JP2000084468A - Method for checking discharge-quantity of resist and apparatus for resist coating - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy and the reproducibility of the thickness of a resist coated film by measuring the weight-change of a coated resist with the passage of time by using a measuring device which measures the weight of a wafer placed on a chuck continuously. SOLUTION: A discharge-quantity of a resist 8 on a wafer 9 is determined by increasing weight of a chuck 10 from the beginning of discharging to the end, namely, the increasing weight is input to a comparing-determining circuit 6 in which the difference between the increasing weight and the set weight is compared and processed, and then the discharge-quantity of the resist on the wafer 9 to be next treated are not changed when dripped quantities of the resist 8 are within 5% or less ± a standard value, and when they are above 5%, a correcting value is computed by a operating circuit 5 and a correcting value is directed to a discharge-quantity regulator 4, and an action is taken on a discharge pump 3 of the resist so that the discharge-quantity on the wafer 9 to be next treated is adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for monitoring a resist discharge amount and a resist coating apparatus, and more particularly to an apparatus for coating a semiconductor wafer with a resist or SOG.

[0002]

2. Description of the Related Art Conventionally, the amount of resist discharged is monitored by an operator using a graduated cylinder 13 to periodically measure the amount of resist dropped from a resist discharge nozzle 1 as shown in FIG. When the value deviates from the standard, the resist discharge pump 4 is adjusted. After the adjustment, the ejection amount is measured again to check whether the value is within the standard. If the standard was not met, the operation of redoing the adjustment was repeatedly performed.

[0003]

The measurement and adjustment work of the resist discharge amount in the conventional method is performed by a human and is regularly monitored, so that a coating error that causes a measurement error occurs. Between the measurement and the measurement, there is a problem that the discharge amount fluctuates and coating unevenness occurs, and that a long time is required for adjustment work.

[0004]

(1) In a method of monitoring the amount of resist discharged when applying resist, SOG, etc. to a wafer, a measuring means for constantly measuring the weight of a chuck for mounting a wafer is provided. It is characterized in that the change in weight of is measured in a timely manner.

(2) In a method of monitoring a resist discharge amount when a resist, SOG, or the like is applied to a wafer, a comparison / judgment circuit for feeding back a measured value of the chuck and comparing the measured value with a standard value is provided. It is characterized in that it has a function of automatically adjusting the resist discharge mechanism based on a signal from an arithmetic circuit for setting a correction amount when the value deviates from the value, and adjusting the resist discharge amount.

(3) Also, resist, SOG on the wafer
In the method of monitoring the resist discharge amount when applying such as,
The maximum value of the chuck weight is measured for each processed wafer, and the weight is integrated for n wafers, thereby monitoring the change over time with respect to the weight of the n wafers and calculating the inclination thereof,
It has a function of correcting a resist ejection amount correction value obtained from one wafer.

(4) A resist coating apparatus for coating resist, SOG, etc. on a wafer, having a function of adjusting the discharge time at the next discharge so that the discharge amount of resist and SOG on the wafer surface is always constant. It is characterized by.

(5) In a resist coating apparatus for applying resist, SOG, etc. to a wafer, a chuck for mounting and fixing the wafer, a cup surrounding the chuck, and the chuck are supported by weight measuring means for measuring the weight thereof. It has a function.

(6) In a resist coating apparatus for coating resist, SOG, etc. on a wafer, a measuring means for constantly measuring the weight of a chuck for mounting a wafer is provided, and a function for measuring a change in weight during resist coating in a timely manner. It is characterized by having.

(7) The resist coating apparatus according to the present invention has an arithmetic circuit for setting a correction amount when a change in weight of the chuck on which the wafer is placed deviates from the standard value. It has a function of automatically adjusting the resist discharge mechanism and adjusting the resist discharge amount.

[0011]

According to the present invention, the discharge weight of the resist is monitored,
By controlling, the discharge amount of the resist onto the semiconductor wafer can be always kept constant. In addition, since the monitoring is constantly performed, the variation in the resist film thickness between lots is reduced, and the dimensional accuracy can be significantly improved.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. FIG. 1 is a schematic diagram for explaining an embodiment of the present invention.

In FIG. 1, a wafer 9 has a chuck 10
Is mounted and fixed. A predetermined amount of resist is discharged from the resist discharge nozzle 1 to the center of the wafer 2 to form a resist 8. FIG. 4 is a diagram showing the measured time change of the chuck weight at that time, in which the horizontal axis represents the resist discharge time (from the start to the end of discharge) and the vertical axis represents the chuck weight. FIG. 2A shows a line L indicating a temporal increase in chuck weight when the resist is normally discharged onto the wafer 2. The resist discharge amount of the resist 8 discharged onto the wafer 9 is obtained by the weight increase A of the chuck 10 from the start to the end of resist discharge. FIG.
(B) shows the lines M and N of the increase in the chuck weight with time when the amount of the resist 8 is abnormal. The line M is located above the line L, and this is the case where the resist discharge amount is large. Also, the line N is located below the line L, and this is the case where the resist discharge amount is small.

The increase A is input to the comparison judgment circuit 6. The comparison determination circuit 6 compares and calculates how much the increase A is different from a set value (standard value). If the calculated resist drop amount 8 on the wafer is within 5% of the standard, the resist discharge amount on the next wafer to be processed is the same. If the drop amount exceeds 5% of the standard value, the arithmetic circuit 5 calculates a correction amount and instructs the discharge amount adjusting mechanism 4 to the correction amount to operate the resist discharge pump 3. Then, the discharge amount of the next wafer is adjusted.

Next, FIG. 3 shows a change with time of the chuck weight 10 when the increase A is added for n sheets. n
The increase line when the resist discharge amount is normal up to the first sheet is denoted by Q, the line where the change in weight with time decreases as the number of processed sheets increases, and the line where the change over time increases becomes R. In the case of the line S, the resist discharge amount (the resist 8) per wafer gradually decreases as the number of processed wafers increases. In the case of the line R, the wafer This shows that the resist ejection amount per wafer (the resist 8) increases as the number of processed wafers increases.

By adding the temporal change of the chuck weight up to the number n of processed wafers, a long-term temporal change of the resist discharge amount can be captured. As a result, an averaging effect appears, and a gradient for which the amount of variation is predicted is incorporated into the correction amount calculated from the comparison determination circuit 6 and the arithmetic circuit 5 calculated from FIG. The drive amount can be calculated. In other words,
The change rate of the resist discharge amount can be read in advance, the accuracy of feedback to the discharge amount adjusting mechanism 4 and the discharge pump 3 is improved, and the resist discharge amount can be kept more constant. When there are fluctuation factors that cannot be completely corrected by the correction on a wafer-by-wafer basis, by combining the above-described embodiments, the effect of the external fluctuation factor on the change in the resist discharge amount can be further reduced. Although made by the inventor and described based on the embodiment,
The present invention is not limited to the above embodiment. Resist, S
Various modifications can be made without departing from the scope of the present invention, such as application to chemicals other than OG and change of the method of integrating the chuck weight.

[0017]

As described above, according to the present invention, the accuracy and reproducibility of the resist coating film thickness can be greatly improved by automatically keeping the resist discharge amount constant at all times. The application device can be easily and accurately managed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a resist coating apparatus showing an embodiment of the present invention.

FIGS. 2A and 2B are diagrams showing a change over time of the weight of the chuck, wherein FIG. 2A shows a case where the weight has been increased normally, and FIG.

FIG. 3 is a diagram when the change over time of the weight of the chuck is integrated for a plurality of wafers.

FIG. 4 is a configuration diagram of a resist coating apparatus showing a conventional embodiment.

[Explanation of symbols]

Reference Signs List 1 resist discharge nozzle 2 suck back nozzle 3 resist discharge pump 4 resist discharge amount adjustment motor 5 arithmetic circuit 6 comparison and judgment circuit 7 load cell 8 resist 9 wafer 10 chuck 11 cup 12 filter 13 graduated cylinder L chuck characteristic line showing change with time of weight M Characteristic line when the change with time of chuck weight is abnormal N Characteristic line when the change with time of chuck weight is abnormal Q Characteristic line when the change with time of chuck weight is integrated for n wafers A Increase in chuck weight from resist discharge to completion Quantity n Total number of wafers

Claims (11)

[Claims] In a step of applying resist, SOG, etc. to a wafer, a measuring means for constantly measuring the weight of a chuck for mounting the wafer is provided, and a change in weight during resist application is measured in a timely manner. Resist discharge amount monitoring method. 2. A method according to claim 1, further comprising a comparison / judgment circuit for feeding back a measured value of the chuck and comparing the measured value with a standard value in a step of applying a resist, SOG or the like to the wafer. . 3. The apparatus according to claim 1, further comprising an arithmetic circuit for setting a correction amount when a change in weight of a chuck for mounting the wafer deviates from a standard value in a step of applying resist, SOG, or the like to the wafer. The method for monitoring a resist discharge amount described in the above. 4. The method according to claim 1, wherein in the step of applying resist, SOG, or the like to the wafer, a function of automatically adjusting a resist discharge mechanism based on a signal from the arithmetic circuit and adjusting a resist discharge amount is provided. 4. A method for monitoring a resist discharge amount according to claim 2 or 3. 5. In the step of applying resist, SOG, etc. to a wafer, the maximum value of the chuck weight is measured for each processing wafer, and the weight is integrated for n wafers, whereby the change over time with respect to the n wafers is obtained. And a function of calculating the inclination thereof, and correcting the resist ejection amount correction value obtained from one wafer.
The method for monitoring the resist discharge amount described in 1. 6. A process for adjusting a resist discharge amount at the next discharge so that a resist or SOG discharge amount on a wafer surface is always constant in a step of applying a resist or SOG to a wafer. Resist coating device. 7. A resist coating apparatus comprising a chuck for mounting and fixing a wafer and a cup surrounding the chuck, wherein the chuck has a function of being supported by weight measuring means for measuring its weight. 8. A resist coating apparatus, comprising: an arithmetic circuit for setting a correction amount when a change in weight of a chuck for mounting a wafer deviates from a standard value in a step of applying resist, SOG, or the like to a wafer. . 9. In the step of applying resist, SOG, etc. on a wafer, a measuring means for constantly measuring the weight of a chuck for mounting the wafer is provided, and a function of measuring the weight change during resist application in a timely manner is provided. The resist coating apparatus according to claim 6, wherein: 10. In the step of applying resist, SOG, etc. on a wafer, the maximum value of the chuck weight is measured for each processing wafer, and the weight is integrated for n wafers, whereby the change over time with respect to the n wafers is obtained. 7. The resist coating apparatus according to claim 6, further comprising a function of monitoring the inclination, calculating a slope thereof, and correcting a resist discharge amount correction value obtained from one wafer. 11. A resist coating apparatus having a function of automatically adjusting a resist discharge mechanism in accordance with a signal from said arithmetic circuit in a step of applying a resist, SOG, or the like to a wafer, thereby adjusting a resist discharge amount.