Research of non-uniformity in 450 mm multi-electrode capacitive coupled plasma Gi Jung Park a, ⁎, Yoon Seong Lee a , Sang Hoon Seo a , Chin Wook Chung b , Hong Young Chang a a Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 305-701, South Korea b Department of Electrical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul, 133-791, South Korea abstract article info Available online 3 December 2012 Keywords: Large-area CCP Multi-electrode Uniformity To enable the industrial application of large-area capacitive coupled plasma (CCP), we studied non-uniformity of CCP with a 450 mm electrode. The field difference is one factor that reduces plasma uniformity. This effect is increased when the electrode's area is enlarged; therefore, we designed a multi-electrode CCP to overcome this problem. We found the optimal power conditions for each electrode to provide the best uniformity. Then, we powered on only one electrode to determine the property of each electrode. Our experiments showed some diffusion issues, and these results matched the results of the previous uniformity experiments. © 2012 Elsevier B.V. All rights reserved. 1. Introduction To meet future demands for a large-area process in the semiconduc- tor industry, there is a need for the development of the large-area ca- pacitive coupled plasma (CCP) sources to run the process [1,2]. In the industry, the defect ratio in manufacturing must be reduced to a mini- mum, and the ratio is known to be heavily related with plasma unifor- mity. Therefore, we concentrated on finding a way to achieve sufficient uniformity of our CCP sources. Many researchers have found that plasma generated from large- area sources is not uniform [3,4], and Lieberman calculated the non-uniformity with the field difference between the electrode's cen- ter and side [2]. To eliminate this effect, it seems that the area of plas- ma sources must be decreased. However, our goal is the development of the large-area CCP sources. Chabert [6] used a shaped electrode and a dielectric structure. This work is exceptional but this structure is difficult to apply with industrial equipment. Instead, we adopted a multi-electrode concept illustrated by Monaghan [7]. We simulated the multi-electrode before realizing the concept. Finally, we deter- mined the shape of the multi-electrode, which is described in the next section. 2. Experimental details Our multi-electrode has two electrode segments. One is a circular electrode located at the center; the other is a ring-type electrode lo- cated at the side. The side electrode is wrapped around the center electrode. Between the two electrodes, a Teflon™ ring is inserted for insulation. Each electrode is connected with a copper feeding line. The center electrode is connected with one feeding line at the center; the side electrode is connected with four branches, and these branches are assembled at the center with a ring-type component. A side feeding line is connected with this component. Fig. 1 shows these structures. A metal shield is attached around the center electrode's feeding line to prevent interference between two feeding lines. This component is omitted in Fig. 1. The radius of the center electrode is 160 mm, the thickness of the Teflon™ ring is 5 mm, and the side electrode's inner and outer radii are 165 mm and 230 mm. Each feeding line is connected to one matching box and one power generator. Therefore, two matching boxes and two power generators are used when the sources are fully operated. The power generator of the center electrode emits an 8 MHz RF signal, and the power generator of the side electrode emits a 13.56 MHz RF signal. In the experiment, we don't operate our source fully because we want to investigate the effect of each electrode on the large area plasma. When one electrode is connected with the power generator, the other electrode is grounded or floated. We need to obtain data of the overall plasma to investigate the large-area plasma. This means we need many probes to be installed in the chamber. Therefore, the common Langmuir probe is not suitable. Instead of this probe, we adapt a special device called 2D probe array [8,9]. It has 29 circular probes in one circular board (diameter: 300 mm) which obtains plasma data using the floating harmonic meth- od [5]. After measurement, a controller collects data from each probe and provides the overall plasma data in a 2D graph. The data of points far from the probes is calculated automatically using extrapolation from the data obtained near the probes. Fig. 2 shows the installation of the 2D probe array. All measurements given in the next section are done in 13.3 Pa argon plasma. The radius of the chamber was 350 mm, the radius of the powered multi-electrode was 230 mm, and the radius of the grounded electrode is also 230 mm. The gap between the powered electrode and the grounded electrode is 120 mm. The frequency of Thin Solid Films 547 (2013) 293–298 ⁎ Corresponding author. E-mail address: rootlog@kaist.ac.kr (G.J. Park). 0040-6090/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.tsf.2012.11.044 Contents lists available at ScienceDirect Thin Solid Films journal homepage: www.elsevier.com/locate/tsf