# US 12,113,331 B2 · System and apparatus for sequential transient liquid phase bonding

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- Number: US 12,113,331 B2
- Document ID: US12113331B2
- Status: Granted
- Kind: B2
- Application number: 18/210,770
- Filed: 2023-06-16
- Published: 2023-10-12
- Granted: 2024-10-08
- Earliest claimed: 2021-10-15
- Assignees: Aeva, Inc.
- Applicants: Aeva, Inc.
- Inventors: Zhizhong Tang; Pradeep Srinivasan; Kevin Masuda; Wenjing Liang
- Web page: https://patentgrep.com/patent/US12113331B2

## CPC

- B23K 1/0016: {Soldering of electronic components}
- H01S 5/0237: by soldering
- B23K 1/0056: {soldering by means of beams, e.g. lasers, electron beams [EB]}
- B23K 20/00: Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating
- B23K 20/233: without ferrous layer
- B23K 20/24: Preliminary treatment
- H01S 5/0216: {using an intermediate compound, e.g. a glue or solder}
- H01S 5/4025: {Array arrangements, e.g. constituted by discrete laser diodes or laser bar (H01S5/42 takes precedence)}
- B23K 2101/36: Electric or electronic devices
- B23K 2101/40: Semiconductor devices
- B23K 2103/08: Non-ferrous metals or alloys
- H01S 5/021: {Silicon based substrates}
- H10W 72/013: {of die-attach connectors}
- H10W 72/01335: {by plating, e.g. electroless plating or electroplating}
- H10W 72/01338: {in gaseous form, e.g. by CVD or PVD}
- H10W 72/01365: {Thermally treating (reflowing H10W72/01357)}
- H10W 72/0198: {batch processes}
- H10W 72/0711: {Apparatus therefor}
- H10W 72/07141: {Means for applying energy, e.g. ovens or lasers}
- H10W 72/07178: {Means for aligning}
- H10W 72/073: {of die-attach connectors}
- H10W 72/07311: {Treating the bonding area before connecting, e.g. by applying flux or cleaning}
- H10W 72/07323: {Active alignment, e.g. using optical alignment using marks or sensors}
- H10W 72/07331: {Connecting techniques}
- H10W 72/07336: {Soldering or alloying}
- H10W 72/07355: {changes in materials}
- H10W 72/322: {Multilayered die-attach connectors, e.g. a coating on a top surface of a core}
- 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 72/952: {comprising metals or metalloids, e.g. PbSn, Ag or Cu}
- H10W 90/734: {between a chip and a stacked insulating package substrate, interposer or RDL}
- 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
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

Embodiments of the present disclosure include method for sequentially mounting multiple semiconductor devices onto a substrate having a composite metal structure on both the semiconductor devices and the substrate for improved process tolerance and reduced device distances without thermal interference. The mounting process causes “selective” intermixing between the metal layers on the devices and the substrate and increases the melting point of the resulting alloy materials.

## Claims

### Claim 1

A method for performing sequential bonding, said method comprising:
receiving a substrate having a plurality of receiving pads to a stage, wherein a first and second receiving pads of said plurality of receiving pads each comprise a first metal alloy;
attaching a first semiconductor chip to said first receiving pad using a first pickup head, said first semiconductor chip comprising a first metal layer;
raising a temperature of said first semiconductor chip using a first heating unit coupled to said first pickup head according to a first temperature profile to cause intermixing of said first metal layer on said first semiconductor chip and said first metal alloy of said first receiving pad to form a second metal alloy having a higher melting point than said first metal alloy;
attaching a second semiconductor chip to said second receiving pad using a second pickup head, said second semiconductor chip comprising a second metal layer; and
raising a temperature of said second semiconductor chip by a second heating unit coupled to said second pickup head according to a second temperature profile to cause intermixing of said second metal layer on said second semiconductor chip and said first metal alloy of said second receiving pad to form a third metal alloy having a higher melting point than said first metal alloy;
wherein said first predetermined temperature profile comprises temperature set points and time durations and is substantially similar to said second predetermined temperature profile.

### Claim 2 (depends on 1)

The method of claim 1, wherein said first heating unit is integrated with said first pickup head and said second heating unit is integrated with said second pickup head.

### Claim 3 (depends on 1)

The method of claim 1, wherein said first pickup head and said second pickup head are configured to operate independent of each other.

### Claim 4 (depends on 1)

The method of claim 1, wherein said first pickup head and said second pickup head are configured to operate with an alternating mode to avoid interference.

### Claim 5 (depends on 1)

The method of claim 1, wherein said second pickup head attaches said second semiconductor chip based on a measurement from said first semiconductor chip via said first pickup head.

### Claim 6 (depends on 1)

The method of claim 1, wherein said second semiconductor chip comprises a laser and said first semiconductor chip comprises a photo-detector.

### Claim 7 (depends on 1)

The method of claim 1, wherein said second semiconductor chip comprises a light emitting diode and said first semiconductor chip comprises a photo-detector.

### Claim 8 (depends on 1)

The method of claim 1, wherein said second pickup head attaches said second semiconductor chip based on a measurement on said second semiconductor chip caused by a light signal generated from said first semiconductor chip.

### Claim 9 (depends on 1)

The method of claim 1, wherein said second semiconductor chip comprises a photo-detector and said first semiconductor chip comprises a laser.

### Claim 10 (depends on 1)

The method of claim 1, wherein said second semiconductor chip comprises an array of photo-detectors and said first semiconductor chip comprises an array of optoelectronic devices.

### Claim 11 (depends on 1)

The method of claim 1, wherein said substrate comprises silicon.

### Claim 12 (depends on 1)

The method of claim 1, wherein said substrate comprises one or more integrated optical filters.

### Claim 13 (depends on 1)

The method of claim 1, wherein said substrate comprises one or more integrated optical combiners.

### Claim 14 (depends on 1)

The method of claim 1, wherein said substrate comprises one or more integrated optical couplers.

### Claim 15 (depends on 1)

The method of claim 1, wherein said substrate comprises one or more integrated optical waveguides.

### Claim 16 (depends on 1)

The method of claim 1, wherein said substrate comprises one or more integrated heaters for local temperature controls during operation.

### Claim 17 (depends on 1)

The method of claim 1, wherein said first metal alloy comprises gold, tin, and copper.

### Claim 18 (depends on 1)

The method of claim 1, wherein said first metal alloy comprises gold and germanium.

### Claim 19 (depends on 1)

The method of claim 1, wherein said first metal alloy comprises platinum and tin.

### Claim 20 (depends on 1)

The method of claim 1, wherein said first metal comprises gold.