Nonvolatile semiconductor memory device
View Patent ↗A memory cell includes an ONO film composed of a stacked film of a silicon nitride film SIN which is a charge trapping portion and oxide films BOTOX and TOPOX positioned under and over the silicon nitride film, a memory gate electrode MG over the ONO film, a source region MS, and a drain region MD, and program or erase is performed by hot carrier injection in the memory cell. In the memory cell, a total concentration of N—H bonds and Si—H bonds contained in the silicon nitride film SIN is made to be 5×10 20 cm −3 or less.
1. A nonvolatile semiconductor memory device comprising:
a pair of source and drain regions formed in a semiconductor substrate;
a first gate electrode formed over a region of the semiconductor substrate between the source and drain regions; and
a charge trapping portion formed between a surface of the semiconductor substrate and the first gate electrode,
wherein the charge trapping portion includes a first nitride film and a second nitride film,
wherein, in the first nitride film, a total concentration of N—H bonds and Si—H bonds is 5×10 20 cm −3 or less,
wherein the second nitride film is formed directly on the first nitride film, and
wherein a program or erase is performed by hot carrier injection into the charge trapping portion.
2. The nonvolatile semiconductor memory device according to claim 1 ,
wherein a film thickness of the first nitride film is 3 nm or less.
3. The nonvolatile semiconductor memory device according to claim 1 ,
wherein the charge trapping portion further includes a third nitride film,
the third nitride film is formed directly on the second nitride film, and
the third nitride film is a nitride film in which a total concentration of the N—H bonds and Si—H bonds is 5×10 20 cm −3 or less.
4. The nonvolatile semiconductor memory device according to claim 3 ,
wherein the film thickness of the third nitride film is 3 nm or less.
5. The nonvolatile semiconductor memory device according to claim 1 , further comprising a second gate electrode formed over the region of the semiconductor substrate between the source and drain regions.
6. The nonvolatile semiconductor memory device according to claim 1 ,
wherein the first nitride film is formed by depositing a nitride film by a chemical vapor deposition method and then being nitrided by nitrogen in a plasma state.
7. The nonvolatile semiconductor memory device according to claim 1 ,
wherein the first nitride film is deposited and formed by a sputtering method.
8. The nonvolatile semiconductor memory device according to claim 1 ,
wherein the first nitride film is deposited and formed by an atomic layer deposition method in which SiCl 4 or Si 2 Cl 6 and a nitrogen gas in a plasma state are alternately exposed to the film.
9. The nonvolatile semiconductor memory device according to claim 1 ,
wherein an oxide film is further disposed between the first nitride film and the surface of the semiconductor substrate, and
the first nitride film is formed with a part of the oxide film being subjected to plasma nitridation.
10. The nonvolatile semiconductor memory device according to claim 1 ,
wherein the first nitride film is an oxynitride film.
11. The nonvolatile semiconductor memory device according to claim 1 ,
wherein the nitride film is a silicon nitride film, and when a composition of the silicon nitride film is Si 3+x N 4 , X is 0.05 or less.
12. The nonvolatile semiconductor memory device according to claim 1 , further comprising
an additional nitride film that covers an entirety of the surface of the semiconductor substrate in the memory region except for a contact part of the semiconductor substrate.
13. The nonvolatile semiconductor memory device according to claim 1 , further comprising an oxide film formed between the surface of the semiconductor substrate and the charge trapping portion,
wherein a bond between a halogen element and a silicon element is present in an interface between the oxide film and the semiconductor substrate or in the oxide film.
14. The nonvolatile semiconductor memory device according to claim 13 ,
wherein the halogen element is fluorine.