# Patent

## Title
Infrared control coating of thin film devices

## Abstract

Systems and methods for creating an infrared-control coated thin film device with certain visible light transmittance and infrared reflectance properties are disclosed. The device may be made using various techniques including physical vapor deposition, chemical vapor deposition, thermal evaporation, pulsed laser deposition, sputter deposition, and sol-gel processes. In particular, a pulsed energy microwave plasma enhanced chemical vapor deposition process may be used. Production of the device may occur at speeds greater than 50 Angstroms/second and temperatures lower than 200° C.

## Background
RELATED APPLICATION
This application claims priority to, and the benefit of, U.S. Provisional Patent Application No. 61/829,807 filed May 31, 2013, the disclosure of which is hereby incorporated by reference herein in its entirety.


GOVERNMENT LICENSE RIGHTS
This invention was made with government support under grant # DE-EE0006348 awarded by the Department of Energy.


INTRODUCTION
Thin films are used in a variety of applications. For example, thins films are used in window assemblies. The window assembly has a window pane, and thin films can be deposited onto the window pane. Additionally, a thin film may be deposited on a thin substrate that can then be adhered to the window surface or applied to an insert that is then inserted into a window assembly.
Depending on the type of film used and the material of the window pane, depositing or inserting thin films on window panes can alter certain properties of the window pane. For example, thin films alter the transmittance of light through the window pane. A thin film may reduce the amount of visible light that passes through the window pane. Additionally, certain thin films reduce the amount of infrared light that passes through the window pane.
For certain applications, it is desirous to control the transmittance of specific wavelengths of electromagnetic radiation through a window pane. For example, a window assembly may be used as part of a structure that forms an internal space. As such, it may be desirous to control the temperature of the internal space. Additionally, it may also be desirous to allow people to see through the window. Using a thin film that reduces the amount of infrared light that passes through the window would reduce the total energy entering or exiting the internal space. Consequently, less energy would be required to keep the space at the desired temperature than if all infrared light were allowed to pass through the window. Furthermore, it may also be desirous to allow more transmittance of visible light through the window pane because doing so would allow people to see through the window easier than if the transmittance was low.
Thus, a thin film that could decrease the amount of infrared light that passed through the window pane while still allowing a significant amount of visible light is useful for certain applications.
It is with respect to these and other considerations that embodiments have been disclosed. Also, although relatively specific problems have been discussed, it should be understood that the embodiments should not be limited to solving the specific problems identified in the introduction.
Various embodiments are described more fully below with reference to the accompanying drawings, which form a part hereof, and which show specific exemplary embodiments. However, embodiments may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the embodiments to those skilled in the art. Embodiments may be practiced as methods, systems or devices. The following detailed description is, therefore, not to be taken in a limiting sense.
Infrared Control Coating of Thin Film Devices
Systems and methods for creating an infrared-control coated thin film device with certain visible light transmittance and infrared reflectance properties are disclosed. The device may be made using various techniques including physical vapor deposition, chemical vapor deposition, thermal evaporation, pulsed laser deposition, sputter deposition, and sol-gel processes. In particular, a pulsed energy microwave plasma enhanced chemical vapor deposition process may be used. Production of the device may occur at static deposition rates greater than 50 Angstroms/second and substrate temperatures lower than 200° C.
{Claim Summary Section. Completed after Approval of Final Version Claims}
These and various other features as well as advantages which characterize the systems and methods described herein will be apparent from a reading of the following detailed description and a review of the associated drawings. Additional features are set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the technology. The benefits and features of the technology will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.



BRIEF DESCRIPTION OF THE DRAWINGS
Non-limiting and non-exhaustive embodiments are described with reference to the following figures:
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.
FIG. 1 illustrates an example of a multilayered infrared-control coated thin film device.
FIG. 2 is a graphical representation of modeled transmittance and reflectance properties of a 4-layer thin film device.
FIG. 3 is a graphical representation of modeled transmittance and reflectance properties of a 6 layer thin film device.
FIG. 4 is a graphical representation of modeled transmittance and reflectance properties of a three layer thin film device.
FIG. 5 is a graphical representation of modeled transmittance and reflectance properties of an eight layer thin film device.
FIG. 6 illustrates a roll-to-roll system for depositing one or more layers on a substrate.
FIG. 7 illustrates an example waveform of a pulsed microwave that may be used in conjunction systems and methods described herein.
FIG. 8 is an embodiment of a method for manufacturing a multilayered infrared-control coated device.
FIG. 9 illustrates the prior art of a planar sputtering cathode system.
FIG. 10 illustrates a thin film with interstitial voids.
FIG. 11 illustrates the prior art of an RF waveform super positioned on a pulsed DC waveform.
FIG. 12 illustrates a waveform that combines an RF waveform super positioned on pulsed-DC with a reverse voltage limiting threshold.
FIG. 13 illustrates the expected resistivity properties of thin films when a waveform 300 is applied to a cathode.
FIG. 14 illustrates the expected resistivity properties of thin films when a composite waveform 400 is applied to a cathode.
FIG. 15 illustrates a method of applying an RF waveform super positioned on a pulsed DC waveform combined with reverse voltage threshold to a cathode of a sputtering deposition process.
FIG. 16 illustrates a system to apply an RF and pulsed DC waveform combined with reverse voltage threshold to a cathode of a sputtering deposition process.
FIG. 15A illustrates the apply a pulsed DC waveform to a cathode operation.
FIG. 15B illustrates an apply an RF waveform operation.



DETAILED DESCRIPTION
Various embodiments are described more fully below with reference to the accompanying drawings, which form a part hereof, and which show specific exemplary embodiments. However, embodiments may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the embodiments to those skilled in the art. Embodiments may be practiced as methods, systems or devices. The following detailed description is, therefore, not to be taken in a limiting sense.
Systems and method for producing infrared control coating on thin film devices are disclosed herein. Production of such devices may occur at a relatively low temperature and a relatively high speed. Though the materials are discussed with specificity, it will be appreciated that that various materials may be used in conjunction with the technology disclosed herein is not so limited. The systems and methods described herein may be used to create thin films that are amorphous, polycrystalline, nanocrystalline, nanocrystalline in an amorphous matrix, or ultra-nanocrystalline in an amorphous matrix. Such a matrix may provide a balance between infrared modulation and high visible transmission that may complement the response of the infrared reflection.
The technology described herein may be used in a variety of applications. For example, the technology may be deposited directly onto a window glass pane before integration into a window, deposited onto a stand-alone film that can be adhered directly to a window surface, or deposited onto a stand alone film that can be adhered to a thin plastic or glass substrate and later inserted into a window. The infrared control film may also be used in conjunction with an electrochromic device or other dynamic window system to provide a combination of active and passive control of heat flow through the window system.
Any actively controlled dynamic window glazing, such as an electrochromic device or motorized shading system, may be used in conjunction with a multilayered infrared-control coated thin film device, such as a dielectric stack, that is designed to control the infrared transmittance and reflectance. Further, the infrared-control coatings may be deposited on the same substrate as an electrochromic device, a window pane, an insert, or another substrate. Both the infrared control coating and the electrochromic device may adhere to an insert that fits between two panes of a window assembly or fits into the window well of an existing window. Alternatively, one or both panes may be coated with the thin film. The use of such coating may reduce infrared transmission while still maintaining high transparency with respect to the visible range of light. For example, the average transmittance of the visible light range (i.e., 400-730 nm) may be greater than 90% transparency while maintaining an average reflectance of solar infrared spectrum (i.e., 750-2500 nm) of greater than 70%. It should be noted that achieving other average transmittance and reflectance percentage rates at particular range of wavelengths may be desirous, e.g., any percentage between 0 and 100%.
Unless otherwise specified, the term visible light spectrum refers to the spectrum of light that is detectable by the human eye. For the purposes of this document, the visible spectrum is from about 400 to 730 nanometers (nm) in wavelength. Additionally, unless otherwise specified, the term infrared spectrum refers to the spectrum of light that is longer than those of visible light. Unless otherwise stated, the infrared region will refer to two discrete regions. First, the solar infrared from  ̃750-2500 nm and the thermal infrared at wavelengths 2500-50,000 nm. The infrared control coating described herein may control one or both of these regions by varying the materials choices, thickness, and deposition technique.
FIG. 1 illustrates an example of an infrared-control coated thin film device 100. As illustrated, the infrared-control coated thin film device 100 includes a substrate 102, a first layer 104, a second layer 106, and a third layer 108, and a fourth layer 110. In other embodiments, more or less layers may be present.
The substrate 102 is a transparent thin foil upon which other layers are deposited. In an embodiment, these layers are inorganic dielectric layers. The substrate 102 may be flexible or rigid. For example, the substrate 102 may be a material with a relatively low melting point compared to glass. In an embodiment, the substrate 102 is one of polyethylene terephthalate (“PET”), polyethylene napthalate (PEN), polycarbonate, transparent polymides, etc. In other embodiments, the substrate 102 may be a transparent organic polymer or a transparent inorganic polymer. Still in other embodiments, the substrate 102 is a ceramic or glass.
One or more layers of materials may be deposited onto the substrate 102. Deposition of infrared-control layers will alter the transmittance and reflectance properties of the resulting infrared-control coated thin film device. Transmittance and reflectance properties are controlled through controlling layer material type, layer thickness, and layer quality.
Materials that may be deposited on a substrate include any transparent conductive oxide. Example transparent conductive oxides include gallium doped zinc oxide (“GZO”), indium tin oxide (“ITO”), Other materials include dielectric layers. Example dielectric materials are silicon dioxide (“SiO2”), titanium dioxide (“TiO2”), Alumina (“Al2O3”), and zinc oxide (“ZnO”). Other materials such as metals, may be used including silver (Ag) and gold (Au).
Each layer may be of a different material. Additionally, the same material may be used for multiple layers. For example, in one embodiment, the first layer 104 is GZO, the second layer 106 is SiO2, the third layer 108 is TiO2, and the fourth layer 110 is SiO2. In another embodiment, there are more than four layers deposited onto a substrate 102. For example, a device may include layers of material in the following order: GZO, SiO2, TiO2, SiO2, TiO2, and SiO2. Layers may also include alloys of materials. Mixing materials together may help achieve a refractive index that is not easily achieved with a pure material.
Layer thickness may vary. Additionally, each layer may be of varying thickness relative to other layers. As illustrated, first layer 104 is thinner than third layer 108, which is thinner than second layer 106, which is thinner than forth layer 110. It will be appreciated that the FIG. 1 is not intended to be a to-scale illustration. In other embodiments, each layer is roughly the same size. In an embodiment, the first layer 104, the second layer 106, the third layer 108, and the fourth layer 110 may have a thickness that ranges from 40 nm to 400 nano-meters.
Layer quality may be controlled by controlling process parameters during deposition of the material. Process parameters include temperature and pressure of a process chamber, and ion energy of plasma. For example, ion energy may be controlled during deposition processes such as sputtering deposition or microwave-enhanced chemical vapor deposition. Controlling the energy of the ions allows a layer, such as first layer 104, to be deposited without or with very few interstitial voids while allowing proper film growth. This occurs because the energy of the ions affects the energy of deposition material as it strikes the substrate 102. Material striking a substrate 102 with too high energy may disrupt the structure of material previously deposited onto the substrate 102, thereby creating void spaces in the layer. Material having too low of energy may fail to form proper lattice structures. This will affect the properties of the deposited layer and ultimately the transmittance and reflectance properties of the device itself. One way to control ion material is through pulsed-chemical vapor deposition, which is discussed in more detail with reference to FIG. 7, below.
The device 100 will have certain reflectance and transmittance properties that are affected by the quality and materials of layers, such as first layer 104, second layer 106, third layer 108, and fourth layer 110. Using the technology described herein, embodiments of infrared-control coated thin film devices have been created having particularly advantageous transmittance and reflectance properties.
For the purpose of this discussion, and particularly with reference to FIGS. 2 through 5, the percent reflectance is defined as the percentage of light at a particular wavelength that is reflected from the thin film device.
Certain layers in the infrared control coating may be deposited using pulsed-energy controlled microwave plasma enhanced chemical vapor deposition. In an embodiment, the film is grown from liquid precursors with substantial vapor pressure such as hexamethyldisiloxane (HMDSO), diethyl zinc (DEZ), trimethyl aluminum (TMA), etc. and gases such as argon or oxygen. The liquid precursors and oxygen are fed into a deposition zone to achieve a total pressure from 10-400 mTorr. A plasma is generated with a linear microwave source which can partially dissociate the precursors enhancing their chemical reactivity and facilitating film growth on the substrate. The film growth may be further aided by increasing the temperature of the substrate.
Average transmittance and reflectance are described with reference to particular ranges of the electromagnetic spectrum.
In an embodiment of the infrared-control coated thin film device, the average transmittance of light in the range of about 400 to 730 nm is greater than 90% while maintaining an average reflectance of light from 700 nm to 2500 nm of greater than 48%. In another embodiment, the average transmittance is greater 90% while the reflectance is greater than 50%. In another embodiment, the average transmittance is greater than 95% while the reflectance is greater than 55%.
FIGS. 2 through 5 are graphical representations of the modeled reflectance and transmittance properties of dielectric thin film devices that may be created using the methods described herein. FIG. 2 is a graph 200 of the modeled reflectance and transmittance for a dielectric thin film device with PET as the substrate, GZO as a first layer, SiO2 as a second layer, TiO2 as a third layer, and SiO2 as a fourth layer. The graph 200 includes a reflectance line 202 and a transmittance line 204. The visible spectrum 206 is from about 400 nm to about 730 nm. The infrared spectrum 208 illustrated on graph 200 is from about 750 to about 2500 nm. As illustrated, the average transmittance in the visible light range is about 92.12%. Further, the average reflectance in the infrared spectrum is about 50.52%.
Table 1 is a table of the reflectance and transmittance used to generate graph 200.









TABLE 1





Wavelength




(nm)
Reflectance
Transmittance

















250
2.13
74.85


260
3.50
73.67


270
10.61
69.82


280
13.84
68.12


290
23.74
59.95


300
30.80
54.16


310
28.93
56.11


320
21.51
63.10


330
15.53
69.00


340
14.96
69.89


350
17.15
68.22


360
17.68
68.17


370
14.38
76.36


380
8.19
85.00


390
3.13
91.20


400
1.79
93.37


410
3.19
92.73


420
4.78
91.83


430
4.98
92.19


440
3.75
93.90


450
2.06
95.85


460
1.07
97.05


470
1.25
97.10


480
2.23
96.34


490
3.27
95.54


500
3.75
95.18


510
3.49
95.41


520
2.64
96.21


530
1.58
97.21


540
0.73
98.02


550
0.37
98.34


560
0.57
98.09


570
1.25
97.37


580
2.19
96.34


590
3.18
95.23


600
4.09
94.21


610
4.87
93.32


620
5.54
92.53


630
6.18
91.78


640
6.89
90.97


650
7.76
90.00


660
8.85
88.83


670
10.17
87.45


680
11.69
85.87


690
13.35
84.17


700
15.07
82.42


710
16.78
80.68


720
18.42
79.02


730
19.95
77.47


740
21.32
76.08


750
22.52
74.86


760
23.54
73.82


770
24.39
72.94


780
25.08
72.22


790
25.64
71.64


800
26.08
71.16


810
26.45
70.75


820
25.56
71.31


830
25.91
70.67


840
26.26
70.03


850
26.63
69.37


860
27.02
68.69


870
27.43
67.99


880
27.84
67.28


890
28.27
66.57


900
28.68
65.85


910
29.08
65.16


920
29.45
64.48


930
29.77
63.85


940
30.04
63.26


950
30.24
62.73


960
30.36
62.25


970
30.40
61.85


980
30.34
61.52


990
30.20
61.26


1000
29.95
61.08


1010
29.61
60.97


1020
29.17
60.93


1030
28.64
60.95


1040
28.03
61.03


1050
27.33
61.15


1060
26.58
61.31


1070
25.77
61.48


1080
24.92
61.67


1090
24.06
61.85


1100
23.21
62.00


1110
22.38
62.10


1120
21.61
62.14


1130
20.92
62.09


1140
20.34
61.94


1150
19.89
61.67


1160
19.59
61.26


1170
19.47
60.70


1180
19.54
60.00


1190
19.82
59.13


1200
20.31
58.11


1210
21.01
56.94


1220
21.91
55.63


1230
23.00
54.19


1240
24.27
52.65


1250
25.69
51.02


1260
27.25
49.32


1270
28.91
47.57


1280
30.66
45.79


1290
32.47
44.00


1300
34.32
42.22


1310
36.18
40.46


1320
38.04
38.74


1330
39.89
37.06


1340
41.70
35.43


1350
43.46
33.86


1360
45.18
32.35


1370
46.83
30.91


1380
48.43
29.53


1390
49.95
28.22


1400
51.40
26.98


1410
52.79
25.81


1420
54.10
24.70


1430
55.34
23.65


1440
56.51
22.66


1450
57.62
21.72


1460
58.66
20.84


1470
59.64
20.01


1480
60.55
19.23


1490
61.41
18.50


1500
62.21
17.81


1510
62.95
17.16


1520
63.65
16.54


1530
64.29
15.97


1540
64.89
15.43


1550
65.45
14.92


1560
65.96
14.45


1570
66.43
14.00


1580
66.87
13.58


1590
67.28
13.18


1600
67.65
12.81


1610
67.99
12.46


1620
68.31
12.14


1630
68.60
11.83


1640
68.86
11.53


1650
69.10
11.26


1660
69.33
11.00


1670
69.53
10.75


1680
69.71
10.52


1690
69.87
10.30


1700
70.02
10.09


1710
70.15
9.89


1720
70.27
9.70


1730
70.37
9.53


1740
70.46
9.36


1750
70.53
9.20


1760
70.59
9.05


1770
70.64
8.90


1780
70.67
8.76


1790
70.69
8.63


1800
70.70
8.51


1810
70.70
8.39


1820
70.69
8.28


1830
70.66
8.17


1840
70.63
8.07


1850
70.58
7.98


1860
70.52
7.89


1870
70.46
7.80


1880
70.38
7.72


1890
70.29
7.65


1900
70.19
7.58


1910
70.08
7.51


1920
69.96
7.45


1930
69.83
7.39


1940
69.69
7.34


1950
69.53
7.29


1960
69.37
7.24


1970
69.20
7.20


1980
69.01
7.16


1990
68.82
7.13


2000
68.49
7.30


2010
68.16
7.47


2020
67.83
7.64


2030
67.50
7.81


2040
67.16
7.99


2050
66.83
8.17


2060
66.49
8.35


2070
66.14
8.53


2080
65.80
8.72


2090
65.45
8.91


2100
65.10
9.10


2110
64.74
9.29


2120
64.39
9.49


2130
64.03
9.69


2140
63.67
9.89


2150
63.31
10.09


2160
62.95
10.30


2170
62.58
10.50


2180
62.21
10.72


2190
61.84
10.93


2200
61.47
11.14


2210
61.10
11.36


2220
60.72
11.58


2230
60.34
11.80


2240
59.97
12.03


2250
59.59
12.25


2260
59.20
12.48


2270
58.82
12.71


2280
58.44
12.95


2290
58.05
13.18


2300
57.67
13.42


2310
57.28
13.66


2320
56.89
13.90


2330
56.50
14.14


2340
56.11
14.39


2350
55.72
14.64


2360
55.32
14.88


2370
54.93
15.14


2380
54.54
15.39


2390
54.14
15.64


2400
53.75
15.90


2410
53.35
16.16


2420
52.95
16.42


2430
52.56
16.68


2440
52.16
16.94


2450
51.76
17.21


2460
51.37
17.47


2470
50.97
17.74


2480
50.57
18.01


2490
50.17
18.28


2500
49.77
18.55









FIG. 3 is a graph 300 of the reflectance and transmittance for a dielectric thin film device with PET as the substrate, SiO2 as a first layer at a thickness of 360.45 nm, TiO2 as a second layer at 106.14 nm, SiO2 as a third layer at a thickness of 168.89 nm, TiO2 as a fourth layer at a thickness of 91.85 nm, and SiO2 as a fifth layer at a thickness of 72.12 nm. The graph 300 includes a reflectance line 302 and a transmittance line 304. The visible spectrum 306 is from about 400 nm to about 730 nm. The infrared spectrum 308 is illustrated on graph 300 from about 750 to about 2500 nm. As illustrated, the average transmittance in the visible light range is about 95.46%. Further, the average reflectance in the infrared spectrum is about 52.31%.
Table 2 is a table of the reflectance and transmittance used to generate graph 300.









TABLE 2





Wavelength




(nm)
Reflectance
Transmittance

















250
23.07
52.08


260
11.82
59.68


270
7.04
59.48


280
33.19
43.62


290
30.25
48.11


300
24.02
53.53


310
17.51
58.21


320
43.93
37.90


330
58.88
26.06


340
58.24
25.94


350
50.91
31.30


360
44.56
35.88


370
40.14
47.24


380
30.26
61.32


390
16.67
76.60


400
5.00
89.04


410
0.55
94.31


420
1.00
94.77


430
1.19
95.29


440
0.45
96.70


450
0.28
97.24


460
0.73
97.04


470
0.85
97.16


480
0.43
97.81


490
0.04
98.49


500
0.09
98.63


510
0.40
98.32


520
0.57
98.13


530
0.52
98.14


540
0.58
98.04


550
1.12
97.48


560
2.20
96.39


570
3.50
95.05


580
4.57
93.89


590
5.06
93.28


600
4.85
93.34


610
4.06
93.98


620
2.95
94.92


630
1.81
95.88


640
0.87
96.65


650
0.26
97.12


660
0.01
97.23


670
0.11
97.02


680
0.55
96.48


690
1.40
95.55


700
2.75
94.15


710
4.71
92.16


720
7.33
89.54


730
10.59
86.32


740
14.38
82.59


750
18.53
78.53


760
22.81
74.35


770
27.03
70.22


780
31.04
66.32


790
34.73
62.73


800
38.04
59.50


810
40.99
56.63


820
42.65
54.78


830
44.76
52.53


840
46.64
50.50


850
48.32
48.68


860
49.84
47.02


870
51.23
45.49


880
52.51
44.08


890
53.70
42.76


900
54.80
41.52


910
55.82
40.37


920
56.75
39.30


930
57.59
38.33


940
58.33
37.44


950
58.96
36.66


960
59.47
35.98


970
59.86
35.42


980
60.11
34.97


990
60.23
34.64


1000
60.21
34.42


1010
60.03
34.33


1020
59.71
34.36


1030
59.24
34.50


1040
58.63
34.75


1050
57.87
35.11


1060
56.97
35.56


1070
55.94
36.10


1080
54.80
36.71


1090
53.57
37.37


1100
52.26
38.06


1110
50.91
38.76


1120
49.55
39.44


1130
48.22
40.06


1140
46.97
40.59


1150
45.84
41.01


1160
44.88
41.27


1170
44.11
41.37


1180
43.58
41.27


1190
43.29
40.98


1200
43.27
40.49


1210
43.49
39.82


1220
43.94
38.98


1230
44.60
38.02


1240
45.42
36.94


1250
46.38
35.79


1260
47.43
34.60


1270
48.53
33.38


1280
49.66
32.17


1290
50.78
30.99


1300
51.87
29.84


1310
52.90
28.75


1320
53.88
27.71


1330
54.78
26.74


1340
55.59
25.84


1350
56.32
25.00


1360
56.95
24.23


1370
57.49
23.52


1380
57.93
22.88


1390
58.27
22.30


1400
58.53
21.78


1410
58.69
21.31


1420
58.75
20.90


1430
58.73
20.53


1440
58.61
20.22


1450
58.41
19.94


1460
58.12
19.71


1470
57.74
19.51


1480
57.28
19.35


1490
56.73
19.22


1500
56.10
19.13


1510
55.38
19.06


1520
54.59
19.02


1530
53.72
19.00


1540
52.77
19.01


1550
51.75
19.04


1560
50.67
19.09


1570
49.53
19.15


1580
48.33
19.22


1590
47.09
19.30


1600
45.81
19.39


1610
44.51
19.48


1620
43.19
19.56


1630
41.87
19.64


1640
40.56
19.71


1650
39.27
19.77


1660
38.03
19.81


1670
36.85
19.82


1680
35.74
19.81


1690
34.73
19.77


1700
33.81
19.70


1710
33.02
19.59


1720
32.37
19.45


1730
31.86
19.26


1740
31.50
19.04


1750
31.30
18.78


1760
31.26
18.48


1770
31.38
18.15


1780
31.65
17.79


1790
32.08
17.39


1800
32.66
16.98


1810
33.36
16.54


1820
34.19
16.08


1830
35.12
15.61


1840
36.15
15.13


1850
37.25
14.65


1860
38.42
14.16


1870
39.64
13.68


1880
40.90
13.20


1890
42.18
12.73


1900
43.47
12.27


1910
44.76
11.83


1920
46.05
11.39


1930
47.33
10.98


1940
48.58
10.57


1950
49.81
10.19


1960
51.00
9.82


1970
52.16
9.47


1980
53.29
9.13


1990
54.37
8.81


2000
55.01
8.81


2010
55.63
8.81


2020
56.24
8.81


2030
56.83
8.81


2040
57.40
8.81


2050
57.95
8.81


2060
58.48
8.81


2070
59.00
8.82


2080
59.49
8.82


2090
59.97
8.83


2100
60.43
8.84


2110
60.87
8.85


2120
61.30
8.86


2130
61.70
8.87


2140
62.10
8.88


2150
62.47
8.90


2160
62.83
8.91


2170
63.18
8.93


2180
63.51
8.95


2190
63.83
8.97


2200
64.13
8.99


2210
64.42
9.02


2220
64.69
9.04


2230
64.96
9.07


2240
65.21
9.10


2250
65.45
9.13


2260
65.68
9.16


2270
65.89
9.20


2280
66.10
9.23


2290
66.30
9.27


2300
66.48
9.31


2310
66.66
9.35


2320
66.82
9.39


2330
66.98
9.43


2340
67.13
9.48


2350
67.27
9.53


2360
67.40
9.57


2370
67.52
9.62


2380
67.64
9.67


2390
67.74
9.73


2400
67.84
9.78


2410
67.94
9.84


2420
68.02
9.89


2430
68.10
9.95


2440
68.17
10.01


2450
68.24
10.07


2460
68.30
10.13


2470
68.35
10.20


2480
68.40
10.26


2490
68.44
10.33


2500
68.48
10.40









FIG. 4 is a graph 400 of the reflectance and transmittance for a dielectric thin film device with PET as the substrate, ZnO as a first layer at a thickness of 48.86 nm, Ag as a second layer at a thickness of 9 nm, and ZnO as a third layer at a thickness of 44.08 nm. The graph 300 includes a reflectance line 402 and a transmittance line 404. The visible spectrum 406 is from about 400 nm to about 730 nm. The infrared spectrum 408 is illustrated on graph 400 from about 750 to about 2500 nm. As illustrated, the average transmittance in the visible light range is about 95.62%. Further, the average reflectance in the infrared spectrum is about 61.75%.
Table 3 is a table of the reflectance and transmittance used to generate graph 400.









TABLE 3





Wavelength




(nm)
Reflectance
Transmittance

















250
29.36
45.88


260
25.58
49.84


270
22.08
53.22


280
19.67
56.04


290
17.34
59.84


300
14.33
65.64


310
13.34
75.33


320
14.92
80.20


330
16.65
81.12


340
16.25
81.37


350
14.88
83.06


360
13.38
84.92


370
11.88
86.88


380
10.04
88.59


390
8.45
90.04


400
7.05
91.30


410
5.91
92.47


420
4.94
93.48


430
4.12
94.36


440
3.43
95.10


450
2.85
95.75


460
2.29
96.28


470
1.84
96.72


480
1.46
97.09


490
1.14
97.40


500
0.86
97.66


510
0.63
97.83


520
0.43
97.96


530
0.26
98.06


540
0.14
98.12


550
0.05
98.13


560
0.01
98.11


570
0.00
98.05


580
0.05
97.95


590
0.13
97.80


600
0.26
97.61


610
0.46
97.31


620
0.71
96.96


630
1.02
96.56


640
1.39
96.09


650
1.82
95.56


660
2.28
95.05


670
2.79
94.49


680
3.37
93.87


690
4.00
93.18


700
4.69
92.45


710
5.44
91.66


720
6.24
90.82


730
7.08
89.95


740
7.97
89.02


750
8.90
88.07


760
9.81
87.09


770
10.75
86.09


780
11.72
85.07


790
12.70
84.03


800
13.95
82.75


810
15.17
81.48


820
16.22
80.39


830
17.27
79.30


840
18.34
78.20


850
19.39
77.10


860
20.37
76.12


870
21.36
75.13


880
22.34
74.15


890
23.34
73.16


900
24.34
72.16


910
25.21
71.29


920
26.09
70.41


930
26.98
69.53


940
27.86
68.66


950
28.73
67.79


960
29.35
67.09


970
29.98
66.39


980
30.59
65.70


990
31.18
65.03


1000
31.78
64.36


1010
32.71
63.37


1020
33.65
62.38


1030
34.57
61.41


1040
35.47
60.47


1050
36.36
59.53


1060
37.24
58.61


1070
38.13
57.67


1080
39.01
56.76


1090
39.85
55.88


1100
40.69
55.00


1110
41.52
54.14


1120
42.35
53.29


1130
43.15
52.46


1140
43.94
51.64


1150
44.71
50.84


1160
45.48
50.05


1170
46.24
49.27


1180
46.98
48.50


1190
47.71
47.75


1200
48.43
47.02


1210
49.14
46.29


1220
49.83
45.58


1230
50.52
44.89


1240
51.19
44.20


1250
51.85
43.53


1260
52.49
42.87


1270
53.13
42.22


1280
53.76
41.59


1290
54.37
40.97


1300
54.98
40.36


1310
55.56
39.77


1320
56.13
39.19


1330
56.69
38.62


1340
57.24
38.07


1350
57.79
37.52


1360
58.33
36.98


1370
58.85
36.45


1380
59.36
35.93


1390
59.87
35.43


1400
60.37
34.93


1410
60.86
34.44


1420
61.35
33.95


1430
61.82
33.48


1440
62.28
33.02


1450
62.74
32.56


1460
63.19
32.11


1470
63.63
31.67


1480
64.07
31.24


1490
64.50
30.82


1500
64.92
30.41


1510
65.33
30.00


1520
65.74
29.60


1530
66.14
29.20


1540
66.53
28.81


1550
66.91
28.44


1560
67.29
28.07


1570
67.67
27.70


1580
68.03
27.34


1590
68.39
26.99


1600
68.75
26.64


1610
69.10
26.30


1620
69.44
25.96


1630
69.78
25.64


1640
70.11
25.31


1650
70.44
25.00


1660
70.76
24.68


1670
71.07
24.38


1680
71.38
24.07


1690
71.69
23.78


1700
71.99
23.49


1710
72.29
23.20


1720
72.58
22.92


1730
72.86
22.65


1740
73.14
22.38


1750
73.42
22.11


1760
73.69
21.85


1770
73.96
21.59


1780
74.23
21.33


1790
74.49
21.08


1800
74.74
20.84


1810
75.00
20.60


1820
75.25
20.35


1830
75.49
20.12


1840
75.73
19.90


1850
75.96
19.68


1860
76.21
19.44


1870
76.43
19.22


1880
76.66
19.01


1890
76.88
18.81


1900
77.10
18.60


1910
77.32
18.38


1920
77.54
18.18


1930
77.74
17.98


1940
77.95
17.79


1950
78.15
17.60


1960
78.35
17.41


1970
78.55
17.22


1980
78.75
17.04


1990
78.94
16.86


2000
79.13
16.68


2010
79.27
16.51


2020
79.42
16.35


2030
79.56
16.19


2040
79.70
16.03


2050
79.84
15.87


2060
79.98
15.72


2070
80.12
15.56


2080
80.25
15.41


2090
80.38
15.26


2100
80.51
15.12


2110
80.64
14.98


2120
80.76
14.84


2130
80.88
14.71


2140
81.00
14.58


2150
81.12
14.45


2160
81.25
14.31


2170
81.37
14.16


2180
81.50
14.02


2190
81.62
13.89


2200
81.74
13.76


2210
81.84
13.65


2220
81.95
13.54


2230
82.06
13.41


2240
82.18
13.29


2250
82.28
13.18


2260
82.38
13.07


2270
82.48
12.96


2280
82.59
12.84


2290
82.71
12.71


2300
82.82
12.59


2310
82.93
12.47


2320
83.03
12.36


2330
83.13
12.25


2340
83.23
12.15


2350
83.33
12.04


2360
83.43
11.94


2370
83.52
11.84


2380
83.61
11.74


2390
83.70
11.65


2400
83.80
11.55


2410
83.88
11.46


2420
83.97
11.36


2430
84.06
11.28


2440
84.14
11.19


2450
84.22
11.11


2460
84.31
11.02


2470
84.39
10.93


2480
84.48
10.84


2490
84.56
10.76


2500
84.64
10.67









FIG. 5 is a graph 500 of the reflectance and transmittance for a dielectric thin film device with PET as the substrate, ITO as a first layer at a thickness of 130 nm, Al2O3 as a second layer at a thickness of 142.63 nm, TiO2 as a third layer at a thickness of 99.37 nm, Al2O3 as a fourth layer at a thickness of 144.67 nm, TiO2 as a fifth layer at a thickness of 97.42 nm, Al2O3 as a sixth layer at a thickness of 146.48 nm, TiO2 as a seventh layer at a thickness of 90.39, and Al2O3 as an eight layer at a thickness of 34.13. The graph 500 includes a reflectance line 502 and a transmittance line 504. The visible spectrum 506 is from about 380 nm to about 700 nm. The infrared spectrum 508 is illustrated on graph 400 from about 700 to about 2500 nm. As illustrated, the average transmittance in the visible light range is about 86.26%. Further, the average reflectance in the infrared spectrum is about 27.12%.
Table 4 is a table of the reflectance and transmittance used to generate graph 500.









TABLE 4





Wavelength




(nm)
Reflectance
Transmittance

















250
8.88
85.05


260
6.63
87.30


270
7.84
86.33


280
6.66
87.71


290
6.49
88.09


300
8.64
86.24


310
40.51
56.24


320
69.74
28.64


330
78.01
20.88


340
72.99
25.66


350
49.43
48.07


360
12.05
83.75


370
13.29
82.73


380
18.10
78.18


390
13.03
83.06


400
10.79
85.31


410
13.00
83.35


420
12.09
84.41


430
8.31
88.23


440
8.21
88.54


450
13.34
83.84


460
17.65
79.87


470
16.73
80.94


480
11.80
85.91


490
7.47
90.29


500
7.75
90.15


510
11.46
86.65


520
14.85
83.45


530
15.79
82.63


540
14.31
84.17


550
11.70
86.83


560
9.57
89.02


570
8.93
89.68


580
9.73
88.93


590
11.20
87.51


600
12.50
86.25


610
13.22
85.56


620
13.39
85.41


630
13.30
85.52


640
13.24
85.60


650
13.31
85.53


660
13.47
85.37


670
13.54
85.30


680
13.28
85.54


690
12.53
86.28


700
11.29
87.49


710
9.81
88.94


720
8.63
90.10


730
8.45
90.25


740
10.04
88.68


750
13.81
84.96


760
19.68
79.17


770
26.98
71.98


780
34.80
64.27


790
42.38
56.80


800
49.41
49.87


810
55.33
44.03


820
60.18
39.25


830
64.16
35.32


840
67.38
32.14


850
69.97
29.59


860
72.02
27.56


870
73.63
25.97


880
74.87
24.75


890
75.80
23.83


900
76.44
23.19


910
76.88
22.76


920
77.09
22.55


930
77.11
22.52


940
76.95
22.67


950
76.64
22.97


960
76.17
23.43


970
75.55
24.03


980
74.79
24.77


990
73.90
25.64


1000
72.85
26.66


1010
71.67
27.81


1020
70.33
29.11


1030
68.85
30.56


1040
67.23
32.14


1050
65.46
33.87


1060
63.54
35.74


1070
61.50
37.74


1080
59.32
39.86


1090
57.01
42.12


1100
54.58
44.49


1110
52.06
46.95


1120
49.47
49.49


1130
46.78
52.11


1140
44.06
54.78


1150
41.30
57.48


1160
38.54
60.17


1170
35.79
62.85


1180
33.08
65.49


1190
30.43
68.07


1200
27.87
70.56


1210
25.43
72.93


1220
23.11
75.18


1230
20.96
77.27


1240
18.96
79.21


1250
17.14
80.97


1260
15.51
82.55


1270
14.08
83.93


1280
12.82
85.14


1290
11.76
86.15


1300
10.88
87.01


1310
10.22
87.67


1320
9.73
88.16


1330
9.41
88.48


1340
9.25
88.65


1350
9.22
88.69


1360
9.32
88.60


1370
9.52
88.42


1380
9.80
88.15


1390
10.16
87.81


1400
10.58
87.40


1410
11.05
86.95


1420
11.55
86.47


1430
12.07
85.97


1440
12.61
85.44


1450
13.17
84.91


1460
13.71
84.38


1470
14.26
83.86


1480
14.80
83.34


1490
15.32
82.83


1500
15.85
82.32


1510
16.35
81.85


1520
16.83
81.39


1530
17.26
80.97


1540
17.68
80.58


1550
18.10
80.17


1560
18.51
79.78


1570
18.83
79.49


1580
19.16
79.17


1590
19.50
78.85


1600
19.75
78.61


1610
20.03
78.35


1620
20.26
78.14


1630
20.47
77.94


1640
20.66
77.77


1650
20.83
77.61


1660
20.98
77.48


1670
21.08
77.39


1680
21.18
77.30


1690
21.27
77.22


1700
21.34
77.17


1710
21.37
77.15


1720
21.42
77.11


1730
21.44
77.10


1740
21.44
77.11


1750
21.42
77.14


1760
21.40
77.18


1770
21.36
77.23


1780
21.30
77.30


1790
21.23
77.37


1800
21.16
77.45


1810
21.07
77.55


1820
20.94
77.68


1830
20.83
77.80


1840
20.78
77.86


1850
20.66
77.99


1860
20.47
78.18


1870
20.35
78.32


1880
20.22
78.45


1890
20.09
78.59


1900
19.93
78.75


1910
19.75
78.94


1920
19.58
79.11


1930
19.42
79.28


1940
19.26
79.45


1950
19.08
79.63


1960
18.91
79.81


1970
18.73
79.99


1980
18.54
80.18


1990
18.36
80.37


2000
18.17
80.57


2010
17.98
80.76


2020
17.79
80.95


2030
17.60
81.15


2040
17.41
81.34


2050
17.22
81.53


2060
17.03
81.72


2070
16.84
81.92


2080
16.65
82.11


2090
16.47
82.30


2100
16.28
82.49


2110
16.10
82.68


2120
15.91
82.86


2130
15.73
83.05


2140
15.54
83.24


2150
15.36
83.42


2160
15.18
83.60


2170
15.02
83.77


2180
14.85
83.94


2190
14.69
84.10


2200
14.52
84.27


2210
14.35
84.45


2220
14.18
84.62


2230
14.02
84.78


2240
13.87
84.93


2250
13.71
85.09


2260
13.56
85.25


2270
13.41
85.41


2280
13.27
85.54


2290
13.15
85.67


2300
13.02
85.79


2310
12.90
85.92


2320
12.77
86.05


2330
12.64
86.18


2340
12.52
86.30


2350
12.40
86.42


2360
12.29
86.54


2370
12.17
86.66


2380
12.06
86.77


2390
11.96
86.88


2400
11.86
86.98


2410
11.76
87.08


2420
11.66
87.18


2430
11.57
87.28


2440
11.48
87.37


2450
11.40
87.45


2460
11.33
87.53


2470
11.25
87.61


2480
11.18
87.68


2490
11.11
87.75


2500
11.05
87.81









Furthermore, using the technology described herein, it is anticipated that embodiments of infrared-control coated thin film devices can be created that will have even more advantageous transmittance and reflectance properties. For example, in an embodiment, an infrared-control coated thin film device will have greater than 70% visible light transmittance while maintaining greater than 70% reflectance. In another embodiment, an infrared-control coated thin film device may have greater than 75% visible light transmittance while maintaining greater than 75% reflectance. In another embodiment, an infrared-control coated thin film device may have greater than 80% visible light transmittance while maintaining greater than 80% reflectance. In another embodiment, an infrared-control coated thin film device may have greater than 85% visible light transmittance while maintaining greater than 85% reflectance. In another embodiment, an infrared-control coated thin film device may have greater than 90% visible light transmittance while maintaining greater than 90% reflectance. In another embodiment, an infrared-control coated thin film device may have greater than 95% visible light transmittance while maintaining greater than 95% reflectance. In other embodiments, transparency and reflectance need not be equal. For example, an infrared-control coated thin film device may have greater than 85% visible light transmittance while maintaining greater than 55% reflectance.
FIG. 6 illustrates a roll-to-roll system 600 for depositing one or more infrared controlling layers on a substrate. A roll-to-roll system allows the manufacture of multiple devices in a continuous or semi-continuous process. A roll-to-roll system is so named for having a web (e.g., a PET substrate) translate (i.e., move) from a starting roll, through a system, to another starting roll. During translation, one or more processes are performed on the web. At the end of the system, the web is wound or cut into individual devices. This allows for, in certain processes, a faster manufacturing time.
The system 600 causes translation of the web 602 housed on a unwind spool 604. Process chamber 606 deposits one or more infrared-controlling layers on to the web 602 to form a post-process web 608. The post-process web 608 is wound onto a wind spool 610.
Translation of the web through the system 600 may be accomplished in various ways. A guide track or other means may be used to mechanically support the translation of the web 602 through system 600. As illustrated spools 604 and 606 have mandrels 612 on which a web may be spooled. For example, a fully spooled mandrel may have 20′′ outside diameter and a 6′′ core, and be 1.2 meters wide. Various idler rollers 614 may guide the web 602 and the post process web 608. Idler rollers may be designed for removal for periodic cleaning. In embodiments, the idler roller surface roughness may be 8 micro-inch rms. Idler rollers may spin freely, and they may have low rotational inertia. Idler rollers may have active sensors to indicate positive motion.
The web 602 may translate through the system 600 at specified rate. In an embodiment, for example, the system 600 at a rate of 1 to 48 inches per minute. This speed may be set to be constant during processing or may vary as needed. Acceleration and deceleration of spools 604 and 610 may be controlled, which may help prevent slack in the spool. Tension of the web 602, may be set at 10-50 lbf for a 1 meter wide device or substrate.
Process chamber 606 is a chamber where one or more manufacturing techniques are used to deposit an infrared-control thin film layers. Processes in include physical vapor deposition, chemical vapor deposition, ion beam assisted evaporation, pulsed laser deposition, sputter deposition, and sol-gel processes.
In an embodiment, process chamber 606 includes a pulsed-energy microwave chemical vapor deposition process to form at least one layer, such as one or more infrared-controlling layers. In a pulsed-energy microwave chemical vapor deposition process, microwave energy is pulsed to ignite and maintain a plasma. It is believed that pulsing the microwave allows for the control of the rate of production of ions, the energy of ions, and the rate the ions strike a substrate or web. For certain pulse frequencies, this increases the deposition rate of material on a substrate at a given temperature while maintaining the quality of the deposited layer. Accordingly, lower temperatures may be used to achieve the same deposition rate. For example, the temperature of substrate may be kept at or below 250° C., 240° C., 230° C., 220° C., 210° C., or 200° C. during deposition, which allows for the use of substrates with lower melting points. Additionally, the rate of deposition may occur at a rate of greater than 50 angstroms per second, 60 angstroms per second, 70 angstroms per second, 80 angstroms per second, 90 angstroms per second, and 100 angstroms per second.
Though system 600 depicts only one process chamber, other embodiments may have more than one process chamber to deposit one or more infrared-control coated devices onto a web. Still, other embodiments include other process systems to further treat a web. For example, a first process chamber may use pulsed energy microwave plasma enhanced chemical vapor deposition. A second process chamber may use sputtering deposition. The sputtering chamber may deposit materials such as ITO.
Finished infrared-control coated devices may then be cut from the web by any suitable means. In alternative embodiments, a mechanical, hydraulic, or pneumatic press is employed. In such embodiments, formation of the post-process web 608 may occur in a semi-batch manner. A wind module 610 receives the post-process web 608. Wind module has a mandrel 612 designed to receive the post-process web 608.
FIG. 7 is an embodiment of a microwave plasma enhanced chemical vapor deposition chamber 700. As illustrated, FIG. 7 includes a process chamber 702 defined by process chamber walls 704, an inlet gas line 706, an outlet gas line 708, a plasma sheath 710, a substrate 712, a microwave wave guide 714, and a microwave generator 716. Temperature is controlled by a temperature control element 718.
The process chamber 702 is a chamber defined by chamber walls 704. The process chamber is generally configured to maintain an internal pressure. This pressure is determined in part by the inflow of gases from inlet gas line 706 and outlet gas line 708. The pressure and temperature in the process chamber 702 affects the material deposited on the substrate 712.
In an embodiment, non-reactive gases such as helium or argon flow in through inlet gas line 706. Additionally, a source gas, such as hexamethyldisiloxane (HMDSO), diethyl zinc (DEZ), trimethyl aluminum (TMA), etc., are pumped into the chamber through the inlet gas line 706. Gas exits the system from outlet gas line 708. Process conditions in process chamber 702 vary. In an embodiment, the process pressure ranges from 100-220 mTorr. In an embodiment, HMDSO and O2 are pumped into the chamber 708 at a ratio of HMDSO to O2 ranging from 10-80.
Ions produced in the plasma sheath 710 have an energy distribution. The energy distribution of the produced ions is dependent on, inter alia, the microwave frequency and pulse produced by microwave generator 716. Some of the source gas and/or its reactants will be deposited onto a substrate 712. In an embodiment, the source gas reacts with one or more other process gases and the resulting compound deposits onto the substrate 712. This reaction may occur at the surface of the substrate 712, above the substrate 712, and/or after material has been deposited on the substrate 712.
Deposited material will form structures, and those structures depend on the kinetic energy of ions created in the plasma sheath 710. For example, a layer of deposited material may be present on the substrate 712. The deposited material, given certain process conditions, will form a lattice or crystal structure. A lattice structure occurs when the deposited material is arranged in a substantially ordered manner. In other process conditions, however, a lattice structure will not form. Process conditions include the presences of impurities, the kinetic energy of the source gas at the time of colliding with substrate 712, and any other mechanisms that may control the transfer of kinetic energy of the deposited material. In embodiments, one such mechanism is to control the energy of ions through the use of the microwave generator 712.
A plasma 710 is ignited using microwave energy. The microwave wave generator 716 may have a power controller. The microwaves may be directed at plasma sheath 710 through use of a microwave guide 714. In an embodiment, the microwave generate will generate microwaves at a frequency of 2.54 GHz. In other embodiments, different microwave frequencies are used. The controller controls the power supplied to the microwave generator. In an embodiment, the microwave controller may pulse power to the microwave generator to form a pulsed waveform. In an embodiment, pulsing occurs at a rate of 100 Hz. In another embodiment, pulsing occurs at 10 Hz. Still in others, pulsing may occur at various cycles per second, including: 20 Hz, 30 Hz, 40 Hz, 50 Hz, 60 Hz, 70 Hz, 80 Hz, 90 Hz, 110 Hz, 120 Hz, 130 Hz, 140 Hz, and 150 Hz. Indeed, the cycle speed of the microwave may vary over the course of a given deposition.
A heating element 718 may be used to heat the process chamber. The heating element 718 may generate heat through any means now known or later developed. Accordingly, may be one of conductive, convective, or radiative means.
FIG. 8 is an embodiment of a method 800 for depositing infrared controlling layers on a substrate. Method 800 begins with select a substrate operation 802. The substrate may be flexible or rigid. For example, the substrate may be a material with a relatively low melting point compared to glass. In an embodiment, the substrate is one of polyethylene terephthalate (“PET”), polyethylene napthalate (PEN), polycarbonate, or transparent polymides, etc. In other embodiments, the substrate may be a transparent organic polymer or a transparent inorganic polymer. Still in other embodiments, the substrate is a ceramic or glass.
The method 800 continues to select deposition material operation 804. Selection of deposition material will determine the reflectance and transmittance properties of the infrared-control coated thin film device. In an embodiment, selection of deposition materials will determine the types of source gases that may be used.
The method the 800 continues to deposit material operation 806. In an embodiment, pulsed microwave-energy chemical vapor deposition is used. In other embodiments, deposit material operation 804 occurs using at least one of physical vapor deposition, chemical vapor deposition, thermal evaporation, pulsed laser deposition, sputter deposition, and sol-gel processes. In an embodiment, one or more of these processes occurs in series.
For example, deposit in deposit material operation 806, one or more layers may be deposited. For example, a first layer of SiO2 may be deposited using pulsed energy microwave plasma enhanced chemical vapor deposition. After the deposition of the SiO2, a layer of TiO2 may be deposited on the SiO2 layer. The TiO2 may be deposited using a variety of techniques listed above. In an embodiment, the TiO2 layer is deposited using microwave plasma enhanced chemical vapor deposition. The rate of pulsing of the microwave may be the same or different from the rate at which the microwave was pulsed during the deposition of the SiO2 layer.
FIGS. 9 through 16 represents technology related to sputtering deposition that may be used to create one or more layers of an infrared-control coated thin film device.
FIG. 9 represents prior art of a planar sputtering cathode system 900. Planar sputtering cathode system 900 includes a target 902, a cathode 904, a plasma sheath 906, a substrate 908, deposited material 910, a sputtered species 912, ions 914, and process gas particles 916.
In a planar sputtering cathode system 900, a target 902 may have a magnetic field applied to it. This magnetic field helps contain a plasma sheath 906 to the surface of a target 902 or near the surface of target 902. The magnetic field may confine electrons and secondary electrons to on and/or near the surface of a target. In an embodiment, the characteristics of the magnetic field affect the path of the electrons that travel around the surface of a target 902. The target 902 may be any material suitable for sputtering.
A cathode 904 has a voltage applied to it. In embodiments, a DC current is applied to a cathode 904. This DC current, which may create a 300V energy potential between the cathode 904 and the substrate 908, may be applied in order to ignite the plasma and generate ions 914. Some electrons 918 produced within the plasma sheath 906 have sufficient energy to meet the first ionization potential of the process gas particle 916. Consequently, some process gas particles 916 become positive ions 914.
Ions 914 produced in the plasma sheath 906 have an energy distribution. The energy distribution of the produced ions 914 is dependent on, inter alia, the current applied to the cathode 904, the waveform of that current, and the process gas used in the system.
Positive ions 914 accelerate toward a negatively charged cathode 904. The positive ions may collide with a target 902 and cause a sputtered species 912 to be ejected. Some of the sputtered species 912 will then be deposited onto a substrate 908. As such, sputtered species 912 may be the same material as both the target 902 and the deposited material 910. In other embodiments, the target material reacts with one or more process gases and the resulting compound deposits onto the substrate 908. This reaction may occur at the surface of the target 902, during the travel of sputtered species 912, and/or after material has been deposited on the substrate to form deposited material 910.
Deposited material 910 will form structures, and those structures depend on the kinetic energy of incoming sputtered species 912. For example, a layer of deposited material 910 may be present on the substrate 908. The deposited material 910, given certain process conditions, will form a lattice or crystal structure. A lattice structure occurs when the deposited material 910 is arranged in a substantially ordered manner. In other process conditions, however, a lattice structure will fail to form. Process conditions include the presences of impurities, the kinetic energy of the sputtered species 912 at the time of colliding with deposited material 910, and any other mechanisms that may control the transfer of kinetic energy to the deposited material 910. In embodiments, one such mechanism is to control the energy of ions 914. The relationship between kinetic energy and lattice structure is described more fully with reference to FIG. 10.
In general, the energy of sputtered species 912 is directly proportional to the kinetic energy of the ions 914. For example, some ions 914 collide with the target 902 and transfer energy to the target 902. As a result of this collision, some material of the target 902 is ejected and becomes a sputtered species 912. Thus, high-energy ions 914 striking a target 902 will cause sputtered species 912 to have a greater kinetic than low-energy ions 914. Additionally, upon striking the substrate 908, the sputtered species 912 transfers kinetic energy to the previously deposited material 910.
Another way ions 914 may affect the kinetic energy transferred to deposited material 910 is through ion 914 bombardment of the deposited material 910. For example, in instances where the polarity of the cathode is reversed, the positive ions 914 may accelerate toward a negatively charged substrate 908. In another embodiment, the substrate 908 does not hold a charge and the positive ions 914 accelerate toward a negatively charged area near a substrate 908. Ions 914 with a high kinetic energy that collide with deposited material 910 will transfer more kinetic energy than ions 914 with a lower kinetic energy. Furthermore, the more ions 914 that bombard deposited material 910, the more kinetic energy will transfer to the deposited material 910. Thus, the rate of ion 914 bombardment affects the kinetic energy transferred to deposited material 910.
With respect to FIG. 10, FIG. 10 illustrates a thin film 1000. In the embodiment shown, a substrate 1002 is illustrated with a thin film of deposited material 1004. Thin films with interstitial voids are known in the art. The deposited thin film 1000 is illustrated as having a substrate 1002, a deposited material 1004, interstitial voids 1006, and a sputtered species 1008.
For certain thin films, it may be desirous to remove or limit the number of interstitial voids 1006 that may form during deposition. For example, interstitial voids increase the electrical resistivity of thin films for certain materials. Controlling the transfer of kinetic energy to deposited material 1004 may limit the number of interstitial voids 1006 that form during deposition, and thus reduce the electrical resistivity of the thin film.
For certain deposited materials 1004, interstitial voids 1006 occur when a target material fails to have sufficient kinetic energy to meet or overcome the Schwoebel-Ehrlich barrier. Failure to meet the Schwoebel-Ehrlich barrier causes deposited material 1004 to form sloping regions 1010. Sloping regions 1010 tend to cause interstitial voids 1006. On the other hand, deposited material 1004 that has sufficient energy to overcome the Schwoebel-Ehrlich barrier may form a surface with a high surface symmetry. That is, the deposited material 1004 will form less sloping regions and arrange more evenly across the surface of the substrate 1002. As such, transfer of kinetic energy to a deposited material 1004 may allow the deposited material 1004 to have a sufficient energy to overcome the Schwoebel-Ehrlich barrier.
Additionally, it may also be desirous to limit the amount of kinetic energy transferred because too much kinetic energy transfer may damage the fidelity of the deposited material's 1004 lattice structure. Damaging the lattice structure may also increase the electrical resistivity of a thin film.
Controlling the transfer of kinetic energy may occur by controlling the kinetic energy of incoming sputtered species 1008. Controlling the transfer of energy may also occur through controlling ion kinetic energy and the rate of ion bombardment. Energy transfer to a deposited material is discussed further with reference to FIG. 9.
As such, it may be desirable to have an energy waveform applied to a cathode that can create ions at an appropriate rate and an appropriate energy for generating thin films with a targeted electrical resistance. This waveform will be referred to as a finely tuned waveform.
With reference to FIGS. 11 and 12, FIG. 11 illustrates the prior art of an RF waveform super positioned on a pulsed DC waveform 1100. FIG. 12, which is not prior art, illustrates a composite waveform 1200 that combines RF super positioned on pulsed-DC with a reverse voltage limiting threshold. Waveform 1100 and composite waveform 1200 have a pulsed-DC waveform 1102 and an RF waveform 1104. Composite waveform 1200 may be applied to a cathode of a sputtering deposition process in order to adjust the energy of the plasma.
Additionally the pulsed-DC waveform 1102 includes a plasma ignition portion 1106, a steady-state portion 1108, a reverse DC voltage portion 1110, and a pulsed-DC termination point 1114.
In an embodiment, the application of waveform 1100 or composite waveform 1200 to a cathode ignites a plasma in a sputtering deposition chamber. The plasma ignition occurs contemporaneous with a plasma ignition portion 1106. In another embodiment, the application of an RF waveform 1104 causes a plasma to ignite.
During plasma ignition, ions are generated. When a waveform 1100 or a composite waveform 1200 is applied to a cathode of a sputtering deposition chamber, generation of positive ions continues through the duration of a steady-state portion 1108. The positive charge of these ions causes the ions to propel toward a negatively charged cathode. The resulting collision with the target propels target material toward a substrate for deposition. The steady-state portion 1108 may have a voltage that is set at −50V, −60V, −70V, −80V, −90V, −100V, −110V, −120V, −130V, −140V, −150V, −160V, −170V, −180V, −190V, −200V, −210V, −220V, −230V, −240V, −250V, −260V, −270V, −280V, −290V, −300V, −310V, −320V, −330V, −340V, −350V, −360V, −370V, −380V, −390V, −400V, −410V, −420V, −430V, −440V, −450V, −460V, −470V, −480V, −490V, and −500V.
In the waveform 1100 and composite waveform 1200 shown, a reverse DC voltage portion 1110 occurs after steady-state portion 1108. When applied to a cathode, the reverse DC voltage portion 1110 changes the polarity of the cathode from negative to positive.
As shown, waveform 1100 and composite waveform 1200 have an RF waveform 1104 superimposed on the pulsed-DC waveform 1102. An RF waveform has an RF initiation point 1116, an amplitude 1118, a frequency 1120, and an RF application duration 1122. As illustrated, the waveforms 1100 and 1200 have an RF power termination point 1124.
In embodiments, an RF initiation point 1116 may occur at or near the same time as the plasma ignition portion 1106. When the waveform 1100 or waveform 1200 is applied to a cathode, RF initiation point 1116 marks the initiation of the application of the RF waveform 1104 to a cathode of a sputtering deposition chamber. When applying RF waveform 1104 to a cathode, varying the frequency 1120 and the amplitude 1118 of the RF waveform 1104 will generate ions with certain energy distributions. Furthermore, the density of ions created in a plasma sheath is directly proportional to the frequency 1120. For example, at 13.56 mhz an RF waveform 1104 may create ions at a faster rate than a lower frequency. Ion generation occurs during RF application duration 1122 until an RF power termination point 1124. RF power termination point 1124 may occur sometime before a reverse DC voltage portion 1110. Ensuring that the RF power termination point 1124 occurs before a reverse DC voltage portion 1110 may be accomplished by various analog and digital control techniques, or some combination of the two techniques.
Alternatively, RF is applied continuously until the final waveform cycle. In this embodiment, the RF is applied continuously through all stages of the pulsed-DC waveform 1102.
A reverse DC voltage portion 1110 may occur by design or may be caused intrinsically by shutting off a DC power supply. When applied to a cathode, the reverse DC voltage portion 1110 reverses the polarity of the cathode from negative to positive. When this reversal occurs in a sputtering deposition chamber, the positive ions will accelerate toward the now negatively charged substrate (or a negatively charged area near the substrate). This depletes the ion density of the plasma sheath and substantially halts the deposition of sputtered species. In the prior art waveform 1100, the kinetic energy of the ions striking the substrate is directly proportional to the magnitude of the reverse DC voltage portion 1110.
In embodiments, it may be desirous to limit the magnitude of the reverse voltage. Composite waveform 1200 includes a reverse voltage threshold 1212. This limits the magnitude of the reverse voltage limiting portion. Limiting the magnitude of the reverse voltage limits the kinetic energy of the ions accelerating toward the substrate during a reverse DC voltage portion 1110.
Limiting the reverse voltage may be accomplished through electronic devices along with analog and digital controllers. In some embodiments where the target is non-metallic, a reverse voltage limiting may interfere with the RF waveform. As described in greater detail below, the systems and methods disclosed herein account for this and prevent interference with the RF waveform while still allowing the reverse DC voltage to be limited.
Application of the reverse voltage threshold 1212 may be depend on the specific sputtering environment. For example, in an embodiment where the process gas is Ar, and the deposition material is transparent conductive oxide (“TCO”), a reverse DC voltage portion 1110 may last for between 0.5 and 10 mircoseconds. In embodiments, the reverse DC voltage portion lasts for a microsecond. Additionally, a reverse voltage threshold 1112 may be set between 100 and 300 volts.
Furthermore, the composite waveform 1200 may be applied at a 10 kHz, 20 kHz, 30 kHz, 40 kHz, 50 kHz, 60 kHz, 70 kHz, 80 kHz, 90 kHz, 100 kHz, 110 kHz, 120 kHz, 130 kHz, 140 kHz, 150 kHz, 160 kHz, 170 kHz, 180 kHz, 190 kHz, 200 kHz, 210 kHz, 220 kHz, 230 kHz, 240 kHz, 250 kHz, 260 kHz, 270 kHz, 280 kHz, 290 kHz, 300 kHz, 310 kHz, 320 kHz, 330 kHz, 340 kHz, 350 kHz, 360 kHz, 370 kHz, 380 kHz, 390 kHz, 400 kHz, 410 kHz, 420 kHz, 430 kHz, 440 kHz, 450 kHz, 460 kHz, 470 kHz, 480 kHz, 490 kHz, or 500 kHz.
As shown, rest period 1126 is present in waveform 1100 and composite waveform 1200. If applied to a cathode, rest period 1126 represents the time in which no pulsed-DC power is supplied to the cathode. The rest period 1126 is defined as the time between the termination of the application of a DC pulse and the next application of a DC pulse. A rest period may not be present or may be of a short or long duration relative to the DC pulse duration.
A cycle of a waveform 1100 or waveform 1200 is calculated by summing the time from the first application of power to the cathode until the end of a rest period 1126.
FIG. 13 illustrates the expected resistivity properties of thin films created when a waveform 1100 is applied to a cathode. The y-axis of the graph illustrates the minimum resistivity μOhm*cm. The x-axis represents the frequency at which the DC pulse would be applied to a cathode of a sputtering deposition chamber. Line 1302 illustrates the resistivity of a thin-film that may be produced by applying an embodiment waveform 1100, i.e., an RF waveform superimposed on pulsed-DC waveform to a cathode of a sputtering deposition chamber.
Line 1302 may be understood as having three frequency ranges. In the first range, the minimum resistivity of the thin film decreases in a decreasing resistivity range 1308. As illustrated, line 1302 illustrates the resistivity decreasing from  ̃185 to  ̃148 μOhm*cm over the decreasing resistivity range 1308. This corresponds to a frequency of 0 to  ̃100 kHz DC-pulsed. At a steady-state point 1310 the resistivity of the thin film no longer decreases. As illustrated, the steady-state point is  ̃100 kHz. The steady-state point 1310 marks the start of a steady-state range 1312. In a steady-state range 1312, the resistivity of the produced thin-film does not vary substantially with varying pulsed-DC frequencies. As illustrated, line 1302 has a steady-state 1312 that corresponds to a frequency range from 100 kHz to  ̃200 kHz. In some embodiments, at an inflection point 1314 the resistivity of the thin film begins to increase. As illustrated, the inflection point 1314 for line 1302 corresponds to a frequency of  ̃200 kHz. After the inflection point 1314, an increasing resistivity range 1316 may be present. In increasing resistivity range 1316, the resistivity of the produced thin film increases as frequency of the pulsed-DC increases. As illustrated, line 1302 has an increasing resistivity range 1316 that corresponds to a frequency of  ̃200 kHz to at least 300 kHz.
FIG. 14 illustrates the expected resistivity properties of thin films created when a composite waveform 1200 is applied to a cathode. The y-axis of the graph illustrates the minimum resistivity μOhm*cm. The x-axis represents the frequency at which the DC pulse would be applied to a cathode of a sputtering deposition chamber. Line 1404 illustrates the resistivity of a thin-film that may be produced by applying an embodiment of a composite waveform 1200, i.e., an RF waveform superimposed on pulsed-DC waveform combined with reverse voltage limiting. Additionally, line 1406 illustrates the resistivity of a thin-film produced that may be produced by applying an alternative embodiment of a composite waveform 1200.
Line 604 may be understood as having two areas, a decreasing resistivity range 1408 and steady-state range 1412. Additionally, line 1406 may be understood as having two areas, a decreasing resistivity range 1414 and a steady-state range 1416. As illustrated, line 1404 has a decreasing resistivity range 1412 that is greater than the decreasing resistivity range 1414 of line 1406. In embodiments, this may be because the composite waveform 1200 that produced the results illustrated by line 1406 has a lower reverse voltage threshold than the composite waveform 1200 that produced the results illustrated by line 1404.
As illustrated, lines 1404 and lines 1406 have no increasing resistivity range. This may occur because the composite waveforms 1200 used to produce lines 1404 and 1408 have a reverse limiting voltage threshold. This reverse threshold may ensure that ions that strike the previously deposited material have a sufficiently low kinetic energy.
FIG. 15 illustrates a method 1500 of applying an RF waveform super positioned on a pulsed DC waveform combined with reverse voltage threshold to a cathode of a sputtering deposition process. The method 1500 includes an apply a pulsed DC waveform to a cathode operation 1502. The method 1500 also includes an apply an RF waveform to a cathode operation 1504.
As illustrated, method 1500 begins with apply a pulsed DC waveform to a cathode operation 1502. In other embodiments, the method 1500 begins with an apply an RF waveform to a cathode operation 1504. Still in other embodiments, the operations 1502 and 1504 may occur at the same time.
FIG. 15A illustrates the apply a pulsed DC waveform to a cathode operation 1502. The applying a pulsed DC waveform operation 1502 includes an initiate plasma operation 1502A, apply a controlled voltage operation 1502B, a reverse the DC voltage operation 1502C, a limit the reverse voltage operation 1502D, and a terminate pulsed-DC operation 1502E.
The apply a DC waveform to a cathode operation 1502 begins with an initiate plasma operation 1502A. Initiate plasma operation 1502A may result in a negative voltage spike for some period of time. For example, the spike lasts for between 0.5 to 10 microseconds in embodiments. In other embodiments, there is no spike, and an initiate plasma operation 1502A merely marks the point at which a pulse DC waveform is first applied to a cathode.
The apply a DC waveform to a cathode operation next proceeds to an apply a controlled voltage operation 1502B to a cathode operation. This operation results in a DC being applied for some time period at a substantially fixed voltage. For example, a DC waveform may have a controlled voltage operation 1502B between −100V and −300V.
Next, operation 1502 proceeds to a reverse the DC voltage operation 1502C. In an embodiment, reverse the DC voltage operation 1502C causes the voltage to be reversed from negative to positive. As mentioned above, the reverse the DC voltage operation 1502C may be an active operation as shown or may be a natural result of the termination of the operation 1502B. In an embodiment where the original voltage was positive, the reverse the DC voltage operation 1502C causes the voltage to be reversed from positive to negative. In an embodiment, the reverse DC voltage operation 1502C causes the DC voltage to go to between +50 and +400V absent a limit the reverse voltage operation 1502D described below.
A limit the reverse voltage operation 1502D limits the degree to which the reverse the DC voltage operation 1502C can reverse the voltage applied to the cathode. In embodiments, the limit the reverse voltage operation 1502D causes the reverse voltage to be limited to one of the following voltages +50V, +60V, +70V, +80V, +90V, +100V, +110V, +120V, +130V, +140V, +150V, +160V, +170V, +180V, +190V, +200V, +210V, +220V, +230V, +240V, +250V, +260V, +270V, +280V, +290V, +300V, +310V, +320V, +330V, +340V, +350V, +360V, +370V, +380V, +390V, and +400V. A terminate pulsed-DC operation 1502E ends the application of the reverse voltage to a cathode. This may occur naturally as a final result of terminating operation 1502B.
The reverse voltage limiting operation 1502D is presented here as a separate step, although the reader will recognize that the reverse voltage operation 1502C, the limiting operation 1502D and the DC pulse termination operation 1502E may all occur at the same or substantially the same time and may be, in effect, a single operation. In an embodiment in which the reverse voltage is a transient effect caused by the termination of the DC pulse, the limiting operation 1502D is achieved by the simultaneous activation of reverse voltage limiting electronics that prevent the reverse voltage from exceeding the set threshold.
In embodiments where the target is non-metallic, the timed activation of the electronics prevents interference with the applied RF waveform or other desired transient elements of the waveform, which would be detrimentally affected if the limiting electronics were active at all times. In an alternative embodiment, although difficult in practice using currently available technology, the entire waveform may be controlled by software so that the exact desired waveform is delivered at the chamber without the need to rely on inherent properties of the hardware to intrinsically create some or all of the waveform (e.g., the reverse voltage).
FIG. 15B illustrates an apply an RF waveform operation 1504. In an embodiment, the apply an RF waveform operation 1504 includes a determine an RF frequency and amplitude operation 1504A, an initiate an RF application 1504B, an apply an RF operation 1504C, and a terminate an RF application 1504D.
Apply an RF waveform operation 1504 begins with a determine an RF frequency and amplitude operation 1504A.
Next an initiate an RF application operation 1504B initiates the application of an RF waveform to a cathode. The application of the RF waveform to a cathode continues through apply an RF waveform operation 1504C. Apply an RF waveform operation 1504C may last for a duration of the apply a controlled voltage operation 1502B. Alternatively the apply the RF waveform operation 1504C may last for the entire duration of all cycles of pulsed-DC waveform.
A terminate an RF application operation 1504D stops the application of an RF waveform to a cathode. In embodiments, the terminate an RF application operation occurs before the limit the reverse voltage operation 1502D.
FIG. 16 illustrates a system to apply an RF and pulsed DC waveform combined with reverse voltage threshold to a cathode of a sputtering deposition process 1600. As illustrated, FIG. 16 includes a DC power supply 1602, an RF power supply 1604, a reverse voltage limiting device 1606, and a control circuit 1608. The DC power supply 1602 applies a pulsed-DC waveform 1602 to a cathode of a sputtering deposition chamber. The RF power supply 1604 applies an RF waveform 1104 to a cathode. A reverse voltage limiting device 1606 limits the reverse voltage of a pulsed-DC waveform 1102. The reverse voltage limiting device 1606 may include any suitable signal modification circuits such as capacitors, inductors, selected low-pass or band-pass filters or other electronics as needed to achieve the desired responsiveness and voltage limiting for the particular application. Additionally, a control circuit 1608 controls the interaction and timing of the DC power supply 1602, the RF power supply 1604, and the activation of the reverse voltage limiting device 1606. For example, the control circuit 1608 may ensure that the RF power supply 1604 turns off prior to the DC power supply 1602 applying a reverse DC voltage portion 1110 to a cathode of a sputtering process.
It will be clear that the systems and methods described herein are well adapted to attain the ends and advantages mentioned as well as those inherent therein. Those skilled in the art will recognize that the methods and systems within this specification may be implemented in many manners and as such is not to be limited by the foregoing exemplified embodiments and examples. In other words, functional elements being performed by a single or multiple components and individual functions can be distributed among different components. In this regard, any number of the features of the different embodiments described herein may be combined into one single embodiment and alternate embodiments having fewer than or more than all of the features herein described as possible.
While various embodiments have been described for purposes of this disclosure, various changes and modifications may be made which are well within the scope of the disclosed methods. Numerous other changes may be made which will readily suggest themselves to those skilled in the art and which are encompassed in the spirit of the disclosure.

## Claims

1. A method comprising:
selecting polyethylene terephthalate as a substrate, wherein the substrate has a melting point of less than 250° C.;
selecting one or more dielectric materials to be deposited onto the substrate;
depositing, in a process chamber with an average temperature below 240° C., the one or more dielectric materials onto the substrate to form an infrared controlling thin film device, wherein the depositing occurs at rate greater than 50 angstroms per second using microwave energy chemical vapor deposition; and
pulsing a microwave at a rate of 100 Hz during the depositing.

2. The method of claim 1, further wherein the infrared controlling thin film device has an average infrared reflectance that is above 85%, and has an average visible transmittance of above 85%.

3. The method of claim 1, further wherein the infrared controlling thin film device has an average infrared reflectance that is above 85%, and the device has an average visible transmittance of above 90%.

4. The method of claim 1, wherein the one or more dielectric materials are a transparent conductive oxide.

5. The method of claim 4, wherein the transparent conductive oxide is selected from the group consisting of: gallium doped zinc oxide (GZO), aluminum doped zinc oxide (AZO), Indium doped tin oxide (ITO), and fluorine doped tin oxide.