JPS6332926A - Ashing apparatus - Google Patents

Abstract

PURPOSE:To enable the title apparatus to cope with single large diameter semiconductor wafer processing, etc., with the high ashing speed of photoresist films without damaging wafers by a method wherein gas flow outlets which are provided so as to closely face the wafer in a semiconductor wafer treatment chamber and make gas flow out toward the wafer and an exhaust part which discharges exhaust gas out of the treatment chamber through openings provided around the wafer are provided. CONSTITUTION:A semiconductor wafer 12 is heated by a heater 15 which is built in a placing table 13 and controlled by a temperature controller 14. The flow of ozone- containing oxygen gas supplied by an oxygen supply source 20 and the flow rate of an ozone generator 21 is regulated by a gas flow rate regulator 19 and the oxygen gas is made to flow out toward the semiconductor wafer 12 through a diffusion plate 17b and discharged from an exhaust part 25 by an exhaust device 23. At that time, gas flows which flow from gas flow outlets 17 toward the wafer 12 and from the center part of the wafer 12 to the circumferential parts and are discharged through a plurality of discharge openings 22 provided around the wafer 12 are formed between the gas flow outlets 17 and the exhaust part 25. Therefore, uniform ashing speed can be obtained over the whole surface of the wafer 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an ashing device that oxidizes and removes a photoresist film or the like deposited on a semiconductor wafer using ozone.

(Prior Art) Formation of fine patterns in semiconductor integrated circuits is generally performed by etching a base film formed on a semiconductor wafer using an organic polymer photoresist film formed by exposure and development as a mask. It will be done.

Therefore, the photoresist film used as a mask needs to be removed from the surface of the semiconductor wafer after the etching process.

An ashing process is performed to remove the photoresist film in such a case.

This ashing process is used to remove resists, clean silicone wafers, masks, ink, solvent residues, etc., and is suitable for dry cleaning in semiconductor processes.

As an ashing device for removing a photoresist film, one that uses oxygen plasma is generally used.

The 7-thinning device for photoresist films using oxygen plasma places a semiconductor wafer with a photoresist film in a processing chamber, converts the oxygen gas introduced into the processing chamber into plasma using a high-frequency electric field, and removes organic matter from the generated oxygen atomic radicals. The photoresist film is oxidized to produce carbon dioxide, -
Removed by decomposition into carbon oxide and water.

Furthermore, there is an ashing device that generates oxygen atom radicals by irradiating ultraviolet rays and performs ashing processing in batch processing.

Figure 17 shows an ashing device that generates oxygen atom radicals by irradiating ultraviolet rays.
A large number of semiconductor wafers 2 are arranged vertically at predetermined intervals, and ultraviolet light from an ultraviolet light emitting tube 3 installed at the top of the processing chamber 1 is transmitted to a transparent material such as quartz installed on the top surface of the processing chamber 1. The oxygen is irradiated through a window 4, and the oxygen filled in the processing chamber 1 is excited to generate ozone. Oxygen atom radicals generated from this ozone atmosphere act on the semiconductor wafer 2 to perform an ashing process.

(Problem to be solved by the invention) However, behind the conventional ashing device described above,
In an ashing apparatus using oxygen plasma, the semiconductor wafer is irradiated with ions and electrons accelerated by an electric field existing in the plasma, which inevitably causes damage to the semiconductor wafer.

Furthermore, in ashing equipment that uses ultraviolet rays, the semiconductor wafer is not damaged by the plasma described above;
Since the ashing speed is slow at 50 to 150 nm/min and the processing takes time, there is a problem in that single-wafer processing in which semiconductor wafers are processed one by one, which is suitable for processing large-diameter semiconductor wafers, for example, cannot be performed.

The present invention has been made in response to such conventional circumstances,
It is an object of the present invention to provide an ashing device that does not damage semiconductor wafers, has a high ashing speed for photoresist films, and can handle single-wafer processing of large-diameter semiconductor wafers.

[Structure of the Invention] (Means for Solving the Problems) That is, the present invention provides an ashing device that oxidizes and removes a film deposited on the surface of a semiconductor wafer with a gas containing ozone, in which the semiconductor wafer is accommodated. a processing chamber, a gas outlet disposed close to and opposite to the semiconductor wafer in the processing chamber, and discharging the gas toward the semiconductor wafer; and an opening disposed surrounding the semiconductor wafer to discharge the exhaust gas. The method is characterized by comprising an exhaust section for discharging the air to the outside of the processing chamber.

(Function) The ashing apparatus W of the present invention is provided with a gas outlet portion that is close to and faces the semiconductor wafer and causes the gas containing ozone to flow out toward the semiconductor wafer. By flowing out oxygen gas containing ozone from this gas outlet, new ozone can be supplied to the semiconductor wafer surface, promoting the oxidation chemical reaction between oxygen atomic radicals and the film deposited on the semiconductor wafer. can be done.

In addition, the ozone-containing gas discharged toward the semiconductor wafer is uniformly directed toward the outer periphery of the semiconductor wafer through an exhaust section with openings arranged around the semiconductor wafer, and is released as exhaust gas. It is discharged from this exhaust section. Therefore, a uniform gas flow is formed on the surface of the semiconductor wafer from the center toward the outer periphery, making it possible to obtain a high and uniform ashing rate for the entire semiconductor wafer.

(Example) Hereinafter, an example of the ashing device of the present invention will be described with reference to the drawings.

FIG. 1 shows an ashing apparatus according to an embodiment of the present invention. In the ashing apparatus of this embodiment, a mounting table 13 for holding a semiconductor wafer 12 by suction with, for example, a vacuum chuck is arranged in a processing chamber 11. This mounting table 1
3 is a heater 15 controlled by the temperature control device 14;
It has a built-in structure and is configured to be movable up and down by a lifting device 16.

A gas outflow section 17 is disposed above the mounting table 13 and includes a conical cone section 17a and a diffusion plate 17b which is disposed at the opening of the cone section 17a and is made of a sintered body such as metal or ceramic. This gas outlet section 17 is cooled by cooling water or the like circulated from a cooling device 18.

Also, is the gas outflow portion 17 a gas flow? These gas flow rate regulators 19 are connected to the oxygen supply source 2.
The ozone generator 21 is connected to the ozone generator 21, which is connected to the ozone generator 21, which is connected to

In the lower part of the processing chamber 11, as shown in FIGS. 2 and 3, there are a plurality of exhaust ports 22 arranged around the mounting table 13 and having a diameter of, for example, 10 to 15 mm. An exhaust section 25 is provided which includes a pressure equalizing pipe 24 that collects exhaust ports 22 and connects them to an exhaust device 23. Note that FIG. 3 shows a vertical cross section taken along line A-A shown in FIG. 2.

The ashing device of this embodiment having the above configuration performs ashing as follows.

First, the mounting table 13 is lowered by the lifting device 16, and a gap is provided between it and the gas outlet 17 in which an arm or the like of a wafer transfer device (not shown) is introduced, and the semiconductor wafer 12 is moved into the wafer transfer device, etc. is placed on the mounting table 13 and held by suction.

After that, the mounting table 13 is raised by the lifting device 16,
The distance between the diffusion plate 17b of the gas outlet portion 17 and the surface of the semiconductor wafer 12 is set to a predetermined distance of, for example, about 0.5 to 20 mm. In this case, the gas outlet portion 17 may be moved up and down by a lifting device.

Then, the heater 15 built into the mounting table 13 is controlled by the temperature control device 14, and the semiconductor wafer 12 is
Heat to a range of about 'C to 500'C and use an oxygen supply source of 20
The oxygen gas containing ozone supplied from the ozone generator 21 is controlled by the gas flow rate regulator 19 at a flow rate of, for example, 3 to 15. e/min, the gas flows out from the diffusion plate 17b toward the semiconductor wafer 12, and is evacuated from the exhaust section 25 using the exhaust device 23 so that the gas pressure in the processing chamber 11 is in the range of approximately 700 to 200 Torr. do.

At this time, there is a second
As shown by arrows in FIG. 4, the gas flows from the outflow portion 17 toward the semiconductor wafer 12, from the center of the semiconductor wafer 12 to the periphery, and through a plurality of exhaust ports 22 provided around the semiconductor wafer 12. A flow of gas is formed to be exhausted from the air. That is, a uniform gas flow is formed on the surface of the semiconductor wafer 12 from the center of the semiconductor wafer 12 toward the outer periphery. Therefore, a uniform ashing rate can be obtained over the entire surface of the semiconductor wafer 12.

The lifespan of ozone generated by the ozone generator 21 is
As shown in the graph of FIG. 5, where the vertical axis represents the ozone decomposition half-life and the horizontal axis represents the temperature of the ozone-containing gas, the lifetime of ozone rapidly shortens as the temperature increases.

For this reason, it is preferable that the temperature of the gas outlet part 17 is about 25°C or less, while the temperature of the semiconductor wafer 12 is 1.
It is preferable to heat to about 50'C or more.

In the graph of FIG. 6, the vertical axis is the ashing speed, the horizontal axis is the flow rate of the ozone-containing gas, and the distance between the gas outlet 17 and the semiconductor wafer 12 in the ashing apparatus of this embodiment described above is a parameter. It shows the change in ashing rate when an inch semiconductor wafer 12 is heated to 300'C.

Note that the ozone concentration is adjusted to be approximately 3 to 10% by weight. As can be seen from this graph, in the ashing apparatus of this embodiment, the distance between the semiconductor wafer 12 and the gas outlet portion 17 is several mTl1, and the gas flow rate containing ozone is 2 to 40 Si2. (Sβ is the flow rate converted to room temperature and normal pressure), so the ashing speed can be increased from 1 to @
High-speed ashing processing of μm/min can be performed.

In this embodiment, the gas outlet portion 17 is replaced by the cone portion 17.
a and a diffuser plate 17b made of a sintered body of metal or ceramic, but the present invention is not limited to this embodiment. For example, the diffuser plate may include a plurality of concentric circles as shown in FIG. Alternatively, it may be a diffuser plate 37b with a small hole as shown in No. 8Δ, an enlarged UNJ 7b with a linear slit as shown in No. 9, or an enlarged UNJ 7b with a linear slit as shown in No. As shown, a diffusion plate 57b, which has small holes of different sizes arranged regularly,
A political board 67 with spiral slits as shown in Figure 1.
b etc. may be arranged. Further, the cone portion 7a is not conical, but has a cylindrical shape 27a as shown in FIG.
etc. may also be configured.

Furthermore, the exhaust port 22 of the exhaust section 25 is shown in FIG.
As shown in FIG. 14, which is a longitudinal cross-sectional view taken along the line B-B shown in FIG. 3, the exhaust port 22a may be composed of annularly arranged slits. Further, such a slit 22a may be arranged so as to surround the semiconductor wafer 12, for example, as shown in FIG.
The slit 22b may be continuous in a ring shape, and the first
As shown in FIG. 6, a partially discontinuous horseshoe-shaped slit 22b may be used.

Also, in this example, the case of a photoresist film as an ashing target was explained, but it can be applied to various things such as ink removal and solvent removal, and any ashing target can be used as long as it can be removed by oxidation. The ozone-containing gas is not limited to oxygen; it is also possible to use a gas that does not react with ozone, or even an inert gas such as N2, Ar, Ne, etc., containing ozone.

(Effects of the Invention) As described above, the ashing device of the present invention does not damage semiconductor wafers and the ashing speed is uniform and high, so even large-diameter semiconductor wafers can be ashed in a short time by single-wafer processing. can be done.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an ashing device according to an embodiment of the present invention, FIG. 2 is a top view showing the main parts of FIG. 1, and FIG.
Figure 4 is an explanatory diagram showing the flow of gas, Figure 5 is a graph showing the relationship between ozone half-life and temperature, and Figure 6 is a graph showing the relationship between ashing rate and ozone. Graphs showing the relationship between the contained gas flow rate and the distance between the gas outlet and the semiconductor wafer, FIGS. 7 to 11 are bottom views showing modified examples of the gas outlet, and FIG. 12 shows modified examples of the gas outlet. 13 is a top view showing a modified example of the exhaust section, FIG. 14 is a longitudinal sectional view taken along line B-B in FIG. 13, and FIG.
1 to 16 are top views showing modified examples of the exhaust section, and FIG. 17 is a configuration diagram showing a conventional ashing device. 11... Processing chamber, 12... Semiconductor wafer, 17... Gas outlet, one... Waste flow rate regulator, 21...・Ozone generator, 22・
...Exhaust port, 23...Exhaust device, 24.
... Pressure equalization pipe, 25 ... Exhaust section. Applicant Tokyo Electron Co., Ltd. Agent Patent Attorney Sa Suyama - Figure 1 Figure 3 Figure 2 Figure 4 UJν [T Kado (0C) Figure 5 Figure 6'! Figure 7Figure 8Figure 9Figure 10Figure 11Figure 12Figure 14Figure 15Figure 16Figure 17

Claims (2)

[Claims] (1) In an ashing device that removes a film deposited on the surface of a semiconductor wafer by oxidizing it with a gas containing ozone, there is a processing chamber that accommodates the semiconductor wafer, and a processing chamber that is close to and faces the semiconductor wafer within the processing chamber. a gas outflow portion arranged to cause the gas to flow out toward the semiconductor wafer;
An ashing device comprising: an exhaust section that discharges exhaust gas to the outside of the processing chamber from an opening arranged around the semiconductor wafer. (2) The ashing device according to claim 1, wherein the opening arranged around the wafer is a large number of openings arranged coaxially with the wafer.