WO2019145486A9

WO2019145486A9 - Method and device for cleaning etched surfaces of a semiconductor substrate

Info

Publication number: WO2019145486A9
Application number: PCT/EP2019/051875
Authority: WO
Inventors: Maher Izaaryene; Mirza CORDA; Bianca WATTENBERG; Martin Max MENSCHICK; Benjamin MANDLMEIER; Jens Eckstein
Original assignee: Singulus Technologies Ag
Priority date: 2018-01-26
Filing date: 2019-01-25
Publication date: 2019-09-19
Also published as: WO2019145486A1; DE102018206980A1

Abstract

The invention relates to a method which comprises the cleaning of the surface of a textured silicon substrate and causes a removal of organic compounds located on the surface of the textured silicon substrate, and further comprises a removal of porous silicon from the surface of the textured silicon substrate and carrying out a metal cleaning of the surface of the textured silicon substrate.

Description

Method and apparatus for cleaning etched surfaces of a semiconductor substrate

description

The present invention relates to a method and apparatus for treating a surface of a textured silicon substrate. More particularly, the present invention relates to a method for cleaning etched surfaces of a semiconductor substrate, such as is applicable to photovoltaic modules. Exemplary embodiments relate to a process for the post-purification of multicrystalline diamant wire-sawn silicon substrates. Treatment of a textured silicon substrate may involve cleaning thereof, which may be done using, for example, an ozone-containing medium.

Semiconductor substrates can be textured during their further processing, which means that the surface of the semiconductor substrate can be treated, for instance to perform a roughening process. Texturing can be obtained, for example, by means of an acidic texture in the inline process. These are described, for example, in US 2010/0055398 A1 or EP 2 232 526 B1.

An apparatus and a method for the asymmetric alkaline texture of surfaces is described in DE 10 2013 218 693 A1.

A texture can also be obtained by acid etching, as described for example in US 2015/0040983 A1.

Diamond wire sawn multicrystalline wafers can also be textured.

Texturing can also be achieved with acidic media using additive or organic compounds. For this purpose, an etching mixture can be used to produce a textured surface on silicon substrates. Such an etching mixture may comprise at least one polymer. Specifically, a polymer which is resistant to nitric acid and hydrofluoric acid and / or a hydrophilic polymer may be used. Such a polymer used as thickener may be selected from the group consisting of cellulose, in particular methyl cellulose, polyvinyl alcohol and polyethylene oxide can be selected. In CN 103132079 A additives are described which consist of polyvinyl alcohol and polyethylene glycol alcohol.

A conventional method will be explained in more detail with reference to FIG.

FIG. 11 shows a schematic flow diagram of a method 1000 according to the prior art. Step 1010 includes etching the semiconductor substrate to texure it. In a subsequent step 1020, the semiconductor substrate is rinsed in order to remove residues of substances or materials which have come into contact with the semiconductor substrate in step 1010. In a step 1030, an alkaline post-cleaning of the semiconductor substrate takes place. Thereafter, step 1020 is executed again to rinse the semiconductor substrate. In a step 1040, an acid subsequent cleaning of the semiconductor substrate takes place. Thereafter, purging 1020 is again performed to clean the semiconductor substrate of acid post-cleaning residues 1040. In a step 1050, the semiconductor substrate is dried.

A disadvantage of this method is that impurities can remain on the semiconductor substrate.

Accordingly, it would be desirable to have methods and apparatus for treating semiconductor substrates that enable effective cleaning.

The object of the present invention is therefore to provide a method for treating a surface of a textured silicon substrate and an apparatus for carrying out such a method, which provide high-quality cleaned semiconductor substrates.

This object is solved by the subject matter of the independent patent claims.

A finding of the present invention is that it has been recognized that, although some residues of the etching, in particular porous silicon and metal impurities, can be eliminated by the alkaline post-cleaning and the acid subsequent cleaning, other impurities remain. In methods according to embodiments, therefore, cleaning of the surface of the textured silicon substrate to remove organic compounds is performed. The organic ones Compounds are located on the surface of the textured silicon substrate and may be, for example, residues of the etching process and / or the contact of the semiconductor substrate with other substances and / or persons. By cleaning the surface of the organic compounds, a highly clean textured surface is obtained which can be used for high quality processed products, such as solar cells. Cleaning is understood to be cleaning by removal of substances to be removed.

Examples provide a method of treating a surface of a textured silicon substrate. The method includes cleaning the surface of the textured silicon substrate to effect removal of organic compounds that are on the surface of the textured silicon substrate. The method includes removing porous silicon at the surface of the textured silicon substrate. The method further includes performing a metal cleaning of the surface of the textured silicon substrate.

Examples provide an apparatus for carrying out such a method. Such apparatus includes process media supply means for providing media for cleaning, alkaline post-cleaning, and acid post-cleaning of the surface, and includes substrate handling means for positioning the silicon substrate to treat the surface.

Cleaning for removal of organic compounds makes it possible to obtain a pure surface and therefore high-quality products.

Examples of the disclosure will be explained in more detail below with reference to the accompanying drawings. Show it:

FIG. 1a is a schematic flowchart of a method according to an embodiment; FIG.

FIG. 1 b is a schematic flow diagram of a method according to an embodiment, in which a cleaning of a surface of a textured silicon substrate takes place; FIG. FIG. 2 is a schematic flow diagram of a method according to an embodiment, which comprises an optional etching step, optional rinsing steps and an optional drying step; FIG.

3 is a schematic flowchart of a method according to an embodiment, which includes removal of porous silicon and / or metal;

4 is a schematic flow diagram of a method according to an embodiment comprising an alkaline post-purification;

FIG. 5 is a flowchart of a prior art RCA cleaning; FIG.

Fig. 6 is a schematic flow diagram of a prior art process used to remove the porous silicon and perform metal cleaning;

7 is a schematic flowchart of a method according to an embodiment having an ozone-based treatment;

FIG. 8 is a schematic illustration of one for performing a method according to the present disclosure; FIG.

Fig. 9 is a schematic representation of an alternative example of a device for

Performing a method according to the present disclosure, wherein a substrate handling device is implemented as a horizontal transport system with rollers;

Fig. 10 is a schematic representation of an alternative example of a device for

Performing a method according to the present disclosure, wherein a process media provider comprises a process media pool; and

11 is a schematic flow diagram of a method 1000 according to the prior art.

Hereinafter, examples of the present invention will be described in detail and using the attached drawings. In the following description will be Many details are described to provide a more thorough explanation of examples of the disclosure. However, it will be apparent to those skilled in the art that other examples may be implemented without these specific details. The characteristics of the different examples can be combined with one another, unless features of a corresponding combination are mutually exclusive or such a combination is expressly excluded. In the following, the same reference numerals are used for elements having the same or a similar function, so that even without a detailed embodiment, the description of these elements is interchangeable.

FIG. 1 a shows a schematic flow diagram of a method 100 according to an exemplary embodiment. The method 100 includes a step 110. The step 110 includes cleaning the surface of the textured silicon substrate to effect removal of organic compounds that are on the surface of the textured silicon substrate. The step 110 further includes removing porous silicon at the surface of the textured silicon substrate and performing metal cleaning of the surface of the textured silicon substrate.

As will be explained in more detail below, the cleaning, the removal of porous silicon and the execution of the metal cleaning can also take place in at least partially separate steps, while otherwise stated, at least two of the three purification steps can be carried out in a common step, or As shown in FIG. 1 a, all three cleaning steps can be carried out in a common step 110.

One embodiment of the cleaning steps of removal of porous silicon, metal cleaning and removal of organic compounds in one step can be understood to mean that a corresponding purification step, in particular an isolated and specially arranged cleaning step, for example in a separate process media pool or a separate Section of a system, during the process is not carried out again, in particular not subsequently, at least as long as no further processing of the substrate takes place, which leads to new impurities, which may require a re-cleaning. This means that the arrangement of corresponding device sections can be dispensed with.

1 b shows a schematic flow diagram of a method 150 according to an exemplary embodiment, in which, in a step 160, the cleaning of the surface of the textured silicon substrate to effect removal of organic compounds present on the surface of the textured silicon substrate. In a step 170 of the method 150, the removal of porous silicon takes place on the surface of the textured silicon substrate. In a step 180 of the method 150, a metal cleaning of the surface of the textured silicon substrate is carried out. An order of steps 160, 170 and 180 is arbitrary. Prior to and / or after any one of steps 160, 170, and / or 180, rinsing of the silicon substrate may be accomplished, for example, by performing step 1020. Collectively, steps 160, 170, and 180 provide step 110 of method 100.

The following explains how the individual steps 1 10 or 160, 170 and 180 can be carried out. The cleaning in the step 1 10 and / or 160 for removing the organic compounds may be wholly or partly by contacting the silicon substrate with an oxidative component. Exemplary oxidative components are, for example, hydrogen peroxide (H2O2) or ozone (O3). Alternatively or additionally, the silicon substrate may also be associated with an alkaline component, for example potassium hydroxide (KOH). Alternatively or additionally, a RCA (Radio Cooperation of America) cleaning can be carried out, which includes a wet chemical cleaning process. RCA cleaning may include cleaning the semiconductor substrate in two baths. A first bath may include an aqueous solution of ammonium hydroxide and hydrogen peroxide. A second bath into which the semiconductor substrate is subsequently added may include an aqueous solution of hydrochloric acid and hydrogen peroxide. The cleaning can be carried out at room temperature, but can also be carried out in other temperature ranges. By using a slightly higher temperature range, for example, in a range between 40 ° C and 70 ° C, a high purification efficiency can be obtained. This means that the cleaning can take place in a bath, for example in a so-called batch process. The method may also include a plurality of baths into which the respective semiconductor substrate is successively brought. Alternatively, at least one bath can be replaced by wetting with the liquid to be applied, for example by using spray nozzles.

Removal 170 of porous silicon at the surface of the textured silicon substrate or the corresponding substep in step 1 10 may be accomplished by alkaline post-cleaning and / or by treatment with ozone. The performing 180 of the metal cleaning of the surface of the textured silicon substrate or the corresponding sub-step in the step 1 10 may be carried out by an acid post-cleaning and / or by the treatment with ozone. The metal cleaning 180 and / or the corresponding partial step in the step 1 10 can also be obtained by contacting the semiconductor substrate to be cleaned with an aqueous solution comprising water and at least one of hydrogen chloride (HCl) and hydrofluoric acid (HF). Alternatively or additionally, a solution comprising hydrofluoric acid, hydrogen chloride and ozone can also be used.

In particular, in the step 1 10 but also in the method 150, an order of alkaline and acid purification is arbitrary. That is, unlike in FIG. 1 b, step 180 may be executed first and then step 170 may be executed. An order is also arbitrary with regard to step 160, that is, step 160 may be executed before or after step 170 and / or before or after step 180. The alkaline post-purification can be obtained, for example, by carrying out the step 1030. The acid post-purification can be carried out, for example, by carrying out step 1040.

Alternatively, to obtain the purification of all three components, the organic compounds, the porous silicon and the metal impurities, ozone can also be used. By using ozone, it becomes possible to combine steps 160 or 170 and / or 180 together to perform at least two of steps 160, 170 and 180 in a common step. According to an exemplary embodiment, this can also be carried out such that the steps 160, 170 and 180 are performed together in the step 110. That is, the cleaning in step 160 and / or 110 may also effect removal of porous silicon (step 170) and / or texture additives, and / or metals (step 180).

The use of ozone in steps 160, 170 and / or 180 may also be understood as ozone-based treatment of the surface of the textured silicon substrate. An exemplary ozone concentration for such a step may range from 1 ppm to 150 ppm, from 5 to 150 ppm, or from at least 10 to 150 ppm. Exemplary embodiments also apply without restriction to lower limits of more than 30 ppm, about 31 ppm or more, 35 ppm or more, 40 ppm or more or even 100 ppm or more with simultaneous use of the said upper limits. Referring to both method 150 of FIG. 1 b and method 100 of FIG. 1 a, preferred embodiments of methods 100 and 150 will be discussed. Regardless of whether cleaning is done in three steps, reduced to two steps, or together in one step, a combination of ozone with hydrofluoric acid (HF) and / or HCl may be used in addition to oxidative removal of organic materials by ozone, ie, ozone the organic compounds can be removed by a removing mechanism simultaneously organic residues can be removed by the impurities or residues are removed by the substrate or the substrate is etched. For this purpose, embodiments provide for using a concentration of at most 1% HF and / or HCl. For example. removes the HF silicon oxide and by removing the oxide layer also adhering to the surface organic impurities or their degradation products are replaced.

By adding HCl, the combination HF / HCl and ozone can be additionally removed metal impurities.

The HF concentration is kept within the scope of the described embodiments at most 1, 5% or at most 1%, preferably between 0.05% and 0.5%.

The HCI concentration is maintained in the described embodiments at most 1, 5% or at most 1%, preferably between 0.05% and 0.5%.

To achieve the desired results, short treatment times, which may be shorter than 5 minutes, preferably between 0.5 minutes and 3.5 minutes, are sufficient.

The solution may preferably have a pH in a range of at least 0 and at most 7 and be used at a process temperature of at least 5 ° C and at most 80 ° C. Preference is given to temperatures of at least 20 ° C and at most 65 ° C or at least 50 ° C and at most 65 ° C. The solution is preferably heated to temperatures above room temperature, namely taking into account the upper limit of 80 ° C, 65 ° C or 50 ° C to temperatures of at least 30 ° C, at least 35 ° C or at least 40 ° C, since with increasing temperature, the solubility of organic compounds / residues is improved and thus small or short Aufnahmestre- bridges for the introduction of ozone in the solution and / or high ozone concentrations are allowed. Increased temperatures are thus available at a high degree of contamination with metal contamination and / or short treatment times. According to embodiments, a high ozone concentration up to about 150 ppm may be used or even exceed it. As the ozone concentration increases, embodiments provide for reducing the temperature from the described 23 ° C to obtain good ozone solubility in the medium.

FIG. 2 shows a schematic flow diagram of a method 200 according to an exemplary embodiment. The method 200 includes a plurality of optional steps, including an optional step 210, in which etching of the semiconductor substrate occurs, such as to obtain texturing of at least one surface of the semiconductor substrate. During etching, organic contaminants may form. One reason for this is that used texture additives may contain organic compounds and may remain on the surface during or after the etching step.

One or more targets of the etch 210 and / or a major focus thereof may be on an acidic isotropic texture provided with an additive to treat multicrystalline diamond wire sawn silicon substrates. The additive may be organic or inorganic. An additive used may comprise as a component a polymer. The etching 210 may be performed in various ways. One type is, for example, a metal-assisted chemical etching using metal particles. This can also be described by the English technical term "Metai Assisted Chemical Etching (MACE)". It can also be an acid isotropic texture, d. h., Mixture be used. Such an acid isotropic texture with organic and / or inorganic additives may be, for example, a combination of hydrofluoric acid, nitric acid (HNO3) and at least one additive. Optionally, water can also be added so that the acid isotropic texture with additive can also be a combination of hydrofluoric acid, nitric acid, water and the additive. As described in DE 10 2016 210 883 A1, in the etching solution, with a small proportion of at most a few% by weight, an additive from the group consisting of alcohol, surfactant, glycol can be contained. By etching 110. By etching 210, etch rates and the appearance of the semiconductor substrate surface can be adjusted depending on the temperature and / or time.

Typically, temperature ranges in the range of 10 ° C to 30 ° C and etches in the range of 0.5 minutes to 10 minutes can be used. Additive and / or additive residues may adhere to the surface and alter the wetting behavior for further steps and / or inhibit the attack of further etchants, ie inhibit. The additive may have one or more components and thus also be understood as an additive or a combination of several additives. The use of several additives may be such that the combination of the additives only work together in a solution or in the bath used, which means that, when the additives are combined in themselves, no interaction takes place yet. The detachment of impurities on the wafer, such as metals and / or metal ions, can also be inhibited.

Alternatively or additionally, an electrochemical etching can also be carried out. Further examples for use during the etching process include, for example, a chemical edge isolation, a smoothing of the surface, i. h., performing a polish, selective emitter removal, removal of sawing damage, especially in diamond-sawn silicon substrates, single-side treatment (single-sided treatment), or treatment of both major sides (double-sided treatment). That is, the use of an acidic isotropic texture can optionally be done using an additive, which additive may be organic or inorganic. In one example, the etch may be done without additive.

The etch 210 may result in residues on at least one of the surfaces of the semiconductor substrate. These residues may be porous silicon, may alternatively or additionally include metal contaminants, but may alternatively or additionally include organic contaminants. For removal, in particular of the additive components, an optional step 220 may be carried out, in which a rinsing of the semiconductor substrate takes place. The purging 220 or the removal of the additive components can take place in at least one step and / or one pass. This means that it can also be flushed more often. The purging 220 may include contacting the semiconductor substrate with water, that is, a medium of the purging operation 220 may be water. Alternatively or additionally, ozone, hydrofluoric acid, hydrogen chloride and / or other agents may also be used. The rinsing process 220 can take place in a temperature range of, for example, at least 5 ° C. and at most 90 ° C., for example in order to avoid the boiling of water. For example, a rinsing process, which can be referred to by the technical term "Quick Dump Rinse", can be used. Overflow rinse and / or cascade rinse aid can be used. For example, a purging process may involve a fixed consumption of purging medium, advantageously, the purging process may be dynamically adjusted to the degree of contamination of the wafer and / or the purging medium. Step 220 may be performed, in particular, if the method includes step 210.

As an alternative to step 210, a pre-etched semiconductor substrate may also be provided for cleaning and / or removing porous silicon and / or metal.

In both cases, in a step 230 of the method 200, a cleaning of organic compounds from the semiconductor substrate, such as that resulting from step 210, takes place. This can be done, for example, in the context of step 110 and / or step 160. At the same time this can lead to metal contamination.

The method 200 further comprises an optional step 240, in which a rinsing of the semiconductor substrate can take place, in particular if the cleaning 230 and the removal of the porous silicon and / or the execution of the metal cleaning takes place in at least two steps.

The method 200 includes a step 250 in which the removal of porous silicon and / or metal is accomplished by an ozone-based treatment. Here, for example, the metal impurities occurring in step 230 can be removed. In this case, for example, steps 170 and 180 are combined, using the ozone-based treatment for the combination. In particular, using the ozone-based treatment in step 250, steps 230 and 250 may also be performed in common, i. H. at the same time, so that the step 240 can be omitted without restriction, since the cleaning of the organic compounds, the removal of the porous silicon and / or the metal cleaning takes place at the same time.

It can be seen that the mutual generation of new impurities by carrying out the purification steps 210 and 230 offers the potential for improvement in the fact that these newly generated impurities are immediately removed or prevented in the same step. This allows a small dimension of the corresponding plant to be obtained, for example if a common pool, bath or common treatment area is used for all three purification steps. The method may be adapted based on different adjustment parameters and / or materials used such that the ozone-based treatment is configured to effect one or more of the alkaline post-cleaning, the removal of porous silicon, the metal cleaning, and the removal of organic compounds. For example. For example, adding components, constituents or additives to the cleaning medium can cause different settings. According to one embodiment, all three cleaning steps can be obtained in a common pool under at least approximately constant conditions. Purification of organic contaminants can be carried out particularly effectively at higher temperatures and higher ozone concentrations and, taken alone, can also be carried out only with ozone and water. An additional removal of porous silicon can be obtained by adding hydrofluoric acid. It is known to perform a metal cleaning only with HF / HCl. Use of a combination of hydrofluoric acid, hydrogen chloride and ozone and / or a combination of hydrofluoric acid and ozone allows all three steps to be carried out simultaneously, removal of organic compounds, metal residues and porous silicon.

Subsequent thereto, in an optional step 260, a renewed rinsing process can be carried out. Subsequently, the method 200 comprises a step 270, in which a drying of the semiconductor substrate takes place. Step 270 may be after cleaning. The drying can be carried out in a temperature range of at least 0 ° C, d. h., A state in which water is liquid, to allow evaporation of the raw material water. A temperature range of at least 25 ° C and at most 100 ° C is preferred. The temperature may be constant or variable over a course of step 270. For example, a variable temperature profile with increasing temperature can help to minimize material stress in the semiconductor substrate. At low temperatures or low T emperaturunterschieden can be dispensed with such a step of temperature adjustment. Step 270 may be performed in the medium of air. Alternatively or additionally, instead of air or in addition to the air, an inert gas may be arranged. Step 270 may also be carried out using an IPA dryer (IFA = isopropyl alcohol). Alternatively or additionally, it is also possible to use a hot air which, for example, conducts a stream of nitrogen over the semiconductor substrate.

Step 260 may be after ozone-based treatment and prior to drying in step 270, or before one end of the process. The end of the Method may include depositing the semiconductor substrate, which may also be understood as a drying, for example in ambient air. Step 260 may include wetting the semiconductor substrate with a medium comprising at least one of water, ozone, hydrofluoric acid, and / or hydrogen chloride. A possible ozone concentration is in the range of 1 ppm to 5 ppm or less. The time that the semiconductor substrate contacts ozone in step 260 and / or the concentration thereof is configured to clean off any residue from step 270, while in step 750, the substrate itself may be treated with ozone.

Like the other rinsing steps, rinsing may be performed in step 260 in a temperature range of 5 ° C to 90 ° C.

3 shows a schematic flowchart of a method 300 according to an exemplary embodiment. Method 300 differs from method 200 with respect to step 350. Step 350 is performed in place of step 250 and includes removal of the porous silicon and / or the metal. While this is obtained in the method 200 by the ozone-based treatment, optionally combinatorial, another step of removing the porous silicon and / or the metal may be performed in step 350, for example, by performing an alkaline post-purification and / or by using an acidic After cleaning is carried out. It is understood that in step 350 also several partial steps are executable. According to embodiments, a method may also include steps 250 and 350.

4 shows a schematic flowchart of a method 400 according to one exemplary embodiment. Compared to the methods 200 and 300, the method 400 differs from these embodiments in that the method comprises a step 451 in which an alkaline post-purification is performed. This step may be after the optional step 240. In a step 452, which can be carried out after step 451, the semiconductor substrate is rinsed. The step 452 may be the same or similar to the step 220. After the step 452, an acid post-cleaning may be performed in a step 453, in which, for example, the metal cleaning is performed.

According to an advantageous aspect of the present examples, the ozone-based treatment can be used to remove the porous silicon and / or the Perform metal cleaning, which means removing the metal residues. Although it is known for example from US 6,503,333 B2 to use ozone for rinsing, as shown for example with reference to FIG. 5. Steps 32 and 36 described there relate to the two RCA cleaning baths, with a quick dump rinse purging comprising ozone (O3) after each bath. Also in DE 10 2010 054 370 A1 a use of ozone for cleaning is described. The alkaline etch process is combined with an additional purification step using hydrofluoric acid and ozone to provide a polished and clean surface that is used for Si0 ₂ / SiN _x stack passivation. Here, however, only a removal of detergent residues occurs.

In contrast, the use of the ozone-based treatment in step 250 offers the possibility of reducing the number of chemical process steps, since at the same time the porous silicon materials as well as the metals and optionally also the organic compounds can be cleaned off. Thus, a reduction in the number of rinsing steps can be obtained. This allows the reduction of the process time and thus an increase in throughput based on existing plants and / or processes. Furthermore, a reduction of the chemical consumption is made possible and a smaller dimension of the sequentially operating plants, that is, shorter plants. Further advantages obtained therefrom, in particular if the low consumption of chemicals consists in avoiding hydrogen chloride, potassium hydroxide and / or hydrogen peroxide, lies in the low costs for operating the plant. Also, the smaller number of purification steps makes it possible to obtain lower costs. Indirectly, disposal costs can also be saved since fewer (different) wastewater types are obtained.

In the present case, however, it has been recognized that ozone can be made to remove porous silicon and / or perform metal cleaning and / or cleaning of the organic compounds by treating the surface of the textured silicon substrate with the ozone-based treatment.

6 shows a schematic flow diagram of a prior art method 600 that is used to remove the porous silicon and perform the metal cleaning. For this purpose, the method 600 comprises a step 630 which, for example, can be implemented as step 1030 of the method 1000 and is used to remove the porous silicon. Furthermore, the method 600 includes a step 640 that for metal cleaning, such as performing step 1040 of method 1000.

FIG. 7 shows a schematic flowchart of a method 700 according to an embodiment comprising a step 750 of ozone-based treatment. By means of step 750, not only steps 630 and 640 of method 600 may be performed, but also step 160 of cleaning the surface of the textured silicon substrate from the organic compounds.

The ozone-based treatment may thus include the etching of porous silicon, i. h., the removal thereof, and combine the metal cleaning in one step. Alternatively or additionally, the ozone treatment may also be used to remove organic residues. The ozone treatment 750 can be carried out, for example, in at least one step, which means that it can also be carried out repeatedly or iteratively.

Ozone concentrations of ozone contained, for example, in a liquid, such as aqueous solution in a bath in which the semiconductor substrate is dipped or which is sprayed over the semiconductor substrate may be in a range of at least 1 to at most 150 ppm. Preference is given to concentrations of at least 5 or at least 10 ppm. Such a solution may comprise water, an acid, hydrofluoric acid and / or hydrogen chloride. The solution may preferably have a pH in a range of at least 0 and at most 7 and be used at a process temperature of at least 5 ° C and at most 80 ° C. Preference is given to temperatures of at least 20 ° C and at most 65 ° C or at least 50 ° C and at most 65 ° C. That is, in the ozone-based treatment, the ozone may be dissolved in or part of an aqueous solution, so that wetting the semiconductor substrate with the aqueous solution causes the aqueous solution to react with the semiconductor substrate (s) thereon. The ozone can occur in addition to the form in the dissolved state, even in the form of elementary gas bubbles. This is the combination of dissolved ozone and gaseous ozone. The ozone gas bubbles can in one example positively affect the flow to the wafer and remove residues more effectively from the surface. The wetting can take place by means of a bath, into which the semiconductor substrate is introduced, and / or by means of spraying. The described methods can be carried out in devices designed for this purpose. For this purpose, both applications as a batch method (devices with multiple wells) or in-line methods (devices for spraying the semiconductor substrate) are provided. This means that devices are provided with at least one bath and / or a trough for receiving the wafer and / or at least one transport path is provided, along which the wafer is treated. This can be done for example by spraying or the like. In a batch process, the wafer is immersed in the process solution while being treated during in-line transport.

The ozone-based treatment is particularly advantageous combined with the cleansing of the organic matter. Such a method may thus also be referred to as a method for treating etched surfaces of a semiconductor substrate using ozone-containing medium. Thus, the embodiments described herein and in this context relate to a method and apparatus for treating a textured silicon substrate, and more particularly to a method of cleaning using an ozone-containing medium. It is compared to the prior art, not focused on the rinse, but on a separate step using the ozone-containing medium, in which the corresponding and to be removed substances are removed by the ozone. This means that the ozone interacts with the semiconductor substrate or the residues.

Referring again to FIG. 7, step 210 for etching the semiconductor substrate is also optional. If the method 700 is configured to include step 210, it may be performed prior to ozone-based processing 750 and performed to obtain the textured silicon substrate. As already explained above, the ozone-based treatment with hydrofluoric acid and / or hydrogen chloride can be carried out. Again, etching may include at least one of metal assisted chemical etching, electrochemical etching, acidic isotropic texture etching, and acid isotropic texture etching with organic and / or inorganic additives. The etching may alternatively or additionally comprise chemical edge isolation and / or surface smoothing and / or selective emitter removal and / or saw damage removal, and / or one-sided treatment or two-sided treatment. FIG. 8 schematically illustrates an example of an apparatus 80 for performing a method according to the present disclosure. The device 80 comprises a process media supply device for providing media for cleaning, alkaline post-cleaning and acid surface refinishing. The device 80 further includes a substrate handling device configured to position the substrate 82. For example, the substrate 82 may be a wafer. More specifically, the process media delivery device may be configured to include rollers 86 that permit transport and wetting of the substrate 82 with an acidic or alkaline and / or ozone containing medium. For example. For example, at least one of the rollers 86 may have a cavity for receiving the medium and may be formed so that the medium can reach the substrate through a lateral surface, for example over a porous surface of the roller. Alternatively or additionally, the process media supply device may comprise a media pool in which the acidic or alkaline and / or ozone-containing medium is located. It is understood that the apparatus 80 may include a plurality of rollers and / or media basins for communicating the substrate 82 with different media. Alternatively, the roller and / or the basin between individual steps can be emptied, optionally cleaned and refilled.

The substrate handling device has rollers 86, over which the substrate 82 is transported. The rollers 86 may represent a horizontal transport system, which means that there may be functional integration between the process media supply device and the substrate handling device. The rollers 86 may function to transport the media to the underside of the substrate 82. For example, for this purpose, the rollers 86 may be at least partially arranged in the medium and have a porous or sponge-like surface or provide the medium from an inner hollow body. Thereby, the underside of the substrate 82 can be wetted with the medium and thus treated.

9 shows an alternative example of an apparatus 90 for carrying out a method according to the present disclosure, in which the substrate handling device is in turn implemented as a horizontal transport system with rollers 86 over which the substrate 82 is transported. The device 90 may be similar to the device described in DE 10 2009 060 931 A1 or WO 201 1/076920 A1, so that, for example, the device 90 for treating silicon wafers 82 is shown as silicon substrates, in the direction of passage of these silicon wafers. Wafer 82. They lie along a horizontal Transport path, which is formed by transport rollers 86 on transport shafts 87. Several silicon wafers can be driven side by side through the system 90 and many behind each other at a small distance. Above the transport path along which the substrate 82 is moved, the process media supply device may comprise a still pipe 94 provided as a wetting device, which has a distance of a few centimeters to the top of the substrates 82, such as silicon wafers and extends over the entire width of the transport path , The surge pipe 94 or more still pipes 94 in a row cover the transport path in length. The distance of the surge pipes 94 may be, for example, about 15 cm, but possibly also slightly more or less or even change in the course of the transport path.

Furthermore, a subsequent metering 98 for replenishing additive as a separate connection can be provided on the stilling pipe 94. Here, an additive mentioned above or several of them can be added or added to the etching solution 85. This can be done so shortly before the application of the etching solution 85 from the stilling tube 94, that evaporation of the aforementioned volatile additives is kept very low or can be completely avoided.

The surge pipe 94 has on its underside a plurality of surge nozzles 96, which may be formed as simple holes, openings or slots. Through them, the medium or the etching solution 85 can emerge and come on the top of the silicon wafer 82 and distribute there, as shown. In contrast to the alkaline etching solution described in DE 10 2009 060 931 A1, it is possible to use another, for example, acidic etching solution, as described, for example, in DE 10 2007 063 202 A1, in which case the cleaning is additionally carried out. A method described there can be carried out in two steps. Both steps can use acid etching solutions. In the first step, focusing on the texture of the top, and in the second step on a polish from the bottom. Between the steps a rinsing with water can take place.

According to one embodiment, alternatively or in addition to the surge nozzles 96, the process media delivery device may include lower spray nozzles and upper spray nozzles to provide the media from both sides relative to the substrate 82 to treat both major surfaces of the wafer 82. Alternatively, spray nozzles may be provided only on one side. Although, in FIG. 9, five surge nozzles 96 are shown on FIG. can another number, z. B. only one nozzle or a higher number, such as two, three, four, six, ten or more, may be provided.

10 shows an alternative example of an apparatus 120 for performing a method in accordance with the present disclosure in which the process media provider includes a process media bath 122 in which the media 84, such as an acidic media, is located.

A substrate handling device 124, which is only very schematically shown in FIG. 10, is designed to place the substrate 82 in, for example, a horizontal orientation (left-hand part of FIG. 10) or in a vertical orientation (right-hand part of FIG. 10) Dip medium 84. The substrate handling device 124 may for this purpose include suitable holders or grippers for simultaneously gripping and dipping substrates into the medium 84, one or more substrates at a time.

In examples, the substrate handling device may include transport rollers or transport chains described in more detail, which are configured to float one or more substrates over the surface of the media 84, or formed to one or more substrates Substrate substrates in the medium 84.

The medium 84 may each be at least one medium of the respective process step described in connection with the methods of the disclosure set forth herein.

Although some aspects of the present disclosure have been described as features associated with a device, it will be understood that such description may also be considered as a description of corresponding method features. Although some aspects of the present disclosure have been described as features associated with a method, it will be understood that such description may be considered as a description of corresponding features of a device and the functionality of the device, respectively.

The examples described above are only illustrative of the principles of the present disclosure. It should be understood that modifications and variations of the arrangements and details described are obvious to those skilled in the art. It is therefore It is intended that the disclosure be limited only by the appended claims and not by the specific details set forth for the purpose of describing and explaining the examples.

Claims

claims

A method of treating a surface of a textured silicon substrate comprising

Cleaning (1 10; 160; 230; 750) the surface of the textured silicon substrate to effect removal of organic compounds present on the surface of the textured silicon substrate;

Removing (110; 170; 250; 350; 451; 630; 750) porous silicon at the surface of the textured silicon substrate, and

Performing a metal cleaning (1 10; 180; 250; 350; 453; 640; 750) of the surface of the textured silicon substrate.

2. The method of claim 1, wherein the cleaning (110; 160; 230; 750), the removal (110; 170; 250; 350; 451; 630; 750) and the export of metal cleaning

(110; 180; 250; 350; 453; 640; 750) is performed in a common step (110).

3. The method of claim 2, wherein the common step is carried out using a medium comprising ozone, HF and HCl.

4. The method of claim 3, wherein the HF has a concentration of at most 1, 5% and HCl has a concentration of at most 1, 5%.

5. The method according to any one of the preceding claims, wherein the cleaning (110;

160; 230; 750) of the surface is carried out with an oxidative and / or an alkaline component.

6. The method of claim 5, wherein the oxidative component comprises at least one of hydrogen peroxide and ozone and / or the alkaline component comprises potassium hydroxide.

The method of any one of claims 1 to 4, wherein the cleaning (110; 160; 230; 750) of the surface comprises RCA cleaning, wherein the RCA cleaning comprises two-bath cleaning, wherein a first bath is an aqueous solution with ammonium hydroxide and hydrogen peroxide, and wherein a second bath includes an aqueous solution of hydrochloric acid and hydrogen peroxide.

8. The method according to any one of the preceding claims, wherein the cleaning (110;

160; 230; 750) of the surface causes removal of porous silicon, organic compounds and / or texture additives.

9. The method according to any one of the preceding claims, wherein the cleaning (110;

160; 230; 750) of the surface at a temperature ranging from 40 ° C to 70 ° C.

The method of any one of the preceding claims, further comprising etching (210) performed prior to cleaning (110; 160; 230; 750) the surface.

The method of claim 10, wherein the etching (210) comprises at least one of metal assisted chemical etching, electrochemical etching, acid isotropic texture etching, or acid isotropic texture etching with organic or inorganic additives.

The method of claim 10, wherein the etching (210) comprises an acidic isotropic texture etching with organic or inorganic additives, and the texture comprises HF, HNOa, and an additive or HF, HNO 3, H ₂ O, and an additive.

13. The method according to any one of claims 10 to 12, wherein the etching (210) takes place at a temperature which is in the range of 10 ° C to 30 ° C.

14. The method of claim 12, wherein a duration of the etching (210) is in the range of 0.5-10 minutes.

The method of any one of claims 10 to 14, wherein the etching (210) comprises chemical edge isolation, surface smoothening, selective emitter removal, saw damage removal, unilateral treatment or bilateral treatment.

The method of any one of the preceding claims, further comprising: drying (270) performed after cleaning (160; 230).

17. The method of claim 16, wherein said drying (270) is carried out at a temperature which is in a temperature range of 25 ° C to 100 ° C.

18. The method according to any one of claims 16 or 17, wherein the drying (270) is carried out at a constant temperature or a variable temperature profile.

The method of any of claims 16 to 18, wherein said drying (270) is performed on a medium, said medium comprising at least one of air and inert gas.

20. A method according to any one of the preceding claims, further comprising at least one:

Rinsing (220, 240, 260, 452), which is between etching and surface cleaning and / or surface cleaning and alkaline post-cleaning, and / or alkaline post-cleaning and acid rinsing, and / or between acid rinsing and drying.

21. The method of claim 20, wherein the purging (220, 240, 260, 452) is by means of a medium, wherein the medium comprises at least one of water, ozone, HF or HCl.

22. The method according to any one of claims 20 or 21, wherein the purging (220, 240, 260, 452) is carried out in a temperature range of 5 ° C to 90 ° C.

A method according to any one of the preceding claims, wherein the removal (110; 170; 250; 350; 451; 630; 750) of porous silicon is accomplished by alkaline post-cleaning (451) of the surface of the textured silicon substrate, and / or wherein the metal cleaning (110; 180; 250; 350; 453; 640; 750) is performed by an acid post-cleaning (453) of the surface of the textured silicon substrate.

24. The method according to any one of claims 1 to 22, wherein the removal (110; 170;

250; 350; 451; 630; 750) of porous silicon and / or performing the metal cleaning (110; 180; 250; 350; 453; 640; 750) by an ozone-based treatment (110; 750) of the surface of the textured silicon substrate.

The method of claim 24, wherein the ozone-based treatment (110; 750) is performed at an ozone concentration of 1 to 150 ppm in an ozone-containing acidic medium.

26. The method of claim 24 or 25, wherein the ozone-based treatment (110; 750) with HF and / or HC! is carried out.

27. A method according to any one of claims 24 to 26, wherein the ozone-based treatment (110; 750) is performed in a pH range of 0 to 7.

28. The method according to any one of claims 26 to 27, wherein the ozone-based treatment (1 10, 750) is carried out in a temperature range of 5 ° C to 80 ° C.

29. The method of any of claims 24 to 28, further comprising:

Etching (210) performed prior to the ozone-based treatment (110; 750) to obtain the textured silicon substrate.

30. The method of claim 29, wherein the etching (210) comprises at least one of metal-assisted chemical etching, electrochemical etching, acid isotropic texture etching, or acid isotropic texture etching with organic or inorganic additives.

31. The method of claim 29, wherein the etching comprises a chemical edge isolation, surface smoothing, selective emitter removal, saw damage removal, one-sided treatment, or two-sided treatment.

32. The method of claim 24, further comprising:

Drying (270), which is carried out after ozone-based treatment (110; 750).

33. The method of claim 32, wherein said drying (270) is carried out at a temperature ranging from 25 ° C to 100 ° C.

34. The method according to any one of claims 32 or 33, wherein the drying (270) takes place at a constant temperature or has a variable temperature profile.

The method of any one of claims 32 to 34, wherein said drying (270) is performed on a medium, said medium comprising at least one of air and inert gas.

36. The method according to any one of claims 24 to 35, further comprising at least one:

Rinsing (220, 240, 260, 452) comprising between etching (21) and ozone-based treatment (25) and / or between ozone-based treatment (25) and drying (29).

37. The method of claim 36, wherein the purging (220, 240, 260, 452) is by means of a medium, wherein the medium comprises at least one of water, ozone or HF.

38. The method of claim 37, wherein when the rinsing medium (220, 240, 260,

452) ozone is purged at an ozone concentration of 1 to 3 ppm.

39. The method according to any one of claims 36 to 38, wherein the purging (220, 240, 260, 452) in a temperature range of 5 ° C to 90 ° C is performed.

40. Apparatus (80; 90; 120) for performing a method according to any one of claims 1 to 39, comprising process media supply means for providing media for cleaning, alkaline post-cleaning and acidic post-cleaning of the surface, and substrate handling means (124) position the silicon substrate (82) to treat the surface.

41. The apparatus (80; 90; 120) according to claim 40, wherein the process media supply device has at least one porous roller for transporting and wetting the substrate and / or a process media basin.