JPS62165935A - Detector for end point of ashing - Google Patents

Abstract

PURPOSE:To obtain an ashing end-point detector adequate to sheet processing by mounting an exhauster and a measuring instrument for the specific quantity of a gas to an ashing device using a gas flow containing O3. CONSTITUTION:A gas outflow section 22 is oppositely arranged separated at a set interval from a wafer 28, and O3+O2 gases from an opening for a plate section in the section 22 are cooled at 15-50 deg.C by a cooler for the outflow section 22, and fed to the wafer 28 temperature-regulated 6 at 150-500 deg.C. A gas formed by a chemical reaction with a film on the surface of the wafer 28 is discharged 4, the quantity of CO2 gas is measured by a gas analyzer 7, and the time when gas concentration is reduced to a predetermined value or less is detected 8, and decided to be the completion of ashing. The wafer or the gas outflow section can be moved vertically. According to the device, the film applied onto the wafer can be ashed and treated without damaging the wafer.

Description

[Detailed Description of the Invention] [Field of Application in Industry-1-] The present invention relates to an ashing end point detection device (ashing end point detection device) for removing a film deposited on a wafer, etc.
The present invention relates to an ashing end point detection device suitable for single-wafer processing in which a photo resist film (hereinafter referred to as resist l-) of UNINO X1- is oxidized and removed using ozone.

[Prior Art] Formation of fine patterns in semiconductor integrated circuits is generally performed by etching a t-layer formed on a wafer using an organic polymer resist film formed by exposure and development as a mask.

Therefore, the resist film used as a mask needs to be removed from the surface of the wafer after the etching process. Ashing processing is performed to remove the resist in such a case.

This ashing process is called registry limping.

It is used for cleaning silicon wafers and masks, removing ink, removing solvent residue, etc., and is suitable for dry cleaning in semiconductor processes.

As the ashing process for removing the rust, oxygen plasma is generally used.

Resist ashing using oxygen plasma involves placing a wafer with a resist film in a processing chamber, converting the oxygen gas introduced into the processing chamber into plasma using a high-frequency electric field (1), and ashing the resist, which is an atomized material, by the generated oxygen atomic radicals. It utilizes the action of oxidizing and decomposing it into carbon dioxide, carbon oxide, and water, which are then vaporized.

However, the ashing process using oxygen plasma has the drawback that the wafer is irradiated with ions and electrons accelerated by the electric field present in the plasma, which adversely affects the electrical characteristics of the semiconductor integrated circuit.

To avoid such drawbacks, UV light (
There is a device that generates oxygen atom radicals by irradiating UV light and performs ashing processing in batch processing. This type of apparatus has the advantage of being able to perform efficient stripping and cleaning without damaging the elements, since there is almost no damage to the elements due to the electric field compared to plasma processing.

FIG. 17 shows a conventional ashing device using ultraviolet irradiation.

In the processing chamber 100, a large number of wafers tot, t.

1...Fists are arranged vertically at predetermined intervals, and the processing chamber 1
Ultraviolet light from the ultraviolet light emitting tube 103 installed at -IJ< of 00 passes through a transparent window 102 made of quartz or the like provided on the top surface of the processing chamber 100! 16 rays to excite the oxygen filled in the processing chamber 100 and generate ozone. Oxygen atom radicals generated from this ozone atmosphere are then transferred to the wafer 1.
01 to perform ashing processing.

By the way, in recent years, there has been a trend toward larger wafers [1 diameter].
Along with this, single-wafer processing methods in which wafers are processed one by one are becoming common.

[Problems to be Solved] The above-mentioned ashing process using ultraviolet irradiation has the advantage of not damaging the wafer, but has the disadvantage that it takes time because it is a batch process. Moreover, since the action is performed in an ozone atmosphere called li, the resist ashing speed is 500 to 1500 people/mIr,
It's just a matter of degree.

On the other hand, single-wafer processing for large-diameter wafers usually requires a processing speed of about 1 μm to 2 μm/min, and conventional equipment that irradiates ultraviolet rays cannot adequately handle single-wafer processing. .

Furthermore, since ultraviolet rays are used, the device has to be large and expensive.

[Purpose of the Invention] Therefore, in order to eliminate the problems of the prior art, the present inventors have developed a method of "providing a flow space in contact with the wafer through which a gas that removes ozone flows, and The company proposes a technology that oxidizes and removes the deposited film.

Here, in order to ensure that the ashing process is completed completely, it is necessary to secure an extra ashing process time with some margin. In addition to processing overhead, this may lead to a situation in which a wafer that has been completely ashed must be further ashed, which may even increase the risk of damage to the wafer.

For this reason, in order to perform a more complete and reliable ashing process and improve the operating rate of the equipment by 1x, it is necessary to detect the end point of the ashing process and move on to the next ashing process in a short time. This occurred and I was able to resolve this issue.

SUMMARY OF THE INVENTION Therefore, in view of the problems of the prior art described in item n'1, an object of the present invention is to provide an ashing end point detection method that can solve these problems.

[Means for Solving the Problems] The means of the ashing end point detecting device of the present invention to achieve such an object is to provide a flow space in contact with the wafer through which a gas for doweling ozone flows, and to detect the wafer surface. This is an ashing end point detection device used in an ashing processing system that oxidizes and removes a film deposited on a surface by a chemical reaction, and detects a change in the concentration of a specific gas generated as a result of the chemical reaction to detect the end point of the ashing process. The purpose is to determine the

[Operation: For example, an ozone outlet is provided at a position facing the wafer at a predetermined distance to form a gas flow space of ozone + oxygen between the wafer and the wafer to continue supplying new ozone to the Unino λ surface. . This promotes the oxidation chemical reaction between the oxygen atom radicals and the film adhered to UNINO 1, and also vaporizes carbon dioxide, -carbon oxide, water, etc. generated after the reaction by non-radical oxygen (02). It can be moved and ejected from the wafer surface.

As a result, the reaction surface of the film 1, such as an organic film, deposited on UNINO 1 can be efficiently exposed to the oxygen radicals, which have a very strong oxidizing action.

Therefore, high-speed ashing processing can be performed, and ashing processing suitable for single-wafer processing can be realized.

Then, when moving from the ashing process to the next a, nosing process, the concentration of a specific gas produced as a result of the chemical reaction in the above-mentioned process is monitored, and the ashing process is performed based on the change in concentration. Detect the end point. As a result, the transfer time can be shortened, and the ashing process can be carried out reliably for each sea urchin 1, thereby realizing high-speed single wafer processing with little risk of damaging the wafer.

[Example 1] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an ashing processing system according to an embodiment to which the ashing end point detection device of the present invention is applied, and FIG. FIGS. 3(a) and 3(b), which are cross-sectional explanatory diagrams showing the configuration, are specific explanatory diagrams of the electrostatic chuck in the wafer transfer mechanism, where (a) is the I-
FIG. 4 is an enlarged explanatory view of the reaction part; FIG. Figures 5 (b) and (C) are diagrams explaining the relationship between the diffusion aperture and the ashing state on the wafer, respectively, and Figure 6 shows the relationship between the decomposition period of ozone and the amount of diffusion at 1 part of 27111 degrees. It is a graph explaining the relationship between.

In addition, Fig. 7 is a graph explaining the relationship between the wafer surface lL1 degree and the fusing speed at 300°C and the gas flow rate [4], and Fig. 8 is a graph explaining the relationship between the surface temperature of Unino 1 and the gas flow [4] at 300°C.
Figure 9 is a graph illustrating the relationship between the ashing speed of the diffuser plate and the gear knob of the surface of Urchin/1 in C.
Figures 10 (a), (b), (c), and (d) are explanatory diagrams showing the relationship between gas temperature and resist removal〉♀(, respectively. Figure 11 (a), (
b), (C), and (d) are explanatory diagrams of specific examples of the gas cooling structure in the injection part, respectively, FIG. 12(a) is an explanatory diagram of the method of rotating the gas injection part, and FIG. b) is
FIG. 13 is an explanatory diagram of rotating the wafer side. FIG. 13 is an explanatory diagram of the non-ring effect when the wafer side is not rotated. FIG. FIG. 15 is a graph showing changes in the concentration of carbon dioxide in the υ1 gas, and FIG. 16 is a graph explaining the relationship between the ashing rate and the ozone concentration.

In FIG. 1, ■ indicates A11. The ashing processing system includes an ashing device 2 and an ashing device 2.
an ozone + oxygen gas supply device 3 that supplies oxygen gas containing ozone to the ashing device 2, an exhaust device 4 connected to the ashing device 2, and a wafer mounting table 2 disposed inside the ashing device 2.
h' for moving the wafer up by 1-1, a lowering device 5, and a temperature controller 6 for adjusting the heat generation state of the heating device 2La installed in the wafer mounting table 21 to control the temperature of the wafer at 761 degrees. .

The ozone + oxygen gas supply device 3 includes a gas flow regulator 3
a, an ozone generator 3b, and an oxygen supply source 3C, and the ozone concentration, gas flow rate, a.

The gas pressure in the processing device 2 (processing chamber) is determined by the gas flow rate regulator 3a + ozone generator 3b, oxygen supply source 3.
It is adjusted depending on the relationship between c and the exhaust device 4.

In particular, the ozone concentration supplied to the ashing device 2 is adjusted by the ozone generator 3b and set to a predetermined value.

Further, the wafer mounting table 21 disposed inside the ashing device 2 holds the wafer 28 by suction, and the temperature of the held wafer 28 is tII! It is maintained at a predetermined value by the degree adjuster 6.

One part of the wafer 28 has a distance of 0.5 to 20 m from its surface.
Circle m where ozone + oxygen gas is injected at intervals of about m
A cone-shaped injection section 22 is provided, and the above-mentioned interval is set to a predetermined value as the wafer mounting table 21 is raised by the lifting device 5. In this case, the injection part 22 side may be moved downward by a lifting device.

The injection part 22 is made of SUS (stainless steel), AJI, or the like, and has a disc-shaped diffusion plate part 22a parallel to the surface of the wafer 28 facing the wafer 28. In the process of loading and unloading the wafer 28, the wafer mounting table 21 is lowered by the lifting device 5, the space between the diffusion plate section 22 and the wafer 28 is expanded, and the arm of the wafer transport mechanism is inserted into the space. This is done by intruding.

Now, the ashing process is performed by heating the wafer 28 on the wafer mounting table 21-1 to a temperature in the range of about 150°C to 500°C, especially to a specific value of 200°C to 350°C, and the ozone generated What is the mixing ratio of ozone and oxygen due to ozone generation? Adjust with 9I3c. And oxygen gas containing this ozone.

For example, about 3 J to 15 J/min is sent into the chamber of the ashing device 2, which is a processing chamber. The gas pressure inside the ashing device 2 at this time is, for example, 700 to 200 Torr.
Set it to a range of about r.

Next, handling of the wafer 28 into and out of the processing chamber of the ashing apparatus 2 will be specifically explained based on the ashing apparatus 30 shown in FIG. Note that this ashing device 30 is different from the ashing device 2 shown in FIG. 1 in that the spraying section is moved L-up instead of moving the wafer mounting table up.

In FIG. 2, the ashing device 30 includes a processing chamber 20 and loader/unlower 7 sections 23a and 2 disposed on both sides thereof.
3b and these loader/unloader ffi<23a, 2
Belt conveyance mechanisms 24a each installed inside 3b,
24b.

Here, the loader/unloader FM<23211 belt transport mechanism 24a is the side that carries in the wafer, and the loader/unloader section 23b and belt transport mechanism 24b are the side that carries out the ashed wafer. It may be the side or the unloading side. Furthermore, there may be only one loader/unloader section.

Although not shown, the belt conveyance mechanisms 24a, 2
A cartridge for storing wafers stacked at predetermined intervals is installed at the opposite end of 4b, and as this cartridge moves up and down, unprocessed wafers are sequentially transferred from the cartridge to the belt transport mechanism 24a. It is fed into the loader/unloader section 23a. The ashed wafers are sequentially stacked and stored in the cartridge from the loader/unloader ffi<23b via the belt conveyance mechanism 24b.

Now, the processing chamber 20 is made of, for example, SUS, Aλ, or TIN.
A wafer mounting table 205 is installed at the center of the chamber 29 coated with Aλ. A gas injection part 22a is supported on the ceiling side of the chamber 29 so as to be movable downward by -1 unit at a predetermined interval.

Gas injection here! I< 22 a has a conical shape consisting of a disc-shaped diffuser plate 200 and a cone part 203 connected to its -t, and the cone part 203 contains ozone +
An oxygen gas introduction pipe 202 is connected at the -L section, and the introduction pipe 202 is hermetically surrounded by a metal bellows 201 made of SUS or the like so that it can be moved down one unit. The syn+oxygen gas necessary for the reaction is introduced.

204 is a cooler for ozone + oxygen gas that spirally surrounds the outer circumference of the cone portion 203;
03 with heat conductive cement or the like. The cooler 204 has a structure in which the refrigerant is introduced from the lower side of the cone portion 203, discharged at the apex portion thereof, and guided to the outside.

On the other hand, as shown in FIG. 4, the diffusion plate 200 has a slit (opening D) 31 for blowing out the gas, and blows the cooled ozone + oxygen gas uniformly onto the surface of the wafer 28. put out.

The diffuser plate 200 is supported at three points around its periphery by pole screw mechanisms 231, 232, and 233 at approximately 120° intervals, and is moved up and down.

It is driven by pole screw mechanisms 231, 232.
The gears formed on the ball parts 234, 235, and 238 (not shown in the figure) of the motor 233 are connected to the motor 23.
This is done by meshing with a worm gear carved into the rotating shaft 236 of the 0.

In addition, the elevating mechanism of the injection part 22a may not be a combination of such a motor, a ball screw, and a gear, but may be configured to directly move the injection part 22a downward using an air cylinder or the like.

In the position shown in the figure, the injection unit 22a is in the 1-up state (standby position), and the wafer 28 is placed on the wafer mounting table 20.
It is in the relationship of being carried into or carried out from 5. On the other hand, as shown in FIG. 4, when the injection ffi<22a falls, the blowout of the diffuser plate 200 is spaced from the wafer surface by 0.5 to several mm, or several IO m+ (reaction position). Thus, it is positioned on a part of the wafer mounting table 205, and gas is supplied to the surface of the wafer 28 on the wafer mounting table 205.

Note that a heating device 206 is installed inside the wafer mounting table 205 to heat the wafer mounting table 205. In this example, in addition to the gas containing ozone, the chamber 29 also contains N2 to cover the gas flow from the diffusion plate 200.
gas is introduced.

Now, 26a is a suction chuck part supported on the tip side of the transfer arm 25a, and loa is a suction chuck part 26 that moves up and down with respect to the main body of the suction chuck part 26a.
This is an electrostatic chuck supported by a. In the figure, wafer 2
8 is shown being attracted to the electrostatic chuck 10a. In this case, the wafer may be attracted by negative or positive suction 7t, or may be mechanically clamped or held.

The other end of the transfer arm 2521 is fixed to a support 27a disposed within the loader/unlower 7 section 23a, and the transfer arm 2521 is
Unloader section 23a and wafer mounting table 205 in processing chamber 20
This is a frog leg transport mechanism type arm that moves back and forth between the Note that this transfer arm 25a may be constructed of a magnetic cylinder, an air cylinder, or the like.

Here, the reason why the frog leg transport mechanism is used is that the transport mechanism section can be made smaller, and, for example, ashing processing chambers are provided on both sides of the loader/unloader section, so that the support 27a of the frog leg transport mechanism can be rotated. If you do that,
Since the frog leg transport mechanism can be directed to the desired chamber side, there is an advantage that wafers can be selectively transported or unloaded to both chambers.

In addition, a loader/unloader section is provided linearly between the belt conveyance mechanism and the chamber, and its support 1, L27 a
If the wafer is made to rotate i+J, it is also possible to similarly pick up the wafer from the belt transport mechanism, turn it over, and transport it to the chamber. It can be realized as something.

Now, the loader/unloader section 23b is also provided with a similar frog leg transfer mechanism-type transfer arm 25b, a suction chuck section 26b, its electrostatic chuck 10b, and a support 27b in a symmetrical relationship. In the figure, a processed wafer 28 is attracted to the electrostatic chuck 10b.

Therefore, the wafer mounting table 205 is provided with a plurality of holes 220 for negative pressure suction. In addition, the wafer mounting table 2
Around the ring plate 2, there are a plurality of air openings 219, 2190 and 2190, which are provided at predetermined intervals in an annular manner, in order to discharge the exhaust gas after the reaction as evenly as possible.
22, this ring plate 222 is
It is fitted into the outer circumferential side of the wafer mounting table 205 at a position slightly below the -1- plane of the wafer mounting table 205.

Reference numerals 221 and 223 are exhaust pipes for aerating the chamber 29, and are connected to the pump of the exhaust device 4. Two or a plurality of these exhaust pipes 22L and 223 are provided so that exhaust is evenly performed, but the number of exhaust pipes 22L and 223 may be one. Further, 224 and 225 are gate valves, respectively.

Further, 228 and 227 are belt conveyance mechanisms 24, respectively.
A and 24b are conveyor belts, and 217 and 218 are chambers of the loader/unloader sections 23a and 23b.

Here, the chambers 217 and 218 of the loader/unloader sections 23a and 23b may also be evacuated to υF by a vacuum pump in accordance with the internal pressure of the chamber 29.

Next, to explain the operation of this device, the injection part 22
Assume that a is set to the -* barking state, held in the standby position, and the valve of the gas inlet 202 is closed.

When the gate valves 224 and 225 are closed, the inside of the chamber 201 is in a reduced pressure state close to normal pressure.

In addition, in the case where the wafer installation table 21 shown in FIG. 1 is raised and lowered, the lifting device 5 is driven to lower the wafer installation table 21 and set it at the standby position. However, the relationship between the loader/unloader section is the same as that shown in FIG.

Now, in this state, the gate valve 224 is opened, and the wafer 28 carried into the loader/unloader section 23a from the belt transport mechanism 24a is lowered by its electrostatic chuck]Oa, and a voltage is applied to it to transfer it to the suction chuck. It is adsorbed by 26a. Then, the electrostatic chuck 10a is raised once and the wafer 28 is pick-amplified. Next, transfer arm 2
5a and transports the adsorbed wafer 28 from the loader/unloader section 23a to the processing chamber 20, and transfers it to the wafer mounting table 2.
05.1- and lower the electrostatic chuck 10a, and lower the applied voltage to zero to allow the wafer 28 to fall under its own weight. Then, the wafer is placed on the wafer mounting table 2051 by applying negative pressure to the wafer mounting table 205 side.

Next, after the electrostatic chuck 10a is moved -I, the transfer arm 25a is contracted and the suction chuck 26a is returned to the loader/unloader ffi<23a. Suction chuck 26a
After the loader/unloader ≦ has moved, the gate valve 224 is closed, the injection section 22a is lowered to the reaction position, and the diffusion plate 200 is set at the reaction position shown in FIG.

In the case of the ashing device 2 shown in FIG. 1, the wafer 28 is placed at the reaction position when the wafer mounting table 21 is raised by the lifting device 5.

Here, the temperature of the wafer 28 is monitored, and when it reaches a predetermined anothing processing temperature, the gas is introduced immediately.
The valve No. 2 is opened, and ozone and oxygen gas are evenly sprayed onto the surface of the wafer 28 placed on the wafer mounting table 205.

As a result, the resist on the wafer 28 is oxidized, and the gases generated by this chemical reaction, such as dicarbonate, carbon oxide, and water, are sent to the exhaust pipes 221 and 222 by the exhaust device 4 together with the oxygen after the reaction. After passing through, υ1 becomes ki.

When the ashing process is completed (for example, 1 min to several min), close the gas introduction valve 202,
Move the diffuser plate 200 to the standby position by -1-ν11 (first
In the figure, the wafer mounting 205 is lowered to the standby position), the gate valve 225 is opened, and the transfer arm 25b is moved from the loader/unloader section 23b to the processing chamber 20.
is extended, the suction chuck 26b is moved onto the wafer mounting table 205, and the electrostatic chuck Job on the tip side thereof is lowered to apply a voltage thereto. Then, the ashing-treated sea urchin/128 is adsorbed on the wafer mounting table 2051, and the electrostatic chuck 10b is moved to pick it up. After raising the electrostatic chuck loa by -1-, the transfer arm 25b is contracted and the processed wafer 28 is transferred to the loader/unloader section 23b.

The wafer thus carried out to the loader/unloader section 23b is transferred from the loader/unloader section 23b to the belt conveyance mechanism 24b, and is housed in a cartridge, where the ashed wafer is taken out of the apparatus.

Here, the electrode portion of the electrostatic chuck will be explained. In addition, in FIG. 1, the electrostatic chuck 10a.

Since the lOb has the same configuration, in the following description, the electrostatic chuck 10 will be explained, and its electrode portion will be referred to as the electrostatic chunk electrode portion 17.

Now, as shown in FIGS. 3(a) and 3(b), the electrode part 17 of the electrostatic chuck 10 for wafer suction has a semicircular plate shape with semicircular recesses 11a and 12a provided inside the back surface, respectively. It is formed by first and second electrodes 11 and 12 made of a conductor such as metal.

By the way, when automatically transporting a wafer, it is overwhelmingly necessary to pick up and transport the wafer from the front side. Therefore, the electrode section 17 is attached as an electrostatic chuck in a state where it is suspended from the wafer transfer device so that the suction surface thereof is located at the bottom.

Here, these first. The second electrode 11.12 is the insulating film 1
3.14, and are arranged at predetermined intervals. This gap may be left as a void, or an insulator may be inserted depending on the structure. The selection may be determined based on the overall structure of the electrostatic chuck 10.

1st. As shown in FIG. 3(a), the second electrodes 11 and 12 have a substantially semicircular outer periphery with a radius R, leaving a portion of width W, and the inside is concave (depth h). The part W serves as a suction part 15, 16 for the conductor wafer. Adsorption part 1
The insulating film 13.1 is formed on the surface of each of 5.16.
4, an insulating film 15 al 18 a is provided as a coated layer, and these insulating films 15
The film thicknesses of a and lea are determined based on the suction force of the wafer and the like. The thickness of the insulating films 13 and 14 other than this portion is determined in consideration of the fact that this 7u pole portion has sufficient breakdown voltage when it comes into contact with other metal portions.

Next, the ashing process will be explained in detail with reference to FIGS. 4, 5(a), and 6.

As shown in FIG. 4, in the ansing process, the ozone supplied from the ozone + oxygen gas supply device 3 is in the following thermal parallel state inside the injection part 22a (or the same applies below to the injection part 22). It becomes.

03ko02 +0 In this case, the life of the oxygen atom radical O obtained by decomposing ozone depends on the degree of Nr'A+, and as shown in Figure 6, it becomes very long at around 25°C. There is.

However, when the lu degree becomes J:W-, the life span becomes rapidly shortened.

- On the other hand, the ashing process using oxygen atom radicals is an oxidation chemical reaction, and the higher the temperature, the faster it occurs.

Furthermore, it takes a certain amount of time for the oxygen atom radicals to act on the wafer surface. So wafer 28
An important issue is how to continue to efficiently supply oxygen atom radicals to the surface of the substrate.

The ansing process proposed in this invention efficiently supplies oxygen atom radicals to the surface of the wafer 28 and rapidly removes reaction products from the wafer surface. In the synergistic treatment with the supply of radicals, the ashing speed can be increased to a processing speed suitable for single wafer processing.

Therefore, it is important to create an appropriate gas flow space that supplies oxygen atom radicals and removes reaction products.

In this embodiment, as shown in FIG.
00.

The distance between the wafer mounting table 205 and the diffusion plate 200 is relatively narrow, and if the heating temperature of the wafer 28 is set high, it can be set to about 0.5 to several mm from the wafer surface. It becomes necessary. In addition, the injected gas is blown out 5 mm or more outward from the outer shape of the wafer 28.
The outermost opening position (the position of the slit 31a in FIG. 4) has been determined.

By blowing the gas outward from the outer circumference of the wafer 28 in this way, a negative pressure region is formed by the gas flow on the outer side of the wafer outer circumference, and the generated gas from the center side is more quickly transported to the outer side of the wafer outer circumference. It is something that is discharged.

As a result, the supply of ozone and the contact of arsenic and oxygen atom radicals to the wafer surface are facilitated, and the oxidation reaction can be promoted.

Now, the ozone + oxygen cooled by the cooler 204 is
For example, it is cooled to about 25 to 50°C.

Therefore, the oxygen atom radicals are transferred to the cone part 20 of the injection part 22a.
3. The rate held internally increases.

As soon as ozone COa, 02 +0) and oxygen 02 are injected from the opening [-1 part of the diffusion plate 200, they are exposed to a high temperature atmosphere, but before their lifespan ends, they reach the wafer surface together with oxygen. Ashing (ashing) the film deposited on the wafer surface.

that is, oxidized and removed from the wafer surface).

As shown in FIG. 5(a), carbon dioxide, -carbon oxide, and vaporized water generated by ashing are simultaneously exposed to oxygen (02) and non-radical ozone (03) which are ejected from the diffuser plate 200. ) is removed from the surface, carried from the exhaust opening 219 of the ring plate 222 to the exhaust pipes 221, 223, and sequentially evacuated by the exhaust system 4.

Therefore, an environment can be created in which the surface of the wafer 28 is constantly exposed to oxygen atomic radicals.

In FIG. 5(a), 28a is a surface portion of the wafer 28, 28b is a resist portion adhered to the wafer 28, and an arrow 32 indicates ozone + oxygen from the diffusion plate 200. It shows the flow of gas.

Here, the wafer temperature is set at 300°C, and the standard state at the opening of the diffuser plate 200 ( Gas flow 2 under normal temperature and pressure conditions
When we measured the ashing speed for
Particularly high-speed ashing processing is possible in the range of 0 sJ (sJ!: normal l! l! + flow fn in terms of normal pressure), and it gradually becomes saturated from about 40 sJI/min.

In order to make this flow rate correspond to the general wafer diameter, it is converted to flow rate u per C114 area of the wafer, which is 0°0
1 to 0.25 sJ/min @cffil.

Furthermore, when the relationship between the ashing speed and the gear between the diffuser plate and the wafer surface is measured using the gas gap as a parameter at a wafer surface temperature of 300°C, as shown in Figure 8, when the gap is 20 mm or more, , regardless of the gas jet flow h1, exhibits a characteristic that converges toward a constant value.

Furthermore, regarding the relationship between the temperature of the gas ejected from the diffusion plate 200 and the resist removal rate, the gap to the wafer (the distance from the surface of the wafer 28 placed on the wafer mounting table 205 to the surface of the diffusion plate 200) 2 mm and reaction time of 1 min, we measured its characteristics using the gas flow rate as a parameter.As shown in Figure 9, we found that it was difficult to remove when the temperature was raised to about 200°C. It can be understood.

Therefore, when the reaction is carried out by heating the wafer side to 200° C. or more, it is preferable to cool the injected gas (ozone + oxygen). As a particularly preferable range, the temperature of the outflow gas of the diffuser plate 200 is 15 to 50.
It is at °C.

This agrees with the characteristics of the half-life of ozone decomposition, which we saw in Figure 6.

Furthermore, as shown in Figure 16, when we investigate the relationship between the ashing rate and the ozone concentration, we find that the ozone lQ degree is -
As L increases, the ashing speed increases -IJi'-. However, if it exceeds about 10% by market weight, it will shift toward saturation. Note that this characteristic is for a 6" wafer, whose 4 degrees is 250'C, and the gas flow rate is 5".
sλ/min, and the chamber pressure was about 7QQ Torr, and was measured on a resist hardened by plasma irradiation in an etching process.

As can be understood from each characteristic graph, by forming a flowing gas space in the second part of the wafer and injecting or flowing ozone-containing gas onto the wafer,
Ashing processing of several μm/rBin becomes possible. This realizes ashing suitable for single wafer processing and processing of large diameter wafers.

FIGS. 10(a) to 10(d) are explanatory diagrams of specific examples of a diffusion plate 200 that uniformly injects ozone+oxygen gas onto the surface of a wafer.

FIG. 10(a) shows four arcuate slits 311 formed circularly and concentrically, and these grooves may be perpendicular to the wafer, but gas flows outward. The grooves are diagonal so that the gas flows outward to form a hole.

In FIG. 10(b), a hole 312 is provided in the center of a circle, and slits 313 are arranged radially with respect to the hole 312. In FIG. 10(C), holes 314 are provided radially, and the name tag 314 becomes slightly larger toward the outside. 1st
FIG. 0(d) shows a case where a sintered alloy 200a is used as a diffusion plate 200, and porous holes 315 are formed over the entire surface of the plate.
uniformly.

In FIG. 10(e), the injection port 316 is formed in a spiral shape, and in FIG. 10(f), the small hole 316 is simply formed in a circular shape.
17 is worn.

Here, in order to examine the effect of uniformly discharging gas from the diffusion plate 200, we will examine two cases: a case in which holes are sparsely opened as shown in FIG. 10(f), and a case in which holes are opened sparsely as shown in FIG. In the former case, as shown in Figure 5(b), when comparing the case where the porous pores are uniformly distributed, as shown in Fig. 5(b),
The resist portion 28b is ashed in response to the gas flow 32 (arrow), and the ashing becomes uneven with gentle waves. On the other hand, in the case of the latter sintered alloy in which porous pores are uniformly distributed, uniform ashing is performed as shown in FIG. 5(C).

Therefore, the gas injection [I
This has the advantage that the processing time until complete ashing can be shortened and that the wafer is not easily damaged even if ozone is applied to the wafer surface. In addition, in FIGS. 5(b) and 5(C), the portion indicated by the dotted line is the surface position (thickness) of the resist before unsinging.

Now, as seen in the characteristic graphs in Figure 6, etc., gas (
It is better to inject ozone + oxygen from the diffuser plate in a state as cool as possible.

By the way, the distance between the wafer mounting table 205 and the diffusion plate 200 is relatively short. On the other hand, the wafer mounting table 205 and the wafer 28 are heated by the heating device 206 to a reaction lK1 degree. Therefore, the diffusion plate 200 is
The surface of the diffuser plate 200 tends to rise in temperature as it is heated by radiant heat etc. radiated from the side of the diffusion plate 200 and the surface of the diffuser plate 200.

As a result, the temperature of the gas increases near the injection point [1], and the amount of oxygen atom radicals supplied to the wafer surface decreases. Especially gear 1. If the curve is large, the effect of heat will be somewhat reduced, but since the time taken for the oxygen atom radicals to travel will be longer, the life of the oxygen atoms will be exhausted by the time they reach the surface of the wafer 28, including the influence of temperature and Lv1'. There will also be more radicals. It's a master, if the gear knob is too small, Unino\, 1 (
Directly affected by 1 degree tl on the I2 mount 205 side, the lAλ degree 1-rise on the surface of the diffuser plate 200 tends to be 6 times higher. Moreover, the gas flow blown out from the diffusion plate 200 fits
Depending on the temperature, the two loaf values will also differ.

For this reason, there are more optimal conditions for an/ing processing. In the reaction mode shown in Fig. 4, when the temperature of the sea urchin/% is 200'C to 350°C, the optimal gear and knob are about 1 to 3 mm, and the gas diversion is For 6# wafer under the conditions of room temperature and pressure, 5. 5~17s J! /min. Therefore, when converting this to the flow rate per unit surface area of UNINO 1, it is 0゜03~0゜1sJt/mln*c
It becomes ITI'.

In addition, carbon dioxide reacted by oxygen atom radicals, -
Considering that reaction products such as carbon oxide and water are carried away from the wafer surface mainly by oxygen (02),
There are more efficient ozone and oxygen weighting percentages.

That is, if the amount of ozone (03) is low, the ashing rate (the rate of decrease in the 91st time relative to the film thickness) will be low, the uniformity will be poor, and the efficiency will be poor. On the other hand, if the amount of ozone (03) is large and the amount of oxygen (02) is small, the rate will be high, but the reaction product will stagnate on the wafer surface and the reaction rate will decrease.

Taking these points into consideration, the optimal ozone I″r
As CI'i 1%, approximately 3% by weight to 5% by weight H1% is suitable.

Now, taking such things into account, a specific example of a cooling structure for the injection part that injects gas at a temperature as low as possible in addition to uniformly injecting gas will be described next.

The injection part 22b shown in FIG. 11(a) has a cooling pipe 204a made of a coiled pipe also arranged on the inner surface of the diffusion plate 200, and communicates with the cooler 204. This is made to extend in a meandering manner while avoiding the slit 318 for this purpose.

In addition, the injection part 22b shown in FIG.
A cooling pipe 2 made of a coiled pipe is installed on the outer surface of the 00 (wafer 28 side).
04b is arranged and communicated with the cooler 204, and similarly, it is made to snake in a meandering manner while avoiding the slit 318. In this case, the cooler 204 disposed around the cone portion 203 may not be provided in FIGS. 11(a) and 11(b).

By doing so, even if there is heat radiation from the wafer mounting table 205 side, the surface of the diffuser plate 200 can be suppressed to a low state, and the temperature of the gas to be injected can be suppressed, allowing more flexible conditions. I'd be able to perform an efficient ashing process.

The injection part 22c shown in FIGS. 11(c) and 11(d) has a cylindrical shape rather than a conical shape, and has a dome 22d for gas diffusion at the 11th part, and this dome part After the gas is diffused in advance, it is sent to the diffusion plate 311 having slits or the diffusion plate of the sintered alloy 200a.

In particular, in FIG. 11(C), a serpentine tube-shaped cooler 204c is built inside the cylindrical portion, and in FIG. 11(d), a ball 200b with a relatively large diameter is installed in order to make the injection uniform. There is plenty of space inside. Note that although these are not provided with a cooler on the outside, similar to FIGS. 11(a) and (b),
Of course, a cooling pipe may be placed outside the cylindrical portion.

Next, an example will be described in which the wafer and the diffusion plate are rotated relative to each other in order to blow gas more uniformly onto the wafer surface and further promote the oxidation reaction.

The injection part 33 shown in FIG. 12(a) consists of a diffusion tube 34 and a gas introduction tube 35 communicating at the center thereof, and the gas introduction tube 36 is rotatably connected to the ceiling side of the chamber 29. It is pivotally supported.

Here, both ends of the diffusion tube 34 are closed, and a jet +138.36. ... are arranged at predetermined intervals. Furthermore, LI is injected at positions on opposite sides of the edges (sides perpendicular to the wafer surface) with their backs turned to each other.
I37.38 is provided, and by injecting gas from there, the diffusion tube 34 rotates by itself due to the reaction. Moreover, the gas injected from both ends of the wafer 28
It also plays the role of transporting the ashing product to the outside. In addition, injection [instead of 136,
The diffusion tube 34 may also be made of a porous material.

In the example shown in FIG. 12(b), the wafer mounting table 205 is axially supported, this support is pivotally supported on the floor side of the chamber 29, and the wafer mounting table 205 is rotated by a motor. It is. In addition, the injection part 22a is shown in FIG.
) may be tubular or stick-like.

Comparing the effects of using and not using such a rotation operation, we found that when using the rotation method,
The processing time during which the resist on the wafer is removed is reduced. In other words, if we compare the rotation method with the same processing time without rotation, as shown in Figure 13, in the case of no rotation, the resist is removed in the center of the wafer, but the In the peripheral area, the remaining resist 40
There is a phenomenon in which a streaky pattern remains without being removed. Note that this was done for a 6# wafer.

For this reason, it can be said that the rotation process is effective in shortening the ashing process time, and is also effective in ashing the peripheral area of the wafer except for the central area. This is particularly effective for large-diameter wafers such as 6# to 10". In the case of Fig. 12(a), the gas injection part automatically rotates, so the equipment is simple. However, in the case of FIG. 12(b), the wafer mounting table 205 side is rotated, which makes the device somewhat complicated; This has the advantage that only a small amount of injection is required.

Next, detection of the end of ashing processing, which is related to overall control when performing single wafer processing, will be described.

As shown in FIG. 14, to complete the ashing process, a gas analyzer 7 is installed in front of the exhaust device 4.

Then, carbon dioxide (CO2) obtained from the gas analyzer 7 is
) A detection signal corresponding to m degrees is input to the end point determination/control device 8 to monitor the concentration of carbon dioxide, and when this concentration becomes zero or less than a predetermined value, it is determined that the ashing process has ended. do.

Here, the end point determination/control device 8 has an internal comparator and a controller composed of a microprocessor, and receives an ashing process end point detection signal from the comparator that receives the output of the gas analyzer 7, and performs the ashing process. Device 2. Gas introduction pipe (gas introduction pipe 20 in Figure 2)
2) and the lifting device 5 (motor 230 in FIG. 2).

That is, when the end point is detected, a signal is generated to close the valve of the gas introduction pipe, thereby controlling to stop the gas injection. At the same time, a lowering signal for the wafer mounting table 21 is sent to the elevating device 5, and this is controlled so that the gap between the diffusion plate and the wafer mounting table is widened (and the wafer mounting table 21 is lowered).
In the embodiment shown in FIG. 2, injection? Move T<) to the standby position.

C11. Upon receiving the standby position setting signal from the unloading device 5, the end point determination/control device 8 activates a gate valve (see FIG. 2) that communicates with the rotor/unloader section on the wafer unloading side (see loader/unloader 1s23b in FIG. 2). gate valve 2
25) is sent to the ashing device 2. Upon receiving this signal, the ashing device 2 opens its gate valve, and communicates the chamber (see chamber 29 in FIG. 2) with the rotor/unloader section on the wafer unloading side.

Next, the end point determination/control device 8 sends a signal to the ashing device 2 to operate the unloading side wafer handling mechanism (transfer arm 25b in FIG. 2).

Upon receiving this signal, the ashing device 2 releases the suction holding of the wafer 28, operates the wafer handling mechanism, and picks up the wafer 28 on the wafer mounting table 21 (see wafer mounting table 205 in FIG. 2). and remove it from the chamber. Then, the wafer is transferred to the belt transport mechanism (second
The receiver is transferred to the belt conveyor 'fR24b in the figure).

On the other hand, when the wafer handling mechanism on the unloading side completes unloading the wafer from the chamber, the ashing device 2
sends a completion signal to the end point determination/control device 8.

Upon receiving this completion signal, the end point determination/control device 8 sends a control signal to the ashing device 2 to close the gate valve (gate valve 225) communicating with the loader/unloader section on the wafer unloading side. , close the valve and disconnect the loader/unloader m< on the wafer unloading side.

Next, a control signal is sent to the ashing device 2 to release a valve (valve 224 in FIG. 2) communicating with the loader/unloader section on the wafer loading side (see loader/unloader ffi<23a in FIG. 2).

The ashing device 2 opens its valve and communicates the chamber with the loader/unloader section.

Next, the end point determination/control device 8 sends a signal to the ashing device 2 to operate the wafer handling mechanism on the carry-in side (transfer arm 25a in FIG. 2).

The ashing device 2 operates the wafer handling mechanism on the carry-in side, picks up the wafer 28 from the belt conveyance mechanism (see belt conveyance mechanism 24a in FIG. 2), and carries it into the chamber for unintentional processing. Place it on the mounting table 21 (Unino) (mounting table 205).

Then, the wafer mounting table 21 attracts and holds this.

When the wafer loading side r of the wafer handling mechanism on the loading side is completed and the arm and the like return to the loader/unloader, the ashing device 2 sends a loading completion signal to the end point determination/control device 8.

When the end point determination/control device 8 receives this signal, it sends a control signal to the lifting device 2 to close the valve communicating with the loader/unloader section on the wafer loading side, and also loads the wafer on the lifting device 5. The negative side of the mounting table 21 sends out a signal (in FIG. 2, a lowering signal of the injection unit 22).

The ashing device 2, which has received the control signal to close the valve, closes the valve and separates the chamber from the loader/unloader section 9 on the carry-in side. On the other hand, - of the wafer mounting table 21
The elevating device 5, which has received the L raising signal, controls the wafer mounting table 21 to set the gap between the diffusion plate and the wafer mounting table to a gear necessary for the reaction (set it to the reaction position).

At the time when the reaction position setting signal is received from the lifting device 5, the end point determination/control device 8 generates a signal to open the valve of the gas introduction pipe, and controls the start of gas injection. Then, exhaust gas is monitored and end point determination processing begins.

FIG. 15 is a graph showing changes in the concentration of carbon dioxide in the exhaust gas in this case.

As shown in the figure, the concentration of carbon dioxide gradually increases as the ashing processing time progresses and becomes a constant value. The ashing process is completed within 1 minute for the wafer, or within 1 to several minutes depending on the gap, wafer temperature, and gas flow rate, and the concentration rapidly approaches zero at this point. Go.

Therefore, the end point of the ashing process can be determined by comparing and detecting the carbon dioxide concentration with a comparator using a constant value of zero or close to zero as a reference.

By the way, the detected gas for the final determination is not limited to carbon dioxide, but water and carbon oxide have almost similar characteristics. Therefore, the end point of the ashing process may be determined by measuring the M of the gas.

On the other hand, as seen in this graph, the tendency for gas generation to begin to decrease after planting and then to zero is almost the same for exhaust gas. therefore,
By detecting the change point A of this characteristic or the point B where the characteristic decreases below a certain value, the end point r can be predicted.

The decreased point B can be detected by changing the reference value of the comparator, and the predicted road point T can be determined by adding a certain period of time to this detection point.

Further, the detection of the change point A can be easily realized by combining a differential circuit or a peak detection circuit with a comparator.

By the way, when detecting that the amount of exhaust gas is equal to or higher than a predetermined value, the gas analyzer 7 and the determination section of the end determination/control device 8 shown in FIG. 14 detect a specific gas amount f114. A detector (gas sensor) that detects the gas at a specific value or within a specific range, and an end point judgment circuit (judgment processing using a logic circuit, microprocessor, etc.) that judges the end point from the detection signal. Enough. On the other hand, when detecting the change point of exhaust gas, it is necessary to detect the change point of a specific gas. A measuring device or sensor that generates a signal corresponding to i as a detection signal, or a sensor that detects only the changing state is required.

As described above, in the embodiment, the diffusion plate is placed above the wafer, but this is because the wafer is placed on the side and is suspended, so that the diffusion plate side is placed above the wafer from below. It is also possible to adopt a configuration in which gas is blown into the air.
These may be arranged laterally with gaps at predetermined intervals.

In short, the arrangement relationship between these is not limited to "1" below, but it is sufficient that they face each other with a certain interval.

Moreover, any handling mechanism may be used to carry the wafer into and out of the ashing apparatus, and it is needless to say that the present invention is not limited to the embodiment.

In the embodiment, in order to carry in the wafer, either the wafer mounting table or the diffusion plate is relatively moved to ensure a space for inserting the handling arm.

However, they may also move up and down with their partner at the same time.

Furthermore, if a configuration is adopted in which the wafer is sent to the wafer mounting table using a belt transfer mechanism and a pusher, etc., the gap between the diffusion plate and the wafer mounting table can be narrow, and there is no need for an expanded space into which the handling arm, etc. described in 111j enters. Therefore, a mechanism for moving the wafer mounting table or the diffusion plate up and down is not essential.

The example describes the case of injecting gas, but this is! Alternatively, the ozone+oxygen gas may simply flow into the reaction space. Therefore, it is sufficient to have something that flows out at the funeral.

In addition, in the embodiment, the structure of the injection part is a conical one 9
There are cylindrical and tubular items listed, but for example, there are disc canes and nozzle-like items that emit ozone+.
The gas may be injected or flowed out, and various shapes can be applied.

Therefore, in this specification, the flat plate part includes a rod-shaped member whose locus forms an even flow of gas with the deck by rotating it.

The cooler should be adopted depending on the reaction conditions (although this is not necessarily the case.Also, the structure is based on the case where the refrigerant flows through the tube, but this does not apply to the case where the refrigerant flows directly to the injection part. A space with a heavy structure may be provided, and cooling may be performed using water, cooling air, various liquids or gases, or cooling metal using the Peltier effect or the like.

The diffusion plate uses a sintered alloy as having uniform porous pores, but porous materials are not limited to metals, and various materials such as ceramics can be used. Of course.

Furthermore, 1111 of the wafer during the ashing process
The higher the value, the faster the oxidation reaction rate will be, but this is also related to the wafer loading/unloading speed, and does not necessarily have to be set to a high value. moreover,
Considering the life time of ozone, the reaction can be carried out at about room temperature or at any other temperature. Furthermore, if the weight percent of ozone can be set to a high value, it is also possible to set the weight percent of ozone to a value even lower than room temperature. However, with current equipment, it is thought that the limit of ozone generation type ii)% is around 10 to 13%.

In the examples, the explanation focuses on resist as the object of ashing, but as mentioned in the prior art section, such ashing processing can be applied to various things such as removing ink and solvents, and can be used to remove oxidation. Any material may be used as long as it can be removed.

In addition, although the case where ozone is contained in oxygen gas is mentioned, it is not limited to oxygen, but also gases that do not react with ozone, especially N2. Various inert gases such as Ar, Ne, etc. can be used by containing ozone.

[Effects of the Invention] As can be understood from the above explanation, in this invention, a flow space through which a gas containing ozone flows is provided in contact with the wafer, and a film deposited on the wafer surface is subjected to a chemical reaction. The method measures the amount of a specific gas produced as a result of the chemical reaction, and detects the end point of the ashing process based on the change in the concentration of the specific gas. When proceeding to the ashing process, the end point of the ashing process can be detected based on a change in the concentration of a specific gas produced as a result of the chemical reaction. This makes it possible to shorten the transfer time, perform reliable ashing processing on each wafer, and realize high-speed single-wafer processing with little risk of damaging the wafers.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an ashing processing system according to an embodiment to which the ashing end point detection device of the present invention is applied, and FIG. FIGS. 3(a) and 3(b), which are cross-sectional explanatory diagrams showing the configuration, are specific explanatory diagrams of the electrostatic chuck in the wafer transfer mechanism, where (a) is the I-
I sectional view, (b) is a plan view thereof, FIG. 4 is an enlarged explanatory view of the reaction part, FIG. 5 (a) is a diagram explaining the relationship between reaction and movement by oxygen atom radicals, Figures (b) and (C) are diagrams each explaining the relationship between the diffusion opening and the ashing state of the wafer, and Figure 6 is a graph explaining the relationship between the decomposition half-life of ozone and the temperature of the diffusion opening. It is. In addition, Fig. 7 is a graph explaining the relationship between the surface temperature of the sea urchin I and the gas current at 300°C.
FIG. 9 is a graph illustrating the relationship between the ashing speed of the diffuser plate and the surface of Ueno 1 in C with respect to the gear knob.
Explanatory diagram showing the relationship between gas temperature and resist removal rate, Figure 1O (a), (b), (c), (d), (e), (f
) are an explanatory diagram of a specific example of the opening of the diffuser plate, and the 11th
Figures (a), (b), (c), and (d) are explanatory diagrams of specific examples of the gas cooling structure in the injection part, respectively, and Figure 12 (
a) is an explanatory diagram of the method of rotating the gas injection part, the 12th
Figure (b) is an explanatory diagram of rotating the sea urchin/N side, and Figure 13 is an explanatory diagram of the ashing effect when the sea urchin/N side is not rotated.
FIG. 4 is a block diagram of an embodiment of the ashing processing system that determines the end of the ashing process, and FIG. 15 is a graph of changes in the concentration of carbon dioxide in the exhaust gas.
FIG. 16 is a graph illustrating the relationship between the ashing rate and the ozone concentration, and FIG. 17 is a diagram illustrating the ashing effect of conventional ultraviolet rays. ■... Ashing system, 2.20... Ashing device, 3... Oxygen gas supply device, 3a... Gas flow regulator, 3b... Ozone generator,
3c...Oxygen supply source, 4...Exhaust device, 5...Elevating device, 6...Temperature controller, 7...Gas analyzer, 8
... End point determination/control device, 10a, 10b... Electrostatic chuck, Tsuk, 21... Wafer mounting table, 21a, 206... Heating device, 22.22a, 22b... Gas injection unit, 23a, 23
b...Loader/unloader section, 24a, 24b...
Belt conveyance mechanism section, 25a, 25b...transfer arm, 28a, 28b...suction chuck, 28...Unino A131...slit. Patent Applicant: Tokyo Electron Ltd. (Fig. 3), 7 11o1'2゜Fig. 4, Fig. 5] 2 67 Fig. 7.
+ (527m1n) Figure 8 Ward 9≠! 7 ρ1 屓 (0C) 箪1】鼎 (C) 12th [] (a) (b) Fig. 17 Fig. 13

Claims (4)

[Claims] (1) An ashing end point detection device in an ashing processing system in which a flow space through which a gas containing ozone flows is provided in contact with a wafer, and a film deposited on the wafer surface is oxidized and removed by a chemical reaction, An ashing end point detection device, characterized in that the ashing end point detection device determines the end point of the ashing process by detecting a change in concentration of a specific gas generated as a result of the chemical reaction. (2) The ashing processing system includes an ashing device,
The flow space in the ashing treatment system includes an exhaust device connected to the ashing device and a measuring device that measures the amount of a specific gas in the exhaust gas exhausted by the exhaust device, and the flow space in the ashing processing system is configured to discharge gas containing ozone. The concentration of a specific gas produced as a result of a chemical reaction is measured by the measuring instrument, and the change in the concentration is determined by the amount of the gas produced as a result of the chemical reaction. The ashing end point detecting device according to claim 1, characterized in that the ashing end point detecting device detects the ashing end point by decreasing from the value. (3) Claims characterized in that the facing arrangement is such that the outflow portion is at the top, and the specific gas produced as a result of the chemical reaction is carbon dioxide, the amount of which is measured by a gas analyzer. The ashing end point detection device according to item 2. (4) The ashing end point detection device according to claim 3, wherein at least one of the wafer and the outflow portion moves up and down.