JPS62115711A - Processing device - Google Patents

Abstract

PURPOSE:To enable fluid concentration in a processing space to be exactly maintained at a fixed value, by controlling a flow rate of the fluid supplied inside the processing space on the basis of the detection concentration of the processing fluid inside the processing space. CONSTITUTION:When a door 8 mounted on furnace unit 3 is opened so that a wafer 2-arranged jig 6 is inserted into processing space 5 from a furnace inlet 7 to be placed on a prescribed position, the processing space 5 is heated to a fixed temperature condition. Then, nitrogen 12 and oxygen 13 are supplied as processing gases into the processing space 5 through respectively fluid-supply tubes 14a and 14b, to start a diffusion process in which impurities are diffused on a prescribed surface portion of the wafer 2. During the diffusion process, concentration of oxygen in the processing space 5 is detected by sensor 9a and 9b located in the processing space 5, to send the detected information to a control part 10. Valve mechanism of a mass-flow-controller 14b for oxygen 13 is operated at the control part 10 on the basis of the detected information. Thus, the amount of the oxygen 13 supplied into the processing space 5 can be controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field C] The present invention relates to a processing technology, particularly to a technology that is effective when applied to a diffusion process for diffusing impurities onto the surface of a wafer in the manufacture of semiconductor devices.

[Background Art] In the manufacturing process of semiconductor devices, for example, a nitrogen atmosphere is introduced into the furnace to diffuse impurities onto the surface of a semiconductor device manufacturing wafer (hereinafter referred to as "wafer J") made of silicon or the like. A so-called diffusion bag Ffl in which a wafer is placed and processed is known.

By the way, in the above technique, the silicon surface may be etched due to the supply of nitrogen, or the surface of the wafer may be roughened, so a minute amount of oxygen is supplied together with nitrogen to form a minute oxide film on the surface of the wafer. It is conceivable to perform treatment while growing.

In this case, the amount of oxygen supplied into the furnace body can be extremely small compared to nitrogen, but if the flow rate cannot be controlled accurately, it will cause variations in the oxide film, which will directly affect variations in product characteristics. Become. Therefore, it is necessary to accurately control the amount of oxygen in the furnace, even if it is a minute amount.In this regard, a flow rate control mechanism such as a so-called mass flow controller is installed to control the amount of oxygen supplied into the furnace. It is possible that

However, due to the precipitation of oxygen from the walls of the furnace body made of quartz tubes, or the entrainment of outside air into the furnace body, even if the flow rate of oxygen to be supplied is precisely controlled, it is difficult to accurately control the amount of oxygen inside the furnace body. The inventors have found that it is difficult to control the

Furthermore, not only in the micro-oxidation process mentioned above, but also when using other processing gases, it is difficult to accurately control the fluid concentration inside the furnace body by controlling the supply flow rate externally. was revealed by the present inventor.

An example of a detailed description of the diffusion device technology is given in "Electronic Materials November 1984 Special Edition, VLSI Manufacturing and Testing Equipment Guidebook," published by Kogyo Kenkyukai Co., Ltd., November 20, 1984, p. 57. There is ~P61.

[Object of the Invention] An object of the present invention is to provide a technique that can accurately maintain the concentration of a processing fluid within a processing space.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Summary of the Invention] A brief overview of typical inventions disclosed in this application is as follows.

That is, by adopting a processing device structure having a fluid concentration detection mechanism provided in a processing space, and a flow rate control means that controls the flow rate of the processing fluid into the processing space in conjunction with the fluid concentration detection mechanism. Since the flow rate of the processing fluid supplied into the processing space can be controlled based on the detected concentration of the processing fluid within the processing space, the fluid 4 degree within the processing space can be accurately maintained at a predetermined value. It becomes possible.

[Example] FIG. 1 is a schematic cross-sectional view showing a processing apparatus that is an example of the present invention.

The processing apparatus 1 of this embodiment is a diffusion apparatus that diffuses impurities into a predetermined portion of the surface of a wafer 2 as a processing object.
It can also be used as an oxidation device for forming an oxide film.

The processing apparatus 1 has a furnace body 3 formed of, for example, quartz glass into a substantially cylindrical shape and placed horizontally, and this furnace body 3 is arranged so as to surround the furnace body 3 from the sides in the length direction. The interior, that is, the processing space 5 is heated by the attached heater 4.

A furnace lower is provided at one end of the furnace body 3 for loading and unloading a plurality of wafers 2 on a boat-shaped jig 6 in parallel directions, and this furnace lower can be opened and closed by a door 8. It has a flexible structure.

In addition, sensors 9a and 9b for detecting oxygen concentration are installed at two locations in the processing space 5, and detect the oxygen concentration in the processing space 5 and transmit the detected information to a control unit IO provided outside. It is supposed to be done.

On the other hand, the other end side of the furnace body 3 has a curved constricted part 3a, and two fluid supply pipes 11a are connected from the tip of the constricted part 3a.
and llb are introduced into the processing space 5 from the outside. In this embodiment, one fluid supply pipe 11a is for supplying nitrogen 12, and the other fluid supply pipe 11b is for supplying oxygen 13.
Mass flow controllers 14a and 14b, which are flow rate control mechanisms, are interposed in intermediate portions of a and ttb, respectively. These mass flow controllers 14a, 14b
Although the structure is not shown, it has a valve mechanism that controls the flow rate of fluid, and this valve mechanism is equipped with an actuator with a ball valve made of sapphire or the like attached to its tip, and a ball valve buried inside. The flow rate is controlled by the positional relationship between the ball valve, which is displaced by the heating of the heater, and the outlet. In this embodiment, the operation of the valve mechanism of the mass flow controller 14b on the fluid 4RU pipe 1 lb side of the oxygen 13 is controlled by the control unit 10.

Next, the operation of this embodiment will be explained.

When the door 8 attached to the furnace body 3 is opened and the jig 6 with the wafers 2 aligned is inserted into the processing space 5 from the furnace lower and placed at a predetermined position, the processing space 5 is heated by the heater 4. It is heated until a predetermined temperature condition is reached.

Next, nitrogen 12 and oxygen 13 as processing gases are supplied into the processing space 5 from the respective fluid supply pipes 14a and 14b, and a diffusion process for diffusing impurities to a predetermined portion of the surface of the wafer 2 is started.

During this diffusion step, the oxygen concentration within the processing space 5 is detected by sensors 9 a and 9 b installed within the processing space 5 , and this detection information is sent to the control section 10 . The control unit 10 operates the valve mechanism of the mass flow controller 1.4b for the oxygen 13 based on the detected information. This results in oxygen 1
3 into the processing space 5 is controlled.

The above control is effective, for example, in the following cases. That is, during the diffusion process, phenomena such as precipitation of oxygen from the inner surface of the furnace body 3 or entrainment of oxygen due to the intrusion of outside air from the installation of the door 8 occur in the processing space 5, and the flow of oxygen from the fluid supply pipe 11b occurs. When the oxygen concentration in the space 5 has increased compared to the oxygen supply amount of 10 sends a control signal to the mass flow controller 14b to suppress the amount of oxygen 13 passing through the fluid supply pipe 11b.

Conversely, if the oxygen concentration in the processing space 5 becomes lower than a preset reference value for some reason, a control signal from the control unit 10 causes the mass flow controller 14 to
The valve mechanism b is actuated to increase the amount of oxygen 13 supplied.

In this way, since the oxygen concentration in the processing space 5 is directly detected and the flow rate of the oxygen 13 is controlled based on this detection information G, the oxygen concentration in the processing space 5 can always be maintained at a predetermined value. Stable processing can be achieved.

In addition to the above-described diffusion device, the processing device 1 having the structure described in “2” also includes oxidized W used for forming an oxide film on the wafer 2.
Since it can also be used as 2, the purpose may be changed from an oxidation device to a diffusion device, but even in this case, it has the following usefulness.

That is, when this processing apparatus 1 is used as an oxidation apparatus using only oxygen as the processing gas and then used as an apparatus for expansion 11 using nitrogen and a small amount of oxygen, the residual from the oxidation process is removed from the inner wall surface of the furnace body 3. There is a risk that oxygen will precipitate and the inside of the processing space 5 will be in an excessive oxygen state, but according to this embodiment, as explained above, the oxygen concentration inside the processing space 5 is detected and the oxygen supply flow Since it is controlled, stable processing can be performed. Therefore, even when the purpose of the processing device is changed, stable processing can be achieved immediately after the change.

[Effect (1), a fluid concentration detection mechanism provided in the processing space,
By adopting a processing device structure having a flow rate control means that controls the flow rate of the processing fluid into the processing space in conjunction with the fluid concentration detection mechanism, the processing fluid can be controlled in the processing space based on the detected concentration of the processing fluid in the processing space. Processing fluid flow supplied within ■
Since the fluid 4 in the processing space can be controlled
It becomes possible to accurately maintain the temperature at a predetermined value.

(2) According to [1] above, in the diffusion process using nitrogen and a minute amount of oxygen, the amount of oxygen in the processing space can be maintained at a predetermined value, so it is possible to realize a stable diffusion process. can.

(3) According to (1) above, even if the processing fluid is changed, the concentration of the processing fluid in the processing space can be controlled immediately after the change, making it extremely easy to change the use of the processing device. I can do it.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, although the concentration detection and meteor control are performed only for oxygen in the embodiment, they may also be performed for nitrogen.

Furthermore, although the concentration detection mechanism has been described in the case where two sensors are installed, a single sensor or three or more sensors may be installed. Furthermore, regarding the method of installing the sensor, it is also possible to form a drawer tube in the quartz tube and attach the sensor inside the drawer tube.

[Field of Application] In the above description, the invention made by the present inventor was mainly applied to a diffusion device using a mixed fluid of nitrogen and a small amount of oxygen, which is the field of application of the invention, but the present invention is not limited to this. However, it is an effective technique that can be applied to processing equipment that uses other fluids.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing a processing apparatus which is an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Processing device, 2... Wafer, 3... Furnace body, 3
a... Aperture section, 4... Heater, 5... Processing space,
6... Jig, 7... Hearth, 8... Door, 9a, 9
b...Sensor, lO...Control unit, 11a, 11b.
...Fluid supply pipe, 12...Nitrogen, 13...Oxygen, 1
4a, 14b...Mass flow controller. one'~,

Claims (1)

[Scope of Claims] 1. A processing apparatus comprising a processing space into which a processing fluid is supplied with an object to be processed positioned therein, comprising: a fluid concentration detection mechanism provided within the processing space; A processing apparatus comprising: a flow rate control means for controlling the flow rate of the processing fluid into a processing space in conjunction with the fluid concentration detection mechanism. 2. The processing apparatus according to claim 1, wherein the processing fluids supplied to the processing space are nitrogen and oxygen, and the processing apparatus has at least a concentration detection mechanism for oxygen and a flow rate control means linked thereto. . 3. The processing apparatus according to claim 1 or 2, wherein the flow rate control means is a mass flow controller valve. 4. The processing apparatus according to claim 1 or 2, wherein the object to be processed is a wafer for manufacturing a semiconductor device.