摘要:

The use of amorphous As layers to protect compound semiconductor surfaces when transferred in air among ultrahigh vacuum systems has been demonstrated for III–V materials containing As and group III metals such as Ga. We have extended this passivation, or capping, technique to a new class of materials: the II–VI semiconducting compounds, typified by ZnSe. This capping procedure allows transfer among noninterconnecting systems resulting in clean, highly ordered, and stoichiometric surfaces suitable for heteroepitaxial growth, other fabrication procedures, and fundamental studies.

ISSN:0734-211X    

DOI:10.1116/1.585604

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Schottky barrier photodiodes have been fabricated onp‐type Hg1−xCdxTe, compositionx=0.22 and carrier concentration from 6×1015to 5×1016cm−3, with Au and Ti as contact metals. It has been found that Au barrier height is lower than that of Ti for all carrier concentrations. Low temperature annealing, 75 °C for 24 h, reduces the effective Au barrier height and raises the Ti barrier height. The electrical results are correlated with Auger depth profiling of the difference interfaces, and transport mechanisms are proposed.

ISSN:0734-211X    

DOI:10.1116/1.585605

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Halogenated organic compounds incorporated into novolac‐based resists act as tracers and provide a specific end point detection (EPD) signal which can characterize the transition between resist layers during plasma etching. The EPD signal is supplied by the plasma induced emission intensity of the halogen resonance lines, all located in the VUV spectral region. Two chlorine—and bromine—based tracers have been selected which provide specific and convenient EPD signals to monitor the etching of multilayer systems. The basic criteria for an organic compound tracer to be incorporated into novolac‐based resist are discussed.

ISSN:0734-211X    

DOI:10.1116/1.585606

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

A new method was developed to study the diffusion of photogenerated acid in chemical amplification resist systems which allowed an estimation of the diffusion range by simple means. The acid mobility was investigated for two different resist systems under various process conditions. It was found that solvent traces in the film cause a very strong increase of the acid mobility. In order to control the diffusion range, the post‐exposure‐bake temperature must be below the glass transition temperature. For one resist system, the increase in resist sensitivity with increasing baking temperature was much smaller than the corresponding increase in diffusion range. The results corresponded well with those obtained by lithography with the same resist.

ISSN:0734-211X    

DOI:10.1116/1.585607

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Optimization and synthesis of electrostatic unipotential and retarding two‐interval spline lenses have been carried out from the point of view of the spherical and chromatic aberrations. The figures of merit to express the lens performance are the spherical and chromatic aberration coefficients referred to the object, calculated in infinite magnification mode, and related to the object side focal length. The computations are based on a direct numerical ray tracing method that is suitable to solve either relativistic or nonrelativistic problems. Conditions for the calculations and optimization constraints are prescribed in compliance with the practice. A three‐electrode unipotential spline lens and a two‐electrode immersion one have been found as optimum according to the spherical aberration, and they are presented as examples. The spherical figures of merit of the unipotential and the immersion lens areCso/fo=9.17 andCso/fo=6.70, respectively. The immersion lens has a local minimum chromatic figure of merit too.

ISSN:0734-211X    

DOI:10.1116/1.585608

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Mixing of double‐layered Al‐on‐Au and Al‐on‐W structures by a focused ion beam (FIB) has been used to define fine patterns in Au and W layers and to demonstrate that the mixing spread is less than 0.1 μm. Since the mixed Al–Au alloy and Au have higher sputtering yield than Al, etching with 4‐keV Xe ions engraves the FIB‐defined pattern in the Au layer. This process yielded 0.2‐μm‐wide grooves in 20‐nm Al/0.3‐μm Au with a 50‐keV Ga+FIB of ∼5×1015/cm2. In the Al/W, Al is removed in H3PO4leaving the mixed Al–W alloy, which acts as a durable mask in SF6reactive ion etching of W with a selectivity of ∼80. This process enables the Ga+FIB to define patterns less than 0.1 μm in 20‐nm Al/0.3–0.5‐μm W with a sensitivity of ∼1×1015/cm2. To demonstrate applicability of the above processes, patterns of x‐ray masks were fabricated and transferred with synchrotron radiation to poly‐methyl‐methacrylate. Backscattering measurements of He ions and x‐ray diffraction verify mixing occurs within the range of the ion. The process performance and its relation with the mixing kinetics are also discussed.

ISSN:0734-211X    

DOI:10.1116/1.585609

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

The atomic force microscope (AFM) can be used to generate both images and height profiles of samples with micron‐sized features, combining the resolution and speed of the scanning electron microscope and the height information of the stylus profilometer. We have increased the scan speed of our AFM so that these images may be taken in real time, allowing the operator to interact easily with the microscope parameters. The increased scan speed does not noticeably degrade the images. The resulting images contain complete height information, allowing height profiles to be extracted. In this paper, we present images taken in this manner as well as discuss some of the nonideal characteristics of the AFM, such as tip‐shape artifacts, tip contamination, sample damage, and scanner nonlinearities.

ISSN:0734-211X    

DOI:10.1116/1.585610

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

The results of a study of the mode transitions in the helicon source when used in the geometry required for plasma processing are presented. We find that the basic characteristics of high density (>5×1011cm−3in the processing chamber at 500 W) and low plasma potential (∼15 V) are observed in this configuration. The mode transitions can be interpreted in terms of the dispersion relation for the helicon wave. A study of the initial plasma breakdown has also been made and the results have aided in the understanding of the operation of the helicon source during pulsed plasma etching.

ISSN:0734-211X    

DOI:10.1116/1.585611

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

The initial operation of an electron cyclotron resonance (ECR) plasma etch tool, utilized in a downstream configuration for SF6etching of polysilicon is described. Practical operational characteristics that are generic to high‐density, wave‐supported plasma sources operated in downstream configurations were explored. A method for improved coupling of the microwave power to the ECR source is described. This method eliminates the need for external tuning. The effect of wall impurities on the plasma and etching characteristics is also considered. A scheme for conditioning the walls to alleviate the effects of impurities is presented. Finally, the complicated relationship between the ECR source plasma and the downstream wafer is considered, by examining the scaling of the plasma electron density in the two regions with microwave power and gas pressure. The phenomena discussed here apply to other etching chemistries and can have a significant impact on process integrity and ease of operation.

ISSN:0734-211X    

DOI:10.1116/1.585612

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

A new type of plasma etcher named a supermagnetron plasma etcher equipped with two parallel cathodes and an annular permanent magnet was developed. Using the supermagnetron plasma etcher, two kinds of experiments for the high rate etching of SiO2and the highly uniform etching of photoresist and SiO2under a stationary magnetic field were investigated. In the etchings of 6‐in.‐diam bare and patterned SiO2wafers, high etch rates of 570 and 710 nm/min were obtained, respectively, using C2F6gas of 7.5 mTorr. The etch selectivities of SiO2to Si became as high as 6–15 using CHF3gas at 3–6 mTorr. In a stationary magnetic field, the highly uniform etching of photoresist and SiO2were also obtained using two types of supermagnetron plasma etchers. The etch uniformities depend on rf powers supplied to the upper and lower cathodes, gas pressure, and the position of a magnet, etc. High etch uniformities of ±5% were obtained without the rotation of a magnetic field in the etching of 3‐in.‐diam photoresist film and 6‐in.‐diam SiO2at phase differences of rf voltages of about 180 and 250 degrees, respectively. Applying the CHF3and O2supermagnetron plasmas to submicron pattern etchings, SiO2contact holes with tapered side walls and photoresist lines with vertical side walls were obtained, respectively.

ISSN:0734-211X    

DOI:10.1116/1.585613

出版商:American Vacuum Society    

年代:1991

数据来源: AIP