Laser annealing arc scanning method and laser annealing device

Abstract

An embodiment of the present invention provides a laser annealing arc scanning method and a laser annealing device, comprising: providing a wafer; forming an annealing scanning trajectory; wherein the annealing scanning trajectory includes multiple arc-shaped spot trajectories arranged along the y direction, each of the spot trajectories includes multiple spots arranged along the x direction, forming the mth spot in the (i+1)th spot trajectory and the nth spot in the (i)th spot trajectory to be tangent, where i, m, and n are all positive integers; along the x direction, the distance between the mth spot in the (i+1)th spot trajectory and the nth spot in the (i)th spot trajectory is equal to the length of the spot along the x direction; performing laser scanning according to the annealing scanning trajectory to complete annealing of the wafer. An embodiment of the present invention provides a laser annealing arc scanning method and a laser annealing device, which, through the planning of the spot trajectories, allows multiple annealing to be completed in areas with insufficient annealing time, thereby improving the uniformity of the wafer surface temperature.

Description

Technical Field

[0001] The present invention relates to photolithography technology, and in particular to a laser annealing arc scanning method and a laser annealing device. Background Art

[0002] Millisecond-level annealing technology is primarily used in laser annealing processes for ultra-shallow junction and silicide processes at 45nm and below process nodes in the front-end of ICs. Laser annealing involves scanning the laser across the wafer, generating heat in a small area for a very short time, keeping the temperature just below the melting point of silicon. Cooling is also completed in a very short time, resulting in an overall dwell time of only a few hundred microseconds, making it a more efficient, diffusion-free process.

[0003] As process nodes shrink, IC manufacturing places stringent demands on wafer stress and warpage. Stress can damage carefully designed strained channel structures, making it difficult for lithography engineers to meet the stringent overlay accuracy requirements of double patterning schemes. Wafer warpage undoubtedly exacerbates the difficulty of overlay control. Laser annealing has been shown to reduce wafer stress. This is because when a point defect diffuses into a nucleus, dislocation forms. If the dwell time is extremely short, the temperature difference that drives the diffusion dissipates before the dislocation occurs. While millisecond-level annealing techniques can reduce dwell times to hundreds of microseconds, traditional annealing schemes using CO2 laser sources, with their deep absorption depth and large heat-affected zone, introduce significant annealing stress. Exploring arc scanning as an alternative to traditional linear scanning schemes addresses the increased wafer stress associated with aligning the laser scanning direction with the wafer lattice. However, arc scanning can result in insufficient annealing time in some areas, leading to poor temperature uniformity across the wafer surface. Summary of the Invention

[0004] The embodiment of the present invention provides a laser annealing arc scanning method and a laser annealing device, which can complete multiple annealing in the area with insufficient annealing time through planning of the light spot trajectory, thereby improving the uniformity of the wafer surface temperature.

[0005] In a first aspect, an embodiment of the present invention provides a laser annealing arc scanning method, comprising:

[0006] Provide wafers;

[0007] forming an annealing scanning track; wherein the annealing scanning track includes a plurality of arc-shaped light spot tracks arranged along the y direction, each of the light spot tracks includes a plurality of light spots arranged along the x direction, the mth light spot in the (i+1)th light spot track is tangent to the nth light spot in the (i)th light spot track, and i, m, and n are all positive integers; along the x direction, the distance between the mth light spot in the (i+1)th light spot track and the nth light spot in the (i)th light spot track is equal to the length of the light spot along the x direction;

[0008] Laser scanning is performed according to the annealing scanning trajectory to complete annealing of the wafer.

[0009] Optionally, the light spot includes a rectangular light spot;

[0010] Forming the mth light spot in the (i+1)th light spot track to be tangent to the nth light spot in the (i)th light spot track includes:

[0011] The vertex of the mth rectangular light spot in the (i+1)th light spot track coincides with the vertex of the nth rectangular light spot in the ith light spot track.

[0012] Optionally, the light spot tracks are formed one by one along the y direction.

[0013] Optionally, the light spot tracks are formed one by one along the negative direction of the y direction.

[0014] Optionally, the center of the first light spot in the light spot trajectory is located on the y-axis, n=m+1.

[0015] Optionally, the center of the last light spot in the light spot track is located on the y-axis, and n=m.

[0016] Optionally, before forming the mth light spot in the (i+1)th light spot track and forming the nth light spot in the ith light spot track to be tangent to each other, the method further includes:

[0017] An initial light spot trajectory arc is formed.

[0018] Optionally, forming an initial light spot trajectory arc includes:

[0019] Determining the coordinate value of the center of the light spot in the initial light spot trajectory arc according to the radius of the initial light spot trajectory arc;

[0020] The initial light spot trajectory arc is formed according to the coordinate value of the center of the light spot in the initial light spot trajectory arc.

[0021] Optionally, the light spot in the initial light spot trajectory arc satisfies:

[0022]

[0023] R0 is the radius of the initial spot trajectory arc, x (1,j) is the x-coordinate value of the center of the j-th light spot in the arc of the initial light spot trajectory, and y (1,j) is the y-direction coordinate value of the center of the j-th light spot in the arc of the initial light spot trajectory, where j is a positive integer.

[0024] Optionally, in the process of forming the annealing scanning track, the process further includes:

[0025] Determining the coordinate value of the center of the light spot in the i-th light spot track according to the length of the light spot along the x-direction, the length of the light spot along the y-direction, the overlap rate along the y-direction, the displacement step length, and the radius of the wafer;

[0026] The i-th light spot track is formed according to the coordinate value of the center of the light spot in the i-th light spot track; wherein i is a positive integer greater than 1.

[0027] Optionally, the light spot in the i-th light spot trajectory satisfies:

[0028]

[0029] (x (i,j) +w) 2 +(y (i,j) -i×(1-Ove)×l) 2 =R 2 ;

[0030] x (i,j) is the x-direction coordinate value of the center of the j-th light spot in the i-th light spot trajectory, x (i,j+1) is the x-coordinate value of the center of the j+1th light spot in the i-th light spot trajectory, and y (i,j) is the y-coordinate value of the center of the j-th light spot in the i-th light spot trajectory, y (i,j+1) is the y-direction coordinate value of the center of the j+1th light spot in the i-th light spot trajectory, w is the length of the light spot along the x-direction, l is the length of the light spot along the y-direction, Ove is the overlap rate along the y-direction, δ l is the displacement step, R is the radius of the wafer, and j is a positive integer greater than 1.

[0031] Optionally, in the process of forming the annealing scanning track, the process further includes:

[0032] Obtaining the maximum surface temperature of the light spot along the x-direction according to the laser scanning speed in the x-direction;

[0033] According to the laser scanning speed in the y direction, the maximum surface temperature of the light spot along the y direction is obtained.

[0034] Optionally, the maximum surface temperature T of the light spot along the x direction x satisfy:

[0035]

[0036] The maximum surface temperature T of the light spot along the y direction y satisfy:

[0037]

[0038] Among them, V x is the laser scanning speed along the x direction, V y is the laser scanning speed along the y direction.

[0039] Optionally, performing laser scanning according to the annealing scanning trajectory to complete annealing of the wafer includes:

[0040] The laser is scanned along the annealing scanning track at a constant speed in the x direction to complete the annealing of the wafer.

[0041] Optionally, performing laser scanning according to the annealing scanning trajectory to complete annealing of the wafer includes:

[0042] The laser is scanned along the annealing scanning track at a constant linear speed to complete the annealing of the wafer.

[0043] Optionally, the wavelength of the laser is 10.6 μm.

[0044] In a second aspect, an embodiment of the present invention provides a laser annealing device, comprising:

[0045] Wafer stage, which carries the wafer;

[0046] A laser, emitting a laser beam, wherein the laser beam is projected onto the slide stage to form a light spot;

[0047] and a control system, wherein the control system executes the method according to the first aspect.

[0048] An embodiment of the present invention provides a laser annealing arc scanning method. In the process of forming an annealing scanning trajectory, the jth light spot in the (i+1)th light spot trajectory is tangent to the j+1th light spot in the (i)th light spot trajectory. The two light spots 211 tangent to the (i+1)th light spot trajectory and the (i)th light spot trajectory differ by the width of one light spot 211 along the x-direction, thereby controlling the degree of overlap between the mth light spot in the (i+1)th light spot trajectory and the mth light spot in the (i)th light spot trajectory, or controlling the degree of overlap between the m+1th light spot in the (i+1)th light spot trajectory and the nth light spot in the (i)th light spot trajectory. Therefore, the embodiment of the present invention completes multiple annealings in an area with insufficient annealing time through the planning of the light spot trajectory, thereby solving the problem of uniformity in the time dimension of arc scanning and improving the uniformity of wafer surface temperature. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1A flow chart of a laser annealing arc scanning method provided by an embodiment of the present invention;

[0050] Figure 2 A schematic diagram of an annealing scanning trajectory provided by an embodiment of the present invention;

[0051] Figure 3 for Figure 2 A schematic diagram of a partial spot trajectory in the annealing scanning trajectory shown in FIG;

[0052] Figure 4 for Figure 3 A tangent diagram of part of the light spot in the fourth quadrant;

[0053] Figure 5 for Figure 3 A tangent diagram of part of the light spot in the third quadrant;

[0054] Figure 6 A schematic diagram of another partial light spot trajectory provided by an embodiment of the present invention;

[0055] Figure 7 for Figure 6 A tangent diagram of part of the light spot in the first quadrant;

[0056] Figure 8 for Figure 6 A tangent diagram of part of the light spot in the second quadrant;

[0057] Figure 9 is a schematic diagram of linear velocity;

[0058] Figure 10 A schematic diagram of another annealing scanning trajectory provided by an embodiment of the present invention;

[0059] Figure 11 A schematic diagram of the maximum surface temperature of a light spot along the x-direction and the y-direction provided by an embodiment of the present invention;

[0060] Figure 12 The contour map of the maximum surface temperature inside the wafer when the wafer is annealed at a constant speed in the x-direction.

[0061] Figure 13 The contour map of the maximum surface temperature inside the wafer when the wafer is annealed at a constant line speed;

[0062] Figure 14 A schematic diagram of a laser annealing device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0063] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0064] Figure 1 A flowchart of a laser annealing arc scanning method provided by an embodiment of the present invention, Figure 2 A schematic diagram of an annealing scanning trajectory provided by an embodiment of the present invention, Figure 3 for Figure 2 A schematic diagram of a partial spot trajectory in the annealing scanning trajectory is shown in FIG. Figure 4 for Figure 3 A tangent diagram of part of the light spot in the fourth quadrant, refer to Figure 1-Figure 4 To clearly illustrate the overlap of the spots 211 of adjacent light spot tracks 21 along the y-direction, the spots 211 of adjacent light spot tracks 21 are filled in different ways. This embodiment can be used to perform arc scanning laser annealing on wafers such as silicon wafers. The method can be executed by a control system in a laser annealing device. The execution system can be implemented in software and / or hardware. The execution system can be, for example, a control device such as a computer or a single-chip microcomputer. The method includes:

[0065] S110: Provide a wafer.

[0066] In this step, the wafer 10 provided may be, for example, a silicon wafer. The process of providing the wafer 10 may include, for example, a wafer loading process.

[0067] S120. Form an annealing scanning trajectory; wherein the annealing scanning trajectory includes a plurality of arc-shaped light spot trajectories arranged along the y direction, and each light spot trajectory includes a plurality of light spots arranged along the x direction, so that the mth light spot in the (i+1)th light spot trajectory is tangent to the nth light spot in the (i)th light spot trajectory, and i, m, and n are all positive integers; along the x direction, the distance between the mth light spot in the (i+1)th light spot trajectory and the nth light spot in the (i)th light spot trajectory is equal to the length of the light spot along the x direction.

[0068] In this step, an annealing scanning track 20 is formed, and the annealing scanning track 20 includes a plurality of light spot tracks 21. The plurality of light spot tracks 21 extend along the x direction and are arranged along the y direction. Figure 2As shown, two adjacent spot tracks 21 have opposite scanning directions. Therefore, after completing a laser scan along one spot track 21, the end position of the current spot track 21 can be used as the starting scanning position of the next spot track 21 to start the next laser scan. In one embodiment, the laser scan can be performed on the wafer 10 along the y direction. In another embodiment, the laser scan can also be performed along the negative y direction.

[0069] like Figure 3 As shown, each light spot track 21 includes a plurality of light spots 211 arranged along the x direction. For clarity, please see, Figure 3 In the figure, the arc formed by connecting the centers of multiple light spots 211 (i.e., the light spot centers) represents the light spot track 21, and the i-th light spot track, the i+1-th light spot track, and the i+2-th light spot track are exemplarily illustrated. In fact, the light spot track 21 is a light band formed by the continuous movement of the light spot 211.

[0070] Since arc scanning has a time dimension uniformity problem, the time dimension uniformity problem is mainly due to the fact that arc scanning cannot guarantee the consistency of the laser dwell time at any point, which leads to insufficient annealing time in some areas and poor temperature uniformity on the wafer surface. In this embodiment, in the process of forming the annealing scanning track 20, the mth light spot in the i+1th light spot track is tangent to the nth light spot in the i-th light spot track. The two light spots 211 that are tangent to the i+1th light spot track and the i-th light spot track differ in the x-direction by the width of the light spot 211, and the width of the light spot 211 is the length of the light spot 211 along the x-direction. Therefore, through the planning of the light spot track 21, multiple annealing is completed in the area with insufficient annealing time, thereby improving the uniformity of the wafer surface temperature.

[0071] S130 , performing laser scanning according to the annealing scanning trajectory to complete annealing of the wafer.

[0072] Based on the annealing scanning track 20 having been formed in the above steps, in this step, laser scanning can be performed along the annealing scanning track 20 to complete the annealing of the wafer 10 .

[0073] An embodiment of the present invention provides a laser annealing arc scanning method. In the process of forming an annealing scanning track 20, the mth light spot in the i+1th light spot track is tangent to the nth light spot in the i-th light spot track. The two light spots 211 tangent to the i+1th light spot track and the i-th light spot track differ by the width of one light spot 211 along the x-direction, thereby controlling the degree of overlap between the mth light spot in the i+1th light spot track and the mth light spot in the i-th light spot track, or controlling the degree of overlap between the m+1th light spot in the i+1th light spot track and the nth light spot in the i-th light spot track. Therefore, the embodiment of the present invention completes multiple annealings in the area with insufficient annealing time through the planning of the light spot track 21, solves the problem of uniformity in the time dimension of arc scanning, and improves the uniformity of wafer surface temperature.

[0074] Optionally, refer to Figure 3 and Figure 4 , the light spot 211 includes a rectangular light spot. The above step 120 may include: forming the vertex of the mth rectangular light spot in the (i+1)th light spot track 21 to coincide with the vertex of the nth rectangular light spot in the (i)th light spot track 21. In the embodiment of the present invention, the light spot 211 includes a rectangular light spot, so that the vertices of the two tangent light spots 211 in the (i+1)th light spot track and the (i)th light spot track coincide. In other embodiments, the light spot 211 may also have other shapes, such as circular, elliptical, hexagonal, octagonal, etc., which are not limited in the embodiment of the present invention.

[0075] Optionally, refer to Figure 3 and Figure 4 , along the y direction, each light spot track 21 is formed one by one. That is, along the y direction (i.e., the positive direction of the y axis), the i-th light spot track is formed first, then the i+1-th light spot track is formed, and then the i+2-th light spot track is formed, and so on. For example, referring to Figure 3 and Figure 4 The light spot 211 includes a rectangular light spot, so that when the light spot track 21 is sequentially formed along the y direction, the upper vertex on one side of any rectangular light spot in a light spot track 21 coincides with the lower vertex on the other side of the rectangular light spot corresponding to the next light spot track 21.

[0076] For example, refer to Figure 3 In the third quadrant, the upper right corner of any rectangular light spot in a light spot track 21 coincides with the lower left corner of the rectangular light spot corresponding to the next light spot track 21. In the fourth quadrant, the upper left corner of any rectangular light spot in a light spot track 21 coincides with the lower right corner of the rectangular light spot corresponding to the next light spot track 21. Figure 4As shown, in the fourth quadrant, the lower right corner of the light spot 321 coincides with the upper left corner of the light spot 312. The (i+1)th light spot track 21 is the "next light spot track 21" of the (i)th light spot track 21, and i is a positive integer.

[0077] Optionally, refer to Figure 3 and Figure 4 , the center of the first light spot 211 of the light spot track 21 is located on the y-axis, n=m+1. In the embodiment of the present invention, each light spot track 21 is formed one by one along the y-direction. And the starting point for generating each light spot track 21 is located on the y-axis, and each light spot 211 in the light spot track 21 is generated in a direction away from the y-axis, that is, each light spot 211 in the light spot track 21 is generated from the center to the periphery. Among them, the starting point for generating the light spot track 21 is the design starting point when generating the light spot track 21, and is not the actual scanning starting point of the light spot track 21 during the annealing process of the wafer 10.

[0078] For example, refer to Figure 3 and Figure 4 , taking m=1, n=2 as an example. The first light spot in the i-th light spot trajectory 21 is recorded as light spot 311, and the second light spot in the i-th light spot trajectory 21 is recorded as light spot 312. The first light spot in the i+1-th light spot trajectory 21 is recorded as light spot 321. The light spot centers of light spot 311 and light spot 321 are both located on the y-axis. The first light spot in the i+1-th light spot trajectory is tangent to the second light spot in the i-th light spot trajectory, that is, light spot 321 is tangent to light spot 312, and the tangent light spots 321 and 312 have only one overlapping point. When light spots 321 and 312 are tangent, light spots 311 and 321 partially overlap along the y-direction.

[0079] Illustratively, the light spots 321 in the first and fourth quadrants may be generated first, and then the light spots 321 in the second and third quadrants may be generated by y-axis mirroring to form multiple light spot tracks 21 and finally form the annealing scanning track 20 .

[0080] Figure 5 for Figure 3 A tangent diagram of part of the light spot in the third quadrant, combined with Figure 3 and Figure 5, along the y direction, each light spot track 21 is formed one by one. The center of the last light spot 211 of the light spot track 21 is located on the y-axis, n=m. In the embodiment of the present invention, each light spot track 21 is formed one by one along the y-direction. And the generation end point of each light spot track 21 is located on the y-axis, and each light spot 211 in the light spot track 21 is generated in the direction toward the y-axis, that is, each light spot 211 in the light spot track 21 is generated from the periphery to the center. Among them, the generation end point of the light spot track 21 is the design end point when the light spot track 21 is generated, and is not the actual scanning end point of the light spot track 21 during the annealing process of the wafer 10.

[0081] For example, refer to Figure 3 and Figure 5 , taking m=1, n=1 as an example. The first light spot in the i-th light spot trajectory 21 is recorded as light spot 311, and the second light spot in the i-th light spot trajectory 21 is recorded as light spot 312. The first light spot in the i+1-th light spot trajectory 21 is recorded as light spot 321. The light spot centers of light spot 311 and light spot 321 are both located in the third quadrant. The first light spot in the i+1-th light spot trajectory is tangent to the first light spot in the i-th light spot trajectory, that is, light spot 321 is tangent to light spot 311, and the tangent light spots 321 and 311 have only one overlapping point. When light spots 321 are tangent to light spots 311, light spots 321 and 312 partially overlap along the y direction.

[0082] Figure 6 A schematic diagram of another partial light spot trajectory provided by an embodiment of the present invention, referring to Figure 6 , along the negative direction of the y-axis, each light spot track 21 is formed one by one. That is, along the negative direction of the y-axis, the i-th light spot track is formed first, then the i+1-th light spot track is formed, and then the i+2-th light spot track is formed, and so on.

[0083] Figure 7 for Figure 6 A tangent diagram of part of the light spot in the first quadrant, refer to Figure 6 and Figure 7 , the light spot 211 includes a rectangular light spot, so that when the light spot tracks 21 are sequentially formed along the negative direction of the y direction, the lower vertex on one side of any rectangular light spot in a light spot track 21 coincides with the upper vertex on the other side of the rectangular light spot corresponding to the next light spot track 21.

[0084] Optionally, refer to Figure 6 and Figure 7The center of the first light spot 21 of the light spot track 21 is located on the y-axis, and m=n+1. In the embodiment of the present invention, each light spot track 21 is formed one by one along the negative direction of the y-direction. The starting point of each light spot track 21 is located on the y-axis, and each light spot 211 in the light spot track 21 is generated in a direction away from the y-axis, that is, each light spot 211 in the light spot track 21 is generated from the center to the periphery.

[0085] For example, refer to Figure 6 and Figure 7 , taking m = 1 and n = 2 as an example. The first light spot in the i-th light spot track 21 is denoted as light spot 311, and the second light spot in the i-th light spot track 21 is denoted as light spot 312. The first light spot in the i+1-th light spot track 21 is denoted as light spot 321. The light spot centers of light spots 311 and 321 are both located on the y-axis. The first light spot in the i+1-th light spot track is tangent to the second light spot in the i-th light spot track.

[0086] Figure 8 for Figure 6 A tangent diagram of part of the light spot in the second quadrant, refer to Figure 6 and Figure 8 , each light spot track 21 is formed one by one along the negative direction of the y-direction. The center of the last light spot 211 of the light spot track 21 is located on the y-axis, where n = m. In this embodiment of the present invention, each light spot track 21 is formed one by one along the negative direction of the y-direction. The generation end point of each light spot track 21 is located on the y-axis, and each light spot 211 in the light spot track 21 is generated in the direction toward the y-axis, that is, from the periphery to the center.

[0087] For example, refer to Figure 6 and Figure 8, taking m=1, n=1 as an example. The first light spot in the i-th light spot trajectory 21 is recorded as light spot 311, and the second light spot in the i-th light spot trajectory 21 is recorded as light spot 312. The first light spot in the i+1-th light spot trajectory 21 is recorded as light spot 321. The spot centers of light spot 311 and light spot 321 are both located in the second quadrant. The first light spot in the i+1-th light spot trajectory is formed tangent to the first light spot in the i-th light spot trajectory. Optionally, in the process of forming the annealing scanning trajectory 20, before the j-th light spot in the i+1-th light spot trajectory is formed tangent to the j+1-th light spot in the i-th light spot trajectory, the laser annealing arc scanning method may further include: forming an initial light spot trajectory arc. The initial light spot trajectory arc is formed, that is, the first light spot trajectory 21 is formed, and the first light spot trajectory 21 is an arc. In the embodiment of the present invention, an initial light spot track arc is first formed, and based on the initial light spot track arc, subsequent second light spot track 21 , third light spot track 21 , . . . are sequentially formed until all the light spot tracks 21 are formed.

[0088] Optionally, the step of forming an initial light spot trajectory arc includes:

[0089] The first step is to determine the coordinate value of the center of the light spot in the initial light spot trajectory arc according to the radius of the initial light spot trajectory arc.

[0090] In the second step, an initial light spot trajectory arc is formed according to the coordinate value of the center of the light spot in the initial light spot trajectory arc.

[0091] Furthermore, the light spot 211 in the initial light spot trajectory arc satisfies the following formula:

[0092]

[0093] Among them, R0 is the radius of the initial spot trajectory arc, x (1,j) is the x-coordinate value of the center of the j-th light spot 211 in the initial light spot trajectory arc, and y (1,j) is the y-direction coordinate value of the center of the j-th light spot 211 in the initial light spot trajectory arc, where j is a positive integer.

[0094] Optionally, in the process of forming the annealing scanning track, the process further includes:

[0095] The first step is to determine the coordinate value of the center of the light spot in the i-th light spot track based on the length of the light spot along the x-direction, the length of the light spot along the y-direction, the overlap rate along the y-direction, the displacement step size, and the radius of the wafer. Where i is a positive integer greater than 1.

[0096] In the second step, the ith light spot track is formed according to the coordinate value of the center of the light spot in the ith light spot track.

[0097] Furthermore, taking the initial light spot track arc as a reference, subsequent light spot tracks 21 are formed in sequence, and the light spot in the i-th light spot track satisfies the following formula:

[0098]

[0099] (x (i,j) +w) 2 +(y (i,j) -i×(1-Ove)×l) 2 =R 2 (3)

[0100] Among them, x (i,j) is the x-direction coordinate value of the center of the j-th light spot in the i-th light spot trajectory 21, x (i,j+1) is the x-coordinate value of the center of the j+1th light spot 211 in the i-th light spot track 21, and y (i,j) is the y-direction coordinate value of the center of the j-th light spot 211 in the i-th light spot track 21, y (i,j+1) is the y-direction coordinate value of the center of the j+1th light spot 211 in the i-th light spot trajectory 21, w is the length of the light spot 21 along the x-direction, l is the length of the light spot 21 along the y-direction, Ove is the overlap rate along the y-direction, δ l is the displacement step length, R is the radius of the wafer 10, i is a positive integer greater than 1, that is, i=2, 3, 4, ..., and j is a positive integer.

[0101] The overlap ratio Ove along the y direction satisfies: 0≤Ove<1.

[0102] Optionally, the displacement step δ l Satisfies the following formula:

[0103] δ l =V l ×δ t (4)

[0104] Among them, V l is the linear velocity of laser scanning, δ t is the time step.

[0105] Figure 9 Schematic diagram of linear velocity, the linear velocity V of laser scanning l The component in the x direction is V x , the linear velocity of the laser scan is V l The component in the y direction is V y That is, V x is the laser scanning speed along the x direction, V y is the laser scanning speed along the y direction.

[0106] Figure 10A schematic diagram of another annealing scanning trajectory provided by an embodiment of the present invention, referring to Figure 10 An annealing scanning track is formed according to the laser annealing arc scanning method in the above embodiment, and laser scanning is performed along the annealing scanning track to complete the annealing of the wafer 10 .

[0107] Optionally, in the process of forming the annealing scanning track, the process further includes:

[0108] In the first step, the maximum surface temperature of the light spot along the x direction is obtained according to the laser scanning speed in the x direction.

[0109] In the second step, the maximum surface temperature of the light spot along the y direction is obtained according to the laser scanning speed in the y direction.

[0110] Figure 11 A schematic diagram of the maximum surface temperature of a light spot along the x-direction and the y-direction provided by an embodiment of the present invention, with reference to Figure 11 , further, the maximum surface temperature T of the light spot 211 along the x direction x Satisfies the following formula:

[0111]

[0112] The maximum surface temperature T of the light spot 211 along the y direction y Satisfies the following formula:

[0113]

[0114] Among them, V x is the laser scanning speed along the x direction, V y is the laser scanning speed along the y direction. Figure 11 The scanning speed in the x direction is the laser scanning speed. x and the scanning speed V in the y direction y The unit is mm / s, and the scanning speed is greater than or equal to 20 mm / s and less than or equal to 400 mm / s.

[0115] The issue of temporal uniformity is primarily due to the fact that arc scanning cannot guarantee consistent laser dwell time at any point. This is reflected in the significant differences in the dwell time of spot 211 at different upper and lower positions along the y-direction. This embodiment of the present invention, using consistent x-direction velocity and linear velocity as an example, further reduces temporal uniformity by balancing the contributions of x- and y-direction velocities to the annealing temperature.

[0116] Optionally, in one embodiment, the above step 130 may include: performing laser scanning along the annealing scanning trajectory at a constant x-direction speed to complete the annealing of the wafer 10. In other words, the laser scanning speed in the x-direction is constant. The laser scanning speed V in the x-direction is x satisfy:

[0117]

[0118] Wherein, w is the length of the light spot 21 along the x direction, Dwe x In the embodiment of the present invention, the speed of the laser scanning in the x direction is controlled to be constant, so that the dwell time at each position (denoted as Dwe in the embodiment of the present invention) is constant. x ) are the same, further reducing the uniformity difference in the time dimension.

[0119] Alternatively, in another embodiment, the above step 130 may include: performing laser scanning along the annealing scanning trajectory at a constant linear velocity to complete the annealing of the wafer 10. In other words, the laser scanning has a constant speed in its actual motion direction. l satisfy:

[0120]

[0121] Wherein, w is the length of the light spot 21 along the x direction, Dwe l In the embodiment of the present invention, the linear velocity of the laser scanning is controlled to be constant, so that the dwell time at each position (denoted as Dwe in the embodiment of the present invention) is constant. l ) are the same, further reducing the uniformity difference in the time dimension. It should be noted that the dwell time is a parameter during laser scanning and can have different values ​​under different scanning modes.

[0122] Figure 12 The contour map of the highest surface temperature inside the wafer when the wafer is annealed at a constant speed in the x direction is shown in the figure. Figure 13 For the contour map of the highest surface temperature in the wafer when the wafer is annealed at a constant line speed, refer to Figure 12 and Figure 13 When the laser scans along the annealing scan trajectory at a constant x-direction speed, the inter-chip temperature difference is 53°C. When the laser scans along the annealing scan trajectory at a constant linear velocity, the inter-chip temperature difference is 41°C. The constant linear velocity approach offers the advantage of better temporal uniformity.

[0123] On the basis of the above embodiments, further, the temperature difference can be controlled within the temperature uniformity range required by the process through an annealing temperature closed-loop control system.

[0124] Optionally, the wavelength of the laser is 10.6 μm.

[0125] Exemplarily, the length of the light spot 211 along the y direction is 11 mm, the length of the light spot 211 along the x direction is 0.08 mm, and the dwell time is 1 ms.

[0126] Illustratively, after the above step S110 and before the above step S120 , the laser annealing arc scanning method may further include: performing pre-treatment on the wafer 10 before annealing.

[0127] Figure 14 A schematic diagram of a laser annealing device provided in an embodiment of the present invention, referring to Figure 14 The laser annealing device includes a wafer stage 30, a laser 40 and a control system 50. The wafer stage 30 carries the wafer 10. The laser 40 emits a laser beam, and the laser beam is projected onto the wafer stage 30 to form a light spot 211. It can be understood that when the wafer 10 is carried on the wafer stage 30, the laser beam can also form a light spot 211 when it is projected onto the wafer 10 carried by the wafer stage 30. The control system 50 executes the above-mentioned laser annealing arc scanning method. Since the laser annealing device provided by an embodiment of the present invention includes a control system 50 that executes the above-mentioned laser annealing arc scanning method, the laser annealing device provided by an embodiment of the present invention can complete multiple annealing in the area with insufficient annealing time through the planning of the light spot trajectory, thereby improving the uniformity of the wafer surface temperature.

[0128] For example, refer to Figure 14 The wafer stage 30 and the laser 40 are both connected to a control system 50, which can control the beam angle, laser intensity, and scanning path of the laser 40. The control system 50 can also control the motion path of the wafer stage 30, thereby controlling the wafer stage 30 to move the wafer 10 to a predetermined position.

[0129] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations, and substitutions are possible for those skilled in the art without departing from the scope of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the scope of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A laser annealing arc scanning method, characterized in that: include: Provide wafers; forming an annealing scanning track; wherein the annealing scanning track includes a plurality of arc-shaped light spot tracks arranged along the y direction, each of the light spot tracks includes a plurality of light spots arranged along the x direction, the mth light spot in the (i+1)th light spot track is tangent to the nth light spot in the (i)th light spot track, and i, m, and n are all positive integers; along the x direction, the distance between the mth light spot in the (i+1)th light spot track and the nth light spot in the (i)th light spot track is equal to the length of the light spot along the x direction; Performing laser scanning along the annealing scanning trajectory to complete annealing of the wafer; The light spot includes a rectangular light spot; The method of forming the mth light spot in the (i+1)th light spot track to be tangent to the nth light spot in the i-th light spot track comprises: The vertex of the mth rectangular light spot in the (i+1)th light spot track coincides with the vertex of the nth rectangular light spot in the ith light spot track.

2. The method according to claim 1, characterized in that Along the y direction, the light spot tracks are formed one by one.

3. The method according to claim 1, characterized in that Along the negative direction of the y direction, the light spot tracks are formed one by one.

4. The method according to claim 2 or 3, characterized in that The center of the first light spot in the light spot track is located on the y-axis, n=m+1.

5. The method according to claim 2 or 3, characterized in that: The center of the last light spot of the light spot track is located on the y-axis, n=m.

6. The method according to claim 1, wherein Before forming the mth light spot in the (i+1)th light spot track to be tangent to the nth light spot in the ith light spot track, the method further includes: An initial light spot trajectory arc is formed.

7. The method according to claim 6, characterized in that The initial spot trajectory arc is formed, including: Determining the coordinate value of the center of the light spot in the initial light spot trajectory arc according to the radius of the initial light spot trajectory arc; The initial light spot trajectory arc is formed according to the coordinate value of the center of the light spot in the initial light spot trajectory arc.

8. The method according to claim 7, characterized in that The light spot in the arc of the initial light spot trajectory satisfies: R0 is the radius of the initial spot trajectory arc, x (1,j) is the x-coordinate value of the center of the j-th light spot in the arc of the initial light spot trajectory, and y (1,j) is the y-direction coordinate value of the center of the j-th light spot in the arc of the initial light spot trajectory, where j is a positive integer.

9. The method according to claim 1, characterized in that The process of forming the annealing scanning track also includes: Determining the coordinate value of the center of the light spot in the i-th light spot track according to the length of the light spot along the x-direction, the length of the light spot along the y-direction, the overlap rate along the y-direction, the displacement step length, and the radius of the wafer; The i-th light spot track is formed according to the coordinate value of the center of the light spot in the i-th light spot track; wherein i is a positive integer greater than 1.

10. The method according to claim 9, characterized in that The light spot in the i-th light spot trajectory satisfies: (x (i,j) +w) 2 +(y (i,j) -i×(1-Ove)×l) 2 =R 2 ; x (i,j) is the x-direction coordinate value of the center of the j-th light spot in the i-th light spot trajectory, x (i,j+1) is the x-coordinate value of the center of the j+1th light spot in the i-th light spot trajectory, and y (i,j) is the y-direction coordinate value of the center of the j-th light spot in the i-th light spot trajectory, y (i,j+1) is the y-direction coordinate value of the center of the j+1th light spot in the i-th light spot trajectory, w is the length of the light spot along the x-direction, l is the length of the light spot along the y-direction, Ove is the overlap rate along the y-direction, δ l is the displacement step, R is the radius of the wafer, and j is a positive integer greater than 1.

11. The method according to claim 1, wherein The process of forming the annealing scanning track also includes: Obtaining the maximum surface temperature of the light spot along the x-direction according to the laser scanning speed in the x-direction; According to the laser scanning speed in the y direction, the maximum surface temperature of the light spot along the y direction is obtained.

12. The method according to claim 10, characterized in that The maximum surface temperature T of the light spot along the x direction x satisfy: The maximum surface temperature T of the light spot along the y direction y satisfy: Among them, V x is the laser scanning speed along the x direction, V y is the laser scanning speed along the y direction.

13. The method according to claim 1, wherein Performing laser scanning according to the annealing scanning trajectory to complete annealing of the wafer includes: The laser is scanned along the annealing scanning track at a constant speed in the x direction to complete the annealing of the wafer.

14. The method according to claim 1, wherein Performing laser scanning according to the annealing scanning trajectory to complete annealing of the wafer includes: The laser is scanned at a constant linear speed along the annealing scanning track to complete the annealing of the wafer.

15. The method according to claim 1, wherein The wavelength of the laser is 10.6 μm.

16. A laser annealing device, characterized in that: include: Wafer stage, which carries the wafer; A laser, emitting a laser beam, wherein the laser beam is projected onto the slide stage to form a light spot; and a control system, wherein the control system executes the method according to any one of claims 1 to 15.

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