JPH10163178A - Method of removing resist - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove the ashing residuum of resist exposed to dry etching by controlling the oxidative reaction by the action of ozone and ozone and ultraviolet rays. SOLUTION: A semiconductor substrate 1 is put on a stage 3 within a treatment chamber 2. A heater 4 for heating is built in the stage 3, and the surface temperature of the stage 32 is controlled by a thermocouple 5 and a temperature adjuster 6. A quartz board 8 is installed opposite to the stage 3, and a nozzle 9 for ozone supply is attached to the quart board 8. There is an ultraviolet ray lamp 10 on the quart board 8, and the ultraviolet rays can be applied optionally to the semiconductor substrate 1. For the ultraviolet ray lamp 10, a low- pressure mercury lamp is used. The ozone is is produced and supplied, with oxygen gas as material, by an ozone generator 11. The quantity of generated ozone is measured by an ozone densitometer 12, and the signal is feedback to an ozone generator 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for removing a resist.

[0002]

2. Description of the Related Art The removal of organic substances adhered to the surface of an individual and the cleaning of the surface of an object to be processed are performed by manufacturing semiconductor devices, optical components,
It is used for cleaning glass for liquid crystal. For example, in a manufacturing process of a semiconductor device, a resist is used as a mask for ion implantation or dry etching. The resist is removed after performing the above-described desired processing on the semiconductor substrate.

Conventionally, as one of the resist removing methods, a method of performing ashing by the action of ozone or the action of ozone and ultraviolet rays has been used.

An example of this type of apparatus is described in Hitachi Review, Vol. 73, No. 9, pp. 37-42 (1991-1-9).

[0005]

Although the above-mentioned prior art resist ashing method can easily remove untreated resist, the removal of the resist exposed to a dry etching process or the like requires removing the substrate surface after ashing. There is a problem of leaving a residue.

For example, in the case where a contact hole is formed by dry-etching an interlayer insulating film such as a multi-layer Al-based wiring in a semiconductor device, ashing remains after etching to leave a residue around the contact hole. Removal of this residue makes it impossible to perform strong cleaning using acids because the wiring is exposed. Therefore, removal by ashing is indispensable.

[0007] If the residue remains, the reliability of the semiconductor device is remarkably deteriorated, for example, the wiring of the contact portion cannot be formed normally in the next step, causing disconnection.

This residue is considered to be caused by the interlayer insulating film and the Al-based wiring material adhering to the resist which is a mask during the etching process due to a sputtering phenomenon or the like during the etching process and being oxidized and deteriorated during the ashing process.

It is an object of the present invention to provide a method for removing an organic substance in which ashing residue of a resist exposed to a dry etching process is improved.

[0010]

The removal of organic substances by ozone or ozone and ultraviolet rays decomposes and volatilizes organic substances by the strong oxidizing power of ozone. At this time, the temperature of the object is raised to about 300 ° C. to increase the speed of the oxidation reaction, thereby promoting the decomposition of organic substances.

It is considered that the above-mentioned residue is a residue of the etching product adhering to the resist surface oxidized during the oxidation reaction. From this, if the oxidation reaction by the action of ozone or ozone and ultraviolet rays is controlled, the oxidation of the etching product can be suppressed and the residue can be reduced.

There are two ways to control the rate of the oxidation reaction. That is, a method of controlling the temperature of the object to be processed and a method of controlling the amount of ozone supplied to the surface of the object to be processed. In the former case, the rate of the oxidation reaction is limited by lowering the temperature of the object. Thereby, oxidation of the etching product is suppressed, and the etching product can be removed.
In the latter case, on the other hand, the rate of the oxidation reaction is limited by reducing the amount of ozone, which is an oxidizing agent, so that the oxidation of the etching product is suppressed and the etching product can be removed.

For example, in the ashing process after the etching of the interlayer insulating film of the Al-based wiring, the residue can be reduced by ashing at a substrate temperature of 280 ° C. or lower. A similar effect can be achieved by setting the ozone amount to 80 g / Nm ³ or less at a substrate temperature of 300 ° C.

Al or Si is used as an Al-based wiring material, and Ti or the like is used when a barrier layer is provided. The interlayer insulating film is S
The oxide film of i is used. These materials adhere to the side walls and the surface of the resist due to a sputtering phenomenon or the like during etching. At this time, it is considered that these elements react with the resist, the etching gas, and the like, and are attached in an organic compound state. When exposed to a high-temperature ozone atmosphere in this state, the metal element becomes an oxide state due to the progress of a strong oxidation reaction and remains on the substrate surface. Al, Ti, and the like are relatively easily oxidized among the metal elements, as can be seen from the magnitude of the enthalpy of oxide formation. However, by lowering the temperature and performing ashing to adjust the oxidation reaction rate, the etching product in an organic compound state is lifted off in a molecular group state by a thermal decomposition reaction or the like. Thereby, ashing residue is reduced. On the other hand, when the amount of ozone is controlled, no residue remains because the amount of ozone is limited and the thermal decomposition reaction precedes.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows an example of an ashing apparatus used in the present invention. The present apparatus is an apparatus for performing ashing by flowing ozone to the surface of a processing object and heating the processing object. An example in which an ashing process is performed after etching an interlayer insulating film of an Al-based wiring in a semiconductor device using the present device will be described.

On the surface of the semiconductor substrate 1, which is the object to be processed, there is a resist used as a mask for dry etching. This semiconductor substrate 1 is placed on the stage 3 in the processing chamber 2. A heating heater 4 is built in the stage 3, and the surface temperature of the stage is 280 ° C. by a thermocouple 5 and a temperature controller 6.
Is controlled by The stage 3 has a mechanism 7 for vacuum-sucking the semiconductor substrate 1. The semiconductor substrate 1 is placed on the stage 3 and vacuum-adsorbed, so that the semiconductor substrate 1 is controlled at the same temperature as the stage 3.

A quartz plate 8 is provided to face the stage 3, and the quartz plate 8 is provided with an ozone supply nozzle 9. An ultraviolet lamp 10 is provided on the quartz plate 8 so that the semiconductor substrate 1 can be arbitrarily irradiated with ultraviolet light. As the ultraviolet lamp 10, a low-pressure mercury lamp was used. Ozone is generated and supplied by an ozone generator 11 using oxygen gas as a raw material. The ozone generation amount is measured by the ozone concentration meter 12 and fed back to the ozone generator 11 to be controlled.

The inside of the processing chamber 2 is evacuated by a duct 13 and excess ozone and ashing reactive products are discharged out of the processing chamber 2.

The stage 2 on which the semiconductor substrate 1 is mounted rises toward the quartz plate 8 placed opposite thereto, and rotates while controlling the gap between the semiconductor substrate 1 and the quartz plate 8 to 0.3 mm. afterwards,
Ozone is supplied and the ashing process is started.

A contact hole is formed in the interlayer insulating film between the Al-based wirings by dry etching, and the number of residues when the semiconductor substrate is ashed is measured by a scanning electron microscope (SEM).
FIG. 2 shows the results of counting by using. The vertical axis indicates the number of residues, and the number of residues is the number per contact hole and the size is 0.01 μm or more. The horizontal axis shows the semiconductor substrate temperature during ashing. Open circles indicate that ultraviolet irradiation was performed, and black circles indicate that no ultraviolet irradiation was performed. As is clear from the figure, when the temperature of the semiconductor substrate is 280 ° C. or lower, the number of residues decreases, and when the temperature is 270 or lower, no residue is observed.

FIG. 3 similarly shows the relationship between the ozone concentration and the number of residues. The vertical axis is the number of residues, and the horizontal axis is the raw material oxygen flow rate 20 L / mi.
The amount of ozone generated in n is shown. 80g /
It decreased from Nm ³ or less, not seen at all in 70g / Nm ³ or less.

[0023]

According to the present invention, the resist exposed to the dry etching treatment can be removed without leaving any residue by the action of ozone or ozone and ultraviolet rays. This also significantly improves the reliability of the semiconductor device.

[Brief description of the drawings]

FIG. 1 is an explanatory view of an organic matter removing device embodying the present invention.

FIG. 2 is a measurement diagram showing a correlation between the number of residues and a semiconductor substrate temperature according to one embodiment of the present invention.

FIG. 3 is a measurement diagram showing the correlation between the number of residues and the ozone concentration according to one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... Processing room, 3 ... Stage, 4 ... Heater, 5 ... Thermocouple, 6 ... Temperature controller, 7 ... Vacuum suction mechanism, 8 ...
Quartz plate, 9 ozone supply nozzle, 10 ultraviolet lamp,
11 ozone generator, 12 ozone concentration meter, 13 duct, 14 ozone pipe.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Kazuo Nojiri, 882 Ma, Hitachinaka-shi, Ibaraki, Japan Measurement Instruments Division, Hitachi, Ltd. (72) Shunji Sasabe 5-2-1, Josuihoncho, Kodaira-shi, Tokyo No.In the semiconductor division of Hitachi, Ltd.

Claims (5)

[Claims] An ashing method for stripping a resist exposed to a dry etching treatment by the action of ozone or ozone and ultraviolet rays, wherein the ashing is performed by controlling the temperature of an object to be processed to an arbitrary temperature or lower. How to remove resist. 2. A method for removing a resist according to claim 1, wherein said dry etching is etching of an interlayer insulating film between Al-based wirings in a semiconductor device manufacturing process. 3. The method according to claim 1, wherein the temperature of the object is controlled at 280 ° C. or lower. 4. A method for removing a resist according to claim 1, wherein the amount of ozone supplied to the surface of the object is controlled to an arbitrary amount and ashing is performed. 5. The method according to claim 4, wherein the amount of ozone supplied to the surface of the object is controlled to 4 vol% or less of the raw material gas.