JPH0896990A - Plasma treatment device and plasma treatment method - Google Patents

Abstract

PURPOSE: To provide a plasma treatment device and a plasma treatment method in which a bell jar is never locally heated nor spattered. CONSTITUTION: A microwave excited by a magnetron 1 is guided to a plasma generating chamber 4 via a waveguide 2 to generate a helicon wave, which is then propagated by an inner circumferential solenoid coil 6. According to such a constitution in which a RF antenna is dispensed with, the field intensity is never made uneven by the antenna. Therefore, a stable plasma treatment can be performed without the spattering of the plasma generating chamber. Since a plasma generating chamber heater 5 can be provided, the accumulation of a reaction product can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus and a plasma processing method used in a manufacturing process of semiconductor devices and the like. The present invention relates to a plasma processing apparatus and a plasma processing method suitable for use in some cases.

[0002]

2. Description of the Related Art With the progress of higher integration and higher performance of semiconductor devices such as LSI, the minimum design rule is reaching the level of sub-half micron, and the target substrate to be plasma-processed is A large-diameter semiconductor substrate with a diameter of more than 8 inches and a large-area LCD panel are being adopted.

There is an urgent need to establish a fine processing technique for highly accurately and uniformly performing plasma processing such as plasma etching or plasma CVD on such a large-diameter substrate. Therefore, in place of the conventional parallel plate type RIE plasma processing apparatus and ECR plasma processing apparatus, the helicon wave plasma processing apparatus and ICP (Inductively)
Coupled Plasma) processing device and TCP
(Transformer Coupled Plas
ma) A processing device is under consideration. A review article on these new plasma sources can be found, for example, in the monthly Semiconductor World magazine (Press Journal, Inc.), October 1993, p. 59.

[0004] These plasma processing apparatuses have a simple apparatus configuration in which an RF antenna that requires a small installation space and a weak magnetic field applying means of 0.0875T or less are adopted as compared with an ECR plasma processing apparatus that is an electrodeless discharge. Therefore, there is an advantage that it can contribute to downsizing of the device and space saving in the clean room. In addition to this, in particular, the helicon wave plasma processing apparatus is 10 ¹³ / cm even under a low pressure of the order of 10 ^-1 Pa as compared with the conventional plasma processing apparatus.
There is an advantage that ^three high-density plasmas can be obtained. Taking advantage of this feature, it is expected that the device will be downsized and that it will be applied to a uniform and high-throughput process for a large-sized substrate to be processed.

This helicon wave plasma processing apparatus, as disclosed in, for example, US Pat. No. 5,091,049, comprises a loop-shaped RF antenna formed by winding a quartz or Pyrex verger and a solenoid coil. It is a major component. With this configuration, a helicon wave (Whistler wave) is generated in the bell jar from the looped RF antenna, energy is transferred from the helicon wave to the electron via the process of Landau damping, and this is accelerated to process high-speed electrons. It is a characteristic of the helicon wave plasma source that high ion current density is obtained by colliding with gas molecules. The magnetic field generated by the solenoid coil contributes to the propagation of the generated helicon wave.

[0006]

In the process of generating the helicon wave plasma described above, the bell jar near the loop-shaped RF antenna having a large electric field strength is locally heated, or the inner wall of the bell jar is treated. It has been pointed out that a phenomenon in which gas ions are strongly sputtered. Therefore, the constituent material of the chamber is released into the plasma, and the substrate to be processed is contaminated. Further, in the plasma etching, it is observed that the pattern conversion difference occurs due to the excessive deposition of the reaction product due to the release of oxygen in the bulger-forming material. Furthermore, damage to the bell jar also poses a problem in terms of equipment maintenance.

Therefore, an object of the present invention is to provide a high-density plasma processing apparatus which is free from damage due to sputtering of a bell jar and emission of impurities.

Another object of the present invention is to provide a plasma processing method using the above plasma processing apparatus, which can perform high-density plasma processing on a substrate to be processed with high uniformity without pattern conversion and with low contamination. It is to be. Other problems of the present invention will be made clear by the description of the present specification and the accompanying drawings.

[0009]

A plasma processing apparatus and a plasma processing method according to the present invention are proposed to solve the above-mentioned problems, and a magnetron disposed at one end of a microwave waveguide and the microwave waveguide. A plasma generation chamber connected to the other end of the tube through a microwave introduction window, a helicon wave propagating magnetic field generation means arranged around the plasma generation chamber, and a plasma generation chamber connected to the plasma wave generation chamber and covered inside. A plasma processing apparatus comprising a plasma diffusion chamber in which a processing substrate is arranged.

It is desirable to further have a magnetic field generating means for plasma transportation around the plasma generating chamber.

It is also desirable to have wall heating means for the plasma generation chamber.

Furthermore, at least a part of the plasma diffusion chamber is provided with a Si-based material, and the Si-based material is further provided.
It is further desirable to have a heating means for the system material.

In the plasma processing method of the present invention, the plasma processing apparatus described above performs a predetermined plasma processing on the substrate to be processed.

[0014]

The point of the plasma processing apparatus of the present invention is that a high frequency wave in the microwave band (1 GHz to 100 GHz) is used as the excitation power source of the helicon wave plasma. That is, the microwave oscillated by the magnetron is
The whistler wave is generated by introducing the plasma into the plasma generation chamber through the microwave guide window and the microwave introduction window. After that, the helicon wave generated by the helicon wave propagation magnetic field generating means is propagated from one direction into the plasma generation chamber. The magnetic field strength for helicon wave propagation may be in the range of several mT to several tens mT.

The conventional helicon wave plasma processing apparatus uses 1 MHz to several tens of MH as a power source for plasma excitation.
It used frequencies in the RF band up to the z-order. Therefore, it is difficult to transport power using a waveguide, and a loop-shaped RF antenna is wound around the bell jar to excite a helicon wave in the bell jar by electromagnetic induction. Therefore, concentration of an electric field in the vicinity of the antenna locally heats the bell jar, or the inner wall of the bell jar is sputtered to release impurities, which is a basic problem due to the RF antenna structure.

According to the plasma processing apparatus of the present invention, since the antenna structure is not used basically, the sputtering of the microwave introduction window and the inner wall of the plasma generating chamber by such sputtering does not occur. Therefore,
Impurity contamination does not occur in principle, and neither the microwave introduction window nor the inner wall of the plasma generation chamber is worn.

Since the helicon wave plasma generation mechanism is not based on electromagnetic induction, there is no limitation on the material of the plasma generation chamber. Therefore, it is possible to prevent the deposition of reaction products on the inner wall of the plasma generation chamber by providing a heater by resistance heating or the like in the wall of the plasma generation chamber.

If the magnetic field generating means for plasma transportation is arranged further on the outer periphery of the magnetic field generating means for propagating helicon waves arranged around the plasma generating chamber, the plasma is effectively and uniformly transferred to the plasma diffusion chamber. It is possible.

The points of the plasma processing method of the present invention are:
The point is that a high-density plasma is used to perform uniform plasma processing even on a large-area substrate to be processed using the plasma processing apparatus described above. Therefore, stable plasma processing can be performed without being affected by the impurities emitted by sputtering.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the accompanying drawings.

Example 1 This example is an example in which a contact hole was formed by using a helicon wave plasma etching apparatus using microwave excitation, which is shown in FIGS. 1 and 3 (a)-(b). And explain.

FIG. 1 is a diagram showing a schematic configuration example of the helicon wave plasma processing apparatus of this embodiment. The microwave excited by the magnetron 1 passes through the microwave waveguide 2,
The light enters the plasma generation chamber 4 through the microwave introduction window 3 such as quartz. The plasma generation chamber 4 is, for example, A
It is made of an l-based metal and has a built-in plasma generation chamber heater 5 by resistance heating. The helicon wave generated in the plasma generation chamber 4 propagates by the magnetic field generated by the inner circumference solenoid coil 6 wound around the plasma generation chamber 4, and further the outer circumference solenoid coil 7 wound around the inner circumference solenoid coil 6. Are transported to the plasma diffusion chamber 8 by the magnetic field generated by. A multi-pole magnet 9 is provided on the outer periphery of the plasma diffusion chamber 8,
The plasma is prevented from disappearing due to contact between the plasma and the inner wall of the plasma diffusion chamber 8. The substrate stage 11 is arranged in the plasma diffusion chamber on the central axis of the plasma generation chamber 4, and the substrate 10 to be processed is placed there. Reference numeral 12 is a substrate bias power supply that supplies a substrate bias to the substrate to be processed 10. This apparatus has a Si plate 13 and a Si plate heater 1 on the upper wall surface of the plasma diffusion chamber 8.
4 is provided to scavenge excess fluorine radicals (F ^* ). It should be noted that details of the temperature control means of the substrate stage 11, the fixing means of the substrate 10 to be processed, the introduction / exhaust means of the processing gas, and the like are omitted in the figure. According to this plasma processing apparatus, whistler waves can be generated without an RF antenna, and in principle, the plasma generation chamber 4 and the microwave introduction window 3 are not contaminated by sputtering.

Next, a specific example of the plasma etching method of the present invention will be described with reference to FIGS. The sample used in the present embodiment is, for example, an inter-layer insulating film 22 made of SiO ₂ and 700
It is formed to a thickness of nm, and a resist mask 23 for opening a contact hole is further formed. The resist mask 23 is formed with a chemically amplified resist and excimer laser lithography so as to have an opening width of 0.25 μm. This sample shown in FIG. 3A is a substrate to be processed. In FIG. 3A, active layers such as impurity diffusion layers are not shown.

The substrate 10 to be processed was placed on the substrate stage 11 of the plasma processing apparatus shown in FIG. 1 and, as an example, the exposed portion of the interlayer insulating film 22 was etched under the following conditions. C ₄ F ₈ Flow rate 100 sccm Gas pressure 0.1 Pa Microwave power source power 1500 W (2.45 GH
z) Substrate bias power supply power 200 W (2 MHz) Substrate temperature to be processed Normal temperature Plasma generation chamber temperature 250 ° C Si plate temperature 250 ° C In this etching process, a large amount of CF _x ⁺ ions are generated in high-density plasma to cause interlayer insulation. High-speed etching of the film 22 progresses, and the contact hole 28 is opened as shown in FIG. In a carbon-rich gas such as C ₄ F ₈ , the CF-based polymer is likely to be deposited on the inner wall of the chamber and easily become a source of particle contamination.
However, in the plasma processing apparatus of this embodiment, since the plasma is not excited by the RF antenna, the resistance heating heater on the inner wall of the plasma generation chamber can be provided, and since it is heated to 250 ° C., no deposition is seen. Further, since a large amount of excess F ^* generated in the plasma is consumed on the surface of the heated Si plate 13, the etching selection ratio with respect to the lower semiconductor substrate 21 is 50 or more, and the impurity diffusion layer is not damaged. This Si plate has the F ^* scavenging effect even without heating. Further, since the inner wall of the plasma generation chamber 4 is not sputtered, the substrate 10 to be processed is not contaminated.

Embodiment 2 This embodiment is an example in which a refractory metal polycide electrode is formed by using a helicon wave plasma etching apparatus by microwave excitation. This is shown in FIGS. 2 and 4 (a).
This will be described with reference to (b).

FIG. 2 is a diagram showing a schematic configuration example of the helicon wave plasma processing apparatus of this embodiment. This apparatus has basically the same configuration as the plasma processing apparatus shown in FIG. 1, and the plasma generation chamber 4 is made of a dielectric material such as SiO ₂ or Al ₃ O ₃ Plate 1
3 is different from the apparatus of FIG. 1 only in that the heater 3 and the Si plate heater 14 are removed. Since other components are the same, duplicate description will be omitted. This plasma processing apparatus can also generate whistler waves without an RF antenna, and in principle, the plasma generation chamber 4 and the microwave introduction window 3 are not contaminated by sputtering.

Next, a specific example of the plasma etching method of the present invention will be described with reference to FIGS. The sample used in this embodiment is, for example, a gate insulating film 24 made of SiO ₂ and n ⁺ on a semiconductor substrate 21 such as Si having a diameter of 8 inches.
A polycrystalline silicon layer 25, a refractory metal silicide layer 26 made of WSi _x , an antireflection film 27 made of SiON, and a resist mask 23 are formed. This resist mask 23 is formed with a chemically amplified resist and a pattern width of 0.25 μm by excimer laser lithography. The thickness of each layer is, for example, 10 nm for the gate insulating film 24 and 70 n for the n ⁺ polycrystalline silicon layer 25.
m, refractory metal silicide layer 26 is 100 nm, SiO
The antireflection film 27 made of N has a thickness of 25 nm. Figure 4
This sample shown in (a) is used as a substrate to be processed.

The substrate 10 to be processed is placed on the substrate stage 11 of the plasma processing apparatus shown in FIG. 2, and as an example, the antireflection film 27 and the refractory metal silicide layer 26 are etched under the following first condition. It was Cl ₂ flow rate 95 sccm O ₂ flow rate 5 sccm Gas pressure 0.1 Pa Microwave power source power 2000 W (2.45 GH
z) Substrate bias power supply power 80 W (2 MHz) Substrate temperature to be processed Normal temperature Plasma generation chamber temperature 250 ° C. In this etching step, a large amount of Cl ⁺ ions generated in the high density plasma causes W is an oxychloride with high vapor pressure WCl _x O
_{As y} , and Si in the refractory metal silicide layer 26 becomes SiCl _x, and etching proceeds. Along with this, decomposition products of the resist mask 23 containing Cl and W,
The side reaction product containing Si, C or O serves as a sidewall protective film (not shown), and anisotropic etching proceeds.

Next, the exposed portion of the n ⁺ polycrystalline silicon layer 25 was etched under the following second condition. The switching of the etching conditions is the characteristic emission spectrum of W observed during the etching of WSi _x 40
It was the time when the emission intensity of 1 nm or 430 nm started to decrease. HBr flow rate 95 sccm O ₂ flow rate 5 sccm Gas pressure 0.1 Pa Microwave power supply power 2500 W (2.45 GH
z) Substrate bias power supply power 80 W (2 MHz) Substrate temperature to be processed Normal temperature Plasma generation chamber temperature 250 ° C. In the above etching process, the n ⁺ polycrystalline silicon layer 25 is removed by forming SiBr _x, while SiBr _x is removed.
Anisotropic etching proceeds while forming a side wall protective film (not shown) of _x O _y . The polycide gate electrode after completion of etching is shown in FIG.

In this embodiment, since Whistler waves can be generated without an RF antenna, the influence of oxygen released from the constituent material of the plasma generation chamber 4 by the sputtering of the inner wall of the plasma generation chamber 4 as in the conventional apparatus. There is no. Therefore, it is possible to perform patterning without pattern conversion difference due to excessive deposition of reaction products. Further, since the plasma generation chamber is heated to 250 ° C., it is possible to prevent deposition of the sidewall protective film forming material in the chamber during patterning of the polycide gate electrode, and it is possible to perform plasma processing without particle contamination.

Although the present invention has been described with reference to the two examples, the present invention is not limited to these examples.

For example, although the application to the plasma etching apparatus has been exemplified as the plasma processing apparatus, the present invention can be applied to all surface processing apparatuses that apply high-density plasma, such as a plasma ashing apparatus and a plasma CVD apparatus.

[0033]

As is apparent from the above description, according to the plasma processing apparatus of the present invention, plasma processing using high ion current density by helicon wave plasma can be performed without using an RF antenna. Therefore, local heating or sputtering of the inner wall of the plasma generation chamber does not occur, and the plasma generation chamber is not damaged. Since the heater can be built in the plasma generation chamber, there is no deposition of reaction products and a process with less particle contamination is possible.

According to the plasma processing method of the present invention,
It is possible to perform plasma processing with good controllability, with low contamination of the substrate to be processed and without deposition of excessive reaction products.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a plasma processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view of a plasma processing apparatus according to a second embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view for explaining the plasma processing method according to the first embodiment of the present invention in the order of steps thereof,
(A) is a state in which an interlayer insulating film and a resist mask are formed on a semiconductor substrate, and (b) is a state in which a contact hole is formed in the interlayer insulating film.

FIG. 4 is a schematic cross-sectional view for explaining a plasma processing method according to a second embodiment of the present invention in the order of steps thereof,
(A) shows a state in which a gate insulating film, a polycrystalline silicon interlayer insulating film, a refractory metal silicide layer and an antireflection film are sequentially formed on a semiconductor substrate, and a resist mask is further formed,
(B) is a state in which the refractory metal polycide pattern is completed.

[Explanation of symbols]

1 magnetron 2 microwave waveguide 3 microwave introduction window 4 plasma generation chamber 5 plasma generation chamber heater 6 inner circumference solenoid coil 7 outer circumference solenoid coil 8 plasma diffusion chamber 9 multipole magnet 10 processed substrate 11 substrate stage 12 substrate bias power supply 21 Semiconductor substrate 22 Interlayer insulating film 23 Resist mask 24 Gate insulating film 25 n ⁺ Polycrystalline silicon layer 26 Refractory metal silicide layer 27 Antireflection film 28 Contact hole

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/3065

Claims (6)

[Claims] 1. A magnetron disposed at one end of a microwave waveguide, a plasma generation chamber connected to the other end of the microwave waveguide through a microwave introduction window, and disposed around the plasma generation chamber. A plasma processing apparatus comprising: the helicon wave propagating magnetic field generating means and a plasma diffusion chamber that is connected to the microwave generating chamber and has a substrate to be processed therein. 2. The plasma processing apparatus according to claim 1, further comprising magnetic field generating means for plasma transportation, which is arranged around the plasma generating chamber. 3. The plasma processing apparatus according to claim 1, further comprising wall heating means for the plasma generating chamber. 4. At least one in the plasma diffusion chamber
The plasma processing apparatus according to claim 1, wherein a Si-based material is provided in the portion. 5. The plasma processing apparatus according to claim 4, further comprising heating means for the Si-based material. 6. A plasma processing method, wherein a predetermined plasma processing is performed on a substrate to be processed by the plasma processing apparatus according to claim 1.