JPH01270233A - Cvd equipment for semiconductor device manufacture - Google Patents

Abstract

PURPOSE:To prevent strain and contamination of a wafer, by installing a preliminary heating tube to heat the wafer at a temperature equal to or less than the vapor growth temperature before the wafer is carried in a reaction tube, and linking the tube with the reaction tube so as to be continuous. CONSTITUTION:Wafer 7 for semiconductor is heated at a temperature equal to or less than the vapor growth temperature by a preliminary heating tube 4 linked with a reaction tube 3, before the wafer is carried in the reaction tube 3. The wafer 7 is heated at vapor growth temperature by the reaction tube 3, and a CVD film is formed on the wafer 7, by applying reaction gas under a reduced pressure atmosphere. A gate valve 2 is interposed between the preliminary heating tube 4 and the reaction tube 3, and opens and closes the tube channel in an air-tight state. By performing the inverse operation, the wafer 7 is taken out from the reaction tube 3 to the inside of the preliminary heating tube 4. The temperature of the preliminary heating tube 4 is kept at a constant value equal to or less than the vapor growth temperature, or the temperature is gradually decreased to approach the temperature of the open air. Thereby, strain and contamination of the wafer can be prevented.

Description

[Detailed Description of the Invention] [Summary] Regarding CVD equipment used for manufacturing semiconductor devices, the purpose of maintaining the wafer in a good condition during CVD film formation is to process semiconductor wafers in a vapor phase. Along with heating to growth temperature,
a reaction tube for forming a CVD film on the wafer by adding a reaction gas under a reduced pressure atmosphere; and a preheating tube that communicates with the reaction tube and heats the wafer at a temperature below the vapor phase growth temperature before transferring the wafer to the reaction tube. and a gate valve 7 interposed between the preheating tube and the reaction tube to open and close the pipeline in an airtight manner.

[Industrial application field]

The present invention relates to a CVD method used when manufacturing semiconductor devices.
The present invention relates to an apparatus, and more particularly to a tube furnace type CVD apparatus.

[Conventional technology]

When forming a film such as Sing or PSG on a wafer of a semiconductor device, a tubular furnace type CVD equipment ff40 as shown in FIG. 3(a) is used.

In this CVD apparatus, a plurality of wafers 42 attached to a basket 41 are placed in a tubular reaction tube 43, a reaction gas is added thereto to reduce the pressure, and the reaction tube 43 is heated to a vapor phase growth temperature by a heater 44. The wafer 42 is formed by vapor phase growth.
Various films are formed on top of it.

[Problems to be Solved by the Invention] However, in this type of apparatus, the wafers 42 are loaded and unloaded using the fork 45 while the reaction tube 43 is maintained at the vapor phase growth temperature. When unloading, as shown in FIGS. 3(b) and 3(c), the wafer 42 may be distorted due to the temperature difference between the wafer 43, the reaction tube 43, and the outside air, and the reaction tube may be distorted due to the temperature difference. There is a problem in that air convection occurs in the opening 46 of the reaction tube 43, and the CVD film 47 attached to the inner wall of the reaction tube 41 is partially peeled off, contaminating the wafer 42 and reducing the yield of device fabrication.

The present invention has been made in view of these problems, and an object of the present invention is to provide a CVD apparatus for semiconductor devices that can maintain a wafer in a good condition during CVD film formation.

(Means for solving the ff! problem) The problem described above is to heat the semiconductor wafer 7 to a vapor phase growth temperature and to form a CVD film on the wafer 7 by adding a reaction gas under a reduced pressure atmosphere. a reaction tube 3; a preheating tube 4 communicating with the reaction tube 3 and heating the wafer 7 below the vapor phase growth temperature before transferring it to the reaction tube 3; and the preheating tube 4 and the reaction tube 3. This is achieved by a CVD apparatus for semiconductor devices characterized by having a gate pulp 2 interposed between the gate pulp 2 and the gate pulp 2 to open and close the conduit in an airtight state.

[For production]

With the gate valve 2 closed, the reaction tube 3 is heated to maintain the vapor phase growth temperature, while the preheating tube 4 is heated to below the vapor growth temperature, and the wafer is placed in the preheating tube 4. 7 and then heat the wafer 7 at a temperature that does not cause distortion.
Preheat.

Next, the gate valve 2 is opened to transport the wafer 7 into the reaction tube 3, and then the gate pulp 2 is closed.

In this state, the temperature difference between the reaction tube 3, the preheating tube 4, and the wafer 7 is small, so not only is there no distortion in the wafer 7, but also almost no air convection occurs within the reaction tube 3, and the reaction tube 3. The CVD film attached to the inner wall does not peel off.

In this reaction tube 3, the wafer 7 is heated and the temperature gradually rises from the preheated state until the temperature reaches the vapor phase growth temperature.

Here, when the air in the reaction tube 3 is treated to reduce the pressure and a reaction gas is supplied to the reaction tube 3, the wafer 7 is
CVD film depending on the nature of the reaction gas, e.g. s r O!
B2, psc film, etc. are grown in a vapor phase.

Furthermore, after forming CVDIIa on the wafer 7, the inside of the reaction tube 3 is brought to normal pressure, and the gate valve 2 is opened in this state. Almost no gas convection occurs within the reaction tube 3, so that the C V D H formed on the inner wall of the reaction tube 3 does not peel off, and dust from the CVD film rarely adheres to the wafer 7.

Next, the semiconductor wafer 7 is taken out from the reaction tube 3 into the preheating tube 4 by performing the operation opposite to the above, and the temperature of the preheating tube 4 is maintained at a constant temperature below the vapor phase growth temperature, or
Or gradually reduce the temperature to bring it closer to the temperature of the outside air.

This makes it difficult for the wafer 7 to be distorted when the wafer 7 is taken out from the preheating tube 4 .

〔Example〕

FIG. 1.2 shows an embodiment of the present invention,
The symbol l in the figure is a tube and cane furnace type CVD equipment, and this CVD equipment w
, l are a cylindrical reaction tube 3 and a preheating tube 4 that communicate with each other while maintaining an airtight state through an electromagnetic opening/closing gate pulp 2.
The reaction tube 3 and preheating tube 4 are surrounded by a reaction tube heater 5 and a preheating tube heater 6, respectively.

The reaction tube 3 described above is heated to a vapor phase growth temperature 12 (for example, 800° C.) by a reaction tube heater 5, and is a CVD film forming chamber in which a film of Sing, PSG, etc. is formed on the surface of a wafer 7 carried into the reaction tube 3. A wafer transfer port 20 for loading and unloading the wafer 7 is provided at the rear end, and an exhaust port 8 connected to an exhaust pump (not shown) is provided at the tip. At the rear of 9,
A reaction gas supply port 10 is formed to supply the reaction gas, and the reaction gas is supplied to the reaction gas supply port I in a reduced pressure atmosphere.
It is configured to flow from O toward the exhaust port 8.

On the other hand, the preheating tube 4 is adjustably heated by a preheating tube heater 6 to a temperature lower than the vapor phase growth temperature, and the wafer 7 is heated to a temperature that does not cause distortion before being carried into the reaction tube 3. (for example, 600°C), an exhaust port 12 is provided in front of the peripheral wall 11, and an inert gas supply port 13 is formed in the rear of the peripheral wall 11 to prevent the formation of CvDll'3. As a pre-process, the wafer 7 is heated by supplying nitrogen gas (N2) to the preheating tube 3 under a normal pressure atmosphere.

14, the plurality of wafers 7 are iI! Basket 1 to rt
5 to and from the CVD apparatus 1. This fork 14 is formed to loosely fit into a groove 16 formed in the longitudinal direction at the bottom of the basket 15, and is connected to the transfer port 20 at the rear end of the reaction tube 3 and the reserve. Transferring the basket 13 into these tubes 3.4 through the wafer transfer port 19 at the rear end of the heating tube 4;
The structure is such that the wafer 7 can be placed inside the CVD apparatus t.

Note that the reference numeral 18 in the figure indicates the wafer transfer port 1 of the preheating tube 4.
A cap for sealing the preheating tube 4 by contacting the preheating tube 9 is shown.

Next, the present invention will be explained in detail.

In the embodiment described above, first, with the gate valve 2 closed, the reaction tube 3 is heated by the reaction tube heater 5 to maintain the vapor phase growth temperature, and at the same time, the predictive heating tube heater 6 is used to preheat the reaction tube 3. The tube 4 is heated and the temperature is adjusted to a temperature such as 600° C. that will not cause distortion of the wafer 7 when the wafer 7 is placed into the preheating tube 4 from the outside.

Then, the cap 18 attached to the wafer transfer port 19 at the rear end of the preheating tube 4 is removed, and the basket 15 holding the plurality of wafers 7 is placed on the fork 14 and carried into the preheating tube 4. ), then remove the fork 14 from the basket 15 and open the wafer transfer port 1 of the preheating tube 4.
Attach the cap 18 to 9.

In this state, from the exhaust port 12 to the inside of the preheating tube 4.

At the same time, the air is removed from the wafer 7, and nitrogen gas is supplied from the inert gas supply port 13, and the wafer 7 is placed in an inert gas atmosphere at normal pressure to perform preheating (FIG. 2b).

Next, the cap 18 and the gate valve 2 are opened, and the basket 15 is transported into the reaction tube 3 using the fork 14 (c in the same figure), and then the fork 14 is removed and the gate valve 2 is closed again (d in the same figure). ).

In this state, since the temperature difference between the reaction tube 3, the preheating tube 4, and the wafer 7 is small, almost no air convection occurs within this tube, causing distortion of the wafer 7 and damage to the CVD film attached to the inner wall of the reaction tube 3. No peeling occurs.

The wafer 7 is heated in the reaction tube 3, gradually rising from the preheated state, and finally reaches the vapor phase growth temperature, for example 800°C.
reach.

Here, air is removed from the exhaust port 8 at the tip of the reaction tube 3 to create a reduced pressure state, and a reaction gas is supplied from the reaction gas supply port 10 of the reaction tube 3. CVDlF2, such as a 5hos film, a PSG film, etc., is grown in a vapor phase.

After forming CVDlF2 on the wafer 7, the exhaust from the gas chamber 8 is stopped to bring the inside of the reaction tube 3 to normal pressure, and in this state, the gate valve 2 is opened. Since the temperature difference between the tube 4 and the tube 4 is small, there is almost no gas convection within the tube, and the CVD film formed on the inner wall of the reaction tube 3 does not peel off, causing dust from the CVD film to adhere to the wafer 7. It is rare to do so.

Next, the basket 15 is transferred to the preheating tube 4 by performing a reverse operation to the above, and here the temperature of the preheating tube heater 6 is gradually lowered to approach the temperature of the outside air.

Thereby, when the wafer 7 is taken out from the preheating tube 4, no distortion occurs in the wafer 7.

In this case, the wafer 7 may be taken out while maintaining the temperature inside the preheating tube 4 at a value lower than the vapor growth temperature, for example, 600°C.

In the above-mentioned embodiment, the preheating tube 4 was set to normal pressure, but it is also possible to increase the exhaust volume to create a reduced pressure state. Although the conveyance was carried out by the fork 15, it is also possible to attach rollers to the preheating tube 4 and the reaction tube 3 and pull them with a wire, so that the preheating and vapor phase growth are performed continuously in a reduced pressure atmosphere. can.

〔Effect of the invention〕

As described above, according to the present invention, a preheating tube is provided for heating the wafer to a temperature below the vapor phase growth temperature before the wafer is introduced into the reaction tube, and the preheating tube is connected to the reaction tube so as to be able to communicate with the wafer. This not only prevents distortion of the wafer that occurs when installing the wafer in the reaction tube, but also prevents the film adhering to the inner wall of the reaction tube from peeling off due to gas convection caused by the temperature difference between the evaporator, outside air, and the reaction tube. Therefore, contamination of the wafer can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an apparatus showing an embodiment of the present invention; FIG. 2 is a detailed explanatory diagram of the present invention, FIG. 3 is a sectional view showing an example of a conventional device. (Explanation of symbols) 1...CVD device, 2...gate pulp, 3... reaction tube, 4... Preheating tube, 5...Reaction tube heater, 6... Heater for preheating tube, 7... Wafer, 14...fork, 15...basket, 18...cap, 19.20...Wafer transfer port.

Claims (1)

[Claims] A semiconductor wafer (7) is heated to a vapor phase growth temperature and a reactive gas is added to the wafer (7) under a reduced pressure atmosphere.
) a reaction tube (3) for forming a CVD film on the reaction tube (3); and a preparatory device connected to the reaction tube (3) and heating the wafer (7) at a temperature below the vapor phase growth temperature before transferring the wafer (7) to the reaction tube (3). It is characterized by comprising a heating tube (4) and a gate pulp (2) interposed between the preheating tube (4) and the reaction tube (3) to open and close the pipeline in an airtight manner. CVD equipment for semiconductor devices.