摘要:

The reactive ion etching ofp‐InGaP andp‐GaAs using CH4/H2was examined through design of experiment techniques. The etch rate of InGaP and GaAs, the etch rate ratio of InGaP over GaAs, and the dc bias were optimized by fractional factorial design as a function of total gas flow rate, methane composition, total pressure, and rf power. It was found that the rf power and the total chamber pressure were the most significant parameters in the reactive ion etching process. Models were created to describe the change of each response over a range of etching parameters.

ISSN:1071-1023    

DOI:10.1116/1.588810

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Reactive ion etching of GaSb and GaAlSb using pure SiCl4was investigated. Etching rate and etching profiles were characterized as functions of working pressure, chamber background pressure, flow rate, and power density. The etching rate and profile of metal organic chemical vapor deposited‐grown GaSb and GaAlSb thin films are strongly dependent on background pressure and applied power. These interesting characteristics can be applied to control selective or nonselective etchings for device fabrication. Etching profiles exhibited a high degree of anisotropy and smooth surface morphologies.

ISSN:1071-1023    

DOI:10.1116/1.588811

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Dry etching mechanisms of thermal and photochemical reactions with Cl2and HCl on GaAs(100) Ga‐richc(8×2) surfaces were investigated, using x‐ray and ultraviolet photoelectron spectroscopy. At a substrate temperature of −100 °C, the etchant gases are chemisorbed on the GaAs surface. Cl2deposition on GaAs produces about five times more Cl‐containing species than HCl deposition. The GaAs surface is disrupted with Cl2when the substrate temperature is increased to 250 °C after the saturated deposition of Cl2at −100 °C. A similar etching procedure with HCl forms an ordered surface of GaAs with As atoms on the top layer. After desorption of the etchant gases, the photoirradiation effect at room temperature was investigated by pulsed laser irradiation with excimer (193 and 248 nm) and YAG (266, 355, and 532 nm) lasers at an intensity of 2–10 mJ/cm2. Only the 193 nm irradiation removes Cl‐containing species from the surface. With cw laser irradiation at 488 nm (60 mW/cm2), photochemical reactions take place on the GaAs substrate on which Cl2has been deposited.

ISSN:1071-1023    

DOI:10.1116/1.588812

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Process simulation is going to play an ever increasing role in the development, process optimization, and production of integrated circuit devices, yielding shorter development times and reduced costs as compared to traditional development methods. One of the most notorious problems one faces in topography simulations in particular is the determination of the erosion/growth rates of materials exposed to a variety of complex physicochemical processes. The latter evolve continually to satisfy the needs of the ever advancing microelectronic industry, while our understanding about these processes is often incomplete and insufficient for their description. Existing theoretical models, which are often semiempirical, include a set of fitting parameters which are generally unknown and their determination in most cases involves guesswork. Another much more pragmatical approach to the problem is to measure these etch/growth rates directlyinsituin the production equipment and feed the data into a topography simulator. In this article we present a simple and general method for measuring the angular dependence of the etch rate of a variety of materials using specially patterned silicon wafers. With anisotropic wet etching of silicon wafers it is possible to create structures defined by specific crystallographic planes, thus producing a variety of planar orientations on one and the same wafer. The structures can be oxidized and coated with the material of interest and processed under standard operating conditions. The method will be presented together with angular dependence data from typical dry etching processes. The results will be used as an input to the topography simulation programDINESE.

ISSN:1071-1023    

DOI:10.1116/1.588813

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

A Au (1000 Å)/Ge (100 Å)/Pd (100 Å) contact scheme has been investigated to form low resistance Ohmic contact ton‐Al0.5In0.5P (Eg=2.3 eV) with a minimum contact resistivity of about 1×10−6Ω cm2. The surface morphology of this contact remained smooth after annealing at 425 °C for 1 min. Front side secondary ion mass spectrometry depth profiles of this contact structure under different annealing conditions were performed. It is found that the outdiffusion of indium due to the reactions between the metallization and the Al0.5In0.5P substrate in conjunction with the indiffusion of Ge into the substrate is responsible for the Ohmic contact formation. The germanide formation is believed to be responsible for the smooth surface morphology. The contact resistivity of this contact remained ∼2×10−6Ω cm2after aging at 350 °C for 31 h.

ISSN:1071-1023    

DOI:10.1116/1.588814

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

We have developed a novel subquarter micron gate fabrication process without any electron beam (EB) lithography techniques or phase shift (PS) methods. To fabricate a subquarter micron width mask, the process uses thinning line patterns of photoresist by O2reactive ion etching and the reversing of that resist by a thin Al film. We applied this process to fabrication of a pseudomorphic AlGaAs/InGaAs high electron mobility transistor. The device exhibited a peakgmof 715 mS/mm,fTof 95 GHz, andfmaxof 176 GHz. These results show this process to be a useful alternative to EB or PS techniques for subquarter micron gates.

ISSN:1071-1023    

DOI:10.1116/1.588815

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The interface chemistry and the electrical properties of annealed Ni/Al–6H SiC Ohmic contacts are studied by using x‐ray photoemission spectroscopy, current–voltage characteristics, and contact resistance measurements employing a four‐point method. All depositions and analysis were performed on the Si face of nitrogen doped,n‐type (1×1018cm−3) wafers of 6H SiC (0001). The chemical reactions at the interface are revealed. Al at the SiC interface acts by reducing the SiOxand forming Al2O3. At elevated temperatures, SiC in the presence of Al dissociates with formation of Al4C3which is a stable compound. At about 1000 °C the Si atoms at the interface bond to Al and Ni either in ternary compounds with different stoichiometry or in NiSi. In the subsurface region carbon is present in the graphite state of ∼5 at. %. The Ohmic behavior of the contact is related to the formation of the NiSi while the weak contact resistivity degradation is due to the low graphite precipitation. The improved temperature stability may also be due to the presence of Al2O3on the top of the contact structure.

ISSN:1071-1023    

DOI:10.1116/1.588816

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The addition of light rare‐earth (RE) metal elements (La, Pr, and Nd) to Al thin films with about 2–7 at. % markedly decreases the grain size of the Al matrix more than 50% compared with those of pure Al. Such addition largely suppresses growth of thermal defects of hillocks and whiskers at high temperatures (350–450 °C). A large number of fine metallic compounds of Al11RE3and/or Al3RE (RE=La, Pr, and Nd) were segregated in an Al matrix, mostly at grain boundaries, after annealing at 350 °C. The resistivities of the films after annealing at the above temperatures show low values of less than 6 μΩ cm compared with those of current thin‐film‐transistor liquid‐crystal displays gate electrode materials (more than about 15 μΩ cm), without the salient formation of hillocks or whiskers on the surfaces.

ISSN:1071-1023    

DOI:10.1116/1.588817

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Tantalum (Ta) and tantalum nitride films (Ta2N and TaN) of about 50 nm thickness were reactively sputter deposited onto (100) Si substrate by using dc magnetron sputtering and their diffusion barrier properties in between Cu and Si were investigated by using sheet resistance measurement, x‐ray diffraction, Auger electron spectroscopy, and Secco etching. With increasing amounts of nitrogen in the sputtering gas, the phases in the as‐deposited film have been identified as a mixture of β‐Ta and bcc‐Ta, bcc‐Ta, amorphous Ta2N, and crystalline fcc‐TaN. Diffusion barrier tests indicate that there are two competing mechanisms for the barrier failure; one is the migration of Cu into the Si substrate and another is the interfacial reaction between the barrier layer and the Si substrate. For instance, we identified that elemental Ta barrier failure occurs initially by the diffusion of Cu into the Si substrate through the barrier layer at 500 °C. On the other hand, the Ta2N barrier fails at 700 °C by the interfacial reaction between Ta2N and Si substrate instead of the migration of Cu into the Si substrate. For the case of TaN, the barrier failure occurs by the migration of Cu into the Si substrate at 750 °C. It is also demonstrated that the diffusion barrier property is enhanced as the nitrogen concentration in the film is increased.

ISSN:1071-1023    

DOI:10.1116/1.588818

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The ionized physical vapor deposition technique is used to fill high aspect ratio trenches with copper. This technique allows directional filling of embedded features, known as damascene, by sputtering metal atoms into a high density plasma. Large metal‐atom ionized‐flux fractions are achievable (≊85%) leading to high directionality of deposition at the biased substrate. In this article, we report quantitative measurements of fill directionality of Cu using an inductively coupled plasma (ICP) high density source. Copper is deposited into fairly aggressive (depth/width ≤1.5) damascene trenches. Metal ion flux fractions are estimated from direct measurement of the trench step coverage and compared to simulation. Estimates of the Cu+/Ar+ density ratios are also made to understand the influence of applied ICP power and Cu atom density (magnetron power) on fill directionality. It is found that at high magnetron powers (high copper atom densities) the plasma becomes ‘‘copper rich,’’ where the flux of copper ions exceeds that of the argon ions. At low magnetron power and high ICP power, we find the trench fill to be highly directional. As magnetron power is increased, directionality suffers due to cooling of the plasma by higher copper atom flux.

ISSN:1071-1023    

DOI:10.1116/1.588819

出版商:American Vacuum Society    

年代:1996

数据来源: AIP