Preparation method of resistive film

Abstract

The invention discloses a preparation method of a resistive film. A two-pole direct-current pulse power supply is arranged in magnetron sputtering equipment, and the two-pole direct-current pulse power supply is provided with two bipolar direct-current pulse output ends with opposite output polarities and adjustable duty ratios. The two output ends are connected with two target materials which are made of metal and ceramic materials and are different in resistivity respectively, when the resistive thin film with high sheet resistance is prepared, the duty ratio of negative polarity direct current pulses of the output ends connected with the target materials with high resistivity is relatively high, and when the resistive thin film with low sheet resistance is prepared, the duty ratio of negative polarity direct current pulses of the output ends connected with the target materials with high resistivity is relatively low. The duty ratio of the negative polarity direct current pulse of the output end connected with the target material with the low resistivity is relatively high. By accurately controlling the duty ratio of the direct-current pulse, the effect that the square resistance of the resistive film changes by multiple times can be achieved on the premise that the thickness of the resistive film is not changed.

Description

Technical Field:

[0001] The present invention relates to the technical field of magnetron sputtering film formation, and specifically to a preparation method of a resistive film that can form a multi-resistivity sputtering target at one time and then obtain a thin film resistor product within a thickness range. Background Art:

[0002] In the field of thin film technology, magnetron sputtering equipment is a commonly used device. It can achieve the sputtering of the target material by controlling the electric field and magnetic field, thereby preparing the required thin film. In the field of thermal printer head manufacturing technology, resistive films are used to manufacture resistive heating elements. The sheet resistance and film thickness of resistive films are crucial parameters. The product of the sheet resistance and film thickness is called the resistivity of the thin film. The resistivity of the thin film depends to a large extent on the resistivity of the target. This means that when using targets with the same resistivity to prepare two resistive films with a sheet resistance difference of n times, the thickness of the resistive films will also have the same multiple difference. However, the thickness of the resistive film will have a great impact on the performance of the device formed by the resistive film. For example, when the thickness of the resistive film is below 20 nm, the power tolerance of the resistive film may decrease. When the thickness of the resistive film is greater than 100 nm, the step difference formed after patterning the resistive film may cause cracks in the protective layer covering the resistive film, thereby reducing the reliability of the device formed by the above resistive film. Moreover, increasing the thickness of the resistive protective film will also cause problems such as increased manufacturing costs, longer process time, and reduced production efficiency. The thickness of the resistive film is within a reasonable range.

[0003] To meet the above thickness requirements, in the existing technology, sputtering targets made of high melting point metals and ceramic materials with target resistivity are used. Usually, targets with different resistivities are used to prepare resistive films with different sheet resistances. Several sputtering devices equipped with targets with different resistivities can be set up to meet the preparation requirements of different sheet resistances. It is also possible to replace targets with different resistivities in the same device to meet the preparation requirements of different sheet resistance films. However, the above solution of setting up several sputtering devices equipped with targets with different resistivities to meet the preparation requirements of different sheet resistances requires purchasing multiple devices, resulting in high equipment costs. Replacing targets with different resistivities on the same device to meet the preparation requirements of different sheet resistance films has the problem of reduced equipment utilization efficiency. In addition, with product upgrade and improvement, the change in the sheet resistance of the resistor is further increased on the premise of meeting the manufacturing thickness,

[0004] that is, there is an urgent need for a preparation method of a resistive film with a thickness of within a range and a wide range of sheet resistance changes. Summary of the Invention:

[0005] In view of the drawbacks and deficiencies in the prior art, the present invention provides a method for preparing a resistive film. The method involves forming a resistive film by sputtering a multi-resistivity sputtering target in one step, resulting in a finished product without obvious delamination, and thus meeting the wide sheet resistance adaptability within a set thickness range.

[0006] The present invention is achieved through the following measures:

[0007] A method for preparing a resistive film, characterized in that two DC pulse signal output circuits with opposite polarities are formed through a bipolar DC pulse power supply. The two DC pulse signal output circuits are respectively connected to a duty cycle adjustment circuit. The output terminals of the two DC pulse signals are respectively connected to two targets with different resistivities. By adjusting the output duty cycles of the two DC pulse signals, the sputtering working states of the two targets with different resistivities are adjusted, and the film formation of two materials with different resistivities is completed. The thickness range of the obtained resistive film is 30 - 90 nm, and the sheet resistance range is 97 Ω - 1510 Ω.

[0008] To achieve the above object, the present invention is provided with a bipolar DC pulse power supply in a magnetron sputtering device. The bipolar DC pulse power supply has two output terminals with opposite polarities and adjustable duty cycles for DC pulses. Each DC pulse output terminal is correspondingly provided with a sputtering target. Both sputtering targets contain metal and ceramic materials, and the metal content ratios in the two sputtering targets are different. The target with a high metal content has a low resistivity, and the target with a low metal content has a high resistivity. Connect the two targets to the two output terminals of the bipolar DC pulse power supply. When the targets are energized and glow, the target into which the negative-polarity pulse is input ejects target atoms, and the target is the cathode. The target into which the positive-polarity pulse is input is the anode, that is, the polarity of the target changes with the periodic change of the pulse, and the number of atoms sputtered from the target varies with the width of the negative-polarity pulse.

[0009] In the present invention, when preparing a resistive film with a high sheet resistance, the duty cycle of the negative-polarity DC pulse at the output terminal connected to the target with a high resistivity is greater than the duty cycle of the DC pulse connected to the target with a low resistivity. When preparing a resistive film with a low sheet resistance, the duty cycle of the negative-polarity DC pulse at the output terminal connected to the target with a low resistivity is higher than the duty cycle of the DC pulse connected to the target with a high resistivity. By controlling the duty cycle of the DC pulse, within a small thickness change range of the resistive film, a large sheet resistance change range of the resistive film is achieved, thereby meeting the requirements of relatively stable thickness and large sheet resistance change for the resistive film.

[0010] In the present invention, the adjustable range of the duty cycle of the DC pulse output by the bipolar DC pulse power supply is

[0011] The present invention specifically includes the following steps:

[0012] Step 1: Prepare a magnetron sputtering device equipped with a bipolar DC pulse power supply. The magnetron sputtering device is provided with at least a preliminary vacuum chamber and a sputtering vacuum chamber. The adjustable range of the duty cycle of the DC pulse output by the bipolar DC pulse power supply is

[0013] Step 2: Install two sputtering targets composed of metal and ceramic materials with different metal content ratios and resistivities. The target with a relatively high metal content is a composite material of tantalum metal and silicon dioxide, with the mass ratio of tantalum metal being 85% and the resistivity being 10 Ω·μm. The target with a relatively low metal content is a composite material of tantalum metal and silicon dioxide, with the mass ratio of tantalum metal being 75% and the resistivity being 100 Ω·μm;

[0014] Step 3: Connect the two targets to the two output terminals of the bipolar DC pulse power supply respectively; Step 4: Install a ceramic substrate with an average surface roughness less than 10 nm on a fixture. The fixture moves horizontally in the preliminary vacuum chamber and the sputtering vacuum chamber of the magnetron sputtering device. Set the power density of the target to 5 w / cm 2 , set the conveying speed of the fixture to 2 mm / s - 3 mm / s, set the duty cycle of the negative polarity pulse of the output terminal connected to the target with a resistivity of 10 Ω·μm to 15 - 85%, set the duty cycle of the negative polarity pulse of the output terminal connected to the target with a resistivity of 100 Ω·μm to 85% - 15%, and obtain two resistive films with equal thickness and different sheet resistances on the surface of the ceramic substrate. The sheet resistances of the two resistive films are 97 Ω - 1510 Ω, and the thickness of the resistive film is 30 - 90 nm.

[0015] Compared with the existing technologies, the beneficial effects of the present invention are as follows: (1) When preparing the resistive film, by installing two sputtering targets composed of metal and ceramic materials with different metal content ratios, and using the connection method between the output terminals of the bipolar DC pulse power supply and the targets, the sheet resistance of the resistive film is effectively controlled. This method not only simplifies the preparation process, but also makes the thickness variation range of the resistive film relatively small, thereby improving the accuracy and stability of the resistance value of the resistive film; (2) When preparing the resistive film in the present invention, by adjusting the duty cycle of the DC pulse of the output terminal connected to the target with relatively low metal content, a resistive film with a relatively high sheet resistance can be prepared; by adjusting the duty cycle of the DC pulse of the output terminal connected to the target with relatively high metal content, a resistive film with a relatively low sheet resistance can be prepared. This preparation method of adjusting the resistance value according to requirements greatly expands the application range of the resistive film and improves the measurement accuracy and reliability of the resistive film; (3) Compared with using two targets with the same metal content, the preparation method of the present invention has a larger sheet resistance variation range of the resistive film under the condition of a relatively small thickness variation range of the resistive film. This not only improves the controllability of the resistance value of the resistive film, but also makes it possible to accurately measure the resistive film, meeting the high-precision requirements for the resistive film in the field of precision measurement technology. BRIEF DESCRIPTION OF THE DRAWINGS:

[0016] The Figure 1 working schematic diagram of the sputtering device in the present invention.

[0017] The Figure 2 schematic diagram of two-way bipolar DC pulse signals output by the sputtering device in the present invention. The Figure 3 schematic diagram of the working states of the bipolar DC pulse signals corresponding to the two-way targets in the present invention.

[0018] Reference numerals: 11 is a bipolar DC pulse power supply, 12 is the first output terminal, 13 is the second output terminal, 14 is a low-resistivity target A, 15 is a high-resistance target B, 16 is a ceramic substrate, output P1 is the output DC pulse waveform of the first output terminal of the bipolar DC pulse power supply 11, output P2 is the output DC pulse waveform of the second output terminal of the bipolar DC pulse power supply 11, Tp is the period of the DC output DC pulse, Td is the duration of the negative-polarity pulse, and the ratio of Td to Tp is the duty cycle. DETAILED DESCRIPTION OF THE EMBODIMENTS:

[0019] The present invention will be further described below with reference to the drawings and embodiments.

[0020] Embodiment 1:

[0021] This example presents a method for preparing a resistive film by setting twin targets with different resistivities and adjusting the duty cycle of the output terminals of a bipolar DC pulse power supply connected to the twin targets. The specific steps are as follows:

[0022] Step 1: Prepare a magnetron sputtering device equipped with a bipolar DC pulse power supply. The magnetron sputtering device is at least provided with a preliminary vacuum chamber and a sputtering vacuum chamber. The preliminary vacuum chamber and the sputtering vacuum chamber are respectively provided with a vacuum pumping and a vacuum measurement system. At an appropriate vacuum degree, for example, 10E-2 Pa, the isolation valve between the preliminary vacuum chamber and the sputtering vacuum chamber is opened. A fixture equipped with a ceramic substrate enters the sputtering vacuum chamber through the preliminary vacuum chamber. The background vacuum before film formation in the sputtering vacuum chamber is set to 10E-4 Pa. A heating means is provided in the preliminary vacuum chamber to heat the ceramic substrate to an appropriate temperature, for example, 200 °C, aiming to remove the water vapor adsorbed on the surface of the ceramic substrate. The duty cycle of the DC pulse output by the bipolar DC pulse power supply can be precisely adjusted, and the adjustable range is

[0023] Step 2: Install two sputtering targets composed of metal and ceramic materials with different metal content ratios and resistivities. For the target with a relatively high metal content, a composite material of tantalum metal and silicon dioxide is selected, with the mass ratio of tantalum metal being 85% and the resistivity being 10 Ω·μm. For the target with a relatively low metal content, a composite material of tantalum metal and silicon dioxide is selected, with the mass ratio of tantalum metal being 75% and the resistivity being 100 Ω·μm;

[0024] Step 3: Connect the two targets to the two output terminals of the bipolar DC pulse power supply;

[0025] Step 4: Install a ceramic substrate with an average surface roughness of less than 10 nm on the fixture. The fixture can move horizontally in the preliminary vacuum chamber and the sputtering vacuum chamber of the magnetron sputtering device. The gap between the target and the fixture is 80 mm. The gas introduced into the sputtering vacuum chamber is argon, with a flow rate of 60 sccm. The pressure of the vacuum chamber is 0.7 Pa. Set the power density of the target to 5 w / cm 2 , set the transfer speed of the fixture to 2 mm / s, set the duty cycle of the negative polarity pulse of the output terminal connected to the target with a resistivity of 10 Ω·μm to 55%, and set the duty cycle of the negative polarity pulse of the output terminal connected to the target with a resistivity of 100 Ω·μm to 45%. The sheet resistance of the resistive film prepared on the surface of the ceramic substrate is 398 Ω, and the thickness of the resistive film is 42 nm.

[0026] Example 2:

[0027] In this embodiment, the implementation manners of Step 1, Step 2, and Step 3 are the same as those of Step 1, Step 2, and Step 3 in Embodiment 1, and will not be elaborated here; Step 4: Set the power density of the target to 5 w / cm2, the conveying speed of the fixture to 2 mm / s, set the duty cycle of the negative-polarity pulse at the output terminal connected to the target with a resistivity of 10 Ω·μm to 24%, set the duty cycle of the negative-polarity pulse at the output terminal connected to the target with a resistivity of 100 Ω·μm to 76%. The sheet resistance of the resistive film prepared on the ceramic substrate surface is 760 Ω, and the thickness of the resistive film is 42 nm.

[0028] For the resistive films prepared according to Embodiment 1 and Embodiment 2, while keeping the target specifications, target power density, and fixture conveying speed the same, by adjusting the duty cycle of the negative-polarity pulse of the bipolar DC pulse power supply, the sheet resistance of the film in Embodiment 2 is about 1.9 times that of the film in Embodiment 1, and the film thicknesses of Embodiment 2 and Embodiment 1 are the same.

[0029] Embodiment 3:

[0030] In this embodiment, the implementation manners of Step 1, Step 2, and Step 3 are the same as those of Step 1, Step 2, and Step 3 in Embodiment 1, and will not be elaborated here; Step 4: Set the power density of the target to 5 w / cm2, the conveying speed of the fixture to 2.8 mm / s, set the duty cycle of the negative-polarity pulse at the output terminal connected to the target with a resistivity of 10 Ω·μm to 85%, set the duty cycle of the negative-polarity pulse at the output terminal connected to the target with a resistivity of 100 Ω·μm to 15%. The sheet resistance of the resistive film prepared on the ceramic substrate surface is 383 Ω, and the thickness of the resistive film is 30 nm.

[0031] Embodiment 4:

[0032] In this embodiment, the implementation manners of Step 1, Step 2, and Step 3 are the same as those of Step 1, Step 2, and Step 3 in Embodiment 1, and will not be elaborated here; Step 4: Set the power density of the target to 5 w / cm2, the conveying speed of the fixture to 2.8 mm / s, set the duty cycle of the negative-polarity pulse at the output terminal connected to the target with a resistivity of 10 Ω·μm to 15%, set the duty cycle of the negative-polarity pulse at the output terminal connected to the target with a resistivity of 100 Ω·μm to 85%. The sheet resistance of the resistive film prepared on the ceramic substrate surface is 1510 Ω, and the thickness of the resistive film is 30 nm.

[0033] For the resistive films prepared according to Embodiment 3 and Embodiment 4, while keeping the target specifications, target power density, and fixture conveying speed the same, by adjusting the duty cycle of the negative-polarity pulse of the bipolar DC pulse power supply, when the film thicknesses of Embodiment 4 and Embodiment 3 are the same, the sheet resistance of the film in Embodiment 4 is about 3.94 times that of the film in Embodiment 3.

[0034] Example 5:

[0035] In this example, the implementation manners of Step 1, Step 2, and Step 3 are the same as those of Step 1, Step 2, and Step 3 in Example 1, and will not be elaborated here; Step 4: Set the power density of the target to 5 w / cm2, the conveying speed of the fixture to 1.4 mm / s, the duty cycle of the negative polarity pulse at the output terminal connected to the target with a resistivity of 10 Ω·μm to 85%, and the duty cycle of the negative polarity pulse at the output terminal connected to the target with a resistivity of 100 Ω·μm to 15%. The sheet resistance of the resistance thin film prepared on the ceramic substrate surface is 97 Ω, and the thickness of the resistance thin film is 90 nm.

[0036] Due to the advancement of this technical solution, the thickness of the resistance thin film can be made not to change with the change of the sheet resistance of the resistance thin film. That is to say, the thickness of the resistance thin film is maintained within a reasonable range, and the sheet resistance of the resistance thin film can have a larger change range. In this way, it is not necessary to prepare multiple devices with different resistivity targets or frequently replace the target on the same device to meet the large change demand of the sheet resistance within the reasonable thickness range of the resistance thin film, which can reduce the equipment investment cost, improve the equipment utilization rate, and has broad application prospects.

Claims

1. A method for preparing a resistive thin film, characterized in that, A two-way DC pulse signal output circuit with opposite polarities is formed by a bipolar DC pulse power supply. The two-way DC pulse signal output circuits are respectively connected to a duty cycle adjustment circuit. The output terminals of the two-way DC pulse signals are respectively connected to two types of target materials with different resistivities. By adjusting the output duty cycle of the two-way DC pulse signals, the sputtering working states of the two target materials with different resistivities are adjusted, and sputtering film formation with two different resistivities is completed. The obtained resistance film has a thickness range of 30 - 90 nm and a sheet resistance range of 97 Ω - 1510 Ω.

2. The preparation method of a resistive thin film according to claim 1, wherein, A bipolar DC pulse power supply is provided in the magnetron sputtering equipment. The bipolar DC pulse power supply has two output terminals with opposite polarities and adjustable duty cycles for DC pulses respectively. One sputtering target is correspondingly arranged at each DC pulse output terminal. Both of the two sputtering targets contain metal and ceramic materials, and the metal content ratios in the two sputtering targets are different. The target with a high metal content has a low resistivity, and the target with a low metal content has a high resistivity. Connect the two targets to the two output terminals of the bipolar DC pulse power supply. When the targets are energized and glow, the target atoms are sputtered from the target into which the negative-polarity pulse is introduced. The target is the cathode, and the target into which the positive-polarity pulse is introduced is the anode, that is, the polarity of the target changes with the periodic change of the pulse, and the number of atoms sputtered from the target varies with the width of the negative-polarity pulse.

3. The preparation method of a resistive thin film according to claim 2, characterized in that, When preparing a resistance film with a high sheet resistance, the duty cycle of the negative-polarity DC pulse at the output terminal connected to the target material with a high resistivity is greater than the duty cycle of the DC pulse connected to the target material with a low resistivity. When preparing a resistance film with a low sheet resistance, the duty cycle of the negative-polarity DC pulse at the output terminal connected to the target material with a low resistivity is higher than the duty cycle of the DC pulse connected to the target material with a high resistivity.

4. The preparation method of a resistive thin film according to claim 3, characterized in that, The adjustable range of the duty cycle of the DC pulse output by the bipolar DC pulse power supply is 5. The preparation method of a resistive thin film according to claim 3, characterized in that, It includes the following steps: Step 1: Prepare a magnetron sputtering equipment provided with a bipolar DC pulse power supply. The magnetron sputtering equipment is at least provided with a preliminary vacuum chamber and a sputtering vacuum chamber. The duty cycle of the DC pulse output by the bipolar DC pulse power supply is adjustable; Step 2: Install two sputtering targets composed of metal and ceramic materials with different metal content ratios. Among them, the target with a relatively high metal content is a composite material of tantalum metal and silicon dioxide, with the mass ratio of tantalum metal being 85%, and the resistivity being 10 Ω·μm. The target with a relatively low metal content is a composite material of tantalum metal and silicon dioxide, with the mass ratio of tantalum metal being 75%, and the resistivity being 100 Ω·μm; Step 3: Connect the two targets to the two output terminals of the bipolar DC pulse power supply respectively; Step 4: Install the ceramic substrate with an average surface roughness less than 10 nm on the fixture. The fixture moves horizontally in the preparatory vacuum chamber and the sputtering vacuum chamber of the magnetron sputtering equipment. Set the power density of the target to 5 w / cm 2 , set the transfer speed of the fixture to 2 mm / s - 3 mm / s, set the duty cycle of the negative polarity pulse at the output terminal connected to the target with a resistivity of 10 Ω·μm to 15 - 85%, and set the duty cycle of the negative polarity pulse at the output terminal connected to the target with a resistivity of 100 Ω·μm to 85% - 15%. Two resistive films with the same thickness and different sheet resistances are prepared on the surface of the ceramic substrate. The sheet resistance range of the two resistive films is 97 Ω - 1510 Ω, and the thickness of the resistive film is 30 - 90 nm.

6. The preparation method of a resistive thin film according to claim 5, characterized in that, Two resistance films with a thickness of 30 nm and sheet resistances of 383 Ω and 1510 Ω respectively are prepared on the surface of the ceramic substrate.

7. The preparation method of a resistive thin film according to claim 5, characterized in that, Two resistance films with a thickness of 42 nm and sheet resistances of 760 Ω and 398 Ω respectively are prepared on the surface of the ceramic substrate.

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