Post chemical-mechanical polishing (CMP) cleaning method and CMP method

Abstract

The invention provides a post chemical-mechanical polishing (CMP) cleaning method for polysilicon and a CMP method. The post CMP cleaning method provided by the invention comprises the steps that firstly, in a megasonic cleaning step, an H2O2-rich SC1 solution in which the mass percentage of NH4OH is 2.8 plus / minus 0.2 percent and the mass percentage of H2O2 is 3.0 plus / minus 0.2 percent is utilized to conduct megasonic cleaning; and afterwards, in a subsequent polyvinyl alcohol (PVA) brush cleaning step, NH4OH (ammonia water) and deionized water (DIW) are utilized to clean a wafer and brush the surface of the wafer. According to the post CMP cleaning method, the high concentration SC1 solution (in which the NH4OH serves as an etching agent) is utilized to improve the etching efficiency of a natural oxide layer, so that a better cleaning effect can be achieved; meanwhile, the H2O2 with higher concentration in the SC1 solution is utilized to oxidize the polysilicon to form the oxide layer, so that the natural oxide layer of a certain thickness can be generated on the surface of the polysilicon while the better effect is achieved, an organic pollutant layer cannot be formed on the polysilicon in the subsequent brush cleaning process, and the growth of the natural oxide layer of the polysilicon in the air cannot be influenced by pollutants on the polysilicon.

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 grows very rapidly, is easy to reach saturation, and is very uniform. However, when the polysilicon surface of the flash memory i...

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Problems solved by technology

[0008] However, for cleaning after CMP of source polysilicon, NH 4 Wafers with OH or standard SCl will maintain a clean polysilicon surface, or only form a less oxide layer on the polysilicon surface, so that, in the subsequent PVA brush cleaning step, the organic contamination particles on the PVA brush can easily stick to the surface of the polysilicon. clean polysilicon surface, so it will cause recontamination

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