Surface Photochemically Activated Chemical Vapor Deposition of Patterned Aluminum Thin Films
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SURFACE PHOTOCHEMICALLY ACTIVATED CHEMICAL VAPOR DEPOSITION OF PATTERNED ALUMINUM THIN FILMS
G. S. HIGASHI. G. E. BLONDER, and C. G. FLEMING AT&-T Bell Laboratories. 600 Mountain Ave. Murray Hill. N.J. 0707-1
ABSTRACT
KrF excimer laser (2-18 nm) images of mask patterns have been Iused to of activate tihe surface catalytic decomposition photochemically triisobutylaluminum (TIBA). The activation step is shown to involve the photolysis of organoaluminum surface adlayers leading to the formation of reactive Al sites. These sites serve to selectively nucleate the thermal decomposition of TIBA which results in the growth of high quality Al filns (resistivities -5 p0-cm). The growth on the chemically inert surfaces of SiO., and Al 20 3 is extremely selective and results in patterns with resolutions "-2pmn. To evaluate the utility of this process for real circuit applications, the laser activated deposition technique has been used in conjunction with standard photolithographic processing to fabricate metal-oxide field effect transistors and Al interconnects. The successful fabrication of working devices indicates that the laser activated deposition technique is compatible with standard photolithographic patterning schemes and may provide a means for simplifying integrated circuit fabrication.
Laser induced chemical vapor deposition of patterned thin films has m opened new avenues in integrated circuit fabrication..2lask repairl as well as the fabrication of discretionary interconnects2 have already been demon.strated and show early- promise. In these applications, the thin film pa1 ttertis are typically generated with a focussed laser beam to defile a reaction zone of microscopic dimensions. The wafer i, then translated tinder the laser to obtain the desired pattern. Intrinsically. such techniques are maskless andi so )'offer great flexibility. but since they are serial in nature writing speeds are ofl'en a major limitation. Despite writing speeds as high as a few millimeters/second. these processes seem suitable only for repair or for customizing circuits. VFor fNil wafer fabrication applications a parallel patterned exposure/deposition ifd1,rss is needed. This paper describes a projection patterned technique for the selective deposition of aluminum fihns, in a way that is compatibkle with conventional photolithographic processing. The first successful projection patterned metal deposition was performed by Yokoyama. Uesugi. Kishida and W\.ashio.3 Here. Cr was deposited using Cr(CO)6 as the precursor. In that work Cr features with edge definitions of better than 10 pm were deposited. The films, however, were highly resistive (p 5 X 10-3cl--m) and showed high concentrations of both C antdl 0. .Mat. Res. Soc. Symp. Proc. Vol. 75.
1987 Materials Research Society
118
Nevertheless, these films were opaque and highly adherent, and thus completely suitable for mask repair applications. For integrated circuit metallization applications high quality (i.e. smooth, low resistivity) patterned thin films are necessary. To work
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