# US 2014/0154867 A1 · Method for permanently bonding wafers by a connecting layer by means of solid state diffusion or phase transformation

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- Number: US 2014/0154867 A1
- Document ID: US20140154867A1
- Status: Published application
- Kind: A1
- Application number: 14/232,911
- Filed: 2011-08-30
- Published: 2014-06-05
- Earliest claimed: 2011-08-30
- Assignees: EV Group E. Thallner GmbH
- Inventors: Klaus Martinschitz; Markus Wimplinger; Bernhard Rebhan; Kurt Hingerl
- Web page: https://patentgrep.com/patent/US20140154867A1

## CPC

- H10P 90/1914: {using bonding}
- B23K 35/001: {Interlayers, transition pieces for metallurgical bonding of workpieces}
- B23K 35/0255: {for use in welding (B23K35/0205 takes precedence)}
- B23K 35/262: {Sn as the principal constituent}
- B23K 35/302: {Cu as the principal constituent}
- H10P 10/12: {Bonding of semiconductor wafers or semiconductor substrates to semiconductor wafers or semiconductor substrates (preparing SOI wafers using bonding H10P90/1914)}
- H10W 10/181: {Semiconductor-on-insulator [SOI] isolation regions, e.g. buried oxide regions of SOI wafers}
- H10W 90/00: Package configurations
- B23K 20/021: {Isostatic pressure welding}
- B23K 20/023: {Thermo-compression bonding}
- B23K 2101/40: Semiconductor devices
- H10W 72/013: {of die-attach connectors}
- H10W 72/01338: {in gaseous form, e.g. by CVD or PVD}
- H10W 72/01351: {Changing the shapes of die-attach connectors}
- H10W 72/01361: {Chemical or physical modification, e.g. by sintering or anodisation (patterning H10W72/01351)}
- H10W 72/01371: {Cleaning, e.g. oxide removal or de-smearing}
- H10W 72/019: {of bond pads}
- H10W 72/01951: {Changing the shapes of bond pads}
- H10W 72/0198: {batch processes}
- H10W 72/07173: {Means for moving chips, wafers or other parts, e.g. conveyor belts}
- H10W 72/073: {of die-attach connectors}
- H10W 72/07311: {Treating the bonding area before connecting, e.g. by applying flux or cleaning}
- H10W 72/07331: {Connecting techniques}
- H10W 72/07332: {Compression bonding, e.g. thermocompression bonding}
- H10W 72/07336: {Soldering or alloying}
- H10W 72/07352: {changes in structures or sizes}
- H10W 72/07355: {changes in materials}
- H10W 72/321: {Structures or relative sizes of die-attach connectors}
- H10W 72/322: {Multilayered die-attach connectors, e.g. a coating on a top surface of a core}
- H10W 72/325: {Die-attach connectors having a filler embedded in a matrix}
- H10W 72/331: {Shapes of die-attach connectors}
- H10W 72/334: {Cross-sectional shape, i.e. in side view}
- H10W 72/351: {Materials of die-attach connectors}
- H10W 72/352: {comprising metals or metalloids, e.g. solders}
- H10W 72/59: Bond pads specially adapted therefor
- H10W 72/931: {Shapes of bond pads}
- H10W 72/934: {Cross-sectional shape, i.e. in side view}
- H10W 72/952: {comprising metals or metalloids, e.g. PbSn, Ag or Cu}
- H10W 80/721: {having structure or size changed during the connecting}
- H10W 80/754: {having material changed during the connecting}
- H10P: GENERIC PROCESSES OR APPARATUS FOR THE MANUFACTURE OR TREATMENT OF DEVICES COVERED BY CLASS H10
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A method for bonding of a first solid substrate to a second solid substrate which contains a first material with the following steps, especially the following sequence: formation or application of a function layer which contains a second material to the second solid substrate, making contact of the first solid substrate with the second solid substrate on the function layer, pressing together the solid substrates for forming a permanent bond between the first and second solid substrate, at least partially reinforced by solid diffusion and/or phase transformation of the first material with the second material, an increase of volume on the function layer being caused.

## Claims

### Claim 1

A method for bonding of a first solid substrate to a second solid substrate which contains a first material, the method comprising:
formation or application of a function layer containing a second material to the second solid substrate,
making contact of the first solid substrate with the second solid substrate on the function layer,
pressing together the first and second solid substrates for forming a permanent bond between the first and second solid substrates, at least partially reinforced by solid diffusion and/or phase transformation of the first material with the second material, thereby causing an increase of volume on the function layer.

### Claim 2 (depends on 1)

The method as claimed in claim 1, wherein said method further comprises forming and/or reinforcing the permanent bond by diffusion of the second material into the first material.

### Claim 3 (depends on 1)

The method as claimed in claim 1, wherein the formation of the permanent bond takes place at a temperature between room temperature and 500° C.

### Claim 4 (depends on 1)

The method as claimed in claim 1, wherein the permanent bond has a bond strength of greater than 1.5 J/m2.

### Claim 5 (depends on 1)

The method as claimed in claim 1, wherein during solid diffusion and/or phase transformation a mixed material (C) with a greater molar volume than the molar volume of the second material and of the first material is formed.

### Claim 6 (depends on 1)

The method as claimed in claim 1, wherein prior to and/or after application/formation of the function layer plasma, activation of the surfaces of the solid substrates takes place.

### Claim 7 (depends on 1)

The method as claimed in claim 1, wherein the solid diffusion and/or phase transformation is limited to a first surface layer of the first solid substrate with a maximum initial thickness D smaller than 1 μm.

### Claim 8 (depends on 1)

The method as claimed in claim 1, wherein the step of pressing together takes place at a pressure between 0.1 and 10 MPa.

### Claim 9 (depends on 8)

The method as claimed in claim 8, wherein the function layer before formation of the permanent bond has an average thickness R between 1 angstrom and 10 nm.

### Claim 10 (depends on 1)

The method as claimed in claim 1, wherein a solubility boundary of the first material for the second material during formation of the permanent bond is exceeded at least only slightly.

### Claim 11 (depends on 1)

The method as claimed in claim 1, wherein the solid diffusion take place at least predominantly as grain boundary diffusion.

### Claim 12 (depends on 2)

The method as claimed in claim 2, wherein the diffusion of the second material into the first material forms a mixed material.

### Claim 13 (depends on 3)

The method as claimed in claim 3, wherein said temperature is between room temperature and 200° C.

### Claim 14 (depends on 3)

The method as claimed in claim 3, wherein said temperature is between room temperature and 150° C.

### Claim 15 (depends on 3)

The method as claimed in claim 3, wherein said temperature is between room temperature and 100° C.

### Claim 16 (depends on 3)

The method as claimed in claim 3, wherein said temperature is between room temperature and 50° C.

### Claim 17 (depends on 3)

The method as claimed in claim 3, wherein the formation of the permanent bond takes place during a maximum 12 days.

### Claim 18 (depends on 3)

The method as claimed in claim 3, wherein the formation of the permanent bond takes place during a maximum 1 day.

### Claim 19 (depends on 3)

The method as claimed in claim 3, wherein the formation of the permanent bond takes place during a maximum 1 hour.

### Claim 20 (depends on 3)

The method as claimed in claim 3, wherein the formation of the permanent bond takes place during a maximum 15 minutes.

### Claim 21 (depends on 4)

The method as claimed in claim 4, wherein the bond strength is greater than 2 J/m2.

### Claim 22 (depends on 4)

The method as claimed in claim 4, wherein the bond strength is greater than 2.5 J/m2.

### Claim 23 (depends on 7)

The method as claimed in claim 7, wherein the maximum initial thickness D is smaller than 100 nm.

### Claim 24 (depends on 7)

The method as claimed in claim 7, wherein the maximum initial thickness D is smaller than 10 nm.

### Claim 25 (depends on 7)

The method as claimed in claim 7, wherein the maximum initial thickness D is smaller than 1 nm.

### Claim 26 (depends on 10)

The method as claimed in claim 10, wherein the solubility boundary is exceeded at no site of solid diffusion and/or phase transformation.