Method for making flash memory

Abstract

The invention provides a method for making a flash memory. The method comprises the following steps: forming a tunneling oxidation layer, a floating grid, an inter-grid medium layer and a control grid in turn on a semiconductor substrate; forming side walls on the two sides of the control grid and the floating grid; forming a source / drain in the semiconductor substrate on the two sides of the control grid and the floating grid; forming a silicide layer on the semiconductor substrate, wherein the silicide layer covers the control grid and the floating grid; etching the silicide layer by a dry etching method and defining a silicide blocking area; forming an inter-layer medium layer in a non-silicide blocking area, wherein a contact hole exposing out of the source / drain and the control grid is formed in the inter-layer medium layer; forming a diffusion blocking layer on the inner wall of the contact hole and filling conductive substances in the contact hole to form a conductive plug; and performing metal wiring to form the flash memory. The invention prevents cavity in the conductive substances filled in the contact hole and improves the electrical performance of the semiconductor device.

Description

technical field [0001] The invention relates to a manufacturing process of a semiconductor device, in particular to a manufacturing method of a flash memory. Background technique [0002] Flash memory is a type of non-volatile memory that can retain on-chip information even after the power supply is turned off; it is electrically erasable and reprogrammable in the system without requiring a special high voltage; flash memory has low cost , The characteristics of high density. [0003] The production process of the existing flash memory is as follows Figure 1 to Figure 4 shown. refer to figure 1 , a gate oxide layer 102 is formed on the semiconductor substrate 100 . A first conductive layer 104 is formed on the gate oxide layer 102. The material of the first conductive layer 104 is polysilicon, for example, and its forming method is, for example, low-pressure chemical vapor deposition (LPCVD); The inter-gate dielectric layer 106, because the flash memory requires that t...

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Problems solved by technology

[0008] In the prior art, in the process of forming the flash memory, the silicide layer outside the low-resistance area is removed by a mixed etching method of wet etching and dry etching, and the wet etching method is isotropic. Therefore, during the etching process, the bottom of the sidewall will be almost completely etched away, so that in the subsequent process of forming conductive plugs in the source / drain, the diffusion barrier layer on the inner wall of the contact hole will extend to the bottom of the sidewall, so that it is filled to the bottom of the sidewall. Voids are generated in the conductive material in the contact hole, causing open circuit phenomenon and affecting the electrical performance of semiconductor devices

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