JPH02159376A - Method and device for light-excited cvd - Google Patents

Abstract

PURPOSE:To prevent the clouding of a light incident window and to form a uniform film at a high rate by forming a gaseous NO2 current on the substrate side in the space between the substrate and the light incident window and forming a gaseous silane compd. current thereon. CONSTITUTION:Sections 5 and 6 are formed by a perforated plate 3 and a partition plate 4 on the gas inlet side of a reaction vessel 1, and gas inlets 2a and 2b are respectively provided to the sections 5 and 6. The perforated plate 3 is made to metallic particles, ceramic particles, and heat-resistant resin, and the mean particle diameter is controlled to about 0.1mu to 1mm. Under such a constitution, the reaction vessel 1 is evacuated through an exhaust port 12, and the substrate 10 is heated to a specified temp. by a heater 11. SiH4 is then introduced from the gas inlet 2a and NO2 from the gas inlet 2b, the gas currents 13 and 14 are straightened by thew perforated plate 3, UV light irradiates from a light source 8 through the light incident window 9, and SiO2 is deposited on the substrate 10. By this method, the window 9 is not clouded, and a uniform film is formed at a high rate.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a photoexcitation CVD method and an apparatus thereof, and particularly to a photoexcitation CVD method suitable for preventing fogging of a light incident window and achieving high-speed, uniform film formation. The present invention relates to a CVD method and apparatus.

[Prior Art] The principle of the photo-excited CVD method is to promote a chemical reaction by irradiating a reaction gas with light having a wavelength corresponding to the absorption wavelength of the gas. Therefore, unlike plasma reactions, the photo-excited CVD method is not affected by charged particles and does not damage the film deposited on the substrate, so this method is considered promising for forming silicon oxide films in fields such as LSI. There is.

As shown in FIG. 4, in the conventional photoexcitation CVD apparatus, a light entrance window 33 is provided on the upper surface side of a reaction vessel 31 to allow ultraviolet light irradiated from an ultraviolet light source 32 to enter the vessel, thereby depositing a thin film. The substrate 34 used for this purpose is heated by a substrate heating heater 35 such as a halogen lamp.

Furthermore, a gas inlet 37 for introducing the reaction gas 36 into the inside of the container, and a gas exhaust port 39 for exhausting the exhaust gas 38 inside the container to the outside of the container are provided on the side surface of the reaction container 31, respectively. ing.

In this photo-excited CVD apparatus, 5iHa and Ot are introduced as reaction gases 36 from a gas inlet 37, and the chemical reaction is promoted by ultraviolet light irradiated from an ultraviolet light source 32 through a light incidence window 33, and the substrate is heated at a low temperature. S i on 34
O! is precipitated. Incidentally, examples of this type of photoexcitation CVD apparatus include those described in JP-A-61-131415 and the like.

[YA problem that the invention attempts to solve]

In the past, in conventional photo-excited CVD equipment, the substrate 34
At the same time, SiO□ is deposited on the surface of the light entrance window 33.
in, is precipitated. Since the temperature of the light entrance window 33 surface is lower than the temperature of the substrate 34 surface, 5L is deposited on the light entrance window 33 surface.
O1 has low density and absorbs and scatters ultraviolet light, which causes a decrease in the intensity of transmitted light at the light entrance window 33.

- For boat fishing, in the photo-excited CVD method, under conditions where the substrate temperature, the composition ratio of the reactant gas, and the pressure are kept constant, the deposition rate of the thin film on the substrate increases in proportion to the light irradiation intensity. It is known that Therefore, the S
i O! The precipitation not only reduces the rate of thin film formation over time, but also makes it difficult to form a film uniformly and to control the thickness of the film.

The purpose of the present invention is to solve the above-mentioned problems of the conventional technology, to prevent window fogging due to precipitates on the light entrance window, to achieve high-speed film formation, and to enable uniform film formation and film thickness control. An object of the present invention is to provide a photo-excited CVD method and apparatus.

[Means to solve the problem]

In order to achieve the above object, in the photo-excited CVD method of the present invention, multiple stages of gas flow are formed in the vertical direction in the space between the substrate and the light incidence window, and N2 is formed on the substrate side. An Ox gas flow is formed, and a silane compound gas flow is formed above it.

Furthermore, the optically excited CVD apparatus of the present invention has compartments divided into a plurality of stages in the vertical direction on the side surface side of the space between the substrate and the light incidence window, and the gas blowing surfaces of the compartments are divided into multiple stages in the vertical direction. A nozzle made of a porous body such as a sintered body of metal particles is provided, and NO□ is introduced into the lowermost compartment, and a silane compound is introduced into the upper compartment.

[Effect]

NO□ as an oxidizing gas has an absorber of 244 to 398 nm in the reaction that produces oxygen (0) in the nascent stage, and has a high absorption rate of long wavelength components such as low-pressure mercury lamps and xenon lamps, and is The reaction between NO and NO is promoted, and high-speed SiOtO film formation is achieved. Furthermore, since NO□ is a heavier gas than silane compounds such as SiH, there is less diffusion of N02 to the upper stage side, and at the same time as high-speed film formation, window clouding of the light incidence window is suppressed. Furthermore, high-speed film formation makes it easy to set uniform film formation conditions.

Next, in the photo-excited CVD apparatus of the present invention, a rectified gas flow is formed from the nozzle whose gas blowing surface is made of a perforated plate, and the effect of the above method is reliably performed.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a longitudinal cross-sectional view showing an embodiment of a photoexcitation CVD apparatus of the present invention. In FIG. 1, two gas introduction ports 2a and 2b are arranged on one side of a reaction vessel l, and the gas introduction port 2a communicates with a compartment 5 formed by a perforated plate 3 and a partition plate 4. The gas inlet 2b communicates with a compartment 7 formed by the perforated plate 3 and the partition plate 6. Further, the gas introduction ports 2a and 2b are arranged at the center of the side surface of each compartment 5.6.

The porous plate 3 is made of a porous body having fine communication holes. As this porous body, for example, one formed of a sintered body of metal particles such as stainless steel or ceramic particles, or a heat-resistant resin such as fluorine resin (for example, Teflon) is effective. The average particle diameter in the porous body is desirably 0.1 μm or more in order to prevent clogging, and 1 mm or less in order to rectify a given gas.

In addition, in FIG. 1, 8 is a light source for ultraviolet light, 9 is a light entrance window, and 1
0 is a substrate, 11 is a heater for heating the substrate, and 12 is a gas exhaust port.

In this photo-excited CVD apparatus, first, inside the reaction vessel l, ~
After being evacuated to the order of 10-'' torr, the substrate 10 is heated to a predetermined temperature by the substrate heating heater If.

Next, SiH4 or SiH4 diluted with N2 is introduced into the compartment 5 through the gas inlet 2a, and NOx diluted with Nt is introduced into the compartment 7 through the gas inlet 2b. The gas introduced into each compartment 5.7 becomes a rectified gas and is blown into the reaction vessel 1 through fine communication holes formed in the perforated plate 3.

In this case, the flow rate of gas or fluid from the nozzle is generally proportional to the 1/2 power of the pressure difference before and after the nozzle. Therefore, the pressure drop before and after the perforated plate 3 that forms the air outlet is large. Therefore, the gas pressure in the compartment 5.7 is approximately constant, and the flow rate of the gas blown out from the gas outlet formed by the perforated plate 3 is large. is uniform on the surface of the porous body, and no drift occurs.Furthermore, since there are many holes on the surface of the porous body, the flow rate of the gas blown out from those holes is extremely small.Furthermore, since the gas flow is very close to each other, there is no flow between each hole. The existing dead space becomes relatively small, and gas turbulence is less likely to cause HE. As a result, the gas blown out from the porous plate 3 is rectified without turbulence or bias.

The gas from compartment 5 thus forms a rectified upper gas stream 13 and the gas from compartment 7 forms a rectified lower gas stream 14.

In this case, the gas boundary N between gas stream 13 and gas stream 14
To prevent slippage at J15, gas flow 1
The amount of gas supplied to each compartment 5.7 is adjusted so that the linear velocities of gas flow 14 and gas flow 14 are the same.

The gas blown out from the compartment 7 through the perforated plate 3 is NOl diluted with N2, and the gas blown out from the compartment 5 through the perforated plate 3 (St114 or 5iH4 diluted with N) ), it does not mix into the upper gas flow 13 side.

Furthermore, under photo-excited CVD film formation conditions, (1) 1 to 5 to
rr, and the linear velocity of the gas flow 13.
(Heated to about 10-150"C.

Therefore, heat retention within the reaction vessel 1 is negligible.

Next, when a low-pressure mercury lamp is used as a light source, first, the region 0□→0. Ozone (0,) is generated by the reaction of 0. Next, this ozone generates nascent oxygen (O) by the reaction of 0,→0□+O in the wavelength range of 254 nm of ultraviolet light.

Finally, SiH4 as a reaction gas reacts with the oxygen in the nascent stage, and the reaction of SiH, +O→5iOz+H2 proceeds to form 310□. Therefore, from the reaction mechanism described above, the formation of Sin is not related to the photoexcitation of SiH4, but the photoexcitation in the 185 nm wavelength range of ultraviolet light from a low-pressure mercury lamp is responsible for the formation of silicon oxide (SiO7). It can be seen that the speed is the limiting factor. The absorption range of NO8 used as the oxidizing gas here is: (1) N Oz → N O+ O(228, 8
nm) (2) No, -No+○ (244
~390 nm) (3) Not ” +NOz → 2NO
As expressed by 10□-+NOs +NO (>43 6 nm), it is in a longer wavelength range than NzO as an oxidizing gas.

Here, in the reaction (2) that produces nascent oxygen (0), its absorption range is 244 to 398 nm, and this absorption range is 254 nm, which is the maximum light intensity in a low-pressure mercury lamp.
It contains nnn absorption range. As an oxidizing gas, NOt
When using, light with a wavelength of 254 m or more is sufficiently absorbed (that is, the light absorption coefficient is large), and it becomes easy to photodecompose and generate nascent oxygen (0). That is, wavelength 25
Since light of 4 nm or more is effectively used, the concentration of active species is increased.

Therefore, using NO7 as an oxidizing gas
This promotes the oxidation of 5iHn and increases the Sing film formation rate. Moreover, if the film formation rate becomes high, the film formation conditions for uniform film formation become wider, and uniform film formation becomes possible.

In addition, as shown in Fig. 3, in addition to low-pressure mercury lamps, ultra-high-pressure mercury lamps, xenon (Xe) arc lamps, and halide lamps have jJJa wavelengths of 244 to 398 nm.
In i, when silicon oxide is produced by a photo-excited CVD method with high light intensity, when an ultra-high-pressure mercury lamp, xenon, (Xe) arc lamp, or halide lamp is used as a light source, and NO□ is used as an oxidizing gas. Also,
This promotes the oxidation of SiH4 and increases the rate of film formation of Sin.

Furthermore, a low-pressure mercury lamp, an ultra-high-pressure mercury lamp, a xenon (Xe) arc lamp, and a halide lamp may be used individually, or a composite lamp may be used in which these lamps are used in combination.

In the present invention, a silane compound such as monosilane (SJ
f(,), disilane (SitH6), methylsilane (S
i'H3(CH3) ), monochlorosilane (S
i H3(C2)) etc. are used.

These silane compounds generate silicon oxide with nascent oxygen (0) generated by photoexcitation of an oxidizing gas (No.).

Incidentally, the temperature of the substrate 10 (10°C, S i Ha partial pressure 0.02 Lorr, total pressure 5 torr, molar ratio (NOz
/ S i Ha ) I , under the conditions of 11 deposition times of 10 minutes, high-speed film deposition of 60 μm/min and film pressure distribution of ±1% could be achieved. In addition, no clouding of the light incident window 9 was observed even after film formation time 1 (10 minutes). This means that no clouding of the window occurred when the film was formed with a film thickness of 6 μm, and the current It can be used for passivation in the manufacturing process of LSI and ■-■ group compound semiconductors.

FIG. 2 is a sectional view showing another embodiment of the optically excited CVD apparatus of the present invention. In FIG. 2, in addition to gas inlets 2a and 2b, a gas inlet 2c is provided on one side of the reaction vessel 1, and this gas inlet 2C is formed by a perforated plate 3 and a partition plate 2. It is connected to a compartment 22 which is divided into two compartments. Second
In the figure, the same members as those shown in FIG. 1 are designated by the same reference numerals.

In this optically excited CVD apparatus, N1 from the gas inlet 2a,
SiH4 from gas inlet 2b, NO from gas inlet 2C
8 are respectively introduced, rectified through the perforated plate 3, and 3
Forming stage gas streams 13.14.23. in this case,
The amount of gas supplied to the compartment 5.7.22 is adjusted so that no slippage of the respective gas flow occurs in the gas boundary layer 15.24.

In this embodiment, in addition to the effect of the embodiment shown in FIG. can be more reliably prevented from adhering to the surface.

In the above embodiments, Nt was shown as a gas that does not participate in photochemical reactions, but inert gases such as Ar gas and He gas can be used in addition to N2.

In addition, the gas that dilutes the silane compound or NO2 is N2
In addition to this, inert gases such as Ar gas and He gas can also be used. In this case as well, it is desirable to select gases that are heavier on the lower side of each rectifying gas.

〔Effect of the invention〕

As described above, according to the photo-excited CVD method of the present invention, it is possible to prevent the light entrance window from fogging, and to achieve high-speed and uniform film formation.
,■-V group compound semiconductor device creation process, etc.
L7 also improves the light utilization efficiency of the light source, which reduces the consumption of reaction gas, and improves high-speed and uniform film formation, allowing for high-throughput and large-area film formation operations. It becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing one embodiment of the photoexcitation CVD apparatus of the present invention, FIG. 2 is a longitudinal sectional view showing another embodiment of the photoexcitation CVD apparatus of the invention, and FIG. 3 is the emission spectrum of various light sources. FIG. 4 is a vertical cross-sectional view of a conventional photoexcitation CVD apparatus. 1...Reaction container, 2a, 2b, 2c...
・Gas inlet, 3...Perforated plate, 4,6.21・
...Division board, 5.7.22...Division room,
8... Light source for ultraviolet light, 9... Light entrance window, 10... Substrate, 11... Heater for heating the substrate, 12...・Exhaust port, 13, 14.23・
...gas flow, 15.24 ...gas boundary layer. Figure 1

Claims (10)

[Claims] (1) A substrate placed in a reaction chamber by introducing a reaction gas into the reaction chamber, introducing an oxidizing gas for the reaction gas, and utilizing a photochemical reaction caused by excitation of ultraviolet light irradiated from a light source through a light entrance window. In the case where a film is formed on the substrate side, NO_2 or NO_2 as an oxidizing gas is added to the substrate side.
A photo-excited CVD method characterized by forming a first gas flow containing _2 as a main component, and forming a silane compound or a second gas flow containing a silane compound as a main component in the upper flow. (2) A third gas flow, which is an upper flow of the second gas flow and is adjacent to the light entrance window and is made of a gas that does not participate in photochemical reactions.
2. The photoexcited CVD method according to claim 1, wherein a gas flow of . (3) The silane compound is SiH_4, Si_2H_
6. Claim (1) characterized in that it is at least one of SiH_3 (CH_3) and SiH_3 (Cl).
The photoexcited CVD method described. (4) The photo-excited CVD method according to claim 1, wherein the gas containing NO_2 as a main component consists of NO_2 and an inert gas. (5) The photoexcitation CVD method according to claim (1), wherein the gas containing the silane compound as a main component consists of a silane compound and an inert gas. (6) The photo-excited CVD method according to claim (1), wherein the third gas flow comprises an inert gas. (7) The photoexcitation CVD method according to any one of claims (4) to (6), wherein the inert gas is composed of N_2. (8) In a photo-excited CVD apparatus comprising a substrate disposed in a reaction chamber and a light entrance window disposed above the base and transmitting ultraviolet light from a light source, the substrate and the light entrance window It has compartments divided into multiple levels in the vertical direction on the side surface side of the space, each of which has a gas blowing surface equipped with a nozzle made of a porous material, and the lowest compartment contains NO_2 or NO_2 as the main component. A photo-excited CVD apparatus characterized in that a gas is introduced into the compartment, and a silane compound is introduced into a compartment above the compartment. (9) The photo-excited CVD apparatus according to claim (8), wherein the porous body is made of a sintered body of metal particles or ceramic particles, or a heat-resistant resin. (10) The nozzle has a compartment divided into three stages,
9. The photoexcited CVD apparatus according to claim 8, wherein an inert gas is introduced into the uppermost stage.