Silicon chip etching method

Abstract

The invention discloses a method for etching a silicon wafer. In the method, the silicon wafer is etched by process gas, which lower layer is an oxide layer, and the process of etching the silicon wafer is detected by a laser detector. The laser detector transmits a laser beam to an etching slot on the silicon wafer and then the lower surface of the silicon wafer and the bottom of the etching slot respectively reflect one laser beam, and thus the depth of the etching slot is analyzed by the two reflected laser beams. When the etching depth closes to the upper surface of the oxide layer or when any part of the bottom of the slot formed by etching exposes the upper surface of the oxide layer, the content of oxygen in the process gas is increased with the flow rate of oxygen of 2-50sccm in order to protect the oxide layer. Later, the process of etching can be detected by a spectrum analyzer and also estimated according to the time by experience. The invention can not only fully etch the silicon wafer but also fully protect the oxide layer beneath the silicon wafer. And the invention is especially suitable for the etching of polysilicon besides the etching of other silicon wafers.

Description

technical field [0001] The invention relates to a semiconductor silicon chip processing technology, in particular to a silicon chip etching process. Background technique [0002] At present, microelectronic technology has entered the era of VLSI and system integration, and microelectronic technology has become the symbol and foundation of the entire information age. [0003] In microelectronics technology, to manufacture an integrated circuit, it needs to go through several processes such as integrated circuit design, mask manufacturing, raw material manufacturing, chip processing, packaging, and testing. In this process, etching the semiconductor silicon wafer to form process trenches is the key technology. [0004] Reactive plasma etching refers to the method of etching under the dual effects of physical bombardment and chemical reaction of active ions on the substrate. At present, the reactive plasma etching technology has become the most widely used mainstream etching ...

AI Technical Summary

Problems solved by technology

When using the OES (spectral analyzer) endpoint control mode, when the SiO2 oxide layer is engraved, the spectrum of the reactant will change. At this time, the supply of the reaction gas can be stopped to effectively protect the SiO2 oxide layer. When the spectrum changes, the SiO2 oxide layer is often etched, and in the process below 0.18um, the thickness of the SiO2 layer is very thin, usually less than 50A, and the layer is easily etched away

When using the time control mode, it is difficult to accurately control the etching time and depth of the polysilicon gate without damaging the SiO2 oxide layer by empirically estimating the etching time and depth.

[0008] Since PR contains carbon, it is easy to precipitate oxygen in silicon dioxide and react with it, thereby accelerating the etching speed of exposed silicon dioxide, resulting in poor etching uniformity, which easily causes the uniformity of the remaining SiO2 layer deteriorating, affecting final device performance

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