JPS63157422A - Ashing method - Google Patents

Abstract

PURPOSE:To prevent the ashing irregularity of a semiconductor wafer generated by interference with ashing gas between lines, by providing slit grooves between lines of apertures arranged in the form of a line. CONSTITUTION:When a switching valve 9a opens, a switching valve 9b shuts, and an ashing gas flows out on the surface of a semiconductor wafer is mounted on a mounting stand 15, from apertures 6a, passing through gas introducing pipes 8 via a valve 9a, On the other hand, when the valve 9b opens, the valve 9a shuts, and the ashing gas flows out on the surface of the wafer 16 from the valve 9b. Thereby, interference with the ashing gas between the neighbouring apertures 6a and 6b can be prevented. In the case of interference of the ashing gas between lines of apertures of 6a and 6b arranged in the form of a line, the ashing irregularity of the semiconductor wafer 16 can be prevented by exhausting the gas via exhaust outlets 19 arranged in the silt grooves 18.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an ashing method for removing a film deposited on a substrate to be processed.

(Prior Art) Generally, fine patterns for semiconductor integrated circuits are formed 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 must be removed from the surface of the semiconductor wafer after the etching process. Etching and ashing are performed to remove the photoresist film in such cases. In particular, etching and ashing processes using plasma are the mainstream. However, as the degree of integration of semiconductors improves, from 256M bits to IM bits and 2M bits, the wiring becomes thin and narrowly spaced, causing strong discharges in the plasma atmosphere, damaging semiconductor wafers and significantly reducing yields. 8. The applicant has developed an asher that does not suffer from this damage. Ashing processing is used to remove resist, clean silicon wafers and masks, as well as remove ink, solvent residue, etc., and is suitable for dry cleaning processing in semiconductor processes.

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

FIG. 3 shows an ashing device that generates oxygen atomic radicals through ultraviolet irradiation. Ultraviolet rays from an ultraviolet light emitting tube 3 installed in the chamber 1 are irradiated through a transparent window 4 made of quartz or the like provided on the upper surface of the processing chamber 1, 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.

(Problems to be Solved by the Invention) However, in the conventional ashing device using ultraviolet rays described above, the ashing speed is 50 to 150 nm/m.
Since the process is slow and 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 view of the above-mentioned problems, and it is an object of the present invention to provide an ashing device that has a high ashing speed for photoresist films and is capable of handling single-wafer processing of large-diameter semiconductor wafers without damage. It is.

[Structure of the invention]

(Means for Solving the Problem) When performing ashing by flowing ashing gas onto the surface of the substrate to be processed through a plurality of openings provided in the flat plate part, which are arranged facing the substrate at a predetermined distance from each other, The ashing gas is switched and flows out between at least one of the matching openings.

(Function) The openings provided in the flat plate portion, which are disposed opposite to the substrate to be processed at a predetermined distance and from which the ashing gas flows out, switch the ashing gas between the adjacent openings and flow out. It is possible to perform an ashing process that prevents uneven ashing due to interference in the process, and it is possible to perform single-wafer processing in which each substrate to be processed is processed one by one, which is suitable for large-diameter substrates to be processed.

(Example) Hereinafter, an example in which the method of the present invention is applied to an ashing process in a semiconductor manufacturing process will be described with reference to the drawings.

In FIG. 1, a cylindrical upper chamber 5 with a U-shaped cross section is provided, which is movable up and down by a lifting mechanism (not shown). The upper chamber 5 is provided with a glass flat plate 7 for uniformly discharging the ashing gas. This flat plate 7 has an opening of, for example, a diameter of 0.5 as shown in FIG.
~2. A plurality of opening rows 6a and 6b of Onn order are alternately provided. This flat plate 7 has a larger surface than the substrate to be processed, for example, a semiconductor wafer 16, and one peripheral edge is shaped into a step-like shape.

A gas flow conduit 8a made of, for example, Teflon is connected to each of the opening rows 6a. This pipe 8a is connected to an ozone generator 12 equipped with an oxygen supply source 11 via a switching valve 9a and a gas flow rate regulator 10. On the other hand, a gas flow conduit 8b made of, for example, Teflon is connected to the opening row 6b. This pipe 8b is connected to the gas flow rate regulator 10 via a switching valve 9b.
via an ozone generator 12 with an oxygen supply source 11. That is, the switching valves 9a and 9b enable intermittent control of the ashing gas. Each opening row 6
A slit groove 18 is provided in the gap between the pair of a and 6b, and an exhaust hole 17 is bored in the center of the groove 18.

A lower chamber 13 is provided to engage with the upper chamber 5. Inside the lower chamber 13, disc-shaped mounting tables 15 for mounting the semiconductor wafers 16 are provided on the flat plate 7 at equal intervals around the center. A reaction vessel 22 is provided within the mounting table 15 with a heater 21 for setting the semiconductor wafer 16 to a desired temperature. The temperature of the heater 21 is adjusted by a temperature control mechanism 14 provided outside the container 22. By disposing a temperature sensor (not shown) near the semiconductor wafer 16, the temperature can be automatically set to a constant value. An exhaust hole 23 is provided in the center of the bottom of the reaction vessel 22, and is configured to be exhausted by an exhaust mechanism 17. It is also beneficial to emit ozone from the exhaust gas by decomposing it using a catalyst or the like.

Next, a method of ashing a semiconductor wafer using the above-described ashing apparatus will be described.

The upper chamber 5 is raised by the lifting mechanism, and a substrate to be processed, such as a semiconductor wafer 16, is automatically placed at a predetermined position on the mounting table 15 housed in the lower chamber 13 by a transport mechanism (not shown), such as a hand arm. Transport and place the product.

If the semiconductor wafer 16 is subjected to orientation-flat alignment as necessary, devices with the same characteristics can be manufactured with good reproducibility.

Next, the upper chamber 5 is lowered and connected to the lower chamber 13 to seal the inside of the processing chamber. At this time, the flat plate 7 made of glass, for example, is placed at a distance of, for example, about 0.5 to 20 m from the surface of the semiconductor wafer 16. In this case, the lower chamber 13 may be moved up and down by a lifting mechanism.

Then, a heater installed in the mounting table 15 is controlled by the temperature control mechanism 14, and the semiconductor wafer 16 is
The ashing gas generated by the ozone generator 12 heated to a temperature of about 500° C. and equipped with the oxygen supply source 11 is controlled by the gas flow rate regulator 10 at a flow rate of, for example, 3 to 15 Ω/wi.
A plurality of openings 6a are provided in the flat plate 7, which is adjusted to approximately n and is connected to the upper chamber 5 by the gas flow conduits 8a, 8b via the switching valves 9at9b.

6b, the liquid flows out onto the semiconductor wafer 16 on the mounting table 15. At this time, if the ashing gas flows out from the adjacent opening rows 6a and 6b at the same time, the ashing gas flowing out from the openings 6a and the ashing gas flowing out from the openings 6b will interfere with each other, causing the ashing gas to flow out from the openings 6a and 6b. , the flow rate of the ashing gas becomes Om/see, making it difficult to remove by ashing the film adhering to the surface of the semiconductor wafer 16 directly below this intermediate position. Above opening 6
The outflow of ashing gas from a and 6b is switched so that the ashing gas flows out alternately. This is achieved by the switching valves 9a and 9b always operating in reverse; when the switching valve 9a opens, the switching valve 9b closes at the same time, and the ashing gas flows through the switching valve 9a to the gas flow conduit 8a. The liquid flows out through the opening 6a onto the surface of the semiconductor wafer 16 placed on the mounting table 15. Further, when the switching valve 9b is opened, the switching valve 9a is closed at the same time, and the ashing gas flows out through the switching valve 9b and the gas flow conduit 8b from the opening 6b to the surface of the semiconductor wafer 16. The above switching valves 9a, 9b
The switching may be performed every few seconds or at half the ashing gas outflow time.

Interference of ashing gas between the adjacent openings 6a and 6b is prevented by the method described above. Further, interference of ashing gas between the lines by the openings 6a and 6b formed in a line shape can be avoided, as shown in FIG. Om+
A slit groove 18 of about
By providing an exhaust hole 19 inside and exhausting the air through an exhaust pipe (not shown), uneven ashing of the semiconductor wafer 16 caused by interference of ashing gas between the lines can be prevented.

By the method described above, the ashing gas flows out from the flat plate 7 onto the surface of the semiconductor wafer 16 on the mounting table 15.

After the ashing process, the ashing gas is decomposed by an ozone decomposer (not shown) and exhausted from the exhaust machine VT17.

The ashing process for the semiconductor wafer 16 is thus completed, and the semiconductor wafer 16 is transported to the next step by a transport mechanism (not shown).

In the above embodiment, the switching valves 9a and 9b always operate in reverse to prevent interference on the semiconductor wafer. The mechanism is not limited to the above mechanism.

As described above, according to this embodiment, by providing slit grooves between the lines formed by the linear openings, uneven ashing of the semiconductor wafer 16 caused by interference of ashing gas between the lines can be prevented. .

〔Effect of the invention〕

As explained above, according to the present invention, since the ashing gas is uniformly discharged onto the substrate to be processed, it is possible to perform single-wafer processing in which each substrate to be processed is processed, which is suitable for processing large-diameter substrates to be processed. It becomes possible to do so.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an ashing device in the ashing method of the present invention, Fig. 2 is a block diagram of a flat plate of the ashing gas outlet section of Fig. 1, and Fig. 3 is a block diagram of a conventional ashing device. This figure shows a configuration diagram of the device. 2.16... Semiconductor wafer, 6a, 6b... Opening,
7... Flat plate, 8a, 8b... Gas flow conduit. 9a, 9b...Switching valve, 18...Slit groove, 19...Exhaust hole. Patent applicant Tokyo Electron Ltd. Figure 1

Claims (1)

[Claims] When ashing gas is discharged onto the surface of the substrate to be processed through a plurality of openings provided in the flat plate portion, which are arranged facing each other at a predetermined distance from the substrate to be processed, between at least one of the adjacent openings. An ashing method characterized in that the ashing gas is switched and flows out.