DE102010032029A1 - Method for separating round wafer into rectangular chips for display panel of mobile telephone, involves forming horizontal parting lines vertical to vertical parting lines, from one edge to other edge of platen - Google Patents

Abstract

The method involves forming a center parting line (2-1) in a plan platen (1) along vertical parting lines (2-6-1-8,2-7-1-6,2-7-1-10,2-8-1-4) by laser, such that the platen is divided and two rectilinear edge portions are formed along the center parting line. The horizontal parting lines (2-2-2-5) are formed from one edge to other edge of the platen at preset intervals, to divide the rectilinear edge portions into several portions. All the parting lines (2-2-2-5) are formed vertical to the vertical parting lines such that platen is divided into several single platens.

Description

The invention relates to a method by which a flat plate made of a brittle material such as glass, ceramic or semiconductor material can be separated into a plurality of rectangular individual plates by introducing thermally induced voltages by means of laser. A generic method is in the DE 10 2007 033 242 A1 described.

It is known that it is possible to separate brittle materials by introducing thermally induced voltages by means of lasers. For this purpose, along predetermined separation lines for generating compressive stresses, a laser radiation is directed onto the material surface and guided along the course of the predetermined separation line. Subsequently, the heated zone is subjected to a coolant jet, whereby tensile stresses are generated. If the resulting voltage difference is above the breaking stress of the material and there is a defect at the starting point of the dividing line, cracking of the material from the defect is initiated. Should such a defect not due to existing microcracks, z. B. starting from a mechanical cutting edge, be present, a specific initial defect must be generated, for. B. by a diamond cutting wheel or a well focusable laser high energy density. For the latter, the processing laser or a second laser can be used. Depending on the internal structure of the material, either a targeted depth crack or a separation crack that completely penetrates the material can be achieved.

To z. B. in the manufacture of display panels for mobile phones and the like or in the manufacture of chips a plane plate in a plurality of equal rectangular individual plates, according to the prior art, the plane plate first along a plurality of mutually parallel first parting lines and then at an intersection angle of Offset 90 °, separated along several parallel second dividing lines. This results, given by the crossing points of intersecting at an angle of 90 ° dividing lines, rectangular individual plates whose side lengths are determined by the distances of the dividing lines.

Crucial for the quality of the individual plates thus produced is that the separation cracks form exactly along the predetermined separation lines.

In the DE 10 2007 033 242 A1 it is found that such quality defects occur at the crossing points. The forming separation cracks do not meet at the crossing points perpendicular to each other, that is, the course of the separation cracks deviates in the region of the crossing points of the course of the predetermined separation lines. This deficiency is attributed to the mutual influence of the thermally induced stresses along the abutting edges formed by the separation cracks. This problem is solved by spacing the strips created by the separation in the first direction.

The practice shows, however, that the resulting separation cracks also at their beginning, adjacent to the circumference of the plate to be separated, deviate from the course of the predetermined separation line, if they do not impinge perpendicular to the peripheral surface, which is given when the peripheral line of the plane plate of a rectangular Deviates form.

This is especially true when the circumferential line is curved. Planar plates with a round peripheral line, such as wafer slices, which are to be singulated into individual chips, are of particular practical importance. Theoretically, the plane plate z. B. also have the shape of a triangle, a polygon of an ellipse or a freely shaped peripheral surface. In all of these cases, at least some of the dividing lines do not impinge perpendicularly on the peripheral surface.

The resulting problems are based on a round plan plate, which is separated along ten dividing lines, based on 1a and 1b be explained. According to the prior art, the separation of a plane plate takes place 1 , as already described, along dividing lines 2 which are in mutually perpendicular directions parallel to the diameter of the plane plate 1 are arranged. Starting from the circumferential area, starting in sequence, first all the dividing lines 2.1 to 2.5 in one direction and then all the dividing lines 2.6 to 2.10 separated in the other direction. All dividing lines 2 , except one, whose course coincides with the diameter of the plane plate 1 coincides, with an applied at the intersection of the peripheral surface tangent an entrance angle α of not equal to 90 °, which becomes smaller with increasing distance from the diameter.

Since the thermally induced with the separation process voltages in the starting point of the dividing line, ie in the edge region of the plane plate in the direction of a starting point to the contact surface tangent (hereinafter in the tangential direction) propagate and only the perpendicular to the dividing line projected component of the voltages for the Crack opening force of a separation crack along the predetermined separation line is determined, the formation of the separation crack is deflected from the predetermined separation line with increasing distance from the diameter. In addition, starting from one critical distance, which depends on the thickness of the material, the scribe and the cutting parameters, the crack opening force for starting the separation process too low.

Another problem may arise, in particular when singulating into chips with minimal edge lengths <1 mm. In experiments carried out it was observed that when separating in the edge region of the induced separation crack in its course deviates from the predetermined separation line and always turns towards the edge. One possible explanation is the symmetrical propagation of the thermally induced stresses perpendicular to the dividing line, which is opposed by a difference in resistance, depending on the amount of material adjacent to the dividing line on both sides. The crack runs in the direction of the lower resistance and turns off.

The invention has for its object to find a method for separating a plane plate with a deviating from a rectangle perimeter in rectangular items with which thermal stresses are induced by means of laser, which lead to the formation of separation cracks, which are highly accurate along the course of predetermined Spread dividing lines.

This object is for a method for separating a plane plate made of brittle material into rectangular individual plates, in which due to thermally induced voltages with laser plan plate dividing separation cracks along mutually perpendicular, formed with a predetermined spacing dividing lines by a directed onto the plane plate laser beam at least partially in succession along the parting lines, achieved in that in a first step, from a starting point on the peripheral surface of the plane plate ago starting with a separation along a parting line the flat plate is divided into two parts, so that along this separation crack two straight edges , In a second step, in each case starting from starting points on the resulting edges along all this perpendicular separating lines separating cracks are introduced, whereby a plurality of parts with further rectilinear edges is formed and in one third step, all separating cracks are introduced along the perpendicular thereto separating lines, which finally the plane plate is divided into a plurality of individual plates.

Advantageously, the separation cracks are introduced in their time sequence so that they are each introduced successively along the dividing line, which is the halving of the edge of the part, which is to be divided in each case with the separation in two parts closest.

For a shortening of the process time, it is advantageous if several separation cracks, which divide different parts, are generated simultaneously in one direction.

Further shortening the process time can advantageously be introduced in the third step, the separation cracks along a parting line from one edge of the plane plate to the other edge of the plane plate.

It is also advantageous if between the individual steps, the resulting parts are separated by a stretching process.

Also, an initial defect should be introduced at the starting point of the parting lines prior to the introduction of the parting cracks.

The method for separating a round flat plate can be used particularly advantageously. The first parting line is then set along the diameter so that the first parting line halves the round plane plate.

Advantageously, the first separation crack is also predetermined in the direction perpendicular thereto, and all further separation lines are set relative to one another in their distance from one another.

The method will be explained in more detail below by way of example with reference to the drawings.

Show it:

1a B are sketches for explaining a cutting regime according to the prior art

2a - 2c Sketches for explaining a cutting regime according to the method of the invention

3a - 3b a round flat plate with dividing lines, which are marked so that the regime, are introduced after the separation cracks along these dividing lines, recognizable.

The procedure is subsequently based on a round plane plate 1 explained. However, it is applicable for separating plane plates regardless of their peripheral shape and advantageously suitable for those whose circumference deviates from a rectangle.

Particularly suitable is the method for separating round wafer slices into individual rectangular chips.

The introduction of the separation cracks is equal to that described in the prior art Method by a laser beam is directed onto the surface of the plane plate and is guided from a starting point along the predetermined separation lines relative to the plane plate. The method differs decisively by the regime of introducing the separation cracks, which is determined by where the separation cracks are introduced starting and in what order.

1a shows a round plane plate 1 , here by way of example with ten dividing lines 2.1 - 2.10 , The parting lines were numbered in an order as parting lines are introduced along these parting lines according to a prior art regime as already explained.

1b shows, to explain the problem to be solved schematically, the resulting according to this regime of the prior art voltages each at the starting point of a dividing line.

With the method according to the invention, a plane plate, as in 1a shown, with a same arrangement, or a same pattern of dividing lines divided into several individual plates.

In the 2a - 2c is a plane plate 1 shown, in which the gradual introduction of the separation cracks is shown. To ensure the clarity of the presentation, only three dividing lines in each direction should be introduced.

In the 3a and 3b is a plane plate 1 shown with 18 dividing lines, in particular to show the time sequence of the introduction of the separation cracks along dividing lines in one direction.

The basic idea of the method according to the invention is that each separation tear, which later limits one of the individual plates, should start from a starting point in which the thermally induced stresses propagate perpendicular to the separation crack. This is certainly the case if the dividing lines, along which the separating cracks are to run with high precision, impinge perpendicularly on a rectilinear edge. In addition, the division of the plane plate should be advantageous 1 be done so that on both sides of each separation crack at least at the starting point adjacent as far as possible the same amount of material.

In a first step, presented in 2a , becomes the plane plate 1 divided into two parts by a separation tear, creating two straight edges. Advantageously, the division is done so that the plane plate 1 halved. If the plane plate is a round plane plate, then a halving separation line necessarily coincides with the diameter of the round plane plate, whereby it runs perpendicular to the tangent to the peripheral surface. Ideally, the stresses arising at the starting point, as well as from a rectilinear edge perpendicular to the parting line, run perpendicular to the parting line. Subsequently, the resulting in the first step, two parts z. B. with the in the DE 10 2007 033 242 moved apart stretch method described. The preferred distance to which the two parts are placed is between 5-10 microns.

In a second step, shown in 2 B , Starting from the resulting two edges, all separation cracks along the dividing lines are introduced, which extend in a first direction, perpendicular to these two edges. That is from the middle of the plane plate 1 from each along a dividing line cracks are generated with an opposite sense of direction.

Advantageously, initial defects are each set at the beginning of the predetermined separation lines. This can be done mechanically by means of diamond or carbide scraper or without contact by means of laser. In the now following separation process, the separation cracks are advantageously not successively introduced along adjacent separation lines, but each as far as possible halved by the separation already formed parts. Advantageously, the first parting line, along which a separation crack is introduced in the second step, is predetermined along the area bisecting line of the two resulting semicircular parts and the position of the parting lines parallel thereto is established starting from this parting line. Over the entire length of the separation crack along this first parting line, the amounts of material on both sides of the separation crack are the same. All other separation cracks in the same direction are introduced successively with respect to the part to be separated in each case along the parting line, which lies closest to the center of the edge of the part. Thus, at least at the starting point of each separation crack, the amounts of material on both sides of the separation cracks are almost the same. The process continues until all separation cracks have been introduced along the parting lines in the first direction. This approach reduces the differences in the material resistance in the directions of propagation of the induced voltages and thus ensures a highly accurate rectilinear course of the separation cracks along the course of the predetermined separation lines. The result of the second step is the plane plate 1 in a variety of parts, namely in strips, separated.

Thereafter, in a third step, the separation of the strips in individual plates by these are divided perpendicular to the resulting edges.

Advantageously, initial defects on one edge of each strip are previously applied to the set predetermined dividing lines. Possible designs are minimal defects in the edge area, but also a continuous scribe within the parting line over its entire length.

After setting the initial defects, there is advantageously a further stretching process which is intended to prevent edge contact during the subsequent separation process.

In the third step, shown in 2c , Now, in analogy to the second step, all separating cracks are introduced starting from the resulting edges along the dividing lines, which run in the second direction. In contrast to the second step, where a separating line is formed along a dividing line, in the third step along a dividing line, several dividing cracks are formed in succession, which are delimited by the rectilinear edges of the strips produced in the second step. These edges are exactly perpendicular to the newly created separation cracks. Since the resulting individual plates adjacent to the edge of the plane plate are not rectangular in shape, they are waste, so the quality of a delimiting separation crack is not of concern. It does not matter if the dividing lines adjacent to the edge parts follow the course of the dividing line or if they may not even be triggered. Since the subsequent separation crack emanates again from an edge extending perpendicular to the separation crack, the subsequent separation crack again has the required quality.

The separation cracks, which are introduced in the third step, therefore need not necessarily from the center of the plane plate 1 introduced with opposite sense of direction, as in 2c but can also be seen from the edge of the plane plate 1 be introduced with the same sense of direction, which would even lead to a comparatively shortening of the process duration.

As a result, each of the separation cracks in the process, which later defines a rectangular piece except for the first, forms at a starting point perpendicular to a straight edge, optimally introducing the thermally induced stresses for a defined course of the separation cracks along the predetermined separation lines.

In 3a All generated separation cracks are shown, with the regime after which they were introduced by symbols and the sequential numbering of the separation cracks 2 is shown. In contrast to that on the basis of 2a - 2c explained regimes are here, as also already stated, the separation cracks, which were introduced in the third step, from the edge of the plane plate 1 from introduced. The starting points in one direction were each symbolized by a square and the direction of the introduction of the separation cracks is shown with an arrow. It is clear that the small number of separation lines shown here only serve to provide a clear representation and can be practically many times larger. The separation cracks were numbered consecutively with increasing numbering, as they are successively introduced along the dividing lines. Separation cracks with the same numbering can be introduced at the same time or in succession before the separation cracks of the next higher numbering are introduced. Between the three described steps of the method is in each case a relative movement between the cutting tool, that is, on the surface of the plane plate 1 directed laser beam and the workpiece, ie the plane plate 1 , necessary. In the example described is a 90 ° rotation, preferably the plane plate to be machined 1 , For the simultaneous introduction of separation cracks, multiple laser beams can simultaneously on the plane plate 1 be directed.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007033242 A1 [0001, 0005]
• DE 102007033242 [0034]

Claims (8)

Method for separating a plane plate ( 1 ) made of brittle material in rectangular single plates, in which due to thermally induced voltages with laser the plane plate ( 1 ) dividing separation cracks ( 2 ) along mutually perpendicular, formed with a predetermined spacing separating lines by one on the plane plate ( 1 ) directed laser beam at least partially successively along the parting lines, characterized in that - in a first step, from a starting point on the peripheral surface of the plane plate ( 1 ) starting with a separation line ( 2.1 ) along a parting line the plane plate ( 1 ) is divided into two parts, so that along this separation ( 2.1 ) create two straight edges, - that in a second step, starting from starting points on the resulting edges along all this perpendicular separating lines separating cracks ( 2.2 - 2.5 ) are introduced, whereby a plurality of parts with further rectilinear edges is formed and - that in a third step, all separation cracks along the perpendicular thereto separating lines ( 2.6.1-10 to 2.8.1-10 ), whereby finally the plane plate ( 1 ) is divided into a plurality of individual plates. A method according to claim 1, characterized in that in the individual steps the separation cracks ( 2 ) are introduced in their temporal sequence so that they are each successively introduced along the dividing line, which is the halving of the edge of the part, which is to be divided into two with the dividing line in each case closest. Method according to claim 2, characterized in that several separation cracks ( 2 ) are generated simultaneously in one direction. A method according to claim 1, characterized in that in the third step, the separation cracks ( 2.6.1-10 to 2.8.1-10 ) along the dividing lines from one edge of the plane plate ( 1 ) to the other edge of the plane plate ( 1 ) are introduced. A method according to claim 1, characterized in that between the individual steps, the resulting parts are separated by a stretching process. A method according to claim 1, characterized in that at the starting point of the separating lines before the introduction of the separation cracks ( 2 ) an initial defect is introduced. Use of a method according to one of claims 1 to 6, for separating a round flat plate ( 1 ), characterized in that the position of the first parting line with the diameter of the plane plate ( 1 ) coincides. A method according to claim 7, characterized in that the separating lines are predetermined so that two of the mutually perpendicular separating lines with the diameter of the plane plate ( 1 ) coincide and all other dividing lines are determined in their distance from each other based on these.

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