DE1542589A1 - Method and device for removing contaminants from the surface of a layer support or the like. - Google Patents

Description

Libbey-Owens-Ford Glass Company

811 Madison Avenue, Toledo, Ohio, USA

"Method and device for removing contaminants from the surface of a substrate or the like. "

For this registration, the priority is the corresponding U.S. application Ser. Ho. 484 417 dated September 1, 1965.

The invention relates to the removal of contaminants from the surface of a substrate or the like and relates in particular to an improved method and a device for cleaning der.Oberfläche a support or the like. by means of vacuum glow discharge.

As is well known, one of the air forms on the surface exposed object sometimes a contaminating coating or coating. This contaminating surface or coating usually occurs in the form of adsorbed or absorbed gases or in the form of an oxide coating on the surface of the Object. Oxide deposits can be visible, such as the characteristic that forms on a copper surface

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For the "contract whatsoever" applies the "GabOhnnordnung der Deulidien Pot" ntanwältileamm ". - Funding for performance and payment: Btriin-Chailattmbntg Conversation at the FwnsprcdiM raised no iKhtivwbindlith Wiikung, BATH ORIGINAL

see greenish coating (patina), 'or be invisible, such as the oxide that forms on aluminum covering. The presence of an oxide film or other various types of contamination on a metal or other surface is sometimes undesirable. If, for example, with the aid of vacuum evaporation processes or techniques on the surface of a substrate or the like. A thin film of suitable vapor deposition material is to be applied, the presence of impurities may occur on the surface of the Schiddit support the between affect the bond formed on the vapor deposition material and the surface of the layer support. Of the The term "impurities" as used herein includes any and all material deposited on the surface of a substrate or the like, or all of them into the substrate adsorbed or absorbed gases that are released between the substrate and the with the help of vacuum deposition process or techniques applied to the coating on the substrate.

Attempts have already been made to use the surfaces of a layer support or the like before it is coated Purify with the help of various chemical agents. However, such means have generally proven to be inadequate proven, since a sufficiently high degree of purification can often not be achieved with them, whereby the

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chemicals used for the substrate are sometimes harmful. Also means were developed to chemically clean the surface of the substrate to be cleaned. neutral particles, for example with argon, neon atoms, etc., bombard EU in order to detach or remove impurities. The cleaning by bombardment has generally been inadequate because the detached contaminants remain in the system and are sometimes redeposited on the surface of the substrate or object to be cleaned, with other contaminants present somewhere in the system being sometimes detached by the bombardment and on the way cleaning or »cleaned surface can be deposited.

It is also known that the surface of metals, glass and other items with the help of a general as Glow-discharge cleaning known Process can be cleaned. Glow discharge cleaning is done by standing in the area of the object to be cleaned builds up an electrostatic field with a high voltage gradient in a vacuum chamber. Then the vacuum kaamer a sufficient amount of an inert gas is admitted so that the electrostatic field does the ionization of the oasis and the onset of a "self-entertaining Brings about limb discharge. The gas ions are Electrostatic field accelerates and to the surface of the

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Layer carrier attracted, on which they hit at high speed, so that existing on her Impurities are relieved or removed. the mitteis glow discharge cleaning from the surface of a Sealing carrier or another corresponding object loosened contaminants also remain in the system and sometimes reappear on the surface of the layer carrier deposited so that they ..this Making procedures quite ineffective.

The object on which the invention is based is to create an improved method and an apparatus for cleaning the surface of a substrate or the like.

Another object of the invention is to provide an improved method and apparatus for cleaning the surface of a substrate or the like. by means of glow discharge in order to achieve a relatively contamination-free Surface.

The invention is explained in more detail below with reference to the accompanying drawing. It showj

Pig. 1 A schematic side view of an embodiment a device according to the invention, in

Partial cut and

Pig. 2 shows an enlarged representation of the section along line 2-2 in Pig. 1.

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According to the invention, a method for eliminating Impurities from the surface of a support or the like. Suggested in which the support introduced into a vacuum chamber and an electrostatic high-voltage field is generated in the vacuum chamber is, characterized in that a reactive gas is introduced into the electrostatic suffering and the field is adjusted to an intensity to reduce the ionization of the reactive gas and the formation of negative ions bring about that with at least part of the on or contaminants in the substrate surface to be cleaned enter into a chemical compound can so that the ions accelerated by the electrostatic field impinge on the substrate surface and cause the impurities to be removed from it by bombardment and by chemical reaction.

According to the invention there is also a device for eliminating the impurities from the surface of a substrate or the like. put in proposal that one evacuated Chamber and means has an electrostatic in the evacuated chamber in the vicinity of the surface to be cleaned Build up field, characterized by means for introducing a reactive gas into the electrostatic field and by means to? to control the electrostatic field so that the formation of negative ions is brought about will be dealing with at least part of the on or impurities in the surface

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chemical compound can enter into, so that the reactive Ions are accelerated against the surface and clean them by bombardment and by chemical reaction.

The device shown in the drawing consists of a high vacuum chamber 10, which contains means 12 to in the Chamber 10 to produce an electrostatic high voltage field. Further, means 14 are appropriate amounts of a reactive Introducing gas in the electrostatic field, and (not shown) means provided to a in the chamber 10 to be cleaned layer support 15 to be passed through the electrostatic field.

The high vacuum chamber 10 is connected to a vacuum pump 1b, which is able to move the chamber on a relatively to keep low pressure, which is suitable for maintaining glow discharge processes. The chosen special Pressure is generally dependent on the associated equipment, such as the shape of the electrode, the Type of gas introduced and the characteristics of the electricity supply, depending. In general, the pressure in the

High vacuum camna? between about 5.10 torr and 100.10 torr; 5-100 held, although other pressure values are sometimes also used; can be suitable, TJm the entry of undesired gases in! "

to prevent the chamber and in it the necessary yakuufo ^f o I

^ two vacuum-tight locks 17, 18 _f

OO ■ ■

ίο provided for the passage of the Schiohtträgere 15 through the "^ Chamber 1Oy If a material is treated with a different Forii els *" that of an elongated strip of material, the vacuum chamber 10 can be easily modified * m chea material to process. At spi eiaweiöf, can

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A door has been provided in the chamber, through which material formed by oil can be turned around and the workpieces can be removed.

la is sweet, a facility 21 vorstasefcen - um .that. electrostatic field as well as the reactive that on cover the surface of the visual support to be cleaned limit the preselected area of the chamber 10 au. Dut eats required with Sücksiclit on the pro-rata high chemical reactivity of the calibration during ionization dee reactive gas "forming negative lots that With the walls of the chamber 10 or with others in it enter into a chemical reaction with existing materials kttnns * eof em .no pre-charge is made to the electrostatic 7eld and the negative ions on a demarcated Area Ib to restrict the interior of the chamber 10. One Pors the device 21 to limit the electrostatic charge As can be seen from Fig. 1, the field consists of middle Xn, one including a suitable part of the substrate 15 la interior of the chamber 10 centrally arranged chamber 22 delimit, eo that the electrostatic field and the negati-V Vem ions on the area bounded by the chamber 22 be restricted. Me the chamber delimiting means can made of a stable, non-conductive material ItAd is made up of two opposing, mutually

ι * t '-1Jtritoftten rectangular boxes 23 and 24 with an open top - ¹ || assist. Each of the boxes 23 and 24 has a bottom wall

r J ^ jl | * ilit u «them around vertically arranged side walls 2b * • t7. The to the bottom wall 25 of each of the boxes 23 and 24

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perpendicularly arranged walls 26 and 27 terminate in one another separated position in such a way that the substrate 15 can pass freely through the chamber 22 while they simultaneously confine the electrostatic particle and reactive ions to the interior of the chamber 22.

The means 12 generating the electrostatic field are arranged in the interior of the chamber 22. In the illustrated embodiment in the drawing, these means consist of a first and a second electrode 34 or 35 "a-i ^m ie interior of the chamber 22 are disposed on both sides of the substrate 1b. The electrodes 34 and 35 act similarly to a cathode. The electrodes 34 and 35 are preferably arranged relatively close to the bottom wall 25 of the boxes 23 and 24. The electrodes 34 and 35 are connected via a line 38 to a high-voltage source 40 which keeps the electrodes 34 and 35 at a relatively high negative potential with respect to earth. In general, a suitable operating potential between about 350 and about 5000 y is chosen. The substrate 15 is kept at ground potential and acts similarly to an anode in that it is opposite to the electrodes. 3 «and 35 have a relatively high positive potential j-afv / eisx. As a result, the 3 ^ώ una arises between the electrons. 2>:; and the surface of the substrate 15 is a high voltage electrostatic field. The electrodes 34 and 35 extend like Pig. 1 seen in the longitudinal direction 15 of the chamber 22 and the Sdichtträgers The Elektroaen marine s "ca also sur chamber 22 extending in the transverse direction,

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namely, such an embodiment is required in a layer support of considerable width in order to be uniform over the entire surface of the layer support build up an electrostatic field. Instead of the individual electrodes shown in the drawing, several electrodes can also be used Electrodes, if necessary on each side of the sheet carrier or the like to be treated., Are used.

The reactive gases are in the electrostatic field introduced so that an ionization of the gas and the formation of reactive negative ions are brought about. In a preferred illustrated in the drawing Embodiment of the invention is the reactive Ga, through electrodes 34 and 35 into the electrostatic Field fed into it. For this purpose, the electrodes 34 and 35 preferably hollow so that they have chambers 4? delimit or 48, and are provided with 'numerous openings or breakthroughs' 44, 45 in their walls facing the layer support 15. The gas supply device 14 consists of a line 50 which is connected to a suitable gas source via a control valve 54

"I Ie 52 is connected. The line 50 runs into the chamber 10 and is connected to one end of each of the hollow electrodes 34 and 35 via distributor lines 55» 56, which connect the electrodes 34 with the aid of a non-conductive ring-shaped spacer 57 »58 and 35. The gas is fed from the gas supply line 52 via the line 50 and the distributor lines 55, 56 into the electrodes 34 and 35 and passes through the

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Openings 44, 45 from the chambers 47 »48 into the inae ## of the chamber 22. The gas prevailing in the chambers 47» 48. \ Pressure Ausafcrömen the leads of the reactive gas aas the openings 44 '45 in Bichtung on the substrate ~ 5% and its impingement on it by natural convection induced. This is useful and advantageous insofar as it is used to limit the negative ions to the chamber 22 and the. leads to the surfaces of the layer carrier 15 adjacent area.

The reactive gas can be any gas that is ionized in the electrostatic PeId built up inside the chamber 22 and negative when it is ionized Forms ions that are associated with at least some of the impurities present on the surface of the substrate are reactive, -It is advisable that the negative Ions with the impurities have a fieäction in the way enter that gaseous reaction products are formed, which are removed from the system with the aid of the vacuum pump can.

Mainly by chemical reaction with the ^negative: ion impurity to be removed iet a Oxyiibeläg or '■ overcoat, such as might be present on a metal or glass Scüieht "* carrier. Accordingly, the reactive gas is preferably ei "säiofte * dft" neg ^ -tlf "forms ionity" which binds with oxides in such a way that they form gaseous reaction products. Btvorsttgte r · ** tion · <gases are those | a. _Ä the EeduJttieiieai-tti ^ einfi f

oosizf / fill: < i

many fibrous and gaa-shaped halides (halides), btifcfiei irichlorätzylen (C ₂ HCl ₅ ), HGl, GH ₄ , C ₂ H ₅ ad iretaehiedim-like fluorocarbons. Irichlorethylene is used for removal. Oxide coating or over- £ Ugee * »a of the surface γοη steel is particularly suitable, .. '

In operation, a suitable voltage trough is applied to electrodes 34 and 35, for example a potential that is about 1500% negative with respect to earth. If the layer substrate 15 is made of a conductive substance, it will be trodden, so -a.8 between the electrodes 34, 33 and surfaces of the layer substrate 15 an electrostatic "tetelite" should the cleaning layer substrate fall into a Siclitak "| ii" r, as bftiajprieleweice glass is, causes the creation of the "egative boteatlals on the electrodes 34, 3b -" Q build-up of a positive static charge on the other

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the lying surfaces of the layer carrier material 1b, so ΑίΛ «wisciiea the electrodes 34, 35 and the layer support a" feeri * l 15 a high potential difference arises. As a result builds aich between the Elektroaen 34, 35 and-den Flacher. of the substrate 15 an electrostatic field with between ct «m electrodes 34, 35 and the respective surface of the substrate 1b running electrostatic line of force.

The reactive gas is then passed through the hollow electrodes through into the electrostatic field between the electrodes "

and introduced into the substrate. The introduction of the Reactive gas continues until sufficient gas pressure is established in chamber 22 to generate a bring about sustained glow discharge. The glow shows the initiation of the ionization of the gaeatome by the in of the chamber 22 produced electrostatic field. The free Electrons can collide with neutral. Atoms of the reactive gas also generate additional ions, each of these collisions creating an extra free electron and an extra "ion, so that there is a continuous generation of additional ions. In general, the glow is at a suitable one at the illustrated embodiment essentially

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pressure between 5 * 10 ' and 50 * 10 Torr produces a self-sustaining glow.

The size factors of pressure and tension can be the same can be adjusted to achieve a self-sustaining glow resulting from ionization from Gasatomer. by sicn in the substrate 15 results in moving electrons. It is beneficial to reach the point at which the glow entertains itself without going too far beyond this puruct, the determination of this Point is relatively critical because it is often proportional near the glow point at which the glow is self-evident becomes entertaining, the arc discharge begins to occur,

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which for the present purposes is generally one undesirable effect is as it leads to an additional Pollution or contamination of the under treatment can lead to the substrate. Arcing often causes irreparable contamination or damage to the material being treated in lieu of its settlement, insofar as than punched holes in the material by arcing can be. The current source is preferably a customary, precisely controllable current source, since this is prevented when it is prevented arcing after reaching the glow range is advantageous. This is due to the stability such a device that eliminates voltage surges that could lead to arcing.

When achieved a self sustaining glow discharge is and negative ions are generated, the ions, provided that the layer carrier material 15 is conductive, endeavor to from the electrodes 34 and 35 to the earthed Layer carrier material 15 to move. Unless the material is not conductive, see the negative ions move accordingly from the electrodes 34 and 35 to the positive ones charged surfaces of the material 15, in both cases the ions get from the electrodes 34 and 35 to each other opposite surfaces of the material 15 so that they impinge on these surfaces, such a bombardment not only endeavors to remove impurities present on the surfaces of the material 15 with the help of the impact of the impact

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to be removed, but are the ones that hit the surface,

Highly reactive negative ions also strive to have a chemical with the surface impurities To receive a response. In general, these reactions produce gases such as carbon monoxide, which do not easily adhere to the surfaces of the layer carrier material 15 and can thus be easily removed. In particular Cases can not be gaseous reaction products, such as solid-state fluorocarbons or organic metal compounds, which calibrate easily removed by simply letting them fall from the material by gravity. Thus the The surface of the substrate to be degassed or cleaned is soiled by the impact of charged particles against it its surface as well as through the chemical connection of the reactive, negative ions with the impurities treated on its surface.

In the preferred embodiment of the invention constructed with Success, a steel strip was inserted into an evacuated vacuum chamber. ¥ ia the steel strip around a facility or chamber is arranged to limit the elektcstatißchen field of about 60 cm length from aluminum so that, between the running in the longitudinal direction _f walls of Kammner and the Stelilstreifen a distance of about 51 mm was present in the chamber were relatively close to the jj * temporary upper b. * w · lower W * & d awel "* ^:

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Electrodes «! The reactive chloro-ethylene gas (CpHOl ₅ ) was introduced and, at a pressure of 50-10 "lorr, when the electrodes were fed with 1500 V at 5 A, an optimal glow discharge took place. Under these conditions an effective cleaning was achieved The surface of the material is achieved by leading the steel strip through the chamber at a speed τοη approx. 3 m / min.

In the case of strip or wire-shaped material being processed below is the combs: 10, as discussed above, for processing of the Xfttexiais suitable. It also can be for others KattrifcXformen light «provided in a suitable chamber structure will. For example, when cleaning hemispherical material is to be provided, the canoe in a chamber • s enables the reactive gas to be fed into the concave rope trimmed by the wall of the 4-part hemisphere. In aer A suitable electrode can be seen at the opening of the material be arranged so that then the opening from the rest of the Chamber «for example with the help of a simple cover, sum feit, can be locked lean, which serves» the glowing process to be restricted to the interior of the hemisphere.

Gewüaeofctenfalls the purified material from the

Lö immediately the input of another device if subsequent operations,

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for example a coating by means of vapor deposition, a machining, etc., are to be performed. On the other hand, an additional treatment or processing, of the cleaned material carried out in the vacuum chamber 10 will.

The invention thus leads to an improved method and an improved device for disposal of impurities and soiling from the surface of a material. '.'

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Claims (1)

Claims 1 · A method for removing contaminants from the surface of a substrate or the like, in which the substrate is introduced into a vacuum chamber and an electrostatic high-voltage field is generated in the vacuum chamber, characterized in that a gas capable of action is introduced into the electrostatic pathway the level is set to an intensity to bring about the ionization of the reactive gas and the formation of negative ions, which can form a chemical bond with at least some of the impurities on or in the substrate surface to be cleaned, so that the electro - ^: Static field accelerated ions strike the substrate surface and remove the impurities from it by bombardment and by chemical reaction. 2. The method according to claim!, Characterized in that the electrostatic pressure on a limited area (22) the vacuum chamber (10) is restricted. ... / 18 0O982S / 1S83 GOPY 5. The method according to claim 2, characterized in that the negative ions with at least part of the or present in the substrate surface (15) Impurities form a compound in such a way that gaseous reaction products arise from the the area surrounding the substrate (15) can be removed. 4, method according to one of claims 1 to 3, characterized in that that the reactive gas is a gas consisting of gaseous organic reducing agents, 5. The method according to any one of claims 1 to 4, characterized in that that the reactive gas is made up of hydrogen, methane, ethane, trichlorethylene, hydrogen chloride and gaseous fluorinated hydrocarbons is the selected gas, b, the method according to any one of claims 1 to 5, characterized in that that the surface of the lens carrier (15) steadily through the vacuum chamber during the cleaning process (10) is moved through. 7. A device for performing the method according to claim 1 to 6 consisting of a evakuierteren chamber and egg _f ner apparatus for forming an electrostatic field within the evacuated vacuum chamber in the vicinity of the eu-cleaning Oberflächt, characterized by in that ÖQ962S / 1M3- \ ../ \ 9 electrostatically I «ld a reactive gas introducing line (H) and through devices (16, 40), lur control of the electostatic field such that ti * ionization of the reactive gas and the formation of iron negative ions takes place with at least a! bearing of the calibrated in the surface (15) Impurities can form a chemical compound, so the reactive ions against the surface (15) be soled, and by bombarding them as well as by clean cheap reaction. . Ö. Umrishtung according to claim 7, "characterized by a electrostatic field on one to be cleaned _{ . ^ - ifllohe (15) adjacent area (22) restricting gate direction. f. Irrigation according to claim 8, characterized in that Aie compression $ 1) BKi restriction of the electrostatic | fHf · from two * n their top open, in the Kaaaer (10) ^ imaader boxes arranged opposite one another (23.24) Casmer open to the inside at the front (22) form part of a lower wall (25, 25), (22) toi at least part of the too ■ ■ ■. ' * ■ ■ (15) herusi i · essential central BATH ORIGINAL 10. Establishment of naeli claim 9> characterized in that between at least one of the walls (25) of the chamber (22) and the surface of the substrate (15) at least one high-voltage electrode fed by a source (34,35) is arranged, which builds up an electrostatic field in the chamber (22), and that a vacuum pump (16) and a gas source (40) are provided for controlling the intensity of the electrostatic field and the Pressure of the reactive gas in the chamber such that the ionization of the gas and the formation of a Glow discharge can be achieved in the chamber near the surface to be cleaned. 11. The device according to claim 9, i * characterized by a substantially hollow in the longitudinal direction through the chamber (22) between the upper wall (25) and the top of the layer carrier (15) extending first high-voltage electrode (3.4), which in their dem The wall facing the layer support (15) has numerous openings or perforations (44) through a substantially hollow high-voltage electrode (35) extending in the longitudinal direction through the chamber (22) between the lower wall (25) and the underside of the layer support (15) » the Vtand facing the sheet carrier (15) zxahl- ^! has rich openings or breakthroughs (45) through one with the first (34) and the second electrode (35) connected power source (40) around electrodes opposite Brd to keep it at a high negative potential «and durob. ■ - j Means to the surfaces of the safety device (15) in the stsu * OWGlNAL INSPECTED to keep the first and second electrodes (34,35) at a high positive potential, so that the high-voltage electrostatic field in the chamber (22) between the first and second electrodes (34, 35) and the respective opposing surfaces of the substrate (15) arises. 12 »Device according to claim 11, characterized in that the responsive. Gas into the interior of the hollow electrodes (34,35) and supplied by those present in them. Openings or breakthroughs (44,45) in the electrostatic Field is directed into and against the surfaces of the substrate (15). 13. Device according to one of claims 7 to 12, characterized by a steady leading to the substrate (15) to be cleaned through the evacuated vacuum chamber (10), known conveyor device. Patent attorneys Seiler ü. Penny BATH 009825/1 £ 83 ti Blank page