KR20060058424A - Plasma chamber system and method of ashing a photoresist pattern formed on the substrate having low-k dielectric using the same - Google Patents

Abstract

A plasma chamber system and a method of ashing a photoresist pattern formed on a substrate having a low dielectric film using the same are provided. The plasma chamber system includes a process chamber, a wafer chuck disposed within the process chamber, a lower radio-frequency power source electrically connected to the wafer chuck, an upper electrode disposed above the wafer chuck, and an upper helm disposed above the process chamber. A Holtz coil and a lower Helmholtz coil disposed under the process chamber.

Description

Plasma Chamber System And Method Of Ashing A Photoresist Pattern Formed On The Substrate Having Low-k Dielectric Using The Same}

1A and 1B are scanning electron micrographs showing a cross section of an interlayer insulating film before and after an ashing process to explain a problem occurring in the conventional ashing method.

2 is an apparatus configuration diagram for schematically illustrating a plasma chamber system according to the present invention.

3 and 4 are graphs for explaining the effect of the plasma chamber system according to the present invention.

5 is a process flow chart for explaining the method of the present invention for ashing a photoresist pattern formed on a substrate having a low dielectric film.

6 is a cross-sectional view illustrating a process and characteristics of an ashing process according to the present invention.

7A and 7B are scanning electron microscope photographs taken before and after an ashing process, respectively, to illustrate an effect of the ashing process according to the present invention.

The present invention relates to a semiconductor manufacturing apparatus and a method for manufacturing a semiconductor device using the apparatus, and more particularly, to a plasma chamber system and a method for ashing a photoresist pattern formed on a substrate having a low dielectric film using the same.

In order to meet the demand for miniaturization, high integration, and high speed of highly integrated semiconductor devices, researches for forming interlayer insulating films from low dielectric materials have been extensively performed. Since the silicon oxide film (SiO ₂ ), which is widely used as the interlayer insulating film, is so high that the dielectric constant is 3.9 to 4.2, it is not suitable as the interlayer insulating film material for the above-mentioned high speed of semiconductor devices. In particular, according to the Road Map of the International Technology Roadmap for Semiconductor (ITRS), in semiconductor devices with a minimum critical dimension of 0.13 μm and a driving speed of 2100 MHz or more, the material used for wiring is also resisted in current aluminum It is expected that this will turn into low copper (Cu). In this case, the interlayer material of the gold wire should be formed of a material having a dielectric constant of 3.0 or less.

TABLE 1

ITRS Road Map

In particular, as shown in Table 1, low-k materials having a bulk dielectric constant of 2.0 or less are expected to be applied to highly integrated semiconductor devices after 2004. This is because parasitic capacitance that causes RC delay, increased power consumption, and noise caused by mutual interference is not used between wires when low dielectric materials are not used as inter metal dielectric in the development of 0.13 μm or less devices. This is because it increases rapidly. Since the increase in parasitic capacitance is an obstacle to high speed, low power, and high integration of semiconductor devices, research into using a low dielectric material as an interlayer insulating film has been conducted as described above.

However, when the low dielectric material is used as an interlayer insulating film, an ashing process for removing the photoresist pattern becomes difficult. This is because the conventional ashing process adopts the method of using oxygen gas at high temperature, thereby impairing the low dielectric properties of the interlayer insulating film or reducing the mechanical robustness.

In more detail, in order to reduce the dielectric constant of the interlayer insulating film, the forming of the interlayer insulating film uses a technique of adding a process gas such as hydrogen or CH ₃ or forming a pore in the interlayer insulating film. In this case, the conventional ashing process heats the process chamber to a temperature of about 250 ° C. or more through direct heating of the chuck on which the semiconductor substrate is loaded or through a separate heating means such as a halogen lamp, and then the oxygen gas and Supplying an additive gas. In such high temperature process conditions, the oxygen gas is decomposed into oxygen radicals used to remove the photoresist.

However, the oxygen radicals, which move isotropically, penetrate into the interlayer insulating film through the exposed sidewall of the interlayer insulating film (for example, the inner wall of the hole), and combine with hydrogen or CH ₃ or destroy the pore. Compromise dielectric properties or mechanical robustness. Comparing the photograph before the ashing process (see FIG. 1A) and the photograph after the ashing process (see FIG. 1B), it can be seen that the sidewall of the low dielectric interlayer insulating film is seriously damaged after the conventional ashing process. As such, the activity of the oxygen radical is further increased at a high temperature, so the ashing process using the oxygen radical at a high temperature is difficult to be applied to a case having a low dielectric interlayer insulating film.

In order to prevent damage to low dielectric properties of the interlayer insulating film due to oxygen radicals, another ashing process using hydrogen and helium at high temperature conditions has been proposed. Since this method uses the reducing action of hydrogen, it does not change the physical properties of the low dielectric film. However, this method has a disadvantage of low productivity due to a slow ashing speed and a high process temperature.

On the other hand, the technical difficulty of the ashing process using the above-described oxygen radicals occurs because high temperature process conditions are required to activate the oxygen radicals. Therefore, as another alternative to overcome this technical difficulty, it is necessary to develop a plasma chamber system capable of activating the oxygen radical at low temperatures.

However, the commonly used capacitively coupled plasma chamber system is effective in increasing the etch rate by increasing the density of the plasma formed inside the chamber, but does not control the plasma uniformity according to the position. As a result, with the recent increase in the size of the substrate, there is an increasing demand for a plasma chamber system that can compensate for an increase in the plasma density and a nonuniformity of the plasma density according to the position.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a plasma chamber system capable of compensating positional nonuniformity of plasma density as well as increasing plasma density.

Another object of the present invention is to provide a plasma chamber system capable of removing the photoresist formed on the low dielectric film without impairing the properties of the low dielectric film.

Another technical problem to be achieved by the present invention is to provide an ashing method capable of removing the photoresist without damaging the low dielectric film.                         

Another technical object of the present invention is to provide an ashing method capable of removing the photoresist at low temperatures.

In order to achieve the above technical problem, the present invention provides a plasma chamber system having Helmholtz coils that can be independently controlled at the top and bottom of the process chamber. The plasma chamber system includes a process chamber, a wafer chuck disposed within the process chamber, a lower radio-frequency power source electrically connected to the wafer chuck, an upper electrode disposed above the wafer chuck, and an upper helm disposed above the process chamber. A Holtz coil and a lower Helmholtz coil disposed under the process chamber.

According to the embodiments of the present invention, there is further provided an upper power supply for supplying a first current to the upper Helmholtz coil and a lower power supply for supplying a second current to the lower Helmholtz coil. In this case, the first current is a direct current of approximately -10 to 10 amperes (A), and the second current is preferably a direct current of approximately -10 to 10 amps (A).

In addition, a controller is connected to the upper power supply and the lower power supply to adjust the magnitudes of the first current and the second current, thereby correcting the density and uniformity of plasma generated in the process chamber.

In order to achieve the above technical problem, the present invention provides a method of ashing a photoresist pattern capable of activating oxygen radicals at low temperatures. In this method, a low dielectric film is formed on a semiconductor substrate, a photoresist pattern is formed on a semiconductor substrate including the low dielectric film, and the semiconductor substrate including the photoresist pattern is formed on an upper Helmholtz coil, a lower Helmholtz coil, After loading into an ashing chamber having an upper electrode and a lower electrode, removing the photoresist pattern while supplying an ashing gas containing oxygen into the ashing chamber. In this case, the removing of the photoresist pattern may be performed by applying a first DC current and a second DC current to the upper Helmholtz coil and the lower Helmholtz coil, respectively, while maintaining the internal temperature of the ashing chamber at approximately 0 to 80 ° C. It is characterized by applying.

According to embodiments of the present invention, the ashing gas is characterized in that it comprises at least one gas and oxygen gas selected from the group of additive gases consisting of nitrogen gas, inert gas, reducing gas and CF-based gas. For example, the ashing gas is nitrogen (N ₂ ) gas, helium (He) gas, argon (Ar) gas, hydrogen (H ₂ ) gas, helium hydrogen (H ₂ He) gas, nitrogen hydrogen (H ₂ N ₂ ) And at least one gas selected from carbon tetrafluoride (CF ₄ ) and methane trifluoride (CHF ₃ ) and oxygen gas. At this time, the ashing gas is preferably supplied to the ashing chamber at a flow rate of approximately 30 to 3000sccm.

In addition, the first and second currents applied to the upper Helmholtz coil and the lower Helmholtz coil may be independently adjusted to locally control the density of the plasma formed in the ashing chamber. According to the present invention, both the first current and the second current can be adjusted in the range of -10 amps to 10 amps.

In the removing of the photoresist, the lower electrode is preferably applied with power of approximately 100 to 2500 watts, and the internal pressure of the ashing device is maintained at 10 to 600 millitorr (mT).

The low dielectric film is methylsilsesquioxane (MSQ), hydrogen silsesquioxane (HSQ), SiOF, SiOC, a-uorocarbon, SiLK, polyimides, spin-on-glasses, fluorinated polyimides, diamond-like carbon (DLC), Cyclotenes, Parylene N, Poly at least one selected from (arylene ethers), Poly (arylenes), Poly (norbornens), Polyimide-SSQ hybrids, Alkyl-silanes / N ₂ O, Teflon-AF, Teflon microemulsion, Polyimide nanofoams, silica aerogels, silica xerogels, and Mesoporous silica It can be formed of a material.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed subject matter is thorough and complete, and that the spirit of the present invention to those skilled in the art will fully convey. In the drawings, the thicknesses of layers and regions are exaggerated for clarity. If it is also mentioned that the layer is on another layer or substrate it may be formed directly on the other layer or substrate or a third layer may be interposed therebetween.

2 is a device configuration diagram showing a schematic configuration of a plasma chamber system according to the present invention.

Referring to FIG. 2, the plasma chamber system 100 according to the present invention includes a process chamber 130, a supply pipe 170 for supplying process gases to the process chamber 130, and a process pressure inside the process chamber 130. It includes a valve device 140 for adjusting the. The valve device 140 is connected with a vacuum pump 150 for discharging the process gas and its reactants at a constant speed. During the process, the internal pressure of the process chamber 130 is maintained at approximately 10 to 600 millitorr (mT), the temperature is preferably maintained in the range of approximately 0 to 80 ℃. To this end, the vacuum pump 150 is preferably a turbo molecular pump (TMP).

In addition, a chuck 180 on which the substrate 200 is mounted is disposed in the process chamber 130, and a coolant tube 220 to which a coolant is supplied is connected to the chuck 180. The substrate 200 is adjusted to a predetermined temperature during the process by the refrigerant. The chuck 180 serves as a lower electrode for plasma formation. To this end, the chuck 180 is electrically connected to a bottom RF generator 120 disposed outside the process chamber 130. The lower electrode 180 receives power from the lower RF power supply 120 to dissociate the process gas supplied into the process chamber 130 into ions, electrons, and neutral radicals. According to embodiments of the present invention, the lower RF power supply 120 may supply power of approximately 100 to 2500 watts having a frequency of approximately 13.56 MHz.

In the process chamber 130, a barrier wall 160, an upper electrode 210, and a channel 230 for controlling the flow of process gases supplied through the supply pipe 170 are disposed. The partition wall 160 and the upper electrode 210 are disposed to uniformly diffuse the process gas in the process chamber 130, and the channel 230 includes the process gas and reactants thereof in the process chamber. It is arranged to be evenly discharged to the outside of the 130. In this case, the upper electrode 210 may be electrically connected to the upper RF power source 250 disposed outside the process chamber 130.

A gate door 240 for loading or unloading the substrate 200 is disposed on sidewalls of the process chamber 130. The gate door 240 is closed while the process is being performed, thereby maintaining the pressure inside the process chamber 130 in a high vacuum state.

Upper and lower Helmholtz Coils 111 and bottom Helmholtz Coils 112 may be disposed at upper and lower portions of the process chamber 130, respectively. An upper power supply 113 and a lower power supply 114 for supplying a first current and a second current are disposed in the upper and lower Helmholtz coils 111 and 112, respectively. The upper power supply 113 and the lower power supply 114 are controlled by a predetermined controller 250. The controller 250 adjusts the magnitudes of the first current and the second current to correct the density and uniformity of the plasma generated in the process chamber 130. According to embodiments of the present invention, the first current and the second current are preferably a direct current of approximately -10 to 10 amperes (A) in order to minimize shielding of the magnetic field by the process chamber 130. It can be adjusted as needed in the process.

According to one embodiment of the invention, the plasma 99 formed in the process chamber 130, by controlling the magnetic fields formed by the upper and lower Helmholtz coils (111, 112), the substrate 200 Can be concentrated on top. In this case, the density of the plasma 99 is increased, thereby increasing the productivity of the process.

3 and 4 are graphs for explaining the effect of the plasma chamber system according to the present invention. FIG. 3 shows a current of 4 amperes A to the lower Helmholtz coil 112 described with reference to FIG. 2, while a current applied to the upper Helmholtz coil 111 is 0, 4, -4 amperes A. FIG. In this case, the simulation result shows the strength of the magnetic field formed in the process chamber 130. As can be seen in Figure 3, by adjusting the strength of the current applied to the upper Helmholtz coil 111 and the lower Helmholtz coil 112, the strength of the magnetic field generated inside the process chamber 130 I can regulate it. In order to finely control the intensity of the magnetic field, the configuration of the upper and lower Helmholtz coils 111 and 112 may be variously modified.

FIG. 4 is a graph showing the ashing speed and the uniformity characteristic measured in the ashing apparatus employing the plasma chamber system described in FIG. 2.

Referring to FIG. 4, the graph of drawing instruction number 1 is a case where no current is applied to the upper Helmholtz coil 111 and the lower Helmholtz coil 112, and the graph of drawing instruction number 2 is the upper Helmholtz coil. In the case of applying currents of the same 4 amperes A to the coil 111 and the lower Helmholtz coil 112, the graph of reference numeral 3 is the upper Helmholtz coil 111 and the lower Helmholtz coil ( Experimental results are measured when 4 amps (A) and -4 amps (A) are applied to 112, respectively.

As can be seen from the experimental results, when the same currents are applied to the two coils 111 and 112 (see graph 2), the ashing rate increases while maintaining similar uniformity as compared with the case where no current is applied. do. This is the result because the axially uniform magnetic field formed by the superimposed magnetic fields influences the electron acceleration in the plasma 99, resulting in an overall increase in plasma density.

In contrast, when currents in different directions are applied to the two coils 111 and 112 (see graph 3), the ashing speed is further increased at the outside of the substrate than at the center of the substrate. This is a result of the non-uniform magnetic field is formed according to the radial distance of the wafer, as shown in Figure 3, the effect of increasing the plasma density by the trapping of secondary electrons on the substrate more effectively occurred at the outside of the substrate. If the ashing speed is slower at the outside than the center of the substrate, the ashing process applying this offset condition can correct the nonuniformity of the ashing process.

5 is a process flowchart illustrating the ashing method of the present invention for removing a photoresist pattern formed on a semiconductor substrate. 6 is a cross-sectional view illustrating an ashing process for removing a photoresist pattern formed on a low dielectric interlayer insulating film.

5 and 6, a low dielectric interlayer insulating film 320 is formed on the semiconductor substrate 200 (10). The interlayer insulating layer 320 is methylsilsesquioxane (MSQ), hydrogen silsesquioxane (HSQ), SiOF, SiOC, a-uorocarbon, SiLK, polyimides, spin-on-glasses, fluorinated polyimides, diamond-like carbon (DLC), Cyclotenes, Parylene N, Poly (arylene ethers), Poly (arylenes), Poly (norbornens), Polyimide-SSQ hybrids, Alkyl-silanes / N ₂ O, Teflon-AF, Teflon microemulsion, Polyimide nanofoams, silica aerogels, silica xerogels and Mesoporous silica It may be formed of at least one material selected. In the step 10 of forming the interlayer insulating layer 320, as described in the related art, a method of adding a process gas such as hydrogen or CH ₃ may be used. Pores may be formed in the interlayer insulating layer 320 to reduce the dielectric constant.

A photoresist pattern 330 used as an etch mask is formed on the resultant product on which the interlayer insulating layer 320 is formed (20). The photoresist pattern 330 may also be used as an ion implantation mask. The forming of the photoresist pattern 330 may include forming an opening for exposing the interlayer insulating layer 320 in a predetermined region by forming a photoresist layer using a spin-coating method and then exposing and developing the photoresist layer. Include. Before forming the photoresist layer, auxiliary layers 325 may be further formed on the interlayer insulating layer 320 such as an anti-reflection film, an etch stop film, and a protective film. In this case, an upper surface of the auxiliary layer 325 is exposed through the opening.

Next, the interlayer insulating layer 320 is patterned to form an opening 327 exposing the lower layer in a predetermined region (30). Accordingly, sidewalls of the interlayer insulating layer 320 are exposed at the openings 327. The patterning process may be performed by anisotropic etching using the photoresist pattern 320 as an etching mask.

After performing the patterning process, the photoresist pattern 330 used as an etching mask is removed (40). At this time, since the sidewall of the interlayer insulating film 320 is exposed, when applying a conventional ashing process using oxygen or hydrogen at a high temperature, as described in the prior art, it may cause a decrease in dielectric properties or mechanical damage of the interlayer insulating film. have. This problem can be overcome by performing the ashing process using a plasma chamber system having the upper and lower Helmholtz coils 111, 112 as described above.

More specifically, while maintaining the process chamber 130 at a temperature of approximately 0 to 80 ℃, the ashing gas is supplied to the interior of the process chamber 130 through the supply pipe 170 at a flow rate of 30 to 3000sccm. At this time, the internal pressure of the process chamber 130 is preferably maintained at 10 to 600 millitorr (mT). In addition, power of approximately 100 to 2500 watts is applied to the chuck 180. Accordingly, the ions 350 generated in the ashing gas have a direction moving toward the upper surface of the substrate 200, as shown in FIG. The oxygen radicals 340 are activated by the collision with the ions 350. Activated oxygen radicals 340 participate in the process of removing the photoresist.

Meanwhile, the density of the plasma formed on the substrate 200 is controlled at the same time by the magnetic field controlled by the upper and lower Helmholtz coils 111 and 112. As a result, the density of the ions 350 activating the oxygen radical 340 increases. Accordingly, the oxygen radicals 340 may effectively remove the photoresist pattern 330 even at a process condition other than a high temperature as in the prior art.

 As a result, the shape of the interlayer insulating film to which the ashing process according to the present invention is applied (see the picture of FIG. 7B) is not different from the shape of the interlayer insulating film before the ashing process is applied (see the picture of FIG. 7A). That is, the ashing process according to the present invention can remove the photoresist pattern without damaging the low dielectric interlayer insulating film.

According to the invention, upper and lower Helmholtz coils which can be independently controlled are arranged at the top and bottom of the plasma process chamber. Accordingly, the density of the plasma generated in the process chamber can be controlled according to the position.

In addition, by performing the ashing process using such a plasma process chamber, it is possible to remove the photoresist without causing damage to the low dielectric film even in process conditions other than high temperature.

Claims (9)

Process chambers; A wafer chuck disposed in the process chamber; A lower radio-frequency power source electrically connected to the wafer chuck; An upper electrode disposed on the wafer chuck; An upper Helmholtz coil disposed above the process chamber; And And a lower Helmholtz coil disposed below the process chamber. The method of claim 1, An upper power supply for supplying a first current to the upper Helmholtz coil; And Further provided with a lower power supply for supplying a second current to the lower Helmholtz coil, The first current is a direct current of approximately -10 to 10 amperes (A), And said second current is a direct current of approximately -10 to 10 amperes (A). The method of claim 2, And a controller connected to the upper power source and the lower power source to adjust the magnitudes of the first current and the second current to correct the density and uniformity of plasma generated in the process chamber. Forming a low dielectric film on the semiconductor substrate; Forming a photoresist pattern on the semiconductor substrate including the low dielectric film; Loading the semiconductor substrate including the photoresist pattern into an ashing chamber having an upper helmholtz coil and a lower helmholtz coil disposed at upper and lower portions thereof, and an upper electrode and a lower electrode disposed therein; And Removing the photoresist pattern while supplying an ashing gas containing oxygen into the ashing chamber, The removing of the photoresist pattern may include applying a first DC current and a second DC current to the upper Helmholtz coil and the lower Helmholtz coil, respectively, while maintaining the internal temperature of the ashing chamber at approximately 0 to 80 ° C. An ashing method for a photoresist pattern, characterized in that. The method of claim 4, wherein The ashing gas ashing method of the photoresist pattern, characterized in that it comprises at least one gas and oxygen gas selected from the group of additive gases consisting of nitrogen gas, inert gas, reducing gas and carbon fluoride (CF) -based gas. The method of claim 4, wherein The ashing gas is nitrogen (N ₂ ) gas, helium (He) gas, argon (Ar) gas, hydrogen (H ₂ ) gas, helium hydrogen (H ₂ He) gas, nitrogen hydrogen (H ₂ N ₂ ) gas, mute The ashing method of the photoresist pattern, characterized in that it comprises at least one gas selected from carbon (CF ₄ ) and methane trifluoride (CHF ₃ ) and oxygen gas. The method of claim 4, wherein And the first direct current and the second direct current are independently adjusted to positionally control the density of plasma formed in the ashing chamber. The method of claim 7, wherein The first current is determined in the range of approximately -10 to 10 amperes (A), And the second current is determined in the range of approximately -10 to 10 amperes (A). The method of claim 4, wherein Removing the photoresist is Applying approximately 100 to 2500 watts of power to the bottom electrode; And And ashing the inner pressure of the ashing chamber at 10 to 600 millitorr (mT).

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