JPH02254714A - Semiconductor manufacturing device - Google Patents

Abstract

PURPOSE:To make it possible to form a film in uniform thickness and quality between wafers by a method wherein an inside reaction tube having an aperture is provided on the entrance side of a furnace, and reaction gas is flowed on the inner side and the entrance side of the furnace. CONSTITUTION:An inside reaction tube 3, having an aperture part 30 on the entrance side of a furnace, is provided and a wafer is placed in the reaction tube 3 ranging from the inner section of the furnace to the furnace entrance side. Reaction gas is fed into the inside reaction tube from a gas jetting hole 7, and temperature is controlled in such a manner that the temperature in the furnace becomes uniform ranging from the inner part of the furnace to the furnace entrance section. To be more precise, the gas is flowed not only from the center position of the furnace to the inner part of the furnace, but also from the center position of the furnace to the furnace entrance side by the action of the aperture part 30 provided in the inside reaction tube 3. As a result, almost the same quantity of gas can be given to each wafer 5 by the stream of gas flowing in two directions opposing with each other. Consequently, the thickness of the wafer 5 can be made uniform without giving temperature gradient in the furnace.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a semiconductor manufacturing apparatus constituting an LP-CVD apparatus, and in particular to a semiconductor manufacturing apparatus for forming a polysilicon film or a silicon nitride film. Related to semiconductor manufacturing equipment.

(Prior art) In conventional LP-CVD equipment, when forming a polysilicon film or a silicon nitride film, the pressure inside the reaction tube is maintained at a reduced pressure of 20 to 50 (Pa), and the furnace opening side is Reactant gas is supplied into the furnace from. This reaction gas is discharged outside the furnace after passing through a plurality of wafers placed in the furnace.

For this reason, when the temperature inside the furnace is uniform, wafers placed near the furnace mouth are exposed to a larger amount of gas than wafers located at the back of the furnace, and the film is deposited on the wafers placed near the furnace mouth. The film thickness is thicker (
It will be formed. For this reason, in order to make the film thickness the same between wafers, a temperature gradient is usually provided in the furnace, and the temperature on the back side of the furnace is set higher than on the furnace opening side.

However, when creating a temperature gradient in the furnace like this,
Stress of polysilicon film and silicon nitride film,
Another disadvantage is that the grain size of the polysilicon film varies from wafer to wafer. This is because the stress of the polysilicon film and silicon nitride film depends on the growth temperature, and the grain size of the polysilicon film increases as the growth temperature increases. The fact that the film characteristics differ from wafer to wafer in this manner is a very undesirable phenomenon in the current manufacturing method in which a plurality of wafers are processed in the same process.

It is also known that instead of creating a temperature gradient in the furnace, multiple gas nozzles are installed to disperse the reaction gas and uniformly apply the gas to each wafer. The disadvantage is that it complicates the process.

(Issue II to be Solved by the Invention) This invention was developed in view of the above-mentioned circumstances. Conventionally, when a temperature gradient is created in the furnace, the film quality differs between wafers.
Another purpose is to provide a semiconductor manufacturing apparatus that can form a film with a simple structure and uniform film thickness and quality from wafer to wafer, by improving the structure that becomes complicated when using a dispersion gas nozzle. shall be.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a semiconductor manufacturing apparatus constituting an LP-CVD apparatus, which has an opening on the furnace mouth side.

An inner reaction tube, a wafer support means provided in the inner reaction tube on which a plurality of wafers are placed alternately from the back side of the furnace to the furnace mouth side, and a gas injection hole near the center of the second wafer support means. a gas supply means for supplying a reaction gas into the inner reaction tube from the gas ejection hole, and a temperature control for controlling the temperature in the furnace so that the temperature is uniform from the back side of the furnace to the front side of the furnace. The reaction gas is characterized in that the reactant gas flows from the ejection hole to the back side of the furnace, and from the ejection hole to the furnace mouth side of the furnace.

(Function) In this semiconductor manufacturing equipment, the reaction gas not only flows from the center of the furnace to the back of the furnace, but also flows from the center of the furnace to the furnace mouth due to the action of the openings provided in the inner reaction tube. It also flows. Thus, the two opposing directions of gas flow allow each wafer to be provided with approximately the same amount of gas.

Therefore, the thickness of the film formed on each wafer can be made uniform without creating a temperature gradient in the furnace, so it is possible to prevent variations in film quality caused by the temperature gradient.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a cross-sectional structure of a vertical LP-CVD apparatus according to an embodiment of the present invention. In the figure, l is a heater, and an outer tube (outer reaction tube) 2 is attached to the heater 1 so as to surround its inner peripheral surface. Inside the outer tube 2, an inner tube (inner reaction tube) 3 is arranged at a predetermined distance from the outer tube 2. As shown in FIG. 2, this inner tube 3 has a plurality of openings 30 in a portion corresponding to the furnace mouth side of this LP-CVD apparatus. A wafer boat 4 is arranged inside the inner tube 3. 20 A plurality of wafers 5 are placed in a row on the wafer boat 4 as shown in the figure.

The thermocouple protection tube 6 is a cover for a thermocouple for adjusting the temperature inside the furnace, and is arranged between the outer tube 2 and the inner tube 3. The gas nozzle 7 is for supplying a reactive gas to the wafers 5 in the inner tube 3, and has a gas ejection hole at a position corresponding to approximately the center of the wafer boat 4. The gas ejected into the furnace by the gas nozzle 7 is discharged to the outside from the exhaust port 8.

Further, 9 is a heat shield plate, and IO is a furnace mouth flange.

In this LP-CVD apparatus, when forming a polysilicon film on each wafer 5, silane gas is supplied by the gas nozzle 7 to approximately the center of the wafer boat 4 within the inner tube 3.

Then, as shown by the solid line arrow, this silane gas passes through the wafer 5 at the back of the furnace, passes between the outer tube 2 and the inner tube 3, and is discharged from the exhaust port 8. Due to the action of the opening 30, the gas passes through the wafer 5 on the furnace opening side, passes through the opening 30 of the inner tube 3, and is discharged from the exhaust port 8, as shown by the broken line arrow. In this way, gas flows not only in one direction from the furnace mouth side to the back side of the furnace as in the conventional case, but also in two directions that are opposite to each other. Note that the temperature inside the furnace at this time is controlled to be uniform by a thermocouple in the thermocouple retainer 3W6.

When a polysilicon film is formed in this way, 2
Since the amount of gas supplied to the wafers 5 by the directional gas flow is approximately the same on the furnace opening side and the furnace back side, the thickness of the deposited polysilicon film can also be made approximately uniform between the wafers. Furthermore, since there is no temperature gradient, the stress and grain size of the polysilicon film are the same for each wafer.

Further, when forming a silicon nitride film using this vertical LP-CVD apparatus, a mixed gas of dichlorosilane gas and ammonia gas may be supplied into the furnace from the gas nozzle 7. In this case as well, since there is no need to create a temperature gradient due to the flow of gas in two directions, it is possible to form a silicon nitride film with the same thickness and quality.

FIG. 3 shows a horizontal LP-CV according to a second embodiment of the present invention.
D shows the cross-sectional structure of the device. In the figure, 11 is a heater;
An outer tube (outer reaction tube) 12 is attached to this heater 11 so as to surround its inner peripheral surface.

Inside the outer tube 12, an inner tube (inner reaction tube) 13 is arranged at a predetermined distance from the outer tube 12. As shown in FIG. 4, this inner tube 13 has a plurality of openings 130 in a portion corresponding to the furnace mouth side of this LP-CVD apparatus.

A wafer boat 14 is arranged inside the inner tube 13. A plurality of wafers 15 are arranged in this wafer bow 14 as shown.

The thermocouple protection tube IB is a cover for a thermocouple for adjusting the temperature inside the furnace, and is arranged between the outer tube 12 and the inner tube 13. The gas nozzle 17 is for supplying a reactive gas to the wafer 15 in the inner tube 13, and a gas ejection hole is provided at a position corresponding to approximately the center of the wafer bow 14. The gas ejected into the furnace by the gas nozzle 17 is exhausted to the outside from the exhaust port 18.

Further, 19 is a furnace mouth flange.

This LP-CVD! When forming a polysilicon film on each wafer 15, silane gas is supplied from the gas nozzle 17 to approximately the center of the wafer boat 14 within the inner tube 13.

Then, this silane gas passes through the wafer 15 at the back of the furnace and then into the outer tube 12 as shown by the solid arrow.
and the inner tube 13 and is discharged from the exhaust port 18, and by the action of the opening 130 provided in the inner tube 13, the air is discharged from the inner tube 3 after passing through the wafer 15 on the furnace opening side as shown by the broken line arrow. Opening hole 1
30 and is discharged from the exhaust port 18. in this way,
Gas flows in two opposite directions. Note that the temperature inside the furnace at this time is controlled to be uniform by a thermocouple in the thermocouple protection tube 16.

When a polysilicon film is formed in this way, 2
Since the amount of gas supplied to the wafers 15 by the directional gas flow is approximately the same on the furnace opening side and the furnace back side, the thickness of the deposited polysilicon film can also be made approximately uniform between the wafers. Furthermore, since there is no temperature gradient, the stress and grain size of the polysilicon film are the same for each wafer.

Furthermore, when forming a silicon nitride film using this horizontal LP-CVD apparatus, a mixed gas of dichlorosilane gas and ammonia gas may be supplied into the furnace from the gas nozzle 17. In this case as well, there is no need to create a temperature gradient due to the flow of gas in two directions (therefore, the silicon nitride film can be formed so that the film thickness and film quality are uniform between wafers).

[Effects of the Invention] As described above, according to the present invention, it is possible to form a polysilicon film or a silicon nitride film with a simple structure and uniform film thickness and film quality among wafers.

[Brief explanation of drawings]

1 is a cross-sectional structural diagram showing a semiconductor manufacturing apparatus according to a first embodiment of the present invention, FIG. 2 is a diagram showing an inner tube provided in the semiconductor manufacturing apparatus shown in FIG. 1, and FIG.
This figure is a sectional structural view showing a semiconductor manufacturing apparatus according to a second embodiment of the present invention, and FIG. 4 is a diagram showing an inner tube provided in the semiconductor manufacturing apparatus shown in FIG. 3. 1... Heater, 2... Outer tube, 3...
Inner tube, 4... Wafer boat, 5...
Wafer, 6... Thermocouple protection tube, 7... Gas nozzle, 8... Exhaust port, 9... Heat shield plate, 10... Furnace mouth flange. Applicant's agent Patent attorney Takehiko Suzue Figure 2

Claims (1)

[Claims] In the semiconductor manufacturing equipment that constitutes the LP-CVD equipment,
An inner reaction tube having an opening on the furnace mouth side, a wafer support means provided in the inner reaction tube and on which a plurality of wafers are placed from the furnace back side to the furnace mouth side, and the wafer support means a gas supply means having a gas outlet near the central position of the reactor, and supplying a reaction gas from the gas outlet into the inner reaction tube; and a temperature control means for controlling the temperature so that Semiconductor manufacturing equipment.