CN111952157B - Laser annealing device - Google Patents

Laser annealing device Download PDF

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Publication number
CN111952157B
CN111952157B CN202010828514.1A CN202010828514A CN111952157B CN 111952157 B CN111952157 B CN 111952157B CN 202010828514 A CN202010828514 A CN 202010828514A CN 111952157 B CN111952157 B CN 111952157B
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wafer
axis
laser
laser beam
stage
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CN111952157A (en
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张昆鹏
李纪东
张紫辰
侯煜
易飞跃
杨顺凯
李曼
张喆
王然
王瑜
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Beijing Zhongke Leite Electronics Co ltd
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Beijing Zhongke Leite Electronics Co ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/67005—Apparatus not specifically provided for elsewhere
    • H01L21/67011—Apparatus for manufacture or treatment
    • H01L21/67098—Apparatus for thermal treatment
    • H01L21/67115—Apparatus for thermal treatment mainly by radiation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/26—Bombardment with radiation
    • H01L21/263—Bombardment with radiation with high-energy radiation
    • H01L21/268—Bombardment with radiation with high-energy radiation using electromagnetic radiation, e.g. laser radiation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/67005—Apparatus not specifically provided for elsewhere
    • H01L21/67242—Apparatus for monitoring, sorting or marking
    • H01L21/67253—Process monitoring, e.g. flow or thickness monitoring
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/67005—Apparatus not specifically provided for elsewhere
    • H01L21/67242—Apparatus for monitoring, sorting or marking
    • H01L21/67288—Monitoring of warpage, curvature, damage, defects or the like
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
    • H01L22/10—Measuring as part of the manufacturing process
    • H01L22/12—Measuring as part of the manufacturing process for structural parameters, e.g. thickness, line width, refractive index, temperature, warp, bond strength, defects, optical inspection, electrical measurement of structural dimensions, metallurgic measurement of diffusions
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
    • H01L22/20—Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps
    • H01L22/24—Optical enhancement of defects or not directly visible states, e.g. selective electrolytic deposition, bubbles in liquids, light emission, colour change
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L22/00—Testing or measuring during manufacture or treatment; Reliability measurements, i.e. testing of parts without further processing to modify the parts as such; Structural arrangements therefor
    • H01L22/20—Sequence of activities consisting of a plurality of measurements, corrections, marking or sorting steps
    • H01L22/26—Acting in response to an ongoing measurement without interruption of processing, e.g. endpoint detection, in-situ thickness measurement

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  • Recrystallisation Techniques (AREA)
  • Container, Conveyance, Adherence, Positioning, Of Wafer (AREA)

Abstract

The invention provides a laser annealing device, comprising: the wafer annealing apparatus includes a stage holding a wafer, a laser assembly emitting a laser beam toward the wafer to anneal the wafer, the wafer having a first side facing away from the stage and a second side facing toward the stage. The laser device further comprises a height indicator arranged above the objective table and a three-axis galvanometer system arranged between the laser assembly and the wafer. The height measuring instrument measures the height difference change between different positions on the first surface of the wafer and reference surfaces set by the height measuring instrument; the three-axis galvanometer system moves the laser beam emitted by the laser assembly to adjust the focal position of the laser beam focused on the wafer. The three-axis galvanometer system is controlled to keep a focus on a layer structure which is away from the first surface and has a set depth on the wafer according to the change of the height difference measured by the height measuring instrument. The focal position of the laser beam is adjusted up and down according to the convex-concave fluctuation of the first surface of the wafer, and the position accuracy of wafer annealing is improved.

Description

Laser annealing device
Technical Field
The invention relates to the technical field of wafer manufacturing, in particular to a laser annealing device.
Background
With the progress and development of science and technology, laser has been used as a tool in various industries. Due to the characteristics of high brightness and high intensity of laser, and the size of the laser focus can be focused to micron order by the focusing lens, the laser processing technology is favored in industries with high precision processing requirements, especially for the technology of wafer manufacturing in the semiconductor industry.
Initially, annealing of the wafers is performed in a furnace containing a number of wafers supported in a rack. Electrical energy is supplied to the resistive heater elements in the furnace walls to heat them to a temperature near the desired process temperature. The wafer eventually reaches a temperature substantially equal to the furnace wall. After annealing at the elevated temperature for the desired length of time, power is no longer supplied to the resistance heaters, so that the walls gradually cool and the wafer also gradually cools. Although the required heat treatment time may be relatively short, both the heating rate and the cooling rate are relatively slow, on the order of about 15 deg.C/min. These longer times during elevated temperatures significantly increase the thermal budget required for annealing. The fine features and thin layers in advanced integrated circuits require a reduction in thermal budget.
Disclosure of Invention
The invention provides a laser annealing device, which is used for solving the problem that a depth layer of laser annealing fluctuates up and down due to the fact that the surface of a wafer is not flat.
The invention provides a laser annealing device, comprising: the wafer annealing apparatus includes a stage holding a wafer, and a laser assembly emitting a laser beam toward the wafer to anneal the wafer, wherein the wafer has a first side facing away from the stage and a second side facing toward the stage. The laser device further comprises a height indicator arranged above the objective table and a three-axis galvanometer system arranged between the laser assembly and the wafer. The height measuring instrument measures height difference changes between different positions on the first surface of the wafer and reference surfaces set by the height measuring instrument; the three-axis galvanometer system moves the laser beam emitted by the laser assembly to adjust the focal position of the laser beam focused on the wafer. The device also comprises a control device, and the control device controls the triaxial galvanometer system to keep the focus on a layer structure which is at a set depth from the first surface on the wafer according to the change of the height difference measured by the height measuring instrument.
In the scheme, the height measuring instrument, the three-axis vibrating mirror system and the control device are arranged, so that the height difference change between different positions of the first surface of the wafer and the reference surface is measured at any time before and during annealing by the height measuring instrument, and the control device controls the three-axis vibrating mirror system to enable the laser beam emitted by the laser assembly to be always focused on the layer structure with the set depth from the first surface on the wafer. The focal position of the laser beam can be adjusted up and down according to the convex-concave fluctuation of the first surface of the wafer, and the convex-concave fluctuation of the surface of the wafer is prevented, so that the focal position of the laser beam fluctuates up and down at different depth layers of the wafer, the position accuracy of annealing the wafer is improved, and the annealing effect is improved.
In one specific embodiment, the first side of the wafer has a region to be annealed, the region to be annealed has three set points that are no longer collinear, and the reference plane for the altimeter is a plane parallel to the plane in which the three set points lie. Before annealing, the altimeter firstly picks up the elevations of three set points on the region to be annealed of the first surface to determine a reference surface, and then in the annealing process, the focal point position of the laser beam is adjusted according to the height difference change of different positions on the region to be annealed from the reference surface, so that the focal point is kept on a layer structure with a set depth from the first surface, and meanwhile, the reference surface is determined.
In one specific embodiment, the object stage is provided with a reference surface for placing the wafer; the three-axis galvanometer system adjusts the focus position of a laser beam focused on a wafer in three mutually perpendicular directions of an x axis, a y axis and a z axis, the x axis and the y axis are parallel to a reference surface, and the z axis is perpendicular to the reference surface, so that the three-axis galvanometer system can be adjusted conveniently.
In a specific embodiment, the control device controls the z-axis of the three-axis galvanometer system to move to focus on the focal point of the laser beam focused on the wafer according to the change of the height difference measured by the height gauge, so that the focal point is kept on the layer structure which is at the set depth from the first surface, and the focal point can be kept on the layer structure which is at the set depth from the first surface of the wafer only by adjusting the z-axis of the three-axis galvanometer system.
In a specific embodiment, the direction parallel to the reference plane upwards is the positive direction of the z-axis, and the distance between the reference plane of the altimeter and the plane in which the three set points are located is H; when the height difference measured by the height measuring instrument is larger than H, the control device controls the negative direction of the z-axis of the three-axis galvanometer system to move the laser beam to focus on the focus of the wafer so as to keep the focus on a layer structure which is positioned at a set depth away from the first surface of the wafer; when the height difference measured by the height measuring instrument is smaller than H, the control device controls the positive direction of the z axis of the three-axis galvanometer system to move the laser beam to focus on the focus of the wafer so as to keep the focus on the layer structure which is positioned at the set depth away from the first surface of the wafer. So as to maintain the focal point of the laser beam on the layer structure at a set depth from the first side of the wafer.
In a specific embodiment, the laser annealing device further comprises a processing cavity for accommodating the object stage, wherein a window for enabling a laser beam emitted by the laser component to be incident on the wafer is arranged on the processing cavity; the height indicator is located outside the processing cavity and opposite to the window, and the height indicator measures height difference changes between reference surfaces, which are arranged on the first surface of the wafer and are different in position from the height indicator, through the window. Through setting up the altimeter outside the processing chamber to reduce the structure in the processing chamber, be convenient for dwindle the space in the processing chamber, reduce the gaseous time of replacement processing intracavity, improve annealing efficiency.
In one embodiment, the window is opposite the position of the wafer held on the stage and the window is larger than the wafer so that the altimeter can measure each position on the first side of the wafer through the window.
In a specific embodiment, a position outside the processing cavity and opposite to the window is provided with a moving platform capable of moving in three mutually perpendicular directions, and the height indicator is arranged on the moving platform so as to measure the height difference change between reference surfaces arranged at different positions and distances of the first surface of the wafer.
In a specific embodiment, a CCD camera (charge coupled device camera) for picking up an image on the first surface of the wafer is further disposed on the moving platform, so as to observe the annealing condition in real time.
In a specific embodiment, a mechanical arm for overturning the wafer held on the object stage is further arranged in the processing cavity, so that after one surface of the wafer is annealed, the wafer is automatically overturned to anneal the other surface of the wafer, and meanwhile, gas in the processing cavity does not need to be replaced in the middle, and the annealing efficiency is improved.
Drawings
Fig. 1 is a schematic structural diagram of a laser annealing apparatus according to an embodiment of the present invention;
FIG. 2 is a schematic top view of a wafer held on a stage according to an embodiment of the present invention;
FIG. 3 is a cross-sectional view of section A-A of FIG. 2;
fig. 4 is a schematic structural diagram of a processing chamber and a motion platform according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of another laser annealing apparatus according to an embodiment of the present invention.
Reference numerals are as follows:
10-object stage 11-datum plane 12-processing cavity 13-window
20-wafer 21-first side 211-region to be annealed 212-setpoint
22-second side 23-layer structure 30-laser assembly 31-laser beam
40-altimeter 41-reference surface 50-three-axis galvanometer system
60-control device 70-motion platform
81-CCD camera 82-resistance measuring instrument 83-pyrometer
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
To facilitate understanding of the laser annealing apparatus provided in the embodiment of the present invention, an application scenario of the laser annealing apparatus provided in the embodiment of the present invention is first described below, where the laser annealing apparatus is used for annealing a wafer in a semiconductor manufacturing process. The laser annealing apparatus will be described in detail below with reference to the drawings.
Referring to fig. 1 and 3, a laser annealing apparatus according to an embodiment of the present invention includes: a stage 10 holding a wafer 20, and a laser assembly 30 emitting a laser beam 31 toward the wafer 20 to anneal the wafer 20, wherein the wafer 20 has a first side 21 facing away from the stage 10 and a second side 22 facing toward the stage 10. Also included is a height gauge 40 disposed above the stage 10, and a three-axis galvanometer system 50 disposed between the laser assembly 30 and the wafer 20. Wherein, the height gauge 40 measures the height difference change between different positions on the first surface 21 of the wafer 20 and the reference surface 41 set by the height gauge 40; the three-axis galvanometer system 50 moves the laser beam 31 emitted by the laser assembly 30 to adjust the focal position at which the laser beam 31 is focused on the wafer 20. The three-axis galvanometer system 50 is controlled by the control device 60 to maintain a focus on the layer structure 23 on the wafer 20 at a set depth from the first surface 21 according to the height difference change measured by the height gauge 40.
In the above solution, the height gauge 40, the three-axis galvanometer system 50 and the control device 60 are arranged to measure the height difference change between different positions of the first surface 21 of the wafer 20 and the reference surface 41 before and during annealing by the height gauge 40, and the control device 60 controls the three-axis galvanometer system 50 to make the laser beam 31 emitted by the laser module 30 always focus on the layer structure 23 on the wafer 20, which is at a set depth from the first surface 21. The focal position of the laser beam 31 can be adjusted up and down according to the convex-concave fluctuation of the first surface 21 of the wafer 20, so that the focal position of the laser beam 31 can be prevented from fluctuating up and down at different depth layers of the wafer 20 due to the convex-concave fluctuation of the surface of the wafer 20, the position accuracy of annealing the wafer 20 is improved, and the annealing effect is improved. The arrangement of the above-mentioned devices will be described in detail with reference to the accompanying drawings.
Referring to fig. 1, 2 and 4, a stage 10 is provided to hold a wafer 20 on the stage 10. The stage 10 may be provided with a vacuum suction hole for sucking the wafer 20, so as to suck the wafer 20. Referring to fig. 3, the stage 10 has an end surface for supporting the wafer 20, which is a reference surface 11 for determining the orientation of three axes in the three-axis galvanometer system 50. Referring to fig. 2 and 3, for the convenience of the following description, two mutually perpendicular straight lines in the reference plane 11 are taken as the x axis and the y axis in the spatial rectangular coordinate system, and the intersection point of the two mutually perpendicular straight lines is taken as the origin. A straight line perpendicular to the reference surface 11 is taken as a z-axis, wherein an upward direction parallel to the reference surface 11 is a positive direction of the z-axis, and a downward direction parallel to the reference surface 11 is a negative direction of the z-axis.
Referring to fig. 1 and 4, a processing chamber 12 may also be provided, and the stage 10 is housed within the processing chamber 12. The processing chamber 12 may be a housing structure with a hollow cavity, and the object stage 10 may be fixed in the processing chamber 12, or may be slidably assembled in the processing chamber 12 through a sliding rail assembly. Of course, it is preferable that the stage 10 is fixedly mounted in the processing chamber 12, and in this case, it is not necessary to provide a slide rail assembly and a driving assembly for driving the stage 10 to move in the processing chamber 12, so that the structure in the processing chamber 12 is reduced, and in application, the volume of the processing chamber 12 can be made sufficiently small, and the gas replacement time in the processing chamber 12 can be shortened. Referring to fig. 1 and 4, the laser assembly 30 may be disposed above the process chamber 12, and a window 13 is disposed on the process chamber 12, and a laser beam 31 emitted from the laser assembly 30 is incident on the wafer 20 through the window 13. The window 13 may be disposed in the form of an optical window 13 lens, specifically, an opening is formed above the processing chamber 12, and an optical window 13 lens is hermetically mounted at the opening, so that the laser beam 31 emitted by the laser assembly 30 can be incident into the processing chamber 12. The window 13 can be positioned opposite the wafer 20 held on the stage 10 and the window 13 is larger than the wafer 20, in which case the laser assembly 30 can anneal every position on the wafer 20 and the height gauge 40 can measure every position on the first side 21 of the wafer 20 through the window 13 even when the stage 10 is fixed in the process chamber 12.
The wafer 20 has two opposite surfaces, one of which is a front surface and is used for arranging a plating structure 23 such as a doping layer, a transistor, a metal layer, a capacitor and the like; the other side is the back side. The laser processing apparatus may anneal the front surface of the wafer 20, or may anneal the back surface of the wafer 20. During the front side annealing of the wafer 20, the lattice defects and internal stress in the wafer 20 are eliminated, so as to restore the integrity of the lattice; the implanted dopant atoms are allowed to diffuse to the substitutional sites, resulting in electrical characteristics, referred to as wafer 20 activation annealing. The back surface of the wafer 20 is plated with a metal structure, and the metal structure plated on the back surface of the wafer 20 is annealed to reduce the resistance value and improve the consistency. Referring to fig. 1 and 3, a surface of the wafer 20 away from the stage 10 is a first surface 21 of the wafer 20, i.e., an upper surface of the wafer 20 in fig. 1 and 3 is the first surface 21 of the wafer 20. The first surface 21 may be the front surface of the wafer 20, or may be the back surface of the wafer 20. The surface of the wafer 20 facing the stage 10 is a second surface 22, i.e., the lower surface of the wafer 20 in fig. 1 and 3 is the second surface 22 of the wafer 20. When the first surface 21 of the wafer 20 is the front surface of the wafer 20, the second surface 22 of the wafer 20 is the back surface of the wafer 20; when the first surface 21 of the wafer 20 is the back surface of the wafer 20, the second surface 22 of the wafer 20 is the front surface of the wafer 20. The first surface 21 of the wafer 20 is an annealing surface of the laser annealing apparatus, and the surface of the first surface 21 may be annealed, or the layer structure 23 having a predetermined depth from the first surface 21 inside the wafer 20 may be annealed. Fig. 3 shows a schematic illustration of annealing a layer structure 23 of a set depth within the wafer 20.
A robot may also be provided in the process chamber 12 for placing the wafer 20 on the stage 10 or removing the wafer from the stage 10. The robot may also be used to turn the wafer 20 over after annealing one side of the wafer 20 is completed to anneal the other side of the wafer 20. In the overturning process, the processing cavity 12 does not need to be opened, so that gas in the processing cavity 12 does not need to be replaced in the middle process, and the annealing efficiency is improved.
When the altimeter 40 is provided, the altimeter 40 may be a direct altimeter 40 of the prior art. Referring to fig. 1 and 4, it may be disposed outside the process chamber 12 with the height gauge 40 opposite the window 13. The height gauge 40 is capable of measuring a change in height difference between different locations on the first side 21 of the wafer 20 through the window 13 from a reference surface 41 on which the height gauge 40 is disposed. Through setting up altimeter 40 outside processing chamber 12 to reduce the structure in processing chamber 12, be convenient for dwindle the space in processing chamber 12, reduce the time of the interior gas of replacement processing chamber 12, improve annealing efficiency.
Referring to fig. 1 and 4, a moving platform 70 capable of moving in three mutually perpendicular directions may be disposed outside the processing chamber 12 and opposite to the window 13, and the height gauge 40 is disposed on the moving platform 70, so that the height gauge 40 measures a change in a height difference between the reference surfaces 41 disposed at different positions and distances from the first surface 21 of the wafer 20. An arrangement of three linear motors may be employed to effect translational movement of the motion stage 70 in three mutually perpendicular dimensions. The method can also be realized by adopting a mechanical arm.
Referring to fig. 2 and 3, the wafer 20 has a region 211 to be annealed on the first surface 21, and the laser annealing apparatus can anneal the surface of the region 211 to be annealed, at this time, the set depth is zero; the annealing may be performed at a certain depth in the region 211 to be annealed, and at this time, the annealing may be performed on the layer structure 23 at a certain depth in the region 211 to be annealed, which is adjusted according to the set depth.
As shown in fig. 2, there are three set points 212 on the zone 211 to be annealed, which are no longer collinear, the reference plane 41 on which the altimeter 40 is arranged being a plane parallel to the plane on which the three set points 212 lie. In use, the height gauge 40 first picks up the elevations of the three set points 212 on the region 211 to be annealed on the first side 21 of the wafer 20 to determine the reference plane 41 before annealing, and then adjusts the position of the focal point of the laser beam 31 during annealing in accordance with the change in the height difference from the reference plane 41 at different locations on the region 211 to be annealed so that the focal point remains at a set depth from the first side 21 of the layer structure 23 and so that the reference plane 41 is determined.
For example, before annealing, the altimeter 40 picks up three setpoints 212 on three no longer collinear regions 211 of the first side 21 of the wafer 20 to be annealed. Thereafter, the altimeter 40 measures the elevation of each setpoint 212 from a plane above the wafer 20 that is parallel to the datum plane 11 of the stage 10 by moving the altimeter 40 vertically above each setpoint 212 to measure the elevation of each setpoint 212. The altimeter 40 can set a reference surface 41 according to the position coordinate information of the three set points 212 and the elevation information of each set point 212, and the reference surface 41 is parallel to the plane of the three set points 212. In particular, with reference to fig. 3, the reference plane 41 may be at a distance H from the plane in which the three set points 212 lie. The reference surface 41 may be parallel to the datum surface 11 on the stage 10, in which case the three set points 212 lie in a plane parallel to the datum surface 11 on the stage 10. The reference surface 41 may also be non-parallel to the reference surface 11 on the stage 10, in which case the three set points 212 lie in a plane that is not parallel to the reference surface 11 on the stage 10.
During the annealing process, the height gauge 40 first measures the height of a certain annealing point on the region 211 to be annealed from the reference surface 41, and the measured height of a certain annealing point from the reference surface 41 refers to the distance of the annealing point from the reference surface 41 in the vertical direction (or z-axis direction). It should be noted that the height of the annealing point from the reference surface 41 may or may not be equal to the perpendicular distance of the annealing point from the reference surface 41. When the reference surface 41 is parallel to the datum surface 11 on the stage 10, then the height of the annealing point from the reference surface 41 is equal to the perpendicular distance of the annealing point from the reference surface 41; when the reference surface 41 is not parallel to the datum surface 11 on the stage 10, then the height of the annealing point from the reference surface 41 is not equal to the perpendicular distance of the annealing point from the reference surface 41.
After the height gauge 40 measures the height of a certain annealing point of the region to be annealed 211 from the reference surface 41, the height gauge 40 transmits the information to the control device 60. The control device 60 compares the measured height value with the magnitude of H to issue different commands for adjusting the three-axis galvanometer system 50 to maintain the focal point of the laser beam 31 at a layer structure 23 at a set depth from the first surface 21 of the wafer 20. Specifically, when annealing the annealing point of the region to be annealed 211, the focal point of the laser beam 31 is located on the layer structure 23 at a set depth from the annealing point. That is, the annealing point mentioned above only refers to a point of the region 211 to be annealed on the first side 21 of the wafer 20, that is, the annealing point is located on the surface of the wafer 20. Annealing the annealing point means annealing a point on the layer structure 23 at a predetermined depth immediately below the annealing point in the vertical direction.
When the control device 60 is provided, the control device 60 may be a terminal device such as an upper computer, an industrial personal computer, or the like, and the control device 60 may be connected to the altimeter 40 and the three-axis galvanometer system 50 in a wired or wireless communication manner, so that the control device 60 performs information interaction with the altimeter 40 and the three-axis galvanometer system 50, respectively.
When the three-axis galvanometer system 50 is installed, the three-axis galvanometer system 50 adjusts the focal position of the laser beam 31 focused on the wafer 20 in three mutually perpendicular directions of the x axis, the y axis and the z axis, wherein the x axis, the y axis and the z axis are installed in the same coordinate system as the spatial rectangular coordinate system, or the three axes are respectively installed in parallel, so as to adjust the three-axis galvanometer system 50.
When the control device 60 controls the adjustment of the three-axis galvanometer system 50, the control device 60 may control the z-axis of the three-axis galvanometer system 50 to move the focal point focused on the laser beam 31 focused on the wafer 20 according to the height difference change measured by the height gauge 40, so that the focal point is maintained on the layer structure 23 located at the set depth from the first surface 21, and the focal point position may be maintained on the layer structure 23 located at the set depth from the first surface 21 of the wafer 20 only by adjusting the z-axis of the three-axis galvanometer system 50.
For example, referring to fig. 3, when the height difference H1 measured by the height gauge 40 is greater than H, the control device 60 controls the z-axis of the three-axis galvanometer system 50 to move the laser beam 31 to a negative direction of the z-axis to focus the focal point on the wafer 20, so that the focal point is maintained on the layer structure 23 located at a set depth from the first surface 21 of the wafer 20. When the height difference measured by the height gauge 40 is smaller than H2 and smaller than H, the control device 60 controls the z-axis of the three-axis galvanometer system 50 to move the focal point of the laser beam 31 focused on the wafer 20 in the positive direction of the z-axis so that the focal point is maintained on the layer structure 23 located at a set depth from the first surface 21 of the wafer 20. Of course, when the height difference measured by the height gauge 40 is equal to H, the control device 60 may simply hold the original z-axis setting information. In this way, the focal point of the laser beam 31 is maintained at a set depth of the layer structure 23 from the first side 21 of the wafer 20.
Referring to fig. 5, a CCD camera 81 for picking up an image on the first side 21 of the wafer 20 may also be provided on the motion stage 70 to facilitate real-time observation of the annealing. And the CCD camera 81 is arranged outside the processing cavity 12, so that the structure in the processing cavity 12 is reduced, the space in the processing cavity 12 is convenient to reduce, the time for replacing the gas in the processing cavity 12 is reduced, and the annealing efficiency is improved.
Referring to fig. 5, a resistance measuring instrument 82 for measuring the resistance of a certain circuit and device on the layer structure 23 of the first side 21 of the wafer 20 may be further disposed on the moving platform 70, so as to know the resistance of a certain circuit and device at any moment during the annealing process, and know the annealing effect. And the resistance measuring instrument 82 is arranged outside the processing cavity 12, so that the structure in the processing cavity 12 is reduced, the space in the processing cavity 12 is conveniently reduced, the time for replacing the gas in the processing cavity 12 is reduced, and the annealing efficiency is improved.
Referring to fig. 5, a pyrometer 83 may be further disposed on the moving platform 70 for measuring a position on the layer structure 23 of the first side 21 of the wafer 20, so as to know the temperature of a position at any time during the annealing process, and to know the annealing effect. And the pyrometer 83 is arranged outside the processing cavity 12, so that the structure in the processing cavity 12 is reduced, the space in the processing cavity 12 is conveniently reduced, the time for replacing the gas in the processing cavity 12 is shortened, and the annealing efficiency is improved.
In addition, referring to fig. 1 and 5, a light-passing hole may be disposed on the stage 10, and a lower window may be further disposed on the processing cavity 12; and the window 13, the light-admitting aperture and the lower window are at least partially positioned relative to each other so that the laser beam 31 can be incident from the window 13 into the process chamber 12 and then pass through the light-admitting aperture and exit the process chamber 12 through the lower window. And a measuring instrument assembly arranged outside the processing cavity 12 and opposite to the lower window, wherein the measuring instrument assembly is used for measuring and analyzing the light beam 31 emitted out of the processing cavity 12 from the lower window. By fixing the object stage 10 in the processing chamber 12, the object stage 10 is provided with a light-passing hole, the light-passing hole is opposite to at least part of the window 13 and the lower window on the processing chamber 12, and a measuring instrument assembly is set at the position opposite to the lower window outside the processing chamber 12. Before the wafer 20 is placed on the stage 10, the laser beam 31 passes through the window 13, the light-passing hole and the lower window in sequence, and then the measuring instrument assembly measures and analyzes the laser beam 31. Compared with the structure in the prior art, the scheme of the invention does not need to arrange a reflector in the processing cavity 12, and does not need to arrange a slide rail assembly and a driving assembly for driving the objective table 10 to move, thereby reducing the structure in the processing cavity 12 and ensuring that the volume of the processing cavity 12 is small enough. Since each wafer entry and exit destroys the atmosphere in the process chamber 12 when the wafer 20 is a wafer, gas replacement is required. The smaller the cavity volume in the processing cavity 12 is, the shorter the gas replacement time is, and by adopting the scheme of the invention, the volume of the processing cavity 12 can be reduced, the gas replacement time in the processing cavity 12 can be shortened, and the laser processing efficiency can be improved.
A window 13 is provided above the process chamber 12, and in the example shown in fig. 1 and 5, the window 13 is provided above the process chamber 12, and the stage 10 is positioned opposite to the window 13 so that the laser beam 31 incident into the process chamber 12 from the window 13 can be irradiated onto the wafer 20 on the stage 10. The stage 10 is further provided with a light-transmitting hole which is opposed to at least a part of the window 13, so that the laser beam 31 can enter the processing chamber 12 through the window 13 and then enter the light-transmitting hole when the wafer 20 is not placed on the stage 10. Referring to fig. 1 and 5, the light-passing hole allows a laser beam 31 to enter from one end near the window 13 and exit from the other end. In the example shown in fig. 1 and 5, a lower window is further provided below the processing chamber 12, and the lower window is at least partially opposed to the light transmitting hole so that the laser beam 31 emitted from the light transmitting hole can enter the lower window and exit the processing chamber 12 from the lower window. When the window 13 and the lower window are specifically arranged, two openings may be respectively formed above and below the processing cavity 12 in the window 13 and the lower window, at least part of the two openings are opposite to each other, and both the two openings are opposite to at least part of the light through hole on the object stage 10, and then optical window lenses are respectively installed at the two openings, so that the laser beam 31 can pass through the two openings, and meanwhile, a sealed cavity is formed in the processing cavity 12.
As shown in fig. 1 and 5, a measuring instrument assembly is disposed outside the process chamber 12 and opposite the lower window, and measures and analyzes a light beam 31 emitted from the lower window out of the process chamber 12. In application, before the wafer 20 is placed on the stage 10, the laser beam 31 sequentially passes through the window 13, the light-passing hole and the lower window, and then is emitted from the lower window, and the measuring instrument assembly measures and analyzes the laser beam 31. Compared with the structure in the prior art, the scheme of the invention does not need to arrange a reflector in the processing cavity 12, reduces the structure in the processing cavity 12 and can make the volume of the processing cavity 12 small enough. Since each wafer entry and exit destroys the atmosphere in the process chamber 12 when the wafer 20 is a wafer, gas replacement is required again. The smaller the cavity volume in the processing cavity 12 is, the shorter the gas replacement time is, and by adopting the scheme of the invention, the volume of the processing cavity 12 can be reduced, the gas replacement time in the processing cavity 12 can be shortened, and the laser processing efficiency can be improved.
In particular arrangements of the gauge assembly, which may include a beam quality analyzer and/or a power meter, detection analysis of the energy and quality of the laser beam 31 is achieved. Specifically, the measuring instrument assembly may only have a beam quality analyzer, may also only have a power meter, and may also have both a beam quality analyzer and a power meter, thereby implementing analysis and detection of the energy and quality of the laser beam 31.
Referring to fig. 2, a motion platform capable of moving in at least one dimension may also be provided outside the process chamber 12 opposite the lower window, with the gauge assembly being disposed on the motion platform so as to move the gauge assembly to a position suitable for detecting the laser beam 31. For example, the motion platform may drive the measuring instrument assembly to move up and down in a direction perpendicular to the light beam 31 of the laser; the motion platform can also drive the measuring instrument component to move left and right and back and forth in a plane vertical to the laser beam 31; the motion platform can also drive the measuring instrument component to rotate along a certain direction. That is, it is within the scope of the present invention as long as the motion platform can drive the measuring instrument assembly to move in at least one dimension. When the motion platform is specifically set, the motion platform may adopt an arrangement mode of one or more linear motors to realize the translational motion of the motion platform in at least one dimension. A rotating mechanism can be arranged on the linear motor to realize the rotation of the moving platform in a certain dimension. And the method can also be realized by adopting a mechanical arm mode.
A pyrometer may also be disposed on the motion platform below the processing chamber 12 to facilitate temperature measurement of the surface of the wafer 20 facing the stage 10, so as to achieve real-time monitoring of the lower surface of the wafer 20 during laser annealing, facilitate improved detection of the temperature of the lower surface of the wafer 20 during laser annealing, and thus adjust the relevant parameters and improve the control of the laser annealing quality.
By arranging the height gauge 40, the three-axis galvanometer system 50 and the control device 60, the height gauge 40 constantly measures the height difference change between different positions of the first surface 21 of the wafer 20 and the reference surface 41 before and during annealing, and the control device 60 controls the three-axis galvanometer system 50 to enable the laser beam 31 emitted by the laser assembly 30 to be always focused on the layer structure 23 with the set depth from the first surface 21 on the wafer 20. The focal position of the laser beam 31 can be adjusted up and down according to the convex-concave fluctuation of the first surface 21 of the wafer 20, so that the focal position of the laser beam 31 can be prevented from fluctuating up and down at different depth layers of the wafer 20 due to the convex-concave fluctuation of the surface of the wafer 20, the position accuracy of annealing the wafer 20 is improved, and the annealing effect is improved.
The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (7)

1. A laser annealing device, comprising:
a stage holding a wafer, wherein the wafer has a first side facing away from the stage and a second side facing the stage;
a laser assembly that emits a laser beam to the wafer to anneal the wafer;
the height measuring instrument is arranged above the object stage and used for measuring height difference changes between different positions on the first surface of the wafer and a reference surface arranged on the height measuring instrument;
the three-axis galvanometer system is arranged between the laser assembly and the wafer and moves a laser beam emitted by the laser assembly so as to adjust the focus position of the laser beam focused on the wafer;
the control device is used for controlling the three-axis galvanometer system to keep the focus on a layer structure which is arranged on the wafer and has a set depth from the first surface according to the change of the height difference measured by the altimeter;
a processing cavity for accommodating the objective table, wherein a window for enabling a laser beam emitted by the laser component to be incident on the wafer is arranged on the processing cavity;
the first surface of the wafer is provided with a region to be annealed, the region to be annealed is provided with three set points which are not on the same straight line, and a reference surface arranged by the altimeter is a plane parallel to a plane where the three set points are located; a motion platform capable of moving in three mutually perpendicular directions is arranged at a position outside the processing cavity and opposite to the window, and the altimeter is arranged on the motion platform; the height indicator is positioned outside the processing cavity and opposite to the window,
and the height gauge measures the height difference change between different positions on the region to be annealed of the first surface of the wafer and a reference surface arranged by the height gauge through the window.
2. The laser annealing apparatus according to claim 1, wherein the stage has a reference surface on which the wafer is placed;
and the three-axis galvanometer system adjusts the focus position of the laser beam focused on the wafer in three mutually perpendicular directions of an x axis, a y axis and a z axis, the x axis and the y axis are both parallel to the reference surface, and the z axis is perpendicular to the reference surface.
3. The laser annealing apparatus of claim 2, wherein the control means controls the z-axis of the three-axis galvanometer system to move a focal point focused on the wafer by the laser beam according to the height difference variation measured by the height gauge, so that the focal point is maintained on the layer structure at a set depth from the first surface.
4. The laser annealing device according to claim 3, wherein the upward direction parallel to the reference surface is a positive direction of the z-axis; the distance between a reference surface set by the altimeter and the plane where the three set points are located is H;
when the height difference measured by the height gauge is larger than H, the control device controls the negative direction of the z-axis of the three-axis galvanometer system to move the laser beam to focus on the focal point on the wafer so as to enable the focal point to be kept on the layer structure which is located at a set depth away from the first surface;
when the height difference measured by the height gauge is smaller than H, the control device controls the positive direction of the z-axis of the three-axis galvanometer system to move the focus of the laser beam focused on the wafer so as to enable the focus to be kept on the layer structure which is away from the first surface and has the set depth.
5. The laser annealing apparatus according to claim 1, wherein the window is opposed to a position of the wafer held on the stage, and a size of the window is larger than a size of the wafer.
6. The laser annealing apparatus of claim 1 wherein the motion stage is further provided with a CCD camera for picking up an image on the first side of the wafer.
7. The laser annealing apparatus of claim 1 wherein a robot for inverting the wafer held on the stage is further provided in the processing chamber.
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