| 摘要 |
A method of forming a contact between a bit line and a local interconnect in a flash memory device comprises forming a hard mask layer on a planarized surface that includes an exposed top section of the local interconnects prior to depositing an oxide dielectric layer (Figure 8B,14). The hard mask layer may be composed of a material which has an etch resistance as compared to the interlayer dielectric material, e.g., nitride. Openings (Figure 8,68) in the hard mask define positions for the contacts to the local interconnects exposed in the top section. An etch mask (Figure 7,63) is further formed upon the interlayer dielectric 61 in order to define bit line trenches. An, e.g., anisotropic etching of the interlayer dielectric is performed down to the top section of the local interconnect through the hard mask opening, wherein the contact is established only through an overlap portion of openings in both the hard mask and the etch mask layers. In particular, the bit line trenches thus formed have a uniform width and interspacing to neighboring bit lines as contact holes may form only beneath the etch mask openings which define the bit lines. |
