JPH058937U - Parallel plate type plasma etching equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] Prevents the expansion of the plasma generation region, particularly the generation of plasma on the exhaust rings 30 and 40, and enables uniform etching of large-diameter wafers and high aspect ratio. To provide a parallel plate type plasma etching apparatus capable of forming a pattern excellent in directionality. [Constitution] Etching gas introduction passage 15 and exhaust passage 30
a, 40a, upper electrode 11, lower electrode 13, wafer clamp 17, etc., in the parallel plate type plasma etching apparatus, wherein the exhaust passages 30a, 40a have a bent cross-sectional shape. Etching equipment.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention includes a parallel plate type plasma etching apparatus, more specifically, an etching gas introduction path, an exhaust path, an upper electrode, a lower electrode, a wafer clamp, etc., for forming a fine pattern of an integrated circuit on a wafer. The present invention relates to a parallel plate type plasma etching device used in.

[0002]

[Prior Art]

 In manufacturing a large-scale integrated circuit, it is necessary to form a fine pattern on a semiconductor wafer, and a dry etching apparatus is mainly used for this purpose.

Various types of dry etching apparatuses have been devised up to now, but in the manufacture of a large scale integrated circuit having a high degree of integration, a parallel plate type capable of forming a fine pattern with good reproducibility. Plasma etching devices are becoming the mainstream.

FIG. 4 schematically shows a conventional parallel plate type plasma etching apparatus of this kind. In the figure, reference numeral 10 denotes a processing chamber. An upper electrode 11 is provided above the processing chamber 10, and a lower electrode 13 is provided below the processing chamber 10 so as to face the upper electrode 11. ing. A wafer 12 is placed on the upper surface of the lower electrode 13, and a vacuum exhaust system 14 is disposed below the outer periphery of the lower electrode 13, and the vacuum exhaust system 14 is mainly composed of an exhaust ring 14 a. .. A seal plate 20 is disposed above the upper electrode 11, and a gas introduction passage 15 is formed in the center of the seal plate 20. The gas introduction passage 15 is a gas supply source (see FIG. Connected (not shown). A clamp plate 17 for fixing the wafer 12 to the lower electrode 13 is attached to the seal plate 20 side. A high-frequency power source 16 is connected to the upper electrode 11 and the lower electrode 13, and by applying high-frequency power from the high-frequency power source 16 to the upper electrode 11 or the lower electrode 13, the reaction gas supplied from the gas introduction passage 15 is supplied. Is converted into plasma and the wafer 12 is subjected to etching processing.

In performing this etching process, as the diameter of the wafer 12 becomes larger, plasma concentration on the wafer 12 and expansion of the plasma stable region are required, and the pattern is miniaturized. As a result, the directivity of ions is required more in the large-diameter wafer 12. Therefore, the pressure in the processing chamber 10 can be reduced.

[0006]

[Problems to be solved by the device]

 However, when the pressure in the processing chamber 10 is reduced, the plasma generation region in the processing chamber 10 gradually expands as indicated by A, B and C in the figure. That is, plasma is also generated from the area A, which is a normal plasma generation area, to the area B on the exhaust ring 14a, and the plasma generation area is expanded to above the outer peripheral portion of the clamp plate 17. Such an expansion of the plasma generation region undesirably lowers the etching efficiency of the wafer 12 and adversely affects the device components such as the exhaust ring 14a.

Therefore, as a conventional method for preventing the expansion of such a plasma generation region, an electric field concentrating ring (not shown) made of an insulator or a conductor covered with an insulator on the outer periphery of the wafer 12 is used. Has been proposed, and a method of concentrating plasma above the wafer 12 by this electric field concentrating ring has been proposed.

However, in the method described above, the electric field changes sharply at the boundary between the wafer 12 and the electric field concentration ring, so that the etching rate at the outer peripheral portion of the wafer 12 is different from that at the central portion of the wafer 12. There is a problem that the uniformity of etching in the wafer 12 is reduced.

The present invention has been devised in view of the above problems, and it is possible to prevent the expansion of the plasma generation region, particularly to prevent the generation of plasma on the exhaust ring, and to perform uniform etching even on a large-diameter wafer. At the same time, it aims to provide a parallel plate type plasma etching apparatus capable of forming a pattern excellent in anisotropy even with a high aspect ratio.

[0010]

[Means for Solving the Problems]

 In order to achieve the above object, the parallel plate type plasma etching apparatus according to the present invention is a parallel plate type plasma etching apparatus having an etching gas introduction path, an exhaust path, an upper electrode, a lower electrode, a wafer clamp, etc. The feature is that the cross-sectional shape of the road is curved.

[0011]

[Action]

 According to the above structure, the exhaust gas exhaust passage has a bent cross-sectional shape, which lengthens the exhaust passage of the etching gas, which results in a gradual electric field gradient in the exhaust passage. Less plasma is generated on the top.

[0012]

【Example】

 An embodiment of a parallel plate type plasma etching apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a parallel plate type plasma etching apparatus according to the present embodiment, and 10 in the drawing shows a processing chamber. An upper electrode 11 is fixedly arranged on a retaining ring 22 made of Teflon at the upper part of the processing chamber 10, and a distance of 5 mm from the upper electrode 11 is provided at the lower part of the processing chamber 10 facing the upper electrode 11. The lower electrode 13 is provided so as to be kept. A seal plate 20 is disposed above the upper electrode 11, and a gas introduction passage 15 is formed in the center of the seal plate 20. The gas introduction passage 15 is a gas supply source ( (Not shown). A baffle plate 21 is interposed between the seal plate 20 and the upper electrode 11, and etching gas is introduced into the processing chamber 10 through an opening (not shown) formed in the baffle plate 21. It is being supplied. A clamp plate 17 for fixing the wafer to the lower electrode 13 is attached to the seal plate 20 side, and the surface of the clamp plate 17 is anodized.

A coolant circulation passage 13 a for circulating a coolant is formed inside the lower electrode 13 by being covered with a circulation passage covering member 27. A wafer (not shown) is placed on the upper surface of the lower electrode 13, a vacuum exhaust system 14 is arranged below the outer periphery of the lower electrode 13, and the lower electrode 13 is fixed to a base 24. ..

The vacuum exhaust system 14 is mainly composed of an exhaust ring 30 and a support base 26 in which a groove 31 connected to the ground is formed, and an exhaust passage 30 a is formed in the exhaust ring 30. The exhaust passage 30a communicates with an exhaust port (not shown) formed in the support base 26 through the groove 31, and this exhaust port is connected to a vacuum exhaust device. As shown in FIG. 2 (a), the cross-sectional shape of the exhaust passage 30a has a bent shape with a step portion, and the exhaust passage 30a has a linear shape as shown in FIG. 2 (c). In comparison, the length of the exhaust passage 30a is longer. Therefore, the electric field gradient from the processing chamber 10 to the ground is gentle.

In another embodiment of the exhaust ring, as shown in FIG. 2B, the exhaust passage 40a formed inside the exhaust ring 40 has a shape in which it is bent in multiple stages. The length of the exhaust passage 40a is longer than that of the embodiment shown in (a).

A gas channel 28 is formed in the base 24, and this gas channel 28 is also extended in the lower electrode 13 so that a He gas is passed through the gas channel 28 so that the lower electrode 13 and It is designed to transfer heat to the wafer. The base 24 is fixed to a support 26 via an insulating ring 25.

A high-frequency power source (not shown) is connected to the upper electrode 11 and the lower electrode 13, and high-frequency power is applied to the upper electrode 11 or the lower electrode 13 from this high-frequency power source so that the gas introduction path 15 can be discharged. The supplied reaction gas is turned into plasma and the wafer is etched.

Next, the results of experiments on the plasma generation state on the exhaust rings 30, 40, 18 using the apparatus of the above-described embodiment and the apparatus of the comparative example shown in FIG. 2C are shown. First, the wafer on which SiO ₂ is deposited is fixed to the lower electrode 13 by the clamp plate 17, and a mixed gas of CF ₄ of 20 sccm, CHF ₃ of 20 sccm and Ar of 300 sccm is introduced into the processing chamber 10 from the gas introduction passage 15. Introduce. At the same time, the pressure inside the processing chamber 10 is maintained at 800 mmToor by exhausting from the exhaust port. Next, a high frequency voltage having a frequency of 400 kHz and a maximum voltage of 1.5 kw is applied between the upper electrode 11 and the lower electrode 13. Table 1 below shows the results of an investigation of the plasma generation conditions under the above conditions.

[0019]

[Table 1] Exhaust path shape Exhaust path bending number Plasma generation status Fig. 2 (a) 2 Almost no generation Fig. 2 (b) 4 No generation completely Fig. 2 (c) 0 Quite a lot In the device according to the embodiment in which the passages 30a and 40a are bent, almost no plasma is generated on the exhaust rings 30 and 40, and good results are obtained. It is effective to form a bent portion in the exhaust passage. It turns out that

[0020]

[Effect of the device]

 As is clear from the above description, in the parallel plate type plasma etching apparatus according to the present invention, a parallel plate type plasma equipped with an etching gas introduction path, an exhaust path, an upper electrode, a lower electrode, a wafer clamp, etc. In the etching device, since the cross-sectional shape of the exhaust passage is bent, the electric field gradient near the exhaust passage can be relaxed, and the generation of plasma above the exhaust passage can be effectively prevented. .. Therefore, the expansion of the plasma generation region is prevented, in particular, the generation of plasma on the exhaust ring is prevented, uniform etching is performed even on a large-diameter wafer, and a pattern with excellent anisotropy even at high aspect ratios It is possible to provide a parallel plate type plasma etching apparatus capable of forming a plasma.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a parallel plate type plasma etching apparatus according to the present invention.

2A is a sectional view of an exhaust ring showing the shape of an exhaust passage according to an embodiment, FIG. 2B is a sectional view of an exhaust ring showing the shape of an exhaust passage according to another embodiment, and FIG. FIG. 6 is a cross-sectional view of an exhaust ring showing the shape of an exhaust passage according to a comparative example.

FIG. 3 is a plan view showing an outline of an exhaust ring.

FIG. 4 is a schematic sectional view showing a conventional parallel plate type plasma etching apparatus.

Claims (1)

[Claims for utility model registration] 1. In a parallel plate type plasma etching apparatus provided with an etching gas introduction passage, an exhaust passage, an upper electrode, a lower electrode, a wafer clamp, etc., the exhaust passage has a bent cross-sectional shape. A parallel plate type plasma etching apparatus characterized in that