Bonding process and bonded structures

• US 8,729,685 B2
• Filed: 04/30/2010
• Issued: 05/20/2014
• Est. Priority Date: 04/30/2009
• Status: Active Grant

• Current Assignee: Silex Microsystems AB (Sai Microelectronics, Inc.)
• Original Assignee: Silex Microsystems AB (Sai Microelectronics, Inc.)
• Inventors: Ebefors, Thorbjrn, Svedin, Niklas, Eriksson, Anders, Klvesten, Edward
• Primary Examiner(s): Nguyen, Dao H
• Assistant Examiner(s): Nguyen, Tram H
• Application Number:
  US13/318,205
• Publication Number:
  US 20120076715A1
• Time in Patent Office: 1,481 Days
• Field of Search: 257/684, 257687-733, 257787-796, 257E23001-E23194, 257E21499-E21519, 257/685, 257/686, 257E25031-E25032, 257/E23.04, 257E21502-E21504, 438/15, 438/25, 438/26, 438/51, 438/55, 438/112, 438/124, 438/126
• US Class Current: 257/684
• CPC Class Codes: B81C 1/00269 Bonding of solid lids or wafers to the substrate
• CPC Class Codes: B81C 2203/0118 Bonding a wafer on the substrate, i.e. where the cap consists of another wafer
• CPC Class Codes: B81C 2203/019 characterised by the material or arrangement of seals between parts
• CPC Class Codes: H01L 2224/0401 Bonding areas specifically adapted for bump connectors, e.g. under bump metallisation [UBM]
• CPC Class Codes: H01L 2224/13144 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/29035 covering only the peripheral area of the surface to be connected
• CPC Class Codes: H01L 2224/29111 Tin [Sn] as principal constituent
• CPC Class Codes: H01L 2224/29144 Gold [Au] as principal constituent
• CPC Class Codes: H01L 2224/81 using a bump connector
• CPC Class Codes: H01L 2224/81193 wherein the bump connectors are disposed on both the semiconductor or solid-state body and another item or body to be connected to the semiconductor or solid-state body
• CPC Class Codes: H01L 2224/81203 Thermocompression bonding, e.g. diffusion bonding, pressure joining, thermocompression welding or solid-state welding
• CPC Class Codes: H01L 2224/81895 between electrically conductive surfaces, e.g. copper-copper direct bonding, surface activated bonding
• CPC Class Codes: H01L 2224/83 using a layer connector
• CPC Class Codes: H01L 2224/83805 involving forming a eutectic alloy at the bonding interface
• CPC Class Codes: H01L 2224/9211 Parallel connecting processes
• CPC Class Codes: H01L 23/10 characterised by the material or arrangement of seals between parts, e.g. between cap and base of the container or between leads and walls of the container
• CPC Class Codes: H01L 24/13 of an individual bump connector
• CPC Class Codes: H01L 24/16 of an individual bump connector
• CPC Class Codes: H01L 24/29 of an individual layer connector
• CPC Class Codes: H01L 24/32 of an individual layer connector
• CPC Class Codes: H01L 24/81 : using a bump connector
• CPC Class Codes: H01L 24/83 : using a layer connector
• CPC Class Codes: H01L 24/92 : Specific sequence of method steps
• 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 2924/00011 : Not relevant to the scope of the group, the symbol of which is combined with the symbol of this group
• 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 2924/01079 : Gold [Au]
• CPC Class Codes: H01L 2924/01322 : Eutectic Alloys, i.e. obtained by a liquid transforming into two solid phases
• CPC Class Codes: H01L 2924/1461 : MEMS

Abstract

A sealing and bonding material structure for joining semiconductor wafers having monolithically integrated components. The sealing and bonding material are provided in strips forming closed loops. There are provided at least two concentric sealing strips on one wafer. The strips are laid out so as to surround the component(s) on the wafers to be sealed off when wafers are bonded together. The material in the strips is a material bonding the semiconductor wafers together and sealing off the monolithically integrated components when subjected to force and optionally heating. A monolithically integrated electrical and/or mechanical and/or fluidic and/or optical device including a first substrate and a second substrate, bonded together with the sealing and bonding structure, and a method of providing a sealing and bonding material structure on at least one of two wafers and applying a force and optionally heat to the wafers to join them are described.

Claims

1. A sealing and bonding material structure for joining semiconductor wafers having monolithically integrated components, the sealing and bonding material being provided in strips forming closed loops, comprising:

at least two concentric sealing strips (10, 12) on one wafer (16), a first (10) of said concentric sealing strips surrounding a second (12) of said concentric sealing strips such that said second of said concentric sealing strips is inside a perimeter of said first of said concentric sealing strips,

said concentric sealing strips (10, 12) being laid out so as to surround the component(s) (18) on the wafers to be sealed off when wafers are bonded together,

the material(s) in said concentric sealing strips (10, 12) being capable of bonding said semiconductor wafers together and provide a seal for the monolithically integrated components, when subjected to force,

a compressibility of the concentric sealing strips vary along an extension of the sealing structure on the substrate to accommodate topography on the substrates when bonded together, and

the material(s) in the concentric sealing strips configured to permit thermo-compression bonding or eutectic bonding.

2. The sealing and bonding material structure as claimed in claim 1, wherein cross-bars of sealing material connect said concentric sealing strips at selected intervals along said concentric sealing strips.

3. The sealing and bonding material structure as claimed in claim 1, wherein a compressibility of the cross-bars vary along the extension of the sealing structure on the substrate to accommodate topography on the substrates when bonded together.

4. The sealing and bonding material structure as claimed in claim 1, wherein the compressibility of the concentric sealing strips corresponds to a width and/or thickness of the concentric sealing strips.

5. The sealing and bonding material structure as claimed in claim 4, wherein the concentric sealing strips in said structure are slightly wider in a region where the concentric sealing strips extend between areas exhibiting no topography, than where the concentric sealing strips cross areas exhibiting topography.

6. The sealing and bonding material structure as claimed in claim 3, wherein a compressibility of the cross-bars corresponds to a width and/or thickness of the cross-bars.

7. The sealing and bonding material structure as claimed in claim 3, wherein a compressibility of the cross-bars corresponds to a quantity of the cross-bars per unit area of said structure.

8. The sealing and bonding material structure as claimed in claim 3, wherein a compressibility of the structure corresponds to a layout of the intersections between the cross-bars and the concentric sealing strips.

9. The sealing and bonding material structure as claimed in claim 3, wherein corners and “

T”

-branches where the cross-bars connect to the concentric sealing strips exhibit a geometry such that there is provided curved or rounded sections exhibiting a radius of curvature, whereby a width of individual concentric sealing strips is essentially the same at every point along the entire structure.

10. The sealing and bonding material structure as claimed in claim 1, wherein the material(s) is/are one of the group consisting of:

gold (Au), gold-tin (AuSn), a combination of gold and silicon, poly-silicon, silicon and germanium Au/poly-SiGe, and Au/poly-Si.

11. The sealing and bonding material structure as claimed in claim 1, wherein the material of said concentric sealing strips comprise two material components, a first component being silicon and a second component being gold (Au).

12. The sealing and bonding material structure as claimed in claim 1, wherein the material(s) in said concentric sealing strips (10, 12) is/are capable of bonding said semiconductor wafers together and provide a seal for the monolithically integrated components, when subjected to force and also optionally heating.

13. The sealing and bonding material structure as claimed in claim 4, wherein the concentric sealing strips in said structure are slightly wider in a region where the concentric sealing strips extend between routing lines than where the concentric sealing strips cross the routing lines.