KR960008894B1 - Ashing method - Google Patents

Abstract

None.

Description

Ashing method

1 is an explanatory diagram showing a schematic configuration of an entire ashing apparatus of a semiconductor wafer of a first embodiment to which the present invention is applied.

2 is a plan view of a semiconductor wafer supply apparatus according to the present invention.

3 is an explanatory diagram showing a method for protecting and supporting a semiconductor wafer by a handling arm in the present invention.

4 is a cross-sectional view showing an internal structure of a processing chamber according to the present invention.

5 is a characteristic diagram showing the relationship between the decomposition half-life of ozone and temperature according to the present invention.

FIG. 6A is an explanatory diagram showing a relationship between a nozzle and an insulating plate that emit ashing gas in the present invention; FIG.

6b is a schematic enlarged configuration diagram of a diffusion plate according to the present invention.

7 to 13 are characteristic diagrams showing the relationship between the ashing ratio and the radial position of the wafer in the present invention.

14 is a characteristic diagram showing the relationship between the ashing residue amount and the radial position of the wafer in the present invention.

15 and 16 are characteristic diagrams showing the relationship between the ashing ratio and the radial position of the wafer in the present invention.

FIG. 17 is an explanatory diagram showing a configuration of an ashing device having a plurality of nozzles and a plurality of ashing gases emitting gas in the present invention. FIG.

18 to 20 are explanatory diagrams showing an example of the configuration of a gas outlet of a nozzle to be used as the ashing apparatus shown in FIG.

21 is a characteristic diagram showing the relationship between the ashing ratio and the distance from the wafer center in the present invention.

22 is a characteristic diagram showing the relationship between ashing ratio and dinitrogen monoxide flow rate in the present invention.

* Explanation of symbols for main parts of the drawings

10: process chamber 10a: upper chamber

10b: lower chamber 10a1: opening edge portion

10a2: cover part 10a3: cooling chamber

11: semiconductor wafer 10b1: opening edge portion

12: mounted stand 13: temperature control device

14: heater 15: lifting device

16: exhaust path 17: exhaust device

18: end point detection device 19: cooling device

20: supply portion of ashing gas 20a: oxygen supply source

20b: ozone generator 20c: air purifier

20d: gas flow regulator 20d1... 20d3: gas flow regulator

20e: dinitrogen monoxide source 20f: nitrogen oxide gas generator

20g: gas flow regulator 21: drive unit

22: alarm unit 25: wafer supply apparatus

25a: loader part 25b: unloader part

25a1: Supply part 25a2: Positioning part

25a3: guide 25a4: conveying belt

25a5, 25a6: basic frame 25a7: handling arm

25b1: momentary mounting portion 25b2: handling arm

25b3: Wafer return part 25b4: Transfer belt

26: nozzle 26a which blows out gas. 26e: Nozzle

26f: small hole 26a6... 26a8: opening

26a1... 26a3: Slit 27: Outlet

28: insulation plate 29: pin

30: diffusion plate 31: lifting pin

32: Seal ring L: gap between semiconductor wafer surface and insulation plate

O ₃ : ozone

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ashing method for ashing a photoresist film or the like deposited on a semiconductor wafer using ozone.

As is well known, the formation of a fine pattern of a semiconductor integrated circuit generally uses a photoresist film of an organic polymer formed by exposure light and development as a mask to cover the bottom film formed on the semiconductor wafer. Work is done.

After the etching process, the photoresist film used as this mask needs to be removed from the surface of the semiconductor wafer.

In this case, an ashing process is performed as an example of the process of removing the photoresist film. This ashing treatment is also used for removing resists, cleaning silicon wafers and masks, removing ink, removing solvent residues, and also suitable for dry cleaning of semiconductor processes. .

As an ashing apparatus for removing the photoresist film, an oxygen plasma is generally used.

An apparatus for ashing a photoresist film using an oxygen plasma includes placing a semiconductor wafer with a photoresist film in a processing chamber, and converting oxygen gas introduced into the processing chamber into a plasma by a high frequency electric field to generate radicals of oxygen atoms. ) Oxidizes the photoresist film, which is an organic material, and decomposes and removes carbon dioxide, carbon monoxide and water.

Therefore, in the ashing apparatus using an oxygen plasma, since the ion wafer and the electron accelerated by the electric field which exist in a plasma are irradiated to a semiconductor wafer, there existed a problem that a semiconductor wafer was damaged.

In addition, there has been an ashing apparatus which generates radicals of oxygen atoms by irradiating ultraviolet rays and performs ashing treatment as a batch treatment.

Such an ashing apparatus using ultraviolet rays does not cause damage to the semiconductor wafer by plasma, but requires a lot of time due to the slow treatment at an ashing rate of 50 to 150 nm / minute.

For this reason, for example, there was a problem in that it is not possible to process the semiconductor wafer one by one, which is suitable for the processing of the semiconductor wafer having a large diameter.

In addition, the applicant has developed an ashing technique capable of performing good ashing without irradiating ultraviolet rays.

As for this technique, there is disclosed, for example, in US Patent 4341592.

That is, the summary of the contents is that the diffusion plate having a plurality of openings is brought close to the semiconductor wafer in order to diffuse the ashing gas onto the semiconductor wafer and flow the ashing gas onto the semiconductor wafer through the diffusion plate to perform the ashing process. will be.

However, when the ashing treatment is ashed using a gas containing ozone as the ashing gas, since the decomposition in the supply flow path of ozone is prevented, the surface of the wafer set at a high temperature that is cooled to the diffusion plate and is a finned substrate is used. Ozone is thermally decomposed and ashed by high temperature of.

However, when this ashing fixation is performed, it has been found that substantial deposits adhere to the opposite surface of the diffusion plate to the wafer.

If such deposits accumulate, this causes contamination by dust, and there is a problem in that a clean atmosphere suitable for high integration of semiconductor wafers cannot be formed.

Further, when the ashing gas flows out from the plurality of dispersed outlets toward the semiconductor wafer, since the diffusion plate and the semiconductor wafer are in close proximity, the ashing gas does not uniformly contact the entire surface of the surface of the semiconductor wafer, and the irregular ashing occurs. It is to provide an ashing method which can be performed and an ashing device which can implement this method.

That is, the present invention uniformly flows out an ozone-containing gas onto a heated substrate, and generates radicals of oxygen atoms by the heat of the surface of the substrate, and radicals of the oxygen atoms. It is an ashing method provided with the process of ashing the desired film | membrane of the film | membrane coated on the surface of said to-be-processed substrate by radical of an atom.

In addition, the present invention is an ashing device for exhaling the ashing gas to the film coated on the surface of the substrate to be treated, the ashing gas, the chamber containing the stage on which the substrate to be treated, and the ashing gas on the upper side of the mounting stage A nozzle for positioning in the same axial shape opposite the outlet of the nozzle and means for uniformly diffusing the ashing gas discharged from the nozzle onto the target substrate; An ashing apparatus comprising means for supplying the ashing gas of the oxygen gas containing ozone to the nozzle, means for cooling the ashing gas at a predetermined temperature, and exhaust means connected to the chamber.

EXAMPLE

An embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1: is explanatory drawing which shows schematic structure of the ashing apparatus of the semiconductor wafer of one Embodiment to which this invention was applied.

In the figure, reference numeral 10 denotes a processing chamber in which the base 12 on which the semiconductor wafer 11 is placed is accommodated.

The stand 12 is made to adsorb | suck and protect the semiconductor wafer 11, for example by a vacuum chuck. In the stand 12, the heater 14 controlled by the temperature control device 13 is incorporated.

In addition, the mounting table 12 is configured to be movable up and down by the elevating device 15, and to be rotated at a predetermined rotational speed by a rotating device (not shown).

The exhaust device 18 which exhausts the atmospheric gas in the process chamber 10 as a predetermined | prescribed amount of exhaust gas through the exhaust path 16 is connected to the lower part of the process chamber 10.

The exhaust passage 16 is connected to an end point detection device 18 for dividing a portion of the exhaust gas and detecting the end point of the ashing reaction described later.

The cooling device 19 was connected to the upper part of the process chamber 10. The ashing gas supply part 20 is connected in the process chamber 10. The ashing gas supply part 20 supplies the oxygen supply source 20a which determines the composition of ashing gas, the ozone generator 20b, the gas flow regulator 20d which controls the flow volume of ashing gas, and air to the process chamber 10. It consists of the purification mechanism 20c, the dinitrogen monoxide supply source 20e which determines the composition of nitrogen oxide gas, the nitrogen oxide gas generator 20f, and the gas flow regulator 20g which controls the flow volume of nitrogen oxide gas.

In the processing chamber 10, a driving unit 21 for controlling the operation of the ash gas supply unit 20, the temperature control device 13, the lifting device 15, the exhaust device 17, and the cooling device 19, and these The alarm unit 22 is configured to supply a predetermined signal such as an operation stop signal to an apparatus that generates an alarm when an operation of the apparatus of the apparatus occurs and generates a corresponding malfunction.

In addition, the drive unit 21 is configured to control the operation of the wafer supply device 25 that carries in and carries out the semiconductor wafer 11, which is a substrate to be described below, into the processing chamber 10.

2 is a plan view of the wafer supply apparatus.

The wafer supply device 25 automatically loads the semiconductor wafer 11 that performs an ashing to a predetermined position on the mounting table 12 in the processing chamber 10, and performs the ashing so as not to be necessary, for example. This is carried out from the base 12 on which the semiconductor wafer 11 from which the film has been removed is placed. The wafer supply apparatus 25 is comprised as the loader part 25a and the unloader part 25b which carry the unprocessed semiconductor wafer 11 into the process chamber 10. The loader part 25a has the supply part 25a1 which takes out the unprocessed semiconductor wafer 11 from a storage container, and supplies to the next positioning part 25a2. The positioning section 25a2 is provided with a guide 25a3 that abuts against the peripheral surface of the semiconductor wafer 11 and performs positioning thereof.

The guide 25a3 is formed as a fluororesin such as, for example, tetrafluoroethylene. In the supply part 25a1 and the positioning part 25a2, the conveyance belt 25a4 which conveys the semiconductor wafer 11 to a predetermined position is provided. The conveyance belt 25a4 is formed as silicone rubber, for example, and it is provided in the base tables 25a5 and 25a6 formed as aluminum, for example, so that the conveyance circumferential surface may be exposed.

The countermeasure against dust from a belt as conveyance of said conveyance belt 25a4 may be set as the structure which draws the dust which generate | occur | produces by setting a belt conveyance path under pressure.

On both side surfaces of the processing chamber 10, the handle arm 25a7 for transferring the semiconductor wafer 11 from the positioning section 25a2 to the mounting table 12 of the processing chamber, and the semiconductor after the processing at the mounting table 12. The handle arm 25a2 for transferring the wafer 11 to the portion 25b1 on which the unloader portion 25b is temporarily placed is rotatably provided at one end of each arm as an axis. In the portion 25b1 to be temporarily placed therein, a mechanism for cooling the semiconductor wafer 11 in a heated state is incorporated.

In the vicinity of the temporarily placed portion 25b1, a wafer return portion 25b4 for returning the ashed semiconductor wafer 11 to a storage container is provided.

The conveyance belt 25b4 is provided in the wafer return part 25b3 and the temporarily mounted part 25b1 similarly to the supply part 25a1 and the positioning part 25a2.

The protective support of the semiconductor wafer 11 by the handle arms 25a7 and 25a2 is attached to the adsorption portion 25c that is bent to enter the back side of the semiconductor wafer 11, for example, as shown in FIG. By suction and fixedly attached.

The suction part 25c is connected to the suction part which is not shown through the internal path of the handle arms 25a7 and 25a2. 4 is a cross-sectional view showing the internal structure of the processing chamber. The processing chamber 10 is divided into an upper chamber 10a and a lower chamber 10b in order to take out the semiconductor wafer 11 to be ashed.

In the upper chamber 10a, for example, fluorine rubber is formed in an annular shape so that the upper chamber 10a is hermetically collision-bonded with the opening edge portion 10a1 and the opening edge portion 10b1 of the lower chamber 10b.

Separation of the collision joint between the upper chamber 10a and the lower chamber 10b is performed by a cylinder (not shown).

On the cover part 10a2 of the upper chamber 10a, the cooling chamber 10a3 set by the cooling apparatus 19 in the low temperature state of 25 degrees C or less, for example is provided.

This cooling chamber 10a3 is for extending the life of ozone contained in ash gas by cooling the nozzle 26 which blows out ash gas which is demonstrated next.

In this regard, it is known that the lifetime of ozone present in the oxygen gas, depending on the temperature, generally shortens the life of ozone as the temperature increases, as shown in FIG.

Therefore, in this embodiment, ozone in ashing gas is cooled below 25 ° C.

At the centers of the upper chamber 10a and the cooling chamber 10a3, a nozzle 26 is inserted through the nozzles and blows out the ash gas.

The nozzle 26 has, for example, a cylindrical shape having a front end diameter of 8 mm, and has a diameter slightly larger than the diameter of the semiconductor wafer 11 in the plane portion including the outlet 27 of the front end thereof. An insulating plate 28 is installed.

It is preferable that the insulating plate 28 has heat insulation, for example, is formed from a material with low thermal conductivity, such as heat resistant glass and quartz glass which are represented by Pyrex.

The peripheral portion of the insulating plate 28 abuts against the surface of the mounting table 12 so that the distance L between the surface of the semiconductor wafer 11 and the insulating plate 28 is suitably in a range of, for example, 0.5 to 2 mm. The pin 29 for setting slides freely up and down.

Here, it is preferable that the nozzle 26 is connected to the ashing gas supply part 20, For example, it forms with the aluminum pipe of about 2-30 mm in diameter.

In this case, it is preferable that the size of the outlet 27 of the front end is appropriately set in the range of 20 to 40 mm in diameter.

In addition, as shown in a and b of FIG. 6, a diffusion plate 30 formed of, for example, an aluminum plate having a diameter of about 2 to 30 mm is in close contact with a portion in the nozzle 26 near the outlet 27. have.

In the diffusion plate 30, a plurality of small holes, for example, about 0.01 to 5 mm in diameter are drilled.

The diffusion plate 30 diffuses the concentrated wind pressure to the center portion, and flows ashing gas more evenly to the surface of the semiconductor wafer 11 placed on the mounting table 12.

Therefore, a large number of small holes may be formed, and tapered walls may be formed in which the side walls of the surrounding small holes are diffused around. If the ashing gas flows out without providing the diffusion plate 30, the wind pressure in the center portion of the semiconductor wafer 11 becomes high, and it becomes difficult to uniformly ash the entire surface of the surface.

Contact between the lid portion 10a2 and the nozzle 26 is hermetically and through the upper chamber 10a via a seal ring 32 formed of, for example, a fluororesin such as tetrafluoroethylene. When the lower chamber 10b is completely impinged on the joint, the lid portion 10a2 is moved upward and downward with respect to the nozzle 26 so that the insulating plate 28 can set a uniform distance L from the semiconductor wafer 11. It is in a state that can swing a lot.

The upper surface of the mounting table 12 accommodated in the lower chamber 10b is made of, for example, aluminum, and is subjected to anodizing as oxalic acid after surface polishing by honing. The impregnation process of fluororesin is performed thereon, and the generation | occurrence | production of a crack is made into a structure.

In order to smoothly carry out and unload the semiconductor wafer 11 on the inner circumference of the mounting table 12, the handle is lifted up slightly on the mounting table 12 on which the semiconductor wafer 11 is placed during these operations. For example, three lifting pins 31 are incorporated to facilitate the entry and exit of the arms 25a7 and 25ab2.

In addition, the lower part of the mounting base 12 is formed as a single material.

In the contact portion between the elevating pin 31 and the mounting table 12 and the lower chamber 10b, a packing 32 coated with a fluorine resin on a fluorine resin or stainless steel is installed, so that the airtightness of the process chamber 10 is maintained. Keeping up.

Next, the ashing method of the semiconductor wafer by the ashing apparatus comprised in this way is demonstrated.

First, the driving unit 21 is operated to supply the semiconductor wafer 11 that is placed on the mounting table 12 in the processing chamber 10 from the loader section 25a of the wafer supply device 25 shown in FIG. .

A predetermined region on the semiconductor wafer 11 is a film removed by ashing, for example, a Novolac resin or an O-quinone diazide resin (for example, Tokyo, Japan). Orkase, OFPR-800, and OFPR-5000).

In the supply part 25a1, the semiconductor wafer 1 is conveyed to the positioning part 25a2 by the conveyance belt 25a4.

In the positioning unit 25a2, centering of the semiconductor wafer 11, alignment of an orientation plate, and the like are performed.

For example, the centering of the semiconductor wafer 11 is performed by the guide 25a3 abutting the circumferential surface of the semiconductor wafer 11 and fixing it in a correct posture.

Next, as shown in FIG. 2, the handle arm 25a7 sucks and fixes and secures the back side of the semiconductor wafer 11 by the adsorption part 25c, and its one end part is rotated to a pivot point. The semiconductor wafer 11 is moved on the mounting table 12.

At this time, the lifting pins 31 protrude on the mounting table 12, and the semiconductor wafer 11 is supported from the rear surface thereof.

Thereafter, the handle arm 25a7 is returned to its original position, and the lift pin 31 is lowered to determine the position of the semiconductor wafer 11 at the desired position on the mounting table 12.

Next, the position in the processing chamber 10 of the mounting table 12 is set by the lifting position 15, the upper chamber 10a and the lower chamber 10b collide with each other, and the processing chamber 10 is It is set to confidentiality.

At this time, the space | interval 1 of the insulating plate 28 and the semiconductor wafer 11 is a predetermined value in the range of 0.5-2 mm in order to contact the upper surface of the base 12 on which the lower end of the pin 29 puts. Is set.

In addition, the center of the front-end | tip part of the outflow opening 27 is installed so that it may correspond with the center axis | shaft of the mounting base 12 and the semiconductor wafer 11.

The mounting table 12 is already heated by the temperature controller 13 via the heater 14 so as to set the temperature of the semiconductor wafer 11 at, for example, 300 ° C.

Next, the exhaust device 17 performs the preliminary exhaust in the processing chamber 10 while supplying the purge gas from the ashing mechanism 20c.

For example, the gas is evacuated so that the gas pressure is in the range of 700 to 200 Torr.

This preliminary evacuation causes ashing gas to diffuse at high speed, which is useful for speeding up the ashing processing time. If it is not desired to increase the speed, it is not necessary to make a preliminary exhaust.

Here, the upper lid of the upper chamber 10a2 is cooled by cooling the temperature in the cooling chamber 10a3 by 25 degreeC or less by the cooling apparatus 19, prior to discharge of ashing gas.

Oxygen source 20a supplies oxygen to ozone generator 20b, discharges oxygen as ozone generator 20b to generate ozone (O ₃ ), and at 50 to 500 ml / min as gas flow regulator 20d. Adjust to supply ozone to the airtight container.

At this time, for example, nitrogen oxide gas is mixed to promote ashing reaction.

That is, N ₂ O supplied to the N ₂ O gas from the source (20e) to the nitrogen oxide generator (20f), and discharging the N ₂ O gas is used as the nitrogen oxide generator (20f) by NO, NO _2, N ₂ O _4, … Nitrogen oxides of NO _x are generated, adjusted to a flow rate of, for example, 40 to 1000 ml / min as a gas flow controller (20 g), mixed with ozone gas, and supplied into the processing chamber 10 from the nozzle 26 as ashing gas. .

Of course, the reaction promoting gas may not be mixed, but the ashing ratio of the mixture is improved.

Its characteristic is shown in FIG.

Ash gas passes through the diffusion plate 30 and is blown out to the surface of the semiconductor wafer 11 at the outlet 27 of the nozzle 26.

At this time, ozone is brought into contact with the surface of the semiconductor wafer 11 heated at a high temperature, for example, 300 ° C, and thermally decomposed by this temperature, whereby a large amount of radicals of oxygen atoms are generated. The radical of this oxygen atom generates the same reaction as that below with the resist film on the semiconductor wafer 11, so as to ashed the resist film by so-called ashing.

O ₃ → O ₂ + O ^* (1)

C _x H _y + O ^* → CO ₂ ↑ + H ₂ O ↑ (2)

O ₃ + O ^* → 2O ₂ (3)

Here, O ^* is a radical of an oxygen atom, C _x H _y is a resist film.

In this way, the ashing gas is radiated and uniformly applied in the center of the semiconductor wafer 11, and the ashing of the semiconductor wafer 11 is performed.

The gas after ashing is exhausted from the processing chamber 10 by the exhaust device 17.

Part of the exhaust gas is supplied to the end point detection device 18 in the exhaust passage 16.

In the end point detecting device 18, for example, by the wavelength and the absorption of the infrared absorption spectrum as a parameter, to measure the amount of change of CO ₂ in the exhaust gas.

Thus, the end point of the ashing reaction is detected when it reaches a predetermined value of the amount of CO ₂ .

When the end of the ashing reaction is confirmed by the signal of the end point detection device 18, the supply of ashing gas is stopped and the exhaust of the gas in the processing chamber 10 by the exhaust device 17 is stopped. 10a is separated from the lower chamber 10b.

In addition, when the ozone discharged from the exhaust device 17 is decomposed by an ozone decomposer of a thermal decomposition method or the like, for example, pollution can be prevented.

Next, the lifting pins 31 are lifted up, slightly lifted up from the base 12 on which the processed semiconductor wafer 11 is placed, and is adsorbed by the handle arms 25b2.

Next, by the rotation of the handle arm 25b2, the semiconductor wafer 11 after the process is once moved to the base 25b1 for a while.

At this position, the heated semiconductor wafer 11 is cooled.

This cooling can be performed by cooling the stand 25b1 with water for a while.

Subsequently, ashing is completed by transferring from the stage 25b1 where the semiconductor wafer 11 is temporarily placed by the transfer belt 25b4 to the wafer return portion 25b.

In this way, the ashing is carried out. According to the present invention, the following effects can be obtained. That is, the ashing is performed by radicals of oxygen atoms without using an oxygen plasma, so that the ashing can be efficiently performed without damaging the semiconductor wafer 11. In addition, since radicals of oxygen atoms are generated by using ozone, ashing can be performed at a higher speed than when radicals of oxygen atoms are obtained by using ultraviolet rays. In addition, by using an ashing reaction promoting gas such as NO _x in parallel, the ashing ratio can be remarkably improved as compared with the case where the ashing reaction promoting gas such as NO _x is not used in parallel.

In this regard, as the ashing condition, the temperature of the semiconductor wafer 11 is 300 deg. C, oxygen flow rate 10 l / min, ozone concentration 87 g / cm.³, N₂B was applied to a resist film of Novorex-based resin having a film thickness of 1.34 µm, which was set at an O flow rate of 250 ml / min and made of Tokyo Okaze OFPR-800.⁺1 × 10¹⁵In the case where the implantation was carried out under the conditions of 70 KV as ions / cm 2, 32 semiconductor wafers 11 were irradiated, and the average time required until the resist film was completely removed was 90 seconds on average.

On the other hand, in the case shall the addition of NO _x, except that the NO _x other than those present was made under the same conditions, the time taken to remove the resist film was, average 180 seconds.

In addition, by providing the insulating plate 28 above the semiconductor wafer 11, the surface of the resist film, which is the surface to be processed, and the surface of the insulating plate 28 can be set at almost the same temperature, so that an ashing reaction occurs. The ashing ratio can be remarkably improved by adjusting the whole temperature to a predetermined one.

This is confirmed from the test data shown below.

That is, FIG. 7 shows the ashing ratio when the O ₂ gas containing ozone (O ₃ ) flows out as the ashing gas in the center of the semiconductor wafer 11 and the O ₂ flow rate is changed. It can be seen that the ashing ratio increases as the O ₂ flow rate increases.

This property, O ₃ concentration of 4% by weight, 0.5mm gap, a semiconductor wafer between the semiconductor wafer 11 on the side surface of the semiconductor wafer 11, insulating plate 28 made of a glass surface, a heat-resistant side of the insulating plate 28 of the in between 11 ℃ temperature 300, processing time 30 seconds, O ₂ flow rate of 10l / min, l / min, 6l / min, 4l / min, 2l / min., 1l / min characteristics eda example.

9 shows the characteristics of the ashing ratio when the gap is 1 mm.

At this time, the temperature of the semiconductor wafer 11 of the example shows a 300 ℃, O ₃ concentration of 4% by weight,, O ₂ flow rate of 10l / minutes and 5l / min of the distribution between treatment time of 30 seconds.

FIG. 9 shows the influence of the size of the gap of the characteristics shown in FIG. 7 and FIG. 8 on the same coordinate.

Ninth turn O ₃ flow rate of 10l / min, a characteristic between a temperature of the semiconductor wafer (11) 300 ℃, O ₃ concentration of 4% by weight, and the treatment time 30 seconds.

Next, the characteristics of the ashing ratio when the O ₃ concentration is changed are shown in FIGS. 10 and 11.

FIG. 10 shows the distribution of ashing ratio on the surface of the semiconductor wafer 11 when the flow rate of O ₂ is 10 l / min, and FIG. 11 is 5 l / min.

The higher the O ₃ concentration, the higher the ashing ratio, and this tendency is remarkable in the range of 10 mm to 400 mm from the center.

The lower the O ₃ concentration is, the better the nearness of the entire surface of the semiconductor wafer 11 is.

Gaps in the attribute 0.5mm, the temperature of the semiconductor wafer (11) 300 ℃, O ₂ is a flow 10l / min.

Next, the wafer distribution characteristics of the ashing ratio when the temperature of the insulating plate 28 is changed are shown in FIGS. 12 and 13.

FIG. 12 shows O ₂ flow rate 5 l / min when the O ₂ flow rate is 10 l / min.

Moreover, the common condition at this time is O ₃ concentration of 65g / ㎤ (4.5 wt%), the temperature of the semiconductor wafer 300 ℃, the gap is 0.5mm.

It can be seen that the higher the temperature of the insulating plate 28 is, the higher the ashing ratio is, particularly in the region within 50 mm from the center. The deposit on the inner surface of the insulating plate 28 at this time reached the target value at high temperature.

Next, FIG. 14 shows distribution characteristics of the residual film when the ashing time is changed.

This characteristic is, 0.5mm gap, O ₂ flow rate of 10l / min., O ₃ concentration of 4%, 300 ℃ temperature of the semiconductor wafer (11). It can be seen that good ashing properties are obtained at ashing times of 30 seconds or more.

Next, FIG. 15 shows distribution characteristics on the wafer at the ashing ratio when the ashing time is changed.

FIG. 16 shows distribution characteristics on the entire surface of the wafer at the ashing ratio when there is no insulating plate 28. FIG.

Without the insulating plate 28, it can be seen that the ashing ratio is significantly reduced.

However, the same ashing ratio can be obtained.

And the ashing ratio improves in the ashing gas outflow part.

The conditions are, O ₃ concentration is 4 wt.%, O ₂ flow rate of 10l / min, die temperature 300 ℃.

Thus, it turns out that ashing ratio improves by making the surface facing the semiconductor wafer 11 into an insulating plate.

In addition, by providing the insulating plate 28, the temperature of the surface of the semiconductor wafer 11, which is the surface to be processed, and the surface of the insulating plate 28 are made approximately equal, and the temperature of the ashing reaction region is set to a predetermined value. As a result, the temperature drop of the insulating plate 28 can be prevented, and the reaction product can be prevented from adhering to and depositing on the insulating plate 28.

As a result, uniform and efficient ashing can be realized.

Further, a diffusion plate having a plurality of small holes formed in the nozzle 26 by placing the ashing gas as one nozzle 26 and being aligned on the same axis with the center of the semiconductor wafer 11 serving as the substrate to be processed. By spreading the ashing gas on the semiconductor wafer 11 and flowing it out radially through 30, uniform ashing can be realized over the entire surface of the surface of the semiconductor wafer 11.

In addition, in the embodiment, a nozzle 26 that emits one ashing gas is mounted in the upper chamber 10a, and the ashing gas is discharged from the diffusion plate 30 having a plurality of small holes formed in the nozzle 26. 11) was described, but as shown in FIG. 17, the plurality of nozzles 26a. 26e may be inserted through the lid portion 10a2 to blow out ashing gas.

In this case, each nozzle 26a... To gas flow regulator 26d1. It is preferable to install 26d3 and to control the flow rate.

In addition, in FIG. 17, the illustration of the dinitrogen monoxide supply source 20e, the nitrogen oxide gas generator 20f, the gas flow regulator 20g, the end point detection apparatus 18, etc. is abbreviate | omitted in order to simplify description. .

In addition, the plurality of nozzles 26a... The shape of the gas outlet of 26e is formed in the cover part 10a2 by each nozzle 26a... The slits 26a1 may have a plurality of circularly shaped circular slits 26..., As shown in FIG. 18. It may comprise by 26a3.

Alternatively, as shown in FIG. 19, the diffusion plate may include a diffusion plate having openings 26a4 and 26a5 made of a sintered body such as metal or ceramic, as shown in FIG.

In more detail, as shown in FIG. 20, you may comprise with the opening 26a6 (26a7) 26a8 which consists of a diffuser plate provided with the small hole 26f.

Thus, the plurality of nozzles 26a... In the ashing apparatus provided with the 26e, as shown in FIG. 21, the whole surface of the surface of the semiconductor wafer 11 by adjusting the flow volume and ozone concentration of the silver gas containing ozone which flows out for every some area | region. A uniform ashing speed can be obtained at.

In the embodiment of the present invention, the semiconductor wafer 11 is fixed on the mounting table 12, but the ashing is performed while the semiconductor wafer 11 is rotated. The semiconductor wafer 11 may be rotated during the ashing process.

In addition, in the embodiment of the present invention, the process is described as the number of sheets to be ashed one by one, but may be a batch process to simultaneously batch a plurality of semiconductor wafers 11, and the semiconductor wafer is placed on a transfer line. You may ashed while conveying (11), and is not limited to said Example.

Incidentally, in the above embodiment, the example in which the ashing gas is distributed and diffused has been described with reference to FIGS. 17 to 20. However, in the neighboring diffusion holes, one side supplies the ashing gas and the other as the discharge hole. good.

In this case, retention of the exhaust gas can be prevented.

Incidentally, in the above embodiment, the radical gas of the oxygen atom is generated by heating the ash gas, but the radical generation of the oxygen atom may be promoted by the catalyst in the flow path of the ash gas.

Examples of the catalyst include metals such as filadium, platinum, rhodium, manganese, lead, copper, nickel, vanadium and ruthenium, or alumina, silica, and carbon zeolite.

In addition, in the embodiment, the ashing of the resist film on the surface of the semiconductor wafer is described as an ashing target substrate, but not only the semiconductor wafer but also the formation process of the TFT circuit formed on the glass substrate of the liquid crystal display device and the ashing of the printed circuit board. Of course, if the ashing process such as treatment can be applied to any.

Further, the gas containing ozone is not limited to oxygen, which will be used for a gas, in particular N _2, inert gases such as Ar, Ne to not react with the ozone.

Claims (4)

Preparing the gas mixture of nitrogen oxide and ozone excited by discharging the N ₂ O gas, and heating the gas mixture in a reaction region between the surface of the substrate and the surface of 0.5-20 mm above the heated target substrate. Generating radicals of oxygen atoms in the mixture, flowing the gas mixture evenly to cover the surface layer of the substrate, and ashing the desired portion of the substrate surface layer by acting the radicals of the oxygen atoms on the surface layer of the substrate. Ashing method characterized in that it becomes. The ashing method of Claim 1 whose surface temperature of a to-be-processed substrate is the temperature of the range of 150-800 degreeC. The ashing method according to claim 1, further comprising a step of detecting an end point of the ashing reaction by measuring a concentration of a gas produced by the ashing reaction. Preparing a gas mixture of nitrogen oxide and ozone which is excited by performing discharge on the N ₂ O gas; The gas mixture comprising ozone and excited nitrogen oxides is heated to generate a gas comprising radicals of oxygen atoms, and the gas comprising radicals of oxygen atoms radially from the center of the substrate to the circumference thereof. By uniformly flowing over the surface of the substrate, the gas mixture is brought into contact with the surface of the substrate and the desired portion of the substrate surface layer is ashed by the reaction of the radicals of the oxygen atoms with the surface layer of the substrate. .

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