JP2017107864A - Plasma processing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing apparatus performing stable plasma production in wide-area process conditions and having processing performance excellent in uniformity and reproducibility.SOLUTION: In a plasma processing apparatus including an upper electrode 3 having a gas supply hole 6, gas supply means, and a lower electrode 1, the gas supply means includes a flat member 4 having a gas hole 8 and a flat member 5 having a gas hole 10, the gas supply hole 6 and the gas hole 8 are connected via a groove 7 and the gas hole 8 and the gas hole 10 are connected via a groove 9, and the gas supply hole 6, the gas hole 8, and the gas hole 10 are arranged at positions different mutually in a plane.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a plasma processing apparatus.

  In plasma processing represented by dry etching, a raw material gas is introduced into a vacuum vessel having a vacuum exhaust means, and the raw material gas is converted into plasma by electromagnetic waves and exposed to the sample to be processed, except for the mask portion on the surface of the sample to be processed. This is a semiconductor microfabrication process to obtain a desired shape by etching. The processing uniformity within the surface of the sample to be processed is affected by the plasma distribution, the temperature distribution within the surface of the sample to be processed, the composition of the supply gas, the flow rate distribution, and the like. In particular, in the parallel plate type plasma processing apparatus disclosed in Patent Document 1, a raw material gas is supplied from a shower plate in which a large number of fine gas discharge holes arranged on the surface of the sample to be processed are formed. Since the distance between the shower plates is also relatively short, the gas supply distribution supplied from the shower plates affects the processing speed, the processing shape, and the like. The parallel plate type plasma processing apparatus has an advantage that the desired uniformity can be obtained by utilizing this characteristic to control the distribution of the processing speed and shape in the sample surface to be processed.

  However, in the parallel plate type plasma processing apparatus, there is a strong high-frequency electric field for forming plasma in the vicinity of the shower plate, and discharge may occur in the gas holes formed in the shower plate due to the electric field. The discharge in the gas hole causes the generation of foreign matter or contamination from a conductive member or the like disposed on the back surface of the shower plate. In addition, the machining shape at the sample surface position corresponding to the discharge location in the gas hole is also affected, which may cause defects. Further, when discharge occurs in the gas holes, the amount of consumption of the shower plate holes is increased, and there is a problem that the replacement period of the shower plate is shortened and the manufacturing cost is increased.

  In order to cope with the above-described problems, the diameter of the gas hole normally applied to the shower plate is made as small as possible. For example, by using gas holes of 0.1 mm to 0.5 mm, it is possible to increase the probability of annihilation of electrons on the side walls of the holes and reduce the discharge risk in the gas holes. However, simply reducing the diameter of the gas hole does not essentially prevent discharge in the gas hole, but restricts discharge conditions (such as restrictions on discharge power and discharge gas flow rate). Further, if the gas holes are made smaller in diameter, the processing cost of the shower plate becomes higher, which increases the cost. Furthermore, it is usually necessary to match the gas hole on the conductor located on the back of the shower plate with the gas hole position on the shower plate for uniform gas discharge. However, it is difficult to achieve accuracy, and in-plane uniformity of gas emission may be reduced, or reproducibility of gas emission may not be obtained.

  Further, in Patent Document 1, in order to suppress abnormal discharge generated in the gas holes of the shower plate, the upper electrode is disposed on the shower plate provided with the first gas holes and on the back surface of the shower plate. An antenna base material having a conductor plate provided with gas holes, an insulating plate provided at the center of the conductor plate and provided with a third gas hole, and a temperature control function and a gas dispersion portion provided on the back surface of the conductor plate A first minute gap in the radial direction at the interface between the shower plate and the insulating plate, and a second minute gap in the radial direction at the interface between the insulating plate and the conductor plate. A plasma processing apparatus is disclosed in which the centers of the gas hole and the third gas hole are shifted in the circumferential direction or the radial direction.

  However, in this apparatus, although it is possible to suppress abnormal discharge at the central portion of the conductor plate, abnormal discharge suppression other than at the central portion is not considered. Further, although the first gas hole and the third gas hole are deviated, sufficient consideration is given to the lack of conductance of the gas flow due to the deviation of the first gas hole and the third gas hole. Absent.

  As a result of the above, in the conventional shower plate structure, there are cases where the processing performance by the plasma cannot be sufficiently brought out due to the limitation of the etching conditions, the uniformity and the reproducibility.

JP 2011-9249 A

  The present invention aims to improve the uniformity and reproducibility of gas emission in the plasma processing apparatus described in the “Background Art”, and is further limited by the occurrence of abnormal discharge in the gas supply means, foreign matters and contamination resulting therefrom. The present invention is intended to realize a plasma processing apparatus having a gas supply means that can significantly reduce the discharge conditions (discharge power and discharge gas flow rate), and an object of the present invention is a parallel plate type plasma processing apparatus. Even so, an object of the present invention is to provide a plasma processing apparatus having stable plasma generation under a wide range of process conditions and processing performance excellent in uniformity and reproducibility.

As an embodiment for achieving the above object, a processing chamber in which a sample is plasma-processed and a gas supply unit to which a high-frequency power for generating plasma is supplied and a gas for generating the plasma is supplied are formed. In a plasma processing apparatus comprising: the first electrode that has been made; and a second electrode that faces the first electrode and on which the sample is placed;
A gas is supplied from a plurality of first gas holes penetrating the gas supply part, and a first gas supply plate disposed below the first electrode and a plurality of second gas passing through the first gas supply plate. A second gas supply plate that is supplied with gas from the second gas hole and disposed below the first gas supply plate;
The second gas supply plate has a plurality of third gas holes penetrating through the inside and supplies the gas supplied from the second gas hole into the processing chamber from the third gas hole,
The first gas hole and the second gas hole are connected to any of a plurality of ring-shaped first gas flow paths having different radii,
The second gas hole and the third gas hole are connected to any of a plurality of ring-shaped second gas flow paths having different radii,
The first flow path is formed in the gas supply unit or the first gas supply plate,
The second flow path is formed in the second gas supply plate or the first gas supply plate disposed above the second electrode,
The first gas flow path in the plan view and the second gas flow path in the plan view overlap,
The first gas hole is located in the gas supply section so that the first gas hole in the plan view of the second gas supply plate is located next to one of the third gas holes in the plan view. Formed,
The second gas hole is formed in the first gas supply plate so that the second gas hole in the plan view is located next to the other of the third gas hole in the plan view. A plasma processing apparatus characterized by the above.

A first electrode having a processing chamber in which the sample is plasma-treated, a gas supply unit to which a high-frequency power for generating plasma is supplied and a gas for generating the plasma is supplied; In a plasma processing apparatus comprising a second electrode facing the one electrode and mounting the sample,
A gas is supplied from a plurality of first gas holes penetrating the gas supply part, and a first gas supply plate disposed below the first electrode and a plurality of second gas passing through the first gas supply plate. A second gas supply plate that is supplied with gas from the second gas hole and disposed below the first gas supply plate;
The second gas supply plate has a plurality of third gas holes penetrating through the inside and supplies the gas supplied from the second gas hole into the processing chamber from the third gas hole,
The first gas hole and the second gas hole are connected to any of a plurality of ring-shaped first gas flow paths having different radii,
The second gas hole and the third gas hole are connected to any of a plurality of ring-shaped second gas flow paths having different radii,
The first flow path is formed in the gas supply unit or the first gas supply plate,
The second flow path is formed in the second gas supply plate or the first gas supply plate disposed above the second electrode,
The position of the first gas hole in the plan view of the second gas supply plate is different from the position of the second gas hole in the plan view and the position of the third gas hole in the plan view. Gas holes are formed in the gas supply unit,
The second gas hole is formed in the first gas supply plate so that the position of the second gas hole in the plan view is different from the position of the third gas hole in the plan view. The plasma processing apparatus is characterized.

  ADVANTAGE OF THE INVENTION According to this invention, even if it is a parallel plate type plasma processing apparatus, the plasma processing apparatus which has the processing performance excellent in the stable plasma production | generation in a wide range of process conditions and the uniformity and reproducibility can be provided. .

1 is a cross-sectional view of a basic configuration of a plasma processing apparatus according to a first embodiment of the present invention. FIG. 2 is a schematic structural cross-sectional view of a gas supply unit shown by A in FIG. 1. It is the schematic structure top view which looked at the gas supply means part in the plasma processing apparatus shown in FIG. 1 from the lower side (lower electrode side), an upper side shows the whole figure, and the lower side shows the partial enlarged view. It is schematic structure sectional drawing of the principal part (shower plate and upper electrode) for demonstrating the subject in the conventional plasma processing apparatus. 4 is a cross-sectional view of the upper electrode for explaining the ease of occurrence of abnormal discharge due to the opening diameter in the main part shown in FIG. 4, the left side has a large opening diameter, the center has an opening diameter in the middle, the right side has The case where the opening diameter is small is shown. It is a figure for demonstrating the relationship between a discharge start voltage and pd product (product of the pressure of atmospheric gas, and the distance between electrodes).

  In one embodiment of the present invention, the upper electrode arranged at a position facing the sample to be processed is provided with a planar gas supply means, the gas supply means is composed of two layers of the same diameter member, and each member of each layer And a gas supply structure in which a plurality of gas discharge holes are provided, and the gas holes of each layer are fluidly connected by a groove-like gas connection structure formed in a planar direction. Thereby, it becomes possible to arrange | position so that the gas hole formed in the member of each layer may not correspond planarly.

  According to the present invention, uniform and stable gas supply to the sample surface to be processed can be realized with good reproducibility, and further, discharge conditions restricted by abnormal discharge generated in the gas supply means can be greatly relaxed, so that a wide range is provided. A plasma processing apparatus capable of processing under process conditions can be provided.

  Hereinafter, the present invention will be described using examples.

  A first embodiment of the present invention will be described with reference to FIG. FIG. 1 shows a cross-sectional view of a basic configuration of a plasma processing apparatus in the present embodiment. First, the apparatus configuration in FIG. 1 will be described. FIG. 1 shows a parallel plate type plasma processing apparatus, in which an upper electrode 3 and an upper electrode 3 arranged at positions opposed to a sample to be processed (wafer) 2 arranged on a sample setting means (sample stage) 1 are shown. A first planar member 4 and a second planar member 5 having the same diameter as gas supply means are arranged on the workpiece 2 side. Gas supply to the first planar member 4 and the second planar member 5 is performed from a gas supply unit 6 formed on the upper electrode 3 which is usually made of aluminum or stainless steel. The first and second planar members do not have to have the same diameter, but it is more practical to have the same diameter.

  Next, a gas supply means part is demonstrated using FIG. 2 and FIG. 2 is a schematic cross-sectional view of the gas supply means in the plasma processing apparatus shown in FIG. 1, and FIG. 3 is a schematic plan view of the gas supply unit 6, the first planar member 4 and the second electrode of the upper electrode 3. The detailed drawing of the planar member 5 part of is shown. FIG. 2 is a detailed view of the dotted line portion A of FIG. 1, and is a cross-sectional view of the gas supply portion 6 of the upper electrode 3, the gas holes 8 of the first planar member 4, and the gas holes 10 of the second planar member 5 portion. Indicates. The gas hole 6, the gas hole 8, and the gas hole 10 are arranged so as to be shifted in a plane. The gas hole 6 and the gas hole 8 are arranged via the first groove 7, and the gas hole 8 and the gas hole 10 are Two grooves 9 are connected. This configuration will be described with reference to FIG.

  FIG. 3 is a plan view of the second planar member 5 viewed from the workpiece 2 side. The plasma source gas is supplied from the gas supply portion 6 formed in the upper electrode 3 formed of a conductor through the first groove 7 formed in the circumferential direction to the gas hole 8 of the first planar member 4. Led to. The gas that has passed through the gas holes 8 of the first planar member 4 passes through the second groove 9 formed in the circumferential direction so as to overlap the first groove in a planar manner. The gas hole 10 is guided to the discharge space 11 and finally introduced into the discharge space 11. As shown in FIG. 3, the gas supply part 6 (gas hole shown by the dotted line in FIG. 3) formed in the upper electrode 3 and the gas hole 8 (the thin solid line in FIG. 3) of the first planar member 4. The gas holes shown in Fig. 2 have structures formed respectively at locations that do not coincide with each other in plan view. Similarly, the gas hole 8 (gas hole shown by a thin solid line in FIG. 3) of the first planar member 4 and the gas hole 10 (shown by a thick solid line in FIG. 3) of the second planar member 5. The gas holes are also formed at positions that do not coincide with each other in a plane. Note that the first groove and the second groove do not have to be formed so as to overlap in a planar manner, but it is easier to manufacture the first groove and the second groove with a simple structure.

  In this embodiment, quartz is used for the first planar member 4 and the second planar member 5. Moreover, the 1st groove | channel 7 and the 2nd groove | channel 9 which are shown by FIG. 2 were each formed in both surfaces of the 1st planar member. The gas supply means does not necessarily need to be composed of two planar members, but it is more practical to construct the gas supply means because two grooves are easily formed. Further, the first groove 7 and the second groove 9 do not need to be provided in the first planar member 4 and can be formed in the upper electrode or the second planar member. It is practical and easy to process on both sides. The diameters of the gas holes 8 of the first planar member 4 and the gas holes 10 of the second planar member 5 shown in FIGS. 1, 2, and 3 were 0.4 to 0.5 mm. The thickness of each planar member was 15 mm. In FIG. 2, the first groove 7 and the second groove have a groove width (space width in the plane direction) of 3 mm and a groove height of 0.3 mm. In this embodiment, the gas holes 10 of the second planar member 5, the gas holes 8 of the first planar member 4, and the gas supply portions 6 formed in the upper electrode 3 are arranged concentrically, and the second The number of gas holes of the gas supply part 6 formed in the gas hole 8 of the first planar member 4 and the upper electrode 3 was halved with respect to the number of gas holes 10 of the planar member 5. Specifically, the number of gas holes 10 in the second planar member 5 is 750, and the number of gas holes in the gas supply portion 6 formed in the gas holes 8 and the upper electrode 3 of the first planar member 4 is 375. It was. 1, the high frequency power from the high frequency power source 13 is supplied to the upper electrode 3 through the matching unit 12, and the high frequency power and the magnetic force generated by the solenoid coil 15 disposed outside the vacuum vessel 14 are used. Thus, the plasma 16 is formed in the discharge space 11 by the above interaction. A high-frequency power source 17 different from that for plasma generation is connected to the workpiece sample placement means 1 for placing the workpiece sample 2 via a matching unit 18. The high frequency power from the high frequency power source 17 has a function of accelerating ions from the plasma 16 and irradiating the sample 2 to be processed. Further, a cooling means 19 is connected to the workpiece sample setting means 1 and has a function of adjusting the temperature of the workpiece sample 2. In the embodiment of FIG. 1, the frequency of the high-frequency power supplied to the upper electrode 3 is 200 MHz, and the frequency of the high-frequency power supplied to the workpiece sample setting means 1 is 4 MHz. Reference numeral 24 denotes an upper electrode temperature control means.

  Next, problems in the conventional apparatus to be solved by the present invention will be described with reference to FIG. FIG. 4 is a schematic cross-sectional view of a general gas supply structure applied to the upper electrode of the parallel plate apparatus, and shows an enlarged view near the gas discharge hole. Usually, a plurality of gas holes shown in FIG. 4 are arranged in the plane direction. In the conventional apparatus of FIG. 4, the gas hole 23 of the shower plate 22 is formed in the same position as the gas supply part 21 formed in the upper electrode 20 formed of a conductor.

  In order to perform stable gas discharge into the discharge space with the structure of FIG. 4, it is necessary to arrange the gas supply part 21 formed in the upper electrode 20 and the gas hole 23 of the shower plate 22 in alignment. At this time, if the size of the gas supply part 21 formed in the upper electrode 20 is about the same size as the gas hole 23 of the shower plate 22, a difference in the amount of gas emission may occur for each hole due to the displacement of the hole position. The situation changes with each installation, and the uniformity and reproducibility of gas emission cannot be obtained. Further, due to thermal expansion accompanying a temperature rise during use, the relative position of the gas supply part 21 formed in the gas hole 23 of the shower plate 22 and the upper electrode 20 changes, and the state of gas emission changes over time. It may occur. Since the shower plate 22 is usually a replacement part, it needs to be attached to and detached from the upper electrode 20, and high attachment accuracy is required to ensure that the gas holes coincide with each other.

  However, since it is difficult to make the gas holes coincide with each other only with accuracy, the size of the gas supply part 21 applied to the upper electrode 20 is made larger than the gas hole diameter of the shower plate 22 as shown in FIG. Even if some hole displacement occurs, the gas holes are prevented from being completely displaced. However, in this structure, it is necessary to considerably expand the hole diameter of the gas supply unit 21 applied to the upper electrode 20, and the risk of causing abnormal discharge in the hole of the gas supply unit 21 increases. In particular, in the structure of FIG. 4, since active particles such as electrons directly enter the hole of the gas supply unit 21 from the plasma through the gas hole 23 of the shower plate 22, the discharge is performed in addition to the size of the space. As a result, the active particles are mixed, and abnormal discharge is more likely to occur. Therefore, in order to prevent abnormal discharge, it is necessary to limit the high-frequency power applied to the upper electrode 20 and the gas flow rate emitted from the gas supply unit 21, which restricts the process performance.

  In the structure of FIG. 4, the surface of the upper electrode 20 formed of a normal conductor is disposed at a position where it can be directly seen from the plasma through the gas hole 23 of the shower plate 22. As described above, since electrons and active particles enter from the gas holes of the shower plate 22 from the plasma, the surface of the upper electrode, which is a conductor, is affected, and metal contamination and generation of foreign matter may occur. . Although measures such as coating the surface of the upper electrode 20 with a stable material are possible, the coating deteriorates or peels off depending on the usage time. Replacement is required, resulting in an increase in running costs and a reduction in equipment operation rate.

  With respect to the problem described with reference to FIG. 4, the operation and effect of the plasma processing apparatus according to the present embodiment described with reference to FIGS. 1, 2, and 3 will be described. As shown in FIG. 2, the first planar member 4 has a first groove 7 formed on the upper electrode 3 side, and gas is supplied from the gas supply unit 6 formed in the upper electrode 3 to the groove. . The gas supplied to the first groove 7 flows in the plane direction of the first groove 7, and flows to the second groove 9 via the gas hole 8 arranged at a position different from the gas supply unit 6 in a plane. . Subsequently, the gas flows in the plane direction of the second groove 9 and is discharged into the discharge space 11 from the gas hole 10 arranged at a position different from the gas hole 8 in a plane. From the gas flow, the gas supply section 6 formed in the upper electrode 3, the gas holes 8 of the first planar member 4, and the gas holes 10 of the second planar member 5 are grooves that are sufficiently wide with respect to each hole diameter. Since the fluid is connected via the first groove 7 and the second groove 9 having a width, there is no occurrence of a hole shift in the connecting portion of the gas supply, which is a problem in the conventional apparatus configuration of FIG. As a result, stable and highly reproducible gas release characteristics can be maintained. For the above reasons, the hole diameter of the gas supply unit 6 formed in the upper electrode 3 can be minimized, and abnormal discharge of the gas supply unit 6 formed in the upper electrode 3 can be suppressed.

  Next, the reason why abnormal discharge is less likely to occur as the hole diameter of the gas supply unit 6 is smaller will be described with reference to FIG. FIG. 5 is a detailed view of the gas supply unit 21 formed on the upper electrode 20 of FIG. 4 and shows the equipotential surface depending on the diameter of the gas supply unit 21. When the opening diameter of the gas supply unit 21 is large, the equipotential surface 25 due to the electric field of the high frequency power applied to the upper electrode 20 penetrates into the hole (the electric field penetrates into the hole). As a result, an electric field 26 is generated in the hole of the gas supply unit 21, and the electric field 26 tends to cause a discharge in the gas supply unit 21. As shown in FIG. 5, the equipotential surface 25 that penetrates into the gas supply unit 21 is reduced when the opening diameter of the gas supply unit 21 is reduced, and at the same time, the electric field 26 generated in the gas supply unit 21 is also eliminated. Thereby, the risk of abnormal discharge can be reduced as the hole diameter of the gas supply unit 21 is smaller.

  The ease of occurrence of abnormal discharge in the gas supply unit 21 can also be explained from Paschen's law shown in FIG. The ease with which discharge occurs depends on the product of the size of the space and the gas pressure in that region. FIG. 6 shows the discharge start voltage in various gases with respect to the product (pd product) of the gas pressure p and the space size d, and shows that the higher the discharge start voltage, the less likely the discharge occurs. The abnormal discharge of the gas supply unit 6 occurs near the interface between the upper electrode 3 and the first planar member 4. Usually, the gas pressure near the interface between the upper electrode 3 and the first planar member 4 is 10 to 15 Torr. Therefore, from FIG. 6, when the gas pressure is 15 Torr, the discharge start voltage becomes high and the abnormal discharge is unlikely to occur when the hole diameter of the gas supply section 6 serving as the discharge space is 1 mm or less. The explanation in FIGS. 5 and 6 shows the tendency to the last, and the discharge space influences not only the hole diameter but also the hole depth direction to some extent. Therefore, in practice, the margin for suppressing the occurrence of abnormal discharge can be expanded by setting the hole diameter to be smaller than 1 mm. Actually, in this embodiment, the hole diameter of the gas supply unit 6 is set to 0.5 mm. As a result, the occurrence of abnormal discharge in the gas supply unit 6 is greatly suppressed, and a structure that facilitates the passage of gas is realized.

  Furthermore, in the plasma processing apparatus according to the present embodiment described with reference to FIGS. 2 and 3, the member that can be directly seen from the discharge space 11 through the gas hole 10 of the second planar member 5 that functions as a shower plate is the first member. 1 is a planar member 4, and active particles from the plasma 16 do not reach the upper electrode 3 (electrons and excited active particles are formed in the gas holes 10 of the second planar member 5, the second In the process of passing through the groove 9 and the gas hole 8 of the first planar member 4, it disappears or de-excites due to collision with gas molecules or the side wall of the passing member, so that it cannot reach the surface of the upper electrode 3). As a result, by forming the first planar member 4 and the second planar member 5 with a material such as quartz, it is possible to prevent metal contamination and foreign matter from the upper electrode member formed of a metal that is a conductor. From the viewpoint of metal contamination, it is particularly effective when the plasma is corrosive.

Next, the first groove 7 and the second groove 9 in FIGS. 1, 2 and 3 will be described. In this example, the first groove 7 and the second groove 9 were formed on the front and back of the first planar member 4, and the groove width was 3 mm and the groove height was 0.3 mm. The first groove 7 and the second groove 9 were formed so as to connect gas holes arranged concentrically with the same diameter as shown in FIG. In the configuration shown in FIG. 3, the pitch in the radial direction of the gas holes arranged concentrically is 10 mm (distance between the gas holes in the radial direction). Therefore, the groove widths of the first groove 7 and the second groove 9 are set to 3 mm (gas shielding width 7 mm between each diameter) as a width that can sufficiently separate the gas holes arranged in each diameter. The groove height of the first groove 7 and the second groove 9 is set to 0.3 mm for the purpose of suppressing abnormal discharge in the grooves. The electric field of the high frequency power used for plasma formation acts in the thickness direction of the upper electrode 3, the first planar member 4, and the second planar member 5. Therefore, the electric field acts in the groove height direction of the first groove 7 and the second groove 9, and the groove height is an important parameter for preventing abnormal discharge. FIG. 6 shows the dependence of the discharge start voltage on the pd product (the product of the distance in the field action direction and the pressure) based on Paschen's law, which is used as a measure of the ease of discharge in space. It can be confirmed from FIG. 6 that when the pd product (the product of the distance in the electric field action direction and the pressure) on the horizontal axis is 1.5 Torr · cm or less, the discharge start voltage rapidly increases. A high discharge start voltage means that it is difficult for discharge to occur. In this embodiment, the processing pressure of the discharge space 11 is in the range of 1 × 10 ⁻³ Torr to 0.15 Torr, and the gas flow rate is 2000 sccm at the maximum. Under this use condition, the pressure in the first groove 7 and the second groove 9 is about 15 Torr at maximum. From the maximum pressure in the first groove 7 and the second groove 9 and FIG. 6, it can be said that the groove height × pressure (pd product) is preferably 1.5 Torr · cm or less in order to prevent abnormal discharge. . Therefore, it can be seen that abnormal discharge can be suppressed by setting the height of the first groove 7 and the second groove 9 to 1 mm or less. In this example, the height of the first groove 7 and the second groove 9 was set to 0.3 mm (pd product 0.5 Torr · cm or less) for the purpose of further improving safety. Since the groove width (3 mm in this embodiment) of the first groove 7 and the second groove 9 can be made relatively large, the gas in the plane direction can be obtained even if the groove height is 0.3 mm and there is a sufficient margin for abnormal discharge. Sufficient conductance can be secured, and uniform gas can be supplied into each diameter shown in FIG. If the groove width is too large, the contact areas of the upper electrode 3, the first planar member 4, and the second planar member 5 are reduced. Usually, the temperature of the upper electrode is controlled by the upper electrode temperature control means 24. If the contact area is small, heat transfer between the members cannot be sufficiently performed, and in particular, it is difficult to control the temperature of the second planar member 5 in contact with the plasma. It becomes. Therefore, it is desirable that the groove width has such a width that a contact area between the members can be secured by 50% or more. In the configuration shown in FIG. 3, the first groove 7 and the second groove 9 are concentrically arranged. However, if each gas hole is connected to act as a gas flow path, the first groove 7 and the second groove 9 are arranged in a radial, spiral, or lattice shape. You may arrange. However, considering the electric field distribution, a concentric circle shape or a lattice shape is desirable.

In the configuration shown in FIGS. 1, 2, and 3 in the present embodiment, the material of the first planar member 4 and the second planar member 5 is quartz (SiO ₂ ), but yttrium oxide (Y Needless to say, the same effect can be obtained by using ₂ O ₃ ), aluminum oxide (Al ₂ O ₃ ), silicon carbide (SiC) and silicon (Si). In the configuration shown in FIGS. 1, 2, and 3, the first planar member 4 and the second planar member 5 are made of the same material (quartz), but the above-described Y ₂ O ₃ and Al _{2 are used.} Needless to say, a combination of O ₃ , SiC, Si and quartz has the same effect. In particular, since the second planar member is in contact with the plasma 16, it is desirable to select it with priority on the high plasma resistance. For example, the second planar member is made of Y ₂ O ₃ and the first planar member is made of Y ₂ O ₃ or other materials, so that the effect of the present embodiment is reduced with less plasma consumption. The device can be realized. Further, the upper electrode 3 disposed at a position facing the sample 2 to be processed has a function as a counter ground for generating plasma and applying a high frequency voltage to the sample 2 to be processed. The conductivity and dielectric constant of the first planar member 4 and the second planar member 5 affect the plasma generation and the effect of opposing grounding of the high-frequency voltage applied to the sample 2 to be processed. From these viewpoints and from the viewpoint of plasma resistance, a combination of materials of the first planar member 4 and the second planar member 5 may be considered. For example, when both the first planar member 4 and the second planar member 5 shown in the embodiment are made of quartz (SiO ₂ ), the dielectric constant is low in terms of plasma generation (the relative dielectric constant of quartz). 4) is advantageous for plasma homogenization, but is disadvantageous because the impedance is high because the dielectric constant is low as the opposite ground. Therefore, the first planar member 4 is made of quartz, and the second planar member 5 has a high dielectric constant and can reduce the impedance as an opposing ground. Y ₂ O ₃ (the relative dielectric constant of Y ₂ O ₃ is about 11) In this case, it is possible to increase the function as an opposing ground with respect to the structure described in the embodiment and at the same time increase the plasma resistance.

  In this embodiment, the high-frequency power of 200 MHz is used for plasma formation and the high-frequency power applied to the workpiece 2 is 4 MHz. However, the present invention is the same when performing plasma generation and workpiece bias using other frequencies. Needless to say, there is a positive effect. Similarly, it goes without saying that the same effect can be obtained even in a configuration without a magnetic field by the solenoid coil 15.

  In this embodiment, the number of gas holes 8 in the first planar member 4 and the number of gas supply portions 6 applied to the upper electrode 3 are half of the number of gas holes in the second planar member 5. However, it is needless to say that the same effect can be obtained if the respective positions are arranged so as not to coincide with each other even if the same number or a further reduced number is formed.

  In this embodiment, the diameters of the gas holes 8 of the first planar member 4 and the gas holes 10 of the second planar member 5 are 0.4 to 0.5 mm. It goes without saying that the same effect can be obtained even when a gas pore diameter in the range is used.

In this embodiment, the upper electrode 3 is formed of a metal such as aluminum or selenium, but the surface and the portion in contact with the source gas are silicon oxide (SiO ₂ ), aluminum oxide) Al ₂ O ₃ , yttrium oxide (Y _2). By coating with either O ₃ ) or polyimide, it becomes possible to further reduce contamination and foreign matters.

  When etching a semiconductor film or an insulating film formed on a silicon wafer using a plasma etching apparatus having the configuration shown in FIGS. 1 to 3, the uniformity and reproducibility of the gas are improved as compared with the conventional case, Discharge conditions were relaxed, and wafer contamination and attached foreign matter were reduced.

  As described above, according to the present embodiment, even a parallel plate type plasma processing apparatus provides a plasma processing apparatus having stable plasma generation under a wide range of process conditions and processing performance excellent in uniformity and reproducibility. be able to.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, it is possible to add, delete, or replace another configuration for a part of a certain configuration.

  The present invention relates to a semiconductor device manufacturing apparatus, and more particularly to a plasma etching apparatus that performs an etching process of a semiconductor material using a pattern drawn by a lithography technique as a mask. According to the present invention, a uniform, reproducible and highly stable gas supply from a planar gas supply means arranged at a position facing a sample to be processed becomes possible. Furthermore, since the margin for suppressing the occurrence of abnormal discharge and contamination in the planar gas supply means can be greatly expanded, it is possible to greatly relax the restrictions on the discharge conditions that are normally performed to prevent these. As a result, a plasma processing apparatus capable of improving the uniformity of the processing speed, the uniformity of the processing shape, and the reproducibility thereof can be realized.

DESCRIPTION OF SYMBOLS 1 ... Sample to be processed installation means, 2 ... Sample to be processed, 3 ... Upper electrode, 4 ... 1st planar member, 5 ... 2nd planar member, 6 ... Gas supply part formed in upper electrode, 7 DESCRIPTION OF SYMBOLS 1st groove | channel, 8 ... Gas hole of 1st planar member 4, 9 ... 2nd groove | channel, 10 ... Gas hole of 2nd planar member 5, 11 ... Discharge space, 12 ... Matching device, 13 DESCRIPTION OF SYMBOLS ... High frequency power supply, 14 ... Vacuum container, 15 ... Solenoid coil, 16 ... Plasma, 17 ... High frequency power supply, 18 ... Matching device, 19 ... Cooling means, 20 ... Upper electrode, 21 ... Gas supply part, 22 ... Shower plate, 23 ... gas holes in the shower plate 22, 24 ... upper electrode temperature control means, 25 ... equipotential surface, 26 ... electric field.

Claims (16)

A processing chamber in which a sample is plasma-treated, a first electrode in which a high-frequency power for generating plasma is supplied and a gas supply unit to which a gas for generating the plasma is supplied is formed, and the first electrode In a plasma processing apparatus comprising a second electrode facing the electrode and on which the sample is placed,
A gas is supplied from a plurality of first gas holes penetrating the gas supply part, and a first gas supply plate disposed below the first electrode and a plurality of second gas passing through the first gas supply plate. A second gas supply plate that is supplied with gas from the second gas hole and disposed below the first gas supply plate;
The second gas supply plate has a plurality of third gas holes penetrating through the inside and supplies the gas supplied from the second gas hole into the processing chamber from the third gas hole,
The first gas hole and the second gas hole are connected to any of a plurality of ring-shaped first gas flow paths having different radii,
The second gas hole and the third gas hole are connected to any of a plurality of ring-shaped second gas flow paths having different radii,
The first flow path is formed in the gas supply unit or the first gas supply plate,
The second flow path is formed in the second gas supply plate or the first gas supply plate disposed above the second electrode,
The first gas flow path in the plan view and the second gas flow path in the plan view overlap,
The first gas hole is located in the gas supply section so that the first gas hole in the plan view of the second gas supply plate is located next to one of the third gas holes in the plan view. Formed,
The second gas hole is formed in the first gas supply plate so that the second gas hole in the plan view is located next to the other of the third gas hole in the plan view. A plasma processing apparatus. The plasma processing apparatus according to claim 1,
The plasma processing apparatus, wherein the first flow path and the second flow path are formed in the first gas supply plate. The plasma processing apparatus according to claim 2, wherein
The material of the first electrode is a conductor,
The plasma processing apparatus, wherein the first gas supply plate and the second gas supply plate are made of silicon oxide, silicon, yttrium oxide, or aluminum oxide. The plasma processing apparatus according to claim 3, wherein
The plasma processing apparatus, wherein the material of the first gas supply plate and the material of the second gas supply plate are quartz. The plasma processing apparatus according to claim 4, wherein
The plasma processing apparatus, wherein the number of the first gas holes and the number of the second gas holes are smaller than the number of the third gas holes. The plasma processing apparatus according to claim 5, wherein
The number of the first gas holes is half of the number of the third gas holes,
The number of said 2nd gas holes is a half of the number of said 3rd gas holes, The plasma processing apparatus characterized by the above-mentioned. The plasma processing apparatus according to claim 2, wherein
The plasma processing apparatus, wherein a dielectric constant of the first gas supply plate is smaller than a dielectric constant of the second gas supply plate. The plasma processing apparatus according to claim 2, wherein
A temperature control means for controlling the temperature of the first electrode;
The gas supply unit contacts the first gas supply plate,
The first gas supply plate is in contact with the second gas supply plate;
The cross-sectional shape of the first channel and the second channel is a groove shape,
The width of the first flow path is such that the contact area between the gas supply part and the first gas supply plate is 50% or more,
The width of the second flow path is such that the contact area between the first gas supply plate and the second gas supply plate is 50% or more,
The depth of the first channel is a depth at which the product of the pressure in the first channel and the depth is 1.5 Torr × cm,
The depth of the second flow path is a depth at which the product of the pressure in the second flow path and the depth is 1.5 Torr × cm or less,
The plasma treatment characterized in that the hole diameter of the first gas hole, the hole diameter of the second gas hole, and the hole diameter of the third gas hole are each in the range of 0.1 mm to 1.0 mm. apparatus. A processing chamber in which a sample is plasma-treated, a first electrode in which a high-frequency power for generating plasma is supplied and a gas supply unit to which a gas for generating the plasma is supplied is formed, and the first electrode In a plasma processing apparatus comprising a second electrode facing the electrode and on which the sample is placed,
A gas is supplied from a plurality of first gas holes penetrating the gas supply part, and a first gas supply plate disposed below the first electrode and a plurality of second gas passing through the first gas supply plate. A second gas supply plate that is supplied with gas from the second gas hole and disposed below the first gas supply plate;
The second gas supply plate has a plurality of third gas holes penetrating through the inside and supplies the gas supplied from the second gas hole into the processing chamber from the third gas hole,
The first gas hole and the second gas hole are connected to any of a plurality of ring-shaped first gas flow paths having different radii,
The second gas hole and the third gas hole are connected to any of a plurality of ring-shaped second gas flow paths having different radii,
The first flow path is formed in the gas supply unit or the first gas supply plate,
The second flow path is formed in the second gas supply plate or the first gas supply plate disposed above the second electrode,
The position of the first gas hole in the plan view of the second gas supply plate is different from the position of the second gas hole in the plan view and the position of the third gas hole in the plan view. Gas holes are formed in the gas supply unit,
The second gas hole is formed in the first gas supply plate so that the position of the second gas hole in the plan view is different from the position of the third gas hole in the plan view. A plasma processing apparatus. The plasma processing apparatus according to claim 9, wherein
The first flow path and the second flow path are formed in the first gas supply plate,
The plasma processing apparatus, wherein the first gas flow path in the plan view and the second gas flow path in the plan view overlap. The plasma processing apparatus according to claim 10, wherein
The material of the first electrode is a conductor,
The plasma processing apparatus, wherein the first gas supply plate and the second gas supply plate are made of silicon oxide, silicon, yttrium oxide, or aluminum oxide. The plasma processing apparatus according to claim 11, wherein
The plasma processing apparatus, wherein the material of the first gas supply plate and the material of the second gas supply plate are quartz. The plasma processing apparatus according to claim 12, wherein
The plasma processing apparatus, wherein the number of the first gas holes and the number of the second gas holes are smaller than the number of the third gas holes. The plasma processing apparatus according to claim 13, wherein
The number of the first gas holes is half of the number of the third gas holes,
The number of said 2nd gas holes is a half of the number of said 3rd gas holes, The plasma processing apparatus characterized by the above-mentioned. The plasma processing apparatus according to claim 10, wherein
The plasma processing apparatus, wherein a dielectric constant of the first gas supply plate is smaller than a dielectric constant of the second gas supply plate. The plasma processing apparatus according to claim 10, wherein
A temperature control means for controlling the temperature of the first electrode;
The gas supply unit contacts the first gas supply plate,
The first gas supply plate is in contact with the second gas supply plate;
The cross-sectional shape of the first channel and the second channel is a groove shape,
The width of the first flow path is such that the contact area between the gas supply part and the first gas supply plate is 50% or more,
The width of the second flow path is such that the contact area between the first gas supply plate and the second gas supply plate is 50% or more,
The depth of the first channel is a depth at which the product of the pressure in the first channel and the depth is 1.5 Torr × cm,
The depth of the second flow path is such that the product of the pressure in the second flow path and the depth is 1.5 Torr × cm or less.

Images