Chromium silicide film and manufacturing method thereof

Abstract

To provide at least one of a film-coated substrate having a chromium silicide film which has a smaller change in resistivity due to temperature change and is also excellent in light transmittance, as compared with conventional chromium silicide resistive films, and a method for manufacturing the same.SOLUTION: A film-coated substrate includes a chromium silicide film containing chromium, silicon, nitrogen and oxygen and having a thickness of 300 nm or less, and a substrate.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a chromium silicide film and a method for manufacturing the same.

Background Art

[0002] Silicide materials such as chromium silicide (CrSi2) are used as silicide films in applications such as semiconductors and solar cells due to their characteristics. Since the characteristics of silicide materials can be controlled to either semiconductor characteristics or metal characteristics by controlling the state of the crystal phase, they are used as resistance films for various sensors.

[0003] Sensors equipped with a resistance film of silicide are applied in environments accompanied by temperature changes of about room temperature to 150°C, such as in automobiles. In order to improve the detection accuracy in an environment accompanied by temperature changes, a silicide film having resistance characteristics independent of temperature changes is required.

[0004] Furthermore, the silicide film is also expected to be applied to sensors that require optical characteristics in addition to resistance characteristics, such as image sensors, and a silicide film is being studied as a resistance film having excellent optical characteristics in addition to resistance characteristics.

[0005] For example, Patent Document 1 discloses that a chromium silicide film containing carbon and oxygen and a resistance element provided therewith have excellent resistance characteristics.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, since the resistive element having a chromsilicide film containing carbon and oxygen disclosed in Patent Document 1 is composed of a film-attached substrate formed on a silicon substrate or a ceramic substrate, it inherently has no light transmissivity and does not have optical properties applicable to an image sensor or the like.

[0008] An object of the present disclosure is to provide at least one of a film-attached substrate having a chromsilicide film with a small change in resistivity due to temperature change and excellent light transmissivity compared to a conventional chromsilicide resistive film, and a method for manufacturing the same. [Means for Solving the Problems]

[0009] The inventors of the present invention mainly focused on the influence of components other than chromium and silicon in a resistive film composed of a silicide film mainly composed of chromium and silicide, and conducted studies. As a result, it was found that by including specific components and controlling the film formation conditions, the physical properties of the silicide film are controlled, resulting in a film-attached substrate having a silicide film with resistive characteristics suitable as a resistive film and good optical properties.

[0010] That is, the present invention is as described in the claims, and the gist of the present disclosure is as follows. [1] A film-attached substrate comprising a chromsilicide film containing chromium, silicon, nitrogen, and oxygen, and having a film thickness of 300 nm or less, and a substrate. [2] The film-attached substrate according to [1] above, wherein the total content of chromium, silicon, nitrogen, and oxygen in the chromsilicide film is 100 atm%, and the content of chromium is 10 atom% or more and 30 atom% or less, the content of silicon is 30 atom% or more and 60 atom% or less, the content of nitrogen is 1 atom% or more and 40 atom% or less, and the content of oxygen is 1 atom% or more and 10 atom% or less. [3] The film-attached substrate according to [1] or [2] above, wherein the substrate is a substrate having an average total light transmittance of 80% or more. [4] The film - attached substrate according to any one of [1] to [3] above, wherein the average |TCR| of the chromium silicide film in the temperature range from 40°C to 150°C is 0 ppm / °C or more and 30 ppm / °C or less. [5] The film - attached substrate according to any one of [1] to [4] above, wherein the resistivity of the chromium silicide film at 30°C is 3000 μΩ·cm or more. [6] A method for manufacturing a film - attached substrate according to any one of [1] to [5] above, comprising a film - forming step of sputtering a chromium silicide film on a substrate in an atmosphere containing nitrogen and oxygen using a sputtering target containing chromium and silicon, and a heat - treatment step of heat - treating the film - attached substrate having the chromium silicide film. [7] The method for manufacturing a film - attached substrate according to [6] above, wherein the nitrogen gas flow rate ratio of the sputtering film - forming is 1 or more and 15 or less, and the oxygen gas flow rate ratio is 0.1 or more and 5 or less. [Advantages of the Invention]

[0011] The film - attached substrate having the silicide film of the present disclosure contains specific components, and by controlling the film - forming conditions, the physical properties of the silicide film are controlled. Therefore, since the absolute value of the average |TCR| in the temperature range from 40°C to 150°C is small, when used as a resistor, it shows a stable resistivity in any temperature band within the above - mentioned temperature range, and since it has excellent light transmittance, it can be applied to a high - precision image sensor. [Modes for Carrying Out the Invention]

[0012] Hereinafter, the present disclosure will be described in detail. However, the description of the constituent elements described below is an example of an embodiment of the present disclosure, and the present disclosure is not limited to these contents. Also, each configuration and parameter disclosed in this specification can be combined arbitrarily, and the upper and lower limits of the values disclosed in this specification can be combined arbitrarily. [Film - attached Substrate] This embodiment features a substrate with a chromium silicide film that contains chromium, silicon, nitrogen, and oxygen and has a film thickness of 300 nm or less. The substrate with the film can be used as a material for resistors.

[0013] The substrate with the film in this embodiment comprises a chromium silicide film and a substrate. The chromium silicide film is mainly composed of a compound of chromium (Cr) and silicon (Si). Since the chromium silicide film functions as a resistance film, the substrate with the film in this embodiment can be used as a resistor element. The chromium silicide film in the substrate with the film in this embodiment is a chromium silicide film containing chromium, silicon, nitrogen, and oxygen, that is, a nitrogen- and oxygen-containing chromium silicide film. In the substrate with the film in this embodiment, the increase in |TCR| is suppressed by the chromium silicide film containing nitrogen. On the other hand, the light transmittance is exhibited by containing oxygen, and since the bandgap of the chromium silicide film increases due to the chromium silicide film containing nitrogen and oxygen, the light transmittance tends to be high.

[0014] The substrate in the substrate with the film in this embodiment may be any substrate having light transmittance. Thereby, the substrate with the film in this embodiment can be applied not only to ordinary resistor elements but also to resistor elements that require optical properties such as image sensors. The substrate is preferably a substrate having an average total light transmittance of 80% or more, and more preferably a substrate having an average total light transmittance of 90% or more and 100% or less. Specific examples of the substrate in the substrate with the film in this embodiment include one or more selected from the group of glass substrates, sapphire substrates, and alumina substrates, and a glass substrate is preferred.

[0015] In this embodiment, the average total light transmittance is the average value of the total light transmittance obtained under the following conditions using a general spectrophotometer (for example, U-4100 manufactured by Hitachi High-Technologies Corporation). Light source: Halogen lamp Measurement wavelength: 400 nm to 800 nm Measurement interval: 5 nm

[0016] In the chromium silicide film of the film-attached substrate of the present embodiment, the film thickness is 300 nm or less. When the film thickness exceeds 300 nm, the surface resistance (Ω / □) per unit area (1 cm 2 ) becomes small and is not suitable for the resistor of the high-resistance portion. The film thickness of the chromium silicide film can be exemplified as 10 nm or more or 50 nm or more, and 150 nm or less or 120 nm or less. Since it is likely to be a thin film suitable for a resistor, the film thickness of the chromium silicide film is preferably 10 nm or more and 150 nm or less, or 50 nm or more and 120 nm or less.

[0017] The total content of chromium, silicon, nitrogen and oxygen in the chromium silicide film is 100 atm%, and further, the content of chromium is preferably 10 atom% or more and 30 atom% or less, the content of silicon is preferably 30 atom% or more and 60 atom% or less, the content of nitrogen is preferably 1 atom% or more and 40 atom% or less, and the content of oxygen is preferably 1 atom% or more and 10 atom% or less. Thereby, |TCR| is more likely to be lower.

[0018] The content of chromium is preferably 12 atom% or more and 20 atom% or less, and more preferably 14 atom% or more and 18 atom% or less.

[0019] The content of silicon is preferably 35 atom% or more and 55 atom% or less, and more preferably 40 atom% or more and 50 atom% or less.

[0020] The content of nitrogen is preferably 10 atom% or more and 38 atom% or less, and more preferably 20 atom% or more and 36 atom% or less.

[0021] The content of oxygen is preferably 2 atom% or more and 9 atom% or less, and more preferably 4 atom% or more and 8 atom% or less.

[0022] The chromium silicide film may further contain hydrogen as long as it exhibits its effects. The hydrogen content can be exemplified as 1 atom% or more and 10 atom% or less. When hydrogen is included, the total content of hydrogen, chromium, silicon, nitrogen, and oxygen is 100 atom%.

[0023] The chromium silicide film may contain metal impurities other than chromium and silicon as long as it exhibits its effects. Examples of the metal impurities include one or more selected from the group consisting of iron (Fe), aluminum (Al), and titanium (Ti). When metal impurities are included, the total content of the metal impurities, chromium, silicon, nitrogen, and oxygen is 100 atom%.

[0024] In the film-coated substrate of the present embodiment, the average |TCR| (hereinafter, also simply referred to as "average |TCR|") in the temperature range of 40°C to 150°C of the chromium silicide film is 0 ppm / °C or more and 30 ppm / °C or less. When the average |TCR| exceeds 30 ppm / °C, the change in resistivity due to temperature change becomes large, and the resistance characteristics become unstable when used as a sensor material. The smaller the value of the average |TCR|, the smaller the change in resistivity due to temperature change. Therefore, as the average |TCR| decreases, the change in resistance due to temperature change becomes smaller, enabling stable current supply and exhibiting high resistance characteristics. In order to exhibit more stable resistance characteristics against temperature change, the average |TCR| is preferably 0 ppm / °C or more and 15 ppm / °C or less, and more preferably 0 ppm / °C or more and 5 ppm / °C or less.

[0025] In the present embodiment, the average |TCR| is the arithmetic mean value of |TCR 40 | to |TCR 150 |. TCR (ppm / °C) is a value calculated by the following formula from the resistivity R (μΩ·cm) at each temperature, the resistivity R 30 (μΩ·cm), and the measurement temperature T (°C), and |TCR| is the absolute value of TCR.

[0026] TCR = (R - R 30 ) / (R 30 × (T - 30)) × 106 The "resistivity R at each temperature" refers to the resistivity at each measurement temperature of 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, or 150°C (the resistivity R at 30°C, etc. are also respectively referred to as "R 30 ", etc.).

[0027] The R of the chromium silicide film in the film - attached substrate of this embodiment 30 (μΩ·cm) is preferably 3000 μΩ·cm or more, 5000 μΩ·cm or more, 10000 μΩ·cm or more, or 15000 μΩ·cm or more. With such a resistivity, it can be applied to resistors in the high - resistance part. The resistivity R of the chromium silicide film 30 can be exemplified as 60000 μΩ·cm or less, 50000 μΩ·cm or less, or 45000 μΩ·cm or less. It is preferably 3000 μΩ·cm or more and 60000 μΩ·cm or less, and more preferably 5000 μΩ·cm or more and 50000 μΩ·cm or less.

[0028] The resistivity of the film can be measured by the van der pauw method using a Hall measurement system (for example, type 8403 AC / DC Hall measurement system, manufactured by Toyo Technica).

[0029] The film - attached substrate of this embodiment is a film - attached substrate in which a chromium silicide film is formed on a substrate showing light - transmission characteristics. On the other hand, when used as a conventional resistance element, it can also be a film - attached substrate in which a chromium silicide film is formed on a substrate that does not show light - transmittance characteristics, such as a ceramic substrate, a silicon substrate, a SiC substrate, a sapphire substrate, etc. [Manufacturing method of the film - attached substrate] The manufacturing method of the film - attached substrate of this embodiment can be arbitrary as long as it satisfies the above - mentioned configuration. As a preferable manufacturing method, there is a method for manufacturing a film - attached substrate, which includes a film - forming step of sputter - depositing a chromium silicide film on a substrate in an atmosphere containing nitrogen and oxygen using a sputtering target containing chromium and silicon (hereinafter, also simply referred to as "target"), and a heat - treatment step of heat - treating the film - attached substrate having the chromium silicide film. <Film - forming step> Through the film - forming step, a film - attached substrate having a chromium silicide film is obtained.

[0030] The target used in the film - forming step preferably has a composition that is 100% by mass of chromium and silicon, and more preferably has the same composition as the ratio of silicon to chromium in the chromium silicide in the film - attached substrate of this embodiment. Also, within the range where the effect is achieved, it may contain metal impurities other than chromium and silicon. Examples of the metal impurities include one or more selected from the group consisting of iron (Fe), aluminum (Al), and titanium (Ti).

[0031] The substrate used in the film - forming step includes one or more selected from the group consisting of a glass substrate, a sapphire substrate, and an alumina substrate, and a glass substrate is preferable.

[0032] The sputter - deposition can be performed by at least any one selected from the group consisting of a DC sputtering method, an RF sputtering method, an AC sputtering method, a DC magnetron sputtering method, an RF magnetron sputtering method, and an ion beam sputtering method. In terms of being able to deposit a film uniformly and at high speed on a large - area substrate, the sputter - deposition is preferably performed by a DC magnetron sputtering method or an RF magnetron sputtering method.

[0033] The power density is 0.6 W / cm 2 or more or 1.0 W / cm 2 or more, and 10 W / cm 2 or less or 7.5 W / cm 2The following can be exemplified. When the power density is 0.6 W / cm 2 or more, the film formation rate becomes high and the productivity is less likely to decrease. Also, when the power density is 10 W / cm 2 or less, the load on the target is small and the occurrence of defects in the target during sputtering film formation is suppressed. The power density is preferably 0.6 W / cm 2 or more and 10 W / cm 2 or less, more preferably 1.0 W / cm 2 or more and 7.5 W / cm 2 or less.

[0034] In the film formation step, a film is formed in an atmosphere containing nitrogen and oxygen, and argon gas, nitrogen gas, and oxygen gas are used as introduction gases. It is preferable that the nitrogen gas flow rate ratio (N2 / (Ar + N2 + O2)) is 1 or more and 15 or less, and the oxygen gas flow rate ratio (O2 / (Ar + N2 + O2)) is 0.1 or more and 5 or less. By having the nitrogen gas flow rate ratio within this range, a film with a small |TCR| can be manufactured. On the other hand, by having the oxygen gas flow rate ratio within this range, the optical properties can be improved.

[0035] The oxygen gas flow rate ratio and the nitrogen gas flow rate ratio can be calculated by measuring the flow rate (SCCM) of each gas and calculating the flow rate ratio of each gas from the ratio to the flow rate of the introduction gases (argon gas, nitrogen gas, and oxygen gas). The nitrogen gas flow rate ratio (N2 / (Ar + N2 + O2)) is more preferably 5 or more and 14 or less, and even more preferably 10 or more and 13 or less. The oxygen gas flow rate ratio (O2 / (Ar + N2 + O2)) is more preferably 0.3 or more and 3 or less, and even more preferably 0.5 or more and 2 or less. <Heat treatment step> The manufacturing method of this embodiment has a heat treatment step of heat-treating a film-coated substrate provided with a chromium silicide film. The chromium silicide film after film formation is amorphous, but it is considered that heat-treating this causes changes in crystallinity in minute regions such as the generation of crystal domains, and thereby, |TCR| can be reduced. If the heat treatment is not performed, |TCR| increases. The heat treatment temperature may be appropriately set according to the composition of the chromium silicide film, but it can be exemplified that it is 800°C or lower, or 700°C or lower. The lower limit of the heat treatment temperature can be exemplified as 150°C or higher, 200°C or higher, 300°C or higher, or 500°C or higher. When the heat treatment temperature is 800°C or lower, the production efficiency of the film is less likely to decrease. On the other hand, when the temperature of the heat treatment step is 150°C or higher, |TCR| tends to become small.

[0036] The heat treatment time may be appropriately adjusted according to the size and quantity of the film-coated substrate to be subjected to the treatment and the performance of the heat treatment furnace. For example, it can be exemplified that it is 0.5 hours or more and 10 hours or less.

[0037] The heat treatment is preferably performed in a non-oxygen atmosphere. The non-oxygen atmosphere is an atmosphere that does not contain oxygen. Specifically, for example, it includes at least any one selected from the group of a vacuum atmosphere, an argon atmosphere, and a nitrogen atmosphere. A vacuum atmosphere is more preferable, and a vacuum atmosphere of 10 Pa or less is even more preferable.

[0038] In the manufacturing method of this embodiment, it is preferable that the difference (△T) between the average total light transmittance of the obtained film-coated substrate and the average total light transmittance of the substrate to be subjected to the film formation step is 75% or less, 70% or less, or 65% or less. Although △T is preferably small, it can be exemplified as 5% or more, or 10% or more.

Example

[0039] Hereinafter, the present disclosure will be described by way of examples. However, the present disclosure is not limited thereto. (Film composition) The composition of the chromium silicide film was measured by an accelerator particle analyzer (device name: RBS-400 analytical end station, manufactured by Eurofins EAG). A sample with the film processed into a square shape of 10 mm × 10 mm × 0.7 mm was used as the measurement target. Measurement method: RBS method (Rutherford backscattering spectrometry)

[0040] (Film thickness) The film thickness of the chromium silicide film was measured by a film thickness step gauge (device name: Dektak, manufactured by Brucker). (Resistivity) The resistivity of the chromium silicide film was measured by the van der pauw method using a Hall measurement device (device name: 8403 type AC / DC Hall measurement system, manufactured by Toyo Technica). A sample with the film processed into a square shape of 10 mm × 10 mm × 0.7 mm was used as the measurement target.

[0041] (TCR and average |TCR|) The resistivity (μΩ·cm) of the chromium silicide film from 30°C to 150°C was measured at 10°C intervals using an 8403 type AC / DC Hall measurement system (manufactured by Toyo Technica) to obtain the resistivity R (R 30 to R 150 ). The resistivity R (μΩ·cm) at each temperature and 30 (μΩ·cm) and each temperature T (°C) were used to calculate the TCR in the range of 40°C to 150°C according to the following formula. TCR (ppm / °C) = (R - R 30 ) / (R 30 × (T - 30)) × 10 6 The average |TCR| was taken as the average value of the absolute values of the TCR values obtained in the range of 40°C to 150°C.

[0042] (Average total light transmittance and △T) The average total light transmittance of the substrate with the film and the substrate was taken as the average value of the total light transmittance obtained under the following conditions using a spectrophotometer (device name: U-4100, manufactured by HITACHI). Light source: Halogen lamp Measurement wavelength: 400 nm to 800 nm Measurement interval: 5 nm △T was determined from the difference obtained by subtracting the average total light transmittance of the film-coated substrate from the average total light transmittance of the substrate (91.7%).

[0043] (Example 1) <Fabrication of sputtering target> Chromium (Cr) flakes (purity: 99.99%, particle size: 2 - 3 mm) at 33 mass% and silicon (Si) flakes (purity: 99.999%, particle size: 10 mm) at 67 mass% were placed in a carbon crucible and melted at a melting temperature of 1600 °C to obtain a molten metal at 1600 °C. This was processed by the gas atomization method to obtain chromium silicide alloy powder. The obtained chromium silicide alloy powder was placed in a carbon crucible and hot-pressed under the following conditions for pressure sintering to obtain a chromium silicide sintered body. Firing method: Hot press Heating rate: 200 °C / hour Firing atmosphere: Vacuum (5 Pa or less) Firing temperature: 1250 °C Firing pressure: 20 MPa Firing time: 3 hours The obtained chromium silicide sintered body was processed into a sputtering target with a diameter of 4 inches.

[0044] <Film formation process> Using the obtained sputtering target, a film-coated substrate with a chromium silicide film was fabricated by sputtering film formation under the following conditions. Equipment: DC magnetron sputtering equipment (manufactured by ULVAC, Inc.) Magnetic field strength: 1000 Gauss (vertical component directly above the target) Distance between substrates: 90 mm Substrate temperature: Room temperature (about 25 °C) Introduced gases: Argon, nitrogen (N2), and oxygen (O2) Oxygen gas flow ratio: O2 / (Ar + N2 + O2) = 0.5 Nitrogen gas flow ratio: N2 / (Ar + N2 + O2) = 11 Substrate used: Glass substrate (manufactured by Corning Eagle XG) Thickness: 0.8 mm Sputtering power: 200 W (2.5 W / cm 2 )

[0045] <Heat treatment process> The obtained film-coated substrate was heat-treated under the following conditions to produce a film-coated substrate provided with a chromium silicide film of this example. Heat treatment temperature: 680 °C Heat treatment time: 60 minutes Heat treatment atmosphere: Vacuum (5 Pa or less) In the film-coated substrate of this example, the Cr content of the chromium silicide film was 15 atom%, the Si content was 46 atom%, the N content was 32 atom%, the O content was 5 atom%, and the H content was 2 atom%. (Example 2) A film-coated substrate provided with a chromium silicide film was produced under the same conditions as in Example 1, except that the oxygen gas flow rate ratio during sputtering film formation was 0.7. (Example 3) A film-coated substrate provided with a chromium silicide film was produced under the same conditions as in Example 1, except that the oxygen gas flow rate ratio during sputtering film formation was 0.8. (Example 4) A film-coated substrate provided with a chromium silicide film was produced under the same conditions as in Example 1, except that the oxygen gas flow rate ratio during sputtering film formation was 0.8 and the heat treatment temperature was 690 °C. (Example 5) Chromium (Cr) flakes and silicon (Si) flakes were weighed so that the chromium (Cr) flakes were 42% by mass and the silicon (Si) flakes were 58% by mass, and these were mixed. A film-coated substrate provided with a chromium silicide film was produced under the same conditions as in Example 1, except that the oxygen gas flow rate ratio was 1.0 and the heat treatment temperature was 590 °C. (Comparative Example 1) A film-coated substrate provided with a chromium silicide film was produced under the same conditions as in Example 1, except that the introduced gases were argon and nitrogen (oxygen gas flow rate ratio = 0). (Comparative Example 2) Chromium (Cr) flakes and silicon (Si) flakes were weighed so that the chromium (Cr) flakes were 42% by mass and the silicon (Si) flakes were 58% by mass, and they were mixed. A substrate with a chromium silicide film was produced under the same conditions as in Example 1 except that the introduced gas was argon and nitrogen (oxygen gas flow rate ratio = 0), and the heat treatment temperature was 580°C.

[0046] The evaluation results of the examples and comparative examples are shown in Table 1.

[0047]

Table 1

[0048] The film thicknesses of the films obtained in the examples were all 100.5 ± 7.5 nm (minimum: 93 nm, maximum: 108 nm) and had equivalent film thicknesses. From the examples and comparative examples, it was confirmed that the resistivity increased by making the film obtained by flowing oxygen gas, that is, a film containing oxygen. Also, from Examples 1 to 3, it was confirmed that as the oxygen gas flow rate ratio increased, that is, as the oxygen concentration in the film increased, the resistivity increased and the average total light transmittance increased. Furthermore, from Examples 3 and 4, it was confirmed that as the heat treatment temperature increased, the average |TCR| decreased.

Claims

1. A substrate with a film, comprising: a chromium silicide film containing chromium, silicon, nitrogen, and oxygen and having a film thickness of 300 nm or less; and a substrate.

2. The substrate with a film according to Claim 1, wherein the total content of chromium, silicon, nitrogen, and oxygen in the chromium silicide film is 100 atm%, and the content of chromium is 10 atom% or more and 30 atom% or less, the content of silicon is 30 atom% or more and 60 atom% or less, the content of nitrogen is 1 atom% or more and 40 atom% or less, and the content of oxygen is 1 atom% or more and 10 atom% or less.

3. The substrate with a film according to Claim 1 or Claim 2, wherein the substrate has an average total light transmittance of 80% or more.

4. The substrate with a film according to Claim 1 or Claim 2, wherein the average |TCR| of the chromium silicide film in the temperature range from 40°C to 150°C is 0 ppm / °C or more and 30 ppm / °C or less.

5. The substrate with a film according to Claim 1 or Claim 2, wherein the resistivity of the chromium silicide film at 30°C is 3000 μΩ·cm or more.

6. A method for manufacturing a substrate with a film according to Claim 1 or Claim 2, comprising: a film forming step of sputter-forming a chromium silicide film on a substrate in an atmosphere containing nitrogen and oxygen using a sputtering target containing chromium and silicon; and a heat treatment step of heat-treating the substrate with a film having the chromium silicide film.

7. The method for manufacturing a substrate with a film according to Claim 6, wherein the nitrogen gas flow rate ratio in the sputter film formation is 1 or more and 15 or less, and the oxygen gas flow rate ratio is 0.1 or more and 5 or less.

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