JPH0593274A - Vertical CVD film forming method and apparatus - Google Patents

Abstract

PURPOSE:To form a CVD film excellent in intra- and inter-surface uniformity on a wafer by supplying a gaseous reactant heated by the heating part of a feed pipe on plural wafers placed on a boat from below the wafers. CONSTITUTION:A boat 3 on which plural wafers 2 are placed on one another is inserted into the reaction furnace 1 consisting of an outer tube 1A and an inner tube 1B along with its boat cap 8 and a cap 9. The wafer 2 is heated to a specified temp. by a heater 4 arranged outside the furnace, and a gaseous reactant is introduced into the lower part of the boat 3 from a gaseous reactant feed pipe 7 to form a CVD film on the wafer 2. In this vertical CVD film forming method, the gaseous reactant in the pipe is heated by the heater 4 at the heating part 7A adjacent to the horizontal part 7B of the feed pipe 7 and then supplied through a discharge part 7C. Consequently, the gaseous reactant is not cooled in the boat 3, and the intra- and inter-wafer surface uniformity of the CVD film is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention inserts a boat on which a wafer is placed in a reaction furnace, heats the wafer by a heater provided outside the reaction furnace, and supplies a reaction gas into the reaction furnace to supply the wafer. The present invention relates to a vertical CVD film forming method and apparatus for forming a CVD film.

[0002]

2. Description of the Related Art In a vertical CVD apparatus, the uniformity of a CVD film on a wafer surface or between wafer surfaces is affected by the amount of reaction gas, reaction pressure and furnace temperature. The temperature stability is a major factor. However, when the reaction gas supplied into the furnace is not sufficiently heated, the temperature inside the furnace, particularly the temperature in the lower part of the reaction furnace becomes unstable, leading to deterioration of uniformity.

FIG. 5 is a sectional view showing the structure of the main part of a first example of a conventional method and apparatus. In this first conventional example, a boat 3 on which a wafer 2 is placed is inserted into a reaction furnace 1 composed of an outer tube 1A and an inner tube 1B together with the boat cap 8 and the cap 9, and a heater is provided outside the reaction furnace 1. 4, the wafer 2 is heated and the reaction gas is directly supplied into the reaction furnace 1 from a gas supply port 6 provided in a flange 5 below the reaction furnace 1 and connected to a pipe (not shown).

FIG. 6 is a sectional view showing the structure of the main part of a second example of the conventional method and apparatus. The second conventional example has a configuration in which a tubular heater 10 is connected to the gas supply port 6 in the first conventional example.

[0005]

As described above, CVD
The uniformity of the film within the wafer surface is greatly influenced by the stability of the temperature inside the furnace, and especially the SiH ₂ Cl ₂ —N ₂ O based SiO ₂
It is necessary to raise the temperature of the lower part of the reaction furnace in order to obtain good uniformity of the oxide film across the wafer. Then the first
In the conventional example, since the reaction gas having a lower temperature is supplied to the lower part of the reaction furnace 1 from the gas supply port 6, the reaction temperature in the lower part of the reaction furnace becomes unstable due to the influence, and as a result, the wafer surface of the lower part becomes lower. Inferiority in the inside and uniformity between wafer surfaces, resulting in the productivity of the CVD process in the LSI manufacturing process,
There is a problem that it leads to a decrease in yield.

Further, in the second conventional example, since the reaction gas is heated by the cylindrical heater 10 and supplied to the lower portion of the reaction furnace 1, the instability of the reaction temperature in the furnace is improved as compared with the first conventional example. However, the atmosphere temperature is affected by the fact that the flange 5 provided with the gas supply port 6 is water-cooled and the distance to the wafer 2 is long in order to prevent seizure, and the temperature of the reaction gas is lowered sufficiently. There is a problem that it is not possible to achieve such effects.

[0007]

In order to solve the above-mentioned problems, the method of the present invention is arranged such that a boat 3 on which a plurality of wafers 2 are mounted is inserted into a reaction furnace 1 as shown in FIG. Vertical CVD film formation for heating each wafer 2 by an external heater 4 and supplying reaction gas from a gas supply port 6 provided in a flange 5 at the bottom of the reaction furnace 1 to form a CVD film on each wafer 2. In the method, the reaction gas is introduced into a reaction gas supply pipe 7 connected to the gas supply port 6, the reaction gas is heated by a reaction gas heating unit 7A heated by the heater 4, and is discharged to a lower portion of the boat 3. It is characterized by

In order to solve the same problem, the apparatus of the present invention has a boat 3 having a plurality of wafers 2 mounted in a reaction furnace 1 as shown in FIG. 1, and a heater 4 provided outside the reaction furnace 1.
In the vertical CVD apparatus that heats each wafer 2 by using the above-mentioned method and supplies a reaction gas from a gas supply port 6 provided in a flange 5 below the reaction furnace 1 to generate a CVD film on each wafer 2, A reaction gas supply pipe 7 having a reaction gas heating portion 7A and a pipe end located below the boat 3 is connected to the gas supply port 6.

[0009]

With this structure, the reaction gas is introduced into the reaction gas supply pipe 7 through the gas supply port 6 provided in the flange 5 at the bottom of the reaction furnace 1 and sufficiently heated by the reaction gas heating section 7A. As a result, the reaction temperature is stabilized at the lower part of the reaction furnace 1 as a result of being led out from the pipe end located below the boat 3.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of the principal part of one embodiment of the method and apparatus of the present invention, and FIG. 2 is an explanatory view showing a first example of a reaction gas supply pipe used in this embodiment. In FIG. 1, the reactor is composed of an outer tube 1A and an inner tube 1B. A boat 3 having a large number of wafers 2 placed in the reaction furnace 1 is attached to the boat cap 8 and the seal cap 9
It is installed with.

A large number of wafers 2 mounted on the boat 3 are heated by a heater 4 provided outside the reaction furnace 1, and a reaction gas is supplied from a gas supply port 6 provided on a flange 5 below the reaction furnace 1. A CVD film is formed on each wafer 2.

In this embodiment of the vertical CVD film forming apparatus, the reaction gas supply pipe 7 having the reaction gas heating portion 7A heated by the heater 4 and having the pipe end facing downward below the boat 3 is used. It is connected to the gas supply port 6, and the connecting portion of the reaction gas supply pipe 7 to the gas supply port 6 is a horizontal portion 7B. 7C is a lead-out portion for leading the reaction gas downward from the boat 3.

The reaction gas is introduced into the reaction gas supply pipe 7 through the gas supply port 6 provided in the flange 5 at the lower part of the reaction furnace 1, passes through the horizontal portion 7B, is sufficiently heated by the reaction gas heating portion 7A, and is led out through the outlet portion 7C. After that, it is led out from the pipe end below the boat 3, and the reaction temperature in the lower part of the reaction furnace 1 is prevented from lowering, so that the reaction temperature is stabilized.

FIG. 3 is an explanatory view showing a second example of the reaction gas supply pipe used in FIG. The reaction gas heating portion 7A of the reaction gas supply pipe 7 is the same as that shown in FIG. 2 except that it has a vertical portion 7A ₁ and a horizontal portion 7A ₂ . As described above, the reaction gas heating unit 7A can have a free shape with a vertical (vertical) direction portion and a horizontal (horizontal) direction portion, and has no effect on the heating of the reaction gas.

A large number of wafers 2 were placed on the boat 3, and a CVD film was formed on the wafer surface under various conditions and evaluated. The uniformity of the film was evaluated by measuring the film thickness of the monitor wafer in the mounted wafer with an ellipsometer and calculating the value. As shown in FIG. 4, the film thickness measurement points were set at 5 points from the wafer periphery, that is, 4 points of positions T, L, O, and R and 5 points of the central C point. The uniformity within the wafer surface was calculated by the following equation (1). {(Maximum value-minimum value) / 2} / average value × 100 ... (1)

Further, the uniformity between the wafer surfaces was calculated by using Equation 1 after calculating the average value of the entire wafer from the average value of each wafer. (Example _{1) SiH 2 Cl 2 -N 2} O system formed of an oxide film reaction gas SiH ₂ Cl _2, the N ₂ O fed to the reaction furnace,
An oxide film (SiO ₂ ) was formed on the surface of the wafer placed on the boat. CVD film forming conditions (a) Reaction gas flow rate (CCM) SiH ₂ Cl ₂ : 10
0, N ₂ O: 100 (b) Boat pitch 9 mm (c) Reaction pressure (Pa) 50 (d) Reaction time (deposition time) 30'00 ″ Evaluation results are shown in Table 1.

[0017]

[Table 1]

As is apparent from Table 1 above, it is understood that the uniformity of the CVD film according to this embodiment is improved as compared with the first and second conventional examples.

(Example 2) Formation of SiH ₂ Cl ₂ -N ₂ O-based nitride film Reaction gases SiH ₂ Cl ₂ and N ₂ O were supplied into the reaction furnace and the nitride film (Si ₃ N ₄ ) was placed on a boat. Formed on the surface of the formed wafer. CVD film forming conditions (a) Reaction gas flow rate (CCM) SiH ₂ Cl ₂ : 4
0, N ₂ O: 320 (b) Boat pitch 5 mm (c) Reaction pressure (Pa) 30 (d) Reaction time 28′30 ″ Evaluation results are shown in Table 2.

[0020]

[Table 2]

As is clear from Table 2 above, it is understood that the uniformity of the CVD film according to this embodiment is improved as compared with the first and second conventional examples.

As can be seen from the above-mentioned experiments, the present embodiment has a significant effect in that the uniformity of the CVD film in the wafer surface and between wafer surfaces is significantly improved as compared with the conventional example.
Further, this also contributes to improvement in productivity and yield in the CVD process of the LSI manufacturing process.

[0023]

As described above, according to the present invention, the reactor 1
The reaction gas is introduced into the reaction gas supply pipe 7 connected to the gas supply port 6 provided in the lower flange 5 and heated by the reaction gas heating unit 7A heated by the heater 4 to heat the reaction gas to the lower portion of the boat 3. Since the vertical CVD film forming method and apparatus are derived, the reaction temperature in the lower part of the reaction furnace 1 is prevented from lowering, so that the reaction temperature can be stabilized, and the uniformity of the CVD film in the wafer surface and between wafer surfaces can be improved. Can be increased.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a main part of an embodiment of a method and device of the present invention.

FIG. 2 is an explanatory diagram showing a first example of a reaction gas supply pipe used in this embodiment.

FIG. 3 is an explanatory view showing a second example of the reaction gas supply pipe used in FIG.

FIG. 4 is a CVD produced on the surface of a wafer according to the present invention.
It is explanatory drawing which shows the measurement point of a film | membrane.

FIG. 5 is a cross-sectional view showing a configuration of a main part of a first example of a conventional method and apparatus.

FIG. 6 is a cross-sectional view showing a configuration of a main part of a second example of a conventional method and apparatus.

[Explanation of symbols]

 1 Reactor 2 Wafer 3 Boat 4 Heater 5 Flange 6 Gas Supply Port 7 Reaction Gas Supply Pipe 7A Reaction Gas Heating Section 7B Horizontal Section 7C Derivation Section

Claims (3)

[Claims] 1. A plurality of wafers (2) in a reaction furnace (1).
A boat (3) on which is mounted is inserted, and each wafer (2) is heated by a heater (4) provided outside the reaction furnace (1) and provided on a flange (5) below the reaction furnace (1). In the vertical CVD film forming method for supplying a reaction gas from the gas supply port (6) to generate a CVD film on each wafer (2), a reaction gas supply pipe ( A vertical CVD film, characterized in that the reaction gas is introduced into 7) and the reaction gas is heated by the reaction gas heating section (7A) heated by the heater (4) and discharged to the lower part of the boat (3). Generation method. 2. A plurality of wafers (2) in a reaction furnace (1).
A boat (3) on which is mounted is inserted, and each wafer (2) is heated by a heater (4) provided outside the reaction furnace (1) and provided on a flange (5) below the reaction furnace (1). In a vertical CVD apparatus for producing a CVD film on each wafer (2) by supplying a reaction gas from the provided gas supply port (6),
The reaction gas heating section (7) heated by the heater (4)
A vertical CVD film forming apparatus comprising a reaction gas supply pipe (7) having the pipe end (A) located below the boat (3) and connected to the gas supply port (6). 3. The vertical CVD film forming apparatus according to claim 2, wherein a connecting portion of the reaction gas supply pipe (7) to the gas supply port (6) is a horizontal portion (7B) and a pipe end is directed downward.