Reactive ion etching induced corrosion of Al and Al-Cu films

Lee, Wen‐Yaung; Eldridge, J. M.; Schwartz, G. C.

doi:10.1063/1.329043

Cited by 65 publications

(20 citation statements)

References 11 publications

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“…These plasmas are often used in sequence with an 0 2 plasma that removes polymeric material and restores a layer of protective aluminum oxide. A thermal oxidation treatment at 300-350°C and 1-atm 0 2 [104] is yet another technique that was found to be effective in passivating Al. A thermal oxidation treatment at 300-350°C and 1-atm 0 2 [104] is yet another technique that was found to be effective in passivating Al.…”

Section: Postetch Corrosionmentioning

confidence: 99%

Reactive Ion Etching

Gorowitz

Saia

1984

Plasma Processing for VLSI

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Section: Postetch Corrosionmentioning

confidence: 99%

Reactive Ion Etching

Gorowitz

Saia

1984

Plasma Processing for VLSI

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“…1 with an overetch of 50% (which varies with topography as well as with the concentration and the distribution of copper in the film). 16 though this may seem to be a low etch ratio when compared to that for other plasma etching processes, it is typical of results obtained in IC production today and is unlikely to improve appreciably in the immediate future. For chips with high copper content in aluminum and perhaps also high aluminum deposition temperature (-400~ the overetch requirement is usually greater than 50%, possibly greater than 80%.…”

Section: Photoresist Issuesmentioning

confidence: 82%

“…During this process step, an oxide forms on the aluminum surface which helps to prevent corrosion of the aluminum lines. 16 In a conventional barrel reactor, this oxide is 20-30 A in thickness and is spectroscopically similar to native aluminum oxide. 4~ Experience has shown that after plasma etching of aluminum, it may be necessary to carry out a more elaborate stripping procedure than is required after other plasma etching processes.…”

Section: Postetch Treatmentmentioning

confidence: 98%

Plasma Etching of Aluminum Metallizations for Ultralarge Scale Integrated Circuits

Riley

1993

J. Electrochem. Soc.

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The metallizations which interconnect devices formed on silicon wafers have evolved from a single level of "broad" lines of aluminum to very narrow lines (<1 ~m in width), often more than two levels per chip. Whereas broad lines may be satisfactorily defined by solution or "wet" etching, narrow lines must be defined by plasma etching to maintain dimensional and profile control. Moreover, simple aluminum metallization has become complex, generally consisting of a composite of barrier and antirefiecting layers which sandwich the aluminum film. In addition, the aluminum film itself is probably "doped" with silicon and copper for solid solubility and electromigration considerations. Consequently, plasma etching of "aluminum" has become more complicated in the last few years. In this article, the issues confronting the process engineer in attempting to implement reliable metal etching processes are reviewed, emphasizing metallization layers employed for very advanced complementary metal oxide semiconductor integrated circuits.Although various metallizations (e.g., Ti-Pd-Au and TiPt-Au) 1 have been used to interconnect devices of early integrated circuits and other materials such as metal polycides 1 and tungsten 2 have been used as well, aluminum has remained the overwhelming material of choice for this function. This is because aluminum has low resistivity (<3 ~-cm at 20~ which translates into low circuit resistance) and, despite its relatively low melting point (660~ 3 is compatible with other materials used in chip fabrication (e.g., it adheres well to SiO2, may be readily etched selectively to SiQ, and acts as an etch stop for vias etched through SiO2). Overviews of the evolution of plasma etching of aluminum and other metals for integrated circuit (IC) applications, as IC technology has unfolded, are presented in other publications (e.g., Ref. 1,[4][5][6][7][8][9]. Typical Film StructuresAs devices and features have become smaller and chips have become larger, aluminum has continued to be the primary interconnecting material. However, the nature of aluminum metallization has changed rather dramatically. For example, junction spiking problems 1 which are a consequence of the solubility of silicon (from source/drain or polycrystalline silicon lines) in aluminum at high-temperature processing steps were initially circumvented by the addition of a few percent of silicon to sputtered aluminum) ~ Since aluminum is usually etched with chlorine containing plasmas, the addition of a small amount of silicon has no significant effect on the plasma etching of aluminum because St-C1 compounds are volatile under these processing conditions (e.g., SIC14, boiling point = 58~ A1C13, sublimation point = 178~ 3 A more satisfactory solution to this solubility problem has been devised by the insertion of a diffusion barrier metal layer between aluminum and the silicon substrate (see Fig. 1) which prevents migration of silicon into aluminum during normal thermal cycling n43 during fabrication. To date, the most effective barrier layer...

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“…Since the passivating native oxide film normally present on the aluminum surface has been removed during etching, chlorine species are left in contact with aluminum, ultimately causing corrosion. Further, carbon contamination and radiation damage caused by particle bombardment may enhance corrosion susceptibility (85). A water rinse or an oxygen plasma treatment after etching lowers the amount of chlorine left on the etched surfaces, but is not adequate to preclude corrosion.…”

Section: Introduction To Microlithographymentioning

confidence: 99%

“…A water rinse or an oxygen plasma treatment after etching lowers the amount of chlorine left on the etched surfaces, but is not adequate to preclude corrosion. Low temperature thermal oxidations in dry oxygen appear effective in restoring a passivating native aluminum oxide film (85). Another method of preventing post-etch corrosion is to expose the aluminum film to a fluorocarbon plasma (86).…”

Section: Introduction To Microlithographymentioning

confidence: 99%