Semiconductor structure and method for forming the same

Abstract

The present invention provides a semiconductor structure and a method for forming the same, the method comprising: providing a substrate; forming a dielectric layer on the substrate, wherein the dielectric layer has a groove; forming a barrier layer on the dielectric layer and the surface of the groove; forming a diffusion barrier layer on the barrier layer; forming a first tungsten seed layer on the diffusion barrier layer; forming a second tungsten seed layer on the first tungsten seed layer; and forming a metal tungsten block on the second tungsten seed layer; wherein the first tungsten seed layer does not contain boron, and the second tungsten seed layer contains boron. The method of the present invention can effectively solve the problem in the prior art that the tungsten film formed by deposition using borane as a precursor is easy to peel off in the subsequent CMP process.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to a semiconductor structure and a forming method thereof. Background Art

[0002] With the continuous development of semiconductor technology, the deposition of metal tungsten (CVD W) by chemical vapor deposition and / or the deposition of metal tungsten (ALD W) by atomic vapor deposition has good step coverage and is widely used in the manufacture of metal interconnect filling layers in semiconductor devices. The reducing precursors used in the CVD W or ALD W process are mainly silane (SiH4), borane (B2H6) and hydrogen (H2). Usually, SiH4 or B2H6 is used to reduce tungsten hexafluoride (WF6) in the initial nucleation stage to form a thin tungsten seed layer. Compared with the SiH4 precursor, the W grain size formed by the nucleation of the B2H6 precursor is larger, and the resistivity of the W film is significantly reduced. However, the disadvantage of B2H6 as a precursor is that the formed W film has poor adhesion, which can easily cause the W film to peel off from the substrate in the subsequent chemical mechanical polishing (CMP) process, forming defects, thereby affecting the product yield.

[0003] Therefore, a new semiconductor structure and a method for forming the same are urgently needed to overcome the above problems.

[0004] It should be noted that the information disclosed in the aforementioned background technology section is only used to enhance the background understanding of the present invention, and therefore it may include information that does not constitute the prior art known to ordinary technicians in the field. Summary of the invention

[0005] The purpose of the present invention is to provide a semiconductor structure and a method for forming the same, so as to solve the problem that when borane (B2H6) is used as a precursor for CVD W or ALD W in the prior art, the formed tungsten film is easily peeled off in the subsequent CMP process.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The present invention provides a method for forming a semiconductor structure, comprising:

[0008] providing a substrate;

[0009] forming a dielectric layer on the substrate, wherein the dielectric layer has a groove;

[0010] forming a barrier layer on the dielectric layer and the surface of the trench;

[0011] forming a diffusion barrier layer on the barrier layer;

[0012] forming a first tungsten seed layer on the diffusion barrier layer;

[0013] forming a second tungsten seed layer on the first tungsten seed layer; and

[0014] forming a metal tungsten block on the second tungsten seed layer;

[0015] The first tungsten seed layer does not contain boron, and the second tungsten seed layer contains boron.

[0016] According to one embodiment of the present invention, the diffusion barrier layer is a silicon atomic layer.

[0017] According to one embodiment of the present invention, the forming method specifically comprises:

[0018] Passing silane gas to pre-treat the surface of the barrier layer, and performing a deposition reaction to form the silicon atomic layer;

[0019] Introducing a first gas onto the silicon atomic layer to cause a deposition reaction to form the first tungsten seed layer;

[0020] Introducing a second gas and a borane gas onto the first tungsten seed layer to form the second tungsten seed layer by a deposition reaction;

[0021] Introducing a third gas and hydrogen gas onto the second tungsten seed layer to form the metal tungsten bulk material by deposition reaction;

[0022] The deposition is chemical vapor deposition or atomic vapor deposition, and the first gas, the second gas and the third gas are all tungsten hexafluoride.

[0023] According to one embodiment of the present invention, the silane gas is introduced at a flow rate of 30 to 300 sccm for reaction for 2 to 10 seconds to form the silicon atomic layer.

[0024] According to one embodiment of the present invention, the first gas is introduced at a flow rate of 30 to 300 sccm for a reaction time of 0.1 to 10 seconds to form the first tungsten seed layer.

[0025] According to one embodiment of the present invention, the second gas is introduced at a flow rate of 30 to 300 sccm, and the borane gas is introduced at a flow rate of 30 to 300 sccm to form the second tungsten seed layer.

[0026] According to one embodiment of the present invention, the second tungsten seed layer is formed by atomic vapor deposition, and the borane gas and the second gas are introduced sequentially for 2 to 10 pulse cycles.

[0027] According to one embodiment of the present invention, one of the pulse cycles comprises:

[0028] After the borane gas is introduced for 1 to 5 seconds, an inert gas is purged for 3 to 5 seconds;

[0029] After the second gas is introduced for 0.2 to 1 second, an inert gas purge is performed for 2 to 5 seconds.

[0030] According to one embodiment of the present invention, the flow rate of the third gas is 30-300 sccm, and the flow rate of the hydrogen gas is 200-20000 sccm.

[0031] According to one embodiment of the present invention, the chemical vapor deposition or atomic vapor deposition is performed at a temperature of 280 to 400° C. and a pressure of 40 torr to 300 torr.

[0032] According to one embodiment of the present invention, the thickness of the diffusion barrier layer is 0.1-5 nm, the thickness of the first tungsten seed layer is 0.1-5 nm, and the thickness of the second tungsten seed layer is 2-10 nm.

[0033] According to one embodiment of the present invention, the barrier layer is a titanium nitride layer, a mixed layer of titanium nitride and titanium, or a tungsten nitride layer.

[0034] According to one embodiment of the present invention, the material of the dielectric layer is silicon dioxide, and the material of the substrate is selected from one or more of aluminum, copper, titanium nitride, cobalt silicide and silicon.

[0035] The present invention also provides a semiconductor structure, comprising:

[0036] substrate;

[0037] a dielectric layer formed on the substrate;

[0038] a trench formed in the dielectric layer;

[0039] A barrier layer formed on the dielectric layer and the surface of the groove;

[0040] a diffusion barrier layer formed on the barrier layer;

[0041] a first tungsten seed layer formed on the diffusion barrier layer;

[0042] a second tungsten seed layer formed on the first tungsten seed layer;

[0043] A metal tungsten block is formed on the second tungsten seed layer;

[0044] The first tungsten seed layer does not contain boron, and the second tungsten seed layer contains boron.

[0045] According to one embodiment of the present invention, the thickness of the diffusion barrier layer is 0.1-5 nm; the thickness of the first tungsten seed layer is 0.1-5 nm; and the thickness of the second tungsten seed layer is 2-10 nm.

[0046] According to one embodiment of the present invention, the diffusion barrier layer is a silicon atomic layer.

[0047] According to one embodiment of the present invention, the barrier layer is a titanium nitride layer, a mixed layer of titanium nitride and titanium, or a tungsten nitride layer.

[0048] According to the description of the above technical solution, the beneficial effects of the present invention are:

[0049] The semiconductor structure and the formation method thereof provided by the present invention can be used to solve the problem in the prior art that when borane (B2H6) is used as a precursor for CVD W or ALD W, the formed tungsten film is easily peeled off from the dielectric layer together with the barrier layer. Before the borane precursor and tungsten hexafluoride gas are introduced into the reaction chamber, the surface of the barrier layer is pretreated to form a diffusion barrier layer, which can effectively block the diffusion of boron. The first tungsten seed layer formed on the diffusion barrier layer can further block the diffusion of boron, thereby improving the problem of poor adhesion between the B2H6-base W and the barrier layer on the dielectric layer, and effectively reducing the risk of the W film peeling off during the subsequent CMP planarization process. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to make the embodiments of the present invention easier to understand, the following is a detailed description with reference to the attached drawings. It should be noted that according to standard examples in the industry, the various components are not necessarily drawn to scale and are only used for illustration purposes. In fact, in order to make the discussion clear and understandable, the size of the various components can be arbitrarily enlarged or reduced.

[0051] Figure 1 A schematic cross-sectional view of a semiconductor structure;

[0052] Figure 2a-2b Schematic diagram of each stage of the traditional B2H6-base WCVD process;

[0053] Figure 3 is a schematic cross-sectional view of a semiconductor structure having a defective layer;

[0054] Figure 4 A process flow chart showing a semiconductor structure formation process according to one embodiment of the present invention;

[0055] Figure 5a to Figure 5h A schematic structural cross-sectional diagram of each stage of a process for forming a metal tungsten layer according to an embodiment of the present invention is shown.

[0056] The reference numerals are described as follows:

[0057] 100, 200: base

[0058] 101, 201: Dielectric layer

[0059] 102, 202: Groove

[0060] 103, 203: Obstruction layer

[0061] 104, 205: Metal tungsten layer

[0062] 104a: Tungsten seed layer

[0063] 105: Unknown layer

[0064] 204: Silicon Atomic Layer

[0065] 205a: first tungsten seed layer

[0066] 205b: Second tungsten seed layer

[0067] H: Height

[0068] D: Width

[0069] 11,50: Borane

[0070] 12, 13, 30, 40, 60: Tungsten hexafluoride

[0071] 20: Silane

[0072] 14,70: Hydrogen DETAILED DESCRIPTION

[0073] The following content provides many different embodiments or examples to implement different components of embodiments of the present invention. Specific examples of components and configurations are described below to simplify embodiments of the present invention. Of course, these are merely examples and are not intended to limit embodiments of the present invention. Embodiments of the present invention may repeat reference numerals and / or letters in various examples. This repetition is for the purpose of simplicity and clarity and is not itself used to specify the relationship between the various embodiments and / or configurations discussed. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present invention.

[0074] In an embodiment of the present invention, a component is formed on another component, connected to another component, and / or coupled to another component, which may include an embodiment in which the component is formed to directly contact another component, and may also include an embodiment in which an additional component is formed between these components so that these components are not in direct contact. Furthermore, in order to easily describe the relationship between one component and another component of an embodiment of the present invention, spatially related terms may be used herein, for example, "lower", "higher", "horizontally", "vertically", "above", "above", "below", "under", "upward", "downward", "top", "bottom", and other derived spatially related terms (e.g., "horizontally", "vertically", "upwardly", "downwardly", etc.). These spatially related terms are intended to cover different orientations of devices containing these components.

[0075] Figure 1 It is a schematic diagram of a semiconductor structure cross section. Figure 1 The semiconductor structure shown includes:

[0076] A substrate 100 and a dielectric layer 101 on the substrate 100, wherein the dielectric layer 101 has a groove 102, and a barrier layer 103 is provided on the surface of the dielectric layer 101 and the groove 102, wherein the dielectric layer includes but is not limited to silicon dioxide (SiO2), etc., and the material of the barrier layer 103 includes but is not limited to titanium nitride (TiN), a mixture of titanium nitride and titanium (Ti&TiN), etc. The cross-sectional height H of the groove 102 is about 40 to 4000 nm, and the bottom width D is 20 to 200 nm. A metal tungsten layer 104 is provided on the surface of the barrier layer 103, which is formed by ALD or CVD deposition using B2H6 as a precursor (B2H6-base WCVD / B2H6-base WALD).

[0077] Specifically, Figure 2a-2b Schematic diagram of each stage of the traditional B2H6-base WCVD process. Figure 2a-2b As shown, the conventional B2H6-base WCVD process first introduces B2H6 gas 11 and tungsten hexafluoride (WF6) 12 into the reaction chamber to deposit a W seed layer 104a on the barrier layer 103, wherein the thickness of the barrier layer 103 is about 2 to 20 nm, and the thickness of the tungsten seed layer 104a is about 2 to 10 nm. Then, tungsten hexafluoride gas 13 and hydrogen gas 14 are introduced to deposit tungsten bulk (Bulk W) until a Figure 1 The metal tungsten layer 104 shown has a thickness of about 10-100 nm, wherein the metal tungsten layer 104 includes a tungsten seed layer 104 a (not shown).

[0078] However, the disadvantage of using B2H6 as a precursor is that the metal tungsten layer formed has poor adhesion. The reason is that during the deposition process, B2H6 diffuses between the dielectric layer and the barrier layer and decomposes to form boron, or boron atoms diffuse into the dielectric layer and aggregate between the barrier layer, forming an unnecessary defect layer (unknown layer) 105 (such as Figure 3 When Figure 3 After the semiconductor structure shown is processed by the CMP process, the defect layer (unknown layer) 105 causes the adhesion between the barrier layer 103 and the dielectric layer 101 to deteriorate, and then in the subsequent chemical mechanical polishing (CMP) process, it is easy to cause the metal tungsten layer 104 and the barrier layer 103 to peel off from the dielectric layer 101, thereby forming defects and affecting the product yield.

[0079] To this end, the present invention provides a method for forming a semiconductor structure. Figure 4 A process flow chart of forming a semiconductor structure according to an embodiment of the present invention is shown, comprising:

[0080] providing a substrate;

[0081] forming a dielectric layer on the substrate, wherein the dielectric layer has a groove;

[0082] Forming a barrier layer on the dielectric layer and the surface of the groove

[0083] forming a diffusion barrier layer on the barrier layer;

[0084] forming a first tungsten seed layer on the diffusion barrier layer;

[0085] forming a second tungsten seed layer on the first tungsten seed layer; and

[0086] forming a metal tungsten block on the second tungsten seed layer;

[0087] The first tungsten seed layer does not contain boron, and the second tungsten seed layer contains boron.

[0088] As mentioned above, since the boron atoms in the boron-containing tungsten seed layer are easy to diffuse to the surface of the dielectric layer and form defects, the present invention forms a diffusion barrier layer on the basis of the barrier layer to block the diffusion of boron. The barrier layer includes but is not limited to a titanium nitride (TiN) layer, a mixed layer of titanium nitride and titanium (Ti&TiN) or a tungsten nitride (WNx) layer. The barrier layer can block part of the boron diffusion, and can also allow W to be deposited and adhered to the surface of the barrier layer to play an adhesion role. However, due to the defects in the barrier layer, its film layer is not dense enough, so that part of the boron diffuses into the interface between the dielectric layer and the barrier layer, thereby causing the adhesion between the dielectric layer and the barrier layer to decrease. By adding a diffusion barrier layer on the barrier layer, the diffusion barrier layer can provide a nucleation position for the subsequent first tungsten seed layer on the one hand to reduce the time of crystal nucleus incubation, and on the other hand, the diffusion barrier layer can fill the defects of the barrier layer and prevent the reaction gas from diffusing to the barrier layer, thereby reducing the risk of B2H6-base W and the barrier layer peeling off from the surface of the dielectric layer during the subsequent CMP planarization process.

[0089] In some embodiments, the diffusion barrier layer is a silicon atomic layer.

[0090] In some embodiments, the diffusion barrier layer has a thickness of 0.1-5 nm, the first tungsten seed layer has a thickness of 0.1-5 nm, and the second tungsten seed layer has a thickness of 2-10 nm.

[0091] In some embodiments, the above forming method specifically includes:

[0092] Passing silane gas to pre-treat the barrier layer, and performing a deposition reaction to form the silicon atomic layer;

[0093] Introducing a first gas onto the silicon atomic layer to cause a deposition reaction to form the first tungsten seed layer;

[0094] Introducing a second gas and borane (B2H6) gas onto the first tungsten seed layer to form the second tungsten seed layer by deposition reaction;

[0095] Introducing a third gas and hydrogen gas onto the second tungsten seed layer to form the metal tungsten bulk material by deposition reaction;

[0096] The deposition is chemical vapor deposition or atomic vapor deposition, and the first gas, the second gas and the third gas are all tungsten hexafluoride (WF6).

[0097] In the above process, the silicon atomic layer plays two main roles: one is to provide nucleation sites to reduce the incubation time of the crystal nucleus; the other is to use the amorphous Si generated by SiH4 to fill the defects of the barrier layer, reduce the diffusion of B2H6 and WF6 to the bottom of the barrier layer, and thus prevent the problem of metal tungsten or metal tungsten and the barrier layer from easily falling off from the dielectric layer. In addition, since no other impurities (such as boron) are introduced during the formation of the second tungsten seed layer, the resistance of the formed tungsten layer is relatively low.

[0098] Figure 5a to Figure 5h The schematic diagram of the structure cross section of each stage of the process of forming a metal tungsten layer in one embodiment of the present invention is shown. The semiconductor structure includes a substrate 200, a dielectric layer 201, a groove 202, and a barrier layer 203 located on the surface of the dielectric layer 201 and the groove 202. Figure 5a As shown, after forming the barrier layer 203, firstly, silane (SiH4) gas 20 is introduced into the reaction chamber for pretreatment, and a thin silicon atomic layer 204 is formed on the barrier layer (see Figure 5b ), the thickness of the silicon atomic layer 204 is about 0.1 to 5 nm. Then, Figure 5c As shown, a first gas of tungsten hexafluoride 30 is introduced onto the formed silicon atom layer 204 to form a first tungsten seed layer 205a (see Figure 5d ), the thickness of the first tungsten seed layer 205a is about 0.1-5 nm. Figure 5e As shown, a second gas of tungsten hexafluoride 40 and a borane (B2H6) gas 50 are introduced onto the first tungsten seed layer 205a to form a second tungsten seed layer 205b (see Figure 5f ), the thickness of the second tungsten seed layer is 2-10 nm. Then, a third gas of tungsten hexafluoride 60 and hydrogen 70 is introduced onto the second tungsten seed layer 205b (such as Figure 5g ), a tungsten bulk material (bulkW) (not shown) is reactively deposited until the required thickness to fill the trench is reached, and the thickness of the metal tungsten layer 205 finally formed is about 10 to 100 nm (see Figure 5h ), wherein the metal tungsten layer 205 includes the aforementioned first tungsten seed layer, the second tungsten seed layer and a tungsten bulk material.

[0099] In some embodiments, the silane gas is introduced at a flow rate of 30 to 300 sccm for a reaction of 2 to 10 seconds to form the silicon atomic layer. In some embodiments, the first gas is introduced at a flow rate of 30 to 300 sccm for a reaction of 0.1 to 10 seconds to form the first tungsten seed layer. In some embodiments, the second gas is introduced at a flow rate of 30 to 300 sccm, and the borane gas is introduced at a flow rate of 30 to 300 sccm to form the second tungsten seed layer. The flow rate can be selected according to actual needs. A small flow rate has good uniformity and a long reaction time, while a large flow rate has poor uniformity and a short reaction time. In some embodiments, the second tungsten seed layer is formed by atomic vapor deposition or chemical vapor deposition. In atomic vapor deposition, the borane gas and the second gas are introduced in sequence for 2 to 10 pulse cycles. Among them, the borane gas introduction time is 1 to 5 seconds, preferably 2 to 3 seconds; the WF6 gas introduction time is 0.2 to 1 second, preferably 0.2 to 0.5 seconds. B2H6 and WF6 are introduced separately, and the order is B2H6 first, then purge with inert gas, such as argon (Ar) for 3-5s, then introduce WF6, and then purge with Ar for 3-5s, which is one cycle.

[0100] In some embodiments, the flow rate of the third gas is 30-300 sccm, and the flow rate of the hydrogen gas is 200-20000 sccm. Hydrogen (H2) as a reducing agent does not introduce impurities, and can ensure that the tungsten (W) metal generated by the reaction has high purity and low resistance.

[0101] In some embodiments, before the above pretreatment, the temperature of the reaction chamber is first set to 280-400°C, and the pressure is adjusted to 40-300 torr, and then the subsequent chemical vapor deposition or atomic vapor deposition steps are performed. The deposition temperature of the first tungsten seed layer and the second tungsten seed layer is preferably 300°C, and the pressure is preferably 40 torr.

[0102] In some embodiments, the material of the dielectric layer includes but is not limited to silicon dioxide, and the material of the substrate includes but is not limited to one or more of aluminum, copper, titanium nitride, cobalt silicide and silicon.

[0103] In some embodiments, the material of the substrate is selected from one or more of aluminum, copper, titanium nitride, cobalt silicide and silicon. The semiconductor structure forming method of the present invention has a wide range of applications. By selecting different substrates, it can be used to solve the problem of poor adhesion of tungsten metal layers formed by depositing B2H6 as a precursor in different structures, such as buried word lines, gate structures, semiconductor layer interconnection contact structures (contact, via), etc.

[0104] The present invention also provides a semiconductor structure, comprising:

[0105] substrate;

[0106] a dielectric layer formed on the substrate;

[0107] a trench formed in the dielectric layer;

[0108] A barrier layer formed on the dielectric layer and the surface of the groove;

[0109] a diffusion barrier layer formed on the barrier layer;

[0110] a first tungsten seed layer formed on the diffusion barrier layer;

[0111] a second tungsten seed layer formed on the first tungsten seed layer;

[0112] A metal tungsten block is formed on the second tungsten seed layer;

[0113] The first tungsten seed layer does not contain boron, and the second tungsten seed layer contains boron.

[0114] In some embodiments, the diffusion barrier layer has a thickness of 0.1-5 nm; the first tungsten seed layer has a thickness of 0.1-5 nm; the second tungsten seed layer has a thickness of 2-10 nm. In some embodiments, the diffusion barrier layer is a silicon atomic layer.

[0115] In some embodiments, the barrier layer is a titanium nitride layer, a mixed layer of titanium nitride and titanium, or a tungsten nitride layer.

[0116] The semiconductor structure provided by the present invention has a diffusion barrier layer, so that the metal tungsten layer composed of the first tungsten seed layer, the second tungsten seed layer and the metal tungsten block has the advantages of low resistivity and strong adhesion. After the subsequent CMP process, the tungsten metal layer in the semiconductor structure further formed, such as the gate, tungsten plug structure, etc., is not easy to be peeled off, and the defects are few, thereby the product yield is high.

[0117] Those skilled in the art should note that the embodiments described in the present invention are merely exemplary, and various other substitutions, changes and improvements may be made within the scope of the present invention. Therefore, the present invention is not limited to the above embodiments, but only to the claims.

Claims

1. A method for forming a semiconductor structure, comprising: providing a substrate; forming a dielectric layer on the substrate, wherein the dielectric layer has a groove; forming a barrier layer on the dielectric layer and the surface of the trench; Passing silane gas to pre-treat the surface of the barrier layer to form a diffusion barrier layer, wherein the diffusion barrier layer is a silicon atomic layer; Introducing a first gas onto the silicon atomic layer to cause a deposition reaction to form a first tungsten seed layer; introducing a second gas and a borane gas onto the first tungsten seed layer to form a second tungsten seed layer by a deposition reaction; and Introducing a third gas and hydrogen gas onto the second tungsten seed layer to form a metal tungsten bulk material by deposition reaction; Wherein, the first tungsten seed layer does not contain boron, the second tungsten seed layer contains boron, and the deposition is chemical vapor deposition or atomic vapor deposition; The second tungsten seed layer is formed by atomic vapor deposition, and the borane gas and the second gas are sequentially introduced for 2 to 10 pulse cycles, and one pulse cycle includes: after introducing the borane gas for 1 to 5 seconds, an inert gas purge is performed for 3 to 5 seconds; after introducing the second gas for 0.2 to 1 second, an inert gas purge is performed for 2 to 5 seconds; The first gas, the second gas and the third gas are all tungsten hexafluoride.

2. The forming method according to claim 1, characterized in that: The silane gas is introduced at a flow rate of 30-300 sccm for reaction for 2-10 seconds to form the silicon atomic layer.

3. The forming method according to claim 1, characterized in that: The first gas is introduced at a flow rate of 30-300 sccm for reaction for 0.1-10 seconds to form the first tungsten seed layer.

4. The forming method according to claim 1, characterized in that: The second gas is introduced at a flow rate of 30-300 sccm, and the borane gas is introduced at a flow rate of 30-300 sccm to form the second tungsten seed layer.

5. The forming method according to claim 1, characterized in that: The flow rate of the third gas is 30-300 sccm, and the flow rate of the hydrogen gas is 200-20000 sccm.

6. The forming method according to claim 1, characterized in that: The chemical vapor deposition or atomic vapor deposition is performed at a temperature of 280-400° C. and a pressure of 40-300 torr.

7. The forming method according to claim 1, characterized in that: The thickness of the diffusion barrier layer is 0.1-5 nm, the thickness of the first tungsten seed layer is 0.1-5 nm, and the thickness of the second tungsten seed layer is 2-10 nm.

8. The forming method according to claim 1, characterized in that: The barrier layer is a titanium nitride layer, a mixed layer of titanium nitride and titanium, or a tungsten nitride layer.

9. The forming method according to claim 1, characterized in that: The material of the dielectric layer is silicon dioxide, and the material of the substrate is selected from one or more of aluminum, copper, titanium nitride, cobalt silicide and silicon.

10. A semiconductor structure, prepared by the method according to claim 1, comprising: substrate; a dielectric layer formed on the substrate; a trench formed in the dielectric layer; A barrier layer formed on the dielectric layer and the surface of the groove; a diffusion barrier layer formed on the barrier layer; a first tungsten seed layer formed on the diffusion barrier layer; a second tungsten seed layer formed on the first tungsten seed layer; A metal tungsten block is formed on the second tungsten seed layer, and the metal tungsten block fills the groove; The first tungsten seed layer, the second tungsten seed layer and the metal tungsten bulk material together constitute a metal tungsten layer, and the thickness of the metal tungsten layer is 10-100 nm; The first tungsten seed layer does not contain boron, and the second tungsten seed layer contains boron.

11. The semiconductor structure according to claim 10, characterized in that: The thickness of the diffusion barrier layer is 0.1-5 nm; the thickness of the first tungsten seed layer is 0.1-5 nm; and the thickness of the second tungsten seed layer is 2-10 nm.

12. The semiconductor structure according to claim 10, characterized in that The diffusion barrier layer is a silicon atomic layer.

13. The semiconductor structure according to claim 10, characterized in that: The barrier layer is a titanium nitride layer, a mixed layer of titanium nitride and titanium, or a tungsten nitride layer.

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