JPH04144226A - Semiconductor manufacturing equipment and control method thereof - Google Patents

Abstract

PURPOSE:To facilitate temperature control, reduce contamination, and stably supply water vapor, by specifying the ratio of the maximum sectional area to the minimum sectional area of a vessel in the horizontal direction. CONSTITUTION:When the maximum sectional area of a vessel 2 in the horizontal direction is M and the minimum sectional area is S, M/S is set smaller than 8, because the supply amount of water vapor is apt to be influenced by the liquid surface area in the vessel 2. That is, the flow rate of the water vapor supplied to a vacuum chamber 8 from the water vapor generating vessel 2 depends on the area of the water surface, when the conductance of a pipe 10 connecting the vessel 2 and the chamber 8 is assumed to be constant. As a result, when the maximum area of the water surface is M and the minimum area is S, the ashing rate which is always constant can be obtained in the case of M/S<8.

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] This invention relates to an apparatus for supplying water vapor to a vacuum chamber that performs processes such as ashing of photoresist, and a method for controlling the same.

The purpose of the present invention is to provide a device and a method for controlling the same that can easily control temperature, cause little pollution, and stably supply water vapor.

l) A processing device that performs processing by introducing water vapor evaporated in a container containing water into a vacuum chamber.

When the maximum horizontal cross-sectional area of the container is M and the minimum cross-sectional area is S, the container is configured so that M/S<8 holds true.

2) The container has an inner surface coated with a resin, is immersed in a temperature-controlled liquid, and has a steam supply port above the water surface.

3) When water vapor evaporated in a container containing water is introduced into a vacuum chamber through a mass flow controller for processing, the flow rate range of the water vapor controlled by the mass flow controller is set to the water vapor in the water vapor supply system of the processing equipment. It is configured to be 50 to 100% of the maximum flow rate of water vapor determined by pressure.

4) The water temperature in the container is adjusted so that the maximum flow rate of water vapor determined from the vapor pressure of water in the water vapor supply system is smaller than the maximum flow rate that can be controlled by the mass flow controller.

[Industrial application field]

The present invention relates to a semiconductor manufacturing device and a control method thereof, and more particularly to a device for supplying water vapor to a vacuum chamber for processing such as photoresist ashing, and a control method thereof.

In recent years, gas-phase processing, which uses plasma or the like to treat the surface of materials in a vacuum or at reduced pressure, has come to be used in various fields such as semiconductor devices, liquid crystals, polymer materials, and ceramics due to its good controllability. It's coming.

However, suitable gases for use in processing do not necessarily have high vapor pressures; in particular, water vapor has a low vapor pressure of about 20 Torr at room temperature, and its vapor pressure varies greatly depending on temperature, so it is difficult to control large quantities. It is one of the gases that is difficult to flow well.

Particularly in the manufacture of semiconductor devices, water vapor is used as one of the reactive gases for ashing resist and other resin films, and an apparatus that can stably supply water vapor is required to improve processing accuracy.

The present invention can be used as a device and a control method that meet this demand.

[Conventional technology]

Conventionally, quartz was often used for water vapor generation containers containing water for introducing water vapor into vacuum chambers, but 9 quartz is easily damaged and has poor heat conduction, resulting in temperature unevenness. The disadvantage was that it was difficult to control the amount. In addition, enameled soda glass was often used for the inner wall of metal containers, but impurities (Na, Fe,
, Ca, etc.) dissolved in the water and became a source of pollution.

In addition, the method of supplying water vapor is based on the saturated vapor pressure of water vapor (25
It is characterized in that it is supplied by the difference between the internal pressure of the chamber (approximately 24 Torr at °C) and the internal pressure of the chamber.

Therefore, in order to keep the supply amount of steam constant, it is necessary to keep the temperature of the steam generating container constant.

Conventionally, temperature control using a mantle heater was used, but its performance was limited and was not sufficient.

Additionally, water vapor has traditionally been one of the most hated gases to be introduced into a vacuum chamber, as it can degrade the pump oil of rotary pumps, etc., or remain in the vacuum chamber, impairing the degree of vacuum achieved. Therefore, the method of actively introducing water vapor into the vacuum chamber has not been seriously considered.

When performing vapor phase processing by actively introducing water vapor, generally the carrier gas is bubbled through water and introduced into the vacuum chamber together with the carrier gas, as shown in Figure 5. Ta.

FIG. 5 is a configuration diagram illustrating the supply of water vapor according to a conventional example.

-, 41 is a bubbler containing water, 42 is a vacuum chamber for performing gas phase processing, 43 is a mass flow controller (MFC), and 44 is a valve.

The carrier gas is introduced into the water in the bubbler 41 by turning the mass flow controller 43, and the water vapor is introduced into the vacuum chamber 42 together with the carrier gas.

In this method, the amount of water vapor that can actually be introduced is only the partial pressure of water vapor in the mixture of carrier gas and water vapor.

Since the vapor pressure of the carrier gas is usually higher than that of water vapor, the amount of water vapor contained in the gas mixture is not so large.

Therefore, when it is desired to introduce a large amount of water vapor, a larger amount of carrier gas must be flowed, and large-scale exhaust equipment is required to maintain the vacuum in the vacuum chamber.

Moreover, with this method, the range in which the flow rate ratio of carrier gas and water vapor can be changed is narrow.

[Problem to be solved by the invention]

Therefore, with conventional devices, there is a lot of contamination, and it is difficult to stably control the flow rate of water vapor.

Additionally, it was difficult to control the flow rate of water vapor supplied to the vacuum chamber.

It is an object of the present invention to provide an apparatus and a control method thereof that can easily control temperature, cause less contamination, and stably supply water vapor.

[Means to solve the problem]

What is the solution to the above problem?

(2) A processing device that performs processing by introducing water vapor evaporated in a container containing water into a vacuum chamber.

A semiconductor manufacturing apparatus characterized in that M/S<8 holds true, where M is the maximum cross-sectional area of the container in the horizontal direction and S is the minimum cross-sectional area of the container, or 2) the container has an inner surface coated with a resin. The semiconductor manufacturing apparatus described in l) above, which is immersed in a temperature-controlled liquid and has a water vapor supply port above the water surface; When the water vapor is introduced through a mass flow controller to perform processing, the flow rate range of water vapor controlled by the mass flow controller is 50 to 100% of the maximum flow rate of water vapor determined from the vapor pressure of water in the water vapor supply system of the processing equipment. or 4) controlling the water temperature in the container such that the maximum flow rate of steam determined from the vapor pressure of water in the steam supply system is smaller than the maximum flow rate that can be controlled by the mass flow controller. This is achieved by the method for controlling a semiconductor manufacturing apparatus described in 3) above.

[Effect]

(1) Steam supply device The present invention makes it possible to efficiently control the temperature by using a material with good heat conductivity such as an aluminum alloy for the steam generation container containing water, and furthermore, by processing the inner surface of the container with resin, heat conduction is achieved. This prevents contamination by impurities from the container without impairing its properties.

In addition, the present invention maintains the sealed steam generating container connected to the vacuum chamber through a pipe at a constant temperature using a constant temperature water heater, making it possible to control the temperature inside the container uniformly and with excellent thermal efficiency. This enables a stable supply of water vapor.

Furthermore, in the present invention, since the amount of water vapor supplied is easily affected by the liquid surface area in the container, taking this fact into account, if the maximum horizontal cross-sectional area of the container is M and the minimum cross-sectional area is S, then M /S
This is based on the experimental result that stable supply of water vapor is possible by setting <8.

In fact, in downstream ashing of a mixed gas of oxygen and water vapor, when a container with M/S<8 was used, water vapor could be supplied at a stable flow rate and a stable ashing rate was obtained (as in the example). (See explanation in Figure 2)
.

In addition, by keeping the water surface at least 1 cm away from the gas supply port of the steam generation container during use, even if deaeration occurs within the steam generation container, moisture will not enter the supply port.

(2) Method of controlling the water vapor flow rate When introducing water vapor into the vacuum chamber from the sealed water vapor generation container shown in Figure 3 through the mass flow controller, the maximum flow rate is determined by the conductance of the water vapor supply system and the water temperature in the water vapor generation container. (However, since water vapor does not liquefy inside the pipe, the temperature must be higher than the water temperature.)

For example, if the water temperature is 50°C, the maximum flow rate is 5003°C.
CM, a mass flow controller with an allowable flow rate larger than 5003CCM will have a flow rate of approximately 0 to 500300CCM.
In the range of M, a mass flow controller with an allowable flow rate smaller than 5003 CCM should be able to control the flow rate within the range of approximately θ to the maximum allowable flow rate of the mass flow controller.

However, when the mass flow controller restricts the flow rate to a small amount, the water vapor liquefies and clogs the mass flow controller. This is thought to be because a pressure difference is created between the upstream and downstream sides of the mass flow controller, and when the water vapor passes through the orifice of the mass flow controller, it is cooled and liquefied by adiabatic cooling. Therefore, the flow rate range that can actually be controlled is regulated by the vapor pressure of water vapor in the supply system.

As explained in the example below, if the flow rate range of water vapor controlled by the mass flow controller is 50 to 100% of the maximum flow rate of water vapor determined from the vapor pressure of the water vapor in the water vapor supply system introduced into the vacuum chamber, the mass flow controller may become clogged. was found not to occur.

〔Example〕

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention.

This example corresponds to M/S=1.

In the figure, the steam generating container 2 and its upper lid 3 are made of aluminum alloy, and the inner surface is coated with thick Teflon to prevent the aluminum alloy from being exposed and to prevent pinholes from forming.

Further, the steam generating container 2 is provided with a viewing window 6 made of transparent quartz for liquid level detection, and is sealed with a gasket 7 made of impurity-free rubber.

Further, the space between the main body 9 and the steam generating container 2 becomes a hot water tank, and the temperature of the hot water is controlled by a chiller.

Hot water is circulated through the inlet and outlet.

The inside of the steam generating container 2 is evacuated and filled with steam during use.

The steam generating tank 2 has good thermal conductivity and good temperature control, and it is extremely easy to maintain it at a predetermined temperature.

Fill the steam generation container 2 with pure water and maintain it at 50°C.
The results of analysis of impurities before and after leaving the sample for 0 days are shown in the table below.

Type of impurity Na Fe Ca Initial amount (mgN) 0.05 0.01 0.1
2 Final amount Cmg/l) 0.16 ≦0.01
≦0,02 From this table, it can be seen that the change in the amount of impurities is small.

At this time, measurements were conducted under the same conditions for a case where the steam generating container 2 was made of aluminum and was not coated with Teflon as Comparative Example 1, but the impurities increased by two orders of magnitude or more when left standing.

In addition, as Comparative Example 2, measurements were conducted under the same conditions in a case where the steam generating container 2 was made of enameled soda glass, but Fe and Ca were found to be several mg/l after being left alone! , Na increased to several tens of mg/i.

FIG. 2 is a characteristic diagram of downstream ashing using oxygen and water vapor.

The vacuum chamber that performs the ashing process contains water vapor (H2O
) and oxygen (0□) are introduced through separate routes.

Looking at the HzO/(02+HtO)% dependence of the ashing rate, in order to obtain the maximum value of the ashing rate.

It can be seen that it is necessary to supply water vapor so that H20/(0,+H,O) is a flow rate ratio determined between 10 and 80%.

The flow rate of water vapor supplied from the water vapor generating container to the vacuum chamber depends on the area of the water surface, assuming that the conductance of the pipe connecting the two is constant. Therefore, it becomes necessary to determine the permissible range of changes in the area of the water surface. Therefore, the area of the water surface is maximum M.

When the minimum S was set, the same ashing rate could always be obtained when M/S<8.

The experiment was conducted using a conical container with an upper area of s = i and a lower area of M = 8. At this time, the area of the water surface was S
While changing from to M, the ashing rate is 0.28 to 0.
．． A substantially constant value of 30 μm/min was obtained. On the other hand, if a container with M larger than 8 is used, the ashing rate becomes unstable.

FIG. 3 is a configuration diagram of the apparatus in which the mass 70-controller flow rate control experiment was conducted.

In the figure, mass flow controller (MFC) 11
Estech 5EC-340O3 was used. 12 is a heater.

13 is a temperature control device.

FIG. 4 is a diagram showing the relationship between the maximum flow rate and the water temperature in the apparatus of FIG. 3.

At this time, the mass flow controller is fully open.

Now, let's set the water temperature to 65°C and use a mass flow controller to reduce the flow rate by 50 SCCM every 10 minutes.

When setting the 3003CCM, the mass flow controller became clogged and steam stopped flowing after about 5 minutes.

When the water temperature was 50°C, the mass flow controller was clogged at 1003CCM.

Almost the same results were obtained even when the mass flow controller was replaced with another one.

Next, an example in which the water vapor supply system of the embodiment is used in a souring device will be described.

After connecting the water vapor supply system shown in Figure 3 to the vacuum chamber of the ashing device and mixing oxygen with water vapor in the vacuum chamber, 2.45 GHz microwave power was applied to generate plasma in the vacuum chamber. occurred.

At this time, the water temperature is 60°C9 the flow rate of water vapor is 11003
CC, the flow rate of oxygen was 9005 CCM.

Gas is supplied, 10 seconds later, plasma is turned on to start ashing, 1 minute later, plasma is turned off, water vapor is immediately switched to bypass, and 1 minute later, water vapor is allowed to flow into the vacuum chamber again.

By repeating this series of operations, we conducted a water vapor supply test under actual equipment operating conditions.

Approximately 20 seconds after turning on the plasma for the third time, the color of the plasma changed from pink to blue, indicating that no water vapor was flowing.Therefore, after removing the blockage in the mass flow controller, the water temperature was raised to 50℃. It was lowered and plasma treatment was performed again.

The luck was: 155th time - Mass 70 controller was clogged, and when I raised the water temperature to 48°C, the mass flow controller was not clogged (I was able to perform plasma treatment 50 times).

Similarly, 200 SCCM, 300 SCCM
An experiment was conducted to determine the maximum water temperature for a stable flow of water vapor, and the results were 58°C and 165°C, respectively.

That is, it was found that the mass flow controller was clogged when the flow rate was less than about half of the maximum flow rate for each water temperature.

Furthermore, each of the above embodiments has the following features.

■ The inner walls of the piping that introduces water vapor into the vacuum chamber are also coated with Teflon to prevent contamination and facilitate heat retention.

■ When there is no need to supply water vapor to the vacuum chamber, a bypass is provided that allows the water vapor to flow directly to the vacuum pump without passing through the vacuum chamber.

Further, an example of a processing apparatus according to the present invention is as follows.

■ A plasma processing device that processes gas containing at least water vapor by turning it into plasma.

■ Plasma downstream processing equipment that separates the plasma and the object to be processed.

■ Plasma downstream processing equipment that performs processing by introducing a gas containing at least water vapor downstream of the plasma.

(2) The plasma downstream processing device described above is an ashing device that incinerates organic matter.

〔Effect of the invention〕

As explained above, according to the present invention, temperature control is easy and water vapor can be supplied at a stable flow rate with less contamination by impurities.

As a result, a stable ashing rate can be obtained.

It is now possible to contribute to improving the accuracy of wafer processing.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an apparatus according to an embodiment of the present invention. Figure 2 shows the characteristics of downstream ashing using oxygen and water vapor. FIG. 3 is a configuration diagram of the apparatus in which the mass flow controller flow rate control experiment was conducted. FIG. 4 is a diagram showing the relationship between maximum flow rate and water temperature in the apparatus of FIG. 3. FIG. 5 is a configuration diagram illustrating the supply of water vapor according to a conventional example. In fig. ■ is the main body. 2 is a steam generating container. 3 is the top lid. 4.5.7 is Patsukin. 6 is a peephole. 8 is a vacuum chamber. 9 is a valve. lO is piping. 11 is the mass flow controller (MFC)
Isakukuni +00 Steam's Etenma, t (SCCM) Water vapor's tjC tree U's Sekiiousen diagram against the failure of Figure 3

Claims (1)

[Claims] 1) A processing device that processes water vapor evaporated in a container containing water by introducing it into a vacuum chamber, wherein the maximum horizontal cross-sectional area of the container is M, and the minimum cross-sectional area is M. When S, M
A semiconductor manufacturing apparatus characterized in that /S<8 holds true. 2) The semiconductor manufacturing apparatus according to claim 1, wherein the container has an inner surface coated with a resin and is immersed in a temperature-controlled liquid, and a steam supply port is provided above the water surface. 3) When processing water vapor evaporated in a container containing water by introducing it into a vacuum chamber through a mass flow controller, the flow rate range of the water vapor controlled by the mass flow controller should be adjusted to match the water vapor in the water vapor supply system of the processing equipment. A method for controlling semiconductor manufacturing equipment, characterized in that the flow rate is 50 to 100% of the maximum flow rate of water vapor determined by pressure. 4) The water temperature in the container is adjusted so that the maximum flow rate of water vapor determined from the vapor pressure of water in the water vapor supply system is smaller than the maximum controllable flow rate of the mass flow controller. A method for controlling semiconductor manufacturing equipment.