摘要:

A clean, stable boron evaporator has been designed and constructed. The design involves heating one end of a boron rod by a combination of radiation and electron beam heating. The evaporator was tested by doping polycrystalline silicon thin films by coevaporation. Doping levels up to 2×1020cm−3were obtained with 100% electrical activation. No metallic contamination was found in the thin films using secondary ion mass spectroscopy.

ISSN:1071-1023    

DOI:10.1116/1.584956

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The mechanism that governs the in‐plane solvent (N‐methyl pyrrolidinone) diffusion in a soluble polyimide [3,3’,4,4’‐benzophenone tetracarboxylic acid dianhydride and diaminophenylindane (BTDA‐DAPI)] lift‐off structure was investigated. Using a metal‐on‐polyimide test pattern along with a surface profilometer, the solution process was shown to occur in three stages. A thermal‐activated diffusion process which follows thet1/2Fick’s law was observed as solvent molecules diffuse laterally (parallel to the film plane) underneath the metal pad, which serves as a solvent diffusion barrier, into the soluble polyimide film. The diffusion coefficients are described by the expression:D=0.0005 exp(−3600 cal/RT) cm2/s, over the 40–85 °C temperature range. Behind the diffusion front was a region of solvent/polyimide (PI) swollen gel with increasing solvent concentration away from the front. After a maximum solvent concentration was reached, the swollen gel began to disintegrate into the solvent bath. This gradually led to a completely dissolved region behind the swollen gel. The rate of solvent diffusion was very close to that of dissolution. Both were governed by the peak PI curing temperature, solvent temperature, and the types of solvent used. Based on this study, the total time required to lift off evaporated metal on top of the stencil can be calculated from the diffusion coefficients and the induction time obtained at each temperature.

ISSN:1071-1023    

DOI:10.1116/1.584957

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The simultaneous application ofinsituellipsometry and quadrupole mass spectrometry to the reactive ion etching of polysilicon/SiO2/Si(100) multilayers in pure Cl2plasmas at 13.56 MHz is described. At 100 mTorr and 50 W the surface texture of the unetched polysilicon is retained, but significant roughening is induced when the power is raised to 100 W. Water vapor is shown to play a critical role in the roughening process and is probably due to micromasking by hydroxide groups at the polysilicon surface. Detailed models of the ellipsometric results for roughened surfaces are derived and correlated with their scanning electron microscopy images. When CClx(x=1–4) species are present in the plasma, due to the erosion of a carbon‐containing resist, roughening of polysilicon is prevented at 100 W and the etch rate of the underlying SiO2is increased. Accompanying this increase is a shift in the product distribution for SiO2towards higher SiCl4but lower O2. In contrast the etch rate and product distribution for polysilicon remain almost unaffected by the presence of resist.

ISSN:1071-1023    

DOI:10.1116/1.584958

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Ti‐capped Al–Si films are more susceptible to post‐etch corrosion than uncapped Al–Si films. The extent of corrosion of Ti‐capped films is related to post‐etch treatment. Various post‐etch treatments to reduce chlorine concentration are evaluated by x‐ray fluorescence analysis. Results of single‐ and multiple‐step treatment, such as baking, partial resist stripping in oxygen plasma in the exit chamber, water rinse, and resist partial stripping followed by wet stripping are presented. A method to estimate the surface concentration of chlorine in atoms/cm2is described; the chlorine concentration in most cases is less than 5×1015atoms/cm2.

ISSN:1071-1023    

DOI:10.1116/1.584959

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

TiSi2has the lowest resistivity among various refractory metal silicides and a low forming temperature also. It is considered that TiSi2would be an important material for the scale above 4M dynamic random access memory integration, it has given rise to universal attention. In this paper, reactive ion etching characteristics of TiSi2/n+polysilicon polycide structure are investigated in detail, and the probable mechanisms are discussed. The mixture of SF6–Cl2is chosen as etch gases for TiSi2polycide patterning. The experimental analysis indicates that the etch rates are dependent on various etching process parameters, such as gas composition, radio frequency power, and gas pressure, the etching profiles are dependent on gas composition. Strict anisotropic etching of TiSi2/n+polysilicon double layer structure with 0.6 μm linewidth has been achieved by a single‐step process. The etch rate ratio ofn+polysilicon to TiSi2is equal to 1.03 and that ofn+polysilicon to SiO2is equal to 18. The integrity of resist mask is good. The reproducibility of the process is satisfactory.

ISSN:1071-1023    

DOI:10.1116/1.584960

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Perfect selective and highly anisotropic etching for tungsten polycide (WSix/poly‐Si) structure without sidewall protection is achieved at the electron cyclotron resonance (ECR) position in a newly developed ECR plasma etching system. The etching selectivity ratio of WSix/poly‐Si structure etching to SiO2etching is infinite by using Cl2/SF6/O2gas mixture under 5×10−4Torr. The etching rate is more than 2000 Å/min with no radio frequency bias above selectivity conditions. The addition of a small amount of SF6is efficient for removing tungsten residue. The perfect etching selectivity is caused by low ion energy at the ECR position and the effect of O2gas addition. The high etching rate is achieved by high ion current density at the ECR position. Furthermore, a highly anisotropic etching profile is realized at the substrate temperature of 60 °C.

ISSN:1071-1023    

DOI:10.1116/1.584961

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Using aninsitustress measurement technique that measures stress as a function of annealing temperature, instabilities in mechanical stress induced by heat treatment in a variety of doped/undoped SiO2films deposited by atmospheric‐pressure chemical vapor deposition (APCVD), low‐pressure chemical vapor deposition (LPCVD), and plasma‐enhanced chemical vapor deposition (PECVD) techniques have been investigated. A large hysteresis in mechanical stress, caused by first heat treatment to which the as‐deposited films are subjected, has been observed in films deposited by APCVD/LPCVD techniques. No such hysteresis is observed in films deposited by PECVD technique. Hysteresis in APCVD/LPCVD films is found to vanish once the films are heat treated at or above 800 °C. Stress behavior of heat treated (≥800 °C) films is found to resemble that of thermally grown SiO2films and can be described by simple elastic theory. During the first annealing cycle, APCVD/LPCVD films have been found to develop stress levels as large as an order of magnitude higher than their as‐deposited stress value. Maximum stress developed in the film during heat treatment and the temperatureTRat which maximum stress occurs have been found to be dependent on phosphorous content in the film. For heat treatment below this temperatureTR, the stress on cooling becomes significantly larger than the as‐deposited stress. The results are discussed in terms of oxide densification, the presence of hydrogenous species, and phosphorous.

ISSN:1071-1023    

DOI:10.1116/1.584918

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Independent adjustment of etch rate and sidewall profiles in chemically assisted ion beam etching (CAIBE) of GaAs is demonstrated by controlling the temperature of the sample. GaAs etch rate data as a function of sample temperature, ion beam flux, and reactive gas flow is presented for CAIBE using a 500 eV argon ion beam and molecular chlorine. At a constant etch rate of 0.5 μm/min, etch profiles ranging from vertical to crystallographically faceted are obtained. This demonstrated flexibility, combined with the inherent reproducibility of dry etching, make CAIBE an attractive choice for processing advanced semiconductor devices. To illustrate the range of capabilities available with temperature‐controlled CAIBE, etched‐facet laser structures, self‐aligned mesas and fine tips suitable for field‐emitting devices are fabricated.

ISSN:1071-1023    

DOI:10.1116/1.584919

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

A three‐dimensional (3D) photolithography simulator was developed which is composed of the two‐dimensional (2D) mask aerial image simulator, simulator for 2D intensity pattern in aligner (STIPAL), and the 3D resist image simulator, resist process 3D simulator (RESPROT). STIPAL can calculate the mask aerial image in projection printing considering lens aberrations and reticle defects which are very important factors influencing submicron pattern transfer, in addition to the parameters of lens NA (numerical aperture), source wavelength λ, partial coherency σ and defocusing. RESPROT can simulate the 3D resist image in a conventional resist process and contrast enhancement lithography (CEL) using the mask aerial image data calculated by STIPAL. Resist pattern printability or fidelity in the submicron process can be analyzed by these simulators. Resist linewidth shifts caused by reticle defects and lens aberrations were analyzed. Effects of a dark defect (a surplus pattern) or a clear defect (a lack of pattern) on the resist linewidth shifts are almost the same when defocusing and/or lens aberration do not occur. When defocusing and/or lens aberration occur, however the resist linewidth shift caused by a dark defect is larger than that caused by a clear defect. A high resolution photoresist and CEL can decrease the resist linewidth shift caused by mask defects. Further, CEL can decrease oval distortion of the submicron contact hole pattern caused by lens aberration.

ISSN:1071-1023    

DOI:10.1116/1.584920

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

A variety of techniques were developed to enable the fabrication of submicron resistors suitable for conductance and noise measurements. Small wires with effective diameters of 400 Å and lengths of 750–2000 Å were fabricated by these means. The techniques are suitable for the fabrication of wires with lengths down to less than 500 Å and effective diameters down to less than 150 Å, and require only standard photolithography and thin film deposition equipment. The processing schemes are an offshoot of those previously developed by Proberetal. [Appl. Phys. Lett.37, 94 (1980)] for the fabrication of long (>1 μm) small‐diameter wires. The techniques reported here include an improved method for making long wires, an alternative method for materials that cannot be handled by that approach, and new techniques to enable the fabrication of wires with lengths well below the 1 μm limit of standard photolithography.

ISSN:1071-1023    

DOI:10.1116/1.584921

出版商:American Vacuum Society    

年代:1990

数据来源: AIP