Source: https://patents.google.com/patent/US7078733B2/en
Timestamp: 2018-04-26 11:51:09
Document Index: 571515933

Matched Legal Cases: ['Application No. 02159777', 'Application No. 2002', 'Application No. 2002', 'Application No. 2002', 'Application No. 2002', 'Application No. 10']

US7078733B2 - Aluminum alloyed layered structure for an optical device - Google Patents
Aluminum alloyed layered structure for an optical device Download PDF
US7078733B2
US7078733B2 US10383058 US38305803A US7078733B2 US 7078733 B2 US7078733 B2 US 7078733B2 US 10383058 US10383058 US 10383058 US 38305803 A US38305803 A US 38305803A US 7078733 B2 US7078733 B2 US 7078733B2
US10383058
US20030168968A1 (en )
Yoshio Miyai
A layered structure of wire(s) comprising a wiring layer made of a low resistance metal containing aluminum, copper or silver; and an alloy layer made of an intermediate phase containing the low resistance metal and a refractory metal. The refractory metal is molybdenum. There is also formed a layered structure of wire(s) made of an aluminum alloy containing a lanthanoid, wherein a number average crystal grain size is 16.9 nm or more. Crystal grain size may be larger than a mean free path of electrons to provide a layered structure of wire(s) with a reduced resistance.
The present invention has been made in view of the foregoing circumstances and an objective therefor is to provide a highly reliable layered structure of wire(s) with a reduced resistance. Another object of the present invention is to provide a layered structure of wire(s) with improved electromigration resistance. Another objective of the present invention is to provide a layered structure of wire(s) with improved stress migration resistance. Further objective of the present invention is to provide a layered structure of wire(s) with improved durability. Further objective of the present invention is to improve an yield in a method of manufacturing a layered structure of wire(s).
According to the present invention, there is provided a method of manufacturing a layered structure of wire(s). The method comprises depositing an aluminum alloy containing a lanthanoid on the top surface of a substrate heated to 50° C. to 150° C. both inclusive by sputtering using the alloy as a target wherein the sputtering process is conducted maintaining the substrate and the target under a reduced pressure of 0.18/(M1/2×d) Pa or less in which M is the atomic weight of the target metal and d is a distance between the substrate and the target. The term “atomic weight” as used herein refers to an average atomic weight or the smallest atomic weight in main component metals when a target metal is an alloy. This method allows a number average crystal grain size to be larger than the mean free path of electrons, resulting in providing a layered structure of wire(s) with a reduced resistance. An intervening layer may be present between the substrate and the layered structure of wire(s).
After depositing the wiring layer, the layered structure of wire(s) may be heated to a temperature from the heating temperature of the substrate during the sputtering process to 450° C. both inclusive. Such heating may further reduce a resistance of the layered structure of wire(s).
According to the present invention, there is provided a layered structure of wire(s) comprising a wiring layer made of a metal containing aluminum, copper or silver; and an alloy layer made of an intermediate phase containing the metal constituting the wiring layer and a refractory metal which is adjacent to the wiring layer. The metal constituting the wiring layer may be an elemental metal such as aluminum, copper or silver, or an alloy containing 1 to 99% of aluminum, copper or silver. The metal constituting the wiring layer may have a lower specific resistance than the refractory metal. Hereinafter, a metal constituting the wiring layer is referred to as a “low resistance metal”.
According to the present invention, there is provided a method of manufacturing a layered structure of wire(s) comprising forming a protective layer on the top surface of a substrate heated to 50° C. to 150° C. both inclusive by sputtering using a refractory metal containing molybdenum as a target and forming a wiring layer on the protective layer while heating the substrate to 50° C. to 150° C. both inclusive by sputtering using a low resistance metal containing aluminum, copper or silver as a target, wherein the forming the protective layer and forming the wiring layer are conducted under a reduced pressure of 0.18/(M1/2×d) Pa or less in which M is the atomic weight of the target metal or, when the target metal is an alloy, an average in atomic % of the atomic weights of component metals or the smallest atomic weight in main component metals and d is a distance between the substrate and the target; and the forming the wiring layer is conducted without exposing the substrate to the air. According to this method, an intermediate phase can be formed between the protective layer and the wiring layer to consistently produce the layered structure of wire(s). Furthermore, adherence between the protective layer and the wiring layer may be improved and an yield in a method of manufacturing the layered structure of wire(s) may be improved. Herein, an intervening layer may be disposed between the substrate and the protective layer.
This method may further comprise heating the layered structure of wire(s) to a temperature from the heating temperature of the substrate during the sputtering process to 450° C. both inclusive after forming the wiring layer. Such heating may reduce a resistance of the layered structure of wire(s).
According to the present invention, there is also provided a method of manufacturing a layered structure of wire(s) comprising forming a wiring layer on the top surface of a substrate heated to 50° C. to 150° C. both inclusive by sputtering using a low resistance metal containing aluminum, copper or silver as a target and forming a protective layer on the wiring layer while heating the substrate to 50° C. to 150° C. both inclusive by sputtering using a refractory metal containing molybdenum as a target, wherein the forming the protective layer and forming the wiring layer are conducted under a reduced pressure of 0.18/(M1/2×d) Pa or less in which M is the atomic weight of the target metal or, when the target metal is an alloy, an average in atomic % of the atomic weights of component metals or the smallest atomic weight in main component metals and d is a distance between the substrate and the target; and the forming the protective layer is conducted without exposing the substrate to the air. According to this method, an intermediate phase can be formed between a wiring and a protective layers to consistently produce a layered structure of wire(s). Furthermore, adherence between the wiring layer and the protective layer may be improved and an yield in a method of manufacturing the layered structure of wire(s) may be improved. Herein, an intervening layer may be disposed between the substrate layer and the wiring layer.
This method may further comprise heating the layered structure of wire(s) to a temperature from the heating temperature of the substrate during the sputtering process to 450° C. both inclusive after forming the protective layer. Such heating may reduce a resistance of the layered structure of wire(s).
According to the present invention, there is also provided a method of manufacturing a layered structure of wire(s) comprising forming a wiring layer on the top surface of a substrate by sputtering using a low resistance metal containing aluminum, copper or silver as a target and forming a protective layer by sputtering using a refractory metal containing molybdenum as a target such that the protective layer is formed in contact with the wiring layer, wherein the forming the wiring layer and forming the protective layer are conducted under the conditions with a substantially equivalent particle collision parameter represented by P×M1/2×d where P is a sputtering pressure, M is the atomic weight of the target metal or, when the target metal is an alloy, an average in atomic % of the atomic weights of component metals or the smallest atomic weight in main component metals and d is a distance between the substrate and the target. The term “atomic weight” as used herein refers to an average atomic weight or the smallest atomic weight in main component metals when a target metal is an alloy. Substantially equivalent conditions are, for example, those where a particle collision parameter ratio is 0.9 to 1.1 both inclusive.
FIG. 1 is a plan view illustrating one pixel in an organic EL display.
FIG. 2A shows a cross section on line A—A in the pixel illustrated in FIG. 1.
FIG. 2B shows a cross section on line B—B in the pixel illustrated in FIG. 1.
FIG. 2A shows a cross section on line A—A in FIG. 1 while FIG. 2B shows a cross-section on line B—B in FIG. 1. As illustrated in FIG. 2A, an active layer 13 is formed on an insulating substrate 10. The insulating substrate 10 may be made of, for example, quartz glass or non-alkali glass. The active layer 13 may be made of a polycrystalline silicon (p-Si) film formed by polycrystallizing by irradiation of amorphous silicon (a-Si) film with laser beam. In this figure, a top gate structure is illustrated, but the present invention is not limited to the specific structure. The active layer 13 comprises a source electrode 13 s and a drain electrode 13 d on both sides of two channels 13 c. In this embodiment, the source electrode 13 s and the drain electrode 13 d are ion-doped with an n-type dopant, and the first TFT 30 is of an n-channel type.
Alternatively, the wiring layer 112 may contain a lanthanoid such as neodymium. A lanthanoid may be added to a low resistance metal such as aluminum to improve electromigration resistance of a layered structure of wire(s). In this embodiment, the wiring layer 112 is made of an aluminum-neodymium alloy (Nd—Al). In this embodiment, a neodymium content in the aluminum-neodymium alloy is 2 atomic %.
First, the LL chamber, the handling chamber, the first sputtering chamber and the second sputtering chamber were pre-vacuumed to 10−3 Pa and a substrate was then carried from the LL chamber to the handling chamber. Opening a gate valve between the handling chamber and the first sputtering chamber, the substrate was carried into the first sputtering chamber and then heated to 100° C. Then, Ar gas was introduced into the first sputtering chamber to 0.23 Pa. Sputtering was conducted under the conditions of a power: 6.2 kW and a flow rate of Ar gas: 100 sccm to deposit the first protective layer made of molybdenum to 50 nm. Observation of a TEM (transmission electron microscopy photograph), which will be explained in the following, indicated that the first protective layer thus deposited adhered to the base interlayer insulating film with good adherence.
In the second sputtering chamber, the substrate was heated to 100° C. Then, Ar gas was introduced into the second sputtering chamber to 0.41 Pa. Sputtering was conducted under the conditions of a power: 6.5 kW and a flow rate of Ar gas: 100 sccm to deposit a wiring layer made of an aluminum-neodymium alloy to 400 nm.
Again, the second sputtering chamber was vacuumed to 10−3 Pa, and the substrate was then carried to the first sputtering chamber via the handling chamber. In the first sputtering chamber, the substrate was heated to 100° C. Then, Ar gas was introduced into the first sputtering chamber to 0.23 Pa. Sputtering was conducted under the conditions of a power: 6.2 kW and a flow rate of Ar gas: 100 sccm to deposit the second protective layer made of molybdenum to 100 nm. In this example, a distance between the substrate and the target was 0.05 m in the first and the second sputtering chambers.
After pattering the multilayer structure thus formed, the substrate was heated at 350° C. for 30 min.
A probability of collision is proportional to a cross-sectional area of a particle and a pressure P in a sputtering chamber. A mean free path is proportional to a particle velocity v and inversely proportional to a collision probability. Thus, the relationship can be represented by λ∝v/(P×S). A velocity of each particle v is represented by E=1/2×mv2, where m is a particle weight. Here, m may be expressed as m∝m, where M is an atomic weight of a target metal although it is an average atomic weight or the smallest atomic weight in main metals when the target metal is an alloy, and an average energy of particles released from the target is constant at 5 to 10 eV independently of the type of the atom or the target. There is, therefore, a relationship, v∝(1/M)1/2. Thus, a mean free path λ can be represented by λ∝1/(M1/2×P×S). In other words, when the distance d between the substrate and the target is constant, it is preferable to reduce a pressure in the sputtering chamber as much as possible. A cross-sectional area of a particle can be approximate to πr2 where r is an atomic radius. Since an atomic radius r of a metal preferably used in this embodiment is constant at about 1.25 to 1.45 Å, S can be expressed as a constant.
As described above, a mean free path λ can be represented by λ∝1/(M1/2×P×S) and can be controlled by varying a molecular weight M of each particle and a pressure P in a sputtering chamber. In other words, it is preferable that a pressure in a sputtering chamber is low and a pressure in the sputtering chamber should be lower for particles having a larger molecular weight M.
Since the particle collision parameter described above can be represented by P×M1/2×d, reduction in a distance d between the substrate and the target can be similarly effective. In this embodiment, a distanced between the substrate and the target may be 0.1 m or less.
In this embodiment, a pressure P in the sputtering chamber may be selected such that a particle collision parameter P×M1/2×d is 0.18 or less. A pressure P in the sputtering chamber may be, therefore, 0.18/(M1/2×d) or less. Thus, a layered structure of wire(s) with a large crystal size can be consistently formed, and furthermore, an intermediate phase can be consistently formed. The lower limit for a pressure P in the sputtering chamber is preferably 0.1 Pa, whereby each layer can be consistently deposited.
A substrate temperature during sputtering may be 50° C. to 150° C. both inclusive. In addition, heating may be conducted at a temperature from the substrate temperature during sputtering to 450° C. both inclusive.
As seen in FIGS. 7A and 7B, major particles are those with a size of 60 nm to 70 nm. In these figures, 112 of the total 118 extracted ellipses have a crystal grain size of more than 30 nm and account for about 95% (112/118×100). Similarly, 74 ellipses have a crystal grain size of more than 60 nm and account for about 62% (74/118×100). A number average crystal grain size of the crystals is 69.55 nm, which is calculated by dividing the total of the sizes of the particles from the ellipses illustrated in FIG. 6B (8207.9 nm) by the total particle number (118) as described above. Furthermore, few particles with a size of less than 25 nm were formed. In other words, the method of manufacturing the layered structure of wire(s) according to the present invention provided a layered structure of wire(s) comprised of crystal particles of an aluminum-neodymium alloy having a size of more than 16.9 nm which is a mean free path of electrons in aluminum.
The layered structure of wire(s) thus formed had a specific resistance of 15 μΩcm immediately after deposition, and 4.8 μΩcm after heating at 350° C. for 30 minutes.
As a reference example, a layered structure of wire(s) was formed using an aluminum-neodymium alloy with a neodymium content of 2 atomic % as a target under the conditions of a substrate temperature: 100° C., a pressure in the second sputtering chamber: 0.70 Pa and an argon flow rate: 200 sccm. In this case, the layered structure of wire(s) had a specific resistance of 21.5 μΩcm immediately after deposition. This reference example also indicates that a resistance was reduced in the layered structure of wire(s) formed according to the process in the above example. Furthermore, the above results also indicate that a resistance in a layered structure of wire(s) can be sufficiently reduced at a sputtering chamber pressure P of less than 0.18/(M1/2×d), and thus imply that the crystals could have a large crystal grain size under such conditions.
FIGS. 9A and 9B show the results of measuring a metal composition in the second alloy layer by energy dispersive X-ray spectroscopy (EDS). FIG. 9A shows a cross section near the second alloy layer while FIG. 9B shows a metal composition at each position indicated in FIG. 9A. As seen in FIG. 9B, the second alloy layer region has an aluminum content of about 80 to 90 atomic %, a molybdenum content of about 7 to 15 atomic % and a neodymium content of about 1˜4 atomic %.
FIG. 10 shows a binary phase diagram for aluminum and molybdenum (“Binary Alloy Phase Diagrams Volume 1”, Thaddeus B. Massalski, American Society for Metals). As shown in this figure, an intermetallic compound of aluminum and molybdenum may be, for example, Mo3Al, MoAl, Mo37Al63, Mo3Al8, MoAl4, Mo4Al17, Mo5Al22, MoAl5, MoAl6 or MoAl12, and so on. These results imply that one of these intermetallic compounds are formed in the first alloy layer 116 and the second alloy layer 118. Furthermore, since the wiring layer 112 is made of an aluminum-neodymium alloy in this embodiment, an intermetallic compound containing neodymium could be formed.
As a reference example, a layered structure of wire(s) was formed as described above, except that deposition was conducted at room temperature (about 23° C.) without heating a substrate. Observation of a cross section by TEM indicated that the layered structure of wire(s) was lifted during the subsequent processing.
As another reference example, deposition was conducted under the conditions of a pressure in the first sputtering chamber: about 0.40 Pa and a pressure in the second sputtering chamber: about 0.70 Pa. Again, observation of a cross section by TEM indicated that the layered structure of wire(s) was lifted during the subsequent processing. The results in these reference examples also confirm that in the layered structure of wire(s) formed according to this embodiment, adherence between the wiring layer and the protective layer was improved. These results also imply that an intermediate phase could be consistently formed when a pressure P in the sputtering chamber is 0.18/(M1/2×d) or less.
US10383058 2002-03-07 2003-03-07 Aluminum alloyed layered structure for an optical device Active 2023-07-24 US7078733B2 (en)
JP2002062670A JP2003264192A (en) 2002-03-07 2002-03-07 Wiring structure, manufacturing method, and optical device
JPJP2002-062670 2002-03-07
JPJP2002-066143 2002-03-11
JP2002066143A JP2003264193A (en) 2002-03-11 2002-03-11 Wiring structure, manufacturing method, and optical device
US20030168968A1 true US20030168968A1 (en) 2003-09-11
US7078733B2 true US7078733B2 (en) 2006-07-18
ID=27791005
US10383058 Active 2023-07-24 US7078733B2 (en) 2002-03-07 2003-03-07 Aluminum alloyed layered structure for an optical device
US (1) US7078733B2 (en)
KR (1) KR100582130B1 (en)
CN (1) CN100517422C (en)
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US20030168968A1 (en) 2003-09-11 application
JP2005038842A (en) 2005-02-10 Display device and manufacturing method thereof
JP2003114626A (en) 2003-04-18 Light emitting device and method for manufacturing the same
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