Method of forming amorphous conducting diffusion barriers

• US 6,194,310 B1
• Filed: 06/01/2000
• Issued: 02/27/2001
• Est. Priority Date: 06/01/2000
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Laboratories of America Incorporated (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Hsu, Sheng Teng, Pan, Wei, Tweet, Douglas James, Evans, David Russell
• Primary Examiner(s): Niebling, John F.
• Assistant Examiner(s): GURLEY, LYNNE ANN
• Application Number:
  US09/585,680
• Time in Patent Office: 271 Days
• Field of Search: 438/643, 438/653, 438/680, 438/685
• US Class Current: 438/643
• CPC Class Codes: H01L 21/28556 by chemical means, e.g. CVD, LPCVD, PECVD, laser CVD H01L21/28518 - H01L21/28537 and H01L21/28568 take precedence
• CPC Class Codes: H01L 21/76864 Thermal treatment
• CPC Class Codes: H01L 2221/1078 Multiple stacked thin films not being formed in openings in dielectrics

Abstract

A method of forming conducting diffusion barriers is provided. The method produces substantially amorphous conducting diffusion barriers by depositing materials with varying ratios of elements throughout the diffusion barrier. Diffusion barriers of metal nitride, metal silicon nitride, are deposited using CVD, PECVD, or ALCVD, by depositing material with a first ratio of elements and then depositing substantially identical material with a different ratio of elements. The actual elements used are the same, but the ratio is changed. By changing the ratio of the elements within the same diffusion barrier, density variations are produced, and the material is not able to form undesirable polycrystalline structures.

Claims

1. A method of forming a conductive diffusion barrier comprising the steps of:

a) preparing a semiconductor substrate;

b) forming a barrier layer overlying the semiconductor substrate by using chemical vapor deposition (CVD) to deposit a refractory metal (M) nitride (N) having a first ratio of refractory metal to nitrogen M_aN_b, and then using CVD to deposit the same refractory metal nitride having a second ratio of refractory metal to nitrogen M_xN_y and

c) depositing a metal layer overlying the barrier layer.

2. The method as in claim 1, wherein step (b) is repeated a plurality of times.

3. The method as in claim 1, wherein the chemical vapor deposition (CVD) process is a plasma enhanced chemical vapor deposition (PECVD) process.

4. The method as in claim 1, wherein the chemical vapor deposition (CVD) process is an atomic layer chemical vapor deposition (ALCVD) process.

5. The method as in claim 1, wherein the refractory metal (M) is selected from the group consisting of Ti, Ta, and W.

6. The method as in claim 1, wherein the metal layer is a layer of metal selected from the group consisting of Al, Cu, Ag, and Au.

7. A method of forming a conductive diffusion barrier comprising the steps of:

a) preparing a semiconductor substrate;

b) forming a barrier layer overlying the semiconductor substrate by using chemical vapor deposition (CVD) to deposit a refractory metal (M) silicon (Si) nitride (N) having a first ratio of refractory metal to silicon to nitrogen M_aSi_bN_c, and then using CVD to deposit the same refractory metal silicon nitride having a second ratio of refractory metal to nitrogen M_xSi_yN_z, and

c) depositing a metal layer overlying the barrier layer.

8. The method as in claim 7, wherein the chemical vapor deposition (CVD) process is a plasma enhanced chemical vapor deposition (PECVD) process.

9. The method as in claim 7, wherein the chemical vapor deposition (CVD) process is an atomic layer chemical vapor deposition (ALCVD) process.

10. The method as in claim 7, wherein the refractory metal (M) is selected from the group consisting of Ti, Ta, and W.

11. The method as in claim 7, wherein the metal layer is a layer of metal selected from the group consisting of Al, Cu, Ag, and Au.

12. A method of forming a conductive diffusion barrier comprising the steps of:

a) preparing a semiconductor substrate;

b) placing the semiconductor substrate within a chemical vapor deposition (CVI) chamber;

c) introducing a TiN precursor and a nitrogen precursor into the chamber, wherein the nitrogen precursor is introduced at a first nitrogen precursor flow rate, whereby a TiN material is deposited having a first ratio of elements;

d) introducing a TiN precursor and a nitrogen precursor into the chamber, wherein the nitrogen precursor is introduced at a second nitrogen precursor flow rate, whereby a TiN material is deposited having a second ratio of elements;

e) annealing the material; and

f) depositing a layer of metal overlying the material.

13. The method of claim 12, wherein steps (c) and (d) are repeated as necessary to form a substantial amorphous conducting diffusion barrier of a desired thickness.

14. The method of claim 12, wherein the TiN precursor is Tetrakis(DiMethylAmino)Titanium (Ti(N(CH₃)₂)₄) (TDMAT), Tetrakis(DiEthylAmino)Titanium (Ti(N(C₂H₅)₂)₄) (TDEAT), or Tetrakis(Ethyl Methyl Amino)Titanium (TEMAT).

15. The method of claim 12, wherein the nitrogen precursor is ammonia (NH₃), dimethyl amine (N(CH₃)₂), or diethyl amine (N(C₂H₅)₂).

16. The method of claim 15, wherein the nitrogen precursor is introduced into the CVD chamber at a rate of between 0 and 50 sccm.