KR100862162B1 - Embedded resistive thin film layer and deposition method thereof onto substrate to be deposited - Google Patents

Abstract

A buried type electrically resistive thin film in which about 1 to 30.11 atomic% of nanometer-sized noble metal particles are uniformly distributed on a tantalum nitride (Ta-N) base material based on 100 atomic% of tantalum nitride, and a deposition method thereof Is disclosed. Such buried electrical resistive thin film satisfies the relatively high electrical resistance value characteristics and the relatively low thermal resistance coefficient characteristics at the same time, and can be embedded in a wide range of circuits, as well as more precise control with lighter and thinner electronic devices. Make it possible.

Recessed electrically resistive thin film, buried resistor

Description

Embedded resistive thin film and deposition method thereof {EMBEDDED RESISTIVE THIN FILM LAYER AND DEPOSITION METHOD THEREOF ONTO SUBSTRATE TO BE DEPOSITED}

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 schematically illustrates one exemplary reactive co-sputtering apparatus for producing a buried electrical resistive thin film according to the present invention.

2 is a process flowchart illustrating a process of depositing a buried type electrically resistive thin film on a semiconductor substrate in order.

3 is a view showing the shape of a pattern manufactured using the process shown in FIG.

4 is a diagram of a pattern used to make the shape of the pattern shown in FIG.

5 is a view showing a change in the silver content and the specific resistance of the tantalum nitride according to the power density value of the silver target of the precious metal used in the present invention.

FIG. 6 is a graph showing XPS test results when nanometer-sized silver (Ag) particles are distributed in an amount of 23 atomic% based on 100 atomic% tantalum nitride in a tantalum nitride (Ta-N) base material.

FIG. 7A is a TEM image of a buried electrically resistive thin film made of Ta ₁ N ₂ , and FIG. 7B is a pattern in which nanometer-sized silver (Ag) particles are distributed in an amount of 23 atomic% in a Ta ₁ N ₂ base material TEM picture of a buried type electrically resistive thin film according to the invention.

8 is a graph showing the temperature resistance coefficient of the buried type electrically resistive thin film manufactured according to the present invention.

FIELD OF THE INVENTION The present invention relates to the field of buried electrically resistive thin films, and more particularly to relatively high electrical resistance values (eg, 2500 μΩ-cm to 8700 μΩ-cm) and relatively low thermal resistance coefficients ("TCR"). It relates to a buried type electrically resistive thin film having a resistivity (eg, -500 ppm / 占 폚 to +500 ppm / 占 폚) and a deposition method thereof.

The general trend of electronic products has been developed for the purpose of high functionalization through high integration and high clocking, and accordingly, a high specific resistance having a low high frequency attenuation rate is required in a high clock. In addition, it is required to improve the performance of the buried type electrically resistive thin film body capable of maintaining a stable resistance within the operating temperature range of the electronic products. This may be evaluated as a change in resistance characteristics according to temperature change, that is, a TCR value, and a general calculation thereof is as follows.

Where

는 초기온도에서의 저항을 나타내고;

Represents resistance at initial temperature;

는 최종온도에서의 저항을 나타내며;

Represents resistance at final temperature;

은 측정시초기 온도를 나타내고;

Represents the initial temperature at the time of measurement;

는 측정시 최종온도를 나타낸다.

Indicates the final temperature at the time of measurement.

Existing typical resistors are chip-type resistors, and the area occupied by chip-type passive elements of 1 mm or less is too large to cope with high integration. In addition, since the chip device is manufactured and assembled independently of the substrate or the IC, there are problems of circuit design inefficiency, reliability deterioration due to soldering, cumbersome assembly process, and cost increase.

Embedded resistors or otherwise embedded electrically resistive thin films ('embedded resistors' and 'embedded electrically resistive thin films' referred to throughout the specification are for convenience and are not specified otherwise). The advantage of the device is that the size of the device is significantly reduced, and built-in beyond the limit of mounting only on the surface, the overall size of the board can be significantly reduced, and the resistance of the pattern can be flexibly varied by the design of the pattern. Because it can be implemented, it is possible to implement a variety of properties than to assemble the relevant parts of the specified standard. In addition, the wiring of the circuit can be implemented with low inductance and short length, thereby improving switching speed and reducing EMI effect, and embedding not only on the substrate surface but also internally. Freedom of board design is increased. In addition, as the number of parts to be assembled is reduced, the cost of supply and management of parts can be reduced, and the soldering parts can be reduced, so that higher reliability can be secured, and the need to use lead is prevented. Can be.

However, the difficulty in developing such embedded resistors is that it is difficult to produce higher resistance values in the unit area due to the miniaturization of resistors, and it must be possible to manufacture them through a thin film process for high integration. That is, research on the application of thin film deposition and photolithography processes is required.

On the other hand, the advantage of Ta-N resistor is that it can make a wide sheet resistance range compared to Ni-Cr resistor (up to 134μΩ-cm) material widely used, so it is possible to make high integration and manufacture various resistors and to react with metal electrodes. There is no problem of mutual mixing because it does not happen. In addition, it is chemically stable and has excellent compatibility with dissimilar materials as compared to Ni-Cr, thereby improving reliability. Compared with current Ni-Cr and Ta-N resistances made of chip resistors, Ta-N has been shown to be superior in humidity resistance and co-deposition of metals in Ta-N substrates. When the nanocomposite is formed by co-deposition, an improved resistance characteristic can be expected. The thin film nanocomposite resistors have the following characteristics.

First, a resistor made of nanometer-sized metal particles dispersed in an insulating matrix has a thin film shape and high resistance and low coefficient of thermal resistance.

Second, it is currently used as a resist material in the form of cermet, and a representative example is a composite of SiO-Cr (only SiO-Cr is currently commercialized).

Third, the combination of various insulating matrixes and nanometer-sized metals has the possibility of simultaneously obtaining high resistance and low thermal resistance coefficient.

The electrical properties of the resistors should have a wide range of resistance and stable thermal resistance coefficient. The conventional known technologies for resistors using tantalum-based ceramics include thin film resistors using TaN _0.1 , Ta ₂ N, TaN, and TaON. have. However, although tantalum nitride resistors can realize a wide range of resistance values, they are limited in use because the thermal resistance coefficients are not stable. In particular, since a thin film resistor composed only of tantalum nitride has a very large negative thermal resistance coefficient, it is not significant to realize a high resistance value using only tantalum nitride. Therefore, the tantalum-based ceramic resistor has a very low specific resistance value in order to obtain a stable heat resistance coefficient value.

Such resistors may be formed into thin / thick films to form high-precision and high-resistance materials, such as pyrolysis, electroplating, electroless plating, and physical vapor deposition. However, the temperature range of the available base materials, ease of manufacture of resistors, The manufacturing method of the thin film type resistive element which is used most recently in recent years due to the economical cost of production is sputtering, one of the physical vapor deposition methods. As a material of a conventional resistive thin film coated with a thin film on the surface of a resistor base material by sputtering, nickel (Ni) -chromium (Cr), copper (Cu) -manganese (Mn), and nickel (Ni) -chromium (Cr) -Silicon (Si), Nickel (Ni)-Chromium (Cr)-Aluminum (Al), Tantalum Nitride (Ta-N), etc. are synthesized, but the material of this resistive thin film has a specific resistance value for high frequency attenuation and If a circuit of a precision electronic device is not designed because it does not satisfy the thermal resistance coefficient, an error tolerance range is extended, which causes a problem of deterioration of precision. In addition, Ta-N-based nanocomposites include Ta-N-Cu-based nanocomposites. However, due to the low equilibrium nitrogen partial pressure of Cu during the process, Cu does not exist as a metal but exists as a metastable CuN. Since the heat treatment must be performed at a high temperature of at least 400 ° C. or more, the selection of the substrate is restricted.

Therefore, in order to manufacture highly precise electronic devices such as high-precision electronic measuring equipment and microcomputers, there is an urgent need to develop materials having higher specific resistance values, lower thermal resistance coefficients, and higher degree of freedom of processing than conventional electrical resistive thin films. Accordingly, in the present invention, the fabrication of a Ta-N-Ag-based nanocomposite thin film resistor using sputtering and photolithography processes was attempted.

The present invention has been made to solve the above problems of the prior art, an object of the present invention by uniformly distributing the nanometer size precious metal inside the tantalum nitride thin film, the relatively high electrical resistance value characteristics and relative It is an object of the present invention to provide a buried type electrically resistive thin film which simultaneously satisfies low thermal resistance coefficient characteristics.

Another object of the present invention is to provide a method for depositing the above-described buried type electrically resistive thin film on the surface to be deposited of the substrate to be treated.

In order to achieve the above object, the present invention, in the tantalum nitride (Ta-N) base material based on 100 atomic% tantalum nitride, noble metal of nanometer size, for example, silver, gold and platinum particles 1 Provided is a buried type electrically resistive thin film having a uniform distribution of from 30.11 atomic%, preferably 4.55 atomic% to 30.11 atomic%, more preferably 17 atomic% to 24 atomic%.

In addition, the present invention provides a relatively high electrical resistance value characteristic (particularly, 2500 µΩ-cm to 8700 µΩ-cm) and a relatively low thermal resistance coefficient characteristic (particularly -500 ppm / ° C) on the surface to be deposited of the substrate to be treated. As a method of depositing a buried type electrically resistive thin film which simultaneously satisfies +500 ppm / ° C),

(a) depositing tantalum nitride (Ta-N) from a target tantalum source material (e.g., tantalum itself or an alloy or composite containing tantalum) on a surface to be deposited of the substrate to form a tantalum nitride film; ; And

(b) at the same time as or after step (a), a noble metal (e.g., silver, gold or platinum) from a noble metal source material on the surface to be deposited or tantalum nitride film of the substrate to be treated; Depositing itself or a combination thereof in a nanometerized particle size to uniformly distribute nanometer-sized noble metal particles within the tantalum nitride film, thereby embedding the buried material on the surface to be deposited of the substrate to be treated. A method of depositing an electrically resistive thin film is provided.

When the process of step (a) and step (b) is a coping process, the power density value of the noble metal target is 0.4W / cm ² to 1.1W / cm ² , preferably 0.7W / cm ² to 0.95 It is preferred that it is W / cm ² .

Step (a) and step (b) may also be accomplished by an ion beam or laser ablation process.

Abbreviations used herein have the following meanings unless otherwise indicated: ° C = degrees Celsius; ppm = parts per million; PCB = printed circuit board, CVD = chemical vapor deposition, TCR = temperature coefficient of resistivity, RBS = Rutherford backscattering spectroscopy, XPS = X-ray photoelectron spectroscopy, TEM = Transmission electron spectroscope.

The buried type electrically resistive thin film according to the preferred embodiment of the present invention is mainly formed of tantalum nitride having a composition of tantalum and nitrogen in a ratio of 2: 1 to 1: 2. In order to manufacture a buried type electrically resistive thin film body having a high specific resistance value, a composition of Ta: N = 1: 2 is preferable. In order to control the coefficient of thermal resistance, various levels, typically from 1 to 30.11 atomic percent of the total material, consist of precious metal particles and are prepared using co-sputtering. Among them, the electrically resistive thin film having a coefficient of thermal resistance of less than 100 ppm is a thin film containing 17 atomic% to 24 atomic% Ag in the Ta ₁ N ₂ base material, and its resistance is high resistance value of 8700μΩ-cm at 2500μΩ-cm. Had

Hereinafter, the metal that forms the Ta-N base material and the nanocomposite using a co-sputtering method is limited to silver (Ag) in consideration of economic feasibility, but gold (Au) and It is to be understood that noble metals including platinum (Pt) are also included within the scope of the present invention. In addition, hereinafter, the method of depositing a buried type electrically resistive thin film according to the present invention is limited to the coping method. However, those skilled in the art having knowledge of the present specification, in addition to the coping method, process by ion beam and laser ablation (laser) Ablation) may also be considered.

1) Sample Preparation

In the present invention, experiments were performed using Corning 1737 glass and FR-4 to obtain a more accurate and reproducible resistivity value, and Si (100) wafer for basic analysis such as phase analysis and structural analysis. Was used. In order to clean the substrate before film formation, trichloroethylene, acetone, and isopropyl alcohol (IPA: isopropyl alcohol) were each ultrasonically cleaned for 10 minutes. Thereafter, plasma treatment was performed for 10 minutes at 300 W input power and 5 mTorr process pressure to improve adhesion of the thin film.

2) Synthesis of Thin Film

Synthesis methods of Ta-N thin film resistors include sputtering using a Ta-N target and reactive sputtering with a Ta target. In the former case, the control of the process variable is simple, but only a fixed resistivity can be obtained. In the latter, the control of the process variable is relatively difficult, but a very wide specific resistivity can be obtained according to the N ₂ partial pressure.

In the present invention, the experiment on the resistance change of Ta-N thin film according to the process pressure was performed using a DC magnetron sputter. At this time, the base pressure was 3X10 ^-7 Torr or less, the process pressure was 5 mTorr, and the power density of the Ta target was fixed at 8.8 W / cm ² , and the power density of the Ag target was 0 to 1.1 W /. The experiment was carried out while changing to cm ² . 1 is a schematic of the device used in this experiment. The gun is tilted 30 ° relative to the chamber wall to allow the deposition of different types of materials at the same time with DC and RF magnetron co-sputtering systems. In addition, the lower substrate holder can rotate a high speed of 0 ~ 30rpm to synthesize a higher quality thin film.

3) Photolithography Process

In order to determine the thermal resistance coefficient and patterning characteristics of the thin film manufactured by the above method, the experiment was carried out using the lift-off method. PR used in the experiment used a negative series 6000PY. In order to increase the adhesion between the substrate and the PR before PR coating, spin coating was performed after surface treatment with hexamethyldisilazane (HMDS). Spin coating was carried out in three processes: dispersion (1000 rpm, 10 seconds), coating (3000 rpm, 25 seconds), and drying (500 rpm, 5 seconds). Thereafter, pre-bake was performed at 150 ° C. for 1 minute using a hot plate to dry the solvent of PR, and then irradiated with 1,100 mJ / cm ² using an aligner. The pattern was transferred. Thereafter, post-bake was performed at 100 ° C. for 1 minute, and development was performed for 45 seconds using an RD6 developer. After the deposition of a thin film type resistor using a sputter as a pattern manufactured by the above process, the PR strip was completed. Ag electrode was formed through the above procedure once more to measure the thermal resistance coefficient to form a completed pattern (pattern). FIG. 2 is a schematic diagram of a PR process, and FIG. 3 is a shape of a pattern manufactured using the process of FIG.

4) Resistance characteristic measurement

A four-point probe was used to measure the resistance of the deposited thin film. In addition, a patterned resistor could be implemented using a pattern as shown in FIG. 4 using a lift-off process for measuring the thermal resistance coefficient. Measurement range of the thermal resistance coefficient was 0 ~ 100 ℃, it was measured using a constant temperature and humidity bath controlled to within ± 0.5 ℃ for precise measurement.

The general experiment is to synthesize a nanocomposite resistor having a ratio of 4.55 atomic% to 30.11 atomic% as the Ta: N atomic ratio is changed from 2: 1 to 1: 2 ratio of Ag target power density. Among them, the resistor having a thermal resistance coefficient of less than 100 ppm is a resistor containing 17 atomic percent to 24 atomic percent Ag in the Ta ₁ N ₂ base material, and its specific resistance is high resistivity of 8700 μΩ-cm at 2500 μΩ-cm. Had a value. 5 is a result of measuring the RBS measurement results and the change in the specific resistance thereof of the test specimens tested while varying the power density value of the Ag target in the amorphous Ta-N base material having Ta ₁ N ₂ . As a result of the RBS experiment, the higher the power density of the Ag target, that is, the higher the Ag content, the specific resistance ranged from 8700 μΩ-cm to 2500 μΩ-cm. This is because the higher the content of Ag in the Ta-N base material, the higher the number of electrons. In the experiment, the content of Ag was tested up to 30.11 atomic%, but the practical value was up to 24 atomic%, and the resistivity at this time was The value is 2500μΩ-cm, which means the lowest resistivity available as a buried resistor.

6 shows XPS test results of a resistor having 23 atomic% Ag. As a result, tantalum (Ta) was found to combine with nitrogen to form Ta-N, and Ag was present as Ag metal itself without reacting with tantalum (Ta) or nitrogen (N). This means that, unlike the Ta-N-Cu composition, a separate heat treatment is not necessary. Thus, the Ag resistance is mixed with the Ta-N matrix and does not react with nitrogen. You can indirectly know that you are controlling.

7A is a TEM photograph of a resistor made of Ta ₁ N ₂ , and FIG. 7B is a TEM photograph of a resistor having Ag added to the Ta ₁ N ₂ base material by 23 atomic%. It can be seen from FIG. 7 (a) that Ta ₁ N ₂ in an amorphous state exists, and FIG. 7 (b) shows that Ag is impregnated and dispersed evenly in the Ta ₁ N ₂ base material. This reaffirms the XPS result of FIG. 6, which means that the Ag metal is uniformly dispersed in the metal state without reacting with Ta or N in the Ta ₁ N ₂ base material. The nanocomposite plays a role of stabilizing the thermal resistance coefficient without significantly reducing the specific resistance compared to the compound-type material.

8 is a result of measuring the thermal resistance coefficient value of Ta ₁ N ₂ and Ta ₁ N ₂ -Ag nanocomposite (nanocomposite). The concentration of Ag was from 17 atomic% to 24 atomic% in the range which can be used as a buried resistor. At this time, the value of the thermal resistance coefficient was -478 to + 370ppm / ℃, and in the other composition range, it was not more than 500ppm / ℃ as a resistor (the range of the thermal resistance coefficient that can be used as the resistor is -500ppm / ℃ to +500 ppm / ℃). This is an example showing that by co-deposition of Ag on the Ta-N base material to synthesize the Ta-N-Ag nanocomposite (nanocomposite) can be thermally stable and have a high resistivity value.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention described in the claims below. It will be appreciated.

As described above, the present invention is characterized in that co-sputtering of tantalum and silver in a nitride atmosphere enables the synthesis of a resistor having a high specific resistance and a low thermal resistance coefficient, and the power density of the Ag target sequentially. By controlling the TCR value of 32ppm / ^o C at a resistivity value of about 5900μΩ-cm can be embedded in a wide range of circuits, it is possible to reduce the thin and light electronic devices and more precise control.

Claims (17)

delete delete delete delete delete delete A method of depositing a buried type electrically resistive thin film having an electrical resistance value in the range of 2500 μΩ-cm to 8700 μΩ-cm and a thermal resistance coefficient in the range of -500 ppm / ° C. to +500 ppm / ° C. on the surface of the substrate to be treated. As (a) depositing tantalum nitride (Ta-N) from the tantalum source material to be deposited on the deposition target surface of the substrate to be formed to form a tantalum nitride film; And (b) At the same time as or after the step (a), the inside of the tantalum nitride film is deposited by depositing noble metal particles from a noble metal source material on the surface to be deposited or the tantalum nitride film of the substrate to be treated. A method of depositing a buried electrical resistive thin film on a surface to be deposited of a substrate to be treated, comprising the step of uniformly distributing noble metal particles. delete 8. The method according to claim 7, wherein the steps (a) and (b) are cosuttering processes under a nitrogen atmosphere. The method according to sputtering process wherein a target power density of the noble metal from the noble metal material origins of 0.4W / cm ² to 1.1W / cm ² in the step (b) according to claim 9. 10. The method of claim 9, wherein a range of power density of the noble metal target characterized in that a 0.7W / cm ² to about 0.95W / cm ^2. 8. A method according to claim 7, wherein the steps (a) and (b) are performed by ion beams. 8. The method of claim 7, wherein the process of step (a) and step (b) is a process by laser ablation. 8. The method of claim 7, wherein the precious metal is selected from the group consisting of silver (Ag), gold (Au) and platinum (Pt). 10. The method of claim 9, wherein the precious metal is selected from the group consisting of silver (Ag), gold (Au) and platinum (Pt). The method of claim 12, wherein the precious metal is selected from the group consisting of silver (Ag), gold (Au), and platinum (Pt). The method of claim 13, wherein the precious metal is selected from the group consisting of silver (Ag), gold (Au) and platinum (Pt).

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