JPH0447454B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a sample processing device that forms a thin film on a sample or etches a thin film on a sample using a photochemical reaction, and particularly relates to an improvement in a light source. The present invention relates to a sample processing device with the following functions.

[Technical background of the invention and its problems]

Recently, a method has been developed in which a chemical reaction using light energy is used to decompose a compound gas and form a thin film on a sample such as a semiconductor wafer. This method is called photo-CVD, and has features such as being able to form films at lower temperatures and not being damaged by charged particles compared to normal thin film forming methods, and will play an important role in future thin film forming technology. It is attracting attention as a thing.

By the way, as a light source for emitting light energy used in this type of method, a discharge tube that generates light by discharge is generally used. The shape of the discharge tube is usually linear or U-shaped, and in order to irradiate a certain area, a method is adopted in which a plurality of discharge tubes are lined up. In this case, since a plurality of discharge tubes are arranged side by side, it is necessary to maintain a constant distance between the discharge tubes, which creates a space where no light is emitted, resulting in a decrease in the intensity of the irradiated light and non-uniformity. Further, there is a problem that the intensity of the irradiated light becomes non-uniform due to variations in the emission intensity of individual discharge tubes. This problem is a factor that hinders the formation of a uniform thin film using the optical CVD method.

The problem of non-uniformity of the irradiation light intensity mentioned above is a major drawback not only in the photo-CVD method but also in the photo-etching method that etches a thin film on a sample using a photochemical reaction. That is, the photo-etching method has a drawback in that the etching rate becomes non-uniform due to non-uniformity in the intensity of irradiated light.

[Purpose of the invention]

An object of the present invention is to provide a sample processing device that can uniformly irradiate a predetermined area with light, make the thickness of a thin film formed by optical CVD method uniform, and improve etching uniformity by optical etching. be.

[Summary of the invention]

The gist of the present invention is to use a single light source that emits light uniformly within a predetermined plane as a light source that emits light energy.

That is, in the present invention, a compound gas is introduced into a sample chamber containing a sample, and light from a light source is incident into the sample chamber to excite and decompose the gas, thereby forming a thin film on the sample or decomposing the thin film on the sample. In the sample processing apparatus for etching, the light source is a single discharge lamp, and the discharge lamp includes an airtight container having a surface parallel to the sample surface, and a container provided within the airtight container with a surface perpendicular to the plane. A strip-shaped discharge lamp that partitions the inside of the container and passes through the entire interior of the container is formed by a partition plate made of a member that transmits light from a light source, and electrodes provided at each end of the strip-shaped discharge lamp. This is a sample processing device characterized by:

More specifically, the light source is comprised of an airtight container having a surface parallel to the sample surface, and a strip-shaped strip provided inside the airtight container that partitions the inside of the container with a plurality of surfaces perpendicular to the above-mentioned plane and passes through the entire inside of the container. A single discharge lamp is constructed of a partition plate forming a discharge furnace and electrodes provided at both ends of the strip-shaped discharge furnace.

〔Effect of the invention〕

According to the present invention, since a single light source that emits light uniformly on a predetermined plane is used, there is no space between the light sources where no light is emitted, unlike when multiple light sources are used, and moreover, the individual light sources Problems such as variations in luminous intensity do not occur. Therefore, a desired area can be uniformly irradiated with light from the light source. Therefore, when applied to the optical CVD method, a thin film with a uniform thickness can be formed. Furthermore, when applied to a photoetching method, it becomes possible to perform uniform etching, and its usefulness in the field of semiconductor manufacturing technology is enormous.

[Embodiments of the invention]

FIG. 1 is a schematic configuration diagram showing an optical CVD apparatus according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a thin film forming container (sample chamber), and within this container 1 is accommodated a sample stage 3 on which a sample 2 made of, for example, a glass substrate is placed. A heater 4 for heating the sample 2 is provided inside the sample stage 3 . Also, container 1
A raw material gas containing a compound gas is introduced into the container 1 from a gas supply section 5, and the gas in the container 1 is exhausted by an exhaust pump 6.

On the other hand, a light source storage container 8 containing a light source 7 is provided above the thin film forming container 1 . light source 7
As shown in FIG. 2, the lamp consists of a single discharge lamp whose light emitting area (discharge area) is formed in a spiral shape. The light is incident into the container 1. Note that details regarding the light source 7 will be described later. In addition, an inert gas line 1 is provided in the container 8.
An inert gas (for example, nitrogen, argon, etc.) is passed through the tubes 0 and 11, thereby cooling the light source 7 and preventing the generation of ozone due to oxygen in the air.

By the way, the light source 7 is manufactured by the steps shown in FIGS. 3a to 3g. That is, first, a disk 32 made of synthetic quartz as shown in FIG. 3b is welded to the lower surface of a cylindrical body 31 made of synthetic quartz as shown in FIG.
As shown in figure c, the lower opening of the cylindrical body 31 is
Blocked at 2. Next, a dividing plate 33 made of a synthetic quartz plate curved in a spiral shape as shown in FIG.
are placed inside the cylindrical body 31 and welded to the disk 32 as shown in FIG. As a result, one spiral strip-shaped discharge path 34 as shown in FIG. 2 is formed. Next, as shown in FIG. 3f, the disk 3
Two holes are provided in a disk 35 similar to 2, and electrodes 3 are placed on the top surface of the disk 35 to close these holes.
Glass electrode storage tube 3 containing electrodes 6 and 37
8 and 39 are respectively welded. Next, Figure 3g
The lower surface of the disk 35 is welded to the upper surface of the cylindrical body 31 as shown in FIG. After that, the cylindrical body 31 and the disc 3
The inside of the container consisting of 2, 35, etc. is evacuated, and a gas containing mercury (for example, Ar-Hg) is evacuated into the container.
By enclosing a mixed gas), the light source 7
A discharge lamp (low-pressure mercury lamp) was completed. The light source 7 thus produced is arranged to face the sample 2 in the container 1 with the disk 32 side facing down.

In this device configured in this manner, the light emitting area of the light source 7 is spread over the circle formed by the cylinder 31 and the entire plane within the plane due to the spiral of one strip-shaped discharge path, so that it is uniform within the plane. It is possible to emit light energy. In experiments conducted by the present inventors, it was confirmed that a uniform light emitting surface was obtained when the light source 7 was turned on. Therefore, light can be uniformly irradiated into the container 1, and a thin film with a uniform thickness can be formed by the optical CVD method.

Here, since the light source 7 is made of synthetic quartz,
The light from the light source 7 is mainly ultraviolet light of 185 [nm] and 254 [nm]. Therefore, using ultraviolet light of the above wavelength, SiH ₄ (10%) diluted with H ₂ was used as the source gas.
Mixed gas with mercury vapor, raw material gas flow rate 50
The thin film was formed under the following conditions: [sccμ], gas pressure 1, sample temperature 200 [°C], and processing time 1 [h]. the result,
An amorphous silicon film with a thickness of 3600 Å was obtained on a glass substrate as Sample 2. The uniformity of this film was extremely good and was within ±5%. In addition, when a conventional U-shaped lamp is used as the light source 7, the film thickness is 2800 [Å] under the same conditions as above.
The uniformity was about ±10%.

As described above, according to the present apparatus, a thin film (amorphous silicon) can be formed uniformly on the sample 2 at a relatively high speed by the optical CVD method. Furthermore, since there is only one light source 7, non-uniformity in light irradiation due to variations in the intensity of light emitted from each light source, unlike when a plurality of light sources are used, does not occur. Furthermore, even if the luminescence intensity decreases over time, the overall luminescence intensity is uniform because there is only one light source 7, and therefore the amount of light irradiation becomes uneven over time. There is no inconvenience. and,
It is also extremely easy to correct this decrease in emission intensity using other conditions. For example, a light intensity measurement sensor is placed near the sample stage 3 to measure the irradiation intensity,
The time required to obtain a predetermined film thickness can be determined by using data that has been prepared in advance and determines the relationship between light intensity and film formation rate. In this case, since the light source 7 is unified, there is no variation over time unlike in the conventional method using a plurality of light sources, and measurement is easy. Moreover, the smallest sensor
For example, it is possible to measure the irradiation intensity even with one sensor. Moreover, instead of storing the electrodes 36 and 37 of the light source 7 inside the cylindrical body 31, the electrodes 36 and 37 of the light source 7 are
Since the electrodes 36 and 37 are housed in storage tubes 38 and 39 protruding from the electrodes 5, dark areas near the electrodes 36 and 37 do not occur on the lower surface side of the light source 7, thereby making it possible to further equalize the intensity of the irradiated light. There are advantages such as

Note that the present invention is not limited to the embodiments described above, and can be implemented with various modifications without departing from the gist thereof. For example, the shape of the light emitting part of the light source is not limited to a circular shape, but
There is no problem even if it is rectangular as shown in the figure.
In short, it is sufficient that the light-emitting region is formed of band-shaped light-emitting paths arranged in a predetermined plane, and that the light-emitting paths cover the entire surface of the plane without overlapping. Furthermore, the method of manufacturing the light source is not limited to the embodiments, and can be modified as appropriate. Furthermore, the light source is not limited to low-pressure mercury lamps;
Any device that emits light with a predetermined energy uniformly within a predetermined plane may be used.

Further, although the embodiments have been described with reference to an optical CVD apparatus, the present invention can also be applied to optical etching. Currently, the mainstream of VLSI microfabrication technology is
Reactive ion etching is a process in which ions generated from various reactive gases are incident perpendicularly onto the sample surface to etch the sample.
Etching (RIE). However, since this method uses charged particles such as electrons and ions, it causes irradiation damage such as substrate damage and electrostatic breakdown.
At present, we are struggling to remove these.

On the other hand, recently, research has been actively conducted on photoexcitation processes such as ultraviolet rays as dry etching techniques that do not use charged particles and cause damage without irradiation. In order to put these optical processes into practical use, a large diameter, uniform light source is essential, as in the case of thin film deposition. In other words, in recent years, there has been a remarkable trend toward larger diameter wafers, and 6- to 8-inch wafers are now being used, making it possible to use a batch processing method that takes into consideration not only etching uniformity but also throughput. Demand for large diameter light sources is increasing.

The present invention eliminates these problems, for example, by thermal oxidation on a 6-inch Si wafer.
When phosphorus-doped Poly-Si grown on SiO ₂ was irradiated with the lamp shown in Figure 2 in Cl ₂ , an etching uniformity of less than ±5% was obtained, which is extremely useful. has been proven.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing an optical CVD device according to an embodiment of the present invention, Fig. 2 is a plan view showing the structure of a light emitting part of a light source used in the above device, and Figs. 3 a to g.
4 is a perspective view showing the manufacturing process of the light source, and FIG. 4 is a plan view for explaining a modification. 1... Thin film formation container (sample chamber), 2... Sample,
3...Sample stand, 4...Heater, 5...Gas supply section, 6...Exhaust pump, 7...Light source, 8...Light source storage container, 9...Light transmission window, 31...Cylindrical body, 3
2, 35... Disk, 33... Split plate, 34... Discharge path (light emitting path), 36, 37... Electrode.

Claims (1)

[Claims] 1. A compound gas is introduced into a sample chamber in which a sample is housed, and light from a light source is incident into the sample chamber to excite and decompose the gas to form a thin film on the sample or to form a thin film on the sample. In a sample processing apparatus for etching a thin film, the light source is a single discharge lamp;
This discharge lamp includes an airtight container having a plane parallel to the sample surface, and a strip-shaped discharge lamp that is installed inside the airtight container and partitions the inside of the container with a plane perpendicular to the above-mentioned plane, passing through the entire inside of the container. A sample processing device comprising: a partition plate made of a member that transmits light from a light source; and electrodes provided at both ends of the strip-shaped discharge lamp. 2. The sample processing apparatus according to claim 1, wherein the electrode is housed in a storage tube that protrudes from inside the airtight container to a side opposite to the substrate side.