| 摘要 |
PURPOSE:To prevent a wafer from being curved and to eliminate the need to adjust the focus of a foreign matter detection system at any time by forming an air suction area while dispersing plural air ports in the top surface of a rotary disk which sucks the wafer under negative pressure. CONSTITUTION:Air passages 40 and 42-48 are formed in the rotary disk 12 and air ports and concentrical grooves 52 for their communication are formed in the top surface to suck the wafer on the disk under negative pressure through the air ports 50 and grooves 52. An air injection port 54 is formed slantingly to inject air slantingly, thereby conveying the wafer as shown by an arrow 18. The air suction area is set inside the outermost peripheral groove 52 for a six inch wafer and inside the 2nd groove 52 counted from the outside by blocking the air ports 50 of the outer periphery for a five inch wafer, and a similar adjustment is made for a four inch wafer. Therefore, wafers of different size are sucked over the entire surface to prevent curvature from occurring, and one point of each wafer is put in focus to perform foreign matter detection with high precision. |
