Abstract: The current invention provides a method for analyzing process variations that occur during integrated circuit fabrication. Critical dimension data is collected for each layer of the integrated circuit fabrication process for a period of time and a shift indicator that indicates variation in the critical dimension data for each layer of the integrated circuit fabrication process is calculated. A machine drift significance indicator is also calculated for each machine used in each layer of the integrated circuit fabrication process, and a maximum shift of mean value for each layer of the integrated circuit fabrication process is defined. The shift indicator, the maximum shift of mean value and the machine drift significance indicator are used to determine at least one likely cause of variation in critical dimension for each layer of the integrated circuit fabrication process.

Abstract: A bubble detection system to detect bubbles in photoresist. The system includes photoresist at least one tank, a buffer tank, a pump, and a bubble sensor. The photoresist tank provides the photoresist. The buffer tank stores the photoresist from the photoresist tank. The pump pumps the photoresist from the buffer tank to an end terminal. The bubble sensor is set between the buffer tank and the pump to detect bubbles in the photoresist, and outputs an alarm signal when bubbles are detected. The nozzle is set at the end terminal to output the photoresist.

Abstract: A method for defining a dummy pattern around an alignment mark on a wafer. First, a wafer having an alignment area with an alignment mark is provided. Thereafter, lithography is performed on the wafer by a mask to define a first dummy pattern around the alignment mark in the alignment area. The mask includes a first dummy pattern area, with a first pattern to mask the alignment mark and a second pattern to define the first dummy pattern, and a second dummy pattern area, with a third pattern to define a second dummy pattern around the first dummy pattern.

Abstract: A method of deleting repeating defects having no effect on product yield of a wafer so that true defects on the wafer are more readily found. A wafer having a plurality of dies thereon is provided. The wafer is scanned to find any repeating defects. If the repeating defects have no effect on the product yield, the area around the repeating defects is marked out as “don't care” region. Another wafer scanning operation to find the true defects is subsequently conducted by scanning the region outside the “don't care” region.

Abstract: A bubble detection system to detect bubbles in photoresist. The system includes photoresist at least one tank, a buffer tank, a pump, and a bubble sensor. The photoresist tank provides the photoresist. The buffer tank stores the photoresist from the photoresist tank. The pump pumps the photoresist from the buffer tank to an end terminal. The bubble sensor is set between the buffer tank and the pump to detect bubbles in the photoresist, and outputs an alarm signal when bubbles are detected. The nozzle is set at the end terminal to output the photoresist.