CN215517601U

CN215517601U - Preparation equipment of AlN film with adjustable refractive index

Info

Publication number: CN215517601U
Application number: CN202121409192.3U
Authority: CN
Inventors: 唐云俊; 王昱翔; 周虹玲; 周东修
Original assignee: Zhejiang Aiweipu Technology Co ltd
Current assignee: Zhejiang Aiweipu Technology Co ltd
Priority date: 2021-06-24
Filing date: 2021-06-24
Publication date: 2022-01-14
Anticipated expiration: 2031-06-24

Abstract

The utility model discloses preparation equipment of an AlN thin film with adjustable refractive index, which comprises a process cavity, wherein the process cavity is provided with a process gas inlet and a vacuum suction port, and the process gas inlet is connected with a nitrogen pipeline and an argon pipeline.

Description

Preparation equipment of AlN film with adjustable refractive index

Technical Field

The utility model belongs to the technical field of magnetron sputtering and reactive sputtering, and particularly relates to equipment for preparing an aluminum nitride (AlN) film with controllable magnetron sputtering, reactive sputtering and refractive index.

Background

The nitride film has the characteristics of high breakdown electric field, high thermal conductivity, high electron saturation velocity, high radiation resistance and wide forbidden band width. And because the nitride film has the characteristics of wide energy gap direct energy band structure, high efficiency visible light and ultraviolet light emission, the nitride film is an ideal material for manufacturing blue-green Light Emitting Diodes (LEDs) and Laser Diodes (LDs), and has good application prospect in the aspects of short-wavelength light emission, light display devices and full-color light devices. Particularly, aluminum nitride has high thermal conductivity, high hardness, good dielectric property, acoustic property and chemical stability, and is widely applied to the fields of communication, power semiconductor devices and various microelectronic devices such as machinery, optics, photoelectric devices, piezoelectric devices, surface acoustic wave devices (SAW), thin film bulk acoustic wave devices (FABAR) and the like.

There are various methods for preparing aluminum nitride (AlN) thin films, such as IBD (ion Beam deposition) method using Ar (or N)₂Bombarding AlN (or Al target) by Ar ion beam, and depositing (reacting and depositing) an aluminum nitride (AlN) film; preparing an aluminum nitride (AlN) film by Atomic Layer Deposition (ALD); preparing an aluminum nitride (AlN) film by a PECVD (plasma Enhanced Chemical Vapor deposition) method; preparing an aluminum nitride (AlN) film by magnetron reactive sputtering.

Among them, the magnetron sputtering method is widely and most commonly used in the preparation of microelectronic devices due to the comprehensive factors of high deposition rate, good film uniformity, excellent film quality, simple process, low cost, etc.

Optical thin film devices are used more and more widely and in more and more types, for example, coated glasses, curtain wall glass, optical filters, ITO object films, cold mirrors, stage lighting optical filters, devices in the field of optical communication and optical fiber thin film devices, infrared films and projection displays, liquid crystal projection display systems, and the like.

Antireflection film is also called antireflection film, and is one of the most widely used types of optical films, and is used for reducing reflection on the surface of an optical device and increasing light transmission. The reflective film is also a common film layer in an optical system, and functions to reflect most or nearly all of incident light to achieve the purposes of changing direction or converging light energy. In designing and preparing the antireflection film and the reflection film, strict requirements are made on the accuracy of the refractive index of the film so as to achieve the purposes of antireflection and reflection light, and therefore, in the preparation process of the antireflection film and the reflection film, the refractive index of the film is required to be accurately regulated and controlled.

Therefore, it is highly desirable to provide a magnetron sputtering method for preparing an aluminum nitride (AlN) thin film with a precisely controllable refractive index.

SUMMERY OF THE UTILITY MODEL

Aiming at the defects of the prior art, the utility model provides a method which can regulate and control the refractive index of aluminum nitride (AlN) by accurately regulating and controlling the content of nitrogen in process gas in reactive sputtering so as to meet the design requirement.

In order to achieve the above purpose, the present invention provides a technical solution comprising the following equipment and processes: the utility model provides a preparation equipment of refracting index adjustable AlN film, includes the technology cavity, be provided with target and substrate platform in the technology cavity, the substrate platform passes through the wire and connects the matching network, the matching network passes through the wire and connects radio frequency power supply, be provided with process gas import and vacuum suction inlet on the technology cavity, vacuum suction inlet is connected with the vacuum pump, and process gas import is connected with nitrogen gas pipeline and argon gas pipeline above-mentioned gas flowmeter that is provided with.

Furthermore, a back plate is arranged on the process cavity, the target is connected to the back plate, and a cooling pipeline is arranged in the back plate.

The target is further connected with a target power supply through a back plate, and the target power supply is a direct current power supply, a pulse direct current power supply, a radio frequency power supply or an HIPIMS power supply.

Furthermore, a magnetron is arranged behind the back plate.

The conveying device is characterized by further comprising a conveying cavity and an uploading cavity, wherein a mechanical arm is arranged in the conveying cavity, a first vacuum valve is arranged between the uploading cavity and the conveying cavity, a second vacuum valve is arranged between the conveying cavity and the process cavity, and a sealing door is arranged on the uploading cavity.

Compared with the prior art, the utility model has the beneficial effects that:

by finely regulating the relative content of the flow of the nitrogen in the reaction gas in the reactive sputtering process, the nitrogen content and the structure in the formed aluminum nitride (AlN) film are further finely regulated, so that the refractive index of the aluminum nitride (AlN) film can be finely regulated.

Drawings

FIG. 1 is a schematic diagram of a hysteresis loop;

FIG. 2 is a schematic structural view of a process chamber according to the present invention;

FIG. 3 is a schematic structural view of a process chamber, a transport chamber and an upload chamber of the present invention;

FIG. 4 is a graph showing the hysteresis loop obtained in the experimental case of the present invention;

FIG. 5 shows the relationship between the refractive index (633nm) and uniformity of AlN thin films obtained in the experimental case of the present invention and the nitrogen content in the process gas.

Reference numerals: 1. a target power supply; 2. a substrate stage; 3. a matching network; 4. a radio frequency power supply; 5. a substrate; 6. a process chamber; 7. a transport cavity; 8. an uploading cavity; 10. a manipulator; 11. a first vacuum valve; 12. a second vacuum valve; 13. an argon gas pipeline; 14. a nitrogen gas pipeline; 15. and (4) vacuum suction.

Detailed Description

In the description of the present invention, it should be noted that, for the terms of orientation, such as "central", "lateral (X)", "longitudinal (Y)", "vertical (Z)", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc., indicate that the orientation and 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, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and should not be construed as limiting the specific scope of the present invention.

Furthermore, if the terms "first" and "second" are used for descriptive purposes only, they are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features. Thus, a definition of "a first" or "a second" feature may explicitly or implicitly include one or more of the features, and in the description of the utility model, "a number" or "a number" means two or more unless explicitly specified otherwise.

As shown in fig. 1, the magnetron reactive sputtering generally has a "hysteresis loop" effect, that is, the current or voltage of the target changes with the flow of the reactive gas to generate a sudden change; and the voltage/current change of the gradually increasing section of the gas flow is not overlapped with the voltage/current change of the gradually decreasing section of the gas flow, so that a 'hysteresis loop' is formed. This is due to the different escape voltages of the sputtered material at different reactant gas flow rates on the surface of the metal target. Under the condition of the reaction gas flow less than the point A, metal materials are mainly sputtered, the target material voltage is higher, the sputtering rate is also high, and the sputtering mode is called as a metal mode; under the condition of the reaction gas flow rate larger than the point B, oxide materials are mainly sputtered, the target material voltage is lower, the sputtering rate is also low, and the sputtering mode is called as a poisoning mode; between points A-B, metal and oxide mixed materials are sputtered, and the material is called as a transition mode; wherein, the B-C point area can form a stable oxide film and has higher sputtering rate.

While reaction-deposited aluminum nitride (AlN) films are typically selected in a "poisoned mode". This is due to:

1. the reaction deposited aluminum nitride (AlN) film does not have a significant arcing phenomenon and can form a more stable sputtering process relative to the poisoned mode.

2. The sputtering rate in this mode is not much reduced, typically 20-50% lower, than the rate in the transition mode; meanwhile, the aluminum nitride (AlN) film required by the optical device is generally only dozens of nanometers, and the sputtering rate in the poisoning mode can well meet the productivity requirement of the process.

3. Meanwhile, the content of reaction gas nitrogen in the process gas is changed, the structure and the components of the aluminum nitride (AlN) film can be finely adjusted, and further the optical parameters of the film can be accurately regulated and controlled.

The utility model provides a preparation equipment of refracting index adjustable AlN film, includes technology cavity 6, be provided with target and substrate platform 2 in the technology cavity 6, substrate platform 2 passes through wire connection matching network 3, matching network 3 passes through wire connection radio frequency power supply 4, be provided with process gas import and vacuum suction port 15 on the technology cavity 6, vacuum suction port 15 is connected with the vacuum pump, and process gas import is connected with nitrogen gas pipeline 14 and argon gas pipeline 13 the above-mentioned gas flowmeter that is provided with of.

The target is an aluminum (Al) target, which is generally circular, but may be other shapes. The diameter of the circle is usually between 4 and 20 inches, and the thickness is usually between 2 and 10 mm.

Wherein the process gas inlet is connected with a nitrogen and argon pipeline 13, and the nitrogen and the argon are respectively controlled by a gas flowmeter, so that the gas flow entering the process cavity 6 can be respectively and accurately regulated. The control range of the gas flowmeter is usually between 0sccm and 200sccm, and the accuracy can reach 0.1 sccm.

The vacuum suction port 15 of the process chamber 6 is connected to a vacuum pump, which, when operating, vacuums the process chamber 6. The cavity background vacuum is generally less than 2 ×<10^-7Torr。

During the film deposition process, a bias electric field can be applied to the substrate 5 by the radio frequency power supply 4 connected with the matching network 3, so as to improve the structure and the performance of the film.

The process chamber 6 is provided with a back plate, the target is connected to the back plate, a cooling pipeline is arranged in the back plate, the target is an aluminum (Al) target, the cooling pipeline can be cooled by water, the target is connected with a target power supply 1 through the back plate, and the target power supply 1 can be a direct current power supply (DC), a pulse direct current power supply (PDC), a radio frequency power supply 4(RF) or an HIPIMS and other power supplies; the target power supply 1 can apply energy to the target to form an electric field, so that process gas in the cavity is ionized to form plasma, the surface of the target is bombarded to form sputtering, and the power of the applied power supply is usually between dozens of watts and dozens of kilowatts in the film deposition process.

The embodiment preferably further comprises a magnetron which is arranged behind the back plate and is parallel to the back surface of the target, wherein the magnetron can be static or moving, and the moving magnetron generally rotates around the central line of the target; the magnetron is provided with magnets, usually with magnets of opposite polarities which are adjacently paired, and the generated magnetic field forms a magnetic field distribution on the surface of the target, controls the moving area of electrons and ions on the surface of the target, and improves the plasma concentration and the film deposition rate, and the rotation speed of the magnetron can be 30-60 RPM, usually <200 RPM.

The preferred cavity 7 and upload the cavity 8 of still including transporting of this embodiment, it is provided with manipulator 10 in the cavity 7 to transport, it is provided with first vacuum valve 11 to upload between cavity 8 and the cavity 7 to transport, is provided with second vacuum valve 12 between cavity 7 and the technology cavity 6 transports, is provided with the sealing door on uploading the cavity 8.

A preparation method of an AlN thin film with adjustable refractive index comprises the following process steps:

s1: compiling a hysteresis loop menu: determining the power of a target power supply 1, the pressure of process gas, the flow of argon, the change of nitrogen flow, process time and bias power or voltage of a radio frequency power supply 4;

s2: uploading a substrate 5, and running the hysteresis loop menu;

when the substrate 5 is loaded, firstly, the sealing door is opened to place the substrate 5 in the loading cavity 8, and the loading cavity 8 is vacuumized; the first vacuum valve 11 is opened, the substrate 5 is transported into the transport chamber 7 by the robot 10, the first vacuum valve 11 is closed, the second vacuum valve 12 is opened, the substrate 5 is transported onto the substrate table 2 of the process chamber 6 by the robot 10, and then the second vacuum valve 12 is closed.

S3: downloading a substrate 5 and drawing a hysteresis loop menu;

when the substrate 5 is downloaded, the second vacuum valve 12 is opened, the manipulator 10 takes the substrate 5 out of the process cavity 6 into the transport cavity 7, the second vacuum valve 12 is closed, the first vacuum valve 11 is opened, the manipulator 10 takes the substrate 5 out of the transport cavity 7 into the uploading cavity 8, the first vacuum valve 11 is closed, and after the uploading cavity 8 is vacuumized to the atmospheric pressure, the sealing door is opened, and the sample is taken out.

S4: determining the nitrogen flow of the reactive sputtering aluminum nitride according to the hysteresis loop so that the reactive sputtering process is in a poisoning mode, and compiling a process menu according to the nitrogen flow;

s5: uploading a substrate 5 and running a process menu;

s6: downloading a substrate 5, and measuring the optical parameters of the aluminum nitride film obtained by sputtering under the nitrogen flow;

s7: selecting whether to adjust the process parameters according to whether the optical parameters reach the standard, and if the optical parameters, such as the measured refractive index, do not reach the standard, entering step S8; and if the optical parameters reach the standard, the requirements are met, and the process is finished.

S8: fine-adjusting the nitrogen flow to form a new process menu, wherein the variation is usually 0.2-1 sccm or N is used when adjusting the nitrogen flow₂/(Ar+N₂) The variation is about 5 percent, and simultaneously, the new process is still in a poisoning mode; steps S5-S7 are repeated.

As shown in Table 1, there are several cases of running the specific implementation of the process steps S2-S4.

Table 1:

case(s)	Power of target power supply 1	Pressure of process gas	N₂/(Ar+N₂)	Refractive index n (633)	n(633)Std％
							(W)	(mT)	％
1	3000	2	50％	2.084	0.28％
						2	3000	2	57％	2.129	0.36％
3	3000	2	60％	2.135	0.36％
						4	3000	2	63％	2.120	0.25％

As can be seen from table 1, fig. 4 and fig. 5:

under the conditions of the experimental case, the poisoning point of the reactive sputtering is approximately 45% of the nitrogen content of the total process gas content.

Different nitrogen contents are selected, and the nitrogen content is 50-63% of the total process gas content, so that the reactive sputtering is in a poisoning mode.

During this period, the value of the refractive index n gradually increases with the increase of the nitrogen content, and reaches a peak value of n 2.135 when the content is 63% of the total process gas content, and gradually decreases to n 2.120 when the nitrogen content further increases.

Meanwhile, the refractive index n value of the section is less than 0.4% in uniformity, which shows that the AlN thin film preparation process in the experimental case intervals is excellent and stable in performance.

On the other hand, it can be found that the refractive index n of the AlN thin film can be precisely adjusted by adjusting the content of nitrogen in the total process gas, conversely.

The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the utility model may occur to those skilled in the art without departing from the principle of the utility model, and are considered to be within the scope of the utility model.

Claims

1. The preparation equipment of the AlN thin film with the adjustable refractive index is characterized in that: the technical cavity is internally provided with a target and a substrate table, the substrate table is connected with a matching network through a wire, the matching network is connected with a radio frequency power supply through a wire, the technical cavity is provided with a technical gas inlet and a vacuum suction port, the vacuum suction port is connected with a vacuum pump, the technical gas inlet is connected with a nitrogen pipeline and an argon pipeline, and the nitrogen pipeline and the argon pipeline are provided with a gas flow meter.

2. The apparatus for preparing an AlN thin film with adjustable refractive index according to claim 1, wherein: the process cavity is provided with a back plate, the target is connected to the back plate, and a cooling pipeline is arranged in the back plate.

3. The apparatus for preparing an AlN thin film with adjustable refractive index according to claim 2, wherein: the target is connected with a target power supply through a back plate, and the target power supply is a direct current power supply, a pulse direct current power supply, a radio frequency power supply or an HIPIMS power supply.

4. The apparatus for preparing an AlN thin film with adjustable refractive index according to claim 3, wherein: a magnetron is arranged behind the back plate.

5. The apparatus for preparing an AlN thin film with adjustable refractive index according to claim 4, wherein: the manipulator is arranged in the transporting cavity, a first vacuum valve is arranged between the uploading cavity and the transporting cavity, a second vacuum valve is arranged between the transporting cavity and the technological cavity, and a sealing door is arranged on the uploading cavity.