The invention relates to temperature control of semiconductor wafers. More particularly, the invention relates to systems and methods for controlling the temperature of a semiconductor wafer held by an electrostatic chuck such as during integrated circuit fabrication.
In semiconductor related production processes, electrostatic chucks are conventionally employed for holding work objects, such as a semiconductor wafers, in a reaction process chamber. A high level of accuracy is required by semiconductor processing apparatuses, such as apparatuses for forming thin films on semiconductor wafers by Physical Vapor Deposition (PVD), Chemical Vapor Deposition (CVD), sputtering and the like, and dry etching apparatuses for microprocessing wafers. Generally, an electrostatic chuck attracts and holds a semiconductor wafer by electrostatic attractive force.
Conventional electrostatic chucks, however, are intended to be used in an environment with a stable temperature thereby meeting desirable critical dimension (CD) uniformity during fabrication processes. Temperature control of the wafer is therefore important when being processed or heated in high temperature environments.
In U.S. Pat. No. 4,645,218, Mayer et al. disclosed an electrostatic chuck preventing damage to the wafers due to high heat. In
As shown in
Systems and methods for temperature control of semiconductor wafers are provided. An exemplary embodiment of semiconductor wafer is held by an electrostatic chuck. An exemplary embodiment of system includes a cooling apparatus connected to the electrostatic chuck. The cooling apparatus comprises an inlet, an outlet, a porous flow layer, a porous contact layer contacting the electrostatic chuck, and a porous heat exchange layer disposed between the flow layer and the contact layer. The inlet communicates with the flow layer, and the outlet communicates with the contact layer. The fluid medium is introduced into the flow layer from the inlet and sequentially flows through the heat exchange layer and the contact layer. The fluid medium is discharged from the contact layer through the outlet, thereby exchanging heat from the semiconductor wafer.
An exemplary embodiment of method for temperature control of a semiconductor wafer held by an electrostatic chuck comprises the steps of providing a porous contact layer connecting the electrostatic chuck, providing a porous flow layer connecting the contact layer, providing a porous heat exchange layer between the flow layer and the contact layer, and inducing a fluid medium into the flow layer to drive the fluid medium sequentially through the flow layer, heat exchange layer and the contact layer.
a is a top view of the flow layer of
b is a top view of the heat exchange layer of
c is a top view of the contact layer of
d is an enlarged view of portion P in
a is a top view of the flow layer 3. The flow layer 3 may be fine tube, porous, silk porous pillar or meshed for example, whereby coolant injected from the manifold holes 6 spreads uniformly and fills the interface between the flow layer 3 and the heat exchange layer 4. The flow layer 3 is provided to support the heat exchange layer 4 and facilitates isothermal uniformity.
Referring next to
Referring to
During various integrated circuit fabrication processes, especially for shallow trench isolation (STI) and polysilicon processes with plasma or non-plasma reactors, such as in Physical Vapor Deposition (PVD) and Chemical Vapor Deposition (CVD) processes, some embodiments of the electrostatic chuck (ESC) cooling system can be used to efficiently provide planar temperature control of the wafer. Potentially, this can improve the stability and isothermal uniformity of the wafer. Thus, manpower and hardware costs for temperature control during fabrication processes may potentially be reduced.
While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
The application claims priority from “Isothermal Planar ESC Cooling Design System”, U.S. Provisional Application No. 60/592,534, filed Jul. 30, 2004.
Number | Date | Country | |
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60592534 | Jul 2004 | US |