CN115588607A - Silicon wafer pretreatment method - Google Patents

Abstract

The invention provides a silicon chip pretreatment method, comprising: providing a silicon chip, performing nitriding treatment on the silicon chip, forming a modified layer doped with nitrogen on the surface of the silicon chip; performing annealing treatment on the silicon chip after the nitriding treatment . The silicon wafer pretreatment method provided by the present invention can form a nitrogen-doped modified layer on the silicon wafer surface through nitriding treatment, which can reduce the oxygen impurity content on the silicon wafer surface and can suppress oxygen precipitation lattice defects in the modified layer Formation; through annealing treatment, the oxygen impurities on the surface of the silicon wafer are further removed, and the lattice defects on the surface are repaired, and finally a silicon wafer with the content of oxygen impurities on the surface and the content of oxygen precipitated lattice defects in line with expectations is obtained. Therefore, the silicon wafer pretreatment method provided by the present invention can effectively reduce the content of oxygen impurities and oxygen-precipitated lattice defects on the silicon wafer surface, thereby improving the yield rate of subsequent manufacturing processes.

Description

A kind of silicon wafer pretreatment method

technical field

The invention relates to the field of semiconductor manufacturing, in particular to a silicon wafer pretreatment method.

Background technique

During the growth of single crystal silicon, the single crystal silicon will be mixed with some oxygen impurities. When these oxygen impurities exceed a certain concentration in the silicon lattice gap, oxygen precipitation will occur. In single crystal silicon with high oxygen impurity content, oxygen precipitation is the crystal lattice. Important types of defects. When oxygen precipitation exists near the surface of the silicon wafer, it will affect the quality and performance of the silicon wafer, and the oxygen precipitation must be controlled. When the oxygen impurity content in the silicon wafer is higher, the oxygen precipitation lattice defects are easier to form, so the oxygen precipitation can be controlled by controlling the oxygen impurity content. During the growth process of monocrystalline silicon, a certain process is used to make a certain depth on the surface of the silicon wafer a clean area without oxygen precipitation, so as to control oxygen precipitation and prepare high-performance monocrystalline silicon materials.

In the prior art, the annealing process (such as the three-step annealing method of Czochralski silicon) is generally carried out in the later stage of crystal pulling. After the annealing process, the oxygen impurities near the surface will be volatilized and detached, and the content of oxygen impurities will be greatly reduced; at the same time, the oxygen impurities inside It will coalesce to form oxygen precipitation, and the internal oxygen precipitation can be used as a gettering center to capture metal impurities near the surface, further reducing impurities near the surface and improving the quality of silicon wafers. However, the content of oxygen impurities in single crystal silicon prepared by the Czochralski method is relatively high, and the oxygen impurity content is generally between 5×10 ¹⁷ atom/cm ² and 9×10 ¹⁷ atom/cm ² , and the annealing treatment cannot completely remove the oxygen near the surface. Impurities, the residual oxygen impurity content is generally above 5×10 ¹⁰ atom/cm ² , this content of oxygen impurities may form oxygen precipitated lattice defects in the subsequent process and affect the performance of silicon wafers, reducing the yield of subsequent processes. Rate. For example, in the subsequent process of forming a self-aligned nickel silicide on the surface of a silicon wafer, the existence of oxygen precipitation lattice defects will affect the stability of the nickel silicide phase transition, making the thickness of the formed nickel silicide film layer uneven and the resistance value deviated from Ideal value. As another example, after a subsequent ion implantation process is performed on a silicon wafer containing oxygen-precipitated lattice defects, the surface of the silicon wafer will be greatly damaged, resulting in poor uniformity of the silicon wafer surface. Therefore, it is necessary to find a method to further reduce the content of oxygen impurities and oxygen precipitated lattice defects near the surface of the silicon wafer. Especially for some raw silicon wafers that have not been subjected to high-temperature annealing, the near surface has a high content of oxygen impurities, and it is easier to form oxygen precipitated lattice defects. How to further reduce the oxygen impurities and oxygen precipitated lattices near the surface of the silicon wafer Defect content is an urgent problem.

Contents of the invention

In order to solve the problem that the oxygen impurities and lattice defects existing on the surface of the silicon wafer have adverse effects on the subsequent manufacturing process, the invention provides a method for pretreatment of the silicon wafer.

A kind of silicon wafer pretreatment method provided by the invention comprises the following steps:

Provide silicon wafers, perform nitriding treatment on the silicon wafers, and form a nitrogen-doped modified layer on the surface of the silicon wafers;

Annealing is performed on the silicon wafer after the nitriding treatment.

Preferably, the nitriding process includes a decoupled plasma nitriding process.

Preferably, the process conditions of the decoupled plasma nitriding process include: the radio frequency power is 2200W-2800W, the nitrogen flow rate is 150sccm-250sccm, and the process time is 50s-70s.

Preferably, the annealing process includes a post-nitridation annealing process.

Preferably, the process conditions of the post-nitridation annealing process include: the annealing temperature is 780°C-1000°C, the annealing time is 15s-25s, the annealing atmosphere is nitrogen atmosphere and the nitrogen flow rate is 15sccm-25sccm.

Preferably, the thickness of the modified layer is

Preferably, after the silicon wafer is nitridated, the nitrogen impurity content of the modified layer is 10 ¹² atom/cm ² -10 ¹³ atom/cm ² .

Preferably, after the silicon wafer is annealed, the oxygen impurity content on the surface of the silicon wafer is less than 10 ⁸ atom/cm ² .

Preferably, the silicon chip includes a P-type silicon chip.

Preferably, the silicon wafer is a single crystal silicon wafer.

Compared with the prior art, the silicon chip pretreatment method provided by the invention has the following advantages:

The silicon wafer pretreatment method provided by the present invention can form a nitrogen-doped modification layer on the silicon wafer surface through nitriding treatment. Due to the existence of nitrogen impurities, the oxygen impurity content on the silicon wafer surface can be reduced and the modification layer can be suppressed. The formation of oxygen precipitated lattice defects in the medium; through annealing treatment, further remove the oxygen impurities on the surface of the silicon wafer, and repair the surface lattice defects, and finally obtain a silicon wafer with the content of surface oxygen impurities and oxygen precipitated lattice defects in line with expectations. Therefore, the silicon wafer pretreatment method provided by the present invention can effectively reduce the content of oxygen impurities and oxygen precipitated lattice defects on the surface of the silicon wafer, thereby improving the yield rate of subsequent manufacturing processes.

Description of drawings

Fig. 1 is the flow chart of the silicon chip preprocessing method provided by an embodiment of the present invention;

Fig. 2 is a schematic diagram of carrying out nitriding treatment to a silicon wafer in an embodiment of the present invention;

Fig. 3 is the flow chart of the method for phase transition monitoring of nickel silicide in an embodiment of the present invention;

Fig. 4 is the nickel silicide phase transition curve of the silicon wafer obtained by nickel silicide phase transition monitoring in an embodiment of the present invention;

5 is a flow chart of a method for ion implantation monitoring in an embodiment of the present invention;

FIG. 6 is a histogram showing the comparison of surface uniformity of each silicon wafer sample obtained through ion implantation monitoring in an embodiment of the present invention.

Wherein, the reference signs are explained as follows:

10-silicon wafer; 101-modified layer.

detailed description

In order to make the purpose, advantages and features of the present invention clearer, a silicon wafer pretreatment method provided by the present invention will be further described in detail below in conjunction with the accompanying drawings. It should be noted that all the drawings are in a very simplified form and use imprecise scales, and are only used to facilitate and clearly assist the purpose of illustrating the embodiments of the present invention.

Please refer to Fig. 1, a kind of silicon chip preprocessing method provided in the present embodiment comprises the following steps:

Step S1: providing a silicon wafer, performing nitriding treatment on the silicon wafer, and forming a nitrogen-doped modified layer on the surface of the silicon wafer;

Step S2: performing annealing treatment on the silicon wafer after nitriding treatment.

Please refer to FIG. 2 , step S1 is performed to provide a silicon wafer 10 , perform nitriding treatment on the silicon wafer 10 , and form a nitrogen-doped modification layer 101 on the surface of the silicon wafer 10 .

In this embodiment, the silicon wafer 10 provided is preferably an original silicon wafer, and the original silicon wafer is a silicon wafer prepared by an original silicon wafer factory without forming a semiconductor device. The silicon wafer 10 is preferably a single crystal silicon wafer, but is not limited thereto, and may also be a polycrystalline silicon wafer or an amorphous silicon wafer. The silicon chip 10 is preferably a P-type silicon chip. The P-type silicon chip has the advantages of low cost and convenient circuit design, and the impact of impurities or defects on the P-type silicon chip is relatively small, so the P-type silicon chip is widely used in In the manufacture of various semiconductor devices; the silicon wafer 10 is not limited to a P-type silicon wafer, for example, it may also be an N-type silicon wafer.

掺氮的改性层101，所述改性层101的氮杂质含量为10¹²atom/cm²～10¹³atom/cm²。所述硅片10表面氮杂质的引入可以降低其表面的氧杂质含量从而抑制氧沉淀缺陷的形成，同时可改善所述硅片10的机械强度。Nitrogen is a very important impurity in single crystal silicon, which can interact with other electrically active impurities and defects to affect the electrical properties of the material. Nitrogen impurities in silicon will not form precipitates to cause lattice defects, and nitrogen impurities can reduce the content of oxygen impurities to inhibit the formation of oxygen precipitates, and at the same time improve the mechanical strength of silicon wafers. Therefore, nitrogen doping treatment is an important means of modifying silicon wafers, and the nitrogen doping process has also been greatly developed at present. The nitriding treatment preferably adopts a decoupled plasma nitriding (Decouple Plasma Nitride) process, and the decoupled plasma nitriding process can form a uniform distribution at a certain depth on the surface of the silicon wafer by exposing the surface of the silicon wafer to a plasma nitrogen atmosphere. Nitrogen impurities. The decoupled plasma nitriding process can be carried out at room temperature, avoiding the problem of lattice defects caused by high temperature treatment, and this process also has the advantages of energy saving and time saving, and is a common process for nitrogen doping treatment. In order to improve the effect of nitriding treatment, the process conditions of the decoupled plasma nitriding process need to be controlled, for example, the radio frequency power is 2200W-2800W, the nitrogen flow rate is 150sccm-250sccm, and the process time is 50s-70s. The RF power determines the energy of the nitrogen ions generated. The appropriate energy of the nitrogen ions can ensure that the nitrogen ions can enter the surface of the silicon wafer, and at the same time ensure that the nitrogen ions will not enter the internal area under the surface of the silicon wafer. The nitrogen flow rate and process time determine the content of nitrogen impurities in the silicon wafer after the process is completed. In this embodiment, preferably, the radio frequency power is 2500W, the nitrogen gas flow rate is 200sccm, and the process time is 60s. After nitriding treatment is performed under these process conditions, a layer with a thickness of

Nitrogen-doped modified layer 101, the nitrogen impurity content of the modified layer 101 is 10 ¹² atom/cm ² -10 ¹³ atom/cm ² . The introduction of nitrogen impurities on the surface of the silicon wafer 10 can reduce the content of oxygen impurities on the surface to suppress the formation of oxygen precipitation defects, and at the same time improve the mechanical strength of the silicon wafer 10 .

Step S2 is executed to perform annealing treatment on the silicon wafer 10 after the nitriding treatment.

The annealing treatment can stabilize the nitrogen impurities in the modified layer 101 formed in step S1, repair the plasma damage formed during the nitriding treatment, and at the same time repair the original oxygen precipitation defects in the silicon wafer 10 . Preferably, the annealing treatment adopts a post nitriding annealing (Post Nitride Anneal) process, and at the same time, in order to improve the effect of the annealing treatment, the process conditions of the post nitriding annealing process can be controlled, preferably, the annealing temperature The temperature is 780°C-1000°C, the annealing time is 15s-25s, the annealing atmosphere is a nitrogen atmosphere and the nitrogen flow rate is 15sccm-25sccm. In this embodiment, preferably, the annealing temperature is 800°C, the annealing time is 20s, the annealing atmosphere is a nitrogen atmosphere, and the nitrogen flow rate is 20 sccm. After annealing under these process conditions, the nitrogen impurity content of the modified layer 101 Further increase to 10 ¹⁵ atom/cm ² to 5×10 ¹⁵ atom/cm ² . The increase of the nitrogen impurity content can further reduce the oxygen impurity content. For example, in this embodiment, it is determined that the initial surface oxygen impurity content of the silicon wafer 10 is above 5×10 ¹⁰ atom/cm ² . The oxygen impurity content on the surface of the silicon wafer 10 is less than 10 ⁸ atom/cm ² . The reduction of the content of oxygen impurities on the surface of the silicon wafer 10 can further inhibit the formation of lattice defects of oxygen precipitation on the surface.

When there are oxygen-precipitated lattice defects on the surface of the silicon wafer, the following effects will occur:

First, in the salicide process, after metal is deposited on the surface of the silicon wafer, an annealing treatment is performed to form a stable, dense and low-resistance metal silicide (such as nickel silicide) film layer. When there are oxygen precipitation lattice defects on the surface of the silicon wafer, the stability of the formed metal silicide film layer is poor, and its sheet resistance value Rs will deviate from the expected reference value.

In addition, after the ion implantation process is performed, ion implantation monitoring will be performed to evaluate the effect of the ion implantation, that is, to evaluate whether the degree of damage to the surface of the silicon wafer by the ion implantation meets expectations. The ion implantation monitoring usually uses thermal wave measurement (Thermal Wave) to obtain the measured value of surface uniformity representing the degree of surface damage of the silicon wafer, and the effect of ion implantation is evaluated according to the measured value of the surface uniformity. Oxygen precipitated lattice defects existing on the surface of the silicon wafer will affect the measured value of the surface uniformity, thereby affecting the judgment of the ion implantation effect.

After improving the oxygen precipitation lattice defects on the surface of the silicon wafer, the metal silicide formed in the self-aligned metal silicide process and the surface uniformity of the silicon wafer after the ion implantation process will be more ideal.

Therefore, the quality monitoring will be carried out on the silicon wafers pretreated as shown in Figure 1 below, and the effect of the silicon wafer pretreatment method will be described according to the quality monitoring results, and the silicon wafers that have not been pretreated as shown in Figure 1 will be used as a comparative example , it is further illustrated from the comparison results that the silicon wafer pretreatment method has the advantages of reducing the content of oxygen impurities and oxygen precipitated lattice defects on the silicon wafer surface, thereby improving the yield rate of the subsequent manufacturing process.

)的镍金属薄膜；进行退火处理形成镍硅化物，退火过程中逐渐形成稳定的镍硅化物，同时测量退火过程中镍硅化物的相变曲线；根据所述相变曲线评估退火处理完成后形成的镍硅化物的稳定性。在退火处理步骤中会形成镍硅化物的各种相(主要包括NiSi相和NiSi₂相)的混合相，并且随着退火处理的进行，镍硅化物的各种相之间会发生相转变。当硅片表面无晶格缺陷或晶格缺陷很少且退火条件控制良好时，退火过程中镍硅化物的各种相会逐渐形成单一的电阻值低的NiSi相，最终生成致密且稳定的镍硅化物薄膜。当硅片表面晶格缺陷含量较大时，由于形成镍硅化物和镍硅化物相转变这两个过程均是发生在硅片表面与镍金属层或硅片表面与镍硅化物之间的界面处，存在于硅片表面的晶格缺陷会影响镍硅化物形成过程和镍硅化物相转变过程，导致退火后的镍硅化物薄膜多相混合、均匀度差且电阻值偏离预期。测量所述镍硅化物的相变曲线的方法包括：在整个退火过程中，测量若干个不同温度下的镍硅化物的方块电阻值Rs，并得到方块电阻值Rs随温度的变化曲线，此变化曲线即为镍硅化物的相变曲线。The quality monitoring includes nickel silicide phase change monitoring and ion implantation monitoring. Please refer to Fig. 3, the method flow process of described nickel silicide phase change monitoring can briefly describe as follows: provide the silicon chip to be monitored; Deposit a certain thickness on the surface of the silicon chip to be monitored (for example

) nickel metal thin film; perform annealing treatment to form nickel silicide, gradually form stable nickel silicide in the annealing process, measure the phase transition curve of nickel silicide in the annealing process simultaneously; Stability of nickel silicides. A mixed phase of various phases of nickel silicide (mainly including NiSi phase and NiSi ₂ phase) is formed during the annealing treatment step, and as the annealing process progresses, phase transitions occur among the various phases of nickel silicide. When there are no or few lattice defects on the surface of the silicon wafer and the annealing conditions are well controlled, the various phases of nickel silicide will gradually form a single NiSi phase with low resistance value during the annealing process, and finally produce dense and stable nickel. Silicide film. When the content of lattice defects on the surface of the silicon wafer is large, the two processes of formation of nickel silicide and nickel silicide phase transition both occur at the interface between the surface of the silicon wafer and the nickel metal layer or the surface of the silicon wafer and the nickel silicide The lattice defects existing on the surface of the silicon wafer will affect the formation process of nickel silicide and the phase transition process of nickel silicide, resulting in heterogeneous mixing of the nickel silicide film after annealing, poor uniformity and deviation from the expected resistance value. The method for measuring the phase transition curve of the nickel silicide includes: measuring the sheet resistance Rs of the nickel silicide at several different temperatures during the entire annealing process, and obtaining the change curve of the sheet resistance Rs with temperature, the change The curve is the phase transition curve of nickel silicide.

Fig. 4 shows the phase transition curve of the nickel silicide of the silicon wafer, wherein curve A is the phase transition curve of the nickel silicide of the comparison silicon wafer, and the silicon wafer provided in step S1 of the comparison silicon wafer and Fig. 1 belongs to the same manufacturer , the same batch and the same specifications, and the comparison silicon wafer has not been pretreated as shown in Figure 1; Curve B is the phase transition curve of the nickel silicide of the pretreated silicon wafer, and the pretreated silicon wafer is compared with the comparison Compared with silicon wafers, the pretreatment shown in Figure 1 is added; Curve C is the ideal phase transition curve of nickel silicide. The ideal phase transition curve corresponds to the phase transition curve of the nickel silicide completely forming a low-resistance NiSi phase during the annealing process and finally forming a stable and dense nickel silicide film under ideal initial conditions (silicon wafer surface defect content meets expectations); The ideal phase transition curve is formed from empirical data published in the industry, and is a benchmark curve characterizing the stability of nickel silicide formed in the salicide process. The annealing conditions corresponding to the curve A, curve B and curve C are the same. For example, in this embodiment, the annealing conditions include: the annealing temperature is 300° C., and the annealing time is 25 s.

From the comparison of the curves in Fig. 4, it can be concluded that the phase transition curve of the nickel silicide of the comparison silicon wafer deviates from the ideal phase transition curve and the overall sheet resistance Rs is higher than that of the ideal phase transition curve. , the quality of the nickel silicide film layer formed on the surface of the comparison silicon wafer is poor, and the quality of the comparison silicon wafer cannot even meet the monitoring requirements. The main reason is that the comparative silicon wafer has not been pretreated, and the oxygen lattice defects on its surface affect the nickel silicide phase transition process. From the comparison of each curve in Fig. 4, it can also be concluded that the phase transition curve of the nickel silicide of the pretreated silicon wafer meets the ideal phase transition curve, indicating that the pretreated silicon wafer has formed a stable, compact, low-resistance nickel The silicide film also indirectly indicates that the content of lattice defects on the surface of the pretreated silicon wafer is in line with expectations and that the lattice defects will not adversely affect the phase transition of nickel silicide.

Therefore, the silicon wafer pretreatment method provided in this embodiment can reduce the oxygen precipitation lattice defects on the surface of the silicon wafer, thereby ensuring the formation of a stable, dense, and low-resistance nickel silicide film in the salicide process. .

The above-mentioned ion implantation monitoring refers to the detection and characterization of the uniformity of the silicon wafer surface after the ion implantation process, so as to evaluate the damage degree of the ion implantation process to the silicon wafer surface. In the prior art, the uniformity of the silicon wafer surface is generally measured by thermal wave measurement. The thermal wave measurement mainly measures the reflectivity of each area on the silicon wafer surface, and the change of the reflectance of each area can reflect the uniformity of the silicon wafer surface. The lattice defects existing on the surface of the silicon wafer will affect the reflectivity measured by the thermal wave, and then affect the judgment of the ion implantation effect. Please refer to Fig. 5, the method flow of the ion implantation monitoring can be briefly described as follows: provide the silicon wafer to be monitored; perform ion implantation on the silicon wafer to be monitored; perform thermal wave measurement on the silicon wafer after ion implantation; The measurement results calculate the uniformity of the silicon wafer surface and evaluate the effect of ion implantation.

The thermal wave measurement is generally carried out by a thermal wave measuring instrument, which emits a low-energy laser to irradiate the sample area on the surface of the silicon wafer to be measured, and part of the laser light will be reflected from the surface of the silicon wafer to be measured, and will be detected by a detector. The reflected laser, that is, the reflected light, then obtains the reflectance; the reflectance corresponding to multiple sample areas of the same silicon wafer is measured, and the surface uniformity of the silicon wafer is calculated according to the reflectance corresponding to the multiple sample areas. The surface uniformity is defined as the standard deviation of the reflectances corresponding to the multiple sample areas, and the standard deviation can reflect the degree of dispersion among the reflectances, so the surface uniformity can be evaluated by the standard deviation. It should be noted that, when the surface uniformity is smaller (or closer to 0), it means that the corresponding surface is more uniform; on the contrary, when the surface uniformity is larger, it means that the corresponding surface is more uneven.

FIG. 6 is a histogram showing the comparison of surface uniformity of each silicon wafer sample obtained by ion implantation monitoring. The surface uniformity data of 12 silicon wafer samples are shown in Fig. 6, and these 12 silicon wafer samples are the original silicon wafers of the same batch prepared by the same silicon wafer factory, wherein 9 silicon wafer samples (silicon wafer 1, Silicon wafer 2 ... silicon wafer 9) are pretreated silicon wafers, through the pretreatment shown in Figure 1; the remaining 3 silicon wafer samples (silicon wafer 11, silicon wafer 12 and silicon Tablet 13) was used as a comparative example. The dotted line in Figure 6 is the specification line, and the ordinate value corresponding to the dotted line is the specification value. When the surface uniformity of the silicon wafer is greater than the specification value, it means that the surface uniformity of the silicon wafer is poor and cannot meet the specification standard. When the surface uniformity of the silicon wafer is less than this specification value, it means that the surface uniformity of the silicon wafer is better and meets the specification standard. The specification value can be determined according to the quality standard of the actual ion implantation process. In this embodiment, the specification value is set to 1.5, which is a commonly used specification value in the industry. It can be seen from Fig. 6 that the surface uniformity of the comparative examples (silicon wafer 11, silicon wafer 12 and silicon wafer 13) all exceeds the specification value, and it can be judged that the ion implantation has relatively large damage to the surface of the silicon wafer, and the surface uniformity of the silicon wafer is relatively large. The damage is serious, and the effect of ion implantation is relatively poor; and the surface uniformity of the pretreated silicon wafers (silicon wafer 1, silicon wafer 2 ... silicon wafer 9) is all less than the specification value, so it can be judged that ion implantation has a negative effect on silicon The wafer surface was less damaged, the surface uniformity of the silicon wafer was as expected, and the effect of ion implantation was good. It should be noted that the measured value of the surface uniformity of the comparative example may not reflect the real surface uniformity, and defects such as oxygen precipitation on the surface of the comparative example will affect the measured value of the reflectivity and thus make the measured value of the uniformity higher . However, in the prior art, the surface uniformity of the silicon wafer and the effect of ion implantation are generally evaluated through the measured value of the surface uniformity. Therefore, for silicon wafers with oxygen precipitated lattice defects on the surface, the surface is more likely to be damaged during ion implantation, and the measured value of the surface uniformity will be higher.

Therefore, the silicon wafer pretreatment method provided in this embodiment can reduce the oxygen precipitated lattice defects on the surface of the silicon wafer, thereby avoiding the influence of oxygen precipitated lattice defects on ion implantation monitoring and ion implantation monitoring in the subsequent ion implantation process. Evaluation of Injection Effects.

In summary, the silicon wafer pretreatment method provided by the present invention can form a nitrogen-doped modified layer on the silicon wafer surface through nitriding treatment, and the presence of nitrogen impurities can inhibit the precipitation of oxygen in the modified layer. The formation of defects; through annealing treatment, the oxygen impurities on the surface of the silicon wafer are further removed, and the lattice defects on the surface are repaired, and finally a silicon wafer with the content of oxygen impurities on the surface and the number of oxygen precipitated lattice defects is in line with the expectation. The metal silicide phase change monitoring and ion implantation monitoring on the pretreated silicon wafer further illustrate the effect of the silicon wafer pretreatment method on improving the quality of the silicon wafer and thus improving the yield rate of the subsequent process. Therefore, the silicon wafer pretreatment method provided by the present invention can effectively reduce the content of oxygen impurities and oxygen precipitated lattice defects on the surface of the silicon wafer, thereby improving the yield rate of subsequent manufacturing processes.

In addition, it can be understood that although the present invention has been disclosed above with preferred embodiments, the above embodiments are not intended to limit the present invention. For any person skilled in the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or be modified to be equivalent to equivalent changes. Example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention, which do not deviate from the technical solution of the present invention, still fall within the protection scope of the technical solution of the present invention. Furthermore, it is to be understood that this invention is not limited to the particular methods, compounds, materials, fabrication techniques, usages and applications described herein, which may vary. It should also be understood that the terminology described herein is used to describe particular embodiments only and is not intended to limit the scope of the present invention. It must be noted that as used herein and in the appended claims, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a step" means reference to one or more steps, and may include sub-steps. All conjunctions used should be understood in their broadest sense. Therefore, the word "or" should be understood as having a definition of logical "or", rather than a logical "exclusive or", unless the context clearly expresses the contrary meaning. Structures described herein are to be understood as also referring to functional equivalents of the structures. Language that may be construed as approximation should be construed as such, unless the context clearly dictates otherwise.

Claims (10)

1. A silicon wafer pretreatment method is characterized by comprising the following steps:

providing a silicon wafer, performing nitridation treatment on the silicon wafer, and forming a nitrogen-doped modified layer on the surface of the silicon wafer;

and annealing the silicon wafer subjected to the nitriding treatment.

2. The method of pre-treating a silicon wafer according to claim 1, wherein the nitriding process comprises a decoupled plasma nitriding process.

3. The silicon wafer pretreatment method of claim 2, wherein the process conditions of the decoupled plasma nitridation process comprise: the radio frequency power is 2200W-2800W, the nitrogen flow is 150 sccm-250 sccm, and the process time is 50 s-70 s.

4. The method for pretreating a silicon wafer according to claim 1, wherein the annealing process comprises a post-nitridation annealing process.

5. The silicon wafer pretreatment method according to claim 4, wherein the process conditions of the post-nitridation annealing process include: the annealing temperature is 780-1000 ℃, the annealing time is 15-25 s, the annealing atmosphere is nitrogen atmosphere, and the nitrogen flow is 15-25 sccm.

6. The method for pretreating silicon wafers according to claim 1, wherein the thickness of the modification layer is

7. The silicon wafer pretreatment method according to claim 1, wherein the nitrogen impurity content of said modified layer after said silicon wafer is subjected to nitriding treatment is 10 ¹² atom/cm ² ～10 ¹³ atom/cm ² 。

8. The method for pretreating silicon wafer according to claim 1, wherein the silicon wafer has an oxygen impurity content of less than 10 on the surface thereof after annealing ⁸ atom/cm ² 。

9. The silicon wafer pretreatment method according to claim 1, wherein the silicon wafer comprises a P-type silicon wafer.

10. The method for pretreating a silicon wafer according to claim 1, wherein the silicon wafer comprises a single-crystal silicon wafer.

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