Composite substrate for layered heaters

1. A heater assembly for use in semiconductor processing comprising:

an application substrate being an austenitic stainless steel material;

a bonding layer;

a heater substrate secured to the application substrate by the bonding layer and by a thermal bonding process, the heater substrate being a molybdenum material; and

a functional layer being a first dielectric layer including an alumina material and disposed onto the heater substrate by a layered process,

wherein the heater substrate defines a material having a coefficient of thermal expansion that is matched to a coefficient of thermal expansion of the functional layer.

2. The heater assembly according to claim 1 , wherein the heater substrate is brazed to the application substrate.

3. The heater assembly according to claim 1 , wherein the functional layer is thermally sprayed onto the heater substrate.

4. The heater assembly according to claim 1 , wherein the application substrate defines a metal body having a ceramic top surface.

5. The heater assembly according to claim 1 , wherein the application substrate and the heater substrate form a composite substrate with at least two substrates.

6. The heater assembly according to claim 2 , wherein a silver brazing material is used.

7. A heater assembly for use in semiconductor processing comprising:

an application substrate;

a bonding layer;

a heater substrate secured to the application substrate by the bonding layer and by a thermal bonding process;

a bond coat layer disposed onto the heater substrate by a layered process; and

a layered heater comprising a first dielectric layer disposed over the bond coat layer, a resistive heating layer disposed over the first dielectric layer, and a second dielectric layer disposed over the resistive heating layer,

wherein the heater substrate defines a material having a coefficient of thermal expansion that is matched to a coefficient of thermal expansion of the functional layer.

8. The heater assembly according to claim 7 further comprising a topcoat layer disposed over the second dielectric layer.

9. The heater assembly according to claim 7 , wherein each of the layers are applied by a thermal spray process.

10. The heater assembly according to claim 7 , wherein a circuit pattern is formed in the resistive heating layer by a laser removal process.

11. The heater assembly according to claim 7 , wherein the resistive heating layer functions as both a heater and a temperature sensor.

12. The heater assembly according to claim 5 , wherein the composite substrate further comprises more than two substrates such that there is a gradual transition over the composite substrate in terms of coefficient of thermal expansion.

13. The heater assembly according to claim 8 wherein a thickness of the topcoat is non-uniform, such that a predetermined level of surface flatness is achieved.

14. A heater assembly for use in semiconductor processing comprising:

an application substrate;

a bonding layer;

a heater substrate secured to the application substrate by the bonding layer and by a thermal bonding process;

a bond coat layer disposed onto the heater substrate by a layered process;

a first dielectric layer disposed over the bond coat layer;

a resistive heating layer disposed over the first dielectric layer, the resistive heating layer functioning as both a heater and a temperature sensor; and

a second dielectric layer disposed over the resistive heating layer;

wherein the heater substrate defines a material having a coefficient of thermal expansion that is matched to a coefficient of thermal expansion of at least one of the first dielectric layer and a coefficient of thermal expansion of the resistive heating layer.

15. The heater assembly according to claim 14 , wherein the functional layer is thermally sprayed onto the heater substrate.

16. The heater assembly according to claim 14 , wherein the application substrate defines a metal body having a ceramic top surface.

17. The heater assembly according to claim 14 , wherein the first dielectric layer is an alumina material, the heater substrate is a molybdenum material, and the application substrate is an austenitic stainless steel material.

18. The heater assembly according to claim 14 , wherein the application substrate and the heater substrate form a composite substrate with at least two substrates.

19. The heater assembly according to claim 14 , wherein each of the layers are applied by a thermal spray process.

20. The heater assembly according to claim 14 further comprising a topcoat layer disposed over the second dielectric layer.

21. The heater assembly according to claim 18 , wherein the composite substrate further comprises more than two substrates such that there is a gradual transition over the composite substrate in terms of coefficient of thermal expansion.

22. A heated electrostatic chuck having a chuck top comprising:

an application substrate secured to the chuck top;

a heater substrate secured to the application substrate by a thermal bonding process;

a bond coat layer disposed onto the heater substrate by a layered process;

a first dielectric layer disposed over the bond coat layer;

a resistive heating layer disposed over the first dielectric layer, the resistive heating layer functioning as both a heater and a temperature sensor;

a second dielectric layer disposed over the resistive heating layer; and

a top coat layer disposed over the second dielectric layer;

wherein the heater substrate defines a material having a coefficient of thermal expansion that is matched to a coefficient of thermal expansion of at least one of the first dielectric layer and a coefficient of thermal expansion of the resistive heating layer.