A single-peak high-temperature heating furnace for PN junction diffusion or passivation and its application

Abstract

The present invention provides a single-peak high-temperature heating furnace for PN junction diffusion or passivation and its application. The heating furnace has a temperature control device, and the main body of the heating furnace is a furnace tube, one end of the furnace tube is a silicon wafer inlet, and the other end is a silicon wafer outlet. The silicon wafer inlet and outlet ends of the furnace tube are low-temperature areas, and the middle part is a high-temperature area. The above-mentioned single-peak high-temperature heating furnace for PN junction diffusion or passivation of the present invention can be used for diffusion and passivation of silicon wafers. The diffusion and passivation achieved by the above-mentioned heating furnace improve the consistency of the sintering process of multiple silicon wafers entering and leaving the furnace, and improve the consistency of characteristic parameters.

Description

Technical Field

[0001] The invention relates to a heating furnace and a heating method, in particular to a heating furnace with a single peak high temperature for PN junction diffusion or passivation and a heating method, belonging to the technical field of PN junction preparation. Background Art

[0002] Diffusion and passivation are particularly critical processes in the preparation of semiconductor devices, which determine the uniformity and controllability of the PN junction.

[0003] The existing diffusion process is generally carried out in a diffusion furnace, which is a closed heating chamber with heating wires wrapped around the surface. The existing diffusion furnace heating wires are evenly wound, and the products enter and exit in one direction. The operation method of the diffusion furnace is relatively simple, and the furnace body is simple in workmanship. However, when rapid temperature rise and diffusion are required, batch operations are required, the diffusion consistency between the furnace mouth and the furnace tail is poor, and there are large differences in electrical parameters between the sheets.

[0004] During the glass passivation sintering cooling process, the faster the cooling speed from the glass powder flow temperature point to the softening temperature point, the smaller the diameter of the microcrystal, and the faster the glass stress disappears, which can reduce the deformation and breakage of the silicon wafer and improve the consistency of the product sintering point characteristics. The current glass passivation sintering furnace has a large heat capacity and a slow cooling speed, which is not easy to form glass film. The single point of product entry and exit leads to the situation of first-in-last-out of products, affecting the consistency of product electrical parameters. Summary of the invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a heating method suitable for silicon wafer diffusion and passivation during PN junction preparation, which can achieve rapid entry and exit, improve the consistency of the sintering process of multiple silicon wafers entering and exiting the furnace, and improve the consistency of characteristic parameters.

[0006] In order to achieve the above technical objectives, the present invention first provides a single-peak high-temperature heating furnace for PN junction diffusion or passivation, the heating furnace has a temperature control device, the heating furnace body is a furnace tube, one end of the furnace tube is a silicon wafer inlet, and the other end is a silicon wafer outlet, the silicon wafer inlet and outlet ends of the furnace tube are low-temperature zones, and the middle part is a high-temperature zone.

[0007] In the unimodal high-temperature heating furnace for PN junction diffusion or passivation of the present invention, the temperature of the furnace tube is distributed in a gradient with a high-temperature single peak. Along the length direction of the furnace tube, there is a low-temperature zone first and then a high-temperature zone, and then a low-temperature zone again after the high-temperature zone (its temperature curve has a high-temperature interval or point). When heating a material, the heating furnace with a unimodal high temperature can effectively increase the cooling rate of the material, and can achieve simultaneous heating of multiple materials, improve production efficiency and ensure the consistency of the performance of multiple materials. Combined with the inlet and outlet ends being respectively arranged at both ends of the furnace tube, the material can be heated evenly and the heating conditions can be consistent.

[0008] In a specific embodiment of the present invention, the temperature control device can be a heating wire, and a single-peak high temperature is achieved by non-uniform winding of the heating wire (winding around the outer surface of the furnace tube). The winding density is different, and the winding interval in the middle of the furnace tube is the densest, and the winding interval at both ends is sparse.

[0009] In a specific embodiment of the present invention, three sections of heating wires with different winding intervals are arranged along the length direction of the furnace tube, wherein the winding interval of the first section of the heating wire: the winding interval of the second section of the heating wire: the winding interval of the third section of the heating wire can be 2-3:1-2:2-3, 3-4:1-2:3-4, or 3-4:2-3:3-4 (excluding the case where the winding intervals of the three sections of the heating wire are the same).

[0010] Specifically, the winding interval of the first section of the heating wire is 15mm-20mm, the winding interval of the second section of the heating wire is 10mm-15mm, and the winding interval of the third section of the heating wire is 15mm-20mm; or, the winding interval of the first section of the heating wire is 10mm-15mm, the winding interval of the second section of the heating wire is 5mm-10mm, and the winding interval of the third section of the heating wire is 10mm-15mm; or, the winding interval of the first section of the heating wire is 15mm-20mm, the winding interval of the second section of the heating wire is 5mm-10mm, and the winding interval of the third section of the heating wire is 15mm-20mm.

[0011] In a specific embodiment of the present invention, five sections of heating wires with different winding intervals are arranged along the length direction of the furnace tube, wherein the winding interval of the first section of the heating wire: the winding interval of the second section of the heating wire: the winding interval of the third section of the heating wire: the winding interval of the fourth section of the heating wire: the winding interval of the fifth section of the heating wire is 3-4:2-3:1-2:2-3:3:4 (excluding the case where the winding intervals of the five sections of the heating wire are the same).

[0012] Specifically, the winding interval of the first section of the heating wire is 15mm-20mm, the winding interval of the second section of the heating wire is 10mm-15mm, the winding interval of the third section of the heating wire is 5mm-10mm, the winding interval of the fourth section of the heating wire is 10mm-15mm, and the winding interval of the fifth section of the heating wire is 15mm-20mm.

[0013] In a specific embodiment of the present invention, the temperature control device may be a heating wire, and the single peak high temperature is achieved by winding heating wires of different thicknesses. The cross-sectional diameters of the heating wires are different, the cross-sectional diameter of the heating wire in the middle of the furnace tube is the thickest, and the cross-sectional diameters of the heating wires at both ends are thin.

[0014] In a specific embodiment of the present invention, three sections of heating wires of different thicknesses are included along the length direction of the furnace tube; the ratio of the cross-sectional diameter of the first section of the heating wire: the cross-sectional diameter of the second section of the heating wire: the cross-sectional diameter of the third section of the heating wire is 2-3:1-2:2-3, 3-4:1-2:3-4, or 3-4:2-3:3-4 (excluding the case where the cross-sectional diameters of the three sections of the heating wire are the same).

[0015] In a specific embodiment of the present invention, five sections of heating wires of different thicknesses are arranged along the length direction of the furnace tube, wherein the cross-sectional diameter of the first section of the heating wire: the cross-sectional diameter of the second section of the heating wire: the cross-sectional diameter of the third section of the heating wire: the cross-sectional diameter of the fourth section of the heating wire: the cross-sectional diameter of the fifth section of the heating wire is 3-4:2-3:1-2:2-3:3:4 (excluding the case where the cross-sectional diameters of the five sections of the heating wire are the same).

[0016] In a specific embodiment of the present invention, the cross-sectional diameter of the heating wire may be 5 mm-10 mm.

[0017] In a specific embodiment of the present invention, the total length of the heating area covered by the heating wire is 1 / 3-3 / 4 of the total length of the furnace tube. For example, the total length of the heating area covered by the heating wire is 100cm-150cm, the length of the furnace tube (quartz tube) can be 200-300cm, and the length of the quartz boat can be 40-80cm.

[0018] The single-peak high-temperature heating furnace for PN junction diffusion or passivation of the present invention can process at least 200 silicon wafers at a time.

[0019] The heating furnace of the present invention can be used as a PN junction diffusion furnace for diffusing silicon wafers, wherein the diffusion furnace can be a vertical diffusion furnace or a horizontal diffusion furnace. In addition, the heating furnace of the present invention can also be used as a PN junction passivation furnace for passivating silicon wafers.

[0020] The heating furnace of the present invention can be used for the diffusion or passivation process of silicon wafers in the preparation of PN junctions. When the heating furnace is used for the diffusion or passivation of PN junctions, the steps include:

[0021] Control the temperature of the furnace tube to achieve temperature gradient distribution;

[0022] Feed the silicon wafer into the furnace tube from the silicon wafer inlet, place it in the non-high temperature area, cover it with a quartz cap, and ventilate it;

[0023] The movement speed of the silicon wafer is controlled, and the silicon wafer moves in the furnace tube and moves out from the silicon wafer outlet end of the furnace tube to complete the diffusion or passivation operation.

[0024] In a specific embodiment of the present invention, the ventilation time is 5 min-20 min.

[0025] In a specific embodiment of the present invention, at least 200 silicon wafers are placed in the quartz boat.

[0026] In a specific embodiment of the present invention, the transport speed of the silicon wafer in different temperature ranges is different. For example, the transport speed may be 20 mm / min-200 mm / min.

[0027] The present invention also provides a diffusion method of a PN junction with a single peak high temperature, which is realized by the above-mentioned heating furnace of the present invention. The present invention also provides a preparation method of a PN junction, which adopts the diffusion method of the present invention for diffusion.

[0028] The present invention further provides a passivation method for a PN junction with a single peak high temperature, and the passivation method is realized by the above-mentioned heating furnace of the present invention.

[0029] The present invention also provides a method for preparing a PN junction, which adopts the passivation method of the present invention for passivation. The PN junction diffusion or passivation of the present invention uses a single-peak high-temperature heating furnace, which can process more pieces per furnace, thereby improving production efficiency.

[0030] When the single-peak high-temperature heating furnace for PN junction diffusion or passivation of the present invention is used for the diffusion of PN junction, the temperature of the heating furnace is distributed in a gradient manner, and the quartz boat enters at one end (furnace tail) and exits at the other end (furnace mouth), thereby achieving the product parameter requirements while reducing the discreteness of the product parameters, increasing the number of products produced at a single time, improving the consistency of the sintering process of multiple silicon wafers entering and exiting, and improving production efficiency.

[0031] The single-peak high-temperature heating furnace for PN junction diffusion or passivation of the present invention can effectively increase the cooling rate of silicon wafers and reduce deformation and breakage of silicon wafers when used for passivation of PN junctions. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic structural diagram of a heating furnace for PN junction diffusion according to an embodiment of the present invention.

[0033] Figure 2 Schematic diagram of the distribution of heating wires of a heating furnace for PN junction diffusion according to an embodiment of the present invention.

[0034] Description of main figures:

[0035] 1. Quartz cap; 2. Heating wire; 3. Furnace tube; 4. Quartz boat. DETAILED DESCRIPTION

[0036] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be construed as limiting the applicable scope of the present invention.

[0037] Example 1

[0038] This embodiment provides a single peak high temperature heating furnace, which has the following characteristics: Figure 1 The structure shown in the figure, the main body of the heating furnace is a furnace tube 3, the quartz cap 1 is connected to the furnace tube 3 (quartz tube) by frosting, a quartz boat 4 is arranged inside the furnace tube 3, and 5 sections of heating wire 2 are arranged along the length direction of the furnace tube 3, wherein the first section of heating wire (such as Figure 2 The winding interval of the A1 section shown in the figure is 15mm-20mm, and the second heating wire (such as Figure 2 The winding interval of the B1 section shown in the figure is 10mm-15mm, and the third heating wire (such as Figure 2 The winding interval of the fourth heating wire (such as Figure 2 The winding interval of the fifth heating wire (such as B2) is 10mm-15mm. Figure 2 The winding interval of the A2 section shown is 15mm-20mm. The diameter of the heating wire is 5mm-10mm.

[0039] The total length of the A1 section, B1 section, C section, B2 section and A2 section is 100-150 cm, the length of the furnace tube 3 is 200-300 cm, and the length of the quartz boat 4 is 40-80 cm.

[0040] This embodiment also provides a method of Figure 1 The diffusion method of PN junction realized by a single peak high temperature heating furnace includes:

[0041] The temperature of the furnace tube of the diffusion furnace is controlled to achieve a temperature gradient distribution; the temperature of the first section is 400℃-650℃, the temperature of the second section is 550℃-800℃; the temperature of the third section is 700℃-1000℃; the temperature of the fourth section is 550℃-800℃, and the temperature of the fifth section is 400℃-650℃;

[0042] The quartz boat contains at least 200 silicon wafers. The quartz boat is sent into the furnace from the tail of the furnace tube, placed in the non-high temperature area, covered with a quartz cap, and ventilated for 5-20 minutes.

[0043] Control the moving speed of the quartz boat, move the quartz boat to the furnace mouth of the furnace tube, and complete the diffusion operation.

[0044] Example 2

[0045] This embodiment provides a Figure 1 The passivation method of PN junction realized by a single peak high temperature heating furnace includes:

[0046] The temperature of the furnace tube of the heating furnace is controlled to achieve a temperature gradient distribution; the temperature of the first section is 400℃-650℃, the temperature of the second section is 550℃-800℃; the temperature of the third section is 700℃-1000℃; the temperature of the fourth section is 550℃-800℃, and the temperature of the fifth section is 400℃-650℃;

[0047] The quartz boat contains at least 200 silicon wafers. The quartz boat is sent into the furnace from the tail of the furnace tube, placed in the non-high temperature area, covered with a quartz cap, and ventilated for 5-20 minutes.

[0048] Control the moving speed of the quartz boat, move the quartz boat to the furnace mouth of the furnace tube, and complete the passivation operation.

Claims

1. A single-peak high-temperature heating furnace for PN junction diffusion or passivation, the heating furnace having a temperature control device, the heating furnace body being a furnace tube, one end of the furnace tube being a silicon wafer inlet, and the other end being a silicon wafer outlet, the silicon wafer inlet and outlet ends of the furnace tube being low-temperature zones, and the middle being a high-temperature zone; The temperature control device is a heating wire, and 5 sections of heating wires with different winding intervals are arranged along the length direction of the furnace tube, the winding interval of the first section of the heating wire: the winding interval of the second section of the heating wire: the winding interval of the third section of the heating wire: the winding interval of the fourth section of the heating wire: the winding interval of the fifth section of the heating wire is 3-4:2-3:1-2:2-3:3:4; the winding interval of the first section of the heating wire is 15mm-20mm, the winding interval of the second section of the heating wire is 10mm-15mm, the winding interval of the third section of the heating wire is 5mm-10mm, the winding interval of the fourth section of the heating wire is 10mm-15mm, and the winding interval of the fifth section of the heating wire is 15mm-20mm, and the total length of the heating area covered by the heating wire is 1 / 3-3 / 4 of the total length of the furnace tube; The cross-sectional diameter of the first heating wire section: the cross-sectional diameter of the second heating wire section: the cross-sectional diameter of the third heating wire section: the cross-sectional diameter of the fourth heating wire section: the cross-sectional diameter of the fifth heating wire section is 3-4:2-3:1-2:2-3:3:4, excluding the case where the cross-sectional diameters of the 5 heating wire sections are the same, and the cross-sectional diameter of the heating wire is 5mm-10mm.

2. The heating furnace according to claim 1, in, The heating furnace can process at least 200 silicon wafers at a time.

3. Use of the single-peak high-temperature heating furnace for PN junction diffusion or passivation as described in claim 1 or 2, wherein the heating furnace is used for the diffusion or passivation process of silicon wafers in the preparation of PN junctions.

4. The use according to claim 3, in, This heating furnace is used for diffusion or passivation of silicon wafers in PN junction preparation, including: Control the temperature of the furnace tube to achieve a temperature gradient distribution; Feed the silicon wafer into the furnace tube from the silicon wafer inlet, place it in the non-high temperature area, cover it with a quartz cap, and ventilate it; The movement speed of the silicon wafer is controlled, and the silicon wafer moves in the furnace tube and is removed from the silicon wafer outlet to complete the diffusion or passivation process.

5. The use according to claim 4, in, The ventilation time is 5min-20min.

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