JPH02201924A - Removal and cleaning of resist for substrate - Google Patents

Abstract

PURPOSE:To completely remove organic material by detecting the dry ashing end point through light irradiation on substrate surface and continuously carrying out dry over-ashing for at least half of the time required for the dry ashing for proceeding from the start to the end point. CONSTITUTION:The substrate surface W is irradiated with light 23, and the change of the interference waveform, between the reflected light 24 from the substrate surface and the reflected light 24 from a resist film surface, is detected, and the time, when the change of the interference waveform vanishes, is defined to be the dry ashing end point. Then, dry over-ashing is continuously carried out for at least half of the time required for the dry ashing for proceeding from the start to the end point. Thus, organic substance including residual organic material particles can be removed substantially completely.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is directed to a semiconductor wafer, a glass substrate, a ceramic substrate, etc. (in this specification, these are collectively referred to as "substrates"). The present invention relates to a resist removal cleaning method for a substrate, which decomposes and removes a resist film that is present on a substrate.

<Prior Art> Conventionally, for example, as described in Japanese Utility Model Application Publication No. 62-92641, a dry ashing chamber (anshing chamber) and a wet cleaning chamber are connected by a tubular passage, and this tubular A transport system for the substrate to be processed is installed in the passage, and the substrate is stored in an ashing chamber and the resist film on the substrate surface is ashed using oxygen plasma.Then, the unsealed substrate is passed through the tubular passage without being exposed to the outside air. The resist film is transported to a wet cleaning processing chamber by a transport system, and in this wet cleaning processing chamber, inorganic substances such as metal particles remaining in the resist film due to the ashing are washed away with a cleaning solution, and the remaining inorganic substances are also removed in the same manner. Clean and remove harmful substances such as arsenous acid with a detoxifying solution.
A dry-wet cleaning method is known in which the substrate is further washed with water and then dried with hot air and taken out to the outside.

<Problems to be Solved by the Invention> In the case of the above-mentioned conventional example, nothing is disclosed about detecting the end point of the dry ashing process in the ashing chamber.

If the dry ashing end point is detected too early, it will lead to insufficient ashing, and if it is detected too late, it will lead to excessive ashing.

Furthermore, in the conventional example described above, it is difficult to completely remove organic matter, and there is a high possibility that many fine organic matter particles remain.

Conventional methods for detecting the end point of dry ashing include: ■ Irradiating light onto the substrate, detecting changes in the interference waveform between the light reflected from the resist film surface and the light reflected from the substrate surface, and detecting the change in the interference waveform caused by the interference. A method of calculating the second and third derivatives of a waveform with a high frequency and determining the end point of dry ashing when the second and third derivatives become zero at the same time.
2), ■ In plasma ashing, the wavelength of 306 to 316 nm from OH (hydroxyl group molecules) in plasma
The light intensity of two or more spectral lines of the 2Σ/-2π transition light in the range of m is detected, and the rotational temperature of the plasma is calculated from the ratio of the two light intensities through processing such as logarithmic conversion.
A method for detecting excessive dry ashing based on changes in the rotational temperature (Japanese Patent Application Laid-Open No. 62-250644); A method using a Wheatstone bridge that converts a change in electrical resistance value into a change in voltage, and determining the end point of dry ashing when the voltage conversion becomes zero (Japanese Patent Laid-Open No. 63-21832
Publication No.), etc. are known.

However, none of these methods can accurately detect fine organic particles, and in addition, the method for detecting the end point of dry ashing is complicated, and not only are they expensive in terms of hardware and software, but they are also expensive compared to processing. This was a time-consuming and inefficient detection method.

An object of the present invention is to enable substantially complete removal of organic substances including organic particles, and to enable a simple method for detecting the end point of dry ashing, which is an indicator of the completion of organic substance removal. be.

Means for Solving the Problems> In order to achieve the above objects, the present invention has the following configuration.

That is, the first resist removal and cleaning method for a substrate of the present invention is to remove at least one of ozone supply, ultraviolet ray irradiation, or plasma irradiation to the surface of the substrate while rotating and heating the substrate. In the dry ashing process that decomposes and removes the resist film, the substrate surface is irradiated with light, and changes in the interference waveform between the light reflected from the substrate surface and the light reflected from the resist film surface are detected. The point at which it disappears is the end point of dry ashing.
The method is characterized in that dry overashing is continuously performed for at least half of the time required from the start of dry ashing to the end point of dry ashing.

Further, the second resist removal cleaning method for a substrate of the present invention includes detecting the end point of dry ashing by applying at least one of ozone supply, ultraviolet ray irradiation, or plasma irradiation to the surface of the substrate while rotating and heating the substrate. The first step is to decompose and remove the resist film on the substrate surface by performing the dry ashing process until the end of the dry ashing. a second step in which dry overashing is performed by continuing at least one step; and a third step in which residual organic matter on the substrate surface is cleaned by supplying an oxidizing cleaning liquid to the substrate surface while rotating the substrate after the second step; After the third step, a fourth step of cleaning the substrate surface by supplying a cleaning liquid to the substrate surface while rotating the substrate, and a fifth step of draining and drying the cleaning liquid on the substrate by rotating the substrate at high speed. It is characterized by including.

<Function> The function of the first substrate resist removal and cleaning method of the present invention is as follows.

By the time the end point of dry ashing is detected due to no change in the interference waveform of both reflected lights, most of the particles have been removed, but fine organic particles that cannot be detected due to changes in the interference waveform may be removed from the substrate surface. remains.

Therefore, it is necessary to continue dry ashing from the end point of dry ashing, but the question is how long it should continue.

According to the inventor's experiments, the organic particles remaining at the end point of dry ashing are reduced by the subsequent dry overashing. It was found that organic particles significantly decreased in the period up to /2, the reduction rate was small in the period exceeding T1/2 and up to T, and became stable with almost no decrease after T.

In other words, the remaining organic particles are almost completely removed within a period of time from T,/2 to T1 from the end point of dry ashing.

Therefore, the present invention makes it possible to substantially completely remove organic substances including residual organic particles by continuously performing overashing for at least half of the time T required from the start of dry ashing to the end point of dry ansing. That's what I did.

In addition, the method of detecting the end point of dry ashing based on the change in the interference waveform of both reflected lights and performing overashing for at least half the time required for this dry ashing is Detection methods based on the second and third derivatives of waveforms, 2Σ・-2
This is a simpler method than the detection method based on the plasma rotation temperature obtained through logarithmic conversion from the light intensity ratio of the spectral lines of the π-transition light, or the detection method using a semiconductor CO gas sensor or Wheatstone bridge (2).

Further, the effects of the second substrate resist removal and cleaning method of the present invention are as follows.

In the first step, when supplying ozone, irradiating ultraviolet rays, or irradiating plasma to the substrate surface, the substrate is heated, so that decomposition and removal of the resist film on the substrate surface is promoted. Further, since ozone supply, ultraviolet ray irradiation, or plasma irradiation is performed while rotating the substrate, the resist film is decomposed and removed uniformly over the entire surface of the substrate.

This first process is carried out until the end point of dry ashing is detected. At the end of the first process, most of the organic matter has been removed, but fine organic matter particles remain. Therefore, for the same reason as mentioned above, by continuing the same process as the first process for at least half of the time T required for the first process from the time when the end point of dry ashing is detected (dry overashing). , virtually completely removing organic particles.

In the next third step, organic matter including organic particles adhering to the substrate surface is cleaned with an oxidizing cleaning liquid supplied to the substrate surface while rotating the substrate, and then in the fourth step.
In the process, cleaning liquid is supplied to the substrate surface while rotating the substrate to wash away the oxidizing cleaning liquid, and in the fifth process, the substrate is rotated at high speed and the cleaning liquid on the substrate is blown off by centrifugal force, so that the substrate is quickly dried.

<Example> Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a flowchart showing the process of a resist removal and cleaning method for a substrate.

In step S1, a substrate made of semiconductor, glass, ceramic, or the like is carried into a dry cleaning device, and a resist film removal process is started.

In step S2, heating the substrate is started, and
Rotate the board. Turn on the first timer in step s3
L. In step S4, dry ashing is performed to decompose and remove organic matter on the surface of the substrate.

This dry ashing may be performed by irradiating the substrate surface with ultraviolet rays as in step 54-1, or by irradiating the substrate surface with ultraviolet rays as in step 54-1.
Ozone 03 may be supplied to the substrate surface as in step 54-3, or oxygen (02) and fluorocarbon (CF) may be turned into plasma and activated oxygen atoms etc. may be supplied to the substrate surface as in step 54-3. You can also supply it.

In the case of step 54-1, the wavelength of the ultraviolet rays is 180 to 35
0 nm, the substrate heating temperature is approximately 250° C., and the substrate rotation speed is 500 rpm or more. In the case of step 54-2, the ozone supply amount is approximately 1 ONf/min (N represents 1 atmosphere pressure),
Substrate heating temperature is approximately 250°C 1 substrate rotation speed is 50Qr
pm or more. In addition, in the case of step 54-3, the pressure in the processing chamber is reduced to 0.5 Torr or less, the supply amount of excited oxygen atoms is 1 Nl 1 minute, the substrate heating temperature is approximately 100° C., and the substrate rotation speed is 500 rpm or more. It is determined whether or not the end point of dry ashing has been detected, and if it has not been detected yet, the process returns to step S4 to continue dry ashing.

The method of detecting the end point of dry unsing is the 41st order ■, @
, O.

(2) Interference waveform method The substrate surface is irradiated with light of a wavelength (565 nm) that does not pass through the substrate, and changes in the interference waveform between the light reflected from the resist film surface and the light reflected from the substrate surface are detected. As the thickness of the resist film decreases as the resist film decomposes, the interference waveform changes. When the film thickness becomes substantially zero, there is no change in the interference waveform, so the time when the change disappears is the end point of dry ashing (see Figure 2).

@ In spectral plasma ashing, 1. Changes in the light intensity of specific wavelengths in the emission spectrum due to plasma reactions are detected, and the end point of dry ashing is when the changes disappear.

O-semiconductor CO gas sensor method detects the change in the concentration of CO gas in the dry ashing processing chamber, and the end point of dry ashing is when the change disappears.

The above steps 81 to S5 are the first process (dry unsing process) in the constitution of the invention. As a result of the above, most of the resist film on the surface of the substrate is decomposed and removed. However, at the end of this first process, a large number of fine organic particles remain on the substrate surface, which were not detected even by the detection of the end point of dry ashing in step S5.

When the end point of dry ashing is detected, the process proceeds to step S6, and the time T1 required from turning on the first timer in step S3 to detecting the end point of dry ashing is determined. Then, in step s7, the time limit T2 is set in advance as T2 =T+
The second timer set to /2 is ONL, and in step s8 the second timer is set to the time limit Tz (=T, /2
) is counted or not. If the counting is not completed yet, the process returns to step S4 and dry overashing is continued.

When the counting is completed, the process advances to step s9 to complete overashing.

To complete this process, not only the ultraviolet irradiation, the supply of oxygen, or the plasma irradiation is stopped, but also the rotation of the substrate is stopped.

The above steps 36 to S9 are the second process (dry overashing process) according to the structure of the invention. Through this second step, fine organic particles can be substantially completely decomposed and removed.

An example of the interference waveform in the period from step S4 to step S9 is shown in FIG. 2 (A) (in the case of T2-T, /2), and FIG. This shows the case where T2 is set to T, -T, and EP shows the end point of dry ashing.

The latter method can remove organic particles more completely, but it takes more time, so the time limit T2
How to set it shall be determined depending on the conditions in each case. However, T.

/2 to T1.

Next, in step SIO, the substrate is transferred from the dry cleaning device to the wet cleaning device. By spraying and supplying the oxidizing cleaning liquid to the substrate surface while rotating the substrate in step 311,
Cleans organic substances including fine organic particles remaining on the substrate surface.

This step Sll corresponds to the third process (wet organic substance cleaning process) in the constitution of the invention.

In addition, as the oxidizing cleaning liquid, for example, sulfuric acid (Hz S
op; 96%-t, 80°C) and hydrogen peroxide (HtO
A mixture of ammonium hydroxide (NH, ○H; 28% temperature, 80°C) and hydrogen peroxide (H
, ox ; 30%wt) and water (H! O), s
:tnia ratio, etc. can be mentioned. The substrate is rotated at 500 rpm and processed for 120 seconds.

Next, in step SL2, while rotating the substrate (100
The oxidizing cleaning solution is washed away by spraying and supplying pure water onto the substrate surface at a speed of 0 rpm) for 120 seconds. This corresponds to the fourth step in the structure of the invention. in this case,
Ultrasonic waves can be added if necessary.

Next, in step S13, the substrate is rotated at high speed (3000 rpm) for 30 seconds, and the pure water and cleaning solution on the substrate are blown off by centrifugal force. This corresponds to the fifth step (liquid draining drying; spin drying) in the structure of the invention. do. In this case, if necessary, the drying speed can be increased by irradiating with infrared rays.

It is also good to promote the evaporation of water by reducing the pressure.

Next, a cleaning apparatus for carrying out the method of this embodiment will be explained.

Figure 3 shows the board dry cleaning bag Wx and the wet cleaning device Y.
FIG.

First, the structure of the dry cleaning apparatus X that executes the first process and the second process will be described.

Inside the first processing chamber 1, there are a heater 2 that heats the semiconductor wafer W, and a plurality of lift rods (
A spin chuck 3 with a built-in (not shown) and a quartz ozone nozzle 5 with a built-in ultraviolet lamp 4 are installed inside.

The spin chuck 3 is configured to be horizontally rotated by a motor M1. A large number of ozone diffusion holes 5a are formed in the bottom plate of the ozone nozzle 5 in a uniform distribution state.

In order to increase the decomposition and removal efficiency of the resist film, it is preferable to make the distance between the wafer W on the spin chuck 3 and the ultraviolet lamp 4 as short as possible.

An inlet 1a and an outlet 1b for the wafer W are formed to face the peripheral wall of the first processing chamber 1 in the diametrical direction, and are slid up and down by a drive mechanism (not shown) to open and close the inlet 1a and the outlet 1b. Shutters 6a and 6b are provided.

On the outside of the first processing chamber l, there is a wafer transport mechanism 7a that carries the wafer W into the first processing chamber 1 through the loading port 1a, and a wafer transport mechanism 7a that carries the wafer W into the first processing chamber 1 through the loading port 1b.
and the second processing chamber 41 in the wet cleaning device Y.
A wafer transport mechanism 7b for transporting the wafer into the second processing chamber 41 and a wafer transport mechanism 70 for transporting the wafer from the second processing chamber 41 are provided.

These wafer transport mechanisms 7a, 7b, and 7c have the same structure, and are disclosed in, for example, Japanese Utility Model Application Publication No. 60-176548, and as shown in FIG.
The first arm 9 is attached to the rotating shaft of the motor 8, and the second arm 10 is rotatably attached to the free end of the first arm 9. It is composed of a transmission mechanism 11 that rotates the second arm 10, a vacuum chuck 12 formed at the free end of the second arm 10, and that sucks and holds the wafer W subjected to aX.

A supply pipe 15 of the ozone generator 14 connected to the oxygen cylinder 13 and a supply pipe 16 of the purging inert gas (N2) are each connected to the introduction pipe 5a of the ozone nozzle 5 via valves 17.18. ing.

Exhaust chamber 1 for gases such as ozone and CO, N20, etc. generated during decomposition and removal of resist film on the bottom plate of [1st processing chamber]
9 is formed, and an exhaust pipe 20 communicating therewith is connected to a blower (not shown).

The dry cleaning device X is provided with a dry ashing end point detection device 21 as shown in FIG.

This dry ashing end point detection device 21 includes a light emitting element 22
, an optical fiber 23 that guides the light from the light emitting element 22 to the surface of the wafer W, and an optical fiber 24 that guides the interference light between the reflected light from the surface of the substrate body of the wafer W and the reflected light from the resist film surface.
, a light receiving element 25 that inputs interference light from the optical fiber 24 and converts the interference waveform into a voltage waveform, an amplifier 26 that amplifies the output of the light receiving element 25, a high frequency removal filter 27, A.
/D converter 28 and a microcomputer 29, and the micro combinator 29 is composed of a CPU 30.
, ROM 31, and RAM 32, and is configured to determine the end point of dry ashing, count time T, , T, and motor M1.
Heater 2 UV lamp 4. Controls the shutters 6a, 6b, wafer transport mechanisms 7a, 7b, 7c, pulp 17, 18, etc.

Next, the structure of the wet cleaning device Y that executes the third to fifth steps will be described.

A wafer mounting table 42 installed in the second processing chamber 41 so as to be movable up and down is horizontally rotated by a motor M2. Bins 42a are provided upright on the wafer mounting table 42 at positions facing each other in the diametrical direction, and protrusions 42b for holding wafers are attached to the insides of the bins 42a.

A loading port 041a and a loading port 41b for the wafer W are formed to face the peripheral wall portion of the second processing chamber 41 in the diametrical direction, and are slid up and down by a drive mechanism (not shown).
1a, shanks 43a and 43b that open and close the outlet 41b
is set up.

The wafer transport mechanism 7b has the function of transporting the wafer W into the second processing chamber 41 through the transport port 41a, and also transports the wafer W from the second processing chamber 41 to the outside through the transport port 41b. 70 are provided.

The top plate of the second processing chamber 41 has a nozzle 44 that sprays an oxidizing cleaning liquid such as a mixture of H, So, and N20, or pure water.
is provided.

A drain and exhaust pipe 45 is connected to the bottom plate of the second processing chamber 41 .

Next, the operation of the dry cleaning device X will be explained.

In advance, the heater in the spin chuck 3 is energized to heat the spin chunk 3. Heating temperature is usually 200°C
The temperature is above 300°C.

The shank 6a is lowered to open the loading port 1a. The other outlet 1b is closed by a shutter 6b.

The wafer W is placed on the second arm 10 of the wafer transport mechanism 7a.
The wafer W is placed on R and held by vacuum suction from the vacuum chuck port 12. By driving the motor 8,
1st arm9. After displacing the second arm 10 and carrying the wafer W on the second arm 10 into the first processing chamber 1 through the loading port 1a and placing it in the spin chuck 3, the motor 8 is driven in the opposite direction. The second arm 10 is moved out of the loading port 1a, and then the shutter 6a is raised to close the loading port]a (the above corresponds to step S1).

Since the spin chuck 3 has already been heated to a predetermined temperature by the heater 2, the wafer W starts to be heated immediately after being transferred to the spin chunk 3. As a result, the resist film on the surface of the wafer W begins to thermally decompose. This thermal decomposition of the resist film promotes decomposition and removal of the resist film in the next step.

Next, after the wafer W is attracted and held on the spin chuck 3 by vacuum suction, the wafer W is rotated together with the spin chuck 3 by driving the motor M1 (the above corresponds to step S2).

Then, the pulp is opened, oxygen is supplied from the oxygen cylinder 13 to the ozone generator 14, and the ozone generator 14 is turned on to convert the supplied oxygen into ozone.
A required flow rate of ozone is supplied to the surface of the wafer W in the first processing chamber 1 via the introduction pipe 5a and the ozone diffusion hole 5a of the ozone nozzle 5.

At the same time as this ozone supply, a blower (not shown) is driven to exhaust the exhaust pipe 2.
0, the exhaust chamber 19 is brought to negative pressure via the first processing chamber 1.
This prevents ozone from accidentally leaking into the room from inside (the above corresponds to step 54-2).

In addition, in parallel with ozone supply, the ultraviolet lamp 4 may be turned on to irradiate the surface of the rotating wafer W with ultraviolet rays (step S4-1).

Ozone O8 decomposes the organic matter forming the resist film on the surface of the wafer W, converts it into Cot, HzO, etc., and separates and removes it from the wafer W. The generated CO□, H,
Gases such as O are exhausted to the outside through the exhaust pipe 20. Heating the wafer W by the heater 2 promotes decomposition of organic matter. Note that when ultraviolet irradiation (step S4-1) is used in combination, the ozone 03 is decomposed by the ultraviolet rays into activated oxygen atoms, and the organic substances are oxidized by the oxygen atoms, so that the decomposition of the organic substances is further promoted.

Since ozone is supplied while rotating the wafer W, or ultraviolet rays are irradiated along with the ozone supply, it is possible to uniformly remove organic substances over the entire surface of the wafer W.

As described above, the resist film is gradually decomposed and removed, and most of the organic matter on the surface of the wafer W is decomposed and removed, but many fine organic matter particles remain on the surface of the wafer W.

During this time, the dry ashing end point detection device 21 detects, for example, a change in the interference waveform, and the CPU 30 determines whether or not the change has disappeared. The time T required to reach the ashing end point is stored in RAM3.
2, and the CPU 30 calculates the dry overashing time T, = T1/2, which is also stored in the RAM 32.
(The above corresponds to steps S5 and S6).

Then, until the overashing time T2 elapses,
Continue to perform dry ashing (overashing) as described above. And overashing time T
, the CPU 30 stops overashing. That is, the ozone generator 14 is turned off and the pulp 17 is closed. If ultraviolet irradiation is also being used, the power to the Shikusen lamp 4 is turned off. This results in substantially complete decomposition and removal of organic matter including fine organic matter particles.

Note that the heater 2 continues to be energized.

The pulp 18 is then opened and the supply tube 16. A required flow rate of inert gas is supplied to the ozone nozzle 5 via the introduction pipe 5a.

This inert gas flows into the first processing chamber 1 through the ozone diffusion hole 5a, and the ozone remaining in the first processing chamber 1, the COR, H, Gas such as O is purged outside the room through the exhaust pipe 20. Next, the motor M is stopped to stop the rotation of the wafer W (the above corresponds to steps 37 to S9).

Next, the negative pressure applied to the spin chuck 3 is released,
The suction hold on the wafer W is released.

Then, the lifter rod is raised to receive and pick up the wafer W at its tip, the shutter 6b is lowered to open the carry-out port 1b, the wafer W is taken out from the first processing chamber 1 by the wafer transport mechanism 7b, and the wafer W is transferred to the wet cleaning device. Y's second processing chamber 4
Insert into 1. Thereafter, the shutter 6b is raised to close the outlet 1b.

Following the dry cleaning process in the dry cleaning device X described above, the wet cleaning process in the wet cleaning device Y begins.

That is, the shutter 43a is lowered to open the entrance 41a. The other outlet 41b is closed by a shutter 43b.

The second wafer transferred from the dry cleaning device
The wafer W held by the arm 10 is carried into the second processing chamber 41 through the carry-in port 41a, and then placed on the wafer mounting table 42.
The motor 8 is stopped at the timing when the wafer W is directly above the wafer W.

The wafer mounting table 42 is raised to position the wafer W inside the bin 42a. Then, the vacuum suction from the vacuum chuck port 12 is released, and the wafer W is removed from the protrusion 42.
Uke is taken with b.

After the second arm 10 is exited from the loading port 41a, the shutter 43a is raised to close the loading port 41a (as described above,
(equivalent to step SIO).

While rotating the wafer W by rotating the wafer mounting table 42, a mixed solution of H, S04 and H20□ as an oxidizing cleaning solution is sprayed and supplied from the nozzle 44 toward the surface of the wafer W, thereby cleaning the wafer W. Organic matter including organic matter particles remaining on the surface is removed (the above corresponds to step Sll).

By spraying and supplying pure water from the nozzle 44 toward the surface of the wafer W while the rotation of the wafer W continues, the mixed liquid and unnecessary substances remaining on the surface of the wafer W are cleaned and removed ( (equivalent to step S12).

In addition, in this cleaning process, if necessary, an ultrasonic vibrator may be attached to the nozzle, and ultrasonic waves with a frequency of 800 kl (Z or higher) may be added to the pure water to increase the cleaning efficiency. .

Then, a large centrifugal force is exerted on the wafer W on the wafer mounting table 42 by high-speed rotation of the motor M2, and the oxidizing cleaning liquid and pure water adhering to the surface of the wafer W are blown off (corresponding to step S13).

In this spin drying process, it is preferable to accelerate the drying speed by emitting infrared rays from a drying infrared lamp, especially in the 1200 nm wavelength range that is easily absorbed by silicon wafers, or by reducing the pressure in the second processing chamber 41. .

In addition, in the wet cleaning apparatus Y, the wafer mounting table 42
The wafer W may be held by the pins 42a and the protrusions 42b, or by vacuum suction.

±Kugami 拮且■ Regarding a 6-inch wafer having a resist film with a thickness of 1.5 μm, fine organic particles (thickness of 0.28 μm or more; the same applies hereinafter) in its initial state (before ashing treatment). When I checked the number, there were 7.

Wafer heating temperature 250°C1 Ozone supply amount 1ONffi
Ozone ashing was performed under the conditions of /min, and the wavelength was 565 nm.
When the dry ashing end point was detected using an interference waveform method using light, it took T, = 108 seconds to detect it. The number of organic particles at this time was 230, an increase of 223 from the initial state.

Next, without performing overashing, which is the gist of the present invention, wet cleaning was performed by spraying a mixed solution of NH, OH and H, O□ as an oxidizing cleaning solution, cleaning with pure water, and spin drying. , the number of organic particles is 181
This was a decrease of 49 pieces from the end point of dry ashing.

The important point here is the number of organic particles that decreased between the start of wet cleaning with the oxidizing cleaning solution and the spin drying, and this is expressed as P, which in this case is P=49. Since overashing is not performed, it can be said that the decrease in the number of pieces is small.

■ When ozone ashing was performed under the same conditions as above on a wafer with the same size and film thickness as above and 9 organic particles in the initial state, it took T+ = 108 seconds to reach the end point of dry ashing. When overashing was further continued for T,=T,/2=54 seconds, the number of organic particles was 150.

Next, wet cleaning → pure water cleaning → spin drying was performed under the same conditions as above, and as a result, the number of organic particles was 50, and the number decreased by wet cleaning was Pm2O3.

■ When ozone ashing was performed under the same conditions as above on a wafer with the same size and film thickness as above and 10 organic particles in the initial state, it took T, = 107 seconds to reach the end point of dry ashing. However, when overashing was further continued for T,=T,=107 seconds, the number of organic particles was 120.

Next, wet cleaning → pure water cleaning → spin drying was performed under the same conditions as above, and as a result, the number of organic particles was 40, and the number decreased by wet cleaning was P=80.

Comparing the cases (1) and (2) in which overashing was performed and the case (2) in which overashing was not performed, it can be seen that the effect of reducing organic particles by overashing is large.

In ■, the number of organic particles at the end of dry ashing is 230, in ■, the number of organic particles after 50% overashing is 150, and in ■, 10
The number of organic particles after 0% overashing is 120. The results are shown in FIG.

It is clear that overashing reduces organic particles, but overashing is 50%
If it is less than 50%, the reduction effect is not sufficient.
When it is 100%, the reduction effect is large.

Although the number of organic particles changes depending on the initial conditions of the wafer and resist film, the number of processed wafers, etc., the tendency shown in FIG. 6 is almost the same.

<Effects of the Invention> According to the first substrate resist removal and cleaning method of the present invention,
The end point of dry ashing can be detected using the conventional detection method (■) based on the second and third derivatives of the high-frequency waveform, or from the light intensity ratio of the spectral lines of the 2Σ/-2π transition light (■). Compared to the detection method based on the plasma rotation temperature determined through logarithmic conversion or the detection method using a semiconductor CO gas sensor or Wheatstone bridge described in (2), it can be performed based on a simple change in the interference waveform, and moreover,
By performing overashing for at least half the time required from the start of dry ashing to the end point of dry ashing, fine organic particles that cannot be detected by the interference waveform method described above can be almost completely removed.

Further, according to the second substrate resist removal and cleaning method of the present invention, ozone is supplied to the substrate surface in the first step.

When performing ultraviolet irradiation or plasma irradiation, the decomposition of organic matter can be promoted by heating the substrate, and the decomposition can be made uniform by the substrate process.

The effect of overashing in the second process is as described above. The cleaning of organic matter including organic particles with the oxidizing cleaning solution in the third step, the cleaning of the oxidizing cleaning solution with the cleaning solution in the fourth step, and the spin drying in the fifth step substantially completely removes the organic matter including organic particles. Moreover, it can be done efficiently.

[Brief explanation of the drawing]

1 to 6 relate to embodiments of the present invention, in which FIG. 1 is a flowchart showing an example of the process of a resist removal cleaning method for a substrate, FIG. 2 is a graph showing how the interference waveform changes, and FIG. The figure is a schematic block diagram of a dry cleaning device and dry cleaning device that implements the present invention, FIG. 4 is a schematic block diagram of a wafer transfer device, FIG. 5 is a block diagram of a dry ashing end point detection device, and FIG. 6 is a block diagram of an overashing device. 12 is a graph showing how organic particles are reduced by. W... Wafer (substrate) X... Dry cleaning device Y... Wet cleaning device 1... First processing chamber 2... Heater 4... Ultraviolet lamp 5... Ozone nozzle 14...・Ozone generator 21...Dry ashing end point detection device 22...Light emitting element 25...Light receiving element 41...Second processing chamber 42...Wafer mounting table 44...Nozzle applicant Dainippon Screen Manufacturing Co., Ltd. Representative Patent Attorney Tsutomu Sugitani Figure 7a (7b, 7c) Figure 111 豐λ-BA'-ASSIN 7゛C01,) □Haruma (minute)

Claims (2)

[Claims] (1) In the dry ashing process, the resist film on the substrate surface is decomposed and removed by supplying ozone, ultraviolet rays, or plasma irradiation to the surface of the substrate while rotating and heating the substrate. Light is irradiated onto the surface, and changes in the interference waveform between the light reflected from the substrate surface and the light reflected from the resist film surface are detected.The point at which the interference waveform no longer changes is defined as the end point of dry ashing, and the process starts from the start of dry ashing. A resist removal cleaning method for a substrate, characterized in that dry overashing is continuously performed for at least half the time required to reach the end point of dry ashing. (2) Decompose and remove the resist film on the substrate surface by supplying ozone, UV irradiation, or plasma irradiation to the surface of the substrate while rotating and heating it until the end point of dry ashing is detected. In the first step, from the time when the end point of dry ashing is detected, dry overashing is performed by continuing at least one of ozone supply, ultraviolet irradiation, or plasma irradiation for at least half the time required for the first step. a second step; a third step of cleaning residual organic matter on the substrate surface by supplying an oxidizing cleaning liquid to the substrate surface while rotating the substrate after the second step; a fourth step of cleaning the substrate surface by supplying a cleaning liquid to the substrate surface, and a fifth step of draining and drying the cleaning liquid on the substrate by rotating the substrate at high speed. Method.