US 2003/0157426 A1 · Glass frit wafer bonding process and packages formed thereby

Abstract

A method of glass frit bonding wafers to form a package, in which the width of the glass bond line between the wafers is minimized to reduce package size. The method entails the use of a glass frit material containing a particulate filler material that establishes the stand-off distance between wafers, instead of relying on discrete structural features on one of the wafers dedicated to this function. In addition, the amount of glass frit material used to form the glass bond line between wafers is reduced to such levels as to reduce the width of the glass bond line, allowing the overall size of the package to be minimized. To accommodate the variability associated with screening processes when low volume lines of paste are printed, the invention further entails the use of storage regions defined by walls adjacent the glass bond line to accommodate excess glass frit material without significantly increasing the width of the bond line.

Claims20

Dependent claims

A method of bonding first and second semiconductor wafers together, the method comprising the steps of:

providing a mixture of a glass frit material and a particulate filler material having a diametrical dimension;
depositing the mixture on a surface of the first wafer so as to define a bond line thereon;
mating the first and second wafers so that the bond line is between and contacts surfaces of both of the first and second wafers, the surfaces of the first and second wafers being spaced apart a stand-off distance approximately equal to the diametrical dimension of the particulate filler material;
heating the mixture to melt the glass frit material;
and then
cooling the glass frit material to form a glass bond line between the first and second wafers, the surfaces of the first and second wafers remaining approximately spaced apart by the stand-off distance.

3 more elements

A method of bonding a capping wafer to a device wafer to form a package that encloses a micromachined device formed on the device wafer, the method comprising the steps of:

forming the capping wafer to have a peripheral edge and a trench in a surface thereof, the trench being spaced inwardly from the peripheral edge so as to define a bonding surface therebetween on the capping wafer, the bonding surface being located on the capping wafer and continuous so that the bonding surface will surround the micromachined device when the capping wafer is bonded to the device wafer to form the package and enclose the micromachined device of the device wafer;
providing a glass frit paste comprising a binder, a solvent, a glass frit material, and a particulate filler material having a diametrical dimension and a higher melting temperature than the glass frit material;
screen printing the glass frit paste on the bonding surface of the capping wafer so that the glass frit paste defines a bond line on the bonding surface;
heating the glass frit paste to remove the binder and the solvent and melt the glass frit paste so that the bond line comprises the particulate filler material in a molten glass material;
resolidifying the bond line so that the particulate filler material remains dispersed in a solid glass material;
mating the device and capping wafers so that the bond line is between and contacts the bonding surface of the capping and an opposing bonding surface of the device wafer;
heating the device and capping wafers to melt the solid glass material but not the particulate filler material, a first portion of the bond line flowing into the trench and a second portion of the bond line flowing beyond the peripheral edge while a remainder of the bond line remains between the bonding surfaces of the device and capping wafers, the bonding surfaces of the device and capping wafers being spaced apart a stand-off distance approximately equal to the diametrical dimension of the particulate filler material;
and then
cooling the device and capping wafers to resolidify the bond line and form a glass bond line between the device and capping wafers, the bonding surfaces of the device and capping wafers remaining approximately spaced apart by the stand-off distance.

6 more elements

Dependencies are inferred from the claim text.

Glass frit wafer bonding process and packages formed thereby

Life of this patent

Glass frit wafer bonding process and packages formed thereby

Life of this patent

Abstract

Claims20