TREA

Semiconductor constructions

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Information

  • Patent Grant
  • 7825443
  • Patent Number
    7,825,443
  • Date Filed
    Monday, August 29, 2005
    19 years ago
  • Date Issued
    Tuesday, November 2, 2010
    14 years ago
Information
Abstract
In one aspect, the invention includes a semiconductor processing method. An antireflective material layer is formed over a substrate. At least a portion of the antireflective material layer is annealed at a temperature of greater than about 400° C. A layer of photoresist is formed over the annealed antireflective material layer. The layer of photoresist is patterned. A portion of the antireflective material layer unmasked by the patterned layer of photoresist is removed. In another aspect, the invention includes the following semiconductor processing. An antireflective material layer is formed over a substrate. The antireflective material layer is annealed at a temperature of greater than about 400° C. A layer of photoresist is formed over the annealed antireflective material layer. Portions of the layer of photoresist are exposed to radiation waves. Some of the radiation waves are absorbed by the antireflective material during the exposing.
Description
TECHNICAL FIELD

The invention pertains to semiconductor processing methods, such as, for example, methods of patterning photoresist in which an antireflective material is utilized to attenuate (for example, absorb) radiation.


BACKGROUND OF THE INVENTION

Semiconductor processing frequently involves providing a photoresist layer over a substrate. Portions of the photoresist layer are subsequently exposed to light through a masked light source. The mask contains clear and opaque features defining a pattern to be created in the photoresist layer. Regions of the photoresist layer which are exposed to light are made either soluble or insoluble in a solvent. If the exposed regions are soluble, a positive image of the mask is produced in the photoresist. The photoresist is therefore termed a positive photoresist. On the other hand, if the non-irradiated regions are dissolved by the solvent, a negative image results. Hence, the photoresist is referred to as a negative photoresist.


A difficulty that can occur when exposing photoresist to radiation is that waves of radiation can propagate through the photoresist to a layer beneath the photoresist and then be reflected back up through the photoresist to interact with other waves propagating through the photoresist. The reflected waves can constructively and/or destructively interfere with other waves propagating through the photoresist to create periodic variations of light intensity within the photoresist. Such variations of light intensity can cause the photoresist to receive non-uniform doses of energy throughout its thickness. The non-uniform dose can decrease the accuracy and precision with which a masked pattern is transferred to the photoresist. Also, the radiated waves reflected back from a non-flat surface underlying photoresist can enter portions of the photoresist that are not supposed to be exposed. Accordingly, it is desired to develop methods which suppress radiation waves from being reflected by layers beneath a photoresist layer.


A method which has been used with some success to suppress reflected waves is to form an antireflective material beneath a photoresist layer. Antireflective materials can, for example, comprise materials which absorb radiation, and which therefore quench reflection of the radiation.


Antireflective materials absorb various wavelengths of radiation with varying effectiveness. The wavelengths absorbed, and the effectiveness with which they are absorbed, vary depending on the materials utilized. The number of materials available for use as antireflective materials is limited. Accordingly, it is desired to develop alternative methods of varying the wavelengths absorbed, and effectiveness with which the wavelengths are absorbed, for antireflective materials.


SUMMARY OF THE INVENTION

In one aspect, the invention includes a semiconductor processing method wherein an antireflective material layer is formed over a substrate. At least a portion of the antireflective material layer is annealed at a temperature of greater than about 400° C. A layer of photoresist is formed over the annealed antireflective material layer. The layer of photoresist is patterned. A portion of the antireflective material layer unmasked by the patterned layer of photoresist is removed.


In another aspect, the invention includes a semiconductor processing method wherein an antireflective material layer is formed over a substrate. The antireflective material layer is annealed at a temperature of greater than about 400° C. A layer of photoresist is formed over the annealed antireflective material layer. Portions of the layer of photoresist are exposed to radiation waves, some of the radiation waves are attenuated by the antireflective material as the portions are exposed.


In yet another aspect, the invention includes a semiconductor processing method wherein a solid antireflective material layer is formed over a substrate. Optical properties of the antireflective material layer are altered. After altering the optical properties, a layer of photoresist is formed over the antireflective material layer. Portions of the layer of photoresist are exposed to radiation waves. Some of the radiation waves are absorbed by the antireflective material.





BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below with reference to the following accompanying drawings.



FIG. 1 is a fragmentary, diagrammatic, cross-sectional view of a semiconductor wafer fragment at a preliminary processing step of a method of the present invention.



FIG. 2 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that shown in FIG. 1.



FIG. 3 is a view of the FIG. 1 wafer fragment at a processing step subsequent to that shown in FIG. 2.



FIG. 4 is a second embodiment of a fragmentary, diagrammatic, cross-sectional view of a semiconductor wafer fragment at a preliminary processing step of a method of the present invention.



FIG. 5 is a third embodiment of a fragmentary, diagrammatic, cross-sectional view of a semiconductor wafer fragment at a preliminary processing step of a method of the present invention.





DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of the constitutional purposes of the U.S. Patent Laws “to promote the progress of science and useful arts” (Article 1, Section 8).


A method of the present invention is described with reference to FIGS. 1-3. Referring to FIG. 1, a semiconductor wafer fragment 10 is illustrated at a preliminary processing step. Wafer fragment 10 comprises a substrate 12, an overlying antireflective material layer 14, and a photoresist layer 16 over the antireflective material layer 14. The substrate can comprise, for example, a monocrystalline silicon wafer lightly doped with a conductivity-enhancing dopant. To aid in interpretation of this disclosure and the claims that follow, the term “semiconductive substrate” is defined to mean any construction comprising semiconductive material, including, but not limited to, bulk semiconductive materials such as a semiconductive wafer (either alone or in assemblies comprising other materials thereon), and semiconductive material layers (either alone or in assemblies comprising other materials). The term “substrate” refers to any supporting structure, including, but not limited to, the semiconductive substrates described above.


The antireflective material layer 14 can comprise an inorganic material, such as, for example, a material comprising from about 5% to about 37% (by atomic concentration) oxygen, about 10% to about 35% (by atomic concentration) nitrogen, from about 50% to about 65% (by atomic concentration) silicon, and hydrogen. A specific example inorganic material comprises about 10% (by atomic concentration) nitrogen, about 25% (by atomic concentration) oxygen and about 65% (by atomic concentration) silicon. Antireflective coating layer 14 can, for example, consist of a single substantially homogeneous layer of the above-described inorganic material.


As another example, antireflective coating layer 14 can comprise a stack of materials, with at least one of the materials in the stack being configured to attenuate radiation that passes through the photoresist. The attenuation can encompass either total or partial absorption of such radiation. If the attenuation encompasses only partial absorption, then preferably the radiation that is not absorbed will be reflected at an appropriate wavelength and phase such that it is cancelled by other radiation passing through the stack. In exemplary configurations of an antireflective layer comprising a stack of materials, FIGS. 4 and 5 illustrate the layer 14 comprises a material 14a comprising from about 5% to about 37% (by atomic concentration) oxygen, about 10% to about 35% (by atomic concentration) nitrogen, from about 50% to about 65% (by atomic concentration) silicon, and hydrogen at the bottom of the stack. The remainder of the stack comprises one or more layers, 14b and 14c (FIG. 5) respectively, that are fully or partially transmissive of the radiation. Such layers (14b and 14c) can comprise, for example, silicon dioxide.


Photoresist layer 16 can comprise either a negative photoresist or a positive photoresist.


In accordance with the present invention, antireflective material layer 14 is applied over substrate 12 and at least a portion of layer 14 is annealed at a temperature greater than about 400° C. (preferably greater than 400° C.) prior to formation of photoresist layer 16. If the antireflective material includes a portion comprising the above-discussed inorganic materials comprising nitrogen, oxygen, hydrogen and silicon, such portion can be applied by chemical vapor deposition at a temperature of from about 250° C. to about 400°. The portion is then preferably annealed at a temperature of from about 800° C. to about 1050° C., more preferably from about 800° C. to about 900° C., and most preferably about 850° C. During the anneal, the antireflective material layer 14 is preferably exposed to a nitrogen-containing atmosphere, such as an atmosphere comprising N2 and Ar. The atmosphere can, for example, consist essentially of N2.


An anneal of an antireflective material layer at a temperature of greater than about 400° C. has been found to alter optical properties of the antireflective material layer to make the antireflective material layer more absorptive to radiation. Such anneal is particularly beneficial for a portion of an antireflective material layer comprising oxygen, nitrogen, silicon, and hydrogen. Specifically, the anneal has been found to influence a refractive index coefficient (n) of the antireflective material layer and an extinction coefficient (energy absorption coefficient) (k) of the antireflective material layer. For instance, it has been found that an anneal at greater than about 400° C. of a hydrogenated material comprising about 10% (by atomic concentration) nitrogen, about 25% (by atomic concentration) oxygen and about 65% (by atomic concentration) silicon will alter the “n” and “k” of the material exposed to 248 nanometer wavelength light from 2.12 and 1.19, respectively, to 1.89 and 1.41, respectively. Also, the anneal will alter the “n” and “k” of such material when exposed to 365 nanometer wavelength light from 2.67 and 0.59, respectively, to 2.89 and 1.11, respectively.


After the anneal of at least a portion of antireflective material layer 14, photoresist layer 16 is formed over antireflective layer 14. Photoresist layer 16 can be formed by conventional methods. An example method includes spinning a photoresist liquid over layer 14 and subsequently volatilizing solids from the layer to form a solid photoresist layer 16.


Referring to FIG. 2, photoresist layer 16 is patterned by exposing the layer to a patterned beam of radiation. Such patterning can comprise conventional methods such as the negative photoresist processing or positive photoresist processing described in the “Background” section of this disclosure. Portions of photoresist layer 16 that are exposed to the radiation will behave differently in a solvent than will portions unexposed to radiation. Either the portion exposed to radiation or the portion unexposed to radiation is removed from over substrate 12 to leave the other of the portions exposed to radiation or unexposed to radiation remaining over substrate 12. Whether it is the portion that is exposed to radiation that is removed or the portion that is unexposed to radiation that is removed will depend on whether photoresist layer 16 comprises a negative or positive photoresist. The removal of a portion of photoresist layer 16 forms an opening 18 through photoresist layer 16. After formation of opening 18, photoresist layer 16 becomes a patterned mask. A portion of antireflective material layer 14 is covered by the patterned mask 16, and a portion is exposed through opening 18.


During the exposure of photoresist layer 16 to radiation, some of the radiation penetrates through layer 16 and into antireflective material layer 14. Antireflective material layer 14 attenuates, and preferably absorbs such penetrating radiation waves.


Referring to FIG. 3, opening 18 is extended through antireflective material layer 14 and into substrate 12. Opening 18 can be extended by conventional methods, such as, for example, a dry plasma etch or a wet etch.


In the shown embodiment, photoresist layer 16 is against antireflective material layer 14. It is to be understood that in other embodiments of the invention, which are not shown, intervening layers can be formed between photoresist layer 16 and antireflective material layer 14. If such intervening layers are at least partially transparent to the radiation utilized to pattern photoresist layer 16, the radiation will penetrate to antireflective material layer 14 and be absorbed by material layer 14 during exposure of photoresist layer 16 to the radiation. It is also to be understood that if such intervening layers are present, a pattern of layer 16 could be transferred to the intervening layers without extending the pattern to layer 14. Thus, the invention encompasses embodiments in which antireflective material layer 14 is not etched.


In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.

Claims
  • 1. A semiconductor construction comprising a substrate having a stack of layers thereover, at least one layer of the stack both contacting the substrate and comprising hydrogenated material, and another layer of the stack comprising silicon dioxide, the hydrogenated material comprising silicon, wherein a refractive index coefficient of at least a portion of the material when exposed to 248 nm wavelength light is less than or equal to 1.89.
  • 2. The construction of claim 1 wherein the material is configured to attenuate radiation.
  • 3. The construction of claim 1 wherein an extinction coefficient of at least a portion of the material when exposed to 248 nm wavelength light is less than or equal to 1.41.
  • 4. The construction of claim 1 further comprising photoresist over the stack.
  • 5. The construction of claim 4 wherein the photoresist comprises positive resist.
  • 6. The construction of claim 4 wherein the photoresist physically contacts the stack.
  • 7. The construction of claim 1 wherein the one layer of the stack further comprises both oxygen and nitrogen.
  • 8. The construction of claim 1 wherein the one layer of the stack further comprises from about 5% to about 37% oxygen.
  • 9. The construction of claim 1 wherein the one layer of the stack further comprises from about 10% to about 35% nitrogen.
  • 10. The construction of claim 1 wherein the one layer of the stack further comprises from about 50% to about 65% silicon.
CROSS REFERENCE TO RELATED APPLICATION

This patent is a divisional application of U.S. patent application Ser. No. 10/277,437, filed Oct. 21, 2002 now abandoned, entitled “Semiconductor Processing Methods”, which is a continuation application of U.S. patent application Ser. No. 09/030,618 filed Feb. 25, 1998, entitled “Semiconductor Processing Methods”, now U.S. Pat. No. 6,274,292, issued Aug. 14, 2001; the entirety of all of which are incorporated by reference herein.

US Referenced Citations (236)
Number Name Date Kind
4158717 Nelson Jun 1979 A
4444617 Whitcomb Apr 1984 A
4474975 Clemons et al. Oct 1984 A
4523214 Hirose et al. Jun 1985 A
4552783 Stoll et al. Nov 1985 A
4562091 Sachdev et al. Dec 1985 A
4592129 Legge Jun 1986 A
4600671 Saitoh et al. Jul 1986 A
4648904 DePasquale et al. Mar 1987 A
4695859 Guha et al. Sep 1987 A
4702936 Maeda et al. Oct 1987 A
4755478 Abernathey et al. Jul 1988 A
4764247 Leveriza et al. Aug 1988 A
4805683 Magdo et al. Feb 1989 A
4833096 Huang et al. May 1989 A
4863755 Hess et al. Sep 1989 A
4870470 Bass, Jr. et al. Sep 1989 A
4907064 Yamazaki et al. Mar 1990 A
4910160 Jennings et al. Mar 1990 A
4940509 Tso et al. Jul 1990 A
4954867 Hosaka Sep 1990 A
4971655 Stefano et al. Nov 1990 A
4992306 Hochberg et al. Feb 1991 A
5034348 Hartswick et al. Jul 1991 A
5036383 Mori Jul 1991 A
5061509 Naito et al. Oct 1991 A
5140390 Li et al. Aug 1992 A
5219613 Fabry et al. Jun 1993 A
5234869 Mikata et al. Aug 1993 A
5244537 Ohnstein Sep 1993 A
5258608 Uchiya Nov 1993 A
5260600 Harada Nov 1993 A
5270267 Ouellet Dec 1993 A
5276347 Wei et al. Jan 1994 A
5285017 Gardner Feb 1994 A
5286661 de Fresart et al. Feb 1994 A
5302366 Schuette et al. Apr 1994 A
5312768 Gonzalez May 1994 A
5314724 Tsukune et al. May 1994 A
5340621 Matsumoto et al. Aug 1994 A
5356515 Tahara et al. Oct 1994 A
5376591 Maeda et al. Dec 1994 A
5405489 Kim et al. Apr 1995 A
5413963 Yen et al. May 1995 A
5429987 Allen Jul 1995 A
5439838 Yang Aug 1995 A
5441797 Hogan et al. Aug 1995 A
5461003 Havemann et al. Oct 1995 A
5470772 Woo Nov 1995 A
5472827 Ogawa et al. Dec 1995 A
5472829 Ogawa Dec 1995 A
5482894 Havemann Jan 1996 A
5498555 Lin Mar 1996 A
5536857 Narula et al. Jul 1996 A
5541445 Qullet Jul 1996 A
5543654 Dennen Aug 1996 A
5550008 Tomo et al. Aug 1996 A
5554567 Wang Sep 1996 A
5591494 Sato et al. Jan 1997 A
5591566 Ogawa Jan 1997 A
5593741 Ikeda Jan 1997 A
5600165 Tsukamoto et al. Feb 1997 A
5639687 Roman Jun 1997 A
5641607 Ogawa et al. Jun 1997 A
5648202 Ogawa et al. Jul 1997 A
5652187 Kim et al. Jul 1997 A
5656330 Niiyama et al. Aug 1997 A
5656337 Park et al. Aug 1997 A
5661093 Ravi et al. Aug 1997 A
5667015 Harestad et al. Sep 1997 A
5670297 Ogawa et al. Sep 1997 A
5674356 Nagayama Oct 1997 A
5677015 Hasegawa Oct 1997 A
5677111 Ogawa Oct 1997 A
5691212 Tsai et al. Nov 1997 A
5698352 Ogawa et al. Dec 1997 A
5709741 Akamatsu et al. Jan 1998 A
5710067 Foote et al. Jan 1998 A
5711987 Bearinger et al. Jan 1998 A
5731242 Parat et al. Mar 1998 A
5741721 Stevens Apr 1998 A
5744399 Rostoker Apr 1998 A
5747388 Kusters May 1998 A
5750442 Juengling May 1998 A
5753320 Mikoshiba et al. May 1998 A
5759746 Azuma et al. Jun 1998 A
5759755 Park et al. Jun 1998 A
5783493 Yeh et al. Jul 1998 A
5786039 Brouquet Jul 1998 A
5789819 Gnade et al. Aug 1998 A
5792689 Yang et al. Aug 1998 A
5796151 Hsu et al. Aug 1998 A
5800877 Maeda et al. Sep 1998 A
5801399 Hattori et al. Sep 1998 A
5807660 Lin et al. Sep 1998 A
5817549 Yamazaki et al. Oct 1998 A
5831321 Nagayama Nov 1998 A
5838052 McTeer Nov 1998 A
5840610 Gilmer et al. Nov 1998 A
5858880 Dobson et al. Jan 1999 A
5872035 Kim et al. Feb 1999 A
5872385 Taft et al. Feb 1999 A
5874367 Dobson Feb 1999 A
5883011 Lin et al. Mar 1999 A
5883014 Chen Mar 1999 A
5933721 Hause et al. Aug 1999 A
5948482 Brinker et al. Sep 1999 A
5960289 Tsui et al. Sep 1999 A
5962581 Hayase et al. Oct 1999 A
5968324 Cheung et al. Oct 1999 A
5968611 Kaloyeros et al. Oct 1999 A
5981368 Gardner et al. Nov 1999 A
5985519 Kakamu et al. Nov 1999 A
5986318 Kim et al. Nov 1999 A
5994217 Ng Nov 1999 A
5994730 Shrivastava et al. Nov 1999 A
6001741 Alers Dec 1999 A
6001747 Annapragada Dec 1999 A
6004850 Lucas et al. Dec 1999 A
6005277 Liu et al. Dec 1999 A
6008121 Yang et al. Dec 1999 A
6008124 Sekiguchi et al. Dec 1999 A
6017614 Tsai et al. Jan 2000 A
6017779 Miyasaka Jan 2000 A
6020243 Wallace et al. Feb 2000 A
6022404 Ettlinger et al. Feb 2000 A
6028015 Wang et al. Feb 2000 A
6030901 Hopper et al. Feb 2000 A
6037228 Hsu Mar 2000 A
6040619 Wang et al. Mar 2000 A
6054379 Yau et al. Apr 2000 A
6057217 Uwasawa May 2000 A
6057587 Ghandehari et al. May 2000 A
6060765 Maeda May 2000 A
6060766 Mehta et al. May 2000 A
6071799 Park et al. Jun 2000 A
6072227 Yau et al. Jun 2000 A
6080529 Ye et al. Jun 2000 A
6083852 Cheung et al. Jul 2000 A
6087064 Lin et al. Jul 2000 A
6087267 Dockrey et al. Jul 2000 A
6096656 Matzke et al. Aug 2000 A
6114255 Juengling Sep 2000 A
6114736 Balasubramanyam et al. Sep 2000 A
6118163 Gardner et al. Sep 2000 A
6121133 Iyer et al. Sep 2000 A
6124641 Matsuura Sep 2000 A
6130168 Chu et al. Oct 2000 A
6133096 Su et al. Oct 2000 A
6133613 Yao et al. Oct 2000 A
6133618 Steiner Oct 2000 A
6136636 Wu Oct 2000 A
6140151 Akram Oct 2000 A
6140677 Gardner et al. Oct 2000 A
6143670 Cheng et al. Nov 2000 A
6153504 Shields et al. Nov 2000 A
6156485 Tang et al. Dec 2000 A
6156674 Li et al. Dec 2000 A
6159804 Gardner et al. Dec 2000 A
6159871 Loboda et al. Dec 2000 A
6184151 Adair et al. Feb 2001 B1
6184158 Shufflebotham et al. Feb 2001 B1
6187657 Xiang et al. Feb 2001 B1
6187694 Cheng et al. Feb 2001 B1
6198144 Pan et al. Mar 2001 B1
6200835 Manning Mar 2001 B1
6200863 Xiang et al. Mar 2001 B1
6204168 Naik et al. Mar 2001 B1
6208004 Cunningham Mar 2001 B1
6209484 Huang et al. Apr 2001 B1
6218292 Foote Apr 2001 B1
6225217 Usami et al. May 2001 B1
6235568 Murthy et al. May 2001 B1
6235591 Balasubramanian et al. May 2001 B1
6238976 Noble et al. May 2001 B1
6268282 Sandhu et al. Jul 2001 B1
6274292 Holscher et al. Aug 2001 B1
6281100 Yin et al. Aug 2001 B1
6284677 Hsiao et al. Sep 2001 B1
6323101 Li et al. Nov 2001 B1
6331493 Sharan Dec 2001 B1
6348407 Gupta et al. Feb 2002 B1
6373114 Jeng et al. Apr 2002 B1
6383951 Li May 2002 B1
6403464 Chang Jun 2002 B1
6429115 Tsai et al. Aug 2002 B1
6432791 Hutter et al. Aug 2002 B1
6435943 Chang et al. Aug 2002 B1
6436808 Ngo et al. Aug 2002 B1
6440860 DeBoer et al. Aug 2002 B1
6444593 Ngo et al. Sep 2002 B1
6451504 Rolfson et al. Sep 2002 B2
6465372 Xia et al. Oct 2002 B1
6486057 Yeh et al. Nov 2002 B1
6486061 Xia et al. Nov 2002 B1
6492688 Ilg Dec 2002 B1
6498084 Bergemont Dec 2002 B2
6503818 Jang Jan 2003 B1
6518122 Chan et al. Feb 2003 B1
6528432 Ngo et al. Mar 2003 B1
6589890 Cohen et al. Jul 2003 B2
6627532 Gaillard et al. Sep 2003 B1
6627535 MacNeil et al. Sep 2003 B2
6632478 Gaillard et al. Oct 2003 B2
6632712 Ang et al. Oct 2003 B1
6638875 Han et al. Oct 2003 B2
6653247 MacNeil Nov 2003 B2
6716725 Ishikawa Apr 2004 B1
6720247 Kirkpatrick et al. Apr 2004 B2
6723631 Noguchi et al. Apr 2004 B2
6727173 Sandhu et al. Apr 2004 B2
6790778 Cheng et al. Sep 2004 B1
6849561 Goundar Feb 2005 B1
20010003064 Ohto Jun 2001 A1
20010019868 Gonzalez et al. Sep 2001 A1
20010038919 Berry, III et al. Nov 2001 A1
20020016085 Huang et al. Feb 2002 A1
20020033486 Kim et al. Mar 2002 A1
20020055275 MacNeil May 2002 A1
20020081834 Daniels et al. Jun 2002 A1
20020098684 Li et al. Jul 2002 A1
20030013311 Chang et al. Jan 2003 A1
20030077916 Xu et al. Apr 2003 A1
20030164354 Hsieh et al. Sep 2003 A1
20030173671 Hironaga et al. Sep 2003 A1
20030201465 Ryuzaki et al. Oct 2003 A1
20030207594 Catabay et al. Nov 2003 A1
20030235979 Yuasa Dec 2003 A1
20040053459 MacNeil Mar 2004 A1
20040071878 Schuhmacher et al. Apr 2004 A1
20040126671 Smith et al. Jul 2004 A1
20040175933 Shishida et al. Sep 2004 A1
20050023691 Watanabe Feb 2005 A1
20050064698 Chang et al. Mar 2005 A1
20050191828 Al-Bayati et al. Sep 2005 A1
20070098890 Sasaki et al. May 2007 A1
Foreign Referenced Citations (26)
Number Date Country
0 464515 Jan 1992 EP
0 471 185 Feb 1992 EP
0464515 Aug 1992 EP
0 588 087 Mar 1994 EP
0 588 087 Mar 1994 EP
0 771886 May 1997 EP
0771886 Jul 1997 EP
0 942330 Sep 1999 EP
1 172 845 Jan 2002 EP
593727 Oct 1947 GB
63-157443 Jun 1988 JP
63316476 Dec 1988 JP
06-196400 Jul 1994 JP
6232113 Aug 1994 JP
6-244172 Sep 1994 JP
7201716 Aug 1995 JP
08045926 Feb 1996 JP
8046186 Feb 1996 JP
8046188 Feb 1996 JP
8051058 Feb 1996 JP
8078322 Mar 1996 JP
408213386 Aug 1996 JP
9-50993 Feb 1997 JP
10-163083 Jun 1998 JP
47112 Jan 2002 TW
471112 Jan 2002 TW
Related Publications (1)
Number Date Country
20060220186 A1 Oct 2006 US
Divisions (1)
Number Date Country
Parent 10277437 Oct 2002 US
Child 11214998 US
Continuations (1)
Number Date Country
Parent 09030618 Feb 1998 US
Child 10277437 US