A polishing pad plays an essential role in determining the chemical mechanical planarization (CMP) performance such as removal rate, planarization, and defectivity. Further, it is important for the polishing pad to maintain good CMP performance throughout its lifespan. In order to achieve high performance and durability, a hole-type pad was suggested as an alternative to the conventionally used pore-type pad. In this study, the effect of the hole density on the CMP performance was examined for a hole-type pad. Surface characterization of the hole-type pad showed that the hole density corresponded to the contact ratio between the pad and the wafer, and therefore, the contact characteristics could be controlled by a hole fabrication process. The experimental results showed that the number of holes play a key role in determining CMP performances. The removal rate decreased with an increase in the hole density. The level of dishing showed an increase with the hole density. The number of CMP scratches decreased at higher hole densities. Higher contact ratio and the presence of large particle trap sites explain the lower trend of the micro-scratch observed. An important advantage of the hole-type pad is that it retains the surface structure as CMP continues, which implies contact behavior is maintained.

Kim JC, et al. Corea, 2nd ed. Seoul: Ilchokak, 1999;109-26. 14Purpose: To report a case of keratitis caused by Acinetobacter baumannii and Candida parapsilosis in a patient using 0.5% levofloxacin and 0.1% fluorometholone for an extended period of time. Case summary: A 55-year-old male patient in the neurosurgery department with conjunctival injection and discharge in his left eye was consulted for ophthalmic evaluation and treatment. He was hospitalized in the state of akinetic mutism and given 0.5% levofloxacin and 0.1% fluorometholone for 2 years. On slit-lamp examination, a 3.5 × 4.5-mm dense stromal infiltrate with an overlying epithelial defect was observed. Corneal scraping culture revealed multidrug-resistant A. baumannii and C. parapsilosis. According to the susceptibility result, the patient was treated with topical 10% piperacillin/tazobactam and 0.125% amphotericin B hourly. The corneal ulcer healed gradually with corneal opacity remaining after 8 weeks of treatment. Conclusions:The authors of the present study report a case of treated multidrug-resistant A. baumannii and C. parapsilosis keratitis in a patient using topical antibiotics and steroid for an extended period of time.

To evaluate the efficacy, safety, and satisfaction of patients who underwent conductive keratoplasty (CK). Methods: CK was performed in 20 patients between April and December 2009. Surgeries were performed on the dominant eye with emmetropia as the postoperative goal and on the non-dominant eye with mild myopia as the postoperative goal. Patients' satisfaction, refractive change, and visual acuity were evaluated for at least 3 months after the surgery. Results: Preoperatively, the mean manifest refraction spherical equivalent (MRSE) of the non-dominant and dominant patient eyes was 0.56 ± 0.48 D and 0.88 ± 0.25 D, respectively. Postoperatively, the mean MRSE of the non-dominant and dominant patient eyes was-1.65 ± 0.56 D and-0.06 ± 0.36D at 1 month,-1.33 ± 0.40 D and 0.17 ± 0.37 D at 3 months, and-1.10 ± 0.44 D and 0.31 ± 0.33 D at 6 months, respectively, indicating significant effect regression. Eleven out of 20 patients (55%) were disappointed with the results of CK. Conclusions: Conductive keratoplasty led to significant regression of refractive effects during follow-up. Monovision with CK is suggested to be a temporary refractive procedure in patients with presbyopia.