Method for depositing aluminum nitride film on patterned substrate

Abstract

The embodiment of the invention provides a method for depositing an aluminum nitride film on a patterned substrate, which comprises the following steps of: performing sputtering deposition treatment by adopting a physical vapor deposition process to deposit and form the aluminum nitride film on the patterned substrate; wherein the sputtered target material is an aluminum target material, and the patterned substrate is a sapphire substrate; and keeping the patterned substrate in a grounding state in the process of performing the sputtering deposition treatment. By adopting the scheme of the embodiment of the invention, in the sputtering deposition process of the aluminum nitride film, the patterned substrate is in the grounding state, charges accumulated on the surface in the deposition process are neutralized, and the same grounding potential is integrally formed on the surface of the substrate; therefore, the problem that the motion trail, the collision behavior, the adsorption characteristic and the deposition process of the aluminum atoms are affected by a non-uniform electric field formed on the surface of the substrate is avoided, the re-reflection stage number in the sputtering process is increased, the overall coverage uniformity of the surface is improved, and the step coverage rate is increased.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor process technology, and in particular to a method for depositing an aluminum nitride film on a patterned substrate. Background Art

[0002] In order to improve the light output efficiency and luminous efficiency of LEDs, the prior art has proposed a technical solution of patterned sapphire substrates. Before depositing an epitaxial layer on the surface of the patterned sapphire substrate, an aluminum nitride buffer layer still needs to be deposited on the surface to suppress the stress of the subsequent epitaxial layer and reduce the defects of the epitaxial layer.

[0003] Due to the local structural limitations of the patterned substrate and the limitations of the aluminum nitride film deposition process, the aluminum nitride film deposition has the problems of poor step coverage, the formation of overhangs on the patterned substrate, and the inability to deposit film in some areas. Figure 1 Figure 1 is a schematic cross-sectional view of two types of patterned substrates after aluminum nitride films are deposited. Figure 1 As shown in the figure, for the groove-type structure, an overhang is formed at the corner area of ​​the top of the groove, and no film is deposited at the corner of the bottom of the groove, exposing the substrate; for the convex-type pattern, an overhang is formed at the root of the convex without depositing a film. The problem of being unable to deposit a film at the corner will cause seed crystal generation during the GaN epitaxial growth process and cause serious dislocation.

[0004] In order to improve the step coverage, the related art proposes to use collimator vapor deposition equipment, long cavity distance vapor deposition equipment and ionized metal plasma vapor deposition equipment, and use the above equipment to achieve process control and improve the problem of poor step coverage. However, the equipment using the above process either abandons the effective deposition yield of sputtered atoms, or greatly increases the atomic free path of sputtered atoms, and even bombards the deposited film layer with ions, which makes it impossible to guarantee the uniformity of the film quality. Summary of the invention

[0005] The embodiment of the present disclosure provides a method for depositing an aluminum nitride film on a patterned substrate, and adopts conventional physical vapor deposition equipment to form a better aluminum nitride film on the patterned substrate.

[0006] In a first aspect, an embodiment of the present disclosure provides a method for depositing an aluminum nitride film on a patterned substrate, comprising:

[0007] A magnetron sputtering vapor deposition process is used to perform sputtering deposition processing to deposit an aluminum nitride film on a patterned substrate;

[0008] Wherein: the sputtered target material is an aluminum target material, and the patterned substrate is a sapphire substrate; and the patterned substrate is kept in a grounded state during the sputtering deposition process.

[0009] Optionally, during the sputtering deposition process, the flow rate ratio of nitrogen gas to argon gas is controlled to be between 3.3 and 6.0, and the specific nitrogen flow rate is determined according to the aspect ratio of the substrate pattern in the patterned substrate;

[0010] Wherein: the specific nitrogen flow rate is used to make the step coverage of the patterned substrate reach at least a target step coverage rate, and the specific nitrogen flow rate is in a preset positive correlation with the aspect ratio of the substrate pattern.

[0011] Optionally, the relationship between the specific nitrogen flow rate and the aspect ratio of the substrate pattern is: Where p is the step coverage, k is the proportionality coefficient, is the specific nitrogen flow rate, and AR is the step coverage rate.

[0012] Optionally, the aluminum target material is a target material having a periodic micro-bevel structure on the sputtered surface; the micro-bevel structure is used to allow aluminum atoms sputtered from the surface of the aluminum target material to enter the substrate pattern in a direction that is not perpendicular to the surface of the patterned substrate;

[0013] The inclination angle of the micro-bevel structure is determined according to the aspect ratio of the patterned substrate, and the periodic size of the micro-bevel structure is determined according to the size of the substrate pattern and the target base spacing between the aluminum target and the patterned substrate surface.

[0014] Optionally, the micro-bevel structure is a symmetrical triangular prism-shaped microstructure or a pyramid-shaped microstructure;

[0015] The angle between the side of the micro-bevel structure and the surface of the patterned substrate is less than arctan(D / W), and the repetition period of the micro-bevel structure is less than 2(L+D)tan(D / W)-W, where D is the depth of the substrate pattern, W is the width of the substrate pattern, and L is the target-base spacing.

[0016] Optionally, before performing the sputtering deposition process on the aluminum target, the method further includes:

[0017] The patterned substrate is subjected to high-temperature oxidation treatment under vacuum conditions to form a surface aluminum oxide layer on the surface of the patterned substrate; the surface aluminum oxide layer has a structure different from that of the single-crystal aluminum oxide of the substrate.

[0018] Optionally, during the sputtering deposition process, the temperature of the patterned substrate is controlled between 800-900°C.

[0019] Optionally, during the sputtering deposition process, a heating function of a chamber heater of the sputtering device is turned on, and the chamber heater is used to heat the aluminum target material to increase the initial energy of aluminum atoms formed by sputtering.

[0020] The chamber heater heats the aluminum target and sputters the aluminum target so that an average kinetic energy of aluminum atoms formed by sputtering is higher than 1000 eV.

[0021] Optionally, during the sputtering deposition process, the pressure of the sputtering equipment chamber is controlled to be (1-5)×10 -4 Torr or less, and control the target base distance from the aluminum target to the substrate to be 3-6 cm.

[0022] By adopting the embodiment scheme of the present disclosure, during the sputtering deposition of aluminum nitride film, the patterned substrate is placed in a grounded state, so that the charges accumulated on the surface during the deposition process are neutralized, and the entire surface of the substrate forms the same ground potential, thereby avoiding the problem that the uneven electric field formed on the substrate surface affects the movement trajectory, collision behavior, adsorption characteristics and deposition process of aluminum atoms, thereby increasing the re-reflection level during the sputtering process, improving the overall surface coverage uniformity, and thereby improving the step coverage rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art description. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work, including:

[0025] Figure 1 are schematic cross-sectional views of two types of patterned substrates after aluminum nitride films are deposited;

[0026] Figure 2 This is a schematic diagram of ideal film formation using a planar target for magnetron sputtering in the prior art;

[0027] Figure 3 is a schematic diagram of magnetron sputtering using a microstructured target in some embodiments of the present disclosure;

[0028] Figure 4 is a schematic diagram of sputtering an aluminum nitride film on a patterned substrate using an aluminum target with a micro-section structure in some embodiments;

[0029] Figure 5 is a microscopic schematic diagram of forming an aluminum nitride film on a patterned substrate using the aforementioned process;

[0030] Figure 6 It is a microscopic schematic diagram of the existing process for forming an aluminum nitride film on the same patterned substrate. DETAILED DESCRIPTION

[0031] Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be construed as being limited to the embodiments described herein, which are instead provided for a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are only for exemplary purposes and are not intended to limit the scope of protection of the present disclosure.

[0032] The term "including" and its variations used in this document are open inclusions, that is, "including but not limited to". The term "based on" means "based at least in part on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments". Relevant definitions of other terms will be given in the description below. It should be noted that the concepts of "first", "second", etc. mentioned in this disclosure are only used to distinguish different devices, modules or units, and are not used to limit the order or interdependence of the functions performed by these devices, modules or units.

[0033] In order to solve the problem that the existing use of specific equipment to implement a specific process to improve the step coverage of aluminum nitride film brings various negative effects, the embodiment of the present disclosure provides a new method for depositing aluminum nitride film on a patterned substrate. The method provided by the embodiment of the present disclosure can be implemented using conventional magnetron sputtering vapor deposition equipment.

[0034] In the embodiment of the present disclosure, during the process of sputtering deposition treatment of the patterned substrate by the magnetron sputtering vapor deposition process, and then depositing the aluminum nitride film on the patterned substrate, the patterned substrate is kept in a grounded state. The patterned substrate in the embodiment of the present disclosure is a sapphire substrate, the sputtering target material in the sputtering deposition process is an aluminum target material, and the physical vapor deposition process introduces argon gas for sputtering and nitrogen gas for combining with aluminum atoms to form a deposit into the chamber of the vapor deposition equipment.

[0035] During the magnetron sputtering deposition process, the surface of the patterned substrate gradually accumulates charges in the process of receiving aluminum atoms. The charges gradually accumulate on the surface of the patterned substrate (and mainly accumulate in the sharp corners of the surface of the patterned substrate), so that a high-intensity electric field is formed on the surface of the patterned substrate. The aforementioned electric field affects the motion trajectory of the sputtered aluminum atoms, which may cause the aluminum atoms to be repelled from certain areas of the substrate and reduce the re-reflection order. Specifically, when too much positive charge accumulates on the surface of the patterned substrate, a local potential difference will be generated on the surface of the patterned substrate. The electric field formed by the local potential difference causes the electric field of the patterned substrate to be non-uniformly distributed, changing the deposition path and kinetic energy distribution of the deposited aluminum atoms, causing the aluminum atoms to be reflected in different ways on the surface of the patterned substrate, affecting its re-reflection order, and then causing the thickness of the aluminum nitride film of the substrate in different areas to be different, resulting in the problem of poor step coverage.

[0036] Here is an explanation of the re-reflection order. The re-reflection order is the number of times the sputtered atoms are reflected again. During the sputtering deposition process, the atoms sputtered onto the substrate are sputtered and deposited again, forming a series of reflection and deposition processes, which can be characterized by the re-reflection order. The increase in the re-reflection order can effectively improve the uniformity and coverage of sputtering deposition, which is specifically characterized by the sputtered atoms being able to be more widely distributed on the target surface and covering more surface area. Because the sputtered atoms are more widely distributed on the target surface, the uncovered area is reduced, which improves the uniformity of the deposited layer.

[0037] During the sputtering deposition process, the substrate is grounded to neutralize the charge accumulated on the surface during the deposition process, and the entire surface of the substrate forms the same ground potential, thereby avoiding the problem of the uneven electric field formed on the substrate surface affecting the movement trajectory, collision behavior, adsorption characteristics and deposition process of aluminum atoms, increasing the re-reflection level during the sputtering process, improving the overall surface coverage uniformity, and thus improving the step coverage rate.

[0038] In a specific implementation, in addition to keeping the patterned substrate in a grounded state, the following process steps may be used to further improve the uniformity of the aluminum nitride film formed on the surface of the patterned substrate.

[0039] In some embodiments, during the sputtering deposition process, the flow ratio of nitrogen to argon is controlled to be between 3.3-6.0. In a specific implementation, in order to ensure the uniformity of aluminum nitride film deposition, it is necessary to control a lower sputtering rate (the goal is to ensure uniform diffusion of the deposition, thereby improving the uniformity of the deposited film), so it is necessary to reduce the amount of argon used. In the application of a specific device, the argon flow rate is controlled between 1-15sccm by controlling the gas intake setting of the physical vapor deposition equipment. According to the aforementioned nitrogen and argon power ratio, the nitrogen power can be controlled between 50-90sccm.

[0040] In addition, in the embodiment of the present disclosure, in addition to realizing the flow control of nitrogen according to the aforementioned flow ratio of nitrogen and argon, the specific nitrogen flow rate used is also determined according to the aspect ratio of the substrate pattern in the patterned substrate. Specifically, the controlled flow rate of nitrogen is in a preset positive correlation with the aspect ratio of the substrate, and the specific nitrogen flow rate is used to make the step coverage of the aluminum nitride film deposited on the surface of the substrate reach at least the target step coverage. Here, the step coverage refers to the ratio of the thickness of the deposited film layer at the step to the thickness of the film layer at the flat part.

[0041] In the specific implementation, through a large number of experimental findings, by using a higher nitrogen intake, more aluminum nitride deposits can be delivered to the pattern grooves (or pattern void areas) of the patterned substrate, forming better aluminum nitride deposition in the pattern grooves. In addition, a higher nitrogen flux can improve the distribution of the deposits, making the deposition of the deposits on the side of the substrate pattern (that is, the step surface) more uniform, thereby reducing the problem of poor substrate patterns. And through a large amount of experimental data, it was found that within a reasonable nitrogen flux range, increasing the nitrogen flux according to the aspect ratio of the substrate pattern can achieve better step coverage. Based on this, in the embodiment of the present disclosure, the nitrogen ventilation rate is set to be in a preset positive correlation with the aspect ratio of the substrate pattern.

[0042] In some embodiments, when other process parameters remain constant, it is experimentally determined that the step coverage of the substrate pattern, the nitrogen ventilation volume, and the aspect ratio of the substrate pattern have a certain relationship. , where p is the step coverage, k is the proportionality coefficient, is the specific nitrogen flow rate, and AR is the step coverage. Therefore, the positive correlation between the aspect ratio of the pattern and the nitrogen ventilation volume can be determined in advance, and the nitrogen flow rate can be adjusted according to the positive correlation and the aspect ratio of the substrate pattern.

[0043] After aluminum atoms are sputtered from the aluminum target, their initial positions on the patterned substrate surface after the transport process are random. Subsequently, the sputtered aluminum atoms are adsorbed on the substrate surface to form augmented atoms and undergo transient migration on the substrate surface. During the transient migration on the substrate surface, the augmented atoms will also exchange energy with the substrate atoms to reduce their energy below the resolution energy, thereby achieving deposition. The augmented atoms that have not been reduced to below the resolution energy continue to migrate transiently. The proportion of augmented atoms migrating on the substrate surface can be characterized by the diffusion coefficient. Where D0 is the initial proportional coefficient, E d is the analytical energy, K B is the Boltzmann constant, and T is the substrate temperature.

[0044] According to the formula in the previous paragraph, in addition to the energy of the sputtered aluminum atoms themselves, the activation energy of the substrate surface and the substrate temperature both affect the migration of the sputtered aluminum atoms on the substrate surface. The sufficient migration of the sputtered aluminum atoms on the substrate surface is conducive to the uniform film formation of aluminum nitride. Therefore, the embodiment of the present disclosure considers increasing the diffusion (transient migration) of the aluminum atoms in the substrate by reducing the activation energy of the substrate surface and increasing the substrate temperature, thereby improving the step coverage.

[0045] According to the above ideas, in some embodiments of the present disclosure, the step coverage is improved by reducing the activation energy of the substrate surface. Specifically, in some embodiments of the present disclosure, before performing the above sputtering process on the aluminum target, the computing device may also perform the following S110.

[0046] S110: performing a high-temperature oxidation treatment on the patterned substrate under vacuum conditions to form a surface oxide layer on the surface of the patterned substrate.

[0047] In a specific implementation, a vacuum heat treatment furnace can be used to perform high temperature oxidation treatment on the patterned substrate. -3 -5×10 -3 The temperature of the patterned substrate is controlled between 700-800° C. under a 0.1 Torr vacuum process pressure, and 30 sccm of high-purity oxygen is introduced to perform a high-temperature oxidation treatment on the patterned substrate for 300 seconds, so that a surface oxide layer is formed on the surface of the patterned substrate.

[0048] By adopting the above-mentioned process to carry out high temperature oxidation treatment, a surface oxide layer is formed on the surface of the patterned substrate, which can reduce the surface energy of the patterned substrate surface, thereby making it easier for aluminum atoms to diffuse on the surface of the patterned substrate. The surface oxide layer is an oxide layer different from the original single crystal aluminum oxide structure of the substrate. In addition, the high temperature oxide layer formed above has a dense characteristic, which can also serve as a protective layer to prevent aluminum atoms from directly contacting nitrogen atoms in the atmosphere, thereby reducing the early nucleation of aluminum nitride film on the patterned substrate, reducing the combination of aluminum atoms in diffusion migration, and making the aluminum nitride film more uniform. In addition, the surface oxide layer obtained by the above-mentioned oxidation treatment has a lower interface energy, which can increase the re-reflection order during the deposition process of aluminum atoms, thereby improving its diffusion capacity.

[0049] The applicant here calls attention to the fact that the existing pre-treatment of sapphire substrates (excluding graphic treatment) is to use nitrogen, ammonia and other nitrogen-containing gases to nitride or ammoniate the substrate, so that ammonia bonds or nitrogen bonds are suspended on the bottom surface, thereby providing more nucleation points for the growth of aluminum nitride, accelerating the nucleation of aluminum nitride and subsequent film formation. However, the processing steps of the sapphire substrate in this scheme are opposite to those of the prior art. The high-temperature oxidation treatment of the sapphire substrate is not to accelerate nucleation, but to reduce its nucleation rate, thereby increasing the diffusion capacity of aluminum atoms (increase atoms) in the substrate to optimize subsequent film formation.

[0050] As analyzed above, by increasing the temperature of the patterned substrate surface, the diffusion of aluminum atoms (increased atoms) on the substrate surface can be increased. Specifically, during the sputtering deposition process, the substrate can be heated to control the temperature of the patterned substrate between 800-900°C, thereby reducing the energy consumption caused by the energy difference between the aluminum atoms formed by sputtering and the substrate, thereby increasing the diffusion capacity of aluminum atoms on the substrate surface.

[0051] According to the principles of thermodynamics, in addition to improving the diffusion ability of aluminum atoms on the surface of the patterned substrate by the aforementioned method, the diffusion ability of aluminum atoms on the surface of the patterned substrate can also be improved by increasing the energy of the sputtered aluminum atoms. In a specific implementation, the energy of the sputtered ions (the energy of the argon ions) can be increased by increasing the sputtering control power, thereby increasing the energy of the aluminum atoms formed by sputtering. However, the sputtering control power needs to be significantly increased in the aforementioned manner. In actual applications, increasing the sputtering power is limited by the power, heat dissipation and safety control of the equipment itself.

[0052] To solve the aforementioned problem, in some embodiments of the present disclosure, during the sputtering deposition process, the heating function of the chamber heater of the sputtering equipment is turned on, and the chamber heater is used to heat the aluminum target to increase the initial energy of the aluminum atoms formed by sputtering. The function of the chamber heater of the existing sputtering equipment is to heat the chamber before the equipment is started, to volatilize the moisture and other volatile substances in the chamber and remove impurities in the chamber, and to heat the substrate. It is not used to heat the target. In the embodiments of the present disclosure, the heating function of the chamber heater is reused to heat the aluminum target, reduce the binding energy of the surface aluminum atoms, and increase the initial energy of the aluminum target atoms, so that the bombardment points formed by the energetic ions bombarding the surface of the aluminum target quickly heat up to form high-energy aluminum atoms. In a specific implementation, by turning on the chamber heater, the temperature of the aluminum target can be controlled to be greater than 600°C.

[0053] In a specific implementation, in addition to using the aforementioned heating function of turning on the chamber heater, the sputtering control power can also be appropriately increased to increase the initial energy of the aluminum atoms formed by sputtering by increasing the sputtering ion energy. For example, in some embodiments, the sputtering power can be controlled to be at least greater than 6Kw. Through the aforementioned heating treatment and the treatment of increasing the sputtering power, the energy of the sputtered aluminum atoms can be made at least greater than 1000eV, thereby significantly improving the initial energy of the sputtered aluminum atoms.

[0054] It should be noted here that, as analyzed in the previous article, in order to ensure the quality of film formation, it is necessary to control the sputtering rate at a lower level, and accordingly, a smaller argon flow rate needs to be used (as analyzed in the previous article, during the sputtering process, the nitrogen flow rate is controlled at 1-15sccm). In practical applications, the sputtering rate is related to the argon ion concentration in the chamber of the sputtering equipment. The smaller the argon ventilation flow rate, the lower the concentration of the corresponding sputtered aluminum atoms, which can be fully diffused in the chamber and on the substrate surface, reducing the redeposition and aggregation of the material, thereby avoiding uneven accumulation of deposited materials in the step area of ​​the patterned substrate. In simple terms, by adopting a smaller argon flow rate, uniform coverage of the aluminum nitride film on the uneven substrate surface can be achieved through slow deposition, thereby improving the step coverage rate.

[0055] In practical applications, in order to achieve a better step coverage, in addition to increasing the energy of the aluminum atoms formed by the sputtering, the energy loss of the aluminum atoms formed by the sputtering during the operation process should be as small as possible. Before reaching the substrate surface, the aluminum atoms formed by the sputtering randomly collide with the gas atoms and other aluminum atoms in the chamber, changing the direction of movement and losing some energy. The number of random collisions experienced by the sputtered aluminum atoms during transportation is The corresponding mean free path is: where P is the sputtering gas pressure, d is the target-base distance, δ is the collision cross section of the sputtered aluminum atoms, and K B is the Boltzmann constant, T g is the sputtering gas temperature. When the initial energy of the sputtered aluminum atoms and the sputtering gas temperature are constant, the sputtering gas pressure P and the target-base distance d directly affect the number of random collisions experienced by the sputtered aluminum atoms. Based on this, the sputtering gas pressure P and the target-base distance d should be reduced as much as possible.

[0056] In a specific application of the embodiment of the present disclosure, the gate valve opening of the cold pump and the sputtering equipment process chamber is set to 100%, and the nitrogen and argon gas flow rates are reasonable, so that the pressure of the sputtering chamber is (1-5)×10 -4In addition, in the disclosed embodiment, considering that a smaller target-base distance will cause argon plasma to etch the surface of the sapphire substrate (affecting the growth of aluminum nitride film), a larger target-base distance will increase the number of random collisions of sputtered aluminum atoms, and combined with the structural size characteristics of the sputtering equipment in practical applications, the target-base distance is set to 3-6 cm, preferably 3-4 cm.

[0057] Figure 2 This is an ideal film formation schematic diagram using a planar target for magnetron sputtering in the prior art. Figure 2 As shown in the figure, in theory, aluminum atoms sputtered from the surface of the aluminum target move toward the substrate in a direction perpendicular to the aluminum target. If the movement trajectory remains unchanged, the aluminum atoms are deposited on the substrate surface in a manner perpendicular to the entire surface of the substrate, and cannot form a film on the step surface (that is, the side) of the groove graphic area. Specifically, it is the direction of the aluminum target surface that limits the film formation of aluminum nitride on the substrate surface.

[0058] Figure 3 Schematic diagram of magnetron sputtering using a microstructured target in some embodiments of the present disclosure. Figure 3 As shown, in order to allow aluminum atoms to enter the substrate pattern as much as possible and be evenly distributed on the side surface of the patterned substrate, this scheme allows the aluminum atoms to be sputtered at a certain angle relative to the surface of the patterned substrate, and the angle between the sputtering angle and the surface of the patterned substrate should not be too large or too small.

[0059] In order to adjust the sputtering angle and make the patterned substrate side of the patterned substrate have similar deposition rate and film quality as much as possible, the aluminum target material used in the embodiment of the present disclosure is a target material with a special surface structure setting. Specifically, the aluminum target material is a target material with a periodic micro-bevel structure on the sputtered surface, that is, the micro-bevel structure is repeated on the surface of the aluminum target material in a periodic manner. The aforementioned micro-bevel structure is used to allow the aluminum atoms sputtered from the surface of the aluminum supermaterial to enter the substrate pattern in a manner that is non-perpendicular to the surface of the patterned substrate. The inclination angle of the micro-bevel structure is determined according to the aspect ratio of the patterned substrate, and its periodic size is determined according to the size of the substrate pattern (that is, the aspect ratio) and the target-base distance between the aluminum target material and the patterned substrate surface.

[0060] like Figure 3 As shown, in some embodiments, in order to allow the two side walls (or even more side walls) in the groove of the patterned substrate to be relatively evenly deposited with aluminum nitride film (that is, directly deposited by aluminum atoms), the aforementioned micro-bevel structure interface is triangular, and the corresponding micro-bevel structure can be a micro-triangular prism-type microstructure or a pyramid-type microstructure.

[0061] The triangular prism type microstructure refers to a periodically repeated microstructure like a triangular prism arranged on the surface of the aluminum target and arranged in parallel and repeatedly, and the two sides of the triangular prism form two adjacent inclined surfaces of a repetitive microstructure, and each triangular prism type microstructure is arranged in sequence. Preferably, the adjacent inclined surfaces are microstructures with the same inclination angle and the same length.

[0062] The pyramidal microstructure refers to a periodically repeated microstructure, such as a pyramid arranged on the upper surface of the aluminum target and periodically repeated in both directions. The four sides of the pyramid form a repetitive microstructure. Preferably, the aforementioned pyramidal microstructure has the same angle between the four faces and the bottom surface.

[0063] Figure 4 Schematic diagram of some embodiments using an aluminum target with a micro-section structure to sputter an aluminum nitride film on a patterned substrate. Figure 4 As shown, in order to enable the aluminum atoms sputtered vertically from the surface of the micro-bevel structure to move directly to the step surface (that is, the side) of the patterned substrate, the angle between the side of the bevel structure and the surface of the patterned substrate is less than arctan (D / W), and the repetition period of the bevel structure is less than 2(L+D)tan(D / W)-W, where D is the depth of the substrate pattern, W is the width of the substrate pattern, and L is the target-base spacing.

[0064] In a specific application, the aforementioned triangular prism micro-bevel structure is used, and the angle between the micro-bevel structure and the overall surface of the aluminum target is set at 5-20°, and the bevel of the repeated microstructure is set at 0.5-1mm to ensure that the graphic surface of all substrate graphics has a good step coverage. In a specific application, in addition to the aforementioned structural parameters, the aluminum target has a lip portion set to 5N, a thickness of 14mm, and a diameter of 480mm.

[0065] To summarize the above schemes, in some embodiments of the present disclosure, in order to deposit a uniform aluminum nitride film everywhere on the patterned substrate, before performing the sputtering deposition process, the patterned substrate is first subjected to a high-temperature oxidation process under vacuum conditions (the vacuum pressure is 1×10 -3 -5×10 -3 Torr vacuum process pressure, the temperature of the substrate is controlled between 700-800℃, 30sccm of high-purity oxygen is introduced, and the high-temperature oxidation treatment is performed for 300s, so that a dense oxide layer is formed on the surface of the patterned substrate, and then a sputtering deposition treatment is performed (using the aforementioned target material with periodic microstructure, controlling the target base spacing to 3-4cm, the temperature of the aluminum target material to be above 600℃, controlling the nitrogen flow rate to 50-90sccm, the argon flow rate to 1-15sccm, and the chamber pressure to (1-5)×10 -4Torr or less, sputtering power of more than 6Kw, and patterning substrate temperature of 800-900°C, an aluminum nitride film with high step coverage and uniform distribution is formed on the patterning.

[0066] Figure 5 is a microscopic schematic diagram of forming an aluminum nitride film on a patterned substrate using the aforementioned process. Figure 6 This is a microscopic diagram of the existing process for forming an aluminum nitride film on the same patterned substrate. Figure 5 and Figure 6 It can be clearly seen that the film thickness uniformity of the aluminum nitride film formed by the process provided by the embodiment of the present disclosure on the patterned substrate is significantly higher than the film thickness uniformity of the aluminum nitride film formed by the existing process.

[0067] Through microscopic measurement, the scheme of this embodiment is adopted, in such Figure 5 The aluminum nitride film formed on the patterned substrate shown has a thickness of 123nm at the top of the pattern, 138nm in the middle of the pattern, 134nm at the root of the pattern, and 130nm on the substrate plane (that is, on the C-shaped surface of the aluminum oxide substrate). The mean value of the aforementioned thickness is 131.3nm, the standard deviation is 6.4nm, and the ratio of the standard deviation to the average thickness (the smaller the ratio, the better the film uniformity) is 4.9%. The aforementioned data is converted into step coverage, and the step coverage at the top of the pattern is 94.6%, the step coverage in the middle of the pattern is 106.2%, and the step coverage at the root of the pattern is 103.1%.

[0068] Using existing technology, Figure 6 The aluminum nitride film formed on the patterned substrate shown has a thickness of 740nm at the top of the pattern, 420nm in the middle of the pattern, 104nm at the root of the pattern, and 313nm in the substrate plane (note that in order to achieve a specific thickness at the root of the pattern, the aluminum nitride deposition thickness on the substrate plane has to be increased, and the duration of the entire deposition process is also prolonged, and the deposition thickness on the substrate plane is significantly higher). The mean value of the aforementioned thickness is 394.3nm, the standard deviation is 265.2nm, and the ratio of the standard deviation to the average thickness is 67.3%. The aforementioned data is converted into step coverage, with a step coverage of 236.4% at the top of the pattern, 134.2% in the middle of the pattern, and only 33.2% at the root of the pattern.

[0069] It should be noted that, in this article, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0070] The above are only specific embodiments of the present disclosure, so that those skilled in the art can understand or implement the present disclosure. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to these embodiments herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for depositing an aluminum nitride film on a patterned substrate, characterized in that: include: A magnetron sputtering vapor deposition process is used to perform sputtering deposition processing to deposit an aluminum nitride film on a patterned substrate; Wherein: the sputtered target is an aluminum target, and the patterned substrate is a sapphire substrate; The patterned substrate is kept grounded during the sputtering deposition process.

2. The method according to claim 1, characterized in that: During the sputtering deposition process, the flow rate ratio of nitrogen gas to argon gas is controlled to be between 3.3 and 6.0, and the specific nitrogen flow rate is determined according to the aspect ratio of the substrate pattern in the patterned substrate; Wherein: the specific nitrogen flow rate is used to make the step coverage of the patterned substrate reach at least a target step coverage rate, and the specific nitrogen flow rate is in a preset positive correlation with the aspect ratio of the substrate pattern.

3. The method according to claim 2, characterized in that The relationship between the specific nitrogen flow rate and the aspect ratio of the substrate pattern is: Where p is the step coverage, k is the proportionality coefficient, is the specific nitrogen flow rate, and AR is the step coverage rate.

4. The method according to any one of claims 1 to 3, characterized in that: The aluminum target material is a target material whose sputtered surface has a periodic micro-bevel structure; the micro-bevel structure is used to allow aluminum atoms sputtered from the surface of the aluminum target material to enter the substrate pattern in a direction that is not perpendicular to the surface of the patterned substrate; The inclination angle of the micro-bevel structure is determined according to the aspect ratio of the patterned substrate, and the periodic size of the micro-bevel structure is determined according to the size of the substrate pattern and the target base spacing between the aluminum target and the patterned substrate surface.

5. The method according to claim 4, characterized in that: The micro-bevel structure is a symmetrical triangular prism-shaped microstructure or a pyramid-shaped microstructure; The angle between the side of the micro-bevel structure and the surface of the patterned substrate is less than arctan(D / W), and the repetition period of the micro-bevel structure is less than 2(L+D)tan(D / W)-W, where D is the depth of the substrate pattern, W is the width of the substrate pattern, and L is the target-base spacing.

6. The method according to any one of claims 1 to 3, characterized in that: Before performing the sputtering deposition process on the aluminum target, the method further comprises: The patterned substrate is subjected to high-temperature oxidation treatment under vacuum conditions to form a surface oxide layer on the surface of the patterned substrate; the surface oxide layer has a structure different from that of the single-crystal aluminum oxide of the substrate.

7. The method according to any one of claims 1 to 3, characterized in that: Also includes: During the sputtering deposition process, the temperature of the patterned substrate is controlled between 800-900°C.

8. The method according to any one of claims 1 to 3, characterized in that: During the sputtering deposition process, the heating function of the chamber heater of the sputtering device is turned on, and the chamber heater is used to heat the aluminum target material to increase the initial energy of aluminum atoms formed by sputtering.

9. The method according to claim 8, characterized in that The chamber heater heats the aluminum target and sputters the aluminum target so that an average kinetic energy of aluminum atoms formed by sputtering is higher than 1000 eV.

10. The method according to claim 9, characterized in that: During the sputtering deposition process, the pressure of the sputtering equipment chamber is controlled to be (1-5)×10 -4 Torr or less, and control the target base distance from the aluminum target to the substrate to be 3-6 cm.

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