Abstract
A method for the surface treatment of a substrate surface of a substrate with the following steps: arrangement of the substrate surface in a process chamber, bombardment of the substrate surface with an ion beam, generated by an ion beam source and aimed at the substrate surface, to remove impurities from the substrate surface, whereby the ion beam has a first component, introduction of a second component into the process chamber to bind the removed impurities. A device for the surface treatment of a substrate surface of a substrate with: a process chamber for receiving the substrate, an ion beam source for generating an ion beam that has a first component and is aimed at the substrate surface to remove impurities from the substrate surface, means to introduce a second component into the process chamber to bind the removed impurities.
Claims
1-9. (canceled)
10. Method for the surface treatment of a substrate surface of a substrate, the method comprising: arranging the substrate surface in a process chamber; bombarding the substrate surface with an ion beam, with an ion energy <1000 eV generated by an ion beam source and aimed at the substrate surface, to remove impurities from the substrate surface, wherein the ion beam has a first component; and introducing a second component into the process chamber to bind the removed impurities, wherein the second component is argon and/or hydrogen and/or nitrogen.
11. Method according to claim 10, wherein the method further comprises: evacuating the process chamber before introducing the second component.
12. Method according to claim 11, wherein the process chamber is evacuated to a pressure of less than 1 bar.
13. Method according to claim 10, wherein the method further comprises: adjusting the ion beam such that the substrate surface is bombarded with an ion beam density between 0.001 and 5000 A/cm.sup.2.
14. Method according to claim 10, wherein the ion beam is configured as a broad-band ion beam.
15. Method according to claim 14, wherein the ion beam hits the entire substrate surface.
16. Method according to claim 10, wherein the method further comprises: adjusting the ion beam such that a diameter of the ion beam striking the substrate surface is larger than 1/100 of a diameter of the substrate surface.
17. Method according to claim 10, wherein the method further comprises: bombarding the substrate surface and/or the first ion beam with a second ion beam generated by a second ion beam source.
18. Method according to claim 10, wherein the first and/or the second component is/are introduced into the process chamber in gas form.
19. Method according to claim 10, wherein the method further comprises securing the substrate on a substrate sample holder that is translationally and/or rotationally movable.
20. Method according to claim 19, wherein the substrate holder is translationally and/or rotationally moveable in X, Y and Z directions.
21. Device for the surface treatment of a substrate surface of a substrate, the device comprising: a process chamber for receiving the substrate; an ion beam source for generating an ion beam with an ion energy <1000 eV that has a first component and is aimed at the substrate surface to remove impurities from the substrate surface; and means for introducing a second component into the process chamber to bind the removed impurities, wherein the second component is argon and/or hydrogen and/or nitrogen.
Description
[0106] Further advantages, features, and details of the invention will become clear from the following description of preferred embodiment examples with the aid of the drawings.
[0107] FIG. 1 shows: a schematic depiction of a first embodiment according to the invention,
[0108] FIG. 2 shows: a schematic depiction of a second embodiment according to the invention,
[0109] FIG. 3 shows: a schematic depiction of a third embodiment according to the invention,
[0110] FIG. 4 shows: a schematic depiction of a fourth embodiment according to the invention,
[0111] FIG. 5 shows: a scientific diagram of the concentration dependence of multiple atoms on treatment time,
[0112] FIG. 6a shows: a scientific diagram of the intensity dependence of an XPS signal on the wavelength for the material silicon,
[0113] FIG. 6b shows: a microscopic surface image of a substrate surface before the treatment according to the invention,
[0114] FIG. 6c shows: a microscopic surface image of a substrate surface after the treatment according to the invention,
[0115] FIG. 7 shows: a scientific diagram of the intensity dependence of an XPS signal on the wavelength for the material silicon oxide,
[0116] FIG. 8 shows: a scientific diagram of the intensity dependence of an XPS signal on the wavelength for the material Zerodur, and
[0117] FIG. 9 shows: a scientific diagram of the intensity dependence of an XPS signal on the wavelength of the material gold.
[0118] In the figures, equal or effectively equal features are labelled with the same reference signs.
[0119] FIG. 1 shows a first, preferred embodiment according to the invention, comprising an ion sputtering system 1 with an ion source 2 that generates an ion beam 3, especially a broad-band ion beam. This beam encounters the substrate surface 7o of a substrate 7, which has been secured on a substrate sample holder 5. The substrate sample holder 5 has been secured on a table 4 and is preferably exchangeable. The substrate 7 can, by means of a robot, be loaded via a gate 9 into the process chamber 8. The process chamber 8 can be evacuated and/or flushed with a process gas via a valve 6. Because the table 4 is capable of translational and/or rotational movement in the direction of x and/or y and/or z or about the x- and/or y- and/or z-axis, the substrate surface 7o can be arranged in any arbitrary position and orientation with regard to the ion beam 3.
[0120] The process gas is preferably the same forming gas that is used by the ion source 2 to generate the ion beam 3.
[0121] FIG. 2 shows a second embodiment, expanded by a second ion source 2. The second ion source 2 can either be used to introduce a second forming gas into the process chamber 8 or ensures the targeted manipulation of the ion beam 3 via the ion beam 3. It would be conceivable, for example, to manipulate the ion density in the ion beam 3 by means of the ion beam 3 by generating a second ion gas in the second ion source 2 that reduces or oxidizes the ions in the ion beam 3 of the first ion source 2. It is also conceivable for the ion source 2 to be an electron source, with whose help electrons are shot at the ion beam 3. The electrons of the ion beam 3 then reduce the positively charged ions of the ion beam 3. By means of high ion densities, an increase in the oxidation level of the ions of the ion beam 3 can occur; the ions are therefore more negatively charged.
[0122] FIG. 3 shows a third embodiment according to the invention, similar to FIG. 1, in which an ion source 2 uses a narrow-band ion beam 3, in order to perform the cleaning of the substrate surface 7o according to the invention. In order to reach all desired points on the substrate surface 7o, the substrate sample holder 5 with the substrate 7 is moved relative to the ion beam 3. The use of at least one further ion source 2 is conceivable in this embodiment as well.
[0123] FIG. 4 shows a fourth embodiment according to the invention, similar to FIGS. 2 and 3, in which the one ion source 2 generates a broad-band ion beam 3 above an aperture 10. The aperture 10 converts the broad-band ion beam 3 into a narrow-band ion beam 3. In this embodiment according to the invention, the second ion source 2 not only serves to manipulate the ion beam 3, but also binds especially preferably above all impurities that detach from the aperture 10. These impurities would otherwise deposit on the substrate 7 and contaminate it. Because the combination depicted in FIG. 4 of an ion source 2, a broad-band ion beam 3, and an aperture 10 is often used to generate corresponding narrow-band ion beams 3, this embodiment according to the invention possesses appropriately high technical and economic relevance. The aperture 10 is especially made of carbon or carbon-containing material and is thus correspondingly greatly involved in an especially organic pollution of the substrate 7. By using the embodiment according to the invention, however, and with the help of the second ion source 2, especially configured as an ion gun, and/or the forming gas introduced, depositing of the impurities by the aperture 10 can be mostly prevented or even completely ruled out. The ion beam 3 of the second ion source 2 can, with an appropriate positioning of the aperture 10, also be employed between the aperture 10 and the first ion source 2, meaning in the area of the broad-band ion beam 3. In an exceptionally preferred embodiment, the ion source 2 can be pivoted such that the ion beam 3 can be employed both above and below the aperture 10. The ion beam 3 can, of course, also be further used to clean the substrate surface 7o. In order to reach all desired points on the substrate surface 7o, the substrate sample holder 5 can again be moved with the substrate 7 relative to the ion beam 3.
[0124] FIG. 5 shows a scientific diagram of an XPS (X-ray photoelectron spectroscopy) measurement, in which the atomic concentrations of gallium, arsenic, carbon, and oxygen on a GaAs substrate surface 7o are depicted as a function of bombardment time with the forming gas mixture according to the invention and the ion sputtering system according to the invention. The decrease in oxygen and carbon concentrations as well as the associated increase in gallium and arsenic concentrations are distinctly discernable. Note that the cleaning process presented here makes possible such results at extremely low temperatures and in a very short amount of time, as well as without any noteworthy damage to the substrate surface. In particular, noteworthy damage is understood to mean a change in the microstructure inside of a depth range. The depth range is especially less than 15 nm, preferably less than 7 nm, more preferably less than 3 nm, and most preferably less than 1.5 nm.
[0125] FIG. 6a shows a scientific diagram of an XPS (X-ray photoelectron spectroscopy) measurement of two intensity spectra. The upper intensity spectrum shows the existence of oxygen and carbon as well as silicon through characteristic intensity profiles. In the lower intensity spectrum, recorded after the cleaning of the silicon surface according to the invention, the characteristic oxygen and carbon profiles have disappeared. FIGS. 6b and 6c show an AFM (atomic force microscopy) recording of the substrate surface under examination before and after the use of the methods according to the invention. The reduction of roughness via removal of carbon impurities as well as the removal of the oxide is clearly discernable. Despite the use of ion sputtering technology, the method according to the invention did not, therefore, lead to a roughening of the surface, but rather eradicated the impurities and optimally prepared the substrate surface for a further process step.
[0126] FIG. 7 shows a scientific diagram of an XPS (X-ray photoelectron spectroscopy) measurement of three intensity spectra. The upper intensity spectrum shows the existence of carbon as well as oxygen of the silicon dioxide. In a first trial, attempts were made to remove the carbon using pure argon. After ion bombardment with pure argon, the second intensity profile (in the middle) was recorded. In the second intensity profile, an increase in the carbon concentration is distinctly discernable. The increase in carbon concentration can have many causes. It is nevertheless important that the carbon comes from the process chamber 8. It has either accumulated there, has deposited on the walls, was introduced via parts of the ion sputtering system, or was introduced through the gate. Only a processing according to the invention of the substrate surface 7o by using the technique according to the invention in conjunction with the forming gas according to the invention yields a substrate surface that has been rid of carbon, as is visible in the third (the lower) intensity profile from the absence of the carbon profile at the same wavelength.
[0127] Analogous considerations apply to the trials carried out on Zerodur according to FIG. 8.
[0128] FIG. 9, in conclusion, shows the removal of carbon on a gold surface. This shows that the system and method according to the invention are also optimally suited for cleaning metal surfaces. With special preference, the method according to the invention can also be used to clean metal surfaces like copper in order to bond these in a further process step.
REFERENCE SIGN LIST
[0129] 1 Ion sputtering system [0130] 2, 2, 2 Ion source [0131] 3, 3, 3 Ion beam [0132] 4 Table [0133] 5 Substrate sample holder [0134] 6 Valve [0135] 7 Substrate [0136] 7o Substrate surface [0137] 8 Process chamber [0138] 9 Gate [0139] 10 Aperture
