Semiconductor manufacturing apparatus including temperature control mechanism

Abstract

A semiconductor manufacturing apparatus includes a furnace having a tubular body with inner and outer tubular members. A boat having wafers mounted thereon is positioned inside the inner tubular member. temperature control inside the tubular body is provided by a thermocouple device located between the inner and outer tubular members. A mixture of dichlorosilane gas and ammonium gas formed by a mixing nozzle at a temperature which is lower than the temperature in the tubular body is supplied to the wafers from positions juxtaposed with the wafers mounted on the boat.

Description

The furnace employed in the apparatus shown in FIGS. 3-8 is generally referred to as a hot wall type.

As shown in FIG. 3, a semiconductor manufacturing apparatus having a vertical type LP-CVD device according, to the invention comprises a furnace. The furnace includes an outer tubular member 7, an inner tubular member 8 and a heater 14 provided around the periphery of the outer tubular member 7.

A boat 15 having wafers 10 mounted thereon is accommodated in the inner tubular member 8 and supported by a furnace port flange 9 so that the boat 15 can be moved into and out of the furnace by raising and lowering the furnace port flange 9 by an elevator not shown in the drawing.

A thermocouple cover 24 is provided between said inner tubular member 8 and the outer tubular member 7 for controlling the temperature in the furnace. A heat screening plate 25 is provided between the flange 9 and the boat 15. A nozzle 12 for supplying dichlorosilane gas and a nozzle 13 for supplying ammonium gas into the furnace are arranged at the furnace port. A mixing gas nozzle 21 is provided along the longitudinal direction of the boat 15 for supplying a mixture of dichlorosilane gas and ammonium gas to the wafers located near the bottom of said inner tube 8. Reference numeral 23 in FIG. 3 denotes a gas nozzle for blowing nitrogen gas. According to the present invention, the gas mixing operation is conducted at a low temperature range and the temperature in the furnace is evenly maintained and at a constant level. Thermocouples in the thermocouple cover 24 measure the temperature in the furnace at four predetermined points and control the temperature so that a temperature flat condition is maintained in the furnace. FIG. 4A is a plan view of the mixing gas nozzle 21 and FIG. 4B is a side view thereof. Dichlorosilane gas is supplied from gas port 211 21₁ and ammonium gas is supplied from gas, port 212 21₂ , which are then mixed in the mixing gas nozzle 21 so that the mixed gas is blown out of holes 22. The holes 22 are arranged within the upper half of mixing gas nozzle tube 21, which is juxtaposed with the upper flat of the boat.

It should be noted that the gas ports 211 21₁ and 212 21₂ are located near the furnace port flange 9 and operate at a low temperature within the temperature range between 30° and 180°C for mixing with a view to prevent clogged nozzles from taking place by suppressing pyrolysis of dichlorosilane gas as the gas mixing operation is conducted at a low temperature within the range indicated above.

For the purpose of comparison, silicon nitride films were formed by using a vertical type LP-CVD device as shown in FIG. 3, where a temperature gradient was maintained in the furnace and dichlorosilane gas and ammonium gas were respectively supplied from the dichlorosilane gas nozzle 12, the ammonium gas nozzle 13 and the mixing gas nozzle 21 simultaneously for reaction.

FIGS. 5 and 6 show the degree of evenness of the films formed by a vertical type LP-CVD device of the prior art (FIG. 2) and that of the films produced by a vertical type LP-CVD device according to the invention (FIG. 3). In these graphic illustrations, dotted line A represents the films formed by a vertical type LP-CVD device of the prior art having no temperature gradient and dotted line B represents the films formed by a vertical type LP-CVD device of the present invention having no temperature gradient. It is obvious from these graphic illustrations that silicon nitride films having a nearly identical thickness are formed by an apparatus comprising a vertical LP-CVD device according to the invention.

FIG. 7 is a table showing the degree of evenness of thickness of the silicon, nitride film produced by a horizontal type LP-CVD device of the prior art (FIG. 1) and those produced by a vertical type LP-CVD device of the invention. From the table of FIG. 7, it is obvious that a vertical type LP-CVD device of the invention can produce silicon nitride films having a thickness which is almost identical to the horizontal type LP-CVD device of the prior art having a temperature gradient. It should be noted that FIG. 7 shows dispersions of thickness of the films prepared by an apparatus charged with 100 five-inch wafers. The conditions of film depositon for a vertical type LP-CVD device of the invention are as follows: growth temperature: 780°C flat, growth pressure: 0.15 Torr, dichlorosilane gas flow rate: 90 cc/min, ammonium gas flow rate: 450 cc/min. The conditions for a horizontal type LP-CVD of the prior art are as follows: growth temperature: 770°-780°-790°C, growth pressure: 0.35 Torr, dichlorosilane gas flow rate: 37 cc/min, ammonium gas flow rate 160 cc/min.

FIG. 8 shows another embodiment of the present invention comprising a horizontal type LP-CVD device. As in the case of the above embodiment, this embodiment differs from a horizontal type LP-CVD device of the prior art (FIG. 1) in that it comprises a mixing gas nozzle 21 and reactions are conducted under a temperature flat condition in the furnace. The rest of the reaction conditions as well as the effects of this embodiment are similar to those of the above described embodiment.

It will be obvious that various alterations and modifications can be made to the above embodiments within the scope of the present invention. For example, while dichlorosilane gas and ammonium gas are introduced separately into the furnace in the above embodiments, they can be introduced after having been mixed with each other. It should also be noted that the ratio of the flow rate of dichlorosilane gas and that of ammonium gas is advantageously found between 1:5 and 1:15.

Claims

1. A semiconductor manufacturing apparatus comprising:

furnace means including heating means and a tubular body comprising an inner tubular member and an outer tubular member, the tubular body having an inlet region at a first end of the tubular body, and a furnace port flange connected to the tubular body at a second end of the tubular body, and the heating means being provided around the periphery of the outer tubular member;

boat means removably inserted in the tubular body;

a plurality of wafers provided on the boat means each having a thin film formed thereon;

temperature control means provided in the tubular body between the inner tubular member and the outer tubular member for controlling the temperature therein, to maintain the circumference of the boat means at a uniform temperature;

mixed gas supply means provided in the furnace means for supplying a mixture of dichlorosilane gas and ammonium gas, mixed at a temperature lower than the uniform temperature in the tubular body, into the tubular body adjacent wafers disposed nearest the inlet region of the tubular body; and

gas supply means for separately supplying dichlorosilane gas and ammonium gas into the tubular body adjacent wafers disposed nearest the furnace port flange.

2. A semiconductor manufacturing apparatus according to claim 1, wherein the ratio of the flow rate of dichlorosilane gas and that of ammonium gas for producing mixed gas is between 1:5 and 1:15.

3. The semiconductor manufacturing apparatus according to claim 1, wherein the temperature for mixing dichlorosilane and ammonium gas is about 30° to about 180°C

4. A semiconductor manufacturing apparatus comprising:

furnace means including heating means and a tubular body having an inner tubular member and an outer tubular member, the tubular body having a furnace port flange connected to one end of the tubular body, and the heating means being provided around the outer periphery of the outer tubular member;

boat means removably inserted in the tubular body;

a plurality of wafers provided on the boat means each having a thin film formed thereon;

temperature control means provided in the tubular body between the inner tubular member and the outer tubular member for controlling the temperature therein to maintain at least a portion of the tubular body at a uniform temperature;

mixed gas supply means provided in the furnace means for supplying a mixture of dichlorosilane gas and ammonium gas, mixed at a temperature lower than the uniform temperature in the tubular body, into the tubular body adjacent wafers disposed nearest the inlet region of the tubular body.

5. A semiconductor manufacturing means according to claim 4 wherein the ratio of the flow rate of dichlorosilane gas and that of ammonium gas for producing mixed gas is between 1:5 and 1:15.

6. The semiconductor manufacturing apparatus according to claim 4, wherein the temperature for mixing the dichlorosilane gas and the ammonium gas is between about 30° and about 180°C

7. The semiconductor manufacturing apparatus of claim 4, further comprising gas supply means for separately supplying dichlorosilane gas and ammonium gas into the tubular body adjacent wafers disposed nearest the furnace port flange.

8. A semiconductor manufacturing apparatus comprising:

hot wall furnace means including heating means for producing a first temperature region and a second temperature region inside the furnace means, the second temperature region being lower in temperature than the first temperature region;

boat means, removably inserted in the first temperature region of the furnace means, for holding a plurality of wafers only in the first temperature region;

temperature control means, including a plurality of temperature sensing elements arranged inside the furnace means, for maintaining a uniform temperature in the first temperature region;

gas supply means for supplying a first reactive gas and a second reactive gas into the second temperature region of the furnace means; and

mixed gas supply means for mixing, in the second temperature region, the first reactive gas and the second reactive gas together and for supplying the resultant mixed gas toward a portion of the plurality of wafers in the first temperature region of the furnace means. 9. The semiconductor manufacturing apparatus according to claim 8, wherein the plurality of temperature sensing elements are thermocouples.

10. The semiconductor manufacturing apparatus according to claim 8, wherein the first and second gases react to each other and are supplied toward the plurality of wafers to form a film on the plurality of wafers. 11. The semiconductor manufacturing apparatus according to claim 8, wherein the first and second gases are mixed together at a temperature suppressing pyrolysis of the first gas. 12. The semiconductor manufacturing apparatus according to claim 8, wherein the mixed gas supply means includes a nozzle having a plurality of openings. 13. The semiconductor manufacturing apparatus according to claim 8, wherein the first gas is dichlorosilane gas, and the second gas is ammonium gas. 14. The semiconductor manufacturing apparatus according to claim 13, wherein the ratio of the flow rate of the dichlorosilane gas to that of the ammonium

gas is between 1:5 and 1:15. 15. The semiconductor manufacturing apparatus according to claim 13, wherein the temperature at which the dichlorosilane gas and the ammonium gas are mixed together is between about 30°C and about 180°C 16. The semiconductor manufacturing apparatus according to claim 8, wherein the gas supply means separately supplies the first and second gases into the second temperature region of the furnace means. 17. The semiconductor manufacturing apparatus according to claim 8, wherein the gas supply means mixed the first and second gases together and supplies the resultant mixed gas to the second temperature region of the furnace means. 18. A semiconductor manufacturing apparatus comprising:

hot wall furnace means including heating means for producing a first temperature region and a second temperature region inside the furnace means, the second temperature region being lower in temperature than the first temperature region;

boat means, removably inserted into the first temperature region of the furnace means, for holding a plurality of wafers only in the first temperature region;

temperature control means, heated by the heating means and including a plurality of temperature sensing elements arranged inside the furnace means, for maintaining a uniform temperature in a region surrounding the plurality of wafers; and

mixed gas supply means for mixing, in the second temperature region, a first reactive gas and a second reactive gas together and for supplying the resultant mixed gas toward a portion of the plurality of wafers.

19. The semiconductor manufacturing apparatus according to claim 18, wherein the plurality of temperature sensing elements are thermocouples. 20. The semiconductor manufacturing apparatus according to claim 18, wherein the first and second gases react to each other and are supplied toward the plurality of wafers to form a film on the plurality of wafers. 21. The semiconductor manufacturing apparatus according to claim 18, wherein the second gas serves to retard pyrolysis of the first gas. 22. The semiconductor manufacturing apparatus according to claim 18, wherein the first and second gases are mixed together at a temperature which

suppresses pyrolysis of the first gas. 23. The semiconductor manufacturing apparatus according to claim 18, wherein the mixed gas supply means includes a nozzle having a plurality of openings. 24. The semiconductor manufacturing apparatus according to claim 18, wherein the first gas is dichlorosilane gas, and the second gas is ammonium gas. 25. The semiconductor manufacturing apparatus according to claim 24, wherein the ratio of the flow rate of the dichlorosilane gas to that of the ammonium gas is between 1:5 and 1:15. 26. The semiconductor manufacturing apparatus according to claim 24, wherein the temperature at which the dichlorosilane gas and the ammonium gas are mixed together is between about 30°C and about 180°C 27. A semiconductor manufacturing method for use in a semiconductor manufacturing apparatus comprising: a hot wall furnace having a gas introducing port, a gas exhaust port, and a heater; a boat inserted into the furnace and capable of holding a plurality of wafers; and temperature control means inside the furnace, the semiconductor manufacturing method comprising the steps of:

causing the temperature control means to control the heater to maintain a first temperature region surrounding the plurality of wafers at a uniform temperature sufficiently high to perform wafer processing;

mixing a first reactive gas and a second reactive gas together in a second temperature region inside the furnace at a temperature lower than the first temperature region so as to obtain a mixed gas, said first and second reactive gases reacting with each other to form the mixed gas; and

supplying the mixed gas toward the plurality of wafers in the first temperature region such that the mixed gas reaches at least the vicinity

of the plurality of wafers. 28. The semiconductor manufacturing method according to claim 27, wherein the first gas is dichlorosilane gas, and the second gas is ammonium gas. 29. The semiconductor manufacturing method according to claim 28, wherein the dichlorosilane gas before mixing is maintained at a temperature within a range of between about 30°C and about 180°C 30. The semiconductor manufacturing method according to claim 28, wherein the ratio of the flow rate of the dichlorosilane gas to that of the ammonium gas is between 1:5 and 1:15. 31. The semiconductor manufacturing method according to claim 27, wherein the mixing step is performed using a nozzle having a plurality of openings.