Takayuki Tsuchiya

Small diameter via filling electrodeposition by periodical reverse current

To enable low power consumption and the access speed increase, three dimensional packaging of semiconductor chips has been proposed. In particular, a high-aspect ratio through silicon via (TSV) allows short chip to chip interconnection. 4 μm diameter and aspect ratio of 7.5 via TSV has filled. The perfect via filling was achieved within 25 minutes with the increasing irev/|ion| ratios of periodic reverse pulse current waveform. In addition, we evaluated produced cuprous ion concentration during electrodeposition by using rotating ring disk electrode (RRDE). From the electrochemical measurement by RRDE, cuprous ion concentration on the reactive surface was markedly increasing with the increasing irev/|ion| ratios. At irev/|ion| ratio of large (irev/|ion| = 6.0), a large amount of cuprous ion concentration produces during copper dissolution by reverse current and cuprous ion remain at via bottom. High cuprous ion concentration at via bottom accelerates deposition at via bottom and achieve bottom up filling. In this study, we simulated Cu+ concentration profile by the numerical computation of fluid dynamics. The results will be compared with the electrodeposits profiles in the small diameter via.

3D interconnected technology by high speed copper electrodeposition using diallylamine levelers

High-speed copper electrodeposition is needed to optimize the TSV process with a high throughput. To inhibit electrodeposition on the top surface of the TSV, the ODT was microcontact-printed on the top surface. The ODT microcontact-printing effectively inhibits the copper electrodepositon on the top surface. With 1.0 ppm SDDACC, V-shapes were formed in the via cross sections and these shapes lead to bottom-up via filling [1]. Without micro-contact-printing, and with 1.5 ppm SDDACC, V-shapes were again formed in the via cross sections and these shapes lead to bottom-up via filling. We succeeded in filling 10 μm diameter and 70 μm deep vias within 35 minutes without micro-contact-printing. This was achieved by optimizing the SDDACC concentration with CVS measurements. The inhibition layer of the micro-contact-printing does not speed up the TSV electrodeposition. The most important factor to speed up the TSV electrodeposition is optimization of the additives.