Method of forming solder bumps onto an integrated circuit device

A method for transferring solder bumps onto terminal pads on a semiconductor substrate for an integrated circuit devices comprising the steps of:

• (1) providing a plate having a planar surface which is non-wettable relatively to molten solder and is a size sufficient enough to cover all of the terminal pads on the semiconductor substrate;
• (2) providing a mask having a first surface and a second surface opposite to the first surface, the mask having a plurality of through-holes, the respective cross-sectional areas of which increase, step wise, from the first surface of the mask to the second surface thereof, the mask being of a size sufficient to cover all of the terminal pads on the semiconductor substrate;
• (3) pressing the second surface of the mask against the planar surface of the plate;
• (4) depositing solder over the mask by vapor phase deposition such that a solder deposit is formed on the planar surface of the plate within each of the through-holes and without contacting an inside wall thereof, the respective solder deposits within the plurality of through-holes being of uniform height relatively to, and throughout, the planar surface;
• and
• (5) separating the mask from the planar surface of the plate such that the respective solder deposits within the plurality of through-holes remain on the planar surface of the plate.

A method for fabricating a semiconductor substrate having a single solder bump on each of plural terminal pads thereon, for an integrated circuit comprising the steps of:

• (1) providing a plate having a planar surface which is non-wettable to molten solder and is of a size sufficient to cover all of the terminals pads on the semiconductor substrate;
• (2) providing a mask having a first surface and a second surface opposite to the first surface, the mask having a plurality of through-holes, the respective cross-sectional areas of which increase, step wise, from the first surface of the mask to the second surface thereof, the mask being of a size sufficient to cover all of the terminal pads on the semiconductor substrate;
• (3) pressing the second surface of the mask against the planar surface of the plate;
• (4) depositing solder over the mask by vapor phase deposition such that a solder deposit is formed on the planar surface of the plate, within each of the through-holes and without contacting an inside wall thereof, the respective solder deposits within the plurality of through-holes being of a uniform height relatively to and throughout the planar surface;
• and
• (5) separating the mask from the planar surface of the plate such that the respective solder deposits within the plurality of through-holes remain on the planar surface of the plate thereby to produce a solder bump transfer plate having a planar surface which is non-wettable to molten solder, solder deposits being arranged on the planar surface of the plate such that each of the solder deposits corresponds to one of the terminal pads;
• (6) coating material on an entire surface of the semiconductor substrate except the terminal pads thereon, the material having a non-wettable tendency relatively to molten solder;
• (7) positioning the solder bump transfer plate on the semiconductor substrate such that all of the solder deposits rest on the corresponding terminal pads throughout the entire surface of the semiconductor substrate;
• (8) heating the plate, as positioned on the semiconductor substrate, such that each solder deposit melts and forms a single molten solder bump on the corresponding terminal pad and molten solder not included in a corresponding molten solder bump forms molten solder balls in the material between the terminal pads;
• (9) cooling the solder bump transfer plate on the semiconductor substrate to solidify the molten solder bumps on the corresponding terminal pads and the molten solder balls in the material,
• (10) separating the solder bump transfer plate from the semiconductor substrate such that the solidified solder bumps remain firmly on the corresponding terminal pads and the solidified solder balls remain in the material;
• and
• (11) subsequently removing the material and the solder balls from the semiconductor substrate.

A method comprising the steps of:

• forming plural solder deposits on a surface of a plate, the plate surface having a non-wetting characteristic relatively to molten solder;
• coating a material on a surface of a semiconductor substrate except four plural terminal pads formed thereon, the material having a non-wettable characteristic relatively to molten solder;
• aligning the plate-and the semiconductor substrate and positioning same such that the plural solder deposits rest respectively on the plural terminal pads and, while so positioned:
• (1) melting the solder deposits such that each solder deposit forms a corresponding, individual molten solder bump on the respective terminal pad, excess molten solder not included in a molten solder bump forming molten solder balls in the material between the terminal pads;
• solidifying the molten solder bumps on the respective terminal pads and the molten solder balls in the material;
• separating the plate from the semiconductor substrate;
• and
• removing the material with the solidified solder balls therein from the semiconductor substrates.