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Consumable of Chemical mechanical polishing (CMP) process for global planarization can be divided by pad, conditioner, and slurry. Wafer is applied to pressure on the pad with Slurry. Among the abrasives contained the slurry, although ceria has a low concentration, the removal rate is higher than the silica on inter-layer dielectric (ILD)/inter-metal dielectric (IMD) CMP process. Removal rate (RR) increased by Preston’s equation in proportion to the pressure and rpm (RR=KPV). Where K is a Preston’s constant, P is the main pressure, and V is the relative velocity. Yield improvement method in the semiconductor is a large uniform area after CMP process. In other words, wafer edge area should be minimized. It is important to control uniform pressure distribution. Head structure can be divided by main pressure for removal and retainer ring pressure for prevention out of course. In this research, pressure distribution is demonstrated by controlling the different pressure wafer pressure and retainer ring in a single pressure structure. Removal rate changed by different pressure due to pad deformation. Relative pressure difference changed from 150 to 30 g/cm2 to demonstrate for the reason. In case of the low pressure (1, 2psi), the smaller relative pressure difference increases the uniformity, but the removal rate is decreased. In the high pressure (3, 4 psi), the removal rate and uniformity are not big changes according to relative pressure difference. But parameters of temperature and coefficient of friction are not same. This research investigated the mechanism of how to affect the ceria in ILD/IMD CMP through each parameter. Figure 1. Removal rate according to relative pressure difference of retainer ring, (a) low pressure, and (b) high pressure. Figure 1

Ceria abrasive is widely used in the Inter layer dielectric (ILD) Chemical mechanical planarization (CMP) due to its high removal rate and high selectivity ability. Despite the relatively low hardness of the ceria, Ce-O-Si bonding between silicon oxide surface and ceria abrasive enables high removal rate of silicon oxide CMP. Therefore, it is important to investigate the Ce-O-Si bonding for further study of the post CMP cleaning as well as ceria CMP. In this study, the effect of the applied pressure on the ceria CMP was investigated. Dipping and polishing process was conducted to confirm the surface change with applied pressure. The Fourier-transform infrared spectroscopy was measured to compare between dipped wafer and polished wafer. Fig 1 showed FT-IR spectra of each samples. Bare wafer and dipped wafer show similar spectra. Meanwhile, polished wafer shows different spectra in the range of 1000-1200 cm-1 and 800-900cm-1 which were associate with the Si-O-SI and Si-O bonding. The intensity of the both peak decreased due to the Ce-O-Si bonding. Zeta potential is a key factor for adsorption behavior of the ceria CMP. Generally, ceria particle can adsorb on the silicon oxide surface due to electrostatic attraction with opposite zeta potential. however, adsorption phenomenon was different as function of the applied pressure. The applied pressure plays an important role in the adsorption behavior of ceria as well as the zeta potential. This research suggests the importance of the applied pressure for the ceria CMP process. Figure 1. FTIR spectra of the silicon oxide wafer in region of 600-1600 cm-1 Figure 1

Chemical mechanical polishing (CMP) is one of the process for planarization in semiconductor manufacturing. With the decrease of device size, copper (Cu) has been accepted as the material of interconnect for good performance. After electroplating process of Cu, overburden Cu surface is polished for planarization using CMP process. Generally, oxidants, dispersants, abrasive particles, chelating agents, and corrosion inhibitors are used in the Cu CMP slurry, and planarization of Cu is achieved by reaction of slurry components. Hydrogen peroxide is one of the oxidants which is widely used in Cu CMP slurry and react with Cu surface to form a passivation layer. In general, it is known that hydrogen peroxide is easily decomposed in the alkaline state. Therefore, in the alkaline slurry, decomposition of hydrogen peroxide can occur, which leads to deterioration of CMP performance. In this study, a new slurry injection method is proposed as an alternative to prevent the decomposition of hydrogen peroxide that may occur when hydrogen peroxide and slurry are mixed. The concentration of hydrogen peroxide decreased when hydrogen peroxide and slurry are mixed, and accordingly, the removal rate decreased (Fig. 1(a)). It indicates that hydrogen peroxide is decomposed in alkaline state, and this affects the CMP performance. In order to prevent the decomposition of hydrogen peroxide, hydrogen peroxide and slurry were separately injected (2-way injection) during the CMP process. Fig. 1(b) shows the comparison of the removal rate between the general method and the 2-way injection method in the slurry supply system. As shown in the graph, when using the 2-way injection method, the removal rate is almost similar to that of the general injection method. Therefore, the 2-way injection method can replace the general injection method. Figure 1. (a) the removal rate and concentration of hydrogen peroxide with slurry aging time, (b) the removal rate of general and 2-way injection method Figure 1