Darlington pair bipolar junction transistor sensor

Abstract

A Darlington pair sensor is disclosed. The Darlington pair sensor has an amplifying / horizontal bipolar junction transistor (BJT) and a sensing / vertical BJT and can be used as a biosensor. The amplifying bipolar junction transistor (BJT) is arranged horizontally on a substrate. The amplifying BJT has a horizontal emitter, a horizontal base, a horizontal collector, and a common extrinsic base / collector. The common extrinsic base / collector is an extrinsic base to the amplifying BJT. The sensing BJT has a vertical orientation to the amplifying BJT. The sensing BJT has a vertical emitter, a vertical base, an extrinsic vertical base, and a common extrinsic base / collector (common with the amplifying BJT). The common extrinsic base / collector serves as the sensing BJT collector. The extrinsic vertical base is separated into a left extrinsic vertical base and a right extrinsic vertical base to obtain a sensing BJT with two separated (dual) bases, a sensing base and a control base. The Darlington pair sensor has high in-situ signal amplification with low noise and uses the board space efficiently.

Description

[Technical Field]

[0001] This invention relates to semiconductor circuits. More specifically, this invention relates to sensors created by semiconductor circuits and used therein. [Background technology]

[0002] Some sensors, particularly those used to sense the properties of biological fluids, i.e., biosensors, are typically constructed using ion-sensitive transistors. These ion-sensitive transistors, such as Darlington pair transistors, provide sensing and amplification (for example, at the base of one of the transistors in the Darlington pair). Amplification is necessary to integrate the sensor with other circuits (e.g., readout and control circuits) because biosensor signals are generally very weak.

[0003] The monolithic integration of these sensors / biosensors with circuits such as readout / control circuits is crucial for energy-efficient, high-performance, and mass-deployable systems. In particular, amplification circuits need to be monolithically integrated close to the sensor / biosensor for efficient amplification of weak signals. Furthermore, keeping the sensor close to the amplification circuit eliminates the accumulation and buildup of noise that can occur when the sensor is isolated over a longer distance from the amplification circuit.

[0004] These sensors / biosensors are used in highly integrated sensing / biosensing systems, including systems used for artificial intelligence (AI), healthcare monitoring, point-of-care diagnostics, the Internet of Things (IoT), and wearable devices. Some biosensing applications involve mobile (portable and wearable) sensing technologies that can non-invasively monitor health using biological fluids such as sweat, saliva, and urine. These biosensors have the potential to provide cost-effective and enhanced healthcare, particularly in the treatment of chronic diseases. These biosensor technologies are desirable to provide mobile and online monitoring of patients to make healthcare delivery more efficient and cost-effective.

[0005] There is a need to provide accurate, highly sensitive, small, and mobile sensors, particularly biosensors, that can be easily integrated into semiconductor circuits and mass-produced inexpensively by standard semiconductor processing, while possessing reduced noise and strong signal amplification. [Overview of the Initiative]

[0006] A Darlington pair sensor is disclosed. The Darlington pair sensor comprises an amplification / horizontal bipolar junction transistor (BJT) and a sensing / vertical BJT.

[0007] An amplified bipolar junction transistor (BJT) is positioned horizontally on a substrate. The amplified BJT has a horizontal emitter, horizontal base, horizontal collector, and a common extrinsic base / collector. The common extrinsic base / collector is the extrinsic base for the amplified BJT. The common extrinsic base / collector is in contact with the horizontal base and is positioned vertically above it.

[0008] The sensing BJT has a vertical orientation relative to the amplification BJT. The sensing BJT has a vertical emitter, a vertical base, an exogenous vertical base, and a common exogenous base / collector (common with the amplification BJT) that functions as the sensing BJT collector. The exogenous vertical base is separated into a left exogenous vertical base and a right exogenous vertical base. Thus, the sensing BJT has two (dual) bases. The left exogenous vertical base can be the sensing base, and the right exogenous vertical base can be the control base, or vice versa.

[0009] The left exogenous vertical base is in contact with the left side of the vertical base, and the right exogenous vertical base is in contact with the right side of the vertical base. The left and right exogenous vertical bases are physically separated from each other by the vertical base and are electrically coupled to each other via the vertical base.

[0010] Alternative configurations and BJT polarities are disclosed along with a method for creating a Darlington pair BJT sensor. The Darlington pair BJT sensor may be used as a biosensor. [Brief explanation of the drawing]

[0011] Various embodiments of the present invention are described in more detail below with reference to the accompanying drawings, which are briefly described herein. The drawings illustrate stages of various apparatuses, structures, and related methods of the present invention.

[0012] [Figure 1] This is a cross-sectional view of the initial structure for a Darlington pair BJT sensor, including a semiconductor substrate layer, a BOX / insulating layer, and a horizontal / lateral BJT base layer.

[0013] [Figure 2] This is a cross-sectional view of the initial structure with the pre-exogenous base / collector layer added.

[0014] [Figure 3] This is a cross-sectional view showing an intermediate structure used to create a common exogenous base / collector.

[0015] [Figure 4] It is a cross-sectional view showing an intermediate structure after the mask etching step has created a horizontal base.

[0016] [Figure 5] It is a cross-sectional view showing an intermediate structure after ion implantation on the side surface of the horizontal (true) base.

[0017] [Figure 6] After the horizontal emitter and horizontal collector for the horizontal / transverse BJT are formed by the epitaxial growth step, the horizontal emitter and collector are combined with a common extrinsic base / collector to form an intermediate structure on both sides of the horizontal (true) base that forms the horizontal / transverse bipolar junction transistor (BJT) portion of the Darlington pair BJT sensor. It is a cross-sectional view.

[0018] [Figure 7] It is a cross-sectional view showing an intermediate structure after filling the intermediate structure with an interlayer dielectric (ILD) and applying chemical mechanical polishing (CMP).

[0019] [Figure 8] It is a cross-sectional view showing an intermediate structure after CMP removes the hard mask and exposes the common extrinsic base / collector.

[0020] [Figure 9] It is a cross-sectional view showing an intermediate structure after formation of a bottom spacer on the horizontal (or transverse / amplifying) BJT.

[0021] [Figure 10] It is a cross-sectional view showing an intermediate structure after formation of a sacrificial placeholder material on the bottom spacer.

[0022] [Figure 11] It is a cross-sectional view showing an intermediate structure after formation of a top spacer on the sacrificial placeholder material and subsequent formation of an oxide layer on the top spacer.

[0023] [Figure 12] This is a cross-sectional view showing the intermediate structure after trench formation by selective (stopping) etching through the oxide layer, top spacer, and bottom spacer through the sacrificial placeholder material.

[0024] [Figure 13] This is a cross-sectional view showing the intermediate structure after the formation of a thin vertical oxide layer on the trench wall, created by oxidation of the sacrificial placeholder material.

[0025] [Figure 14] This is a cross-sectional view showing the intermediate structure after selective etching (selective to the common exogenous base / collector material) has removed the bottom spacer at the base of the trench, exposing the common exogenous base / collector, which allows the common exogenous base / collector to become the collector for the vertical / sensing BJT portion of the Darlington pair BJT sensor.

[0026] [Figure 15] This is a cross-sectional view showing the intermediate structure after the formation of the vertical base region within the trench that will serve as the base for the vertical / sensor BJT.

[0027] [Figure 16] This is a cross-sectional view showing the intermediate structure after polishing (e.g., CMP) the vertical base region back down to the oxide layer to form the vertical base of the vertical BJT portion of the Darlington pair BJT sensor.

[0028] [Figure 17] This is a cross-sectional view showing the intermediate structure after further oxide deposition covers the vertical base and the structure has been planarized, for example, by CMP.

[0029] [Figure 18] This is a cross-sectional view showing the intermediate structure after deposition of the base region mask on an oxide, where the vertical projection of the base region mask (not shown) overlaps on both sides of the horizontal base.

[0030] [Figure 19] This is a cross-sectional view showing the intermediate structure after the etching stage, where the exposed oxide, exposed top spacer, and exposed sacrificial material have been removed down to just above the bottom spacer.

[0031] [Figure 20] This is a cross-sectional view showing the intermediate structure after the remaining sacrificial material has been removed.

[0032] [Figure 21] This is a cross-sectional view showing the intermediate structure after the removal of a thin vertical oxide layer on a vertical base.

[0033] [Figure 22] This is a cross-sectional view showing the intermediate structure after growth of the doped exogenous vertical base material surrounding the vertical base.

[0034] [Figure 23] As will be explained in more detail in the series of Figures 38A, 38B, 39A, 39B, 40A, 40B, 41A, 41B, 42A, and 42B below ("Series of Separation Figures"), this is a cross-sectional view showing the intermediate structure after removal of the base region mask and deposition of the base separation hard mask, where the base separation hard mask is used to separate the left and right sides of the extrinsic vertical base.

[0035] [Figure 24] As further explained in the series of separation diagrams, this is a cross-sectional view showing the intermediate structure after the doped exogenous vertical base material, which is not protected by the base separation hard mask, has been removed by etching.

[0036] [Figure 25] This is a cross-sectional view showing the intermediate structure after the structural spaces / voids have been filled with interlayer dielectrics (ILDs).

[0037] [Figure 26]This is a cross-sectional view showing the intermediate structure after removal of the base separation hard mask and planarization / CMP.

[0038] [Figure 27] This is a cross-sectional view showing the intermediate structure after the deposition of the emitter mask.

[0039] [Figure 28] This is a cross-sectional view showing the intermediate structure after the unprotected oxide and the top of the vertical base have been recessed, exposing the exposed top surface of the vertical base.

[0040] [Figure 29] This is a cross-sectional view showing the intermediate structure after growth of the vertical emitter on the exposed top surface of the vertical base, which results in the formation of the vertical BJT portion of the Darlington pair BJT sensor.

[0041] [Figure 30] This is a cross-sectional view showing the intermediate structure after the emitter mask has been removed and an optional CMP (Chemical Modification) has been performed.

[0042] [Figure 31] This is a cross-sectional view showing the intermediate structure after the ILD covers the vertical / sensor BJT portion of the Darlington pair BJT sensor, fills the structural space, and is subsequently CMP'd.

[0043] [Figure 32] This is a cross-sectional view showing the intermediate structure after masked etching has formed a sensing trench.

[0044] [Figure 33] This is a cross-sectional view showing the intermediate structure after lateral etching on the isolated sensing side of a doped extrinsic vertical base material, which creates a sense contact void.

[0045] [Figure 34]This is a cross-sectional view showing the intermediate structure after the sensing trench and sense contact void have been filled with metal, i.e., sensing trench metal filler.

[0046] [Figure 35] This is a cross-sectional view showing the intermediate structure after the sensing trench metal filler has been partially etched.

[0047] [Figure 36] This is a cross-sectional view showing the intermediate structure after removing the remaining metal filler while leaving the metal sliver sensing surface intact.

[0048] [Figure 37] This is a cross-sectional view showing a completed embodiment of a Darlington pair BJT sensor after the formation of the external contacts.

[0049] [Figure 38A] In the series of separated diagrams, this is a cross-sectional view showing the intermediate structure after growth of the doped exogenous vertical base material surrounding the vertical base.

[0050] [Figure 38B] This is a top view of the intermediate structure shown in Figure 38A.

[0051] [Figure 39A] This is a cross-sectional view showing the intermediate structure after the base region mask has been removed in the series of separation diagrams.

[0052] [Figure 39B] This is a top view of the intermediate structure shown in Figure 39A.

[0053] [Figure 40A] This is a cross-sectional view showing the intermediate structure after the deposition of the base separation hard mask in the separation diagram series.

[0054] [Figure 40B] This is a top view of the intermediate structure shown in Figure 40A.

[0055] [Figure 41A] This is a cross-sectional view showing the intermediate structure after removing the unprotected, doped extrinsic vertical base material surrounding the vertical base, separating the extrinsic vertical base material into the right and left extrinsic vertical bases.

[0056] [Figure 41B] This is a top view of the intermediate structure shown in Figure 41A.

[0057] [Figure 42A] This is a cross-sectional view showing the intermediate structure after interlayer dielectric (ILD) filling.

[0058] [Figure 42B] This is a top view of the intermediate structure shown in Figure 42A.

[0059] [Figure 43] This is a flowchart showing how to create a Darlington pair BJT sensor.

[0060] [Figure 44] This is a circuit diagram of one embodiment of a Darlington pair sensor. [Modes for carrying out the invention]

[0061] The embodiments of the present invention are not limited to the exemplary methods, apparatus, structures, systems, and devices disclosed herein, but are more broadly applicable to other alternative and broader methods, apparatus, structures, systems, and devices that will become apparent to those skilled in the art in consideration of this disclosure.

[0062] In addition, it should be understood that the various layers, structures, and / or regions shown in the attached drawings are not drawn to scale, and that one or more commonly used types of layers, structures, and / or regions may not be explicitly shown in the given drawings. This does not imply that layers, structures, and / or regions that are not explicitly shown are omitted from the actual device.

[0063] In addition, certain elements may be omitted from the drawings for clarity and / or brevity if the explanation does not necessarily focus on such omitted elements. Furthermore, the same or similar reference numerals used throughout the drawings are used to indicate the same or similar features, elements, or structures, and therefore, a detailed description of the same or similar features, elements, or structures may not be repeated for each drawing.

[0064] The semiconductor devices, structures, and methods disclosed in embodiments of the present invention may be used in applications, hardware, and / or electronic systems. Suitable hardware and systems implemented using embodiments of the present invention may include, but are not limited to, personal computers, communication networks, e-commerce systems, portable communication devices (e.g., mobile phones and smartphones), solid-state media storage devices, expert systems and artificial intelligence systems, functional circuits, neural networks, and the like. Systems and hardware incorporating semiconductor devices and structures constitute the intended embodiments of the present invention.

[0065] As used herein, “height” refers to the vertical size of an element (e.g., a layer, trench, hole, opening, etc.) measured from the bottom surface to the top surface of the element and / or measured relative to the surface on which the element is placed, in a section view or elevation view.

[0066] Conversely, "depth" refers to the vertical size of an element (e.g., a layer, trench, hole, opening, etc.) measured from the top surface to the bottom surface in a cross-sectional or elevation view of the element. Terms such as "thick," "thickness," "thin," or their derivatives may be used in place of "height" where appropriate.

[0067] As used herein, “side” and “left” or “right” refer to the side of an element (e.g., a layer, an opening, etc.), for example, the left or right side as shown in the drawing.

[0068] Where used herein, “width” or “length” refers to the size of an element in a drawing (e.g., a layer, trench, hole, opening, etc.) measured from one side to the opposite surface of that element. Terms such as “thick,” “thickness,” “thin,” or their derivatives may be used in place of “width” or “length” where indicated.

[0069] As used herein, terms such as “upper,” “lower,” “upper,” “right,” “left,” “vertical,” “horizontal,” “top,” “bottom,” and their derivatives refer to the disclosed structures and methods as oriented in the drawings. For example, as used herein, “vertical” refers to a direction perpendicular to the top surface of the substrate in the elevation view, and “horizontal” refers to a direction parallel to the top surface of the substrate in the elevation view.

[0070] As used herein, unless otherwise specified, terms such as “on,” “overlying,” “atop,” “on top,” “positioned on,” or “positioned atop” mean that the first element is on top of the second element, and that intervening elements may exist between the first and second elements. As used herein, unless otherwise specified, the terms “directly,” or “in contact,” or “directly in contact” used in relation to terms such as “on,” “overlying,” “atop,” “on top,” “positioned on,” or “positioned atop,” or “disposed on,” mean that the first and second elements are connected without any intervening elements, such as an intermediate conductive, insulating, or semiconductor layer present between the first and second elements.

[0071] It is understood that these terms may be affected by the orientation of the device being described. For example, the meaning of these descriptions may change if the device is inverted, but the descriptions remain valid because they describe the relative relationships between the features of the invention.

[0072] A Darlington pair of bipolar junction transistors (BJTs) configured as a dual-base Darlington pair BJT sensor is disclosed. The Darlington pair BJT sensor comprises, in the pair of BJTs, a first or vertical or sensing BJT transistor and a second or lateral or amplifying BJT transistor.

[0073] The first BJT transistor in a Darlington pair BJT is a vertical / sensing BJT having a vertical emitter, vertical base, and vertical collector (which also functions as the horizontal exogenous base of the second horizontal / lateral BJT transistor). The vertical / sensing BJT has a dual base consisting of a right exogenous vertical base and a left exogenous vertical base. The vertical BJT is also referred to as a sensor / sensing transistor or dual-base BJT without loss of generality.

[0074] The left and right exogenous vertical bases are physically separated from each other by the vertical base and electrically coupled to each other via the vertical base. The left exogenous vertical base is in contact with the left side of the vertical base, and the right exogenous vertical base is in contact with the right side of the vertical base.

[0075] The second part / transistor portion of a Darlington pair BJT sensor is a horizontal BJT having a horizontal emitter, a horizontal collector, and a horizontal base. The horizontal BJT also has a horizontal extrinsic base that is in contact with the horizontal base and is vertically above it. The horizontal extrinsic base is common to and identical to the vertical collector of a vertical BJT; that is, they are one in the same element. Without loss of generality, the horizontal BJT is also referred to as a lateral BJT, integrated BJT, or amplified BJT.

[0076] A vertical / dual-base / sensing BJT has an intrinsic gain associated with the BJT. The disclosed Darlington pair BJT sensor boosts this gain "in-situ" (without the need to transmit the signal obtained by the sensing BJT to an external amplifier circuit). In some embodiments, the effective gain of the Darlington pair BJT is the product of the dual-base sensing (vertical) BJT gain and the horizontal / lateral / integrated BJT gain. Since the horizontal exogenous base of the lateral BJT is the same element as the vertical collector of the vertical BJT, there is essentially no connection distance between the collector of the vertical / sensing BJT and the base of the lateral BJT, meaning that any noise occurring over this "in-situ connection" is dramatically reduced.

[0077] The vertical / dual-base / sensing BJT is aligned perpendicular to the lateral BJT, meaning the sensor BJT is positioned vertically above the horizontal / lateral BJT. Therefore, no additional surface area on the substrate is essentially required for the Darlington pair BJT sensor other than that used by the lateral BJT. Accordingly, the Darlington pair BJT sensor enables high-density and area-efficient integration with semiconductor circuits using standard semiconductor fabrication methods.

[0078] The present invention enables the creation of Darlington pair BJT sensors using a complementary Darlington pair configuration, also known as a Cycla configuration, in which the sensing BJT and the lateral BJT have different polarities. For example, the complementary Darlington pair BJT sensors described herein may consist of a lateral BJT having npn polarity and a sensing BJT having pnp polarity (Figures 1 to 42A and 44), or a lateral BJT having pnp polarity and a sensing BJT having npn polarity.

[0079] Figure 1 is a cross-sectional view of an initial structure 100 for a Darlington pair BJT sensor, which includes a semiconductor substrate layer 105, a BOX / insulating layer 110, and a horizontal / lateral BJT base layer 150.

[0080] In some embodiments, the substrate / bulk 105 is made from one or more semiconductor materials. Non-limiting examples of suitable substrate / bulk 105 materials include Si (silicon), strained Si, Ge (germanium), SiGe (silicon germanium), Si alloys, Ge alloys, III-V semiconductor materials (e.g., GaAs (gallium arsenide), InAs (indium arsenide), InP (indium phosphide), indium gallium arsenide (InGaAs), or aluminum arsenide (AlAs)), II-VI materials (e.g., CdSe (cadmium selenide), CdS (cadmium sulfide), CdTe (cadmium telluride), ZnSe (zinc selenide), ZnS (zinc sulfide), or ZnTe (zinc telluride)), or any combination thereof.

[0081] In an exemplary embodiment, the substrate 105 is silicon.

[0082] In some silicon-on-insulator (SOI) embodiments, the BOX layer 110 is an embedded oxide layer (e.g., SiO2) embedded in the substrate (wafer) 105 to a depth typically ranging from less than 100 nanometers (nm) to several micrometers, depending on the application. The thickness of the BOX layer 110 is typically in the range of about 20 nanometers (nm) to about 150 nm.

[0083] The BOX layer 110, and alternatively the insulating layer 110, prevent current leakage between adjacent semiconductor components constructed in contact with these layers. The BOX layer 110 and the substrate 105 are well known.

[0084] An exemplary and alternative insulating layer 110 includes a known PTS-doping layer, which is also used to prevent current leakage from the active layer constructed in contact with the punch-through stopper (PTS) layer.

[0085] In one embodiment, a commercially available silicon germanium-on-insulator (SGOI) wafer comprising a SiGe layer 150, a carrier substrate 105, and a BOX layer 110 is used. Doping of the SiGe layer can be achieved by known techniques such as ion implantation and annealing. In some embodiments, epitaxy using in-situ doping can be used to increase the thickness of the SiGe layer 150 to a desired thickness.

[0086] In one embodiment having an NPN transverse BJT, the semiconductor layer 150 is a silicon germanium (SiGe) layer having p-type doping that forms a p-type SiGe on-insulator substrate (SGOI) 150.

[0087] Alternatively, a bulk silicon wafer 105, available with the PTS layer 110 and the SiGe layer 150, may be used.

[0088] These techniques and materials are publicly known.

[0089] To form an alternative PNP lateral BJT embodiment, n-type doping materials, such as phosphorus (P), arsenic (As), and antimony (Sb), are used to dope the semiconductor (e.g., SiGe) layer 150.

[0090] Figure 2 is a cross-sectional view of the initial structure 200 having a preliminary exogenous base / collector layer 250 deposited on structure 100.

[0091] In some embodiments, a preliminary exogenous base / collector layer 250 is epitaxially grown on the semiconductor layer 150. The thickness of the preliminary exogenous base / collector layer 250 is between 10 nanometers (nm) and 50 nm, but thinner or thicker layers may also be used.

[0092] The terms "epitaxially grown and / or deposited" and "epitaxially grown and / or deposited" refer to the growth of semiconductor material on a deposition surface of a semiconductor material, where the grown semiconductor material has the same crystalline properties as the semiconductor material on the deposition surface. In the epitaxial deposition process, the chemical reactants provided by the source gas are controlled and system parameters are set so that the atoms to be deposited have enough energy to move around on the surface and orient themselves relative to the crystalline arrangement of atoms on the deposition surface before arriving at the deposition surface of the semiconductor substrate. Thus, each semiconductor layer in the epitaxial semiconductor material stack has the same crystalline properties as the deposition surface on which it is formed.

[0093] Examples of various epitaxial growth process apparatuses that may be used in this application include, for example, rapid thermochemical vapor deposition (RTCVD), low-energy plasma deposition (LEPD), ultra-high vacuum chemical vapor deposition (UHVCVD), atmospheric pressure chemical vapor deposition (APCVD), and molecular beam epitaxy (MBE). The temperature for epitaxial deposition is typically in the range of 550°C to 900°C. Generally, higher temperatures result in faster deposition, but faster deposition can lead to crystal defects and film cracking. In some embodiments, the gas source for epitaxial growth may include a mixture of silicon-containing gas sources and / or germanium-containing gas sources. Examples of silicon gas sources include silane, disilane, trisilane, tetrasilane, hexachlorodisilane, tetrachlorosilane, dichlorosilane, trichlorosilane, and combinations thereof. Examples of germanium gas sources include Germanan, sigermann, or combinations thereof. In some embodiments, epitaxial SiGe alloys can be formed from a source gas containing a compound containing silicon and germanium. A carrier gas such as hydrogen, nitrogen, or helium may be used. For epitaxial growth of the layer, an appropriate dopant type is added to the precursor gas or gas mixture. In some embodiments of the channel material layer, the dopant is not typically present in or added to the precursor gas or gas mixture.

[0094] In some embodiments, the layers are grown by an integrated epitaxy process. In the integrated epitaxy process, the structure is epitaxially grown continuously while the type and / or concentration of the dopant is changed at various points in time and over different periods, creating various layers with different dopants and dopant concentrations. Some temperature adjustments may also be made for one or more of the layers during epitaxial growth.

[0095] In embodiments where the lateral BJT is an NPN BJT, the extrinsic base layer 250 is p-doped. In embodiments where the lateral BJT is a PNP BJT, the extrinsic base layer 250 is n-doped.

[0096] The dopants may include, for example, p-type dopants selected from the group of boron (B), gallium (Ga), indium (In), and thallium (Tl) in the epitaxial layer 250, and n-type dopants selected from the group of phosphorus (P), arsenic (As), and antimony (Sb) in an alternative exogenous base layer 250, at various concentrations. For example, in an unrestricted example, the dopant concentration range is 1 × 10⁻⁶. 18 cm -3 ~3×10 21 cm -3 , or preferably 2 × 10 20 cm -3 ~1 × 10 21 cm -3 It could be between these two points.

[0097] Figure 3 is a cross-sectional view showing the intermediate structure 300 used to create the common exogenous base / collector 350.

[0098] The hard mask 375 is deposited within a pattern on the extrinsic base layer 250, where the common extrinsic base / collector 350 will be formed.

[0099] The hard mask 375 is a protective dielectric material, such as a lithography protective material. In some embodiments, the hard mask 375 material includes, but is not limited to, one of the following materials: silicon nitride (SiN), silicon boron nitride (SiBCN), silicon oxycarbonite (SiOCN), and silicon oxynitride (SiON).

[0100] In some embodiments, the hard mask 375 is made from silicon nitride (SiN) or silicon oxide (SiO2) and deposited by a standard technique such as physical vapor deposition (PVD).

[0101] A selective etching step for the material within the horizontal / lateral BJT base layer 150 removes all material in the extrinsic base layer 250 that is not protected by (and not beneath) the hard mask 375. The remaining material (protected by the hard mask 375) becomes the common extrinsic base / collector 350.

[0102] The spacer 325 material is then conformally deposited around the common extrinsic base / collector 350 by a known process, such as atomic layer deposition (ALD). A known vertical etching, such as reactive ion etching (RIE), removes the spacer material from the horizontal surface, leaving the spacer 325 on the sides of the common extrinsic base / collector 350.

[0103] In some embodiments, vertical etching is selective for the materials constituting the hard mask 375 and the horizontal / lateral BJT base layer 150.

[0104] In some embodiments, the resulting width / thickness of the spacer 325 is between 3 nm and 10 nm. In alternative embodiments, the thickness of the spacer 325 is approximately 5 nm to 7 nm.

[0105] In some embodiments, the spacer 325 is made from a material comprising: dielectric oxides (e.g., silicon oxide), dielectric nitrides (e.g., silicon nitride (SiN), SiBCN, SiCN, and SiBN), dielectric oxynitrides (e.g., SiOCN), SiCO, and SiC, or any combination thereof.

[0106] It should be noted that selective etching is an etching process that has chemical actions and conditions that remove certain materials and / or layers but not others (materials that are not etched). Alternatively, non-etchable materials are etched by the chemical actions of the etching process, but at a much lower etching rate than the materials being removed. Here, the measure of selectivity may be the ratio between the etching rates of two given materials. For example, an etching chemical action "selective to" a material means that the etching solution does not remove that material, or removes it at a slower rate. Therefore, using a selective etching chemical action on the materials constituting the hard mask 375 and spacer 325 removes the material in the extrinsic base layer 250 without removing (or minimally removing) the materials constituting the hard mask 375 and spacer 325.

[0107] Figure 4 is a cross-sectional view showing the intermediate structure 400 after the etching stage of the masked base has created the horizontal base 450. Selective directional etching is performed on the materials constituting the BOX / insulating layer 110, the hard mask 375, and the spacer 325, as described above with respect to Figure 3.

[0108] The remaining material 450 within the semiconductor layer 150, i.e., the material protected by the hard mask 375 and spacer 325 (and located below its vertical projection), becomes the horizontal base 450.

[0109] Figure 5 is a cross-sectional view showing the intermediate structure 500 after ion implantation 575 on the side 576 of the horizontal base 450 / 550 to be implanted.

[0110] In some embodiments, when the horizontal / lateral BJT is PNP, i.e., when the horizontal / lateral intrinsic base 550 is N-type doped, the embodiment of ion implantation 575 is high-temperature BF2 implantation. In some embodiments, when the horizontal / lateral BJT is NPN, i.e., when the horizontal / lateral intrinsic base 550 is P-type doped, the embodiment of ion implantation 575 is high-temperature As or P implantation.

[0111] In some lateral NPN BJT embodiments, ion implantation 575 is angle implantation 562 / 576 of a first dopant on the emitter side of the horizontal / lateral base 550 (or lateral intrinsic base 550) and angle implantation 576 / 564 of a second dopant on the collector side of the lateral intrinsic base 550. The polarity and / or species of the second dopant may be the same as or different from that of the first dopant.

[0112] The implantation can be at either a high or low temperature, however, high-temperature implantation is preferred. Typically, the implantation is angled ion implantation. These ion implantation methods are well known. This ion implantation step is optional and may be omitted in some embodiments.

[0113] Figure 6 is a cross-sectional view showing the intermediate structure 600 after the lateral emitter 652 and lateral collector 654 for the horizontal / lateral BJT 652 / 550 / 654 / 350 have been formed by the epitaxial growth stage as described above. The lateral emitter 652 is in contact with the emitter side 562 of the lateral intrinsic base 550, and the lateral collector 654 is in contact with the collector side 564 of the lateral intrinsic base 550. The lateral / horizontal emitter 652 and lateral / horizontal collector 654 are physically, chemically, and electrically connected to their respective sides 562 / 564 of the lateral intrinsic base 550 to form the horizontal bipolar junction transistor (BJT) 652 / 550 / 654 / 350 of the Darlington pair BJT sensor.

[0114] Figure 7 is a cross-sectional view showing the intermediate structure 700 after the intermediate structure is filled with interlayer dielectric (ILD) 750 and the top surface 775 is subjected to chemical mechanical polishing (CMP).

[0115] ILD750 may be formed from low-k dielectric materials (having k<4.0) including, but not limited to, silicon oxide, spin-on glass, fluid oxide, high-density plasma oxide, boron silicate glass (BPSG), or any combination thereof. ILD750 may be deposited by deposition processes including, but not limited to, chemical vapor deposition (CVD), physical vapor deposition (PVD), plasma-enhanced CVD, atomic layer deposition (ALD), vapor deposition, chemical solution deposition, or similar processes.

[0116] CMP is a known process for leveling the top surface 775 of a structure 700.

[0117] Figure 8 is a cross-sectional view showing the intermediate structure 800 after the hard mask removal CMP has removed the hard mask 375 and exposed the common exogenous base / collector 350. In some embodiments, the hard mask removal CMP stops at the top surface 850 of the common exogenous base / collector 350 when the removal portion of the common exogenous base / collector 350 material is detected during the hard mask removal CMP. The hard mask removal CMP creates a flat surface of the structure 800 and exposes the top surface 850 of the common exogenous base / collector 350.

[0118] Figure 9 is a cross-sectional view showing the intermediate structure after the formation of the bottom spacer 950 on the horizontal (or lateral) BJT652 / 550 / 654 / 350.

[0119] The bottom spacer 950 may be made from a low-k dielectric formed according to a known process. The term “low-k dielectric” generally refers to an insulating material having a dielectric constant less than silicon dioxide, e.g., less than 3.9. Exemplary low-k dielectric materials include, but are not limited to, dielectric oxides (e.g., silicon oxide), dielectric nitrides (e.g., SiN, SiBCN), dielectric oxynitrides (e.g., SiOCN, SiCO), or any combination thereof, or similar. Other non-limiting examples of materials for the bottom spacer 950 include dielectric oxides (e.g., silicon oxide), dielectric nitrides (e.g., silicon nitride), dielectric oxynitrides, or any combination thereof.

[0120] The bottom spacer 950 material is deposited by a deposition process, such as CVD or PVD. The bottom spacer 950 can have a thickness of approximately 3 nm to 15 nm, or approximately 5 nm to 10 nm. The deposition process allows for precise control of the spacer 950 thickness.

[0121] In some embodiments, the bottom spacer is a dielectric nitride.

[0122] Figure 10 is a cross-sectional view showing the intermediate structure 1000 after the formation of the sacrificial placeholder material 1050 on the bottom spacer 950.

[0123] The sacrificial placeholder material 1050 is made from, for example, amorphous silicon (α-Si) or polycrystalline silicon (polysilicon). The sacrificial material 1050 can be deposited by deposition processes including, but are not limited to, PVD, CVD, plasma-enhanced chemical vapor deposition (PECVD), inductively coupled plasma chemical vapor deposition (ICPCVD), or any combination thereof. The sacrificial material has a thickness of about 10 nm to about 100 nm, or about 20 nm to about 50 nm. Known deposition techniques allow for precise control of the thickness of the sacrificial placeholder material 1050.

[0124] In some embodiments, the sacrificial placeholder material 1050 is amorphous silicon.

[0125] Figure 11 is a cross-sectional view showing the intermediate structure 1100 after the formation of the top spacer 1150 on the sacrificial placeholder material 1050 and the subsequent formation / deposition of the oxide layer 1175 on the top spacer 1150.

[0126] The top spacer 1150 is made from the same or similar material and using the same or similar deposition technique as that used to create the bottom spacer 950.

[0127] The oxide layer 1175 is deposited by known techniques, such as CVD or PVD, and is made from materials such as silicon boron nitride (SiBCN), silicon oxycarbonite (SiOCN), and silicon oxide.

[0128] In some embodiments, the oxide layer 1175 is made from silicon dioxide, and the top spacer 1150 is made from silicon nitride, SiN.

[0129] Figure 12 is a cross-sectional view showing the intermediate structure 1200 after the formation of a trench 1250 by selective (stopping) etching through the oxide layer 1175, the top spacer 1150, and the bottom spacer 950 through the sacrificial placeholder material 1050.

[0130] In some embodiments, trench etching may be performed in steps. For example, a first RIE may etch through the oxide layer 1175, the top spacer 1150, and partially through the sacrificial placeholder material 1050. A second RIE, selective for the material in the bottom spacer 950, may then be used to remove the remainder of the sacrificial placeholder material 1050.

[0131] Figure 13 is a cross-sectional view showing the intermediate structure 1300 after the formation of a thin vertical oxide layer 1350 on the wall portion 1355 of the trench 1250. The thin vertical oxide layer 1350 is created by oxidation of the sacrificial placeholder material 1050.

[0132] Exposure to plasma or any other method of oxidation creates a very thin oxide formation 1350 on the sidewalls 1355 of the sacrificial material 1050 within the trench 1250. The bottom spacer 950 protects the common extrinsic base / collector 350 from being oxidized by the plasma / oxidation.

[0133] FIG. 14 is a cross-sectional view showing an intermediate structure 1400 after selective etching (selective with respect to the common extrinsic base / collector 350 material) removes the bottom spacer 950 at the base 1450 of the trench 1250, exposing the common extrinsic base / collector 350 and enabling the common extrinsic base / collector 350 to also serve as the collector of the vertical / sensing BJT of the Darlington pair BJT sensor.

[0134] In some embodiments, the width of the trench is between 10 nm and 50 nm, although wider or narrower trenches may also be used.

[0135] FIG. 15 is a cross-sectional view showing an intermediate structure after formation of a vertical base region 1550 within the trench 1250 that becomes the vertical base of the vertical BJT.

[0136] The epitaxial growth of the base material within the vertical base region 1550 is lattice-matched to the common extrinsic base / collector 350 material. The vertical base region 1550 is a semiconductor material that grows epitaxially within the trench 1250 by known methods described above.

[0137] In some embodiments, a strained vertical base is formed by lattice-matching, but not exactly, the material within the vertical base region 1550 close to the lattice of the common extrinsic base / collector material.

[0138] In some embodiments, the base material within the vertical base region 1550 is doped with silicon germanium at a concentration of 10 18 cm -3 ~10 20 cm -3 and 1019 cm -3 ~5×10 19 cm -3 The concentrations in this range are more typical. If the vertical / sensing BJT has PNP polarity, the material within the vertical base region 1550 is N-doped. If the vertical / sensing BJT has NPN polarity, the material within the vertical base region 1550 is P-doped.

[0139] Figure 16 is a cross-sectional view showing the intermediate structure 1600 after polishing (e.g., CMP) the top of the vertical base region 1550, which is parallel to the surface 1676 of the oxide layer 1175. Planarization / CMP removes excess epitaxial growth above the surface 1676 of the oxide layer 1175, forming the vertical base 1650 of the vertical BJT portion of the Darlington pair BJT sensor.

[0140] Figure 17 is a cross-sectional view showing the intermediate structure 1700 after further oxide deposition has covered the surface 1676 of the previous oxide layer 1175, increasing its thickness and resulting in a thicker oxide layer 1775. The thicker oxide layer 1775 covers the vertical base 1650 and the surface 1676 of the structure 1600. The thicker oxide layer 1775 is planarized, for example, by CMP.

[0141] In some embodiments, the deposited oxide is the same material deposited by the same method as that of the oxide layer 1175.

[0142] Figure 18 is a cross-sectional view showing the intermediate structure 1800 after deposition of the base region mask 1850 on oxide 1775, where the vertical projection of the base region mask overlaps on both sides of the horizontal transverse intrinsic base 550. The base region mask 1850 is made from the material described above with respect to the mask and deposited using the method described above.

[0143] In some embodiments, the base region mask 1850 is fabricated from silicon nitride (SiN).

[0144] Figure 19 is a cross-sectional view showing the intermediate structure 1900 after a vertical etching step (e.g., RIE) has removed the exposed (not covered by the base region mask 1850) portion of the oxide layer 1775, the exposed portion of the top spacer 1150, and the exposed portion of the sacrificial material 1050. In some embodiments, the vertical etching is stopped at a point (determined experimentally) when some of the sacrificial material 1050 remains, enough to cover the bottom spacer 950.

[0145] Vertical etching leaves a void 1950 around the vertical base 1650 and the material 950 / 1150 / 1975 surrounding the vertical base 1650. The etched oxide layer 1975 is what remains from the oxide layer 1775 after this vertical etching step.

[0146] Figure 20 is a cross-sectional view showing the intermediate structure 2000 after the remaining sacrificial material 1050 has been removed, exposing the vertical oxide layer 1350 on the side of the vertical base 1650.

[0147] In some embodiments, the sacrificial placeholder material 1050 is amorphous silicon. In some embodiments, this material is removed by dry etching or exposure to ammonium hydroxide (NH4OH) at a temperature above room temperature. In some cases, removal is achieved using a hydrofluoric acid (HF) solution or dry chemical oxide etching.

[0148] Figure 21 is a cross-sectional view showing the intermediate structure 2100 after the removal 2150 of the thin vertical oxide layer 1350 on the sides surrounding the vertical base 1650. The removal of the thin vertical oxide layer 1350 on the sides increases the volume of the void 2155 above the bottom spacer 950.

[0149] In some embodiments, the vertical oxide layer 1350 is realized using short exposure to HF etching or by other known techniques.

[0150] Figure 22 is a cross-sectional view showing the grown intermediate structure 2200 of the doped exogenous vertical base material 2250 surrounding the vertical base 1650.

[0151] The extrinsic vertical base material 2250 is a semiconductor material that can epitaxially grow from the vertical base 1650 while filling the void 2155 and surrounding it. In some embodiments, the extrinsic vertical base material 2250 can cover some or all of the sides of the top spacer 1150 and the sides of the etched oxide layer 1975.

[0152] In some embodiments, the extrinsic vertical base material 2250 may be a defective epitaxy. "Defective epitaxy" means that the extrinsic vertical base material 2250 may contain structural defects such as stacking defects and point defects. It should be noted that since the vertical base 1650 is used solely as a seed layer for the epitaxial growth of the extrinsic vertical base material 2250, none of these defects will propagate to the vertical base 1650.

[0153] It should be noted that defects within the extrinsic vertical base material 2250 do not appear to adversely affect the operation or performance of the finished Darlington pair sensor.

[0154] Furthermore, it should be noted that the shape of the extrinsic vertical base material 2250 shown in Figure 22 is merely illustrative.

[0155] In some alternative embodiments, the extrinsic vertical base material 2250 may be large-grained polycrystalline silicon (polysilicon). Rather than epitaxially growing the extrinsic vertical base material 2250, the polysilicon may be deposited by deposition processes including, but not limited to, PVD, CVD, plasma-enhanced chemical vapor deposition (PECVD), inductively coupled plasma chemical vapor deposition (ICPCVD), or any combination thereof.

[0156] The exogenous base material 2250 has the same doping polarity as the vertical base 1650 and a higher doping concentration than the vertical base 1650. The doping concentration of the exogenous base material 2250 is, for example, 10 20 cm -3 ~3×10 21 cm -3 This can be within a certain range. In some embodiments, the exogenous base material 2250 has a wider band gap than the vertical base 1650. As is known, this can be advantageous in reducing base leakage. For example, if the vertical base 1650 is composed of Ge or SiGe, the exogenous base 2250 may be composed of SiGe with a higher concentration than that of the vertical base 1650.

[0157] Figure 23 is a cross-sectional view showing the intermediate structure 2300 after the removal of the base region mask 1850 and the deposition of the base separation hard mask 2350. As will be described in more detail in the series of Figures 38A, 38B, 39A, 39B, 40A, 40B, 41A, 41B, 42A, and 42B below ("Series of Separation Diagrams"), the base separation hard mask 2350 is used to physically separate the left 2250L and right 2250R sides of the extrinsic vertical base 2250 material.

[0158] Figure 24 is a cross-sectional view showing the intermediate structure after, for example, the extrinsic vertical base material 2250, which is not protected (below) the base separation hard mask 2350, has been removed by etching during vertical RIE. The remaining extrinsic vertical base material 2250 forms the extrinsic vertical base 2450, which has left 2450L and right 2450R sides that are electrically and physically separated from each other. The process of physically separating the extrinsic vertical base 2450 into left 2450L and right 2450R sides is further described in the series of separation diagrams below.

[0159] For example, as described below, some of the extrinsic vertical base material 2250 is removed by etching, exposing the ends of the vertical base 1650 toward and out of Figure 24, and as a result, the left 2450L and right 2450R sides of the vertical base 2450 remaining after vertical etching are physically separated.

[0160] In some embodiments, the left 2450L and right 2450R sides of the vertical base 2450 are physically separated by the vertical base 1650. The left extrinsic vertical base 2450L is in contact with the left side of the vertical base 1650, and the right extrinsic vertical base 2450R is in contact with the right side of the vertical base 1650.

[0161] The vertical etching / RIE is located above the bottom spacer 950, leaving a spatial void 2460 surrounding the remaining etched oxide layer 1975, the top spacer 1150, and the extrinsic vertical base 2450.

[0162] Figure 25 is a cross-sectional view showing the intermediate structure 2500 after the spatial voids 2460 have been filled with interlayer dielectric (ILD) 2550 using the materials and deposition methods described above.

[0163] Figure 26 is a cross-sectional view showing the intermediate structure after planarization / CMP, where the base separation hard mask 2350 has been removed and the tops of the etched oxide layers 1975 and ILD2550 have been leveled.

[0164] Figure 27 is a cross-sectional view showing the intermediate structure 2700 after deposition of the emitter mask 2750 using pattern deposition, or deposition and subsequent patterning to position the mask opening 2775 above the vertical base 1650. The emitter mask 2750 is deposited using the well-known mask material described above and by the well-known deposition method described above.

[0165] Figure 28 is a cross-sectional view showing the intermediate structure 2800 after the unprotected portion of the etched oxide layer 1975 has been recessed, exposing the top surface 2850 of the vertical base 1650. The recessing of the etched oxide layer 1975 can be performed, for example, by directional RIE which is selective for the material in the top spacer 1150. The recessing leaves a spatial void 2875 above the top surface 2850 of the vertical base 1650.

[0166] Figure 29 is a cross-sectional view showing the intermediate structure 2900 after filling the spatial void 2875 by epitaxial growth of the vertical emitter 2950 on the exposed top surface 2850 of the vertical base 1650, resulting in the formation of the vertical / sensing / dual-base BJT 350 / 1650 / 2950 / 2450 of the Darlington pair BJT sensor.

[0167] The vertical emitter material 2950 (or the top portion of the vertical emitter material 2950) can be created from defective epitaxy. Note that since the vertical base 1650 is used only as a seed layer for the epitaxial growth of the vertical emitter material 2950, ​​none of these defects will propagate into the vertical base 1650.

[0168] It should be noted that these defects in the extrinsic vertical emitter material 2950 do not appear to have any adverse effect on the operation or performance of the finished Darlington pair sensor.

[0169] If the vertical / sensing BJT350 / 1650 / 2950 / 2450 is of the PNP type, the vertical emitter material 2950 is P-doped. If the vertical / sensing BJT350 / 1650 / 2950 / 2450 is of the NPN type, the vertical emitter material 2950 is N-doped. Doping is performed by the publicly known techniques described above.

[0170] In an alternative embodiment, the vertical emitter material 2950 is large-grained polycrystalline silicon (polysilicon). Rather than epitaxially growing the vertical emitter material 2950, ​​the polysilicon may be deposited within the spatial void 2875 by a deposition process including, but not limited to, PVD, CVD, plasma-enhanced chemical vapor deposition (PECVD), inductively coupled plasma chemical vapor deposition (ICPCVD), or any combination thereof.

[0171] The vertical emitter material 2950 is, for example, 10 20 cm -3 ~3×10 21 cm -3 It may have doping concentrations in the range of . In some embodiments, the bottom portion of the vertical emitter material 2950 is relatively low, for example, 10 19 cm -3 ~10 20 cm -3 The doping concentration can be in the range of . As is known, lower doping in the bottom portion may be advantageous in reducing bandgap narrowing and Auger recombination. In some embodiments, the vertical emitter material 2950 has a wider bandgap than the vertical base 1650. As is known, this may be advantageous in increasing the emitter transfer ratio and therefore increasing the BJT gain. For example, if the vertical base 1650 is composed of Ge or SiGe, the vertical emitter 2950 may be composed of SiGe with a higher concentration than that of the vertical base 1650.

[0172] Figure 30 is a cross-sectional view showing the intermediate structure 3000 after the emitter mask 2750 has been removed by CMP. Alternatively, the emitter mask 2750 may be selectively removed by known selective etching and subsequent optional CMP.

[0173] Figure 31 is a cross-sectional view showing the intermediate structure after the ILD deposition 3150 has covered the vertical / sensing BJT of the Darlington pair BJT sensor (including the vertical emitter 2950) above the lower spacer 950. Optional CMP may follow the ILD deposition. The ILD 3150 material and deposition method are as described above.

[0174] Figure 32 is a cross-sectional view showing the intermediate structure 3200 after masked etching has formed the sensing trench 3250. For example, the masked etching chemical action removes the exposed ILD3250 material and is selective for the bottom spacer 950 material. The width of the sensing trench 3250 may be in the range of 10 nm to 1 μm, but narrower and wider sensing trenches may also be used.

[0175] Figure 33 is a cross-sectional view showing the intermediate structure 3300 after lateral etching of one of the isolated sensing sides (here, the right side 2450R) of the doped extrinsic vertical base material 2450, which creates a sense contact void 3350 in contact with the sensing trench 3250.

[0176] Lateral etching is performed to remove material from the extrinsic vertical base 2450 on the side (left 2450L or right 2450R) that is in contact with the sensing trench 3250. Lateral etching creates a sense contact void 3350 on the side 2450L / 2450R of the extrinsic vertical base 2450 that is in contact with the sensing trench 3250, and as a result, any fluid (e.g., liquid and / or gas) entering the sensing trench 3250 comes into contact with the side 2450L / 2450R of the extrinsic vertical base 2450 that is in contact with the sensing trench 3250.

[0177] In some embodiments, the sense contact void 3350 is etched away to a depth of 10–50 nm into the extrinsic vertical base 2450 material. Other depths are conceivable.

[0178] Therefore, the sensing trench 3250 is in fluid communication with the sense contact void 3350 in such a way that any fluid within the sensing trench 3250 will come into contact with the respective separated sides 2450L / 2450R of the extrinsic vertical base 2450 (the side in question being 2450R, as shown in Figure 33).

[0179] Lateral etching to remove material from the exposed side of the exogenous base 2450 can be wet etching or gas etching. However, wet etching is more preferred.

[0180] Figure 34 is a cross-sectional view showing the intermediate structure 3400 after the sensing trench 3250 and sense contact void 3350 have been filled with metal, i.e., sensing trench 3250 metal filler 3450.

[0181] The sensing trenches 3250 and sense contact voids 3350 may be filled with ALD deposition of a metal or other conductive material 3450. Alternatively, the sensing trenches 3250 and sense contact voids 3350 may be lined with a layer of a metal or other conductive material using ALD deposition, for example. The remainder of the sensing trenches 3250 and sense contact voids 3350 may then be filled with deposition of a metal or other conductive material by a process such as CVD, PVD, or plating. In some embodiments, the sensing trenches 3250 and sense contact voids 3350 may be filled or lined with an insulating material such as a semiconductor or high-k dielectric instead of a metal or conductive material.

[0182] In some embodiments, the filler conductive material / metal 3450 is titanium nitride (TiN). However, other filler materials are conceivable. For example, the filler conductive material / metal 3450 may be selected due to its chemical and / or electrical reaction with a specific fluid or substance sensed in the sensing trench 3250, as will be described in more detail below.

[0183] Figure 35 is a cross-sectional view showing the intermediate structure 3500 after some of the trench metal filler 3450 has been partially etched to form the etched-back trench metal filler 3550.

[0184] In some embodiments, trench metal etch-back is performed using a chemical action to remove the filler conductive material / metal 3450 by timed wet etching. The timing of the wet etching may be determined experimentally. In alternative embodiments, vertical RIE is used to remove all metal in the sensing trench in a single operation. The etched trench metal filler 3550 may be a metal / substance specific to the material being sensed.

[0185] Figure 36 is a cross-sectional view showing the intermediate structure 3600 after the remaining trench metal filler 3550 has been removed, leaving the metal sliver sensing surface 3650. In some embodiments, the metal sliver sensing surface 3650 remains within the sense contact void 3350 and remains in electrical and physical contact with the 2450L / 2450R side (where 2450R is shown in Figure 36 as a non-limiting example) of the vertical extrinsic base 2450 adjacent to the sensing trench 3625 / 3250.

[0186] The remaining trench metal packing 3550 is removed using directional RIE. Thus, the sensing trenches 3625 / 3250 are reopened to create an open space for receiving, for example, a fluid (liquid or gas) containing the substance to be sensed 3670.

[0187] The metal sliver sensing surface 3650 may have a sensing surface height 3652 and a sensing surface area 3654, for example, between 50 nm and 1 μm. In some embodiments, the sensing surface area 3654 is approximately equal to the sensing surface height 3652 × the depth of the sensing trench 3250 / 3625 (in the direction toward or away from Figure 36). Increasing the sensing surface area 3654 increases the sensitivity of the Darlington pair sensor to the material 3670 to be sensed, which is located within the sensing trench 3250 / 3625. Note that in some embodiments, the sensing surface area 3654 does not have to be a flat surface and may be convex due to directional RIE.

[0188] The sensing substance 3670 (indicated as "xxx") may include, for example, molecules and / or ions of a material placed in the sensing trench 3250 / 3625, in a suspension and / or solution within a fluid (liquid and / or gas) in the sensing trench 3250 / 3625.

[0189] Accordingly, in some embodiments, the trench metal filler 3450 material determines the type of metallic / conductive material constituting the metallic sliver sensing surface 3650. In some embodiments, the trench filler 3450 is composed of a non-metallic / non-conductive material such as a high-k dielectric, and thus constitutes the high-k dielectric sliver sensing surface 3650. In some embodiments, the sensing surface 3650 may be functionalized with a material suitable for the species to be sensed. For example, if the sensing surface 3650 is composed of a high-k dielectric, a self-assembled organic monolayer may be used for functionalization using known methods.

[0190] As a non-limiting example, due to the reaction of the sliver sensing 3650 surface 3654 to a given substance to be sensed 3670, in some embodiments, a TiN trench metal filler 3450 material is selected to sense the sense substance hydrogen ions (e.g., pH) 3670, AgCl 3450 is selected to sense the chloride 3670, Au 3450 is selected to sense the DNA 3670, and the chemical reaction of a thiol material is selected to sense the protein 3670 (3450).

[0191] Therefore, the sensing trench 3250 / 3625 is a spatial void capable of receiving a fluid containing or being one or more sensed substances 3670, directed to contact and interact with the metal sliver sensing surface 3650 within the sensing trench 3250 / 3625.

[0192] It should be noted that, due to the symmetry of structure 3600, the sensing trench 3625 and the metal sliver sensing surface 3650 may be formed together such that the metal sliver sensing surface 3650 contacts either the left 2450L side or the right 2450R side of the extrinsic vertical base 2450. The side of the extrinsic vertical base 2450 in contact with the metal sliver sensing surface 3650 (either 2450L or 2450R, respectively) becomes the sensing base of the sensing / vertical BJT. Accordingly, the side of the extrinsic vertical base not in contact with the metal sliver sensing surface 3650 (either 2450R or 2450L, respectively) becomes the non-sensing base, controlled extrinsic vertical base, or control base of the sensing / vertical BJT. The sensing base and the control base are the two bases of the sensing / vertical BJT.

[0193] The metal sliver sensing surface is located between the sensing trench 3625 and each sensing base, and is electrically connected to each sensing base. As a non-limiting example, as shown in Figure 36, the sensing base is a right-side extrinsic vertical base 2450R, and the control (non-sensing) extrinsic vertical base (control base) is a left-side extrinsic vertical base 2450L.

[0194] In the described embodiment, the physical separation of the sides 2450L / 2450R of the extrinsic vertical base 2450 creates two separate (dual) base terminals, where the control bases 2450L / 2450R may be connected to an input (external) signal or bias, while the sensing base terminals are subject to electrical / chemical reactions of the sliver sensing 3650 surface 3654 via the material being sensed 3670. The control and sensor base terminals are electrically (e.g., electrostatically) coupled to each other, as in any dual-base BJT, and jointly determine the output characteristics of the BJT (e.g., current-voltage characteristics).

[0195] The Vertical / Sensor BJT350 / 1650 / 2950 / 2450 / 2450L / 2450R are dual-base Darlington pair BJT sensors, including the sensing base 2450R and control base 2450L as non-limiting examples.

[0196] Figure 37 is a cross-sectional view showing a completed embodiment of the Darlington pair BJT sensor 3700 after the formation of the external contacts 3150 / 3754 / 3756 / 3758. Functionalization of the sliver sensing surface 3650 is typically performed at this stage, if desired.

[0197] External contact 3150 connects to the horizontal emitter 652 of the horizontal / lateral BJT 652 / 550 / 654 / 350. External contact 3754 connects to the extrinsic base extrinsic vertical / control base 2450 (left side 2450L as a non-limiting example). External contact 3756 connects to the vertical emitter 2950 of the vertical / sensing BJT 2950 / 1650 / 350 / 2450 / 2450L / 2450R / 350. External contact 3758 connects to the horizontal collector 654 of the horizontal / lateral BJT 652 / 550 / 654 / 350.

[0198] In some embodiments, there are multiple external contacts 3150 and 3756, some of which are electrically connected to or from the drawing plane and are not shown in Figure 37.

[0199] External contacts 3150 / 3754 / 3756 / 3758 are formed by known metallization techniques. For example, external contact trenches are formed, for example, by laser cutting or patterned etching. The external contact conductor material is then deposited into the contact trenches. Exemplary contact conductor materials include elemental metals such as tungsten, cobalt, ruthenium, rhodium, zirconium, copper, aluminum, and platinum. In some embodiments, the contact conductor material is cobalt or tungsten. Any excess material in the external contact trenches can be removed by CMP.

[0200] Additional contacts can be created outside of structure 3700 to create alternative configurations for vertical / sensing BJTs and horizontal / lateral BJTs, depending on the polarity of each BJT in the BJT pair and the circuit design criteria. As a non-limiting example, an external emitter contact 3754 for a vertical / sensing BJT can be configured to be externally connected to an external collector contact 3758 for a horizontal / lateral BJT.

[0201] As explained above, lateral / amplifying BJTs and vertical / sensing BJTs can have different polarities. For example, a BJT can be composed of one of the following configurations: an amplified BJT is PNP and a sensing BJT is NPN, and an amplified BJT is NPN and a sensing BJT is PNP.

[0202] In an alternative configuration, two or more of the Darlington pair BJT sensors 3700 may be configured such that the sensing trenches 3625 of the first Darlington pair BJT sensor 3700 and one or more second Darlington pair BJT sensors 3700 are fluid-communicated and connected. Fluid communication means that a common fluid stream flows through each of the connected sensing trenches 3625 with little or no resistance to the fluid flow. This allows each of the connected Darlington pair BJT sensors 3700 to carry the common fluid through each of the connected sensing trenches 3625 so that each of the Darlington pair BJT sensors 3700 can sense one or more sensed substances 3670 in the common fluid flowing through the sensing trenches 3625. In this configuration, multiple types of sensed substances 3670 can be sensed in a single integrated sensor having multiple Darlington pair BJT sensors 3700.

[0203] Figure 38A is a cross-sectional view showing the grown intermediate structure 3800 of the doped extrinsic vertical base material 2250 surrounding the vertical base 1650 in a series of separated diagrams. See also the description of Figure 22 above. The base region mask 1850 rests on the etched oxide layer 1975, and the vertical projection of the base region mask 1850 (not shown) overlaps both sides and both ends (front and back, not shown) of the horizontal common extrinsic base / collector 350.

[0204] Figure 38B is a top view of the intermediate structure 3850 shown in Figure 38A, which shows the top surface of the base region mask 1850 and a portion of the surface of the unprotected (not beneath the base region mask 1850) extrinsic vertical base material 2250.

[0205] Please note again that the shape of the extrinsic vertical base material 2250 shown in Figures 38A and 38B is shown for illustrative purposes only, and that the actual shape of the extrinsic vertical base material 2250 may differ. Also note that the horizontal emitter 652, common extrinsic base / collector 350, lateral intrinsic base 550, spacer 825, and lateral collector 654 have been omitted for brevity.

[0206] Figure 39A is a cross-sectional view showing the intermediate structure 3900 after the base region mask 1850 has been removed, as described above, in the series of separation diagrams. Please refer to the explanation of Figure 23.

[0207] Figure 39B is a top view 3950 of the intermediate structure 3900 shown in Figure 39A, showing the etched oxide layer 1975 and the unprotected surface of the extrinsic vertical base material 2250.

[0208] Figure 40A is a cross-sectional view showing the intermediate structure 4000 after the deposition of the base separation hard mask 2350 in the separation diagram series.

[0209] Figure 40B is a top view 4050 of the intermediate structure shown in Figure 40A. The top surface of the deposited base separation hard mask 2350 is shown. The unprotected (not beneath the base separation hard mask 2350) top surface of the extrinsic vertical base material 2250 is also shown. The front edge 4222 and back edge 4224 of the base separation hard mask 2350 are shown, and as a result their vertical projections descending through the structure 4050 reveal the front 1650F and back edge 1650B of the vertical base 1650, respectively, as described below in Figure 41B. Accordingly, the base separation hard mask 2350 is "shorter" than the removed base region mask 1850.

[0210] Figure 41A is a cross-sectional view showing the intermediate structure 4100 after the unprotected, doped extrinsic vertical base material surrounding the ends 1650F / 1650B of the vertical base 1650 and the other volumes surrounding the vertical base 1650 has been removed down to the bottom spacer 950. This etching / removal separates the extrinsic vertical base 2450 material into the right extrinsic vertical base 2450R and the left extrinsic vertical base 2450L. See also the description of Figure 24 above.

[0211] Figure 41B is a top view 4150 of the intermediate structure 4100 shown in Figure 41A. The "shortened" base separation hard mask 2350 allows the removal of the extrinsic vertical base 2450 material to expose the front end 1650F and back end 1650B of the vertical base 1650. By allowing the front end 1650F and back end 1650B of the vertical base 1650 to protrude beyond the extrinsic vertical base 2450, the extrinsic vertical base 2450 is physically separated by the vertical base 1650 to the left 2450L and right 2450R sides. This allows embodiments of the Darlington pair BJT sensor (vertical / sensing BJT) to have dual bases. In some embodiments, one of the bases is used as a sensing base, such as the base connected to a metal sliver sensing surface 3650, for example, 2450R. For example, the other or non-sensing base or control base, such as a base (e.g., 2450L) that is not connected to the metal sliver sensing surface 3650, may be used as a separate control base.

[0212] Figure 42A is a cross-sectional view showing the intermediate structure 4200 after filling with interlayer dielectric (ILD) 2550.

[0213] Figure 42B is a top view 4250 of the intermediate structure 4200 shown in Figure 42A.

[0214] Please also refer to the explanation of ILD filling in Figure 25.

[0215] Figure 43 is a flowchart of process 4300 for creating the Darlington pair BJT sensor 3700.

[0216] Step 4310 initiates process 4300 by creating a horizontal / lateral / amplified BJT652 / 550 / 654 having a common exogenous base / collector 350, as described in the descriptions of Figures 1 to 9.

[0217] Step 4320 creates a vertical / sensing BJT 2950 / 1650 / 350 / 2450 having a dual extrinsic base 2450 / 2450L / 2450R and a common extrinsic base / collector 350 which is an extrinsic base 350 for the lateral BJT and a vertical collector 350 for the vertical / sensing BJT.

[0218] Step 4330 creates the sensing trenches 3625 / 3250 and the metal sliver sensing surface 3650, as described in the descriptions of Figures 32 to 36.

[0219] Step 4340 creates external connections 3150 / 3754 / 3756 / 3758 and external configuration connections, as described in the explanation in Figure 37.

[0220] Figure 44 is a schematic diagram of a non-limiting example of a dual-base, complementary (Sicley) Darlington pair BJT sensor 4400, where the vertical / sensing BJT 4425 is a PNP BJT with two bases (control base, external connection 3754, and sensing base, connection 3650), and the horizontal / lateral / amplifying BJT 4475 is an NPN BJT.

[0221] As mentioned above, various BJT polarities and configurations are conceivable.

[0222] The vertical / sensing BJT4425 has a vertical emitter 2950 with an external connection 3756. The vertical collector 350 is the exact same element as the extrinsic base 350 which is in contact with the horizontal base 550 of the horizontal / amplifying BJT4475 / 652 / 550 / 654 / 350, shown as a common internal connection in Figure 44. The vertical / sensing BJT4425 has a separate intrinsic base 2450 / 2450L / 2450R, where the control base, 2450L as one example, is connected to the external connection 3754. The metal sliver sensing surface 3650 is the sensing base 3650, connected to the right side 2450R (as one example) of the extrinsic vertical base 2450. In some embodiments, the emitter of the vertical / sensing BJT4425 is externally connected / configured to the collector of the horizontal / amplifying BJT4475 to complete the configuration of the Darlington pair sensor 3700 / 4400. Other external connections / configurations are conceivable to enable various configurations of the Darlington pair sensor.

[0223] Other polarities of the vertical sensing BJT4425 and horizontal / amplifying BJT4475 are conceivable. For example, a complementary (Siclay) Darlington pair can be constructed in which the vertical sensing BJT4425 is an NPN BJT and the horizontal / amplifying BJT4475 is a PNP BJT.

[0224] The descriptions of various embodiments of the present invention are presented for illustrative purposes only and are not intended to be exhaustive or limiting to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope of the described embodiments. For example, the semiconductor devices, structures, and methods disclosed in the embodiments of the present invention may be used in applications, hardware, and / or electronic systems. Suitable hardware and systems for implementing embodiments of the present invention may include, but are not limited to, personal computers, communication networks, e-commerce systems, portable communication devices (e.g., mobile phones and smartphones), solid-state media storage devices, expert systems and artificial intelligence systems, and functional circuits. Systems and hardware incorporating semiconductor devices constitute the intended embodiments of the present invention.

[0225] The terms used herein have been selected to describe the principles and practical applications of the embodiments or to describe technical improvements to technologies found in the market, or to enable other persons skilled in the art to understand the embodiments disclosed herein in a different manner. Devices, components, elements, features, apparatus, systems, structures, techniques, and methods described using various terms, which perform substantially the same function, operate substantially the same way, have substantially the same applications, and / or perform similar steps, are contemplated as embodiments of the present invention.

Claims

1. It is a Darlington pair sensor, An amplifying bipolar junction transistor (BJT) is arranged horizontally on a substrate, the amplifying BJT having a horizontal emitter, a horizontal base, a horizontal collector, and a common exogenous base / collector, the common exogenous base / collector being the amplifying BJT exogenous base for the amplifying BJT, and the common exogenous base / collector being in contact with and positioned on the horizontal base; A sensing BJT oriented vertically to the amplification BJT, the sensing BJT having a vertical emitter, a vertical base, an exogenous vertical base separated into a left exogenous vertical base and a right exogenous vertical base, and a common exogenous base / collector, the common exogenous base / collector also serving as a sensing BJT collector for the sensing BJT. Equipped with, Here, the left exogenous vertical base is in contact with the left side of the vertical base, the right exogenous vertical base is in contact with the right side of the vertical base, and the left exogenous vertical base and the right exogenous vertical base are separated from each other. Sensor.

2. The sensor according to claim 1, wherein the left exogenous vertical base and the right exogenous vertical base are separated from each other by the vertical base.

3. The sensor according to claim 1, comprising one of the following configurations: a) the amplification BJT is PNP and the sensing BJT is NPN, and b) the amplification BJT is NPN and the sensing BJT is PNP.

4. A sensing trench is a spatial void capable of receiving a fluid containing one or more substances to be sensed, the sensing trench is adjacent to one of the left exogenous vertical base and the right exogenous vertical base which is a sensing exogenous vertical base, and the left exogenous vertical base and the right exogenous vertical base which are not the sensing exogenous vertical base are control exogenous vertical bases; and A sliver sensing surface, the sliver sensing surface is a conductive material between the sensing trench and the sensing extrinsic vertical base, and the sliver sensing surface is in electrical contact with the sensing extrinsic vertical base. The sensor according to any one of claims 1 to 3, further comprising the above.

5. The sensor according to claim 4, wherein the substance to be sensed is a biological substance, and the sensor is used as a biological sensor.

6. The sensor according to claim 4, wherein the fluid is one of a liquid and a gas.

7. The sensor according to claim 4, wherein the sliver sensing surface is the sensing base of the sensing BJT, the sliver sensing surface provides a signal to the sensing extrinsic vertical base, and the signal is induced by an interaction between the sliver sensing surface material and one or more of the substances being sensed.

8. The sensor according to claim 7, wherein the interaction is one or more of an electrical and a chemical reaction.

9. The sensor according to claim 4, wherein the control-extrinsic vertical base is a control base.

10. The sensor according to claim 4, wherein the sliver sensing surface material is titanium nitride (TiN), the substance to be sensed is hydrogen ions, and the sensor is a pH sensor.

11. The sensor according to claim 4, wherein the sliver sensing surface material is silver chloride (AgCl), and the substance to be sensed is one or more DNA molecules.

12. The sensor according to claim 4, wherein the sliver sensing surface material is functionalized with thiols, and the substance to be sensed is one or more proteins.

13. The sensor according to claim 4, wherein the vertical base is a strain base.

14. The sensor according to claim 4, wherein one or more of the exogenous vertical base and the vertical emitter are made of a large-grained polycrystalline material.

15. The sensor according to claim 4, wherein the sensing trench is connected to one or more second sensing trenches of one or more second sensors, the sensing trench and the one or more second sensing trenches are in fluid communication, and as a result the sensing trench and the one or more second sensing trenches carry a common fluid flow, and one or more substances to be sensed in the common fluid flowing through the sensing trench and the one or more second sensing trenches.

16. A method for creating a Darlington pair sensor, the method being: In the step of creating a horizontal amplifier BJT by forming a horizontal emitter, a horizontal base, and a horizontal collector on a substrate, the horizontal base is located between the horizontal emitter and the horizontal collector; A step of depositing a common exogenous base / collector on the horizontal base; A step of epitaxially growing a vertically oriented base on the aforementioned common exogenous base / collector; A step of epitaxially growing an exogenous vertical base around the aforementioned vertically true base; The step of dividing the aforementioned exogenous vertical base into a right exogenous vertical base and a left exogenous vertical base; The steps include creating a sensing trench and a metal sliver sensing surface adjacent to one of the right and left exogenous vertical bases, which are sensing exogenous vertical bases, wherein the metal sliver sensing surface is electrically connected to the sensing exogenous vertical bases; and The step of depositing a vertical emitter on the vertical intrinsic base, the vertical emitter, the vertical intrinsic base, the extrinsic vertical base, and the common extrinsic base / collector constitute a vertical sensing BJT, where the common extrinsic base / collector is the collector of the vertical sensing BJT. Equipped with, Here, the common exogenous base / collector is also the exogenous base on the horizontal base of the horizontal amplifier BJT. method.

17. The method according to claim 16, wherein the step of dividing the extrinsic vertical base is performed by the vertical intrinsic base.

18. The method according to claim 16, wherein the step of dividing the extrinsic vertical base is performed by the step of exposing the front and back ends of the vertical intrinsic base.

19. The method according to any one of claims 16 to 18, further comprising the step of connecting a separate external connection to each of the horizontal emitter, the horizontal collector, a control base which is one of the right exogenous vertical base and the left exogenous vertical base, which is not the sensing exogenous vertical base, and the vertical emitter.

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