Pseudo-wafer and thin film vapor deposition apparatus

Abstract

This application provides a dummy wafer and a thin film vapor deposition apparatus. The dummy wafer for thin film vapor deposition includes: a first surface pattern located on the surface of the dummy wafer and close to the wafer center of the dummy wafer; and a second surface pattern located on the surface of the dummy wafer and between the first surface pattern and the wafer edge of the dummy wafer. The vertical cross-sectional shape of the first surface pattern is different from that of the second surface pattern to form an adsorption force gradient distributed radially along the dummy wafer, thereby improving the uniformity of thin film deposition thickness within the same wafer and reducing the current difference between the drain-source current of the die located at the wafer center and the drain-source current of the die located at the wafer edge within the same wafer.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, and in particular to a dummy wafer and thin film vapor deposition apparatus. Background Technology

[0002] In semiconductor manufacturing, furnace tube processing is a crucial process for batch processing of wafers, primarily used in thermal oxidation, thermal annealing, thermal baking, and chemical vapor deposition (CVD) processes. In CVD, furnace tube processing allows for the deposition of thin films on wafers. Typically, the wafer is first placed along the axis of a wafer boat within a wafer boat, which is then placed inside the furnace tube. Conditions are then applied to the furnace tube, such as heating and the introduction of process gases, to deposit the thin film.

[0003] The heating device in a furnace tube typically includes a first heating element extending along the tube's axial direction and a second heating element located at the tube's ends. Temperature control can be achieved in different areas within the furnace tube by adjusting the heating elements. However, for the central region (center) within the furnace tube, since this region is only equipped with a single temperature controller (TC) for the first heating element, its temperature regulation capability is limited by the physical layout and thermal conductivity characteristics of the first heating element. This makes it difficult to optimize the uniformity of thin film deposition within the same wafer (WiW) within the furnace tube (especially in the central region) using traditional temperature control methods. Utility Model Content

[0004] In view of the above problems, there is a need to propose a dummy wafer and thin film vapor deposition equipment, which aims to improve the uniformity of thin film deposition thickness within the same wafer.

[0005] According to a first aspect of the embodiments of this application, a dummy wafer for thin film vapor deposition is provided, comprising:

[0006] A first surface pattern is located on the surface of the dummy wafer and near the wafer center of the dummy wafer; and

[0007] The second surface pattern is located on the surface of the dummy wafer and between the first surface pattern and the wafer edge of the dummy wafer.

[0008] The vertical cross-sectional shape of the first surface pattern is different from that of the second surface pattern to form an adsorption force gradient distributed radially along the pseudo-wafer.

[0009] Optionally, each of the first surface pattern and the second surface pattern is a groove having a predetermined vertical cross-sectional shape.

[0010] Optionally, the predetermined vertical cross-sectional shape includes one of the following shapes: rectangle, trapezoid, triangle.

[0011] Optionally, the dummy wafer further includes a third surface pattern located on the surface of the dummy wafer and between the first surface pattern and the second surface pattern, wherein the third surface pattern has a different vertical cross-sectional shape from the first surface pattern and the second surface pattern.

[0012] Optionally, the vertical cross-sectional shapes of the first surface pattern, the second surface pattern, and the third surface pattern are rectangle, triangle, and trapezoid, respectively.

[0013] According to a second aspect of the embodiments of this application, a thin film vapor deposition apparatus is provided, comprising:

[0014] tube body;

[0015] A crystal boat, located inside the tube, is used to hold multiple product wafers;

[0016] A heating device, located within the tube, includes a first heating element extending axially along the tube body and a second heating element located at an end of the tube body; and

[0017] The dummy wafer described above is located within the boat and adjacent to the plurality of product wafers.

[0018] Optionally, the dummy wafer is located above and / or below the plurality of product wafers.

[0019] Optionally, the dummy wafer is also located between two adjacent product wafers.

[0020] Optionally, the larger the surface area of ​​the surface pattern on the dummy wafer surface used to adjust the adsorption force on the process gas, the stronger the adsorption force on the process gas.

[0021] Optionally, along the radial direction of the dummy wafer, the closer to the wafer center of the dummy wafer, the stronger the adsorption force of the surface pattern on the process gas.

[0022] One of the above technical solutions has the following unexpected technical effect:

[0023] By constructing a three-dimensional patterned structure with a radial adsorption force gradient on the surface of a blank wafer, the technical bottleneck of traditional furnace tube processes, which rely solely on temperature controllers to adjust the uniformity of thin film deposition, is overcome. When process gases flow within the reaction chamber, various surface patterns on the dummy wafer surface form combinations of grooves with different vertical cross-sectional shapes, creating a continuously gradually changing adsorption force gradient curve distributed radially along the dummy wafer. By utilizing the differences in the adsorption capacity of process gas molecules by surface patterns in different regions, the gas flow field distribution can be controlled. This allows for the active adjustment of thin film deposition uniformity within the same wafer (especially in the central region of the furnace tube), which is normally limited by thermal conductivity, through hydrodynamic effects. This improves the uniformity of thin film deposition thickness within the same wafer, thereby reducing the current difference between the drain-source current of dies located at the wafer center and those located at the wafer edge.

[0024] Furthermore, by placing dummy wafers above, below, or between adjacent wafers in the crystal boat, the adsorption force gradient distributed radially along the dummy wafer can work synergistically with the heating compensation gradient along the furnace tube axis, thereby improving the uniformity of thin film deposition thickness within the same wafer. This reduces the current difference between the drain-source current of the die located at the center of the wafer and the drain-source current of the die located at the edge of the wafer.

[0025] It should be noted that the above general description and the following detailed description are merely exemplary and explanatory and do not limit this application. Attached Figure Description

[0026] The above and other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0027] Figure 1 A schematic diagram showing the distribution of thin film deposition thickness on a product wafer in related technologies is presented;

[0028] Figure 2 This diagram illustrates the electrical distribution of the die within the product wafer in the relevant technology.

[0029] Figure 3 It shows Figure 2 Box plot in the middle;

[0030] Figure 4 A schematic diagram of the thin film vapor deposition apparatus in an embodiment of this application is shown;

[0031] Figure 5 This illustration shows a schematic diagram of the gas flow field of the process gas near the surface of a blank wafer in an embodiment of this application;

[0032] Figure 6 This illustration shows a schematic diagram of the gas flow field of the process gas near the surface of the dummy wafer in an embodiment of this application.

[0033] Figure 7 A schematic diagram of the structure of the dummy wafer in an embodiment of this application is shown;

[0034] Figure 8 This illustration shows a schematic diagram of the arrangement of product wafers and dummy wafers in a wafer boat according to one embodiment of this application;

[0035] Figure 9 A schematic diagram of the thin film deposition thickness distribution on the product wafer according to an embodiment of this application is shown. Detailed Implementation

[0036] The present application will now be described in more detail with reference to the accompanying drawings. In the various drawings, the same elements are indicated by similar reference numerals. For clarity, the various parts in the drawings are not drawn to scale. Furthermore, some well-known parts may not be shown.

[0037] Many specific details of this application, such as the structure, materials, dimensions, processing techniques, and methods of the devices, are described below to provide a clearer understanding of the application. However, as those skilled in the art will understand, this application may be implemented without adhering to these specific details.

[0038] Furthermore, certain terms are used in this patent specification and claims to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. This patent specification and claims do not distinguish components based on differences in name, but rather on differences in function.

[0039] Furthermore, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0040] This application may be presented in various forms, some of which will be described below.

[0041] In chemical vapor deposition (CVD), the wafer is typically placed along the axis of the wafer in a boat, which is then placed into the furnace tube. Conditions are applied to the furnace tube, such as heating and the introduction of process gases, to deposit a thin film. Because the process gases are ejected through a syringe as the wafer rotates, they diffuse from the chip edge towards the center, forming films such as zirconium oxide. Therefore, the film thickness at the wafer edge is often thicker than at the center within the same wafer. To address this, temperature control is typically achieved by adjusting the heating element to regulate the temperature in different areas of the furnace tube, thereby improving the uniformity of film deposition within the same wafer.

[0042] The heating device in a furnace tube typically includes a first heating element extending axially along the tube body and a second heating element located at the end of the tube body. When the wafer is located in the end region of the wafer boat, the reaction temperature inside the furnace tube can be adjusted using the second heating element, thereby reducing the difference in thin film deposition thickness along the wafer radial direction (between the wafer edge and the wafer center) and improving the uniformity of thin film deposition thickness within the same wafer. However, when the wafer is located in the central region between the two ends of the wafer boat, since this region is only equipped with a single temperature controller—the first heating element—its temperature regulation capability is limited by the physical layout and thermal conductivity characteristics of the first heating element. This makes it difficult to optimize the uniformity of thin film deposition thickness within the same wafer inside the furnace tube (especially in the central region of the furnace tube) using traditional temperature control methods. For example, when the number of wafers is small, in the wafer boat, the wafers are arranged from the first end of the wafer boat to the central region between the two ends, leaving the area near the second end of the wafer boat empty. Due to the uneven distribution of the gas flow field, the problem of poor thin film thickness uniformity of the wafers located in the central region of the furnace tube is more severe.

[0043] Figure 1 This diagram illustrates the distribution of thin film deposition thickness on a product wafer in related technologies. For example... Figure 1 As shown, the product wafer 100 manufactured using the furnace tube process of related technologies for chemical vapor deposition is schematically divided into four regions based on the film thickness. Along the radial direction of the product wafer 100, from the wafer center to the wafer edge, these regions are 110, 120, 130, and 140. The grayscale value in each region represents the film deposition thickness; the darker the grayscale, the greater the film deposition thickness. That is, along the radial direction of the product wafer 100, from the wafer edge to the wafer center, the film deposition thickness gradually decreases, and the morphology of each region is irregular.

[0044] Figure 2 The diagram illustrates the electrical distribution of the die within the product wafer in the relevant technology. For example... Figure 2 As shown, Figure 1 The product wafer 100 is used to form multiple dies 101. Figure 2 The grayscale value represents the drain-source current Ids of the measured die 101; the darker the grayscale, the greater the current. Figure 2 It can be seen that along the radial direction of wafer 100, from the center of the wafer to the edge of the wafer, there are grayscale 201, grayscale 202 and grayscale 203, grayscale 201 is greater than grayscale 202, and grayscale 202 is greater than grayscale 203. Figure 3 It shows Figure 2 Box plot in the image. (Example) Figure 3 As shown, the horizontal axis represents different regions in the product wafer 100 from the wafer center to the wafer edge, and the vertical axis represents the drain-source current Ids of the measured die 101. The boxplot can represent the median, upper and lower quartiles, and outliers of the current values ​​in different regions. Bars 301, 302, and 303 correspond to... Figure 3 Gray levels 201, 202, and 203, along the radial direction of the product wafer 100 from the wafer center to the wafer edge, show that the closer to the wafer center, the larger the drain-source current Ids of the die 101. The current difference between the drain-source current Ids of the die 101 located at the wafer center and the drain-source current Ids of the die 101 located at the wafer edge is as high as 26%. It is understandable that the poor uniformity of thin film deposition thickness within the same wafer (WiW) causes a large current difference between the drain-source current Ids of the die located at the wafer center and the drain-source current Ids of the die located at the wafer edge.

[0045] Based on this, this application provides a dummy wafer and a thin film vapor deposition apparatus to improve the uniformity of thin film deposition thickness within the same wafer, thereby reducing the current difference between the drain-source current of the die located at the center of the wafer and the drain-source current of the die located at the edge of the wafer.

[0046] Figure 4 A schematic diagram of the thin film vapor deposition apparatus in an embodiment of this application is shown. Figure 4 As shown, the tube body of the thin film vapor deposition equipment 400 includes a crystal boat 410, an internal heating device, an air inlet pipe 430, an inner shell 441, an outer shell 442, external heaters 451 and 452, and an exhaust pipe (not shown).

[0047] The inner shell 441 serves as the reaction chamber 401. The outer shell 442 partially surrounds the inner shell 441, and the space between the outer shell 442 and the inner shell 441 serves as the second chamber 402. Internal heating devices are located in both the second chamber 402 and the reaction chamber 401. The internal heating devices include a first heating element 421 extending axially along the tube body in the central region between the ends of the furnace tubes, and a second heating element 422 located at the ends of the tubes. It should be noted that only the first heating element 421, a single temperature controller, is located in the central region between the ends of the furnace tubes, and its temperature regulation capability is limited by the physical layout and thermal conductivity characteristics of the first heating element 421. The air inlet pipe 430 communicates with the bottom of the reaction chamber 401. External heaters 451 and 452 are located at the two ends of the outer shell 442, respectively.

[0048] In the thin film deposition process of product wafers using a thin film vapor deposition (FCV) apparatus 400, the product wafer and dummy wafer are first placed along the axis of the wafer in a wafer boat 410, and then the wafer boat 410 is transported to a preset position in the reaction chamber 401. The product wafer is used to form a die, and its surface has a raised / lowered pattern formed by the device structure. The dummy wafer is used to adjust the flow field distribution of process gases within the furnace tube, and its surface has a pre-generated surface pattern. This surface pattern can be formed using photolithography and etching processes, resulting in a groove structure with a specific pattern density to produce a pattern loading effect. The larger the surface area of ​​the surface pattern, the stronger its adsorption force on the process gases. Figure 5 A schematic diagram of the gas flow field of the process gas near the surface of a blank wafer is shown in an embodiment of this application. For example... Figure 5 As shown, the arrow indicates the gas flow field of the process gas on the surface of the blank dummy wafer 500, which is a uniform flow field. Figure 6 A schematic diagram of the gas flow field of the process gas near the surface of the dummy wafer 600 is shown in an embodiment of this application. Figure 6 As shown, the arrows indicate the gas flow field of the process gas on the surface of the dummy wafer 600, converging from the wafer edge towards the surface pattern region 601. It should be noted that the pattern loading effect is a technical principle that utilizes the differences in the adsorption capacity of different regions for process gas molecules to regulate the gas flow field distribution by forming groove structures with specific geometric features on the surface of the dummy wafer. When the process gas flows within the reaction chamber 401, the surface pattern of the dummy wafer, through the local fluid resistance differences generated by its three-dimensional morphology, creates gas migration potential energy distributed radially along the dummy wafer. This physical adsorption mechanism overcomes the limitations of traditional temperature control methods, enabling the central region between the inner ends of the furnace tubes, which originally relied solely on heat conduction for regulation, to actively adjust the deposition uniformity through hydrodynamic effects.

[0049] In some embodiments, the surface pattern includes a variety of patterns with different vertical cross-sectional shapes to form an adsorption force gradient distributed radially along the pseudo-wafer. Figure 7 A schematic diagram of the dummy wafer structure in an embodiment of this application is shown. For example... Figure 7 As shown, the dummy wafer 700 includes a first surface pattern 701 and a second surface pattern 702. The first surface pattern 701 is located on the surface of the dummy wafer 700 and near its center. The second surface pattern 702 is located on the surface of the dummy wafer 700 and between the first surface pattern 701 and the edge of the dummy wafer 700. The vertical cross-sectional shape of the first surface pattern 701 is different from that of the second surface pattern 702 to form an adsorption force gradient distributed radially along the dummy wafer 700. This effect is that by creating differences in adsorption force on the surface of the dummy wafer through grooves of different cross-sectional shapes, process gases preferentially migrate to areas with stronger adsorption force in the flow field, thereby compensating for the problem of poor film deposition uniformity within the same wafer inside the furnace tube (especially in the central region of the furnace tube) caused by limitations of conventional temperature control methods. In some embodiments, the dummy wafer 700 also includes a third surface pattern 703. The third surface pattern 703 is located on the surface of the dummy wafer 700 and between the first surface pattern 701 and the second surface pattern 702. Each of the first surface pattern 701, the second surface pattern 702, and the third surface pattern 703 is a groove with a predetermined vertical cross-sectional shape. The vertical cross-sectional shapes of the first surface pattern 701, the second surface pattern 702, and the third surface pattern 703 are different. The predetermined vertical cross-sectional shape of the first surface pattern 701, the second surface pattern 702, and the third surface pattern 703 includes one selected from the following shapes: rectangle, trapezoid, and triangle. In some embodiments, the vertical cross-sectional shapes of the first surface pattern 701, the second surface pattern 702, and the third surface pattern 703 are rectangle, triangle, and trapezoid, respectively. Along the radial direction of the dummy wafer 700, the closer to the wafer center of the dummy wafer 700, the stronger the adsorption force of the surface pattern on the process gas. When the process gas diffuses from the wafer edge to the center, the adsorption gradient on the surface of the dummy wafer 700 guides the gas distribution to shift towards the wafer center, thereby balancing the difference in thin film deposition rate between the wafer center and the wafer edge of the product wafer. Furthermore, compared to simply setting the first surface pattern 701 and the second surface pattern 702, by introducing an intermediate adsorption layer with a trapezoidal cross-section (i.e., the third surface pattern 703) in the radial transition region of the dummy wafer 700, a continuously gradient adsorption force distribution curve can be formed, thereby allowing for more precise control of the radial migration path of the process gas. This three-level gradient design not only enhances the kinetic energy conversion efficiency of gas molecules in the flow direction, but also induces local vortices through the inclined structure of the trapezoidal grooves, causing the gas flow field, which originally tends to deposit towards the wafer edge, to generate a secondary diversion effect towards the wafer center.

[0050] Figure 8This diagram illustrates the arrangement of product wafers and dummy wafers in a wafer boat according to one embodiment of this application. Product wafers 810 and dummy wafers 700 are located within a wafer boat 410, with the dummy wafer 700 adjacent to multiple product wafers 810. The surface of the dummy wafer 700 has a surface pattern for adjusting the adsorption force on process gases. Figure 8 As shown, the dummy wafer 700 is located above and below multiple product wafers 810. It should be noted that the dummy wafer 700 can also be located above or below multiple product wafers 810. It should also be noted that the dummy wafer 700 can be located between two adjacent product wafers 810. Figure 9 A schematic diagram of the thin film deposition thickness distribution on a product wafer according to an embodiment of this application is shown. Figure 9 As shown, along the radial direction of product wafer 810, from the wafer center to the wafer edge, the regions are successively 910, 920, 930, and 940. Figure 9 The grayscale values ​​in each region represent the film deposition thickness; the darker the grayscale, the greater the film deposition thickness. By using the dummy wafer and thin film vapor deposition equipment of this embodiment, the adsorption force gradient distributed radially along the dummy wafer and the heating compensation gradient along the furnace tube axis work synergistically. After adjusting the process gas flow field, the film deposition thickness inside the product wafer 810 increases radially from the wafer edge to the wafer center, and the morphology of each region is relatively regular. In other words, the film thickness is uniform in regions on the product wafer 810 that are at the same distance from the wafer center. It is understood that by placing the dummy wafer 700 above, below, or between adjacent wafers of the product wafer 810, the adsorption force gradient distributed radially along the dummy wafer 700 and the heating compensation gradient along the furnace tube axis can work synergistically, improving the uniformity of film deposition thickness within the same wafer. This, in turn, reduces the current difference between the drain-source current of the die located at the wafer center and the drain-source current of the die located at the wafer edge within the same wafer.

[0051] In some embodiments, after depositing the thin film structure layer related to the product wafer 810 on the dummy wafer 700, the thin film on the dummy wafer 700 needs to be removed so that the dummy wafer 700 can be reused. The step of removing the thin film is carried out simultaneously with the cleaning step in the furnace tube. For example, during the preventive maintenance (PM) process of the furnace tube, the dummy wafer 700 is placed in the crystal boat 410 and cleaned by using clean gases or chemicals, such as nitrogen, hydrogen, oxygen, etc., through the furnace tube system to remove residual impurities, chemicals or deposits in order to maintain the performance and stability of the furnace tube.

[0052] As described above, these embodiments of the present application do not exhaustively describe all details, nor do they limit the utility model to specific embodiments. Clearly, many modifications and variations can be made based on the above description. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the present application, thereby enabling those skilled in the art to make good use of the present application and modifications based on it. The scope of protection of this application should be determined by the scope defined by the claims of the present application and their equivalents.

Claims

1. A dummy wafer for thin film vapor deposition, comprising: The first surface pattern is located on the surface of the dummy wafer and close to the wafer center of the dummy wafer; as well as The second surface pattern is located on the surface of the dummy wafer and between the first surface pattern and the wafer edge of the dummy wafer. The vertical cross-sectional shape of the first surface pattern is different from that of the second surface pattern to form an adsorption force gradient distributed radially along the pseudo-wafer.

2. The dummy wafer according to claim 1, wherein, Each of the first surface pattern and the second surface pattern is a groove having a predetermined vertical cross-sectional shape.

3. The dummy wafer according to claim 2, wherein, The predetermined vertical cross-sectional shape includes one of the following shapes: rectangle, trapezoid, triangle.

4. The dummy wafer according to claim 3, wherein the dummy wafer further comprises a third surface pattern, the third surface pattern being located on the surface of the dummy wafer and between the first surface pattern and the second surface pattern, and the third surface pattern having a different vertical cross-sectional shape from the first surface pattern and the second surface pattern.

5. The dummy wafer according to claim 4, wherein, The vertical cross-sectional shapes of the first surface pattern, the second surface pattern, and the third surface pattern are rectangle, triangle, and trapezoid, respectively.

6. A thin film vapor deposition apparatus, comprising: tube body; A crystal boat, located inside the tube, is used to hold multiple product wafers; A heating device is located in the tube body, the heating device comprising a first heating element extending axially along the tube body and a second heating element located at the end of the tube body; as well as The dummy wafer as described in any one of claims 1 to 5, wherein the dummy wafer is located within the boat and adjacent to the plurality of product wafers.

7. The thin film vapor deposition apparatus according to claim 6, wherein, The dummy wafer is located above and / or below the plurality of product wafers.

8. The thin film vapor deposition apparatus according to claim 7, wherein, The dummy wafer is also located between two adjacent product wafers.

9. The thin film vapor deposition apparatus according to claim 6, wherein, The larger the surface area of ​​the surface pattern on the dummy wafer surface used to adjust the adsorption force on the process gas, the stronger the adsorption force on the process gas.

10. The thin film vapor deposition apparatus according to claim 9, wherein, Along the radial direction of the dummy wafer, the closer to the wafer center of the dummy wafer, the stronger the adsorption force of the surface pattern on the process gas.

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