The present invention relates generally to semiconductor process tools, and more particularly, to methods and systems for drawing gases away from a process chamber in a semiconductor process tool.
Semiconductor process tools typically include a process chamber formed above a semiconductor wafer support. The processing of the semiconductor wafer (e.g., plasma processing, etching, cleaning, deposition, or any other suitable semiconductor manufacturing process) is conducted within the process chamber.
A gas injection port 110 is included in the process chamber 101. The gas injection port 110 is coupled to one or more process gas sources (not shown) and provides an inlet port for injecting the necessary process gases 111 into the process chamber 101 as may be needed for the desired processing.
The process gases 111 react with the top surface of the semiconductor wafer (not shown) or other substrate for processing in the processing chamber 101 to produce processing byproducts 112. The processing byproducts 112 are then removed from the processing chamber 101 through a gas pump down system 120. An inlet 122 to the gas pump down system 120 is typically located below the plane 118 of the surface of the semiconductor wafer support 102. Thus drawing the processing byproducts 112 downward and off the perimeter of the semiconductor wafer support 102.
The inlet 122 to the gas pump down system 120 is typically located approximately central to the processing chamber 101 and underneath the semiconductor wafer support 102. Centrally locating the inlet 122 to the gas pump down system 120 in the bottom 105 of the processing chamber 101 provides a generally even distribution of a draw on the processing byproducts 112 from every location around the perimeter of the semiconductor wafer support 102. This even distribution of the draw on the processing byproducts 112 is referred to as an azimuthally even distribution. The azimuthally even distribution of the draw helps ensure an azimuthally even processing of the surface of the semiconductor wafer being processed. Asymmetries can also be caused by restrictions of the flow of the process gases proximate to the perimeter of the semiconductor wafer support 102 such as may be caused by adjacent structures and the interior shape of the processing chamber 101.
Unfortunately some arrangements of the process chamber 101 and the semiconductor wafer support 102 may not allow a centrally located inlet 122 to the gas pump down system 120 or even alloy the inlet to be located in the bottom of the process chamber. A non-centrally located inlet to the gas pump down system 120 causes a non-uniform draw and corresponding nonuniform distribution of the process gases 111 and the processing byproducts 112. Typically the process gases 111 and the processing byproducts 112 become concentrated near the non-centrally located vacuum inlet. As a result, the surface of the semiconductor wafer being processed is non-uniformly processed such that some portions of the surface are processed more or less than other portions of the surface.
What is needed is a system and method for producing an azimuthally evenly distributed draw on the byproducts around the perimeter of the semiconductor wafer support from a non-centrally located inlet to the gas pump down system.
Broadly speaking, the present invention fills these needs by is a system and method for producing an azimuthally evenly distributed draw on the byproducts around the perimeter of the semiconductor wafer support from a non-centrally located inlet to the gas pump down system. The present invention also includes systems and methods of pumping out the process gases from above the wafer plane. It should be appreciated that the present invention can be implemented in numerous ways, including as a process, an apparatus, a system, computer readable media, or a device. Several inventive embodiments of the present invention are described below.
One embodiment provides a system for processing a substrate in a processing chamber and providing an azimuthally evenly distributed draw on the processing byproducts using a gas pump down source coupled to the processing chamber above the plane of a substrate support within the processing chamber. The process chamber can include an annular plenum disposed between the support surface plane and the chamber top, the plenum including at least one vacuum inlet port coupled to the gas pump down source and a continuous inlet gap proximate to a perimeter of the substrate support, the continuous inlet gap having an inlet gas flow resistance of between about twice and about twenty times an outlet gas flow resistance the at least one vacuum inlet port.
The at least one vacuum inlet port can include at two or more vacuum inlet ports. The two or more vacuum inlet ports can be unevenly or substantially evenly distributed around the perimeter of the annular plenum.
The annular plenum can be included in the chamber top and/or the chamber sides. The annular plenum can be formed by an extension extending from the chamber top and toward the chamber sides and the continuous inlet gap can be formed between the extension and the chamber sides. The annular plenum can also be disposed between the chamber top and a plane of the substrate support.
Another embodiment provides a method of flowing gases through a processing chamber including inputting a gas flow into the processing chamber, distributing the gas flow in a substantially even azimuthal distribution from the center portion of the top of the processing chamber to a continuous inlet gap disposed near a perimeter of the processing chamber wherein the continuous inlet gap has a gas flow resistance of at least twice a gas flow resistance of at least one vacuum inlet port disposed in the top of the processing chamber. The continuous inlet gap is disposed between a substrate support plane and the processing chamber top. The continuous inlet gap is fluidly coupled to an annular plenum, the annular plenum including the at least one vacuum inlet port, the at least one vacuum inlet port being coupled to a gas pump down source capable of drawing the gas flow out of the processing chamber, through the continuous inlet gap, into the annular plenum and out through the at least one vacuum inlet port.
Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.
The present invention will be readily understood by the following detailed description in conjunction with the accompanying drawings.
Several exemplary embodiments for is systems and methods for producing an azimuthally evenly distributed draw on the byproducts around the perimeter of the semiconductor wafer support from a non-centrally located inlet to the gas pump down system will now be described. Systems and methods of pumping out the process gases from above the wafer plane will also be described. It will be apparent to those skilled in the art that the present invention may be practiced without some or all of the specific details set forth herein.
An integrated strip allows the etch and strip process tools to process semiconductor wafers in an integrated fashion without removing the semiconductor wafers from the process tools instead of processing in a “batch mode.” As a result, the integrated strip provides for increased efficiency and semiconductor wafer throughput.
The integrated strip is possible as the etch 183 and strip 184 processing tools are coupled to the cluster chamber 181. However, space constraints on the cluster chamber 181 do not allow gas pumping from underneath the semiconductor wafer support, leading to non-uniform azimuthal flow distribution and the corresponding azmuthal non-uniformity of the processing of the semiconductor wafer as described in more detail below.
Adding multiple inlets to the gas pump down system results in multiple locations of concentrated flow byproducts resulting in multiple uneven distributions of the draw on the byproducts around the perimeter of the semiconductor wafer support. Corresponding multiple azimuthal process nonuniformities are caused by the corresponding uneven processing of the semiconductor wafer.
One implementation provides for a system and method of top pumping through an annular, 360 degree inlet that can be located above, even with or below a semiconductor wafer support plane. The annular, 360 degree inlet forces gases to be drawn away from the perimeter of the semiconductor wafer support, in an azimuthally evenly distributed flow. The annular, 360 degree inlet can include an annular plenum having a relatively narrow, annular inlet gap proximate to an outer perimeter of the semiconductor wafer support. The annular plenum is coupled to one or more top pumping inlet ports to the gas pump down system. The narrow annular inlet gap creates sufficient flow resistance to mask the flow concentration effects of one or more top pumping inlet ports, as shown in
The annular plenum 224 can be formed as a space within the chamber top as shown in
The inlet gap 220 provides a substantially uniform draw azimuthally around the perimeter of the inlet gap to substantially eliminate any localized flow concentrations near the vacuum inlet ports 222. The inlet gap 220 includes a flow resistance to the azimuthally evenly distributed flow 215 greater than a flow resistance at any one of the inlet ports 222. By way of example, the inlet gap 220 can have a flow resistance of about twice the flow resistance at any one of the vacuum inlet ports 222. Alternatively, the inlet gap 220 can have a flow resistance of between about five and about ten times the flow resistance at any one of the vacuum inlet ports 222. As the flow resistance provided by the vacuum inlet gap 220 increases, the flow 215 becomes increasingly azimuthally evenly distributed such that the gas flow varies between about 0.0 meters per second and about 0.6 meters per second between locations around the perimeter of the inlet gap 220.
However, as the flow resistance provided by the inlet gap 220 increases the gas flow 215 velocity at the entry to the inlet gap also increases. As the flow resistance of the inlet gap 220 is increasing, the minimum pressure inside the processing chamber is also increasing also for a given gas flow. This increased minimum pressure can result in undesirable process variations and also results in increased process gas consumption and corresponding increase in operating costs. As the gas flow 215 velocity increases then turbulence can also increase. The turbulence can then cause disruptions in the azimuthally even distribution. By way of example, the flow resistance provided by the inlet gap 220 is selected to increase the gas flow 215 velocity to a velocity that is less than or about equal to the gas flow velocity of the process gases 111 at the injection port 110. It should be understood that in some process chamber configurations and processes the may allow or tolerate higher gas flow 215 velocities at the inlet gap 220. Alternatively, some process chamber configurations and processes the may not allow or tolerate higher gas flow 215 velocities at the inlet gap 220. Thus the precise gas flow 215 velocity at the inlet gap 220 is dependent on the selected process conducted within the process chamber and also dependent on the configuration (e.g., shape and arrangement) of the various components within the process chamber.
The three vacuum inlet ports 222 can be substantially evenly distributed around the perimeter of the annular plenum 224 (e.g., angles β, θ and α are equal at about 120 degrees each). Alternatively, the three vacuum inlet ports 222 can be unevenly distributed around the perimeter of the annular plenum 224. For example, angle β can be about 90 degrees while angle θ and α can be about 120 degrees and 150 degrees, respectively. These values of the angles β, θ and α are merely exemplary and it should be understood that the angles β, θ and α can be any suitable dimension as may be required by the structure and space limitations of the chamber system 200.
A load port 240 is also included in the second alternative processing chamber 201″. A load port 240 is also provided in each of the above processing chambers 201, 201′. The load port 240 provides access to load (i.e., insert) and unload (i.e., remove) the semiconductor wafer, or other suitable substrate, to be processed in the processing chamber 201, 201′, 201″. The location of the load port 240 on the processing chambers 201, 201′, 201″ may also prevent the vacuum inlet ports 222, 222′ from being evenly distributed around the perimeter of the annular plenum 224. Thus, in at least one embodiment, the load port may generate the need for the masking effects of the annular plenum 224 and the inlet gap 220.
It should be understood that the vacuum inlet ports 222′ and 222″ may be sized differently than the vacuum inlet ports 222. By way of example, vacuum inlet ports 222′ may be larger than vacuum inlet ports 222 so that the two vacuum inlet ports 222′ can draw the same flow rate while having the same flow restriction as the three vacuum inlet ports 222. Similarly, the single vacuum inlet port 222″ may be sized larger than the two vacuum inlet ports 222′ so as to provide the same flow rate while having the same flow restriction as the three vacuum inlet ports 222. It should also be understood that any suitable cross-sectional shape (round, triangular, oval, rectangular, etc.) of the vacuum inlet ports 222 can be utilized.
While embodiments having one, two and three vacuum inlet ports are described herein, it should be understood that more than three vacuum inlet ports could also be included in the processing chamber 201. It should also be noted that each of the multiple vacuum inlet ports 222, 222′ may be sized differently than remaining vacuum inlet ports so as to select the flow restriction in each of the vacuum inlet ports as may be required by the structure and space limitations of the process chamber system 200.
By way of example, the gas flow 320 velocity in region 304 is slower than the gas flow velocity in region 302. Similarly, the gas flow velocity drops further in each successive annular regions 304-312.
The outermost annular region 314 is proximate to the inlet gap 220 (not shown). When the gas flow 320 arrives at the outermost annular region 314, the gas flow velocity drastically increases as a result of the draw from the gas pump down source 230 as distributed by the annular plenum 224 and the inlet gap 220.
Referring now to
The gas flow velocity can further decrease as the gas flows from the annular plenum 224 and into the vacuum inlet ports 222 to further aid in masking the location of the vacuum inlet ports from the process chamber. As described elsewhere in more detail, the gas flow velocity in the vacuum inlet ports 222 is about one half or less than the gas flow velocity in the inlet gap 220. The lower gas flow velocity in the vacuum inlet ports 222 masks the location of the vacuum inlet ports from the process chamber which allows the annular plenum 224 and the inlet gap 220 to apply an azimuthally even draw on the gases in the processing chamber near the inner wall of the processing chamber.
The relative volumes of the annular plenum 224 and into the vacuum inlet ports 222 determine the gas flow velocity. If the volume of the vacuum inlet ports 222 is greater than the volume of the annular plenum 224, then the gas flow velocity will decrease. Alternatively, if the volume of the vacuum inlet ports 222 is less than the volume of the annular plenum 224, then the gas flow velocity will increase. If the volume of the vacuum inlet ports 222 is about equal to the volume of the annular plenum 224, then the gas flow velocity will remain substantially constant.
The annular plenum 624 and the inlet gap 620 can be formed from a metal (e.g., aluminum or steel or alloys thereof, etc.). Alternatively, the annular plenum 624 and the inlet gap 620 can be formed from a suitable ceramic material (e.g., quartz, glass, alumina, etc.). Forming the annular plenum 624 separately from the sides 104 and top 103 of the process chamber 601 allows a different material and to be utilized in the annular plenum 624 than in the other portions of the process chamber and other structures included within the process chamber.
In an operation 705, one or more substrates are placed in the processing chamber for processing and the process chamber is closed for processing. Referring to the cluster type tools in
In an operation 710, one or more process gases are injected into the processing chamber and the processing of the substrates begins. The processing of the substrates may also include applying the required biasing currents and RF to one or more electrodes (e.g., top inner surface 103 and/or substrate support 102) within the processing chamber.
In an operation 715, a gas pump down source is applied to an annular plenum 224, 524, 624 though one or more vacuum inlet ports 222, 222′, 222″. The annular plenum substantially evenly distributes the draw of the one or more vacuum inlet ports 222, 222′, 222″ to the inlet gap 220, 520, 620 near the perimeter of the substrate support 102.
In an operation 720, the inlet gap 220, 520, 620 draws processing byproducts into the annular plenum in an azimuthally evenly distributed draw off the perimeter of the surface being processed. The annular gap provides a flow resistance sufficient to mask the locations of the one or more vacuum inlet ports 222, 222′, 222″.
In an operation 725, the processing of the substrate surface is completed and the process gas flows and biasing current and RF can be terminated. The substrate can then be removed from the processing chamber, in an operation 730, and the method operations can end.
One or more process gas sources 802 are also coupled to the inlet port 110 of the processing chamber. The process gas sources 802 also include any necessary flow controllers, flow meters, valves, manifolds, mixers and pressure controllers 804 as may be needed to deliver the process gases to the processing chamber.
A controller 808 is also included in the processing chamber system 800. The controller 808 is coupled to control inputs and instrumentation outputs 806, 804 on each of the process gas sources 802, the processing chamber and the gas pump down system 230. The controller 808 includes an electronic control unit 809 for monitoring and controlling the processing chamber system 800. The controller 808 also includes one or more recipes in an electronically executable form for controlling and monitoring the operations of the processing chamber system 800.
The computer system 900 includes a central processing unit 904, which is coupled through a bus 910 to memory 928, mass storage 914, and Input/Output (I/O) interface 920. Mass storage 914 represents a persistent data storage device such as a hard drive or a USB drive, which may be local or remote. Network interface 930 provides connections via one or more networks such as the Internet 932, allowing communications (wired or wireless) with other devices. It should be appreciated that CPU 904 may be embodied in a general-purpose processor, a special purpose processor, or a specially programmed logic device.
Input/Output (I/O) interface 920 provides communication with different peripherals and is connected with CPU 904, memory 928, and mass storage 914, through the bus 910. Sample peripherals include display 918, keyboard 922, mouse 924, removable media device 934, etc.
Display 918 is configured to display the user interfaces described herein. Keyboard 922, mouse 924, removable media device 934, and other peripherals are coupled to I/O interface 920 in order to exchange information with CPU 904. It should be appreciated that data to and from external devices may be communicated through I/O interface 920. Embodiments of the invention can also be practiced in distributed computing environments where tasks are performed by remote processing devices that are linked through a wired or a wireless network.
Embodiments of the present invention can be fabricated as computer readable code on a non-transitory computer readable storage medium. The non-transitory computer readable storage medium holds data which can be read by a computer system. Examples of the non-transitory computer readable storage medium include permanent storage 908, network attached storage (NAS), read-only memory or random-access memory in memory module 928, Compact Discs (CD), Blu-ray™ discs, flash drives, hard drives, magnetic tapes, and other data storage devices. The non-transitory computer readable storage medium may be distributed over a network coupled computer system so that the computer readable code is stored and executed in a distributed fashion.
Some, or all operations of the method presented herein are executed through a processor, such as CPU 904 of
In addition, at least one operation of some methods performs physical manipulation of physical quantities, and some of the operations described herein are useful machine operations. Embodiments presented herein recite a device or apparatus. The apparatus may be specially constructed for the required purpose or may be a general purpose computer. The apparatus includes a processor capable of executing the program instructions of the computer programs presented herein.
Although the foregoing invention has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.