A method for preparing a tungsten plug

Abstract

The present invention relates to a method for preparing a tungsten plug, which belongs to the field of semiconductor manufacturing, and comprises: providing a substrate containing a contact hole; sequentially performing adhesion layer deposition and barrier layer deposition on the surface of the contact hole, and then sequentially performing tungsten mixed layer deposition, tungsten body layer deposition and removal operations to form a tungsten plug; wherein the tungsten mixed layer deposition comprises sequentially performing tungsten layer deposition and boron tungsten silicon layer deposition, the flow ratio of tungsten hexafluoride and silane in the tungsten layer deposition is (3-4):1, the flow ratio of borane and silane in the boron tungsten silicon layer deposition is (0.3-0.8):1, and the thickness of the tungsten layer obtained by the tungsten layer deposition is greater than the thickness of the boron tungsten silicon layer obtained by the boron tungsten silicon layer deposition. The preparation method provided by the present invention controls the deposition process parameters for forming the tungsten mixed layer, so that the tungsten layer obtained when the tungsten body layer is subsequently deposited in the contact hole has a good step coverage, avoids the formation of holes, gaps and other defects inside the tungsten plug, and is conducive to ensuring that the inside of the tungsten plug has good compactness.

Description

Technical Field

[0001] The invention relates to the field of semiconductor manufacturing, and in particular to a method for preparing a tungsten plug. Background Art

[0002] At present, in order to provide a larger area of ​​interconnection, the CMOS integrated circuit process introduces a more flexible multi-layer metal process. The most difficult problem in multi-layer metallization is to ensure the electrical continuity at the contact holes and through holes. The step coverage of sputtered aluminum decreases sharply as the aspect ratio of the hole increases. In the submicron design rules, the step coverage of contact holes and through holes must not be less than 20%, and the connection between each layer of metal relies on vertical interconnection-through hole plugs. The connection between each pole of MOS and the metal is realized by vertical contact hole plugs. The submicron standard process currently widely used in the industry is tungsten plug technology, which has both reliability and practicality.

[0003] For example, CN113629004A discloses a method for forming a tungsten contact plug, comprising: providing a substrate having a conductor and a dielectric layer thereon; forming a contact hole in the dielectric layer to at least partially expose the conductor; forming a barrier layer on the inner surface of the contact hole; performing an atomic layer deposition (ALD) process to deposit a tungsten seed layer on the barrier layer; and depositing a tungsten body layer to fill the contact hole to form the tungsten contact plug.

[0004] However, currently when forming tungsten contact plugs, there is still a defect of poor density inside the tungsten plug, that is, there are defects such as gaps or holes inside the tungsten plug, and ensuring good step coverage inside the tungsten plug is crucial to improving the stability and yield of the device. Summary of the invention

[0005] In view of the problems existing in the prior art, the object of the present invention is to provide a method for preparing a tungsten plug to solve the defects of the prior art such as the presence of voids or holes inside the tungsten plug.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for preparing a tungsten plug, the method comprising:

[0008] Providing a substrate with a contact hole; depositing an adhesion layer and a barrier layer on the surface of the contact hole in sequence, and then depositing a tungsten mixed layer, depositing a tungsten body layer and removing the layer in sequence to form a tungsten plug;

[0009] The tungsten mixed layer deposition includes a tungsten layer deposition and a boron tungsten silicon layer deposition carried out in sequence, the flow ratio of tungsten hexafluoride and silane in the tungsten layer deposition is (3-4):1, the flow ratio of borane and silane in the boron tungsten silicon layer deposition is (0.3-0.8):1, and the thickness of the tungsten layer obtained by the tungsten layer deposition is greater than the thickness of the boron tungsten silicon layer obtained by the boron tungsten silicon layer deposition.

[0010] The preparation method provided by the present invention controls the deposition process parameters for forming the tungsten mixed layer so that the tungsten layer obtained when the tungsten body layer is subsequently deposited in the contact hole has good step coverage, thereby avoiding the formation of defects such as holes and gaps inside the tungsten plug, which is beneficial to ensuring that the inside of the tungsten plug has good compactness, thereby improving the stability of the device.

[0011] As a preferred technical solution of the present invention, the adhesion layer obtained by deposition of the adhesion layer comprises a titanium layer. Preferably, the adhesion layer is deposited by chemical vapor deposition. Preferably, the thickness of the adhesion layer obtained by deposition of the adhesion layer is 5-6 nm.

[0012] As a preferred technical solution of the present invention, the barrier layer obtained by depositing the barrier layer comprises a titanium nitride layer. Preferably, the barrier layer is deposited by chemical vapor deposition. Preferably, the barrier layer obtained by depositing the barrier layer has a thickness of 10-15 nm.

[0013] As a preferred technical solution of the present invention, the tungsten layer is deposited by chemical vapor deposition. Preferably, the flow rate of tungsten hexafluoride in the tungsten layer deposition is 20-40 sccm.

[0014] As a preferred technical solution of the present invention, the temperature of the tungsten layer deposition is 400-600° C. Preferably, the thickness of the tungsten layer obtained by the deposition of the tungsten layer is 1-5 nm.

[0015] As a preferred technical solution of the present invention, the boron tungsten silicon layer is deposited by chemical vapor deposition. Preferably, the flow rate of borane in the boron tungsten silicon layer is 10-20 sccm. Preferably, the flow rate of tungsten hexafluoride in the boron tungsten silicon layer is 20-40 sccm.

[0016] As a preferred technical solution of the present invention, the temperature for depositing the boron tungsten silicon layer is 400-600° C. Preferably, the thickness of the boron tungsten silicon layer obtained by depositing the boron tungsten silicon layer is 0.2-0.6 nm.

[0017] As a preferred technical solution of the present invention, the tungsten body layer is deposited by chemical vapor deposition. Preferably, the tungsten body layer is deposited in a single continuous deposition process.

[0018] As a preferred technical solution of the present invention, the flow rate of tungsten hexafluoride in the tungsten bulk layer deposition is 40-50sccm. Preferably, the flow rate of hydrogen in the tungsten bulk layer deposition is 600-1500sccm. Preferably, the thickness of the tungsten layer obtained by the tungsten bulk layer deposition is 60-400nm.

[0019] As a preferred technical solution of the present invention, the temperature for depositing the tungsten body layer is 400-600°C.

[0020] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0021] The preparation method provided by the present invention realizes the preparation of a high-density tungsten plug by designing the preparation process of the tungsten plug and utilizing the coordination effect between each step. Specifically, a tungsten mixed layer is formed between the deposited tungsten layers to ensure that the corresponding deposition surface has a low adhesion coefficient when the tungsten body layer is deposited, thereby achieving reasonable closure of the tungsten body layer growth process in the contact hole, avoiding defects such as cracks caused by excessive local closure, ensuring good step coverage in the preparation of the tungsten plug, and reducing the contact resistance of the tungsten plug. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a SEM photograph of the tungsten plug obtained in Example 1 of the present invention; Figure 2 This is a SEM photograph of the tungsten plug obtained in Comparative Example 7 of the present invention.

[0023] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0024] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0025] This embodiment provides a method for preparing a tungsten plug, the method comprising:

[0026] Providing a substrate with a contact hole; depositing an adhesion layer and a barrier layer on the surface of the contact hole in sequence, and then sequentially depositing a tungsten mixed layer, depositing a tungsten body layer and removing the layer to form a tungsten plug;

[0027] The tungsten mixed layer deposition includes a tungsten layer deposition and a boron tungsten silicon layer deposition carried out in sequence, the flow ratio of tungsten hexafluoride and silane in the tungsten layer deposition is (3-4):1, the flow ratio of borane and silane in the boron tungsten silicon layer deposition is (0.3-0.8):1, and the thickness of the tungsten layer obtained by the tungsten layer deposition is greater than the thickness of the boron tungsten silicon layer obtained by the boron tungsten silicon layer deposition.

[0028] In the present invention, the aspect ratio of the contact hole (depth of the contact hole / width or diameter of the contact hole) is ≥4.

[0029] In the present invention, the flow ratio of tungsten hexafluoride and silane in the deposition of the tungsten layer is (3-4):1, for example, it can be 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1 or 4:1, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0030] In the present invention, the flow ratio of borane and silane in the deposition of the boron tungsten silicon layer is (0.3-0.8):1, for example, it can be 0.3:1, 0.35:1, 0.4:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, 0.65:1, 0.7:1, 0.75:1 or 0.8:1, etc., but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0031] Among them, the adhesion layer obtained by depositing the adhesion layer includes a titanium layer, and the method of depositing the adhesion layer includes chemical vapor deposition. The thickness of the adhesion layer obtained by depositing the adhesion layer is 5-6nm, for example, it can be 5nm, 5.2nm, 5.4nm, 5.6nm, 5.8nm or 6nm, etc., but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0032] Among them, the barrier layer obtained by depositing the barrier layer includes a titanium nitride layer, and the barrier layer is deposited in a manner including chemical vapor deposition. The thickness of the barrier layer obtained by depositing the barrier layer is 10-15nm, for example, it can be 10nm, 11nm, 12nm, 13nm, 14nm or 15nm, etc., but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0033] The thickness of the tungsten layer obtained by depositing the tungsten layer is 1-5 nm, for example, 1 nm, 2 nm, 3 nm, 4 nm or 5 nm, but is not limited to the listed values, and other values ​​not listed in the range also meet the requirements. The method of depositing the tungsten layer includes chemical vapor deposition.

[0034] The flow rate of tungsten hexafluoride in the deposition of the tungsten layer is 20-40 sccm, for example, it can be 20 sccm, 22 sccm, 24 sccm, 26 sccm, 28 sccm, 30 sccm, 32 sccm, 34 sccm, 36 sccm, 38 sccm or 40 sccm, but it is not limited to the listed values, and other values ​​not listed in this range also meet the requirements. The temperature of the deposition of the tungsten layer is 400-600°C, for example, it can be 400°C, 420°C, 440°C, 460°C, 480°C, 500°C, 520°C, 540°C, 560°C, 580°C or 600°C, but it is not limited to the listed values, and other values ​​not listed in this range also meet the requirements.

[0035] The thickness of the boron tungsten silicon layer obtained by depositing the boron tungsten silicon layer is 0.2-0.6 nm, for example, 0.2 nm, 0.25 nm, 0.3 nm, 0.35 nm, 0.4 nm, 0.45 nm, 0.5 nm, 0.55 nm or 0.6 nm, but is not limited to the listed values, and other values ​​not listed in the range also meet the requirements. The boron tungsten silicon layer is deposited by chemical vapor deposition.

[0036] Wherein, the flow rate of borane in the boron tungsten silicon layer deposition is 10-20sccm, for example, it can be 10sccm, 11sccm, 12sccm, 13sccm, 14sccm, 15sccm, 16sccm, 17sccm, 18sccm, 19sccm or 20sccm, etc., but it is not limited to the listed values, and other values ​​not listed in this range also meet the requirements. The flow rate of tungsten hexafluoride in the boron tungsten silicon layer deposition is 20-40sccm, for example, it can be 20sccm, 22sccm, 24sccm, 26sccm, 28sccm, 30sccm, 32sccm, 34sccm, 36sccm, 38sccm or 40sccm, etc., but it is not limited to the listed values, and other values ​​not listed in this range also meet the requirements. The deposition temperature of the boron tungsten silicon layer is 400-600°C, for example, it can be 400°C, 420°C, 440°C, 460°C, 480°C, 500°C, 520°C, 540°C, 560°C, 580°C or 600°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0037] The thickness of the tungsten layer obtained by the tungsten body layer deposition is 60-400nm, for example, it can be 60nm, 70nm, 80nm, 90nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm or 400nm, but is not limited to the listed values, and other values ​​not listed in the range also meet the requirements. The tungsten body layer deposition method includes chemical vapor deposition. The tungsten body layer deposition is a single continuous deposition process.

[0038] Wherein, the flow rate of tungsten hexafluoride in the tungsten bulk layer deposition is 40-50sccm, for example, it can be 40sccm, 41sccm, 42sccm, 43sccm, 44sccm, 45sccm, 46sccm, 47sccm, 48sccm, 49sccm or 50sccm, etc., but it is not limited to the listed values, and other values ​​not listed in this range also meet the requirements. The flow rate of hydrogen in the tungsten bulk layer deposition is 600-1500sccm, for example, it can be 600sccm, 700sccm, 800sccm, 900sccm, 1000sccm, 1100sccm, 1200sccm, 1300sccm, 1400sccm or 1400sccm, etc., but it is not limited to the listed values, and other values ​​not listed in this range also meet the requirements. The deposition temperature of the tungsten body layer is 400-600°C, for example, it can be 400°C, 420°C, 440°C, 460°C, 480°C, 500°C, 520°C, 540°C, 560°C, 580°C or 600°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0039] In the present invention, the carrier gas used in the vapor deposition process includes one or at least two of nitrogen, argon, helium or neon, etc., which are commonly used carrier gases in the art.

[0040] In the present invention, the removal operation performed after the deposition of the tungsten body layer is to remove the excess tungsten material in the tungsten body layer to form a tungsten plug. The specific removal method can be mechanical chemical grinding, vapor etching, etc. to achieve the removal of excess material.

[0041] Furthermore, during the deposition of the corresponding layers, the deposition area may be selected to be larger than the surface of the contact hole, thereby ensuring that the surface of the contact hole can be fully deposited, thereby ensuring the deposition effect.

[0042] In the present invention, when the deposition process of each layer is carried out, the parameters defined in the present invention can be selected specifically according to the conventional requirements in the art to ensure that the defined requirements of the present invention for each layer can be achieved.

[0043] Example 1

[0044] This embodiment provides a method for preparing a tungsten plug, the method comprising:

[0045] A substrate with a contact hole is provided; adhesion layer deposition and barrier layer deposition are sequentially performed on the surface of the contact hole, and then a tungsten mixed layer deposition, a tungsten body layer deposition and removal operation are sequentially performed to form a tungsten plug.

[0046] The adhesion layer deposited is a titanium layer, the adhesion layer is deposited by chemical vapor deposition, and the thickness of the adhesion layer deposited is 5.8 nm. The barrier layer deposited is a titanium nitride layer, the barrier layer is deposited by chemical vapor deposition, and the thickness of the barrier layer deposited is 13 nm.

[0047] The tungsten mixed layer deposition includes sequential deposition of a tungsten layer and deposition of a boron tungsten silicon layer. The thickness of the tungsten layer obtained by the deposition of the tungsten layer is greater than the thickness of the boron tungsten silicon layer obtained by the deposition of the boron tungsten silicon layer. The thickness of the tungsten layer obtained by the deposition of the tungsten layer is 2 nm. The tungsten layer is deposited by chemical vapor deposition. The flow rate of tungsten hexafluoride in the deposition of the tungsten layer is 35 sccm. The flow rate ratio of tungsten hexafluoride to silane in the deposition of the tungsten layer is 3.2:1. The temperature of the tungsten layer deposition is 550°C. The thickness of the boron tungsten silicon layer obtained by the deposition of the boron tungsten silicon layer is 0.3 nm. The boron tungsten silicon layer is deposited by chemical vapor deposition. The flow rate ratio of borane to silane in the deposition of the boron tungsten silicon layer is 0.5:1. The flow rate of borane in the deposition of the boron tungsten silicon layer is 18 sccm. The flow rate of tungsten hexafluoride in the deposition of the boron tungsten silicon layer is 30 sccm. The temperature of the boron tungsten silicon layer deposition is 550°C.

[0048] The tungsten bulk layer is deposited by chemical vapor deposition, and the tungsten bulk layer deposition is a single continuous deposition process. The flow rate of tungsten hexafluoride in the tungsten bulk layer deposition is 48 sccm, the flow rate of hydrogen in the tungsten bulk layer deposition is 1200 sccm, the thickness of the tungsten layer obtained by the tungsten bulk layer deposition is 200 nm, and the temperature of the tungsten bulk layer deposition is 550°C.

[0049] The cross-section SEM test of the product after tungsten layer deposition is carried out. The test results are as follows: Figure 1 As shown in the figure, it can be seen that the obtained tungsten plug has good density.

[0050] Example 2

[0051] This embodiment provides a method for preparing a tungsten plug, the method comprising:

[0052] A substrate with a contact hole is provided; adhesion layer deposition and barrier layer deposition are sequentially performed on the surface of the contact hole, and then a tungsten mixed layer deposition, a tungsten body layer deposition and removal operation are sequentially performed to form a tungsten plug.

[0053] The adhesion layer deposited is a titanium layer, the adhesion layer is deposited by chemical vapor deposition, and the thickness of the adhesion layer deposited is 5.5 nm. The barrier layer deposited is a titanium nitride layer, the barrier layer is deposited by chemical vapor deposition, and the thickness of the barrier layer deposited is 12 nm.

[0054] The tungsten mixed layer deposition includes sequential deposition of a tungsten layer and deposition of a boron tungsten silicon layer. The thickness of the tungsten layer obtained by the deposition of the tungsten layer is greater than the thickness of the boron tungsten silicon layer obtained by the deposition of the boron tungsten silicon layer. The thickness of the tungsten layer obtained by the deposition of the tungsten layer is 3nm. The tungsten layer is deposited by chemical vapor deposition. The flow rate of tungsten hexafluoride in the deposition of the tungsten layer is 30sccm. The flow rate ratio of tungsten hexafluoride to silane in the deposition of the tungsten layer is 3.5:1. The temperature of the tungsten layer deposition is 500°C. The thickness of the boron tungsten silicon layer obtained by the deposition of the boron tungsten silicon layer is 0.5nm. The boron tungsten silicon layer is deposited by chemical vapor deposition. The flow rate ratio of borane to silane in the deposition of the boron tungsten silicon layer is 0.4:1. The flow rate of borane in the deposition of the boron tungsten silicon layer is 14sccm. The flow rate of tungsten hexafluoride in the deposition of the boron tungsten silicon layer is 35sccm. The temperature of the boron tungsten silicon layer deposition is 500°C.

[0055] The tungsten bulk layer is deposited by chemical vapor deposition, which is a single continuous deposition process. The flow rate of tungsten hexafluoride in the tungsten bulk layer deposition is 45 sccm, the flow rate of hydrogen in the tungsten bulk layer deposition is 900 sccm, the thickness of the tungsten layer obtained by the tungsten bulk layer deposition is 150 nm, and the temperature of the tungsten bulk layer deposition is 500°C.

[0056] Example 3

[0057] This embodiment provides a method for preparing a tungsten plug, the method comprising:

[0058] A substrate with a contact hole is provided; adhesion layer deposition and barrier layer deposition are sequentially performed on the surface of the contact hole, and then a tungsten mixed layer deposition, a tungsten body layer deposition and removal operation are sequentially performed to form a tungsten plug.

[0059] The adhesion layer deposited is a titanium layer, the adhesion layer is deposited by chemical vapor deposition, and the thickness of the adhesion layer deposited is 6 nm. The barrier layer deposited is a titanium nitride layer, the barrier layer is deposited by chemical vapor deposition, and the thickness of the barrier layer deposited is 15 nm.

[0060] The tungsten mixed layer deposition includes sequential deposition of a tungsten layer and deposition of a boron tungsten silicon layer. The thickness of the tungsten layer obtained by the deposition of the tungsten layer is greater than the thickness of the boron tungsten silicon layer obtained by the deposition of the boron tungsten silicon layer. The thickness of the tungsten layer obtained by the deposition of the tungsten layer is 5 nm. The tungsten layer is deposited by chemical vapor deposition. The flow rate of tungsten hexafluoride in the deposition of the tungsten layer is 40 sccm. The flow rate ratio of tungsten hexafluoride to silane in the deposition of the tungsten layer is 4:1. The temperature of the tungsten layer deposition is 600°C. The thickness of the boron tungsten silicon layer obtained by the deposition of the boron tungsten silicon layer is 0.6 nm. The boron tungsten silicon layer is deposited by chemical vapor deposition. The flow rate ratio of borane to silane in the deposition of the boron tungsten silicon layer is 0.8:1. The flow rate of borane in the deposition of the boron tungsten silicon layer is 10 sccm. The flow rate of tungsten hexafluoride in the deposition of the boron tungsten silicon layer is 20 sccm. The temperature of the boron tungsten silicon layer deposition is 600°C.

[0061] The tungsten bulk layer is deposited by chemical vapor deposition, which is a single continuous deposition process. The flow rate of tungsten hexafluoride in the tungsten bulk layer deposition is 50 sccm, the flow rate of hydrogen in the tungsten bulk layer deposition is 1500 sccm, the thickness of the tungsten layer obtained by the tungsten bulk layer deposition is 400 nm, and the temperature of the tungsten bulk layer deposition is 600°C.

[0062] Example 4

[0063] This embodiment provides a method for preparing a tungsten plug, the method comprising:

[0064] A substrate with a contact hole is provided; adhesion layer deposition and barrier layer deposition are sequentially performed on the surface of the contact hole, and then a tungsten mixed layer deposition, a tungsten body layer deposition and removal operation are sequentially performed to form a tungsten plug.

[0065] The adhesion layer deposited is a titanium layer, and the adhesion layer is deposited by chemical vapor deposition. The thickness of the adhesion layer deposited is 5nm. The barrier layer deposited is a titanium nitride layer, and the barrier layer is deposited by chemical vapor deposition. The thickness of the barrier layer deposited is 10nm.

[0066] The tungsten mixed layer deposition includes sequential deposition of a tungsten layer and deposition of a boron tungsten silicon layer. The thickness of the tungsten layer obtained by the deposition of the tungsten layer is greater than the thickness of the boron tungsten silicon layer obtained by the deposition of the boron tungsten silicon layer. The thickness of the tungsten layer obtained by the deposition of the tungsten layer is 1 nm. The tungsten layer is deposited by chemical vapor deposition. The flow rate of tungsten hexafluoride in the deposition of the tungsten layer is 20 sccm. The flow rate ratio of tungsten hexafluoride to silane in the deposition of the tungsten layer is 3:1. The temperature of the tungsten layer deposition is 400°C. The thickness of the boron tungsten silicon layer obtained by the deposition of the boron tungsten silicon layer is 0.2 nm. The boron tungsten silicon layer is deposited by chemical vapor deposition. The flow rate ratio of borane to silane in the deposition of the boron tungsten silicon layer is 0.3:1. The flow rate of borane in the deposition of the boron tungsten silicon layer is 20 sccm. The flow rate of tungsten hexafluoride in the deposition of the boron tungsten silicon layer is 40 sccm. The temperature of the boron tungsten silicon layer deposition is 400°C.

[0067] The tungsten bulk layer is deposited by chemical vapor deposition, which is a single continuous deposition process. The flow rate of tungsten hexafluoride in the tungsten bulk layer deposition is 40 sccm, the flow rate of hydrogen in the tungsten bulk layer deposition is 600 sccm, the thickness of the tungsten layer obtained by the tungsten bulk layer deposition is 60 nm, and the temperature of the tungsten bulk layer deposition is 400°C.

[0068] Example 5

[0069] The only difference from Example 1 is that the flow rate of tungsten hexafluoride during the deposition of the tungsten layer is 100 sccm.

[0070] Example 6

[0071] The only difference from Example 1 is that the flow rate of tungsten hexafluoride during the deposition of the tungsten layer is 10 sccm.

[0072] Example 7

[0073] The only difference from Example 1 is that the flow rate of borane during the deposition of the boron tungsten silicon layer is 5 sccm.

[0074] Example 8

[0075] The only difference from Example 1 is that the flow rate of borane in the deposition of the boron tungsten silicon layer is 30 sccm.

[0076] Example 9

[0077] The only difference from Example 1 is that the flow rate of tungsten hexafluoride in the deposition of the boron tungsten silicon layer is 10 sccm.

[0078] Example 10

[0079] The only difference from Example 1 is that the flow rate of tungsten hexafluoride in the deposition of the boron tungsten silicon layer is 50 sccm.

[0080] Comparative Example 1

[0081] The only difference from Example 1 is that the flow ratio of tungsten hexafluoride and silane in the deposition of the tungsten layer is 1:1.

[0082] Comparative Example 2

[0083] The only difference from Example 1 is that the flow ratio of tungsten hexafluoride to silane in the deposition of the tungsten layer is 1:3.

[0084] Comparative Example 3

[0085] The only difference from Example 1 is that no tungsten layer deposition is performed.

[0086] Comparative Example 4

[0087] The only difference from Example 1 is that the boron tungsten silicon layer deposition is not performed.

[0088] Comparative Example 5

[0089] The only difference from Example 1 is that the flow ratio of borane to silane in the deposition of the boron tungsten silicon layer is 2:1.

[0090] Comparative Example 6

[0091] The only difference from Example 1 is that the flow ratio of borane to silane in the deposition of the boron tungsten silicon layer is 1:4.

[0092] Comparative Example 7

[0093] The only difference from Example 1 is that the thickness of the tungsten layer obtained by depositing the tungsten layer is 0.3 nm, and the thickness of the boron tungsten silicon layer obtained by depositing the boron tungsten silicon layer is 2 nm; the SEM photo of the obtained tungsten plug is as follows: Figure 2 As shown in the figure, it can be seen that the step coverage of the obtained tungsten plug is poor and there are pore defects inside the tungsten plug.

[0094] The tungsten plugs obtained in the embodiment and the comparative example were subjected to step coverage detection and analysis by means of SEM, including bottom step coverage and sidewall step coverage, wherein bottom step coverage = thickness of bottom deposition of contact hole / thickness of plane deposition, sidewall step coverage = overhang thickness / thickness of plane deposition, and the detection results are detailed in Table 1.

[0095] Table 1

[0096]

[0097] As can be seen from Table 1, in the solution provided by the present invention, the preparation method provided by the present invention controls the deposition process parameters for forming the tungsten mixed layer so that the tungsten layer obtained when the tungsten body layer is subsequently deposited in the contact hole has good step coverage, thereby avoiding the formation of defects such as holes and gaps inside the tungsten plug, which is beneficial to ensuring that the inside of the tungsten plug has good compactness, that is, has good step coverage, thereby improving the stability of the device.

[0098] It is stated that the present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0099] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0100] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0101] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing a tungsten plug, characterized in that: The preparation method comprises: providing a substrate having a contact hole; Adhesion layer deposition and barrier layer deposition are sequentially performed on the contact hole surface, and then tungsten mixed layer deposition, tungsten body layer deposition and removal operations are sequentially performed to form a tungsten plug; The tungsten mixed layer deposition includes sequentially depositing a tungsten layer and depositing a boron tungsten silicon layer; The flow ratio of tungsten hexafluoride and silane in the tungsten layer deposition is (3-4):1; The flow ratio of borane to silane in the boron tungsten silicon layer deposition is (0.3-0.8):1; The thickness of the tungsten layer obtained by depositing the tungsten layer is greater than the thickness of the boron tungsten silicon layer obtained by depositing the boron tungsten silicon layer.

2. The preparation method according to claim 1, characterized in that: The adhesion layer deposited and obtained includes a titanium layer; The adhesion layer is deposited in a manner including chemical vapor deposition; The thickness of the adhesion layer obtained by depositing the adhesion layer is 5-6 nm.

3. The preparation method according to claim 1, characterized in that: The barrier layer deposited by the barrier layer comprises a titanium nitride layer; The barrier layer is deposited in a manner including chemical vapor deposition; The thickness of the barrier layer obtained by depositing the barrier layer is 10-15 nm.

4. The preparation method according to claim 1, characterized in that: The tungsten layer is deposited in a manner including chemical vapor deposition; The flow rate of tungsten hexafluoride during the deposition of the tungsten layer is 20-40 sccm.

5. The preparation method according to claim 1, characterized in that: The temperature of the tungsten layer deposition is 400-600°C; The thickness of the tungsten layer obtained by depositing the tungsten layer is 1-5 nm.

6. The preparation method according to claim 1, characterized in that: The boron tungsten silicon layer is deposited in a manner including chemical vapor deposition; The flow rate of borane in the boron tungsten silicon layer deposition is 10-20 sccm; The flow rate of tungsten hexafluoride in the boron tungsten silicon layer deposition is 20-40 sccm.

7. The preparation method according to claim 1, characterized in that: The temperature of depositing the boron tungsten silicon layer is 400-600°C; The thickness of the boron tungsten silicon layer obtained by depositing the boron tungsten silicon layer is 0.2-0.6 nm.

8. The preparation method according to claim 1, characterized in that: The method of depositing the tungsten body layer includes chemical vapor deposition; The tungsten bulk layer deposition is a single continuous deposition process.

9. The preparation method according to claim 1, characterized in that: The flow rate of tungsten hexafluoride in the tungsten bulk layer deposition is 40-50 sccm; The flow rate of hydrogen in the tungsten bulk layer deposition is 600-1500 sccm; The thickness of the tungsten layer obtained by depositing the tungsten body layer is 60-400 nm.

10. The preparation method according to claim 1, characterized in that: The temperature of depositing the tungsten body layer is 400-600°C.

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