JP6883777B2 - Semiconductor devices and methods for manufacturing semiconductor devices - Google Patents

Description

The present invention relates to a semiconductor device and a method for manufacturing the semiconductor device.

As a semiconductor device, a sensor that measures the electrical conductivity of a liquid such as water or a biological liquid mixed with impurities, a semi-solid substance such as clay, soil, or sand, or a powder is known.

For example, in Patent Document 1, a pair of electrodes are brought into contact with each other in soil, the electrical resistance between them is measured to measure the electrical conductivity, and the ion concentration in the soil is specified from the measured electrical conductivity. Thereby, a semiconductor device having a function as a sensor for identifying the water content of soil is described.

International Publication No. 2011/158812

As shown in the ninth step of FIG. 9, the sensor electrode 132 of the semiconductor device 120 described in Patent Document 1 has a semiconductor substrate 122, an insulating layer 124, a first conductive layer 126, a bonding layer 127, and a second conductive film which is a platinum film. A layer 128 and an upper protective film 130 are provided.

As a result of examining the feasibility of the semiconductor device 120 described in Patent Document 1, the manufacturing method of the semiconductor device 120 is first described on a silicon semiconductor substrate 122 as shown in the first step of FIG. By performing the heat treatment in an oxygen atmosphere, an insulating layer 124 such as silicon oxide having a desired thickness is formed. Then, the first conductive layer 126 of aluminum is formed on the insulating layer 124 by sputtering.

Next, as shown in the second step of FIG. 9, a resist mask (not shown) is formed on the first conductive layer 126 in the region corresponding to the sensor electrode 132 by using a lithography technique, and the resist mask is used as a mask. After etching, the resist mask is removed to form the first conductive layer 126 which is the lowermost layer of the sensor electrode 132.

Next, as shown in the third step of FIG. 9, a resist mask film (not shown) covering the insulating layer 124 and the first conductive layer 126 is formed, and the opening 151 is subjected to an exposure step and a developing step. The resist mask 150 provided with the above is formed. At this time, an opening 151 is formed in the outermost peripheral portion of the first conductive layer 126 with the overlapping margin L101 secured. It is necessary to secure the dimensions of the overlapping margin L101 according to the alignment accuracy of the lower layer (first conductive layer 126) and the upper layer (resist mask 150) of the exposure machine.

Next, as shown in the fourth step of FIG. 9, the surface of the resist mask 150 and the surface of the first conductive layer 126 exposed from the opening 151 are a Ti film, a bonding layer 127, and a platinum film, a second. The conductive layer 128 is sequentially formed by sputtering. As a specific example, the thickness of the bonding layer 127 is 0.02 μm, and the thickness of the second conductive layer 128 is 0.1 μm.

Further, prior to forming the bonding layer 127 by sputtering, in order to remove the natural oxide film formed on the surface of the first conductive layer 126 exposed from the opening 151 of the resist mask 150, the first conductive layer 126 is formed. Reverse sputtering is performed to sputter argon (Ar) ions on the surface. The reverse sputtering is also performed in the same apparatus as the sputtering treatment of the bonding layer 127 and the second conductive layer 128. When the first conductive layer 126 is left in the air, its surface is oxidized by the moisture in the air. However, by performing the reverse sputtering, the first conductive layer 126 and the bonding layer 127 are formed by the natural oxide film formed. It is suppressed from obstructing the electrical connection of the.

Next, as shown in the fifth step of FIG. 9, patterning of the bonding layer 127 and the second conductive layer 128 is performed. By removing the resist mask 150 in the chemical solution, the laminated film of the bonding layer 127 and the second conductive layer 128 formed on the resist mask 150 is removed by the lift-off method. As a result, a laminated film of the bonding layer 127 and the second conductive layer 128 is formed in a desired region on the surface of the first conductive layer 126.

Next, as shown in the sixth step of FIG. 9, the surface of the insulating layer 124, the surface of the first conductive layer 126 coated with the resist mask as the overlapping margin L101, and the surface of the second conductive layer 128 are covered. The upper protective film 130 is formed.

Next, as shown in the seventh step of FIG. 9, the resist mask 152 having the opening 153 in the region of the upper protective film 130 corresponding to the region where the electrodes of the second conductive layer 128 need to be exposed is protected in the upper layer. It is formed on the film 130. At this time, the opening 153 is formed in a state where the overlapping margin L102 is secured on the outermost peripheral portion of the second conductive layer 128. The overlapping margin L102 secures dimensions corresponding to both the alignment accuracy of the exposure machine with respect to the second conductive layer 128 as the lower layer and the resist mask 153 as the upper layer and the processing accuracy of the second conductive layer 128 as the lower layer. There is a need to.

Next, as shown in the eighth step of FIG. 9, the desired region of the sensor electrode 132 of the second conductive layer 128 is exposed by performing etching using the resist mask 152 formed on the upper protective film 130 as a mask. Let me.

Next, as shown in the ninth step of FIG. 9, the sensor electrode 132 of the semiconductor device 120 is manufactured through the step of removing the resist mask 152.

As a result of the examination by the inventors, it has been found that the semiconductor device 120 described in Patent Document 1 manufactured in this way has the following problems when the product is supplied by mass production.

As the first problem, in the semiconductor device 120 described in Patent Document 1, the size of the second conductive layer 128 exposed from the upper protective film 130 is smaller than the size (area) of the entire second conductive layer 128. It was found that the size of the region functioning as the sensor electrode 132 was reduced.

In general, in a wafer process in which patterns formed by using a large number of masks are laminated, it is necessary to consider the superposition of the pattern formed in the lower layer and the pattern formed in the upper layer in the exposure step of the lithography process. ..

In the manufacturing method of the semiconductor device 120 described in Patent Document 1 (see FIG. 9), it is necessary to consider the superposition of patterns in the third step and the seventh step.

As described above, in the third step, as shown in FIG. 10, it is necessary to form a resist mask pattern in consideration of the superposition margin L101 as the superposition margin according to the superposition accuracy of the exposure machine.

On the other hand, in the seventh step, as shown in FIG. 10, the superposition margin according to the superposition accuracy of the exposure machine and the superposition according to the variation 160 of the end portion of the laminated film of the bonding layer 127 and the second conductive layer 128. It is necessary to form the resist mask 152 in consideration of the sum of squares with the margin as the superposition margin L102.

Here, the sensor electrode 132 of the semiconductor device 120 is arranged in an environment for measuring the ion concentration and the amount of water contained in the water content of the soil. Therefore, when the surface of the first conductive layer 126 is exposed in the opening 135 of the upper protective film 130, the first conductive layer 126 made of aluminum is easily corroded, and the function of the sensor is impaired. Therefore, it is required that the upper protective film 130 and the first conductive layer 126 completely overlap.

For the above reason, in the seventh step, the opening 153 of the resist mask 152 is formed so that the end face (end portion) of the laminated film of the bonding layer 127 and the second conductive layer 128 is completely covered by the upper protective film 130. It is necessary to do. In particular, since the bonding layer 127 and the second conductive layer 128 are formed by the lift-off method as in the fifth step described above, the end 160 of the laminated film of the bonding layer 127 and the second conductive layer 128 is an opening of the resist mask 150. There will be variations that are extremely difficult to control depending on the part. Therefore, it is necessary to secure an extremely large dimension of the overlap margin L102 as compared with the overlap margin used in a normal wafer process (for example, the overlap margin L101).

Therefore, as shown in FIG. 10, the semiconductor device 120 requires an overlap margin L103 from the end of the first conductive layer 126 to the opening 135, which is the sum of the overlap margin L101 and the overlap margin L102. It becomes. When the size of the first conductive layer 126 is specified, the area where the second conductive layer 128 is exposed from the opening 135 of the upper protective film 130 is the overlapping margin L101 from the end of the first conductive layer 126. And the sum of squares of the overlapping margin L102 are reduced in size corresponding to the combined area. As described above, the area where the second conductive layer 128 that functions as the sensor electrode 132 is exposed from the opening 135 of the upper protective film 130 is reduced, so that the sensitivity of the sensor is lowered.

As a second issue, as a result of the examination by the inventors, in the semiconductor device 120 described in Patent Document 1, the interface between the laminated film of the bonding layer 127 and the second conductive layer 128 and the first conductive layer 126 is formed. It turned out that impurities were present. Further, in the case of mass production as a product due to the presence of impurities, the defective rate increases due to the occurrence of defective products with reduced measurement accuracy, and the bonding layer 127 and the second conductive layer are used for a long period of time. It has been found that the reliability is insufficient due to the problem of peeling at the interface between the 128 laminated film and the first conductive layer 126.

Since platinum is a substance that is extremely difficult to remove by dry etching, the lift-off method is generally used for patterning. Generally, in the lift-off method, an opening of a resist mask that exposes the base film is provided, a thin film is formed on the surface of the resist mask and the surface of the base film exposed from the opening, and then the surface of the resist mask is formed together with the resist mask. By removing the thin film formed in, a thin film pattern having a desired shape is formed on the surface of the undercoat film.

In the semiconductor device 120 described in Patent Document 1, as described above in the fourth step, a laminated film of the bonding layer 127 and the second conductive layer 128 is provided on the surfaces of the first conductive layer 126 and the resist mask 150 exposed from the resist mask 150. Is formed by sputtering, and then the resist mask 150 is removed in the fifth step to pattern the laminated film of the bonding layer 127 and the second conductive layer 128 on the first conductive layer 126.

At this time, as described above, reverse sputtering is performed in order to remove the natural oxide film formed on the surface of the first conductive layer 126. As shown in FIG. 11A, when the natural oxide film formed on the surface of the first conductive layer 126 is removed by sputtering with ions (sputtering component 170), the carbon component 171 is knocked out from the surface of the resist mask 150. Therefore, the carbon component 172 reattaches to the surface of the first conductive layer 126.

Subsequently, as shown in FIG. 11B, the bonding layer 127 is formed with the carbon component 172 adhering to the surface of the first conductive layer 126. Since the bond layer 127 is formed, the carbon component 172 is present at the interface between the first conductive layer 126 and the bond layer 127.

Further, as shown in FIG. 11C, a second conductive layer 128, which is a platinum film, is formed on the bonding layer 127. Therefore, even after the second conductive layer 128 is formed, the carbon component 172 remains at the interface between the first conductive layer 126 and the bonding layer 127.

Therefore, as shown in FIG. 11D, in the semiconductor device 120 described in Patent Document 1, the carbon component 172 is present between the first conductive layer 126 and the bonding layer 127.

That is, when manufacturing the semiconductor device 120 described in Patent Document 1, carbon is formed when reverse sputtering is performed, and a natural oxide film is formed between the first conductive layer 126 and the bonding layer 127 when reverse sputtering is not performed. It will be present as an impurity at the interface of.

If impurities are present at the interface between the first conductive layer 126 and the bond layer 127, the electrical connection between the first conductive layer 126 and the bond layer 127 is hindered, and the first conductive layer 126 and the bond layer 127 are combined. Adhesion is reduced. Inhibition of electrical connection causes a decrease in yield in the manufacture of the semiconductor device 120, that is, an increase in the defect rate due to the manufacture of the semiconductor device 120 in which the desired performance as a sensor cannot be obtained. Further, due to the decrease in adhesion, when the semiconductor device 120 is used for a long period of time, the first conductive layer 126 and the bonding layer 127 are peeled off, and as a result, the first conductive layer 126 and the second conductive layer 128 are separated from each other. Electrical connection failure occurs, leading to lack of reliability.

As described above, the semiconductor device described in Patent Document 1 has the first problem that the sensitivity of the sensor is lowered because the area of the electrode in contact with the soil is reduced. Further, in the semiconductor device described in Patent Document 1, a platinum layer laminated on a first layer made of aluminum via a bonding layer made of titanium is used as an electrode. There is a second problem that the reliability may be lowered because the electrical connection may be poor.

An object of the present invention is to provide a semiconductor device capable of suppressing a decrease in sensitivity of a sensor and improving reliability.

In order to achieve the above object, the semiconductor device of the present invention is formed on a semiconductor substrate and a main surface of the semiconductor substrate, and has a first conductive layer for a first sensor electrode and a first conductive layer for the first sensor electrode. A first sensor electrode that is formed on the layer and has a second conductive layer for the first sensor electrode that is flush with the end face of the first conductive layer for the first sensor electrode and outputs an input signal. , Formed on the main surface of the semiconductor substrate, formed on the first conductive layer for the second sensor electrode and the first conductive layer for the second sensor electrode, and the end surface is the first for the second sensor electrode. A second sensor electrode provided with a second conductive layer for a second sensor electrode that is flush with the end face of the conductive layer, and an input signal output from the first sensor electrode is input as an output signal, and the first sensor. The side surface of the first conductive layer for the electrode, the side surface and the outer periphery of the surface of the second conductive layer for the first sensor electrode, the side surface of the first conductive layer for the second sensor electrode, and the second conductive layer for the second sensor electrode. An upper protective film that covers the side surface and the outer periphery of the surface of the surface and exposes the surface of a region of the second conductive layer for the first sensor electrode that corresponds to the first sensor electrode, and the first sensor electrode. It is electrically connected to the first sensor electrode and is formed on the first conductive layer for the first electrode and the first conductive layer for the first electrode, and the end face is the first electrode for the first electrode. A first electrode having a second conductive layer for the first electrode that is flush with the end face of the first conductive layer, and a second electrode that corresponds to the second sensor electrode and is electrically connected to the second sensor electrode. The second conductive layer for the second electrode, which is formed on the first conductive layer for the second electrode and the first conductive layer for the second electrode and whose end face is flush with the end face of the first conductive layer for the second electrode. The upper protective film is further provided with an opening that exposes the upper surfaces of the first electrode and the second electrode, respectively, and is provided on the upper surface of the first electrode corresponding to the opening. Is not provided with the second conductive layer for the first electrode, the first conductive layer for the first electrode is exposed, and the upper surface of the second electrode corresponding to the opening is for the second electrode. The second conductive layer is not provided, and the first conductive layer for the second electrode is exposed .

Further, in order to achieve the above object, in the method for manufacturing a semiconductor device of the present invention, a semiconductor substrate having a sensor electrode forming region and a mounting electrode forming region adjacent to the sensor electrode forming region is prepared on the main surface. The step, a laminated film forming step of forming a laminated film in which the first conductive layer and the second conductive layer are continuously laminated in order on the main surface of the semiconductor substrate, and the patterning of the laminated film by dry etching. The electrode forming step of forming the sensor electrode in the sensor electrode forming region and forming the mounting electrode in the mounting electrode forming region, the main surface, and the outer periphery of the surface of the sensor electrode and the mounting electrode. An upper layer protective film forming step of forming an upper layer protective film having an opening for exposing the second conductive layer of the sensor electrode and an opening for exposing the second conductive layer of the mounting electrode while covering the sensor electrode, and the sensor. A mask layer forming step of covering an opening that exposes the second conductive layer of the electrode and forming a mask layer that exposes a region including an opening that exposes the second conductive layer of the mounting electrode, and the mask. A second conductive layer removing step of removing the second conductive layer of the mounting electrode by etching a region corresponding to the layer is included.

According to the present invention, it is possible to suppress a decrease in the sensitivity of the sensor and improve the reliability.

It is a schematic block diagram (plan view) of the semiconductor device which mounts the semiconductor device which has a sensor function of this embodiment. FIG. 5 is a cross-sectional view taken along the line AA of the semiconductor device shown in FIG. It is a figure explaining the manufacturing method of the semiconductor device of this embodiment. It is the schematic which shows the structure of the semiconductor device and the control part at the time of measuring an object to be measured. It is explanatory drawing explaining that the semiconductor device of this embodiment solves the 1st problem which the semiconductor device described in Patent Document 1 has. It is explanatory drawing explaining that the semiconductor device of this embodiment solves the second problem which the semiconductor device described in Patent Document 1 has. It is a graph which shows the frequency characteristic of the electric conductivity of the soil measured by the semiconductor device of this embodiment. It is a graph which shows the frequency characteristic of the electric conductivity of the soil measured by the semiconductor device of the comparative example. It is a schematic block diagram (cross-sectional view) which shows the other structural example of the semiconductor device which has a sensor function of this embodiment. It is a figure explaining the manufacturing method of the semiconductor device described in Patent Document 1. It is explanatory drawing for demonstrating the first problem which the semiconductor device described in Patent Document 1 has. It is explanatory drawing for demonstrating the second problem which the semiconductor device described in Patent Document 1 has.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, the "thickness" means the thickness of the semiconductor device 20 in the stacking direction. Further, the "size" refers to the size of the area of the surface of the substrate (the surface intersecting the stacking direction).

First, the configuration of the semiconductor device of this embodiment will be described. The semiconductor device 20 of this embodiment has a function of an EC (Electric Conductivity) sensor. FIG. 1 shows a schematic configuration diagram (plan view) of the semiconductor device 10 in which the semiconductor device 20 of the present embodiment is mounted on the printed circuit board 12 as viewed from the main surface side of the printed circuit board 12. Further, FIG. 2 shows a sectional view taken along line AA of the semiconductor device 10 shown in FIG.

As shown in FIG. 1, the semiconductor device 20 of the present embodiment has a pair of sensor electrodes 32_1 and 32_2 formed in a sensor electrode forming region 40, and a pair of sensor electrodes 32_1 and 32_2 formed in a mounting pad (mounting electrode) forming region 41. It is provided with mounting pads 34_1 and 34_2. The sensor electrode 32_1 and the mounting pad 34_1 are electrically connected by wiring 29_1. Further, the sensor electrode 32_2 and the mounting pad 34_2 are electrically connected by wiring 29_2. The mounting pad 34_1 of the present embodiment is an example of the first electrode of the present invention, and the mounting pad 34_1 is an example of the second electrode of the present invention.

Since the sensor electrode 32_1 and the sensor electrode 32_2 have the same configuration, and the mounting pad 34_1 and the mounting pad 34_2 have the same configuration, they are not distinguished in FIG. 2 and the following description. When generically referred to, the description of the codes "_1" and "_2" for distinguishing the individual is omitted. Further, in FIG. 1, "_1" assigned to the reference numerals representing the configurations related to the sensor electrode 32_1 and the mounting pad 34_1 and the reference numerals representing the configurations related to the sensor electrode 32_1 and the mounting pad 34_1 are added to the reference numerals. If "_2" is also collectively referred to without distinguishing between them, the description thereof will be omitted.

Although the semiconductor device 20 of the present embodiment includes one pair of sensor electrodes 32, a plurality of pairs of sensor electrodes may be provided.

As shown in FIG. 2, in the semiconductor device 20, the insulating layer 24 is laminated on the main surface of the semiconductor substrate 22. As an example, a silicon (Si) substrate (wafer) is used for the semiconductor substrate 22. Examples of the insulating layer 24 include a general insulating layer, and specific examples thereof include an oxide film made of _{silicon oxide (SiO 2).}

On the insulating layer 24, a sensor electrode 32, a mounting pad 34, and an upper layer protective film 30 on which an opening 35 and an opening 36 are formed are laminated. As shown in FIGS. 1 and 2, the sensor electrode 32 includes a first conductive layer 26A and a second conductive layer 28A that are sequentially laminated on the insulating layer 24. The size of the sensor electrode 32 may be a size that can detect an electric signal, and may be determined according to the sensitivity of the sensor and the environment of the measurement target such as soil. As a specific example, 1 mm ² Can be mentioned.

Further, the mounting pad 34 includes the first conductive layer 26B and the second conductive layer 28B which are sequentially laminated on the insulating layer 24 like the sensor electrode 32, but as shown in FIGS. 1 and 2, the mounting pad 34 includes the first conductive layer 26B and the second conductive layer 28B. The opening 36 is not provided with the second conductive layer 28B.

The materials of the first conductive layers 26A and 26B can be appropriately selected depending on the application, purpose and the like, and specific examples thereof include aluminum (Al). Specific examples of the thickness of the first conductive layers 26A and 26B include 1 μm.

Ti-containing films are used as the second conductive layers 28A and 28B, and specific examples of the materials include titanium nitride (TiN). Specific examples of the thickness of the second conductive layers 28A and 28B include 0.1 μm.

The upper protective film 30 has a function of protecting the side surfaces of the first conductive layers 26A and 26B, which are easily corroded by external factors, and is provided in the opening 35 corresponding to the sensor electrode 32 and the mounting pad 34. A corresponding opening 36 is provided. As the upper protective film 30, a single-layer nitride film or a laminated film of an oxide film and a nitride film is used. Specific examples of the thickness of the upper protective film 30 include 0.8 μm.

A pad 14 is arranged on the printed circuit board 12, and the first conductive layer 26B of the mounting pad 34 and the pad 14 are connected by a wire 19 and a ball 16 of the wire 19. Further, the mounting pad 34 (mounting pad forming region 41), the ball 16, the wire 19, and the pad 14 are sealed with the sealing resin 18.

Next, an example of the manufacturing method of the semiconductor device 20 of the present embodiment will be described with reference to FIG.

In the method for manufacturing the semiconductor device 20 of the present embodiment, first, the first step of forming the second conductive layer 28 for the sensor electrode 32 is carried out. As shown in the first step of FIG. 3, first, a semiconductor device 22 having a sensor electrode forming region 40 and a mounting pad forming region 41 is prepared on the main surface. Then, the insulating layer 24 is formed on the main surface of the semiconductor substrate 22. Specific examples of the method for forming the insulating layer 24 include a thermal oxidation method and a CVD (Chemical Vapor Deposition) method. Further, in the first step, the first conductive layer 26 and the second conductive layer 28 are sequentially formed on the insulating layer 24. Specific examples of the method for forming the first conductive layer 26 and the second conductive layer 28 include sputtering. In the present embodiment, the first conductive layer 26 and the second conductive layer 28 are sequentially formed by sputtering in the same apparatus. By forming the first conductive layer 26 and the second conductive layer 28 in the same apparatus in this way, the adhesion between the first conductive layer 26 and the second conductive layer 28 is ensured. Specific examples of the method for forming the second conductive layer 28 include a method for forming a conductive film of TiN by sputtering a Ti target with _{N 2 gas.}

Next, the second step of forming the resist masks 50A and 50B is carried out. As shown in the second step of FIG. 3, a resist mask 50A covering a region corresponding to the pattern of the sensor electrode 32 is formed in the sensor electrode forming region 40 on the second conductive layer 28, and at the same time, a mounting pad is formed. A resist mask 50B that covers a region corresponding to the pattern of the mounting pad 34 is formed in the formation region 41. Further, although the description is omitted, in the second step, at the same time as the resist masks 50A and 50B, a resist mask covering the region forming the wiring 29 (see FIG. 1) is also formed.

As a method for forming the resist masks 50A and 50B, a known lithography technique can be applied. As a lithography technique, a resist mask coating step of applying a resist mask on the second conductive layer 28, an exposure step of exposing a desired pattern to the resist mask, and a developing step of forming a resist mask according to the exposed pattern. including.

Next, a third step of etching the first conductive layer 26 and the second conductive layer 28 is carried out. As shown in the third step of FIG. 3, the second conductive layer 28 and the first conductive layer 26 were etched by a dry etching method or the like using the resist masks 50A and 50B as masks, so that the pattern of the sensor electrode 32 was adjusted. The first conductive layer 26A and the second conductive layer 28A, the first conductive layer 26B and the second conductive layer 28B corresponding to the pattern of the mounting pad 34, and the wiring 29 (see FIG. 1) are formed. The second conductive layer 28A formed in the third step functions as an electrode layer of the sensor electrode 32. Further, the first conductive layer 26B formed in the third step functions as a mounting electrode.

In the third step, when etching is performed, the end face of the first conductive layer 26A and the end face of the second conductive layer 28A are flush with each other, and the end face of the first conductive layer 26B and the end face of the second conductive layer 28B are flush with each other. I try to be flush. In the present embodiment, the "end surface" refers to a surface in the stacking direction, for example, a side surface around the main surface. Further, in the present embodiment, "facial" means that it can be regarded as flush, including an error.

Next, a fourth step of removing the resist masks 50A and 50B is carried out. As shown in the fourth step of FIG. 3, the resist masks 50A and 50B are removed by, for example, ashing with oxygen plasma or the like and then removing the residue by chemical washing or the like.

Next, the fifth step of forming the upper protective film 30 is carried out. As shown in the fifth step of FIG. 3, the upper protective film 30 that covers the surface of the insulating layer 24, the sensor electrode 32, and the mounting pad 34 is formed by a plasma CVD method or the like.

Next, the sixth step of forming the resist mask 52 is carried out. As shown in the sixth step of FIG. 3, the opening 53A corresponding to the region where the second conductive layer 28A of the sensor electrode 32 is exposed and the opening corresponding to the region where the first conductive layer 26B of the mounting pad 34 is exposed. A resist mask 52 having a portion 53B is formed on the upper protective film 30. The method for forming the resist mask 52 is not particularly limited, but for example, a known lithography technique can be applied as in the resist masks 50A and 50B in the second step described above.

Here, in the exposure step of the sixth step, the lower layer sensor electrode 32 and the mounting pad 34 and the upper layer resist mask openings 53A and 53B are overlapped with each other to obtain a desired position of the sensor electrode 32 and the mounting pad 34. The opening 35 and the opening 36 of the upper protective film 30 are formed in the upper layer protective film 30. Excessive displacement between the upper resist masks 53A and 53B and the lower sensor electrodes 32 and mounting pads 34 causes displacement between the sensor electrodes 32 and the mounting pads 34 and the openings 35 and 36 of the upper protective film 30. In order not to cause a problem that the semiconductor device 20 does not satisfy the desired function, a superposition margin for superimposing the upper layer resist masks 53A and 53B on the lower layer sensor electrode 32 and the mounting pad 34 is required. .. The superposition margin requires dimensions according to the processing variation of the sensor electrode 32 and the mounting pad 34, in addition to the superposition accuracy of the exposure machine itself.

Here, when the first conductive layer 26A is exposed in the opening 35 of the upper layer protective film 30 formed in the next seventh step, the first conductive layer 26A is corroded by the usage environment when the semiconductor device 20 is used as a sensor. The opening 53A of the sensor electrode forming region 40 needs to consider a superposition margin in consideration of the superposition accuracy of the exposure machine used in the exposure step. In other words, the size of the sensor electrode 32 needs to be a region obtained by adding the overlapping margin to the required opening 35 (exposed size of the second conductive layer 28A).

Next, a seventh step of etching the upper protective film 30 is carried out. As shown in the seventh step of FIG. 3, the upper protective film 30 is etched using the resist mask 52 as a mask to form the openings 35 and 36. At this time, the selection ratio between the etching rate of the upper protective film 30 and the etching rates of the second conductive layers 28A and 28B is high, and the second conductive layer 28A on the bottom surface of the opening 35 and the bottom surface of the opening 36 have a high selection ratio. Etching is performed in an etching process in which the second conductive layer 28B is not removed.

Next, the eighth step of removing the resist mask 52 is carried out. As shown in the eighth step of FIG. 3, for example, as described above in the fourth step, the resist mask 52 is removed by ashing with oxygen plasma or the like and then removing the residue by washing with a chemical solution or the like.

Next, the ninth step of forming the resist mask 56 is carried out. As shown in the ninth step of FIG. 3, a resist mask 56 having an opening 57 corresponding to a region including an opening 36 that exposes the first conductive layer 26B of the mounting pad forming region 41 is formed. In the ninth step, the second conductive layer 28A exposed from the opening 35 of the upper protective film 30 on the sensor electrode 32 is in a state of being covered with the resist mask 56.

Next, the tenth step of removing the second conductive layer 28B exposed from the opening 36 of the upper layer protective film 30 is carried out. As shown in the tenth step of FIG. 3, etching is performed by self-alignment using the resist mask 56 and the upper protective film 30 as masks. In the tenth step, the second conductive layer 28A of the sensor electrode 32 is not etched because it is covered with the resist mask 56. By performing etching by self-alignment using the resist mask 56 and the upper layer protective film 30 as masks in this way, the second conductive layer 28B can be provided and the size of the opening 36 can be minimized. Therefore, in the semiconductor device 20, the chip size can be reduced and the manufacturing cost can be reduced.

Further, since the surface of the upper protective film 30 exposed from the resist mask 56 is etched at the same time as the second conductive layer 28B, it corresponds to the boundary of the region including the opening 36, that is, the edge of the opening 57 of the resist mask 56. A step 31 is formed around the formed opening 36.

Next, the eleventh step of removing the resist mask 56 is carried out. As shown in the eleventh step of FIG. 3, for example, in the same manner as described above in the fourth step, the resist mask 56 is removed by ashing with oxygen plasma or the like and then removing the residue by washing with a chemical solution or the like.

In the present embodiment, the semiconductor device 20 shown in FIGS. 1 and 2 is manufactured by the first to eleventh steps shown in FIG.

The method of specifying the water content in the soil, which is an example of the dispersion system, using the semiconductor device 20 of the present embodiment as an EC sensor is not particularly limited. As an example, a method of specifying the water content by detecting the phase change θ of the electric signal will be described.

The output of the semiconductor device 20 is proportional to the water content and the ion concentration, and if the ion concentration is specified, the water content in the soil can be specified by EC (electrical conductivity).

When performing measurement, as shown in FIG. 4, the mounting pad 34 of the semiconductor device 20 is connected to the control unit 1 via the pad 14.

First, the sensor electrode 32 (more specifically, the second conductive layer 28A) of the semiconductor device 20 is brought into contact with the soil to be measured. When performing measurement, an AC electric signal having a predetermined frequency is applied as an input signal from the control unit 1 to one of the sensor electrodes 32_1. The sensor electrode 32_1 outputs the input signal. In the sensor electrode 32_2, the input signal output from the sensor electrode 32_1 is input as an output signal via the measurement target. The control unit 1 compares the phase with the phase of the electric signal output from the other sensor electrode 32_2. A specific example of the comparison result is to detect the phase difference (phase change θ) between the two. When the phase change θ is detected, the ion concentration is specified by the detected phase change θ. The phase change θ and the ion concentration are associated with each other in advance. Furthermore, the water content of the soil can be specified by the measured EC based on the specified ion concentration. In the semiconductor device 20 of the present embodiment, since the phase change θ can be detected by using the sensor electrode 32 in the time division method, the electrode for detecting the phase change θ (for example, the prior art (International Publication No. 2011)). EC can be measured without providing the electrode for movement measurement in the semiconductor device of / 158812)).

Other methods include the TDR (Time Domain Reflectometry) method (see, for example, Japanese Patent Application Laid-Open No. 10-62368) in which the amount of water between two points is determined from the propagation velocity of electromagnetic waves between the two points, and the capacitance of soil. (For example, see Japanese Patent Application Laid-Open No. 2001-21517) and the like.

As described above, the semiconductor device 20 of the present embodiment is formed on the semiconductor substrate 22 and the main surface of the semiconductor substrate 22, is formed on the first conductive layer 26A and the first conductive layer 26A, and has an end surface. Is provided with a second conductive layer 28A that is flush with the end surface of the first conductive layer 26A, and is formed on the main surface of the semiconductor substrate 22 and the sensor electrode 32_1 that outputs an input signal. The second conductive layer 28B, which is formed on the first conductive layer 26B and whose end face is flush with the end face of the first conductive layer 26B, is provided, and the input signal output from the sensor electrode 32_1 is input as an output signal. Covers the sensor electrode 32_2, the side surface of the first conductive layer 26A, the outer periphery of the side surface and the surface of the second conductive layer 28A, and the outer periphery of the side surface of the first conductive layer 26B and the side surface and the surface of the second conductive layer 28B. In addition, an upper protective film 30 that exposes the surface of a predetermined region corresponding to the opening 35 (sensor electrode 32) of the first conductive layer 26A is provided.

The operation of the semiconductor device 20 of the present embodiment on the first problem that occurs in the semiconductor device 120 described in Patent Document 1 will be described with reference to FIG.

In the semiconductor device 20 of the present embodiment, a TiN film which is a Ti-containing film is used for the second conductive layer 28A of the sensor electrode 32, and the first conductive layer 26A and the second conductive layer 28A are combined in the third step. As described, the same resist masks 50A and 50B are used for processing.

Therefore, since the end portion of the first conductive layer 26A and the end portion of the second conductive layer 28A processed by dry etching are formed on the same processed surface, the semiconductor device 120 described in Patent Document 1 is manufactured. The superposition margin L101 (see FIGS. 9 and 10) required at this time becomes unnecessary (superimposition margin L1 = 0) as shown in FIG.

Further, in general, since the end portion of the pattern processed by dry etching depends on the resist mask, the pattern is processed by the lift-off method used in manufacturing the semiconductor device 120 described in Patent Document 1. The variation 160 (see FIG. 10) that occurs at the end portion of the pattern does not occur, and the forming accuracy of the pattern end portion 60 is high. Therefore, when manufacturing the semiconductor device 20 of the present embodiment, as described above, the bonding layer 127 and the second conductive layer 128 generated by using the lift-off method when manufacturing the semiconductor device 120 described in Patent Document 1. It is not necessary to consider the variation of the end portion 160 of the laminated film, and as shown in FIG. 5, the overlay margin L2 according to the overlay accuracy of the exposure machine, that is, the minimum overlay margin can be set. Therefore, the overlap margin L2 in the sixth step of the manufacturing process of the semiconductor device 20 of the present embodiment is extremely larger than the overlap margin L102 required when manufacturing the semiconductor device 120 described in Patent Document 1. It becomes smaller.

That is, in the semiconductor device 120 described in Patent Document 1, the superposition margin L101 and the superposition margin L102 were required, but as shown in FIG. 5, the superposition margin required in the semiconductor device 20 of the present embodiment is required. L3 is equal to the overlap margin L1 and smaller than the overlap margin L102.

Therefore, the sensor electrode 32 of the semiconductor device 20 of the present embodiment completely covers the end portion (side surface) of the sensor electrode 32 with the upper layer protective film 30, and only the overlap margin L2 in the sixth step needs to be considered. The second conductive layer 28A, which has the maximum size with respect to the area of the first conductive layer 26A, can be exposed from the upper protective film 30.

Therefore, in the semiconductor device 20 of the present embodiment, the sensitivity of the sensor can be increased as compared with the semiconductor device 120 described in Patent Document 1, and even when the cost is reduced by reducing the chip size or the like. It becomes possible to maintain the sensitivity of the sensor.

Next, the operation of the semiconductor device 20 of the present embodiment on the second problem that occurs in the semiconductor device 120 described in Patent Document 1 will be described with reference to FIG.

In the semiconductor device 20 of the present embodiment, since the TiN film which is a Ti-containing film is used for the second conductive layer 28A of the sensor electrode 32, the first conductive layer 26A and the second conductive layer 28A are shown in FIG. Are continuously formed in the same apparatus in the above-mentioned first step, and the first conductive layer 26A and the second conductive layer 28A are simultaneously patterned in the above-mentioned third step. Therefore, there is no factor that hinders the adhesion between the first conductive layer 26A and the second conductive layer 28A.

Further, as shown in FIG. 6, when the resist mass 50A is removed in the above-mentioned fourth step, the surface of the second conductive layer 28A becomes clean.

After that, as shown in FIG. 6, the upper layer protective film 30 is formed by the above-mentioned fifth step, and further, in the eighth step, the resist mask 52 formed on the upper layer protective film 30 is removed, and the eleventh step is performed. In the process, the resist mask 56 is removed. When the resist mask 52 is removed and when the resist mask 56 is removed, the surface of the second conductive layer 28A becomes clean.

That is, in the method for manufacturing the semiconductor device 20 of the present embodiment, it is not necessary to use the lift-off method for processing the first conductive layer 26A and the second conductive layer 28A, and the method for manufacturing the semiconductor device 120 described in Patent Document 1 As described above, there is no step of reverse sputtering the surface of the resist mask with the first conductive layer 26 exposed.

Therefore, in the semiconductor device 20 of the present embodiment, since impurities existing at the interface between the first conductive layer 26A and the second conductive layer 28A are suppressed, it is possible to bring the interface closer to an ideal state in which impurities do not exist. It becomes.

In order to suppress the presence of impurities, in the semiconductor device 20 of the present embodiment, the electrical connection between the first conductive layer 26A and the second conductive layer 28A can be made stable, and the yield in manufacturing is improved. It becomes possible to make it. Further, in the semiconductor device 20 of the present embodiment, it is possible to improve the adhesion between the first conductive layer 26A and the second conductive layer 28A, and the first conductive layer 26A and the second conductive layer 28A can be used for a long period of time. It is possible to improve the reliability because the electrical connection failure with the device does not occur.

FIG. 7A shows a graph showing the impedance Z and the phase difference Θ with respect to the measurement frequency as the frequency characteristics of the electrical conductivity of the soil measured by the semiconductor device 20 of the present embodiment. Further, FIG. 7B shows a graph showing the impedance Z and the phase difference Θ with respect to the measurement frequency as the frequency characteristics of the electrical conductivity of the soil measured by the semiconductor device 120 described in Patent Document 1. As shown in FIGS. 7A and 6B, the sensor electrode 32 of the semiconductor device 20 of the present embodiment, specifically, the second conductive layer 28A, and the sensor electrode 132 of the semiconductor device 120 described in Patent Document 1, specifically, Even if it is different from the second conductive layer 128, there is no large difference in frequency characteristics (difference to the extent that it causes a problem in measurement).

As described above, in the semiconductor device 20 of the present embodiment, even if the sensor electrode 32 is different from the sensor electrode 132 of the semiconductor device 120 described in Patent Document 1, the frequency characteristic is maintained and the decrease in the sensitivity of the sensor is suppressed. At the same time, reliability can be improved.

Further, in the semiconductor device 20 of the present embodiment, Ti-containing films (TiN) are used as the second conductive layers 28A and 28B, and expensive platinum, which is a rare metal and a precious metal, is not used. Therefore, the manufacturing cost of the semiconductor device 20 is high. Can be suppressed. Further, since TiN generally has higher mechanical strength than platinum, in the semiconductor device 20 of the present embodiment, friction caused by contact with a semi-solid object such as clay, soil, and sand is generated. As a result, surface roughness and scraping of the second conductive layer 28A are suppressed, so that deterioration of electrical conductivity can be suppressed.

Further, in the manufacturing method of the semiconductor device 20 of the present embodiment, since the lift-off method is not used and impurities due to the use of the lift-off method are not generated, in addition to the above-mentioned effects, the sputtering device and the organic solvent are peeled off. The equipment is not contaminated by impurities, and the cost and time for equipment maintenance can be suppressed.

The semiconductor device 20 of the present embodiment includes an arithmetic circuit that processes the electric signal, such as a process of amplifying the electric signal output from the sensor electrode 32 and a process of removing noise contained in the electric signal. You may. When an arithmetic circuit is provided, although not shown, for example, an arithmetic in which a general IC manufacturing process is carried out on a semiconductor substrate 22 and a desired element such as a MOS transistor, a bipolar, a resistance element, and a capacitive element is provided. The circuit may be manufactured and the insulating layer 24 may be formed so as to flatten the arithmetic circuit.

Further, the configurations of the sensor electrode 32 and the mounting pad 34 of the semiconductor device 20 are not limited to those described above. For example, as shown in FIG. 8, the semiconductor device 20 includes a sensor electrode 32 in which a first conductive layer 26A, a third conductive layer 27A, and a second conductive layer 28A are sequentially laminated, and a first conductive layer 26B, a third. A mounting pad 34 in which the conductive layer 27B and the second conductive layer 28B are sequentially laminated may be provided. The third conductive layers 27A and 27B are Ti films, and the thickness is 0.1 μm as a specific example.

When the semiconductor device 20 shown in FIG. 8 is manufactured, in the first step (see FIG. 3) in the method for manufacturing the semiconductor device 20 described above, the first conductive layer 26 and the third conductive layer 27A are sequentially placed on the insulating layer 24. , A third conductive layer (not shown) for forming 27B, and a second conductive layer 28 are formed. Specific examples of the method for forming the third conductive layer include a method for forming a Ti film by sputtering a Ti target with Ar gas. The method for forming the first conductive layer 26 and the second conductive layer 28 may be the same as the method described in the first step in the method for manufacturing the semiconductor device 20 described above. Further, each step in the other manufacturing methods may be the same as the above-described step with reference to FIG.

The third conductive layer 27A is a Ti film, and the Ti film generally has a smaller crystal grain size than the TiN film. Therefore, when the third conductive layer 27A is provided as in the semiconductor device 20 shown in FIG. 8, it is possible to prevent impurities contained in the object to be measured from diffusing into the first conductive layer 26A. Further, in the semiconductor device 20 shown in FIG. 8, for example, titanium oxide (TIO) is formed by binding Ti with oxygen in a liquid, but the TiO film has a function as a diffusion prevention film. The effect of suppressing deterioration of the sensor electrode 32 becomes higher.

The configurations, operations, measurement methods, etc. of the semiconductor device 10 and the semiconductor device 20 described in each of the above embodiments are examples, and can be changed according to the situation within a range not deviating from the gist of the present invention. Needless to say, there is.

10 Semiconductor device 20 Semiconductor device 22 Semiconductor substrate 24 Insulation layer 26, 26A, 26B First conductive layer 28, 28A, 28B Second conductive layer 30 Upper layer protective film 31 Step 32 Sensor electrode 34 Mounting pad 35, 36 Opening

Claims (10)

With a semiconductor substrate
It is formed on the main surface of the semiconductor substrate and is formed on the first conductive layer for the first sensor electrode and the first conductive layer for the first sensor electrode, and the end face is the first conductive layer for the first sensor electrode. A first sensor electrode having a second conductive layer for the first sensor electrode that is flush with the end face of the layer and outputting an input signal,
It is formed on the main surface of the semiconductor substrate and is formed on the first conductive layer for the second sensor electrode and the first conductive layer for the second sensor electrode, and the end face is the first conductive layer for the second sensor electrode. A second sensor electrode provided with a second conductive layer for the second sensor electrode that is flush with the end face of the layer, and an input signal output from the first sensor electrode is input as an output signal.
The side surface of the first conductive layer for the first sensor electrode, the side surface and the outer periphery of the surface of the second conductive layer for the first sensor electrode, the side surface of the first conductive layer for the second sensor electrode, and the second sensor electrode. An upper protective film that covers the side surface and the outer periphery of the surface of the second conductive layer and exposes the surface of a region defined according to the first sensor electrode of the second conductive layer for the first sensor electrode.
Corresponding to the first sensor electrode, it is electrically connected to the first sensor electrode and is formed on the first conductive layer for the first electrode and the first conductive layer for the first electrode, and the end face is said. A first electrode having a second conductive layer for the first electrode that is flush with the end face of the first conductive layer for the first electrode,
Corresponding to the second sensor electrode and electrically connected to the second sensor electrode, it is formed on the first conductive layer for the second electrode and the first conductive layer for the second electrode, and the end face is the first. A second electrode having a second conductive layer for a second electrode that is flush with the end face of the first conductive layer for two electrodes,
With
The upper protective film further includes an opening that exposes the upper surfaces of the first electrode and the second electrode, and the upper surface of the first electrode corresponding to the opening is provided with a second conductive material for the first electrode. The layer is not provided and the first conductive layer for the first electrode is exposed, and the second conductive layer for the second electrode is provided on the upper surface of the second electrode corresponding to the opening. The first conductive layer for the second electrode is exposed.
Semiconductor device. The input signal output from the first sensor electrode is input to the second sensor electrode as an output signal via the soil.
The semiconductor device according to claim 1. The second conductive layer for the first sensor electrode and the second conductive layer for the second sensor electrode are made of a substance containing Ti.
The semiconductor device according to claim 1 or 2. The opening of the upper protective film corresponding to the first electrode and the second electrode has a step on the periphery.
The semiconductor device according to any one of claims 1 to 3. The outer peripheral portion of the upper surface of the first electrode is in contact with the upper protective film via the second conductive layer for the first electrode, and the outer peripheral portion of the upper surface of the second electrode is the second electrode for the second electrode. It is in contact with the upper protective film via a conductive layer.
The semiconductor device according to any one of claims 1 to 4. The first sensor electrode, the second sensor electrode, the first electrode, and the second electrode are formed on the main surface of the semiconductor substrate via an insulating layer.
The semiconductor device according to any one of claims 1 to 5. The first sensor electrode and the second sensor electrode are connected to the control unit, and the first sensor electrode and the second sensor electrode are connected to the control unit.
The control unit outputs the input signal, which is an AC signal, to the first sensor electrode, and the phase difference between the output signal and the input signal input from the second sensor electrode and the amount of change in impedance are determined in the soil. Calculate the amount of water in
The semiconductor device according to claim 2. A step of preparing a semiconductor substrate having a sensor electrode forming region and a mounting electrode forming region adjacent to the sensor electrode forming region on the main surface, and
A laminated film forming step of forming a laminated film in which a first conductive layer and a second conductive layer are continuously laminated in this order on a main surface of a semiconductor substrate.
An electrode forming step of patterning the laminated film by dry etching to form a sensor electrode in the sensor electrode forming region and forming a mounting electrode in the mounting electrode forming region.
The main surface and the outer periphery of the surface of the sensor electrode and the mounting electrode are covered, and the opening for exposing the second conductive layer of the sensor electrode and the second conductive layer of the mounting electrode are exposed. An upper layer protective film forming step of forming an upper layer protective film having an opening to be formed,
A mask layer forming step of covering an opening that exposes the second conductive layer of the sensor electrode and forming a mask layer that exposes a region including an opening that exposes the second conductive layer of the mounting electrode.
A second conductive layer removing step of removing the second conductive layer of the mounting electrode by etching a region corresponding to the mask layer.
A method for manufacturing a semiconductor device including. The method for manufacturing a semiconductor device according to claim 8 , wherein the electrode forming step forms the end face of the first conductive layer and the end face of the second conductive layer of the sensor electrode flush with each other. The semiconductor according to claim 8 or 9 , wherein the second conductive layer removing step forms a step according to a boundary of a region including an opening that exposes the second conductive layer of the mounting electrode. Manufacturing method of the device.

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