JP2007103548A - Thin film resistive element and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a crack of the resistive film formed on an electrode and an insulating layer in a thin film resistive element. <P>SOLUTION: The thin film resistive element comprises a substrate; an insulating layer formed on the substrate; an electrode formed on the substrate or on the insulating layer; a passivation layer formed so as to eliminate the level difference between the electrode and the insulating layer, or the discontinuous part generated to the portion wherein the electrode and the insulating layer come into contact; and a resistance thin film formed on the passivation layer and the electrode. The level difference or the discontinuous part is canceled by the passivation layer so that cracks may be prevented by alleviating adverse effect on the resistance thin film. Further, a taper may be formed at the end of the passivation layer. By this way, as the level difference is not formed by the passivation layer, the adverse effect is reduced on the resistance thin film. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a technique for preventing cracking of a resistive thin film formed on an electrode and an insulating layer in a thin film resistive element.

As the resistance material in the thin film resistance element, Ta-based oxides or nitrides such as Ta, TaSiN, TaSiO, or cermet materials such as M (metal) -SiO / SiN are generally used. Further, a thin film resistor element is formed using Al, Au, or Pt used for a semiconductor wiring material as an electrode material and SiO ₂ as an insulating layer. In general, in order to form a high-resistance thin film element, it is necessary to select a material having a high resistivity as a resistance material, or to reduce the element size or reduce the film thickness.

For example, Japanese Patent Application Laid-Open No. 2004-327868 discloses a structure as shown in FIG. That is, a structure is disclosed in which a Pt electrode 103 is formed on a Si substrate 101 with a SiO ₂ insulating layer 102 by dry etching, and a thin film resistance film 104 is formed and processed thereon. Therefore, a step 105 of several hundred nm is generated between the Pt electrode 103 and the SiO ₂ insulating layer 102, and there is a problem that the thin film resistance film 104 is easily cracked by the step 105. Further, when the resistance material is thinned for the purpose of increasing the resistance, there is a possibility that the thin film resistance film 104 is disconnected at the end of the Pt electrode 103, and it is difficult to make it thinner than the Pt electrode 103.

FIG. 2 shows the structure of another conventional thin film resistance element. As shown in FIG. 2, a Cu electrode 112 and an insulating film 111 made of SiO ₂ or BCB (benzocyclobutene) are formed on a Si substrate 110, and a thin film resistance film 113 is formed and processed thereon. It has become. A Cu / SiO ₂ structure or a Cu / BCB structure composed of the electrode 112 and the insulating film 111 as shown in FIG. 2 is formed by a damascene process capable of forming them in a submicron order. Even in the thus formed Cu / SiO ₂ structure or Cu / BCB structure, cracks may also occur in the thin-film resistance film 113 due to cracks generated at the boundary portion 114 between the electrode and the insulating film. Further, a step due to dishing may occur in the boundary portion 114 or the like.
JP 2004-327868 A

  As described above, the conventional thin film resistance element has a problem that a crack occurs in the thin film resistance film itself due to a step between the base electrode and the insulating layer or a crack between the electrode and the insulating layer.

  Accordingly, an object of the present invention is to provide a novel technique for preventing cracking of a resistance film formed on an electrode and an insulating layer in a thin film resistance element.

  The thin film resistance element according to the present invention includes a substrate, an insulating layer formed on the substrate, an electrode formed on the substrate or the insulating layer, a step between the electrode and the insulating layer, or an electrode and the insulating layer in contact with each other. A passivation layer formed so as to eliminate a discontinuous portion generated in the portion; and a resistance thin film formed on the passivation layer and the electrode. The passivation layer eliminates steps or discontinuities, suppresses the influence on the resistance thin film, and prevents cracks.

  Note that the end portion of the passivation layer may be tapered. This is because the step is not formed by the passivation layer and the influence on the resistance thin film is suppressed.

  Furthermore, the passivation layer may be an organic insulating layer. The organic insulating layer is formed of, for example, polyimide or BCB.

  A first thin film resistance element manufacturing method according to the present invention includes a step of forming an insulating layer on a substrate, a step of forming an electrode on the insulating layer, and a passivation layer so as to eliminate a step between the electrode and the insulating layer. Forming a passivation layer and forming a resistance thin film on the passivation layer and the electrode. If the step is eliminated, cracks are less likely to occur, so that a thinner resistive thin film can be formed.

  Further, the passivation layer forming step may include a step of processing the end portion of the passivation layer so as to be tapered. The influence of the passivation layer on the resistive thin film can be suppressed.

  In the second thin film resistor element manufacturing method according to the present invention, a step of forming an insulating layer and an electrode on a substrate, and a discontinuity formed at a step between the electrode and the insulating layer or a portion where the electrode and the insulating layer are in contact with each other are filled. Forming a passivation layer for forming a passivation layer, and forming a resistive thin film on the passivation layer and the electrode. If such a step or discontinuous portion is planarized by a passivation layer, a resistive thin film can be stably formed in the upper layer.

  In addition, the passivation layer forming step may include a step of forming the passivation layer by spin coating.

  ADVANTAGE OF THE INVENTION According to this invention, the crack of the resistance thin film formed on an electrode and an insulating layer can be prevented in a thin film resistance element.

The structure of the thin film resistance element according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 3A shows a top view of the thin film resistance element according to the first embodiment. In FIG. 3A, an SiO ₂ insulating film 11, a Cu electrode 12, an organic insulating film (passivation film) 15, and a resistive thin film 13 are formed in this order on a Si substrate 10 (not shown). FIG. 3B shows a cross section along AA ′ in FIG. An organic insulating film 15 is formed as a passivation film that covers the discontinuity or step. As shown in FIG. 3B, the Cu electrode 12 is divided into two electrodes 12a and 12b, and the SiO ₂ insulating film 11 is also formed between these electrodes 12a and 12b. Then, the boundary portion 14 between the Cu electrode 12a or 12b and the SiO ₂ insulating film 11 employs a structure to be protected by an organic insulating film 15 formed by spin coating. Although it looks flat in FIG. 3B, the boundary portion 14 has a discontinuity or a step at a portion where the upper surface of the electrode 12a or 12b and the upper surface of the SiO ₂ insulating film 11 meet. Specifically, the upper end portion of the Cu electrode 12a on the Cu electrode 12b side, the upper portion of the SiO ₂ insulating film 11 between the Cu electrode 12a and the Cu electrode 12b, the upper end portion of the Cu electrode 12b on the Cu electrode 12a side, Thus, the organic insulating film 15 is formed. Further, the upper ends of both ends of the organic insulating film 15 are tapered. Further, a resistive thin film 13 is formed on a part of the electrodes 12 a and 12 b and on the organic insulating film 15.

  In this way, by passivating the discontinuities and steps in the electrode-insulating film boundary portion 14, the electrode and insulating film, which are the underlying layers on which the resistive thin film is formed, become continuous, on the submicron order. Flattened. Therefore, the resistance thin film 13 is not cracked. In addition, since the resistive thin film is formed on the structurally stable passivation layer, it is possible to form a stable thin film resistive element in terms of adhesion and strength.

Note that the Cu electrode 12 may be formed of Al, Au, or the like. The SiO ₂ insulating film 11 may be an inorganic insulating film such as SiN, and an organic insulating film such as polyimide or BCB. Further, the resistance thin film 13 may be TaN, TaSiN, or a cermet resistance film.

Next, an example of a method for manufacturing the thin film resistance element shown in FIGS. 3A and 3B will be described with reference to FIGS. First, as shown in FIG. 4A, a layer including the SiO ₂ insulating film 11 and the Cu electrodes 12a and 12b is formed on the Si substrate 10.

Next, as shown in FIG. 4B, in order to protect the boundary portion 14 between the electrode 12a or 12b and the SiO ₂ insulating film 11, an organic insulating film 15 is formed. At this time, by using a spin coating method, it is possible to form the organic insulating film 15 that becomes a passivation film without dragging the cracks or steps in the boundary portion 14. Further, the organic insulating film 15 formed on the Cu electrodes 12a and 12b is controlled by controlling the taper angles of the tapered portions 14a and 14b on the organic insulating film 15 by selecting a material that can be processed by photolithography. It becomes possible to do. The taper angles of the tapers 14a and 14b of the organic insulating film 15 are preferably gentle in order to suppress the occurrence of cracks in the resistive thin film 13 on the ends of the Cu electrodes 12a and 12b.

  Next, as shown in FIG. 4C, lift-off resists 16 and 17 for processing the resistive thin film 13 are patterned. This process is the same as in the prior art and will not be described further. Thereafter, as shown in FIG. 4D, the resistive thin film 13 is formed and processed by sputtering or the like. Further, the lift-off resists 16 and 17 are removed. By doing so, the thin film resistance element shown in FIGS. 3A and 3B is formed.

FIG. 5 shows the structure of the thin film resistor element according to the second embodiment. In the thin film resistance element according to the second embodiment, a SiO ₂ insulating layer 22 is formed on a Si substrate 21. In addition, Pt electrodes 23 a and 23 b are formed on the SiO ₂ insulating layer 22. Further, an organic insulating film 25 is formed between the Pt electrodes 23a and 23b. The organic insulating film 25 is formed slightly higher than the Pt electrodes 23a and 23b, and the left and right upper end portions 25a and 25b adjacent to the Pt electrodes 23a and 23b are part of the Pt electrodes 23a and 23b. It is covered and processed to have a gentle taper angle. A resistive thin film 24 is formed on the organic insulating layer 25 and a part of the Pt electrodes 23a and 23b.

By adopting such a structure, the step between the Pt electrodes 23a and 23b and the SiO ₂ insulating layer 22 is eliminated, so that the resistance thin film 24 is not cracked.

Next, the formation process of the thin film resistance element having the structure shown in FIG. 5 will be described with reference to FIGS. First, as shown in FIG. 6A, the SiO ₂ insulating layer 22 and the Pt electrodes 23a and 23b are formed on the Si substrate 21.

Then, as shown in FIG. 6B, the organic insulating film 25 is patterned so as to fill the step between the Pt electrodes 23a and 23b and the SiO ₂ insulating layer 22. A material that can be processed by photolithography is selected for the organic insulating film 25. Then, the left and right upper end portions 25a and 25b of the organic insulating film 25 adjacent to the Pt electrodes 23a and 23b cover a part of the Pt electrodes 23a and 23b from the top, and against the Pt electrodes 23a and 23b. The shape is controlled so as to have a gentle taper angle.

  Next, as shown in FIG. 6C, lift-off resists 26 and 27 for processing the resistive thin film 24 are patterned. Since this process is the same as the prior art, it will not be described further. Thereafter, as shown in FIG. 6D, the resistive thin film 24 is formed and processed by a sputtering method or the like. Then, the lift-off resists 26 and 27 are removed.

  Also in the structure as shown in FIG. 6D, the effect of the step between the base electrode and the insulating layer is absorbed by the organic insulating film 25, so that the resistive thin film 24 does not crack.

  FIG. 7 shows a scanning electron micrograph of the cross section of the conventional structure shown in FIG. In FIG. 7, a crack 34 and a step 35 are formed in the Cu electrode 31, the BCB insulating film 32, and the resistance thin film 33, and the crack 36 was confirmed in the resistance thin film 33 by dragging the influence of the base. On the other hand, in the passivation structure according to the present embodiment shown in FIG. 3 in FIG. 8, since the Cu electrode 31 and the BCB insulating layer 32 are passivated by the BCB insulating film 37, no crack is observed in the resistive thin film 33. It was confirmed that the resistance element was well formed.

  Although the embodiment of the present invention has been described above, the present invention is not limited to this. For example, an example in which two electrodes are arranged in parallel is shown, but the relationship between the electrodes is not limited to this. In addition, when a step or a discontinuous portion is generated between the electrode and the insulating layer, the present invention can be applied to prevent a crack or the like from occurring in the upper layer.

It is a figure showing the structure of the thin film resistive element which concerns on a 1st prior art. It is a figure showing the structure of the thin film resistive element which concerns on a 2nd prior art. (A) is a top view of the thin-film resistance element according to the first embodiment, and (b) is a cross-sectional view. (A) thru | or (d) is a figure for demonstrating the formation process of the thin film resistive element which concerns on 1st Embodiment. It is sectional drawing of the thin film resistive element which concerns on 2nd Embodiment. (A) thru | or (d) is a figure for demonstrating the formation process of the thin film resistive element which concerns on 2nd Embodiment. It is a figure which shows the scanning electron micrograph of the cross section of the thin film resistive element which concerns on a 2nd prior art. It is a figure which shows the scanning electron micrograph of the cross section of the thin film resistive element which concerns on 1st Embodiment.

Explanation of symbols

10, 21 Substrate 11, 22 Insulating layer (film)
12a, 12b, 23a, 23b Electrodes 13, 24 Resistance thin film 15, 25 Organic insulating film

Claims (7)

A substrate,
An insulating layer formed on the substrate;
An electrode formed on the substrate or insulating layer;
A passivation layer formed so as to eliminate a step between the electrode and the insulating layer or a discontinuous portion generated in a portion where the electrode and the insulating layer are in contact with each other;
A resistive thin film formed on the passivation layer and the electrode;
A thin film resistance element having   The thin film resistance element according to claim 1, wherein an end portion of the passivation layer is tapered.   The thin film resistance element according to claim 1, wherein the passivation layer is an organic insulating layer. Forming an insulating layer on the substrate;
Forming an electrode on the insulating layer;
A passivation layer forming step of forming a passivation layer so as to eliminate a step between the electrode and the insulating layer;
Forming a resistive thin film on the passivation layer and the electrode;
A method for manufacturing a thin film resistor element. The passivation layer forming step includes
The thin film resistance element manufacturing method according to claim 4, further comprising a step of processing the end portion of the passivation layer so as to be tapered. Forming an insulating layer and an electrode on a substrate;
A passivation layer forming step of forming a passivation layer for filling a step between the electrode and the insulating layer or a discontinuous portion generated at a portion where the electrode and the insulating layer are in contact with each other;
Forming a resistive thin film on the passivation layer and the electrode;
A method for manufacturing a thin film resistor element.   The thin film resistance element manufacturing method according to claim 6, wherein the passivation layer forming step includes a step of forming the passivation layer by spin coating.