摘要:

The response times of optical emission spectroscopy (OES) and mass spectrometry (MS) have been measured for plasma etching of III–V heterostructures. For the Ga optical emission signal at 417.2 nm, a response time as fast as 0.2 s was obtained. The minimum response time of the145AsCl+2partial pressure, measured by MS, was found to be 0.9 s. The saturation times of the optical emission signal and the partial pressure signal have been shown to be related to the residence time of etch gases by varying the total gas flow rate and the chamber pressure. Decreasing residence time by reducing the pressure from 6 to 2 mTorr and maintaining a constant flow rate caused the saturation time of the Ga emission signal at 417.2 nm to decrease from 7 to 3 min. The145AsCl+2partial pressure signal saturated before the Ga emission signal. Endpoint detection for etching an AlInAs emitter and stopping on a GaInAs base of a heterojunction bipolar transistor was studied. Algorithms which monitor the change in Ga emission intensity have been developed to automatically stop the emitter etch with ∼2 nm of the GaInAs base layer removed. Additionally, etching of GaInAs on an InP substrate was studied and the signal from OES detected the endpoint before the MS signal did due to the faster response time.

ISSN:0734-211X    

DOI:10.1116/1.588764

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

A novel, very simple technique for the direct adjustment of the slope of facets in a reactive ion etching process is presented. The etching process is performed by screening the sample partially with an aluminum shadow mask, which is located inside the dark space of the plasma. The sidewall angle of etched lines, defined by a pattern mask on the sample, depends strongly on the distance between the shadow mask and the sample. The investigations are carried out with a methane‐hydrogen plasma. The angle of inclination of the sidewalls can be varied in a controllable manner by more than 45°. This technique is well suited to fabricate 90° reflectors, which are necessary for three‐dimensional optical interconnects with planar waveguide structures. To analyze the optical quality of the etched mirror plane, the beam transformation was investigated by reflectivity measurements using a single aluminum‐evaporated mirror structure, which is illuminated by a focused laser beam at a wavelength of 633 nm.

ISSN:0734-211X    

DOI:10.1116/1.588765

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

A comparison was made of thin films of silicon dioxide deposited, at floating temperatures, using electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR PECVD) and distributed electron cyclotron resonance plasma enhanced chemical vapor deposition (DECR PECVD). The refractive index, composition, and chemical bonding of the plasma oxides were determined by null and spectroscopic ellipsometry, nuclear reaction analysis, and Fourier transform infrared spectroscopy and were compared with thermal oxides. The damaged layer at the Si/SiO2interface resulting from ECR and DECR techniques was evaluated by spectroscopic ellipsometry. Finally, high frequency and quasi‐static capacitance voltage characteristics and ramped current voltage measurements were performed to determine the electrical properties of the ECR and DECR deposited silicon oxide. Device quality SiO2thin films have been prepared using both deposition techniques: low interface state density [5×1010eV−1 cm−2(ECR) or 2.5×1010eV−1 cm−2(DECR)], and high critical field [5.2 MV/cm (ECR) or 6 MV/cm (DECR)]have been achieved.

ISSN:0734-211X    

DOI:10.1116/1.588766

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Assessments of WSixreactive‐ion etching in terms of the different CF4to O2flow rate ratio were characterized. Based upon the evaluations from etching rates, side‐wall profiles, surface roughness, and damages, we observed that the optimum etching condition was at a ratio of 10:1. The recovery of reactive‐ion‐etching‐treated GaAs damaged layers through the thermal treatment was also investigated as a function of the annealing temperatures and duration times. These parameter evaluations were for the purpose of achieving a high performance GaAs metal–semiconductor field‐effect transistor.

ISSN:0734-211X    

DOI:10.1116/1.588767

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

In this article, we report investigations on the effects of methane/hydrogen (CH4/H2) reactive ion etching (RIE) of InGaAs/InAlAs/InP heterostructure materials for high electron mobility transistors, and especially on the electrical properties of the InAlAs layer after dry recess etching of the InGaAs cap layer. The ion etching induced damages in the barrier layer InAlAs are evaluated by diode current–voltage and capacitance–voltage measurements and deep‐level transient spectroscopy (DLTS). TheI–Vdata indicate that RIE lowers the Schottky barrier height (φb) and increases the ideality factor. Using low pressure (10 mTorr) RIE processes, with various self‐bias voltages, shows that the use of low ion energy is necessary to get good Schottky contacts. Rapid thermal annealing at 400 °C is shown to induce a limited decrease of the dry etching induced defects. However, full recovery of the electrical properties is not achieved. A significant improvement of the Schottky diode electrical characteristics and DLTS spectra is observed after wet etching a 60 Å thick InAlAs layer before metal deposition, indicating that the main damages are concentrated within a short distance from the surface.

ISSN:0734-211X    

DOI:10.1116/1.588768

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

A simple Cl2/Ar plasma chemistry can provide smooth, high‐rate etching of InP, InAs, InGaAs, A1InAs, and InGaAsP at room temperature under conditions in which there is a balance between formation and sputter desorption of the normally involatile InCl3. When the neutral/ion ratio is either too high or too low, surface roughening is apparent due either to the presence of InCl3, or to preferential loss of the group V element. The etching has been investigated as a function of microwave power (600–1000 W), rf power (0–300 W), process pressure (1.5–10 mTorr), and Cl2:Ar ratio under electron cyclotron resonance conditions. Use of N2or H2, rather than Ar, as gas additives to the chlorine, did not produce smooth, stoichiometric etched surfaces.

ISSN:0734-211X    

DOI:10.1116/1.588769

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

A low‐pressure etching process for advanced aluminum metallization stacks was developed using a high‐density helical resonator plasma source (Prototech model ESRF 600) mounted on a Lucas Labs cluster tool. The metallization stacks consisted of a 300 Å TiN antireflection layer on 6000 Å of Al (1% Cu) with a 1000 Å TiN diffusion barrier and a 100 Å Ti film to enhance adhesion to the underlying SiO2. The features widths were as small as 0.45 μm. The films were etched using gas mixtures of Cl2/BCl3. The BCl3proved to be an important additive to reduce notching of the Al film at the interface between the Al and the top layer of TiN. Best feature profiles were obtained using 80–90 sccm Cl2and 10–20 sccm BCl3at the following reactor conditions: 2.0 mTorr, wafer platen temperatureT=0 °C, 100 W rf bias power, and 1500 W source power. More anisotropic profiles are obtained by either decreasing the wafer platen temperature or increasing the rf‐bias power. The photoresist is also stripped in the same process chamber using an oxygen plasma at 5 mTorr, 50 W rf‐bias power, and 1500 W source power at a chuck temperature of 25 °C. Extensive application of real‐time process diagnostics, including optical emission spectroscopy and full wafer interferometry, aided process development by identifying end points, etching rates, and etching rate uniformities.

ISSN:0734-211X    

DOI:10.1116/1.588770

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

In this article, we report our results using the aluminum/germanium eutectic to create high quality patterned bonds between two silicon dice. The bonds are formed using thin metal layers and with essentially no pressure applied. We have measured bond strength by fabricating and bonding patterned dice. Pull tests were conducted and the force required to separate the bonds was measured and found to be about 1.6×107Pa. When bonds break, portions of the substrate are removed. Testing of the hermiticity of the bond demonstrated that leak rates below the detection limit of the leak tester (10−9sccs) are possible.

ISSN:0734-211X    

DOI:10.1116/1.588991

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

In very large scale integration metalization processes, thin diffusion barrier metal films deposited over vias and contacts are used to inhibit the diffusion of the top metal layer into the underlying junctions. These thin films are normally sputter deposited and their reliability is crucial to die yield and device lifetime. As wafer sizes increase, die at the wafer edge receive a directionally asymmetrical sputter flux, leading to nonuniform and asymmetrical film coverage over vias and contacts. Two three‐dimensional (3D) extensions of the two‐dimensional (2D) film growth programSIMBADare presented. The first extension (quasi‐3D) assumes a radially symmetrical adatom flux distribution and would be appropriate for the simulation of film deposition on regions near the central axis of a radially symmetrical target. Due to the assumption of a symmetrical flux distribution, the resulting film growth is symmetrical. The second extension (interpolated‐3D) does not assume that the flux is symmetrical and is intended for the simulation of asymmetrical film growth off‐axis. Both extensions provide a 3D surface of the deposited film and the microstructure and profile of 2D slices through the via or contact. In order to determine the accuracy of the two models, simulations were compared to W films sputter deposited over contacts having an aspect ratio of 3:1. The models were tested for a substrate placed directly under the center of the target. The interpolated‐3D model was also tested for asymmetrical fluxes by placing the substrate off‐axis by 2.2, 5.0, and 8.1 cm. The comparisons with the experimental results indicate that both the surface profiles and the microstructure of the deposited films were predicted well by the two models. The interpolated 3D model was very successful at predicting deposition profiles for off‐axis deposition flux.

ISSN:0734-211X    

DOI:10.1116/1.588992

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Electron beam deposition (EBD) provides an inexpensive way to fabricate nanostructures of various materials in a scanning electron microscope (SEM). However, the purity of metals deposited from an organometallic precursor gas is impaired by simultaneously deposited carbon coming both from the organometallic molecule and the residual contamination gas in the SEM chamber. We discuss carbon‐contamination EBD in a standard high‐vacuum SEM and compare it to EBD of Au in an environmental SEM (ESEM). The ESEM allowed us to perform ‘‘environmental’’ EBD (E‐EBD), i.e., EBD in the presence of an environmental gas (1–10 Torr) in addition to the organometallic precursor gas. We built a simple device that contains a reservoir for the organometallic precursor and goes on the sample stage of the ESEM. With this device we were able to highlight the advantages of E‐EBD over conventional, high‐vacuum EBD. We discuss the basic chemical reactions underlying the E‐EBD process.

ISSN:0734-211X    

DOI:10.1116/1.588994

出版商:American Vacuum Society    

年代:1996

数据来源: AIP