Micro-electro-mechanical system device

Abstract

The utility model provides a micro electro mechanical system device. The micro electro mechanical system device comprises a top metal layer, a first adhesion layer, a main dielectric layer, a second adhesion layer, a protective material, a bottom plate layer and an annular through hole, and the first adhesion layer is positioned on the top metal layer. The main dielectric layer is located on the first adhesion layer, and the main dielectric layer comprises a groove. The second adhesive layer is located on the main dielectric layer, and the second adhesive layer comprises a groove opening located above the groove and an annular opening. And a protective material covering a side of the second adhesive layer in the annular opening. And the bottom plate layer covers the second adhesion layer and fills the groove. And an annular through hole which passes through the bottom plate layer and reaches the main dielectric layer downwards.

Description

Technical Field

[0001] This utility model relates to an integrated circuit, and more particularly to a micro-electro-mechanical system (MEMS) device. Background Technology

[0002] Microelectromechanical systems (MEMS) are a technology that employs miniature mechanical and electromechanical components (e.g., devices or structures) on a wafer substrate. Utilizing microfabrication techniques, MEMS devices range from relatively simple structures with no moving components to complex electromechanical systems utilizing various moving components under the control of integrated microelectronic controllers. Devices or structures that can be used in MEMS include microsensors, microactuators, microelectronic devices, and microstructures. MEMS devices can be used in a wide variety of applications, including, but not limited to, motion sensors, pressure sensors, inertial sensors, micro-fluidic devices (e.g., valve, pump, nozzle controllers), optical devices, and imaging devices (e.g., micromachined ultrasonic transducers (MUTs), capacitive MUTs (CMUTs), and similar devices).

[0003] MEMS structures can be fabricated using photolithography patterning, which uses ultraviolet light to transfer a desired mask pattern onto a photoresist layer on a semiconductor wafer. The pattern can then be transferred to a layer beneath the photoresist using an etching process. This process can be repeated multiple times using different patterns to build different layers on the wafer substrate and fabricate useful devices. Utility Model Content

[0004] According to an embodiment of the utility model, a microelectromechanical system (MEMS) device includes a top metal layer, a first adhesive layer, a main dielectric layer, a second adhesive layer, a protective material, a base plate layer, and an annular through-hole. The first adhesive layer is located above the top metal layer. The main dielectric layer is located on the first adhesive layer and includes a groove. The second adhesive layer is located on the main dielectric layer and includes a groove opening and an annular opening located above the groove. The protective material covers the side of the second adhesive layer in the annular opening. The base plate layer covers the second adhesive layer and fills the groove. The annular through-hole passes through the base plate layer and extends downward to the main dielectric layer.

[0005] To make the above-mentioned features and advantages of this utility model more apparent and understandable, specific embodiments are described below, and detailed descriptions are provided in conjunction with the accompanying drawings. Attached Figure Description

[0006] The various aspects of this utility model will be best understood when the following detailed description is read in conjunction with the accompanying drawings. It should be noted that, according to standard practice in the industry, the various features are not drawn to scale. In fact, for clarity of explanation, the dimensions of the various features may be arbitrarily increased or decreased.

[0007] Figures 1A to 1C These are various views of a first exemplary embodiment of a MEMS structure according to some embodiments of the present invention. Here, a chemical stop structure is present in the second adhesive layer and the substrate also forms a chemical stop structure. Figure 1A Is it through Figure 1B The Y-axis sectional view of line AA shown. Figure 1B It is a top-down plan view. Figure 1C Is it through Figure 1B The Y-axis sectional view of line CC is shown, along with additional information.

[0008] Figure 1D Is it through Figure 1B The Y-axis cross-sectional view along line AA shows a second exemplary embodiment of a MEMS structure according to some embodiments of the present invention. Here, a chemical stopping structure is present in the second adhesive layer.

[0009] Figure 1E Is it through Figure 1B The Y-axis cross-sectional view shown by line AA illustrates a third exemplary embodiment of a MEMS structure according to some embodiments of the present invention. Here, the substrate forms a chemical stop structure.

[0010] Figure 2 This is a flowchart illustrating a first method for forming a substrate of a MEMS device including one or more chemical stop structures, according to some embodiments. Figures 3 to 9 The various steps of this method are shown.

[0011] Figure 3 Is it through Figure 1B The Y-axis cross-sectional view shown by line AA shows a substrate with an intermetallic dielectric layer surrounding an intermetallic layer and a top metal layer.

[0012] Figure 4 Is it through Figure 1B The Y-axis cross-sectional view shown by line AA shows the substrate after the formation of the first adhesive layer, the main dielectric layer and the second adhesive layer.

[0013] Figure 5A Is it through Figure 1B The Y-axis cross-sectional view shown by line AA shows the substrate after the second adhesive layer has been patterned to expose the groove openings and annular openings.

[0014] Figure 5B yes Figure 5A Plan view of the substrate shown.

[0015] Figure 6 Is it through Figure 1B The Y-axis cross-sectional view shown by line AA illustrates the substrate after partial etching of the main dielectric layer has created a groove above the top metal layer.

[0016] Figure 7A Is it through Figure 1B The Y-axis cross-sectional view shown by line AA shows the substrate after the grooves have been etched down to the first adhesive layer to form a step.

[0017] Figure 7B yes Figure 7A Plan view of the substrate shown.

[0018] Figure 8A This is a plan view of the substrate after it has been etched down through the groove to the top metal layer and after a protective material has been deposited in the annular opening of the second adhesive layer.

[0019] Figure 8B It is through the line BB. Figure 8A The first Y-axis cross-sectional view of the substrate shown, with line BB corresponding to Figure 1B Line AA is shown.

[0020] Figure 8C It passes through line CC. Figure 8A The second Y-axis cross-sectional view of the substrate shown.

[0021] Figure 9 Is it through Figure 8A The Y-axis cross-sectional view of line BB shows the substrate after the base plate material has been deposited on the second adhesive layer and deposited into the groove.

[0022] Figure 10 This is a flowchart illustrating a second method for forming a substrate of a MEMS device including one or more chemical stop structures, according to some embodiments. Figures 11 to 14 The various steps of this method are shown.

[0023] Figure 11 Is it through Figure 1B The Y-axis cross-sectional view shown by line AA illustrates the substrate after partial etching of the main dielectric layer has created a groove above the top metal layer.

[0024] Figure 12 Is it through Figure 1BThe Y-axis cross-sectional view shown by line AA illustrates the substrate after the second adhesive layer has been deposited and patterned to expose the groove openings and annular openings, and after etching down through the groove openings to the first adhesive layer. The second adhesive layer is also present on the steps.

[0025] Figure 13 Is it through Figure 1B The Y-axis cross-sectional view shown by line AA shows the substrate after the deposition of protective material in the annular opening of the second adhesive layer, the deposition of substrate material, and the formation of annular vias through the protective material to the main dielectric layer.

[0026] Figure 14 This is a flowchart illustrating a third method for forming a substrate of a MEMS device including a chemically stopped structure, according to some embodiments. Figures 15 to 16 The various steps of this method are shown.

[0027] Figure 15 Is it through Figure 1B The Y-axis cross-sectional view shown by line AA illustrates the substrate after the grooves in the main dielectric layer are etched down to the first adhesive layer and subsequently a second adhesive layer is deposited.

[0028] Figure 16 Is it through Figure 1B The Y-axis cross-sectional view shown by line AA illustrates the substrate after an annular opening is formed in the second adhesive layer, a protective material is deposited in the annular opening, and a base plate material is deposited. Detailed Implementation

[0029] The following disclosure provides numerous different embodiments or instances for implementing various features of the provided object. Specific examples of components and arrangements are described below to simplify the present invention. Of course, these are merely examples and are not intended to be limiting. For example, the following description of a first feature formed on or on a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, thereby potentially preventing direct contact between the first and second features. Furthermore, reference numerals and / or letters may be reused in various instances of the present invention. Such reuse is for the purpose of brevity and clarity and does not in itself indicate a relationship between the various embodiments and / or configurations discussed.

[0030] Furthermore, for ease of explanation, spatially relative terms such as "beneath," "below," "lower," "above," and "upper" may be used herein to describe the relationship between one component or feature shown in the figures and another component or feature. In addition to the orientations shown in the figures, these spatially relative terms are also intended to encompass different orientations of the device during use or operation. The device may have other orientations (rotated 90 degrees or in other orientations), and the spatially relative descriptive terms used herein will be interpreted accordingly.

[0031] The numerical values ​​in the specification and claims of this application should be understood to include the same numerical values ​​when reduced to the same number of significant figures, as well as numerical values ​​that differ from the stated values ​​by less than the experimental errors of the conventional measurement techniques used to determine the values ​​as described in this application. All ranges disclosed herein include the stated endpoints.

[0032] The term "about" can be used to include any numerical value that can vary without altering its underlying functionality. When used in conjunction with a range, "about" also indicates a range defined by the absolute values ​​of its two endpoints; for example, "about 2 to about 4" also indicates a range "from 2 to 4". The term "about" can refer to positive or negative 10% of the indicated number.

[0033] The term "Gundam X" is used in this invention to indicate the amount of a given material. This term should be interpreted as requiring the given material to be present in an amount greater than zero, or in other words, excluding the value of zero.

[0034] This invention relates to a structure composed of different layers. When the term "on or upon" is used to refer to two different layers (including a substrate), it indicates only that one layer is on or upon the other. These terms do not require that the two layers be in direct contact with each other and allow other layers to be located between the two layers. For example, all layers of the structure may be considered "on" the substrate even if they are not all in direct contact with it. The term "direct" can be used to indicate that two layers are in direct contact with each other, and there is no layer between the two layers. Furthermore, when referring to performing process steps on or on a substrate, it is context-dependent and should be interpreted as performing such steps on any layers that may be present on the substrate.

[0035] The term "ring" is used in this document to refer to a structure that forms a ring. The ring can be of any shape, such as a circle, a square, a triangle, etc.

[0036] Various embodiments of this invention relate to microelectromechanical systems (MEMS) structures that can be used in various devices. In some MEMS structures, the adhesive layers may be exposed to etching chemicals originally intended to etch other layers, but these etching chemicals can also erode the material of the adhesive layers. This can lead to the peeling of layers initially bonded together through the adhesive layers (e.g., a base plate for a pillar with a high aspect ratio). Alternatively, other layers can be peeled if a path exists downwards from the exposed adhesive layer to other adhesive layers within the MEMS structure. Various embodiments of this invention disclose chemical stop structures for protecting the adhesive layers present within the MEMS structure.

[0037] Figures 1A to 1C These are various views of a first exemplary embodiment of a MEMS structure 101 according to some embodiments of the present invention. Figure 1A Is it through Figure 1B The Y-axis sectional view of line AA shown. Figure 1B It is a top-down plan view. Figure 1C Is it through Figure 1B The Y-axis sectional view of line CC shown.

[0038] First refer to Figure 1A The MEMS structure is formed on a substrate 105. An intermetallic layer 110 is present on the substrate. A top metal layer 120 is present on the intermetallic layer 110, or in other words, the intermetallic layer is located below the top metal layer. An intermetallic dielectric (IMD) layer 130 surrounds the intermetallic layer 110 and the top metal layer 120. In other words, the intermetallic layer 110 and the top metal layer 120 exist within the IMD layer 130. The upper surface 122 of the top metal layer 120 is exposed, or in other words, not covered by the IMD layer 130.

[0039] A first adhesive layer 140 is formed on the IMD layer 130. A main dielectric layer 150 is formed on the first adhesive layer 140. The upper surface 152 of the main dielectric layer 150 includes a groove 160, which is defined to include a step 170, or in other words, the step 170 is a horizontal surface located within the main dielectric layer below the upper surface 152 and above the first adhesive layer 140. An upper rise 176 located at one end of the step extends to the upper surface 152. A lower rise 178 located at the opposite end of the step extends to the first adhesive layer 140. The groove 160 itself can be considered as being formed by the upper groove portion 162 and the lower groove portion 166. The main dielectric layer 150 also serves as a protective layer for the first adhesive layer 140 and the IMD layer 130.

[0040] Continue to refer to Figure 1AA second adhesive layer 180 is present on the main dielectric layer 150. In this embodiment, the second adhesive layer 180 is located on the upper surface 152 of the main dielectric layer and is not present in the groove 160. In other words, the second adhesive layer includes a groove opening 182 present on the top metal layer 120. The base plate layer 190 covers the second adhesive layer 180 and also fills the groove 160.

[0041] An annular via 200 is present around the recess 160. The annular via extends downward through the base plate layer 190 and the second adhesive layer 180 to the main dielectric layer 150. There is no material in the annular via 200, or in other words, the annular via is empty. The annular via exists within an annular opening 184 in the second adhesive layer 180, and a protective material 210 covers the side of the second adhesive layer in the annular opening. The annular via also divides the base plate layer 190 into a peripheral portion 192 and a central portion 194 located on opposite sides of the annular via. The annular via can also be described as passing through the protective material 210. The protective material 210 separates the annular via 200 from the second adhesive layer 180. It should be noted that although referred to as a layer, the central portion 194 of the base plate layer may extend upward, for example, to form a pillar. The central portion 194 of the base plate layer is electrically insulated through the annular via 200.

[0042] As can be seen here, there are two different chemical stop structures. The first chemical stop structure is the protective material 210, which prevents etching chemicals from contacting the second adhesive layer 180. The second chemical stop structure is the base layer 190, which separates the second adhesive layer 180 from the first adhesive layer 140 and blocks any chemical etching path to the first adhesive layer.

[0043] Now refer to Figure 1B The plan view indicates the peripheral portion 192 and the central portion 194 of the base layer. The main dielectric layer 150 is visible through the annular via. Also note the line AA ( Figure 1A The sectional view is taken from line AA, which is off-center from the center line CC.

[0044] The first adhesive layer 140 itself can be made of a conductive metal, which allows current to flow from the top metal layer to the bottom layer. Alternatively, in... Figure 1C In some embodiments shown, a perforation 220 extending from the groove through the first adhesive layer 140 may also be present, so that the base plate layer 190 can contact the top metal layer 120. This optional perforation (when present) may be filled with the base plate material used to form the base plate layer. This figure illustrates various dimensions of individual components of the MEMS structure.

[0045] The intermetallic layer 110 has a width 115 and a depth 117. In a particular embodiment, the width 115 is from about 0.5 micrometers (μm) to about 10 micrometers. In a particular embodiment, the depth 117 is from about 0.5 micrometers to about 5 micrometers. Combinations of width and depth are also conceivable. Other ranges and values ​​of each of these properties are also within the scope of this invention.

[0046] The top metal layer 120 has a width 125 and a depth 127. The width 125 of the top metal layer is generally smaller than the width 115 of the intermetallic layer 110. In a particular embodiment, the width 125 is from about 0.5 micrometers to about 10 micrometers. In a particular embodiment, the depth 127 is from about 0.5 micrometers to about 5 micrometers. Combinations of width and depth are also conceivable. Other ranges and values ​​of each of these properties are also within the scope of this invention.

[0047] IMD layer 130 has a depth of 137. In a particular embodiment, the depth 137 is from about 0.5 micrometers to about 15 micrometers. Other ranges and values ​​are also within the scope of this invention.

[0048] The first adhesive layer 140 has a depth of 147. In a particular embodiment, the depth 147 is up to about 10 micrometers. In some embodiments, the depth is at least 0.1 micrometers. Other ranges and values ​​are also within the scope of this invention.

[0049] The main dielectric layer 150 has a depth of 157. In a particular embodiment, the depth 157 is from about 0.2 micrometers to about 200 micrometers. Other ranges and values ​​are also within the scope of this invention.

[0050] The bottom of the base plate has a width of 195. In a particular embodiment, the width 195 is from about 0.5 micrometers to about 100 micrometers. Other ranges and values ​​are also within the scope of this invention. The width of the lower recessed portion 166 is also equal to the width 195. The width 125 of the top metal layer is less than or equal to the width 195 of the bottom of the base plate.

[0051] The lower recessed portion 166 and the lower raised portion 178 each have the same depth 169. In a particular embodiment, the depth 169 is from about 0.1 micrometers to about 100 micrometers. Other ranges and values ​​are also within the scope of this invention.

[0052] When present, the perforation 220 has a width of 225. The width of the perforation 225 is less than or equal to the width 195 of the bottom of the base plate. In a particular embodiment, the width 225 is up to about 100 micrometers when present. Other ranges and values ​​are also within the scope of this invention.

[0053] The upper recessed portion 162 has a width of 163. In a particular embodiment, the width 163 is from about 0.5 micrometers to about 300 micrometers. Other ranges and values ​​are also within the scope of this invention. The width 163 of the upper recessed portion 162 is greater than the width 195 of the bottom of the base plate. The width 163 of the upper recessed portion 162 is also greater than the width 225 of the perforation.

[0054] The upper recessed portion 162 and the upper raised portion 176 each have the same depth 165. In a particular embodiment, the depth 165 is from about 0.1 micrometers to about 100 micrometers. Other ranges and values ​​are also within the scope of this invention.

[0055] Step 170 has a width of 175. In a particular embodiment, the width 175 is up to about 100 micrometers. In some embodiments, the width is at least 0.1 micrometers. Combinations are conceivable. Other ranges and values ​​are also within the scope of this invention.

[0056] The second adhesive layer 180 has a depth of 187. In a particular embodiment, the depth 187 is from about 0.1 micrometers to about 10 micrometers. Other ranges and values ​​are also within the scope of this invention. The depth of the protective material is the same as the depth of the second adhesive layer.

[0057] The protective material 210 located on each side of the annular through-hole 200 has a width 215. In a particular embodiment, the width 215 is up to about 10 micrometers. In some embodiments, the width is at least 0.1 micrometers. Other ranges and values ​​are also within the scope of this invention.

[0058] The portion 188 of the second adhesive layer 180 located between the protective material 210 and the groove 160 has a width 189. In a particular embodiment, the width 189 is up to about 100 micrometers. In some embodiments, the width is at least 0.1 micrometers. Other ranges and values ​​are also within the scope of this invention.

[0059] The annular via 200 has a width of 205 and a depth of 207. The width is measured at the bottom of the annular via adjacent to the main dielectric layer. In a particular embodiment, the width 205 is from about 0.1 micrometers to about 100 micrometers. In a particular embodiment, the depth 207 is from about 0.2 micrometers to about 200 micrometers. Combinations of width and depth are also conceivable. Other ranges and values ​​of each of these properties are also within the scope of this invention.

[0060] The annular via has a taper angle 208. In a particular embodiment, the taper angle 208 is from about 30° to about 135°. Other ranges and values ​​are also within the scope of this invention. The protective material also has a taper angle 218. In a particular embodiment, the taper angle 218 is from about 30° to about 135°. Other ranges and values ​​are also within the scope of this invention. In a more specific embodiment, the taper angle 208 of the annular via is greater than the taper angle 218 of the protective material. In this regard, a taper angle greater than 90° will indicate that the width at the bottom of the annular via / protective material is greater than the width at the top of the annular via / protective material. For example, when forming an annular via / annular opening, this shape can be obtained by performing both dry etching and wet etching.

[0061] Figure 1D This is a Y-axis cross-sectional view showing a second exemplary embodiment of the MEMS structure 102 according to some embodiments of the present invention. Here, there is no protective material in the annular opening 184 of the second adhesive layer. However, there is a step 170 in the main dielectric layer 150, and the substrate forms a chemical stop structure. The first adhesive layer 140 and the second adhesive layer 180 are not in contact with each other.

[0062] Figure 1E This is a Y-axis cross-sectional view showing a third exemplary embodiment of the MEMS structure 103 according to some embodiments of the present invention. In this embodiment, the protective material 210 is a chemical stop structure that prevents etching chemicals from contacting the second adhesive layer 180. Therefore, as shown here, there are no steps in the main dielectric layer 150, and the second adhesive layer 180 can contact the first adhesive layer 140. In addition, the annular via 200 is shown as having a rectangular shape, rather than a trapezoidal shape that narrows downward toward the main dielectric layer.

[0063] Figure 2 This is a flowchart illustrating a first method 301 according to some embodiments. The first method 301 is used to form a substrate for a MEMS device and to form one or more chemical stop structures to reduce etching of the adhesion layer. Some steps of the method are also described below. Figures 3 to 9 The figures are shown below. These figures provide different views for better understanding. Although the method steps are discussed below in terms of forming a single base plate, this discussion should also be interpreted broadly as applicable to forming multiple base plates simultaneously.

[0064] First refer to Figure 3 ,exist Figure 2 In step 305, an intermetallic layer 110 is formed on the substrate 105. Then, in Figure 2 In step 310, a top metal layer 120 is formed on the intermetallic layer 110. Then, in Figure 2 In step 315, an IMD layer 130 is formed around the intermetallic layer 110 and the top metal layer 120. The resulting structure... Figure 3 As shown in the figure, the upper surface 122 of the top metal layer 120 is exposed.

[0065] The substrate 105 may be a wafer made of, for example, a semiconductor material. This semiconductor material may include, for example, silicon in crystalline form (Si). In alternative embodiments, the substrate may be made of other elemental semiconductors, such as germanium, or may contain compound semiconductors such as silicon carbide (SiC), gallium arsenide (GaAs), gallium carbide, gallium phosphide, indium arsenide (InAs), indium phosphide (InP), silicon germanium, silicon germanium carbide, gallium arsenide, or gallium indium phosphide. In a particular embodiment, the substrate is silicon.

[0066] Alternatively, substrate 105 may be a semiconductor die containing one or more integrated circuits. Integrated circuits are constructed from electrically conductive and electrically insulating materials of different patterns to create useful components. Suitable examples of integrated circuit components may include, but are not limited to, active components (e.g., transistors), passive components (e.g., capacitors, inductors, resistors, and similar passive components), or combinations thereof. For example, the substrate may be a complementary metal-oxide-semiconductor (CMOS) device.

[0067] The intermetallic layer 110 and the top metal layer 120 can generally be formed of any conductive metal. Examples of such metals include copper, aluminum, nickel, chromium, gold, germanium, silver, titanium, tungsten, platinum, tantalum, ruthenium, cobalt, rhenium, palladium, or zirconium; composite materials such as TiN, WN, or TaN; or alloys thereof. For example, the metal can be deposited by vapor deposition or sputtering, plating, chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), or other suitable methods. In a particular embodiment, the intermetallic layer 110 and the top metal layer 120 are each formed of copper.

[0068] The IMD layer can be formed by any suitable means, including CVD, PVD, thermal oxidation, or other suitable methods. Chemical mechanical planarization (CMP) or selective etching can be used to remove excess deposited material. In some specific embodiments, the IMD layer is formed of silicon nitride (SiN).

[0069] It should be noted that the intermetallic layer 110, the top metal layer 120, and the IMD layer 130 can be formed in various ways. For example, the intermetallic layer can be deposited and patterned, then the top metal layer can be deposited and patterned, and then the IMD layer can be deposited. If the intermetallic layer 110 and the top metal layer 120 are made of the same metal, a single metal layer can be deposited and patterned, and then the IMD layer can be deposited. As another example, a first dielectric layer can be formed using a first groove, then the intermetallic layer can be deposited into the groove, then a second dielectric layer can be formed using a second groove, and the top metal layer can be deposited into the second groove, wherein the two dielectric layers together form the IMD layer.

[0070] Next, refer to Figure 4 ,exist Figure 2 In step 320, a first adhesive layer 140 is formed on the top metal layer 120 and the IMD layer 130. Then, Figure 2 In step 325, a main dielectric layer 150 is formed on the first adhesive layer 140. Figure 2 In step 340, a second adhesive layer 180 is formed on the main dielectric layer 150. The resulting structure is... Figure 4 As shown in the figure. In some specific embodiments, the main dielectric layer is formed of silicon nitride (SiN).

[0071] The first adhesive layer 140 and the second adhesive layer 180 are generally made of any material that causes adhesion between the base layer 190 and the main dielectric layer 150. In some specific embodiments, the two adhesive layers are made of titanium. The adhesive layers can be formed, for example, by vapor deposition or sputtering, CVD, PVD, or ALD.

[0072] Next, as Figure 5A and Figure 5B As shown, the second adhesive layer 180 is patterned to form a groove opening 182, as... Figure 2 As indicated in step 345. The second adhesive layer 180 is also patterned to form an annular opening 184, as shown. Figure 2 As indicated in step 350. Note that the formation of these two openings is... Figure 2 The process is identified as two separate steps, but when both openings are formed, they are formed together in the same etching step. One or two steps are required. Reference number 186 indicates the exposed side of the second adhesive layer. (As...) Figure 5B As shown in the plan view, an annular opening 184 surrounds a recess opening 182. The main dielectric layer 150 is exposed through both openings 182 and 184. The recess opening is formed above or on the top metal layer 120.

[0073] Then, in Figure 2 In step 355 shown, and as Figure 6 As shown, the main dielectric layer 150 is partially etched to form a groove 160 above the top metal layer 120. In other words, the groove does not completely penetrate the main dielectric layer, and the first adhesive layer is not exposed via the groove. This partial etching is performed through the groove opening in the second adhesive layer 180. The etching time is controlled to control the depth of the groove 160. This is accomplished by forming a mask (e.g., a photoresist layer) and then performing partial etching through the mask.

[0074] Then, in Figure 2 In step 360 shown, and as Figure 7A and Figure 7B As shown, a groove 160 in the main dielectric layer 150 is patterned to form a step extending down to the first adhesive layer 140. The patterning process includes forming a mask that exposes a portion of the groove, and then etching down through the mask into the first adhesive layer. This patterning / etching step forms the step 170. The groove is now formed by an upper groove portion 162 and a lower groove portion 166. Now refer to Figure 7B In addition to the second adhesive layer 180 and the main dielectric layer 150 in the annular opening 184, the step 170 and the first adhesive layer 140 are now also exposed.

[0075] If needed, Figure 2 In the optional step 365 shown, and as follows Figures 8A to 8C As shown, the first adhesive layer 140 in the groove 160 is etched to form a through hole 220 from the groove 160 to the top metal layer 120. Continuing, in Figure 2 In step 370, a protective material 210 is deposited in the annular opening 184. The protective material forms a layer in the annular opening 184 covering the exposed side 186 of the second adhesive layer 180. Figure 8B It is along Figure 8A The Y-axis sectional view shown is taken by line BB, which does not pass through the perforation. Figure 8C It is along Figure 8A The Y-axis cross-sectional view shown is taken by line CC, which passes through the perforation 220. The protective material 210 is a different metal from the metal used to form the second adhesive layer 180, and therefore has a different etching selectivity than the second adhesive layer. Thus, the protective material will not be etched by the material used to etch the second adhesive layer. In a particular embodiment, the protective material is copper or nickel, or made of the same material as the base layer. Again, the perforation is optional and not required.

[0076] Then, in Figure 2 In step 375 shown, and as Figure 9As shown, a substrate material is deposited over the second adhesive layer and into the groove to form a substrate layer 190. The substrate material also fills the perforations (if present). It should be emphasized again that the substrate layer does not need to have a uniform thickness and may, for example, have a pillar shape located above the groove. The substrate material can be any conductive metal as previously described. In some specific embodiments where the protective material and the substrate material are the same material, the protective material and the substrate material can be deposited in the same deposition step.

[0077] Then, in Figure 2 In step 380 shown and returning to the reference Figure 1A An annular via 200 is etched through the protective material layer 210 down to the main dielectric layer 150. The protective material thus separates the annular via from the second adhesive layer 180. Therefore, the final structure is... Figure 1A As shown in the image.

[0078] Figure 10 This is a flowchart illustrating a second method 302 according to some embodiments. The second method 302 is used to form a substrate for a MEMS device 104 and to form one or more chemical stop structures to reduce etching of the adhesion layer. Some steps of the method are also described below. Figures 11 to 13 As shown in the image.

[0079] Figure 10 The second method shown is different from Figure 2 The first method shown is characterized in that, in step 330, the main dielectric layer 150 is partially etched before the formation of the second adhesive layer 180. Figure 11 The structure is shown after the main dielectric layer 150 is partially etched to form the groove 160.

[0080] Then, in step 340, a second adhesive layer 180 is formed on the main dielectric layer. It should be noted that the second adhesive layer is formed on the main dielectric layer as a conformal film. Figure 12 The structure following steps 345 to 350 is shown. As can be seen here, in this embodiment, the second adhesive layer 180 is present on the surface of the upper raised portion 176 and the surface of the step 170, but still does not contact the first adhesive layer 140. The annular opening 184 in the second adhesive layer 180 is also visible. Figure 13 The structure is shown after steps 360 to 380 are performed to deposit protective material 210, form base plate layer 190 and form annular through hole 200.

[0081] Figure 14 This is a flowchart illustrating a third method 303 according to some embodiments. The third method 303 is used to form a substrate for the MEMS device 102 and to form one or more chemical stop structures to reduce etching of the adhesive layer. Some steps of the method are also described below. Figure 15 and Figure 16As shown in the image.

[0082] Figure 14 The third method shown is different from Figure 2 The first method shown involves forming a recess 160 in the main dielectric layer 150 above the top metal layer 120 in step 335, but etching the recess down to the first adhesive layer 140. Then, a second adhesive layer 180 is deposited on the main dielectric layer 150. An optional step 342 may be performed after step 335 or 340, in which etching is performed in the recess down through the first adhesive layer 140 to the top metal layer 120 to form a through-hole. Figure 15 The resulting structure is shown. In this embodiment, the second adhesive layer 180 then contacts the first adhesive layer 140. Additionally, there is no... Figure 2 The first method shown (see also the first method shown) Figure 1A )or Figure 10 The second method shown (see also the second method shown) Figure 12 Step 170 in the ) Since the groove has already been formed, there is no need to form a groove opening in the second adhesive layer. Figure 16 The structure is shown after steps 350 to 375 are performed to deposit protective material 210 and form base plate layer 190. Figure 1E The structure is shown after the annular through-hole 200 is formed in step 380.

[0083] The apparatus and method of this invention include several different dielectric structures. Such dielectric structures can generally be made from any suitable combination of dielectric materials, but the properties of any particular layer can also be further defined. Examples of dielectric materials may include silicon dioxide (SiO2), silicon nitride (Si3N4), silicon carbide (SiC), hafnium dioxide (HfO2), zirconium dioxide (ZrO2), aluminum oxide (Al2O3), and silicon oxynitride (SiO2). x N y ), hafnium oxynitride (HfO) x N y ) or zirconium oxynitride (ZrO) x N y ), or hafnium silicate (HSixOy), or zirconium silicate (ZrSi) x O y ) or silicon carbide (SiCxO) y N z Alternatively, it can be hexagonal boron nitride (hBN). Other dielectric materials may include tantalum oxide (Ta2O5), nitrides such as silicon nitride, polycrystalline silicon, phosphosilicate glass (PSG), fluorosilicate glass (FSG), undoped silicate glass (USG), high-stress undoped silicate glass (HSUSG), and borosilicate glass (BSG).

[0084] It should also be noted that some traditional steps have not been explicitly described in the above discussion. For example, a pattern / structure can be formed in a given layer by applying a photoresist layer, patterning the photoresist layer, developing the photoresist layer, and then etching.

[0085] Generally, photoresist layers can be applied, for example, by spin coating or by spraying, roller coating, dip coating, or extrusion coating. Typically, in spin coating, a substrate is placed on a rotating stage, which may include a vacuum chuck for holding the substrate in the stage. The photoresist composition is then applied to the center of the substrate. The speed of the rotating stage is then increased to uniformly diffuse the photoresist from the center of the substrate to its periphery. The rotational speed of the stage is then fixed, which controls the final thickness of the photoresist layer.

[0086] Next, the photoresist composition is baked or cured to remove the solvent and harden the photoresist layer. In some specific embodiments, baking is performed at a temperature of about 90°C to about 110°C. Baking can be carried out using a hot plate, oven, or similar equipment. Thus, a photoresist layer is formed on the substrate.

[0087] The photoresist layer is then patterned by exposure to radiation. The radiation can be any wavelength of light carrying the desired mask pattern. In a particular embodiment, extreme ultraviolet (EUV) light with a wavelength of approximately 13.5 nanometers is used for patterning, thus allowing for a smaller feature size. This results in some portions of the photoresist layer being exposed to radiation, while other portions remain unexposed. This exposure causes some portions of the photoresist to become soluble in the developer, while other portions remain insoluble.

[0088] Following exposure to radiation, an additional photoresist baking step (post-exposure baking (PEB)) can be performed. For example, this can help release acid leaving groups (ALGs) or other molecules that are important in the chemically amplified photoresist.

[0089] The photoresist layer is then developed using a developer. The developer can be an aqueous solution or an organic solvent. During the development step, the soluble portions of the photoresist layer are dissolved and washed away, leaving the photoresist pattern. A common example of a developer is an aqueous solution of tetramethylammonium hydroxide (TMAH). Generally, any suitable developer can be used. Sometimes, post-development baking or "hard baking" is performed to stabilize the photoresist pattern after development, thereby achieving optimal performance in subsequent steps.

[0090] Continuing, some portions of the layer beneath the patterned photoresist layer are now exposed. Etching transfers the photoresist pattern to the layer beneath the patterned photoresist layer. After use, the patterned photoresist layer can be removed, for example, at high temperatures using various solvents (e.g., N-methylpyrrolidone (NMP) or alkaline media or other stripping agents), or by dry etching using oxygen plasma.

[0091] Generally, any etching steps described herein may be performed using wet etching, dry etching, or plasma etching processes (e.g., reactive ion etching (RIE) or inductively coupled plasma (ICP) or combinations thereof), as appropriate. Etching may be anisotropic. Depending on the material, etchants may include carbon tetrafluoride (CF4), hexafluoroethane (C2F6), octafluoropropane (C3F8), trifluoromethane (CHF3), difluoromethane (CH2F2), fluoromethane (CH3F), fluorinated carbon, nitrogen (N2), hydrogen (H2), oxygen (O2), argon (Ar), xenon (Xe), xenon difluoride (XeF2), helium (He), carbon monoxide (CO), carbon dioxide (CO2), fluorine (F2), chlorine (Cl2), hydrogen bromide (HBr), hydrofluoric acid (HF), nitrogen trifluoride (NF3), sulfur hexafluoride (SF6), boron trichloride (BCl3), ammonia (NH3), bromine (Br2), nitrogen trifluoride (NF3), or similar materials or combinations thereof in different ratios. For example, hydrofluoric acid and ammonium fluoride can be used for wet etching of silicon dioxide. Alternatively, silicon dioxide can be dry-etched using various mixtures of CHF3, O2, CF4 and / or H2.

[0092] For example, chemical mechanical polishing (CMP) can be used to planarize surfaces. Typically, CMP is performed using a rotating stage with a polishing pad. The substrate is attached to a rotating carrier. A slurry or solution containing various chemicals and abrasives is dispensed onto the polishing pad or wafer substrate. During polishing, both the polishing pad and the carrier rotate, causing mechanical and chemical effects on the surface of the wafer substrate and / or on the top layer above the surface, thereby removing unwanted material and producing a highly planar surface. A post-CMP cleaning step is then performed using a rotating scrubbing brush and washing fluid to clean one or both sides of the wafer substrate.

[0093] MEMS devices incorporating the MEMS structure of this invention include chemical stop structures that reduce or prevent erosion of the adhesive layer using etching chemicals such as hydrogen peroxide or potassium hydroxide. This reduces substrate peeling and improves the robustness of the MEMS structure. MEMS devices can be used in various applications, such as ion beam lithography or charge beam lithography.

[0094] Therefore, some embodiments of this invention relate to a method for forming a substrate for a MEMS device. A first adhesive layer is formed on a top metal layer. A main dielectric layer is formed on the first adhesive layer. A second adhesive layer is formed on the main dielectric layer. The second adhesive layer is patterned to form a recessed opening and an annular opening surrounding the recessed opening. The main dielectric layer is partially etched to form a recess above the top metal layer. A protective material is then deposited in the annular opening covering the side of the second adhesive layer. In some embodiments, the recess is also etched down to the first adhesive layer to form a step in the main dielectric layer. If necessary, further etching can be performed within the recess to form a through-hole reaching the top metal layer. Substrate material is then deposited on the second adhesive layer (and into the recess, if present). An annular via is then etched down through the protective material (and substrate material) to the main dielectric layer. The protective material separates the annular via from the second adhesive layer.

[0095] In some examples, the method of forming the substrate of a MEMS device further includes etching the groove down to the first adhesive layer before depositing the substrate material to form a step in the main dielectric layer. In some examples, the method of forming the substrate of a MEMS device further includes forming an intermetallic layer on a substrate before forming the first adhesive layer, forming the top metal layer on the intermetallic layer, and forming an intermetallic dielectric layer around the intermetallic layer and the top metal layer. In some examples, the first adhesive layer and the second adhesive layer are made of titanium. In some examples, the protective material is a different metal from the second adhesive layer. In some examples, the protective material is copper or nickel. In some examples, the substrate material is a metal. In some examples, the protective material is the same material as the substrate material. In some examples, the annular via has a taper angle of 30° to 135°. In some examples, the protective material has a width of up to 10 micrometers. In some examples, the step has a width of up to 100 micrometers. In some instances, the annular via has a minimum width of 0.1 micrometers to 100 micrometers. In some instances, the top metal layer is formed of copper. In some instances, the second adhesive layer is present on the step in the main dielectric layer.

[0096] Various embodiments also disclose a MEMS structure including a top metal layer and a first adhesive layer above the top metal layer. A main dielectric layer exists on the first adhesive layer. The main dielectric layer includes a stepped groove. A second adhesive layer exists on the main dielectric layer. The second adhesive layer includes a groove opening above the groove and an annular opening. A protective material covers the sides of the second adhesive layer in the annular opening. A base plate layer covers the second adhesive layer and fills the groove. An annular via passes through the base plate layer and the protective material and extends downward to the main dielectric layer. The protective material separates the annular via from the second adhesive layer.

[0097] In some instances, the groove in the main dielectric layer includes steps. In some instances, the microelectromechanical system device further includes a through-hole extending from the groove through the first adhesive layer to the top metal layer.

[0098] Various embodiments further disclose a MEMS structure including a top metal layer and a first adhesive layer located above the top metal layer. A main dielectric layer exists on the first adhesive layer. A second adhesive layer exists on the main dielectric layer. The second adhesive layer includes an annular opening. A protective material covers the sides of the second adhesive layer in the annular opening. A base plate layer covers the second adhesive layer. An annular via extends down through the base plate layer and the protective material to the main dielectric layer. The protective material separates the annular via from the second adhesive layer.

[0099] Continuing, various embodiments also disclose a MEMS structure including a top metal layer and a first adhesive layer situated above the top metal layer. A main dielectric layer exists on the first adhesive layer. The main dielectric layer includes a stepped groove. A second adhesive layer exists on the main dielectric layer. The second adhesive layer includes a groove opening above the groove and an annular opening. A base plate layer covers the second adhesive layer and fills the groove. An annular via extends through the base plate layer to reach the main dielectric layer.

[0100] Other methods for forming a chemical stop structure between a first adhesive layer and a second adhesive layer are also disclosed in various embodiments. A first adhesive layer is formed on a top metal layer. A main dielectric layer is formed on the first adhesive layer. A second adhesive layer is formed on the main dielectric layer. A groove opening is formed in the second adhesive layer. The main dielectric layer is partially etched to form a groove. The groove is then further etched down to the first adhesive layer to form a step in the main dielectric layer. A substrate material is deposited into the groove. The substrate material is different from the second adhesive layer and forms a chemical stop structure.

[0101] In some instances, the method for forming a chemical stop structure between a first adhesive layer and a second adhesive layer further includes the following steps: forming an annular opening around the groove opening located in the second adhesive layer; depositing a protective material covering the side of the second adhesive layer in the annular opening; and etching an annular via through the protective material and down to the main dielectric layer, wherein the protective material separates the annular via from the second adhesive layer.

[0102] Additional methods for forming chemical stop structures in MEMS structures are also disclosed in various embodiments. A main dielectric layer is formed on a first adhesive layer. A groove is formed in the main dielectric layer. A second adhesive layer is then formed on the main dielectric layer. An annular opening is formed in the second adhesive layer around the groove. A protective material is deposited in the annular opening covering the side of the second adhesive layer. A substrate material is deposited on the second adhesive layer and into the groove. An annular via is etched through the protective material and down to the main dielectric layer. The protective material forms a chemical stop structure.

[0103] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A microelectromechanical system (MEMS) device, characterized in that, include: Top metal layer; A first adhesive layer is located above the top metal layer; A main dielectric layer is located on the first adhesive layer, and the main dielectric layer includes grooves; The second adhesive layer is located on the main dielectric layer, and the second adhesive layer includes a groove opening and an annular opening located above the groove; Protective material, covering the side of the second adhesive layer in the annular opening; A base layer that covers the second adhesive layer and fills the groove; as well as An annular through-hole passes through the base plate layer and extends downwards to the main dielectric layer.

2. The microelectromechanical system device according to claim 1, characterized in that, The groove in the main dielectric layer includes steps.

3. The microelectromechanical system device according to claim 2, characterized in that, The second adhesive layer exists on the step in the main dielectric layer.

4. The microelectromechanical system device according to claim 1, characterized in that, It also includes a perforation that extends from the groove through the first adhesive layer to the top metal layer.

5. The microelectromechanical system device according to claim 1, characterized in that, The protective material separates the annular through-hole from the second adhesive layer.

6. The microelectromechanical system device according to claim 1, characterized in that, The annular through-hole has a taper angle of 30° to 135°.

7. The microelectromechanical system device according to claim 1, characterized in that, The protective material has a width of up to 10 micrometers.

8. The microelectromechanical system device according to claim 2, characterized in that, The steps have a width of up to 100 micrometers.

9. The microelectromechanical system device according to claim 8, characterized in that, The annular through-hole has a minimum width ranging from 0.1 micrometers to 100 micrometers.

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