Oxide CMP 에서 Slurry 특성이 Scratch 생성에 미치는 영향

Abstract

As the technology node is gradually decreased, CMP process is important to semiconductor process. However, CMP process generates inevitably defects such as scratch and pit. These scratches diminish the reliability and endurance of the surface. Therefore it is important to reduce the scratch and reveal the cause to generate the scratch. In this work, the effect of slurry factor on generating the scratch was studied. To analyze the scratches, the post CMP cleaning process was developed for 8inch oxide CMP process. To evaluate the effect of the type of abrasive particle, four type of abrasive particles; two type of fumed silica, colloidal silica and synthetic silica particle were used. Among these, synthetic silica based slurry produced very low number of scratches, but delivered very poor removal rate. Fumed and colloidal silica based slurry generated chatter type scratch but the synthetic silica based slurry generated the line type scratch. Three types of slurries which contained with the different pH adjusters (Chemical A, B and C) were evaluated to study their effect on scratch formation. It was found that the pH adjust chemicals did not show any affect on generating the scratches. All type of chemical slurry generated the chatter type scratch and the total numbers of scratches formed were almost same. To evaluate the effect of large particles in slurry, slurries which were filtered and not filtered with 0.5 ?m filter were used. No filtering slurry generated more scratches than filtering slurry. During CMP process, the used slurry was gathered by using vacuum suction system. The slurry by products was analyzed using the particle size analyzer and SEM. During CMP the pad particle was generated and this pad particle was confirmed from the SEM image and particle size analyzer. After the CMP process the size of fumed silica particle was shifted to smaller size. Finally it is concluded that the pad particle generated during CMP affected to generated scratches and the chatter type scratch was generated due to breaking the abrasive particle by mechanical force.