Mask target and method for forming the same

Abstract

The invention provides an alignment mark and a forming method thereof. The method comprises the following steps: forming a field oxide layer, a grid polysilicon layer and a metal antemedium layer in sequence on a substrate; forming communicated trenches in sequence on the field oxide layer, the grid polysilicon layer and the metal antemedium layer; and taking the stacked multi-layer trenches as the alignment mark. The alignment mark and the forming method enable the trench depth of the alignment mark of the metal antemedium layer to be deepened, and enable the acquisition of optical signals of the alignment mark to be easier when photoetching is conducted, thereby solving the problem that the alignment precision is reduced or alignment can not be realized because the alignment mark is too shallow.

Description

technical field

[0001] The invention relates to the technical field of transistor manufacturing methods, in particular to a novel alignment mark of a contact window layer and a forming method thereof. Background technique

[0002] Ordinary contact window layer alignment marks are made on the active area of ​​the scribe line, and grooves are formed on the pre-metal dielectric layer to form alignment marks by photolithography and etching of the contact window layer. During photolithographic alignment of the metal layer on the crystal plane, the photolithographic alignment machine achieves the purpose of alignment by obtaining the optical signal of the alignment mark of the contact window layer. Such as figure 1 As shown, the formation of the alignment mark of the contact layer in the known technology is on the pre-metal dielectric layer 12 on the single crystal silicon substrate 11 in the dicing line region, and the photolithography and etching field metal pre-dielectric laye...

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