JPS6380842A - Reaction using fine particle - Google Patents

Abstract

PURPOSE:To reduce damage due to the collision of charged particles having large charge, by forming an electric field to the flow passage of the activated raw gas being the jet stream substance from a contracting and expanding nozzle and selectively sending the neutral particles in the raw gas to a reaction field. CONSTITUTION:When the downstream chamber 4 is evacuated while raw gas A is supplied into the upstream chamber 3, the raw gas A is injected to the downstream chamber 4 through a contracting and expanding nozzle 1. When the raw gas A is injected in a definite direction as a proper expanded stream of supersonic velocity, the raw gas A after injection straightly advances in the min. diffused state to be formed into beam stream. When the beam stream of this activated raw gas A enters the electric field due to an electric field forming means 2, the particles having charge in the beam stream receive the effect of said electric field. However, since neutral particles receive no effect of the electric field, said particles straightly advance as they are while are distinguished from the charged particles receiving the effect of the electric field to be sent to a reaction field.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to, for example, film forming processing, etching, doping processing,
This invention relates to a reaction method used in treatments such as surface modification, and more specifically, relates to a reaction method in which activated raw material gas is sent as a beam stream to a reaction field where the treatment described in L is performed.

[Prior Art] Ion implantation technology is conventionally known as a reaction method in which activated source gas is sent as a beam stream to a reaction field. In this ion implantation technology, raw material gas is actively ionized, accelerated by an electric field, and supplied to a reaction field as a single stream.

[Problems to be Solved by the Invention] Incidentally, in the above-mentioned conventional reaction method, the flow of active ions is converted into a beam stream using an electric field, so it is charged particles that are converted into a beam stream. Therefore, there is an unavoidable problem in that charged particles having a large charge collide with the object to be processed, such as film formation or etching, resulting in damage.

[Means for solving the problems] The means taken to solve the above problems will be explained with reference to FIG. 1, which corresponds to an embodiment of the present invention.
An electric field is formed in the flow path of the activated raw material gas sent as a jet stream from the contraction/expansion nozzle l, and neutral particles in the activated raw material gas are selectively sent to the reaction field. This method uses microparticles as a reaction method.

In the present invention, the contracting/expanding nozzle 1 is defined as having an opening area gradually narrowed from an inlet la toward an intermediate portion to form a throat portion 1b, and an opening area gradually expanding from this throat portion toward an outlet port 1c. Refers to the nozzle that is present. The gas includes not only gases but also those that can be transported substantially as a gas phase flow, such as fine particles. Moreover, neutral particles refer to atoms, molecules, clusters, and other fine particles that have no electric charge.

[Function] In FIG. 1, when the downstream chamber 4 is evacuated while the raw material gas A is supplied into the upstream chamber 3, the raw gas A is ejected into the downstream chamber 4 through the contraction/expansion nozzle 1. become.

The contraction/expansion nozzle 1 can speed up the flow of the source gas A to supersonic speed by setting the pressure ratio P/Po of the pressure PO in the upstream chamber 3 and the pressure P in the downstream chamber 4 to a critical pressure ratio or less.

Here, the critical pressure ratio means the following value. That is, when the flow velocity of the raw material gas A at the throat section 1b of the contraction/expansion nozzle 1 matches the sonic velocity, the flow velocity at the outlet port 1c ideally matches the throat section 1b.
Opening area ratio A between the cross-sectional area A◆ and the cross-sectional area A of the outlet 1c
It corresponds to the Matsuha number M determined by /A. This relationship is specifically determined by equation (3), which will be described later. Then, for such a Matsuha number M, the pressure ratio P/P O between the pressure Po in the upstream chamber 2 and the pressure P in the downstream chamber 3 determined by the following equation (1) is called the critical pressure ratio. is the specific heat ratio of raw material gas A.

Here, if we assume that the velocity of the raw material gas A is U, the sound velocity at that point is a, and that the raw material gas A expands adiabatically in a compressible one-dimensional flow, the Matsuh number M reached by the raw material gas A is It is determined by the following equation from the pressure Po and the downstream pressure L', and especially when P'/Po is less than the critical pressure ratio, M becomes 1 or more.

Note that the sound velocity a can be determined by the following equation, where T is the local temperature and R is the gas constant.

a='71]7 Further, the following relationship exists between the opening surface IA of the outlet 1c and the opening area A° of the throat portion 1b and the Matsuhah number M.

Therefore, by adjusting the pressure ratio P/Po to the critical pressure ratio according to M determined from equation (3) by the opening area ratio A/A, the raw material gas A ejected from the expansion/contraction nozzle 1 is
can be ejected as an appropriately expanded flow at a sonic speed.

Here, the expansion of the raw material gas A when the pressure ratio of the upstream chamber 3 and the downstream chamber 4 is equal to the critical pressure ratio is referred to as proper expansion. In addition, the velocity U of the raw material gas A at this time is as follows (4
) can be obtained using the formula.

Here To is the gas temperature in the flow chamber.

When the raw material gas A is ejected in a fixed direction as a properly expanded flow at supersonic speed as described above, the raw material gas A travels straight with minimal diffusion after being ejected, and becomes a beam.

Therefore, by activating the raw material gas A, a beam flow of the activated raw material gas A can be created.

On the other hand, when the beam flow of the activated raw material gas A enters the electric field generated by the electric field forming means 2, charged particles in the beam flow are influenced by this electric field. However, since the neutral particles are not affected by the electric field, they are separated from the charged particles, which are affected by the electric field, and proceed straight as they are and are sent to the reaction field. Therefore, only uncharged neutral particles can be sent to the reaction field.

[Example] A waveguide 6 is connected to the upstream chamber 3 to which the raw material gas A is supplied via a window 5 formed of a material that can transmit microwaves, such as quartz. The waveguide 6 is for introducing microwaves into the upstream chamber 3 through the window 5.
The raw material gas A is activated within the upstream chamber 3 by cyclotron resonance.

The upstream chamber 3 is communicated with the downstream chamber 4 via the contraction/expansion nozzle 1 .

As mentioned above, the inflow meter 1a is used as the contraction/expansion nozzle 1.
It is sufficient if the opening area is gradually narrowed down to 1lb, and the opening area is gradually expanded again to form the outlet 1c, but it is shown enlarged in Fig. 2(a). As shown in the figure, it is preferable that the inner circumferential surface is substantially perpendicular to the central axis at the outlet IC position. This is because the flow direction of the ejected raw material gas A is influenced to some extent by the direction of the inner circumferential surface of the outlet 1c, so that it is possible to make the flow parallel to each other as easily as possible. However, as shown in FIG. 2(b), if the angle α of the inner peripheral surface from the throat portion 1b to the outlet IC with respect to the central axis is set to 7 degrees or less, preferably 56 or less, the peeling phenomenon is less likely to occur. Since the flow of the ejected raw material gas A is maintained almost uniformly, in this case it is not necessary to make it parallel as described above, and by omitting the formation of the flowing part, it is easy to manufacture the contracting and expanding nozzle L. becomes. Furthermore, if the contraction/expansion nozzle 1 is made rectangular as shown in FIG. 2(C), the raw material gas A can be ejected in a slit shape.

Here, the separation phenomenon is a phenomenon in which when there is a protrusion or the like on the inner surface of the contraction/expansion nozzle 1, the boundary layer between the inner surface of the contraction/expansion nozzle 1 and the flowing fluid becomes large and the flow becomes non-uniform. The faster the jet flow, the more likely it is to occur. In order to prevent this peeling phenomenon, the above-mentioned angle α is preferably made smaller as the inner surface finishing precision of the contraction/expansion nozzle 1 is inferior. The inner surface of the contraction/expansion nozzle 1 conforms to JIS 8060.
1, three or more inverted triangular marks representing surface finish accuracy, most preferably four or more -42. In particular, since the peeling phenomenon in the enlarged part of the contraction/expansion nozzle 1 greatly affects the subsequent flow of the raw material gas A, by determining the finishing accuracy with emphasis on this enlarged part, the fabrication of the contraction/expansion nozzle 1 is improved. It's easy to do. Furthermore, in order to prevent the occurrence of a peeling phenomenon, the throat portion 1b must have a smooth curved surface so that the differential coefficient in the rate of change in cross-sectional area does not become (3).

The material of the contraction/expansion nozzle 1 can be widely used, such as iron, stainless steel, and other materials, as well as synthetic resins such as acrylic resin, polyvinyl chloride, polyethylene, polystyrene, and polypropylene, ceramic materials, and glass. Can be done. This material may be selected by taking into consideration non-reactivity with the raw material gas A, workability, gas release properties in a vacuum system, etc. It is also possible to plate or coat a material that does not easily cause Specific examples include polyfluoroethylene coating.

The length of the contraction/expansion nozzle 1 can be arbitrarily determined depending on the size of the device and the like. By the way, contraction/expansion nozzle 1
When flowing through the source gas A, the thermal energy it possesses is converted into interlocking energy. Particularly when ejected at supersonic speed, the thermal energy is significantly reduced and a cooling state occurs. Therefore, when the carrier gas contains catenary components, it is also possible to actively condense them by the above-mentioned cooling state, thereby forming fine particles. Further, in this case, it is preferable that the contraction/expansion nozzle 1 is long in order to perform the above condensation. On the other hand, when condensation occurs as described above, thermal energy increases and velocity energy decreases. Therefore, in order to maintain high-speed jetting, it is preferable that the contraction/expansion nozzle 1 be short.

In the downstream chamber 4, a pair of electrodes are provided as electric field forming means 2, with a flow path for raw material gas A ejected from the L contraction/expansion nozzle 1 interposed therebetween. Moreover, this electric field forming means 2
A substrate 7 to be treated is provided on the downstream side of the substrate. Furthermore, raw material gas B is supplied to the vicinity of the front surface of this base body 7.

In this embodiment, the source gas A is activated in the flow chamber 3, so the activated source gas A is ejected from the contraction/expansion nozzle 1 as a beam stream. However, it is sufficient that the activation of the raw material gas A is performed at least before the beam flow of the raw material gas A flows into the electric field of the electric field forming means 2. On the other hand, it is also possible to activate the raw material gas A after turning it into a beam stream by irradiating it with light of various wavelengths such as ultraviolet, visible, and infrared rays, laser light, and the like.

When the beam flow of the activated source gas A enters the electric field of the electric field forming means 2, the positively charged particles are attracted to the negative electrode, while the negatively charged particles are attracted to the positive electrode, and the inside Only sexual particles move straight. Then, only these activated neutral particles react with the raw material gas B on the front surface of the base 7,
Processing such as film formation and etching will be performed on the base body 7.

In the above embodiment, the electric field forming means 2 is a pair of electrodes, but it is sufficient that the electric field forming means 2 in the present invention can selectively move the neutral particles in the activated raw material gas A in a straight line. , which generates an electron beam to form an electric field, etc. The strength of the electric field is adjusted depending on the charge of the charged particles to be formed, so that only neutral particles adhere to the substrate 7. do it like this.

[Effects of the Invention] As explained above, according to the present invention, only neutral particles can be selectively sent to the reaction field, damage caused by collisions of charged particles with large charges can be prevented, and new This is expected to be applied to reaction patterns.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of one embodiment of the present invention, and FIGS. 2(a) to (
C) is a diagram showing an example of the shape of the contraction/enlargement nozzle. 1: Reduction/expansion nozzle, 1a: Inlet, 1b: Throat, IC=outlet, 2: Electric field forming means, 3: Upstream chamber, 4: Downstream chamber, 5: Window, 6: Waveguide, 7: Base.

Claims (1)

[Claims] 1) Create an electric field in the flow path of the activated raw material gas sent as a jet stream from the contraction/expansion nozzle to selectively send neutral particles in the activated raw material gas to the reaction field. A reaction method using fine particles characterized by the following.