Cleaning method after chemical mechanical polishing and chemical mechanical polishing method

Abstract

The invention provides a cleaning method used after chemical mechanical polishing of polycrystalline silicon and a chemical mechanical polishing method. The cleaning method used after the chemical mechanical polishing comprises a PVA (polyvinyl alcohol) scrubbing step, wherein the PVA scrubbing step comprises the following steps: first, soaking and flushing the surface of a wafer by using NH4OH (ammonia water); next, stopping soaking and flushing the wafer by using the NH4OH; and then, brushing the surface of the wafer by using a brush. The surface of the wafer is soaked and flushed by the NH4OH and then brushed by the brush, so that chemical separation and physical separation have the same cleaning effect and do not damage a natural oxide layer already formed on the surface of the wafer, thereby ensuring a relatively good uniformity of the natural oxide layer and avoiding influence on the nonuniformity of a next back etching process.

Description

technical field [0001] The present invention relates to a semiconductor manufacturing method, more specifically, the present invention relates to a cleaning method after chemical mechanical polishing and a chemical mechanical polishing method using the cleaning method after chemical mechanical polishing. Background technique [0002] For flash memory products, the source polysilicon will form a native oxide layer after chemical mechanical polishing. An etch-back of the source polysilicon can then be performed with a high selectivity to polysilicon and oxide, specifically about 30:1. Even a small change in the native oxide layer can greatly affect the amount of polysilicon etch back, resulting in critical dimension deviation. [0003] Generally, in the air at room temperature, the natural oxide layer on the polysilicon surface of the flash memory is formed very quickly, can easily reach saturation, and is very uniform. However, when the polysilicon surface of the flash memo...

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Problems solved by technology

[0008] like figure 1 As shown, in the above PVA scrubbing process, the NH 4 OH is sprayed on the wafer 1 to clean it while brushing the wafer 1 with the brush 2, because the chemical and physical processes act on the surface of the wafer 1 at the same time for the SIO 2 The removal rate of the brush 2 is much faster than that of pure chemical or physical processes; and the relative linear velocity of the brush 2 acting on each radial position on the surface of the wafer 1 is different, slow in the middle and fast at the edge, so the physical process acts on the wafer 1 The surface is uneven. This method will cause the thickness of the natural oxide layer on the surface of the wafer 1 to be uneven, thereby affecting the uniformity of the subsequent etch-back process.

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