Device and method for processing a semiconductor substrate using laser radiation

Abstract

A method for processing a semiconductor substrate, in particular a semiconductor substrate for the production of a photovoltaic solar cell (2), by means of a laser processing step, wherein the semiconductor substrate is locally exposed in a processing area by means of processing laser radiation from a processing laser radiation source (1), and the processing area is exposed by means of processing laser radiation with a wavelength greater than 1000 nm, characterized in that before and / or during the laser processing step the semiconductor substrate is exposed in a conditioning area by means of conditioning laser radiation (3b, 3b') from a conditioning laser radiation source (3, 3') with an illumination intensity greater than 50,000 W / m², wherein by means of the conditioning laser radiation (3b, 3b') a free charge carrier density greater than 1 × 10¹⁶ cm⁻³, in particular greater than 1 × 10¹⁷ cm⁻³, is generated at least in the conditioning area.where the conditioning area at least completely covers the processing area.

Description

[0001] The invention relates to a device and a method for processing a semiconductor substrate according to the preambles of claims 1 and 12.

[0002] For processing a semiconductor substrate, particularly in the production of photovoltaic solar cells, it is known to locally irradiate the semiconductor substrate with laser radiation. This allows for various processing methods: For example, layers and / or sections of the semiconductor substrate can be ablated by the laser radiation. Alternatively or additionally, local melting can lead to the introduction of substances, particularly dopants, and / or electrical contacting. Furthermore, the heat generated by local laser radiation can recrystallize a near-surface area.

[0003] In such processing operations of the semiconductor substrate using local laser radiation, it is always advantageous to be able to specify the energy input within a narrow parameter range in order to avoid undesirable effects, especially damage to the semiconductor substrate, which reduces the electronic quality. Furthermore, short process times are advantageous for achieving cost savings in the manufacturing process.

[0004] The present invention is therefore based on the objective of further developing previously known methods for processing a semiconductor substrate by means of local exposure to laser radiation in order to achieve higher process reliability and / or to enable a reduction in process duration.

[0005] This problem is solved by a method according to claim 1 and by a device according to claim 12. Advantageous embodiments are found in the dependent claims.

[0006] The method according to the invention is advantageously designed for implementation using the device according to the invention, in particular a preferred embodiment thereof. The device according to the invention is preferably designed for implementation using the method according to the invention, in particular an advantageous embodiment thereof.

[0007] The method according to the invention is used for processing a semiconductor substrate. The term "semiconductor substrate" here and in the following refers to a substrate that has at least one semiconductor layer. Such a semiconductor substrate can be a semiconductor wafer, in particular a silicon wafer. Likewise, the semiconductor substrate can consist of a substrate with at least one semiconductor layer, for example, a ceramic substrate coated with a semiconductor layer. Furthermore, the term "semiconductor substrate" encompasses one or more additional layers. These layers can be, in particular, further semiconductor layers, dielectric layers, metallic layers, or combinations thereof.

[0008] For processing in a laser processing step, the semiconductor substrate is locally subjected to processing laser radiation from a processing laser radiation source in a processing area.

[0009] It is essential that, before and / or during the laser processing step, the semiconductor substrate is conditioned in a conditioning area using conditioning laser radiation from a conditioning laser radiation source with an illumination intensity greater than 50,000 W / m². 2 is charged.

[0010] Here and in the following, illumination intensity refers to the intensity of the conditioning radiation at the surface of the semiconductor substrate, which is exposed to the conditioning radiation.

[0011] The invention is based on the understanding that irradiating the semiconductor substrate with conditioning radiation from a separate conditioning laser source in addition to the processing laser source offers significant advantages: The conditioning radiation causes heating and / or an increase in the free charge carrier density, at least in the conditioning zone. In typical processes, it is advantageous that the processing zone in which the semiconductor substrate is treated with the processing laser radiation has an elevated temperature and / or an increased density of free charge carriers. This is achieved by using a separate conditioning laser source with a high intensity greater than 50,000 W / m². 2Since the semiconductor substrate is exposed to the conditioning process, an optimized state of the semiconductor substrate in the processing area can be achieved in a structurally and procedurally simple manner. This results in higher process reliability during the processing of the semiconductor substrate and / or an acceleration of the processing process.

[0012] To achieve rapid conditioning, the semiconductor substrate is preferably heated with an intensity greater than 100,000 W / m². 2 , especially those greater than 200,000 W / m² 2 , preferably greater than 500,000 W / m 2 charged.

[0013] Preferably, the semiconductor substrate is exposed to conditioning laser radiation from the conditioning laser radiation source in the conditioning area for a duration greater than 0.1 s, particularly in the range of 0.01 s to 2 s, especially in the range of 0.1 s to 1 s, prior to the laser processing step, in order to ensure sufficient conditioning at the start of the local laser processing.

[0014] Preferably, the conditioning area completely covers the processing area; in particular, the conditioning area preferably extends beyond the processing area by at least 0.01 cm, preferably at least 0.1 cm, and in particular at least 1 cm. This ensures that the desired process conditions are present in the processing area.

[0015] In typical semiconductor substrate processing by local application of laser radiation, a laser beam from the laser source is moved across the surface of the substrate and / or multiple local areas of the substrate are successively exposed to the laser radiation. It is advantageous for the conditioning area to cover a large region of the semiconductor substrate. In particular, it is advantageous for the conditioning area to extend across the entire width of the semiconductor wafer, preferably with a length of at least 0.01 cm, preferably at least 0.1 cm, and more specifically at least 1 cm, perpendicular to its extension across the width of the semiconductor wafer. This ensures large-area conditioning of the semiconductor substrate.Depending on which areas are being processed using the processing laser radiation, the processing area can be shifted relative to the photovoltaic solar cell to ensure conditioning in the processing area at all times.

[0016] Advantageously, the conditioning area extends over the entire semiconductor substrate. In this advantageous configuration, the semiconductor substrate is thus exposed to the conditioning laser radiation across its entire surface. This ensures conditioning of the entire semiconductor substrate, so that optimized process conditions are always present, regardless of which local areas are treated with the processing laser radiation.

[0017] In an advantageous embodiment, the semiconductor substrate is exposed to processing laser radiation on one side and to conditioning laser radiation on the same side. In this advantageous embodiment, the substrate is thus exposed to both processing and conditioning laser radiation from the same side. This has the advantage that the semiconductor substrate to be processed can be stored as desired, in particular in conveying or holding devices known per se.

[0018] In a further advantageous embodiment, the semiconductor substrate is exposed to the processing laser radiation on one processing side and to the conditioning laser radiation on an opposite conditioning side. In this case, the processing laser radiation on the one hand and the conditioning laser radiation on the other are thus applied from two opposite sides of the semiconductor substrate. This has the particular design advantage that the optical components for imaging the processing laser radiation on the one hand and the conditioning laser radiation on the other can be optimally designed and positioned without the spatial arrangement of the optical means for the processing laser radiation being restricted by the spatial arrangement of the optical means for the conditioning laser radiation.This allows for a homogeneous design and application of the conditioning laser radiation to the semiconductor substrate in a structurally simple manner, in particular a homogeneous application across the entire surface.

[0019] Furthermore, it is particularly advantageous that the semiconductor wafer is arranged on a support that is transparent to the conditioning laser radiation and is exposed to the conditioning laser radiation through the support.

[0020] The method according to the invention is particularly suitable for one or more of the following methods: a. Creating local electrical contacts by local melting using processing laser radiation (hereinafter referred to as “LFC”); b. Creating vias that penetrate the semiconductor wafer (hereinafter referred to as “via”); c. Introduction of dopant by local melting of the semiconductor substrate using processing laser radiation (hereinafter referred to as “doping”); d. Recrystallization of a layer of the semiconductor substrate by at least local melting of the semiconductor substrate using the processing laser radiation (hereinafter referred to as “recrystallization”); e. Creating local structures in thin layers by ablating them using processing laser radiation (hereinafter referred to as “ablation”).

[0021] As already mentioned, the method enables in particular two advantageous conditionings for processing the semiconductor substrate using the processing laser radiation, whereby the two conditionings can be achieved alternatively or together: For a large number of processes, at least heating the semiconductor substrate for processing using the processing laser radiation is advantageous.

[0022] It is generally irrelevant whether the free charge carrier density is additionally increased due to the conditioning radiation or not. It is therefore particularly advantageous to heat the semiconductor substrate, at least in the conditioning region, and preferably the entire semiconductor substrate, to a temperature of at least 50°C, and more preferably at least 100°C, by applying the conditioning radiation. For a multitude of processes, even higher temperatures are advantageous, so that it is advantageous to heat the semiconductor substrate, at least in the conditioning region, and preferably the entire semiconductor substrate, to a temperature of at least 200°C, and more preferably at least 300°C, by applying the conditioning radiation.

[0023] In particular, for the following processing methods, heating to the specified temperatures, at least in the conditioning range, preferably heating the entire semiconductor substrate, and especially heating the entire solar cell, is advantageous: Processing procedures (according to the abbreviations listed above in parentheses) Heating at least the conditioning area, preferably the entire semiconductor substrate, in particular the entire solar cell to LFC at least 200°C, preferably to a temperature in the range of 250°C to 700°C, particularly in the range of 300°C to 600°C, with an intensity preferably greater than 100,000 W / m² 2 , especially those greater than 200,000 W / m² 2 , preferably greater than 500,000 W / m 2 Via at least 400°C, preferably to a temperature in the range of 500°C to 1500°C, particularly in the range of 600°C to 1400°C, with an intensity preferably greater than 100,000 W / m² 2 , especially those greater than 200,000 W / m² 2 , preferably greater than 500,000 W / m 2 Endow at least 400°C, preferably to a temperature in the range of 500°C to 1500°C, particularly in the range of 600°C to 1400°C, with an intensity preferably greater than 100,000 W / m² 2 , especially those greater than 200,000 W / m² 2 , preferably greater than 500,000 W / m 2 Recrystallization at least 400°C, preferably to a temperature in the range of 500°C to 1500°C, particularly in the range of 600°C to 1400°C, with an intensity preferably greater than 100,000 W / m² 2 , especially those greater than 200,000 W / m² 2 , preferably greater than 500,000 W / m 2 ablation at least 400°C, preferably to a temperature in the range of 500°C to 1500°C, particularly in the range of 600°C to 1400°C, with an intensity preferably greater than 100,000 W / m² 2 , especially those greater than 200,000 W / m² 2 , preferably greater than 500,000 W / m 2

[0024] In some processing methods, it is advantageous to increase the free charge carrier density. This is primarily because the absorption of the processing laser in the semiconductor substrate increases if the free charge carrier density is raised by means of conditioning laser radiation. This, in turn, can improve the efficiency of the processing.

[0025] Furthermore, a significant advantage is offered by the fact that, due to increased absorption through increased free charge carrier density using conditioning laser radiation, a more cost-effective processing laser radiation source can be used compared to the processing laser radiation source typically used to date: For typical processing operations, laser radiation sources with a wavelength in the range of 300 nm to 600 nm are used to achieve high processing efficiency. This applies particularly to the following processing methods: ablation and doping. A disadvantage here is that laser radiation sources for laser beams in the aforementioned wavelength range (especially UV lasers) represent costly components of a corresponding processing device. However, if the free charge carrier density is increased due to the conditioning laser radiation, preferably to a free charge carrier density greater than 1 × 10⁻⁶, the efficiency can be significantly reduced. 16 cm –3 , especially larger than 1 × 10 17 cm –3The processing laser radiation source can also be used with processing laser radiation with a wavelength greater than 500 nm, in particular greater than 1000 nm, preferably greater than 2000 nm. Such laser beam sources are more cost-effective (especially IR lasers with a wavelength in the range of 1000 nm to 1200 nm), so that cost savings are possible despite the additional provision of a further conditioning laser radiation source. It is therefore particularly advantageous to achieve a free charge carrier density greater than 1 × 10⁻⁶ by means of the conditioning laser radiation, at least in the conditioning region. 16 cm –3 , especially larger than 1 × 10 17 cm –3 to produce.

[0026] The possibility of cost savings through the use of a different processing laser radiation source is particularly advantageous in the following processing processes: ablation and doping, since a high penetration depth of the laser radiation into the semiconductor substrate can lead to undesirable damage.

[0027] In some processing methods, it is particularly advantageous to increase the free charge carrier density to enhance the absorption of the processing laser radiation as described above, while ensuring that the temperature of the semiconductor substrate does not exceed a predetermined temperature to avoid negative effects on the semiconductor substrate, especially on its electronic quality, due to excessive heating. In a further advantageous embodiment, it is therefore particularly beneficial to actively cool the semiconductor substrate using conditioning laser radiation during and / or before its application (especially advantageously at least during the application of the processing laser radiation). This active cooling ensures that the semiconductor substrate does not exceed a predetermined upper temperature limit.Active cooling can be achieved by blowing on the semiconductor substrate with a cooling gas or ambient air, preferably cooled ambient air. Cooling can also be achieved by spraying and / or wetting the semiconductor substrate with a cooling fluid. Alternatively, active cooling can be achieved through indirect or, preferably, direct thermal contact between the solar cell and a cooling block that is actively cooled. Such a cooling block can be designed, in a manner known per se, for the photovoltaic solar cell to be laid flat on the cooling block and, particularly preferably, for the solar cell to be drawn against the cooling block to ensure good thermal contact between the solar cell and the cooling block. The cooling block can itself have active cooling or be actively cooled by the flow of a cooling medium, in particular a cooling fluid.

[0028] Processing operations in which, advantageously, active cooling of the photovoltaic solar cell takes place at least during the application of the conditioning laser radiation to the semiconductor substrate are particularly LFC.

[0029] To achieve increased absorption of the processing laser radiation in the semiconductor substrate, a free charge carrier density of at least 1 × 10 is preferably achieved in the semiconductor substrate, at least in the conditioning area, preferably in the entire semiconductor substrate, by means of the conditioning laser radiation. 16 cm –3 , in particular at least 1 × 10 17 cm –3 This results in increased absorption of the processing laser radiation. It is particularly advantageous to use processing laser radiation with a wavelength greater than 1000 nm, especially greater than 2000 nm, to achieve this. In this case, a combination with a charge carrier density of at least 1 × 10⁻⁶ is particularly beneficial. 16 cm–3 in combination with processing laser radiation with a wavelength greater than 2000 nm or a combination of a charge carrier density of at least 1 × 10 17 cm –3 advantageous in combination with processing laser radiation with a wavelength greater than 1000 nm.

[0030] The conditioning laser radiation preferably lies in a wavelength range of 400 nm to 1200 nm. If only heating of the semiconductor substrate is desired, but not or only a slight increase in the free charge carrier density, a conditioning laser radiation source with a wavelength range that is not absorbed or only slightly absorbed by the semiconductor substrate can be selected. In this case, the wavelength range of the processing laser radiation source preferably lies in the range of 900 to 1200 nm.Alternatively and / or additionally, if the semiconductor substrate has a layer that absorbs the conditioning laser radiation, such as a metallized back in typical solar cells, it is possible to apply conditioning laser radiation to the photovoltaic solar cell from the side of the aforementioned absorbing layer opposite the semiconductor substrate, so that the conditioning laser radiation is completely or at least substantially absorbed by the layer that absorbs the conditioning laser radiation (in particular a metallic layer), and thus the photovoltaic solar cell is essentially heated and no or only minimal free charge carriers are generated by absorption of the conditioning laser radiation.

[0031] The present invention is further solved by a device according to claim 12. Advantageous embodiments are found in the dependent claims.

[0032] The device according to the invention for processing a semiconductor substrate using a laser, in particular for manufacturing a photovoltaic solar cell, comprises a processing laser radiation source for locally irradiating the semiconductor substrate with processing laser radiation. With regard to this basic structure, the device can be designed in a manner known per se. In particular, it is within the scope of the invention that the device includes means for relative movement between the photovoltaic solar cell and the processing laser radiation. Such means can be mechanical means for moving the photovoltaic solar cell and / or optical means for focusing the processing laser radiation onto a desired processing location on the photovoltaic solar cell, in particular movable and / or rotatable and / or tiltable deflecting mirrors in the beam path of the processing laser radiation.

[0033] It is essential that the device, in addition to the processing laser radiation source, has a conditioning laser radiation source for imparting conditioning laser radiation to the semiconductor substrate at an illumination intensity greater than 50,000 W / m². 2 .

[0034] This results in the advantages already listed in the procedures and in particular in claim 1.

[0035] The conditioning laser radiation source is preferably configured as a diode laser, in particular as an array comprising a plurality of diode lasers. Diode lasers offer the advantage of a space-saving design compared to other laser sources. Furthermore, they can be easily controlled via the appropriate electrical power input, allowing the conditioning laser radiation to be switched on and off, particularly at high clock rates, and / or adjusted during the process. The use of a plurality of lasers, especially a plurality of diode lasers, offers the advantage of enabling simple and cost-effective illumination of a conditioning area, particularly the entire photovoltaic solar cell. Preferably, a plurality of laser diodes are arranged as an array, in particular with at least two columns and at least one row.

[0036] The conditioning laser radiation source preferably has a wavelength in the range of 400 nm to 1200 nm, particularly in the range of 600 nm to 900 nm, thereby providing the aforementioned advantages, whereby, depending on the application, the wavelength ranges mentioned as advantageous in the method are also advantageously ensured by a corresponding design of the conditioning laser radiation source.

[0037] As previously explained, active cooling is advantageous to prevent excessive heating of the photovoltaic solar cell, at least during exposure to conditioning laser radiation. Therefore, the device preferably incorporates active cooling for the semiconductor substrate. This can be configured as described above.

[0038] In particular, it is advantageous that the device has a holder for the semiconductor substrate and that the holder is actively cooled in order to effect active cooling of the photovoltaic solar cell by means of thermal contact between the holder and the photovoltaic solar cell.

[0039] In a further advantageous embodiment, the device has a holder for the semiconductor substrate, which is transparent to the conditioning laser radiation. The holder is positioned in the beam path of the conditioning laser radiation between the conditioning laser source and the semiconductor substrate. This allows the photovoltaic solar cell to be irradiated with conditioning laser radiation through the holder. The advantage of this is that processing from the side of the semiconductor substrate opposite the holder is possible without requiring components of the conditioning laser source or optical means for imaging the conditioning laser radiation to be located in the beam path between the processing laser source and the photovoltaic solar cell.

[0040] Further preferred features and embodiments are described below with reference to exemplary embodiments and the figures. These show:

[0041] Fig. 1 a first embodiment of a device according to the invention, in which the processing laser radiation source and the conditioning laser radiation source are arranged on the same side of a photovoltaic solar cell to be processed and

[0042] Fig. 2 a second embodiment in which the conditioning laser radiation source and the processing laser radiation source are arranged on opposite sides of the solar cell.

[0043] The figures are schematic representations, not to scale. Within the figures, identical reference symbols denote identical or equivalent elements.

[0044] Fig.Figure 1 shows a first embodiment of a device according to the invention for processing a semiconductor substrate using a laser.

[0045] The device includes a processing laser radiation source. 1 which is designed as a pulsed IR laser. With such a laser, it is particularly advantageous to generate point contacts using the LFC method known per se, as described, for example, in DE 100 46 170 A1.

[0046] The processing laser radiation source 1 is a processing deflection unit 1a assigned, which are used to deflect a beam by means of the processing laser radiation source 1 generated laser beam on any point of a solar cell to be processed 2 It serves this purpose. An example is a processing laser beam. 1b depicted, which refers to one of a multitude of successively processed points on the front of the solar cell. 2encounters.

[0047] The processing laser radiation source generates laser radiation with a wavelength of 1030 nm.

[0048] It is essential that the in Fig. 1. The device shown additionally includes a conditioning laser radiation source. 3 It features a diode laser. The conditioning laser radiation source 3 Can optics be used as an optical means? 3a to be assigned to a front side of the photovoltaic solar cell 2 Surface and homogeneous with conditioning laser radiation 3b to impose.

[0049] Conditioning laser radiation source 3 and the optical lens 3a are designed to interact in such a way that on the surface of the solar cell 2 the conditioning laser radiation with an illumination intensity of approximately 100,000 W / m² 2This results in excess charge carriers in the solar cell. 2 Energy is generated, and in addition, the solar cell is heated to a temperature of about 350°C.

[0050] The solar cell 2 is on a bracket 4 the device. In this case, there is only minimal heat conduction between the solar cell. 2 and bracket 4 desired, since the conditioning laser radiation 3b in particular a warming of the solar cell 2 This is to be done. The bracket indicates this. 4 Retaining pins on which the solar cell 2 rests on the back side, so that only one surface faces the rear of the solar cell. 2 comparatively small contact area between solar cell 2 and bracket 4 and a correspondingly comparatively low thermal contact exists.

[0051] In an alternative embodiment, the holder 4 be made of a thermally insulating material and / or on the solar cell 2 The side facing the surface should be coated with a thermally insulating layer.

[0052] With a device according to Fig. 1 In particular, the following preferred embodiments of a method according to the invention can be carried out: a. Creation of local electrical contacts by local melting using processing laser radiation (wavelength 1000 nm to 1200 nm). An increased semiconductor substrate temperature due to the conditioning laser (wavelength of 700 nm to 900 nm) increases the melting efficiency, and slower cooling of the melt after processing increases crystallinity and improves the formation of local high doping in the contact area. b. Creation of holes, so-called vias, that penetrate the semiconductor wafer using a pulsed IR laser (wavelength 1000 nm to 1200 nm). Conditioning radiation with a wavelength of 700 to 900 nm leads to an increase in the wafer temperature. This increases the material removal rate and thus the drilling efficiency. The increased semiconductor substrate temperature also reduces recrystallization damage at the edges of the vias due to a slower cooling rate. c. Dopant introduction by locally melting the semiconductor substrate using processing laser radiation (wavelength 500 nm to 1200 nm). Conditioning radiation with a wavelength of 700 to 900 nm leads to an increase in the wafer temperature. The increased temperature improves the diffusion of the dopant within the semiconductor substrate, and any damage to the material can recrystallize due to slower cooling ramps. d. Recrystallization with a pulsed laser (wavelength 500 nm to 1200 nm) by melting. An increased semiconductor substrate temperature due to the conditioning laser (wavelength of 700 nm to 900 nm) increases the melting efficiency, and the crystallinity is increased by slower cooling of the melt after processing.

[0053] In Fig. Figure 2 shows a second embodiment of a device according to the invention.

[0054] This device also features a processing laser radiation source. 1 and a processing deflection unit 1a up to a processing laser beam 1b successively to several predetermined locations on the front side of a solar cell 2 to depict.

[0055] In contrast to the device according to Fig. 1 is a conditioning laser radiation source 3' on the processing laser radiation source 1opposite side of the solar cell 2 arranged.

[0056] The conditioning laser radiation source 3' It is designed as an array of semiconductor diode lasers such that the semiconductor lasers are arranged at the intersection points of a rectangular grid with square grid elements. Viewed from above, the array has an area of ​​approximately 15 × 15 cm. 2 This results in a comparatively homogeneous, planar conditioning laser radiation. 3b' generated by the majority of semiconductor laser diodes.

[0057] The solar cell 2 is mounted on a holder transparent to the conditioning laser radiation – with a wavelength of 808 nm 4' arranged so that the conditioning laser radiation reaches the holder 4' penetrates and backs onto the solar cell 2 encounters.

[0058] The solar cell 2At this stage of the process, the back already has a full or nearly full-surface metallization, so that the conditioning laser radiation 3b' not or only to a limited extent in a semiconductor solar cell 2 penetrates and thus essentially causes heating of the solar cell 2 This occurs and no or only a minor generation of free charge carriers in the solar cell. 2 due to absorption of the conditioning laser radiation 3b' in the semiconductor substrate of the solar cell 2 This has been done.

[0059] In an alternative embodiment, the device according to Fig. 1. An actively cooled bracket 4 on which the solar cell 2 rests flat on the back side, ensuring good thermal contact between the solar cell and the surface. 2 and bracket 4 consists of the bracket. 4It features lines for a coolant that is supplied cooled by an external cooling unit. The bracket 4 It is essentially made of metal, especially copper, and therefore has a large thermal mass and high thermal conductivity.

[0060] In this alternative embodiment of the first embodiment, active cooling can thus ensure that the solar cell 2 during exposure to conditioning laser radiation 3b does not heat up above a predetermined temperature.

[0061] In the previously mentioned LFC process, this is advantageous because a temperature above 450°C for several seconds can lead to a deterioration of the front-side contact (silver paste). QUOTES INCLUDED IN THE DESCRIPTION

[0062] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0063] DE 10046170 A1

[0045]

Claims

[1] Method for processing a semiconductor substrate, in particular a semiconductor substrate for the production of a photovoltaic solar cell ( 2 ), with a laser processing step, wherein the semiconductor substrate is locally subjected to processing laser radiation from a processing laser radiation source in a processing area, characterized by that before and / or during the laser processing step the semiconductor substrate is conditioned in a conditioning area using conditioning laser radiation ( 3b , 3b' ) a conditioning laser radiation source ( 3 , 3' ) with an illuminance greater than 50,000 W / m² 2 is charged. [2] Method according to claim 1, characterized by that the conditioning area at least completely covers the processing area, in particular extending beyond it by at least 0.5 cm, preferably at least 1 cm, all around. [3] Method according to any of the preceding claims, characterized by that the conditioning area extends over the entire width of the semiconductor wafer, preferably that the conditioning area has a length of at least 0.01 cm, preferably at least 0.1 cm, and in particular at least 1 cm, transverse to its extension over the width of the semiconductor wafer. [4] Method according to any of the preceding claims, characterized by that the conditioning area is moved across the surface of the semiconductor wafer. [5] Method according to any of the preceding claims, characterized by that the conditioning area extends over the entire semiconductor wafer. [6] Method according to any of the preceding claims, characterized by that the semiconductor substrate is conditioned in the conditioning area using conditioning laser radiation before the laser processing step ( 3b , 3b' ) the conditioning laser radiation source (3 , 3' ) for a duration in the range of 0.01 s to 2 s, in particular in the range of 0.1 s to 1 s. [7] Method according to any of the preceding claims, characterized by that before and / or during the laser processing step, the semiconductor substrate, at least in the conditioning area, preferably the entire semiconductor substrate, is heated by means of the conditioning laser radiation to a temperature of at least 50°C, in particular at least 100°C, preferably to a temperature of at least 200°C, in particular at least 300°C. [8] Method according to any of the preceding claims, characterized by that the semiconductor substrate is exposed to the processing laser radiation on one processing side and to the conditioning laser radiation on an opposite conditioning side ( 3b , 3b' ) is charged. [9] Method according to any of the preceding claims, characterized bythat the semiconductor wafer is on a surface suitable for conditioning laser radiation ( 3b , 3b' ) transparent layer is arranged and the conditioning laser radiation passes through the layer ( 3b , 3b' ) is charged. [10] Method according to any of the preceding claims, characterized by that the laser processing step includes one or more of the following processing steps: a. Creating local electrical contacts by local melting using processing laser radiation; b. Creating vias that penetrate the semiconductor wafer; c. Introduction of dopant by local melting of the semiconductor substrate using processing laser radiation; d. Recrystallization of a layer of the semiconductor substrate by at least local melting of the semiconductor substrate using the processing laser radiation; e. Creating local structures in thin layers by ablating them using processing laser radiation (ablation). [11] Method according to any of the preceding claims, characterized by that during and / or before the semiconductor substrate is exposed to the conditioning laser radiation ( 3b , 3b' ) active cooling of the semiconductor substrate takes place. [12] Device for processing a semiconductor substrate using a laser, in particular for manufacturing a photovoltaic solar cell ( 2 ), with a processing laser radiation source ( 1 ), for locally applying processing laser radiation to the semiconductor substrate, characterized by that the device includes, in addition to the processing laser radiation source, a conditioning laser radiation source ( 3 , 3') exhibits, for applying conditioning laser radiation to the semiconductor substrate ( 3b , 3b' ) a lighting intensity greater than 50,000 W / m² 2 . [13] Device according to claim 12, characterized by that the conditioning laser radiation source ( 3 , 3' ) is configured as a diode laser, in particular as an array comprising a plurality of diode lasers. [14] Device according to any one of the preceding claims 12 to 13, characterized by that the device has a holder ( 4 , 4' ) for the semiconductor substrate, which is used for the conditioning laser radiation ( 3b , 3b' ) is transparent and that the holder ( 4 , 4' ) in the beam path of the conditioning laser radiation ( 3b , 3b' ) between conditioning laser radiation source ( 3 , 3') and semiconductor substrate. [15] Device according to any one of the preceding claims 12 to 14, characterized by that the device has active cooling for actively cooling the semiconductor substrate.