Semiconductor device having edge seal and method of making thereof without metal hard mask arcing
A conductive hard mask layer can be patterned with peripheral discrete openings. An anisotropic etch process can be performed to form peripheral discrete via cavities, which are subsequently expanded to form a continuous moat trench. An edge seal structure can be formed in the continuous moat trench. Alternatively, a conductive bridge structure may be formed prior to formation of a patterned conductive hard mask layer, and a moat trench can be formed around a periphery of the semiconductor die while the conductive bridge structure provides electrical connection between an inner portion and an outer portion of the conductive hard mask layer. The entire conductive hard mask layer can be electrically connected to a semiconductor substrate to reduce or prevent arcing during an anisotropic etch process that forms the peripheral discrete via cavities or the moat trench.
1 . A method of making a semiconductor structure, comprising:
forming a semiconductor die including semiconductor devices and a dielectric material portion over a semiconductor substrate, wherein the dielectric material portion laterally surrounds the semiconductor devices;
forming a conductive hard mask layer over the semiconductor devices and the dielectric material portion;
forming a set of peripheral discrete openings through the conductive hard mask layer along a periphery of the dielectric material portion;
forming a set of peripheral discrete via cavities through the dielectric material portion down to a top surface of the semiconductor substrate by performing an anisotropic etch process that etches a material of the dielectric material portion underneath the set of peripheral discrete openings, wherein the peripheral discrete via cavities are laterally spaced apart from each other by an unetched portion of the dielectric material portion;
forming a continuous moat trench that laterally surrounds an inner region of the dielectric material portion by isotropically expanding the set of peripheral discrete via cavities and merging the set of peripheral discrete via cavities into the continuous moat trench; and
forming a conductive edge seal structure by filling the continuous moat trench with at least one conductive material.
2 . The method of claim 1 , wherein:
sidewalls of the semiconductor die comprise sidewalls of the dielectric material portion that are exposed to a kerf region located between the semiconductor die and at least one of an edge of the semiconductor substrate or an additional semiconductor die located over the semiconductor substrate; and
a region of the dielectric material portion located between the continuous moat trench and the sidewalls of the semiconductor die is free of any semiconductor device.
3 . The method of claim 1 , wherein all sidewall surfaces of the set of peripheral discrete via cavities are dielectric surfaces.
4 . The method of claim 1 , further comprising forming a contact-level dielectric layer over the semiconductor devices and the dielectric material portion, wherein the set of peripheral discrete via cavities is formed through the contact-level dielectric layer.
5 . The method of claim 4 , further comprising:
forming a set of contact openings through the conductive hard mask layer within an area surrounded by the set of peripheral discrete openings; and
forming a set of contact via cavities through the set of contact openings and the contact-level dielectric layer down to top surfaces of electrically conductive nodes of the semiconductor devices by performing the anisotropic etch process, wherein the anisotropic etch process etches a material of the contact-level dielectric layer selective to the semiconductor devices.
6 . The method of claim 5 , wherein the semiconductor devices comprise:
an alternating stack of insulating layers and electrically conductive layers; and
memory opening fill structures located within memory openings that vertically extend through the alternating stack and comprising a respective vertical semiconductor channel and a respective vertical stack of memory elements.
7 . The method of claim 6 , wherein:
each of the memory opening fill structures comprises a NAND string;
the electrically conductive layers comprise word lines of the NAND strings; and
the electrically conductive nodes of the semiconductor devices comprise the word lines.
8 . The method of claim 1 , wherein a maximum nearest neighbor distance within the peripheral discrete via cavities is less than a maximum lateral dimension of each peripheral discrete via cavity within the set of peripheral discrete via cavities.
9 . The method of claim 1 , wherein the continuous moat trench comprises:
a laterally-undulating outer sidewall having horizontally-concave outer surface segments that are adjoined to each other; and
a laterally-undulating inner sidewall having horizontally-concave inner surface segments that are adjoined to each other.
10 . The method of claim 1 , wherein the conductive hard mask layer continuously extends over sidewalls of the dielectric material portion and contacts a segment of a top surface of the semiconductor substrate located in a kerf region that is located between the semiconductor die and at least one of an edge of the semiconductor substrate or an additional semiconductor die located on the semiconductor substrate.
11 . The method of claim 10 , wherein each point within the conductive hard mask layer is electrically connected to a surface the segment of the top surface of the semiconductor substrate through a respective electrically conductor path located entirely within the conductive hard mask layer.
12 . The method of claim 1 , further comprising removing the conductive hard mask layer prior to, during or after formation of the conductive edge seal structure.