Pulsed laser planarization of metal films for multilevel interconnects

Conference · Wed May 01 00:00:00 EDT 1985

OSTI ID:5536074

Tuckerman, D B; Schmitt, R L

Multilevel interconnect schemes for integrated circuits generally require one or more planarization steps, in order to maintain an acceptably flat topography for lithography and thin-film step coverage on the higher levels. Traditional approaches have involved planarization of the interlevel insulation (dielectric) layers, either by spin-on application (e.g., polyimide), or by reflow (e.g., phosphosilicate glass). We have pursued an alternative approach, in which each metal level is melted (hence planarized) using a pulsed laser prior to patterning. Short (approx.1 ..mu..s) pulses are used to preclude undesirable metallurgical reactions between the film, adhesion or barrier layer, and dielectric layer. Laser planarization of metals is particularly well suited to multilevel systems which include ground or power planes. Results are presented for planarization of gold films on SiO/sub 2/ dielectric layers using a flashlamp-pumped dye laser. The pulse duration is approx.1 ..mu..s, which allows the heat pulse to uniformly penetrate the gold while not penetrating substantially through the underlying SiO/sub 2/ (hence not perturbing the lower levels of metal). Excellent planarization of the gold films is achieved (less than 0.1 ..mu..m surface roughness, even starting with extreme topographic variations), as well as improved conductivity. To demonstrate the process, numerous planarized two-layer structures (transmission lines under a ground plane) were fabricated and characterized. 9 refs., 2 figs.

• Research Organization: Lawrence Livermore National Lab., CA (USA); Sandia National Labs., Livermore, CA (USA)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 5536074
• Report Number(s): UCRL-92257; CONF-8506123-2; ON: DE86012339
• Resource Relation: Conference: VLSI multilevel interconnection conference, Santa Clara, CA, USA, 24 Jun 1985; Other Information: Portions of this document are illegible in microfiche products
• Country of Publication: United States
• Language: English

Related Subjects

42 ENGINEERING
THIN FILMS
SURFACE TREATMENTS
DYE LASERS
EXPERIMENTAL DATA
GOLD
SILICON OXIDES
CHALCOGENIDES
DATA
ELEMENTS
FILMS
INFORMATION
LASERS
LIQUID LASERS
METALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
SILICON COMPOUNDS
TRANSITION ELEMENTS
420800* - Engineering- Electronic Circuits & Devices- (-1989)