Method for manufacturing an intergrated pressure sensor

• US 20100055821A1
• Filed: 08/05/2009
• Published: 03/04/2010
• Est. Priority Date: 08/28/2008
• Status: Active Grant

• Current Assignee: Sensirion AG (Sensirion Holding AG)
• Original Assignee: Sensirion AG (Sensirion Holding AG)
• Inventors: Hummel, René, Streiff, Matthias, Bühler, Johannes, Mayer, Felix, Sunier, Robert
• Granted Patent: US 8,815,623 B2
• Time in Patent Office: Days
• US Class Current: 438/51
• CPC Class Codes: B81B 2201/0264 Pressure sensors
• CPC Class Codes: B81B 2203/0127 Diaphragms, i.e. structures separating two media that can control the passage from one medium to another; Membranes, i.e. diaphragms with filtering function
• CPC Class Codes: B81B 2203/0315 Cavities
• CPC Class Codes: B81B 2203/0353 Holes
• CPC Class Codes: B81C 1/00087 Holes
• CPC Class Codes: B81C 1/00801 Avoid alteration of functional structures by etching, e.g. using a passivation layer or an etch stop layer B81C1/00595, B81C1/00468 take precedence
• CPC Class Codes: B81C 2201/0143 Focussed beam, i.e. laser, ion or e-beam
• CPC Class Codes: G01L 9/0073 using a semiconductive diaphragm
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• 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

Abstract

A differential pressure sensor comprises a membrane arranged over a cavity on a semiconductor substrate. A lid layer is arranged at the top side of the device and comprises an access opening for providing access to the top side of the membrane. A channel extends laterally from the cavity and intersects with a bore. The bore is formed by laser drilling from the bottom side of the substrate and provides access to the bottom side of the membrane. The bore extends all through the substrate and optionally into the lid layer.

Claims

1. A method for manufacturing a pressure sensor comprising the steps of

providing a semiconductor substrate, wherein said substrate comprises a flexible membrane integrated on a first side of said substrate, and

forming a opening extending from a second side of said substrate through said substrate and being connected to one side of said membrane, wherein said second side is opposite to said first side,

wherein said opening is formed by drilling a bore through said substrate by means of a laser.

2. The method of claim 1 wherein said membrane extends over a cavity, wherein said bore is laterally displaced in respect to said cavity and wherein a channel is formed for connecting said cavity and said bore.

3. The method of claim 2 further comprising the step of forming a lid on said first side and wherein said bore ends at said lid.

4. The method of claim 2 wherein said lid is applied from said first side to said substrate.

5. The method of claim 2 wherein the step of forming said lid comprises forming a polymer layer on said first side.

6. The method of claim 5 wherein said lid is formed by a photoresist layer.

7. The method of claim 6 wherein said polymer layer is applied as a solid film to said first side, and in particular wherein said layer is applied as an epoxy dry film.

8. The method claim 3 wherein said lid comprises a silicon layer, wherein said bore is drilled to reach at least to said silicon layer.

9. The method of claim 8 wherein said silicon layer forms said membrane and/or at least part of a wall of said channel.

10. The method of claim 2 wherein said lid is formed prior to drilling said bore, and in particular wherein said bore extends through part of said lid.

11. The method of claim 2 wherein said lid is formed after drilling said bore.

12. The method of claim 2 comprising the steps of

manufacturing a plurality of said pressure sensors simultaneously on a semiconductor wafer,

forming said lid simultaneously on all said sensors, and

cutting said wafer, after forming said lid, for forming individual sensors.

13. The method of claim 12 further comprising the steps of

providing a lid wafer having a plurality of openings and

applying said lid wafer to the first side of said semiconductor wafer with said openings being aligned with said membranes.

14. The method of claim 2 comprising the steps of applying one or more dielectric layers to said first side of said substrate and forming at least part of said channel as a recess in said dielectric layers.

15. The method claim 14 wherein said lid forms at least part of a wall of said channel.

16. The method claim 15 comprising the steps of

forming a first section of said channel in said recess and covering it by a layer that forms said membrane, and

forming a second section of said channel between said dielectric layers and said lid, wherein an additional spacer layer is applied between said dielectric layers and said lid.

17. The method of claim 1 wherein said bore is drilled from said second side through said substrate.

18. The method of claim 1 comprising the steps of

drilling said bore by means of laser pulses,

counting said laser pulses, and

ending the drilling of said bore after a predefined number of laser pulses.

19. A method for manufacturing a pressure sensor comprising the steps of

providing a semiconductor substrate, wherein said substrate comprises a cavity and a flexible membrane integrated on a first side of said substrate, wherein said membrane extends over said cavity, and

forming a opening extending from a second side of said substrate through said substrate and being connected to one side of said membrane, wherein said second side is opposite to said first side, wherein said opening is formed by drilling a bore through said substrate by means of a laser, wherein said bore is laterally displaced in respect to said cavity, and wherein a channel is formed for connecting said cavity and said bore,

forming a lid on said first side by applying a polymer layer on said first side, wherein said bore ends at said lid.

20. The method of claim 19 wherein said lid is formed by a photoresist layer.

21. A method for manufacturing a pressure sensor comprising the steps of

providing a semiconductor substrate, wherein said substrate comprises a cavity and a flexible membrane integrated on a first side of said substrate, wherein said membrane extends over said cavity, and

applying one or more dielectric layers to said first side of said substrate and forming at least part of a channel as a recess in said dielectric layers

forming a opening extending from a second side of said substrate through said substrate and being connected to one side of said membrane, wherein said second side is opposite to said first side, wherein said opening is formed by drilling a bore through said substrate by means of a laser, wherein said bore is laterally displaced in respect to said cavity, and wherein said channel connects said cavity and said bore,

forming a lid on said first side by applying a polymer layer on said first side, wherein said bore ends at said lid and wherein said lid forms at least part of a wall of said channel,

said method further comprising the steps of

forming a first section of said channel in said recess and covering it by a layer that forms said membrane, and

forming a second section of said channel between said dielectric layers and said lid, wherein an additional spacer layer is applied between said dielectric layers and said lid.