Search

CN-121976303-A - Crystal rotation method in semiconductor preparation process

CN121976303ACN 121976303 ACN121976303 ACN 121976303ACN-121976303-A

Abstract

The invention belongs to the technical field of semiconductor preparation, and particularly relates to a crystal rotation method in the semiconductor preparation process. After the crystal growth base is arranged in the central hole and rotates synchronously with the motor output shaft, the cavity is sealed by a corrugated pipe. And starting the motor to drive the crystal to rotate, and monitoring the growth through the central hole. The method ensures that the rotating structure has large visual field monitoring capability in a limited space, realizes stable rotation under high bearing by the synergistic effect of the bearing and the fixing piece, accurately controls the radial deviation of rotation within +/-0.02 mm, and effectively ensures the uniformity and quality of crystal growth.

Inventors

  • SONG DEPENG
  • CHEN JIANJUN

Assignees

  • 山东力冠微电子装备有限公司

Dates

Publication Date
20260505
Application Date
20251231

Claims (10)

  1. 1. A method of crystal rotation in a semiconductor manufacturing process, the method comprising: S101, configuring a rotating motor, and enabling an output shaft of the rotating motor to be in transmission connection with a crystal rotating carrier so as to drive crystals to be grown to execute rotating action; S102, configuring a guide bearing, sleeving the guide bearing outside an output shaft of a rotating motor, and supporting and guiding the radial movement of the output shaft in a direction; s103, positioning and fixing operation is carried out by adopting a fixing piece, and a guide bearing is connected with the chamber wall so as to stabilize the relative position of the rotating motor and the guide bearing; S104, planning a central hole in the axial center areas of the rotating motor and the guide bearing, so that the hole penetrates through the main areas of the rotating motor and the guide bearing, and the diameter of the hole is larger than 20% of the maximum outer diameter of the crystal to be grown; S105, integrating the rotating motor, the guide bearing and the fixing piece into a crystal rotating device main body, and enabling the main body to form fixed connection with the chamber wall through the fixing piece; S106, arranging a crystal growth base in a central hole of the crystal rotating device main body, so that the base and an output shaft of a rotating motor keep a synchronous rotating state to bear crystals to be grown; S107, performing sealing and isolating operation on the chamber, wrapping the crystal rotating device main body by adopting a corrugated pipe, and enabling the corrugated pipe to form sealing connection with the chamber wall so as to maintain the target environment atmosphere with the vacuum degree in the chamber less than or equal to 1 multiplied by 10 -5 Pa; S108, starting a rotating motor to operate so as to drive a crystal growth base to rotate, monitoring the crystal growth process through a visual field area of the central hole, and controlling the rotation radial deviation of a crystal rotating device main body within +/-0.02 mm based on the radial support of a guide bearing and the positioning action of a fixing piece so as to keep the operation stability.
  2. 2. The method for crystal rotation in a semiconductor manufacturing process according to claim 1, further comprising the step of, after S108: after the crystal growth program is finished, a linear decreasing rotating speed instruction is sent to the rotating motor, so that the rotating speed of the rotating motor for driving the crystal growth base is uniformly reduced to 1 revolution/minute from the process rotating speed within 300 seconds, and after the low-speed rotation is maintained for 60 seconds, the power supply is switched off to stop freely; Through the central hole, a quartz rod arranged on the three-dimensional micro-motion stage is used, and the front end of the quartz rod is slowly contacted with the side surface of the crystal with stopped rotation; Starting the micro-motion stage to enable the quartz rod to axially and slowly translate for 20 mm along the side surface of the crystal, and applying a stable slight lateral constraint force to the crystal in the process; The method comprises the steps of restarting a rotating motor, driving a crystal growth base to rotate for one circle at a speed of 1 revolution/minute, collecting contour distance data of one circle of the side face of the crystal at a sampling frequency of 10Hz by using a laser range finder which aims at the side face of the crystal through a central hole, and comparing and analyzing the contour distance data with initial contour data before the crystal growth.
  3. 3. The method for crystal rotation in a semiconductor manufacturing process according to claim 1, further comprising the step of, after S108: passing a vacuum chuck clamp controlled by an external mechanical arm through the central hole to enable the chuck to contact and be adsorbed on the upper end face of the crystal; Starting a micro electromagnet arranged in a crystal growth base to cut off power, so that the locking force of the micro electromagnet to the bottom of the crystal is released, and the crystal is lifted and moved out of the central hole along the axial direction by a mechanical arm; A hollow gas spray pipe passes through the central hole and is aligned with the surface of the bare crystal growth base, high-purity argon with the pressure of 0.3MPa is introduced into the spray pipe to sweep the surface of the base for 60 seconds, the spray pipe is replaced by a resistance heater, and the spray pipe is inserted into the central hole and heated to ensure that the temperature of the base rises to 350 ℃ within 120 seconds and is maintained for 180 seconds; Under the condition of no crystal load, the rotating motor is started again to drive the crystal growth base to rotate at the speed of 5 revolutions per minute, an industrial endoscope which is fixed outside the cavity and aims at the edge of the base through the observation window is used for recording video images when the base rotates, the video images are compared with reference video recorded under the standard condition frame by frame, and whether the repeatability deviation of the rotating track of the base is within the allowable range is judged through image recognition software.
  4. 4. The method for crystal rotation in a semiconductor manufacturing process according to claim 1, wherein S102 specifically comprises the steps of: selecting a guide bearing with the inner diameter equal to the outer diameter of an output shaft of the rotating motor and the outer diameter adapted to the radial space in the cavity; processing an annular positioning groove on an output shaft of a rotating motor, wherein the groove depth and the width are matched with the size of a stop retainer ring of an inner ring of a guide bearing, or arranging a shaft shoulder at the end part of the output shaft to serve as an axial limiting reference; The guide bearing is pushed in along the axial direction of the output shaft, so that the bearing inner ring is in interference fit with the output shaft until the end face of the bearing inner ring abuts against the retainer ring or the shaft shoulder at the positioning groove, and the bearing outer ring is ensured to be perpendicular to the axis of the output shaft.
  5. 5. The crystal rotation method in the semiconductor manufacturing process according to claim 1, wherein S103 specifically comprises the steps of: An annular boss with the thickness of 5mm is coaxially welded on the inner side of the cavity wall, the inner diameter of the boss is 0.05mm larger than the outer diameter of the fixing piece, and the perpendicularity of the boss end face and the axis of the cavity is less than or equal to 0.01mm and is used as an axial positioning spigot of the fixing piece; Turning a guide belt matched with the inner diameter of the boss on the outer circle of the fixing piece, wherein the length of the guide belt is 8mm, the fit clearance is 0.05mm, six M6 threaded blind holes are uniformly distributed on the end face of the fixing piece, the depth of each blind hole is 10mm, and the chamfer angle of an orifice is 0.5 multiplied by 45 degrees; The stainless steel countersunk head screw penetrates through the counter bore reserved in the chamber wall, the screw is screwed into the threaded blind hole of the fixing piece, the screw tightening torque is 12 N.m, and the countersunk hole is ground after welding, so that the fixing piece and the chamber wall are in a non-detachable rigid whole.
  6. 6. The method for crystal rotation in a semiconductor manufacturing process according to claim 1, wherein S104 specifically comprises the steps of: Multiplying the outer diameter value by a coefficient of 1.2 according to the maximum outer diameter data of the crystal to be grown, and calculating the minimum design diameter of the central hole, wherein the minimum design diameter is taken as a reference, the serial specification of the inner diameter of the rotor of the rotating motor and the minimum wall thickness strength requirement of the guide bearing are combined, rounded upwards to the nearest standard mechanical aperture serial value, and finally the execution diameter of the central hole is determined; The rotor of the rotating motor is designed into an annular structure with diameter around the center, so that a rotor core and permanent magnets or windings of the rotating motor are distributed on the periphery of a central hole in the radial direction, and the driving output of the rotating motor is transmitted to a hollow output shaft positioned at one end of the rotating motor through the annular rotor; designing a stepped bearing seat coaxial with the central hole, wherein the bearing seat main body is a thick-wall cylinder, and the diameter of an inner hole of the bearing seat main body is equal to or larger than the execution diameter to form a through section of the hole; The full-complement roller bearing is selected as the guide bearing, the guide bearing is pressed into the stepped hole in the bearing seat, and the minimum aperture of the bearing inner ring roller surface is ensured to be still larger than the execution diameter of the central hole.
  7. 7. The crystal rotation method in the semiconductor manufacturing process according to claim 1, wherein S105 specifically comprises the steps of: Machining an integral rigid mounting plate as a shared reference piece, and clamping and milling a first positioning plane for supporting the bottom of a rotary motor shell, a second positioning plane for contacting the bottom surface of a fixing piece and a central through hole for penetrating through a central hole on the mounting plate at one time to ensure that the three parts finish machining under the same clamping reference; Placing the rotating motor shell on a first positioning plane and pre-tightening the rotating motor shell by a clamp, and placing a fixing piece connected with the guide bearing on a second positioning plane; The laser centering instrument is used for enabling light beams to pass through an inner hole of an output shaft of the motor, namely a motor section with a central hole and an inner ring of a bearing, and adjusting the position of a motor shell in a horizontal plane until the offset of laser spots at the position of a target is less than 0.01mm so as to finish precise coaxial centering of the rotating motor and the guide bearing; On the premise of keeping the laser centering state, a thin copper stress adjusting pad is inserted and polished between the motor shell and the first positioning plane of the mounting plate and between the fixing piece and the second positioning plane of the mounting plate; And (3) adopting a drilling and reaming process, sequentially drilling and reaming out a positioning pin hole and a bolt hole for connecting the motor shell and the mounting plate, and a fixing piece and the mounting plate, and loading a positioning pin and a fastening bolt, and finally fixedly connecting the three into a whole to form the crystal rotating device main body.
  8. 8. The method for crystal rotation in a semiconductor manufacturing process according to claim 1, wherein S106 specifically comprises the steps of: Machining an external thread section at the end part of an output shaft of the rotating motor, and setting a shaft shoulder at the root part of the external thread section as an axial positioning reference surface of a crystal growth base; the center of the crystal growth base is provided with an internal threaded hole matched with the external threaded section, and an annular sinking table attached to the shaft shoulder is processed on the bottom surface of the base; And screwing the crystal growth base into the external thread section of the output shaft until the annular sinking table of the external thread section is tightly attached to the shaft shoulder, and using a lock nut or a stop washer to fix the base in a locking manner.
  9. 9. The crystal rotation method in the semiconductor manufacturing process according to claim 1, wherein S107 specifically comprises the steps of: An annular mounting groove is formed in the wall of the cavity, a metal sealing ring is embedded in the groove, and a flange plate at one end of the corrugated pipe is welded at the outer side of the groove, so that the flange plate and the wall of the cavity are in airtight connection through electron beam welding; The flange at the other end of the corrugated pipe is sleeved on the periphery of the fixing piece of the crystal rotating device main body, an O-shaped fluororubber sealing ring is arranged on the inner side of the flange, and the sealing surface is pressed by a fastening bolt; The whole chamber was subjected to bake-out and degassing treatment, and after heating at 150 ℃ for 12 hours, the whole chamber was evacuated to 1×10 -5 Pa or less using a molecular pump, and the leak rate of the bellows joint region was confirmed to be lower than 5×10 - ¹ 0 pa·m3/s by a helium mass spectrometer leak detector.
  10. 10. The method for crystal rotation in a semiconductor manufacturing process according to claim 1, wherein S108 specifically comprises the steps of: Before starting the rotating motor, adjusting a motor speed regulation knob or a control panel to a zero position, checking the connection fastening state of the guide bearing and the fixing piece, and confirming that the synchronous connection of the crystal growth base and the output shaft is reliable; After the rotating motor stably runs, the objective lens end of the industrial endoscope is aligned to the visual field area of the central hole, and the focal length and the aperture of the lens are adjusted, so that the crystal surface and the growth interface present clear images on the monitor, and the observation path and the axis of the hole are kept coaxial; during the continuous running process of the motor, the radial runout of the crystal rotating device body relative to the chamber wall is measured by using a displacement sensor, if the runout is found to be close to the limit value of +/-0.02 mm, the motor is stopped, the lubrication condition of the guide bearing is checked, the screw of the fixing piece is fastened, and the runout value is retested until the runout value is stabilized within the limit value after the restarting.

Description

Crystal rotation method in semiconductor preparation process Technical Field The invention belongs to the technical field of semiconductor preparation, and particularly relates to a crystal rotation method in a semiconductor preparation process. Background Semiconductor materials are the physical basis of modern electronic, optoelectronic and power devices, and their performance directly determines the main capabilities of chips, sensors, radio frequency modules and new energy power electronic systems. Among many semiconductor materials, single crystal silicon has been dominant for a long time, and wide forbidden band or compound semiconductors represented by silicon carbide (SiC), gallium nitride (GaN), gallium arsenide (GaAs) are rapidly being applied to high-end fields such as 5G communication, electric vehicles, rail transit, photovoltaic inverters, and the like, due to their advantages of high breakdown electric field, high thermal conductivity, high frequency response, and the like. The fabrication of these high performance semiconductor devices is highly dependent on the preparation of high quality single crystal substrates. Currently mainstream crystal growth techniques include Czochralski (CZ), physical Vapor Transport (PVT), bridgman (Bridgman), and Vertical Gradient Freeze (VGF) methods. Whichever method is used, crystal rotation is a key process parameter in regulating the growth process. Through rotation, the temperature gradient and concentration boundary layer in the melt or gas phase can be effectively dispersed, so that the solid-liquid (or solid-gas) interface tends to be flat, the generation of defects such as micropipes, dislocation, polytype inclusion and the like is reduced, and the doping uniformity is improved. However, the motor and the guide bearing are assembled respectively, and the motor vibration is easily transmitted to the guide bearing during operation without an effective rigid integrated positioning structure, so that the relative position of the motor and the guide bearing is offset, the swing amplitude of the output shaft exceeds the allowable range of crystal growth, and the crystal surface growth is uneven. And the central area of the rotating device is occupied by a transmission part or a supporting structure, the observation equipment can only observe obliquely from the side surface or the top of the cavity, is easy to be shielded by the rotating part, and cannot clearly capture the state of a key area for crystal growth, so that the process adjustment is delayed, and the crystal growth quality is affected. Disclosure of Invention According to the crystal rotation method in the semiconductor manufacturing process, the central hole meets the large-size crystal growth monitoring visual field, the guide bearing and the fixing piece cooperatively realize a large load, the corrugated pipe is sealed to maintain a vacuum environment, and the crystal growth quality is guaranteed. The method comprises the following steps: S101, configuring a rotating motor, and enabling an output shaft of the rotating motor to be in transmission connection with a crystal rotating carrier so as to drive crystals to be grown to execute rotating action; S102, configuring a guide bearing, sleeving the guide bearing outside an output shaft of a rotating motor, and supporting and guiding the radial movement of the output shaft in a direction; s103, positioning and fixing operation is carried out by adopting a fixing piece, and a guide bearing is connected with the chamber wall so as to stabilize the relative position of the rotating motor and the guide bearing; S104, planning a central hole in the axial center areas of the rotating motor and the guide bearing, so that the hole penetrates through the main areas of the rotating motor and the guide bearing, and the diameter of the hole is larger than 20% of the maximum outer diameter of the crystal to be grown; S105, integrating the rotating motor, the guide bearing and the fixing piece into a crystal rotating device main body, and enabling the main body to form fixed connection with the chamber wall through the fixing piece; S106, arranging a crystal growth base in a central hole of the crystal rotating device main body, so that the base and an output shaft of a rotating motor keep a synchronous rotating state to bear crystals to be grown; S107, performing sealing and isolating operation on the chamber, wrapping the crystal rotating device main body by adopting a corrugated pipe, and enabling the corrugated pipe to form sealing connection with the chamber wall so as to maintain the target environment atmosphere with the vacuum degree in the chamber less than or equal to 1 multiplied by 10 -5 Pa; S108, starting a rotating motor to operate so as to drive a crystal growth base to rotate, monitoring the crystal growth process through a visual field area of the central hole, and controlling the rotation radial deviation of a crystal rotating device main b