Inline measurement of molding material thickness using terahertz reflectance
A method including emitting a terahertz beam from a light source at a layer of molding material; detecting a reflectance of the beam; and determining a thickness of the layer of molding material. A system including a panel supporter operable to support a panel including a plurality of substrates arranged in a planar array; a light source operable to emit a terahertz beam at a panel on the panel supporter; a detector operable to detect a reflection of a terahertz beam emitted at a panel; and a processor operable to determine a thickness of a material on the panel based on a time delay for an emitted terahertz beam to be detected by the detector.
1. A method comprising:
emitting a terahertz beam from a light source at a layer of molding material comprising an organic resin on an integrated circuit substrate, wherein terahertz light can penetrate each of the molding material and the substrate producing a first reflectance at an air/molding material interface, a second reflectance at a molding material/substrate interface and a third reflectance from the substrate;
detecting the second reflectance of the beam with a time delay; and
determining a thickness of the layer of molding material.
2. The method of claim 1 , wherein determining a thickness of the layer of molding material comprises determining a time delay for the beam to travel through the layer of material.
3. The method of claim 2 , wherein a thickness of the layer of molding material is determined by the formula:
Thickness
=
Time
Delay
×
Speed
of
the
beam
in
vacuum
Refractive
Index
of
the
molding
material
.
4. The method of claim 1 , wherein the molding material comprises a non-conductive material.
5. The method of claim 1 , wherein the molding material comprises a non-conductive polymer material.
6. The method of claim 1 , wherein the layer of molding material is disposed on a die.
7. The method of claim 6 , wherein the die is attached to a substrate.
8. A method comprising:
coupling an integrated circuit die to a substrate;
dispensing an amount of molding material comprising an organic resin onto the die;
determining a time delay for a terahertz beam emitted at the amount of molding material to travel through the molding material; and
determining a thickness of the amount of molding material, wherein determining a thickness is based on the time delay.
9. The method of claim 8 , wherein the thickness of the layer of molding material is determined by the formula:
Thickness
=
Time
delay
×
speed
of
beam
in
vacuum
refractive
index
of
the
molding
material
.
10. The method of claim 8 , wherein the molding material comprises a non-conductive material.
11. The method of claim 8 , wherein the molding material comprises a non-conductive polymer material.
12. The method of claim 8 , wherein the molding material embeds the die.
13. The method of claim 8 , wherein the substrate comprises a single unit of a panel of multiple units, the method further comprising:
singulating the substrate from the panel.
14. The method of claim 8 , further comprising:
comparing the thickness of the amount of molding material to a predetermined threshold.
15. The method of claim 14 , further comprising:
modifying the amount of molding material dispensed onto subsequent dice based on the comparison to the predetermined threshold.