JP2019062228A - Method and device for substrate surface treatment - Google Patents

Abstract

To provide a method and a device for removing a chemical impurity on a surface of a semiconductor or a harmful substrate surface layer (for example, an oxide including a native oxide, a carbon, and a carbon compound) without causing an additional fault due to minimum damage to a substrate surface.SOLUTION: A method performs surface treatment including the steps of: arranging a substrate surface 7o in a process chamber 8; applying an ion beam 3 containing a first component to the substrate surface 7o to peel an impurity from the surface substrate; and introducing a second component into the process chamber 8 to link the peeled impurity. An ion sputtering device 1 comprises a process chamber 8 for housing a substrate 7, an ion beam source 2 for generating an ion beam 3 containing a first component directed toward the substrate surface 7o to peel the impurity from the substrate surface 7o, and means for introducing the second component into the process chamber 8 to link the peeled impurity.SELECTED DRAWING: Figure 1

Description

  The invention relates to the method according to claim 1 and the corresponding device according to claim 9.

  In the semiconductor industry, various wet chemical etching methods and / or dry etching methods are used for surface treatment, in particular for surface cleaning and surface activation. These etching methods are used in particular for the removal of natural surface oxides and / or carbon compounds. A significant difference between wet chemical etching and dry etching is the physical state of the detergent species used. To clean the substrate surface, a liquid is used in the case of wet chemical etching, but a gas or plasma is used in the case of dry etching. Wet chemical etching is still the reason for some applications, but has been replaced by dry etching equipment in many other applications in the last few years.

  A plasma device or an ion sputtering device is mainly used for dry etching.

  A plasma device is understood to be a device capable of producing quasi-neutral gases, so-called plasmas. By applying a voltage between the two electrodes, the process gas is ionized to form an ionized quasi-neutral gas, so-called plasma. This device is referred to as "capacitively coupled plasma (CCP)"-plasma device. So-called "inductively coupled plasma (ICP)"-generation of plasma by magnetic devices in plasma devices is also conceivable. In this case, electromagnetic induction is used to generate the plasma. Furthermore, other methods exist to generate the plasma, but these methods will not be described in detail here. The further description generally applies to all plasma devices, but the description is made using a CCP-plasma device, as this structure is relatively simple.

  This plasma is caused to act on the surface of the substrate which is preferably present in the vicinity of one of the two electrodes or in the vicinity of one of the two electrodes according to its characterized properties. In general, inert or reactive process gases can be used. In the case of a plasma device, the voltage between the two electrodes, the gas composition and the gas pressure are preset. In this case, the low temperature plasma ignites above the critical pressure. This critical pressure is greater than the pressure in the high vacuum chamber but less than 1 bar. Low temperature plasmas usually consist of oxygen, nitrogen, noble gases or relatively complex gaseous organic compounds. The low temperature plasma physically and chemically modifies the substrate surface by ion bombardment and radicals generated in the plasma (Source: S. Vallon, A. Hofrichter et. Al, Journal of Adhesion Science and Technology, (1996) 10, no. 12, 1287). Physical modification can in particular be attributed to the high velocity and the associated collision energy of gas atoms and plasma atoms with atoms of the substrate surface.

  On the other hand, the ion sputtering apparatus has an ion source and an acceleration unit. The process gas is ionized in the ion source and accelerated toward the substrate surface through the acceleration unit. The accelerated ions form a so-called ion beam with an average diameter, corresponding divergence or convergence and energy density. The accelerated ions can release the impurity from the substrate surface if the kinetic energy is greater than or at least as great as the binding energy between the impurity and the substrate surface. During this process, the kinetic energy of the ions can of course also affect the substrate surface itself. This influence appears in the change of the microstructure of the substrate surface, the formation of point defects, the ions incorporated in the crystal lattice, the plastic deformation and the like.

  The removal of impurities is also referred to as sputtering. For completeness, it is pointed out that the deposition process of atoms on the surface can also be called sputtering. In the further process, sputtering is, of course, always taken as only the removal of atoms.

  The technical problem is that reactions can occur between the impurities and the ions to be removed on the substrate under given ambient conditions, in which case the impurities are not removed from the substrate surface. Furthermore, the ions also react with the basic material to be cleaned, which is usually present below the impurities to be removed. This results in uneven removal and thus increased surface roughness.

  Furthermore, gas atoms and / or plasma atoms are frequently adsorbed on the surface of the substrate.

In particular, the removal of the impurities with hydrogen is carried out mainly according to the prior art, using the following method:
Plasma method The substrate surface is irradiated with hydrogen plasma. In this case, the temperature of the surface is usually raised very significantly by the plasma. In general, different plasma processes are also used for different materials. For InP, for example, the so-called ECR (English: electron cyclotron resonance) plasma is used (source: AJ Nelson, S. Frigo, D. Mancini and R. Rosenberg, J. Appl. Phys. 70, 5619 (1991) )). Removal of all surface impurities of GaAs was observed after about 30 minutes by hydrogen irradiation using RF (radio frequency) plasma at a temperature of 380 ° C. (Source: SW Robey and Sinniah, J. Appl. Phys. 88, 2994 (2000)). For CuInSe ₂ removal of surface oxides has been described, for example by using hydrogen-ECR-plasma at a sample temperature of 200 ° C. (Source: AJ Nelson, SP Frigo and R. Rosenberg, J. Appl. Phys. 73, 8561 (1993)).

  2. The substrate surface is heated above 500 ° C. in vacuum under the action of molecular hydrogen. In the case of GaAs, this requires, for example, a cleaning time of up to 2 hours (source: DE 1 0048 374).

  3. The substrate surface is heated in vacuum with the application of atomic hydrogen. In the case of GaAs, this takes place, for example, preferably in a temperature range of 350.degree. C. to 400.degree. This method is described in the literature (source: by Y. Ide and M. Yamada, J. Vac. Sei. Technol. A 12, 1858 (1994) or by T. Akatsu, A. Ploessl, H. Stenzel and U. Goesele. J. Appl. Phys. 86, 7146 (1999) and DE-A 1 0048 374).

Ion Beam Method The removal of surface impurities using inert gas (Ar, N ₂ , xenon, ...) in the ion beam method is mainly based on pure sputtering removal (Source: JGC Labanda, S. A. Barnett and L. Huitman, "Sputter cleaning and smoothing of GaAs (001) using glancing angle ion bombardment", Appl. Phys. Lett. 66, 31 14 (1995)). The use of reactive gases (H ₂ , O ₂ , N ₂ , CF ₅ ) is mainly based on the chemical reaction of the process gas with surface impurities and the subsequent removal of this reaction product (desorption, partial Promoted by thermal or ion bombardment). In this case, hydrogen was found to be the preferred process gas for the removal of various surface oxides and hydrocarbon impurities on the surface of the semiconductor (source: DE-A 102 10 253).

  The methods cited in the prior art of surface cleaning are generally utilized for pretreatment of the substrate surface for subsequent processing. Subsequent processes are, for example, coating with photoresist, vapor deposition processes such as deposition of one or more atoms or molecules by physical vapor deposition (PVD) or chemical vapor deposition (CVD).

  These ions create surface defects, in particular in the semiconductor material, which can critically impair the electrical function of the component. Furthermore, in the case of the prior art, the basic problem arises that the plasma device and the sputtering device essentially always modify the substrate surface and thus usually fail.

  When using a plasma process or ion sputtering process for cleaning or activating, for example, Si, SiC, quartz or 3A-5B semiconductor surfaces, the essential disadvantage is the additional damage to the surface of the semiconductor (e.g. Roughening, formation of metal phase, growth of oxide layer, formation of thin water film). The plasma system provides effective surface cleaning that can be detected in the case of most impurities, but particularly in the case of organic components, this cleaning method is sufficient to completely remove the organic compound. Clearly not.

  The main causes for the generation of damage by plasma devices are mainly the direct contact of the plasma with the semiconductor surface and the plasma components resulting therefrom (eg ions, radicals and highly excited molecules / atoms, electrons and UV) Interaction between photons) and atoms on the substrate surface. In particular, highly excited, thereby energetic particles or ions of the plasma, or particles or ions of the ion sputtering device, with high probability the disadvantageous damage process of the substrate surface, in particular the highly sensitive semiconductor surface. cause.

  The low-temperature plasma produced by oxygen, nitrogen, noble gases or relatively complex gaseous organic compounds modifies the substrate surface both by ion bombardment as well as by surface reactions by radicals present in the plasma (source : K. Harth, Hibst, H., Surface and Coatings technology (1993) vol. 59, no. 1-3, 350). Furthermore, gas atoms are absorbed on the surface (Source: K. Scheerschmidt, D. Conrad, A. Belov, H. Stenzel, "UHV-Silicon Bonding at Room temperature: Molecular Dynamics and Experiment", Proc. 4. Int. Symp. On Semiconductor Wafer Bonding, September 1997, Paris, France, p. 381).

  The critical disadvantage of cleaning semiconductor surfaces under the action of atomic or molecular hydrogen in a vacuum atmosphere is that usually a high temperature of at least 400 ° C. to 500 ° C. is required (see: Germany Patent Application Publication No. 10048374). This high process temperature is necessary to enable effective reaction of hydrogen with impurities and to allow desorption of the resulting particles of reaction product.

  Another disadvantage of the methods described in the prior art for cleaning semiconductor surfaces using molecular and / or atomic hydrogen is the long process time, which is at least 2 hours in the case of molecular hydrogen (Reference: DE-A 100 48 374).

The use of the embodiment of the invention from DE 102 10 253 B1 of the patent document is not sufficiently effective, since Si, SiO ₂ , SiC by purely chemical processes using hydrogen ions The removal of impurities from quartz, and Zerodur does not cause complete removal.

  Thus, the object of the present invention is that minimal damage to the substrate surface results in additional disturbances at the substrate surface or in the bulk, such as, for example, an increase in surface roughness, a change in stoichiometry and a failure in the crystal lattice. To provide a novel method which enables the removal of chemical impurities or harmful substrate surface layers (eg, oxides including native oxides, carbon and carbon compounds) on the surface of a substrate, in particular a semiconductor, without It is.

  This task is solved by the features of claim 1. Preferred embodiments of the invention are described in the dependent claims. All combinations of at least two of the features described in the description, the claims and / or the drawings are also included within the scope of the present invention. The stated ranges of values are obviously valid within the stated limits as limit values, and any combination may be used.

  The basic idea of the invention is to remove impurities using a directed ion beam in a process chamber before the subsequent processing of the substrate surface of the substrate, wherein this ion beam comprises a first component, in particular a gas. A second component, in particular a gaseous second component, or a working gas, into the process chamber. The second component is used for bonding of the exfoliated impurities. Preferably, the second component is conducted to the process chamber at a constant flow rate to carry out the impurities from the process chamber.

  In the case of the present invention, the first component or the second component in particular comprises a gas mixture or a pure gas, in particular a pure noble gas.

The invention, in other words, cleans the surface of various materials, in particular semiconductor materials, using ion sputtering, in particular low-energy ion sputtering and / or forming gases, at room temperature ( _RT ) or at very low temperatures. Method and apparatus In this case, the temperature is less than 500 ° C., preferably less than 300 ° C., more preferably less than 100 ° C., most preferably room temperature.

The forming gas preferably comprises a hydrogen fraction of more than 20 percent. In this case, the forming gas is preferably interpreted as a gas mixture of argon (Ar) and hydrogen (H ₂ ) or a gas ion mixture of nitrogen (N ₂ ) and hydrogen (H ₂ ). However, it is also conceivable that this forming gas consists only of a single gas component, in particular consisting only of argon or only hydrogen.

  Accordingly, the present invention relates to a method and apparatus for removing impurities from the substrate surface, in particular at the lowest possible temperature, preferably at room temperature, without damaging the substrate surface. This method can preferably be used for low cost cleaning of semiconductors or semiconductor structures. Preferably, the device and method according to the invention are used for the purpose of preparing the substrate surface for subsequent bonding, in particular for permanent bonding.

  The preferred embodiment uses a broadband ion beam for surface cleaning of the substrate surface.

  In the case of the preferred embodiment, this surface cleaning is performed site-selective rather than over the entire surface. This embodiment is used in particular in the fields of optics, optoelectronics and sensor engineering to clean only defined / predetermined areas of the substrate surface. In this case, position selective surface cleaning is performed by a narrow band ion beam generated by direct focusing or by a narrow band ion beam generated by using a stop from a broad band ion beam. Another possibility according to the invention is the masking of the substrate with the photoresist which is correspondingly irradiated and chemically treated. The photoresist is used as a positive or negative mask. Another possibility according to the invention is the use of mechanical shadow masks.

  The idea according to the invention lies in particular in that the ions of the first component are accelerated towards the substrate surface by means of an ion source, in particular by means of a broad beam ion source. The process chamber is additionally purged with a forming gas, or preferably pure hydrogen, as a second component. It is also conceivable to heat, preferably as little as possible, the substrate, in particular via contact with the sample holder. When using a broad beam ion source, chemical contamination (natural oxides, carbon, impurities) on the substrate can be removed by low energy ions (<1000 eV) without adversely affecting the surface of the substrate it can. Another advantage of using a broad beam ion source is to clean the area of the substrate surface, including the very large substrate surface, in the extreme case the entire substrate surface.

  In this case, the invention is based in particular on the use of a low energy ion sputtering device which bombards ions onto the substrate surface. The ions are preferably bombarded at the substrate surface in the case of a broadband ion beam. Broadband ion beam is understood to be an ion beam whose mean diameter is in the range of the order of the diameter of the substrate. In this case, the ratio of the ion beam diameter to the diameter of the substrate is in particular more than 1/100, preferably more than 1/10, more preferably more than 1/2 and most preferably more than 1. The broadband ion beam preferably covers the substrate surface plug.

  If the diameter of the ion beam on the substrate surface is smaller than the diameter of the substrate surface, according to the invention, in order to reach all the positions to be cleaned on the substrate surface, in particular between the ion beam and the substrate surface Relative movement is performed. Preferably, this relative movement is performed by moving the substrate sample holder relative to the ion source. In the case of this embodiment, a position-specific and hence position-resolved cleaning of the substrate surface is possible. In this case, in particular, the use of a narrow band ion beam is conceivable, in which the ratio of the diameter of the ion beam to the diameter of the substrate surface is less than 1, preferably less than 1/10, more preferably less than 1/100. Most preferably, it is adjusted to less than 1/1000. The smaller this ratio, the greater the degradation of the cleaning process, but the longer it takes to clean the corresponding area on the substrate to be cleaned by relative movement. A narrow band ion beam can be focused directly by optics or produced from a broad band ion beam by mask and aperture techniques. This optical element consists in particular of an electrical lens and / or a magnetic lens, which are included in the concept of an optical lens. When using mask and aperture technology, preferably an automation unit, in particular a robot, can be used to quickly replace the mask or the aperture with various numerical apertures. The production of narrow band ion beams by ion sources with correspondingly smaller cross sections is also conceivable.

  Aspects according to the invention, regardless of the ion beam diameter used, use, in particular, low-energy ion sputtering systems in conjunction with corresponding forming gases, in particular pure argon or pure hydrogen gas (second component). It is. This forming gas is used in this case as a process gas for ion generation in the ion source of the ion sputtering apparatus and / or in the process chamber as a purge gas. By the combination according to the invention of the low energy ion sputtering apparatus and the corresponding forming gas, it is ensured that impurities are removed from the substrate surface but the substrate surface is not reformed or damaged at all. Thus, an aspect according to the invention is to accelerate low energy ions towards the substrate surface by means of an ion sputtering device, which energy is not sufficient to cause a noticeable modification or damage of the substrate. This damage is at most very slight and is indicated by the depth region where changes in the substrate's microstructure are detectable. This depth range is in particular less than 10 μm, preferably less than 1 μm, more preferably less than 100 nm, more preferably less than 15 nm, even more preferably less than 7 nm, still more preferably 3 nm, by application of the method and apparatus according to the invention Less than, more preferably less than 1.5 nm, most preferably zero. That is, in the ideal case no damage is caused by ion bombardment.

  The impurities and / or the first component (in particular the forming gas) specifically tailored to the substrate surface react with the sputtered atoms / molecules of the impurities, so that, in the case of the present invention, new to the substrate surface. Deposition is suppressed. The thus formed compound bound by the first component is bound in the process chamber, preferably by suction or by deposition in a vacuum system, so that new deposition on the substrate surface is prevented. The process according to the invention can be optimized and assisted by additionally purging the process chamber with a second component, in particular a forming gas, preferably the same forming gas as the forming gas to be ionized at the ion source. . Particularly preferably, a broadband ion beam can be used to carry out the overall cleaning.

  Embodiments and devices according to the present invention show the possibility of low cost which is effective for removing surface impurities, in particular carbon-containing impurities. Embodiments according to the invention can be applied to essentially all kinds of substrate surfaces, but are particularly effective in particular in the case of substrate surfaces exhibiting very low roughness. This roughness is expressed as arithmetic mean roughness, root mean square height, or ten point mean roughness. The mean values for the arithmetic mean roughness, the root mean square height and the ten point mean roughness are generally differentiated for the measurement area or measurement plane, but in the same order of magnitude. Thus, the following numerical range for roughness is interpreted as the value for arithmetic mean roughness, root mean square height or ten point mean roughness. In the case of the present invention, this roughness is in particular less than 100 μm, preferably less than 10 μm, more preferably less than 1 μm, still more preferably less than 100 nm, most preferably less than 10 nm. Embodiments according to the invention are also suitable, in particular, for the cleaning of substrates finished into optical elements. In addition, it is also possible to clean substrates with functional elements exhibiting relatively complex topography, such as eg diffraction gratings, Fresnel lenses, MEM devices, cavities for housing of LEDs.

  At the same time, the selection of sufficiently low kinetic energy of the ions suppresses the occurrence of damage in the semiconductor material.

  In the case of the first embodiment according to the invention, the device according to the invention comprises at least one high vacuum chamber provided with an additionally connected Kaufmann-type wide beam ion source or RF-wide ion source. (Source: K. Otte, A. Schindler, F. Bigl and H. Schlemm, Rev. Sei. Instrum., 69, 1499 (1998)). In the case of the present invention, the diameter of the broadband ion source is in particular 10 mm to 1000 mm, preferably 20 mm to 800 mm, more preferably 30 mm to 600 mm, more preferably 40 mm to 400 mm.

The ion device according to the invention can be completely evacuated in the case of one embodiment. This kind of evacuation of the process chamber takes place, in particular, before the introduction of the working gas or the second component. The ion device may be evacuated to a pressure of less than 1 bar, preferably less than 10 ^-3 mbar, more preferably less than 10 ^-5 mbar, more preferably less than 10 ^-7 mbar, most preferably less than 10 ^-8 mbar. it can. After this evacuation, the ion device is purged using a working gas. This purge is performed until the working pressure is reached.

The working pressure in the ion chamber is in this case in particular 10 ^-8 mbar to 1 bar, preferably 10 ^-6 mbar to 1 bar, more preferably 10 ^-6 mbar to 1 mbar, most preferably 10 ^-5 mbar to 1 mbar is there.

The working pressure of the second component or working gas is, in particular, 1 × 10 ⁻³ mbar to 8 × 10 ⁻⁴ mbar. 1 to 100 sccm / min (“standard” of a gas mixture (argon containing hydrogen), a gas mixture of (nitrogen containing hydrogen), or pure hydrogen in a broad beam ion source used to clean the substrate surface) Introduce a controlled gas flux of cm ³ / min "=" cm ³ / min at standard conditions ". In a special embodiment, hydrogen, in particular pure hydrogen, is used.

  In a particularly preferred first embodiment, the substrate sample holder is mounted and fixed on a table, which has at least one rotational degree of freedom, preferably at least two rotational degrees of freedom, most preferably Provide three rotational degrees of freedom, arranged perpendicular to each other.

  In a preferred second embodiment, the substrate sample holder is mounted and fixed on a table, which provides a plurality of translational and rotational degrees of freedom. The table can move along at least the X direction and a Y direction perpendicular to the X direction. Preferably, the table also has a degree of freedom in the Z direction which extends perpendicularly to the X and Y directions. In a particularly preferred embodiment, the table has further rotational degrees of freedom, in particular three other rotational degrees of freedom. Thus, the substrate sample holder can travel in all directions and be aligned in all directions within the process chamber. The ion incident angle is defined as the angle between the ion beam (more precisely, the central axis or symmetry axis of the ion beam) and the normal on the substrate surface. The ion incident angle can be freely adjusted between 0 ° (vertical incidence) and 90 ° (parallel incidence to the substrate surface). The ion incidence angle is in particular less than 90 °, preferably less than 70 °, more preferably less than 50 °, still more preferably less than 30 °, most preferably 0 °. Since the ion source is preferably fixed stationary with respect to the process chamber, the ion incidence angle is adjusted by the rotation of the substrate, in particular by the tilt of the substrate sample holder. In the case of the present invention, it is also conceivable, if this is not the case, to also moveable ion sources, and thereby to adjust the corresponding ion incidence angle by the movement of the ion source.

  Due to the use of a special broadband ion source and the fact that this type of ion source allows relatively homogeneous ion bombardment of the whole surface of the substrate, in the case of a special embodiment also a stationary substrate sample holder and / or a stationary table are considered Be done.

  The distance between the substrate sample holder and the outlet opening of the ion source is in particular less than 100 cm, preferably less than 80 cm, more preferably less than 60 cm, most preferably less than 40 cm. In a very special embodiment, the energy of the ions at the substrate surface can be adjusted in relation to the precisely adjusted forming gas density by the distance of the substrate to the outlet opening of the ion source. In particular, for this purpose measuring means are provided for measuring this distance.

  The substrate sample holder can be heated to a temperature of 0 ° C. to 500 ° C. by at least one heater, in particular a plurality of heaters, during the cleaning process. The substrate temperature, particularly in relation to the temperature sensor, is 0 ° C. to 500 ° C., preferably 0 ° C. to 400 ° C., more preferably 0 ° C. to 300 ° C., more preferably 0 ° C. to 200 ° C., most preferably 0 ° C. Adjusted to ~ 250 ° C.

  The substrate sample holder is preferably controllable by a computer and / or a microcontroller and / or firmware and / or corresponding software.

  Particularly preferably, the starting position can be programmed so that the substrate sample holder can scan a given area of the substrate surface fully automatically. Thus, the optimal scanning technique can be stored and recalled by pressing a button. This possibility is particularly useful in order to reach all locations on the substrate surface to be cleaned, in particular when using a narrow band ion source. When using a broadband ion source, movement of the substrate sample holder, in particular linear movement and / or rotational movement, during irradiation of ions can contribute to the homogenization of the effect according to the invention. In this case, high frequency linear motion and rotational motion are particularly preferred. The frequency of the substrate sample holder, ie the frequency at which the substrate sample holder performs in any one direction per second, is in this case in particular more than 1/100, preferably more than 1/10, more preferably more than 1 , More preferably more than 10, most preferably more than 100. The number of revolutions per minute (English: rounds-per-minute rpm) of the substrate sample holder is more than 1/10, preferably more than 1, more preferably more than 10, most preferably more than 100.

Ion Source The internal structure of the ion source preferably used according to the invention corresponds, for example, to the Kaufmann type. The difference lies in particular in the drawer grid system (Extraktionsgittersystem). The ions extracted from the plasma chamber are separated by the application of an HF alternating electric field (20 MHz) in an additional grid system. In this case, the overall transmission is about <20%. This corresponds to an ion current density of 1 to 100 μA / cm ² . For certain applications where large current densities can be used without mass separation, so-called IS-mode (English: Ion-Source-Mode) can be utilized.

In the RAH mode, in addition to the suppression of impurities in the ion beam, the ion source is capable of appropriate selection of specific ion species exhibiting a predetermined charge state. The disadvantage is that low ion energy eV and low ion current density (E _ion <800 eV and J _ion <500 μA / cm ^{2 in} mass mode not separated) or E _ion <500 eV and J _ion <50 μA / cm in mass separated RAH mode ² ) For an accurate description of the mode of functioning of the ion source, reference is made to the corresponding literature (Source: K. Otte, A. Schindler, F. Bigl and H. Schlemm, Rev. Sei. Instrum., 69, 1499 (1998)). Point out.

In one embodiment according to the invention, the ion current density for the ion current immediately after the exit from the ion source is 10 ⁻⁵ μA / cm ² to 10 ⁵ μA / cm ² , preferably 10 ⁻³ μA / cm ^2. ~ 10 ³ μA / cm ² , more preferably 1 μA / cm ^{2 to} 500 μA / cm ² is shown. The corresponding ion current density at the substrate surface is preferably the same as the ion current density of this density. In general, indeed, especially the emission of the ion current also causes an intended or unintended reduction. The ion current density of the ion current at the substrate surface is 10 ⁻⁵ μA / cm ² to 10 ⁵ μA / cm ² , preferably 10 ⁻³ μA / cm ² to 10 ³ μA / cm ² , more preferably 1 μA / cm. ^{2 to} 500 μA / cm ² .

Working gas (first component and / or second component)
In particular, the following types of atoms or molecules are used as working gases:
Forming gas FG (argon + hydrogen) and / or forming gas RRG (hydrogen + argon) and / or forming gas NFG (argon + nitrogen) and / or hydrogen, in particular pure hydrogen, and / or argon Especially pure argon

Device according to the invention This section describes a method of cleaning a substrate surface using a forming gas RFGx (hydrogen percentage 100% to 50% with 0% to 50% Ar). The device according to the invention comprises an ion beam source and a substrate sample holder provided with an optional heater. The substrate is secured to the substrate sample holder. A controlled amount of forming gas is introduced to operate the ion source.

式中、Ｄ⁺は、電離した供与体を表し、かつＡ^-は、電離した受容体を表す。

This gas flow is adjusted in particular to 0.001 to 100000 sccm / min, preferably 0.01 to 10000 sccm / min, more preferably 0.1 to 1000 sccm / min, and most preferably 1 to 100 sccm / min. The pressure in the process chamber depends on the type of gas used and the pump system used, but it is 10 ⁻⁸ mbar to 1 bar, preferably 10 ⁻⁷ mbar to 10 ⁻² bar, more preferably 10 ⁻⁶ mbar to 10 Adjusted to ^-3 bar. The potential difference between the ion source and the substrate surface is in particular adjusted to between 1 V and 5000 V, preferably between 30 V and 2500 V, most preferably between 50 V and 800 V. Ion beam current density at the substrate, in particular, 0.001~5000μA / cm ^2, preferably 0.01~2500μA / cm ^2, more preferably 0.1~1000μA / cm ^2, and most preferably 1~500μA It is in the range of / cm ² . Preferably an ion incidence angle of less than 50 °, preferably less than 40 °, more preferably less than 30 °, more preferably less than 22 ° is used. The irradiation time and heating of the substrate surface depend, inter alia, on the type of semiconductor material used and the thickness of the contamination layer on the surface. The distance of the substrate to the ion source is adjusted to, in particular, 1 to 100 cm, preferably 10 to 80 cm, more preferably 20 to 50 cm, most preferably about 30 cm (measured from the outlet opening of the ion source). The heating of the substrate surface to a predetermined temperature also depends on the type of semiconductor material used. The passivation effect of hydrogen is generally and in the simplest case described by the following chemical reaction (Source: by AJ Pearton and JW Lee, vol. 61, edited by NH Nickel (Academic press, San Diego) p. 442 (1999)):

Where D ⁺ represents an ionized donor and A ⁻ represents an ionized acceptor.

In the case of a special embodiment according to the invention, a plurality, in particular more than one, preferably more than two, more preferably more than three ion sources are connected to the process chamber, in particular to the high vacuum ion chamber. be able to. The use of multiple ion sources can, on the one hand, increase and better control the ion density at the surface of the substrate. Furthermore, the plurality of ion sources can also use a plurality of different ion species, which differ from one another during production and only after leaving the ion source, in particular at the substrate surface. Or meet for the first time just before the substrate surface. The method according to the invention can be used for the cleaning of all types of substrate surfaces. Particularly preferably, this method is, of course, suitable for cleaning substrate surfaces consisting of the following materials / material combinations:
Silicon, thermally oxidized silicon, quartz, Zerodur, silicon carbide, molybdenum and / or 3A-5B semiconductor materials,
For special applications:
○ Similar semiconductor structures and / or ○ direct bonding of wafers ○ GaAs / GaAs, InP / InP, Ge / Ge, Si / Si, Si, SiO ₂ and / or different semiconductors during direct bonding of wafers Structure and / or GaAs GaAs / InP, GaAs / Ge, GaAs / Si, Ge / Si, Ge / Si, Ge / InP, InP / Si and / or 及 び metal and / or ○ Cu, Al, W, Mo, Ag, Au, Pt , Zn, Ni, Co and / or ○ Alloys and / or ○ Optional combinations of the above-mentioned materials, in particular

After the substrate surface has been cleaned according to the present invention, it can be supplied to subsequent process steps. Lithographic processes, such as imprinting processes or photolithography, coating processes, etching processes, wet chemical cleaning processes and / or vacuum deposition processes are conceivable. Among the preferred vacuum deposition processes according to the invention are in particular:
Physical vapor deposition (PVD),
・ Chemical vapor deposition (CVD),
・ Molecular beam epitaxy (MBE),
Plasma Chemical Vapor Deposition (PECVD),
Plasma Physical Vapor Deposition (PEPVD),
Atomic layer deposition (ALD).

  Particularly preferably, the method according to the invention is suitable for cleaning the substrate surface in preparation for the subsequent bonding operation of the second substrate with the second substrate surface. In particular, in the case of a permanent bonding process such as a metal bonding process or a fusion bonding process, both substrate surfaces are preferably of extremely high purity and flatness in order to allow good bonding of both substrate surfaces. Indicates Any kind of impurity critically disrupts this bonding process. The second substrate surface is preferably cleaned / cleaned in the same manner. Direct bonding is particularly preferred. On contact of two metal surfaces treated according to the invention, preferably a permanent bonding takes place automatically. In the case of substrate surfaces, such as silicon or silicon oxide, for example, so-called preliminary bonding can first be carried out and this preliminary bonding can also be converted into a permanent bonding by a subsequent heat treatment process. The preparation of the preliminary bond is preferably performed at room temperature. In a further particularly preferred embodiment, the substrate surface is pure enough to reduce the temperature required for the production of the permanent bond to a minimum. In the ideal case, the production of a permanent bond is performed on all kinds of substrate surfaces immediately and without preliminary bonding steps, in particular without additional heat treatment steps.

A direct bond is in this case taken to be a bond of the two substrate surfaces only by (atomic) covalent bonds. In the first stage, the formation of a so-called preliminary bond takes place, which is characterized by the still reversible and thus releasable bond caused by the van der Waals forces between both substrate surfaces. If both substrate surfaces are connected to each other once by preliminary bonding, at least further or new contamination of these substrate surfaces is no longer possible. This preliminary bonding can subsequently be transformed by heat treatment into a permanent, ie irreversible, non-releasable direct bonding. This direct bonding is characterized in particular by the formation of covalent bonds between the substrate surfaces. This covalent bond is in particular a covalent bond of Si-Si or Si-O. Thus, the described embodiments and apparatus according to the invention are used in particular for processes in which two substrates have to be joined at least once with each other. Thus, particularly preferably, the device according to the invention is part of a vacuum cluster, preferably a high vacuum cluster, more preferably an ultra high vacuum cluster, and in which the substrate is cleaned in a corresponding process and It is used in particular in connection with alignment devices and / or bonding devices in order to prepare for bonding. The pressure in the above-mentioned vacuum cluster is in particular less than 1 bar, preferably less than 10 ^-1 mbar, more preferably less than 10 ^-3 mbar, more preferably less than 10 ^-5 mbar, most preferably less than 10 ^-8 mbar .

  The method according to the invention can also be used for surface cleaning of substrates which are connected to one another by metal bonding, in particular by diffusion bonding, eutectic bonding, anodic bonding or any other bonding. Thus, in particular, the method according to the invention can also be used for cleaning metal and / or ceramic surfaces.

  The device according to the invention is particularly preferably used for aligning the surfaces of the substrates to be mutually aligned by means of an alignment device (English: aligner) in the same vacuum cluster and to be bonded together by means of a bonding device. The alignment device is in this case, for example, as described in Austrian Patent Invention No. 405,775, Patent Cooperation Treaty / European Patent Application 2013/062473 or Patent Cooperation Treaty / European Patent Application 2013/07583 It can be an alignment device, and in this respect these documents are pointed out. Particularly preferably, the substrate is fixed by a magnetic member between the alignment device and the bonding device. A fixation device of this kind is described in detail in the Patent Cooperation Treaty / European Patent Application No. 2013/056620 in the patent literature, to which reference is made in this respect.

Examples of Surfaces to be Cleaned The following section presents a plurality of optimal parameter sets which result in the complete removal of impurities, in particular carbon-containing impurities and native oxides, in the case of the mentioned substrate surfaces.

GaAs Substrate Surface The process according to the invention is mainly but not exclusively used for oxide removal in the case of a GaAs surface.

The working gas used for the GaAs surface is the forming gas RFG1 (100% hydrogen) or RFG2 (see Table 1). The ion energy is in this case 100 eV to 500 eV, preferably 200 eV to 400 eV, most preferably just 300 eV. The current density is 2.5 μA / cm ^{2 to} 6.5 μA / cm ² , preferably 3.5 μA / cm ^{2 to} 5.5 μA / cm ² , more preferably just 4.5 μA / cm ² . The temperature of the substrate surface is 100 ° C. to 200 ° C., preferably 125 ° C. to 175 ° C., more preferably just 150 ° C. The treatment time of the substrate surface is more than 10 s, preferably more than 50 s, more preferably more than 100 s, most preferably more than 300 s. The ion dose of the ions is 10 ¹² ions / cm ^{2 s to} 10 ¹⁶ ions / cm ² s, more preferably 10 ¹³ ions / cm ^{2 s to} 10 ¹⁵ ions / cm ² s, most preferably just 1.5 · 10 ^{It is 14} ions / cm ² s.

The mechanism of oxide removal on the GaAs surface by H ion bombardment is probably based on the chemical reaction between hydrogen ions or radical hydrogen and arsenic oxide. The resulting arsenic oxide evaporates under vacuum. The corresponding chemical reaction is shown below:

  In this case, χ = 3 or 5, which corresponds to various oxides of arsenic on the GaAs surface. This electron is derived from the neutralization or conduction band of the "voltageless sample" (Source: E. Petit, F. Houzay and J. Moison, J. Vac. Sei. Technol. A 10, 2172 (1992) ).

A corresponding event is expected during the purification of gallium oxide.

Sublimation of Ga ₂ O is likewise an important step for the removal of Ga oxides from the substrate surface. It is also conceivable that at low temperatures, in particular at temperatures below 200 ° C., no sublimation of Ga ₂ O takes place and that reduction of gallium arsenide by atomic hydrogen takes place. This produces gallium and water, which evaporates accordingly.

Ge substrate surface The process according to the invention is mainly used for oxide removal and cleaning of organic compounds in the case of germanium surface.

The working gases used for the Ge surface are the forming gas mixtures RFG1, RFG3, RFG4 and RFG5 (see Table 1). The ion energy is in particular 100 eV to 800 eV, preferably 150 eV to 400 eV, most preferably just 350 eV, 200 eV, 400 eV (see Table 2). Current ^{density, 4.5μA / cm 2 ~8.5μA / cm} 2, preferably ^{5.5μA / cm 2 ~7.5μA / cm 2} , and most preferably just 6.5μA / cm ^2. The temperature of the substrate surface is 275 ° C. to 350 ° C., preferably 300 ° C. to 325 ° C., most preferably just 300 ° C. The treatment time of the substrate surface is in particular more than 10 s, preferably more than 300 s, more preferably more than 600 s, most preferably more than 1200 s. The ion dose of the plasma is in particular 10 ¹² ions / cm ^{2 s to} 10 ¹⁶ ions / cm ² s, more preferably 10 ¹³ ions / cm ^{2 s to} 10 ¹⁵ ions / cm ² s, most preferably just 5 × 10 ^{It is 14} ions / cm ² s.

Complete removal of native oxide and carbon from the Ge surface was achieved by ion bombardment with the process parameters of Table 2, except for a relatively low percentage (<1%) that may be due to impurities in the process chamber. When the surface temperature is increased from room temperature to about 350 ° C., carbon and oxide films can be completely removed from the germanium substrate surface. Possible chemical reactions for the removal of germanium oxide by a hydrogen ion beam can be described next:

InP Substrate Surface The process according to the invention is mainly but not exclusively used for oxide removal in the case of InP surface.

The working gases used for the InP surface are the forming gas mixtures RFG1, RFG3 and NFG5 (50% nitrogen + 50% argon). The ion energy is 100 eV to 500 eV, preferably 200 eV to 400 eV, most preferably just 300 eV. The current density is 2.5 μA / cm ^{2 to} 6.5 μA / cm ² , preferably 3.5 μA / cm ^{2 to} 5.5 μA / cm ² , more preferably just 4.5 μA / cm ² . The temperature of the substrate surface is 125 ° C to 225 ° C, preferably 150 ° C to 200 ° C, more preferably just 175 ° C. The treatment time of the substrate surface is more than 10 s, preferably more than 100 s, more preferably more than 300 s, most preferably more than 600 s. The ion dose of plasma is 10 ¹² ions / cm ^{2 s to} 10 ¹⁶ ions / cm ² s, more preferably 10 ¹³ ions / cm ^{2 s to} 10 ¹⁵ ions / cm ² s, most preferably just 1.5 × 10 10 ^{It is 14} ions / cm ² s.

Si Substrate Surface The working gases used for the silicon surface are the forming gas mixtures FG0, FG1, FG3, RFG5, NFG3 (see Table 1). The ion energy is between 150 eV and 800 eV, preferably between 150 eV and 500 eV, most preferably just 500 eV. Current ^{density, 20μA / cm 2 ~70μA / cm} 2, preferably not ^{30μA / cm 2 ~60μA / cm 2} , more preferably at ^{40μA / cm 2 ~50μA / cm 2} . The temperature of the substrate surface is 300 ° C to 400 ° C, preferably 325 ° C to 375 ° C, more preferably just 350 ° C. The treatment time of the substrate surface is more than 10 s, preferably more than 50 s, more preferably more than 100 s, most preferably more than 300 s. The ion dose of plasma is 10 ¹³ ions / cm ^{2 s to} 10 ¹⁷ ions / cm ² s, more preferably 10 ¹⁴ ions / cm ^{2 s to} 10 ¹⁶ ions / cm ² s, most preferably just 1.5 · 10 ^{It is 15} ions / cm ² s.

The removal of silicon oxide is preferably described by the following reaction formula:

The working gases used for thermally oxidized silicon oxide on SiO ₂ substrate surfaces are the forming gas mixtures FG 0, FG 2, FG 5 (see Table 1). The ion energy is between 150 eV and 800 eV, preferably between 475 eV and 525 eV, most preferably just 500 eV. Current ^{density, 20μA / cm 2 ~70μA / cm} 2, preferably not ^{30μA / cm 2 ~60μA / cm 2} , more preferably at ^{40μA / cm 2 ~50μA / cm 2} . The temperature of the substrate surface is 300 ° C. to 400 ° C., preferably 325 ° C. to 375 ° C., most preferably just 350 ° C. The treatment time of the substrate surface is more than 10 s, preferably more than 50 s, more preferably more than 100 s, most preferably more than 300 s. The ion dose of plasma is 10 ¹³ ions / cm ^{2 s to} 10 ¹⁷ ions / cm ² s, more preferably 10 ¹⁴ ions / cm ^{2 s to} 10 ¹⁶ ions / cm ² s, most preferably just 1.5 · 10 ^{It is 15} ions / cm ² s.

The removal of silicon oxide is preferably described by the following reaction formula:

Zerodur (Zerodur (AlSiO ₂₎₎ surface aluminum oxide working gas used for silicon is forming gas mixture FG5 (50% argon and hydrogen 50%) (see Table 1). The ion energy is 450eV to 550eV, preferably 475eV to 525eV, most preferably just 500eV. Current ^{density, 5μA / cm 2 ~500μA / cm} 2, preferably from ^{30μA / cm 2 ~60μA / cm 2} , and most preferably just 500μA / cm ^2. The temperature of the substrate surface is from room temperature to 400 ° C., most preferably just at room temperature. The treatment time of the substrate surface is more than 10 s, preferably more than 50 s, more preferably more than 100 s, most preferably more than 120 s. The ion dose of plasma is 10 ¹³ ions / cm ^{2 s to} 10 ¹⁷ ions / cm ² s, more preferably 10 ¹⁴ ions / cm ^{2 s to} 10 ¹⁶ ions / cm ² s, most preferably just 1.5 · 10 ^{It is 15} ions / cm ² s.

  The quantification of the substrate surface before and after treatment according to the invention was performed by X-ray photoelectron spectroscopy (XPS).

General Description of the Process According to the Invention The process according to the invention can be controlled in particular as follows:
A first gas, in particular a forming gas, more preferably a forming gas consisting of only two components, most preferably argon, is ionized in an ion source and accelerated to a point on the substrate surface by an acceleration unit. In the case of the preferred use of a broadband ion beam, this ion beam in particular covers the entire substrate. The first component strikes uncontaminated areas of the substrate surface and is flexibly controlled, and thus does not cause modification / damage in the substrate surface, and thereby physical and / or chemical changes Not cause. In the second case, the first component is an impurity. The binding energy between the impurities and the substrate surface is, in the case of the invention, adjusted to a lower energy, in particular to a fraction of that required for the change of the substrate surface itself. Alternatively or additionally, the binding energy between the impurity and the substrate surface is adjusted to a lower, in particular a fraction, than the kinetic energy of the first component. Therefore, the first component can remove impurities from the substrate surface without damaging the substrate surface itself. In a second step according to the invention, a second gas, in particular a forming gas, more preferably a forming gas consisting of preferably only one component, preferably hydrogen, is less harmful to the sputtered impurities present in the atmosphere. Not used to convert into compounds that are no longer easily deposited on the substrate surface. This compound is preferably a compound which is present in gaseous form in the corresponding ambient environment and can therefore be removed from the process chamber. The gas produced in the ion source may, in the case of a special embodiment, be the same as the second gas, which converts the impurities into less harmful compounds that are no longer easily deposited on the substrate surface.

Furthermore, an apparatus according to the invention is shown to which the method according to the invention can be applied as effectively as possible. The device according to the invention comprises at least one ion source, at least one process chamber, at least one valve for introducing a working gas into the process chamber, and a substrate sample holder for fixing the substrate and in particular for movement. It consists of The device according to the invention is preferably part of a cluster, more preferably part of a high vacuum cluster, more preferably part of an ultra high vacuum cluster. The pressure in the above-mentioned vacuum cluster is in particular less than 1 bar, preferably less than 10 ^-1 mbar, more preferably less than 10 ^-3 mbar, more preferably less than 10 ^-5 mbar, most preferably less than 10 ^-8 mbar . In a further particularly preferred embodiment, the device according to the invention is used in particular together with a bonding device and / or an alignment device to bond the substrates to one another.

Furthermore, substrates characterized by extremely high surface purity and extremely low damaged surface area are shown as products according to the invention. This surface purity is in this case preferably represented by the ratio of impurity atoms to the number of substrate surface atoms. The surface purity is thus a dimensionless ratio number. Preferably this number is a very small number and is therefore expressed in ppm (English: parts per million), ppb (English: parts per billion) or ppt (English: parts per trillion). Prior to the cleaning process according to the invention, the entire substrate surface is covered with impurities, whereby the surface units defined above may be one or more. This surface purity is correspondingly reduced by the method according to the invention. Impurities on the substrate surface, after applying the method according to the invention, 1 (10 ⁶ ppm), preferably less 10 ^-3 less than (1000 ppm), more preferably 10 ^-6 less than (1 ppm), more preferably 10 ^- Less than ⁹ (1 ppt), particularly preferably zero.

  The strength of the damage is most preferably indicated by the depth region where the change in the microstructure of the substrate is still detectable. This depth region is less than 10 μm, preferably less than 1 μm, more preferably less than 100 nm, more preferably less than 10 nm, more preferably less than 1 nm, most preferably zero, by application of the method and apparatus according to the invention. That is, in the ideal case no damage is caused by ion bombardment. The detection of such damage is not carried out by the method according to the invention, but preferably from the same batch, the microstructures of the surface or the near-surface area of the first substrate treated by the method according to the invention This can be done by comparing with the microstructure of the surface or the near surface area of the two substrates. The microstructure is in this case preferably by means of TEM (transmission electron microscopy) and / or AFM (English: atomic force microscopy) and / or SEM (English: scanning electron raicroscopy) and / or X-ray scattering and / or electron scattering. Be investigated.

  Other advantages, features and details of the invention will be apparent from the following description of preferred embodiments and from the drawings.

Fig. 1 represents a schematic view of a first embodiment according to the invention. Fig. 2 represents a schematic view of a second embodiment according to the invention. Fig. 3 represents a schematic view of a third embodiment according to the invention. Fig. 4 represents a schematic view of a fourth embodiment according to the invention. It represents an academic graph of concentration dependence of processing time of multiple atoms. Fig. 3 represents an academic graph of the wavelength dependence of the XPS signal on silicon material. Fig. 6 represents a microscopic surface picture of a substrate surface before treatment according to the invention. Figure 2 represents a microscopic surface picture of a substrate surface after treatment according to the invention. Fig. 6 represents an academic graph of the wavelength dependence of the XPS signal on silicon oxide material. Fig. 6 represents an academic graph of the wavelength dependence of the XPS signal with respect to Zerodur material. Fig. 6 represents an academic graph of the wavelength dependence of the XPS signal on gold material.

  In the figures, identical or similarly acting features are denoted by the same reference numerals.

  FIG. 1 shows a first preferred embodiment according to the invention consisting of an ion sputtering device 1 provided with an ion source 2 for producing an ion beam 3, in particular a broadband ion beam. The ion beam 3 strikes the substrate surface 7 o of the substrate 7 fixed to the substrate sample holder 5. The substrate sample holder 5 is fixed to the table 4 and preferably replaceable. The substrate 7 can be introduced into the process chamber 8 via the gate 9 by a robot. The process chamber 8 can be evacuated and / or purged with process gas via the valve 6. The substrate surface 7o can be moved by translation of the table 4 in the x and / or y and / or z directions and / or rotational movement about the x and / or y and / or z axes. It can be at any position and any direction with respect to the ion beam 3.

  The process gas is preferably the same forming gas used by the ion source 2 to produce the ion beam 3.

  FIG. 2 shows a second embodiment in which the second ion source 2 'is expanded. This second ion source 2 ′ can be used to introduce a second forming gas into the process chamber 8 or this second ion source 2 ′ can be adapted by the ion beam 3 ′ of the ion beam 3. Available for operation. For example, a second ion gas is produced in a second ion source 2 'and the second ion gas reduces or oxidizes the ions in the ion beam 3 of the first ion source 2 It is conceivable to manipulate the ion density in 3 by means of the ion beam 3 '. It is also conceivable that the second ion source 2 'is an electron source, and the electron source is used to shoot electrons toward the ion beam 3. Then, the electrons of the ion beam 3 'reduce the positively charged ions of the ion beam 3. The high electron density can also enhance the oxidation state of the ions of the ion beam 3, so that the ions are negatively charged.

  FIG. 3 shows a third embodiment according to the invention, similar to FIG. 1, in which the ion source 2 ′ ′ cleans the substrate surface 7o according to the invention using a narrow band ion beam 3 ′ ′. Conduct. In order to reach the overall desired position at the substrate surface 7o, the substrate sample holder 5 is moved relative to the ion beam 3 '"together with the substrate 7. Even in this embodiment, at least one other ion source 2'. The use of

  FIG. 4 shows a fourth embodiment according to the invention, similar to FIGS. 2 and 3, in which the ion source 2 produces a broadband ion beam 3 above the aperture. The diaphragm 10 converts this broadband ion beam 3 into a narrow band ion beam 3 '. The second ion source 2' is not only for the manipulation of the ion beam 3 ', in the case of the embodiment according to the invention. Particularly preferably, it is combined with the impurities which are particularly detached from the throttle 10. Otherwise, this impurity may be deposited on the substrate 7 and contaminate the substrate 7. This combination of the ion source 2, the broadband ion beam 3 and the diaphragm 10, shown in FIG. 4, is used very frequently for the production of the corresponding narrow band ion beam 3 '", according to this embodiment according to the invention Correspondingly, there is a high technical significance and a high economic significance .. The throttling 10 is, in particular, made of carbon or a carbon-containing material and is thus deeply involved in accordance with the contamination of the substrate 7, in particular with organic matter. However, according to this embodiment according to the invention, the deposition of impurities by means of the diaphragm 10 can be sufficiently suppressed, in particular by means of the second ion source 2 'configured as an ion gun and / or the introduced forming gas, Alternatively, the ion beam 3 'of the second ion source 2' can be completely removed during the corresponding positioning of the stop 10 '. , I.e. in the region of the broadband ion beam 3. In a further particularly preferred embodiment, the ion source 2 'can be used with the ion beam 3' above and below the diaphragm 10. Of course, the ion beam 3 'can also be used in the direction of the substrate surface 7o in order to reach the overall desired position on the substrate surface 7o, also the substrate sample The holder 5 can be moved relative to the ion beam 3 ′ ′ with the substrate 7.

  FIG. 5 shows an academic graph of the carried out XPS (X-ray photoelectron spectroscopy) measurements, which is an ion sputtering according to the invention of atomic concentrations of gallium, arsenic, carbon and oxygen at the GaAs substrate surface 7 o The apparatus and the invention are described as a function of impact time with a forming gas mixture according to the invention. It can be clearly recognized that the oxygen concentration and the carbon concentration decrease and in connection therewith the gallium concentration and the arsenic concentration increase. In this case, it is considered that the cleaning process presented here enables such a result at extremely low temperatures and in a very short time, without appreciable damage of the substrate surface. In particular, damage in particular is to be understood as a change in microstructure within the depth region. This depth region is in particular less than 15 nm, preferably less than 7 nm, more preferably less than 3 nm, most preferably less than 1.5 nm.

  FIG. 6a shows an academic graph of the carried out XPS (X-ray photoelectron spectroscopy) measurements of the two intensity spectra. The upper intensity spectrum shows the presence of oxygen and carbon, as well as silicon, with a characteristic intensity profile. In the lower intensity spectrum recorded after the inventive cleaning of the silicon surface, the characteristic oxygen profile and the carbon profile have disappeared. 6 b and 6 c show AFM (atomic force microscopy) photographs of the substrate surface investigated before and after application of the method according to the invention. The reduction of roughness due to the removal of carbon impurities and the removal of oxides is clearly recognizable. The method according to the invention, despite using ion sputtering techniques, does not cause surface roughening, removes impurities and optimally prepares the substrate surface for the subsequent process steps.

  FIG. 7 shows an academic graph of the conducted XPS (X-ray photoelectron spectroscopy) measurements of the three intensity spectra. The upper intensity spectrum shows the presence of carbon as well as oxygen of silicon dioxide. In the first test, it was tried to remove carbon by pure argon. After ion bombardment with pure argon, a second, central intensity profile was recorded. In the case of the second intensity profile, an increase in the carbon concentration can be clearly recognized. This rise in carbon concentration has many causes. However, it is important that this carbon originates from the process chamber 8. The carbon collects in the process chamber 8, deposits on the wall, and is brought in through the members of the ion sputtering apparatus or through the gate. Only with the inventive treatment of the substrate surface 7o according to the inventive technique in the context of the inventive forming gas, one clearly recognizes the absence of a carbon profile with the third lower intensity profile at the same wavelength. Such a carbon-free substrate surface is provided.

  Similar considerations apply, according to FIG. 8, to the test performed on Zerodur.

  FIG. 9 finally shows the removal of carbon at the gold surface. This may prove that the device and method according to the invention are also very suitable for cleaning metal surfaces. Particularly preferably, the method according to the invention can also be used for cleaning metal surfaces, such as copper, in order to bond in the next process step.

Reference Signs List 1 ion sputtering apparatus 2,2 ', 3 "ion source 3,3', 3" ion beam 4 table 5 substrate sample holder 6 valve 7 substrate 7o substrate surface 8 process chamber 9 gate 10 diaphragm

Claims (9)

next:
Placing the substrate surface (7o) in the process chamber (8),
-Made by an ion beam source (2, 2 ', 2 ") on the substrate surface (7o) to remove impurities from the substrate surface (7o) and directed to the substrate surface (7o), Applying an ion beam (3,3 ′, 3 ′ ′) containing the first component,
-Introducing a second component into the process chamber (8) for bonding of the stripped off impurities,
A method of surface treating a substrate surface (7o) of a substrate (7). The process chamber (8) is evacuated prior to the introduction of the second component, in particular less than 1 bar, preferably less than 10 ^-3 bar, more preferably less than 10 ^-5 bar, even more preferably less than 10 ^-7 bar The method according to claim 1, wherein the pressure is exhausted to a pressure less than 10 ^-8 bar, more preferably. The ion beam (3,3 ′, 3 ′ ′) is applied to the substrate surface (7o) at 0.001 to 5000 μA / cm ² , preferably 0.01 to 2500 μA / cm ² , more preferably 0.1 to 1000 μA. The method according to claim 1 or 2, wherein the ion beam density is adjusted to hit at an ion beam density of 1 / cm ² , most preferably 1 to 500 μA / cm ² .   The method according to any one of the preceding claims, wherein the ion beam (3, 3 ', 3 ") is formed as a broadband ion beam, in particular for capturing the entire substrate surface (7o).   The diameter of the ion beam (3,3 ′, 3 ′ ′) striking the substrate surface (7o) with the ion beam (3,3 ′, 3 ′ ′) is larger than 1/100 of the diameter of the substrate surface (7o) 5. A method according to any one of the preceding claims, in particular adjusted to be greater than 1/10 and preferably greater than 1/2.   A second ion beam (3,3 ', 3', 3 ') produced by the second ion beam source (2') on the substrate surface (7o) and / or the first ion beam (3,3 ', 3' ') 6. A method according to any one of the preceding claims, wherein 3 '"is applied.   The method according to any of the preceding claims, wherein the first component and / or the second component are introduced in gaseous form into the process chamber (8).   Preferably, the substrate (7) is translated to the substrate sample holder (5), in particular to the substrate sample holder (5) capable of translational and / or rotational movement, preferably in X, Y and Z directions. The method according to any of the preceding claims, wherein the method is fixed to a rotationally movable substrate sample holder (5). A process chamber (8) for receiving the substrate (7);
-An ion beam source for producing an ion beam (3,3 ', 3 ") comprising a first component, directed to said substrate surface (7o), for stripping impurities from the substrate surface (7o) (2, 2 ', 2 "),
-Means for introducing a second component into said process chamber (8) for bonding of said stripped off impurities;
An apparatus for surface treatment of the substrate surface (7o) of the substrate (7).

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