Magnetic-Field Sensing Device
Apparatus and associated methods may relate to Magneto-Resistive Sensing Devices (MRSDs). In accordance with an exemplary embodiment, an MRSD comprises an underlying semiconductor device and a magneto-resistive sensor. In some exemplary embodiments, the semiconductor device is processed through most of a standard process flow. After the standard process flow, in various embodiments, a planarization step may be performed to create a more planar top surface. In some embodiments, the magneto-resistive material, which may be made from a Nickel-Iron alloy, called Permalloy, is deposited on the planar surface. A layer of interconnect metallization also may reside in this top region. The magneto-resistive material may contact the topmost layer of metallization of the semiconductor device via contact openings in the planarized surface. In some embodiments, the magneto-resistive material may similarly contact the topmost layer of metallization through these contact openings. The magneto-resistive material resides directly above the underlying circuitry.
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This application is a Continuation of U.S. Non-Provisional application Ser. No. 13/890,462, entitled “Magnetic-Field Sensing Device,” and filed by Chilcote, et al. on May 9, 2013, the entire disclosure of which is incorporated herein by reference.
TECHNICAL FIELDVarious embodiments relate generally to magneto-resistive (MR) sensors.
BACKGROUNDMagneto-Resistive Sensing Devices (MRSDs) are used to detect the presence of a magnetic field. Many of these magneto-resistive sensors are made of a material called Permalloy. Permalloy is a nickel-iron alloy. These sensors are used to detect the earth's magnetic field in compass applications. They are used to sense the proximity of a magnet, and are used in conjunction with magnets to determine rotational speeds of engines and other rotary devices. These sensors are also used to detect the stored information on disk drives of computers. Some applications of MRSDs allow a switch to be thrown by holding a magnet close to the sensor. Other applications allow a state to be set by non-contact means.
Many applications of MRSD are in portable and/or handheld devices. Such applications are often battery powered. Small device size and small device weight are both positive attributes of such instruments. Low power consumption allows such instruments to operate for long periods of time between battery charging and replacement. Furthermore, the smaller one can make the components of an instrument, the more functionality can be designed into the saved space or the instrument can be made to be smaller and lighter. Lower-power components can similarly be traded for either additional power consuming components or for longer battery life.
SUMMARYApparatus and associated methods may relate to Magneto-Resistive Sensing Devices (MRSDs). In accordance with an exemplary embodiment, an MRSD comprises an underlying semiconductor device and a magneto-resistive sensor. In some exemplary embodiments, the semiconductor device is processed through most of a standard process flow. After the standard process flow, in various embodiments, a planarization step may be performed to create a more planar top surface. In some embodiments, the magneto-resistive material, which may be made from a Nickel-Iron alloy, called Permalloy, is deposited on the planar surface. A layer of interconnect metallization also may reside in this top region. The magneto-resistive material may contact the topmost layer of metallization of the semiconductor device via contact openings in the planarized surface. In some embodiments, the magneto-resistive material may similarly contact the topmost layer of metallization through these contact openings. The magneto-resistive material resides directly above the underlying circuitry.
Various embodiments may achieve one or more advantages. For example, some embodiments may eliminate the need for using two separate components, a semiconductor device and a separate sensor. In another embodiment, by locating the MR sensor on the same device as the circuitry, lower power performance may be achievable. Some embodiments permit the circuit real-estate to be doubly used in this fashion, as the magneto-resistive element may be largely overlapping the underlying circuitry. In another embodiment, the location of the NiFe material is deposited on top of a semiconductor device that has many dielectric layers. These dielectric layers may permit the Fe, which may be considered a contaminant for semiconductor processing, to be isolated from the underlying circuitry by these dielectric layers. Some implementations may be advantageously constructed in part in a first facility that is substantially free of iron contamination, and then supplemented with an iron-containing magneto-resistive layer in a second manufacturing facility to eliminate possible contamination of the first facility.
The details of various embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description and drawings, and from the claims.
Like reference symbols in the various drawings indicate like elements.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTSThis figure shows two distinct semiconductor transistors. The first semiconductor transistor depicted is a vertical NPN bipolar transistor 130. The second semiconductor transistor depicted is an NMOS field-effect transistor 135. As shown in this exemplary figure, the magneto-resistive material 120 is arranged so as to be located directly above these two active devices 130, 135. Many other devices, such as resistors, capacitors, and inductors, or other transistor types can be made using appropriate geometries of the first and second regions' various layers.
This exemplary figure also depicts two layers of metallization in the second region of the device. A first layer of metallization 150 is labeled as “Metal-1” in the figure. A second layer of metallization 155 is labeled as “Metal-2” in the figure. In this example, the first layer of metal is deposited in a thin layer that is approximately parallel with the surface of region one. For example, a wire 160 is shown with an exemplary cross sectional dimension that is approximately a rectangle whose long dimension is largely parallel with the substrate. Some Metal-1 features, 165 and 170 for example, have a contact portion that descends and makes contact with the region one semiconductor devices. The second layer of metal is shown to have similar characteristics, being largely parallel to the region-one surface and having contact features. But the contact features of the second layer of metal make contact with the first layer metal in these instances.
Region three in this exemplary figure perhaps begins with the planarization layers that are above the second layer of metal 155. In this example, a layer of spin-on glass or SOG 175 has been deposited to smooth out the topographically featured surface 180, upon which the SOG resides. Another dielectric layer 185 is deposited above the SOG 175 in this exemplary cross-section. The magneto-resistive material 120 resides immediately above this dielectric layer 185. A third layer of metal interconnect 125 is then shown, and labeled as “Metal-3” in the figure. This third layer of metal has a contact 190, not too dissimilar to those of Metal-2 and Metal-1. The Metal-3 contact 190 is shown to contact a Metal-2 feature 195 located directly beneath it. In this exemplary figure, the Metal-3 directly contacts the Metal-2 in these contact features. The Metal-3 feature also contacts the magneto-resistive material everywhere that it touches it. In this way, the underlying circuitry has a way to connect to the magneto-resistive material deposited directly above the semiconductor devices.
Many ways exist to electrically connect the interconnecting electrical paths in the second region to the magneto-resistive material in the third region. In some embodiments, the magneto-resistive layer may be connected to the underlying metal interconnections by first etching via in the dielectric layers intervening between the top-most layer of region-two metallization and then depositing the magneto-resistive material such that it makes physical contact with the top-most layer of region-two metallization in the etched contact regions. In other embodiments, the magneto-resistive material may be electrically connected to the top-most layer of region-two metallization by way of an additional layer of metallization. In such embodiments, for example, after the contacts have been etched to the top-most layer of region-two metallization, a layer of magneto-resistive material may be deposited. This magneto-resistive material may then be selectively removed by an etch step. Then another layer of metallization may be deposited. This metallization may then connect to both the un-etched magneto-resistive material and the top-layer of region-two metallization exposed in the contacts that were previously etched in the intervening dielectric materials. Other permutations of the above steps may also be performed to provide the electrical connection of the magneto-resistive material to the underlying metal interconnect layers. For example, the last metal deposition and magneto-resistive deposition may be transposed so that the top-layer of metallization is first deposited and etched, and then the magneto-resistive layer may be deposited and then etched. In this way, the magneto-resistive layer may be connected via the metal deposited immediately before the magneto-resistive layer's deposition.
Although various embodiments have been described with reference to the Figures, other embodiments are possible. For example, many different processing techniques exist to create the semiconductor devices. Some processes have, for example, heterojunction bipolar devices. A third region, containing the magneto-resistive material, could be applied to a wide variety of underlying semiconductor devices, including for example the heterojunction bipolar device process described.
In various embodiments, the MRSD may be manufactured using alternate magneto-resistive materials and/or compositions. In an exemplary embodiment, a NiFe layer may be thinner or thicker. In another embodiment, the Fe concentration may be greater than 19% or less than 19%. Such changes in composition and thickness may have desirable circuit consequences regarding response to a magnetic field or regarding circuit power consumption. In accordance with another embodiment, the TaN cladding layers may be composed of different chemical compositions. TiN or other refractory metal nitrides may be used for example. In another exemplary embodiment, the cladding layer thicknesses may be smaller or greater. Such thicknesses may be selected, for example, to provide for better step coverage over surface topologies.
In accordance with another embodiment, planarization may be performed using methods other than SOG. For example, in one exemplary embodiment Chemical Mechanical Polishing (CMP) may be used instead of SOG or in addition to SOG. Other planarization methods using anisotropic etch-back techniques may also be used either in addition to SOG and CMP or in lieu of SOG or CMP. In some exemplary embodiments, the metal-3 layer of the third region may be deposited, patterned and etched before the magneto-resistive layer is deposited.
A number of implementations have been described. Nevertheless, it will be understood that various modification may be made. For example, advantageous results may be achieved if the steps of the disclosed techniques were performed in a different sequence, or if components of the disclosed systems were combined in a different manner, or if the components were supplemented with other components. Accordingly, other implementations are within the scope of the following claims.
Claims
1-20. (canceled)
21. A magnetic-field sensing device, comprising:
- a first region, comprising semiconductor devices on a substrate;
- a second region disposed on the first region, comprising at least two vertically separated layers of interconnecting electrical paths; and
- a third region disposed on the second region and comprising a magneto-resistive material disposed to vertically overlap and arranged in electrical communication with the semiconductor devices in the first region via the interconnecting electrical paths in the second region, wherein the first and second regions are separated by a first dielectric layer and the second and third regions are separated by a second dielectric layer,
- wherein the magneto-resistive material is disposed directly on the second dielectric layer, and electrical communication between the magneto-resistive material and the semiconductor devices in the first region is made through one or more vias in the second dielectric layer that are filled with a non-magneto-resistive metal material.
22. The device of claim 21, wherein the second region comprises at least three vertically separated layers of interconnecting electrical paths.
23. The device of claim 21, wherein the semiconductor devices in the first region comprise CMOS transistors.
24. The device of claim 21, wherein the semiconductor devices in the first region comprise bipolar transistors.
25. The device of claim 21, wherein the semiconductor devices in the first region comprise both CMOS transistors and bipolar transistors.
26. The device of claim 21, wherein the magneto-resistive material of the third region comprises Permalloy material.
27. The device of claim 21, wherein the third region further comprises a layer of metal disposed to provide electrical connection to the topmost metal layer of the second region and to the magneto-resistive material of the third region.
28. The device of claim 21, wherein the magneto-resistive material of the third region overlaps more than fifty percent of the underlying first region comprising semiconductor devices
29. The device of claim 21, wherein the magneto-resistive material further comprises a layer of TaN disposed on top of a magnetic sensing layer.
Type: Application
Filed: Aug 5, 2015
Publication Date: Feb 4, 2016
Applicant: HONEYWELL INTERNATIONAL, INC. (Morristown, NJ)
Inventors: Jason Chilcote (Morristown, NJ), Richard Alan Davis (Morristown, NJ)
Application Number: 14/819,320