Minoru Takeuchi

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.

Single Diallylamine Type Copolymer Additive which Perfectly Fills Cu Electrodeposition with only 1ppm

Which Perfectly Fills Cu Electrodeposition with only 1ppm K.Kondo,M. Takeuchi, , H. Kuri, M. Bunya, N. Okamoto, T. Saito Department of Chemical Engineering, Graduate School of Engineering, Osaka Prefecture University, 1-1 Gakuen-Cho, Naka-Ku, Sakai-Shi, Osaka 599-8531, Japan Nittobo Medical Co., Ltd., 3-2-11, Kudankita, Chiyoda-Ku, Tokyo 102-8489, Japan E-mail: kkondo@chemeng.osakafu-u.ac.jp 1.Introduction. Cu via-filling is an essential technology for fabricating signal lines both on chip and on printed circuit boards and also through silicon via in 3-D wafer lever packaging. Generally four types of additives such as suppressors, accelerators, levelers and chloride ions are added to a Cu electrodeposition bath in order to achieve the bottom-up filling. The selections of additives and the control of additive concentration are complicated and cause in cost increase and poor quality control for Cu electrodeposition. In order to solve these problems, we succeeded to accomplish bottom-up filling by only single additive of 1ppm. This additive is a diallylmethylamine type copolymer, and it has cationic nitrogen and halogen ion and sulfur dioxide in copolymer structure. In this study, we synthesized various additive copolymers with anionic ions by radical polymerization in order to clear the mechanism of Cu filling process and function of ion structure in additives, and examined the interaction with cationic copolymers and anionic ions in process of Cu via-filling by electrochemical analyses and cross sectional observations. 2.Experimantal The Cu plating bath consists CuSO4 5H2O 130 g/L and H2SO4 200 g/L(1) and additives. The additives concentration is 1ppm. The deposition conditions are as follows; The current density was 10 mA/cm (galvanostatic electrolysis), the quantity of electricity was 14 C, the agitation speed was 1000 rpm (using magnetic stirrer), and the bath temperature was the room temperature. The additives are P(DAMAHCl/SO2) [diallylmethylamine hydrochloride and sulfur dioxide copolymer] and P(DAMAHBr/SO2) [diallylmethylamine hydrobromide and surfur dioxide], as shown in Fig. 1 3.Results The cross sectional shapes of Cu via-filling electrodeposition are shown in Fig.2. With P(DAMAHCl/SO2) and with P(DAMAHBr/SO2), the film thickness of the bottom of the microvia is thick, and that of the outsides of the microvia is thin. Therefore P(DAMAHCl/SO2) and P(DAMAHBr/SO2) suppress the deposition at the outsides and hence the deposition rate of the Cu deposited film at the bottom becomes thick. The potentials of the comparison of 10 rpm rotation speed and 1000 rpm rotation speed by RDE with P(DAMAHCl/SO2), P(DAMAHBr/SO2) were measured. It is suggested the condition with 10 rpm corresponds to the bottom of microvia and the condition with 1000 rpm corresponds to the outsides of microvia. The potential with P(DAMAHBr/SO2) is the smallest and the potential difference between 10 rpm and 1000 rpm is the largest. While, P(DAMAHCl/SO2), the potentials with 10 rpm and it with 1000 rpm have little difference. The adsorption model of these additive copolymers with halogen ions at microvia is shown in Fig.3. Without halogen ions such as P(DAMA/SO2), P(DAMAH2SO4/SO2) in Cu bath, the copolymers does not interact with electrode. However, with halogen ion the copolymers such as P(DAMAHCl/SO2), P(DAMAHBr/SO2) adsorb outsides of microvia. These copolymers have suppression effect for Cu deposition. The interaction of cationic additive copolymer and anionic halogen ion may introduce the suppression effect(1). (1)M. Yokoi, S. Konishi and T. Hayashi, Denki Kagaku oyobi Kogyo Butsuri Kagaku, 52, 218 (1984) a) b)