A laser annealing method and a semiconductor device

Abstract

This application discloses a laser annealing method and a semiconductor device. The laser annealing method includes: providing a substrate; scanning at least one row on the substrate with a laser beam, wherein scanning one row on the substrate with a laser beam includes a periodic operation, the periodic operation including the laser beam irradiating the substrate relatively stationary, the laser beam stopping irradiation, and the laser beam source moving relative to the substrate along the row direction; wherein the irradiation area of ​​the laser beam on the substrate is rectangular, the width of the rectangle is smaller than the width of the substrate in the row direction, and the energy density distribution of the laser beam is an isosceles trapezoid, the irradiation area of ​​the laser beam on the substrate includes a first slope region, a uniform region, and a second slope region corresponding to the isosceles trapezoid. The laser annealing method of this application, by adjusting the overlap range of the irradiation area of ​​the laser beam, enables the laser heat to be uniformly transferred to the semiconductor device during laser annealing, resulting in uniform amorphous silicon crystallization on the semiconductor device.

Description

Technical Field

[0001] This application relates to the field of semiconductor processing technology, and more specifically to a laser annealing method and a semiconductor device. Background Technology

[0002] Laser annealing uses a concentrated laser beam to locally heat a semiconductor material to a predetermined temperature. The laser energy absorbed by the semiconductor material is converted into heat, causing a rapid local temperature rise. Laser annealing can be used for impurity activation or semiconductor material crystallization. Compared to traditional annealing, laser annealing has a smaller thermal budget, which can significantly reduce heat diffusion and thermal strain. However, in related technologies, laser annealing can result in uneven heat transfer to the semiconductor material. For example, when using laser annealing to crystallize amorphous silicon into polycrystalline silicon, it can easily lead to uneven grain size after crystallization.

[0003] Therefore, how to ensure that laser energy can be uniformly transferred to semiconductor materials is a technical problem that urgently needs to be solved. Summary of the Invention

[0004] The summary section introduces a series of simplified concepts, which will be further explained in detail in the detailed description section. This summary section is not intended to limit the key and essential technical features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0005] One aspect of this application provides a laser annealing method, the method comprising: providing a substrate; scanning at least one row on the substrate with a laser beam, wherein scanning one row on the substrate with the laser beam includes a periodic operation, the periodic operation including the laser beam irradiating the substrate relatively stationary with respect to the substrate, the laser beam stopping irradiation, and the light source of the laser beam moving relative to the substrate along the row direction; wherein the irradiation area of ​​the laser beam on the substrate is rectangular, the width of the rectangle is smaller than the width of the substrate in the row direction, and the energy density distribution of the laser beam is an isosceles trapezoid, the irradiation area of ​​the laser beam on the substrate includes a first slope region, a uniform region, and a second slope region corresponding to the isosceles trapezoid; the scanning one row on the substrate with the laser beam includes the first slope region in one periodic operation coinciding with the second slope region in another periodic operation.

[0006] For example, when the laser beam stops irradiating, the substrate moves relative to the light source in the row direction by a preset step length.

[0007] For example, the relative movement of the light source and the substrate along the row direction includes: the light source being stationary and the substrate moving along the row direction.

[0008] For example, the substrate surface includes a semiconductor material.

[0009] For example, the semiconductor material includes amorphous silicon.

[0010] For example, the method further includes: adjusting the preset step size according to the annealing temperature.

[0011] For example, the method further includes adjusting the laser energy density of the laser beam according to the annealing temperature.

[0012] For example, the method further includes: adjusting the width of the rectangle in the row direction according to the annealing temperature.

[0013] For example, the method further includes: adjusting the ratio of the width of the uniform region to the width of the irradiated region in the row direction.

[0014] This application also provides a semiconductor device, including a semiconductor device prepared by the above-described laser annealing method.

[0015] According to the laser annealing method and semiconductor device provided in this application, the laser annealing method of this application adjusts the overlap range of the irradiation area of ​​the laser beam so that the laser heat can be uniformly transferred to the semiconductor device during laser annealing, thereby making the amorphous silicon crystals on the semiconductor device uniform. Attached Figure Description

[0016] The following drawings, which are incorporated herein by reference and are used to understand this application, illustrate embodiments of the invention and their descriptions to explain the principles of the invention.

[0017] In the attached image:

[0018] Figure 1 This is a schematic diagram of the laser beam scanning path in related technologies;

[0019] Figures 2(a)-2(d) This is a schematic diagram of the laser beam scanning path in related technologies;

[0020] Figure 3 This is a schematic flowchart of a laser annealing method according to an embodiment of this application;

[0021] Figure 4 This is a schematic diagram of the energy distribution along the beam path according to an embodiment of this application;

[0022] Figure 5 This is a schematic diagram showing the complete overlap of a first slope region and a second slope region according to an embodiment of this application.

[0023] Figures 6(a)-6(d)This is a schematic diagram of a laser beam scanning path according to an embodiment of this application. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this application more apparent, exemplary embodiments according to this application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments of this application. It should be understood that this application is not limited to the exemplary embodiments described herein. Based on the embodiments of this application described herein, all other embodiments obtained by those skilled in the art without inventive effort should fall within the protection scope of this application.

[0025] The following description provides numerous specific details to offer a more thorough understanding of this application. However, it will be apparent to those skilled in the art that this application can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described to avoid confusion with this application.

[0026] It should be understood that this application can be implemented in various forms and should not be construed as being limited to the embodiments set forth herein. Rather, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of this application to those skilled in the art.

[0027] To fully understand this application, a detailed structure will be presented in the following description to illustrate the technical solution proposed in this application. Optional embodiments of this application are described in detail below; however, in addition to these detailed descriptions, this application may have other implementation methods.

[0028] The following detailed description of some embodiments of this application is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0029] In the manufacturing process of chips or panels, laser annealing typically uses a high-energy-density laser beam to irradiate the surface of a semiconductor film, rapidly heating the irradiated area within a very short time. This causes the semiconductor film material to melt and crystallize, thus achieving crystallization. (See also...) Figure 1 In existing technologies, the laser beam source 10 used for annealing irradiates a rectangular area on the substrate. The annealing process involves repetitive actions: after each stationary irradiation of a region on the film layer, irradiation is stopped and the laser moves along the scanning direction by a preset step size, with at least two adjacent irradiated regions overlapping. Ideally, the energy density distribution of the laser beam should be uniform to ensure uniform heating of the semiconductor material surface. However, the optical path system in related technologies cannot achieve a completely uniform energy density distribution of the laser beam. For example, in the scanning direction, the energy density distribution resembles a trapezoid with slopes on both sides. Figures 2(a)-2(d) As shown in Figure 2(a), the laser beam scanning process in the relevant technology includes: first, as shown in Figure 2(a), the region between positions α and β receives illumination from a uniform laser beam region and a sloped region; then, a second and a third illumination are performed, as shown in Figure 2(a). Figures 2(b)-2(c) As shown in Figure 2(d), the region between positions α and β receives a uniform laser beam irradiation once; in the fourth irradiation, the region between positions α and β receives both a uniform laser beam irradiation and an irradiation of a sloping region. Since the sloping regions in the first and fourth irradiations can only partially overlap or not overlap, the amorphous silicon in the region between positions α and β in the related technology experiences uneven heating.

[0030] To ensure uniform laser annealing, this application provides a laser annealing method, see [link to relevant documentation]. Figure 1 , Figure 3 as well as Figure 4 As shown, the laser annealing method includes:

[0031] Step S110: Provide a substrate.

[0032] For example, the substrate surface includes a semiconductor material, which may include amorphous silicon. However, it is not limited to this; the substrate may also be a semiconductor substrate that has undergone ion implantation doping, depending on the specific circumstances.

[0033] For example, the substrate may include a base and a film layer formed of semiconductor material above the base. The base may be any suitable semiconductor base, such as a silicon base, and may also be at least one of the following materials: Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP or other III / V compound semiconductors, and may also include multilayer structures formed of these semiconductor materials, or may be silicon on insulator (SOI), silicon on insulator stacked (SSOI), silicon on insulator stacked germanium (S-SiGeOI), silicon on insulator germanium (SiGeOI) and germanium on insulator (GeOI), or may also be double-side polished wafers (DSP). The base may also be an insulating base such as a ceramic substrate of alumina, quartz or glass substrate.

[0034] Step S120: Scan at least one row on the substrate with a laser beam.

[0035] The process of scanning a row on a substrate with a laser beam includes a periodic operation, which includes the laser beam irradiating the substrate while it is relatively stationary, the laser beam stopping irradiation, and the laser beam source moving relative to the substrate along the row direction. The irradiation area on the substrate is rectangular, and in the row direction, the width of the rectangle is smaller than the width of the substrate. The energy density distribution of the laser beam is an isosceles trapezoid. The irradiation area on the substrate includes a first slope area, a uniform area, and a second slope area corresponding to the isosceles trapezoid. The scanning of a row on the substrate with a laser beam includes the first slope area in one periodic operation coinciding with the second slope area in another periodic operation.

[0036] As an example, the light source can be an excimer laser, which may include elements such as microlens arrays, Fourier lenses, mirrors, and apertures, enabling the focusing, shaping, and control of laser energy distribution of the laser beam. For example, when incident light irradiates the microlens array, the array can be considered as a multi-source array. The image of each microlens unit, i.e., the source array unit, is superimposed on the same position on the beam-averaging plane after passing through the Fourier lens. Since the image contour of the source array unit is consistent with the pupil contour of the microlens unit, the superimposed image contour (i.e., the spot shape) on the beam-averaging plane will also be consistent with the pupil contour of the microlens unit. It should be noted that different spot shapes can be obtained depending on the aperture type of the microlens unit; for example, a rectangular microlens can make the irradiation area of ​​the laser beam on the substrate rectangular.

[0037] For example, such as Figure 4 As shown, the horizontal axis direction is both the row direction and the X-direction, as well as the scanning direction. The laser beam profile is an isosceles trapezoid. The irradiation area of ​​the laser beam on the substrate includes a first slope region, a uniform region, and a second slope region located sequentially in the row direction. In one embodiment, the width ratio of the first slope region, the uniform region, and the second slope region in the row direction can be achieved by adjusting the optical path of the light source, for example, by adjusting components such as microlens arrays, Fourier lenses, mirrors, and apertures.

[0038] It should be noted that, as Figure 5 As shown, when the first and second slope regions completely overlap, the sum of the two laser energies is the same at any position within the overlapping region. For example, the energy in the first slope region corresponding to position x is h1, and the energy in the second slope region corresponding to position x is h2. The sum of h1 and h2 is H. Therefore, by ensuring that the first slope region in one cycle coincides with the second slope region in another cycle, i.e., completely overlaps, it is possible to achieve uniform laser energy received at any position within the entire scanning line region, thus facilitating the uniform crystallization of amorphous silicon on semiconductor devices.

[0039] It is understandable that the larger the width of the first slope region and the second slope region, the easier it is to achieve overlap between the first slope region in one cycle and the second slope region in another cycle, thus reducing the difficulty of achieving uniform laser annealing. In one embodiment, the width of the uniform region in the row direction is an integer multiple of the width of the first slope region or the width of the second slope region.

[0040] The laser annealing method of this application adjusts the overlap range of the irradiation area of ​​the laser beam so that the laser heat can be uniformly transferred to the semiconductor device during laser annealing, resulting in uniform amorphous silicon crystallization on the semiconductor device.

[0041] In some embodiments, when the laser beam stops irradiating, the substrate moves relative to the light source along the row direction by a preset step length. The preset step length ensures that, with a fixed step length, the first slope region in the irradiated area of ​​each cycle overlaps with another second slope region within a certain range. It can be understood that when the step length is the preset step length, and the first slope region in one cycle overlaps with the second slope region in another cycle, the sum of the widths of the first slope region and the uniform region in the row direction is an integer multiple of the preset step length.

[0042] Next, taking the region between positions α and β being irradiated four times in one cycle as an example, the laser annealing process of this application will be explained. See [link to relevant documentation]. Figures 6(a)-6(d) The first irradiation, as shown in Figure 6(a), occurs in the region between positions α and β, receiving complete irradiation of the first slope region; the second and third irradiations, as shown in Figure 6(a), occur in the region between positions α and β. Figures 6(b)-6(c) As shown in Figure 6(d), the region between positions α and β receives a uniform laser beam illumination once; in the fourth illumination, the region between positions α and β receives a complete second-slope illumination. Thus, the illumination from the first and second sloped regions received by the region between positions α and β is completely overlapping, and the laser energy received at any position within the region between positions α and β is uniform, facilitating the uniform crystallization of amorphous silicon on the semiconductor device.

[0043] As an example, the preset step size can be precisely controlled by the control system of the laser annealing equipment. The control system can automatically calculate and adjust the relative movement distance between the laser beam source and the substrate based on preset parameters. Alternatively, the preset step size can be determined manually.

[0044] In some embodiments, the relative movement between the light source and the substrate along the row direction includes: the light source being stationary while the substrate moves along the row direction, but is not limited thereto.

[0045] As an example, the relative movement between the light source and the substrate along the row direction can also include: the substrate remaining stationary while the light source moves along the row direction. Specifically, which part of the light source and substrate moves depends on the specific circumstances.

[0046] In some embodiments, the laser annealing method further includes adjusting the laser energy density of the laser beam according to the annealing temperature.

[0047] It should be noted that the annealing temperature can be determined based on the material properties of the substrate and the required performance.

[0048] In this embodiment, by precisely controlling the laser energy density of the laser beam, the annealing temperature can be accurately reached, ensuring that the laser annealing achieves the predetermined effect, thereby optimizing the structure and performance of the semiconductor device.

[0049] In some embodiments, the laser annealing method further includes adjusting a preset step size according to the annealing temperature.

[0050] It should be noted that higher annealing temperatures require higher energy laser irradiation. When the energy density of a single laser irradiation is limited, using a smaller preset step size can ensure that the substrate can quickly and uniformly reach the required temperature. Conversely, lower annealing temperatures require a larger preset step size.

[0051] In this embodiment, by adjusting the preset step size, the heating efficiency can be optimized to ensure the effect of laser annealing, thereby improving the stability of the overall process.

[0052] In some embodiments, the laser annealing method further includes: adjusting the width of the rectangle in the row direction according to the annealing temperature.

[0053] It should be noted that when a higher annealing temperature is required, the width of the rectangle in the row direction can be increased, so that the same position is irradiated more times; when a lower annealing temperature is required, the width of the rectangle in the row direction can be decreased.

[0054] In this embodiment, by adjusting the width of the rectangle in the row direction, it is easier to control the heating efficiency and optimize the temperature distribution, thereby improving the annealing efficiency.

[0055] In some embodiments, the laser annealing method further includes: adjusting the time for laser irradiation of the substrate during the cycle operation according to the annealing temperature.

[0056] In this embodiment, by adjusting the laser irradiation time, the heating temperature and duration of the irradiated area during laser annealing can be precisely controlled, making it easier to achieve the preset annealing effect.

[0057] In some embodiments, the laser annealing method further includes: adjusting the ratio of the width of the uniform region to the width of the irradiated region in the row direction.

[0058] In this embodiment, by adjusting the width ratio of the uniform region and the irradiation region in the row direction, the first slope region and the second slope region within the irradiation region can be easily made to completely overlap, thereby improving the annealing uniformity, reducing the scrap rate caused by the large overlap difference between the first slope region and the second slope region, and improving the product yield.

[0059] It is understandable that adjusting the preset step size, laser energy density, width of the rectangle in the row direction, time of laser irradiation of the substrate during the periodic operation, and the ratio of the width of the uniform area and the irradiated area in the row direction can be used simultaneously to achieve the expected annealing temperature.

[0060] This application also provides a semiconductor device, including a semiconductor device prepared using the laser annealing method described above.

[0061] The semiconductor device can be any electronic product or device such as a mobile phone, tablet computer, laptop computer, netbook, game console, television, VCD, DVD, navigator, camera, camcorder, voice recorder, MP3, MP4, PSP, etc., or it can be an intermediate product with the above-mentioned semiconductor device, such as a mobile phone motherboard with the integrated circuit.

[0062] Although exemplary embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above exemplary embodiments are merely illustrative and are not intended to limit the scope of this application. Various changes and modifications can be made therein by those skilled in the art without departing from the scope and spirit of this application. All such changes and modifications are intended to be included within the scope of this application as claimed in the appended claims.

[0063] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0064] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another device, or some features may be ignored or not executed.

[0065] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of this application may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0066] Similarly, it should be understood that, in order to simplify this application and aid in understanding one or more aspects of the various applications, features of this application are sometimes grouped together in a single embodiment, figure, or description thereof in the description of exemplary embodiments of this application. However, this approach should not be construed as reflecting an intention that the claimed application requires more features than are expressly recited in each claim. Rather, as reflected in the corresponding claims, the inventive point lies in solving the corresponding technical problem with fewer features than all features of a single disclosed embodiment. Therefore, the claims following the detailed description are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of this application.

[0067] Those skilled in the art will understand that, apart from the mutual exclusion of features, all features disclosed in this specification (including the accompanying claims, abstract, and drawings) and all processes or units of any method or apparatus so disclosed can be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature that serves the same, equivalent, or similar purpose.

[0068] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

[0069] The various component embodiments of this application can be implemented in hardware, or as software modules running on one or more processors, or a combination thereof. Those skilled in the art will understand that microprocessors or digital signal processors (DSPs) can be used in practice to implement some or all of the functions of some modules according to the embodiments of this application. This application can also be implemented as an apparatus program (e.g., a computer program and computer program product) for performing part or all of the methods described herein. Such an implementation of this application can be stored on a computer-readable medium, or can be in the form of one or more signals. Such signals can be downloaded from an Internet website, provided on a carrier signal, or provided in any other form.

[0070] It should be noted that the above embodiments are illustrative of this application and not restrictive, and that those skilled in the art can devise alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses should not be construed as limiting the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. This application can be implemented by means of hardware comprising several different elements and by means of a suitably programmed computer. In the unit claims enumerating several means, several of these means may be embodied by the same item of hardware. The use of the words first, second, and third, etc., does not indicate any order. These words can be interpreted as names.

[0071] The above description is merely a specific embodiment or illustration of the embodiments of this application. The scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. The scope of protection of this application shall be determined by the scope of the claims.

Claims

1. A laser annealing method, characterized in that, The method includes: Provide substrate; A laser beam is used to scan at least one row on the substrate, wherein scanning one row on the substrate with the laser beam includes a periodic operation, the periodic operation including the laser beam irradiating the substrate relatively stationary, the laser beam stopping irradiation, and the light source of the laser beam moving relative to the substrate along the row direction; wherein... The irradiation area of ​​the laser beam on the substrate is rectangular. In the row direction, the width of the rectangle is smaller than the width of the substrate, and the energy density distribution of the laser beam is an isosceles trapezoid. The irradiation area of ​​the laser beam on the substrate includes a first slope region, a uniform region, and a second slope region corresponding to the isosceles trapezoid. The laser beam scanning a row on the substrate includes the first slope region in one cycle completely overlapping the second slope region in another cycle, such that the sum of the two laser energies received at any position within the overlapping region is the same.

2. The laser annealing method as described in claim 1, characterized in that, When the laser beam stops irradiating, the substrate moves relative to the light source in the row direction by a preset step length.

3. The laser annealing method as described in claim 1, characterized in that, The light source moves relative to the substrate along the row direction, including: The light source is stationary, while the substrate moves along the row direction.

4. The laser annealing method as described in claim 1, characterized in that, The substrate surface includes a semiconductor material.

5. The laser annealing method as described in claim 4, characterized in that, The semiconductor material includes amorphous silicon.

6. The laser annealing method as described in claim 2, characterized in that, The method further includes adjusting the preset step size according to the annealing temperature.

7. The laser annealing method as described in claim 1, characterized in that, The method further includes adjusting the laser energy density of the laser beam according to the annealing temperature.

8. The laser annealing method as described in claim 1, characterized in that, The method further includes adjusting the width of the rectangle in the row direction according to the annealing temperature.

9. The laser annealing method as described in claim 1, characterized in that, The method further includes adjusting the ratio of the width of the uniform region to the width of the irradiated region in the row direction.

10. A semiconductor device, characterized in that, include: Semiconductor devices prepared by the laser annealing method as described in any one of claims 1-9.

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