Tungsten deposition process and plasma equipment

Abstract

The invention discloses a tungsten deposition process and plasma equipment, and the deposition process comprises the steps: providing a substrate with a sunken structure, the sunken structure comprises a first part and a second part, the first part is located at the upper part of the second part, and the feature size of the first part is smaller than that of the second part; a first deposition step: depositing a first deposition layer on the first part and the second part; the first deposition layer at least comprises a first tungsten material layer and a second tungsten material layer; a treatment step: introducing a treatment gas into the surface of the substrate, and controlling the pressure and / or flow of the treatment gas until the first tungsten material layer of the first part is etched and exposed; and a second deposition step: depositing a second deposition layer in the treated sunken structure, so that at least partial region of the sunken structure is filled with tungsten. According to the tungsten deposition process, the sunken structure can be filled, and no gap exists.

Description

Technical Field

[0001] This invention relates to the field of semiconductors, and more specifically to a tungsten deposition process and plasma equipment. Background Technology

[0002] Chemical vapor deposition (CVD) is a commonly used metallization process in semiconductor via filling manufacturing. As the process becomes more advanced, for example in logic and memory processes, the feature size of semiconductor devices is getting smaller and smaller.

[0003] Tungsten filling involves inserting tungsten into feature areas, such as recessed structures. However, for recessed structures with small feature sizes, premature closure often occurs at the top opening during the tungsten filling process, resulting in multiple gaps within the recessed structure and thus defects where the feature area cannot be fully filled. Furthermore, if there are too many or too high gaps, they will be exposed during subsequent chemical mechanical planarization (CMP) treatment. CMP slurry may seep into the gaps and erode the tungsten filling layer, leading to the loss of tungsten filler material and significantly reducing the electrical performance and lifespan of semiconductor devices.

[0004] Conventional chemical vapor deposition (CVD) techniques for tungsten filling are no longer sufficient to meet the process requirements of production. Summary of the Invention

[0005] The purpose of this invention is to overcome the defect that when substrates with small feature sizes are subjected to tungsten deposition processes, the top opening of the recessed structure is prone to premature closure or gaps, resulting in the recessed structure not being filled.

[0006] To achieve the above objectives, the present invention provides a tungsten deposition process, comprising:

[0007] A substrate is provided, the substrate including a recessed structure, the recessed structure including a first part and a second part, the first part being located above the second part, and the feature size of the first part being smaller than the feature size of the second part;

[0008] First deposition step: Depositing a first deposition layer in the first and second portions of the recessed structure of the substrate; the first deposition layer comprises at least a first tungsten material layer and a second tungsten material layer deposited on the surface of the first tungsten material layer;

[0009] Processing steps: A processing gas is introduced into the surface of the substrate, and the processing gas etches the first deposited layer. The pressure and / or flow rate of the processing gas are controlled until the first tungsten material layer of the first portion of the recessed structure is exposed. The thickness reduction of the first deposited layer in the first portion is greater than the thickness reduction of the first deposited layer in the second portion. The processing gas is a gas containing fluorine / chlorine atoms and at least one of carbon, sulfur, nitrogen, hydrogen, or oxygen atoms.

[0010] Second deposition step: Deposit a second deposition layer in the recessed structure after the processing steps, such that at least a portion of the recessed structure is filled with tungsten.

[0011] Optionally, the processing gas is selected from one or a mixture of SF6, NF3, HCl, fluorocarbons, fluorohydrocarbons, fluorooxycarbons, chlorinated carbons, chlorinated hydrocarbons, chlorinated oxycarbons, and chlorinated oxycarbons.

[0012] Optionally, the pressure of the processing gas is not higher than 0.5 Torr.

[0013] Optionally, the flow rate of the processed gas is not higher than 50 sccm.

[0014] Optionally, the processing step takes 0 to 180 seconds.

[0015] Optionally, the method of introducing the processing gas includes continuous introduction or pulsed introduction.

[0016] Optionally, when the processing gas is continuously introduced, the duration of the processing gas introduction is greater than or equal to 3 seconds.

[0017] Optionally, when the processing gas is pulsed, the time of the processing gas being introduced in a single pulse cycle is greater than or equal to 0.5s.

[0018] Optionally, the processing gas is excited in the chamber of a remote plasma source into a fluorine / chlorine-containing plasma and a plasma containing at least one of carbon, sulfur, nitrogen, hydrogen, or oxygen. The fluorine / chlorine-containing plasma and the plasma containing at least one of carbon, sulfur, nitrogen, hydrogen, or oxygen annihilate charges through a pipe to form fluorine / chlorine-containing free radicals and free radicals containing at least one of carbon, sulfur, nitrogen, hydrogen, or oxygen. The free radicals react with at least a portion of the first deposition layer deposited within the recessed structure to form a tungsten growth inhibition zone.

[0019] Optionally, the process pressure range for the first deposition step is 10 Torr to 90 Torr;

[0020] The process pressure range for the aforementioned processing steps is 5 Torr to 30 Torr;

[0021] The process pressure range for the second deposition step is 10 Torr to 90 Torr.

[0022] Optionally, in the first deposition step, the thickness of the first deposition layer deposited in both the first portion and the second portion is less than 50 angstroms.

[0023] Optionally, the first deposition step and the second deposition step employ at least one of atomic layer deposition (ALD) technology, pulse deposition technology, atomic layer deposition (ALD) technology, or chemical vapor deposition (CVD) technology.

[0024] Optionally, the processing steps and the second deposition step are repeated in a loop, so that more of the depression structure is filled.

[0025] Optionally, the first tungsten material layer has an amorphous structure, and the second tungsten material layer has a polycrystalline structure.

[0026] Optionally, the aspect ratio of the recessed structure is less than 10:1.

[0027] Optionally, the recessed structure is at least one of a pore structure or a groove structure.

[0028] The present invention also provides a plasma device, comprising:

[0029] reaction chamber;

[0030] The base, located within the reaction chamber, is used to support the substrate;

[0031] A remote plasma source is used, in which the processing gas is excited into plasma within the chamber of the remote plasma source, and the plasma annihilates charges through a pipe to form free radicals, which then enter the reaction chamber to process the substrate.

[0032] The controller is configured to perform the tungsten deposition process described above.

[0033] Compared with the prior art, the beneficial effects of the present invention include at least the following:

[0034] The tungsten deposition process of the present invention fills a recessed structure comprising a first part and a second part with tungsten. The first part is located above the second part, and the feature size of the first part is smaller than that of the second part. The deposition process includes a first deposition step, a processing step, and a second deposition step. In the first deposition step, a first deposition layer of a certain thickness is deposited on the entire recessed structure. The first deposition layer comprises a first tungsten material layer and a second tungsten material layer. It was found that in the first deposition step, the thicker the first deposition layer, the greater the delay in the growth of subsequent tungsten material layers in the tungsten growth inhibition zone after the processing step, exhibiting a pattern of first increasing and then rapidly decreasing. This indicates that the thickness of the first deposition layer is related to the delayed growth time of the tungsten growth inhibition zone. Furthermore, the thickness of the first deposition layer deposited on both the first part and the second part of the recessed structure is less than 50 angstroms, thereby increasing the delayed growth time of the tungsten growth inhibition zone.

[0035] In the processing steps, by controlling the pressure and / or flow rate of the processing gas, the amount of each free radical is adjusted, leveraging the dual effects of etching and inhibition by the free radicals. This allows the fluorine / chlorine-containing free radicals in the processing gas to completely etch away the second tungsten material layer in the first part until the first tungsten material layer is exposed, and the second part etches away a portion of the second tungsten material layer, thereby increasing the top opening of the recessed structure. Free radicals in the processing gas containing at least one of carbon, sulfur, nitrogen, hydrogen, or oxygen form surface bonds on the surface of the first deposition layer near the top opening of the recessed structure. The area where surface bonds are formed delays the growth of subsequent tungsten material, creating a tungsten growth inhibition zone at the top opening of the recessed structure. This makes the growth inhibition effect of the first part of the recessed structure greater than that of the second part, extending the delayed growth time at the top opening of the recessed structure. Subsequent tungsten material is preferentially deposited in the second part of the recessed structure until the recessed structure is filled. The tungsten deposition process of this invention is applicable to recessed structures with a low aspect ratio and a bottleneck shape with a narrow first part and a wide second part, avoiding premature closure or gaps in the recessed structure. Attached Figure Description

[0036] Figure 1 This is a partial structural diagram of a semiconductor substrate with a high aspect ratio.

[0037] Figure 2 This is a schematic diagram of a tungsten deposition process performed on a semiconductor substrate with a high aspect ratio structure in one processing step.

[0038] Figure 3 This is a partial structural diagram of a semiconductor substrate with a bottleneck-shaped recessed structure that is narrow at the top and wide at the bottom, according to the present invention.

[0039] Figure 4 This is a schematic diagram of a tungsten deposition process according to the present invention.

[0040] Figure 5 This is a schematic diagram showing the relationship between the deposition thickness of tungsten material and the delayed growth time of the tungsten growth inhibition zone.

[0041] Figure 6 This is a simplified cyclic diagram of a tungsten deposition process according to the present invention.

[0042] Figure 7 This is a partial structural diagram of a semiconductor substrate with a bottleneck-shaped recessed structure that is narrow at the top and wide at the bottom, after undergoing the tungsten deposition process of the present invention.

[0043] Wherein, 100-substrate, 1a-first part, 1b-second part, 101-material layer, 102-recessed structure, 103-barrier layer, 201-tungsten growth inhibition region, 202-first tungsten material layer, 203-second tungsten material layer, 205-gap. Detailed Implementation

[0044] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] In the description of this invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0046] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0047] It should be noted that the accompanying drawings are all in a very simplified form and use non-precise ratios, and are only used to facilitate and clarify the illustration of the embodiments of the present invention.

[0048] The first part described in this invention refers to the upper part of the recessed structure, and the second part refers to the lower part of the recessed structure. In some embodiments, the term "upper half" is used to describe the "first part," and the term "lower half" is used to describe the "second part." It should be noted that "upper half" and "lower half" do not impose a fixed dimensional limitation on the height of the first and second parts of the recessed structure. The terms "upper half" and "lower half" should be interpreted broadly. For example, the "upper half" can occupy half, one-third, or two-thirds of the height of the entire recessed structure. The terms "upper half" and "lower half" are used merely for descriptive convenience and should not be used to limit their dimensions.

[0049] In the process of depositing tungsten in the feature areas of a substrate, a tungsten-containing precursor, a reducing gas, and a carrier gas are typically introduced. Through conventional deposition processes, the tungsten-containing precursor and reducing gas are deposited within the feature areas, thereby forming a tungsten material layer. For example... Figure 1 The diagram shows a partial structural schematic of a semiconductor substrate 100 with a high aspect ratio. Using a conventional deposition process, compared to the bottom of the recessed structure 102, more tungsten material tends to be deposited near the top opening of the recessed structure 102, forming a protrusion at the top opening. As the deposition process continues, the protrusion gradually grows, leading to the premature closure of the top opening of the recessed structure 102, resulting in a large gap within the recessed structure 102.

[0050] In order to improve the deposition effect of the tungsten material layer, an attempt was made to treat the recessed structure 102 to prevent the top opening area of ​​the recessed structure 102 from being pinched off during subsequent deposition.

[0051] As an example, such as Figure 2 As shown, during the tungsten filling process of the recessed structure 102, a tungsten material layer is first deposited inside the recessed structure 102 (on the barrier layer 103), and then a processing gas is introduced to treat the surface of the tungsten material layer. The tungsten material layer in the top opening region of the recessed structure 102 can be etched by fluorine / chlorine free radicals in the processing gas to enlarge the size of the top opening region and prevent premature closure of the recessed structure 102 in subsequent processes. Simultaneously, surface bonds can be formed on the surface of the tungsten material layer by free radicals containing at least one of carbon, sulfur, nitrogen, hydrogen, or oxygen in the processing gas. The area where surface bonds are formed delays the growth of the tungsten material layer in the second deposition step, forming a tungsten material layer deposition delay region, i.e., a tungsten growth inhibition region 201, on the sidewall of the recessed structure 102. Figure 2 (The dotted region on the sidewall of the recessed structure 102). The presence of this surface bond will delay / inhibit the deposition of subsequent tungsten material layers at this location, but will not form an observable new thin film and will not affect the electrical properties of the semiconductor substrate 100.

[0052] However, the applicant team found that using the aforementioned conventional processing techniques did not yield satisfactory results when treating some structures with special characteristics. For example... Figure 3 As shown, when the above processing technology is applied to the recessed structure 102 with a low aspect ratio and a narrow top and wide bottom, the top opening of the recessed structure 102 is often narrow, and it is still easy for it to close prematurely or have gaps 205, which will result in the recessed structure 102 not being able to be filled.

[0053] Specifically, such as Figure 3 The image shows a substrate 100 with a bottleneck-shaped recessed structure 102, narrow at the top and wide at the bottom. The recessed structure 102 includes an upper half 1a (i.e., the first part) and a lower half 1b (i.e., the second part). After a first deposition layer is deposited in the recessed structure 102, the recessed structure 102 is processed: a processing gas is introduced into the surface of the substrate 100 to process the surface of the first deposition layer. The processing gas etches the first deposition layer in the top opening region of the recessed structure 102. Simultaneously, the processing gas forms surface bonds on the surface of the first deposition layer, forming a tungsten growth inhibition region at the top opening of the recessed structure 102. After the processing step is completed, a second deposition layer is deposited in the recessed structure 102. Due to the presence of the tungsten growth inhibition region, tungsten material is preferentially deposited on the surface of the first deposition layer in the lower half of the recessed structure 102. However, since the top opening area of ​​the recessed structure 102 is small, as the thickness of the tungsten material layer increases, the top opening of the recessed structure 102 is still prone to premature closure or gaps 205, resulting in poor tungsten filling effect.

[0054] To address the technical problem in tungsten deposition processes where the top opening of a bottleneck-shaped recessed structure 102 with small feature dimensions and a narrow top and wide bottom tends to close prematurely or form gaps, preventing the recessed structure 102 from being fully filled, this invention unexpectedly discovered that in the first deposition step, as the first deposition layer becomes thicker, the time for delayed growth of subsequent tungsten material layers in the tungsten growth inhibition zone initially increases and then decreases sharply. This is mainly due to the different crystal phase structures of different tungsten material layers. Compared to the polycrystalline structure of the tungsten host layer, the amorphous tungsten nucleation layer is more likely to form a tungsten growth inhibition zone, thus significantly increasing the delayed growth time at that location. Therefore, when processing the bottleneck-shaped recessed structure 102, this invention aims to extend the delayed growth time at the top opening of the recessed structure 102, thereby ensuring that subsequent tungsten material layers are preferentially deposited in the lower half of the recessed structure 102, thus preventing closure or gaps at the top opening of the recessed structure 102.

[0055] Specifically, the present invention provides a tungsten deposition process that achieves "non-conformal suppression" by generating different delayed growth times in the depth direction based on the differences in the crystal phase structure of different tungsten material layers: by controlling the pressure and / or flow rate of the processing gas, the top opening of the recessed structure 102 is enlarged by the etching effect of free radicals, and the delayed growth time at the top opening of the recessed structure 102 is extended by the suppression effect of free radicals, so as to finally fill the recessed structure 102, thereby avoiding premature closure or gaps at the top opening of the recessed structure 102.

[0056] In this invention, both the first portion 1a and the second portion 1b of the recessed structure 102 of the substrate 100 are deposited with a first deposition layer, which contains at least two tungsten material layers with different crystal phase structures. In the processing gas, fluorine / chlorine-containing free radicals etch the first deposition layer, enlarging the top opening of the recessed structure 102; free radicals containing carbon, sulfur, nitrogen, hydrogen, or oxygen inhibit tungsten growth in the first deposition layer. By controlling the pressure and / or flow rate of the free radicals, the etching rate of the first portion 1a is greater than that of the second portion 1b, causing the second tungsten material layer of the first portion 1a of the recessed structure 102 to be completely etched away until the first tungsten material layer is exposed, while the second portion 1b of the recessed structure 102 has a portion of its second tungsten material layer etched away, retaining both the first tungsten material layer and a portion of the second tungsten material layer. The first tungsten material layer and the second tungsten material layer have different crystal phase structures. Therefore, in the processing steps, the delayed growth time of the first tungsten material layer is greater than that of the second tungsten material layer. In the processing steps, since the first tungsten material layer has a stronger inhibitory effect, in the second deposition step, the deposition rate of the first part 1a of the recessed structure 102 is less than that of the second part 1b, so that the subsequent tungsten material is preferentially deposited on the surface of the second tungsten material layer in the second part 1b.

[0057] By controlling the pressure and / or flow rate of free radicals according to this invention, the amount of different types of free radicals is adjusted, simultaneously exerting the dual effects of free radical etching and inhibition. This results in different delayed growth effects in the first part 1a and the second part 1b of the recessed structure 102, thereby achieving different deposition rates in the subsequent second deposition step. This increases the top opening size of the recessed structure 102 and also ensures that the delayed growth time of the first part 1a is greater than that of the second part 1b. This results in a longer delayed growth time at the top opening of the recessed structure 102, causing subsequent tungsten material to preferentially deposit in the second part 1b of the recessed structure 102, avoiding premature closure or gaps at the top opening of the recessed structure 102.

[0058] like Figure 3 , 4As shown, the tungsten deposition process provided by the present invention includes:

[0059] Step S1: Provide a substrate 100, the substrate 100 including a recessed structure 102, the recessed structure 102 including a first part 1a and a second part 1b, the first part 1a being located above the second part 1b, and the feature size of the first part 1a being smaller than the feature size of the second part 1b.

[0060] It is understood that, depending on the actual process, the heights of the first portion 1a and the second portion 1b of the recessed structure 102 may be the same or different. For example, the height of the first portion 1a may be equal to the height of the second portion 1b; the height of the first portion 1a may be greater than the height of the second portion 1b; or the height of the first portion 1a may be less than the height of the second portion 1b. In practical applications, due to differences in different processes, the cross-sectional shapes of the first portion 1a and the second portion 1b may be circular, square, or other irregular shapes. The feature dimensions include not only the aspect ratio but also the lateral dimension. In some embodiments, the tungsten deposition process is applied to the deposition of tungsten in a low aspect ratio structure. The low aspect ratio structure may be a recessed structure 102 with an aspect ratio less than 10:1, optionally, with an aspect ratio of 3:1 or 5:1. The critical dimension of the top opening of the recessed structure 102 may be between 20 nm and 500 nm (e.g., the lateral diameter at the top opening). Optionally, the recessed structure 102 may be a hole-like structure or a groove-like structure.

[0061] Step S2, First Deposition Step: A first deposition layer is deposited in the first portion 1a and the second portion 1b of the recessed structure 102 of the substrate 100; the first deposition layer includes at least a first tungsten material layer and a second tungsten material layer deposited on the surface of the first tungsten material layer.

[0062] In the first deposition step, one or more reducing agents and a tungsten-containing precursor are simultaneously introduced into the chamber. Using a near-atomic layer deposition process, the reducing agent and the tungsten-containing precursor first form a tungsten nucleation layer within the first portion 1a and the second portion 1b of the recessed structure 102. Subsequently, a tungsten bulk layer is deposited on the tungsten nucleation layer. The tungsten nucleation layer is typically a thin, conformal layer, usually with an amorphous structure, which facilitates the subsequent deposition of the tungsten bulk layer, which is typically polycrystalline. Optionally, the tungsten-containing precursor is tungsten hexafluoride (WF6), and the reducing agent is hydrogen (H2). Of course, the types of tungsten-containing precursor and reducing agent are not limited to the above; other reagents can also be used. For example, the tungsten-containing precursor can also be tungsten hexachloride (WCl6), and the reducing agent can also be silane, diborane, etc., as long as they achieve the same deposition effect.

[0063] Optionally, the process pressure range of the first deposition step is 10 Torr to 90 Torr, and the process temperature range is 300℃ to 400℃. In addition to using an atomic layer deposition-like process, the first deposition step can also employ any one of chemical vapor deposition (CVD), pulse deposition, or atomic layer deposition processes.

[0064] In the first deposition step, the thickness of the first deposited layer formed in the initial deposition step is crucial, as the thickness of the first deposited layer directly affects the filling rate of tungsten material within the entire recessed structure 102. The first deposited layer should not be too thin to prevent the processing gas from damaging the barrier layer beneath it during the processing steps; the first deposited layer should also not be too thick because, for the low aspect ratio recessed structure 102, its top opening is inherently narrow. If too thick a layer of tungsten material is deposited in the initial first deposition step, on the one hand, it is equivalent to reducing the size of the top opening of the recessed structure 102, thereby affecting the diffusion of gas during subsequent deposition and thus affecting the filling effect of the recessed structure 102; on the other hand, it will greatly prolong the processing time of the processing steps.

[0065] The delayed growth time is related to the thickness of the tungsten material layer deposited in the first deposition step. The tungsten growth inhibition zone first increases the time required to delay the growth of the subsequent tungsten bulk layer, and then decreases sharply. For example... Figure 5 As shown, taking the delayed growth of the tungsten growth inhibition zone generated at the top opening of the concave structure 102 as an example, the thickness of the first deposition layer deposited in the first deposition step is used as the horizontal axis, and the delayed growth time is used as the vertical axis. Figure 5 In the first deposition step, when only the tungsten nucleus layer is deposited and the tungsten bulk layer has not yet begun deposition, the thickness of the tungsten nucleus layer is approximately... At this point, the thickness of the tungsten bulk layer is 0. The delayed growth time in the tungsten growth inhibition zone initially shows an increasing trend, meaning the delayed growth time becomes longer and longer, reaching approximately [a certain value] when the thickness of the tungsten nucleation layer is [a certain value]. At this point, the delayed growth time reaches its maximum; as the tungsten material layer continues to deposit, the delayed growth time in the tungsten growth inhibition zone begins to decrease sharply, for example, when the thickness of the first deposited layer is approximately... At this point, the delayed growth time has decreased to 100 seconds. In a preferred embodiment, the thickness of the first deposition layer deposited in the first portion 1a and the second portion 1b of the recessed structure 102 is the same, both less than [a certain value].

[0066] It can be seen that the thickness of the first deposition layer is related to the delayed growth time caused by the tungsten growth inhibition zone.

[0067] Step S3, Treatment: A treatment gas is introduced into the surface of the substrate 100, and the treatment gas etches the first deposited layer. The pressure and / or flow rate of the treatment gas are controlled until the first tungsten material layer of the first portion 1a of the recessed structure 102 is exposed. The thickness of the first deposited layer of the first portion 1a reduced by etching is greater than the thickness of the first deposited layer of the second portion 1b reduced by etching. The treatment gas is a gas containing fluorine / chlorine atoms and at least one of carbon, sulfur, nitrogen, hydrogen or oxygen atoms.

[0068] After the first deposition step is completed, a processing gas is introduced into the chamber to process the first deposition layer deposited in the first deposition step. The processing gas is selected from one or a mixture of SF6, NF3, HCl, fluorocarbons (e.g., CF4, CHF3, C2F4), fluorohydrocarbons, fluorooxycarbons, chlorinated carbons, chlorinated hydrocarbons, and chlorinated oxycarbons. That is, the processing gas is a gas containing fluorine / chlorine and at least one of carbon, sulfur, nitrogen, hydrogen, or oxygen, or a vaporized precursor.

[0069] In the processing step, the processing gas is introduced into the chamber of a remote plasma source (RPS), where it is excited into a plasma containing fluorine / chlorine gas and at least one of carbon, sulfur, nitrogen, hydrogen, or oxygen. The fluorine / chlorine plasma and the plasma containing at least one of carbon, sulfur, nitrogen, hydrogen, or oxygen annihilate charges through a pipe, forming fluorine / chlorine free radicals and free radicals containing at least one of carbon, sulfur, nitrogen, hydrogen, or oxygen. In this embodiment, the processing gas is preferably NF3 gas. NF3 gas is excited into a nitrogen / fluorine plasma in the chamber of the remote plasma source, and the nitrogen / fluorine plasma annihilates charges through a pipe, forming fluorine-containing free radicals and nitrogen-containing free radicals. The fluorine-containing free radicals have an etching effect, reacting with the tungsten material layer to generate volatile tungsten hexafluoride, etching the first deposition layer. The nitrogen-containing free radicals have an inhibitory effect, forming a tungsten growth inhibition zone with at least a portion of the first deposition layer deposited on the sidewall of the recessed structure, delaying the deposition time of the subsequent tungsten bulk layer.

[0070] By controlling the pressure and / or flow rate of the processing gas, the amounts of nitrogen-containing free radicals and fluorine-containing free radicals can be adjusted, thereby leveraging the etching effect of fluorine-containing free radicals and the inhibition effect of nitrogen-containing free radicals. This allows for achieving the processing effect required by the actual process at the top opening of the recessed structure 102.

[0071] When the pressure and / or flow rate of the processing gas is high, there are more fluorine-containing free radicals, and the processing effect is mainly etching. In one embodiment, the processing gas is NF3. NF3 gas molecules collide more violently at the top of the recessed structure 102. During the collision process, a large amount of active components of the free radicals are lost. Therefore, the diffusion depth of nitrogen-containing and fluorine-containing free radicals into the second part 1b of the recessed structure 102 is limited, and the active free radicals are only adsorbed at the top opening of the first part 1a of the recessed structure 102. When the pressure and / or flow rate of NF3 is high, since there are more fluorine-containing free radicals, when the fluorine-containing free radicals etch the first deposition layer, they will partially remove or even eliminate the nitrogen-containing free radicals adsorbed on the surface of the first deposition layer. Therefore, the surface bonds formed between the nitrogen-containing free radicals and the tungsten material layer are reduced or even eliminated, and the inhibitory effect of the tungsten growth inhibition zone is weakened or even completely lost. Therefore, the processing effect is mainly etching at this time.

[0072] When the pressure and / or flow rate of the processing gas is low, there are more nitrogen-containing free radicals, and the processing effect is mainly suppression. In one embodiment, the processing gas is NF3. When the pressure and / or flow rate of NF3 is low, nitrogen-containing free radicals and fluorine-containing free radicals are adsorbed at the top opening of the first part 1a of the recessed structure 102. Although some of the fluorine-containing free radicals etch the first deposition layer at this time, there are more nitrogen-containing free radicals. A large number of nitrogen-containing free radicals react with the tungsten material layer to form surface bonds, thereby forming a tungsten growth inhibition zone. This delays the deposition of the tungsten material layer in the second deposition step in the top opening area of ​​the first part 1a of the recessed structure 102 and the sidewall area of ​​the recessed structure 102 near the top opening of the first part 1a at a certain depth.

[0073] During the processing steps, the processing gas causes a delay in tungsten growth in the tungsten growth inhibition zone. Since the tungsten bulk layer cannot be directly deposited on the barrier layer of the semiconductor substrate 100, a tungsten nucleus layer must be deposited first. The surface of this nucleus layer contains dangling bonds, which typically allow the tungsten bulk layer to adhere well to the nucleus layer for subsequent tungsten material growth. During the processing steps, free radicals of at least carbon, sulfur, nitrogen, hydrogen, or oxygen in the processing gas combine with the dangling bonds in the tungsten growth inhibition zone on the surface of the nucleus layer to form surface bonds. This prevents the tungsten bulk layer from combining with the dangling bonds in that region of the nucleus layer, thus delaying the deposition of the subsequent tungsten bulk layer at that location. If tungsten material needs to continue growing in the tungsten growth inhibition zone, dangling bonds need to be reformed here. For example, when depositing the tungsten bulk layer in the subsequent second deposition step, a certain reaction time (i.e., delayed growth time) is required to reform the dangling bonds here so that the tungsten bulk layer can be deposited subsequently. However, during this reaction time, the area outside the tungsten growth inhibition zone is depositing the tungsten bulk layer normally. Therefore, from the perspective of the tungsten material deposition of the entire depression structure 102, the processing gas will cause a tungsten growth delay of tens or even thousands of seconds in the tungsten growth inhibition zone.

[0074] Due to differences in crystal phase structure, the tungsten growth delay time varies depending on the tungsten material layer. Tungsten nucleation is a crucial step in the tungsten deposition process. During nucleation, a tungsten-containing precursor reacts with a reducing agent to form a thin tungsten nucleation layer, which serves as the growth point for the subsequent tungsten bulk layer. The tungsten nucleation layer and the tungsten bulk layer have different crystal phase structures. The tungsten nucleation layer is amorphous, lacking ordered long-distance arrangements of atoms or molecules, and exhibits isotropy (its properties are the same in all directions). The tungsten bulk layer is polycrystalline, consisting entirely of ordered long-distance arrangements of atoms or molecules. A repeating unit within the polycrystalline structure constitutes the entire polycrystalline structure, exhibiting anisotropy (its properties differ in different directions). Because during the processing steps, when the processing gas etches the first part 1a of the recessed structure 102 to expose the tungsten nucleus layer, the second part 1b of the recessed structure 102 is not yet exposed to the tungsten nucleus layer. Therefore, during the processing steps, the fluorine-containing free radicals and nitrogen-containing free radicals contact the tungsten nucleus layer and the tungsten bulk layer in the first part 1a and the second part 1b of the recessed structure 102, respectively. When the processing gas processes the recessed structure 102, because the tungsten nucleus layer is an amorphous structure, more free radicals are more likely to occupy the nucleation sites on the surface of the tungsten nucleus layer, making nucleation of the tungsten nucleus layer more difficult. Ultimately, this results in a certain difference in the density of nucleation sites between the tungsten nucleus layer and the tungsten bulk layer. Therefore, the inhibitory effect brought by the tungsten nucleus layer is greater than that brought by the tungsten bulk layer.

[0075] After the processing steps of this invention, the inhibition effect of the tungsten nucleation layer exposed in the first part of the recessed structure is greater than the inhibition effect of the tungsten body layer exposed in the second part. Therefore, the inhibition effect of the first part 1a of the recessed structure 102 is stronger than the inhibition effect of the second part 1b of the recessed structure 102, and the delayed growth time of the first part 1a of the recessed structure 102 is greater than the delayed growth time of the second part 1b of the recessed structure 102, that is, the delayed growth time at the top opening of the recessed structure 102 is extended. In some embodiments, the delayed growth time of the first part 1a of the recessed structure 102 reaches hundreds of seconds or even thousands of seconds, while the delayed growth time of the second part 1b of the recessed structure 102 is as short as tens of seconds.

[0076] The delay in tungsten growth is related not only to the crystal phase structure of different tungsten material layers, but also to the specific processes in the processing steps. It is understood that since the tungsten bulk layer in the first deposition layer is exposed on the outermost layer, the processing gas first contacts the tungsten bulk layer. When the fluorine / chlorine-containing free radicals in the processing gas etch the first deposition layers of the first part 1a and the second part 1b, by controlling the pressure and / or flow rate of the processing gas as described above, the processing gas etches until the tungsten nucleus layer of the first part 1a of the recessed structure 102 is exposed. The thickness reduction due to etching of the first deposition layer of the first part 1a is greater than the thickness reduction due to etching of the first deposition layer of the second part 1b. This results in the second part 1b containing not only the tungsten nucleus layer but also a portion of the tungsten bulk layer when the first part 1a is etched down to only the tungsten nucleus layer. Not only can the top opening of the recessed structure 102 be etched to enlarge the feature size of the top opening, but the growth delay time at the top opening can also be extended, so that more tungsten material is preferentially deposited in the second part 1b of the recessed structure 102, thereby realizing the downward movement and reduction of the gap in the recessed structure 102, and realizing the filling of the bottleneck-shaped recessed structure 102 that is narrow at the top and wide at the bottom.

[0077] With the internal pressure and flow rate of other inert gases within the cavity remaining constant, controlling the pressure and / or flow rate of the processing gas can control the concentration of free radicals at the top of the recessed structure 102, thereby controlling the treatment effect of free radicals within the recessed structure 102. Optionally, the process pressure range of the treatment step is 5 Torr to 30 Torr, the pressure of the processing gas is not higher than 0.5 Torr, the flow rate is not higher than 50 sccm, and the treatment time is 0 to 180 s. It is understood that in practical applications, the above process parameters can be appropriately adjusted to obtain the best treatment effect.

[0078] In some embodiments, to achieve the suppression effect of "gradient delay" from top to bottom in the recessed structure 102, a continuous flow of processing gas can be used. The processing gas flow time should not be too short, because if the time is too short, the processing gas can only diffuse to the surface of the recessed structure 102, and it is difficult for the processing gas to diffuse into the middle and bottom of the recessed structure 102. For the middle and bottom of the recessed structure without processing gas flow, due to the lack of a tungsten growth suppression zone, more tungsten material will be directly deposited in the middle and bottom of the recessed structure 102 during the tungsten deposition process. Especially for the bottleneck-shaped recessed structure 102 that is narrow at the top and wide at the bottom, it is easy for the narrower first part to deposit tungsten material earlier, causing the top opening of the entire recessed structure 102 to "close" earlier, making it easy for gaps to appear in the wider second part. Optionally, the processing gas flow time is greater than or equal to 3 seconds.

[0079] In some embodiments, to maintain a good suppression effect at the top opening of the recessed structure 102 and prevent the processing gas from penetrating too deeply into the top opening of the recessed structure 102, a pulsed introduction method can be used to introduce the processing gas. To achieve the suppression effect at the top opening of the recessed structure 102, the actual process includes at least three pulse cycles. The time for introducing the processing gas in a single pulse cycle should not be too long, because the diffusion degree of the processing gas in the recessed structure 102 is proportional to the time of introduction. If the time for introducing the processing gas in a single pulse cycle is too long, it may lead to excessive suppression depth. Optionally, the time for introducing the processing gas in a single pulse cycle is greater than or equal to 0.5 s. On the other hand, pulsed introduction of the processing gas also helps to expand the diffusion range of the processing gas and contributes to the uniformity of substrate processing.

[0080] Step S4, Second Deposition Step (Deposition 2): A second deposition layer is deposited in the recessed structure 102 after the processing steps, such that at least a portion of the recessed structure 102 is filled with tungsten.

[0081] After the processing step is completed, a second deposition step is performed. In some embodiments, a tungsten bulk layer is deposited using chemical vapor deposition (CVD). One or more reducing agents and a tungsten-containing precursor are simultaneously introduced into the chamber. Through the CVD process, the reducing agent and the tungsten-containing precursor deposit a second-thickness tungsten bulk layer on the tungsten nucleation layer treated with the processing gas. Because the processing gas in the processing step contains at least one of the free radicals of carbon, sulfur, nitrogen, hydrogen, or oxygen, a tungsten growth inhibition zone is formed at a certain depth below the top opening of the treated recessed structure 102. In the second deposition step, the tungsten material is preferentially deposited on the second part 1b of the recessed structure 102, thereby achieving the downward movement, reduction, and eventual disappearance of the gaps within the recessed structure. Optionally, the tungsten-containing precursor is tungsten hexafluoride (WF6), and the reducing agent is hydrogen (H2). Of course, the types of tungsten-containing precursor and reducing agent are not limited to the above; other reagents can also be used, as long as they can achieve the same deposition effect. Optionally, the process pressure range of the second deposition step is 10 Torr to 90 Torr.

[0082] It should be noted that both the first and second deposition steps can employ at least one of chemical vapor deposition (CVD), atomic layer deposition (ALD), pulse deposition, or atomic layer deposition (ALD). The processes for the first and second deposition steps are not limited to those described above and can be adjusted according to actual process conditions or application requirements; this invention does not impose any limitations on these adjustments. In practical applications, a suitable deposition process can be selected between the first and second deposition steps based on process requirements and equipment conditions to form a first and second deposition layer that meets the actual needs. Optionally, the first deposition step can employ pulse deposition, and the second deposition step can employ CVD, i.e., the tungsten nucleus layer and the tungsten bulk layer use different deposition processes. The first and second deposition steps can be performed within the same chamber.

[0083] like Figure 6 As shown, in practical applications, the present invention does not limit the number of processing steps in the tungsten deposition process. During tungsten deposition, a single processing step can be performed to completely fill the recessed structure 102. It is understood that multiple processing steps can also be performed. In some embodiments, a cycle of a first deposition step – a processing step – a second deposition step can achieve continuous processing of the tungsten material layer at the top opening of the recessed structure 102. After one or more processing steps, the delayed growth time at the top opening is further extended, and more tungsten material is preferentially deposited in the second part 1b of the recessed structure 102 to reduce the gaps within the recessed structure 102. It is understood that for recessed structures with low aspect ratios, typically only one or two processing steps are needed to achieve a good filling effect. The tungsten deposition process described above can greatly improve filling efficiency and save process time and costs.

[0084] The present invention also provides a plasma device, comprising: a reaction chamber; a base located within the reaction chamber for supporting a substrate; a remote plasma source, wherein the processing gas is excited into plasma within the chamber of the remote plasma source, the plasma annihilates charges through a pipe to form free radicals, the free radicals enter the reaction chamber to process the substrate; and a controller configured to perform the aforementioned tungsten deposition process.

[0085] Example

[0086] This embodiment provides a tungsten deposition process, including:

[0087] Step S1: Provide a substrate, the substrate including a hole structure, the hole structure including an upper half and a lower half, the diameter of the upper half being smaller than the diameter of the lower half. The aspect ratio of the hole structure is 5:1, the diameter of the upper half of the hole structure is 20 nm, and the diameter of the lower half of the hole structure is 50 nm.

[0088] Step S2: First Deposition Step: A tungsten precursor and reducing gas are introduced into the substrate surface. The tungsten precursor is tungsten hexafluoride (WF6), and the reducing gas is hydrogen (H2) and diborane (B2H6). A near-atomic layer deposition (ALD) process is used to deposit a first deposition layer in the upper and lower halves of the pore structure. The first deposition layer comprises a tungsten nucleus layer deposited on the surface of the pore structure barrier layer and a tungsten bulk layer deposited on the surface of the tungsten nucleus layer. In the first deposition step, the process pressure is 10 Torr and the process temperature is 300°C. Through the first deposition step, a layer with a thickness of [thickness missing] is formed in both the upper and lower halves of the pore structure. The first sedimentary layer.

[0089] Step S3: Processing Step: NF3 gas is introduced into a remote plasma source (RPS). The NF3 gas is excited into fluorine-containing plasma and nitrogen-containing plasma within the chamber of the remote plasma source. The fluorine-containing plasma and nitrogen-containing plasma annihilate charges through pipes, forming fluorine-containing free radicals and nitrogen-containing free radicals. The partial pressure of the pipes introducing the fluorine-containing free radicals and nitrogen-containing free radicals is controlled to introduce fluorine-containing free radicals and nitrogen-containing free radicals onto the substrate surface. In this processing step, the process pressure is 20 Torr, the partial pressures of the pipes introducing the fluorine-containing free radicals and nitrogen-containing free radicals are 0.02 Torr and 0.06 Torr, respectively, and the flow rate of the NF3 gas does not exceed 50 sccm.

[0090] Step S4: Second Deposition Step: A tungsten-containing precursor (WF6) and a reducing gas (H2) are introduced onto the substrate surface. Chemical vapor deposition (CVD) is used to deposit a second deposition layer within the pore structure after the initial treatment. Because the upper and lower halves of the pore structure experience a "gradient delay" inhibition effect during the initial treatment, the growth delay time is longer in the upper half of the pore structure, and the second deposition layer preferentially deposits in the lower half of the pore structure. The process pressure in this second deposition step is 10 Torr.

[0091] Step S5: Repeat the processing step and the second deposition step in a loop until the pore structure is filled.

[0092] like Figure 7As shown, using the aforementioned tungsten deposition process, the gaps within the pore structure disappear, and the pore structure is completely filled. It can be seen that when the processing gas treats the pore structure, it completely etches away the upper half of the tungsten bulk layer, leaving only the tungsten nucleus layer. At this point, only a portion of the tungsten bulk layer is etched away in the lower half. Therefore, the lower half contains both the tungsten nucleus layer and a portion of the tungsten bulk layer. The structure of the tungsten film in the upper half tends towards an amorphous structure, while the tungsten film in the lower half, located deep within the recessed structure, retains a polycrystalline structure. At this time, the tungsten growth inhibition zone formed on the surface of the tungsten nucleus layer exerts an inhibitory effect, delaying the growth time of the subsequently deposited tungsten material layer. This indicates that when the tungsten material layer is thin or contains only the tungsten nucleus layer, the delayed growth time of the tungsten growth inhibition zone is longer. As the tungsten bulk layer is deposited, the thickness of the tungsten material layer increases, and the delayed growth time of the tungsten growth inhibition zone begins to shorten significantly.

[0093] In summary, during the first deposition step, a layer with a thickness less than [missing information] was deposited in both the first and second portions of the recessed structure. The first deposition layer comprises a first tungsten material layer and a second tungsten material layer with different crystal phase structures. In the processing steps, by controlling the pressure and / or flow rate of the processing gas, the top opening of the recessed structure 102 is enlarged using the etching effect of free radicals, and the delayed growth time at the top opening of the recessed structure 102 is extended using the inhibitory effect of free radicals, ultimately achieving the filling of the recessed structure 102, thereby avoiding premature closure or gaps at the top opening of the recessed structure 102. The tungsten deposition process of the present invention is applicable to bottleneck-shaped recessed structures with low aspect ratios and a narrower first part and a wider second part, preventing premature closure or gaps in the recessed structure.

[0094] Although the present invention has been described in detail through the preferred embodiments above, it should be understood that the above description should not be considered as a limitation of the present invention. Various modifications and substitutions to the present invention will be apparent to those skilled in the art after reading the above description. Therefore, the scope of protection of the present invention should be defined by the appended claims.

Claims

1. A tungsten deposition process, characterized in that, Include: A substrate is provided, the substrate including a recessed structure, the recessed structure including a first part and a second part, the first part being located above the second part, and the feature size of the first part being smaller than the feature size of the second part; First deposition step: Depositing a first deposition layer in the first and second portions of the recessed structure of the substrate; the first deposition layer comprises at least a first tungsten material layer and a second tungsten material layer deposited on the surface of the first tungsten material layer; Processing steps: A processing gas is introduced into the surface of the substrate, and the processing gas etches the first deposited layer. The pressure and / or flow rate of the processing gas are controlled until the first tungsten material layer of the first portion of the recessed structure is exposed. The thickness reduction of the first deposited layer in the first portion is greater than the thickness reduction of the first deposited layer in the second portion. The processing gas is a gas containing fluorine / chlorine atoms and at least one of carbon, sulfur, nitrogen, hydrogen, or oxygen atoms. Second deposition step: Deposit a second deposition layer in the recessed structure after the processing steps, such that at least a portion of the recessed structure is filled with tungsten.

2. The tungsten deposition process as described in claim 1, characterized in that, The processing gas is selected from one or a mixture of SF6, NF3, HCl, fluorocarbons, fluorohydrocarbons, fluorooxycarbons, chlorinated carbons, chlorinated hydrocarbons, chlorinated oxycarbons, and chlorinated oxycarbons.

3. The tungsten deposition process as described in claim 1, characterized in that, The pressure of the processed gas is not higher than 0.5 Torr.

4. The tungsten deposition process as described in claim 1, characterized in that, The flow rate of the processed gas is not higher than 50 sccm.

5. The tungsten deposition process as described in claim 1, characterized in that, The processing time for each step is 0–180 seconds.

6. The tungsten deposition process as described in claim 1, characterized in that, The gas to be processed can be introduced in either a continuous flow or a pulsed flow.

7. The tungsten deposition process as described in claim 6, characterized in that, When the processing gas is continuously introduced, the duration of the processing gas introduction is greater than or equal to 3 seconds.

8. The tungsten deposition process as described in claim 6, characterized in that, When the processing gas is pulsed, the time of the processing gas being introduced in a single pulse cycle is greater than or equal to 0.5s.

9. The tungsten deposition process as described in claim 1, characterized in that, The processing gas is excited in the chamber of a remote plasma source into a fluorine / chlorine-containing plasma and a plasma containing at least one of carbon, sulfur, nitrogen, hydrogen, or oxygen. The fluorine / chlorine-containing plasma and the plasma containing at least one of carbon, sulfur, nitrogen, hydrogen, or oxygen annihilate charges through a pipe to form fluorine / chlorine-containing free radicals and free radicals containing at least one of carbon, sulfur, nitrogen, hydrogen, or oxygen. The free radicals react with at least a portion of the first deposition layer deposited within the recessed structure to form a tungsten growth inhibition zone.

10. The tungsten deposition process as described in claim 1, characterized in that, The process pressure range for the first deposition step is 10 Torr to 90 Torr; The process pressure range for the aforementioned processing steps is 5 Torr to 30 Torr; The process pressure range for the second deposition step is 10 Torr to 90 Torr.

11. The tungsten deposition process as described in claim 1, characterized in that, In the first deposition step, the thickness of the first deposition layer deposited in both the first part and the second part is less than 50 angstroms.

12. The tungsten deposition process as described in claim 1, characterized in that, The first deposition step and the second deposition step employ at least one of atomic layer deposition (ALD) technology, pulse deposition technology, atomic layer deposition (ALD) technology, or chemical vapor deposition (CVD) technology.

13. The tungsten deposition process as described in claim 1, characterized in that, The processing steps and the second deposition step are repeated in a loop, so that more of the depression structure is filled.

14. The tungsten deposition process as described in claim 1, characterized in that, The first tungsten material layer has an amorphous structure, and the second tungsten material layer has a polycrystalline structure.

15. The tungsten deposition process as described in claim 1, characterized in that, The depth-to-width ratio of the recessed structure is less than 10:

1.

16. The tungsten deposition process as described in claim 1, characterized in that, The recessed structure is at least one of a pore-like structure or a groove-like structure.

17. A plasma device, characterized in that, include: reaction chamber; The base, located within the reaction chamber, is used to support the substrate; A remote plasma source is used, in which the processing gas is excited into plasma within the chamber of the remote plasma source, and the plasma annihilates charges through a pipe to form free radicals, which then enter the reaction chamber to process the substrate. A controller configured to perform the tungsten deposition process as described in any one of claims 1 to 16.

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