Method for manufacturing an intergrated pressure sensor

• US 8,815,623 B2
• Filed: 08/05/2009
• Issued: 08/26/2014
• Est. Priority Date: 08/28/2008
• Status: Active Grant

• Current Assignee: Sensirion AG (Sensirion Holding AG)
• Original Assignee: Sensirion AG (Sensirion Holding AG)
• Inventors: Mayer, Felix, Bhler, Johannes, Streiff, Matthias, Hummel, Ren, Sunier, Robert
• Primary Examiner(s): NIKMANESH, SEAHVOSH J
• Application Number:
  US12/462,582
• Publication Number:
  US 20100055821A1
• Time in Patent Office: 1,847 Days
• Field of Search: None
• 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 pressure sensor, the pressure sensor comprising a semiconductor chip having a substrate, wherein the substrate has a first side and a second side opposite the first side,

the step of providing a pressure sensor further comprising the steps of

providing, on the first side of the substrate, a flexible membrane layer spanning a cavity, and

forming, by means of a laser, an opening extending from the second side of said substrate through said substrate, wherein the opening is connected to a side of said membrane.

2. The method of claim 1 wherein said bore is laterally displaced with respect to said cavity, and further comprising the step of forming a laterally extending channel, said channel connecting said cavity to said bore.

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

4. The method of claim 2 wherein said lid is affixed to a dielectric layer disposed on the first side of said substrate.

5. The method of claim 2 wherein the lid comprises a polymer layer.

6. The method of claim 2 wherein said lid is formed by a photoresist layer.

7. The method of claim 5, further comprising the step of applying said polymer layer as an epoxy dry film on said first side.

8. The method claim 3 wherein said membrane layer comprises a silicon layer, wherein said bore extends at least to said silicon layer.

9. The method of claim 8 wherein said silicon layer forms 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 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 further comprising

providing a plurality of said pressure sensors simultaneously on the substrate,

forming a lid simultaneously on all said sensors, and

cutting said substrate, after forming said lid, into individual sensors.

13. The method of claim 12, wherein the step of forming the lid further comprises the steps of

providing a lid wafer having a plurality of openings and

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

14. The method of claim 2 further 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 such that it is covered by said membrane, and

forming a second section of said channel between said dielectric layers and said lid, and

applying an additional spacer layer between said dielectric layers and said lid.

17. The method Of claim 1 wherein the step of forming the opening by means of a laser comprises drilling said bore 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 pressure sensor including a substrate, the substrate comprising a semiconductor, and wherein said substrate comprises a cavity and a flexible membrane formed on a first side of said substrate, wherein said membrane extends over said cavity, step of providing a pressure sensor further comprising the steps of

forming an opening extending from a second side of said substrate through said substrate, wherein said opening is connected to a 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 with respect to said cavity, and wherein a channel is formed, said channel connecting said cavity and said bore, and

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 polymer layer is a photoresist layer.

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

providing a pressure sensor comprising a substrate, the substrate comprising semiconducting material, wherein said substrate comprises a cavity and a flexible membrane layer integrated on a first side of said substrate, wherein said membrane layer extends over said cavity, the step of providing a pressure sensor further comprising the steps of

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 an opening extending from a second side of said substrate through said substrate, said opening connecting 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 with 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, and

further comprising the steps of

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

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