Semiconductor memory device and manufacturing method thereof
View Patent ↗After an ONO film in which a silicon nitride film ( 22 ) formed by a plasma nitriding method using a plasma processor having a radial line slot antenna is sandwiched by silicon oxide films ( 21 ), ( 23 ), a bit line diffusion layer ( 17 ) is formed in a memory cell array region ( 11 ) by an ion implantation as a resist pattern ( 16 ) taken as a mask, then lattice defects are given to the silicon nitride film ( 22 ) by a further ion implantation. Accordingly, a highly reliable semiconductor memory device can be realized, in which a high quality nitride film is formed in a low temperature condition, in addition, the nitride film can be used as a charge trap film having a charge capture function sufficiently adaptable for a miniaturization and a high integration which are recent demands.
1. A manufacturing method of a semiconductor memory device, comprising the steps of:
forming an insulating film including a nitride film formed on a semiconductor substrate by nothing but a plasma nitriding method or by a series of processes including the plasma nitriding method;
forming a pair of impurity diffusion layers with an impurity introduced into a surface layer of the semiconductor substrate;
forming charge trap centers with lattice defects given to portions corresponding to at least on the impurity diffusion layers of the nitride film before or after the formation of the impurity diffusion layer; and
forming a gate electrode so as to cross the impurity diffusion layer through the insulating film.
2. The manufacturing method of the semiconductor memory device according to claim 1 ,
wherein the lattice defects are selectively given to nothing but portions corresponding to on the impurity diffusion layers of the nitride film when the charge trap centers are formed.
3. The manufacturing method of the semiconductor memory device according to claim 1 ,
wherein the lattice defects are given to the whole surface of the nitride film when the charge trap centers are formed.
4. The manufacturing method of the semiconductor memory device according to claim 1 ,
wherein the lattice defects are given by performing a radio frequency processing using an inert gas to the nitride film.
5. The manufacturing method of the semiconductor memory device according to claim 1 ,
wherein the nitride film is formed by performing a nitriding processing with the plasma excited by a microwave in an atmosphere of a source gas including nitrogen atoms for generating a nitride radical.
6. The manufacturing method of the semiconductor memory device according to claim 5 ,
wherein the source gas is one kind selected from a NH 3 gas, a mixed gas of N 2 and H 2 , and N 2 gas, or a mixed gas of the NH 3 gas and N 2 gas, or a mixed gas of the NH 3 gas, the N 2 , and the H 2 .
7. The manufacturing method of the semiconductor memory device according to claim 1 ,
wherein the insulating film is a stacked film in which the nitride film is formed on an oxide film.
8. The manufacturing method of the semiconductor memory device according to claim 7 ,
wherein the oxide film under the nitride film is formed by one kind or combined plural kinds of methods selected from a thermal oxidation method, a plasma oxidation method and a thermal CVD oxidation method.
9. The manufacturing method of the semiconductor memory device according to claim 1 ,
wherein the insulating film is a stacked film in which the nitride film is sandwiched between respective upper and lower oxide films.
10. The manufacturing method of the semiconductor memory device according to claim 9 ,
wherein the oxide film under the nitride film is formed by one kind or combined plural kinds of methods selected from a thermal oxidation method, a plasma oxidation method and a thermal CVD oxidation method.
11. The manufacturing method of the semiconductor memory device according to claim 1 ,
wherein the insulating film is of a single layer structure constituted by nothing but the nitride film.
12. The manufacturing method of the semiconductor memory device according to claim 11 ,
wherein the oxide film under the nitride film is formed by one kind or combined plural kinds of methods selected from a thermal oxidation method, a plasma oxidation method and a thermal CVD oxidation method.
13. The manufacturing method of the semiconductor memory device according to claim 1 ,
wherein the lattice defects are given by introducing the impurity into the nitride film.
14. The manufacturing method of the semiconductor memory device according to claim 13 ,
wherein the lattice defects are given by introducing the impurity into the nitride film from a direction inclined with respect to a resist mask used once again, which is used also for the formation of the impurity diffusion layer, after the inpurity diffusion layer is formed.
15. The manufacturing method of the semiconductor memory device according to claim 13 ,
wherein the lattice defects are given by introducing the impurity into the nitride film by using a resist mask used for the formation of the impurity diffusion layer, to which a trimming is performed and of which openings are enlarged, after the impurity diffusion layer is formed.
16. The manufacturing method of the semiconductor memory device according to claim 13 ,
wherein the whole or a part of the insulating film including the nitride film is formed after the impurity diffusion layer is formed.
17. The manufacturing method of the semiconductor memory device according to claim 13 ,
wherein the impurity/impurities introduced into the nitride film is/are one kind or combined some kinds selected among silicon, oxygen, nitrogen, argon, fluorosis, boron, phosphorus, arsenic, indium, germanium and antimony.