Backside cavity formation in semiconductor devices

• US 9,859,225 B2
• Filed: 05/13/2016
• Issued: 01/02/2018
• Est. Priority Date: 05/15/2015
• Status: Active Grant

• Current Assignee: Skyworks Solutions Incorporated
• Original Assignee: Skyworks Solutions Incorporated
• Inventors: Petzold, David T., Whitefield, David Scott
• Primary Examiner(s): Nguyen, Dao H
• Application Number:
  US15/154,817
• Publication Number:
  US 20160336228A1
• Time in Patent Office: 599 Days
• Field of Search: 257252, 257253, 257415, 257416, 257617, 257E21002, 257E21499, 257E21597, 257E23011, 257E29324, 257E29255, 438 48, 438 49, 438 52, 438106
• CPC Class Codes: H01L 21/30604 Chemical etching
• CPC Class Codes: H01L 21/6835 using temporarily an auxiliary support
• CPC Class Codes: H01L 21/7624 using semiconductor on insulator [SOI] technology H01L21/76297 takes precedence; manufacture of integrated circuits on insulating substrates H01L21/84; silicon on sapphire [SOS] technology H01L21/86
• CPC Class Codes: H01L 21/76251 using bonding techniques
• CPC Class Codes: H01L 21/764 Air gaps H01L21/76264 takes precedence
• CPC Class Codes: H01L 21/768 Applying interconnections to be used for carrying current between separate components within a device comprising conductors and dielectrics
• CPC Class Codes: H01L 21/76802 by forming openings in dielectrics
• CPC Class Codes: H01L 21/76877 Filling of holes, grooves or trenches, e.g. vias, with conductive material
• CPC Class Codes: H01L 21/76895 Local interconnects; Local pads, as exemplified by patent document EP0896365
• CPC Class Codes: H01L 21/76898 formed through a semiconductor substrate
• CPC Class Codes: H01L 21/84 the substrate being other than a semiconductor body, e.g. being an insulating body
• CPC Class Codes: H01L 2221/68318 Auxiliary support including means facilitating the separation of a device or wafer from the auxiliary support
• CPC Class Codes: H01L 2221/68327 used during dicing or grinding
• CPC Class Codes: H01L 2221/6834 used to protect an active side of a device or wafer
• CPC Class Codes: H01L 2221/68359 used as a support during manufacture of interconnect decals or build up layers
• CPC Class Codes: H01L 2221/68368 used in a transfer process involving at least two transfer steps, i.e. including an intermediate handle substrate
• CPC Class Codes: H01L 2223/6677 for antenna, e.g. antenna included within housing of semiconductor device antennas per se H01Q
• CPC Class Codes: H01L 2224/03 Manufacturing methods
• CPC Class Codes: H01L 2224/03002 for supporting the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/04042 Bonding areas specifically adapted for wire connectors, e.g. wirebond pads
• CPC Class Codes: H01L 2224/05554 : being square
• CPC Class Codes: H01L 2224/06135 : Covering only the peripheral area of the surface to be connected, i.e. peripheral arrangements
• CPC Class Codes: H01L 2224/45099 : Material
• CPC Class Codes: H01L 2224/48091 : Arched
• CPC Class Codes: H01L 2224/48227 : connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 : Layer and wire connectors
• CPC Class Codes: H01L 2224/94 : at wafer-level, i.e. with connecting carried out on a wafer comprising a plurality of undiced individual devices
• CPC Class Codes: H01L 23/3121 : a substrate forming part of the encapsulation
• CPC Class Codes: H01L 23/5283 : Cross-sectional geometry
• CPC Class Codes: H01L 23/535 : including internal interconnections, e.g. cross-under constructions internal lead connections H01L23/481
• CPC Class Codes: H01L 23/562 : Protection against mechanical damage H01L23/02, H01L23/28 take precedence
• CPC Class Codes: H01L 23/66 : High-frequency adaptations
• CPC Class Codes: H01L 24/05 : of an individual bonding area
• CPC Class Codes: H01L 24/06 : of a plurality of bonding areas
• CPC Class Codes: H01L 24/48 : of an individual wire connector
• CPC Class Codes: H01L 24/73 : Means for bonding being of different types provided for in two or more of groups H01L24/10, H01L24/18, H01L24/26, H01L24/34, H01L24/42, H01L24/50, H01L24/63, H01L24/71
• CPC Class Codes: H01L 25/16 : the devices being of types provided for in two or more different main groups of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. forming hybrid circuits
• CPC Class Codes: H01L 27/1203 : the substrate comprising an insulating body on a semiconductor body, e.g. SOI three-dimensional layout H01L27/0688
• CPC Class Codes: H01L 28/10 : Inductors
• CPC Class Codes: H01L 29/0649 : Dielectric regions, e.g. SiO2 regions, air gaps
• CPC Class Codes: H01L 29/66772 : Monocristalline silicon transistors on insulating substrates, e.g. quartz substrates H01L29/66666 takes precedence; thin film FinFETs H01L29/66795
• CPC Class Codes: H01L 29/78 : with field effect produced by an insulated gate H01L29/7725, H01L29/775, H01L29/778 take precedence
• CPC Class Codes: H01L 29/786 : Thin film transistors, i.e. transistors with a channel being at least partly a thin film transistors having only the source or the drain region on an insulator layer H01L29/0653; thin film FinFETs H01L29/785
• CPC Class Codes: H01L 29/78603 : characterised by the insulating substrate or support H01L29/78657 takes precedence
• CPC Class Codes: H01L 29/78648 : arranged on opposing sides of the channel
• CPC Class Codes: H01L 29/78654 : Monocrystalline silicon transistors
• 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 2924/00014 : the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/1306 : Field-effect transistor [FET]
• CPC Class Codes: H01L 2924/13091 : Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• CPC Class Codes: H01L 2924/1421 : RF devices
• CPC Class Codes: H01L 2924/15192 : Resurf arrangement of the internal vias
• CPC Class Codes: H01L 2924/15313 : being a land array, e.g. LGA
• CPC Class Codes: H03H 9/02566 : of semiconductor substrates
• CPC Class Codes: H03H 9/24 : Constructional features of resonators of material which is not piezoelectric, electrostrictive, or magnetostrictive
• CPC Class Codes: H04B 1/40 : Circuits
• CPC Class Codes: H04B 1/44 : Transmit/receive switching
• CPC Class Codes: H10N 39/00 : Integrated devices, or assemblies of multiple devices, comprising at least one piezoelectric, electrostrictive or magnetostrictive element covered by groups H10N30/00 – H10N35/00

Abstract

Fabrication of radio-frequency (RF) devices involves providing a field-effect transistor (FET) formed over an oxide layer formed on a semiconductor substrate, removing at least part of the semiconductor substrate to expose at least a portion of a backside of the oxide layer, applying an interface material to at least a portion of the backside of the oxide layer, removing at least a portion of the interface material to form a trench, and covering at least a portion of the interface material and the trench with a substrate layer to form a cavity.

Claims

1. A method for fabricating a radio-frequency device, the method comprising:

providing a field-effect transistor formed over an oxide layer formed on a semiconductor substrate;

removing at least part of the semiconductor substrate to expose at least a portion of a backside of the oxide layer;

applying an interface material to the exposed at least a portion of the backside of the oxide layer;

removing at least a portion of the interface material to form a trench; and

covering at least a portion of the interface material and the trench with a substrate layer to form a cavity.

2. The method of claim 1 further comprising applying a substrate contact layer to at least a portion of the backside of the oxide layer, the substrate contact layer being at least partially exposed in the cavity after said covering the at least a portion of the interface material and the trench.

3. The method of claim 2 wherein the substrate contact layer is electrically coupled to the field-effect transistor via a through-oxide via.

4. The method of claim 1 further comprising removing a handle wafer from a top-side of a passivation layer disposed above the field-effect transistor.

5. The method of claim 4 wherein the passivation layer is one of one or more dielectric layers formed over electrical connections to the field-effect transistor.

6. The method of claim 1 wherein the trench is at least partially below the field-effect transistor.

7. The method of claim 1 wherein the trench is at least partially below an electrical device coupled to the field-effect transistor via one or more electrical connections formed in one or more dielectric layers formed over the field-effect transistor.

8. The method of claim 1 wherein said removing the at least a portion of the interface material comprises etching away the at least a portion of the interface material.

9. A radio-frequency device comprising:

a field-effect transistor implemented over an oxide layer;

an interface layer applied to at least a portion of a backside of the oxide layer, the interface layer having a trench formed therein; and

a substrate layer covering at least a portion of the interface layer and the trench to form a cavity.

10. The radio-frequency device of claim 9 further comprising a substrate contact layer applied to at least a portion of the backside of the oxide layer, the substrate contact layer being at least partially exposed in the cavity.

11. The radio-frequency device of claim 10 wherein the substrate contact layer is electrically coupled to the field-effect transistor via a through-oxide via.

12. The radio-frequency device of claim 9 further comprising one or more dielectric layers formed over electrical connections to the field-effect transistor.

13. The radio-frequency device of claim 9 wherein the trench is at least partially below the field-effect transistor.

14. The radio-frequency device of claim 9 wherein the trench is at least partially below an electrical device coupled to the field-effect transistor via one or more electrical connections formed in one or more dielectric layers formed over the field-effect transistor.

15. A wireless device comprising:

a transceiver configured to process radio-frequency signals;

an radio-frequency module in communication with the transceiver, the radio-frequency module including a switching device having a field-effect transistor implemented over an oxide layer, an interface layer applied to at least a portion of a backside of the oxide layer, the interface layer having a trench formed therein, and a substrate layer covering at least a portion of the interface layer and the trench to form a cavity; and

an antenna in communication with the radio-frequency module, the antenna configured to facilitate transmitting and/or receiving of the radio-frequency signals.

16. The wireless device of claim 15 wherein the radio-frequency module includes a substrate contact layer applied to at least a portion of the backside of the oxide layer, the substrate contact layer being at least partially exposed in the cavity.

17. The wireless device of claim 16 wherein the substrate contact layer is electrically coupled to the field-effect transistor via a through-oxide via.

18. The wireless device of claim 15 wherein the switching device includes one or more dielectric layers formed over electrical connections to the field-effect transistor.

19. The wireless device of claim 15 wherein the trench is at least partially below the field-effect transistor.

20. The wireless device of claim 15 wherein the trench is at least partially below an electrical device coupled to the field-effect transistor via one or more electrical connections formed in one or more dielectric layers formed over the field-effect transistor.