Torsional shear testing for semiconductor surface bonds
A method of testing semiconductor surface bonds includes centering a torsional shear tool with respect to a first die having a surface bond to a wafer, clamping the first die using the torsional shear tool, applying a torsional load to the first die with respect to the wafer using the torsional shear tool, and measuring a torque value associated with the torsional load.
1 . A method of testing semiconductor surface bonds, the method comprising:
centering a torsional shear tool with respect to a first die having a surface bond to a wafer;
clamping the first die using the torsional shear tool, wherein clamping the first die further comprises at least one of: clamping the first die with two opposing jaws; and clamping the first die with two pairs of opposing jaws, wherein each pair of opposing jaws is orthogonal to each other;
applying a torsional load to the first die with respect to the wafer using the torsional shear tool; and
measuring a torque value associated with the torsional load.
2 . The method of claim 1 , wherein the wafer is bonded to a plurality of dies including the first die.
3 . The method of claim 2 , further comprising performing the method of claim 1 for at least a subset of the plurality of dies to measure torque values respectively associated with the subset, wherein the torque values measured are characteristic for the wafer.
4 . The method of claim 1 , wherein the torsional load is a monotonically increasing torque and wherein the torque value is a failure torque for the first die, the failure torque being indicative of a bond strength of the surface bond.
5 . The method of claim 1 , wherein the torsional load is a cyclic torque and wherein the torque value is associated with a number of cycles of the cyclic torque to failure of the surface bond.
6 . The method of claim 5 , wherein the number of cycles of the cyclic torque to failure of the surface bond is indicative of a fatigue strength of the surface bond.
7 . The method of claim 1 , further comprising normalizing the torque value to a bond area associated with the surface bond to calculate a bond energy value.
8 . A method of testing semiconductor surface bonds, the method comprising:
centering a torsional shear tool with respect to a first wafer portion having a surface bond to a second wafer portion, wherein the second wafer portion is held fixed with respect to the torsional shear tool;
clamping the first wafer portion using the torsional shear tool;
applying a torsional load to the first wafer portion with respect to the second wafer portion using the torsional shear tool; wherein clamping the first wafer portion and applying the torsional load further comprise clamping with jaws, the jaws comprising at least one of: two opposing jaws; and two pairs of opposing jaws, wherein each pair of opposing jaws are orthogonal to each other; and
measuring a torque value associated with the torsional load.
9 . The method of claim 8 , wherein the torsional load is a monotonically increasing torque, and wherein the torque value is a failure torque for the surface bond, the failure torque being indicative of a bond strength of the surface bond.
10 . The method of claim 8 , wherein the torsional load is a cyclic torque, and wherein the torque value is associated with a number of cycles of the cyclic torque to failure of the surface bond.
11 . The method of claim 10 , wherein the number of cycles of the cyclic torque to failure of the surface bond is indicative of a fatigue strength of the surface bond.
12 . The method of claim 8 , wherein the first wafer portion and the second wafer portion are separated from two surface-bonded wafers after the surface bond is formed.
13 . The method of claim 12 , further comprising repeating the method of claim 10 for a plurality of first wafer portions respectively surface bonded to second wafer portions, wherein the respective torque values measured are characteristic for the two surface-bonded wafers.
14 . A torsional shear tool for testing bond strength of semiconductor surface bonds, the torsional shear tool comprising:
a frame fixed to a spindle enabled to apply torque to the frame;
a sensor coupled to the spindle and enabled to measure a torque value of the torque being applied; and
at least one pair of opposing jaws coupled to the frame, the opposing jaws enabled to clamp a semiconductor die at vertical edges of the semiconductor die and transmit the torque applied by the spindle to the semiconductor die,
wherein when the semiconductor die has a surface bond to a substrate that is held stationary with respect to the torsional shear tool, the spindle and opposing jaws are enabled to apply a torque value of the torque sufficient to break the surface bond, wherein the torque value is applied in-plane to the surface bond.
15 . The torsional shear tool of claim 14 , wherein the torque value is selected from one of: a monotonically increasing torque; and a cyclic torque.
16 . The torsional shear tool of claim 14 , wherein the at least one pair of opposing jaws comprises jaw pads configured to clamp a semiconductor die from a side face of the semiconductor die.
17 . The torsional shear tool of claim 14 , wherein the at least one pair of opposing jaws comprises jaw pads configured to clamp a semiconductor die from a side face and a top face of the semiconductor die.
18 . The torsional shear tool of claim 14 , wherein a width of at least one of the opposing jaws tapers.