Method for preparing passivation contact structure based on popaid method and manufacturing method of photovoltaic cell

Abstract

The invention relates to the technical field of photovoltaic cells, and discloses a method for preparing a passivation contact structure based on a popaid method and a manufacturing method of a photovoltaic cell. The preparation method of the passivation contact structure comprises the following steps: preparing a tunneling oxide layer and doped amorphous silicon on the back surface of a silicon wafer by adopting a popaid method; the doping amount of the doping gas for preparing the doped amorphous silicon is 300 to 500 sccm; at least one furnace tube in the tubular annealing machine is used as a pre-annealing tube to pre-anneal the silicon wafer, the pre-annealing temperature is 400-450 DEG C, and the total time is 10-30 min; then the remaining furnace tube in the tubular annealing machine is used as an annealing tube to carry out annealing treatment on the silicon wafer, the annealing temperature is 840-900 DEG C, and the total time is 60-120 min; and obtaining the passivated contact structure. According to the preparation method, high-doping-amount preparation of doped amorphous silicon by a popaid method can be realized, membrane explosion can be avoided, and tubular annealing capacity can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of photovoltaic cells, and in particular to a method for preparing a passivation contact structure based on a popaid method and a method for manufacturing a photovoltaic cell. Background Art

[0002] For N-type TOPCon cells (a type of photovoltaic cell), there are three common methods in the industry for preparing the tunneling oxide layer (tox) and N+ doped polysilicon (N+poly) on the back side: 1. Low Pressure Chemical Vapor Deposition (LPCVD); 2. Plasma enhanced Chemical Vapor Deposition (PECVD); 3. Plasma Oxidation & Plasma Assisted Insitu-doping Deposition (popaid).

[0003] Among them, the popaid method realizes the integrated deposition of the tunneling oxide layer and the N+ doped polysilicon layer in the core structure of the TOPCon battery, and achieves a laboratory conversion efficiency of up to 26.7%; and no additional cleaning and plating process is required, which simplifies the process, effectively reduces the reverse leakage current of the battery, and ensures the hot spot resistance reliability of the TOPCon battery product; therefore, it has a good application prospect.

[0004] However, when the popaid method is used to prepare the tunneling oxide layer and doped amorphous silicon on the back, it is not easy to increase the doping amount of the doped amorphous silicon, which is generally between 1 and 2E+20 cm -3 If the doping amount of doped amorphous silicon is further increased, the film will burst after subsequent high-temperature annealing. This is because: increasing the doping amount of doped amorphous silicon is usually achieved by increasing PH3, because a higher doping amount of PH3 during film coating will increase the hydrogen content in the film layer, resulting in a higher hydrogen content in the film layer. Therefore, during subsequent high-temperature annealing, excessive hydrogen will be quickly released, causing the film layer to be lifted up to form small bubbles, which will lead to film bursting.

[0005] However, the prior art, as shown in CN110165017A, proposes a rapid annealing method for preparing a tunneling oxygen passivation contact structure, which includes the steps of preheating, hydrogen release, crystallization, and cooling, and is compared with the traditional tubular electric furnace annealing. However, this rapid annealing method is only applicable to rapid annealing equipment, and the rapid annealing equipment and the equipment used for tubular electric furnace annealing (i.e., tubular annealing machine) are two different types of annealing equipment, so this rapid annealing method cannot be applied to the tubular annealing machine. Moreover, although the process time of this rapid annealing method is very short; however, the battery cells prepared by this rapid annealing method still have the defect of low filling factor, resulting in a conversion efficiency that is always lower than that of tubular electric furnace annealing, so it is still not used in large quantities on the production line.

[0006] In addition, the tubular electric furnace annealing method mentioned in Example 1 of the specification of the rapid annealing method (as shown in CN110165017A) also has the following defects: first, the annealing temperature of this tubular electric furnace annealing method starts from 600°C, and it is difficult to prevent film explosion when annealing starts at this temperature (especially after the preparation of doped amorphous silicon with a high doping amount such as the popaid method, if this tubular electric furnace annealing method is used, it will be even more difficult to avoid film explosion defects); second, the low-temperature annealing step and the subsequent high-temperature annealing step of this tubular electric furnace annealing method are both carried out in the same furnace tube of a tubular annealing machine, and integrating the low-temperature annealing step and the high-temperature annealing step in the same furnace tube will result in a very slow heating and cooling speed, a very long process time, and low production capacity.

[0007] As for the annealing process for reducing polysilicon doping explosion disclosed in publication number CN115995508A, although this annealing process can reduce explosion by strictly controlling process parameters such as temperature, pressure, nitrogen filling flow rate, etc., this annealing process still has the following defects: after preparing doped amorphous silicon with ultra-high doping amount such as the popaid method, if this annealing process is used, explosion still exists (that is, it is still difficult to avoid explosion for the film layer with high doping amount); on the other hand, steps S1 to S7 of the annealing process are also carried out in the same furnace tube, which will result in a very slow heating and cooling speed, a long process time, and low production capacity. Summary of the invention

[0008] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a method for preparing a passivation contact structure based on a popaid method and a method for manufacturing a photovoltaic cell.

[0009] Based on this, the present invention discloses a method for preparing a passivation contact structure based on a popaid method, comprising the following preparation steps:

[0010] S21, using the popaid method to sequentially prepare a tunneling oxide layer and doped amorphous silicon on the back side of the silicon wafer; wherein the doping amount of the doping gas used to prepare the doped amorphous silicon is 300-500 sccm;

[0011] S22, pre-annealing process: using at least one furnace tube in the tubular annealing machine as a pre-annealing tube to pre-anneal the silicon wafer, the pre-annealing temperature is 400-450° C., and the total pre-annealing time is 10-30 minutes;

[0012] S23, annealing process: the remaining furnace tubes in the tubular annealing machine are used as annealing tubes to anneal the silicon wafers. The annealing temperature is 840-900° C. and the total annealing time is 60-120 min. Thus, a passivation contact structure containing a tunneling oxide layer and doped polysilicon is obtained.

[0013] Preferably, step S21 includes:

[0014] S211, firstly placing the silicon wafer in a plasma oxidation chamber of a popaid device to deposit a tunneling oxide layer on the surface of the silicon wafer;

[0015] S212, placing the silicon wafer in a magnetron sputtering chamber of a popaid device to deposit doped amorphous silicon on the surface of the tunneling oxide layer.

[0016] Further preferably, the deposition process of step S211 is: the belt speed in the plasma oxidation chamber is 2-4 m / min, the temperature is 250-350°C, the pressure is 6-10 Pa, the O2 flow rate is 200-600 sccm, and the back side of the silicon wafer is oxidized using a linear plasma with a power of 40-80 W to deposit the tunneling oxide layer on the surface of the silicon wafer.

[0017] More preferably, in the step S211, a linear plasma with a power of 60 W is used to oxidize the back side of the silicon wafer.

[0018] Further preferably, the deposition process of step S212 is: the belt speed in the magnetron sputtering chamber is 2-4 m / min, the temperature is 200-400° C., the pressure is 0.5-2 pa, a pure silicon target is used, the Ar flow rate is 500-1500 sccm, the doping gas is a mixture of argon and phosphine, and the volume concentration of phosphine in the mixture is less than or equal to 10%, so as to deposit the doped amorphous silicon with a high doping amount on the surface of the tunneling oxide layer.

[0019] More preferably, in the step S212, the volume concentration of the phosphine in the mixed gas is 9%; and the doping amount of the doping gas is 400 sccm.

[0020] Further preferably, in step S23, the doping concentration of the doped polysilicon is equal to or greater than 3.2E+20cm -3 .

[0021] Preferably, the tubular annealing machine comprises five furnace tubes, one of which serves as the pre-annealing tube, and the remaining four furnace tubes serve as the annealing tubes.

[0022] Further preferably, in step S23, the annealing temperature is greater than or equal to 880° C., and the total annealing time is less than or equal to 90 min.

[0023] The method for preparing a passivation contact structure of the present invention is suitable for coating of popaid devices (i.e., coating of a tunneling oxide layer and coating of amorphous silicon with a high doping amount). After coating of amorphous silicon with a high doping amount by popaid devices, the doped amorphous silicon has a high hydrogen content. Therefore, after coating by the popaid method, the present invention firstly performs a pre-annealing process at 400-450°C to slowly release the excess hydrogen, and then performs a subsequent annealing process at 840-900°C to effectively avoid film explosion. In this way, the present invention firstly deposits a tunneling oxide layer and amorphous silicon with a high doping amount by the popaid method in an integrated manner, and then sequentially cooperates with a pre-annealing process at 400-450°C and a subsequent annealing process at 840-900°C; in this way, while increasing the doping amount when preparing doped amorphous silicon by the popaid method to achieve a higher doping concentration of doped polysilicon, it can also effectively avoid film explosion, thereby improving the conversion efficiency of photovoltaic cells.

[0024] Moreover, compared with the existing annealing process (such as the tubular electric furnace annealing method of Comparative Example 1 shown in CN110165017A), since the annealing process of the above step S23 of the present invention (taking Example 2 as an example) increases the annealing temperature and reduces the total time of the annealing process, and the pre-annealing process and the annealing process are both performed in the same tubular annealing machine using different furnace tubes (one furnace tube in the tubular annealing machine is specifically used for pre-annealing, and the remaining four furnace tubes are specifically used for annealing process), the overall annealing capacity of the tubular annealing machine is further improved.

[0025] The present invention also discloses a method for manufacturing a photovoltaic cell, comprising the following steps:

[0026] S1, preparing a selective emitter on the front side of the silicon wafer after texturing, and sequentially cleaning the silicon wafer with a single-side HF solution and an alkaline solution;

[0027] S2. Using the method for preparing a passivation contact structure based on the popaid method as described in any one of claims 1 to 9, to prepare the passivation contact structure containing a tunneling oxide layer and doped polysilicon on the back side of a silicon wafer;

[0028] S3, then sequentially clean the silicon wafer, deposit front and back passivation films, prepare metal electrodes and inject light to obtain a photovoltaic cell.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] The method for preparing a passivated contact structure of the present invention prepares a tunneling oxide layer and doped amorphous silicon by a popaid method, a pre-annealing process at 400-450°C and a subsequent annealing process at 840-900°C; it can not only realize the preparation of doped amorphous silicon with a high doping amount by the popaid method, but also avoid film explosion, thereby improving the conversion efficiency of photovoltaic cells; compared with the existing annealing process (such as the tubular electric furnace annealing method of comparative example 1 shown in CN110165017A), it can also improve the production capacity of tubular annealing.

[0031] According to the test, the doping concentration of the doped polysilicon prepared by the present invention can be increased from 1.1E+20cm -3 Increased to 3.2E+20cm -3 And above, it suppressed the film bursting defect under the high doping amount of the popaid method, reducing the film bursting rate from 100% to 0%; it also reduced the N+ contact resistivity on the back of the photovoltaic cell, and improved the implicit open circuit voltage, open circuit voltage and fill factor of the photovoltaic cell, and the conversion efficiency of the photovoltaic cell was increased by 0.11%. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a schematic diagram of the cross-sectional structure of a photovoltaic cell prepared in Example 1 of the present invention.

[0033] Figure 2 The following are appearance diagrams of the silicon wafers after the annealing process of Example 2 and Comparative Example 1.

[0034] Figure 3 This is a 100-fold microscope magnification of the silicon wafer after the annealing process of Example 2 and Comparative Example 1.

[0035] Explanation of the accompanying drawings: front metal electrode 1; front silicon nitride film 2; aluminum oxide film 3; P+ boron diffused emitter 4; P++ heavily doped region 5; N-type single crystal silicon 6; tunneling oxide layer 7; N+ phosphorus-doped polysilicon 8; back silicon nitride film 9; back metal electrode 10. DETAILED DESCRIPTION

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] Example 1

[0038] A photovoltaic cell with a passivated contact structure prepared by the popaid method in this embodiment (see Figure 1 ), comprising the following steps:

[0039] Step S1, pre-treating a silicon wafer to obtain a silicon wafer with a passivation contact structure to be prepared.

[0040] In step S1, taking N-type TOPCon battery as an example, its pre-treatment process includes the following processing steps:

[0041] Step S11, performing texturing treatment on the silicon wafer.

[0042] Step S12, perform boron doping diffusion and laser selective doping on the front side of the silicon wafer in sequence to prepare a selective emitter (including a P+ boron diffused emitter 4 and a P++ heavily doped area 5) on the front side of the silicon wafer; then perform oxidation treatment on the silicon wafer to obtain a better PN junction on the front side of the silicon wafer, and combine with a subsequent cleaning process to remove part of the damaged layer on the surface of the silicon wafer.

[0043] Step S13, cleaning the back side of the silicon wafer with HF solution on one side to remove the borosilicate glass formed on the back side due to the diffusion of boron doping; and then cleaning the silicon wafer with alkaline solution to achieve polishing of the back side of the silicon wafer.

[0044] The silicon wafer is preferably N-type single crystal silicon 6. The above steps S11 to S13 may be specifically referred to the existing preparation process of N-type TOPCon cells, so they will not be described in detail here.

[0045] Step S2. After step S1, a passivation contact structure is prepared on the back side of the silicon wafer processed in step S1 based on the popaid method; wherein the popaid equipment used in the popaid method includes a po chamber (i.e., a plasma oxidation chamber) and a paid chamber (i.e., a magnetron sputtering chamber).

[0046] In step S2, the method for preparing a passivation contact structure based on the popaid method includes the following preparation steps:

[0047] Step S21, using the popaid method to sequentially deposit a tunneling oxide layer 7 and a high doping amount on the back of the silicon wafer to prepare doped amorphous silicon, which specifically includes the following steps:

[0048] Step S211, place the silicon wafer in a po chamber (i.e., plasma oxidation chamber), the belt speed in the po chamber is 2-4m / min, the temperature is 250-350°C, the pressure is 6-10Pa, the O2 flow rate is 200-600sccm, and the back side of the silicon wafer is oxidized using linear plasma with an oxidation power of 40-80W to obtain a tunneling oxide layer 7 on the back side of the silicon wafer.

[0049] Step S212, placing the silicon wafer in a paid chamber (i.e., a magnetron sputtering chamber), the belt speed in the paid chamber is 2-4m / min, the temperature is 200-400℃, the pressure is 0.5-2pa, using pure silicon target material, Ar flow rate is 500-1500sccm, the total flow rate of the mixture of PH3 and Ar (9% PH3+91Ar mixture) is 300-500sccm, so as to prepare doped amorphous silicon with a high doping amount on the back side of the tunnel oxide layer 7.

[0050] After the popaid process of step S21, the silicon wafer is first subjected to a pre-annealing process of step S22, and then subjected to an annealing process of step S23, to obtain a passivation contact structure including a tunneling oxide layer 7 and doped polysilicon prepared with a high doping amount. The doped polysilicon obtained in this embodiment is specifically N+ phosphorus-doped polysilicon 8.

[0051] The pre-annealing process of step S22 and the annealing process of step S23 are both performed in the same tubular annealing machine. Moreover, like the existing tubular annealing machine, the tubular annealing machine used in step S22 and step S23 includes a plurality of furnace tubes, such as five furnace tubes.

[0052] Step S22, pre-annealing process: placing the silicon wafer in a tubular annealing machine, and using at least one furnace tube in the tubular annealing machine as a pre-annealing tube to pre-anneal the silicon wafer, the pre-annealing temperature is 400-450°C, and the total time is 10-30 minutes.

[0053] Step S23, annealing process: the remaining furnace tube in the tubular annealing machine is used as an annealing tube to anneal the silicon wafer, and the annealing temperature is 840-900°C (preferably 880-890°C, and more preferably 890°C), so that the doped amorphous silicon is crystallized at high temperature to form doped polysilicon, and the doped polysilicon obtains more activated doping amount to obtain doped polysilicon with a high doping concentration; at the same time, the total time of the annealing process is 60-120 minutes, and the total time of the annealing process is appropriately shortened to avoid the doped atoms diffusing too deeply inward at high temperature to affect the passivation performance of the passivation contact structure.

[0054] The pre-annealing process of step S22 and the annealing process of step S23 are performed in the same tubular annealing machine. Taking the tubular annealing machine including five furnace tubes as an example, preferably, the pre-annealing process uses one furnace tube in the tubular annealing machine, and the annealing process uses the remaining four furnace tubes (these four furnace tubes can anneal four silicon wafers respectively); in this way, the tubular annealing machine can automatically start one furnace tube for pre-annealing and automatically start the remaining four furnace tubes for annealing.

[0055] Step S3, the silicon wafer processed in step S2 is cleaned, a front and back passivation film is deposited, a metal electrode is prepared, and a light injection post-processing process is performed to obtain a photovoltaic cell. The structure of the photovoltaic cell is shown in FIG. Figure 1 .

[0056] In step S3, taking the N-type TOPCon battery as an example, its front passivation film includes an aluminum oxide film 3 and a front silicon nitride film 2 deposited in sequence, and the back passivation film includes a back silicon nitride film 9; preparing the metal electrode includes first patterning and printing the metal paste, and then sintering to form a metal electrode (the metal electrode is divided into a front metal electrode 1 and a back metal electrode 10).

[0057] In step S3, the light injection mainly plays the role of hydrogen passivation.

[0058] The details of the above step S3 can be found in the existing preparation process of N-type TOPCon battery, so it will not be described in detail here.

[0059] Example 2

[0060] The present embodiment is a method for preparing a photovoltaic cell with a passivated contact structure based on the popaid method. The manufacturing steps are similar to those of the embodiment 1. The difference between the embodiment 1 and the embodiment 1 is as follows:

[0061] In step S211, the belt speed in the po chamber is 3m / min, the temperature is 300°C, the pressure is 8Pa, the O2 flow rate is 400sccm, and the back of the silicon wafer is oxidized using linear plasma with an oxidation power of 60W to form a tunneling oxide layer 7 on the back of the silicon wafer.

[0062] In step S212, the belt speed in the paid chamber is 3m / min, the temperature is 300℃, and the pressure is 1pa. A pure silicon target is used, the Ar flow rate is 1000sccm, and the total flow rate of the PH3 and Ar mixture (9% PH3+91Ar mixture) is 400sccm, so as to prepare doped amorphous silicon with a high doping amount on the back side of the tunneling oxide layer 7.

[0063] In step S22, the pre-annealing temperature is 400°C and the total time is 20 minutes (10 minutes at a constant temperature).

[0064] In step S23, the annealing temperature is 880°C and the total time is 90 minutes (20 minutes at a constant temperature).

[0065] Comparative Example 1

[0066] The manufacturing method of a photovoltaic cell with a passivated contact structure based on the popaid method in this comparative example has the same manufacturing steps as those in Example 2, and the difference between the manufacturing method and Example 2 is as follows:

[0067] After step S21 , the pre-annealing process of step S22 is omitted, and the annealing process of step S23 is directly performed.

[0068] Comparative Example 2

[0069] The present comparative example is a method for preparing a photovoltaic cell with a passivated contact structure based on the popaid method. The preparation steps thereof refer to the comparative example 1. The difference between the comparative example 1 and the comparative example 1 is as follows:

[0070] In step S212, the total flow rate of the mixed gas of PH3 and Ar (mixed gas of 9% PH3+91Ar) is 225sccm, and the other parameters are referred to comparative example 1, thereby obtaining the passivation contact structure of this comparative example including a tunneling oxide layer and low-doped polysilicon.

[0071] Performance Testing

[0072] 1. Comparison of annealing capacity between the annealing process in step S23 of Example 2 and the existing annealing process (such as the tubular electric heating furnace annealing method of Comparative Example 1 shown in CN110165017A).

[0073] Table 1

[0074]

[0075] Compared with the existing annealing process (such as the tubular electric furnace annealing method of comparative example 1 shown in CN110165017A), since the annealing process of the above step S23 of the present invention (taking Example 2 as an example) increases the annealing temperature and reduces the total time of the annealing process, and the pre-annealing process and the annealing process are both performed in the same tubular annealing machine using different furnace tubes (one furnace tube in the tubular annealing machine is specifically used for pre-annealing, and the remaining four furnace tubes are specifically used for annealing process), the overall annealing capacity of the tubular annealing machine is also improved (as shown in Table 1 below).

[0076] 2. The performance of the silicon wafers after annealing process of Example 2 and Comparative Examples 1-2 was tested, and the test results are shown in Table 2 below.

[0077] In Table 2, the peak concentration of the doping of the N-type doped polysilicon is obtained by performing an electrochemical capacitance voltage (ecv) test on the doped polysilicon on the back side of the silicon wafer after the annealing process and the cleaning in step S3.

[0078] Table 2

[0079]

[0080] Combined with Table 2 and Figure 2-3 , we can know that:

[0081] Example 2 By depositing a tunnel oxide layer (and appropriately increasing the thickness of the tunnel oxide layer to prevent excessive diffusion of phosphorus into N-type single crystal silicon) and preparing doped amorphous silicon with a high doping amount, the pre-annealing process and the annealing process can be combined to obtain doped polysilicon with a high doping concentration, thereby increasing the doping concentration of the doped polysilicon to 3.2E+20cm -3 It can be seen that after the high-doping amount of doped amorphous silicon is prepared, the pre-annealing process can play a good role in releasing hydrogen and avoid the film explosion during the annealing process after the high-doping amount of doped amorphous silicon is prepared.

[0082] In contrast, in Comparative Example 1, only high-doping amount doped amorphous silicon is prepared and annealing process is combined (pre-annealing process is omitted), which results in serious film bursting defects.

[0083] In Comparative Example 2, a low-doping amount of doped amorphous silicon is prepared and annealed (the pre-annealing process is omitted). Although the film does not explode, the doping concentration of the doped polysilicon is only 1.1E+20cm -3 , its doping concentration is low.

[0084] 3. The photovoltaic cells of Example 2 and Comparative Example 2 were subjected to performance tests, and the test results are shown in Table 3 below.

[0085] In particular, since the doped polysilicon in Comparative Example 1 had film explosion after step S2, the photovoltaic cell of Comparative Example 1 was not subjected to subsequent performance tests.

[0086] In Table 3, iVoc before printing is the implicit open circuit voltage measured on the silicon wafer before printing the metal paste, N+ contact resistivity is the contact resistivity of the back side of the photovoltaic cell, Eta is the conversion efficiency, Uoc is the open circuit voltage, Isc is the short circuit current, FF is the fill factor, Rs is the series resistance, and Rsh is the parallel resistance.

[0087] Table 3

[0088] Test items Example 2 Comparative Example 2 iVoc / mV before printing 732 730 <![CDATA[N+ Contact Resistivity / mΩ.cm -2 > 1.7 2.1 Number of photovoltaic cell samples / pcs 1800 1800 Eta / % 25.45 25.34 Uoc / V 0.730 0.729 Isc / A 13.86 13.86 FF / % 83.08 82.82 Rs / Ω 0.0011 0.0012 Rsh / Ω 4466 4456

[0089] From Table 3, we can see that:

[0090] Compared with Comparative Example 2, Example 2 prepares doped amorphous silicon with a high doping amount, and cooperates with a pre-annealing process and an annealing process. The photovoltaic cell prepared in Example 2 has a higher iVoc before printing, better passivation performance, and lower back N+ contact resistivity. The cell conversion efficiency Eta is also higher (Eta is 0.11% higher), Uoc is 1mV higher, and FF is 0.26% higher.

[0091] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0092] The technical solution provided by the present invention is introduced in detail above. Specific examples are used in this article to illustrate the principle and implementation mode of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation mode and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for preparing a passivation contact structure based on a popaid method, characterized in that: The method comprises the following preparation steps: S21, using the popaid method to sequentially prepare a tunneling oxide layer and doped amorphous silicon on the back side of the silicon wafer; wherein the doping amount of the doping gas used to prepare the doped amorphous silicon is 300-500 sccm; S22, pre-annealing process: using at least one furnace tube in the tubular annealing machine as a pre-annealing tube to pre-anneal the silicon wafer, the pre-annealing temperature is 400-450° C., and the total pre-annealing time is 10-30 minutes; S23, annealing process: the remaining furnace tubes in the tubular annealing machine are used as annealing tubes to anneal the silicon wafers. The annealing temperature is 840-900° C. and the total annealing time is 60-120 min. Thus, a passivation contact structure containing a tunneling oxide layer and doped polysilicon is obtained.

2. The method for preparing a passivation contact structure based on the popaid method according to claim 1, characterized in that: Step S21 includes: S211, firstly placing the silicon wafer in a plasma oxidation chamber of a popaid device to deposit a tunneling oxide layer on the surface of the silicon wafer; S212, placing the silicon wafer in a magnetron sputtering chamber of a popaid device to deposit doped amorphous silicon on the surface of the tunneling oxide layer.

3. The method for preparing a passivation contact structure based on the popaid method according to claim 2, characterized in that: The deposition process of step S211 is as follows: the belt speed in the plasma oxidation chamber is 2-4 m / min, the temperature is 250-350°C, the pressure is 6-10 Pa, the O2 flow rate is 200-600 sccm, and the back side of the silicon wafer is oxidized using a linear plasma with a power of 40-80 W to deposit the tunneling oxide layer on the surface of the silicon wafer.

4. The method for preparing a passivation contact structure based on the popaid method according to claim 3, characterized in that: In the step S211, a linear plasma with a power of 60 W is used to oxidize the back side of the silicon wafer.

5. The method for preparing a passivation contact structure based on the popaid method according to claim 2, characterized in that: The deposition process of step S212 is as follows: the belt speed in the magnetron sputtering chamber is 2-4 m / min, the temperature is 200-400° C., the pressure is 0.5-2 pa, a pure silicon target is used, the Ar flow rate is 500-1500 sccm, the doping gas is a mixture of argon and phosphine, and the volume concentration of phosphine in the mixture is less than or equal to 10%, so as to deposit the doped amorphous silicon with a high doping amount on the surface of the tunneling oxide layer.

6. The method for preparing a passivation contact structure based on the popaid method according to claim 5, characterized in that: In the step S212, the volume concentration of the phosphine in the mixed gas is 9%; and the doping amount of the doping gas is 400 sccm.

7. A method for preparing a passivation contact structure based on a popaid method according to any one of claims 1 to 6, characterized in that: In step S23, the doping concentration of the doped polysilicon is equal to or greater than 3.2E+20cm -3 .

8. The method for preparing a passivation contact structure based on the popaid method according to claim 1, characterized in that: The tubular annealing machine includes five furnace tubes, one of which is used as the pre-annealing tube, and the remaining four furnace tubes are used as the annealing tubes.

9. A method for preparing a passivation contact structure based on a popaid method according to claim 1 or 8, characterized in that: In step S23, the annealing temperature is greater than or equal to 880°C, and the total annealing time is less than or equal to 90 minutes.

10. A method for manufacturing a photovoltaic cell, characterized in that: The production steps include: S1, preparing a selective emitter on the front side of the silicon wafer after texturing, and sequentially cleaning the silicon wafer with a single-side HF solution and an alkaline solution; S2. Using the method for preparing a passivation contact structure based on the popaid method as described in any one of claims 1 to 9, to prepare the passivation contact structure containing a tunneling oxide layer and doped polysilicon on the back side of a silicon wafer; S3, then sequentially clean the silicon wafer, deposit front and back passivation films, prepare metal electrodes and inject light to obtain a photovoltaic cell.

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