JP2613183B2 - Resist film forming equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist film forming apparatus for forming a resist film by coating a resist film on a wafer. The present invention relates to a resist film forming apparatus that can carry out the discrimination with distinction.

[0002]

2. Description of the Related Art FIG. 5 is a view showing a coating portion of a conventional resist coating apparatus. In the figure, (1) is a wafer, (2) is a vacuum chuck for fixing the wafer by a decompression method, (3) is a resist film, and (4) is a nozzle for discharging the resist.

[0003] The resist coating apparatus configured as above is
When the resist is discharged from the nozzle (4) onto the wafer (1),
When the motor (not shown) rotates at the set number of revolutions, the wafer (1) rotates together with the vacuum chuck (2) in the direction indicated by the arrow in the figure, for example, and the centrifugal force causes the wafer (1) to be uniformly placed on the wafer (1). A resist film (3) is formed. Next, the wafer (1) is heated by a pre-bake device, and the resist film (3) is heated.
The organic solvent contained therein is evaporated. Thereafter, the wafer (1) on which the resist film (3) has been formed enters an exposure step.

[0004]

FIG. 6 shows the relationship between the resist film thickness, the reflectance, and the pattern size. The Figure, the resist film thickness (T _R) and the surface reflectance (ref), there is a periodicity between the pattern dimension. According to this, in order to obtain a pattern dimension (CD) with good reproducibility, the pattern dimension (C
D) a method of coating is taken as a target less resist thickness of (T _R) change. For example, A at which the pattern dimension (CD) variation is smaller than around the point B where the pattern dimension (CD) variation due to the change of the resist film thickness (T _R ) is large.
The pattern size (CD) can be controlled more accurately by applying the resist film thickness (T _R ) near the point or the point C as a target.

Incidentally, the conventional resist coating apparatus operates ignoring subtle changes in the temperature of the wafer itself, the temperature of the environment, the viscosity of the resist, and the like during wafer processing. small resist film thickness (T _R)
Coating conditions out changes while processing be set initial conditions with the goal, the resist film thickness between wafers (T _R)
And the fluctuation of the resist pattern dimension (CD) becomes large.

[0006] Even if the thickness of the resist applied by the resist coating apparatus varies, the resist film is prebaked regardless of the state of the thickness of the resist film, and then the process proceeds to an exposure step. The resist film is exposed based on a predetermined pattern and then developed. Inspect whether the resist pattern of the developed resist film is formed properly, and if it is not formed properly, it is regarded as defective, and the resist film on which the resist pattern of the defective wafer is formed is removed. The wafer that has been removed and from which the resist film has been removed again is sent to a resist coating apparatus and processed as a reclaimed wafer.

However, as is apparent from FIG. 6, if the film thickness of the resist film changes, the resist size (CD) also changes accordingly, so that the film thickness of the resist film becomes the target resist size (CD). If the film thickness of the resist film deviates from the appropriate value, the resist dimension (CD) formed through exposure and development also deviates from the target resist dimension (CD). It was a defective product, and while performing unnecessary exposure and development,
It took a lot of time before it could be used as a recycled wafer.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and it is possible to eliminate unnecessary exposure and development of a resist film after a resist film is formed on a wafer, and to regenerate a wafer by a defective resist film. It is an object of the present invention to obtain a resist forming apparatus that can use the compound at an early stage.

[0009]

According to the present invention, there is provided a resist forming apparatus for applying a resist film on a wafer, and a pre-baking apparatus for pre-baking the resist film applied on the wafer by the resist applying apparatus. And a film thickness judging means for detecting the film thickness of the resist film on the wafer prebaked by the prebaking device, and outputting a film thickness appropriateness signal indicating whether or not the film thickness of the resist film is an appropriate value. A resist coating film thickness control means connected to the film thickness determining means for controlling the coating film thickness of the resist film, and a film thickness appropriate signal from the film thickness determining means, and the film thickness appropriate signal is an appropriate value. This means that a non-defective product is defined as a non-defective product, and a non-defective product is provided with a wafer unloading means for unloading a wafer having a resist film pre-baked as a non-defective product. It is.

[0010]

According to the present invention, the film thickness judging means and the wafer unloading means detect the thickness of the resist film on the prebaked wafer, and unload the wafer into good and defective products based on the thickness.

[0011]

【Example】

Embodiment 1 FIG. FIG. 2 is a main part configuration diagram showing a resist forming apparatus according to one embodiment of the present invention. In the figure, (1) is a wafer, (3) is a resist film, (5) is a stage on which a wafer (1) is placed after resist coating by a resist coating device and pre-baked by a pre-baking device, and (6) is a reflectance measurement. (7) is the incident light from the light source (6) to the resist film (3) on the wafer (1), and (8) is the resist film on the wafer (1).
This is the reflected light from (3).

(9) is a detector for receiving the reflected light (8),
(10) is an AD converter that converts the signal from the detector (9) from analog to digital, and (11) compares the signal output from the AD converter (10) with the set value and reflects the signal from the wafer (1). It is determined whether or not the value of the ratio (resist film thickness) is appropriate. If the value is not appropriate, the reflectance determining means for calculating the optimum application rotation speed at this time and from the film thickness of the previous resist film and the coating rotation speed is used. The detector (9) and the A / D converter detect the film thickness of the resist film (3) on the wafer (1) prebaked by the prebake device, and determine whether the film thickness of the resist film (3) is appropriate. It also constitutes a film thickness judging means for outputting a film thickness appropriate signal indicating whether or not the value is a value.

(12) is a coating speed control means for resetting the coating speed obtained by the reflectance judging means (11), and (13) is a resist having a value set by the coating speed control means (12). A motor for rotating the vacuum chuck (2) shown in FIG. 1 at the time of resist coating in the coating apparatus, and (14) a reflectivity determining means (11) for determining whether the reflectivity (resist film thickness) is appropriate or not. This is a wafer unloading means that receives a film thickness aptitude signal indicating a non-defective product and a non-defective product of the wafer separately.

Here, for convenience, an angle is provided between the incident light (7) and the reflected light (8).
(7) shall be perpendicularly incident on the wafer (1).

FIG. 3 is a block diagram of the main body of the processing apparatus of the embodiment of FIG. In the figure, (17) is a microcomputer having an input circuit (18), a CPU (19), a target value (20) inputted from outside, a memory (21), and an output circuit (22). The CPU (19) realizes the function of the reflectance determining means (11) of FIG.

Next, the operation of the above embodiment will be described with reference to FIGS. Figure 4 shows a microcomputer
17 is a flowchart showing a reflectance determination program stored in a memory (21) of (17).

[0017] Between the coating rotational speed of the film thickness and the resist coating unit of a resist film is coated with a resist coating device (3), the thickness of the resist film to T _R (3) (Å), the ω if the coating speed and (rpm) relationship that T _R = pω ^q [1]. Here, p and q are constants experimentally obtained. Therefore, given two-point coordinates of two variables T _R and ω, the values of p and q at the time of coating can be obtained.

In step (25), the desired resist film (3)
When the film thickness (T _RA ) is set, the coating rotation speed of the resist coating apparatus corresponding to the film thickness is set at the same time. The coating rotation speed in this case is given by the above equation [1], and the constants p and q
It is assumed that a base value is given for the resist to be applied. Next, it is determined whether or not the application rotation speed of the resist application device set in step (26) needs to be corrected.

If it is determined that the application rotation speed needs to be corrected, the application rotation speed is changed in step (27). The value of the number of revolutions is the value determined in step (29) described later, and the resist is applied to the next wafer (1) by the resist coating device at this value, and the resist applied on the wafer (1) is used. After pre-baking the film (3) with a pre-bake device, the reflectance of the surface of the resist film (3) on the wafer (1) is measured. On the other hand, if it is determined that the coating rotation speed does not need to be corrected, a resist is applied to the next wafer (1) at the same coating rotation speed, pre-baking is performed, and the wafer is baked.
The reflectance of the surface of the resist film (3) of (1) is measured.

Next, once the surface reflectance (ref) has been measured, a reflectance signal is received in step (28). This signal is obtained by digitizing a signal detected by the detector (9) and inputting it to the input circuit (18). This signal is replaced in step (29) as the relationship between the thickness of the resist film (3) corresponding to the reflectance and the number of coating revolutions in the resist coating device.

However, in FIG. 6, when the reflectance of the first wafer is shifted from the target reflectance (point A) to the positions of points B and D, this wafer (1) is The resist film at point D has the thickness (T _RB ) of the resist film (3)
Since it is not possible to determine whether the film thickness (T _RD ) of (3) is satisfied, slightly increase the number of coating revolutions of the resist coating apparatus for the second wafer (1) (for example, 1 to the set number of coating revolutions).
Increase% rotation speed. ).

With this feedback control, the second wafer
When (1) comes to step (29), the second wafer (1)
The film thickness of the resist film (3) than the sheet of wafer (1) (T _R)
Since the surface reflectivity (ref) of the resist film (3) is increased or decreased, it is determined whether the first wafer (1) corresponds to the point B or D. together can be determined, the relationship between the thickness (T _R) and the coating rotational speed of the resist coating unit (omega) of the resist film (3) is obtained two points.

Accordingly, with respect to the third and subsequent wafers (1), the thicknesses of the two resist films (3) of the previously processed wafer (1) and the currently processed wafer (1) Two relationships are obtained between T _R ) and the number of rotations (ω) of application of the resist coating device. When two coordinates of these two variables T _R and ω are given, the values of p and q at the time of resist coating in the resist coating device can be determined from the equation [1], and the third and subsequent wafers ( The number of coating rotations of the resist coating device corresponding to the target film thickness (T _RA ) of the resist film (3) for 1) is calculated.

In step (29), when the number of application rotations of the resist coating apparatus for the next wafer (1) is calculated, it is determined in step (30) whether a lot end signal has been sent. If it is determined that there is no end signal, step (2
Return to 6). If it is determined that there is an end signal, the process ends here.

On the other hand, based on the measurement of the resist film (3) on the wafer (1) prebaked in step (26), if it is determined whether or not the coating rotation speed of the resist coating device needs to be corrected, A film thickness appropriate signal indicating whether or not the film thickness of the resist film (3) on the prebaked wafer (1) is an appropriate value is output to the wafer unloading means (14). The wafer unloading means (14) which has received the film thickness appropriateness signal determines that the received film thickness appropriateness signal is an appropriate value, as a non-defective product, and indicates that the received film thickness appropriateness signal is not an appropriate value. Pre-baked wafer (1) with mounted resist film (3)
Is shipped separately for non-defective products and defective products. The wafer (1) delivered as a non-defective product goes to the next process, the exposure process and the development process, and the wafer (1) delivered as a defective product is a resist film.
(3) is removed and sent to the resist coating device again to apply the resist.

In the above embodiment, the thickness of the resist film (3) is controlled by adjusting the number of rotations of the resist coating apparatus. However, the number of rotations of the resist coating apparatus is replaced by the pre-bake time in the pre-bake apparatus. The thickness of (3) may be controlled. In this case, (12) of FIG. 2 is a pre-bake time control means (13) is a heater, (23) of FIG. 3 is a pre-bake time setting section, and (26) of FIG. , (27) change the pre-bake time, and (29) calculate the pre-bake time.

[0027]

As described above, the present invention detects the thickness of a resist film on a wafer prebaked by a prebaking apparatus and determines whether or not the thickness of the resist film is an appropriate value. Film thickness judging means for outputting a film thickness aptitude signal indicating
The film thickness appropriateness signal is received from the film thickness determination means, and if the film thickness appropriateness signal indicates an appropriate value, it is regarded as a non-defective product. In addition, since a wafer unloading means for unloading a defective product is provided, unnecessary exposure and development of the resist film after the formation of the resist film on the wafer can be eliminated, and the utilization of the reclaimed wafer due to the defective resist film can be made earlier. It has the effect of.

[Brief description of the drawings]

FIG. 1 is a sectional view of a coating section of a resist coating apparatus in a resist forming apparatus according to an embodiment of the present invention.

FIG. 2 is a main part configuration diagram of a resist forming apparatus showing one embodiment of the present invention.

FIG. 3 is a main configuration diagram of a processing apparatus in a resist forming apparatus according to an embodiment of the present invention.

FIG. 4 is a flowchart illustrating a processing operation of the resist forming apparatus according to the embodiment of the present invention.

FIG. 5 is a sectional view of a coating section of a conventional resist coating apparatus.

[FIG. 6] The thickness of the resist film (3) applied on the wafer (1), the surface reflectance of the resist film (3), and the resist film (3)
FIG. 3 is a diagram showing a relationship with pattern sizes of FIG.

[Explanation of symbols]

1 wafer, 3 resist film, 9
Detector, 10 AD converter, 11
Reflectivity determining unit, 14 Wafer transfer means.

Claims (1)

(57) [Claims] 1. A resist coating device for coating a resist film on a wafer, a pre-baking device for pre-baking a resist film applied on the wafer by the resist coating device, a resist film on a wafer pre-baked by the pre-baking device Film thickness judging means for detecting the film thickness of the resist film and outputting a film thickness appropriateness signal indicating whether or not the film thickness of the resist film is an appropriate value. Resist coating film thickness control means for controlling the film thickness appropriateness signal from the film thickness determining means, and when the film thickness appropriateness signal means an appropriate value, it is regarded as a non-defective product, which means that it is not an appropriate value. A resist film forming apparatus, comprising: a wafer unloading means for unloading a wafer having the resist film prebaked as a defective product according to a good product or a defective product.