Semiconductor structure and method of manufacturing the same
A semiconductor structure and a method of manufacturing the same are provided. The semiconductor structure includes a stack including first conductive layers and first dielectric layers, a second conductive layer formed on the stack, openings through the second conductive layer and the stack, and through structures formed in the openings, respectively. Each through structure includes a memory layer, a gate dielectric layer, a channel layer, a dielectric material and a pad. The channel layer is isolated from the stack by the memory layer, the channel layer is isolated from the second conductive layer by the gate dielectric layer, and the memory layer and the gate dielectric layer have different compositions.
1. A method of manufacturing a semiconductor structure, comprising:
forming a stack on a substrate, wherein the stack comprises a plurality of first layers and a plurality of second layers, the first layers and the second layers are alternately stacked, and a top second layer is thicker than other second layers;
forming a plurality of openings through the stack;
forming a plurality of memory layers on sidewalls of the openings, respectively;
forming a plurality of channel layers on the memory layers, respectively;
filling a dielectric material into the openings;
forming a plurality of conductive pads on the dielectric material in the openings, respectively;
removing portions of the memory layers that extend beyond the stack;
forming a plurality of gate dielectric layers on the channel layers, respectively; and
after forming the gate dielectric layers, forming a second conductive layer on the stack;
wherein the channel layers are isolated from the stack by the memory layers, the channel layers are isolated from the second conductive layer by the gate dielectric layers, and the memory layers and the gate dielectric layers have different compositions.
2. The method according to claim 1 , wherein in the step of forming the gate dielectric layers, the gate dielectric layers are formed by an oxidation process.
3. The method according to claim 1 , wherein a top surface of the dielectric material is at a level higher than a top surface of the stack.
4. The method according to claim 1 , wherein the step of removing the portions of the memory layers that extend beyond the stack comprises a nitride removing step and an oxide removing step, and a step of removing a hard mask on the stack and the nitride removing step are conducted simultaneously.
5. The method according to claim 1 , wherein in the step of removing the portions of the memory layers that extend beyond the stack, the portions of the memory layers that extend beyond the stack are completely removed.
6. The method according to claim 1 , wherein in the step of removing the portions of the memory layers that extend beyond the stack, a remaining nitride layer of the portions of the memory layers has a thickness less than 30 521.
7. The method according to claim 1 , wherein the memory layers have an ONO structure, an ONONO structure, an ONONONO structure or a SiON/SiN/oxide structure, and the gate dielectric layers are layers formed of oxide.
8. The method according to claim 1 , wherein in the step of forming the stack, the first layers are first conductive layers, and the second layers are first dielectric layers.
9. The method according to claim 1 ,
wherein in the step of forming the stack, the first layers are sacrificial layers, and the second layers are first dielectric layers; and
the method further comprises:
replacing the sacrificial layers by a conductive material so as to form a plurality of first conductive layers, wherein the first conductive layers and the first dielectric layers are alternately stacked.