A feature filling method, buried word line structure and feature filling system

Abstract

The present invention discloses a feature filling method, a buried word line structure and a feature filling system. The feature filling method comprises the following steps: obtaining a substrate including a plurality of spaced features, wherein each feature includes a seed layer with deposition selectivity, and the seed layer is located at the bottom of the feature; using a first precursor to selectively deposit from bottom to top on the seed layer in the feature to form a first filling layer above the seed layer; and in response to the deposition depth of the first filling layer reaching a preset depth, changing the process conditions, and using a second precursor to conformally deposit on the first filling layer to form a second filling layer above the first filling layer. By determining the optimal switching point of the deposition process, the present invention can accurately control the filling time of the two deposition processes, improve the filling rate of the groove, and avoid the risk of uncontrollable bending of the sidewall line after the groove deposition, which is conducive to further improving the performance of the word line structure and increasing the production capacity demand.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a feature filling method, a buried word line structure, and a feature filling system. Background Art

[0002] As the critical dimensions of microelectronic devices continue to decrease, the design and manufacture of these devices on substrates become more and more complex, so the control of critical dimensions and process uniformity becomes more and more important. Semiconductor manufacturing processes used to manufacture microelectronic devices, such as transistors, memory elements, and integrated circuits, may include deposition processes, etching processes, thermal annealing processes, photolithography processes, and doping processes, etc. A commonly used specific semiconductor manufacturing process is to deposit, for example, a metal film into a gap feature, thereby filling the gap feature (for example, a gap, a groove, a through hole, etc.), which is generally referred to as "gap fill". In the manufacture of semiconductor devices, a substrate is used that includes multiple gap features / patterns. The gap feature may include a protruding portion set on the surface of the substrate or a groove portion formed in the surface of the substrate. As the geometric dimensions of semiconductor device structures decrease and high aspect ratio features become more and more common in semiconductor device structures such as DRAM, flash memory, and logic, it becomes increasingly difficult to fill a large number of gap features with metals having the desired properties.

[0003] In the manufacturing process of dynamic random access memory (DRAM), word lines are formed in a polysilicon gate layer at the surface of the substrate. In the buried word line (BWL) process, metal can be used as a gate electrode to bury the word line under the surface of the semiconductor substrate. The traditional metal conformal deposition method will lead to the risk of sidewall line bending (LB) in the trench features. However, the bottom-up deposition method will have the problem of uneven filling speed of each trench gate structure (trench), and if the bottom-up deposition method is used to completely fill the entire trench feature, the filling rate is slow and cannot meet the production capacity requirements.

[0004] In the prior art, the metal deposition rate in the feature can be increased by increasing the substrate temperature, but this method automatically transitions from selective deposition to more conformal deposition during the deposition process, so it is impossible to accurately control the curvature of the feature inner sidewall line, deposition time, deposition thickness, etc. during the deposition process, and there is a risk of sidewall line bending after deposition, so the controllability of this filling method is poor. In addition, in the prior art, the deposition rate can also be increased by increasing the flux of a single precursor, but due to the inherent properties of a specific precursor, even if the flux is increased, the effect of increasing the deposition rate is limited, and this method of gradually increasing the precursor flux during the deposition process also belongs to the automatic transition between conformal and non-conformal filling, so the controllability of this filling method is also relatively poor.

[0005] In order to solve the above-mentioned problems existing in the prior art, the art urgently needs an improved feature filling technology that can comprehensively improve the controllability of the filling process, avoid the risk of uncontrollable side wall line bending after feature filling, and can also accurately control the filling time, improve the feature filling rate, and at the same time ensure that the filling rate of each spaced feature on the substrate is consistent. Summary of the invention

[0006] A brief summary of one or more aspects is given below to provide a basic understanding of these aspects. This summary is not an exhaustive overview of all conceived aspects, and is neither intended to identify the key or decisive elements of all aspects nor to define the scope of any or all aspects. Its only purpose is to give some concepts of one or more aspects in a simplified form as a prelude to a more detailed description that will be given later.

[0007] In order to overcome the above-mentioned defects of the prior art, the present invention provides a feature filling method, a buried word line structure, and a feature filling system, which can comprehensively improve the controllability of the filling process, avoid the risk of uncontrollable side wall line bending after feature filling, and can also accurately control the filling time, improve the feature filling rate, and at the same time ensure that the filling rate of each spaced feature on the substrate is consistent.

[0008] Specifically, the feature filling method provided according to the first aspect of the present invention is used to fill a plurality of spaced features, wherein the features include a bottom and sidewalls and have a certain depth, and the feature filling method includes the following steps: obtaining a substrate including a plurality of spaced features, wherein each of the features includes a seed layer with deposition selectivity, and the seed layer is located at the bottom of the feature; using a first precursor to perform bottom-up selective deposition on the seed layer in the feature to form a first filling layer above the seed layer; and in response to the deposition depth of the first filling layer reaching a preset depth, changing the process conditions, and using a second precursor to perform conformal deposition on the first filling layer to form a second filling layer above the first filling layer.

[0009] Further, in some embodiments of the present invention, in response to the deposition depth of the first filling layer reaching a preset depth, the step of changing the process conditions and using a second precursor to perform conformal deposition on the first filling layer to form a second filling layer above the first filling layer includes: judging whether the deposition depth of the first filling layer reaches the preset depth, wherein the preset depth is determined based on a threshold value of the degree of curvature of the sidewall line of the feature; in response to the deposition depth of the first filling layer not reaching the preset depth, continuing to deposit the first filling layer; and in response to the deposition depth of the first filling layer reaching the preset depth, changing the process conditions and using the second precursor to perform conformal deposition on the first filling layer to form the second filling layer above the first filling layer.

[0010] Further, in some embodiments of the present invention, the preset depth of the feature is calibrated according to the curvature of the sidewall line of the feature after the deposition process is completed, wherein the step of calibrating the preset depth of the feature includes: preparing a plurality of calibration features, wherein the calibration features have a bottom and a sidewall, and the bottom has a seed layer; selectively depositing the first precursor inside each of the calibration features, and performing conformal deposition based on the second precursor on the formed first filling layer to form a second filling layer above the first filling layer; and determining the curvature of the sidewall line of each of the calibration features according to a sidewall line curvature formula, wherein the sidewall line curvature formula is as follows:

[0011]

[0012] LB represents the curvature of the sidewall line, a i represents the distance between the center lines of the upper ends of the sidewalls between the i-th calibration feature and the i+1-th calibration feature before the deposition process is performed, c irepresents the distance between the center lines of the upper ends of the side walls between the ith calibration feature and the (i+1)th calibration feature after the deposition process is completed, and n represents the number of the calibration features; according to a preset bending degree threshold, determining at least one calibration feature of qualified quality; and determining the preset depth according to the bending degree of the side wall line of the at least one calibration feature of qualified quality.

[0013] Further, in some embodiments of the present invention, the step of determining the preset depth based on the curvature of the sidewall line of the at least one qualified calibration feature includes: taking the bottom of the qualified calibration feature as the starting position, and the sum of the depths of the seed layer and the first filling layer as the first preset depth; or taking the upper surface of the seed layer within the qualified calibration feature as the starting position, and the depth of the first filling layer as the second preset depth.

[0014] Furthermore, in some embodiments of the present invention, taking the bottom of the qualified calibration feature as the starting position, the first preset depth corresponding to the bending degree threshold ranges from 30% to 40% of the total depth of the qualified calibration feature.

[0015] Furthermore, in some embodiments of the present invention, taking the upper surface of the seed layer within the qualified calibration feature as the starting position, the second preset depth corresponding to the bending degree threshold ranges from 20% to 30% of the total depth of the qualified calibration feature.

[0016] Furthermore, in some embodiments of the present invention, the first precursor and the second precursor are precursors of the same metal.

[0017] Furthermore, in some embodiments of the present invention, the first precursor and the second precursor are both molybdenum-containing precursors, wherein the molybdenum-containing precursor is molybdenum chloride or molybdenum oxychloride, wherein the number of atoms of chlorine element in the first molybdenum precursor is greater than the number of atoms of chlorine element in the second molybdenum precursor.

[0018] Furthermore, in some embodiments of the present invention, the seed layer is made of metal nitride, and the metal nitride includes any one or more combinations of titanium nitride, tungsten nitride, tungsten carbonitride, and tantalum nitride.

[0019] Furthermore, in some embodiments of the present invention, in the process conditions, the process temperature range of the deposition of the first molybdenum precursor is 400°C to 500°C, and the process temperature range of the deposition of the second precursor is 500°C to 600°C.

[0020] Furthermore, in some embodiments of the present invention, the feature filling method further includes: in response to the second filling layer completing the filling of each of the features, continuing to introduce the second precursor until the second filling layer covers the openings of each of the features.

[0021] In addition, according to the second aspect of the present invention, there is also provided a buried word line structure, comprising: a substrate, comprising a plurality of spaced features, wherein each of the features comprises a seed layer having deposition selectivity, and the seed layer is located at the bottom of the feature; a first filling layer, disposed above the seed layer, and the first filling layer is obtained by selectively depositing a first precursor on the seed layer in the feature from bottom to top; and a second filling layer, disposed above the first filling layer, and the second filling layer is obtained by conformally depositing a second precursor on the first filling layer after the deposition depth of the first filling layer reaches a preset depth.

[0022] In addition, the above-mentioned feature filling system provided according to the third aspect of the present invention includes: a reaction chamber, in which a substrate including multiple spaced features to be feature filled is placed, wherein each of the features includes a seed layer with deposition selectivity, and the seed layer is located at the bottom of the feature; a first precursor source, connected to the reaction chamber to provide a first precursor into the reaction chamber; a second precursor source, connected to the reaction chamber to provide a second precursor into the reaction chamber; and a controller, connected to the first precursor source and the second precursor source, configured to: turn on the first precursor source, and introduce the first precursor into the reaction chamber so that the first precursor is selectively deposited from bottom to top on the seed layer in the feature to form a first filling layer above the seed layer, and in response to the deposition depth of the first filling layer reaching a preset depth, change the process conditions in the reaction chamber, turn off the first precursor source, and turn on the second precursor source so that the second precursor is conformally deposited on the first filling layer to form a second filling layer above the first filling layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above features and advantages of the present invention can be better understood after reading the detailed description of the embodiments of the present disclosure in conjunction with the following drawings. In the drawings, the components are not necessarily drawn to scale, and components with similar related properties or features may have the same or similar reference numerals.

[0024] Figure 1 A schematic structural diagram of a buried word line structure provided according to some embodiments of the present invention is shown;

[0025] Figure 2A flow chart of a feature filling method provided according to some embodiments of the present invention is shown;

[0026] Figure 3 A schematic diagram of a switching process between a first molybdenum precursor and a second molybdenum precursor provided according to some embodiments of the present invention is shown;

[0027] Figure 4 A schematic diagram of a model of a buried word line structure before filling provided according to some embodiments of the present invention is shown;

[0028] Figure 5 A schematic diagram showing a model of a buried word line structure after filling according to some embodiments of the present invention; and

[0029] Figure 6 A simplified structural diagram of a feature filling system provided according to some embodiments of the present invention is shown.

[0030] Reference numerals:

[0031] 10 buried word line structure;

[0032] 100 substrate;

[0033] 101 features;

[0034] 110 seed layer;

[0035] 120 first filling layer;

[0036] 130 second filling layer;

[0037] Steps S210 to S230;

[0038] Steps S231 to S233;

[0039] 400 calibration substrate;

[0040] 401~40n calibration features;

[0041] 411-41n side wall;

[0042] 401a left wall;

[0043] 401b right side wall;

[0044] h1 first preset depth;

[0045] h2 second preset depth;

[0046] 600 Feature Filling System;

[0047] 610 reaction chamber;

[0048] 611 Pallet;

[0049] 621 first precursor source;

[0050] 622 second precursor source;

[0051] 623 Reducing gas source;

[0052] 630 Inert gas source;

[0053] 640 Vacuum pump;

[0054] 650 Pneumatic valve;

[0055] 660 pressure gauge; and

[0056] 670 Mass Flow Controller. DETAILED DESCRIPTION

[0057] The following specific embodiments illustrate the implementation of the present invention, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiment, this does not mean that the features of this invention are limited to this implementation. On the contrary, the purpose of introducing the invention in conjunction with the implementation is to cover other options or modifications that may be extended based on the claims of the present invention. In order to provide a deep understanding of the present invention, the following description will include many specific details. The present invention can also be implemented without using these details. In addition, in order to avoid confusion or blurring the focus of the present invention, some specific details will be omitted in the description.

[0058] 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 or an electrical 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.

[0059] In addition, the terms "upper", "lower", "left", "right", "top", "bottom", "horizontal" and "vertical" used in the following description should be understood as the directions shown in the paragraph and the related drawings. Such relative terms are only used for the convenience of description and do not mean that the device described therein must be manufactured or operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0060] It is understood that although the terms "first", "second", "third", etc. may be used herein to describe various components, regions, layers and / or parts, these components, regions, layers and / or parts should not be limited by these terms, and these terms are only used to distinguish different components, regions, layers and / or parts. Therefore, the first component, region, layer and / or part discussed below may be referred to as a second component, region, layer and / or part without departing from some embodiments of the present invention.

[0061] As mentioned above, in the prior art, the deposition rate of the metal in the feature can be increased by increasing the substrate temperature, but this method automatically transitions from selective deposition to more conformal deposition during the deposition process, so it is impossible to accurately control the curvature of the feature inner sidewall line, deposition time, deposition depth, etc. during the deposition process, and there is a risk of sidewall line bending after deposition, so the controllability of this filling method is poor. In addition, in the prior art, the deposition rate can also be increased by increasing the flux of a single precursor, but due to the inherent properties of a specific precursor, even if the flux is increased, the effect of increasing the deposition rate is limited, and this method of gradually increasing the precursor flux during the deposition process also belongs to the automatic transition between conformal and non-conformal filling, so the controllability of this filling method is also relatively poor.

[0062] In order to solve the above-mentioned problems existing in the prior art, the present invention provides a feature filling method, a buried word line structure, and a feature filling system, which can comprehensively improve the controllability of the filling process, avoid the risk of uncontrollable side wall line bending after feature filling, and can also accurately control the filling time, improve the feature filling rate, and at the same time ensure that the filling rate of each spaced feature on the substrate is consistent.

[0063] In some non-limiting embodiments, the feature filling method provided in the first aspect of the present invention may be implemented by the feature filling system provided in the third aspect of the present invention to obtain the buried word line structure provided in the second aspect of the present invention.

[0064] The specific process of the above-mentioned feature filling method will be described below in combination with some buried word line structures and embodiments of the feature filling system. Those skilled in the art will understand that the embodiments of these feature filling systems are only some non-restrictive implementation methods provided by the present invention, which are intended to clearly demonstrate the main concept of the present invention and provide some specific solutions that are convenient for the public to implement, and do not constitute restrictions on the implementation subjects of each step in these feature filling methods. Similarly, the feature filling method will not be used to limit all working modes or all functions of the feature filling system. The feature filling method will not limit the entire structure of the generated buried word line structure.

[0065] Specifically, please see Figure 1 , Figure 1 A schematic structural diagram of a buried word line structure provided according to some embodiments of the present invention is shown.

[0066] like Figure 1 As shown, in some embodiments of the present invention, the buried word line structure 10 may include a substrate 100, a first filling layer 120 and a second filling layer 130. The substrate 100 may include a plurality of groove-shaped spaced features 101, wherein the features 101 may include a bottom and a sidewall and have a certain depth. The interior of each feature 101 may include a seed layer 110 having deposition selectivity, and the seed layer 110 is located at the bottom of the feature 101. The first filling layer 120 may be disposed above the seed layer 110, and specifically, the first filling layer 120 may be obtained by selectively depositing a first precursor from bottom to top on the upper surface of the seed layer 110 in the feature 101. The second filling layer 130 may be disposed above the first filling layer 120, and specifically, the second filling layer 130 may be obtained by conformally depositing a second precursor on the first filling layer 120 after the deposition depth of the first filling layer 120 reaches a preset depth.

[0067] Furthermore, the first precursor and the second precursor may preferably be precursors of the same metal to ensure that the metal material filled in the feature 101 is always the same, thereby ensuring that each feature 101 in the substrate 100 can maintain the same etching rate in the subsequent etching process, and that the retained material in the trench gate structure (trench) after etching must be the same metal, that is, multiple metal gate electrodes with the same depth (or thickness) are formed. For example, optionally, in some embodiments of the present invention, the first precursor and the second precursor may both be precursors containing molybdenum.

[0068] The following will take two molybdenum-containing precursors, a first molybdenum precursor and a second molybdenum precursor, as examples to further introduce the buried word line structure 10 protected by the present invention on the one hand, and the feature filling method to be protected on the other hand.

[0069] Please see Figure 2 , Figure 2 A flow chart of a feature filling method provided according to some embodiments of the present invention is shown.

[0070] like Figure 2 As shown, in some embodiments of the present invention, the feature filling method may include the following steps S210: obtaining a substrate including a plurality of spaced features, wherein each feature includes a seed layer having deposition selectivity, and the seed layer is located at the bottom of the feature.

[0071] Specifically, if Figure 1 and Figure 2As shown, in some optional embodiments, the feature 101 in the substrate 100 may be in the shape of a trench including a bottom and one or more sidewalls. The bottom of the feature 101 may include a seeding layer 110 (seeding layer / plug) having deposition selectivity.

[0072] In some embodiments, the bottom surface and sidewall surface of feature 101 may be covered by dielectric materials such as silicon substrate material (e.g., SiO2), oxide material, nitride, etc. to form a dielectric surface. The "deposition selectivity" herein means that the seed layer 110 may be preferably deposited at the bottom of feature 101, rather than on the sidewall of feature 101. This selectivity may be expressed as a ratio of deposition rate or a ratio of deposition thickness after a certain number of deposition cycles.

[0073] Optionally, before filling the feature 101, the metal surface including the seed layer 110 and the dielectric surface of the sidewalls may be subjected to an optional pretreatment. In some optional embodiments, the pretreatment may include any metal oxide for reducing the metal surface, for example, the metal-containing surface of the seed layer 110 in the substrate 100 may be exposed to a reducing agent, which may be a hydrogen-containing reactant. In other embodiments, the pretreatment of the feature surface may also include exposing the feature to a hydrogen-containing plasma or other related halogen-based plasma for treatment.

[0074] Furthermore, the seed layer 110 can be made by conformal deposition. Since conformal deposition has the property of allowing film coating on a three-dimensional topological surface, and the deposited film can retain the original shape of the topological surface (for example, including the surface outside the feature, the bottom and sidewall inside), it is possible to manufacture complex devices beyond the plane limitation, such as FinFET, MEMS / NEMS or storage cells. In addition, the seed layer 110 can be made of metal nitride, for example, titanium nitride (TiN), molybdenum nitride (MoN x ), tungsten nitride (WN), tungsten carbonitride (WC x N y ), and one or more of tantalum nitride (TaN). Optionally, the seed layer 110 may also be made of titanium aluminum carbide (TiAl x C y ), titanium silicide (TiSi2), etc. The seed layer 110 composed of the above materials can show good selectivity to the dielectric material on the bottom surface of the feature 101.

[0075] Further, in some preferred embodiments, after the seed layer 110 is deposited in the initial feature 101, a purification gas (such as NF6) can be used to clean and / or etch the feature 101 after the seed layer 110 is deposited, so as to form a clear feature 101 including the seed layer 110 again. For example, the substrate 100 with the seed layer 110 deposited at the bottom of the feature 101 can be transferred to an etching device for pretreatment such as dry etching such as gas phase etching.

[0076] Continue as Figure 2 As shown, the feature filling method provided by the present invention may further include step S120: using a first precursor to perform bottom-up selective deposition on the seed layer in the feature to form a first filling layer above the seed layer.

[0077] Specifically, it can be combined Figure 1 and Figure 2 As shown together, after completing the above step S210 to deposit the seed layer 110 to the bottom of the feature 101, the process conditions of the reaction environment can be adjusted to make the reaction environment suitable for the deposition process of the first precursor. Optionally, in some embodiments, the deposition process of the first precursor can be an atomic layer deposition (ALD) process. The ALD process specifically includes first pulsing the first precursor; after the first precursor is pulsed, a purge operation can be performed, such as using argon or other inert gases to clear any unadsorbed precursors in the reaction chamber. Repeat the above operation until the deposition process based on the first precursor is completed.

[0078] When performing the deposition process of the first molybdenum precursor, the temperature of the reaction environment can be adjusted to 400° C. to 500° C., and the process pressure can be adjusted to, for example, 1 torr to 50 torr or 1 torr to 100 torr. As mentioned above, when the deposition process of the first molybdenum precursor uses the ALD process, the reducing agent of molybdenum in the process can use hydrogen. The first molybdenum precursor can be selectively deposited from bottom to top on the upper surface of the seed layer 110 in the feature 101 to generate the first filling layer 120.

[0079] In some preferred embodiments, since the first precursor in this embodiment is a first molybdenum precursor, the seed layer 110 can further be made of titanium nitride material to form a titanium nitride seed layer 110 (TiN seeding layer). The titanium nitride seed layer 110 has a better deposition selectivity for the molybdenum-containing precursor relative to other metal nitrides, that is, the first molybdenum precursor is more likely to be deposited on the surface of the titanium nitride seed layer 110. In addition, since the seed layer 110 at the bottom of the feature 101 has a deposition selectivity relative to the sidewall of the feature 101, the first molybdenum precursor can selectively deposit a molybdenum film only on the upper surface of the seed layer 110 at the bottom of the feature 101, and not on the sidewall of the feature 101 and other directions, thereby forming a "bottom up fill", thereby reducing the risk of sidewall line bending during the feature filling process.

[0080] Furthermore, in this embodiment, the titanium nitride seed layer 110 itself can also be bonded to the silicon oxide (SiO x ) form a good bonding, thus avoiding the pullup problem during the post annealing process.

[0081] Optionally, the deposition of the first molybdenum precursor can specifically use an ALD process, by performing multiple cycles of the ALD process, so that the first molybdenum precursor is selectively filled from bottom to top on the upper surface of the seed layer 110 at the bottom of the feature 101 relative to the side wall surface of the feature 101 of silicon or oxide or nitride, to form a first filling layer 120.

[0082] In the above step S220, by performing bottom-up selective deposition of a molybdenum film based on a first molybdenum precursor in the feature 101 including the pretreated seed layer 110, high-quality void-free filling can be achieved at the bottom of the feature 101, and the bottom-up selective filling deposition process will not affect the curvature of the side wall of the feature 101.

[0083] Continue as Figure 2 As shown, the above-mentioned feature filling method provided by the present invention may also include step S230: in response to the deposition depth of the first filling layer reaching a preset depth, changing the process conditions, and using a second precursor to perform conformal deposition on the first filling layer to form a second filling layer above the first filling layer.

[0084] In some embodiments, the deposition process of the second precursor may also be an ALD process, and the deposition process based on the second precursor is the same as the deposition process based on the first precursor, which will not be repeated here.

[0085] Furthermore, if Figure 3 As shown, step S230 can be embodied as steps S231 to S233. In some optional embodiments, step S231 can be performed first: determining whether the deposition depth of the first filling layer reaches a preset depth.

[0086] Please combine Figure 2 It is commonly understood that in some embodiments, during the bottom-up selective deposition using a first molybdenum precursor on the seed layer 110 at the bottom of the feature 101 to fill the feature 101, the deposition depth of the first filling layer 120 can be directly or indirectly detected by a measuring instrument, wherein the preset depth can be determined based on a threshold value of the curvature of the sidewall line of the feature 101.

[0087] Afterwards, step S232 or step S233 may be performed. Step S232 includes: in response to the deposition depth of the first filling layer 120 not reaching the preset depth, continuing to deposit the first filling layer 120. Step S233 includes: in response to the deposition depth of the first filling layer 120 reaching the preset depth, stopping the introduction of the first molybdenum precursor, and changing the process conditions of the reaction environment, for example, adjusting the reaction temperature to 500°C to 600°C to be suitable for the deposition process of the second molybdenum precursor. The second molybdenum precursor is introduced so that the second molybdenum precursor is conformally deposited on the first filling layer 120, thereby forming a second filling layer 130 above the first filling layer 120.

[0088] Further, the molybdenum-containing precursor may be molybdenum chloride or molybdenum oxychloride, and since the greater the atomic number of the chlorine element in the molybdenum-containing precursor, the slower the deposition rate of the molybdenum-containing precursor, therefore, in some embodiments of the present invention, the atomic number of the chlorine element in the first molybdenum precursor (Cl x1 ) can be greater than the number of atoms of chlorine in the second molybdenum precursor (Cl x2 ), that is, x1<x2. In the above embodiment of the present invention, the bottom-up selective deposition in step S220 can select a molybdenum-containing precursor with a larger number of chlorine atoms and a slower deposition rate, so as to ensure as much as possible that the sidewall line curvature is smaller in feature 201 and the morphology of feature 101 is not deformed, thereby ensuring the subsequent film quality. In the next step, the conformal deposition in step S230 can select a molybdenum-containing precursor with a smaller number of chlorine atoms and a faster deposition rate, so as to speed up the deposition process and improve the filling efficiency of the feature.

[0089] Optionally, the first molybdenum precursor may be molybdenum pentachloride (MoCl5), and the second molybdenum precursor may include molybdenum dichloride (MoO2Cl2) having a deposition rate greater than that of molybdenum pentachloride, thereby achieving an increase in the filling rate of feature 101 and rapid film formation. In addition, molybdenum pentachloride has better selectivity for metals than molybdenum dichloride. In addition, when the molybdenum is deposited from bottom to top on the upper surface of the titanium nitride seed layer 110 through the first molybdenum precursor, the adhesion between molybdenum and titanium nitride is also very strong, and it is not easy to be disconnected during the annealing process.

[0090] Next, see Figure 4 and Figure 5 , Figure 4 shows a schematic diagram of a model of a buried word line structure before filling provided according to some embodiments of the present invention, Figure 5 A schematic diagram of a model of a filled buried word line structure provided according to some embodiments of the present invention is shown.

[0091] In some embodiments of the present invention, the preset depth of the feature 101 can be calibrated according to the curvature of the sidewall line of the feature 101 after the deposition process is completed. The step of calibrating the preset depth can further include the following process: First, a plurality of calibration features can be prepared, the calibration features having a bottom and a sidewall, and the bottom having a seed layer.

[0092] like Figure 4 As shown, before the deposition filling process is performed, the calibration substrate 400 may evenly include a plurality of calibration features 401, 402, 403, 404 ... 40n. The widths of these calibration features 401, 402, 403, 404 ... 40n themselves, and the thicknesses of the base columnar sidewalls 411, 412, 413 ... 41n between the intervals of the calibration features 401, 402, 403, 404 ... 40n may all be set to constant values. In other words, as Figure 4 As shown, the upper opening widths a1…a between adjacent marking features 401, 402, 403, 404…40n are n Can all be set to constant values.

[0093] Afterwards, each of the calibration features 401, 402, 403, 404, ... 40n (including the titanium nitride seed layer 110, Figure 5 Selective deposition of a first molybdenum precursor at different characteristic depths is performed in the inner portion (not shown), and then conformal deposition based on a second molybdenum precursor is performed on each of the formed first filling layers 120 to form each second filling layer 130 above each of the first filling layers 120.

[0094] After the deposition process of the first molybdenum precursor is switched to the deposition process of the second molybdenum precursor, the feature filling method is also switched from bottom up fill deposition to conformal deposition. In the bottom up fill deposition process, since the molybdenum film of the first filling layer is selectively deposited on the bottom of the calibration features 401, 402, 403, 404...40n, the side walls of the calibration features 401, 402, 403, 404...40n will not be affected. However, in the subsequent conversion to the conformal deposition process, the molybdenum film of the second filling layer will be deposited on the side walls of the calibration features 401, 402, 403, 404...40n. The molybdenum film deposited on the side walls will cause a backlog on the side walls, which may easily cause line bending of the side walls, which may cause problems such as groove non-uniformity and contact landing in the downstream process, thereby resulting in DRAM yield loss.

[0095] like Figure 5 As shown, after the deposition filling process is completed, due to the backlog of the molybdenum film deposited on the side walls 411, 412, 413...41n, the base columnar side walls 411, 412, 413...41n between the spaced calibration features 401, 402, 403, 404...40n will be deformed and bent. For example, the left side wall 401a and the right side wall 401b of the calibration feature 401 will produce a linear bending deformation after deposition, and the feature will become a V-shaped groove, thereby resulting in the upper end opening width a1...a between each adjacent calibration feature 401, 402, 403, 404...40n. n Therefore, the transition condition between the deposition process of the first molybdenum precursor and the deposition process of the second molybdenum precursor is to ensure that the filling rate of the entire calibration features 401, 402, 403, 404...40n is the fastest, and at the same time, it is also necessary to ensure that the sidewall line bending (line bending) does not occur as much as possible during the conformal deposition process of the second molybdenum precursor. To this end, the sidewall line bending can be observed at any time during the deposition process of the second molybdenum precursor through an observation device, such as an electron microscope slice.

[0096] Those skilled in the art can understand that Figure 5 The bending of the side wall lines in the figure is only for illustration, and the deformation ratio of the side walls 411, 412, 413 ... 41n is exaggerated. The actual bending deformation of the line is very small, and Figure 5 The shapes of the marked features 401 , 402 , 403 , 404 . . . 40n are also only examples, and they may actually be closer to a V-shaped groove or a trapezoidal groove.

[0097] like Figure 4 and Figure 5As shown, the line curvature degree of the sidewalls 411, 412, 413 ... 41n in each calibration feature 401, 402, 403, 404 ... 40n before and after the deposition process can be determined according to the sidewall line curvature formula, wherein the sidewall line curvature formula can be as follows:

[0098]

[0099] LB represents the curvature of the sidewall line, a i represents the distance between the center lines of the upper ends of the sidewalls between the i-th calibration feature and the i+1-th calibration feature before the deposition process (i.e., the distance between the openings at the upper ends of the calibration features 401, 402, 403, 404, ... 40n), c i It represents the distance between the center lines of the upper ends of the side walls between the ith calibration feature and the (i+1)th calibration feature after the deposition process is completed (i.e., the distance between the openings at the upper ends of calibration features 401, 402, 403, 404...40n), where n represents the number of calibration features.

[0100] According to the preset bending degree threshold, at least one qualified calibration feature can be determined. Then, the preset depth can be determined according to the sidewall bending degree LB of the at least one qualified calibration feature. In some preferred embodiments, the preset bending degree threshold can be 1nm, that is, LB = (|c1-a1| + |c2-a2| + |c3-a3| + ... + |c n -a n |) / n≤1nm.

[0101] Preferably, in the process of determining the calibration preset depth, a plurality of calibration features 401, 402, 403, 404...40n in a batch of calibration substrates 400 are usually used for testing, and the average value of the side wall line curvature LB of each calibration feature 401, 402, 403, 404...40n in each calibration substrate 400 is taken as the preset depth to ensure the accuracy of the preset depth, which is facilitating the precise control of the filling time.

[0102] Further, in some optional embodiments of the present invention, the step of determining the preset depth according to the curvature of the sidewall line of at least one qualified calibration feature may include two cases.

[0103] like Figure 1As shown, when the bottom of the qualified calibration feature is taken as the starting position, the sum of the depths of the seed layer 110 and the first filling layer 120 can be used as the first preset depth h1. At this time, the range of the first preset depth h1 corresponding to the bending degree threshold of 1nm can be 30% to 40% of the total depth of the qualified calibration feature. When the upper surface of the seed layer 110 in the qualified calibration feature is taken as the starting position, the depth of the first filling layer 120 can be used as the second preset depth h2. At this time, the range of the second preset depth h2 corresponding to the bending degree threshold of 1nm can be 20% to 30% of the total depth of the qualified calibration feature.

[0104] That is, in this embodiment, when the first filling layer 120 deposited by the first molybdenum precursor (MoCl5) at a slower first deposition rate is deposited in the feature 101 to the first preset depth h1 or the second preset depth h2, the process conditions can be changed, and the second molybdenum precursor (MoO2Cl2) can be introduced, and the second molybdenum precursor can continue to fill the feature 101 at a faster second deposition rate. At this time, it can not only ensure that after the conformal deposition of the second molybdenum precursor is completed, the curvature of the sidewall in the feature 101 is small enough (LB≤1nm), but also ensure that the overall filling time of the feature 101 is the shortest and the filling rate is the fastest.

[0105] In contrast, if the first molybdenum precursor is switched to the second molybdenum precursor in advance before the first filling layer reaches the first preset depth h1 or the second preset depth h2, although the second molybdenum precursor with a higher deposition rate is used in advance for feature filling, the filling rate can be accelerated, but the conformal deposition of the second molybdenum precursor will cause obvious line bending on the feature sidewall, affecting the problems of groove non-uniformity and contact landing in the downstream process, thereby causing DRAM yield loss. On the contrary, if the first molybdenum precursor is switched to the second molybdenum precursor after the first filling layer has reached the first preset depth h1 or the second preset depth h2, it is easy to cause the filling rate of the entire feature to be too slow, thereby affecting production capacity.

[0106] Therefore, in the present invention, by calibrating a precise preset depth as the switching condition for the deposition process of the first molybdenum precursor and the deposition process of the second molybdenum precursor, it is possible to determine the optimal switching time of the deposition process, and accurately control the filling time to improve the filling rate of the groove, while also avoiding the risk of uncontrollable bending of the side wall line after wafer groove deposition.

[0107] In the above step S230, by adopting two different deposition processes, the filling process of the feature 101 is deposited in two steps, and the respective process conditions and process switching time are controlled respectively, so that the molybdenum deposition in each step can be controlled, for example, the deposition time and deposition depth of the deposition process based on the first molybdenum precursor and the second molybdenum precursor can be accurately controlled respectively. In addition, the selective deposition with a slower rate in the first step is conducive to ensuring that the feature sidewall in the substrate has no wireless bending (or very small line bending), and then the conformal deposition with a faster rate in the second step can improve the deposition rate. The combination of the two can further control the precise sidewall line bending degree (LB≤1nm), ensure the deposition quality (good line bending), and also ensure the consistency of the filling rate of each feature on the substrate. The main benefits of the present invention also include ensuring that the subsequent etching rate is consistent, ensuring the performance of the deposited film, thereby improving the yield of the buried word line structure 10, and then improving the yield. In addition, since micropores are less formed in the deposition filling process itself, there will be no disconnection caused by the formation of micropores due to annealing, thus avoiding the disconnection problem of post-annealing.

[0108] Combine again Figure 1 and Figure 2 In some optional embodiments, after executing the above steps S210 to S230, the feature filling method may further include: in response to the first filling layer 120 completing the filling of the feature 101, the second molybdenum precursor may continue to be introduced until the second filling layer 130 covers the opening of the feature 101.

[0109] Generally speaking, after the feature filling process on the substrate 100 is completed, a subsequent etching process is required, including etching the metal material (molybdenum material) in the feature 101 to a certain depth. For example, the molybdenum material in the feature can be etched to a depth of nearly 20%. By continuing to deposit the second filling layer 130 until the opening of the feature 101 is overburdened, it can be ensured that the metal material filled in the feature 101 is always the same, that is, metal molybdenum, so as to ensure that each feature 101 in the substrate 100 can maintain the same etching rate in the subsequent etching process, and the retained material in the trench gate structure (trench) after etching must be molybdenum, that is, a molybdenum metal gate electrode with the same depth (or thickness) is formed. Afterwards, in the BWL process, the molybdenum metal gate electrode can be used to bury the word line under the surface of the semiconductor substrate to complete the manufacture of the DRAM unit.

[0110] In the actual production process, due to the different shapes of the features in the substrate and the process environment (for example, close to or far from the edge of the reaction chamber, etc.), the filling depth of the molybdenum film filled by bottom-up selective deposition in each feature may be different. Therefore, if a second metal different from molybdenum is used for covering, when each feature is subsequently etched to the same depth, some features may have residual second metal, which will cause the molybdenum word line embedding process of these features to be unqualified, reducing the yield. In addition, if two metals are used for feature filling, the different etching rates of each feature will also cause the second metal to remain in the feature after etching. The present invention can avoid the above problems by using the same metal for the comprehensive deposition method of the above two different deposition processes.

[0111] Although the above methods are illustrated and described as a series of actions for simplicity of explanation, it should be understood and appreciated that these methods are not limited by the order of the actions, because according to one or more embodiments, some actions may occur in a different order and / or concurrently with other actions from those illustrated and described herein or not illustrated and described herein but understandable to those skilled in the art.

[0112] So far, the feature filling method and buried word line structure protected by the first and second aspects of the present invention have been introduced. Figure 6 , Figure 6 A simplified structural diagram of a feature filling system provided according to some embodiments of the present invention is shown.

[0113] like Figure 6 As shown, in some embodiments of the present invention, the feature filling system 600 may include a reaction chamber 610, which may include a tray 611 inside to support a substrate 100 including a plurality of spaced features to be filled with features, and the interior of each feature may include a seed layer with deposition selectivity, and the seed layer is located at the bottom of the feature.

[0114] Optionally, the tray 611 may be equipped with some functional devices to perform corresponding functional support on the substrate 100 supported thereon, such as vacuum adsorption, electrostatic adsorption and corresponding desorption, etc. Further optionally, for example, the tray 611 may include a heater to heat the substrate 100 during the support process.

[0115] Continue as Figure 6 As shown, the reaction chamber 610 can be connected to a first precursor source 621 and a second precursor source 622. The first precursor source 621 can provide a first precursor into the reaction chamber 610 to perform a deposition process of the first precursor. The second precursor source 622 can provide a second precursor into the reaction chamber 610 to perform a deposition process based on the second precursor.

[0116] Furthermore, when the first precursor is a molybdenum-containing precursor and the ALD process is used for deposition, the reaction chamber 610 may also be connected to a reducing gas source 623. The reducing gas source 623 may include a reducing gas such as hydrogen as a reducing agent to provide a reducing gas (such as hydrogen) into the reaction chamber 610. Specifically, during the ALD process, the first molybdenum precursor and the reducing gas may be pulsed alternately, and the first molybdenum precursor may be rapidly reduced by multiple pulses of the reducing gas, thereby depositing a high-purity, low-resistivity metal molybdenum film.

[0117] Furthermore, the feature filling system 600 may also include an inert gas source 630 connected to the reaction chamber 610 to provide inert gas into the reaction chamber 610. Specifically, each time after the precursor or reducing agent is introduced into the reaction chamber 610, the inert gas may be introduced into the reaction chamber 610 to purge the various equipment components in the system.

[0118] Optionally, a plurality of pneumatic valves 650 may be provided on the respective connecting pipelines between the first precursor source 621, the second precursor source 622, the reducing gas source 623, and the inert gas source 630 and the reaction chamber 610, respectively, to control the on-off conditions of the first precursor, the second precursor, the reducing gas, and the inert gas. Preferably, each connecting pipeline may further include a pressure gauge 660 and a mass flow controller 670, respectively, to detect the pipeline pressure and adjust the flow rate of the first precursor, the second precursor, the reducing gas, and the inert gas.

[0119] The feature filling system 600 may also include a controller, connecting the first precursor source 621 and the second precursor source 622. The controller may be configured to open the pneumatic valve 650 on the connecting pipeline corresponding to the first precursor source 621, and introduce the first precursor into the reaction chamber 610, so that the first precursor is selectively deposited from bottom to top on the seed layer in the feature to form a first filling layer above the seed layer. In response to the deposition depth of the first filling layer reaching a preset depth, the controller may change the process conditions in the reaction chamber 610, turn off the pneumatic valve 650 on the connecting pipeline corresponding to the first precursor source 621, and open the pneumatic valve 650 on the connecting pipeline corresponding to the second precursor source 622, so that the second precursor is conformally deposited on the first filling layer to form a second filling layer above the first filling layer.

[0120] Alternatively, if Figure 6As shown, the reaction chamber 610 in the feature filling system 600 can also be connected to an exhaust pump 640, which is used to extract the residual reaction gas in the reaction chamber 610 after the deposition process is completed. Optionally, the reaction chamber 610 can also include a plurality of pneumatic valves on the connection pipeline corresponding to the exhaust pump 640, which are used to control the on-off status of the residual gas extraction in the chamber, and a pressure gauge 660, which is used to detect the pipeline pressure.

[0121] In summary, the present invention provides a feature filling method, a buried word line structure, and a feature filling system. By calibrating a precise preset depth as a switching condition for a deposition process of a first precursor and a deposition process of a second precursor, the optimal switching time of the deposition process can be determined, and the filling method and filling time of the two deposition processes can be accurately controlled, thereby improving the filling rate of the groove and ensuring that the filling rate of each spacing feature on the substrate is consistent. At the same time, the risk of uncontrollable bending of the side wall line after wafer groove deposition can be avoided, thereby comprehensively improving the controllability of the filling process, which is conducive to further improving the performance of the word line structure and increasing production capacity requirements.

[0122] The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to those skilled in the art, and the general principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein, but should be granted the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A feature filling method for filling a plurality of spaced features, wherein the features include a bottom and a sidewall and have a certain depth, wherein: The feature filling method comprises the following steps: Obtaining a substrate including a plurality of spaced features, wherein each of the features includes a seed layer having a deposition selectivity therein, and the seed layer is located at a bottom of the feature; selectively depositing a first precursor from bottom to top on the seed layer within the feature to form a first fill layer above the seed layer; and Determining whether the deposition depth of the first filling layer reaches a preset depth, wherein the preset depth is determined based on a threshold value of the curvature of the sidewall line of the feature, and the step of calibrating the preset depth of the feature includes: preparing a plurality of calibration features, the calibration features having a bottom and a sidewall, and the bottom having a seed layer; Performing selective deposition of the first precursor inside each of the marked features, and performing conformal deposition based on a second precursor on the formed first filling layer to form a second filling layer above the first filling layer; According to the sidewall line bending formula, the sidewall line bending degree of each calibration feature is determined respectively, wherein the sidewall line bending formula is as follows: LB represents the curvature of the sidewall line, a i represents the distance between the center lines of the upper ends of the sidewalls between the i-th calibration feature and the i+1-th calibration feature before the deposition process is performed, c i represents the distance between the center lines of the upper ends of the side walls between the ith calibration feature and the (i+1)th calibration feature after the deposition process is completed, and n represents the number of the calibration features; Determining at least one calibration feature of acceptable quality according to a preset bending degree threshold; and Determining the preset depth according to the curvature of the sidewall line of the at least one qualified calibration feature; and In response to the deposition depth of the first filling layer reaching the preset depth, the process conditions are changed, and the second precursor is used to perform conformal deposition on the first filling layer to form a second filling layer above the first filling layer.

2. The feature filling method according to claim 1, characterized in that: The step of changing the process conditions in response to the deposition depth of the first filling layer reaching a preset depth, and performing conformal deposition on the first filling layer using a second precursor to form a second filling layer above the first filling layer comprises: In response to the deposition depth of the first filling layer not reaching the preset depth, continuing to deposit the first filling layer; and In response to the deposition depth of the first filling layer reaching the preset depth, the process conditions are changed, and the second precursor is used to perform conformal deposition on the first filling layer to form the second filling layer above the first filling layer.

3. The feature filling method according to claim 1, characterized in that: The step of determining the preset depth according to the curvature of the sidewall line of the at least one qualified calibration feature comprises: Taking the bottom of the qualified calibration feature as the starting position, the sum of the depths of the seed layer and the first filling layer as the first preset depth; or The upper surface of the seed layer within the qualified calibration feature is taken as the starting position, and the depth of the first filling layer is taken as the second preset depth.

4. The feature filling method according to claim 3, characterized in that: Taking the bottom of the qualified calibration feature as the starting position, the first preset depth corresponding to the bending degree threshold is in the range of 30% to 40% of the total depth of the qualified calibration feature.

5. The feature filling method according to claim 3, characterized in that: Taking the upper surface of the seed layer within the qualified calibration feature as the starting position, the second preset depth corresponding to the bending degree threshold is in the range of 20% to 30% of the total depth of the qualified calibration feature.

6. The feature filling method according to claim 1, characterized in that: The first precursor and the second precursor are precursors of the same metal.

7. The feature filling method according to claim 6, characterized in that: The first precursor and the second precursor are both molybdenum-containing precursors, and the molybdenum-containing precursor is molybdenum chloride or molybdenum oxychloride. The number of atoms of chlorine in the first molybdenum precursor is greater than the number of atoms of chlorine in the second molybdenum precursor.

8. The feature filling method according to claim 7, characterized in that: The seed layer is made of metal nitride, and the metal nitride includes any one or more combinations of titanium nitride, molybdenum nitride, tungsten nitride, tungsten carbonitride, and tantalum nitride.

9. The feature filling method according to claim 7, characterized in that: In the process conditions, the process temperature range of the first molybdenum precursor deposition is 400°C to 500°C, and the process temperature range of the second molybdenum precursor deposition is 500°C to 600°C.

10. The feature filling method according to claim 1, characterized in that: The filling method further comprises: In response to the second filling layer completing the filling of each of the features, the second precursor continues to be introduced until the second filling layer covers the openings of each of the features.

11. A buried word line structure, characterized in that: include: A substrate comprising a plurality of spaced features, wherein each of the features comprises a seed layer having a deposition selectivity, the seed layer being located at a bottom of the feature; A first filling layer is disposed above the seed layer, wherein the first filling layer is obtained by selectively depositing a first precursor on the seed layer in the feature from bottom to top; and A second filling layer is arranged above the first filling layer, and the second filling layer is obtained by conformally depositing a second precursor on the first filling layer after the deposition depth of the first filling layer reaches a preset depth, wherein the preset depth is determined based on a threshold value of the curvature of the sidewall line of the feature, and the step of calibrating the preset depth of the feature includes: preparing a plurality of calibration features, wherein the calibration features have a bottom and a sidewall, and the bottom has a seed layer; selectively depositing the first precursor inside each of the calibration features, and conformally depositing the second precursor on the formed first filling layer to form a second filling layer above the first filling layer; and determining the curvature of the sidewall line of each of the calibration features according to a sidewall line curvature formula, wherein the sidewall line curvature formula is as follows: LB represents the curvature of the sidewall line, a i represents the distance between the center lines of the upper ends of the sidewalls between the i-th calibration feature and the i+1-th calibration feature before the deposition process is performed, c i represents the distance between the center lines of the upper ends of the side walls between the ith calibration feature and the (i+1)th calibration feature after the deposition process is completed, and n represents the number of the calibration features; according to a preset bending degree threshold, determining at least one calibration feature of qualified quality; and determining the preset depth according to the bending degree of the side wall line of the at least one calibration feature of qualified quality.

12. A feature filling system, characterized in that: include: A reaction chamber, in which a substrate including a plurality of spaced features to be filled with features is placed, wherein each of the features includes a seed layer with deposition selectivity, and the seed layer is located at the bottom of the feature; A first precursor source, connected to the reaction chamber, to provide a first precursor into the reaction chamber; A second precursor source connected to the reaction chamber to provide a second precursor into the reaction chamber; and A controller is connected to the first precursor source and the second precursor source, and is configured to: turn on the first precursor source, introduce the first precursor into the reaction chamber, so that the first precursor is selectively deposited from bottom to top on the seed layer in the feature to form a first filling layer above the seed layer, and in response to the deposition depth of the first filling layer reaching a preset depth, change the process conditions in the reaction chamber, turn off the first precursor source, and turn on the second precursor source, so that the second precursor is conformally deposited on the first filling layer to form a second filling layer above the first filling layer. A filling layer, wherein the preset depth is determined based on a threshold value of a curvature of a sidewall line of the feature, and the step of calibrating the preset depth of the feature comprises: preparing a plurality of calibration features, wherein the calibration features have a bottom and a sidewall, and the bottom has a seed layer; selectively depositing the first precursor inside each of the calibration features, and conformally depositing the second precursor on the formed first filling layer to form a second filling layer above the first filling layer; and determining the curvature of the sidewall line of each of the calibration features according to a sidewall line curvature formula, wherein the sidewall line curvature formula is as follows: LB represents the curvature of the sidewall line, a i represents the distance between the center lines of the upper ends of the sidewalls between the i-th calibration feature and the i+1-th calibration feature before the deposition process is performed, c i represents the distance between the center lines of the upper ends of the side walls between the ith calibration feature and the (i+1)th calibration feature after the deposition process is completed, and n represents the number of the calibration features; and determining at least one calibration feature of qualified quality according to a preset bending degree threshold; And the preset depth is determined according to the curvature degree of the side wall line of the at least one qualified calibration feature.

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