CA2126674A1 - Exothermic reflexible glass, exothermic transparent glass and process of manufacturing them - Google Patents

Abstract

The present invention relates to a process of manufacturing an exothermic reflexible glass which can emit heat of over 50 ·C by coating the matrix glass with a thin layer of such metals as Cr, Ni, Au, Ag, Al, Cu by use of the sputtering technique for plasma, and a process of manufacturing an exothermic transparent glass whose surface temperature can be adjusted to a desired degree by means of connecting to a power source, after coating the matrix glass with a thin layer of transparent material of indium-tin oxide by use of the reactive sputtering technique and also to the glass produced respectively by these processes.

Description

WO 93/13239 PCl /KR92/OOOX I

2~ 2~7~

Exothex~ic Reflexible Glass. ~xothen~ic Transparent Glass and Process of anufacturing the . E~C3I;~lIND I~e INVENIION
- ~` Eield of Invention This Invention relates to the exothermic reflexible ~lass and exothermic transparent glass as well as to a process for the manufacture of them, whose :: :
~ surface temperature can be adjusted at vill by means of coating non-conductive . . .
~ glass either with reflexibilîty-conductive material or transparency-conductive , material by use of the sputterin~ technique generally used for plasma.
10~ DescrîPtion of Prior Art The technique of vacuum evaporation by sputtering, the very technique of manufacturîng exothexmic reflexible glass and exothenmic transparent glass here, is performed by a direct evaporation of the m~terial to be evaporated în vacuum through colliding ionized inert ~as into the surface of the target, that is, ionization of the inert gas takes place in the area of abnormal glow dîscharge and the thus ionized ~as, under the influence of the electric field, is made to beat the surface of a cathode. Thus, in the sputtering technîque, the target is used as the cathode and the vacuum container or the matrix, as the anode.
A simplest diode planar sputterin~ technique is shown in Fîg. 1, wherein a low pressure electric discharge takes place between the target(3), whîch is used as the cathode, and the anode. The pressure of the inert ~as in co~mon use should, for the purpose of maintaînin8 electrîc discharge, be over 5 X 10-3 torr, the working pressure ranging from 2 X 10-2 torr to 10~~ torr. The electric pressu M
. ~

applicable to the cathode can be varied from hundreds of volts to thousands of W O 93/13239 PC~r/K R92/00081 2t`~6Ç~ 2 volts. while the distance between the cathode and the matrix(vacuum container), the anode. is so near as about 5cm. The velocity of vacuum evaporation bein~
about 100 A/min, it is decided according to the energy and quantity of the ion being shot out. That is. the velocity of vacuum evaporation can be increased by raising the electric pressure and restricted by the decrease of the ionized cross section.
However,~ even though the ionized electric current can be increased by added pressure of incrt gas. ~the velocity of-vacu o ev~poration can rather be decreased in an effect of dispersion of the gas. Thus. the optimun condition as to the lO~ velocity~of the vacuum evaporation will have to be determined only through repeated experiments.
To see the basic idea of the sputtering it is known that when a certain pressure and electric tension are applied to a target(3). which exists within a ;vacu o container, plasma(4) is given rise to around the target and the positive - 15 -ions existing in the area of the electric discharge come to beat the surface of . ~
the target by virtue of electric forces. At this time the kinetic energy of the positive ions is transferred to the atoms which exist on the surface of target, and if this energy is stron~er than the bonding energy of the atom which are beaten, the atoms of the target are emitted.
The disadvantage of the sputtering technique lies in the very slow velocity in the coating formation. and the resultant low productivity. when a diode process is adopted. To solYe the above problems the triode system has been invented.
which has~a third electrode~for control of both the source of thermion emission.
and ~the~ flow~of the ~emitted ther ion is added to the diode system. where a W O 93/13239 2 ~ 4 pc~r/K Rg2/0008 tungsten filament is used as the source of emission for the thermions.
~ hen a triode system is adopted the velocity of vacuum evaporation can be increased, because it is possible to increase the concentration of plasma by the emission of thermions. When the concentration of the electrons in plasma is increased by emission of thermions, the probability of ionization is heightened by brisk action of electrons, the number of ions that beat the target is increased, and thus the velocity of vacuum evaporation is accelerated.
Besides the way of increasing the concentration of the plasma by supplying electrons there is another way of increasing the probability of ionization, that 1 o is, by means~of controlling the action of electrons with the use of magnetism.
`The sputtering vith the use of magnetism results in N and S electrodes at the back of the target changing the action of electrons from rectilinear to spiral.
Thus the probability of electrons to hit neutral atoms and others under the m ~~ sàEe pressure increases as the distance of electrons' movement is increased, and 15 ~by hei~htening the probability of ionization a greater velocity for vacuum evaporation is obtained. Fig. 2(A)~B) show the structure of the target. wherein the highest probability of ionization is to be seen at the point at which a line of magnetic force intersects another perpendicularly, showing a regional sputtering taking place forming a belt of high plasma concentration.
20 SUnnnRY Q~ IEE INVeNIIoN
The present invention is intended to provide both the process of manufacturing exothermic reflexible glass by coating any such metals as Cr, Ni, Au, Ag, Al, Cu over the~surface of 61ass by the technique of magnetic sputtering as given above, ~ and the process of ~anufacturing exothermic transparent glass by creating a layer .- ~

,~ , .

,: ' ::
;, . ~

W O 93/13239 pc~r/KR92/ooo81 2 .t 2 6 ~ 7 L~

o~ oxidized coating with In(90~)-Sn(10%) alloy in a vacuum container.
Also the present invention is intended to provide both exothermic reflexible glass and exothermic transparent glass prepared by the above processes.
DESCRIPIION OF I~E DRA~INGS
Fi~. 1 is a sketch of the diode planar sputterin~ apparatus of the present invention.
, ~
Eig. 2(A) and (B) are sketches to show the structure of a tar~et for the ~N~ ,` sputtering.
Eig. 3 is a graph showing the different transparencies of the respective ITO
and Au thin coating test pieces on glass of different times spent on vacuu~
evaporation.
1 0~ Fig.~4 is a graph showing the different resistivilities of the respective ITO
~, ~
and Au thin coating test pieces of different times spent cn vacuum evaporation.
Figs. 5(A) and (B) atd graphs~showin6 the surface temperatures of ITO and Au thin coatin~s of 6.000 A and 400 A thicknesses. respectively.
Fig. 6 shows results of the XRD analysis of ITO test piece whose FO2/PAr value :~
is 0.43.
Indices 1..... gas inlet. 2.... power source.
~, 3..... target, 4.... plasma.
5,11.. ...substrate, 6.... pumping system, ::
7..... chamber. 12... .electron.
13.... .argont 14... .atom sputtered.
15.... .target, 16... .anode.
17.... .cathode. 18... .ma~netic field lines.
: ~

: : ~, W O 93/13239 PCl`/KR92/00081 212~4 l9substrate carrier.
DEIAILED DESCRIPIION OP I~e INVENIION
., .
In the present invention the direct current supplied by the DC power supply source was used and, as shown in Eig. 2, magnetron was attached to the back of S the target to raise the velocity of vacuum evaporation up to 1,000 A/min.
Eor the target an experimental item of 75mm in diameter and 5mm in thickness vas used, and in the case of Ni a thin coating was formed on the target whose .. ~
-~ ~ ' thickness was adjusted to lmm - 1.5mm due to its propensity for ~agnetizing by ; magnetrons.
In the case of such metals as Cr, Ni, and Cu the density of the electric power applied to them is 11.3W/cm3, and at the initial vacuity of 1 X 10-5 torr Ar ~as of purity 99.995Z was introduced for generation of plasma at the working pressure ~ .~
of 6 X 10-3 torr to produce reflexible glass. In the case of such metals as Au, Ag, and Al the density of the electric power was lowered to 6.8W/cm3 because under same conditions, the velocity of vacuum evaporation of these is greater than that of Cr, Ni, or Cu.
The glass used as the matrix was 2mm thick, of 130mm respectively in length and breadth. lt was placed under a process of cleansing with aloohol, distilled water, and aceton in that order, drying in an oven of 200~C for 10 minutes and puttin~ inside the sputter chamber, and then over 1,000 A thick coating was formed over ItS surface by the sputtering process. Then, when electric wires were attached by silver paste to the reflexible glass made by the above method ., ~,~,, electric power of about 0.06~/cm3 was supplied, it was found that a temperature of over 50~C was obtained on the density of the electric power and a desired , ~

.,~ ~. -w O 93/13239 pc~r/KR92/oooxl 212~ 4 6 temperature on the surface was obtained without difficulty.
Exothermic transparent glass is, unlike exothermic reflexible glass. made by coating glass with transparent oxide instead of usin~ any single metal, and in the present invention a tar~et of In(90~)-Sn(10%) was used for production of S exothermic transparent glass, and indium-tin oxide(ITO) was synthesized under the mixture of Ar and 02 for formation of the oxide. The specific feature of this material is that even when its thickness is 1,000 A it can allow penetration of ht by more than 80% so that it can be made wide~use of in production of the liquid crystal for- TV or other liquid crystal display systems. Hence the extensive study of this material has been made recently.
Then indium-tin oxide(ITO) in the present invention is made through the reactional process of DC magnetron, and what is important at this time is the ratio of Ar and 02 ~as in the mixture. If the ratio of 02 iS lower than the preferable ratio, the desired oxide is not produced, while if it is higher than that, the transparency decreases and the transparent conductive coating is not obtained. Thereupon in the present invention, using a mass flow meter manufactured by a US company MRS, the flow of Ar gas uas adjusted to 100 SCCM and the flow of 02 gas to 30-98 SCCM, resulting in formation of a transparent conductive material of good quality, while settin~ the flow o Ar gas at 100 SCCM
and 02 ~as at 43 SCCM is more preferable.
The density of the electric power can be 1.5 - 8.0W/cm3 and if it is higher, it takes short time for the vacuum evaporation and if it is lower, it takes lon~
time for it. It is more desirable to set the density of the power at 2.26W/cm3 and the time at 6.5 minutes.

W O 93/l3239 21 2 6 5 7 4 P(~r/K R92/00081 The experimental conditions for said indium-tin oxide(IT0) are given in Table 1 below:
TABLE 1. ExPerimental Conditions for IT0 Vacuum Eva w ration Coatin~ material Process Parameter IT0 Reactive Power density : 1.5 - 8.0W/cm3 sputtering ~orking pressure : 6 X 10-3 ~bar Sputterin~ time : 0.5, 1, 2, 3, 4, 5, 6.5, 8, 10, 12.5, 15 and 20 minutes F02/FAr = 0, 0.35, 0.43, 0.5. 0.7, 0.92, 0.98 The ~reatest factor that affects the transparency and conductivity at the time : 5~ of production of the I10 thin coating is the partial pressure of 02. and when the flow of the~neutral Ar gas supplied for reactive sputtering was indicated by EAr t that of 02 by E02, when the value of FO2/EAr was 0.39 or lower a coating of very good conductivity but of very bad transparency was formed, while when the value was 0.45 or more the transparency was fine but the conductivity fell to M Q
/Gm(mega Q/cm). When the value of EOz/EAr was 0.43 it was possible to form a coating fitting the purpose of the present invention, and the velocity of the formation of the coating at the time was ~easured about 1,200 A /min.
Among the materials which have so far been widely used in production of thin coating layers is Au with the best conductivity, and in the present invention Au 1~ vas vacuum evaporated on glass~by the sputtering technique in order to compare it with an I D thin coating layer, when the speed of the fonmation of the coating was set at 40 A /sec. With Cr, Al, Ni, and Cu coating it was found practically , ~ ~
~ impossible to produce a thin coating of such conductivity and transparency as W O 93/13239 PC~r/K R92/00081 2.t266~ 8 will justify commercial production. but yet it was also possible to use them in production of conductive reflexible glass by means of increasing the tickness of the coating layers.
;Fig. 3 is a ~raph to show the different transparencies of the ITO and Au thin s coating layers obtained by varied times of vacuum evaporation. In the case of:
~;the ITO thin coating layer the penetration of light was about 80% when the thin ~ ~coating layer's thickness was 0.8~um(vacuum evaporation by sputtering for 6.5 -ainutes), and the transparency gradually decreased as the layer's thickness increased, falling to 40% when the thickness was about 2.4~lm(vacuum evaporation by sputtering for 20 minutes). On the contrary. in the case of the thin coating iarer ~of Au. the transparency measured 65% with the thickness 200 A(vacuum evaporation by the sputtering for 5 seconds) and as the time for the vacuum evaporation increased the transparency rapidly fell.
The resistive features were measured by calculating the current, as lOV
electric pressure was applied, after placing a Cu electrode each on both ends of an experimental piece of 72mm by 23mm size. Those showing resistance by M Q
units were measured with ordinary multi meters, the resultsi being shown in Fi~.
4. Fig. 4(A) carries a graph showing the resistive features of an ITO
experimental piece, different as the time for vacuum evaporation by- the ; 20 sputtering varied. The value of resistance was 400 Q when the time for vacuum evaporation by the sputtering WdS two ~inutes. but it declined rapidly as the ti~e was protracted to fall, for instance, as low as about 20 Q when the time was 10 minutes(1.2~um).
,~
~Eig. 4(8) carries a graph of the resistive features in the case of an Au WO 93/13239 PCr/KR92/00081 212~6~

coating layer, and in this, too, as in the case of the IT0 coating layer, the resistance rapidly declined with rapidity as the time for vaauum evaporation by the sputterin~ increased.
Ihe object of the present invention is to develop a aaterial as well as the software for the manufacture of conductive and transparent glass for use in auto~obiles, and since the change of temperatures of the experimental piece makes, as well as its transparency, a most i~portant part of the present invention.~ the temperatures should be measured acculately. Hence, on the surface of the~experimental piece a K-type thermo-electric band was attached by means of IO silver paste and~ it was connected to a X-Y recorder in order to ~easure continuously the te~peratures of the surface of the experimental piece varying at the change of~the elec *ic ~ressure and the electric current.
Pig. 5(A) is a ~raph sho~ing the measured surfsce temperatures of the IT0 thin coating layers of 6,000 A in thickness, drawing a curve of (a), (b), (c), (d), and (e)~ for 0.775W(SV X O.lSSA), 1.512W(7V X 0.216A). 2.466W(9V X 0.274A)~

3.3W(llV X 0.330A), 5.07W(13V X 0.390A), respectively. Moreover, the IT0 thin coating of 6,000 A having, as shown in Fig. 3, a transparency of 80~, it can be adopted as a very important material in production of the conductive glass for automobiles.
Eig. 5(B) shows the cur~e indicating the surface temperatures of the Au thin coating layers of 400 A in thickness, the electric current being 0.114A when it was supplied at 13.8V, the surface temperature showing about 45~C 600 seconds later Fi~. 6~shows the results of XRD analysis of the IT0 experimental piece with -, ~ , - ~ :

~,,i. ~

212~ 4 lo its FO2/FAr value at 0.43. wherein in the case of an experinental piece of good transparency and conductivity its In2SnOs coating exceedingly well develops at 2~ = 45.36. and it was found that the àbove ITO coating contributed to i~proveaent of conductivity.
Such exothenmic reflexible glass. coated over the surface of the glass in automobiles. can be used very preferably to remove the moisture inside. and is extensively ade use of for liquid crystal display systems also.

,

Claims (2)

1. A process of manufacturing an exothermic reflexible glass by the magnetic sputtering technique, characterized in that it is manufactured by cleansing glass with alcohol, distilled water, and aceton in that order, drying it in an oven at about 200°C making it generate plasma in the magnetic filed of magnetron at the electric density of 6-12W/cm3, the initial vacuity of 1 X 10-5 torr, and the working pressure of 6 X 10-3 torr, and coating it with such conductive metals as Cr, Ni, Ag, Al, Cu by sputtering to a thickness of about 1,000 .ANG. or more.
2. A process of manufacturing an exothermic transparent glass by the magnetic sputtering technique characterized in that it is manufactured by cleansing glass with alcohol, distilled water, and aceton in that order, drying it in an oven at about 200°C making an alloy of In(90%)-Sn(10%) generate plasma in the magnetic field of magnetron, sputtering with the flow of Ar gas at 100 SCCM and that of O2 gas at 30 - 98 SCCM. and forming an indium-tin oxide(ITO) thin coating layer over the glass under the initial vacuity of 1 X 10-6 torr and the working pressure of 6 X 10-3 torr.
3. A process of manufacturing an exothermic transparent glass according to Claim 2, characterized in that the flow of Ar gas is 100 SCCM and that of O2 gas is 43 SCCM.
4. An exothermic reflexible glass manufactured by the process according to Clam 1.
5. An exothermic transparent glass manufactured by the process according to

Claim 2.