Grain Size Distribution at the Bottom Region in Very Narrow Cu Interconnects

• Published in: Denki kagaku oyobi kōgyō butsuri kagaku Vol. 84; no. 3; p. 151
• Main Authors: INAMI, Takashi, TAMAHASHI, Kunihiro, NAMEKAWA, Takashi, CHIBA, Akio, ONUKI, Jin
• Format: Journal Article
• Language: Japanese
• Published: 01.03.2016
• Subjects: CONNECTORS (ELECTRICAL); Copper; Crystals; CU; Diffraction; ELECTRICAL CONDUCTIVITY; Film thickness; Grain size; GRAIN SIZE AND SHAPE; Grains; Interconnections; Mean free path
• ISSN: 1344-3542
• DOI: 10.5796/electrochemistry.84.151

Crystal grain sizes less than 40 nm diameter, i.e., mean free path of an electron in Cu, in both the upper and bottom part of Cu interconnects with 70 nm width and 150 nm depth as a function of overburden Cu plated films with 150 nm, 300 nm and 450 nm thickness have been evaluated by X-ray diffraction method. In the upper part of the Cu interconnects, the frequency ratio of the crystal grains with less than 40 nm diameter was quite small and changed little in the Cu interconnects among overburden Cu films with different thickness. In the bottom part of the Cu interconnect, however, the frequency ratio of the crystal grain with less than 40 nm diameter was found to be very dependent on the thickness of overburden Cu films. The frequency ratio was about 20% at the overburden Cu film thickness of 150 nm, while the frequency ratio decreased to less than 2% at the overburden Cu film thickness of 450 nm. The resistivity of narrow Cu interconnects was found to increase with the increase of the frequency ratio of crystal grains less than 40 nm diameter at the bottom part of Cu interconnects.