JP3072723B2 - Semiconductor device manufacturing method and manufacturing apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a semiconductor device suitable for forming a polycrystalline silicon film or the like on a wafer, and more particularly to a method for manufacturing a semiconductor device with an improved product yield. And a manufacturing apparatus.

[0002]

2. Description of the Related Art In order to form a polycrystalline silicon film on a wafer, for example, a film forming apparatus such as a low pressure CVD apparatus is used. Various methods and apparatuses for manufacturing semiconductor devices have been studied and proposed in order to keep the quality of the formed film constant (Japanese Patent Application Laid-Open Nos. 59-48931 and 60-31224). Gazette, JP-A-2-394
No. 25). In the method of manufacturing a semiconductor device described in JP-A-59-48931, a thermocouple is arranged in a chamber into which a wafer is inserted in order to form a thermal oxide film having a constant thickness. The temperature inside the chamber is measured and fed back to keep the temperature inside the chamber uniform.

In the method of manufacturing a semiconductor device described in Japanese Patent Application Laid-Open No. 60-31224, a thermocouple is provided outside a chamber into which a wafer is inserted in order to uniformly diffuse impurities. The temperature is measured, and the components of the gas supplied into the chamber are adjusted according to the temperature measured by the thermocouple.

Further, in the apparatus for manufacturing a semiconductor device described in Japanese Patent Application Laid-Open No. 2-39425, the chamber has a double structure in order to more accurately measure the temperature in the chamber. Is provided with a thermocouple, and this portion is purged with nitrogen.

[0005] As is also the object of control in these prior arts, one of the factors affecting the film quality is the film formation temperature. When the film forming temperature fluctuates during the film forming process, the characteristics of the formed film are significantly changed.
For this reason, maintaining a constant film formation temperature is extremely important in manufacturing a semiconductor device.

A conventional semiconductor device manufacturing apparatus provided with means for controlling the film forming temperature will be described. FIG. 3 is a schematic view showing a conventional semiconductor device manufacturing apparatus. A tube 25 into which a wafer 30 is inserted is provided in a conventional semiconductor device manufacturing apparatus. Note that the wafer 30 is
And inserted into the tube 25. Tube 25
Is connected to one end of an exhaust pipe 27.
Is connected to a vacuum pump 28 at the other end. A tube temperature sensor 22 that measures the temperature of the tube 25 is provided outside the tube 25, and the tube temperature sensor 22 is connected to a control device 23. Further, a heater 24 for heating the inside of the tube 25 is connected to the control device 23. The tube 25 is provided with an inlet 29 into which a process gas 31 such as SiH ₄ gas is introduced.

In the conventional semiconductor device manufacturing apparatus configured as described above, after the wafer 30 is inserted into the tube 25, a process gas 31 is introduced into the tube 25 from an inlet 29, and the vacuum pump 28 Tube 2
The pressure inside 5 is adjusted to a predetermined pressure. Next, while the temperature of the tube 25 is measured by the tube temperature sensor 22, the heater 24 is controlled by the controller 23 based on this temperature until the temperature of the tube 25 reaches a predetermined temperature, so that the inside of the tube 25 is heated. You. At this time, the temperature inside the tube 25 substantially matches the temperature measured by the tube temperature sensor 22. Then, a polycrystalline silicon film starts to grow on wafer 30.

Thereafter, the temperature of the tube 25 is measured by the tube temperature sensor 22, and the polycrystalline silicon film is grown on the wafer 30 while the heater 24 is controlled by the controller 23 so that the temperature of the tube 25 becomes constant. Keep doing.

[0009]

However, the film quality of the film formed on the semiconductor device manufactured by the conventional semiconductor device manufacturing apparatus or manufacturing method is not sufficiently stable, and the yield of the semiconductor device is low. There is a problem.

[0010] When a film is formed by heating the inside of the chamber by a heating device such as a heater or a lamp from the outside of the chamber, not only the film is formed on the wafer but also deposits are deposited on the inner surface of the chamber. Then, a large amount of deposits are deposited on the inner surface of the chamber as the film formation proceeds, so that heat from the heating device is less likely to be transmitted to the inside of the chamber.

A thermocouple is provided outside the chamber as described in JP-A-60-31224 or JP-A-2-39425, or as in the manufacturing apparatus or manufacturing method shown in FIG. In some cases, the temperature inside the chamber is not accurately measured due to the accumulation of a large amount of deposits. FIG.
FIG. 4 is a graph showing the relationship between the growth time, the control temperature, and the process temperature in the conventional semiconductor device manufacturing apparatus shown in FIG. 3 with the horizontal axis representing the growth time and the vertical axis representing the temperature. In FIG. 4, a solid line indicates a control temperature, and a broken line indicates a process temperature. As shown in FIG. 4, the control temperature, which is the temperature of the tube 25,
2, the temperature is kept constant, but since the deposits are deposited on the inner surface of the tube 25, the process temperature on the surface of the wafer 30 on which the polycrystalline silicon film is formed decreases as the growth time increases. doing. As a result, the film quality of the polycrystalline silicon film becomes unstable. In particular, when a plurality of manufacturing apparatuses are used, the film quality between the manufacturing apparatuses is not constant.

As in the manufacturing method described in Japanese Patent Application Laid-Open No. 59-48931, it is conceivable to provide a temperature sensor inside the tube. In this case, as in the case where deposits are deposited on the inner surface of the tube, Deposits also accumulate on the temperature sensor. Therefore, as in the case where the temperature sensor is provided outside the chamber, the process temperature on the wafer surface cannot be kept constant.

When the conventional semiconductor device manufacturing apparatus shown in FIG. 3 is used, deposits are deposited at a thickness of about 2 μm per hour. Then, the thickness of the deposit is about 20 μm.
m, the wafer 30 peels off from the inner surface of the tube 25 and
, The yield decreases. For this reason, conventionally, the thickness of the deposited matter is controlled, and this thickness is 20 μm.
At time m, the tube 25 is cleaned to remove deposits such as polycrystalline silicon deposited on the inner surface of the tube. However, a complicated device or operation is required to control the thickness of the deposit.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a method and an apparatus for manufacturing a semiconductor device capable of suppressing a change in film quality of a formed film and improving a yield. Aim.

[0015]

A method of manufacturing a semiconductor device according to the present invention includes a step of forming a film on a wafer. In the method of manufacturing a semiconductor device, the step of forming the film includes inserting the wafer. Measuring the temperature of the gas exhausted from the tube, and controlling the temperature of the tube so that the temperature of the gas becomes constant.

Before the step of measuring the temperature of the gas, a step of setting the temperature of the tube to a first temperature at which the wafer is formed may be included.

Further, the step of controlling the temperature of the tube includes a step of measuring a second temperature of the tube.
The method may include a step of cleaning the tube when a difference between the second temperature and the first temperature reaches a predetermined value.

By determining the time to clean the tube based on the amount of temperature rise measured by the tube temperature sensor, the time to remove the deposits deposited on the inner surface of the tube can be reduced without requiring complicated equipment or operation. You can know.

The semiconductor device manufacturing apparatus according to the present invention comprises a tube into which a wafer is inserted, a tube temperature sensor for measuring the temperature of the tube, and an exhaust temperature sensor for measuring the temperature of gas exhausted from the tube. And a tube temperature control means for controlling the temperature inside the tube based on the temperature of the tube and the temperature of the gas.

In the present invention, while the temperature of the tube is measured by the tube temperature sensor, the tube temperature is raised by the tube temperature control means to the temperature at which the film is formed on the wafer. Then, the temperature of the gas exhausted from the tube when the temperature of the tube reaches the temperature at which the film is formed on the wafer is measured by the exhaust temperature sensor.
Thereafter, a film is formed on the wafer while the temperature in the tube is controlled by the temperature control means in the tube so that the temperature of the gas becomes constant. Since no deposits accumulate between the exhaust temperature sensor and the inside of the tube, if the temperature measured by the exhaust temperature sensor is constant, the temperature in the chamber is also constant. Therefore, a semiconductor device in which a change in film quality is suppressed is manufactured with a high yield.

The in-tube temperature control means may include a heating device for heating the tube, and a control device for controlling heat generated from the heating device.

Further, the control device may be connected to the tube temperature sensor and the exhaust gas temperature sensor.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of intensive experiments and research conducted by the present inventors to solve the above-mentioned problems, the temperature of a gas exhausted from a chamber is measured, and a heating device is set so that the temperature becomes constant. It has been found that by controlling the temperature, the process temperature on the wafer surface can be kept constant regardless of the thickness of the deposits deposited on the inner surface of the chamber.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing an apparatus for manufacturing a semiconductor device used in the method of the present embodiment. In this embodiment, a tube 5 into which the wafer 10 is inserted is provided. Note that the wafer 10 is a boat 6
And inserted into the tube 5. One end of an exhaust pipe 7 is connected to the tube 5, and the other end of the exhaust pipe 7 is connected to a vacuum pump 8. The exhaust pipe 7 is provided with an exhaust temperature sensor 1 for measuring the temperature of the gas exhausted from the tube 5. A tube temperature sensor 2 for measuring the temperature of the tube 5 is provided outside the tube 5.
Is provided. The exhaust gas temperature sensor 1 and the tube temperature sensor 2 are connected to the control device 3. Further, a heater 4 for heating the inside of the tube 5 is connected to the control device 3. The tube 5 is provided with an inlet 9 through which a process gas 11 such as SiH ₄ gas is introduced.

In the method of manufacturing a semiconductor device using the manufacturing apparatus of this embodiment configured as described above, first, the wafer 10 is placed on the boat 6 and these are inserted into the tube 5. Next, a SiH ₄ gas is introduced as the process gas 11 from the inlet 9 at a flow rate of, for example, 2 SLM into the tube 5
Introduce within. Then, the vacuum pump 8 is operated to increase the pressure in the tube 5 to a predetermined pressure, for example, 0.5 Torr.
To hold. Further, while the temperature of the tube 5 is measured by the tube temperature sensor 2, the heat generated from the heater 4 is controlled by the controller 3 so that the temperature becomes a predetermined temperature, for example, 600 ° C. Thereby, the inside of the tube 5 is heated. Since no deposit is deposited on the inner surface of the tube 5, the process temperature of the surface of the wafer 10 in the tube 5 is, for example, about 600 ° C. At this time,
The temperature T ₀ of the gas exhausted from the tube 5 is measured by the exhaust temperature sensor 1. Then, the polycrystalline silicon film starts growing on the wafer 10.

[0026] Thereafter, the temperature of the gas exhausted from the tube 5 continues measured by the exhaust temperature sensor 1, the temperature to be kept at a temperature T _0, the control unit 3 for controlling the heat generated from the heater 4 . In this state, the process gas 11 is continuously introduced into the tube 5 at a flow rate of, for example, 2 SLM, and the pressure inside the tube 5 is maintained at, for example, 0.5 Torr by the vacuum pump 8, thereby forming the polycrystalline silicon film. It is grown on the wafer 10.

In the method of this embodiment, between the exhaust gas temperature sensor 1 provided in the exhaust pipe 7 and the inside of the chamber 5,
Since no deposits are deposited, if the temperature of the gas passing through the exhaust temperature sensor 1 is kept constant, the temperature inside the chamber 5 is also kept constant. Figure 2 shows the growth time on the horizontal axis,
FIG. 5 is a graph showing the relationship between the growth time, the control temperature, and the process temperature in the method of the embodiment of the present invention, taking the temperature on the vertical axis. In FIG. 2, the solid line indicates the control temperature, and the dashed line indicates the process temperature. In the method of the present embodiment, as shown in FIG. 2, the control temperature, which is the temperature of the tube temperature sensor 2, is increased by the amount of the heat that is hardly transmitted by the deposit. Thus, the process temperature, which is the temperature of the surface of the wafer 10, can be kept constant. For this reason, the film quality of the manufactured semiconductor device is extremely stable, and the yield is improved.

Also, in the method of this embodiment, while the polycrystalline silicon film is grown on the wafer 10, deposits of about 2 μm are deposited on the inner surface of the tube 5 per hour. When the temperature control using the exhaust temperature sensor 1 is not performed, if the deposits are deposited to a thickness of 10 μm, the process temperature decreases, and the exhaust temperature decreases by about 0.5 ° C. At this time,
When the heat generated from the heater 4 is increased by about 1 ° C., the exhaust gas temperature is increased by about 0.5 ° C. and becomes equal to the temperature before the decrease. Therefore, in the method of the present embodiment, in order to keep the process temperature constant, the temperature measured by the tube temperature sensor 2 when the thickness of the deposit becomes 10 μm is changed from the initial state, for example, from 600 ° C. to about 1 ° C. The operation of the heater 4 is controlled as if it were rising. For this reason, by controlling the rise Δt of the control temperature measured by the tube temperature sensor 2 and cleaning the tube 5 when the rise Δt reaches 2 ° C., the deposited substances such as polycrystalline silicon can be removed. These can be removed before peeling. Thereby, it is possible to prevent the attachment of the attachment to the wafer 10 beforehand. In this case, it is very easy to manage the rise amount Δt.

When a semiconductor device is manufactured using a plurality of semiconductor device manufacturing apparatuses according to the present embodiment, it is necessary to suppress a change in film quality between the devices. However, the amount of deposits deposited differs for each device. For this reason, first, the temperature of each device is made constant by the tube temperature sensor 2 in a state where the deposits are not deposited on the inner surface of the chamber 5. Control is performed so that the temperature of the exhausted gas becomes constant.

The heating device for heating the tube is not limited to the heater. For example, a lamp may be used as a heating device.

[0031]

As described in detail above, according to the present invention,
Since the temperature inside the chamber can be kept constant,
Changes in the crystal grain size in the formed film during the system are suppressed, and the film quality is stabilized. Thus, the yield of the semiconductor device can be improved. In addition, by determining the time to clean the tube based on the amount of temperature increase measured by the tube temperature sensor, the time to clean can be easily known.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a semiconductor device manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a growth time, a control temperature, and a process temperature in a method according to an embodiment of the present invention.

FIG. 3 is a schematic view showing a conventional semiconductor device manufacturing apparatus.

4 is a graph showing a relationship between a growth time, a control temperature, and a process temperature in the conventional semiconductor device manufacturing apparatus shown in FIG.

[Explanation of symbols]

 1; exhaust temperature sensor 2, 21; tube temperature sensor 3, 23; control unit 4, 24; heater 5, 25; tube 6, 26; boat 7, 27; exhaust pipe 8, 28; Mouth 10, 30; Wafer 11, 31; Process gas

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/205 H01L 21/31 H01L 21/308 C23C 16/00 C30B 25/00

Claims (6)

(57) [Claims] In a method of manufacturing a semiconductor device having a step of forming a film on a wafer, the step of forming the film includes the steps of: measuring a temperature of a gas exhausted from a tube into which the wafer is inserted; Controlling the temperature of the tube so that the temperature of the gas is constant. 2. Before the step of measuring the temperature of the gas,
The method according to claim 1, further comprising setting a temperature of the tube to a first temperature at which the wafer is deposited. 3. The step of controlling the temperature of the tube,
Measuring a second temperature of the tube; and cleaning the tube when a difference between the second temperature and the first temperature reaches a predetermined value. The method of manufacturing a semiconductor device according to claim 2. 4. A tube into which a wafer is inserted, a tube temperature sensor for measuring a temperature of the tube, an exhaust temperature sensor for measuring a temperature of a gas exhausted from the tube, a temperature of the tube and a temperature of the gas. An apparatus for manufacturing a semiconductor device, comprising: an in-tube temperature control means for controlling the temperature in the tube based on the temperature. 5. The semiconductor device according to claim 2, wherein said in-tube temperature control means includes a heating device for heating said tube, and a control device for controlling heat generated from said heating device. Manufacturing equipment. 6. The semiconductor device manufacturing apparatus according to claim 3, wherein the control device is connected to the tube temperature sensor and the exhaust gas temperature sensor.