Method and structure for adhering MSQ material to liner oxide

• US 6,303,525 B1
• Filed: 08/18/2000
• Issued: 10/16/2001
• Est. Priority Date: 08/18/2000
• Status: Expired due to Fees

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: Philips Electronics North America Corporation (Koninklijke Philips N.V.)
• Inventors: Annapragada, Rao Venkateswara
• Primary Examiner(s): DANG, TRUNG Q
• Application Number:
  US09/642,074
• Time in Patent Office: 424 Days
• Field of Search: 438/778, 438/780, 438/782, 438/781, 438/787
• US Class Current: 438/782
• CPC Class Codes: H01L 21/02134 the material comprising hydrogen silsesquioxane, e.g. HSQ
• CPC Class Codes: H01L 21/02137 the material comprising alkyl silsesquioxane, e.g. MSQ
• CPC Class Codes: H01L 21/02282 liquid deposition, e.g. spin-coating, sol-gel techniques, spray coating
• CPC Class Codes: H01L 21/02304 formation of intermediate layers, e.g. buffer layers, layers to improve adhesion, lattice match or diffusion barriers
• CPC Class Codes: H01L 21/02362 formation of intermediate layers, e.g. capping layers or diffusion barriers
• CPC Class Codes: H01L 21/3124 layers comprising hydrogen silsesquioxane
• CPC Class Codes: H01L 21/76801 characterised by the formation and the after-treatment of the dielectrics, e.g. smoothing
• CPC Class Codes: H01L 21/76834 formation of thin insulating films on the sidewalls or on top of conductors H01L21/76831 takes precedence

Abstract

A method for depositing a liner dielectric on a semiconductor substrate provides for sufficient adhesion of low dielectric constant spin-on materials among metal layers in sub-micron processes. In an example embodiment, a method for adhering MSQ provides for a liner oxide on an aluminum alloy layer on a semiconductor substrate. First, the substrate is placed into a PECVD environment. A gas mixture of trimethylsilane and N₂O is introduced into the PECVD environment at a trimethylsilane-to-N₂O ratio of about 1:20 to 1:30. The gas mixture is reacted to deposit an oxide liner of a predetermined thickness. Adjusting the gas mixture trimethylsilane-to-N₂O ratio to about 1:3 to 1:7 over the course of about 5 to 20 seconds, and sustaining the reaction thereof, deposits a methyl doped oxide.

Claims

1. On a semiconductor substrate, a method of adhering a spin-on dielectric on a metal layer comprising:

depositing a first predetermined thickness of a liner dielectric on the metal layer, the liner dielectric having a chemical affinity to the metal layer;

forming a transition layer of a second predetermined thickness on the liner dielectric, the transition layer having less chemical affinity to the metal layer and increasing chemical affinity to the spin-on dielectric as the thickness of the transition layer increases; and

depositing a third predetermined thickness of liner dielectric on the transition layer, the liner dielectric having a chemical affinity to the spin-on dielectric.

2. The method of claim 1 wherein the spin-on dielectric includes at least one of the following:

methyl silsesquioxane, hydrogen silsesquioxane.

3. The method of claim 2 wherein the first predetermined thickness of liner dielectric includes silicon dioxide, silicon-rich oxide, and Si_xO_y.

4. The method of claim 3 wherein the transition layer comprises a region of silicon dioxide transitioning to a region of methyl doped oxide.

5. The method of claim 1 wherein,

the liner dielectric is deposited by one of the following: chemical vapor deposition (CVD) and plasma-enhanced chemical vapor deposition (PECVD); and

wherein,

the transition layer is formed by one of the following;

chemical vapor deposition (CVD) and plasma-enhanced chemical vapor deposition (PECVD).

6. The method of claim 5 wherein the transition layer comprises a methyl doped oxide film formed in a PECVD environment using precursor gases selected from at least one of the following:

trimethylsilane, tetramethylsilane.

7. The method of claim 6 wherein the precursor gas is blended with nitrogen oxide (N₂O) in a predetermined ratio to yield silicon dioxide transitioning to methyl doped oxide.

8. The method of claim 7 wherein the transition layer is deposited with a thickness in the range of about 100 Å

to 2000 Å

; and

wherein,

the SiO₂ thickness is in the range of about 50 Å

to about 100 Å

; and

wherein

the methyl doped oxide thickness is in the range of about 50 Å

to about 1000 Å

.

9. A method for adhering a silsesquioxane compound, providing a liner dielectric on an aluminum alloy metal layer on a semiconductor substrate, the method comprising:

placing the substrate in a CVD environment;

introducing a gas mixture into the CVD environment, wherein the gas mixture comprises a precursor gas and N₂O at a defined precursor gas-to-N₂O ratio; and

reacting the gas mixture to deposit the liner dielectric of a predetermined thickness.

10. The method of claim 9 wherein reacting the gas mixture comprises,

adjusting the precursor gas-to-N₂O ratio so that silicon dioxide is deposited on the aluminum alloy metal layer at a first predetermined thickness; and

re-adjusting the precursor gas-to-N₂O ratio so that methyl doped oxide is deposited on the silicon dioxide at a second predetermined thickness.

11. The method of claim 10 wherein the re-adjusting the precursor gas-to-N₂O ratio transitions the liner dielectric from a region of silicon dioxide to a region of methyl doped oxide.

12. The method of claim 9 wherein the precursor gas includes at least one of the following:

trimethylsilane, tetramethylsilane.

13. A method for adhering a silsesquioxane compound providing a liner oxide on an aluminum alloy metal layer on a semiconductor substrate, the method comprising:

placing the substrate in a PECVD environment;

introducing a gas mixture into the PECVD environment, wherein the gas mixture comprises a precursor gas and N₂O at a precursor gas-to-N₂O first ratio of about 1;

20 to 1;

30;

reacting the gas mixture to deposit an oxide liner of a thickness in the range of about 100 Å

to 1000 Å

; and

adjusting the gas mixture and sustaining the reaction thereof of the precursor gas and N₂O at a precursor gas-to-N₂O second ratio of about 1;

3 to about 1;

7 to deposit a methyl doped oxide liner of a thickness in the range of about 100 Å

to 1000 Å

.

14. The method of claim 13 wherein the adjusting of the gas mixture from the first precursor gas-to-N₂O ratio to the second precursor gas-to-N₂O ratio takes about 3 to 30 seconds.

15. The method of claim 13 wherein the precursor gas includes at least one of the following:

trimethylsilane, tetramethylsilane.