Semiconductor structure

Abstract

Device structures and methods of forming the same are provided. A semiconductor structure according to the present disclosure includes a first electrode and a second electrode disposed over a substrate, a heating element disposed over the substrate, a phase change material layer disposed over the substrate, and an insulator vertically disposed between the heating element and the phase change material layer. The phase change material layer at least comprises a first segment and a second segment separated from the first segment. In a top view, each of the first and second segments overlaps the heating element. Each of the first and second segments is electrically connected to the first and second electrodes.

Description

Technical Field

[0001] The embodiments of the utility model relate to a semiconductor structure. Background Art

[0002] In recent years, semiconductor devices based on phase-change materials (PCM) have emerged, for example in the field of phase-change memory devices as a promising alternative to nonvolatile memory (NVM) devices and in the field of radio frequency (RF) communications as RF switching devices are needed. The core of the PCM structure is a phase change element that exhibits switching behavior between a high-resistance amorphous phase and a low-resistance crystalline phase. Although existing PCM structures and processes for forming them are generally adequate for their intended purposes, they are not satisfactory in all respects. Utility Model Content

[0003] An embodiment of the utility model provides a semiconductor structure, comprising a first electrode and a second electrode arranged on a substrate; a heating element arranged on the substrate; a phase change material layer arranged on the substrate and an insulator vertically arranged between the heating element and the phase change material layer, wherein the phase change material layer at least comprises a first segment and a second segment separated from the first segment; each of the first and second segments overlaps with the heating element in a top view; and each of the first and second segments is electrically connected to the first and second electrodes.

[0004] An embodiment of the utility model provides a semiconductor structure, comprising a first electrode and a second electrode spaced apart along a first direction; a phase change material layer spanning and contacting the first electrode and the second electrode, the phase change material layer comprising a plurality of segments spaced apart along a second direction perpendicular to the first direction; a metal feature overlapping the phase change material layer, the metal feature extending longitudinally along the second direction; and an insulator vertically arranged between the phase change material layer and the metal feature. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The various aspects of the present invention will be best understood by reading the following detailed description in conjunction with the accompanying drawings. It should be noted that, according to standard practice in the industry, various features are not drawn to scale. In fact, the size of various features may be arbitrarily increased or reduced for clarity of discussion.

[0006] Figure 1 A flow chart of a method 100 of forming a PCM structure according to various aspects of the present disclosure is shown.

[0007] Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 , Fig. 9 , Fig.10 , Fig.11 , Fig.13 , Fig.14A , Fig. 14B and Fig. 14C The process according to various embodiments of the present disclosure is shown. Figure 1 Cross-sectional views of a workpiece during various operations of method 100 .

[0008] Figure 8 , Fig.12 , Fig.15 , Fig.16 , Fig.17 , Fig.18 , Fig.19 , Fig. 20 , Fig.21 , Fig. 22 , Fig.23 and Fig.24 The experience according to various embodiments of the present disclosure is shown Figure 1 FIG. 1 is a top view of a PCM structure for various operations of method 100 .

[0009] [Explanation of Symbols]

[0010] 100: Methods

[0011] 102, 104, 106, 108, 110, 112, 114, 116, 118, 120, 122: Blocks

[0012] 200: Artifact / PCM structure

[0013] 200-1: First PCM structure

[0014] 200-2: Second PCM structure

[0015] 202: Intermetallic dielectric layer

[0016] 204: Etch stop layer

[0017] 206, 226: Metal layer

[0018] 208: Insulator layer

[0019] 210: Heating element

[0020] 212: Insulator

[0021] 214, 222, 230: Mask layer

[0022] 216, 224, 238: Dielectric layer

[0023] 218: Phase change material layer

[0024] 220: Phase change element

[0025] 220a, 220b, 220c, 220d, 220e, 220f: fragment

[0026] 228: Electrode

[0027] 232: Opening

[0028] 234: Common Part

[0029] 236: Extension arm / arm

[0030] 240: Contact structure

[0031] 242: Through hole

[0032] 244: Metal Wire

[0033] D0: Distance

[0034] H1, H2, H3: Thickness

[0035] L1, L2, L3, L0: Length

[0036] PORT 1: First port

[0037] PORT 2: Second port

[0038] PORT 3: The third port

[0039] PORT 4: The fourth port

[0040] S0, S1, S2, S3: Interval

[0041] T c , T0: reference temperature point

[0042] W h , W h ', W0, W e , W1, W2, W3: Width

[0043] X, Y, Z: direction DETAILED DESCRIPTION

[0044] The following disclosure provides many different embodiments or examples for realizing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. Of course, these are merely examples and are not restrictive. For example, forming a first feature on or on a second feature in the following description may include an embodiment in which the first and second features are formed in direct contact, and may also include an embodiment in which an additional feature may be formed between the two so that the first feature may not be in direct contact with the second feature. In addition, the present disclosure may repeat reference numbers and / or letters in various examples. This repetition is for the purpose of simplicity and clarity, and does not itself specify the relationship between the various embodiments and / or configurations discussed.

[0045] For ease of description, spatially relative terms such as "below," "beneath," "lower," "above," "upper," and the like may be used herein to describe the relationship of one element or feature to another element or feature as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0046] In addition, when "about," "approximately," etc. are used to describe a number or a range of numbers, the term is intended to cover numbers within a reasonable range taking into account variations that are inherent in the manufacturing process as understood by those skilled in the art. For example, based on known manufacturing tolerances associated with manufacturing features having properties associated with the number, the number or range of numbers includes a reasonable range that includes the described number, such as within + / -10% of the described number. For example, a material layer having a thickness of "about 5 nm" may include a size range from 4.5 nm to 5.5 nm, where the manufacturing tolerance associated with the deposited material layer is known to those skilled in the art as + / -10%. Further, the present disclosure may repeat reference numbers and / or letters in various examples. Such repetition is for the purpose of simplicity and clarity and does not in itself dictate the relationship between the various embodiments and / or configurations discussed.

[0047] The present disclosure generally relates to semiconductor devices (or structures) based on phase change materials (PCMs) and methods for forming the same. PCM structures are based on the reversible switching behavior of phase change elements made of phase change materials (e.g., chalcogenide materials). At different temperatures, the phase change material can switch between a low-resistance crystalline phase (or state) and a high-resistance amorphous phase (or state). Because the resistivity ratio of the phase change material in the amorphous phase and the crystalline phase is generally greater than 1000, the PCM structure can be used as a switch. The PCM structure has multiple operational and engineering advantages, including high speed, low power consumption, non-volatility, high density, ready for process integration, and low cost.

[0048] Phase change materials are programmed based on the difference between the resistivity of a material in its amorphous and crystalline phases. Phase change materials are stable in both the crystalline and amorphous phases over a certain temperature range and can be switched back and forth between the two phases by heat excitation. In some structures, a heating element such as a resistive heating element is used to heat the phase change material to switch between the two phases. To switch between the two phases, the temperature needs to be increased. Very high temperatures and rapid cooling will result in an amorphous phase, while a smaller temperature increase or slower cooling will result in a crystalline phase. The different resistances can be sensed with a small current that does not cause a lot of heating.

[0049] The temperature increase can be obtained by applying a pulse to the heating element. The high current density caused by the pulse may lead to a local temperature increase. Depending on the duration and amplitude of the pulse, the resulting phase will differ. A larger pulse amplitude with a shorter duration, the so-called RESET pulse, can amorphize the cell, while a smaller pulse amplitude with a longer duration will bring the cell into its crystalline phase, the so-called SET pulse.

[0050] Rapid cooling or quenching is important for resetting the phase change material to the amorphous phase, as slow cooling leads to the crystalline phase. However, the temperature may not be evenly distributed along the heating element. For example, the temperature of the central portion of the heating element may be higher than its end portion (or end portion), and vice versa (depending on the circuit structure). A portion of the phase change material that overlaps the high temperature portion of the heating element will therefore be heated to a higher temperature and generally takes longer to quench. Longer quenching times may prevent portions of the phase change material from being reset to the amorphous phase. This quenching problem may cause the phase change material to stabilize in a state where portions of it in the crystalline phase are mixed with other portions in the amorphous phase, which impairs switching behavior and reduces circuit performance.

[0051] The present disclosure provides a PCM structure in which a phase change element includes individual segments of different sizes, thicknesses, volumes, and / or spacings. Multiple segments of the phase change element are distributed along the heating element and the temperature gradient on the heating element is fine-tuned to achieve a substantially uniform distribution. Therefore, multiple segments of the phase change element can be quenched at approximately the same rate and the quenching problem caused by the uneven temperature distribution along the heating element is mitigated.

[0052] Various aspects of the disclosure will now be described in more detail with reference to the accompanying drawings. Figure 1 1 is a flow chart of a method 100 for manufacturing a semiconductor device according to various aspects of the present disclosure. The method 100 is merely an example and is not intended to limit the present invention to what is explicitly described in the method 100. Additional steps may be provided before, during, and after the method 100, and some of the steps described may be moved, replaced, or removed for additional embodiments. For simplicity, not all steps are described in detail herein. Figures 2 to 24 Method 100 is described with reference to the cross-sectional view and top view of workpiece 200 shown in FIG. Because a PCM structure will be formed from workpiece 200, workpiece 200 may be referred to as PCM structure 200 as the context requires. Furthermore, throughout this disclosure, like reference numerals denote like features unless otherwise noted.

[0053] refer to Figure 1 and Figure 2, method 100 includes block 102, wherein a metal layer 206 is deposited on an etch stop layer (ESL) 204 including a dielectric material. ESL 204 may include silicon nitride, silicon oxycarbide, or silicon carbide. In the depicted embodiment, ESL 204 is disposed on an intermetal dielectric (IMD) layer 202. IMD layer 202 may include silicon oxide. In some embodiments, the IMD layer 202 may include a porous organosilicate thin film, such as SiOCH, tetraethylorthosilicate (TEOS) oxide, undoped silicate glass, doped silicon oxide, such as borophosphosilicate glass (BPSG), fused silica glass (FSG), phosphosilicate glass (PSG), fluorine-doped silicon dioxide, carbon-doped silicon dioxide, porous silicon dioxide, porous carbon-doped silicon dioxide, or a combination thereof. In at least some embodiments, the PCM structure manufactured using method 100 is disposed within an interconnect structure, which is considered a back-end-of-line (BEOL) structure. In these embodiments, the PCM structure may be used as a solid-state switch to switch between different communication frequencies. For example, the PCM structure may be used to switch between different fifth generation (5G) frequencies. Such an interconnect structure may include eight to nineteen metal layers. Each metal layer includes a plurality of contact vias extending vertically and a plurality of metal lines extending horizontally. The plurality of contact vias and the plurality of metal lines of each metal layer are embedded in an ESL similar to ESL 204 and an IMD layer similar to IMD layer 202. ESL 204 and IMD layer 202 can be formed on a semiconductor wafer. ESL 204, IMD layer 202 and / or semiconductor wafer can be regarded as a substrate.

[0054] The metal layer 206 may include tantalum (Ta), titanium (Ti), hafnium (Hf), ruthenium (Ru), platinum (Pt), iridium (Ir), molybdenum (Mo), tungsten (W), combinations thereof, or nitrides thereof. In one embodiment, the metal layer 206 is formed of tungsten (W). In this embodiment, tungsten has a low resistance to reduce energy consumption. The metal layer 206 may be deposited on the ESL 204 using chemical vapor deposition (CVD), physical vapor deposition (PVD), or other suitable techniques. Subsequently, the metal layer 206 will be patterned into a heating element.

[0055] refer to Figure 1 and Figure 3 , method 100 includes block 104, wherein an insulator layer 208 is deposited over metal layer 206. In some embodiments, insulator layer 208 includes silicon nitride, silicon oxycarbide, or silicon carbide. Insulator layer 208 may be deposited using CVD, PVD, or other suitable techniques. Insulator layer 208 has multiple uses. On the one hand, insulator layer 208 serves as a thermal barrier to prevent abrupt heating profiles that may destroy the phase change characteristics of the phase change element to be formed. For example, if a heating element is in direct contact with the phase change element, the heat generated by the heating element may permanently transform a portion of the phase change element into a crystalline phase. On the other hand, insulator layer 208 serves as a protective layer to prevent damage to the heating element during subsequent etching processes. In this regard, insulator layer 208 cannot be too thick, otherwise it will prevent the heating element from effectively heating the phase change material layer. Based on these considerations, insulator layer 208 may have a thickness between about 300 and about 1500. When insulator layer 208 is thinner than or thicker than It may not perform both functions well.

[0056] refer to Figure 1 and Figure 4, the method 100 includes a block 106, wherein the metal layer 206 and the insulator layer 208 are patterned to form a heating element 210 and an insulator 212, respectively. In some embodiments, the patterning at the block 106 includes a photolithography and etching process. In an example process, a mask layer 214 is deposited on the insulator layer 208. The mask layer 214 may include a photoresist. The mask layer 214 is then patterned using a photolithography technique to form a patterned mask layer 214. The patterned mask layer 214 is then used as an etching mask to etch the insulator layer 208 to form the insulator 212 and to etch the metal layer 206 to form the heating element 210. A suitable etching process may be an anisotropic dry etching process using an inert gas (e.g., Ar, He), a fluorine-containing gas (e.g., SF6, CHF3), a chlorine-containing gas (e.g., Cl2, BCl3), nitrogen (N2), oxygen (O2), other suitable gases and / or plasma, and / or combinations thereof. The heating element 210 is arranged directly below the insulator 212 when viewed in the direction Y. The mask layer 214 is subsequently removed, for example in an etching process or an ashing process.

[0057] refer to Figure 1 and Figure 5 , method 100 includes block 108, wherein a dielectric layer 216 is deposited on ESL 204 and on a plurality of sidewalls of heating element 210 and insulator 212. In some embodiments, dielectric layer 216 may include silicon oxide. In some embodiments, dielectric layer 216 may include a porous organic silicate film, such as SiOCH, tetraethyl orthosilicate (TEOS) oxide, undoped silicate glass, doped silicon oxide, such as borophosphosilicate glass (BPSG), fused silica glass (FSG), phosphosilicate glass (PSG), fluorine-doped silicon dioxide, carbon-doped silicon dioxide, porous silicon dioxide, porous carbon-doped silicon dioxide, or a combination thereof. In some embodiments, dielectric layer 216 has a composition similar to that of IMD layer 202. Dielectric layer 216 may be deposited using flowable chemical vapor deposition (FCVD), CVD, or spin coating. After depositing dielectric layer 216, dielectric layer 216 is planarized to expose a top surface of insulator 212. In other words, planarization is performed until the top surfaces of dielectric layer 216 and insulator 212 are coplanar, as shown in FIG. Figure 5 The planarization at block 108 may include a chemical mechanical polishing (CMP) process.

[0058] refer to Figure 1 and Figure 6, method 100 includes block 110, wherein a phase change material layer 218 is deposited on dielectric layer 216 and insulator 212. In some embodiments, phase change material layer 218 may include a chalcogenide material. Generally, a chalcogenide material refers to a compound including at least one sulfide ion from row VI of the periodic table. Chalcogenide materials may include sulfides, selenides, and tellurides. In some embodiments, phase change material layer 218 includes germanium (Ge), tellurium (Te), and antimony (Sb). In some cases, phase change material layer 218 includes germanium antimony tellurium (GeSbTe), silver indium antimony tellurium (AgInSbTe), or germanium tellurium (GeTe). In order to improve its performance, phase change material layer 218 may also be doped with various dopants, such as silicon (Si) or nitrogen (N). Phase change material layer 218 may be deposited using CVD, PVD, or other suitable techniques. In some embodiments, co-sputtering from multiple targets or sputtering from a composite target may be used to deposit the phase change material layer 218. In some cases, the composite target may have a composition similar to that of the phase change material layer 218.

[0059] refer to Figure 1 and Figure 7 , method 100 includes block 112, where phase change material layer 218 is patterned to form phase change element 220. In an example process, mask layer 222 is patterned to be used as an etch mask. Mask layer 222 may include photoresist. Mask layer 222 is then patterned using photolithography techniques to form patterned mask layer 222. Patterned mask layer 222 is then used as an etch mask to etch phase change material layer 218 to form phase change element 220. Figure 7 As shown, the phase change material layer 218 is patterned so that the phase change element 220 extends or spans over the insulator 212 and the heating element 210. In other words, along the vertical direction (i.e., direction Z), the phase change element 220 overlaps the insulator 212 and the heating element 210. The phase change element 220 is in direct contact with the insulator 212. The mask layer 222 is subsequently removed, for example, in an etching process or an ashing process.

[0060] Reference now Figure 8 , which is Figure 7 The top view of the PCM structure 200 is shown in FIG. Figure 7 The cross-sectional view shown in FIG. Figure 8 The structure of line AA shown in FIG. It should be noted that for the sake of simplicity of illustration, Figure 8 Does not include a graphic representation of each layer. For example, Figure 8The illustration of the mask layer 222, the insulator 212, the dielectric layer 216, the ESL 204, and the IMD layer 202 is omitted. Figure 8 In some embodiments shown, the heating element 210 extends longitudinally along direction Y. The heating element 210 is in a dumbbell shape, with two via pads on both sides and sandwiching a substantially uniform width W. h The through hole pad has a width W h Large expansion width W h During operation, current is conducted to the heating element 210 through the plurality of vias falling on the plurality of via pads to heat the heating element 210. The via pads may have a square, rectangular, circular, oval, or other suitable shape.

[0061] The phase change material layer 218 is patterned into a plurality of segments that collectively define the phase change element 220. In other words, the phase change element 220 includes a plurality of discrete segments. The plurality of segments of the phase change element 220 are arranged along the direction Y, and each segment overlaps a portion of the heating element 210. Figure 8 In the illustrated embodiment, the phase change element 220 includes six segments 220a to 220f, with substantially uniform width W0 and substantially uniform spacing S0 between adjacent two segments 220a to 220f, which is for illustrative purposes only and is not intended to limit the content beyond the specific description in the scope of the invention application. It is understood that any number of segments with different widths and / or different spacings can be formed in the phase change element 220 according to design requirements. Each of the segments 220a to 220f generally extends longitudinally along the direction X but has different lengths. In particular, in Figure 8 In the illustrated embodiment, segments 220d to 220f are mirror images of segments 220a to 220c relative to a line along direction X passing through the center point of the phase change element 220. Segments 220a and 220f located at the edge of the phase change element 220 have the longest length L1, segments 220c and 220d located at the center of the phase change element 220 have the shortest length L3, and other segments 220b and 220e of the phase change element 220 have intermediate lengths L2 (i.e., L1>L2>L3>W0). In the depicted embodiment, the shortest length L3 is greater than the width W of the heating element 210. h To ensure that the plurality of segments overlap with the heating element 210 in the direction X, the heat generated from the heating element 210 is effectively utilized. The reason for patterning the phase change element 220 into segments of different sizes will be referred to in detail. Fig.15 Further detailed explanation.

[0062] refer to Figure 1 and Fig. 9, method 100 includes block 114, wherein a dielectric layer 224 is deposited on dielectric layer 216 of phase change element 220 and a plurality of sidewalls of phase change element 220. In some embodiments, dielectric layer 224 may include silicon oxide. In some embodiments, dielectric layer 224 may include a porous organic silicate film, such as SiOCH, tetraethylorthosilicate (TEOS) oxide, undoped silicate glass, doped silicon oxide, such as borophosphosilicate glass (BPSG), fused silica glass (FSG), phosphosilicate glass (PSG), fluorine-doped silicon dioxide, carbon-doped silicon dioxide, porous silicon dioxide, porous carbon-doped silicon dioxide, or a combination thereof. In some embodiments, dielectric layer 224 has a composition similar to dielectric layer 216. In some embodiments, dielectric layer 224 has a composition different from dielectric layer 216. Dielectric layer 224 may be deposited using FCVD, CVD, or spin coating. After the dielectric layer 224 is deposited, the dielectric layer 224 is planarized to expose the top surface of the phase change element 220. In other words, the planarization is performed until the top surfaces of the dielectric layer 224 and the phase change element 220 are coplanar, such as Fig. 9 The planarization at block 114 may include a CMP process.

[0063] refer to Figure 1 and Fig.10 , method 100 includes block 116, where a metal layer 226 is deposited over dielectric layer 224 and phase change element 220. Metal layer 226 may include tantalum (Ta), titanium (Ti), hafnium (Hf), ruthenium (Ru), platinum (Pt), iridium (Ir), molybdenum (Mo), tungsten (W), combinations thereof, or nitrides thereof. Metal layer 226 may be deposited using CVD, PVD, or other suitable methods. In one embodiment, metal layer 226 is formed of tungsten (W).

[0064] refer to Figure 1 and Fig.11 , method 100 includes block 118, wherein the metal layer 226 is patterned into a plurality of electrodes 228. In some embodiments, patterning includes photolithography and etching processes. In an example process, a mask layer 230 is deposited over the metal layer 226. The mask layer 230 may include a photoresist. The mask layer 230 is then patterned using photolithography techniques to form a patterned mask layer 230 including a plurality of openings 232. The patterned mask layer 230 is then used as an etching mask to etch the metal layer 226 to form a plurality of electrodes 228 spaced apart from one another along a direction X. A suitable etching process may be an anisotropic dry etching process using an inert gas (e.g., Ar, He), a fluorine-containing gas (e.g., SF6, CHF3), a chlorine-containing gas (e.g., Cl2, BCl3), nitrogen (N2), oxygen (O2), other suitable gases and / or plasma, and / or combinations thereof. As Fig.11As shown, metal layer 226 is patterned so that multiple electrodes 228 extend or span a distance D0 over multiple edges of phase change element 220. In other words, along the vertical direction (i.e., direction Z), each electrode 228 overlaps phase change element 220. Phase change element 220 is in direct contact with multiple electrodes 228. Because multiple electrodes 228 of the present disclosure have sufficient conductivity for radio frequency (RF) applications, they may also be referred to as RF electrodes 228. Mask layer 230 is subsequently removed, for example, in an etching process or an ashing process.

[0065] Reference now Fig.12 , which is Fig.11 The top view of the PCM structure 200 is shown in FIG. Fig.11 The cross-sectional view shown in FIG. Fig.12 The structure of line AA shown in FIG. It should be noted that for the sake of simplicity of illustration, Fig.12 Does not include a graphic representation of each layer. For example, Fig.12 Illustration of the mask layer 230, the dielectric layer 224, the insulator 212, the dielectric layer 216, the ESL 204, and the IMD layer 202 is omitted. Fig.12 In some embodiments shown, each electrode 228 includes a common portion 234 and a plurality of extension arms 236 extending longitudinally from the common portion 234 along a direction X. The number of extension arms 236 is equal to the number of segments of the phase change element 220. In other words, each segment of the phase change element 220 has an edge that is in direct contact with a corresponding arm 236 of one of the plurality of electrodes 228, and another edge that is in direct contact with a corresponding arm 236 of another of the plurality of electrodes 228. Since the opposite edge portions of the plurality of segments of the phase change element 220 are covered by the plurality of extension arms 236 of the plurality of electrodes 228, Fig.12 The dashed box overlaps the segment to show the outline of the segment. Each extension arm 236 has a width W measured along the direction Y. e In some embodiments, the width W of the extension arm 236 is e The width W of the extension arm 236 may be equal to the width W0 of the corresponding segment. e The width W of the extension arm 236 may be greater than the width W0 of the corresponding segment to ensure good electrical contact between them. e The length of the extension arm 236 may be smaller than the width W0 of the corresponding segment to enlarge the gap between two adjacent extension arms 236 to reduce the parasitic capacitance between the plurality of extension arms 236. The extension arm 236 may overlap the corresponding segment by a substantially uniform distance D0. Depending on the length of the segment, the edge of the corresponding extension arm 236 may be away from the plurality of edges of the heating element 210 or overlap with the heating element 210. Fig.12In the illustrated embodiment, the plurality of extension arms 236 directly contacting segments 220a, 220b, 220e, and 220f have edges that are away from the edges of the heating element 210, while the plurality of extension arms 236 directly contacting segments 220c and 220d have edges that are above the heating element 210 along the direction Z. In other words, some of the extension arms 236 may overlap the heating element 210 in a top view. In some alternative embodiments, the edges of all the extension arms 236 are away from the heating element 210 along the direction X to avoid creating an overlapping area that may introduce additional parasitic capacitance.

[0066] refer to Figure 1 and Fig.13 , method 100 includes block 120, wherein a dielectric layer 238 is deposited over the plurality of electrodes 228 and the phase change element 220. In some embodiments, the dielectric layer 238 may include silicon oxide. In some embodiments, the dielectric layer 238 may include a porous organic silicate film, such as SiOCH, tetraethylorthosilicate (TEOS) oxide, undoped silicate glass, doped silicon oxide, such as borophosphosilicate glass (BPSG), fused silica glass (FSG), phosphosilicate glass (PSG), fluorine-doped silicon dioxide, carbon-doped silicon dioxide, porous silicon dioxide, porous carbon-doped silicon dioxide, or a combination thereof. In at least some embodiments of the present disclosure, the dielectric layer 216, the dielectric layer 224, and the dielectric layer 238 may have the same composition, such as silicon oxide. Alternatively, the dielectric layer 216, the dielectric layer 224, and the dielectric layer 238 may have different compositions from each other.

[0067] refer to Figure 1 and Fig.14A , the method 100 includes block 122, wherein a plurality of contact structures 240 are formed to couple to the plurality of electrodes 228. Fig.14A It is clearly shown in (but Fig.15 ), a plurality of contact structures 240 are also formed to couple to two via pads of the heating element 210. In the described embodiment, each contact structure 240 includes a via 242 and a metal line 244 disposed on the via 242. The via 242 and the metal line 244 may include aluminum (Al), copper (Cu), cobalt (Co), or nickel (Ni). In one embodiment, they both include copper (Cu). In the example process, the plurality of contact structures 240 are formed using a dual damascene process. Although not explicitly shown, the contact structure 240 may include a barrier layer to connect the dielectric layer 238. The barrier layer may include titanium nitride or tantalum nitride and serves to reduce electromigration.

[0068] Fig. 14B An alternative embodiment at the end of block 122 is shown. Fig. 14BThe embodiments described in Fig.14A The difference between the embodiments in FIG. 2 is that after forming the phase change element 220, the metal layer 226 is deposited as a capping layer and patterned to form a plurality of electrodes 228 without forming the dielectric layer 224. The plurality of electrodes 228 are in direct contact with the dielectric layer 216 and the plurality of sidewalls and the plurality of edge portions of the phase change element 220. The dielectric layer 238 covers the plurality of electrodes 228.

[0069] exist Fig.14A and Fig. 14B In the illustrated embodiment, the phase change element 220 is formed over the heating element 210 . Fig. 14C An alternative embodiment is shown in which the heating element 210 is formed above the phase change element 220. Fig. 14C In the alternative embodiment shown, a plurality of electrodes 228 are first formed on the ESL 204 and the dielectric layer 216 fills the openings therebetween, and the phase change element 220 and the insulator 212 are subsequently formed over the plurality of electrodes 228 and the dielectric layer 224 is deposited on the plurality of sidewalls thereof. Since the phase change element 220 and the insulator 212 can be patterned together, the phase change element 220 and the insulator 212 can have the same size, which is larger than the size of the subsequently formed heating element 210. The heating element 210 is then deposited on the insulator 212. The dielectric layer 238 covers the heating element 210.

[0070] Reference now Fig.15 , which is Fig.14A The top view of the PCM structure 200 is shown in FIG. Fig.14A The cross-sectional view shown in FIG. Fig.15 The structure of line AA shown in FIG. It should be noted that for the sake of simplicity of illustration, Fig.15 Does not include a graphic representation of each layer. For example, Fig.15 The dielectric layer 238, the dielectric layer 224, the insulator 212, the dielectric layer 216, the ESL 204, and the IMD layer 202 are omitted. Fig. 14B and Fig. 14C The cross-sectional view of the PCM structure 200 shown in the alternative embodiment is shown in the top view with Fig.15 2, but having a different stacking sequence of the plurality of electrodes 228, the phase change element 220, and the heating element 210. For the sake of brevity, such alternative top views are omitted.

[0071] exist Fig.15In some embodiments shown, due to the relatively large area provided by the common portion 234, multiple contact structures 240 fall on the common portion 234 of each electrode 228 in an effort to reduce contact resistance. The edge-to-edge span of the common portion 234 along the direction Y can be greater than the edge-to-edge span of the heating element 210 along the direction Y. In other words, the two through-hole pads of the heating element 210 are positioned within two opposite edges of the common portion 234 along the direction Y, which helps to reduce the footprint of the PCM structure 200. When more PCM structures 200 are needed, a smaller footprint is helpful. Alternatively, the multiple through-hole pads of the heating element 210 can extend beyond the opposite edges of the common portion 234 along the direction Y, which helps to expand the spacing between the multiple contact structures 240 falling on the heating element 210 and the neighbors falling on the multiple electrodes 228 in an effort to reduce the parasitic capacitance between them. Despite the larger footprint, the reduction of parasitic capacitance between the multiple contact structures 240 helps to improve the high-speed performance of the circuit.

[0072] Still reference Fig.15 , a temperature gradient map is overlaid next to the PCM structure 200. If a continuous phase change element 220 with uniform width overlaps the heating element 210, the curved dashed line shows the temperature gradient along the direction Y of the heating element 210. On the other hand, the solid line ripples represent the actual temperature gradient along the direction Y of the heating element 210 with the phase change element 220 having segments. The temperature gradient represented by the ripples is more uniform than the temperature gradient represented by the curved dashed line.

[0073] When current flows through the heating element 210 through the plurality of contact structures 240, the resistors in the heating element 210 generate Joule heat to heat the phase change element 220. At the same time, the metal in the plurality of contact structures 240, which is a good thermal conductor, also takes away heat from the plurality of end portions (i.e., the plurality of edge portions adjacent to the plurality of through-hole pads) of the heating element 210, so that the central portion of the heating element 210 exhibits a higher temperature than its plurality of end portions. In order to ensure that the temperature at the plurality of end portions of the heating element 210 is high enough during the RESET pulse, the temperature of the central portion of the heating element 210 may be dangerously high and exceed the reference temperature point T c . Exceeding the reference temperature point T c , the heated portion of the phase change element 220 will not be quenched quickly enough and may remain in the crystalline phase. Since the phase change element 220 also serves as a heat shield covering the heating element 210, by segmenting the phase change element 220 and making the plurality of segments (e.g., segment 220c and segment 220d) located above the central portion of the heating element 210 have smaller sizes (e.g., Fig.15The shortest length L3 in the heating element 210 is such that the heat gathered in the central portion of the heating element 210 is more easily dissipated into its surrounding environment. Therefore, the temperature at the central portion of the heating element 210 is also reduced to a temperature lower than the reference temperature point T c On the other hand, the segments (e.g., segments 220a and 220f) located near the multiple end portions of the heating element 210 have larger sizes (e.g., Fig.15 The maximum length L1 in the heating element 210 is 200 mm / s, which allows the heat accumulated at the multiple end portions of the heating element 210 to dissipate slowly and maintain above the reference temperature point T0, which ensures a sufficiently high temperature to melt the phase change material in the phase change element 220 during the RESET pulse. Therefore, the temperature gradient along the heating element 210 (and the multiple segments of the phase change element 220) along the direction Y becomes more uniformly distributed and is at the reference temperature points T0 and T0. c In some embodiments, the ratio of the maximum length L1 to the shortest length L3 (ie, L1 / L3) is in the range of about 1.2:1 to about 5:1, depending on design requirements.

[0074] Reference now Fig.16 , which is a top view of an alternative embodiment of a PCM structure 200 . Fig.16 The features of the alternative embodiment represented in Fig.15 One difference is that the phase change element 220 is segmented in a different manner such that multiple segments (e.g., segment 220c and segment 220d) above the central portion of the heating element 210 have a maximum dimension (e.g., as in Fig.16 The maximum length L1 in the heating element 210 and the plurality of segments near the plurality of end portions of the heating element 210 (eg, segments 220a and 220f) have a minimum size (eg, Fig.16 This arrangement is to compensate for different temperature gradients along the direction Y of the heating element 210. Fig.16 The curved dashed line in Fig.15 , indicating that the temperature at the end portions of the heating element 210 is higher. The reverse temperature gradient may be caused by other bulk metal structures covering the PCM structure 200 above or below. For example, a heat sink (not shown) for other functional circuits may be located just above the center portion of the heating element 210, such as formed in subsequent BEOL processes, and absorb heat from the center portion of the heating element 210.

[0075] Still reference Fig.16If a continuous phase change element 220 with uniform width overlaps the heating element 210, in order to ensure that the temperature of the central portion of the heating element 210 is high enough during the RESET pulse, the temperature of the multiple end portions of the heating element 210 may be dangerously high and exceed the reference temperature point T c Since the phase change element 220 also serves as a heat shield covering the heating element 210, by segmenting the phase change element 220 and making the plurality of segments (e.g., segment 220a and segment 220f) located above the plurality of end portions of the heating element 210 have smaller sizes (e.g., Fig.16 The shortest length L3 in the heating element 210 makes it easier for the heat gathered at the multiple end portions of the heating element 210 to dissipate into its surrounding environment. Therefore, the temperature at the multiple end portions of the heating element 210 is also reduced to a temperature lower than the reference temperature point T c On the other hand, a plurality of segments (eg, segment 220c and segment 220d) located above the central portion of the heating element 210 have larger sizes (eg, Fig.16 The maximum length L1 in the heating element 210 is reduced, which allows the heat accumulated in the central portion of the heating element 210 to dissipate more slowly and be maintained above the reference temperature point T0, which ensures a sufficiently high temperature to melt the phase change material in the phase change element 220 during the RESET pulse. Therefore, the temperature gradient along the heating element 210 (and the multiple segments of the phase change element 220) along the direction Y becomes more uniformly distributed and is at the reference temperature points T0 and T c For the boundary.

[0076] Reference now Fig.17 , which is a top view of an alternative embodiment of a PCM structure 200 . Fig.17 The features of the alternative embodiment represented in Fig.15 One difference is that the phase change element 220 is segmented in a different manner such that multiple segments have the same dimensions, such as substantially uniform length L0 and substantially uniform width W0, but have different edge-to-edge spacing (e.g., Fig.17, and the like. In the embodiment depicted, segments 220c and 220d have the largest spacing S1, segments 220a and 220b (as well as segments 220e and 220f) have the smallest spacing S3, and segments 220b and 220c (as well as segments 220d and 220e) have a medium spacing S2. This arrangement is intended to compensate for a temperature gradient along the direction Y of the heating element 210, where the highest temperature is at the central portion of the heating element 210. The larger spacing (e.g., spacing S1) between the multiple segments above the central portion of the heating element 210 allows the heat accumulated therein to dissipate more quickly into its surroundings. For different spacings, the temperature gradient along the direction Y of the heating element 210 (and the multiple segments of the phase change element 220) becomes more evenly distributed and is centered at reference temperature points T0 and T1. c In some embodiments, the ratio of the largest interval S1 to the smallest interval S3 (ie, S1 / S3 ) is in the range of about 1.2:1 to about 3:1, depending on design requirements.

[0077] Reference now Fig.18 , which is a top view of an alternative embodiment of a PCM structure 200 . Fig.18 The features of the alternative embodiment represented in Fig.16 One difference is that the phase change element 220 is segmented in a different manner such that multiple segments have the same dimensions, such as substantially uniform length L0 and substantially uniform width W0, but have different edge-to-edge spacing (e.g., Fig.18 , and the like. In the embodiment depicted, segments 220c and 220d have the smallest spacing S3, segments 220a and 220b (as well as segments 220e and 220f) have the largest spacing S1, and segments 220b and 220c (as well as segments 220d and 220e) have a medium spacing S2. This arrangement is intended to compensate for a temperature gradient along the direction Y of the heating element 210, where the highest temperatures are at the multiple end portions of the heating element 210. Larger spacings (e.g., spacings S1) between the multiple segments above the multiple end portions of the heating element 210 allow the heat accumulated therein to dissipate more quickly into its surroundings. For different spacings, the temperature gradient along the direction Y of the heating element 210 (and the multiple segments of the phase change element 220) becomes more evenly distributed and increases with reference temperature points T0 and T1. c For the boundary.

[0078] Reference now Fig.19 , which is a top view of an alternative embodiment of a PCM structure 200 . Fig.19 The features of the alternative embodiments shown in Fig.17One difference is that the phase change element 220 is segmented in a different manner such that multiple segments have the same dimensions, such as substantially uniform length L0 and substantially uniform center-to-center spacing, but different widths along direction Y (e.g., as shown in FIG. Fig.19 20a and 20f have the largest widths W1 to W3. In the depicted embodiment, segments 220a and 220f have the largest widths W1, segments 220c and 220d have the smallest widths W3, and segments 220b and 220e have intermediate widths W2. This arrangement is intended to compensate for temperature gradients along direction Y of the heating element 210, where the highest temperature is at the central portion of the heating element 210. The smallest widths (and correspondingly the largest edge-to-edge spacing) of the multiple segments above the central portion of the heating element 210 allow heat accumulated therein to dissipate more quickly into its surroundings. For different widths, the temperature gradient along the heating element 210 (and the multiple segments of the phase change element 220) along direction Y becomes more evenly distributed and is centered at reference temperature points T0 and T1. c In some embodiments, the ratio of the maximum width W1 to the minimum width W3 (ie, W1 / W3 ) is in the range of about 1.2:1 to about 3:1, depending on design requirements.

[0079] Reference now Fig. 20 , which is a top view of an alternative embodiment of a PCM structure 200 . Fig. 20 The features of the alternative embodiments shown in Fig.18 One difference is that the phase change element 220 is segmented in a different manner such that multiple segments have the same dimensions, such as substantially uniform length L0 and substantially uniform center-to-center spacing, but different widths along direction Y (e.g., as shown in FIG. Fig. 20 1 to 3). In the depicted embodiment, segments 220a and 220f have the smallest width W3, segments 220c and 220d have the largest width W1, and segments 220b and 220e have an intermediate width W2. This arrangement is intended to compensate for temperature gradients along direction Y of the heating element 210, where the highest temperatures are at the multiple end portions of the heating element 210. The smallest widths (and correspondingly the largest edge-to-edge spacing) of the multiple segments above the multiple end portions of the heating element 210 allow heat accumulated therein to dissipate more quickly into its surroundings. For different widths, the temperature gradient along the heating element 210 (and the multiple segments of the phase change element 220) along direction Y becomes more evenly distributed and is centered at reference temperature points T0 and T1. c For the boundary.

[0080] Reference now Fig.21, which is a top view of an alternative embodiment of a PCM structure 200 . Fig.21 The features of the alternative embodiments shown in Fig.17 One difference is that the phase change element 220 is segmented in a different manner such that the multiple segments have the same dimensions, such as substantially uniform length L0, substantially uniform width W0, and substantially uniform edge-to-edge spacing S0, but different thicknesses along direction Z (e.g., as Fig.21 The different thicknesses may be achieved by additional etching processes to further thin certain segments of the phase change element 220. In the described embodiment, segments 220a and 220f have the largest thickness H1, segments 220c and 220d have the smallest thickness H3, and segments 220b and 220e have a medium thickness H2. In other words, segments 220a and 220f have the largest volume, segments 220c and 220d have the smallest volume, and segments 220b and 220e have a medium volume. This arrangement is to compensate for the temperature gradient along the direction Y of the heating element 210, where the highest temperature is in the central portion of the heating element 210. The minimum volume of the multiple segments above the central portion of the heating element 210 allows the heat accumulated therein to dissipate more quickly into its surrounding environment. For different thicknesses, the temperature gradient along the direction Y of the heating element 210 (and the multiple segments of the phase change element 220) becomes more evenly distributed and is at reference temperature points T0 and T c In some embodiments, the ratio of the maximum thickness H1 to the minimum thickness H3 (ie, H1 / H3 ) is in the range of about 1.2:1 to about 3:1, depending on design requirements.

[0081] Reference now Fig. 22 , which is a top view of another alternative embodiment of a PCM structure 200 . Fig. 22 The features of the alternative embodiment represented in Fig.18 One difference is that the phase change element 220 is segmented in a different manner such that multiple segments have the same dimensions, such as a substantially uniform length L0, a substantially uniform width W0, and a substantially uniform edge-to-edge spacing S0, but different thicknesses along direction Z (e.g., Fig. 2220a and 20f have a minimum volume, segments 220c and 20d have a maximum volume, and segments 220b and 20e have a medium volume. This arrangement is intended to compensate for a temperature gradient along the direction Y of the heating element 210, where the highest temperature is at the multiple end portions of the heating element 210. The minimum volume of the multiple segments above the multiple end portions of the heating element 210 allows the heat accumulated therein to dissipate more quickly into its surrounding environment. For different thicknesses, the temperature gradient along the direction Y of the heating element 210 (and the multiple segments of the phase change element 220) becomes more evenly distributed and is centered at the reference temperature points T0 and T c For the boundary.

[0082] exist Figures 15 to 22 In the above-described embodiments shown, the different lengths, widths, edge-to-edge spacings, and thicknesses of the multiple segments of the phase change element 220 can be applied independently or in combination. For example, the multiple segments of the phase change element 220 can have different lengths and different thicknesses at the same time to more effectively achieve temperature gradient regulation. In another example, the multiple segments of the phase change element 220 can have different lengths and different widths at the same time. In yet another example, the multiple segments of the phase change element 220 can have different lengths, different widths, different edge-to-edge spacings, and different thicknesses at the same time.

[0083] Even though the phase change element 220 may have the same number of segments, the number of segments translates into different edge-to-edge spacings and the temperature gradient along the heating element 210 may still be adjusted. If the temperature gradient along the heating element 210 is too high, the phase change element 220 may use fewer segments to dissipate heat faster with a larger edge-to-edge spacing. If the temperature gradient along the heating element 210 is too low, the phase change element 220 may use more segments to accumulate heat with a smaller edge-to-edge spacing. The semiconductor device may include both structures. Fig.23 An embodiment is depicted in which a first PCM structure 200-1 includes a phase change element 220 having the same but fewer segments and a greater edge-to-edge spacing than a second PCM structure 200-2 phase change element 220. This may be due to the heating element 210 in the first PCM structure 200-1 having a temperature gradient that is too high, and the heating element 210 in the second PCM structure 200-2 having a temperature gradient that is too low.

[0084] Since multiple segments of phase change element 220 may vary in size, volume, and / or spacing to adjust the temperature gradient along heating element 210, such adjustments may also be used to adjust the ON and OFF sequence of multiple RF paths through the multiple segments. Fig.24 An embodiment is depicted in which a plurality of extension arms 236 on one side of the phase change element 220 connect a plurality of segments of the phase change element 220 to a first port PORT 1, while a plurality of extension arms 236 on the other side of the phase change element 220 fan out to connect each segment to a separate port. Specifically, segment 220a is connected to a second port PORT 2, segment 220b is connected to a third port PORT 3, segments 220c and 220d are connected to a fourth port PORT 4, segment 220e is connected to another second port PORT 2, and segment 220f is connected to another third port PORT 3. The segments 220a to 220f may be changed in such a way that a temperature gradient causes a plurality of ports to be turned on in a sequence from the second port PORT 2 to the third port PORT 3 to the fourth port PORT 4. Alternatively, the segments 220a to 220f may be changed in such a way that a temperature gradient causes a plurality of ports to be turned on in a sequence from the fourth port PORT 4 to the third port PORT 3 to the second port PORT 2. Due to symmetry, the two second ports PORT 2 are ON and OFF at the same time. Due to symmetry, the two third ports PORT 3 are both ON and OFF at the same time. This configuration of sequentially turning on the RF paths may be particularly useful for different RF components to receive RF signals from the first port PORT 1 at different time stamps.

[0085] In one exemplary aspect, the present disclosure relates to a semiconductor structure. The semiconductor structure includes a first electrode and a second electrode disposed on a substrate, a heating element disposed on the substrate, a phase change material layer disposed on the substrate, and an insulator disposed vertically between the heating element and the phase change material layer. The phase change material layer includes at least a first segment and a second segment separated from the first segment; each of the first and second segments overlaps with the heating element in a top view; each of the first and second segments is electrically connected to the first and second electrodes. In some embodiments, the first and second segments have different sizes in a top view. In some embodiments, the first and second segments have the same width but different lengths. In some embodiments, the first and second segments have the same length but different widths. In some embodiments, the first and second segments have different volumes. In some embodiments, the first and second segments have different thicknesses. In some embodiments, the phase change material layer further includes a third segment separated from the first and second segments and overlapping with the heating element in a top view, the first, second and third segments are sequentially disposed along the longitudinal direction of the heating element, and the edge-to-edge spacing between the first and second segments is different from the edge-to-edge spacing between the second and third segments. In some embodiments, each of the first and second electrodes includes at least a first extension arm in contact with the first segment and a second extension arm in contact with the second segment, and a common portion connecting the first and second extension arms. In some embodiments, the width of the first extension arm is equal to the width of the first segment, and the width of the second extension arm is equal to the width of the second segment. In some embodiments, the heating element is vertically disposed between the substrate and the phase change material layer. In some embodiments, the phase change material layer is vertically disposed between the substrate and the heating element.

[0086] In another exemplary aspect, the present disclosure relates to a semiconductor structure. The semiconductor structure includes a first electrode and a second electrode spaced apart along a first direction, a phase change material layer spanning and contacting the first electrode and the second electrode, the phase change material layer including a plurality of segments spaced apart along a second direction perpendicular to the first direction, a metal feature overlapping the phase change material layer, the metal feature extending longitudinally along the second direction, and an insulator vertically disposed between the phase change material layer and the metal feature. In some embodiments, each of the plurality of segments extends longitudinally along the first direction. In some embodiments, the plurality of lengths of the plurality of segments measured along the first direction are different. In some embodiments, the plurality of widths of the plurality of segments measured along the second direction are different. In some embodiments, the plurality of intervals of the plurality of segments between adjacent two of the plurality of segments are different. In some embodiments, the semiconductor structure further includes a third electrode spaced apart from the first electrode and the second electrode, each of the plurality of segments contacts the first electrode, a first portion of the plurality of segments contacts the second electrode, and a second portion of the plurality of segments contacts the third electrode.

[0087] In yet another exemplary aspect, the present disclosure relates to a method. The method includes depositing a first metal layer on a substrate, patterning the first metal layer to form a heating element, depositing a phase change material layer on the substrate, patterning the phase change material layer so that the patterned phase change material layer has a plurality of segments overlapping the heating element, the plurality of segments are spaced apart from each other, depositing a second metal layer on the substrate, and patterning the second metal layer to form a first electrode and a second electrode, the patterned phase change material layer being in contact with the first and second electrodes. In some embodiments, the heating element extends longitudinally in a first direction, and the plurality of segments are spaced apart from each other in the first direction. In some embodiments, the plurality of segments have different lengths, widths, thicknesses, volumes, or spacings.

[0088] The features of several embodiments are summarized above so that those skilled in the art can better understand the various aspects of the present invention. Those skilled in the art should understand that they can easily use the present invention as a basis for designing or modifying other processes and structures to implement the same purposes and / or achieve the same advantages as the embodiments described herein. Those skilled in the art should also recognize that these equivalent constructions do not depart from the spirit and scope of the present invention, and they can make various changes, substitutions and modifications herein without departing from the spirit and scope of the present invention.

Claims

1. A semiconductor structure, characterized in that: include: The first electrode and the second electrode are disposed on the substrate; A heating element is disposed on the substrate; A phase change material layer is disposed on the substrate; as well as An insulator is vertically disposed between the heating element and the phase change material layer, The phase change material layer includes at least a first segment and a second segment separated from the first segment, each of the first segment and the second segment overlaps the heating element in a top view, and each of the first segment and the second segment is electrically connected to the first electrode and the second electrode.

2. The semiconductor structure according to claim 1, characterized in that: The first segment and the second segment have different sizes in the top view.

3. The semiconductor structure according to claim 1, characterized in that: The first segment and the second segment have different volumes.

4. The semiconductor structure according to claim 1, characterized in that: The first segment and the second segment have different thicknesses.

5. The semiconductor structure according to claim 1, characterized in that: The phase change material layer also includes a third segment separated from the first segment and the second segment and overlapping the heating element in the top view, the first segment, the second segment and the third segment are arranged in sequence along the longitudinal direction of the heating element, and the edge-to-edge spacing between the first segment and the second segment is different from the edge-to-edge spacing between the second segment and the third segment.

6. The semiconductor structure according to claim 1, characterized in that Each of the first electrode and the second electrode includes at least a first extending arm in contact with the first segment, a second extending arm in contact with the second segment, and a common portion connecting the first extending arm and the second extending arm.

7. A semiconductor structure, characterized in that: include: The first electrode is spaced apart from the second electrode along a first direction; a phase-change material layer spanning and contacting the first electrode and the second electrode, wherein the phase-change material layer includes a plurality of segments spaced apart along a second direction perpendicular to the first direction; a metal feature overlapping the phase change material layer, wherein the metal feature extends longitudinally along the second direction; as well as An insulator is vertically disposed between the phase change material layer and the metal feature.

8. The semiconductor structure according to claim 7, characterized in that: Each of the plurality of segments extends longitudinally along the first direction.

9. The semiconductor structure according to claim 7, characterized in that: Lengths of the segments measured along the first direction are different.

10. The semiconductor structure according to claim 7, characterized in that: Widths of the segments measured along the second direction are different.

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