Integrated circuit device with thin-film resistor using positive and negative temperature coefficients of resistance and methods of forming the same

Abstract

This disclosure relates to an integrated circuit (IC) device comprising a thin-film resistor (TFR) overlaid on a substrate, and comprising a first thin film and a second thin film stacked in a direction transverse to the top surface of the substrate. The first thin film comprises a first material having a negative temperature resistivity (TCR) over a temperature range. The negative TCR causes the resistance of the first thin film to decrease as the temperature of the first thin film increases. The second thin film comprises a second material having a positive TCR over a temperature range. The positive TCR causes the resistance of the second thin film to increase as the temperature of the second thin film increases.

Description

Technical Field

[0001] This disclosure relates to a thin-film resistive integrated circuit device using positive and negative resistance temperature coefficients and a method for forming the same. Prior Technology

[0002] Thin-film technology has been applied to many different types of components in integrated circuit (IC) environments. These components include transistors, capacitors, resistors, inductors, etc. For example, thin-film resistors are particularly important in low-resistivity, low-temperature applications (such as haptic actuators, wearable devices, etc.). Therefore, at such low resistivity values, an important characteristic of thin-film resistors may be to provide a stable resistance value over the required temperature range. Summary of the Invention

[0003] This disclosure relates to an integrated circuit (IC) device, comprising: a thin-film resistor (TFR) covered on a substrate, the thin-film resistor comprising a first thin film and a second thin film, the first thin film and the second thin film being stacked in a transverse direction along the top surface of the substrate, wherein the first thin film comprises a first material having a negative temperature coefficient of resistance (TCR) over a temperature range, the negative temperature coefficient of resistance causing the resistance of the first thin film to decrease as the temperature of the first thin film increases; and the second thin film comprises a second material having a positive temperature coefficient of resistance (TCR) over a temperature range, the positive temperature coefficient of resistance causing the resistance of the second thin film to increase as the temperature of the second thin film increases.

[0004] This disclosure also relates to an integrated circuit (IC) device, comprising: a thin-film resistor (TFR) disposed within an interlayer dielectric (ILD) layer and on a barrier layer on a substrate, the TFR comprising a plurality of thin films stacked in a direction extending away from the substrate, the plurality of thin films comprising: a first material comprising a metal nitride, and a second material comprising a metal, the second material being entirely above or below the first material; a first conductive interconnect disposed on the TFR; and a second conductive interconnect disposed on the TFR and laterally separated from the first conductive interconnect.

[0005] This disclosure also relates to a method of forming an integrated circuit device, comprising: forming a first thin film on a substrate composed of one of a first material or a second material; forming a second thin film on the first thin film composed of another of the first material or the second material; and etching the first thin film and the second thin film to form at least a portion of a thin film resistor (TFR) comprising the first material and the second material, wherein the first material has a negative temperature coefficient (TCR) over a temperature range, the negative temperature coefficient causing the resistance of the first material to decrease as the temperature of the first material increases, and the second material has a positive TCR over a temperature range, the positive TCR causing the resistance of the second material to increase as the temperature of the second material increases. Simple Explanation of the Diagram

[0006] A better understanding of the various aspects of this disclosure can be achieved by referring to the accompanying drawings and the detailed description below. It should be noted that, according to industry standard practice, the features are not drawn to scale. In fact, for ease of discussion, the dimensions of the features may be arbitrarily increased or decreased.

[0007] Figures 1A to 1D illustrate schematic cross-sectional views of some embodiments of thin-film resistor (TFR) structures of integrated circuit (IC) devices employing positive resistivity (TCR) and negative TCR materials in accordance with the present disclosure.

[0008] Figure 2 illustrates a conceptual diagram of the sheet resistance versus temperature in relation to certain embodiments of an IC device employing a TFR structure with materials having positive TCR and materials having negative TCR, according to the present disclosure.

[0009] Figure 3 illustrates a cross-sectional view of some embodiments of an integrated circuit device employing a TFR structure having positive TCR material and negative TCR material, according to the present disclosure.

[0010] Figures 4A to 4D show cross-sectional views of some embodiments of the integrated circuit device associated with the TFR structure of Figures 1A to 1D, according to the present disclosure.

[0011] Figures 5A to 5K show cross-sectional views of some embodiments of an integrated circuit device employing the TFR structure shown in Figures 1C and 4C at different manufacturing stages, in accordance with this disclosure.

[0012] Figure 6 shows a block diagram of some embodiments of an integrated circuit device formation method employing a TFR structure according to the present disclosure.

[0013] Figures 7A and 7B are schematic diagrams of the first and second materials, respectively, for forming the TFR structure of the integrated circuit device according to the present disclosure. Implementation

[0014] This disclosure provides numerous different implementations or embodiments for achieving the various features of this disclosure. Specific examples of components and arrangements are described below to simplify the content of this disclosure. Of course, these are merely examples and are not intended to be limiting. For example, in the following description, the formation of a first feature on or above a second feature may include embodiments where the first and second features are in direct contact, or embodiments where an additional feature is formed between the first and second features, such that the first and second features do not need to be in direct contact. Furthermore, reference numerals and / or letters may be repeated in various embodiments of this disclosure. Such repetition is for simplicity and clarity and does not in itself determine the relationship between the various embodiments and / or configurations discussed.

[0015] Furthermore, for ease of description, this document uses spatial relative terms such as "below," "below," "lower part," "upper part," and "upper part" to describe the relationship between one element or feature and another element or feature shown in the figure. In addition to the orientations described in the figure, spatial relative terms also include different orientations of the device during use or operation. The device may also be in other orientations (rotated 90 degrees or other orientations), and the spatial relative descriptors used here will be interpreted accordingly.

[0016] The "resistivity" or ability of a material to resist electric current is sometimes expressed as volume resistivity, denoted by ρ, and measured in ohm-meters (Ω-m) or ohm-cm (Ω-cm). Using this volume resistivity value, the resistance R (in ohms (Ω) of a particular material sample can be determined using the relationship R = ρ(L / A) = ρ(L / Wt), which represents the cross-sectional area A through which current can flow (e.g., a rectangular region of width W and thickness t) and the length L through which current can flow.

[0017] For thin-film resistors (sometimes referred to here as TFRs), the uniform thickness t of the resistor is significantly smaller than the width W and length L of the TFR. Sometimes, different resistivity measurement methods (called "sheet resistance" or "surface resistance," denoted by Rs, in ohms per square (Ω / □)) are used to represent the TFR. Furthermore, if the thickness t of the TFR is known, the volume resistivity of the TFR can be calculated from the sheet resistance Rs using the relationship ρ = Rs × t. Additionally, the resistance R of the TFR is R = (ρ / t)(L / W) = Rs(L / W), where the length L and width W are two dimensions in the planar view of the TFR.

[0018] Assuming the proper functioning of a circuit employing a TFR depends on the stable resistance R of the TFR over a relevant temperature range, and that resistance R depends on the sheet resistance Rs, then the stable value of the sheet resistance Rs over the same temperature range would likely be ideal. Unfortunately, such stability of the sheet resistance Rs can be difficult to achieve in thin-film environments, including at low temperatures (e.g., greater than or equal to -40 degrees Celsius). More specifically, the stable resistance over a given temperature range depends on a low "temperature coefficient of resistance" (TCR) within that range. TCR, sometimes denoted by α, is a value that can vary with temperature, indicating the rate of change of resistance or resistivity relative to temperature.

[0019] To address these issues, this disclosure provides embodiments of integrated circuit devices employing a thin-film resistor (TFR) structure comprising at least two thin films containing two different materials. In some embodiments, the first material may have a negative TCR over a specific temperature range, while the second material may have a positive TCR over the same temperature range. Therefore, in some embodiments, current can flow parallel to the first and second materials (e.g., in a direction orthogonal to the thickness of the TFR structure), thereby producing a combined TCR for the TFR structure within the same temperature range that is between the positive and negative TCRs of the first and second materials (e.g., a combined TCR closer to zero than either the first or second material's TCR). For example, the overall or combined TCR of a TFR structure comprising at least two thin films can maintain a low (e.g., near-zero) TCR value (e.g., below about 50 parts per million (ppm / °C)) over a temperature range (e.g., from about -40°C to about +125°C). Therefore, using such a TFR structure (embodiments thereof will be discussed in more detail below) can provide stable sheet resistance Rs and associated resistance Rs over the desired temperature range, thereby facilitating the ideal operation of a variety of circuits and devices. Such circuits and devices may include, but are not limited to, haptic actuators and wearable devices, as well as digital-to-analog converters in medical devices, audio applications, and precision control and instrumentation.

[0020] Figures 1A to 1D respectively show schematic diagrams of some embodiments of TFR structures 100A to 100D (more generally, TFR structure 100). According to this disclosure, the integrated circuit (IC) device employs one or more thin films of negative thermal resistivity (TCR) material 102 and one or more thin films of positive TCR material 104 within a specific temperature range. The resistance of the negative TCR material 102 decreases with increasing temperature of the one or more thin films (such as negative TCR material), while the resistance of the positive TCR material 104 increases with increasing temperature of the one or more thin films (such as positive TCR material).

[0021] In some embodiments, the negative TCR material 102 and the positive TCR material 104 comprise conductive thin films. In some embodiments, the negative TCR material 102 may comprise a nitride substrate material (e.g., a metal nitride, such as tantalum nitride (TaN, or more generally TaNx), titanium nitride (TiN), or similar materials), while the positive TCR material 104 may comprise a metal (e.g., tantalum (Ta), titanium (Ti), or similar materials), such as the associated metal of the nitride substrate material of the negative TCR material 102.

[0022] In Figures 1A through 1D, contact regions 101 (e.g., electrodes for electrically coupling the TFR structure 100 to other components of the integrated circuit arrangement) are typically marked at or near opposite ends of the TFR structure 100. In some embodiments, the contact regions may be located on the upper or lower surface of the TFR structure 100, at any location of the negative TCR material 102 and the positive TCR material 104, at the end of any location of the negative TCR material 102 and the positive TCR material 104, etc. Therefore, in some embodiments, during operation, current can be understood to flow between the contact regions 101 (e.g., between the left and right ends of the TFR structure 100 as seen by the reader).

[0023] Furthermore, although the films including the negative TCR material 102 and the positive TCR material 104 are depicted as being laid on top of each other and thus in contact with each other in Figures 1A to 1D, other embodiments may also be adopted, such as the films being placed side by side, in contact with each other, or separated from each other, but these will not be explicitly discussed here to simplify the discussion below.

[0024] Due to the relationship between and / or the coupling between the thin films, the thin film containing the negative TCR material 102 is electrically coupled in parallel with the thin film containing the positive TCR material 104. Therefore, the individual resistances of the thin films are connected in parallel, resulting in a combined resistance that is lower than that of the individual resistances.

[0025] Furthermore, in Figures 1A to 1D, the thicknesses of the negative TCR material 102 film and the positive TCR material 104 film are different. In some embodiments, the relative thicknesses of the negative TCR material 102 and the positive TCR material 104 may affect the combined TCR of the TFR structure 100, thereby affecting the overall change in sheet resistance Rs. More specifically, in some embodiments, a specific ratio of the total thickness of the negative TCR material 102 film to the total thickness of the positive TCR material 104 film can produce minimal change in sheet resistance Rs within the desired temperature range. More specifically, in some embodiments, to balance the relatively high TCR amplitude of the positive TCR material 104 with the relatively low TCR amplitude of the negative TCR material 102, a correspondingly thicker negative TCR material 102 relative to the positive TCR material 104 can be used to minimize the combined TCR. Similarly, to balance the relatively high TCR magnitude of the negative TCR material 102 with the relatively low TCR magnitude of the positive TCR material 104, a correspondingly thicker positive TCR material 104 relative to the negative TCR material 102 can be used to minimize the combined TCR. In some embodiments, the ratio of the total thickness of the negative TCR material 102 film to the total thickness of the positive TCR material 104 film can be initially approximated using a theoretical value of the ratio of the TCR (e.g., average TCR) of the positive TCR material 104 to the TCR (e.g., average TCR) of the negative TCR material 102. In some embodiments, strictly applying this theoretical ratio may not yield a minimized combined TCR (e.g., due to variations in the composition and structure of the negative TCR material 102 and positive TCR material layers that may occur during and / or after manufacturing). In some embodiments, the theoretical ratio can be within 20% of the actual thickness ratio, thereby minimizing the combined TCR of the TFR structure 100. Subsequently, empirical testing can be performed on actual manufactured examples of the TFR structure 100 using various thickness ratios to determine the minimized combined TCR.

[0026] Furthermore, in some embodiments, the overall sheet resistance Rs of the TFR structure 100 can be changed by altering the thicknesses of the negative TCR material 102 and the positive TCR material 104 (e.g., while maintaining the desired thickness ratio). More specifically, increasing the thickness reduces the overall sheet resistance Rs of the TFR structure 100, while decreasing the thickness increases the overall sheet resistance Rs of the TFR structure 100.

[0027] In some embodiments, assuming the positive TCR material 104 is tantalum (Ta) and the negative TCR material 102 is tantalum nitride (TaN), the ratio of the total film thickness of the positive TCR material 104 to the total film thickness of the negative TCR material 102 can be between about 0.11 and about 0.22. For example, the total thickness of the positive TCR material 104 film can be between about 50 angstroms and about 150 angstroms, while the total thickness of the negative TCR material 102 film can be between about 1100 angstroms and about 1400 angstroms. Such a ratio range allows the combined TCR of the TFR structure 100 to be less than about 50 ppm / °C over a temperature range of at least from about -40 to about +125°C. More specifically, in some embodiments, the ratio of the total thickness of the tantalum (Ta) film to the total thickness of the tantalum nitride (TaN) film can be between about 0.10 and about 0.20, about 0.16, or other similar values. In some embodiments, using such a ratio can produce a combined TCR of less than about 5.7 ppm / °C.

[0028] Furthermore, in some embodiments, the negative TCR material 102 (such as the nitride-based material mentioned above) can provide a range of nitrogen concentrations and / or crystal structures to promote consistent and acceptable negative TCR and low overall sheet resistance Rs. For example, in the case of tantalum nitride (TaN), the percentage of nitrogen (N) ranges from 29% to 32%, and the percentage of tantalum (Ta) ranges from 67% to 69%, resulting in an N / Ta ratio of approximately 0.43 to approximately 0.46. This concentration can be confirmed by methods such as X-ray photoelectron spectroscopy (XPS) analysis. In some embodiments, a higher nitrogen content in tantalum nitride may increase the TCR value of the negative TCR material 102, but may also increase the amount of nitrogen diffusion from tantalum nitride to tantalum in the positive TCR material 104, thereby altering the properties of the positive TCR material 104.

[0029] Furthermore, in some embodiments, the tantalum nitride (TaN) used as the negative TCR material 102 preferably has a (110) hexagonal orientation structure, as specified by the Miller index nomenclature, which can be confirmed by X-ray diffraction (XRD) analysis. More specifically, this hexagonal structure produces a relatively low volume resistivity of about 154 microohm-cm (µΩ-cm), which may be more suitable for low-resistivity applications compared to the higher resistivity of the body-centered cubic (BCC) (200) structure with 280-480 µΩ-cm.

[0030] Figure 1A is a schematic cross-sectional view of a TFR structure 100A, which includes a first film and a second film. The first film contains a positive TCR material 104 within a certain temperature range, while the second film is disposed above the first film (e.g., on top) and contains a negative TCR material 102 within the same temperature range. In some embodiments, the thickness of the negative TCR material 102 (in the vertical direction as shown in Figure 1A) is significantly greater than the thickness of the positive TCR material 104. As mentioned above, this thickness ratio can determine the amount of change in sheet resistance Rs within the desired temperature range. Therefore, the selected ratio (e.g., approximated by the theoretical ratio described above, and possibly refined experimentally) can produce the minimum desired level of change in sheet resistance Rs within the temperature range. Furthermore, in some embodiments, the negative TCR material 102 of the second film can serve as a protective barrier against oxidation and / or nitriding of the underlying first film during the fabrication of an integrated circuit device employing the TFR structure 100A.

[0031] Figure 1B is a schematic cross-sectional view of a TFR structure 100B, which includes a first film (containing a negative TCR material 102) and a second film (containing a positive TCR material 104), the second film being disposed above (e.g., on top of) the first film. In some embodiments, the thickness of the negative TCR material 102 is significantly greater than the thickness of the positive TCR material 104, and can have the same ratio as in Figure 1A, which can produce the desired minimum sheet resistance Rs variation level within the desired temperature range. Furthermore, in some embodiments, the negative TCR material 102 as the first film can provide adhesion between the TFR structure 100B and the dielectric layer, the TFR structure 100B being located above the dielectric layer.

[0032] Figure 1C is a schematic cross-sectional view of a TFR structure 100C, which includes a first film containing a negative TCR material 102; a second film disposed above (e.g., on top) the first film containing a positive TCR material 104; and a third film disposed above (e.g., on top) the second film containing a negative TCR material 102. In some embodiments, the total thickness of the negative TCR material 102 in the first and third films is significantly greater than the thickness of the positive TCR material 104 in the second film. Furthermore, in some embodiments, this ratio may be the same as that in Figures 1A and 1B, which may minimize the variation level of the sheet resistance Rs over certain temperature ranges. Furthermore, in some embodiments, the negative TCR material 102 of the third film may serve as a protective barrier against oxidation and / or nitriding of the underlying second film during the fabrication of the integrated circuit device in which the TFR structure 100C is located. Furthermore, in some embodiments, the negative TCR material 102 of the first film may provide adhesion between the TFR structure 100C and the dielectric layer in which the TFR structure 100C is located.

[0033] Figure 1D is a schematic cross-sectional view of a TFR structure 100D, which includes a first film containing a positive TCR material 104; a second film disposed above (e.g., on top of) the first film and containing a negative TCR material 102; and a third film disposed above (e.g., on top of) the second film and containing the positive TCR material 104. In some embodiments, the thickness of the negative TCR material 102 in the second film is significantly greater than the total thickness of the positive TCR material 104 in the first and third films. Furthermore, in some embodiments, this ratio may be the same as that in Figures 1A, 1B, and 1C, which may minimize the variation level of the sheet resistance Rs over the relevant temperature range.

[0034] Although two-layer films are shown in Figures 1A and 1B, and three-layer films are shown in Figures 1C and 1D, four or more films can be stacked together in a TFR structure, where the films alternate between negative TCR material 102 and positive TCR material 104. In some embodiments, the ratio of the total thickness of the negative TCR material 102 film to the total thickness of the positive TCR material 104 film can determine the combined TCR of the TFR structure, which can minimize the variation of the sheet resistance Rs over the relevant temperature range.

[0035] Figure 2 illustrates conceptual diagrams 200A, 200B, and 200C showing the variation of sheet resistance Rs with temperature T. These diagrams relate to some embodiments of integrated circuit devices employing a TFR structure 100 having a positive TCR material 104 and a negative TCR material 102, according to this disclosure. More specifically, Figures 200A, 200B, and 200C respectively depict the relationship between sheet resistance Rs of the positive TCR material 104, the negative TCR material 102, and the TFR structure 100 and temperature T in the temperature range T1 to T2.

[0036] For example, in Figure 200A, the sheet resistance Rs of the positive TCR material 104 increases continuously over the temperature range, while in Figure 200B, the sheet resistance Rs of the negative TCR material 102 decreases continuously over the same temperature range. Therefore, in some embodiments, the slope of each point along the lines in Figures 200A and 200B reflects the TCR of the relevant materials at a specific temperature T at that point. Thus, as shown in Figures 200A and 200B, the TCR of the positive TCR material 104 and the TCR of the negative TCR material 102 may vary slightly over the relevant temperature range, remaining either positive or negative. As shown in Figures 200A and 200B, Figures 200A and 200B are slightly curved rather than strictly linear. Considering the significant difference in the positive TCR value of the positive TCR material 104 reacting in Figure 200A compared to the negative TCR value of the negative TCR material 102 reacting in Figure 200B, the total thickness of the negative TCR material 102 may need to be greater than the total thickness of the positive TCR material 104, based on the TCR values ​​reacted in Figures 200A and 200B, to produce the combined TCR of the TFR structure 100. The positive TCR value of the positive TCR material 104 balances the negative TCR value of the negative TCR material, thereby making the absolute value of the combined TCR of the TFR structure 100 smaller than (e.g., closer to zero than the absolute values ​​of either the positive TCR material 104 or the negative TCR material 102), as shown in Figure 200C, which shows the nearly flat level of the sheet resistance Rs of the TFR structure 100 in the temperature range T1 to T2. In some embodiments, the combined TCR of the TFR structure 100 is almost zero. Such ratios (e.g., theoretical ratios based on TCR value ratios, which may be altered experimentally, as described above) are depicted in Figures 1A to 1D, as discussed in detail above. In other embodiments, if the TCR value of the positive TCR material 104 is less than the TCR value of the negative TCR material 102 within the same temperature range, the total thickness of the positive TCR material 104 may be greater than the total thickness of the negative TCR material 102 to provide the TFR structure 100 with a TCR of almost zero within the temperature range.

[0037] Figure 3 shows a cross-sectional view of some embodiments of an integrated circuit device 300 employing a TFR structure 100 with a positive TCR material 104 and a negative TCR material 102, according to this disclosure. As shown, the integrated circuit device 300 may include a substrate 302 (e.g., a silicon substrate) that may include multiple doped or implanted regions 304 (e.g., n-doped regions) that can serve as source-drain regions of a transistor. Located on the substrate 302 may be one or more gate structures 306 and overlay contacts 308 within a dielectric layer 314 (e.g., an interlayer dielectric (ILD) layer). Structures 310 (e.g., forming a metal layer) and associated vias 312 may be further disposed within the dielectric layer 314, some of which may be connected to the doped regions 304. The dielectric layer 314 may contain one or more dielectric materials, including but not limited to silicon oxide (SiO x) (such as silicon nitride (SiN), silicon carbide (SiC), carbon-doped silicon dioxide, silicon oxynitride, borosilicate glass (BSG), phosphosilicone glass (PSG), borosilicate phosphosilicone (BPSG), fluorosilicone glass (FSG), undoped silicate glass (USG), porous dielectric materials, or similar materials).

[0038] An etch stop layer 316 may be disposed on the dielectric layer 314. The etch stop layer 316 may comprise, but is not limited to, silicon nitride (SiN), silicon carbide (SiC), or silicon carbide (SiCN). In some embodiments, as shown in FIG3, one or more additional conductive structures 310 or associated vias 312 within the additional dielectric layer 314 and one or more additional etch stop layers 316 may be disposed above the etch stop layer 316. Such structures, as well as the TFR structure 100 described below, may appear during the back-end (BEOL) process of the integrated circuit device 300. In some embodiments, a barrier layer 318 (e.g., silicon carbide (SiC) to provide a high breakdown voltage and / or temperature barrier layer) may be placed on the substrate 302 and the subsequent dielectric layer 314 prior to the deposition of the material associated with the TFR structure 100.

[0039] In some embodiments, the top or upper part of the barrier layer 318 may be an oxide layer 320 (e.g., silicon dioxide (SiO2) or other dielectric material) serving as a non-conductive substrate for the TFR structure 100 disposed thereon. As described above with respect to Figures 1A to 1D, the TFR structure 100 may comprise two or more thin films of negative TCR material 102 (e.g., tantalum nitride (TaN), titanium nitride (TiN), etc.) and positive TCR material 104 (e.g., tantalum (Ta), titanium nitride (Ti), etc.).

[0040] Furthermore, in some embodiments, an insulating film 322 (e.g., a nitride-based film, such as silicon nitride (SiN), aluminum nitride (AlN), silicon carbide (SiC), or similar materials) may be disposed on top of the TFR structure 100 to electrically isolate the TFR structure 100 and / or protect the TFR structure 100 from environmental factors during the fabrication of the integrated circuit device 300. In some embodiments, the thickness of the insulating film 322 is at least 200 Å.

[0041] Contacts or through-holes 312 that are electrically connected to the TFR structure 100 (e.g., through the insulating film 322) can serve as electrodes or terminals of the TFR structure 100, allowing current to pass through. In some embodiments, as shown in FIG3, electrodes in the form of through-holes 312 may pass through the insulating film 322 and extend through the upper surface of the TFR structure 100. In some embodiments, electrodes may extend to the upper surface of the TFR structure 100 and / or contact a side end of the TFR structure 100.

[0042] Furthermore, in some embodiments, the oxide layer 320, TFR structure 100, insulating film 322, and via 312 may be located in another dielectric layer 314. Additionally, in some embodiments, additional vias (such as through-dielectric vias (TDV) 311) may extend through the upper surface of the integrated circuit device 300 and connect to the via 312, which serves as an electrode of the TFR structure 100. Furthermore, in some embodiments, in addition to the metallization layers described in FIG. 3, the integrated circuit device 300 may also include other metallization layers processed by BEOL. Furthermore, multiple TFR structures 100 may be included in one or more such metallization layers.

[0043] Figures 4A to 4D show cross-sectional views of some embodiments of integrated circuit devices 300A to 300D associated with the TFR structures 100A to 100D of Figures 1A to 1D, respectively, according to this disclosure. Apart from the differences in the TFR structures 100A to 100D, the remaining portions of the integrated circuit devices 300A to 300D are identical to those described above in conjunction with Figure 3.

[0044] More specifically, Figure 4A shows a cross-sectional view of an integrated circuit device 300A, which includes a TFR structure 100A as described in Figure 1A above, wherein a first layer of positive TCR material 104 is located below a second layer of negative TCR material 102.

[0045] Figure 4B shows a cross-sectional view of an integrated circuit device 300B, which includes a TFR structure 100B, as described above in conjunction with Figure 1B, wherein a first layer of negative TCR material 102 is located below a second layer of positive TCR material 104.

[0046] Figure 4C shows a cross-sectional view of an integrated circuit device 300C, which includes a TFR structure 100C, as described above with respect to Figure 1C, wherein a first layer of negative TCR material 102 is located below a second layer of positive TCR material 104, and the second layer of positive TCR material 104 is located below a third layer of negative TCR material 102.

[0047] Figure 4D shows a cross-sectional view of an integrated circuit device 300D, which includes a TFR structure 100D, as described above in conjunction with Figure 1D, wherein a first layer of positive TCR material 104 is located below a second layer of negative TCR material 102, and the second layer of negative TCR material 102 is located below a third layer of positive TCR material 104.

[0048] In each integrated circuit device 300A to 300D, the ratio of the total thickness of the negative TCR material 102 film to the total thickness of the positive TCR material 104 film determines the amount of variation of the sheet resistance Rs within the desired temperature range. Therefore, a specific ratio can be selected to minimize this variation, thereby stabilizing the sheet resistance Rs and the associated resistance of the TFR structures 100A to 100D within the relevant temperature range.

[0049] Figures 5A to 5K show cross-sectional views of some embodiments of integrated circuit devices (e.g., integrated circuit device 300C of Figure 4C) employing TFR structures (e.g., TFR structure 100C of Figures 1C and 4C) at different stages of manufacturing according to this disclosure. While Figures 5A to 5K are described as a series of actions, it is understood that these actions are not limiting, as the order of actions in each series may change in other embodiments, and the disclosed methods are applicable to other structures. In other embodiments, certain actions illustrated and / or described may be omitted in whole or in part.

[0050] For example, Figure 5A illustrates a substrate 302 in which a doped region 304 is formed. Furthermore, a dielectric layer 314 is formed on top of the substrate 302, in which conductive structures 310 and interconnect vias 312, as well as gate structures 306 and associated conductive contacts 308, are formed. In some embodiments, the substrate 302 may be a p-type substrate, and the doped region 304 may be an n-type doped region. In some embodiments, the continuous dielectric layer 314 may be separated by an etch stop layer 316 or a barrier layer 318 to protect the upper surface of the underlying dielectric layer 314. In some embodiments, the structure described in Figure 5A can serve as an example of a starting substrate on which thin film processing can be initiated to create a TFR structure (e.g., TFR structure 100C in Figures 1C and 4C).

[0051] Figure 5B illustrates the formation process of oxide layer 320 (e.g., silicon dioxide (SiO2) or other dielectric materials) (e.g., sputtering, evaporation, chemical vapor deposition (CVD) or other forms of thin film deposition), which can be used as a non-conductive substrate for the TFR structure 100C formed thereon.

[0052] Figures 5C to 5E illustrate the formation (e.g., deposition, such as through sputtering, evaporation, CVD, or other forms of thin film deposition) of the first, second, and third thin films of the TFR structure 100C (as shown in Figure 4C). More specifically, as shown in Figure 5C, a first thin film of negative TCR material 102 is formed on the oxide layer 320. Then, a second thin film of positive TCR material 104 is formed on the first thin film, as shown in Figure 5D. Then, in Figure 5E, a third thin film of negative TCR material 102 is formed on the second thin film. In other embodiments, other forms of TFR structures besides TFR structure 100C, such as TFR structures 100A, 100B, or 100D, can be formed on the oxide layer 320.

[0053] Figure 5F illustrates the formation of an insulating film 322 (e.g., a nitride-based film, such as silicon nitride (SiN), aluminum nitride (AlN), silicon carbide (SiC), etc.) on a third thin film (e.g., deposition, such as through sputtering, evaporation, CVD or other forms of thin film deposition).

[0054] Figure 5G illustrates the removal (e.g., etching) of oxide layer 320, a first thin film of negative TCR material 102, a second thin film of positive TCR material 104, a third thin film of negative TCR material 102, and a portion of insulating film 322 to form TFR structure 100C, and non-conductive layers above and below TFR structure 100C. In some embodiments, other thin film structures, such as other TFR structures, may be etched simultaneously.

[0055] Figure 5H illustrates the formation (e.g., deposition) of an additional dielectric layer 314 covering the portion of the TFR structure 100 and the area surrounding the barrier layer 318.

[0056] Figure 5I illustrates vias 312 formed (e.g., etched or trenched and subsequently deposited) in an additional dielectric layer 314, including vias 312 serving as electrodes of the TFR structure 100C. In some embodiments, the etching or trenching of the vias 312 serving as electrodes may penetrate through the insulating film 322 and extend to (or through) the upper surface of the third thin film of the negative TCR material 102. In other embodiments, the electrodes may further extend into the TFR structure 100C, including extending to and through the upper surface of the oxide layer 320.

[0057] Figure 5J illustrates another etch barrier layer 316, another dielectric layer 314, and another etch barrier layer 316 formed (e.g., deposited) in sequence.

[0058] Figure 5K illustrates the formation (e.g., trenches and subsequent deposition) of vias (e.g., TDVs 311) such that TDVs 311 extend from the upper surface of etch stop layer 316, through etch stop layer 316, further dielectric layer 314, additional etch stop layer 316 and dielectric layer 314, and form vias 312 thereunder, including vias 312 that have electrical contact with TFR structure 100C. Therefore, in some embodiments, TFR structure 100C can be a component of a larger circuit accessible from the upper surface of integrated circuit device 300C.

[0059] Figure 6 illustrates block diagrams of some embodiments of a method 600 for forming an IC device (e.g., IC device 300C of Figure 3C) comprising a TFR structure (e.g., TFR structure 100A, 100B, 100C, or 100D) according to this disclosure. Although this method and other methods illustrated and / or described herein are illustrated as a series of actions or events, it is to be understood that this disclosure is not limited to the illustrated sequence or actions. Therefore, in some embodiments, actions may be performed in a different order than illustrated, and / or may be performed simultaneously. Furthermore, in some embodiments, the illustrated actions or events may be subdivided into multiple actions or events that may be performed at different times or simultaneously with other actions or sub-actions. In some embodiments, certain illustrated actions or events may be omitted, while other unillustrated actions or events may be included.

[0060] Step 602 involves forming a first thin film (e.g., the structure described in FIG. 5A or FIG. 5B) on the substrate, comprising one of a first material or a second material, wherein the first material has a negative TCR over a temperature range (e.g., negative TCR material 102 in FIG. 1A to 1D), and the second material has a positive TCR over a temperature range (e.g., positive TCR material 104 in FIG. 1A to 1D). FIG. 5C shows a cross-sectional view of some embodiments corresponding to step 602.

[0061] In step 604, a second film comprising either the first material or another material selected from the second material is formed on the first film. Figure 5D illustrates a cross-sectional view of some embodiments corresponding to step 604. In some embodiments, one or more films formed alternately of the first and second materials may be stacked on the second film (e.g., Figure 5E illustrates the formation of a third layer).

[0062] In step 606, the first and second films are etched to form at least a portion of the TFR structure comprising the first and second materials (e.g., TFR structures 100A, 100B, 100C, or 100D). In some embodiments where additional films are present, the etching in step 606 may also simultaneously etch the additional films to form the TFR structure as well as any non-conductive films (e.g., oxide layer 320 and insulating film 322 in FIG. 5G). FIG. 5G illustrates a cross-sectional view of some embodiments corresponding to step 606.

[0063] Figures 7A and 7B illustrate schematic diagrams of a first material (e.g., negative TCR material 102) having a negative TCR over a temperature range and a second material (e.g., positive TCR material 104) having a positive TCR over a temperature range, respectively forming (e.g., through sputtering) a thin-film resistive structure of an integrated circuit device according to this disclosure. In Figures 7A and 7B, a processing chamber 701 may accommodate one or more substrates 702 (e.g., through a front-opening universal pod (FOUP), which can safely accommodate substrates 702 in a controlled environment for transfer between machines, processing, and / or measurement). In some embodiments, each substrate 702 may contain a portion of an IC device (e.g., as shown in Figure 5B), on which two or more alternating layers of negative TCR material 102 and positive TCR material 104 thin films may be formed (e.g., sputtered). The processing chamber 701 may also include a gas inlet 706 (e.g., controlled by a valve) to allow selected gases to flow into the processing chamber 701 to facilitate sputtering operations. Figures 7A and 7B also show a metal sputtering target 704 (e.g., containing tantalum (Ta), titanium (Ti) or other metallic materials) in the processing chamber 701.

[0064] In Figure 7A, during the sputtering operation, a reactive gas (e.g., nitrogen (N2) gas 708) can be supplied through gas inlet 706, wherein material ejected from the metal sputtering target 704 (e.g., Ta, Ti, or another metal) reacts with N2 gas 708 to sputter a negative TCR material 102 (e.g., tantalum nitride (TaN), titanium nitride (TiN), or another nitride substrate material) onto the substrate 702. For example, the sputtering operation can be performed during the methods of Figures 5A-5K to deposit the negative TCR material 102 described in Figures 5C and 5E. In some embodiments, a higher flow rate of N2 gas 708 may result in a higher nitrogen concentration in the negative TCR material 102, which may result in a higher TCR value (e.g., a more negative TCR value) for the negative TCR material 102.

[0065] In Figure 7B, an inert gas 710 (e.g., argon (Ar)) may flow into the processing chamber 701 to facilitate the sputtering of positive TCR material 104 (e.g., Ta, Ti, or other metals) from the metal sputtering target 704 onto the substrate 702. In some embodiments, this sputtering may be performed in a vacuum instead of the inert gas 710. For example, the sputtering operation may be performed during the methods of Figures 5A-5K to deposit the positive TCR material 104 described in Figures 5C and 5E.

[0066] Therefore, by alternating sputtering operations between those described in Figures 7A and 7B, the aforementioned alternating negative TCR material 102 and positive TCR material 104 films can be deposited by alternately providing the presence and / or type of gas through the gas inlet 706. Furthermore, throughout the process, the same substrate 702 and metal sputtering target 704 can be retained in the processing chamber 701, thereby protecting the substrate 702 to some extent from external environmental forces. Additionally, in some embodiments, various sputtering parameters (e.g., voltage, processing time, etc.) can be controlled to produce the desired film thicknesses (e.g., to provide a minimum TCR for the produced TFR structure 100 within the desired temperature range, as discussed in detail above). Furthermore, in some embodiments where the final (topmost) film of the TFR structure 100 is negative TCR material 102, this film can help prevent nitriding of the underlying positive TCR material 104 when the substrate 702 is transferred from processing chamber 701 to another processing chamber (e.g., for subsequent deposition of insulating film 322, dielectric layer 314, or similar layers).

[0067] In some embodiments, this disclosure provides an integrated circuit device including a thin-film resistor (TFR) overlaid on a substrate, comprising a first thin film and a second thin film stacked in a transverse direction along the top surface of the substrate. The first thin film comprises a first material having a negative temperature coefficient of resistance (TCR) over a temperature range, the negative TCR causing the resistance of the first thin film to decrease with increasing temperature. The second thin film comprises a second material having a positive TCR over a temperature range, the positive TCR causing the resistance of the second thin film to increase with increasing temperature. In some embodiments, the TFR has a combined TCR closer to zero than the negative TCR and positive TCR. In some embodiments, the first material comprises tantalum nitride (TaN), the second material comprises tantalum (Ta), and the thickness ratio of the second thin film to the thickness of the first thin film is in the range of about 0.11 to about 0.22. In some embodiments, the thickness ratio of the second thin film to the thickness of the first thin film may be approximated as the ratio of the negative TCR of the first material to the positive TCR of the second material. In some embodiments, the thickness ratio of the second thin film to the thickness of the first thin film is between about 0.10 and about 0.20. In some embodiments, the integrated circuit device further includes a first electrode contacting the TFR at or near a first end of the TFR; and a second electrode contacting the TFR at or near a second end of the TFR relative to the first end of the TFR. In some embodiments, a first film covers and directly contacts a second film, and the first electrode and the second electrode directly contact the first film. In some embodiments, the first film covers and directly contacts the second film, and the first electrode and the second electrode directly contact the second film. In some embodiments, the TFR further includes a third film comprising a first material, the third film being stacked in one direction with the first film and the second film, and the second film being located in one direction between the first film and the third film. In some embodiments, the TFR further includes a third film comprising a second material, the third film being stacked in one direction with the first film and the second film, and the first film being located in one direction between the second film and the third film.

[0068] In some embodiments, this disclosure provides another integrated circuit device comprising a thin-film resistor (TFR) disposed within an interlayer dielectric (ILD) layer and a barrier layer on a substrate. The TFR comprises a plurality of thin films stacked in a direction away from the substrate, the plurality of thin films comprising a first material composed of a metal nitride and a second material composed of a metal, the second material being disposed entirely above or below the first material; a first conductive interconnect disposed on the TFR; and a second conductive interconnect disposed on the TFR and laterally spaced from the first conductive interconnect, wherein the multilayer thin films have a combined TCR closer to zero than the first TCR and the second TCR. In some embodiments, the TFR has a sheet resistance varying over a temperature range from about 12 ohms / square (Ω / □) to about 16 Ω / □. In some embodiments, the first material comprises tantalum nitride (TaN); the second material comprises tantalum (Ta). In some embodiments, the first material comprises titanium nitride (TiN); the second material comprises titanium (Ti). In some embodiments, a first material has a first temperature coefficient of resistance (TCR) over a temperature range, a second material has a second temperature coefficient of resistance (TCR) over a temperature range, and the absolute value of the combined TCR of the plurality of thin films is less than the first temperature coefficient of resistance (TCR) and the second temperature coefficient of resistance (TCR). In some embodiments, the integrated circuit device further includes: an insulating film located on top of the TFR and sharing a width with the TFR, the insulating film being vertically disposed between the ILD layer and the TFR, the insulating film comprising at least one of silicon nitride (SiN), aluminum nitride (AlN), or silicon carbide (SiC).

[0069] In some embodiments, this disclosure provides a method comprising: forming a first thin film comprising one of a first material or a second material on a substrate; forming a second thin film comprising another of the first material or the second material on the first thin film; etching the first thin film and the second thin film to form at least a portion of a thin film resistance (TFR) comprising the first material and the second material, wherein the first material has a negative temperature coefficient of resistance (TCR) over a temperature range, and the second material has a positive temperature coefficient of resistance (TCR) over a temperature range. In some embodiments, forming the first thin film comprises sputtering one of the first material or the second material in a processing chamber, while forming the second thin film comprises sputtering another of the first material or the second material in a processing chamber. In some embodiments, sputtering the first material comprises sputtering a metal material toward the substrate in an atmosphere containing nitrogen (N2), and sputtering the second material comprises sputtering a metal material toward the substrate in an atmosphere containing an inert gas. In some embodiments, variations in the N2 gas flow rate alter the negative TCR of the first material.

[0070] It is understood that in this written description and the claims below, the terms "first," "second," "third," etc., are merely general identifiers used for ease of description to distinguish different elements in a figure or series of figures. These terms themselves do not imply a temporal order or structural proximity of these elements, nor are they intended to describe corresponding elements in different illustrated embodiments and / or unillustrated embodiments. For example, "first dielectric layer" associated with the first figure does not necessarily correspond to "first dielectric layer" associated with another figure, nor does it necessarily correspond to "first dielectric layer" in an unillustrated embodiment.

[0071] The features of several embodiments have been summarized above to enable those skilled in the art to better understand the various aspects of this disclosure. Those skilled in the art should understand that they can at any time design or modify other processes and structures based on the content of this disclosure to achieve the same purpose and / or attain the same advantages of the embodiments described herein. Those skilled in the art should also recognize that such equivalent structures do not depart from the spirit and scope of this disclosure, and they can make various changes, substitutions, and modifications to this document without departing from the spirit and scope of this disclosure.

[0072] 100, 100A~100D: TFR structure 101: Contact Area 102: Negative Thermal Resistivity (TCR) Materials, Negative TCR Materials 104: Positive TCR Material 200A~200C: Conceptual Diagram 300, 300A~300D: Integrated circuit devices 302:Substrate 304: Doped, implanted region, doped area 306: Gate structure 308: Overlapping contact point / conductive contact 310: Structure / Additional Conductive Structure / Conductive Structure 311: Through-Medium Via / TDV 312: Through hole 314: Dielectric layer / Additional dielectric layer / Subsequent dielectric layer 316: Etching Stop Layer / Additional Etching Stop Layer 318: Barrier Layer 320: Oxide layer 322: Insulating film 600: Method 602~606: Steps 701: Machining Room 702:Substrate 704: Metal sputtering target 706: Gas Inlet 708: Gas 710: Inert gas

Claims

1. An integrated circuit (IC) device comprising: a thin-film resistor (TFR) covering a substrate, the thin-film resistor comprising a first thin film and a second thin film, the first thin film and the second thin film being stacked along a transverse direction of a top surface of the substrate, wherein the first thin film comprises a first material having a negative temperature coefficient of resistance (TCR) over a temperature range, the negative temperature coefficient of resistance causing a decrease in the resistance of the first thin film as a temperature of the first thin film increases; and the second thin film comprising a second material having a positive temperature coefficient of resistance (TCR) over the temperature range, the positive temperature coefficient of resistance causing an increase in the resistance of the second thin film as a temperature of the second thin film increases; wherein a ratio of a thickness of the second thin film to a thickness of the first thin film is approximately equal to a ratio of the negative TCR of the first material to the positive TCR of the second material.

2. The IC device as claimed in claim 1, wherein the TFR has a combined TCR that is closer to zero than the negative TCR and the positive TCR.

3. The IC device as claimed in claim 2, wherein the first material comprises tantalum nitride (TaN), the second material comprises tantalum (Ta), and the ratio of the thickness of the second film to the thickness of the first film is in the range of about 0.11 to about 0.

22.

4. The IC device as claimed in claim 1, wherein the TFR further includes a third film, the third film comprising the first material, the third film being stacked with the first film and the second film in the direction, and the second film being located between the first film and the third film in the direction.

5. The IC device as claimed in claim 3, wherein the ratio of the thickness of the second film to the thickness of the first film is between about 0.10 and about 0.

20.

6. The IC device as claimed in claim 1 further comprises: a first electrode in contact with the TFR at or near a first end of the TFR; and a second electrode in contact with the TFR at or near a second end of the TFR opposite to the first end of the TFR.

7. The IC device as claimed in claim 6, wherein the first thin film covers and directly contacts the second thin film, and the first electrode and the second electrode directly contact the first thin film.

8. The IC device as claimed in claim 6, wherein the first thin film covers and directly contacts the second thin film, and the first electrode and the second electrode directly contact the second thin film.

9. An integrated circuit (IC) device comprising: a thin-film resistor (TFR) disposed within an inter-dielectric layer (ILD) and on a barrier layer on a substrate, the TFR comprising a plurality of thin films stacked in a direction extending away from the substrate, the plurality of thin films comprising: a first material comprising a nitride of a metal, and a second material comprising the metal, the second material being entirely above or below the first material; a first conductive interconnect disposed on the TFR; and a second conductive interconnect disposed on the TFR and laterally separated from the first conductive interconnect; wherein a ratio of a thickness of the second material to a thickness of the first material is approximately equal to a ratio of a negative temperature coefficient of resistance (TCR) of the first material to a positive temperature coefficient of resistance (TCR) of the second material.

10. A method of forming an integrated circuit device, comprising: forming a first thin film on a substrate, comprising a first material or a second material; forming a second thin film on the first thin film, comprising another material of the first material or the second material; and etching the first thin film and the second thin film to form a thin film resistor (TFR) comprising at least a portion of the first material and the second material, wherein the first material has a negative temperature coefficient (TCR) over a temperature range, the negative temperature coefficient causing a resistance of the first material to decrease as a temperature of the first material increases, and the second material has a positive TCR over the temperature range, the positive TCR causing a resistance of the second material to increase as a temperature of the second material increases; wherein a ratio of a thickness of the second material to a thickness of the first material can be approximated as a ratio of the negative resistance temperature coefficient (TCR) of the first material to the positive resistance temperature coefficient (TCR) of the second material.

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