PECVD BOAT

Abstract

A PECVD boat has at least one boat plate for accommodating wafers, for transport into and out of vacuum coating chambers. The boat plate is oriented vertically and has a plurality of U-shaped accommodating slots for accommodating wafers, which slots are oriented in the longitudinal direction of the boat plate and are open at the top, in such a way that the wafers inserted into the accommodating slots are aligned with the plate line of the boat plate.

Claims

1. A PECVD boat having at least one boat plate for receiving wafers, for transport into and out of vacuum coating chambers, wherein the boat plate is oriented vertically and has multiple U-shaped receiving slots oriented in a longitudinal direction of the boat plate and open at a top, for receiving wafers, such that the wafers inserted into the receiving slots are flush with a plate line of the boat plate.

2. The PECVD boat as claimed in claim 1, wherein each receiving slot is bounded by lateral retaining arms and a lower frame element of the boat plate, so that a wafer inserted into the receiving slot is partially surrounded by the lateral retaining arms.

3. The PECVD boat as claimed in claim 2, further including three receiving elements, wherein the lateral retaining arms and the lower frame element are each provided with one of the receiving elements, and the receiving elements are oriented inward into the receiving slot and grip around an outer edge of the inserted wafer in a U-shaped or fork-like manner and secure the wafer using just weight of the wafer.

4. The PECVD boat as claimed in claim 3, wherein the receiving elements of each receiving slot accommodates two wafers in back-to-back loading.

5. The PECVD boat as claimed in claim 1, including multiple boat plates arranged parallel, spaced apart from and next to one another, and connected to one another.

6. The PECVD boat as claimed in claim 5, further comprising spacing and connecting elements, made of a nonconductive material, located between the boat plates.

7. The PECVD boat as claimed in claim 6, wherein the spacing or connecting elements are made of Al.sub.2O.sub.3, quartz glass or ceramic.

8. The PECVD boat as claimed in claim 5, wherein the boat plates comprise shaped graphite, CFC or titanium.

Description

[0026] There follows a more detailed explanation of the invention by way of an exemplary embodiment. In the appended drawings:

[0027] FIG. 1 shows a boat plate according to the prior art for receiving wafers in the lying-down position;

[0028] FIG. 2 shows a boat plate according to the invention in an upright arrangement for receiving wafers;

[0029] FIG. 3 shows a PECVD boat consisting of multiple boat plates arranged parallel, spaced apart from and next to one another and connected to one another; and

[0030] FIG. 4 shows an enlarged view of a receiving element for wafers.

[0031] FIG. 2 shows a wafer holder 20 according to the invention, which in this case consists of a boat plate 21 which is oriented vertically or on edge and serves to receive multiple wafers 22. In the case shown, it is intended to receive at most three wafers 22. To securely receive the wafers 22, there are provided in the boat plate 21 three receiving slots 23 that are arranged one behind the other in the longitudinal direction of the boat plate 21 and are bounded laterally by retaining arms 24 and by a lower frame element 25 of the boat plate 21. The length of the retaining arms 24 is dimensioned such that they reach only up to about half the height of the inserted wafers.

[0032] To securely receive the wafers 22, receiving elements 26 that are oriented inward into the receiving slot 23 project from the retaining arms 24 and the lower frame element 25. A groove, into which the outer edge of the wafer can engage, is worked into that end face of each of the receiving elements 26 that projects into the receiving slot 23. Thus, the receiving elements 26 grip slightly around the respective outer edge of the wafer 22 in a U-shaped, V-shaped or fork-like form-fitting manner and thus secure the wafers 22 after insertion into the receiving elements 26 such that these, after insertion into the receiving elements 26, are held securely (FIG. 4). It is also possible for two wafers 22 to be simultaneously received in each receiving slot 23, making it possible to avoid deposition on the rear side of the wafer.

[0033] The boat plate 21 is produced from one piece by shaping processing methods, for example milling. It is clear that the thickness of the boat plate 21 must be greater than the thickness of two back-to-back wafers inserted into the receiving elements 26.

[0034] To securely receive the wafers 22, it is sufficient to have in each receiving slot 23 three such receiving elements 26, specifically as shown in FIG. 2 at the upper end of the respective left-hand retaining arm 24, approximately in the middle of the respective right-hand retaining arm 24 and in the respective right-hand third of the lower frame element 25. The exact position of these receiving elements 26 is not important, but it is essential, in order to securely receive the wafers 22 in the receiving slot 23, that three such receiving elements 26 be present.

[0035] In this manner, each vertically oriented wafer 22 is securely fixed three-dimensionally at three points and by means of its own weight, and flush with the boat plate 21, such that the wafers 22 cannot fall out in the event of movement of the boat plate 21 in an essentially vertical use position of the boat plate 21.

[0036] FIG. 3 shows a wafer boat or PECVD boat 27 that consists of a multiplicity of vertically oriented boat plates 21 arranged spaced apart from and next to one another and mechanically connected to one another. For the mechanical connection between the boat plates 21, there are provided bores 28 for receiving spacing and connecting elements (not shown) that are made of a nonconductive material such as Al.sub.2O.sub.3, quartz glass or ceramic in order to avoid short-circuits.

[0037] The boat plates 21 can be made of graphite, CFC or titanium and can easily be produced using known shaping processing methods.

[0038] The PECVD boat 27 according to the invention can also be used to carry out a rear-side coating using a back-to-back loading of the wafers 22, by placing or inserting two wafers 22 into each of the receiving slots 23 of each boat plate 21, with their respective rear sides in contact with one another.

[0039] By virtue of the fact that the wafers 22 are each held in the boat plates 21 at just three points, they are largely free at a defined distance from the receiving slot 23. This has the particular advantage that the wafers 22 are, to the greatest possible degree, thermally decoupled from the boat plate 21 or the PECVD boat 27. Thus, the heating power can reach the wafer 22 much better without first having to heat up the mass of the boat plate 21. This leads to a marked shortening of the heating-up and cooling-down processes and of the homogenization time.

[0040] By virtue of the inventive configuration of the boat plates 21, the mass-to-surface-area ratio has changed greatly in favor of the wafers 22. Compared to their mass, the wafers 22 have a much greater surface area than the boat plate 21.

[0041] The boat plates 21, or the PECVD boats 27 composed thereof, according to the invention can be used in a great many PECVD processes and are well suited especially to processes, in the field of photovoltaics, in which TMA, SiNOx and SiN layers are deposited.

[0042] The boat plates 21 according to the invention can easily be produced, in one piece including the receiving elements 26, from graphite, CFC (Carbon Fiber-reinforced Carbon) or titanium by shaping processing methods. The thickness of the boat plates 21 must be greater than the thickness of the wafers 22 that are to be inserted into the receiving elements 26.

LIST OF REFERENCE SIGNS

[0043] 10 Boat plate [0044] 11 Wafer [0045] 12 Milled-out portion [0046] 13 Rim [0047] 14 Retaining pin [0048] 20 Wafer holder [0049] 21 Boat plate [0050] 22 Wafer [0051] 23 Receiving slot [0052] 24 Retaining arm [0053] 25 Lower frame element [0054] 26 Receiving element [0055] 27 PECVD boat [0056] 28 Bore