Verfahren zum Diffusionslöten einer Halbleitervorrichtung mittels einer Lötvorform mit Wechselndem Oberflächenprofil

Details

Veröffentlichungs-Nr.

EP4141924

Aktenzeichen

EP22193090

Anmeldetag

31. August 2022

Veröffentlichung

24. Juli 2024

Erteilung

24. Juli 2024

Rechtsraum

EP

IPC

H01L23/488H01L21/60H01L23/00B23K35/26B23K35/28

Abstract

A method of soldering a semiconductor device includes providing a substrate (102) having a first metal joining surface (106), providing a semiconductor die (104) having a second metal joining surface (114), providing a solder preform (100) having a first interface surface (110) and a second interface surface (112), arranging the solder preform (100) between the substrate (102) and the semiconductor die (104) such that the first interface surface (110) of the solder preform (100) faces the first metal joining surface (106) of the substrate (102) and such that the second interface surface (112) of the solder preform (100) faces the second metal joining surface (114) of the semiconductor die (104), and performing a mechanical pressure-free diffusion soldering process that forms a soldered joint between the substrate (102) and the semiconductor die (104) by melting the solder preform (100) and forming intermetallic phases in the solder. One or both of the first interface surface (110) and the second interface surface (112) has a varying surface profile (124) that creates voids (126) between the solder preform (100) and one or both of the substrate (102) and the semiconductor die (104) before the melting of the solder preform (100). The varying surface profile (124) may comprise a plurality of ridges (128) and channels (130) that are disposed between immediately adjacent ones of the ridges (128), wherein the channels (130) create the voids (126) in the arrangement (116) of the solder preform (100) in between the substrate (102) and the semiconductor die (104), permitting ingress and egress of the ambient atmosphere (122) within a soldering furnace (118) that contains the arrangement (116) of the solder preform (100) in between the substrate (102) and the semiconductor die (104). Performing the mechanical pressure-free diffusion soldering process may comprise a conditioning step that removes a tacking agent (108) provided between the solder preform (100) and one or both of the substrate (102) and the semiconductor die (104), wherein vapours of the tacking agent (108) may be outgassed through the channels (130). Performing the mechanical pressure-free diffusion soldering process may also comprise an activation step that introduces formic acid into the soldering furnace (118), wherein the formic acid can flow into the arrangement (116) through the channels (130) and the resulting reacted oxide can exit the arrangement (116) via the channels (130). The ridges (128) and channels (130) may have an undulating profile along a cross-section of the solder preform (100) that is orthogonal to the ridges (128).

Anmelder

Firma

Infineon Technologies Austria AG

Land

🇦🇹 Österreich

Fachgebiete