JP3123954B2 - Wet etching apparatus and processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wet etching apparatus, and more particularly, to a silicon nitride film etching apparatus and a silicon oxide film etching apparatus.

[0002]

2. Description of the Related Art FIG. 3 is a schematic diagram showing the prior art. Conventionally, a dip type wet etching apparatus includes an etching tank 2, a heater or a cooler 3, a circulation pump 4 and a filter 5, and the same applies to a silicon nitride film etching apparatus and a silicon oxide film etching apparatus. is there.

The etching solution 1 discharged from the circulation pump 4 passes through the filter 5, enters the etching bath 2, and the etching solution 1 a overflowing from the etching bath 2 is sent to the circulation pump 4 again. At this time, particles in the etching treatment liquid 1 are collected by the filter 5 and the inside of the etching treatment tank 2 is usually kept clean (see JP-A-4-103781).

[0004]

A problem in the prior art is particles generated when a silicon nitride film is etched using high-temperature phosphoric acid. These particles adhere to silicon wafers in large quantities and reduce the product yield in the manufacture of semiconductor integrated circuits.

Another problem is that the amount of phosphoric acid used increases, the amount of filter used increases, and the downtime of the apparatus due to filter replacement increases.

The reason for this is that particles generated when etching the silicon nitride film increase with an increase in the processing amount and are adsorbed on the filter film, thereby deteriorating the particle removal performance as a filter. Further, the particles gradually accumulate in the filter, do not return to the original state even when the etching treatment liquid (phosphoric acid) is replaced, and eventually the filter is clogged. That is,
Since the conventional device does not have a function of periodically removing particles attached to the filter, the above-described problem has occurred.

The reason why the amount of phosphoric acid used and the amount of filter used are increased is that phosphoric acid exchange and filter exchange are frequently performed as one of means for solving the above-mentioned problem of particles. That is, phosphoric acid is exchanged until a large amount of particles are generated. Similarly, the filter is replaced before the particle removal function is deteriorated. In general, the frequency of phosphoric acid exchange is once / one day to three days, the frequency of filter exchange is once / several months to one year, and the time required for filter exchange is about five hours / one time. The above problem can be solved if the particle removing function of the filter can be stabilized for a long time.

It is an object of the present invention to provide a wet etching apparatus and a processing method capable of efficiently removing particles by always keeping a filter in a normal state. As a result, it is possible to improve the yield in the manufacture of semiconductor integrated circuits, reduce the amount of phosphoric acid and filters used, and improve the productivity by shortening the device non-operation time due to the number of filter replacements.

[0009]

According to the present invention, an etching bath containing an etching solution, a heater for heating the etching solution, a cooler for cooling the etching solution, In a dipping type wet etching apparatus having a pump for circulating liquid and a filter used for removing particles, wet etching processing capable of performing etching of a silicon nitride film and etching of a silicon oxide film in a single bath. A processing method in which etching of a silicon nitride film and etching of a silicon oxide film are alternately performed in an apparatus and a single bath is obtained.

Although the conventional silicon nitride film wet etching apparatus has only a phosphoric acid supply line used for etching a silicon nitride film, the wet etching apparatus of the present invention also has a hydrofluoric acid supply line. ing.

For this reason, after a certain period of use as a silicon nitride film wet etching apparatus, a chemical solution is exchanged and used as a silicon oxide film wet etching apparatus. If a chemical solution is exchanged again, the apparatus is used as a silicon nitride film wet etching apparatus. It is possible to

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a wet etching apparatus according to the first embodiment of the present invention.

As shown in FIG. 1, a phosphoric acid supply line 9 and a hydrofluoric acid supply line 10 are provided in an etching treatment tank 2 containing an etching treatment liquid 1. Further, a heater 7 for etching a silicon nitride film and a cooler 8 for etching a silicon oxide film are provided outside the etching processing tank 2. Hereinafter, the circulation pump 4 and the filter 5 are the same as those in the related art. The flow of the etching solution 1 flows in the direction of the arrow in FIG. 1, and the etching solution 1 discharged from the circulation pump 4 passes through the filter 5 to remove particles, and is then sent to the etching bath 2 to perform the etching process. The etching solution 1 a overflowing from the tank 2 is sent to the circulation pump 4 again.

Next, the wet etching method will be described. First, the etching solution 1 (phosphoric acid in this case) is supplied into the etching bath 2 from the phosphoric acid supply line 9 and the etching solution 1 is
After heating to 0 ° C., the silicon nitride film is etched for 3 days and drained. After the waste liquid, an etching treatment liquid (in this case, hydrofluoric acid) is supplied into the etching treatment tank 2 from a hydrofluoric acid supply line 10, and the etching treatment liquid 1 is cooled to 20 ° C. using a cooler 8 to form a silicon oxide film. The etching process is performed for 3 days to drain the liquid. The etching of the silicon nitride film is usually performed by alternately using the etching bath 2 for the etching of the silicon nitride film and the etching of the silicon oxide film, such as supplying phosphoric acid to the etching treatment tank 2 again. Phosphoric acid with much less particles than in the case of using only the treatment can be supplied.

This is because the particles generated when etching the silicon nitride film and adsorbed on the filter can be easily removed with hydrofluoric acid when etching the silicon oxide film, so that the filter always has a normal particle removing function. Because you can keep.

Next, a second embodiment of the present invention will be described. FIG. 2 is a schematic view showing a second embodiment of the present invention, as viewed from above. As shown in FIG.
The wet etching apparatus (11,
11a) are arranged in series, and a washing tank 12 is provided between them.

By arranging such processing apparatuses, it is possible to perform silicon nitride film etching and silicon oxide film etching processing with one apparatus. That is, phosphoric acid is supplied to one of the etching processing apparatus 11 and the etching processing apparatus 11a, and hydrofluoric acid is supplied to the other, and each is etched. Therefore, by alternately changing the etching solution of the silicon nitride film etching apparatus and the silicon oxide film etching apparatus, the particles generated during the silicon nitride film etching and adsorbed on the filter are etched as described above. At this time, the filter is always kept in a normal state because it is removed with hydrofluoric acid. If the etching solution is replaced at intervals of three days, particles adhering to the silicon wafer are significantly reduced, and the life of the filter is greatly extended.

As a result, the yield in semiconductor integrated circuit manufacturing is improved, the cost of the filter is reduced, and the downtime of the apparatus due to the replacement of the filter is greatly reduced.

Next, other effects will be described. As described above, by arranging the wet etching apparatuses of the present invention in series, continuous processing of silicon nitride film etching and silicon oxide film etching becomes possible. First, the silicon oxide film is etched in an etching bath containing hydrofluoric acid, and then washed with a washing bath 12. Next, the silicon nitride film is etched in an etching bath containing phosphoric acid.

Normally, a silicon nitride film is used as a mask for silicon oxidation in element isolation formation in the manufacture of a semiconductor integrated circuit. However, in the subsequent steps, a continuous process of silicon oxide film etching, silicon nitride film etching, and silicon oxide film etching is required. Becomes Conventionally, each process was performed by a separate apparatus, so that the total processing time required about 5 hours including the transport time from the apparatus to the apparatus. However, by employing the tank configuration of the present embodiment, the processing time becomes about 2 hours, and the present invention can also obtain an effect of shortening the construction period in manufacturing a semiconductor integrated circuit.

[0021]

The effect of the present invention is that the etching of the silicon nitride film and the etching of the silicon oxide film are alternately performed in a single bath, so that the inside of the etching bath is always kept clean. As a result, particles adhering to the silicon wafer are reduced, and the product yield is improved in semiconductor integrated circuit manufacturing. Further, the amount of the etching solution used and the amount of the filter used are reduced.

The reason is that particles generated when etching a silicon nitride film are silicon oxide-based particles and are easily dissolved by hydrofluoric acid used when etching a silicon oxide film. That is, the filter can always maintain normal performance and can reliably remove particles.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a second embodiment of the present invention.

FIG. 3 is a schematic diagram showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Etching processing liquid 1a Overflowing etching processing liquid 2 Etching processing tank 3 Heater or cooler 4 Circulation pump 5 Filter 6 Etching processing liquid supply line 7 Heater 8 Cooler 9 Phosphoric acid supply line 10 Hydrofluoric acid supply line 11, 11a Wet etching equipment 12 Rinse tank 13 Drying equipment

Claims (3)

(57) [Claims] An etching bath containing an etching solution; a heater for heating the etching solution;
A cold heat unit for cooling the etching solution, a pump for circulating the etching solution, in the wet etching apparatus of dip having a filter used to remove the particles (particles), the etch
The phosphoric acid supply line and the hydrofluoric acid supply line
A wet etching treatment apparatus, wherein the etching of the silicon nitride film and the etching of the silicon oxide film are alternately performed in a single bath. 2. The wet etching process according to claim 1.
Etching of silicon nitride film in a single tank
The feature is that the silicon oxide film is alternately etched.
Wet etching method. 3. The method according to claim 2, wherein the two wet etching devices are
The washing tank is cascaded, and phosphoric acid is added to one of the processing units.
And hydrofluoric acid to the other processing unit to supply silicon
Etching process of nitride film and silicon oxide film,
After using for a certain period of time, replace the etching solution
Wet etching characterized by performing a ching process
Processing equipment.