Patent Grant
7534363
Semiconductor processing includes deposition processes such as chemical vapor deposition (CVD) of metal, dielectric and semiconducting materials, etching of such layers, ashing of photoresist masking layers, etc. Such semiconductor processes are typically carried out in vacuum chambers wherein process gas is used to treat a substrate such as a semiconductor wafer, flat panel display substrate, etc. The process gas can be supplied to the interior of the vacuum chamber by a gas distribution system such as a showerhead, a gas distribution ring, gas injectors, etc. Reactors having plural gas distribution systems are disclosed in U.S. Pat. Nos. 5,134,965; 5,415,728; 5,522,934; 5,614,055; 5,772,771; 6,013,155; and 6,042,687.
In the case of etching, plasma etching is conventionally used to etch metal, dielectric and semiconducting materials. A plasma etch reactor typically includes a pedestal supporting the silicon wafer on a bottom electrode, an energy source which energizes process gas into a plasma state, and a process gas source supplying process gas to the chamber.
A common requirement in integrated circuit fabrication is the etching of openings such as contacts and vias in dielectric materials. The dielectric materials include doped silicon oxide such as fluorinated silicon oxide (FSG), undoped silicon oxide such as silicon dioxide, silicate glasses such as boron phosphate silicate glass (BPSG) and phosphate silicate glass (PSG), doped or undoped thermally grown silicon oxide, doped or undoped TEOS deposited silicon oxide, etc. The dielectric dopants include boron, phosphorus and/or arsenic. The dielectric can overlie a conductive or semiconductive layer such as polycrystalline silicon, metals such as aluminum, copper, titanium, tungsten, molybdenum or alloys thereof, nitrides such as titanium nitride, metal silicides such as titanium silicide, cobalt silicide, tungsten silicide, molybdenum silicide, etc. A plasma etching technique, wherein a parallel plate plasma reactor is used for etching openings in silicon oxide, is disclosed in U.S. Pat. No. 5,013,398.
U.S. Pat. No. 5,736,457 describes single and dual “damascene” metallization processes. In the “single damascene” approach, vias and conductors are formed in separate steps wherein a metallization pattern for either conductors or vias is etched into a dielectric layer, a metal layer is filled into the etched grooves or via holes in the dielectric layer, and the excess metal is removed by chemical mechanical planarization (CMP) or by an etch back process. In the “dual damascene” approach, the metallization patterns for the vias and conductors are etched in a dielectric layer and the etched grooves and via openings are filled with metal in a single metal filling and excess metal removal process.
Various methods in semiconductor processing, such as damascene metallization processes, require methods for removing organic material over substrates, such as stripping a photoresist mask, etching an organic bottom antireflective coating (BARC), removing a via plug, or etching an organic dielectric layer.
To achieve the foregoing and in accordance with the purpose of the present invention a method for removing organic material over a substrate is provided. The substrate is placed in a plasma processing chamber. A first gas is provided to an inner zone within the plasma processing chamber. A second gas is provided to an outer zone of the plasma processing chamber, wherein the outer zone surrounds the inner zone and the second gas has a carbon containing component, wherein a concentration of the carbon containing component of the second gas is greater than a concentration of the carbon containing component in the first gas. Plasmas are simultaneously generated from the first gas and second gas. Some of the organic material is removed using the generated plasmas.
In another manifestation of the invention a method for stripping a photoresist mask over a substrate is provided. The substrate is placed in a plasma processing chamber. A first gas is provided to an inner zone within the plasma processing chamber. A second gas is provided to the outer zone of the plasma processing chamber, wherein the outer zone surrounds the inner zone and the first gas is different than the second gas. Plasmas are simultaneously generated from the first gas and second gas. The photoresist mask is stripped, wherein the photoresist mask is stripped by the plasmas from the first gas and second gas.
In another manifestation of the invention a method for removing plugs in a via of a dual damascene structure over a substrate is provided. The substrate with a dielectric layers with vias with via plugs is placed in a plasma processing chamber. A first gas is provided to an inner zone within the plasma processing chamber. A second gas is provided to the outer zone of the plasma processing chamber, wherein the outer zone surrounds the inner zone and the first gas is different than the second gas. Plasmas are simultaneously generated from the first gas and second gas. The vias plugs are removed by the plasmas from the first gas and the second gas.
These and other features of the present invention will be described in more detail below in the detailed description of the invention and in conjunction with the following figures.
The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:
FIG'S. 3A-C are cross-sectional views of a substrate in the processed according to the process shown in
FIG'S. 4A-B are schematic illustrations of a computer system that may be used as a controller.
The present invention will now be described in detail with reference to a few preferred embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process steps and/or structures have not been described in detail in order to not unnecessarily obscure the present invention.
To facilitate understanding,
In the specification and claims, a first gas is defined as a gas with a single component or with a plurality of components to form a gas mixture. A first gas is different than a second gas, only if the first gas and second gas have different components or the same components in different ratios. Different flow rates of gases with the same components at the same ratios are not different gases.
In a preferred embodiment of the invention, the plasma processing chamber uses a confined plasma system, which confines the plasma to a region above the wafer. Such a confined plasma system may use confinement rings, as disclosed in U.S. Pat. No. 6,019,060, by Eric Lenz, entitled “CAM-BASED ARRANGEMENT FOR POSITIONING CONFINEMENT RINGS IN A PLASMA PROCESSING CHAMBER”, issued Feb. 1, 2000, which is incorporated by reference for all purposes. Such a plasma confinement system is used in the 2300 Exelan chamber, made by Lam Research Corporation of Fremont, Calif.
Without being bound by theory, it is believed that in the removal of organic material from over a substrate, a loading effect at the edge of the substrate may be due to the lack of consumable organic material at the outer diameter of the substrate compared to the center of the substrate, which causes a non-uniform removal of organic material, where the organic material closer to the edge of the substrate is removed faster. As a result uneven etching or damage to a layer below the organic material may result. Providing a higher concentration of carbon containing component at the edge of the substrate has been found to provide a more uniform removal of the organic material.
Some of the carbon containing components that may be used in the invention are CH4, C2H4, CO, CH3F, CH2F2, and CF4. For some applications, it is preferable to use a fluorine free carbon containing component.
Some of the gases that are useful in removing the organic components are O2, O2/N2, O2/CO, O2, NH3, N2/H2, N2O, and H2O.
Stripping
One example of the inventive process provides a uniform stripping of a photoresist mask.
The substrate 308 is placed in a processing chamber where the low-k dielectric layer 304 is etched (step 212).
In this example of the implementation of the invention, an 2300 Exelan chamber, made by Lam Research Corporation of Fremont, Calif. is used as the etch process chamber for a 200 mm wafer, using a dual gas distribution system with a tuning gas as described above.
Gas is supplied to the confined plasma volume by gas source 510 through the ports 518 of the inner zone plate 512 and the outer zone plate 516, and is exhausted from the confined plasma volume through the confinement rings 502 and an exhaust port by the exhaust pump 520. The exhaust pump 520 forms a gas outlet for the plasma processing chamber. A RF source 548 is electrically connected to the lower electrode 508. Chamber walls 552 define a plasma enclosure in which the confinement rings 502, the gas distribution plate 504, and the lower electrode 508 are disposed. The RF source 548 may comprise a high frequency power source operating at 27 MHz and a low frequency power source operating at 2 MHz. The gas distribution plate 504 may be grounded. Different combinations of connecting RF power to the electrodes are possible. A controller 535 is controllably connected to the RF source 548, the exhaust pump 520, and the gas source 510.
FIG'S. 4A and 4B illustrate a computer system 800, which is suitable for using as the controller 535.
CPU 822 is also coupled to a variety of input/output devices, such as display 804, keyboard 810, mouse 812 and speakers 830. In general, an input/output device may be any of: video displays, track balls, mice, keyboards, microphones, touch-sensitive displays, transducer card readers, magnetic or paper tape readers, tablets, styluses, voice or handwriting recognizers, biometrics readers, or other computers. CPU 822 optionally may be coupled to another computer or telecommunications network using network interface 840. With such a network interface, it is contemplated that the CPU might receive information from the network, or might output information to the network in the course of performing the above-described method steps. Furthermore, method embodiments of the present invention may execute solely upon CPU 822 or may execute over a network such as the Internet in conjunction with a remote CPU that shares a portion of the processing.
In addition, embodiments of the present invention further relate to computer storage products with a computer-readable medium that have computer code thereon for performing various computer-implemented operations. The media and computer code may be those specially designed and constructed for the purposes of the present invention, or they may be of the kind well known and available to those having skill in the computer software arts. Examples of computer-readable media include, but are not limited to: magnetic media such as hard disks, floppy disks, and magnetic tape; optical media such as CD-ROMs and holographic devices; magneto-optical media such as floptical disks; and hardware devices that are specially configured to store and execute program code, such as application-specific integrated circuits (ASICs), programmable logic devices (PLDs) and ROM and RAM devices. Examples of computer code include machine code, such as produced by a compiler, and files containing higher level code that are executed by a computer using an interpreter. Computer readable media may also be computer code transmitted by a computer data signal embodied in a carrier wave and representing a sequence of instructions that are executable by a processor.
A plasma dry etch may be used to etch the low-k dielectric layer 304, which forms an opening 324 under the aperture 320 in the patterned resist mask 316, as shown in
A uniform stripping process is then provided to remove the photoresist mask 316 without damaging the low-k dielectric layer. To provide the uniform stripping process, a first gas is provided to the inner zone 512 (step 216). In this example, the first gas is pure O2. A second gas is provided to the outer zone 516 (step 220). In this example, the second gas is a mixture of O2 for stripping and C2H4 as the carbon containing gas. Plasmas are generated from the first and second gases (step 224). The plasmas are used to provide a uniform photoresist strip (step 228).
Therefore, in this example none of the carbon containing gas is provided directly to the inner zone. In one implementation of this, a dual gas feed divides the flow of O2 between the inner zone and outer zone. A tuning gas of C2H4 is then added only to the outer zone. In an example of a recipe, the chamber pressure is set at 20 mTorr. The lower electrode provides 600 Watts at 27 MHz and 0 Watts at 2 MHz. 300 sccm of O2 is provided to the chamber, with the addition of a C2H4 tuning gas to only the outer zone. This is maintained for 60 seconds.
A preferred stripping process would have a chamber pressure between 0 and 1,000 mTorr, with a lower frequency (ie. 2 MHz) power of between 0-1,000 Watts, a higher frequency (i.e. 27 MHz) power between 50-1,000 Watts, an O2 flow between 20-2,000 sccm, and a C2H4 addition to the outer region only of between 10-2,000sccm.
A more preferred stripping process would have a chamber pressure between 1and 500 mTorr, with a lower frequency (ie. 2 MHz) power of between 0-500 Watts, a higher frequency (i.e. 27 MHz) power between 100-900 Watts, an O2 flow between 100-1,000 sccm, and a C2H4 addition to the outer region only of between 20-1,000sccm.
In another embodiment, the first gas is pure O2 and the second gas is pure C2H4. There is sufficient loading so that enough O2 migrates from the inner zone to the outer zone to uniformly strip the photoresist.
In some etching processes etch residue may redeposited. It may be desirable to provide small amounts of fluorine to help remove the etch residue. In such a case, the carbon containing component may be CH3F. In a preferred embodiment, the CH3F is only provided to the outer zone. Although fluorine from CH3F is only directly provided to the outer zone, sufficient fluorine will migrate from the outer zone to the inner zone to reduce masking.
Etch Back
Another example of the inventive process provides a uniform via plug removal process.
The substrate may be placed in a processing chamber where the dielectric layer is etched (step 712). The plasma process chamber described above or other plasma process chambers may be used. A plasma dry etch is used to etch the dielectric layer to form trenches. The via plugs are used to reduce faceting during the trench etch. Fence formations may be formed during the trench etch around the via top. Some of the patterned resist mask is removed during the trench etch.
An etch back process is used to reduce the via plug height. By having the correct via height fence formations, and faceting of the vias is reduced or eliminated during the trench etch. Therefore the reduction of the via plug height is done after via etch and organic BARC fill but before trench patterning. To provide etch back process, a first gas is provided to the inner zone (step 716). In this example, the first gas is pure O2. A second gas is provided to the outer zone (step 720). In this example, the second gas is pure C2H4. Plasmas are generated from the first and second gases (step 724). The plasmas are used to remove the via plugs (step 728). This process may be used to also strip the remaining photoresist.
This process provides a uniform plug removal, which provides the advantage of consistently fence and facet free vias in the dual damascene structures.
Therefore, in this example none of the carbon containing gas is provided directly to the inner zone. In one implementation of this, a dual gas feed divides the flow of O2 between the inner zone and outer zone. A tuning gas of C2H4 is then added only to the outer zone. In an example of a recipe, the chamber pressure is set at 400mTorr. The lower electrode provides 0 Watts at 27 MHz and 600 Watts at 2 MHz. 300 sccm of O2 is provided to the chamber, with the addition of a C2H4 tuning gas to only the outer zone. This is maintained for 60 seconds.
A preferred uniform plug removal process would have a chamber pressure between 0 and 1,000 mTorr, with a lower frequency (ie. 2 MHz) power of between 50-1,000 Watts, a higher frequency (i.e. 27 MHz) power between 0-1,000Watts, an O2 flow between 20-2,000 sccm, and a C2H4 addition to the outer region only of between 10-2,000 sccm.
A more preferred uniform plug remvoal process would have a chamber pressure between 1 and 500 mTorr, with a lower frequency (ie. 2 MHz) power of between 0-500 Watts, a higher frequency (i.e. 27 MHz) power between 100-900Watts, an O2 flow between 100-1,000 sccm, and a C2H4 addition to the outer region only of between 20-1,000 sccm.
BARC Open
Another example of the inventive process provides a uniform BARC open process.
The substrate is placed in a processing chamber (step 812). The plasma process chamber described above or other plasma process chambers may be used. A uniform BARC open process is then provided to open the BARC layer. To provide the uniform BARC open process, a first gas is provided to the inner zone (step 816). In this example, the first gas is N2/H2. A second gas is provided to the outer zone (step 820). In this example, the second gas is pure C2H4. Plasmas are generated from the first and second gases (step 824). The plasmas are used to uniformly open the BARC layer (step 828).
Therefore, in this example none of the carbon containing gas is provided directly to the inner zone. In one implementation of this, a dual gas feed divides the flow of O2 between the inner zone and outer zone. A tuning gas of C2H4 is then added only to the outer zone. In an example of a recipe, the chamber pressure is set at 60mTorr. The lower electrode provides 600 Watts at 27 MHz and 0 Watts at 2 MHz. 300 sccm of O2 is provided to the chamber, with the addition of a C2H4 tuning gas to only the outer zone. This is maintained for 60 seconds.
A preferred BARC open process would have a chamber pressure between 0and 1,000 mTorr, with a lower frequency (ie. 2 MHz) power of between 0-1,000Watts, a higher frequency (i.e. 27 MHz) power between 50-1,000 Watts, an O2 flow between 20-2,000 sccm, and a C2H4 addition to the outer region only of between 10-2,000sccm.
A more preferred BARC open process would have a chamber pressure between 1 and 500 mTorr, with a lower frequency (ie. 2 MHz) power of between 0-500Watts, a higher frequency (i.e. 27 MHz) power between 100-900 Watts, an O2flow between 100-1,000 sccm, and a C2H4 addition to the outer region only of between 20-1,000 sccm.
Other examples may use the inventive process to uniformly etch a SiLK layer by providing a higher concentration of carbon containing component on the outer zone. This results in improved uniformity for trench and improved uniformity allows for less over etch in the case of vias.
Other components may be found in alternative to a carbon containing component that reduces loading to slow down the etching of the outer part of the wafer to provide a more uniform etch.
Other gas distribution embodiments may be used in other embodiments to provide a first gas to an inner zone and a second gas to an outer zone surrounding the inner zone where the first gas is different than the second gas. For example alternating ports in the outer zone area may provide different component gases, which together make up the second gas provided to the outer zone and/or alternating ports in the inner zone area may provide different component gases, which together make up the first gas, so that the first gas is different than the second gas. However, it is preferable that the component gases of the first gas be combined in the gas distribution system before the first gas is provided into the chamber and that the component gases of the second gas be combined in the gas distribution system before the second gas is provided into the chamber.
While this invention has been described in terms of several preferred embodiments, there are alterations, modifications, permutations, and substitute equivalents, which fall within the scope of this invention. It should also be noted that there are many alternative ways of implementing the methods and apparatuses of the present invention. It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and substitute equivalents as fall within the true spirit and scope of the present invention.
This application is a continuation-in-part of U.S. patent application Ser. No. 10/642,083 entitled “Uniform Etch System,” by Larsen et al. filed Aug. 14, 2003 now U.S. Pat. No. 7,371,332, which is a continuation-in-part of U.S. patent application Ser. No. 10/318,612 entitled “Gas Distribution System With Tuning Gas,” by Larsen et al. filed Dec. 13, 2002 now U.S. Pat. No. 7,169,231, which are both hereby incorporated by reference.
| Number | Name | Date | Kind |
|---|---|---|---|
| 4275752 | Collier et al. | Jun 1981 | A |
| 4369031 | Goldman et al. | Jan 1983 | A |
| 4812201 | Sakai et al. | Mar 1989 | A |
| 4835114 | Satou et al. | May 1989 | A |
| 4980204 | Fujii et al. | Dec 1990 | A |
| 5013398 | Long et al. | May 1991 | A |
| 5077875 | Hoke et al. | Jan 1992 | A |
| 5134965 | Tokuda et al. | Aug 1992 | A |
| 5200388 | Abe et al. | Apr 1993 | A |
| 5288325 | Gomi | Feb 1994 | A |
| 5310426 | Mori | May 1994 | A |
| 5313982 | Ohmi et al. | May 1994 | A |
| 5356515 | Tahara et al. | Oct 1994 | A |
| 5415728 | Hasegawa et al. | May 1995 | A |
| 5431738 | Murakami et al. | Jul 1995 | A |
| 5453124 | Moslehi et al. | Sep 1995 | A |
| 5455070 | Anderson et al. | Oct 1995 | A |
| 5460654 | Kikkawa et al. | Oct 1995 | A |
| 5496408 | Motoda et al. | Mar 1996 | A |
| 5522934 | Suzuki et al. | Jun 1996 | A |
| 5532190 | Goodyear et al. | Jul 1996 | A |
| 5589110 | Motoda et al. | Dec 1996 | A |
| 5614055 | Fairbairn et al. | Mar 1997 | A |
| 5620524 | Fan et al. | Apr 1997 | A |
| 5651825 | Nakahigashi et al. | Jul 1997 | A |
| 5702530 | Shan et al. | Dec 1997 | A |
| 5736457 | Zhao | Apr 1998 | A |
| 5744049 | Hills et al. | Apr 1998 | A |
| 5772771 | Li et al. | Jun 1998 | A |
| 5853484 | Jeong | Dec 1998 | A |
| 5865205 | Wilmer | Feb 1999 | A |
| 5916369 | Anderson et al. | Jun 1999 | A |
| 5950693 | Noah et al. | Sep 1999 | A |
| 5993555 | Hamilton | Nov 1999 | A |
| 6001172 | Bhandari et al. | Dec 1999 | A |
| 6009830 | Li et al. | Jan 2000 | A |
| 6013155 | McMillin et al. | Jan 2000 | A |
| 6015595 | Felts | Jan 2000 | A |
| 6019060 | Lenz | Feb 2000 | A |
| 6039074 | Raaijmakers et al. | Mar 2000 | A |
| 6042687 | Singh et al. | Mar 2000 | A |
| 6058958 | Benkowski et al. | May 2000 | A |
| 6090210 | Ballance et al. | Jul 2000 | A |
| 6119710 | Brown | Sep 2000 | A |
| 6125788 | Hills et al. | Oct 2000 | A |
| 6132515 | Gauthier | Oct 2000 | A |
| 6155289 | Carlsen et al. | Dec 2000 | A |
| 6192919 | Jackson et al. | Feb 2001 | B1 |
| 6224681 | Sivaramakrishnan et al. | May 2001 | B1 |
| 6251792 | Collins et al. | Jun 2001 | B1 |
| 6253783 | Carlsen et al. | Jul 2001 | B1 |
| 6296711 | Loan et al. | Oct 2001 | B1 |
| 6302139 | Dietz | Oct 2001 | B1 |
| 6315858 | Shinozuka et al. | Nov 2001 | B1 |
| 6333272 | McMillin et al. | Dec 2001 | B1 |
| 6418954 | Taylor et al. | Jul 2002 | B1 |
| 6457494 | Gregg et al. | Oct 2002 | B1 |
| 6508913 | McMillin et al. | Jan 2003 | B2 |
| 6589350 | Swartz | Jul 2003 | B1 |
| 6632322 | Gottscho et al. | Oct 2003 | B1 |
| 7169231 | Larson et al. | Jan 2007 | B2 |
| 20010047760 | Moslehi | Dec 2001 | A1 |
| 20020014207 | Sivaramakrishnan et al. | Feb 2002 | A1 |
| 20020018965 | Vahedi et al. | Feb 2002 | A1 |
| 20020042205 | McMillin et al. | Apr 2002 | A1 |
| 20020100416 | Sun et al. | Aug 2002 | A1 |
| 20020108570 | Lindfors | Aug 2002 | A1 |
| 20020108933 | Hoffman et al. | Aug 2002 | A1 |
| 20020144657 | Chiang et al. | Oct 2002 | A1 |
| 20020144706 | Davis et al. | Oct 2002 | A1 |
| 20020160125 | Johnson et al. | Oct 2002 | A1 |
| 20020170598 | Girard et al. | Nov 2002 | A1 |
| 20020173160 | Keil et al. | Nov 2002 | A1 |
| 20020192369 | Morimoto et al. | Dec 2002 | A1 |
| 20030003696 | Gelatos et al. | Jan 2003 | A1 |
| 20030019580 | Strang | Jan 2003 | A1 |
| 20030070620 | Cooperberg et al. | Apr 2003 | A1 |
| 20030094903 | Tao et al. | May 2003 | A1 |
| 20030226641 | Collins et al. | Dec 2003 | A1 |
| 20040112540 | Larson et al. | Jun 2004 | A1 |
| 20040129211 | Blonigan et al. | Jul 2004 | A1 |
| Number | Date | Country |
|---|---|---|
| 0 291 181 | Nov 1988 | EP |
| 1077476 | Feb 2001 | EP |
| 1 158 565 | Nov 2001 | EP |
| 1 300 877 | Apr 2003 | EP |
| 403-281780 | Dec 1991 | JP |
| 11016888 | Jan 1999 | JP |
| 2002280357 | Sep 2002 | JP |
| 0129879 | Apr 2001 | WO |
| 02080251 | Oct 2002 | WO |
| WO 02095519 | Nov 2002 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20050006346 A1 | Jan 2005 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 10642083 | Aug 2003 | US |
| Child | 10877222 | US | |
| Parent | 10318612 | Dec 2002 | US |
| Child | 10642083 | US |
