DE10212657A1 - Wet chemical cleaning of a silicon wafer comprises initially contacting a hydrophobic surface partially covered with polishing agent, and contacting with an aqueous solution containing an oxidant - Google Patents

Abstract

Process for the wet chemical cleaning of a silicon wafer comprises initially contacting a hydrophobic surface partially covered with polishing agent; and contacting with an aqueous solution containing an oxidant. Preferred Features: The polishing agent has a pH value of 8-12.5 and contains 0.1-10 wt.% SiO2 as abrasive agent or colloid.

Description

The invention relates to a method for cleaning a half silicon conductor disc after polishing. Such Silici discs with polished, cleaned surfaces are suitable for use in the manufacture of integrated electronics components.

A silicon wafer for the production of inte Large electronic components must be a variety have properties. These properties must be the intended use, in particular the line density of the Component, meet: The higher the planned integrati density, the stricter the requirements are, for example local flatness and number of surface defects.

The final surface of such a silicon wafer will be generated by one or more polishing processes. So you can Polish the rounded edge of a silicon wafer to make one Counteract adherence of particles, which the components Could interfere with the manufacturing process. The flatness of the silicon disk is removed by disturbed crystal layers by egg attacking on one side on the front or on both sides Removal polishing step generated. A mostly subsequent one Surface polish - also called veil free polish - provides a low roughness and low defect level for the Manufacture of semiconductor components provided fore te of the silicon wafer safely. Examples of polishing processes Silicon wafers are from DE 199 05 737 C2, DE 100 04 578 C1 and DE 100 12 840 C2 known.

In these processes, the polishing is carried out by moving the disk surface over a polishing cloth in the presence of a polishing agent containing abrasives or colloids. In the case of silicon wafers, an alkaline polishing agent with suspended or colloidally dissolved SiO ₂ is suitable, for example according to DE 198 36 831 A1. Immediately after polishing, the freshly polished silicon surface is hydrophobic, i.e. water-repellent. In order to protect the very reactive silicon surface terminated with Si-H end groups and therefore sensitive to etching and uncontrolled oxidative attack by atmospheric oxygen, the prior art sees for example in the form of DE 35 17 665 A1, EP 863 540 A1, DE 101 08 542 A1 and US Pat. No. 6,230,720 B1, immediately after the polishing, first of all before an oxidative treatment which produces an SiO ₂ layer of at least 10 to 15 Å in thickness and thus prevents further attack on the silicon surface. According to EP 1 065 708 A2, US Pat. No. 5,954,888, US Pat. No. 5,996,594 and US Pat. No. 6,099,662, treatment with brushes or roller sticks and megasound to remove particles and / or cleaning solutions with the one, in some cases in combination with such an oxidation Polishing agents with a comparable pH value, for example based on ammonia and quaternary ammonium compounds, are an advantage.

The disadvantage of these prior art methods is that their cleaning effect on freshly polished, with polishing agents not contaminated and chemically very reactive silicon wafers sufficient to manufacture modern microelectronic construction allow elements in sufficient yields.

The suitability of aqueous hydrofluoric acid as the first treatment medium at the beginning of a cleaning sequence is known for semiconductor wafers with a coating. Semiconductor wafers coated with electronic structures, which have no exposed silicon surface, are treated with solutions which may contain aqueous hydrofluoric acid (HF) after chemical-mechanical planarization, for example of layers according to US Pat. No. 5,389,194 and JP 2000 235 965 A. The cleaning and drying of polished hydrophilic silicon wafers, that is to say with a native SiO ₂ layer of about 1-1.5 nm, in hydrofluoric acid / ozone combination processes is described, for example, in DE 195 31 031 C2, US Pat. No. 5,665,168 and EP 708480 A1 be claimed. For the cleaning of a chemically very sensitive hydrophobic silicon wafer contaminated with polishing agent, the use of such methods has not previously been considered.

It was therefore the task of a process for wet chemistry cleaning of silicon wafers immediately after the poli To provide which leads to a lower particle and Defect density on the surface of the silicon wafer in the ver leads directly to the results according to the prior art. because In addition, this process should relate to the manufacturing costs ten and other properties of the silicon wafers at least be comparable to methods according to the prior art.

The invention relates to a method for wet chemical Cleaning a silicon wafer after performing a chemical-mechanical polishing in the presence of an abrasive or colloid-containing aqueous polishing agent which thereby is characterized that at least one with the polishing agent partially covered, hydrophobic surface of the silicon wafer first with an aqueous hydrofluoric acid solution and then with at least one oxidizing agent aqueous solution is brought into contact.

Essential feature of the cleaning method according to the invention It is that the freshly polished, covered with polish and chemically very sensitive hydrophobic silicon wafer initially by treatment with aqueous hydrofluoric acid solution hydrophobic hold and freed of adhering impurities and only then a homogeneous, not by oxidation in aqueous solution quality of embedded dirt particles pregnant protective oxide film is generated. This means an ab return from the strategy documented in the prior art, the first an oxidative protection of the silicon surface and only then provides for cleaning.

The starting product of the process is a semiconductor wafer Silicon, the process steps sawing, rounding edges, Subsequent surface grinding, lapping, etching and / or polishing and had been freshly polished with a polishing agent  has an unclean surface. The end product of the process can be a silicon wafer with a polished edge that is white terverarbeitung supplied for example by abrasive polish can be. The end product of the process can also be a silicon disc with polished front and if necessary also be polished back, that of further processing tion, for example, be supplied by surface polishing can. The end product of the process can also be a silicon pane with a polished front, which is one Further processing, for example by depositing an epi tactical coating and / or by applying electroni shear components can be supplied.

In principle, the method according to the invention can be used for cleaning various disc-shaped bodies after polishing be used. Its full advantages can be seen at Manufacture of silicon wafers that are used for Smoothing, leveling and / or eliminating surface defects be subjected to a chemical-mechanical polish. For it is self-evident to the person skilled in the art that a silicon disk up to 1 atomic% foreign material, for example boron, Carbon, nitrogen, phosphorus, arsenic or oxygen ent can hold what the properties of the crystal lattice about targeted with regard to electrical or defect properties influence. The invention can also be used without problems run such dopants. Silicon in single crystal Talliner form with a crystal orientation (100) for further use in the manufacture of electronic components, for example processors and memory elements, is in the frame the invention particularly preferred. Silicon wafers with a Diameter between 100 mm and 450 mm and a thickness between 300 µm and 1200 µm are also particularly preferred.

To carry out an edge polish, which the fiction commercial cleaning procedures are to follow Edge polishing machines are available, the construction of which Oriented diameter of the discs to be polished. It can be carried out in such a way that rotation of the  Silicon wafer with a slanted, with polishing cloth pasted the polishing plates first, for example the one lower one, and then the other one, for example the upper one Flank of the pane edge is polished. However, it is also possible to polish the entire rounded edge in one step Ren. After creating an all around defect-free polished edge, which according to preferably 0.5 to 15 μm and particularly preferably 2 to 10 µm silicon ablation occurs, based on the surface of a Edge, becomes the silicon wafer of cleaning according to the invention fed. The silicon wafer has an outer circumference breakthrough orientation feature, for example an off saving like a notch, this area can also edge to be polished; Standard machines have separa for this facilities with appropriately dimensioned polishing cloth units.

As part of the execution of an abrasive polishing step be the possibilities are only one side or the front on both sides sequentially the back and the front or polish both sides simultaneously on both sides. With the one side polishing, it is possible to pass through the silicon wafer Wax, adhesion and / or vacuum on a carrier device hold. When performing both at the same time polish, for which, as for the one-sided polish, commercially available lishing polishing systems are available, a single runners covered with one or more silicon wafers disc are located in the center of the system and next to rotation also perform lateral movements. But there is also the possibility , usually several rotor disks on a planetary orbit rotating to move the plant center. Both types of Plants essentially consist of a freely horizontal rotating lower polishing plate and a freely rotating horizontally removable upper polishing plate, both covered with a polishing cloth and allow with continuous supply of polishing by means of polishing silicon wafers on both sides ben. The rotor disks can, for example, be made of metal, Plastic or metal coated with plastic. After creating, for example, a polished front and  a polished back of the silicon wafer at the same time two-sided polishing with removal of preferably 2 to 30 µm and particularly preferably 5 to 20 µm silicon removal per screen te is the silicon wafer for cleaning according to the invention guided.

The surface polish to provide a haze-free polished front with low defect density, which as Spe case of one-sided polishing can be understood also within the scope of the invention on a Handelsblübli use systems with one or more polishing plates, being either a single silicon in a polishing process wafer or several silicon wafers polished at the same time be, each attached to its own carrier device and are thus rotating over a polishing cloth the. Systems with two polishing plates are part of the Erfin Particularly preferred because of a graded surface treatment with different hard polishing cloths and ver various polishing agents the desired very smooth, low-defect Surface can be created. The removal is preferred from 0.1 to 2 µm silicon from the front. An execution the surface polish also on the back of the Silici slicing is possible, but does not make any significant difference parts.

The market sets standards for these different types of polishing tailor-made polishing cloths, preferably on polyure than basis, if necessary reinforcing polyester fibers, exist. Cloths for edge polishing have one particularly preferred hardness from 30 to 70 (Shore A) and wipes for polishing from 60 to 90 (Shore A); for the waiters surface polishing is particularly preferred for soft cloths Commitment.

A large number of aqueous suspensions of abrasive substances or aqueous brine or gels with finely divided colloids can be used as the polishing agent, which is preferably fed continuously. Suitable solids are, for example, SiO ₂ , TiO ₂ , ZrO ₂ , CeO ₂ , SnO ₂ , Al ₂ O ₃ , Si ₃ N ₄ and / or SiC. The polishing agent can also contain various additives, such as inorganic acids and bases, for example HCl, H ₃ PO ₄ , NH ₄ OH, NaOH and KOH, inorganic salts such as NaH ₂ PO ₄ , CaCl ₂ , Na ₂ CO ₃ and K ₂ CO ₃ , organic acids and bases, such as acetic acid, citric acid and TMAH (tetramethylammonium hydroxide), organic salts, such as sodium citrate and quaternary ammonium salts, complexing agents and their salts, such as EDTA (ethylenediaminetetraacetate), and surface-active substances and de other salts, such as surfactants. Depending on the composition, the pH and particle size of the solid can vary within relatively wide limits. Within the scope of the invention, preference is given to using an alkaline polishing agent based on silicon dioxide (SiO ₂ ) with a pH which is particularly preferably adjusted to from 8 to 12.5 and an SiO ₂ content of 0 by adding inorganic salts and / or bases , 1 to 10 wt .-% with an average particle diameter of 1 to 100 nm.

After executing such a polishing step, a silicon wafer is present which has a very chemically reactive surface with Si-H end groups in the area of the polishing, for example on the edge in the case of edge polishing or on the front in the case of surface polishing is contaminated with abrasive or colloid-containing polishing agent, for example an alkaline polishing agent containing SiO ₂ particles. Exposure of the wafer surface over a period of time that would go beyond about 20 to 120 seconds would inevitably result in an etching of the surface by adhering polishing agent in connection with a later no longer cleanable adherence of the solids and by roughness differences in the silicon surface Lead to attack by atmospheric oxygen.

The invention therefore provides for the surface of the silicon wafer to be brought into contact with aqueous hydrofluoric acid solution immediately after polishing, that is to say within about 20 to 120 seconds. For example, by spraying or rinsing the freshly polished disc with ultrapure water or by temporarily storing it in a water bath, this period of time can be slightly extended in order to do justice to real times in operational practice and to counteract a potential material jam, for example to 2 to 15 minutes. The aqueous hydrofluoric acid solution preferably has an HF content of 0.1 to 10% by weight and particularly preferably 0.2 to 3% by weight. The treatment with the hydrofluoric acid solution can be carried out by spraying, rinsing or immersion; it is also possible to feed them in a roller stock from rotating pairs of rollers, for example made of PVA (polyvinyl alcohol). All of the above-mentioned variants are preferred when rapid, full contact with the surface and an intensive mass transfer are ensured. This treatment prevents the formation of surface Si (OH) ₂ , -SiO (OH) and / or -SiO ₂ , which would occur in air or in particular in oxidizing media, and the Si-H end groups are retained , At the same time, polishing agent solution, for example caustic alkaline solution, is replaced by a non-caustic silicon, residue-free from running surface film of pure hydrofluoric acid solution, and solid parts such as abrasive particles or colloid are effectively washed away, leaving behind a clean, hydrophobic surface without particulate and metal contamination. In particular, the particle removal can be improved under certain circumstances if the hydrofluoric acid solution is preferably 0.001 to 1% by weight and particularly preferably 0.01 to 0.1% by weight of a surface-active substance which is stable under these conditions, for example a surfactant such as ammonium lauryl sulfate, perfluoroalkyl sulfonates or alkylbenzenesulfonic acid / amine ethoxylate preparations is added.

After hydrofluoric acid treatment for a period of preferably 0.1 to 10 min and particularly preferably 1 to 6 min is carried out, the silicon wafer can first with Ultrapure water can be contacted to hydrofluoric acid solution rinse; this water treatment can, for example, by Rinsing or immersing yourself in a bath or something like that called quickdump sink that in one or more cycles emptied and quickly refilled. The in the frame  of the invention performed contacting with the at least however, an oxidizing agent-containing aqueous solution without problems even immediately after the hydrofluoric acid treatment take place, for example, with the oxidizing solution sprayed or rinsed or a used for this purpose Bath is operated with a sufficiently high mass transfer. At this point, too, is the use of a roller mill conceivable and can bring advantages under certain circumstances.

In the simplest case, this second solution contains only one oxidizing agent, for example hydrogen peroxide (H ₂ O ₂ ) or ozone (O ₃ ) or other chemical oxidizing agents. In individual cases there is the possibility of generating the oxidizing agent only in solution, for example by using electrical current or chemical conversion. It is also conceivable to combine several oxidizing agents, although this usually does not bring any advantages. Oxidizing agents are preferred which do not leave any difficult-to-clean residues on the surface of the silicon wafer; the use of H ₂ O ₂ in a proportion of 0.1 to 10% by weight is particularly preferred.

The oxidizing agent leads to the formation of a uniform, non-contaminated SiO ₂ layer in a thickness of 10 to 15 Å on the surface previously cleaned with aqueous hydrofluoric acid solution, which corresponds to the thickness of the natural oxide. With a view to maintaining the absence of particles, it is particularly preferred to add alkaline substances to the oxidizing solution in a proportion of 0.1 to 10% by weight. Examples of suitable bases and basic salts are NH ₄ OH, TMAH, NaOH, KOH, Na ₂ CO ₃ and / or K ₂ CO ₃ . The addition of small amounts of surface-active substances can be advantageous in certain circumstances.

Treatment with this hydrophilizing solution can also principally by spraying, rinsing or immersing as well as in a roll of rotating pairs of rolls for example made of PVA. If this is constructively possible, under the use of megasound supports the cleaning effect and  is also particularly preferred. After the oxidative treatment lung, which for a period of preferably 0.1 to 10 min and from 0.5 to 5 minutes is particularly preferred the surface of the silicon wafer again with ultrapure water act to remove residual solution.

After carrying out the invention in this way, there is a low-metal and low-particle, hydrophilic silicon surface protected with an SiO ₂ layer. The silicon wafers can now be dried according to the prior art, for example with an HF / ozone, marangoni, hot water or spin dryer and fed to their further determination. However, there is also the possibility of further processing the panes in wet form, for example by simultaneously polishing both sides after edge polishing or by additional surface cleaning before carrying out hot processes such as the application of an epitaxial coating, for example after surface polishing.

A particularly preferred implementation of the invention relates to the wet chemical cleaning of a silicon wafer after edge polishing with an alkaline SiO ₂ -containing polishing agent as a single wafer process in a cleaning module integrated directly in the edge polishing machine, which comprises the step sequence cleaning with HF solution - cleaning with H ₂ O ₂ / TMAH solution - Rinse with ultrapure water - Run dry spin.

Another particularly preferred implementation of the invention relates to the wet chemical cleaning of a silicon wafer after edge polishing or after an abrasive polish attacking on one or both sides with an alkaline polishing agent containing SiO ₂ as a batch process in a bath installation, which comprises the step sequence HF / surfactant bath - ultrapure water - Abundance bath - H ₂ O ₂ / TMAH bath with megasound exposure - Ultrapure water abundance bath - Hot water dryer is running.

Another particularly preferred implementation of the inven tion relates to the wet chemical cleaning of a silicon wafer after surface polishing of the front with an alkali-containing SiO _2- containing polishing agent as a single wafer process in a cleaning module integrated directly into the polishing system, which comprises the sequence of spraying with ultrapure water - rinsing with HF / Surfactant solution - rinsing with ultrapure water - rinsing with H ₂ O ₂ / TMAH solution - rinsing with ultrapure water - spin drying or transfer to another cleaning system. This further cleaning system can, for example, use the alkaline bath for particle removal, which is common in the prior art, for example H ₂ O ₂ / TMAH solution with megasound exposure, ultrapure water rinsing, acid bath for metal removal, for example aqueous HCl solution, and / or Use of a roller mill using an aqueous solution containing surface-active substances, each followed by drying.

Such surface-polished silicon wafers can in the form directly for the production of integrated semi-lead ter components are used. If this is for further waiters area improvement required and in the construction of the Components is provided, but can also be standard process an epitaxial coating on the front For example, can be generated from silicon, which is in their electrical properties usually those of silicon disc differs. The application of an epitaxial Silicon layer is preferably done by the CVD process (chemical vapor deposition) by adding silanes to the pane surface che be carried out there at temperatures of 900 ° C to 1250 ° C to elemental silicon and volatile by-products decompose and an epitaxial, i.e. single crystal, Woke up crystallographically based on the silicon wafer form its silicon layer. Silicon layers are preferred epitaxially grown with a thickness of 0.1 to 10 µm.

Silicon wafers produced according to the invention can also be one targeted superficial dopant depletion the, for example, by heat treatment under hydrogen and / or argon is executed and also to an upper  changes in the electrical properties. In addition, the production of layer structures is possible Lich, that of the silicon wafer, a non-conductive layer for example from silicon dioxide or from strontium titanate and a high quality single crystal surface layer of silicon or gallium arsenide for example can hen. All layers of these different products can also be specifically doped with foreign substances.

If necessary, the process can be performed at any point chain insert a heat treatment of the silicon wafer the, for example, a disturbance of near-surface crises Heal layers. In addition, a Laserbe writing for identification of the pane at a suitable place be carried out. A number of other, for certain products required process steps such as the application of back egg polysilicon, silicon dioxide or silicon coatings Umnitrid can also be made according to the Ver realize driving.

Silicon wafers after a chemical mechanical polish cleaned with the inventive method show a significantly higher surface quality, e.g. de Finished by the absence of stains, particles or white light scattering centers than in the state of the art inclined silicon wafers. This finding that a polishing line treatment sequence with aqueous hydrofluoric acid under agitation maintenance of hydrophobicity followed by hydrophilicity tion with at least one oxidizing agent aqueous solution for better results and therefore higher output loot and lower manufacturing costs than polishing lines supply sequences according to the prior art, in which the sili cium disc in the first step was hydrophilized detrimental and unpredictable.

Examples and comparative examples

Examples and comparative examples relate to the production of Silicon wafers with a diameter of 300 mm. The be necessary crystals were pulled according to the state of the art, cut to length, cylindrical ground, portioned, on a han saws the usual wire saw into slices with a thickness of 935 µm and Edge-rounded. A grinding step with a pot followed 600 mesh grit (grit size class 20-30 µm), being sequential from the front and the back each 50 microns of silicon were removed, and one etching step in one Mixture of concentrated nitric acid and concentrated Hydrofluoric acid, with rotation on each side of the disc 10 µm silicon were removed at the same time. The etch process and the process steps described in the following Kan tenpolishing and surface polishing as well as all polishing lines Cleaning was carried out at 20 ° C.

example 1

This example explains how the cleaning according to the invention is carried out after edge polishing. The edges of the silicon wafers were polished on a commercially available 300 mm edge polishing system with an integrated cleaning module using an aqueous polishing agent with an SiO ₂ solids content of 3% by weight and a pH value adjusted to 10.5 by adding potassium carbonate , where a polyurethane polishing cloth with a hardness of 50 (Shore A) reinforced with polyethylene fibers was used. In this case, the silicon wafer was polished successively by rotating the silicon wafer with a slanted polishing plate glued with a polishing cloth, first the lower and then the upper flank of the edge of the wafer.

The cleaning was carried out as a single-pane process in the integrated cleaning module immediately after polishing, in the following sequence: spraying with aqueous HF solution (0.25% by weight) - spraying with H ₂ O ₂ / TMAH solution (H ₂ O ₂ 1% by weight; TMAH 0.25% by weight) - rinsing with ultrapure water - dry spin. After a visual inspection under highly concentrated light, the silicon discs processed in this way had a completely polished edge with no visible defects or dirt.

Example 2

This example explains how the cleaning according to the invention is carried out after simultaneous polishing on both sides; For this purpose, the edge-polished silicon wafers produced according to Example 1 were used. A commercially available system for double-sided polishing was available, which was covered with five rotor disks made of stainless steel, each with three circular, equally spaced, circular recesses lined with PVDF (polyvinylidene difluoride) with an inner diameter of 301 mm and the simultaneous polishing of 15 300 mm silicon wafers made possible. A polyurethane polishing cloth with hardness 74 (Shore A) reinforced with polyethylene fibers and an aqueous polishing agent with an SiO ₂ solids content of 3% by weight and a pH adjusted to 11.5 by adding potassium carbonate were used , At a temperature of the upper and the lower polishing plate of 40 ° C each 15 µm silicon was removed per side of the disk, so that the thickness of the silicon wafers was 775 µm.

After the desired silicon removal had been achieved, the polishing agent was introduced for a short period of 1 min by adding ultrapure water with a small proportion of 0.05% by weight of alkylbenzenesulfonic acid / amine ethoxylate surfactant. The silicon wafers were removed from the polishing system, placed in a transport trolley filled with ultrapure water with a holding device, and fed to a bath cleaning system in which the 15 simultaneously polished wafers were cleaned at the same time (batch cleaning). The first bath contained a mixture of aqueous HF solution (0.5% by weight) with 0.05% by weight alkylbenzenesulfonic acid / amine ethoxylate surfactant. After an ultrapure water bath followed by a megasonic bath with an aqueous H ₂ O ₂ / TMAH solution (H ₂ O ₂ 1 wt .-%; TMAH 0.25 wt .-%), another ultrapure water bath and a hot water dryer for simultaneous drying of the 15 silicon wafers. All baths were made from abundance baths; the dwell time was 3 minutes in each bath. After cleaning and drying, the silicon wafers were again subjected to a visual inspection under highly concentrated light. On average, 20 stray light defects were found on the polished front and the polished back.

Comparative Example 1

The procedure was as described in Example 2 with the only difference that the bath sequence in the polishing cleaning was changed in such a way that the silicon wafers were first placed in the H ₂ O ₂ / TMAH solution and then in the HF / surfactant solution, each followed by ultrapure water treatment. This time, the visual inspection under highly concentrated light after drying showed an average of 55 stray light defects per side of the pane.

Example 3

This example explains how the cleaning according to the invention is carried out after a surface polishing; the edge-polished silicon wafers produced according to Example 2 and polished on both sides were used for this purpose. A commercially available system with two polishing plates for surface polishing was available, on which the silicon wafers held by a carrier device by means of adhesion could be individually polished. Plate 1 was polished with a soft polishing cloth with the addition of a polishing agent with 3% by weight SiO ₂ in ultrapure water and a pH value adjusted to 10.5 by adding K ₂ CO ₃ while removing 0.45 μm silicon. Plate 2 was covered with a very soft polishing cloth; with a polishing agent, which contained 1 wt .-% SiO ₂ in ultrapure water and had a pH of 9.8, a further 0.05 μm silicon was removed. At the end of the polishing process, ultrapure water was supplied for a period of 20 seconds.

Immediately after polishing, the freshly polished silicon wafers were individually transferred to a cleaning module integrated in the polishing system, in which they were successively sprayed with the following aqueous solutions:

• 1. 0.25% by weight HF plus 0.025% by weight alkylbenzenesulfone acid / amine ethoxylate surfactant
• 2. ultrapure water
• 3. H ₂ O ₂ 1% by weight plus TMAH 0.25% by weight
• 4. ultrapure water

Subsequently, the silicon wafers were passed through a roller block with four counter-rotating upper and lower PVA rollers, each with an aqueous solution of 0.05% by weight sulfosuccinic acid and 0.025% by weight alkylbenzene sulfonic acid / aminethoxylate surfactant was supplied. The discs were spun dry after a brief rinse with ultrapure water to remove the surfactant. A characterization of the surface quality with a laser-based particle counter resulted in an average of 10 defects with dimensions equal or greater than 0.12 µm for the surface-polished and cleaned front. After the deposition of an epitaxial coating of 3 µm silicon in a commercially available 300 mm epitaxial reactor at a reactor chamber temperature of 1090 ° C on the front side, with SiHCl ₃ being used as the silicon component, an average structural defect was found using the same measurement method per slice with a size of 0.3 µm or greater.

Comparative Example 2

The procedure was as described in Example 3 with the one only difference that the spraying (1) with hydrofluoric acid / Ten Sid solution not followed by spraying (2) with water was carried out. Characterization on laser particle tough This time there were an average of 24 defects on the front Dimensions equal to or greater than 0.12 µm, and according to the epitakti coating, an average of four structural defects per Disc found.

Claims (14)

1. A method for wet-chemical cleaning of a silicon wafer after carrying out a chemical-mechanical polishing in the presence of an aqueous polishing agent containing abrasive or colloid, characterized in that a hydrophobic surface of the silicon wafer which is at least partially covered with the polishing agent is initially treated with an aqueous hydrofluoric acid solution and then is brought into contact with an aqueous solution containing at least one oxidizing agent. 2. The method according to claim 1, characterized in that the polishing agent had a pH of 8 to 12.5 and contained 0.1 to 10 wt .-% SiO ₂ as an abrasive or colloid. 3. The method according to claim 1 or claim 2, characterized records that the chemical-mechanical polish as a polish ner edge of the silicon wafer with removal of 0.5 to 15 microns Silicon, based on the surface of an edge, executed has been. 4. The method according to claim 1 or claim 2, characterized shows that the chemical-mechanical polish at the same time Two-sided polishing of a front and a back the silicon wafer with removal of 2 to 30 µm silicon per Page was executed. 5. The method according to claim 1 or claim 2, characterized shows that the chemical-mechanical polish as a removal lit the front of the silicon wafer while removing 2 up to 30 µm silicon was executed. 6. The method according to claim 1 or claim 2, characterized records that the chemical-mechanical polish as a surface Chenpolitur a front of the silicon wafer under removal from 0.1 to 2 µm silicon was carried out.   7. The method according to claim 6, characterized in that min treatment of the silicon wafer with an aqueous solution Hydrofluoric acid solution as a single pane treatment in one component the polishing system is executed. 8. The method according to any one of claims 1 to 7, characterized indicates that the contact of the silicon wafer with an aq hydrofluoric acid solution and with at least one oxidation medium-containing aqueous solution by immersion, rinsing, Spraying and / or treatment takes place in a roller mill. 9. The method according to any one of claims 1 to 8, characterized records that the aqueous hydrofluoric acid solution from 0.1 to 10 Wt .-% HF contains. 10. The method according to any one of claims 1 to 9, characterized records that the aqueous hydrofluoric acid solution from 0.001 to 1 Contains% by weight of a surface-active substance. 11. The method according to any one of claims 1 to 10, characterized ge indicates that the at least one oxidizing agent aqueous solution of hydrogen peroxide and an alkaline Component contains from 0.1 to 10 wt .-% each. 12. The method according to any one of claims 1 to 11, characterized ge indicates that the silicon wafer before and / or after the Contact with aqueous hydrofluoric acid solution and with at least one an oxidizing agent-containing aqueous solution with water is brought into contact without any further additives worth mentioning. 13. The method according to any one of claims 1 to 12, characterized ge indicates that one or more further Reini steps and / or drying the silicon wafer to be led.   14. The method according to any one of claims 4 to 13, characterized ge indicates that after cleaning and drying the silicon slice a silicon layer of thickness on the front is grown epitaxially from 0.1 to 10 µm.