WO2023045835A1

WO2023045835A1 - Preparation method for metal compound film

Info

Publication number: WO2023045835A1
Application number: PCT/CN2022/119220
Authority: WO
Inventors: 马迎功; 郭冰亮; 武树波; 赵晨光; 周麟; 宋玲彦; 杨健; 甄梓杨; 翟洪涛; 段俊雄; 师帅涛; 许文学; 张璐; 崔亚欣
Original assignee: 北京北方华创微电子装备有限公司
Priority date: 2021-09-24
Filing date: 2022-09-16
Publication date: 2023-03-30
Also published as: TWI810071B; CN113862622A; CN113862622B; TW202314008A

Abstract

Disclosed is a preparation method for a metal compound film, comprising: step 1: placing into a reaction chamber a tray carrying a wafer onto which a film is to be deposited, the tray being located above a base; and step 2: introducing a first mixed gas of a first inert gas and a process gas into the reaction chamber, and applying excitation power to a metal target in the reaction chamber, so that the first mixed gas forms a plasma, and the plasma bombards the metal target to form a metal compound film on the wafer; and at the same time, applying radio frequency bias power to the base to adjust the stress of the metal compound film. In step 2 of the present invention, the radio frequency bias power is applied to the base to adjust the stress of the metal compound film when the metal compound film is formed on the wafer. The problem that a film is bent and even falls off under stress is solved, thereby improving the reliability of a device.

Description

Preparation method of metal compound film

technical field

The invention relates to the field of semiconductor technology, and more specifically, to a method for preparing a metal compound thin film.

Background technique

Physical vapor deposition (Physical Vapor Deposition, referred to as PVD), as a thin film deposition technology, is mainly used in the deposition of various functional thin films, and is widely used in semiconductor fields such as integrated circuits, solar cells, and LEDs.

Aluminum nitride (AlN) thin films have been widely used as buffer layers or piezoelectric layers in LEDs, micro-electro-mechanical systems (Micro-Electro-Mechanical System, MEMS), high electron mobility transistors (High Electron Mobility Transistor, HEMT) and other fields . Ideally, the stress of the AlN film is zero. If the stress of the AlN film is too large, the film will be bent or even fall off due to force, which will affect the reliability of the device. As a piezoelectric layer, AlN films are mainly deposited on Si substrates or SiO ₂ substrates, which require stress in the range of 0±100Mpa in MEMS applications. When process parameters such as temperature, sputtering gas, and pressure are optimized, and other process parameters are kept constant, the stress of the AlN film is basically unchanged, and it is difficult to adjust the stress of AlN (with a thickness of 500nm to 1500nm).

Therefore, for the deposition of AlN thin films on Si substrates or SiO ₂ substrates, it is very important to find a new stress-tunable AlN thin film preparation method.

Contents of the invention

The purpose of the present invention is to propose a kind of preparation method of metal compound thin film, solve the problem that thin film is bent under force, even falls off, and then improves the reliability of device, described preparation method comprises:

Step 1: Put the tray carrying the wafer to be deposited into the reaction chamber and place it above the base;

Step 2: Introduce a first mixed gas of a first inert gas and a process gas into the reaction chamber, apply excitation power to the metal target in the reaction chamber, and make the first mixed gas form a plasma, The plasma bombards the metal target to form a metal compound film on the wafer; at the same time, RF bias power is applied to the susceptor to adjust the stress of the metal compound film.

In an optional solution, after the step 2, it also includes:

Step 3: Introduce a second inert gas into the reaction chamber, and apply radio frequency bias power to the susceptor, so that the second inert gas forms a plasma, and the plasma formed by the second inert gas is The surface of the metal compound film is etched to further adjust the stress of the metal compound film.

In an optional solution, after the step 1, and before the step 2, it also includes:

Step 101: heating the tray and the wafer to a preset temperature to remove moisture from the tray and the wafer and organic impurities attached to the surface of the wafer.

In an optional solution, after the step 101, and before the step 2, it also includes:

Step 102: Flowing a third inert gas into the reaction chamber, and applying radio frequency bias power to the susceptor, so that the third inert gas forms a plasma, and the plasma formed by the third inert gas bombarding the surface of the wafer to remove impurities on the surface of the wafer.

In an optional solution, after the step 102 and before the step 2, the method further includes:

Step 103: Move the baffle to cover the wafer, pass the second mixed gas of the fourth inert gas and the process gas into the reaction chamber, apply excitation power to the metal target, and make the The second mixed gas forms plasma and performs a pre-sputtering process; after the gas flow rate of the second mixed gas and the excitation power introduced into the reaction chamber are stabilized, the baffle is removed from the crystal The upper part of the circle is removed, and the excitation power and the gas flow rate of the second mixed gas are kept constant.

In an optional solution, the flow rate of the first inert gas is less than or equal to 200 sccm, and the flow rate of the process gas is less than or equal to 500 sccm; the flow ratio of the process gas to the first inert gas is greater than or equal to 4 and less than or equal to 10, The excitation power applied to the metal target is less than or equal to 10000W, and the radio frequency bias power applied to the base is less than or equal to 1000W.

In an optional solution, in the step 102, the flow rate of the third inert gas is less than or equal to 200 sccm; the RF bias power applied to the susceptor is greater than or equal to 40W and less than or equal to 100W; the reaction chamber The pressure is greater than or equal to 6mTorr, and less than or equal to 15mTorr.

Optionally, in the step 103, the flow rate of the fourth inert gas is less than or equal to 200 sccm, the flow rate of the process gas is less than or equal to 500 sccm; the flow ratio of the process gas to the fourth inert gas is greater than or equal to 4, and less than or equal to 10, the excitation power applied to the metal target is less than or equal to 10000W.

In an optional solution, in the step 3, the flow rate of the second inert gas is less than or equal to 200 sccm, and the RF bias power applied to the susceptor is greater than or equal to 150W and less than or equal to 400W.

In an optional solution, in the step 1, the vacuum degree of the reaction chamber is less than or equal to 5×10 ^-6 Torr; the temperature of the susceptor is greater than or equal to 400°C and less than or equal to 600°C.

In an optional solution, the metal target includes aluminum, titanium, hafnium or tantalum, or a compound of aluminum, titanium, hafnium or tantalum.

The beneficial effects of the present invention are:

In the preparation method of the metal compound thin film provided by the present invention, in step 2, the plasma formed by the first mixed gas is used to bombard the metal target, and at the same time, the radio frequency bias power is applied to the base, and the radio frequency bias power will be generated on the base A negative bias voltage is formed on the surface, which can optimize the direction of movement of ions in the plasma, so as to adjust the stress of the metal compound film when the metal compound film is formed on the wafer, so that the stress changes from tensile stress to compressive stress, and promotes the film to (002) generates a concentration of crystal orientations, which solves the problem of bending or even falling off of the film under force, thereby improving the reliability of the device.

Further, after the sputtering of the metal compound thin film is completed, a second inert gas is introduced into the reaction chamber, and a radio frequency bias power is applied to the susceptor. The plasma generated by the second inert gas can engrave the surface of the metal compound thin film. Corrosion can further change the stress from tensile stress to compressive stress, so as to further adjust the stress of the metal compound film.

The method of the present invention has other features and advantages that will be apparent from, or will be apparent from, the drawings and detailed description that follow, incorporated herein. Set forth in detail in the manner, these drawings and the detailed description together serve to explain certain principles of the present invention.

Description of drawings

The above and other objects, features and advantages of the present invention will become more apparent by describing the exemplary embodiments of the present invention in more detail with reference to the accompanying drawings.

Fig. 1 shows the structural diagram of the magnetron sputtering equipment that the embodiment of the present invention adopts;

Fig. 2 shows the flowchart of the preparation method of the metal compound film provided by the first embodiment of the present invention;

Fig. 3 shows the flowchart of the preparation method of the metal compound thin film provided by the second embodiment of the present invention;

Fig. 4 shows the flowchart of the preparation method of the metal compound film provided by the third embodiment of the present invention;

Fig. 5 shows the stress contrast figure of the metal compound film prepared according to two different embodiments of the present invention;

FIG. 6 shows a comparison chart of thin film XRD test results of metal compound thin films prepared according to the embodiment of the present invention and the prior art.

Detailed ways

The present invention will be described in more detail below. While the present invention has provided preferred embodiments, it should be understood that the invention can be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, or in a specific orientation. construction and operation, therefore, should not be construed as limiting the invention.

In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection. Connected, or integrally connected; it may be mechanically connected, may be directly connected, or may be indirectly connected through an intermediary. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

Fig. 1 shows a structural diagram of a magnetron sputtering device used in an embodiment of the present invention. Please refer to Fig. 1, this magnetron sputtering equipment comprises reaction chamber 14, and the top of this reaction chamber 14 is provided with target material 2, and above target material 2 is provided with vacuum cavity 15, and in this vacuum cavity 15 Filled with deionized water, used to cool the target 2, to prevent the target 2 from heating up due to heat release during the sputtering process. Moreover, a rotatable magnetron 1 is arranged in the vacuum cavity 15, and the magnetron 1 includes inner and outer magnetic poles with opposite polarities, which are used to improve the ionization rate of the gas in the sputtering process, thereby increasing the sputtering rate. Ejection deposition rate. In the reaction chamber 14 and below the target 2, a base 9 is provided, and a support 13 is provided on the base 9 for supporting the tray 8 carrying the wafer, so that the tray 8 is located above the base 9 ; A heating tube (not shown) is also provided on the base 9 for radiating heat toward the tray 8 and the wafer above it, so that the wafer can be heated to a preset temperature. Optionally, a cooling device is also provided in the base 9 for cooling the wafer. In addition, the base 9 is liftable, and it can rise from the film transfer position shown in Figure 1 to the process position. During this process, the base 9 will lift the pressure ring 5, so that the base 9, the upper inner Liner 3 and lower inner liner 4 form a closed sputtering environment. A library 10 is also provided on one side of the reaction chamber 14 for accommodating the baffle 7 , and the baffle 7 is used to move out of the library 10 during the pre-sputtering process and move to shield the wafer above. In addition, a vacuum pump system 12 is provided at the bottom of the reaction chamber 14 for evacuating the reaction chamber 14 so that the reaction chamber 14 can reach a higher degree of vacuum to meet the vacuum conditions required by the process.

The above-mentioned target material 2 is a metal target material, and the metal target material may be a pure metal or a metal compound. The target 2 is electrically connected to the excitation power supply, and the excitation power is used to load the excitation to the target 2, so that the target 2 forms a negative bias voltage relative to the grounded cavity (including the upper lining 3 and the lower lining 4), so that the sputtering The plasma is generated by discharging the jet gas (including N ₂ , Ar, O _{2 ,} etc.), the positively charged ions in the plasma are attracted to the target 2, and bombard the surface of the target 2, the sputtered metal atoms are mixed with the plasma Atoms (such as nitrogen atoms) react to form a metal compound and deposit on the surface of the wafer to form a metal compound film. Optionally, the above excitation power supply is, for example, a DC power supply for loading DC power, a pulsed DC power supply for loading pulsed DC power, or a combination of a DC power supply (or a pulsed DC power supply) and a radio frequency power supply.

The first embodiment of the present invention provides a method for preparing a metal compound film, please refer to Figure 2, the method for preparing the metal compound film includes:

Step 2: Introduce the first mixed gas of the first inert gas and the process gas into the reaction chamber, apply excitation power to the metal target in the reaction chamber, make the first mixed gas form plasma, and the plasma bombards the metal target material to form a metal compound film on the wafer; at the same time, RF bias power is applied to the base to adjust the stress of the metal compound film.

Optionally, the above-mentioned first inert gas includes, for example, argon, krypton, etc.; the process gas includes, for example, oxygen, nitrogen, and the like. In practical applications, the first inert gas and the process gas can be connected to the reaction chamber through flow meters.

In the above step 2, when the excitation power is applied to the metal target in the reaction chamber, under high pressure conditions, the first inert gas and the process gas are ionized and discharged to generate positively charged plasma, and the positively charged plasma Attracted by and bombards the metal target. When the energy of the plasma is high enough, the atoms on the surface of the metal target will escape and be deposited on the wafer, so as to achieve thin film deposition on the wafer surface. As the metal atoms escaping from the surface of the target combine with the atoms in the process gas to form metal compounds, they are deposited on the wafer surface and migrate on the wafer surface. At the same time, the RF bias power applied to the susceptor can promote the metal compounds on the wafer. The surface migrates to a certain direction, and the negative bias voltage formed on the surface of the base by the RF bias power can optimize the movement direction of the ions in the plasma, so as to adjust the stress of the metal compound film when the metal compound film is formed on the wafer, so that the stress The transition from tensile stress to compressive stress promotes the concentration of the film to the (002) crystal orientation, which solves the problem of bending or even falling off of the film under force, thereby improving the reliability of the device.

second embodiment

Please refer to Fig. 3, the preparation method of the metal compound thin film provided by the second embodiment of the present invention is an improvement made on the basis of the first embodiment above, specifically, the preparation method of the metal compound thin film also includes steps 1 and Step 2, the two are the same as the above-mentioned first embodiment, and will not be described again here.

After the above step 2, the preparation method also includes:

Step 3: Introduce a second inert gas into the reaction chamber, and apply radio frequency bias power to the susceptor, so that the second inert gas forms a plasma, and the plasma formed by the second inert gas conducts the surface of the metal compound film Etching to further adjust the stress of the metal compound film.

By feeding the second inert gas into the reaction chamber and applying radio frequency bias power to the susceptor, the plasma generated by the second inert gas can etch the surface of the metal compound film to etch and remove the lower mass on the film surface. At the same time, the stress can be further transformed from tensile stress to compressive stress to further adjust the stress of the metal compound film.

Taking the deposition of aluminum nitride film on the surface of the wafer as an example, after the above step 2, the above step 3 specifically includes: stop loading the excitation power and radio frequency bias power, and stop the introduction of inert gas and process gas, maintain the heating temperature and The position of the susceptor (process position) remains unchanged; a second inert gas (such as Ar) is introduced into the reaction chamber, and the flow rate of the second inert gas is less than or equal to 200 sccm, preferably greater than or equal to 100 sccm, and less than or equal to 200 sccm. The cold pump gate valve in the vacuum pump system is fully open to ensure that the impurity gas in the reaction chamber can be discharged. Applying radio frequency bias power to the base, optionally, the radio frequency bias power applied to the base is greater than or equal to 150W and less than or equal to 400W.

third embodiment

Please refer to Fig. 4, the method for preparing a metal compound thin film provided in the second embodiment of the present invention is an improvement made on the basis of the second embodiment above, specifically, the method for preparing a metal compound thin film also includes steps 1, Step 2 and Step 3 are the same as the above-mentioned second embodiment, and will not be described again here.

On this basis, the preparation method further includes at least one of step 101, step 102 and step 103. The preparation method will be described in detail below by taking the deposition of an aluminum nitride film on the surface of the wafer, and the preparation method including step 1, step 2 and step 3, and step 101, step 102 and step 103 as an example.

Specifically, according to the different deposited films, set suitable process conditions for the reaction chamber, put the tray of the wafer (such as silicon or silicon dioxide) carrying the film to be deposited into the reaction chamber, and place it on the base , that is, the top of the pillar placed on the base; adjust the temperature of the base to the temperature required by the process, for example, when depositing aluminum nitride film, the vacuum degree of the reaction chamber is less than 5×10-6Torr; the base The temperature is greater than or equal to 400°C and less than or equal to 600°C, such as 500°C. Optionally, when depositing non-conductive films such as aluminum nitride films, the excitation power loaded to the target can be pulsed DC power, which can avoid the formation of metal nitrides on the surface of the metal target due to the loading of DC power, Escape of metal atoms affecting the metal target.

In this embodiment, after step 1 and before step 2, it also includes:

Specifically, the tray and the wafer can be heated by the heating tube on the base to slowly raise the temperature to a preset temperature, the preset temperature is, for example, greater than or equal to 300° C. and less than or equal to 1000° C., preferably greater than or equal to 450° C. °C, and less than or equal to 800 °C, and maintained for 10s to 200s, preferably 20s to 60s. By heating the tray and wafer to a preset temperature, the water vapor of the tray and wafer and the organic impurities attached to the surface of the wafer can be removed under high temperature conditions.

In this embodiment, after step 101 and before step 2, it also includes:

Step 102: injecting a third inert gas into the reaction chamber, and applying radio frequency bias power to the susceptor, so that the third inert gas forms plasma, and the plasma formed by the third inert gas bombards the surface of the wafer, To remove impurities on the wafer surface.

Specifically, it may be as follows: maintain the heating temperature adopted in step 101, and feed a third inert gas, such as argon (Ar), into the reaction chamber. Optionally, the flow rate of the third inert gas is less than or equal to 200 sccm, preferably greater than or equal to 100sccm, and less than or equal to 200sccm. The chamber pressure is maintained in a relatively high pressure range, for example greater than or equal to 6 mTorr and less than or equal to 15 mTorr. Applying radio frequency bias power to the susceptor, the radio frequency bias power adopts a lower power range, so that ions in the plasma formed by the third inert gas can bombard the wafer surface to remove impurities and oxidation on the wafer surface substances, reduce wafer surface defects, and increase wafer surface activity. Optionally, the RF bias power applied to the base is greater than or equal to 40W and less than or equal to 100W. In addition, after the RF bias power applied to the base is stabilized, the process pressure (that is, the chamber pressure) can be reduced to about half of the original (such as greater than or equal to 3mTorr, and less than or equal to 8mTorr), and the formal process can be started. Pre-cleaning treatment process (ie, step 102).

In this embodiment, after step 102, step 103 is also included before step 2:

Move the baffle to the top of the covering wafer, pass the second mixed gas of the fourth inert gas and the process gas into the reaction chamber, apply excitation power to the metal target, make the second mixed gas form plasma, and perform a preliminary Sputtering process; after the gas flow and excitation power of the second mixed gas fed into the reaction chamber are stabilized (the stable index is that the fluctuation range of the gas flow is not greater than ±0.1%; the fluctuation range of the excitation power is not greater than ±0.1% %), remove the baffle from above the wafer, and keep the excitation power and the gas flow rate of the second mixed gas constant.

The above step 103 is a pre-sputtering process. Specifically, stop feeding the third inert gas, turn off the RF bias power applied to the base, adjust the base to the pre-sputtering station, move the baffle into the reaction chamber, and move it to cover the wafer ; Introducing a second mixed gas of a fourth inert gas (such as Ar) and a process gas (such as N ₂ ) into the reaction chamber, wherein the flow rate of the fourth inert gas is less than or equal to 200 sccm, preferably greater than or equal to 15 sccm, and less than or equal to 45 sccm , the flow rate of the process gas is less than or equal to 500 sccm, preferably greater than or equal to 90 sccm, and less than or equal to 300 sccm, the flow ratio of the process gas to the fourth inert gas is greater than or equal to 4, and less than or equal to 10, and the excitation power applied to the metal target is less than or equal to 10000W , preferably greater than or equal to 5000W, and less than or equal to 9000W, and maintain it for about 20s. After the reactive sputtering environment in the reaction chamber is stable, keep the excitation power and gas flow constant, keep the cold pump valve in the vacuum pump system fully open, remove the baffle from the wafer, and keep it for about 1s. Due to the unstable power and gas flow in the initial stage of sputtering in the reaction chamber, the quality of the formed metal compound film is poor. With the help of the above step 103, the metal compound film formed on the wafer can also meet higher quality requirements in the initial stage.

After the reactive sputtering environment in the reaction chamber is stable, the above step 2 is started. Specifically, the excitation power is maintained, the temperature and the process atmosphere are kept constant, and the susceptor is raised to the process position. The distance between the wafer and the target is, for example, greater than or equal to 30 mm and less than or equal to 80 mm, preferably greater than or equal to 40 mm and less than or equal to 60 mm. In this way, both the high growth rate of the film and the crystallization quality of the metal compound film can be guaranteed.

Applying a radio frequency bias power of less than or equal to 1000W to the base, preferably greater than or equal to 50W, and less than or equal to 300W, the higher the applied radio frequency bias power, the greater the tendency of the stress of the film to change from tensile stress to compressive stress. Based on this, When the tensile stress of the generated metal compound film is large, the tensile stress can be reduced by increasing the RF bias power, and when the tensile stress of the generated metal compound film is small, the tensile stress can be increased by reducing the RF bias power. At the same time, combined with the use of heating tubes in the base to heat the wafer, a relatively high process temperature can be maintained to ensure the crystallization quality of the metal compound film. The crystallization quality of the metal compound film changes positively with the process temperature. At the same time, the higher the process temperature, the greater the tensile stress of the metal compound film, which requires higher RF bias power to adjust the stress to transform it to compressive stress. . As the metal atoms (such as Al atoms) escaped from the target surface combine with the atoms (such as N atoms) in the plasma formed by the process gas, they are deposited on the wafer surface and migrate on the wafer surface, and the pedestal applies RF bias. The voltage power can promote the metal compound to migrate in a certain direction on the wafer surface, and the RF bias power makes the negative bias formed on the surface of the susceptor promote the concentration of the metal compound to the (002) growth crystal direction, thereby adjusting the stress of the metal compound film from tension to Stress changes to compressive stress. The crystallization quality of the metal compound film is better in the crystal direction (002). (002) is the arrangement orientation of the internal atomic structure of the material in solid state physics.

Optionally, in the above step 2, the deposition rate is controlled at 10-20 A/s until the thickness of the metal compound film reaches the thickness required by the process. The thickness of the metal compound thin film is generally controlled in the range of 200nm to 1300nm.

After completing the above step 3, stop applying RF bias power to the susceptor, stop gas flow, lower the process temperature, and pump the chamber to a high vacuum. The base is lowered from the process position to the transfer position, and the deposited wafer is moved out of the process chamber to complete the preparation of the metal compound film.

In the preparation method of the metal compound thin film provided by the embodiment of the present invention, in step 2, the metal target is bombarded with the plasma formed by the first mixed gas, and at the same time, the RF bias power is applied to the susceptor, and the RF bias power will be A negative bias voltage is formed on the base, which can optimize the direction of movement of ions in the plasma to adjust the stress of the metal compound film when the metal compound film is formed on the wafer, so that the stress changes from tensile stress to compressive stress, promoting The film is concentrated toward the (002) generation crystal direction, which solves the problem of bending or even falling off of the film under force, thereby improving the reliability of the device. Further, by feeding the second inert gas into the reaction chamber and applying radio frequency bias power to the susceptor, the plasma generated by the second inert gas can etch the surface of the metal compound thin film, and the stress can be further relieved from tension. The stress is converted to compressive stress to further adjust the stress of the metal compound film.

Fig. 5 shows a stress contrast diagram of aluminum nitride films prepared according to two different embodiments of the present invention. The abscissa is the applied radio frequency bias power (RF Bias), and the ordinate is the stress (Stress) of the aluminum nitride film, where the positive number is the tensile stress and the negative number is the compressive stress. The solid line in Fig. 5 shows that when adopting the method in the above-mentioned first embodiment to deposit and form the aluminum nitride film, the RF bias power (Bias Process) is applied to the base, and the magnitude of the applied RF bias power has a great influence on the aluminum nitride The influence of film stress; the dotted line in Fig. 5 shows that when adopting the method in the above-mentioned second embodiment to deposit and form aluminum nitride film, apply radio frequency bias power to base, after forming aluminum nitride film, continue to base The effect of RF bias power (Bias Process+Bias Etch) on the stress of aluminum nitride film. Comparing the solid line and the dotted line, it can be seen that compared with the method in the first embodiment, the stress in the second embodiment above can further transform the stress from the tensile stress to the compressive stress.

FIG. 6 shows a comparison chart of XRD test results of aluminum nitride thin films prepared according to the embodiment of the present invention and the prior art. The abscissa of FIG. 6 is the angle Angle ((002) crystal orientation), and the ordinate is the intensity of aluminum nitride. The dotted line in Fig. 6 indicates that when the aluminum nitride thin film is deposited and formed by the preparation method of the aluminum nitride thin film adopted in the prior art, no radio frequency bias power is applied to the base; the solid line in Fig. When the aluminum nitride thin film is deposited and formed by the preparation method of the aluminum nitride thin film, a radio frequency bias power is applied to the base. Comparing the solid line and the dashed line, it can be seen that after the RF bias power is applied to the base, the aluminum nitride film grows more towards the (002) crystal direction. As the common knowledge of those skilled in the art, when forming an aluminum nitride film, the While growing in the direction of the (002) crystal direction, some parts also grow in the direction of the (102) crystal direction. In order to improve the quality of the film, it is expected that the aluminum nitride film grows in the direction of the (002) crystal direction.

The above description takes the formation of aluminum nitride thin film as an example, it should be understood that the method of the present invention can also prepare other metal compound thin films, such as metal compound thin films for preparing titanium, hafnium or tantalum.

Having described various embodiments of the present invention, the foregoing description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and alterations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

Claims

A method for preparing a metal compound thin film, characterized in that the method comprises:

Step 1: Put the tray carrying the wafer to be deposited into the reaction chamber and place it above the base;

Step 2: Introduce a first mixed gas of a first inert gas and a process gas into the reaction chamber, apply excitation power to the metal target in the reaction chamber, and make the first mixed gas form a plasma, The plasma bombards the metal target to form a metal compound film on the wafer; at the same time, RF bias power is applied to the susceptor to adjust the stress of the metal compound film.
The method according to claim 1, further comprising after said step 2:

Step 3: Introduce a second inert gas into the reaction chamber, and apply radio frequency bias power to the susceptor, so that the second inert gas forms a plasma, and the plasma formed by the second inert gas is The surface of the metal compound film is etched to further adjust the stress of the metal compound film.
The method according to claim 1, characterized in that, after the step 1 and before the step 2, further comprising:

Step 101: heating the tray and the wafer to a preset temperature to remove moisture from the tray and the wafer and organic impurities attached to the surface of the wafer.
The method according to claim 3, characterized in that, after the step 101 and before the step 2, further comprising:

Step 102: Flowing a third inert gas into the reaction chamber, and applying radio frequency bias power to the susceptor, so that the third inert gas forms a plasma, and the plasma formed by the third inert gas bombarding the surface of the wafer to remove impurities on the surface of the wafer.
The method according to claim 4, characterized in that, after the step 102 and before the step 2, further comprising:

Step 103: Move the baffle to cover the wafer, pass the second mixed gas of the fourth inert gas and the process gas into the reaction chamber, apply excitation power to the metal target, and make the The second mixed gas forms plasma and performs a pre-sputtering process; after the gas flow rate of the second mixed gas and the excitation power introduced into the reaction chamber are stabilized, the baffle is removed from the crystal The upper part of the circle is removed, and the excitation power and the gas flow rate of the second mixed gas are kept constant.
The method according to claim 1, wherein in the step 2, the flow rate of the first inert gas is less than or equal to 200 sccm, and the flow rate of the process gas is less than or equal to 500 sccm; the process gas and the first The flow ratio of the inert gas is greater than or equal to 4 and less than or equal to 10, the excitation power applied to the metal target is less than or equal to 10000W, and the radio frequency bias power applied to the base is less than or equal to 1000W.
The method according to claim 4, characterized in that, in the step 102, the flow rate of the third inert gas is less than or equal to 200 sccm; the RF bias power applied to the susceptor is greater than or equal to 40W and less than equal to 100W; the pressure of the reaction chamber is greater than or equal to 6mTorr and less than or equal to 15mTorr.
The method according to claim 5, characterized in that, in the step 103, the flow rate of the fourth inert gas is less than or equal to 200 sccm, and the flow rate of the process gas is less than or equal to 500 sccm; the process gas and the first The flow ratio of the four inert gases is greater than or equal to 4 and less than or equal to 10, and the excitation power applied to the metal target is less than or equal to 10000W.
The method according to claim 2, wherein in the step 3, the flow rate of the second inert gas is less than or equal to 200 sccm, and the RF bias power applied to the susceptor is greater than or equal to 150 W, and is less than or equal to 400W.
The method according to claim 1, wherein in the step 1, the vacuum degree of the reaction chamber is less than or equal to 5×10 -6 Torr; the temperature of the susceptor is greater than or equal to 400°C, and is less than or equal to 600°C.
The method according to any one of claims 1-10, wherein the metal target material comprises aluminum, titanium, hafnium or tantalum, or a compound of aluminum, titanium, hafnium or tantalum.