Formation method of semiconductor structure

Abstract

The present invention provides a method for forming a semiconductor structure. The method comprises a step of providing a substrate, a step of orderly forming a buffer layer, a first insulating layer and a hard mask layer on the substrate, a step of etching the first insulating layer, the buffer layer and the substrate with the hard mask layer as a mask, and forming grooves in the substrate, the buffer layer, the first insulating layer and the hard mask layer, a step of filling an electrode material layer in the grooves to cover the surface of the hard mask layer, a step of carrying out chemical mechanical polishing on the electrode material layer and hard mask layer, removing the electrode material layer on the hard mask layer, and forming an electrode layer in the remaining electrode material layer in the grooves. According to the method, firstly the grooves are filled with the electrode material layer, and then the chemical mechanical polishing of the electrode material layer and the hard mask layer are carried out. The buffer layer is not affected substantially by the chemical mechanical polishing. After the electrode layer is formed, the good shape of the buffer layer is maintained, and thus the semiconductor capacitor formed by the invention has good performance.

Description

Technical field The invention relates to the field of semiconductors, in particular to a method for forming a semiconductor structure. Background technique CMOS image sensor is a common semiconductor sensor on the market, widely used in mobile phones, tablet computers, fingerprint recognition and other fields. The use of 3D IC technology to make CMOS image sensors has become a research focus in this field. Using 3D IC technology to make CMOS image sensors, semiconductor capacitors need to be formed in the bottom wafer. Generally, the electrode plates of semiconductor capacitors are formed in deep trenches in the substrate. Please refer to FIG. 1 and FIG. 2, which are schematic diagrams of a manufacturing method of a semiconductor capacitor in the prior art. First, referring to FIG. 1, the substrate 01 is a doped active substrate, and a buffer layer 02, an insulating layer 03, and a hard mask layer 04 are formed on the substrate 01. The insulating layer 03 is used to protect...

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Problems solved by technology

However, in the process of removing the hard mask layer 04, the groove 05 exposes the sidewall of the buffer layer 02, and the buffer layer 02 is also easily eroded, so that the sidewall of the groove 05 is formed as shown in the circle. gap

After the electrode layer is formed in the groove 05, the electrode layer is also formed in the gap, causing the electrode layer to have uneven defects at the gap position, which may affect the capacitance value between the electrode plates, and even cause the electrode plate to be disconnected. , at the same time, it may also reduce the bonding between the substrate 01 and the insulating layer 03, causing defects in the semiconductor capacitor

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