Three-dimensional flash memory device
View Patent ↗The present invention is directed to a memory device comprising a semiconductor block formed on a p-type semiconductor substrate with the semiconductor block having i number of n-type line regions extending along a first direction separated by i−1 number of p-type line regions along a second direction substantially perpendicular to the first direction; and a plurality of paired gate electrodes extending along the second direction with each pair of the paired gate electrodes formed adjacent to two opposite sides of the semiconductor block with a charge-trapping layer interposed therebetween, where i is an integer greater than or equal to two. The n-type line regions may function as sub-bit lines or sub-source lines or both. The p-type line regions may function as channel lines that allow current to flow vertically between two n-type line regions adjacent thereto. The memory device may further include a bit or source select unit.
1. A semiconductor memory device comprising:
a plurality of parallel semiconductor blocks separated along a first direction on a p-type semiconductor substrate, each of said semiconductor blocks having i number of n-type line regions extending along a second direction separated by i−1 number of p-type line regions along a third direction;
a plurality of first plate electrodes separated along said second direction, each of said first plate electrodes being perforated by said semiconductor blocks extending along said second direction; and
a charge-trapping layer formed between said semiconductor blocks and said plate electrodes,
wherein i is an integer greater than or equal to two; said first, second, and third directions are orthogonal to each other.
2. The semiconductor memory device of claim 1 , wherein said third direction is substantially orthogonal to surface of said p-type semiconductor substrate.
3. The semiconductor memory device of claim 1 , wherein each of said first plate electrodes being perforated by said semiconductor blocks has a portion formed above said semiconductor blocks that functions as a word line and portions formed between said semiconductor blocks that function as control gates.
4. The semiconductor memory device of claim 1 , wherein said n-type line regions function as sub-bit lines or sub-source lines or both.
5. The semiconductor memory device of claim 1 , wherein said p-type line regions function as channel lines that allow current to flow along said third direction between two n-type line regions adjacent thereto.
6. The semiconductor memory device of claim 1 , wherein said charge-trapping layer has a multilayer structure comprising silicon oxide/silicon nitride/silicon oxide (ONO) or aluminum oxide/silicon nitride/silicon oxide (ANO).
7. The semiconductor memory device of claim 1 , further including a plurality of bit select units with each of said bit select units comprising:
a bit terminal extending along said third direction;
i or i−1 number of bit leads coupled to said bit terminal; and
i or i−1 number of parallel pairs of bit select transistors, each pair of said bit select transistors being coupled to one of said n-type line regions at one end and one of said bit leads at the other end,
wherein each pair of said bit select transistors including a paired gate electrodes extending along said third direction and coupled to a bit select line extending along said first direction.
8. The semiconductor memory device of claim 1 , further including a plurality of source select units with each of said source select units comprising:
a source stud extending along said third direction;
i or i−1 number of source leads coupled to said source stud; and
i or i−1 number of parallel pairs of source select transistors, each pair of said source select transistors being coupled to one of said n-type line regions at one end and one of said source leads at the other end,
wherein each pair of said source select transistors includes a paired gate electrodes extending along said third direction and coupled to a source select line extending along said first direction.