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CN-121977347-A - Low-pressure vertical diffusion furnace and working method thereof

CN121977347ACN 121977347 ACN121977347 ACN 121977347ACN-121977347-A

Abstract

The invention provides a low-pressure vertical diffusion furnace and a working method thereof, and relates to the field of low-pressure vertical diffusion furnaces, wherein the low-pressure vertical diffusion furnace comprises a wafer boat, upright posts, and lifting seats, wherein the lifting seats are arranged on the upright posts in a lifting manner, lifting driving components are arranged on the upright posts, and the lifting driving components are connected with the lifting seats; the rotary seat is rotatably arranged on the lifting seat, the lifting seat is connected with a rotary driving assembly, the wafer boat is arranged on the rotary seat, the furnace door is arranged on the lifting seat, and the furnace door is arranged on the upper part of the rotary seat. The invention can rotate during heating, ensure that the wafer is heated uniformly and improve the quality.

Inventors

  • SONG DEPENG
  • ZHANG ZHENGWEI

Assignees

  • 山东力冠微电子装备有限公司

Dates

Publication Date
20260505
Application Date
20260112

Claims (10)

  1. 1. The utility model provides a vertical diffusion furnace of low pressure, includes furnace body (7), wafer boat (8) and stand (2), its characterized in that still includes: the lifting seat (3), the lifting seat (3) is arranged on the upright post (2) in a lifting manner, a lifting driving assembly (19) is arranged on the upright post (2), and the lifting driving assembly (19) is connected with the lifting seat (3); the rotary seat (9), the rotary seat (9) is rotatably arranged on the lifting seat (3), the lifting seat (3) is connected with a rotary driving assembly (14), and the wafer boat (8) is arranged on the rotary seat (9); The furnace door (6), furnace door (6) set up on elevating seat (3), furnace door (6) set up rotary seat (9) upper portion, furnace door (6) can with furnace body (7) butt.
  2. 2. The low-pressure vertical diffusion furnace according to claim 1, wherein the rotary driving assembly (14) comprises a rotary motor (4), the rotary motor (4) comprises a motor shaft (11), the motor shaft (11) penetrates through the lifting seat (3) and the furnace door (6) and then is connected with the rotary seat (9), a magnetic fluid sealing piece (12) is arranged between the motor shaft (11) and the furnace door (6), the rotary motor (4) is provided with an encoder, and the rotary motor (4) is connected with the lower end of the magnetic fluid sealing piece (12).
  3. 3. The low pressure vertical diffusion furnace according to claim 2, characterized in that a positioning pin (10) is arranged between the boat (8) and the swivel base (9).
  4. 4. A low pressure vertical diffusion furnace according to claim 3, characterized in that the lifting drive assembly (19) comprises a lifting motor (1), the lifting motor (1) is arranged at the top of the upright (2), the lifting motor (1) is connected with a screw (18), the screw (18) is rotatably arranged on the lifting seat (3), a screw is arranged on the screw (18), and the screw is connected with the lifting seat (3).
  5. 5. The low-pressure vertical diffusion furnace according to claim 4, characterized in that the upright (2) is provided with a distance measuring sensor (17), said distance measuring sensor (17) being able to measure the position of the lifting seat (3).
  6. 6. A low-pressure vertical diffusion furnace according to any one of claims 1-5, characterized in that a sealing ring (13) is provided on the sealing surface of the furnace door (6).
  7. 7. The low-pressure vertical diffusion furnace according to claim 6, characterized in that a sealing active compensation assembly is arranged between the furnace door (6) and the lifting seat (3), and when the sealing ring (13) fails, the sealing active compensation assembly can adjust the position of the furnace door (6) before the lifting driving assembly (19).
  8. 8. The low-pressure vertical diffusion furnace according to claim 7, wherein the sealing active compensation assembly comprises a plurality of springs (15), the springs (15) are circumferentially arranged on the end face of the lifting seat (3), two ends of each spring (15) are respectively abutted to the lifting seat (3) and the furnace door (6), a guide rod (20) is arranged on the furnace door (6), the guide rod (20) stretches into a guide hole of the lifting seat (3), the guide rod (20) can move along the guide hole, a limit nut (21) is arranged at the end part of the guide rod (20), and a gap exists between the limit nut (21) and the lower surface of the lifting seat (3).
  9. 9. The low-pressure vertical diffusion furnace according to claim 8, characterized in that the lifting seat (3) is provided with an optical fiber displacement sensor (16), and the optical fiber displacement sensor (16) can detect the distance between the furnace door (6) and the lifting seat (3).
  10. 10. A method of operating a low pressure vertical diffusion furnace according to claim 9, comprising the steps of: S01, placing the wafer on a wafer boat (8), and conveying the wafer into a furnace through a lifting seat (3); S02, continuously moving the lifting seat (3) until the lifting seat moves to a set height; s03, rotating the rotating seat (9) at a set rotating speed; S04, when the sealing acting force of the sealing ring (13) is reduced, the spring (15) automatically stretches to compensate the loss of the sealing compression amount; And S05, when the optical fiber displacement sensor (16) detects that the distance between the furnace door (6) and the lifting seat (3) is reduced, the lifting driving assembly (19) drives the lifting seat (3) to move until the distance between the furnace door (6) and the lifting seat (3) reaches a set threshold value.

Description

Low-pressure vertical diffusion furnace and working method thereof Technical Field The invention relates to the field of low-pressure vertical diffusion furnaces, in particular to a low-pressure vertical diffusion furnace and a working method thereof. Background In the semiconductor manufacturing industry, a Low-pressure diffusion furnace (Low-Pressure Diffusion Furnace) is mainly used for performing high-temperature heat treatment processes under a controlled Low-pressure environment, such as doping diffusion, oxidation, annealing, low-pressure chemical vapor deposition (LPCVD), and the like, and has the core function of realizing uniform diffusion of impurity atoms (such as boron and phosphorus) in a silicon wafer or batch deposition of high-quality films (such as polysilicon, silicon nitride and silicon dioxide) by precisely controlling temperature, atmosphere and pressure. The furnace tube and the external heating component of the vertical low-pressure diffusion furnace adopt coaxial symmetrical multilayer nested structures, the core furnace tube is a high-purity quartz tube, the outer side of the furnace tube is tightly surrounded by a plurality of groups of silicon carbon rods or silicon molybdenum rod heating elements, the heating elements are independently distributed according to partitions, each partition is provided with a special temperature control module and a platinum-rhodium thermocouple, accurate partition temperature adjustment can be realized, a high-density alumina fiber heat preservation layer is filled between the heating element and the furnace tube, the heat preservation layer can effectively reduce heat dissipation and weaken radial temperature gradient of the furnace body, in addition, the outermost layer of the heating component is a metal sealing shell, not only plays a structural supporting role, but also can isolate external environment interference, and the upper end and the lower end of the furnace tube are respectively connected with a gas distribution system and a crystal boat transmission mechanism through high-temperature resistant sealing pieces, so that the tightness of the low-pressure environment in the furnace and the uniform circulation of process gas are ensured. However, by adopting the technical scheme, the phenomenon that the wafer is heated unevenly still exists, manufacturing tolerance exists in the heating elements which are arranged in a surrounding mode, oxidation aging at different rates can occur after long-term high-temperature operation, heating power of each partition is inconsistent, meanwhile, monitoring points of thermocouples are limited, temperature distribution of the whole area in the furnace is difficult to feed back in real time, and hysteresis exists in adjustment of a temperature control system. Disclosure of Invention In order to solve the technical problem of uneven heating of the vertical diffusion furnace in the prior art, the invention provides the low-pressure vertical diffusion furnace and the working method thereof, which can enable a wafer boat to rotate in the diffusion furnace, ensure that wafers are heated uniformly and improve the quality. The invention aims to solve the technical problems, and adopts the technical scheme that the low-pressure vertical diffusion furnace comprises a crystal boat, a stand column, a lifting seat, a rotating seat, a furnace door and a furnace door, wherein the lifting seat is arranged on the stand column in a lifting manner, a lifting driving assembly is arranged on the stand column and connected with the lifting seat, the rotating seat is rotatably arranged on the lifting seat and connected with a rotating driving assembly, the crystal boat is arranged on the rotating seat, the furnace door is arranged on the lifting seat, the furnace door is arranged on the upper part of the rotating seat, and the furnace door can be abutted with the furnace body. According to the invention, the wafer boat is driven to rotate through the rotating seat and the rotary driving assembly, so that wafers are scanned in different temperature areas in the circumferential direction, time-averaged heat exposure is realized, the uniformity of a temperature field is improved, meanwhile, the atmosphere in a furnace can be fully stirred by the rotation of the wafer boat, a boundary layer is disturbed, the reaction gas is promoted to uniformly contact each silicon wafer, each silicon wafer is periodically positioned at different air flow positions in the furnace tube, the temperature and the concentration gradient are averaged, the diffusion uniformity is obviously improved, and local over-doping or under-doping is reduced. Further, the rotary driving assembly comprises a rotary motor, the rotary motor is arranged on the lifting seat, the rotary motor comprises a motor shaft, the motor shaft penetrates through the lifting seat and the furnace door and then is connected with the rotary seat, a magnetic fluid sealing piece is arra