alkaline earth fluorides on semiconductors may now be possible with AFM.

ISSN:1071-1023    

DOI:10.1116/1.586440

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Radiation‐induced degradation in packaged metal–oxide semiconductor field effect transistors (MOSFETs) can be efficiently removed by an anneal treatment carried out at 350 °C for 10 min in N2. The electrical characteristics of the MOSFETs including threshold voltageVth, transconductanceGm, and drain currentIdwere examined in the recovery of device performance. The irradiation was performed by a Co‐60 (γ‐ray) source with the irradiation total doses ranging from 10 K rads to 10 M rads. Experimental results show that the anneal treatment can be repeatedly performed on a sample after receiving multiple irradiation and the recovery behavior is quite good for each anneal treatment. The determination of the temperature and the anneal time are also discussed.

ISSN:1071-1023    

DOI:10.1116/1.586441

出版商:American Vacuum Society    

年代:1992

数据来源: AIP

摘要:

Probes that can monitor and control crystal growth in real time could significant improve sample yield and material reliability. We are developing one such probe, spectroellipsometry, for controlling growth by organometallic molecular beam epitaxy. Our system is presently capable of holding the composition of thick AlxGa(1−x)As layers constant to a precision of ±0.1%, and has been used to control growth of purposely compositionally graded structures, such as parabolic quantum wells 200 Å wide.

ISSN:1071-1023    

DOI:10.1116/1.586442

出版商:American Vacuum Society    

年代:1992

数据来源: AIP