JPH06291199A - Method for flattening interlayer insulating film - Google Patents

Abstract

PURPOSE:To provide a layer insulating film with uniform and excellent flatness so that manufacturing accuracy in wiring pattern can be improved. CONSTITUTION:A wiring 25 is patterned on a wafer 21, and the wiring 25 is coated with a layer insulating film 26. Electromagnetic waves 27 are directed to the wafer 21, and Joule's heat 32 is generated by an eddy current 31 in the wiring 25. Then, only a projected part 26a on the wiring 25 in the layer insulating film 26 becomes fluid by heat, and only the projected part 26a flows into a recessed part through gravitation so that the layer insulating film 26 is flattened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for planarizing an interlayer insulating film in a semiconductor device manufacturing process.

[0002]

2. Description of the Related Art With the recent high integration of LSIs, miniaturization and multilayering of wiring patterns are being promoted.
The purpose of the multi-layering is to increase the degree of freedom of wiring and enable computer-based wiring design in addition to high integration. However, due to the increase in the number of layers, the step difference of the interlayer insulating film becomes large, and the processing accuracy of the wiring pattern formed on the interlayer insulating film tends to deteriorate. This will be described below.

As shown by the line a in FIG. 19, when the resist film thickness changes, the resist line width after development also changes.
The line width of the resist changes with a certain amplitude due to the standing wave effect due to the interference between the exposure light and the reflected light from the underlying material such as the wiring material formed on the interlayer insulating film. This amplitude becomes larger as the reflected light from the base becomes stronger and the controllability of the line width becomes worse.

Therefore, when Al or the like having a high reflectance is an underlayer of the resist, it is necessary to perform an antireflection treatment. As the antireflection film, amorphous Si, TiON, an organic high absorption material or the like is used. It is used. When the antireflection treatment is applied, the line width changes linearly as shown by the line b in FIG. However, even if the antireflection treatment is applied, the bulk effect that the line width of the resist becomes thicker as the film thickness of the resist becomes thicker remains.

Further, as shown in FIG. 20, when there is a step 12 on the underlayer 11, the resist 13 cannot faithfully trace the step 12, and the film of the resist 13 is formed above and below the step 12. There is a difference in thickness. As a result, due to the bulk effect described in FIG. 19, the line width of the resist 13 is different above and below the step 12. And FIG. 20 (a)
As is clear from the comparison in (b), since the difference in the film thickness of the resist 13 above and below the step 12 is larger as the step 12 is larger, the difference in the line width of the resist 13 is also larger as the step 12 is larger.

Further, a wiring material is formed on the interlayer insulating film, and as the wiring material, a material having a high reflectance such as Al is generally used. Therefore, in order to improve the controllability of the line width of the resist, the antireflection treatment is performed as described above. However, if the reflected light from the base becomes weak due to the antireflection treatment, the cross-sectional shape deteriorates that the side walls of the resist are not vertical.

As shown in FIG. 21A, this is because the intensity of the exposure light is weak under the resist 13 due to the absorption of light by the resist 13 itself, and the photoreaction is difficult to proceed. This is because the cross section of 13 is tapered. On the other hand, as shown in FIG.
When the reflected light from the underlayer 11 is strong, the photoreaction easily proceeds even under the resist 13 and the developing speed is high, so that the resist 13 having a rectangular cross section can be obtained. That is, the cross-sectional shape of the resist 13 and antireflection are in a trade-off relationship.

As is clear from the above description, as shown in FIG. 22, when the resist 13 is patterned above and below the step 12 of the base 11 which has been subjected to the antireflection treatment, the line width of the resist 13 below the step 12 is reduced. w ₁ and with a difference between the line width w ₂ of the resist 13 above the step 12 becomes w _1> w ₂ occurs, the cross-sectional shape of the resist 13 is tapered. Therefore, it is important to flatten the interlayer insulating film, and as a method therefor, an etch back method, a reflow method, an SOG coating method, a polishing method and the like have been conventionally considered.

[0009]

However, even if the interlayer insulating film is flattened by any one of the etch back method, the reflow method and the SOG coating method, the variation in the line width of the resist 13 is within an allowable range. An interlayer insulating film having high flatness could not be obtained. In addition, although high flatness can be obtained by the polishing method, the polishing agent does not reach the center of the wafer, and the peripheral speed when the wafer is rotated also differs depending on the radial position. The uniformity was not good.

[0010]

According to a first aspect of the present invention, there is provided a method of planarizing an interlayer insulating film, wherein the convex portion 26a of the interlayer insulating film 26 is heated to fluidize the convex portion 26a. It is characterized in that the insulating film 26 is flattened.

According to a second aspect of the present invention, in the method of flattening the interlayer insulating film 26, the interlayer insulating film 26 is flattened by etching the interlayer insulating film 26 with only the convex portions 26a of the interlayer insulating film 26 being heated. It is characterized by becoming.

According to a third aspect of the present invention, there is provided an interlayer insulating film planarizing method according to the first or second aspect, wherein the interlayer insulating film 26 covers the wiring 25 and the electromagnetic wave 2 is generated.
It is characterized in that the wiring 25 is selectively heated by irradiating the wirings 7 and 36, and only the convex portion 26a on the wiring 25 is heated by this heat.

[0013]

In the flattening method of the interlayer insulating film according to the first aspect, since only the convex portion 26a of the interlayer insulating film 26 is fluidized, only the convex portion 26a flows into the concave portion due to gravity, and the flatness is improved. It is possible to obtain the interlayer insulating film 26 having an extremely high temperature. Moreover, since the phenomenon that the fluidized convex portion 26a flows to the concave portion is caused by gravity, this phenomenon occurs in the wafer 2
It occurs in any area of 1. Therefore, it is possible to obtain the interlayer insulating film 26 having good uniformity in flatness.

According to a second aspect of the present invention, there is provided a method of flattening an interlayer insulating film,
Although the interlayer insulating film 26 is etched in a state where only the convex portion 26a of the interlayer insulating film 26 is heated, the etching speed is increased by heating. Therefore, in the interlayer insulating film 26, the amount of etching of the convex portion 26a is larger than that of the concave portion, and the interlayer insulating film 26 having extremely high flatness can be obtained. In addition, since the phenomenon that the etching rate increases due to heating occurs in any region of the wafer 21, it is possible to obtain the interlayer insulating film 26 having good flatness uniformity.

According to the third aspect of the present invention, there is provided an interlayer insulating film planarizing method,
Since the wiring 25 is selectively heated and the convex portion 26a on the wiring 25 of the interlayer insulating film 26 is heated, only the convex portion 26a of the interlayer insulating film 26 can be easily heated. .

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The first to ninth embodiments of the present invention will be described below with reference to FIGS. FIG. 3 shows an apparatus for carrying out the first embodiment. In this apparatus, an electromagnetic wave irradiation device 23 is arranged above and below a wafer holding table 22 for holding the wafer 21, and
A wafer transfer device 24 is arranged on the side of.

In the first embodiment using such an apparatus, as shown in FIG. 1, an Al film having a thickness of 600 nm is patterned on the wafer 21 to form wiring 25, and an S film having a thickness of 1 μm is formed.
The wiring 25 and the wafer 21 are formed by the interlayer insulating film 26 which is an OG film.
Cover the surface of. Then, as shown in FIG. 4A, the wafer 21 is transferred by the wafer transfer device 24 and placed on the wafer holding table 22.

Next, as shown in FIGS. 1 and 4B, the electromagnetic wave irradiation device 23 irradiates the wafer 21 with the electromagnetic wave 27 having a frequency of 100 MHz at 150 W for 10 minutes. Due to this irradiation, an eddy current 31 is generated in the wiring 25, and further the Joule heat 32 is selectively generated in the wiring 25 by the eddy current 31. Therefore, the portion of the interlayer insulating film 26 immediately above the wiring 25, that is, only the convex portion 26a of the interlayer insulating film 26 is heated to 300 ° C. or higher.

As a result, the convex portion 2 of the interlayer insulating film 26 is
Only 6a is fluidized, and only this convex portion 26a flows to the concave portion due to gravity, so that the interlayer insulating film 26 is flattened. After that, as shown in FIG. 4C, the wafer 21 is taken out from the wafer holder 22 by the wafer transfer device 24. In the first embodiment described above, since the wiring 25 has a thickness of 600 nm, there was a step difference of 600 nm in the interlayer insulating film 26 immediately after the formation of the interlayer insulating film 26. Reduced to.

FIG. 5 shows an apparatus for carrying out the second embodiment. This apparatus is shown in FIG. 3 except that the wafer holder 22 is arranged in the etching tank 33 and the etching solution 34 for the interlayer insulating film 26, for example, hydrofluoric acid is filled in the etching tank 33. It has substantially the same configuration as the device for executing the first embodiment.

In the second embodiment using such a device, as shown in FIG. 6 (a), the wafer 21 having the interlayer insulating film 26 formed thereon is transferred to the wafer transfer device 24 as in the first embodiment. Then, the wafer is conveyed by and placed on the wafer holder 22 in the etching tank 33. Then, as shown in FIG. 6B, a frequency of 100 MHz is generated by the electromagnetic wave irradiation device 23.
The wafer 21 is irradiated with the electromagnetic wave 27 of 50 W for 1 minute, and at the same time, the interlayer insulating film 26 is etched by the etching liquid 34.

By the irradiation of the electromagnetic wave 27, Joule heat 32 is selectively generated in the wiring 25, and only the convex portion 26a of the interlayer insulating film 26 is heated, and the etching rate of the convex portion 26a is increased. As a result, the etching amount of the convex portion 26a in the interlayer insulating film 26 is larger than that of the concave portion,
The interlayer insulating film 26 is flattened. After that, as shown in FIG. 6C, the wafer 21 is taken out from the wafer holder 22 by the wafer transfer device 24. In the second embodiment as described above, the step difference of 600 nm immediately after the formation of the interlayer insulating film 26 was reduced to 50 nm by the flattening.

FIG. 7 shows an apparatus for carrying out the third embodiment. This device has substantially the same configuration as the device for carrying out the second embodiment shown in FIG. 5, except that an excimer laser device 35 is arranged instead of the electromagnetic wave irradiation device 23. ing.

In the third embodiment using such an apparatus, as shown in FIG. 8A, as in the case of the second embodiment, the wafer 21 having the interlayer insulating film 26 formed is etched into the etching bath 3
The wafer 3 is placed on the wafer holder 22. And in FIG.
As shown in FIG. 8B, the excimer laser device 35 irradiates the wafer 21 with far ultraviolet rays 36 of 500 mJcm ^{−2 at} a wavelength of 248 nm for 1 minute, and at the same time, etches the interlayer insulating film 26 with the etching liquid 34. .

As to the electromagnetic wave having a short wavelength such as the far ultraviolet ray 36, as shown in FIG. 2, the convex portion 26a functions as a lens and focuses the far ultraviolet ray 36 on the wiring 25. Heated selectively. Therefore, the interlayer insulating film 26
Of these, only the protrusion 26a is heated, and the protrusion 26a
The etching rate of becomes faster.

As a result, the amount of etching of the convex portion 26a of the interlayer insulating film 26 is larger than that of the concave portion, and the interlayer insulating film 26 is planarized. Thereafter, as shown in FIG. 8C, the wafer 21 is taken out from the wafer holder 22 by the wafer transfer device 24. In the third embodiment as described above, the step difference of 600 nm immediately after the formation of the interlayer insulating film 26 is
It was reduced to 50 nm by flattening.

FIG. 9 shows an apparatus for carrying out the fourth embodiment. This device has no etching bath 33,
A quartz plate 37 is arranged between the excimer laser device 35 and the wafer holder 22, and the third embodiment shown in FIG. 7 is executed except that the quartz plate 37 is moved up and down by a driving device 38. It has substantially the same configuration as the device for performing.

In the fourth embodiment using such an apparatus, as shown in FIG. 10A, as in the case of the first embodiment, the wafer 21 on which the interlayer insulating film 26 is formed is placed on the wafer holder 22. Place on top. Then, as shown in FIG.
With the excimer laser device 35, the wavelength of 248 nm is 5
The wafer 21 is irradiated with deep ultraviolet rays 36 of 00 mJcm ⁻² at 150 W for 10 minutes. The far ultraviolet rays 36 pass through the quartz plate 37.

As a result, as shown in FIG. 2, the convex portion 26a is formed.
Functions as a lens and focuses the far ultraviolet rays 36 on the wiring 25, so that the wiring 25 is selectively heated. Therefore, the portion of the interlayer insulating film 26 immediately above the wiring 25, that is, only the convex portion 26a of the interlayer insulating film 26 is 300 ° C.
When heated above, only the convex portion 26a is fluidized.

Next, as shown in FIG. 10C, the quartz plate 37 is lowered by the driving device 38, and the quartz plate 37 is moved.
Are pressed against the wafer 21. At this time, since only the convex portion 26a of the interlayer insulating film 26 has already fluidized, only the convex portion 26a is pushed by the quartz plate 37 and flows into the concave portion,
The interlayer insulating film 26 is flattened.

Thereafter, as shown in FIG. 10D, the quartz plate 37 is raised by the driving device 38 and the wafer 21 is taken out from the wafer holding table 22 by the wafer transfer device 24. In the fourth embodiment as described above, the interlayer insulating film 2
The 600 nm step immediately after the formation of 6 was reduced to 50 nm by the flattening.

FIG. 11 shows an apparatus for carrying out the fifth embodiment. In this apparatus, a pin 41 for moving the wafer 21 up and down is built in a wafer holder 42, and a flat heating plate 43 held by a driving device 38 is arranged above the wafer holder 42. Heating plate 43
A heater 44 and a thermometer 45 are built in the heater, and the temperature controller 46 keeps the heating plate 43 at a desired temperature. Further, the wafer transfer device 2 is provided on the side of the wafer holder 42.
4 are arranged.

In the fifth embodiment using such an apparatus, as shown in FIG. 12 (a), the wafer 21 having the interlayer insulating film 26 formed thereon is transferred to the wafer transfer device 24 as in the first embodiment. Then, the wafer is carried by and placed on the pins 41 protruding from the wafer holder 42. And FIG.
As shown in (b), the pins 41 are lowered to move the wafer 21.
Are fixed to the wafer holder 42.

Next, as shown in FIG. 12C, 400 ° C.
The heating plate 43 controlled to the temperature is lowered by the driving device 38 and pressed against the wafer 21. As a result, a portion of the interlayer insulating film 26 that is in contact with the heating plate 43 is fluidized, the flatness of the heating plate 43 is transferred to the interlayer insulating film 26, and the interlayer insulating film 26 is planarized.

Next, as shown in FIG. 12D, the heating plate 43 is raised by the drive unit 38 to separate it from the wafer 21, and at the same time, the pins 41 are raised to lift the wafer 21 from the wafer holding table 42. . After that, the wafer transfer device 2
The wafer 21 is taken out from the wafer holding table 42 by 4. In the fifth embodiment as described above, the level difference of 600 nm immediately after the formation of the interlayer insulating film 26 is reduced to 10 by flattening.
It was reduced to 0 nm.

FIG. 13 shows an apparatus for carrying out the sixth embodiment. In this device, a roller 47 is used instead of the heating plate 43, and the driving device 38 uses the roller 47.
11 has a configuration substantially similar to that of the apparatus for carrying out the fifth embodiment shown in FIG. 11, except that the roller 47 is not only moved up and down but also the roller 47 is rolled parallel to the surface of the wafer holding table 42. is doing.

Also in the sixth embodiment using such an apparatus, as shown in FIGS. 14A and 14B, the wafer 21 is fixed to the wafer holding table 42 in the same manner as in the fifth embodiment. Then, as shown in FIG. 14C, the roller 47, which is controlled at a temperature of 400 ° C., is lowered by the drive unit 38 to lower the wafer 2
Then, the roller 47 is rolled on the wafer 21. As a result, among the interlayer insulating film 26, the roller 4
The portion in contact with 7 is fluidized to flatten the interlayer insulating film 26, and the air sandwiched between the step of the interlayer insulating film 26 and the roller 47 is pushed out by the rolling of the roller 47.

Next, as shown in FIG. 14D, the driving device 38 raises the roller 47 to separate it from the wafer 21, and at the same time, raises the pin 41 to raise the wafer 21 from the wafer holding table 42. After that, the wafer transfer device 2
The wafer 21 is taken out from the wafer holding table 42 by 4. In the sixth embodiment as described above, the level difference of 600 nm immediately after the formation of the interlayer insulating film 26 is reduced to 50 by the planarization.
down to nm.

FIG. 15 shows an apparatus for carrying out the seventh embodiment. In this device, a flat plate 51 is used instead of the heating plate 43, and a heater 44 and a thermometer 45 are used.
Has a structure substantially similar to that of the apparatus for carrying out the fifth embodiment shown in FIG.

In the seventh embodiment using such an apparatus, the wafer holding table 42 is controlled at a temperature of 400 ° C., and in the case of the fifth embodiment, as shown in FIGS. The wafer 21 is fixed to the wafer holder 42 in the same manner as. Therefore, the temperature of the wafer 21 also becomes 400 ° C., and the interlayer insulating film 26 is fluidized. After that, as shown in FIG.
The flat plate 51 is lowered by the driving device 38 and pressed against the wafer 21. At this time, since the interlayer insulating film 26 is already fluidized, the flatness of the flat plate 51 is transferred to the interlayer insulating film 26 and the interlayer insulating film 26 is flattened.

Next, as shown in FIG. 16D, the flat plate 51 is raised by the driving device 38 to separate it from the wafer 21, and at the same time, the pins 41 are raised to lift the wafer 21 from the wafer holding table 42. . After that, the wafer transfer device 2
The wafer 21 is taken out from the wafer holding table 42 by 4. In the seventh embodiment as described above, the level difference of 600 nm immediately after the formation of the interlayer insulating film 26 is reduced to 10 by flattening.
It was reduced to 0 nm.

Next, an eighth embodiment will be described. The fifth mentioned above
In the seventh embodiment, only one of the heating plate 43 or the roller 47 and the wafer holding table 42 is heated to a temperature of 400 ° C., but in the eighth embodiment, the heating plate 43 or the roller 47 is used. Substantially the same steps are performed as in the fifth to seventh embodiments described above, except that both the wafer holder 42 and the wafer holder 42 are heated to a temperature of 400 ° C. In the eighth embodiment, the step difference of 600 nm immediately after the formation of the interlayer insulating film 26 was reduced to 50 nm by the flattening.

FIG. 17 shows an apparatus for carrying out the ninth embodiment. In this apparatus, a wafer holder 42 and a heating plate 43 are arranged in a chamber 52, and the inside of the chamber 52 is closed by a rotary pump 54 in a state of being sealed by a shutter 53 provided at an inlet of the chamber 52. It has substantially the same configuration as the apparatus for carrying out the fifth embodiment shown in FIG. 11 except that the pressure is reduced to × 10 ⁴ Pa (about 0.1 atm).

In the ninth embodiment using such a device, as shown in FIG. 18A, with the shutter 53 open,
The wafer 21 is placed on the pins 41 in the same manner as in the fifth embodiment. Then, as shown in FIG. 18B, the shutter 53 is closed to seal the chamber 52, and the pressure inside the chamber 52 is reduced to 1 × 10 ⁴ Pa by the rotary pump 54. Then, the pins 41 are lowered to fix the wafer 21 to the wafer holding table 42.

Next, as shown in FIG. 18C, the heating plate 43 is pressed against the wafer 21 to flatten the interlayer insulating film 26 in the same manner as in the fifth embodiment. At this time, since air hardly exists in the region sandwiched between the step of the interlayer insulating film 26 and the heating plate 43, the flatness of the interlayer insulating film 26 becomes higher than that in the fifth embodiment.

Next, as shown in FIG. 12D, the heating plate 43 is separated from the wafer 21 and the wafer 21 is lifted from the wafer holder 42 at the same time as in the case of the fifth embodiment. To return the inside of the chamber 52 to atmospheric pressure. After that, the wafer 21 is taken out from the wafer holder 42 by the wafer transfer device 24. 9th as above
In the example, 600 immediately after the formation of the interlayer insulating film 26
The level difference of nm was reduced to 10 nm by the flattening.

[0047]

According to the flattening method of the interlayer insulating film of the first and second aspects, since the interlayer insulating film having extremely high flatness and good uniformity of flatness can be obtained, the wiring material on the interlayer insulating film is obtained. The film thickness of the resist applied on top is uniform, and the processing accuracy of the wiring pattern can be improved.

In the flattening method of the interlayer insulating film according to claim 3,
Since only the convex portion of the interlayer insulating film can be easily heated, the flattening method of the interlayer insulating film according to claim 1 or 2 can be easily performed.

[Brief description of drawings]

FIG. 1 is a side sectional view for explaining a first principle of heating in the invention of the present application.

FIG. 2 is a side sectional view for explaining the second principle of heating in the invention of the present application.

FIG. 3 is a side view of an apparatus for carrying out the first embodiment of the invention of the present application.

FIG. 4 is a side view showing the first embodiment in order of steps.

FIG. 5 is a side view of an apparatus for performing the second embodiment.

FIG. 6 is a side view showing the second embodiment in the order of steps.

FIG. 7 is a side view of an apparatus for performing the third embodiment.

FIG. 8 is a side view showing the third embodiment in the order of steps.

FIG. 9 is a side view of an apparatus for performing the fourth embodiment.

FIG. 10 is a side view showing the fourth embodiment in the order of steps.

FIG. 11 is a side view of an apparatus for performing the fifth embodiment.

FIG. 12 is a side view showing the fifth embodiment in the order of steps.

FIG. 13 is a side view of an apparatus for performing the sixth embodiment.

FIG. 14 is a side view showing the sixth embodiment in the order of steps.

FIG. 15 is a side view of an apparatus for performing the seventh embodiment.

FIG. 16 is a side view showing the seventh embodiment in the order of steps.

FIG. 17 is a side view of an apparatus for performing the ninth embodiment.

FIG. 18 is a side view showing the ninth embodiment in the order of steps.

FIG. 19 is a graph showing the relationship between resist film thickness and line width.

FIG. 20 is a side sectional view showing the film thickness of a resist above and below a step.

FIG. 21 is a side sectional view showing the relationship between the intensity of light reflected from the base and the sectional shape of the resist.

FIG. 22 is a side sectional view showing resist line widths above and below a step.

[Explanation of symbols]

 25 wiring 26 interlayer insulating film 26a convex portion 27 electromagnetic wave 36 far ultraviolet ray

Claims (3)

[Claims] 1. A method of planarizing an interlayer insulating film, which comprises flattening the interlayer insulating film by heating only a convex part of the interlayer insulating film to fluidize the convex part. 2. The interlayer insulating film is etched by heating only the convex portion of the interlayer insulating film,
A method of planarizing an interlayer insulating film, which comprises planarizing the interlayer insulating film. 3. The wiring is covered with the interlayer insulating film to radiate electromagnetic waves to selectively heat the wiring, and the heat only heats the convex portions on the wiring. Item 3. A method for planarizing an interlayer insulating film according to Item 1 or 2.