Radiation-emitting semiconductor component and method for the production thereof

Translation of description of equivalent WO 2004032248 A2

p0001description

p0002Radiation-emitting semiconductor device and process for its preparation

p0003The invention relates to a radiation-emitting semiconductor component having a radiation-transmissive substrate, on the underside of a radiation-generating layer is disposed. The substrate has inclined side on surfaces. Furthermore, the invention relates to a process for the preparation of the radiation-emitting semiconductor component.

p0004From document US 5,087,949 a device of the type mentioned above is known, in which the radiation-generating layer on the underside of the substrate has only a very small lateral extent, so that the radiation source for optimizing the shape of the substrate is regarded as a point light source. Accordingly, the substrate is shaped so that the falling of the light source from the inside of the boundary surfaces of the substrate always possible light incident at an angle which is smaller than the critical angle for total reflection. This ensures that the largest possible part of the light generated by the radiation-generating layer is transmitted through the substrate. The optimization of the shape of the substrate with respect to a substantially point source of light on the underside of which leads to such a substrate is poorly suited for radiation-generating layers having a large-area expansion.

p0005From document US 5,187,547 a device of the type mentioned is known in which on the underside of a radiation-transparent substrate, a large area listed brought radiation-generating layer is arranged, whereby the amount of light generated overall against a punctiform gen light source is significantly increased. The shape of the substrate is selected so that between the top and the bottom runs a continuous oblique edge, from which the light from the interior of the substrate is coupled to the outside. The continuously tapered from top to bottom side edge of the substrate has the disadvantage that the production of a variety of such substrates from a wafer consisting of a material suitable therefor, leading to a reduced yield of the wafer surface.

p0006The located between two substrates V-shaped incisions are namely usually sawn using a suitable saw, which leads during sawing of the substrate to a non-negligible lateral removal of material, whereby the usable area of ​​the single substrates decreases adversely. Moreover, it is a disadvantage with a V-shaped saw blade to cut through a substrate entirely, since in this case the saw blade can easily be damaged.

p0007It is therefore an object of the present invention to provide a radiation-emitting semiconductor component which can be manufactured with a high yield area of ​​the wafers, and is suitable for high light outputs.

p0008It is another object of the invention to provide a method for producing position of the component.

p0009These objects are achieved by a radiation-emitting semiconductor device according to the patent claim 1 and by a method for its production according to claim 20. Advantageous embodiments of the invention are given in the dependent claims.

p0010There is provided a radiation-emitting semiconductor component having a radiation-transmissive substrate. On the underside of the substrate a radiation-generating de layer. The substrate is at least for the generated radiation in the radiation-generating layer permeable. Further, the substrate has inclined side surfaces. The refractive index of the substrate is greater than the refractive index of the radiation-generating layer. This ratio of the refractive indices is especially true when the wavelength of the radiation generated in the radiation-generating layer.

p0011Due to the difference in the refractive indices results in a non-illuminated area in the substrate, no photons are coupled directly into the development of radiation-generating layer of. This thus created blind spots resulting from the fact that due to the laws of refraction, the light can not be coupled at any angle in the substrate, but that this is a minimum critical angle, which is determined by the refractive index difference.

p0012In the Invention preferably is remote from the substrate side of the radiation-generating layer to the mounting of the component (upside-down mounting). Conveniently, for this purpose a corresponding mounting surface is provided on the side remote from the substrate side of the radiation-generating layer.

p0013In the unilluminated region comprises the substrate substantially perpendicular side surfaces. Among those side surfaces are to be understood, which can be performed with the resources available as possible perpendicular to the underside of the substrate. Here are exemplified the means sawing of the substrate by means of a straight blade or breaking of the substrate from a larger substrate for

p0014Purpose of separation.

p0015Such a device has the advantage that it can be produced due to the disposed in a side portion of the substrate perpendicular lateral faces with significantly less floor space. Due to the vertical side faces, for example, on the underside of the substrate a base may form, the portion of the substrate can be limited to a partial region of the substrate thickness, which reduces the lateral removal of substrate material to the required minimum. The oblique side surfaces are namely required in an optimum coupling-out of light from the interior of the substrate. However, as in the blind spot, no light must be coupled out of the substrate, without adversely affecting the light output, at this point, the external shape of the substrate can be optimized in terms of improved manufacturability. Such simplified or improved producibility, which may mean in particular an improved area yield in the manufacture of a plurality of individual substrates from a large substrate by dicing, can be ensured that the substrate to be separated, for example by breaking or by straight sawing in the vertical edges can.

p0016When straight sawing has a much lower lateralis len material removal as during sawing of the oblique edges. If the separation effected by breaking the substrate at the location of the straight side edges, the lateral removal of material and thus the area yield on the large substrate is further optimized.

p0017There is accordingly provided a method for producing the component, in which V-shaped trenches in a substrate by means of a suitably shaped saw are sawn. It will, however, ensure that a residual thickness of the substrates remains tes throughout. In a subsequent step, the substrate is diced into smaller individual substrates, along the V-shaped grooves.

p0018This method has the advantage that by reducing the depth of the V-shaped grooves compared to the out of the

p0019Prior-art substrate of the lateral removal of material as well as the wear on for sawing V- fδrmiger trenches suitable sawing can be significantly reduced.

p0020The separation of the substrates, for example, by means of a straight blade, which has a substantially smaller committee than a V-shaped blade.

p0021In addition can be carried out the separation of the substrates even by crushing, whereby the ESC is reduced even further.

p0022In one embodiment of the device the perpendicular side areas form a base on the underside of the substrate, on its upper side adjacent to the inclined side surfaces. Such a shape of the substrate has the advantage that the whole non-illuminated region of the substrate can be used for the vertical side surfaces through the base on the underside of the substrate. Furthermore, such a design has the advantage that the V-shaped depressions supply can be cut between two individual substrates from one side and below is only a single step for machining the surface of the substrate necessary. In another embodiment of the component, the upper limit of the unilluminated region coincides with the upper limit of the base. As a result of

p0023Advantage that the entire height of the non-illuminated portion can be used for the formation of the socket. The higher the base of the substrate is formed, the less deep the V-shaped incision between two individual substrates must be effected and the more advantageous, the area yield are designed on a large substrate.

p0024The base can also be increased over the unlit area of ​​the substrate addition, still further, which brings further advantages in terms of the method of manufacture. However, this happens at the expense of out-coupling of Light from the substrate for which the inclined side surfaces are advantageous.

p0025According to another embodiment of the device the radiation-generating layer covers the substrate lower side to an outer free edge having a finite width. By the radiation-generating layer, the bottom almost completely covered, it is ensured that a corresponding amount of power in the radiation-generating layer due to the enlarged surface can be coupled, which increases the luminous efficacy of the radiation-generating layer.

p0026By the radiation-generating layer does not quite to the edge of the underside of the substrate, can be reached that the radiation-generating layer, which is very sensitive to mechanical damage, because it is, for example, covered only with a thin silicon nitride layer in the separation of individual substrates can be protected from a large wafer from damage.

p0027Furthermore, the formation of a free edge on the underside of the substrate has the advantage that it is possible through the selection of a suitable width for this free edge determine the geometric extent of the unilluminated substrate region. The smaller the extent of the radiation-generating layer on the underside of the substrate, the greater is the unilluminated substrate region, since this is determined by the critical angle, which in turn depends on the refractive index difference, and, through the range from the edge of the radiation-generating layer to the edge of the substrate over which the angle causes a widening of the unilluminated substrate region toward the substrate edge.

p0028In another embodiment of the device the radiation-generating layer has bevelled edges, which are designed so that lateral to the substrate emitted, in the radiation-generating layer generated light is reflected toward the substrate.

p0029In the shaping of the radiation-generating layer is its own invention to see who can advantageously be applicable irrespective of the specific shaping of the substrate and also independent of the refractive index difference between the substrate and the radiation-generating layer, since the beveled side edges of the radiation-generating layer, an advantageous deflecting the generated radiation in the direction of the substrate results. This advantageously allows the light output of the radiation-generating device can be increased.

p0030Accordingly, only a substrate is necessary for carrying out the invention with respect to the shape of the radiation-generating layer on the underside of which a radiation-generating layer is applied.

p0031To provide for the reflection of radiation in the right direction, it is advantageous if Include the beveled side edges of the radiation-generating layer with the substrate underside an angle between 20 and 70 °. Preferably, it is advantageous to choose an angle between 30 and 60 °. In the mentioned angular range, it is also possible to specify an appropriate angle for total reflection. In this case, this angle depends on the material from which the radiation-generating layer is surrounded. Depending on the refractive index difference between the radiation-generating layer and the vicinity thereof, a suitable angle for total reflection of the light generated in the radiation-generating layer on the sloping side edge can be selected.

p0032Moreover, it is also possible to cause the total reflection by an optically reflective material on the beveled side edge. For example, the chamfered Side edge to be covered with a layer containing aluminum or silver. For this purpose, a passivation layer between the semiconductor and the metal is required.

p0033In another embodiment of the device, said embodiments, each on its own or in combination with each other can come into play particularly advantageous contact elements are arranged on top of the substrate. Moreover, the substrate material is selected so that the transverse conductivity, ie, the conductivity leads laterally to the substrate lower side to a conical extension of a injected from the contact element into the substrate current. A conical extension is obtained in particular due to the strate anisotropic conductivity of the substrate. A suitable material for the substrate is, for example, silicon carbide.

p0034Further, the contact elements are so spaced from one another in that the current expansion cones touch each other in a depth in which the total cross sectional area of ​​the substrate is energized. Accordingly, the contact elements are so arranged that for a full-surface as possible energization of the substrate is already available at a relatively shallow depth of about described current cross-sectional area below the substrate surfaces before. Secondly, should that depth at which a full energization of the substrate cross-sectional area is present, be the same size as that depth in the substrate, wherein the current expansion cones touch each other.

p0035In the event that the current expansion cones of the individual

p0036Contact webs already overlap at a depth where not the entire substrate cross-sectional area is energized, the disadvantage would arise that with a full energization of the substrate in a relatively large depth of a high forward voltage would result, which would be detrimental to the electrical properties of the component , While it could also in this case, a large current flow carried out of the substrate in a relatively small depth below the substrate surface, but then would have to be raised to the surface of the substrate, the number of the lands, which would affect parts the light output from the surface of the substrate downstream, since the contact webs usually not fully transparent or reflective are.

p0037In the arrangement of the contact elements on the surface of the substrate is an invention to see which can be applied independently of the base form on the bottom of the substrate or of a faceting of strahlungserzeu- ing layer on components of the type mentioned.

p0038In one embodiment of the device, the contact elements in the form of conductor tracks are formed which extend along nested squares. The squares have equidistant from each other and mutually parallel edges. This form of the contact elements has the advantage that a uniform current supply to the entire substrate surface can take place. Moreover, said structure is photo easy to realize.

p0039In one development of this embodiment of the device, the conductor tracks can be energized according to the substrate surface to have mutually different widths. In particular, it is advantageous if the inner conductor tracks of the squares are narrower than the conductor tracks of the further outward squares. Since the conductor tracks on the further outward squares have to energize the substrate surface underlying the Seitenanschragung, a larger substrate surface must be energized by these conductor tracks. To ensure a sufficient contact area between the interconnects and the substrate here, it is advantageous to carry out the broad external interconnects, as the inner. requires a broadening of the inner conductor tracks on the account of the electric properties sary degree addition is not advantageous, since in this case the optical properties of the device would suffer.

p0040In one embodiment of the device, the substrate contains silicon carbide. Silicon carbide as the substrate material has the advantage that it has a good electrical conductivity. It also has the advantage that it enables the deposition of gallium nitride as a material for semiconductor single laser or light emitting diodes to blue light.

p0041Further, it is advantageous if the substrate is of the hexagonal 6H silicon carbide polytypes consists. Hexagonal 6H silicon carbide has the property that the electrical conductivity perpendicular to the crystallographic c-axis, this is the axis which is perpendicular to the surface of the substrate, about three times as high as parallel thereto. This particular results in the advantage that current expansion cones arise which enable a uniform energization of the substrate.

p0042A uniform energization of the substrate is particularly advantageous if the radiation-generating layer with high currents to be applied to produce the highest possible amount of light, with the aim.

p0043Furthermore, it is advantageous, especially in combination with a substrate made of silicon carbide, if the radiation-generating layer contains gallium nitride. The material is not limited to gallium nitride, but may also contain waste conversions of gallium nitride, in particular semiconductor materials based on gallium nitride. Here are, in particular gallium nitride, Galliumaluminiumnitrid, indium and p- or n-doped variants of these materials. Gallium nitride and and-called variations thereof have the advantage that they allow the realization of radiation-producing layer, which emit in the particularly attractive wavelength range of blue light.

p0044The present invention particularly relates to devices semiconductor, in which the base substrate has a width B of at least 300 microns.

p0045This large-area substrates have the advantage that a relatively high current for the energization of the radiation-generating layer may be used, as sufficient area, and therefore, a sufficiently low ohmic resistance can be obtained.

p0046This is to optimize the series resistance and thus the operating voltage and the efficiency of the component manages.

p0047The invention is further illustrated with reference to embodiments and the associated figures. In the figures, like reference numerals designate elements which einan- the same or whose operation is similar to today.

p0048Figure 1 shows an example of a device in a schematic cross-section.

p0049Figure 2 shows an example of a computer simulation on the extraction efficiency of components according to FIG. 1

p0050Figure 3 shows the arrangement of contact elements in a schematic cross-section.

p0051Figure 4 shows the arrangement of conductor paths in a plan view of the top of the substrate.

p0052Figure 5 shows an example of a further embodiment of conductor paths in a plan view of a substrate. Figure 6 shows a portion of Figure 1 with a bevelled side edge of the radiation-generating layer is shown.

p00537 shows a substrate during the execution of a method for manufacturing the component.

p00541 shows a substrate 1 which is covered on the underside of a radiation-generating layer 2. FIG. The substrate 1 has on the bottom a width B. Further, the substrate 1 has on the upper side a reduced width b. Further, the Substart has 1 inclined side surfaces. 3 It is particularly advantageous if the width B of the substrate lower side has a value from 300 to 2000 microns. For further considerations, a substrate width B is to be used as a basis of 1000 microns. The inclined side surfaces 3 close to the substrate bottom an angle c a; complementary to the angle θ is located, (shown in phantom), the inclined substrate surfaces with the substrate normal to include and which is plotted in Figure 2, where the extraction efficiency is discussed. On the underside of the radiation-generating layer 2, a contact layer 17 is applied which can be as basic material for the radiation-generating layer 2, a p-mirror contact in the case of gallium nitride. This means that the underside of the radiation-generating layer 2 is associated with the positive electrical contact. The p-contact mirror fulfills two functions. Firstly, it ensures a large-area, low-resistance contact with the radiation-generating layer 2. On the other hand, this contact layer 17 has also reflective properties, ie, that the light generated in the radiation-generating layer 2 is reflected by the contact layer 17 and thus through the substrate 1 from the component can be coupled.

p0055As the figure 1 can be seen, the radiation-generating layer 2 is not de entire surface on the bottom of the sub- applied strats 1, but there is a free edge 7 is present. The free edge 7 is not covered by the radiation-generating layer 2. FIG. It is to be assumed below that the material of the substrate 1 is a hexagonal silicon carbide. But there are also other suitable materials into consideration. It should further be assumed that the material of the radiation-generating layer 2 of gallium nitride or a gallium nitride-based semiconductor material for the production-emitting in the blue spectral range the light emitting diodes and is suitable for semiconductor lasers.

p0056applies to the refractive indices of these materials, that the refractive index of silicon carbide is nl = 2.7 and compared to the refractive index of gallium nitride n2 = 2.5. Accordingly according to the refractive index of the substrate 1 is larger than the refractive index of the radiation-generating layer 2. This refractive index difference results in that there are regions in the substrate 1 that are not illuminated by light from the radiation-generating layer 2. FIG. These unilluminated substrate regions 4 result from the geometrical optics laws that determine the angle at which can arrive at different refractive index radiation from one material to the other material. In the present case, there is a so-called "blind spot", which is sized with δ. The materials exemplified here, the dead angle δ about 22.2 °.

p0057Starting from the outermost edge of the radiation-generating layer 2 obtained as a wedge-shaped, unilluminated substrate region 4, which is limited by the angle δ by the substrate underside and in cross-section. It is clearly seen that the unilluminated substrate region 4 in its extent depends on how great the free edge 7 is at the edge of the radiation-generating layer 2. FIG. In addition, the expansion of the unilluminated substrate region 4, also on the refractive index difference between the substrate 1 and the radiation-generating layer 2 depends. On the bottom of the substrate 1, in the area of ​​the unilluminated substrate region 4, the substrate has a base 6, the side surfaces 5 of the substrate 1 are provided in the area of ​​which is substantially perpendicular on the underside of the substrate first

p0058In the area of ​​the pedestal 6 includes the substrate 1 is substantially perpendicular lateral faces 5, which simplify the manufacture of the substrate 1 and improve the yield of the substrate surface. In the example shown in Figure 1, the base 6 has a height h of about 20 microns. The width of the free edge bF is approximately 25 microns. This is a suitable measure to protect the one hand, the radiation-generating layer 2 when separating the substrate 1 from a wafer out. On the other hand this measure is small enough in order to ensure the largest possible availability of the underside of the substrate 1 with radiation-generating layer 2 and favorable electrical properties of the component. Moreover, it is pointed to the thickness D of the substrate, which is 250 microns.

p0059The arrangement shown in Figure 1 is particularly suitable for a good coupling of light from the radiation-generating layer 2, as photons which are radiated from the radiation-generating layer 2 downward can be reflected by the contact layer 17 and coupled out via the substrate 1 , In addition, those photons that are emitted from the radiation-generating layer 2 upward, directly coupled to the substrate 1 and from there to the outside.

p0060Figure 2 shows the results of a "ray tracer" simulation, the output efficiency A, measured in the unit% θ above the angle, measured in degrees, is applied. There are three different measurement curves, wherein the first trace by diamonds, and the second trace by squares and the third measured curve are represented by circles. The first measurement curve with the diamonds associated with a width B of 900 .mu.m. The second curve with the squares belonging to a width B of 1000 microns. The third curve with the circles associated with a width B of 1200 microns. According to Figure 2 optimum output coupling of light for an angle θ of 50 ° reached. Al- lerdings, depending on how large the substrate 1 is, the remaining surface b are very low, which would result in an unfavorable series resistance in the choice of such an angle. From an increased series resistance additional power losses would more than offset the gain in efficiency due to the extraction. Accordingly, the description herein of a semiconductor device, an angle θ to be specified, which is at a width B of 1000 .mu.m and a substrate thickness of 250 microns in the range between 30 ° and 45 °. By taking into account that:

p0061c. + Θ = 90 °

p0062the two angles. and 0, which are side by side used here, at any time be converted into each.

p0063Another advantage of the shown in Figure 1 "upside-down" - assembly, ie the installation of radiation-generating layer at the top, is the compared to the "Up-Side-Up" standard used -Assembly in the forward dishes - th emission characteristic which permits a favorable light extraction from a housing surrounding the substrate, the first

p0064For this purpose, reference is made to Figure 6, seen from the that the substrate 1 may be mounted to the underside or with the contact layer 17 on a lead frame 18, and from which also shows that essentially the top of the substrate 1 for light outcoupling is used.

p0065Figure 3 shows the principle for the arrangement of conductive tracks 10 which by a substantial reduction of the series resistance of the device and a high light transmission the substrate surface can contribute therethrough. A suitable contact is that for example conductor tracks 10 are arranged on top of the substrate first Due to the perpendicular to the crystallographic c-axis (indicated by the displayed vertical downward arrow) existing conductivity and parallel to this better, it comes to a non-isotropic conductivity of the substrate 1. This results in a widening of the through conductor 10 into the substrate 1 the injected electric current, so that so-called. current spreading cone 13 results, which are shown in figure 3, and showing how the expansion of the flow due to the lateral conductivity Dese substrate 1 proceeds. For the example considered here of a substrate 1 made of hexagonal silicon carbide is opening angle γ yields the current expansion cone 13 of 140 °. The distance aL of the conductor tracks 10 from one another will be ideally chosen to simultaneously enter the following conditions at a depth T of the substrate 1:

p00661. The entire cross-sectional area of ​​the substrate 1 is supplied with current, which means that each surface portion of the cross-sectional area in the depth T of the substrate 1 is located in a current spreading cone 13 at least.

p00672. In the depths T overlap adjacent current expansion cones 13 for the first time together.

p0068The terms of this result an optimum for the positioning of the conductor tracks 10, on the one hand an optimum energization of the substrate 1 and on the other hand, a minimum cover the surface of the substrate 1, and hence good optical properties of the component result. In the example shown in Figure 1 may be 50 microns, the distance of the two interconnects aL. The thickness dL of the interconnects 10 may typically be 1 to 1.5 microns, in which case dimensions are, normally present by default in structuring method used here. The ladder- tracks 10 may have any other suitable thickness dimension. The interconnects 10 may be of any suitable electrically conductive material, for example of aluminum or silver.

p0069Figure 4 shows in plan view an arrangement of conductive tracks 10, as it can be carried out for contacting the surface of the substrate 1, which would be in the mentioned example of the n-contact. The conductor tracks 10 are arranged in the shape of squares eleventh The squares 11 have side edges 12, respective side edges 12 of the squares 11 are parallel to each other. It results from an arrangement of the squares 11 with each other, which can be considered analogous to concentric circles. In the center of the squares 11 is a solder pad 16 is arranged, which is adapted to be contacted by a bonding wire electrically. Furthermore, arranged crosswise connecting interconnects 10a are provided which provide for the electrical contacting of the conductor tracks 10 to the soldered surface 16th Solar with 10 can be electrically contacted by contacting the Lδtflache 16 each of the interconnects. Thus can the top of the substrate 1 can be contacted over a large area.

p0070Figure 5 shows another embodiment of a contact-tierungsstruktur for the top of the substrate 1. In Figure 5, the conductor tracks 10 are arranged along three squares 11th Each of these squares 11 having a different width, the side edges 12 of the squares 11 to each other may be arranged equidistantly. This would for example be realized by 11 following dimension applies to the widths BQL, bQ2, BQ3 of squares:

p0071BQL = 220 microns bQ2 = 440 microns BQ3 = 660 microns. By equidistant arrangement of the squares 11, a homogeneous energization be reached the top of the substrate. 1

p0072In Figure 5 is shown yet a further aspect, the

p0073Width of the conductor tracks 10 with increasing square area increases. Accordingly, the width of the innermost conductor BLL 16 microns, the width bL2 the middle interconnect 10 20 .mu.m and the width BL3 the outer conductor 10 27 microns. The dimensions of the widths BLl, BL2, BL3 of the conductor tracks 10 are chosen so that they increase approximately proportional to the corresponding one of the conductor track 10 to be energized area.

p0074The thickness of the conductor tracks 10 shown in Figure 3 is substantially determined by the layer thickness of which is arranged in the middle of soldering surface 11 squares 16, which must have a certain minimum thickness in order to ensure reliable soldering. Since it is advantageous for the interconnects 10, the connecting interconnects 10a and the soldering area 16 apply in one of the process or mask step on top of the substrate 1, it is also advantageous to the interconnects 10, the connecting interconnects 10a and soldering area 16 produce in the same layer thickness. In another possible process, it might also be advantageous for the soldering area 16 thicker perform as the conductor tracks 10 or the connecting conductor tracks 10a, since it is not bonded to the conductor tracks 10, 10a and it can be thus performed also thinner in order to save, for example, material.

p0075Figure 6 shows a substrate 1 on the underside of which a radiation-generating layer 2 is applied. On the underside of the radiation-generating layer 2 an electrical contact layer 17 is also applied. The radiation-generating layer 2 has a sloping side edge 8, which is adapted to light, which is generated in the radiation-generating layer 2 in the substrate 1 and to reflect from there upwards to the desired direction, thus further increasing the light output of the device in an advantageous manner. For the reflection at the slanted side edge 8, it may be advantageous, depending on how the refractive index difference between the radiation-generating layer 2 and the surrounding medium is to exploit a total reflection on this side edge. but it is also possible to move independently of the total reflection a reflective material 9 on the bevelled side edge 8, and thereby cause the reflection of the radiation in the desired direction. In order to prevent an electrical short circuit between the substrate 1 and the contact layer 17, it may be very advantageous, between the reflective material 9, which advantageous ingly silver or aluminum is to apply an electrically insulating layer. This insulating layer may be, for example, silicon nitride.

p0076In the embodiment shown here, it is advantageous the angle ß that the sloping side edge 8 forms with the underside of the substrate 1 between 30 and 60 ° to choose.

p0077Figure 7 shows a substrate 1 during the production of a variety of individual substrates 15, which in turn form the basis of a substrate 1 as shown in FIG. 1 It can be cut into the large substrate 1 V-shaped trenches 14, which is advantageously a V-shaped blade is used. However, the large substrate 1 is not completely sawed through, but there remains a residual thickness dr of the substrate are provided. This residual thickness dr may be following the example of Figure 1, for example 20 microns. Subsequently, the individual substrates can be 15 isolated by breaking or by straight sawing.

p0078The embodiments of the device described according to the figures do not limit the invention described here fertil, but that the invention can be used with any suitable materials that meet the conditions set out run.