JPH0465525B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a method of forming a highly accurate resist pattern by controlling the sensitivity of a resist, and a resist processing apparatus for realizing the method.

[Technical background of the invention and its problems]

As the integration density of semiconductor devices, including VLSIs, increases, finer and more precise pattern formation techniques are required. Therefore, in the most advanced field, in the case of a 6-inch square mask or a 5-inch diameter wafer, a dimensional error of, for example, 3б<0.1 [μm] with respect to the average dimension value of the pattern within the substrate surface is required. Furthermore, in a mass production line, speed of the pattern formation process is essential, and high sensitivity of the resist is desired. However, conventionally high-sensitivity resists have poor resolution, making it difficult to obtain the desired pattern dimensional accuracy.On the other hand, high-resolution resists have low sensitivity, making it difficult to form patterns on mass production lines. There were problems such as the inability to achieve high throughput.

FIG. 1 is a flowchart showing a resist pattern forming process according to the prior art. First, a resist is applied to a predetermined thickness on a substrate to be processed by a well-known spin coating method. Next, in order to remove the coating solvent and improve the adhesion between the resist and the substrate,
Using an oven, etc., set the temperature according to the resist.
Bake (prebake) the resist with Tb.
Thereafter, the resist film-coated substrate taken out of the oven is allowed to cool naturally on a support stand in the atmosphere (~1 atm), thereby cooling to room temperature over 20 to 30 minutes. For the resist film that has completed cooling,
Predetermined irradiation amount (exposure amount) depending on the type of resist
Then, electromagnetic waves in a predetermined wavelength range, such as ultraviolet light, or particle beams with a predetermined energy, such as electron beams, are selectively irradiated. Thereafter, a desired resist pattern is formed through a development and rinsing process.

By the way, when the present inventors investigated the temperature distribution of the entire film surface at a certain point in time using an infrared radiation thermometer for the resist film on the substrate to be processed during the natural cooling described above, the results were as shown in Fig. 2. The results were obtained. In this case, the temperature Tb during baking prior to natural cooling was ~160 [°C]. In FIG. 2, the temperature is high (cooling is slow) at the upper central part (point A) of the substrate 21 to be processed with a resist film, and as it progresses downward (point C) through the central region (point B), the temperature increases. is becoming lower (cooling speed is faster). Note that each curve in the figure is an isothermal line.
Figure 3 shows the temperature changes over time at points A, B, and C in Figure 2, with curves 31 and 3
2 and 33 are cooling characteristics corresponding to points A, B, and C, respectively. The maximum temperature difference between point A and point B is about 15 [℃],
The maximum temperature difference between point A and point C was about 30 [°C].
These temperature measurements were performed by bringing a thermocouple into contact with the portion to be measured on the resist film. The reason for this temperature distribution (uneven cooling rate) is that during natural cooling, the substrate to be processed is placed on a support stand, etc., so natural convection in the atmosphere due to heat dissipation occurs along the substrate surface. Possible reasons include that it tends to occur upwards and that heat is easily removed from the lower part of the substrate by the support. In addition, the present inventors focused on the relationship between the temperature distribution during cooling of the substrate to be processed with a resist film and the dimensional accuracy of the resist pattern after irradiation and development processing. When we measured the dimensions of the pattern formed in area C, we found that the pattern B
There is an error of about 0.1 [μm] at point C, and an error of about 0.2 [μm] at point C, so that the temperature distribution during cooling of the resist film-coated substrate and the size distribution of the resist pattern to be formed are completely different through the sensitivity distribution of the resist. I confirmed that it is compatible. Therefore, in order to obtain a highly accurate resist pattern with uniform pattern dimensions, it has been found that uniform cooling that does not cause temperature distribution within the substrate surface after resist baking is essential.

On the other hand, the inventors focused on the relationship between the cooling process of the resist film after baking and the sensitivity of the resist, and as a result of various experiments and research, they found that After baking the film, the temperature of the resist film is first set to Tb.
to an arbitrary intermediate cooling temperature Tm, then
Tm to any final cooling temperature below e.g. room temperature
It has been found that the sensitivity of the resist can be completely controlled with good reproducibility by rapidly cooling it to Tc (Tb≧Tm>Tc). Furthermore, it was found that the resolution of resist patterns formed by controlling these cooling processes was not at all inferior to the pattern resolution of the resist itself. In addition, it has been found that a resist pattern with extremely high dimensional accuracy can be formed by uniformly performing the resist film cooling of Tb→Tm→Tc over the entire substrate surface.

As a method for uniform rapid cooling of the resist film from Tm→Tc→, there is a method in which the entire resist film-coated substrate at an arbitrary temperature Tm is rapidly immersed in a liquid coolant such as water at a temperature Tc (Tm>Tc). This method has already been proposed by the present inventors. However, various trials of this method under atmospheric pressure (~1 atm) revealed that although the resist sensitivity could be controlled with good uniformity and reproducibility, the temperature Tm of the substrate before rapid cooling was lower than the atmospheric pressure (~1 atm) of the liquid coolant for cooling. If the temperature is higher than the boiling point (1 atm), when the baked substrate is immersed in the cooling liquid,
It has been found that a large number of bubbles are generated due to boiling of the liquid, which roughens the surface of the resist film, and as a result, the resist pattern may deteriorate. Furthermore, since conventional resist baking was performed at atmospheric pressure (~1 atm), it took a long time to evaporate the resist solvent, which is the main purpose of baking.

[Purpose of the invention]

An object of the present invention is to provide a resist pattern forming method that can arbitrarily control the sensitivity of a resist to electromagnetic waves or particle beam irradiation without deteriorating resolution, and efficiently and quickly form a highly accurate resist pattern. The object of the present invention is to provide a resist processing apparatus for realizing this.

[Summary of the invention]

The gist of the present invention is to slowly cool the baked resist to a desired temperature Tm, and then rapidly cool it with a cooling liquid, and preferably to create a space in which the cooling liquid is stored so that the boiling point of the liquid is above the temperature Tm. temperature
The purpose is to hold it under a pressure that is higher than Tm. FIG. 4 shows an outline of the resist pattern forming process according to the present invention. First, a resist film is applied and formed on a substrate to be processed. Next, this resist film coated substrate is placed in a container with a predetermined pressure of 1 atmosphere or less, and resist baking is performed at a predetermined temperature Tb for a predetermined time. Next, first cooling is performed to lower the temperature of the substrate from the baking temperature Tb to an arbitrary intermediate cooling temperature Tm (Tb≧Tm). Next, while the substrate temperature is maintained at Tm, the boiling point of the cooling liquid refrigerant at the final cooling temperature Tc provided in the container reaches Tm.
After increasing the pressure in the container as above, the entire substrate is rapidly immersed in the cooling liquid refrigerant to bring the temperature from the intermediate cooling temperature Tm to the final cooling temperature Tc (Tm>Tc). A rapid and uniform second cooling of the temperature is performed continuously. In this case, by arbitrarily changing the rapid cooling temperature difference Tm - Tc during the second cooling, or if the final cooling temperature c is fixed, the intermediate cooling temperature, that is, the rapid cooling start temperature By setting Tm to an arbitrary value, the resist sensitivity finally obtained can be controlled to an arbitrary value. Thereafter, the resist is selectively irradiated with electromagnetic waves in a predetermined wavelength range or particle beams with a predetermined energy, and is developed and rinsed to form a predetermined resist pattern.

That is, in the present invention, a resist pattern is formed by applying a resist onto a substrate to be processed, baking it, cooling it, selectively irradiating the resist with an electromagnetic wave of a predetermined wavelength or a particle beam of a predetermined energy, and performing a development process. In the method for forming a resist, the resist is baked at a predetermined temperature Tb higher than the glass transition temperature Tg of the resist, the substrate is then slowly cooled from the temperature Tb to an arbitrary intermediate temperature Tm, and then the electromagnetic wave or Before irradiation with the particle beam, the resist-attached substrate is immersed in a cooling liquid at a predetermined temperature Tc under a pressure higher than normal pressure and whose boiling point is Tm or higher to rapidly and uniformly cool the resist. This is the method.

The present invention also provides a resist processing apparatus that bakes and then cools a resist coated on a substrate to be processed. A heating chamber that slowly cools the substrate and lowers the temperature of the substrate from the heating temperature Tb to an intermediate temperature Tm, and a heating chamber that is connected to this heating chamber via a gate valve, and the heated and slowly cooled substrate is immersed to cool the substrate. A cooling chamber containing a cooling liquid and maintaining the inside thereof under pressure such that the boiling point of the liquid is equal to or higher than the temperature Tm, and is designed to rapidly cool from the temperature Tm. be.

〔Effect of the invention〕

According to the present invention, the sensitivity of the resist to electromagnetic waves or particle beam irradiation can be arbitrarily set without deteriorating its resolution. Therefore, even a low-sensitivity resist can be made highly sensitive by the method of the present invention without deteriorating its resolution, and the time required for irradiation treatment with electromagnetic waves or particle beams can be shortened. Moreover, according to the present invention, the resist film after baking is cooled uniformly over the entire film, and the resist film surface does not become rough, so that dimensional variations can be reduced over the entire substrate to be processed. It is possible to form a resist pattern with a small number of extremely high precision.

Furthermore, by performing resist baking under reduced pressure, not only the cooling treatment time but also the resist baking treatment, which conventionally required a long time after forming a resist coating film, can be significantly shortened. For example, the processing capacity of about 10 substrates per hour in the past has increased to over 300 substrates per hour using the method of the present invention.
Work efficiency is greatly improved.

[Embodiments of the invention]

<Example 1> In the present invention, a method for forming a resist pattern using a positive electron beam sensitive resist made of poly(2,2,2-trifluoroethyl-α-chloroacrylate) will be described. First, the resist described above is applied onto a substrate to be processed by a well-known spin coating method. The coating film thickness may be, for example, about 0.3 to 1 [μm], but here it was set to 0.8 [μm]. Although there are various types of substrates to be processed, such as semiconductor wafers and glass substrates, a glass substrate with a metal film was used here. Next, using a resist processing device as described below,
The resist film was baked and cooled. The bake temperature Tb is the glass transition temperature Tg of the above resist.
(140-190 [℃] exceeding (~133℃) is sufficient, but
Here, the temperature was set to 180 [℃]. Further, the pressure surrounding the resist film-coated substrate to be processed during baking was approximately 0.1 atm, and resist baking was performed in this state for approximately 10 minutes. Although the baking time can be further shortened, it was set to 10 minutes in this example. Next, the temperature of the resist film coated substrate is set to an arbitrary intermediate cooling temperature Tm.
After lowering the temperature to (Tb≧Tm), the pressure around the substrate was increased while maintaining the temperature of the resist film-coated substrate at Tm. After the ultimate pressure reaches approximately 10 atmospheres, the predetermined final cooling temperature Tc under the same pressure (Tm>Tc)
The entire resist film-coated substrate to be processed at a temperature of Tm was immersed rapidly (within 3 seconds) into cooling water to uniformly and rapidly cool the resist. In this example, the intermediate cooling temperature (rapid cooling start temperature) Tm is 180~
The temperature was varied in steps of 10 [°C] within a range of 40 [°C]. Also,
Room temperature (25°C) was chosen as the final cooling temperature Tc.
Figure 5 shows the intermediate cooling temperature, that is, the rapid cooling start temperature Tm.
shows the temperature change Tb → Tm → Tc during cooling of the substrate to be processed with the resist film when the temperature is, for example, 150 [°C], and the resist surface on the substrate to be processed is A, These are the results of measuring temperature changes in three regions substantially equivalent to regions B and C. Above A, B,
C The characteristics corresponding to temperature changes in each region are shown in curve 5.
1, 52, and 53, uniform cooling is achieved over the entire area (Tb→Tc) compared to the cooling characteristics of the conventional method shown in Fig. 3, and especially uniform and rapid cooling is performed in the cooling region of Tm→Tc. It is clearly seen that Such uniform (Tb→Tm→Tc) and rapid (Tm→Tc) cooling was similarly observed for any other Tm. Note that the cooling time from each Tm to Tc after the substrate to be processed was immersed in the cooling water was ~3 seconds or less in all cases of this example.
Sensitivity to electron beams (predetermined development conditions) for each resist sample that has gone through the above baking and cooling process (Tb = 180°C → Tm → Tc = 25°C) when the intermediate cooling temperature, that is, the rapid cooling start temperature Tm, is varied. As a result of investigating the amount of electron beam irradiation when the remaining thickness of the resist film becomes zero (see below), the characteristics shown in FIG. 6a were obtained. The characteristics shown in Figure 6(a) apply to the resist film after each of the above baking and cooling processes.
After irradiation with an electron beam of 20 [keV], development was performed at room temperature for 10 minutes using a developer solution of methyl isobutyl ketone (MIBK): isopropyl alcohol (IPA) = 7:3.
It was then rinsed with IPA solution for 30 seconds. As shown in FIG. 6a, in the resist cooling process from Tb→Tm→Tc, the intermediate cooling temperature, that is, the rapid cooling start temperature Tm, is approximately equal to the glass transition temperature Tg (~133°C) of the resist. A wide range of changes appears in resist sensitivity. High resist sensitivity is obtained in the Tb≧Tm>Tg region, and as Tm approaches Tb, the sensitivity increases, and the maximum resist sensitivity is ~1.2 × 10 [C/
cm ² ] is obtained. In the Tg>Tm>Tc (=25°C) region, the resist sensitivity decreases as the rapid cooling start temperature Tm decreases, and the sensitivity decreases to ~8×10 ^-6 [C/cm ² ] compared to conventional natural cooling. Get closer.

On the other hand, vacuum baking similar to the process described above,
Using a 20 [keV] electron beam lithography system, the entire surface of the resist film coated substrate (6-inch □ glass substrate with metal film), which has been subjected to pressure boost cooling, except for the peripheral area, is irradiated with a dose corresponding to each of the above sensitivities. MIBK/IPA (=7/
3) Development and IPA rinsing were performed to form a resist pattern. These resist patterns were clean and had good pattern resolution. In addition, as a result of measuring and evaluating the dimensional accuracy of resist patterns with line widths in the range of 0.5 to 2.0 [μm], for example,
All of the resist patterns in each case had high precision and satisfactorily satisfied the in-plane dimensional variation error of 3б<0.1 [μCm].

<Example 2> In this example, polymethyl methacrylate was used as a resist. Other conditions were substantially the same as in Example 1 described above, but the baking temperature Tb was set at 170 [°C], which exceeded the glass transition temperature Tg of the present resist ~110 [°C]. The pressure around the substrate during resist baking was 0.3 atm, and the resist baking time was 10 minutes. The pressure around the substrate during cooling of the resist film is approximately 8 atmospheres, and the baking temperature Tb = 170 [℃]
to the final cooling temperature through various intermediate cooling temperatures Tm
The resist was cooled to Tc=25 [°C]. Intermediate cooling temperature, that is, rapid cooling start temperature Tm is 170 to 40
The temperature was varied in steps of 10 [°C] within the [°C] range. As in Example 1, the liquid refrigerant for final cooling was at room temperature of 25°C.
It is water at [℃]. Uniform rapid cooling from Tm to Tc (=25°C) is achieved by rapidly (within 3 seconds) immersing the entire resist film coated substrate at temperature Tm into water at temperature Tc (=25°C). I turned over and went.
After irradiating each resist sample with a 2 [keV] electron beam after undergoing the various cooling processes described above, it was heated for 13 minutes at room temperature.
After MIBK development and 30 seconds of IPA rinsing,
The sensitivity characteristics of each were investigated. FIG. 6b shows the change in resist sensitivity with respect to the intermediate cooling temperature, that is, the rapid cooling start temperature Tm. In this example as well, a wide range of sensitivity changes appears in the region where the rapid cooling start temperature Tm is approximately equal to the resist glass transition temperature Tg=110 [° C.]. Tb≧Tm＞Tg
In this region, the higher the Tm, the higher the resist sensitivity, reaching a sensitivity of ~2×10 ⁻⁶ [C/cm ² ]. Tg>
In the Tm>Tc (=25° C.) region, the lower the Tm, the lower the resist sensitivity becomes, approaching the sensitivity of conventional natural cooling of ~1×10 ⁻⁵ [C/cm ² ].

On the other hand, vacuum baking similar to the process described above,
To the entire surface of a substrate with a resist film (6-inch □ glass substrate with metal film) that has been subjected to pressure boost cooling, except for the peripheral area.
Using a 20 [keV] electron beam lithography system, selective pattern irradiation was performed at a dose corresponding to each of the above resist sensitivities, and a resist pattern was formed by performing MIBK development at room temperature and IPA rinsing treatment.
The resist patterns were clean and had good pattern resolution over all substrates. In addition, in this example, as a result of measuring and evaluating the dimensional accuracy of the resist pattern in the line width range of 0.5 to 2.0 [μm], the resist pattern in all cases was highly accurate, and the dimensional fluctuation error within the substrate surface was All 3б<
It was 0.1 [μm].

The main purpose of the present invention is to speed up resist processing and improve the precision of resist patterns by baking the resist film on the substrate to be processed and quickly and uniformly cooling it by increasing the pressure. In the process of cooling the resist film after baking from the temperature Tb to the final cooling temperature Tc, an arbitrary intermediate cooling temperature Tm (Tb≧Tm＞Tc) is set, and with Tm as the rapid cooling start temperature, the substrate with the resist film is heated to the final cooling temperature Tc. The purpose is to arbitrarily control the sensitivity of the resist by rapidly immersing and cooling it in a liquid coolant. Therefore, by using the method of the present invention, the sensitivity of the resist can be arbitrarily and uniformly set to match the performance of various resist irradiation (exposure) devices, for example.

In the above embodiments, examples of resist pattern formation using two types of resists have been described. The development and rinsing methods, baking temperature, etc. are not limited to the examples described above, and various known materials, resist solvents, development, rinsing methods, and baking temperatures may be used in this book. It has been confirmed that the various effects of the invention are achieved. It is necessary to set the resist film and the pressure during baking (1 atm or less), taking into account the baking temperature Tb, the vapor pressure of the solvent, etc., so as not to cause, for example, solvent bumping during resist baking. . Needless to say, from the viewpoint of speeding up solvent evaporation, it is desirable to lower the pressure as much as possible. Conversely, once the baking pressure is determined, the baking time can be arbitrarily set to a short time within a range that substantially evaporates the resist solvent and achieves sufficient adhesion of the resist to the substrate. In addition, in the above example, water was used as the liquid that is a cooling medium for the resist after baking, but water has a large heat capacity (specific heat) and does not substantially cause physical or chemical changes to the resist during immersion. Any liquid refrigerant (for example, higher alcohol, glycerin, etc.) may be used. Furthermore, the pressure during the cooling process should be at least as high as the resist bake temperature.
It may be set to any value as long as it is equal to or higher than the vapor pressure of the liquid refrigerant at Tb.

In addition, as mentioned in the above example, according to the research results of the present inventors, the baking temperature of the resist is
Tb and intermediate cooling temperature (rapid cooling start temperature) Tm
exceeds the glass transition temperature Tg of the resist, the resist sensitivity can be significantly improved by rapidly immersing the resist in a liquid coolant at a temperature Tc below Tg (Tb≧Tm＞Tg＞Tc). It has been confirmed that this can be achieved. Furthermore, it has been confirmed that the lower the temperature Tc of the coolant is in the region below Tg, the more the resist sensitivity after rapid resist cooling increases. Therefore, Tb≧Tm＞
In the range that satisfies the relationship Tg > Tc, the intermediate cooling temperature,
That is, by selecting arbitrary values for the rapid cooling start temperature Tm and the temperature Tc of the liquid coolant for cooling the resist, it is possible to further expand the range of increasing the sensitivity of the resist.
In addition, the time required to immerse the entire resist film-coated substrate into the liquid coolant at the intermediate cooling temperature Tm to the final cooling temperature Tc is the temperature of the substrate that occurs when the substrate is moved from baking to cooling. In order to suppress unevenness in the drop (which induces unevenness in resist sensitivity), the shorter the better, preferably 5 to 6 seconds or less, preferably 3 seconds or less. Furthermore, as for the resist irradiation (exposure) method, the effects of the present invention can be obtained by using, in addition to the above-described electron beam, electromagnetic waves in a predetermined wavelength range such as light beams, X-rays, and ion beams, or particle beams with a predetermined energy.

<Embodiment 3> Next, an example of a resist processing apparatus suitable for implementing the dimensions of the present invention will be described with reference to FIG. 7. The apparatus shown in FIG. 7 fully automatically processes a series of steps from resist coating to a substrate to be processed to before irradiation or exposure. First, a substrate to be processed 71a to be coated with a resist is stored in a cassette 72a in advance, and is conveyed by a belt conveyor 73a to a predetermined position before resist coating according to a predetermined conveyance sequence. Next, a vacuum chuck conveyor 74 having a rotation/vertical movement mechanism is provided.
The substrate to be processed 71a is transferred onto the resist coating rotary table 75 by step a. Next, the resist dissolved in the solvent is dropped onto the substrate to be processed 71b from the resist dropping nozzle 76, and the substrate to be processed 71b is rotated by the rotating table 75. As a result, the substrate to be processed 71b
A resist film of a predetermined thickness is formed on b. During resist rotation coating, the substrate to be processed 71b is placed on the rotating table 75.
It is fixed by means such as a vacuum chuck. Next, the resist-coated substrate 71b is rotated and
A vacuum chuck carrier 74b having a vertical and horizontal movement mechanism is used to transfer and place the substrate to be processed on a substrate support 78 in a resist vacuum bake/boost cooler 77, which is the core of the resist processing apparatus of the present invention. . All of the above treatments are performed under atmospheric pressure (~1 atm). The vacuum bake/boost cooler 77 is comprised of a bake chamber (heating chamber) 80 containing a heater 79 and a cooling chamber 82 containing a cooling liquid refrigerant (for example, water) 81. There is an opening between the baking chamber 80 and the cooling chamber 82, which is large enough to allow the substrate support 78 on which the substrate to be processed 71c is placed to pass, and the opening is opened and closed by a gate valve 83. An opening is provided on the bake chamber 80 side to serve as an entrance/exit for loading and unloading substrates, and a valve 8 is provided.
4a and 84b are used to open and close them. Further, on the bake chamber 80 side, a pressure reducing pipe 85a, a pressure increasing pipe 85b, a leak pipe 85c, etc. are provided, and on/off valves 86a, 8
6b and 86c. Further, on the side of the cooling chamber 82, an injection pipe 87a and a discharge pipe 87b for liquid refrigerant are provided, each having an on-off valve 88a, 88b. The temperature Tc of the liquid refrigerant 81 is set in advance to a predetermined value using a liquid temperature regulator (not shown) placed in the vacuum bake/boost cooler 77. When all the above valves are closed, the bake chamber 80
Both the cooling chamber 82 and the cooling chamber 82 are completely sealed. When the substrate 71c to be processed is transferred onto the substrate support 78 by the transfer device 74b, the valve 84 is
Only valve a is open and all other valves are closed. Further, at this point, the pressure inside the baking chamber 80 and the cooling chamber 82 is atmospheric pressure (~1 atmosphere). When the substrate 71c to be processed is transferred onto the substrate support 78, the valve 84a is closed and the bake chamber 80 is closed.
is sealed. Next, the valve 86a is opened and the pressure reducing pipe 85a is passed through to bring the inside of the bake chamber 80 to a predetermined pressure (1 atmosphere or less). When the inside of the bake chamber 80 reaches a predetermined pressure state, the substrate support 78 is moved so that the resist surface on the substrate 71c and the heater 79 face each other substantially in parallel with a predetermined interval. Since it is necessary to bake the opposing resist surfaces at a uniform temperature, the shape of the heater 79 is devised so that a substantially planar heating source can be obtained. Next, heater heating is started and the resist is baked at a predetermined temperature Tb. During resist baking, there is a risk that the pressure inside the baking chamber 80 will rise above a predetermined value due to evaporation of the solvent in the resist film.
The solvent vapor is exhausted through a to maintain the pressure inside the bake chamber 80 at a predetermined value. After baking the resist at a predetermined temperature Tb for a predetermined time, the heater heating is automatically adjusted so that the temperature of the resist film surface reaches an arbitrary intermediate cooling temperature Tm, and the temperature Tm (Tb ≧Tm). When the temperature of the resist film-coated substrate stabilizes at a predetermined Tm value, the valve 86a is closed while heating and the position of the substrate support remain as they are so as not to change the Tm value. Then,
The valve 86b is opened and gas is introduced into the bake chamber 80 through the pressure increasing pipe 85b. Bake room 80
When the internal pressure is increased to approximately atmospheric pressure (~1 atmosphere), the valve 83 is opened, and the pressure increase continues until the baking chamber 80 and the cooling chamber 82 reach a predetermined pressure value under the same pressure. The substrate to be processed is kept at a predetermined temperature in a bake chamber until the pressure is increased to a predetermined pressure.
Retained by Tm. Bake chamber 80 and cooling chamber 8
When the pressure in step 2 reaches a predetermined value, the valve 86b is closed, the substrate support 78 is rapidly lowered, and the entire resist film-coated substrate 71c is rapidly transferred into the liquid coolant 81 at the predetermined temperature Tc in the cooling chamber 82. It is immersed and subjected to a second cooling (Tm>Tc). At this time, the pressure of the liquid refrigerant is set sufficiently high so that boiling of the refrigerant does not occur. At this point, the heater heating in the bake chamber 80 is stopped, but depending on the structure of the bake chamber 80, the heater heating may be continued in order to perform the baking process of the subsequent resist film coated substrate without interruption. can. Next, the substrate support 7
8 moves upward, and the substrate to be processed 71c is lifted out of the liquid coolant 81 and transferred to a predetermined position in the baking chamber. Next, the leak valve 86c is opened and the bake chamber 8 is passed through the leak pipe 85c.
0 and the pressure in the cooling chamber 82 is returned to atmospheric pressure (~1 atm). When the pressure in the baking chamber 80 and the cooling chamber 82 reaches approximately atmospheric pressure (~1 atm), the valve 83 is closed.
and valve 86c is closed, then valve 84
b can be opened. All steps from this point on are done under atmospheric pressure. Next, the cooled resist film-coated substrate 71c is taken out of the vacuum bake/boost cooler 77 through the opening of the valve 84b by a vacuum chuck carrier 74c having a rotating, vertical, and horizontal movement mechanism. , and placed on the drying rotary table 89. The substrate to be processed 71d is rotated by the rotating table 89, and as a result, the liquid refrigerant adhering to the substrate to be processed 71d is scattered and forced drying is performed.
During rotation drying, the substrate 71d to be processed is fixed onto the rotating table 89 by means such as a vacuum chuck. The dried substrate 71d is then transferred to a predetermined position on the belt conveyor 73b by a vacuum chuck carrier 74d having a rotation/up-and-down mechanism.
The substrate 71e to be processed, which has been subjected to resist coating, baking, cooling, and drying, is stored in a cassette 72b by a belt conveyor 73b in a predetermined sequence. The process performed by the resist processing apparatus of the present invention is completed when the above-described processing is sequentially performed on all the substrates to be processed.

Note that this equipment uses a single-wafer processing method, so depending on the situation, the processing time for the vacuum baking and boosting cooler sections may become long, which may upset the balance of processing times with other sections. There may also be cases where high throughput cannot be achieved. In such a case,
The vacuum baking and boosting coolers are arranged, for example, in a circle or in parallel, and an appropriate delay time is set in consideration of the processing time of other parts and the baking/cooling processing time, and the process is carried out in a circle or in parallel. By performing the baking and cooling processes, it is possible to increase the throughput of the entire apparatus. Furthermore, it is also possible to increase the size of the vacuum bake/boost cooler within a predetermined allowable range, and apply a batch processing method to only that part. In addition, in the vacuum baking and pressure boosting coolers mentioned above, the pressure and temperature of the baking chamber and cooling chamber are adjusted depending on the solvent and baking temperature of the resist to be processed and the type of cooling refrigerant used. It is desirable that the mechanical strength, airtightness, and heat resistance of the container be sufficiently high. Alternatively, the heater for resist baking may be taken out of the baking chamber and the resist may be heated from outside through an infrared transmitting material. In this case, the infrared transmitting portion will be provided at a predetermined location on the equipment constituting the baking chamber of the baking/cooling device, but it goes without saying that sufficient consideration must be given to mechanical strength and airtightness. Also, from the baking temperature Tb to the rapid cooling start temperature
The first cooling to Tm may proceed in parallel with the process of increasing the pressure in the bake/cooler from a reduced pressure state to a predetermined pressure after resist baking.
In order to quickly perform the first cooling, a liquid refrigerant at an intermediate cooling temperature Tm may be further added to the bake cooler to perform rapid cooling from the bake temperature Tb to Tm. Of course, it is important to perform rapid cooling in this case after adjusting the pressure state so that the boiling point of the liquid refrigerant exceeds Tm. The transport form of the substrate to be processed does not need to be limited to the above-mentioned form, and the most suitable form for the processing apparatus may be introduced.

In short, the resist pattern forming method and resist processing apparatus of the present invention can be modified and applied in various ways without departing from the gist thereof.

[Brief explanation of drawings]

Figure 1 is a flowchart schematically showing a conventional resist pattern forming process, Figure 2 is a schematic diagram showing isothermal curves of temperature changes at various points on the substrate after resist baking in the conventional process; Figure 3 is a characteristic diagram showing the state of the temperature change as a time vs. temperature curve;
FIG. 4 is a flowchart schematically showing the resist pattern forming process according to the present invention, FIG. 5 is a characteristic diagram showing substrate temperature changes during resist cooling in the present invention, and FIGS. 6(a) and (b) are FIG. 7 is a characteristic diagram regarding the resist sensitivity obtained by the method of the present invention, and is a schematic configuration diagram showing an example of a resist processing apparatus suitable for carrying out the method of the present invention. 71a to 71e...Substrates to be processed, 72a to 72
b...cassette, 73a, 73b...belt conveyor, 74a to 74d...vacuum chuck conveyor,
75...Rotating table, 76...Resist dripping nozzle,
77... Decompression bake/boost cooler, 78... Substrate support, 79... Heater, 80... Bake chamber,
81... Liquid refrigerant, 82... Cooling chamber, 83... Opening/closing valve, 84a, 84b... Opening/closing valve, 85
a...Pipe for pressure reduction, 85b...Pipe for pressure increase, 85c...
...Leak pipe, 86a-86c...Opening/closing valve,
87a...refrigerant injection pipe, 87b...refrigerant discharge pipe,
88a, 88b...opening/closing valve, 89...rotating table.

Claims (1)

[Scope of Claims] 1. By applying a resist onto a substrate to be processed, baking it, cooling it, and then selectively irradiating the resist with an electromagnetic wave of a predetermined wavelength or a particle beam of a predetermined energy, and performing a development process. In the method of forming a resist pattern, the resist is baked at a predetermined temperature Tb higher than the glass transition temperature Tg of the resist, and then the substrate is heated to the temperature Tg.
The cooling liquid is slowly cooled from Tb to an arbitrary intermediate temperature Tm, and then, before the electromagnetic wave or particle beam irradiation, the cooling liquid is heated to a predetermined temperature Tc under a pressure higher than normal pressure and whose boiling point is higher than Tm. Immerse the resist-coated substrate and cool the resist to the final cooling temperature Tc.
A resist pattern forming method characterized by rapid cooling until the temperature reaches 100. 2 The above temperatures Tg, Tb, Tm, Tc are Tb>Tm
The resist pattern forming method according to claim 1, characterized in that the following relationship is satisfied: >Tg>Tc. 3. The resist pattern forming method according to claim 1, wherein the resist is baked under a pressure that is lower than normal pressure. 4. The resist pattern forming method according to claim 3, wherein the substrate is immersed in the cooling liquid within 3 seconds from the end of slow cooling of the resist. 5. The resist pattern forming method according to claim 1, wherein baking and slow cooling of the resist are performed in the same heating chamber. 6. In a resist processing apparatus that bakes and then cools the resist coated on the substrate to be processed, the substrate is accommodated and heated to a temperature Tb higher than the glass transition temperature Tg of the resist under a pressure lower than normal pressure. , a heating chamber for slowly cooling the heated substrate and lowering the temperature of the substrate from the heating temperature Tb to an intermediate temperature Tm; and a heating chamber connected to this heating chamber via a gate valve, in which the heated and slowly cooled substrate is immersed. A cooling liquid for cooling the substrate is contained, and the boiling point of the liquid is at a temperature higher than normal pressure.
A resist processing apparatus characterized by comprising a cooling chamber that is maintained under the above pressure.