JP3192250B2 - Method for developing semiconductor substrate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for forming a pattern in photolithography, and more particularly to a method for controlling the temperature of a semiconductor substrate on which a resist film is formed and a developing solution when developing the resist film.

[0002]

2. Description of the Related Art In order to improve the degree of integration of electric circuits formed on a semiconductor substrate, the line width of a circuit pattern has been reduced. In line with this, the line width of a pattern formed by exposing and developing a resist film on a semiconductor substrate is becoming narrower.

When developing a resist film on which a pattern has been exposed with an organic solvent-based developer, the temperature of the developer affects the line width of the pattern. Therefore, temperature control during development is important for forming a pattern with high precision. Therefore, conventionally, before the development, the temperature of the semiconductor substrate on which the resist film is formed is approached to the set temperature of the developing solution, and then the developing process is performed, and the temperature of the atmosphere surrounding the developing tank is also adjusted.

FIG. 4A is a cross-sectional view when a semiconductor substrate is mounted on a constant temperature plate, and FIG. 4B is a plan view at that time. In the figure, reference numeral 40 denotes a constant temperature plate, which is controlled by a heating wire 41 embedded therein so that a set temperature is maintained. 42 is a transfer arm and a semiconductor substrate
Grab 43 and hold and move.

FIG. 5 is a cross-sectional view of a conventional developing device, and portions corresponding to FIG. 4 are denoted by the same reference numerals. In the figure, reference numeral 50 denotes a developing tank, and a hollow portion 51 for flowing circulating water is formed at the bottom. By making the temperature of the circulating water the same as the set temperature of the developer, the temperature of the developer is stabilized. Reference numeral 52 denotes a chamber that covers the top and side surfaces of the developing tank 50, and reference numeral 53 denotes a bottom plate that covers the bottom of the developing tank 50. Reference numeral 54 denotes a transfer port opened on a side surface of the chamber 52 for entering and exiting the semiconductor substrate 43 held by the transfer arm 42, and a shutter 55
It is opened and closed by. Reference numeral 56 denotes a chuck for fixing the semiconductor substrate 43, and a rotary shaft 57 is attached to the bottom of the chuck. The rotating shaft 57 penetrates a hole provided on the bottom of the developing tank 50 and a hole provided on the bottom plate 53, and a motor 58
Is bound to. Reference numeral 59 denotes a pipe for flowing a developer into the developing tank 50. Reference numeral 60 denotes a nozzle for spraying a cleaning liquid onto the semiconductor substrate 43 fixed to the chuck 56. Reference numeral 61 denotes an air outlet for sending temperature-controlled air into the chamber 52, and reference numeral 62 denotes an exhaust outlet for discharging air from the chamber. From the outlet 62, the developer is also discarded.

Next, a method of developing a resist film using the constant temperature plate 40 and a developing device will be described. A resist film formed on the upper surface of the semiconductor substrate 43 in advance has a line width of, for example, 2 μm.
The m test patterns are exposed. This semiconductor substrate 43
Used is a long square having a side length of 5 inches. For example, when the developing solution is used at 25 ° C., both the room temperature in the chamber 52 and the temperature of the constant temperature plate 40 are set to a temperature at which the substrate becomes 25 ° C. Then, the semiconductor substrate 43 is placed on the constant temperature plate 40, and the substrate temperature is brought close to 25 ° C.

Next, the semiconductor substrate 43 is lifted from above the constant temperature plate 40 by holding the corner of the semiconductor substrate 43 with the transfer arm 42, and the shutter 55 of the developing device is opened. Then, the semiconductor substrate 43 is placed and fixed on the tick 56 by the transfer arm 42, and the shutter 55 is closed after the transfer arm is taken out of the chamber 52. Here, the cleaning liquid is ejected from the nozzle 60 to clean the semiconductor substrate 43. Subsequently, the motor 58
The substrate 43 is rotated to dry the substrate surface. At the end of this drying, the temperature of the substrate 43 is, for example, 14 ° C.

Next, the shutter 55 is opened again and the transfer arm
The substrate 43 is placed on the constant temperature plate 40 by 42, and the shutter is closed. Therefore, the temperature of the semiconductor substrate 43 is raised by the constant temperature plate 40 and approaches the temperature of the constant temperature plate.
FIG. 6 shows changes in the surface temperature of the central portion and the peripheral portion of the substrate 43 at this time. The horizontal axis of this characteristic is the elapsed time after the substrate 43 goes out of the chamber 52, and the vertical axis is the surface temperature of the substrate. After a lapse of time that the temperature of the substrate 43 approaches the temperature of the developing solution, the shutter 55 is opened again, and the substrate 43 on the constant temperature plate 40 is transported into the developing tank 50 by the transport arm 42, and the shutter is opened. close. Next, a developing solution at 25 ° C. is poured into the developing tank 50 through a pipe 59 to develop the resist film on the substrate 43. At the time of this development, the temperature of the atmosphere in the chamber 52 is stabilized at 25 ° C. by blowing air from the blower port 61, and the temperature of the developing solution in the developing tank 50 is circulated through the cavity 51. Note that the developing solution may be poured into the developing tank 50 before the substrate 43 is transported.

FIG. 7 is a plan view showing the variation of the line width of the test pattern in the plane of the substrate 43 when the development is started when the elapsed time is 40 seconds. This variation is based on the line width at the center of the substrate 43. The variation becomes larger as approaching the peripheral portion, and is about 0.1 μm at the maximum. The maximum variation of the line width when the development is started when the elapsed time is 70 seconds or 100 seconds is as shown in FIG. As can be seen from FIG. 6, the substrate temperature approaches the developer temperature as the elapsed time becomes longer, so that the maximum variation in line width becomes smaller as shown in FIG. However, when the elapsed time is 100 seconds, the substrate temperature is substantially the temperature of the developing solution. Therefore, even if the elapsed time is 100 seconds or more, the maximum variation in the line width does not become small.

[0010]

However, since the developing solution in the developing tank 50 is an organic solvent which is easily vaporized, the circulating water alone suppresses the influence of heat of vaporization and stabilizes the temperature of the developing solution as described above. It is difficult to let. Further, even if the semiconductor substrate 43 is set to the same temperature as the developer in the constant temperature plate 40,
There is a problem that the temperature of the substrate changes while being transported from the constant temperature plate to the developing tank 50, and a difference occurs between the temperature of the developing solution and the temperature of the substrate, thereby increasing the in-plane variation of the pattern. As described above, conventionally, it has been difficult to develop a highly accurate pattern because the temperature of the developing solution is not sufficiently stabilized and the temperature of the substrate is not sufficiently controlled.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to suppress the generation of heat of vaporization of a developer and to develop a highly accurate pattern by suppressing a change in the substrate temperature during the transfer of the substrate. An object of the present invention is to provide a method for developing a semiconductor substrate .

[0012]

[0013]

According to the present invention, there is provided a method for developing a semiconductor substrate, comprising the steps of: setting a semiconductor substrate on which a film to be developed is formed to a desired temperature; And a step of transporting the developing tank to the developing tank in which the developing solution is contained, and a step of closing the developing tank.

[0014]

[0015]

According to the above-described developing method, the temperature difference between the developing solution and the substrate caused by a change in the substrate temperature during the transport of the substrate can be suppressed because the constant temperature plate is transported together with the substrate. The developer is sealed to suppress generation of heat of vaporization of the developer.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 shows a developing method according to an embodiment of the present invention .
FIG. 2 is a cross-sectional view illustrating a configuration of a pair of upper and lower constant temperature plates and a transfer arm of a developing device , and FIG. 2 is a plan view of an upper constant temperature plate and a transfer arm.

In the figure, reference numeral 10 denotes a disk-shaped upper constant temperature plate, 11 denotes a rectangular lower constant temperature plate, and a heating wire 12 is buried in each of them to maintain a constant temperature higher than the temperature of the atmosphere. It has become. Further, instead of embedding the heating wire 12, the temperature of the thermostatic plate may be controlled by passing temperature-controlled circulating water or a gaseous medium into the thermostatic plate 10.

Reference numeral 13 denotes a transfer arm for holding a corner of the semiconductor substrate 14. Two holes 15 are opened in the upper constant temperature plate 10, and the transfer arm 13 passes through each hole, so that the upper constant temperature plate can move up and down with respect to the two transfer arms.

On the other hand, each transfer arm 13 is provided with a claw 16 near the tip end for holding the semiconductor substrate 14.
14 and upper constant temperature plate 10 are parallel and 0.05m
A gap of m to 5 mm is formed. The distance of the gap is determined so that convection does not occur between the upper constant temperature plate 10 and the semiconductor substrate 14 and the resist film on the semiconductor substrate is not damaged by the contact between the upper constant temperature plate and the semiconductor substrate. Although the upper constant temperature plate 10 is formed of ceramic, the surface cannot be made flat like the semiconductor substrate 14. For this reason, the semiconductor substrate 14 and the constant temperature plate 10 come into contact with each other unless there is a certain gap. Therefore, if the constant-temperature plate 10 is made by attaching a heating wire on a film to one surface of the semiconductor substrate, and the semiconductor substrate 14 is opposed to the surface on which the heating wire is not attached, the above-described distance can be reduced. It is possible.

A windshield 17 wider than the above-mentioned gap is attached to the periphery of the upper constant temperature plate 10 at right angles to the lower surface of the plate. This windshield 17 is used for the transfer arm 13
When the semiconductor substrate 14 moves in the left-right direction, air flows between the upper constant temperature plate 10 and the semiconductor substrate 14 to prevent the temperature of the semiconductor substrate 14 from changing. Further, an infrared temperature sensor 18 is attached to the upper constant temperature plate 10 so that the surface temperature of the semiconductor substrate 14 can be measured and the infrared temperature sensor 18 does not contact the substrate 14. The infrared sensor 18 may be attached to the transfer arm 13.

FIG. 3 shows a developing method according to an embodiment of the present invention.
For an illustration for describing a cross-sectional view of the developing device, FIG. 5 shows a different conventional ones is newly provided is the upper constant temperature plate 10, the transfer arm changes to the transfer arm 13 And the others are the same.
Therefore, in FIG. 3, the portions corresponding to those in FIG. 5 are denoted by the same reference numerals.

The diameter of the upper constant temperature plate 10 is
The transfer arm 13 is larger than the diameter of the opening of the semiconductor substrate.
When 14 is placed on the chuck 56, it serves as a lid for the developing tank. In addition, the semiconductor substrate 14 is
Is moved down onto the chuck 56 in the developing tank 50, the upper constant temperature plate 10 is hooked on the upper end of the developing tank. However, since the transport arm and the upper constant temperature plate are not fixed, the transport arm can be lowered as it is. Also, the pipe 59 into which the developing solution flows into the developing tank 50 becomes an obstacle when the developing tank 50 is covered with the upper constant temperature plate 10, so that the pipe 59 can be slid with respect to the chamber 52 so as to be able to retreat from the developing tank. It is.

Next, using the developing device having the above structure,
A method for developing a resist film formed on a semiconductor substrate will be described. First, a test pattern having a line width of, for example, 2 μm is exposed on a resist film formed on the upper surface of the semiconductor substrate 14 in advance. As this semiconductor substrate 14, a square substrate having a side length of 5 inches is used. Then, in order to use the developing solution at 25 ° C., the room temperature in the chamber 52 and the temperatures of the upper constant temperature plate 10 and the lower constant temperature plate 11 are set to 25 ° C. Then, the semiconductor substrate 14 is gripped by the transfer arm 13 and placed on the lower constant temperature plate 11 so that the substrate temperature approaches 25 ° C.

Next, the semiconductor substrate 14 is lifted from above the lower thermostatic plate 11 by holding the corner portion of the semiconductor substrate 14 with the transfer arm 13 and the shutter 55 of the developing device is opened. And
After retracting the pipe 59 from above the developing tank 50, the transfer arm
At 13, the semiconductor substrate 14 is placed on the chuck 56 and fixed. Then, after the transfer arm 13 is moved out of the chamber 52, the shutter 55 is closed. Here, the cleaning of the semiconductor substrate 14 is performed by spraying a cleaning liquid, for example, isopropyl alcohol at 25 ° C. from the nozzle 60 at a rate of 140 cc / min for 30 seconds. Subsequently, the semiconductor substrate 14 is rotated by the motor 58 at a speed of, for example, 1000 rpm for 60 seconds to dry the substrate surface. At the end of this drying, the temperature of the substrate 14 is, for example, 14 ° C.

Next, the shutter 55 is opened again to move the transfer arm.
The semiconductor substrate 14 is placed on the constant temperature plate 11 by 13 and the shutter is closed. At this time, since the upper constant temperature plate 10 is attached to the transfer arm 13, the semiconductor substrate 14 is sandwiched between the upper and lower constant temperature plates. Therefore, the temperature of the semiconductor substrate 14 rises faster than when the temperature of the semiconductor substrate is raised only by the conventional lower constant temperature plate. Then, the surface temperature of the semiconductor substrate 14 is detected by the infrared sensor 18 attached to the upper constant temperature plate 10, and the detected temperature is in a specified temperature range of about 25 ° C., for example, 24.9 to 2
Wait to enter 5.0 ° C. While waiting for the temperature of the semiconductor substrate 14 to rise, the pipe 59 is moved to the developing tank 50, and the developing solution whose temperature has been adjusted to 25 ° C. is poured into the developing tank, and the pipe is retracted from the developing tank. At this time, the amount of the developing solution to be poured is determined when the semiconductor substrate 14 is put into the developing tank in order to prevent dirt attached to the plate 10 from entering the developing tank when the developing tank 50 is covered with the upper constant temperature plate 10. Not to overflow. Further, circulating water at 25 ° C. is flowed through the cavity 51 provided at the bottom of the developing tank 50 to stabilize the temperature of the developing solution.

When the detected temperature reaches the specified temperature,
The shutter 55 is again opened, and the semiconductor substrate 14 is transported into the developing solution in the developing tank 50 by the transport arm 13 to develop the resist film on the semiconductor substrate. During development, the shutter 55 is closed. However, even during this transfer, the surface temperature of the substrate 14 is detected,
When the detected temperature falls below the specified temperature, the transfer is stopped until the temperature of the substrate 14 is increased by the upper constant temperature plate 10, or the substrate 14 is placed on the lower constant temperature plate 11 again, and the substrate temperature becomes the specified value. Restarts the transport from. Further, when the substrate temperature falls below the specified value during the transfer, the transfer may be stopped, and the occurrence of the abnormality may be notified by generating a warning sound or displaying a lamp.

In the above-described developing device, the upper constant temperature plate 10 with the windshield 17 moves in the state of being close to the substrate when the semiconductor substrate 14 is transported. The substrate can be transported to the developing tank 50 while keeping the temperature substantially the same as the liquid. Therefore, the semiconductor substrate 14 can be immersed in the developing solution with almost no temperature difference from the developing solution. Also,
During development, the upper constant temperature plate 10 acts as a lid of the developing tank 50 to substantially seal the developer, so that a change in temperature of the developer due to heat of vaporization of the developer can be suppressed. As a result, it becomes possible to develop a pattern with less in-plane variation on the resist film on the semiconductor substrate 14 than before.

[0029]

As described above, according to the present invention, a semiconductor this according to the invention suppress the vaporization heat generation of the developer can develop the high accuracy of the pattern further suppress the substrate temperature change during the substrate transfer
A method for developing a substrate can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view of a pair of upper and lower constant temperature plates and a transfer arm according to an embodiment of the present invention.

FIG. 2 is a plan view of an upper constant temperature plate and a transfer arm according to one embodiment of the present invention.

FIG. 3 is a cross-sectional view of a developing device according to one embodiment of the present invention.

FIG. 4 is a cross-sectional view and a plan view of a conventional transfer arm and a constant temperature plate.

FIG. 5 is a sectional view of a conventional developing device.

FIG. 6 is a characteristic diagram showing a temperature rise of a semiconductor substrate by a conventional constant temperature plate.

FIG. 7 is a plan view showing an in-plane variation of a pattern line width by a conventional developing method.

FIG. 8 is a diagram showing the relationship between the time when a semiconductor substrate is placed on a conventional constant temperature plate and the in-plane variation of the pattern line width.

[Explanation of symbols]

10 ... upper constant temperature plate, 11 ... lower constant temperature plate, 12 ... heating wire, 13 ... transfer arm, 14 ... semiconductor substrate, 16 ... nail, 17 ...
Windshield, 18 ... temperature sensor.

Claims (4)

(57) [Claims] A step of setting a semiconductor substrate on which a film to be developed is formed to a desired temperature; and a step of bringing the substrate close to a constant-temperature plate having the desired temperature set into a developing tank containing a developing solution. Transporting the semiconductor substrate. 2. A developing method of a semiconductor substrate according to claim 1, characterized by comprising further the step of the lid to the developing tank. 3. The substrate surface temperature is monitored in a non-contact manner. If the substrate surface temperature is out of a specified range during the transfer of the substrate, the substrate is immersed in a developing solution until the surface temperature is in a specified range. The method for developing a semiconductor substrate according to claim 1 , wherein there is no development. 4. A monitor in a non-contact the substrate surface temperature, when the substrate surface temperature during substrate transfer is out of the range of prescribed values, a semiconductor according to claim 1, characterized in that to stop the development Substrate development method.