Selective etching of scandium-doped aluminum nitride

Abstract

An exemplary substrate processing method is described. The method may include providing a scandium-doped aluminum nitride layer on a metal layer. The method may further include etching a portion of the scandium-doped aluminum nitride layer with an etching composition. The etching composition may include greater than or about 80 wt.% phosphoric acid. The composition may further have a temperature greater than or about 90ºC during etching.

Description

[Technical Field]

[0001] This disclosure claims the benefits of Indian Patent Application No. 202141039722, filed on 2 September 2021, the disclosure of which in its entirety is incorporated herein by reference for all purposes.

[0002] This technology relates to etching operations in substrate processing. More specifically, this technology relates to a method and structure for chemical etching of scandium-doped aluminum nitride in a piezoelectric structure. [Previous Technology]

[0003] Metal-insulator-metal (MIM) devices are made possible by processes that create intricately patterned material layers on a substrate surface. These processes include the formation of metal and insulating layers, allowing for the fabrication of micrometer-sized devices on the substrate, enabling physical actuation and processing of electronic signals. In many instances, the structure of such devices is formed by patterned etching operations, depositing one or more layers of metal, insulating, and piezoelectric materials patterned onto the substrate and into the device structure.

[0004] In many cases, etching operations use wet etchants, which can form openings, steps, and other structures into layers at the micrometer scale. Wet etchants typically etch significantly more material than gas or plasma etchants, making them more suitable for many situations requiring the rapid production of many types of MIM devices. However, wet etchants are more difficult to control during etching operations than dry and plasma etchants and can often over-etch the patterned layers. To control the probability and extent of over-etching, etching operations are typically tuned to a slower etch rate. Unfortunately, a slower etch rate results in longer etching times for MIM devices and reduced yields of patterned substrates.

[0005] Therefore, there is a need for improved systems and methods to produce high-quality MIM components and structures. These and other needs are addressed by this technology. [Summary of the Invention]

[0006] Embodiments of this technology include a substrate processing method, which includes providing a scandium-doped aluminum nitride layer on a metal layer. The method further includes etching a portion of the scandium-doped aluminum nitride layer with an etching composition. The etching composition is characterized by a temperature greater than or about 90ºC during etching.

[0007] In an additional embodiment, the etching composition is free of nitric acid. In a further embodiment, the etching composition is free of potassium hydroxide and tetramethylammonium hydroxide. Still in a further embodiment, the etching composition etches the scandium-doped aluminum nitride layer at an etch rate greater than or about 110 nm / min. Still in an additional embodiment, the etching composition etches the metal layer at an etch rate less than or about 1 nm / h. In many more embodiments, a patterned photoresist with one or more openings is formed on the scandium-doped aluminum nitride layer, and the etching composition etches a portion of the scandium-doped aluminum nitride layer through one or more openings in the patterned photoresist. Still in many more embodiments, the scandium-doped aluminum nitride layer comprises greater than or about 30 mol.% scandium. Still in a further embodiment, the metal layer comprises molybdenum.

[0008] Embodiments of this technology also include a substrate processing method, including providing a substrate. The substrate includes a scandium-doped aluminum nitride layer on a metal layer. The method also includes forming a patterned photoresist layer on the scandium-doped aluminum nitride layer, wherein the patterned photoresist layer includes one or more openings exposing a portion of the scandium-doped aluminum nitride layer. The method further includes contacting the substrate with an etching solution. The etching solution is characterized by a temperature greater than or about 90ºC and a phosphoric acid concentration greater than or about 80 wt.%. The method still further includes etching the exposed portions of the scandium-doped aluminum nitride layer with the etching solution.

[0009] In an additional embodiment, the etching solution is free of nitric acid, potassium hydroxide, and tetramethylammonium hydroxide. In a further embodiment, the etching solution is characterized by an etching rate greater than or about 10,000:1, where the selectivity for the scandium-doped aluminum nitride layer over the metal layer is superior. Still in a further embodiment, the etching solution etches the scandium-doped aluminum nitride layer at a first etching rate greater than or about 110 nm / min and etches the metal layer at a second etching rate less than or about 1 nm / h. In many more embodiments, the scandium-doped aluminum nitride layer comprises greater than or about 30 mol.% scandium. Still in many more embodiments, the metal layer comprises molybdenum.

[0010] Embodiments of this technology further include a structural substrate comprising a silicon-containing material and a first metal layer in contact with the silicon-containing material. The structural substrate may also include a patterned scandium-doped aluminum nitride layer in contact with the first metal layer, wherein the patterned scandium-doped aluminum nitride layer has a scandium content greater than or about 30 mol.%. The structural substrate may further include a patterned second metal layer in contact with a surface of the patterned scandium-doped aluminum nitride layer, the surface being relative to the surface in contact with the first metal layer.

[0011] In an additional embodiment, the silicon-containing material comprises a silicon oxide layer in contact with the first metal layer, and a silicon layer in contact with the silicon oxide layer. In a further embodiment, the structural substrate further comprises an undoped aluminum nitride layer in contact with the silicon-containing material and the first metal layer. Still in a further embodiment, the first metal layer may comprise unalloyed molybdenum. Still in a further embodiment, the second metal layer may comprise molybdenum. Still in many embodiments, the first metal layer lacks over-etched grooves above the gaps in the patterned scandium-doped aluminum nitride layer.

[0012] Embodiments of this technology offer several advantages over conventional techniques for forming MIM devices comprising piezoelectric materials, such as bulk acoustic wave elements. For example, embodiments of this technology allow for the formation of a highly selectively etched scandium-doped aluminum nitride (ScAlN) layer on a metal layer, which can function as an electrode for the piezoelectric ScAlN layer. Highly selective etching allows for complete etching of the ScAlN material down to the surface of the metal layer with little or no over-etching of the metal. The high selectivity of the etch composition allows for etching at increased temperatures, thereby increasing the etch rate, reducing the time required for the etching operation, and increasing the yield of patterned substrates. These and other embodiments, along with their many advantages and features, are described in more detail below and in conjunction with the accompanying drawings.

Implementation Method

[0025] A piezoelectric metal-insulator-metal (MIM) element comprises an electrically insulating layer of piezoelectric material positioned between a pair of electrically conductive metal layers forming electrodes of the element. Mechanical oscillations, such as acoustic waves, established in the piezoelectric material can cause a change in the material's electric field, which can propagate through the electrodes. Conversely, a change in the electric field applied to the piezoelectric material by the electrodes can establish mechanical oscillations in the piezoelectric material. The coupling between electrical and mechanical excitations in piezoelectric materials has several practical applications in electronic components. One such application is acoustic resonance, which allows MIM elements to function as multiplexed transmit and receive modules in mobile communication components. Modules made from such MIM materials can be reduced to the micrometer scale or smaller to establish very tight radio and microwave signal transmitters and receivers in mobile phones and other types of mobile components.

[0026] In other electronic applications, aluminum nitride (AlN) is the commonly used piezoelectric material in MIM components used for high-bandwidth mobile communications. Unfortunately, MIM component manufacturers have reached certain performance limits in terms of thermal stability and piezoelectric efficiency of undoped AlN. They have turned to doped AlN materials to overcome these limitations, and have specifically focused on scandium-doped aluminum nitride (ScAlN). Scandium doping increases the piezoelectric thermal stability of aluminum nitride and enhances additional piezoelectric properties, such as making the piezoelectric coefficient more power-efficient.

[0027] Increased scandium doping levels pose challenges to the efficient fabrication of MIM structures. The introduction of scandium into aluminum nitride renders alkaline wet etchants such as potassium hydroxide (KOH) and tetramethylammonium hydroxide (TMAH) less effective, especially when the underlying metal electrode layer includes molybdenum. Alkaline wet etchants exhibit low etch selectivity for heavily doped ScAlN relative to the underlying metal, and in many cases, the etching operation cannot be stopped before the metal layer and ScAlN material have been etched away together. Acidic wet etchants, such as those using phosphoric acid (H₃PO₄), become less effective with increasing scandium doping levels. Attempts to increase the efficiency of acidic wet etchants include combining phosphoric acid with nitric acid (HNO₃). However, introducing nitric acid into the phosphoric acid etch solution significantly reduces the selectivity for etching the ScAlN layer more than the adjacent metal layer, creating a low selectivity problem similar to that seen in alkaline wet etchants. Concerns about over-etching the ScAlN layer down to the underlying metal layer have led to etching operations being run at lower etch rates to better control the etching endpoint. The temperature of the phosphoric acid-containing etching solution is maintained at 85ºC or less to slow the ScAlN layer etch rate to 100 nm / min or less. Unfortunately, the reduced etch rate results in longer etch times for the etching operation. Etching operations through a 1-micron-thick ScAlN layer take longer than or about 10 minutes, resulting in low yields of the etched substrate.

[0028] Embodiments of this technology address the problem of low etching efficiency in wet etching compositions with low selectivity for etching scandium-doped aluminum nitride over adjacent metal lines. In this invention, it has been found that phosphoric acid etching solutions lacking additional strong inorganic acids such as nitric acid exhibit high selectivity for etching scandium-doped aluminum nitride over metal. Increasing the scandium doping level and incorporating molybdenum into the metal layer further increases the high etching selectivity. The high selectivity allows etching operations to be performed at high etching rates greater than or about 110 nm / min without concern that the etching solution will over-etch the ScAlN layer into the underlying metal layer. Faster etching rates are achieved by increasing the temperature of the etching solution to greater than or about 90ºC.

[0029] Embodiments of this technology significantly reduce the time required for ScAlN etching operations without significantly removing any underlying metal layers. In an embodiment, etching of a 1-micron-thick ScAlN layer can be completed in less than or about 5 minutes. This reduced etching time is achieved even when the scandium doping level in aluminum nitride is increased to greater than or about 30 mol.%. In an embodiment, the highly selective etching operation reduces the etching time to less than or about 50% of the time required for conventional wet etching operations with lower-temperature etching solutions.

[0030] Figure 1, according to an embodiment of the present technology, shows selected operations in a substrate processing method 100 for forming a patterned MIM structure. It should be understood that method 100 may include one or more operations prior to the initiation of the method, including front-end processing, deposition, etching, polishing, cleaning, and any operations that may be performed prior to said operations. Embodiments of method 100 may further include one or more optional operations that may or may not be specifically associated with said operations. For example, many of said operations may be performed in lieu of other operations and techniques, and are also covered within the scope of the present technology.

[0031] Figures 2A-F show partial cross-sectional views of the substrate structure 200 at various points during the operation of method 100. It should be understood that figures 2A-F only illustrate partial cross-sections, and the substrate structure may include any number of additional materials and features, having various properties and appearances, which are not shown in the figures. It should be understood that not all operations in method 100 can be fully represented in the substrate structure 200, and not all features shown in the substrate structure 200 can be implemented by the operations explicitly described in method 100.

[0032] Method 100 may include providing a substrate at operation 105. The provided substrate may be substrate 200 shown in Figure 2A, and includes a silicon-containing substrate layer 205, a first metal layer 210 in contact with the substrate layer 205, and a scandium-doped aluminum nitride layer 215 in contact with the first metal layer 210. The substrate 200 may also include a temporary, first photoresist layer 220 formed on the scandium-doped aluminum nitride layer 215.

[0033] In an embodiment, the silicon-containing substrate layer 205 may be made of one or more types of silicon, including polycrystalline silicon and monocrystalline silicon. In a further embodiment, the silicon-containing substrate layer 205 may include silicon oxide. Still in a further embodiment, silicon oxide may be formed or deposited on a silicon material such as polycrystalline silicon or monocrystalline silicon and other types of silicon. Still in an additional embodiment, the silicon-containing substrate layer 205 may be a base layer for a silicon wafer.

[0034] In an additional embodiment, the substrate 200 may optionally include an undoped aluminum nitride (AlN) layer positioned on the silicon-containing substrate layer 205. In an embodiment, the undoped AlN layer may serve as an adhesion layer between the silicon-containing substrate layer 205 and the first metal layer 210. In an additional embodiment, the undoped AlN layer may also serve as a seed layer for forming the first metal layer 210. In a further embodiment, the undoped AlN layer may be formed with a non-zero thickness of less than or about 200 nm, less than or about 175 nm, less than or about 150 nm, less than or about 125 nm, less than or about 110 nm, less than or about 100 nm, less than or about 90 nm, less than or about 80 nm, less than or about 70 nm, less than or about 60 nm, less than or about 50 nm, or less.

[0035] In a further embodiment, the first metal layer 210 may be made of one or more metals, such as molybdenum, aluminum, titanium, and other metals. The first metal layer 210 may serve as an electrode in a piezoelectric MIM structure. Still in a further embodiment, the first metal layer 210 may be made of non-alloyed molybdenum. Still in a further embodiment, the first metal layer 210 may have a non-zero thickness of less than or about 200 nm, less than or about 190 nm, less than or about 180 nm, less than or about 170 nm, less than or about 160 nm, less than or about 150 nm, or even less.

[0036] In an additional embodiment, the scandium-doped aluminum nitride layer 215 may form a patterned piezoelectric material in the MIM structure of the substrate 200. In an embodiment, layer 215 may include scandium doping at levels greater than or about 5 mol.%, greater than or about 10 mol.%, greater than or about 15 mol.%, greater than or about 20 mol.%, greater than or about 25 mol.%, greater than or about 30 mol.%, greater than or about 32.5 mol.%, greater than or about 35 mol.%, greater than or about 37.5 mol.%, greater than or about 40 mol.%, greater than or about 42.5 mol.%, greater than or about 45 mol.%, or more. In an additional embodiment, scandium may be uniformly distributed in the scandium-doped aluminum nitride layer 215. In further embodiments, scandium may have a gradient distribution in the scandium-doped aluminum nitride layer 215, wherein the surface of layer 215 in contact with metal layer 210 has a lower or higher scandium level than the surface of layer 215 facing the opposite contact surface. In further embodiments, the scandium-doped aluminum nitride layer 215 may have a thickness greater than or about 500 nm, greater than or about 600 nm, greater than or about 700 nm, greater than or about 800 nm, greater than or about 900 nm, greater than or about 1000 nm, or greater.

[0037] In further embodiments, a temporary photoresist layer 220 is formed on the scandium-doped aluminum nitride layer 215 to prepare for patterned etching of the ScAlN layer. The photoresist layer 220 may be made of a photosensitive organic polymer and is resistant to significant removal of wet etching components by means of the exposed portions of the scandium-doped aluminum nitride layer 215 via the patterned photoresist layer. In additional embodiments, the photoresist layer may comprise an epoxy-based photoresist material.

[0038] Method 100 further includes a patterned photoresist layer 220 at operation 110. In an embodiment, the patterning operation creates exposed portions on the surface of the scandium-doped aluminum nitride layer 215, and etching begins when the substrate 200 comes into contact with a wet etching solution. Figure 2B shows that patterned openings 225a-b are formed in the photoresist layer 220 as the photolithographic patterning operation is performed.

[0039] Method 100 further includes etching the scandium-doped aluminum nitride layer 215 at operation 115. Figure 2C shows that certain patterned openings 230a-b are formed in the scandium-doped aluminum nitride layer 215 upon completion of etching operation 115. The etching operation may include wet etching of the composition to contact the substrate 200, including a patterned photoresist layer 220. In embodiments, the wet etching composition may include phosphoric acid (H3PO4). In further embodiments, the concentration of phosphoric acid may be greater than or about 80 wt.%, greater than or about 81 wt.%, greater than or about 82 wt.%, greater than or about 83 wt.%, greater than or about 84 wt.%, greater than or about 85 wt.%, or more. The etching composition may not contain any compounds that reduce the etch selectivity of the composition relative to the metal layer 210 of the scandium-doped aluminum nitride layer 215. In embodiments, the etching composition may be free of other inorganic acids, such as nitric acid (HNO3), sulfuric acid (H2SO4), and hydrochloric acid (HCl), and other inorganic acids. In further embodiments, the etching composition may be free of organic acids, such as formic acid and acetic acid, and other organic acids. Still in additional embodiments, the etching composition may be free of basic compounds, such as potassium hydroxide (KOH), sodium hydroxide (NaOH), and tetramethylammonium hydroxide (TMAH), and other basic compounds. Still in many embodiments, the etching composition may be composed of phosphoric acid and water.

[0040] In an embodiment, the patterned substrate 200 and the etched composition can be contacted at an etched composition temperature greater than or about 90ºC. In an additional embodiment, the etched composition may have a contact temperature characterized by greater than or about 95ºC, greater than or about 100ºC, greater than or about 105ºC, greater than or about 110ºC, greater than or about 115ºC, greater than or about 120ºC, greater than or about 125ºC, greater than or about 130ºC, or greater. The increased temperature of the etched composition increases the etching rate of the scandium-doped aluminum nitride layer 215. In an embodiment, the etching operation 115 may be characterized by a ScAlN etching rate greater than or about 110 nm / min, greater than or about 120 nm / min, greater than or about 130 nm / min, greater than or about 140 nm / min, greater than or about 150 nm / min, greater than or about 160 nm / min, greater than or about 170 nm / min, greater than or about 180 nm / min, greater than or about 190 nm / min, greater than or about 200 nm / min, or greater.

[0041] Still in a further embodiment, the scandium-doped aluminum nitride layer 215, one micrometer thick, can be etched from the top surface in contact with the photoresist layer 220 to the bottom surface in contact with the metal layer 210 in less than or about 5 minutes, less than or about 4 minutes, less than or about 3 minutes, less than or about 2 minutes, or less. Conversely, a lower temperature etching composition characterized by a ScAlN etch rate of less than or about 100 nm / min at 85ºC or less will etch through the one micrometer thick layer 215 in more than or about 10 minutes. Embodiments of this technology can significantly shorten the etching operation time compared to etching operations using lower selectivity, lower temperature etching compositions. In embodiments, the etching operation can be less than or about half the time.

[0042] As described above, the high selectivity of the etching composition of scandium-doped aluminum nitride over the underlying metal in metal layer 210 allows for increased etch rates without over-etching the metal layer. In embodiments, the selectivity of the etching composition of the scandium-doped aluminum nitride layer 215 relative to the etching composition of metal layer 210 may be greater than or about 1000:1, greater than or about 5000:1, greater than or about 10,000:1, greater than or about 25,000:1, greater than or about 50,000:1, greater than or about 75,000:1, greater than or about 100,000:1, or greater. In further embodiments, the high selectivity of the etching composition is characterized by an etch rate of less than or about 10 nm / h, less than or about 5 nm / h, less than or about 1 nm / h, less than or about 0.5 nm / h, less than or about 0.1 nm / h, or less. In this embodiment, the low etch rate of the metal layer 210 of the etched composition avoids over-etched grooves in the exposed areas of the scandium-doped aluminum nitride layer 215.

[0043] Method 100 also includes forming a temporary, impedance layer 235 on the patterned scandium-doped aluminum nitride layer 215 at operation 120. As shown in Figure 2D, the impedance layer 235 may fill openings 230a-b in the patterned scandium-doped aluminum nitride layer 215 and cover the top surface of the patterned layer 215. In a further embodiment, the impedance layer 235 may be made of an organic polymer material or other material that avoids forming a second metal layer in areas not patterned on the impedance layer 235. Still in more embodiments, the impedance layer 235 may be a photoresist layer that can be photolithographically patterned at operation 125 for subsequently forming a patterned second metal layer on the patterned scandium-doped aluminum nitride layer 215.

[0044] Method 100 may further include forming a patterned second metal layer 240 at operation 130. Figure 2E shows a portion of the second metal layer 240 formed on a patterned scandium-doped aluminum nitride layer 215. Unremoved portions of the impedance layer 235 remaining after operation 125 prevent metal deposition in the second metal layer 240 from filling openings in the patterned scandium-doped aluminum nitride layer 215. In an additional operation, as shown in Figure 2F, the unremoved portions of the impedance layer 235 are removed to form a MIM structure in the substrate 200. In embodiments, the second metal layer 240 may be made of one or more metals, such as molybdenum, aluminum, titanium, platinum, and ruthenium, and other metals. In further embodiments, the second metal layer 240 may be made of the same metal as the first metal layer 210. In a further embodiment, the second metal layer 240 may have an average surface roughness of less than or about 10 nm, less than or about 9 nm, less than or about 8 nm, less than or about 7 nm, less than or about 6 nm, less than or about 5 nm, less than or about 4 nm, less than or about 3 nm, less than or about 2 nm, less than or about 1 nm, or even smaller.

[0045] Embodiments of this method can form a MIM element as shown in Figure 3A. In an embodiment, element 300 may include a base substrate 302 and includes a silicon layer 304, a silicon oxide layer 306, an aluminum nitride adhesive layer 308, and a first molybdenum metal layer 310. In a further embodiment, a patterned scandium-doped aluminum nitride layer 312 and a second molybdenum metal layer 314 are deposited and etched according to an embodiment of this method. Figure 3A marks a first region "A" in element 300, which includes the base substrate 302 but does not have a covering scandium-doped aluminum nitride layer 312 or a second molybdenum metal layer 314. The figure also marks a second region "B", which includes the base substrate 302 and a portion of the patterned scandium-doped aluminum nitride layer 312, but without the second molybdenum metal layer 314. The diagram further designates the third region "C", which includes all three base substrates 302, a portion of the patterned scandium-doped aluminum nitride layer 312, and a portion of the second, molybdenum metal layer 314. Cross-sections of regions "A", "B", and "C" are shown in Figure 3B.

[0046] Embodiments of this technology provide highly selective etching operations for scandium-doped aluminum nitride layers. Highly selective etching reduces over-etching of the ScAlN material into the adjacent metal layer. Furthermore, highly selective etching allows the operation to proceed at an increased etch rate without concern for extensive over-etching in the metal layer. In embodiments, the etching operation can form a patterned scandium-doped aluminum nitride layer with precisely formed etch stops at the exposed surfaces of the underlying metal layer. The etching operation can be performed in significantly less time than conventional etching operations that concern over-etching. In many cases, the etching operation according to this technology is performed in less than half the time of conventional etching operations.

[0047] In the foregoing description, several details have been mentioned for illustrative purposes to provide an understanding of various embodiments of the present technology. However, it will be apparent to those skilled in the art that certain embodiments are practicable without certain such details or with additional details. For example, other substrates that can benefit from the described wet process technology can also be used with the present technology.

[0048] Several embodiments have been disclosed, and those skilled in the art will recognize that various modifications, alternative constructions, and equivalents can be used without departing from the spirit of the embodiments. Furthermore, several known processes and elements have not been described in order to avoid unnecessarily obscuring the technology. Therefore, the above description should not be considered as limiting the scope of the technology.

[0049] When a range of values ​​is provided, it should be understood that, unless otherwise clearly indicated in the text, the various intermediate values ​​of the minimum fraction of the lower limit unit between the upper and lower limits of the range are also specifically disclosed. Any narrower range considering any stated value or unstated intermediate value in the range, and any other stated or intermediate value in the range. The upper and lower limits of such narrower ranges may be independently included or excluded in the range, and the various ranges of any limit value, non-limit value, or both limits included in the narrower range are also considered in the art and subject to any specifically excluded limit value in the range. When the range includes one or two limits, it also includes ranges excluding any or both of these included limits. When multiple values ​​are provided in a form, any range covering or based on any of such values ​​is similarly specifically disclosed.

[0050] As used herein and in the accompanying claims, the singular forms of “a,” “one,” and “the” include the plural references unless otherwise clearly indicated in the text. Thus, for example, reference to “a material” includes a plural of such materials, and reference to “the time period” includes reference to one or more time periods known to those skilled in the art, and their equivalents, and so on.

[0051] Moreover, when the words “comprising,” “containing,” “containing,” “covering,” “including,” and “including” are used in this specification and in the following requests, they are intended to indicate the presence of the stated features, numbers, components, or operations, but do not exclude the presence or addition of one or more other features, numbers, components, operations, actions, or groups. [Simplified Explanation of the Diagram]

[0013] A further understanding of the nature and advantages of the embodiments disclosed herein can be achieved by referring to the remainder of the specification and drawings.

[0014] Figure 1 shows an example operation of a method for selectively etching scandium-doped aluminum nitride material according to an embodiment of the present technology.

[0015] Figure 2A shows a partial cross-sectional view of a substrate structure according to an embodiment of the present technology.

[0016] Figure 2B shows another partial cross-sectional view of the substrate structure according to an embodiment of the present technology.

[0017] Figure 2C shows another partial cross-sectional view of the substrate structure according to an embodiment of the present technology.

[0018] Figure 2D shows another partial cross-sectional view of the substrate structure according to an embodiment of the present technology.

[0019] Figure 2E shows another partial cross-sectional view of the substrate structure according to an embodiment of the present technology.

[0020] Figure 2F shows another partial cross-sectional view of the substrate structure according to an embodiment of the present technology.

[0021] Figure 3A shows a plan view of a portion of a MIM element according to an embodiment of the present technology.

[0022] Figure 3B shows a cross-sectional view of a region of a MIM element according to an embodiment of the present technology.

[0023] Several diagrams are included as an overview. It should be understood that the diagrams are for illustrative purposes and should not be considered in terms of scale unless the scale is specifically stated. Furthermore, as an overview, the diagrams are provided to aid understanding and should not include all states or information compared to actual representations, and exaggerated material may be included for illustrative purposes.

[0024] In the drawings, similar parts and / or features may have the same element symbol. Furthermore, various parts of the same type may be marked by element symbols followed by letters, which are used to mark similar parts and / or features. If only the first element symbol is used in the specification, the description may be applied to any similar parts and / or features having the same first element symbol, regardless of the suffix letter. [Biomaterial Storage]

[0053] Domestic storage information (please note in order of storage institution, date, and number): None. International storage information (please note in order of storage country, institution, date, and number): None.

Claims

1. A substrate processing method comprising the steps of: providing a scandium-doped aluminum nitride layer on a metal layer; etching a portion of the scandium-doped aluminum nitride layer with an etching composition, wherein the etching composition contains greater than or about 80 wt.% phosphoric acid, and wherein the etching composition is characterized by a temperature greater than or about 90ºC during etching.

2. The substrate processing method as described in claim 1, wherein the etched composition does not contain nitric acid.

3. The substrate processing method as described in claim 1, wherein the etching composition does not contain potassium hydroxide and tetramethylammonium hydroxide.

4. The substrate processing method as claimed in claim 1, wherein the etching composition etches the scandium-doped aluminum nitride layer at an etching rate greater than or about 110 nm / min.

5. The substrate processing method as claimed in claim 1, wherein the etching composition etches the metal layer at an etching rate of less than or about 1 nm / hour.

6. The substrate processing method as claimed in claim 1, wherein a patterned photoresist having one or more openings is formed on the scandium-doped aluminum nitride layer, and wherein the etching composition etches the portion of the scandium-doped aluminum nitride layer through the one or more openings in the patterned photoresist.

7. The substrate processing method as described in claim 1, wherein the scandium-doped aluminum nitride layer contains more than or about 30 mol.% scandium.

8. The substrate processing method as described in claim 1, wherein the metal layer comprises molybdenum.

9. A substrate processing method comprising the steps of: providing the substrate, the substrate including a scandium-doped aluminum nitride layer on a metal layer; forming a patterned photoresist layer on the scandium-doped aluminum nitride layer, wherein the patterned photoresist layer includes one or more openings exposing a portion of the scandium-doped aluminum nitride layer; contacting the substrate with an etching solution, wherein the etching solution is characterized by a temperature greater than or about 90ºC and a phosphoric acid concentration greater than or about 80 wt.%; and etching the exposed portion of the scandium-doped aluminum nitride layer with the etching solution.

10. The substrate processing method as described in claim 9, wherein the etching solution is free of nitric acid, potassium hydroxide and tetramethylammonium hydroxide.

11. The substrate processing method as claimed in claim 9, wherein the etching solution is characterized by an etching rate selectivity ratio of greater than or about 10,000:1 for the scandium-doped aluminum nitride layer than for the metal layer.

12. The substrate processing method as claimed in claim 9, wherein the etching solution etches the scandium-doped aluminum nitride layer at a first etching rate greater than or about 110 nm / min and etches the metal layer at a second etching rate less than or about 1 nm / h.

13. The substrate processing method as described in claim 9, wherein the scandium-doped aluminum nitride layer contains more than or about 30 mol.% scandium.

14. The substrate processing method as described in claim 9, wherein the metal layer comprises molybdenum.

15. A structural substrate comprising: a silicon-containing material; a first metal layer in contact with the silicon-containing material; a patterned scandium-doped aluminum nitride layer in contact with the first metal layer, wherein the patterned scandium-doped aluminum nitride layer has a scandium content greater than or about 30 mol.%; and a patterned second metal layer in contact with a surface of the patterned scandium-doped aluminum nitride layer, the surface being relative to the surface in contact with the first metal layer.

16. The structural substrate as claimed in claim 15, wherein the silicon-containing material comprises a silicon monoxide layer in contact with the first metal layer and a silicon layer in contact with the silicon monoxide layer.

17. The structural substrate as claimed in claim 15, wherein the structural substrate further comprises an undoped aluminum nitride layer in contact with the silicon-containing material and the first metal layer.

18. The structural substrate as claimed in claim 15, wherein the first metal layer comprises non-alloyed molybdenum.

19. The structural substrate as claimed in claim 15, wherein the second metal layer comprises molybdenum.

20. The structural substrate as claimed in claim 15, wherein the first metal layer lacks an over-etched groove above a gap in the patterned scandium-doped aluminum nitride layer.

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