Structure of merged vertical capacitor inside spiral conductor for RF and mixed-signal applications

• US 6,486,529 B2
• Filed: 02/04/2002
• Issued: 11/26/2002
• Est. Priority Date: 03/05/2001
• Status: Expired due to Term

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Chi, Min-Hwa, Tu, Yeur-Luen, Tsai, Chia-Shiung
• Primary Examiner(s): TSAI, H JEY
• Application Number:
  US10/066,512
• Publication Number:
  US 20020123159A1
• Time in Patent Office: 295 Days
• Field of Search: 438/238-240, 438/253-256, 438/381, 438/396-399, 257/303-311, 257/531-533
• US Class Current: 257/531
• CPC Class Codes: H01L 23/5223 Capacitor integral with wiring layers
• CPC Class Codes: H01L 23/5227 Inductive arrangements or effects of, or between, wiring layers other inductive arrangements H01L23/645
• CPC Class Codes: H01L 27/08 including only semiconductor components of a single kind
• CPC Class Codes: H01L 28/10 Inductors
• CPC Class Codes: H01L 28/91 made by depositing layers, e.g. by depositing alternating conductive and insulating layers
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 2924/3011 Impedance

Abstract

A new method and structure is provided for the simultaneous creation of inductive and capacitive components in a monolithic substrate. The invention provides a method and structure whereby a vertical spiral inductor is created on the surface of a substrate. Multiple capacitors are created inside the coils of the vertical spiral conductor. A base layer of dielectric is deposited over the surface of a semiconductor substrate, contact plugs are provided in the base layer of dielectric. Multiple layers of dielectric are deposited over the surface of the base layer, layers of coils are created in the multiple layers of dielectric. Vias are provided in the layer of dielectric to interconnect overlying coils of the spiral inductor. An etch stop layer is deposited on the surface of the upper layer of dielectric. At least two openings are etched in the multiple layers of dielectric, these at least two openings are surrounded by the coils of the spiral inductor and align with the contact plugs provided in the base layers. Spacers are formed on the sidewalls of the openings, the bottom electrode layer, dielectric layer and top electrode layer of the at least two capacitors are deposited over the spacers. The openings are filled with a conductive material, the surface of the conductive material is polished down to the surface of the etch stop.

Claims

1. A structure of at least two vertical capacitors inside a spiral inductor for high-frequency and mixed digital and analog applications, comprising:

a semiconductor substrate, said substrate having been provided with at least one MOS device on the surface thereof, at least two contact junctions having been provided in the surface of said substrate, said at least two contact junctions being contact junctions to which bottom electrodes of at least two vertical capacitors to be created on the surface of said substrate are being connected, a base layer of dielectric having been deposited over the surface of said substrate, including the surface of said at least two contact junctions, at least two conductive contact plugs having been formed through said base layer of dielectric contacting said at least two contact junctions provided in said surface of said substrate, said at least two contact plugs forming contacts for a bottom electrode of overlying at least two capacitors, the surface of said base layer of dielectric having been polished;

a first etch stop layer deposited over the surface of said base layer of dielectric;

a first layer of conductive material deposited over the surface of said first etch stop layer;

a first pattern of interconnect lines formed on the surface of said first etch stop layer, said first pattern of interconnect lines comprising a first layer of coils of said spiral inductor;

a first layer of dielectric deposited over the surface of said base layer of dielectric, including the surface of said first pattern of interconnect lines;

a first via created in said first layer of dielectric, said first via being aligned with and contacting said first layer of interconnect lines;

a second pattern of interconnect lines created on the surface of said first layer of dielectric, said second pattern of interconnect lines comprising a second layer of coils of said spiral inductor;

a second layer of dielectric deposited over the surface of said first layer of dielectric, including the surface of said second pattern of interconnect lines;

a second via created in said second layer of dielectric, said second via providing an electrical connection between said second pattern of interconnect lines and an adjacent, overlying pattern of interconnect lines;

a third pattern of interconnect lines created on the surface of said second layer of dielectric, said third pattern of interconnect lines comprising a third layer of coils of said spiral inductor;

a third layer of dielectric deposited over the surface of said second layer of dielectric, including the surface of said third pattern of interconnect lines, said third layer of interconnect lines making electrical contact with said second via created in said second layer of dielectric, said third layer of dielectric being an upper layer of dielectric;

a second etch stop layer deposited over the surface of said third layer of dielectric;

at least two openings created in said second etch stop layer, said at least two openings being aligned with said at least two conductive contact plugs provided in said base layer of dielectric;

at least two openings having sidewalls further having bottom surfaces created in said third, second, first layer of dielectric and said first etch stop layer, said at least two openings being surrounded by coils comprising said first, second and third layer of coils of said spiral conductor, said etching partially exposing inner coils of said first, second and third layer of coils of said spiral conductor, continuing said etching to the point of exposing the surface of said at least two conductive contact plugs created in said base layer of dielectric;

double layered spacers′

created on the sidewalls of said openings created in said first, second, third layer of dielectric and said first etch stop layer;

a layer of Ti/TiN or Ti/TaN conformally deposited over the surface of said double layered spacers on the sidewalls of said at least two openings created in said first, second, third layer of dielectric and said first etch stop layer and over said bottom surfaces of said at least two openings, including the surface of said second etch stop layer, said layer of Ti/TiN or Ti/TaN having been removed from the surface of said second etch stop layer, exposing the surface of said second etch stop layer, further said layer of Ti/TiN or Ti/TaN having been removed from the surface of said double layered spacers around upper perimeters of said at least two openings created in said first, second, third layer of dielectric and said first etch stop layer, partially exposing said double layered spacers, said layer of Ti/TiN or Ti/TaN partially left in place overlying said double layered spacers, said layer of Ti/TiN or Ti/TaN in place overlying said bottom surface of said at least two openings;

a layer of Ta₂O₅ deposited over the surface of said second etch stop layer, including said layer of Ti/TiN or Ti/TaN in place overlying said double layered spacers, including the surface of said partially exposed double layered spacers, including said bottom surface of said at least two openings;

a layer of TiN/Ti or TaN/Ti conformally deposited over the surface of said layer of Ta₂O₅;

a first layer of conductive material deposited over the surface of said layer of TiN/Ti or TaN/Ti, filling said at least two openings with said first layer of conductive material, said first layer of conductive material having been removed from above the surface of said second etch stop layer, leaving in place a layer of said first layer of metal having a surface and filling said at least two openings;

a second layer of conductive material, deposited over the surface of said second etch stop layer and the surface of said first layer of metal filling said at least two openings, said second layer of conductive material having been patterned and etched, creating at least two contact points to said at least two vertical capacitors, said at least two contact points overlying said at least two openings created in said first, second, third layer of dielectric and said first etch stop layer, said second layer of conductive material having been removed from the surface of said second etch stop layer.

2. The structure of claim 1, said layers of coils of said spiral inductor being limited to one layer of coils by eliminating said first layer of dielectric up through and including said second via created in said second layer of dielectric.

3. The structure of claim 1, said layers of coils of said spiral inductor being limited to two layers of coils by eliminating said first layer of dielectric up through and including said first via in created in said first layer of dielectric.

4. The structure of claim 1, said layers of coils of said spiral inductor being extended to multiple layers of coils, said extension having been implemented by repetitive cycles of depositing a layer of conductive material, patterning and etching said layer of conductive material, depositing a layer of dielectric followed by creating a via in said layer of dielectric, said multiple layers of coils being formed prior to said depositing said upper layer of dielectric.

5. The structure of claim 1, said at least two conductive contact plugs having been formed through said base layer of dielectric comprising tungsten.

6. The structure of claim 1, said double layered spacers on the sidewalls of said openings created in said first, second and third layer of dielectric comprising a first layer of oxide to a thickness of about 500 Angstrom over inside surfaces of said at least two openings created in said first, second, third layer of dielectric and said first etch stop layer over which has been deposited second layer of oxide to a thickness of about 700 Angstrom.

7. The structure of claim 1, said conformally deposited layer of Ti/TiN or T/TaN over the surface of said double layered spacers on the sidewalls of said at least two openings comprising a layer of Ti/TiN or T/TaN deposited to a thickness between about 10 and 100 Angstrom.

8. The structure of claim 1, said deposited layer of Ta₂O₅ comprising a layer of Ta₂O₅ deposited to a thickness between about 200 and 500 Angstrom.

9. The structure of claim 1, said conformally deposited layer of TiN/Ti or TaN/Ti over the surface of said layer of Ta₂O₅ comprising a layer of TiN/Ti or TaN/Ti deposited to a thickness between about 10 and 100 Angstrom.

10. The structure of claim 1, said first etch stop layer comprising silicon nitride, deposited preferably to a thickness between about 150 and 250 Angstrom and more preferably to a thickness of about 100 Angstrom.

11. The structure of claim 1, said upper layer of said multiple layers of dielectric having a thickness of between about 1500 and 2500 Angstrom.

12. The structure of claim 1, said first, second and third layers of dielectric comprising Inter Metal Dielectric oxide.

13. The structure of claim 1 wherein said layer of Ti/TiN or Ti/TaN is preferably deposited by depositing said Ti and said TiN or TaN and using CVD methods at low temperature of less than about 450 degrees C. whereby both depositions are preferably performed using separate chambers of one equipment platform.

14. The structure of claim 1 wherein said layer of metal for each layer of said inductor comprises a low resistivity metal, thereby providing low resistivity losses due to resistance of said coils.

15. The structure of claim 1 wherein said first, second and third pattern of interconnect lines and said first, second vias comprise a low resistivity metal, thereby providing low resistivity losses due to resistance of said coils.

17. The structure of claim 1 wherein said base layer of dielectric has a thickness that exceeds a thickness of said first, second and third layer of dielectric by a measurable amount.

18. The structure of claim 1, said contact points having been provided in the surface of said substrate comprising n⁺ doped points of electrical contact in the surface of said substrate, said contact points being connected to separate circuits, said contact points being at different voltage levels.

19. The structure of claim 1 wherein said contact points having been provided in the surface of said substrate are selected from a group of contact point consisting of doped points of electrical contact being shorted to said substrate being at a common voltage level and individually doped contact points of either n⁺ or p⁺ type doping.

20. The structure of claim 1, said at least two contact junctions having been provided in the surface of said substrate comprising n⁺ doped points of electrical contact in the surface of said substrate, said contact points being connected to separate circuits, said contact points being at different voltage levels.

21. The structure of claim 1, said at least two contact junctions having been provided in the surface of said substrate comprising n⁺ doped points of electrical contact in the surface of said substrate, said contact points being connected to separate circuits, said contact points being at different voltage levels.

22. The structure of claim 1, said at least two contact junctions having been provided in the surface of said substrate being selected from a group of contact point consisting of doped points of electrical contact being shorted to said substrate being at a common voltage level and individually doped contact points of either n⁺ or p⁺ type doping.

16. The structure of 1 claim wherein said first layer of dielectric has a thickness exceeding a thickness of each of said multiple layers of dielectric by a measurable amount.