JPH01298170A - Ecr plasma treatment apparatus - Google Patents

Abstract

PURPOSE:To form a film on the surface of a specimen with superior uniformity and also to facilitate the control of film formation by introducing a reactant gas through plural gas outlet pipes including a gas outlet pipe in the vinicinity of the outside periphery of a specimen and carrying out ECR reaction. CONSTITUTION:Microwaves from a microwave source 1 are introduced via a waveguide 2 into an electric discharge chamber 3, by which a plasma gas supplied through a gas-introducing hole 4 is formed into plasmic state. The resulting plasma is supplied into a film-forming chamber 7 in the form of a plasma stream P by means of a coil 5. A reactant gas is further supplied through reactant gas outlet pipes 10A, 10b into the above film-forming chamber 7 and allowed to react with the above plasma gas, by which a film is formed on the surface of a specimen W. In the above ECR plasma treatment apparatus, one reactant gas outlet pipe 10A is disposed apart from the specimen W, through which the reactant gas is allowed to flow uniformly in the film- forming chamber 7. The other outlet pipe 10B is disposed in the vicinity of the outside periphery of the specimen W, by which the reactant gas is allowed to flow in large quantities on the periphery of the specimen W. By this method, uniform film formation can be performed and film-forming speed can be easily controlled by regulating respective flow velocities of the reactant gases.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an apparatus for processing a sample such as a wafer substrate using plasma generated by electron cyclotron resonance (ECR).

[Prior Art] There is a conventional ECR plasma processing apparatus as shown in FIG. In this device, microwaves generated by a microwave source 1 are introduced into a discharge chamber 3 via a waveguide 2. A gas that becomes a plasma generation source, for example, N2.08, Ar, etc., is introduced into the discharge chamber 3 through the gas introduction CI 4, and a magnetic field is generated by a coil 5 provided on the outer periphery, where the magnetic field and microwave When the ECR condition is satisfied, the electric field energy is efficiently absorbed by the charged particles and a highly active plasma is generated. 7' is introduced. Film forming chamber 7'
A sample W to be formed into a film is placed on a sample stage 8, and a reactive gas such as SiH4 is introduced from a gas discharge tube 10 in a vacuum state. Film formation progresses on the W surface.

In other words, if the plasma is N2 plasma, it will react with silane gas (SiH,) and form a silicon nitride film (S) on the sample.
iN,) is attached. In addition, if O2 plasma is used, a silicon oxide film (SiO2) is deposited on the sample. Furthermore, impurity doping can be performed using Ar plasma and boron or phosphorus. In this case, in order to increase the reactivity between the plasma and the reaction gas and the uniformity of the reaction, the reaction gas is introduced into the film forming chamber 7.
The gas discharge pipe 10 introduced into the gas discharge pipe 10 has a ring shape as shown in FIG.
The reactant gas is released uniformly from the

[Problems to be Solved by the Invention] Incidentally, in such a conventional ECR plasma processing apparatus, the reaction gas discharged from the gas discharge tube 1o exists almost uniformly in the film forming chamber 7' due to diffusion. The deposition rate depends on the intensity of the plasma introduced. Therefore, since the plasma intensity is high at the center of the plasma flow, the film formation rate becomes faster at the center of the sample W, as shown in FIG. 6, and uniformity of film formation cannot be obtained.

In particular, this tendency increases as the diameter of the sample increases.

For example, in the case of a wafer of 100 mm+φ, a uniformity of only ±5% was obtained, and for a wafer of 150 mmφ, the uniformity further decreased to ±15%.

The present invention has been made to solve these conventional problems, and aims to provide an ECR plasma processing apparatus that can form a film with extremely good uniformity and that can easily control the film formation. purpose.

[Means for Solving the Problems] The ECR plasma processing apparatus of the present invention that achieves the above object is an ECR plasma processing apparatus that introduces one reaction gas and processes the sample surface by ECR reaction. The present invention is characterized in that it has at least two gas discharge tubes that emit gas to different parts, and some of the gas discharge tubes are provided near the outer periphery of the sample.

[Function] One of the at least two discharge tubes provided in the reaction chamber is located away from the plasma flow, and the reaction gas discharged from here is uniformly distributed within the reaction chamber, and It reacts with plasma and contributes to film formation at a rate proportional to the plasma intensity. That is, the film formation at the center of the sample becomes faster (FIG. 6).

On the other hand, since another discharge tube (1) is installed near the outer periphery of the sample, the reaction gas discharged from this discharge tube reacts with plasma around the sample, accelerating the film formation rate at the sample periphery. Figure 7). A uniform reaction product film is formed on the sample due to the difference in film formation speed between the two methods.

The rate and uniformity of the film produced can be easily controlled by varying the flow rate of gas discharged from each discharge tube.

[Embodiment 1] Hereinafter, a preferred embodiment in which the apparatus of the present invention is applied to an ECR plasma CVD apparatus will be described with reference to the drawings.

The ECR plasma CVD apparatus shown in FIG. 1 has a microwave 11iX1. The device includes a waveguide 2, a discharge chamber 3, and a coil 5, and the discharge chamber 3 is connected to a deposition chamber 7, which is a reaction chamber for performing chemical vapor deposition.

The microwave source 1 is a device that generates microwaves, such as a magnetron, and usually generates microwaves at an industrial frequency (2.45 GHz). The four-wave tube 2 is a metal tube that transmits the generated microwaves, and is provided with microwave wavelength VR adjusting means, mode converting means, reflected wave monitoring section, etc. as necessary. The discharge chamber 3 has a gas introduction pipe 4 that introduces a gas selected depending on the type of film formation, such as N2, O2, Ar, etc., which is a plasma generation source.
are connected, and these gases are introduced at a predetermined flow rate.

Further, a magnetic field in the direction of the electric field is generated within the discharge chamber 3 by the coil 5. The strength of the magnetic field that satisfies the ECR conditions is 2.45
Normally, for example, 875 Gauss for GHz microwave
It is. This magnetic field and microwaves allow charged particles to efficiently absorb electric field energy and generate highly active plasma.

As long as it has this effect, the microwave frequency and the strength of the magnetic field are appropriately selected.

The discharge chamber 3 and the film forming chamber 7 are connected to a vacuum system (not shown) and maintained at a predetermined reduced pressure. For this reason, a sealing member 12 is interposed between the waveguide 2 and the discharge chamber 3 to seal the vacuum and allow the microwave to pass.

Further, the film forming chamber 7 side of the discharge chamber 3 is provided with a microwave reflecting plate 6 so that the microwave resonates within the discharge chamber 3.
A plasma flow is introduced into the film forming chamber 7 through this opening 6a.

The film forming chamber 7 includes a sample stage 8, and a transport mechanism (not shown) is provided to transport the sample W onto the sample stage 8. Further, the film forming chamber 7 is provided with two inlet ports 9 for introducing a reaction gas for film forming, and each inlet port 9 is connected to a ring-shaped gas discharge pipe 10A and IOB, respectively.

The ring-shaped gas discharge tubes 10A and IOB are made of quartz and have a plurality of gas discharge holes 10a on the ring, as shown in FIG.

One of the gas discharge pipes 10A is the other gas discharge pipe 1.
It has a larger diameter than 0B and is installed at a position away from the sample W and the plasma flow P. Further, the other gas discharge tube 10B is installed near the outer periphery of the sample W so as to be in contact with the plasma flow P.

The same type of reaction gas is supplied to these gas discharge pipes 10A and IOH from a supply system (not shown). The reaction gas is silane gas (S iH4) - boron, phosphorus, etc., and argon (Ar).
In some cases, a mixed gas with gas or N2 gas is supplied. The gas flow rate of the reaction gas and the mixing ratio when using a mixed gas are controlled according to the film forming conditions, and in order to obtain uniformity of film forming, these parameters are controlled by adjusting the gas discharge tubes 10A and I
Controlled by OB.

For this reason, an automatically controlled valve 11 is installed in the gas supply system, and the film formation uniformity is measured in advance under predetermined film formation conditions. Both valves can be controlled to take the value of .

Next, the operation of the ECR plasma CVD apparatus having the above configuration will be explained.

First, when the ECR conditions are satisfied in the discharge chamber 3 by the microwave introduced from the microwave source 1 and the magnetic field generated by the coil 5, plasma of the gas introduced from the introduction tube 4 is generated, and a film is formed as a plasma flow P. Flows into room 7. In the film forming chamber 7, reactive gases are released by the gas discharge pipe 10A and IOE and diffused throughout the film forming chamber, and these reactive gases react with the introduced plasma to deposit a reaction product film on the sample surface. At this time, the film formation rate is proportional to the plasma intensity and becomes faster at the center of the sample (Fig. 6), but at the same time, near the periphery of the sample, the gas discharge tube 1. Since the reactive gas is supplied near the plasma and the sample by the OB, deposition at the periphery of the sample W is also promoted (FIG. 7), and as a result, a uniform reaction product film is formed on the sample surface. In this case, the flow rate of the reaction gas introduced from the gas discharge pipe 10A and IOB can be automatically controlled by the valve 11 according to the film forming conditions.

When CVD was actually carried out on silicon wafers using this apparatus, it was possible to obtain film formation uniformity within ±3% on 150 mmφ wafers.

In addition, in the above embodiment, a configuration was shown in which two large and small ring-shaped gas release pipes 10A and 10B were provided as gas release pipes, but the number, size, and shape of the gas release pipes are limited to this embodiment. For example, the gas discharge tube installed at a location away from the plasma does not necessarily have to be ring-shaped, and may be a single tube or other shape. In addition, the gas release tube installed near the sample periphery is not limited to a ring shape, but may also be composed of a quadrilateral gas release tube 10' as shown in FIG. 3 or a plurality of single tubes. It is sufficient if the reaction gas can be supplied near or within the plasma flow.

In particular, in order to increase the film formation rate around the sample, as shown in FIG. It is preferable to install it within the plasma flow P. In the above embodiments, an example of an ECR plasma CVD apparatus has been described, but it goes without saying that any means that generates ECR plasma for processing may be used, such as an etching apparatus.

[Effects of the Invention] As is clear from the above explanation, the ECR plasma processing apparatus of the present invention can greatly improve the uniformity of film formation by changing the supply location of the reaction gas in the film formation chamber. In particular, excellent effects can be achieved on large-diameter wafers.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the device of the present invention, Figs. 2 and 3 each show an embodiment of the reaction gas discharge tube, and Fig. 4 shows another embodiment of the device of the invention. FIG. 5 shows a conventional ECR plasma processing apparatus, and FIGS. 6 and 7 show the film forming speed when the reactant gas supply location is changed. 1...Microwave source 3...Discharge chamber (plasma generation part) 7...
... Film formation chamber (reaction chamber) 10, IOA, IOB ... Reaction gas discharge pipe P.
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Claims (1)

[Claims] An ECR plasma processing apparatus that introduces a reactive gas and processes a sample surface by ECR reaction has at least two gas discharge tubes that discharge the reactive gas to different parts, and some of the gas discharge tubes are arranged around the outer periphery of the sample. An ECR plasma processing apparatus characterized in that it is installed nearby.