JP6551673B2 - Plasma processing apparatus and plasma processing method - Google Patents

Description

  The present invention relates to a plasma processing apparatus and a plasma processing method using inductively coupled plasma.

  As an inductively coupled plasma (ICP) type plasma processing apparatus, a configuration is known in which an upper part of a reaction chamber is closed with a plate-shaped dielectric member, and an induction coil for supplying high-frequency power is disposed on the dielectric member. It is done. A cover is provided in the reaction chamber to cover the dielectric member to protect the expensive dielectric member from plasma. Since the reaction chamber is depressurized, the dielectric member is required to have a thickness for securing mechanical strength to support the atmospheric pressure.

  In recent years, the reaction chamber of the plasma processing apparatus has been enlarged in order to cope with the increase in the diameter of the substrate to be processed (diameter 300 mm, diameter 450 mm, etc.). Along with this, a dielectric member serving as a window for introducing a high frequency into the reaction chamber is also enlarged. And the thickness of the dielectric member is also increasing in order to ensure the mechanical strength of the large-dielectric member. However, the greater the thickness of the dielectric member, the greater the loss of high frequency power input from the induction coil to the plasma, making it difficult to generate a high density plasma.

  On the other hand, in the plasma dicing method in which a silicon substrate is singulated using plasma, high speed processing (≧ 10 μm / min) of silicon is required to increase throughput. In order to improve the processing speed of silicon, a high plasma density is required. Moreover, in order to ensure in-plane uniformity of processing speed, highly uniform plasma distribution is also required.

  As described above, a plasma processing apparatus is required to generate a large area, high density, and highly uniform plasma. Furthermore, in addition to silicon, it may be necessary to process metal films, dielectric films, and compound semiconductors. In order to enable processing under etching conditions suitable for each film type, plasma is used in a wide pressure range. Is also required to be generated.

  Patent Document 1 proposes that the lower surface side of the dielectric member is supported by a beam-like structure. As a result, the dielectric member can be thinned and the induction coil can be brought close to the plasma, so that it is possible to achieve both of securing of the mechanical strength and improvement of the plasma density.

  However, because the beam-like structure forms irregularities on the lower surface side of the dielectric member, the structure of the upper part of the reaction chamber becomes complicated, and the labor of apparatus maintenance increases. In addition, unevenness due to the beam-like structure may adversely affect the distribution of plasma. There is also a limit to the pressure range in which plasma can be generated.

  JP 2008-306042 A

  Even when the apparatus is increased in size, the loss of the high frequency power input from the induction coil to the plasma is small, and even if the high frequency power input from the induction coil to the plasma is large, The present invention provides a plasma processing apparatus and a plasma processing method capable of suppressing consumption. Moreover, according to the present invention, a plasma processing apparatus having a simple structure and excellent maintainability can be provided.

One aspect of the present invention includes a container having a reaction chamber, a stage that supports an object to be processed in the reaction chamber, a dielectric member that closes the opening of the container and faces the stage, and the dielectric in the reaction chamber. A cover installed to cover the body member; and an induction coil installed outside the reaction chamber of the dielectric member and generating plasma in the reaction chamber, the reaction of the dielectric member An annular groove is formed on the outer surface with respect to the chamber, at least a portion of said induction coil, said is disposed in the groove, the surface of the front Symbol stage side of said cover, said dielectric And a first region that covers a region in which the groove of the member is formed, a region inside the region, and an annular second region that surrounds the first region, and the first region is formed of aluminum nitride. The second region is nitrided It is formed of a dielectric material other than aluminum, a plasma processing apparatus.

Another aspect of the present invention includes: (i) a step of supporting an object to be processed on a stage installed in a reaction chamber; and (ii) an induction coil installed outside a dielectric member partitioning the reaction chamber, Applying electric power to generate plasma in the reaction chamber and plasma-treating the object to be processed, and in the reaction chamber, a cover is installed so as to cover the dielectric member, wherein An annular groove is formed on the outer surface with respect to the reaction chamber of the dielectric member, at least a portion of said induction coil, said is disposed in the groove, prior Symbol stage side of the cover The surface of the dielectric member has a region where the groove is formed, a first region covering the region inside the region, and an annular second region surrounding the first region, and the first region Is formed of aluminum nitride, and the second region is nitrided. It is formed of a dielectric material other than aluminum, a plasma processing method.

  According to the plasma processing apparatus and the plasma processing method of the present invention, since at least part of the induction coil is disposed in the groove formed on the outer surface of the dielectric member, the induction coil is charged into the plasma. High frequency power loss is reduced. In addition, since the surface on the reaction chamber side of the dielectric member can be a flat surface without irregularities, maintenance becomes easy and distribution of plasma also becomes good. In the above configuration, the plasma generation portion is localized in the reaction chamber immediately below the groove. On the other hand, at least a part of the portion facing the groove is formed of aluminum nitride on the stage side surface of the cover for protecting the dielectric member. Therefore, wear of the cover is suppressed.

It is sectional drawing which shows typically the structure of the plasma processing apparatus which concerns on 1st Embodiment of this invention. It is the longitudinal cross-sectional view (a) which shows typically the arrangement | positioning of the dielectric material member and coil which concern on 1st Embodiment, and the top view (b) of the same dielectric material material. It is the longitudinal cross-sectional view (a) which shows typically a structure of an example of an electrode pattern containing a dielectric material member and a Faraday shield (FS) electrode, and the longitudinal cross-sectional view (b) which expanded this to the vertical direction. It is a top view of the 1st electrode pattern (electric heater) concerning a 1st embodiment. It is a top view of the 2nd electrode pattern (flat plate electrode (FS electrode)) concerning a 1st embodiment. It is sectional drawing which shows typically the structure of the plasma processing apparatus which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows typically the structure of the plasma processing apparatus which concerns on 3rd Embodiment of this invention. It is sectional drawing which shows typically the structure of the dielectric material member used for the comparative experiment of the discharge stable area | region. It is a figure which shows the result of the comparative experiment of a discharge stable area | region.

  A plasma processing apparatus according to an embodiment of the present invention includes a container having a reaction chamber, a stage that supports an object to be processed in the reaction chamber, a dielectric member that closes the opening of the container and faces the stage, and a dielectric in the reaction chamber. A cover disposed to cover the body member, and an induction coil disposed outside the reaction chamber of the dielectric member for generating plasma in the reaction chamber. A groove is formed on the outer surface of the dielectric member with respect to the reaction chamber, and at least a portion of the induction coil is disposed in the groove. As a result, the distance between the portion of the induction coil placed in the groove and the plasma is reduced, so the loss of high frequency power is suppressed. On the other hand, the plasma generating portion concentrates directly below the groove, but at least the surface of the cover on the stage side has a first region formed of aluminum nitride, and at least a part of the first region faces the groove. Consumption of the cover is suppressed.

  The surface on the stage side of the cover may have a second region different from the first region. The second region may be formed of a dielectric material other than aluminum nitride (for example, quartz or alumina). This makes it possible to significantly reduce the manufacturing cost of the cover. Further, at least a portion of the cover facing the groove only needs to be formed of aluminum nitride up to a depth of 10 μm or more from the surface on the stage side.

  The first area is preferably detachable from the second area. Thereby, the maintenance of the plasma processing apparatus is further simplified, and the cost required for the cover can be easily reduced.

  The groove is preferably annular with the same center as the center of the coil. This facilitates placing the induction coil in the groove. In this case, the first region is also preferably circular or annular, which facilitates the manufacture of the cover.

  The plasma processing apparatus preferably further comprises a faraday shield electrode (FS electrode) disposed on the side opposite to the cover stage. Thereby, adhesion of a non-volatile substance to a cover can be suppressed, suppressing consumption of a cover.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the following drawings and description do not limit the present invention.
First Embodiment
FIG. 1 shows a configuration of an inductively coupled plasma (ICP) type dry etching apparatus 10 which is a plasma processing apparatus according to a first embodiment of the present invention. The dry etching apparatus 10 includes a container 1 having a reaction chamber 1a that can be depressurized, a stage 2 that supports an object to be processed (the substrate 15 in this case) in the reaction chamber 1a, and closes the opening of the container 1 and faces the stage 2 A dielectric member 3 that is disposed outside the reaction chamber 1a of the dielectric member 3 and generates plasma in the reaction chamber 1a, and the dielectric member 3 is covered in the reaction chamber 1a. And a cover 5 installed.

  The container 1 is generally cylindrical with an open top, and the top opening is sealed by a dielectric member 3 which is a lid. The reaction chamber 1a is evacuated by a predetermined exhaust device (not shown) and maintained in a reduced pressure atmosphere. The container 1 is provided with a gate (not shown) for carrying the substrate 15 in and out. The stage 2 has a built-in lower electrode, and a bias voltage is applied to the lower electrode. The stage 2 can be provided with a function of holding the substrate 15 by electrostatic adsorption and a circulation path for the refrigerant.

  The dielectric member 3 is generally in the form of a circular plate along the opening shape of the container 1. A groove 3 a is formed on the outer surface of the dielectric member 3 with respect to the reaction chamber 1 a in order to partially thin the dielectric member 3. At least a portion of induction coil 4 is disposed in groove 3a. Thereby, the part arrange | positioned in the groove | channel 3a of the induction coil 4 becomes short distance with plasma. Therefore, the loss of high frequency power is suppressed. On the other hand, the groove 3a is annularly formed on a part of the surface of the plate-like dielectric member 3, and the central portion of the dielectric member 3 has a thickness, so that mechanical properties of the dielectric member 3 are obtained. The strength does not decrease significantly. Note that simulation is performed by calculating and comparing the amount of deflection when an equal load is applied to one surface of a dielectric member, for two types of dielectric members in which a groove is formed and a dielectric member in which a groove is not formed. As a result, it has been found that the amount of bending of the two is substantially the same.

  The dielectric member 3 has flat both sides when the groove 3a is not formed. The thickness of the portion without the groove 3a needs to be set so that the dielectric member has a predetermined strength. For this reason, the amount of deflection in the case where an even load is applied to one surface of the dielectric member is calculated, and the thickness of the portion of the dielectric member 3 without the groove 3a is calculated so that the amount of deflection does not exceed the reference value. Set This thickness is, for example, 35 to 40 mm when the diameter of the dielectric member 3 is 540 mm.

  A first holder 17 that supports the cover 5 and a second holder 18 that supports the dielectric member 3 are provided at the upper end of the side wall of the container 1. The cover 5 is supported on the first holder 17 via the second elastic ring 14. The cover 5 is formed of nitrogen aluminum (AlN). The peripheral portion of the cover 5 is fixed by a second holder 18 that supports the dielectric member 3. The dielectric member 3 is supported on the second holder 18 via the first elastic ring 13. The cover 5 serves to protect the surface of the dielectric member 3 on the reaction chamber 1a side from plasma.

  The second holder 18 is provided with a gas inlet 8 for introducing a source gas (process gas) of plasma from a predetermined gas supply source into the reaction chamber 1a. After staying in the minute gap 8 a formed between the dielectric member 3 and the cover 5, the process gas is jetted into the reaction chamber 1 a from the plurality of gas jet holes 9 provided on the cover 5. The plurality of gas ejection ports 9 are preferably distributed concentrically, for example.

  FIG. 2A schematically shows the arrangement of the dielectric member 3 and the induction coil 4 according to this embodiment. When the induction coil 4 is viewed in a direction perpendicular to (the surface direction of) the dielectric member 3, the induction coil 4 is formed of a conductor 4 a spirally extending from the center to the outer peripheral side. The conductor 4a may be, for example, a ribbon-like metal plate or a metal wire. The number of conductors a forming the induction coil 4 is not particularly limited, and the shape of the induction coil 4 is not particularly limited. For example, a single spiral type coil composed of one conductor 4a or a multi spiral type coil in which induction coils composed of a plurality of conductors 4a are connected in parallel may be used. Alternatively, it may be a flat type coil formed by spirally extending the conductor 4a in the same plane parallel to the surface of the dielectric member 3, or the surface of the dielectric member 3 while spirally extending the conductor 4a. Alternatively, a three-dimensional coil having a change in the vertical direction may be used. The induction coil 4 is electrically connected to the first high frequency power supply 11 via a matching circuit (not shown) or the like. In FIGS. 1 and 2, the distance from the dielectric member 3 in the vicinity of the center of the induction coil 4 is larger than that on the outer peripheral side, but the positional relationship between the induction coil 4 and the dielectric member 3 is It is not limited to.

  As shown in FIG. 2B, the groove 3 a is preferably annular having the same center as the center of the induction coil 4. Thereby, it becomes easy to arrange | position the induction coil 4 in the groove | channel 3a. In addition, that the centers of the induction coil 4 and the annular groove 3a are the same does not necessarily mean that the respective centers coincide. Here, the centers of the induction coil 4 and the annular groove 3 a are the same when the dielectric member 3 and the induction coil 4 are viewed from a direction perpendicular to the dielectric member 3. It means that it exists in a circle with a radius of 100 mm.

  The depth of the groove 3a is not particularly limited. Even if the depth of the groove 3a is small, a corresponding effect of suppressing the loss of high frequency power can be obtained. However, when the thickness of the plate-like dielectric member 3 having a uniform thickness before forming the groove 3a is T, the maximum depth D of the groove 3a is D = 0.14T to 0.71T. It is preferable to form as follows. More preferably, it is formed so that D = 0.28T to 0.57T. At this time, from the viewpoint of securing the strength, the ratio (100 s / S (%)) of the area s where the groove 3a is dug out of the surface area S where the groove 3a of the dielectric member 3 is formed is 5 to 50%. It is preferable to

  The groove 3a may be formed by machining a dielectric member, such as cutting one surface of a plate-like dielectric member having flat surfaces on both sides and a uniform thickness. When cutting is performed, micro cracks (micro cracks) are formed on the processed surface, and the strength of the dielectric member may be reduced. In this case, after cutting, it is desirable to perform post-processing such as lapping (polishing) to remove the microcracks.

  By flowing a high frequency current through the induction coil 4, plasma (inductively coupled plasma) is generated in a region near the induction coil 4 in the upper part of the reaction chamber 1 a. The degree of inductive coupling between the induction coil 4 and the plasma can be increased by reducing the distance between the induction coil 4 and the reaction chamber 1 a or increasing the density of the induction coil 4.

  In order to obtain a plasma with good in-plane uniformity on the surface of the substrate 15, a plasma having a distribution (doughnut-shaped distribution) in which the plasma density in the outer peripheral portion is higher than the plasma density in the vicinity of the center in the upper part of the reaction chamber 1a. Are preferably diffused onto the substrate. In order to form a plasma having a doughnut-shaped distribution in the upper part of the reaction chamber 1a, the distance between the induction coil 4 near the center and the reaction chamber 1a may be relatively increased. The degree of coupling with can be reduced. Therefore, the center side of the induction coil 4 may not be arranged in the groove 3a. As shown in FIGS. 1 and 2, at least a portion corresponding to the center of the induction coil 4 may be disposed completely outside the groove 3a.

  On the other hand, at the outer peripheral portion of the induction coil 4, the induction coil 4 is disposed in the groove 3a, and the induction coil 4 and the plasma are coupled to each other by relatively reducing the distance between the induction coil 4 and the reaction chamber 1a. The degree of can be increased. Therefore, when the conductor 4a having a length L forming the induction coil 4 is divided into a center side portion from the center to 0.5L and the remaining outer peripheral side portion, the center side portion is disposed in the groove 3a. It is preferable to make the ratio at which the outer peripheral portion is disposed in the groove 3a larger than the ratio. Further, it is preferable that at least a part corresponding to the outermost periphery of the induction coil 4 is disposed in the groove 3a. Furthermore, it is preferable that at least a part of the outer peripheral side portion from at least the outermost end (winding end) to 0.3 L is disposed in the groove 3a.

  At this time, in the induction coil 4, it is preferable to make the coil density of the outer peripheral part larger than the coil density of the central part. That is, when viewed from a direction perpendicular to the dielectric member 3, the portion closer to the center (start of winding) of the induction coil 4 is closer to the gap between the adjacent conductors 4a (the direction parallel to the surface direction of the dielectric member 3). It is preferable that the gap between the adjacent conductors 4a be narrower as the distance between the adjacent conductors 4a is larger and the portion closer to the outer peripheral side. Thereby, the degree of the coupling | bonding of the induction coil 4 and plasma in an outer peripheral part can be made higher. On the other hand, in the vicinity of the center, it is possible to suppress that the dielectric member 3 and the cover 5 are scraped and deteriorated by plasma.

As materials for forming the container 1, the first holder 17, the second holder 18, etc., metal materials having sufficient rigidity such as aluminum and stainless steel (SUS), aluminum with anodized surface, etc. can be used. . As a material constituting the dielectric member 3, a dielectric material such as yttrium oxide (Y ₂ O ₃ ), aluminum nitride (AlN), alumina (Al ₂ O ₃ ), quartz (SiO ₂ ), or the like can be used. On the other hand, at least the surface of the cover 5 on the stage 2 side has a first region formed of at least aluminum nitride (AlN). However, the first region is formed to include at least a part of the portion of the dielectric member 3 facing the groove 3 a. In addition to the first region of the cover 5, a dielectric material such as yttrium oxide (Y ₂ O ₃ ), alumina (Al ₂ O ₃ ), or quartz can be used.

  When at least a part of the induction coil 4 is disposed in the groove 3a of the dielectric member 3, the plasma generation part is likely to be localized in the reaction chamber 1a immediately below the groove 3a. Thereby, the surface (inner surface Sa) on the stage 2 side of the cover 5 is locally exposed to the high density plasma. Of the inner surface Sa, the portion ARcv facing the groove 3a is particularly easily exposed to high-density plasma, for example, easily eroded by fluorine-based plasma. On the other hand, by forming the cover 5 of aluminum nitride, the consumption of the cover 5 due to the erosion of the fluorine-based plasma is significantly suppressed. Since the consumption of the cover 5 is suppressed, the frequency of replacement of the cover 5 can be reduced, and the productivity of the plasma processing apparatus can be enhanced. When the dielectric member 3 and the cover 5 are viewed in the normal direction, the portion of the inner surface Sa overlapping the groove 3a is ARcv.

  Aluminum nitride is particularly resistant to plasma, and is not easily eroded even when exposed to fluorine radicals frequently used in dry etching equipment, for example. Aluminum nitride is resistant to thermal shock and has excellent thermal conductivity. Therefore, the heat received from the plasma can be transferred to the outside with high efficiency. Thereby, the deterioration by the heat | fever of the apparatus member installed in the reaction chamber 1a is also suppressed.

  In addition, using the above-mentioned material as a material of the 1st field of a cover does not only bring about the effect of reducing the exchange frequency of a cover, and raising the productivity of a plasma treatment apparatus. When plasma processing is performed by arranging at least a part of the induction coil 4 in the groove 3a of the dielectric member 3, the use of the above-described material as the material of the first region is advantageous in the accuracy of the plasma processing process. Has been found to be.

  Conventionally, the entire cover is generally formed of quartz. The portion ARcv facing the groove 3a is particularly susceptible to high density plasma and susceptible to plasma erosion. Therefore, if the cover is made of quartz, the quartz is eroded by the plasma, and oxygen contained in the quartz is released into the reaction chamber 1a, which affects the accuracy of the plasma processing process.

  Specifically, when quartz is eroded by plasma and oxygen in the reaction chamber 1a increases, the amount of oxygen radicals and oxygen ions in the plasma generated in the reaction chamber 1a increases, and the silicon processing speed decreases. Problems occur. Further, in the case of performing the plasma processing of the substrate 15 using a resist mask, the etching rate of the resist mask relative to the etching rate of the substrate 15 is relatively increased, which causes a problem that a desired processing shape can not be obtained. On the other hand, the use of aluminum nitride for the cover 5 suppresses the generation of oxygen, so that it is difficult for the silicon processing speed to decrease, and it becomes easier to obtain a desired processing shape, thereby improving the accuracy of the process. It has been issued.

  As shown in FIG. 1, the entire cover 5 may be formed of aluminum nitride, but aluminum nitride is expensive. On the other hand, from the viewpoint of preventing erosion of the cover 5, it is sufficient that at least ARcv of the inner surface Sa of the cover 5 is made of aluminum nitride. From the above, it is sufficient that at least the inner surface Sa of the cover 5 has the first region AR1 formed of aluminum nitride, and at least a part of ARcv only needs to be included in the first region AR1. That is, when the dielectric member 3 and the cover 5 are viewed from a direction perpendicular to the dielectric member 3, at least a part of ARcv, preferably 50% or more, more preferably 100% is within the outline of the first area AR1. As long as it is included.

  From the viewpoint of improving resistance to erosion, it is only necessary that ARcv is formed of aluminum nitride up to a depth of 10 μm or more from the surface on the stage 2 side. The thickness of the cover 5 is not particularly limited, but is usually 3 to 15 mm, preferably 5 to 12 mm, and more preferably 6 to 10 mm. When the thickness of the cover 5 is in the above range and the depth is 10 μm or more, an aluminum nitride layer having a sufficient thickness can be formed.

  In plasma processing, it is also important to suppress the adhesion of non-volatile reaction products to the dielectric member 3 and the cover 5. The non-volatile substance attached to the dielectric member 3 and the cover 5 may be peeled off during the plasma treatment process, and may float on the reaction chamber 1a and adhere to the substrate or drop onto the substrate. In addition, when the non-volatile material has conductivity, the non-volatile material attached to the dielectric member 3 and the cover 5 may inhibit the transmission of high frequency power from the induction coil to the reaction chamber. On the other hand, by forming the faraday shield (FS) in the vicinity of the dielectric member 3 and the cover 5, adhesion of the non-volatile substance to the dielectric member 3 and the cover 5 can be suppressed. In order to form the FS, it is desirable to provide an FS electrode on the opposite side of the cover 5 from the stage 2. By applying high frequency power to the dielectric member 3, the FS electrode is capacitively coupled with the plasma in the reaction chamber 1a. Thereby, FS is formed in the vicinity of the dielectric member 3 and the cover 5, and adhesion of the non-volatile substance to the dielectric member 3 and the cover 5 is suppressed.

  The surface of the dielectric member 3 on the reaction chamber 1a side can be a flat surface without unevenness. An electrode layer 19 including a predetermined electrode pattern can be easily formed on such a flat surface. Therefore, a flat plate electrode (that is, an FS electrode) for applying high frequency power to the dielectric member 3 may be formed as the electrode pattern.

  The electrode layer 19 includes, for example, an electrode pattern and an insulating film that covers the electrode pattern. The electrode pattern is formed of a conductive material. The insulating film may be formed of a dielectric material such as ceramics (for example, alumina). The insulating film suppresses metal contamination and particle generation in the reaction chamber 1a derived from the metal constituting the electrode pattern. In addition, damage to the electrode pattern due to the process gas or plasma is also suppressed. The electrode layer 19 may be a laminate of a plurality of electrode patterns and an insulating film.

  FIG. 3A is a longitudinal sectional view schematically showing the configuration of the dielectric member 3 and the electrode layer 19 according to this embodiment. In FIG. 3B, the dimensions in the vertical direction (thickness direction) of the dielectric member 3 and the electrode layer 19 are enlarged for easy understanding.

  The illustrated electrode layer 19 includes a first electrode layer 6 formed on the surface of the dielectric member 3 on the reaction chamber 1a side, and a second electrode layer formed on the surface of the first electrode layer 6 on the reaction chamber 1a side. And 7). The first electrode layer 6 includes a first electrode pattern 6 b formed directly on the surface of the dielectric member 3 and a first insulating film 6 c covering the first electrode pattern 6 b. Similarly, the second electrode layer 7 includes a second electrode pattern 7 b and a second insulating film 7 c covering the second electrode pattern 7 b. In this way, by forming at least one electrode pattern directly on the surface of the dielectric member 3 on the reaction chamber 1a side, the electrode layer 19 having a simple structure can be formed.

Hereinafter, the case where the first electrode pattern 6b is an electric heater and the second electrode pattern 7b is a flat plate electrode will be described.
In order to stabilize the process of plasma processing, it is desirable to heat the dielectric member 3 to a predetermined temperature range. For example, the temperature of the dielectric member 3 can be controlled by arranging a flat heater so as to be in contact with the entire outer surface of the dielectric member 3 with respect to the reaction chamber 1a. However, in that case, a heater is disposed between the dielectric member 3 and the induction coil 4, the distance between the plasma and the induction coil 4 is increased, and the degree of inductive coupling between the plasma and the induction coil 4 is reduced. And the plasma density decreases. On the other hand, when the electric heater 6b is provided on the surface of the dielectric member 3 on the reaction chamber 1a side, the distance between the plasma and the induction coil 4 does not increase due to the presence of the electric heater 6b. Therefore, the process can be stabilized without reducing the plasma density.

  On the other hand, FS is formed in the vicinity of the dielectric member 3 and the cover 5 by applying high frequency power to the flat plate electrode 7b. That is, a bias voltage is generated between the dielectric member 3 and the cover 5 and the plasma, and ions in the plasma act not only on the workpiece but also on the dielectric member 3 and the cover 5. Thereby, adhesion of the non-volatile substance to the dielectric member 3 and the cover 5 is suppressed.

  According to the above configuration, since the electric heater 6 b can directly heat the dielectric member 3, temperature control of the dielectric member 3 can be efficiently performed with a small amount of power. Further, since the distance between the flat plate electrode 7b and the reaction chamber 1a is short, it is possible to generate a bias voltage even when the power supplied to the flat plate electrode 7b is low, and the dielectric member 3 and the cover 5 made of a non-volatile substance. The effect of suppressing adhesion to the surface is also increased. However, the above configuration is merely an example, and a plate electrode may be directly provided as a first electrode pattern and an electric heater may be provided as a second electrode pattern on the surface of the dielectric member 3 on the reaction chamber 1a side.

  FIG. 4 shows an example of the electric heater 6b in a plan view. The electric heater 6b includes a line pattern made of a high-resistance metal. The line pattern is drawn in a serpentine shape, for example. The electric heater 6 b is connected to a heater terminal 6 a that penetrates the dielectric member 3, and the heater terminal 6 a is electrically connected to an AC power source 16. By supplying power from the AC power supply 16 to the heater terminal 6a, the first electrode pattern 6b generates heat. For example, tungsten (W) is preferably used as the high resistance metal.

  FIG. 5 shows an example of the flat plate electrode 7b in a plan view. The plate electrode 7b includes a planar pattern made of a wide metal thin film. Tungsten (W) can also be used for the plate electrode 7b. The flat plate electrode 7 b is preferably formed to cover, for example, 50% or more of the surface of the dielectric member 3 on the reaction chamber 1 a side. Thereby, most of the dielectric member 3 and the cover 5 can be shielded. In the flat plate electrode 7b, a plurality of slits 3s for transmitting high frequency power output from the first high frequency power supply 11 and the coil 4 are radially provided.

  The plate electrode 7 b is connected to an FS terminal 7 a that penetrates the dielectric member 3 in the vicinity of the center of the dielectric member 3, and the FS terminal 7 a is electrically connected to the second high-frequency power source 12. By supplying electric power from the second high frequency power supply 12 to the FS terminal 7a, a bias voltage is generated in the vicinity of the second electrode pattern 7b, and adhesion of the non-volatile substance to the dielectric member 3 and the cover 5 is suppressed.

  In FIG. 1, a first high frequency power source 11 is connected to the induction coil 4 and a second high frequency power source 12 is connected to the second electrode layer 7 (plate electrode 7b). 7b may be connected in parallel to the same high-frequency power source via a variable choke or a variable capacitor. Further, the first high frequency power supply 11 is connected to the induction coil 4, a variable choke or variable capacitor is connected to the flat plate electrode 7 b, and the power oscillated from the first high frequency power supply 11 is flat plate electrode from the coil 4 via air. The power ratio applied to the induction coil 4 and the flat plate electrode 7b may be adjusted with a variable choke or a variable capacitor by superimposing on 7b.

  When the dielectric member 3 is viewed from a direction perpendicular to the dielectric member 3, the electric heater 6b is preferably arranged so as not to protrude from the flat plate electrode 7b as shown by a broken line in FIG. Thereby, the loss of the high frequency power which permeate | transmits slit 3s can be suppressed.

  The electric heater 6 b can be formed by thermally spraying a metal of high resistance such as tungsten on the surface of the dielectric member 3 with a mask corresponding to the first electrode pattern interposed. The thickness of the thermal spray pattern is, for example, 10 to 300 μm. Alternatively, the tungsten wire may be bent into the shape of the first electrode pattern, and then the tungsten wire may be fixed to the surface of the dielectric member 3. At this time, an electrode pattern formed by using a thermal spray pattern or another method is electrically connected to the heater terminal 6a.

  The first insulating film 6c is formed, for example, by spraying white alumina on the surface of the dielectric member 3 by thermal spraying. Before thermal spraying white alumina, an adhesion layer such as yttria may be thermally sprayed on the surface of the dielectric member 3 in order to improve the adhesion between the dielectric member 3 and the first insulating film 6c. The thickness of the first electrode layer 6 is, for example, 10 to 300 μm.

  The plate electrode 7b can be formed by spraying a metal on the surface of the first electrode layer 6 with a mask corresponding to the second electrode pattern interposed. At this time, the plate electrode 7b is formed in a shape having a plurality of slits 3s arranged radially. The thickness of the flat plate electrode 7b is, for example, 10 to 300 μm. Alternatively, the plate electrode 7 b having the shape of the second electrode pattern may be formed from a metal foil or a metal plate, and then the plate electrode 7 may be fixed to the surface of the first electrode layer 6. The plate electrode 7b is disposed so as to completely cover the electric heater 6b via the first insulating film 6c, and is electrically connected to the FS terminal 7a.

  The second insulating film 7c is also formed by spraying, for example, white alumina on the surface of the first electrode layer 6 by thermal spraying. The thickness of the second electrode layer 7 is, for example, 10 to 300 μm. The method for forming the first and second insulating films is not particularly limited. For example, the first and second insulating films may be formed by sputtering, chemical vapor deposition (CVD), vapor deposition, coating, or the like.

  Hereinafter, an example of the operation of the dry etching apparatus 10 of the present embodiment will be described. First, the object to be treated is carried out from the gate provided in the container 1, and the object to be treated is supported by the stage installed in the reaction chamber 1a. Thereafter, the inside of the reaction chamber 1a is exhausted. The inside of the reaction chamber 1a is a reduced pressure atmosphere, and a pressure substantially equal to the atmospheric pressure is applied to the dielectric member 3. The dielectric member 3 has a groove 3a, and a portion corresponding to the groove 3a is thin. However, since the grooves 3a are annularly formed so that the mechanical strength is sufficiently maintained, the dielectric member 3 is not broken.

Thereafter, a process gas is introduced into the reaction chamber 1 a from the predetermined gas supply source via the gas inlet 8. The substrate 15 to be etched has a resist mask corresponding to the etching pattern. When the substrate 15 is, for example, Si, for example, a fluorine-based gas (SF ₆ or the like) is used as a process gas. When the substrate 15 is aluminum, for example, a chlorine-based gas (such as HCl) is used as a process gas.

  Next, high frequency power is supplied from the first high frequency power supply 11 to the induction coil 4, and plasma is generated in the reaction chamber 1a. At this time, a bias voltage is applied to the stage 2 holding the substrate 15 from a predetermined high frequency power supply. As a result, radicals and ions in the plasma are transported to the surface of the substrate 15, accelerated by the bias voltage, and collide with the substrate 15. As a result, the substrate 15 is etched.

  Here, of the conductor 4 a forming the induction coil 4, the outer peripheral side portion having a high coil density is disposed in an annular groove 3 a formed in the dielectric member 3. Therefore, by applying relatively small electric power, a donut-shaped high-density plasma is generated in the vicinity of the dielectric member 3 on the reaction chamber 1a side, and this reaches the substrate 15 as diffusion plasma.

  On the other hand, power is supplied from the second high-frequency power source 12 to the plate electrode 7b disposed on the surface of the dielectric member 3 on the reaction chamber 1a side, and a bias voltage is generated in the vicinity of the plate electrode in the reaction chamber 1a. Thereby, some of the ions in the plasma are accelerated by the bias voltage and enter the dielectric member 3 (or the electrode layer 19) and the cover 5. As a result, the adhesion of the nonvolatile material to the dielectric member 3 (or the electrode layer 19) and the cover 5 is suppressed.

  The etching process is continuously performed on a plurality of substrates 15. Therefore, in order to ensure process stability, electric power is supplied from the AC power supply 16 to the electric heater 6b provided on the surface of the dielectric member 3 on the reaction chamber 1a side, and temperature management is performed by heating the dielectric member 3. It will be.

Second Embodiment
The plasma processing apparatus according to the present embodiment is the same as the first embodiment except that the structure of the cover is different. FIG. 6 shows the configuration of a dry etching apparatus 10A provided with a cover 5A according to the present embodiment. The same code | symbol is attached | subjected to each element of this embodiment corresponding to each element of 1st Embodiment.

  When at least a part of the induction coil 4 is disposed in the groove 3a of the dielectric member 3 and the plasma generation part is localized directly under the groove 3a (that is, directly under ARcv), in other parts, the process gas The efficiency of dissociation to radicals decreases. Accordingly, it is desirable that the gas outlet 9 for jetting the process gas into the reaction chamber 1a is selectively formed within the range of ARcv of the cover 5A. For example, it is preferable that 50% or more of the gas jets 9 be formed in the ARcv on a number basis, and it is preferable that all the gas jets 9 be formed in the ARcv.

  In the case of the illustrated example, the shape of ARcv is also annular corresponding to the annular groove 3a. Therefore, it is preferable that all the gas outlets 9 are provided concentrically so that the gas outlets 9 are included in the annular ARcv. On the other hand, it is preferable not to form the gas outlet 9 in the central region surrounded by ARcv. As a result, more process gas is supplied immediately below ARcv in which the plasma generation portion is localized, as compared to the other spaces. Therefore, the separation efficiency of the process gas to radicals is improved.

  The shape of the gas jet nozzle 9 is not particularly limited, and may be, for example, a circle, an ellipse, a rectangle, or a rectangle with rounded corners. Especially, it is preferable that it is circular at the point which is easy to form. The diameter (maximum diameter in the case of other than a circle) of the gas jetting port 9 is not particularly limited, but is preferably 0.1 to 1.5 mm in that it is easy to form and has excellent material gas supply performance. The thickness is more preferably 0.3 to 1.0 mm, and particularly preferably 0.5 to 0.8 mm.

From the viewpoint of increasing the residence time of the process gas directly under ARcv where the plasma generating portion is localized, the number of gas jets 9 formed per unit area of ARcv is increased as compared with the conventional case. It is desirable to suppress the gas flow rate per nozzle 9. For example, it is preferable to provide 0.1 to 10 gas jet holes 9 per 1 cm ² of unit area of ARcv.

  More specifically, when the gas jets 9 are circular and the diameter is 0.1 to 1.5 mm, the number of gas jets 9 formed in the cover 5A is about 48 to 60. Is preferred. Also, from the viewpoint of supplying a sufficient amount of process gas from the gas jet 9 into the reaction chamber 1a, the total area of the gas jet 9 is about 0.5 to 5% of the area of the inner surface Sa of the cover 5A. Is preferred.

  From the viewpoint of prolonging the residence time of the process gas immediately below ARcv, the end of the gas injection port 9 on the reaction chamber 1a side, that is, the outlet of the gas may be extended in a dipper shape. Thereby, the advancing direction of the process gas immediately after ejection is dispersed in the horizontal direction, and the flow velocity in the vertical direction is suppressed. The area of the tapered outlet of the gas outlet 9 is preferably about 1.1 to 5 times the cross-sectional area perpendicular to the gas flow in the narrowest part of the gas outlet 9.

Third Embodiment
The plasma processing apparatus according to the present embodiment is the same as the first embodiment except that the structure of the cover is different. FIG. 7 shows the configuration of a dry etching apparatus 10B provided with a cover 5B according to the present embodiment. The same code | symbol is attached | subjected to each element of this embodiment corresponding to each element of 1st Embodiment.

  The cover 5B includes a first portion 5a formed of aluminum nitride and a second portion 5b formed of other dielectric material (for example, alumina). The 1st part 5a is disk shape, and the 2nd part 5b is a frame-shaped body which supports the peripheral part of the 1st part 5a. That is, the inner surface Sa of the cover 5B has not only the first area AR1 formed of aluminum nitride but also a second area corresponding to the second portion. This makes it possible to make the first portion 5a to be formed of aluminum nitride relatively small. In addition, considerable cost is required to form a plate member having a large diameter with expensive aluminum nitride.

  Inside the second portion 5b, an edge portion T that abuts on the peripheral portion of the first portion 5a is provided. The first portion 5a is fixed to the second portion 5b by the peripheral portion of the first portion 5a being pinched by the edge T of the second portion 5b and the pressing plate 20 which can be attached to and detached from the second portion 5b. Be done. The first portion 5a is detachable with respect to the second portion 5b (ie, the first area AR1 is detachable with respect to the second region), and the first portion 5a can be obtained by removing the pressing plate 20 from the second portion 5b. Can be separated from the second portion 5b. As a result, it is possible to replace only the first area AR1 in the cover 5B as necessary. Thus, maintenance costs can be reduced.

  The second region surrounding the outer periphery of the first region AR1 is a region where the plasma density is relatively small and the plasma is less susceptible to erosion, like the central region surrounded by ARcv. Further, ARcv facing the groove 3a is included in the first area AR1. Therefore, even when the second portion 5b is formed of quartz or alumina, for example, the same merit as in the case of forming the entire cover 5B of aluminum nitride can be enjoyed. On the other hand, the cost required for the cover 5B is reduced.

Next, an experiment was conducted to verify the superiority in the case of using a dielectric member having a groove according to the present invention.
First, as shown in FIG. 8, as the shape of the dielectric member 3, the structure 1 (conventional flat plate type), the structure 2 (structure having the conventional beam 3b), and the structure 3 (groove according to one embodiment of the present invention) are used. Three types of structures having 3a were prepared. Then, these three types of dielectric members were attached to the plasma processing apparatus, and evaluations of the respective discharge stable regions were performed.

  The evaluation results of the discharge stable region of each structure are shown in FIGS. In either case, the horizontal axis represents pressure, and the vertical axis represents electric power supplied to the induction coil. In FIGS. 9A, 9 C, and 9 E, when dielectric members of structures 1 to 3 are used, a region where discharge can be obtained is indicated by ○, and a region where discharge is not obtained is indicated by x. ing. FIGS. 9B, 9D, and 9F show the coil voltages generated at both ends of the induction coil when the high frequency power is applied when the dielectric members having the structures 1 to 3 are used, respectively. It is a measurement result. Depending on the voltage value, A (> 10000 V), B (8000-10000 V), C (6000-8000 V), D (4000-6000 V), E (2000-4000 V), F (<2000 V) and ranked It shows.

  In structure 1, as shown in FIG. 9A, plasma could be generated in a wide region. However, as shown in FIG. 9 (b), when the power supplied to the induction coil was increased, the coil voltage tended to increase. This indicates that the coupling between the induction coil and the plasma is weak and the power loss is large. Therefore, it is not easy to efficiently contribute the electric power supplied to the induction coil to the discharge, and high speed processing is difficult.

  In the structure 2, as shown in FIG. 9C, stable plasma discharge can be maintained in the low pressure region, but stable discharge can not be obtained on the high pressure side. In order to investigate this cause, the light emission state of the plasma was observed. As a result, in the low pressure region, the plasma generated in the region (recess formed by the beam structure) in the reaction chamber immediately below the induction coil crosses the protrusion formed by the beam structure and is connected in a donut shape. I found out. On the other hand, it was found that in the high pressure region, the plasma was unevenly distributed inside the recess formed by the beam-like structure. In the high pressure region, the unevenness formed on the reaction chamber side surface of the dielectric member due to the beam-like structure inhibits the diffusion of the plasma generated immediately below the induction coil in the lateral direction, so the plasma is unevenly distributed, It is considered that the coupling between the induction coil and the plasma is destabilized. Thus, in the case of the structure 2, it is difficult to obtain a wide discharge stable region.

  In the structure 3, as shown in FIG. 9 (e), stable plasma discharge was able to be maintained in the entire region where the experiment was performed. Further, as shown in FIG. 9 (f), the coil voltage was lower in all the regions where the experiment was performed compared to the structure 1 and the structure 2. That is, by thinning a part of the dielectric member, the coupling between the induction coil and the plasma is strengthened, and the reduction of the power loss can be realized. Moreover, in the structure 3, since the surface of the dielectric member on the reaction chamber side can be made flat, a uniform plasma can be stably maintained over a wide region. Therefore, it is possible to develop into various processes with different gas types and pressure regions.

  Furthermore, the performance of plasma dicing was evaluated. Plasma dicing is a method of dividing individual device layers by masking individual device layers with a photoresist (PR) or a protective film and processing an open street portion in the vertical direction by plasma. By adjusting and combining the processing conditions, individualization according to the required specifications for each device can be realized. Moreover, since the smooth side surface shape can be obtained compared with the existing construction method, the bending strength of the singulated chip is improved. In the case of plasma dicing a silicon substrate, vertical processing is usually performed by a process called silicon process alternately repeating a silicon etching step and a polymer deposition step.

  First, silicon processing speed and polymer deposition speed were evaluated when Structure 1 and Structure 3 were used as dielectric members. For Structure 1, the optimized silicon processing rate was 20 μm / min and the polymer deposition rate was 0.5 μm / min. Also, for Structure 3, the optimized silicon processing rate was 30 μm / min and the polymer deposition rate was 1.0 μm / min. That is, by using the structure 3 as the dielectric member, it is possible to obtain a processing or deposition rate of 1.5 to 2 times that of the conventional one.

  Next, plasma dicing of silicon was performed using optimized silicon etching conditions and polymer deposition conditions. As an evaluation sample, a silicon substrate having a resist mask thickness of 7 μm, a street width of 20 μm, a mask aperture ratio of 1.0%, and a diameter of 200 mm was used. By alternately repeating the above-described silicon etching step with a silicon processing rate of 30 μm / min and polymer deposition step with a polymer deposition rate of 1.0 μm / min, silicon exposed to the mask opening could be processed vertically. . At this time, the silicon dicing speed was 22 μm / min, the in-plane uniformity was ± 3.0%, and high-speed and high-uniform processing characteristics were obtained.

  The plasma processing apparatus of the present invention is useful in processes requiring simple maintenance and high-density plasma, and can be applied to various plasma processing apparatuses including a dry etching processing apparatus and a plasma CVD apparatus.

  1: container, 1a: reaction chamber, 2: stage, 3: dielectric member, 3a: groove, 3x: first groove, 3y: second groove, 3s: slit, 4: induction coil, 4a: conductor, 5: Cover, 6: first electrode layer, 6a: heater terminal, 6b: first electrode pattern (electric heater), 6c: first insulating film, 7: second electrode layer, 7a: FS terminal, 7b: second electrode pattern (Flat plate electrode (FS electrode)) 7c: second insulating film 8: gas inlet 8a: gap 9: gas jet 10: dry etching apparatus 11: first high frequency power supply 12: second high frequency Power supply 13: first elastic ring 14: second elastic ring 15: substrate 16: AC power supply 17: first holder 18: second holder 19: electrode layer 20: pressure plate

Claims (5)

A container having a reaction chamber,
A stage for supporting an object in the reaction chamber;
A dielectric member that closes the opening of the container and faces the stage;
A cover installed to cover the dielectric member in the reaction chamber;
An induction coil disposed outside the reaction chamber of the dielectric member and generating plasma in the reaction chamber;
An annular groove is formed on the outer surface of the dielectric member with respect to the reaction chamber,
At least a portion of the induction coil is disposed in the groove;
Surface prior Symbol stage side of said cover, said region where the groove of the dielectric member is formed with a first region covering the area of the inner, and a second region of the annular surrounding the first region, the Have
The first region is formed of aluminum nitride,
The plasma processing apparatus , wherein the second region is formed of a dielectric material other than aluminum nitride . Before Stories second region is formed of quartz or alumina, a plasma processing apparatus according to claim 1. Wherein the first region, to the second region, is removable, the plasma processing apparatus according to claim 1 or 2. The plasma processing apparatus of any one of Claims 1-3 further provided with the Faraday shield electrode installed in the surface by the side of the said reaction chamber of the said dielectric material member . (I) a process of supporting an object to be processed on a stage installed in a reaction chamber;
(Ii) applying high frequency power to an induction coil installed outside a dielectric member partitioning the reaction chamber to generate plasma in the reaction chamber, and plasma-treating the object to be processed. ,
A cover is provided in the reaction chamber to cover the dielectric member,
An annular groove is formed on the outer surface of the dielectric member with respect to the reaction chamber,
At least a portion of the induction coil is disposed in the groove;
Surface prior Symbol stage side of said cover, said region where the groove of the dielectric member is formed with a first region covering the area of the inner, and a second region of the annular surrounding the first region, the Have
The first region is formed of aluminum nitride,
The second region is formed of a dielectric material other than aluminum nitride .

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