CN114068758B - Boron diffusion treatment control method and device and furnace tube - Google Patents

Abstract

The embodiment of the invention provides a boron diffusion treatment control method and device and a furnace tube, in particular to control the furnace tube to rise from a standby temperature to a deposition temperature; when the temperature of the furnace tube reaches the deposition temperature, carrying out deposition treatment, heating and pushing treatment and high-temperature oxidation treatment on the silicon wafer in the furnace tube; when the furnace tube is controlled to be cooled to the low-temperature oxidation temperature, introducing water vapor with preset pressure and preset steam temperature into the furnace tube by utilizing the bleed air in the process, and continuously presetting the duration; and performing a second cooling operation on the furnace tube so as to reduce the temperature in the furnace tube to the standby temperature. The method solves the problem of low initial doping concentration, namely concentration low head phenomenon in ECV test, by utilizing the difference between water vapor oxidation and conventional dry oxygen, so that the problem of high contact resistance between silicon and metal electrodes is solved, and the P-type doped emitter and the metal electrodes form good ohmic contact, so that the photoelectric conversion efficiency of the silicon cell can be effectively improved.

Description

Boron diffusion treatment control method, device and furnace tube

Technical Field

The invention relates to the field of photovoltaic technology, and in particular to a boron diffusion treatment control method, device and furnace tube.

Background technique

Semiconductor doping technology is an important process step in the field of semiconductor manufacturing. Thermal diffusion is the basic method of semiconductor doping technology. Its principle is to use the thermal motion of molecules in a high-temperature process to disperse one substance between the molecules of another substance. When doping N-type silicon wafers, the conventional boron diffusion method is generally used. The general technical route is: entering the boat -> vacuum -> temperature return -> leak detection -> pre-oxygen -> deposition -> propulsion -> high-temperature and high-oxygen oxidation -> cooling. After the above main steps, the doping of N-type silicon wafers can be completed to obtain the required PN junction.

However, during the post-oxidation process, this technical route will cause the initial concentration of the doped surface to be too low when oxidized at high temperature and high oxygen content, that is, a low-head phenomenon will occur in the ECV test, resulting in a high contact resistance with the metal electrode, which in turn affects the photoelectric conversion efficiency of the silicon cell.

Summary of the invention

In view of this, the present invention provides a boron diffusion process control method, device and furnace tube to improve the photoelectric conversion efficiency of the silicon cell finally formed.

In order to solve the above problems, the present invention discloses a boron diffusion treatment control method, which is applied to furnace tubes. The boron diffusion control method comprises the following steps:

Controlling the furnace tube to heat up from the standby temperature to the deposition temperature;

When the temperature of the furnace tube reaches the deposition temperature, the silicon wafer in the furnace tube is subjected to deposition treatment, temperature-raising treatment and high-temperature oxidation treatment;

After the high-temperature oxidation treatment is performed, the furnace tube is subjected to a first cooling operation to reduce the temperature inside the furnace tube to a low-temperature oxidation temperature. During the first cooling operation on the furnace tube, water vapor with a preset pressure and a preset steam temperature is introduced into the furnace tube by bleed air for a preset time period.

A second temperature reduction operation is performed on the furnace tube to reduce the temperature inside the furnace tube to the standby temperature.

Optionally, the low temperature oxidation temperature is 950-850°C.

Optionally, the bleed gas is oxygen or nitrogen.

Optionally, when the bleed gas is nitrogen, the flow rate of the bleed gas is 3000 sccm, and the flow rate of the water vapor is 2000 sccm.

Optionally, the preset pressure is 600-900 mbar, and the preset steam temperature is 40-80°C.

Optionally, the preset duration is 10 to 40 minutes.

Optionally, the standby temperature is 790-850°C, and the deposition temperature is 850-900°C.

Optionally, the deposition treatment, temperature advancement treatment and high-temperature oxidation treatment of the silicon wafer in the furnace tube include the following steps:

At the deposition temperature, performing a deposition process on the silicon wafer;

After the deposition process is completed, the temperature in the furnace tube is controlled to rise to 990-1050° C., and the silicon wafer is subjected to a temperature-raising and advancing process during the heating process;

The temperature in the furnace tube is controlled to maintain at 990-1050° C., during which dry oxygen is introduced at a flow rate of 8 L/min to full scale to perform high-temperature oxidation treatment on the silicon wafer.

A boron diffusion process control device is also provided, which is applied to a furnace tube and includes at least one processor and a memory, wherein:

The memory is used to store computer programs or instructions;

The processor is used to execute the computer program or instruction so that the boron diffusion processing device performs the boron diffusion processing control method as described above.

A furnace tube is also provided, provided with the boron diffusion treatment control device as described above, and optionally, the furnace tube at least comprises a tube body and a main air inlet pipe arranged at one end of the tube body, and further comprises a boron source air inlet pipe, a nitrogen air inlet pipe, an oxygen air inlet pipe, and a water vapor air inlet pipe respectively connected to the main air inlet pipe;

One end of the water vapor intake pipe is connected to the main intake pipe, and the other end is connected to the steam generating device;

The steam generating device comprises a bottle body for containing deionized water;

The bottle body is also provided with a water injection pipe, an air inlet pipe, a piston and an air outlet.

It can be seen from the above technical scheme that the present invention provides a boron diffusion treatment control method, device and furnace tube, which are applied to the furnace tube, specifically to control the furnace tube to heat up from the standby temperature to the deposition temperature; when the temperature of the furnace tube reaches the deposition temperature, the silicon wafer in the furnace tube is subjected to deposition treatment, temperature promotion treatment and high-temperature oxidation treatment; when the furnace tube is controlled to cool down to the low-temperature oxidation temperature, water vapor with a preset pressure and preset steam temperature is introduced into the furnace tube by bleed air during this process, and the water vapor is continuously introduced for a preset time; the furnace tube is subjected to a second cooling operation to reduce the temperature in the furnace tube to the standby temperature. This scheme utilizes the difference between water vapor oxidation and conventional dry oxygen to solve the problem of too low initial doping concentration caused by the rapid entry of boron atoms doped into the silicon base into the borosilicate glass body due to high-temperature oxidation during the doping process, that is, the concentration depression phenomenon in the ECV test, thereby solving the problem of high contact resistance between silicon and metal electrodes, so that the P-type doped emitter forms a good ohmic contact with the metal electrode, thereby effectively improving the photoelectric conversion efficiency of silicon cells.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

FIG1 is a flow chart of a boron diffusion process control method according to an embodiment of the present application;

FIG2 is a block diagram of a boron diffusion process control device according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a furnace tube according to an embodiment of the present application.

Detailed ways

The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Embodiment 1

FIG. 1 is a flow chart of a boron diffusion process control method according to an embodiment of the present application.

As shown in FIG1 , the boron diffusion treatment method provided in this embodiment is applied to a furnace tube, i.e., a special device for depositing and oxidizing silicon wafers. Specifically, after the furnace tube is put into the boat, the furnace tube is warmed up to stabilize the temperature of the furnace tube; then the furnace tube is vacuumed to complete the leak detection; then a certain amount of oxygen (pre-oxygen) is introduced, which is a step of oxidation before deposition to improve the uniformity of diffusion. After completing the above process, the following boron diffusion treatment steps are performed:

S1. Control the furnace tube to heat up from the standby temperature to the deposition temperature.

The standby temperature here refers to the temperature at which the furnace tube can be charged and unloaded, that is, the temperature at which the silicon wafer is loaded into or taken out of the furnace tube. The standby temperature in this application is preferably 790-850° C. The deposition temperature refers to the temperature at which the silicon wafer is deposited. The deposition temperature in this application is preferably 820-900° C.

S2. Perform deposition treatment, temperature-raising treatment and high-temperature oxidation treatment on the silicon wafers in the furnace tube.

That is, when the temperature in the furnace tube reaches the deposition temperature, the silicon wafer in the furnace tube begins to be subjected to deposition treatment, temperature rise and high temperature oxidation treatment. The specific process is as follows:

First, a boron source and nitrogen are introduced into the furnace tube to perform deposition treatment on the silicon wafer therein;

Then, after the deposition process is completed, the furnace tube is heated up to 950-1000°C so as to perform a temperature-raising process on the silicon wafer;

Finally, when the temperature in the furnace reaches 950-1000°C, the temperature in the furnace is maintained at this temperature, and a dry oxygen flow is introduced into the furnace to perform high-temperature oxidation treatment on the silicon wafer. The flow rate of the dry oxygen flow at this time is 8L/min to full scale.

S3. Performing water vapor oxidation treatment on the silicon wafer that has undergone high temperature oxidation treatment.

That is, after the silicon wafer is subjected to high-temperature oxidation by means of a dry oxygen flow, the furnace tube is subjected to a first cooling operation to reduce the temperature inside the furnace tube to a low-temperature oxidation temperature. The low-temperature oxidation temperature in this embodiment is preferably 950 to 850° C. During this first cooling process, water vapor is introduced into the furnace tube by means of bleed air to perform water vapor oxidation treatment on the surface of the silicon wafer.

The bleed gas here can be oxygen or nitrogen. When nitrogen is used as the bleed gas, the nitrogen flow rate is 3000sccm and the water vapor flow rate is 2000sccm. The water vapor pressure is 600-900mbar and the temperature is 40-80℃. In this way, the furnace tube tension oxidizes the silicon wafer under a slightly negative pressure. This process of water vapor lasts for 10-40 minutes.

S4, performing a second cooling operation on the furnace tube.

After the steam oxidation treatment process is completed, the introduction of steam into the furnace tube is stopped, and then a second cooling operation is performed to reduce the temperature in the furnace tube to the standby temperature for discharge.

It can be seen from the above technical scheme that this embodiment provides a boron diffusion control method, which is applied to the furnace tube, specifically controlling the furnace tube to heat up from the standby temperature to the deposition temperature; when the temperature of the furnace tube reaches the deposition temperature, the silicon wafer in the furnace tube is subjected to deposition treatment, temperature promotion treatment and high-temperature oxidation treatment; when the furnace tube is controlled to cool down to the low-temperature oxidation temperature, water vapor with a preset pressure and preset steam temperature is introduced into the furnace tube by bleed air during this process, and it lasts for a preset time; the furnace tube is subjected to a second cooling operation to reduce the temperature in the furnace tube to the standby temperature. This scheme utilizes the difference between water vapor oxidation and conventional dry oxygen to solve the problem of too low initial doping concentration caused by the rapid entry of boron atoms doped into the silicon base into the borosilicate glass body due to high-temperature oxidation during the doping process, that is, the concentration depression phenomenon in the ECV test, thereby solving the problem of high contact resistance between silicon and metal electrodes, so that the P-type doped emitter forms a good ohmic contact with the metal electrode, thereby effectively improving the photoelectric conversion efficiency of silicon cells.

Embodiment 2

FIG2 is a block diagram of a boron diffusion process control device according to an embodiment of the present application;

As shown in FIG2 , the boron diffusion process control device provided in this embodiment is applied to a furnace tube, and includes at least a processor 101 and a memory 102, which are connected via a data bus 103. The memory is used to store computer programs or instructions, and the processor is used to obtain and execute corresponding computer programs or instructions, so that the boron diffusion process control device, which is used to control the furnace tube, implements the boron diffusion process control method provided in the above embodiment.

The boron diffusion treatment control method specifically controls the furnace tube to heat up from the standby temperature to the deposition temperature; when the temperature of the furnace tube reaches the deposition temperature, the silicon wafer in the furnace tube is subjected to deposition treatment, temperature promotion treatment and high-temperature oxidation treatment; when the furnace tube is controlled to cool down to the low-temperature oxidation temperature, water vapor with a preset pressure and preset steam temperature is introduced into the furnace tube by bleed air during this process, and the process lasts for a preset time; the furnace tube is subjected to a second cooling operation to reduce the temperature in the furnace tube to the standby temperature. This solution utilizes the difference between water vapor oxidation and conventional dry oxygen to solve the problem of too low initial doping concentration caused by the rapid entry of boron atoms doped into the silicon base into the borosilicate glass body due to high-temperature oxidation during the doping process, that is, the concentration depression phenomenon in the ECV test, thereby solving the problem of high contact resistance between silicon and metal electrodes, so that the P-type doped emitter forms a good ohmic contact with the metal electrode, thereby effectively improving the photoelectric conversion efficiency of silicon cells.

Embodiment 3

FIG3 is a furnace tube according to an embodiment of the present application. The key point is that the furnace tube is provided with the boron diffusion treatment control device provided in the above embodiment. In order to adapt to the control method of the device, the furnace tube includes a tube body 10 and a main air intake pipe 20 provided at one end of the tube body. The main air intake pipe is connected to a boron source air intake pipe 21, a nitrogen air intake pipe 22, an oxygen air intake pipe 23, and is also connected to one end of a water vapor air intake pipe 24.

The furnace tube also includes a steam generating device 30, which includes a bottle body 31, which is connected to the other end of the water vapor inlet pipe, and is provided with a water injection pipe 32 for injecting deionized water, an air inlet pipe 33 for injecting induced air, a piston 34 and an air outlet 35.

The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

Those skilled in the art will appreciate that the embodiments of the embodiments of the present invention may be provided as methods, devices, or computer program products. Therefore, the embodiments of the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the embodiments of the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

The embodiments of the present invention are described with reference to the flowcharts and/or block diagrams of the methods, terminal devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and/or box in the flowchart and/or block diagram, as well as the combination of the processes and/or boxes in the flowchart and/or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing terminal device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing terminal device generate a device for implementing the functions specified in one process or multiple processes in the flowchart and/or one box or multiple boxes in the block diagram.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing terminal device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction device that implements the functions specified in one or more processes in the flowchart and/or one or more boxes in the block diagram.

These computer program instructions can also be loaded onto a computer or other programmable data processing terminal device so that a series of operating steps are executed on the computer or other programmable terminal device to produce computer-implemented processing, so that the instructions executed on the computer or other programmable terminal device provide steps for implementing the functions specified in one or more processes in the flowchart and/or one or more boxes in the block diagram.

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.

Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

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 (7)

1. The boron diffusion treatment control method is applied to the furnace tube and is characterized by comprising the following steps of:

Controlling the furnace tube to rise from the standby temperature to the deposition temperature;

when the temperature of the furnace tube reaches the deposition temperature, carrying out deposition treatment, heating and pushing treatment and high-temperature oxidation treatment on the silicon wafer in the furnace tube;

After the high-temperature oxidation treatment is performed, performing a first cooling operation on the furnace tube so as to reduce the temperature in the furnace tube to a low-temperature oxidation temperature, and introducing water vapor with preset pressure and preset steam temperature into the furnace tube by utilizing air entraining in the process of performing the first cooling operation on the furnace tube for a preset duration; wherein the high-temperature oxidation temperature is 950-1000 ℃, and the low-temperature oxidation temperature is 950-850 ℃; when the bleed air is nitrogen, the preset pressure is 600-900 mbar, and the preset steam temperature is 40-80 ℃;

and executing a second cooling operation on the furnace tube so as to reduce the temperature in the furnace tube to the standby temperature.

2. The boron diffusion process control method according to claim 1, wherein when the bleed air is nitrogen gas, the flow rate of the bleed air is 3000sccm, and the flow rate of the water vapor is 2000sccm.

3. The boron diffusion process control method of claim 1, wherein the predetermined time period is 10 to 40 minutes.

4. The boron diffusion process control method according to any one of claims 1 to 3, wherein the standby temperature is 790 to 850 ℃ and the deposition temperature is 850 to 900 ℃.

5. The boron diffusion process control method of claim 4, wherein said performing a deposition process, a temperature increase advancing process and a high temperature oxidation process on said silicon wafer in said furnace tube comprises the steps of:

Performing a deposition process on the silicon wafer at the deposition temperature;

After the deposition treatment is finished, controlling the temperature in the furnace tube to rise to 950-1000 ℃, and heating and propelling the silicon wafer in the heating process;

And controlling the temperature in the furnace tube to be 950-1000 ℃, and introducing dry oxygen with the flow of 8L/min-full range during the period to perform high-temperature oxidation treatment on the silicon wafer.

6. A boron diffusion process control device for a furnace tube, comprising at least one processor and a memory, wherein:

The memory is used for storing a computer program or instructions;

The processor is configured to execute the computer program or instructions to cause the boron diffusion process control device to execute the boron diffusion process control method according to any one of claims 1 to 5.

7. A furnace tube provided with the boron diffusion treatment control device as defined in claim 6, wherein the furnace tube at least comprises a tube body and a main air inlet tube arranged at one end of the tube body, and further comprises a boron source air inlet tube, a nitrogen air inlet tube, an oxygen air inlet tube and a water vapor air inlet tube which are respectively communicated with the main air inlet tube;

One end of the steam inlet pipe is communicated with the main inlet pipe, and the other end of the steam inlet pipe is communicated with the steam generating device;

The steam generating device comprises a bottle body for containing deionized water;

The bottle body is also provided with a water injection pipe, an air inlet pipe, a piston and an air outlet hole.