Abstract
A method for the surface treatment of a substrate surface of a substrate includes arranging the substrate surface in a process chamber, bombarding 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, and introducing 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 includes 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, and means to introduce a second component into the process chamber to bind the removed impurities.
Claims
1. A 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 to remove impurities from the substrate surface, the ion beam having an ion energy <1000 eV and a first component, the ion beam being generated and aimed at the substrate surface by an ion beam source; and introducing a second component into the process chamber to bind the removed impurities, wherein a depth range of the substrate, within which a microstructural change due to the bombarding of the substrate is verifiable, is less than 10 ?m.
2. The method according to claim 1, wherein the depth range is less than 15 nm.
3. The method according to claim 1, wherein the depth range is less than 1.5 nm.
4. A device for the surface treatment of a substrate surface of a substrate, the device comprising: a process chamber in which the substrate is arranged; an ion beam source configured to generate an ion beam with an ion energy <1000 eV and aim the ion beam at the substrate surface, the ion beam being configured to bombard the substrate surface to remove impurities from the substrate surface such that a verifiable microstructural change to the substrate is limited to a depth range of less than 10 ?m, the ion beam having a first component; and means for introducing a second component into the process chamber to bind the removed impurities.
5. The device according to claim 4, wherein the depth range is less than 15 nm.
6. The device according to claim 4, wherein the depth range is less than 1.5 nm.
7. A device for the surface treatment of a substrate surface of a substrate, the device comprising: a process chamber in which the substrate is arranged; an ion beam source having an exit opening, the ion beam source configured to generate an ion beam with an ion energy <1000 eV and aim the ion beam at the substrate surface, the ion beam being configured to bombard the substrate surface to remove impurities from the substrate surface, the ion beam having a first component; and means for introducing a second component into the process chamber to bind the removed impurities, wherein a distance between the exit opening and the substrate is in a range of 1 cm to 100 cm.
8. The device according to claim 7, wherein the distance between the exit opening and the substrate is in a range of 10 cm to 80 cm.
9. The device according to claim 7, wherein the distance between the exit opening and the substrate is in a range of 20 cm to 50 cm.
10. The method according to claim 1, wherein a temperature of the process chamber is less than 100? C.
11. The method according to claim 1, wherein a temperature of the process chamber is at room temperature.
12. The device according to claim 4, wherein a temperature of the process chamber is less than 100? C.
13. The device according to claim 4, wherein a temperature of the process chamber is at room temperature.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0109] 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:
[0110] FIG. 1 shows a schematic depiction of a first embodiment according to the invention;
[0111] FIG. 2 shows a schematic depiction of a second embodiment according to the invention;
[0112] FIG. 3 shows a schematic depiction of a third embodiment according to the invention;
[0113] FIG. 4 shows a schematic depiction of a fourth embodiment according to the invention;
[0114] FIG. 5 shows a scientific diagram of the concentration dependence of multiple atoms on treatment time;
[0115] FIG. 6a shows a scientific diagram of the intensity dependence of an XPS signal on the wavelength for the material silicon;
[0116] FIG. 6b shows a microscopic surface image of a substrate surface before the treatment according to the invention;
[0117] FIG. 6c shows a microscopic surface image of a substrate surface after the treatment according to the invention;
[0118] FIG. 7 shows a scientific diagram of the intensity dependence of an XPS signal on the wavelength for the material silicon oxide;
[0119] FIG. 8 shows a scientific diagram of the intensity dependence of an XPS signal on the wavelength for the material Zerodur; and
[0120] FIG. 9 shows a scientific diagram of the intensity dependence of an XPS signal on the wavelength of the material gold.
[0121] In the figures, equal or effectively equal features are labelled with the same reference signs.
DETAILED DESCRIPTION OF THE INVENTION
[0122] 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.
[0123] The process gas is preferably the same forming gas that is used by the ion source 2 to generate the ion beam 3.
[0124] 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.
[0125] 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.
[0126] 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.
[0127] 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 and 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.
[0128] 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.
[0129] 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 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.
[0130] Analogous considerations apply to the trials carried out on Zerodur according to FIG. 8.
[0131] 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
[0132] 1 Ion sputtering system [0133] 2, 2, 2 Ion source [0134] 3, 3, 3 Ion beam [0135] 4 Table [0136] 5 Substrate sample holder [0137] 6 Valve [0138] 7 Substrate [0139] 7o Substrate surface [0140] 8 Process chamber [0141] 9 Gate [0142] 10 Aperture
