JP3068559B2 - Atmospheric pressure chemical vapor deposition equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an atmospheric pressure chemical vapor deposition apparatus, and more particularly to an atmospheric pressure chemical vapor deposition apparatus provided with a powder removing device.

[0002]

2. Description of the Related Art Conventionally, this type of atmospheric pressure chemical vapor deposition apparatus mounts a semiconductor substrate or the like, moves a heated susceptor, ejects a reaction gas from a dispersion head, and deposits a film such as an oxide film on the semiconductor substrate. Had formed. The reaction products and excess unreacted gas generated at this time are exhausted from an exhaust port around the gas ejection port of the dispersion head,
The gas is exhausted from the piping connected to the exhaust port.

[0003] Further, a plurality of exhaust ports, such as one or three, are provided so as to surround the outer periphery of the gas ejection port, for exhausting reaction products and excess unreacted gas. However, if the exhaust air volume of these exhaust ports is not balanced,
The dust remaining on the susceptor will fly up and adhere to the semiconductor substrate, and excess reaction gas will be scattered into the atmosphere. Therefore, as a method of solving this problem, a method of controlling the exhaust amount of the plurality of exhaust ports has been proposed.

For example, in a normal-pressure CVD apparatus disclosed in Japanese Patent Application Laid-Open No. 2-166735, exhaust around a reaction section is performed from a plurality of exhaust ducts, and the static pressure of each is controlled to balance each exhaust amount. Techniques to take are described. But,
According to this conventional technology, when the exhaust duct is blocked due to the accumulation of reaction products, the actual exhaust volume in the reaction section decreases, and when a leak occurs, the apparent exhaust volume increases. There is a new problem that the displacement of the engine is reduced.

FIG. 4 is a piping diagram of an atmospheric pressure chemical vapor deposition apparatus showing an example of the prior art. As shown in FIG. 4, an atmospheric pressure chemical vapor deposition apparatus equipped with a powder removing apparatus for removing the above-described reaction products and capable of controlling the exhaust volume to a constant level is generated from the atmospheric pressure chemical vapor growth apparatus. A powder dust collecting section 20 for removing reaction products to be generated, an orifice pipe section 21 connected to a pipe at a stage subsequent to the powder dust collecting section 20, and a differential pressure gauge 22 for measuring a differential pressure between both ends of the orifice pipe section 21. And a control unit 24 for inputting a signal from the differential pressure gauge 22 and controlling the rotation speed of the exhaust fan 23.

[0006] The atmospheric pressure chemical vapor deposition apparatus removes the exhausted reaction product and excess reaction gas from the powder dust collecting section 20.
, The differential pressure across the orifice tube section 21 is detected, and the control section 24 to which the differential pressure signal has been input calculates and calculates the exhaust flow rate and compares it with a desired exhaust flow rate to determine the rotational speed of the blower 23. It is characterized by controlling and making the exhaust flow rate constant.

[0007]

In the conventional atmospheric pressure chemical vapor deposition apparatus described above, when a reaction product accumulates in the powder dust collecting section 20 and the pressure loss becomes large, the powder in the orifice pipe section becomes large. On the side close to the dust collecting section 20, the concentration of the reaction product increases,
A difference occurs in the gas density between the upstream side and the downstream side of the orifice tube portion 21. There is a problem that an error occurs between the exhaust gas flow rate calculated by the equation described later and the actual exhaust gas flow rate.
For this reason, the gas phase reaction on the semiconductor substrate is not stabilized, and uniformity of film thickness and dopant concentration cannot be obtained. As a result, the dust rises and contaminates the semiconductor substrate.

Accordingly, an object of the present invention is to provide an atmospheric pressure chemical vapor deposition apparatus capable of constantly discharging reaction products and excess unreacted gas at a constant exhaust flow rate.

[0009]

A feature of the present invention is that a first opening is provided so as to surround an outer periphery of a gas blowing portion for injecting a reaction gas, and a first opening is provided so as to surround the outer periphery of the first opening. A dispersion head having a second opening disposed therein, a process gas exhaust pipe connected to the first opening via a first valve and exhausting unreacted gas and reaction products, and the process gas A powder removing device including a powder dust collecting unit connected to a rear end of the exhaust pipe and an air blower connected to a stage subsequent to the powder dust collecting unit; and a second valve via a second valve. An exhaust gas correction pipe connected to the process gas exhaust pipe near the rear end thereof, and a flow meter attached to the exhaust gas correction pipe for measuring an exhaust flow rate, which is attached in the middle of the exhaust pipe; Close the valve and open the second valve The exhaust air is exhausted from the exhaust amount correction pipe by the exhaust fan, the exhaust flow rate is measured by the flow meter, the exhaust flow rate is converted to the exhaust flow rate of the gas containing the unreacted gas and the reaction product, and the regulation of the gas is performed. And a control unit for controlling the number of revolutions of the exhaust fan such that there is no difference between the exhaust gas flow rate and the exhaust gas flow rate.

It is preferable that a third valve, which operates in the same manner as the second valve, is provided in the exhaust gas correction pipe near the connection between the process gas exhaust pipe and the exhaust gas correction pipe. Further, it is desirable to introduce an inert gas into the displacement correction pipe when the first valve is closed and the second valve and the third valve are closed. Then, nitrogen gas is used as the inert gas. Further, it is desirable to have a first static pressure gauge attached to the process gas exhaust pipe. Further, if necessary, a second static pressure gauge attached to the displacement correction pipe is provided.

On the other hand, the measuring mechanism of the flow meter includes an orifice pipe provided in the middle of the displacement correction pipe,
Either a differential pressure gauge for measuring the pressure difference between the front and rear stages of the orifice pipe portion is provided, or an anemometer provided in the middle of the displacement correction pipe is provided.

[0012]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a piping diagram of an atmospheric pressure chemical vapor deposition apparatus according to an embodiment of the present invention.

As shown in FIG. 1, this atmospheric pressure chemical vapor deposition apparatus has a blowing unit 1 for injecting a reaction gas onto a wafer 19.
A process comprising a dispersion head 1 having an opening 1a surrounding the periphery of the opening 0 and further having an opening 1b surrounding the periphery of the opening 1a, and a pipe communicating with the opening 1a of the dispersion head 1. A gas exhaust line 8, an exhaust amount correction line 2 having a pipe communicating with the opening 1b of the dispersion head 1 and connected to the process gas exhaust line 8, and a process gas exhaust line 8;
Dust collecting unit 13 connected through an outlet pipe 7 and an inlet pipe 9 provided near a connection between the air and the displacement correction line 2
And an air blower 14 arranged in the powder dust collecting section 13 through a pipe
And a powder removing device.

A valve 3 and a valve 4 for switching between the process gas exhaust line 8 and the exhaust gas amount correcting line 2 are provided. Furthermore, the displacement correction line 2
An orifice pipe 5 and a differential pressure gauge 6 for measuring a differential pressure between the front and rear sides of the orifice pipe 5 are provided in the middle of the pipe. A control section 15 is provided which receives the differential pressure value signal of the differential pressure gauge 6 and calculates the exhaust flow rate by an equation to be described later, obtains the exhaust flow rate, compares it with a specified exhaust flow rate, and controls the rotation of the blower 14 to correct the difference. ing.

That is, the differential pressure gauge 6 allows the gas phase reaction unit 18 of the atmospheric pressure chemical vapor deposition apparatus to be operated in a state where the process gas is not flowing, such as when the atmospheric pressure chemical vapor deposition apparatus is on standby or when a wafer is transported. That is, by changing the rotation speed of the exhaust fan 14 so that the exhaust gas flow rate at the time becomes a specified amount, the correction is periodically performed so as to be the specified amount. During film formation, the valve 4 is closed, the valve 11 is opened, and, for example, inexpensive nitrogen gas is introduced from the inert introduction line 12 to open
b to prevent reaction products from entering and accumulating in the openings 1b and pipes.

Further, when unreacted gas and reaction products are exhausted in the process gas exhaust line 8, the reaction products are discharged from the connection between the process gas exhaust line 8 and the exhaust gas correction line 2. Into the orifice tube 5
It is desirable to provide a valve 4a at the connection part so as not to contaminate the tub.

As described above, by providing the exhaust gas amount correction line 2, the exhaust gas amount of the process gas exhaust line 8 can be constantly maintained by periodically correcting the exhaust gas amount of the gas phase reaction section 18. A stable gas phase reaction is obtained on the wafer, and the effects of improving the uniformity of the film thickness and dopant concentration formed on the wafer substrate and preventing the adhesion of particles are obtained.

FIG. 2 is a diagram showing a change in the displacement and a difference depending on the presence or absence of correction in a processing sequence for explaining the operation of the atmospheric pressure chemical vapor deposition apparatus of FIG. First, during standby or wafer transfer, which is a preparation stage for starting a gas phase reaction on a wafer, the valves 3 and 11 are closed and the valve 4 is closed.
Is opened, the exhaust gas amount correction line 2 is exhausted by the exhaust fan 14 of the powder removing device.

In this state, the exhaust flow rate is corrected in advance.
For this purpose, first, the differential pressure at the front and rear stages of the orifice pipe section 5 is measured by the differential pressure gauge 6, and the measurement data is sent to the displacement converter which is the calculation section of the control section 15. The conversion is performed by the following equation.

Q: Exhaust flow rate ρ1: Gas density of the orifice plate 5 (on the side of the powder removing device) pn: Gas density of the orifice plate 5 (on the side of the valve 4) hn: Differential pressure between both ends of the orifice plate 5 αn: Orifice Flow coefficient of plate 5 ε: Modification coefficient due to air expansion An: Circular hole area of orifice plate 5 When correction is completed so that the specified exhaust flow rate is obtained, valve 4 is closed, valve 3 is opened, and film formation of wafer 18 is performed. Start. In addition, the valve 11 of the exhaust amount correction line 1 is opened to exhaust the unreacted gas and the reaction product, and the valve 4a is closed to prevent the reaction product from flowing into the exhaust correction line 1.
This is to eliminate pressure loss due to clogging of the opening 1b, the piping, and the orifice tube 5, as described above. Taking this into consideration, ρ1, ρn, αn, ε, and An can always be regarded as constant values.

By storing these values in the storage section of the control section 15 as fixed values obtained in advance by calculation, hn can be calculated from the measurement data obtained by the differential pressure gauge 6 in the equation. The flow rate Q can be calculated. If there is a difference between the exhaust flow rate Q and a specified amount set in advance as a film forming condition, the exhaust fan 1
By changing the number of revolutions of No. 4, the operation is performed so as to eliminate the difference, and the exhaust gas flow rate Q and the specified amount are matched.

Here, the number of rotations of the exhaust fan 14 when the exhaust flow rate Q and the specified amount match is stored. Next, from the start to the end of the film formation, the rotation speed of the exhaust fan 14 is fixed at the above-mentioned stored rotation speed, and then the valve 4 is closed and the valve 3 is opened. The exhaust line is switched to the process gas exhaust line 8.
At the same time, the valve 4a is closed and the valve 11 is opened, and an inert gas is introduced from the inert gas introduction line 12 so that the reaction product during film formation does not flow into the displacement correction line 2. Next, the process gas is blown out from the process gas blow-out unit 10 so that the chemical vapor reaction unit 1
8 is formed and a film is formed.

Next, when the film formation is completed, the valve 3 and the valve 11 are closed, the valve 4 and the valve 4a are opened, and the exhaust amount correction line 2 is exhausted by the exhaust fan 14 of the powder removing apparatus. The differential pressure between the upstream and downstream stages of the orifice tube section 5 is measured by the differential pressure gauge 6, and the exhaust amount Q obtained by sending measurement data to the control section 15 and the film forming conditions stored in advance are set. If there is a difference in the specified amount, the exhaust fan 14 is operated to change the rotation speed so as to eliminate the difference, and the exhaust amount Q matches the specified amount.

As described above, the purpose of the present invention is to correct the exhaust gas flow rate by using the exhaust gas amount correction line 1 at the time of transferring a wafer other than the time of film formation and at the start of operation. It should be noted that an upper limit is provided for the rotation speed of the blower 14, and when the rotation speed reaches the upper limit and the exhaust gas flow rate cannot be corrected to the specified value, a warning signal is generated assuming that the powder dust collection unit 13 is clogged. . Then, the apparatus is stopped, and the powder removing unit 13 is replaced with a new one.

In the above embodiment, the measurement of the exhaust air volume has been described using the orifice tube, but an anemometer may be used instead of the orifice tube. The calculation formula of the exhaust air volume when the anemometer is used is as follows.

FIG. 3 is a piping diagram of a modification of the atmospheric pressure chemical vapor deposition apparatus of FIG. In this atmospheric pressure chemical vapor deposition apparatus, a static pressure gauge 16 is provided in a process gas exhaust line 8 as shown in FIG. The other parts are the same as those in FIG. 1 and are denoted by the same reference numerals.

As the number of times of film formation increases, a reaction product generated by the reaction of the unreacted gas with the atmosphere is not deposited on the wafer 19 as a film or is formed on the inner wall of the pipe of the process gas exhaust line 8. Will stick. In particular, when the opening 1a and the inside of the pipe are closed, there is a concern that the amount of exhaust gas in the gas phase reaction unit 18 decreases even if the number of rotations of the exhaust fan 14 is constant. A similar phenomenon occurs when a leak or the like occurs inside the pipe.

When an abnormality occurs in the piping system as described above, the measurement value of the static pressure gauge 16 provided in the process gas exhaust line 8 fluctuates. The measured value rises as compared with the normal case when the obstruction is obstructed, and decreases when a leak occurs. From these facts, by setting the upper and lower limits with respect to the normal static pressure value in the atmospheric pressure chemical vapor deposition apparatus in advance and constantly monitoring them, it is possible to obtain an effect that abnormal occurrence can be predicted and detected early. Also, in the displacement correction line 2, there is a possibility that reaction products may adhere to the opening 1b.
Is desirably provided.

[0029]

As described above, according to the present invention, apart from the process gas exhaust pipe system for exhausting unreacted gas and reaction products of the process gas, the position of the gas exhaust opening is made substantially the same and the process gas exhaust is performed. A displacement correction piping system connected to the piping connected to the exhaust fan of the piping system, a flow meter that measures the amount of exhaust flowing per unit time through the piping of the displacement correction piping system, a measured value of the flow meter and a prescribed displacement A control unit for controlling the rotation speed of the exhaust fan is provided, and the valve is constantly switched except during film formation, and the exhaust correction pipe system is exhausted by the exhaust fan. By changing the number and correcting the exhaust amount, the exhaust amount of the gas in the switched process gas exhaust piping system can always be kept constant.

Therefore, a stable gas phase reaction on the wafer is obtained, and the effects of improving the uniformity of the film thickness and the dopant concentration formed on the wafer substrate and preventing the adhesion of particles are obtained.

By providing a static pressure gauge in these piping systems as required, it is possible to know at an early stage whether or not there is a leak in the piping and the accumulation of reaction products, so that the apparatus can be operated stably. There is.

[Brief description of the drawings]

FIG. 1 is a piping diagram of an atmospheric pressure chemical vapor deposition apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a change in displacement and a difference depending on the presence or absence of correction in a processing sequence for explaining the operation of the atmospheric pressure chemical vapor deposition apparatus of FIG.

FIG. 3 is a piping diagram of a modification of the atmospheric pressure chemical vapor deposition apparatus of FIG. 1;

FIG. 4 is a piping system diagram of an atmospheric pressure chemical vapor deposition apparatus showing an example of the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dispersion head 1a, 1b opening 2 Displacement correction line 3, 4, 4a, 11 Valve 5, 21 Orifice pipe part 6, 22 Differential pressure gauge 7 Outlet piping 8 Process gas exhaust line 9 Inlet piping 10 Blowout part 12 Inactive Gas introduction line 13,20 Powder dust collecting part 14,23 Exhaust gas 15,24 Control part 16,17 Static pressure gauge 18 Gas phase reaction part 19 Wafer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/31 H01L 21/205 C23C 16/00 C30B 25/00 B01D 45/00 B01D 50/00

Claims (8)

(57) [Claims] A first opening disposed to surround an outer periphery of a gas blowing portion for injecting a reaction gas; and a second opening disposed to surround an outer periphery of the first opening. A dispersing head, a process gas exhaust pipe connected to the first opening via a first valve and exhausting unreacted gas and reaction products, and a powder connected to a rear end of the process gas exhaust pipe. A powder removing device comprising a body dust collecting portion and an air blower connected to a stage subsequent to the powder dust collecting portion; and a process gas exhaust pipe connected to the second opening via a second valve. An exhaust flow correction pipe connected near the rear end of the exhaust pipe, a flow meter attached to the exhaust pipe of the exhaust flow correction pipe to measure an exhaust flow rate,
Close the second valve and open the second valve, exhaust the outside air from the exhaust amount correction pipe with the exhaust fan, measure the exhaust flow rate with the flow meter, and adjust the exhaust flow rate of the gas containing the unreacted gas and the reaction product. A normal pressure, comprising: a control unit that converts the exhaust flow rate and controls the number of revolutions of the blower so that a difference between the exhaust flow rate of the gas and the specified exhaust flow rate of the gas is eliminated. Chemical vapor deposition equipment. 2. The exhaust gas correction pipe near the connection between the process gas exhaust pipe and the exhaust gas correction pipe has a second shape.
2. The atmospheric pressure chemical vapor deposition apparatus according to claim 1, further comprising a third valve that operates in the same manner as the first valve. 3. An inert gas is introduced into the displacement correction pipe when the first valve is closed and the second valve and the third valve are closed. Atmospheric pressure chemical vapor deposition apparatus as described. 4. The atmospheric pressure chemical growth apparatus according to claim 3, wherein said inert gas is nitrogen gas. 5. The atmospheric pressure chemical vapor deposition apparatus according to claim 1, further comprising a first static pressure gauge attached to the process gas exhaust pipe. 6. A normal pressure chemical vapor phase according to claim 1, further comprising a second static pressure gauge attached to said displacement correction pipe. Growth equipment. 7. A measurement mechanism of the flow meter, comprising: an orifice pipe provided in the middle of the displacement correction pipe; and a differential pressure gauge for measuring a pressure difference between a former stage and a latter stage of the orifice tube. An atmospheric pressure chemical vapor deposition apparatus according to any one of claims 1, 2, 3, 5, and 6. 8. The flow rate meter according to claim 1, wherein the measurement mechanism of the flow meter includes an anemometer provided in the middle of the displacement correction pipe. Item 7. An atmospheric pressure chemical vapor deposition apparatus according to any one of Items 6.