JPH05186875A - Photo-assisted cvd device - Google Patents

Abstract

PURPOSE:To provide a photo-assisted CVD device with an optical system which ensures relatively small disorder of the intensity distribution of a pencil of excited rays on a substrate to be subjected to film formation and can maintain a satisfactory state of intensity distribution on the light source side. CONSTITUTION:In this photo-CVD device, a substrate 4 to be subjected to film formation is held in a thin film formation chamber 1a, the film formation surface 4a of the substrate 4 is irradiated with a pencil R3 of excited rays emitted from an optical system P with excimer laser as a light source 11 and a gaseous material (g) led near to the surface 4a is excited with the pencil R3 of excited rays to form a thin film 6 on the surface 4a. The focal position of the optical system P is set above the film formation surface 4a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention holds a substrate to be film-formed in a thin-film forming chamber and forms an excitation light source bundle obtained by an optical system equipped with an excimer laser light source on the film forming surface of the substrate. The present invention relates to an optical CVD apparatus that irradiates along a formation surface and excites a material gas guided near the film formation surface by an excitation light beam to form a thin film on the film formation surface.

[0002]

2. Description of the Related Art The above-mentioned photo CVD apparatus has an advantage that a thin film can be formed at a relatively low temperature because a laser beam is used for forming a thin film by an excitation light beam flux. As for the film formation, a rectangular ray bundle having a side in the width direction along the film formation surface of about 200 mm and a thickness of about 2 mm was formed by a lens group provided in the optical system for film formation. Conventionally, the design of the lens group is
The main focus has been on the shape or position of the bundle of rays on the substrate (thickness along the optical axis, width, vertical separation distance, etc.).

[0003]

However, one major factor that disturbs the film formation state (condition) is the intensity distribution of laser light on the film formation surface. On the other hand, the excimer laser has its own fluctuation and
It also has a divergence angle (on the order of a few m radians).
Therefore, the light flux after being shaped by the lens group based on the design concept as described above has a considerably disturbed intensity distribution immediately above the substrate, and this factor has an effect on uniform film formation. It was Therefore, an object of the present invention is to provide an optical system on the substrate to be film-formed, in which the intensity distribution of the excitation light flux is relatively less disturbed, and a good state of the intensity distribution on the light source side can be maintained in the excitation unit above the substrate Light CV
To get the D device.

[0004]

To achieve this object, the photo-CVD apparatus according to the present invention is characterized in that the focal position of the optical system is set above the film formation surface.
The action and effect are as follows.

[0005]

In this photo CVD apparatus, since the focal position of the optical system existing in the apparatus is set above the substrate and on the optical axis thereof, the oscillation position of the excimer laser which is the light source provided in the optical system. A relatively good intensity distribution at is reproduced at this focus position. Therefore, it is possible to form a uniform thin film by exciting the material gas relatively uniformly on the substrate.

[0006]

As a result, it is possible to obtain an optical CVD apparatus capable of forming a uniform thin film on the substrate to be film-formed, in which the intensity distribution of the excitation light flux is relatively small.

[0007]

Embodiments of the present application will be described with reference to the drawings. FIG. 1 shows a schematic configuration of a CVD apparatus 1 of the present application, and FIG. 2 shows an explanatory view of a shaped state of a rectangular ray bundle to be shaped by an optical system of this apparatus.

The CVD apparatus 1 is a so-called photo CVD apparatus, and the material gas is excited and the film is formed by the thermal energy supplied by the heating body and the optical energy supplied by the laser light. Since this photo CVD apparatus can form a film at a lower temperature than a conventional simple thermal CVD apparatus, it has an advantage that a good film can be formed without causing thermal damage to a substrate or the like. The film forming surface 4 on the semiconductor (IC, LSI, etc.) substrate 4 is described below.
The case where the thin film 6 is formed on a will be described as an example. Here, the substrate 4 is a silicon substrate as an example, and the silicon oxide S which is an insulating film or a protective film is formed on the substrate 4.
A thin film 6 of iO ₂ is formed.

First, the structure of the apparatus 1 will be described.
This apparatus 1 is provided with a thin film forming chamber 1a whose internal pressure can be adjusted, and supplies a material gas g from a material gas supply passage 2 into this thin film forming chamber 1a and forms a thin film on the same. A material gas discharge path 3 for discharging from the chamber 1a is provided. Further, a substrate holding table 7 on which the substrate 4 to be a thin film is placed is provided in the central portion 1c of the thin film forming chamber 1a. The heating of the substrate 4 and the substrate holding table 7 is performed by the heater 7 a housed in the substrate holding table 7. Further, a laser light irradiation window 10 for introducing a laser light 9 for exciting the material gas g on the substrate into the thin film forming chamber 1a is provided, and an excimer laser (ArF laser) which is a laser light source for oscillating the laser light 9 is provided. ) 11 is provided on the side of the device 1. further,
A laser light exit window 12 through which the laser light 9 is guided out of the thin film forming chamber 1a is provided.

As shown in FIG. 2, a ray bundle R1 generated by the above-mentioned excimer laser 11 (ArF laser having a wavelength of 193 nm) has a width of 25 by the first optical system LS1.
It is shaped into a rectangular bundle of parallel rays R2 having a thickness of 6 mm. After this shaping, the lower side is further shaped by the second optical system LS2. The second optical system LS2 is composed of four lenses, and the first and fourth lenses LH1 and LH4 shape the width direction of the light flux,
The shaping in the thickness direction is performed by the second and third lenses LV2 and LV3. Further, the excimer laser 11,
In the optical system P including the first optical system LS1 and the second optical system LS2, the focal position of the optical system P is the film formation surface 4
It is set above a and above the central position C of the film formation surface in the direction along the optical path. By adopting such a configuration, the intensity distribution of the light flux at this portion is close to that of the light source, and the disturbance is good with little disturbance. FIG. 3 shows the positional relationship between the substrate and the focal point. The position of the substrate of the embodiment of the present application is shown by the solid line, and the position of the conventional example is shown by the chain double-dashed line. As shown as an example, the light emitted with a certain divergence angle (schematically enlarged in the figure) from a point on the optical axis forms a focus at a position above the center of the substrate.

The shape of the shaped light beam R3 on the substrate 4 will be described below. The bundle of rays R3 has widths and thicknesses of 200 mm and 3 mm at the central portion of the substrate in the optical path direction A, and is constant in the light traveling direction (70 mm in the width direction).
/ 391, 1/100) in the thickness direction. That is, by being converged in this way, the light flux R3 has a higher density on the lower side of the optical path direction A than on the upstream side, and as a result, the energy drop accompanying the excitation of the material gas g is complemented. It is possible.

The state of forming the thin film 6 on the substrate 4 using the apparatus 1 of the present application will be described below. The inside of the thin film forming chamber 1a is maintained in a temperature range of about 350 ° C. by the heater 7a, and SiH ₄ and N ₂ O as material gas g are supplied from the material gas supply passage 2. This material gas g is
It is supplied by diffusion to the central portion 1c which is the upper region of the substrate. The material gas g is supplied with thermal energy by the heater 7a at the portion 1c. On the other hand, the light energy is also supplied from the laser light 9 incident from the laser light irradiation window 10. As a result, N ₂ O is excited at the site 1 c on the substrate and dissociated, and the radicals react with SiH ₄ to cause SiO ₂ on the substrate 4.
It grows as a film. In this way, the production of the thin film 6 on the substrate 4 can be completed. At this growth stage, the laser energy is properly adjusted in the photo CVD apparatus of the present application, so that a thin film having a uniform thickness along the optical path direction can be formed more easily and surely than before. You can

[Other Embodiments] Other embodiments of the present application are listed below. (A) In the above embodiment, an example is shown in which the focal position is set above the film forming surface 4a in the direction along the optical path and above the center position C of the film forming surface. In some cases, due to factors such as the energy absorption state of the material gas, it may be possible to obtain a better film when the focus position is displaced in the optical axis direction with respect to the central position C of the film formation surface. Therefore, in order to respond to these situations,
The substrate and the focus position are configured to be relatively movable in the direction along the optical axis, and in the direction along the optical axis of the film formation surface,
A focus position adjusting means may be provided to adjust the focus position so that the focus position can be moved closer to and away from the center position of the film formation surface. In short, the focus position may be set above the film formation surface 4a.

(B) In the above embodiment, the ray bundle R
Although the width direction and the thickness direction of 3 are converged,
Even when either one is made to converge, the object of the present application can be sufficiently achieved.

(C) Further, in the above embodiment, S
Although the example of forming the SiO ₂ film on the i substrate has been described, as an example of another film, (SiH ₄
NH ₃ ), (Si ₂ H ₆ NH ₃ ) as a pair,
The configuration of the present application can also be adopted when forming the Si ₃ N ₄ film. That is, there is no limitation on the film formed.

It should be noted that reference numerals are added to the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an optical CVD apparatus of the present application.

FIG. 2 is an explanatory view of a shaped state of a rectangular ray bundle.

FIG. 3 is an explanatory diagram showing a positional relationship between a substrate position and a focus position.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Optical CVD apparatus 1a Thin film forming chamber 4 Substrate 4a Film forming surface 6 Thin film R3 Excitation light flux P Optical system g Material gas

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shigeru Morikawa Inventor Shigeru-ku, Kyoto City, Kyoto Prefecture 17 Chudo-dera Minami-cho 17 Stock company, Kansai Institute of New Technology (72) Inventor Hisashi Sakai 17 Shareoru-cho, Chudo-ku, Kyoto-shi, Kyoto Company Kansai Research Institute

Claims (4)

[Claims] 1. A substrate (4) to be film-formed is held in a thin film forming chamber (1a), and an excimer laser light source (11) is provided on a film forming surface (4a) of the substrate (4). Excitation light flux (R3) obtained by the optical system (P) is irradiated along the film forming surface (4a) to form the film forming surface (4a).
The material gas (g) guided to the vicinity is converted into the excitation light flux (R).
3) An optical CVD apparatus that is excited by 3) to form a thin film (6) on the film forming surface (4a), wherein the focal position of the optical system (P) is the film forming surface (4a).
Photo CVD apparatus set above the. 2. A lens group disposed in the optical system (P) forms a bundle of rays obtained from the excimer laser light source (11) in a cross-sectional shape perpendicular to the optical axis along the film forming surface. A side, and a first optical system (LS1) that is a rectangular bundle of rays formed by a side in a direction away from the film forming surface, and at least one of a lateral width and a thickness of the rectangular bundle of rays in the optical axis direction. , A second optical system (LS that reduces in size along the optical axis direction)
2) The photo-CVD apparatus according to claim 1, further comprising: 3. A focal position of the optical system (P) is a central position (C) of the film forming surface in a direction along the optical axis.
The photo-CVD apparatus according to claim 1, which is located above. 4. A focus position adjusting means for adjusting the focus position in a direction along the optical axis of the film forming surface (4a) so that the focus position can be adjusted to be close to or away from the central position (C) of the film forming surface. The photo-CVD apparatus according to claim 1, further comprising: