Chemical Properties of Polymer Films Formed during the Etching of Aluminum in CCl4 Plasmas

Plasma etching characteristics of tungsten films are studied in CF4 and in SF6 discharges. The etch rates are investigated as a function of electrode temperature, oxygen and hydrogen additions, system pressure, and RF power. Relative fluorine atom concentrations are determined by optical emission spectroscopy. Results indicate that tungsten etching is primarily controlled by fluorine atoms generated in the discharge in CF4 plasmas or when oxygen is added to the etch gases. In pure SF6 , SFx species may play an important role in the etch process. Hydrogen additions scavenge fluorine atoms and generate residues which inhibit etching.

Section: Hydrogen Additions~hydrogen Additions To Cf4supporting

confidence: 93%

Tungsten Etching in CF 4 and SF 6 Discharges

Tang

Hess

1984

“…The metal etch rate data are complicated by polymerization phenomena, even at these low pressures (18). At low temperature, the etch rate falls in a manner analogous to that observed for BCIJCI~, as shown in Fig.…”

Section: Resultsmentioning

confidence: 60%

“…As discussed previously, when pure CC14 is used as the aluminum etch gas, polymerization can occur whenever the gas phase is depleted of C1 or CI=, species relative to CCI~ polymer precursors (13,18). The addition of CI~ to the feed gas can shift the balance of gas phase species in favor of the etchants and thereby enhance the etch rate and prevent polymer formation.…”

Section: Resultsmentioning

confidence: 96%

The Effect of Temperature and Flow Rate on Aluminum Etch Rates in RF Plasmas

Danner

Hess

1986

The effect of sample temperature and etch gas flow rate on the etching of aluminum in BCl3/Cl2 and CCl4/Cl2 mixtures in a parallel‐plate plasma etcher was investigated. Through the use of a thermally conductive epoxy to ensure good heat‐transfer, sample heating due to exothermic chemical reactions and plasma heating was found to result in a temperature difference of more than 100°C between bonded and unbonded samples. Thus, considerable increases in etch rate were observed for the unbonded samples. Etch nonuniformities during both the inhibition period and metal etching were studied, using different plasma conditions and a nozzle to deliver chlorine directly to the aluminum surface. Oxide etching depended upon ion flux and/or energy and upon the concentration of BClx or CClx . species, while Cl2 concentration at the sample surface determined the relative aluminum etch rates across the aluminum sample.

“…Indeed not a negligible amount of nitrogen is detected in this film, and there is a difference in the O and C1 content. The formation of carbon-rich films during plasma etching with C containing gases is widely reported (16)(17)(18); in our case we do not use C containing gases so that the source for the carbon is the photoresist (19).…”

Section: Resultsmentioning

confidence: 97%

Surface Characterization of the Al/Si‐Ti/W Metallization after Chlorinated Plasma Treatments

Torrisi

Vasquez

Viscuso

et al. 1991

Multilayer metallizations play a very important role as interconnection systems in the VLSI technology. Here, to realize etching with good dimensional control and vertical profile, plasma etchers (of the RIE type) are used. The complexity of the chemistry involved in this plasma etching is such that it may give rise to some undesirable secondary effects. The object of this work is the surface characterization, by means of XPS, SEM, and EDAX techniques, of the A1/Si-Ti/W system after plasma etching. The chemical modifications induced by various plasma treatments of the metal films have been followed by means of the above techniques. Such modifications are dependent either on the etch chemistry used or on the substrate chemical species exposed to the plasma.Very large scale integration (VLSI) technology requires increasing the chip size and decreasing the minimum feature size. This objective is achieved by continuous developments in lithographic and etching techniques and by improvements in materials technology. The materials used for the interconnections can be metals, heavily doped polysilicon, and metal polycides. In general the main properties required for these materials are: low resistivity, good chemical and high temperature resistance, good barrier properties, low contact resistance, good step coverage, resistance to electromigration, and ease of patterning.Aluminum is the most widely used metal for interconnections in integrated circuits thanks to its many good properties such as low resistivity, excellent substrate adhesion, and ease of deposition and patterning. At the same time, aluminum has some important limitations: bad temperature resistance, hillock formation, and moreover it has the tendency to interact with silicon causing the "spikes" problem (spikes can penetrate into the silicon and cause shorts). In order to avoid this phenomenon, Al-alloy (1) is currently employed. A1/Si alloy reduces the silicon diffusion problem, but the possible precipitation of silicon at the metal-silicon interface after the alloy thermal process causes an increase in the contact resistance. A1/Si/Cu alloy has low resistivity and good resistance to electromigration, but it still has some problems: poor high-temperature resistance and hillock formation (as well as A1 and A1/Si) and, mainly, difficult patternability by dry etch for corrosion problems (2).In this context the use of refractory metals and their silicides represents an improvement, mainly in solving the contact problem. In general the refractory metals have higher resistivity than A1, but they have very good performances as the diffusion barrier between A1 and Si, and form at the same time good ohmic contacts and/or good Schottky contacts. Ti (3), W (4), and Ti/W (5) are among the most studied of these materials.Therefore a metallization that is constituted of a layer of refractory metal on the contacts under a layer of an A1 alloy as interconnection material can be considered an excellent solution.Pattern definition for VLSI circuits requires the use of dry ...