JP2003086491A - Treatment method of substrate, and forming method of coating film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a treatment method of a substrate and a forming method of a coating film for forming the coating film with small number of defects. SOLUTION: A forming process of a resist film on a semiconductor wafer includes first step of coating a resist solution on the wafer, a second step of spreading the resist solution over the entire wafer and adjusting the film thickness to a prescribed level, and a third step of treating the wafer with the resist film by heat at a prescribed temperature. In the third step, the heat treatment temperature, heat treatment time or heat-up pattern is set according to the quantity of solvent contained in the resist solution, so that the number of defects generated in the resist film can be reduced. As an example, instead of a baking method (STD), in which baking is carried out, from the beginning at the target temperature, a step baking method, in which the baking is carried out at the target temperature after the baking at a temperature lower than the target temperature, is employed so that the number of defects can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate processing method which is performed prior to forming a resist film, a protective film, an insulating film or the like on a substrate such as a semiconductor wafer, and for forming these various films. The present invention relates to a coating film forming method.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, a so-called photolithography technique is used to form a predetermined circuit pattern on the surface of a semiconductor wafer.
In this photolithography process, for example, a series of processes is performed in which a photoresist solution is applied to a cleaned semiconductor wafer to form a resist film, the resist film is exposed in a predetermined pattern, and this is developed. ing.

As a method of forming a resist film, for example,
A semiconductor wafer is fixed to a spin chuck, then a predetermined amount of photoresist liquid is applied to the surface of the wafer and the spin chuck is rotated to spread the resist liquid over the entire wafer to adjust the film thickness to a predetermined value. A method of performing a predetermined heat treatment (baking treatment) can be mentioned. The thickness of the resist film thus formed is generally 300 nm to 60 nm.
It is about 0 nm.

[0004]

However, in recent years,
As semiconductor devices become highly integrated and miniaturized, for example, it is possible to form a circuit pattern having a line width narrower than before by using light of a short wavelength such as KrF line, ArF line, and F ₂ line as an exposure light source. Is coming. In this case, the resist film is generally formed thinner than the conventional one so that the film thickness is, for example, 150 nm or less. However, if the resist film is so thin, many defects occur in the resist film. There is a problem formed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a substrate processing method and a coating film forming method capable of forming a coating film with a small number of defects.

[0006]

According to a first aspect of the present invention, there is provided a substrate processing method which is applied to a surface of a substrate on which a coating film is formed, which is prior to the formation of the coating film. ,
There is provided a substrate processing method, which comprises irradiating the surface of the substrate with ultraviolet rays having a wavelength of 180 nm to 250 nm for 30 seconds to 50 seconds to reduce the number of defects on the surface of the substrate.

According to a second aspect of the present invention, there is provided a substrate processing method which is performed on a surface of a substrate on which a coating film is formed before forming the coating film, the method being prior to forming the coating film. A first step of reducing the defects on the surface of the substrate by bringing the surface of the substrate into contact with an organic solvent and holding the same for a predetermined time;
A substrate processing method comprising: a second step of removing the organic solvent from the surface of the substrate; and a third step of rinsing the substrate.

According to a third aspect of the present invention, there is provided a substrate processing method which is carried out on a surface of a substrate on which a coating film is formed, wherein the substrate is subjected to 400 times prior to the formation of the coating film.
There is provided a substrate processing method, characterized in that the number of defects on the surface of the substrate is reduced by holding the substrate in an inert gas atmosphere for 30 seconds to 120 seconds in a temperature range of ℃ to 800 ℃.

As a result of studying the reason why many defects occur in the coating film when the thickness of the coating film becomes thinner than a certain level as described above, as a result, defects are present on the surface of the substrate and are formed thereon. It has been found that when the thickness of the coating film becomes thinner than a certain level, defects on the surface of the substrate are likely to be directly reflected as defects in the coating film. Conventionally, since the thickness of the coating film formed is large, even if there are minute defects on the surface of the substrate after the cleaning treatment, for example, even if there are deposits such as particles or polishing scratches, these defects The number of defects generated in the coating film is suppressed below a predetermined standard because the coating film can be ignored by being covered with the coating film or filled. However, when the thickness of the coating film becomes thinner than a certain level, such an effect becomes difficult to occur. Therefore, the inventions of the first to third aspects reduce the number of defects in the coating film formed on the surface of the substrate by paying attention to such a point and reducing the number of defects in the surface of the substrate. As a result, a high quality coating film can be obtained,
Product reliability can be increased.

According to a fourth aspect of the present invention, there is provided a coating film forming method for forming a coating film by coating a substrate with a coating liquid,
As the coating solution, the number of defects formed in the coating film is adjusted by using a coating solution in which the content of microbubbles is adjusted to a certain value or less, or the dissolved gas amount is adjusted to a certain value or less. A method for forming a coating film, which is characterized by reducing the amount.

According to a fifth aspect of the present invention, a first step of applying a coating liquid to a substrate and a second step of spreading the coating liquid over the entire substrate to adjust the film thickness of the coating film to a predetermined value. And a third step of heat-treating the substrate on which the coating film is formed at a predetermined temperature. In the third step, the heat treatment temperature, the heat treatment time, or the heat treatment temperature is increased according to the amount of the solvent contained in the coating liquid. Provided is a coating film forming method characterized by setting a temperature pattern.

As described above, in the process of studying the reason why many defects occur in the coating film when the thickness of the coating film is made thinner than a certain level, defects not based on defects on the surface of the substrate are also found. It has been confirmed that it has occurred. One of the reasons for this is that the coating liquid used for forming a thin coating film contains a large amount of solvent that evaporates in the subsequent heat treatment in order to reduce the viscosity. It is conceivable that the conventional process of forming a thick coating film is used as it is as the process of forming a thin coating film. For example, if the same condition as the conventional baking treatment of a thick coating film is used for the baking treatment of a thin coating film,
It is presumed that defects occur in the coating film due to bumping of the solvent contained in the coating liquid in a large amount. Further, a certain amount of gas such as nitrogen gas is dissolved in the coating liquid, but when the film thickness of the coating film becomes thin, the dissolved gas contained in the coating liquid spreads the coating liquid over the substrate or during the baking process. It is presumed that defects such as pinholes are generated. Therefore, the inventions of the fourth and fifth aspects pay attention to such a point and suppress the number of defects that occur when the coating film is formed. This makes it possible to obtain a high-quality coating film and improve the reliability of the product.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, as the substrate processing method and the coating film forming method, a wafer processing method and a resist film forming method when forming a resist film on a semiconductor wafer will be exemplified. FIG. 1 is a schematic plan view showing a resist coating / development processing system 1 for consistently performing resist coating on a semiconductor wafer to developing processing, FIG. 2 is a front view thereof, and FIG. 3 is a rear view thereof.

The resist coating / development processing system 1 includes a wafer between a cassette station 10 as a transfer station, a processing station 11 having a plurality of processing units, and an exposure device (not shown) provided adjacent to the processing station 11. And an interface unit 12 for delivering W.

The cassette station 10 is loaded with a plurality of wafers W as the objects to be processed, for example, in units of 25 wafers in the wafer cassette CR, and is carried into the resist coating / developing processing system 1 from another system. Alternatively, the wafer cassette CR and the processing station 11 may be carried out from the resist coating / developing processing system 1 to another system.
This is for carrying the wafer W between and.

In the cassette station 10, as shown in FIG. 1, a plurality of (four in the figure) positioning projections 20a are formed on the cassette mounting table 20 along the X direction in the figure. Wafer cassette C in position
The Rs can be placed in a line with their respective wafer entrances and exits facing the processing station 11 side. In the wafer cassette CR, the wafers W are arranged in the vertical direction (Z direction). Further, the cassette station 10 has a wafer transfer mechanism 21 located between the cassette mounting table 20 and the processing station 11.

The wafer transfer mechanism 21 has a wafer transfer arm 21a which is movable in the cassette arrangement direction (X direction) and the arrangement direction of the wafers W in the cassette (Z direction). This makes it possible to selectively access one of the wafer cassettes CR. Further, the wafer transfer arm 21a is configured to be rotatable in the θ direction shown in FIG. 1, and an alignment unit (ALIM) and an extension unit belonging to a _third processing unit G ₃ on the processing station 11 side described later. You can also access (EXT).

On the other hand, the processing station 11 uses the wafer W
A plurality of processing units for carrying out a series of steps for performing coating and development on the wafer are provided, and these are arranged in multiple stages at predetermined positions, and these process wafers W one by one. As shown in FIG. 1, the processing station 11 has a wafer transfer path 22a at the center thereof, a main wafer transfer mechanism 22 is provided therein, and all processing units are provided around the wafer transfer path 22a. It is arranged. The plurality of processing units are divided into a plurality of processing units, and each processing unit has a plurality of processing units arranged in multiple stages along the vertical direction (Z direction).

As shown in FIG. 3, the main wafer transfer mechanism 22 is equipped with a wafer transfer device 46 inside a cylindrical support 49 so as to be vertically movable (Z direction). The cylindrical support 49 can be rotated by the rotational driving force of a motor (not shown), and the wafer transfer device 46 can be integrally rotated accordingly. The wafer transfer device 46 includes a plurality of holding members 4 that are movable in the front-rear direction of the transfer base 47.
8, and the holding member 48 realizes the delivery of the wafer W between the processing units.

As shown in FIG. 1, in the resist coating / development processing system 1, five processing sections G ₁ , G ₂ and G are provided.
₃ · _G 4 · _{G 5} are actually arranged around the wafer transport path 22a. Of these, the first and second processing sections G ₁ and G ₂ are arranged in parallel on the front side (front side in FIG. 1) of the resist coating / developing processing system 1, and the third processing section G ₃ is a cassette. The fourth processing unit G ₄ is arranged adjacent to the station 10, and the fourth processing unit G ₄ is arranged adjacent to the interface unit 12. Further, the fifth processing unit G ₅ is arranged on the back surface portion.

In the first processing section G ₁ , the coater cup (C
In P), a resist coating unit (COT), which is two spinner type processing units for carrying out a predetermined process by placing a wafer W on a spin chuck (not shown), and a developing unit (DEV) for developing a resist pattern are arranged in order from the bottom. It is stacked in two layers. Similarly, the second processing section G ₂ is also a resist coating unit (C
OT) and a developing unit (DEV) are stacked in two stages in order from the bottom.

In the third processing section G ₃ , as shown in FIG. 3, a plurality of oven-type processing units for stacking the wafer W on the mounting table SP and performing predetermined processing are stacked.
That is, an adhesion unit (AD) that performs a so-called hydrophobic treatment for improving the fixability of the resist, an alignment unit (ALIM) that performs alignment, and an extension unit (EX that loads and unloads the wafer W).
T), a cooling unit (COL) that performs cooling processing,
Wafer W before and after exposure processing and after development processing
The four hot plate units (HP) that perform the heat treatment are stacked in eight stages in order from the bottom. A cooling unit (COL) is provided instead of the alignment unit (ALIM), and the cooling unit (CO
L) may have an alignment function.

Also in the fourth processing section G ₄ , oven-type processing units are stacked in multiple stages. That is, a cooling unit (COL), an extension / cooling unit (EXTCOL) that is a wafer loading / unloading unit equipped with a cooling plate, an extension unit (EXT), a cooling unit (COL), and four hot plate units (HP) are located below. In order from 8
It is stacked in columns.

The fifth processing section G ₅ can move laterally along the guide rail 25 as viewed from the main wafer transfer mechanism 22. Therefore, by sliding the fifth processing unit G ₅ along the guide rail 25, a space is secured, so that maintenance work can be easily performed on the main wafer transfer mechanism 22 from behind. In the resist coating / developing processing system 1, the fifth processing unit G
UV irradiation unit for performing ultraviolet irradiation treatment (UV) is against ₅ to the wafer W, for example, provided on the upper and lower stages.
1 to 3, the ultraviolet irradiation unit (U
V) is not shown. Further, the fifth processing unit G ₅ can be arranged as necessary and is not always required.

The interface section 12 has a depth direction (X
(Direction), it has the same length as the processing station 11. As shown in FIGS. 1 and 2, a portable pickup cassette CR and a stationary buffer cassette BR are arranged in two stages on the front surface of the interface unit 12, and a peripheral exposure device 23 is arranged on the rear surface. A wafer transfer mechanism 24 is provided at the center. The wafer transfer mechanism 24 has a wafer transfer arm 24a, and the wafer transfer arm 24a moves in the X and Z directions to move both cassettes CR and BR and the peripheral exposure apparatus 2.
3 is accessible.

The wafer transfer arm 24a is rotatable in the θ direction and is an extension unit (EXT) belonging to the fourth processing section G ₄ of the processing station 11.
Further, it is also possible to access a wafer transfer table (not shown) on the adjacent exposure apparatus side.

In the resist coating / developing system 1 described above, first, in the cassette station 10, the wafer transfer arm 21a of the wafer transfer mechanism 21 accommodates an unprocessed wafer W on the cassette mounting table 20. The cassette CR is accessed to take out one wafer W, and the wafer W is transferred to the extension unit (EXT) of the third processing unit G ₃ .

The wafer W is transferred from the extension unit (EXT) to the ultraviolet irradiation unit (UV) of the fifth processing section G ₅ by the wafer transfer device 46 of the main wafer transfer mechanism 22 as required, and there. Ultraviolet irradiation processing is performed. Next, the wafer W is transferred to the alignment unit (ALIM) of the third processing unit G ₃ to be aligned, and then transferred to the adhesion processing unit (AD), where a hydrophobic treatment for improving the fixability of the resist ( HMDS processing) is performed. Since this process involves heating, the wafer W is then transferred to the cooling unit (COL) by the wafer transfer device 46 and cooled.

Depending on the type of resist used, the wafer W may be directly transferred to the resist coating unit (COT) without the HMDS process.
For example, a case where a polyimide resist is used can be given.

The wafer W that has been processed by the adhesion processing unit (AD) and cooled by the cooling unit (COL), or the adhesion processing unit (A).
The wafer W that has not been processed in D) is subsequently transferred by the wafer transfer device 46 to the resist coating unit (COT) where the resist is applied and a coating film is formed. After the coating process is completed, the wafer W is pre-baked in the hot plate unit (HP) of either the third or fourth processing unit G ₃ · G ₄ and then cooled in any cooling unit (COL). To be done.

The cooled wafer W is transferred to the third processing unit G ₃
Is conveyed to the alignment unit (ALIM), where it is aligned, it is conveyed to the interface section 12 via the fourth processing unit G ₄ extension units (EXT).

The wafer W is subjected to peripheral exposure by the peripheral exposure device 23 in the interface section 12 to remove excess resist, and then transferred to an exposure apparatus (not shown) provided adjacent to the interface section 12, where a predetermined amount is provided. The resist film on the wafer W is exposed according to the pattern.

The exposed wafer W is returned to the interface section 12 again, and the wafer transfer mechanism 24 is used to extend the extension unit (EX) belonging to the fourth processing section G _4.
It is transported to T). Then, the wafer W is transferred to one of the hot plate units (H
The sheet is conveyed to P), subjected to post-exposure bake processing, and then cooled by a cooling unit (COL).

Thereafter, the wafer W is transferred to the developing unit (DE
V), where the exposure pattern is developed. After the development is completed, the wafer W is transferred to one of the hot plate units (HP), subjected to the post-baking process, and then cooled by the cooling unit (COL). After completion of such a series of processing, the wafer is returned to the cassette station 10 via the extension unit (EXT) of the third processing unit G ₃ and is accommodated in any of the wafer cassettes CR.

Next, the resist coating unit (C
OT) will be described. 4 and 5 are a schematic cross-sectional view and a schematic plan view showing the overall configuration of the resist coating unit (COT). Resist coating unit (CO
An annular coater cup (CP) is arranged at the center of T), and the spin chuck 5 is provided inside the coater cup (CP).
2 are arranged. The spin chuck 52 is rotationally driven by a drive motor 54 while holding the wafer W fixed by vacuum suction. A drain 69 is provided at the bottom of the coater cup (CP), and an unnecessary processing liquid such as a resist liquid shaken off from the wafer W is discharged from here.

The drive motor 54 is arranged so as to be movable up and down in an opening 50a provided in the unit bottom plate 50, and via a cap-shaped flange member 58 made of, for example, aluminum, a raising / lowering drive means 60 made of, for example, an air cylinder and a raising / lowering guide. It is connected to the means 62. A cylindrical cooling jacket 64 made of, for example, SUS is attached to the side surface of the drive motor 54, and the flange member 58 is attached so as to cover the upper half portion of the cooling jacket 64.

For example, when the resist liquid is applied to the wafer W, the lower end 58a of the flange member 58 has an opening 50a.
In the vicinity of the outer periphery of the unit, the unit bottom plate 50 is tightly adhered, and the inside of the unit is sealed thereby. When the wafer W is transferred between the spin chuck 52 and the holding member 48 of the main wafer transfer mechanism 22, the lift drive means 60 lifts the drive motor 54 or the spin chuck 52 upward to lower the lower end of the flange member 58. Are floated from the unit bottom plate 50.

The resist nozzle 86 for ejecting the resist liquid onto the wafer W is detachably attached to the front end of the resist nozzle scan arm 92 via the nozzle holder 100, and the resist nozzle 86 receives the resist from the resist liquid supply unit 95. Liquid is supplied. The resist nozzle scan arm 92 is attached to a vertical support member 96 which is horizontally movable on a guide rail 94 laid in one direction (Y direction) on the unit bottom plate 50,
The Y-axis drive mechanism 111 moves in the Y direction integrally with the vertical support member 96. The registration nozzle 86 is moved in the vertical direction (Z
Direction).

The resist nozzle scan arm 92
Can be moved in the X direction at right angles to the Y direction in order to selectively attach the resist nozzle 86 in the resist nozzle waiting section 90, and can also be moved in the X direction by an X direction drive mechanism (not shown). . In the resist nozzle standby unit 90, the discharge port of the resist nozzle 86 is inserted into the port 90a of the solvent atmosphere chamber and exposed to the solvent atmosphere therein, so that the resist liquid at the nozzle tip is not solidified or deteriorated. .

The resist nozzle standby unit 90 is provided with a plurality of resist nozzles 86, and these nozzles can be selectively used according to the type of resist liquid, for example. Correspondingly, a plurality of resist liquids can be supplied from the resist liquid supply unit 95 to the resist nozzle 86.

On the nozzle holder 100 at the tip of the resist nozzle scan arm 92, a thinner nozzle 1 for ejecting a solvent for wetting the wafer surface, for example, a thinner, prior to the ejection of the resist liquid onto the wafer surface.
01 is attached. This thinner nozzle 101
Is connected to the thinner supply unit via a solvent supply pipe (not shown). The position when the thinner is ejected from the thinner nozzle 101 onto the wafer W is adjusted by the Y-axis drive mechanism 111 and an X-axis drive mechanism (not shown).

On the guide rail 94, not only the vertical support member 96 that supports the resist nozzle scan arm 92 but also the rinse nozzle scan arm 120 is supported, and Y
A vertical support member 124, which is movable in the direction, is also provided. A rinse nozzle 122 for side rinse is attached to the tip of the rinse nozzle scan arm 120. The rinse nozzle scan arm 120 and the rinse nozzle 122 are provided with standby positions outside the coater cup (CP) shown in FIG.
It is movable in the Y direction so as to be located in the peripheral portion of the. As the rinse liquid (cleaning liquid), a solvent (volatile solvent) contained in the resist liquid is preferably used.

The resist coating unit (COT) is provided with a rotatable pivot member 131. The pivot member 131 has a cleaning nozzle 133 having a cleaning nozzle 133 for applying a predetermined cleaning liquid to the wafer W at the tip thereof. Arm 132
Is attached. The cleaning nozzle arm 132 and the cleaning nozzle 133 are provided with standby positions outside the coater cup (CP) shown in FIG. 5 so as not to collide with the rinse nozzle scan arm 120 and the rinse nozzle 122.
The cleaning nozzle 133 can be rotated so as to be located at the center of the wafer W held by the spin chuck 52. As described above, the resist coating unit (COT) can perform the surface treatment of the wafer W by applying a predetermined cleaning liquid to the wafer W before forming the resist film in addition to forming the resist film. Has become.

An air supply member 70 is provided in the upper part of the resist coating unit (COT), and an auxiliary filter 71 is attached to the lower part of the air supply member 70. A predetermined gas such as air whose temperature and humidity are adjusted is supplied to the air supply member 70 from the blower unit 130, and the air thus supplied passes through the auxiliary filter 71 and is blown into the resist coating unit (COT). The temperature and humidity inside the coater cup (CP) are kept constant.

A main filter 72 for collecting particles is provided between the blower unit 130 and the air supply member 70, and particles such as dust contained in the air blown by the main filter 72 are collected. Then, air or the like having a small particle content is supplied to the resist coating unit (COT). In this way, particles and the like are prevented from adhering to the wafer W, and an increase in the number of defects on the wafer W can be suppressed.

The auxiliary filter 71 also collects particles such as dust contained in the blown air. Main filter 72
Since particles and the like may be generated in the middle of the pipe between the air supply member 70 and the air supply member 70, the reliability is further improved by providing the auxiliary filter 71 to collect the particles and the like. ULPA filters are preferably used as the auxiliary filter 71 and the main filter 72.

Such a resist coating unit (CO
In T), prior to the start of processing, the blower unit 1
Air is blown from 30 to the resist coating unit (COT), and the temperature and humidity inside the resist coating unit (COT) are kept constant. The air blow from the air blow unit 130 is continuously performed while the resist coating process is performed.

With the atmosphere in the resist coating unit (COT) being adjusted, the resist coating unit (COT) is held by the holding member 48 of the main wafer transfer mechanism 22.
The wafer W, which has been transferred to just above the coater cup (CP) in the inside thereof, is moved up and down by a lift drive means 6 composed of an air cylinder, for example.
It is vacuum-adsorbed by the spin chuck 52 that has been raised by 0 and the elevating guide means 62. The main wafer transfer mechanism 22 vacuum-sucks the wafer W onto the spin chuck 52, and then holds the holding member 48 on the resist coating unit (CO.
Pull back from inside T), resist coating unit (COT)
The transfer of the wafer W to the wafer is completed.

Next, in the spin chuck 52, the wafer W descends to a fixed position in the coater cup (CP), and the drive motor 54 starts the rotational driving of the spin chuck 52. After that, the movement of the nozzle holder 100 from the resist nozzle standby unit 90 is started. This nozzle holder 1
The movement of 00 is performed along the Y direction.

When the discharge port of the thinner nozzle 101 reaches the center of the spin chuck 52 (the center of the wafer W), the thinner is supplied to the surface of the rotating wafer W.
The thinner supplied to the surface of the wafer W is evenly spread from the center of the wafer W to the entire periphery thereof by the centrifugal force.
Thus, by performing the so-called pre-wet process of wetting the entire surface of the wafer W with a solvent such as thinner before applying the resist solution, the resist solution is more likely to diffuse, and as a result, a smaller amount of the resist solution is obtained. Thus, a uniform resist film can be formed.

Next, the nozzle holder 100 is moved in the Y direction until the discharge port of the resist nozzle 86 reaches the center of the wafer W, and the surface of the wafer W on which the resist solution is rotated from the discharge port of the resist nozzle 86. Dropped in the center,
The resist film is formed on the wafer W by being diffused from the center of the wafer W toward the periphery by the centrifugal force.

After the dropping of the resist solution, the wafer W is rotated at a predetermined rotation speed to adjust the film thickness. When the rotation speed of the wafer W is accelerated and becomes large, the remaining resist solution is shaken off and the drying progresses to form a resist film having a predetermined thickness. At this time, the resist coating unit (C
Since the temperature and humidity inside OT) are kept constant, the drying rate of the resist solution is stabilized, and the problem that the thickness of the resist film is different among W wafers is avoided.

After that, the resist nozzle 86 is turned on.
Move in the Y direction so that it can be accommodated in the slide waiting unit 90, and
Back rinse to the back surface of the wafer W by a cleaning means not shown.
Treated, and use rinse nozzle 122 if necessary
Then, the side edge portion of the wafer W is subjected to side rinse processing. That
Then, the cleaning solution was shaken off by performing a rotation process for a predetermined time.
After that, the rotation of the wafer W is stopped and the coating process is completed.
It The wafer W having the resist film formed thereon is again held by the holding member 4
8 and the third or fourth processing unit G_Three・ G _Fourof
Stored in either hot plate unit (HP)
Then, a pre-baking process is performed.

In order to obtain a high-quality resist film by using the above-described resist film forming method, the number of surface defects on the wafer W is reduced, and further, the defects generated in the resist film due to the characteristics of the resist solution are eliminated. It is necessary to reduce the number. Various treatments for this are performed by changing the thickness of the resist film to, for example, 15
It becomes clear from FIG. 6 and FIG. 7 described below that it becomes particularly important when the thickness is 0 nm or less.

FIG. 6 is a graph showing the relationship between the thickness of the resist film and the number of pinhole-like defects appearing on the surface of the resist film. FIG. 7 is a graph showing the number of defects of the wafer W before forming the resist film and the number of defects after forming the resist film having a film thickness of about 110 nm. These Figure 6
The number of defects shown in FIG. 7 and FIG. 7 are both measured by a wafer surface defect inspection device and an atomic force microscope (AFM).

In FIG. 6, a resist film having a film thickness of 300 nm or less is formed using a resist solution having a viscosity of 1.8 cp (centipoise), and a resist film having a film thickness of more than 300 nm uses a resist solution having a viscosity of 5 cp. Are formed. From FIG. 6, when the thickness of the resist film becomes about 150 nm or less,
It can be seen that the number of defects is rapidly increasing.

FIG. 7 shows the result of comparison of the coordinates on the wafer W in which a defect is detected by the AFM before and after the resist film is formed together with the number of detected defects. It can be seen from FIG. 7 that approximately 80% of the defect positions after the resist film is formed match the defect positions of the wafer W before the resist film is formed (“due to wafer defects in FIG. 7”). It is understood that "defects") are present, and the remaining 20% are defects newly generated in the process of forming the resist film ("new defects accompanying formation of resist film" in FIG. 7).

From the above results, in order to form a resist film having a small film thickness and a small number of defects, firstly, a defect on the surface of the wafer W before the resist film is formed, for example, the size is about. It is considered important to reduce the number of defects of 300 nm or less as much as possible, and secondly to suppress the generation of defects in the process of forming the resist film. Various methods for achieving this object will be described below.

One method of reducing the number of defects on the surface of the wafer W is to subject the wafer W to a predetermined ultraviolet irradiation process. Specifically, a wavelength of 180 nm to 250 n
By irradiating ultraviolet rays of m for 30 to 50 seconds, particles or the like adhering to the surface of the wafer W can be decomposed and removed, and the number of defects on the surface can be reduced, which eventually occurs in the resist film. The number of defects can be reduced.

Another method for reducing the number of defects on the surface of the wafer W is a method of subjecting the wafer W to a liquid treatment with a predetermined chemical liquid. Specifically, an organic solvent that dissolves and removes particles and the like adhering to the surface of the wafer W, for example, isopropyl alcohol (IPA) is used as the chemical liquid.

As the liquid processing method, for example, since the cleaning nozzle 133 is attached to the resist coating unit (COT), the surface of the wafer W held by the spin chuck 52 is washed with an organic solvent, for example, from the cleaning nozzle 133. , IPA is applied to form a paddle on the surface of the wafer W, and the paddle is held for a predetermined time. As a result, particles such as organic substances on the surface of the wafer W are dissolved by the IPA.

Next, the spin chuck 52 is rotated to remove the IPA on the wafer W, and the wafer W is dried. Further, a rinse liquid such as thinner is supplied from the thinner nozzle 101 to the surface of the wafer W, and the resist liquid is applied from the resist nozzle 86 while the surface of the wafer W is in a wet state, that is, a so-called pre-wet state. By applying the resist solution to the surface of the wafer W in a pre-wet state in this manner, the resist solution can be uniformly applied to the surface of the wafer W with a small amount of resist.

In the above method, IPA is used as the organic solvent.
However, it is preferable to use an organic solvent that most efficiently dissolves the organic substance depending on the type of the organic substance attached to the surface of the wafer W. If there is a possibility that the organic solvent and the rinse liquid may be mixed with each other in the waste liquid treatment section depending on the type of the organic solvent used to cause a problem such as ignition, the coater cup (CP) has a double structure. It is preferable that the drainage of the organic solvent and the drainage of the rinse liquid are not mixed.

Yet another method of reducing the number of defects on the surface of the wafer W is to subject the wafer W to a predetermined heat treatment. Specifically, the wafer W is set at 400 ° C. to 800 ° C.
Hold in an inert gas atmosphere for 30 to 120 seconds in a temperature range of ° C. As a result, it is possible to reduce the number of defects on the surface of the wafer W by burning and removing organic substances and the like on the surface of the wafer W that could not be removed by the conventional heat treatment. Such heat treatment can be performed using either a hot plate unit (HP) provided in the third processing unit G ₃ or the fourth processing unit G ₄ .

It is also possible to apply such heat treatment conditions to the adhesion treatment before resist coating. Further, the wafer W is processed by combining the method of reducing the number of defects by the ultraviolet irradiation treatment described above or the method of reducing the number of defects by the liquid treatment with the organic solvent described above with the method of reducing the number of defects by the heat treatment. Thus, defects having different properties can be reduced.

Next, a method for reducing the number of defects generated when forming the resist film will be described. One of the methods is a resist solution in which the amount of micro bubbles contained in the resist solution is adjusted to a certain value or less, or the amount of dissolved gas such as nitrogen gas dissolved in the resist solution is adjusted to a certain value or less. Is a method of coating the wafer W by using. If microscopic bubbles exist in the resist solution, the microscopic bubbles may cause pinhole defects at the time of adjusting the film thickness of the resist film, and if the dissolved gas amount is large, the subsequent heat treatment At times, volume expansion may occur, causing pinhole defects.

As a specific method for reducing the amount of fine bubbles and dissolved gas, for example, there is a method of defoaming by holding the resist solution in a reduced pressure atmosphere. Generally, the resist solution contains a volatile solvent. Therefore, if the vacuum defoaming process is performed for a long time, such a volatile solvent may be evaporated and the viscosity of the resist solution may change. Therefore, when performing the vacuum defoaming treatment, it is preferable to perform the vacuum defoaming treatment while adding a predetermined volatile solvent to the resist liquid so that the viscosity of the resist liquid does not change.

Another method for reducing the number of defects generated when forming a resist film is to use a solvent contained in the resist solution in a heat treatment performed after applying the resist solution to the wafer W and spreading it to a predetermined film thickness. It is a method of setting the heat treatment temperature, the heat treatment time, or the temperature rising pattern according to the amount.
When forming a thin resist film having a thickness of 150 nm or less, a resist solution containing a large amount of a solvent and having a low viscosity is generally used. Conversely, containing a large amount of solvent means that the amount of evaporation of the solvent during heat treatment is large, so if the solvent bumps due to rapid heating,
This may cause pinhole defects in the resist film.

Specifically, after the wafer W is placed on the hot plate which is kept at a constant low temperature, the temperature of the hot plate is continuously and gradually raised, or the temperature is gradually increased stepwise. A method of raising the temperature is preferably used. FIG. 8 shows a prebaking process of a resist film having a film thickness of 80 nm, and a conventional heat treatment method (STD) in which a wafer W is placed on a hot plate held at 180 ° C. and heat treated, and baking is performed at 85 ° C. 6 is a graph showing a comparison of the number of defects of the wafer W when the method is performed later by baking at 180 ° C. (step baking).

As a result of processing five wafers W by each method, although there are variations in the number of defects for each wafer W, the result is that the number of defects in the wafer W subjected to the step baking is small as a whole. . This is considered to be the result of suppressing the generation of pinhole defects due to bumping or the like of the solvent by gently evaporating the solvent.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, for the wafer W, resist coating /
Generally, a scrub cleaning process is performed before being carried into the development processing system 1. The number of defects in the wafer W can also be reduced by variously changing the conditions at this time, such as the number of rotations of the brush, the number of rotations of the wafer W, and the type of cleaning liquid. Further, a predetermined film may be previously formed on the surface of the wafer W before forming the resist film. Further, although the case of forming the resist film has been described in the above embodiment, the present invention can be applied to the case of forming the protective film, the interlayer insulating film, and the like. Furthermore, although the semiconductor wafer is taken as the substrate, the present invention can be applied to other substrates such as a liquid crystal display (LCD) substrate.

[0072]

As described above, according to the present invention, the substrate before the coating film is formed is subjected to a predetermined treatment to reduce the number of defects on the surface of the substrate, thereby forming the film on the surface of the substrate. The number of defects in the coating film can be reduced. Further, by appropriately controlling the conditions for forming the coating film on the substrate, the number of defects generated in the coating film can be suppressed and a high quality coating film can be obtained. As described above, the present invention makes it possible to obtain a coating film of high quality and has a remarkable effect of increasing the reliability of the product.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing an embodiment of a resist coating / developing system.

FIG. 2 is a schematic front view showing an embodiment of a resist coating / developing system.

FIG. 3 is a schematic rear view showing an embodiment of a resist coating / developing processing system.

FIG. 4 is a schematic sectional view showing an embodiment of a resist coating unit (COT).

FIG. 5 is a schematic plan view showing an embodiment of a resist coating unit (COT).

FIG. 6 is an explanatory diagram (graph) showing the relationship between the thickness of a resist film and the number of defects.

FIG. 7 is an explanatory diagram (graph) showing the relationship between the number of defects on the wafer and the resist film.

FIG. 8 is an explanatory diagram (graph) showing the number of defects in the resist film in the conventional heat treatment and the heat treatment by step baking.

[Explanation of symbols]

1; Resist coating / development processing system 48; Holding member 52; Spin chuck 86; Resist nozzle 92: Resist nozzle scan arm 95; resist liquid supply unit 100; Nozzle holder 101; thinner nozzle 122; Rinse nozzle 131; Axis member 132; Cleaning nozzle arm 133; Cleaning nozzle CP; coater cup HP: Hot plate unit COT; resist coating unit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B05D 3/06 102 G03F 7/09 501 G03F 7/09 501 7/38 501 501 7/38 501 H01L 21/30 563 564D 566 F term (reference) 2H025 AA18 AB16 DA17 FA01 2H096 AA25 CA01 DA01 4D075 AC64 AC79 AC91 AC92 AC96 BB21Z BB23X BB46X BB56X BB65X JABBJAJA JA02 JA45 JA04 5102 DA45 5

Claims (5)

[Claims] 1. A method of treating a substrate, which is performed on the surface of a substrate on which a coating film is formed, wherein the surface of the substrate is exposed to ultraviolet rays having a wavelength of 180 nm to 250 nm 30 before the formation of the coating film. Irradiating for 2 to 50 seconds to reduce the number of defects on the surface of the substrate. 2. A method of treating a substrate, which is applied to a surface of a substrate on which a coating film is formed, before forming the coating film, wherein the surface of the substrate is treated with an organic solvent prior to the formation of the coating film. A first step of reducing the defects on the surface of the substrate by contacting with the substrate for a predetermined time, a second step of removing the organic solvent from the surface of the substrate, and a third step of rinsing the substrate, A substrate processing method comprising: 3. A method of treating a substrate, which is performed on the surface of a substrate on which a coating film is formed, wherein the substrate is heated to 400 ° C. to 8 ° C. prior to forming the coating film.
A method for treating a substrate, characterized in that the number of defects on the surface of the substrate is reduced by holding the substrate in an atmosphere of an inert gas in a temperature range of 00 ° C. for 30 seconds to 120 seconds. 4. A coating film forming method for forming a coating film by coating a substrate with a coating liquid, wherein the coating liquid has a fine bubble content adjusted to a certain value or less, or a dissolved gas amount. The coating film forming method is characterized in that the number of defects formed in the coating film is reduced by using a coating liquid adjusted to a certain value or less. 5. A first step of applying a coating liquid to a substrate, a second step of spreading the coating liquid over the entire substrate to adjust the film thickness of the coating film to a predetermined value, and a substrate on which the coating film is formed. A heat treatment is performed at a predetermined temperature, and in the third step, a heat treatment temperature, a heat treatment time, or a heating pattern is set according to the amount of the solvent contained in the coating liquid. A method for forming a coating film.