Patent Application
20150017805
Semiconductor devices are used in a wide range of consumer electronics, computers, communication equipment, and various other products. They are made from silicon, or other semiconductor materials, that are often in the form of disc-shaped wafers. The wafers undergo many manufacturing processes to form the microelectronic circuits. During various manufacturing steps, the wafers are processed using fluid chemicals (e.g., acids, caustics, etchants, photoresists, plating solutions, purified water, etc.) as well as gaseous chemicals. They are also rinsed and dried to remove contaminants which can cause defects in the end product devices or otherwise interfere with subsequent process steps.
As greater emphasis is placed on the scaling down the size of microelectronics circuits, new processes must be developed and the accuracy of existing processes must be honed. However, current single wafer processing apparatus increasingly do not meet these demands. The designs of such single wafer processing apparatus make it difficult to improve the accuracy of the processes they perform. Further, such single wafer processing apparatus often use an excessive amount of processing chemistry beyond that needed to execute their processing operations. Wasted chemistry is both uneconomical and, if caustic, a hazard to the environment.
An apparatus for processing a wafer is disclosed that includes a wafer support and a processing base. The wafer support is configured to support a wafer in a processing position, and to rotate the wafer about a first substantially vertical axis while in the processing position. The processing base includes a shallow dish configured to receive processing chemistry. The wafer support places the wafer in contact with the processing chemistry while in the processing position. The shallow dish is rotatable about a second substantially vertical axis when the wafer support is in the processing position. The rotation of the wafer is independent of the rotation of the shallow dish. Further, the processing base may include a heating element, such as an infrared heating element, that is disposed to locally elevate the temperature of of the shallow dish and chemistry contained in it.
The features, functions, and advantages that are discussed below can be achieved independently in various embodiments or may be combined in yet other embodiments further details of which can be determined with reference to the following description and drawings.
The wafer head 20 may also be driven along axis 45 by a still further motor 50. In this example, motor 50 is configured to drive the wafer head 20 and corresponding wafer support 35 between the elevated position shown in
The processing base 25 includes an outer shell assembly 55 that surrounds a dish assembly 60. The outer shell assembly 55 includes passages through which processing chemistry may be accepted from dish assembly 60 and recirculated and/or removed from the processing base 25. The dish assembly 60 includes a shallow dish 65 configured for rotation by motor 70 about a substantially vertical axis 75. In the embodiment of
In certain processes, the temperature of the chemistry in the shallow dish 65 may need to be elevated. Heating may occur in a pre-heating operation exterior to the shallow dish 65. In the embodiment of the dish assembly 60 shown in
A control system 85 may govern the operation of the apparatus 10. In one example, the control system 85 includes a drive/valve controller 90, a temperature controller 93, and a chemistry controller 95. The drive/valve controller 90 may direct operation of the various motors of the apparatus 10. These operations may include: 1) elevating the wafer head 20 along axis 45 and rotating it to a wafer face-up orientation about axis 27 to receive the wafer to be processed on the wafer support 35; and 2) rotating the wafer head about axis 27 to a wafer face-down orientation and driving it along axis 45 to place the wafer in the processing position with respect to the processing base 25. The drive/valve controller 90 may also direct the valves of the apparatus 10 to various states during processing to govern fluid flow. The temperature controller 93 is configured to operate the heating element 80 and govern the temperature of the chemistry in the shallow dish 65 in response to a temperature sensor proximate the heating element 80.
The chemistry controller 95 governs the supply of various processing chemistries to the processing base 25 in cooperation with the drive/valve controller 90. The chemistry controller 95 may operate to: 1) regulate the content of the mixture of the processing chemistry; 2) monitor properties of the processing chemistry; 3) add constituents to the processing chemistry; 4) regenerate used chemistry for further use; and/or 5) regulate recirculation, waste treatment, and/or disposal of the processing chemistry.
The shallow dish 65 is rotated by motor 70 while the wafer 15 is in contact with the processing chemistry. The rotation imparted to the shallow dish 65 by motor 70 is independent of the rotation imparted to the wafer 15 and wafer support 35 by motor 30. As such, the rotation of the shallow dish 65 may be at a different rate and/or direction than the rotation of the wafer 15. The relative rotation of the wafer 15 and the shallow dish 65 may be adjusted to provide even processing of the wafer for the particular type of processing operation for which apparatus 10 is designed.
A rotary union 105 is configured to receive the processing chemistry from a chemistry supply system (not shown). The rotary union 105 directs a flow of the processing fluid through a central opening of the shallow dish 65 and into the basin 100. This initial flow is shown by flow lines 110. Rotation of the shallow dish 65 by the motor 70 causes the processing chemistry to flow across the face of the wafer 15 toward its periphery under the effect of centrifugal force. At the periphery, the processing chemistry flows over a lip 115 and exits the shallow dish 65 as shown by flow lines 120. From there, the chemistry may be recirculated or handled in the manners described above with respect to the chemistry controller 95. Operation of the rotary union 105 may be governed by one or more elements of the control system 85.
The heating element 80 is disposed proximate an underside of the shallow dish 65. Both the heating element 80 and the shallow dish 65 may be disc shaped. In the illustrated example, the heating element 80 is substantially coextensive with the underside of the shallow dish 65 in that it has an upper surface having a diameter approximately the same as the diameter of the underside of the shallow dish 65. However, different geometric configurations of the heating element 80 with respect to the shallow dish 65 may likewise be used to provide the localized heating of the shallow dish 65 depending on system design requirements.
The heating element 80 may be an infrared heating element or the like, and the shallow dish 65 may be formed from a thermally conductive material, such as quartz. The heating element may be arranged so it is: 1) immediately adjacent the backside of the shallow dish 65; 2) separated from the backside of the shallow dish 65 by a fluid, such as air, in interstitial region 125; 3) separated from the backside of the shallow dish 65 by a fluid in interstitial region, where the fluid is has a high thermal conductance. Further, the heating element 80 may be configured so it is stationary with respect to the shallow dish 65, or co-rotates with the shallow dish 65. Heating element 80 may be thermally isolated from the motor 70 and other components of the dish assembly 60 by placing a thermal insulator in region 130. Further thermal isolation may be obtained by placing a thermal insulator around a periphery of the heating element 80.
Heating element 80 is disposed in a heating chamber 175. Here, the heating chamber 175 is defined by a bottom insulating layer 180 and a side insulating layer 185. The top of the heating chamber 175 is defined by the underside of the shallow dish 65 so the heating element 80 may locally heat the shallow dish 65 and the processing chemistry in the shallow dish 65. Heating of the shallow dish 65 may be direct or indirect depending on whether the heating element 80 is in direct or indirect contact with the underside of the shallow dish 65. The bottom insulating layer 180 may be disc shaped and dimensioned to be coextensive or extend beyond the periphery of the heating element 80. Further, the side insulating layer 185 may extend about the periphery of the heating element and has a height below, level, or higher than the upper surface of the heating element 80.
The processing base 25 includes a body portion 190 having a main fluid channel 195. The main fluid channel 195 that may extend about the periphery of the processing base 25 to collect the processing chemistry overflowing lip 125. There are also two fluid catches disposed continuously or intermittently about the inner periphery of the processing base 25. A first fluid catch 200 is disposed at a first elevation of processing base 25, while a second fluid catch 205 is disposed at a second elevation.
Once the residual chemistry is spun off at the first intermediate processing position, the wafer head 25 may further elevate the wafer 15 to the second intermediate processing position shown in
The wafer 15 may also be subject to additional processing operations in the method of
