Wafer bonding chamber with dissimilar wafer temperatures
A wafer bonding chamber is disclosed, which maintains two wafers to be bonded together at two substantially different temperatures. A lid wafer may be held at a higher temperature than a device wafer, as the device wafer may have delicate structures formed thereon, which cannot withstand higher temperatures. The lid wafer may have an adhesive bonding material formed thereon, which is melted or cured at the higher temperature. The temperature differential may be maintained by applying at least one of a heating mechanism and a cooling mechanism preferentially to one of the wafers to be bonded in the wafer bonding chamber.
1 . A wafer bonding chamber, comprising:
a plurality of fixtures, each supporting one wafer on a frontside of the fixture; and
at least one of a heating mechanism and a cooling mechanism, configured so as to maintain one of the wafers in one of the fixtures at a substantially different temperature than another wafer in another of the plurality of fixtures.
2 . The wafer bonding chamber of claim 1 , wherein the cooling mechanism comprises a stream of inert gas directed at a backside of at least one of the fixture and the wafer.
3 . The wafer bonding chamber of claim 1 , wherein the heating mechanism comprises a radiation source, wherein the radiation is directed against an exposed side of the wafer to heat the wafer.
4 . The wafer bonding chamber of claim 1 , further comprising a refrigerated coolant provided to at least one of the fixtures.
5 . The wafer bonding chamber of claim 1 , wherein the wafer bonding chamber further comprises a resistive heating structure disposed in one of the fixtures.
6 . The wafer bonding chamber of claim 4 , wherein the permeable magnetic material comprises an alloy of nickel and iron.
7 . The wafer bonding chamber of claim 1 , further comprising both a heating mechanism and a cooling mechanism, wherein the heating mechanism heats one of the wafers and the cooling mechanism comprises helium introduced into the wafer bonding chamber.
8 . The wafer bonding chamber of claim 1 , wherein the heating source comprises:
a coil of wire surrounding one of the fixtures, to which an RF signal is applied, and wherein the wafer supported in the fixture has a permeable magnetic material deposited thereon.
9 . The wafer bonding chamber of claim 8 , wherein the wafer further comprises at least one of a bonding material and a getter material disposed adjacent to the magnetically permeable material.
10 . The wafer bonding chamber of claim 8 , further comprising:
a power supply that provides an RF signal to the coil, wherein the RF signal has a frequency between about 1 kHz and 100 kHz, and a power level between about 1 watt and 500 watts.
11 . The wafer bonding chamber of claim 8 , wherein the wafer further comprises a cavity formed beneath the permeable magnetic material.
12 . The wafer bonding chamber of claim 9 , wherein the bonding material comprises one component of a metal alloy hermetic sealing material, and the another wafer comprises another component of the metal alloy hermetic sealing material.
13 . The wafer bonding chamber of claim 12 , wherein the one component comprises at least one of gold and indium, and the magnetically permeable material comprises at least one of a Ni/Fe alloy, a cobalt alloy and a manganese alloy, and has a permeability of between about 10 and 20 T.
14 . The wafer bonding chamber of claim 1 , wherein the heating source comprises:
a coil of wire embedded in one of the fixtures, to which an RF signal is applied, and wherein the wafer supported in the one of the fixtures has a permeable magnetic material deposited thereon.
15 . The wafer bonding chamber of claim 14 , wherein the wafer further comprises at least one of a getter material and a bonding material disposed adjacent to the magnetically permeable material.
16 . The wafer bonding chamber of claim 14 , wherein the getter material comprises an alloy containing at least one of vanadium, zirconium and iron, and readily absorbs contaminant gases and humidity.
17 . The wafer bonding chamber of claim 14 , further comprising:
a power supply that provides an RF signal to the coil, wherein the RF signal has a frequency between about 1 kHz and 100 kHz, and a power level between about 1 watt and 500 watts.
18 . The wafer bonding chamber of claim 17 , further comprising:
a magnetic core around which the coil is wound.
19 . The wafer bonding chamber of claim 15 , wherein the magnetically permeable material comprises at least one of a Ni/Fe alloy, a cobalt alloy and a manganese alloy, and has a permeability of between about 10 and 20 T.
20 . The wafer bonding chamber of claim 15 , wherein the getter material comprises at least one of vanadium, zirconium and iron, and readily absorbs contaminant gases and humidity.