Deep trench planarization methods with different structures

Abstract

The invention discloses a method for flattening deep grooves with different structures. The method comprises the following steps of 1) depositing a barrier layer on a silicon substrate; 2) depositing a photoresist on the barrier layer, performing development, and etching the barrier layer to expose the silicon substrate in which a groove needs to be etched in the subsequent flow; 3) etching graphs of the deep grooves with different widths and depths on the silicon substrate; 4) filling the deep grooves of silicon by using selective epitaxial growth; 5) depositing a polycrystalline silicon buried layer on a silicon chip, wherein the polycrystalline silicon buried layer covers the surface of the whole silicon chip; 6) removing polycrystalline silicon above the barrier layer. The method has the advantages that 1) the barrier layer can be effectively protected, and a process window is added; 2) the process can be more accurately controlled in an end point detection mode by utilizing film conversion between the polycrystalline silicon and the barrier layer; 3) the surface appearance is uniform, the defects can be avoided, and the yield is improved.

Description

Technical field [0001] The present invention relates to a method for planarizing trenches in semiconductor integrated circuits, and in particular to a method for planarizing deep trenches with different structures. Background technique [0002] In today's semiconductor technology, deep trench structures are widely used. For example, as an isolation structure to isolate electronic devices with different operating voltages, and as a P-N junction in a super junction structure semiconductor device, it can achieve high breakdown voltage performance through charge balance in the depletion state. For the latter super junction metal oxide semiconductor field effect transistor (super junction MOS transistor), the method of etching and filling the deep trench during the manufacturing process is to grow an n-type epitaxial layer on an n+ type silicon substrate ( Monocrystalline silicon), then a deep trench is etched on the epitaxial layer, and then the deep trench is selectively filled wit...

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Problems solved by technology

[0004] For some deep trenches with different widths and corner structures, after selective epitaxy (such as figure 1 As shown), for deep trench structures with different widths, the polysilicon thickness above the mask layer will be quite different, which will cause great challenges and difficulties to the subsequent chemical mechanical polishing process, and it is easy to cause over-polishing or surface residues. Defects (such as figure 2 , 3 shown)

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