Single mask stack etching method for forming stepped structure

Abstract

The invention relates to a single mask stack etch method for forming a stepped structure. Methods, systems, and apparatus for semiconductor fabrication are described. A stack of materials may be formed on a semiconductor substrate. The stack of materials may include a first material, a second material, and a third material. A first etch operation may be performed. The first etch operation may remove a first portion of the first material. A second etch operation may be performed. The second etch operation may remove the first portion of the second material. A third etch operation may be performed. The third etch operation may remove the first portion of the third material. A fourth etch operation may be performed. A fourth etch operation may remove a second portion of the second material. A fifth etch operation may be performed. The fifth etch operation may remove a second portion of the first material.

Description

Technical Field

[0001] Example embodiments of the present disclosure generally relate to semiconductor devices and manufacturing techniques thereof. More specifically, the present disclosure relates to a single mask stack etching method for forming a staircase structure. Background Art

[0002] Some semiconductor devices may include layers of various materials stacked above a semiconductor substrate. Such semiconductor devices may be formed using various techniques, such as photolithography, etching, deposition, doping, and other techniques. Such techniques may be used to form various materials into patterns and configurations that enable the semiconductor device to operate. In some cases, a semiconductor device may include structures or materials that may be coupled to other devices (such as other semiconductor devices). For example, a semiconductor device may include one or more layers that are formed in a manner such that the semiconductor device may be coupled to another semiconductor device (e.g., via welding, via flip-chip bonding). Summary of the invention

[0003] Various embodiments described herein relate to methods, devices, and systems associated with a single mask stack etching method for forming a step structure. A method according to an embodiment includes forming a stack of materials on a semiconductor substrate, the stack of materials including a first material, a second material, and a third material; performing a first etching operation, wherein the first etching operation removes a first portion of the first material; performing a second etching operation, wherein the second etching operation removes a first portion of the second material; performing a third etching operation, wherein the third etching operation removes a first portion of the third material; performing a fourth etching operation, wherein the fourth etching operation removes a second portion of the second material; and performing a fifth etching operation, wherein the fifth etching operation removes the second portion of the first material.

[0004] The method according to an embodiment may further include forming a fourth material on a surface of the first material, wherein a position of the fourth material is stationary during the duration of the first etching operation, the second etching operation, the third etching operation, the fourth etching operation, and the fifth etching operation. In some cases, removing the first portion of the first material exposes a portion of a bottom surface of the fourth material including the photoresist layer, the portion of the bottom surface of the fourth material corresponding to an overhung region of the fourth material.

[0005] In some cases, removing the first portion of the second material exposes a portion of the bottom surface of the first material, the portion of the bottom surface of the first material corresponding to the overhang area of ​​the first material. In some cases, removing the first portion of the third material exposes a portion of the bottom surface of the second material, the portion of the bottom surface of the second material corresponding to the overhang area of ​​the second material. In some cases, removing the first portion of the first material, the first portion of the second material, and the first portion of the third material form an inverted staircase structure in the stack of materials. In some cases, removing the second portion of the second material and removing the second portion of the first material form a staircase structure in the stack of materials.

[0006] The method according to an embodiment may also include performing a rinse operation after the first etching operation, the second etching operation, the third etching operation, the fourth etching operation, and the fifth etching operation. In some cases, each of the first etching operation, the second etching operation, the third etching operation, the fourth etching operation, and the fifth etching operation includes an isotropic etching operation. In some cases, the first material includes silver, the second material includes nickel, and the third material includes titanium. Other technical features can be easily seen by those skilled in the art from the following drawings, descriptions, and claims.

[0007] In one aspect, a device includes: a first material of a stack of materials, the first material corresponding to a first step of a stepped structure formed using an isotropic etching operation, wherein a surface of the first step is parallel to an x-direction and a z-direction, and wherein a height of the first step is parallel to a y-direction; a second material of the stack of materials, the second material corresponding to a second step of the stepped structure, the second step of the stepped structure being located below the first step of the stepped structure relative to the y-direction, wherein the second step extends beyond an extent of the first step relative to the x-direction; and a third material of the stack of materials, the third material corresponding to a third step of the stepped structure, the third step of the stepped structure being located below the second step of the stepped structure relative to the y-direction, wherein the third step extends beyond an extent of the second step relative to the x-direction.

[0008] The device may also include a semiconductor substrate corresponding to a fourth step of the stepped structure, the semiconductor substrate being located below a third step of the stepped structure, wherein the fourth step extends beyond the range of the third step relative to the range of the x-direction. In some cases, the height of the second step of the stepped structure is greater than the height of the third step of the stepped structure. In some cases, the first material includes silver, the second material includes nickel, and the third material includes titanium. Other technical features can be easily seen by those skilled in the art from the following drawings, descriptions, and claims.

[0009] In one aspect, a product can be formed by a method that includes forming a stack of materials on a semiconductor substrate, the stack of materials including a first material, a second material, and a third material; performing a first etching operation, wherein the first etching operation removes a first portion of the first material; performing a second etching operation, wherein the second etching operation removes a first portion of the second material; performing a third etching operation, wherein the third etching operation removes a first portion of the third material; performing a fourth etching operation, wherein the fourth etching operation removes a second portion of the second material; and performing a fifth etching operation, wherein the fifth etching operation removes the second portion of the first material.

[0010] The method according to an embodiment may also include forming a fourth material on the surface of the first material, wherein the position of the fourth material is stationary during the duration of the first etching operation, the second etching operation, the third etching operation, the fourth etching operation, and the fifth etching operation. In some cases, removing the first portion of the first material exposes a portion of the bottom surface of the fourth material including the photoresist layer, and the portion of the bottom surface of the fourth material corresponds to the overhanging area of ​​the fourth material. In some cases, removing the first portion of the second material exposes a portion of the bottom surface of the first material, and the portion of the bottom surface of the first material corresponds to the overhanging area of ​​the first material.

[0011] In some cases, removing the first portion of the third material exposes a portion of the bottom surface of the second material, the portion of the bottom surface of the second material corresponding to the overhanging area of ​​the second material. In some cases, removing the first portion of the first material, the first portion of the second material, and the first portion of the third material form an inverted staircase structure in the stack of materials. In some cases, removing the second portion of the second material and removing the second portion of the first material form a staircase structure in the stack of materials. The method according to an embodiment may also include performing a rinse operation after the first etching operation, the second etching operation, the third etching operation, the fourth etching operation, and the fifth etching operation.

[0012] In some cases, each of the first etching operation, the second etching operation, the third etching operation, the fourth etching operation, and the fifth etching operation comprises an isotropic etching operation. In some cases, the first material comprises silver, the second material comprises nickel, and the third material comprises titanium. Other technical features can be easily seen by those skilled in the art from the following drawings, descriptions, and claims. In some cases, removing the second portion of the first material comprises removing at least the overhanging region of the first material. In some cases, removing the second portion of the second material comprises removing at least the overhanging region of the second material. In some cases, removing the second portion of the first material comprises removing at least the overhanging region of the first material. In some cases, removing the second portion of the second material comprises removing at least the overhanging region of the second material. Other technical features can be easily seen by those skilled in the art from the following drawings, descriptions, and claims.

[0013] The foregoing illustrative summary, as well as other exemplary objects and / or advantages of the present disclosure, will be further explained in the following detailed description and its accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The description of the illustrative embodiments may be read in conjunction with the accompanying drawings. It will be appreciated that, for simplicity and clarity of illustration, the elements shown in the figures are not necessarily drawn to scale unless otherwise described. For example, the dimensions of some of the elements may be exaggerated relative to other elements unless otherwise described. Embodiments incorporating the teachings of the present disclosure are shown and described with respect to the drawings presented herein, in which:

[0015] Figure 1 An example of a material arrangement supporting a single mask stack etching method for forming a step structure is illustrated;

[0016] Figure 2 An example of a material arrangement supporting a single mask stack etching method for forming a step structure is illustrated;

[0017] Figure 3 An example of a process flow supporting a single mask stack etching method for forming a step structure is illustrated;

[0018] Figure 4 An example of a process flow supporting a single mask stack etching method for forming a step structure is illustrated; and

[0019] Figure 5-Figure 6 An example of a flow chart supporting a single mask stack etching method for forming a step structure is illustrated. DETAILED DESCRIPTION

[0020] Some embodiments of the present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which some but not all embodiments of the present disclosure are shown. Indeed, these disclosures may be implemented in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that the present disclosure satisfies applicable legal requirements. Like reference numerals refer to like elements throughout the text.

[0021] As used herein, in the examples provided below, for the purpose of explanation, terms such as "front", "rear", "top", etc. are used to describe the relative positions of certain components or parts of components. In addition, based on this disclosure, it will be clear to one of ordinary skill in the art that the terms "substantially" and "approximately" indicate that the referenced element or associated description is accurate within applicable engineering tolerances.

[0022] As used herein, the term "comprising" means including but not limited to, and should be interpreted in the manner commonly used in the patent context. It should be understood that the use of broader terms such as "comprising," "including," and "having" provides support for narrower terms such as "consisting of," "consisting essentially of," and "consisting essentially of."

[0023] Phrases such as "in one embodiment," "according to one embodiment," etc. generally mean that a particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present disclosure and may be included in more than one embodiment of the present disclosure (importantly, such phrases are not necessarily referring to the same embodiment).

[0024] The word “example” or “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations.

[0025] If the specification states that a component or feature "may", "might", "could", "should", "will", "preferably", "likely", "usually", "optionally", "for example", "often", or "might" (or other such language) be included or have a property, then the particular component or feature is not required to be included or have the property. Such a component or feature may optionally be included in some embodiments, or it may be excluded.

[0026] Figure 1An example of a material arrangement 100 that supports a single mask stack etching method for forming a step structure in some examples is illustrated. In some cases, the material arrangement 100 may be an example of a portion of a semiconductor device or any other electronic device. The material arrangement 100 may be a device or a portion of a device for various applications such as automotive applications (e.g., for motor control, for charging modules). The material arrangement 100 may illustrate a cross-sectional view of a semiconductor device, in which some portions of the semiconductor device may be truncated or not shown. The material arrangement 100 may include one or more layers 105, each layer 105 may correspond to one or more different materials. Although some examples of specific materials or material compounds are described herein, the material arrangement 100 may include any combination of materials and material compounds. The material arrangement 100 may be oriented relative to a coordinate system or otherwise formed, such as Figure 1 For example, each layer 105 may have a width parallel to the x-direction, a depth parallel to the z-direction (eg, into the page), and a height parallel to the y-direction.

[0027] In one illustrative example, material arrangement 100 may include six layers 105, but any number of layers 105 may be used. For example, layer 105-e may be omitted from material arrangement 100, or other layers 105, such as silver layers, may be added. Material arrangement 100 may include layer 105-a (e.g., solder layer), layer 105-b (e.g., intermetallic compound (IMC) layer), layer 105-c (e.g., nickel layer), layer 105-d (e.g., titanium layer), layer 105-e (e.g., aluminum layer), and layer 105-f (e.g., silicon layer). Each layer 105 may be formed in contact with one or more other layers 105. In some cases, layer 105-f may be an example of a semiconductor substrate on which other layers 105 may be formed. For example, layer 105-e may be formed on layer 105-f. In some cases, one or more layers 105 may be formed as part of a metallization operation (e.g., final metallization may be performed using TiNiAg).

[0028] In some cases, material arrangement 100 may be formed using one or more operations such as photolithography, etching, deposition, doping, metallization, welding, or any other type of operation. In some cases, layer 105-e may be deposited on layer 105-f, layer 105-d may be deposited on layer 105-e, and layer 105-c may be deposited on layer 105-d. Although not shown, an additional layer 105 (e.g., a silver layer) may be deposited on layer 105-c and melted during the welding operation. That is, additional layer 105 may be an example of one or more components of layer 105-b. As described herein, material arrangement 100 may illustrate a stack of materials including one or more layers 105 that have been subjected to a welding operation or any other type of operation that results in the formation of layer 105-b (e.g., an IMC layer). Layer 105-b may be an example of a compound or mixture of one or more materials. For example, layer 105-b may include solder, silver, nickel, or any other combination of materials.

[0029] In some cases, material arrangement 100 may include one or more layers 105 for coupling layer 105-f (e.g., a semiconductor substrate) or layer 105-e (e.g., a redistribution layer) with circuitry of one or more other devices, such as another semiconductor device (not shown). For example, at least a portion of layer 105-b, layer 105-d, and layer 105-c may be examples of under-bump metallization (UBM), which may refer to a conductive portion of a semiconductor device that is located below a solder bump (e.g., layer 105-a). In such cases, material arrangement 100 may be an example of a plurality of material arrangements 100 for a semiconductor device.

[0030] In some cases, the thickness of one or more layers 105 (e.g., with respect to the y-direction) can be relatively large compared to other layers 105 (e.g., due to solder reflow constraints). For example, layer 105-c can be up to 2 micrometers (μm) thick, and layer 105-d can be up to 200 nanometers (nm) thick. However, increasing the thickness of layer 105-c can present one or more challenges. For example, material arrangement 100 can undergo one or more etching operations, which can create various mechanical instabilities that can be exacerbated by thickness differences between layers 105.

[0031] According to one or more examples as described herein, a staircase structure (e.g., a staircase pattern, a pyramid structure) can be formed in the material arrangement 100, which can improve the mechanical stability of the material arrangement 100 in some examples. The staircase structure can be formed using one or more etching operations (e.g., one or more spray wet etching operations, one or more isotropic etching operations), which can be relatively low cost compared to other types of etching operations (e.g., anisotropic etching operations, dry etching operations). The techniques described herein can utilize a single mask (e.g., a single resist layer), which can provide advantages over other techniques that require multiple masks or require mask realignment for each etching operation (e.g., for each material). The techniques described herein can include first forming an inverted staircase structure, and then performing one or more pull-back operations (e.g., one or more additional etching operations) to reverse the directionality of the inverted staircase structure (e.g., to form a staircase structure). For example, silver, nickel, and titanium layers can be sequentially etched to form an inverted staircase structure, and then the nickel and silver layers can be pulled back (e.g., using corresponding etching operations) to form the staircase structure. The single mask stack etching process may further include performing a rinsing operation after each respective etching operation and performing a final drying operation.

[0032] As described herein, the material arrangement 100 may be an example of a power device or a part of a power device. For example, the material arrangement 100 may be an example of a transistor (e.g., a power transistor) or a diode (e.g., a power diode). Such power devices may be capable of handling relatively high currents and relatively high voltages compared to other devices. In some cases, the material arrangement 100 may be an example of a power device (e.g., a transistor, a diode) included in a charging module for an electric vehicle. In addition, or alternatively, the material arrangement 100 may be an example of a power device (e.g., a transistor, a diode) included in a motor control module for an electric vehicle. In some cases, the material arrangement 100 may be an example of a bipolar junction transistor (BJT), a field effect transistor (FET), a metal oxide semiconductor field effect transistor (MOSFET), an insulated gate bipolar transistor (IGBT), a thyristor, or a silicon controlled rectifier (SCR).

[0033] Figure 2An example of a material arrangement 200 that supports a single mask stack etching method for forming a step structure is illustrated. As described herein, an inverted step structure can be formed in the material arrangement 200 (e.g., using one or more etching operations). In some cases, the inverted step structure can cause one or more types of instabilities, such as delamination, cracking, or any other type of instability, some of which can be illustrated by material arrangement 200-b, material arrangement 200-c, or material arrangement 200-d. In some cases, such instabilities can be caused or exacerbated by layer 205-c (e.g., a nitride layer), which can be larger or thicker than other layers 205 and, accordingly, can have a greater weight than other layers 205. According to the examples described herein, one or more etching operations can be performed to eliminate overhang regions associated with the inverted step structure, which can improve the mechanical strength and performance of the material arrangement 200. The material arrangements 200 can each be oriented relative to a coordinate system or otherwise formed, such as Figure 2 For example, each layer 205 may have a width parallel to the x-direction, a depth parallel to the z-direction (eg, into the page), and a height parallel to the y-direction.

[0034] Material arrangement 200 may include any number of layers 205, which may be formed using different materials. For example, material arrangement 200-a may include layer 205-a (e.g., a photoresist layer), layer 205-b (e.g., a silver layer), layer 205-c (e.g., a nickel layer), layer 205-d (e.g., a titanium layer), and layer 205-e (e.g., a silicon nitride layer). Each layer 205 may be formed in contact with one or more other layers 205. In some cases, layer 205-e may be an example of a semiconductor substrate on which other layers 205 may be formed. Material arrangement 200-a, material arrangement 200-b, material arrangement 200-c, and material arrangement 200-d may include one or more of the same layers 205, and may illustrate the same material arrangement 200 at different steps of a manufacturing process. For example, material arrangement 200-b, material arrangement 200-c, and material arrangement 200-d may illustrate material arrangement 200-a after layer 205-a is removed.

[0035] Each material arrangement 200 may be an example of a portion of a semiconductor device or any other electronic device. For example, the material arrangement 200 may illustrate an edge region of a semiconductor device in which an inverted staircase structure is formed using one or more manufacturing operations (such as one or more etching operations). As described herein, the phrase "inverted staircase structure" may refer to a region of the material arrangement 200 in which a portion of each layer 205 overhangs over a blank area (e.g., a portion of each layer 205 is not supported by or in contact with the underlying layer 205). For example, an edge or extent of layer 205-a with respect to the x-direction may extend beyond an edge or extent of layer 205-b, an edge or extent of layer 205-b with respect to the x-direction may extend beyond an edge or extent of layer 205-c, and so on.

[0036] In some cases, material arrangement 200 can be formed using one or more operations such as photolithography, etching, deposition, doping, metallization, welding, or any other type of operation. In some cases, layer 205-d can be deposited on layer 205-e, layer 205-c can be deposited on layer 205-d, layer 205-b can be deposited on layer 205-c, and layer 205-a can be deposited on layer 205-b. Although not shown, additional layers (e.g., aluminum layers) can be deposited on layer 205-e. As described herein, material arrangement 200 can illustrate a stack of materials including one or more layers 205 that have undergone one or more etching operations (e.g., one or more isotropic etching operations) to form an inverted staircase structure.

[0037] In some cases, various types of mechanical instabilities may lead to failure of material arrangement 200. Such mechanical instabilities may be caused by uneven weight distribution associated with layer 205-c, or more generally by uneven weight distribution associated with the overhang region. That is, the inverted step structure itself may be prone to some types of mechanical instabilities. Material arrangement 200-b illustrates an example of delamination between layer 205-d and layer 205-e. Material arrangement 200-c illustrates an example of cracking or breaking that may occur in layer 205-e. Material arrangement 200-d illustrates an example of cracking or breaking that may occur in layer 205-b and layer 205-c.

[0038] According to one or more examples as described herein, a staircase structure (e.g., a staircase pattern, a pyramid structure) can be formed in the material arrangement 200, which can improve the mechanical stability of the material arrangement 200. For example, the staircase structure can eliminate overhanging regions in the material arrangement 200, which can improve mechanical stability. In addition, eliminating overhanging regions in the material arrangement 200 can enable one or more key dimensions to be viewed when inspecting the material arrangement 200 from above. For example, the extent of each step in the staircase structure can be visible from above, which can enable some in-process inspections and correspondingly improve efficiencies associated with manufacturing.

[0039] The step structure can be formed using one or more etching operations (e.g., one or more wet etching operations, one or more isotropic etching operations), which is relatively low cost compared to other types of etching operations (e.g., anisotropic etching operations). The techniques described herein can utilize a single mask that can be formed using a single layer 205-a (e.g., a single resist layer). As described herein, using a single mask to form a step structure can provide advantages over other techniques that require multiple masks or require mask realignment for each etching operation (e.g., for each material). Such techniques can include first forming an inverted step structure, and then performing one or more pull-back operations (e.g., one or more additional etching operations) to reverse the directionality of the inverted step structure (e.g., to form a step structure). For example, layer 205-b, layer 205-c, and layer 205-d can be sequentially etched to form an inverted step structure, and then layer 205-c and layer 205-d can be pulled back (e.g., using corresponding etching operations) to form a step structure. The single mask stack etching process may further include performing a rinsing operation after each respective etching operation and performing a final drying operation.

[0040] Figure 3 An example of a process flow 300 supporting a single mask stack etching method for forming a staircase structure is illustrated. The process flow 300 may illustrate one or more aspects of the material arrangement 100 or the material arrangement 200 during a manufacturing operation. The process flow 300 may illustrate one or more layers 305, which may be examples of the layer 105 or the layer 205, as respectively referred to in Figure 1 and Figure 2As described. The last step of process flow 300 can illustrate an example of a staircase structure. For example, executing process flow 300 can result in the formation of a staircase structure including layer 305-b (e.g., a first step), layer 305-c (e.g., a first step), layer 305-d (e.g., a first step), and layer 305-e (e.g., a first step). In one illustrative example, layer 305-a can be formed of a UV-resistant material, layer 305-b can be formed of silver, layer 305-c can be formed of nickel, layer 305-d can be formed of titanium, and layer 305-e can be formed of silicon nitride. However, any other combination of materials can be used. For example, an aluminum layer can be added between layer 305-e and layer 305-d. Layer 305 can be oriented relative to a coordinate system or formed in other ways, such as Figure 3 For example, each layer 305 may have a width parallel to the x-direction, a depth parallel to the z-direction (eg, into the page), and a height parallel to the y-direction.

[0041] During the first stage (e.g., first step) of the manufacturing operation, a first etching operation (e.g., wet etching operation, isotropic etching operation) may be performed to remove a first portion of layer 305-b. The first portion of layer 305-b may be at least partially located below layer 305-a. For example, removing the first portion of layer 305-b may result in the formation of an overhang (e.g., a portion of layer 305-a may overhang an area where the first portion of layer 305-b has been removed). In some cases, the first etching operation may include depositing a first etching solution that selectively etches a specific material (e.g., silver). A single mask (e.g., layer 305-a) may be used as a guide for the first etching solution. For example, the amount of material removed from layer 305-b may be based on a single mask (e.g., the position or size of a single mask) and the duration of exposure of the etching solution to layer 305-b. In some cases, a first rinsing operation may be performed after the first etching operation. The first rinsing operation may remove contaminants, residues, or other materials.

[0042] During a second stage (e.g., a second step) of the manufacturing operation, a second etching operation (e.g., a wet etching operation, an isotropic etching operation) may be performed to remove a first portion of layer 305-c. The first portion of layer 305-c may be at least partially below layer 305-b. For example, removing the first portion of layer 305-c may result in the formation of an overhang (e.g., a portion of layer 305-b may overhang an area where the first portion of layer 305-c has been removed). In some cases, the second etching operation may include depositing a second etching solution that selectively etches a specific material (e.g., nickel). A single mask (e.g., layer 305-a) may be used as a guide for the second etching solution. In addition, or alternatively, a single mask may remain stationary (e.g., may not be repositioned) for the duration of the first etching operation and the second etching operation. In some cases, a second rinsing operation may be performed after the second etching operation. The second rinsing operation may remove contaminants, residues, or other materials.

[0043] During the third stage (e.g., the third step) of the manufacturing operation, a third etching operation (e.g., a wet etching operation, an isotropic etching operation) can be performed to remove the first portion of layer 305-d. The first portion of layer 305-d can be at least partially located below layer 305-c. For example, removing the first portion of layer 305-c can result in the formation of an overhang (e.g., a portion of layer 305-c can overhang an area where the first portion of layer 305-d has been removed). In some cases, the third etching operation can include depositing a third etching solution that selectively etches a specific material (e.g., titanium). A single mask (e.g., layer 305-a) can be used as a guide for the third etching solution. In addition, or alternatively, a single mask can remain stationary (e.g., may not be repositioned) for the duration of the first etching operation, the second etching operation, and the third etching operation. In some cases, a third rinsing operation can be performed after the third etching operation. The third rinsing operation can remove contaminants, residues, or other materials.

[0044] During a fourth stage (e.g., fourth step) (e.g., pullback step) of the manufacturing operation, a fourth etching operation (e.g., wet etching operation, isotropic etching operation) may be performed to remove a second portion of layer 305-c. The second portion of layer 305-c may include at least an overhanging portion of layer 305-c. For example, removing the second portion of layer 305-c may result in the elimination of the overhang. In some cases, the fourth etching operation may include depositing a second etching solution that selectively etches a specific material (e.g., nickel). A single mask (e.g., layer 305-a) may be used as a guide for the second etching solution. In addition, or alternatively, a single mask may remain stationary (e.g., may not be repositioned) for the duration of the first etching operation, the second etching operation, the third etching operation, and the fourth etching operation. In some cases, a fourth rinsing operation may be performed after the fourth etching operation. The fourth rinsing operation may remove contaminants, residues, or other materials.

[0045] During the fifth stage (e.g., fifth step) (e.g., pullback step) of the manufacturing operation, a fifth etching operation (e.g., wet etching operation, isotropic etching operation) may be performed to remove the second portion of layer 305-b. The second portion of layer 305-b may include at least an overhanging portion of layer 305-b. For example, removing the second portion of layer 305-b may result in the elimination of the overhang. In some cases, the fifth etching operation may include depositing a first etching solution that selectively etches a specific material (e.g., silver). A single mask (e.g., layer 305-a) may be used as a guide for the first etching solution. In addition, or alternatively, a single mask may remain stationary (e.g., may not be repositioned) for the duration of the first etching operation, the second etching operation, the third etching operation, the fourth etching operation, and the fifth etching operation. In some cases, a fifth rinsing operation may be performed after the fifth etching operation. The fifth rinsing operation may remove contaminants, residues, or other materials. In some cases, a drying operation may be performed after the fifth rinsing operation, and layer 305-a may be removed.

[0046] After completing the fifth stage of the manufacturing operation, a step structure can be formed in layer 305. For example, the surface of layer 305-c can be exposed. The exposed surface of layer 305-c can have dimension 310-a. In some cases, dimension 310-a can be between 10nm and 10μm. In addition, the surface of layer 305-d can be exposed. The exposed surface of layer 305-d can have dimension 310-b. In some cases, dimension 310-b can be between 10nm and 2μm. In one example, dimension 310-b can be smaller than dimension 310-a. In addition, each layer 305 can have a corresponding height along the y direction. In some examples, the height of layer 305-c can be greater than the height of layer 305-b and the height of layer 305-d. For example, the height of layer 305-c can be between 250nm and 2μm.

[0047] As described herein, a ladder structure (e.g., formed in material arrangement 100, formed in material arrangement 200) may be an example of a power device or a portion of a power device. For example, the ladder structure may be an example of a transistor (e.g., a power transistor) or a diode (e.g., a power diode). Such power devices may be capable of handling relatively high currents and relatively high voltages compared to other devices. In some cases, the ladder structure may be an example of a power device (e.g., a transistor, a diode) included in a charging module for an electric vehicle. In addition, or alternatively, the ladder structure may be an example of a power device (e.g., a transistor, a diode) included in a motor control module for an electric vehicle. In some cases, the ladder structure may be an example of a BJT, a FET, a MOSFET, an IGBT, a thyristor, or an SCR.

[0048] Figure 4 An example of a process flow 400 supporting a single mask stack etching method for forming a stepped structure is illustrated. The process flow 400 may include multiple steps for forming a semiconductor device. In some cases, the steps included in the process flow 400 may be performed in a single lithography level (e.g., using a single photoresist). The process flow 400 may be performed by one or more devices or machines specifically designed for semiconductor manufacturing. For example, one or more steps in the process flow 400 may be performed by a machine configured to perform a wet etching operation. In some cases, the steps of the process flow 400 may include one or more steps not shown. For example, in some examples, one or more interface oxidation management operations may be performed to avoid residues and filaments. In addition, or alternatively, one or more steps may be omitted from the process flow 400.

[0049] At 405, a stack of materials may be formed on a semiconductor substrate. The stack of materials may include a first material (e.g., silver), a second material (e.g., nickel), and a third material (e.g., titanium). Although some illustrative examples are described with reference to titanium, nickel, and silver, any combination of materials may be used (e.g., any metal suitable for brazing). For example, the operations described herein may be performed for any combination of titanium, nickel, copper, silver, and gold. In some cases (e.g., at or before 405), a fourth material may be formed on the surface of the first material. The fourth material may be a photoresist material or a masking material. In some cases, the position of the fourth material may be stationary during the duration of the first etching operation, the second etching operation, the third etching operation, the fourth etching operation, and the fifth etching operation.

[0050] At 410, a first etching operation may be performed. The first etching operation may be a wet etching operation and may result in isotropic material removal. The first etching operation may remove a first portion of the first material. In some cases, removing the first portion of the first material exposes a portion of a bottom surface of a fourth material (e.g., a masking material). The portion of the bottom surface of the fourth material may correspond to an overhanging region of the fourth material. At 415, a rinse operation may be performed.

[0051] At 420, a second etching operation may be performed. The second etching operation may be a wet etching operation and may result in isotropic material removal. The second etching operation may remove a first portion of the second material. In some cases, removing the first portion of the second material may expose a portion of the bottom surface of the first material. The portion of the bottom surface of the first material may correspond to an overhanging region of the first material. At 425, a rinse operation may be performed.

[0052] At 430, a third etching operation may be performed. The third etching operation may be a wet etching operation and may result in isotropic material removal. The third etching operation may remove a first portion of the third material. In some cases, removing the first portion of the third material may expose a portion of the bottom surface of the second material. The portion of the bottom surface of the second material may correspond to an overhanging region of the second material. In some cases, removing the first portion of the first material, the first portion of the second material, and the first portion of the third material may form an inverted step structure in the stack of materials. At 435, a flushing operation may be performed.

[0053] At 440, a fourth etching operation can be performed. The fourth etching operation can be a wet etching operation and can result in isotropic material removal. The fourth etching operation can remove a second portion of the second material. In some cases, removing the second portion of the second material can include removing at least an overhanging region of the second material. At 445, a rinse operation can be performed.

[0054] At 450, a fifth etching operation may be performed. The fifth etching operation may be a wet etching operation and may result in isotropic material removal. The fifth etching operation may remove a second portion of the first material. In some cases, removing the second portion of the first material may include removing at least an overhanging region of the first material. In some cases, removing the second portion of the second material and removing the second portion of the first material may form a stepped structure in the stack of materials. At 455, a rinsing operation may be performed, and a drying operation may be performed after the rinsing operation.

[0055] Figure 5 An example of a flow chart of a method 500 supporting a single mask stack etching method for forming a staircase structure is illustrated. The operations of method 500 may be implemented by a manufacturing system or machine configured to perform one or more operations as described herein. For example, a machine or manufacturing system configured to perform one or more etching operations may perform the operations of method 500. In some cases, the manufacturing system or machine may execute instructions to control one or more functional elements to perform the described operations. In addition, or alternatively, the machine or manufacturing system may use dedicated hardware to perform various aspects of the operations.

[0056] At 505, method 500 may include forming a stack of materials on a semiconductor substrate. The stack of materials may include a first material, a second material, and a third material. The operations may be performed according to examples as described herein. In some examples, aspects of the operations may be performed using a dedicated machine or manufacturing system.

[0057] At 510, method 500 may include performing a first etching operation. The first etching operation may remove a first portion of a first material. The operations may be performed according to examples as described herein. In some examples, aspects of the operations may be performed using a dedicated machine or manufacturing system.

[0058] At 515, method 500 may include performing a second etching operation. In some cases, the second etching operation may remove a first portion of the second material. The operations may be performed according to examples as described herein. In some examples, aspects of the operations may be performed using a dedicated machine or manufacturing system.

[0059] At 520, method 500 may include performing a third etching operation. The third etching operation may remove a first portion of the third material. The operations may be performed according to examples as described herein. In some examples, aspects of the operations may be performed using a dedicated machine or manufacturing system.

[0060] At 525, method 500 may include performing a fourth etching operation. The fourth etching operation may remove a second portion of the second material. The operations may be performed according to examples as described herein. In some examples, aspects of the operations may be performed using a dedicated machine or manufacturing system.

[0061] At 530, method 500 may include performing a fifth etching operation. The fifth etching operation may remove a second portion of the first material. The operations may be performed according to examples as described herein. In some examples, aspects of the operations may be performed using a dedicated machine or manufacturing system.

[0062] Figure 6 An example of a flow chart of a method 600 supporting a single mask stack etching method for forming a staircase structure is illustrated. The operations of method 600 may be implemented by a manufacturing system or machine configured to perform one or more operations as described herein. For example, a machine or manufacturing system configured to perform one or more etching operations may perform the operations of method 600. In some cases, the manufacturing system or machine may execute instructions to control one or more functional elements to perform the operations. In addition, or alternatively, the machine or manufacturing system may use dedicated hardware to perform various aspects of the operations.

[0063] At 605, method 600 may include forming a stack of materials on a semiconductor substrate. The stack of materials may include a first material, a second material, and a third material. The operations may be performed according to examples as described herein. In some examples, aspects of the operations may be performed using a dedicated machine or manufacturing system.

[0064] At 610, method 600 may include forming a fourth material on a surface of the first material. The location of the fourth material may be stationary during the duration of the first etching operation, the second etching operation, the third etching operation, the fourth etching operation, and the fifth etching operation. The operations may be performed according to the examples described herein. In some examples, aspects of the operations may be performed using a dedicated machine or manufacturing system.

[0065] At 615, method 600 may include performing a first etching operation. The first etching operation may remove a first portion of the first material. The operations may be performed according to examples as described herein. In some examples, aspects of the operations may be performed using a dedicated machine or manufacturing system.

[0066] At 620, method 600 may include performing a second etching operation. In some cases, the second etching operation may remove a first portion of the second material. The operations may be performed according to examples as described herein. In some examples, aspects of the operations may be performed using a dedicated machine or manufacturing system.

[0067] At 625, method 600 may include performing a third etching operation. The third etching operation may remove the first portion of the third material. The operations may be performed according to examples as described herein. In some examples, aspects of the operations may be performed using a dedicated machine or manufacturing system.

[0068] At 630, method 600 may include performing a fourth etching operation. The fourth etching operation may remove a second portion of the second material. The operations may be performed according to examples as described herein. In some examples, aspects of the operations may be performed using a dedicated machine or manufacturing system.

[0069] At 635, method 600 may include performing a fifth etching operation. The fifth etching operation may remove a second portion of the first material. The operations may be performed in accordance with examples as described herein. In some examples, aspects of the operations may be performed using a dedicated machine or manufacturing system.

[0070] Although this detailed description has set forth some embodiments of the present invention, the appended claims also cover other embodiments of the present invention, which may differ from the described embodiments according to various modifications and improvements. In the appended claims, unless the specific terms "means for..." or "step for..." are used in a given claim, it is not intended that the claims be interpreted in accordance with 35 U.S.C. 112, paragraph 6.

Claims

1. A method comprising: forming a stack of materials on a semiconductor substrate, the stack of materials comprising a first material, a second material, and a third material; performing a first etching operation, wherein the first etching operation removes a first portion of the first material; performing a second etching operation, wherein the second etching operation removes a first portion of the second material; performing a third etching operation, wherein the third etching operation removes the first portion of the third material; performing a fourth etching operation, wherein the fourth etching operation removes a second portion of the second material; as well as A fifth etch operation is performed, wherein the fifth etch operation removes the second portion of the first material.

2. The method of claim 1, further comprising: A fourth material is formed on a surface of the first material, wherein a location of the fourth material is stationary for a duration of the first etching operation, the second etching operation, the third etching operation, the fourth etching operation, and the fifth etching operation. 3 . The method of claim 1 , wherein removing the first portion of the first material exposes a portion of a bottom surface of a fourth material including the photoresist layer, the portion of the bottom surface of the fourth material corresponding to the overhang region of the fourth material.

4. The method of claim 1, wherein removing the first portion of the second material exposes a portion of the bottom surface of the first material, the portion of the bottom surface of the first material corresponding to the overhang region of the first material. 5 . The method of claim 4 , wherein removing the second portion of the first material comprises removing at least an overhanging region of the first material.

6. The method of claim 1, wherein removing the first portion of the third material exposes a portion of the bottom surface of the second material, the portion of the bottom surface of the second material corresponding to the overhang region of the second material.

7. The method of claim 6, wherein removing the second portion of the second material comprises removing at least an overhanging region of the second material.

8. The method of claim 1, wherein removing the first portion of the first material, the first portion of the second material, and the first portion of the third material forms an inverted staircase structure in the stack of materials.

9. The method of claim 1, wherein removing the second portion of the second material and removing the second portion of the first material form a step structure in the stack of materials.

10. The method of claim 1, further comprising: A rinsing operation is performed after the first etching operation, the second etching operation, the third etching operation, the fourth etching operation, and the fifth etching operation.

11. The method of claim 1, wherein each of the first etching operation, the second etching operation, the third etching operation, the fourth etching operation, and the fifth etching operation comprises an isotropic etching operation.

12. The method of claim 1, wherein the first material comprises silver, the second material comprises nickel, and the third material comprises titanium.

13. An apparatus comprising: a first material of the stack of materials, the first material corresponding to a first step of the staircase structure formed using the isotropic etching operation, wherein a surface of the first step is parallel to the x-direction and the z-direction, and wherein a height of the first step is parallel to the y-direction; a second material of the stack of materials, the second material corresponding to a second step of the stepped structure, the second step of the stepped structure being located below the first step of the stepped structure with respect to the y-direction, wherein the extent of the second step with respect to the x-direction extends beyond the extent of the first step; and A third material of the stack of materials corresponds to a third step of the stepped structure, the third step of the stepped structure being located below the second step of the stepped structure relative to the y-direction, wherein the extent of the third step relative to the x-direction extends beyond the extent of the second step.

14. The apparatus of claim 13, further comprising: A semiconductor substrate corresponding to a fourth step of the stepped structure is located below a third step of the stepped structure, wherein the fourth step extends beyond the range of the third step with respect to the range of the x-direction.

15. The device of claim 13, wherein a height of the second step of the stepped structure is greater than a height of the third step of the stepped structure.

16. The apparatus of claim 13, wherein the first material comprises silver, the second material comprises nickel, and the third material comprises titanium.

17. A product formed by a process comprising: forming a stack of materials on a semiconductor substrate, the stack of materials comprising a first material, a second material, and a third material; performing a first etching operation, wherein the first etching operation removes a first portion of the first material; performing a second etching operation, wherein the second etching operation removes a first portion of the second material; performing a third etching operation, wherein the third etching operation removes the first portion of the third material; performing a fourth etching operation, wherein the fourth etching operation removes a second portion of the second material; as well as A fifth etch operation is performed, wherein the fifth etch operation removes the second portion of the first material.

18. The product formed by the method of claim 17, further comprising: A fourth material is formed on a surface of the first material, wherein a location of the fourth material is stationary for a duration of the first etching operation, the second etching operation, the third etching operation, the fourth etching operation, and the fifth etching operation.

19. The product formed by the method of claim 17, wherein removing the first portion of the first material exposes a portion of a bottom surface of a fourth material including the photoresist layer, the portion of the bottom surface of the fourth material corresponding to the overhang region of the fourth material.

20. The product formed by the method of claim 17, wherein removing the first portion of the second material exposes a portion of the bottom surface of the first material, the portion of the bottom surface of the first material corresponding to the overhang region of the first material.

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