Patent Application
20070020115
The invention relates to an integrated pump apparatus for use in semiconductor processing. The apparatus may include a turbomolecular pump and a dry pump positioned no more than about 20 centimeters away from each other. The turbomolecular pump and dry pump may share at least one of a common housing and a common controller. The apparatus may also include at least one of an abatement device and a cryogenic water pump.
Semiconductor wafers are used to form a number of different types of devices. For example, wafers, or portions of wafers, may be used to form memory devices, microprocessor unit devices, or combinations of the two devices. The devices may be very small, (e.g., on the order of only one Micron), and thus these devices are often manufactured in large batches. In some instances, a single wafer may have hundreds of devices manufactured on it.
In order to manufacture a device on a wafer, a number of discrete steps are performed. Although the number of steps may vary greatly depending on the type and complexity of the device, a typical manufacturing process may include anywhere between 100 and 300 individual steps between the initial step of providing an initial substrate and the finals step of extracting individual devices from the wafer and installing them in personal computers, telephones, mobile phones, or other electronic equipment.
Some of the steps in semiconductor wafer processing may include etching away selected material, depositing selected materials, and performing selective ion implantation in the silicon wafer. Many of these steps are performed by tools especially designed for the particular step, but several steps may also be performed by a single tool. Because these steps may be performed in a variety of locations, the wafer may often be moved. For example, the wafer may be placed in and taken out of ion implanter tools, transported by cassettes, placed in and taken out of deposition tools, and placed in and taken out of etch tools, etc.
As mentioned above, etching is one form of processing that may be performed on a wafer. The wafer may be etched a number of different times at a number of different levels for a number of different reasons. For example, one type of etching step includes placing a photoresist type material over an area of the wafer. The photoresist on the wafer may be then be exposed to a light source with a specific wavelength and a specific pattern. The exposure of the photoresist to the light source may alter the chemical composition of the exposed area such that the photoresist either “hardens” so that when a chemical is applied the “hardened” photoresist remains, or “softens” so that when a chemical is applied the “softened” photoresist is removed. In either case, a desired photoresist pattern remains on the wafer. Using this remaining photoresist as a mask, chemical substances may be applied to the wafer so as to etch away or remove exposed portions of the wafer. Thus, a desired pattern may be “etched” into the silicon wafer.
The devices and/or patterns that are etched into the wafer often have dimensions that are on the order of one micron. Because the dimensions being dealt with are so small, etching processes are especially susceptible to contaminants. For example, foreign molecules may become lodged in the channels etched into the wafers, and the existence of such flaws may prevent a device or portions of the device from working properly. Accordingly, in order to minimize these flaws, much attention is paid to the method by which the etching is performed, specifically by working to minimize the number of contaminants in the system.
The most common method of controlling the etching is by etching in a vacuum chamber using a plasma. The vacuum chamber is, by definition, kept at a low pressure, for example, between pressures of about 10−3 millibar and about 10−1 millibar. The plasma used to etch the wafers may include the addition of any number of substances, such as fluorocarbons or perflourocarbons, which within the plasma may be broken up into smaller portions, such as fluorine and fluorine radicals. These smaller portions react with the exposed portions of the wafer and “etch away” that portion of the wafer through the formation of volatile reactant by-products. Other substances may be used depending on the substrate to be etched. Performing this procedure under vacuum substantially prevents contaminants from entering the system, as the chemicals present are normally only those specifically introduced into the system and the reduced pressure may moderate the reaction rate as the molecular density may be lower.
In a number of current etching procedures, a large number of reactants are run past the wafer at high speeds, for example, on the order of thousands of liters per second. This runs contrary to the desire to minimize the number of contaminants by keeping the pressure in the vacuum chamber low. What results is a desire to pass etching substances through the vacuum chamber at high speeds, but low pressures, and thus specialized pumps are often desired.
Currently, there are two discrete, completely separate, unintegrated pumps used in conjunction with each other to provide a high flow rate of etching substance at low pressures. The pumps have, among things, separate housings, separate controllers, separate electrical connections, and separate fluid connections, and are located long distances away from one another in different rooms of a wafer processing facility.
In some current configurations, an inlet of a first pump is bolted to the bottom of the vacuum chamber and receives the substances from the vacuum chamber that are flowing at the low pressures. The first pump then gradually increases the pressure of the substance flow from the molecular level (at the inlet) to about the transition level (at the outlet). The substance flow is then sent through a tube or pipe to a second pump which is located in another room, for example, a basement of the wafer processing facility. The second pump is currently located in another room of the wafer processing facility for several reasons, most prominent of which are its size, the amount of noise it generates, and its maintenance. The flow path (e.g. tube) connecting the pumps is typically between 5 and 15 meters in length, with a minimum length of 3 meters and a maximum length of 20 meters. The second pump gradually increases the pressure of the substance flow from about the transition level (at the inlet) to about atmospheric pressure (at the outlet). The second pump then exhausts the substance flow.
There are some drawbacks associated with the current dual pump arrangement. For example, having the second pump in a room separate from the first pump is often an inefficient use of space. In addition, there are efficiency losses associated with flowing the substances through a long tube connecting the pumps. Accordingly, alternative arrangements and/or configurations of multiple pumps are desired.
In the following description, certain aspects and embodiments of the invention will become evident. It should be understood that the invention, in its broadest sense, could be practiced without having one or more features of these aspects and embodiments. It should also be understood that these aspects and embodiments are merely exemplary.
One aspect, as embodied and broadly described herein, may relate to an apparatus for use in semiconductor processing. The apparatus may include a turbomolecular pump and a dry pump, and the turbomolecular pump and the dry pump may be coupled together so as to position the turbomolecular pump and the dry pump no more than about 20 centimeters from one another.
In a further aspect, an apparatus for use in semiconductor processing may include a turbomolecular pump and a dry pump coupled to the turbomolecular pump. The apparatus may include at least one of a common housing associated with both of the pumps and a common controller associated with both of the pumps.
Still another aspect may relate to an apparatus that may include a turbomolecular pump, a dry pump coupled to the turbomolecular pump, and a semiconductor processing tool associated with the turbomolecular pump and the dry pump. The turbomolecular pump, the dry pump, and the semiconductor processing tool may be disposed in a single room of a facility where semiconductors are processed.
Various aspects may include one or more optional features. For example, the turbomolecular pump and the dry pump may be coupled together so as to position the turbomolecular pump and the dry pump no more than about 10 centimeters from one another; the turbomolecular pump and the dry pump may be coupled together so as to position the turbomolecular pump and the dry pump no more than about 0.5 centimeters from one another; the apparatus may include at least one of a common housing associated with both of the pumps and a common controller associated with both of the pumps; the apparatus may include a semiconductor processing tool associated with the turbomolecular pump and the dry pump; the turbomolecular pump, the dry pump, and the semiconductor processing tool may be disposed in a single room of a facility where semiconductors are processed; the boundary between the turbomolecular pump and the dry pump may not be externally discernable; the apparatus may include only one electrical connection configured to provide electrical power input to both of the pumps; the apparatus may include only one fluid connection configured to provide fluid to at least one of the pumps; the apparatus may include only one cooling water connection configured to provide cooling water to at least one of the pumps; the apparatus may include only one nitrogen connection configured to provide nitrogen to at least one of the pumps; the apparatus may include only one clean dry air connection configured to provide clean dry air to at least one of the pumps; the apparatus may include a common controller; the common controller may control both the turbomolecular pump and the dry pump; the apparatus may include a cryogenic water pump; the common controller may be associated with the cryogenic water pump; the common controller may control the turbomolecular pump, the dry pump, and the cryogenic water pump; the apparatus may include an abatement device; the common controller may be associated with the abatement device; and the common controller may control the turbomolecular pump, the dry pump, and the abatement device.
Aside from the structural relationships discussed above, the invention could include a number of other forms such as those described hereafter. It is to be understood that both the foregoing description and the following description are exemplary only.
The accompanying drawings, which are incorporated in and constitute a part of this specification. The drawings illustrate several embodiments of the invention and, together with the description, serve to explain some principles of the invention. In the drawings:
Reference will now be made in detail to some possible embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
The turbomolecular pump 10 may be a pump configured to provide turbomolecular flow of a substance such that molecules of the substance are more likely to collide with at least one interior wall 15 (
Adjacent blades 13 may be spaced from one another by an intervening stator 14. The stators 14 may remain substantially stationary during the pumping process, and may be fixed to an outer cylinder that surrounds the blades 13.
The molecules entering the pump 10 may have a substantially random motion. These molecules may then land on a rotating blade 13 and pick up the blade's 13 velocity such that on leaving the blade 13, the molecule has the velocity of the blade 13 as well as the blade's intrinsic thermal velocity. Thus, compression may be generated by a combination of blades 13 providing a higher transmission probability downwards rather than upwards due to the angle of blades 13 and the relative blade velocity. Stationary stator 14 is also configured such that it generates compression through a combination of the relative gas velocity and the stator 14 providing a higher transmission probability downwards as compared to upwards due to the angle of the stator blade. The stator 14 may have a relative velocity from the reference of the molecule such that equal pumping may be provided by stator 14 and blade 13.
Additional details concerning exemplary configurations of a turbomolecular pump 10 with blades 13 and stators 14, and its various components, are set forth in U.S. Pat. Nos. 6,109,864 and 6,778,969, which are both incorporated herein by reference in their entirety.
Each of the blades 13, intervening stators 14, and/or other portions of the turbomolecular pump 10 may be configured to efficiently move substances at low pressures. Turbomolecular pumps typically operate with inlet pressures between 10−1 millibar to 10−8 millibar and corresponding outlet pressures from 10 millibar to 1 millibar or less depending on flow and the size of the pump downstream. One or more of blades 13 and intervening stators 14 may rotate at relatively high speeds, for example, up to twenty-thousand revolutions-per-minute or more.
The turbomolecular pump 10 may include a molecular drag portion 17. The molecular drag portion 17 may be disposed before and/or after the blades 13 and stators 14. The molecular drag portion 17 may include two co-axial hollow cylinders 18, 19. One or more of the cylinders 18, 19 may have a helical thread 20 provided on the surface facing the other cylinder 18, 19. In operation, one or more of the cylinders 18, 19 may rotate at relatively high speeds, for example, up to twenty-thousand revolutions-per-minute or more. Accordingly, at low pressures the molecules may strike the surface of the rotating helical thread 20, giving the molecules a velocity component and tending to cause the molecules to have the same direction of motion as the surface against which they strike. The molecules may be urged through the molecular drag portion 17 in this manner and exit the molecular drag portion 17 at a higher pressure than that at which they entered. Further details regarding exemplary molecular drag portions and their various components can be found in U.S. Pat. No. 5,772,395, which is incorporated herein by reference in its entirety.
Molecular drag portion 17 may have an alternate configuration, for example, as shown in
Each molecular drag portion 17 may be in flow communication with other molecular drag portions 17. Each molecular drag portion 17 may be disposed radially inward or outward from other molecular drag portions 17. Each molecular drag portion 17 may have a different configuration. For example, the helical threads 20 in each molecular drag portion 17 may have a different length than helical threads 20 in other molecular drag portions 17. Molecular drag portions 17 may be disposed radially outward from turbomolecular pump 10. Each molecular drag portion 17 may be configured to increase a pressure of the substance while the substance flows through the molecular drag portion 17, and then exhaust the substance to a more radially outer molecular drag portion 17 until the substance is exhausted by the final molecular drag portion 17 to the dry pump 30.
The dry pump 30 may be a pump configured to provide transition flow and/or viscous flow of the substance such that molecules of the substance are more likely to collide with each other rather than at least one interior wall 35 (
Dry pump 30 may have an alternate configuration, for example, as shown in
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In operation, blade 352 may rotate relative to channel 372. A substance may enter second portion 372b of channel 372 via inlet 391. Blade 352 may then cause the substance to flow in the same direction as the rotation of blade 352, for example, in a substantially oval-like and/or spiral-like pattern. The substance may then exit second portion 372b of channel 372 via outlet 392. The substance may then be sent to another blade 352 and channel 372 combination, or may be exhausted from pump 1.
As shown in
In some examples, the turbomolecular pump 10 may be coupled to the dry pump 30 such that the turbomolecular pump 10 and the dry pump 30 are positioned no more than about 20 centimeters from one another. In such a configuration, the outlet 12 of the turbomolecular pump 10 may be connected to the inlet 31 of the dry pump 30 such that the outlet 12 and inlet 31 are in flow communication with each other so as to pass the substance pumped from the turbomolecular pump 10 into the dry pump 30.
In one exemplary embodiment, as shown in
In another exemplary embodiment, as shown in
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In one example of an abatement process, the abatement device 60 may receive a substance flow including perfluorocarbons (“PFCs”) via at least one of the turbomolecular pump 10 and the dry pump 30. The abatement device 60 may then take the PFCs and break them up into hydrogen flouride (“HF”). While HF may be more hazardous than PFCs, unlike PFCs, HF may be readily dissolved in water. Thus dissolved, the HF may now be more easily handled and/or disposed. More details concerning this type of abatement is disclosed in U.S. Pat. No. 6,530,977, which is incorporated herein by reference in its entirety.
Another example of abatement device 60 is disclosed in U.S. Pat. No. 6,358,485, which is incorporated herein by reference in its entirety. In such an abatement device, a gas stream containing trimethylvinylsilane (TMVS) is exposed to a gas stream containing copper oxide and/or manganese oxide, which chemically combine to form a non-toxic byproduct. This non-toxic byproduct may then be readily and more easily disposed.
In another example of an abatement process, the abatement device 60 may receive a substance flow including fluorine via at least one of the turbomolecular pump 10 and the dry pump 30. The abatement device 60 may take the fluorine and burn it (or otherwise heat it and provide a hydrogen atom source) so as to form HF. The HF may then be dissolved in water and disposed of.
In yet a further example of an abatement process, the abatement device 60 may receive a substance flow including pyrophoric gas(es) (e.g., silane) via at least one of the turbomolecular pump 10 and the dry pump 30. The abatement device 60 may take the pyrophoric gas(es) and mix it with air heated to at least 300 degrees Celsius. Such mixing may reduce the amount of pyrophoric gas(es) that exits the abatement device, thus making the substance flow safer and easier to handle. More details concerning an example of this type of abatement are disclosed in U.S. Pat. No. 6,530,977, which is incorporated herein by reference in its entirety.
The abatement device 60 may be positioned at any location so as to receive substance passing to, or flowing from, either or both of the pumps 10, 30. If the abatement device 60 operates more efficiently at lower pressures, the abatement device 60 may be positioned downstream from the turbomolecular pump 10 and upstream from the dry pump 30, as shown in
In some examples, the vacuum processing chamber 2 may be associated with a semiconductor wafer processing arrangement where very low levels of water vapor may be used and/or created. For example, when a vacuum is created in the vacuum processing chamber 2, water molecules may be collected on the inner surfaces of the chamber 2. When the substance flow exits the vacuum chamber 2, it may be desirable to substantially prevent any of the water vapor from reentering the vacuum processing chamber 2.
The cryogenic water pump 70 may remove the water vapor from the substance flow by causing the water vapor to freeze and become trapped on cryogenically cooled surfaces of the cryogenic water pump 70. If the temperature of the surfaces of the cryogenic water pump 70 is lowered enough, the cryogenic water pump 70 may also trap other materials on its surface, for example lower vapour pressure precursors used within the semiconductor process. If the temperature is lowered further, then gases like carbon dioxide and argon may be trapped, although these gases may be more commonly handled downstream from the turbomolecular pump and/or the dry pump. Avoiding oxygen condensation may also be desirable, hence the use of a cryogenic pump for water but turbomolecular pump for gases.
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In some examples, rather than having a wired connection, a wireless link may provide communication between the common controller 90 and the turbomolecular pump 10, the dry pump 30, the abatement 60, and/or the cryogenic water pump 70.
The turbomolecular pump 10, the dry pump 30, the abatement 60, and/or the cryogenic water pump 70 may share common connections. For example, the turbomolecular pump 10, the dry pump 30, the abatement 60, and/or the cryogenic water pump 70 may share a common power connection 100 (
As shown in
The turbomolecular pump 10 and the dry pump 30 may share a common nitrogen distribution route 102. Nitrogen may be used to protect certain elements of the pumps 10, 30 from contamination. For example, the pumps 10, 30 may each have a motor and bearing arrangement, and the nitrogen may be used to keep potentially corrosive process materials away from the bearings or other portions in the motors of the pumps 10, 30.
Nitrogen may additionally (or alternatively) be used to dilute gas flowing through at least one of the pumps 10, 30. For example, if a very light gas, such as hydrogen or helium, is being pumped through the pumps 10, 30, the light gas may move around very quickly, and thus may have a tendency to flow undesirably backwards through the turbomolecular pump 10 and the dry pump 30. By adding nitrogen, the density of the chemical flow may be increased and the backwards flow of the light gas species may be substantially reduced and/or eliminated.
Nitrogen may additionally (or alternatively) be used to substantially prevent condensation within at least one of the pumps 10, 30. For example, water may condense out of the substance flow as the substance flow is brought up to atmospheric pressure. By adding nitrogen to the substance flow, the water within the substance flow passing through at least one of the pumps 10, 30 may be diluted, and thus condensation of the water may be substantially limited or prevented by keeping the water in the vapor phase. In addition to limiting condensation of water, nitrogen may be used to limit condensation of other materials, such as, for example, silicon fluoride and silicon bromide.
Nitrogen may additionally (or alternatively) be used to dilute a flammable material so that it no longer has a flammable concentration.
As shown in
The invention may have several advantages. For example, the invention may operate at a greater efficiency than pumps positioned at further distances relative to each other. In another example, conductance losses present during the use of pumps positioned at further distances relative to each other may be minimized and/or substantially eliminated, for example, due to a reduction in the length of the substance flow paths. In another example, the invention may take up less space than pumps positioned at further distances relative to each other and require less energy, important advantages in an industry where space and power consumption is at a premium. In a further example, because the exhaust from the apparatus may be greater than or equal to about 100 millibar, double containment of the apparatus may not be necessary as any sub-atmospheric leaks may be inwards.
It will be apparent to those skilled in the art that various modifications and variations can be made to the structure described herein. This, it should be understood that the invention is not limited to the subject matter discussed in the specification and shown in the drawings. Rather, the present invention is intended to include modifications and variations.
