A TiN film morphology etching method and TiN film

Abstract

The present application belongs to the field of semiconductor integrated circuit technology, and particularly relates to an etching method and a TiN film layer of TiN film layer morphology. The method comprises: for the film layer to be etched, firstly, a silicon oxide film layer in the film layer to be etched is etched using a photoresist as a mask, so that the silicon oxide film layer is in a right eight-shaped shape; then, the silicon oxide film in the right eight-shaped shape is used as a mask, and the TiN film layer in the film layer to be etched is etched, so that the TiN film layer is in a right eight-shaped shape; further, the TiN film layer in the right eight-shaped shape is etched by a wet side etching, so that the TiN film layer is in a right trapezoidal shape, and the inner angle between the side of the TiN film layer and the top surface of the P-gallium nitride is between 85-90 degrees; after stripping the silicon oxide film, a film layer of the target TiN morphology is obtained. The contact area between the TiN layer and the p-GaN layer of the TiN film layer prepared by this method is large, which can reduce the leakage of the reverse Schottky junction composed of the TiN layer and the p-GaN, and ensure that it has a large turn-on voltage and strong anti-noise ability.

Description

Technical Field

[0001] The present application belongs to the field of semiconductor integrated circuit technology, and in particular relates to a TiN film morphology etching method and a TiN film. Background Art

[0002] High Electron Mobility Transistor (HEMT) is a commonly used device in microwave radio frequency, optoelectronics, power electronics and other fields.

[0003] There are various types of HEMTs, including GaN-based HEMTs. The gate structure of GaN-based HEMTs (i.e., HEMTGate) usually includes a TiN film layer, a GaN Gate, and a Si substrate. Among them, the GaN Gate includes p-GaN (p-type gallium nitride) / Al-GaN / GaN. In the HEMT Gate, TiN can form a reverse Schottky junction of metal and semiconductor with p-GaN, thereby improving the turn-on voltage and noise resistance of the HEMT Gate. In this reverse Schottky junction, the single-side distance between the TiN film layer and the p-GaN layer is 400+ / -100 angstroms.

[0004] At present, wet etching is usually used to manufacture the above-mentioned HEMT Gate. Since the bottom structure of the TiN material is loose and prone to side corrosion, the contact area between the TiN layer and the p-GaN layer is small, which increases the leakage of the reverse Schottky junction formed by TiN and p-GaN, thereby affecting the turn-on voltage and noise resistance of the Schottky junction. Summary of the invention

[0005] In view of this, the embodiments of the present application provide a TiN film layer morphology etching method and a TiN film layer to solve the problem in the prior art that the bottom structure of the TiN material is loose and prone to side corrosion, resulting in a small contact area between the TiN layer and the p-GaN layer, which increases the leakage of the reverse Schottky junction formed by TiN and p-GaN, thereby affecting the turn-on voltage and noise resistance of the Schottky junction.

[0006] A first aspect of an embodiment of the present application provides a method for etching a TiN film layer morphology, the method being performed based on a film layer to be etched, the film layer to be etched sequentially comprising a photoresist, a silicon oxide film layer, a TiN film layer and a P-gallium nitride film layer, the method comprising:

[0007] Using the photoresist as a mask, etching the silicon oxide film layer so that the silicon oxide film layer is in a square shape;

[0008] Using the silicon oxide film in the shape of a square figure eight as a mask, etching the TiN film layer so that the TiN film layer is in the shape of a square figure eight;

[0009] The TiN film layer in the shape of a right figure eight is etched laterally by a wet method, so that the TiN film layer has a right trapezoidal morphology, and the inner angle between the side surface of the TiN film layer and the top surface of the P-gallium nitride is between 85 and 90 degrees;

[0010] After stripping off the silicon oxide film, a film layer with a target TiN morphology is obtained.

[0011] In combination with the first aspect, in a first possible implementation manner of the first aspect, the etching of the silicon oxide film layer using the photoresist as a mask so that the silicon oxide film layer is in a regular eight-shaped shape includes:

[0012] Under the first control condition of the first dry etching machine, the silicon oxide film is dry-etched with a PR type photoresist as a mask, so that the silicon oxide film is in a regular eight-shaped shape under the first preset condition and the first preset angle.

[0013] In combination with the first possible implementation manner of the first aspect, in a second possible implementation manner of the first aspect, the first control condition includes:

[0014] The pressure is 100-350 mTorr, the power is 400-1000 W, the magnetic field is 10-50 Gauss, the gas flow rate of argon is 50-200 ml per minute, the gas flow rate of carbon hexafluoride is 50-200 ml per minute, the gas flow rate of trifluoromethane is 10-100 ml per minute, and the process time is 10-50 seconds;

[0015] The first preset condition includes: the single-side distance between the silicon oxide film and the TiN film layer is 1000 angstroms;

[0016] The first preset angle is 75-80 degrees.

[0017] In combination with the first aspect, in a third possible implementation manner of the first aspect, the step of etching the TiN film layer using the silicon oxide film in the shape of a regular figure eight as a mask so that the TiN film layer is in the shape of a regular figure eight includes:

[0018] Under the second control condition of the second dry etching machine, the TiN film layer is dry-etched using the silicon oxide film in a right-side-up shape as a mask, so that the TiN film layer is in a right-side-up shape under the second preset condition and the second preset angle.

[0019] In combination with the first aspect, in a fourth possible implementation manner of the first aspect, the second control condition includes:

[0020] The pressure is 5-25 mTorr, the upper electrode power is 250-550 watts, the lower electrode power is 150-450 watts, the gas flow rate of chlorine is 10-60 ml per minute, the gas flow rate of boron trichloride is 10-70 ml per minute, and the process time is 10-50 seconds;

[0021] The second preset condition includes: the single-side distance between the TiN film layer and the P-gallium nitride film is 1000 angstroms;

[0022] The second preset angle is 70-75 degrees.

[0023] In combination with the first aspect, in a fifth possible implementation manner of the first aspect, the wet side etching of the TiN film layer in a right-shaped figure eight shape is used to make the TiN film layer have a right trapezoidal morphology, and the inner angle between the side surface of the TiN film layer and the top surface of the P-gallium nitride is between 85 degrees and 90 degrees, including:

[0024] The TiN film layer in the shape of a right figure eight is laterally etched by a mixed acid wet method, so that the TiN film layer has a right trapezoidal morphology, and the inner angle between the side surface of the TiN film layer and the top surface of the P-gallium nitride is between 85 and 90 degrees;

[0025] The mixed acid solution includes a first mixed acid solution and a second mixed acid solution, wherein the first mixed acid solution is a mixed acid of ammonia water and hydrogen peroxide solution, and the second mixed acid solution is a mixed acid of sulfuric acid and hydrogen peroxide solution.

[0026] In combination with the first aspect, in a sixth possible implementation manner of the first aspect, the step of using a mixed acid solution wet method to laterally etch the TiN film layer in a square figure eight shape includes:

[0027] After the TiN film layer in the shape of a square figure eight is subjected to wet lateral etching using a first mixed acid, the TiN film layer in the shape of a square figure eight is subjected to wet lateral etching using a second mixed acid.

[0028] In combination with the first aspect, in a seventh possible implementation manner of the first aspect, the TiN film layer in the shape of a square figure eight is subjected to wet lateral etching using a first mixed acid, including:

[0029] Controlling the volume ratio of ammonia water to hydrogen peroxide in the first mixed acid to be 1:1-1:2;

[0030] The etching temperature is set to 60-125° C., the process time is set to 250-450 seconds, and the TiN film layer in the shape of a square figure is subjected to wet lateral etching.

[0031] In combination with the first aspect, in an eighth possible implementation manner of the first aspect, the second mixed acid is used to perform wet lateral etching on the TiN film layer in the shape of a square figure eight, including:

[0032] Controlling the volume ratio of sulfuric acid to hydrogen peroxide in the second mixed acid to be 5:1-10:1;

[0033] The etching temperature is set to 60-125° C., the process time is set to 250-450 seconds, and the TiN film layer in the shape of a square figure is subjected to wet lateral etching.

[0034] A second aspect of an embodiment of the present application provides a TiN film layer, the morphology of the TiN film layer being prepared by an etching method of the TiN film layer morphology.

[0035] Compared with the prior art, the embodiments of the present application have the following beneficial effects: for the film layer to be etched, firstly, a photoresist is used as a mask to etch the silicon oxide film layer in the film layer to be etched, so that the silicon oxide film layer is in a right figure eight shape; then, the silicon oxide film in the right figure eight shape is used as a mask to etch the TiN film layer in the film layer to be etched, so that the TiN film layer is in a right figure eight shape; further, the TiN film layer in the right figure eight shape is etched laterally by a wet method, so that the TiN film layer is in a right trapezoidal morphology, and the inner angle between the side surface of the TiN film layer and the top surface of the P-gallium nitride is between 85 and 90 degrees; after stripping off the silicon oxide film, a film layer with a target TiN morphology is obtained. In the present method, the silicon oxide film layer and the TiN film layer are etched twice in the first two times, so that the side surface of the TiN film layer is in a right-shaped structure relative to the top surface of the P-gallium nitride. When the TiN film layer is wet-etched again, the lateral side corrosion during the wet etching can be offset, thereby obtaining a target TiN film layer with a morphology that meets the requirements. This solves the problem in the traditional method that the bottom structure of the TiN material is loose and prone to side corrosion, resulting in a small contact area between the TiN layer and the p-GaN layer, which increases the leakage of the reverse Schottky junction formed by the TiN and p-GaN, thereby affecting the turn-on voltage and anti-noise capability of the Schottky junction. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0037] Figure 1 This is the final structure diagram of GaN Gate;

[0038] Figure 2It is a schematic diagram of the structure of the TiN film layer with an inner eight-shaped structure in the GaN Gate prepared by the traditional method;

[0039] Figure 3 It is a schematic diagram of a process of etching a TiN film morphology provided in an embodiment of the present application;

[0040] Figure 4 It is a structural schematic diagram of etching the film layer to be etched provided in an embodiment of the present application;

[0041] Figure 5 It is a schematic diagram of the morphological changes of the film layer to be etched during the etching process provided in an embodiment of the present application. DETAILED DESCRIPTION

[0042] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0043] In order to illustrate the technical solution described in this application, a specific embodiment is provided below for illustration.

[0044] The third generation of semiconductors has the characteristics of high temperature resistance, high voltage resistance, high power, and radiation resistance. It is mainly composed of compound silicon carbide SiC and gallium nitride GaN, which are suitable for high voltage and high power scenarios. It is the only choice for photovoltaic, ultra-high voltage transmission, and new energy vehicle chip control materials. The high electron mobility transistor (HEMT) made of the third generation wide bandgap semiconductor material gallium nitride GaN has the advantages of high breakdown voltage, large saturated output current, high temperature resistance, radiation resistance, and fast switching speed.

[0045] In a GaN-based HEMT device gate structure (HEMT Gate), it includes a TiN film layer, a GaN Gate and a Si substrate. Among them, the GaN Gate as the basic structure of the HEMT Gate includes p-type gallium nitride (p-GaN) / Al-GaN / GaN. In the HEMT Gate, by introducing TiN material into the surface layer of the p-GaN structure, a reverse Schottky junction of metal and semiconductor formed by TiN and p-GaN can be obtained.

[0046] It should be understood that in the process of forming the above-mentioned reverse Schottky junction, the morphology of the TiN film layer is the key to the entire HEMT Gate structure. Only when the morphology of the TiN film layer meets certain requirements can it form a reverse Schottky junction of metal and semiconductor with p-GaN, thereby playing a role in improving the turn-on voltage and anti-noise ability of the HEMT Gate. This certain requirement generally refers to the single-side distance between the TiN film layer and the p-GaN layer being 400+ / -100 angstroms, see Figure 1 In the related art, the morphology of the TiN film layer prepared by the traditional method is in the shape of an inward-facing triangle, see Figure 2 , which makes the contact area between the TiN film layer and the p-GaN film small, resulting in increased leakage, thus affecting the turn-on voltage and anti-noise capability of the above-mentioned reverse Schottky junction. It should be noted that, see Figure 2 The above-mentioned inward-facing structure can be understood as the width of the upper surface of the TiN film layer is greater than the width of its lower surface, and can also be limited to the inner angle between the side of the TiN film layer and the upper surface of the p-GaN film being an obtuse angle, such as Figure 2 as shown in .

[0047] Therefore, in response to the above problems, an embodiment of the present application provides an etching method for the morphology of a TiN film layer. This method firstly transforms the overall structure of the TiN film layer into a regular "X" structure by dry etching a silicon oxide film and a TiN film layer, so as to offset the lateral corrosion during wet etching, so that during further wet etching, the "X" structure in the traditional method will not be formed, thereby effectively solving the above problems.

[0048] It should be noted that the above-mentioned right-sided structure can be understood as the width of the upper surface of the TiN film layer is smaller than the width of its lower surface, and can also be limited to the inner angle between the side surface of the TiN film layer and the upper surface of the p-GaN film being an acute angle.

[0049] Figure 3 FIG. 1 is a schematic flow chart of a TiN film morphology etching method provided by an embodiment of the present application. Figure 3 As shown, the following steps are included:

[0050] S1. Using a first photoresist as a mask, etching the silicon oxide film layer on the film layer to be etched, so that the silicon oxide film layer is in a regular "eight" shape.

[0051] In one example, the film to be etched can be Figure 4 As shown in the figure, it includes a first photoresist (such as PR), a silicon oxide film (PEOX), a TiN film layer, a p-type gallium nitride film (p-GaN), an Al-GaN film, a GaN film and a bottom silicon film (Si) layer arranged in sequence from top to bottom.

[0052] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0053] In one example, the silicon oxide film is obtained by reacting silane and nitrous oxide, and the first photoresist may be a photoresist PR film layer.

[0054] In an example, etching the silicon oxide film layer to be etched using the first photoresist as a mask may include the following contents.

[0055] Under the first control condition of the first dry etching machine, the silicon oxide film layer is dry-etched with a PR type photoresist as a mask, so that the silicon oxide film layer is in a regular eight-shaped shape under the first preset condition and the first preset angle.

[0056] In this embodiment, the silicon oxide film (PEOX) in the film layer to be etched is first processed by a dry etching process, wherein the dry etching process uses a plasma generated by a low-pressure gas under a high-frequency electric field to bombard the substrate to achieve the effect of etching. Specifically, on the one hand, according to the different substrate materials, a suitable gas can be selected to react with the material to achieve the purpose of etching removal, and on the other hand, the electric field can be used to guide and accelerate the plasma so that it has a certain kinetic energy. When it bombards the surface of the substrate, it will knock out the material in the substrate, thereby achieving physical energy transfer to achieve the purpose of etching.

[0057] In an embodiment of the present application, when dry etching the silicon oxide film on the film layer to be etched, the first dry etching machine can select the dry etching machine model C5200 MxP of Applied Materials, and the selected first control conditions include: pressure of 100-350 mTorr, power of 400-1000 watts, magnetic field of 10-50 Gauss, argon gas flow rate of 50-200 ml per minute, carbon hexafluoride gas flow rate of 50-200 ml per minute, trifluoromethane gas flow rate of 10-100 ml per minute, and process time of 10-50 seconds.

[0058] The above parameters are set in the first dry etching machine, and the first preset condition is set in the dry etching machine, that is, the single-side distance between the silicon oxide film and the TiN film layer is 1000 angstroms, and the first preset angle, that is, the inner angle between the side of the silicon oxide film and the upper surface of the TiN film layer, in the embodiment of the present application, the first preset angle is 75-80 degrees. After the first dry etching in the first dry etching machine with the above parameter settings, the first etched film layer with an angle of 75-80 and a single-side distance between the silicon oxide film and the TiN film layer of 1000 angstroms can be obtained. Figure 5 Schematic diagram of the etching process shown in .

[0059] Please refer to the attached Figure 5 When the silicon oxide film on the film to be etched is etched, its morphology changes from Figure 5 The shape before dry carving is transformed into the shape after the first dry carving.

[0060] S2. Using the silicon oxide film in the shape of a regular "eight" as a mask, the TiN film layer to be etched is etched to make the TiN film layer in the shape of a regular "eight".

[0061] In this embodiment, the etching of the TiN film to be etched using the silicon oxide film in the shape of a square "X" as a mask may include the following method.

[0062] Under the second control condition of the second dry etching machine, the TiN film layer is dry-etched under the second preset condition with the silicon oxide film in a right-side-up shape as a mask, so that the TiN film layer is in a right-side-up shape under the second preset condition and the second preset angle.

[0063] In an embodiment of the present application, when the TiN film layer is dry-etched under the second preset conditions, the second dry-etching machine can select the Lam company's model 9600TCP dry-etching machine, and the selected second control conditions include: pressure of 5-25 mTorr, upper electrode power of 250-550 watts, lower electrode power of 150-450 watts, chlorine gas flow rate of 10-60 ml per minute, boron trichloride gas flow rate of 10-70 ml per minute, and process time of 10-50 seconds.

[0064] The above parameters are set in the second dry etching machine, and the second preset condition is set in the dry etching machine, that is, the single-side distance between the TiN film layer and the P-gallium nitride film is 1000 angstroms, and the second preset angle, that is, the inner angle between the side of the TiN film layer and the upper surface of the p-GaN film, in the embodiment of the present application, the second preset angle is 70-75 degrees. After the second dry etching in the second dry etching machine with the above parameter settings, the second etched film layer with an angle of 70-75 and a single-side distance between the TiN film layer and the P-gallium nitride film of 1000 angstroms can be obtained. Figure 5 Schematic diagram of the etching process shown in .

[0065] Please refer to the attached Figure 5 After the TiN film on the film to be etched is etched, its morphology changes from Figure 5 After the first dry engraving, it transforms into the shape after the second dry engraving.

[0066] Through the above dry etching process, the silicon oxide film and TiN film layer with a preset angle and a preset single-side distance can be obtained, which can provide a sufficient process window for the subsequent side corrosion of the TiN film layer. In the specific implementation, see Figure 5 As shown in the morphology after the second dry etching, the best effect is to obtain a silicon oxide film with a first preset angle of 80 degrees and a TiN film with a second preset angle of 75 degrees. If the morphology after dry etching is too straight, the side corrosion cannot be achieved without an inverted eight-shaped structure. Through two dry etchings of the PEOX film layer and the TiN film layer, the overall structure becomes inclined and presents a regular eight-shaped structure, which can offset the lateral side corrosion of the subsequent wet etching treatment, and ultimately will not form the inner eight-shaped structure in the traditional method.

[0067] S3. The TiN film layer in the shape of a right figure eight is etched laterally by a wet method, so that the TiN film layer has a right trapezoidal morphology, and the inner angle between the side surface of the TiN film layer and the top surface of the P-gallium nitride is between 85 and 90 degrees.

[0068] It should be noted that, in this embodiment, the above-mentioned regular trapezoid refers to Figure 5 The morphological structures of the PEOX film and TiN film layers are shown in FIG.

[0069] After the first two dry etchings are completed, in order to obtain the target TiN film morphology, the TiN film is further processed by wet etching. The wet process usually uses a suitable chemical solution to etch and remove the part of the material that is not covered by the photoresist (photosensitive film) to achieve a certain engraving depth.

[0070] In one implementation, the wet lateral etching process may be implemented by the following method.

[0071] The TiN film layer in the TiN film layer in the shape of a right figure eight is wet-etched by using a mixed acid solution, so that the TiN film layer has a right trapezoidal morphology, and the inner angle between the side surface of the TiN film layer and the top surface of the P-gallium nitride is between 85 and 90 degrees. The mixed acid solution includes a first mixed acid solution and a second mixed acid solution, the first mixed acid solution is a mixed acid of ammonia water and hydrogen peroxide (APM), and the second mixed acid solution is a mixed acid of sulfuric acid and hydrogen peroxide (SPM).

[0072] In one implementation of the embodiment of the present application, a mixed acid solution is used to wet-etch the TiN film layer in the second etching film layer, including:

[0073] After the TiN film layer in the second etching film layer is wet-etched with the first mixed acid (APM), the TiN film layer in the second etching film layer is wet-etched with the second mixed acid (SPM) to obtain a film layer with a target TiN morphology.

[0074] It should be noted that in the technical solution provided in the embodiments of the present application, when the wet etching process of TiN is completed by APM and SPM, in order to achieve a side corrosion thickness of 400+ / -100 angstroms and no inverted eight structure is produced, the wet etching sequence, acid solution ratio and wet etching time play a decisive role in the entire wet etching process. Therefore, when performing mixed acid etching, the order cannot be reversed.

[0075] In addition, since the inverted eight-shaped structure formed by APM etching alone is more serious than that formed by SPM etching, the wet etching process time of APM cannot be too long and needs to be strictly controlled within a certain range; the TiN film layer is easily passivated when etching by SPM, resulting in the TiN film layer being unable to achieve the corrosion effect. Therefore, when wet etching is performed by mixed acid solution, the SPM etching step needs to be performed after the APM etching, that is, the surface of the TiN film layer is first torn open by APM etching and then the TiN film layer is corroded by SPM. The required TiN morphology and side corrosion amount can be obtained by combining the two in a reasonably set time.

[0076] The specific process of wet etching the TiN film layer in the second etching film layer using the mixed acid solution in this embodiment is described in detail below.

[0077] In this embodiment, the TiN film layer in the second etching film layer is wet-etched using the first mixed acid, including: controlling the volume ratio of ammonia water and hydrogen peroxide in the first mixed acid to be 1:1-1:2. Setting the etching temperature to 60-125°C, setting the process time to 250-450 seconds, and wet-etching the TiN film layer in the second etching film layer.

[0078] In this embodiment, the TiN film layer in the second etching film layer is wet-etched using the second mixed acid, including:

[0079] The volume ratio of sulfuric acid to hydrogen peroxide in the second mixed acid is controlled to be 5:1-10:1.

[0080] The etching temperature is set to 60-125° C., the process time is set to 250-450 seconds, and the TiN film layer in the second etching film layer is wet-etched.

[0081] After wet etching is completed, you can get Figure 4 The TiN film layer after wet etching shown in FIG. 1 is in an almost vertical morphology, for example, the angle between the side surface of the TiN film layer and the top surface of the P-gallium nitride is between 85 and 90 degrees.

[0082] By adopting the wet process conditions and processing parameters provided in the examples of this application, the required TiN morphology and side corrosion amount can be obtained.

[0083] S4. After stripping off the silicon oxide film, a film layer with a target TiN morphology is obtained.

[0084] After the above two dry etching and mixed acid wet etching processes, the silicon oxide film in the GaN Gate structure is stripped off, and the following is obtained: Figure 1 The film layer with the required TiN morphology is shown in FIG.

[0085] In the etching method of the TiN film layer morphology provided in the embodiment of the present application, for the film layer to be etched, firstly, a photoresist is used as a mask to etch the silicon oxide film layer in the film layer to be etched, so that the silicon oxide film layer is in a right figure eight shape; then, the silicon oxide film in the right figure eight shape is used as a mask to etch the TiN film layer in the film layer to be etched, so that the TiN film layer is in a right figure eight shape; further, the TiN film layer in the right figure eight shape is etched laterally by a wet method, so that the angle between the side surface of the TiN film layer and the top surface of the P-gallium nitride is between 85 and 90 degrees; after stripping off the silicon oxide film, a film layer with a target TiN morphology is obtained. In the present method, the silicon oxide film layer and the TiN film layer are etched twice in the first two times, so that the side surface of the TiN film layer is in a right-shaped structure relative to the top surface of the P-gallium nitride. When the TiN film layer is wet-etched again, the lateral side corrosion during the wet etching can be offset, thereby obtaining a target TiN film layer with a morphology that meets the requirements. This solves the problem in the traditional method that the bottom structure of the TiN material is loose and prone to side corrosion, resulting in a small contact area between the TiN layer and the p-GaN layer, which increases the leakage of the reverse Schottky junction formed by the TiN and p-GaN, thereby affecting the turn-on voltage and anti-noise capability of the Schottky junction.

[0086] A second aspect of the embodiments of the present application provides a TiN film layer, the morphology of which is prepared by the etching method of the TiN film layer morphology provided in the above embodiments.

[0087] A third aspect of the embodiments of the present application provides a HEMT structure, comprising a TiN film layer prepared by the above-mentioned etching method of the TiN film layer morphology.

[0088] It should be noted that 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. It should be understood that when used in the specification of this application and the appended claims, the term "comprising" indicates the presence of the described features, wholes, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or their collections.

[0089] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0090] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A method for etching TiN film morphology, characterized in that: The method is performed based on a film layer to be etched, wherein the film layer to be etched sequentially includes a photoresist, a silicon oxide film layer, a TiN film layer and a P-gallium nitride film layer, and the method includes: Using the photoresist as a mask, etching the silicon oxide film layer so that the silicon oxide film layer is in a square shape; Using the silicon oxide film in the shape of a square figure eight as a mask, etching the TiN film layer so that the TiN film layer is in the shape of a square figure eight; After the TiN film layer in the shape of a square figure is subjected to wet lateral etching using a first mixed acid solution, the TiN film layer in the shape of a square figure is subjected to wet lateral etching using a second mixed acid solution, wherein the first mixed acid solution is a mixed acid of ammonia water and hydrogen peroxide, and the second mixed acid solution is a mixed acid of sulfuric acid and hydrogen peroxide; The volume ratio of ammonia water and hydrogen peroxide in the first mixed acid solution is controlled to be 1:1-1:2; the etching temperature is set to 60-125° C., the process time is set to 250-450 seconds, and the TiN film layer in the shape of a square figure is subjected to wet lateral etching; The volume ratio of sulfuric acid to hydrogen peroxide in the second mixed acid solution is controlled to be 5:1-10:1; the etching temperature is set to 60-125° C., the process time is set to 250-450 seconds, and the TiN film layer in the shape of a regular figure eight is subjected to wet lateral etching, so that the TiN film layer has a regular trapezoidal morphology, and the inner angle between the side surface of the TiN film layer and the top surface of the P-gallium nitride is between 85-90 degrees; After stripping off the silicon oxide film, a film layer with a target TiN morphology is obtained.

2. The method according to claim 1, characterized in that The method of etching the silicon oxide film layer using the photoresist as a mask so that the silicon oxide film layer is in a square shape includes: Under the first control condition of the first dry etching machine, the silicon oxide film is dry-etched with a PR type photoresist as a mask, so that the silicon oxide film is in a regular eight-shaped shape under the first preset condition and the first preset angle.

3. The method according to claim 2, characterized in that The first control conditions include: a pressure of 100-350 mTorr, a power of 400-1000 W, a magnetic field of 10-50 Gauss, an argon gas flow rate of 50-200 ml per minute, a carbon hexafluoride gas flow rate of 50-200 ml per minute, a trifluoromethane gas flow rate of 10-100 ml per minute, and a process time of 10-50 seconds; The first preset condition includes: the single-side distance between the silicon oxide film and the TiN film layer is 1000 angstroms; The first preset angle is 75-80 degrees.

4. The method according to claim 1, characterized in that: The method of etching the TiN film layer by using the silicon oxide film in the shape of a right triangle as a mask to make the TiN film layer in the shape of a right triangle includes: Under the second control condition of the second dry etching machine, the TiN film layer is dry-etched using the silicon oxide film in a right-side-up shape as a mask, so that the TiN film layer is in a right-side-up shape under the second preset condition and the second preset angle.

5. The method according to claim 4, characterized in that The second control conditions include: a pressure of 5-25 mTorr, an upper electrode power of 250-550 watts, a lower electrode power of 150-450 watts, a chlorine gas flow rate of 10-60 ml per minute, a boron trichloride gas flow rate of 10-70 ml per minute, and a process time of 10-50 seconds; The second preset condition includes: the single-side distance between the TiN film layer and the P-gallium nitride film is 1000 angstroms; The second preset angle is 70-75 degrees.

6. A TiN film, characterized in that: The morphology of the TiN film layer is prepared by the etching method of the TiN film layer morphology according to any one of claims 1-5.

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