Method of manufacturing flash memory

Abstract

The invention discloses a method of manufacturing a flash memory. The method comprises the steps of etching an active region and an isolation region on a semiconductor substrate which is stacked by a substrate, a sacrificial layer and a mask layer in sequence, forming a lining layer on the substrate after the etching of the mask layer and the sacrificial layer to obtain a semiconductor structure of a smooth corner; forming an insulation layer on the semiconductor structure of the smooth corner; forming an isolation oxide layer on the insulation layer to fill the isolation region; removing the isolation oxide layer and the insulation layer partially until the isolation oxide layer levels with the insulation layer and the mask layer; removing the mask layer located on the active region to expose the sacrificial layer and the partial insulation layer which are in contact with the mask layer; removing the exposed sacrificial layer and the partial insulation layer to expose the substrate of the active region; and forming a tunnel oxide layer and a floating gate layer on the exposed substrate of the active region. The invention can prevent the tunnel oxide layer and the floating gate layer from being influenced by the isolation oxide of the isolation region, thereby improving the data holding characteristics of the flash memory.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a method for manufacturing a flash memory. Background technique [0002] Flash memory is not easy to lose and can be repeatedly erased and read and written. In addition, it also has the characteristics of fast transmission speed and low power consumption, which makes flash memory widely used in portable products, information, communication and consumer electronics products. . [0003] In flash memory, data retention performance (Data Retention) is an important performance index. In order to improve data retention performance, in-situ steam generation (In-Situ Steam Generation, referred to as ISSG) is generally used in the prior art to form liners at the trench boundaries. Oxide, the purpose is to make the corner of the channel boundary rounded (cornerrounding) to ensure the tunnel oxide thickness and insulation performance at the edge of the channel, and to prevent the...

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Problems solved by technology

[0003] In flash memory, data retention performance (Data Retention) is an important performance index. In order to improve data retention performance, in-situ steam generation (In-Situ Steam Generation, referred to as ISSG) is generally used in the prior art to form liners at the trench boundaries. Oxide, the purpose is to make the corner of the channel boundary rounded (cornerrounding) to ensure the tunnel oxide thickness and insulation performance at the edge of the channel, and to prevent the tip discharge from causing breakdown or performance damage to the flash memory device, but in the subsequent Due to the influence of the isolation oxide in the process, it is difficult to guarantee the performance of the tunnel oxide and pad oxide, thereby reducing the data retention characteristics of the flash memory

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