JPH0740563B2 - Anti-fog device for light introduction window - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of application) The present invention relates to a light-introducing window fog that is optimal for preventing light-introducing windows used in a chamber of an ECR etching apparatus or the like. Regarding prevention device.

(Prior Art) Generally, an ECR (Electron Cyclotoron Resonance) etching apparatus forms ECR conditions on a wafer in a chamber,
The reaction gas is ionized by spirally moving electrons under this ECR condition, and etching is performed by irradiating the wafer surface with this ion.

In recent years, in such an ECR etching apparatus, a technique has been developed in which an excimer laser light is externally applied to the wafer surface in the chamber through a light introduction window as an auxiliary assist for activating the wafer surface.

(Problems to be Solved by the Invention) By the way, the above-mentioned light introducing window for the purpose of introducing the excimer laser light into the chamber is fogged by the volatile products generated by the etching remaining in the chamber. Sometimes. Therefore, the excimer laser light does not pass through the light introduction window, the wafer surface is not sufficiently activated, and etching may be insufficient.

The present invention has been made in view of the above circumstances, and provides a fog-preventing device for a light-introducing window capable of constantly transmitting light from a light source without causing fog on the surface of the light-introducing window. Has an aim.

[Structure of the Invention] (Means for Solving the Problems) That is, the antifogging device for the light introducing window of the present invention pulsates light to the wafer on the susceptor in the chamber through the window provided in the chamber. The light irradiating means for irradiating the wafer and the light for irradiating the wafer when the through hole is aligned with the optical path of the pulse light by rotating the plate provided inside the window and having the through hole relatively to the pulse light. An introduction optical path is formed, and an opening / closing mechanism configured to block the pulsed light at other times,
The plate is rotated in synchronization with the irradiation of light, the light introducing optical path is formed during the light irradiation period by the light irradiating means, and the light introducing window can be introduced into the reaction section, the light introducing window, and the light introducing window. A differential evacuation means is provided for supplying a purge gas between the plate and the plate, and exhausting a gas between them to perform differential evacuation.

(Operation) In the antifogging device for the light introduction window of the present invention, the introduction of light to the reaction section in the chamber is introduced in a pulsed manner so that light can be introduced into the introduction section during the light introduction period and the light is introduced during the light non-introduction period. By configuring so as to block the light introduction path, volatile products and the like are prevented from adhering to the light introduction window, and the light introduction window is not clouded. Therefore, the light from the light source can always be transmitted into the chamber.

(Example) An example in which the apparatus of the present invention is applied to an ECR etching apparatus will be described below with reference to the drawings.

A susceptor 2 is provided at a predetermined position in the chamber 1,
The wafer 3 is placed on the susceptor 2. An ion generating chamber 4 is provided above the chamber 1 at a position above the susceptor 2 so as to project with a small diameter neck. The ion generating chamber 4 is sealed from the outside by a discharge tube 5 made of quartz or alumina, and a reaction gas such as CF ₄ is introduced through an introduction hole 6. 2.45 produced by a magnetron (not shown)
The microwave of GHz is introduced into the ion generation chamber 4 through the waveguide 7, and the microwave discharge is generated in the ion generation chamber 4. Furthermore, on the outer circumference of the discharge tube 5,
A coil 8 including a solenoid coil and a permanent magnet is arranged so that a mirror magnetic field is formed in the ion generating chamber 4. Then, the electrons generated by the microwave discharge spirally accelerate due to the resonance phenomenon between the magnetic field and the microwave. As a result, ions are generated from the reaction gas and accelerated by the grid 9 to irradiate the surface of the wafer 3 for etching. An exhaust hole 10 is provided in the lower part of the chamber 1 so that the volatile products generated by the above-mentioned etching are discharged to the outside of the chamber 1.

Excimer laser light source on the surface of the wafer 3 during the above etching
A laser beam is emitted from 11 to activate the surface of the wafer 3 to assist the etching. That is, as shown in more detail in FIG. 1 and FIG.
The excimer laser light source 11 is arranged at a predetermined position outside the chamber 1 diagonally above the wafer 3 and has a light introducing tube 13 in the chamber 1.
The light is introduced into the chamber 1 through a light introduction window 14 provided in the opening of the. A lens system 15 is arranged between the excimer laser light source 11 and the light introduction window 14. With this lens system 15, the excimer laser light from the excimer laser light source 11 is focused 16 at a predetermined position in the light introducing tube 13.
Are formed. An optical switch mechanism, that is, a light shielding mechanism is provided in the light introducing tube 13 as shown in FIG. For example, the plates having the through holes are configured to be moved or rotated relative to each other. Above focus
A fixing plate 18 having a through hole 17 is attached to the position where 16 is formed. Further, on the side of the light introduction window 14 near the fixed plate 18, as shown in FIG. 4, a rotary plate 19 is rotatably arranged so that its central axis of rotation is different from the optical path of the excimer laser light. ing. A large number of through holes 20 are formed in the rotating plate 19 along the circumference of the circle at a position matching the optical path of the excimer laser light. Therefore, the rotating plate 19 is rotated and the through hole 20 and
When 17 matches, light is introduced above the wafer. Through hole 20
The laser light is shielded during the period in which the numbers 1 and 17 do not match, the reaction gas enters from the through hole 17, and the flow path is formed through the through hole 20 with the center axis deviated, so that there is a large resistance to the flow of the reaction gas. Shows sex. Particularly, since the through holes 17 and 20 are located in the peripheral portion of the light introducing tube 13, the reaction gas concentration distribution is a relatively thin region. The vicinity of the outer periphery of the rotating plate 19 is made of a conductor, and on the other hand, a large number of flat coils 21 are arranged along the outer periphery on both sides of the rotating plate 19 on the side of the light introducing tube 13 corresponding thereto. The structure of the flat motor 22 is formed by these, and the rotating plate 19 is rotated.

Further, in the light introducing tube 13 between the rotating plate 19 and the light introducing window 14, an introducing port 23 for introducing the purge gas and an exhaust port 24 for exhausting the introducing gas are provided.
And are provided for differential pumping.

Next, the control system of the excimer laser light source 11 and the flat motor 22 will be described with reference to FIG.

In the figure, reference numeral 25 is a control unit for controlling the operations of the excimer laser light source 11 and the flat motor 22, and a pulse generation unit 26
These operations are controlled based on the pulse generated from That is, as shown in FIG. 6, pulses are generated from the pulse generator 26 at a predetermined cycle T, and the controller 25 causes the flat motor 22 to rotate the rotary plate 19 based on this pulse. Further, the control unit 25 causes the excimer laser light source 11 to emit excimer laser light in synchronization with this rotation. Specifically, the turning plate 19 is turned by turning the turning plate 19.
The control is performed so that the cycle in which the through hole 20 of FIG. 3 and the through hole 17 of the fixing plate 18 coincide with the cycle in which the excimer laser light source 11 emits excimer laser light. That is, through hole 20 and through hole 17
When is coincident with, the excimer laser light from the excimer laser light source 11 is controlled so as to pass through the through holes 20 and 17 and enter the chamber. Then, the excimer laser light from the excimer laser light source 11 is applied to the surface of the wafer 3 to activate the surface of the wafer 3 and to assist the etching. Further, in the light introducing window 14 for introducing the excimer laser light into the chamber 1, as described above,
Since the one having a function such as a "shutter" composed of the rotating plate 19 and the fixed plate 18 is interposed between the inside of the chamber 1 and the inside of the chamber 1, the exhaust port 10 generated during the etching in the chamber 1 is sufficient. Volatile products remaining without being exhausted are less likely to adhere to the light introduction window 14. For this reason,
Fog hardly occurs in the light introducing window 14, and the excimer laser light from the excimer laser light source 11 can always pass through the light introducing window 14, and the function as an auxiliary assist during etching is always lost. Disappears. Further, since the differential air is exhausted between the rotary plate 19 and the light introduction window 14 by the introduction port 23 and the exhaust port 24 provided therebetween, the above-mentioned fogging prevention effect is further improved.

[Effects of the Invention] As described above, according to the fogging prevention device for a light introducing window of the present invention, the light from the light source can always be transmitted without causing fog on the surface of the light introducing window. .

[Brief description of drawings]

1 is a schematic vertical sectional front view of an ECR etching apparatus according to an embodiment of the present invention, FIG. 2 is a partially enlarged view of FIG. 1, and FIG.
FIG. 4 is a plan view showing the fixing plate in FIG. 1, and FIG.
FIG. 5 is a plan view showing the rotating plate in the figure, FIG. 5 is a block diagram showing the control system of FIG. 1, and FIG. 6 is a diagram showing pulses of FIG. 1 ... Chamber, 11 ... Excimer laser light source, 14 ... Light introduction window, 15 ... Lens system, 16 ... Focus, 17 ... Through hole, 18
...... Fixed plate, 19 ...... Rotating plate, 20 ...... Through hole.

Claims (2)

[Claims] 1. A light irradiation means for irradiating a wafer on a susceptor in the chamber with light in a pulsed manner through a window provided in the chamber, and a plate disposed inside the window and having a through hole. An opening / closing mechanism configured to be rotated relative to the pulsed light to form a light introduction optical path for irradiating the wafer when the through hole coincides with the optical path of the pulsed light, and to block the pulsed light at other times. A control unit that rotates the plate in synchronization with the irradiation of light, forms the light introduction optical path during a light irradiation period by the light irradiation unit, and allows light to be introduced into the reaction unit; and the light introduction window; A differential evacuation unit that supplies a purge gas to the plate and exhausts a gas between them to perform a differential evacuation. 2. A fog preventing device for a light introducing window according to claim 1, wherein the light source is an excimer laser light source.