SiN deep hole structure forming method, readable storage medium and semiconductor processing equipment

Abstract

The invention discloses a SiN deep hole structure forming method, a readable storage medium and semiconductor processing equipment. The forming method comprises the following steps: a first etching step: first etching gas is introduced, a SiN layer is etched to form a deep hole structure, and the deep hole structure is divided into a first part and a second part according to the depth; the first part has a vertical profile, and the second part has an inverted conical profile; and a second etching step: introducing a second etching gas, and etching the deep hole structure to the barrier layer at the bottom of the deep hole structure. According to the method, a two-step method is adopted, the vertical contour is formed on the first part of the SiN deep hole structure in the first etching step, and the bottom morphology of the second part of the deep hole structure is improved in the second etching step until the whole contour of the deep hole structure is basically vertical. Moreover, the average etching rate is high, and the loss of the barrier layer is small.

Description

Technical Field

[0001] The present invention relates to the field of semiconductors, and in particular to a method for forming a SiN deep hole structure, a readable storage medium and semiconductor processing equipment. Background Art

[0002] In the field of semiconductor technology, with the surge in demand for high-density memory devices, the process technology of high aspect ratio feature size has become increasingly important. 2 ) material single layer or silicon oxide / silicon nitride (Si 3 N 4 There are many studies on the formation of high aspect ratio through-hole structures by etching SiN (hereinafter referred to as SiN) stacks. However, there are few studies on etching SiN single-layer materials to form SiN deep hole structures.

[0003] In the process of etching the SiN material layer to form a SiN deep hole structure, some methods use a one-step method of mixed etching gas, and other methods use a two-step method, respectively introducing a single gas for etching. However, these methods all have the following problems: 1) It is difficult to form the vertical profile required by the process; 2) The etching rate is slow and the time cost is high; 3) The critical size of the feature structure is unnecessarily enlarged. Summary of the invention

[0004] An object of the present invention is to solve the problem that the profile of the SiN deep hole structure is not vertical enough, and to provide a processing method. Through at least two steps, the first etching step forms a vertical profile in the first part of the SiN deep hole structure, and forms an inverted cone profile in the second part of the SiN deep hole structure. The second etching step improves the bottom morphology of the second part of the SiN deep hole structure to obtain a deep hole structure with an overall vertical profile.

[0005] In order to achieve the above object, the present invention provides a method for forming a SiN deep hole structure, comprising:

[0006] Providing a substrate, the substrate comprising a barrier layer disposed on a substrate and a SiN layer disposed on the barrier layer;

[0007] The first etching step: introducing a first etching gas to etch the SiN layer to form a deep hole structure, wherein the deep hole structure is divided into a first part and a second part according to the depth; wherein the first part has a vertical profile, and the second part has an inverted cone profile; the first etching gas contains carbon fluorine gas, carbon hydrogen fluorine gas, oxygen and dilution gas; the side wall of the inverted cone profile has a first angle with the axis of the deep hole structure;

[0008] The second etching step: introducing a second etching gas to etch the deep hole structure to the barrier layer at the bottom of the deep hole structure, and making the contour side wall of the second part and the axis of the deep hole structure have a second angle, and the second angle is smaller than the first angle; the second etching gas contains CH 4 , carbon fluorine gas, carbon hydrofluorine gas, oxygen.

[0009] Optionally, the general formula of the carbon fluorine gas is C x1 F y1 , 5>x1>0, y1>0.

[0010] Optionally, the carbon fluorine gas comprises C 4 F 6 , C 4 F 8 , C x F y At least one of , where 0<x≤3, y>0.

[0011] Optionally, when the carbon fluorine gas is mainly C 4 F 6 When the carbon fluorine gas is mainly the C 4 F 8 When the carbon fluorine gas is mainly the C x F y When the carbon-fluorine gas has a third proportion in the first etching gas; the first proportion is smaller than the second proportion, which is smaller than the third proportion.

[0012] Optionally, when the carbon fluorine gas is mainly C 4 F 6 When the oxygen gas is mainly the C 4 F 8 When the oxygen gas has a fifth proportion in the first etching gas; when the carbon fluorine gas is mainly the C x F y When the oxygen gas has a sixth proportion in the first etching gas; the fourth proportion is greater than the fifth proportion which is greater than the sixth proportion.

[0013] Optionally, the general formula of the carbon, hydrogen and fluorine gas is C x2 H y2 F z2 , 5>x2>0, y2>0, Z2>0.

[0014] Optionally, the hydrocarbon fluorine gas comprises CH 2 F 2, CHF 3 , CH 3 At least one of F.

[0015] Optionally, when the hydrocarbon fluorine gas is mainly CHF 3 When the carbon-hydrogen-fluorine gas is mainly CH 2 F 2 When the carbon-hydrogen-fluorine gas has an eighth proportion in the first etching gas; when the carbon-hydrogen-fluorine gas is mainly CH 3 F, the carbon-hydrogen-fluorine gas has a ninth proportion in the first etching gas; the seventh proportion is greater than the eighth proportion, which is greater than the ninth proportion.

[0016] Optionally, the dilution gas comprises N 2 , at least one of inert gas and CO.

[0017] Optionally, in the first etching gas, the ratio of carbon fluorine gas:carbon hydrogen fluorine gas:oxygen:dilution gas is 1:(1.5-2.5):(1.5-2.3):(3.5-10).

[0018] Optionally, in the first etching step, the flow rate of oxygen is dynamically reduced to enhance sidewall protection of the deep hole structure.

[0019] Optionally, in the first etching step, the flow rate of oxygen is dynamically increased to maintain the critical dimension of the first portion.

[0020] Optionally, in the first etching step, source RF power and / or bias RF power are applied, wherein the source RF power is 200W-900W and the bias RF power is 100W-1200W.

[0021] Optionally, a proportion of the carbon, hydrogen, fluorine gas in the second etching gas is greater than a proportion of the carbon, hydrogen, fluorine gas in the first etching gas.

[0022] Optionally, in the second etching step, the flow rate of oxygen is dynamically reduced to enhance sidewall protection of the first portion.

[0023] Optionally, in the second etching step, the flow rate of oxygen is dynamically increased to increase the etching rate of the second portion.

[0024] Optionally, in the second etching step, source RF power and / or bias RF power are applied, wherein the source RF power is 200W-900W and the bias RF power is 100W-1200W.

[0025] Optionally, in the deep hole structure, the depth of the first part accounts for 50% to 90% of the total depth of the deep hole structure.

[0026] Optionally, the depth-to-width ratio of the deep hole structure is greater than 5:1.

[0027] Optionally, the first etching step includes a first sub-step and a second sub-step, and the ratio of the carbon fluorine gas to the carbon hydrofluorine gas in the second sub-step is greater than the ratio of the carbon fluorine gas to the carbon hydrofluorine gas in the first sub-step.

[0028] Optionally, the second etching step includes a third sub-step and a fourth sub-step, and the ratio of the carbon fluorine gas to the carbon hydrofluorine gas in the fourth sub-step is greater than the ratio of the carbon fluorine gas to the carbon hydrofluorine gas in the third sub-step.

[0029] Optionally, the process time of the first etching step is longer than the process time of the second etching step.

[0030] The present invention also provides a readable storage medium, on which a program or instruction is stored, and when the program or instruction is executed by a processor, the method for forming the SiN deep hole structure as described above is implemented.

[0031] The present invention also provides a semiconductor processing device, comprising: a processor, a memory, and a program or instruction stored in the memory and executable on the processor, wherein the program or instruction implements the above-mentioned method for forming a SiN deep hole structure when executed by the processor.

[0032] Compared with the prior art, the technical solution of the present invention has at least the following beneficial effects:

[0033] 1) A two-step method is adopted: in the first etching step, a specific first etching gas is used to quickly etch to form a vertical first part and a second part with an inverted cone profile, and the side wall of the second part has a first angle with the axis of the deep hole structure. In the second etching step, a specific second etching gas is used to effectively reduce the first angle of the second part, improve the morphology of the second part, and obtain a deep hole structure with a substantially vertical overall profile.

[0034] 2) The first etching gas can also protect the sidewall of the first part by adjusting the ratio of gas components, and effectively control the critical dimension of the first part to prevent it from expanding. The second etching gas can also improve the selectivity of SiN and avoid the loss of the barrier layer.

[0035] 3) The process time of the first etching step is longer than the process time of the second etching step, so as to increase the etching rate and reduce the total process time.

[0036] 4) The first etching step can be divided into multiple sub-steps, and by setting different gas ratios in each sub-step, rapid etching is achieved to obtain the first part with a vertical profile and maintain the vertical morphology of the deep hole. The second etching step can also be divided into multiple sub-steps, and by setting the gas ratios of different sub-steps, the second part with a vertical profile is obtained and the loss of the barrier layer is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The present invention is a flow chart of a method for forming a SiN deep hole structure.

[0038] Figure 2 The figure is a schematic diagram of the structure of a substrate suitable for the present invention.

[0039] Figure 3 Schematic diagram of the local state of the SiN deep hole structure after the first etching step.

[0040] Figure 4 Schematic diagram of the local state of the SiN deep hole structure after the second etching step.

[0041] Figure 5 Schematic diagram of electron microscope scanning comparison of SiN deep hole structures formed in the embodiment and the comparative example.

[0042] Figure 6 Schematic diagram of electron microscope scanning comparison of single-step etching and double-step etching of SiN deep hole structure in the embodiment.

[0043] Figure ID:

[0044] Substrate 10

[0045] Barrier layer 20

[0046] SiN layer 30

[0047] Mask layer 40

[0048] Opening pattern 50

[0049] Part 151

[0050] Part 252

[0051] The central axis L of the SiN deep hole structure

[0052] Auxiliary line L' parallel to the central axis L

[0053] The first angle α

[0054] The second angle β. DETAILED DESCRIPTION

[0055] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only 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.

[0056] In the description of the present invention, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0057] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] The present invention finds that it is difficult to obtain a vertical profile in the process of etching a SiN material layer to form a deep hole structure, and the bond energy of the Si-N bond in SiN is weaker than that of the Si-O bond in silicon oxide. Therefore, in plasma etching, one of the main factors affecting the etching rate of silicon oxide is the intensity of physical bombardment, while the decisive factor for the etching rate of SiN is the chemical reaction rate on the surface of the SiN layer. The chemical reaction rate is isotropic, so it is not easy to obtain a vertical profile in the SiN etching process by controlling the bombardment direction by bias voltage like etching a silicon oxide layer. On the other hand, the SiN etching process usually uses hydrocarbon fluorine gas, and the polymers produced by the hydrocarbon fluorine gas in the etching process are deposited on the side walls of the deep hole structure and are not easy to desorb, which also affects the formation of the vertical profile in the SiN deep hole structure.

[0059] To this end, the present invention is designed to perform etching through a two-step method: in the first etching step, a first etching gas is introduced, and its vertical etching rate is relatively fast, so that a vertical profile is formed in the first part of the deep hole structure (i.e., the upper part close to the deep hole opening) and the key size of the first part is effectively controlled. At this time, the second part of the deep hole structure (i.e., the lower part away from the deep hole opening) forms an inverted cone profile; in the second etching step, a second etching gas is introduced, which forms sidewall protection for the first part and etches the second part, thereby improving the bottom morphology of the deep hole structure and improving the overall vertical profile of the deep hole structure.

[0060] like Figure 1 As shown, the method for forming the SiN deep hole structure of the present invention comprises:

[0061] In step S1, a substrate is provided, wherein the substrate comprises a barrier layer disposed on a substrate and a SiN layer disposed on the barrier layer.

[0062] It can be understood that the substrate further includes a mask layer disposed on the surface of the SiN layer, and the mask layer defines a pattern of a deep hole structure. Figure 2 This is an example of a substrate suitable for the present invention and is not intended to be limiting. Figure 2 As shown, the substrate comprises a barrier layer 20, a SiN layer 30, and a mask layer 40 which are sequentially stacked on a substrate 10, and the mask layer defines an opening pattern 50 of a SiN deep hole structure. The forming method of the present invention is to transfer the opening pattern 50 to the SiN layer to form a SiN deep hole.

[0063] The mask layer 40 serves as an etching protection mask. The SiN layer 30 has a high selective etching ratio relative to the mask layer 40 . The material of the mask layer 40 can be designed according to this principle. For example, it can be TiN or SiCN, etc., which is not limited here.

[0064] The SiN layer 30 has a high selective etching ratio relative to the barrier layer 20 to avoid loss of the barrier layer 20 when forming the SiN deep hole structure. As an example, the barrier layer 20 may be a silicon oxide layer OX such as a silicon oxide layer.

[0065] Step S2, a first etching step: introducing a first etching gas to etch the SiN layer to form a deep hole structure, wherein the deep hole structure is divided into a first part and a second part according to depth; wherein the first part has a vertical profile, and the second part has an inverted cone profile; the first etching gas contains carbon fluorine gas, carbon hydrogen fluorine gas, oxygen and dilution gas; and the side wall of the inverted cone profile has a first angle with the axis of the deep hole structure.

[0066] like Figure 3As shown, it is a schematic diagram of the local state of the SiN deep hole structure after the first etching step. The first part 51 has a vertical profile, and the top critical dimension (TCD) of the first part 51 is roughly equivalent to the bottom critical dimension (BCD) of the first part 51. That is to say, the side wall of the first part 51 is almost parallel to the central axis L of the SiN deep hole structure (i.e., the opening pattern 50), and there is no angle. In the first etching step, the SiN deep hole is etched by the first etching gas, so that the vertical etching rate is faster. Due to the composition of the first etching gas, the etching is biased to anisotropy, and the presence of a deposition layer on the hole wall causes the bottom etching size to be concentrated in the middle. That is, the critical dimension close to the first part 51 (i.e., the TCD of the second part 52) ​​is larger, and the critical dimension of the second part 52 gradually decreases along the direction toward the barrier layer 20. The extension line of the side wall of the second part 52 forms a first angle α with the central axis L of the SiN deep hole structure, and the first angle α is generally an acute angle, as an example, it can be less than 30°.

[0067] The first etching gas is used to quickly etch and transfer the opening pattern 50 to the SiN layer 30 to form the first part 51 and the second part 52. It is required to keep the outline of the first part 51 vertical while controlling the critical dimension of the first part 51 as much as possible to avoid expansion. On the other hand, it is also expected that the first angle α of the second part 52 is as small as possible, which can reduce the processing time and processing difficulty of the second etching step.

[0068] The general formula of the carbon fluorine gas is C x1 F y1 , 5>x1>0, y1>0. As an example, the carbon fluorine gas comprises C 4 F 6 , C 4 F 8 , C x F y At least one of , where 0<x≤3, y>0.

[0069] When the carbon fluorine gas is mainly C 4 F 6 When the carbon fluorine gas is mainly the C 4 F 8 When the carbon fluorine gas is mainly the C x F y When the carbon-fluorine gas has a third proportion in the first etching gas; the first proportion is less than the second proportion, which is less than the third proportion. Here, "mainly" means that the gas accounts for more than 50% of the carbon-fluorine gas by volume.

[0070] When the carbon fluorine gas is mainly C 4 F 6 When the oxygen gas is mainly the C 4 F 8 When the oxygen gas has a fifth proportion in the first etching gas; when the carbon fluorine gas is mainly the C x F y When the oxygen gas has the sixth proportion in the first etching gas, the fourth proportion is greater than the fifth proportion, which is greater than the sixth proportion. Here, "mainly" means that the gas accounts for more than 50% of the carbon-fluorine gas by volume.

[0071] The general formula of the carbon, hydrogen and fluorine gas is C x2 H y2 F z2 , 5>x2>0, y2>0, Z2>0. As an example, the hydrocarbon-fluorine gas comprises CH 2 F 2 , CHF 3 , CH 3 At least one of F.

[0072] When the hydrocarbon-fluorine gas is mainly CHF 3 When the carbon-hydrogen-fluorine gas is mainly CH 2 F 2 When the carbon-hydrogen-fluorine gas has an eighth proportion in the first etching gas; when the carbon-hydrogen-fluorine gas is mainly CH 3 F, the carbon-hydrogen-fluorine gas has a ninth proportion in the first etching gas; the seventh proportion is greater than the eighth proportion which is greater than the ninth proportion. Here, "mainly" means that the gas accounts for more than 50% of the carbon-hydrogen-fluorine gas by volume. By selecting the composition and proportion of the carbon-hydrogen-fluorine gas, the first etching gas can form a protective layer on the pore wall while maintaining a faster etching rate to prevent the pore diameter from expanding; at the same time, it can prevent the protective layer from being too thick, resulting in pore blockage or reduction of the critical dimension, which affects the bottom etching.

[0073] The diluent gas comprises N 2 , at least one of an inert gas and CO. The inert gas may be argon (Ar), krypton (Kr), xenon (Xe), or helium (He).

[0074] In the first etching gas, the ratio of carbon fluorine gas:carbon hydrogen fluorine gas:oxygen:dilution gas is 1:(1.5-2.5):(1.5-2.3):(3.5-10).

[0075] In the first etching gas, by increasing the proportion of oxygen, the critical dimensions of the deep hole structure can be maintained so that it keeps a vertical profile, and by reducing the proportion of oxygen, the protection of the sidewalls of the deep hole structure can be enhanced to prevent it from being over-etched to form a bowing structure.

[0076] In some embodiments, in order to enhance the sidewall protection of the deep hole structure, the flow rate of oxygen can be dynamically reduced in the first etching step, that is, as the etching proceeds, the flow rate of oxygen can be linearly or nonlinearly reduced, and can be specifically adjusted according to the profile state of the monitored first portion 51.

[0077] In some embodiments, in order to maintain the critical dimension of the first portion 51, the flow rate of oxygen can be dynamically increased in the first etching step to suppress excessive deposition of the sidewall protection layer, avoid aperture shrinkage, and affect subsequent etching. That is, as the etching proceeds, the flow rate of oxygen increases linearly or nonlinearly, and can be adjusted specifically according to the profile state of the monitored first portion 51.

[0078] In the first etching step, source RF power and / or bias RF power are applied, and the key dimensions and contours of the deep hole structure are controlled by adjusting the RF power. For example, when the bias RF power is high, the first etching gas easily enters the bottom of the second portion 52 for etching, and when the bias RF power is low, it is conducive to the generation of polymer to form protection on the side wall of the first portion 51. The source RF power is 200W-900W, and the bias RF power is 100W-1200W.

[0079] The first etching step includes a first sub-step and a second sub-step, and the ratio of the carbon fluorine gas to the carbon hydrofluorine gas in the second sub-step is greater than the ratio of the carbon fluorine gas to the carbon hydrofluorine gas in the first sub-step. In this way, as the first etching step proceeds, the first etching gas can protect the sidewalls of the first part that has formed a vertical profile while continuing to etch in the depth direction, thereby preventing its critical dimensions from further expanding. It can be understood that the first etching step can also be divided into more sub-steps, and by adjusting the gas ratio in each sub-step, it is possible to avoid the etching of the second part 52 being stopped too early, ensuring that the first part 51 maintains a smaller critical dimension, and forming sidewall protection in the first part 51, thereby preventing the first part 51 from causing an arched profile in the subsequent second etching step. Furthermore, a mixed gas can be used in some sub-steps, and a single component (pure gas) in the first etching gas can be introduced in some sub-steps according to the profile of the deep hole structure for processing, thereby achieving the purpose of fine-tuning.

[0080] After the first etching step, in the deep hole structure, the depth of the first portion 51 accounts for 50% to 90% of the total depth of the deep hole structure.

[0081] As an example, the first etching gas may be C 4 F 8 / CH 2 F 2 / O 2 / diluent gas (N 2 / inert gas / CO). Among them, C 4 F 8 , CH 2 F 2 , O 2 The flow rates of the dilution gas are 15-40sccm, 20-70sccm, 30-60sccm and 0-400sccm respectively. The RF power of 60MHz is 200W-900W, and the RF power of 2MHz is 100W-1200W. The temperature of the lower electrode is 20-90℃, and the pressure is 10-50mTorr.

[0082] Step S3, second etching step: introducing a second etching gas to etch the deep hole structure to the barrier layer at the bottom of the deep hole structure, and making the contour side wall of the second part have a second angle with the axis of the deep hole structure, wherein the second angle is smaller than the first angle; the second etching gas contains CH 4 , carbon fluorine gas, carbon hydrofluorine gas, oxygen.

[0083] After the second etching step, the local state of the SiN deep hole structure is as follows: Figure 4 As shown. The extension line of the side wall of the second part 52 forms a second angle β with the central axis L of the SiN deep hole structure. Since the side wall of the second part 52 is nearly parallel to the central axis L at this time, the angle between the extension line of the side wall of the second part 52 and the central axis L cannot be shown in the figure, so the angle between the auxiliary line L' parallel to the central axis L and the side wall of the second part 52 is shown as the second angle β, which is smaller than the first angle α. After the second etching step of the present invention, the second angle β is close to 0°, that is, the profile of the second part is basically vertical.

[0084] The second etching gas has a higher selectivity for the SiN relative to the barrier layer 20, so as to effectively reduce the loss of the barrier layer 20. The proportion of the carbon, hydrogen and fluorine gas in the second etching gas is greater than the proportion of the carbon, hydrogen and fluorine gas in the first etching gas.

[0085] In the second etching step, the flow rate of oxygen gas may be dynamically reduced to enhance the sidewall protection of the first portion 51 .

[0086] In the second etching step, the etching rate of the second portion 52 may be increased by dynamically increasing the flow rate of oxygen.

[0087] In the second etching step, source RF power and / or bias RF power are also applied, wherein the source RF power is 200W-900W, and the bias RF power is 100W-1200W.

[0088] The second etching step includes a third sub-step and a fourth sub-step, and the ratio of the carbon fluorine gas to the carbon hydrofluorine gas in the fourth sub-step is greater than the ratio of the carbon fluorine gas to the carbon hydrofluorine gas in the third sub-step. It can be understood that the second etching step can be further divided into more sub-steps, and the gas ratio, RF power and / or etching time are adjusted in different sub-steps to keep the profile of the first part 51 vertical without enlarging the critical dimension, reduce the second angle β, and reduce the loss of the barrier layer 20.

[0089] As an example, the second etching step uses CH 4 / CF 4 / CH 2 F 2 / O 2 / diluent gas (N 2 / inert gas / CO) as the second etching gas. Among them, CH 4 CF 4 , CH 2 F 2 , O 2 and inert gas / N 2 The flow rates are 0-80 sccm, 10-50 sccm, 10-70 sccm, 20-60 sccm and 0-400 sccm. Preferably, in the second etching step, no diluent gas is used to avoid the formation of a bow-shaped structure on the sidewall of the deep hole structure.

[0090] The process time of the first etching step is longer than the process time of the second etching step. By increasing the process time of the first etching step, the verticality of the profile of the first portion 51 can be ensured and the critical dimension can be controlled. The process time of the second etching step can be adjusted according to the difference between the TCD of the first portion 51 and the BCD of the second portion 52 after the first etching step.

[0091] Example

[0092] Will be like Figure 2 The substrate shown is placed in a processing chamber of a plasma processing device, the lower electrode temperature is 70° C., and the pressure is 25 mTorr.

[0093] A first etching gas is introduced into the processing chamber to perform a first etching step on the substrate, wherein the first etching gas is C 4 F 8 / CH 2 F 2 / O2 / diluent gas (N 2 / inert gas / CO)=1:1.6:1.9:10, source RF (60MHz) power is 500W, bias RF (2MHz) power is 600W, and time is 25s.

[0094] A second etching gas is introduced into the processing chamber to perform a second etching step on the substrate, wherein the second etching gas is CH 4 / CF 4 / CH 2 F 2 / O 2 / diluent gas (N 2 / inert gas / CO) = 1:1:3:2:8. The source RF (60MHz) power is 500W, the bias RF (2MHz) power is 500W, and the time is 20s. The electron microscope scanning image after treatment is as follows Figure 5 As shown in b.

[0095] Comparative Example

[0096] The same method as in the embodiment is used, except that the ratio of etching gas is different. In the comparative example, the first etching gas is C 4 F 8 / CH 2 F 2 / O 2 / diluent gas (N 2 / inert gas / CO) = 1:2.0:1.5:10; the second etching gas is CH 4 / CF 4 / CH 2 F 2 / O 2 / diluent gas (N 2 / inert gas / CO) = 1:6:6:40:14. The electron microscope scanning image after treatment is as follows Figure 5 As shown in a.

[0097] It can be seen that after the etching gas ratio is optimized ( Figure 5 b), the SiN hole has no bow-shaped structure, the bottom CD is significantly increased, and the overall CD of the deep hole structure does not significantly expand outward, a vertical profile is obtained, and the over-etching of the barrier layer is small. Figure 5 In a), the profile of the SiN deep hole has a bow-shaped outward expansion structure, and the bottom CD is small, resulting in the overall profile being non-vertical and a large amount of over-etching of the barrier layer.

[0098] In addition, based on Figure 6 As you can see, Figure 6 (a) is a scanning electron microscope image of deep hole etching completed only based on the first etching step, Figure 6(b) is a scanning electron microscope image of deep hole etching completed only based on the second etching step, Figure 6 (c) is a scanning electron microscope image of deep hole etching completed by double-step etching based on the embodiment.

[0099] It can be seen that it is difficult to form a deep hole etching morphology with a better vertical profile formed by double-step etching as in the embodiment based only on the first etching step or only on the second etching step. The bottom CD based only on the first etching step is small, and there is a lot of over-etching; the overall CD of the deep hole based only on the second etching step is enlarged (refer to the top mask CD), the sidewall morphology is irregular, and the whole is arched and concave.

[0100] In addition, the average etching rate of the two steps is ∼3.5 nm / s, which is much higher than the etching rate of the two-step single-gas etching method.

[0101] Since the SiN deep hole structure with a high aspect ratio is more likely to have a problem of not being vertical enough, the present invention uses the method of forming a deep hole structure with a high aspect ratio as an example, but is not limiting. It can be understood that the method of the present invention can also achieve a vertical profile for a general SiN deep hole. The high aspect ratio mentioned herein refers to an aspect ratio greater than 5:1.

[0102] The present invention also provides a readable storage medium, on which a program or instruction is stored, and when the program or instruction is executed by a processor, the method for forming the SiN deep hole structure as described above is implemented.

[0103] The present invention also provides a semiconductor processing device, comprising: a processor, a memory, and a program or instruction stored in the memory and executable on the processor, wherein the program or instruction implements the above-mentioned method for forming a SiN deep hole structure when executed by the processor.

[0104] In summary, the present invention adopts a two-step method to form a SiN deep hole structure. In the first etching step, a specific first etching gas is used to quickly etch to form a vertical first part and a second part with an inverted cone profile, and the side wall of the second part has a first angle with the axis of the deep hole structure; in the second etching step, a specific second etching gas is used to effectively reduce the first angle of the second part, improve the morphology of the second part, and obtain a deep hole structure with a substantially vertical overall profile. Furthermore, by splitting the first etching step into multiple sub-steps, different gas ratios are set in each sub-step to quickly etch the first part with a vertical profile and maintain the vertical morphology of the deep hole; the second etching step is split into multiple sub-steps, and the gas ratios of different sub-steps are set to obtain the second part with a vertical profile and reduce the loss of the barrier layer.

[0105] It should be noted that, through the process method of the present invention, in the SiN deep hole etching, the vertical morphology deep hole etching of SiN can be achieved by setting the first etching gas and the second etching gas components, and the etching of the barrier layer is suppressed. Compared with some existing technologies that claim that a protective layer deposition step needs to be added separately to the etching step to maintain the morphology, the process continuity is significantly improved and the process steps are reduced.

[0106] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it will be apparent to those skilled in the art that various modifications and substitutions of the present invention will occur. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A method for forming a SiN deep hole structure, It is characterized in that include: Providing a substrate, the substrate comprising a barrier layer disposed on a substrate and a SiN layer disposed on the barrier layer; The first etching step: introducing a first etching gas to etch the SiN layer to form a deep hole structure, wherein the deep hole structure is divided into a first part and a second part according to the depth; wherein the first part has a vertical profile, and the second part has an inverted cone profile; the first etching gas contains carbon fluorine gas, carbon hydrogen fluorine gas, oxygen and dilution gas; the side wall of the inverted cone profile has a first angle with the axis of the deep hole structure; The second etching step: introducing a second etching gas to etch the deep hole structure to the barrier layer at the bottom of the deep hole structure, and making the contour side wall of the second part and the axis of the deep hole structure have a second angle, and the second angle is smaller than the first angle; the second etching gas contains CH 4 , carbon fluorine gas, carbon hydrofluorine gas, oxygen.

2. The method for forming a SiN deep hole structure according to claim 1, It is characterized in that The general formula of the carbon fluorine gas is C x1 F y1 , 5>x1>0, y1>0.

3. The method for forming a SiN deep hole structure according to claim 2, It is characterized in that The carbon fluorine gas comprises C 4 F 6 , C 4 F 8 , C x F y At least one of , where 0<x≤3, y>0.

4. The method for forming a SiN deep hole structure according to claim 3, It is characterized in that When the carbon fluorine gas is mainly the C 4 F 6 When the carbon fluorine gas is mainly the C 4 F 8 When the carbon fluorine gas is mainly the C x F y When the carbon-fluorine gas has a third proportion in the first etching gas; the first proportion is less than the second proportion which is less than the third proportion.

5. The method for forming a SiN deep hole structure according to claim 4, It is characterized in that When the carbon fluorine gas is mainly the C 4 F 6 When the oxygen gas is mainly the C 4 F 8 When the oxygen gas has a fifth proportion in the first etching gas; when the carbon fluorine gas is mainly the C x F y When the oxygen gas has a sixth proportion in the first etching gas; the fourth proportion is greater than the fifth proportion which is greater than the sixth proportion.

6. The method for forming a SiN deep hole structure according to claim 1, It is characterized in that The general formula of the carbon, hydrogen and fluorine gas is C x2 H y2 F z2 , 5>x2>0, y2>0, Z2>0.

7. The method for forming a SiN deep hole structure according to claim 6, It is characterized in that The hydrocarbon-hydrofluorine gas comprises CH 2 F 2 , CHF 3 , CH 3 At least one of F.

8. The method for forming a SiN deep hole structure according to claim 7, It is characterized in that When the hydrocarbon-fluorine gas is mainly CHF 3 When the carbon-hydrogen-fluorine gas is mainly CH 2 F 2 When the carbon-hydrogen-fluorine gas has an eighth proportion in the first etching gas; when the carbon-hydrogen-fluorine gas is mainly CH 3 F, the carbon-hydrogen-fluorine gas has a ninth proportion in the first etching gas; the seventh proportion is greater than the eighth proportion, which is greater than the ninth proportion.

9. The method for forming a SiN deep hole structure according to claim 1, It is characterized in that The diluent gas comprises N 2 , at least one of inert gas and CO.

10. The method for forming a SiN deep hole structure according to claim 1, It is characterized in that In the first etching gas, the ratio of carbon fluorine gas: carbon hydrogen fluorine gas: oxygen: dilution gas is 1: (1.5-2.5): (1.5～2.3):(3.5～10)。 11. The method for forming a SiN deep hole structure according to claim 10, It is characterized in that In the first etching step, the flow rate of oxygen is dynamically reduced to enhance the sidewall protection of the deep hole structure.

12. The method for forming a SiN deep hole structure according to claim 11, It is characterized in that In the first etching step, the flow rate of oxygen is dynamically increased to maintain the critical dimension of the first portion.

13. The method for forming a SiN deep hole structure according to claim 1, It is characterized in that In the first etching step, source RF power and / or bias RF power are applied, wherein the source RF power is 200W-900W and the bias RF power is 100W-1200W.

14. The method for forming a SiN deep hole structure according to claim 10, It is characterized in that The proportion of the carbon, hydrogen and fluorine gas in the second etching gas is greater than the proportion of the carbon, hydrogen and fluorine gas in the first etching gas.

15. The method for forming a SiN deep hole structure according to claim 14, It is characterized in that In the second etching step, the flow rate of oxygen is dynamically reduced to enhance the sidewall protection of the first portion.

16. The method for forming a SiN deep hole structure according to claim 15, It is characterized in that In the second etching step, the flow rate of oxygen is dynamically increased to improve the etching rate of the second portion.

17. The method for forming a SiN deep hole structure according to claim 1, It is characterized in that In the second etching step, source RF power and / or bias RF power are applied, wherein the source RF power is 200W-900W and the bias RF power is 100W-1200W.

18. The method for forming a SiN deep hole structure according to claim 1, It is characterized in that In the deep hole structure, the depth of the first part accounts for 50% to 90% of the total depth of the deep hole structure.

19. The method for forming a SiN deep hole structure according to claim 1, It is characterized in that The depth-to-width ratio of the deep hole structure is greater than 5:

1.

20. The method for forming a SiN deep hole structure according to any one of claims 1 to 19, It is characterized in that The first etching step includes a first sub-step and a second sub-step, and the ratio of the carbon fluorine gas to the carbon hydrofluorine gas in the second sub-step is greater than the ratio of the carbon fluorine gas to the carbon hydrofluorine gas in the first sub-step.

21. The method for forming a SiN deep hole structure according to any one of claims 1 to 19, It is characterized in that The second etching step includes a third sub-step and a fourth sub-step, and the ratio of the carbon fluorine gas to the carbon hydrofluorine gas in the fourth sub-step is greater than the ratio of the carbon fluorine gas to the carbon hydrofluorine gas in the third sub-step.

22. The method for forming a SiN deep hole structure according to claim 1, It is characterized in that The process time of the first etching step is longer than the process time of the second etching step.

23. A readable storage medium, It is characterized in that The readable storage medium stores a program or instruction, and when the program or instruction is executed by a processor, the method for forming a SiN deep hole structure according to any one of claims 1 to 22 is implemented.

24. A semiconductor processing device, It is characterized in that include: A processor, a memory, and a program or instruction stored in the memory and executable on the processor, wherein the program or instruction, when executed by the processor, implements the method for forming a SiN deep hole structure as claimed in any one of claims 1 to 22.

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