Laser annealing method and semiconductor device

Abstract

The invention discloses a laser annealing method and a semiconductor device. The laser annealing method comprises the following steps: providing a substrate; scanning at least one line on the substrate by using the laser beam, the scanning of one line on the substrate by using the laser beam comprises a periodic action, and the periodic action comprises that the laser beam and the substrate statically irradiate the substrate relative to each other, the laser beam stops irradiating, and a light source of the laser beam and the substrate move relative to each other along the line 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, the energy density distribution of the laser beam is an isosceles trapezoid, and the irradiation area of the laser beam on the substrate comprises a first gradient area, a uniform area and a second gradient area corresponding to the isosceles trapezoid. According to the laser annealing method, by adjusting the overlapping range of the irradiation areas of the laser beams, laser heat can be uniformly transmitted to the semiconductor device during laser annealing, so that amorphous silicon on the semiconductor device is uniformly crystallized.

Description

Technical Field

[0001] The present application relates to the field of semiconductor processing technology, and in particular to a laser annealing method and a semiconductor device. Background Art

[0002] Laser annealing is the use of 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 energy, resulting in rapid local temperature rise. Laser annealing can be used for impurity activation or crystallization of semiconductor materials. Compared with traditional annealing, laser annealing has a small thermal budget, which can greatly reduce heat diffusion and reduce thermal strain. However, laser annealing in related technologies is not uniform enough to transfer laser heat to the semiconductor material. For example, when laser annealing is used to crystallize amorphous silicon to form polycrystalline silicon, it is easy to cause uneven grain size after crystallization.

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

[0004] A series of simplified concepts are introduced in the Summary of the Invention section, which will be further described in detail in the Detailed Description of the Invention section. The Summary of the Invention section of this application does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0005] One aspect of the present 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 a row on the substrate with the laser beam comprises a periodic action, the periodic action comprises irradiating the substrate with the laser beam relatively still and the laser beam stops irradiating, and the light source of the laser beam moves relative to the substrate along a row direction; wherein the irradiation area of ​​the laser beam on the substrate is a rectangle, the width of the rectangle in the row direction is smaller than the width of the substrate, and the energy density distribution of the laser beam is an isosceles trapezoid, and the irradiation area of ​​the laser beam on the substrate comprises a first slope area, a uniform area, and a second slope area corresponding to the isosceles trapezoid; scanning a row on the substrate with the laser beam comprises that the first slope area in one periodic action overlaps with the second slope area in another periodic action.

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

[0007] Exemplarily, the light source and the substrate move relative to each other along the row direction, including: the light source is stationary, and the substrate moves along the row direction.

[0008] Illustratively, the substrate surface comprises a semiconductor material.

[0009] Exemplarily, the semiconductor material includes amorphous silicon.

[0010] Exemplarily, the method further includes: adjusting the preset step length according to the annealing temperature.

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

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

[0013] Exemplarily, the method further includes: adjusting the ratio between the widths of the uniform area and the irradiated area in the row direction.

[0014] The present application also provides a semiconductor device, including: a semiconductor device prepared by the above-mentioned laser annealing method.

[0015] According to the laser annealing method and semiconductor device provided in the present application, the laser annealing method of the present application adjusts the overlapping range of the irradiation area of ​​the laser beam so that the laser heat can be evenly transferred to the semiconductor device during laser annealing, thereby making the amorphous silicon on the semiconductor device crystallize evenly. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The following drawings of the present application are used as a part of the present application for understanding the present application. The drawings show the embodiments of the present application and their descriptions, which are used to explain the principle of the present application.

[0017] In the attached figure:

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

[0019] Figure 2(a)-Figure 2(d) A schematic diagram of a laser beam scanning path in the related art;

[0020] Figure 3 is a schematic flow chart of a laser annealing method according to an embodiment of the present application;

[0021] Figure 4 is a schematic diagram of energy distribution in the direction of a light beam according to an embodiment of the present application;

[0022] Figure 5 This is a schematic diagram of a first slope area and a second slope area completely overlapping according to an embodiment of the present application;

[0023] Figure 6(a)-Figure 6(d)FIG. 4 is a schematic diagram of a laser beam scanning path according to an embodiment of the present application. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present application more obvious, the example embodiments according to the present application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application, and it should be understood that the present application is not limited to the example embodiments described herein. Based on the embodiments of the present application described in the present application, all other embodiments obtained by those skilled in the art without creative work should fall within the scope of protection of the present application.

[0025] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present application. However, it is apparent to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present application, some technical features well known in the art are not described.

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

[0027] In order to thoroughly understand the present application, a detailed structure will be proposed in the following description to illustrate the technical solution proposed by the present application. The optional embodiments of the present application are described in detail as follows, but in addition to these detailed descriptions, the present application may also have other implementation methods.

[0028] In conjunction with the accompanying drawings, some embodiments of the present application are described in detail below. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0029] In the production process of chips or panels, laser annealing usually uses a high-energy-density laser beam to irradiate the surface of the semiconductor film layer, rapidly heating the irradiated area in a very short time, melting the material of the semiconductor film layer and then crystallizing it, thereby achieving the purpose of crystallization. Figure 1 In the prior art, the irradiation area of ​​the light source 10 of the laser beam used for annealing on the substrate is rectangular. The annealing process includes repeated actions: after statically irradiating an area on the film layer, stop irradiating and move a preset step length along the scanning direction, and at least two adjacent irradiated areas overlap. In order to make the surface of the semiconductor material heated evenly, the ideal state is that the energy density distribution of the laser beam is uniform. However, the optical path system in the related art cannot achieve completely uniform energy density distribution of the laser beam. For example, in the scanning direction, the energy density distribution is similar to a trapezoid, with slopes on both sides, such as Figure 2(a)-2(d) Specifically, the laser beam scanning process in the related art includes: first, as shown in FIG2(a), the area between the α position and the β position receives a laser beam uniform area and a slope area irradiated once; then, the second irradiation and the third irradiation, as shown in FIG2(a), Figure 2(b)-2(c) As shown in FIG. 2( d ), the area between the α position and the β position receives one irradiation of the laser beam uniform area; in the fourth irradiation, as shown in FIG. 2( d ), the area between the α position and the β position receives one irradiation of the laser beam uniform area and one irradiation of the slope area. Since the slope areas in the first irradiation and the fourth irradiation can only partially overlap or not overlap, the amorphous silicon in the area between the α position and the β position in the related art is heated unevenly.

[0030] In order to make the laser annealing uniform, the present application provides a laser annealing method, see Figure 1 , Figure 3 as well as Figure 4 As shown, the laser annealing method includes:

[0031] Step S110: providing a substrate.

[0032] For example, the surface of the substrate includes a semiconductor material, and the semiconductor material may include amorphous silicon. However, the present invention is not limited thereto, and the substrate may also be a semiconductor substrate after an ion implantation process is performed, depending on the specific situation.

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

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

[0035] Among them, scanning a line on the substrate with a laser beam includes a periodic action, and the periodic action includes the laser beam irradiating the substrate relatively still with the substrate, the laser beam stops irradiating, and the light source of the laser beam and the substrate move relative to each other along the line direction; the irradiation area of ​​the laser beam on the substrate is a rectangle, and in the line 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, and the irradiation area of ​​the laser beam on the substrate includes a first slope area, a uniform area, and a second slope area corresponding to the isosceles trapezoid; scanning a line on the substrate with the laser beam includes that the first slope area in one periodic action overlaps with the second slope area in another periodic action.

[0036] As an example, the light source may be an excimer laser, which may include elements such as a microlens array, a Fourier lens, a reflector, and an aperture, which can focus and shape the laser beam and control the distribution of laser energy. Exemplarily, when the incident light is irradiated to the microlens array, the incident microlens array can be regarded as a multiple light source array, and the image of each microlens unit, i.e., the light source array unit, will be superimposed on the same position of the beam-uniform plane after passing through the Fourier lens. Since the image contour of the light source array unit is consistent with the pupil contour of the microlens unit, the image contour (i.e., the spot shape) on the beam-uniform plane after superposition will also be consistent with the pupil contour of the microlens unit. It should be noted that different shapes of spots can be obtained according to the hole 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, Figure 4 As shown, the horizontal axis direction is both the row direction, the X direction, and the scanning direction. The beam profile of the laser beam is an isosceles trapezoid. The irradiation area of ​​the laser beam on the substrate includes a first slope area, a uniform area, and a second slope area sequentially located in the row direction. In one embodiment, the width ratio of the first slope area, the uniform area, and the second slope area in the row direction can be achieved by adjusting the optical path of the light source, such as adjusting components such as a microlens array, a Fourier lens, a reflector, and an aperture.

[0038] It should be noted that if Figure 5 As shown, when the first slope region and the second slope region completely overlap, the sum of the two laser energies is the same at any position in the overlapping region. For example, the energy in the first slope region corresponding to the x position is h1, and the energy in the second slope region corresponding to the x position is h2, and the sum of h1 and h2 is H. Therefore, the first slope region in one cycle action is overlapped with the second slope region in another cycle action, that is, completely overlapped, so that the laser energy received at any position in the entire scanning line area is uniform, so that the amorphous silicon on the semiconductor device can be uniformly crystallized.

[0039] It can be understood that the larger the width of the first slope region and the second slope region, the easier it is to achieve the overlap of the first slope region in one cycle action with the second slope region in another cycle action, and the lower 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 first slope region or the second slope region.

[0040] The laser annealing method of the embodiment of the present application adjusts the overlapping range of the irradiation area of ​​the laser beam so that the laser heat can be evenly transferred to the semiconductor device during laser annealing, thereby making the amorphous silicon on the semiconductor device crystallize evenly.

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

[0042] Next, the laser annealing process of the present application is described by taking the area between the α position and the β position being irradiated four times in one cycle as an example, see FIG6 : For the first irradiation, as shown in FIG6 (a), the area between the α position and the β position receives one complete irradiation of the first slope area; for the second irradiation and the third irradiation, as shown in FIG6 (b), the area between the α position and the β position receives one complete irradiation of the first slope area; Figure 6(b)-6(c) As shown in FIG6( d ), the area between the α position and the β position receives a laser beam uniform area irradiation; the fourth irradiation, as shown in FIG6( d ), the area between the α position and the β position receives a complete second slope area irradiation. Thus, the irradiation of the first slope area and the irradiation of the second slope area received by the area between the α position and the β position are completely overlapped, and the laser energy received at any position in the area between the α position and the β position is uniform, so that the amorphous silicon on the semiconductor device can be uniformly crystallized.

[0043] As an example, the preset step length can be precisely controlled by the control system of the laser annealing equipment, and the control system can automatically calculate and adjust the relative movement distance between the light source of the laser beam and the substrate according to the preset parameters. The preset step length can also be determined by manual input.

[0044] In some embodiments, the light source and the substrate move relative to each other along the row direction, including: the light source is stationary and the substrate moves along the row direction, but is not limited thereto.

[0045] As an example, the relative movement of the light source and the substrate along the row direction may also include: the substrate is stationary, and the light source moves along the row direction. Specifically, which part of the light source and the substrate moves may depend on the specific situation.

[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 according to 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 a 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 length according to an annealing temperature.

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

[0051] In this embodiment, by adjusting the preset step length, the heating efficiency can be optimized, the effect of laser annealing can be ensured, and the stability of the overall process can be improved.

[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 reduced.

[0054] In this embodiment, by adjusting the width of the rectangle in the row direction, it is convenient 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 which the laser irradiates the substrate in the cycle 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 the laser annealing process can be accurately controlled, so as to achieve a preset annealing effect.

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

[0058] In this embodiment, the ratio of the width of the uniform area and the irradiated area in the row direction is adjusted so that the first slope area and the second slope area in the irradiated area can be easily and completely overlapped, thereby improving the annealing uniformity, reducing the scrap rate caused by the large overlap difference between the first slope area and the second slope area, and improving the product yield.

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

[0060] The present application also provides a semiconductor device, including a semiconductor device prepared by the above-mentioned laser annealing method.

[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 having the above semiconductor device, for example: a mobile phone motherboard having the integrated circuit, etc.

[0062] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application to this. Those of ordinary skill in the art may make various changes and modifications therein without departing from the scope and spirit of the present application. All these changes and modifications are intended to be included within the scope of the present application as required by the appended claims.

[0063] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example 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 performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be 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 only schematic, for example, the division of the units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed.

[0065] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0066] Similarly, it should be understood that in order to streamline the present application and help understand one or more of the various application aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the present application should not be interpreted as reflecting the following intention: the claimed application requires more features than the features clearly stated in each claim. More specifically, as reflected in the corresponding claims, the inventive point is that the corresponding technical problem can be solved with features less than all the features of a single disclosed embodiment. Therefore, the claims following the specific embodiment are hereby explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present application.

[0067] It will be understood by those skilled in the art that, except for mutually exclusive features, all features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed in this specification may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature that provides the same, equivalent or similar purpose.

[0068] In addition, those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments may be used in any combination.

[0069] The various component embodiments of the present application can be implemented in hardware, or in software modules running on one or more processors, or in a combination thereof. It should be understood by those skilled in the art that a microprocessor or digital signal processor (DSP) can be used in practice to implement some or all functions of some modules according to the embodiments of the present application. The application can also be implemented as a device program (e.g., computer program and computer program product) for executing a part or all of the methods described herein. Such a program implementing the present application can be stored on a computer-readable medium, or can have the form of one or more signals. Such a signal can be downloaded from an Internet website, or provided on a carrier signal, or provided in any other form.

[0070] It should be noted that the above embodiments illustrate the present application rather than limit the present application, and that those skilled in the art may design alternative embodiments without departing from the scope of the appended claims. In the claims, any reference symbol between brackets should not be constructed as a limitation to the claims. The word "comprising" does not exclude the presence of elements or steps not listed in the claims. The word "one" or "an" preceding an element does not exclude the presence of multiple such elements. The present application may be implemented by means of hardware including several different elements and by means of a suitably programmed computer. In a unit claim that lists several devices, several of these devices may be embodied by the same hardware item. The use of the words first, second, and third, etc. does not indicate any order. These words may be interpreted as names.

[0071] The above is only a specific implementation or description of a specific implementation of the present application, and the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. The protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A laser annealing method, characterized in that: The method comprises: providing a substrate; Scanning at least one line on the substrate with a laser beam, wherein scanning a line on the substrate with the laser beam includes a periodic action, wherein the periodic action includes irradiating the substrate with the laser beam relatively stationary and the laser beam stops irradiating, and the light source of the laser beam and the substrate move relative to each other along the line direction; wherein, The irradiation area of ​​the laser beam on the substrate is a rectangle, the width of the rectangle in the row direction is smaller than the width of the substrate, and the energy density distribution of the laser beam is an isosceles trapezoid, and the irradiation area of ​​the laser beam on the substrate includes a first slope area, a uniform area, and a second slope area corresponding to the isosceles trapezoid; Scanning a line of the laser beam on the substrate includes that the first slope area in one cycle action overlaps with the second slope area in another cycle action.

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

3. The laser annealing method according to claim 1, characterized in that: The light source and the substrate move relative to each other along a row direction, comprising: The light source is stationary, and the substrate moves along a row direction.

4. The laser annealing method according to claim 1, characterized in that: The substrate surface includes a semiconductor material.

5. The laser annealing method according to claim 4, characterized in that: The semiconductor material includes amorphous silicon.

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

7. The laser annealing method according to 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 according to 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 according to claim 1, characterized in that: The method further includes adjusting a ratio between widths of the uniform area and the irradiated area in the row direction.

10. A semiconductor device, characterized in that: include: A semiconductor device manufactured by the laser annealing method as claimed in any one of claims 1 to 9.

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