TWI627676B - Void free tungsten fill in different sized features - Google Patents

Abstract

Methods are provided herein for depositing tungsten into features of different sizes on a substrate. The method includes depositing a first body tungsten layer into the features, etching the deposited tungsten, depositing a second body tungsten, the system is interrupted to process the tungsten after the smaller features are completely filled, and After the smaller, smoother tungsten grains are deposited in the large features, the deposition of the second body layer continues. The method also includes depositing tungsten in several cycles of deposition-etch-deposition, where each cycle targets a group of features of similar size and uses etching chemicals for that group; and from the smallest feature to The largest feature is deposited. Deposition using the methods described herein produces smaller, smoother grains, which are features with a wide range of sizes within the substrate using gap-free fillers.

Description

Hole-free tungsten filler in different size features

The present invention relates to void-free tungsten fillers in features of different sizes.

The deposition of tungsten-containing materials using chemical vapor deposition (CVD) technology is an integral part of many semiconductor manufacturing processes. These materials can be used for horizontal interconnects, vias between adjacent metal layers, contact windows between the first metal layer and components on the silicon substrate, and high aspect ratio features. In a conventional deposition process, a substrate located in a deposition chamber is heated to a predetermined processing temperature, and a thin layer of tungsten-containing material used as a seed layer or a nucleation layer is deposited. Thereafter, the remaining tungsten-containing material (body layer) is deposited on the nucleation layer. Conventionally, tungsten-containing materials are formed by a reduction reaction of tungsten hexafluoride (WF ₆ ) and hydrogen (H ₂ ). The tungsten-containing material is deposited over the entire exposed surface area of the substrate including several features and a field region.

Depositing tungsten-containing material in small and high aspect ratio features can cause seams and cavities to form within the filled features. Large joints can cause high impedance, contamination of the filled material, loss of the filled material, and in other cases reduce the efficiency of the integrated circuit. For example, the seam may extend close to the field region after the filling process and then open during chemical mechanical planarization.

This article provides methods for depositing tungsten into features of different sizes. An embodiment relates to a method for processing a semiconductor substrate through the following steps: (i) providing a substrate including features having openings of different sizes; (ii) depositing a first body tungsten layer into the features to Partially filling the features; (iii) performing a non-conformal etch of the first body tungsten layer to leave an etched tungsten layer in the features, including removing a phase from the top of the features More tungsten than inside the features; and (iv) depositing a second body tungsten layer on the etched tungsten layer so that the deposition system of the second body tungsten layer is interrupted to When filling smaller features, the etched tungsten layer is processed.

In some embodiments, processing the substrate includes exposing the substrate to a reducing agent. The reducing agent may be selected from the group consisting of borane, silane, and hydrogen. In some embodiments, processing the substrate includes exposing the substrate to nitrogen, annealing the substrate, and / or depositing a barrier layer on the substrate. The barrier layer may be, for example, tungsten nitride.

In various embodiments, the feature has a plurality of openings between about 1 nm and about 1 micron. In some embodiments, the features have openings of about twenty different sizes.

Another embodiment involves processing a semiconductor substrate through the following steps: (i) providing a substrate including a plurality of features having at least one set of smaller features and at least one set of larger features; (ii) deposition A first body tungsten layer in the features; (iii) etching a part of the first body tungsten layer at a first temperature; (iv) depositing a second body tungsten layer on the etched first A tungsten layer to fill the at least one set of smaller features and at least partially fill other features; (v) etching a portion of the second body tungsten layer at a second temperature; and (vi) depositing a third body A tungsten layer is on the etched second tungsten layer to fill one of the at least one group of larger features.

In some embodiments, the first temperature is lower than the second temperature. In some embodiments, the first temperature is higher than the second temperature.

In various embodiments, each of the at least one set of smaller features and the at least one set of larger features includes a plurality of features having at least one feature size. Each of the at least one group of smaller features may include a feature and each of the at least one group of larger features may include a feature. In some embodiments, the at least one set of smaller features includes a plurality of features having an opening between about 1 nm and about 2 nm.

In various embodiments, the plurality of features in the at least one larger set of features have an opening between about 100 nm and about 1 micron. In some embodiments, the key feature of the largest feature in the group with the largest feature has at least five times the key dimension of the largest feature in the group with the smallest feature.

Another embodiment relates to a device for processing a semiconductor substrate. The device includes a processing chamber including a shower head and a substrate holder; and a control having at least a processor and a memory. A processor, so that the at least one processor and the memory are communicably connected to each other, the at least one processor is at least operatively connected to a flow control hardware, and the memory system stores a machine-readable memory for performing the following operations: Fetching instructions: introducing a tungsten-containing precursor and a reducing agent into the chamber; introducing a fluorine-containing etchant into the chamber to etch a portion of the first body tungsten layer to leave an etched tungsten layer in the plurality of features Medium; introducing a tungsten-containing precursor and a reducing agent into the chamber to deposit a second host tungsten layer; temporarily terminating the deposition of the second host tungsten layer at a predetermined time; introducing a processing reagent into the chamber; termination Introducing a processing reagent into the chamber; and continuing to introduce a tungsten-containing precursor and a reducing agent into the chamber to deposit a second bulk tungsten layer.

In some embodiments, the processing reagent is selected from the group consisting of borane, silane, and hydrogen. In some embodiments, the predetermined time is the time when the small features are filled.

These and other implementations are further described below with reference to the drawings.

In the following description, numerous specific details are provided to provide a thorough understanding of the present invention. The invention may be practiced without the part or owner of these specific details. In other cases, well-known process steps and / or structures will not be described in detail to avoid unnecessarily defocusing the present invention. The invention will be described in conjunction with specific embodiments, but I will understand that this is not intended to limit the invention to those embodiments.

This article describes a method of filling features with tungsten and related systems and equipment. Examples of applications include logic and memory contact window filling, DRAM embedded word line filling, vertically integrated memory gate / word line filling, and 3-D integration with through silicon vias (TSVs). The method described herein can be used to fill vertical features, such as those in tungsten vias, and horizontal features, such as vertical NAND (VNAND) word lines. These methods can be used for processing FinFET structures. The feature portion formed in the substrate may have one or more of narrow and / or recessed openings, a shrinkage portion within the feature portion, and a high aspect ratio. The substrate may be a silicon wafer, such as a 200mm wafer, a 300mm wafer, a 450mm wafer, including a wafer having a layer of one or more materials such as a dielectric, conductive, or semiconductive material deposited thereon.

Features may be formed in one or more of these layers. For example, the features may be formed at least partially in a dielectric layer. A single substrate described herein has features of different sizes. In some embodiments, there can be up to 20 features of more than 20 features on a single wafer. The size of the feature hole near the opening, such as the diameter or line width of the opening, may be between about 1 nm and 1 micrometer, such as between about 25 nm and 300 nm. Examples of "small" features include features with opening diameters between about 1 nm and about 2 nm. Examples of "large" features include features with opening diameters on the order of hundreds of nm to about 1 micron. Feature holes may be referred to as unfilled features or directly as features. In some embodiments, the feature holes may have an aspect ratio of at least about 2: 1, at least about 4: 1, at least about 6: 1, or higher.

When filling a single-size feature on a substrate, a tungsten layer is deposited in the feature to partially fill the feature, and then a portion of the deposited tungsten is removed so that the average thickness of the deposited layer near the opening is reduced by more than Due to the reduction in the average thickness of the deposited layer in the features, this can be used to produce void-free feature fills. However, when a wide range of feature sizes are to be filled, this approach may not provide the benefit of the greatest improvement in filling.

This system is shown in FIG. 1, which shows a small critical dimension (CD) feature 102 and a large CD feature 104 on a substrate. These features can be filled by depositing a first body tungsten layer on the features, etching the first body layer, and then depositing a second body layer to fill the rest of the features. This solution can be described as "deposition-etch-deposition" in this article. The first body deposition (eg, the first "deposition" or "deposition 1" of "deposition-etch-deposition") partially fills the small CD feature 102 to obtain a small CD feature partially filled at 120. Since the feature has a recessed profile, that is, a profile that narrows toward the feature opening, there is a pinch-off point on which the deposit can pinch off the feature opening. The first body deposit partially fills the large CD feature 104 to obtain a partially filled large CD feature as shown at 140 as well. Tungsten etching (for example, "etch" of "deposition-etch-deposition") can better remove tungsten near the feature opening of the small CD feature 104, as shown in 122, because the feature opening Because it is small, almost no tungsten is etched on the sidewall of the feature. This reshapes the profile of the feature so that subsequent void-free filling can be performed (eg, a second "deposition" or "deposition 2" of "deposition-etch-deposition") (not shown) and No pinch off. However, due to the large CD feature 104, tungsten is also etched at the top and deep inside the feature. Due to the large opening at the top of the feature 104, there is no benefit in reshaping the contour of the feature, as in 142 As shown.

The change in the tungsten filler throughout the wafer due to the difference in feature size and feature density is called the pattern loading effect. Filling the features in this way results in uneven and rough tungsten growth on a substrate with several feature sizes. The large feature part is mainly filled with the deposition of the second body tungsten, resulting in large and coarse tungsten grains in the large feature part due to the pattern loading effect.

The invention provides a method for filling feature portions of different sizes on a substrate, which has smoother tungsten and reduces pattern loading effect. These methods can be used for feature filling of features in any direction, including vertical and horizontal features. In some embodiments, the methods can be used to fill a fill having features having an angled direction relative to a plane of the substrate. In some embodiments, these methods can be used to fill features with several directions. Examples of such features include 3D features in which the deposition gas can enter a feature vertically and laterally. The method described herein is particularly suitable for FinFET processing, which involves depositing tungsten onto substrates having different feature sizes.

Some embodiments of the method involve interrupting the second body deposition to treat the deposited tungsten surface, and then continuing the second body deposition to regenerate smaller grains on the treated surface, and to smoother The remaining portion of the feature is filled with deposited tungsten. Some embodiments of these methods involve classifying the more feature sizes into smaller and larger feature size groups, and performing the order of the first deposition, etching, and second deposition in a cyclic manner, the goal of each cycle is A feature size group, from smallest to largest, and each etching chemical is selected to etch the feature size group of the target.

Although the following description focuses on the tungsten feature filling, the embodiments of the present invention can also be implemented by filling the features with other materials. For example, feature fill using one or more of the techniques described herein can be used to fill features with other materials, including tungsten-containing materials (eg, tungsten nitride (WN) and tungsten carbide (WC)), titanium-containing materials ( Such as titanium (Ti), titanium nitride (TiN), titanium silicide (TiSi), titanium carbide (TiC), and titanium aluminum alloy (TiAl)), tantalum-containing materials (for example, tantalum (Ta) and tantalum nitride (TaN )), And nickel-containing materials (for example, nickel (Ni) and nickel silicide (NiSi).

FIG. 2 is a process flowchart showing some operations of a method of filling a feature by depositing a first body of tungsten, etching the first body of tungsten, and depositing a second body of tungsten. The method may begin by depositing tungsten in a feature in operation 211 to partially fill the feature. In some embodiments, the tungsten system is deposited conformally. In some embodiments, operation 211 may involve the deposition of a tungsten nucleation layer, followed by the deposition of the bulk. Tungsten nucleation layer deposition and bulk deposition techniques are further described below. In some embodiments, the deposition of the tungsten nucleation layer is performed by sequentially pulsed tungsten-containing precursor and one or more reducing agents through atomic layer deposition (ALD) or pulsed nucleation layer (PNL) processing to form tungsten formation. The nuclear layer does it. In some embodiments, operation 211 may involve body-only deposition if, for example, the feature includes an underlying layer supporting a tungsten deposit. Bulk deposition can be deposited by chemical vapor deposition and is further described below.

In a feature including a constriction or otherwise susceptible to pinching, operation 211 may be performed at least until the feature is pinched. Features with different sizes may be pinched off at different times. In conformal deposition, the deposition starts from each surface and progresses with growth generally perpendicular to the surface. The tungsten growth in the feature starts from each side wall and progresses until the growth pinches the feature. In some embodiments, the amount of tungsten deposited in operation 211 may be determined based on the narrowest feature size. For example, if the narrowest size is 50 nm, the CVD reaction in operation 211 can be performed for a period of time sufficient to deposit 25 nm on various surfaces, at which point further tungsten reactants are prevented from diffusing into the features by the deposited tungsten. This can be roughly determined based on the dynamic properties of the reaction, the thickness of the tungsten nucleation layer, and the like before the reaction. In some embodiments, operation 211 may involve several deposition-etch-deposition cycles for a single feature, as described in US Pat. No. 8,124,531, which is incorporated herein by reference. In some embodiments, operation 211 does not include any etching operation, and only needs to be deposited until at least the feature is pinched off. Operation 211 may occur in a single chamber, multiple stations or a single station in a single station chamber, multiple stations in a multiple station device, or in multiple chambers. For example, operation 211 may include deposition of a tungsten nucleation layer in one station of the chamber, followed by deposition of a body in another station of the chamber. During operation 211, many small features may be almost filled, while large features may only have a thinner layer of tungsten deposited.

The process may continue at a local etch of tungsten in operation 213. Some tungsten remains in the feature, but the etching removes tungsten from at least a portion of the sidewall of the feature. Etching in a smaller feature may etch only the top of a feature near the surface of the substrate, while etching in a larger feature may cause etchant species to penetrate into the feature and etch even the sidewall of the feature . Operation 213 typically involves chemical etching, which is performed, for example, with a fluorine-containing species or other etchant species. In some embodiments, activated species can be used. Activated species may include atomic species, free radical species, and ionic species. For the purposes of this application, an activated species is different from a recombinant species, and different from the gas originally fed into the plasma generator. For example, partially etching the deposited tungsten may involve exposure to etchant species generated in a remote or in-situ plasma generator. In some embodiments, both remotely generated and in situ generated plasma species can be used sequentially or simultaneously. In some embodiments, non-plasma chemical etching using F ₂ , CF ₃ Cl, or other etchant chemicals may be used. Operation 213 may occur in the same chamber as in operation 210 or in a different chamber. The method of etching tungsten in a feature is further described below. According to the feature structure, the etching may be conformal or non-conformal. Etching conformality is further described below. Etching can be performed generally laterally (perpendicular to the feature axis) and / or vertically (along the feature axis).

According to various embodiments, the etching may take precedence over or not over an underlying layer. For example, the etch may be prioritized to W while, for example, the underlying layer of Ti or TiN is terminated as an etch. In some embodiments, the etch can etch W and have Ti or TiN with a dielectric below it as an etch stop.

In this system, the removal rate within a feature is affected by the amount and / or relative composition of different etch material components that diffuse into the feature (eg, initial etchant material, activated etchant species, and recombined etch Agent species). In some embodiments, the etch rate depends on the concentration of various etchant components at different locations within the feature. I should note that the terms "etched" and "removed" are used interchangeably in this article. I should understand that any removal technique, including etching and other techniques, can be used for selective removal.

Then, the process continues to deposit the remaining tungsten at operation 215, so that a second body of tungsten is deposited in the features. Subsequent tungsten deposition re-grows tungsten in the vias on the existing tungsten layer, and the significant growth delay in the field prevents pinch-off and cavities during final filling. As noted above, significant growth delay may be due, at least in part, to the removal of the surface that supports tungsten growth. In some embodiments, the second host tungsten deposition may be performed by simultaneously introducing a tungsten-containing precursor and a reducing agent to deposit another host layer by CVD. In some embodiments, the deposition process can deposit a small amount of tungsten on the sidewall surface, although at a slower growth rate than the tungsten surface. For example, the growth rate and deposition thickness on the sidewall surface may be half or less of those on the tungsten surface. In some embodiments, it may be one tenth or one hundredth. In some embodiments, tungsten may be deposited on all surfaces of the features at the same growth rate in the deposition process.

In some embodiments, operation 215 may continue without depositing a nucleation layer. This may allow deposition on only the remaining tungsten in the feature. In many embodiments, operation 211 will involve depositing a nucleation layer to achieve conformal deposition, while operation 215 continues the deposition on the etched tungsten layer without the deposition of an intermediate nucleation layer. In some embodiments, a nucleation layer may be deposited on at least the portion of a feature on which further growth is desired. If the nucleation layer in operation 215 is deposited on a sidewall or other surface including subsequent undesired depositions, tungsten nucleation on such surfaces may be selectively suppressed. A method for inhibiting tungsten nucleation in a feature is described in US Patent Application No. 13/774350, which is incorporated herein by reference. Further description of the deposition-etch-deposition scheme is described in US Patent Application No. 13/851885, which is incorporated herein by reference.

In some embodiments, the methods include one or more deposition operations that involve initiating a "rate-limited" system by reducing the reaction rate from the conversion of the tungsten precursor to the deposited tungsten. This can be done by increasing the partial pressure of the tungsten precursor during the second body tungsten deposition process, such as during operation 215 described above with respect to FIG. 2.

In a rate-limited system, the deposition rate is limited by the amount of tungsten-containing precursors, such as tungsten hexafluoride (WF ₆ ), supplied to the substrate. In some examples, the deposition rate on the features may depend on the partial pressure of the tungsten-containing precursor. This can be achieved by increasing the partial pressure of the tungsten-containing precursor in the processing chamber (eg, using a low flow rate) while maintaining a high reaction rate (eg, low temperature).

Part of the rate-limiting condition is a change in overall tungsten-containing precursor concentration, processing temperature, or processing pressure. In some embodiments, the concentration of the tungsten-containing precursor in the smaller features is lower than in the larger features. The deposition in features of different sizes depends on the feature density of the substrate. For example, in any given area of the surface of the substrate, if there are many smaller features in that area, more tungsten must be deposited on the surfaces of those features in that area because the sidewalls and bottom surfaces of the features The total surface area is greater than the area of a substrate of the same size with one or two large features. This in turn leads to pattern loading effects, especially in smaller features.

When depositing tungsten in a rate-constrained system, tungsten can be deposited more uniformly throughout the smaller features because the load effect is greater in the smaller features than in the larger features. Rate-limited processing conditions can be achieved by supplying a predetermined amount of tungsten-containing precursor into the processing chamber (eg, using a low tungsten-containing precursor flow rate relative to the cavity profile and size) to deposit tungsten on larger features Group or smaller size feature group.

The method of selecting a predetermined temperature or pressure during the deposition can not only cause tungsten to be deposited on the surface of the feature, but also control the reaction rate. Overall, the substrate temperature can be based on the chemical composition, the desired deposition rate, the desired concentration distribution of the tungsten-containing precursor, and other materials and processing parameters. Interrupted deposition scheme

The interrupted deposition scheme can be used to deposit tungsten, so that the second main body tungsten deposition processing system is suspended at a predetermined stage. Implementing this method can fill more challenging small CD features while allowing simpler and larger CD features to be subsequently filled. For example, a process may involve: □ Deposition 1 (targeting small CD features) □ Selective etching □ Short etch 2 (complete filling of smaller CD features, leaving larger CD features open) □ Process (eg B ₂ H ₆ 、 SiH ₄ soak) □ Continue to deposit 2

FIG. 3 is a process flow diagram showing a method for depositing tungsten in features of different sizes on a substrate according to a disclosed embodiment. In operation 310, a tungsten system is deposited in a feature of a substrate having features of different sizes. Tungsten may be deposited using any technique relative to operation 211 in FIG. 2. For example, in various embodiments, the tungsten nucleation layer is deposited, followed by the deposition of a first bulk tungsten layer.

In operation 312, the deposited tungsten system is partially etched. The conditions and methods may be any of those described above with respect to operation 213 in FIG. 2. Etching conditions are discussed further below. The smaller features can be etched, so that only the top portion of the features near the surface of the substrate is etched, and the etching stops at the pinch-off position of the features due to the high aspect ratio and narrow opening. However, for larger features, the etch can enter the features and also etch the sidewalls with a conformal etch.

In operation 314, the tungsten system is deposited into the features in the second bulk tungsten deposition, but the deposition is interrupted at a predetermined time. The predetermined time may be the time when the small features on the substrate are completely filled with tungsten. At a predetermined time, the second bulk tungsten deposition system is temporarily terminated.

As shown in the figure, operation 314 may include first depositing the remaining tungsten on the substrate in operation 314a by focusing on filling the small features completely, and then in operation 314b when the small features are transmitted through. When the surface of the substrate is filled, the deposition is interrupted and the remaining tungsten is deposited to fill the large features in operation 314c. Interrupting the tungsten bulk deposition may enhance filling in larger features by one or more mechanisms. In some embodiments, the previous etch operation may have an occasional passivation effect, which results in a delayed nucleation of filling in large features. For example, exposure to a nitrogen-containing etchant may passivate a portion of the deposited surface. This process removes passivation and reduces nucleation delay. In some embodiments, the operation of processing larger features results in smoother grains in the larger features.

In various embodiments, operations 314a through 314c are performed in the same chamber, and flow is between operations 314a and 314b, and turns and / or changes between operations 314b and 314c. In some embodiments, operation 314 is interrupted once. In some embodiments, operation 314 is interrupted twice, three times, or more, causing operations 314a to 314c to repeat until the features are all filled.

The substrate may be processed in operation 314b through various methods. In some embodiments, the substrate is treated by soaking with a reducing agent, which can expose the surface of the substrate, and thus, the deposited tungsten is treated with the reducing agent. Examples of the reducing agent include borane (for example, B ₂ H ₆ ), silane (for example, SiH ₄ ), and hydrogen (H ₂ ). The substrate may be processed by a reducing agent for about 2 seconds to about 10 seconds. This treatment may be hot soaking and may occur at a temperature from about 200 ° C to about 500 ° C. According to various embodiments, the partial pressure of H ₂ or other reducing agent may be at least about 15 Torr, at least about 20 Torr, at least about 30 Torr, at least about 40 Torr, at least about 50 Torr, at least about 60 Torr, at least about 70 Torr , Or at least about 80 Torr.

In some embodiments, once the bulk deposition continues, the reducing agent soak reduces the roughness of the deposited tungsten. In one example, operation 314 may involve exposing the substrate to the flow of tungsten-containing precursor and reducing agent (314a), stopping or diverting the flow of tungsten-containing precursor to a period of time such that the reducing agent or processing chemical Flow in the case of a tungsten precursor (314b), terminate the flow of the processing chemical, and continue the flow of the tungsten-containing precursor to continue interrupted bulk deposition (314c). In alternative embodiments, operation 314b may involve exposing the substrate to a different reducing agent (such as diborane or silane) to add or replace the reducing agent used in the bulk deposition.

Processing operations 314b may include exposing the substrate to a nitrogen (N ₂₎ or a continuous pulse of nitrogen gas (N ₂₎ gas. The pulse of exposing the substrate to nitrogen helps reduce grain roughness. Some discussions of the pulses of exposing a substrate to nitrogen are described in US Patent No. 8551885 and US Patent Application No. 13/633798, which are incorporated herein by reference. In some embodiments, the processing in operation 314b includes annealing the substrate, such as a temperature between about 200 ° C and about 600 ° C. Annealing the substrate reduces the roughness and provides a smooth surface to allow tungsten grains to grow on it in subsequent processing steps. In some embodiments, the processing in operation 314b includes: depositing a barrier layer, such as a fluorine-free WN layer, on the substrate. The barrier layer may be between about 10 Å and 500 Å thick, or, in more specific embodiments, between about 25 Å and 200 Å thick. The barrier layer can be deposited by atomic layer deposition (ALD). The barrier layer can provide a new surface for subsequent tungsten grains to be deposited thereon, thereby forming smaller tungsten grains in the features.

In some embodiments, the process in operation 314b includes flowing a fluorine-free tungsten precursor into the chamber. Examples of fluorine-free tungsten precursors include tungsten hexachloride (WCl ₆ ), MDNOW (methylcyclopentadiene-dicarbonylnitrosamidine-tungsten), and EDNOW (ethylcyclopentadiene-dicarbonylnitrosammonium) -Tungsten). In some embodiments, these combinations may be performed during processing. For example, processing may include first depositing fluorine-free tungsten nitride and annealing the substrate, and converting the fluorine-free tungsten nitride into fluorine-free tungsten in the feature. Several deposition-etch-deposition schemes

Several deposition-etch-deposition cycles can be used to fill features of different sizes with tungsten, and each cycle is set to fill a set of features of similar size. An example of a cycle is described above with respect to FIG. 2. Repeated cycles make the second deposition of the previous cycle coincide with the first deposition of the next cycle. For example, the sequence of "deposition-etch-deposition-etch-deposition-etch-deposition" includes a total of three cycles.

A set of features may include one, two, three, four, five, or more different features having the same or similar dimensions. For example, a set of features may include three features each having an opening between 11 nm and 2 nm. The total number of features on the wafer can be divided into arrays, so that one group includes the smallest feature, the next group includes the next smallest feature, and so on, until the last group includes the largest feature. Each group can be adjusted in each deposition-etch-deposition cycle from the group with the smallest feature to the group with the largest feature. For example, in the first deposition-etch-deposition cycle, the group with the smallest feature is targeted, and in the following deposition-etch-deposition cycle, the group with the second smallest feature is The target, and so on, until the last deposition-etch-deposition cycle, the group with the largest feature is targeted.

The term "target" can be used to describe the etching chemicals and processing conditions used in each corresponding cycle. For example, a first deposition-etch-deposition cycle targeted at a group having the smallest features may include an etching process specifically for etching the smallest features. This may include shorter time exposure to the etchant, lower etchant flow rate, or other adjustments in the etching operation. The technology described in US Patent Application No. 13/851885, fully incorporated herein by reference, can be used to populate any particular set of features in accordance with the disclosed embodiments.

During each cycle, the second deposit in any one cycle completely fills the smaller feature of the target in that cycle, but the second deposit terminates before the larger feature is pinched off. In the next cycle, the target is a larger feature, so that during the second deposition of the corresponding cycle, these larger features are completely filled, but the deposition is terminated before the next larger feature is pinched off. The smaller CD features are filled during the second deposition operation, but the operation is terminated before the features of the larger CD are pinched off. Then another selective etch is performed with the goal of improving the filling in the larger CD features, followed by a third deposition of bulk tungsten. Since the small CD features are already filled, these features are not affected. For example, a process may involve: l Deposition 1 (targeting (plural) small CD features) l Selective etching l Short-term deposition 2 (to completely fill (plural) small CD features to make large CD features Open) l Selective etching (non-conformal etching in (plural) large CD features, (plural) small CD features remain filled and unaffected) l Deposit 3 (filled (plural) large CD features )

By performing several deposition-etch-deposition cycles, the smaller features are filled first and the largest features are filled last. In this scheme, when etching operations are performed in subsequent processing cycles, the smaller features are not affected because they are already completely filled by their respective deposition-etch-deposition cycles. Therefore, all the feature parts on the substrate, regardless of their size, are finally filled with a cavity-free, high-quality tungsten film.

FIG. 4 is a process flow diagram depicting an example of the operation of the method to implement the disclosed embodiment. In operation 401, the tungsten system is deposited by targeting the smallest feature of the first group. I should understand that when the smallest feature of the first group is targeted, other features may also have tungsten deposited in it. The conditions and methods of deposition may be any of those described above with respect to operation 211 of FIG. 2. For example, the substrate may be exposed to WF ₆ and H ₂ to deposit tungsten by chemical vapor deposition. In some embodiments, a tungsten nucleation layer is deposited and then a first body layer of tungsten is deposited.

In operation 403, the first host tungsten system deposited in the feature is partially etched. The etching conditions may be set for a feature having a specific size among a group of the smallest features. For example, if the features in the first group with openings between about 1 nm and about 2 nm are targeted, the etching conditions can be selected to allow the tungsten on the top of these features to be etched just enough to open This feature is used for subsequent deposition. In general, the etching conditions may be any of those described above with respect to operation 213 in FIG. 2. The etching process is further described below.

In operation 405, a tungsten system is deposited in the features. The deposition conditions and techniques may be any of those described above with reference to FIG. 2 in operation 213. During this operation, tungsten completely fills the target or selected set of features, and is partially deposited in a second or next target set with the next smallest feature size. The deposition conditions, such as deposition rate, temperature, and pressure of the tungsten-containing precursor, can be rate-limited, so that the reaction rate depends on the deposition of tungsten in the smaller features. As discussed above, the rate-limited system helps reduce pattern loading effects on substrates with many small features, because tungsten deposited on a larger surface area of smaller features in a given area of a substrate More than tungsten deposited on the surface area of a larger feature in the same size area of the substrate. Operation 405 may be terminated before the features of the next set of targets are pinched.

In operation 407, the deposited tungsten system is partially etched, so that the condition system used is adjusted to partially etch tungsten in the feature portion of the second set of targets. Since each etching system is specifically adjusted to etch each set of features, the etching chemicals and conditions in operation 407 may be different from those in operation 403. In some embodiments, more (or less, depending on the feature) non-conformal etch is used in operation 407 to prevent deep etching in large CD features. For example, operation 407 may be performed to make the temperature lower than the temperature in operation 403. In some embodiments, operation 407 may be performed such that the temperature is greater than the temperature during operation 403.

An embodiment of non-conformal etching is described in U.S. Patent No. 8,435,894, which is incorporated herein by reference, in which a through-hole is partially filled with tungsten, and then tungsten is mainly etched with fluorine, followed by phase etching. Tungsten near the opening is etched more deeply than into the feature. After that, tungsten can be deposited to fill the features. (I should note that the non-conformal etch in U.S. Patent No. 8,435,894 is referred to elsewhere as "selective removal," because more material is removed at certain locations in a feature than Material removed elsewhere in the feature. Selective removal in this context is different from selective etching of one material and not the other.) Non-guaranteed in the context of the disclosed embodiments Shaped etching refers to etching with preferential or low step coverage. To obtain preferential (or low step coverage) etching, the processing conditions for the etching are carefully designed. A combination of appropriate etch temperature, etchant flow, and etch pressure can help achieve the desired shape retention. If the etch conformality is not adjusted to suit each type of recessed structure, this can still cause suboptimal filling even after the deposition-etch-deposition sequence.

The step coverage is proportional to (reactant species available for reaction) / (reaction rate). In some embodiments disclosed herein, where the main etchant is the etching of the feature of atomic fluorine, this can be simplified as: W step coverage (Atomic F concentration) / Etching rate

Therefore, in order to achieve a certain tungsten etching step coverage (or desired etch conformal or etch non-conformal), the flow rate of NF ₃ (or the flow rate of other F-containing etchant) and the etch temperature are the key parameters Because they directly affect the atomic fluorine concentration and etch rate. Such as etching pressure and carrier gas flow are also very important.

At higher temperatures, the inflowing fluorine atoms quickly react and etch at the entrance of the feature, resulting in more non-conformal etching; at lower temperatures, the influent fluorine atoms can diffuse and etch deeper into the feature , Resulting in a more conformal etch. Higher etchant flow rates will generate more fluorine atoms, allowing more fluorine atoms to diffuse and etch deeper into the features, resulting in a more conformal etch. A lower etchant flow rate will generate fewer fluorine atoms, which will react and etch at the entrance of the feature, resulting in a less conformal etch. Higher pressures cause more recombination of fluorine radicals to form fluorine molecules. Fluorine molecules have a lower adhesion coefficient than fluorine radicals and are therefore more likely to diffuse into features before etching tungsten, resulting in a more conformal etch.

FIG. 5 shows a schematic cross-sectional view of a part of the features 501 and 502 with different contours deposited and etched. The feature portion 501 includes a constriction portion 551 below the middle thereof; and the feature portion 502 includes a protruding portion 515 near the opening of the feature portion. Standard CVD-W will cause cavities in this feature due to pinch-off caused by the constricted portion 551 and the protruding portion 515, respectively. The etching of the feature 501 is a more conformal etch at a lower temperature and / or more etchant species (fluorine radicals (F *) in this embodiment) to further diffuse the etchant species into the Features. The etching of the feature 502 is a non-conformal etching at a higher temperature and / or a lower etchant concentration.

FIG. 6 is a graph showing the etch rate of different NF ₃ flows as a function of etch temperature. Etching conformality can be increased by designing a process with a low etch rate with a high NF ₃ flow rate. In one example, the area labeled "High Selectivity and High Conformal Etching" indicates several processing conditions under which the etching system is selective (W is better than Ti or TiN) and throughout the feature system It is highly conformal. Although the lowest etch temperature and the highest NF ₃ flow rate tested were 25 ° C and 100 sccm, respectively, higher shape retention can be achieved. This is achieved by reducing the etch temperature and increasing the NF ₃ flow rate (more atomic F radicals). ) To achieve a system with a limited reaction rate. Conversely, by operating in a mass transfer restriction system, the non-conformity of etching can be increased. In this mass transfer restriction system, a high etch rate is achieved with low NF ₃ flow (less atomic F radicals). Reference, for example, the area labeled "Lightly Selective and Highly Non-Conformal Etching".

In some embodiments, conformal etching may include one or more of the following processing conditions: a temperature below about 25 ° C, an etchant flow rate above about 50 sccm, and a pressure greater than about 0.5 Torr. In some embodiments, the non-conformal etch may include one of the following processing conditions: a temperature above about 25 ° C, an etchant flow below about 50 sccm, and a pressure greater than about 2 Torr. Desired step coverage (eg, 60% step coverage) may involve adjusting one or more of these processing conditions to make the process more conformal or non-conformal.

Returning to FIG. 4 again, in operation 409, the tungsten system is deposited on the features, so that the features of the second group are completely filled and the features of the third group having the second largest feature size are partially filled. . The deposition conditions, such as deposition rate, temperature, and pressure of the tungsten-containing precursor, may be rate-limited as described above. Operation 409 was terminated before the next, or the third set of features were pinched off. In operation 411, tungsten is etched using an etch chemistry for the third group of etch. I should note that the etching chemicals will not affect the first or second set of features, because these smaller features are completely filled. The etching chemical may etch some tungsten on the surface of the feature or near the top of the feature, but the etching chemical is not sufficient to generate any voids in the smaller features, and subsequent deposition of tungsten will continue to these The deposition on the surface allows a smooth tungsten filler with no voids. These deposition-etch-deposition cycles can be repeated, so that each set of features is sequentially filled from the set with the smallest feature to the set with the largest feature.

As shown in FIG. 4, in operation 413, finally tungsten is deposited into the group of the second largest feature to completely fill the features while partially filling tungsten into the largest group of features. In operation 415, etching of tungsten is performed under conditions for tungsten etched on the group of the second largest feature. Finally, in operation 417, the remaining largest features are filled with tungsten.

Figures 7 and 8 show examples of a small CD feature (Figure 7) and a large CD feature (Figure 8) on a single substrate in two cycles of several deposition-etch-deposition sequences. As shown, operations 401 in FIG. 7 and operations 401 in FIG. 4 are shown in FIG. 7 and 801 in FIG. 8. The tungsten system is deposited in small CD features and large features, and these features all show conformal growth on their surfaces. In operation 403 of FIG. 4, the small feature portions etched in operation 703 of FIG. 7 are used to etch the deposited tungsten, and the tungsten deposited in the large feature portions in operation 803 of FIG. 8 is also etched. I should note that the etchant species can enter the large features in operation 803 and etch away substantially more sidewalls than the small features etched by the etchant species in 703. In operation 405 of FIG. 4, a tungsten system is deposited in the features to fill the smallest features, as shown in FIG. 705. At the same time, tungsten was also deposited in the large features, as shown in Figure 805, but I should note that the deposition was terminated before the larger features were pinched off. In operation 407 of FIG. 4, the larger features are etched with an etching chemical for the larger features, as shown in FIG. 807. Although it involves etching chemicals, the etchant does not affect the filled tungsten in the smaller features in Figure 707, so there is less need to worry about gaps or cavities appearing in the smaller features. In operation 409 of FIG. 4, the tungsten system is deposited to fill the larger features, as shown in FIG. 809. At the same time, the smaller feature system as shown in Figure 709 is not affected-the additional tungsten system is deposited only on the surface of the substrate. In the examples of FIGS. 7 and 8, only two feature sizes are depicted to show one possible example of several deposition-etch-deposition cycles. I should understand that substrates can have features with multiple sizes, such as 20 or more feature sizes, and etching chemicals can be targeted for features that are grouped by size, and that different groups can include one feature size, Or two feature sizes, or more feature sizes, for example, five feature sizes in a group. For example, the largest CD of a large feature in a group with larger features may be 1.5 times or 2 times the largest CD of a small feature in a group with smaller features. , Or 5 times, or 10 times, or more than 10 times. Nucleation layer deposition

In some embodiments, the methods described herein involve depositing a tungsten nucleation layer before depositing a bulk layer. The nucleation layer is usually a thin conformal layer, which can promote subsequent deposition of a bulk tungsten-containing material thereon. According to various embodiments, the deposition of the nucleation layer may be performed before any filling of the feature and / or at a later point in time during the filling of the feature. For example, in some embodiments, a nucleation layer may be deposited after etching tungsten in the features.

In some embodiments, a nucleation layer is deposited using pulsed nucleation layer (PNL) technology. In the PNL technology, pulses of a reducing agent, a flushing gas, and a tungsten-containing precursor can be sequentially injected into and flushed from the reaction chamber. This process is repeated in a cyclic manner until the desired thickness is reached. PNL broadly embodies any cyclic process, including atomic layer deposition (ALD) technology, that sequentially adds reactants to generate a reaction on a semiconductor substrate. PNL technology for depositing a tungsten nucleation layer is described in U.S. Pat. All are incorporated herein by reference. The thickness of the nucleation layer may depend on the nucleation layer deposition method and the desired quality of the host deposition. In general, the thickness of the nucleation layer is sufficient to support high-quality, uniform bulk deposition. An example might be about 10Å-100Å.

Although examples of PNL deposition are provided above, the methods described herein are not limited to specific methods for the deposition of tungsten nucleation layers, but include the deposition of bulk tungsten films by any method, including PNL, ALD, CVD, and physical gas. Phase deposition (PVD) on the tungsten nucleation layer. In addition, in some embodiments, bulk tungsten can be deposited directly into the features without the use of a nucleation layer. For example, in some embodiments, the feature surface and / or the underlying substrate that has been deposited supports the bulk tungsten deposition. In some embodiments, a bulk tungsten deposition process that does not use a nucleation layer may be performed. For example, US Patent Application No. 13/560688 filed on July 27, 2012, which is incorporated herein by reference, describes the deposition of a bulk tungsten layer without the use of a nucleation layer.

In various implementations, the deposition of a tungsten nucleation layer may involve exposure to a tungsten-containing precursor, such as tungsten hexafluoride (WF ₆ ), tungsten hexachloride (WCl ₆ ), and tungsten hexacarbonyl (W (CO) ₆ ) . In some embodiments, the tungsten-containing precursor is a halogen-containing compound, such as WF ₆ . Organometallic precursors and fluorine-free precursors can also be used, such as MDNOW (methylcyclopentadiene-dicarbonyl nitrosamidine-tungsten) and EDNOW (ethylcyclopentadiene-dicarbonyl nitrosammonium-tungsten) .

Examples of the reducing agent may include a boron-containing reducing agent including diborane (B ₂ H ₆ ) and other boranes; a silicon-containing reducing agent including silane (SiH ₄ ) and other silanes, hydrazine, and germane. In some embodiments, the pulse of the tungsten-containing precursor may be alternated with the pulse of one or more reducing agents. Examples of the reducing agent are S / W / S / W / B / W, etc., where W represents a tungsten-containing precursor Body, S represents a silicon-containing precursor, and B represents a boron-containing precursor. In some embodiments, a separate reducing agent may not be used, for example, tungsten-containing precursors may undergo thermal or plasma-assisted decomposition.

According to various embodiments, hydrogen may or may not flow in the background. In addition, in some embodiments, the deposition of the tungsten nucleation layer may be followed by one more processing operation, followed by the deposition of the bulk tungsten. One method of processing a deposited tungsten nucleation layer to reduce resistivity is described in, for example, U.S. Patent Nos. 7,772,114, 8058170, and 8,623,733, which are incorporated herein by reference. Bulk deposition

In many embodiments, the bulk tungsten deposition may be produced by a CVD process. In the CVD process, a reducing agent and a tungsten-containing precursor system flow into a deposition chamber to deposit a bulk filler layer in a feature. An inert carrier gas may be used to convey one or more of the reactant streams, and the streams of these reactants may or may not be pre-mixed. Unlike PNL or ALD processes, this operation typically involves continuously flowing the reactants until the desired amount has been deposited. In some embodiments, the CVD operation can occur in several stages, and the periods of continuous and simultaneous flow of reactants are separated by periods during which one or more of the shunted reactants flow.

Various tungsten-containing gases including, but not limited to, WF ₆ , WCl ₆ , and W (CO) ₆ can be used as the tungsten-containing precursor. In certain embodiments, the tungsten-containing precursor is a halogen-containing compound, such as WF ₆ . In some embodiments, the reducing agent is hydrogen, but other reducing agents may also be used, including silane (SiH ₄ ), disilane (Si ₂ H ₆ ), hydrazine (N ₂ H ₄ ), diborane ( B ₂ H ₆ ), and germane (GeH ₄ ). In many embodiments, hydrogen is used as a reducing agent in a CVD process. In some other embodiments, the tungsten precursor can be a tungsten precursor that can be decomposed to form a bulk tungsten layer. Bulk deposition can also be produced using other types of processing, including ALD processing.

Examples of temperatures may range from about 200 ° C to about 500 ° C. According to various embodiments, any of the CVD W operations described herein may be filled with low temperature CVD W, for example, at about 250 ° C to 350 ° C or about 300 ° C.

According to various embodiments, deposition may be performed until a certain feature profile is reached and / or a specific amount of tungsten has been deposited. In some embodiments, the deposition time and other related parameters can be determined by simulation and / or trial and error. For example, for an initial deposition of tungsten that can be conformally deposited in a feature until it is pinched, the filling process can be judged directly based on the size of the feature, which can reach the pinch situation. Thickness and corresponding deposition time. In some embodiments, the processing chamber may be equipped with various sensors for performing in-situ measurements for endpoint detection of deposition operations. Examples of in-situ measurements include optical microscopy and X-Ray Fluorescence (XRF) to determine the thickness of the deposited film.

I should understand that the tungsten film described herein may include certain amounts of other compounds, dopants, and / or impurities, such as nitrogen, carbon, oxygen, boron, phosphorus, Sulfur, silicon, germanium, and the like. The tungsten content in the film may range from about 20% to about 100% (atomic) tungsten. In many embodiments, the film is rich in tungsten, with at least about 50% (atomic) tungsten, or even at least about 60%, 75%, 90%, or 99% (atomic) tungsten. In some embodiments, the films may be a mixture of metal or elemental tungsten (W) and other tungsten-containing compounds such as tungsten carbide (WC) and tungsten nitride (WN).

CVD and ALD deposition of these materials may include the use of any suitable precursor. For example, CVD and ALD deposition of tungsten nitride can include the use of halogen- and halogen-free tungsten-containing and nitrogen-containing compounds, as described further below. CVD and ALD deposition of titanium-containing layers may include the use of titanium-containing precursors, examples of which include titanium (dimethylamino) titanium (TDMAT) and titanium chloride (TiCl ₄ ), and if appropriate, one or more Co-reactant. CVD and ALD deposition of tantalum-containing layers may include the use of precursors such as penta (dimethylamine) tantalum (PDMAT) and TaF ₅ and, if appropriate, one or more co-reactants. CVD and ALD deposition of cobalt-containing layers may include the use of precursors, such as cobalt tris (2,2,6,6-tetramethyl-3,5-heptanedione acid), bis (cyclopentadiene) cobalt, And dicobalt hexacarbonyl butylacetylene, and one or more co-reactants. CVD and ALD deposition of nickel-containing layers may include the use of precursors such as cyclopentadienylallylnickel (CpAllylNi) and MeCp ₂ Ni. Examples of co-reactants may include N ₂ , NH ₃ , N ₂ H ₄ , N ₂ H ₆ , SiH ₄ , Si ₃ H ₆ , B ₂ H ₆ , H ₂ , and AlCl ₃ . Tungsten etching

Etching of tungsten can be performed by exposing tungsten to one or more etchant species capable of reacting with tungsten. Examples of etchant species include halogen species and halogen-containing species. Examples of initial etchant materials that can be used to remove tungsten-containing materials include nitrogen trifluoride (NF ₃ ), tetrafluoromethane (CF ₄ ), tetrafluoroethylene (C ₂ F ₄ ), and hexafluoroethane (C ₂ F ₆ ), and octafluoropropane (C ₃ F ₈ ), trifluoromethane (CHF ₃ ), trifluorochloromethane (CF ₃ Cl), sulfur hexafluoride (SF ₆ ), and molecular fluorine (F ₂ ) . In some embodiments, the species can be activated and include free radicals and / or ions. For example, an initial etchant material may flow through a remote plasma generator and / or undergo in-situ plasma processing. In some embodiments, tungsten can be exposed to a non-plasma etchant vapor.

In addition to the examples presented above, known etchant chemicals can be used to etch tungsten-free films and tungsten-containing films. For example, fluorine-containing compounds such as NF ₃ can be used for titanium-containing compounds such as TiN and TiC. Chlorine-containing compounds such as Cl ₂ and BCl ₂ can be used in some embodiments, such as to etch TiAl, TiAlN, nickel-containing compounds, and cobalt-containing compounds. In addition, although the following etching mainly refers to plasma and / or non-plasma vapor phase etching, in some embodiments, wet etching techniques can also be used to implement these methods.

In some embodiments, a remotely generated plasma can be used. The initial etchant material and, in some embodiments, an inert gas, such as argon, helium, etc., can be supplied to any suitable remote plasma generator. Remote plasma units can be used, such as ASTRON® i Type AX7670, ASTRON® e Type AX7680, ASTRON® ex Type AX7685, ASTRON® hf-s Type AX7645 produced by MKS Instruments in Andover, Massachusetts. The remote plasma unit is usually a self-contained device that uses a supplied etchant to generate a weak free plasma. In some embodiments, a high power radio frequency (RF) generator provides energy to the electrons in the plasma. This energy system is then transferred to neutral etchant molecules, causing a thermal decomposition of these molecules at temperatures of the order of 2000K. Due to the high RF energy of the remote plasma unit and the special channel geometry, it can dissociate more than 60% of the input etchant molecules, causing the etchant to absorb most of its energy.

In some embodiments, the active species from the chamber into which the remote plasma unit is transmitted for etching is a free radical and does not substantially contain ionic species. Those of ordinary skill in the art will understand that there may be some small number of ionic species that do not contribute to etching. This number can be small enough to not be detected. In some embodiments, the active species from the chamber into which the remote plasma unit is delivered for etching may include a significant amount of ionic species as well as free radical species.

In some embodiments, the etching operation may use a plasma generated in situ in a chamber in which the substrate is placed, exposing the tungsten system to a direct plasma, as an addition or replacement of the plasma generated remotely. In some embodiments, a radio frequency (RF) plasma generator can be used to generate a plasma between two electrodes in a chamber. Examples of electrodes include, for example, sprinklers and supports. In an example, a high frequency (HF) generator capable of providing between about 0 W and 10000 W at a frequency between about 1 MHz and 100 MHz may be used. In a more specific embodiment, the high-frequency generator can transmit 0 W to 5000 W at about 13.56 MHz. In some embodiments, the low frequency (LF) generator may be between about 100 kHz and 2 MHz, or between about 100 kHz and 1 MHz, for example, a frequency of 400 kHz may be used to provide between about 0 and 10000 W.

The plasma generator can be a capacitively coupled plasma (CCP) generator, an inductively coupled plasma (ICP) generator, a transformer coupled plasma (TCP) generator, an electronic cyclotron resonance (ECR) generator, or a spiral plasma generator. . In addition to RF sources, microwave sources can also be used.

According to various embodiments, some or all of the etching operations may be performed in the same chamber, and other operations including deposition and / or processing operations are also performed in the chamber, or in a dedicated etching chamber. If a dedicated etching chamber is used, the chamber may be connected to the same vacuum environment of one or more other processing chambers, or may be part of a separate vacuum environment. For example, in some embodiments, a TCP etch module can be used, such as a Kiyo® conductor etch module from Lam Research, Fremont, California. Examples of etchants that can be used with this module include NF ₃ , CF ₄ , SF ₆ , CH ₃ F, CH ₂ F ₂ and CF ₄ . Examples of operating pressures may range from about 30 mTorr to about 100 mTorr. An example of temperature may be in a range from about 30 ° C to about 120 ° C.

In various embodiments, the etching is performed until certain characteristics of the deposited tungsten are removed or a certain profile is reached. For example, etching may continue until the clamped off tungsten is removed, or until a joint is removed. In some embodiments, the determination of the etching end point for a specific etching process parameter can be performed by modeling and / or trial and error methods for the geometry and contours of specific features and the amount of deposited tungsten being etched. Of it. In some embodiments, the processing chamber may be provided with various sensors to perform in-situ measurements to determine the degree of removal. Examples of in situ measurements include optical microscopy and X-ray fluorescence analysis to determine film thickness. In addition, infrared (IR) spectroscopy can be used to detect the amount of tungsten fluoride (WF _X ) or other by-products generated during etching. In some embodiments, a bottom layer can be used as an etch stop layer. Optical emission spectroscopy (OES) can also be used to monitor etching.

In addition, according to various embodiments, the shape retention of the etching operation can be adjusted. Conformal etching refers to those in which the material is uniformly removed from the entire feature. The method for adjusting the shape retention of etching is as described above. In some embodiments, adjusting etch conformality may include operating under / without a mass transfer restriction system. In this system, the removal rate within a feature is affected by the amount and / or relative composition of different etch material compositions that diffuse into the feature (eg, initial etch material, active etchant species, and recombined etchant). Species). In some embodiments, the etch rate depends on the concentration of various etchant components at different locations within the feature. I should note that the terms "etch" and "remove" are used interchangeably in this article.

In some embodiments, groove etching may be performed in one, two, or more etching operations. For example, in a first operation, a rapid process is performed to remove tungsten in the field, followed by a more finely controlled process to etch and control the depth of the grooves. In one example, higher temperatures, higher etchant flow rates, and, for plasma-based etching, higher plasma power may be used. For faster etch, examples of etch rates may be between about 10 Å / sec and about 50 Å / sec. Lower etchant flow rates can be used for slower, more controlled processes and, for plasma-based etching, lower plasma power can be used. Depending on the desired etch selectivity relative to the underlying layer, the temperature during the controlled etch may or may not be lower than the temperature during the faster etch process. Examples of etch rates may be between about 3 Å / second-about 20 Å / second or for controlled etch, between about 3 Å / second-about 10 Å / second. device

Any suitable chamber can be used to implement this novel method. Examples of deposition equipment include various systems, such as ALTUS and ALTUS Max at Novellus Systems, San Jose, California, or any of a variety of other commercially available processing systems.

FIG. 9 shows a schematic diagram of an apparatus 900 for processing a portion of a processed semiconductor substrate according to some embodiments. The device 900 includes a chamber 918 having a support 920, a showerhead 914, and an in-situ plasma generator 916. The device 900 also includes a system controller 922 to receive inputs and / or provide control signals to various devices.

The etchant and, in some embodiments, argon, helium, and other inert gases, are supplied from a source 902 to a remote plasma generator 906, which may be a storage tank. Any suitable remote plasma generator may be used to activate the etchant before introducing the etchant into the chamber 918. For example, remote plasma cleaning (RPC) components from MKS Instruments of Andover, Andover, Mass., Such as ASTRON® i Type AX7670, ASTRON® e Type AX7680, ASTRON® ex Type AX7685, ASTRON® hf- s Type AX7645. The RPC component is usually a self-contained device that generates a weakly free plasma using the supplied etchant. The high-power RF generator embedded in the RPC component provides energy to the electrons in the plasma. This energy is then transferred to neutral etchant molecules, resulting in a temperature of the order of 2000K, which causes thermal dissociation of these molecules. Due to the high RF energy of the RPC device and its special channel geometry, the RPC device can dissociate more than 60% of the input molecules, causing the gas to adsorb most of this energy.

In some embodiments, the etchant flows from the remote plasma generator 906 through the connection line 908 into the chamber 918, and the mixture is distributed through the shower head 914 in the chamber. In other embodiments, the etchant flows directly into the chamber 918, bypassing the distal plasma generator 906 completely (eg, the system 900 does not include such a generator). Alternatively, for example, when the etchant flows into the chamber 918, the remote plasma generator 906 may be turned off, because activation of the etchant is not necessary.

The shower head 914 or the base 920 usually has an internal plasma generator 916 connected thereto. In one example, the generator 916 is a high frequency (HF) generator capable of providing between about 0 W and 10,000 W between a frequency of 1 MHz and 100 MHz. In a more specific embodiment, the high frequency generator may transmit between approximately 0 W and 5,000 W at approximately 13.56 MHz. The RF generator 916 may generate an in-situ plasma to facilitate the removal of the initial tungsten layer. In some embodiments, the radio frequency generator 916 is not used during the removal operation of the process.

The chamber 918 may include a sensor 924 for sensing various processing parameters, such as the degree of deposition, concentration, pressure, temperature, and the like. During processing, the sensor 924 may provide information on chamber conditions to the system controller 922. Examples of the sensor 924 include a mass flow controller, a pressure sensor, a thermocouple, and the like. The sensor 924 may also include an infrared detector or an optical detector to monitor the presence of gas in the chamber and control measures.

Deposition and selective removal operations produce various volatile species evacuated from the chamber 918. Furthermore, the treatment is performed in the chamber 918 at a specific predetermined pressure level. Both functions are accomplished using a vacuum outlet 926, which can be a vacuum pump.

Tungsten-containing precursors, and processing chemicals can enter the chamber from showerhead 914, exposing the substrate on the support 920 to the precursors or processing chemicals during various embodiments.

In some embodiments, the system controller 922 is used to control processing parameters. The system controller 922 typically includes one or more memory devices and one or more processors. The processor may include a CPU or computer, analog and / or digital input / output connections, a progressive motor control board, and so on. There is usually a user interface connected to the system controller 922. The user interface can include graphical software displays that display screens, equipment, and / or processing conditions, as well as user input devices such as pointing devices, keyboards, touch screens, microphones, and more.

In some embodiments, the system controller 922 controls substrate temperature, etchant flow rate, power output of the remote plasma generator 906 and / or in-situ plasma generator 916, internal pressure in the chamber 918, and processing reduction Flux flow rate, annealing temperature, interruption of second body tungsten deposition to flow processing chemicals into the chamber, and other processing parameters. The controller parameters are related to the processing conditions, such as the timing of each operation, the pressure in the chamber, the substrate temperature, the etchant flow rate, and so on. These parameters are provided to the user in the form of a recipe and can be entered using the user interface. Signals for monitoring and processing can be provided by analog and / or digital input connections to the system controller 922. The signals used to control the processing are output to the analog and digital output terminals of the device 900.

The system controller 922 executes system control software, which includes multiple sets of instructions for controlling time, gas mixtures, chamber pressure, chamber temperature, and other parameters for specific processes. In some embodiments, other computer programs stored on a memory device connected to the controller may be used. Alternatively, the control logic can be written directly into the controller. Application-specific integrated circuits (ASICs), programmable logic devices (such as field-programmable gate arrays (FPGAs)), and the like can be used for these purposes. In the following description, regardless of whether "software" or "code" is used, similarly hard-written logic can be used for its position.

The computer code used to control the processes in the processing sequence can be written in any conventional computer-readable programming language: for example, a combination language, C programming language, C ++ programming language, Pascal, Fortran, or others. The compiled object code or script is executed by the processor to perform the tasks identified in the program. The system software can be designed or configured in many different ways. For example, various conventional or control articles of various chamber elements can be written to control the operation of the necessary chamber elements to perform the described processes. Examples of programs or program sections for this purpose include processing gas control codes, pressure control codes, and plasma control codes. The system control logic can be configured in any suitable way. Generally speaking, logic can be designed or configured in hardware and / or software. The instructions for controlling the driving circuit can be written or provided as software. Instructions can be provided "programmatically". This stylization is known to include any form of logic, including logic dying in a digital signal processor, special application integrated circuits, and other devices with specific calculation algorithms that are executed as hardware. The system control software can be written in any suitable computer-readable programming language.

FIG. 10A shows an example of a multi-station device 1000. The apparatus 1000 includes a processing chamber 1001 and one or more cassettes 1003 (eg, a Front Opening Unified Pod) for holding a substrate to be processed and a substrate that has been processed. The chamber 1001 may have several stations, such as two stations, three stations, four stations, five stations, six stations, seven stations, eight stations, ten stations, or any other number of stations. The number of such stations is usually determined by the complexity of the processing operations and the number of such operations that can be performed in a shared environment. FIG. 10A illustrates a processing chamber 1001 including six stations labeled 1011 to 1016. All stations in a multi-station apparatus 1000 having a single processing chamber 1003 are exposed to the same pressure environment. However, each station may have a designated reactant distribution system and localized plasma and heating conditions implemented by a dedicated plasma generator and support, such as those depicted in FIG. 9.

The substrate to be processed is loaded into the station 1011 through one of the plurality of cassettes 1003 through the load lock chamber 1005. The external robot arm 1007 can be used to transfer the substrate from the cassette 903 into the load lock chamber 1005. In the depicted embodiment, there are two independent load lock chambers 1005. These are usually equipped with a substrate transfer device to move the substrate from the load lock chamber 1005 (once the pressure is balanced to a level corresponding to the internal environment of the processing chamber) into station 1011 and back from station 1016 to The load lock chamber 1005 is removed from the processing chamber 1003. The mechanical device 1009 is used to transfer substrates between the processing stations 1011 to 1016 and to support some substrates during the processing described below.

In some embodiments, one or more stations may be reserved to heat the substrate. The stations may have a heating lamp (not shown) positioned on the substrate and / or a heating base supporting the substrate similar to that shown in FIG. 9. For example, the station 1011 may receive a substrate from a load lock chamber and use it to preheat the substrate before further processing the substrate. Other stations can be used to fill features with high aspect ratios, including deposition and etching operations.

After the substrate is heated or otherwise processed at station 1011, the substrate system is successively moved to processing stations 1012, 1013, 1014, 1015, and 1016, which may or may not be sequentially configured. The multi-station device 1000 can be used to expose all stations to the same stress environment. As such, the substrates are transferred from station 1011 to other stations in chamber 1001 without the need for a transfer port such as a load lock chamber.

In some embodiments, one or more stations may be used to fill the feature with a tungsten-containing material. For example, station 1012 may be used for an initial deposition operation, and station 1013 may be used for a corresponding selective removal operation. In an embodiment where the deposition removal cycle is repeated, station 1014 may be used for another deposition operation and station 1015 may be used for another removal operation. Station 1016 can be used for the final fill operation. I should understand that any configuration specified for a particular processing (heating, filling, and removal) station can be used. In some embodiments, one station may be used to deposit tungsten, while other stations are used to etch operations that are used in groups of each feature size targeted by several deposition-etch-deposition schemes. In some embodiments, one station may be used to deposit the first body tungsten layer, another station may be used for the etching operation, and the third station may be used to deposit and process the second body, so that the wafer is during the second body deposition and process. The department is in one stop.

As an alternative to the multi-station equipment described above, the method can be implemented in a single substrate chamber or in a multi-station chamber that processes (one or more) substrates in a single processing station in batch mode (ie, discontinuously). In this embodiment of the invention, the substrate is loaded into the chamber and positioned on the base of a single processing station (whether it is a device with only one processing station or a multi-station device operating in batch mode) ). The substrate can then be heated and deposited. The processing conditions in the chamber can then be adjusted, followed by selective removal of the deposited layer. This process can continue with one or more deposition-removal cycles, and the final filling operation is performed on the same station. Alternatively, a single station device may be used first to perform only one of the new methods (eg, deposition, selective removal, final fill) on several wafers, after which the substrate may be returned to the same station or moved To a different station (for example, a station of a different device) to perform one or more of the remaining operations.

FIG. 10A also illustrates an embodiment of a system controller 1050 for controlling processing conditions and the hardware state of the processing tool 1000. The system controller 1050 may include one or more memory devices 1056, one or more mass storage devices 1054, and one or more processors 1052. The processor 1052 may include a CPU or a computer, analog and / or digital input / output connections, a progressive motor control board, and the like.

In some embodiments, the system controller 1050 controls all activities of the processing tool 1000. The system controller 1050 executes the system control software 1058 stored in the mass storage device 1054. The system control software 1058 is loaded into the memory device 1056 and executed on the processor 1052. Alternatively, the control logic may be written in the controller 1050. Alternatively, the control logic can be written directly into the controller. Special application integrated circuits, programmable logic devices (such as field-programmable gate arrays (FPGAs)), and the like can be used for these purposes. In the following description, regardless of whether "software" or "code" is used, similarly hard-written logic can be used for its position. The system control software 1058 may include multiple sets of instructions for controlling time, gas mixture, amount of subsaturated gas flow, chamber and / or station temperature, wafer temperature, target power level, RF power level, substrate support Seat, chuck and / or receptacle locations, processing chemicals, etching chemicals for each feature size group, and other parameters performed by a particular process of the processing tool 1000. The system control software 1058 may be configured in any suitable manner. For example, various processing tool components may be written as sub-regular or control objects to control the operation of the necessary processing tool components for performing various processing programs. The system control software 1058 can be encoded in any suitable computer-readable programming language.

In some embodiments, the system control software 1058 may include input / output control (IOC) sequence instructions for controlling the various parameters described above. In some embodiments, other computer software stored in the mass storage device 1054 and / or a memory device 1056 connected to the system controller 1050 may be used. Examples of programs or program sections for this purpose include substrate positioning programs, process gas control programs, pressure control programs, heater control programs, and plasma control programs.

The substrate positioning program may include code for processing tool components that are used to load the substrate to the support 1001 and control the spacing between the substrate and other components of the processing tool 1000.

The process gas control program may include components for controlling the composition of the gas (such as TMA, ammonia, and purge gas as described herein) and flow rates, and optionally for flow before deposition to stabilize the pressure within the processing station. Code for gas to one or more processing stations. The pressure control program may include a code for controlling the pressure in the processing station, which is through, for example, adjusting a throttle valve in the exhaust system of the processing station, gas flow into the processing station, and the like.

The heater control program may include a code for controlling a current to heat a heating unit for heating the substrate. Alternatively, the heater control program may control the delivery of a heat transfer gas (such as helium) to the substrate.

The plasma control program may include a code for setting a radio frequency power level applied to processing electrodes in one or more processing stations according to embodiments described herein.

The pressure control program may include a code for maintaining the pressure in the reaction chamber according to embodiments described herein.

In some embodiments, there is usually a user interface connected to the system controller 1050. The user interface may include graphical software displays that display screens, devices, and / or processing conditions, as well as user input devices such as pointing devices, keyboards, touch screens, microphones, and so on.

In some embodiments, the parameters adjusted by the system controller 1050 may be related to processing conditions. Non-limiting examples include process gas composition and flow rate, temperature, pressure, plasma conditions (eg, RF bias power levels), pressure, temperature, and the like. These parameters can be provided to the user in the form of a recipe and can be entered using the user interface.

Signals for monitoring processing can be provided by analog and / or digital input connections of the system controller 1050 from various processing tool sensors. The signals used to control this processing can be output on the analog and digital output connections of the processing tool 1000. Non-limiting examples of process tool sensors that can be monitored include mass flow controllers, pressure sensors (such as pressure gauges), thermocouples, and the like. Properly programmed feedback and control algorithms can be used with data from these sensors to maintain processing conditions.

The system controller 1050 may provide program instructions for implementing the above-mentioned deposition process. These program instructions can control various processing parameters, such as DC power level, RF bias power level, pressure, temperature, etc.These instructions can control parameters for in-situ deposition of film stacks according to various embodiments described herein. operating.

The system controller typically includes one or more memory devices and one or more processors to execute instructions to enable the device to perform the method according to the disclosed embodiments. A machine-readable medium for controlling processing operations according to the disclosed embodiments may be connected to the system controller.

The equipment / processing described above can be used in conjunction with lithographic patterning tools or processes, such as for manufacturing or processing semiconductor components, displays, LEDs, photovoltaic panels and the like. Although not necessarily, these tools / treatments will typically be used or performed together in a common processing facility. The lithographic patterning of the film usually includes part or all of the following steps, each step can be achieved using some possible tools: (1) using spin coating or spraying tools to apply photoresist to the workpiece, that is, the substrate; ( 2) Use a hot plate or furnace or UV curing tool to cure the photoresist; (3) Use a tool such as a wafer stepper to expose the photoresist to visible light or ultraviolet or X-rays; (4) develop the photoresist to Selectively remove the photoresist to pattern it using a tool such as a wet table; (5) use dry or plasma-assisted etching tools to transfer the photoresist pattern to the underlying film or workpiece; (6) use such as RF or Microwave plasma photoresist stripping tool to remove photoresist.

FIG. 10B is a schematic diagram of a multi-chamber device 1020 that can be used in accordance with certain embodiments. As shown, the device 1020 has three independent chambers 1021, 1023, and 1025. Each of these chambers is shown as having two supports. It should be understood that a device may have any number of chambers (eg, one, two, three, four, five, six, etc.), and each chamber may have any number of supports (eg , One, two, three, four, five, six, etc.). Each chamber 1021-1025 has its own pressure environment and is not shared with other chambers. Each chamber may have one or more corresponding transfer ports (such as a load lock chamber). The device may also have a common substrate processing robot arm 1027 for transferring one or more cassettes 1029 between substrates between transfer ports.

As mentioned above, a separate chamber can be used to deposit tungsten-containing materials and to selectively remove these deposited materials in subsequent operations. These two operations are performed in different chambers, respectively, which can greatly improve the processing speed by maintaining the same environmental conditions in each chamber. In other words, the chamber does not need to change its environment to change from the conditions used for deposition to the conditions used for selective removal and recovery, which may involve different precursors, different processing chemicals, different temperatures, pressures, and other processing parameter. In some embodiments, transferring partially processed semiconductor substrates between two or more different chambers is faster than changing the environmental conditions of the chambers. in conclusion

Although the foregoing embodiments have been described in detail for the sake of clarity, it is obvious that we can implement certain changes and modifications within the scope of the appended claims. I should note that there are still many alternative ways of implementing the processes, systems, and equipment of this embodiment. Therefore, this embodiment should be considered as illustrative and not restrictive, and the embodiment is not limited to the details set forth herein.

102‧‧‧Feature Department
104‧‧‧Feature Department
120‧‧‧operation phase
122‧‧‧ Operation Phase
140‧‧‧operation phase
142‧‧‧operation phase
211‧‧‧operation
213‧‧‧ Operation
215‧‧‧Operation
310‧‧‧ Operation
312‧‧‧operation
314‧‧‧ Operation
314a‧‧‧operation
314b‧‧‧operation
314c‧‧‧ Operation
401‧‧‧operation
403‧‧‧operation
405‧‧‧operation
407‧‧‧ Operation
409‧‧‧operation
411‧‧‧operation
413‧‧‧operation
415‧‧‧operation
417‧‧‧operation
501‧‧‧Feature Department
502‧‧‧Feature Department
515‧‧‧ protrusion
551‧‧‧Constriction
701‧‧‧operation phase
703‧‧‧operation stage
705‧‧‧operation phase
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709‧‧‧operation phase
801‧‧‧operation stage
803‧‧‧operation phase
805‧‧‧operation phase
807‧‧‧operation phase
809‧‧‧operation phase
900‧‧‧ Equipment
902‧‧‧ Source
906‧‧‧Remote Plasma Generator
908‧‧‧cable
914‧‧‧Sprinkler
916‧‧‧In-situ Plasma Generator
918‧‧‧chamber
920‧‧‧bearing
922‧‧‧System Controller
924‧‧‧Sensor
926‧‧‧Vacuum outlet
1000‧‧‧multi-station equipment
1001‧‧‧Processing chamber
1003‧‧‧ Cassette
1005‧‧‧Load lock room
1007‧‧‧External Robot Arm
1009‧‧‧Mechanical device
1011‧‧‧Processing Station
1012‧‧‧Processing Station
1013‧‧‧Processing Station
1014‧‧‧Processing Station
1015‧‧‧Processing Station
1016‧‧‧Processing Station
1020‧‧‧ Equipment
1021‧‧‧ Chamber
1023‧‧‧ Chamber
1025‧‧‧ Chamber
1027‧‧‧Substrate Processing Robot
1029‧‧‧ Cassette
1050‧‧‧System Controller
1052‧‧‧Processor
1054‧‧‧Large-capacity storage device
1056‧‧‧Memory device
1058‧‧‧System Control Software

FIG. 1 is a schematic diagram of small features and large features at each stage of deposition and etching.

FIG. 2 is a processing flowchart of a method of depositing tungsten in a feature.

FIG. 3 and FIG. 4 are processing flowcharts for executing the method according to the disclosed embodiment.

FIG. 5 is a schematic diagram of a characteristic part at each stage of the etching, which shows the conformal adjustment of the etching.

FIG. 6 is a graph showing tungsten etching rates for different etchant flows, which is a function of etching temperature.

FIG. 7 is a schematic diagram of a small feature at each stage of feature filling using the disclosed embodiment.

FIG. 8 is a schematic diagram of a large-scale feature at each stage of feature filling using the disclosed embodiment.

FIG. 9 is a schematic diagram of a chamber for performing a method according to the disclosed embodiment.

10A and 10B are schematic diagrams of a multi-chamber device for performing a method according to a disclosed embodiment.

Claims (20)

A method for processing a semiconductor substrate includes: (i) providing a substrate including a plurality of features having openings of different sizes, the features including a first feature and a second feature, wherein the first feature Separated from and separated from the second feature, and wherein the first feature has a smaller opening than the second feature; (ii) depositing a first body tungsten layer into the features to partially fill them The features; (iii) performing a non-conformal etch of the first body tungsten layer to leave an etched tungsten layer in the features, including removing from the top of the first feature compared to More tungsten inside the first feature; (iv) depositing a second bulk tungsten layer on the etched tungsten layer; and (v) after the first feature is completely filled with tungsten and after the Before the second feature is completely filled with tungsten, the surface of the second body tungsten layer is processed. For example, the method for processing a semiconductor substrate according to item 1 of the application, wherein processing the surface of the second body tungsten layer includes exposing the substrate to a reducing agent. For example, the method for processing a semiconductor substrate according to item 2 of the application, wherein the reducing agent is selected from the group consisting of borane, silane, and hydrogen. For example, the method for processing a semiconductor substrate according to item 1 of the patent application, wherein processing the surface of the second body tungsten layer includes exposing the substrate to nitrogen. For example, the method for processing a semiconductor substrate according to item 1 of the application, wherein processing the surface of the second body tungsten layer includes annealing the substrate. For example, the method for processing a semiconductor substrate according to item 1 of the application, wherein processing the surface of the second body tungsten layer includes depositing a barrier layer on the substrate. The method for processing a semiconductor substrate according to item 6 of the patent application, wherein the barrier layer comprises tungsten nitride. For example, the method for processing a semiconductor substrate according to item 1 of the application, wherein the openings of different sizes include openings between about 1 nm and about 1 micron. For example, the method for processing a semiconductor substrate according to item 1 of the patent application, wherein the features include features having about 20 openings of different sizes. A method for processing a semiconductor substrate, comprising: (i) providing a substrate including a plurality of features, the features having at least one set of smaller features and at least one set of larger features, wherein the smaller features and the The larger features are separated and separated; (ii) a first body tungsten layer is deposited in the features; (iii) a portion of the first body tungsten layer is etched at a first temperature to leave An etched first body tungsten layer; (iv) depositing a second body tungsten layer on the etched first body tungsten layer to fill the at least one group of smaller features and at least partially fill the at least one group Larger features; (v) etching a portion of the second bulk tungsten layer at a second temperature to leave an etched second bulk tungsten layer; and (vi) depositing a third bulk tungsten layer on the The etched second body tungsten layer is used to fill the at least one group of larger features. For example, the method for processing a semiconductor substrate according to claim 10, wherein the first temperature is lower than the second temperature. For example, the method for processing a semiconductor substrate according to claim 10, wherein the first temperature is higher than the second temperature. For example, the method for processing a semiconductor substrate according to claim 10, wherein each of the at least one set of smaller features and the at least one set of larger features includes a plurality of features having at least one feature size. For example, the method for processing a semiconductor substrate according to claim 10, wherein each of the at least one small feature includes a feature and each of the at least one larger feature includes a feature. For example, the method for processing a semiconductor substrate according to claim 10, wherein the at least one set of smaller features includes a plurality of features, and the features have an opening between about 1 nm and about 2 nm. For example, the method for processing a semiconductor substrate according to item 10 of the patent application, wherein the at least one group of larger features includes a plurality of features, and the features have an opening between about 100 nm and about 1 micron. For example, the method for processing a semiconductor substrate according to claim 10, wherein the key feature of the largest feature in the at least one group of larger features is the largest feature in the at least one group of smaller features. Have at least five times the critical dimension. An apparatus for processing a semiconductor substrate includes: a processing chamber including a shower head and a substrate holder; and a controller having at least one processor and a memory, wherein the at least one processor and The memories are communicatively connected to each other, the at least one processor is at least operatively connected to a flow control hardware, and the memory system stores machine-readable instructions for: introducing a tungsten-containing precursor and A reducing agent is deposited into the chamber to deposit a first main body tungsten layer; a fluorine-containing etchant is introduced into the chamber to etch a portion of the first main body tungsten layer to leave an etched first main body tungsten layer at A plurality of features on a substrate; introducing the tungsten-containing precursor and the reducing agent into the chamber to partially deposit a second body tungsten layer; temporarily terminating the deposition of the second body tungsten layer at a predetermined time; introducing A processing reagent to the chamber; terminating the introduction of the processing reagent into the chamber; and continuing to introduce the tungsten-containing precursor and the reducing agent into the chamber to deposit the remaining second bulk tungsten layer. For example, an apparatus for processing a semiconductor substrate according to item 18 of the application, wherein the processing reagent is selected from the group consisting of borane, silane, and hydrogen. For example, the device for processing a semiconductor substrate according to item 18 of the patent application, wherein the predetermined time is a time during which small features on the substrate are filled.