JPH06244098A - Resist removal method and resist removal device - Google Patents

Abstract

PURPOSE:To remove resist uniformly at a high speed without damaging an element by using an ozone ashing method. CONSTITUTION:In a resist removal method wherein ozone gas is brought into contact with a resist 26 formed on a substrate 24 and ultraviolet ray is applied to ozone gas, a nozzle 28 for discharging ozone gas is provided near a substrate surface and the substrate is heated, and ozone gas is jetted to the resist from the nozzle and the ozone gas is irradiated with ultraviolet ray. Thereby, the resist can be removed uniformly much more rapidly than by a conventional ozone ashing method without damaging an element.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to removal of resist in a lithography technique used for manufacturing semiconductors, thin film sensors and the like.

[0002]

2. Description of the Related Art A fine and very precise technique is required for manufacturing a semiconductor or a thin film sensor.
Among them, lithography technology is an important factor that determines product performance, yield, quality and the like. The lithographic technique comprises steps such as resist application, masking, exposure, development, etching and resist removal. Among them, there is a method of removing the resist by using an oxidizing agent or a stripping solution for removing the resist, but an ashing method (ashing treatment) by oxygen gas plasma has a high processing speed and is widely used at present.

[0003]

As described above, the ashing treatment by the oxygen gas plasma is widely used because it enables a high-speed treatment, but the damage to the element by the charged particles is large, and the ashing treatment is difficult. There was a case where it was fatally damaged for high integration and miniaturization. Therefore, a resist removing method that causes less damage to the element, particularly an ozone ashing method that uses ozone and ultraviolet rays has been studied.
In this ozone ashing method, a substrate on which a resist to be removed is formed is placed in a reaction vessel, the substrate is heated, and ozone gas is injected into the vessel from the side wall of the reaction vessel to create an ozone gas atmosphere that flows in parallel with the substrate. The substrate surface is brought into contact with the inside, and ultraviolet rays are irradiated from above. By irradiating ozone with ultraviolet rays, radical oxygen (O ^* ) is generated as in the following formula. O ₃ → O ^* + O ₂ ... And, since the resist material is usually composed of various hydrocarbons, the decomposition reaction (ashing reaction) shown in the following formula is caused by the reaction of radical oxygen and hydrocarbon. It occurs and the hydrocarbon resist is ashed and removed. _{C n H m + (2n +} m / 2) O 3 → nCO 2 + m / 2H 2 O + (2n + m / 2) O 2 ···

However, the ozone ashing method in which the ozone gas is supplied in a laminar flow system and the element to be treated is reacted with the radical oxygen in the ozone gas atmosphere, does not damage the element, but the removal rate of the resist is extremely slow. The current situation is that it has not been put to practical use. Generally, the ashing rate by oxygen gas plasma is 1
Although it is μm / min, the processing speed by the ozone ashing method is very low at 0.1 μm / min. Since the film thickness of the VLSI resist is usually 2 to 3 μm, the treatment time by oxygen plasma is 2 to 3 minutes, but the ozone ashing method also requires 20 to 30 minutes. The long time required to remove the resist increases the production cost of the product.

This slow removal rate is due to radical oxygen (O
^* ) Is very unstable, so the life in the active state is very short, and the radical oxygen generated from ozone supplied into the container reaches and contacts the resist, and the reaction efficiency with the resist is low. It is considered that this is because the supplied ozone is not used effectively for the ashing reaction and thus the utilization efficiency is low. Further, if ozone is supplied in a laminar flow system, a difference in ozone concentration occurs between the ozone inflow side and the downstream side of the substrate, and uneven ashing of the resist causes uneven resist removal.

The present invention has been made to solve the above problems, and is a method of removing a resist using an ozone ashing method, which removes the resist uniformly at high speed without damaging the device. It is a thing.

[0007]

The resist removing method of the present invention is a resist removing method in which an ozone gas is brought into contact with a resist formed on a substrate and the ozone gas is irradiated with ultraviolet rays. Is provided in the vicinity of the above to heat the substrate, spray ozone gas onto the resist from the nozzle, and irradiate the sprayed ozone gas with ultraviolet rays.

A resist removing method according to a second aspect is the resist removing method according to the first aspect, characterized in that oxygen gas existing in the peripheral portion of the substrate is removed.

The resist removing method according to claim 3 is the resist removing method according to claim 1 or 2, wherein nitrogen gas is used as a carrier gas to blow ozone gas.

According to a fourth aspect of the present invention, there is provided a resist removing apparatus, in which a substrate having a resist formed thereon is installed, an ozone generator for supplying ozone to the container, and ozone from the ozone generator into the container. An ozone supply device including a supply pipe for guiding and a nozzle provided at the position near the substrate and having a tip end facing the substrate and an ultraviolet ray for irradiating the ozone gas blown from the nozzle with ultraviolet rays. It has a lamp and a heating device for heating the substrate.

A resist removing apparatus according to a fifth aspect is the resist removing apparatus according to the fourth aspect, in which the nozzle has an elongated shape in a direction parallel to the substrate and is formed at the tip of the nozzle along the longitudinal direction. Ozone gas is discharged from the formed slits, and at least one of the substrate and the nozzle moves relatively to the other so that ozone is uniformly sprayed on the resist.

[0012]

According to the present invention, ozone is sprayed onto the resist from the tip of a nozzle provided close to the resist to be removed, and the sprayed ozone is irradiated with ultraviolet rays to ash and remove the resist. Since the ashing method is used, radical oxygen is generated by irradiating the ozone with ultraviolet rays only in the vicinity of the resist without damaging the element subjected to the resist removal treatment,
Even if the life of the radical oxygen is short, the radical oxygen and the resist efficiently cause an ashing reaction, and the resist can be removed in a short time with high ozone utilization efficiency. Further, by spraying ozone together with a carrier gas directly onto the resist at a high flow rate, it is possible to reduce the mixing of oxygen in the reaction between ozone and the resist, so that the ashing reaction is promoted and the resist removal rate is improved. Furthermore, by removing oxygen generated by the ashing reaction, the ashing reaction is promoted, and the removal rate of the resist is improved.

Further, according to the resist removing apparatus of the present invention, at least one of the substrate and the nozzle moves relatively to the other, and the ozone discharged from the long slit of the nozzle is evenly sprayed directly on the resist. Therefore, the resist on the substrate is uniformly removed.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. [Embodiment 1] FIGS. 1 and 2 show a resist removing apparatus of Embodiment 1, FIG. 1 (a) is a plan view and FIG. 1 (b) is a side view. In the resist removing apparatus 10 of this embodiment, a disk-shaped substrate 24 for removing the resist film 26 is applied.
Is placed on the substrate holder 22 and installed in the container 12. The substrate holder 22 is a hot plate 1 which is a heating device.
Fixed on 8. The container 12 is provided with an ozone supply device including an ozone generator 32, a supply pipe 30, and a nozzle 28. The ozone generator 32 generates ozone from oxygen, and has an additional function such as sending ozone gas together with a carrier gas to the supply pipe 30 as necessary. The supply pipe 30 guides the ozone gas generated by the ozone generator 32 to the vicinity of the substrate 24, and has a nozzle 28 at the tip.
Are formed. The nozzle 28 may be formed integrally with the supply pipe 30 or may be a separate body. The nozzle 28 is elongated in a direction parallel to the surface of the substrate 24, and its length is the same as the radius of the disk-shaped substrate 24 and is arranged along the radial direction of the substrate 24.
Further, the tip of the nozzle 28 is arranged so as to be located very close to the surface of the substrate 24, and a slit 40 which is an ozone gas discharge port as shown in FIG. 2 is formed at the tip of the nozzle 28. The nozzle 28 is arranged so as to face 24. The tip of the nozzle 28 and the substrate 24
The appropriate distance is 1.5-2 mm.

A cooling mechanism is formed in the supply pipe 30 and the nozzle 28 of this embodiment. As shown in FIG. 2, the cooling mechanism has a refrigerant circulation path 43 around the ozone gas supply path 41.
Are formed and configured. The refrigerant circulating path 43 is a passage through which the refrigerant cooled to a predetermined temperature flows. The refrigerant A flows from the refrigerant feed pump (not shown) having a cooling function in the outward path 42 toward the tip of the nozzle 28, and then in the return path 44. The ozone gas flowing in the supply path 41 is cooled by flowing again into the refrigerant supply pump and circulating. As the refrigerant A, a liquid such as water or freon or a gas such as He or CO ₂ can be applied. Although this cooling mechanism is not always necessary, it is preferable that the ozone gas before being blown out from the nozzle 28 is cooled.

The hot plate 18 heats the substrate 24. The thermocouple 34 connected to the substrate holder 22 detects the temperature of the substrate 24, and the obtained temperature data is fed back to the hot plate 18 so that the hot plate 18 is hot. By controlling the plate 18, the temperature of the substrate 24 is maintained at a predetermined temperature.
A scavenging pipe 36 is provided in the resist removing apparatus 10, and the tip of the scavenging pipe 36 is set at a position near the substrate 24. Further, an exhaust pipe 38 is provided above the container 12. An exhaust pump (not shown) is provided in the exhaust pipe 38 to exhaust the gas in the container 12 to the outside. The container 12 is
After the substrate 24 to be processed is placed, the lid 14 is placed to seal the substrate. An ultraviolet lamp 16 is provided above the lid 14. Ultraviolet rays emitted by the ultraviolet lamp are nozzle 2
At least the lower part of the ultraviolet lamp 16 of the lid 14 is made of quartz glass that transmits ultraviolet rays so that the ozone blown from the lamp 8 can be reached.

In order to remove the resist 26 formed on the substrate 24 in the resist removing apparatus 10 having the above structure, first, the substrate 24 to be processed is placed on the substrate holder 24, and the substrate 24 is heated by the hot plate 18 which is a heating device. To heat. After the substrate 24 is heated to a predetermined temperature and becomes stable, ozone gas is generated by the ozone generator 32 and directly sprayed from the nozzle 28 onto the resist 26 on the substrate 24. On this occasion,
It is preferable that ozone is sprayed at a high flow rate using nitrogen gas as a carrier gas. That is, the nozzle 28
From the above, the mixed gas of ozone gas and nitrogen gas is discharged vigorously. It is desirable to perform deoxidation treatment so that this mixed gas contains as little oxygen as possible.
Then, the ozone-containing gas is supplied from the tip of the nozzle 28 to the substrate 2
The ultraviolet rays are radiated to the ozone from the ultraviolet lamp 16 while being sprayed on the surface 4. Thus, the resist 26 is efficiently contacted by radical oxygen generated by irradiation of ultraviolet rays,
The resist is incinerated. Carbon dioxide, water vapor, and oxygen generated by the ashing process are exhausted to the outside of the container 12 through the exhaust pipe 38.

At the time of this ashing process, nitrogen gas is supplied from the scavenging pipe 36 into the container 12. The supplied nitrogen gas replaces the oxygen gas existing near the surface of the substrate to remove the oxygen gas and reduce the oxygen gas concentration in the ashing reaction section.
That is, the oxygen gas is sequentially exhausted from the exhaust pipe 38 and the nitrogen gas is supplied from the scavenging pipe 36, so that the container 1
The nitrogen concentration in 2 is increased and the oxygen concentration is decreased. As is clear from the above formula, by reducing the oxygen gas concentration in the reaction system, the ashing reaction is more likely to occur, the ashing efficiency is increased, and the processing speed is improved. In addition to using the scavenging pipe 36, by disposing an oxygen adsorbent near the substrate, oxygen generated by the ashing reaction can be removed from the reaction system to promote the ashing reaction. In addition, since nitrogen gas is used as a carrier gas and oxygen gas is not mixed in the mixed gas, the oxygen concentration in the reaction system of ozone and resist can be reduced, so that the ashing reaction is also accelerated and the ashing is performed. Increased efficiency and increased processing speed.

During the ashing process, the hot plate 1
8 is rotated about the rotating shaft 20 by the driving force of a motor (not shown). The substrate 24 to be processed is rotated by rotating the hot plate 18, and the ozone gas is transferred to the resist 2
It is sprayed evenly and evenly on No. 6. By uniformly spraying the ozone gas onto the resist 26, it is possible to perform a uniform resist removal process without causing unevenness in the ashing process.

According to the resist removing method and the removing apparatus 10 of the present embodiment, the ozone gas is directly sprayed onto the resist 26 at a high flow rate from the nozzle 28 located in the immediate vicinity of the resist 26. Since ozone is shielded from ultraviolet rays, the ozone is irradiated with ultraviolet rays only after being blown out from the nozzle 28, that is, in the immediate vicinity of the resist, and therefore radical oxygen is generated only in the immediate vicinity of the resist. Therefore, most of the generated radical oxygen is allowed to undergo an ashing reaction with the resist without reaching the end of its life, the radical oxygen is reacted without waste, and the ozone utilization efficiency is increased. Therefore, the resist removal processing speed can be increased. Further, since the method of the present invention is based on the ozone ashing method, unlike the plasma ashing method, it does not cause damage to the device, and can be used for manufacturing a highly integrated, miniaturized integrated circuit or the like. Since it is suitable and the processing speed is high, it does not increase the production cost.

Further, the radical oxygen production reaction from ozone is easily caused by heating in addition to ultraviolet irradiation, but as in this embodiment, the supply pipe 30 and the nozzle 2 are used.
By cooling 8, the generation of radical oxygen in the supply pipe 30 and the nozzle 28 can be suppressed, and the radical generation reaction that cannot be used for the ashing reaction can be suppressed. Therefore, the utilization efficiency of the supplied ozone is improved, and the processing speed can be further increased.

"Example of resist removal" As shown below, (1)
A sample was prepared, (2) ozone ashing according to this example was performed, and (3) an ashing rate measurement test at that time was performed. (1) A resist (positive resist (manufactured by Nagase Denshi Kagaku)) was spin-coated on a silicon wafer and prebaked at 95 ° C. for 30 minutes. Next, using a mask having a width of 1 mm, irradiation with a high pressure mercury lamp (275 W) was performed for 40 seconds to expose the photosensitive agent in the resist. Then, develop with a developing solution (Nagase developing solution 809) for 40 seconds, wash with water, and then at 30 ° C. for 30
Baking was performed for a minute, and this was used as a sample. (2) Oxygen gas was supplied to the ozone generator 32 at a predetermined flow rate, and the generated ozone was concentrated and collected in a silica gel adsorption column cooled to -70 ° C. After a lapse of a predetermined time, the temperature of the silica gel adsorption column was set to −20 ° C., and nitrogen gas was supplied at 60 cm ³ / min to prepare an ozone-containing gas. The oxygen in the silica gel adsorption column was removed at -70 ° C. This ozone-nitrogen mixed gas is used at each preset temperature (150 ° C, 20 ° C).
The sample was heated to 0 ° C. and 250 ° C.) and sprayed onto a sample placed on a stable substrate holder 22 to ash the resist. The mixed gas was sprayed for 0.5 to 10 minutes so that the ozone concentration was 3 to 5%. The UV lamp is a 100W low-pressure mercury lamp, and the distance from the substrate is 1
It was placed at the position of 00 mm. At the same time, 100 ml of nitrogen gas was supplied from the scavenging pipe 36 per minute. (3) The ashing rate was calculated by measuring the film thickness of the resist film before and after the ashing process. In the test, nitrogen gas was used as a carrier gas, oxygen gas was used, and ozone was supplied by a conventional laminar flow method as a comparative example (ozone concentration: 8
%) Was used (PES-730 manufactured by Oak Manufacturing Co., Ltd.) was measured. The test results are shown in FIG.

From FIG. 5, according to the method of the present invention in which ozone is directly sprayed onto the substrate together with the carrier gas, the processing speed can be remarkably increased as compared with the conventional laminar flow method, especially when the temperature is high. Recognize. In the case of LSI devices,
In order to protect the device, it is desirable to keep the substrate heating temperature below 250 ° C, but from Fig. 5, at the heating temperature of 250 ° C, the ashing rate is about 0.6μm / min in the conventional laminar flow method, and it is practically used. Although the level has not been reached, the method of the present invention has achieved a ashing rate of 4 to 7 times that which is sufficiently practical. Further, it can be seen that the processing speed is faster when nitrogen gas is used as the carrier gas than when oxygen gas is used. The higher the temperature, the higher the processing speed, but this may be because the ashing reaction of the resist may be controlled by the direct oxidation reaction of the polymer by radical oxygen and the accompanying evaporation of polymer fragments. In the low temperature region, it is considered that the ashing rate did not improve because the evaporation of the polymer fragment with the reduced molecular weight was suppressed.

[Embodiment 2] Another embodiment of the resist removing apparatus of the present invention will be described with reference to FIG. Since the schematic structure is the same as that of the resist removing apparatus of the first embodiment, only different points will be described. In the present invention, the ozone gas is required to be discharged near the substrate and sprayed uniformly on the substrate. However, as in the first embodiment, the substrate does not move with respect to the nozzle, but with respect to the fixed substrate. It does not matter if the nozzle moves. That is, in the resist removing apparatus according to the second embodiment, the main part of which is shown in FIG. 3, the supply pipe 30 is connected to the end of the nozzle 46, and the rotating shaft 48 capable of generating the rotational driving force is provided at the connecting portion. Therefore, the nozzle 46 rotates around the rotation shaft 48. Since the rotation shaft 48 is located above the center of the substrate 24 on the disk, even if the substrate 24 does not rotate, the ozone discharged from the nozzle 46 that rotates about the center of the substrate 24 is uniform and even. Sprayed on 24.

It is sufficient that the nozzle and the substrate relatively move so that the ozone gas discharged from the nozzle is uniformly sprayed onto the substrate. In the arrangement shown in FIG. 3, the nozzle 46 and the substrate 24 are in the same direction and at the same angular velocity. Other than the movement in which the relative speed becomes zero, that is, the nozzle 46 and the substrate 24
The and may move in opposite directions or in the same direction but at different angular velocities.

[Embodiment 3] Further, the movement of the substrate or the nozzle is not limited to the rotational movement, and as shown in FIG. 4, the nozzle 52 having a width larger than the diameter of the substrate reciprocates on the fixed substrate 24. It may have a repeating structure.
At this time, the supply pipe 50 repeats the expansion and contraction movement. On the contrary, the substrate 24 may repeat the reciprocating motion below the fixed nozzle 52.

Even if either the nozzle 52 or the substrate 24 moves as described above or both of them move relatively, the ozone gas discharged from the slit formed at the tip of the nozzle is It is necessary to be evenly sprayed on the resist that is formed and is to be removed.

[0028]

According to the resist removing method of the present invention, in the resist removing method of contacting the ozone gas with the resist formed on the substrate and irradiating the ozone gas with ultraviolet rays, the nozzle for ejecting the ozone gas is near the substrate surface. And heating the substrate, spraying ozone gas onto the resist from the nozzle, and irradiating the sprayed ozone gas with ultraviolet rays. A resist removing method according to a second aspect is the resist removing method according to the first aspect, characterized in that oxygen gas existing in a peripheral portion of the substrate is removed. A third aspect of the resist removing method according to the first or second aspect is that nitrogen gas is used as a carrier gas to blow ozone gas. The resist removing apparatus according to claim 4, wherein a container in which the substrate on which the resist is formed is installed, an ozone generator for feeding ozone to the container, and a supply pipe for guiding ozone from the ozone generator into the container. An ozone supply device provided with a nozzle provided at the supply pipe and having a tip near the substrate and facing the substrate, and an ultraviolet lamp for irradiating the ozone gas blown from the nozzle with ultraviolet rays. And a heating device for heating the substrate. A resist removing apparatus according to a fifth aspect is the resist removing apparatus according to the fourth aspect, wherein the nozzle has an elongated shape in a direction parallel to the substrate, and a slit formed along the longitudinal direction at the tip of the nozzle. While ozone gas is discharged from the substrate, at least one of the substrate and the nozzle moves relatively to the other, and ozone is evenly sprayed on the resist.

According to the present invention, the ozone gas is guided to the vicinity of the resist where the ozone gas is removed as much as possible so that the ozone decomposition reaction of generating radical oxygen from ozone does not occur, and the radical oxygen is irradiated by irradiating the ultraviolet light in the vicinity of the resist. Since the radical oxygen and the resist are reacted with each other by generating, the use efficiency of ozone can be improved without wasteful generation of radical oxygen. Therefore, the resist removal rate can be increased. Therefore, the processing time can be shortened and the production cost can be reduced.

By blowing ozone at a high flow rate using a carrier gas containing nitrogen gas, it is possible to suppress the mixing of oxygen in the reaction between ozone and the resist, and to reduce the oxygen concentration in the ashing reaction system. By lowering the ashing reaction, the resist removal rate is improved. Furthermore, by removing oxygen generated during the ashing reaction, the ashing reaction is also promoted and the resist removal rate is improved. Also,
With the resist removing apparatus of the present invention, ozone is evenly blown onto the resist through the long slits that move relatively to the substrate, so that the resist is uniformly and evenly removed.

As described above, according to the present invention, the ozone ashing method can remove the resist without damaging the element and at a much higher speed and more uniformly than the conventional ozone ashing method. Can be achieved. In particular, it is suitable for manufacturing highly integrated and fine integrated circuits.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a resist removing apparatus according to a first embodiment,
1A is a plan view and FIG. 1B is a side view.

FIG. 2 is a side sectional view showing a nozzle of the present embodiment.

FIG. 3 is a main part plan view for explaining a resist removing apparatus according to a second embodiment.

FIG. 4 is a plan view of a main part for explaining a resist removing apparatus according to a third embodiment.

FIG. 5 is a graph showing the relationship between the substrate heating temperature and the ashing rate.

[Explanation of symbols]

 10 Resist Removal Device 12 Container 16 Ultraviolet Lamp 18 Hot Plate 20 Rotating Shaft 22 Substrate Holder 24 Substrate 26 Resist 28 Nozzle 30 Supply Pipe 32 Ozone Generator 36 Scavenging Pipe 38 Exhaust Pipe 40 Slit 46 Nozzle 50 Supply Pipe 52 Nozzle

Claims (5)

[Claims] 1. A method of removing a resist in which ozone gas is brought into contact with a resist formed on a substrate and the ozone gas is irradiated with ultraviolet rays, a nozzle for discharging the ozone gas is provided near the surface of the substrate to heat the substrate, and the ozone gas is discharged. Is sprayed onto the resist from the nozzle and the ozone gas blown out is irradiated with ultraviolet rays. 2. The resist removing method according to claim 1, wherein oxygen gas existing in the peripheral portion of the substrate is removed. 3. The resist removing method according to claim 1 or 2, wherein nitrogen gas is used as a carrier gas to spray ozone gas. 4. A container in which a substrate on which a resist is formed is installed, an ozone generator for supplying ozone to the container, a supply pipe for guiding ozone from the ozone generator into the container, and the supply pipe. An ozone supply device provided with a nozzle provided at a position near the substrate at a position near the substrate and facing the substrate, an ultraviolet lamp for irradiating ozone gas blown from the nozzle with ultraviolet rays, and heating for heating the substrate An apparatus for removing a resist. 5. The resist removing apparatus according to claim 4, wherein the nozzle has an elongated shape in a direction parallel to the substrate,
Ozone gas is discharged from a slit formed at the tip of the nozzle along its longitudinal direction, and at least one of the substrate and the nozzle moves relatively to the other so that ozone is evenly sprayed on the resist. Resist removal device.