Patent WO-2023088705-A3 (WO)
Inventor: Müller Klaus
IPC: H01L21/60
Filed: 2022-11-07
Abstract: The invention relates to a semiconductor chip (1) having at least two electrical contact points (6) arranged on a main surface (5) of the semiconductor chip (1), wherein a metallic reservoir layer (10) (e.g. Au) is applied over or on the entire surface of the electrical contact point (6). A diffusion barrier layer (11) can be applied to the metallic reservoir layer (10) in direct contact, which diffusion barrier layer is arranged set back relative to the metallic reservoir layer (10), so that the metallic reservoir layer (10) is partially freely accessible, the diffusion barrier layer (11) forming an adhesion surface for a solder (21) and/or a first solder component of the solder (21) and/or a second solder component of the solder (21). The diffusion barrier layer (11) can comprise two individual layers (11', 11''), namely an adhesion-promoting individual layer (11') (e.g. Ti) and an individual layer (11'') (e.g. Ni or Pt) which together particularly account for the diffusion barrier properties of the diffusion barrier layer (11). Alternatively, a separation layer (14) (e.g., Ti) can be applied to the metallic reservoir layer (10) in direct contact, which separation layer is arranged set back relative to the metallic reservoir layer (10) so that the metallic reservoir layer (10) is partially freely accessible, and the separation layer (14) can dissolve in the solder (21) and/or a first solder component of the solder (21) and/or a second solder component of the solder (21). A metallic top layer (13) (e.g. Au) can be arranged over or on the diffusion barrier layer (11) or over or on the separation layer (14), which preferably prevents the material lying below from oxidation. The metallic reservoir layer (10), the metallic top layer (13) and/or at least one solder component can comprise the same material. The reservoir layer (10) below the separation layer (14) can comprise a first solder component (e.g. Au), and over or on the separation layer (14) a solder component layer (15) comprising the second solder component (e.g. Sn) is arranged and over or on the solder component layer (15) another separation layer (16) (e.g. Ti) is arranged. The semiconductor chip (1) can be a radiation-emitting flip-chip semiconductor chip (1) (such as a laser diode chip or a light-emitting diode chip). The first solder component can be Au and the second solder component can be Sn. The separation layer (14) and/or the diffusion barrier layer (11) can be centrally located on the metallic reservoir layer (10) so that lateral zones (12) of the metallic reservoir layer (10) are freely accessible. The contact point (6) can comprise an adhesion-promoting individual layer (9), (e.g. Ti) and an electrical contact layer (8) (e.g. Cu, Pt, Au, Ag, Al). The semiconductor layer (1) can be connected to a connection carrier (17) having two electrical connection points (18), and, if a diffusion barrier layer (11) is applied to the metallic reservoir layer (10), liquid solder (21) comes in contact with the metallic reservoir layer (10) and solidifies, or, if a separation layer (14) is applied to the metallic reservoir layer (10), the first solder component and/or the second solder component are liquefied, and the separation layer (14) dissolves in the first solder component and/or the second solder component. Both methods allow reducing short-circuits between the electrical contact points (6) of the semiconductor chip (1) since the liquid melt of the solder (21) wets the exposed zones (12) of the metallic reservoir layer (10) and can solidify in these zones. The connection carrier (17) can be heated so that the layer sequence (7) on the electrical contact points (6) of the semiconductor chip (1) is warmed up starting from the connection carrier (17). The electrical connection point (18) of the connection carrier (17) can have an electrical contact layer (8) over or on which a diffusion barrier (11) is arranged which forms an adhesion surface for the solder (21) and/or over or on which a metallic top layer (13) is arranged.