JP2010267670A - Plasma processing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform uniform and consistent processing on each of films of a laminated film composed of an organic film and an inorganic film. <P>SOLUTION: A plasma processing method uses a vacuum container 1 including a gas supply pipe for supplying a processing gas, a substrate electrode 3 arranged in the vacuum container, an antenna electrode 7 arranged in the vacuum container opposite the substrate electrode, and an inter-electrode distance adjusting means of varying the distance between the substrate electrode and antenna electrode in a processing atmosphere. The method includes: generating plasma by supplying high-frequency energy to the processing gas supplied by supplying high-frequency energy to the antenna electrode; supplying a high-frequency voltage for attracting ions to the substrate electrode; and accelerating ions in the generated plasma to perform plasma processing on a sample mounted on the substrate electrode. The sample has an insulating film structure having a structure having the organic film and inorganic film laminated, and the inter-electrode distance during etching the organic film is set to be larger than that during etching the inorganic film. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a plasma processing method, and more particularly to a plasma processing method capable of uniformly processing a plurality of types of films uniformly.

  In recent years, with higher integration of semiconductor elements, miniaturization of wiring, thinning, multilayering, and wafer diameters have increased, and device structures have become increasingly complex, requiring more advanced processing techniques. I came.

  Further, in order to reduce the manufacturing cost of the semiconductor device, it is desired that the laminated film including the organic film and the inorganic film having different etching characteristics be processed consistently in the same apparatus.

  In response to such a request, Patent Document 1 discloses that a parallel plate ECR (Electron Cyclotron Resonance) plasma apparatus using UHF (Ultra High Frequency) is used to adjust the magnetic field distribution and control the location where electron cyclotron resonance occurs. A technique for generating an optimum plasma by arbitrarily controlling the plasma distribution according to the process conditions is shown.

  Further, Patent Document 2 includes a plurality of gas ejection ports formed in a gas ejection plate on the facing surface of the substrate to be processed, and jets mixed gases having different flow ratios from different gas ejection ports. A technique for improving the non-uniform distribution of the concentration of active species and the concentration of by-product gas and making the plasma processing on the substrate to be processed uniform is shown.

Japanese Patent Laid-Open No. 2001-110783 JP 2008-166853 A

  As described above, the processing dimensions in the semiconductor manufacturing process and the diversification of materials are continuing, and for example, as a material to be etched, for a laminated film including an organic film and an inorganic film having different etching characteristics, There is a need for optimal uniformity control.

  In a plasma processing apparatus, in order to perform uniform plasma processing on a substrate to be processed, it is important to distribute active species such as ions and radicals related to the plasma processing at a uniform concentration over the entire processing surface of the substrate to be processed. .

  In the case of a plasma processing apparatus, the distribution of ions that are one of the active species is related to the plasma density distribution. As a technique for making the plasma density distribution uniform, a technique such as the magnetic field distribution control in the electron cyclotron resonance described above is used. Has been used.

  Regarding radicals, which are another active species, even if the plasma density distribution is made uniform, it may become non-uniform depending on the degree of dissociation that occurs from the etching gas outlet to the substrate. is there.

  That is, the longer the time the gas stays in the plasma, the more dissociation proceeds, so the amount of radicals increases. On the other hand, the shorter the time the gas stays in the plasma, the lower the progress of dissociation, so the amount of radicals decreases. Thereby, nonuniformity occurs in the distribution of radicals.

  For example, in the case of etching an organic film, the reaction rate due to the organic film and radicals is fast, and thus the etching is dominant in radical distribution. However, the dissociation of the plasma proceeds as the gas supplied from the vicinity of the center of the gas ejection holes formed in a narrow space as in the plasma processing apparatus reaches the outer periphery of the substrate to be processed. For this reason, a difference occurs in the radical distribution from the central part to the outer peripheral part, and the etching characteristics differ in the radial direction.

  In order to improve this problem, it is conceivable to adjust the radical distribution by adjusting the gas injection range in a hardware manner or by jetting gases having different mixing ratios from different gas outlets as described above. However, these proposals have a complicated structure, and the optimum hardware configuration differs depending on conditions such as the gas flow rate and the pressure in the processing chamber. For this reason, it is difficult to optimize each film when processing laminated films having different film types.

  The present invention has been made in view of these problems, and provides a plasma processing method capable of uniformly processing a plurality of laminated films having different film types.

  In order to solve the above problems, the present invention employs the following means.

A vacuum vessel provided with a gas supply pipe for supplying a processing gas, a substrate electrode arranged in the vacuum vessel, an antenna electrode arranged in the vacuum vessel facing the substrate electrode,
Inter-electrode distance adjusting means capable of changing the distance between the substrate electrode and the antenna electrode in a processing atmosphere, supplying the high-frequency energy to the antenna electrode and supplying the high-frequency energy to the processing gas supplied to the plasma In the plasma processing method of supplying a high frequency voltage for ion attraction to the substrate electrode, accelerating ions in the generated plasma and performing plasma processing on the sample placed on the substrate electrode, The sample has an insulating film structure having a structure in which an organic film and an inorganic film are laminated. When the organic film is etched, the distance between the electrodes is set larger than when the inorganic film is etched.

  Since this invention is provided with the above structure, a consistent process can be uniformly performed with respect to several laminated film from which film | membrane types differ.

It is a figure explaining a parallel plate type ECR plasma etching apparatus. It is a figure explaining a to-be-processed substrate. It is a figure which shows the relationship between an electrode space | interval and in-plane uniformity of an etching rate. It is a figure explaining a to-be-processed substrate. It is a figure explaining the etching conditions in each step.

  Hereinafter, embodiments will be described with reference to the accompanying drawings. FIG. 1 is a longitudinal sectional view showing an example of a parallel plate type ECR plasma etching apparatus using UHF for carrying out the plasma etching method of the present invention.

  As shown in FIG. 1, a substrate electrode (lower electrode) 3 on which a substrate 2 to be processed is placed and an antenna electrode (upper electrode) 7 disposed to face the substrate electrode 3 are provided in a vacuum vessel 1. It is done. The substrate electrode 3 is provided with an electrostatic chuck 4 for attracting and holding the substrate 2 to be processed. The electrostatic chuck 4 is used for applying a high frequency bias when the substrate 2 is subjected to plasma processing. A high frequency power supply 5 is connected via a matching unit 6.

  The substrate electrode 3 is configured to be movable in the vertical direction by a driving unit (not shown), and the distance from the antenna electrode 7 can be adjusted. A conductive gas supply plate 8 connected to a process gas supply pipe 14 (not shown) is provided on the surface of the antenna electrode 7 on the substrate electrode 3 side. A high frequency power source 9 for plasma generation and a high frequency power source 11 for bias application are connected to the antenna electrode 7 via a matching unit 10 and a matching unit 12, respectively. A coil 13 for forming a magnetic field in the vacuum vessel 1 is provided on the outer peripheral portion of the vacuum vessel 1. The processing gas is introduced into the gas inlets 15 a and 15 b, passes through the gas introduction passages formed in the antenna electrode 7 and the gas supply plate 8, and further passes through the gas discharge ports 16 provided in the gas supply plate 8 to the etching chamber. Is ejected. A mixed gas whose flow rate and flow rate ratio are adjusted by a plurality of mass flow controllers flows out from a large number of gas ejection ports.

  The etching apparatus configured as described above supplies a processing gas into the vacuum vessel 1 and evacuates the inside to a predetermined pressure by an exhaust apparatus (not shown) during processing. In addition, high frequency power is supplied from the high frequency power source 9 to the antenna electrode 7 and a current for forming a magnetic field is supplied to the coil 13 to generate plasma in the vacuum chamber 1. Further, by applying a high frequency bias to the substrate electrode 3 and the antenna electrode 7 from the high frequency power source 5 and the high frequency power source 11, respectively, the substrate 2 to be processed on the substrate electrode 3 is etched.

  FIG. 2 is a diagram for explaining a substrate to be processed, which is a laminated insulating film having a multilayer resist structure. In the example of this figure, a via formation process will be described.

  As shown in FIG. 2A, the substrate to be processed includes an ArF resist 201 that is a first film, an inorganic film intermediate layer 202 that is a second film, an organic film lower layer resist 203 that is a third film, A silicon oxide film 204 as a fourth film, an inorganic film 205 as a fifth film, and a Si substrate 206 as a sixth film.

  First, in the first step, the organic film lower layer resist 203 is exposed from the inorganic film intermediate layer 202 using the patterned ArF resist 201 on the inorganic film intermediate layer 202 as a mask as shown in FIG. Etch until.

  In the second step, as shown in FIG. 2C, the organic film lower layer resist 203 is etched until the silicon oxide film 204 is exposed using the ArF resist 201 and the inorganic film intermediate layer 202 as a mask.

  In the third step, as shown in FIG. 2D, using the organic film lower layer resist 203 as a mask, the Si oxide film 204 and the inorganic film 205 are etched until the Si substrate 206 is exposed.

  In the fourth step, as shown in FIG. 2E, the remaining organic film lower layer resist 203 is ashed without carrying out the substrate to be processed from the processing chamber.

  FIG. 5 is a diagram for explaining the etching conditions of these steps.

  FIG. 3 shows the distance between the antenna electrode 7 and the substrate electrode 3, more specifically, the distance between the gas supply plate 8 as a conductor and the substrate 2 to be processed (electrode spacing), and the in-plane uniformity of the etching rate on the substrate to be processed. It is a figure which shows the relationship with sex.

  Referring to the figure, it can be seen that in the etching of the inorganic film intermediate layer 202 in the first step, the in-plane uniformity is improved as the electrode interval is shortened as shown in FIG.

  In other words, the plasma density distribution is made uniform by shortening the distance between the antenna electrode 7 and the substrate electrode 3 and narrowing the plasma diffusion range under the condition that the plasma optimized by the magnetic field exists. It is considered that the in-plane uniformity is improved by the uniform incidence of ions on the substrate 2 over a wide range.

  In the etching of the organic film lower layer resist 203 in the second step, it can be seen that the in-plane uniformity is improved as the electrode interval is increased as shown in FIG.

  That is, the distance between the antenna electrode 7 and the substrate electrode 3 is widened to move the substrate 2 to be processed away from the plasma generation region. In this case, the dissociation of plasma proceeds more than the state in which the distance between both electrodes is narrow before reaching the surface of the substrate to be processed. For this reason, it is considered that the etchant (radical) supplied from the gas ejection holes is evenly diffused in the plane, and the uniformity of radical distribution on the substrate 2 to be processed is improved.

  In the etching of the silicon oxide film 204 and the inorganic film 205 in the third step, it can be seen that the in-plane uniformity is improved as the electrode interval is shortened as shown in FIG.

  That is, by reducing the distance between the antenna electrode 7 and the substrate electrode 3 as in the first step, the plasma diffusion range is narrowed, and the plasma density distribution is close to uniform, thereby improving in-plane uniformity. I think.

  Therefore, when etching a substrate to be processed having a structure in which an inorganic film and an organic film are laminated, the electrode interval of the etching apparatus is narrowed when the inorganic film is etched and widened when the organic film is etched. In-plane uniformity of the etching rate during film processing can be improved. Thereby, the comprehensive in-plane uniformity of the laminated | stacked several film | membrane can be improved.

  Further, these laminated films can be etched in the same vacuum container only by changing the etching conditions. For this reason, the to-be-etched material of a multilayer resist laminated insulating film structure can be processed uniformly and uniformly.

  In the above example, as shown in FIG. 2, the process of creating a via in the material to be etched has been described, but the process of creating a trench can be similarly performed.

  FIG. 4 is a diagram for explaining a substrate to be processed, which is a laminated insulating film having a multilayer resist structure. In the example of this figure, a trench formation process will be described.

  As shown in FIG. 4, the substrate to be processed includes an ArF resist 401 as a first film, an inorganic film intermediate layer 402 as a second film, an organic film lower layer resist 403 as a third film, and a fourth film. A silicon oxide film 404, a fifth film, an inorganic film 405, and a sixth film, a Si substrate 406.

  In the first step, as shown in FIG. 4B, using the ArF resist 401 patterned on the inorganic film intermediate layer 402 as a mask, the inorganic film intermediate layer 402 is etched until the organic film lower layer resist 403 is exposed. To do.

  In the second step, as shown in FIG. 4C, using the ArF resist 401 and the inorganic film intermediate layer 402 as a mask, the organic film lower layer resist 403 is etched until the silicon oxide film 404 is exposed.

  In the third step, as shown in FIG. 4D, the Si oxide film 404 and the inorganic film 405 are etched until the Si substrate 406 is exposed using the organic film lower layer resist 403 as a mask.

  In the fourth step, as shown in FIG. 4E, the remaining organic film lower layer resist 403 is ashed without carrying out the substrate to be processed from the processing chamber.

  Since the substrate having such a trench structure also has a structure in which an inorganic film and an organic film are laminated, the in-plane uniformity is improved by performing an etching process while changing the electrode interval in the same manner as in the above example. Can be processed consistently.

  As described above, according to this embodiment, by adjusting the distance between the upper electrode and the lower electrode for each film type, the active species such as ions and radicals supplied to the substrate to be processed can be changed to the properties of the film type. Therefore, processing with high in-plane uniformity can be performed in a consistent process even on a laminated film including an organic film and an inorganic film in the same substrate to be processed.

1 Vacuum container 2 Substrate 3 Substrate electrode 4 Electrostatic chuck 5 High frequency power supply 6 Matching device 7 Antenna electrode
8 Gas supply plate 9 High frequency power supply 10 Matching device 11 High frequency power supply 12 Matching device 13 Coil 14 Gas supply pipes 15a and 15b Gas introduction port 16 Gas ejection port 201 ArF resist 202 Inorganic film intermediate layer 203 Organic film lower layer resist 204 Silicon oxide film 205 Inorganic film 206 Si substrate 401 ArF resist 402 Inorganic film intermediate layer 403 Organic film lower layer resist 404 Silicon oxide film 405 Inorganic film 406 Si substrate

Claims (3)

A vacuum vessel provided with a gas supply pipe for supplying a processing gas;
A substrate electrode disposed in the vacuum vessel;
An antenna electrode disposed opposite to the substrate electrode in the vacuum vessel;
An inter-electrode distance adjusting means capable of changing a distance between the substrate electrode and the antenna electrode in a processing atmosphere;
Supplying high-frequency energy to the antenna electrode and supplying high-frequency energy to the supplied processing gas to generate plasma, supplying a high-frequency voltage for ion attraction to the substrate electrode, and generating ions in the generated plasma In the plasma processing method of performing plasma processing on the sample that is accelerated and placed on the substrate electrode,
The sample has an insulating film structure having a structure in which an organic film and an inorganic film are stacked, and when the organic film is etched, the distance between the electrodes is set larger than when the inorganic film is etched. A plasma processing method. A vacuum vessel provided with a gas supply pipe for supplying a processing gas;
A substrate electrode disposed in the vacuum vessel;
An antenna electrode disposed opposite the substrate electrode in the vacuum vessel;
An inter-electrode distance adjusting means capable of changing a distance between the substrate electrode and the antenna electrode in a processing atmosphere;
Supplying high-frequency energy to the antenna electrode and supplying high-frequency energy to the supplied processing gas to generate plasma, supplying a high-frequency voltage for ion attraction to the substrate electrode, and generating ions in the generated plasma In the plasma processing method of accelerating and performing plasma processing on a sample placed on the substrate electrode, the sample has a structure in which an organic film resist and an inorganic film intermediate layer are stacked on a silicon oxide film, and the distance between the electrodes is narrowed. In this state, using the ArF resist formed on the inorganic film intermediate layer as a mask, the inorganic film intermediate layer is etched until the lower organic film resist is exposed, and the distance between the electrodes is increased and the ArF resist and inorganic The organic film resist is etched until the underlying silicon oxide film is exposed using the film intermediate layer as a mask. Plasma processing method. The plasma processing method according to claim 1,
The plasma processing method, wherein the inter-electrode distance adjusting means is a driving means for driving the substrate electrode in the vertical direction.

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