Macronix International Co., Ltd.

Lien-Che Ho

Wei-Ming Chen

Chiu-Hua Chung

Ming-Yu Lin

Chun-Chieh Chen

Mao-I Ting

Kun-Yu Liu

Kung-Yi Chen

Shu-Ling Ku

A plurality of cells of a flash memory are tested to determine if they need to be refreshed. The cells are read and a plurality of different sensing ratios are used to determine if any of the cells need to be refreshed. Any cells that are determined to need refreshing are refreshed. The cells are read using only a single constant gate voltage.

Method for refreshing a flash memory

The present invention provides a method of producing an added defect count for monitoring the property of chambers or wafers. First, a proper pre-process sensitivity is determined with map to map process by maximizing the summation of a mapping rate and a catching rate. Second, a wafer is scanned with the proper pre-process sensitivity and a pre-process particle number P is recorded. Third, a manufacturing step is processed on the wafer. Fourth, the wafer is scanned with the most sensitive scale of the post-process sensitivities and a post-process particle number P is recorded. Finally, the post-process particle number P is subtracted from the pre-process particle number P .

Method of calculating the real added defect counts

In a method to verify a mask for a mask ROM, a serial of random codes that are exclusive to each other are implanted into a plurality of wafers manufactured by a same process with the mask or a plurality of die regions in a single wafer manufactured by a same process with the mask, and then the test results derived from the implanted wafers or die regions are compared to determine if the mask is defective.

Method of verifying a mask for a mask ROM

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 &ldquo;don't care&rdquo; region. Another wafer scanning operation to find the true defects is subsequently conducted by scanning the region outside the &ldquo;don't care&rdquo; region.

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Hsinchu, Taiwan

Lien-Che Ho