WAFER POSITIONING PROCESS

Abstract

Methods for positioning a wafer, used in a thin-film process, comprising: Step S1: obtaining a state distribution of a first surface of a first wafer after performing the thin-film process on the first wafer, wherein the first surface is the surface opposite a surface on which the thin film is formed in the thin-film process, wherein the state distribution of the first surface comprises a distribution of the double derivative of the backside Z-height, ZDD, of the first surface; and Step S2: Determining whether the first wafer is located at an ideal positioning center, according to the state distribution of the first surface; if the first wafer is not located at the ideal positioning center, a positioning position of a second wafer, which is to be subjected to the thin-film process, is adjusted according to the state distribution of the first surface in order to position the second wafer at the ideal positioning center during the thin-film process; the step to adjust the positioning position of the second wafer according to the state distribution of the first surface includes: attaining a minimum value of the ZDD distribution of the first surface in each radial direction; a obtaining a radar diagram of the ZDD distribution of the first surface based on a radial distance between a position with the minimum value of the ZDD distribution and the first wafer center for each radial direction, wherein the radar diagram represents a distance between the position with the minimum value of the ZDD distribution and the ideal positioning center for each radial direction; Determining whether the first wafer is located at the ideal positioning center, according to the radar diagram of the ZDD distribution; and wherein the positioning position of the second wafer is adjusted according to the radar diagram of the ZDD distribution if the first wafer is not located at the ideal positioning center.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The present invention relates to semiconductor technology, in particular to a wafer positioning method and a semiconductor manufacturing device. 2. Description of the state of the art

[0002] The thin-film process is widely used in semiconductor manufacturing processes and consists of forming a thin layer on a semiconductor substrate, and it includes an oxidation process, an epitaxial process, a deposition process and the like.

[0003] The silicon epiaxial wafer is the most important material for integrated circuits. It is widely used for microprocessor units (MPUs), logic chips, flash memory, dynamic random-access memory (DRAM), and similar devices. The silicon epiaxial wafer offers advantages over a polished wafer in terms of yield and improved electronic component properties.

[0004] In a typical silicon epitaxial wafer fabrication process, a silicon substrate wafer is placed on a substrate in an epitaxial furnace, and epitaxial growth is generally performed at 1100 °C to 1150 °C in an environment of trichlorosilane (TCS), hydrogen chloride (HCl), and a dopant. The thickness of the epitaxial layer varies depending on the wafer's position on the substrate. Ensuring the wafer is positioned in the center of the substrate can improve the results of the epitaxial process, including the uniformity of the epitaxial layer thickness, the uniformity of the epitaxial layer's resistivity, the flatness of the epitaxial wafer, and other properties.

[0005] Currently, the conventional method for positioning the wafer on the substrate involves conveying the silicon wafer by a mechanical arm of a conveying device into an epitaxial chamber and visually inspecting the distance between the silicon wafer and the edge of the substrate to determine whether the wafer is centered on the substrate. Documents EP 1 429 375 A1, US 2011 / 0 073 037 A1, and JP 2014-127 595 A represent the prior art. The conventional method has at least two disadvantages, which are outlined below. 1. It can only be performed while the light in the chamber is switched on. However, switching on the light in the chamber requires switching the chamber off and lowering the temperature. This delays the routine manufacturing process. 2. In the actual epitaxy process, the wafer is generally stored on the substrate at a high temperature, such as 700 °C. Since the gas flow and temperature field of the chamber differ at high temperature compared to room temperature, the wafer's storage position in the actual process differs from the positioning position predicted at room temperature. Consequently, the optimal wafer positioning during the manufacturing process cannot be achieved.

[0006] Therefore, the present application provides a wafer positioning method to solve the above problems. SUMMARY

[0007] The abstract introduces a number of concepts in simplified form, which are described in more detail in the detailed description. This abstract of the present invention is not intended to limit the main elements or essential technical features of the claimed technical solutions, nor to limit the scope of the claimed technical solution.

[0008] To solve the problems of conventional technology, the present application provides a method for positioning a wafer, as specified in the pending claims. The wafer positioning method is applied in a thin-film process and comprises: Step S1: obtaining a state distribution of a first surface of a first wafer after performing the thin-film process on the first wafer, wherein the first surface is the surface opposite a surface on which the thin film is formed in the thin-film process; and Step S2: Determining whether the first wafer is located at an ideal positioning center, according to the state distribution of the first surface; if the first wafer is not located at the ideal positioning center, a positioning position of a second wafer to be subjected to the thin-film process is adjusted according to the state distribution of the first surface in order to position the second wafer at the ideal positioning center during the thin-film process.

[0009] In one embodiment, the state distribution of the first surface includes a distribution of the backside Z height double derivative (BZDD) at the first surface.

[0010] In one embodiment, the BZDD distribution of the first wafer surface is obtained by the step comprising: a measurement of the height of the first surface at a position at a distance from the first wafer center in one radial direction and a measurement of the height of the first surface at different distances and different radial directions; and a calculation of the ZDD distribution of the first surface in different radial directions based on the elevation data.

[0011] In one embodiment, the step to adjust the positioning position of the second wafer according to the state distribution of the first surface comprises: attaining a minimum value of the ZDD distribution of the first surface in each radial direction; a obtaining a radar diagram of the ZDD distribution of the first surface based on a diameter distance between a position with the minimum value of the ZDD distribution and the first wafer center in each radial direction, wherein the radar diagram represents a distance between the position with the minimum value of the ZDD distribution and the ideal positioning center in each radial direction; Determining whether the first wafer is located at the ideal positioning center, according to the radar diagram of the ZDD distribution; and wherein the positioning position of the second wafer is adjusted according to the radar diagram of the ZDD distribution if the first wafer is not located at the ideal positioning center.

[0012] In one embodiment, the step to adjust the positioning position of the second wafer to be subjected to the thin-film process comprises the following: a finding of a center point of the first wafer according to the radar diagram of the ZDD distribution; a comparison of the obtained center point of the first wafer with the ideal positioning center point in order to obtain a presetting vector of the center point of the first wafer relative to the ideal positioning center point; and adjusting the positioning position of the second wafer during the thin-film process according to the vector.

[0013] The radial direction is a direction from the center to the circumference of the first wafer. In one embodiment, the radial direction comprises multiple radial directions formed by several points fixed on the wafer circumference at equal intervals.

[0014] In one embodiment, the position at a distance from the first wafer center in a radial direction comprises several positions that are fixed at equal distances from each other in each radial direction.

[0015] In one embodiment, the thin-film process comprises an epitaxy process and / or a deposition process.

[0016] According to the present application, the state distribution of the wafer surface is recorded after the thin-film process, with the wafer surface positioned opposite a surface on which the thin film is formed. The wafer position is then adjusted accordingly. It is possible to achieve this wafer position adjustment in the chamber below the process temperature, so that the wafers can be positioned at the ideal positioning center point during the thin-film process. The quality of the thin film and the entire wafer (i.e., the epitaxial wafer) can be improved, and the results of the thin-film process can be enhanced. BRIEF DESCRIPTION OF THE DRAWING Fig. Figure 1 is a flowchart illustrating a method for positioning a wafer according to an embodiment of the present application. Fig. Figure 2 is a schematic view showing the setup of a substrate in a semiconductor manufacturing device. Fig. 3A and Fig. 3B are radar diagrams of the ZDD distribution on a first wafer according to an embodiment of the present application. Fig. 4A and Fig. 4B are radar diagrams of the ZDD distribution on a second wafer according to an embodiment of the present application. Fig. Figure 5 is a schematic view depicting a conveyor device in a semiconductor manufacturing apparatus. DETAILED DESCRIPTION OF THE EXECUTION FORM

[0017] Exemplary embodiments are provided in such a way that this disclosure is comprehensive and fully conveys its scope to those skilled in the field. Numerous specific details are set forth, such as examples of certain components, devices, and methods, to provide a thorough understanding of embodiments of the present disclosure. It will be obvious to those skilled in the art that certain details need not be used, that exemplary embodiments can be implemented in many different forms, and that none of these can be interpreted as limiting the scope of the disclosure. In some exemplary embodiments, well-known methods, well-known device setups, and well-known techniques are not described in detail.

[0018] For a thorough understanding of the present invention, the exact steps are set out in detail below to explain the technical solution of the present invention. The preferred embodiments of the present invention are described in detail below; however, the present invention may also include other embodiments in addition to the one described in detail below.

[0019] The terms used here serve only to describe specific examples and are not intended to be restrictive. As used here, the singular forms "ein," "eine," "der," "die," and "das" could also be interpreted as including the plural forms, unless the context clearly indicates otherwise. The terms "umfasst," "umfassend," "haltend," and "aufweisend" are inclusive and therefore indicate the presence of designated features, integers, steps, processes, elements, and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, processes, elements, components, and / or groups thereof. The procedural steps, sequences, and processes described here are not to be interpreted in such a way that their execution in the specific order described or depicted is absolutely necessary, unless specifically indicated as an execution sequence.It goes without saying that additional or alternative steps may be used.

[0020] It is understood that the present invention can be implemented in practice in various forms, and that it should not be interpreted in such a way as to limit the scope of the disclosed examples. On the contrary, the examples are provided to achieve a full and complete disclosure and to allow those skilled in the art to fully grasp the scope of the present invention. In the drawing, the size and relative size of layers and surfaces may be exaggerated for clarity. In the drawing, the same reference number denotes the same element. EXAMPLES Example 1

[0021] To solve the problems of conventional technology, the present application provides a method for positioning a wafer, characterized as being used in a thin-film process, comprising: Step S1: obtaining a state distribution of a first surface of a first wafer after performing the thin-film process on the first wafer, wherein the first surface is the surface opposite a surface on which the thin film is formed in the thin-film process; and Step S2: Determining whether the first wafer is located at an ideal positioning center, according to the state distribution of the first surface; if the first wafer is not located at the ideal positioning center, a positioning position of a second wafer to be subjected to the thin-film process is adjusted according to the state distribution of the first surface in order to position the second wafer at the ideal positioning center during the thin-film process.

[0022] Since the conventional wafer positioning method requires lowering the chamber temperature to room temperature, the routine manufacturing process is significantly delayed. Furthermore, the actual process temperature in the chamber is generally high, e.g., 700 °C, which alters the positioning position predicted at room temperature. As a result, the ideal wafer position cannot be achieved during the manufacturing process. The wafer positioning method of the present application is capable of achieving the wafer position below the process temperature and avoids lowering the chamber temperature. Wafer positioning can be performed with high efficiency, time savings, and high accuracy. Consequently, the quality of the thin film on the wafer can be improved, and the results of the thin-film process can be enhanced.

[0023] The method for positioning a wafer of the present application is described with reference to Fig. 1, Fig. 2, Fig. 3A and Fig. 3B as well as 4A and 4B are described in an illustrative manner. Fig. Figure 1 is a flowchart illustrating a method for positioning a wafer according to an embodiment of the present application. Fig. Figure 2 is a schematic view showing the setup of a substrate in a semiconductor manufacturing device. Fig. 3A and Fig. 3B are radar diagrams of the ZDD distribution on a first wafer according to an embodiment of the present application. Fig. 4A and Fig. 4B are radar diagrams of the ZDD distribution on a second wafer according to an embodiment of the present application.

[0024] With reference to Fig. 1. Step S1 is performed: obtaining a state distribution of a first surface of a first wafer after performing the thin-film process on the first wafer, where the first surface is the surface opposite a surface on which the thin film is formed in the thin-film process.

[0025] In semiconductor manufacturing processes, the thin-film process generally includes an oxidation step, a deposition step, and an epitaxial step. In the present application, the thin-film process includes the deposition step and / or the epitaxial step. During the deposition and epitaxial steps, the wafer is placed under an atmosphere of chemicals with specific environmental conditions; the chemical is deposited onto the wafer surface and grows into a thin film. The deposition and growth of the thin film are highly sensitive to the condition of the wafer surface. Because the wafer's state distribution is influenced by variations in its positioning position, this affects the condition and quality of the thin film formed on the wafer and of the wafer as a whole. The wafer must be positioned precisely at an ideal positioning center point during the thin-film process.

[0026] In the thin-film process, due to the influence of the wafer support device (i.e., the substrate) in the processing chamber, different state distributions are formed on the wafer surface compared to the layer formation area. In one embodiment, the wafer edge generally exhibits different distributions because the wafer is supported on and influenced by the wafer support device. Based on this characteristic, the present application consists of adjusting the wafer positioning position based on the acquisition results of the state distribution of the first surface of the wafer, where the first surface is the surface opposite the thin-film formation area.It is possible to adjust the wafer positioning position under the process temperature, to ensure that the wafer is positioned at the ideal positioning center point during the thin-film process, and to improve the results of the thin-film process, including uniformity of layer thickness, uniformity of resistivity, and flatness of the entire wafer (epitaxic wafer), such as SFRQ.

[0027] With reference to Fig. Figure 2 shows a schematic view of a typical wafer support device used in the thin-film process. In a typical epitaxial process, a processing chamber of an epitaxial device contains a support 200 for a wafer 100, and the support 200 comprises a first part 201 and a second part 202. The second part 202 has an inner diameter D that is slightly smaller than the wafer diameter. This is used to support the wafer during the thin-film process and to cool it. In the thin-film process, the second part 202 is in contact with the edge of the first surface of the wafer, i.e., the surface opposite the thin-film formation area of ​​the wafer. This causes various influences on the heating conditions of the first surface of the wafer 100, and thus affects the condition of the first surface of the wafer 100.

[0028] The present application uses the state distribution of the first surface of the first wafer to determine whether the positioning of the first wafer is accurate and provides a target for subsequent wafer positioning to effectively increase positioning accuracy. Simultaneously, the adjustment is based on a calculation, without visual inspection, and can be performed under the process conditions of the thin-film process. This avoids the problems of having to perform positioning while the processing chamber is shut down and of not achieving optimal positioning due to changes in positioning between room temperature and process temperature.Furthermore, in the present application, since the positioning method is based on the state of the first surface but not on the surface state of the thin film, the effects of the thin-film method itself on the layer uniformity can be eliminated, and the accuracy of the wafer positioning can be increased.

[0029] In embodiments, the first wafer comprises at least one wafer. The first wafer comprises any one or more wafers that have undergone the thin-film process. For example, in the continuous thin-film process, positioning for the first tray of wafers is performed, the thin-film process is carried out for the first tray of wafers, and the state distribution of the first surface of any one or more wafers in the first tray is obtained after the thin-film process for the first tray. Or, the state distribution of the first surface of the first wafers that have undergone the thin-film process is obtained before the thin-film process of the second wafer.

[0030] In one embodiment, the state distribution of the first wafer comprises a distribution of the backside Z-height double derivative (BZDD) of the surface of the first wafer. The BZDD distribution is obtained by sensing the height of the wafer surface, calculating a second derivative of the height, and acquiring height distribution data of the wafer's backside. According to the thin-film method, such as an epitaxial method, the value of the BZDD distribution of the substrate wafer surface is smallest at the position where the wafer makes contact with the second part 202. It can be influenced, for example, by cooling the second part 202 of the substrate 200. The position where the wafer makes contact with the second part 202 is determined in Fig. 2 is indicated by circle A. Based on the distribution of the smallest values ​​of the BZDD distribution on the wafer surface along the direction of the wafer circumference, it can be determined during the thin-film method whether the wafer is positioned in the middle of the second part 202, i.e., in the ideal positioning center.

[0031] It should be emphasized that in this example, the applied BZDD distribution with respect to the height of the first surface is only illustrative. An ordinary person skilled in the art understands that any devices representing the distribution state of the first surface of the wafer, such as thickness uniformity, resistivity uniformity, and flatness (e.g., as SFQR), can be applied in the present application to achieve equivalent effects.

[0032] In one embodiment, the method for obtaining the BZDD distribution of the first wafer surface includes: Step S21: acquiring a height of the first surface at a position at a distance from the first wafer center in one radial direction and obtaining height data of the first surface at different distances and different radial directions;

[0033] Step S22: calculating the ZDD distribution of the first surface in different radial directions based on the elevation data.

[0034] The radial direction is a direction from the center to the circumference of the first wafer. In one embodiment, the radial direction comprises multiple radial directions. The radial directions are defined by several points fixed on the wafer's circumference at equal intervals, meaning that any two adjacent radial directions form the same angle. In one embodiment, the angle formed by any two adjacent radial directions is 5°, resulting in a total of 72 defined radial directions.

[0035] In one embodiment, the position that is located at a distance along a radial direction from the first wafer center comprises multiple positions. The positions are defined along a radial direction with an equal distance between two adjacent positions. Each radial direction can have multiple positions. In one embodiment, the distance between the positions to be detected along each radial direction is 0.2 mm.

[0036] The above numbers for radial direction and position are given as examples and without restriction, and any numbers for radial direction and position can be applied as long as the distribution state of the first wafer surface can be reproduced.

[0037] After obtaining the height data for different radial directions and different distances on the first surface, the ZDD distribution (also known as BZDD distribution) of the height of the first surface of the first wafer for different radial directions is calculated. One embodiment includes the following steps:

[0038] Step S221: The average height, Zmean(R), of the positions is calculated that have the same distance from the first wafer center to the position for each radial direction θ.

[0039] Step S222: Based on the average height Zmean and the distance R from the first wafer center to the position, S = dZmean(R) / dR is used to obtain a radial slope S. Matlab software can be used for fitting in this step.

[0040] Step S223: ZDD is calculated, whereby ZDD(R)=∂2Zmean(R)∂R2

[0041] From the calculations above, the ZDD value can be obtained at various positions on the first surface of the first wafer, and furthermore, the ZDD (BZDD) distribution of the height of the first surface of the first wafer can be determined. Based on the BZDD distribution, it can be determined whether the center of the first wafer is the center of the circle enclosed by the first surface heights mentioned above; this allows us to determine whether the first wafer is located in the center of the substrate, i.e., at the ideal positioning center, during the thin-film process.

[0042] Still with reference to Fig. Step 2 is performed. It determines whether the first wafer is located at an ideal positioning center, according to the state distribution of the first surface; if the first wafer is not located at the ideal positioning center, a positioning position of a second wafer, which is to be subjected to the thin-film process, is adjusted according to the state distribution of the first surface in order to position the second wafer at the ideal positioning center during the thin-film process.

[0043] To determine whether the first wafer is located at an ideal positioning center, the determination steps based on the ZDD distribution are shown below.

[0044] In this example, the BZDD distribution is used in the determination steps. However, any state distribution of the first surface of the first wafer can be applied in the present application and achieve equivalent effects.

[0045] First, a minimum value of the BZDD distribution of the first wafer is obtained in each radial direction.

[0046] In one embodiment, the BZDD distribution is influenced by the second part 202 of the substrate 200, such as by the cooling factor; that is, the distribution state of the first surface at the edge of the first wafer is affected. Accordingly, only the height of the first surface at the edge of the first wafer is sampled and analyzed to obtain the BZDD distribution data. For example, the first wafer 100 has a diameter of 300 mm, and the second part 202 of the substrate 200 of the thin-film manufacturing device has an inner diameter D of 290 mm. Therefore, the height data of the first wafer 100 at a radius of 140 to 148 mm are used to obtain the BZDD distribution and the minimum value of the BZDD distribution.

[0047] Based on the positions in each radial direction that exhibit the minimum value of the BZDD distribution, the radar diagram of the ZDD distribution of the first wafer surface is generated. The radar diagram of the ZDD distribution shows, in each radial direction, the distance between the positioning center of the first wafer and the position with the minimum value of the BZDD distribution. It is understood that the center of the first wafer used for height sensing is the same as the ideal positioning center of the thin-film method, i.e., the center of the first wafer itself. With reference to Fig. 3A and Fig. Figure 3B shows the radar diagrams of the ZDD distribution on a first wafer according to an embodiment of the present application. Fig. 3A is the top view showing the load of the first wafer on the substrate. Fig. 3B is the radar diagram of the ZDD distribution of the first wafer according to Fig. 3A. As in Fig. As shown in Figure 3B, for each radial direction, each point is the position with the minimum value of the BZDD distribution and shows the distance between the position and the ideal positioning center O, i.e., the center of the first wafer itself.

[0048] Based on the radar diagrams of the ZDD distribution, it is determined whether the first wafer is located at an ideal positioning center. If the first wafer is not located at the ideal positioning center, the positioning position of the second wafer, which is to undergo the thin-film process, is adjusted according to the radar diagrams of the ZDD distribution. The radar diagram of the ZDD distribution shows the distribution of the minimum value of the BZDD distribution in different radial directions on the wafer.

[0049] As in Fig. As shown in Figure 3A, the first wafer 100 is not located at the ideal positioning center of the substrate 200, and the radar diagram of the ZDD distribution represents an irregular circle that deviates significantly from the ideal positioning center O of the substrate 200. The first wafer is clearly not located at the ideal positioning center, so an adjustment to position the second wafer based on the radar diagram of the ZDD distribution is required.

[0050] Similarly, the second wafer comprises at least one wafer. The second wafer comprises one or more wafers to be subjected to the thin-film process. For example, in the continuous thin-film process, positioning is performed to position a box of wafers or a single wafer. Therefore, after the state distribution of the first surface of the first wafer is obtained from step S1, the subsequent positioning step can be performed for a box of wafers or a single wafer, without limitation.

[0051] An example adjustment of the positioning of the second wafer according to the radar diagrams of the ZDD distribution is explained below.

[0052] First, the positioning center of the first wafer in the thin-film process is obtained from the radar diagrams of the ZDD distribution. With reference to Fig. 3A is the positioning center of the first wafer in the thin-film process, obtained from the radar diagrams of the ZDD distribution, P. The procedure for obtaining the positioning center includes an image simulation. The image simulation software is used to simulate the radar diagrams of the ZDD distribution as a circle and to position the circle to obtain the center point as the positioning center of the first wafer in the thin-film process.

[0053] It then compares the positioning center of the first wafer in the thin-film process with the ideal positioning center to obtain a presetting vector of the first wafer center relative to the ideal positioning center. In this example, as in Fig. Figure 3A shows O as the ideal positioning center, and P as the positioning center of the first wafer in the thin-film process. The actual center P deviates significantly from the ideal positioning center O, and the presetting vector is subsequently obtained. As shown in Fig. As shown in Figure 3B, the presetting vector O→P has a length ρ and a direction of a backward angle α to the X-axis.

[0054] The vector O→P is used to adjust the positioning position of the second wafer in the thin-film process. In one embodiment of the present application, the radar diagram of the ZDD distribution of the second wafer after adjustment of the positioning position is shown in Fig. 4A and Fig. 4B shown.

[0055] Fig. 4A is the top view showing the load of the second wafer 300 on the base 200. Fig. 4B is the radar diagram of the ZDD distribution of the second wafer. As in Fig. As shown in Figure 4B, the radar diagrams C of the ZDD distribution of the second wafer have a circle center P that coincides with the ideal positioning center, i.e., the adjusted center of the second wafer is located at the ideal positioning center.

[0056] In one embodiment, the flatness of the thin layer on the wafer is measured after completion of the wafer positioning and thin-film processes. A sample measuring 26 mm x 8 mm is taken from 2 mm from the wafer edge and tested. The flatness SFQR value of the wafer surface can be improved by 20% to 80% by applying the positioning method of the present application.

[0057] According to the present application, by capturing the state distribution of the first surface of the first wafer after the thin-film process, the wafer positioning can be adjusted under the process temperature. In the thin-film process, the wafer can be located at the ideal positioning center; this allows for improvements in the thickness uniformity of the thin film, the uniformity of the resistivity, and the flatness of the entire epitaxial wafer, such as the SFQR value. Example 2

[0058] With reference to Fig. 2, Fig. 5 as well Fig. 3A and Fig. Figure 3B shows an exemplary semiconductor manufacturing device. Fig. Figure 2 is a schematic view showing the setup of a substrate in a semiconductor manufacturing device. Fig. 3A and Fig. 3B are radar diagrams of the ZDD distribution on a first wafer according to an embodiment of the present application. Fig. Figure 5 is a schematic view depicting a conveyor device in a semiconductor manufacturing apparatus.

[0059] In one embodiment, the wafer storage device includes a base. With reference to Fig. 2 The substrate 200 contains a first part 201 and a second part 202. The first part 201 confines the wafer to the second part 202. The second part 202 serves to support the wafer and to cool the wafer during the thin-film process.

[0060] In one embodiment, the semiconductor manufacturing device further includes a conveying device for transferring the wafer to the wafer storage device. The step for adjusting the positioning position of the second wafer according to the thickness distribution includes adjusting the conveying device according to the thickness distribution.

[0061] In one embodiment, the conveying device includes a mechanical arm. With reference to Fig. The conveying device includes a mechanical arm 400. The wafer 100 is conveyed via the mechanical arm 400 onto the support 200. The support 200 contains a three-pin device 500. When the mechanical arm 400 carries the wafer 100 and extends above the support 200, the three-pin device 500 rises through the mechanical arm 400 and carries the wafer 100. When the mechanical arm 400 retracts, the three-pin device 500 lowers to place the wafer onto the support 200. The extension position of the mechanical arm 400 can be adjusted, thereby adjusting the storage position of the wafer 100 on the support 200. Wafer positioning is achieved according to the above procedure.

[0062] In one embodiment, the step of adjusting the positioning position of the second wafer to be subjected to the thin-film process, according to the state distribution of the first surface, includes adjusting the mechanical arm according to the state distribution of the first surface.

[0063] In one embodiment, the BZDD distribution is used to represent the surface distribution of the first wafer surface. The radar diagram of the ZDD distribution is generated based on the minimum value of the ZDD distribution for each radial direction. The positioning position of the second wafer is adjusted according to the radar diagrams of the ZDD distribution. As in Fig. 3A and Fig. As shown in Figure 3B, the presetting vector O→P is obtained with a length ρ and a direction of a backward angle α with the X-axis. This adjusts the position of the mechanical arm according to the presetting vector O→P.

[0064] In one embodiment, the horizontal and / or vertical offset can be adjusted according to the preset vector O→P; this allows the positioning position of the second wafer to be adjusted. For example, based on the preset vector O→P, a deviation of 0.07 mm to the left and a deviation of 0.06 mm upwards are obtained for the first wafer. The mechanical arm can be adjusted to shift 0.07 mm to the right and 0.06 mm downwards. Accordingly, the second wafer can be positioned at the ideal center point of the support.

[0065] In one embodiment, the flatness of the thin layer on the wafer is measured after completion of the wafer positioning and thin-film processes. A sample measuring 26 mm x 8 mm is taken from 2 mm from the wafer edge and tested. The flatness SFQR value of the wafer surface can be improved by 20% to 80% by applying the positioning method of the present application.

[0066] While the present invention is disclosed by reference to the preferred embodiment and examples described in detail above, it is understood that these examples are intended to be illustrative and not limiting. It is considered that those skilled in the art will readily conceive of variations and combinations; these variations and combinations fall within the spirit of the invention and the scope of the following claims and their equivalent systems and methods.

Claims

[1] Method for positioning a wafer used in a thin-film process, comprising: Step S1: obtaining a state distribution of a first surface of a first wafer after performing the thin-film process on the first wafer, wherein the first surface is the surface opposite a surface on which the thin film is formed in the thin-film process, wherein the state distribution of the first surface comprises a distribution of the double derivative of the backside Z-height, ZDD, of the first surface; and Step S2: Determining whether the first wafer is located at an ideal positioning center, according to the state distribution of the first surface; if the first wafer is not located at the ideal positioning center, a positioning position of a second wafer, which is to be subjected to the thin-film process, is adjusted according to the state distribution of the first surface in order to position the second wafer at the ideal positioning center during the thin-film process; the step to adjust the positioning position of the second wafer according to the state distribution of the first surface includes: attaining a minimum value of the ZDD distribution of the first surface in each radial direction; a obtaining a radar diagram of the ZDD distribution of the first surface based on a radial distance between a position with the minimum value of the ZDD distribution and the first wafer center for each radial direction, wherein the radar diagram represents a distance between the position with the minimum value of the ZDD distribution and the ideal positioning center for each radial direction; Determining whether the first wafer is located at the ideal positioning center, according to the radar diagram of the ZDD distribution; and wherein the positioning position of the second wafer is adjusted according to the radar diagram of the ZDD distribution if the first wafer is not located at the ideal positioning center. [2] The method of claim 1, wherein the backside ZDD distribution of the first wafer surface is obtained by the step comprising: a measurement of the height of the first surface at a position at a distance from the first wafer center in one radial direction and a measurement of the height of the first surface at different distances and different radial directions; and a calculation of the ZDD distribution of the first surface for different radial directions based on the elevation data. [3] Method according to claim 1, wherein the step to adjust the positioning position of the second wafer comprises: a finding of a center point of the first wafer according to the radar diagram of the ZDD distribution; a comparison of the obtained center point of the first wafer with the ideal positioning center point in order to obtain a presetting vector of the center point of the first wafer relative to the ideal positioning center point; and adjusting the positioning position of the second wafer during the thin-film process according to the vector. [4] Method according to claim 1, wherein the radial direction is a direction from the center to the circumference of the first wafer, and the radial direction comprises multiple radial directions formed by multiple points fixed on the wafer circumference with equal spacing between these points. [5] Method according to claim 2, wherein the position at a distance from the first wafer center in a radial direction comprises several positions which are fixed at equal distances from each other in each radial direction. [6] Method according to claim 1, wherein the thin-film method comprises an epitaxy method and / or a deposition method.

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