A method for manufacturing a thin film resistor

Abstract

The application provides a preparation method of a thin film resistor, comprising the following steps: forming a thin film resistor film layer on a wafer surface, and detecting the thickness of the thin film resistor film layer; adjusting the content proportion of each component in etching gas of a dry etching process according to the thickness of the thin film resistor film layer; and performing the dry etching process on the thin film resistor film layer to expose the wafer surface and obtain a thin film resistor. According to the application, the content proportion of each component in etching gas of the dry etching process is timely adjusted according to the thickness of the thin film resistor film layer, so that the cross-sectional area of the thin film resistor on each batch of wafers remains unchanged in the direction perpendicular to the length direction, thereby stabilizing the resistance value of the thin film resistor on all batches of wafers, improving the device stability of the thin film resistor, and also improving the process window of the deposition process of the thin film resistor film layer.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a method for preparing a thin-film resistor. Background Technology

[0002] In high-dielectric-constant metal gate (HKMG) processes, high-resistance thin-film resistors are required to provide resistance-based voltage division and current reduction. For example... Figure 1 As shown, the thin-film resistor 1 is disposed on the dielectric layer, and due to the instability of the PVD (physical vapor deposition) process during the formation of the thin-film resistor layer, the thickness of the thin-film resistor layer deposited in different batches of wafers varies (e.g., Figure 2 As shown in the figure, this leads to a large fluctuation in the resistance value of thin film resistors with the same linewidth obtained by subsequent etching processes of the thin film resistor layer. Summary of the Invention

[0003] The purpose of this invention is to provide a method for preparing thin-film resistors, which can improve the resistance stability of thin-film resistors.

[0004] To address the above problems, this invention provides a method for preparing a thin-film resistor, comprising the following steps:

[0005] A thin-film resistive film layer is formed on the surface of the wafer, and the thickness of the thin-film resistive film layer is measured;

[0006] The content ratio of each component in the etching gas of the dry etching process is adjusted according to the thickness of the thin-film resistive film; and

[0007] A dry etching process is performed on the thin-film resistor layer to expose the wafer surface and obtain a thin-film resistor.

[0008] Optionally, the specific method for forming the thin-film resistive layer and detecting the thickness of the thin-film resistive layer is as follows:

[0009] Provide at least one batch of wafers, the wafers comprising a substrate and a dielectric layer on the substrate;

[0010] A thin-film resistive film is deposited on the dielectric layer of each wafer using a physical vapor deposition process.

[0011] A mask layer is deposited on the thin-film resistive film layer;

[0012] In each batch, the thickness of the thin-film resistive layer on at least a portion of the wafers is measured.

[0013] Furthermore, within each batch, the thickness of the thin-film resistor layer on a portion of the wafers in each batch is tested through random sampling; or,

[0014] In each batch, the thickness of the thin-film resistor layer on all wafers in each batch is measured through a full inspection.

[0015] Furthermore, the material of the thin-film resistive layer is titanium nitride.

[0016] Furthermore, the specific method for adjusting the content ratio of each component in the etching gas of the dry etching process is as follows:

[0017] The average thickness of all thin-film resistor layers in the same batch was taken.

[0018] The content ratio of each component in the etching gas is adjusted according to the average thickness.

[0019] Furthermore, the specific method for adjusting the content ratio of each component in the dry etching gas based on the average thickness is as follows:

[0020] The content ratio of each component in the etching gas of the dry etching process is adjusted according to the linewidth of the thin film resistor.

[0021] Furthermore, the ratio of carbon content to fluorine content in the etching gas of the dry etching process is adjusted according to the linewidth of the thin film resistor.

[0022] Furthermore, the linewidth of the thin-film resistor is directly proportional to the ratio of carbon content to fluorine content in the etching gas of the dry etching process.

[0023] Furthermore, the specific method of formation is as follows:

[0024] Based on the linewidth of the thin film resistor, the mask layer is etched to form a mask pattern with a linewidth of b;

[0025] Using the mask layer as a mask, the thin film resistor layer is etched by a dry etching process to obtain a thin film resistor with a linewidth of b.

[0026] Furthermore, the mask layer is made of silicon nitride, and the dielectric layer is made of silicon oxide.

[0027] Compared with the prior art, the present invention has the following unexpected technical effects:

[0028] This invention provides a method for fabricating a thin-film resistor, comprising the following steps: forming a thin-film resistor layer on a wafer surface and detecting the thickness of the thin-film resistor layer; adjusting the content ratio of each component in the etching gas of a dry etching process according to the thickness of the thin-film resistor layer; and performing a dry etching process on the thin-film resistor layer to expose the wafer surface and obtain the thin-film resistor. This invention, by timely adjusting the content ratio of each component in the etching gas of the dry etching process according to the thickness of the thin-film resistor layer, ensures that the cross-sectional area of ​​the thin-film resistors on each batch of wafers remains constant in the direction perpendicular to the length, thereby stabilizing the resistance value of the thin-film resistors on all batches of wafers, improving the device stability of the thin-film resistor, and also improving the process window of the thin-film resistor layer deposition process. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the structure of a thin-film resistor.

[0030] Figure 2 This is a schematic diagram showing the resistance distribution of thin-film resistors from different batches of wafers.

[0031] Figure 3 This is a schematic flowchart of a method for preparing a thin-film resistor according to an embodiment of the present invention.

[0032] Figure 4 This is a three-dimensional structural diagram of a thin-film resistor provided in an embodiment of the present invention.

[0033] Figure 5 This is a schematic diagram of a thin-film resistor provided in an embodiment of the present invention.

[0034] Explanation of reference numerals in the attached figures:

[0035] Figure 1 In the middle: 1 - Thin film resistor;

[0036] Figures 4-5 In the middle: 10-substrate; 11-dielectric layer; 12-thin film resistor; 13-mask layer. Detailed Implementation

[0037] The following will provide a more detailed description of a method for preparing a thin-film resistor according to the present invention. The invention will now be described in more detail with reference to the accompanying drawings, which illustrate preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0038] For clarity, not all features of the actual embodiments are described. In the following description, well-known functions and structures are not detailed in detail, as they would obscure the invention with unnecessary detail. It should be understood that in the development of any actual embodiment, numerous implementation details must be made to achieve the developer's specific objectives, such as changes from one embodiment to another according to limitations related to the system or business. Furthermore, it should be understood that such development work may be complex and time-consuming, but is merely routine work for those skilled in the art.

[0039] To make the objectives and features of the present invention more apparent and understandable, the specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that the drawings are all in a very simplified form and use non-precise ratios, and are only used to conveniently and clearly assist in illustrating the objectives of the embodiments of the present invention.

[0040] like Figure 3 As shown, this embodiment provides a method for preparing a thin-film resistor, including the following steps:

[0041] Step S1: Form a thin film resistive layer on the wafer surface and measure the thickness of the thin film resistive layer;

[0042] Step S2: Adjust the content ratio of each component in the etching gas of the dry etching process according to the thickness of the thin film resistive film layer;

[0043] Step S3: Perform a dry etching process on the thin film resistor layer to expose the wafer surface and obtain the thin film resistor.

[0044] The following combination Figures 4-5 This embodiment provides a detailed description of a method for preparing a thin-film resistor.

[0045] First, step S1 is performed to form a thin-film resistive film layer on the wafer surface, and the thickness of the thin-film resistive film layer is detected.

[0046] This step specifically includes:

[0047] First, at least one batch of wafers is provided, with a fixed number of wafers in each batch, for example, 25 wafers.

[0048] The wafer includes a substrate 10 and a dielectric layer 11 located on the substrate 10. The substrate 10 is, for example, a silicon substrate 10, and semiconductor devices, such as high-dielectric-constant metal-gate MOS transistors, can be formed in the substrate 10. The dielectric layer 11 can be made of silicon oxide.

[0049] Next, a thin-film resistive film is deposited on the dielectric layer 11 of each wafer in each batch of wafers using a PVD (physical vapor deposition) deposition process. The material of the thin-film resistive film is titanium nitride.

[0050] Next, a mask layer 13 is deposited on the thin-film resistive film layer. The mask layer 13 includes at least a silicon nitride layer. In one embodiment, the mask layer 13 includes only a silicon nitride layer. In other embodiments, the mask layer 13 can be a mask stack structure, for example, including a silicon nitride layer and a BARC layer (i.e., a bottom anti-reflective coating) from bottom to top.

[0051] Next, in each batch, the thickness of the thin-film resistive layer on at least a portion of the wafers is measured. Specifically, an online feedback system is first established, comprising a parameter detection unit, a parameter collection and feedback unit, and a receiving and display unit. The parameter detection unit detects the thickness of the thin-film resistive layer, the parameter collection and feedback unit records the thickness of the thin-film resistive layer and feeds the data back to the receiving and display unit, which includes a terminal app and a display. The terminal app receives the data and displays it on the display. Then, the thickness of the thin-film resistive layer is fed back through the online feedback system.

[0052] In one embodiment, the thickness of the thin-film resistive layer on a subset of wafers in each batch is measured by random sampling. In another embodiment, the thickness of the thin-film resistive layer on all wafers in each batch is measured by full inspection.

[0053] Next, step S2 is performed, adjusting the content ratio of each component in the etching gas of the dry etching process according to the thickness of the thin film resistive film.

[0054] This step specifically includes:

[0055] First, the average thickness of all thin-film resistor layers in the same batch is taken.

[0056] like Figures 4-5 As shown, the content ratio of each component in the etching gas is then adjusted according to the average thickness. Specifically, the relationship between the resistance value of the thin-film resistor 12 to be formed and the dimensions of each thin-film resistor 12 is determined.

[0057] That is, since R = ρ * L / A;

[0058] A = a * b;

[0059] Where R is the resistance of the thin film resistor 12, ρ is the resistivity of the thin film resistor 12, L is the length of the thin film resistor 12, A is the cross-sectional area of ​​the thin film resistor 12 in the direction perpendicular to the length L, a is the thickness of the thin film resistor 12, and b is the linewidth of the thin film resistor 12.

[0060] It can be seen that, with the material and length of the thin-film resistor 12 remaining constant, the factors affecting the resistance value of the thin-film resistor 12 include its thickness *a* and linewidth *b*, which is the cross-sectional area *A* of the thin-film resistor 12 perpendicular to its length *L*. Therefore, given the average thickness *a* of the thin-film resistor 12, the only factor affecting its resistance value is its linewidth *b*. Furthermore, according to the above formula, when the thickness *a* of the thin-film resistor 12 is fixed, its resistance value is inversely proportional to its linewidth *b*. That is, when the average thickness is fixed, a larger linewidth *b* results in a smaller resistance value, and a smaller linewidth *b* results in a larger resistance value.

[0061] Next, the content ratio of each component in the etching gas of the dry etching process is adjusted according to the linewidth b of the thin film resistor 12. Specifically, the ratio of carbon content to fluorine content in the etching gas of the dry etching process is adjusted according to the linewidth b of the thin film resistor 12. Furthermore, the linewidth b of the thin film resistor 12 is directly proportional to the ratio of carbon content to fluorine content in the etching gas of the dry etching process.

[0062] In this embodiment, if the thickness 'a' of the thin film resistor 12 is too small, the linewidth 'b' of the thin film resistor 12 needs to be increased. In this case, the ratio of carbon content to fluorine content in the etching gas of the dry etching process needs to be increased. If the thickness 'a' of the thin film resistor 12 is too large, the linewidth 'b' of the thin film resistor 12 needs to be decreased. In this case, the ratio of carbon content to fluorine content in the etching gas of the dry etching process needs to be decreased.

[0063] Please continue reading. Figure 5 Next, step S3 is performed to perform a dry etching process on the thin film resistor layer to expose the wafer surface and obtain the thin film resistor 12.

[0064] First, the mask layer 13 is etched according to the linewidth b of the thin film resistor 12 to form a mask pattern with a linewidth b.

[0065] Next, using the mask layer 13 as a mask, the thin film resistor layer is etched by a dry etching process to obtain a thin film resistor 12 with a linewidth of b.

[0066] In this step, the proportion of each component in the etching gas in the dry etching process is adjusted in a timely manner according to the required linewidth b of the thin film resistor 12. This ensures that the cross-sectional area A of the thin film resistor 12 on each batch of wafers remains unchanged in the direction perpendicular to the length, thereby stabilizing the resistance value of the thin film resistor 12 on all batches of wafers, improving the device stability of the thin film resistor 12, and also improving the process window of the thin film resistor film deposition process.

[0067] In summary, this invention provides a method for fabricating a thin-film resistor, comprising the following steps: forming a thin-film resistor layer on a wafer surface and detecting the thickness of the thin-film resistor layer; adjusting the content ratio of each component in the etching gas of a dry etching process according to the thickness of the thin-film resistor layer; and performing a dry etching process on the thin-film resistor layer to expose the wafer surface and obtain the thin-film resistor. This invention, by timely adjusting the content ratio of each component in the etching gas of the dry etching process according to the thickness of the thin-film resistor layer, ensures that the cross-sectional area of ​​the thin-film resistors on each batch of wafers remains constant in the direction perpendicular to the length, thereby stabilizing the resistance value of the thin-film resistors on all batches of wafers, improving the device stability of the thin-film resistor, and also improving the process window of the thin-film resistor layer deposition process.

[0068] Furthermore, it should be noted that, unless otherwise specified or indicated, the terms "first" and "second" in the specification are used only to distinguish the various components, elements, steps, etc. in the specification, and are not used to indicate the logical or sequential relationships between the various components, elements, steps, etc.

[0069] It is understood that although the present invention has been disclosed above with reference to preferred embodiments, these embodiments are not intended to limit the present invention. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of the present invention based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing a thin-film resistor, characterized in that, Includes the following steps: A thin-film resistive film layer is formed on the surface of the wafer, and the thickness of the thin-film resistive film layer is measured; The average thickness of all thin-film resistor layers in the same batch was taken. The ratio of carbon content to fluorine content in the etching gas of the dry etching process is adjusted according to the linewidth of the thin-film resistor, wherein the linewidth b of the thin-film resistor is directly proportional to the ratio of carbon content to fluorine content in the etching gas of the dry etching process; and A dry etching process is performed on the thin-film resistor layer to expose the wafer surface and obtain the thin-film resistor; If the thickness of the thin-film resistor layer is too small, the linewidth of the thin-film resistor is increased by increasing the ratio of carbon content to fluorine content; if the thickness of the thin-film resistor layer is too large, the linewidth of the thin-film resistor is decreased by decreasing the ratio of carbon content to fluorine content, thereby stabilizing the resistance value of the thin-film resistor.

2. The method for preparing a thin-film resistor as described in claim 1, characterized in that, The specific method for forming a thin-film resistive layer and detecting the thickness of the thin-film resistive layer is as follows: Provide at least one batch of wafers, the wafers comprising a substrate and a dielectric layer on the substrate; A thin-film resistive film is deposited on the dielectric layer of each wafer using a physical vapor deposition process. A mask layer is deposited on the thin-film resistive film layer; In each batch, the thickness of the thin-film resistive layer on at least a portion of the wafers is measured.

3. The method for preparing a thin-film resistor as described in claim 2, characterized in that, In each batch, the thickness of the thin-film resistor layer on all wafers in each batch is measured through a full inspection.

4. The method for preparing a thin-film resistor as described in claim 2, characterized in that, The material of the thin-film resistive layer is titanium nitride.

5. The method for preparing a thin-film resistor as described in claim 2, characterized in that, The specific method of formation is as follows: Based on the linewidth b of the thin film resistor, the mask layer is etched to form a mask pattern with a linewidth b; Using the mask layer as a mask, the thin film resistor layer is etched by a dry etching process to obtain a thin film resistor with a linewidth of b.

6. The method for preparing a thin-film resistor as described in claim 2, characterized in that, The mask layer is made of silicon nitride, and the dielectric layer is made of silicon oxide.

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