JPS62290873A - Laser cvd apparatus - Google Patents

Abstract

PURPOSE:To form a thin film of high reliability on a substrate kept at room temp. by ionizing a film forming gas with laser light having a short wavelength and by drifting the resulting ions toward the substrate with an electric field. CONSTITUTION:A film forming gas fed into a reaction chamber 5 is photodissociated with ultraviolet laser light 2 and ionized with laser light 9 having a short wavelength and high photon energy. Voltage is then applied to an electrode 10 for forming an electric field to drift the resulting ions toward a substrate 6. The migration of a reaction product deposited on the surface of the substrate 6 can be accelerated by regulating the voltage applied to the electrode 10, so the adhesion of a thin film is improved and a dense thin film can be formed.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention [Industrial Application] This invention relates to a laser CVD device, for example, the ultimate development of high-density integrated circuits, semiconductor films, metal panels, and magnetic coils. The present invention relates to an apparatus for forming a superconducting thin film etc. on a substrate with good adhesion and density while maintaining the average temperature of the substrate at approximately room temperature.

[Conventional technology]

In order to realize high-density integrated circuits, it is strongly desired to reduce the temperature of the thin film formation process in order to avoid adverse effects of heat on the elements. Furthermore, when forming a superconducting thin film of NbN, NbGe, or the like, attempts are being made to synthesize thin films at low temperatures because of the need to freeze the high-temperature phase.

As a new technology to meet this demand, a so-called laser CVD technology has been proposed, which uses the high photon energy of ultraviolet laser light to photodissociate a film-forming gas to form a thin film. This technology has the excellent feature of being able to dissociate gases using only high photon energy, allowing the reaction products to be deposited on a certain plate at low temperatures; however, because the interaction between the substrate and the reaction products is poor, Adhesion to the reaction product could not be obtained.

Figure 2 shows an example of Maruba's paper (1 <, 5 olanki et a
l, (7) Applied Physics Lett
43, No. 5, pp. 454-456).

In the figure, (1) is an ultraviolet laser oscillator, (2) is an ultraviolet laser beam, and C3) is an energy record that uses the ultraviolet laser beam (2) emitted from the ultraviolet laser oscillator (1) to dissociate the film-forming gas. A cylindrical telescope (4) is used for shaping the film-forming gas atmosphere and the atmosphere, and a window (I!) is used to introduce ultraviolet laser light into the reaction chamber (5) while blocking the film-forming gas atmosphere from the atmosphere. N+) is a supply port for film-forming gas, 6 is its discharge port, (5) is a substrate, and (7) is a susceptor with a heater for heating the substrate (6).

Ultraviolet laser light (
2) is adjusted to an energy density appropriate for dissociation of the film-forming gas by a cylindrical telescope (3), and introduced into a reaction chamber (5) through a window (4) to form a film-forming gas atmosphere. The ultraviolet laser beam (2) passes over the substrate (6) placed in the reaction chamber (5) in parallel to the substrate (6) to dissociate the film-forming gas. The reaction product obtained by this dissociation reaction is deposited on the substrate (6) by diffusion. However, as mentioned above, since the reaction product does not possess strong kinetic energy, it has poor interaction with the substrate (6), making it impossible to obtain a film with good adhesion. Therefore, in the conventional apparatus shown in Fig. 2, the substrate 46j is heated to several 100'C by the heater-equipped susceptor (7) in anticipation of the migration effect of the reaction products on the surface of the substrate (6). I was taking 1″ history.

[Problem that the invention seeks to solve]

Conventional laser CVD equipment was configured as described above, so in order to obtain a film with good adhesion, it was necessary to heat the entire substrate (6) with a heater, which required heating at room temperature required in semiconductor manufacturing processes, etc. There was a problem in that it was not possible to obtain a highly reliable film under the conditions.

This invention was made to solve the above-mentioned problems, and aims to provide a laser CVD apparatus that can obtain a reliable thin film while maintaining the average temperature of the substrate at room temperature. The purpose is

[Means for solving problems]

The laser CVD apparatus according to the present invention includes a reaction chamber that forms a film-forming gas atmosphere and a substrate is installed therein, an ultraviolet laser beam that is irradiated into the reaction chamber and dissociates the film-forming gas, and an ultraviolet laser beam that is applied to the substrate. A short wavelength laser beam that is irradiated in parallel and ionizes a part of the film-forming gas dissociated by the ultraviolet laser light, and an electric field forming electrode that moves the ionized film-forming gas onto the substrate. It is something.

[Operation] In this invention, a part of the film-forming gas or dissociated gas is ionized with a short wavelength laser beam having photon energy, and this is moved toward the substrate in the zi field, thereby increasing the average temperature of the substrate. The kinetic energy fl of an ion when maintained at room temperature! It is used to promote the migration effect of the reaction product and obtain a highly reliable thin film that has good adhesion and is dense.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings, focusing on the formation of a silicon nitride thin film for a protective film of VLSI. 1st
The figure is a cross-sectional configuration diagram showing a laser CVD apparatus according to an embodiment of the present invention. In the figure, (1) is an ultraviolet laser oscillator, (2) is an ultraviolet laser beam, (3) is a cylindrical telescope, (4) is a window, (5) is a reaction chamber, and (6) is a silicon substrate after aluminum wiring. , (7) is a susceptor that holds the substrate (6), (8) is a short wavelength laser oscillator, (9) is a short wavelength laser beam, and αq is an electric field forming electrode that forms an electric field perpendicular to the substrate (6). be. It is supplied from the film-forming gas supply port (51).

Disilane (5i2H6) door in the reaction chamber (5): / Monia (NH3) film forming gas (several Torr
~ number + Torr) is the cylindrical telescope (3
) is efficiently photodissociated by ultraviolet laser light (2) such as ArF excimer laser light shaped to have an appropriate energy density. Wavelength of ArF excimer laser light: 193-
corresponds to the peak wavelength of the absorption band of ammonia, and is also the wavelength at which absorption occurs in disilane as well. Since the energy of dissociation of this film-forming gas is lower than the energy of absorbed photons, photodissociation can easily occur. A laser beam with high photon energy is emitted from a short pulse laser oscillator (8), shaped by a cylindrical telescope (3) to a laser power density of approximately several + MW/ffl, and irradiated parallel to the substrate (6). A short wavelength laser beam (9) such as F2 excimer laser beam has the ability to partially ionize the film-forming gas or the dissociated gas. For example, the ionization energy of ammonia is said to be about 10.5 ev, while the photon energy of F2 excimer laser is 7.5 ev.
! 1 eV. By increasing the power density of the F2 excimer laser beam and realizing two-photon absorption, it becomes possible to form ions locally and spatially. For this ionization, the higher the energy of the photon of the laser light is, the more convenient it is. By applying a voltage to the electric field forming electrode C1O, the formed ions are caused to drift in the direction of the substrate (6). When the applied voltage is adjusted so that the ions have a kinetic energy of several EV or less, the ions are caused to drift on the substrate surface. The migration effect of the deposited reaction products can be promoted, the adhesion of the thin film to the substrate can be improved, and a dense thin film can be obtained.

Damage to the substrate caused by ions can be minimized by adjusting the number of ions by adjusting the power density of the short wavelength laser beam, and adjusting the kinetic energy of the ions by adjusting the voltage applied to the electrodes.

In this way, in the above embodiment, the kinetic energy of the ions can be used to promote the migration effect of the reaction products while maintaining the average temperature of the substrate (6) at room temperature, which is necessary to prevent thermal effects. , it is possible to form a dense thin film with high adhesion at low temperatures. Note that in the above embodiment, the ultraviolet laser beam (2) is irradiated parallel to the substrate (6), but if the direction is such that the film forming gas on the substrate (6) can be dissociated, this can be used. It is not limited to.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a reaction chamber that forms a film-forming gas atmosphere and in which a substrate is placed, an ultraviolet laser beam that is irradiated into the reaction chamber and dissociates the film-forming gas, and A short wavelength laser beam that is irradiated parallel to the substrate and partially ionizes the film-forming gas dissociated by the ultraviolet laser light, and an electric field forming electrode that moves the ionized film-forming gas onto the substrate. Since the laser CVD apparatus is configured, a highly reliable thin film can be formed without causing thermal damage to the substrate while maintaining the average wet layer of the substrate at room temperature.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional configuration diagram showing a laser CVD apparatus according to an embodiment of the present invention, and FIG. 2 is a cross-sectional configuration diagram showing a conventional laser CVD apparatus. In the figure, (2) is an ultraviolet laser beam, (5) is a reaction chamber, 6]) is a film-forming gas supply port, A6) is a silicon substrate, (9) is a short wavelength laser beam, and 00 is for electric field formation. It is an electrode. In the figures, the same reference numerals indicate corresponding parts.

Claims (4)

[Claims] (1) A reaction chamber that forms a film-forming gas atmosphere and in which a substrate is installed; an ultraviolet laser beam that is irradiated into the reaction chamber and dissociates the film-forming gas; A laser CVD apparatus comprising: a short wavelength laser beam that ionizes a portion of the film-forming gas dissociated by the ultraviolet laser light; and an electric field forming electrode that moves the ionized film-forming gas onto the substrate. (2) The laser CVD apparatus according to claim 1, wherein the ultraviolet laser beam is irradiated parallel to the substrate. (3) The laser CVD apparatus according to claim 1, wherein the electric field forming electrode forms an electric field perpendicular to the substrate. (4) The substrate is maintained at room temperature.
3. A laser CVD apparatus according to any one of Items 3 to 3.