摘要:

We useEVFLOW, a thin film thermal flow process simulator, to simulate the thermal flow of metal thin films in axisymmetric contacts/vias on patterned wafers, where two dimensional surface evolution is appropriate. The flow processes considered are (1) Al and Au thin film laser melting processes, for which process temperatures are higher than the metal melting points, and (2) conventional Al thermal anneal processes (400–550 °C). Surface tension induced mass transport in the flowing films is calculated by solving the Navier–Stokes and continuity equations for incompressible fluids. Our simulations of Au film profiles during laser melting process predict the experimentally observed trends in void formation and collapse with feature geometry and deposited film thickness. In laser melting processes, the void shrinks and vanishes, resulting in fully filled contacts and planarized metal surfaces. Al film evolution in the thermal anneal process is modeled using a surface layer melting model. The thickness of the liquidlike flowing layer is assumed to be 0.02 μm in this work. The trends in the formation of voids with feature geometry and deposited film thickness predicted byEVFLOWreflect experimental observations. Voids may form during the thermal anneal processes. The surface layer melting model as used in this work will not predict the collapse of voids.

ISSN:0734-211X    

DOI:10.1116/1.588995

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Ti/Si and TiSi2/Si diodes have been prepared by direct current (dc) sputtering and rapid thermal processing. TheirI–Vcharacteristics from 77 K up to 300 K have been analyzed using a nonlinear least squares method to fit the experimental data. All the experimental data have been fitted using two exponentially dependent currents and a series resistance. Two parameters are fitted for each current: a saturation current and an exponential parameter. As is discussed in the article, one current can be assigned to the thermoionic current, since the exponential parameter fits well to the theoretical valueq/kTand therefore a temperature independent Schottky barrier height can be calculated. The second current, which yields an exponential parameter independent of temperature, cannot be assigned to a mechanism of direct tunneling through the barrier. As a result, we have proposed a trap‐enhanced tunneling mechanism to explain this current.

ISSN:0734-211X    

DOI:10.1116/1.588996

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

A Ti/TiN bilayer deposited under anTi/AlSiCu/TiN interconnect is generally used at the contact level to stabilize the contact resistance of small diameter contacts as well as to prevent junction spiking during postdeposition anneals. An air break followed by a furnace or a RTP anneal is generally required after the deposition of the Ti/TiN bilayer to improve the barrier stability. This three step interconnect scheme results in a low net effective throughput process if the same metallization system is used twice or, alternatively, in a high cost‐of‐ownership process if two metallization systems are used, a first for the Ti/TiN barrier and a second for theTi/AlSiCu/TiN interconnect. In this article, it is shown that collimation permits the deposition of very thick TiN barriers at the bottom of high aspect ratio contacts which allows contact metallization integration in a single metallization system. In addition, it is found that the use of aTiglue layer between the barrier and the AlSiCu contact interconnect to promote the filling of these high aspect ratio contacts with Al alloys results in a yield loss ofn+andp+contact chains and therefore should be avoided. Finally, it is demonstrated that an integrated Ti/TiN/AlSiCu/TiN contact metallization with excellent electrical properties is possible with collimated TiN barriers.

ISSN:0734-211X    

DOI:10.1116/1.588997

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The stress and yield behavior of Al alloys, Al(Cu) and Al(SiCu), have been investigated using bending beam and x‐ray diffraction techniques, and the effect of passivation on the stress–temperature behavior of alloys is examined. A stress analysis of trilayer (SiO2/Al alloy film/Si) structure was formulated in order to deduce the stress of the confined metal films from bending beam measurements. The stress–temperature behavior of Al alloy films obtained from bending beam techniques was in agreement with that determined directly by x‐ray diffraction techniques. The grain structure and precipitate morphology of these alloy films were studied using transmission electron microscopes. Presence of passivation leads to a change in microstructure of Al alloys, resulting in hardening for the Al(SiCu) films and softening for the Al(Cu) films when compared with the unpassivated films at room temperature. Our results reveal that oxide thickness, Al thickness, and microstructure play an important role in determining the plastic deformation behavior of the metal films, and can satisfactorily explain the contrasting behavior observed for Al(SiCu) and Al(Cu) films.

ISSN:0734-211X    

DOI:10.1116/1.588998

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Effects of insulator surface roughness on the overlying aluminum alloy film properties and electromigration performance in Al alloy/Ti insulator layered interconnects have been investigated. Insulator surface roughness changes the roughness and crystallographic orientation of Al/Ti layered films formed on the insulator. In particular, the effect is prominent in the case of high‐temperature sputtering of Al alloy films. A rough insulator surface deteriorates the roughness and crystallographic orientation of the Al alloy film formed on the insulator, while a smooth insulator surface improves those properties. The insulator surface roughness does not change the roughness and crystallographic orientation of the Al alloy film without a Ti underlayer. Ti roughness and crystallographic orientation are improved on a very smooth surface insulator resulting in improvement in the roughness and crystallographic orientation of the Al alloy film formed on the Ti layer. As a result, the electromigration performance in Al/Ti layered interconnects changes according to the underlayer insulator surface roughness.

ISSN:0734-211X    

DOI:10.1116/1.588999

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Cross sectional scanning electron microscopy was used to study the dependence of gap fill capabilities in 0.25–2.0 μm wide Al–Cu metal gaps of DuPont fluorinated polyimide films on solid content, adhesion promoter, spin dwell time, and solvent spray. It was found that reduced solid content, application of adhesion promoter and solvent spray improve gap fill capabilities. However, these improvements are insignificant. Spin dwell time has little effect on gap fill.

ISSN:0734-211X    

DOI:10.1116/1.589000

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

The Si/SiO2interface formed by remote plasma enhanced chemical vapor deposition (RPECVD) at low temperature with SiH4/N2O or SiH4/N2O/Cl2was studied and compared with thermal oxidation. The interface of the CVD SiO2without chlorine addition is rougher than that with chlorine addition. But the surface roughness of CVD SiO2films increases with chlorine addition. The thermal oxidation induces strong interface strains, and the strains generated by the CVD SiO2without chlorine addition are stronger and are distributed more nonuniformly than those by the chlorinated SiO2. It is believed that chlorine addition during RPECVD affects the initial stages of deposition, and chlorine is combined with Si dangling bonds existing at the Si/SiO2interface through the formation of Si–Clxbonds. It was also found that with chlorine addition during RPECVD, the strained layer thickness, interface trap density, and suboxide density could be lowered significantly.

ISSN:0734-211X    

DOI:10.1116/1.589001

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

Silicon dioxide films were grown using an oxygen plasma generated by an electron cyclotron resonance (ECR) source at several low temperatures. The plasma oxidation rate was investigated by varying the growth parameters. The oxide thickness parabolically increases with microwave power but decreases with increasing pressure or flow rate. A complementary model of the Deal–Grove oxidation theory is suggested for the plasma oxidation, and kinetic parameters are compared with the other plasma and thermal oxidation cases. The diffusion rate constant in O2plasma oxidation at room temperature is enhanced up to the level of the diffusion rate in thermal oxidation and the reaction rate constant is much larger than the thermal oxidation case. This may imply that, due to oxygen atoms dissociated by the ECR plasma, plasma oxidation is related to the atomic diffusion through oxide layer and the atomic chemical reaction at the Si–SiO2interface. The high quality of the ultrathin oxide film was characterized with a breakdown field of 14.8 MeV/cm and an interfacial state density of 1.2×1010eV−1 cm−2.

ISSN:0734-211X    

DOI:10.1116/1.589002

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

We report the properties of silicon nitride films deposited by the electron cyclotron resonance remote plasma enhanced chemical vapor deposition method on Si substrates using SiH4and N2. The effects of nitrogen/silane gas ratio (R=N2/SiH4), electron cyclotron resonance power, substrate temperature, and H on growth, refractive index, chemical composition, and etch rate were investigated. Nominally stoichiometric Si3N4films were obtained with a refractive index of 1.9∼2.0 at a wavelength of 632.8 nm. The etch rate of the films in a buffered HF solution (7:1) was low (∼0.7 nm/min) and increased with increasing H2gas flow rate and decreasing substrate temperature during deposition. Fourier transform infrared spectroscopy and high temperature thermal evolution experiments showed very small amounts of H in the films. A leakage current less than 100 pA/cm2at a field of 2 MV/cm, a resistivity of ≳4×1017Ω cm, and breakdown strengths of 6–11 MV/cm at a current density of 1 μA/cm2were observed. These properties are comparable to those of Si3N4prepared by conventional high temperature (700 °C) chemical vapor deposition. The performance of GaAs‐based field‐effect‐transistors in switching and power applications can be enhanced substantially by employing a metal‐insulator‐semiconductor structure. By taking advantage of aninsituprocess approach, insulator‐GaAs structures were successfully gated with excellent interfacial properties.

ISSN:0734-211X    

DOI:10.1116/1.589003

出版商:American Vacuum Society    

年代:1996

数据来源: AIP

摘要:

A boron‐accumulated Si(100) surface with boron coverage up to 0.1 monolayer has been prepared by high‐temperature annealing of B‐doped Si samples. Scanning tunneling microscopy has been used to monitor the transformation in surface morphology and surface atomic structure induced by boron surface accumulation. The specific boron‐induced surface features have been elucidated and a model of their atomic structure has been proposed. On the boron‐accumulated surface epitaxial Si films with a thickness of 0.1–3.0 monolayers have been grown using solid phase epitaxy and molecular beam epitaxy. The results show that under appropriate growth conditions B surface segregation can be suppressed even on the atomic scale. The effect of boron induced features on the growth process has been discussed.

ISSN:0734-211X    

DOI:10.1116/1.589004

出版商:American Vacuum Society    

年代:1996

数据来源: AIP