JPH04297030A - Chemical vapor deposition device - Google Patents

Abstract

PURPOSE:To raise the operation rate by providing the equipment with a heating device for heating the surface of a wall of a reaction chamber and a jetting device for jetting chemical species having an ethoxy group or methoxy group along the inner wall of the reaction chamber in the direction going away from a wafer stage. CONSTITUTION:A wafer 3 placed on a wafer stage 2 in a chamber 1 is heated to the lower limit film forming temperature or above by a heater 4. The surface of a wall of the chamber 1 is heated to the temperature of gas nearby or above by a heater 10. When reaction gas B and O2 gas C are jetted from a gas head 6 toward the surface of the wafer 3 while the exhaust is conducted through an exhaust port 5, an SiO2 film A is formed on the surface of the wafer 3 and a reaction product is eliminated from the equipment. In addition, TEOS steam 16 is blown out through a steam blowout port 15 along the inner wall of the chamber 1 for preventing a reaction product film from being generated on the inner face of the chamber 1 or near the surface of a wall of an exhaust path. Consequently, the unnecessary reaction product film or reaction product is prevented from being formed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical vapor deposition apparatus, and more particularly to a chemical vapor deposition apparatus used in a film forming process for semiconductor devices.

0002

2. Description of the Related Art FIG. 3 is a cross-sectional side view of a conventional chemical vapor deposition apparatus of the so-called post-mix type. The wafer (3) placed on the wafer stage (2) in the chamber (1) is heated by the heater (4) in the wafer stage (2).
) is heated by Then, while exhausting from the exhaust port (5), the reaction gas (B) and O2 gas (C) are injected from the gas head (6) onto the surface of the wafer (3). A reaction product film (
A) is formed.

0003

[Problems to be Solved by the Invention] However, in this type of conventional chemical vapor deposition apparatus, a reaction product film ( In addition to A), wafer stage (2)
A reaction product film (F) generated by a thermochemical reaction adheres to a high temperature area around the lower limit temperature for film formation (see FIG. 3). In addition, in the low temperature part below the lower limit temperature for film formation [the part away from the ceiling of the chamber (1) and the wafer stage (2)], there is a The reaction product (G) is attached (see Figure 3). When the amount of these reaction product films (F) and reaction products (G) increases, they peel off from the place where they are attached, and they are attached to the wafer (
3) Attach to. If this happens, the yield of the product will decrease, so it is necessary to periodically stop the equipment and remove the attached reaction product film (F) and reaction product (G), which reduces the operating rate of the equipment. There was a problem in that it caused a decline.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a chemical vapor deposition apparatus in which unnecessary reaction product films and reaction products are not generated in the chamber.

[0005]

[Means for Solving the Problems] A chemical vapor deposition apparatus according to the present invention heats a wafer placed on a wafer stage surface in a reaction chamber and supplies a reaction gas to the wafer surface. In a chemical vapor deposition apparatus for forming a film, a heating means for heating a wall surface of the reaction chamber, and a chemical species having an ethoxy group or a methoxy group are ejected along an inner wall of the reaction chamber in a direction away from the wafer stage. The invention is characterized by comprising an injection means.

[0006]

[Operation] In the present invention, the wall surface of the chamber is heated to a temperature higher than the lower limit temperature for film formation using a heating means that heats the wall surface of the chamber, and ethoxy groups or methoxy groups are added along the inner wall of the reaction chamber in a direction away from the wafer stage. By providing an injection means for injecting vapor of the chemical species and increasing the flow rate of the vapor from the injection means, it is possible to prevent the formation of unnecessary reaction product films and reaction products.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a cross-sectional side view showing an embodiment of a chemical vapor deposition apparatus according to the present invention. This device is of the so-called post-mix type. Chamber (1)
The wafer (
3) is heated to a temperature higher than the lower limit temperature for film formation by a heater (4) in the wafer stage (2). In addition, the heater (
10) heats the wall surface of the chamber (1) to a temperature higher than the temperature of the nearby gas. While exhausting from the exhaust port (5), a reactive gas (B) is supplied from the gas head (6) to the surface of the wafer (3).
) (for example, SiH4) and O2 gas (C), a reaction occurs on the wafer (3), producing a SiO2 film (A) and a reaction product (G). The reaction product (G) diffuses to the surrounding area, but at this time, the wall surface of the chamber (1) and the inner wall of the exhaust passage around the wafer stage (2) and gas head (6) are heated as described above. Therefore, the reaction product (G) is prevented from being deposited on the wall surface due to thermophoresis caused by the temperature difference with the flowing gas, and is discharged from the apparatus.

However, if this continues, a reaction product film (F) may be generated due to a thermochemical reaction and adhere to the inner wall of the chamber (1). Therefore, steam [for example, tetraethoxysilane (TEOS)] (16) is blown out along the inner wall of the chamber (1) from the steam outlet (15), and the steam (16) is blown out along the inner wall of the chamber (1).
1) By creating an atmosphere with excess TEOS vapor on the inner surface and near the wall surface of the exhaust passage, it is possible to prevent the reaction product film (F) from forming.

As mentioned above, the vicinity of the exhaust passage wall is exposed to TEOS.
The fact that the reaction product film (F) is not generated by creating an atmosphere with excess steam will be explained using the graph of FIG. 2. Figure 2 shows TEOS and S under the condition of SiH4/O2 flow rate ratio 1/10.
It is a graph showing the relationship between the flow rate ratio of iH4 and the film formation growth rate. As can be seen from this graph, when the flow rate of TEOS vapor becomes about 0.5 times the flow rate of SiH4 gas, the film growth rate begins to decrease rapidly, and when the flow rate of TEOS vapor becomes about twice the flow rate of SiH4 gas, If it exceeds this, film formation will not be performed. This is because the ethoxy group in TEOS becomes ethanol and inactivates the O atom that accelerates the chain reaction between SiH4 and O2.

[0010] The effect of inactivation of the reaction by TEOS is as follows:
The smaller the SiH4/O2 flow rate ratio is, the larger it is. Therefore, in the TEOS vapor excess atmosphere around the wafer stage and in the exhaust passage where SiH4 is reduced due to the reaction and the SiH4/O2 flow rate ratio is small, the reaction product film (F) is not produced, and the reaction product film (F) is This prevents the particles from adhering to the inner wall surface of the chamber (1). As a result, there is no need to stop the apparatus and clean the inner wall surface of the chamber (1) as in the past, and the operating rate of the apparatus does not decrease.

In the above embodiment, a case has been described in which the wall surface of the chamber (1) is heated using the heater (10) as a heating means, but other heating means may be used. Further, the position, shape, and number of the steam outlet (15) are not limited as long as the steam (TEOS steam in this example) can be blown out in the direction away from the wafer stage (2) along the inner wall of the chamber (1). . Furthermore, although TEOS steam was used in this example as the steam (16) sprayed onto the inner wall surface of the chamber (1), the steam was
An inert gas such as 2 gas may be added as a carrier.

[0012] In the above embodiment, a post-mix type device was explained, but the reaction gas (B) and O2
The present invention can also be applied to a so-called premix type in which the gas (C) is mixed in advance and sprayed onto the surface of the wafer (3).

Further, in the above embodiment, the reaction gas (B) is SiH4 gas, but it may be SiH4 gas containing several percent of PH3 (phosphine) or B2H6 (diborane).

[0014] Furthermore, although the explanation has been made using TEOS vapor as the gas to be blown out, any gas having a methoxy group or an ethoxy group has the effect of deactivating O atoms,
It can be expected to have the same reaction suppressing effect as S vapor.

As described above, according to the present invention, there is provided a heating means for heating the wall surface of the reaction chamber, and a chemical species having an ethoxy group or a methoxy group is injected along the inner wall of the reaction chamber in a direction away from the wafer stage. Since the injection means is provided, by heating the wall surface of the reaction chamber to a temperature higher than the lower limit temperature for film formation and increasing the flow rate of the vapor, unnecessary reaction product films and reaction products can be prevented from adhering to the wall surface of the reaction chamber. do not have. As a result, it is no longer necessary to periodically stop the apparatus to clean the inner wall surface of the chamber, which has the effect of improving the operating rate of the apparatus.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional side view showing an embodiment of a chemical vapor deposition apparatus according to the present invention.

FIG. 2 is a graph for explaining the operation of the device shown in FIG. 1;

FIG. 3 is a cross-sectional side view showing a conventional chemical vapor deposition apparatus.

[Explanation of symbols] 1 Chamber 2 Wafer stage 4 Heater 6 Gas head 10 Heater 15 Steam outlet 16 Steam (TEOS) B Reactant gas C O2 gas Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A chemical vapor deposition apparatus that forms a desired film by supplying a reaction gas to the wafer surface while heating a wafer placed on a wafer stage surface in the reaction chamber. Chemical vapor phase growth characterized by comprising a heating means for heating a wall surface and an injection means for ejecting a chemical species having an ethoxy group or a methoxy group in a direction away from the wafer stage along the inner wall of the reaction chamber. Device.