Jin-Goo Park

Effect of Poly Silicon Wettability on Polymeric Residue Contamination

The planarization has been implemented on the IC manufacturing such as a DRAM process including the shallow trench isolation (STI) and the self aligned memory cell contact pad (SAC) process. Poly silicon CMP has also been implemented to reduce the step height of gate poly Si in the construction of RCAT (recess channel array transistor) and FinFET three dimension structures. Poly silicon CMP uses either the same or similar pads or slurries as those for oxide CMP. Poly Si CMP is consecutively used in order to form self aligned memory cell contact pad [1]. The adhesion and removal rate of the polymeric residues was investigated as a function of wettability of the poly silicon surface during poly silicon CMP process. An oxidizer makes more hydrophilic poly silicon wafer surface and acts as a function of oxidant on the poly silicon surface in the DI water. Adhesion force between pad particle and poly silicon wafer decreased and saturated as a function of concentration of solution A, as an oxidizer. Figure 1 shows the contact angle of poly surface in the DI (Deionized) water as a function of concentration of solution A as an oxidizer. Contact angles of poly Si surface decreased from 69° to 23° as the concentration of solution A increases to 10 vol% and then reaches a constant value. A high contact angle indicates poor surface wetting while a low angle shows good wetting. The solution A acts as a surface oxidant on the poly Si surface and makes more hydrophilic surface in the DI water. The adhesion force of pad particle on the poly Si wafer surfaces was measured in the KOH solution (pH 11) as a function of solution A concentration. KOH was used for alkaline based slurry of poly silicon polishing and solution A was added in the KOH based solution in order to control the wettability of the poly silicon surface. Adhesion force decreased and saturated as a function of concentration of Solution A. When solution A was added to slurry, the poly silicon surface became hydrophilic due to oxidation reaction of silicon by Solution A. The change of surface wettability affects the order of contamination level on wafer because the interactions between particles and substrates are dependent on the wettability of the surface [2]. Figure 2 shows the changes of the contact angle of poly silicon in the alkaline silica based slurry solution as a function of solution A concentration. Complete wetting behavior was observed below 10° in the mixture solutions of the commercial alkaline based fumed oxide slurry and solution A. However, the only KOH based solution was not sufficient to make complete wetting on the hydrophobic poly silicon surface as shown in Fig 2. The polymeric particle contamination on poly silicon surface wafer in the KOH solution as a function of solution A concentration as show in Fig. 3. In case of KOH solution, polymeric particle was contaminated on poly silicon surface. However, if added the solution A in KOH based solution that not generated the contaminated on poly silicon wafer surface. So, the control of poly silicon wettability during polishing could reduce the attraction force of organic particles thus leads to a lower organic defects after CMP. Much more pad particles with water marks were observed at hydrophobic poly silicon surface than hydrophilic. The mechanism of wettability and high adhesion force of hydrophobic surfaces indicates that the controlling of the wettability of wafer surface played an important role in the adhesion and remove force organic residues on the poly silicon surface. The control of poly silicon wettability during polishing could reduce the attraction force of organic particles thus leads to a lower organic defects after CMP.

Optimization of CO2 Gas Cluster Generation for Cleaning Application

cleaning application Hoomi Choi, Hojoong Kim, Deokjoo Yoon, Jong W. Lee, Bong-Kyun Kang, Min-Su Kim, Jin-Goo Park, Taesung Kim SKKU Advanced Institute of Nanotechnology (SAINT) School of Mechanical Engineering Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon, Gyeonggi, Korea R&D center, ZEUS Co.,Ltd., 163-1 Busan-dong, Osan, Gyeonggi, 447-050, Korea Department of Materials Engineering, Hanyang University, Ansan, 426-791, Korea

Nano Gas Cluster Dry Cleaning for Damage Free Particle Removal

This work has been partially supported by the Research Center for Integrated Human Sensing System and Post BK21 program. Gas cluster cleaning system was supported by Zeus Co.LTD, Korea

Reevaluation of Hydrogen Gas Dissolved Cleaning Solutions in Single Wafer Megasonic Cleaning

The preparation of ultra clean silicon surface demands a higher level surface conditioning and less damage/ etching of patterns and substrates. The conventional RCA cleaning chemicals have been applied in batch type cleaning process. As a result, not only the consumption of DI water and other chemicals is increased, but also the excessive material loss of surfaces is anticipated in nm thick device films. In order to resolve these critical issues, gas dissolved functional water has been proposed as an alternative cleaning chemical combined with MS (megasonic) effect for the particle removal due to its purity and much lower consumption of chemicals. Little specific gas and chemical added DI water as a new cleaning solution with MS was initially introduced by Ohmi et al (1). Later high concentration of H2-DI water cleaning was performed by Morita et al (2). It showed the excellent particle removal efficiency when it had been conducted with nozzle type MS. Toda et al (3) studied the effect of MS on radical activation in various gases dissolved cleaning solutions to examine its cleaning mechanism. However, these works had not clearly defined cleaning mechanism of hydrogen gas dissolved DI water with MS. In this study, we revisited the H2 gas added DI water to understand its cleaning mechanism by characterizing its half life time, material loss, roughness and particle removal efficiency (PRE) with and without the megasonic irradiation. For experiments, a commercial gas contactor (pHasor