Wafer pedestal with contact array

1. A wafer heating pedestal, comprising:

a plate having a carrying surface for supporting a wafer and a bottom surface opposite to the carrying surface, wherein the bottom surface is provided with a plurality of contact pads; and

a shaft connecting to the bottom surface of the plate and holding a contact array being in contact with the plurality of the contact pads, the contact array including a plurality of contact columns,

wherein each of the plurality of the contact columns includes a pillar, a sheath cladding over the pillar and a spring exposed between the pillar and the sheath, wherein the pillar is configured to move relatively to the sheath in a reciprocation way, the pillar has a contact cap provided on a top thereof for contacting with the corresponding one of the contact pads, and two ends of the spring connect to the contact cap and the sheath respectively to provide a bias force therebetween.

2. The wafer heating pedestal as claimed in claim 1 , wherein the plate includes one more heating assemblies and one more sensing units embedded therein, and each of the one or more heating assemblies defines a heating zone of the plate, each of the one or more heating assemblies electrically connects to at least three contact pads.

3. The wafer heating pedestal as claimed in claim 2 , wherein the plate has a plurality of vias formed therein and connecting the heating assemblies and the contact pads.

4. The wafer heating pedestal as claimed in claim 1 , wherein the shaft holds a base positioning the plurality of contact columns, wherein the sheath of each of the plurality of contact columns is received in the base.

5. The wafer heating pedestal as claimed in claim 2 , wherein the plurality of the contact columns of the contact array electrically couples to a plurality of metal rods in order to deliver signal associated with said heating assembly and said sensing unit.

6. The wafer heating pedestal as claimed in claim 1 , wherein the shaft connects to a cooling member which extends from an interior of the shaft to an exterior of the shaft.

7. The wafer heating pedestal as claimed in claim 6 , wherein the cooling member connects to a bottom of the shaft, the cooling member has an upper part and a lower part wherein the upper part extends into the shaft while the lower part is exposed to the outside of the shaft and has plural cooling paths.

8. The wafer heating pedestal as claimed in claim 6 , wherein the cooling member is configured to contact with a plurality of metal rods to transfer the heat of the plurality of metal rods.

9. The wafer heating pedestal as claimed in claim 1 , wherein the contact array has thirty six contact columns.

10. A processing chamber, comprising the wafer heating pedestal as claimed in claim 6 , wherein a portion of the cooling member is exposed to an interior of the processing chamber.