Preparation method for highly-doped phosphorosilicate glass film

Abstract

The invention discloses a preparation method for a highly-doped phosphorosilicate glass film. The preparation method includes the following steps: forming a gate oxide layer, a polycrystalline silicon gate and a side wall on a silicon substrate; injecting a drain source and carrying out rapid thermal annealing; depositing an SACAD PSG (Selected Area Chemical Vapor Deposition Phosphosilicate Glass) film; depositing an HDP PSG (High Density Polyethylene Phosphosilicate Glass) film; and etching a contact hole. According to the preparation method, the phenomenon that the silicon substrate is damaged by over etching of the contact hole can be avoided; and the PSG film prepared by the method has excellent hole-filling performance and a film structure easy to etch. During preparation, firstly, a layer of PSG film is grown by using an SACAD deposition process; and secondly, a highly-doped PSG film is grown by using an HDP CAD deposition process. Due to the utilization of the characteristic that the SACAD PSG film is uniform in the phosphor doping mount, the position of a starting point at the bottom of the HDP PSG film flower-shaped casing is heightened, a process window for selective etching of the contact hole is increased and further the phenomenon that the silicon substrate is damaged caused by the over etching of the contact hole and the performances of the devices are effectively maintained.

Description

technical field [0001] The invention relates to the field of semiconductor manufacturing, in particular to a method for preparing a highly doped phosphosilicate glass dielectric film. Background technique [0002] Dielectric films are widely used in semiconductor manufacturing processes. The commonly used dielectric materials mainly include non-doped silica glass (that is, pure silicon dioxide), phosphosilicate glass and borophosphosilicate glass. Phosphosilicate Glass (PSG) is silicon dioxide doped with phosphorus. Compared with pure silicon dioxide, the stress of the phosphosilicate glass film is small, and the doped phosphorus can also effectively fix impurity ions, so in IC It is often used as an insulator (PMD) dielectric film between the metal layer and the underlying polysilicon. [0003] There are many methods for preparing phosphosilicate glass films. Among them, the high-density plasma chemical vapor deposition (HDPCVD) process has become the most popular choice f...

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Problems solved by technology

However, the phosphosilicate glass prepared by the current HDP CVD process has a relatively low starting point at the bottom of the flower-shaped shell (the distance from the substrate is less than 50nm), so the switching point of the two-step self-aligned etching process is also very low. , it is possible to contact the substrate silicon during the low selectivity etching process, resulting in unnecessary silicon etching, such as figure 2 shown, this can cause damage to the device

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