VOx film steady-state growth gas inlet device based on quick response gas control

Abstract

The invention relates to the technical field of sputter coating, in particular to a VOx thin film steady-state growth gas inlet device based on quick response gas control, which is used for injecting reaction gas into a reaction cavity in a VOx thin film sputtering system, a base and a heater arranged in the base are arranged in the reaction cavity, the gas inlet device comprises a reaction gas conveying channel and a gas inlet hole, the conveying channel is connected with an external gas source and conveys reaction gas to the reaction cavity, and the conveying channel is arranged below the base; the air inlet holes are formed in the base table top and communicated with the conveying channel, and the distribution of the air inlet holes in the base table top is that the density of an edge area below a wafer is larger than that of a central area. According to the invention, the inherent deposition non-uniformity of the edge and the center of the wafer is compensated through the non-uniform air inlet holes, so that the uniformity of the film is improved on the whole; the oxygen partial pressure adjusting rate is increased through a shortened gas conveying path, the target voltage fluctuation range is narrowed, and finally steady-state control is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sputtering coating, in particular to a VOx thin film steady-state growth gas inlet device based on rapid response gas control. BACKGROUND

[0002] The reactive magnetron sputtering technology is one of the important means for preparing VOx functional thin films. In this technology, a reaction gas (such as oxygen) is introduced into a reaction chamber, and the sputtered target atoms are chemically reacted with the reaction gas on the surface of a substrate (such as a wafer) through plasma bombardment of a metal target, and then deposited into a film.

[0003] In the prior art, the introduction method of the reaction gas and the gas control have a decisive influence on the uniformity of the thin film. The common gas supply methods at present mostly adopt direct introduction and use of a simple oxygen inlet ring. These methods are prone to cause uneven distribution of the reaction gas in the chamber, and thus cause large differences in the in-plane distribution of the deposited thin film thickness, chemical composition, and sheet resistance, etc., which is difficult to meet the stringent requirements of high-performance devices on the uniformity of the thin film.

[0004] To solve the problem of thin film uniformity caused by uneven gas distribution, some improvement schemes are proposed in the prior art. For example, patent publication CN117385331A discloses a device for improving the uniformity of vanadium dioxide thin films. The device is provided with a plurality of gas pipes arranged circumferentially in the inner shell of the reaction chamber, and the length of the gas pipes or corrugated pipes is selected to adjust the position of the gas outlet end. At the same time, different angle bends are installed at the gas outlet end to adjust the gas outlet direction, so as to improve the uniformity of the oxygen distribution in the working space of the chamber.

[0005] On the other hand, in terms of gas control, a gas closed-loop feedback control mechanism based on sputtering voltage feedback is usually adopted. The control system utilizes the correlation between the "target poisoning" effect and the sputtering voltage. When the oxygen is excessive, a high-resistance V2O5 insulating layer is formed on the surface of the target, resulting in an increase in the sputtering voltage. Conversely, when the oxygen is insufficient, the surface of the target returns to its metallic conductive properties, and the voltage decreases. Based on this characteristic, the control system monitors the voltage changes in real time, and adjusts the oxygen flow through feedback to maintain the stability of the reaction process.

[0006] However, the inventors found that although the solutions such as CN117385331A optimize the gas input position and direction by adding a gas pipe structure in the cavity, improving the gas distribution uniformity, but at the same time inevitably prolongs the gas path, aggravates the inherent response lag and hysteresis effect of the gas control unit. There is a long mechanical and gas path transmission delay from the issuance of the regulation instruction to the actual entry of the gas into the cavity and the action on the plasma state, resulting in overshoot or undershoot in the reaction gas flow regulation, and the process state is difficult to stabilize quickly. In addition, the too long gas path further amplifies the hysteresis characteristics of the system, causing the film characteristics to vary significantly with the gas flow history under the same oxygen partial pressure, and aggravating the process debugging difficulty and the film uniformity. SUMMARY

[0007] The application provides a VOx film steady-state growth gas inlet device based on fast response gas control, aiming to shorten the reaction gas circuit and improve the film uniformity.

[0008] To solve the above problems, the application provides a VOx film steady-state growth gas inlet device based on fast response gas control, which adopts the following technical scheme: The VOx film steady-state growth gas inlet device based on fast response gas control is used to inject reaction gas into a reaction cavity in a VOx film sputtering system, and the reaction cavity is provided with a pedestal and a heater arranged inside the pedestal. The gas inlet device comprises: A reaction gas delivery channel connected with an external reaction gas source, which delivers reaction gas to the reaction cavity, and the delivery channel is arranged below the pedestal; A plurality of gas inlet holes arranged on the pedestal table and communicated with the delivery channel, and the distribution of the plurality of gas inlet holes on the pedestal table is that the density of the gas inlet holes at the lower edge region of the wafer is greater than that at the center region.

[0009] The gas inlet holes below the wafer are designed in a differentiated layout mode, specifically, the density of the gas inlet holes at the periphery is greater than that at the center. The gas flow at the edge of the wafer is greater than that at the center, and the convection of the edge gas is enhanced, so as to improve the temperature of the edge region by using the "convection heat transfer" effect. The high temperature promotes the increase of the oxygen precipitation amount of the edge film, and then reduces the sheet resistance (Rs) of the edge film. The inherent deposition non-uniformity of the wafer edge and center is compensated, so as to improve the film uniformity as a whole (originally, the non-uniform distribution of the high Rs at the edge and the low Rs at the center is artificially raised by raising the temperature at the edge and reducing the Rs at the edge, so that the Rs distribution of the whole wafer becomes uniform).

[0010] The gas inlet holes are distributed on the base mesa such that the density of the edge region is greater than that of the center region, thereby achieving a delicate gas-heat-electricity coupling regulation. The setting makes the gas flow into the edge region of the wafer significantly greater than that of the center region, and the enhanced gas flow strengthens the convective heat transfer of the edge region. In a typical reactive sputtering process (the substrate table is heated), this results in an unexpected effect: the higher flow rate and higher temperature of the reactive gas play a stronger "warming" role on the wafer edge, making the edge region temperature higher than the center region, which actively creates a controllable temperature gradient.

[0011] The artificially introduced temperature gradient significantly changes the local chemical reaction of film deposition. High temperature promotes the increase of oxygen precipitation in the edge film, forming a metal-rich vanadium oxide phase, which has a lower resistivity, thereby reducing the sheet resistance (Rs) of the edge film.

[0012] By controlling the temperature field through non-uniform hole distribution, the chemical composition and phase structure of the film in different regions of the wafer are actively regulated, and ultimately the distribution of the sheet resistance (Rs) is tailored. This is a cross-disciplinary, high-level solution that controls the thermal effect (temperature) through physical means (hole distribution) to ultimately solve the electrical problem (Rs uniformity).

[0013] The hysteresis effect and uniformity problem of reactive sputtering is a "big difficult" problem. The mainstream solution in the industry is to improve active control (such as feedforward control, faster valves, PID algorithm optimization, etc.) or form a uniform gas flow distribution above the wafer. This solution provides a completely different technical path: a passive, hardware structure-based solution that does not "hard fight" with the control loop, but instead takes a different approach and even reverses the process, actively introducing a controllable, non-uniform gas flow distribution, which uses this non-uniformity to compensate for the non-uniformity caused by another physical process (deposition / reaction). It also cleverly uses the series of physical and chemical effects of gas flow, convective heat transfer, and film oxygen precipitation.

[0014] It is generally believed that increasing the gas flow will bring more reactive gas, which may cause the film resistivity to decrease (due to increased metal phase or doping) or increase (due to more complete oxidation), with uncertain results. However, the present invention controls the local gas flow and flow rate through "non-uniform hole opening", changes the local convective heat transfer coefficient, increases the local temperature, actively controls the gas flow and temperature distribution of the wafer, and ultimately makes the Rs distribution uniform across the wafer surface.

[0015] As a preferred technical solution of the present invention, the gas inlet holes are arranged as blind holes, and the bottoms of the blind holes are connected to the conveying channel through transverse communication holes.

[0016] As a preferred technical solution of the present application, the gas inlet holes are arranged in the form of concentric circles, and the distribution density of the gas inlet holes increases and / or the hole diameter increases from the innermost circle to the outermost circle.

[0017] As a preferred technical solution of the present application, the gas inlet holes in different concentric circle regions have different depths.

[0018] As a preferred technical solution of the present application, the number of gas inlet holes per unit area in the edge region of the base platform is 1.5-3 times that in the center region.

[0019] As a preferred technical solution of the present application, at least a part of the delivery channel is integrated inside the heater. The delivery channel integrated inside the heater is a heating channel. By integrating part of the delivery channel inside the heater, not only the device space is saved, but also the heat conduction efficiency is enhanced, ensuring that the reaction gas reaches the required process temperature before entering the reaction cavity.

[0020] As a preferred technical solution of the present application, a pneumatic valve is provided upstream of the heater in the direction of gas flow. In the direction of gas flow in the delivery channel, the pneumatic valve is provided upstream of the heater, which can achieve rapid and accurate control of the flow of reaction gas. This ensures that the reaction gas can be turned on or off or adjusted before it enters the heating area, thereby improving the dynamic response capability of the process. This is particularly suitable for scenarios that require rapid adjustment of gas supply.

[0021] As a preferred technical solution of the present application, a control unit is further included, which controls the pneumatic valve provided upstream of the heater to adjust the flow of reaction gas into the delivery channel inside the heater according to the voltage fluctuation of the target surface.

[0022] As a preferred technical solution of the present application, the pneumatic valve is a fast-response valve.

[0023] More preferably, the fast-response valve is a piezoelectric valve or a voice coil valve.

[0024] As a preferred technical solution of the present application, the reaction gas delivery channel includes a first branch and a second branch that are independent of each other, the first branch supplies gas to the gas inlet holes in the center region, the second branch supplies gas to the gas inlet holes in the edge region, and a valve element that can independently adjust the flow rate is provided on each of the first branch and the second branch. This realizes fine zoned control of the reaction gas delivery process. By dividing the delivery channel into a first branch and a second branch that are independent of each other, corresponding to the gas inlet holes in the center region and the edge region respectively, and providing a valve element that can independently adjust the flow rate on each branch, the gas flow distribution in different regions can be accurately adjusted according to actual process requirements.

[0025] As a preferred technical solution of the present application, the gas inlet device is suitable for a magnetron sputtering system of a vanadium oxide film.

[0026] The beneficial effects are: 1. The gas inlet device cancels the long gas nozzle gas inlet structure, sets the gas inlet holes on the base mesa below the wafer, and sets the density distribution of the gas inlet holes on the base mesa as non-uniform gas holes with the density of the edge gas inlet holes being greater than that of the central area. On the one hand, the gas delivery path is shortened, and the time required for the gas control loop to respond is also shortened, reducing the influence of the response lag and hysteresis effect existing in the traditional long path gas control, and improving the rapid and stable control of the process state; on the other hand, by means of the non-uniform distribution of the gas inlet holes on the base mesa, the preheated and controllable distribution of the reaction gas is delivered to the base surface to compensate for the difference in reaction gas consumption rate in different areas of the wafer surface, so as to obtain a vanadium oxide film with uniform composition and sheet resistance. That is, more air is supplied to the edge area of the wafer, the convection is strong, the temperature of the edge area rises higher than that of the central area, and the high temperature makes the oxygen precipitation amount of the film in the edge area higher than that in the central area, so the Rs of the edge area is significantly reduced.

[0027] 2. The heater is used to preheat the gas in the delivery channel to shorten the thermal response time of the reaction gas from flow regulation to actual participation in the sputtering reaction. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a sectional view of the reaction chamber and the part of the delivery channel connected with the base; Figure 2 It is a structural schematic view of the base and part of the delivery channel; Figure 3 It is a sectional view of the base (the sectional view of the uppermost layer of transverse communication holes); Figure 4 It is a schematic view of the oxygen gas control loop in the reaction sputtering process of the traditional long gas nozzle structure (hereinafter referred to as before improvement); Figure 5 It is a schematic view of the oxygen gas control loop in the reaction sputtering process of the present application; Figure 6 It is a schematic view of the characteristic curve of the change of the target surface voltage with time in the reaction sputtering process before improvement; Figure 7 It is a schematic view of the characteristic curve of the change of the target surface voltage with time in the reaction sputtering process of the present application; Figure 8 It is a distribution map of the wafer surface resistance value before improvement; Figure 9 It is a distribution map of the wafer surface resistance value of the present application.

[0029] Explanation of reference signs: 1, reaction cavity; 2, base; 21, gas inlet hole; 22, communication hole; 3, conveying channel. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It should be known by those skilled in the art that the embodiments described below are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0031] The structure of a conventional reactive sputtering system for growing a VOx film includes a reaction cavity, a sputtering power supply, and a vacuum pumping system, a wafer conveying system and a gas control unit connected to the reaction cavity respectively. The gas control unit undertakes the key function of accurately supplying reaction gas and can strictly control the content of reaction gas in the reaction cavity.

[0032] A common gas control unit establishes a closed-loop control feedback mechanism by collecting sputtering voltage: the system uses the correlation between the "target poisoning" phenomenon and voltage - when oxygen is excessive, an insulating V2O5 layer is formed on the surface of the vanadium target, resulting in an increase in voltage (the resistivity of metallic vanadium is about 25 μΩ·cm, while the resistivity of V2O5 is as high as 10 10 Ω·cm, and the insulating layer causes the equivalent impedance of the plasma interface to soar, requiring a higher voltage to maintain the discharge, so the power supply must increase the voltage); on the contrary, when oxygen is insufficient, the deposition of metallic vanadium reduces the voltage. Based on this characteristic, the PLC continuously compares the actual measured voltage of the reaction cavity with the expected value, and dynamically adjusts the oxygen flow according to the comparison result, so as to stabilize the sputtering at the target reaction state. The core value of this voltage steady-state control is that it can indirectly maintain the dynamic balance of vanadium-oxygen reaction and effectively avoid the out-of-control of oxygen partial pressure.

[0033] The above gas control mechanism can be directly applied to the magnetron sputtering preparation of vanadium oxide film: using metallic vanadium as target material, the oxygen flow is precisely controlled to change the target voltage, and then the vanadium oxide film is generated on the substrate. The gas delivery path is specifically represented as: oxygen is controlled by the chain control of gas cylinder→first pneumatic valve→vacuum valve (pressure regulating valve)→flow meter→second pneumatic valve, and finally enters the reaction zone through multiple gas nozzles uniformly distributed inside the cavity. After oxygen participates in the reaction, the oxygen concentration affects the change of the target surface voltage, and the change of the target surface voltage triggers the fluctuation of the power supply voltage, and the PLC immediately adjusts the gas flow meter in the opposite direction according to the voltage monitoring value, and the flow meter controls the oxygen input concentration, forming a closed-loop negative feedback gas control loop.

[0034] However, the long-path feedback mechanism of the traditional gas control loop causes a double-coupling problem in actual operation: Response lag: due to the actual feedback path of the device is too long, there is mechanical delay, unable to respond to dynamic response process in real time. When the system detects that the oxygen partial pressure deviates from the target (such as voltage reduction indicating hypoxia), the adjustment instruction needs to be transmitted through the long chain of gas cylinder -> pressure regulating valve -> flow meter -> pneumatic valve -> gas nozzle, that is, from oxygen flow adjustment to plasma state change needs to wait for time, during which the local area may first generate conductive VO phase due to transient hypoxia, and then cause excessive oxygen compensation to form high resistance V2O5 due to oxygen accumulation, the response lag makes the plasma in a state of shock and out of control.

[0035] Reaction sputtering has inherent "hysteresis effect", which is significantly amplified by long loop, and the system stays in "transition zone" (near the target voltage interval) for a long time. Hysteresis effect refers to the change relationship between reaction gas flow and oxygen partial pressure in the reaction chamber, that is, the composition of vanadium oxide obtained is not the same even if the reaction gas partial pressure in the reaction chamber is the same, but the reaction gas flow is in different states of increase / decrease. Reducing the oxygen flow, the sputtering rate will not immediately return from low to high, but will show a slow rising state, and small changes in oxygen have a great effect on oxidation degree.

[0036] Voltage and valence state of vanadium oxide:

[0037] In summary, the gas delivery path is too long, the response is lagging; and the gas control unit has inherent hysteresis effect, the superposition of lag and hysteresis leads to continuous over / under control of oxygen flow, and the long loop amplifies the inherent regulation time of the gas control unit, so that the target oxygen partial pressure fluctuates in a large range when adjusting, resulting in low stability of the target voltage.

[0038] To solve the above problems, the present application cancels the long gas nozzle structure in the existing reaction chamber, integrates the reaction gas delivery channel inside the heater, so that the oxygen gas is directly supplied into the chamber from below the wafer, thereby shortening the gas control loop path and the response time required by the control system. Shorten the time of reaction gas staying in the transition zone, and finally achieve the purpose of improving the stable control of the target voltage.

[0039] However, if the reaction gas is directly supplied from the gas hole below the wafer, it will cause high oxygen concentration at the edge of the wafer, generating high-valence VOx, and the Rs of the edge area is large; the middle is hypoxic and generates low-valence VOx, the middle Rs is small, and the Rs distribution is uneven.

[0040] To solve this problem, the gas inlet holes below the wafer are designed into a differentiated layout pattern: the number of gas inlet holes around the wafer is greater than that in the middle. At this time, the wafer edge region has more ventilation, the convection is stronger, the edge region temperature rises higher than the center region, the high temperature makes the oxygen precipitation amount of the edge region film higher than that of the middle region, and the edge region Rs is significantly reduced, thereby solving the problem of uneven distribution of wafer Rs.

[0041] The non-uniform gas inlet hole compensates for the inherent deposition unevenness of the wafer edge and center, thereby improving the uniformity of the film as a whole; the oxygen partial pressure adjustment rate is improved by shortening the gas delivery path, the target voltage fluctuation range is narrowed, and finally the steady state control is realized.

[0042] After introducing the basic principles of the present application, the various non-limiting embodiments of the present application will be specifically introduced below. Any element quantity in the drawings is used for example and not limitation, and any naming is only used for differentiation and does not have any limiting meaning.

[0043] The principles and spirits of the present application will be explained in detail below with reference to several representative embodiments of the present application.

[0044] Example 1: As Figure 1 shown in the drawings, a VOx film steady-state growth gas inlet device based on fast response gas control is used to inject reaction gas into a reaction chamber 1 in a VOx film sputtering system, the reaction chamber 1 is provided with a susceptor 2 and a heater arranged inside the susceptor 2, the gas inlet device comprises a reaction gas delivery channel 3, a plurality of gas inlet holes 21 and a control unit; the plurality of gas inlet holes 21 are arranged on the table surface of the susceptor 2; one end of the reaction gas delivery channel 3 is connected with an external reaction gas source, the other end is arranged below the susceptor 2 and communicates with the gas inlet holes 21, the reaction gas delivery channel 3 delivers reaction gas for the reaction chamber 1; an electric valve is arranged on the reaction gas delivery channel 3, and the control unit adjusts the reaction gas flow into the reaction chamber 1 by controlling the electric valve.

[0045] Part of the pipeline of the reaction gas delivery channel 3 (hereinafter referred to as delivery channel 3) is integrated in the heater, and the heater heats the reaction gas in the delivery channel 3. The pipeline integrated in the heater is a heating channel, and the delivery channel 3 is provided with a pneumatic valve (this is a second pneumatic valve) upstream of the heating channel in the gas flow direction. The delivery channel 3 is also provided with another pneumatic valve (this is a first pneumatic valve) at the end close to the external gas source, and then a pressure regulating valve and a flow meter are arranged in sequence along the gas flow direction. The above two pneumatic valves are fast response valves, preferably piezoelectric valves or voice coil valves. The delivery channel 3 is used to deliver reaction gas, i.e. oxygen, of course, in other embodiments, it can also be used to deliver inert gas, i.e. argon.

[0046] The control unit controls the pneumatic valve, pressure regulating valve and flow meter arranged on the conveying channel 3 according to the target surface voltage fluctuation to adjust the flow of the reaction gas into the internal conveying channel 3 of the heater, and further control the flow of the gas into the reaction cavity 1. In the embodiment, the control unit is a programmable logic controller.

[0047] As shown in Figure 2 , the distribution of the plurality of gas inlet holes 21 on the base 2 table surface is that the density of the edge area below the wafer is greater than that of the center area, so as to improve the temperature of the edge area of the wafer, and further compensate the sheet resistance value of the center area of the wafer. In the embodiment, the gas inlet hole 21 is arranged as a blind hole, and the gas inlet hole 21 is distributed in the form of multiple concentric circular rings on the base 2 table surface, and the distribution density of the gas inlet hole 21 increases from the inner ring to the outer ring. As a preferred scheme of the embodiment, three concentric circular rings of gas inlet holes 21 are arranged on the base 2 table surface, the gas inlet holes 21 have the same diameter, but the number of the outer ring gas inlet holes 21 is 1.5 times that of the center area.

[0048] Of course, in other embodiments, the number of concentric circles arranged on the base 2 can be 2, 4, 5 or more, and the number of concentric circles can be set according to actual needs. From the inner ring to the outer ring, the distribution of the gas inlet hole 21 can also be that the distribution density of the gas inlet hole 21 remains unchanged, and the diameter increases; or the distribution density of the gas inlet hole 21 increases while the diameter increases. The number of gas inlet holes 21 per unit area on the edge area of the base 2 table surface is any value in the range of 1.5-3 times that of the center area, such as 2 times, 2.5 times, 3 times, etc.

[0049] In the embodiment, the gas inlet hole 21 arranged in the form of a blind hole has a bottom connected to the conveying channel 3 through a transverse communication hole 22, and each gas inlet hole 21 corresponds to a transverse communication hole 22. The gas inlet holes 21 located in different concentric circles have different depths; the base 2 is internally provided with three layers of transverse communication holes 22, the number of layers of the transverse communication holes 22 is the same as the number of rings of the concentric circles of the gas inlet holes 21, and each layer of transverse communication holes 22 is connected to the bottom of the corresponding ring of gas inlet holes 21 located at the same depth; each layer of transverse communication holes 22 is arranged in a radial manner (as Figure 3The gas inlet holes 21 of different depths are connected by the transverse communication holes 22 of different levels, forming independent gas delivery branches isolated from each other in different annular regions, which ensures that the gas flow to a specific region of the wafer will not be affected by the gas regulation to other regions. Moreover, the flow channels (i.e. the transverse communication holes 22) are dispersed at different depths, avoiding excessive cutting in a single plane, which is conducive to maintaining the overall structural rigidity of the susceptor 2. At the same time, this arrangement is also conducive to the layout of the heater thermal field. Compared to concentrating all flow channels in one layer, which causes serious interference to the local thermal field, the layered arrangement of flow channels can reduce the adverse effects on the uniformity of the heater temperature, thereby indirectly ensuring the uniformity of the substrate heating, and thus improving the deposition quality of the thin film.

[0050] The above gas inlet device is suitable for a magnetron sputtering system for vanadium oxide thin film.

[0051] Comparison Figure 4 and Figure 5 It can be concluded that the direct gas path shortens the feedback delay. The present application cancels the traditional gas nozzle and integrates the oxygen delivery channel inside the heater, so that the oxygen gas directly passes through the reaction zone from the back of the wafer. The oxygen control node is shortened, the response time of the control unit is reduced, and the residence time in the transition zone is shortened.

[0052] In order to improve the uniformity of oxygen distribution in the working space of the chamber, the traditional sputtering system generally provides a long gas nozzle on the side wall of the reaction chamber, so that the delivery channel needs to be extended to the middle of the reaction chamber, and then communicated with the adapter installed outside the reaction chamber. The reaction gas flows into the long gas nozzle through the adapter, and then reaches the reaction chamber. The traditional gas inlet device has the problem of long gas delivery path, which further prolongs the gas control loop and aggravates the response lag problem of gas control. As shown in the traditional gas control loop diagram Figure 4 During the reaction sputtering process, oxygen is output from the oxygen cylinder, passes through the first pneumatic valve, pressure regulating valve, flow meter, second pneumatic valve and other execution elements in turn, and then enters the vacuum chamber through the pipeline, adapter and gas nozzle; at the same time, the target surface voltage (reflecting the reaction state such as “target poisoning”) is fed back to the programmable logic controller (i.e. the control unit), which in turn controls the first pneumatic valve and other execution elements, forming a gas closed-loop control loop based on the feedback of the target surface voltage, to realize the regulation of the reaction gas (oxygen) flow and maintain the reaction process.

[0053] The application cancels the long gas nozzle structure in the reaction cavity, sets the gas inlet hole on the base table, sets the heater in the base, and supplies the gas to the gas inlet hole on the base table through the heater. The gas inlet hole is set on the base table, which greatly shortens the gas delivery path. The gas delivery path directly enters the reaction cavity from the bottom of the reaction cavity without passing through the middle of the reaction cavity and the long gas nozzle. By shortening the gas delivery path, the gas control loop is shortened. As shown in the gas control loop diagram of the application, Figure 5 After the oxygen is heated by the heater in the base, the oxygen enters the vacuum cavity through the gas inlet hole and participates in the reaction sputtering process of the target material. At the same time, the target surface voltage (reflecting the reaction state of "target poisoning") is fed back to the programmable logic controller (i.e. the control unit), and the control unit controls the first pneumatic valve and other execution elements in real time to form a gas closed-loop control loop based on the feedback of the target surface voltage, so as to realize the closed-loop control of the oxygen flow and ensure the stability of the reaction sputtering process.

[0054] The gas inlet device of the application optimizes the gas delivery path, shortens the gas delivery path, shortens the response time of the gas control loop, and shortens the residence time of the reaction gas in the transition zone (near the target voltage interval), thereby improving the stable control of the target surface voltage.

[0055] Figure 6 And 7 The schematic diagram of the process of the target surface voltage from the initial dynamic change to the final stability with the development of the "target poisoning" effect during the reaction sputtering before and after the improvement.

[0056] Comparison Figure 6 And 7 It can be seen that after the improvement, the target voltage fluctuation is narrowed, the oxygen partial pressure regulation rate is improved, and the time is shortened from 86.346s to 56.346s before the improvement; and the oxygen partial pressure steady state control is realized.

[0057] Figure 8 The distribution map of the wafer surface resistance value before the improvement, from which it can be seen that the average resistance value before the improvement is 426.72KΩ, and the uniformity is 4.521%. Figure 9 The distribution map of the wafer surface resistance value of the application, from which it can be seen that the average resistance value after the improvement is 307.72KΩ, and the uniformity is 0.82%.

[0058] Comparison Figure 8 And Figure 9 It can be seen that the wafer surface resistance value uniformity of the application is better than that before the improvement.

[0059] Example 2: The main difference between this example and Example 1 is that: In this example, the reaction gas delivery channel includes a first branch and a second branch which are independent of each other, the first branch supplies gas to the gas inlet holes in the central region, and the second branch supplies gas to the gas inlet holes in the peripheral edge region, and the first branch and the second branch are respectively provided with valve members which can independently adjust the flow rate.

[0060] According to the above description of the present specification, those skilled in the art can also understand that the terms used such as "upper", "lower", "inner", "outer", "depth" and the like indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings of the present specification, which are only for the purpose of facilitating the description of the present application and simplifying the description, and are not explicitly or implicitly indicating or suggesting that the devices or elements involved must have the specific orientation, be constructed and operated in a specific orientation, therefore the above orientation or positional relationship terms cannot be understood or interpreted as a limitation on the present application.

[0061] In addition, in the description of the present specification, the meaning of "a plurality of" is at least two, such as two, three or more, etc., unless otherwise explicitly and specifically limited.

Claims

1. A steady-state growth inlet device based on fast response gas control for VOx thin film, for injecting reaction gas into a reaction chamber in a VOx thin film sputtering system, wherein a pedestal and a heater arranged inside the pedestal are arranged inside the reaction chamber, characterized in that: The gas inlet device comprises: ​ a reaction gas delivery channel connected with an external reaction gas source to deliver reaction gas to the reaction cavity, the delivery channel being arranged below the susceptor; a plurality of gas inlets arranged on the susceptor table and in communication with the delivery channel, the distribution of the gas inlets on the susceptor table being such that the density of the gas inlets in the edge region below the wafer is greater than that in the central region.

2. The rapid response gas control based VOx thin film steady state growth in-gas apparatus of claim 1, wherein, The gas inlets are blind holes, the bottoms of which are in communication with the delivery channel through transverse communication holes.

3. The rapid response gas control based VOx thin film steady state growth in-gas apparatus of claim 2, wherein, The gas inlets are distributed in the form of multiple concentric circular rings, and from the inner ring to the outer ring, the distribution density of the gas inlets increases and / or the hole diameter increases.

4. The rapid response gas control based VOx thin film steady state growth in-gas apparatus of claim 3, wherein, The gas inlets in different concentric circular ring regions have different depths.

5. The rapid response gas control based VOx thin film steady state growth in-gas apparatus as claimed in claim 2, wherein, The number of gas inlets per unit area in the edge region of the susceptor table is 1.5-3 times that in the central region.

6. The rapid response gas control based VOx thin film steady state growth in-gas apparatus as claimed in claim 2, wherein, At least a part of the delivery channel is integrated in the heater, and the delivery channel integrated in the heater is a heating channel.

7. The rapid response gas control based VOx thin film steady state growth in-gas apparatus as claimed in claim 6, wherein, The delivery channel is provided with a pneumatic valve upstream of the heating channel in the direction of gas flow.

8. The rapid response gas control based VOx thin film steady state growth in-gas apparatus as claimed in claim 7, wherein, A control unit is further included, which controls the pneumatic valve upstream of the heater to adjust the flow of reaction gas into the delivery channel in the heater according to the fluctuation of the target surface voltage.

9. The rapid response gas control based VOx thin film steady state growth in-gas apparatus as claimed in claim 2, wherein, The reaction gas delivery channel comprises a first branch and a second branch which are independent of each other, the first branch supplies gas to the gas inlets in the central region, the second branch supplies gas to the gas inlets in the edge region, and the first branch and the second branch are respectively provided with valve members capable of independently adjusting the flow.

10. The fast response gas controlled VOx thin film steady state growth inlet device according to any one of claims 1-9, wherein, The gas inlet device is suitable for a magnetron sputtering system for vanadium oxide thin films.

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