JP3402932B2 - Cleaning method and apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning method and apparatus for cleaning a substrate to be processed.

[0002]

2. Description of the Related Art Generally, in a manufacturing process of a semiconductor wafer (hereinafter referred to as "wafer") or a liquid crystal display (LCD) substrate, particles adhering to the surface of a substrate to be processed or a natural oxide film formed by contact with the atmosphere are removed. A cleaning step is performed to remove. There are a batch type and a single-wafer type as an apparatus for cleaning the substrate to be processed, and a spin-type apparatus is generally known as a single-wafer type cleaning apparatus.

In this spin type cleaning apparatus, a substrate to be processed is held on a spin chuck and rotated, for example, a chemical liquid is supplied to the surface of the substrate to be processed, pure water is then supplied, and then spin drying is performed. There is. Then, in the step of drying the substrate to be processed, in addition to blowing pure water off by spin, an inert gas or clean air is also sprayed on the surface of the substrate to be processed to accelerate the drying.

[0004]

By the way, as an index of the drying performance of a substrate to be processed, it is possible to say how many "water marks" due to poor drying, which are usually called watermarks, are generated. Therefore, the generation of watermarks was unavoidable. FIG. 15 is a diagram schematically showing how a watermark is formed on the surface of the wafer W when the surface of the wafer W is treated with hydrofluoric acid, for example. First, while holding the wafer W on the chuck 11 and rotating the wafer W, a hydrofluoric acid solution is supplied to the surface of the wafer W from the nozzle 12 as shown in FIG. 15A, and then pure water is supplied from the nozzle 13 as shown in FIG. 15B. Water is supplied to rinse the surface, and pure water is blown off by centrifugal force. At this time, part of the pure water remains on the surface of the wafer as shown in FIG. 7C, and remains as a watermark 14 as shown in FIG.

The cause of such a watermark is considered as follows. That is, as the water dries, it becomes spherical at the end and remains on the wafer surface due to surface tension, and the water, oxygen in the air, and silicon on the wafer surface react as in the following formula (1) to generate H ₂ SiO ₃ is produced and the reaction product is deposited, or a very small amount of silica (SiO ₂ ) contained in pure water is deposited to form particles. Si + H ₂ O + O ₂ → H ₂ SiO ₃ (1)

Particularly in the case of hydrofluoric acid treatment, S on the wafer surface is
Since iO ₂ is removed and Si is exposed, the reaction of the above formula (1) is likely to occur. Further, as shown in FIGS. 16A and 16B, when the surface of the wafer W has a concave portion made of a hydrophobic film such as polysilicon, the water tends to be spherical and remain, which makes it difficult for the water to fly, and It becomes easier to remain as.

However, as the line width of the semiconductor device becomes finer, the tolerance of particle contamination becomes very strict, and there is a problem that the yield decreases if the watermark remains on the surface of the substrate to be processed. .

The present invention has been made under such circumstances, and an object thereof is to make a surface of a substrate to be processed highly clean after cleaning the surface of the substrate, thereby generating a watermark. An object of the present invention is to provide a cleaning method and an apparatus therefor capable of suppressing the above.

According to the present invention, a step of supplying a cleaning liquid to the surface of the substrate to be cleaned while the substrate to be processed is placed and rotated on the rotary mounting part, and subsequently the substrate to be processed is rotated. , A step of supplying a replacement medium liquid to the surface of the substrate to be processed during the supply of the cleaning liquid to replace the cleaning liquid with the replacement medium liquid, and then rotating the substrate to be processed while the surface of the substrate to be processed is rotated. A step of removing the displacement medium liquid by centrifugal force due to rotation, wherein the displacement medium liquid is miscible with the cleaning liquid and has a surface tension smaller than that of the cleaning liquid. Here, prior to the step of supplying the cleaning liquid to the surface of the substrate to be cleaned and cleaning the substrate, the chemical liquid is supplied to the surface of the substrate to be processed while the substrate to be processed is placed and rotated on the rotary mounting part. You may make it implement the process which does.

[0010] substitution medium solution is desirably fed per second 80cm following speed. Further, in the step of removing the replacement medium liquid on the surface of the substrate to be processed, the substrate to be processed is rotated at a first rotation speed, and subsequently, higher than the first rotation speed, for example, 2
It is desirable to perform it while rotating the substrate to be processed at the second rotation speed of 000 rpm or more, and it may be performed under reduced pressure.

According to the present invention, the substitution medium vapor is supplied to the surface of the substrate to be processed, and the substitution medium vapor is condensed or adsorbed in the cleaning liquid to condense the substitution medium vapor into a liquid state, and the cleaning liquid is substituted with the substitution medium liquid. You may do it. At this time, the displacement medium vapor is preferably at a temperature equal to or higher than the temperature of the cleaning liquid. Further, it is preferable that the supply position of the substitution medium vapor on the substrate to be processed is scanned from the central portion of the surface toward the outside.

Further, the present invention is an apparatus for supplying a cleaning liquid to the surface of a substrate to be cleaned while placing the substrate to be processed on a rotary mounting portion and rotating the substrate, wherein the cleaning liquid is applied to the surface of the substrate to be processed. A cleaning liquid supply unit for supplying the replacement medium fluid supply unit for supplying a replacement medium fluid that is compatible with the cleaning liquid and has a smaller surface tension than the cleaning liquid to the surface of the substrate to be processed; And a control unit for switching the supply of the cleaning liquid to the surface to the supply of the replacement medium fluid.

Here, the rotary mounting portion is provided with a first clamp portion and a second clamp portion for engaging with a side portion of the substrate to be processed and holding the substrate, and When supplying the replacement medium fluid, the substrate to be processed may be held by the first clamp portion, and after the replacement medium fluid is supplied, the substrate to be processed may be held by the second clamp portion. The replacement medium fluid supply unit is for supplying the replacement medium liquid, and the discharge unit faces the center of the substrate to be processed and is a nozzle having a diameter of 4 mm or more. It is desirable that the distance between the ejection portion of the displacement medium fluid supply unit and the surface of the substrate to be processed when supplying to the surface of the substrate to be processed is 2 cm or less.

In the present invention, when a cleaning liquid such as pure water is supplied to the surface of the substrate to be processed, and then the substitution medium is supplied as a solution or vapor to the surface of the substrate to be processed, the pure water is dissolved in the organic solvent, Pure water on the substrate to be processed is completely replaced by the replacement medium. For this reason, pure water is removed from the surface of the substrate to be treated without being left in a spherical shape and is promptly removed. For example, the precipitation of silica in the pure water and the precipitation of reaction products do not substantially occur, thus reducing the generation of particles. it can.

[0015]

1 is a schematic plan view showing an entire cleaning station including a cleaning device according to a first embodiment of the present invention. In this cleaning station, a wafer loading / unloading port 21 on which a cassette C containing, for example, 25 wafers W is placed from the outside, a transfer arm 22 movable in X, Y, and θ directions, and X, Y, and θ. , Main arm 23 movable in the Z (height) direction.
The back surface cleaning unit 25 and the cleaning / drying unit 2 along the transport path 24 of
6, the APM processing unit 27, the HPM processing unit 28, and the hydrofluoric acid processing unit 29, which is the cleaning device according to the first embodiment of the present invention, are arranged.

In the cleaning station, the wafer W in the cassette C carried into the carry-in / carry-out port 21 is transferred to the main arm 23 via the transfer arm 22 and sequentially transferred to each processing section. That is, for the wafer W, the back surface of the wafer W is first cleaned in the back surface cleaning unit 25 with, for example, pure water.
Next, in the APM processing unit 27, the APM solution (ammonia +
Particles are removed with hydrogen peroxide water + pure water). The APM-processed wafer W is subsequently cleaned of metal contamination by an HPM solution (hydrochloric acid + hydrogen peroxide solution + pure water) in the HPM processing section 28, and then the hydrofluoric acid processing section 29.
The natural oxide film is removed with a hydrofluoric acid solution, and the product is roughly washed with water and finally washed with pure water in the washing / drying unit and finally dried. The APM processing unit 27 and the HPM processing unit 28 are also washed with water and dried.

Next, the hydrofluoric acid treatment unit 29 corresponding to the cleaning apparatus according to the first embodiment of the present invention, which is provided in the cleaning station, will be described in detail. 2 and 3
FIG. 3A is a vertical cross-sectional side view and a plan view showing a main part of a cleaning device (hydrofluoric acid treatment unit). This cleaning apparatus includes a rotary mounting unit 3 that holds a wafer W and rotates on a horizontal plane in an airtight processing chamber 30 that can be set to a reduced pressure atmosphere. The rotary mounting unit 3 is a motor or the like. The rotation mechanism 31 including a rotation plate 33 provided above the rotation shaft 32 that rotates around a vertical axis, and the wafer W is floated from the rotation plate 33 by being provided around the rotation plate 33 and the periphery of the rotation plate 33. And a mechanical chuck holding portion 34 that holds the peripheral portion of the wafer W in this state. This mechanical chuck holder 34
As shown in FIG. 3 (a), a part of the wafer W in the circumferential direction is cut out so that the wafer W can be transferred to and from the main arm 23.

Further, the mechanical chuck holding portion 34 is formed with notches 34a at, for example, six positions in the circumferential direction, and the notches 34a are clamp fingers 38a which are first clamp portions and second clamp portions 38a. Clamp finger 3 which is
And 8b are provided. These clamp fingers 38a, 3
8b holds the wafer W in contact with the side surface of the wafer W, and is configured to be movable between this fixed position and the retracted position below the support level of the mechanical chuck holding portion 34. The three clamp fingers 38a form one group and cooperate to hold the wafer W, and the other three clamp fingers 38b form one group and cooperate to hold the wafer W. The clamp fingers 38a and 38b belonging to the respective groups are driven by drive mechanisms 39a and 39b supported by the rotary plate 33, respectively, and these spin the wafer W as described later. It is used by switching during drying.

A double cup composed of an inner cup 4 and an outer cup 5 is provided around the rotary mounting portion 3 so as to surround the rotary mounting portion 3. The double cup can be moved up and down by an elevating portion 35. It is configured. The inner cup 4 and the outer cup 5 are for receiving and discharging the liquid that the wafer W has rotated and scattered, and the receiving port 51 of the outer cup 5 is the inner cup 4.
It is formed so as to be located above the receptacle 41 of the.

The inner cup 4 and the outer cup 5 are constructed such that the atmosphere inside the cup is exhausted by a common exhaust passage 36 on the lower side, and the inner cup 4 and the outer cup 5 are also arranged.
Drain pipes 42 and 52 are provided at the bottoms of the respective pipes. Further, a receiving cup 37 is provided so as to surround the inner side of the inner cup 4, that is, the lower region of the rotary mounting portion 3, and the liquid accumulated in the receiving cup 37 is discharged through the drain pipe 42. Has become. The reason why the cup is duplicated inside and outside is to collect the chemical solution and the cleaning solution separately.

The above-mentioned cleaning apparatus includes a chemical solution nozzle 6 which is a chemical solution supply section for supplying a chemical solution such as a 0.5% hydrofluoric acid solution to the surface of the wafer W, and a cleaning solution supply section for supplying a cleaning solution such as pure water. A pure water nozzle 7 and a replacement medium such as isopropyl alcohol (hereinafter referred to as "IPA")
A replacement medium nozzle 8 which is a replacement medium fluid supply unit for supplying an organic solvent such as The displacement medium is miscible with the rinse liquid, has a smaller surface tension than the rinse liquid, and is volatile, for example, 10 mmHg to 2 at 20 ° C.
It is desirable to have a vapor pressure of 00 mmHg. For example, when the rinse liquid is pure water or a liquid having properties close to those of pure water, a hydrophilic substance such as IPA, acetone, or methanol can be used as the replacement medium.

The nozzles 6, 7 and 8 are respectively inserted into three rotary shafts 61, 71 and 81 vertically provided outside the double cup with a circumferential interval. The rotating shafts 61, 71, 81 extend from the upper ends of the rotating shafts 61, 71, 81, and are bent so that their tip ends face the vicinity of the center of the wafer W.
In addition, the vicinity of the tips of the nozzles 6, 7 and 8 are respectively connected to the rotary shaft 6
Arms 62, 72, 8 extending horizontally from 1, 71, 81
Fixed by 2 respectively.

The rotating shafts 61, 71 and 81 are rotating mechanisms 6 respectively.
3, 73, 83 for rotating about the vertical axis to rotate the nozzles 6, 7, 8 between a supply position where the tip end faces the wafer W and a retracted position outside the outer cup. Is. The tip of the cleaning liquid nozzle 7 is the wafer W.
The wafer W is located at a location slightly away from the center
It extends obliquely so as to supply pure water toward the central portion, and the tip of the replacement medium nozzle 8 faces the central portion of the wafer W so as to be substantially perpendicular to the surface of the wafer W. (See Figure 4).

The base end sides of the nozzles 6, 7 and 8 are shown in FIG.
As shown in FIG. 5, they are connected to a hydrofluoric acid solution supply source, a pure water supply source and an IPA supply source, which are not shown, via valves 64, 74 and 84, respectively. As shown in FIG. 4, the cleaning device also includes a control unit 9, which controls the rotating mechanism 6 according to a predetermined program stored in advance in the memory unit.
It has a function of controlling the valves 3, 73, 83 and the valves 64, 74, 84.

Next, an embodiment of a cleaning method performed by using the above-mentioned cleaning device will be described. First, the wafer W is shown in FIG.
The wafer W is held by the clamp fingers 38a after being mounted on the rotary mounting unit 3 in the cleaning device (hydrofluoric acid processing unit) 29, specifically, the mechanical chuck holding unit 34 by the main arm 23 shown in FIG. Next, the rotary mounting unit 3 is rotated by the rotating mechanism 31 at a rotation speed of, for example, 300 rpm, and the nozzle 6 is rotated from the standby position to the supply position (the position where the tip end faces the center of the wafer W), and the valve 64
Is opened and, as shown in FIG. 5A, a 0.5% hydrofluoric acid solution 60, for example, is supplied from the nozzle 6 to the vicinity of the central portion of the surface of the wafer W for 1 minute at a flow rate of 1000 ml / min.
Thus, the natural oxide film on the surface of the wafer W is removed.

At this time, the double cup is placed so that the receiving opening 41 of the inner cup 4 faces the peripheral edge of the wafer W (the position shown in FIG. 2), and the inside of the exhaust passage 36 is exhausted by an exhaust means (not shown). Since it has been evacuated, the hydrofluoric acid solution that has been repelled from the surface of the wafer W is sucked into the inner cup 4 through the receiving port 41 and collected via the drain pipe 42.
Thereafter, the chemical solution nozzle 6 is retracted to the retracted position, the pure water nozzle 7 and the replacement medium nozzle 8 are rotated to the supply position (the position where the tip end faces the center of the wafer W), and the valve 74
Then, as shown in FIG. 5B, pure water 70 is supplied from the nozzle 7 to the vicinity of the central portion of the surface of the wafer W for 1 minute at a flow rate of, for example, 1000 ml / min to rinse the surface of the wafer W. At this time, the double cup is lowered by the elevating part 35 and placed so that the receiving port 51 of the outer cup 5 faces the peripheral edge of the wafer W, and the pure water blown off from the surface of the wafer W is outside the receiving port 51. It is sucked into the cup 5 and discharged through the drain pipe 52.

Here, the supply of the pure water 70 is stopped, that is, the valve 74 is closed, for example, two to three seconds before the valve 84 is opened, and as shown in FIG. A displacement medium liquid such as IPA liquid 80 is supplied for 10 seconds at a flow rate of, for example, 500 ml / min. The wafer W is rotated at a rotation speed of 300 rpm from the supply of the hydrofluoric acid solution to the supply of the IPA liquid, and after the supply of the IPA liquid is stopped, the wafer W is rotated at the rotation speed for, for example, 1 second, and then at 3000 rpm for 4 seconds. 5000 for 5 seconds after that
The IPA solution is removed by rotating at rpm as shown in FIG. 5 (d). Such a series of processing is performed based on the program in the control unit 9.

At this time, at the high speed rotation of 3000 to 5000 rpm, as shown in FIG. 3B, the clamp fingers 38a to 38a holding the wafer W until now are held.
It is desirable to switch to b and hold the wafer W by the clamp fingers 38b. When the group of the clamp fingers that hold the wafer W is switched from 38a to 38b in this way, the holding portions of the wafer W are different between the clamp fingers 38a and 38b, so that the contact portion between the clamp fingers 38a and the wafer W is different. The wafer W is held by the clamp fingers 38b to be exposed, and the IPA liquid remaining in this portion is removed, which makes it difficult to form a watermark in this portion.

After the pure water 70 is replaced with the IPA liquid 80, the inside of the processing chamber 2 may be depressurized to a predetermined vapor pressure, for example, the vapor pressure of the substitution medium (60 mmHg at 30 ° C. in IPA). An inert gas such as N ₂ gas may be blown onto the surface of the wafer W during drying. By performing these auxiliary operations, the replacement medium can be removed in a shorter time, and the cleaning time can be shortened.

According to the above-described embodiment, since the IPA liquid is supplied after the pure water is supplied to the surface of the wafer W, the IPA liquid is dissolved in the pure water on the surface of the wafer W. And IPA
Since the surface tension of the liquid is smaller than that of pure water, the mixing property with pure water is good, and the wettability with the substrate is good, the supplied liquid I
The PA liquid is completely replaced with pure water. The IPA liquid thus replaced is removed by centrifugal force, whereby pure water is promptly removed from the surface of the wafer W. As a result, the generation of so-called watermarks due to the precipitation of reaction products of water, oxygen in the air and silicon, the precipitation of silica contained in water, etc. is prevented, the generation of particles is reduced, and the IPA liquid contains impurities. Since it is not included, the yield is improved. Note that the IPA liquid does not substantially contain impurities, but even if it contains a trace amount of impurities, the IPA liquid is removed by centrifugal force, so that there is little possibility that a watermark will be generated.

In this case, if there is a blank time after the supply of the pure water is stopped and before the supply of the IPA liquid is started, water particles will be formed and a watermark will be generated. It is preferable to perform the supply of the IPA liquid and the supply of the IPA liquid by overlapping, but the IPA liquid may be supplied without interruption after the supply of pure water is stopped. Further, the nozzle for supplying pure water and the nozzle for supplying the IPA liquid may be shared. For example, when one common nozzle that is both a cleaning liquid supply unit and an organic solvent supply unit is used, a valve of the pure water supply passage It is preferable to open the valve of the IPA liquid supply passage before closing the above because the blank time is eliminated. Further IP
In parallel with the supply of liquid A or the rotary drying, dry air or N
₂ gas or the like may be sprayed onto the wafer surface to suppress the generation of watermarks and accelerate the removal of the IPA liquid.

Here, hydrofluoric acid treatment was performed by the method described in the above-mentioned embodiment, followed by washing by successively supplying pure water and IPA liquid, and then spin drying (flow rate of each liquid and The supply time and the number of rotations of the wafer are the same as those described above.) As shown in FIG. 6A, no watermark was found on the wafer surface. For the evaluation of the generation of the watermark, a square area of 1 cm x 1 cm was defined as shown on the surface of the 6-inch wafer, and each area was visually observed with a microscope with a magnification of 150 times.
This was done by counting the number of watermarks.

As a comparative example, in the above-mentioned method, I
The same evaluation was performed when the PA liquid was not supplied, and when the removal of pure water was promoted by blowing N ₂ gas onto the wafer surface instead of supplying the IPA liquid. The results are shown in FIGS. 6B and 6C, respectively. 6 (b) and 6 (c), the number of watermarks is smaller when N ₂ gas is blown (FIG. 6 (c)) than when it is not blown (FIG. 6 (b)). There are many watermarks. On the other hand, according to the method of the embodiment, since the watermark is not visually recognized, it is understood that the method of the embodiment is very effective.

Then, in order to confirm the relationship between the conditions in the replacement and removal of pure water with the IPA liquid and the generation of the watermark, the distance (height (cm)) between the ejection portion of the replacement medium nozzle 8 and the surface of the wafer W is confirmed. ) And the inner diameter of the nozzle 8 (mm)
The results shown in FIG. 7 were obtained when the IPA liquid supply and the spin drying were performed by changing the IPA liquid supply rate (cm / sec) and the spin drying drying condition. At this time, the IPA liquid is supplied by positioning the discharge portion of the replacement medium nozzle 8 near the central portion of the wafer W and moving the wafer W to 80 r.
It was performed while rotating at pm. In addition, spin drying is
After the supply of the PA liquid, the wafer W is rotated at the first rotation speed of 300r.
Rotate for 1 second at pm, then the second rotation speed 3000r
It was performed by rotating at pm for 19 seconds (drying condition 1).

In FIG. 7, the number of generated watermarks is shown by a watermark average value (WM average value), and the evaluation is shown by a symbol. The watermark average value is the sum of the number of watermarks existing in each area of the watermark distribution (WM distribution) as shown in FIG. 8 and divided by the number of areas. ◎ indicates that the watermark is 0 and ◯ are 2.5 or less, Δ is 5 or less, and x is 5 or more.

It can be seen from FIG. 7 that when the inner diameter of the nozzle 8 is 4 mm, the average watermark value is lower than when it is 3 mm, so it is advisable to set the inner diameter of the nozzle 8 to 4 mm or more. It was Further, as the height of the nozzle 8 is lowered to 4.0 cm, 2.0 cm, and 1.0 cm, the average watermark value is also lowered to 2.0 c.
In the case of m, since the average watermark value when the inner diameter of the nozzle 8 is the same is considerably lower than that in the case of 4.0 cm, it is desirable to set the height of the nozzle 8 to 2.0 cm or less. Was recognized.

Particularly, when the height of the nozzle 8 is 2 cm or less, the inner diameter is 4 mm, and the supply flow rate is 117 cm / sec, the watermark average value is 1.3, and the other conditions are the same and the supply flow rate is the same. Of 78 cm / sec, the watermark average value was 0. Therefore, the height of the nozzle 8 was 2.0 cm or less, the inner diameter was 4 mm or more, and the supply flow velocity was 80.
It was confirmed that it is desirable to set it to be cm / sec or less.

In this way, the height of the nozzle 8 is 2.0 cm.
The reason why the generation of watermarks is suppressed when the inner diameter is 4 mm is supposed to be as follows.
The IPA liquid is supplied before the IPA liquid and is supplied on the pure water existing on the wafer W (see FIG. 9A). However, since the pure water and the IPA liquid have different surface tensions, It is considered that when the IPA liquid is supplied onto pure water, a phenomenon called Marangoni effect occurs.

The Marangoni effect is a phenomenon in which the liquid having a small surface tension is attracted to the liquid having a large surface tension. In the present embodiment, when the IPA liquid is supplied on pure water, For example, as shown in FIG. 9B, the IPA liquid having a small surface tension is attracted to the pure water having a large surface tension. Then, as shown in FIG. 9C, as the IPA liquid flows concentrically on the wafer W, the attracted portion also spreads concentrically. When the IPA liquid is attracted in this manner, the IPA liquid can also come into contact with the pure water that has entered the gaps between the patterns of the wafer W and the watermark components that have already been formed, so that the IPA liquid is easily dissolved in these pure water. It is presumed that

When the height of the nozzle 8 is as low as 2.0 cm or less and the inner diameter is as large as 4 mm or more, when the IPA liquid is supplied near the center of the wafer W, the IPA liquid easily spreads while concentrically spreading. Therefore, the above-mentioned Marangoni-
It is presumed that the effect is increased and that the occurrence of watermarks is suppressed. If the height of the nozzle 8 is high,
When the inner diameter is small, the IPA liquid is difficult to spread concentrically and uniformly, so that the force of attracting the IPA liquid to pure water becomes weak. Therefore, the IPA liquid and pure water may flow in a mixed state, or the IPA liquid may flow on the pure water so that the Marangoni effect may be reduced.

The effect of reducing the height of the nozzle 8 is not clear, but one reason is that the nozzle 8 is
Since the distance that the IPA liquid comes into contact with the atmosphere from the discharge port to the upper surface of the wafer W becomes shorter, the time during which the IPA liquid comes into contact with oxygen and moisture in the atmosphere is shorter than when the height of the nozzle 8 is high. It is conceivable that the amount of oxygen and water contained in the IPA liquid will decrease, and the amount of oxygen and water that will cause the watermark will decrease.

Next, in order to confirm the relationship between the drying conditions of spin drying and the generation of watermarks, the replacement medium nozzle 8
The height of the wafer was 1.0 cm, the inner diameter of the nozzle 8 was 4 mm, the supply flow rate was 44 cm / sec, the IPA solution was supplied while the wafer W was rotated at 80 rpm, and then spin drying was performed under different drying conditions. The results shown in FIG. 10 were obtained.

At this time, the drying condition 1 is the above-mentioned condition, and the drying condition 2 is that after the IPA liquid is supplied, the wafer W is rotated at 300 rpm which is the first rotation speed for 1 second, and then 3000 rp.
In the case of rotating at m for 4 seconds and finally at 5000 rpm for 15 seconds (here, 3000 rpm and 5000 rpm are the second rotation speeds), the drying condition 3 is that the wafer W after supplying the IPA liquid is the first rotation speed of 300 rpm. Spin for 1 second, then 2000 rpm for 4 seconds, and finally 400
When rotating at 0 rpm for 15 seconds (here, 2000r
pm and 4000 rpm as the second rotation number),
The drying condition 4 is that after the IPA liquid is supplied, the wafer W is rotated at a first rotation speed of 300 rpm for 1 second, and then 1000 r
It was set as the case of rotating at pm for 4 seconds and finally at 3000 rpm for 15 seconds (here, 1000 rpm and 3000 rpm are the second rotation speeds).

As shown in FIG. 10, when spin drying was performed under the above drying conditions, the second rotation speed was 2000.
It was confirmed that no watermark was observed at rpm or more. As a result, it is possible to suppress the generation of watermarks by rotating the wafer W at the first rotation speed after supplying the IPA liquid and then rotating the wafer W at the second rotation speed higher than the first rotation speed to perform spin drying. Is effective,
In particular, it was found that the second rotation speed is preferably 2000 rpm or more.

As described above, when the number of rotations of the wafer W is increased during spin drying, the generation of watermarks is suppressed because small particles of the IPA liquid are easily ejected.
Since the removal of the IPA liquid by the centrifugal force is promoted and the drying time is shortened, the reaction of forming a watermark due to a small amount of water in the IPA liquid is unlikely to occur, and the IPA liquid on the surface of the wafer W and the water in the atmosphere are not separated. It is presumed that this is because the contact time is reduced and the uptake of water in the atmosphere into the IPA liquid is suppressed.

If the number of revolutions is too high in the initial stage of the IPA solution removing step after the IPA solution is supplied, large particles of the IPA solution are splashed and the scattered IPA is returned by the impact force. The phenomenon that particle adhesion increases was observed. For this reason, first, large particles of the IPA liquid are blown off at the first rotation speed, and then at the second rotation speed.
It is desirable to increase the number of revolutions of (1) to repel small particles of the IPA liquid.

Further, rotating the wafer W at a high speed by the second rotation speed in this manner means that the mechanical chuck of the wafer W makes the wafer W contact with the clamp finger 38a.
It is also effective for drying the portion, so that it is possible to prevent the formation of the watermark in this portion. At this time, when the wafer W rotates at high speed, the clamp finger 38a holding the wafer W may be switched to the clamp finger 38b.

Then, in order to confirm the relationship between the rinse time by the IPA liquid and the generation of the watermark, the height of the replacement medium nozzle 8 is 1.0 cm, the inner diameter of the nozzle 8 is 4 mm,
Wafer W 80r with supply flow rate 44cm / sec
When the IPA liquid was supplied while changing the supply time while rotating at pm, spin drying was performed under drying condition 1, and the results shown in FIG. 11 were obtained.

According to this figure, the rinse time of the IPA solution is 3
It is recognized that the watermark does not occur if it is 2 seconds or less, but it does occur if it is 2 seconds or less. If the height of the nozzle 8 is 1.0 cm and the inner diameter is 4 mm or more, the rinse time is It was confirmed that 3 seconds or more is preferable. The reason for this is that if the rinse time is too short, I
It is presumed that this is because the PA liquid did not spread concentrically and could not sufficiently replace the pure water with the IPA liquid due to the Marangoni effect.

Next, a second embodiment of the present invention will be described. In this embodiment, for example, as shown in FIG.
The replacement medium nozzle 8 of the first embodiment is replaced by the replacement medium supply pipe 85. For example, in this embodiment, when the IPA is supplied, the wafer W is, for example, 30 rpm.
While rotating at 1, the IPA vapor is supplied from the substitution medium supply pipe 85 at a flow rate of, for example, 1000 ml / min for 10 seconds. At this time, for example, as shown in FIGS. 12A and 12B, the organic solvent supply pipe 85 is scanned in the radial direction from the center of the wafer W toward the outside, for example, to supply the IPA vapor.

Then, as in the first embodiment, after a predetermined drying condition, for example, the supply of the IPA vapor is stopped, the first rotation speed is 300 rpm and the rotation speed is 1 second for 30 seconds.
Rotate at 00 rpm for 4 seconds and then at 5000 rpm for 5 seconds (3000 rpm and 5000 rpm are the second
Of the processing chamber 30. For example, when the number of rotations is switched to the second number of rotations, spin drying is performed.
The inside is depressurized to a predetermined pressure, for example, the vapor pressure of the replacement medium at the temperature of the wafer W (60 mmHg at 30 ° C. in IPA).

Here, the IPA vapor must satisfy the temperature condition of room temperature ≦ pure water temperature ≦ IPA vapor temperature when the IPA vapor is supplied in relation to the temperature of the pure water supplied onto the wafer W before the IPA vapor. Is desirable. For example, room temperature is 25 ℃
If so, pure water is adjusted to about 30 ° C. and IPA vapor is adjusted to 80 ° C., respectively. As such IPA vapor, I
In addition to IPA vapor having a temperature around the boiling point of IPA obtained by heating the PA liquid and saturating it, a mixed gas having a temperature lower than the boiling point of IPA obtained by diluting such IPA vapor with N ₂ gas or the like can be used. it can.

When the IPA vapor is supplied onto the wafer W in this manner, the IPA vapor is cooled by coming into contact with the surface of the wafer W and the surface of the pure water when the temperature of the surface of the wafer W and the surface of the pure water is sufficiently low and saturated. Excess amount of IPA vapor condenses. When the temperature of the surface of the wafer W and the surface of pure water is sufficiently high, for example, when the temperature is equal to or higher than the boiling point of IPA, it is adsorbed on the surface of the wafer W and the surface of pure water. The temperature of the surface of the wafer W is IPA
It is substantially determined by the temperature of the pure water supplied before supplying the vapor. By setting the temperature condition in this way, it is possible to control the condensation and adsorption of the IPA vapor on the surface of the wafer W. .

In any of the above cases, when the temperatures of the IPA vapor and the pure water are set to the above-mentioned conditions, the IPA vapor is condensed on the wafer W by the pure water on the wafer W and is outward in a liquid state. Extruded, causing Marangoni effect. As a result, the pure water is replaced with the IPA vapor and removed from the surface of the wafer W. If the temperature of the pure water is too low, the IPA may remain in the liquid state in the center of the wafer W. Therefore, the temperature of the pure water is preferably set higher than room temperature.

Further, during spin drying, if the pressure in the processing chamber 30 is reduced to about the vapor pressure of IPA, the evaporation rate of IPA is increased, and the substitution is performed by the Marangoni effect.
Since the evaporation of PA is promoted, IPA can be removed in a short time. However, when reducing the pressure, it is desirable to reduce the exhaust speed in the initial stage. This is because if the exhaust speed is increased from the initial stage, large particles of IPA will be ejected and the impacted force will cause the scattered IPA to return and the particles will adhere.

Since the IPA vapor is obtained by vaporizing the IPA liquid, the vaporization removes the particles, high-boiling point components, metals and other impurities contained in the IPA liquid, which is higher than that of the IPA liquid. And the purity becomes higher. Therefore, as compared with the case where the IPA liquid is supplied, the amount of water and impurities brought into the surface of the wafer W by the IPA is reduced, so that the generation of the watermark can be further suppressed. Also IP
Since the vapor A is supplied while scanning the substitution medium supply pipe 86, it spreads evenly over the entire upper surface of the wafer W, and the pure water existing on the surface of the wafer W can be sufficiently removed.

In the above, in order to suppress the generation of the watermark in the mechanical chuck holding portion 34,
It is desirable to switch the clamp finger 38a holding the wafer W to the clamp finger 38b when switching the rotation speed to the second rotation speed during spin drying or when rotating at the second rotation speed. Further, at the time of spin drying, the exhaust gas amount may be increased as the rotation speed is increased, or at the time of spin drying, an inert gas such as N ₂ gas may be blown onto the surface of the wafer W.

Further, in the present embodiment, as shown in FIG. 13, for example, the rotary shaft 81 of the replacement medium supply pipe 85 and the rotary shaft 71 of the pure water nozzle 7 are arranged on both the left and right sides of the wafer W to form a pure water. The water nozzle 7 and the replacement medium supply pipe 85 are positioned above the wafer W so that the pure water nozzle 7 is on the outside.
These are scanned, for example, from the center of the wafer W toward the outside so that the pure water nozzle 7 precedes, and the pure water supply and I
The PA vapor may be supplied at the same time. By doing so, the pure water supplied to the surface of the wafer W is
It is immediately removed by the IPA vapor supplied at the same time, and the generation of watermarks can be effectively suppressed.

Further, in the present embodiment, as shown in FIG. 14, for example, the wafer W is attached to the tip of the replacement medium supply pipe 85.
A disk-shaped straightening plate 86 having a diameter substantially the same as
And may be provided so as to face each other with an interval of about 5 mm. In this embodiment, the IPA vapor is supplied without scanning the replacement medium supply pipe 85, and the supplied IP is supplied.
Since the A vapor flows along the straightening vanes 86 and diffuses in the space between the straightening vanes 86 and the wafer W, the IPA vapor becomes easy to reach the peripheral portion of the wafer W. When the wafer W is rotated during the supply of the IPA vapor, the IPA vapor spreads more evenly on the wafer W.

In the present embodiment, the replacement medium supply pipe 85 may be scanned to supply the IPA vapor without rotating the wafer W. Further, after the IPA vapor is supplied, the number of rotations increases to the second number of rotations during spin drying,
It is possible to perform only one of them without performing both decompression in the processing chamber, and it is confirmed that IPA is removed without remaining on the wafer W even if only one of them is performed in this way. Has been done.

In the above, the present invention is applied not only to the hydrofluoric acid processing section but also to the APM processing section and HPM processing section. In the present invention, an LCD substrate may be used as the substrate to be processed, and the chemical liquid may be other than hydrofluoric acid,
Furthermore, the same effect can be obtained by using a volatile surfactant instead of the substitution medium.

[0062]

As described above, according to the present invention, since the cleaning liquid can be promptly removed from the substrate to be processed, it is possible to suppress the generation of deposits caused by the cleaning liquid and reduce the generation of particles. it can.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a cleaning station including a cleaning device according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional side view showing a main part of the cleaning device according to the first embodiment of the present invention.

FIG. 3 is a plan view showing a main part of the cleaning device according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing each nozzle and a control unit.

FIG. 5 is a process drawing showing the first embodiment of the method of the present invention.

FIG. 6 is an explanatory diagram showing the results of cleaning evaluation for Examples and Comparative Examples.

FIG. 7 is an explanatory diagram showing results of evaluation of cleaning when IPA supply conditions are changed.

FIG. 8 is an explanatory diagram showing a watermark distribution.

FIG. 9 is an explanatory diagram for explaining the Marangoni effect.

FIG. 10 is an explanatory diagram showing the results of evaluation of cleaning when the drying conditions for spin drying are changed.

FIG. 11 is an explanatory diagram showing results of evaluation of cleaning when the IPA rinse time is changed.

FIG. 12 is an explanatory diagram showing the operation of the second embodiment of the present invention.

FIG. 13 is an explanatory diagram showing an operation of another example of the second exemplary embodiment of the present invention.

FIG. 14 is an explanatory diagram showing an operation of still another example of the second exemplary embodiment of the present invention.

FIG. 15 is a process diagram showing a conventional cleaning method.

FIG. 16 is an explanatory diagram showing an example of the surface structure of a wafer to be cleaned.

[Explanation of symbols]

3 Rotating mount 31 rotation mechanism 4 inner cup 41 Receptacle 5 outside cups 51 mouth 6 chemical nozzle 60 hydrofluoric acid solution 7 Pure water nozzle 70 Pure water 8 Replacement medium nozzle 80 Isopropyl alcohol 85 Replacement medium supply pipe 86 straightening plate

Claims (18)

(57) [Claims] 1. A step of supplying a cleaning liquid to the surface of the substrate to be cleaned while mounting and rotating the substrate to be processed on a rotary mounting part , and a cleaning liquid while rotating the substrate to be processed subsequently. Supply
A step of supplying a replacement medium liquid to the surface of the substrate to be processed from the middle of the process of replacing the cleaning liquid with the replacement medium liquid, and then rotating the substrate to be processed to replace the replacement medium liquid on the surface of the substrate to be processed. A step of removing by centrifugal force by rotation,
The cleaning method, wherein the replacement medium liquid is miscible with the cleaning liquid and has a smaller surface tension than the cleaning liquid. 2. A step of placing a substrate to be processed on a rotary mounting portion and rotating the substrate while supplying a cleaning liquid to the surface of the substrate to be cleaned, and subsequently rotating the substrate to be processed. Supplying the replacement medium liquid to the surface of the substrate at a rate of 80 cm / sec or less to replace the cleaning liquid with the replacement medium liquid, and then rotating the replacement medium liquid on the surface of the substrate to be processed while rotating the substrate to be processed. The step of removing by centrifugal force by
The cleaning method, wherein the replacement medium liquid is miscible with the cleaning liquid and has a smaller surface tension than the cleaning liquid. 3. A step of placing a substrate to be processed on a rotary mounting part and rotating the substrate while supplying a cleaning liquid to the surface of the substrate to be cleaned, and subsequently, replacing medium vapor on the surface of the substrate to be processed. To be processed
Whether the supply position of the substitution medium vapor on the substrate is the center of the surface
From outside to supply while being scanned, and the cleaning liquid is replaced with the replacement medium liquid in which the replacement medium vapor is condensed, and then the replacement medium liquid on the surface of the substrate to be processed is rotated while rotating the substrate to be processed. The step of removing by centrifugal force by
The method of cleaning according to claim 1, wherein the displacement medium vapor is miscible with the cleaning liquid and has a surface tension smaller than that of the cleaning liquid. 4. The cleaning method according to claim 3, wherein the step of supplying the substitution medium vapor to the surface of the target substrate is performed while rotating the target substrate. 5. Prior to the step of supplying a cleaning liquid to the surface of the substrate to be processed and cleaning the substrate, the chemical liquid is supplied to the surface of the substrate to be processed while the substrate to be processed is placed on the rotary mounting part and rotated. The cleaning method according to any one of claims 1 to 4, further comprising a step of treating with a chemical solution. While 6. times is rotated by placing a substrate to be processed reproduction part, the object to be from the middle that supplies the washing by supplying a cleaning liquid to the surface of the substrate, followed by washing solution Supplying the substitution medium vapor to the surface of the processing substrate, and replacing the cleaning liquid with the substitution medium liquid dew condensation of the substitution medium vapor, and then the substitution medium liquid on the surface of the substrate to be treated while rotating the substrate to be treated. A step of removing by centrifugal force by rotation,
The method of cleaning according to claim 1, wherein the displacement medium vapor is miscible with the cleaning liquid and has a surface tension smaller than that of the cleaning liquid. 7. A step of supplying a cleaning liquid to the surface of the substrate to be cleaned while mounting and rotating the substrate to be processed on the rotary mounting part, and subsequently, a substitution medium vapor on the surface of the substrate to be processed. Supply
A step of substituting the cleaning liquid with a substitution medium liquid in which the substitution medium vapor is condensed, and a step of removing the substitution medium liquid on the surface of the substrate to be processed by rotation while rotating the substrate to be processed, by a centrifugal force.
Hints, the replacement medium vapor, there are mixed with the cleaning liquid and before the surface tension small KuKatsu substituted vapor medium from the cleaning solution
A cleaning method, wherein the temperature is equal to or higher than the temperature of the supplied cleaning liquid . 8. A substrate to be processed is placed on a rotary placement part and rotated.
While cleaning, supply the cleaning liquid to the surface of the substrate to be processed
And the process of Subsequently, while rotating the substrate to be processed, the surface of the substrate to be processed is displayed.
Supply the replacement medium liquid to the surface and apply the cleaning liquid to the replacement medium liquid.
Replacing with After that, the surface of the substrate to be processed is rotated while rotating the substrate to be processed.
A step of removing the replacement medium liquid on the surface by centrifugal force due to rotation,
Including,The step of removing the replacement medium liquid on the surface of the substrate to be processed is the first step.
Substrate to be processed at The first rotation speed
While rotating the substrate to be processed at a second rotation speed higher than
Done, The displacement medium liquid is miscible with the cleaning liquid and
Cleaning method characterized by having a lower surface tension than the cleaning liquid
Law. 9. A substrate to be processed is placed on a rotary mounting part and rotated.
While cleaning, supply the cleaning liquid to the surface of the substrate to be processed
And the process of Subsequently, a substitution medium vapor is supplied to the surface of the substrate to be processed,
The cleaning liquid is replaced with the replacement medium liquid in which the replacement medium vapor is condensed.
The step of replacing, After that, the surface of the substrate to be processed is rotated while rotating the substrate to be processed.
A step of removing the replacement medium liquid on the surface by centrifugal force due to rotation,
Including,The step of removing the replacement medium liquid on the surface of the substrate to be processed is the first step.
The substrate to be processed is rotated at a rotation speed of
While rotating the substrate to be processed at a second rotation speed higher than
Done, The displacement medium vapor is miscible with the cleaning liquid and
Cleaning method characterized by having a lower surface tension than the cleaning solution
Law. 10. The cleaning method according to claim 8, wherein the second rotation speed is 2000 rpm or more. 11. The step of removing the substitution medium liquid on the surface of the substrate to be processed is performed under reduced pressure.
11. The cleaning method according to any one of 1 to 10 . 12. An apparatus for supplying a cleaning liquid to a surface of a substrate to be cleaned while mounting and rotating the substrate to be processed on a rotary mounting part, for supplying the cleaning liquid to the surface of the substrate to be processed. A cleaning liquid supply unit, a replacement medium fluid supply unit for supplying a replacement medium fluid that is miscible with the cleaning liquid and has a smaller surface tension than the cleaning liquid to the surface of the substrate to be processed, and a cleaning liquid for the surface of the substrate to be processed. And a control unit for switching the supply of the replacement medium fluid to the supply of the replacement medium fluid. 13. The cleaning apparatus according to claim 12 , wherein the rotary mounting portion includes a clamp portion that engages with a side portion of the substrate to be processed and holds the substrate. 14. The rotary mounting part includes a first clamp part and a second clamp part for engaging with a side part of the plate to be processed and holding the substrate. When the replacement medium fluid is supplied, the substrate to be processed is held by the first clamp portion, and after the replacement medium fluid is supplied, the second substrate is held.
13. The cleaning apparatus according to claim 12, wherein the substrate to be processed is held by the clamp part. 15. The replacement medium fluid supply unit is for supplying a replacement medium liquid, the discharge unit faces the central portion of the substrate to be processed, and the discharge unit is a nozzle having a diameter of 4 mm or more. The cleaning device according to any one of claims 12 to 14 , characterized in that. 16. The replacement medium fluid supply unit is for supplying the replacement medium liquid, and when the discharge unit faces the center of the substrate to be processed and supplies the replacement medium liquid to the surface of the substrate to be processed. claim distance between the discharge portion and the surface of the substrate to be processed substituted medium fluid supply unit is characterized by at 2cm or less 12
The cleaning device according to any one of 1 to 15 . 17. The replacement medium fluid supply unit supplies the replacement medium liquid or the replacement medium vapor, and the control unit supplies the cleaning liquid without interruption or after supplying the cleaning liquid to the surface of the substrate to be processed. 15. The cleaning apparatus according to claim 12 , wherein the supply is switched so that the replacement medium liquid is supplied to the surface of the substrate to be processed during the process. 18. The replacement medium fluid supply unit supplies the replacement medium vapor, and the supply position of the replacement medium vapor of the substrate to be processed is scanned outward from the center of the surface. 18. The cleaning device according to claim 12 or 17 .