Process method for depositing tungsten plug and semiconductor device
By alternately passing fluorine-containing tungsten gas and hydrogen-containing gas into the semiconductor device to form a fluorine-containing tungsten film, preventing fluorine atoms from attacking the substrate, the fluorine atom penetration problem in the traditional tungsten plug process is solved and the yield of semiconductor devices is improved.
Patent Information
- Application Number
- CN202310788587.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-30
- Publication Date
- 2024-12-31
AI Technical Summary
In semiconductor devices, fluorine atoms penetrate the substrate due to the thinning of the barrier layer in the conventional tungsten plug process, resulting in problems of electrical failure and yield reduction.
By alternately passing fluorine-containing tungsten gas and hydrogen-containing gas on the preset substrate for atomic layer deposition reaction, a fluorine-containing tungsten film is formed, and the fluorine-containing tungsten film formed before the deposition of the bulk tungsten layer has a fluorine content of less than the bulk tungsten layer. Fluorine content, blocking fluorine atoms from attacking the substrate.
It effectively alleviates the problem of fluorine atoms penetrating the bottom substrate, avoids fluorine attack points inside the substrate, and improves the yield of semiconductor devices.
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Figure CN119230478A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor technology, and in particular to a process method for depositing a tungsten plug and a semiconductor device. Background Art
[0002] With the gradual development of integrated circuit technology, feature sizes are getting smaller and smaller. Traditional aluminum interconnection technology is limited by signal delay under small line width. In order to solve this problem, people use copper interconnection instead of aluminum interconnection technology. The emergence of copper interconnection technology has solved the problem of signal delay very well, and the integration of chips and the density of devices have also been greatly improved. However, due to the diffusion problem of copper, the contact hole process connecting the front-end device and the back-end interconnection line can use chemically and electrically stable metals to fill the holes (Via) or trenches (Trench), such as tungsten plug (W-plug) technology.
[0003] Tungsten has stable chemical and electrical properties. Tungsten plug (W-plug) is a process widely used in the contemporary semiconductor industry. It uses a unique method to fill metal tungsten into vias or trenches, and uses the good conductivity and anti-electromigration properties of metal tungsten to ultimately achieve the process requirements of reliable electrical conduction between front-end devices and back-end metal interconnects. In the related tungsten plug process, a barrier layer with the function of protecting the substrate is usually set between the substrate and the bulk tungsten layer. As the feature size becomes smaller and smaller, the barrier layer has an increasingly greater impact on the resistivity of the tungsten plug. The related tungsten plug process usually uses a method of thinning the thickness of the barrier layer and the nucleation layer to reduce the impact on the resistivity. However, the barrier layer after thinning has greatly weakened its barrier performance against fluorine atoms, and it is easy for fluorine atoms to penetrate the barrier and attack the bottom substrate, causing the electrical failure of semiconductor devices and reduced yield. Summary of the invention
[0004] In view of this, the purpose of the present invention is to provide a process method for depositing tungsten plugs and a semiconductor device, which can alleviate the problem of fluorine atoms penetrating the bottom substrate, avoid the occurrence of fluorine attack points inside the substrate that cause electrical failure of the semiconductor device, and improve the yield of the semiconductor device.
[0005] In order to achieve the above purpose, the technical solution adopted by the embodiment of the present invention is as follows:
[0006] In a first aspect, an embodiment of the present invention provides a process method for depositing a tungsten plug, which is used to process a preset substrate, wherein the preset substrate includes a substrate and a protective layer located above the substrate, and the process method for depositing the tungsten plug includes: alternately introducing fluorine-containing tungsten gas and hydrogen-containing gas into the reaction chamber for atomic layer deposition reaction to form a fluorine-containing tungsten film; simultaneously introducing the fluorine-containing tungsten gas and the hydrogen-containing gas into the reaction chamber for vapor deposition reaction to form a bulk tungsten layer; wherein the fluorine content of the fluorine-containing tungsten film is less than the fluorine content of the bulk tungsten layer.
[0007] Furthermore, an embodiment of the present invention provides a first possible implementation of the first aspect, wherein, before forming the fluorine-containing tungsten film, the process method for depositing the tungsten plug also includes: introducing a hydrogen-containing gas into the reaction chamber to allow the hydrogen-containing gas to adsorb on the surface of the protective layer to form a wetting layer; wherein the wetting layer produces a reduction reaction with fluorine, a by-product produced during the formation of the fluorine-containing tungsten film.
[0008] Furthermore, an embodiment of the present invention provides a second possible implementation of the first aspect, wherein the introducing of hydrogen-containing gas into the reaction chamber so that the hydrogen-containing gas is adsorbed on the surface of the protective layer to form a wetting layer comprises: stabilizing the pressure of the reaction chamber at a first preset pressure value, or increasing the pressure of the reaction chamber from a second preset pressure value to a third preset pressure value; continuously introducing hydrogen-containing gas at a first preset flow value into the reaction chamber so that hydrogen atoms are adsorbed on the surface of the protective layer to form the wetting layer.
[0009] Further, an embodiment of the present invention provides a third possible implementation of the first aspect, wherein the range of the first preset flow value is 1000sccm to 10000sccm; and / or the range of the first preset pressure value, the second preset pressure value and the third preset pressure value are all 5Torr-300Torr.
[0010] Further, an embodiment of the present invention provides a fourth possible implementation of the first aspect, wherein the alternate introduction of fluorine-containing tungsten gas and hydrogen-containing gas into the reaction chamber to perform an atomic layer deposition reaction to form a fluorine-containing tungsten film comprises: S500, heating the substrate, maintaining the temperature of the substrate within a first preset temperature range, and stabilizing the pressure of the reaction chamber within a fourth preset pressure range; S502, introducing the fluorine-containing tungsten gas into the reaction chamber, and the flow rate of the fluorine-containing tungsten gas is set at a second preset flow rate value, and the introduction time of the fluorine-containing tungsten gas is set to a first preset duration, so that the fluorine-containing metal molecules are adsorbed on the wetted substrate. layer surface; S504, performing a purge process, and the time of the purge process is set to a second preset time length to remove the fluorine-containing tungsten gas floating in the reaction chamber; S506, introducing the hydrogen-containing gas into the reaction chamber, and the flow rate of the hydrogen-containing gas is set to a third preset flow rate value, and the introduction time of the hydrogen-containing gas is set to a third preset time length, so that the hydrogen-containing gas and the fluorine-containing metal molecules undergo a reduction reaction to generate a fluorine-containing tungsten film; S508, performing a purge process, and the time of the purge process is set to a fourth preset time length to remove the hydrogen-containing gas in the reaction chamber and the hydrogen fluoride gas generated by the reduction reaction.
[0011] Furthermore, an embodiment of the present invention provides a fifth possible implementation of the first aspect, wherein the process method for depositing a tungsten plug further includes: cyclically executing S500 to S508 for a preset number of times to form the fluorine-containing tungsten film of a preset thickness.
[0012] Further, an embodiment of the present invention provides a sixth possible implementation of the first aspect, wherein the first preset temperature range is 250°C-400°C; and / or the fourth preset pressure range is 3Torr-100Torr; and / or the second preset flow value range is 10sccm-500sccm; and / or the third preset flow value range is 100sccm-10000sccm.
[0013] Further, an embodiment of the present invention provides a seventh possible implementation of the first aspect, wherein the range of the first preset time length, the second preset time length, the third preset time length and the fourth preset time length are all 0.1s-5s; and / or the range of the preset thickness is greater than 1nm.
[0014] In the second aspect, an embodiment of the present invention further provides a semiconductor device, comprising: a contact hole, a fluorine-containing tungsten film and a bulk tungsten layer deposited on a protective layer of a contact hole substrate, the fluorine-containing tungsten film and the bulk tungsten layer being deposited based on the process method for depositing a tungsten plug as described in any one of the first aspects, and the fluorine-containing tungsten film being located between the protective layer and the bulk tungsten layer.
[0015] Furthermore, an embodiment of the present invention provides a first possible implementation of the second aspect, wherein the protective layer includes a barrier layer and a nucleation layer, and the barrier layer is located between the substrate and the nucleation layer.
[0016] The embodiment of the present invention provides a tungsten plug deposition process method and a semiconductor device for processing a preset substrate, wherein the preset substrate includes a substrate and a protective layer located above the substrate, and the tungsten plug deposition process method includes: alternately introducing fluorine-containing tungsten gas and hydrogen-containing gas into a reaction chamber for atomic layer deposition reaction to form a fluorine-containing tungsten film; simultaneously introducing fluorine-containing tungsten gas and hydrogen-containing gas into the reaction chamber for vapor phase deposition reaction to form a bulk tungsten layer; wherein the fluorine content of the fluorine-containing tungsten film is less than the fluorine content of the bulk tungsten layer. The present invention can block a large number of byproduct fluorine atoms generated in the bulk tungsten layer formation stage from attacking the substrate by depositing a layer of fluorine-containing tungsten film before the bulk tungsten layer is deposited, and the fluorine impurity content in the fluorine-containing tungsten film is low, and the probability of attacking the substrate is low, which alleviates the problem of fluorine atoms penetrating the bottom substrate, avoids the occurrence of fluorine attack points inside the substrate that cause electrical failure of the semiconductor device, and improves the yield of the semiconductor device.
[0017] Other features and advantages of the embodiments of the present invention will be described in the following description, or some features and advantages can be inferred or determined without doubt from the description, or can be learned by implementing the above-mentioned techniques of the embodiments of the present invention.
[0018] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.
[0020] Figure 1 A related process flow chart of depositing tungsten plugs is shown;
[0021] Figure 2 shows the relevant vent timing diagram of the deposition tungsten plug process;
[0022] Figure 3 A schematic diagram of hole filling related to the tungsten plug process is shown;
[0023] Figure 4 A flow chart of a process for depositing a tungsten plug provided by an embodiment of the present invention is shown;
[0024] Figure 5 A process flow chart of depositing a tungsten plug provided by an embodiment of the present invention is shown;
[0025] Figure 6 Another process flow chart of depositing a tungsten plug provided by an embodiment of the present invention is shown;
[0026] Figure 7 A ventilation timing diagram of a process for depositing a tungsten plug provided by an embodiment of the present invention is shown;
[0027] Figure 8 A schematic diagram of hole filling provided by an embodiment of the present invention is shown. DETAILED DESCRIPTION
[0028] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution of the present invention will be described below in conjunction with the drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.
[0029] In the related deposition tungsten plug process, an adhesion barrier layer (Ti / TiN) is grown in advance before the tungsten plug is grown. TiN mainly plays the role of blocking fluorine atoms from attacking the bottom substrate. The growth of the tungsten plug is divided into two processes: the growth of the nucleation layer and the growth of the bulk tungsten layer. Figure 1 The process flow chart of the related tungsten plug deposition is shown, and the related tungsten plug deposition process mainly includes the following steps:
[0030] Step S101 : heating a wafer to a temperature required by a process, wherein the wafer includes a substrate 11 and a TiN barrier layer 12 .
[0031] Step S102: generating a nucleation layer 13 on the surface of the TiN barrier layer 12. By generating the nucleation layer 13, the growth incubation period of the bulk tungsten layer can be reduced.
[0032] Step S103 , forming a bulk tungsten layer 14 on the surface of the nucleation layer 13 .
[0033] See Figure 2 The ventilation timing diagram of the tungsten plug deposition process is shown. The ventilation timing of the tungsten plug deposition process can be performed according to the following steps:
[0034] S20: After the wafer is heated to a desired temperature, the growth of the nucleation layer begins.
[0035] The growth of the nucleation layer is carried out in the form of atomic layer deposition. B2H6 and WF6 are alternately introduced into the reaction chamber for atomic layer deposition (ALD) reaction. The steps of B2H6 and WF6 for atomic layer deposition reaction are cyclically performed. Each cycle includes the following four steps:
[0036] S21: introducing a B2H6 pulse of a set duration into the reaction chamber; S22: introducing an inert gas into the reaction chamber to purge the reaction chamber; S23: introducing a WF6 pulse of a set duration into the reaction chamber;
[0037] S24: Introduce an inert gas into the reaction chamber to purge the reaction chamber. The number of cycles of performing steps S21 to S24 can be determined according to the required thickness of the nucleation layer.
[0038] S25: After the nucleation layer is grown, WF6 pulse and H2 pulse are introduced into the reaction chamber at the same time to perform a chemical vapor deposition (CVD) reaction to generate a bulk tungsten layer. The process of generating the bulk tungsten layer is accompanied by the generation of by-product F atoms.
[0039] The above nucleation layer is a kind of amorphous tungsten with a large resistivity, and the bulk tungsten layer is a crystalline tungsten with a small resistivity. The resistivity of the TiN barrier layer and the tungsten nucleation layer is large. With the development of the process, the feature size is getting smaller and smaller, and the barrier layer and the tungsten nucleation layer have an increasing impact on the resistivity of the tungsten plug. The relevant tungsten plug process usually adopts the method of thinning the thickness of the barrier layer and the nucleation layer to reduce the impact on the resistivity. See, for example Figure 3 As shown in the schematic diagram of the hole filling process of the related tungsten plug, after the thickness of the barrier layer 12 and the nucleation layer 13 is reduced, the ability of the barrier layer 12 to block fluorine attack is easily weakened, and the byproduct fluorine atoms are generated in the process of chemical vapor deposition reaction of WF6 and H2 to generate the bulk tungsten layer 14. The generated byproduct F can easily penetrate the barrier layer 12 with reduced thickness and then attack the substrate 11, resulting in fluorine attack points 30, i.e., voids, inside the substrate 11. The appearance of the fluorine attack points 30 can easily cause the barrier layer 12 to break, which in turn can cause electrical failure of the semiconductor device and reduce the yield.
[0040] In order to improve the above problems, an embodiment of the present invention provides a tungsten plug deposition process method and a semiconductor device, and the embodiment of the present invention is described in detail below.
[0041] This embodiment provides a process method for depositing a tungsten plug, which can be used to process a preset substrate, see Figure 4 The process flow chart of depositing tungsten plug is shown, the method comprises the following steps:
[0042] In step S402 , fluorine-containing tungsten gas and hydrogen-containing gas are alternately introduced into the reaction chamber to perform an atomic layer deposition reaction to form a fluorine-containing tungsten film.
[0043] See Figure 5The process flow chart of depositing tungsten plugs is shown, the above-mentioned preset substrate includes a substrate 51 and a protective layer 52 located above the substrate, and the protective layer 52 can protect the substrate 51, such as including a TiN barrier layer, or including a TiN barrier layer and a nucleation layer. Fluorine-containing tungsten gas and hydrogen-containing gas are alternately introduced into the reaction chamber to perform atomic layer deposition reaction, and a fluorine-containing tungsten film 54 is deposited on the protective layer 52.
[0044] The fluorine-containing tungsten gas can undergo a reduction reaction with the hydrogen-containing gas to generate hydrogen fluoride and a fluorine-containing tungsten compound. The metal tungsten in the compound has good electrical conductivity and anti-electromigration properties. The fluorine-containing tungsten gas in this embodiment is preferably tungsten hexafluoride WF6.
[0045] Under certain process temperature and process pressure, fluorine-containing tungsten gas is first introduced into the reaction chamber for a certain time to allow a uniform layer of fluorine-containing metal molecules to be adsorbed on the surface of the wafer. Then, hydrogen-containing gas is introduced into the reaction chamber for a certain time to allow the hydrogen-containing gas to undergo a reduction reaction with the fluorine-containing tungsten molecules on the surface of the wafer to form a metal film. The generated hydrogen fluoride gas is pumped away, and the generated metal film contains lower fluorine impurities, which is called a fluorine-containing tungsten film.
[0046] By alternately introducing fluorine-containing tungsten gas and hydrogen-containing gas into the reaction chamber multiple times, a fluorine-containing tungsten film of a certain thickness can be generated. The number of times the fluorine-containing tungsten gas and hydrogen-containing gas are alternately introduced can be determined according to the required thickness of the fluorine-containing tungsten film. The greater the thickness, the more times required.
[0047] Step S404 , introducing fluorine-containing tungsten gas and hydrogen-containing gas into the reaction chamber simultaneously to perform a vapor deposition reaction to form a bulk tungsten layer.
[0048] After a fluorine-containing tungsten film of a certain thickness is grown, the growth of the bulk tungsten layer begins. Fluorine-containing tungsten gas and hydrogen-containing gas are simultaneously introduced into the reaction chamber to perform a chemical vapor deposition reaction to generate a bulk tungsten layer. The bulk tungsten layer is preferred in this embodiment.
[0049] The fluorine content of the fluorine-containing tungsten film is less than that of the bulk tungsten layer. The fluorine-containing tungsten film is the first line of defense to prevent fluorine from attacking the substrate and can prevent the penetration of byproduct fluorine atoms generated during the generation of the bulk tungsten layer.
[0050] The above-mentioned tungsten plug deposition process method provided in this embodiment can block a large number of byproduct fluorine atoms generated in the formation stage of the bulk tungsten layer from attacking the substrate by depositing a layer of fluorine-containing tungsten film before depositing the bulk tungsten layer. In addition, the fluorine impurity content in the fluorine-containing tungsten film is low, and the probability of attacking the substrate is small, which alleviates the problem of fluorine atoms penetrating the bottom substrate, avoids the occurrence of fluorine attack points inside the substrate that cause electrical failure of semiconductor devices, and improves the yield of semiconductor devices.
[0051] In one embodiment, in order to prevent fluorine atoms from attacking the substrate during the process of depositing the fluorine-containing tungsten film, before forming the fluorine-containing tungsten film, the process for depositing a tungsten plug provided by this embodiment further includes the following steps S400:
[0052] In step S400, hydrogen-containing gas is introduced into the reaction chamber to adsorb the hydrogen-containing gas on the surface of the protective layer to form a wetting layer; wherein the wetting layer reacts with fluorine, a byproduct generated during the formation of the fluorine-containing tungsten film, to generate a reduction reaction.
[0053] A certain flow rate of hydrogen-containing gas is continuously introduced into the reaction chamber, so that the above-mentioned preset substrate is immersed in the reaction chamber filled with hydrogen-containing gas. Figure 5 As shown, a layer of hydrogen-containing molecules is adsorbed on the surface of the protective layer above the substrate to form a wetting layer 53.
[0054] The hydrogen-containing gas may be any gas that can undergo a reduction reaction with the fluorine-containing tungsten gas to generate hydrogen fluoride, such as hydrogen, borane or silane. In this embodiment, hydrogen is preferred.
[0055] After the wetting layer is formed, the fluorine-containing tungsten film begins to grow. During the growth of the fluorine-containing tungsten film, fluorine atoms are produced as byproducts. When the fluorine atoms attack the underlying substrate, the hydrogen-containing molecules in the wetting layer react with the fluorine atoms to generate hydrogen fluoride gas, which is pumped away, thereby alleviating the fluorine attack. As the fluorine-containing tungsten film grows, the hydrogen-containing molecules in the wetting layer will gradually decrease. After the growth of the fluorine-containing tungsten film is completed, the wetting layer disappears.
[0056] The wetting layer is the second line of defense to prevent fluorine from attacking the substrate. The hydrogen-containing gas molecules in the wetting layer can react with the fluorine atoms produced during the formation of the fluorine-containing tungsten film to generate gaseous hydrogen fluoride which is then pumped away, thereby alleviating the fluorine attack during the formation of the fluorine-containing tungsten film.
[0057] By generating a wetting layer formed by hydrogen-containing gas on the protective layer of the substrate, the wetting hydrogen-containing gas can react with the by-product fluorine atoms generated during the formation of the fluorine-containing tungsten film to generate gaseous hydrogen fluoride which is pumped away, thereby alleviating fluorine attack during the formation of the fluorine-containing tungsten film.
[0058] In one embodiment, a specific implementation method for forming a wetting layer includes: stabilizing the pressure of the reaction chamber at a first preset pressure value, or increasing the pressure of the reaction chamber from a second preset pressure value to a third preset pressure value; continuously introducing a hydrogen-containing gas at a first preset flow value into the reaction chamber so that hydrogen atoms are adsorbed on the surface of the protective layer to form a wetting layer.
[0059] Based on the butterfly valve controller, the reaction chamber is controlled to maintain a certain pressure value (i.e., the first preset pressure value), or based on the butterfly valve controller, the pressure in the reaction chamber is controlled to gradually increase within a certain range (i.e., from the second preset pressure value to the third preset pressure value), and hydrogen-containing gas is introduced into the reaction chamber in a pulsed manner for a certain period of time. The hydrogen-containing gas will be adsorbed on the surface of the protective layer to form a wetting layer.
[0060] The second preset pressure value may be the same as or different from the first preset pressure value, the third preset pressure value may be the same as or different from the first preset pressure value, and the third preset pressure value is greater than the second preset pressure value.
[0061] In one embodiment, the process conditions for forming the wetting layer are:
[0062] The pressure of the reaction chamber is maintained at a first preset pressure value, the flow rate of the hydrogen-containing gas is maintained at a first preset flow rate value, and the duration of the introduction of the hydrogen-containing gas is 3s-100s, preferably 10-20s in this embodiment. The first preset pressure value ranges from 5Torr to 300Torr, preferably 40Torr in this embodiment; the first preset flow rate value ranges from 1000sccm to 10000sccm.
[0063] In another embodiment, the process conditions for forming the wetting layer are:
[0064] The pressure of the reaction chamber is in an increasing state, increasing from the second preset pressure value to the third preset pressure value, the flow rate of the hydrogen-containing gas is maintained at the first preset flow rate value, and the introduction time of the hydrogen-containing gas is 3s-100s, preferably 10-20s in this embodiment. The second preset pressure value ranges from 5Torr to 300Torr, and the third preset pressure value ranges from 5Torr to 300Torr.
[0065] In one embodiment, a specific implementation of forming a fluorine-containing tungsten film includes the following steps:
[0066] S500, heating the substrate to maintain the temperature of the substrate within a first preset temperature range, and stabilizing the pressure of the reaction chamber within a fourth preset pressure range.
[0067] The substrate is heated to stabilize the process temperature of the reaction chamber within a first preset temperature range of 250° C.-400° C. The process pressure in the reaction chamber is controlled to be stable within a fourth preset pressure range of 3 Torr-100 Torr, preferably 3 Torr-90 Torr.
[0068] S502, introducing fluorine-containing tungsten gas into the reaction chamber, and the flow rate of the fluorine-containing tungsten gas is set to a second preset flow rate value, and the introduction time of the fluorine-containing tungsten gas is set to a first preset time length, so that the fluorine-containing metal molecules are adsorbed on the surface of the wetting layer.
[0069] Fluorine-containing tungsten gas is introduced into the reaction chamber in a pulsed manner to adsorb a uniform layer of fluorine-containing metal molecules on the surface of the wafer. The second preset flow rate value of the fluorine-containing tungsten gas is in the range of 10sccm-500sccm, and the first preset time of the introduction of the fluorine-containing tungsten gas is in the range of 0.1s-5s.
[0070] S504, performing a purge process, and the duration of the purge process is set to a second preset duration to remove the fluorine-containing tungsten gas floating in the reaction chamber.
[0071] Purging is performed in the reaction chamber to remove excess fluorine-containing tungsten gas in the reaction chamber, leaving only fluorine-containing metal molecules adsorbed on the surface of the wafer. The duration of the purging process is set to a second preset duration, which ranges from 0.1s to 5s.
[0072] S506, introducing hydrogen-containing gas into the reaction chamber, and the flow rate of the hydrogen-containing gas is set to a third preset flow rate value, and the introduction time of the hydrogen-containing gas is set to a third preset time length, so that the hydrogen-containing gas and the fluorine-containing metal molecules undergo a reduction reaction to generate a fluorine-containing tungsten film.
[0073] Hydrogen-containing gas is introduced into the reaction chamber in a pulsed manner, and the hydrogen-containing gas undergoes a reduction reaction with the fluorine-containing metal molecules adsorbed on the wafer to generate a fluorine-containing tungsten film of a certain thickness (such as 0.02nm to 0.04nm, preferably 0.03nm) and hydrogen fluoride gas.
[0074] In one implementation, the third preset flow value ranges from 100 sccm to 10000 sccm, and the third preset time length ranges from 0.1 s to 5 s.
[0075] In the above-mentioned process of forming the fluorine-containing tungsten film, the fluorine-containing tungsten gas and the hydrogen-containing gas are alternately introduced, and the content of fluorine impurities in the fluorine-containing tungsten film is lower than the content of fluorine atoms in the bulk tungsten layer. The content of fluorine impurities in the fluorine-containing tungsten film can be e per cubic centimeter. +19 Fluorine atoms. The fluorine impurity content in the bulk tungsten layer can be e per cubic centimeter. +20 Fluorine atom.
[0076] S508, performing a purge process, and the duration of the purge process is set to a fourth preset duration to remove the hydrogen-containing gas in the reaction chamber and the hydrogen fluoride gas generated by the reduction reaction.
[0077] Purging is performed in the reaction chamber to remove excess hydrogen-containing gas in the reaction chamber and hydrogen fluoride gas generated by the reaction of the hydrogen-containing gas with the fluorine-containing metal molecules. The fourth preset time length ranges from 0.1s to 5s, and the first preset time length, the second preset time length, the third preset time length, and the fourth preset time length may be the same or different.
[0078] In one embodiment, the above steps S500 to S508 are executed cyclically for a preset number of times to form a fluorine-containing tungsten film of a preset thickness. The preset number of times is related to the required preset thickness of the fluorine-containing tungsten film.
[0079] In one embodiment, the predetermined thickness of the fluorine-containing tungsten film may be greater than 1 nm.
[0080] The above-mentioned tungsten plug deposition process method provided in this embodiment plays a role in blocking fluorine atoms from penetrating the substrate by growing a fluorine-containing tungsten film between the nucleation layer and the bulk tungsten layer, thereby solving the problem of fluorine atoms attacking the bottom substrate; by adsorbing a wetting layer on the surface of the nucleation layer, the wetting hydrogen-containing gas can react with the fluorine atoms generated in the process of generating the fluorine-containing tungsten film, generating gaseous hydrogen fluoride which is pumped away, thereby alleviating the fluorine attack.
[0081] Based on the above-mentioned embodiment, this embodiment provides a process for depositing a tungsten plug. Figure 6 Another process flow chart for depositing tungsten plugs is shown, and specific steps can be referred to as follows:
[0082] Step S601 , providing a substrate 51 , and forming a Ti / TiN barrier layer 61 on the substrate.
[0083] Step S602 , heating the substrate 51 to a preset process temperature.
[0084] A nucleation layer 62 is generated on the surface of the Ti / TiN barrier layer 61. Figure 7 In the process of forming the nucleation layer 62 after heating the substrate 51, the following steps S71 to S74 are cyclically executed to form the nucleation layer of a set thickness:
[0085] S71: continuously introducing a B2H6 pulse into the reaction chamber for a predetermined time;
[0086] S72: introducing an inert gas into the reaction chamber to purge the reaction chamber to remove excess B2H6 gas in the reaction chamber;
[0087] S73: continuously introducing WF6 pulses for a predetermined time into the reaction chamber;
[0088] S74: Introduce an inert gas into the reaction chamber to purge the reaction chamber to remove excess WF6 gas in the reaction chamber.
[0089] The number of times steps S71 to S74 are cyclically executed can be determined according to the required thickness of the nucleation layer. The more times steps S71 to S74 are executed, the thicker the nucleation layer formed will be.
[0090] Step S603 , introducing a H 2 pulse with a duration of 3 s to 100 s into the reaction chamber, so that the H 2 molecules are adsorbed on the surface of the nucleation layer 62 to form a wetting layer 53 .
[0091] The flow rate of the H2 pulse can range from 1000 sccm to 10000 sccm; the reaction chamber is controlled to maintain a certain pressure, or the pressure of the reaction chamber is controlled to increase. The pressure range of the reaction chamber needs to be maintained at 5 Torr-300 Torr, preferably 40 Torr.
[0092] In step S604 , WF6 pulses and H2 pulses are alternately introduced into the reaction chamber to form a fluorine-containing tungsten film 54 .
[0093] The WF6 molecules adsorbed on the wafer surface react with H2 by atomic layer deposition to generate a tungsten film containing less fluorine impurities, which is called a fluorine-containing tungsten film.
[0094] During the growth process of the fluorine-containing tungsten film, fluorine atoms are produced as byproducts. The hydrogen molecules in the wetting layer 53 react with the fluorine atoms to generate hydrogen fluoride gas which is extracted, thereby alleviating the fluorine attack. As the fluorine-containing tungsten film grows, the hydrogen molecules in the wetting layer will gradually decrease. After the growth of the fluorine-containing tungsten film 54 is completed, the wetting layer 53 disappears.
[0095] The process conditions for generating the fluorine-containing tungsten film are as follows: the process temperature is between 250-400° C., the process pressure is between 3 Torr-100 Torr, preferably between 3 Torr-90 Torr; the flow rate of the WF6 pulse is between 10 sccm-500 sccm, and the flow rate of the H2 pulse is between 100 sccm-10000 sccm.
[0096] like Figure 7 As shown, the following steps S75 to S78 are executed cyclically to generate a nucleation layer of a certain thickness:
[0097] S75, introducing a WF6 pulse with a duration of 0.1s-5s into the reaction chamber, and the flow rate of the WF6 pulse is in the range of 10sccm-500sccm;
[0098] S76, introducing an inert gas into the reaction chamber to perform a purge process to remove excess WF6 gas in the reaction chamber except for a layer of WF6 molecules adsorbed on the surface of the wafer, and the time range of the purge process is 0.1s-5s;
[0099] S77, introducing a H2 pulse with a duration of 0.1s-5s into the reaction chamber, so that the H2 molecules react with a layer of WF6 molecules adsorbed on the surface of the wafer to generate a fluorine-containing tungsten film 54, and the flow rate of the H2 pulse is in the range of 100sccm-10000sccm;
[0100] S78, introducing an inert gas into the reaction chamber to perform a purge process to remove excess H2 and hydrogen fluoride gas generated by the reduction reaction in the reaction chamber. The purge process time ranges from 0.1s to 5s.
[0101] The number of times steps S75 to S78 are cyclically executed can be determined according to the required thickness of the fluorine-containing tungsten film.
[0102] In step S605 , WF6 pulses and H2 pulses are simultaneously introduced into the reaction chamber to perform a vapor deposition reaction to form a bulk tungsten layer 55 .
[0103] The tungsten plug deposition process provided in this embodiment solves the problem of fluorine attacking the substrate. The fluorine-containing tungsten film itself has the characteristics of low fluorine content and low probability of fluorine attacking the substrate. The formation of the fluorine-containing tungsten film can also block the large amount of fluorine atoms generated during the formation of the tungsten layer from attacking the substrate, thereby avoiding fluorine atoms attacking the substrate and causing electrical failure of the semiconductor device, thereby improving the yield of the semiconductor device.
[0104] Corresponding to the tungsten plug deposition process provided in the above embodiment, the present invention provides a semiconductor device, including: a contact hole, see Figure 8 As shown in the hole filling schematic diagram, a fluorine-containing tungsten film 54 and a bulk tungsten layer 55 are deposited on the protective layer of the contact hole substrate 51. The fluorine-containing tungsten film 54 and the bulk tungsten layer 55 are deposited based on the process method for depositing tungsten plugs provided in the above-mentioned embodiment, and the fluorine-containing tungsten film 54 is located between the protective layer and the bulk tungsten layer 55.
[0105] In one embodiment, the protective layer includes a barrier layer 61 and a nucleation layer 62 , and the barrier layer 61 is located between the substrate 51 and the nucleation layer 62 .
[0106] The contact hole process provided in this embodiment can adopt the tungsten plug deposition process method provided in the above embodiment. In one implementation, a wetting layer can also be included between the nucleation layer 62 and the fluorine-containing tungsten film 54. The wetting layer is a layer of hydrogen molecules uniformly adsorbed on the surface of the nucleation layer. The by-product fluorine atoms generated during the formation of the fluorine-containing tungsten film 54 react with the hydrogen molecules in the wetting layer to generate hydrogen fluoride gas, which is drawn away. The wetting layer gradually disappears during the formation of the fluorine-containing tungsten film 54.
[0107] The semiconductor device provided in this embodiment has the same implementation principle and technical effects as those of the aforementioned embodiments. For the sake of brief description, reference may be made to the corresponding contents in the aforementioned method embodiments for matters not mentioned in the semiconductor device embodiment.
[0108] An embodiment of the present invention provides a computer-readable medium, wherein the computer-readable medium stores computer-executable instructions. When the computer-executable instructions are called and executed by a processor, the computer-executable instructions prompt the processor to implement the method described in the above embodiment.
[0109] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system described above can refer to the corresponding process in the aforementioned embodiment, and will not be repeated here.
[0110] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., which can store program codes.
[0111] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.
[0112] Finally, it should be noted that the above-described embodiments are only specific implementations of the present invention, which are used to illustrate the technical solutions of the present invention, rather than to limit them. The protection scope of the present invention is not limited thereto. Although the present invention is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed by the present invention, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.
Claims
1. A process for depositing a tungsten plug, for processing a preset substrate, wherein the preset substrate comprises a substrate and a protective layer located above the substrate, characterized in that: The process for depositing the tungsten plug comprises: Alternately introducing fluorine-containing tungsten gas and hydrogen-containing gas into the reaction chamber to perform atomic layer deposition reaction to form a fluorine-containing tungsten film; The fluorine-containing tungsten gas and the hydrogen-containing gas are simultaneously introduced into the reaction chamber to perform a vapor deposition reaction to form a bulk tungsten layer; wherein the fluorine content of the fluorine-containing tungsten film is less than the fluorine content of the bulk tungsten layer.
2. The process for depositing a tungsten plug according to claim 1, characterized in that: Before forming the fluorine-containing tungsten film, the process for depositing a tungsten plug further includes: A hydrogen-containing gas is introduced into the reaction chamber to adsorb the hydrogen-containing gas on the surface of the protective layer to form a wetting layer; wherein the wetting layer produces a reduction reaction with fluorine, a byproduct produced during the formation of the fluorine-containing tungsten film.
3. The process for depositing a tungsten plug according to claim 2, characterized in that: The step of introducing hydrogen-containing gas into the reaction chamber so that the hydrogen-containing gas is adsorbed on the surface of the protective layer to form a wetting layer comprises: Stabilize the pressure of the reaction chamber at a first preset pressure value, or increase the pressure of the reaction chamber from a second preset pressure value to a third preset pressure value; A hydrogen-containing gas at a first preset flow rate is continuously introduced into the reaction chamber so that hydrogen atoms are adsorbed on the surface of the protective layer to form the wetting layer.
4. The process for depositing a tungsten plug according to claim 3, characterized in that: The first preset flow rate value ranges from 1000 sccm to 10000 sccm; and / or, The first preset pressure value, the second preset pressure value and the third preset pressure value are all in the range of 5 Torr-300 Torr.
5. The process for depositing a tungsten plug according to claim 2, characterized in that: The step of alternately introducing a fluorine-containing tungsten gas and a hydrogen-containing gas into the reaction chamber to perform an atomic layer deposition reaction to form a fluorine-containing tungsten film comprises: S500, heating the substrate to maintain the temperature of the substrate within a first preset temperature range, and stabilizing the pressure of the reaction chamber within a fourth preset pressure range; S502, introducing the fluorine-containing tungsten gas into the reaction chamber, and the flow rate of the fluorine-containing tungsten gas is set to a second preset flow rate value, and the introduction time of the fluorine-containing tungsten gas is set to a first preset time length, so that the fluorine-containing metal molecules are adsorbed on the surface of the wetting layer; S504, performing a purge process, wherein the duration of the purge process is set to a second preset duration, so as to remove the fluorine-containing tungsten gas floating in the reaction chamber; S506, introducing the hydrogen-containing gas into the reaction chamber, and the flow rate of the hydrogen-containing gas is set to a third preset flow rate value, and the introduction time of the hydrogen-containing gas is set to a third preset duration, so that the hydrogen-containing gas and the fluorine-containing metal molecules undergo a reduction reaction to generate a fluorine-containing tungsten film; S508 , performing a purge process, wherein the duration of the purge process is set to a fourth preset duration, so as to remove the hydrogen-containing gas in the reaction chamber and the hydrogen fluoride gas generated by the reduction reaction.
6. The process for depositing a tungsten plug according to claim 5, characterized in that: Also includes: The steps S500 to S508 are executed cyclically for a preset number of times to form the fluorine-containing tungsten film with a preset thickness.
7. The process for depositing a tungsten plug according to claim 5, characterized in that: The first preset temperature range is 250°C-400°C; and / or, The fourth preset pressure range is 3 Torr-100 Torr; and / or, The second preset flow rate value ranges from 10 sccm to 500 sccm; and / or, The third preset flow rate value ranges from 100 sccm to 10000 sccm.
8. The process for depositing a tungsten plug according to claim 5, characterized in that: The range of the first preset time length, the second preset time length, the third preset time length and the fourth preset time length are all 0.1s-5s; and / or, The range of the preset thickness is greater than 1 nm.
9. A semiconductor device comprising: A contact hole, characterized in that a fluorine-containing tungsten film and a bulk tungsten layer are deposited on the protective layer of the contact hole substrate, the fluorine-containing tungsten film and the bulk tungsten layer are deposited based on the process method for depositing tungsten plugs according to any one of claims 1 to 8, and the fluorine-containing tungsten film is located between the protective layer and the bulk tungsten layer.
10. The semiconductor device according to claim 9, characterized in that The protective layer includes a barrier layer and a nucleation layer, and the barrier layer is located between the substrate and the nucleation layer.