KR20000019379A - Cvd(chemical vapor deposition) device - Google Patents

Abstract

PURPOSE: A CVD(chemical vapor deposition) device improves a structure of process tube, and enhances a process uniformity. CONSTITUTION: In a CVD(chemical vapor deposition) device, an inner tube(14) forms a flange to another end to which a reaction gas is discharged. Therefore, a space discharging the reaction gas becomes narrow because of the flange, a density of reaction gas of the another end of the inner tube is maintained at a high level. As a result, a stable thin film deposition is made, thereby enhancing a uniformity.

Description

Chemical Vapor Deposition (A CHEMICAL VAPOR DEPOSITION)

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chemical vapor deposition apparatus used in a semiconductor manufacturing process, and more particularly, to improve the uniformity of a process by improving the structure of a process tube.

Among the equipments used in the manufacturing process of semiconductor devices, a chemical vapor deposition (CVD) apparatus is used to deposit thin films.

The concept of the CVD process sends gaseous chemicals, including material atoms, to be deposited into the process chamber, where the chemicals react with other gases to form the desired material and deposit the material onto the wafer. In such CVD equipment, the deposition of a thin film under a pressure of 0.1 to 100 Torr is a low pressure (LP) CVD method.

In the above-described thin film deposition apparatus, the process chamber of the chemical vapor deposition apparatus having a vertical structure generally has a double tube structure. The temperature of the chamber for the process conditions is controlled by a heater installed outside the tube.

1 is a view showing the overall configuration of a conventional LPCVD used for the above-described application. Referring to FIG. 1, the process chamber has a dual structure of an outer tube 102 and an inner tube 104. Within the inner tube 104 is a boat 120 in which a plurality of wafers 122 are stacked. In addition, an injector nozzle 106 for supplying a reaction gas is provided at a lower end of the process chamber.

In the LPCVD apparatus having the above-described structure, the tube is heated by the heater 108, and the necessary materials are deposited on the wafers according to process conditions such as the pressure inside and the flow rate of the reaction gas. In the prior art, different temperature gradients in parts of the tubes were used to optimize the process. However, this results in different heat budgets between the wafers in process in the same batch, which adversely affects the uniformity of the process. On the other hand, the reaction gas is injected and supplied from the inject nozzle 106. Since the inject nozzle is fixed at one point, the concentration distribution of the reaction gas varies depending on the parts (upper, middle, lower) in the inner tube 104. In particular, dilution and exhaustion of the reaction gas occurs in the outlet portion of the inner tube 104 through which the reaction gas is withdrawn.

In this way, when the dilution and concentration distribution of the reaction gas in the inner tube 104 is not constant, a plurality of wafers are stacked on the boat 120 in the chamber and the wafers are stacked at the same time. This results in a difference in thickness and uniformity of the thin film formed according to the following.

The present invention is to solve such a conventional problem, the purpose of the new type of chemical vapor deposition to minimize the dilution and exhaustion of the reaction gas generated in the discharge portion of the inner tube through which the reaction gas escapes To provide a device.

1 is a view showing the overall configuration of a conventional chemical vapor deposition apparatus;

2 shows an inner tube installed in a process chamber of an LPCVD apparatus according to an embodiment of the present invention;

FIG. 3 is a schematic view of the LPCVD apparatus of the present invention in which the inner tube shown in FIG. 2 is installed.

Explanation of symbols on the main parts of the drawings

12: outer tube 14: inner tube

14a: outlet 14b: inlet

16 flange 18 inject nozzle

20: heater 30: vertical boat

32: wafer

According to a feature of the present invention for achieving the above object, the chemical vapor deposition apparatus is installed in a vertical outer tube, the process chamber having a cylindrical inner tube in which the reaction gas is introduced from one end, the reaction gas is drawn out to the other end In the chemical vapor deposition apparatus having: the inner tube is formed inside the flange at the other end through which the reaction gas escapes, the space through which the reaction gas escapes narrowed by the flange so as to react at the other end of the inner tube It is characterized in that the gas concentration can be maintained high.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to FIGS. 2 to 3. In addition, in the drawings, the same reference numerals are denoted together for components that perform the same function.

In general, the process conditions affecting the uniformity of the process performed in the chemical vapor deposition apparatus include the distribution of temperature in the process chamber and the supply of pressure and reactant gas. The present invention aims to improve the uniformity and reproducibility of thin films deposited on wafers by improving the flow (distribution) of the reaction gas supplied to the inner tube of the process chamber.

2 is a view showing an inner tube installed in a process chamber of an LPCVD apparatus according to an embodiment of the present invention.

2, the inner tube 14 is cylindrical in shape. Inside the inner tube 14, a vertical boat 30 in which a plurality of wafers 32 are stacked is positioned. (See FIG. 3) The inner tube 14 has an inlet portion 14b through which a reaction gas is introduced. And a discharge portion 14a through which the introduced reaction gas is discharged. On the other hand, the discharge portion 14a is formed with a flange 16 inward. That is, since the discharge portion 14a is formed smaller than the diameter of the inlet portion 14b into which the reaction gas flows, the reactive gas provided to the inner tube 14 reaches a portion (discharge portion portion) where the diameter becomes smaller. The density is increased. Therefore, it is possible to prevent dilution and exhaustion of the reaction gas, which has occurred in the discharge portion of the conventional inner tube. The inner tube is installed in an outer tube of the process chamber.

3 schematically shows an LPCVD apparatus of the present invention having an inner tube having the above-described structure, and the process of the apparatus will be described as follows.

First, the wafers loaded on the wafer carrier are transferred to the vertical boat 30 so as to be loaded into the process chamber 10 before the process proceeds. When the stacking of the plurality of wafers 32 on the vertical boat 30 is completed, the vertical boat 30 is loaded into the inner tube 14 of the process chamber 10 by the loading equipment. The vacuum pump (not shown) and the heater 20 are operated to maintain the pressure and temperature of the process chamber 10 at an appropriate level. When the pressure and temperature in the process chamber 10 satisfy the process conditions, a reaction gas is supplied through the inject nozzle 18 to deposit a desired film on the surfaces of the wafers.

Meanwhile, the reaction gas flowing into the inner tube 14 reacts with the wafers 32 located in the inner tube 14. And the reaction gas is moved to the discharge portion (14a) of the inner tube 14 and exits through the discharge portion. Gases exiting the inner tube are exhausted through the exhaust line 40. At this time, the reaction gas provided into the inner tube 14 is stagnated at the discharge portion 14a whose diameter is relatively small compared to the inlet portion 14b. Therefore, the phenomenon in which the reaction gas is diluted from the conventional inner tube 14 toward the discharge portion 14a portion can be minimized, and the concentration of the reaction gas at the discharge portion 14a portion can be increased.

As described above, the LPCVD apparatus of the present invention increases the stagnation time of the reaction gas in the discharge portion 14a of the inner tube 14, thereby sufficiently activating it, thereby providing a uniform gas distribution throughout the inner tube.

According to the LPCVD apparatus of the present invention, by minimizing the dilution of the reaction gas from the inner tube to the discharge portion, by maintaining a constant concentration distribution of the gas in the inner tube, deposition of a stable thin film The uniformity can be improved.

Claims (1)

A chemical vapor deposition apparatus having a process chamber having a cylindrical inner tube installed inside a vertical outer tube and having a reaction gas introduced from one end and exiting the reaction gas at the other end: The inner tube forms a flange inwardly at the other end through which the reaction gas escapes, such that the space through which the reaction gas escapes is narrowed by the flange so that the reaction gas concentration at the other end of the inner tube can be maintained high. Chemical vapor deposition apparatus characterized in that.