Patent Application
20140120735
The present application relates generally to semiconductor devices and includes methods and apparatus for improving uniformity of deposition and/or concentration of material on a semiconductor wafer.
An important capability for manufacturing reliable integrated circuits is to uniformly treat a semiconductor wafer. If, in a process step, a treatment is applied unevenly to the wafer, a difference in thickness of deposited material or concentration (e.g., Boron, Phosphorus, Nitrogen, or another dopant concentration) may occur across the wafer. These differences may cause device defects or require additional process steps to correct. For example, if a deposition is not uniform, a longer or more aggressive chemical mechanical planarization (CMP) step may be required. As another example, if a certain Boron, Phosphorus, Nitrogen, or other dopant concentration is specified, non-uniform concentrations may result in inoperable or otherwise unacceptable devices at some locations on the wafer resulting in lower production yield and higher device cost. With the reduction in size of semiconductor devices, increase in size of wafers and desire for higher production yields, these differences are a significant issue and improved uniformity is desired.
According to one embodiment, a semiconductor processing apparatus includes a process chamber, a pedestal and a showerhead. The pedestal is inside the process chamber and holds a semiconductor wafer. The showerhead supplies process gas to the process chamber. The showerhead has a plurality of controllable outlets that supply one or more process gases to the process chamber.
According to another embodiment, a semiconductor processing apparatus includes a process chamber, a pedestal and a showerhead. The pedestal is inside the process chamber and holds a semiconductor wafer. The showerhead supplies process gas to the process chamber. The pedestal is rotatable while gas flows through the outlets of the showerhead.
According to another embodiment, a semiconductor processing apparatus includes a process chamber, a pedestal and a showerhead. The pedestal is inside the process chamber and holds a semiconductor wafer. The showerhead supplies process gas to the process chamber. The showerhead has a plurality of controllable outlets that supply one or more process gases to the process chamber. The pedestal is rotatable while gas flows through the outlets of the showerhead.
According to another embodiment, a method for processing a semiconductor wafer includes: providing a semiconductor wafer on a pedestal; supplying a process gas to the semiconductor wafer to perform a process step; and controlling the supply of the process gas to the semiconductor wafer to improve uniformity of the process step.
Referring to
The pedestal 14 is fixed in the process chamber 10 during a processing step and holds the semiconductor wafer 20 in a fixed location during the processing step. The pedestal 14 may be movable in the sense that sometimes moves the wafer 20 to the processing chamber 10, but it static and does not move during a semiconductor process.
It will be appreciated that some embodiments may include one of the multi-showerhead 112 and the spin pedestal 114. That is, some embodiments may include the multi-showerhead 112, some embodiments may include the spin pedestal 114, and some embodiments may include both the multi-showerhead 112 and the spin pedestal 114.
The number of outlets and control of the outlets 122 may be provided in a number of ways. The outlets may be controlled individually or they may be controlled in groups. For example, as shown in
The use of concentric zones 130a, 130b and 130c allows for adjustment of the distribution of process gas between an edge and a center of a wafer while still maintaining a relativly simple and cost effective implementation. In combination with the rotating pedestal, which improves uniformity at a given radial distance, the concentric circle arrangement, which improves uniformity at different radiuses, synergistically improves uniformity across the entire wafer.
Each of the zones 130 may be individually supplied with process gases, such as TEOS, TEB, and TEPO, from a gas box 132 via lines 134a, 134b, 134c, 136a, 136b, 136c, 138a, 138b and 138c. Lines 134 supply a first process gas to zones 130, lines 136 supply a second process gas to zones 130 and lines 138 supply a third process gas to zones 130. In this manner, each of the process gases can be individually controlled within each of zones 130. In some embodiments, the processes gases may be supplied as a mixed gas to the zones 130 to reduce the number of control valves needed.
Referring to
Referring to
The controller 150 is connected to a motor 153 to control the rotation of the spin pedestal 114. The controller 150 is connected to supply valves 152a, 152b and 152c to control the supply of gas from gas supplies 154a, 154b and 154c respectively. The controller 150 is connected to supply valves 156a, 156b, and 156c to control the supply of gas to outlets 158a, 158b and 158c of multi-showerhead 112 respectively. Each of supply valves 154a, 154b and 154c includes a valve that individually controls one supply gas. That is, if there are three gas supplies and three outlets of the multi-showerhead, the supply valves 154a, 154b and 158c include a total of 9 valves. Independent control of each supply gas at each region allows for finer control of the process. For example, it may be measured that a certain region of the wafer has a non-optimal concentration of an element related to one of the supply gases. Allowing the manipulation of that supply gas locally to a region of the wafer provides for greater control of the process. The valves 152, 154, 156 and 158 may provide varied gas flow or they may provide discrete on/off control.
Referring to
As compared to the processing apparatus shown in
It will be appreciated that the embodiments shown in
Referring now to
At step S5, the processing step is adjusted. For example, gas flow to zones of the multi-showerhead over thick areas may be reduced, gas flow to zones of the multi-showerhead over thin areas may be increased, and the rotation of the spin pedestal may be increased or decreased. The process then continues to step S1.
At step S6, the calibration (i.e., the gas flow to each of the zones of the multi-showerhead, rotation of the spin pedestal, etc) is stored and the process is completed.
With the calibration information stored, it can be referenced to improve the uniformity of processes performed by the processing apparatus.
Exemplary benefits of the above described semiconductor processing device include improved uniformity of concentration or thickness of a treatment applied to a semiconductor wafer. The described semiconductor processing device may be used for the deposition of oxides and other films (SiN, SiO2, etc) as well as for controlling the concentration of Boron (B%), Phosphorus (P%), Nitrogen (N%) and other dopants in a processing step.
While various embodiments in accordance with the disclosed principles have been described above, it should be understood that they have been presented by way of example only, and are not limiting. Thus, the breadth and scope of the invention(s) should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the claims and their equivalents issuing from this disclosure. Furthermore, the above advantages and features are provided in described embodiments, but shall not limit the application of such issued claims to processes and structures accomplishing any or all of the above advantages.
Additionally, the section headings herein are provided for consistency with the suggestions under 37 C.F.R. 1.77 or otherwise to provide organizational cues. These headings shall not limit or characterize the invention(s) set out in any claims that may issue from this disclosure. Specifically and by way of example, a description of a technology in the “Background” is not to be construed as an admission that technology is prior art to any invention(s) in this disclosure. Neither is the “Summary” to be considered as a characterization of the invention(s) set forth in issued claims. Furthermore, any reference in this disclosure to “invention” in the singular should not be used to argue that there is only a single point of novelty in this disclosure. Multiple inventions may be set forth according to the limitations of the multiple claims issuing from this disclosure, and such claims accordingly define the invention(s), and their equivalents, that are protected thereby. In all instances, the scope of such claims shall be considered on their own merits in light of this disclosure, but should not be constrained by the headings set forth herein.
