JP2006222390A - Capacitor, manufacturing method therefor, and filter using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a capacitor capable of improving adhesion between a dielectric layer and a lower electrode while increasing electrostatic capacity, a method for manufacturing the capacitor, and a filter using the capacitor. <P>SOLUTION: The capacitor 10 includes a lower electrode 14A, a dielectric layer 16 having a SiO<SB>2</SB>layer 20 formed on the lower electrode 14A and an Si<SB>3</SB>N<SB>4</SB>layer 22 formed on the SiO<SB>2</SB>layer 20 and an upper electrode 14B formed on the dielectric layer 16. Since the SiO<SB>2</SB>layer 20 is formed between the lower electrode 14A and the Si<SB>3</SB>N<SB>4</SB>layer 22, the lower electrode 14A is firmly stuck to the Si<SB>3</SB>N<SB>4</SB>layer 22 as compared with a conventional capacitor where the Si<SB>3</SB>N<SB>4</SB>layer 22 is directly formed on the lower electrode 14A. Namely, the invented capacitor 10 has large electrostatic capacity because the dielectric layer 16 is provided with the Si<SB>3</SB>N<SB>4</SB>layer 22 having a high dielectric constant, and improves adhesion between the dielectric layer 16 and the lower electrode 14A as compared with the conventional capacitor. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a capacitor having a thin film dielectric layer, a manufacturing method thereof, and a filter using the same.

Conventionally, the dielectric layer which comprises the capacitor in the field | area of this technique is disclosed by the following patent document 1, for example. This publication discloses that silicon nitride (Si ₃ N ₄ ) is used for an insulating film functioning as a dielectric layer of a capacitor. Such a metal nitride typified by Si ₃ N ₄ is suitable for the dielectric layer of the capacitor because of its high dielectric constant. Therefore, by forming the dielectric layer with this metal nitride, the capacitance of the capacitor can be increased compared to the case where the dielectric layer is formed with a metal oxide such as SiO ₂ which has been widely used conventionally. Can do.
Japanese Patent Laid-Open No. 11-8359

  However, it is known that this metal nitride layer generally has a larger film stress generated during film formation than the metal oxide layer. Therefore, when a dielectric layer is formed on the surface of the lower electrode, the dielectric layer is not sufficiently adhered to the lower electrode, and the dielectric layer is peeled off from the lower electrode in subsequent annealing treatment, ultrasonic cleaning, etc. was there.

  Accordingly, the present invention has been made to solve the above-described problem, and a capacitor in which the adhesion between the dielectric layer and the lower electrode is improved while increasing the capacitance, and a manufacturing method thereof, and An object of the present invention is to provide a filter using the.

  A capacitor according to the present invention includes a dielectric layer having a lower electrode, a metal oxide layer formed on the lower electrode, and a metal nitride layer formed on the metal oxide layer, and a dielectric layer on the dielectric layer. And an upper electrode formed.

  In this capacitor, a metal oxide layer as a dielectric layer is formed on the lower electrode. A metal nitride layer is formed on the metal oxide layer. When the metal oxide layer is interposed between the lower electrode and the metal nitride layer in this manner, the lower electrode and the metal nitride are compared with the case where the metal nitride layer is directly formed on the lower electrode as in the conventional capacitor. The material layer adheres firmly. That is, the capacitor according to the present invention has a large capacitance because the dielectric layer includes a metal nitride layer having a high dielectric constant, and has a lower dielectric layer and lower portion than the conventional capacitor. The adhesion between the electrodes is improved.

  Moreover, it is preferable that the metal which comprises a metal oxide layer, and the metal which comprises a metal nitride layer are the same. In this case, for example, when a metal oxide layer and a metal nitride layer are formed by sputtering, these layers can be formed by using only one metal target, so that labor and time for manufacturing a capacitor can be reduced.

  Moreover, it is preferable that the metal which comprises a metal oxide layer and a metal nitride layer is Si or Al. In this case, practical element characteristics can be obtained while the metal is easily available.

  Moreover, it is preferable that the constituent material of a lower electrode contains at least 1 type of material in the group which consists of Cu, Ag, Ni, W, Mo, Ti, Cr, Al. In this case, the lower electrode is firmly adhered to the metal nitride layer by the metal oxide layer interposed between the lower electrode and the metal nitride layer.

  The filter according to the present invention includes a dielectric layer having a lower electrode, a metal oxide layer formed on the lower electrode, and a metal nitride layer formed on the metal oxide layer, and a dielectric layer on the dielectric layer. A capacitor including the formed upper electrode is provided.

  In this filter, a metal oxide layer as a dielectric layer is formed on the lower electrode of the capacitor. A metal nitride layer is formed on the metal oxide layer. When the metal oxide layer is interposed between the lower electrode and the metal nitride layer in this manner, the lower electrode and the metal nitride are compared with the case where the metal nitride layer is directly formed on the lower electrode as in the conventional capacitor. The material layer adheres firmly. That is, the capacitor of the filter of the present invention has a large capacitance because the dielectric layer includes a metal nitride layer having a high dielectric constant, and has a dielectric layer that is larger than that of a conventional capacitor. Adhesion with the lower electrode is improved.

  The method for manufacturing a capacitor according to the present invention includes forming a metal oxide layer on the lower electrode, forming a metal nitride layer on the metal oxide layer, and having the metal oxide layer and the metal nitride layer. The method includes a step of forming a dielectric layer and a step of forming an upper electrode on the dielectric layer.

  In this capacitor manufacturing method, a metal oxide layer as a dielectric layer is formed on the lower electrode, and a metal nitride layer is formed on the metal oxide layer. When the metal oxide layer is interposed between the lower electrode and the metal nitride layer in this manner, the lower electrode and the metal nitride are compared with the case where the metal nitride layer is directly formed on the lower electrode as in the conventional capacitor. The material layer adheres firmly. That is, when the capacitor manufacturing method according to the present invention is used, the dielectric layer is a large-capacitance capacitor including a metal nitride layer having a high dielectric constant, and the dielectric layer and the lower portion of the capacitor are lower than the conventional capacitor. A capacitor having high adhesion between the electrodes can be obtained.

  In addition, a metal oxide layer and a metal nitride layer are formed by sputtering, and when the metal oxide layer is formed by sputtering, a metal target is sputtered in a gas atmosphere containing oxygen gas to form a metal nitride layer. During the sputtering film formation, it is preferable that the metal target used for the sputtering film formation of the metal oxide layer is sputtered in a gas atmosphere containing nitrogen gas. In this case, since the metal oxide layer and the metal nitride layer are formed with only one metal target, labor and time for manufacturing the capacitor can be reduced.

  According to the present invention, there are provided a capacitor in which the adhesion between the dielectric layer and the lower electrode is improved while increasing the capacitance, a method for manufacturing the capacitor, and a filter using the capacitor.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a capacitor, a method for manufacturing the same, and a form that is considered to be the best for carrying out a filter using the same will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected about the same or equivalent element, and the description is abbreviate | omitted when description overlaps.

  FIG. 1 is a schematic cross-sectional view illustrating a capacitor according to an embodiment of the present invention. The capacitor 10 has a thin film laminated structure including a substrate 12, a pair of electrode pairs 14A and 14B for applying a voltage to the capacitor 10, and a dielectric layer 16 interposed between the electrode pairs 14A and 14B. is doing.

The substrate 12 is made of Al ₂ O ₃ , and the surface may be coated with an Al ₂ O ₃ thin film as appropriate in order to improve flatness. In addition, the constituent material of the board | substrate 12 can be changed into Si etc., for example.

  Of the pair of electrodes 14A and 14B, an electrode (hereinafter referred to as a lower electrode) 14A closer to the substrate 12 is plated through a Cu seed layer 18A formed on the surface 12a of the substrate 12 by sputtering. It is made of Cu.

On this lower electrode 14A, a SiO ₂ layer 20 (thickness: 10 nm) and a Si ₃ N ₄ layer 22 (thickness: 100 nm) constituting the dielectric layer 16 are sequentially laminated. The SiO ₂ layer 20 is made of amorphous SiO ₂ , and the Si ₃ N ₄ layer 22 is also made of amorphous Si ₃ N ₄ . Note that the thickness (D1) of the SiO ₂ layer 20 is not limited to 10 nm, and may be appropriately changed within a range of 5 nm ≦ D1 ≦ 15 nm. Certainly it is difficult to perform the insulation by the SiO ₂ layer 20 when the thickness D1 of the SiO ₂ layer 20 is thinner than 5 nm, the capacitor characteristic of the practical level can be obtained if the thickness D1 is larger than 15nm Absent. Further, the thickness (D2) of the Si ₃ N ₄ layer 22 is not limited to 100 nm, and may be appropriately changed.

  On the dielectric layer 16, an electrode (hereinafter referred to as an upper electrode) 14 </ b> B far from the substrate 12 in the electrode pair 14 </ b> A, 14 </ b> B is formed. The upper electrode 14B is formed by plating through an Au seed layer 18B formed by sputtering on the dielectric layer 16, and is made of Au.

  Next, a sputtering apparatus used when manufacturing the capacitor 10 will be described with reference to FIG. FIG. 2 is a partially cutaway perspective view showing a sputtering apparatus according to an embodiment of the present invention. The sputtering apparatus 30 is a high-frequency sputtering film forming apparatus.

  The sputtering apparatus 30 includes a chamber 32, a substrate holder 34 provided in the vicinity of the lower end portion in the chamber 32, and a target support plate 36 provided in the vicinity of the upper end portion in the chamber 32.

  A target holder 38 is fixed to the target support plate 36, and a metal target 40 is attached to the target holder 38. Si is used for the metal target 40. A shutter (not shown) is provided so as to face the metal target 40, and is opened and closed as necessary.

  The substrate holder 34 is disc-shaped, and the substrate 12 on which the lower electrode 14A is formed is placed on the upper surface 34a. The substrate 12 faces the target support plate 36, and the dielectric layer 16 is formed on the lower electrode 14 </ b> A of the substrate 12 by sputtering the metal target 40 attached to the target support plate 36.

  A vacuum pump 44 is attached to the chamber 32 via a pipe 42, and the inside of the chamber 32 can be appropriately evacuated by opening and closing the valve 42a of the pipe 42. Further, the chamber 32 is provided with three gas pipes 46A, 46B, 46C for introducing atmospheric gas into the chamber 32 and an exhaust pipe 48 used for exhaust.

  Nitrogen gas, oxygen gas, and argon gas are introduced from the gas pipes 46A, 46B, and 46C, and the flow rate is controlled by valves (for example, electromagnetic valves) 50A, 50B, and 50C provided in the middle thereof.

In the sputtering apparatus 30, a predetermined gas is selectively introduced from the three gas pipes 46 </ b> A, 46 </ b> B, 46 </ b> C and the atmosphere in the chamber is adjusted, and the target support plate 36 and the substrate holder 34 are interposed. The metal target 40 is sputtered by applying a high frequency voltage. More specifically, when sputtering is performed by introducing oxygen gas and argon gas into the chamber 32, a SiO ₂ layer is formed on the substrate 12, and nitrogen gas and argon gas are introduced into the chamber 32 for sputtering. As a result, a Si ₃ N ₄ layer is formed on the substrate 12. Thus, both the SiO ₂ layer and the Si ₃ N ₄ layer are formed by changing the atmospheric gas in the chamber 32 without changing the metal target 40 (that is, using one metal target). Therefore, the dielectric layer 16 described above can be easily formed by using the sputtering apparatus 30.

  Next, a procedure for manufacturing the above-described capacitor 10 will be described with reference to FIG. 3A to 3E are diagrams sequentially illustrating a procedure for manufacturing the capacitor 10.

  When manufacturing the capacitor 10, first, the substrate 12 shown in FIG. 3A is prepared, and a Cu seed layer 18A is formed on the upper surface 12a of the substrate 12 by sputtering, and Cu is formed on the Cu seed layer 18A. The lower electrode 14A is formed by plating (see FIG. 3B). The lower electrode 14A may be subjected to chemical mechanical polishing (CMP) as necessary.

Next, the substrate 12 on which the lower electrode 14A is formed is loaded on the substrate holder 34 of the sputtering apparatus 30 described above, and the inside of the chamber 32 is a mixed gas of oxygen gas and argon gas introduced from the gas pipes 46B and 46C. After the atmosphere, the metal target 40 is sputtered to form the SiO ₂ layer 20 on the upper surface of the lower electrode 14A (see FIG. 3C). After the formation of the SiO ₂ layer 20, the mixed gas is exhausted from the exhaust pipe 48, and then the inside of the chamber 32 is changed to a mixed gas atmosphere of nitrogen gas and argon gas introduced from the gas pipes 46 A and 46 C, and then the metal target. 40 is sputtered to form the Si ₃ N ₄ layer 22 on the upper surface of the SiO ₂ layer 20 (see FIG. 3D).

After forming the dielectric layer 16 composed of the SiO ₂ layer 20 and the Si ₃ N ₄ layer 22 as described above, the substrate 12 is taken out from the sputtering apparatus 30 and an Au seed layer is formed on the upper surface of the Si ₃ N ₄ layer 22. 18B is formed by sputtering, and the upper electrode 14B is formed by plating on the Au seed layer 18B, thereby completing the production of the capacitor 10 (see FIG. 3E).

As described above, a part of the dielectric layer 16 of the capacitor 10 is composed of the Si ₃ N ₄ layer 22. It is generally known that such a metal nitride layer such as the Si ₃ N ₄ layer 22 increases the capacitance of the capacitor compared to the metal nitride layer such as the SiO ₂ layer 20. Therefore, this dielectric layer 16 has a larger electrostatic capacity than a dielectric layer composed of only a metal oxide layer.

Then, when the inventors directly formed the Si ₃ N ₄ layer 22 of the dielectric layer 16 having a large film stress on the lower electrode 14A, the SiO ₂ layer which is a metal oxide layer having a smaller film stress. by interposing the 20 new that as compared with the case of forming directly the _Si 3 _{N 4} layer 22 on the lower electrode 14A, the adhesion between the top of the _Si 3 _{N 4} layer 22 and the lower electrode 14A is increased I found it. That is, prior to the formation of the Si ₃ N ₄ layer 22 of the dielectric layer 16, the SiO ₂ layer 20 constituting a part of the dielectric layer 16 is formed on the lower electrode 14 A, so that the dielectric layer 16 and The lower electrode 14A is firmly attached. Therefore, in the capacitor 10, the situation where the dielectric layer 16 is peeled off from the lower electrode 14A is significantly suppressed in the annealing process or ultrasonic cleaning performed after the formation of the dielectric layer 16.

Further, the SiO ₂ layer 20 and the Si ₃ N ₄ layer 22 of the dielectric layer 16 are both composed of the same Si. When the SiO ₂ layer 20 and the Si ₃ N ₄ layer 22 are formed by sputtering using the sputtering apparatus 30 described above, these layers can be formed by using only one metal target 40. That is, if the metal target 40 is sputtered in a mixed gas atmosphere of oxygen gas and argon gas, the SiO ₂ layer 20 is formed, and the metal target 40 used for the sputtering film formation of the SiO ₂ layer 20 is replaced with nitrogen gas and argon. If sputtering is performed in a mixed gas atmosphere with a gas, the Si ₃ N ₄ layer 22 is formed. Therefore, it is not necessary to change the metal target each time the films 20 and 22 are formed, and labor and time for manufacturing the capacitor 10 are reduced. The metal target 40 may be made of Al in addition to Si in that a metal can be easily obtained and practical device characteristics can be obtained. When the metal target 40 is made of Al, a capacitor in which an Al ₂ O ₃ layer is formed instead of the SiO ₂ layer 20 and an AlN layer is formed instead of the Si ₃ N ₄ layer 22 is obtained.

Here, since the lower electrode 14A is made of Cu that is easily oxidized, the adhesion between the lower electrode 14A and the Si ₃ N ₄ layer 22 is likely to deteriorate, but the lower electrode 14A and the Si ₃ N ₄ By interposing the SiO ₂ layer 20 with the layer 22, the adhesion between the dielectric layer 16 and the lower electrode 14A is effectively improved. In other words, the lower electrode 14A is firmly adhered to the Si ₃ N ₄ layer 22 by the SiO ₂ layer 20 interposed between the lower electrode 14A and the Si ₃ N ₄ layer 22. The constituent material of the lower electrode 14A includes at least one material selected from the group consisting of Cu, Ag, Ni, W, Mo, Ti, Cr, and Al as long as it is a material that is easily oxidized like Cu. It may be.

  The capacitor 10 described above can be applied to various filters as shown in FIG. 4, for example. FIG. 4 is a diagram illustrating an example of a filter to which the capacitor 10 is applied. FIG. 4A illustrates a low-pass filter, and FIG. 4B illustrates a high-pass filter. That is, each of the low-pass filter 60A shown in FIG. 4A and the high-pass filter 60B shown in FIG. 4B includes one inductor (L), one capacitor (C), and one resistor (R). The capacitor 10 described above is used as the capacitor. That is, such a filter 60A, 60B has a large electrostatic capacity by adopting the capacitor 10, and in the capacitor 10, the dielectric layer 16 and the lower electrode 14A are firmly adhered. Although a filter having a simple configuration is shown in FIG. 4, the capacitor 10 can be applied to various types of filters including one or more of L, C, and R.

  The present invention is not limited to the above embodiment, and various modifications are possible. For example, the capacitor does not necessarily include a substrate and may be removed as appropriate. The sputtering apparatus used for forming the dielectric layer is not limited to a high-frequency sputtering system, and a known sputtering system such as an ECR sputtering system can be used.

1 is a schematic cross-sectional view illustrating a capacitor according to an embodiment of the present invention. FIG. 2 is a partially cutaway perspective view showing a sputtering apparatus used for manufacturing the capacitor shown in FIG. 1. It is the figure which showed the procedure which produces the capacitor shown in FIG. It is the figure which showed the example of the filter to which the capacitor shown in FIG. 1 was applied.

Explanation of symbols

10 ... capacitor, 12 ... substrate, 14A ... lower electrode, 14B ... upper electrode, 16 ... dielectric layer, 20 ... SiO ₂ layer, 22 ... _Si 3 _{N 4} layer, 30 ... sputtering apparatus, 40 ... metal target, 60A, 60B: Filter.

Claims (7)

A lower electrode;
A dielectric layer having a metal oxide layer formed on the lower electrode and a metal nitride layer formed on the metal oxide layer;
A capacitor comprising an upper electrode formed on the dielectric layer.   The capacitor according to claim 1, wherein a metal constituting the metal oxide layer and a metal constituting the metal nitride layer are the same.   The capacitor according to claim 2, wherein a metal constituting the metal oxide layer and the metal nitride layer is Si or Al.   The constituent material of the said lower electrode contains at least 1 sort (s) of material in the group which consists of Cu, Ag, Ni, W, Mo, Ti, Cr, Al. Capacitor.   A dielectric layer having a lower electrode, a metal oxide layer formed on the lower electrode, and a metal nitride layer formed on the metal oxide layer; and an upper portion formed on the dielectric layer A filter comprising a capacitor comprising an electrode. Forming a metal oxide layer on the lower electrode and forming a metal nitride layer on the metal oxide layer to form a dielectric layer having the metal oxide layer and the metal nitride layer; When,
Forming a top electrode on the dielectric layer. Forming the metal oxide layer and the metal nitride layer by sputtering;
During the sputter deposition of the metal oxide layer, a metal target is sputtered in a gas atmosphere containing oxygen gas,
7. The capacitor according to claim 6, wherein when the metal nitride layer is formed by sputtering, the metal target used for the sputtering formation of the metal oxide layer is sputtered in a gas atmosphere containing nitrogen gas. 8. Production method.

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