JPS5834399Y2 - heat treatment equipment - Google Patents

Description

[Detailed explanation of the invention] This invention is a MOS field effect transistor (hereinafter referred to as MOSFET).
3) The present invention relates to a heat treatment apparatus for heat-treating highly oxidizing metals in the manufacturing technology of semiconductor devices having transistors (referred to as transistors) as constituent elements.

In manufacturing a MOS transistor, a method of forming source and drain layers in a self-aligned manner using an ion implantation technique using a gate electrode as a mask is well known.

In this case, high temperature heat treatment is required to electrically activate the implanted impurities, and a material that can withstand this high temperature is used for the gate electrode.

Examples include polycrystalline silicon and high melting point metals. In this case, the high melting point metal has the major advantages of a low specific resistance value and excellent microfabriability due to its small particle size.
It is attracting attention because it is expected to improve the electrical characteristics of integrated circuits using transistors.

However, monobuten and tungsten, which are high melting point metals, have strong oxidizing properties and require a heat treatment method or heat treatment device that prevents oxidation of these high melting point metals.

Figure 1 schematically shows a conventional heat treatment apparatus.
2 is a heating element, 2 is a quartz reaction tube having a non-oxidizing gas inlet 4 and the other end is open, 3 is a scavenger, 5 is a sample outlet, and 6 is a sample stage.

If such a heat treatment device is used to heat-treat molybutin, etc. with the metal surface layer exposed, when the sample is pulled out near the sample take-out port after heat treatment, back diffusion of oxygen in the air from the sample take-out port will occur, resulting in damage to the surface of the sample. is oxidized, which adversely affects the electrical properties of the metal surface layer.

In this case, the sample outlet was not left open, and a jig was attached to the quartz reaction tube outlet as shown in Figure 2 17 for the purpose of narrowing the area of the quartz reaction tube outlet and increasing the flow rate of the introduced gas at the outlet. However, back diffusion of oxygen in the air cannot be suppressed.

In order to prevent such oxidation of molybdenum, etc., it is possible to use a heat treatment device with an inert gas sealed inside and take the sample out after cooling it, or heat treat it in a vacuum and take it out after cooling, but consider this from the viewpoint of productivity. It cannot be put to practical use.

On the other hand, Maehara et al.
Although an application has been filed for a heat treatment apparatus, it is not fully satisfactory in the following points.

Figure 3 shows the heat treatment equipment used by Maehara et al. Compared to the conventional heat treatment equipment shown in Figure 1, the quartz reaction tube was extended, a gas inlet 7 was provided in this extension, and the sample stage 6 The quartz reaction tube 2 is characterized in that the tube 8 is provided with a bar 8 having an outer diameter slightly smaller than the inner diameter of the quartz reaction tube 2 attached to both ends in the tube axis direction.

Other symbols in FIG. 3 are the same as in FIG. 1.

In this heat treatment apparatus, when inert gas is introduced from 7, the ridge 8 on the sample outlet side of the sample stage 6 is sufficiently close to the inner diameter side of the quartz reaction tube 2, and there is almost no gap, so the gas blown from 7 is Most of the oxygen flows in the direction of the sample take-out port 5, and back diffusion of oxygen from the sample take-out port 5 can be suppressed.

However, since this heat treatment equipment has a complicated structure for both the quartz reaction tube and sample stage, problems such as damage to the quartz reaction tube or sample stage are likely to occur when cleaning the quartz reaction tube and sample stage. Also, since the outer diameter of the piers provided at both ends of the sample stage in the tube axis direction is slightly smaller than the inner diameter of the quartz reaction tube, when removing the sample stage from the reaction tube, the piers on the upstream side of the gas flow are There are many drawbacks, such as the need to carefully take out the heat treatment equipment so that it does not come into contact with the reaction tube, which can sometimes lead to damage, and the structure of the heat treatment equipment is complex, which naturally increases the cost of maintaining the heat treatment equipment. is also not satisfactory.

Based on the above background, the present invention provides a heat treatment apparatus having a simple structure, which performs heat treatment on a highly oxidizing metal with the surface of the metal exposed.

That is, in the present invention, the outlet of the quartz reaction tube used in the present invention is located at a distance of 80 to 100 cm from the end of the heating element located on the downstream side with respect to the gas flow of the heating element. To provide a heat treatment apparatus characterized in that a quartz reaction tube having a longer overall length is used, and a jig is used to narrow the area of the reaction tube outlet to 4 to 6 cm2. .

The following describes the results of high-temperature heat treatment of a molybdenum thin film using the heat treatment apparatus of the present invention with the surface of the molybdenum thin film exposed.

Fig. 4 shows a schematic diagram of the heat treatment apparatus used. 11 is a heating element, 12 is a quartz reaction tube with a non-oxidizing gas inlet 14 and the other end is open, 13 is a scavenger, and 15 is a sample removal tube. 16 is a sample stage; 17 is a jig (hereinafter referred to as a cap) that narrows the area of the quartz reaction tube outlet 5 to 4 to 6 cm2; It can be attached and detached.

The quartz reaction tube used was such that the reaction tube outlet was located 80 cm from the end of the heating element located on the downstream side with respect to the gas flow of the heating element.

The inner diameter of the quartz reaction tube was 86 mm, and nitrogen gas was supplied at a rate of 500 l/hr.

Therefore, the flow rate of nitrogen gas in the reaction tube at room temperature is 2.4
cm/see.

Set the temperature of the heating element to 1000℃ and place it on the silicon oxide film 3.
Prepare a silicon substrate on which a thin molybdenum film with a thickness of 0.000 A is formed, place it on a sample stand, insert the sample stand near the outlet of the reaction tube, cover the outlet of the reaction tube with a cap, and then place the sample stand in a temperature range of 1000°C. It was inserted and annealed for 20 minutes.

After annealing, as shown in the schematic diagram in Figure 4, the sample stage was pulled out to a position 70 cm upstream from the reaction tube outlet and left there for 10 minutes, and then the sample stage was pulled out to the reaction tube outlet to form a thin molybutin film. I took out the Zinocon board that had been removed.

The molybdenum film annealed in this manner had the same metallic luster as before annealing, and no change in film thickness before and after annealing was observed, except for a change in film thickness due to shrinkage of the molybdenum film due to annealing at 1000°C.

It was also confirmed that the wiring width of the molybdenum wiring processed to a width of 1.5 μm before and after annealing did not change at all within the measurement error.

The sheet resistance values of the cellibutene film before and after annealing are 3.8 g/hole and 0.36 ohm/hole, respectively. Therefore, the specific resistance value is calculated from the sheet resistance value of the molybutene film after annealing at 1000°C for 20 minutes. I X 1O
-5J77cm, which is the same as the result regarding the properties of the molybdenum thin film reported in Applied Physics Vol. What kind of alteration?
It was confirmed that this did not occur.

In the above example, the nitrogen gas flow rate to be introduced is 5001
For example, if you select 30017 o'clock, the sample will be placed at the 4th hour.
When the sample was pulled out to the position shown in the figure, the molybutin film was oxidized and the surface turned brown.

Some experiments have shown that the flow rate of the gas introduced at room temperature within the quartz reaction tube is required to be 2 cm/sec or more.

Furthermore, when a quartz tube was used in which the outlet of the quartz reaction tube was located 40 cm from the downstream end of the heating element with respect to the gas flow, oxidation of the molybutin film occurred even if a cap was used.

In addition, in the above example, when the sample stage was pulled out after annealing in a predetermined temperature range and the sample stage was left at a position 70 cm upstream from the reaction tube outlet for 5 minutes, the sample was pulled out near the reaction tube outlet. Oxidation of the molybdenum film occurs.

Therefore, it is necessary to leave it for at least 10 minutes.

Furthermore, even if the quartz tube used in the above embodiment is used, when annealing is performed without covering the reaction tube outlet with the cap 17,
As expected, oxidation of the molybutin film occurred, confirming the importance of using a cap.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of a conventional heat treatment apparatus, and Figure 2 is a jig used to isolate the outlet of a quartz reaction tube from outside air.
Figure 3 is an improved version of the one shown in Figure 1, JP-A-53-7.
This is a schematic diagram of the heat treatment apparatus shown in Publication No. 9389.
The figure is a schematic diagram of a heat treatment apparatus to which the present invention is applied. The meaning of each symbol is as follows. 1; heating element, 2; quartz reaction tube, 3; scavenger, 4;
Non-oxidizing gas inlet, 5; Sample outlet, 6; Sample stand, 7; Gas inlet, 8; Lighting, 11; Heating element, 1
2: Quartz reaction tube, 13: Scavenger, 14; Non-oxidizing gas inlet, 15; Sample take-out port, 16; Sample stand, 1
7; Cap.

Claims (1)

[Scope of utility model registration request] A cylindrical quartz reaction tube is inserted into the heating element, and the temperature inside the quartz reaction tube inserted into the heating element is set to the desired temperature.
In this heat treatment apparatus that performs heat treatment in a non-oxidizing gas atmosphere introduced into the reaction tube, the quartz reaction tube outlet is 80 to 100 cm measured from the end of the heating element located downstream with respect to the gas flow of the heating element. A heat treatment apparatus characterized in that a quartz reaction tube is used, and a jig is used to narrow the area of the quartz reaction tube outlet to 4 to 6 cm2 at the reaction tube outlet.