The present invention is directed to structures utilizing metal films for bonding purposes, and more particularly, to structures utilizing metal films which adhere to the underlying substrate and provide a diffusion barrier.
When joined components are expected to be exposed to relatively high temperatures, the options for joining the components are limited. Joining methods such as welding, brazing, active metal brazing and mechanical fastening can be utilized to join components for service in high temperature environments. However, these joining techniques can be difficult to implement, may not be universally applicable to all substrates and materials, and can be prone to brittle fracture. Joining techniques can become further limited when it is desired to join disparate materials, such as ceramic to silicon.
In some cases a binary or eutectic alloy, such as a gold/nickel eutectic braze, can be utilized as a bonding layer to couple the components together. Depending upon the particular composition, binary or eutectic alloys are relatively heat resistant. However, the use of a binary or eutectic alloy requires metal films (also known as bonding films, metal coatings or metallization) on the associated component(s) to allow the binary or eutectic alloys to adhere to the associated component and to block diffusion of undesired materials therethrough. Accordingly, there is a need for metal films that can be used in binary or eutectic alloy joining procedures that can adhere well to the associated component, resist significant diffusion therethrough and be thermodynamically stable at elevated temperatures. There is also a need for metal films which are robust and which are electrically conductive so that the films can serve as an electrical contact layer.
In one embodiment, the present invention provides a component including a bonding film or metallization. In various embodiments, this metallization adheres well to the underlying substrate at elevated temperatures, resists significant diffusion, and is thermodynamically stable at elevated temperatures.
In another embodiment, the invention provides a component suitable for bonding including a substrate and a metallization layer wherein:
the substrate is selected from the group consisting of semiconductors (e.g., silicon, silicon carbide or polysilicon), ceramics (e.g., aluminum nitride, sapphire or silicon nitride), glasses, nonmetallic materials, or combinations of these materials; and
the metallization layer includes:
an adhesion layer selected from the group consisting of tantalum, chromium, zirconium, and hafnium and compounds thereof, e.g., compounds that are the reaction product of the substrate and one or more of the aforesaid metals;
a first diffusion blocking layer of a compound selected from the group consisting of tantalum silicide, tantalum carbide and tungsten nitride; and
a second diffusion blocking layer of platinum.
In a more particular embodiment, the invention is a structure including a component and a metallization film on the component. The metallization film includes a tantalum layer located on the component, a tantalum silicide layer located on the tantalum layer, and a platinum silicide layer located on the tantalum silicide layer.
In another embodiment, the metallization film is characterized in that it has an adhesive strength to silicon, after annealing, of at least about 100 MPa after exposure to a temperature of about 600° C. for about 30 minutes, and the metallization film remains structurally intact after exposure to a temperature of about 600° C. for about 1000 hours.
Another embodiment of the invention is a bonding film or metallization comprising the adhesion and diffusion blocking layers described herein.
The substrate 10 includes a metal film or metallization layer 12 located thereon. It should be understood that when a layer or component is referred to as being located “on” or “above” another layer, component or substrate, (such as the metal film 12 located on the substrate 10) this layer or component may not necessarily be located directly on the other layer, component or substrate, and intervening layers, components, or materials could be present. Furthermore, when a layer or component is referred to as being located “on” or “above” another layer, component or substrate, that layer or component may either fully or partially cover the other layer, component or substrate.
In the embodiment shown in
Tantalum is one example of the adhesion material 14 because tantalum adheres well to a variety of materials. However, besides tantalum, various other materials such as chromium, zirconium, hafnium, or any element which reacts favorably with the substrate 10 to form compounds which bond strongly to the substrate may be utilized as the adhesion layer 14. In particular, in one embodiment, the adhesion layer 14 preferably has an adhesion strength to the substrate 10 of at least about 10 MPa, or more preferably at least about 50 MPa, or most preferably at least about 100 MPa as measured by a mechanical shear test. For example adhesion strength can be determined by a die shear strength test specified in Military Standard 883, Procedure 2019.5, or methods similar thereto.
In one embodiment, the adhesion layer 14 has a relatively high post-annealing adhesive strength to the substrate 10 at elevated temperatures, for example at temperatures above about 600° C. Thus, in one embodiment, the adhesion layer 14 has a post-annealing adhesion strength to silicon of at least about 10 MPa, or more preferably about 50 MPa, or most preferably at least about 100 MPa, at temperatures of about 600° C. as measured by a mechanical shear test.
The adhesion layer 14 has a variety of thicknesses, and can be deposited in a variety of manners. However, the adhesion layer 14 should have sufficient thickness to ensure proper adhesion to the substrate 10, but should not be so thick so as to add significant bulk to the metallization layer 12. The adhesion layer 14 preferably may be initially deposited to a thickness of between about 100 Angstroms and about 10,000 Angstroms, or more preferably about 200 Angstroms and about 1,000 Angstroms, and most preferably about 500 Angstroms (it should be understood that the thickness of the various layers shown in the drawings are not necessarily to scale). The adhesion layer 14 can be deposited by plasma enhanced physical vapor deposition (also known as plasma sputtering) or any other suitable deposition technique known in the art.
In the preferred embodiment, when the adhesion layer 14 is tantalum, the presence of oxygen at the interface of the adhesion layer 14 and a silicon substrate 10 can inhibit silicide formation which, as will be discussed below, is desired for its diffusion blocking properties. The presence of oxygen at the interface of the adhesion layer 14 and the substrate 10 can also cause adverse metallurgical transformations in the adhesion layer 14 to thereby create a highly stressed (i.e., weak) adhesion layer 14.
Accordingly, in one embodiment, prior to depositing the adhesion layer 14 on the substrate, the upper surface of the substrate 10 is cleaned to remove oxides. This cleaning step may involve the removal of oxides through plasma sputter etching or a liquid HF (hydrofluoric acid) solution. However, plasma sputter etching can cause excessive heating and surface roughening, and the HF wet etch process requires a water rinse which can cause re-oxidation of the substrate.
Therefore, a most preferred method to remove any oxides on the surface of the substrate 10 is to use a dry HF vapor cleaning process. The dry HF vapor cleaning does not require water rinsing and thereby provides a fully deoxidized substrate 10. The conditions for wet and dry HF etching/cleaning processes are well known in the art. The adhesion layer 14 should be deposited on the substrate 10 shortly after the cleaning step to ensure deposition thereon before oxides have the opportunity to redevelop on the substrate 10 (i.e. due to oxidizing chemical reactions with oxygen in the surrounding environment).
Outwardly diffusing materials, e.g., silicon of the substrate 10, may react with the materials of the metallization film 12 which can weaken the metallization layer 12. Thus, the second layer 16 is made of a material or materials which blocks the outward diffusion of the substrate material 10. Although the second 16 and third 18 layers are designated as inward and outward diffusion blocking layers, respectively, it should be understood that the second 16 and third 18 layers may not, by themselves, necessarily block diffusion in the desired manner. Instead, each of the layers 16, 18 may include or contribute a material which reacts to form a diffusion blocking layer upon sintering, annealing, chemical reactions, etc. of the film 12, as will be discussed in greater detail below.
The second layer 16 can be made of any of a wide variety of materials depending upon the materials of the substrate 10 (the outward diffusion of which is desired to be blocked). In one embodiment, the second layer 16 is tantalum silicide although a variety of other materials including but not limited to tantalum carbide and tungsten nitride may be utilized. The second layer 16 should have a thickness sufficient to prevent outward diffusion of the substrate material 10, or to contribute sufficient materials to form a sufficient outward diffusion barrier layer after annealing. The second layer 16 preferably is initially deposited to a thickness of between about 100 Angstroms and about 10,000 Angstroms, and more preferably between about 1,000 Angstroms and about 10,000 Angstroms, and most preferably, about 5,000 Angstroms. The second layer 16 is deposited by plasma sputtering, or any other suitable deposition technique known in the art.
When the second layer 16 is made of compounds (for example, tantalum silicide) the tantalum silicide may be deposited directly in its form as tantalum silicide. Alternately, layers of tantalum and layers of silicon may be deposited to subsequently react and form tantalum silicide. In this case alternating, thin (i.e. 5 to 20 Angstroms) discrete layers of the two basic materials (i.e., tantalum and silicon) are deposited on the adhesion layer 14 in a co-deposition process. The number of alternating layers is not critical provided that the total thickness of the composite layer is between about 100 and about 10,000 Angstroms as described above. After the alternating layers of tantalum and silicon are deposited, the alternating layers are exposed to elevated temperatures during an annealing step, which is discussed in greater detail below. During the subsequent annealing step (described below) the alternating layers of tantalum and silicon diffuse or react to form a single layer of tantalum silicide.
When using this method to deposit the tantalum silicide, the relative thickness of the deposited layers of tantalum and silicon during the co-deposition process controls the ratio of tantalum and silicon in the resultant tantalum silicide layer 16. Thus, the ability to control the relative thickness of the tantalum and silicon layers allows a silicon-rich or silicon-lean layer of tantalum silicide to be formed. For example, a relatively silicon-rich layer of tantalum silicide (i.e. tantalum silicide having an atomic composition of a few percentage points richer in silicon than stoichiometric tantalum silicide (TaSi2)) may be preferred as the outward diffusion barrier 16 to enhance diffusion resistance.
The third layer 18 is made of a material or materials that may block or limit inward diffusion of undesired elements, compounds or gases. For example, the third layer 18 can be made of materials which block the inward diffusion of gases such as nitrogen, oxygen or carbon dioxide in the surrounding environment, or which block the outward diffusion of solid elements or compounds located on the metallization layer 12. These undesired elements, compounds or gases can adversely react with the other materials of the metallization layer 12 or the materials of substrate 10. In particular, inward diffusion of oxygen or nitrogen creates oxides or nitrides in the metallization layer 12 or in the substrate 10 which can weaken the metallization film 12 or its adhesion to the substrate 10, or otherwise adversely affect the properties of the metallization film 12 or substrate 10.
The third layer 18 may be made of a variety of materials, depending upon the materials of the substrate 10 and the materials of the adhesion 14 and second layer 16, as well as the elements, compounds or gases which are desired to be blocked from diffusing inwardly. However, platinum is a preferred material for the third layer 18. The third layer 18 is preferably deposited to an initial thickness of between about 100 Angstroms and about 10,000 Angstroms, or more preferably, between about 1,000 Angstroms and 5,000 Angstroms, and most preferably about 3,000 Angstroms. The third layer 18 is deposited by plasma sputtering or other suitable deposition methods known to those skilled in the art.
In particular, when the substrate 10 is silicon and the first 14, second 16 and third 18 layers are tantalum, tantalum silicide and platinum, respectively, after annealing an inner tantalum silicide layer 20 is formed as a reaction product of the adhesion layer 14 and the substrate 10. The inner tantalum silicide layer 20 adheres well to the tantalum adhesion layer 14 and to the substrate 10, and therefore provides a high adhesion strength for the metallization layer 12. In addition, because tantalum silicide generally blocks the outward diffusion of many materials (including silicon), the inner tantalum silicide layer 20 also acts as an outward diffusion-blocking layer for a silicon substrate 10.
When the substrate 10 is aluminum nitride (instead of silicon), the layer 20 may be or include materials other than tantalum silicide, such as tantalum nitride, tantalum aluminide or ternary compounds of tantalum, aluminum, and nitrogen. When the substrate 10 is made of materials other than silicon or aluminum nitride, and tantalum is used as the adhesion layer 14, various other diffusion-blocking tantalum compounds are formed depending upon the material of the substrate.
As shown in
When the substrate of
The two step anneal process improves adhesion of the metallization layer 12 to the substrate 10 and in particular improves adhesion of the adhesion layer 14. In addition, because a significant portion of the two step anneal process occurs at a relatively low temperature (i.e., below 600° C.), diffusion of platinum or tantalum through the layer 10a and into the conductive layer 10b is reduced, thereby reducing electrical leakage issues. Thus, either the one-step or two-step anneal process outlined above (or various other annealing steps that accomplish the results outlined above) can be carried out on the metallization film 12 to provide the structures shown in
Both the first 25 and second 27 bonding materials may be deposited on the metallization layer 12 by plasma sputtering or other suitable deposition techniques known to those skilled in the art. Further, the first 25 and second 27 bonding materials can be deposited in a variety of thicknesses. However, the thickness of the bonding materials 25, 27 should be selected to provide the desired ratio between the first 25 and second 27 bonding materials in the end product bond. In addition, the bonding layer 24 can include a variety of materials, compounds, compositions and the like, beyond those disclosed above for the first 25 and second 27 bonding materials. Representative examples of materials of the bonding layer 24 includes InCuAu, AuNi, TiCuNi, AgCu, AgCuZn, InCuAg, and AgCuSn.
In the illustrated embodiment the bonding layer 24 includes a capping layer 29 located on the first bonding material 25. The capping layer 29 caps and protects the first bonding material 25 to prevent oxidation of the first bonding material 25. The capping layer 29 can be any of a wide variety of materials which resist oxidation, such as gold. The capping layer 29 is preferably the same material as the second bonding layer 27 so that the capping layer 29 participates in the eutectic joining process. The capping layer 29 is quite thin, preferably having a thickness of about 1000 Angstroms or less.
For the description below, it will be assumed that the first bonding materials 25, 25′ are germanium, and that the second bonding materials 27, 27′ and capping materials 29, 29′ are gold to allow discussion of the specific properties of the gold/germanium eutectic alloy. However, this discussion is for illustrative purposes and it should be understood that various other materials may be utilized as the first bonding materials 25, 25′, second bonding materials, 27, 27′ and capping materials 29, 29′.
The substrates 10, 10′ are next joined or bonded in a transient liquid phase bonding process which is well known in the art, but is outlined briefly below. To commence the transient liquid phase bonding a light pressure (e.g. a few pounds) is applied to press the substrates 10, 10′ and bonding layers 24, 24′ together (
In the illustrative example the bonding layers 24, 24′ are exposed to a temperature of about 450° C. However, the actual bonding temperatures will depend upon the diffusion rate of the bonding materials 25, 25′, 27, 27′, the thickness of the bonding materials and the time available to complete the diffusion such that a uniform solid solution of the bonding alloy is achieved.
Once the materials at the gold/germanium interfaces reach the eutectic temperature (i.e., 361° C.), zones of melted or liquid materials 31 are formed at each interface (see
As the bonding layers 24, 24′ continue to heat up and approach the ambient temperature (i.e., 450° in the illustrated example), the liquid zones 31 continue to grow and expand until all the material of the germanium layers 25, 25′ melt and have been dissolved into the liquid zones 31. The separate liquid zones 31 of
Next, the materials of the gold layers 27, 27′ adjacent to the liquid zone 31 continue to liquefy as the surrounding materials approach the ambient temperature. As additional gold is melted and added to the liquid zone 31, the germanium in the liquid zone 31 is diluted and the percentage of germanium in the liquid zone 31 is thereby reduced. Thus, the composition of the liquid zone 31 moves up and to the left of point A along the liquidus line 37 of
Once the composition of the liquid zone 31 reaches point B, the germanium in the liquid zone 31 begins diffusing into the remaining solid gold layer 27, 27′ at the interface 33 of the liquid zone 31 and the gold layers 27, 27′. As this occurs, the concentration of germanium in the liquid zone 31 adjacent to the interface 33 drops. Once the percentage of germanium at the interface 33 drops sufficiently low (i.e., about 3 atomic percent germanium or less), the liquid zone 31 at the interface 33 forms into a solid solution phase 35 (see
The ambient temperature continues to be held at 450° C. and remaining germanium in the liquid zone 31 continues to diffuse outwardly, through the newly-formed solids 35 and into the predominantly gold layers 27, 27′. As the germanium in the liquid zone 31 continues to diffuse outwardly, more germanium-poor liquids at the interface 33 of the liquid zone 31 and the solids 35 are created and ultimately form into solids 35. In this manner the solids 35 grow inwardly until the entire liquid zone 31 is consumed (
The solid 35 formed after solid state diffusion is a gold/germanium alloy or solid solution alloy having a composition of about 3 atomic percent germanium. However, the amount of available germanium may be restricted and/or scavenged (with a germanium scavenging material such as platinum, nickel and chromium) so that the resultant solid has a composition of less than 3 atomic percent germanium (e.g., as low as about 0.5 atomic percent germanium or even lower), which places the composition of the solid 35 to the left of point C of
The transient liquid phase bonding method described above allows the joining of two materials at a relatively low temperature (but above the eutectic temperature) and results in a bond having a relatively high melting temperature. The resultant bonding material 35 is a hypoeutectic gold-germanium solid alloy having a relatively high melting temperature. The solid bonding material 35 can also be a hypoeutectic gold-silicon solid alloy or a hypoeutectic gold-tin solid alloy depending upon the starting materials for the bonding layers 24, 24′.
As described above the metallization film 12 includes the inward diffusion blocking layer 22 which blocks inward diffusion of materials. In particular, during the bonding process discussed above and shown in
For example, when the structure of
Similarly, layers 20 and/or 14 and/or 16 block outward diffusion of materials of the substrate 10 during bonding or exposure to elevated temperatures. In particular, when the structure of
In addition, the metallization layer 12 remains stable at elevated temperatures, for example during the elevated temperature of the bonding process. The metallization layer 12 of
The metallization layer 12 can be used as a substrate for bonding a variety of components, substrates, or the like. In the example shown in
In order to deposit the first 14, second 16 and third 18 layers onto the circumferential outer surface 36, a cylindrical magnetron sputter deposition system may be utilized. In such a sputter system, the disk 30 is placed on a rotating fixture inside the sputter chamber of the cylindrical magnetron. The cylindrical magnetron deposits the first layer 14, the second layer 16 and the third layer 18 onto the outer surface 36 of the disk 30 in a direction normal to the outer surface 36. In this manner the cylindrical magnetron provides a sputtering flux that is normal to the curved surface 36 (i.e. the direction of flow of the metal atoms is normal to the outer surface 36). After deposition of the first 14, second 16 and third 18 layers, the layers 14, 16, 18 may be annealed to provide the layers 14, 16, 20, 22 (
The particular type of braze material, braze slurry, braze alloy or braze paste depends upon the type of materials of the disk 30 and the housing 40, but may take the form of a braze material pre-formed into the shape of a ring.
The braze material 44 may be deposited at room temperature and then exposed to an elevated temperature (i.e. a temperature of about 500° C.) suitable to melt the braze material 44. The melted braze material 44 (which acts as the bonding layer in the embodiment shown in
The disk 30 and housing 40 are sized to form a robust joint. In particular, upon heating (i.e. during the brazing process), the housing 40 expands to relatively loosely receive the disk 30 therein (shown in
Because the metallization layer 12 adheres well to the disk 30, forms diffusion blocking layers, and is thermodynamically stable to high temperatures, the metallization layer 12 can be useful in forming brazed joints as described above. In this embodiment, the housing 40 does not require a metallization layer because the housing 40 is made of metal. Thus, in addition for use in eutectic or binary bonding or the like (as described above and shown in
When bonding the structures of
For illustrative purposes and to more easily show subsequent bonding steps,
As shown in
After the bonding contacts 52, 52′, 54, 54′ are formed, the wafer 50 is located on top of the disk 30 so that the bonding contacts 52, 54 engage each other (
Each layer 14, 16, 22 of the metallization layers 12 is preferably made of an electrically conductive material. For example, as outlined above the metallization layer 12 may include tantalum, tantalum silicide, platinum and platinum silicide, all of which are electrically conductive. In addition, the bonding layers 24, 24′ can be made of metals or other electrically conductive materials (i.e. gold and germanium). In this manner, the bonding contacts 52, 52′, 54, 54′ also serve to electrically couple the disk 30 and wafer 50. In particular, various electrical bond pads, output pads, metallic contacts and the like of the disk 30 and wafer 50 can be electrically coupled together by the bonding contacts. In this manner, the bonding contacts 52, 52′, 54, 54′ can serve the dual function of bonding the two components 30, 50 together as well as providing electrical contacts therebetween.
If desired either contact 54, 54′ may be located on or electrically coupled to a pin (not shown) embedded in the disk 30. The pin may be electrically coupled to an external device such as a processor (not shown) to thereby electrically couple the electronic component 55 to the external device. The lead 54′ thus provides a robust and high heat resistant electrical contact.
In one example, double side polished 100 mm diameter single-crystal silicon wafer having a thickness of about 400 microns is provided. The wafer is then cleaned using the well known RCA1 cleaning process which removes organic films and residue from the wafer using water, hydrogen peroxide and ammonium hydroxide. The silicon wafer is then exposed to HF vapors for one minute to further clean the wafer.
The cleaned silicon wafer is then directly inserted into a sputter deposition system, such as a Model 944 Sputter System sold by KDF Electronic Vacuum Services Inc. of Valley Cottage, N.Y., or a CMS-18 Sputter System sold by Kurt J. Lesker Co. of Clairton, Pa. The sputter chamber is then depressurized to a pressure of between about 5 and about 15 millitorr. The wafer is then sputter etched at a power of about 100 Watts for 5 minutes to remove any residual oxides. A tantalum adhesion layer is then deposited to a thickness of about 500 Angstroms. Next, a tantalum silicide outward diffusion blocking layer is deposited to a thickness of about 2,000 Angstroms. A platinum inward diffusion blocking layer is then deposited to a thickness of about 1,500 Angstroms.
The silicon wafer with tantalum, tantalum silicide and platinum is then removed from the sputter deposition system and placed in an oven for annealing. The wafer is then annealed at 450° C. for 1 hour, and then annealed at 600° C. for 1 hour, with both annealing steps taking place at a pressure of 10-5 Torr. The annealed wafer is then re-inserted into the sputter system and exposed to a sputter etch at a power 100 Watts for 5 minutes. A tantalum adhesion layer is deposited to a thickness of 500 Angstroms, after which the bonding materials are deposited thereon. The silicon wafer can then be bonded to another component by transient liquid phase bonding techniques.
Having described the invention in detail and by reference to the preferred embodiments, it will be apparent that modifications and variations thereof are possible without departing from the scope of the invention.
Number | Name | Date | Kind |
---|---|---|---|
3200490 | Clymer | Aug 1965 | A |
3396454 | Murdock et al. | Aug 1968 | A |
3619742 | Rud, Jr. | Nov 1971 | A |
3879746 | Fournier | Apr 1975 | A |
3935986 | Lattari et al. | Feb 1976 | A |
4215156 | Dalal et al. | Jul 1980 | A |
4233337 | Friedman et al. | Nov 1980 | A |
4330343 | Christou et al. | May 1982 | A |
4400869 | Wilner et al. | Aug 1983 | A |
4505027 | Schwabe et al. | Mar 1985 | A |
4545115 | Bauer et al. | Oct 1985 | A |
4637129 | Derkits, Jr. et al. | Jan 1987 | A |
4702941 | Mitchell et al. | Oct 1987 | A |
4722227 | Grob et al. | Feb 1988 | A |
4758534 | Derkits, Jr. et al. | Jul 1988 | A |
4777826 | Rud, Jr. et al. | Oct 1988 | A |
4910578 | Okamoto | Mar 1990 | A |
4912543 | Neppl et al. | Mar 1990 | A |
4939497 | Nishida et al. | Jul 1990 | A |
4960718 | Aina | Oct 1990 | A |
5038996 | Wilcox et al. | Aug 1991 | A |
5182218 | Fujihira | Jan 1993 | A |
5200349 | Yokoyama | Apr 1993 | A |
5285097 | Hirai | Feb 1994 | A |
5286671 | Kurtz et al. | Feb 1994 | A |
5346855 | Byrne et al. | Sep 1994 | A |
5369300 | Heideman et al. | Nov 1994 | A |
5374564 | Bruel | Dec 1994 | A |
5436491 | Hase et al. | Jul 1995 | A |
5457345 | Cook et al. | Oct 1995 | A |
5536967 | Yokoyama | Jul 1996 | A |
5559817 | Derkits, Jr. et al. | Sep 1996 | A |
5637905 | Carr et al. | Jun 1997 | A |
5641994 | Bollinger et al. | Jun 1997 | A |
5670823 | Kruger et al. | Sep 1997 | A |
5675159 | Oku et al. | Oct 1997 | A |
5802091 | Chakrabarti et al. | Sep 1998 | A |
5882532 | Field et al. | Mar 1999 | A |
5882738 | Blish, II et al. | Mar 1999 | A |
5935430 | Craig | Aug 1999 | A |
5955771 | Kurtz et al. | Sep 1999 | A |
6027957 | Merritt et al. | Feb 2000 | A |
6050145 | Olson et al. | Apr 2000 | A |
6058782 | Kurtz et al. | May 2000 | A |
6122974 | Sato et al. | Sep 2000 | A |
6191007 | Matsui et al. | Feb 2001 | B1 |
6234378 | Ford et al. | May 2001 | B1 |
6272928 | Kurtz | Aug 2001 | B1 |
6320265 | Chakrabarti et al. | Nov 2001 | B1 |
6363792 | Kurtz et al. | Apr 2002 | B1 |
6447923 | Yamakawa | Sep 2002 | B1 |
6452427 | Ko et al. | Sep 2002 | B1 |
6465271 | Ko et al. | Oct 2002 | B1 |
6530282 | Kurtz et al. | Mar 2003 | B1 |
6564644 | Kurtz | May 2003 | B1 |
6566158 | Eriksen et al. | May 2003 | B2 |
6586330 | Ludviksson et al. | Jul 2003 | B1 |
6595066 | Kurtz et al. | Jul 2003 | B1 |
6612178 | Kurtz et al. | Sep 2003 | B1 |
6706549 | Okojie | Mar 2004 | B1 |
6773951 | Eriksen et al. | Aug 2004 | B2 |
6845664 | Okojie | Jan 2005 | B1 |
6928878 | Eriksen et al. | Aug 2005 | B1 |
6932951 | Losey et al. | Aug 2005 | B1 |
6956268 | Faris | Oct 2005 | B2 |
20030108674 | Chung et al. | Jun 2003 | A1 |
20030201530 | Kurihara et al. | Oct 2003 | A1 |
20050042865 | Cabral et al. | Feb 2005 | A1 |
20060032582 | Chen et al. | Feb 2006 | A1 |
Number | Date | Country |
---|---|---|
10060439 | Jun 2002 | DE |
0119691 | Sep 1984 | EP |
0552466 | Jul 1993 | EP |
0585084 | Mar 1994 | EP |
2221570 | Feb 1990 | GB |
Number | Date | Country | |
---|---|---|---|
20060249847 A1 | Nov 2006 | US |