摘要:

The sidewall profile of Si etched in BCl3/Cl2chemistry from a single‐wafer plasma reactor was found to depend on pressure, presence of resist, BCl3flow rate, and the addition of CHCl3. In a RIE type of single‐wafer plasma reactor, higher pressure and higher power density are used to achieve a higher etch rate. In this case features such as corner trenching, sidewall bowing, and tapering occur more frequently. The correlations between these features and the etch parameters are discussed with a particular emphasis on sidewall passivation effect.

ISSN:0734-211X    

DOI:10.1116/1.585024

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Tungsten patterning by reactive ion etching has been studied in batch and single‐wafer reactors using photoresist as the etch mask and a chemistry comprised of CHF3/O2with CF2Cl2. Tungsten etch rate and patterned profile were found to depend upon energetic ion levels and reactor loading, as well as on the basic reactor control parameters of power, pressure, and gas composition. Process conditions suitable for fine‐line anisotropic profile formation through a single layer of resist were demonstrated for the low‐pressure batch reactor. At the higher pressure and power density typical of the single‐wafer reactor, multistep processing was required to balance the competing reactions of etch and deposition of ‘‘polymer’’ in order to maintain process control.

ISSN:0734-211X    

DOI:10.1116/1.585025

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

We have investigated the etch rates, residual lattice damage, surface morphologies, and chemistries of InP, InGaAs, AlInAs, and GaAs plasma etched in electron cyclotron resonance (ECR) CH4/H2/Ar discharges. The etch rates of InP and InGaAs increase linearly with additional rf biasing of the substrate, and are approximately a factor of 2 faster than for GaAs. Under our conditions the etch rate of Al0.52Ga0.48As is very low (∼25 Å min−1) even for the addition of 100 V rf bias. In all of these materials the residual damage layer remaining after dry etching is very shallow (∼20 Å) as evidenced from Schottky barrier height and photoluminescence measurements combined with wet chemical etching. InP shows significant P depletion with the addition of rf biasing during the ECR etching while GaAs retains a near‐stoichiometric surface. Hydrogen passivation of shallow donors inn‐type GaAs occurs to a depth of ∼3000 Å during exposure to the CH4/H2/Ar discharge for long periods (60 min). The surface morphologies in the In‐based materials become roughened for etching with the addition of rf biasing while GaAs displays smooth, residue‐free surfaces under these conditions.

ISSN:0734-211X    

DOI:10.1116/1.585026

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

High rate (≤10 μm min−1) etching of GaAs, AlxGa1−xAs, and GaSb in Cl2/Ar or SiCl4/Ar discharges is reported. The etching was investigated as a function of discharge pressure, power density and composition, and changes in the etching rate of AlxGa1−xAs when SF6was added to the gas mixtures. Highly anisotropic etching was achieved with SiCl4for all materials, whereas a greater degree of chemical etching was evident with Cl2. Provided self‐biases were ≤50 V, excellent Schottky diode characteristics were exhibited by TiPtAu contacts on SiCl4or Cl2etched GaAs surfaces. Energetic‐ion bombardment caused carrier compensation up to 2200 Å from the surface inn‐type (1017cm−3) GaAs, with this depth being less for lower self‐biases. Photoluminescence decreases of 2–25 times were observed after reactive ion etching of GaAs for both types of discharge. Chlorine residues were typically present to a depth of<20 Å after etching, with cleaner surfaces obtained with SiCl4than with Cl2.

ISSN:0734-211X    

DOI:10.1116/1.585027

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

Alloyed Au–Ge/Ni and sintered Au/Pd/Ge and Au/Pd/Ni/Ge ohmic contacts were formed onn‐GaAs using scanned electron beam processing. Thermal aging studies at elevated temperatures in the range 150–500 °C reveal that sintered ohmic contacts have a much higher resistance to thermal degradation than conventionally alloyed Au–Ge/Ni contacts. Activation energy plots of failure time as a function of aging temperature indicate that sintered Au/Pd/Ni/Ge ohmic contacts have much longer operating life (∼106h for an eightfold increase in ρcat 300 K) than both alloyed Au–Ge/Ni and sintered Au/Pd/Ge ohmic contacts. Studies on the effects of polyimide and rf sputtered SiO2passivation layers on the stability of ohmic contacts reveal that polyimide surface passivated contacts exhibit better stability than those passivated with SiO2. From Arrhenius activation energy analysis, there is strong evidence to suggest that a single degradation mechanism is responsible for ohmic contact failure over the full range of aging temperatures from 150 to 500 °C.

ISSN:0734-211X    

DOI:10.1116/1.585028

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The formation of quasi‐one‐ and zero‐dimensional electron systems on InSb (111) by Schottky barriers has proven to be a very successful method. The lateral confinement underlying these structures is achieved by a metal grating deposited directly onto the surface of the semiconductor. A large number of metals, ranging from strongly reactive alloys like NiCr to less reactive metals like Au is used to study the formation of the lateral confining potential. The confining potentials are characterized by their intraband resonances using far‐infrared spectroscopy. Discussing our results we take advantage of previous results for the Schottky barrier formation.

ISSN:0734-211X    

DOI:10.1116/1.585029

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

The reaction of tantalum with silicon to form tantalum silicide has been studied using rapid electron beam annealing which gives well controlled time–temperature conditions. Tantalum layers were deposited on single crystal silicon substrates, and annealed at temperatures between 750 and 1100 °C for times ranging between 0.1 and 90 s. The films were studied using sheet resistance measurements, Auger electron spectroscopy depth profiling scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The diffusion of silicon into the tantalum film , and subsequent formation of a stable silicide, was investigated as a function of temperature and time of anneal. It was observed that at a peak temperature of 900 °C, lasting for a time of 0.1 s, only partial silicidation of the deposited tantalum layer had taken place. These conditions establish the minimum thermal processing requirement which must be met for complete silicide formation.

ISSN:0734-211X    

DOI:10.1116/1.585030

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

This paper describes a newly developed technique for repairing transparent defects on photomasks. After the uniform application of a thin transparent TiO2film on the entire mask, a noble metal is photodeposited locally on the mask from an aqueous plating solution. The rate of photodeposition, and thereby, the structure and adherence of the deposited metal, depend on the preparation conditions of the TiO2film, the composition of the plating solution and the incident light flux. These parameters can be selected in such a way that opaque metal metal pads can be deposited in sufficiently short illumination times (∼5 s). By means of laser projection through a variable rectangular aperture, it is possible to deposit rectangular metal pads with micron‐sized dimensions and sharp edges and corners in a controlled and reproducible way. Since deposition is induced photochemically, thermal broadening of the deposit does not occur. It is shown that the repair process meets the requirements with respect to spot definition, photolithography, mask cleaning, and laser trimming.

ISSN:0734-211X    

DOI:10.1116/1.584988

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

This paper reviews recent publications concerned with simplifying photolithographic techniques for image transfer into planarizing polyimide layers in very large scale integrated (VLSI) technology. The primary purpose of the reviewed papers is to reduce the complexity of the more commonly used trilayer technology. To achieve the same results conventionally obtained with a trilayer process, bilayer schemes are discussed, as well as techniques employing photosensitive polyimide. An attempt is made to assess the success of these techniques on the basis of the reported resolution capabilities. Because patterning and etching planarizing layers is still a dynamically growing technology at the present time, only tentative mechanisms can be suggested, and only in some cases.

ISSN:0734-211X    

DOI:10.1116/1.584989

出版商:American Vacuum Society    

年代:1990

数据来源: AIP

摘要:

A Clausing‐like integral equation is derived which applies to both low pressure chemical vapor deposition (CVD) and physical vapor deposition (PVD) in cylindrical contact holes; i.e., over the full range of sticking coefficient (0–1). A steady state assumption is implicit in the formulation. In the absence of film deposition, the flux to the surface is spatially uniform. Analytical expressions are presented for the initial deposition profiles for PVD (unity sticking coefficient). Numerical inversions of the integral equations provide initial deposition profiles for CVD (low sticking coefficients). Initial deposition profiles exhibit poor uniformity in PVD and high uniformity in CVD, in agreement with empirical evidence. The results provide a test for proposed Monte Carlo simulations which are based on the same assumptions.

ISSN:0734-211X    

DOI:10.1116/1.584990

出版商:American Vacuum Society    

年代:1990

数据来源: AIP