JPH0452288A - Etching device - Google Patents

Abstract

PURPOSE:To keep the plasma density between electrodes constant and to uniformly etch a film by detecting the distance between the opposed electrodes, comparing the distance with the command and moving at least one of the electrodes to correct the distance. CONSTITUTION:The distance between the opposed electrodes 4 and 5 in an etching chamber 1 is detected by the means 11 and 12, the detected data and the command are compared by an electrode correction amt. setting means 13 to set the correction amt. for the distance between the electrodes 4 and 5. At least one of the electrodes 4 and 5 is moved by the correction amt. with electrode moving means 6 and 7 to change the distance. Accordingly, the distance between the electrodes is kept constant, and a film is precisely etched without changing the density of plasma produced between the electrodes.

Description

[Detailed Description of the Invention] [Summary] Regarding an etching device equipped with parallel electrodes, the purpose of the invention is to perform uniform etching by keeping the plasma density between the electrodes constant. distance detection means for detecting the distance between two electrodes; electrode correction amount setting means for setting a correction amount for the distance between the electrodes by comparing detection data of the distance detection means with a target value; and electrode moving means for changing the inter-electrode distance by moving at least one of the electrodes by the correction amount output from the amount setting means.

[Industrial application field]

The present invention is an etching device! More specifically, the present invention relates to an etching apparatus equipped with a pair of parallel plate electrodes.

[Conventional technology]

A dry etching apparatus used for patterning or removing a film formed on a substrate, for example, as shown in FIG. It has a supporting electrode d provided within the chamber, a counter electrode e facing the supporting electrode d, and a high frequency source RF connected to the counter electrode e. The plasma is generated between the electrodes d and etches the film on the surface of the semiconductor substrate W placed on the support electrode d.

In addition, a matching device g is installed in the power transmission path from the high frequency power source RF to the counter electrode e, and this matching device g changes its self-impedance in response to load fluctuations.
The structure is such that the high frequency voltage applied between the two electrodes d and e is kept constant to maintain a uniform etching rate and etching distribution.

Incidentally, in such an apparatus, the distance between the supporting electrode d and the counter electrode tljie is narrowed, for example, to Low, thereby increasing the density of the plasma generated therebetween and increasing the etching rate.

[Problem to be solved by the invention]

By the way, the counter electrode e may be worn out due to the impact of activated ions.

For example, if a counter electrode e made of carbon is used and an etching gas of CP, CHF, etc. is used to etch the item 5io211I, the counter electrode e after being used for about 80 hours will be etched.
Since the bottom surface of the electrode is removed by several inches, the two electrodes e and
It has been confirmed that as the distance between the two surfaces increases, the plasma density decreases and the etching rate decreases.

By the way, the matching box g adjusts the electrodes d and e in response to load fluctuations.
It operates so that the voltage between the electrodes e,
It cannot cope with changes in plasma density due to the spread of f.

Therefore, even though the high frequency voltage applied between the two electrodes d and e is constant, a problem arises in that the plasma density changes due to variations in the distance between the electrodes, resulting in a decrease in etching accuracy.

The present invention has been made in view of these problems, and an object of the present invention is to provide an etching apparatus that can perform uniform etching by keeping the plasma density between the electrodes constant.

[Means to solve the problem]

The above-mentioned problem can be solved by two electrodes 4.5 disposed facing each other in the etching chamber 1, as illustrated in FIG.
Distance detection means II, 12.21.2 for detecting the distance between
2, an electrode correction amount setting means I3.23 for setting a correction amount for the distance between the electrodes 4.5 by comparing the detection data of the distance detection means with a target value, and the correction amount setting means 13.23.
The correction amount of the electrode 4.5 is adjusted by the amount of correction output from the
An etching apparatus characterized in that it is equipped with an electrode moving means 6.7 for moving one of the electrodes to change the distance between the electrodes, or the first and second electrodes 4 disposed facing each other in the etching chamber 1. .5, a high frequency power supply 8 connected to at least one of the first electrode 4 and the second electrode 5, and detecting the voltage value of the reflected wave of the first electrode 4 or the second electrode 5. The reflected wave voltage value detecting means 11.21 compares the reflected wave voltage value with respect to the inter-electrode distance investigated in advance and the voltage value of the reflected wave to determine the distance between the first and second 1t8i. detection means I2.22 and said first electrode 4 based on the detection data of said distance detection means I2.22.
or electrode correction amount setting means 13.23 for setting the correction amount of the second electrode 5; and electrode correction amount setting means 13.2.
This is achieved by an etching apparatus characterized in that it is equipped with electrode moving means 6.7 for moving the first electrode 4 or the second electrode 5 by the correction amount set by No. 3.

Therefore, it is necessary to investigate the characteristics of various electrodes in advance.

Therefore, even if the electrode 4.5 is thinned by the plasma generated between the electrodes 4.5, the distance t#firjI can always be kept constant, and etching can be performed without changing the density of the plasma generated during that time. As a result, etching accuracy is improved.

[For production]

According to the present invention, when the distance between the two electrodes 4.5 is detected and the distance differs from the target value, the correction amount of the electrode 4.5 is determined and the electrode 4.5 is adjusted by that amount. The electrodes are moved so that the distance between the electrodes matches the target value.

Further, according to the second invention, the distance between the electrodes is detected by comparing the data of the distance between the electrodes with respect to the reflected wave voltage value of the electrodes investigated in advance and the actually measured reflected wave voltage value, and the distance between the electrodes is determined. I am trying to correct the gender. In this case, the voltage value of the reflection from the electrodes increases as the distance between the electrodes increases. [Example] Therefore, the details of the present invention will be explained below based on the drawings.

FIG. 1 is a configuration diagram showing an apparatus according to an embodiment of the present invention, in which reference numeral 1 denotes an etching chamber equipped with a gas inlet 2 and an exhaust port 3, and a substrate W is placed at the bottom of the etching chamber. A support electrode 4 for mounting is provided, and a counter electrode 5 facing the upper surface of the support electrode 4 is attached to the upper part of the etching chamber l so as to be movable in the vertical direction, so that the distance between the electrodes can be changed. It is configured so that it can be done.

Reference numeral 6 denotes an electrode mover attached to the upper part of the etching chamber 1. This electrode mover 6 has a support rod 7 that can move forward and backward in a direction perpendicular to the upper surface of the support electrode 4, and is capable of moving the electrode as described later. The support rod 7 is moved by an amount instructed by the controller 8 to correct the position of the counter electrode 5 attached to the tip of the support rod 7.

Reference numeral 9 denotes 1is for applying a high frequency voltage between the counter electrode 5 and the support electrode 4, and during the power transmission path from this 1ifi 9 to the counter electrode 4, there is a high frequency voltage applied based on the magnitude and phase of the voltage reflected from the counter electrode 5. A matching box 10 is installed to keep the applied voltage value constant by changing the self-impedance, and the matching box 10 is configured to perform matching in response to load fluctuations.

The above-mentioned 1i pole movement control IBB drives the electrode mover 6 to maintain a constant distance between the opposing electrode 5 and the supporting electrode 4. It has an arithmetic circuit 12 and an electrode correction amount setting circuit 13.

The reflected wave voltage value detection circuit II described above detects the voltage value of the reflected wave reflected from the counter electrode 5, and is configured to output the detected voltage value to the interelectrode distance calculation circuit 12. .

Further, the inter-electrode distance calculating circuit 12 calculates the distance between the opposing electrode 5 and the supporting electrode 4, and uses data indicating the relationship between the inter-electrode distance and the reflected wave voltage value investigated in advance and the actually measured voltage value. The distance It between the supporting electrode 4 and the counter electrode 5 is verified.
7! It is configured to find r. In this case, there is a case where the voltage of the reflected wave increases as the distance between the counter electrode 5 and the supporting electrode 4 increases, so it is necessary to investigate the relationship between the distance between the electrodes and the voltage value of the reflected wave for various types of counter electrodes 5.

This calculation by the inter-electrode distance calculation circuit 12 is performed by the matching device 10.
The configuration is such that the adjustment is performed after the adjustment is completed, or alternately with the adjustment of the matching box 10.

The above-mentioned electrode correction amount setting circuit 13 calculates the target value l of the inter-electrode distance and the calculation data of the inter-electrode distance calculation circuit 12! , and calculates the difference between the calculated data 11 and the target value 1. If it is larger, the support rod 7 of the electrode mover 6 is lowered by the difference, and the target value 10 of the inter-electrode distance is calculated data! ! If it is larger than 1, the support rJI7 is raised by the difference, so that the interelectrode path Hp and the target value E0 finally match.

In the figure, reference numeral 14 indicates a base on which the supporting electrode 4 is attached and the etching chamber I is mounted, and M indicates a film to be etched laminated on the substrate W.

Next, the operation of the above-mentioned embodiment device 0 will be explained.

A counter electrode 5 made of carbon is attached to a support rod 7 of an electrode mover 6, and the distance from the support electrode 4 is set to, for example, about 10 cm.

Then, after placing the substrate W on which the SiO□ film is formed as the film to be etched M on the supporting electrode 4, the etching chamber 1 is etched.
was installed on the base 14 to cover the electrodes 4.5, etc., and then the air inside was removed through the exhaust port 3 to a pressure of about 1.8 Torr.
Reduce the pressure to r. Also, frequency 380kHz, output 80
A high frequency voltage is applied to the counter electrode 5 from a 0W high frequency power source 9.

In this state, CF4 and CHF are supplied from the gas inlet 2.
, and Ar gas respectively 60.60.110005
CC is introduced, and these are supplied between the supporting electrode 4 and the counter electrode 5 to form plasma, and etching of the film M to be etched is started.

Also, just before starting etching, the matching device IO
The voltage between the electrodes is held at a predetermined value.

Then, when the electrode movement controller 8 is activated, the reflected wave voltage value detection circuit 11 inputs the reflected wave from the opposing electrode 5 and detects its voltage value, and the interelectrode distance calculation circuit 12 The distance 11 between the supporting electrode 4 and the counter electrode 5 is determined by comparing the voltage value of the reflected wave with previously investigated data, and this distance data is output to the electric bridge correction amount setting circuit I3.

Further, the electrode correction amount setting value circuit 13 calculates the target inter-electrode distance 10 and the actual inter-electrode distance 1. If the measured value 2I is large, the opposing electrode 5 is lowered by the difference, and the distance between the electrodes is set to the target value! .

If the target value is larger than the actual measurement value 21, the opposing electrode 5 is raised to increase the distance between the electrodes to the target value 1. shall be.

For example, immediately after replacing the counter electrode 5, in a state where the counter electrode 5 is slightly approaching the support electrode 4, the electrode correction amount setting value circuit 13 supports the counter electrode 5 so that it is separated from the support electrode 4. A signal for moving the rod 7 is output to the electrode mover 6. Furthermore, if the counter electrode 5 becomes thinner as the total etching time increases,
The support rod 7 is moved so that the counter electrode 5 approaches the support electrode 4.

In addition, when etching 5ioJIl using the counter electrode 5 made of carbon, when the distance between the electrodes was set to 10-, the thickness decreased with the passage of time, and the thickness decreased to 3 in 80 hours.
It has been confirmed that the voltage value of the reflected wave increases as the thickness becomes thinner.

In this way, the voltage applied to the counter electrode 5 is controlled by the regulator IO.
In an etching apparatus in which the distance between the opposing electrode 5 and the support electrode 4 is adjusted by the electrode mover 6 and the electrode movement controller 8,
．． The voltage applied between electrodes 4.5 and 4.5 remains constant.
The plasma density generated during the etching period also becomes constant, improving the reproducibility of etching and improving its accuracy.

By the way, in the above embodiment, the distance between the electrodes is specifically set to correct the position of the opposing iIt pole 5, but the opposing electrode 5 can be moved by comparing the reflected wave voltage V1 with the reference voltage V0. It is also possible to modify it.

That is, as shown in the second time, the opposing electrode 5 and the electrode mover 6
The electrode movement system 'aH1B provided between
It is constituted by an electrode correction amount setting circuit 23.

The reflected wave voltage value detection circuit 21 described above is configured to detect the voltage value (1) of the reflected wave reflected from the counter electrode 5.

Further, if the magnitude of the reflected wave voltage value ■1 of the opposing electrode 5 is outside the allowable range around the reference voltage value v0, the inter-electrode distance discrimination circuit 22 outputs the voltage value ■1 to the electrode correction amount setting circuit 23. On the other hand, if the output is within the allowable range, the output is stopped. The reference voltage MV0 is obtained by actually measuring the value of the voltage reflected from the counter electrode 5 in advance when the distance between the support electrode 4 and the counter electrode 5 is set to a target value of 10.

The electrode correction amount setting circuit 23 described above receives the voltage value (■) and the reference value (■) input via the inter-electrode distance determination circuit 22. This is used to instruct the electrode mover 6 on the amount of movement by comparing the magnitudes of , and the input value is the reference value ■. If it is larger than , the counter electrode 5 is moved slightly closer to the support electrode 4 by a certain amount, while the input value is set to the reference value ■.

If it is smaller than , the configuration is such that the counter electrode 5 can be moved away from the support electrode 4 by a certain amount. The amount of movement in this case is made small, for example, 0.5 m.

As a result, the operation of slightly moving the counter electrode 5 until the distance between the electrodes reaches the desired position is continuously repeated, and when the counter electrode 5 falls within the tolerance range, the movement is stopped. I will let you do it.

In the two embodiments described above, the distance between the electrodes was detected based on the magnitude of the voltage reflected from the counter electrode 5, but the distance between the electrodes was detected based on the magnitude of the voltage reflected from the counter electrode 5. It is also possible to detect the position of the opposing electrode by means such as measuring the amount of passage, and correct the distance between the electrodes based on that data.

〔Effect of the invention〕

As described above, according to the present invention, the distance between two electrodes is detected, and if the distance differs from the target value, the correction amount of the electrode is calculated and the electrode is moved by that amount, and the electrode is moved by that amount. Since the distance between the electrodes is made to match the target, even if the electrodes become thinner, the distance between the electrodes can be kept constant and etching can be performed without changing the density of the plasma generated between them.
It becomes possible to improve the reproducibility of etching.

Further, according to the second invention, the distance between the electrodes is detected by comparing the data of the inter-electrode distance with respect to the reflected wave voltage value of the electrodes investigated in advance and the actually measured reflected wave voltage value. , the distance between the electrodes can be easily measured even during etching, so you can always! The poles can be adjusted,
Etching precision can be further improved.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an apparatus according to a first embodiment of the present invention; FIG. 2 is a configuration diagram showing an apparatus according to a second embodiment of the present invention; FIG. 3 is a configuration diagram showing an example of a conventional device. (Explanation of symbols) 1... Etching chamber, 2...Gas inlet, 3...Exhaust port, 4... Support electrode, 5... counter electrode, 6... Electrode mover, 7... between supports, 8... Electrode movement controller, 9...High frequency power supply, 10... matching box, 11...Reflected wave voltage value detection circuit, 12... Inter-electrode distance calculation circuit, 13... Electrode correction amount setting circuit, 21...Reflected wave voltage value detection circuit, 22... Inter-electrode distance discrimination circuit, 23... Electrode correction amount setting circuit, Sender: Fujitsu Limited

Claims (2)

[Claims] (1) Distance detection means (11, 12, 21, 22) for detecting the distance between two electrodes (4, 5) disposed facing each other in the etching chamber (1), and the distance detection means electrode correction amount setting means (13,
23), and electrode moving means (6, 23) for changing the inter-electrode distance by moving at least one of the electrodes (4, 5) by the amount of correction output from the correction amount setting means (13, 23).
7) An etching apparatus characterized by comprising: (2) first and second electrodes (4, 5) arranged to face each other in the etching chamber (1); and at least one of the first electrode (4) and the second electrode (5). a high frequency power source (8) connected to the , and reflected wave voltage value detection means (11, 21) for detecting the voltage value of the reflected wave of the first electrode (4) or the second electrode (5); distance detecting means (12, 22) for determining the distance between the first and second electrodes by comparing the voltage value of the reflected wave with the voltage value of the reflected wave for a previously investigated distance between the electrodes; electrode correction amount setting means (13, 23) for setting the correction amount of the first electrode (4) or the second electrode (5) based on the detection data of the detection means (12, 22); The first electrode (4) or the second electrode (
5) An etching apparatus comprising electrode moving means (6, 7) for moving the electrode.