JP2006514157A - View wing window cleaning equipment - Google Patents

Abstract

【Task】
A view wing port is provided for a process chamber having a view wing window cleaning device, a view wing window, and a fixture. A view wing window cleaning device is coupled to the fixture and is positioned between the view wing window and the process chamber so as to form a cleaning plasma in a cleaning plasma region of the fixture. It is configured. In addition, the fixture is configured to reduce the amount of by-products on the surface of the view wing window from the process chamber by preventing the by-products from moving toward the window.

Description

  The present invention provides for this view wing by either (1) removing accumulated by-products from the view wing window, or (2) preventing accumulation of by-products in the view wing window, or (3) both. The present invention relates to an apparatus for maintaining the cleanliness of a window.

  This application is entitled “Inductively Coupled High Density Plasma Source” and is filed on March 23, 2001, US Application No. No. 60 / 277,965, entitled “Inductively coupled high density plasma source” and filed March 23, 2001. No. 60 / 277,966, filed on Mar. 25, 2002, claiming priority. PCT / US02 / 22080, filed September 19, 2002, US provisional application no. 60 / 411,760 and claims priority based on this. The entire contents of all these applications are hereby incorporated by reference.

  In the fabrication and manufacture of semiconductor devices, the use of plasma processing is a widely accepted practice to facilitate the many etching and deposition processes necessary during the production of the device. For example, a silicon wafer that provides a circuit board for fabricating a silicon-based semiconductor device is introduced into a plasma processing chamber and exposed to the process plasma during various steps. In this step, material is removed (etching) or added (deposition) from selected areas of the substrate.

  Optical plasma detection is frequently used in plasma processing to characterize plasma processes and detect process endpoints. Such detection requires optical access to this region of plasma processing through a window that is sufficiently transparent to the light wavelength of interest and provides a reliable vacuum seal. Most light detection methods require the entire spectrum to be obtained using a scanning monochromator, spectrograph or similar device. In these cases, it is important that the window remains highly transparent throughout the spectral region of interest.

  One of the most frequently encountered problems in light detection of plasma processes is film deposition on the optical detection window or observation view wing port. The observed view wing port contacts the process plasma on one side, and in typical plasma etching and deposition chemistry, the local plasma state at the view wing port is absorbed by the process plasma. Causes the formation of a film consisting of chemical species present in the plasma. During wafer processing, this film grows at this view wing port, leading to a gradual degradation of the resulting optical signal. This degradation leads to non-reproducibility of optical signal measurements made under the same conditions. This non-reproducibility of the optical signal can affect the control mechanism of the processing tool that is responsive to the input from the optical detection sensor.

  In summary, regardless of the particular optical method used, the observation viewing port in the chamber wall, such as the viewing port shown in FIG. 1, must be kept relatively clean. If not, the data collected by observation or experiment can be inaccurate. (FIG. 1 illustrates one such viewing window 400a attached to the plasma chamber 200a by standard ISO-KF hardware 300a.)

  For this, it is necessary to remove and clean the accumulated or deposited material from this view wing port. Previously, this meant removing this viewing port and manually cleaning this glass. However, cleaning the viewing port in this way was an expensive problem because of the time and labor required to perform this task.

  The present invention preferably provides an apparatus and method for cleaning the viewing wing window of a process chamber without increasing the cost and labor of removing the viewing window. As a result, the data obtained by observing the process chamber is accurate. Thus, the present invention describes an apparatus and method for cleaning a window without having to remove it.

  In accordance with the first aspect of the invention, by-products (or other materials) are removed from the viewing window of the process chamber by physical or chemical etching. Preferably, the secondary plasma source is mounted adjacent to the viewing window. The plasma generated by the secondary plasma source etches by-products accumulated in the viewing window.

  According to the second embodiment, preferably the cleanness of the view wing window attached to the process chamber is maintained by reducing the amount of by-products that accumulate in the view wing window in the first place. Yes.

  Preferably, the viewing window is supported at a predetermined position or location relative to the process chamber such that the amount of by-products toward the viewing window is substantially reduced.

  Moreover, in yet another aspect, a plurality of magnets reduces byproduct accumulation from the process chamber to the view wing window. These magnets generate a magnetic field that reduces the amount of by-products in the process chamber reaching this view wing window. In yet another embodiment, a gas injection mechanism reduces byproduct accumulation from the process chamber to the view wing window by applying pressure to a portion of the process chamber near the view wing window. I am letting.

  Any combination of the above aspects can be used to either remove by-products from the view wing window or to reduce by-product accumulation in the view wing window.

  A more complete appreciation of the invention and many of the attendant advantages will become readily apparent when considered in conjunction with the accompanying detailed description, particularly when taken in conjunction with the accompanying drawings.

  Referring now to the drawings in which like reference numerals designate identical or corresponding parts throughout the several views, the cleaning device for the view wing window is (1) from the process chamber accumulated in the view wing window. Or (2) an apparatus for reducing the number of particles towards the view wing window, or (3) both.

  The present invention provides an apparatus and method for handling known plasma chamber view wing window difficulties. In accordance with the present invention, referring to FIG. 2, the process chamber 200 is a large chamber in which plasma can be generated. The process chamber 200 includes a view wing window 400 that allows optical access to the process chamber, a fixture 300 that couples a view wing port to the process chamber, and a view wing window cleaning device 100. A view wing port 10 is provided. Further, the fixture 300 separates the view wing window 400 from the process chamber 200. For example, the fixture 300 can be configured to be compatible with standard ISO-KF hardware 301. The fitting can also have a connecting member 302 that secures the various parts of the fitting together and allows the fitting to be extended to a desired length. The view wing window 400 and the fixture 300 provide a view into the interior of the process chamber 200 that allows the process in the chamber 200 to be monitored.

  According to the first embodiment, the by-product of the process chamber 200 is removed from the view wing window 400. The apparatus 100 for cleaning the view wing window is preferably located on the fixture 300 adjacent to the view wing window 400 outside the process chamber 200. The first interface portion 305 is located at a connection point between the fixture 300 and the view wing window cleaning device 100 and faces the process chamber 200. The second interface portion 310 is located on the opposite side of the first interface portion 305 and faces the view wing window 400. The plasma generated by the view wing window cleaning apparatus 100 removes by-products from the process chamber 200 from the view window 400. In order to achieve removal, the interface portion 310 is close enough to the view wing window 400 so that the plasma generated by the view wing window cleaning device 100 removes by-products of the view wing window. Is located. The removal process is a physical or chemical etching process or a combination of physical and chemical etching processes.

  Referring to FIGS. 3A and 3B, the view wing window cleaning apparatus 100 includes at least two components, an outer housing 130 and a plasma source 140. The housing 130 provides structural support for the plasma source 140 in addition to shielding the RF energy used to energize the plasma source 140.

  The housing also has the connecting member 302. The connection member 302 provides a vacuum-tight connection with the fixture member 300, provides support for the view wing window cleaning device 100 of the fixture 300, and the various It makes necessary maintenance possible.

  The plasma source 140 further includes an impedance matching assembly 141 and a plasma generator 150. This impedance matching assembly 141 provides an RF source 138 through the plasma generator 150 by providing impedance matching in order to resist the inherent reactive impedance component inherent in the plasma generation mechanism. To the plasma in the cleaning plasma region 155 is maximized. Typically, an adjustable component, such as a vacuum variable capacitor, in the impedance matching assembly 141 provides measurements of forward and reflected RF power. It is operated by an automatic control mechanism (not shown). The design of impedance matching circuits for plasma generation and the use of both automatic and manual are well known to those skilled in the art of RF mechanism and plasma source design. In accordance with the present invention, components of a known matched assembly are employed that run in a small space that can be used in the view wing window cleaning apparatus 100. For example, details of the design of the plasma source 140 are described in US application number filed March 23, 2001, entitled “Inductively Coupled High-Density Plasma Source,” hereby incorporated by reference in its entirety. No. No. 60 / 277,965, entitled “Inductively coupled high density plasma source” and filed March 23, 2001. No. 60 / 277,966, filed on Mar. 25, 2002, pending international application no. PCT / US02 / 22080 is given for a compact inductively coupled plasma source.

  Specifically, for example, the impedance matching assembly 141 includes a first variable capacitor 142 having an input coupled to the output of the RF source 138 and an output coupled to the first terminal 143 of the induction coil 151; And a second variable capacitor 144 having a first terminal coupled to the first terminal of the induction coil and a second terminal coupled to the second terminal 145 of the induction coil 151. . The second terminal of the induction coil 151 and the second terminal of the variable capacitor 144 are coupled to ground. For example, the variable capacitor 142 and the variable capacitor 144 can be one or more fixed capacitors.

The plasma generator 150 may include the induction coil 151 coupled to the impedance matching assembly 141 and positioned to surround the process tube 152. Alternatively, another impedance matching assembly arrangement can be used. Ionization from the gas injection mechanism used to form a process plasma in the process chamber 200 to the plasma region 155 for cleaning during the wafer processing step or during the time between wafer processing steps. Possible gases can be supplied. Alternatively, a secondary gas injection mechanism coupled to the view wing window cleaning device 100 or the fixture member 300 may provide ionizable gas and / or dissociative gas. It is used for local injection into the plasma region 155 for cleaning. For example, if the view wing window cleaning (etching) process is a physical process, a heavy inert gas such as argon, krypton, xenon, or the like may be used. Conversely, if the view wing window cleaning (etching) process is preferably a chemical process, reactivity such as NF ₃ , CF ₄ , SF ₆ , C ₂ F ₆ , CCl ₄ , C ₂ Cl ₆ is used. Of gas can be supplied. When the view wing window cleaning (etching) process has both physical and chemical processes, a combination of heavy and reactive gases can be used.

  Alternatively, a vacuum sealable gas injection hole (not shown) may be provided along the process tube through which the injected gas travels to the plasma formation region. it can. When the view wing window cleaning device 100 is in operation, RF power is coupled from the RF source 138 to the cleaning plasma region 155 through the impedance matching assembly 141 using the induction coil 151. Is done. This combined RF field generates a plasma that is used to clean the view wing window in the presence of the injected gas.

  Preferably, exhaust gas is pumped from the cleaning plasma region into the plasma chamber (not shown) or directly pumped out of the plasma source (not shown). . When the exhaust gas is exhausted through the process chamber, the process chamber pump mechanism already in place can be used. When this exhaust gas is directly exhausted from the cleaning plasma region, a secondary pump mechanism (not shown) is installed, or without putting the cleaning gas into the process chamber, A secondary vacuum line (not shown) is installed for direct discharge to the inlet of the process chamber pump mechanism. For example, when a vacuum pump mechanism is accessing the process chamber 200 from the side, the fixture 300 connects the process chamber 200 substantially to the inlet of the pump mechanism. A vacuum line is coupled directly to the interior of the fitting 300 to the outlet of the pump, thereby bypassing the interior of the process chamber 200. Can be done.

  A gate valve (not shown) that isolates the plasma source from the process chamber in order for exhaust gases to be efficiently pumped into the process chamber during exhaust of the view wing window cleaning apparatus 100. ) May also be used. Such a valve will ensure that exhaust gas is pumped out of the plasma source and the fixture into the process chamber without venting from the process chamber to the fixture. Let's go.

  In the second embodiment, the amount of by-product from the process chamber that diffuses into the view wing window is reduced while the view wing window cleaning device is provided. The reduction in transport has been established by using various aspects as noted below. These aspects position the view wing window relative to the process chamber such that the amount of by-products that reach the view wing window is reduced and reduce cross-field electron transport. One or a combination of using a magnet for the purpose and applying pressure to the fixture 300 to achieve a reverse pressure gradient against the material coming from the process chamber However, it is not limited to these.

  The first aspect of this second embodiment is described with reference to FIG. The view wing window 400 is attached to the process chamber 200 by a fixture 300 at a predetermined position of the process chamber. For example, this location can be determined based on experimental data indicating the location where transport of reaction by-products through the fixture is reduced. Furthermore, the view wing window cleaning apparatus 100 can be positioned sufficiently far from the process chamber such that the amount of reaction by-products that accumulate in the view wing window 400 is substantially reduced. . In addition, the angle α shown in FIG. 4 can be reduced by a reaction by-product by avoiding a direct line-of-site between the view wing window 400 and the process chamber 200. This can be chosen on the basis of experimental data showing the reduced transport to the view wing window 400.

  Nevertheless, this angle α is so great that it avoids a clear-line-of sight from the view wing window to the area inside the process chamber where the plasma state is measured. Don't be big.

 In addition to the embodiment of FIG. 4, the fixture 300 can be modified to have a magnet, as shown in FIGS. 5A and 5B. 5A and 5B, a plurality of magnets 160A-160G are arranged to generate a magnetic field that prevents cross-field electron transport between the plasma chamber 200 and the view wing window 400. Yes. Preferably, these magnets 160A to 160G are disposed on the inner surface of the fixture 300. As a result, they generate a magnetic field that substantially extends across the fixture 300 and are either a process plasma in the process chamber 200 or a cleaning plasma in the view wing window cleaning device 100. Constitutes a field strength sufficient to prevent cross-field transport of electrons generated by For example, the strength of this magnetic field is desirably at least 200 Gauss. Reduction of cross-region electron transport has several advantages, such as separation of the process plasma from the cleaning plasma, separation of process chemistry and cleaning chemistry. Such a magnet can be a permanent magnet or an electromagnet that can be controlled as needed (ie, the strength of this magnetic field can be changed by controlling the level of the signal to the electromagnet. it can).

  The polarity of these magnets 160A-160G can be arranged to form a cusp field (ie, the polarity of each of these magnets is the same. For example, the north pole is oriented inward. ing). Alternatively, the polarity of adjacent magnets can be changed. Instead, the polarity of at least one magnet is different from this remaining magnet.

  Referring to FIG. 6, a gas injection mechanism 170 is provided to generate pressure inside the fixture to reduce the amount of reaction by-products entering the fixture 300 that diffuse into the view wing window. It is installed inside the fixture 300. A conduit 172 couples a gas supply mechanism (not shown) to the inlet or array of inlets of the fixture 300. This gas supply mechanism (not shown) can be coupled to the gas injection mechanism 170 by a connector 174. The connector 174 can be, for example, a VCR fitting or a Swagelock fitting. The gas supply mechanism (not shown) supplies an inert gas (ie, a gas such as noble gas, nitrogen, etc.) through the conduit 172 and through the inlet 171 into the fixture 300. ing. Since a pressure gradient is established inside the fixture 300, the amount of reaction by-products formed in the view wing window 400 is substantially reduced.

  Alternatively, a flow restrictor device in the fixture 300 can be used to facilitate the formation of a pressure gradient at a low gas flow rate. . Instead, a reactive gas is injected through the gas injection mechanism during the window cleaning process. Instead, this gas is injected and directed to strike the surface of the view wing window. Instead, the flow of gas directed to impinge on this view wing window is pulsed.

  According to the present invention, any of the above aspects can be simultaneously combined with any other aspect in various combinations. For example, the cleaning device for the view wing window may be attached between the view wing window and a plurality of magnets. Thus, the combination of the plurality of magnets and the device for cleaning the view wing window can cause a very large reduction in the amount of reaction by-products accumulated in the view wing window. Similarly, the plurality of magnets, the gas injection mechanism, and the view wing window cleaning mechanism can all be installed on the fixture to affect even greater reductions.

  In particular, referring to FIG. 7, the view wing window cleaning device 100, the positioning of the view wing window 400, the plurality of magnets 160A to 160G, and the gas injection system 170 are all coupled at one time. Can do. As shown in FIG. 7, the fixture 300 can be used to install the view wing window 400 at a specific location in the process chamber. The apparatus 100 for cleaning the view wing window is used to physically or chemically etch by-products on the surface of the view wing window 400 at the end of the fixture 300 near the view wing window. It is installed in the correct position. The two sets of magnets 160A to 160G are arranged in parallel to each other in the fixture. The gas injection mechanism 170 applies pressure to the fixture 300 and further reduces the amount of reaction by-products reaching the view wing window.

  The present invention provides a view wing window having a view wing window, means for reducing the amount of by-products on the surface of the view wing window from the process chamber, and a connecting member coupling the means for reducing to the process chamber. It can also be described as a cleaning device.

  The present invention includes the steps of: placing a wafer inside a process chamber; generating a plasma inside the process chamber; and a view wing window coupled to the process chamber without separating the view wing window from the process chamber. And the method of cleaning the view wing window with the step of reducing the amount of by-products from the process chamber.

  Numerous modifications and variations of the present invention are possible under the above suggestions. Thus, within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein.

FIG. 3 is a view of a known view wing window in which the view wing window is directly attached to the process chamber. FIG. 5 is a view of a view wing window cleaning device mounted in close proximity to a view wing window that is a short distance away from the process chamber. It is the schematic of the plasma source of FIG. An enlarged view of the matching assembly and the upper part of the plasma resonance coil. It is a side view of the view wing window attached with the predetermined inclination with respect to the process chamber. FIG. 6 is a side view of a plurality of magnets arranged to generate a magnetic field that prevents by-products from heading toward the view wing window. FIG. 6 is a cross-sectional view of a plurality of magnets arranged to generate a magnetic field that prevents a by-product from heading toward the view wing window. FIG. 5 is a side view of a gas injection mechanism that is used to apply pressure to an extension that separates the view wing window from the process chamber. It is a figure of the example of a coupling | bonding related to each other of said aspect.

Claims (33)

A viewing window that allows optical access to the process chamber;
A fixture for coupling the viewing window to the process chamber;
A view wing coupled to the fixture and positioned between the view wing window and the process chamber and comprising a view wing window cleaning device for forming a cleaning plasma in a cleaning plasma region of the fixture. port.   2. The view wing port according to claim 1, wherein the view wing window cleaning device includes an RF generation source and a plasma source.   The view wing port according to claim 2, wherein the view wing window cleaning device further includes an impedance matching assembly and a plasma generator.   The view wing port according to claim 3, wherein the plasma generator has an induction coil.   The fixture of claim 1, further comprising at least one magnet array coupled to the fixture.   6. The fixture of claim 5, wherein at least one of the array magnets is a permanent magnet.   6. The fixture of claim 5, wherein at least one of the array magnets is an electromagnet.   The fixture of claim 1, further comprising a gas injection mechanism coupled to the cleaning plasma region.   9. The fixture according to claim 8, wherein the cleaning plasma etches by-products deposited on the view wing window by physical etching.   The fixture according to claim 9, wherein the gas injection mechanism supplies at least one of argon, krypton, and xenon.   9. The fixture according to claim 8, wherein the cleaning plasma etches by-products deposited on the view wing window by chemical etching. It said gas injection mechanism, NF ₃ and CF _4, SF ₆ and _C 2 _{F 6} and CCl ₄ and fitting of claim 11 for supplying at least one of the _C 2 Cl _6.   9. The fixture of claim 8, wherein the cleaning plasma etches by-products deposited on the view wing window by physical and chemical etching. Said gas injection mechanism is at least one of argon and krypton and xenon, the NF ₃ and CF ₃ and SF ₆ and _C 2 _{F 9} and CCl ₄ and _C 2 Cl ₆ and at least one of the supplying claim 13 Mounting tool.   The fixture of claim 1, further comprising a view wing window support configured to dispose the view wing window at a predetermined position relative to the position of the process chamber.   16. The fixture of claim 15, wherein the predetermined location is selected such that a substantial amount of by-product does not reach the view wing window.   9. The gas injection mechanism according to claim 8, wherein the gas injection mechanism is configured to flow a gas into the cleaning plasma region so that a pressure substantially opposite to a direction in which a by-product is generated is generated in the cleaning plasma region. Mounting tool.   9. The fixture of claim 8, further comprising at least one magnet array coupled to the fixture.   19. The fixture of claim 18, wherein at least one of the array magnets is a permanent magnet.   19. The fixture of claim 18, wherein at least one of the array magnets is an electromagnet. A view wing port coupled to the process chamber;
This view wing port
A view wing window that allows optical access to the process chamber;
A fixture for coupling the viewing window to the process chamber;
A view wing window cleaning device coupled to the fixture and positioned between the view wing window and the process chamber and configured to form a cleaning plasma in a cleaning plasma region of the fixture; A process chamber comprising:   The process chamber of claim 21, wherein the fixture further comprises a gas injection mechanism connected to the cleaning plasma region.   The process chamber of claim 21, wherein the view wing window cleaning apparatus comprises an RF source.   The process chamber of claim 21, wherein the view wing window cleaning device comprises a plasma generator.   The process chamber of claim 21, wherein the fixture further comprises at least one magnet array connected to the fixture.   26. The process chamber of claim 25, wherein at least one of the array magnets is a permanent magnet.   26. The process chamber of claim 25, wherein at least one of the array magnets is an electromagnet. Providing a view wing window cleaning device positioned between the view wing window and the process chamber and shaped to form a cleaning plasma;
Cleaning the view wing window for a process chamber comprising forming the cleaning plasma in a region between the view wing window and the process chamber to facilitate cleaning of the view wing window. Method.   29. The method of claim 28, further comprising generating a magnetic field that prevents cross-region electron transport between the plasma chamber and the view wing window.   The method further comprises supplying a gas such that a pressure substantially opposite to the direction of by-products from the process chamber is generated in a region between the view wing window and the process chamber. 28 methods.   The method further comprises disposing the view wing window at a predetermined position selected such that a substantial amount of by-product does not reach the view wing window relative to the position of the process chamber. Item 28. The method according to Item 28.   29. The method of claim 28, wherein the cleaning plasma is formed using an RF source and a plasma generator. The cleaning plasma contains at least one of by-products accumulated in the view wing window among argon, krypton, xenon, NF ₃ , CF ₄ , SF ₆ , C ₂ F ₆ , CCl ₄ and C ₂ Cl _6. 29. The method of claim 28, wherein etching is performed using one.

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