JPH11238676A - Resist developing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for developing resist by which resist patterns which a high degree of uniformity in size can be formed. SOLUTION: In this method for developing resist, a semiconductor wafer 1 is rotated by a spin chuck 5. A developer liquid 4 is discharged from a developing liquid discharging nozzle 3 onto a resist 2 formed on the surface of the semiconductor wafer 1 and is spread towards the perimeter of the semiconductor wafer 1. Then the semiconductor wafer 1 is rotated only for a rotating time t1 at a number of revolutions ω. In this case, the rotating time T1 is set smaller than the time in which the center part of the semiconductor wafer 1 is exposed. Then the rotation of the semiconductor wafer 1 is stopped, and the stop is continued for a stop time t2 to make the distribution of the developer liquid 4 in equilibrium state. The stop time t2 is set larger than the time in which the distribution of the developing liquid 4 is returned to the equilibrium state from the stopping. After that, the cycle of rotation and stopping is repeated for specified number of times.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for developing a resist used in manufacturing a semiconductor device and the like.

[0002]

2. Description of the Related Art A conventional resist developing method will be described with reference to the drawings. FIGS. 5A to 5D are process flow charts showing the most standard still development method among conventional development methods. First, as shown in FIG. 5A, a developing solution 4 is discharged from a developing solution discharging nozzle 3 onto a resist 2 formed in a film shape on a surface of a processing target made of a semiconductor wafer 1 or the like. In this case, the semiconductor wafer 1
Is sucked and rotated by the spin chuck 5. Thereby, in the semiconductor wafer 1, the developing solution 4 supplied onto the resist 2 is spread in the peripheral direction. Next, as shown in FIG. 5B, the rotation is stopped, the developer 4 is held on the resist 2 by the surface tension, and the state is kept still for 60 seconds in this state. As a result, the development reaction of the resist 2 by the developer 4 proceeds. Next, as shown in FIG.
The pure water 7 is discharged by the pure water discharge nozzle 6 while rotating the semiconductor wafer 1. The discharged pure water 7
Cleans the semiconductor wafer 1 by washing away the developer 4. Finally, as shown in FIG. 5D, the resist 2 formed on the surface of the semiconductor wafer 1 is dried by rotating the semiconductor wafer 1 to shake off the pure water 7.

FIGS. 6A to 6C are process flow charts showing a rotary developing method among the conventional developing methods. The same components as those in FIG. 5 are denoted by the same reference numerals. First, FIG.
As shown in FIGS. 5 (a) and 5 (b), as in FIGS. 5 (a) and 5 (b), the developer 4 is supplied onto the resist 2 while rotating the semiconductor wafer 1 and spread in the peripheral direction. The developing reaction of the resist 2 by the developing solution 4 proceeds. Next, as shown in FIG. 6C, the development reaction is allowed to proceed for 60 seconds while rotating the semiconductor wafer 1 at a low rotation speed at which the developer 4 does not scatter, for example, at 20 rpm.
Hereinafter, similarly to FIGS. 5C and 5D, cleaning with pure water and drying by rotation are sequentially performed.

[0004]

However, according to the above-mentioned conventional developing method, there is a problem that the uniformity of pattern dimensions is deteriorated in a resist pattern formed by development. FIGS. 7A and 7B are diagrams showing the relationship between the pattern width of the resist pattern formed by the conventional still development method and the conventional rotation development method, and the relative position along the diameter of the semiconductor wafer. FIG. 7A shows a conventional static development method with a development time of 60 seconds, and FIG.
The width of the pattern formed when each of the conventional rotation developing methods is performed by continuous rotation at 0 rpm for 60 seconds is shown. The variation of the pattern width at this time is 3σ
Were 0.047 μm and 0.042 μm.

[0005] According to the conventional static developing method shown in FIG. 5, the semiconductor wafer 1 is stopped and the developing reaction proceeds. Therefore, the developer 4 on the semiconductor wafer 1
7A is liable to be affected by the temperature distribution, the concentration distribution, the concentration distribution of the reaction product, and the like, and the pattern width becomes narrow at the peripheral portion of the semiconductor wafer 1 as shown in FIG. According to the conventional rotary developing method shown in FIG. 6, the developer 4 flows sufficiently only mainly at the start and stop of the rotation. The developer 4 cannot be sufficiently stirred. Therefore, the effects of the temperature distribution and the concentration distribution of the developing solution 4 on the semiconductor wafer 1 and the concentration distribution of the reaction product cannot be reduced, and the effect of making the pattern width uniform cannot be obtained.
Further, since the semiconductor wafer 1 is rotated at a relatively low rotation speed so that the developer 4 is not scattered, a vortex is generated in the developer 4 along the rotation direction. By this vortex, FIG.
As shown in (b), there is a problem that the pattern width at the central portion of the semiconductor wafer 1 is reduced, and conversely, the uniformity of the pattern dimensions is deteriorated.

The present invention has been made in consideration of the above-described conventional problems, and has as its object to provide a method for developing a resist for forming a resist pattern having excellent uniformity of pattern dimensions.

[0007]

In order to achieve the above object, the present invention provides a first step of supplying a developing solution to the surface of an object to be processed, a second step of causing a developing reaction to proceed, A method for developing a resist comprising a third step of washing away the developing solution on the surface and a fourth step of drying the surface, wherein the developing solution is agitated while the developing reaction is in progress. It is.

Specifically, the solution of the first aspect of the present invention is to provide a method of developing a resist, wherein the second step includes a step of applying a periodic rotation consisting of rotation and stop to the object to be processed. It was done.

According to this configuration, while the development reaction is in progress, the developer is caused to flow by rotation and stop. Therefore, the developer can be sufficiently stirred.

A second aspect of the present invention provides a method of developing a resist, wherein the second step comprises rotating one cycle of the periodic rotation at a predetermined number of rotations for a rotation time t1. And a stop that is executed for a stop time t2 thereafter, and has a step of repeating the periodic rotation.

According to this configuration, while the development reaction is in progress, the developer is caused to flow repeatedly so as to reciprocate between the central portion and the peripheral portion of the object by repeatedly rotating and stopping. Therefore, the developer can be sufficiently stirred.

[0012] Specifically, a solution developed by the invention according to claim 3 is a method of developing a resist, and the second step is to periodically rotate the resist in accordance with a change in wettability of the surface of the processing object with a developing solution. And a step of changing at least one of the number of rotations, the rotation time t1, and the stop time t2 in each cycle.

According to this configuration, an optimum condition can be selected according to a change in wettability of the surface of the processing object with the developing solution.

In a second aspect of the present invention, there is provided a method of developing a resist. The second step comprises rotating the resist from the start of rotation until the surface is exposed at the central portion of the workpiece by centrifugal force. The configuration includes a step of setting the rotation time t1 such that t1 <t0 with respect to the continuation time t0.

According to this configuration, a large number of rotations at which the developer is scattered when the continuous rotation is performed can be used during the rotation time t1 during which the surface of the object is not exposed. Therefore, the effect of stirring the developer can be enhanced.

In a second aspect of the present invention, there is provided a method for developing a resist. The second step comprises a step of stopping the rotation and stopping the distribution of the developing solution on the surface of the object to return to an equilibrium state. The stop time t2 is set to t2 with respect to the stabilization time t3.
> T3.

According to this configuration, the resist can be developed under a stable developer distribution.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for developing a resist according to a first embodiment of the present invention will be described with reference to the drawings. FIGS. 1A to 1D are process flow charts showing a method for developing a resist according to the first embodiment. First, FIG.
As shown in (1), a developing solution 4 is discharged from a developing solution discharge nozzle 3 onto a resist 2 formed in a film shape on the surface of an object to be processed including a semiconductor wafer 1 and the like. In this case, the semiconductor wafer 1 is sucked and rotated by the spin chuck 5. As a result, in the semiconductor wafer 1, the developer 4 supplied on the resist 2
Are spread in the peripheral direction. Next, as shown in FIG. 1B, the rotation is stopped and the developer 4 is held on the resist 2 by surface tension.

Next, as shown in FIG. 1C, the semiconductor wafer 1 is rotated by the spin chuck 5 at a rotation speed ω (rpm).
Rotate with. In the present embodiment, ω is set to 50 rpm
And Due to the centrifugal force, the developer 4 starts to move to the periphery of the semiconductor wafer 1. If the rotation is continued as it is, the developer 4 scatters, or the developer 4 disappears at the center of the semiconductor wafer 1 and the surface of the semiconductor wafer 1 is exposed. In this case, the rotation time t1 (second) for rotating the semiconductor wafer 1 with respect to the rotation duration t0 from the start of rotation of the semiconductor wafer 1 to the occurrence of surface exposure at the center is t1 < It is necessary to set so as to satisfy the condition of t0. In the present embodiment, since t0 was 1.2 seconds, t1 was set to 0.5 seconds.

Next, as shown in FIG. 1D, the rotation of the spin chuck 5 is stopped to stop the semiconductor wafer 1, and
Further, the state is continued for the stop time t2 (second). By stopping the rotation, the developer 4 that has moved to the peripheral portion of the semiconductor wafer 1 moves to the center again, and the developer 4 returns to the distribution in the equilibrium state. In this case, the reproducibility and stability of development can be improved by setting the stop time t2 longer than the time from when the rotation is stopped until the developer 4 returns to the distribution in the equilibrium state, that is, the stabilization time t3 (second). It turned out to be better. In this embodiment, since t3 was 2.0 seconds, t2 was set to 3.5 seconds.

Next, this cycle is repeated during the development time, with the rotation of the rotation time t1 and the stop of the stop time t2 shown in FIGS. 1 (c) and 1 (d) as one cycle. As a result, the development reaction of the resist 2 by the developer 4 proceeds. In the present embodiment, the development time is 60 seconds, t1 = 0.5 seconds, and t2 = 3.5 seconds, and one cycle (= 4 seconds) is repeated, and the cycle is repeated 15 times. Hereinafter, similarly to FIGS. 5C and 5D, cleaning with pure water and drying by rotation are sequentially performed.

FIG. 2 is a development sequence diagram showing the relationship between time and rotation speed in the process flow of this embodiment.
In FIG. 2, a developing reaction that is a repetition of a cycle including a rotation of a developing solution discharge with rotation, a rotation of a rotation time t1 at a rotation speed ω, and a stop of a stop time t2,
The respective steps of drying with rotation are sequentially executed.

The flow of the developing solution 4 between the peripheral portion and the central portion of the semiconductor wafer 1 is caused by rotation and stoppage, that is, a change in centrifugal force due to a change in rotation speed. In order to obtain, it is necessary to change the centrifugal force effectively. Further, in the semiconductor wafer 1, the optimum stirring conditions vary depending on the surface condition such as the type of resist and the presence or absence of an antireflection film on the resist. Regardless of the surface condition, an optimum stirring state can be realized by controlling the number of rotations ω, the rotation time t1, and the stop time t2 in development to effectively change the centrifugal force.

The results obtained by using the resist developing method according to this embodiment will be described below. As a semiconductor wafer, Si
A wafer was used. An i-line photoresist was applied to the surface of the Si wafer, and a pattern having a width of 0.4 μm was exposed using an i-line exposure apparatus, and developed by the developing method according to the present embodiment. The pattern width of the formed resist pattern was measured at 20 locations along the diameter of the wafer using a length measurement SEM. FIGS. 3A and 3B are diagrams showing the relationship between the pattern width of the resist pattern formed by the developing method according to the present embodiment and the relative position on the semiconductor wafer. The variation in the pattern width at this time was 0.012 μm in 3σ. Fig. 7 each
Compared with the variation of the pattern width between the conventional static development method and the rotation development method shown in FIGS. 3A and 3B being 0.047 μm and 0.042 μm at 3σ, respectively, It can be seen that the uniformity of the pattern width has been significantly improved.

As described above, according to this embodiment, the developer 4 is applied to the semiconductor wafer 1 a predetermined number of times.
Is made to flow back and forth between the central portion and the peripheral edge portion. As a result, the developer 4 is sufficiently agitated.
The influence of the temperature distribution, concentration distribution, concentration distribution of the reaction product, etc. can be reduced. Therefore, the resist 2 formed in a film shape on the surface of the semiconductor wafer 1 can be uniformly developed.

In the above description, 1
One cycle of the periodic rotation was configured using the kinds of rotation speed ω, the rotation time t1, and the stop time t2. Not limited to this,
One cycle may be configured by combining different conditions for each of the rotation speed, the rotation time, and the stop time. In addition, although the periodic rotation is applied to the semiconductor wafer a plurality of times, it goes without saying that it may be applied only once.

A method for developing a resist according to a second embodiment of the present invention will be described with reference to the drawings. This embodiment differs from the method for developing a resist according to the first embodiment in a step of advancing the development reaction of the resist 2 by the developer 4 by rotation and stop, that is, in FIG. The configuration is such that development is performed depending on conditions.

FIGS. 4A and 4B are development sequence diagrams each showing an example of the relationship between time and rotation speed in the present embodiment. In the development reaction shown in FIG. 4 (a), the rotation period is ω1, ω2, ω3, ω4, with a cycle consisting of the rotation of the rotation time t1 and the stop of the stop time t2.
.., Ωn−1, ωn are sequentially increased. As the development reaction progresses, the surface of the resist changes from hydrophobic to hydrophilic, and the wettability with the developing solution is improved. Therefore, the optimum rotation speed increases with time. As shown in FIG. 4A, the uniformity can be further improved by setting the number of rotations to an optimum value for the surface state of the resist in each cycle.

In this embodiment, the number of revolutions is changed in three stages. During the progress of the development reaction, first 5 times at 50 rpm, then 5 times at 70 rpm, then 90 rpm
After 5 rotations at pm, a total of 15 rotations were performed. The cycle was fixed at 4 seconds, the rotation time t1 was set to 0.5 seconds, and the stop time t2 was set to 3.5 seconds. The variation of the pattern width at this time was 0.010 μm in 3σ. Therefore, according to the present embodiment, the uniformity of the pattern width equal to or larger than the value of the first embodiment can be obtained.

Further, as shown in FIG. 4B, in the development reaction, the rotation time and the stop time may be respectively changed while keeping the rotation speed ω constant. Also in this case, the development reaction can proceed under the optimum conditions in each cycle in accordance with the change in the wettability of the resist surface with the developer.

In the description of this embodiment, the number of rotations or the rotation time and the stop time are changed in each cycle in accordance with the change in the wettability of the resist surface with the developing solution. . However, the present invention is not limited thereto, and one of the number of rotations, the rotation time, and the stop time, or an appropriate combination thereof may be changed.

[0032]

According to the present invention, the developing solution is sufficiently stirred during the progress of the developing reaction, so that the effects of the temperature distribution, the concentration distribution of the developing solution, the concentration distribution of the reaction product, and the like are reduced. Can be reduced. Therefore, the resist formed in a film shape on the surface of the semiconductor wafer can be uniformly developed, so that it is possible to provide a resist developing method for forming a resist pattern having excellent pattern dimension uniformity.

[Brief description of the drawings]

FIGS. 1A to 1D are process flow charts showing a method for developing a resist according to a first embodiment of the present invention.

FIG. 2 is a development sequence diagram showing a relationship between time and rotation speed in the development method of FIG.

FIGS. 3A and 3B are diagrams each showing a relationship between a pattern width formed by the developing method of FIG. 1 and a relative position on a semiconductor wafer;

FIGS. 4A and 4B are development sequence diagrams each showing an example of a relationship between time and rotation speed in a resist developing method according to a second embodiment of the present invention.

FIGS. 5A to 5D are process flow charts showing a conventional still development method.

FIGS. 6A to 6C are process flow charts showing a conventional rotational developing method.

FIGS. 7A and 7B are diagrams showing a relationship between a pattern width formed by a conventional still development method and a conventional rotary development method and a relative position of a semiconductor wafer, respectively.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 semiconductor wafer (object to be processed) 2 resist 3 developer discharge nozzle 4 developer 5 spin chuck 6 pure water discharge nozzle 7 pure water

Claims (5)

[Claims] A first step of supplying a developing solution to the surface of the object while rotating the object; and a step of stopping the supply of the developing solution to stop the supply of the developing solution on the surface of the object. A second step of advancing the development reaction of the resist, a third step of washing away the developing solution using pure water, and a fourth step of drying the surface of the object by rotating the object. And a step of sequentially applying a periodic rotation consisting of rotation and stop to the object to be processed. 2. The resist developing method according to claim 1, wherein in the second step, one cycle of the periodic rotation is performed at a predetermined number of rotations for a rotation time t1, and then stopped. And a stop that is performed for a time t2, and further comprising a step of repeating the cycle. 3. The method for developing a resist according to claim 1, wherein the second step is performed in accordance with a change in wettability of the surface of the processing object with the developing solution. Number of rotations, rotation time t1, or stop time t in the cycle
2. A method for developing a resist, comprising a step of changing at least one of the two. 4. The method for developing a resist according to claim 2, wherein in the second step, the rotation of the processing object is started at the rotation speed, and then the central portion of the processing object is centrifugally applied. A method for developing a resist, comprising: setting a rotation time t1 such that t1 <t0 with respect to a rotation continuation time t0 until the surface is exposed. 5. The resist developing method according to claim 2, wherein in the second step, the object is stopped after rotating the object at the rotation speed for the rotation time t1. With respect to the stabilization time t3 until the distribution of the developer on the body surface returns to the equilibrium state, the stop time t2 is set to t2>
A method for developing a resist, comprising a step of setting t3.