A kind of manufacturing method of flash memory

Abstract

The invention discloses a method for manufacturing a flash memory, which comprises etching an active region and an isolation region on a semiconductor substrate, wherein the semiconductor substrate is formed by stacking a substrate, a sacrificial layer and a mask layer in sequence, and the mask is etched back after the semiconductor substrate is sequentially stacked. A liner layer is formed on the substrate after the sacrificial layer is etched to obtain a semiconductor structure with rounded corners, an insulating layer is formed on the semiconductor structure with rounded corners, an isolation oxide layer is formed on the insulating layer to fill the isolation region, and part of Remove the isolation oxide layer and insulating layer until the isolation oxide layer and the insulating layer are flush with the mask layer, remove the mask layer located in the active area, expose the sacrificial layer and part of the insulating layer in contact with the mask layer, remove The exposed sacrificial layer and part of the insulating layer expose the substrate of the active region, and a tunnel oxide layer and a floating gate layer are sequentially formed on the exposed substrate of the active region. The present invention can prevent the isolation oxide of the isolation region from affecting the tunnel oxide and the pad layer, thereby improving the data retention 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 on the channel boundary The purpose of forming a pad oxide is to make the corner of the channel boundary rounded (cornerrounding) to ensure the thickness and insulation performance of the tunnel oxide at the edge of the channel, and to preve...

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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 on the channel boundary The purpose of forming a pad oxide is to make the corner of the channel boundary rounded (cornerrounding) to ensure the thickness and insulation performance of the tunnel oxide at the edge of the channel, and to prevent the tip discharge from causing breakdown or performance damage to the flash memory device. However, due to the influence of the isolation oxide in the subsequent 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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