JPH02308535A - Plasma treatment apparatus for forming compound thin film - Google Patents

Abstract

PURPOSE:To form a high quality compound film by a method wherein gases which are produced in a plasma generating chamber and an evaporation source chamber and not necessary for forming the film are removed and a plasma particle flow and an evaporation atom flow are formed through a fine holes provided between the plasma generating chamber and a reaction chamber and between the evaporation source chamber and the reaction chamber respectively. CONSTITUTION:A plasma generating chamber 4, an evaporation source chamber 20 and a reaction chamber 5 are evacuated in a differential manner to eliminate most of raw gases or rare gases which do not contribute to plasma generation from a plasma generation in the generating chamber 4 by an evacuation pump 8. At the same time, charged particles, active species and plasma lights in the plasma are made to flow through the fine hole 13a of a conical skimmer 13 into the reaction chamber 5 maintained in a high vacuum state and reach a work substrate 15 on a substrate holder 14. On the other hand, an evaporated atom flow from the evaporation source chamber 20 are made to flow through the fine hole 22a of a conical skimmer 22 into the reaction chamber 5 maintained in a high vacuum and guided to the work substrate 15 on the substrate holder 14.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a plasma processing apparatus for forming compound thin films using microwaves, and in particular, to a plasma processing apparatus suitable for forming compound thin films on substrates such as semiconductors and insulators. This invention relates to plasma processing equipment.

[Conventional technology]

In recent years, dry processes using plasma have become popular as a thin film forming technology in processes such as semiconductor device manufacturing, and C
It has been adopted as a low-temperature film formation technology in place of the VD method.

For example, since plasma CVD is used for surface modification, there are a wide variety of film forming methods such as ion nitridation, and a wide range of film forming targets.

・This low-temperature plasma process uses electron cyclotron resonance (ECR) to obtain plasma to form a film, and it is possible to generate plasma at low pressure, resulting in a high film growth rate and the risk of contamination with impurities. It is expected that uniform film formation will be possible.

Conventionally, activated reactive vapor deposition is a low-temperature film formation technology that uses plasma, but by using ECR, it is possible to reduce the generation of impurities contained in the formed thin film. Are known.

For example, in JP-A No. 61-135126, an ECR plasma is used as an activated ion source, the evaporation source is placed in a position that avoids the influence of the ECR plasma flow, and the atomic flow and plasma of the evaporation source in the same vacuum container are It has been described that a uniform thin film with few impurities can be formed on a working substrate by the irradiation effect of charged particles.

[Problem to be solved by the invention]

In conventional plasma processing equipment for compound thin film formation using microwaves of this kind, since the plasma generation source and the evaporation source are placed in the same vacuum container, mutual interference between the plasma generation source and the evaporation source is avoided. cannot be avoided.

In particular, when it is expected to form a high-quality thin film using plasma generated in a low pressure region of 10-' Torr or less, for example, the work substrate or vacuum system may be Contamination and charged particles of said impurities and plasma.

Interference with active species, reaction, and contamination will occur.

The present invention separately evacuates the plasma generation source chamber containing the plasma generation source and the evaporation source chamber containing the evaporation source in addition to the reaction chamber in which the work substrate is placed, thereby preventing the occurrence of contamination due to mutual interference between the respective chambers. Avoid as much as possible and prevent contaminants from entering the reaction chamber.
It is an object of the present invention to provide a plasma processing apparatus for forming a compound thin film, which is equipped with means for accurately flowing charged particles and active species from a plasma source chamber and metal atoms from an evaporation source chamber into a reaction chamber.

[Means to solve the problem]

In order to achieve the above object, the present invention turns one elemental gas of raw material gases into plasma in a plasma generation chamber using an electron cyclotron resonance method, irradiates a work substrate in a reaction chamber, and evaporates metal 9 alloy. In a plasma processing apparatus, a flow of metal atoms from a source chamber is directed toward a work substrate, and a reaction product of plasma particles and evaporated metal is formed as a thin compound film on the surface of a work substrate provided in the reaction chamber. A vacuum evacuation means is provided in each of the source chambers separately from the evacuation means for the reaction chamber, and gases unnecessary for thin film formation generated in the plasma generation chamber and the evaporation source chamber are removed, and the plasma generation chamber, the evaporation source chamber, and the reaction chamber are It is characterized by forming a plasma particle flow and an evaporated atom flow through the pores provided between the two.

[For production]

According to the configuration of the present invention, each of the plasma generation source chamber containing the plasma generation source and the evaporation source chamber containing the evaporation source is evacuated separately from the reaction chamber in which the work substrate is arranged, thereby preventing contamination due to mutual interference between the respective chambers. This prevents contaminants from flowing into the reaction chamber as much as possible, and allows charged particles and active species to flow accurately into the reaction chamber from the plasma source chamber and metal atoms from the evaporation source chamber. can form a high-quality thin film.

〔Example] Embodiments of the present invention will be described below based on the drawings.

FIG. 1 shows a plasma processing apparatus comprising activated reactive vapor deposition using plasma generated by electron cyclotron resonance (ECR).

3 is a microwave ordering device, and the microwave generated by the microwave generator 1 passes through waveguides 2a, 2b, 2c, and 2d to a plasma generation chamber 4 surrounded by electromagnets 3a to 3d.
guided by. The plasma generation chamber 4 is formed at one end of the reaction chamber 5 which is the main body of the vacuum container, and the plasma generation chamber 4 is supplied with a raw material gas or a rare gas for generating electric discharge in a predetermined manner by a gas supply device 6 and a mass flow controller 7. N
The plasma generation chamber 4 is pumped with an exhaust pump 8. A predetermined pressure is maintained by a variable conductance valve 9. The exhaust pump 8 uses a high vacuum exhaust pump with a relatively small exhaust capacity, such as a turbo molecular pump. 10 is an auxiliary valve, and 11 is an auxiliary pump.

Microwaves are transmitted from the microwave waveguides 2a to 2d to the quartz window 1.
2 to the plasma generation chamber 4, plasma is generated by the action of the electromagnets 3a to 3d, which are air-core magnetic field coils, and most of the source gas or rare gas that does not participate in plasma generation is removed by the exhaust pump. 8 is excluded. Charged particles, active species, and plasma light in the plasma generated in the plasma generation chamber 4 are transferred to the pores 13 of the cone-shaped skimmer 13.
The liquid flows into the reaction chamber 5 set in a high vacuum state through the tube a, and reaches the work substrate 15 on the substrate holder 14 disposed in the reaction chamber 5. The cone-shaped portion of the skimmer 13 is made of a high dielectric constant material such as quartz or alumina ceramics, and has a structure that can be water cooled.

In order to establish a high vacuum state in the reaction chamber 5 in which the work substrate 15 is placed, a main pump 16, which is a vacuum pump having a high pumping speed, is provided via a main valve 17. The pressure in the reaction chamber 5 is precisely controlled by a variable conductance valve 18.

A permanent magnet 19 is provided at a position facing the plasma particle flow jetting into the reaction chamber 5 so as to be able to move toward and away from the work substrate 15.
The spread of the plasma particle stream can be changed.

An evaporation source chamber 20 is provided on the bottom side of the reaction chamber 5 in order to provide a work substrate 15 provided in the reaction chamber 5 with an evaporation atom flow perpendicular to the plasma particle flow. The evaporation source chamber 20 includes an evaporation source such as an electron beam evaporation source, is connected to a high vacuum evacuation pump 21 such as a turbo molecular pump, and is evacuated to a vacuum state.

A cone-shaped skimmer 22 is located between the evaporation source chamber 20 and the reaction chamber 5, and the evaporated metal flow in the evaporation source chamber 20 is jetted into the reaction chamber 5 through the pores 22a of the skimmer 22.
A trumpet-shaped shielding plate 23 is positioned to guide the vaporized atom flow to the work substrate 15.

In the drawing, 24 is an auxiliary pump, 25 is an evaporation source homeowner valve, 26 is a reaction chamber roughing valve, 27 and 28 are auxiliary valves, 29 to 31 are vacuum gauges, 32 is an evaporation source roughing valve,
33 indicates a plasma flow, and 34 indicates an evaporated atom flow.

Although not shown, the plasma generation chamber 4 and the reaction chamber 5
During this period, a shutter is provided between the reaction chamber 5 and the evaporation source chamber 20, respectively. By using a cryopump as the main pump 16, after starting up the main pump, the auxiliary pump 2
4 is used exclusively for rough evacuation of the reaction chamber 5 and the evaporation source chamber 20, and after the rough evacuation is completed, the evaporation source chamber 20 is used as an auxiliary evacuation for the evacuation pump 21 for vacuum evacuation.

Also, a skimmer 13 provided between the plasma generation chamber 4 and the reaction chamber 5. The skimmer 22 provided between the evaporation source chamber 20 and the reaction chamber 5 has different pore shapes and pore diameters, and can be attached interchangeably.

In the present invention, a main pump 16 for high vacuum evacuation is provided in the reaction chamber 5.
, the plasma generation chamber 4 and the evaporation source chamber 20 are each equipped with high vacuum pumps 8 and 21, and the pressure in the plasma generation chamber 4 is set to, for example, lXl0-2Pa, and the pressure in the evaporation source chamber 20 is lXl0-” below lXl0-”Pa
3 Pa, and the reaction chamber 5 can be maintained at 1×1 O −5 Pa, which is a high vacuum state suitable for vacuum evaporation.

By differentially pumping each chamber, most of the raw material gas or rare gas that does not participate in plasma generation in the plasma generated in the plasma generation chamber 4 is removed by the exhaust pump 8, and the plasma generated in the plasma generation chamber 4 is charged particles, active species,
The plasma light is transmitted through the pores 13a of the cone-shaped skimmer 13.
is jetted into the reaction chamber 5 set in a high vacuum state through the
Work substrate 1 on substrate holder 14 placed in reaction chamber 5
Reach 5.

Also, due to the constraints in the evaporation source chamber 20, the above-mentioned vacuum state is set, and unnecessary particles other than the evaporated atomic mass with high thermal energy are evacuated by the vacuum exhaust pump 21, and the evaporated atomic flow is passed through the cone-shaped skimmer 21. The liquid can be jetted into the reaction chamber 5 set in a high vacuum state through the pore 21a and guided to the work substrate 15 on the substrate holder 14 disposed in the reaction chamber 5.

FIG. 2 shows a diagram of the principle of differential pumping between two chambers.

A baffle plate 37, which is a skimmer with an orifice formed therein, is located between the two vacuum vessels 35 and 36. The pore diameter of the orifice is d [m], and two vacuum vessels 35
．． 36 are provided with respective vacuum pumps, and the exhaust pressure of the vacuum container 35 is maintained at Po (Pa). The vacuum container 36 is also evacuated by a vacuum pump, and its effective pumping speed is assumed to be Se (m3/S). In this case, the vacuum container 35
Let Q (Pa-m3/s) be the amount of gas that steadily flows through the pore diameter of the vacuum vessel 36 orifice. The vacuum vessel 36 is evacuated by a vacuum pump giving an evacuation speed Se, and the evacuation pressure is P.

(Pa), when the amount of gas released from the wall of the vacuum container is extremely small compared to the amount of gas in a steady flow, it is expressed by the following equation.

Q=C(P, -P,).

P,=Q/Se.

Therefore, 5e-P, =C(Po P+).

Here, C is an orifice (
is the conductance of the pore), and C is 116A
(m3/s).

All of these equations hold true for the molecular flow region of gas flow.

Now, Pa-1X1O-” (Pa).

5e=0.5 (m″/sl.

If d-8X 10-' (m), P+ = 4.6
X10-'(Pa).

Therefore, by using the vacuum container 35 as the plasma generation chamber 4 or the evaporation source chamber 20 and the vacuum container 36 as the reaction chamber 5, a differential pumping configuration can be obtained.

FIG. 3 shows an example of a specific configuration of the skimmer 13 located between the plasma generation chamber 4 and the reaction chamber 5 shown in FIG. 1.

The plasma generation chamber 4 and the reaction chamber 5 must be hermetically isolated by the skimmer 13, and the skimmer 13 must be detachably attached while maintaining insulation from the wall of the reaction chamber 5.

By insulating a portion of the gap from the wall of the reaction chamber, it is possible to avoid affecting the flow of charged particles in the plasma.

For this reason, the inner wall 38 between the plasma generation chamber 49 and the reaction chamber 5
A skimmer is attached to the insulating joint 39. The insulating joint 39 is equipped with vacuum flanges 39b and 39c on both sides of a ceramic material 39a such as alumina, one vacuum flange 39b is supported by the inner wall 38 via a metal hollow ring 40, and the other vacuum The flange 39C is a metal flange 41 formed in the gap part 41.
C via a metal gasket 42.

The gap portion 41 includes a cone-shaped portion 41b made of a high dielectric material such as alumina with a pore 41a formed in the center.
The metal flange 41C is provided at the end of 1b to suppress absorption and reflection of electromagnetic waves. 43 is a water cooling pipe provided near the vacuum flanges 39b, 39c of the insulating joint 39 and the metal flange 41c of the gap part 41, and is designed to suppress local heat generation due to microwaves and heat generation due to plasma flow irradiation. I can do it.

The gap portion 41 can change its shape depending on the manner in which the plasma flow is sent to the reaction chamber, and is detachably attached.

The shape of the pores 41a of the gap portion 41 may be of various shapes other than circular. In order to draw out the plasma flow generated in the plasma generation chamber 4 into the reaction chamber 5, the spread of the plasma flow is controlled by changing the position of the permanent magnet in the reaction chamber 5. Shapes can be selected and controlled.

An example of the shape of the pores is shown in FIGS. 4(a) and 4(b). The pores in the case of FIG. 4(a) include a central circular pore 44 and a plurality of slits 4 radiating from the circular pore 44.
The pores in the case of FIG. 4(b) consist of a central circular pore 44 and a plurality of micropores 46 of several tens of microns around the circular pore 44. In relation to the shape of the board,
The plasma flow can be uniformly irradiated onto the substrate surface due to the effect of the pore shape and the magnetic field of the permanent magnet.

FIG. 5 shows the evaporation source chamber 20 and reaction chamber 5 shown in FIG.
This is an example of a specific configuration of the skimmer 22 located between the two.

The evaporation source chamber 20 and the reaction chamber 5 are hermetically isolated by a skimmer 22 to prevent unnecessary diffusion of the evaporated atom flow ejected from the skimmer 22 to the reaction chamber 5. Moreover, the skimmer 22 is used when changing the sample used, etc. Since it must be replaced and cleaned at the time of use, it must be removably attached to the wall.

Therefore, a metal flange 47c of the gap portion 47 is removably attached to a metal flange 38a attached to the inner wall 38 between the evaporation source chamber 209 and the reaction chamber 5 via a metal gasket 48.

The gap portion 47 includes a cone-shaped portion 47b made of a metal material with a pore 47a formed in the center, and a metal flange 47C is provided at the end of the cone-shaped portion 47b.

A shielding plate 49 extending into a cylindrical shape is supported by the inner wall 38 so as to surround the gap portion 47. The shielding plate 49 is used to exhaust the space located between the shielding plate 49 and the gap portion 47. An exhaust hole portion 49a is provided in the exhaust hole portion 49a. 50 is a welding part.

〔effect〕

In the configuration of the present invention, a predetermined exhaust pressure is obtained by exhausting the reaction chamber, the plasma generation chamber, and the evaporation source chamber, respectively, and the plasma generation chamber and the reaction chamber are evacuated.

By installing a cone-shaped skimmer between the evaporation source chamber and the reaction chamber, the working substrate of the reaction chamber can be
A good compound thin film can be formed by reducing the influence of mutual interference from the evaporation source chamber. That is, a reaction chamber,
Due to the royal differential exhaust in the plasma generation chamber and evaporation source chamber, gas molecules that are not involved in plasma generation out of the raw material gas injected into the plasma generation chamber can be directly exhausted and removed within the plasma generation chamber. Prevents non-participating gas molecules from diffusing into the reaction chamber and evaporation source chamber,
As a result, the influence on the working substrate 2 reaction chamber wall and the heating source in the evaporation source chamber can be reduced, and impurities from the crucible material and filament can be directly exhausted from the evaporation source chamber as well, preventing them from diffusing into the reaction chamber. This can prevent backflow to the plasma generation chamber.

Furthermore, compared to the case where the reaction chamber is evacuated using a single conventional exhaust pump, a high vacuum can be obtained with fewer unnecessary particles, and a good compound thin film can be formed.

[Brief explanation of drawings]

Figure 1 is a schematic cross-sectional view of the plasma processing apparatus for forming compound thin films of the present invention, Figure 2 is an explanatory diagram showing the principle of differential pumping, and Figure 3 is the installation of a skimmer between the plasma generation chamber and the reaction chamber. 4 is a front view of the pore shape of the skimmer shown in FIG. 3, and FIG. 5 is a sectional view of the part where the skimmer is installed between the evaporation source chamber and the reaction chamber. 4... Plasma generation chamber, 5... Reaction chamber, 6... Gas supply device, 8... Exhaust pump for plasma generation chamber, 1
3... Skimmer, 15... Work board, 16... Exhaust pump for reaction chamber, 20... Evaporation source chamber, 21... Exhaust pump for evaporation source chamber, 22... Skimmer, 33...・・・
Plasma flow, 34... Evaporated atom flow.

Claims (1)

[Claims] In the plasma generation chamber, one of the elemental gases in the raw material gas is turned into plasma using the electron cyclotron resonance method and irradiated onto the work substrate in the reaction chamber. At the same time, a flow of vaporized atoms from the evaporation source chamber that evaporates metals and alloys is directed onto the work substrate. In a plasma processing apparatus that forms a reaction product of plasma particles and evaporated metal as a thin compound film on the surface of a work substrate provided in a reaction chamber, a reaction chamber evacuation means is provided in each of the plasma generation chamber and the evaporation source chamber. Separately, a vacuum evacuation means is provided to remove unnecessary gas for thin film formation generated in the plasma generation chamber and evaporation source chamber, and to remove gas unnecessary for thin film formation from the plasma generation chamber and evaporation source chamber through the pores provided between the plasma generation chamber and evaporation source chamber and the reaction chamber. plasma particle flow,
A plasma processing apparatus for forming a compound thin film, which is characterized by forming an evaporated atomic flow.