RU2319246C1 - Thin-film resistor - Google Patents

Abstract

FIELD: microelectronics; thin-film microassemblies; developing and producing thin-film resistors on insulating substrates.

SUBSTANCE: proposed thin-film resistor has rectangular resistor unit, two opposing comb-shaped electrodes of multilayer conductive structure, and n rectangular resistor units with n ≥ 2 disposed in parallel with electrode width; in addition it has (n - 1) rectangular resistor units disposed between crests of one of electrodes and bases of other electrode so that resistive strip of uniform resistive material formed between electrodes acquires meander-like shape of equal width free from breaks.

EFFECT: simplified design, facilitated manufacture, reduced low value of resistance range at desired topologic and design dimensions.

1 cl, 6 dwg

Description

FIELD OF THE INVENTION

The invention relates to the field of microelectronics and can be used in the manufacture of thin-film microassemblies, and more specifically for the design and manufacture of thin-film resistors on dielectric substrates.

State of the art

Known thin-film resistor (TPR) of a rectangular shape [1]. The disadvantage of this type design TPD is that the shape factor k at _F ≤0,1 begins a significant increase of resistance R _EP of its electrodes and increasing the contribution of the unstable resistance to the total resistance of the resistor.

In a typical case, the contact pads for measuring the TPR resistance are connected to the electrodes so that the current flows sequentially through the first electrode, then through the second electrode. Denoting the length of the resistive element and its electrodes by l, and the width by b, we obtain

where ρ _p - specific surface resistance of the conductive film (electrodes): k _Ф = l / b. At small values of k _{f, the} resistance R of the _{electric field} increases the overall resistance of the TPR and worsens its temperature stability due to the high sensitivity of the resistance of the conductive film to temperature. Thus, the limitation of k _f ≥0.1 [2] is a serious obstacle in the design of thin-film microassemblies, because significantly reduces the range of TPR resistances manufactured on one board.

A known method of manufacturing TPR [3], which consists in spraying a resistive layer and a multilayer conductive structure onto a substrate, after which the first photolithography is carried out, after which through etching of all sprayed layers to the substrate is performed. In the second photolithography, the entire substrate is coated with photoresist except for rectangular windows above the resistive element, after which etching of the multilayer conductive structure is performed.

The disadvantage of this method is the high cost of manufacturing TPR associated with the need for re-etching the conductive layer.

Known thin-film resistor (prototype) and method (prototype) of its manufacture (see, RF patent No. 2231150, НСС 7/00, 17/00. Thin-film resistor and method of its manufacture / V.G. Spirin. - Publish. 06.20.2004 ) [4], allowing to expand the range of TPR resistances manufactured on one board.

According to a known technical solution, the TPR design (prototype) contains a rectangular resistive element and two electrodes of a multilayer conductive structure that have a comb shape and n resistive elements parallel to the width of the electrodes, and n-1 rectangular windows that are not occupied by film elements and located at the end of the resistive elements perpendicular to them, and form factor _F k each resistive element should be within 0,07≤k _F ≤0,13, wherein the electrode length should be not less than the length of the resistive elements.

The known method (prototype) for the manufacture of TPR consists in spraying a resistive layer and a multilayer conductive structure onto a substrate and performing double photolithography, and after the first photolithography, counter-comb electrodes are formed by etching the multilayer conductive structure, and resistive elements are formed by the second photolithography. In the second photolithography, a photoresist is applied to the entire resistor except for the windows, the width of the windows is equal to the minimum width of the gap between the electrodes, which is technologically achievable, after which the resistive layer is etched in the windows.

The disadvantages of the known technical solutions are the high complexity of the design of the TPR, as well as the complexity of its manufacture. Additional disadvantages include a rather high boundary of the lower resistance range for given topological and structural dimensions of the TPR.

SUMMARY OF THE INVENTION

The objective of the invention is to reduce the complexity of the design of the TPR, reduce the complexity of manufacturing AND IP, as well as reduce the border of the lower resistance range for given topological and structural dimensions of the TPR.

The problem is achieved due to the fact that the thin-film resistor contains a rectangular resistive element, two comb-shaped electrodes of a multilayer conductive structure with ridges located towards each other, and n rectangular resistive elements with n≥2 located parallel to the width of the electrodes, and additionally has (n-1) rectangular resistive elements located between the ends of the ridges of one of the electrodes and the bases of the other of the electrodes so that formed between by birth, the resistive strip is made in the form of a meander of the same width, without gaps, from a homogeneous resistive material.

The task is also achieved due to the fact that the method of manufacturing a thin-film resistor consists in spraying a resistive layer onto a dielectric substrate, onto the surface of which a multilayer conductive structure is applied, and then using photolithography, patterns of the resistor and contact pads are comb-shaped, and the photolithography process is carried out once, as a result of which patterns of electrodes are formed on a multilayer conductive structure.

Features

Distinctive features of the claimed design TPR in comparison with the prototype are:

1. Using as an additional element of conductivity (resistance) (n-1) sections of the resistive film located between the ends of the protrusions of one of the comb electrodes and the base of the other of the comb electrodes.

2. The location (n-1) of the resistive elements relative to the electrodes.

Distinctive features of the claimed method of manufacturing TPR in comparison with the prototype are:

1. Reducing the number of technological operations of photolithography to one.

2. No need for precise positioning of the coating with a photoresist to form (n-1) windows of a given width in different coordinate regions of the substrate.

List of drawings

The design of the TPR is shown in Fig. 1 by the frontal and profile projections.

The structural elements are indicated by the following positions: 1 - dielectric substrate; 2 - resistive layer; 3 - comb-shaped electrodes from a multilayer conductive structure with ridges located towards each other; A and B are the connection points of the resistor in the electrical circuit.

Figure 2 presents the electric model of the TPR section, in which: I - current flowing through the resistor; ρ _ij is the specific surface resistance of the sections of the resistor layers; φ _ij are the node potentials of the sections of the resistor layers.

удельном поверхностном сопротивлении резистивного слоя

Figure 3 presents the field of nodal potentials φ _ij [mV] obtained as a result of computer simulation at I = 1 mA, specific surface resistance of a multilayer conductive structure

surface resistivity of the resistive layer

Information confirming the possibility of implementation

The invention is illustrated in figures 1-3. The simplicity of the TPR design shown in FIG. 1 is obvious. The GPR made according to this design consists of only three dissimilar elements: a dielectric substrate 1, a rectangular resistive layer 2 and comb electrodes 3, preferably made of a multilayer conductive structure, for example, V-Cu-Ni or V-Al.

It is possible to calculate the resistance of such a resistor at the design stage using the analytical dependences known from [1–3] only with a large degree of approximation, since it is impossible to take into account all the edge effects and trajectories of the lines of force of the electric field (streamlines) passing through all the structural elements of figure 1. However, this situation can hardly be considered a big drawback of the claimed technical solution. For an approximate assessment of the TPR resistance, it is sufficient to use computer simulation using the circuit of Fig. 2 as an electrical model, and an accurate estimate can be obtained by measuring on a full-scale model (experimental laboratory samples). The circuit of Fig. 2 sufficiently imitates the electrical phenomena (fields) of film structures, and the nodal potentials φ _ij completely determine the magnitudes and directions of the surface currents i _ij flowing through all the elements of the TPR structure.

- второго, можно достаточно точно рассчитать сопротивление ТПР и электродов по формулеOn figa presents the result of electrical modeling of the prototype, figb claimed technical solutions. Selecting geometrically similar points with potentials φ _ij on the plane of the first comb electrode and with potentials

- second, you can accurately calculate the resistance of the TPR and electrodes according to the formula

where m is the number of similar nodal points on each electrode (in the ideal case, m → ∞), I is the current specified in the simulation. A fragment of a full listing of the field in Fig. 3c is the result at a current I = 1 mA, and the values of φ _{ij are} obtained in mV.

в качестве многослойной проводящей структуры 3 использовались материалы V-Al с удельным поверхностным сопротивлением

топологические и конструктивные размеры сохранены.The main modeling parameters carried out to analyze the claimed technical solution were chosen the same as those of the prototype: substrate 1 is made of ceramic material; resistive layer 2 is made of alloy PC3710 with a specific surface resistance of this layer

as a multilayer conductive structure 3 used materials V-Al with a specific surface resistance

topological and design dimensions are saved.

The analysis of the field of figure 3 shows that for the proposed method, the resistance of the resistor is R = 17.203 Ohms and the resistance of the electrode is 0.048 Ohms, and for the prototype R = 20.032 Ohms and the resistance of the electrode is 0.051 Ohms. Thus, the claimed technical solution allows to reduce the boundaries of the lower resistance range with the same topological and structural dimensions of the TPR.

The proposed method is implemented in the following sequence. A resistive layer 2 is applied to the dielectric substrate 1 (FIG. 1), and then a multilayer structure 3. Next, one photolithography is carried out — comb-shaped electrodes 3 are formed by etching an unprotected photoresist multilayer conductive structure.

The known method (prototype) [4] in comparison with the claimed requires an additional photolithography operation and therefore has a higher complexity, which is obvious from the above. The need for accurate positioning in the plane of the substrate of the photoresist coating for the formation of through windows complements the complexity of the prototype in comparison with the proposed technical solution.

Information sources

1. Matson E.A., Kryzhanovsky D.V. Reference guide on the design of microcircuits. - Minsk: Higher school, 1982, - P. 42-48, Fig. 3.1.

2. Efimov I.E., Kozyrev I.Ya., Gorbunov Yu.I. Microelectronics.- M.: Higher School, 1987, - P.169.

3. Bondarenko O.E., Fedotov L.M. Structural and technological basis for the design of microassemblies. - M.: Radio and Communications, 1988, - P. 49-51, Fig. 2.56.

4. RF patent №2231150, Н 01 С 7/00, 17/00. Thin film resistor and method for its manufacture. - Publ. 20. 06. 2004.

Claims (1)

A thin-film resistor containing a rectangular resistive element, two comb-shaped electrodes of a multilayer conductive structure with ridges located opposite each other, and n rectangular resistive elements with n≥2 parallel to the electrode width, characterized in that it additionally has (n-1) rectangular resistive elements located between the ends of the ridges of one of the electrodes and the bases of the other of the electrodes so that the resistive strip formed between the electrodes Helen in the form of a "meander" of the same width, without breaks, from a homogeneous resistive material.

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