Laser annealing scanning method and device

Abstract

The invention relates to the technical field of laser heat treatment, in particular to a laser annealing scanning method and device. The laser annealing scanning method comprises the following steps: determining a scanning track, controlling a light spot to scan an edge protection area on the surface of a wafer along a first low-power section at first power, controlling the light spot to scan the edge protection area on the surface of the wafer along a power rising section, and controlling the light spot to scan the surface of the wafer along a high-power section at second power, and controlling the light spot to scan the edge protection area on the surface of the wafer along the power drop section, controlling the light spot to scan the edge protection area on the surface of the wafer along the second low power section at the third power, and realizing protection on the edge of the wafer by controlling the power of each scanning section of the scanning track.

Description

Technical Field

[0001] The present invention relates to the technical field of laser heat treatment, and in particular to a laser annealing scanning method and device. Background Art

[0002] Laser heat treatment, also commonly known as rapid thermal processing, has important applications in the semiconductor device manufacturing industry. Laser heat treatment technology uses a localized strong radiation beam to irradiate the wafer surface, quickly heating the wafer surface from a lower temperature (such as 400°C) to a relatively high temperature (such as 1300°C), and the body part other than the wafer surface can quickly reduce the temperature. The key to this technology is the need for ultra-high temperature and ultra-short annealing time, which can reduce the diffusion of dopants and retain the abrupt step-shaped dopant distribution after the implantation step.

[0003] The wafer is a silicon wafer with doped source and drain regions. Usually, the wafer that is processed to be annealed contains many complex structures inside, and these structures may overlap. Annealing requires the wafer to be heated and activated during the formation of transistors. As the feature size of transistors continues to shrink, a laser spike annealing process has been developed. This process uses a CO2 laser beam to irradiate the surface of the wafer to form a scanned image along the surface of the wafer. In a typical scanning path configuration, a beam with a width of 0.1 mm scans the surface of the wafer in a straight line at a speed of 100 mm / s, resulting in a dwell time of 1 ms. For an 800 μm thick wafer, only about 100-200 μm thick material on the surface of the wafer needs to be raised to the annealing temperature, and most of the role of the wafer body is to cool the irradiated wafer surface. However, during the production process of the existing process, semiconductor wafers are susceptible to ultra-high temperatures during laser annealing, resulting in wafer edge damage. Summary of the invention

[0004] The object of the present invention is to provide a laser annealing scanning method and device to solve the problem of wafer edge damage due to ultra-high temperature.

[0005] An embodiment of the present invention provides a laser annealing scanning method, the scanning method comprising the following steps:

[0006] Determine a scanning trajectory, wherein the scanning trajectory is an arc-shaped structure with an opening facing away from the incident direction of the laser spot, and includes a first low-power section, a power increase section, a high-power section, a power decrease section, and a second low-power section connected in sequence from one end to the other end;

[0007] Controlling the light spot to scan the edge protection zone of the wafer surface along the first low-power section at the first power, and the light spot at the end position of the first low-power section just completely enters the edge protection zone of the wafer surface, and the edge protection zone is a circular ring area radially inward from the outer edge of the wafer;

[0008] Controlling the light spot to scan the edge protection area of ​​the wafer surface along the power rising section, wherein the scanning power of the light spot gradually increases from the first power to the second power, and the light spot at the end position of the power rising section is located in the edge protection area;

[0009] Controlling the light spot to scan the wafer surface along the high power section at the second power, the light spot at the head end position of the high power section begins to leave the edge protection area and enter the central scanning area, and the light spot at the end position of the high power section has left the central scanning area and entered the edge protection area;

[0010] Controlling the light spot to scan the edge protection area of ​​the wafer surface along the power decreasing section, wherein the scanning power of the light spot gradually decreases from the second power to a third power, and the light spot at the head end of the power decreasing section is located in the edge protection area;

[0011] The light spot is controlled to scan the edge protection area of ​​the wafer surface along the second low-power section at the third power, and the light spot at the end position of the second low-power section completely leaves the wafer surface.

[0012] Optionally, the power rising section includes a first power rising section, a first power constant section, and a second power rising section which are connected end to end in sequence, the head end of the first power rising section is connected to the end of the first low power section, and the end of the second power rising section is connected to the head end of the high power section; controlling the light spot to scan the edge protection area of ​​the wafer surface along the power rising section includes the following steps:

[0013] Controlling the light spot to scan the edge protection area of ​​the wafer surface along the first power rising section, wherein the scanning power of the light spot gradually increases from the first power to the fourth power;

[0014] Controlling the light spot to scan the edge protection zone of the wafer surface along the first constant power section at the fourth power;

[0015] The light spot is controlled to scan the wafer surface along the second power rising section, wherein the scanning power of the light spot gradually increases from the fourth power to the edge protection area of ​​the second power.

[0016] Optionally, the power reduction section includes a first power reduction section, a second constant power section, and a second power reduction section which are connected end to end in sequence, the head end of the first power reduction section is connected to the end of the high power section, and the end of the second power reduction section is connected to the head end of the second low power section; controlling the light spot to scan the edge protection area of ​​the wafer surface along the power reduction section includes the following steps:

[0017] Controlling the light spot to scan the edge protection area of ​​the wafer surface along the first power decreasing section, wherein the scanning power of the light spot gradually decreases from the second power to the fourth power;

[0018] Controlling the light spot to scan the edge protection zone of the wafer surface along the second constant power section at the fourth power;

[0019] The light spot is controlled to scan the edge protection area of ​​the wafer surface along the second power decreasing section, wherein the scanning power of the light spot gradually decreases from the fourth power to the third power, and the third power is equal to the first power.

[0020] Optionally, the scanning method further comprises the following steps:

[0021] Acquiring the width of the light spot and the dwell time of the light spot;

[0022] A preset speed of the light spot along a first direction is determined according to the width and the dwell time.

[0023] Optionally, the scanning trajectory further includes an acceleration section, the end of the acceleration section is connected to the beginning of the first low-power section, and the acceleration section is located outside the wafer surface; before the step of controlling the light spot to scan the edge protection area of ​​the wafer surface along the first low-power section at the first power, the following steps are also included:

[0024] The light spot is controlled to accelerate at a first power in the acceleration section, and is accelerated to the preset speed at the end of the acceleration section.

[0025] Optionally, the scanning trajectory further includes a speed reduction segment, the head end of the speed reduction segment is connected to the end of the second low-power segment, and the speed reduction segment is located outside the wafer surface; after the step of controlling the light spot to scan the edge protection area of ​​the wafer surface along the power reduction segment, the following steps are also included:

[0026] Controlling the light spot to decelerate along the deceleration section at a third power and decelerate to zero at the end of the deceleration section, wherein the third power is equal to the first power;

[0027] The light spot is controlled to move along a second direction by half the length of the light spot, wherein the second direction is parallel to the wafer surface and perpendicular to the first direction.

[0028] Optionally, the scanning trajectory includes a first straight line segment, a circular arc segment, and a second straight line segment connected end to end in sequence, the first straight line segment is tangent to the circular arc segment at a first tangent point, and the second straight line segment is tangent to the circular arc segment at a second tangent point; the determining the scanning trajectory includes the following steps:

[0029] Determine the radius of the arc segment: R = 1 / 2 (DL-2EPA);

[0030] Determine an angle between the first tangent point and a central axis of the wafer surface, wherein the angle is between a first angle and a second angle;

[0031] Determine the first tangent point position according to the arc segment radius and the included angle;

[0032] Determine the position of the second tangent point according to the symmetry between the second tangent point and the first tangent point about the central axis;

[0033] Determine the first straight line segment, the second straight line segment and the arc segment trajectory according to the first tangent point position, the second tangent point position and the arc radius;

[0034] Among them, R is the arc radius; D is the wafer diameter; L is the spot length; EPA is the radial distance of the edge protection area; the first angle is the minimum angle that meets the preset annealing requirements, and the second angle is the maximum angle limited by the maximum moving speed of the spot scanning in the second direction.

[0035] Optionally, the scanning method further comprises the following steps:

[0036] The light spot is controlled to perform reverse scanning along the scanning track.

[0037] Compared with the prior art, the laser annealing scanning method provided by the present invention has the following beneficial effects:

[0038] The laser annealing scanning method provided by the embodiment of the present invention determines a scanning trajectory, which is an arc-shaped structure with an opening facing away from the incident direction of the laser spot, and includes a first low-power section, a power rising section, a high-power section, a power falling section and a second low-power section connected in sequence from one end to the other end; the light spot is controlled to scan the edge protection area of ​​the wafer surface along the first low-power section with a first power to protect the wafer edge; the light spot is controlled to scan the edge protection area of ​​the wafer surface along the power rising section to achieve power rising, avoid damage to the wafer edge caused by too fast power change, and prepare for subsequent light spot scanning of the high-power section; the light spot is controlled to scan the wafer surface along the high-power section with a second power to achieve scanning the high-power section; the light spot is controlled to scan the edge protection area of ​​the wafer surface along the power falling section to achieve power falling, avoid damage to the wafer edge caused by too fast power change, and prepare for subsequent scanning of the second low-power section; the light spot is controlled to scan the edge protection area of ​​the wafer surface along the second low-power section with a third power to protect the wafer edge; in summary, the method provided by the embodiment of the present invention realizes protection of the wafer edge by controlling the power of each scanning section of the scanning trajectory.

[0039] The present invention provides a laser annealing scanning device for implementing the above-mentioned scanning method, the scanning device comprising:

[0040] A determination module, used for determining a scanning trajectory;

[0041] A control module is used to control the light spot to scan the edge protection zone of the wafer surface along the first low power section at the first power, control the light spot to scan the edge protection zone of the wafer surface along the power rising section, control the light spot to scan the edge protection zone of the wafer surface along the second high power section, control the light spot to scan the edge protection zone of the wafer surface along the power falling section, and control the light spot to scan the edge protection zone of the wafer surface along the second low power section at the third power.

[0042] Optionally, the control module includes:

[0043] The PC side is used to generate a first control command and a second control command;

[0044] A PXI system, used for receiving the first control command and controlling the laser power;

[0045] The controller is used to receive the second control command and control the motion platform.

[0046] The laser annealing scanning device provided by the present invention has the beneficial effect of being able to achieve the same technical effect as the above-mentioned laser annealing scanning method, and will not be described again here to avoid repetition. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0048] Figure 1 A schematic flow chart of a laser annealing scanning method provided in an embodiment of the present invention;

[0049] Figure 2 This is a schematic structural diagram of a laser annealing scanning device according to an embodiment of the present invention;

[0050] Figure 3 A schematic top view of a wafer scanning trajectory in an embodiment of the present invention;

[0051] Figure 4 Schematic diagram of PID regulation overshoot phenomenon in an embodiment of the present invention;

[0052] Figure 5Schematic diagram of the change of the light spot scanning speed in an embodiment of the present invention;

[0053] Figure 6 This is a schematic diagram of an annealing area after a single annealing process in an embodiment of the present invention;

[0054] Figure 7 A schematic diagram of an annealing area after a reverse scanning secondary annealing process in an embodiment of the present invention;

[0055] Figure 8 A schematic top view of another wafer scanning trajectory in an embodiment of the present invention;

[0056] Fig. 9 A schematic diagram of partition scanning in an embodiment of the present invention;

[0057] Fig.10 Schematic diagram of the effects of annealing processes at different polar angles in an embodiment of the present invention;

[0058] Fig.11 Schematic diagram of the relationship between speed and polar angle in an embodiment of the present invention;

[0059] Fig.12 Schematic diagram of the specific structure of the laser annealing scanning device in an embodiment of the present invention. DETAILED DESCRIPTION

[0060] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0061] The embodiment of the present invention provides a laser annealing scanning method, taking a laser annealing system applied to a wafer as an example, Figure 1 As shown, the scanning method includes the following steps:

[0062] S110, determining a scanning trajectory, wherein the scanning trajectory is an arc-shaped structure with an opening facing away from the incident direction of the laser spot, and includes a first low-power segment, a power increase segment, a high-power segment, a power decrease segment, and a second low-power segment connected in sequence from one end to the other end;

[0063] S120, controlling the light spot to scan the edge protection zone of the wafer surface along the first low-power section at the first power, and the light spot at the end position of the first low-power section just completely enters the edge protection zone of the wafer surface, and the edge protection zone is a circular ring area radially inward from the outer edge of the wafer;

[0064] It should be noted that the edge protection area on the wafer surface is an area to prevent the wafer edge from cracking.

[0065] S130, controlling the light spot to scan the edge protection zone of the wafer surface along the power rising section, wherein the scanning power of the light spot gradually rises from the first power to the second power, and the light spot at the end position of the power rising section is located in the edge protection zone;

[0066] S140, controlling the light spot to scan the wafer surface along the high power section at the second power, the light spot at the head end of the high power section begins to leave the edge protection area and enter the central scanning area, and the light spot at the end of the high power section has left the central scanning area and entered the edge protection area;

[0067] It should be noted that the light spot irradiates the central scanning area of ​​the wafer surface with the second power for annealing process. The area irradiated by the light spot must always maintain an ultra-high temperature (1200°C), which requires a laser output power of approximately 2400W. The most critical thing is to stabilize the temperature state through closed-loop control, and the temperature difference must be less than ±10°C.

[0068] S150, controlling the light spot to scan the edge protection zone of the wafer surface along the power reduction section, wherein the scanning power of the light spot gradually decreases from the second power to the third power, and the light spot at the beginning of the power reduction section is located in the edge protection zone.

[0069] Alternatively, a CO2 laser may be selected as the laser light source.

[0070] It should be noted that the normal line of the wafer surface and the central axis of the wafer surface form a normal plane, the laser beam is parallel to the normal plane, and the laser beam irradiates the wafer surface with the Brewster angle as the incident angle.

[0071] The laser annealing scanning method provided by the embodiment of the present invention determines a scanning trajectory, which is an arc-shaped structure with an opening facing away from the incident direction of the laser spot, and includes a first low-power section, a power rising section, a high-power section, a power falling section and a second low-power section connected in sequence from one end to the other end; the light spot is controlled to scan the edge protection area of ​​the wafer surface along the first low-power section with a first power to protect the wafer edge; the light spot is controlled to scan the edge protection area of ​​the wafer surface along the power rising section to achieve power rising, avoid damage to the wafer edge caused by too fast power change, and prepare for subsequent light spot scanning of the high-power section; the light spot is controlled to scan the wafer surface along the high-power section with a second power to achieve scanning the high-power section; the light spot is controlled to scan the edge protection area of ​​the wafer surface along the power falling section to achieve power falling, avoid damage to the wafer edge caused by too fast power change, and prepare for subsequent scanning of the second low-power section; the light spot is controlled to scan the edge protection area of ​​the wafer surface along the second low-power section with a third power to protect the wafer edge; in summary, the method provided by the embodiment of the present invention realizes protection of the wafer edge by controlling the power of each scanning section of the scanning trajectory.

[0072] In the embodiment of the present invention, the power rising section includes a first power rising section, a first power constant section, and a second power rising section connected end to end in sequence, the head end of the first power rising section is connected to the end of the first low power section, and the end of the second power rising section is connected to the head end of the high power section; step S130 includes the following sub-steps:

[0073] S1302, controlling the light spot to scan the edge protection area of ​​the wafer surface along the first power rising section, wherein the scanning power of the light spot gradually increases from the first power to the fourth power;

[0074] S1304, controlling the light spot to scan the edge protection area of ​​the wafer surface along the first constant power section at a fourth power;

[0075] S1306, controlling the light spot to scan the wafer surface along the second power rising section, wherein the scanning power of the light spot gradually increases from the fourth power to the edge protection area of ​​the second power.

[0076] In this way, setting the fourth power scan to the first constant power section can play a buffering role for the subsequent high-power PID adjustment and reduce the overshoot phenomenon of PID adjustment. Figure 4 As shown, B1 and B2 in T4 are power switching sections, and the fourth power is set to control the power to rise smoothly, without overshoot in the controlled temperature and the controlled temperature is stable; T5 is a non-power switching section, and there is a rising rate that is too fast, resulting in a rapid increase in the initial temperature, a large temperature difference, and more likely to produce fragments, and it is difficult to control the temperature stability of the high-power scanning section from C1 to C2, affecting the yield and the performance of semiconductor devices in the wafer.

[0077] It should be noted that the fourth power is an intermediate value between the first power and the second power, and may also be an appropriate value near the intermediate value, that is, the appropriate value can reduce the overshoot phenomenon of PID regulation.

[0078] In the embodiment of the present invention, the power reduction section includes a first power reduction section, a second power constant section, and a second power reduction section connected end to end in sequence, the head end of the first power reduction section is connected to the end of the high power section, and the end of the second power reduction section is connected to the head end of the second low power section; step S150 includes the following sub-steps:

[0079] S1502, controlling the light spot to scan the edge protection area of ​​the wafer surface along the first power decreasing section, wherein the scanning power of the light spot gradually decreases from the second power to the fourth power;

[0080] S1504, controlling the light spot to scan the edge protection area of ​​the wafer surface along the second constant power section at a fourth power;

[0081] S1506 controls the light spot to scan the edge protection zone of the wafer surface along the second power decreasing section, wherein the scanning power of the light spot gradually decreases from the fourth power to the third power, and the third power is equal to the first power.

[0082] It should be noted that the third power may not be equal to the first power, but must be able to achieve the desired effect of the annealing process.

[0083] In an embodiment of the present invention, the scanning method further includes the following steps:

[0084] Get the width and dwell time of the light spot;

[0085] A preset speed of the light spot along the first direction is determined according to the width and the dwell time.

[0086] In this way, the preset speed of the light spot along the first direction is determined to ensure that the light spot meets the dwell time during the scanning process, achieve uniform scanning of the wafer surface, and better prevent the diffusion of dopants in the wafer in the case of multiple scans.

[0087] In the embodiment of the present invention, the scanning trajectory further includes an acceleration section, the end of the acceleration section is connected to the beginning of the first low-power section, and the acceleration section is located outside the wafer surface; before step S120, the following steps are also included:

[0088] S160, controlling the light spot to accelerate at a first power in an acceleration section, and accelerating to a preset speed at the end of the acceleration section.

[0089] In this way, the acceleration in the acceleration section ensures that the light spot can scan the wafer surface at the preset speed in the first direction.

[0090] In the embodiment of the present invention, the scanning trajectory further includes a deceleration segment, the head end of the deceleration segment is connected to the end of the second low-power segment, and the deceleration segment is located outside the wafer surface; after step S150, the following steps are also included:

[0091] S170, controlling the light spot to decelerate along the deceleration section at a third power, and decelerating to zero at the end of the deceleration section, wherein the third power is equal to the first power;

[0092] S180, controlling the light spot to move along a second direction by half the length of the light spot, wherein the second direction is parallel to the wafer surface and perpendicular to the first direction.

[0093] In this way, the light spot is prepared to scan the next track by decelerating in the deceleration section and moving down half the light spot length.

[0094] It should be noted that if Figure 5As shown, it is planned to reach the required preset speed before entering the wafer surface, and maintain a uniform speed along the first direction during the wafer surface scanning process, decelerate after exiting the wafer surface, and then accelerate in the reverse direction to reach the required preset speed before entering the wafer surface, and repeat this cycle to better prevent the diffusion of dopants in the wafer under multiple scans.

[0095] In the embodiment of the present invention, the scanning trajectory includes a first straight line segment, an arc segment, and a second straight line segment connected end to end in sequence, the first straight line segment and the arc segment are tangent to each other at a first tangent point, and the second straight line segment and the arc segment are tangent to each other at a second tangent point; step S110 includes the following sub-steps:

[0096] S1102, determine the radius of the arc segment: R=1 / 2(DL-2EPA);

[0097] S1104, determining an angle between the first tangent point and the central axis of the wafer surface, the angle being between a first angle and a second angle;

[0098] S1106, determining the first tangent point position according to the arc segment radius and included angle;

[0099] S1108, determining the position of the second tangent point according to the symmetry between the second tangent point and the first tangent point about the central axis;

[0100] S1110, determining a first straight line segment, a second straight line segment, and an arc segment trajectory according to the first tangent point position, the second tangent point position, and the arc radius;

[0101] Among them, R is the arc radius; D is the wafer diameter; L is the spot length; EPA is the radial distance of the edge protection area; the first angle is the minimum angle that meets the preset annealing requirements, and the second angle is the maximum angle limited by the maximum moving speed of the spot scanning in the second direction.

[0102] Thus, the radius and center angle of the arc segment can be obtained through the above steps. In addition, the first straight line segment is tangent to the arc segment at the first tangent point, and the second straight line segment is tangent to the arc segment at the second tangent point, so that the complete scanning trajectory can be determined.

[0103] In an embodiment of the present invention, the scanning method further includes the following steps:

[0104] Control the light spot to scan in the reverse direction along the scanning trajectory.

[0105] So, like Figure 6 As shown, due to the displacement of the light spot along the second direction, there is a partial area 301 that has only undergone one annealing process. By controlling the light spot to perform reverse scanning along the scanning track, as shown in FIG. Figure 7 As shown, the partial region 302 has completed the secondary annealing process.

[0106] It should be noted that if Figure 3 As shown, the overall scanning method is to scan from N to S in sequence, but is not limited to the above scanning sequence, and can also be as follows Figure 8 As shown, the overall scanning method is from S to N, one scan.

[0107] It should be noted that if Fig. 9 As shown, multiple partitions can be defined according to current process requirements, such as Fig. 9 There are four partitions in the system, namely F1, F2, F3, and F4, and the required area range is planned for each partition. In the actual process, the laser power value, scanning sequence, scanning range, dwell time, etc. required for the scanning segment can be set separately for each area.

[0108] In the embodiment of the present invention, Figure 3 As shown, an arc segment PQ with a central angle of 2θ and a radius of R, a straight line segment L1 tangent to the arc segment at point P, and a straight line segment L2 tangent to the arc segment at point Q form a scanning track covering the entire wafer surface.

[0109] The method to calculate the scanning trajectory is as follows:

[0110]

[0111] y=kx+Rcosθ+kRsinθ (1-2)

[0112] x 2 +y 2 =R 2 (1-3)

[0113] Wherein, L is the effective spot length acting on the wafer surface during beam scanning; D is the wafer diameter; EPA is the radial distance of the wafer edge protection area; point P is the intersection of the straight line segment and the arc segment (-Rsinθ, Rcosθ); the polar angle θ is the angle between the first tangent point and the central axis of the wafer surface; the above scanning trajectory is the motion trajectory taking the midpoint of the length direction of the spot as an example; formula (1-1) is the arc segment radius formula, formula (1-2) is the straight line segment L1 formula, and formula (1-3) is the arc segment formula.

[0114] Further, from the straight line distance formula of the origin (0,0) to the point P (-Rsinθ, Rcosθ), we can get:

[0115]

[0116] Simplifying further, we can get

[0117]

[0118] Formula (1-5) can be used to obtain the slope k1 of the straight line segment L1.

[0119] Substituting the known spot length L, polar angle θ, EPA value and slope k1 of straight line segment L1, the first trajectory can be planned:

[0120] y=k1x+Rcosθ+kRsinθ (1-6)

[0121] y=-k1x+Rcosθ+kRsinθ (1-7)

[0122] x 2 +y 2 =R 2 (1-3)

[0123] Among them, formula (1-6) is the trajectory formula of straight line segment L1, and formula (1-7) is the trajectory formula of straight line segment L2.

[0124] Shift the first trajectory downward by half the spot length, and you get the formula for the second trajectory:

[0125]

[0126]

[0127]

[0128] Among them, formula (1-8) is the trajectory formula of the second trajectory straight line segment L1, formula (1-9) is the trajectory formula of the second trajectory straight line segment L2, and formula (1-10) is the trajectory formula of the second trajectory arc segment.

[0129] Similarly, the subsequent trajectory formula can be obtained.

[0130] In addition, the number of required scanning track stripes N is calculated according to the arc radius and the downward movement distance. The specific calculation method is as follows:

[0131]

[0132] Among them, formula (1-11) is the calculation formula for the number N of scanning track stripes.

[0133] The embodiment of the present invention provides a method for determining a scanning trajectory control node, and the specific method is as follows:

[0134] According to the scanning trajectory and the length of the light spot, the motion trajectories of the proximal and distal ends of the light spot are determined. The motion trajectory of the proximal end intersects with the outer edge of the wafer at a first intersection, and the motion trajectory of the distal end intersects with the outer edge of the wafer at a second intersection. According to the first intersection, it can be determined that the midpoint of the light spot corresponding to the intersection is located at a specific position of the scanning trajectory. Similarly, according to the second intersection, it can be determined that the midpoint of the light spot corresponding to the intersection is located at a specific position of the scanning trajectory, thereby determining the positions of W2, W3, W10 and W11; wherein W2 to W3 are the first low-power segment, and W10 to W11 are the second low-power segment.

[0135] Furthermore, the positions of W1 and W12 are determined according to the speed change parameters; wherein W1 to W2 is an acceleration section, and W11 to W12 is a deceleration section.

[0136] Furthermore, according to the power variation parameters, the light spot scanning speed and the radial distance of the edge protection area, the positions of W4, W5, W6, W7, W8 and W9 are determined; wherein W3 to W4 is the first power rising section, W4 to W5 is the first power constant section, W5 to W6 is the second power rising section, W6 to W7 is the high power section, W7 to W8 is the first power decreasing section, W8 to W9 is the second power constant section, and W9 to W10 is the second power decreasing section.

[0137] The embodiment of the present invention provides a method for determining a polar angle boundary range, and the specific method is as follows:

[0138] (1) Determine the minimum value of the polar angle boundary: Determine the minimum value of the polar angle that satisfies the laser annealing effect through experimental testing.

[0139] For example, Fig.10 As shown in the figure, T1 is the effect diagram of the polar angle θ = 47°, T2 is the effect diagram of the polar angle θ = 52°, and T3 is the effect diagram of the polar angle θ = 57°. The first rise of the curve in the figure is the first power rise section to perform the power increase function, and the second rise of the curve is the scanning section for high-temperature annealing process. It can be seen from the comparison diagram that as the angle increases, the more stable the power switching is, the better the temperature control effect of the high-power section is. The temperature control of T3 is stable and gentle, which meets the laser annealing effect, so θ min =57° is the minimum polar angle.

[0140] (2) Determine the maximum value of the polar angle boundary: determine the maximum value of the polar angle by the maximum value of the moving speed in the second direction.

[0141] For example, Fig.11 As shown, the sum of the first direction preset speed V1 and the second direction preset speed V2 is the laser scanning speed V. It is known that the first direction preset speed V1 is a finite value determined by the spot residence time and the spot width. The second direction preset speed V2 has a maximum value V3. According to the formula:

[0142]

[0143] Among them, formula (1-12) is the maximum polar angle calculation formula, which determines the maximum value of the polar angle boundary.

[0144] The embodiment of the present invention provides a laser annealing scanning device, which is used to implement the above scanning method, such as Figure 2 As shown, the scanning device includes:

[0145] A determination module 210, configured to determine a scanning trajectory;

[0146] The control module 220 is used to control the light spot to scan the edge protection zone of the wafer surface along the first low power segment at a first power, control the light spot to scan the edge protection zone of the wafer surface along the power rising segment, control the light spot to scan the edge protection zone of the wafer surface along the second power segment at a high power segment, control the light spot to scan the edge protection zone of the wafer surface along the power falling segment, and control the light spot to scan the edge protection zone of the wafer surface along the second low power segment at a third power.

[0147] The control module 220 includes:

[0148] PC end 2202, used to generate a first control command and a second control command;

[0149] The PXI system 2204 is used to receive the first control command and control the laser power;

[0150] The controller 2206 is used to receive the second control command and control the motion platform.

[0151] Specifically, Fig.12 As shown, the device includes: a PC terminal 1, a controller 2, a PXI system 3, a laser 4, a motion platform 5 and a wafer 6. The laser 4 is used to generate a laser beam, the motion platform 5 is used to fix the wafer position, the controller 2 is used to control the running trajectory of the motion platform 1 through a signal S2, the PC terminal 1 is used to control the output power of the laser 4, and the PXI system 4 is used to further control the power of the light beam 101 through a signal S1, so as to achieve the effect of uniform heating of the surface of the wafer 6 by the light beam.

[0152] Of course, those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be implemented by instructing the control device through a computer, and the program can be stored in a computer-readable storage medium. When the program is executed, it may include the processes of the above-mentioned method embodiments, wherein the storage medium may be a memory, a disk, an optical disk, etc.

[0153] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

[0154] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0155] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the laser annealing scanning device disclosed in the embodiment, since it corresponds to the laser annealing scanning method disclosed in the above embodiment, the description is relatively simple, and the relevant parts can be referred to the method part description.

[0156] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A laser annealing scanning method, characterized in that: The scanning method comprises the following steps: Determine a scanning trajectory, wherein the scanning trajectory is an arc-shaped structure with an opening facing away from the incident direction of the laser spot, and includes a first low-power section, a power increase section, a high-power section, a power decrease section, and a second low-power section connected in sequence from one end to the other end; Controlling the light spot to scan the edge protection zone of the wafer surface along the first low-power section at the first power, and the light spot at the end position of the first low-power section just completely enters the edge protection zone of the wafer surface, and the edge protection zone is a circular ring area radially inward from the outer edge of the wafer; Controlling the light spot to scan the edge protection area of ​​the wafer surface along the power rising section, wherein the scanning power of the light spot gradually increases from the first power to the second power, and the light spot at the end position of the power rising section is located in the edge protection area; Controlling the light spot to scan the wafer surface along the high power section at the second power, the light spot at the head end position of the high power section begins to leave the edge protection area and enter the central scanning area, and the light spot at the end position of the high power section has left the central scanning area and entered the edge protection area; Controlling the light spot to scan the edge protection area of ​​the wafer surface along the power decreasing section, wherein the scanning power of the light spot gradually decreases from the second power to a third power, and the light spot at the head end of the power decreasing section is located in the edge protection area; The light spot is controlled to scan the edge protection area of ​​the wafer surface along the second low-power section at the third power, and the light spot at the end position of the second low-power section completely leaves the wafer surface.

2. The laser annealing scanning method according to claim 1, characterized in that: The power rising section comprises a first power rising section, a first power constant section, and a second power rising section which are connected end to end in sequence, the head end of the first power rising section is connected to the end of the first low power section, and the end of the second power rising section is connected to the head end of the high power section; controlling the light spot to scan the edge protection area of ​​the wafer surface along the power rising section comprises the following steps: Controlling the light spot to scan the edge protection area of ​​the wafer surface along the first power rising section, wherein the scanning power of the light spot gradually increases from the first power to the fourth power; Controlling the light spot to scan the edge protection zone of the wafer surface along the first constant power section at the fourth power; The light spot is controlled to scan the edge protection area of ​​the wafer surface along the second power rising section, wherein the scanning power of the light spot gradually increases from the fourth power to the second power.

3. The laser annealing scanning method according to claim 2, characterized in that: The power reduction section comprises a first power reduction section, a second constant power section and a second power reduction section which are connected end to end in sequence, the head end of the first power reduction section is connected to the end of the high power section, and the end of the second power reduction section is connected to the head end of the second low power section; controlling the light spot to scan the edge protection area of ​​the wafer surface along the power reduction section comprises the following steps: Controlling the light spot to scan the edge protection area of ​​the wafer surface along the first power decreasing section, wherein the scanning power of the light spot gradually decreases from the second power to the fourth power; Controlling the light spot to scan the edge protection zone of the wafer surface along the second constant power section at the fourth power; The light spot is controlled to scan the edge protection area of ​​the wafer surface along the second power decreasing section, wherein the scanning power of the light spot gradually decreases from the fourth power to the third power, and the third power is equal to the first power.

4. The laser annealing scanning method according to claim 1, characterized in that: The scanning method further comprises the following steps: Acquiring the width of the light spot and the dwell time of the light spot; A preset speed of the light spot along a first direction is determined according to the width and the dwell time.

5. The laser annealing scanning method according to claim 4, characterized in that: The scanning trajectory further includes an acceleration section, the end of which is connected to the beginning of the first low-power section, and the acceleration section is located outside the wafer surface; before the step of controlling the light spot to scan the edge protection area of ​​the wafer surface along the first low-power section at the first power, the following steps are also included: The light spot is controlled to accelerate at a first power in the acceleration section, and is accelerated to the preset speed at the end of the acceleration section.

6. The laser annealing scanning method according to claim 4, characterized in that: The scanning trajectory further includes a speed reduction section, the head end of the speed reduction section is connected to the end of the second low-power section, and the speed reduction section is located outside the wafer surface; after the step of controlling the light spot to scan the edge protection area of ​​the wafer surface along the power reduction section, the following steps are also included: Controlling the light spot to decelerate along the deceleration section at a third power and decelerate to zero at the end of the deceleration section, wherein the third power is equal to the first power; The light spot is controlled to move along a second direction by half the length of the light spot, wherein the second direction is parallel to the wafer surface and perpendicular to the first direction.

7. The laser annealing scanning method according to claim 6, characterized in that: The scanning trajectory includes a first straight line segment, a circular arc segment, and a second straight line segment connected end to end in sequence, the first straight line segment is tangent to the circular arc segment at a first tangent point, and the second straight line segment is tangent to the circular arc segment at a second tangent point; determining the scanning trajectory includes the following steps: Determine the radius of the arc segment: R = 1 / 2 (DL-2EPA); Determine an angle between the first tangent point and a central axis of the wafer surface, wherein the angle is between a first angle and a second angle; Determine the first tangent point position according to the arc segment radius and the included angle; Determine the position of the second tangent point according to the symmetry between the second tangent point and the first tangent point about the central axis; Determine the first straight line segment, the second straight line segment and the arc segment trajectory according to the first tangent point position, the second tangent point position and the arc radius; Among them, R is the arc radius; D is the wafer diameter; L is the spot length; EPA is the radial distance of the edge protection area; the first angle is the minimum angle that meets the preset annealing requirements, and the second angle is the maximum angle limited by the maximum moving speed of the spot scanning in the second direction.

8. The laser annealing scanning method according to any one of claims 1 to 7, characterized in that: The scanning method further comprises the following steps: The light spot is controlled to perform reverse scanning along the scanning track.

9. A laser annealing scanning device, characterized in that: Used to implement the scanning method according to any one of claims 1 to 8, the scanning device comprises: A determination module, used for determining a scanning trajectory; A control module is used to control the light spot to scan the edge protection zone of the wafer surface along the first low power section at the first power, control the light spot to scan the edge protection zone of the wafer surface along the power rising section, control the light spot to scan the edge protection zone of the wafer surface along the second high power section, control the light spot to scan the edge protection zone of the wafer surface along the power falling section, and control the light spot to scan the edge protection zone of the wafer surface along the second low power section at the third power.

10. The laser annealing scanning device according to claim 9, characterized in that: The control module comprises: The PC side is used to generate a first control command and a second control command; A PXI system, used for receiving the first control command and controlling the laser power; The controller is used to receive the second control command and control the motion platform.

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