Carrier for bonding a semiconductor chip onto and a method of contracting a semiconductor chip to a carrier
A carrier ( 100 ) for bonding a semiconductor chip ( 114 ) onto is provided, wherein the carrier ( 100 ) comprises a die pad ( 101 ) and a plurality of contact pads ( 102 ), wherein each of the plurality of contact pads ( 102 ) comprises an electrically conductive multilayer stack, wherein the electrically conductive multilayer stack comprises a surface layer ( 109 ), a first buffer layer, and a first conductive layer ( 108 ). Furthermore, the first buffer layer comprises a material adapted to prevent diffusion of material of the surface layer ( 109 ) into the first conductive layer ( 108 ), and at least two of the contact pads ( 102 ) has an ultrafine pitch relative to each other.
1. A carrier for bonding a semiconductor chip onto, the carrier comprising:
a die pad; and
a plurality of contact pads,
wherein the die pad and each of the plurality of contact pads comprises an electrically conductive multilayer stack, wherein the electrically conductive multilayer stack comprises a surface layer, a barrier layer, and a first conductive layer;
wherein the barrier layer comprises a material adapted to prevent diffusion of material of the surface layer into the first conductive layer;
wherein both each of the plurality of contact pads and the die pad comprise an adhesion layer, a second conductive layer and a buffer layer;
wherein at least two of the contact pads have an ultrafine pitch relative to each other.
2. The carrier according to claim 1 ,
wherein the plurality of contact pads are arranged in at least two rings around the die pad.
3. The carrier according to claim 2 ,
wherein at least some of the contact pads in a first ring of the at least two rings are located in a staggered position with respect to their neighbouring contact pads in a second ring of the at least two rings.
4. The carrier according to claim 1 , wherein the barrier layer comprises palladium.
5. The carrier according to claim 1 , wherein the thickness of the barrier layer is at least 0.1 micrometer.
6. The carrier according to claim 1 ,
wherein the die pad comprises a main portion and an edge portion, wherein the main portion comprises a stack of the first conductive layer and the surface layer, while the edge portion comprises a second multilayer stack of an adhesion layer, a second conductive layer, a buffer layer, the first conductive layer and the surface layer.
7. The carrier according to claim 6 ,
wherein the adhesion layer comprises a material which is specific for adhesion to copper and/or a material specific for adhesion to copper is applied onto the adhesion layer.
8. A semiconductor chip package, comprising:
a carrier according to claim 1 ;
a semiconductor chip; and
an encapsulation,
wherein the semiconductor chip has a first and an opposite, second side with a plurality of bond pads on the first side;
wherein the semiconductor chip is attached with its second side to the die pad and wherein the at least one contact pad is electrically coupled to one of the plurality of bond pads of the semiconductor chip; and
wherein the encapsulation encapsulates the semiconductor chip and mechanically anchors the die pad and the plurality of contact pads, while a surface of the contact pads is exposed from the encapsulation to constitute terminals.
9. The semiconductor chip package according to claim 8 ,
wherein the die pad has a surface that is exposed from the encapsulation, which surface is divided into a plurality of islands.
10. The semiconductor chip package according to claim 8 ,
wherein the multilayer stack of at least some of the plurality of contact pads comprise further:
a buffer layer;
a second conductive layer; and
an adhesive layer.
11. The semiconductor chip package according to claim 10 ,
wherein the at least some of the plurality of contact pads comprises a portion in the second conductive layer that laterally extends beyond the corresponding terminal.
12. A method of contacting a semiconductor chip to a carrier, the method comprising:
providing a carrier comprising a die pad, a plurality of contact pads, wherein at least one of the contact pad and the die pad comprises:
an electrically conductive multilayer stack of a surface layer, a barrier layer, and a first conductive layer, wherein the barrier layer is arranged between the first conductive layer and the surface layer, and both each of the plurality of contact pads and the die pad comprise an adhesion layer, a second conductive layer and a buffer layer;
an ultrafine pitch relative to another one of the plurality of contact pads, and
wherein the barrier layer comprises a material adapted to prevent diffusion of material of the surface layer into the first conductive layer;
attaching a semiconductor chip onto the die pad, wherein the semiconductor chips comprises a plurality of bond pads; and
contacting at least one bond pad with the at least one contact pad.
13. The method according to claim 12 ,
wherein the contacting is done by a soldering procedure.
14. The method according to claim 13 ,
wherein use is made of stencil soldering.
15. The method according to claim 13 ,
wherein a leadfree solder is used.
16. The method according to claim 15 ,
wherein the leadfree solder comprises tin, silver, copper and/or an alloy thereof.