JPS61224324A - Dry type thin film processor - Google Patents

Abstract

PURPOSE:To diffuse microwaves on the surface of specimen while making processing effective by a method wherein a metallic vessel encircled with magnetic force line generating means is connected to a reaction tube containing a specimen to vessel or the vessel is provided with electromagnetic shielding sheets with numerous pores in the metallic vessel. CONSTITUTION:Coolers 65 and metallic vessel 63 encircled with solenoids 66 as magnetic force line generating means are connected to the upper part of a reaction tube 69 containing a specimen base 71 whereon a specimen 72 is mounted. Besides, a waveguide 61 is connected to the ceiling of metallic vessel 63 which is fed with N2 gas through the intermediary of a piping 64 while the reaction tube 69 is fed with SiH2 gas through the intermediary of another piping 70 to irradiate the specimen 72 with microwaves through the waveguide 61 for specified processing. In such a constitution, electromagnetic shielding sheets 68 with numerous pores are provided in the metallic vessel 63 to be resonated with the other solenoids 67 encircling the vessel 63 to be resonated with the other solenoids 67 encircling the vessel 63 so that a part of microwaves may be diffused through the pores to disperse the plasma beams reaching the specimen 72.

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

The present invention relates to a thin film processing apparatus for growing a thin film on a semiconductor substrate or etching a thin film on a semiconductor substrate using plasma.

[Prior art and its problems]

Process technology using ECR plasma has recently been attracting attention in the technical field to which this invention pertains. What is ECR?Electron Cyclotron
It is an abbreviation for Re5onance (electron cyclotron resonance), which accelerates electrons using the resonance effect of a magnetic field and microwaves, and uses the kinetic energy of these electrons to ionize gas to obtain plasma. During circular motion, the condition in which centrifugal force and Lorentz force are balanced is called the ECR condition.If zero centripetal force is represented by ω1, and Lorentz force is represented by -erωB, the condition in which both are balanced is ω/B m e / m. It is. Here, ω is the angular velocity of the microwave, B is the magnetic flux density, and e/m is the specific charge of the electron. The frequency of microwaves is generally 45 GHz, which is approved for industrial use, and in that case 0.087
5T (Tesla) is the resonant magnetic flux density. An example of applying ECR plasma to thin film formation is shown in Fig. 2. In this device, the metal container 31 reaction tank 9 is evacuated, and N8 gas is flowed from the gas port 4 into the metal container 3 (not shown). A metal plate 7 having a large diameter hole in the center is attached to the lower part of the metal container 3, which sends microwaves generated by the microwave generating means to the metal container 3 through the waveguide 1 and the vacuum window 2. This metal plate and the metal container 3 constitute a semi-open microwave resonator. A solenoid 6 is disposed outside the resonator, and a magnetic field that satisfies the ECR conditions is generated within the resonator, so that ECR plasma is generated within the resonator. When this plasma is pushed out to the reaction tank 9 and goes to the sample stage 10, silane gas (SiHe) is sent from the gas population 12 into the space and activated by the plasma, the generated active species react with the sample 11 and the sample A thin film is formed on the surface of 11. The mechanism by which plasma is sent out from the large-diameter hole of the metal plate 7 in this conventional device is as follows. An electron moving in a circular motion can be expressed by a magnetic moment μ, and if W is the translational kinetic energy of the electron in the direction of the magnetic field, which has potential energy μH in the magnetic field H, W+μH is the total energy of the electron, which is an adiabatic invariant. Therefore, since electrons have a large W in a place where H is weak, they are naturally accelerated along the lines of magnetic force in the direction of a weak magnetic field. When the electrons are accelerated and shifted, due to the nature of plasma, the ions are also attracted by them and shift in the same direction, creating a plasma flow. In this method, due to its principle, the streamlines of the plasma flow and the lines of magnetic force completely coincide and spread out. Therefore, the distribution of plasma on the sample stage must be uneven, which is compared to the size of the device. However, the disadvantage was that the effective area was extremely small. In order to overcome this drawback, experiments have been carried out to transport the plasma by placing a solenoid outside the reaction chamber without any gaps, as a method to guide the lines of magnetic force straight from the opening of the resonator that generates plasma to the sample 11 or sample stage 10. However, it has many drawbacks, such as the large size of the device, the difficulty in visually observing reactions on the sample surface, and the difficulty in providing a mechanism for handling the substrate, so it cannot be used as a practical device.Next For example, the reactive ion beam etching method shown in Fig. 3 is known as an etching device that applies the ECR effect.
The ion extraction electrode 27 extracts the generated ions into the reaction chamber 29, obtains a parallel ion beam, and irradiates the sample 31 with the ion beam. The aim is to obtain etching with high directionality in the direction of movement, that is, high anisotropy.The beam obtained at this time is a beam of only unipolarity (usually positive polarity), and among the effective active species, only those with opposite polarity are used. (usually negative ions).Also, in order to avoid spreading the beam due to the repulsive force between ions, a medium is placed between the ion extraction electrode and the sample to emit electrons to neutralize the ions. Usually, particles are neutral when they reach the sample surface, which means that the unique activity of ions cannot be utilized and the etching rate is low. A large electric field is required to extract the ions, and it is difficult to adjust the speed of particles and particles, especially in the low speed range, so the damage to the sample cannot be ignored.
The method shown in the figure is known. In this method, microwaves generated by a magnetron 41 are injected into the internal space of a quartz tube 44 through waveguides 42 and 43.
The internal space of the reaction tank 47 is evacuated in advance,
A source gas is caused to flow here through a gas port 46, and when an ECR condition is established in the internal space of the quartz tube 44, the gas is turned into plasma by a solenoid 45. This plasma is sent out from the interior space of the quartz tube 44 to the interior space of the reaction tank 47 using the same principle as previously explained for the thin film forming apparatus, and reaches the sample 49 placed on the sample stage 48. The active species react with the surface of the substrate 49, and etching progresses. If necessary, a permanent magnet is placed under the sample stage 48 to allow the plasma to be transported to the sample. In this method, the lines of magnetic force trace a curve before arriving at the sample, making it difficult for the density of the transported plasma to be uniform.
The disadvantage is that the etching speed varies on the same sample surface. Furthermore, in this method, the microwave directly hits the sample, so the resist is heated and damaged due to dielectric loss. Damage to the circuit formed on the sample surface cannot be ignored because the plasma comes into direct contact with the sample.

[Purpose of the invention]

This invention eliminates the drawbacks of the conventional apparatus using microwave ECR plasma as described above, realizes a large diameter, uniform and parallel plasma flow in a simple manner, and produces high quality and uniform thin films.
It is an object of the present invention to provide a semiconductor manufacturing apparatus for realizing etching that is uniform, without damage, and in which active species can be used without waste.

[Key points of the invention]

In this invention, when a part of the ECR plasma generation container is constituted by an electromagnetic shielding plate having a large number of small holes and having microwave shielding ability, plasma is drawn out in the direction of the gradient of the lines of magnetic force at the position of the shielding surface of the electromagnetic shielding plate. This is based on the inventor's experimental findings. Although there is no other report on this phenomenon, according to the inventor's theoretical considerations, the causes of this phenomenon are as follows. Before we get into the explanation, let us find the magnitude of the magnetic moment of an electron moving in a circular motion (the radius of the circular motion of an electron is determined by the maximum value of the electric field produced by the microwave, and if this is E, then e E. It is calculated as m ω2. If the power density of the electromagnetic wave is p [W/m”], then the effective value E of the electric field is given by where Z is the characteristic impedance of the space of 120π ohm. Therefore, if the power density of the microwave is determined, the electric field can be found.Now, the diameter is 0.125.
If a microwave of 200 W is injected into a resonator of m, E = 2478.8 [V/m], Ep
-L[E -3505,5[V/m] Therefore e E. m ω2 −1.758796xlO” [C4g-breath] 350
5.5 [V/m] × -2,66 [μm] Therefore, the magnetic moment is I"6μorω/2 -1.6 XIG-" [Coulomb] ×4πXIQ
-', [H/II]X2.66 [μm]×2πX
2.45XIO"[3-'] XW-4,077X
10-Snow' [Wb-m]. Now, to explain the phenomenon, with the conventional device mentioned earlier, μ,
It is assumed that H + W is constant and energy is exchanged between μH and W, but intuitively, the direction of the magnetic moment and the magnetic field are opposite and the magnetic guipole is pushed along the magnetic field. It is. This state persists in a space where microwave energy is supplied, but when the magnetic Guipole moves out of the microwave area, a force acts to align the magnetic moment with the direction of the magnetic field, causing the Guipole to rotate. When the lines of magnetic force are perpendicular to the guipoles, the Lorentz force does not act on the electron at all, and only the centrifugal force acts, and the electron leaves the magnetic line of force and flies out.
It no longer produces circular motion. The energy number of electrons due to centrifugal force at this time is %m(r
ω) Since it is small at 7,54 x 10 -1t joules - 4,713 millielectron volts, the movement of electrons proceeds in the direction of translational movement, that is, in the tangential direction of the lines of magnetic force. The energy of this progression is μ(
Htc*-Hoot) and I(act is ECR
The strength of the magnetic field of the loincloth (root) is the strength of the magnetic field at the position of the shielding surface of the electromagnetic shielding plate. Therefore, depending on the magnitude of Hoot, the speed of the electrons is adjusted steplessly up to a maximum of μHzcm. Now, when we calculate μI(In under the conditions of the microwave power density and the resonator diameter used earlier, #H-4,077Xl0-" [Wb-ml '0
．． 0875 [T] 4πxlO-' [H/s] -41770 electron volts, and it can be seen that the initial velocity of the electrons can be adjusted over a very large range by adjusting Hoot. Furthermore, since this is not an electron extraction due to an electric field, it is interpreted that the ions can be thrown out along the way and emitted in the direction of plasma. The gist of the present invention is to utilize this phenomenon to create and apply a new plasma extraction mechanism. The microwave is introduced into the metal container, and a part of the metal container is made up of an electromagnetic shielding plate that has a large number of small holes and does not allow the introduced microwave to pass through to the other surface, and a magnetic field line is formed in the metal container. a first magnetic field line generating means that generates a single active atom molecule or ion by turning the gas introduced into the metal container into plasma due to the resonance effect with the microwave, and substantially perpendicular to the shielding surface of the electromagnetic shielding plate. a second magnetic line of force generation means for generating intersecting lines of magnetic force and controlling at least one of the speed and direction of electrons that leak out of the metal container through the small hole of the electromagnetic shielding plate, The above object is achieved by drawing the ions constituting the plasma out of the metal container by the controlled attraction of electrons, and generating a plasma flow with controlled speed or spread outside the metal container. That is.

[Embodiments of the invention]

FIG. 1 shows an embodiment of the present invention, in which a solenoid 67 and an electromagnetic shielding plate 68 having a large number of small holes are added in addition to the conventional method shown in FIG. The solenoid 66 is for generating an ECR magnetic field. By adjusting the height or axial position of the solenoid 67 and the current, the angle between the lines of magnetic force and the shielding surface of the electromagnetic shielding plate and the strength of the magnetic field are changed. When a parallel plasma flow is required, the angles should be set at right angles, when an expanded beam is required, the magnetic field lines should be spread out, and when a contracted beam is required, the magnetic field lines should be set so that they intersect at a contracting gradient. Similarly, by adjusting the strength of the magnetic field, the initial velocity of the plasma flow is adjusted to the optimal value. In addition, 65 in the figure
is a cooling pipe provided on the outer wall of the metal container 63 through which a refrigerant for cooling the metal container wall passes.

【Effect of the invention】

As described above, according to the present invention, the container for generating ECR plasma using microwaves is made of metal, and a part of the metal container is provided with a large number of small holes that have a microwave shielding effect. Consisting of an electromagnetic shielding plate, at least one of the direction and magnitude of magnetic lines of force that intersect with the shielding surface of the electromagnetic shielding plate are variable, and the magnetic lines of force leak out of the metal container through small holes in the electromagnetic shielding plate. In addition to controlling the direction or speed of the electrons, the ions that make up the plasma inside the metal container are drawn out of the container by the attraction force of the controlled electrons, so that a large-diameter, uniform, parallel beam is placed outside the metal container. A plasma flow can be easily obtained, and the flow rate of this plasma flow can also be controlled. As a result, it has become possible to create a thin film processing apparatus that can manufacture high-quality, uniform thin films, or perform etching processing that is uniform, undamaged, and can utilize nine active atoms or ions without wasting them.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of a dry thin film processing apparatus constructed based on the present invention, and FIG.
Vertical cross-sectional view of an example of a thin film production device using CR plasma, No. 3
The figure is a longitudinal sectional view of an example of an ion beam etching apparatus using conventional microwave ECR plasma, and FIG. 4 is a longitudinal sectional view showing another example of an etching apparatus using conventional microwave ECR plasma. 1.21.41.61 : Waveguide, 3.23.63
: Metal container, 11.31.49.72 : Sample, 66:
1st line of magnetic force generating means, 67: second line of magnetic force generating means. Micro flow IF5 diagram ↓ Tenkubo No. 21! f My Flora friend! , Kent Figure 3

Claims (1)

[Claims] 1) means for generating microwaves; means for transmitting the microwaves; A metal container partially constituted by an electromagnetic shielding plate that does not allow the introduced microwaves to pass through to the other surface, and magnetic lines of force generated within the metal container that are introduced into the metal container due to the resonance effect with the microwaves. a first magnetic field line generating means that generates active atoms, molecules or ions by converting gas into plasma; and a first magnetic field line generating means that generates magnetic field lines that intersect substantially perpendicularly to the shielding surface of the electromagnetic shielding plate and passing through the small holes of the electromagnetic shielding plate to the metal container. a second magnetic field line generating means for controlling at least one of the speed and direction of the electrons penetrating outward; A plasma flow with controlled velocity or spread is generated outside the metal container by drawing it out of the metal container, and active atoms, molecules, or ions contained in this plasma flow are used to form a thin film on the surface of the sample or to etch it. Dry thin film processing equipment that performs processing. 2) In the device according to claim 1, second magnetic force line generating means for controlling at least one of the speed and direction of electrons leaking out of the metal container is arranged surrounding the metal container. A dry thin film processing device characterized by a solenoid installed. 3) A dry thin film processing apparatus according to claim 2, wherein the solenoid, which is the second magnetic force line generating means, is disposed so as to be movable in the axial direction thereof.