Stress-controllable amorphous carbon film and method for preparing the same

Abstract

This invention belongs to the semiconductor field, specifically relating to a stress-controllable amorphous carbon film and its preparation method. The stress of the amorphous carbon film of this invention ranges from -100 to 100 MPa. This invention employs traditional PECVD thin film deposition conditions, controlling the doping ratio of deposition gases such as C2-C4 alkynes, C2-C4 alkenes, and C1-C4 alkanes to obtain amorphous carbon films with specific tensile stress, compressive stress, and neutral stress. This invention develops a method for preparing stress-controllable amorphous carbon films through deposition gas doping. This method is simple, the process is stable and controllable, and process adjustment parameters can be added, making it suitable for processes with high requirements for stress conditions.

Description

Technical Field

[0001] This invention belongs to the field of semiconductors, and specifically relates to a stress-controllable amorphous carbon film and its preparation method. Background Technology

[0002] In existing semiconductor technologies, amorphous carbon thin films can be deposited using PECVD methods with alkynes, alkenes, and alkanes such as acetylene, propylene, and methane as precursors. However, the performance of the obtained amorphous carbon thin films is limited by the inherent characteristics of a single precursor. Amorphous carbon films prepared using a single precursor typically exhibit a positive or negative stress state. If the preceding one or more processes involve compressive stress, continuing to deposit amorphous carbon films with the same stress state will exacerbate wafer warping. Furthermore, while adjusting process parameters can improve film performance for higher performance requirements, this can lead to stress exceeding controllable limits. For example, improving the Young's modulus of an amorphous carbon thin film increases stress, resulting in high-modulus performance but also introducing the technical problem of excessive stress. Therefore, there is an urgent need in this field for a stress-controllable amorphous carbon film and its preparation method. Summary of the Invention

[0003] The purpose of this invention is to provide a stress-controllable amorphous carbon film and its preparation method.

[0004] In a first aspect, the present invention provides an amorphous carbon film, wherein the stress of the amorphous carbon film is -100 to 100 MPa.

[0005] In one or more embodiments, the thickness of the amorphous carbon film is

[0006] In one or more embodiments, the strength of the amorphous carbon film is 6 to 9 GPa.

[0007] In one or more embodiments, the modulus of the amorphous carbon film is ≥60 GPa.

[0008] A second aspect of the present invention provides a method for preparing the amorphous carbon film described in the first aspect of the present invention, the method comprising the steps of: depositing an amorphous carbon film on a substrate using a deposition gas, wherein the deposition gas is selected from two or more of C2-C4 alkynes, C2-C4 alkenes, and C1-C4 alkanes.

[0009] In one or more embodiments, the deposited gas is selected from one or more of acetylene, propylene, and methane.

[0010] In one or more embodiments, the deposition gas further includes one or more of helium, argon, and nitrogen.

[0011] In one or more embodiments, the flow rate of C2-C4 alkynes is 50-800 sccm.

[0012] In one or more embodiments, the flow rate of C2-C4 olefins is 50-800 sccm.

[0013] In one or more embodiments, the flow rate of C1-C4 alkanes is 50-800 sccm.

[0014] In one or more embodiments, the deposited gas is acetylene and propylene.

[0015] In one or more embodiments, the flow rate ratio of C2-C4 alkynes to C2-C4 olefins is 1:(0.1-10).

[0016] In one or more embodiments, the flow rate of the helium gas is 100 to 1000 sccm.

[0017] In one or more embodiments, the flow rate of the argon gas is 500 to 6000 sccm.

[0018] In one or more embodiments, the flow rate of the nitrogen gas is 500 to 6000 sccm.

[0019] In one or more embodiments, the deposition pressure is 2 to 20 Torr.

[0020] In one or more embodiments, the deposition temperature is 550–700°C.

[0021] In one or more embodiments, the spacing between the deposited electrodes is 4 to 25 mm.

[0022] In one or more embodiments, the deposition time is 480–800 s.

[0023] In one or more embodiments, the deposited high-frequency radio frequency power is 1000–6000W.

[0024] In one or more embodiments, the deposited low-frequency radio frequency power is 100–2000W.

[0025] In one or more embodiments, the high frequency is 13.56 MHz.

[0026] In one or more embodiments, the low frequency is 400 kHz.

[0027] In one or more embodiments, the substrate is a wafer.

[0028] A third aspect of the present invention provides a method for preparing a wafer, the method comprising the steps of: depositing an amorphous carbon film on the wafer using a deposition gas, the deposition gas being selected from two or more of C2-C4 alkynes, C2-C4 alkenes and C1-C4 alkanes, the deposition and the deposition gas being as described in any embodiment herein.

[0029] In a fourth aspect, the present invention provides a wafer prepared using the method described in the third aspect of the present invention.

[0030] The present invention has the following beneficial effects:

[0031] (1) This invention employs traditional PECVD thin film deposition conditions, controlling the doping ratio of deposition gases such as C2-C4 alkynes (e.g., acetylene), C2-C4 olefins (e.g., propylene), and C1-C4 alkanes (e.g., methane) to obtain amorphous carbon thin films with specific tensile stress, compressive stress, and neutral stress. This invention develops a method for preparing stress-controllable amorphous carbon films through deposition gas doping. This preparation method is simple, the process is stable and controllable, and process adjustment parameters can be increased, making it suitable for processes with high requirements for stress state.

[0032] (2) According to the needs of semiconductor manufacturing process, such as the previous one or several processes are under compressive stress, when depositing amorphous carbon film, the amorphous carbon film that meets the process requirements and has tensile stress can be obtained by adjusting the doping ratio of the deposition gas, so as to neutralize the stress (the same applies to the opposite stress), and at the same time increase the adjustment space for optimizing the film performance.

[0033] (3) Some processes require amorphous carbon thin films to have high modulus. In traditional methods, increasing the modulus will increase the stress. This invention uses two or more deposition gas doping methods to obtain amorphous carbon films with near-neutral stress, controls the film stress within a certain range, and increases the modulus by adjusting process parameters, effectively solving the technical problem of increased stress caused by high modulus. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the method for preparing stress-controllable amorphous carbon films according to the present invention. Detailed Implementation

[0035] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0036] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0037] In this document, the terms “contains,” “includes,” “containing,” and similar terms encompass the meanings of “basically composed of” and “composed of.” For example, when this document discloses “A contains B and C,” “A is basically composed of B and C” and “A is composed of B and C” should be considered as having been disclosed in this document.

[0038] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0039] Unless otherwise specified, percentages refer to mass percentages and proportions refer to mass ratios in this article.

[0040] In this document, when describing embodiments or examples, it should be understood that it is not intended to limit the invention to those embodiments or examples. Rather, all alternatives, modifications, and equivalents of the methods and materials described herein are covered within the scope defined by the claims.

[0041] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0042] This invention achieves desired stress states by controlling the doping ratio of the deposition gas, enabling the fabrication of amorphous carbon films with tensile, compressive, and neutral stresses, applicable to the semiconductor technology field. Specifically, this invention employs the PECVD method, controlling the doping ratio of deposition gases such as acetylene, propylene, and methane (C2-C4 alkynes, C2-C4 olefins, and C1-C4 alkanes) to obtain amorphous carbon films with the desired stress states (including tensile, compressive, and neutral stresses). This method enhances process adjustment capabilities, enabling applications requiring multiple stress states.

[0043] In this paper, tensile stress is positive stress, compressive stress is negative stress, and neutral stress is stress close to 0 MPa. Amorphous phase films applicable to the semiconductor field are not limited to a specific stress; generally speaking, neutral stress is better because it does not change the stress state of the wafer or changes it only slightly. However, some processes require the deposition of films with specific stress states. In such cases, inventors can obtain films with different stress states by varying the doping ratio of the deposition gas to meet process requirements.

[0044] This invention provides an amorphous carbon film with a stress of -100 to 100 MPa, for example -90 MPa, -80 MPa, -75 MPa, -70 MPa, -65 MPa, -60 MPa, -55 MPa, -50 MPa, -45 MPa, -40 MPa, -35 MPa, -30 MPa, -25 MPa, -20 MPa, -15 MPa, -10 MPa, -8 MPa, -5 MPa, -3 MPa, -1 MPa, 1 MPa, 3 MPa, 5 MPa, 8 MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, 55 MPa, 60 MPa, 65 MPa, 70 MPa, 75 MPa, 80 MPa, and 90 MPa. Preferably, the stress of the amorphous carbon film is -70 to 70 MPa, -66 to 66 MPa, -66 to 30 MPa, or -66 to 22 MPa.

[0045] In some embodiments, the thickness of the amorphous carbon film is For example

[0046] In some embodiments, the strength of the amorphous carbon film is 6–9 GPa, for example, 6 GPa, 6.2 GPa, 6.4 GPa, 6.6 GPa, 6.8 GPa, 7 GPa, 7.2 GPa, 7.4 GPa, 7.6 GPa, 7.8 GPa, 8 GPa, 8.2 GPa, or 8.5 GPa. Preferably, the strength of the amorphous carbon film is 6.6–7.6 GPa.

[0047] In some embodiments, the modulus of the amorphous carbon film is ≥60 GPa, for example, 60 GPa, 61 GPa, 62 GPa, 63 GPa, 64 GPa, 65 GPa, 66 GPa, 67 GPa, 68 GPa, 69 GPa, 70 GPa, 71 GPa, 72 GPa, 73 GPa, 74 GPa, 75 GPa, or 80 GPa. Preferably, the modulus of the amorphous carbon film is 62–65 GPa. In some embodiments, the modulus of the amorphous carbon film is ≥60 GPa, and the stress of the amorphous carbon film is -70–70 MPa. Preferably, the modulus of the amorphous carbon film is 62–65 GPa, and the stress of the amorphous carbon film is -66–22 MPa.

[0048] This invention also provides a method for preparing the amorphous carbon film of this invention, the method comprising the steps of: depositing an amorphous carbon film on a substrate using a deposition gas, wherein the deposition gas is selected from two or more of C2-C4 alkynes, C2-C4 alkenes, and C1-C4 alkanes. In some embodiments, the C2-C4 alkynes are selected from one or more of acetylene, propyne, 1-butyne, and 2-butyne. In some embodiments, the C2-C4 olefins are selected from one or more of ethylene, propylene, 1-butene, and 2-butene. In some embodiments, the C1-C4 alkanes are selected from one or more of methane, ethane, propane, n-butane, and isobutane.

[0049] In some embodiments, the depositing gas is selected from one or more of acetylene, propylene, and methane; preferably, the depositing gas is acetylene and propylene.

[0050] In some embodiments, the flow rate of C2-C4 alkynes is 50-800 sccm, for example 50 sccm, 65 sccm, 80 sccm, 90 sccm, 100 sccm, 120 sccm, 130 sccm, 150 sccm, 180 sccm, 220 sccm, 280 sccm, 350 sccm, 400 sccm, 500 sccm, preferably 65-130 sccm.

[0051] In some embodiments, the flow rate of C2-C4 olefins is 50-800 sccm, for example 50 sccm, 65 sccm, 80 sccm, 90 sccm, 100 sccm, 120 sccm, 130 sccm, 150 sccm, 180 sccm, 220 sccm, 280 sccm, 350 sccm, 400 sccm, 500 sccm, preferably 65-130 sccm.

[0052] In some embodiments, the flow rate of C1-C4 alkanes is 50-800 sccm, for example 50 sccm, 65 sccm, 80 sccm, 90 sccm, 100 sccm, 120 sccm, 130 sccm, 150 sccm, 180 sccm, 220 sccm, 280 sccm, 350 sccm, 400 sccm, 500 sccm, preferably 65-130 sccm.

[0053] In some implementations, the flow ratio of C2-C4 alkynes to C2-C4 olefins is 1:(0.1-10), for example 1:0.1, 1:0.5, 1:0.8, 1:1, 1:1.5, 1:2, 1:3, 1:4, 1:5, 1:8.

[0054] In some embodiments, the deposition gas further includes one or more of helium, argon, and nitrogen.

[0055] In some embodiments, the flow rate of the helium gas is 100 to 1000 sccm, such as 200 sccm, 300 sccm, 500 sccm, 800 sccm, preferably 400 to 800 sccm.

[0056] In some embodiments, the flow rate of the argon gas is 500 to 6000 sccm, for example 800 sccm, 1000 sccm, 1200 sccm, 1500 sccm, 1800 sccm, 2500 sccm, 4000 sccm, preferably 1200 to 6000 sccm.

[0057] In some embodiments, the flow rate of the nitrogen gas is 500 to 6000 sccm, for example 800 sccm, 1000 sccm, 1200 sccm, 1500 sccm, 1800 sccm, 2500 sccm, 4000 sccm, preferably 1200 to 6000 sccm.

[0058] In some embodiments, the deposition pressure is 2 to 20 Torr, for example 2 Torr, 2.5 Torr, 3 Torr, 4 Torr, 5 Torr, 8 Torr, 10 Torr, 12 Torr, 15 Torr, preferably 2.5 to 15 Torr.

[0059] In some embodiments, the deposition temperature is 550–700°C, for example 580°C, 600°C, 620°C, 650°C, 680°C, preferably 600–700°C.

[0060] In some embodiments, the spacing between the deposited electrodes is 4 to 25 mm, for example 5 mm, 8 mm, 12 mm, 15 mm, 18 mm, 20 mm, or 23 mm, preferably 8 to 18 mm or 18 to 25 mm.

[0061] In some embodiments, the deposition time is 480–800 s, for example 500 s, 520 s, 550 s, 580 s, 600 s, 630 s, 660 s, preferably 580–666 s.

[0062] In some embodiments, the deposited high-frequency radio frequency power is 1000-6000W, for example 1500W, 2000W, 3000W, 4000W, preferably 1500-5000W.

[0063] In some embodiments, the deposited low-frequency radio frequency power is 100 to 2000W, such as 200W, 300W, 500W, 800W, 1200W, 1500W, preferably 200 to 1800W.

[0064] In some implementations, the high frequency is 13.56 MHz.

[0065] In some implementations, the low frequency is 400 kHz.

[0066] In some embodiments, the substrate is a wafer. The front side of the wafer either has no deposited thin film or already has a deposited thin film.

[0067] The present invention also provides a method for preparing a wafer, the method comprising the steps of: depositing an amorphous carbon film on the wafer using a deposition gas, wherein the deposition gas is selected from two or more of C2-C4 alkynes, C2-C4 alkenes, and C1-C4 alkanes. The deposition and the deposition gas are as described in any embodiment herein.

[0068] The present invention also provides wafers prepared using the method of the present invention.

[0069] This invention employs two or more deposition gas doping methods to obtain amorphous carbon films with near-neutral stress. By controlling the film stress within a certain range, the Young's modulus can be further increased through process parameter adjustments, reducing the impact of stress variations on the fabrication process, expanding the process adjustability, and effectively solving the problem of excessive stress caused by high modulus in existing technologies.

[0070] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. Percentages and parts are by weight unless otherwise stated.

[0071] Preparation method of amorphous carbon film

[0072] In the thin film deposition process, by introducing two or more deposition gases and selecting different doping ratios according to process requirements, amorphous carbon thin films with different stress states or high thin film properties (high modulus and low stress) are obtained under plasma excitation, realizing the controllable preparation of advanced amorphous carbon thin films and their application in semiconductor processes. Specific preparation parameters are shown in Examples 1-3.

[0073] Example 1

[0074] Acetylene and propylene are simultaneously introduced at flow rates of 100 sccm, 100 sccm, 800 sccm for He, 1200 sccm for Ar, and 1000 sccm for N2. The high-frequency radio frequency power is 1500 W, the low-frequency radio frequency power is 200 W, the deposition pressure is 2.5 torr, the deposition temperature is 600℃, the deposition time is 630 s, and the electrode spacing is 18 mm.

[0075] Example 2

[0076] Acetylene and propylene are introduced simultaneously. The flow rate of acetylene is 135 sccm, the flow rate of propylene is 65 sccm, the flow rate of He is 800 sccm, the flow rate of Ar is 1200 sccm, the flow rate of N2 is 1000 sccm, the high-frequency radio frequency power is 1500W, the low-frequency radio frequency power is 200W, the deposition pressure is 2.5 torr, the deposition temperature is 600℃, the deposition time is 580s, and the electrode spacing is 18mm.

[0077] Example 3

[0078] Acetylene and propylene are introduced simultaneously. The flow rate of acetylene is 65 sccm, the flow rate of propylene is 135 sccm, the flow rate of He is 800 sccm, the flow rate of Ar is 1200 sccm, the flow rate of N2 is 1000 sccm, the high-frequency radio frequency power is 1500W, the low-frequency radio frequency power is 200W, the deposition pressure is 2.5 torr, the deposition temperature is 600℃, the deposition time is 660s, and the electrode spacing is 18mm.

[0079] Comparative Example 1

[0080] The process was similar to that in Example 1, except that only a single deposition gas was used. Specific deposition conditions were as follows: acetylene flow rate of 200 sccm, He flow rate of 800 sccm, Ar flow rate of 1200 sccm, N2 flow rate of 1000 sccm, high-frequency RF power of 1500 W, low-frequency RF power of 200 W, deposition pressure of 2.5 torr, deposition temperature of 600℃, deposition time of 550 s, and electrode spacing of 18 mm.

[0081] Comparative Example 2

[0082] The process was similar to that in Example 1, except that only a single deposition gas was used. The specific deposition conditions were as follows: propylene flow rate of 200 sccm, He flow rate of 800 sccm, Ar flow rate of 1200 sccm, N2 flow rate of 1000 sccm, high-frequency RF power of 1500 W, low-frequency RF power of 200 W, deposition pressure of 2.5 torr, deposition temperature of 600℃, deposition time of 720 s, and electrode spacing of 18 mm.

[0083] Test case

[0084] The thickness of the amorphous carbon film was measured using a KLA film thickness gauge.

[0085] The stress of the amorphous carbon film was tested using the Zhongke Feice test bench.

[0086] The strength and modulus of the amorphous carbon film were measured using a nanoindenter. The method involved cutting a wafer with the deposited amorphous carbon film into 1x1cm cubes, measuring the surface of the amorphous carbon film using a nanoindenter, obtaining the depth of the probe indentation into the film, and then calculating the strength and modulus.

[0087] The properties of the amorphous carbon films prepared by the processes of Examples 1-3 and Comparative Examples 1-2 are shown in Table 1.

[0088] Table 1

[0089]

[0090]

[0091] The doping ratio of acetylene to propylene (i.e., the ratio of acetylene to propylene flow rate) is set as X:Y. According to the data in Table 1, the larger X is, the more positive the stress; the larger Y is, the more negative the stress. The doping ratio of acetylene to propylene can be adjusted as needed between 1:(0.1 to 10).

[0092] While increasing the modulus of traditional amorphous carbon films results in higher stress, films obtained by doping with deposition gases generally do not exhibit properties superior to those obtained with a single precursor. As shown in Comparative Examples 1 and 2, a single precursor possesses either positive or negative stress. By combining the two in a certain ratio, the stress of the film can be controlled, and maintaining modulus and strength close to those of a single precursor is considered sufficient to improve film performance. Based on the reduced stress in films prepared with deposition gas doping, the modulus can be further increased by modifying process parameters. Although increasing the modulus still involves an increase in stress, the fundamental stress of films prepared with deposition gas doping is lower than that prepared with a single deposition gas. Therefore, using doped deposition gases to prepare amorphous carbon films increases the adjustability of process parameters. Those skilled in the art can further optimize the type and flow rate ratio of the doped deposition gas to obtain films with lower stress. Based on this, films with higher modulus can be prepared by adjusting process parameters.

Claims

1. An amorphous carbon film, characterized by, The stress of the amorphous carbon film is -100 to 100 MPa.

2. The amorphous carbon film according to claim 1, wherein The amorphous carbon film has one or more of the following characteristics: The thickness of the amorphous phase carbon film is The strength of the amorphous carbon film is 6–9 GPa; The modulus of the amorphous carbon film is ≥60 GPa.

3. A method for producing the amorphous carbon film as claimed in claim 1 or 2, characterized by, The method includes the step of depositing an amorphous carbon film on a substrate using a deposition gas, wherein the deposition gas is selected from two or more of C2-C4 alkynes, C2-C4 alkenes, and C1-C4 alkanes.

4. The method of claim 3, wherein, The deposition gas is selected from one or more of acetylene, propylene, and methane; and / or, the deposition gas further includes one or more of helium, argon, and nitrogen.

5. The method of claim 3, wherein, The deposited gas has one or more of the following characteristics: The flow rate of C2-C4 alkynes is 50-800 sccm; The flow rate of C2-C4 olefins is 50-800 sccm; The flow rate of C1 to C4 alkanes is 50 to 800 sccm.

6. The method of claim 4, wherein, The deposited gas has one or more of the following characteristics: The flow rate of the helium gas is 100–1000 sccm; The flow rate of the argon gas is 500–6000 sccm; The flow rate of the nitrogen gas is 500–6000 sccm.

7. The method of claim 3, wherein, The deposition has one or more of the following characteristics: The deposition pressure is 2–20 Torr; The deposition temperature is 550–700°C; The spacing between the deposited electrodes is 4–25 mm; The deposition time is 480–800 s; The deposited high-frequency radio frequency power is 1000-6000W; The deposited low-frequency radio frequency power is 100-2000W.

8. The method according to any one of claims 3 to 7, characterized in that, The substrate is a wafer.

9. A method of preparing a wafer, characterized by, The method includes the step of depositing an amorphous carbon film on a wafer using a deposition gas, wherein the deposition gas is selected from two or more of C2-C4 alkynes, C2-C4 alkenes and C1-C4 alkanes, and the deposition and the deposition gas are as described in any one of claims 4 to 7.

10. A wafer prepared using the method of claim 9.

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