WO2013026710A1

WO2013026710A1 - Device for the surface treatment of substrates

Info

Publication number: WO2013026710A1
Application number: PCT/EP2012/065602
Authority: WO
Inventors: Woo-Hong JUNG; Helge Haverkamp; Kai WEISSER; Michael Niethammer
Original assignee: Gebr.Schmid Gmbh
Priority date: 2011-08-22
Filing date: 2012-08-09
Publication date: 2013-02-28
Also published as: DE102011081327A1; CN103889588A; CN103889588B; TW201323094A

Abstract

A device for treating the undersides of wafers has transporting rollers (16a, 16b) for transporting the wafers, which at the same time are formed as conveying means for wetting the undersides of the wafers with liquid process medium (18). The transporting rollers are at least partially immersed in process medium for wetting the undersides of the wafers during transport when they are in contact with the transporting rollers. The transporting rollers have a rotationally symmetrical outer side, having a number of regions of a first, larger diameter (21) and a number of regions of a second, smaller diameter (25) in between, wherein channels are incorporated in the regions with the second, smaller diameter.

Description

Device for surface treatment of substrates

The invention relates to a device for surface treatment of substrates, in particular for wetting a substrate underside with a liquid process medium by transport rollers.

From EP 1 960 1 19 B1 a corresponding device is known. Here, the transport rollers are provided with raised end portions or end portions with a first larger diameter. On these end regions, the substrates to be treated are provided with a substrate underside. Because the transport rollers rotate with their lower regions in the process medium and thus their surface is wetted with process medium, due to the elevated end regions on which the substrates rest alone, only in these regions the substrate underside is wetted with process medium and thus treated. A full-surface treatment of the substrate base or its wetting should and is therefore not achieved with this device.

The invention is based on the object to provide an aforementioned device, can be solved with the problems of the prior art and in particular a good and, if necessary, full surface treatment of substrates or their substrate bases is possible. This object is achieved by a device having the features of claim 1. Advantageous and preferred embodiments of the invention are the subject of the other claims and are explained in more detail below. The wording of the claims is incorporated herein by express reference.

It is provided that the device has transport means for transporting a substrate in a transport plane determined by them, wherein these transport means are designed as transport rollers and at the same time as conveying means in order to wet or coat the substrate on a substrate underside with a liquid process medium and thus treat it. In this case, the transport rollers are at least partially immersed in the process medium or have process medium on their upper side. This allows them to wet the underside of the substrate during transport in direct contact.

According to the invention, the transport rollers have a rotationally symmetrical outer surface with a plurality of regions of a first, larger diameter and a plurality of regions of a second, smaller diameter, these regions of the second, smaller diameter each lying between two regions of the first, larger diameter. At least in the areas with the second, smaller diameter grooves or recesses are introduced, which are circumferentially and thus in turn rotationally symmetrical. In these grooves or depressions, a capillary action can be created or improved in order to build up a certain thickness of the film with process medium on the transport rollers. Thus, the underside of the substrate can be wetted in all cases over the entire surface or completely. By the grooves or depressions as well as by the areas of the first, larger diameter, which advantageously only slightly beyond the regions of the second, smaller diameter and on which the substrates rest, can be avoided that process medium is squeezed back on the transport rollers, so to speak and could then spill over onto the substrate top side at an edge or end edge of a substrate, which is undesirable, for example, in the case of an etching process with a corrosive process medium. In a further embodiment of the subject invention, the areas of the first, larger diameter may have a regular distance from each other. This can also be detached from the areas of the second, smaller diameter. A distance of the regions of the first, larger diameter may be about 10mm to 20mm, preferably 13mm to 17mm. In a further embodiment of the invention, the first, larger diameter can be less than 1 mm above the second, smaller diameter. Advantageously, the diameter difference is even less than 0.5 mm, particularly advantageously it is between 0.1 mm and 0.2 mm. The areas of the first, larger diameter are therefore only slightly above the areas of the second, smaller diameter lying in between. Thus, the substrates lie with their substrate undersides only on these areas of the first, larger diameter, on the other hand, the process medium just taken from the surface of the areas of the second, smaller diameter from the bath to the substrate bottom for the purpose of wetting the same or promoted and so desired full-surface wetting of the substrate underside can be effected. At the same time, the aforementioned squeezing of the film of process medium at the underside of the substrate can be avoided by the slightly greater distance between the underside of the substrate and the areas of the second, smaller diameter. In the areas of the first, larger diameter, it can easily be avoided that they are relatively narrow.

In a further embodiment of the invention, the regions of the first, larger diameter can have a transition to the regions with the second, smaller diameter, which is bevelled. Such a bevel angle can be between 45 ° and 60 °. On the one hand, this improves the above-mentioned prevention of squeezing or sloshing back of the film from process medium. Furthermore, by means of a chamfer, the adhesion of the process medium or the wetting of the underside of the substrate can also be improved here. It is advantageously provided that the regions with the first, larger diameter are formed without grooves or depressions. Particularly advantageously, these areas of the first, larger diameter are relatively narrow, so that anyway there is hardly any space or necessity for such grooves or depressions. They may, for example, have a width of less than 1 mm, advantageously between 0.1 mm and 0.4 mm.

In a further embodiment of the invention, the grooves or recesses in the regions with the second, smaller diameter can be approximately V-shaped. A V-angle can be between 40 ° and 70 °, particularly advantageously between 50 ° to 60 °. This results in a relatively large opening angle of the grooves or depressions in the regions with the second, smaller diameter, which in turn is advantageous for the adhesion of process medium to the surface of the transport rollers in this area and thus enables better wetting of the substrate underside.

In an advantageous embodiment of the invention, the grooves or depressions are not particularly deep. Their depth can be between 0.1 mm and 1 mm, preferably about 0.5 mm. If this is added to the abovementioned height of the regions of the first, larger diameter of less than 1 mm, then it is quite obvious that overall good wetting of the substrate undersides with process medium can take place from the immersed surface of the transport rollers. In an advantageous embodiment of the invention, in the regions with the second, smaller diameter, a width between the individual grooves or depressions may be less than 1 mm. It can be particularly advantageous about 0.1 mm to 0.4 mm.

In a further development of the invention, in the areas with the second, smaller diameter, a greatest width of the grooves or depressions less than 1 mm, advantageously about 0.2 mm to 0.6 mm. This means that in the areas with the second, smaller diameter, the grooves can be wider than their spacing. In an advantageous embodiment of the invention, all grooves or depressions in the areas with the second, smaller diameter in a single transport roller may be the same in terms of depth and / or shape or profile. This can also apply to the shape or profile shape of the regions of the first, larger diameter.

Advantageously, in a rear region of the device along the transport path of the substrates in the transport plane similarly shaped transport rollers as the front, but which have a slightly greater depth of the grooves or depressions in the areas with second, smaller diameter than in the front of the Contraption. This depth may be about 30% to 60% larger, which allows the substrate bottoms to be wetted with less process media at the rear of the device. Thus, the amount of process medium introduced at the rear of the device can be reduced somewhat for a more homogeneous wetting or etching result.

In a further embodiment of the invention, the transport rollers may have a first, larger diameter of a few cm, advantageously 1 cm to 5cm, more preferably 1, 5cm to 2cm.

In yet another advantageous embodiment of the invention, the transport rollers are made of plastic, with PP or PVDF offer. Particularly advantageously, the transport rollers are integrally or in one piece and formed out of a single piece of material or formed as a one-piece piece of material, preferably made of relatively hard material with a closed surface. In a device described in this way, multicrystalline wafers can be etched or textured particularly advantageously. For monocrystalline wafers, a so-called pyramid texturing can be performed.

These and other features will become apparent from the claims, also from the description and the drawings, wherein the individual features in each case alone or more in the form of sub-combinations in an embodiment of the invention and in other areas be realized and advantageous areas represent protectable versions for which protection is claimed here. The subdivision of the application into individual sections and subheadings does not restrict the general validity of the statements made thereunder.

Embodiments of the invention are shown schematically in the drawings and are explained in more detail below. In the drawings: FIG. 1 shows a side view of a device according to the invention

Transport rollers that transport substrates in a transport plane and are partially submerged in process medium, Fig. 2 is an enlarged view of a single transport roller for

Details of their surface design with two areas of different diameters and

Fig. 3 is a high magnification of a section of Fig. 2 for the purpose of illustrating possible dimensions.

In Fig. 1 from the side in a very schematic representation of an inventive system or device 1 1 is shown, are transported and treated with the substrates 12. In this case, the substrates 12 with an upper side 13 upwards and a lower side 14 downwards, wherein these are not necessarily the corresponding sides in the finished functional state, but relate only to this transport plane. The device 1 1 has transport rollers 16a and 16b, which are arranged in a known manner one behind the other, advantageously according to the aforementioned EP 1 960 1 19 B1. They rotate in the same direction and form with their tops the transport plane, wherein the substrates 12 rest with their lower sides 14 on the transport rollers 16a and 16b.

The lower portion of the transport rollers 16a and 16b is immersed in a bath of the process medium 18 in a trough not shown here or rotates therein. As a result, a film 19 of process medium 18 is taken along by the transport rollers 16a and 16b and brought upwards by the transport rollers 16a and 16b. This process is also known from the cited EP 1 960 1 19 B1, to which reference is made in this regard.

In the plan view of FIG. 2, the formation of a surface of a transport roller 16a is shown in a certain profile with relatively narrow first regions 21 of a first, larger diameter and relatively wide second regions 25 of a second, smaller diameter. The first regions 21 are respectively arranged at the ends of the transport roller 16a and have between them the second regions 25. A first region 21 is formed with a central elevation 22 as a kind of running surface or bearing surface for the substrates 12, wherein bevels 23a and 23b are located on the left and right of it. Although elevations 26 are likewise provided in the second regions 25, they do not extend to the elevations 22 of the first regions 21. The ridges 26 in the second regions 25 become formed by second bevels 27a and 27b, which are provided as a kind of cuts and grooves 29 form. From Fig. 2 it can be seen that the entire transport roller 16a is formed regularly. This means that the first regions 21 and their elevations 22 each have a constant distance from each other, which may be about 10mm to 20mm as described above. The entire width of a transport roller 16a may be a few cm, for example 5cm to 15cm. Their diameter according to Fig. 1 can be in the range of 1 cm to 3cm.

In the illustrated example, the second regions 25 each have eight elevations 26. There may also be more or fewer increases per se. Furthermore, not all second regions 25 must each have the same number of elevations 26.

From the high magnification in Fig. 3, once again the formation of the profile of the transport roller 16a becomes clear. The dimension bi for the width of the elevation 22 of the first region 21 may be between 0.2 mm and 0.6 mm. Advantageously, it also corresponds to the dimension b _{2 of} the width of the elevations 26 of the second region 25.

The dimension h as half the diameter difference or height difference between the elevations 22 and 26 may be in a range between slightly less than 0.1 mm and 0.5 mm, advantageously between 0.1 mm and 0.2 mm. The depth of the grooves 29 formed by the bevels 27a and 27b is then slightly above and can be 0.2mm to 0.4mm. A width v of the grooves 29 is in the range of their depth and thus also at 0.2mm to 0.4mm. An angle α of the grooves 29 may be in an aforementioned range, advantageously 50 ° to 60 °. The grooves 29 need not be formed at an acute angle in the lower region, but may also be slightly rounded, for example, for ease of manufacture. The bevel angle of the Ridges 22 of the first regions 21 to the lateral first slopes 23a and 23b may be the same as from the ridges 26 of the second regions 25 to the lateral second slopes 27a and 27b.

It can also be seen from FIG. 2 that the substrate 12, with its lower side 14, rests on the elevations 22 of the first regions 21 and has a film 19 of process medium 18 toward the second regions 25, which then precisely measures the film thickness with the dimension h corresponding to FIG. 3 or additionally a film thickness in the grooves 29 inside. As can be seen, therefore, the second regions 25 of smaller diameter function as conveyor regions, i. as areas in which process medium 18 is taken from the bath as said process medium film 19 to the substrate base 14 or promoted. By varying the dimension h and the depth of the grooves 29, the amount of process medium 18 brought to the substrate bottom 14 can be varied. For this reason, it is also appropriate, in the case of the device 11 according to FIG. 1, for the transport rollers 16b, to choose this measure of the height difference h to be slightly lower, for example 20% to 40%. Here in the rear part of the device 11, a smaller amount of process medium 18 fed to the underside 14 is considered sufficient. Here, the grooves 29 can be deeper. By means of deeper grooves 29 having a greater width, a smaller amount of process medium 18 is brought to the underside 14 of the substrates 12.

Said relatively small distance between the elevations 22 of the first regions 21, on which the substrate 12 rests, can prevent sagging of these resting substrates 12. This also applies to very small substrate thicknesses for the production of solar cells of less than 0.2 mm with increasing tendency towards 0.1 mm. The edges of the substrates 12 parallel to the transport direction are not contacted or touched with a correspondingly clever placement of the transport rollers 16a and 16b. The adhesion forces between the substrate 12 on the one hand and the liquid film 19 or process medium 18 on the other hand and the surface tension of the process medium 18 are used to completely wet the substrate on its underside. In Fig. 2 left a kind of concave meniscus on the process medium 18 can be seen. Precisely the concave formation prevents the process medium 18 from spilling over onto the upper side 13 of the substrate 12. It can also be seen from the representation in FIG. 2 that spilling over of back-squeezed process medium onto the upper side 13 of the substrates 12 is avoided if these should not be treated. So there are no problems with envelope odgl ..

The device 1 shown with the novel transport rollers 16a and 16b is particularly suitable for edge insulation of wafers for solar cell production, wherein the process medium HN ₃ 0 and HF has. Further process parameters are transport speed or rotational speed of the transport rollers 16a and 16b, temperature, immersion depth of the transport rollers 16a and 16b into the process medium 18, possible suction between the transport rollers and composition of the process medium per se.

Claims

claims

Device for the surface treatment of substrates, with transport means (16a, 16b) for transporting a substrate in a transport plane determined by the transport means, wherein the transport means are designed as transport rollers and simultaneously as conveying means for wetting the substrate with a liquid process medium (18) on one Substrate base, wherein the transport rollers are at least partially submerged in process medium or process medium at its top for wetting the substrate base during transport in direct contact between transport and substrate surface, characterized in that the transport rollers have a rotationally symmetrical Au ßenseite with several areas (21) of a first, larger diameter and a plurality of areas (25) of a second, smaller diameter therebetween, wherein at least in the areas with the second, smaller diameter grooves or recesses (29) are introduced.

Apparatus according to claim 1, characterized in that at least the areas of the second, smaller diameter are designed as process medium conveying areas through which the process medium from a process medium bath, in which the transport rollers are immersed at least with a lower portion, is conveyed to the substrate bottom.

Device according to claim 1 or 2, characterized in that the regions of the first, larger diameter have a regular distance from one another and / or the regions of the second, smaller diameter have a regular distance from one another and / or the distance between the regions of the first, larger diameter is about 10mm to 20mm, preferably 13mm to 17mm.

4. Device according to one of the preceding claims, characterized in that the first, larger diameter by less than 1 mm larger than the second, smaller diameter, in particular by less than 0.5 mm or between 0.1 mm and 0.2 mm.

5. Device according to one of the preceding claims, characterized in that the areas of the first, larger diameter are bevelled in the transition to the areas with the second, smaller diameter, in particular at an angle between 45 ° and 60 °.

6. Device according to one of the preceding claims, characterized in that the areas are formed with the first, larger diameter without grooves or depressions.

7. Device according to one of the preceding claims, characterized in that the grooves or depressions in the areas with the second, smaller diameter are V-shaped, in particular with an angle between 40 ° and 70 ° or between 50 ° to 60 ° ,

8. Device according to one of the preceding claims, characterized in that the grooves or depressions have a depth between 0.2 mm and 1 mm, in particular about 0.5 mm.

9. Device according to one of the preceding claims, characterized in that in the areas with the second, small ren diameter is the width between the grooves or recesses less than 1 mm, preferably 0.1 mm to 0.4 mm.

10. Device according to one of the preceding claims, characterized in that in the areas with the second, smaller diameter, the largest width of the grooves or depressions is less than 1 mm, preferably 0.2 mm to 0.6 mm.

1 1. Device according to one of the preceding claims, characterized in that all grooves or depressions in the

Regions with the second, smaller diameter at a transport roller are formed equal in depth and shape, preferably in a rear region of the device, the transport rollers have a greater depth of the grooves or depressions than in the front region, in particular an approximately

30% to 60% greater depth.

12. Device according to one of the preceding claims, characterized in that at the ends of the transport rollers areas with the first, larger diameter are provided and in between further areas with this first, larger diameter.