Sintered metal flip chip joints
An integrated circuit die may be fabricating to have a plurality of contacts. A metal post may be formed on each of the plurality of contacts. A plurality of bumps may be formed on a plurality of contact regions of a leadframe or on the posts, in which the plurality of bumps are formed with a material that includes metal nanoparticles. The IC die may be attached to the leadframe by aligning the metal posts to the leadframe and sintering the metal nanoparticles in the plurality of bumps to form a sintered metal bond between each metal post and corresponding contact region of the leadframe.
1 . A method for fabricating an integrated circuit, the method comprising:
forming metal interconnects on at least one of: first contact regions on a semiconductor die, or second contact regions of a metallic leadframe of the integrated circuit, in which the metal interconnects include metal nanoparticles, wherein the metal nanoparticles comprise copper nanoparticles and either graphene nanoparticles or graphite nanoparticles;
coupling the metal interconnects between the first contact regions and the second contact regions;
sintering the metal nanoparticles to form a sintered metal bond between the metal interconnects and at least one of the first or second contact regions.
2 . The method of claim 1 , wherein the sintering the metal bond is porous.
3 . The method of claim 2 , wherein the sintered metal bonds each has a porosity ranging from 0%-50%.
4 . The method of claim 1 , wherein a first portion of the metal nanoparticles is formed on the first contact regions, and a second portion of the metal nanoparticles is formed on the second contact regions.
5 . The method of claim 1 , wherein forming the metal interconnects includes depositing droplets of the metal nanoparticles with an inkjet printer.
6 . The method of claim 1 , wherein sintering the metal nanoparticles includes at least one of: heating the metal nanoparticles, illuminating the metal nanoparticles, or exposing the metal nanoparticles to an acid.
7 . The method of claim 1 , wherein forming the metal interconnects comprises:
forming metal posts on the first contact regions as first parts of the metal interconnects; and
forming bumps of the metal nanoparticles on the metal posts as second parts of the metal interconnects; and
wherein coupling the metal interconnects between the first contact regions and the second contact regions includes bringing the bumps of the metal nanoparticles and the second contact regions into contact.
8 . The method of claim 1 , further comprising:
forming metal posts on the first contact regions as the metal interconnects; and
forming bumps of the metal nanoparticles on the second contact regions,
wherein coupling the metal interconnects between the first contact regions and the second contact regions includes bringing the bumps of the metal nanoparticles and the second contact regions into contact.
9 . The method of claim 1 , further comprising:
forming columns of the metal nanoparticles on the first contact regions as the metal interconnects,
wherein coupling the metal interconnects between the first contact regions and the second contact regions includes bringing the columns of the metal nanoparticles and the second contact regions into contact.
10 . The method of claim 1 , further comprising:
forming columns of the metal nanoparticles on the second contact regions as the metal interconnects,
wherein coupling the metal interconnects between the first contact regions and the second contact regions includes bringing the columns of the metal nanoparticles and the first contact regions into contact.
11 . The method of claim 1 , wherein the sintering the metal nanoparticles causes a portion of the metal nanoparticles to diffuse into at least one of the first or second contact regions.
12 . The method of claim 1 , wherein the semiconductor die is flip chip connected to the metallic leadframe.
13 . The method of claim 1 , further comprising mounting the integrated circuit on a circuit board.
14 . The method of claim 6 , wherein the sintering the metal nanoparticles comprises illuminating the metal nanoparticles.
15 . The method of claim 1 , further comprising encapsulating the semiconductor die, the metallic leadframe, and the metal interconnects with a molding compound, at least a portion of the molding compound between the semiconductor die and the metallic leadframe.
16 . A method comprising:
forming metal interconnects on at least one of: first contact regions on a semiconductor die, or second contact regions of a metallic leadframe of an integrated circuit, in which the metal interconnects include copper oxide nanoparticles;
coupling the metal interconnects between the first contact regions and the second contact regions; and
forming a metal bond between the metal interconnects and at least one of the first or second contact regions, wherein the forming the metal bond comprises reducing the copper oxide nanoparticles to copper nanoparticles.
17 . A method comprising:
forming metal interconnects on at least one of: first contact regions on a semiconductor die, or second contact regions of a metallic leadframe of an integrated circuit, in which the metal interconnects include metal nanoparticles, wherein the metal nanoparticles comprise a sacrificial nanoparticles;
coupling the metal interconnects between the first contact regions and the second contact regions;
sintering the metal nanoparticles to bond between the metal interconnects and at least one of the first or second contact regions; and
removing the sacrificial nanoparticles.
18 . The method of claim 17 , wherein removing the sacrificial nanoparticles is performed while sintering the metal nanoparticles.
19 . The method of claim 17 , wherein removing the sacrificial nanoparticles is performed after sintering the metal nanoparticles.
20 . The method of claim 17 , wherein the sacrificial nanoparticles include a polymer or silica.