Film thickness monitoring wafer and manufacturing method thereof

Abstract

The invention discloses a film thickness monitoring wafer and a manufacturing method thereof. The manufacturing method comprises the following steps: providing a wafer substrate; forming a thin film for monitoring on one side of the substrate; a film thickness monitoring structure located in the film is formed on the side, away from the substrate, of the film, the film thickness monitoring structure is provided with a plurality of step faces which are arranged from the edge of the substrate to the center direction, the height gradient of the step faces is reduced, and the step faces serve as measuring faces. The film thickness monitoring structure with a plurality of measuring surfaces can be formed in one or more films on one film thickness monitoring wafer, the completeness of a film thickness monitoring project can be ensured, the monitoring efficiency can be improved, the number of standby libraries of the film thickness monitoring wafer can be greatly reduced, and the cost is saved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor testing technology, and in particular to a film thickness monitoring wafer and a manufacturing method thereof. Background Art

[0002] The film thickness measuring machine is mainly used to measure the thickness of the film deposited on the wafer, so as to measure whether the product manufacturing process meets the standard requirements through the deposition thickness of the film. The accuracy and stability of the film thickness measurement are crucial to the electrical performance and stability of the product, so the accuracy and stability of the film thickness measuring machine itself during measurement is particularly important.

[0003] In order to more accurately monitor the accuracy and stability of the film thickness measuring machine, a variety of film thickness monitoring items are usually set for the film thickness measuring machine, and the film thickness monitoring wafer is used for measurement to monitor the accuracy and stability of the film thickness measuring machine. Among them, the film thickness monitoring items include requirements for measuring films of various materials, each of which includes various different thicknesses. Therefore, the more complex the types of films for online products, the greater the demand for film thickness monitoring wafers.

[0004] At present, the industry prepares the required number of film thickness monitoring wafers according to the product of the number of film types and the number of different thickness specifications of each film. If the film thickness monitoring wafers are prepared according to the above method, only one layer of film of the same material and single thickness can be formed on each film thickness monitoring wafer, and it can be used to measure one film thickness monitoring project. In addition, each time monitoring is performed, multiple film thickness monitoring wafers need to be loaded into the film thickness measuring machine in sequence, and unloaded from the film thickness measuring machine in sequence after measurement. In this way, the time consumed in loading and unloading (including the edge search time before each measurement) is longer than the measurement time of the film thickness measuring machine, which seriously wastes the production capacity of the film thickness measuring machine. In addition, preparing a sufficient number of film thickness monitoring wafers also requires a lot of costs.

[0005] Therefore, it is necessary to provide a novel film thickness monitoring wafer and a manufacturing method thereof to solve the above-mentioned problems existing in the prior art. Summary of the invention

[0006] The purpose of the present invention is to overcome the above-mentioned defects in the prior art and provide a film thickness monitoring wafer and a method for manufacturing the same.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] According to a first aspect of the present invention, the present invention provides a method for manufacturing a film thickness monitoring wafer, comprising:

[0009] providing a wafer substrate;

[0010] forming a monitoring thin film on one side of the substrate;

[0011] A film thickness monitoring structure is formed in the film on a side of the film away from the substrate. The film thickness monitoring structure has a plurality of step surfaces with decreasing height gradient arranged from the edge of the substrate toward the center. The step surfaces serve as measurement surfaces.

[0012] Furthermore, by patterning the thin film, the film thickness monitoring structure located in the thin film is formed on the surface of the film away from the substrate, and a concentric circle structure with the center of the substrate as the center is formed between the boundaries of each step surface of the film thickness monitoring structure.

[0013] Furthermore, the patterning of the film specifically includes:

[0014] defining a photoresist spraying point on the surface of the film;

[0015] Spinning photoresist on the surface of the film with the photoresist spraying point as the starting point, so as to form an annular photoresist layer with the center of the substrate as the center between the photoresist spraying point and the edge of the substrate;

[0016] Using the annular photoresist layer as a mask, the surface of the thin film exposed on the inner side is etched to form a sunken circular step surface on the thin film surface inside the annular photoresist layer, and a corresponding annular step surface with a height higher than the circular step surface is formed on the thin film surface outside the circular step surface, thereby obtaining the film thickness monitoring structure having the two measuring surfaces formed by the annular step surface and the circular step surface.

[0017] Furthermore, it also includes:

[0018] The same method is repeatedly used to define new photoresist spraying points on the surface of the film, so that the distance between each newly defined photoresist spraying point and the edge of the substrate is greater than the distance between the photoresist spraying point defined last time and the edge of the substrate, and each time the photoresist is spin-coated at the newly defined photoresist spraying point and etched accordingly, a new circular step surface and a new annular step surface are formed on the circular step surface formed last time, so that multiple annular step surfaces with heights successively higher than the central circular step surface are formed outside the circular step surface located in the center formed last time, so as to obtain the film thickness monitoring structure with at least three measuring surfaces formed by the central circular step surface and each annular step surface.

[0019] Furthermore, the film is a single-layer film.

[0020] Furthermore, the film is a double-layer film made of different materials, the annular step surface is located on the upper film in the double-layer film, and the circular step surface is located on the lower film in the double-layer film.

[0021] Furthermore, the film is a multilayer film made of different materials, the central circular step surface is located on the bottommost film layer of the multilayer film, and the annular step surface is located on at least each film layer above the bottommost film layer of the multilayer film.

[0022] Furthermore, at least one annular step surface is formed on each layer of film above the bottommost layer of the multi-layer film.

[0023] Furthermore, at least one annular step surface located outside the central circular step surface is formed on the bottommost layer of the multi-layer film.

[0024] Furthermore, the thickness of each layer of the multilayer film is the same or different.

[0025] Furthermore, the etching depth during each etching process is the same or different.

[0026] Furthermore, the process of etching the surface of the thin film exposed on the inner side by using the annular photoresist layer as a mask specifically includes:

[0027] Performing photolithography without a mask on the spin-coated photoresist to form a ring-shaped photoresist layer;

[0028] The annular photoresist layer is used as a mask to perform anisotropic etching on the surface of the film exposed on the inner side.

[0029] Furthermore, the widths of the step surfaces along the radial direction of the substrate are the same or different.

[0030] Furthermore, the material of the film includes a light-transmitting medium.

[0031] Furthermore, the light-transmitting medium includes at least one of silicon oxide, silicon nitride, and silicon oxynitride.

[0032] According to a second aspect of the present invention, the present invention provides a film thickness monitoring wafer, which is manufactured using the above-mentioned method for manufacturing a film thickness monitoring wafer.

[0033] It can be seen from the above technical scheme that the present invention forms a monitoring film on one side of the wafer substrate, and forms a film thickness monitoring structure located in the film on the side of the film away from the substrate, so that the film thickness monitoring structure has multiple step surfaces arranged from the edge of the substrate to the center and with a decreasing height gradient and serving as measurement surfaces. A film thickness monitoring structure with multiple measurement surfaces can be formed in a film of one material on a film thickness monitoring wafer, or a film thickness monitoring structure with at least one measurement surface can be formed in multilayer films of different materials, thereby ensuring the integrity of the film thickness monitoring project and reducing the machine time occupied during monitoring, thereby improving monitoring efficiency, increasing machine capacity, and greatly reducing the number of film thickness monitoring wafers in stock, saving costs. The present invention has the following advantages:

[0034] (1) It is possible to realize the presence of film layer measurement surfaces of different thicknesses in a thin film of the same material on a same film thickness monitoring wafer, or to respectively present film layer measurement surfaces of different thicknesses in multiple layers of thin films of different materials on the same film thickness monitoring wafer, and to form a combination of the first two and use them alternately, thereby realizing the effect of using one film thickness monitoring wafer to monitor multiple thin films and multiple thicknesses, thereby increasing monitoring efficiency and saving production capacity consumed by waiting time.

[0035] (2) Multiple film thickness monitoring projects can be completed with only one loading and unloading, which can greatly reduce the loading and unloading time and effectively improve the machine capacity.

[0036] (3) It can significantly reduce the demand for film thickness monitoring wafers, effectively reducing costs.

[0037] (4) The film thickness monitoring wafer can be produced without using a mask, effectively reducing the mask expenses. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The present invention is a flowchart of a method for manufacturing a film thickness monitoring wafer according to a preferred embodiment of the present invention.

[0039] Figure 2 The figure is a schematic diagram of a manufacturing process of a film thickness monitoring wafer made of thin films of the same material according to a preferred embodiment of the present invention.

[0040] Figure 3 The figure is a schematic diagram of a manufacturing process of a film thickness monitoring wafer made of thin films of various materials according to a preferred embodiment of the present invention.

[0041] Figure 4-Figure 5 A preferred embodiment of the present invention is based on Figure 2 Schematic diagram of the structure of the film thickness monitoring wafer produced by the production process.

[0042] Figure 6-Figure 7A preferred embodiment of the present invention is based on Figure 3 Schematic diagram of the structure of the film thickness monitoring wafer produced by the production process.

[0043] Figure 8 A preferred embodiment of the present invention is based on Figure 2 and Figure 3 Schematic diagram of the structure of a film thickness monitoring wafer produced by a combination of production processes. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be understood by people with general skills in the field to which the present invention belongs. "Including" and similar words used in this article mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects.

[0045] At present, the industry prepares the required number of film thickness monitoring wafers according to the product of the number of film types and the number of different thickness specifications of each film. Only one layer of film with the same material and single thickness can be formed on each film thickness monitoring wafer, and it is used for measuring one film thickness monitoring project. Each time monitoring is performed, multiple film thickness monitoring wafers need to be loaded into a film thickness measuring machine in sequence, and unloaded from the film thickness measuring machine in sequence after measurement, resulting in the time consumed in loading and unloading (including the edge search time before each measurement) being longer than the measurement time of the film thickness measuring machine, thereby seriously wasting the production capacity of the film thickness measuring machine and consuming a large amount of cost due to preparing a sufficient number of film thickness monitoring wafers. The present invention provides a method for manufacturing a film thickness monitoring wafer.

[0046] refer to Figure 1 A method for manufacturing a film thickness monitoring wafer according to the present invention comprises:

[0047] providing a wafer substrate;

[0048] forming a monitoring thin film on one side of the substrate;

[0049] A film thickness monitoring structure is formed in the film on a side of the film away from the substrate. The film thickness monitoring structure has a plurality of step surfaces with decreasing height gradient arranged from the edge of the substrate toward the center. The step surfaces serve as measurement surfaces.

[0050] The present invention also provides a film thickness monitoring wafer manufactured according to the method for manufacturing the film thickness monitoring wafer of the present invention.

[0051] The present invention can form annular film layer measurement surfaces of different thicknesses in a thin film of the same material on a same film thickness monitoring wafer, or can respectively form annular film layer measurement surfaces of different thicknesses in multiple layers of thin films of different materials on the same film thickness monitoring wafer, and can form a combination of the former two and use them alternately, thereby achieving the effect of using one film thickness monitoring wafer to monitor multiple films and multiple thicknesses, increasing monitoring efficiency and saving production capacity consumed by waiting time.

[0052] The specific implementation modes of the present invention are further described in detail below in conjunction with the accompanying drawings.

[0053] refer to Figure 2 The present invention provides a method for manufacturing a film thickness monitoring wafer, which uses a monitoring film of the same material to manufacture a film thickness monitoring wafer, and the manufacturing process includes the following steps:

[0054] like Figure 2 As shown in (a), a wafer substrate 10 is used to manufacture a film thickness monitoring wafer formed of a thin film of the same material according to the present invention.

[0055] In some embodiments, the wafer substrate 10 may be, for example, a silicon wafer substrate 10. However, the present invention is not limited thereto, and any wafer substrate 10 suitable for use as a film thickness monitoring wafer may be used, such as a germanium wafer substrate 10, a silicon carbide wafer substrate 10, and the like.

[0056] like Figure 2 As shown in (a), a monitoring thin film 11 is formed on one side of a substrate 10.

[0057] In some embodiments, the monitoring thin film 11 is formed on the upper surface of the substrate 10 and is made of the same material. That is, the monitoring thin film 11 is a single-layer thin film 11 formed on the upper surface of the substrate 10 and is made of the same material.

[0058] In some embodiments, the same process as that for preparing the corresponding thin film in production is used to form a monitoring thin film 11 of the same material on the upper surface of the substrate 10 as shown in the figure. For example, the thin film preparation process in production may include one of CVD, PVD, ALD, etc. The same process as that for preparing the corresponding thin film in production is used to form a monitoring thin film 11 of the same material on the upper surface of the substrate 10.

[0059] In some embodiments, the material of the film 11 includes a light-transmitting medium.

[0060] Furthermore, the light-transmitting medium includes any one of silicon oxide, silicon nitride, and silicon oxynitride. However, it is understandable that the light-transmitting medium may also be any other light-transmitting medium that can be used for monitoring except silicon oxide, silicon nitride, and silicon oxynitride.

[0061] Then, a film thickness monitoring structure is formed in the film 11 on the side of the film 11 away from the substrate 10, so that the film thickness monitoring structure has a plurality of step surfaces with a decreasing height gradient arranged from the edge of the substrate 10 toward the center, and the step surfaces are used as the measuring surfaces of the film thickness monitoring structure for monitoring the film thickness measuring machine.

[0062] In some embodiments, by patterning the thin film 11 formed in the above steps, a film thickness monitoring structure located in the thin film 11 is formed on the upper surface of the thin film 11, and a concentric circle structure with the center of the substrate 10 as the center is formed between the boundaries of each step surface formed in the film thickness monitoring structure. For example, Figure 4 and Figure 5 The following is shown in Figure 2 According to the manufacturing process, three step surfaces with decreasing height gradient arranged from the edge of the substrate 10 to the center are formed on the upper surface of the film 11 (that is, the film thickness at the three step surfaces decreases in sequence), which are the first annular step surface 111, the second annular step surface 112 and the central circular step surface 113. Among them, the first annular step surface 111 and the second annular step surface 112 respectively form concentric circular rings with the center of the substrate 10 as the center, and the central circular step surface 113 forms a circle with the center of the substrate 10 as the center. As a result, the boundary between the first annular step surface 111 and the second annular step surface 112, and the boundary between the second annular step surface 112 and the central circular step surface 113 are both circular, and a concentric circle structure with the center of the substrate 10 as the center is formed.

[0063] In some embodiments, according to Figure 2 The film 11 is patterned by the production process, which specifically includes the following methods:

[0064] like Figure 2 As shown in (b), a photoresist spraying start point is defined on the upper surface of the formed film 11. The photoresist spraying start point is the initial landing point on the surface of the film 11 when the photoresist nozzle starts to spray the photoresist. In this embodiment, a first photoresist spraying start point 211 is first defined on the upper surface of the film 11, so that the first photoresist spraying start point 211 is at a first distance from the edge of the substrate 10, or the first photoresist spraying start point 211 is at a distance from the center of the substrate 10 by a first spin coating radius R1.

[0065] Then, the first photoresist spraying start point 211 is used as the starting point (initial landing point) when the photoresist starts to be sprayed on the surface of the film 11, and the first photoresist is spin-coated on the surface of the film 11. Under the action of the centrifugal force when the substrate 10 rotates, the first photoresist will be spin-coated according to the first spin-coating radius R1, so it only covers the annular area from the outside of the first photoresist spraying start point 211 to the edge of the substrate 10, such as Figure 2 Thus, a first annular photoresist layer 21 with the center of the substrate 10 as the center can be formed between the first photoresist spraying point 211 and the edge of the substrate 10.

[0066] like Figure 2 As shown in (c), then, the first annular photoresist layer 21 is used as a mask to etch the surface of the film 11 exposed inside the first annular photoresist layer 21. After etching, a sunken first circular step surface 110 is formed on the surface of the film 11 inside the first annular photoresist layer 21, and at the same time, a first annular step surface 111 with a height higher than the first circular step surface 110 is formed on the surface of the film 11 outside the first circular step surface 110 (i.e., the coverage area corresponding to the first annular photoresist layer 21) (refer to Figure 2 (d)). Thus, after removing the first annular photoresist layer 21, two measuring surfaces formed by the first annular step surface 111 and the first circular step surface 110 are obtained. When only two measuring surfaces are needed, a film thickness monitoring structure having two measuring surfaces representing different film thicknesses can be formed in the same film 11.

[0067] In some embodiments, the above-mentioned method of using the first annular photoresist layer 21 as a mask to etch the surface of the film 11 exposed inside the first annular photoresist layer 21 specifically includes the following method:

[0068] First, the first photoresist after spin coating is subjected to photolithography without a photomask (ie, photolithography without a photomask), including steps of exposure, development, and hardening, to form a first annular photoresist layer 21 (patterned first photoresist).

[0069] Then, the first annular photoresist layer 21 is used as a mask to anisotropically etch the surface of the film 11 exposed inside the first annular photoresist layer 21. Thus, a circular first groove 114 is formed on the surface of the film 11 exposed inside the first annular photoresist layer 21. Figure 2 As shown in (d), the circular bottom surface of the first groove 114 is the first circular step surface 110.

[0070] In order to better achieve the purpose of the present invention, more measuring surfaces can be formed on the surface of the film 11 based on the first annular step surface 111 and the first circular step surface 110 formed as described above.

[0071] In some embodiments, the same method described above can be repeatedly used to define new photoresist spraying points on the surface of the film 11, so that the distance between each newly defined photoresist spraying point and the edge of the substrate 10 is greater than the distance between the photoresist spraying point defined last time and the edge of the substrate 10, and after each time the photoresist is spin-coated through the newly defined photoresist spraying point and correspondingly etched, a new circular step surface and a new annular step surface are formed on the circular step surface formed last time, so as to form multiple annular step surfaces whose heights are successively higher than the central circular step surface outside the circular step surface located in the center formed last time, so as to obtain a film thickness monitoring structure with at least three measuring surfaces formed by the central circular step surface and each annular step surface.

[0072] Therefore, according to Figure 2 The production process of patterning the film 11 further includes the following steps following the above steps:

[0073] like Figure 2 As shown in (d), a second photoresist spraying point 221 is defined on the first circular step surface 110, so that the second photoresist spraying point 221 is at a second distance from the edge of the substrate 10, or the second photoresist spraying point 221 is at a distance of a second spin-coating radius R2 from the center of the substrate 10. The second distance is greater than the first distance, and correspondingly, the second spin-coating radius R2 is smaller than the first spin-coating radius R1. That is, the second photoresist spraying point 221 needs to be defined to be located radially inward of the first photoresist spraying point 211, so that the photoresist sprayed through the second photoresist spraying point 221 can fall on the first circular step surface 110.

[0074] like Figure 2 As shown in (e), the second photoresist is then spin-coated starting from the second photoresist spraying point 221, and under the action of centrifugal force, the second photoresist spreads outward to cover the first circular step surface 110 and the first annular step surface 111 outside the second photoresist spraying point 221. The above-mentioned method for forming the first annular photoresist layer mask is used to form a second annular photoresist layer 22 (the photoresist pattern after photolithography without a mask) with the center of the substrate 10 as the center of the circle between the second photoresist spraying point 221 and the edge of the substrate 10.

[0075] Next, the first circular step surface 110 exposed inside the second annular photoresist layer 22 is etched using the second annular photoresist layer 22 as a mask, and a sunken second circular step surface is formed on the first circular step surface 110 inside the second annular photoresist layer 22 as the central circular step surface 113. At the same time, the remaining first circular step surface 110 outside the central circular step surface 113 forms a second annular step surface 112 with a height higher than the central circular step surface 113 and lower than the first annular step surface 111, as shown in FIG. Figure 2After removing the second annular photoresist layer 22, three measuring surfaces formed by the first annular step surface 111, the second annular step surface 112 and the central circular step surface 113 are obtained, thereby forming a film thickness monitoring structure having three measuring surfaces representing three different film thicknesses in a film 11 of the same material.

[0076] Figure 4-Figure 5 Shown according to Figure 2 A film thickness monitoring wafer structure with three measuring surfaces representing three different film thicknesses is made of a film 11 of the same material. It can be understood that according to the above method, more annular step surfaces can be continuously formed on the surface of the film 11, and finally a central circular step surface located at the innermost side. The above method can be referred to for understanding, and no further description is given.

[0077] In some embodiments, when etching is performed multiple times to form a film thickness monitoring structure having at least three measurement surfaces, the etching depth during each etching is the same, that is, the step heights between every two adjacent step surfaces are the same.

[0078] In some embodiments, when etching is performed multiple times to form a film thickness monitoring structure having at least three measurement surfaces, the etching depth during each etching may be different. Figure 5 The step height between the first annular step surface 111 and the second annular step surface 112 is greater than the step height between the second annular step surface 112 and the central circular step surface 113, indicating that the etching depth when forming the first annular step surface 111 is greater than the etching depth when forming the second annular step surface 112.

[0079] In some embodiments, the widths of the step surfaces along the radial direction of the substrate 10 are the same.

[0080] In some embodiments, the widths of the step surfaces along the radial direction of the substrate 10 are different. For example, Figure 5 In the radial direction of the substrate 10 , the width of the first annular step surface 111 , the width of the second annular step surface 112 , and the width of the central circular step surface 113 increase in sequence, but are not limited thereto.

[0081] Therefore, adopt the above-mentioned Figure 2 The method can conveniently control the masking position of the photoresist after spin coating by adjusting the position of the photoresist spraying starting point and utilizing the centrifugal force, thereby controlling the size of the region etched for the film 11, and finally controlling the number of measurement surfaces with different thicknesses formed on the film 11. Moreover, by adopting the above method of the present invention, photolithography can be realized without a photomask, thus saving the photomask cost.

[0082] refer to Figure 3The present invention provides a method for manufacturing a film thickness monitoring wafer, which uses a monitoring film 11 made of various materials to manufacture a film thickness monitoring wafer, and the manufacturing process includes the following steps:

[0083] like Figure 3 As shown in (a), a wafer substrate 10 is used to manufacture a film thickness monitoring wafer formed by a thin film 11 made of multiple materials according to the present invention.

[0084] In some embodiments, the wafer substrate 10 may be, for example, a silicon wafer substrate 10. However, the present invention is not limited thereto, and any wafer substrate 10 suitable for use as a film thickness monitoring wafer may be used, such as a germanium wafer substrate 10, a silicon carbide wafer substrate 10, and the like.

[0085] First, a monitoring thin film 11 is formed on one side of a substrate 10 .

[0086] In some embodiments, a monitoring film 11 made of multiple materials is formed on the upper surface of the substrate 10 as shown in the figure. That is, the monitoring film 11 is a multi-layer film 11 made of different materials formed on the upper surface of the substrate 10.

[0087] In some embodiments, a monitoring thin film 11 of various materials is formed on the upper surface of the substrate 10 as shown in the figure by using the same process as the corresponding thin film prepared in production. For example, the thin film preparation process in production may include at least one of CVD, PVD, ALD, etc. Then, a monitoring thin film 11 of various materials is formed on the upper surface of the substrate 10 by using the same process as the corresponding thin film prepared in production.

[0088] In some embodiments, the material of the film 11 includes a light-transmitting medium.

[0089] Furthermore, the light-transmitting medium includes silicon oxide, silicon nitride, and silicon oxynitride. However, it is understandable that the light-transmitting medium may also be other light-transmitting media that can be used for monitoring other than silicon oxide, silicon nitride, and silicon oxynitride.

[0090] like Figure 3 As shown in (a), in some embodiments, a structure of a thin film 11 having three layers of film layers of different materials is formed on the upper surface of a silicon wafer substrate 10. In this embodiment, a thin film 11 having three film layers of a silicon oxide layer 12, a silicon nitride layer 13, and a silicon oxynitride layer 14 is sequentially formed on the upper surface of a silicon wafer substrate 10.

[0091] Then, a film thickness monitoring structure is formed in the film 11 on the upper surface of the film 11 away from the substrate 10, so that the film thickness monitoring structure has a plurality of step surfaces with a decreasing height gradient arranged from the edge of the substrate 10 toward the center, and the step surfaces are used as the measuring surfaces of the film thickness monitoring structure for monitoring the film thickness measuring machine.

[0092] In some embodiments, by patterning the thin film 11 formed in the above steps, a film thickness monitoring structure located in the thin film 11 is formed on the upper surface of the thin film 11, and a concentric circle structure with the center of the substrate 10 as the center is formed between the boundaries of each step surface formed in the film thickness monitoring structure. For example, Figure 6 and Figure 7 The following is shown in Figure 3 According to the manufacturing process, three step surfaces with decreasing height gradient arranged from the edge of the substrate 10 to the center are formed on the upper surface of the film 11, which are the first annular step surface 111, the second annular step surface 112 and the central circular step surface 113. Among them, the first annular step surface 111 and the second annular step surface 112 respectively form concentric annular shapes with the center of the substrate 10 as the center, and the central circular step surface 113 forms a circle with the center of the substrate 10 as the center. As a result, the boundary between the first annular step surface 111 and the second annular step surface 112, and the boundary between the second annular step surface 112 and the central circular step surface 113 are both circular, and a concentric circle structure with the center of the substrate 10 as the center is formed. In addition, the first annular step surface 111 is located on the surface of the top silicon oxynitride layer 14, the second annular step surface 112 is located on the surface of the middle silicon nitride layer 13, and the central circular step surface 113 is located on the surface of the lower silicon oxide layer 12. That is, a step surface as a measuring surface is formed in each of the above three film layers.

[0093] In some embodiments, according to Figure 3 The film 11 is patterned by the production process, which specifically includes the following methods:

[0094] like Figure 3 As shown in (b), a first photoresist spraying point 211 is first defined on the upper surface of the silicon oxynitride layer 14, so that the first photoresist spraying point 211 is at a first distance from the edge of the substrate 10, or the first photoresist spraying point 211 is at a first spin coating radius R1 from the center of the substrate 10.

[0095] Then, the first photoresist is spin-coated on the surface of the silicon oxynitride layer 14 through the nozzle 20, with the first photoresist spraying start point 211 as the starting point for the photoresist to be sprayed on the surface of the film 11. Under the action of the centrifugal force when the substrate 10 rotates, the first photoresist is spin-coated according to the first spin-coating radius R1, so that it only covers the annular area from the outside of the first photoresist spraying start point 211 to the edge of the substrate 10, as shown in FIG. Figure 3 Thus, a first annular photoresist layer 21 with the center of the substrate 10 as the center can be formed between the first photoresist spraying point 211 and the edge of the substrate 10.

[0096] like Figure 3As shown in (c), then, using the first annular photoresist layer 21 as a mask, the surface of the silicon nitride oxide layer 14 exposed inside the first annular photoresist layer 21 is etched, and the etching stops on the surface of the silicon nitride layer 13. After etching, a first circular step surface 110 is formed on the surface of the silicon nitride layer 13 inside the first annular photoresist layer 21, and at the same time, a first annular step surface 111 having a height higher than the first circular step surface 110 is formed on the surface of the silicon nitride oxide layer 14 outside the first circular step surface 110 (i.e., the coverage area corresponding to the first annular photoresist layer 21) (refer to Figure 3 (d)). Thus, after removing the first annular photoresist layer 21, two measuring surfaces formed by the first annular step surface 111 and the first circular step surface 110 are obtained. When only two measuring surfaces are needed, a film thickness monitoring structure having two measuring surfaces representing two material film layers can be formed in the double-layer film of the silicon oxynitride layer 14 and the silicon nitride layer 13.

[0097] In some embodiments, the first annular photoresist layer 21 is used as a mask to etch the surface of the silicon oxynitride layer 14 exposed inside the first annular photoresist layer 21, specifically including the following method:

[0098] First, the first photoresist after spin coating is subjected to photolithography without a photomask (ie, photolithography without a photomask), including steps of exposure, development, and hardening, to form a first annular photoresist layer 21 (patterned first photoresist).

[0099] Then, the first annular photoresist layer 21 is used as a mask to anisotropically etch the surface of the silicon oxynitride layer 14 exposed inside the first annular photoresist layer 21. Thus, a circular first groove 114 is formed on the surface of the silicon oxynitride layer 14 exposed inside the first annular photoresist layer 21. Figure 3 As shown in (d), the circular bottom surface of the first groove 114 is located on the surface of the silicon nitride layer 13, that is, the first circular step surface 110.

[0100] In order to better achieve the purpose of the present invention, on the basis of the first annular step surface 111 and the first circular step surface 110 formed as above, Figure 3 The thin film 11 shown has three film layers and further measurement surfaces are formed on the surface.

[0101] In some embodiments, the same method described above can be repeatedly used to define new photoresist spraying points on the surface of the film 11, so that the distance between each newly defined photoresist spraying point and the edge of the substrate 10 is greater than the distance between the photoresist spraying point defined last time and the edge of the substrate 10, and after each time the photoresist is spin-coated through the newly defined photoresist spraying point and correspondingly etched, a new circular step surface and a new annular step surface are formed on the circular step surface formed last time, so as to form multiple annular step surfaces whose heights are successively higher than the central circular step surface outside the circular step surface located in the center formed last time, so as to obtain a film thickness monitoring structure with at least three measuring surfaces formed by the central circular step surface and each annular step surface.

[0102] Therefore, according to Figure 3 The production process of patterning the film 11 further includes the following steps following the above steps:

[0103] like Figure 3 As shown in (d), a second photoresist spraying point 221 is defined on the first circular step surface 110, so that the second photoresist spraying point 221 is at a second distance from the edge of the substrate 10, or the second photoresist spraying point 221 is at a distance of a second spin-coating radius R2 from the center of the substrate 10. The second distance is greater than the first distance, and correspondingly, the second spin-coating radius R2 is smaller than the first spin-coating radius R1. That is, the second photoresist spraying point 221 needs to be defined to be located radially inward of the first photoresist spraying point 211, so that the photoresist sprayed through the second photoresist spraying point 221 can fall on the first circular step surface 110.

[0104] like Figure 3 As shown in (e), the second photoresist is then spin-coated starting from the second photoresist spraying point 221, and under the action of centrifugal force, the second photoresist spreads outward to cover the first circular step surface 110 and the first annular step surface 111 outside the second photoresist spraying point 221. The above-mentioned method for forming the first annular photoresist layer mask is used to form a second annular photoresist layer 22 (the photoresist pattern after photolithography without a mask) with the center of the substrate 10 as the center of the circle between the second photoresist spraying point 221 and the edge of the substrate 10.

[0105] Next, the first circular step surface 110 (surface of the silicon nitride layer 13) exposed inside the second circular photoresist layer 22 is etched using the second circular step surface 110 as a mask, and a sunken second circular step surface is formed on the first circular step surface 110 inside the second circular photoresist layer 22 as a central circular step surface 113, which stops on the surface of the silicon oxide layer 12, and at the same time, a second circular step surface 112 having a height higher than the second circular step surface and lower than the first circular step surface 111 is formed correspondingly with the remaining first circular step surface 110 outside the second circular step surface, as shown in FIG. Figure 3After removing the second annular photoresist layer 22, three measuring surfaces formed by the first annular step surface 111, the second annular step surface 112 and the central circular step surface 113 are obtained, thereby forming a film thickness monitoring structure with three measuring surfaces representing three different materials and thicknesses.

[0106] Figure 6-Figure 7 Shown according to Figure 3 The structure of a film thickness monitoring wafer having three measuring surfaces for characterizing the film layers and thicknesses of three different materials is made of three different materials of thin films 11. It can be understood that when more than three film layers are deposited on the substrate 10, more annular step surfaces can be continuously formed on the surface of the film 11 according to the above method, and a central circular step surface located at the innermost side.

[0107] In some embodiments, the central circular step surface is located on the bottommost film in the multilayer film, and the annular step surface is located on at least each film above the bottommost film in the multilayer film. Figure 7 In the figure, the central circular step surface 113 is located on the surface of the lowest silicon oxide layer 12 in the three-layer film 11, the surface of the silicon nitride layer 13 located above the silicon oxide layer 12 has a second annular step surface 112, and the surface of the silicon nitride oxide layer 14 located above the silicon nitride layer 13 has a first annular step surface 111.

[0108] In some embodiments, the thickness of each layer of the multilayer film is the same or different. The thickness of any layer of the film can be determined according to monitoring needs.

[0109] In some embodiments, the widths of the step surfaces along the radial direction of the substrate 10 are the same or different.

[0110] It should be noted that the above Figure 3 The number of layers of the film in the embodiment is reduced from 3 to 2, that is, a double-layer film with different materials is formed. At this time, the annular step surface (the first annular step surface) is located on the upper film in the double-layer film, and the central circular step surface is located on the lower film in the double-layer film.

[0111] Therefore, adopt the above-mentioned Figure 3 The method can conveniently control the masking position of the photoresist after spin coating by adjusting the position of the photoresist spraying starting point and utilizing the centrifugal force, thereby controlling the size of the region etched for the film 11, and finally controlling the number of measurement surfaces with different thicknesses formed on the film 11. Moreover, by adopting the above method of the present invention, photolithography can be realized without a photomask, thus saving the photomask cost.

[0112] The method for manufacturing a film thickness monitoring wafer of the present invention can also use a multilayer film of various materials, and Figure 2 and Figure 3 The production process is combined to produce a film thickness monitoring wafer.

[0113] refer to Figure 8 . It is a film thickness monitoring wafer with a thin film 11 having four film layers formed on a substrate 10. The thin film 11 includes a first thin film layer 15, a second thin film layer 16, a third thin film layer 17 and a fourth thin film layer 18 arranged in sequence in a direction away from the substrate 10. Among them, the first thin film layer 15, the second thin film layer 16, and the third thin film layer 17 can be regarded as Figure 6-Figure 7 The fourth thin film layer 18 can be regarded as a film layer corresponding to the silicon oxide layer 12, the silicon nitride layer 13, and the silicon nitride oxide layer 14 in the Figure 4-Figure 5 The fourth film layer 18 has a thickness greater than that of the first film layer 15 , the second film layer 16 and / or the third film layer 17 .

[0114] In some embodiments, Figure 8 The production process of the film thickness monitoring wafer includes the following steps:

[0115] A first thin film layer 15, a second thin film layer 16, a third thin film layer 17 and a fourth thin film layer 18 made of different materials are sequentially formed on the upper surface of the substrate 10 as shown in the figure, thereby forming a thin film 11 having the above four film layers.

[0116] Then, follow Figure 2 According to the manufacturing process, three annular step surfaces with decreasing height gradient arranged from the edge of the substrate 10 to the center are first formed on the upper surface of the fourth thin film layer 18, which are the first step surface 181, the second step surface 182 and the third step surface 183 located in the fourth thin film layer 18. After the third step surface 183 is formed, the fourth thin film layer 18 is etched through and stops on the upper surface of the third thin film layer 17, that is, a transition circular step surface is formed on the upper surface of the third thin film layer 17 within the third step surface 183.

[0117] Afterwards, follow Figure 3 In the production process, the upper surface of the third thin film layer 17 (the transition circular step surface) and the upper surface of the second thin film layer 16 are etched in turn, and an annular fourth step surface 171 and a fifth step surface 161 are respectively formed on the surfaces of the third thin film layer 17 and the second thin film layer 16 below the fourth thin film layer 18, and finally, after the second thin film layer 16 is etched through, a circular sixth step surface 151, i.e., a central circular step surface, is formed on the surface of the first thin film layer 15.

[0118] Depend on Figure 8It can be seen that when the film 11 adopts a multi-layer film layer with different materials, the central circular step surface is located on the bottommost film layer (the fourth film layer 18) in the multi-layer film layer, and the annular step surface is located on at least each film layer (the first film layer 15, the second film layer 16, and the third film layer 17) above the bottommost film layer in the multi-layer film layer.

[0119] In some embodiments, each film layer above the bottom film layer in the multi-layer film layer has at least one annular step surface formed thereon. Figure 8 An annular fifth step surface 161 is formed on the surface of the second thin film layer 16, an annular fourth step surface 171 is formed on the surface of the third thin film layer 17, and three annular step surfaces, namely a first step surface 181, a second step surface 182, and a third step surface 183, are formed on the surface of the fourth thin film layer 18.

[0120] In some embodiments, at least one annular step surface is formed on the bottommost film layer in the multi-layer film layer and is located outside the central circular step surface. Figure 8 The surface of the first thin film layer 15 is further etched using the same method as described above to form at least one more annular step surface on the surface of the first thin film layer 15, and to form a central circular step surface inside the annular step surface.

[0121] In some embodiments, Figure 8 The thickness of each film layer in the thin film 11 is the same or different.

[0122] In some embodiments, Figure 8 When the fourth thin film layer 18 is etched, the etching depth is the same or different each time.

[0123] In some embodiments, Figure 8 The widths of the step surfaces in the radial direction of the substrate 10 are the same or different.

[0124] In summary, the present invention forms a monitoring film 11 on one side of a wafer substrate 10, and forms a film thickness monitoring structure located in the film 11 on the side of the film 11 away from the substrate 10, so that the film thickness monitoring structure has a plurality of step surfaces arranged from the edge of the substrate 10 toward the center and with a decreasing height gradient and serving as measuring surfaces. A film thickness monitoring structure with multiple measuring surfaces can be formed in a film 11 of one material on a film thickness monitoring wafer, or a film thickness monitoring structure with at least one measuring surface can be formed in each of multilayer films 11 of different materials, thereby ensuring the integrity of the film thickness monitoring project and reducing the machine time occupied during monitoring, thereby improving the monitoring efficiency, increasing the machine capacity, and greatly reducing the number of film thickness monitoring wafers in stock, thereby saving costs.

[0125] Although the embodiments of the present invention are described in detail above, it is obvious to those skilled in the art that various modifications and variations can be made to these embodiments. However, it should be understood that such modifications and variations are within the scope and spirit of the present invention as described in the claims. Moreover, the present invention described herein may have other embodiments and may be implemented or realized in a variety of ways.

Claims

1. A method for manufacturing a film thickness monitoring wafer, characterized in that: include: providing a wafer substrate; forming a monitoring thin film on one side of the substrate; A film thickness monitoring structure is formed in the film on a side of the film away from the substrate. The film thickness monitoring structure has a plurality of step surfaces with decreasing height gradient arranged from the edge of the substrate toward the center. The step surfaces serve as measurement surfaces.

2. The method for manufacturing a film thickness monitoring wafer according to claim 1, characterized in that: By patterning the thin film, the film thickness monitoring structure located in the thin film is formed on the surface of the film away from the substrate, and a concentric circle structure with the center of the substrate as the center is formed between the boundaries of each step surface of the film thickness monitoring structure.

3. The method for manufacturing a film thickness monitoring wafer according to claim 2, characterized in that: The patterning of the film specifically includes: defining a photoresist spraying point on the surface of the film; Spinning photoresist on the surface of the film with the photoresist spraying point as the starting point, so as to form an annular photoresist layer with the center of the substrate as the center between the photoresist spraying point and the edge of the substrate; Using the annular photoresist layer as a mask, the surface of the thin film exposed on the inner side is etched to form a sunken circular step surface on the thin film surface inside the annular photoresist layer, and a corresponding annular step surface with a height higher than the circular step surface is formed on the thin film surface outside the circular step surface, thereby obtaining the film thickness monitoring structure having the two measuring surfaces formed by the annular step surface and the circular step surface.

4. The method for manufacturing a film thickness monitoring wafer according to claim 3, characterized in that: Also includes: The same method is repeatedly used to define new photoresist spraying points on the surface of the film, so that the distance between each newly defined photoresist spraying point and the edge of the substrate is greater than the distance between the photoresist spraying point defined last time and the edge of the substrate, and each time the photoresist is spin-coated at the newly defined photoresist spraying point and etched accordingly, a new circular step surface and a new annular step surface are formed on the circular step surface formed last time, so that multiple annular step surfaces with heights successively higher than the central circular step surface are formed outside the circular step surface located in the center formed last time, so as to obtain the film thickness monitoring structure with at least three measuring surfaces formed by the central circular step surface and each annular step surface.

5. The method for manufacturing a film thickness monitoring wafer according to claim 3 or 4, characterized in that: The film is a single-layer film.

6. The method for manufacturing a film thickness monitoring wafer according to claim 3, characterized in that: The film is a double-layer film made of different materials, the annular step surface is located on the upper film in the double-layer film, and the circular step surface is located on the lower film in the double-layer film.

7. The method for manufacturing a film thickness monitoring wafer according to claim 4, characterized in that: The film is a multi-layer film made of different materials, the central circular step surface is located on the bottom layer of the multi-layer film, and the annular step surface is located on at least each layer of the film above the bottom layer of the multi-layer film.

8. The method for manufacturing a film thickness monitoring wafer according to claim 7, characterized in that: At least one annular step surface is formed on each film layer above the bottommost film layer in the multi-layer film.

9. The method for manufacturing a film thickness monitoring wafer according to claim 7, characterized in that: The bottommost film in the multi-layer film is also formed with at least one annular step surface located outside the central circular step surface.

10. The method for manufacturing a film thickness monitoring wafer according to claim 7, characterized in that: The thickness of each layer of the multilayer film is the same or different.

11. The method for manufacturing a film thickness monitoring wafer according to claim 4, characterized in that: The etching depth during each etching process may be the same or different.

12. The method for manufacturing a film thickness monitoring wafer according to claim 3, characterized in that: The method of etching the surface of the thin film exposed on the inner side by using the annular photoresist layer as a mask specifically includes: Performing photolithography without a mask on the spin-coated photoresist to form a ring-shaped photoresist layer; The annular photoresist layer is used as a mask to perform anisotropic etching on the surface of the film exposed on the inner side.

13. The method for manufacturing a film thickness monitoring wafer according to claim 1, characterized in that: The widths of the step surfaces along the radial direction of the substrate are the same or different.

14. The method for manufacturing a film thickness monitoring wafer according to claim 1, characterized in that: The material of the film includes a light-transmitting medium.

15. The method for manufacturing a film thickness monitoring wafer according to claim 14, characterized in that: The light-transmitting medium includes at least one of silicon oxide, silicon nitride, and silicon oxynitride.

16. A film thickness monitoring wafer manufactured by the method for manufacturing a film thickness monitoring wafer according to any one of claims 1 to 15.

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