JP4493278B2 - Porous resin insulation film, electronic device, and method for manufacturing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an insulating film forming technique. More specifically, the present invention is useful as an insulating film in a semiconductor device and other electronic devices, and in the manufacture of an electronic device, a part of the insulating film is formed by, for example, a hard mask or etching. The present invention relates to a porous, low dielectric constant insulating film that can be used as a stopper, a CMP (chemical mechanical polishing) stopper, a metal diffusion stopper, and the like. The present invention also relates to a method for manufacturing such a porous insulating film, an electronic device provided with the porous insulating film of the present invention, and a method for manufacturing the same.
[0002]
[Prior art]
As is well known, in semiconductor devices such as LSIs and VLSIs, with the increase in the degree of integration of semiconductor integrated circuits and the improvement in element density, there is an increasing demand for semiconductor devices that are multilayered and highly integrated. However, with the high integration of semiconductor elements, the wiring interval is narrowed, and wiring delay due to increased capacitance between wirings has become a problem. This is because the wiring delay (T)) is affected by the wiring resistance (R) and the capacitance (C) between the wirings as shown in the following equation (1).
[0003]
T∝CR (1)
In the above equation (1), when the capacitance (C) between the wirings is shown in relation to the dielectric constant (ε), the following equation (2) is obtained.
C = ε0εr S / d (2)
In the above equation (2), S is an electrode area, ε0 is a vacuum dielectric constant, and d is a wiring interval.
[0004]
Therefore, in order to reduce the wiring delay (T), it is an effective means to reduce the dielectric constant of an insulating film (usually called “interlayer insulating film”) formed between multilayer wiring layers.
[0005]
In recent years, in order to meet the demand for further lowering the dielectric constant of insulating films, porous insulating films made of materials having a dielectric constant lower than 3.0, such as fluorocarbon films, porous silicones formed by sol-gel methods Membranes are being studied. Specifically, for example, semiconductor devices including a porous dielectric material layer formed from tetraethyl orthosilicate (TEOS) have been proposed (Patent Documents 1 and 2). In addition, a semiconductor device including a porous film formed by drying a wet gel film made of tetraethoxysilane by a super-seaside drying method has been proposed (Patent Document 3). That is, as a low dielectric constant material, a porous film-forming material designed to reduce the dielectric constant by forming fine voids (pores) inside the film and lowering the density of the film itself has attracted attention. I'm bathing.
[0006]
The porous film-forming material can be formed into a porous insulating film by, for example, applying the coating solution onto a substrate by, for example, spin coating, and then heating and curing (curing) it to a predetermined temperature. In addition, since the dielectric constant can be controlled by blending the materials used for preparing the coating liquid, various film-forming materials including the above-described fluorocarbon materials and silicone materials are commercially available. However, in order to actually apply such a film-forming material to a manufacturing process, for example, when a wiring layer of a semiconductor integrated circuit is formed by a dual damascene method, a low dielectric constant film and various types according to processing applications are used. It is necessary to alternately stack stoppers (for example, etching stoppers, CMP stoppers, metal diffusion stoppers, etc.). In general, the low dielectric constant film is mainly formed by the spin coat method, and the stopper is mainly formed by the CVD method. The number is increasing and becoming more complex.
[0007]
For example, in a dual damascene structure, an etching stopper is required between the wiring layer and the via layer. To form this, a low dielectric constant film is formed by spin coating, and then the stopper is formed by CVD. In addition, a film forming process of three times is required to form a low dielectric constant film again by spin coating. Further, at that time, there is a difference in thermal history between the lower dielectric constant film in the lower layer and the lower dielectric constant film in the upper layer, so that there is a problem that the low dielectric constant film is cured in the lower layer and cracks occur due to stress. Furthermore, since the low dielectric constant film is a porous film and the etching selectivity is difficult, a multi-stage hard mask is required, and therefore the number of processes is further increased. Furthermore, since there are open pores in the porous low dielectric constant film, there are many problems in application to production processes, such as problems such as poor adhesion due to degassing and electrical leakage.
[0008]
[Patent Document 1]
JP-A-8-46047 (Claims, paragraph number 0013)
[Patent Document 2]
JP-A-8-64680 (Claims, paragraph number 0011)
[Patent Document 3]
Japanese Patent Laid-Open No. 9-213797 (claims, paragraph number 0017)
˜0022, FIG. 1)
[0009]
[Problems to be solved by the invention]
An object of the present invention is to solve the problems of the conventional techniques as described above.
[0010]
An object of the present invention is to be useful as an insulating film in highly integrated semiconductor devices such as IC and LSI, and other electronic devices, and in the manufacture of electronic devices, a part of the insulating film may be used as a processing barrier. As a layer, it can be used as, for example, a hard mask, an etching stopper, a CMP stopper, a metal diffusion stopper, etc., and thus, for example, in the production of a multilayer wiring structure, the number of processing steps can be reduced and the manufacturing cost can be reduced. An object is to provide an insulating film having a low dielectric constant.
[0011]
In addition, the object of the present invention is to provide insulation as described above without problems such as cracks due to stress during film formation, problems such as adhesion failure and electrical leakage due to degassing due to open pores. It is to provide a method for producing a membrane.
[0012]
Furthermore, an object of the present invention is to provide a high-speed and highly reliable electronic device including the above-described excellent insulating film and a manufacturing method thereof.
[0013]
These and other objects of the present invention will be readily understood from the following detailed description.
[0014]
[Means for Solving the Problems]
As a result of diligent research on a method for forming a porous insulating film, the present inventors have formed a porous low dielectric constant film that can function as an insulating film with a predetermined thickness, and then formed the porous film on the porous film itself. For example, in a device manufacturing process, barrier materials that can function as masks, barriers, stoppers, etc. are preferably impregnated in the form of particles, and at least one barrier layer having different physical properties is formed inside the porous film. It was discovered that these problems could be solved simultaneously, and the present invention was completed.
[0015]
In one aspect of the present invention, a porous insulating film having fine voids throughout the film thickness,
The gap of the insulating film is derived from the fine particles of the first low dielectric constant film-forming component, and
At least one barrier layer formed from the first film-forming component and the second film-forming component having physical properties different from those of the first film-forming component is provided on at least one of the surface and the inside of the insulating film. A porous insulating film is provided.
[0016]
In another aspect of the present invention, there is provided a method for producing a porous insulating film having fine voids throughout the film thickness,
Applying a coating liquid containing a first low dielectric constant film-forming component onto a substrate;
Baking the formed coating film at a predetermined temperature to form an insulating film comprising fine particles of the first film-forming component and having the voids between the fine particles; and
Filling the gap of the insulating film with a second film-forming component having physical properties different from those of the first film-forming component, and forming the first film-forming component and at least one of the surface and the inside of the insulating film Forming at least one barrier layer formed from the second film-forming component;
In the manufacturing method of the porous insulating film characterized by comprising.
[0017]
Furthermore, the present invention, in another aspect thereof, is an electronic device comprising the porous insulating film of the present invention.
[0018]
Furthermore, the present invention, in another aspect thereof, is a method of manufacturing an electronic device including a porous insulating film having fine voids distributed substantially uniformly throughout the film thickness,
According to another aspect of the present invention, there is provided a method of manufacturing an electronic device including a step of forming the porous insulating film by the method of manufacturing a porous insulating film according to the present invention.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
The porous insulating film, the electronic device and the manufacturing method thereof according to the present invention can be advantageously implemented in various forms. In addition, each invention is not necessarily limited to the form described below.
[0020]
The present invention resides in a porous insulating film having fine voids throughout the film thickness, which is particularly useful in semiconductor devices and other electronic devices. The fine voids may be distributed almost uniformly over the entire thickness of the insulating film, or may be distributed in an arbitrary pattern. This porous insulating film is usually formed by applying a coating liquid containing an insulating film forming material on the surface of a base layer (hereinafter, generically referred to as “substrate”) such as a substrate or a wiring layer and curing it. However, other film forming methods may be used as necessary. “Electronic device” refers to various functional elements on a substrate, such as semiconductor elements such as LSI chips and VLSI chips, resistors, capacitors, conductors, electrodes, connection terminals, wiring layers, insulating layers, etc. It refers to electronic devices in general made in combination.
[0021]
The porous insulating film according to the present invention, as will be described in detail below, has the following requirements:
(1) The gap of the insulating film is derived from the fine particles of the first low dielectric constant film forming component, and
(2) At least one barrier layer formed from the first film forming component and the second film forming component having physical properties different from those of the first film forming component on at least one of the surface and the inside of the insulating film Is equipped with,
Is at least satisfied. Each requirement will be described below with reference to the accompanying drawings.
[0022]
FIG. 1 is a cross-sectional view schematically showing a preferred embodiment of a porous insulating film according to the present invention. The illustrated porous insulating film 50 is an example of a two-layer structure, and fine voids 62 are almost uniformly distributed in the thickness direction on an insulating substrate 1 such as a semiconductor substrate (for example, a silicon substrate). A caulked porous insulating layer 61 is formed. On the porous insulating layer 61, there is formed a barrier layer 71 which was originally the porous insulating layer 61 but formed by filling the gap 62 with the second film forming component according to the present invention. ing. As described in detail below, the barrier layer 71 can be used as a hard mask, a barrier, a stopper, a protective film, or the like in a manufacturing process of a semiconductor device or the like. Therefore, the barrier layer 71 may be used in a thin film state as it is depending on the purpose of use, or may be used after a part of the barrier layer 71 is selectively removed to obtain a desired thin film pattern. .
[0023]
FIG. 2 is a sectional view schematically showing another preferred embodiment of the porous insulating film according to the present invention. The illustrated porous insulating film 50 is an example of a three-layer structure. For example, a porous structure in which fine voids 62 are almost uniformly distributed in the thickness direction on an insulating substrate 1 such as a silicon substrate. Insulating layers 61-1 and 61-2 are formed apart from each other. Between these two porous insulating layers, which is originally a porous insulating layer, a barrier layer 71 formed by filling the gap 62 with the second film-forming component according to the present invention. Is formed. The barrier layer 71 is formed by impregnating the second film forming component from the upper surface of the porous insulating layer 61-2 toward the inside thereof to a predetermined depth. In the porous insulating film 50 having such a three-layer structure, when the porous insulating layer 61-2 is selectively removed, a porous insulating film having a two-layer structure as shown in FIG. 1 can be obtained. .
[0024]
The mechanism of the formation of the porous insulating film according to the present invention can be easily understood from FIG. 3 which shows the formation of the porous insulating film 50 of FIG. 2 in order.
[0025]
First, as shown in FIG. 3A, a porous insulating layer 61 made of a first low dielectric constant film forming component is formed on a substrate 51. The insulating layer 61 can be preferably formed by applying a coating liquid containing the first low dielectric constant film forming component on the substrate and baking it at a predetermined temperature. In the obtained insulating layer 61, voids 62 are formed between fine particles (not shown) of the first film forming component. The voids 62 are distributed almost uniformly in the thickness direction of the insulating layer 61. Although not shown, if a special effect is to be obtained, the hole diameter or distribution density of the void 62 may be changed in the thickness direction of the insulating layer 61.
[0026]
Next, as shown in FIG. 3B, the voids 62 of the formed porous insulating layer 61 are filled with a second film forming component 70 having physical properties different from those of the first film forming component. This filling step can be performed using a variety of techniques, as described in detail below. For example, the porous insulating layer 61 is preferably impregnated with the fine particles 70 of the second film forming component into the film by using a CVD method, a sputtering method, a vapor deposition method, or the like. Even after the second film forming component 70 is deposited on the surface of the porous insulating layer 61, the movement direction can be further maintained in the porous insulating layer 61 during the active state.
[0027]
As a result, as shown in FIG. 3C, a target porous insulating film 50 having a three-layer structure of porous insulating layer 61-1 / barrier layer 71 / porous insulating layer 61-2 is obtained. In the formation of such an insulating film having a three-layer structure, the conventional method requires a total of three film formations, but the use of the method of the present invention reduces the number to two. The formed barrier layer 71 has a higher density than the porous insulating films provided above and below it. Therefore, as various stoppers, for example, etching stoppers, CMP stoppers, metal diffusion stoppers, etc., or as mask means, for example, hard masks, etc. It can be used as it is. Furthermore, the upper porous insulating layer 61-2 can be used as a hard mask, and the number of steps can be reduced. Further, after the amount of the second film forming component particles permeated is reduced to reduce the film thickness of the barrier layer 71, the upper porous insulating layer 61-2 is removed by etching or CMP, thereby removing the surface. It is possible to provide a porous insulating film in which open pores are embedded with particles, and problems such as poor adhesion due to degassing and electrical leakage are solved.
[0028]
In FIG. 3C, a barrier layer 71 composed of a first film forming component and a second film forming component is provided inside the porous insulating film 50, but also on the surface of the insulating film 50 or A barrier layer composed of the first film-forming component and the second film-forming component can also be formed on both the surface and the inside by a similar method.
[0029]
Subsequently, the porous insulating film and the manufacturing method thereof according to the present invention will be described in more detail.
[0030]
In the porous insulating film of the present invention, in the portion other than the barrier layer, that is, in the porous insulating layer having no second film forming component, the fine particles of the first film forming component constituting the insulating layer are The fine particles preferably have a particle size smaller than the pore size of the voids formed between the fine particles. This is because if the gap is too small, the second coating film forming component is effectively infiltrated by using the gap, and a disadvantage that the target barrier layer cannot be formed occurs. The particle size of the fine particles of the first film forming component and the pore size of the voids formed between the fine particles by the fine particles are arbitrarily adjusted by selecting the type and amount of the film forming component, controlling the film forming conditions, etc. be able to.
[0031]
In addition, the barrier layer can be incorporated into the insulating film in various forms, but the fine particles of the first film forming component and the second film forming component filled in the gap formed between the fine particles. It is preferable that the structure is composed of fine particles. In particular, it is preferable to fill the voids of the fine particles of the first film forming component in such a manner as to soak the fine particles of the second film forming component. The method suitable for filling the fine particles of the second film forming component varies depending on the type of the film forming component, but generally, for example, MOCVD method, CVD method, sputtering method, vapor deposition method, etc. Include.
[0032]
In the practice of the present invention, the first film forming component may be either an inorganic material or an organic material as long as a desired porous low dielectric constant film can be formed, and is not particularly limited. . The first film-forming component is preferably an organic silicone compound fine particle.
[0033]
The organosilicone compound suitable as the first film-forming component is preferably an alkoxysilane hydrolysis product represented by the following formula (I).
[0034]
X_nSi (OR)_{Four- n}                  … (I)
In the above formula, X represents a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 8 carbon atoms, such as a methyl group, an ethyl group, or a butyl group, a fluorine-substituted alkyl group, an aryl group, a vinyl group, or the like. R is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an aryl group, a vinyl group, or the like. And n is an arbitrary integer of 0-3. Moreover, when using the organosilicone compound obtained by hydrolyzing alkoxysilane in this way, it is good to adjust the quantity of the remaining alkoxy group and the hydroxyl group which it hydrolyzed.
[0035]
The second film forming component may be any of an inorganic material and an organic material as long as a desired barrier layer can be formed in the porous insulating film, and is not particularly limited. The second film forming component is preferably a metal nitride contained in the vanadium group or the titanium group of the periodic table. Examples of suitable nitrides include, but are not limited to, for example, TaN, TiN, ZrN, HfN, etc.
[0036]
Various silicon compounds can also be used as the second film forming component. Examples of suitable silicon compounds include, but are not limited to, for example, SiO, SiO₂, SiC, SiCH, SiCN, SiON, SiN, SiOF, and SiOC.
[0037]
The porous insulating film of the present invention is preferably formed by first applying a coating liquid containing the above-described first film forming component onto a substrate, forming a film, and forming a porous insulating layer first. Can do. If necessary, the coating solution used here may contain other components.
[0038]
The film forming component is generally used by dissolving or dispersing in a solvent for forming a coating solution. Suitable solvents for forming the coating solution include, but are not limited to, those listed below, including toluene, xylene, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, cyclopentanone, and the like. These solvents may be used alone or in combination of two or more.
[0039]
The film-forming component can be used by dissolving or dispersing in various concentrations in the solvent as described above. A suitable dissolution or dispersion concentration of the film-forming component is generally about 50% by weight or more, preferably in the range of about 55-95% by weight, more preferably in the vicinity of about 90% by weight. If the amount of the film forming component is too small, a porous insulating layer having a desired void distribution cannot be formed.
[0040]
The coating liquid for forming a film may additionally contain components other than the film forming component and the solvent as necessary. Examples of the additional component include a binder and a surfactant. For example, the binder is useful as a binding aid when the molecules of the organic silicone compound are bonded together by a baking treatment or the like. Examples of suitable binders include, but are not limited to, organosilicon compounds such as tetraethoxysilane and tetraisopropoxysilane, carboxylic acid metal salts such as tin octylate and aluminum octylate, and polysilazanes. Others can be mentioned. Further, cationic, anionic, nonionic and other surfactants are suitable for preventing aggregation of fine particles.
[0041]
The coating liquid for forming a porous coating is applied to the substrate with a predetermined film thickness for film formation. Suitable coating methods are not limited to those listed below, but conventional coating methods such as spin coating, dip coating, and bar coating can be used.
[0042]
Next, the formed coating film is post-processed to obtain a porous insulating layer constituting the main body of the insulating film of the present invention. In this invention, a baking process can be used advantageously as this post-processing process. Usually, the baking step can be advantageously carried out by heating the formed coating film to a predetermined temperature after coating the coating solution on the substrate. A baking process can be implemented as follows, for example.
[0043]
First, a coating solution prepared with a predetermined composition is applied onto a substrate by a spin coating method, heated at a temperature of about 120 to 350 ° C. for about 5 to 10 minutes, and the solvent is dried. Here, if the temperature of solvent drying is less than 120 ° C., solvent drying is insufficient, and if it is 350 ° C. or higher, the performance may change due to oxidation. Next, the substrate is transferred to an inert atmosphere (for example, nitrogen gas having an oxygen concentration of 100 ppm or less) and heat-treated at a temperature of about 350 to 450 ° C. for about 30 minutes or longer. Here, it is essential that the heat treatment after the solvent drying is performed in an inert gas as described above in order to suppress oxidative decomposition, and if the heat treatment temperature is less than 350 ° C., the film is formed when the wiring is formed. There is a concern about degassing (escape of gas remaining in the film), and if it exceeds 450 ° C., cracks and the like may occur.
[0044]
In this invention, methods other than a baking process can also be used for a post-process. For example, after applying the coating liquid, the formed coating film may be irradiated with light such as ultraviolet rays, infrared rays, electron beams, X-rays, and lasers. This is because the irradiation of these lights promotes the shrinkage of the fine particles and can form voids. The use of light is also important. Although any light has a polymerization promoting effect, for example, when a target porous insulating layer is formed by causing a reaction from the surface of the coating film, it is preferable to irradiate with ultraviolet rays. This is because ultraviolet rays also have an action of promoting curing (curing) of the coating film surface and suppressing open pores. Moreover, when performing rapid temperature rising / falling control, the heating by infrared irradiation is preferable. Furthermore, when it is desired to precisely control the reaction rate, electron beam irradiation is preferred. In the case of such light irradiation, the light irradiation amount and other irradiation conditions can be arbitrarily changed according to desired results.
[0045]
Plasma treatment is also suitable as a post treatment. For example, after applying the coating liquid, the formed coating film can be irradiated with oxygen plasma or the like. This is because the irradiation of these plasmas can promote the shrinkage of the fine particles and form voids. In addition, when it is desired to perform a hydrophobic treatment on the surface of the coating, oxygen plasma irradiation is preferable. In the case of such plasma irradiation, the plasma irradiation amount and other irradiation conditions can be arbitrarily changed according to desired results.
[0046]
The insulating layer formed by the above-described method from the coating liquid for coating formation according to the present invention is preferably a porous insulating layer having fine voids distributed almost uniformly throughout the film thickness. Although this porous insulating layer and the porous insulating film including the barrier layer can be advantageously used in semiconductor devices and other electronic devices, it is advantageous as an interlayer insulating film between wiring layers particularly in semiconductor devices. Can be used for
[0047]
The porous insulating layer and the porous insulating film preferably have a dielectric constant of less than 3.0. The dielectric constant of the insulating layer and the insulating film is more preferably in the range of about 2.0 to 2.5, and most preferably about 2.2 to 2.3. Since such a low dielectric constant is obtained, when the insulating film of the present invention is used in a semiconductor device, it is possible to easily achieve a high-speed signal.
[0048]
In this invention, the porous insulating film of this invention can be obtained by introduce | transducing a barrier layer in the appropriate position of the formed porous insulating layer according to said method. Here, the thickness of the porous insulating film including the barrier layer can be changed in a wide range according to the use of the insulating film, and is not particularly limited. The thickness of the porous insulating film is preferably a low dielectric constant that can be satisfied while achieving high adhesion, which is difficult to achieve with conventional techniques, even with a relatively large thickness of 100 nm or more. And other characteristics can be realized.
[0049]
The present invention also resides in various electronic devices, typically semiconductor devices, including the porous insulating film of the present invention. Preferably, the porous insulating film is advantageously used as at least one of the insulating layers in a semiconductor device including a substrate and a plurality of insulating layers and a plurality of wiring layers that are alternately stacked on the substrate. be able to. That is, particularly in the production of a multilayer wiring structure, the porous insulating film of the present invention can be advantageously used as an interlayer insulating film.
[0050]
Furthermore, the barrier layer contained in the porous insulating film of the present invention can be advantageously used for various purposes. The barrier layer can be advantageously used particularly in a manufacturing process of a semiconductor device or the like. For example, the barrier layer in the insulating film can be advantageously used as a hard mask when the underlying layer is etched. Further, the barrier layer can be advantageously used as a stopper when etching the upper layer material, CMP, or the like. Appropriate examples of use are etching stoppers, CMP stoppers, metal diffusion stoppers and the like as described above.
[0051]
In the semiconductor device and other electronic devices of the present invention, the low dielectric constant porous insulating film according to the present invention is incorporated, and the barrier layer in the insulating film is used as a mask, barrier, stopper, etc. in the processing step. Thus, in addition to a significant reduction in wiring delay, it is possible to prevent cracks, poor adhesion, electrical leakage, etc., and to reduce the number of processes and thereby reduce manufacturing costs.
[0052]
In the electronic device of the present invention, the wiring layer can be formed advantageously from any metal wiring material. For example, the material of the metal wiring forming the wiring layer can be selected from aluminum and an alloy mainly composed of aluminum or an alloy mainly composed of copper and copper. Further, in these wiring layers, titanium or an alloy mainly composed of titanium, or an alloy mainly composed of tantalum or tantalum may be used as the barrier metal. In short, the electronic device according to the present invention has a large degree of freedom in designing the device.
[0053]
FIG. 4 shows a preferred embodiment of a semiconductor device according to the present invention. In the case of the semiconductor device 10 shown in the figure, two layers (reference numbers 3 + 4 and 8 + 9) of the porous insulating film of the present invention are incorporated therein.
[0054]
Referring to FIG. 4, the semiconductor device 10 includes a silicon substrate 1 having a transistor layer (not shown) on the upper surface. On the silicon substrate 1, an SiN diffusion preventing film 2, an interlayer insulating film (a porous insulating layer of the present invention) 3 made of siloxane resin, and SiO₂A film (barrier layer) 4 is sequentially laminated, and a Cu via 6 formed by processing these layers is also provided. A TaN film 5 is formed as a barrier metal around the Cu via 6.
[0055]
SiO₂On the film 4, an insulating film 7 made of siloxane resin is formed. Further, on this insulating film 7, an interlayer insulating film (porous insulating layer of the present invention) 8 made of siloxane resin, and SiO₂A film (barrier layer) 9 is sequentially laminated. Furthermore, a Cu embedded wiring layer 16 formed by processing these layers is also provided. A TaN film 13 is formed around the Cu buried wiring layer 16.
[0056]
In this semiconductor device, since the barrier layers 4 and 9 are incorporated on the porous insulating layer, the barrier layer can be used as an etching stopper, and the number of processes can be advantageously reduced. In addition, even when subjected to mechanical stress such as CMP in the wiring formation process or thermal stress such as baking in the semiconductor device manufacturing process, the insulating film used here has good adhesion, so Inconveniences such as this are unlikely to occur, and device characteristics and reliability can be further improved.
[0057]
FIG. 7 shows another preferred embodiment of the semiconductor device according to the present invention. In the case of the illustrated semiconductor device 20, two layers (reference numbers 24 + 25 and 31 + 32) of the porous insulating film of the present invention are incorporated therein.
[0058]
Referring to FIG. 7, the semiconductor device 20 includes a silicon substrate 21 having a transistor layer (not shown) on the upper surface. On the silicon substrate 21, SiO₂The film 22, the SiN diffusion preventing film 23, and the interlayer insulating film (porous insulating layer of the present invention) 24 made of siloxane resin are sequentially laminated. In addition, SiO₂On the film 22, a Cu buried wiring layer 27 is formed in a groove via a TaN film 26 via a SiN diffusion preventing film 23.
[0059]
On the interlayer insulating film 24, a high-density insulating film 29 made of any one of SiN, SiC, and silicon hydride (SiC: H) is further formed on the TaN film 28 on the SiN film (barrier layer) 25. It is formed between the SiN film 30. Further, the wiring connection portion 34 is formed so as to be in contact with the Cu embedded wiring layers 27 and 35. The wiring connection part 34 is made of, for example, SiO.₂, SiOC, SiOF, SiON, SiCON, SiCN, an organic insulating material, or the like. Note that the Cu buried wiring layer 35 is also formed inside the groove via the TaN film 33. Further, the Cu buried wiring layers 27 and 35 are flattened by CMP, respectively, and the side surfaces are insulated by the porous insulating films 24 and 31 according to the present invention. The porous insulating film 31 is made of a siloxane resin like the interlayer insulating film 24 and is sandwiched between the SiN film 30 and the SiN film (barrier layer) 32.
[0060]
Also in this semiconductor device, since the porous insulating film of the present invention with a barrier layer is incorporated, the same operational effects as those of the semiconductor device described above with reference to FIG. 4 can be obtained.
[0061]
The present invention also resides in a method for manufacturing an electronic device including the porous insulating film of the present invention. This manufacturing method can be basically carried out by a method generally used conventionally except for the difference in forming the porous insulating film according to the method of the present invention described above. Detailed description is omitted.
[0062]
【Example】
Subsequently, the present invention will be described with reference to examples thereof. Needless to say, the present invention is not limited to these examples.
Synthesis example
20.8 g (0.1 mol) of tetraethoxysilane was dissolved in 39.6 g of methyl isobutyl ketone. 16.2 g (0.9 mol) of nitric acid with a concentration of 400 ppm was added dropwise over 10 minutes, and after completion of the addition, an aging reaction was performed at 180 ° C. for 2 hours. Tetraethoxysilane was copolymerized to produce a spherical siloxane resin.
[0063]
Next, 11.8 g (0.1 mol) of trimethylethoxysilane was added dropwise over 10 minutes, and after completion of the addition, a aging reaction was carried out at 180 ° C. for 2 hours. Was silylated.
[0064]
Subsequently, 5 g of magnesium nitrate was added to remove excess water. The reaction solution was removed using a rotary evaporator, and freeze-dried using 1,4-dioxane.
[0065]
The obtained spherical siloxane resin was dispersed in tetrahydrofuran (THF) and fractionated by gel permeation chromatography (GPC). The GPC conditions at this time were a Tosoh column: TSKGEL-G2000HHR, a flow rate: 10 ml / min, and a detection UV wavelength: 254 nm. When the weight average molecular weights were collected around 20,000 and 2,000, spherical siloxane resins having sharp particle size distribution (referred to as fine particles A and fine particles B, respectively) were obtained. When the particle size of each fine particle was measured by a dynamic light dispersion method, the average particle size of the fine particle A was about 50 mm, and 3σ was about 15% of the average particle size with a standard deviation σ indicating the particle size distribution. Met. The average particle size of the fine particles B was about 10 mm, and 3σ was about 15% of the average particle size with a standard deviation σ indicating the particle size distribution.
[0066]
Although not synthesized here, in order to form the porous insulating film of the present invention, an organic material having heat resistance may be used instead of the inorganic fine particles as described above. As an appropriate organic material, for example, a benzene ring-containing star polymer having a small relative dielectric constant can be exemplified. In the case of this star polymer, the heat resistance can be improved by introducing a functional group into the terminal group.
Example 1
10 g of spherical siloxane resin fine particles A prepared in the above synthesis example were dissolved in methyl isobutyl ketone to obtain a coating solution (a) having a solid content concentration of 17.5% by weight. Also, 1 g of spherical siloxane resin fine particles A and 9 g of spherical siloxane resin fine particles B prepared in the above synthesis example were dissolved in methyl isobutyl ketone to obtain a coating solution (b) having a solid content concentration of 17.5 wt%. .
[0067]
Subsequently, using the coating liquids (a) and (b) prepared as described above, a porous insulating film was produced in the following procedure.
[0068]
Each coating solution was spin-coated on the surface of a silicon wafer. The rotation speed of the spin coater was 3000 rpm, and the coating time was 20 seconds. After spin coating, the solvent of the coating solution was evaporated at 200 ° C. for 10 minutes. Subsequently, the coating film formed from each coating liquid was heat-treated at 400 ° C. for 30 minutes in a nitrogen atmosphere having an oxygen concentration of 100 ppm or less. By this heat treatment, the siloxane resin was crosslinked to form a low dielectric constant porous film (film thickness: about 200 nm).
[0069]
When measuring the dielectric constant of each porous film,
Dielectric constant of coating liquid (a) ... 2.4
Dielectric constant of coating liquid (b) 2.35
And there was no big difference.
[0070]
Subsequently, SiO 2 was formed in each of the porous coating film of the coating liquid (a) and the porous coating film of the coating liquid (b) using a plasma CVD method.₂Soaked the particles. SiO₂As a result of the particles being filled into the voids of the coating, the porous coating of siloxane resin / thin and uniform SiO₂It was confirmed by an electron microscope that a three-layered porous insulating film composed of a porous film of a film / siloxane resin was formed.
Example 2
In this example, the semiconductor device shown in FIG. 4 was manufactured according to the procedure shown in order in FIGS.
[0071]
First, as shown in FIG. 5A, a SiN diffusion preventing film 2 was formed by a conventional film forming method on a silicon substrate 1 having a transistor layer (not shown) on its upper surface.
[0072]
Next, as shown in FIG. 5B, a porous siloxane resin film 3 having a thickness of, for example, 1 μm is deposited on the entire surface of the SiN diffusion preventing film 2 in accordance with the method described in the first embodiment to form an interlayer insulating film. Furthermore, on that, SiO which becomes a polishing stopper in a later CMP process₂A film (barrier layer) 4 was deposited to a thickness of 100 nm, for example. In Example 1, SiO 2₂Although the film was formed up to the inside of the siloxane resin film, in this example, the SiO film is limited to the surface of the siloxane resin film.₂The membrane was soaked.
[0073]
Subsequently, via holes reaching the source / drain regions were formed, and a TaN film 5 having a thickness of, for example, 50 nm was deposited on the entire surface by sputtering to form a barrier metal. Next, after Cu was also deposited thickly by the sputtering method, the SiO method was obtained by the CMP method.₂By polishing until the film 4 was exposed, a Cu-filled via 6 was formed.
[0074]
Next, as shown in FIG. 5C, a siloxane resin was applied to form an insulating film 7 having a thickness of 200 nm. Next, a porous siloxane resin film 8 was deposited on the insulating film 7 in a thickness of, for example, 250 nm according to the method described in Example 1. The adhesion between the insulating film 7 and the porous siloxane resin film 8 was very good. Further, on the porous siloxane resin film 8, as a CMP stopper, SiO₂A film (barrier layer) 9 was laminated.
[0075]
After the formation of the porous insulating film with the barrier layer according to the present invention is completed, SiO₂A resist was applied on the film 9 and further patterned in accordance with a via hole formed in a later step. Using the obtained resist pattern as a mask, CF₄+ CHF₃Reactive ion etching (RIE) using was performed. As shown in FIG. 5 (D), SiO₂The film 9, the siloxane resin film 8, and the insulating film 7 were selectively etched sequentially to form a via hole 11 reaching the Cu-filled via 6. After the via hole 11 is formed, the resist pattern that has become unnecessary is replaced with O.₂-Removed with RIE.
[0076]
Next, although not shown, a novolac resin is embedded in the via hole 11 formed in the previous step, and again SiO 2₂A resist was coated on the film 9 and further patterned in accordance with a wiring layer groove formed in a later step. Using the obtained resist pattern as a mask, CF₄+ CHF₃RIE using was performed. As shown in FIG. 6 (E), SiO₂The film 9 and the siloxane resin film 8 were selectively and sequentially etched to form a wiring layer groove 12 reaching the insulating film 7. After the formation of the wiring layer groove 12, the resist pattern and novolak resin that are no longer needed are replaced with O.₂-Removed with RIE.
[0077]
Next, as shown in FIG. 6F, for example, a 50 nm-thick TaN film 13 and a 50 nm-thick Cu seed layer 14 are sequentially formed on the entire upper surface of the silicon substrate 1 being processed by using a sputtering method. Deposited.
[0078]
Subsequently, electrolytic plating of copper (Cu) was performed using the Cu seed layer 14 as a plating base layer. As shown in FIG. 6G, the Cu plating layer 15 was embedded in each of the wiring layer forming groove and the via hole.
[0079]
Next, the Cu plating layer 15, the Cu seed layer 14, and the TaN film 13 were sequentially polished and removed up to the stop line C by CMP again. Base SiO₂The semiconductor device 10 (see FIG. 4) having the Cu embedded wiring layer 16 in which the film 9 was exposed and the Cu plating layer 15 and the Cu seed layer 14 were integrated was completed.
[0080]
In the semiconductor device completed as described above in this example, since the porous insulating film of the present invention is provided, it is possible to maintain stable performance without a decrease in dielectric constant due to moisture absorption, Even when subjected to mechanical stress such as CMP in the wiring formation process or thermal stress such as baking in the semiconductor device manufacturing process, film peeling is unlikely to occur due to good adhesion, and device characteristics and reliability are improved. Can be improved. Furthermore, since the insulating film is also provided with a barrier layer, the number of steps can be reduced and the manufacturing cost can be reduced.
[0081]
Further, in this example, the first via type dual damascene method is used, but the semiconductor device can be preferably manufactured also by the rear via type or single damascene method.
[0082]
Furthermore, the semiconductor device 10 of FIG. 4 has a simple structure for the description of the present invention. By repeating the insulating film forming process, the wiring layer trench and via hole forming process, and the Cu buried wiring layer forming process as many times as necessary, a semiconductor device having a more complicated structure having a multilayer wiring structure is obtained. It will be understood that Of course, the semiconductor device shown in FIG. 7 can also be easily manufactured by a method similar to this example.
Example 3
In this example, a porous insulating film having a three-layer structure was prepared according to the same method as that described in Example 1.
[0083]
After forming a siloxane resin having a void (refractive index: 1.3) with an initial film thickness of 400 nm, ZrN (refractive index: 1.9) was infiltrated into the void of the porous siloxane resin film from above by a MOCVD method. As a result, as shown in FIG.
A porous coating of a siloxane resin having a void 62 (film thickness 290 nm, refractive index 1.3) 61-1,
A ZrN-containing film (as a barrier layer, a film thickness of 20 nm, a refractive index of 1.75) 71 formed by immersing ZrN in the voids of the porous film; and
A porous coating of a siloxane resin having a void 62 (film thickness 110 nm, refractive index 1.3) 61-2,
A porous insulating film having a three-layer structure was obtained.
[0084]
Further, when a star polymer (refractive index of 1.5) was formed at an initial film thickness of 450 nm and the above-described method was repeated, a porous insulating film having a three-layer structure was obtained in the same manner.
Example 4
When the porous insulating film having the three-layer structure manufactured in Example 3 was subjected to reactive ion etching (RIE) from the upper layer side, the etching rate was
Porous coating 61-1 ... 1
ZrN-containing film 71 ... 10 or more
Porous coating 61-2 ... 1
Met.
[0085]
Similar results were obtained with a porous insulating film using a star polymer.
Example 5
When the porous insulating film having the three-layer structure manufactured in Example 3 was subjected to CMP treatment from the upper layer side, the upper porous film 61-1 was completely polished, and then the CMP was stopped by the ZrN-containing film 71. I was able to.
Example 6
In this example, a porous insulating film having a three-layer structure was prepared according to the same method as that described in Example 1.
[0086]
A siloxane resin having a void (refractive index: 1.3) is formed with an initial film thickness of 400 nm, and from above the void is formed in the porous siloxane resin film by a plasma CVD method.₂Soaked the particles. As source gas, SiH₄+ O₂The mixed gas was used. As a result, as shown in FIG.
A porous coating of siloxane resin having a void 62 (film thickness 290 nm, refractive index 1.3) 61,
SiO in the voids of the porous coating₂Formed by soaking₂Containing film (as a barrier layer, film thickness 20 nm, refractive index 1.75) 71, and
SiO₂Film (film thickness 110 nm, refractive index 1.3) 72,
A porous insulating film having a three-layer structure was obtained.
[0087]
Subsequently, when the etching process was performed by reactive ion etching (RIE) from the upper layer side of the porous insulating film by the method described in Example 4, the etching rate was:
Porous coating 61 1
SiO₂Containing film 71 4
SiO₂Membrane 72 ... 10
Met.
[0088]
Further, when the adhesion evaluation was performed for each layer of the porous insulating film, the three-layer structure of this example has a high adhesion (80 gf / cm²).
Example 7
Although the method described in Example 6 was repeated, in this example, a siloxane resin having a void (refractive index: 1.3) was formed with an initial film thickness of 400 nm, and then SiO 2 was formed from the top.₂The particles were soaked to a depth of 80 nm at different deposition rates. The deposition rate is
Sample A ... 1 nm / min
Sample B ... 5nm / min
Sample C: 10 nm / min
Sample D ... 20nm / min
Sample E: 40 nm / min
Met. As plotted in FIG. 10, it has been found that the film thickness of each layer and the deposition rate have a relationship as illustrated.
[0089]
The present invention has been described above with reference to particularly preferred embodiments and examples. Finally, the preferred embodiments of the present invention are summarized as follows for further understanding of the present invention.
[0090]
(Appendix 1) In a porous insulating film having fine voids throughout the film thickness,
The gap of the insulating film is derived from the fine particles of the first low dielectric constant film-forming component, and
At least one barrier layer formed from the first film-forming component and the second film-forming component having physical properties different from those of the first film-forming component is provided on at least one of the surface and the inside of the insulating film. A porous insulating film characterized by being provided.
[0091]
(Supplementary note 2) The porous insulating film according to supplementary note 1, wherein the fine particles of the first film-forming component have a particle size smaller than the pore size of the void formed by the fine particles. .
[0092]
(Additional remark 3) The said 1st film formation component is microparticles | fine-particles of an organosilicon compound, The porous insulating film of Additional remark 1 or 2 characterized by the above-mentioned.
[0093]
(Additional remark 4) The said barrier layer consists of the microparticles | fine-particles of the said 1st film formation component, and the microparticles | fine-particles of the said 2nd film formation component with which the space | gap formed between these microparticles | fine-particles was filled. The porous insulating film according to any one of appendices 1 to 3.
[0094]
(Additional remark 5) The said 2nd film formation component is the nitride of the metal contained in the vanadium group or titanium group of a periodic table, The porosity of any one of Additional remark 1-4 characterized by the above-mentioned. Insulating film.
[0095]
(Additional remark 6) The said 2nd film formation component is a silicon compound, The porous insulating film of any one of Additional remark 1-4 characterized by the above-mentioned.
[0096]
(Supplementary note 7) Any one of Supplementary notes 1 to 6, which has a two-layer structure including a porous insulating film made of only the first film-forming component and the barrier layer thereon. The porous insulating film according to item.
[0097]
(Additional remark 8) It has the 3 layer structure which consists of the 1st and 2nd porous insulating film which consists only of the said 1st film formation component, and the said barrier layer pinched | interposed by these porous insulating films The porous insulating film according to any one of appendices 1 to 6, characterized in that:
[0098]
(Supplementary note 9) A method for producing a porous insulating film having fine voids over the entire film thickness,
Applying a coating liquid containing a first low dielectric constant film-forming component onto a substrate;
Baking the formed coating film at a predetermined temperature to form an insulating film comprising fine particles of the first film-forming component and having the voids between the fine particles; and
Filling the gap of the insulating film with a second film-forming component having physical properties different from those of the first film-forming component, and forming the first film-forming component and at least one of the surface and the inside of the insulating film Forming at least one barrier layer formed from the second film-forming component;
A method for producing a porous insulating film, comprising:
[0099]
(Additional remark 10) The said space | gap is formed in the formation process of the said insulating film, The said space | gap is larger than the particle diameter of the fine particle of a said 1st film formation component, The manufacture of the porous insulating film of Additional remark 9 characterized by the above-mentioned. Method.
[0100]
(Supplementary note 11) In the supplementary note 9 or 10, wherein in the step of forming the barrier layer, fine particles of the second film-forming component are filled in voids formed between the fine particles of the first film-forming component. The manufacturing method of the porous insulating film of description.
[0101]
(Additional remark 12) The manufacturing method of the porous insulating film of any one of additional marks 9-11 characterized by further including the process of using the said barrier layer as an etching stopper, CMP stopper, or a metal diffusion stopper.
[0102]
(Additional remark 13) The electronic apparatus characterized by including the porous insulating film of any one of Additional remark 1-8.
[0103]
(Supplementary note 14) A method of manufacturing an electronic device including a porous insulating film having fine voids throughout the film thickness,
A method for manufacturing an electronic device, comprising the step of forming the porous insulating film by the method according to any one of appendices 9 to 12.
[0104]
(Supplementary Note 15) A plurality of insulating layers and a plurality of wiring layers are alternately stacked on a substrate to form a multilayer wiring structure, and at least one of the insulating layers is added to any one of Supplementary Notes 9 to 12. 15. The electronic device according to appendix 14, which is formed by the method described above.
[0105]
【The invention's effect】
As described in detail above, it is useful as an insulating film in highly integrated semiconductor devices such as ICs and LSIs and other electronic devices, and in the manufacture of electronic devices, a part of the insulating film is treated. As a barrier layer, it can be used as, for example, a hard mask, an etching stopper, a CMP stopper, a metal diffusion stopper, etc., and thus, for example, a porous structure that can reduce the number of processing steps and reduce the manufacturing cost in the production of a multilayer wiring structure Thus, an insulating film having a low dielectric constant can be provided.
[0106]
In addition, according to the present invention, the insulation as described above is not accompanied by problems such as cracks due to stress during film formation, and problems such as adhesion failure and electrical leakage due to degassing due to open pores. Membranes can be manufactured.
[0107]
Furthermore, according to the present invention, it is possible to provide a high-speed and highly reliable semiconductor device or other electronic device including the above-described excellent insulating film and a manufacturing method thereof. In particular, according to the present invention, the processing conditions such as the etching selection ratio and the CMP polishing ratio can be easily taken, so that the man-hour of the insulating film forming process can be reduced, and the manufacturing cost of electronic devices and the like can be drastically increased. Can be lowered.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing a preferred embodiment of a porous insulating film according to the present invention.
FIG. 2 is a cross-sectional view schematically showing another preferred embodiment of the porous insulating film according to the present invention.
3 is a cross-sectional view sequentially showing a method for forming the porous insulating film of FIG. 2;
FIG. 4 is a cross-sectional view showing a preferred embodiment of a semiconductor device according to the present invention.
5 is a cross-sectional view sequentially showing the first half of a preferred method for manufacturing the semiconductor device shown in FIG. 4;
6 is a cross-sectional view sequentially illustrating the second half of a preferred method for manufacturing the semiconductor device shown in FIG. 4;
FIG. 7 is a sectional view showing another preferred embodiment of a semiconductor device according to the present invention.
8 is a cross-sectional view of a porous insulating film having a three-layer structure manufactured in Example 3. FIG.
9 is a cross-sectional view of a porous insulating film having a three-layer structure manufactured in Example 6. FIG.
10 shows the film thickness (nm) of each layer and SiO obtained in Example 7. FIG.₂It is the graph which plotted the relationship with the deposition rate (nm / min).
[Explanation of symbols]
1 ... Silicon substrate
2 ... SiN diffusion prevention film
3 ... SiOC film
4 ... SiO₂film
7 ... Insulating film
10. Semiconductor device
13 ... TaN film
16 ... Cu embedded wiring layer
20 ... Semiconductor device
50. Porous insulating film
51 ... Board
61. Porous insulating layer
71: Barrier layer

Claims (4)

In the porous resin insulation film having fine voids throughout the film thickness,
The voids in the resin insulating film are derived from fine particles of a first low dielectric constant film forming component made of an organosilicon compound, and the first film is formed on at least one of the surface and the inside of the resin insulating film. And at least one layer formed from a second film-forming component made of a metal nitride contained in the vanadium group or the titanium group of the periodic table, having a physical property different from that of the first film-forming component. With a barrier layer , and
Porous resin wherein the barrier layer is to the microparticles of the first film-forming component, characterized Rukoto such from those of the second fine particles of the film-forming component filling the voids formed between the fine particles Insulating film. A method for producing a porous resin insulation film having fine voids over the entire film thickness,
Applying a coating liquid containing a first low dielectric constant film-forming component comprising an organic silicone compound onto a substrate;
Baking the formed coating film at a predetermined temperature to form a resin insulating film comprising fine particles of the first film-forming component and having the voids between the fine particles; and forming the first film Filling the voids of the resin insulating film with a second film forming component having a physical property different from that of the component and made of a metal nitride contained in the vanadium group or titanium group of the periodic table, Forming at least one barrier layer formed of the first film-forming component and the second film-forming component on at least one of the surface and the inside thereof,
A method for producing a porous resin insulation film, comprising:   An electronic device comprising the porous resin insulating film according to claim 1. A method of manufacturing an electronic device including a porous resin insulation film having fine voids throughout the film thickness,
A method for manufacturing an electronic device, comprising the step of forming the porous resin insulating film by the method according to claim 2 .

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