METHOD AND DEVICE FOR TREATING THE UNDERSIDE OF A SUBSTRATE

Abstract

A method for treating the underside of a planar substrate with a treatment medium includes hydrophobizing the underside of the substrate, subsequently forming a protective liquid film on a top side of the substrate and then bringing the treatment medium into contact with the underside of the substrate. In the process, the protective liquid film protects the upper side of the substrate from any action or effect of the treatment medium and/or outgassing. A device for carrying out the method is also provided.

Claims

1-19. (canceled)

20. A method for treating an underside of a planar substrate with a treatment medium, the method comprising the following steps: hydrophobizing the underside of the substrate; subsequently forming a protective liquid film on a top side of the substrate; and subsequently bringing the treatment medium into contact with the underside of the substrate while using the protective liquid film to protect the top side of the substrate from at least one of action or outgassing of the treatment medium.

21. The method according to claim 20, which further comprises: providing a silicon substrate as the substrate to be treated; and carrying out the step of hydrophobizing the underside of the silicon substrate by removing a silicate glass layer from the underside of the silicon substrate.

22. The method according to claim 20, which further comprises: carrying out the step of forming the protective liquid film by dipping the substrate into a protective liquid and removing the substrate from the protective liquid; and orienting the substrate to extend in a substantially horizontally extending plane upon removing the substrate from the protective liquid, causing the protective liquid film to remain on the top side of the substrate.

23. The method according to claim 20, which further comprises before carrying out the step of forming the protective liquid film, hydrophobizing edges of the substrate together with or separately from the step of hydrophobizing the underside of the substrate.

24. The method according to claim 20, which further comprises carrying out the step of hydrophobizing the underside of the substrate by using one-sided, wet-chemical etching.

25. The method according to claim 24, which further comprises carrying out the step of hydrophobizing the underside of the substrate by wetting the substrate from below with an etching liquid.

26. The method according to claim 24, which further comprises: after carrying out the step of hydrophobizing the underside of the substrate by wet-chemical etching, applying a rinsing liquid to the substrate for rinsing; choosing a quantity of the rinsing liquid applied to the substrate to cause at least half of the applied quantity of rinsing liquid to drip off the substrate; and using rinsing liquid remaining on the top side of the substrate as the protective liquid film.

27. The method according to claim 22, which further comprises: carrying out the step of hydrophobizing the underside of the substrate by using one-sided, wet-chemical etching; and subsequently dipping the substrate into a rinsing liquid for rinsing and simultaneously using the rinsing liquid as the protective liquid, causing removal of the substrate from the rinsing liquid to simultaneously represent the removal of the substrate from the protective liquid.

28. The method according to claim 26, which further comprises using water as the rinsing liquid.

29. The method according to claim 26, which further comprises using deionized water as the rinsing liquid.

30. The method according to claim 20, which further comprises using an etching medium as the treatment medium, and etching the underside of the substrate by using the etching medium.

31. The method according to claim 20, which further comprises carrying out the step of forming the protective liquid film by applying the protective liquid to the top side of the substrate a multiplicity of times.

32. A device for treating undersides of planar substrates with a treatment medium, the device comprising: a preconditioning tank containing a liquid for hydrophobizing the undersides of the substrates to be treated; a rinsing tank disposed downstream of said preconditioning tank in a transporting direction of the substrates for forming a protective liquid film on top sides of the substrates; a treatment tank disposed downstream of said rinsing tank in said transporting direction of the substrates, said treatment tank containing a treatment liquid to be brought into contact with the undersides of the substrates while protecting the top sides of the substrates from at least one of action or outgassing of said treatment medium; and transporting rollers disposed in said preconditioning tank for transporting the substrates through said preconditioning tank, a majority or all of said transporting rollers being plateau-free structure rollers.

33. The device according to claim 32, which further comprises: transporting rollers disposed in said rinsing tank for transporting the substrates through said rinsing tank, a majority or all of said transporting rollers being O-ring rollers; said O-ring rollers each having a shaft element with a longitudinal direction and a plurality of O-ring receptacles spaced apart from one another in said longitudinal direction; and said O-ring rollers having O-rings each being disposed in a respective one of said O-ring receptacles, and said O-rings each circumferentially surrounding one of said shaft elements and a respective one of said O-ring receptacles.

34. The device according to claim 32, which further comprises transporting rollers disposed in said treatment tank for transporting the substrates through said treatment tank, a majority or all of said transporting rollers being plateau-free structure rollers.

35. The device according to claim 32, wherein: said liquid for hydrophobizing the undersides of the substrates is an etching solution containing hydrofluoric acid; and said treatment liquid is a further etching solution containing hydrofluoric acid and an oxidizing agent.

36. The device according to claim 35, wherein said oxidizing agent is nitric acid or hydrogen peroxide.

37. The device according to claim 32, which further comprises a plurality of application devices for applying a protective liquid to the top sides of the substrates, said plurality of application devices being mutually offset in said transporting direction of the substrates.

38. The device according to claim 37, wherein at least one of said plurality of application devices is disposed above said rinsing tank.

39. The device according to claim 38, wherein at least one of said plurality of application devices is disposed downstream of said rinsing tank in said transporting direction of the substrates.

40. The device according to claim 39, wherein at least one of said plurality of application devices is disposed above said treatment tank.

Description

[0039] The invention is explained in more detail in the following text with reference to figures. Where expedient, elements with the same action are provided with the same reference signs therein. The invention is not limited to the exemplary embodiments illustrated in the figures—not even with regard to functional features. The above description and the following description of the figures contain numerous features which are reproduced in the dependent claims, in some cases combined into groups. However, a person skilled in the art will also consider these features and also all of the other features disclosed above and in the following description of the figures individually and combine them into appropriate further combinations. In particular, these features are each able to be combined individually and in any desired suitable combination with the method and/or the device of the independent claims. In the figures:

[0040] FIG. 1 shows a first exemplary embodiment of the method according to the invention and of the device according to the invention in a schematic illustration

[0041] FIG. 2 shows a side view of a plateau-free structure roller from FIG. 1

[0042] FIG. 3 shows a detail illustration of a subregion A from FIG. 2

[0043] FIG. 4 shows a schematic illustration of an O-ring roller

[0044] FIG. 5 shows a second exemplary embodiment of the method according to the invention and of the device according to the invention in a schematic illustration

[0045] FIG. 6 shows a third exemplary embodiment of the method according to the invention and of the device according to the invention in a schematic illustration.

[0046] FIG. 1 illustrates a schematic illustration of an exemplary embodiment of the method according to the invention and of the device according to the invention. In this exemplary embodiment, a silicon substrate 10, which is provided on its entire surface with a phosphorus silicate glass layer 12, for example as a result of phosphorus diffusion, is transported in a transporting direction 16 through a succession of different tanks by means of transporting rollers. First of all, an underside 14 and the edges 13 of the substrate 10 are hydrophobized in a preconditioning tank 50. For this purpose, the underside 14 of the substrate 10 is wetted from beneath with a hydrophobizing liquid 52, in the present exemplary embodiment with an etching solution containing hydrofluoric acid. Exclusively plateau-free structure rollers 54 are provided as transporting rollers in the preconditioning tank, said plateau-free structure rollers 54 allowing homogeneous etching. As a result, the phosphorus silicate glass layer 12 is removed uniformly from the underside 14 and from the edges 13.

[0047] A side view of the plateau-free structure rollers 54 used in the exemplary embodiment in FIG. 1 can be found in FIG. 2. An enlarged illustration of the subregion A is reproduced in FIG. 3. In the latter, deeply grooved recesses 80 are discernible, which are arranged on the structure roller 54 in a manner immediately adjoining one another and form raised regions. Walls 82 of two adjacent recesses 80 are in this case arranged in a manner closely adjoining one another such that these raised regions do not exhibit a plateau but rather the shape of a point 55. As explained above, the plateau-free structure rollers 54 allow homogeneous etching of the underside 14 of the substrate 10 in the preconditioning tank 50 with a comparatively low risk of undesired local hydrophobizing of the top side 15 as a result of hydrophobizing liquid 52 being scooped onto the top side 15.

[0048] In the further procedure, the substrate 10 is transported into a rinsing tank 58 which contains deionized water 60 as rinsing medium. There, it is dipped into the deionized water 60 that serves as rinsing liquid. In this case, the deionized water 60 is simultaneously used as protective liquid. The substrate 10 is transported in the rinsing tank 58 by means of O-ring rollers 56 which minimize the bearing surface for the substrate and in this way allow an efficient rinsing operation. Water 62 overflowing out of the rinsing tank 58 is collected in an overflow tank 64.

[0049] FIG. 4 shows a schematic illustration of a portion of the O-ring roller 56. The O-ring roller 56 has a shaft element 72 and O-ring receptacles which are spaced apart from one another in the longitudinal direction of the shaft element 72 and are embodied as recesses 74 in the shaft element 72 in the case of the present example, an O-ring 76 being arranged in each of said recesses 74. The portion of the O-ring roller 56 that is illustrated in FIG. 4 has two O-rings 76. This number is sufficient in principle for transporting the planar substrate 10. If necessary, for example in the case of larger or fragile substrates, a larger number of O-rings can be provided.

[0050] If the substrate 10 is transported onward in the transporting direction 16 by means of the O-ring shafts 56, it is removed from the rinsing tank 58 in this way. In this case, the substrate 10 extends in a horizontally extending plane. The O-ring rollers 56 are oriented in a corresponding manner for this purpose. The previously hydrophobized edges 13 and the hydrophobized underside 14 are free of deionized water 60 after the substrate 10 has been removed from the rinsing tank 58. By contrast, a protective liquid film 66 of deionized water 60 remains on the top side 15. The hydrophilic phosphorus silicate glass layer 12 that remains on the top side 15 of the substrate 10 additionally favors the formation of the protective liquid film 66, wherein hydrophilicity should be understood in the present sense as meaning a contact angle between the surface and wetting liquid of less than 15°. The hydrophilicity of the top side 15 also additionally counteracts any running off of deionized water from the protective liquid film 66.

[0051] Subsequently, the substrate 10 is transported into a treatment tank 60 which contains an etching solution 70. In the present exemplary embodiment, an etching solution 70 containing hydrofluoric acid and nitric acid is provided as the etching solution. Alternatively, it is possible, inter alia, to use an etching solution which contains sulfuric acid in addition to hydrofluoric acid and nitric acid. While the substrate is transported through the treatment tank 68 by means of the plateau-free structure rollers 54, the etching solution 70 is brought into contact with and etches the underside 14 of the substrate. The top side 15 of the substrate 10 is, by contrast, protected by the protective liquid film 66 against etching solution 70 passing onto the top side 15 and against any effect of outgassings from the etching solution 70, in particular from etching vapors. The underside 14 is etched without the sensitive top side 15 of the substrate 10 being impaired. Any running off of deionized water from the protective liquid film 66 or creeping of etching solution 70 onto the top side 15 of the substrate 10 is prevented. No streaking occurs on the underside 14 of the substrate 10 and the etching solution 70 is not contaminated or diluted by parts of the protective liquid film 66 running off the top side 15 of the substrate 10. The above-described advantages of the plateau-free structure rollers 54 also have a positive effect in the treatment tank, and so the risk of damage to the top side 15 of the substrate 10 is further reduced by the exclusive use of plateau-free structure rollers 54.

[0052] A residence time of the substrates 10 in the preconditioning tank 50 should be chosen such that the phosphorus silicate glass layer 12 is reliably removed from the underside 14 of the substrate 10. The length of the preconditioning tank 50 should optionally be adapted in a corresponding manner. However, the substrates cannot be exposed to the hydrophobizing liquid 52 for any desired length of time. Otherwise, it is possible for the hydrophobizing liquid 52 to creep onto the top side 15 of the substrate 10 and to considerably damage the latter or layers located therebeneath. The residence time of the substrates in the preconditioning tank 50, and the length of this tank, should therefore be chosen accordingly. Otherwise, depending on the thickness of the phosphorus silicate glass layer 12 or depending on material properties and thicknesses of other layers to be removed, it may be advantageous to use suitable transporting rollers. For example, plateau-free structure rollers that are grooved more or less deeply can be used.

[0053] FIG. 5 illustrates a schematic illustration of a second exemplary embodiment of the method according to the invention and of the device according to the invention. This differs from the first exemplary embodiment in FIG. 1 in that, instead of the rinsing tank 58, a rinsing tank 158 is provided which collects rinsing liquid. For the purposes of rinsing, a surge pipe 160 is provided, by means of which the deionized water 60 used as rinsing liquid is applied to the top side 15 of the silicon substrates. The deionized water 60 is applied in such a quantity that water 162 that drips off over the edges 13 of the silicon substrates 10 rinses the silicon substrates. Once the silicon substrate 10 has passed through under the surge pipe 160, a film of deionized water remains on the top side 15 of the silicon substrates 10, said film being used as protective liquid film 66. If it is not necessary to rinse the substrates, the deionized water, or some other suitable protective liquid, can in principle be applied in a metered manner to the top side 15 of the silicon substrates 10 by means of the surge pipe 160 such that the protective liquid film 66 is formed but only as little protective liquid as possible runs over the edges 13 of the silicon substrates 10 and drips into the rinsing tank 158.

[0054] FIG. 6 illustrates a schematic illustration of a third exemplary embodiment of the method according to the invention and of the device according to the invention. This differs from the second exemplary embodiment illustrated in FIG. 5, inter alia, in that, in addition to a surge pipe 160a, a further surge pipe 160b is provided, which is arranged downstream of the surge pipe 160a in the transporting direction 16 of the substrates 10. By means of these surge pipes 160a and 160b, the deionized water 60 is again applied as protective liquid to the substrates 10. The surge pipes 160a, 160b thus serve as application devices. Since they are arranged in an offset manner with respect to one another in the transporting direction 16 of the substrates, the deionized water 60 is applied as protective liquid several times to the top side 15 of the substrates 10 by means of these surge pipes 160a, 160b.

[0055] The deionized water 60 applied to the top side 15 of the substrates 10 by means of the surge pipe 160a forms a protective liquid film 66a which, in the particular application case, possibly does not yet completely cover the top side 15 or does not yet have a sufficient thickness. In particular, the protective liquid film 66a can have formed islands such that parts of the top side 15 are not or not sufficiently covered with protective liquid. As a result of the second application of deionized water 60 as protective liquid by means of the surge pipe 160b, imperfections in the protective liquid film 66a can be compensated, such that a protective liquid film 66b completely covering the top side 15 of the substrates 10 is present. If the protective liquid film 66a merely does not have a sufficient thickness, the application of the deionized water 60 by means of the surge pipe 160b brings about a thicker protective liquid film 66b.

[0056] As described above, as a result of the protective liquid, in the present case the deionized water 60, being applied several times, a better distribution of the protective liquid in corners of the substrates 10 and the peripheries of the substrates 10 can be brought about. After the rinsing tank 158 has been passed through, in the exemplary embodiment in FIG. 6, a protective liquid film 66c is thus present which completely and homogeneously covers the top side 15 of the substrates 10. Depending on the application case, the application of deionized water 60, or of protective liquid, several times can reduce the total quantity of overflowing water 162. This allows a reduction in the procedural effort, in particular when protective liquids other than water are used.

[0057] In the exemplary embodiment in FIG. 6, a further surge pipe 160c for applying the deionized water 60 to the top side 15 of the substrates 10 is arranged above the treatment tank 68, and thus downstream of the rinsing tank 158 in the transporting direction 16 of the substrates 10. The surge pipe 160c is, like the surge pipes 160a and 160b, provided to apply deionized water 60 as protective liquid to the top side 15 of the substrates 10. In this way, losses of deionized water 60 which the protective liquid film 66c has suffered on the way to the treatment tank 68, for example on account of evaporation, can be compensated, and so the top side 15 of the substrates 10 is protected from any action of the treatment medium 70 and/or outgassings thereof via the treatment tank 68 by means of an ideal protective liquid film 66d.

[0058] In the exemplary embodiment in FIG. 6, three application devices for protective liquid are provided by the surge pipes 160a, 160b, 160c. Depending on the requirements of the individual application case, one of these application devices, preferably the surge pipe 160b or the surge pipe 160c, can be dispensed with. With the remaining two surge pipes, a plurality of application devices that are arranged in an offset manner with respect to one another in the transporting direction 16 of the substrates 10 are still present, said application devices allowing protective liquid, in the present case deionized water 60, to be applied several times for the purpose of forming the protective liquid film. In an application case in which the protective liquid can be applied in a metered manner such that, when protective liquid is applied to the top side 15 of the substrate via the treatment tank 68, virtually no protective liquid overflows and thus also does not pass into the etching solution 70, it has proven particularly advantageous to keep the surge pipe 160c, or more generally an application device above the treatment tank 68.

[0059] The concept, illustrated in the exemplary embodiment in FIG. 6, of a plurality of application devices arranged in an offset manner with respect to one another in the transporting direction 16 of the substrates 10 can be transferred readily to the exemplary embodiment in FIG. 1. For this purpose, one or more application devices would need to be provided downstream of the rinsing tank in the transporting direction 16 of the substrates in the exemplary embodiment in FIG. 1, by means of which application devices deionized water can again be applied as protective liquid to the top side 15 of the substrates. For example, the surge pipes 160b or 160c known from FIG. 6 or the like could be used. In particular, such a further application device could be arranged above the treatment tank 68 in FIG. 1.

[0060] The invention has been illustrated and described in more detail by way of the exemplary embodiments illustrated and explained. Nevertheless, the invention is not limited to or by the examples disclosed. Other variants can be derived from these exemplary embodiments by a person skilled in the art without deviating from the concept underlying the invention.

LIST OF REFERENCE SIGNS

[0061] 10 Silicon substrate

[0062] 12 Phosphorus silicate glass layer

[0063] 13 Edge

[0064] 14 Underside

[0065] 15 Top side

[0066] 16 Transporting direction

[0067] 50 Preconditioning tank

[0068] 52 Hydrophobizing liquid

[0069] 54 Structure roller

[0070] 55 Point

[0071] 56 O-ring roller

[0072] 58 Rinsing tank

[0073] 60 Deionized water

[0074] 62 Overflowing water

[0075] 64 Overflow tank

[0076] 66 Protective liquid film

[0077] 66a Protective liquid film

[0078] 66b Protective liquid film

[0079] 66c Protective liquid film

[0080] 66d Protective liquid film

[0081] 68 Treatment tank

[0082] 70 Etching solution

[0083] 72 Shaft element

[0084] 74 Recess

[0085] 76 O-ring

[0086] 80 Recess

[0087] 82 Wall

[0088] 158 Rinsing tank

[0089] 160 Surge pipe

[0090] 160a Surge pipe

[0091] 160b Surge pipe

[0092] 160c Surge pipe

[0093] 162 Overflowing water