JPS61263125A - Dry etching apparatus - Google Patents

Abstract

PURPOSE:To etch uniformly a large number of workpieces, by supplying an etching gas of high concentration to a reaction vessel intermittently, and by applying a high-output microwave to said etching gas synchronously with the timing of introduction. CONSTITUTION:A mixed gas of CF4 and O2 from a gas source is introduced into a gas vessel 2 through a flow control valve 1 and accumulated therein in the state of high pressure. A solenoid valve 3 puts a gas flow channel in an opened state in synchronization with a pulse signal from a pulse controller 22, and the mixed gas accumulated in the gas vessel 2 is supplied as a gas pulse of high pressure to a plasma generator 4. Since a microwave power source 6 outputs a microwave synchronously with the pulse signal, the gas pulse is turned into plasma by the irradiation of the high-output microwave from a waveguide 7, and it is introduced as an active gas of high concentration into a reaction vessel 9. The active gas introduced into the reaction vessel 9 is dispersed and straightened by a dispersion plate 11 and a straightening plate 13 and then is supplied for etching of each wafer 18.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a dry etching apparatus, and more particularly to a dry etching apparatus capable of uniformly etching a plurality of objects to be processed.

[Technical background of the invention and its problems]

Microwave discharge type chemical dry etching (CDE) apparatuses have been known for some time. A CDE device activates a reactive gas by irradiating it with microwaves from a plasma generator, and then introduces the resulting active gas into a reaction container, and the etching chamber and plasma chamber are separated. Therefore, it has the advantage that damage to the wafer due to plasma is small.

Incidentally, in conventional CDE apparatuses, etching gas is continuously supplied into the reaction vessel, and reaction products produced by etching are continuously exhausted.

However, in recent years, in order to meet the demand for improved production efficiency, the number of objects to be processed in one etching process has increased, and the size of the objects to be processed has become larger. This led to the following problems.

That is, when processing a large number of wafers, the space in which the wafers are placed becomes larger, making it difficult to make the concentration of the etching gas supplied into the reaction vessel uniform over the entire space in which the wafers are placed. For this reason, there is a problem in that the etching rate varies depending on the location where the wafer is installed. One of the causes of such spatial non-uniformity in gas concentration is the behavior of reaction products under vacuum. In other words, during etching, an active gas is introduced into the reaction vessel and at the same time the reaction products generated by etching are exhausted, but under vacuum, the reaction products are not completely exhausted and the reaction products are removed from the reaction vessel. It may be attached to the wall. It is conceivable that such adhered gas is mixed into the active gas due to changes in the air flow within the reaction vessel, partially reducing the gas concentration.

[Object of the Invention] The present invention was made based on the above problem, and its object is to provide a dry etching apparatus that can uniformly etch a large number of objects to be processed.

[Summary of the Invention] The present invention is characterized by using a batch processing method instead of the conventional continuous processing method.

That is, the present invention includes a reaction container that accommodates the object to be processed;
In a dry etching apparatus in which a plasma generator for activating the etching gas is interposed in a gas flow path between the etching gas supply source and the etching gas supply source that supplies the etching gas to the reaction vessel, the etching gas supply source is A concentrated etching gas is intermittently supplied to the reaction vessel, and the plasma generator irradiates the high concentration etching gas with high-power microwaves in synchronization with the introduction timing of the high concentration etching gas. It is characterized by certain things.

The high concentration etching gas is preferably 10 to 100 times more concentrated than the gas used in the conventional continuous operation method, and the microwave output is also preferably 10 to 100 times the conventional one.

〔Effect of the invention〕

According to the present invention, since a highly concentrated etching gas is intermittently introduced into the reaction vessel, the etching rate is determined not by the flow rate of the etching gas but by the reaction rate between the etching gas and the object to be processed. It becomes dependent.

Therefore, in this case, all the objects to be processed will be etched at a uniform rate determined by the reaction rate, even if there is some spatial variation in concentration.

Furthermore, since a highly concentrated etching gas is used in this case, the reaction rate is extremely fast, and a delay in the reaction rate due to not continuously supplying the gas can be sufficiently absorbed.

Moreover, since the present invention stops the gas supply and microwave irradiation for a predetermined period, the overall etching gas consumption and power consumption do not increase.

Incidentally, reaction products that do not contribute to the reaction can be sufficiently discharged when the etching gas is not supplied by selecting an appropriate duty of the operation pulse.

(Embodiment of the Invention) Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a CDE device according to this embodiment. That is, a gas source (not shown) is connected to the introduction side of the gas container 2 via the flow rate regulating valve 1. The gas container 2 stores a certain amount of mixed gas. The discharge side of this gas container 2 is connected to a plasma generator 4 via a solenoid valve 3. And the above gas source, flow m! ! An etching gas supply source is constituted by the regulating valve 1, the gas container 2, and the electromagnetic valve 3.

The plasma generator 4 includes a discharge tube 5 made of a quartz tube that guides the mixed gas supplied from the gas container 2 into the inside, and a microwave power source 6 with a frequency of, for example, 2.45 GHz and an output of 20 kW.
It is comprised of a waveguide 7 that transmits the microwave output from the microwave power source 6 to the discharge tube 5. This plasma generator 4 is connected to a reaction vessel 9 via a plasma transport pipe 8.

The reaction vessel 9 is made entirely of AQ, for example, and includes a dispersion plate 11.12 that disperses the introduced gas near the gas inlet and outlet, and a rectifier plate 13.14 that rectifies the dispersed gas. is arranged. A turntable 15 is arranged inside the reaction container 9. This turntable 15 is connected to a motor 17 via a rotating shaft 16 that is provided to pass through the bottom of the reaction container 9 in an airtight manner. A cassette 19 is mounted on the turntable 15 for horizontally placing wafers 18 to be processed in multiple stages. The discharge side of this reaction vessel 9 is discharge 1!
'20. It is connected to a discharge system (not shown) via a discharge valve 27.

On the other hand, this device is equipped with a pulse controller 22. The pulse signal from the pulse controller 22 is given to the electromagnetic valve 3 and the microwave power source 6, and these are driven in synchronization with the pulse signal.

In the CDE apparatus configured in this way, taking polysilicon etching as an example, CF4 from the gas source is
The mixed gas of
and stored there under high pressure. The solenoid valve 3 opens the gas flow path in synchronization with a pulse signal from a pulse controller 22 as shown in FIG. Therefore, the mixed gas stored in the gas container 2 is supplied to the plasma generator 4 as a gas pulse at ^ pressure. Since the microwave power source 6 outputs microwaves in synchronization with the pulse signal, the gas pulse is turned into plasma by high-power microwave irradiation from the waveguide 7, becomes a highly concentrated active gas, and enters the reaction vessel 9. be introduced inside. Reaction container 9
The active gas introduced into the inside of the wafer 18 is dispersed and rectified by a dispersion plate 11 and a rectifying plate 13, and then used for etching each wafer 18.

Since the active gas introduced into the reaction vessel 9 has an extremely high concentration, the etching rate of each wafer 18 is determined not by the gas concentration but by the reaction rate. therefore,
Etching progresses uniformly even if the concentration of the active gas supplied to each wafer 18 varies somewhat. The reaction products are discharged via the discharge pipe 20 and discharge valve 2) continuously or during periods when said gas pulses are not introduced.

Thus, etching is completed by repeating the above batch process multiple times.

Thus, according to this embodiment, a large number of wafers can be uniformly etched.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a dry etching apparatus according to an embodiment of the present invention, and FIG. 2 is a waveform diagram for explaining the operation of the same apparatus. DESCRIPTION OF SYMBOLS 1... Flow rate adjustment valve, 2... Gas container, 3... Solenoid valve, 4... Plasma generator, 5... Discharge tube, 7...
... Waveguide, 8... Plasma transport tube, 9... Reaction vessel, 11.12... Dispersion plate, 13.14... Rectifier plate, 15... Turntable, 16... Rotating axis, 17
...Motor, 18...Wafer, 19...Cassette, 20...Discharge pipe, 2)...Discharge valve. Applicant's representative Patent attorney Shikihiko Suzue Figure 1. Figure 2, p-i child. N

Claims (2)

[Claims] (1) A plasma generator for activating the etching gas is interposed in a gas flow path between a reaction container that accommodates the object to be processed and an etching gas supply source that supplies etching gas to the reaction container. In the dry etching apparatus, the etching gas supply source intermittently supplies a high concentration etching gas to the reaction vessel, and the plasma generator supplies the high concentration etching gas in synchronization with the introduction timing of the high concentration etching gas. A dry etching apparatus characterized in that it irradiates a concentrated etching gas with high-power microwaves. (2) The dry etching apparatus according to claim 1, wherein the objects to be processed are arranged in multiple stages inside the reaction vessel.