JPS63213923A - Equipment for monitoring thin film - Google Patents

Abstract

PURPOSE:To enable monitoring the variation of the thickness of a thin film by providing an optical fiber for projection to project light generated from a coherence light source nonperpendicularly to the thin film and an optical fiber for receiving light to guide the reflected light from the thin film to a required position. CONSTITUTION:Windows 21, 22 fitted with quartz glass are provided face to face in the side walls of a reaction chamber 12; one end of an optical fiber 23 for projection and one end of an optical fiber 24 for receiving light are fixed each at an appropriate position. The fixing angles of the ends of both the optical fibers 23, 24 are so determined that the light propagated through the optical fiber 23 makes an angle theta with a substrate 20 and the reflected light can be received by the optical fiber 24. The other end of the optical fiber 23 is connected to a light source 25 which generates coherent light. When the light source 25 is driven, the light is propagated through the optical fiber 23 and is projected on the substrate 20. Then, an interference output variation is generated by the reflected light on the surface and the back of a film on the substrate with the variation of the thickness of the film and is propagated to an interference variation analysis equipment 26 via the optical fiber 24. Accordingly, the variation of a film thickness can be read in this equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an apparatus for monitoring film formation or etching conditions in, for example, ECR plasma Wff.

[Prior art]

ECR (Electronic Cyc) is a CVD (Chemical Vapor Deposition) device that can obtain good film quality.
Lotoron Resonance) plasma devices are known and are being put into practical use.

This device introduces microwaves into a magnetic field, feeds raw material gas into the magnetic field, generates plasma by applying electron cyclotron resonance, and guides the plasma from this plasma generation chamber to an adjacent reaction chamber. The structure is such that a film is formed on a substrate placed in a reaction chamber.

C Problems to be Solved by the Invention] By the way, although the film thickness is controlled by the film formation time, conventionally no means for actually monitoring the film thickness has been provided. Therefore, even if the required film thickness cannot be obtained for some reason, there is an inconvenience in that this is not noticed until the substrate is removed from the reaction chamber. Although the reaction chamber is equipped with a viewing window, it is only possible to confirm the generation of plasma, and it goes without saying that it cannot monitor the film thickness.

The present invention was made in order to solve such problems, and it is possible to create a thin film by projecting light using an optical fiber to cause optical interference on the front and back surfaces of the film, and guiding this interference to the outside of the plasma atmosphere using the optical fiber. It is an object of the present invention to provide a device for monitoring thickness variations.

[Means for solving problems]

The thin film monitoring device according to the present invention is attached to an ECR plasma device or a device for producing a thin film to be removed or formed, and outputs a coherent light source and light emitted from the coherent light source. a light-emitting optical fiber arranged so as to project this light non-perpendicularly to the thin film; and a light-receiving optical fiber arranged so as to receive reflected light from the thin film and guide this light to a desired position. It is characterized by comprising:

[Effect]

The coherent light is projected onto the thin film by a projection optical fiber. As the film thickness changes, this light is transmitted to the front and back surfaces of the thin film (
Interference fluctuations occur due to the light reflected by the substrate side surface).

This is captured by a light-receiving optical fiber and sent to, for example, an interference fluctuation analysis section. This makes it possible to monitor changes in the thickness of the thin film.

〔Example〕

Hereinafter, the present invention will be described in detail based on a concave surface showing an embodiment thereof. The drawings are schematic diagrams showing the overall structure of the present invention. ECR
The plasma device 1 includes a plasma generation chamber 11 and a reaction chamber 12 below the plasma generation chamber 11, and an excitation coil 13 is arranged concentrically around the plasma generation chamber 11. The plasma generation chamber 11 and a microwave source (not shown) are connected by a waveguide 14 that extends above the plasma generation chamber 11.
The microwaves propagated through the waveguide 14 enter the microwave generation chamber 11 via a quartz glass plate 15 for gas sealing.
will be introduced to

A cooling water flow chamber 16 is provided around the plasma generation chamber 11 . Further, a raw material gas supply chamber 17 is connected to the upper part of the plasma generation chamber 11 . The bottom wall of the plasma generation chamber 11 is open and serves as a plasma extraction window 18. The plasma generated in the plasma generation chamber 11 is led out to the reaction chamber 12, and a mounting table 19 is arranged below the plasma extraction window 18, on which the substrate 20 is placed.

In addition, 28 is a raw material gas supply pipe, and 31 is an exhaust port.

Now, in the apparatus of the present invention, windows 21 and 22 made of quartz glass are provided at opposite positions on the side wall of the reaction chamber 12, and one end of each of the light emitting optical fiber 23 and the light receiving optical fiber 24 is positioned. and fix it. Lenses for light focusing and imaging are attached to the terminals of both optical fibers 23 and 24 as necessary. Although the optical fiber used is not limited, the light emitting optical fiber 23 has a core diameter/cladding diameter of 100.
/150 μm pure silica optical fiber is used. The light-receiving optical fiber used is a bundle of 2,400 multi-component glass fibers each having a fiber diameter of 50 μm.

The fixed angle of this terminal is determined so that the light propagated through the light emitting optical fiber 23 makes an angle θ with the substrate 20, and the reflected light is received by the light receiving optical fiber 24.

The other end of the light projection optical fiber 23 is a light source 2 that emits coherent light.
5. As the light source 25, a semiconductor laser,
A He-Ne laser or the like may be used.

On the other hand, the other end of the light receiving optical fiber 24 is connected to the interference fluctuation analysis 1f.
It is optically coupled to fi26. The projection angle θ of the coherent light is preferably set to 7 to 20 degrees for the reasons explained later, but the feature of the ECR plasma apparatus 1 is that the substrate 20 and the plasma generation chamber 11 face each other directly, so that the projection angle θ is perpendicular to the substrate 20. It is impossible to project light from any direction, and it is essential to set it non-perpendicularly (θ≠90°).

Thus, the light spot on the substrate 20 and the light emitting optical fiber 23
The quality of the detected waveforms was examined using various values of θ when the distance X from the terminal was set to 300 to 400 fins. Table 1
shows the results, and also shows the quality of θ due to the dimensional constraints of the ECR plasma device 1.

From the above, it is preferable that θ is in the range of 7 to 20''.

The diameter of the light spot on the substrate 20 at this time was 7 to 15 mm. Next, the operation of the above device will be explained.

The microwave source is driven, the excitation coil 13 is energized, and the source gas is supplied through the tube 17.28. Then, plasma is generated in the plasma generation chamber 11, which is sent to the reaction chamber 12, and a film (not shown) of a compound determined by the supplied gas is generated on the substrate 20.

On the other hand, when the light source 25 is driven, the light propagates through the light projection optical fiber 23 and is projected onto the substrate 20. Then, as the thickness of the film thereon changes, interference output fluctuations occur due to light reflected from the front and back surfaces of the film, and this is propagated to the interference fluctuation analysis device 26 via the optical fiber 24.

Therefore, the film thickness variation can be read here.

In addition, in the above embodiment, the case where the ECR plasma device is used as a CvD device was explained, but the ECR plasma device can also be used as an etching device, and in this case, it can be used to monitor the decrease in film thickness due to corrosion. Can be used similarly.

〔effect〕

As described above, in the case of the present invention, it is possible to monitor the film thickness in an ECR plasma apparatus, which was conventionally not possible at all. Therefore, it is possible to prevent excessive or insufficient film formation or film removal, thereby improving production. The improvement in yield is remarkable.

[Brief explanation of the drawing]

The drawing is a schematic diagram of the device of the present invention. 1... ECR plasma device 11... Plasma generation chamber 12... Reaction chamber 20... Substrate 23.24...
・Optical fiber 25...Light source 26...Interference fluctuation analysis device Applicant Mitsubishi Cable Industries Co., Ltd. Agent
Patent Attorney Noboru Kono Procedural Amendment Writing Method) May 29, 1988 1, Indication of the case 1988 Patent Application No. 49740 2, Name of the invention Thin film monitoring device 3, Person making the amendment Relationship with the case Patent distributor location: 8, Higashimukojima Nishinocho, Amagasaki City, Hyogo Prefecture Name (3)
26) Mitsubishi Cable Industries Co., Ltd. Representative: Junzo Yuki 4, Agent address: 1-14 Shitennoji, Tennoji-ku, Osaka City, 543
No. 22, Nisshin Building 207, Mr. Kono Patent Office (06-779-3088)
Name (7886) Patent Attorney Noboru Kono”゛□−□
Heat 6, "Detailed Description of the Invention" and "Brief Description of Drawings" columns of the specification to be amended, Drawing 7, Contents of Amendment 7-1, "Detailed Description of the Invention" of the specification On page 4, line 4, ``The drawing is'' is corrected to ``Figure 1 is''. 7-2 In the "Brief explanation of the drawings" column of the specification, on page 8, line 2 of the specification, the phrase "the drawings are" is corrected to "FIG. 1 is". 7-3 Drawings Correct the drawings by adding figure numbers as shown in the attached drawings. (
(No change in content) 8. List of attached documents

Claims (1)

[Claims] 1. A coherent light source, which is attached to an ECR plasma device or a device for producing a thin film to be removed or formed, outputs light emitted from the coherent light source, and outputs the light emitted from the coherent light source; A light emitting optical fiber arranged to project light non-perpendicularly to the thin film, and a light receiving optical fiber arranged so as to receive reflected light from the thin film and guide this light to a desired position. A thin film monitor device comprising: