| CPC H10B 43/27 (2023.02) [H01L 21/28525 (2013.01); H01L 21/76805 (2013.01); H01L 21/76823 (2013.01); H01L 21/76834 (2013.01); H01L 21/76895 (2013.01); H01L 23/53271 (2013.01); H01L 23/535 (2013.01); H10B 41/27 (2023.02)] | 14 Claims |

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1. A vertical semiconductor device, comprising:
a lower stack including a source channel contact, wherein the source channel contact includes a first conductive layer and a second conductive layer;
an upper stack including a plurality of dielectric layers and a plurality of gate electrodes alternately stacked over the lower stack;
a channel layer penetrating the upper stack and extending in the lower stack, wherein the channel layer contact with the source channel contact; and
a barrier oxide formed on the first and second conductive layers of the source channel contact,
a vertical contact recess formed in the upper stack and extending to expose the barrier oxide; and
a sealing spacer formed on a side wall of the vertical contact recess and extending to cover the barrier oxide,
wherein the source channel contact includes a concave portion and a convex portion, the concave portion and the convex portion are directly contacted with the barrier oxide,
wherein the convex portion of the source channel contact has a peak, and the peak is provided by the second conductive layer, and
wherein the concave portion and the convex portion of the source channel contact are fully covered by the barrier oxide.
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