DD224126A1 - VACUUM CLAMPING DEVICE FOR SEMI-FINISHED DISCS WITH CROPPED SURFACES - Google Patents

Abstract

The invention relates to a vacuum clamping device for semiconductor wafers with curved surfaces. It is an object and object of the invention to increase the number of workable semiconductor wafers and to reduce the risk of injury of photo templates and semiconductor wafers in the contact and Abstandskopie by the semiconductor wafers are stretched so that their surface is plane-parallel to the lying over this photo template. According to the invention this is achieved in that in the Aufspannflaeche a known clamping table, an annular groove is introduced such that it includes the majority of Vakuumansaugoeffnungen, which serve for clamping, and in this annular groove a ring is arranged resiliently and vertically movable. The semiconductor wafer is first placed on this ring and then sucked onto the clamping surface by the vacuum, the ring being pressed into the clamping table. figure

Description

Vacuum clamping device for semiconductor wafers with curved surfaces

Field of application of the invention

The application of the invention is in the field of semiconductor production

In this case, by exposure by means of a template in an exposure device, a pattern in a photosensitive resist, which is located on the semiconductor wafers, generated.

The invention is preferably used; _; to be able to clamp deformed semiconductor wafers in these processes by means of vacuum on adjusting devices.

Characteristic of the known technical solutions

It is customary to produce certain patterns in photosensitive resist deposited on a wafer in the manufacture of integrated circuits by exposure by means of a template. These lacquer layers are used in the further process sequence as Ätzmajsken for oxide or metal layers. The exposure of the paint is predominantly by contact copy, i. The stencil and the semiconductor wafer to be exposed are brought into close contact during the exposure.

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Before exposure, the stencil and the wafer are positioned with respect to each other, and must be moved a small distance apart. To this end, the wafer must be aligned with the template to allow simultaneous focusing γοη two template and slice points through the Justierjnikroskop.

Particularly high are the requirements for the plane-parallel alignment of stencil and calender disc in the distance copy, which also during the exposure a small and very uniform distance from the template and the fest.auf the clamping plate held semiconductor wafer must be maintained. Template and wafer alignment is generally accomplished by holding the planar wafer firmly on a chuck table and bringing it into close contact with the stencil, e.g. by mechanical pressing or by vacuum pressure .. -.

A disadvantage of this handling is that semiconductor wafers, which are discarded by hot-melt temperature processes or have edge seams, can not be held in place by vacuum on the worktable, which leads to a high failure of semiconductor wafers and thus to a drop in yield in the production of microelectronic components.

In order to hold them securely on the chuck table by means of vacuum, slightly deformed semiconductor wafers are aligned and brought into close contact with the template several times. -

ISfachfachig, in this method is that caused by the repeated alignment and the contacts of the deformed semiconductor wafer with the template violations of the lacquer layer on the semiconductor wafer and the photomulsion layer of the template. High wear on the stencils and exposure

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Errors on the semiconductor disks are the negative poles that lead to a decrease in yield in the production of microelectronic components. It has also been proposed to arrange a stable metal plate or a stable metal ring outside the adjusting device, for the purpose of aligning and securely holding the deformed semiconductor wafer swung on the worktable in the adjusting device and swung out again after clamping.

This method is associated with greater technical complexity and at the same time means an extension of the cycle time, since an additional operation for the pivoting in and out of the surface plate is required.

Object of the invention

It is an object of the invention to increase the number of workable semiconductor wafers and to reduce the risk of injury of photo templates and semiconductor wafers in the contact and Abstandskopie to achieve a saving of semiconductor wafers and photo templates and to achieve by a yield increase, a more cost-effective production of semiconductor devices.

Explanation of the essence of the invention

The invention has for its object to provide a vacuum chuck for semiconductor wafers with curved surfaces, whereby the processing of semiconductor wafers with a deformed surface or with lacquer layers of different thickness, e.g. With edge beads on exposure means is made possible by the fact that the semiconductor wafer is stretched so that their surface is plane-parallel to a lying over this photo template.

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To, solution of the problem is used in a conventional manner. A circular clamping table. This worktable has a planar rake face, are placed in. Which a number of vacuum suction holes einge- ^r.

According to the invention, the object is achieved in that int the top of the planar clamping surface an annular groove is introduced. This annular groove includes at least the largest part of the vacuum suction. A ring, whose cross section corresponds to the cross section of the annular groove substantially, is arranged vertically movable in this annular groove. To limit the vertical mobility of the ring has stops which correspond with corresponding counterparts in the clamping table * /

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Under the ring a number of compression springs is arranged, whereby the arrangement of a compression spring from the diameter of the ring is possible.

The ring of the ring and / or the arrangement of the stop or the counterpart were chosen so that when spring-loaded pressure of the ring against the stop, i. In the pushed out state, the ring protrudes beyond the clamping surface · The height of the ring above the clamping surface is equal to the amount by which the. Semiconductors in the region of the ring, based on their lowest point, when they rest on the support table, are bent.

The operation of the device according to the invention is to be seen in that when laying of semiconductor wafers initially enters a linear contact between the ring and the semiconductor wafer. Due to the fact that disk bends in semiconductor wafers are always concave and thus substantially concentric with the center, the ring seals both planar and twisted wafers between the rake face and the disk string.

Thus, vacuum can be applied to tension the wafer on the rake face. Since most of the Vakuumansaugöffnungen is located inside the Hinges, arises in the space between the bottom of the wafer and the clamping surface, which is bounded by the ring to the outside, first a negative pressure. As a result, the spring-loaded upwardly pressed ring is pushed down and the wafer settles on the clamping surface. Bent discs are pulled straight according to the surface design of the clamping surface.

A particular embodiment of the device according to the invention provides for _r that the ring is lockable in its upper stop.

This makes it possible to deform the disc in an artificial manner concave. For example, if a convex Scheibenyerbiegung present in excessively high, the semiconductor wafer can be bent in the other direction to the extent that their original convex curvature is minimized by this particular embodiment.

embodiment

The invention will be explained in more detail below with reference to an exemplary embodiment. In the accompanying drawing, a cross-section through the vacuum clamping device according to the invention is shown * This device represents a functional group within a positioning and BeIichtungseinrichtung.

It consists of a worktable 1, on the clamping surface 2, a semiconductor wafer 3 is sucked by means of vacuum. The worktable 1 is with the help of a Kugelkalottenlagerung 4 with respect to a photo template

swiveling · The photo stencil 5 is located almost parallel to the plane of the clamping surface 2 and is firmly clamped in a holder 6. In the clamping surface 2 Vakuumansaugöffnungen 7 are introduced, which are connected to a vacuum line 8. Including most of these vacuum suction openings 7 is located in the chuck table 1 and in the clamping surface 2 an annular groove 9. This annular groove 9 has a rectangular cross-section, in which a stop ring 10 is inserted ·

In this annular groove 9, a ring 11 is inserted vertically movable.

This ring 11 has an Ir-shaped cross section aufj wherein the horizontal leg 12 of the cross section is arranged so that this onter attacks the stop ring 10. ,,, -

under the ring 11, a plurality of compression springs 13 is introduced, which press the ring 11 with its leg 12 against dsn stopper ring 10 upwards, and hold in this position. ,

The gap which must necessarily exist between the ring 11 and the annular groove 9 for the purpose of vertical mobility, is designed in terms of its dimensional tolerance and its surface quality so that it is tight for the vacuum to be sucked. Of course, here it is possible to use .Dichtungsmaterialien. ·. If a semiconductor wafer 3 is now placed on the setting table, the ring 11 is pressed upwards against the stop ring 10 by the compression springs 13, thereby sealing the space between the clamping surface 2 and the underside of the semiconductor wafer 3. Subsequently, the vacuum line 8 and thus the vacuum opening openings 7 are subjected to vacuum. This creates a vacuum in the space between the clamping surface 2 and the underside of the semiconductor wafer 3,

causing the atmospheric pressure the semiconductor wafer

3 pushes plan onto the clamping surface 2. In this case, the ring 11 is pushed down into the annular groove 9.

By this means, each wafer, i. straight and within limits arbitrarily bent are clamped on the worktable 1. Bach the clamping is now lying semiconductor wafer 3 by the Kugelkalottenlagerung

4 is aligned plane-parallel to the photo template 5 and the entire worktable 1 is moved upwards until the ring seal 14, which is required for the contact copy, touches the photo stencil 5. After that, the exposure process can take place.

Claims (2)

   - 8th - Srfindungsarispruch. 1.' Vacuum clamping device for semiconductor wafers with curved surfaces in exposure devices with a vertically movable circular clamping table having a clamping surface with vacuum suction openings, characterized in that in the clamping table (1) concentric with its center, at least the largest part of the suction suction openings (7 ), an annular groove (9) is arranged, in which a ring (11) is introduced vertically movable, under which a number of compression springs (13) is arranged and which has an upper stop (10), wherein, the height of the ring (11) and / or .the arrangement of .Anschlages (1Q) is selected so that at spring-loaded pressure of the ring (11) to the stop (10) of the ring (11) protrudes above the clamping surface (2) by an amount , which is at least equal to the amount of Scheibenverbiegung in the region of the ring (11) relative to the lowest point of a resting disc 2. Vacuum clamping device according to item 1, characterized in that the ring (H) in the position of the stop (10) can be detected. - See 1 page drawings -