Crystal growth furnace oxidation device for growth of ultra-low-resistance red phosphorus crystal bar

Abstract

The utility model discloses a crystal growth furnace oxidation device for ultralow-resistance red phosphorus crystal bar growth. The crystal growth furnace oxidation device comprises an upper CDA conveying system connected with an auxiliary furnace chamber and a lower CDA conveying system connected with a vacuum pipeline, the upper CDA conveying system comprises an upper CDA conveying pipeline, an upper CDA flow meter and an upper CDA control valve, wherein the upper CDA flow meter and the upper CDA control valve are arranged on the upper CDA conveying pipeline. The lower CDA conveying system comprises a lower CDA conveying pipeline, a lower CDA flow meter and a lower CDA control valve, wherein the lower CDA flow meter and the lower CDA control valve are arranged on the lower CDA conveying pipeline. And the auxiliary furnace chamber and the main furnace chamber are respectively connected with an argon conveying system. According to the method, through the synergistic effect of the dry compressed air and the argon, silicified phosphorus oxides of the inner furnace wall, the thermal field and the vacuum pipeline of the crystal growth furnace are fully oxidized and removed, and explosion in furnace opening for taking crystal bars, furnace wall cleaning, thermal field cleaning and vacuum pipe wall cleaning is effectively avoided.

Description

An oxidation apparatus for growing ultra-low resistivity red phosphorus crystal rods in a crystal growth furnace. Technical Field

[0001] This utility model belongs to the field of semiconductor manufacturing technology, specifically relating to a crystal growth furnace oxidation device for growing ultra-low resistivity red phosphorus crystal rods. Background Technology

[0002] The general method for growing ultra-low resistivity red phosphorus crystal rods includes: when the temperature inside the crystal growth furnace reaches about 1300℃, red phosphorus is doped into the polycrystalline silicon melt through a vapor phase doping method, and then the crystal rod growth is completed through steps such as temperature testing, crystal pulling, shoulder formation, shoulder rotation, equal diameter formation, tailing, furnace shutdown, oxidation, furnace opening, and crystal rod removal.

[0003] After the ultra-low resistivity red phosphorus semiconductor ingot growth is completed and the furnace is shut down, the ingot remains in the auxiliary chamber of the crystal growth furnace, where the furnace temperature is maintained at approximately 500℃ to 1000℃. Because the red phosphorus required for doping the ultra-low resistivity red phosphorus semiconductor ingot has a very low ignition point, some of the dopant red phosphorus easily volatilizes and deposits along with other oxides on the furnace walls, hot zone, and vacuum pipes during the doping and pulling process. This volatilization can easily cause combustion during furnace startup. Therefore, to avoid these problems after furnace shutdown, oxidizing gas needs to be introduced into the furnace to fully oxidize the deposited phosphorus-containing volatiles, allowing them to volatilize and be removed.

[0004] However, if oxidation is insufficient and the deposited phosphorus-containing volatiles are not completely removed, directly exposing the furnace to atmospheric pressure may cause an explosion when the furnace is opened, damaging the crystal, the thermal field and equipment, and even injuring the operators. Therefore, fully oxidizing the furnace wall, thermal field and vacuum pipeline is a very critical procedure, which is related to the life of the thermal field, the thermal history of crystal cooling, and the formation of crystal rod defects such as oxygen precipitation. Summary of the Invention

[0005] The purpose of this invention is to provide an oxidation device for a crystal growth furnace for the growth of ultra-low resistivity red phosphorus crystal rods, so as to overcome the shortcomings of the existing technology, and to fully oxidize and remove the phosphorus-containing volatiles deposited in the crystal growth furnace, thereby effectively avoiding explosions caused by phosphorus-containing deposits.

[0006] The objective of this utility model is achieved through the following technical solution:

[0007] An oxidation apparatus for growing ultra-low resistivity red phosphorus crystal rods in a crystal growth furnace, the crystal growth furnace comprising a main furnace chamber, a furnace cover and an auxiliary furnace chamber, the main furnace chamber being equipped with a vacuum system for adjusting the pressure of the main furnace chamber, the vacuum system comprising a vacuum pipe communicating with the main furnace chamber, and the oxidation apparatus for growing crystal rods comprising an upper CDA conveying system connected to the auxiliary furnace chamber and a lower CDA conveying system connected to the vacuum pipe;

[0008] The upper CDA conveying system includes an upper CDA conveying pipeline, an upper CDA flow meter installed on the upper CDA conveying pipeline, and an upper CDA control valve;

[0009] The lower CDA conveying system includes a lower CDA conveying pipeline, a lower CDA flow meter installed on the lower CDA conveying pipeline, and a lower CDA control valve;

[0010] The auxiliary furnace chamber and the main furnace chamber are each connected to an argon gas delivery system.

[0011] Preferably, the crystal growth furnace oxidation apparatus further includes a CDA source, and both the upper CDA conveying pipe and the lower CDA conveying pipe are connected to the CDA source.

[0012] Preferably, a filter is provided between the CDA source and the upper CDA delivery pipe and the lower CDA delivery pipe.

[0013] Preferably, the upper CDA control valve and the lower CDA control valve are pneumatic valves.

[0014] Preferably, the upper CDA flow meter and the lower CDA flow meter are float flow meters.

[0015] Preferably, the argon gas delivery system includes a rapid argon gas delivery system connected to the top of the auxiliary furnace chamber, an upper argon gas delivery system connected to the top of the auxiliary furnace chamber, and a lower argon gas delivery system connected to the furnace cover on the upper part of the main furnace chamber.

[0016] Preferably, the argon rapid delivery system includes an argon rapid delivery pipeline and an argon rapid charging valve located on the argon rapid delivery pipeline;

[0017] The upper argon gas delivery system includes an upper argon gas delivery pipeline and an upper argon gas control valve and an upper argon gas flow meter located on the upper argon gas delivery pipeline;

[0018] The lower argon gas delivery system includes a lower argon gas delivery pipeline and a lower argon gas control valve and a lower argon gas flow meter located on the lower argon gas delivery pipeline.

[0019] Preferably, the vacuum system further includes a main pump, and a main connecting pipe is provided between the main pump and the vacuum pipeline; the main connecting pipe is provided with a furnace pressure proportional control valve and a main pump control valve.

[0020] Preferably, the vacuum system further includes an auxiliary pump, and an auxiliary connecting pipe is provided between the auxiliary pump and the vacuum pipe, and an auxiliary pump control valve is provided on the auxiliary connecting pipe;

[0021] An venting pipe is provided between the auxiliary pump and the auxiliary furnace chamber, and an auxiliary chamber venting valve is provided on the venting pipe.

[0022] Preferably, the crystal growth furnace oxidation apparatus further includes a control system and a human-machine interface;

[0023] The control system is electrically connected to the vacuum system, as well as each valve and each flow meter, and is used to control the oxidation operation.

[0024] The human-computer interaction interface is electrically connected to the control system and is used for human-computer interaction.

[0025] This application utilizes the synergistic effect of dry compressed air and argon to fully oxidize and remove silicide and phosphorus oxides from the furnace walls, hot zone, and vacuum pipes inside the crystal growth furnace. This effectively avoids explosions during furnace opening, crystal rod removal, furnace wall cleaning, hot zone cleaning, and vacuum pipe wall cleaning, indirectly protecting products, equipment, hot zone lifespan, and personnel safety. It also effectively inhibits the formation of internal crystal defects. Attached Figure Description

[0026] Figure 1 is a schematic diagram of the structure of the crystal growth furnace oxidation device for growing ultra-low resistivity red phosphorus crystal rods provided in this application;

[0027] Explanation of reference numerals in the attached figures:

[0028] 1-Furnace pressure proportional control valve; 2-Main pump control valve; 3-Vacuum pipeline; 4-Heating electrode; 5-Base; 6-Main furnace chamber; 7-Furnace cover; 8-Auxiliary furnace chamber; 9-Seed crystal lifting mechanism; 10-Argon rapid charging valve; 11-Upper CDA flow meter; 12-Upper CDA control valve; 13-Upper argon flow meter; 14-Upper argon control valve; 15-Lower argon flow meter; 16-Lower argon control valve; 17-Lower CDA control valve; 18-Lower CDA flow meter; 19-Filter; 20-Auxiliary chamber vent valve; 21-Auxiliary pump control valve; 22-Main pump; 23-Auxiliary pump; 24-Upper CDA delivery pipeline; 25-Lower CDA delivery pipeline. Detailed Implementation

[0029] The crystal growth furnace oxidation apparatus for growing ultra-low resistivity red phosphorus crystal rods provided in this application is shown in Figure 1. The crystal growth furnace includes a base 5, a main furnace chamber 6, a furnace cover 7, an auxiliary furnace chamber 8, and a seed crystal lifting mechanism 9. The furnace cover 7 is located on top of the main furnace chamber 6. The top of the furnace cover 7 is connected to the bottom of the auxiliary furnace chamber 8 via an isolation valve. The base 5 supports the main furnace chamber, auxiliary furnace chamber, and other components. A heating electrode 4 is provided on the main furnace chamber 6 to heat the main furnace chamber 6, providing a heat source for crystal rod growth. The seed crystal lifting mechanism 9 is used to rotate and lift the seed crystal. A vacuum system is provided on the main furnace chamber 6 to adjust the pressure within the main furnace chamber. The vacuum system includes a vacuum pipe 3 connected to the main furnace chamber 6, through which gas can be extracted from the main furnace chamber. The base 5, main furnace chamber 6, furnace cover 7, auxiliary furnace chamber 8, seed crystal lifting mechanism 9, heating electrode 4, and vacuum system can all be constructed using conventional technology.

[0030] The crystal growth furnace oxidation device includes an upper CDA (dry compressed air) delivery system connected to the auxiliary furnace chamber 8 and a lower CDA delivery system connected to the vacuum pipeline 3. These systems can respectively deliver dry compressed air to the auxiliary furnace chamber 8 and the vacuum pipeline 3. The dry compressed air introduced into the auxiliary furnace chamber 8 can flow downwards to the main furnace chamber, while the gas introduced into the vacuum pipeline 3 can flow within the vacuum pipeline, fully oxidizing the inner wall of the vacuum pipeline. This ensures the complete oxidation of phosphorus-containing volatiles deposited in the auxiliary furnace chamber 8, the main furnace chamber 6, and the vacuum pipeline 3. A portion of the oxidized phosphorus-containing volatiles is extracted by the vacuum system, and a portion is burned during the oxidation stage. The combustion gases are also extracted by the vacuum system, effectively eliminating the phosphorus-containing volatiles deposited in the auxiliary furnace chamber, the main furnace chamber, and the vacuum pipeline.

[0031] Specifically, the upper CDA conveying system includes an upper CDA conveying pipe 24, an upper CDA flow meter 11 installed on the upper CDA conveying pipe 24, and an upper CDA control valve 12; the lower CDA conveying system includes a lower CDA conveying pipe 25, a lower CDA flow meter 18 installed on the lower CDA conveying pipe 25, and a lower CDA control valve 17; by setting the flow meter and control valve, the input air flow can be easily monitored and controlled. Preferably, the upper CDA control valve 12 and the lower CDA control valve 17 are pneumatic valves, and the upper CDA flow meter 11 and the lower CDA flow meter 18 are float flow meters.

[0032] Preferably, the crystal growth furnace oxidation apparatus further includes a CDA source, with both the upper CDA delivery pipe 24 and the lower CDA delivery pipe 25 connected to the CDA source. The CDA source is used to provide dry compressed air. More preferably, a precision filter 19 is provided between the CDA source and the upper CDA delivery pipe 24 and the lower CDA delivery pipe 25. The dry compressed air is oil-free and water-free dry filtered air obtained by filtering gas compressed by an air compressor through multiple stages of filters. Before entering the crystal growth furnace, it is further filtered by the precision filter 19 to prevent contamination of the crystal growth furnace.

[0033] The main furnace chamber 6 and the auxiliary furnace chamber 8 are respectively connected to an argon gas delivery system, which is used to fill the main furnace chamber 6 and the auxiliary furnace chamber 8 with argon gas to control the furnace pressure for oxidation and phosphorus removal, and at the same time protect the crystal growth furnace and prevent contamination of the crystal growth furnace.

[0034] Preferably, the argon gas delivery system includes a rapid argon gas delivery system connected to the top of the auxiliary furnace chamber 8, an upper argon gas delivery system connected to the top of the auxiliary furnace chamber 8, and a lower argon gas delivery system connected to the furnace cover 7 on the upper part of the main furnace chamber 6. The rapid argon gas delivery system can directly and quickly fill the auxiliary furnace chamber 8 with argon gas, which can then flow rapidly into the main furnace chamber, quickly adjusting the furnace pressure. The upper and lower argon gas delivery systems can directly input a certain amount of argon gas into the auxiliary furnace chamber 8 and the main furnace chamber 6 (through the furnace cover 7), respectively, for precise adjustment of the furnace pressure. The argon gas used is high-purity argon gas, with a purity of 99.9999999%.

[0035] More preferably, the rapid argon delivery system includes a rapid argon delivery pipeline and a rapid argon charging valve 10 located on the rapid argon delivery pipeline; the upper argon delivery system includes an upper argon delivery pipeline and an upper argon control valve 14 and an upper argon flow meter 13 located on the upper argon delivery pipeline; the lower argon delivery system includes a lower argon delivery pipeline and a lower argon control valve 16 and a lower argon flow meter 15 located on the lower argon delivery pipeline. Since the rapid argon delivery pipeline is used to quickly adjust the furnace pressure, precise monitoring and adjustment of the flow rate is not required, and a flow meter is not necessary; only the rapid argon charging valve 10 is needed. The control valves and flow meters installed on the upper and lower argon delivery systems can precisely control the argon delivery volume to accurately adjust the furnace pressure.

[0036] More preferably, the upper argon control valve 14 and the lower argon control valve 16 are also pneumatic valves. The upper argon flow meter 13 and the lower argon flow meter 15 are mass flow meters.

[0037] Preferably, the vacuum system further includes a main pump 22, and a main connecting pipe is provided between the main pump 22 and the vacuum pipe 3; a furnace pressure proportional control valve 1 and a main pump control valve 2 are provided on the main connecting pipe. The main pump 22 can extract gas from the main furnace chamber 6 through the vacuum pipe 3 to adjust the furnace pressure. The furnace pressure proportional control valve 1 can continuously adjust the valve opening ratio to precisely regulate the furnace pressure. The main pump control valve 2 can serve as an isolating switch between the main pump 22 and the main furnace chamber 6.

[0038] Preferably, the vacuum system further includes an auxiliary pump 23, and an auxiliary connecting pipe is provided between the auxiliary pump 23 and the vacuum pipe 3. An auxiliary pump control valve 21 is provided on the auxiliary connecting pipe. The auxiliary pump 23 can assist the main pump 22 in extracting gas from the main furnace chamber 6. The auxiliary pump control valve 21 can control the opening and closing of the auxiliary connecting pipe.

[0039] An venting pipe is provided between the auxiliary pump 23 and the auxiliary furnace chamber 8, and an auxiliary chamber venting valve 20 is provided on the venting pipe. The auxiliary pump 23 can also extract gas from the auxiliary furnace chamber 8 and adjust the pressure of the auxiliary furnace chamber. The venting pipe can be opened or closed by the auxiliary chamber venting valve 20.

[0040] Preferably, the crystal growth furnace oxidation apparatus provided in this application further includes a control system and a human-machine interface; wherein, the control system is electrically connected to the vacuum system, each valve and each flow meter, and can automatically control the oxidation operation; the human-machine interface is electrically connected to the control system and is used for human-machine interaction.

[0041] The specific workflow of the crystal growth furnace oxidation apparatus provided in this application is as follows:

[0042] After the crystal growth furnace is shut down, the crystal travels to the upper limit of the stretching chamber in the auxiliary furnace. After checking the heat leakage rate and confirming that the crystal growth furnace is well-sealed and leak-free, the oxidation is carried out according to the following steps.

[0043] 1. Keep the main pump 22 running continuously, open the main pump control valve 2, and adjust the opening ratio of the furnace pressure proportional control valve 1 to 0% on the human-machine interface;

[0044] 2. Open the argon rapid charging valve 10 to charge argon gas, and quickly adjust the furnace pressure to 280-420 torr (quickly adjusting the furnace pressure to 420 torr can prevent external gas from flowing back into the furnace cavity due to operational errors, thus preventing contamination of the thermal field), and then close the argon rapid charging valve 10.

[0045] 3. After the furnace pressure stabilizes, adjust the opening ratio of the furnace pressure proportional control valve 1 to 5% to 50% to reduce the furnace pressure to about 200 torr and stabilize it.

[0046] 4. Set the flow rate of the upper argon flow meter 13 to 60L / MIN, open the upper argon control valve 14, and adjust the furnace pressure proportional control valve 1 to stabilize the furnace pressure in the range of 45~110 torr;

[0047] 5. Set the flow rate of the upper CDA flow meter 11 to 15L / MIN, open the upper CDA pneumatic valve 12, and the CDA enters the auxiliary furnace chamber 8. At the same time, set the flow rate of the lower CDA flow meter 18 to 15L / MIN, open the lower CDA control valve 17, and the CDA enters the vacuum pipeline 3. Adjust the furnace pressure proportional control valve 1 to keep the furnace pressure within 45~110 torr for the first stage of oxidation and phosphorus removal.

[0048] At this point, the ratio of CDA to argon is 1:2, meaning argon flow rate is 60 L / min, upper CDA flow rate is 15 L / min, and lower CDA flow rate is 15 L / min. Argon and CDA enter the furnace together at this stage.

[0049] 6.2 hours later, set the upper argon flow meter 13 to 0 L / MIN and close the upper argon control valve 14. Charge CDA through the upper CDA delivery pipe 24, adjusting the flow rate of the upper CDA flow meter 11 to 45 L / MIN. Charge CDA through the lower CDA delivery pipe 25, adjusting the flow rate of the lower CDA flow meter 18 to 45 L / MIN, thus controlling the furnace pressure between 45 and 110 torr. At this point, the furnace is completely filled with 90 L / MIN of CDA for oxidation and phosphorus removal.

[0050] 7.2 hours later, close the main pump control valve 2, close the furnace pressure proportional control valve 1, and close the main pump 22. Keep the auxiliary furnace chamber 8 door handle open, use CDA to adjust the furnace pressure to atmospheric pressure, then set the upper CDA flow meter 11 and lower CDA flow meter 18 to 0 L / MIN, and close the upper CDA control valve 12 and lower CDA control valve 17. Gently open the auxiliary furnace chamber 8 door, and perform static oxidation at atmospheric pressure for 1-3 hours, depending on the running time and doping amount during the crystal growth process. The purpose is to allow the silicon oxide in the furnace to self-ignite and cool down, preventing excessive movement from igniting dust storms due to friction. After static oxidation, start removing the crystal rods. The oxidation process is complete, and continue with subsequent operations.

[0051] The crystal growth furnace for growing red phosphorus-doped ingots was operated for one year using this device and method, and no dust storms occurred during ingot removal, handling of the hot zone, or cleaning of the pipelines.

[0052] Therefore, this application utilizes the synergistic effect of dry compressed air and argon to fully oxidize and remove silicide and phosphorus oxides from the furnace walls, hot zone, and vacuum pipes inside the crystal growth furnace. This effectively avoids explosions during furnace opening, crystal rod removal, furnace wall cleaning, hot zone cleaning, and vacuum pipe wall cleaning, indirectly protecting products, equipment, hot zone lifespan, and personnel safety. It also effectively inhibits the formation of internal crystal defects.

[0053] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention. Clearly, those skilled in the art can make various alterations and modifications to the present invention without departing from its spirit and scope. Thus, if these modifications and modifications of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention also intends to include these modifications and modifications.

Claims

1. An oxidation apparatus for growing ultra-low resistivity red phosphorus crystal rods in a crystal growth furnace, the crystal growth furnace comprising a main furnace chamber, a furnace cover, and an auxiliary furnace chamber, wherein a vacuum system is provided on the main furnace chamber for adjusting the pressure of the main furnace chamber, the vacuum system comprising a vacuum pipe communicating with the main furnace chamber, characterized in that, The crystal growth furnace oxidation apparatus includes an upper CDA conveying system connected to the auxiliary furnace chamber and a lower CDA conveying system connected to the vacuum pipeline; the upper CDA conveying system includes an upper CDA conveying pipeline, an upper CDA flow meter and an upper CDA control valve installed on the upper CDA conveying pipeline; the lower CDA conveying system includes a lower CDA conveying pipeline, a lower CDA flow meter and a lower CDA control valve installed on the lower CDA conveying pipeline; the auxiliary furnace chamber and the main furnace chamber are respectively connected to an argon gas conveying system.

2. The crystal growth furnace oxidation apparatus for growing ultra-low resistivity red phosphorus crystal rods as described in claim 1, characterized in that, The crystal growth furnace oxidation apparatus also includes a CDA source, and both the upper CDA conveying pipe and the lower CDA conveying pipe are connected to the CDA source.

3. The crystal growth furnace oxidation apparatus for growing ultra-low resistivity red phosphorus crystal rods as described in claim 2, characterized in that, A filter is provided between the CDA source and the upper CDA delivery pipe and the lower CDA delivery pipe.

4. The crystal growth furnace oxidation apparatus for growing ultra-low resistivity red phosphorus crystal rods as described in claim 1, characterized in that, The upper CDA control valve and the lower CDA control valve are pneumatic valves.

5. The crystal growth furnace oxidation apparatus for growing ultra-low resistivity red phosphorus crystal rods as described in claim 1, characterized in that, The upper CDA flow meter and the lower CDA flow meter are float flow meters.

6. The crystal growth furnace oxidation apparatus for growing ultra-low resistivity red phosphorus crystal rods as described in claim 1, characterized in that, The argon gas delivery system includes a rapid argon gas delivery system connected to the top of the auxiliary furnace chamber, an upper argon gas delivery system connected to the top of the auxiliary furnace chamber, and a lower argon gas delivery system connected to the furnace cover on the upper part of the main furnace chamber.

7. The crystal growth furnace oxidation apparatus for growing ultra-low resistivity red phosphorus crystal rods as described in claim 6, characterized in that, The rapid argon delivery system includes a rapid argon delivery pipeline and a rapid argon filling valve located on the rapid argon delivery pipeline; the upper argon delivery system includes an upper argon delivery pipeline and an upper argon control valve and an upper argon flow meter located on the upper argon delivery pipeline; the lower argon delivery system includes a lower argon delivery pipeline and a lower argon control valve and a lower argon flow meter located on the lower argon delivery pipeline.

8. The crystal growth furnace oxidation apparatus for growing ultra-low resistivity red phosphorus crystal rods as described in claim 1, characterized in that, The vacuum system also includes a main pump, and a main connecting pipe is provided between the main pump and the vacuum pipeline; the main connecting pipe is equipped with a furnace pressure proportional control valve and a main pump control valve.

9. The crystal growth furnace oxidation apparatus for growing ultra-low resistivity red phosphorus crystal rods as described in claim 1, characterized in that, The vacuum system also includes an auxiliary pump, and an auxiliary connecting pipe is provided between the auxiliary pump and the vacuum pipe. An auxiliary pump control valve is provided on the auxiliary connecting pipe. An venting pipe is provided between the auxiliary pump and the auxiliary furnace chamber, and an auxiliary chamber venting valve is provided on the venting pipe.

10. The crystal growth furnace oxidation apparatus for growing ultra-low resistivity red phosphorus crystal rods as described in claim 1, characterized in that, It also includes a control system and a human-machine interface; the control system is electrically connected to the vacuum system and each valve and flow meter, and is used to control the oxidation operation; the human-machine interface is electrically connected to the control system and is used for human-machine interaction.

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