JPH07211681A - Method and equipment for cleaning - Google Patents

Abstract

PURPOSE:To remove impurities positively from the surface of a semiconductor wafer. CONSTITUTION:An inert gas fed from a gas cylinder is subjected to pressure reduction by a pressure reducing valve, flow limitation by a mass flow controller and then passed through a filter and a purifier where particles and impurities are removed thus feeding a high purity inert gas into a heating chamber. On the other hand, a semiconductor wafer 1 loaded to a loader 12 is transferred into the heating chamber by means of a transfer unit 14. The atmospheric temperature in the heating chamber is sustained at a high level of about 200 deg.C by means of a heater and the semiconductor wafer 1 is baked in that inert gas atmosphere and cleaned. During the cleaning operation, an APIMS 11 analyzes the gas constantly and delivers the results of analysis to a control means 15. If the impurity concentration is lower than a preset level, the cleaning operation is ended otherwise the cleaning operation is continued until the preset impurity concentration is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for removing impurities, and more particularly to a technique effectively applied to cleaning a semiconductor wafer used in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art To clean a semiconductor wafer in a semiconductor manufacturing process, an oxide film and particles on the surface of the semiconductor wafer are removed by immersing the semiconductor wafer in a dip tank in which a cleaning agent such as hydrofluoric acid is injected.

After that, the semiconductor wafer is washed with pure water and dried by shaking off the water on the surface by utilizing the centrifugal force of high-speed rotation. After the water is replaced with an organic solvent having a low latent heat of vaporization, the organic solvent Water is removed by a vapor dryer or the like that is dried by heating with steam.

[0004]

However, in the conventional semiconductor wafer cleaning technique as described above, the surface structure has a high step due to high integration of semiconductor devices,
It has become difficult to clean the surface of a semiconductor wafer.

For example, in a DRAM semiconductor device, the device structure shifts from a two-dimensional device to a three-dimensional device at the boundary of 1 megabit, and a slight amount of resist or cleaning agent remains on the step portion during the manufacturing process of the insulating film of the memory cell. However, the leakage current of the insulating film will increase.

Further, it is difficult to sufficiently remove the impurities in the deep groove having a high aspect ratio in the cleaning in the wet process using the solution.

This is because the solution does not sufficiently penetrate into the fine groove having a width of 0.5 μm and a depth of several μm, and it is particularly difficult to remove impurities at the corners of the groove.

There is also a method of heating and heating a semiconductor wafer in an ultra-high vacuum to remove fine organic substances, but it takes a long time to establish an ultra-high vacuum and the semiconductor is not exposed to the atmosphere. Adsorption of atmospheric components and adhesion of particles to the wafer pose problems.

Further, since a method of monitoring impurities desorbed components in real time has not been established, it has been difficult to determine the end point of cleaning.

An object of the present invention is to provide a cleaning method and a cleaning device for surely removing impurities adhering to the surface of a semiconductor wafer.

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

[0012]

Of the inventions disclosed in the present application, a representative one will be briefly described below.
It is as follows.

That is, in the cleaning method of the present invention, cleaning is performed by exposing the object to be cleaned to an atmosphere of heated high-purity inert gas.

Further, in the cleaning method of the present invention, the impurities in the inert gas are analyzed, and the cleaning is terminated when the concentration of the impurities falls below a predetermined value.

Further, the cleaning apparatus of the present invention comprises a processing chamber for accommodating an object to be cleaned, a heating means for heating the processing chamber, a pressure reducing means for reducing the pressure of the inert gas supplied into the processing chamber, Flow rate adjusting means for adjusting the flow rate of the active gas,
The removing means removes impurities and particles of the inert gas.

In the cleaning apparatus of the present invention, an analyzing means for analyzing the component of impurities desorbed from the object to be cleaned is provided on the exhaust gas side of the inert gas in the processing chamber, and a result analyzed by the analyzing means is displayed. A control means for controlling the cleaning time is provided on the base.

Further, in the cleaning apparatus of the present invention, the transfer means is provided with a transfer direction switching means for switching the transfer direction of the objects to be cleaned and a selection means for selecting the objects to be cleaned.

Further, in the cleaning apparatus of the present invention, the analysis means is an APIMS for ionizing and analyzing impurities in the atmosphere.
(Atomospheric Pressure Io
nitization Mass Spectrometer
r: atmospheric pressure ionization mass spectrometer).

[0019]

According to the above-described cleaning method and cleaning apparatus of the present invention, it is possible to remove the amount and composition of impurities such as water, ammonia and organic substances adhering to the surface of the semiconductor wafer while monitoring them.

As a result, the impurities on the surface of the semiconductor wafer can be reliably and efficiently removed in a short time.

Further, it is possible to eliminate defective semiconductors such as deterioration of electrical characteristics of semiconductor devices due to impurities on the surface of the semiconductor wafer.

[0022]

Embodiments of the present invention will now be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a schematic view of the essential parts of a semiconductor wafer cleaning apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a semiconductor wafer cleaning apparatus and API according to Embodiment 1 of the present invention.
FIG. 3 is a main part configuration diagram in which an MS is connected, and FIG. 3 is a main part system configuration diagram of the semiconductor wafer cleaning apparatus according to the first embodiment.

In the first embodiment, the cleaning apparatus 2 for the semiconductor wafer 1 includes a heating chamber (processing chamber) 3 made of quartz or the like for holding the semiconductor wafer 1 in an atmosphere of an inert gas such as nitrogen or argon. A heater (heating means) 4 for heating the heating chamber 3, a gas cylinder 5 for supplying a high-purity inert gas, a pressure reducing valve (pressure reducing means) 6 for reducing the pressure of the gas supplied from the gas cylinder 5, A mass flow controller (flow rate adjusting means) 7 for adjusting the flow rate of the active gas, a filter (removing means) 8 for removing particles and the like in the gas, and a purifier (removing means) 9 for removing impurities in the gas are piped. Connected by 10.

Further, as shown in FIG. 2, the heating chamber 3 is provided with a supply port 3a for introducing an inert gas and an exhaust port 3b for exhausting the inert gas, and the exhaust port 3b is provided with impurities. The APIMS 11 for analyzing the components of is connected by the gas collection pipe 10a.

Next, as shown in FIG. 3, the system configuration of this cleaning apparatus is such that the loader 12 in which the semiconductor wafer 1 before cleaning is stored, the cleaning apparatus 2, and the semiconductor wafer 1 after cleaning.
And an unloader 13 for accommodating the semiconductor wafer 1 and the unloader 13 for storing the semiconductor wafer 1.

Further, the cleaning device 2 and the APIMS 11
Is connected to and controlled by the control means 15 for controlling the cleaning operation.

Next, the operation of this embodiment will be described.

The inert gas supplied from the gas cylinder 5 is decompressed to a predetermined pressure by the pressure reducing valve 6, and the mass flow controller 7 adjusts the predetermined flow rate.

Then, by removing particles and impurities in the gas with the filter 8 and the purifier 9,
Further, a high-purity inert gas is supplied into the heating chamber 3 through the supply port 3a.

The ambient temperature in the heating chamber 3 is maintained at a high temperature of about 200 ° C. by the heater 4. Next, the semiconductor wafer 1 stored in the loader 12 before cleaning is transferred into the heating chamber 3 heated by the transfer device 14. Then, the impurities are desorbed by baking the semiconductor wafer 1 in a high temperature inert gas atmosphere.

During this cleaning, the APIMS 11 is connected to the exhaust port 3
The component in the gas exhausted from b and the amount of separation are constantly analyzed, and the analysis result is input to the control means 15. Based on the data, the control unit 15 performs the cleaning operation when the impurity concentration in the inert gas is lower than the preset specified value, that is, when the amount of impurities desorbed from the semiconductor wafer 1 decreases. If the impurity concentration in the inert gas is higher than the specified value, that is, if the amount of impurities desorbed from the semiconductor wafer 1 is large, the cleaning operation is continued until the impurity concentration is equal to or lower than the specified value.

Then, when the amount of impurities desorbed from the semiconductor wafer 1 becomes small and the impurity concentration becomes lower than the specified value, the cleaning operation is terminated, and the semiconductor wafer 1 in the heating chamber 3 is transferred under the control of the control means 15. It is transported by the machine 14 and stored in the unloader 13.

As a result, according to the first embodiment, the impurities adhering to the semiconductor wafer 1 can be reliably removed while being monitored by the APIMS 11.

In the first embodiment, the cleaning of the semiconductor wafer 1 is a single-wafer cleaning method. However, the semiconductor wafer 1 is fixed to a cassette or the like and a batch cleaning method of cleaning a plurality of semiconductor wafers 1 at a time is performed. By doing so, cleaning can be performed more efficiently.

(Embodiment 2) FIG. 4 is a system configuration diagram of essential parts of a semiconductor wafer cleaning apparatus according to Embodiment 2 of the present invention.

In the second embodiment, as shown in FIG. 4, the loader 12 that stores the semiconductor wafer 1 before cleaning is used.
Between the cleaning device 2 and the cleaning device 2, a transfer direction switching unit 16 for switching the transfer direction of the wafer is provided, and they are connected by the transfer device 14.

Further, between the cleaning device 2 and the unloader 13 for housing the semiconductor wafer 1 after cleaning, there is a selecting means 17 for selecting between the semiconductor wafer 1 which has been cleaned and the semiconductor wafer 1 which is to be cleaned again. Provided, they also have a carrier 1
Connected by four.

Further, a cleaning device 2, a loader 12, and a transfer direction switching means 16 are provided, and the transfer direction switching means 16 and the sorting means 17 are connected by a transfer machine (transfer means) 14a. There is.

Next, the operation will be described.

The semiconductor wafer 1 before cleaning stored in the loader 12 is transferred into the heating chamber of the cleaning device 2 by the transfer device 14 and cleaning is performed. This cleaning is performed for a predetermined time, and when the predetermined time is reached, the APIMS 11
The component and desorption amount in the inert gas exhausted from the exhaust port 3b are analyzed by.

Then, this analysis result is output to the control means 15, and based on the data, the control means 15 determines the carrier 14 and the sorting machine if the impurity concentration is lower than the preset specified value. The means 17 is controlled so that the unloader 13 stores the semiconductor wafer 1.

The semiconductor wafer 1 having an impurity concentration higher than the preset specified value and insufficiently cleaned is controlled by the control means 15 from the cleaning device 2 to the carrier 14.
Then, it is conveyed to the sorting means 17. Then, the selecting means 17 transfers the semiconductor wafers 1 that have not been cleaned sufficiently to the conveying means 14a.
To the transport direction switching means 16,
The cleaning of the semiconductor wafer 1 is started again. Then, the above-described operation is repeated until the impurity concentration of the semiconductor wafer 1 becomes equal to or lower than the specified value, so that cleaning is performed.

Then, when the impurity concentration falls below the specified value, the control means 15 controls the carrier 14 to store the semiconductor wafer 1 in the unloader 13.

As a result, also in the second embodiment, the impurities attached on the semiconductor wafer 1 can be reliably removed while being monitored by the APIMS 11.

Further, also in the second embodiment, the semiconductor wafer 1
The cleaning is performed in a single wafer method, but a batch method in which a plurality of semiconductor wafers 1 are cleaned at one time enables more efficient cleaning.

Alternatively, the semiconductor wafers 1 that have been washed poorly and have been carried out by the transfer direction switching means 16 may be stocked, and a plurality of semiconductor wafers 1 that have been washed poorly may be processed in a batch manner.

Although the invention made by the present inventor has been described based on the embodiments, the present invention is not limited to the embodiments and various modifications can be made without departing from the scope of the invention. There is no end.

For example, the heating means may be other than the heater 4 of the above-mentioned embodiment, and may be an infrared lamp, an ultraviolet lamp, a halogen lamp, a high frequency heating device or the like as long as it can raise the atmospheric temperature in the heating chamber 3.

The cleaning of the semiconductor wafer 1 does not need to be provided with the control means 15, and the same effect can be obtained even if the operator manually operates while monitoring the analysis result of the APIMS 11.

Furthermore, the present invention is not limited to the cleaning of the semiconductor wafer 1 of Embodiments 1 and 2 described above, and any cleaning product for removing impurities and foreign substances in micro units such as medical equipment can be applied. You can

[0052]

The effects obtained by the typical ones of the inventions disclosed by the present application will be briefly described as follows.
It is as follows.

(1) According to the present invention, since cleaning can be performed while monitoring the amount and composition of the impurities adhering to the surface of the semiconductor wafer, the impurities can be reliably removed.

(2) Further, in the present invention, due to the above (1), defects due to the deterioration of the electrical characteristics of the semiconductor element due to the impurities on the semiconductor surface are eliminated, and the yield of the semiconductor device can be improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of essential parts of a semiconductor wafer cleaning apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a main part in which a semiconductor wafer cleaning apparatus and an APIMS according to the first embodiment of the present invention are connected.

FIG. 3 is a system configuration diagram of essential parts of a semiconductor wafer cleaning apparatus according to a first embodiment of the present invention.

FIG. 4 is a system configuration diagram of essential parts of a semiconductor wafer cleaning apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor wafer 2 Cleaning device 3 Heating chamber (processing chamber) 3a Supply port 3b Exhaust port 4 Heater (heating means) 5 Gas cylinder 6 Pressure reducing valve (pressure reducing means) 7 Mass flow controller (flow rate adjusting means) 8 Filter (removing means) 9 Purification Container (removal means) 10 Pipe 10a Gas collection tube 11 APIMS 12 Loader 13 Unloader 14 Transport machine (transport means) 14a Transport machine (transport means) 15 Control means 16 Transport direction switching means 17 Sorting means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuo Nakano 3-3, Fujibashi 2-3, Ome-shi, Tokyo Within Hitachi Tokyo Electronics Co., Ltd. (72) Keiji Hasumi 3-3 2-3 Fujibashi, Ome-shi, Tokyo Hitachi Higashi Kyo Electronics Co., Ltd. (72) Inventor Yasuhiro Mitsui 1-280 Higashi Koigakubo, Kokubunji City, Tokyo Inside Central Research Laboratory, Hitachi, Ltd. (72) Inventor Katsuhiko Ito 5-20-1 Kamimizuhonmachi, Kodaira-shi, Tokyo Hitachi, Ltd. Semiconductor Division

Claims (6)

[Claims] 1. A cleaning method, which comprises cleaning an object to be cleaned by exposing it to an atmosphere of heated high-purity inert gas. 2. The cleaning method according to claim 1, wherein impurities in the inert gas are analyzed, and cleaning is performed until the concentration of the impurities becomes a predetermined value or less. 3. A processing chamber for accommodating an object to be cleaned, heating means for heating the processing chamber, pressure reducing means for reducing the pressure of the inert gas supplied into the processing chamber, and flow rate of the inert gas. A cleaning apparatus comprising: a flow rate adjusting unit for adjusting, a removing unit for removing impurities and particles of the inert gas, and a carrying unit for carrying the object to be cleaned. 4. An analysis means for analyzing the components of impurities desorbed from the object to be cleaned on the exhaust port side of the processing chamber, and a control for controlling the cleaning time and the transfer means according to the analysis result from the analysis means. The cleaning apparatus according to claim 3, further comprising: 5. The transport means is provided with a transport direction switching means for switching the transport direction of the article to be cleaned and a sorting means for sorting the article to be cleaned. The cleaning device described. 6. The cleaning apparatus according to claim 4, wherein the analysis means is APIMS.