JP2000138219A - Manufacture of wiring structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a wiring structure that uses an interlayer film of an insulating organic material with less processes, without using an etching mask or etching stopper layer in an interlayer film work, nor affected by a reactive product generated through plasma processing. SOLUTION: With a first photomask 105 comprising a pattern for forming a desired via hole, a photosensitized resin layer 104 is exposed with an ultraviolet ray 106 through the first photomask 105, a first latent image 107 which is to become a via hole is formed on an electrode pad 103, and the latent image 107 is developed to form a via hole 108. Then, the photosensitized resin layer 104, where the via hole 108 is formed, is solidified to cause it to lose photosensitivity properties for forming a resin layer 109.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a wiring structure formed on a substrate constituting a semiconductor device or a display device. In particular, a via hole (through hole) or a wiring groove (trench) is formed in an interlayer insulating film, a metal film is deposited thereon, and the metal film is removed by a chemical mechanical polishing (CMP) method or the like, and the via hole is removed. And a method of manufacturing a wiring structure using a so-called single damascene method or a dual damascene method in which a metal is buried in a wiring groove.

[0002]

2. Description of the Related Art In order to operate a semiconductor device in which a plurality of elements are integrated at a high speed, it is necessary to reduce wiring resistance in order to reduce wiring delay such as connection between elements. Therefore, recently, copper (Cu) having a low resistivity and being easily available has been studied for wiring. In forming the wiring structure using Cu, the single damascene method and the dual damascene method are actively studied in order to simplify the process and reduce the cost. Less than,
Examples of conventionally developed dual damascene methods will be briefly described below.

Conventional Example 1 Document 1 (Japanese Patent Application Laid-Open No. 10-112503) describes a method of manufacturing a semiconductor device by a dual damascene method using an organic low dielectric constant film. In recent years, in a semiconductor device in which the degree of integration has been improved due to the progress of miniaturization, the distance between the wirings is closer, and therefore, in order to further reduce the wiring delay, the distance between the wirings and the wiring and the substrate have to be reduced. It is necessary to reduce the capacity between the two. Therefore, the above-mentioned organic low-dielectric-constant insulating film having a small dielectric constant and easy to process has been studied as an interlayer insulating film for separating each wiring.

[0004] The manufacturing method described in Document 1 will be described with reference to FIG. In this document 1, first, FIG.
As shown in (a), a silicon oxide film 602, an organic low dielectric constant film 603, and a silicon oxide film 604 are sequentially deposited on a silicon substrate 601, and a resist pattern 605 having a groove in a wiring structure forming portion is formed thereon. I do. Then, using the resist pattern 605 as a mask, the silicon oxide film 60 is used.
4 is etched and then the resist pattern 605 is removed to form a groove 606 in the silicon oxide film 602 as shown in FIG.

[0005] Next, as shown in FIG.
A resist pattern 607 having an opening disposed therein is formed. Then, by using the resist pattern 607 as a mask, the organic low dielectric constant film 603 and the silicon oxide film 602 are selectively etched away, and the resist pattern 607 is removed, as shown in FIG. Then, a contact hole 608 in which the surface of the silicon substrate 601 is exposed is formed at the bottom.

[0006] Next, as shown in FIG.
The organic low dielectric constant film 603 is selectively etched away using the silicon oxide film 604 on which the silicon oxide film 604 is formed as a mask to form a wiring groove 609. At this time, the lower silicon oxide film 6
No. 02 is not etched due to a difference in material, so that no groove is formed in the silicon oxide film 602, and a contact hole 608 remains. Next, a wiring material is deposited on the silicon oxide film 604 including the inside of the contact hole 608 and the wiring groove 609, and then the wiring material is removed by chemical mechanical polishing (CMP) until the silicon oxide film 604 is exposed. As a result, as shown in FIG. 6F, a wiring material 610 is formed so as to fill the contact holes 608 and the wiring grooves 609. According to the above-described steps, a wiring structure using Cu as an electrode wiring material by using an organic low-dielectric-constant film as a part of an interlayer film according to Conventional Example 1 described in Document 1 is formed.

By the way, in the above-mentioned conventional example 1, since the organic low dielectric constant film is arranged between adjacent wirings formed in the same layer, the capacitance between these wirings can be reduced. For example, the capacitance between the wiring and the substrate is not significantly reduced. Here, the following document 2 (Monthly Semiconducto)
In the technique described in r World (January 1998), pp. 108-114), an organic low dielectric constant film is used for almost all interlayer films.

Conventional Example 2 First, in one technique described in Document 2, FIG.
As shown in FIG. 2, a silicon nitride film 701 and a low dielectric constant film 70 are formed on a base layer (omitted) such as a silicon substrate.
2, a silicon oxide film 703, a low dielectric constant film 704, and a silicon oxide film 705 are sequentially deposited, and a photoresist pattern 706 having an opening at a desired position is formed.
Next, using the photoresist pattern 706 as a mask, the silicon oxide film 705, the low dielectric constant film 704, the silicon oxide film 703, and the low dielectric constant film 702 are selectively removed.
By removing the photoresist pattern 706, FIG.
As shown in (b), a via hole 707 is formed.

Next, a new photoresist is applied on the silicon oxide film 705 including the via hole 707 forming portion, and the electrode wiring pattern is exposed and developed, thereby obtaining the structure shown in FIG.
As shown in (c), a photoresist pattern 708 having a groove formed in a desired region for forming a wiring structure is formed. At this time, as shown in FIG.
The exposure amount and the development amount for forming the above-described photoresist pattern 708 are controlled so that the photoresist pattern 708 also remains at the bottom of 07. Next, the silicon oxide film 705 is selectively etched using the photoresist pattern 708 as a mask to form a groove in the silicon oxide film 705 as shown in FIG.

Next, after removing the photoresist pattern 708, a silicon oxide film 705 having a groove formed therein is removed.
The low dielectric constant film 704 is selectively removed using the mask as a mask, and the wiring groove 70 is formed in the low dielectric constant film 704 as shown in FIG.
9 is formed. At this time, no groove is formed in the low dielectric constant film 702 because the silicon oxide film 703 serves as an etching stopper. Next, using the silicon oxide film 703 in which the via hole 707 is formed as a mask, the silicon nitride film 70 is formed.
1 is selectively etched, and as shown in FIG.
A via hole 710 reaching the silicon substrate surface (not shown) under the silicon film 701 is formed.

Thereafter, by filling the via hole 710 and the wiring groove 709 with a wiring material, a wiring structure connected to the silicon substrate is formed, and the dual damascene process is completed. Compared with the above-described conventional example 1, in the conventional example 2, the silicon oxide film 7 shown in FIG.
03 (may be a silicon nitride film), and different patterns are formed on the upper and lower low dielectric constant films. That is, the second conventional example is characterized in that the silicon oxide film 703 plays a role of an etching stopper layer, and patterns of different shapes are formed on the upper and lower low dielectric constant films.

Next, a third conventional example will be described with reference to FIG. The third conventional example is an example in which a via hole and a wiring groove are formed in one layer of a low dielectric constant film. First, as shown in FIG. 8A, although not shown, a silicon nitride film 801, a low dielectric constant film 802, and a silicon oxide film 803 are sequentially deposited on a base layer such as a silicon substrate, and a via hole is formed. A photoresist pattern 804 having an opening at a location where it is to be formed is formed. Then, using the photoresist pattern 804 as a mask, the silicon oxide film 803 and the low dielectric constant film 802 are used.
Is selectively etched, and the photoresist pattern 8 is formed.
By removing 04, via holes 805 are formed as shown in FIG.

Next, a photoresist is applied, the electrode wiring pattern is exposed and developed, and as shown in FIG. 8C, a photoresist pattern 8 having a groove corresponding to a wiring forming area is formed.
06 is formed. Next, the photoresist pattern 80
6 is used as a mask, the silicon oxide film 803 is selectively etched, and as shown in FIG.
03 is a state where a groove is formed. Next, after removing the photoresist pattern 806, the low dielectric constant film 802 is selectively removed halfway using the silicon oxide film 803 in which the groove is formed as a mask, as shown in FIG.
A wiring groove 807 is formed in the low dielectric constant film 802.

Then, as shown in FIG. 8F, the silicon nitride film 801 exposed at the bottom of the via hole formed in the wiring groove 807 is removed, and as shown in FIG. A via hole 808 reaching a silicon substrate not shown is formed. After that, when a wiring material is buried in the wiring groove 807 and the via hole 808 in the same manner as in the above-described conventional example 1, the wiring connected to the silicon substrate via the via hole is formed, and the dual damascene process is completed. In the third conventional example, the interlayer insulating film is composed of one layer, and the process is simplified.

[0015]

However, the above-mentioned conventional method has the following problems. As can be seen from the above Conventional Examples 1 to 3, when a wiring structure is formed in a damascene process using a low dielectric constant film as an interlayer film, grooves and holes for forming wiring in the low dielectric constant film are often formed. It is formed using a known processing technology including a photolithography technology and an etching technology. That is, a photoresist pattern is formed on an oxide film made of an inorganic material using a photolithography technique,
An oxide film is patterned using this photoresist pattern, and the underlying low dielectric constant film is patterned using the patterned oxide film as a mask.

Since the low dielectric constant film is an organic material, it is difficult to perform selective etching using a photoresist pattern of the same organic material directly as a mask. The low dielectric constant film is formed by using this as a mask. Then, the photoresist is used only for patterning the oxide film, and is removed after finishing its role.
Further, in the above-mentioned conventional examples 1 and 2, a connection hole is formed together with a wiring groove by a damascene process (dual damascene). In order to form such different patterns, a silicon oxide film or a silicon nitride film serving as an etching stopper layer is required between the low dielectric constant films. Therefore, in the prior arts 1 and 2, the number of processes increases, and in addition, the number of manufacturing apparatuses increases, which leads to an increase in cost.

On the other hand, in Conventional Example 3, two patterns are formed without using an etching stopper layer. However, dry etching using plasma is used for processing a low dielectric constant film which is an organic material. I use it. As described above, when the processing of the organic material is performed by the plasma processing, as described in the above-described Document 2,
There is a problem that a reaction product generated by the plasma treatment has an adverse effect on a processed shape of a hole or a groove.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and uses an interlayer film made of an organic material having an insulating property without being adversely affected by reaction products generated by plasma processing. It is an object of the present invention to be able to manufacture with fewer steps than the wiring structure that has been used.

[0019]

A method of manufacturing a wiring structure according to the present invention comprises the steps of forming a resin layer made of a photosensitive organic material on a substrate, and applying a predetermined amount of ultraviolet light to a predetermined region of the resin layer. Forming a latent image in the resin layer by irradiating for a time, developing the latent image to form a concave portion in the resin layer, and forming a conductive film made of a conductive material on the resin layer including the concave portion And a step of removing the conductive film from the surface to form a wiring structure in which the concave portion is filled with the conductive material. Since manufacturing is performed as described above, the concave portion of the interlayer film in which the wiring structure is embedded is formed by a photolithography technique for directly processing the interlayer film. For example, the recess is formed on the substrate via the interlayer film formed of a resin layer. The wiring structure is placed.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. Embodiment 1 First, a first embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. The first embodiment is applied to a dual damascene method. First, FIG.
As shown in (1), a photosensitive resin is applied to the substrate 101 having the electrode pads 103 and the insulating layer 102 by spin coating or the like, and is prebaked to evaporate the solvent to dry the first layer. A photosensitive resin layer 104 is formed. The photosensitive resin constituting the photosensitive resin layer 104 is a positive resin obtained by adding a positive photosensitive agent (such as diazonaphthoquinone) to a base resin using polyimide, polyamic acid, polybenzoxazole (PBO) or the like as a substrate. Use a photosensitive resin. Needless to say, the photosensitive resin layer 104 is an insulating material, and the photosensitive resin described below has an insulating property.

With the positive photosensitive resin using PBO as a base resin, good results were obtained using, for example, CRC8300 (trade name) manufactured by Sumitomo Bakelite Co., Ltd. In the case of this CRC 8300, prebaking such as evaporating the solvent may be performed by placing the substrate coated with the substrate on a hot plate heated to 120 ° C. for about four minutes. It should be noted that such a photosensitive resin is characterized by having a low relative dielectric constant of about 2.5 to 3.0 after being cured by hard baking (high-temperature heat treatment) at about 300 ° C. Next, as shown in FIG. 1B, a first photomask 105 having a pattern for forming a desired via hole is used, and ultraviolet rays 106 are applied to the photosensitive resin layer 104 through the first photomask 105. Exposure is performed to form a first latent image 107 serving as a via hole on the electrode pad 103.

Here, this exposure step will be described in more detail. First, the first photomask 105 used is
A pattern serving as a via hole formed of a light transmitting portion is formed at a desired position, and a mask alignment mark is formed at, for example, a peripheral portion. That is, the first
In the photomask, a light-shielding film made of a metal film such as chrome is formed on a transparent substrate made of synthetic quartz, etc.
The pattern formed of the above-mentioned light transmitting portion is formed at a predetermined position of the light shielding film. Here,
Since a positive photosensitive resin is used, the pattern of the photomask is constituted by a light transmitting portion. On the other hand, when a negative photosensitive resin is used, for example, a photomask having a pattern formed of a light-shielding body made of a metal film such as chrome on a transparent substrate made of synthetic quartz or the like may be used. Good.

At the time of exposure, the pattern forming surface of the first photomask 105 is provided so as to face the photosensitive resin layer 104 forming surface. At this time, by setting the positional relationship between the substrate alignment mark formed on the substrate 101 and the above-described mask alignment mark in a predetermined state, the relative positional relationship between the substrate 101 and the first photomask 105 is set in a predetermined state. And As a result, the position of the pattern to be a via hole formed in the first photomask 105 overlaps the position where the via hole of the photosensitive resin layer 104 is to be formed. After performing the above alignment,
The first photomask 105 is irradiated with ultraviolet rays 106 from the side where the pattern is not formed, and the pattern is transferred to the photosensitive resin layer 104, whereby the first latent image 107 can be formed.

Next, the first latent image 107 is developed, and FIG.
As shown in (c), a via hole 108 is formed in the photosensitive resin layer 104. Here, in the first embodiment, since the positive type CRC 8300 is used as the photosensitive resin layer 104, a developing solution of an alkaline aqueous solution is used. In addition,
As the developing solution, one suitable for each photosensitive resin to be used is used. Next, the photosensitive resin layer 104 in which the via holes 108 are formed is cured. The curing process is a process of hardening the resin at a high temperature to cure the resin and remove the photosensitive agent. CRC830
In the case of 0, heating at 150 ° C. for 30 minutes under a nitrogen atmosphere,
Subsequently, heating is performed at a temperature of 310 ° C. to 320 ° C. for 30 minutes.

Next, as shown in FIG. 1D, a photosensitive resin is applied by spin coating or the like on the resin layer 109 which has been cured and has lost the photosensitivity, and is pre-baked to evaporate the solvent. The second photosensitive resin layer 110 is formed by drying and drying. Next, as shown in FIG. 1E, a second photomask 111 having a pattern for forming a desired electrode wiring is used, and ultraviolet rays 11 are applied to the photosensitive resin layer 110 through the second photomask 111.
2 is exposed, and a second latent image 113 serving as a groove for forming an electrode wiring is formed so as to pass over the electrode pad 103. Next, by developing the second latent image 113, the wiring groove 1 is formed in the photosensitive resin layer 111 as shown in FIG.
14 is formed. Also in this case, since the positive type CRC 8300 is used as the photosensitive resin layer 111, a developing solution of an alkaline aqueous solution is used. At this time, since the resin layer 109 has been subjected to a curing treatment, it has no photosensitivity, and
11 is hardly deformed in the exposure and development processing.

Next, a curing process is performed in the same manner as the above-described curing process for the resin layer 109, and as shown in FIG.
A via hole is arranged on the electrode pad 103, and a low dielectric constant resin layer 115 in which a wiring groove 114 is arranged so as to pass therethrough is formed. Next, as shown in FIG. 2H, a metal layer 116 is formed on the low dielectric constant resin layer 115 including the via hole 108 and the wiring groove 114 to a thickness of about 100 nm by, for example, a sputtering method. On the metal layer 116, a wiring material film 117 made of copper is formed by a plating method. However, before this plating, a thin copper film is formed as a seed layer on the surface of the metal layer 116 by a sputtering method. The wiring material 117 is not limited to copper, and aluminum, gold, silver, or the like can be used. Further, the method is not limited to the plating method, and another film forming method such as a sputtering method, a CVD method, or a flow method may be used.

The metal layer 116 is used as, for example, a barrier film for preventing diffusion of copper or the like or preventing movement of other elements. In addition, it is formed to improve the adhesion between the low dielectric constant resin layer 115 and the wiring material film 117.
Incidentally, as the metal layer 116, an optimum one may be selected depending on the type of wiring material to be used. Here, a stacked film in which a TiN film is formed on a Ti film may be used. In addition, W, which can prevent the diffusion of copper,
Other materials such as WN, Ta, and TaN may be used. As described above, when the wiring material layer 117 is formed by a plating method, the metal layer 116 can be used as a seed layer depending on a combination of materials used.

Next, as shown in FIG. 2I, a part of the metal layer 116 and the wiring material layer 117 are removed by grinding and polishing by a chemical mechanical polishing method (CMP). In a state where the via hole and the wiring groove of the layer 115 are filled with the wiring material, the electrode wiring 118 is formed by a so-called dual damascene method. Here, in CMP, a polishing solution (slurry) obtained by mixing hydrogen peroxide (H ₂ O ₂ ) with an abrasive mainly composed of alumina was used. As a result, the polishing rates of the low dielectric constant resin layer 115, the wiring material layer 117, and the metal layer 116 become substantially equal, and after the polishing is completed, the surface of the low dielectric constant resin layer 115 and the surface of the electrode wiring 118 have substantially the same height ( 0.1 μm or less).

As described above, according to the first embodiment, unlike the related art, the electrode pad 103 is formed on the electrode pad 103 as an interlayer film in a shorter process and without using plasma processing for processing the organic material. Wiring structure in which electrode wiring 118 is connected via low dielectric constant resin layer 115 (FIG. 2 (i))
Can be formed. In the first embodiment, a positive photosensitive resin is used. However, a negative photosensitive resin obtained by adding a negative photosensitive agent to polyimide or benzocyclobutene (BCB) may be used. . in this way,
When a negative photosensitive resin is used, the relationship between the light-shielding portion and the transmitting portion of the pattern of the photomask described above may be reversed.

Here, the advantages and disadvantages of using a positive type and a negative type as the photosensitive resin used as the interlayer film will be described. First, the advantage of using a positive photosensitive resin is that after development, the upper part of the hole or groove tends to open more (the edge becomes positively tapered). This is because the ultraviolet ray transmittance of the photosensitive resin layer is not 100%, so that the amount of exposure in the upper portion of the resin layer during exposure for forming a pattern is larger. In addition, the fact that the resin is melted by the development from the upper side also increases the tendency to form a positive taper. In particular, a positive photosensitive resin that increases the transmittance when irradiated with ultraviolet rays (for example, CRC8300)
Has a strong positive taper.

This positive taper is extremely important in the wiring forming process. When a material having a low resistivity such as Cu, Au, or Ag is used as a wiring material, a barrier film is formed in a hole or a groove as described above in order to suppress the diffusion of such a material into an interlayer insulating film or the like. It is necessary to put. When this barrier film is deposited by a sputtering method or a film forming method using plasma, if the holes and grooves are tapered positively, a film that is not extremely thinner than the top surface or the bottom surface is deposited on the sidewalls thereof. It is possible. However, if the taper is reversely tapered, the barrier film on the side wall must be extremely thin, causing a significant deterioration of the barrier effect.

On the other hand, in the case of a negative photosensitive resin, the mechanism for light is reversed. Therefore, if holes or grooves are formed with the negative photosensitive resin, a reverse taper is likely to occur. Therefore, when a negative photosensitive resin is used, a thick barrier film may not be formed on the side walls of holes or grooves. For this reason,
When a negative photosensitive resin is used, it is important to select a resin that does not have a taper angle as much as possible. However, in some cases, it is convenient to form a wiring structure using an inverse taper. In that case, this is not always the case. For example, when it is desired to form a gate electrode having a reverse taper, it is convenient to use a negative photosensitive resin.
A typical example of the low dielectric constant negative photosensitive resin is BCB having photosensitivity. This material has a low dielectric constant (approximately 2.
5) is obtained. The relative permittivity after curing of CRC8300, which is the positive photosensitive resin used in the first embodiment, is about 2.9.

Embodiment 2 Next, a second embodiment of the present invention will be described.
The second embodiment is a method in which the first curing treatment of the photosensitive resin in the first embodiment is replaced with a simpler treatment, and a method in which a via hole and a wiring groove can be formed by one curing treatment. is there. As described above, in the first embodiment,
In order to eliminate the photosensitivity of the first photosensitive resin layer 104 (FIG. 1C), heat treatment at a high temperature, that is, a so-called curing treatment was performed.

For this curing treatment, a heating furnace is usually used. For photosensitive resins based on polyimide, polyamic acid, PBO, BCB, etc., to prevent oxidation,
The curing treatment needs to be performed in an atmosphere of an inert gas such as nitrogen gas. Therefore, after the substrate to be subjected to the heat treatment is loaded into the heating furnace, the inside of the furnace must be purged with an inert gas for a long time. Also, the heating furnace has a large heat capacity,
Long time is required for heating and cooling. Under such circumstances, the curing process requires a long processing time. Then, after various experiments, the present inventors have found a method for quickly extinguishing the photosensitivity of the first photosensitive resin layer 104 in the above-described first embodiment by the following.

In the second embodiment, in order to quickly lose the photosensitivity of the first photosensitive resin layer 104, heat treatment is performed at a relatively low temperature in the air using a hot plate or the like. Here, FIG. 3 shows the relationship between the heat treatment temperature of the photosensitive resin film after exposure and development once, and the change in film thickness when the exposure and development treatment is performed again after the heat treatment. Here, the above-described CRC 8300 is applied, the solvent is dried by pre-baking, a photosensitive resin film is formed on the substrate, and exposure (ultraviolet light) for transferring a predetermined pattern to the photosensitive resin film is performed. The dried product was heated in the air at 150 ° C. to 210 ° C. for 10 minutes, and used as an initial state. Note that the heating was performed by placing the substrate on a hot plate at a predetermined temperature.

Then, in the photosensitive resin film in the initial state,
This time, the entire area is irradiated with the same amount of UV light,
Similarly, the film was developed and dried, and the change in the thickness of the remaining portion of the photosensitive resin film in the initial state was measured. As can be seen from FIG. 3, when the set temperature of the hot plate is 170 ° C. or higher, the film is not reduced by the second exposure and development. That is, 170 ° C using a hot plate
It can be seen that the above heating causes the photosensitivity of CRC8300 to disappear. The cause of the loss of the photosensitivity of the CRC 8300 due to this heat treatment may be, for example, evaporation of the photosensitizer, a decrease in solubility in the developer due to other chemical changes, or an influence of oxidation.

The loss of the photosensitivity due to the heating by the hot plate is not limited to the above-described CRC8300. The temperature at which the photosensitivity is lost by the heating by the hot plate depends on the type of the photosensitive resin used. Conceivable. As described above, the photosensitive resin used in the first embodiment can lose the photosensitivity without performing a high-temperature curing treatment.
It is not necessary to perform the time-consuming curing treatment of the photosensitive resin layer 104 described in (d). That is, it is sufficient that the photosensitive resin layer 104 has lost its photosensitivity at a stage before the formation of the second photosensitive resin layer 110, and the photosensitive resin film 104 needs to be cured. Because there is no.

Therefore, in Embodiment 2, FIG.
As shown in (c), after forming a via hole 108 in the photosensitive resin layer 104, about 17
The photosensitivity of the photosensitive resin layer 104 is lost by the treatment of heating to 0 ° C. or higher. Then, as shown in FIG. 1 (d), a photosensitive resin is applied by spin coating or the like on the resin layer 109 having lost the photosensitivity, and is pre-baked to evaporate the solvent, followed by drying. The second photosensitive resin layer 110 was formed. Subsequent processes are the same as in the first embodiment. As a result, according to the second embodiment, the curing process of the photosensitive resin layer 104 does not need to be performed before the formation of the photosensitive resin layer 110, so that the process time can be further reduced as compared with the first embodiment. It is possible to do.

Third Embodiment Next, a third embodiment of the present invention will be described. In the third embodiment, the wiring groove and the via hole are formed in the low-permittivity resin layer by one application, development, and hardening treatment by utilizing the photosensitive characteristics of the positive photosensitive resin.
First, as shown in FIG. 4A, a positive photosensitive resin layer 204 is formed on a substrate 201 having an electrode pad 203 or an insulating layer 202 by spin coating or the like, and is prebaked and dried. These are the same as those in the first embodiment. For example, CRC8300 manufactured by Sumitomo Bakelite Co., Ltd. was used as a positive photosensitive resin.

Next, as shown in FIG. 4B, a first photomask 205 having a pattern for forming a desired via hole is used, and the photosensitive resin layer 204 is formed through the first photomask 205. Exposure to ultraviolet rays 206 forms a first latent image 207 that partially becomes a via hole on the electrode pad 203. The photolithography technique for forming the latent image is the same as in the first embodiment. However, in forming the first latent image 207, ultraviolet rays are exposed by a later developing process in such an amount that the residual film of the positive photosensitive resin in the via hole becomes zero.

Subsequently, as shown in FIG. 4C, a second photomask 208 having a pattern for forming a desired electrode wiring is used, and a photosensitive resin is passed through the second photomask 208. UV 20 again on layer 204
9 is exposed to form a second latent image 210 serving as a groove for forming an electrode wiring so as to pass over the electrode pad 203. Here, in forming the second latent image 210, the exposed positive photosensitive resin is exposed to ultraviolet rays in an amount that leaves a desired film thickness by a later development process.

Next, a first latent image 2 formed by exposure
07 and the second latent image 210 are developed, as shown in FIG.
As shown in (2), a wiring groove 211 and a via hole 212 are formed in the photosensitive resin layer 204. Here, also in the third embodiment, the photosensitive resin layer 204 is used as a positive type CRC.
Since 8300 is used, a developing solution of an alkaline aqueous solution is used. Next, after curing the photosensitive resin layer 201, as shown in FIG. 5E, on the cured low dielectric constant resin layer 213, as in the first embodiment,
A thin metal layer 214 is formed, and a wiring material 215 is additionally formed.

Next, similarly to the first embodiment, as shown in FIG. 5F, a part of the metal layer 214 and the wiring material layer 215 are removed by CMP to remove the low dielectric constant. The electrode wiring 216 is formed by a so-called dual damascene method in a state where the via hole and the wiring groove of the resin layer 213 are filled with the wiring material. As described above, according to the method of the third embodiment, unlike the conventional method, the electrode pad has a low dielectric constant as an interlayer film in a shorter process and without using plasma processing for processing the organic material. A wiring structure in which the electrode wiring is connected via the resin layer can be formed. According to the third embodiment, the number of steps can be further reduced as compared with the first and second embodiments.

In the third embodiment, in particular, the photosensitive characteristics of a positive photosensitive resin described below are used. In other words, the positive photosensitive resin suitable for the third embodiment has a low transmittance of ultraviolet light when the ultraviolet light is not exposed because most of the exposure light is absorbed on the surface side of the resin. However, once the region has been irradiated with ultraviolet light, the transmittance of ultraviolet light is gradually increased in accordance with the amount of exposure, and sufficient irradiation of ultraviolet light allows the ultraviolet light to reach a deep portion of the positive photosensitive resin layer. And has the property of exposing to the point where ultraviolet rays reach.

Because of these characteristics, the positive photosensitive resin (CRC83) used in the first to third embodiments described above is used.
In (00), the controllability of the remaining film thickness with respect to the exposure amount is relatively good, and therefore, a desired remaining film thickness is easily obtained by development.
When this type of positive photosensitive resin is used, when the first latent image 207 is formed, the lower portion of the photosensitive resin layer 204 is exposed to ultraviolet light in an amount that is sufficiently exposed to light, and the next latent image 207 is exposed. When the second latent image 210 is formed, by exposing the photosensitive resin layer 204 to an amount of ultraviolet rays that is exposed to the middle (a desired depth), a via hole portion is formed, and at the same time, a wiring groove portion is relatively formed. It can be formed with good controllability of the film thickness.

By the way, in the third embodiment,
The exposure wavelength when forming the first latent image 207 and the second latent image 21
By changing the exposure wavelength at the time of forming 0, the controllability of the remaining film thickness with respect to the exposure amount of the resin in the second latent image 210 can be further improved. For example, the above CRC8
In the case of a 300-positive photosensitive resin, the transmittance to light having a wavelength of about 350 to 500 nm changes due to exposure to ultraviolet light. That is, the transmittance of light having a wavelength of about 350 to 500 nm is poor when not exposed to ultraviolet light, but the transmittance of light in that wavelength band is improved when the ultraviolet light is sufficiently exposed. However, the transmittance of light having a wavelength of less than about 350 nm does not improve even after exposure.

Therefore, in the third embodiment described above, first, in FIG. 4B, the first latent image 207 is formed by exposing to light using ultraviolet rays of about 350 to 500 nm. When light in this wavelength range is irradiated, the transmittance of the exposure light in the photosensitive resin layer 204 gradually increases, and the exposure light reaches the bottom, so that the bottom of the latent image 207 reaches the electrode pad 203. Can be. Then, in forming the second latent image 210, about 350 nm
Exposure is performed with ultraviolet rays in the following wavelength bands. About 350
Ultraviolet rays in a wavelength band of nm or less have poor transmittance and are not improved by exposure, so that the exposure light does not reach the inside of the photosensitive resin layer 204 very much. Therefore, if the second latent image 210 is formed by exposure to ultraviolet light having a wavelength band of about 350 nm or less, the depth of the second latent image 210 can be reduced without strictly controlling the exposure amount. It can be in a substantially constant state.

In order to change the wavelength band for exposure as described above, for example, a high-pressure mercury lamp is used as an exposure light source, and an optical filter is inserted into the optical path to selectively transmit ultraviolet light having a wavelength of 350 nm or less. What should I do? As the optical filter, there are a filter that absorbs light outside the desired wavelength band and a filter that reflects light other than the desired wavelength band. As is well known, a reflection type filter can be obtained by optically designing and creating a multilayer film in which a plurality of films having different optical constants are laminated. Note that when ultraviolet light having a very short wavelength is used when forming the second latent image, the portion irradiated with the ultraviolet light may be cured, so that the photosensitive resin layer is hardly cured in a wavelength range shorter than 350 nm. It is better to use a wavelength in a range not to be used.

In the third embodiment, a positive photosensitive resin is used. However, a negative photosensitive resin may be used. When a negative photosensitive resin is used, a latent image corresponding to the second latent image may be formed, and then a latent image corresponding to the first latent image may be formed. in this case,
First, a first negative latent image that is the reverse of the second latent image shown in FIG. 3C is formed. In the formation of the first negative latent image,
The exposure is performed by reversing the relationship between the light transmitting portion and the light shielding portion of the mask. As a result, the first negative latent image forming region other than the groove forming portion is irradiated with exposure light and hardened by light, and the first negative latent image forming region becomes insoluble in the developing solution. That is, when a negative photosensitive resin is used, for example, the wiring groove forming portion is an unexposed (unexposed) region.

If development is performed in this state, the groove forming portion other than the first negative latent image is selectively removed. However, during this development, the development time is set so that the unexposed negative photosensitive resin layer remains. Is adjusted within a shorter range than usual. As a result, a wiring groove is formed in the negative photosensitive resin layer. And this time,
A second negative latent image corresponding to the first latent image is formed. Also in the formation of the second negative latent image, exposure is performed by reversing the relationship between the light transmitting portion and the light shielding portion of the mask for forming the first latent image. As a result, the second negative latent image forming area is irradiated with the exposure light, is photo-cured, and becomes insoluble in the developing solution.

If development is performed in this state, the via-hole-forming portion other than the second negative latent image of the remaining negative photosensitive resin layer is selectively removed. As a result,
In the negative photosensitive resin layer, wiring grooves in areas other than the first negative latent image and through holes in areas other than the second negative latent image are formed. However, in the method using the negative photosensitive resin, the formation of the wiring groove is controlled by, for example, the developing time. Therefore, this method and the third embodiment described above are used.
As compared with the method using a positive photosensitive resin as described above, the controllability of forming the wiring groove is more excellent when the positive photosensitive resin is used.

In the above description, an exposure method of the same size in which a photomask is arranged close to an object to be exposed is used for forming a latent image. However, the present invention is not limited to this. A projection exposure method for projecting an image by projection or a reduced projection exposure method for projecting a reduced optical image may be used. In the above description, after forming a through hole and a wiring groove in a photosensitive resin layer as an interlayer film,
Although a so-called dual damascene process for filling them with a metal material has been described as an example, the present invention is not limited to this. Apply it to so-called single damascene, where only holes are formed and then filled with metal material to form plugs, or only wiring grooves are formed and metal material is filled there to form only wiring. You may. Even in the single damascene process, the number of processes can be reduced and the cost can be reduced as compared with the related art.

Further, for example, the electrode pad 10 shown in FIG.
3 and the presence or absence of the insulating layer 102 are not directly related to the present invention. Further, the type and shape of the substrate or the presence or absence of an integrated circuit or the like are not directly related to the present invention. Further, the application of the photosensitive resin is not limited to the spin coating, and any other method such as a spray coating method may be used as long as it can be applied to a uniform thickness. In addition, by appropriately changing the pattern of the photomask and repeating the above-described steps according to the present invention, a multilayer wiring can be easily formed. In the above embodiment, the case where a resin having a heat resistance of 300 ° C. or more is used as a substrate has been described. However, other processes for forming a wiring structure are performed at a low temperature. If heat resistance is not so high, a photosensitive resin using a resin having low heat resistance such as novolak resin as a substrate may be used.

When the organic resin layer is used as an interlayer insulating film, the stress of the film is small and cracks are unlikely to occur, so that it is possible to increase the thickness. It is possible to form one layer with a thickness of 10 μm or more. Therefore, an electrode wiring having a thickness of 10 μm or more can be formed. When a photosensitive resin having a reduced viscosity is rotated at a high speed and spin-coated, a thin photosensitive resin layer having a thickness of about 1 μm or less can be applied. In this case, if a reduced projection exposure using a short-wavelength light source is used, a fine pattern can be obtained by developing a photosensitive resin, and a multilayer wiring of a fine and highly integrated circuit using a single crystal silicon substrate can be obtained. Can also be used for the production of In this case, a significant reduction in manufacturing cost and high-speed operation of the integrated circuit are enabled. The relative permittivity of the photosensitive resin having a reduced dielectric constant is about 2.5 to 3.0, and a metal such as Cu or Au having a low resistivity is used for an electrode wiring, and the damascene or the damascene of the present invention is used. When the dual damascene process is used, a multilayer wiring excellent in high frequency characteristics, a coil having a large Q value, and the like can be formed.

[0055]

As described above, according to the present invention, the step of forming a resin layer made of a photosensitive organic material on a substrate and the step of irradiating a predetermined region of the resin layer with a predetermined amount of ultraviolet light for a predetermined time are described. Forming a latent image in the resin layer by developing the latent image, forming a concave portion in the resin layer, forming a conductive film made of a conductive material on the resin layer including the concave portion, To form a wiring structure in a state where the concave portions are filled with the conductive material by removing from the surface. Since the manufacturing is performed as described above, the groove of the interlayer film in which the wiring structure is embedded is formed by a photolithography technique that directly processes the interlayer film.
The wiring structure is arranged on the substrate via an interlayer film made of a resin layer. As a result, according to the present invention, the concave portion of the interlayer film in which the wiring structure is embedded can be formed without requiring a process other than a photolithography process such as dry etching, for example, without using an etching mask or an etching stopper layer. In addition, there is an effect that the device can be manufactured in fewer steps than a wiring structure using an interlayer film made of an organic material having an insulating property without being adversely affected by reaction products generated by the plasma processing.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a method for manufacturing a wiring structure according to a first embodiment of the present invention.

FIG. 2 is an explanatory view following FIG. 1 showing a method for manufacturing a wiring structure according to the first embodiment of the present invention.

FIG. 3 is a characteristic diagram showing photosensitivity characteristics of CRC8300.

FIG. 4 is an explanatory diagram showing a method for manufacturing a wiring structure according to a third embodiment of the present invention.

FIG. 5 is an explanatory view following FIG. 4 and showing a method of manufacturing a wiring structure according to the third embodiment of the present invention.

FIG. 6 is an explanatory view showing a method for manufacturing a wiring structure of Conventional Example 1.

FIG. 7 is an explanatory view illustrating a method for manufacturing a wiring structure of Conventional Example 2.

FIG. 8 is an explanatory view showing a method for manufacturing a wiring structure of Conventional Example 3.

[Explanation of symbols]

101: substrate, 102: insulating layer, 103: electrode pad,
104, 110: photosensitive resin layer, 105: first photomask, 106, 112: ultraviolet ray, 107: first latent image, 108: via hole, 109: resin layer, 111: second photomask, 113 ... Second latent image, 114: wiring groove, 115: low dielectric resin layer, 116: metal layer, 117
... wiring material film, 118 ... electrode wiring.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Katsuyuki Machida, Inventor F-term (reference) in Nippon Telegraph and Telephone Corporation 3-19-2 Nishishinjuku, Shinjuku-ku, Tokyo 5F033 JJ11 JJ18 JJ19 JJ21 JJ32 JJ33 JJ34 MM02 NN06 NN07 PP15 PP27 QQ37 QQ48 QQ74 RR27 SS22 TT03 XX33 5F046 AA11 AA20 BA03 CA02 CA07 CB08 NA03 NA05 NA12

Claims (13)

[Claims] A step of forming a resin layer made of a photosensitive organic material on a substrate; and forming a latent image on the resin layer by irradiating a predetermined area of the resin layer with a predetermined amount of ultraviolet light for a predetermined time. Forming a concave portion in the resin layer by developing the latent image; forming a conductive film made of a conductive material on the resin layer including the concave portion; Removing the conductive material to form a wiring structure in which the recess is filled with the conductive material. 2. The method for manufacturing a wiring structure according to claim 1, wherein said latent image is formed by irradiating a predetermined area of said resin layer with a predetermined amount of ultraviolet light for a predetermined time to reach said substrate surface. Forming a first latent image for forming the resin layer in the resin layer, and irradiating a predetermined area of the resin layer with a predetermined amount of ultraviolet light for a predetermined time to pass a portion where the opening is formed. Forming a second latent image for forming a groove extending in a predetermined direction in the resin layer. The concave portion includes the opening and the groove. Method for manufacturing a wiring structure. 3. The method of manufacturing a wiring structure according to claim 2, wherein a wavelength band of the ultraviolet light for forming the second latent image is longer than a wavelength band of the ultraviolet light for forming the first latent image. A method of manufacturing a wiring structure, wherein the wavelength band is in a wavelength band that does not easily pass through the resin layer. 4. The method for manufacturing a wiring structure according to claim 3, wherein a wavelength band for forming the second latent image is a shorter wavelength band than a wavelength band for forming the first latent image. A method of manufacturing a wiring structure. 5. The method for manufacturing a wiring structure according to claim 2, wherein the second latent image is formed after the first latent image is formed. Production method. 6. The method for manufacturing a wiring structure according to claim 1, wherein the formation of the latent image and the formation of the concave portion are performed by irradiating a predetermined area of the resin layer with a predetermined amount of ultraviolet light for a predetermined time, thereby forming a surface of the substrate. A step of forming a first latent image for forming an opening that reaches the resin layer; a step of developing the first latent image to form the opening in the resin layer; Forming a new resin layer made of a photosensitive organic material on the resin layer, and irradiating a predetermined region of the new resin layer with a predetermined amount of ultraviolet light for a predetermined time to form the opening. Forming a second latent image for forming a groove extending in a predetermined direction through the new resin layer, and developing the second latent image to form a groove on the new resin layer; Forming at least a groove, and forming the conductive film. Forming a recess comprising the opening and the groove before the step of forming the wiring structure. 7. The method of manufacturing a wiring structure according to claim 6, further comprising a step of eliminating the photosensitivity of the resin layer in which the opening is formed before forming the new resin layer. Method of manufacturing a wiring structure. 8. The method for manufacturing a wiring structure according to claim 7, wherein the photosensitivity of the resin layer is eliminated by heating the resin layer to a predetermined temperature. 9. The method for manufacturing a wiring structure according to claim 1, further comprising a step of curing the resin layer in which the concave portion is formed. 10. The method of manufacturing a wiring structure according to claim 9, wherein the curing of the resin layer is performed by heating the resin layer to a predetermined temperature. 11. The method for manufacturing a wiring structure according to claim 1, wherein a portion of the resin layer irradiated with light is removed by the development. 12. The method for manufacturing a wiring structure according to claim 11, wherein the organic material is a resin using polybenzoxazole as a substrate, and the conductive film is removed by a chemical mechanical polishing method. Method of manufacturing a wiring structure. 13. The method of manufacturing a wiring structure according to claim 2, wherein the first latent image is formed after the second latent image is formed. Production method.