DE1515305A1 - Method and device for cathode sputtering - Google Patents

Description

IBM DlUtIchUnd InfrnmtUnaU Bün-Nmtthint * C * ttththmft mbH

Böblingen, September 11, 1968 • i-ha

Applicant: Official "files: File number d. Applicant in:

International Business Machine Corporation, Armonk, N.Y. 10 504

Docket 14 125

Method and device for cathode sputtering "

The present invention relates to a method and a device for cathode sputtering, in which thin layers can be applied to any workpieces or substrates by means of the fioebardemonte of a cathode, and a higher precipitation rate is achieved compared to the devices of this type known to date. Although the method of deposition of thin layers has been known for many years, it has been used less often than the deposition of thin layers in high vacuum The most varied of processes for thin layers can be recorded, with non-metallic thin layers also gaining importance, especially in the field of microelectronics and monolithic circuits layers mm fireproof "Haterial asleep" borrowed the oxides, carbides, etc. produce.

.,. New _comments

The mechanism of cathode sputtering uses a glow discharge between an anode and a cathode, in which the current between the named electrodes is maintained by electrons moving towards the anode and by positive ionons moving towards the cathode Oil glow discharge is sustained by the ionization of the gas "which is in the oil of the glow discharge. Here the ionization comes about through impact processes between particles" and an impulse of dead electrons. If the positive ions are accelerated towards the cathode, they lose enough energy with her in collision with the cathode atoms or molecules from the cathode material out · dissolve. In this context, atoms or molecules of the cathode material are "atomized" and these are deposited on a suitable substrate, which in most arrangements represents the anodo itself or is attached to it. It should be noted that the atomized atoms themselves are ionized in the rarest of pills and that the mechanism by which these atoms were atomized is more likely to be explained by the impulse or energy transport processes Olimentladungsgcbletes is controlled.

As we know, the low rate increases «if the current density is increased, i.e. when the speed of the ion bombbaru-dent of the cathode is increased "and the result is" a decrease in the Lower deposit rate at anwaohsondsm Druok, da dlo Ansah! the 3tweet the atomized particles with the surrounding gas proportional to the number the Tellohen present in the plasma grows. In an open closed In the event of a fixed voltage drop, the system can increase the current only achieved by increasing the pressure. On the other hand, will Jodooh with a higher Druok dtr proportion of the atomized atom, welobe The anode is relieved, due to the fact that the impact elements are largely reduced. To the Br * increasing the current density in a "closed system were" in "

909033 / MOS bad original

. > . New registration subloqei

A number of measures were proposed, for example the «Anv /? Ndunc magnetic fields to deflect the Iorwn and the electrons, whereby one is able to hold a larger percentage of the material production in the units of time and thus to achieve a higher ionization. The number of ions that one can produce in this way In addition, you can, but let us use the procedure mentioned limited and the number of ions definitely cannot exceed the number of gauze particles that are present within the closed systems are. Some nebulizers drove ln> the actual discharge * a continuous flow of an ionic alerbaron oasis * "whereby a fixed pressure level is maintained" by letting a defined proportion of gas out of the ooftß. In such Devices, however, are related to the Stron and Druok the area of the discharge and also the rate of atomization the same, as is the case in a closed system and lrgondwelohe Realizable gas increases can only be achieved by causing a corresponding increase in pressure, which in turn irrevocably reduces the lowering rate.

The present invention is therefore based on the task of specifying a method and a device for cathode sputtering in which the atomization rate can be brought to a controllable level in a controllable manner, where it should be possible to increase the atomization rate without changing the pressure in particular the device and / or the process should also be able to knock down thin pilno from refractory materials "t" B, from oxides "carbides U3W" by atomization.

According to the invention, the stated problems are achieved in that Ion sources which are arranged at least once to the dgontllohon discharge track synnctrleoh the discharge track in addition, with one off the generated positive zones and a corresponding number of

909833 / 110S

Existing electrons) plasma as well as the fact that the discharge at ι will lead.

load txil a pressure between 10 · 10 "and 2 · 10 Toirdurohge-

Weitoro details doa Verfahrons according to the invention go nuo the description and the drawings. Xn the drawings mean:

1 is a plan view of a cathodic atomizing device.

device according to the teachings of the present invention;

Fig. 2 is a detailed representation of an inside

the K & thodera spraying device is used

Ion source j Flg. 2a according to a Q.uoraohnlttedars graduation from the ion source

Fig. 2;

Flg. > a representation of the structure of the glow discharge

a cathode arstKubvorriolitung without additional plasma supply and

Flg. > b a representation of the structure of the Ollao discharge

a KathMtnierstMubungevorrlohtunc with SuUtz-High Flaeoasufuhr according to the teachings of the present "

Invention.

When in a gas at a reduced pressure of about 2 x 10 6 Torr up to a few Torr by means of a voltage »greater than that Breakdown voltage dos Gasea is a Dauerenfcl & duug aufreoht- » A discharge structure arises from all anomalous ones Guanine charge is known · With this discharge let thoroh that Gas transported electricity as a function of the applied voltage. U.N* For the conditions mentioned, there are xwel determined discharge probes

S0S833 / 1105

" ^: . · ■. ■ '■ -.." . 1S15305

.important for the maintenance of the discharge. One of these zones is the Crookesschc room or the Kabhoden-Darkroom. This contains mainly positive ions because the electrons because of their greater mobility reach the anode. As a result of this positive zone, the resulting field or chip fall lies mainly in the diose zone and extends to the cathode diode The second important zono lies next to the g ^ ookesechen-dunke room on de? Aenode soap. In this area, the main type of BÜer lonisiorungavorgängö takes place as a result of impacts between two easmolokttien and SoIaindäFelekferonenj, .die .von the cathode staceisa over the dia * ch; © Required field must be requested . .Bieaoi ⁵ sweile Evs * ®ieh Isfe the negative OliraiHzone «Di® Eekimdtoe El®ktroneReiii8Si © ii nmü die roga»

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ilanen- sma time of ÄneetoCcas cino e3ar ^j & t-IiciG It is- on it hlramml »% n _& that öio ^ Ci ^ rjI ^ dar made tea. bsw ο atomized Atoane .-- nleht ionicioi? ^ roz-ä% rii _c i: ochalb

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- 6 - · ■■ 809833/1105

ErIEutorung to the apparatus of the present invention © typa is Bozug .genommen displayed on Fig® I ₄ in Wolcher ein® Zerstäubungvorrichtung ISFC _e This comprises first oin conventional vacuum · kanraspsjpjtem XO ₉ wi @ © e sB * for experiments odor boi dor on damping thin Layers is used »Such a Syatem can also be umkoRsfeFMiert, for the inclusion © ines daa vacuum system durohlauffen & ess feQBtifiMFilieh © ^ Trügörelemsnt & ffij, to a continuously © !! FKE © se ö © 3? ZespsfeSuteungsnie-doreehl & gung durahfUhren au käSnwsn * further ^ to isfc ac & mi hänawwQ & eeiiii that Fig _a 1 ^ iolit iaaistabsgereÄt min SoI so "dal üiQ Abwsmwigßn tew« n !! «» »Koswt i # leah 4®!

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Ji33 / 110§

dor serves as an anodo and two openings 28 cnUiiilt, duroh v / o 1 before one Heating wire 26 alo cathode is clamped · This cathode is over oine »tfeohsölapensionaquolle 22 via the feeds 25 and 24 ge · heats »whereby one side of the energy source · 2} is grounded. Kaiat For this purpose, alternating current from the Hetz of 4 · 6 V is used. The anode 27 is connected to a suitable positive voltage source of about 50 V to IGQ V connected.

Boi Enough hot cathode 26 sends out diose slectrons, which sioh move against the cylindrical walls of the anode 27 When the ionizer Bare gas, e.g. air or its constituents, nitrogen and sausage, get into the electron flow "cause dio between the gas" Molokullen and the electrons occurring collision processes an ionization of the gas, so that in the named area both positive Ionon all electrons are also present; This Plaaea is then integrated into the Qline discharge zone between the sputtering cathode 12 and the Zsr The test anode is introduced. Approximately the same number of electrons emitted by the filament 26 arrive at the zyllndricohon surface of the anode 27 "and there" voe generator 17 sr generated plasma behaves despite the ionization within the olios discharge zone essentially noutralt by changing the voltage or the current of the plasma rator anode 27 and the Fludgesohwindlg * By actuating the valve 18, the gas came through the XonenfIuI be steered into the glow dischargesons

The distances between the line 16 and the gas to be ionized are conveyed to the generators 17 and between the generators 17 and the distance between the discharge zone between the Zsra ^ aabeJrtcathede and the anode 13 are not particularly critical dl «of the lines 16 so mh · wi« Buglieti an dl « t iajsa ^ iBKmter · !! 17 should adjoin, which for their part should adjoin againu «μ nüi ·» io aÜtUeii ffia *!

909833/1105 bath

In a sp®3lsli © a AuefUliruo £ sbeiopiol dor lurfindung the Zor «· afcäubsx'ßBed © geeröefe. and the external cathode is set to a negative potential tob 5000 ¥ gßhr & oä% _B where the distance between the mentioned elec- trodes! «=>. 2 co- fcotagt * The dimensions mentioned above, however, aiehfe IcrlfeiSQli iwd Wrsma itsodifisiert

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h @ Fauezuste2en · As in Fig. 3 * geselgt * the Zons tii @ d® and the anode are divided into five zones as the Btsel A, B ₀ '■' - 3 νωά E · The zones concerned are slightly duroh

Functionally hollowed-out bar marked “un difference” in the strings · der MdiUnteneität, divide each zone from it · Here · - -stronger® dots correspond to darker zones and sohKtfJther dots to lighter zones · O & s area B represents the Crookesschen darkness, which was briefly explained above and which was briefly explained above Ia the HsxiptSAohe §u » positive

90S833 / 1105

Ionon boots, with the same density prevailing across the area. The raised tail of the voltage drop and the electrical field lies between the anode string of this zone and the cathode. The largest part of the ionization processes takes place in the negative glow zone, which is represented in Fig. 1 by zone C, which glows in the light tone of all zones of the glow discharge and which is characterized by a slight excess of negative charge as a result the fact that diodes were accelerated from the cathode by the voltage drop within zones A and B. Zone A is generally referred to in the literature as the cathode glirara light and contains an excess of negative charge as a result of the secondary electron emission that occurs the ion bombardment of the cathode surface is caused «Zone D has a lower intensity than the negat ive Qliramlicht and is easelohnat in the literature as the F & radaysoha Dunkelraua, while Zone E is called the positive column. Faraday's dark brown and the positive column are essentially neutral, although they also contain ionized particles. Every ion movement in zone D and zone E occurs mainly through diffusion, since in these zones there is little or no fall. The boundaries between zones C and D and also zones D and t. are indicated by broken lines, because at the reduced pressure applied to the apparatus of the present invention, the presence of these zones is difficult to recognize like in Pig. Jk shown, la comparison With illustrations in standard textbooks, which describe the general Gllsawentladan at higher pressure, confused

Although other zones are also present in one discharge can, which have their own characteristics, were ioleha Zonan ' in fig. 3a and 3b not shown because their «meaning in Basug on dia before · present invention is small

• 10 -909833/1105

The zones described above inherit 3ieh In the eye of the ignition of the discharge line, where dip Olimmontlartun /; o I build up. At the same time, the electrons are accelerated and run through the cathode dark space to the cathode, the largest toilet in the field building up over the dark room to the cathode. The zone in which the ionization mainly takes place is the place where the slectromes leave the cathode dark room. The corresponding dimensions <| er different zones cteilen to build -the "ntladung co one that a FTIR the lonisatlonsprozees optional PotentialYertollung results in this process depends on the applied voltage umdem Druok from Will \ an increased number of positive and negative ions.. When introduced into the system, as in the case of the present invention, this results in a change in the potential advantage. A change in the Faroinoter, for example the pressure, also eliminates a change in the potential distribution.

The strength of the Crookessohen Dunkelraueee is inversely proportional sum pressure; some writers write this on the fact that the mean free paths of the electrons, which the Crookessohen Dunkel space through quoron, perform a fixed number of thrusts before they au9 from the dark room into the negative Glirmucon *, where they are used for further initiation processes play a role.

Just like an increase in pressure, an increase in current density As a result of the increased ionization of the negative oliaazono naoh themselves sees, an orhuhte ionization also has an increased current density, Your consequence, and this gives the appearance of increasing pressure, although this is kept constant. This is shown in Pig «3b, the one representation of the olympic charge structure for apparatus «1st» using the present invention.

BATH

909813 / ITOS

1516305

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Recyclable gas «wi * carbon, nitrogen-chlorine Βγοο can be used in parts of oxygen »tm aue carbides »Kitridon, Chloriden und Broaidtn su erztustn · Aüseordeai instead of argon, other non-reactive oases such as Hellt », Neon and Xenon are used.

90 9 853/1105

"Is the cathode" for operating the Flasmacenerator, which is made of a tungsten wire, by means of ßohoizt oinns Weohsclotromoo 50 H ^ rtz and about 4.5 V, the anode 27 to a voltage .If "· source of otita 8o connected and V an anode current of about

Raised for cathode and ordinary OAAO is the abnormal Kathodon waste by dl "Beziohung _Λ

_m π +

described, wherein £ and F are constants, J dl · current density ρ and the gas pressure means ·

The equation shows that for a given voltage in a closed system without an additional ion source, the pressure can only be increased by increasing the pressure. If, however, according to the teachings of the present invention, an additional ion source is used, then the change in the Stroudlohte results in a change in one or both constants.

PUr the atomization rate M became «epirlsch following Fore»! found!

where 1 is the current, ρ is the pressure and C. and C _{2 are} constants. It can be seen that for a constant pressure the pressure is increased when the dryness is increased, while an increased pressure has a detrimental effect on the decomposition.

While the pressure in the atomizing apparatus should be higher than 2 · 10 " ² Torr to ensure the division of a sufficiently high current density, it was found that the atomizing rate decreases when the pressure increases to more than 10 · 10" ² Torr "da dl ·" · rs deaf molecule "often" suffer "collisions on their way to the anode

^ 0 ^ 833/1101

wahrend'die present invention is particularly favorable tor the sputtering of hitzefeaton materials and varseniedenan Qauarten Uuruh Ze rs täuben wit equilateral oheoiXsohor Umaetzun £ ₉ is a Ixiatandteil wobui of the ionized gas is vorwendat to react with the asu goratäubton of dor cathode Matorial and above büeohri "- boüi oine l & edersohlagueohioht, ao the invention is also easily applicable to other devices that need a zone boobar moment of a cathode G" like the "χ · Β · at" some of a substrate on the surface «InArKathod · and in other luinliohen applications the case lat ·

"■ - ■■. '. - .i

BATH

909833 / 110S *

Claims (4)

Patentana ρ r ü ehe A method for applying thin silicate by cathode sputtering, characterized by the fact that at least between the ion sources arranged for the discharge of charge scattering, the charge path is supplemented by a plasma consisting of the generated positive ion and oinar corresponding to the number of electrons that supply the plasma Discharge at a pressure between 10 · 10 and 2 · 10 Torr is durohco performed. 2. Procedure naoh Anepruoh 1, daduroh marked that the Discharge path to be supplied plasma from a chemical positive Ions and electrons consists, the ions being more sufficient by bombarding an ionizable oasis with electrons kinotic energy are generated and the electrons dom hieriu used Klektronon stream 3 «Method according to claims 1 and 2, characterized by since / 5 the gas discharge serving for atomization is carried out in an inert gas, dom small amounts of with the cathodonrcatorially reacting oases are fed 4. The method according to claim 3, characterized in that for He zcugunc thin layers of carbides, nitrides, oxides, chlorides and chloride in the indifferent gas, insignificant quantities of an oxide of the Kohlonstoffee. Oxygen, nitrogen, chlorine or bromine »is converted. . BAD ORSQiWAL 909833/1105