Method for applying a bonding layer

Abstract

A method for applying a bonding layer that is comprised of a basic layer and a protective layer on a substrate with the following method steps: application of an oxidizable basic material as a basic layer on a bonding side of the substrate, at least partial covering of the basic layer with a protective material that is at least partially dissolvable in the basic material as a protective layer. In addition, the invention relates to a corresponding substrate.

Claims

1. A method for bonding a first substrate with a second substrate, said method comprising: applying an oxidizable basic material as a basic layer on a bonding side of the first substrate, at least partially covering the basic layer with a protective layer having a thickness of less than 100 nm, the protective layer being comprised of a protective material, and bonding the first and second substrates, the bonding comprising at least partially dissolving the protective material in the basic material, the bonding being performed at a temperature that is less than a eutectic temperature of a eutectic system of the basic material and the protective material.

2. The method according to claim 1, wherein the basic material is oxygen-affine and is comprised of aluminum and/or copper.

3. The method according to claim 1, wherein the step of applying the basic material as the basic layer and/or covering the basic layer with the protective layer is/are carried out by deposition.

4. The method according to claim 1, wherein the protective layer is applied such that the basic layer is sealed at least predominantly relative to the atmosphere.

5. The method according to claim 1, wherein the protective layer is treated before the step of bonding, said protective layer treated with one or more of the following processes: (a) chemical oxide removal; (b) physical oxide removal, in particular with plasma; and (c) ion-assisted chemical etching.

6. The method according to claim 5, wherein said chemical oxide removal process includes a gaseous reducing agent and/or a liquid reducing agent.

7. The method according to claim 5, wherein said ion-assisted chemical etching process includes fast ion bombardment, grinding and/or polishing.

8. The method according to claim 1, wherein one or more of the following materials are selected as the basic material and/or the protective material: (a) metals; (b) alkali metals; (c) alkaline-earth metals; (d) alloys; and (e) semiconductors, provided with corresponding doping.

9. The method according to claim 8, wherein said metals are selected from the group consisting of: Cu, Ag, Au, Al, Fe, Ni, Co, Pt, W, Cr, Pb, Ti, Te, Sn, Zn, and Ga.

10. The method according to claim 8, wherein said alkali metals are selected from the group consisting of: Li, Na, K, Rb, and Cs.

11. The method according to claim 8, wherein said alkaline earth metals are selected from the group consisting of: Mg, Ca, Sr, and Ba.

12. The method according to claim 8, wherein said semiconductors are selected from the group consisting of: element semiconductors and compound conductors.

13. The method according to claim 12, wherein said element semiconductors are selected from the group consisting of: Si, Ge, Se, Te, B, and Sn.

14. The method according to claim 12, wherein said compound semiconductors are selected from the group consisting of: GaAs, GaN, InP, InxGal-xN, InSb, InAs, GaSb, AlN, InN, GaP, BeTe, ZnO, CuInGaSe.sub.2, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, Hg(1-x)Cd(x)Te, BeSe, HgS, AlxGal-xAs, GaS, GaSe, GaTe, InS, InSe, InTe, CuInSe.sub.2, CuInS.sub.2, CuInGaS.sub.2, SiC, and SiGe.

15. The method according to claim 1, wherein the basic material is Al and the protective material is selected from the group consisting of Ge, Ga, Zn, and Mg.

16. The method according to claim 1, wherein the basic material is Al and the protective material is Ge.

17. The method according to claim 1, wherein the bonding of the first and second substrates further comprises bringing the bonding side of the first substrate into contact with the second substrate.

18. The method according to claim 1, wherein the bonding of the first and second substrates comprises bringing the protective layer into contact with the second substrate.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 a depiction of the binary AlGe phase diagram,

(2) FIG. 2 a depiction of the binary AlGa phase diagram,

(3) FIG. 3 a depiction of the binary AlZn phase diagram,

(4) FIG. 4 a depiction of the binary AlMg phase diagram,

(5) FIG. 5a a diagrammatic cross-sectional depiction of an embodiment of a substrate according to the invention with a full-surface basic layer that consists of a basic material and a full-surface protective layer that consists of a protective material with alignment,

(6) FIG. 5b a diagrammatic cross-sectional depiction according to FIG. 5a with a contact/bonding step, and

(7) FIG. 5c a diagrammatic cross-sectional depiction according to FIG. 5a according to the bonding step.

DETAILED DESCRIPTION OF INVENTION

(8) FIG. 1 shows a first binary AlGe system by way of example. The important part in the phase diagram according to the invention is the mixed crystal area 7. The mixed crystal area 7 is separated from the two-phase areas 9, 10 by the boundary solubility 8. The boundary solubility for germanium decreases with decreasing temperature, starting from the eutectic temperature or the eutecticals 11. The boundary solubility for germanium also decreases with increasing temperature, starting from the eutectic temperature or the eutecticals 11.

(9) FIG. 2 shows a second binary AlGa system by way of example. The important part according to the invention in the phase diagram is the mixed crystal area 7. The mixed crystal area 7 is separated by the boundary solubility 8 from the two-phase areas 9, 10. The boundary solubility for gallium decreases with decreasing temperature, starting from the eutectic temperature or the eutecticals 11. The boundary solubility for gallium decreases also with increasing temperature, starting from the eutectic temperature or the eutecticals 11. The degradation of the eutectic by a eutectic point 6 that lies very near in the concentration of the pure germanium is characteristic.

(10) FIG. 3 shows a third binary AlZn system by way of example. The important part according to the invention in the phase diagram is the mixed crystal area 7. The mixed crystal area 7 is very pronounced here. At temperatures around 370 C., it reaches up to more than 65 mol % of zinc. The mixed crystal area 7 is separated by the boundary solubility 8 from the two-phase area 10. The boundary solubility for zinc decreases with decreasing temperature, starting from the eutectoid temperature or the eutectoids 11.

(11) FIG. 4 shows a fourth binary AlMg system by way of example. The important part according to the invention in the phase diagram is the mixed crystal area 7. The mixed crystal area 7 is separated by the boundary solubility 8 from the two-phase areas 9, 10. The boundary solubility for magnesium decreases with decreasing temperature, starting from the eutectic temperature or the eutecticals 11. The boundary solubility for magnesium also decreases with increasing temperature, starting from the eutectic temperature or the eutecticals 11.

(12) FIG. 5a shows as simple a system according to the invention as possible, comprised of a first substrate 4 and a second substrate 5. Both substrates 4 and 5 are coated with a basic material 1 and a protective material 2. In an embodiment according to the invention, basic material 1 and protective material 2 are not necessarily applied on the full surface on the first substrate 4 but rather have undergone a specific structuring before the bonding. In this step, possible oxide layers of the protective material 2 have already been removed.

(13) FIG. 5b shows a contact or bonding step of the two substrates 4 and 5. If the two substrates were structured, a previous orienting step would have had to have oriented the two substrates to one another before the actual contact or bonding step would take place.

(14) Finally, FIG. 5c shows the mixed crystal 12 that is produced and that is carried out by the diffusion of the protective layer material 2 into the basic material 1.

LIST OF REFERENCE SYMBOLS

(15) 1 Basic Material 2 Protective Material 3 Oxide Layer 4 First Substrate 5 Second Substrate 6 Eutectic Point 7 Mixed Crystal Area 8 Boundary Solubility 9 Two-Phase Area: Liquid, Solid 10 Two-Phase Area: Solid, Solid 11, 11 Eutecticals, Eutectoids 12 Mixed Crystal