JPH01149963A - Laser cvd device - Google Patents

Abstract

PURPOSE:To improve deposition efficiency and to stabilize deposition by introducing laser light in the vicinity of a substrate to be deposited through a beam guide, and making the pressure in the beam guide higher than the pressure in a reaction chamber. CONSTITUTION:The gaseous mixture of reactants is introduced into the reaction chamber 1 provided with an exhaust port 9 from an inlet 8, and laser light is projected from a laser light inlet 2 through a synthetic-quartz window 4. The gaseous mixture is thereby activated, and the reaction product is deposited on the substrate 7. The cylindrical and convergent beam guide 10 extending from the laser light inlet 2 to the substrate 7 or to the vicinity of the substrate 7 is provided in the laser CVD device, and the laser light is led to the substrate 7 through the guide 10. A purge gas inlet 5 is further provided, and the pressure in the guide 10 is made higher than the pressure in the reaction chamber 1. As a result, a loss in the energy of the irradiation laser light is prevented, deposition efficiency is improved, and deposition can be stabilized.

Description

Detailed Description of the Invention [Summary] The present invention irradiates the inside of a reaction chamber into which a reaction mixture gas is introduced, activates the mixture gas to generate a reaction product, and generates a reaction product. Regarding laser CVD equipment for depositing onto a deposition target substrate, the purpose of the laser CVD system is to improve deposition efficiency and stabilize deposition by effectively guiding laser light to the deposition target substrate in a reaction chamber without power loss. Inside the reaction chamber, which serves as the light introduction path.

It is characterized in that a cylindrical beam guide is provided in the section from the laser beam introduction port to the section where the reaction is desired to occur.

[Industrial application field]

The present invention provides a laser CVD apparatus that irradiates a reaction chamber into which a reaction mixture gas is introduced with a laser beam, activates the reaction mixture gas, generates a reaction product, and deposits the reaction product on a substrate to be deposited. Regarding.

2. Description of the Related Art Conventionally, as an apparatus for depositing polysilicon or oxide on a semiconductor substrate or the like, there is a CVD apparatus that generates and deposits reaction products by external electrical heating.

The laser CVD apparatus according to the present invention is relatively new and is expected to find wide application in the future, including in the semiconductor field.

[Conventional technology]

FIG. 3 is a schematic cross-sectional view showing a conventional laser CVD apparatus.

In the figure, 101 is a reaction chamber, 102 is a laser beam inlet, 103 is an O ring, 104 is a synthetic quartz window, 10
5 is a purge gas inlet, 106 is a support, 107 is a substrate to be deposited, 108 is a reaction mixed gas inlet, and 109 is an exhaust port.

The illustrated laser CVD apparatus is an apparatus for depositing Sin, and after exhausting the gas in the reaction chamber 101 from the exhaust port 109 and reaching a certain pressure, the reaction mixture gas N is introduced from the reaction mixture gas inlet 108. , 0+5iJa are introduced into the reaction chamber 101. At the same time, in order to prevent the reaction mixture gas from entering the laser beam inlet 102, N2 is introduced through the purge gas inlet 105. When a laser beam is irradiated into the reaction chamber through a synthetic quartz window 104 fixed with an O-ring 103, the reaction mixture gas decomposes and reacts only in the portion irradiated with the laser beam, producing purple radical luminescence. The SiO□ thus generated is deposited on the substrate 107 to be deposited.

[Problem that the invention seeks to solve]

However, according to the conventional laser CVD apparatus described above, N2 gas is introduced into the laser beam inlet 102 inside the reaction chamber 101 through the purge gas inlet 105 to prevent the reaction mixture gas from entering the laser beam inlet 102. Despite this, it is not perfect, and the laser beam irradiation causes radical emission in this area as well, allowing the reaction mixture gas to enter.

By the way, reaction products generated by decomposition and reaction at the laser light introduction port 102 adhere to the surface of the synthetic quartz window 104 in the reaction chamber 101, reducing the transmittance of the laser light energy. Furthermore, before the laser beam reaches the substrate to be deposited 107 from the laser beam inlet 102, the reaction mixture gas existing in the laser beam path in the reaction chamber 101 decomposes and reacts, and the laser beam energy is wasted and absorbed. This also results in a decrease in energy efficiency. In the case of repeated deposition, as shown in FIG. 2, the deposition rate decreases and the thickness of the deposited reaction product does not become constant even if the same laser light energy is irradiated for the same time. Therefore, it was not possible to ensure the stability of the deposition.

Therefore, an object of the present invention is to improve deposition efficiency and stabilize deposition by effectively guiding laser light to a substrate to be deposited in a reaction chamber without energy loss.

Means for Solving Problem C] The above problem is solved by providing a cylindrical beam guide from the laser beam introduction port to the substrate to be deposited in the interior of the reaction chamber that serves as the laser beam introduction path, and This problem is solved by a laser CVD apparatus characterized by providing a purge gas inlet for pressurizing the inside of the guide to a level higher than the pressure inside the reaction chamber. Furthermore, in order to improve the effectiveness of solving the above problems, the tip of the cylindrical beam guide can be made thinner.

[Effect]

That is, in the present invention, a cylindrical beam guide is provided in a portion of the reaction chamber that serves as a laser beam introduction path from the laser beam introduction port to the substrate to be deposited, and the inside of the beam guide is filled with a purge gas into the reaction chamber. By increasing the pressure higher than the pressure of the beam guide, laser light irradiation can be performed without the reaction mixture gas entering the inside of the beam guide, so that the decomposition reaction of the reaction mixture gas and the deposition of reaction products are prevented from occurring outside the beam guide. Since the reaction products can be caused to occur in the synthetic quartz window surface, the laser light can be guided to the substrate to be deposited without causing absorption of laser light energy, improving the deposition efficiency. This makes it possible to stabilize the deposition.

[Example] Hereinafter, the present invention will be specifically explained with reference to an illustrated example.

FIG. 1 is a schematic cross-sectional view showing a laser CVD apparatus according to an embodiment of the present invention, and FIG. 2 is a comparative illustration of the effects of the laser CVD apparatus according to an embodiment of the present invention and that of a conventional example.

In FIG. 1, 1 is a reaction chamber, 2 is a laser beam introduction port, 3 is an O-ring that fixes a synthetic quartz window 4 for introducing laser light into the reaction chamber 1, and 5 is a beam guide 1.
A purge gas inlet for pressurizing the inside of the chamber, 6 a support base for supporting a substrate 7 on which a reaction product is deposited, 8 a reaction mixed gas inlet, and 9 a constant pressure in the chamber. An exhaust port, 10 is a beam guide that guides the laser beam from the laser beam inlet 2 to the substrate 7 to be deposited, and 11 is a pressure adjusting gas inlet.

The laser CVD apparatus according to the present invention shown in the same figure is particularly suitable for 5iOz
First, a substrate to be deposited is placed on a support stand 6 installed at an appropriate position in the reaction chamber 1 at a distance of about 2 cm from the tip of the beam guide 10. Thereafter, the gas in the reaction chamber 1 is exhausted from the exhaust port 9, and after reaching a constant pressure, the reaction mixture gas NtO (200 S C
CM) +S 1zH-(0.23CCM) is introduced into the reaction chamber 1 from the reaction mixture gas inlet 8. At the same time, in order to prevent the reaction mixture gas from entering the beam guide 10, N2 is introduced from the purge gas inlet 5 to make the pressure inside the beam guide 10 higher than the pressure inside the reaction chamber 1. In order to equalize the concentration of the reaction mixture gas while maintaining the relationship, N2 is introduced from the pressure adjustment gas inlet 11, and the pressure in the reaction chamber 1 is approximately 2 torr and the pressure in the beam guide 10 is approximately 6 torr.
Adjust the amount of N2 gas 1Iiii so that it becomes r. Then, when a laser beam is irradiated into the reaction chamber 1 through the synthetic quartz window 4 fixed with an O-ring 3, the reaction mixture gas emits purple radical light at f! As can be seen, decomposition and reaction occur from about 1 cm from the tip of the beam guide 10, and reaction products are deposited on the substrate 7 to be deposited.

Therefore, no reaction products adhere to the surface of the synthetic quartz window 4, and the energy of the laser beam is effectively guided to the substrate 7 without being absorbed.

FIG. 2 is a graph derived from an experiment of the relationship between the number of times of deposition and the thickness of the deposited film when the laser output is 15 W, the repetition frequency is 100 H2, and the laser irradiation time is 1 hour. A comparison is shown between a laser CVD device with a conventional beam guide and one without a conventional beam guide.

According to the conventional method, as the number of times of deposition increases, the thickness of the deposited film decreases and becomes unstable, whereas with the method of the present invention, the thickness of the deposited film is constant regardless of the number of times of deposition, and the deposition can be stabilized. Moreover, even in the first deposition, there was a difference in the film thickness, confirming the effectiveness of the beam guide installation.

[Effects of the Invention] As described above, according to the present invention, laser light can be effectively guided to the substrate to be deposited in the reaction chamber without energy loss, thereby improving the deposition efficiency and stabilizing the deposition. I can figure it out.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing a laser CVD apparatus according to an embodiment of the present invention, FIG. 2 is a diagram illustrating the effects of the laser CVD apparatus according to the present invention in comparison with that of a conventional one, and FIG. 3 is a diagram illustrating a conventional laser CVD apparatus. 1 is a schematic cross-sectional view showing a laser CVD apparatus. (Explanation of symbols) 1.101...Reaction chamber, 2.102...Laser light introduction port, 3.103...0 ring, 4,'104...Synthetic quartz window, 5.105...・Purge gas inlet, 6.106...
・Support stand, 7.107... Deposition target substrate, 8.108... Reaction mixed gas inlet, 9.109...
・Exhaust port, 10... Beam guide, 11... Gas inlet for pressure adjustment.

Claims (2)

[Claims] (1) In a laser CVD apparatus in which a laser beam is irradiated into a reaction chamber into which a reaction mixture gas is introduced, the reaction mixture gas is activated to generate a reaction product, and the reaction product is deposited on a substrate to be deposited. A cylindrical beam guide is provided from the laser beam inlet to the substrate to be deposited or in the vicinity thereof in a portion inside the reaction chamber that serves as a laser beam introduction path, and the pressure inside the beam guide is applied higher than the pressure inside the reaction chamber. A laser CVD apparatus characterized by being provided with a purge gas inlet for pressurizing the gas. (2) The laser CVD apparatus according to claim 1, wherein the cylindrical beam guide has a tapered tip.