Semiconductor structure and preparation method thereof

Abstract

The invention relates to a semiconductor structure and a preparation method thereof. The method comprises the steps that: a substrate is provided, wherein a shallow trench isolation structure is formed in the substrate and is used for isolating a plurality of active regions which are arranged at intervals in the substrate; a patterned mask structure is formed on the substrate, wherein the patterned mask structure comprises a first mask layer and a second mask layer which are sequentially stacked upwards from the substrate; an etching process is carried out so as to enable the side wall of the first mask layer to be concave inwards; the substrate is patterned based on the patterned mask structure so as to form a bit line contact hole exposing the active region in the substrate; and a bit line contact structure is formed in the bit line contact hole. When a bit line contact material forming the bit line contact structure is formed, the recessed side wall of the first mask layer delays the 'sealing' time of the bit line contact material at the position of the first mask layer, so that no cavity or gap is formed in the bit line contact material (the bit line contact structure).

Description

technical field [0001] The present application relates to the technical field of integrated circuits, in particular to a semiconductor structure and a preparation method thereof. Background technique [0002] The mask pattern structure of a typical bit line contact hole is formed by stacking patterned mask layers composed of multiple layers of different materials. When depositing a bit line contact material layer in a bit line contact hole, the bit line contact material is different The deposition rate on the mask layer made of materials is different, and the bit line contact material will be "sealed" in advance in the middle of the bit line contact hole to form a bit line contact material layer with holes or gaps, and then a bit line contact material layer with holes or gaps will be obtained. Line contact structure, and the existence of voids or gaps will affect the resistance of the bit line contact structure, and then affect the conduction resistance of the bit line struc...

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Problems solved by technology

[0002] The mask pattern structure of a typical bit line contact hole is formed by stacking patterned mask layers composed of multiple layers of different materials. The deposition rate on the mask layer made of materials is different, and the bit line contact material will be "sealed" in advance in the middle of the bit line contact hole to form a bit line contact material layer with holes or gaps, and then a bit line contact material layer with holes or gaps will be obtained. Line contact structure, and the existence of voids or gaps will affect the resistance of the bit line contact structure, and then affect the conduction resistance of the bit line structure, how to eliminate the void or gap in the bit line contact structure has become an urgent problem to be solved

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