JP3160545B2 - Method of forming embedded wiring - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method of manufacturing a semiconductor integrated circuit device in which a wiring is formed in a through hole, a contact hole or a concave portion such as a concave groove of an insulating film deposited on a substrate such as a semiconductor substrate or an insulating substrate. The present invention relates to a buried wiring forming method for forming plugs and wiring by burying metal for use.

[0002]

2. Description of the Related Art In recent years, as a method of forming a buried wiring, after forming a recess such as a through hole, a contact hole or a concave groove in an insulating film on a substrate, a conductive material is deposited over the entire surface to form a conductive film. After forming a film, the conductive film deposited in the region other than the concave portion is subjected to chemical mechanical polishing (CMP).
There has been proposed a method of forming a plug or a wiring in a concave portion of an insulating film by removing the plug or the wiring by a removal method. In this specification, plugs and wires embedded in an insulating film on a substrate are collectively referred to as embedded wires.

Hereinafter, the conventional method of forming a buried interconnect will be described with reference to FIGS. 8 (a) and 8 (b), taking a case where a plug is formed in a through hole formed in an insulating film as an example.

First, as shown in FIG. 8A, a silicon oxide film (hereinafter simply referred to as an oxide film) 2 having a thickness of, for example, 1 μm as an insulating film is deposited on a semiconductor substrate 1 and then oxidized. A through hole 3 having a diameter of, for example, 0.8 μm penetrating the oxide film 2 is formed in a predetermined region of the film 2 by a dry etching method. Next, oxide film 2 including through hole 3
A 30-nm-thick titanium film 4 as a lower conductive film and a 100-nm-thick titanium nitride film 5 as an intermediate conductive film are sequentially deposited over the entire surface by a PVD method. A tungsten film 6 having a thickness of 1 μm as an upper conductive film is deposited over the entire surface by CVD. Thus, a conductive film having a three-layer structure is deposited. In this case, the titanium film 4 and the titanium nitride film 5 constitute a base film.

Next, a chemical mechanical polishing method is performed by using an abrasive containing alumina as abrasive particles and iron nitrate, potassium iodate or hydrogen peroxide as an oxidizing agent,
As shown in FIG. 8B, by removing the tungsten film 6, the titanium nitride film 5, and the titanium film 4 deposited in the region other than the through hole 3, the oxide film 2 in the region other than the through hole 3 is removed. Fully exposed, through hole 3
A plug 7 made of tungsten is formed therein. In this case, when the above-described polishing agent is used, the polishing rate for the oxide film 2 is smaller than the polishing rate for the tungsten film 6, the titanium nitride film 5, and the titanium film 4, so that the oxide film 2 is not used.
Is a polishing stopper, so that the end point of polishing can be detected. Not only when forming the plug 7 made of tungsten, but also when forming a plug or wiring made of aluminum or copper, the polishing rate for the conductive film such as aluminum or copper is higher than the polishing rate for the oxide film. Since a large abrasive is used, the oxide film also serves as a polishing stopper.

[0006]

However, for example, the polishing rate for a three-layer conductive film is not uniform in the substrate surface due to variations in the pressing force for pressing the semiconductor substrate against the polishing pad in the substrate surface. Absent. In addition, since the thickness of the conductive film on the semiconductor substrate also varies, the insulating film made of an oxide film is not simultaneously exposed over the entire surface of the substrate during polishing. Exposure is slow in the area. That is, the insulating film is exposed in a certain region, but the conductive film may still remain in another region. If the conductive film remains on the insulating film, metal wires formed of aluminum or the like formed on the insulating film are short-circuited.

Therefore, in order to prevent a situation in which metal wirings are short-circuited, it is necessary to completely remove the conductive film by allowing sufficient polishing time for the conductive film on the insulating film.

However, as described above, since the polishing rate for the conductive film is higher than the polishing rate for the insulating film, the polishing pressure applied to the surface of the insulating film in the pattern region where many plugs and wirings are formed is limited. The polishing pressure is larger than the polishing pressure applied to the surface of the insulating film in the non-pattern region where almost no plugs and wirings are formed. For this reason, in the pattern region of the insulating film, the polishing rate is higher than that in the non-pattern region, so that the insulating film is unlikely to become a polishing stopper. Therefore, as shown in FIG. 8B, the insulating film is more polished in the pattern region (the right region in FIG. 8) than in the non-pattern region (the left region in FIG. 8). The phenomenon that the surface of the insulating film becomes concave is called insulating film erosion.

The erosion of the insulating film appears more remarkably as the proportion of the area occupied by the plug or wiring in the pattern region increases, and the film thickness of the pattern region in the insulating film becomes smaller than that of the non-pattern region. Also,
The degree of the insulating film erosion depends on the length of time during which polishing is continued after the insulating film is exposed in the pattern region. Therefore, when the polishing rate for the conductive film is not uniform in the substrate surface, a thickness difference of about several hundred nm may occur in the insulating film.

As described above, when the plug 7 made of tungsten is formed by the chemical mechanical polishing method, the titanium film 4, the titanium nitride film 5, and the tungsten film 6 sequentially deposited on the oxide film 2 are polished. The oxide film 2 is completely exposed by using an abrasive containing iron nitrate, potassium iodate, or hydrogen peroxide as an oxidizing agent while containing alumina as particles. Since the polishing rate for the film 2, for example, the plasma TEOS film, is about one third or less of the polishing rate for the tungsten film 6, the oxide film 2 serves as a polishing stopper.

On the other hand, it is considered that the polishing rate for the oxide film 2 and the polishing rate for the tungsten film 2 are made equal, but this makes it difficult to detect the end point of polishing. Even if the end point can be detected by a change in the rotation torque of the surface plate or the like, the oxide film 2 may be greatly polished because the polishing rate for the oxide film 2 is high.

Therefore, even if the end point of polishing is detected, the oxide film is greatly polished over the entire surface of the substrate due to the high polishing rate against the oxide film, and the polishing rate is not uniform within the substrate surface. In order to avoid the two problems of the large variation in the thickness of the oxide film, the polishing agent has been developed in a direction in which the polishing rate for the oxide film is sufficiently smaller than the polishing rate for the tungsten film. Even in mass production, there is a high possibility that an abrasive having such a polishing rate selection ratio will be used.

FIG. 9 includes alumina as abrasive particles,
FIG. 10 shows an example of oxide film erosion when a plug made of tungsten is formed in an oxide film by performing chemical mechanical polishing using an abrasive containing potassium iodate as an oxidizing agent. Including
An example of oxide film erosion when a plug made of tungsten is formed in an oxide film by performing chemical mechanical polishing using an abrasive containing iron nitrate as an oxidizing agent is shown.
9 and 10, the hole pattern region indicates a region where the area of the plug made of tungsten is about 10% of the area of the oxide film, and the non-pattern region indicates the area of the oxide film. The area occupied by the plug made of tungsten is 0%.

As shown in FIGS. 9 and 10, oxide erosion occurs in the hole pattern region.
Although the oxide film erosion is smaller in the case shown in FIG. 10 than in the case shown in FIG. 9, a peculiar phenomenon, that is, a phenomenon in which the film thickness is extremely reduced at the periphery of the hole pattern region occurs. This is considered to be due to the fact that the particle size of alumina used in the case of iron nitrate is smaller than the particle size of alumina in the case of other oxidizing agents. Therefore, also in the case shown in FIG. 10, the oxide film erosion at the peripheral portion of the hole pattern region becomes a problem.

The following problem occurs when large oxide film erosion occurs. That is, since the heights of the plug and the oxide film vary in the substrate plane, wiring capacitance or resistance variation occurs. Further, when erosion of the oxide film occurs locally, the cross-sectional area of the wiring made of aluminum or the like deposited on the oxide film decreases in the erosion portion, thereby increasing the resistance and lowering the reliability. Further, when the wiring is formed on the oxide film, the height (that is, the cross-sectional area) of the wiring decreases, so that the wiring resistance increases, the reliability decreases, and the resistance varies.

Further, since the polishing rate is relatively high in the pattern area, and the polishing rate is relatively low in the non-pattern area, the non-pattern area is maintained even after the plug or wiring is exposed in the pattern area. Polishing must be continued for the remaining conductive film,
Since the oxide film in the pattern region is mechanically polished by alumina particles contained in the polishing agent for a long time, the surface of the oxide film in the pattern region has a diameter of several 10 μm, Many large scratches (called micro scratches) having a depth of about several tens to several hundreds of nm are generated. If a wiring made of aluminum or the like is formed on the scratched oxide film, the wiring resistance increases and the device reliability decreases.

Therefore, silica is contained as abrasive particles, and p
A method has been proposed in which the oxide film is slightly secondary-polished using an abrasive containing potassium hydroxide or the like as an H adjuster to smooth the surface of the oxide film. However, scratches cannot be completely eliminated by slight secondary polishing.

In view of the foregoing, it is an object of the present invention to reduce the erosion of an insulating film and to prevent the surface of the insulating film from being scratched.

[0019]

In order to achieve the above object, the present invention relates to a method of forming a buried wiring made of a plug or a wiring in an insulating film, the material of the upper conductive film serving as the plug or the wiring. A first polishing step using a polishing agent such that the polishing rate for the lower conductive film is lower than the polishing rate for the upper conductive film, utilizing the fact that the material of the lower conductive film serving as the base film is different. After that, the second polishing step is performed using a polishing agent having a polishing rate for the lower conductive film that is about the same or higher than the polishing rate for the insulating film. That is, the conventional primary polishing is performed separately in a first polishing step and a second polishing step. Therefore, after the second polishing step is completed, secondary polishing similar to the conventional one may be performed.

The method for forming an embedded wiring according to the present invention comprises:
An insulating film depositing step of depositing an insulating film on a substrate, a concave part forming step of forming a concave part in a region where a plug or a wiring is formed in the insulating film, and a lower conductive film in a region including the concave part on the insulating film An upper conductive film deposition step of depositing an upper conductive film made of a main material of a plug or a wiring in a region including the recess on the lower conductive film; and For the film, the upper conductive film is formed in a region of the concave portion by using a first polishing agent having a polishing rate selectivity in which the polishing rate for the lower conductive film is smaller than the polishing rate for the upper conductive film. A first polishing step of performing chemical mechanical polishing so that the lower conductive film remains while removing except for,
For the lower conductive film, the lower conductive film is formed in the concave portion by using a second abrasive having a polishing rate for the lower conductive film that is substantially equal to or higher than the polishing rate for the insulating film. A second polishing step of performing chemical mechanical polishing such that the insulating film remains while removing the insulating film completely except for the region.

According to the method of forming an embedded wiring according to the present invention, the pressing force for pressing the substrate against the polishing pad varies within the substrate surface, and the thickness of the upper conductive film varies. Even when the portion where the lower conductive film is exposed and the portion where the upper conductive film remains when the conductive film is polished are mixed and the total thickness of the upper conductive film and the lower conductive film varies, the first In the polishing step, the polishing is performed using the first abrasive having a polishing rate selection ratio in which the polishing rate for the upper conductive film is higher than the polishing rate for the lower conductive film. While the speed is reduced, the polishing rate for the remaining upper conductive film is increased.

In the second polishing step, polishing is performed using a second polishing agent having a polishing rate selection ratio in which the polishing rate for the lower conductive film is substantially equal to or higher than the polishing rate for the insulating film. Therefore, the pattern region where many plugs and wirings are formed and the non-pattern region where few plugs and wirings are formed are polished at approximately the same polishing rate.

In the method for forming an embedded wiring according to the present invention, the first polishing agent in the first polishing step may have a polishing rate for the insulating film of one third or less of a polishing rate for the upper conductive film. It is preferable to have a polishing rate selection ratio as follows.

In the method for forming a buried wiring according to the present invention, the first polishing agent may have a polishing rate selected from the group consisting of a polishing rate for the lower conductive film and a polishing rate for the upper conductive film which are not more than half of the polishing rate for the upper conductive film. Preferably, it has a ratio.

In the method for forming an embedded wiring according to the present invention, it is preferable that the second abrasive has a polishing ability for the upper conductive film.

In the method for forming a buried interconnect according to the present invention, the second polishing agent has a polishing rate selection ratio at which the polishing rate for the upper conductive film is three times or less the polishing rate for the insulating film. Is preferred.

In the method for forming a buried interconnect according to the present invention, it is preferable that in the first polishing step, chemical mechanical polishing is performed until the upper conductive film is completely removed except for the region of the concave portion.

The method for forming an embedded wiring according to the present invention comprises:
Further comprising an intermediate conductive film depositing step of depositing an intermediate conductive film in a region including the recess on the lower conductive film, between the lower conductive film depositing step and the upper conductive film depositing step; Preferably, the first polishing step includes a step of removing the conductive film of the intermediate layer except for a region of the concave portion.

In this case, it is more preferable that the second polishing agent has a polishing rate selection ratio in which the polishing rate for the conductive film of the intermediate layer is higher than the polishing rate for the conductive film of the lower layer.

In the above case, it is more preferable that in the first polishing step, chemical mechanical polishing is performed until the conductive film of the intermediate layer is completely removed except for the region of the concave portion.

In the method of forming an embedded wiring according to the present invention, the lower conductive film is a titanium film and the upper conductive film is a tungsten film, and the first polishing agent in the first polishing step is It is preferable that alumina or silica is contained as abrasive particles and iron nitrate or potassium iodate is contained as an oxidizing agent.

In the method of forming a buried interconnect according to the present invention, the insulating film is a silicon oxide film and the lower conductive film is a titanium film, and the second polishing agent in the second polishing step is: It is preferable to include silica as abrasive particles and ammonium hydroxide or potassium hydroxide as a pH adjuster.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, as a method of forming a buried wiring according to an embodiment of the present invention, a method of forming a plug made of tungsten in an insulating film made of an oxide film will be described with reference to FIGS. 1 (a) to 1 (c). I will explain while.

(Conductive Film Deposition Step) First, as shown in FIG. 1A, an oxide film 12 having a thickness of, for example, 1.2 μm as an insulating film is deposited on a semiconductor substrate 11 by, for example, a CVD method. Next, after forming a resist pattern having an opening in the plug formation region on the oxide film 12, the oxide film 12 is etched using the resist pattern as a mask. A through hole 13 of 5 μm is formed, and then the resist is removed. Note that a contact hole may be used instead of the through hole 13. The through hole means a hole for connecting an upper wiring and a lower wiring, and the contact hole means a hole for connecting a wiring and a substrate.

Next, the oxide film 12 including the through holes 13
A 30 nm-thick titanium film 14 as a lower conductive film and a 100 nm-thick titanium nitride film 15 as an intermediate conductive film are sequentially deposited over the entire surface by, eg, PVD. Thereafter, a tungsten film 16 having a thickness of 600 nm as an upper conductive film made of tungsten as a main plug material is deposited over the entire surface by, for example, a CVD method. Incidentally, the titanium nitride film 15 is the tungsten film 1.
6 is deposited to prevent mutual diffusion of tungsten (6) and aluminum of the lower layer aluminum wiring (in the case of a contact hole, mutual diffusion of tungsten and silicon of the substrate). The titanium nitride film 15 is deposited to improve the adhesion to the oxide film 12. In the case of the contact hole, in addition to the improvement of the adhesion, the contact hole has a function of reducing the contact resistance between the tungsten and the substrate. That is, the titanium nitride film 15 has a function as a barrier layer, and the titanium film 1
4 has a function as an adhesion layer.

(First Polishing Step) Next, the tungsten film 1 and the titanium nitride film 15 are
The first polishing step is performed by using a polishing agent whose polishing rate for No. 6 is higher than the polishing rate for the titanium film 14,
As shown in FIG. 1B, while leaving the titanium film 14, the tungsten film 16 and the titanium nitride film 15 deposited outside the through hole 13 are removed. In the first polishing step, the tungsten film 16 and the titanium nitride film 15 may remain to some extent, or the oxide film 12
May be slightly exposed partially.

Examples of the polishing agent whose polishing rate for the tungsten film 16 is higher than the polishing rate for the titanium film 14 include polishing agents containing alumina as abrasive particles and iron nitrate as an oxidizing agent. When performing the first polishing step using such an abrasive, the tungsten film 1
The polishing rate for the titanium nitride film 15 is substantially equal to the polishing rate for the titanium nitride film 15, but the polishing rate for the titanium film 14 is about one-fifth of the polishing rate for the tungsten film 16. It is easy to end with the remaining. Note that the polishing rate referred to here is a rate when polishing a film deposited on the entire surface of a semiconductor substrate on which no pattern is formed.

From such a viewpoint, the polishing rate for the lower conductive film such as the titanium film 14 is reduced by the tungsten film 1.
It is preferable that the polishing rate is smaller than the polishing rate for the upper conductive film such as 6. In this case, it is more preferable to select the material of the upper conductive film and the lower conductive film or to select the abrasive so that the polishing rate ratio is about half or less.

As described above, below the upper conductive film,
In the case where a base film having a stacked structure including the intermediate conductive film and the lower conductive film is deposited, the polishing rate for the lower conductive film may be lower than the polishing rate for the upper conductive film.

As described above, at the end of the first polishing step, the oxide film 12 may be slightly exposed, but from the viewpoint of avoiding oxide film erosion, it is preferable that the oxide film 12 is not exposed at all. . However, in practice, when the tungsten film 16 other than the plug holes, that is, the tungsten film 16 deposited on the oxide film 12 is to be completely removed due to the non-uniformity of the polishing rate in the substrate surface, the polishing on the substrate is required. Oxide film 12 may be exposed due to a variation in pressure or a variation in thickness of the conductive film. According to the above-mentioned polishing agent, the polishing rate for the titanium film 14 is about one fifth of the polishing rate for the tungsten film 16 and the titanium nitride film 15, so that the polishing rate is maintained to a certain degree in the substrate surface. If done, oxide film 1
It is possible to end the first polishing step in a state where 2 is not exposed.

However, when the polishing rate is not uniform in the substrate surface, the above-mentioned polishing rate selection ratio is not sufficient, and the oxide film 12 may be exposed. Therefore, it is necessary to use an abrasive that hardly polishes the titanium film 14. However, in this case, since the oxide film 12 is not exposed, it is not necessary to consider the polishing rate for the oxide film 12.

By the way, the oxide film erosion corresponds to the oxide film 1.
Since the polishing time after the exposure of the oxide film 12 is substantially proportional to the polishing time, the erosion of the oxide film is reduced if the polishing time after the exposure of the oxide film 12 is short. Therefore, at the end of the first polishing step, the oxide film 12 may be slightly exposed.

The oxidizing agent contained in the polishing agent used in the first polishing step may be potassium iodate or hydrogen peroxide instead of iron nitrate. When potassium iodate or hydrogen peroxide is used as the oxidizing agent, the polishing rate ratio of the polishing rate for the titanium film 14 to the tungsten film 16 is one half of the selection rate for the polishing rate for iron nitrate.
To a degree, the tungsten film 16 and the titanium nitride film 1
It is possible to end the first polishing step in a state where titanium film 14 remains while removing 5.

The abrasive particles contained in the abrasive used in the first polishing step may be silica instead of alumina.

The end of the first polishing step may be controlled by controlling the polishing time. However, since the polishing rate for the titanium film 14 is low, the change in the rotation torque of the platen and the change in the surface temperature of the polishing pad are caused. Alternatively, it is preferable to use a change in the vibration of the carrier holding the semiconductor substrate 11 or the like for the end point detection. By doing so, the first polishing step can be surely completed in a state where the titanium film 14 remains.

(Second Polishing Step) Next, a second polishing agent is applied to the titanium film 14 using a polishing agent whose polishing rate for the titanium film 14 is equal to or higher than that for the oxide film 12. By performing a polishing process, as shown in FIG. 1C, a plug 17 made of a tungsten film 16 is formed and the oxide film 12 is completely exposed.

In this case, if the polishing rate for the titanium film 14 is smaller than the polishing rate for the oxide film 12, for example, if the polishing rate for the titanium film 14 is less than about 0.5 times the polishing rate for the oxide film 12, It is not preferable because the thickness variation of the oxide film is larger than the thickness variation of the titanium film 14 remaining on the oxide film 12.

The polishing rate for the titanium film 14 is as follows:
As described above, the polishing rate for the oxide film 12 is equal to or higher than the polishing rate. However, when the polishing rate for the titanium film 14 is considerably higher than the polishing rate for the oxide film 12,
After the oxide film 12 is exposed, polishing of the titanium film 14 deposited on the side surface of the plug 17 made of tungsten progresses more and more, so that oxide film erosion occurs.
Therefore, to prevent oxide film erosion from increasing,
It is preferable to select a polishing rate ratio between the polishing rate for the titanium film 14 and the polishing rate for the oxide film 12.

Polishing rate for titanium film 14 and oxide film 1
As an abrasive having a polishing rate comparable to that of No. 2,
Abrasives containing silica as abrasive particles and ammonium hydroxide as a pH adjuster may be mentioned.

Incidentally, as the abrasive particles contained in the abrasive used in the second polishing step, cerium can be used instead of silica, and as the pH adjuster, potassium hydroxide or the like can be used instead of ammonium hydroxide. Can be used. Further, as the abrasive used in the second polishing step, a neutral abrasive, an abrasive containing an organic alkali, or the like can be used.

In the second polishing step, the oxide film 1
Titanium film 15 and titanium film 14 remaining on
Since the film thickness is small, attention to be paid to the detection of the polishing end point may be reduced, and therefore, the polishing can be completed by time control. Of course, the end point may be detected from a change in the rotation torque of the surface plate.

In the first polishing step and the second polishing step, polishing of the titanium nitride film 15 is not particularly described. However, the polishing agent used in the first polishing step is a titanium nitride film. The polishing rate for the tungsten film 16 and the polishing rate for the tungsten film 16 are substantially equal, and the polishing agent used in the second polishing step has the same polishing rate for the titanium nitride film 15 and the polishing rate for the titanium film 14. It doesn't matter.

By the way, in order to use the oxide film as a polishing stopper, the polishing rate for the oxide film should be
Tungsten film 16 and titanium nitride film 1 are taken into consideration in that oxide film erosion occurs when a titanium nitride film and a polishing agent having a polishing rate smaller than the polishing rate for the titanium film are used.
5, a method of forming plugs or wirings by only one polishing step using a polishing agent having substantially the same polishing rate for the titanium film 14 and the oxide film 12 is also considered. An adverse effect occurs.

As a first problem, since the polishing rate for the titanium film 14 and the polishing rate for the oxide film 12 are almost equal, it is difficult to detect the end point of the polishing, so that the oxide film 12 may be polished largely.

As a second problem, when the polishing rate is not uniform in the plane of the semiconductor substrate 11 due to the variation in the pressing force for pressing the semiconductor substrate 11 against the polishing pad, the oxide film is formed in the portion where the polishing rate is high. Since the oxide film 12 is greatly polished, the variation in the thickness of the oxide film 12 increases. Non-uniformity NU (Non Uni)
format) is expressed by the following equation using the maximum polishing rate Max, the minimum polishing rate Min, and the average polishing rate Ave. NU = (Max−Min) / (2 × Ave) In the following, a tungsten film having a thickness of 600 nm is used as a plug material, a titanium nitride film having a thickness of 100 nm and a titanium film having a thickness of 30 nm are used as a base material, and insulating is performed. The relationship between the thickness of the conductive film (tungsten, titanium nitride, and titanium) and the polishing time when an oxide film is used as the film will be described with reference to FIGS. 2 to 4 show a conventional example, and FIGS. 5 and 6 show an embodiment of the present invention. In FIGS. 2 to 6, the region where the thickness of the conductive film is negative indicates the polishing thickness of the oxide film 12.

FIG. 2 shows the relationship between the film thickness of the conductive film and the polishing time when the polishing rate for the oxide film 12 is equal to the polishing rate for the conductive film. The average polishing rate Ave for the titanium film 15, the titanium film 14, and the oxide film 12 is all 30
0 nm / min, polishing rate nonuniformity NU within the substrate surface is ±
The relationship between the thickness of the conductive film, which is 15%, and the polishing time is shown. In this case, the maximum polishing rate Max is 330 nm /
min, the minimum polishing rate Min is 270 nm / min. When polishing is performed under these conditions, since the polishing rate for the oxide film 12 is equal to the polishing rate for the conductive film, the polishing end point (that is, the timing at which the conductive film deposited on the oxide film 12 is removed) is determined. Since the detection is not reliable, excess polishing is further performed for about 20 seconds after the oxide film 12 is exposed at the position of Min. As shown in FIG. 2, after the oxide film 12 is exposed
If the excess polishing is performed for 0 seconds, the difference in the thickness of the oxide film 12 between the position of Max and the position of Min becomes as large as about 300 nm. In addition, the thickness of the polished oxide film 12 is very large at about 400 nm at the position of Max.

FIGS. 3 and 4 show the relationship between the thickness of the conductive film and the polishing time when polishing is performed until the oxide film 12 is completely exposed. FIG. FIG. 4 shows a case where a potassium iodate-based abrasive is used. In the polishing amount range of the oxide film, the position of Max indicates the polishing film thickness of the oxide film in the pattern region (that is, the erosion portion), and the position of Min indicates the polishing film thickness of the oxide film in the non-pattern region. I have.

More specifically, FIG. 3 and FIG.
A polishing agent containing iron nitrate as an oxidizing agent and alumina as polishing particles (in the case of FIG. 3), which is used as a polishing stopper, that is, generally used for polishing the tungsten film 16; And FIG. 4 shows a conventional polishing method of performing polishing until the oxide film 12 is completely exposed using two types of abrasives, one containing potassium iodate and the other containing abrasive as abrasive particles (in the case of FIG. 4). ing. In addition, as other polishing conditions, in both abrasives,
The polishing pressure is 300 g / cm ^{2 The} platen rotation speed is 60 rpm, and a polishing cloth made of nonwoven fabric is used. Under this condition, tungsten deposited on the entire surface on a substrate without a pattern,
Titanium nitride, titanium and oxide film (plasma TEOS film)
Average polishing rates Ave are 660 nm / min and 500 nm / mi in the case of an iron nitrate-based polishing agent, respectively.
n, 80 nm / min and 10 nm / min, in the case of a potassium iodate-based abrasive, 300 nm respectively
/ Min, 350 nm / min, 120 nm / min and 25 nm / min. However, since there is a high possibility that titanium reacts with the underlying oxide film to form a titanium oxide film, the actual polishing rate for the titanium film 14 is further reduced to 1/2 of the above-mentioned value. In addition, the polishing rate nonuniformity NU within the substrate surface is set to ± 15%. Further, since the polishing rate for the titanium film 14 is low in both polishing agents, even if the end point of the polishing is detected, if the polishing is performed for about 30 seconds after the oxide film 14 is exposed at the Min position, the polishing is performed. I do.

3 and 4 that the difference in the thickness of the oxide film 12 between the position of Max and the position of Min also increases with the increase of the excess polishing time. In the case of an abrasive, a thickness difference of about 100 nm occurs, and in the case of a potassium iodate-based abrasive, a thickness difference of about 90 nm occurs. Therefore, although the difference in thickness of the oxide film is not sufficiently small, it is considerably improved as compared with the case where the polishing rate for the conductive film is equal to the polishing rate for the oxide film (shown in FIG. 2). I understand.

On the other hand, as a specific example of the polishing method according to the present embodiment, both of the above abrasives (ie,
In FIG. 1, the polishing rate for the tungsten film 16 is higher than the polishing rate for the titanium film 14, and the polishing rate for the oxide film 12 is lower than the polishing rate for the tungsten film 16.
About 10 seconds after the titanium film 14 is exposed at the point n, the first polishing is finished. Subsequently, the ratio of the polishing rate of the tungsten film 16 to the polishing rate of the oxide film 16 is smaller than that in the first polishing. The second polishing is performed until the oxide film 12 is completely exposed by using a polishing agent having a small polishing rate and a polishing rate for the titanium film 14 equal to or higher than the polishing rate for the oxide film 12. The reason why the first polishing is finished about 10 seconds after the titanium film 14 is exposed is that the detection of the polishing end point is slightly delayed. The abrasive used in the second polishing contains, for example, ammonium hydroxide or potassium hydroxide as a pH adjuster, for example, silica as abrasive particles, and using this abrasive and the conditions used in the first polishing, The titanium film 14 and the oxide film 12 (plasma TE
The average polishing rate Ave of the OS film) is 100 nm / mi for both.
n, and since the tungsten film 16 is hardly polished, the above condition is satisfied. The second polishing is performed for about 30 seconds by time control with this polishing agent in a state where the nonuniformity NU of the polishing rate in the substrate surface is ± 15%. However, overpolishing is performed for 10 seconds. The reason for setting the excess polishing time to 10 seconds (30 seconds in the conventional example) is that the polishing rate is as large as 100 nm / min.
This is because the titanium film 14 does not remain if excessive polishing is performed for seconds. In addition, since the second polishing is performed with the above-described abrasive, scars are hardly generated on the surface of the oxide film 12.

FIGS. 5 and 6 show the relationship between the film thickness of the conductive film and the polishing time in the case of one embodiment of the present invention. FIG. 5 shows the use of an iron nitrate-based polishing agent during the first polishing. FIG. 6 shows a case where a potassium iodate-based abrasive is used during the first polishing. In the cases shown in FIGS. 5 and 6, it can be seen that the difference in the thickness of the oxide film between the position of Max and the position of Min is smaller than in the cases of FIGS. Further, it can be seen that the polishing time has been significantly reduced.

Further, comparing FIG. 5 (in the case where the polishing agent at the time of the first polishing is iron nitrate) and FIG. 6 (where the polishing agent at the time of the first polishing is potassium iodate), it can be seen from FIG. Since the polishing rate of the titanium film 14 is smaller, the variation in the film thickness in the titanium film 14 is reduced, and the difference in the thickness of the oxide film between the position of Max and the position of Min is smaller.

Hereinafter, the effect of the method of forming an embedded wiring according to the above-described embodiment in which the first polishing step and the second polishing step as described above are performed will be described.

First, because the pressing force for pressing the semiconductor substrate 11 against the polishing pad varies within the substrate surface or the thickness of the tungsten film 16 varies,
Even when the portion where the titanium film 14 is exposed and the portion where the tungsten film 16 remains are mixed at the time of polishing the tungsten film 16, the polishing rate for the tungsten film 16 is reduced in the first polishing step. Since the polishing is performed using a larger abrasive, the polishing of the exposed titanium film 14 is slow, while the polishing of the remaining tungsten film 16 is faster, so that the remaining tungsten film 16 is quickly removed.

In the second polishing step, the ratio of the polishing rate of tungsten film 16 to the polishing rate of oxide film 12 is smaller than that in the first polishing, and the polishing rate of titanium film 14 is lower than that of oxide film 12. Polishing is performed using an abrasive that is at least as high as the polishing rate, so that the pattern area where many plugs and wirings are formed and the non-pattern area where few plugs and wirings are formed are polished at a polishing rate that is almost the same. Therefore, oxide film erosion hardly occurs.

In the first polishing step, the oxide film 12 may be exposed due to a variation in the pressure applied to the substrate or a variation in the thickness of the conductive film, and the surface of the exposed oxide film 12 may be scratched. There is a risk. However, in the first polishing step, the polishing is completed when the titanium film 14 is exposed. Therefore, the polishing time for the oxide film 12 is extremely short. Also,
In the second polishing step, an abrasive containing, for example, silica or cerium as abrasive particles and an abrasive containing, for example, ammonium hydroxide, potassium hydroxide, or the like is used as a pH adjuster. 12 can be almost completely eliminated in the second polishing step.

In the second polishing step, a polishing agent containing silica or cerium as polishing particles and an ammonium hydroxide, potassium hydroxide or the like as a pH adjuster is used, so that the titanium nitride film 15, the titanium film 14, Oxide film 1
2 is polished at substantially the same polishing rate, but since the tungsten film 16 is hardly polished, the upper portion of the plug 17 made of tungsten protrudes from the surface of the oxide film 12. Therefore, a reduction in contact resistance between the plug 17 and the metal wiring formed on the plug 17 is expected. In the conventional polishing method, the condition for projecting the upper portion of the plug 17 from the surface of the oxide film 12 can be realized only by the difference between the polishing rate for the tungsten film 16 and the polishing rate for the oxide film 12, but According to this embodiment, in addition to the difference between the polishing rate for the tungsten film 16 and the polishing rate for the oxide film 12, the difference between the polishing rate for the tungsten film 16 and the polishing rate for the titanium nitride film 15 and the titanium film 14 is also determined. realizable.

Further, in the second polishing step, an abrasive containing silica or cerium as abrasive particles and an ammonium hydroxide or potassium hydroxide as a pH adjuster is used. There is also an advantage that heavy metals such as alumina particles and iron contained therein are removed from the polished surface in the second polishing step.

Hereinafter, more preferable polishing conditions for the above embodiment will be described.

The polishing agent used in the first polishing step has a polishing rate for the tungsten film 16 higher than that for the titanium film 14 and a polishing rate for the tungsten film 16 higher than the polishing rate for the oxide film 12. More preferred.

In this case, since the pressure applied to the semiconductor substrate 11 and the thickness of the tungsten film 16 vary greatly, the oxide film 12 remains in the first polishing step despite the tungsten film 16 remaining. Even if a certain portion is exposed, the remaining tungsten film 16 is promptly removed. However, the titanium film 14
If the polishing speed is very low, the oxide film 12 will not be exposed in the first polishing step, and in this case, it is not necessary to consider the polishing speed of the oxide film.

As the polishing agent used in the second polishing step, the polishing rate for the titanium film 14 is equal to or higher than the polishing rate for the oxide film 12 and has the ability to polish the tungsten film 16. That is, the polishing rate for the tungsten film 16 is more preferably 0.5 times or more the polishing rate for the oxide film 12.

Thus, even if the tungsten film 16 remains at the time when the first polishing step is completed, the remaining tungsten film 16 is promptly removed in the second polishing step.

However, if the polishing rate for the tungsten film 16 is too large compared to the polishing rate for the oxide film 12, even if the oxide film 12 is exposed so that the conductive film remaining on the oxide film 12 is completely removed. The polishing that is performed may cause excessive polishing of the pattern region to cause oxide film erosion. Therefore, the polishing rate ratio of the tungsten film 16 to the oxide film 12 is preferably smaller than the polishing rate ratio of the tungsten film 16 to the oxide film 12 at the time of the first polishing, and particularly preferably 3 times or less. From the above viewpoint, the polishing rate for the tungsten film 16 is preferably 0.5 times or more and 3 times or less the polishing rate for the oxide film 12.

In the first polishing step, the oxide film 1
It has been described that the tungsten film 16 may slightly remain on the second polishing step 2. However, if the polishing agent used in the second polishing step has almost no polishing ability for the tungsten film 16, the first polishing step is performed. The process needs to be performed until the tungsten film 16 is completely removed.

In the above embodiment, the plug 17 made of tungsten is formed by depositing the tungsten film 16 on the underlying film composed of the lower titanium film 14 and the intermediate titanium nitride film 15. However, the above-described polishing method can be applied to a case where a wiring is formed instead of the plug 17. When wiring is formed on the oxide film 12, in addition to the problem of oxide film erosion, when the width of the wiring groove is large, a dishing phenomenon in which the film thickness of the wiring decreases at the center of the wiring may occur. , Depending on both issues,
Although the cross-sectional area of the wiring may be extremely small, which may cause an increase in wiring resistance and a reduction in reliability, the application of the present invention solves both of the above problems.

In the above embodiment, tungsten is used as the main plug material or the main wiring material.
Instead, aluminum, aluminum alloy, copper, or the like can be used. The aluminum alloy mentioned here is an aluminum-copper alloy, an aluminum-silicon-copper alloy, or the like.

In the above-described embodiment, the materials constituting the intermediate conductive film and the lower conductive film include metal materials such as titanium, tungsten, tantalum and molybdenum, alloys of these metal materials, and alloys of these metal materials. Examples thereof include a conductive material in which silicon is added to a metal material, a nitride compound and a carbide compound of the metal material or the conductive material, and a conductive film formed using each of these materials can be used in a single layer or a stacked layer. However, all of the above materials are
Although the above-mentioned polishing conditions cannot always be realized by the abrasive used in the first polishing step and the second polishing step, in that case, it is necessary to set appropriate abrasives and polishing conditions. .

In the above embodiment, the polishing rate for the lower conductive film is determined by the main material of the plug or wiring (tungsten, aluminum, aluminum alloy, copper, etc.).
Since the lower polishing rate is lower than that of the upper conductive film, the first polishing step can be easily completed in a state where the lower conductive film is exposed and the insulating film is not exposed. The insulating film may be exposed due to extremely large non-uniformity in the inside. In such a case, it is preferable that the thickness of the lower conductive film deposited in a region other than the concave portion such as the through hole or the concave groove is larger than the film thickness of the lower conductive film deposited in the concave portion. This makes it possible to end the first polishing step without exposing the insulating film.

However, when the lower conductive film is a titanium film, the titanium film is usually deposited by a sputtering method. Therefore, if the thickness of the titanium film deposited in a region other than the concave portion is increased, the inside of the concave portion is reduced. Also, since the titanium film is deposited thick, the ratio of the main plug material or the main wiring material occupying in the concave portion is reduced, and the wiring resistance may be increased. Therefore, it is necessary to adopt a method of increasing the thickness of the titanium film deposited in a region other than the concave portion without increasing the thickness of the titanium film deposited in the concave portion.

As a first method, at the time of sputtering, by shortening the distance between the substrate and the target and increasing the sputtering time, it is possible to increase the thickness of the side surface titanium film in the recess without increasing the thickness of the side titanium film. The thickness of the titanium film can be increased. However, since the titanium film may be deposited thickly on the bottom in the concave portion, it is necessary to increase the depth in the case of the groove. Here, the titanium film has been described as an example, but any conductive film other than the titanium film may be used as long as it has a polishing rate similar to that of the titanium film and can be deposited by a sputtering method.

As a second method, after a titanium film is deposited over the entire surface of the insulating film having no concave portion, a resist pattern having an opening at a portion corresponding to the concave portion is formed on the titanium film. And etching the titanium film and the oxide film using the resist pattern as a mask.
By doing so, the titanium film in the recessed region is removed by etching, and the recessed portion of the oxide film is formed.
Next, after removing the resist pattern, a titanium film, an intermediate layer, and an upper conductive film are deposited, and then a first polishing step and a second polishing step are performed under the above conditions. here,
Although a titanium film has been described as an example, other types of films may be used as long as the film has a polishing rate similar to that of the titanium film, and the film deposited on the insulating film before the resist is deposited is removed from the inside of the concave portion. Therefore, an electric current does not need to flow, and therefore, an insulating film may be used.

[0083]

According to the method for forming a buried interconnect according to the present invention, even if the pressure applied to the substrate or the thickness of the upper conductive film varies, the exposed lower conductive film can be formed in the first polishing step. While the polishing rate for the remaining upper conductive film is increased while the polishing rate for the
Since the remaining upper conductive film is promptly removed, variation in the total thickness of the upper conductive film and the lower conductive film is reduced. Further, in the second polishing step, the plugs and wirings are not polished as much as in the first polishing, and the pattern region where many plugs and wirings are formed and the non-pattern where few plugs and wirings are formed are formed. The regions are polished at approximately the same polishing rate. The dispersion of the total thickness of the conductive film after completion of the first polishing step is small, and in the second polishing step, plugs and wirings are not polished as much as in the first polishing, and the pattern region is not polished. Since the pattern region and the pattern region are polished at substantially the same polishing rate, erosion is less likely to occur in the insulating film, and variation in the thickness of the insulating film over the substrate surface is reduced.

Therefore, according to the method of forming a buried wiring according to the present invention, erosion hardly occurs in the insulating film, and variation in the thickness of the insulating film can be reduced. The capacity does not vary.

In the method for forming a buried interconnect according to the present invention, the first polishing agent has a polishing rate selection ratio at which the polishing rate for the insulating film is one third or less of the polishing rate for the upper conductive film. Therefore, even if a conventional polishing agent is used in the first polishing step, the first polishing step removes the upper conductive film except for the region of the concave portion, while the lower conductive film remains. Since the polishing is performed as described above, variation in the total thickness of the upper conductive film and the lower conductive film can be reduced without causing erosion in the insulating film. Even if the insulating film is slightly exposed at a certain position, the insulating film is hardly polished.

In the method for forming a buried interconnect according to the present invention, the first polishing agent is such that the polishing rate for the lower conductive film is less than half the polishing rate for the upper conductive film. , The first polishing step can be surely completed when the lower conductive film is exposed.

In the method of forming a buried interconnect according to the present invention, if the second abrasive has a polishing ability for the upper conductive film, the upper conductive film remains when the lower conductive film is exposed. However, the upper conductive film remaining in the second polishing step can be removed.

In the method of forming an embedded wiring according to the present invention, the second polishing agent has a polishing rate selected such that the polishing rate for the upper conductive film is three times or less the polishing rate for the insulating film. Therefore, even if polishing is continued after the insulating film is exposed to completely remove the conductive film remaining on the insulating film, polishing on the upper conductive film deposited in the concave portion does not proceed too much, Insulation film erosion hardly occurs.

In the method for forming a buried interconnect according to the present invention, in the first polishing step, polishing is performed until the upper conductive film is completely removed except for the region of the concave portion. Even if it does not have the polishing ability for the conductive film, it is possible to avoid a situation where the upper conductive film remains and the film thickness varies.

The method for forming an embedded wiring according to the present invention comprises:
An intermediate conductive film depositing step of depositing an intermediate conductive film in a region including a concave portion on the lower conductive film between the lower conductive film depositing step and the upper conductive film depositing step;
When the polishing step includes a step of removing the conductive film of the intermediate layer except for the region of the concave portion, the intermediate conductive layer is deposited to prevent the main material constituting the upper conductive film in the concave portion from diffusing. Even when the lower conductive film is exposed, the first polishing step can be completed.

In this case, if the second polishing agent has a polishing rate selection ratio such that the polishing rate for the intermediate conductive film is higher than the polishing rate for the lower conductive film, the first polishing agent may be used.
Even if the film thickness varies in the polishing step,
In this step, the variation in film thickness can be reduced.

In the above case, in the first polishing step, if the polishing is performed until the conductive film of the intermediate layer is completely removed except for the region of the concave portion, the second polishing agent is applied to the conductive film of the intermediate layer. Even if it does not have a polishing ability for the semiconductor device, it is possible to avoid a situation in which the conductive film of the intermediate layer remains and the film thickness varies.

In the method of forming an embedded wiring according to the present invention, the lower conductive film is a titanium film, the upper conductive film is a tungsten film, and the first abrasive contains alumina as abrasive particles and the oxidizer as an oxidizer. When iron nitrate or potassium iodate is contained, in the first polishing step, polishing can be reliably performed such that the polishing rate for the lower conductive film is lower than the polishing rate for the upper conductive film.

In the method of forming a buried wiring according to the present invention, the insulating film is a silicon oxide film and the underlying conductive film is a titanium film, and the second abrasive in the second polishing step uses silica as abrasive particles. When containing ammonium hydroxide or potassium hydroxide as a pH adjuster,
In the second polishing step, polishing can be reliably performed such that the polishing rate for the insulating film and the polishing rate for the underlying conductive film are substantially equal.

[Brief description of the drawings]

FIGS. 1A to 1C are cross-sectional views showing steps of a method for forming an embedded wiring according to an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the thickness of a conductive film and the polishing time when the polishing rate for an oxide film and the polishing rate for a conductive film are equal (conventional example).

FIG. 3 is a diagram showing the relationship between the thickness of a conductive film and the polishing time when polishing is performed using an iron nitrate-based polishing agent until an oxide film is completely exposed (conventional example).

FIG. 4 is a diagram showing the relationship between the thickness of a conductive film and the polishing time when polishing is performed using a potassium iodate-based abrasive until an oxide film is completely exposed (conventional example).

FIG. 5 is a diagram showing a relationship between a conductive film and a polishing time when polishing is performed by a method according to an embodiment of the present invention using an iron nitrate-based polishing agent.

FIG. 6 is a diagram showing a relationship between a conductive film and a polishing time when polishing is performed by a method according to one embodiment of the present invention using a potassium iodate-based abrasive.

FIG. 7 is a characteristic diagram showing a relationship between a position on a semiconductor substrate and a film thickness of an oxide film in a buried plug formed by the method for forming a buried wiring according to the one embodiment.

FIGS. 8A and 8B are cross-sectional views showing steps of a conventional method for forming an embedded wiring.

FIG. 9 is a characteristic diagram showing the relationship between the position of a semiconductor substrate and the thickness of an oxide film when polished using a polishing agent containing potassium iodate in a conventional method for forming an embedded wiring.

FIG. 10 is a characteristic diagram showing the relationship between the position of a semiconductor substrate and the thickness of an oxide film when polished using a polishing agent containing iron nitrate in a conventional method for forming an embedded wiring.

[Explanation of symbols]

 Reference Signs List 11 semiconductor substrate 12 oxide film 13 through hole 14 titanium film 15 titanium nitride film 16 tungsten film 17 plug

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H01L 21/768 H01L 21/90 A (56) References JP-A-10-74764 (JP, A) JP-A-8-288391 ( JP, A) JP-A-58-4972 (JP, A) JP-A-7-307385 (JP, A) JP-A-8-83780 (JP, A) US Patent 5,380,546 (US, A) (58) Field (Int.Cl. ⁷ , DB name) H01L 21/3205 H01L 21/321 H01L 21/3213 H01L 21/768 H01L 21/28-21/288 H01L 21/44-21/445 H01L 29/40-29 / 51 H01L 29/872 H01L 21/304

Claims (11)

(57) [Claims] An insulating film depositing step of depositing an insulating film on a substrate; a recess forming step of forming a recess in a region of the insulating film where a plug or a wiring is to be formed; Metal material in the area including
Of silicon nitride or carbide compound or metal material
From nitrided or carbonized compounds of conductive materials to which
A lower conductive film depositing step of depositing the underlying conductive film to be the upper conductive film depositing step of depositing the upper conductive film made of a main material of the plugs or the wiring in a region including the concave portion in over the lower conductive film Using the first polishing agent having a polishing rate selectivity for the upper conductive film, wherein the polishing rate for the lower conductive film is smaller than the polishing rate for the upper conductive film, A first polishing step of performing a chemical mechanical polishing so that the lower conductive film is exposed while excluding the region of the concave portion, and the lower conductive film is exposed to the exposed lower conductive film. The lower conductive film is completely removed except for the region of the concave portion by using a second polishing agent having a polishing rate of about the same as or higher than the polishing rate of the insulating film. Will remain The in performing chemical mechanical polishing 2
And a polishing step. 2. An insulating film deposition method for depositing an insulating film on a substrate.
In the region where the plug or the wiring is formed in the insulating film.
A recess forming step of forming a recess, and introducing a lower layer to a region including the recess on the insulating film.
A lower conductive film depositing step of depositing a conductive film, and a step of depositing a region including the concave portion on the lower conductive film.
Deposit an upper conductive film consisting of the main material of the lag or wiring
An upper conductive film deposition step, wherein the upper conductive film is formed on the lower conductive film.
The polishing rate is lower than the polishing rate for the upper conductive film.
Using the first polishing agent having a polishing rate selection ratio,
The upper conductive film is removed except for the region of the concave portion.
Chemical mechanical polishing is performed so that the lower conductive film is exposed.
A first polishing step, wherein the lower conductive film is formed on the lower conductive film.
Polishing rate is about the same as polishing rate for the insulating film
By using the above second abrasive, the lower conductive film is
The insulation while being completely removed except in the area of the recess
Second polishing machine that performs chemical mechanical polishing so that the film remains
Forming a buried interconnect characterized by having a process
The method, wherein the first abrasive has a polishing rate selection ratio such that a polishing rate for the insulating film is one third or less of a polishing rate for the upper conductive film. And buried
Method of forming embedded wiring. 3. The polishing agent according to claim 1, wherein the first polishing agent has a polishing rate selection ratio at which the polishing rate for the lower conductive film is not more than half the polishing rate for the upper conductive film. The method for forming a buried interconnect according to claim 1. 4. The method according to claim 1, wherein the second abrasive has an ability to polish the upper conductive film. Wherein said second abrasive claims, characterized in that the polishing rate for said upper conductive film has a polishing rate selectivity is 3 times or less of the polishing rate of the insulating film 2. The method for forming an embedded wiring according to item 1 . 6. The embedded wiring according to claim 1, wherein in the first polishing step, chemical mechanical polishing is performed until the upper conductive film is completely removed except for a region of the concave portion. Formation method. 7. An insulating film deposition method for depositing an insulating film on a substrate.
In the region where the plug or the wiring is formed in the insulating film.
A recess forming step of forming a recess, and introducing a lower layer to a region including the recess on the insulating film.
A lower conductive film depositing step of depositing a conductive film, and a step of depositing a region including the concave portion on the lower conductive film.
Deposit an upper conductive film consisting of the main material of the lag or wiring
An upper conductive film deposition step, wherein the upper conductive film is formed on the lower conductive film.
The polishing rate is lower than the polishing rate for the upper conductive film.
Using the first polishing agent having a polishing rate selection ratio,
The upper conductive film is removed except for the region of the concave portion.
Chemical mechanical polishing is performed so that the lower conductive film is exposed.
A first polishing step, wherein the lower conductive film is formed on the lower conductive film.
Polishing rate is about the same as polishing rate for the insulating film
By using the above second abrasive, the lower conductive film is
The insulation while being completely removed except in the area of the recess
Second polishing machine that performs chemical mechanical polishing so that the film remains
Forming a buried interconnect characterized by having a process
And depositing an intermediate conductive film in a region including the recess on the lower conductive film between the lower conductive film depositing step and the upper conductive film depositing step. step and further wherein the first polishing step, implantation characterized in that it comprises a step of the conductive film of the intermediate layer is removed except for a region of the recess
Method of forming embedded wiring. 8. The polishing agent according to claim 1, wherein the second polishing agent has a polishing rate selection ratio in which the polishing rate of the intermediate layer against the conductive film is higher than that of the lower conductive film. 8. The method for forming a buried interconnect according to 7. 9. The burying method according to claim 7, wherein in the first polishing step, chemical mechanical polishing is performed until the conductive film of the intermediate layer is completely removed except for the region of the concave portion. Method of forming wiring. 10. An insulating film deposition for depositing an insulating film on a substrate.
A step, in the region where the plug or the wiring is formed in the insulating film
A recess forming step of forming a recess, and introducing a lower layer to a region including the recess on the insulating film.
A lower conductive film depositing step of depositing a conductive film, and a step of depositing a region including the concave portion on the lower conductive film.
Deposit an upper conductive film consisting of the main material of the lag or wiring
An upper conductive film deposition step, wherein the upper conductive film is formed on the lower conductive film.
The polishing rate is lower than the polishing rate for the upper conductive film.
Using the first polishing agent having a polishing rate selection ratio,
The upper conductive film is removed except for the region of the concave portion.
Chemical mechanical polishing is performed so that the lower conductive film is exposed.
A first polishing step, wherein the lower conductive film is formed on the lower conductive film.
Polishing rate is about the same as polishing rate for the insulating film
By using the above second abrasive, the lower conductive film is
The insulation while being completely removed except in the area of the recess
Second polishing machine that performs chemical mechanical polishing so that the film remains
Forming a buried interconnect characterized by having a process
The method, wherein the lower conductive film is a titanium film and the upper conductive film is a tungsten film, wherein the first abrasive includes alumina or silica as abrasive particles and iron oxide or iron nitrate as an oxidizing agent. A method for forming an embedded wiring, comprising potassium iodate . 11. An insulating film deposition for depositing an insulating film on a substrate.
A step, in the region where the plug or the wiring is formed in the insulating film
A recess forming step of forming a recess, and introducing a lower layer to a region including the recess on the insulating film.
A lower conductive film depositing step of depositing a conductive film, and a step of depositing a region including the concave portion on the lower conductive film.
Deposit an upper conductive film consisting of the main material of the lag or wiring
An upper conductive film deposition step, wherein the upper conductive film is formed on the lower conductive film.
The polishing rate is lower than the polishing rate for the upper conductive film.
Using the first polishing agent having a polishing rate selection ratio,
The upper conductive film is removed except for the region of the concave portion.
Chemical mechanical polishing is performed so that the lower conductive film is exposed.
A first polishing step, wherein the lower conductive film is formed on the lower conductive film.
Polishing rate is about the same as polishing rate for the insulating film
By using the above second abrasive, the lower conductive film is
The insulation while being completely removed except in the area of the recess
Second polishing machine that performs chemical mechanical polishing so that the film remains
Forming a buried interconnect characterized by having a process
The method, wherein the insulating film is a silicon oxide film and the lower conductive film is a titanium film, and the second abrasive contains silica as abrasive particles and ammonium hydroxide or water as a pH adjuster. A method for forming a buried wiring , comprising potassium oxide .