Method of depositing a higher permittivity dielectric film
A method of depositing a high permittivity dielectric film on a doped silicon or silicon compound layer of a wafer. The method includes a first step of nitriding a specific element (A) such as hafnium Hf to form a nitride film (A x N y ) on the silicon layer, wherein the specific element (A) and nitrogen (N) in the nitride film (A x N y ) have a predetermined fraction relationship between x and y; a second step of oxidizing the nitride film in a oxygen atmosphere to form the dielectric film (AON).
1. A method of depositing a high permittivity dielectric film, the method comprises:
forming an SiO 2 layer over a silicon substrate by heat treatment;
nitriding a specific metal element (A) to form a nitride film (A x N y ) on the SiO 2 layer, wherein said specific metal element (A) and nitrogen (N) in said nitride film (A x N y ) have a predetermined fraction relationship between x and y, wherein a reactive sputtering method is used for the nitride film deposition such that metal (A) atoms from a metal target are sputtered in a nitrogen atmosphere; and
annealing said nitride film in an oxygen atmosphere to form said dielectric film (AON) which is oxidized and nitrided, wherein the annealing is at a temperature of 400-1000° C., such that the oxidizing and annealing occur at the same time, wherein the entire annealing process is carried out in an oxygen atmosphere,
wherein said specific metal element (A) and nitrogen (N) in said nitride film (A x N y ) have a relationship that y is smaller than its stoichiometric value throughout the entire nitride film,
wherein the high permittivity dielectric film is a gate dielectric layer.
2. The method of depositing a high permittivity dielectric film according to claim 1 , wherein said specific metal element (A) is any one which belongs to the third, fourth, or fifth family of the periodic table of the elements.
3. The method of depositing a high permittivity dielectric film according to claim 2 , wherein said specific metal element (A) is hafnium (Hf).
4. The method of depositing a high permittivity dielectric film according to claim 3 , wherein said hafnium (Hf) and nitrogen (N) in said nitride film (Hf x N y ) have a relationship that 0<y<1 for x=1.
5. The method of depositing a high permittivity dielectric film according to claim 1 , wherein the annealing process is carried out at a temperature of 600 to 1000° C.
6. The method of depositing a high permittivity dielectric film according to claim 1 , wherein the SiO 2 layer is formed by a chemical vapor deposition (CVD) or rapid thermal processing (RTP) process.
7. The method of depositing a high permittivity dielectric film according to claim 1 , further comprising a step of removing native silicon oxide of the silicon substrate by HF solution before forming the SiO 2 layer over the silicon substrate.
8. The method of depositing a high permittivity dielectric film according to claim 1 , wherein the reactive sputtering method is carried out under condition that the metal target is disposed to be non-parallel to the silicon substrate, and a nitrogen gas and inert gas are introduced at pressure of 0.5 Pa and lower in a state of rotating the substrate.
9. The method of depositing a high permittivity dielectric film according to claim 1 , wherein the high permittivity dielectric film has an equivalent oxide thickness of less than 1 nm.
10. The method of depositing a high permittivity dielectric film according to claim 1 , wherein the high permittivity dielectric film has a leakage current less than 10 −1 A/cm 2 .
11. The method of depositing a high permittivity dielectric film according to claim 10 , wherein the high permittivity dielectric film has an equivalent oxide thickness of less than 1 nm.