JP2009010087A - Semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device which can efficiently radiate heat in a semiconductor element to the outside. <P>SOLUTION: The semiconductor device 10 is formed of an SOI substrate 11 where an element-forming substrate 11c, on which the semiconductor element 12 is formed is laminated and formed on a support substrate 11a through an embedded insulating film 11b. Since an insulating layer 13, formed of diamond whose thermal conductivity is higher than that of silicon oxide film (SiO<SB>2</SB>), is installed between adjacent semiconductor elements 12 and they are insulated and separated, the heat generated in the semiconductor element 12 can be radiated to the external part from a surface of the insulating layer 13 via the insulating layer 13. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a semiconductor device comprising a semiconductor substrate in which an element formation substrate on which a semiconductor element is formed is laminated on a support substrate via a buried insulating film.

2. Description of the Related Art Conventionally, as a semiconductor device that operates at high speed and can be highly integrated, a semiconductor device including a semiconductor substrate in which an element formation substrate on which a semiconductor element is formed is stacked on a support substrate through a buried insulating film is used. It has been.
As such a semiconductor device, for example, Patent Document 1 discloses an SOI formed by stacking an element formation substrate made of silicon on an insulating film made of silicon oxide film (SiO ₂ ) on a support substrate made of silicon. A semiconductor device is disclosed in which a semiconductor element is formed on a (Silicon on Insulator) substrate by insulating and separating with a silicon oxide film (SiO ₂ ).
JP-A-9-306920

In the semiconductor device having the above-described structure, the thermal conductivity of the silicon oxide film that insulates and isolates the semiconductor elements is as small as about 1% of the thermal conductivity of silicon. Therefore, there is a problem that the element characteristics are changed by increasing the temperature of the semiconductor element, for example, leakage current is increased.
This phenomenon is particularly noticeable when a MOSFET intended for high-speed operation or a power element intended for large current switching is used as a semiconductor element.
In recent years, a semiconductor device using a thin-film SOI substrate having an element formation substrate having a thickness of 1 μm or less having excellent characteristics such as a small leakage current has been proposed. In such a semiconductor device, Since silicon having good thermal conductivity in the semiconductor element is reduced from the conventional SOI substrate, heat generated in the semiconductor element is difficult to dissipate. For this reason, there is a problem that the above-mentioned problem appears remarkably.

  Therefore, an object of the present invention is to realize a semiconductor device that can efficiently dissipate heat generated in a semiconductor element to the outside.

In order to achieve the above object, according to the first aspect of the present invention, there is provided a semiconductor device comprising a semiconductor substrate in which an element formation substrate on which a semiconductor element is formed is laminated on a support substrate via a buried insulating film. In the apparatus, a technical means is used in which an insulating material having a thermal conductivity higher than that of the silicon oxide film (SiO ₂ ) is interposed between the adjacent semiconductor elements for insulation isolation.

According to the first aspect of the present invention, in a semiconductor device including a semiconductor substrate in which an element formation substrate on which a semiconductor element is formed is laminated on a support substrate via a buried insulating film, between adjacent semiconductor elements. In addition, since an insulator having a higher thermal conductivity than that of the silicon oxide film (SiO ₂ ) is interposed and separated, heat generated in the semiconductor element can be radiated to the outside through the insulator.
Here, since the insulator has higher thermal conductivity than a silicon oxide film (SiO ₂ ) generally used as an insulator for element isolation, heat generated in the semiconductor element can be efficiently radiated to the outside.

  According to a second aspect of the present invention, in the semiconductor device according to the first aspect, a technical means is used in which the semiconductor substrate is a thin film SOI (Silicon on Insulator) substrate.

As described in the second aspect of the present invention, the present invention can be particularly suitably used for a semiconductor device using a thin film SOI substrate in which the influence of heat generation of the semiconductor element is increased because the element formation substrate is thin.
Here, the thin film SOI substrate refers to an SOI substrate in which the thickness of the element formation substrate is 1 μm or less.

  According to a third aspect of the present invention, in the semiconductor device according to the first or second aspect, the technical means that the insulator is formed so as to reach the support substrate is used.

  According to the invention described in claim 3, since the insulator is formed so as to reach the support substrate, the heat generated in the semiconductor element is not only from the element formation substrate side, but also to the support substrate having good heat conduction. Can also dissipate heat. Thereby, the heat generated in the semiconductor element can be radiated to the outside more efficiently.

  According to a fourth aspect of the invention, in the semiconductor device according to any one of the first to third aspects, a technical means is used in which the insulator is formed of diamond.

  According to the invention described in claim 4, the insulator can be formed of diamond. Since diamond is a material having high thermal conductivity among all substances, heat generated in the semiconductor element can be radiated to the outside more efficiently.

  According to a fifth aspect of the invention, in the semiconductor device according to any one of the first to third aspects, a technical means that the insulator is formed of silicon nitride is used.

According to the invention of claim 5, the insulator can be formed of silicon nitride. Since silicon nitride is a material having a high thermal conductivity among insulators, heat generated in the semiconductor element can be radiated to the outside more efficiently.
In addition, since thinning is easy, it can be suitably used particularly for a semiconductor device including a thin film SOI substrate.

According to the invention of claim 6, in a semiconductor device comprising a semiconductor substrate in which an element formation substrate on which a semiconductor element is formed is laminated on a support substrate via a buried insulating film, between adjacent semiconductor elements, A technical means is used in which insulation is separated between adjacent semiconductor elements by interposing an electric conductor having a higher thermal conductivity than a silicon oxide film (SiO ₂ ) through an insulating film.

According to a sixth aspect of the present invention, in a semiconductor device comprising a semiconductor substrate in which an element formation substrate on which a semiconductor element is formed is laminated on a support substrate via a buried insulating film, between adjacent semiconductor elements. In addition, since a conductor having a higher thermal conductivity than that of the silicon oxide film (SiO ₂ ) is interposed and insulated through the insulating film, heat generated in the semiconductor element can be radiated to the outside via the conductor. .
Here, since the conductor has higher thermal conductivity than a silicon oxide film (SiO ₂ ) generally used as an insulator for element isolation, heat generated in the semiconductor element can be efficiently radiated to the outside.

  According to a seventh aspect of the present invention, in the semiconductor device according to the sixth aspect, the technical means that the semiconductor substrate is a thin film SOI (Silicon on Insulator) substrate is used.

As in the seventh aspect of the present invention, the present invention can be used particularly suitably for a semiconductor device using a thin film SOI substrate in which the effect of heat generation of the semiconductor element is increased because the element formation substrate is thin.
Here, the thin film SOI substrate refers to an SOI substrate in which the thickness of the element formation substrate is 1 μm or less.

  According to an eighth aspect of the invention, in the semiconductor device according to the sixth or seventh aspect, a technical means is used in which the conductor is formed so as to reach the support substrate.

  According to the eighth aspect of the present invention, since the conductor is formed so as to reach the support substrate, the heat generated in the semiconductor element is not only from the element formation substrate side but also to the support substrate having good heat conduction. Can also dissipate heat. Thereby, the heat generated in the semiconductor element can be radiated to the outside more efficiently.

  According to a ninth aspect of the present invention, in the semiconductor device according to any one of the sixth to eighth aspects, the conductor is formed of Ag or an alloy containing Ag as a main component. Use appropriate means.

  According to the ninth aspect of the present invention, the conductor can be formed of Ag or an alloy containing Ag as a main component. Since Ag or an alloy containing Ag as a main component is a material having high thermal conductivity among conductors, heat generated in the semiconductor element can be radiated to the outside more efficiently.

  According to a tenth aspect of the present invention, in the semiconductor device according to any one of the sixth to ninth aspects, a technical means is used in which the conductor is a bus line of the semiconductor device.

  As in the invention described in claim 10, the conductor can be used as a power supply bus line of the semiconductor device. In particular, Ag or an alloy containing Ag as a main component has a low resistance among conductors, and thus can be suitably used for a semiconductor device such as a CPU that requires high speed.

  According to an eleventh aspect of the present invention, in the semiconductor device according to any one of the first to tenth aspects, a technical means is used in which at least one of the semiconductor elements is a power element.

  A power device such as a lateral diffusion MOS (LDMOS) or an insulated gate bipolar transistor (IGBT) generates a large amount of heat. Therefore, as in the invention according to claim 11, a semiconductor device in which at least one of the semiconductor devices is a power device. Can be suitably used.

[First Embodiment]
A semiconductor device according to a first embodiment of the present invention will be described with reference to the drawings. Here, a semiconductor device in which a semiconductor element is formed on a thin film SOI substrate will be described as an example. FIG. 1 is a cross-sectional explanatory view of the semiconductor device of the first embodiment. FIG. 2 is an explanatory cross-sectional view illustrating a modification of the semiconductor device of the first embodiment.
In each drawing, for the sake of explanation, a part is enlarged and exaggerated.

  As shown in FIG. 1, the semiconductor device 10 includes a plurality of semiconductor elements 12 such as LDMOS and CMOS on an element formation substrate 11 c of an SOI (Silicon On Insulator) substrate 11. The insulating layer 13 is interposed and insulated and separated. Here, the semiconductor element 12 has a known configuration, and illustration and description of the internal configuration are omitted.

The SOI substrate 11 is formed by, for example, a Smart Cut method, and is a thin-film SOI substrate in which an element formation substrate 11c having a thickness of about 50 nm is stacked on a support substrate 11a via a buried insulating film 11b.
The semiconductor element 12 is formed by a known semiconductor process.

The insulating layer 13 fills the groove 11d formed by the buried insulating film 11b and the side surface 12a of each semiconductor element 12 by an insulator having a higher thermal conductivity than that of the silicon oxide film (SiO ₂ ), in this embodiment, diamond. The semiconductor elements 12 are insulated and separated.
The insulating layer 13 is formed by, for example, depositing diamond to a thickness of about 50 nm on the main surface of the SOI substrate 11 in which the groove 11d is formed, and then removing the diamond on the element formation substrate by chemical mechanical polishing (CMP) or the like. By performing the planarization, the semiconductor element 12 is formed in a shape having no step. This process is suitable when multilayer wiring is performed or when a fine pattern is formed.

In the semiconductor device 10 having the above-described configuration, heat generated by the operation of the semiconductor element 12 is transmitted to the insulating layer 13 through the side surface 12a and is radiated to the outside from the surface of the insulating layer 13.
Here, since diamond has a thermal conductivity of 10 times or more (in the case of bulk) of silicon and is a material having a high thermal conductivity among all substances, heat generated in the semiconductor element 12 is more efficiently generated by the insulating layer 13. It can dissipate heat to the outside.
In particular, in the semiconductor device 10 provided with a power element such as a lateral diffusion MOS (LDMOS) or an insulated gate bipolar transistor (IGBT) as the semiconductor element 12, the amount of heat generated in the semiconductor element 12 is large. It can be used suitably.

(Example of change)
As shown in FIG. 2, the groove 11d may be formed so as to penetrate the buried insulating film 11b and reach the support substrate 11a, and the insulating layer 13 may be formed so as to reach the support substrate 11a. According to this configuration, heat generated in the semiconductor element can be dissipated not only from the element forming substrate 11c side but also to the support substrate 11a having good heat conduction. It can dissipate heat.

The insulating layer 13 can be formed of a material other than diamond as long as the thermal conductivity is higher than that of the silicon oxide film (SiO ₂ ). For example, it can be formed of silicon nitride or aluminum oxide.
In particular, silicon nitride can be easily formed into a thin film and has a high thermal conductivity among insulating materials. Therefore, silicon nitride can be suitably used for the semiconductor device 10 using a thin film SOI substrate as the SOI substrate 11.

  As long as the insulating layer 13 is formed so as to fill the groove 11d, the surface shape is arbitrary. For example, since the surface area is increased by forming the surface uneven, the heat dissipation efficiency can be improved.

  The present invention can also be applied to the semiconductor device 10 using the SOI substrate 11 in which the element formation substrate 11c has a thickness of about 10 μm. As the support substrate 11a, a substrate formed of a substrate material such as aluminum oxide, aluminum nitride, or silicon carbide can be used. Various semiconductor elements can be used as the semiconductor element 12 regardless of whether it is a power element or a non-power element.

[Effect of the first embodiment]
(1) According to the semiconductor device 10 of this embodiment, the semiconductor device includes the SOI substrate 11 in which the element formation substrate 11c on which the semiconductor element 12 is formed is laminated on the support substrate 11a via the embedded insulating film 11b. 10, an insulating layer 13 having a higher thermal conductivity than that of the silicon oxide film (SiO ₂ ) is interposed between adjacent semiconductor elements 12 for insulation isolation, and thus heat generation in the semiconductor element 12 is generated via the insulating layer 13. It can dissipate heat to the outside.
Here, since the insulating layer 13 is made of diamond and has higher thermal conductivity than a silicon oxide film (SiO ₂ ) generally used as an insulator for element isolation, heat generation in the semiconductor element 12 is efficiently performed. It can dissipate heat to the outside.
Since the element formation substrate 11c is thin, the thin film SOI substrate in which the influence of heat generation of the semiconductor element 12 is large can be used particularly suitably for the semiconductor device 10 using the SOI substrate 11.

(2) According to the configuration in which the insulating layer 13 is formed so as to reach the support substrate 11a, the heat generated in the semiconductor element 12 is not only from the element formation substrate 11c side but also to the support substrate 11a having good heat conduction. It can dissipate heat. Thereby, the heat generated in the semiconductor element 12 can be radiated to the outside more efficiently.

[Second Embodiment]
A second embodiment of the semiconductor device according to the present invention will be described with reference to the drawings. FIG. 3 is a cross-sectional explanatory view of the semiconductor device of the second embodiment. 4 and 5 are cross-sectional explanatory views showing the manufacturing process of the semiconductor device of the second embodiment.
In addition, about the structure similar to 1st Embodiment, while using the same code | symbol, description is abbreviate | omitted.

  As shown in FIG. 3, the semiconductor device 20 of the second embodiment is different from the semiconductor device 10 of the first embodiment in that the conductive layer 22 is filled in the groove 11 d via the insulating film 21.

  The insulating film 21 is formed so as to cover the side surface 12a of the semiconductor element 12 with an insulating material. As an insulating material for forming the insulating film 21, a material that can be formed by a semiconductor process such as aluminum oxide can be used. In this embodiment, a silicon oxide film is used.

  The conductive layer 22 is formed of a conductive material so as not to have a step difference from the surface of the semiconductor element 12. The conductive material for forming the conductive layer 22 has higher thermal conductivity than the silicon oxide film, and Al, an alloy containing Al as a main component, a low-K material having a low dielectric constant, or the like can be used. In the present embodiment, Cu or an alloy containing Cu as a main component is used as the conductive material for forming the conductive layer 22.

  In the semiconductor device 20 having the above-described configuration, since the insulating layer 21 is interposed and insulated through the conductive layer 22 having a higher thermal conductivity than the silicon oxide film, the semiconductor element 12 generates heat through the conductive layer 22. Can be radiated to the outside.

  Here, the conductive layer 22 can also have an effect other than the heat dissipation member. For example, the conductive layer 22 can be used as a shield layer against noise or charging for preventing crosstalk between adjacent semiconductor elements 12 or a power supply bus line. it can.

A method for manufacturing the semiconductor device 20 will be described with reference to FIGS.
First, as shown in FIG. 4A, an oxide film 31, a nitride film 32, and an AP-silicon oxide film 33 are stacked in this order on the surface of the SOI substrate 11 by a known method.

  Next, as shown in FIG. 4B, the oxide film 31, the nitride film 32, and the AP-silicon are formed by photolithography so that a portion corresponding to the shape of the groove 11d formed in the subsequent process is opened. The oxide film 33 is patterned.

  Subsequently, as shown in FIG. 4C, trench etching is performed on the element formation substrate 11c using the oxide film 31, the nitride film 32, and the AP-silicon oxide film 33 in which the opening is formed as a mask, thereby forming the element. A groove 11d is formed in the substrate 11c.

  Subsequently, as shown in FIG. 5A, the side surface of the groove 11d, that is, the side surface 12a of the semiconductor element 12 is oxidized by thermal oxidation to form an insulating film 21 made of a silicon oxide film.

  Subsequently, as shown in FIG. 5B, Cu is filled into the groove 11d and the space above the groove 11d by a known method such as sputtering, vapor deposition, or electrolytic plating.

Then, as shown in FIG. 5C, the oxide film 31, the nitride film 32, the AP-silicon oxide film 33, and the Cu above the element formation substrate 11c are removed by chemical mechanical polishing (CMP) and planarized. By doing so, the conductive layer 22 is formed.
Through the above-described steps, the semiconductor device 20 can be manufactured by applying predetermined wiring or the like.

(Example of change)
The surface shape of the conductive layer 22 is arbitrary as long as it is formed by filling the groove 11d. For example, since the surface area is increased by forming the surface uneven, the heat dissipation efficiency can be improved.

  The groove 11d may be formed so as to penetrate the buried insulating film 11b and reach the support substrate 11a, and the conductive layer 22 may be formed so as to reach the support substrate 11a. At this time, the insulating film 21 is also formed on the bottom of the groove 11d. According to this configuration, heat generated in the semiconductor element can be dissipated not only from the element forming substrate 11c side but also to the support substrate 11a having good heat conduction. It can dissipate heat.

  When the conductive layer 22 is made of Ag or an alloy containing Ag as a main component, it is a material having a high thermal conductivity among the conductors. Therefore, heat generated in the semiconductor element 12 can be radiated to the outside more efficiently. Further, since Ag or an alloy containing Ag as a main component has a low resistance among conductors, it is preferable to use the conductive layer 22 as a bus line for a semiconductor device 20 that requires high speed such as a CPU. it can.

  In the case where Al or an alloy containing Al as a main component is used as the conductive layer 22, in the step shown in FIG. 5B instead of the step shown in FIG. After filling the voids with Al or an alloy containing Al as a main component, the oxide film can be formed at the interface with the semiconductor element 12 by thermal oxidation. This oxide film acts as the insulating film 21.

[Effects of Second Embodiment]
(1) According to the semiconductor device 20 of the second embodiment, a semiconductor including the SOI substrate 11 in which the element formation substrate 11c on which the semiconductor element 12 is formed is stacked on the support substrate 11a via the embedded insulating film 11b. In the apparatus 20, the conductive layer 22 having a higher thermal conductivity than the silicon oxide film (SiO ₂ ) is interposed between the adjacent semiconductor elements 12 via the insulating film 21. The heat generated in the semiconductor element 12 can be radiated to the outside, and the same effect as the semiconductor device 10 of the first embodiment can be obtained.

(2) According to the configuration in which the conductive layer 22 is formed of Ag or an alloy containing Ag as a main component, since the alloy containing Ag or Ag as a main component is a material having a high thermal conductivity among conductors, Heat generated in the element 12 can be radiated to the outside more efficiently.

(3) The conductive layer 22 can be used as a power supply bus line of the semiconductor device 20. In particular, Ag or an alloy containing Ag as a main component has a low resistance among conductors, and thus can be suitably used for a semiconductor device 20 such as a CPU that requires high speed.

[Other embodiments]
As the SOI substrate 11, a strained silicon substrate in which a SiGe layer is provided between the buried insulating film 11b and the element formation substrate 11c and strain is introduced into the element formation substrate 11c can be used. Since SiGe has low thermal conductivity and poor heat dissipation, the present invention can be suitably applied.

1 is a cross-sectional explanatory view of a semiconductor device according to a first embodiment. It is a cross-sectional explanatory view showing a modification of the semiconductor device of the first embodiment. It is a section explanatory view of the semiconductor device of a 2nd embodiment. It is sectional explanatory drawing which shows the manufacturing process of the semiconductor device of 2nd Embodiment. It is sectional explanatory drawing which shows the manufacturing process of the semiconductor device of 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 20 Semiconductor device 11 Thin-film SOI substrate 11a Support substrate 11b Embedded insulating film 11c Element formation substrate 12 Semiconductor element 13 Insulating layer 21 Insulating film
22 Conductive layer

Claims (11)

In a semiconductor device comprising a semiconductor substrate in which an element formation substrate on which a semiconductor element is formed is laminated on a support substrate via a buried insulating film,
A semiconductor device characterized in that an insulating material having a higher thermal conductivity than that of a silicon oxide film (SiO ₂ ) is interposed between the adjacent semiconductor elements for insulation isolation.   The semiconductor device according to claim 1, wherein the semiconductor substrate is a thin film SOI (Silicon on Insulator) substrate.   The semiconductor device according to claim 1, wherein the insulator is formed so as to reach the support substrate.   4. The semiconductor device according to claim 1, wherein the insulator is made of diamond.   The semiconductor device according to claim 1, wherein the insulator is made of silicon nitride. In a semiconductor device comprising a semiconductor substrate in which an element formation substrate on which a semiconductor element is formed is laminated on a support substrate via a buried insulating film,
Insulating separation is performed between the adjacent semiconductor elements with a conductor having higher thermal conductivity than the silicon oxide film (SiO ₂ ) interposed between the adjacent semiconductor elements via an insulating film. Semiconductor device.   The semiconductor device according to claim 6, wherein the semiconductor substrate is a thin-film SOI (Silicon on Insulator) substrate.   The semiconductor device according to claim 6, wherein the conductor is formed to reach the support substrate.   9. The semiconductor device according to claim 6, wherein the conductor is made of Ag or an alloy containing Ag as a main component.   The semiconductor device according to claim 6, wherein the conductor is a bus line of the semiconductor device.   The semiconductor device according to claim 1, wherein at least one of the semiconductor elements is a power element.

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