Method and apparatus for depositing thin film

Abstract

The invention discloses a method and equipment for depositing a thin film, and belongs to the technical field of semiconductors. The method comprises the steps that the set thickness of a film is obtained; determining deposition time of the film according to the thickness; preheating the substrate material in the cavity of the PVD equipment to a preset stable temperature; nitrogen and argon are controlled to enter the cavity, and the flow of the nitrogen and the flow of the argon are controlled to be stabilized at the first stable flow and the second stable flow; the power of the PVD equipment is controlled to be preset ignition power, and the real-time flow of the nitrogen and the real-time flow of the argon are adjusted to be the first ignition flow and the second ignition flow correspondingly; and the power is increased to preset deposition power at the preset power climbing rate, and the PVD reactive sputtering film forming time is controlled according to the deposition time. Wherein the preset stable temperature is 300 DEG C, the preset ignition power is 500 watts, the preset deposition power is 6000 watts, and the preset power climbing rate is 4000 watts per second. The resistance of the deposited film can be reduced.

Description

Technical Field

[0001] The present application relates to the field of semiconductor technology, and in particular to a method and device for depositing a thin film. Background Art

[0002] In the process of semiconductor chip manufacturing, the industry often uses magnetron sputtering technology in physical vapor deposition (PVD) to deposit titanium nitride (TiN) film. However, the TiN film deposited by this process has a high resistance. In order to reduce the sheet resistance of the TiN layer, it is usually necessary to increase the thickness of the TiN film, which leads to increased material costs and limits the structure line width. Especially when the process node is less than 0.25 microns (μm), the thickness of the TiN film used in structures such as contact holes / metal (Contact / Metal) or top vias (Top Via) is required to be thinner and thinner (from tens of nanometers to a few nanometers), which further increases its sheet resistance. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a method and an apparatus for depositing a thin film, so as to solve the problem of high resistance of the thin film deposited in the existing process.

[0004] In order to achieve the above-mentioned object, the first aspect of the present application provides a method for depositing a thin film, the method comprising:

[0005] Get the set thickness of the film;

[0006] Determine the deposition time of the film according to the thickness;

[0007] Preheating the substrate material in the chamber of the PVD equipment to a preset stable temperature;

[0008] Controlling nitrogen and argon to enter the chamber and controlling the flow rates of the nitrogen and argon to be stable at a first stable flow rate and a second stable flow rate;

[0009] Controlling the power of the PVD device to a preset ignition power, and adjusting the real-time flow rates of nitrogen and argon to a first ignition flow rate and a second ignition flow rate, respectively;

[0010] The power is increased to a preset deposition power at a preset power ramp rate, and the time of reactive sputtering film formation of the PVD equipment is controlled according to the deposition time;

[0011] Among them, the preset stable temperature is 300°C, the preset ignition power is 500 watts, the preset deposition power is 6000 watts, and the preset power climbing rate is 4000 watts per second.

[0012] In the embodiment of the present application, the first stable flow rate is greater than the second stable flow rate, the first ignition flow rate is greater than the second ignition flow rate, and the preset deposition power is greater than the preset ignition power.

[0013] In the embodiment of the present application, the first stable flow rate is 85 sccm, and the second stable flow rate is 25 sccm.

[0014] In the embodiment of the present application, the first ignition flow rate is 40 sccm, and the second ignition flow rate is 20 sccm.

[0015] A second aspect of the present application provides a PVD device, which includes a chamber; a flow valve; and a controller, and is configured to perform the above-mentioned method for depositing a thin film.

[0016] Through the above technical solution, the set thickness of the film is first obtained, and the deposition time of the film is determined according to the thickness. Then the substrate material in the chamber of the PVD equipment is preheated to a preset stable temperature, and the nitrogen and argon gases are controlled to enter the chamber and the flow rates of the nitrogen and argon gases are controlled to be stable at the first stable flow rate and the second stable flow rate. After the materials and gases in the chamber are in a stable state, the power of the PVD equipment is controlled to the preset ignition power, and the real-time flow rates of the nitrogen and argon gases are adjusted to the first ignition flow rate and the second ignition flow rate, respectively. Finally, the power of the chamber is increased to the preset deposition power at a preset power ramp rate, the deposition of the film is started, and the time of the reactive sputtering film formation of the PVD equipment is controlled according to the deposition time, thereby reducing the resistance of the film.

[0017] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. In the accompanying drawings:

[0019] Figure 1 A flow chart of a method for depositing a thin film according to an embodiment of the present application is schematically shown;

[0020] Figure 2 A schematic diagram showing a change trend of the resistivity of a TiN film according to an embodiment of the present application;

[0021] Figure 3 A cross-sectional view of a TiN film according to an embodiment of the present application is schematically shown. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the specific implementation methods described herein are only used to illustrate and explain the embodiments of the present application, and are not used to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0023] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0024] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0025] Figure 1 A flow chart of a method for depositing a thin film according to an embodiment of the present application is schematically shown. Figure 1 As shown, an embodiment of the present application provides a method for depositing a thin film, which may include the following steps.

[0026] Step 101: Obtaining a set thickness of the film;

[0027] In the embodiment of the present application, the set thickness of the film can be determined according to the application scenario of the film. The set thickness can be the optimal thickness determined by the program according to the relevant algorithm, or it can be a preferred thickness determined based on experience.

[0028] Step 102: Determine the deposition time of the thin film according to the thickness;

[0029] In an embodiment of the present application, after obtaining the set thickness of the film, the corresponding specific film deposition rate and set thickness can be determined according to the PVD equipment and process conditions used, so that the deposition time required for depositing the film can be determined.

[0030] Step 103: preheating the substrate material in the chamber of the PVD equipment to a preset stable temperature;

[0031] Step 104: Control nitrogen and argon to enter the chamber and control the flow rates of the nitrogen and argon to be stable at a first stable flow rate and a second stable flow rate;

[0032] In the embodiment of the present application, the film may be a TiN film. In the process of forming the TiN film, nitrogen is a reaction gas, and TiN is generated by the reaction of titanium (Ti) and nitrogen. Therefore, the flow rate of nitrogen directly affects the nitrogen content in the film layer, and further affects the composition and performance of the TiN film. The stability of the nitrogen flow rate ensures that the TiN film formed during the film formation process is uniform and meets the desired chemical composition.

[0033] In one embodiment, the PVD device may be an Endura 5500 platform PVD device. Preferably, the preset stable temperature may be 300° C., the first stable flow rate may be 85 sccm (standard cubic centimeter per minute), and the second stable flow rate may be 25 sccm.

[0034] Step 105: Control the power of the PVD device to a preset ignition power, and adjust the real-time flow rates of nitrogen and argon to a first ignition flow rate and a second ignition flow rate, respectively;

[0035] In the embodiment of the present application, after the substrate material, nitrogen and argon are in a stable state, that is, after the above conditions are met, the power of the PVD device is controlled to a preset ignition power, and when the PVD device is ignited, the real-time flow rates of nitrogen and argon are adjusted again to the first ignition flow rate and the second ignition flow rate, so that the chamber of the PVD device reaches the best ignition environment. Preferably, the preset ignition power can be 500 watts, the first ignition flow rate can be 40 sccm, and the second ignition flow rate can be 20 sccm.

[0036] In one embodiment, the PVD equipment applies voltage to the target (titanium) to generate an electric field between the target surface and the gas. The preset ignition power of 500 watts means that the PVD equipment provides 500 watts of energy to the sputtering process, which will determine the sputtering rate. Higher power generally means more energy is used to accelerate the ions in the plasma, causing them to hit the target surface and release more titanium atoms, thereby increasing the deposition rate. Adjusting the flow rate of nitrogen to the first ignition flow rate is to control the amount of reactive gas to ensure that titanium reacts with nitrogen to form a TiN film. Argon is an inert gas mainly used to excite plasma. Argon ions (Ar + )By bombarding the target with plasma, titanium atoms are sputtered out from the target surface to form deposited material. +) are positively charged argon atoms generated in the plasma. They are accelerated by the electric field and hit the titanium target, releasing the titanium atoms from the target surface as material deposited on the substrate. Under the above conditions, ignition can be achieved in as little as 3 seconds. Ignition refers to the process in which argon gas is ionized to form plasma after an electric field is applied during the physical vapor deposition (PVD) process. The successful generation of plasma within 3 seconds after the PVD equipment is started indicates that under the above scheme, the physical vapor deposition reaction is rapid and the plasma is stably formed.

[0037] Step 106: increasing the power to a preset deposition power at a preset power ramp rate, and controlling the PVD reactive sputtering film forming time according to the deposition time;

[0038] Step 107: wherein the preset stabilization temperature is 300° C., the preset ignition power is 500 watts, the preset deposition power is 6000 watts, and the preset power ramp rate is 4000 watts per second.

[0039] In an embodiment of the present application, this step is to deposit a TiN film. The above steps are mainly to prepare for the film forming process, such as preheating the substrate material and stabilizing the gas flow rate. Ramp-rate represents the rate of increase of power. Preferably, the preset power ramp rate can be 4KW / S, which means that the speed at which the power rises from a low value to 6KW is 4KW per second. Therefore, the PVD equipment will increase from 0W to 6KW in about 1.5 seconds. This gradual increase in power helps prevent sudden energy changes from having an adverse effect on the target material and the substrate. The PVD equipment increases from 500W to 6KW at a rate of 4KW / S, which can increase the energy of the plasma during the sputtering process and accelerate the sputtering rate. Sputtering film formation refers to the Ti target being bombarded by Ar ions to release titanium atoms, which then react with nitrogen in nitrogen to form a TiN film.

[0040] In one embodiment, the sputtering film formation can be roughly divided into three steps. That is, Ar ions bombard the Ti target: at a power of 6KW, argon (Ar) is ionized into argon ions (Ar + ), these argon ions are accelerated by the electric field and bombard the surface of the titanium target, sputtering titanium atoms from the target surface; Ti ions react with N ions to form TiN: the sputtered titanium atoms (or ions) react with nitrogen ions (N + ) undergoes a chemical reaction to generate TiN (titanium nitride). This reaction occurs in a plasma environment; the TiN film is deposited on the substrate: TiN molecules are gradually deposited on the surface of the substrate to form a dense TiN film.

[0041] In the embodiment of the present application, the film deposition rate depends on factors such as the power of the PVD equipment, the gas flow rate and the sputtering efficiency. Preferably, the film deposition rate can be That is, the film thickness increases by The film deposition rate can also be determined according to the actual application scenario. In steps 101 and 102, after obtaining the set thickness of the film, the deposition time of the film can be determined according to the set thickness and the above-mentioned film deposition rate. For example, if the required TiN film thickness is Then according to the deposition rate The deposition time should be 100 seconds.

[0042] Through the above technical solution, the set thickness of the film is first obtained, and the deposition time of the film is determined according to the thickness. Then the substrate material in the chamber of the PVD equipment is preheated to a preset stable temperature, and the nitrogen and argon gases are controlled to enter the chamber and the flow rates of the nitrogen and argon gases are controlled to be stable at the first stable flow rate and the second stable flow rate. The plasma is efficiently generated to ensure that the deposition of the TiN film has high stability and uniformity. After the materials and gases in the chamber are in a stable state, the power of the PVD equipment is controlled to the preset ignition power, and the real-time flow rates of nitrogen and argon gases are adjusted to the first ignition flow rate and the second ignition flow rate, respectively. Finally, the power of the chamber is increased to the preset deposition power at a preset power ramp rate, and the deposition of the film begins. The time of the reactive sputtering film formation of the PVD equipment is controlled according to the deposition time to improve the sputtering efficiency and reduce film defects, so as to reduce the resistance of the film and improve the uniformity of the film.

[0043] In the embodiment of the present application, the first stable flow rate is greater than the second stable flow rate, the first ignition flow rate is greater than the second ignition flow rate, and the preset deposition power is greater than the preset ignition power.

[0044] In the embodiment of the present application, the preset stabilization temperature may be 300°C.

[0045] In the embodiment of the present application, the first stable flow rate may be 85 sccm, and the second stable flow rate may be 25 sccm.

[0046] In an embodiment of the present application, the preset ignition power may be 500 watts, and the preset deposition power may be 6000 watts.

[0047] In the embodiment of the present application, the first ignition flow rate may be 40 sccm, and the second ignition flow rate may be 20 sccm.

[0048] The following is a process formula table of physical vapor deposition of low-resistance TiN according to an embodiment of the present application. As shown in Table 1. The first step (Stabilization) and the second step (Preheat) are the stabilization stage of the substrate material (Wafer) to be film-formed entering the process chamber. This stage includes preheating the substrate to be coated (preheating to the process temperature of 300°C), stabilizing the N 2The flow rate of Ar is the same as that of N in the chamber. 2 The flow rate of Ar is relatively large, and the time for the first step of stabilization and the second step of preheating the substrate material is controlled to be 5S and 10S respectively. At this stage, TiN has not started to form a film, and the DC power supply (that is, the power of the PVD equipment), Ramp-rate (the rate of increase of DC power) and gas pressure control Wafer Gas Pressure (mTorr) are all set to zero. Peressure pressure, no pressure control is performed during the deposition process. The Gate vacuum valve is set to Full (the valve is fully open to maintain vacuum). The Proc Press process pressure is 0. Position is the distance between the substrate material and the target material. The third step Strike is the ignition and glowing stage, and the DC power is set to 500W, N 2 The flow rates of Ar and Ar are adjusted to 40sccm and 20sccm, and the ignition is carried out within 3S to generate a small amount of Ar+ ions. The fourth step is the main film formation step of the process. In this stage, the DC Power is increased to 6KW, and the Ramp-rate is set to 4KW / S. This stage is PVD reactive sputtering film formation. In this stage, Ar ions bombard the Ti target to generate Ti ions, which react with the ionized N ions to generate TiN deposited on the substrate to form a TiN film. Under this process condition, the deposition rate of the TiN film is The TiN film deposition time can be calculated and set according to the thickness requirements. Step 5 After the TiN film deposition is completed, turn off the DC Power and turn off the N 2 With the Ar flow rate (set to zero), the vacuum pump on the equipment end evacuates the vacuum and transfers the coated substrate out through the equipment platform robotic arm.

[0049] Table 1

[0050]

[0051] Figure 2 The change trend diagram of the resistivity of the TiN film according to the embodiment of the present application is schematically shown. Figure 2 shown. Figure 2 The resistivity (ρ, solid curve) and uniformity (Uni%, dashed curve) of TiN films are shown as the N 2 / Ar gas ratio variation trend diagram. Figure 2 For the STD TiN process chamber of the Endura5500 platform PVD equipment, the Sputter DCPower is constantly controlled to be 6KW, Spacing5900steps (the distance between the Wafer and the Target during the process), and the process temperature is adjusted at 300℃ for different N 2The change curve of the resistivity and thickness uniformity of TiN (the thickness of TiN film is controlled at 120nm+ / -5nm) obtained by adjusting the gas flow ratio of nitrogen (N 2 ) and argon (Ar) flow ratio, ranging from 0.50 to 4.67. 2 The Ar / Ar ratio represents the ratio of the reaction gases in the film formation process, which affects the composition, structure and properties of the TiN film. The left vertical axis represents the resistivity ρ of the TiN film, and the solid curve represents the changing trend of the resistivity. The resistivity reflects the conductive properties of the film, and generally lower resistivity means better conductivity. The right vertical axis represents the uniformity of the TiN film, expressed as a percentage, and the dotted curve shows the changing trend of the film uniformity. A lower uniformity value (U%) indicates that the film is more evenly distributed on the substrate surface, and generally the better the uniformity, the higher the quality of the film. As N 2 With the increase of N / Ar ratio, the resistivity shows a trend of large fluctuation. 2 / Ar ratio, the resistivity is high, about 450μΩ·cm. As the gas ratio increases, the resistivity decreases, but 2 When the N / Ar ratio is about 1.0, a peak value (137.10 μΩ·cm) appears. After that, the resistivity tends to be stable. 2 The lowest point (1.94μΩ·cm) is reached when the / Ar ratio is around 1.94. 2 / Ar ratio fluctuates violently and has poor uniformity, especially between 0.5 and 1.0. 2 As the / Ar ratio increases, the uniformity gradually improves. 2 When the Ar / Ar ratio is close to 1.94, the uniformity reaches the best (1.94%) and then remains basically stable. 2 When the Ar / Ar ratio is 1.94, the resistivity is 1.94μΩ·cm and the uniformity is close to 1.94%, which is an ideal point, indicating that the TiN film has the best resistivity and uniformity under this gas ratio.

[0052] Figure 3 A cross-sectional view of a TiN film according to an embodiment of the present application is schematically shown. Figure 3 As shown, in the embodiment of the present application, the sum of the film segment thickness represented by 121.3nm and the film segment thickness represented by 216.1nm is not much different from the entire TiN film thickness of 335.1nm. It can be seen that the TiN film deposited by the above technical solution can ensure that the thickness difference of the TiN film at different positions is within an acceptable range, thereby ensuring that the uniformity of the TiN film is improved while reducing the resistance of the TiN film.

[0053] The present application also provides a PVD device, which may include:

[0054] A chamber for providing a reaction vessel for depositing a thin film;

[0055] Flow valves, used to control the flow of nitrogen and argon;

[0056] A controller is configured to execute the above method for depositing a thin film.

[0057] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0058] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0059] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0060] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0061] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0062] The memory may include non-permanent memory in a computer-readable medium, random access memory (RAM) and / or non-volatile memory in the form of read-only memory (ROM) or flash RAM. The memory is an example of a computer-readable medium.

[0063] Computer readable media include permanent and non-permanent, removable and non-removable media that can be implemented by any method or technology to store information. Information can be computer readable instructions, data structures, program modules or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer readable media does not include temporary computer readable media (transitory media), such as modulated data signals and carrier waves.

[0064] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0065] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for depositing a thin film, characterized in that: The method comprises: Obtaining a set thickness of the film; determining a deposition time of the thin film according to the thickness; Preheating the substrate material in the chamber of the PVD equipment to a preset stable temperature; Controlling nitrogen and argon to enter the chamber and controlling the flow rates of the nitrogen and argon to be stable at a first stable flow rate and a second stable flow rate; Controlling the power of the PVD device to a preset ignition power, and adjusting the real-time flow rates of the nitrogen gas and the argon gas to a first ignition flow rate and a second ignition flow rate, respectively; Raising the power to a preset deposition power at a preset power ramp rate, and controlling the time of reactive sputtering film formation of the PVD device according to the deposition time; Among them, the preset stable temperature is 300° C., the preset ignition power is 500 watts, the preset deposition power is 6000 watts, and the preset power climbing rate is 4000 watts per second.

2. The method according to claim 1, characterized in that The first stable flow rate is greater than the second stable flow rate, the first ignition flow rate is greater than the second ignition flow rate, and the preset deposition power is greater than the preset ignition power.

3. The method according to claim 1, characterized in that The first stable flow rate is 85 sccm, and the second stable flow rate is 25 sccm.

4. The method according to claim 1, characterized in that: The first ignition flow rate is 40 sccm, and the second ignition flow rate is 20 sccm.

5. A PVD device, characterized in that: include: Chamber; Flow valve; A controller configured to execute the method for depositing a thin film according to any one of claims 1 to 4.

Images