Method for Creating Hydrophilic Surfaces or Surface Regions on a Substrate

Abstract

In a method for creating hydrophilic surfaces or surface regions on one or more silicon surfaces of a substrate, a vapour phase of hydrogen peroxide is generated in a reactor by heating an aqueous hydrogen peroxide solution. The substrate having the silicon surface or surfaces to be treated is exposed to the vapour phase, whereby a hydrophilisation of the silicon surfaces in achieved.

Claims

1. A method for creating hydrophilic surfaces or surface regions on one or more silicon surfaces of a substrate, comprising: heating an aqueous hydrogen peroxide solution so as to create a vapor phase of hydrogen peroxide in a reactor; and exposing the one or more silicon surfaces of the substrate to the vapor phase.

2. The method as claimed in claim 1, wherein the step of heating the aqueous hydrogen peroxide solution includes heating the aqueous hydrogen peroxide solution to a first temperature, the method further comprising: heating the substrate to a second temperature which is greater than the first temperature.

3. The method as claimed in claim 2, wherein the second temperature is greater than 1-10° C. in comparison to the first temperature.

4. The method as claimed in claim 2, wherein the second temperature is greater than 1-5° C. in comparison to the first temperature.

5. The method as claimed in claim 1, wherein the step of heating the aqueous hydrogen peroxide solution includes heating the aqueous hydrogen peroxide solution to 30-90° C.

6. The method as claimed in claim 1, wherein the step of heating the aqueous hydrogen peroxide solution includes heating the aqueous hydrogen peroxide solution to 40-60° C.

7. The method as claimed in claim 1, wherein the aqueous hydrogen peroxide solution is a 5-85% strength solution.

8. The method as claimed in claim 1, wherein the aqueous hydrogen peroxide solution is a 30% strength solution.

9. The method as claimed in claim 1, further comprising: prior to the exposing step, orienting the one or more silicon surfaces of the substrate so as to face downwards in the reactor.

10. The method as claimed in claim 1, wherein the exposing step includes exposing the one or more silicon surfaces of the substrate to the vapor phase for 5-20 minutes.

11. The method as claimed in claim 1, wherein the exposing step includes exposing the one or more silicon surfaces of the substrate to the vapor phase for 10 minutes.

12. The method as claimed in claim 1, wherein the substrate is a silicon microarray wafer with one or more trench cells.

13. The method as claimed in claim 1, wherein the substrate is a microfluidic device configured for lab-on-chip applications.

14. A substrate having the hydrophilic surface or surface regions produced according to the method as claimed in claim 1.

Description

[0017] In the drawings:

[0018] FIG. 1 shows a sectional representation through a reactor known per se which is suitable for carrying out the proposed method and

[0019] FIG. 2 shows a sectional representation of a further design of a cover for a reactor according to FIG. 1.

DESCRIPTION OF EXAMPLES

[0020] FIG. 1 shows in a sectional representation, a reactor in which an aqueous hydrogen peroxide solution 11 is introduced. The substrate 100 with the silicon surfaces to be treated is inserted in the cover 20 of the reactor. The aqueous hydrogen peroxide solution is located in a container 12 within the reactor, wherein the container 12 is surrounded by a heating jacket 13. The heating jacket allows heating of the aqueous hydrogen peroxide solution 11 by means of a heating medium (arrow 14) flowing through the heating jacket 13, for example water in a heating circuit. Of course other heating methods are also possible. By heating the container 12, a homogeneous vapor phase 15 of hydrogen peroxide is created within the container 12. The reactor 10 is sealed towards the outside by an insulation jacket 16 so that the temperature within the container 12 is kept constant. The cover 20 of the reactor 10 is furnished with seals 17 which are in particular resistant to the hydrogen peroxide vapor 15. A heating device 18 is located in the cover 20 so that the substrate 100 (silicon substrate) fixed on the inner side of the cover 20 may be heated to the required temperature.

[0021] FIG. 2 shows a further possible design of the cover 30 of the reactor 10. The substrate 100 is thus not arranged, for example clamped, headfirst as in FIG. 1 against an upper heating device 18, but placed on a heating plate located therebelow as heating device 19 which is connected to the upper part of the cover 30 via bars 21. The heating plate 19 is heated via heating devices 22.

[0022] The arrangement of the substrate 100 with the silicon surfaces to be treated may thus be arranged downwards with the aid of the cover 20 according to FIG. 1 in a particularly simple manner with orientation of the surfaces to be treated in the direction of the vapor phase 15 or with the surfaces to be treated, wherein the substrate 100 is clamped, for example by means of suitable clamps or the like. On the other hand, it is also possible to place the substrate 100 on a heating plate 19 of a cover 30 in the design according to FIG. 2 so that the surfaces of the substrate 100 to be treated are indeed orientated upwards, but nevertheless may be freely flooded by the vapor phase 15.

[0023] To actually carry out the method, the aqueous hydrogen peroxide solution 11 is heated, for example to a temperature between 30° C. and 90° C., preferably to a temperature between 40° C. to 60° C., for example to 45° C. A standardized 30% strength so-called “perhydrol” solution may be used with particular advantage as aqueous hydrogen peroxide solution. In the temperature range between 30° C. and 90° C., in particular between 40° C. and 60° C. and preferably at 45° C., the hydrogen peroxide solution has sufficient long-term stability and may be used without considerable change in concentration over a longer residence time in the reactor 10. Heating of the hydrogen peroxide solution 11 effects the creation of the vapor phase 15 from hydrogen peroxide and steam. Even before or also after creation of the vapor phase, the substrate 100 is placed in the reactor 10 either headfirst, for example according to the design of the cover 20 from FIG. 1 or with the surfaces to be treated upwards according to the design of cover 30 in FIG. 2 and brought to a temperature, which preferably lies above the temperature of the aqueous hydrogen peroxide solution, by means of the heating of cover 20 or 30. For example the substrate 100 is brought to a temperature which lies up to 10° C. above, in particular 1° C. to 5° C., and particularly preferably 3° C., above the temperature of the hydrogen peroxide solution 11. Hence, the silicon surfaces are exposed to the action of the hydrogen peroxide-steam mixture 15, thus oxidized and hydrophilized. Generally, a reaction period of 5 minutes to 20 minutes may be suitable for this. In particular a reaction period of 10 minutes is suitable, wherein after this reaction time, complete hydrophilization and purification of the silicon surfaces to be treated is usually already achieved.