Laser vacuum annealing device

Abstract

The utility model provides a kind of laser vacuum annealing device, including first vacuum cavity, the bearing table of being housed in the first vacuum cavity;The first vacuum cavity is provided with the window that laser beam can pass through;The first vacuum cavity is communicated with the second vacuum cavity of housing mechanical arm, and mechanical arm is configured to carry the wafer of at least one wafer elevator to the bearing table.The laser vacuum annealing device of the utility model increases vacuum cavity, eliminates oxygen element in annealing process process, realizes complete oxygen-free in silicide formation process;Meanwhile, the wafer warping information before annealing is obtained by automatic focusing assembly and the focusing depth of laser annealing is accurately adjusted according to the above information of wafer, reduces the peeling of annealing layer caused by annealing, reduces the risk of semiconductor device performance decline caused thereby.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor processing equipment, and more specifically, to a laser vacuum annealing device. Background Technology

[0002] Laser annealing, as one of the core processes in power semiconductor manufacturing, demonstrates significant advantages in the preparation of ohmic contact layers on the back side of silicon carbide (SiC) devices, offering high efficiency and precision, and is particularly suitable for manufacturing advanced, heat-sensitive devices. However, existing laser annealing equipment generally employs a platform-moving or laser-mirror-platform composite design, with the process environment typically being non-vacuum conditions under atmospheric pressure or inert gas protection. This design, when dealing with the processing requirements of large-size, highly warped thin wafers, exposes two key defects that severely restrict the quality of the ohmic contact layer and the reliability of the device.

[0003] First, there are challenges in adsorption stability and thermal conduction control of thin wafers in non-vacuum environments. For thin wafers with small thickness and warping, traditional equipment relies on mechanical clamping or electrostatic adsorption to fix the wafer. However, in non-vacuum environments, the residual air layer between the wafer and the stage leads to uneven distribution of adsorption forces, and localized differences in laser energy absorption due to fluctuations in contact thermal resistance. Specifically, during laser scanning, the warped wafer undergoes micron-level displacement with the stage when it expands due to heat, causing the temperature field in the annealing area to deviate from the design value, resulting in uneven resistivity distribution in the ohmic contact layer. The instability of the thermal conduction path further exacerbates wafer warping, forming a vicious cycle of "thermal-mechanical coupling," ultimately causing microcracks or delamination defects at the interface between the metal layer and the SiC substrate. Although existing technologies attempt to alleviate these problems by optimizing the adsorption structure or introducing dynamic compensation algorithms, the uncontrollability of the air film under non-vacuum conditions still makes it difficult to overcome physical limits in process stability.

[0004] Second, there is the issue of oxygen doping and interface failure in the silicide layer induced by the atmospheric environment. During laser annealing, the high-temperature reaction between the Ti / Ni-Si metal system and the SiC substrate is extremely sensitive to oxygen contamination. In a non-vacuum environment, oxygen penetrates the silicide layer through two pathways: gas-phase diffusion, where atmospheric oxygen molecules (O2) dissociate into active oxygen atoms in the high-temperature laser region and rapidly diffuse along grain boundaries or defects to the metal-SiC interface; and surface adsorption, where oxygen atoms adsorb onto the surface of the molten metal layer and form Ti / Ni through solid solution or oxidation reactions. x Si x O x Composite oxides. Oxygen doping induces multiple material property degradations, such as electrical performance degradation, and the transition from the low-resistivity TiSi2 / NiSi phase to the high-resistivity TiO2 phase. x Si yThe transformation leads to increased contact resistivity; mechanical property mismatch, with the Young's modulus of the silicide layer fluctuating by 2-3 GPa, and the thermal expansion coefficient (CTE) differing more from that of the SiC substrate, resulting in residual tensile stress at the interface; and attenuation of the interface bonding strength. When the residual stress exceeds the critical bonding strength between the Ag metal layer and the SiC substrate, metal layer peeling occurs, manifesting as edge lifting or large-area peeling, resulting in a significant decrease in device yield.

[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this utility model, and therefore may include information that does not constitute prior art known to those skilled in the art. Utility Model Content

[0006] To address the problems in the existing technology, the purpose of this utility model is to provide a laser vacuum annealing device. This annealing device adds a vacuum cavity to eliminate oxygen (O) elements during the annealing process, achieving a completely oxygen-free process during silicide formation, thereby improving the performance of related semiconductor devices prepared using laser annealing technology.

[0007] This utility model provides a laser vacuum annealing device, including a first vacuum chamber and a support stage housed in the first vacuum chamber;

[0008] The first vacuum cavity is provided with a window through which a laser beam can pass;

[0009] The first vacuum chamber is connected to a second vacuum chamber housing a robotic arm, which is configured to transport wafers from at least one wafer lift to the support platform.

[0010] According to some examples of the present invention, the laser vacuum annealing apparatus further includes a first position calibration component;

[0011] The first position calibration component is configured to correct the position of the wafer during the process of transporting the wafer from at least one of the wafer elevators to the carrier stage.

[0012] According to some examples of the present invention, the laser vacuum annealing apparatus further includes a second position calibration component;

[0013] The second position calibration component is configured to correct the position of the wafer during the process of transporting the wafer from the carrier stage to the stage of the next process.

[0014] According to some examples of the present invention, the laser vacuum annealing device further includes a drive assembly connected to the robotic arm;

[0015] The moving end of the drive component is connected to one end of the robotic arm and drives the robotic arm to translate and / or drives the other end of the robotic arm to rotate relative to the connecting end of the robotic arm.

[0016] According to some examples of this utility model, the robotic arm is a grooved conveyor arm.

[0017] According to some examples of the present invention, the laser vacuum annealing apparatus further includes a laser assembly and a triaxial galvanometer system disposed between the laser assembly and the wafer, the triaxial galvanometer system being configured to adjust the focusing position and focusing depth of the laser beam emitted by the laser assembly.

[0018] According to some examples of the present invention, the laser vacuum annealing apparatus further includes an autofocusing component housed within the first vacuum cavity;

[0019] The autofocus component is configured to scan the annealing surface of the wafer carried by the stage and obtain warpage information of the annealing surface of the wafer.

[0020] According to some examples of this utility model, the laser vacuum annealing device further includes a computing module;

[0021] The calculation module is communicatively connected to the control unit of the autofocus component. The calculation module is configured to receive warpage information obtained by the autofocus component and calculate the focus depth information of the surface to be annealed based on the warpage information.

[0022] According to some examples of this utility model, the laser vacuum annealing device also includes a control module;

[0023] The control module is communicatively connected to the computing module. The control module is configured to receive the focusing depth information from the computing module and control the triaxial galvanometer system to adjust the focusing position and focusing depth of the laser beam based on the focusing depth information.

[0024] The laser vacuum annealing device of this invention adds a vacuum cavity to eliminate oxygen (O) during the annealing process, achieving a completely oxygen-free process during silicide formation. At the same time, it obtains wafer warpage information before annealing through an automatic focusing component and precisely adjusts the focusing depth during laser annealing based on the above information, reducing the risk of annealing layer peeling caused by annealing and thus reducing the risk of semiconductor device performance degradation. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. Other features, objects, and advantages of this invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings. It is obvious that the drawings described below are merely some embodiments of this invention, and those skilled in the art can obtain other drawings based on these drawings without inventive effort. Furthermore, the drawings are merely illustrative diagrams of this disclosure and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore, repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities.

[0026] Figure 1 This is a top view of a laser vacuum annealing apparatus according to an embodiment of the present invention;

[0027] Figure 2 This is a cross-sectional view of a laser vacuum annealing apparatus according to an embodiment of the present invention;

[0028] Figure 3 The image shows the warpage curve of the annealing surface of a wafer and the fitted focusing depth curve obtained by the autofocusing component of an embodiment of the present invention. Detailed Implementation

[0029] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, they are provided so that this disclosure will be more comprehensive and complete, and will fully convey the concept of the exemplary embodiments to those skilled in the art. The described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0030] In this specification, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics represented in connection with that embodiment or example, which are included in at least one embodiment or example of this specification. Furthermore, the specific features, structures, materials, or characteristics represented may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples represented in this specification, as well as the features of different embodiments or examples.

[0031] Throughout this specification, when it is said that a device is "connected" to another device, this includes not only "direct connection" but also "indirect connection" by placing other components in between. Terms indicating relative space, such as "front," "back," "up," and "down," are used to more easily explain the relationship of one device relative to another illustrated in the figures. These terms refer not only to their meaning in the figures but also to other meanings or operations of the device in use. For example, if the device in the figures is flipped, a device previously described as "below" another device may now be described as "above" another device. Therefore, the exemplary term "down" includes both "up" and "below." The device may be rotated 90° or other angles, and the terms representing relative space are interpreted accordingly.

[0032] Although the terms first, second, etc., are used in some instances herein to refer to various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, first interface and second interface, etc., are used. Furthermore, as used herein, the singular forms “a,” “an,” and “the” are intended to also include the plural forms unless the context indicates otherwise. It should be further understood that the terms “comprising,” “including,” indicate the presence of the stated feature, step, operation, element, component, item, kind, and / or group, but do not exclude the presence, occurrence, or addition of one or more other features, steps, operations, elements, components, items, kinds, and / or groups. The terms “or” and “and / or” as used herein are interpreted as inclusive, or mean any one or any combination thereof. Thus, “A, B, or C” or “A, B, and / or C” means “any one of the following: A; B; C; A and B; A and C; B and C; A, B, and C.” Exceptions to this definition will only occur if the combination of elements, functions, steps, or operations is inherently mutually exclusive in some way.

[0033] Although not fully defined, all terms, including technical and scientific terms used herein, shall have the same meaning as commonly understood by one of ordinary skill in the art to which this specification pertains. Terms defined in commonly used dictionaries shall be further interpreted as having a meaning consistent with the relevant technical literature and the content of this present instruction, and shall not be over-interpreted as having an ideal or overly formulaic meaning unless otherwise defined.

[0034] The structure of the laser vacuum annealing device of this utility model is further described below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments are not intended to limit the scope of protection of this utility model.

[0035] This invention provides a laser vacuum annealing device. Figure 1 and Figure 2The images shown are a top view and a cross-sectional view of a laser vacuum annealing apparatus according to an embodiment of the present invention. The laser vacuum annealing apparatus includes a first vacuum chamber 91 and a support platform 3 housed within the first vacuum chamber 91. The first vacuum chamber 91 is connected to a second vacuum chamber 92 housing a robotic arm 2. The second vacuum chamber 92 typically has multiple connection ports for wafer lifting machines. Figure 1 The system is equipped with three wafer elevators: wafer elevator 1a, wafer elevator 1b, and wafer elevator 1c. These elevators hold wafers awaiting annealing. The first vacuum chamber 91 and the second vacuum chamber 92 can be connected and disconnected via a gate valve 911. When the gate valve 911 is open, a robotic arm 2 can transport a wafer from at least one wafer elevator to a support platform 3. After the support platform 3 holds the wafer W, the gate valve 911 can be closed to maintain a higher vacuum level in the first vacuum chamber 91 where the wafer is annealed. The support platform 3 can be a vacuum chuck connected to a vacuum pumping device 31.

[0036] The laser vacuum annealing apparatus also includes a laser assembly 8. The first vacuum chamber 91 is provided with a window 912 through which the laser beam emitted by the laser assembly 8 can pass. The laser beam passes through the window 912 and anneals the surface of the wafer W to be annealed on the support stage 3. The scanning position of the laser beam must be able to cover the entire wafer W.

[0037] Furthermore, the laser vacuum annealing apparatus also includes a triaxial galvanometer system (not shown in the figure) between the laser assembly 8 and the wafer W. The triaxial galvanometer system is used to adjust the focusing position and focusing depth of the laser beam emitted by the laser assembly 8.

[0038] Compared to existing nitrogen-filled (oxygen content ~10ppm) laser annealing, the laser vacuum annealing device of this invention can efficiently isolate O element (oxygen content can be reduced to 0.002-0.01ppm according to the vacuum value) during annealing, ensuring that the functional layer formed by annealing (especially the functional layer is silicide) can have good ohmic contact and back-gold robustness.

[0039] In some embodiments, the laser vacuum annealing apparatus further includes a drive assembly 23 connected to a robotic arm. The moving end of the drive assembly 23 is connected to one end (connection end 21) of the robotic arm 2. The drive assembly 23 may include a translation drive unit and a rotation drive unit, such as... Figure 1As shown, the translation drive unit drives the connecting end 21 and the clamping end 22 of the robotic arm 2 to move, so that the position of the clamping end 22 corresponds to one of the multiple wafer lifts to pick up a wafer. Furthermore, the laser vacuum annealing apparatus may also include a first position calibration component 51. The first position calibration component 51 may be disposed in a cavity 93 connected to the second vacuum cavity 92. The first position calibration component 51 is configured to correct the position of the wafer during the process of transporting the wafer from at least one wafer lifter to the carrier stage. That is, after the gripping end 22 of the robotic arm 2 picks up a wafer, the rotation drive unit drives the gripping end 22 to rotate in a circle with the connecting end 21 as the center, rotating it to the carrier stage of the first position calibration component 51. The position of the wafer is calibrated (rotated) by the first position calibration component 51, so that after the gripping end 22 of the robotic arm 2 grips the wafer again and transports it to the carrier stage 3 for placement, the position of the wafer (including the origin of the wafer, the starting point of the annealing sweep, the arrangement of the semiconductor device array on the wafer, etc.) can be directly applied to the laser annealing process without the need for calibration.

[0040] In embodiments where the wafer is a thin sheet, the robotic arm can be a grooved transfer arm, that is, the gripping end 22 of the robotic arm 2 is grooved, and the groove of the gripping end 22 is adapted to the size of the wafer (such as curvature), thereby increasing the contact between the gripping end 22 and the edge of the wafer, increasing the stability during the wafer transfer process, and preventing the wafer from shifting or even falling off.

[0041] In some embodiments, the laser vacuum annealing apparatus further includes an autofocusing assembly 4 housed within a first vacuum chamber 91. The autofocusing assembly 4 is configured to scan the surface of the wafer to be annealed, which is supported by a stage, and obtain warpage information of the surface to be annealed. The autofocusing assembly 4 typically includes a lens 41, a drive motor for moving the lens assembly, sensors, and a control unit. The control unit controls the drive motor to enable the lens 41 to scan various positions on the wafer surface. Based on the information from the sensors when scanning each position, the surface information corresponding to each position is determined. Therefore, the aforementioned warpage information is a data set including the coordinates of each position on the surface to be annealed of the wafer and the corresponding warpage value for each position.

[0042] Furthermore, the laser vacuum annealing apparatus also includes a calculation module; the calculation module is configured to receive warpage information from the autofocus assembly and calculate the focusing depth information of the surface to be annealed based on the warpage information.

[0043] The laser vacuum annealing apparatus also includes a control module and a calculation module that are communicatively connected to the control unit of the autofocus component. The calculation module is used to receive the warp information of the autofocus component and calculate the focus depth information of the surface to be annealed based on the warp information. Accordingly, the focus depth information is a data set that includes the coordinates (focus positions) of each position on the surface to be annealed of the wafer and the focus depth value corresponding to each position.

[0044] The laser vacuum annealing apparatus may also include a control module, which is communicatively connected to the computing module. The control module is configured to receive the focusing depth information from the computing module and control the triaxial galvanometer system to adjust the focusing position and focusing depth of the laser beam based on the focusing depth information.

[0045] When using the laser vacuum annealing apparatus of this invention, the wafer is placed on the support stage 3 by a robotic arm. Before performing laser annealing, the autofocus component 4 collects the warp information of the surface of the wafer to be annealed. The calculation module receives the warp information from the autofocus component and calculates the focus depth information of the surface to be annealed based on the warp information. Figure 3 This diagram illustrates the warpage curve (solid line) and the fitted focus depth curve (curve) of a wafer's surface to be annealed, obtained by an autofocusing component according to an embodiment of this invention. The focus depth information can be warpage information or a fit to the warpage curve of the wafer's surface to be annealed, such as a smooth fit. Laser annealing uses the focus depth information to control the three-axis galvanometer system to adjust the focusing position and depth of the laser beam to perform annealing. The scanning method during laser annealing is adapted to the lens scanning method of the autofocusing component, such as both using XY galvanometer scanning. In the above steps, the autofocusing component characterizes the warpage information formed by the wafer's thinness during annealing, and then, based on the actual structure (warpage information) of the wafer's surface to be annealed, the focus depth during annealing is controlled more precisely. This is particularly suitable for annealing silicides (such as NiSi) containing elements sensitive to focus depth.

[0046] During laser annealing, the wafer releases stress, causing a change in its warping. Typically, when the back side is facing up, the warping shape changes from convex to concave. To more accurately calibrate the position of the wafer W, the laser vacuum annealing apparatus also includes a second position calibration component 52. The second position calibration component 52 can be disposed in a cavity 94 connected to a second vacuum cavity 92. The second position calibration component is configured to correct the wafer position during the process of transporting the wafer W from the carrier stage 3 to the stage of the next process. Specifically, after laser annealing of the wafer, the gripping end 22 of the robotic arm 2 picks up the wafer W from the carrier stage 3. The rotation drive unit drives the gripping end 22 to rotate in a circle with the connecting end 21 as the axis, rotating it to the stage of the second position calibration component 52. The second position calibration component 52 calibrates (rotates) the wafer position in preparation for the next process.

[0047] In summary, the laser vacuum annealing device of this invention can effectively prevent the interference of oxygen elements during the laser annealing process, thereby greatly improving the robustness of the back metal layer. At the same time, the relatively in-situ analysis method can also help the industry better understand the laser annealing process and promote scientific research and industrial development.

[0048] It should be noted that in the technical solution of the laser vacuum annealing device of this utility model, each functional module and module unit can correspond to a specific hardware circuit in the integrated circuit structure. Therefore, it only involves the improvement of the specific hardware circuit. The hardware part is not merely a carrier for executing control software or computer programs. Therefore, solving the corresponding technical problem and obtaining the corresponding technical effect does not involve the application of any control software or computer programs. In other words, this utility model can solve the technical problem and obtain the corresponding technical effect by simply using the improvements in the hardware circuit structure involved in these modules and units, without the need for specific control software or computer programs to achieve the corresponding function.

[0049] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention and should not be construed as limiting the specific implementation of the present invention to these descriptions. It will be apparent to those skilled in the art that this application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be embraced within this application. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A laser vacuum annealing apparatus, characterized in that, Includes a first vacuum chamber and a support stage housed within the first vacuum chamber; The first vacuum cavity is provided with a window through which a laser beam can pass; The first vacuum chamber is connected to a second vacuum chamber housing a robotic arm, which is configured to transport wafers from at least one wafer lift to the support platform.

2. The laser vacuum annealing apparatus according to claim 1, characterized in that, It also includes a first position calibration component; The first position calibration component is configured to correct the position of the wafer during the process of transporting the wafer from at least one of the wafer elevators to the carrier stage.

3. The laser vacuum annealing apparatus according to claim 1, characterized in that, It also includes a second position calibration component; The second position calibration component is configured to correct the position of the wafer during the process of transporting the wafer from the carrier stage to the stage of the next process.

4. The laser vacuum annealing apparatus according to claim 1, characterized in that, It also includes a drive assembly connected to the robotic arm; The moving end of the drive component is connected to one end of the robotic arm and drives the robotic arm to translate and / or drives the other end of the robotic arm to rotate relative to the connecting end of the robotic arm.

5. The laser vacuum annealing apparatus according to claim 1, characterized in that, The robotic arm is a grooved conveyor arm.

6. The laser vacuum annealing apparatus according to claim 1, characterized in that, It also includes a laser assembly and a triaxial galvanometer system disposed between the laser assembly and the wafer, the triaxial galvanometer system being configured to adjust the focusing position and focusing depth of the laser beam emitted by the laser assembly.

7. The laser vacuum annealing apparatus according to claim 6, characterized in that, It also includes an autofocusing assembly housed within the first vacuum chamber; The autofocus component is configured to scan the annealing surface of the wafer carried by the stage and obtain warpage information of the annealing surface of the wafer.

8. The laser vacuum annealing apparatus according to claim 7, characterized in that, It also includes a computing module; The calculation module is communicatively connected to the control unit of the autofocus component. The calculation module is configured to receive warpage information obtained by the autofocus component and calculate the focus depth information of the surface to be annealed based on the warpage information.

9. The laser vacuum annealing apparatus according to claim 8, characterized in that, It also includes a control module; The control module is communicatively connected to the computing module. The control module is configured to receive the focusing depth information from the computing module and control the triaxial galvanometer system to adjust the focusing position and focusing depth of the laser beam based on the focusing depth information.

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