JP5347422B2 - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device with stabilized laser trimming and suppressed incidence of laser to a semiconductor substrate. <P>SOLUTION: A semiconductor device has a semiconductor substrate 10, a multilayer structure 30 that is stacked on the semiconductor substrate and has a plurality of layers stacked in the thickness direction of the semiconductor substrate, and a resistor 50 stacked on the multilayer structure. In the semiconductor device, a part of the resistor is fused by laser irradiation, and the resistance value of the resistor is regulated. The multilayer structure has a plurality of reflective layers 31 for reflecting the laser and insulating layers 32 arranged among a plurality of the reflective layers and between the reflective layer and the resistor, respectively. At least one of two interfaces between the reflective layer and the insulating layer at the position that is closest to the resistor is formed obliquely to the thickness direction. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a semiconductor device having a resistor whose resistance value is adjusted by laser irradiation.

  Conventionally, a resistor formed by depositing CrSi or the like on a semiconductor substrate through an insulating layer, and irradiating a laser to a resistor formed by forming the CrSi in a predetermined pattern, thereby fusing a part of the resistor. There is known a laser trimming method for adjusting the value to a desired value.

  By the way, in the laser trimming method described above, the reflected light that is transmitted through the resistor and reflected at the interface between the lower insulating layer and the semiconductor substrate causes interference with the incident light incident on the resistor. There was a problem that the resistor could not be blown.

  Therefore, for example, in Patent Document 1, a metal reflective film (reflective layer) is formed under a resistor via an insulating film (insulating layer), and incident light and reflected light from the reflective layer are mutually connected by the resistor. A semiconductor device in which the thickness of the insulating layer is adjusted so as to strengthen is disclosed.

In Patent Document 2, a semiconductor substrate, an oblique region formed on the surface of the semiconductor substrate and oblique to the thickness direction of the semiconductor substrate, and an insulation formed on the semiconductor substrate including the oblique region A semiconductor device having a film (insulating layer) and a thin film resistor (resistor) formed on the insulating layer and above an oblique region is disclosed.
Japanese Patent Laid-Open No. 10-41461 JP-A-10-22252

  Incidentally, in the case of the semiconductor device disclosed in Patent Document 1, in order to form a region where interference light is strengthened by a resistor, the thickness of the insulating layer must be adjusted to the wavelength of the laser. In addition, when a fine structure is formed in the insulating layer, the optical path length of the reflected light varies depending on the fine structure, so that incident light and reflected light from the reflective layer strengthen each other with deformation of the fine structure. The thickness of the insulating layer must be adjusted each time. As a result, there is a concern that the cost is high.

  On the other hand, in the case of the semiconductor device disclosed in Patent Document 2, incident light that has passed through the resistor and the insulating layer and entered the oblique region is oblique to the thickness direction of the semiconductor substrate in the oblique region. As shown in FIG. 6B of Patent Document 2, the interference light between the incident light incident on the semiconductor device and the reflected light reflected in the oblique region becomes complicated as shown in FIG. Thus, a region where the interference light is surely strengthened is formed. As described above, the semiconductor device disclosed in Patent Document 2 is a semiconductor device that can perform laser trimming stably without adjusting the thickness of the insulating layer.

  However, in the semiconductor device disclosed in Patent Document 2, as described above, the oblique region is formed on the surface of the semiconductor substrate. Therefore, there is a possibility that incident light that has been transmitted through the oblique region and incident on the semiconductor substrate interferes in the semiconductor substrate, and the incident light strengthens each other, thereby causing crystal defects or the like in the semiconductor substrate. For this reason, active elements and passive elements cannot be formed under oblique regions in the semiconductor substrate, which may cause a problem that the size of the semiconductor substrate increases.

  In view of the above problems, an object of the present invention is to provide a semiconductor device in which laser trimming is stabilized and laser incidence on a semiconductor substrate is suppressed.

In order to achieve the above-described object, the invention described in claim 1 includes a semiconductor substrate, a multilayer structure laminated on the semiconductor substrate, and a plurality of layers laminated in the thickness direction of the semiconductor substrate, and the multilayer A semiconductor device in which a part of the resistor is melted by laser irradiation and a resistance value of the resistor is adjusted, and the multilayer structure is a laser And a plurality of reflective layers, and a plurality of insulating layers disposed between the reflective layer and the resistor, respectively, and the reflective layer and the insulating layer at a position closest to the resistor In the cross section connecting the electrodes of the resistor , at least one of the two interfaces is connected to the upper side and the lower side along a direction substantially perpendicular to the thickness direction, and the upper side and the lower side are connected. A plurality of concave shapes having a hypotenuse that is inclined with respect to the vertical direction. Comprising Te irregularities (hereinafter referred to as trapezoidal shape) to said Rukoto such a.

  Thus, according to the present invention, the reflective layer for reflecting the laser is provided in multiple layers. Therefore, the laser irradiated to the resistor is configured to be reflected by the plurality of reflective layers before reaching the semiconductor substrate. As described above, the semiconductor device according to the present invention is a semiconductor device in which the incidence of laser on the semiconductor substrate is suppressed as compared with the semiconductor device having one reflective layer. Accordingly, the occurrence of crystal defects in the semiconductor substrate due to the interference of incident light entering the semiconductor substrate is suppressed, so that active elements and passive elements can be formed under the multilayer structure in the semiconductor substrate. Therefore, an increase in the size of the semiconductor substrate can be suppressed.

According to the present invention, at least one of the two interfaces between the reflective layer and the insulating layer at the position closest to the resistor has a trapezoidal shape . Therefore, the laser can be reflected in a direction oblique to the thickness direction at the oblique side of the trapezoidal shape at the interface. That is, reflected waves having different optical path lengths can be reflected by the resistor. As a result, a region where incident light and reflected light always intensify is formed in the resistor, so that laser trimming can be performed stably regardless of the thickness of each layer in the semiconductor device. As described above, the semiconductor device described above is a semiconductor device in which laser trimming is stabilized and laser incidence on the semiconductor substrate is suppressed.

As a specific configuration of a semiconductor device according to the present invention, as reflection layer includes a first reflective layer which are sequentially laminated from the semiconductor substrate in the direction of the resistor, and a second reflective layer, and the insulating layer has a first insulating layer laminated between the first reflective layer and the second reflective layer, a second insulating layer laminated between the second reflective layer and the resistor body. Then, the laminated surface of the second reflection layer in the first insulating layer in a cross section connecting the resistor electrode is formed in a trapezoidal shape, the second reflective layer, the second reflective layer in the first insulating layer It is laminated according to the shape of the laminated surface, and the laminated surface of the first insulating layer and the second reflective layer and the laminated surface of the second reflective layer and the second insulating layer have a trapezoidal shape as an interface. It is as a constituent.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1 is a cross-sectional view illustrating a schematic configuration of the semiconductor device according to the first embodiment. 2A and 2B are cross-sectional views for explaining the method for manufacturing a semiconductor device according to the first embodiment, wherein FIG. 2A shows a first stacking process and a second stacking process, FIG. 2B shows a forming process, (C) shows a 3rd lamination process, (d) shows a 4th lamination process, (e) has shown the 5th lamination process. In the following, the thickness direction of the semiconductor substrate is simply referred to as the thickness direction.

  As shown in FIG. 1, the semiconductor device 100 includes a semiconductor substrate 10, a multilayer structure 30 stacked on the surface 10a of the semiconductor substrate 10, a resistor 50 stacked on the surface 30a of the multilayer structure 30, and The electrodes 51 and 52 and the protective film 70 that covers and protects the resistor 50 and the electrodes 51 and 52 are provided.

  The semiconductor substrate 10 is a region where an active element and a passive element (hereinafter simply referred to as an element) (not shown) are formed. The semiconductor substrate 10 according to the present embodiment is made of single crystal silicon, and an insulating film (not shown) made of silicon oxide is formed on the surface 10a.

  The multilayer structure 30 includes a plurality of reflective layers 31 and a plurality of insulating layers 32. The multilayer structure 30 according to the present embodiment includes two reflecting layers 33 and 34 as the reflecting layer 31 and two insulating layers 35 and 36 as the insulating layer 32, and the two reflecting layers 33 and 34. Is made of silicon nitride, and the two insulating layers 35 and 36 are made of silicon oxide. As shown in FIG. 1, the multilayer structure 30 includes a first reflective layer 33, a first insulating layer 35, a second reflective layer 34, and a second insulating layer 36 in this order from the semiconductor substrate 10 to the resistor 50. The first interface 40 between the second insulating layer 36 and the second reflective layer 34, the second interface 41 between the second reflective layer 34 and the first insulating layer 35, and the first insulating layer 35 and the first The laser incident on the multilayer structure 30 is reflected at the third interface 42 with the reflective layer 33. As shown in FIG. 1, the first interface 40 and the second interface 41 connect the upper side and the lower side along the direction substantially perpendicular to the thickness direction, the upper side and the lower side, and the thickness direction. Thus, a concave-convex shape having a plurality of concave shapes each having a diagonal side (hereinafter, such concave-convex shape is referred to as a trapezoidal shape for convenience). Thereby, a hypotenuse 34b that is inclined with respect to the thickness direction is formed on a part of the surface 34a (first interface 40) of the second reflective layer 34, and the surface 35a (second interface 41) of the first insulating layer 35 is formed. ) Is formed with a hypotenuse 35b that is inclined with respect to the thickness direction. The laser incident on the multilayer structure 30 is reflected by the oblique sides 34b and 35b in a direction oblique to the thickness direction.

  The resistor 50 electrically connects the electrode 51 and the electrode 52 formed of a conductive material such as aluminum with a desired resistance value. The resistor 50 according to the present embodiment is formed by depositing CrSi on the surface 30a of the multilayer structure 30 by sputtering and forming the deposited CrSi in a predetermined pattern. The resistance value of the resistor 50 is adjusted to a desired value by melting a part thereof by laser irradiation.

  The protective film 70 covers and protects the resistor 50 and the electrodes 51 and 52. The protective film 70 according to this embodiment is formed by stacking silicon oxide and silicon nitride in the thickness direction.

  Next, a method for manufacturing the semiconductor device 100 will be described. First, a semiconductor substrate 10 made of single crystal silicon is prepared. Then, an insulating film (not shown) made of silicon oxide is formed on the surface 10a of the semiconductor substrate 10 by thermal oxidation, and a first reflective layer 33 made of silicon nitride is laminated on the silicon oxide by CVD. The above is the first stacking step. After the first stacking step, the first insulating layer 35 made of silicon oxide is stacked on the surface 33a (third interface 42) of the first reflective layer 33 by the CVD method. The above is the second stacking step. Through the above steps, the first reflective layer 33 and the first insulating layer 35 are stacked on the semiconductor substrate 10 as shown in FIG.

  After the second stacking step, as shown in FIG. 2B, the surface 35a (second interface 41) in the first insulating layer 35 is formed into a trapezoidal shape by anisotropic etching. As a result, a hypotenuse 35b that is slanted in the thickness direction is formed on the surface 35a (second interface 41). The above is the forming process. In addition, the length along the oblique side 35b is formed longer than the wavelength of the laser irradiating the resistor 50 in the adjusting step described later, and thereby the laser is reflected.

  After the formation step, as shown in FIG. 2C, the second reflective layer made of silicon nitride is formed on the surface 35a (second interface 41) by the CVD method so as to match the shape of the surface 35a (second interface 41). 34 are stacked. That is, the second reflective layer 34 is uniformly formed on the surface 35a. As a result, a hypotenuse 34b that is inclined with respect to the thickness direction is formed on the surface 34a (first interface 40). The above is the third stacking step. Note that the length along the hypotenuse 34b is approximately the same as the length along the hypotenuse 35b.

  After completion of the third stacking step, molten silicon oxide is injected into the concave portion of the surface 34a (first interface 40) in the second reflective layer 34, and the concave portion is filled by cooling and solidifying. When the silicon oxide is solidified, its surface is flattened by a CMP method. Then, as shown in FIG. 2D, silicon oxide is laminated on the flattened surface of the silicon oxide by the CVD method, thereby forming the second insulating layer 36. The above is the fourth stacking step.

  After the fourth lamination step, as shown in FIG. 2E, the resistor 50 and the electrodes 51 and 51 are formed on the surface 36a of the second insulating layer 36 (the surface 30a of the multilayer structure 30) by sputtering. . Then, a protective film 70 in which silicon oxide and silicon nitride are laminated in the thickness direction is formed on the surface 36a (30a) so as to cover the resistor 50 and the electrodes 51 and 52 by the CVD method. The above is the fifth stacking step.

  After the fifth stacking step, a part of the resistor 50 is melted by irradiating a laser along the thickness direction so that the resistor 50 is condensed, and the resistance value of the resistor 50 is set to a desired value. Adjust to. The above is the adjustment process. The semiconductor device 100 is formed through the above steps.

  Next, feature points of the semiconductor device 100 according to the present embodiment and the functions and effects thereof will be described. As described above, the surface 35a (second interface 41) of the first insulating layer 35 is formed in a trapezoidal shape, and a hypotenuse 35b that is slanted in the thickness direction is formed on a part of the surface 35a (second interface 41). Has been. The second reflective layer 34 is uniformly laminated on the surface 35a (second interface 41), and a hypotenuse 34b that is inclined with respect to the thickness direction is formed on the surface 34a (first interface 40). Thus, a part of the first interface 40 and the second interface 41 is formed obliquely with respect to the thickness direction. Therefore, in the adjustment step, as shown by the white arrow in FIG. 1, when the resistor 50 is irradiated with laser through the protective film 70, the protective film 70, the resistor 50, and the second insulating layer 36 are transmitted. The laser incident on the first interface 40 is reflected in a direction oblique to the thickness direction at the oblique side 34b of the first interface 40, and the protective film 70, the resistor 50, the second insulating layer 36, and the second The laser beam that has passed through the reflective layer 34 and entered the second interface 41 is reflected by the oblique side 35b of the second interface 41 in a direction oblique to the thickness direction. Since the optical path length of the reflected wave reflected by the resistor 50 changes depending on the angle at which the reflected wave is reflected, reflected waves having various optical path lengths are reflected by the resistor 50. Therefore, it is possible to form a region in which the interference light due to the incident light incident on the resistor 50 and the reflected light reflected by the first interface 40 and the second interface 41 is intensified by the resistor 50. Accordingly, the resistor 50 can be stably laser-trimmed regardless of the thickness of each layer constituting the semiconductor device 100.

  In addition, as described above, the multilayer structure 30 according to the present embodiment includes the first insulating layer 35 and the first reflective layer 33, and the third interface 42 that reflects the laser at these boundaries. Is formed. Therefore, in the adjustment step, the laser that is transmitted through the first interface 40 and the second interface 41 and is incident on the semiconductor substrate 10 can be reflected at the third interface 42.

  As described above, the multilayer structure 30 according to this embodiment includes the two reflective layers 33 and 34 and the two insulating layers 35 and 36, and thus includes the three interfaces 40 to 42 that reflect the laser. Yes. Therefore, compared with a semiconductor device that includes one reflective layer and two insulating layers and thereby has two interfaces that reflect the laser, the laser is prevented from entering the semiconductor substrate 10. As a result, the occurrence of crystal defects in the semiconductor substrate 10 due to the laser incident on the semiconductor substrate 10 is suppressed, and defects such as leakage current in the elements formed in the semiconductor substrate 10 are suppressed. Therefore, since an element can be formed under the resistor 50 in the semiconductor substrate 10, an increase in the size of the semiconductor device 100 can be suppressed.

  As described above, the semiconductor device 100 according to the present embodiment is a semiconductor device in which laser trimming is stabilized and laser incidence on the semiconductor substrate is suppressed.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a sectional view showing a schematic configuration of the semiconductor device according to the second embodiment, and corresponds to FIG. 1 shown in the first embodiment. 4A and 4B are cross-sectional views for explaining the semiconductor device manufacturing method according to the second embodiment, wherein FIG. 4A shows a third stacking step and FIG. 4B shows a forming step. FIG. 4 corresponds to FIG. 2 shown in the first embodiment.

  Since the semiconductor device 100 according to the second embodiment is often in common with that according to the first embodiment, a detailed description of the common parts will be omitted below, and different parts will be described mainly. In addition, the same code | symbol shall be provided to the element same as the element shown in 1st Embodiment.

  In the first embodiment, the surface 35a (second interface 41) of the first insulating layer 35 is formed in a trapezoidal shape by anisotropic etching, and the second reflective layer 34 is evenly formed on the surface 35a (second interface 41). In the example, the first interface 40 and a part of the second interface 41 are formed to have the oblique sides 35b and 34b inclined with respect to the thickness direction. In contrast, in the present embodiment, the surface 34a (first interface 40) in the second reflective layer 34 is formed in a trapezoidal shape by anisotropic etching, and a part of the first interface 40 is in the thickness direction. It is characterized by being slanted.

  As shown in FIG. 3, the multilayer structure 30 according to the present embodiment is similar to the multilayer structure 30 according to the first embodiment, in the direction from the semiconductor substrate 10 to the resistor 50, the first reflective layer 33, the first The first insulating layer 35, the second reflective layer 34, and the second insulating layer 36 are laminated in this order, and the first interface 40 between the second insulating layer 36 and the second reflective layer 34, the second reflective layer 34, and the first reflective layer 34 are stacked. The laser incident on the multilayer structure 30 is reflected at the second interface 41 with the insulating layer 35 and the third interface 42 between the first insulating layer 35 and the first reflective layer 33. The surface 34a (first interface 40) of the second reflective layer 34 has a trapezoidal shape, whereby a part of the surface 34a (first interface 40) forms a hypotenuse 34b that is inclined with respect to the thickness direction. . The laser incident on the multilayer structure 30 is reflected by the hypotenuse 34b in a direction oblique to the thickness direction.

  Next, a method for manufacturing the semiconductor device 100 will be described. Since the first, second, fourth, and fifth stacking steps and the adjustment step are the same as those in the first embodiment, description thereof is omitted, and only the third stacking step and the forming step are described.

  After the second stacking step, as shown in FIG. 4A, the second reflective layer 34 made of silicon nitride is stacked on the surface 35a (second interface 41) of the first insulating layer 35 by the CVD method. The above is the third stacking step.

  After the third lamination step, as shown in FIG. 4B, the surface 34a (first interface 40) of the second reflective layer 34 is formed in a trapezoidal shape by anisotropic etching. Thereby, a hypotenuse 34b that is inclined with respect to the thickness direction is formed on a part of the surface 34a (first interface 40). The above is the forming process. In addition, the length along the oblique side 34b is formed longer than the wavelength of the laser irradiating the resistor 50 in the adjusting step, and thereby the laser is reflected.

  Next, feature points of the semiconductor device 100 according to the present embodiment and the functions and effects thereof will be described. As described above, the surface 34a (first interface 40) of the second reflective layer 34 is formed in a trapezoidal shape, and a hypotenuse 34b that is inclined with respect to the thickness direction is formed on a part of the surface 34a (first interface 40). Is formed. Therefore, in the adjustment step, when the resistor 50 is irradiated with a laser through the protective film 70, the laser that has passed through the protective film 70, the resistor 50, and the second insulating layer 36 and entered the first interface 40 is Reflected in a direction oblique to the thickness direction at the oblique side 34 b of the first interface 40. Since the optical path length of the reflected wave reflected by the resistor 50 changes depending on the angle at which the reflected wave is reflected, reflected waves having various optical path lengths are reflected by the resistor 50. Therefore, it is possible to form a region in which the interference light caused by the incident light incident on the resistor 50 and the reflected light reflected by the first interface 40 is intensified by the resistor 50. Accordingly, the resistor 50 can be stably laser-trimmed regardless of the thickness of each layer constituting the semiconductor device 100.

  Further, as described above, the multilayer structure 30 according to the present embodiment includes the two reflective layers 33 and 34 and the two insulating layers 35 and 36 as in the first embodiment, thereby reflecting the laser. It has three interfaces 40-42. Therefore, the semiconductor device 100 is provided with one reflective layer and two insulating layers, thereby suppressing the incidence of laser on the semiconductor substrate 10 as compared with a semiconductor device having two interfaces that reflect the laser. Yes. As a result, the occurrence of crystal defects in the semiconductor substrate 10 due to the laser incident on the semiconductor substrate 10 is suppressed, and defects such as leakage current in the elements formed in the semiconductor substrate 10 are suppressed. Therefore, similarly to the semiconductor device 100 shown in the first embodiment, since an element can be formed under the resistor 50 in the semiconductor substrate 10, an increase in the size of the semiconductor device 100 can be suppressed.

  As described above, in the semiconductor device 100 according to the present embodiment, similarly to the semiconductor device 100 shown in the first embodiment, the laser trimming is stabilized, and the incidence of laser on the semiconductor substrate is suppressed. It has become.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.

  In the present embodiment, an example in which the two reflective layers 33 and 34 are formed of silicon nitride has been described. However, the material for forming the reflective layers 33 and 34 is not limited to the above example, and any material that can reflect a laser can be used as appropriate. For example, the reflective layers 33 and 34 may be formed of aluminum. In this case, in the first stacking step, the first reflective layer 33 made of aluminum is formed on the surface 10a of the semiconductor substrate 10 by sputtering. Similarly, in the third stacking step, the second reflective layer 34 made of aluminum is formed on the surface 35a (second interface 41) of the first insulating layer 35 by sputtering.

  In the present embodiment, an example in which at least one of the first interface 40 and the second interface 41 has a trapezoidal shape is shown. However, it suffices that at least one of the first interface 40 and the second interface 41 has an oblique shape with respect to the thickness direction, and is not limited to the above example.

It is sectional drawing which shows schematic structure of the semiconductor device which concerns on 1st Embodiment. It is sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on 1st Embodiment, (a) shows a 1st lamination process and a 2nd lamination process, (b) shows a formation process, (c) is The third lamination process is shown, (d) shows the fourth lamination process, and (e) shows the fifth lamination process. It is sectional drawing which shows schematic structure of the semiconductor device which concerns on 2nd Embodiment. It is sectional drawing for demonstrating the manufacturing method of the semiconductor device which concerns on 2nd Embodiment, (a) shows the 3rd lamination process, (b) has shown the formation process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Semiconductor substrate 30 ... Multilayer structure 31 ... Reflective layer 32 ... Insulating layers 40-42 ... 1st-3rd interface 50 ... Resistors 51, 52 ... Electrode 70 ... Protective film 100 ... Semiconductor device

Claims (1)

A semiconductor substrate;
A multilayer structure in which a plurality of layers are laminated in the thickness direction of the semiconductor substrate,
A resistor laminated on the multilayer structure,
A semiconductor device in which a part of the resistor is melted by laser irradiation and the resistance value of the resistor is adjusted,
The multilayer structure includes a plurality of reflective layers that reflect the laser, a plurality of the reflective layers, and a plurality of insulating layers disposed between the reflective layer and the resistor,
At least one of the two interfaces between the reflective layer and the insulating layer at a position closest to the resistor is
In a cross section connecting the electrodes of the resistor, an upper side and a lower side along a direction substantially perpendicular to the thickness direction, an oblique side connecting the upper side and the lower side and being inclined with respect to the thickness direction, , A semiconductor device having a concavo-convex shape (hereinafter referred to as a trapezoidal shape) in which a plurality of concave shapes are connected ,
As the reflective layer, a first reflective layer and a second reflective layer, which are sequentially stacked from the semiconductor substrate in the direction of the resistor,
As the insulating layer, a first insulating layer stacked between the first reflective layer and the second reflective layer, a second insulating layer stacked between the second reflective layer and the resistor, Have
The laminated surface of the first insulating layer and the second reflective layer is formed in the trapezoidal shape in a cross section connecting the electrodes of the resistor,
The second reflective layer is laminated in accordance with the shape of the laminated surface of the first insulating layer with the second reflective layer, the laminated surface of the first insulating layer and the second reflective layer, and the second A semiconductor device , wherein a laminated surface of a reflective layer and the second insulating layer has the trapezoidal shape as the interface .

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