DIE BACKSIDE METALLIZATION METHODS AND APPARATUS
Die backside metallization methods and apparatus are disclosed. In one aspect, a method of forming a die involves providing a backside metallization layer on the die prior to attaching the die to a chip carrier. Various possible attaching techniques such as a backside solder, transient liquid phase bonding, or solid state diffusion bonding may be used. The resulting apparatus may have a relatively thin bond layer that has a relatively uniform thickness. The thin bond layer having an essentially constant thickness provides good thermal properties while being resistant to delamination from thermal cycling.
1 . A method for forming a semiconductor device, comprising:
forming a metallization layer on an exterior surface of a die; and
attaching the die to a chip carrier using the metallization layer.
2 . The method of claim 1 , wherein forming the metallization layer comprises forming a metallization layer having a thickness less than approximately 20 microns (μm), but more than 0.01 μm.
3 . The method of claim 1 , wherein forming the metallization layer comprises forming a metallization layer having a thickness less than approximately 5 microns (μm) but more than 0.01 μm.
4 . The method of claim 1 , wherein forming the metallization layer comprises forming a diffusion barrier in the metallization layer.
5 . The method of claim 1 , wherein forming the metallization layer comprises forming a metallization layer from one of gold (Au), silver (Ag), copper (Cu), indium (In), bismuth (Bi), tin (Sn), lead tin (PbSn), or tin silver (SnAg).
6 . The method of claim 1 , wherein forming the metallization layer comprises forming a metallization layer from gold tin (AuSn).
7 . The method of claim 1 , wherein forming the metallization layer on the exterior surface of the die comprises forming the metallization layer on a wafer and subsequently singulating the wafer into at least the die.
8 . The method of claim 1 , wherein attaching the die comprises diffusion bonding the die to the chip carrier.
9 . The method of claim 1 , wherein attaching the die comprises thermocompression bonding the die to the chip carrier.
10 . The method of claim 1 , wherein attaching the die comprises reducing atmospheric pressure during attaching.
11 . The method of claim 8 , wherein the diffusion bonding comprises diffusion bonding at less than approximately 250° C.
12 . The method of claim 1 , wherein attaching the die comprises transient liquid phase bonding the die to the chip carrier.
13 . The method of claim 1 , wherein forming the metallization layer on the exterior surface of the die comprises electroplating the metallization layer.
14 . The method of claim 1 , wherein forming the metallization layer on the exterior surface of the die comprises electroless plating.
15 . The method of claim 1 , wherein forming the metallization layer on the exterior surface of the die comprises chemical vapor deposition (CVD).
16 . The method of claim 1 , wherein forming the metallization layer on the exterior surface of the die comprises physical vapor deposition (PVD).
17 . A semiconductor device, comprising:
a chip carrier,
a die;
a gold-free bond layer attaching the die to the chip carrier, wherein the gold-free bond layer has a relatively uniform thickness of approximately 20 microns (μm) or less but more than 0.01 μm.
18 . The semiconductor device of claim 17 , wherein the gold-free bond layer comprises one of silver (Ag), copper (Cu), indium (In), bismuth (Bi), lead tin (PbSn), or tin silver (SnAg).
19 . The semiconductor device of claim 17 , wherein the gold-free bond layer comprises free solder.
20 . The semiconductor device of claim 17 , wherein the gold-free bond layer comprises an intermetallic compound (IMC) layer.