JP2003179038A - Dry etching method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit deposition of a reaction product that is generated in dry etching, and to carry out etching with high machining accuracy. <P>SOLUTION: The dry etching method includes a mounting process for mounting a material A to be etched onto the lower electrode of a vacuum treatment chamber 20a having upper and lower electrodes 21 and 23, a heating process for heating the inside of the vacuum treatment chamber and the upper and lower electrodes, and a dry etching treatment process for carrying out dry etching treatment to the material to be etched. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a dry etching method.

[0002]

2. Description of the Related Art A photolithography technique and an etching technique accompanying it are known as typical techniques for microfabrication used in the manufacturing process of semiconductor elements and the like. The latter etching is performed to remove unnecessary portions other than the portions to be left as a pattern after exposure by photolithography, or to remove unnecessary portions that are used in a certain process but are unnecessary in the subsequent process. For such etching, dry etching is often used in which etching is performed with a gas that has been turned into plasma.

A dry etching apparatus for performing such etching (hereinafter sometimes simply referred to as an apparatus) is a vacuum processing chamber for performing dry etching on a material to be etched in a state where the inside is kept in vacuum. And a preparatory chamber which is provided adjacent to the vacuum processing chamber and holds the inside of the chamber under vacuum. This is to prevent atmospheric air from flowing into the vacuum processing chamber in which etching is performed. When the air flows into the vacuum processing chamber, the reaction product generated during etching absorbs moisture in the air and solidifies, and adheres to the inner wall of the processing chamber. In addition, solidified reaction products (hereinafter also referred to as particles) are peeled off from the side wall or the ceiling wall of the vacuum processing chamber, or are wound up by the gas flow in the vacuum processing chamber, so that the surface of the material to be etched is May also adhere. When particles adhere to the surface of the material to be etched, they have the same function as the resist film, so that the portion that should otherwise be etched remains without being removed (hereinafter, this is referred to as the film residue). ). For this reason, there is a possibility that the processing accuracy of the material to be etched may be deteriorated or the product may be defective. Since complicated maintenance is required to remove the reaction products adhering to the inside of the apparatus, development of an apparatus capable of suppressing the adhesion of the reaction products has been studied.

For example, according to the apparatus disclosed in Japanese Unexamined Patent Publication No. 6-177074, means for heating the inside of the above-mentioned preliminary chamber is provided. Also, JP-A-64-42583
According to the device disclosed in the publication, a means for irradiating the surface of a semiconductor wafer with infrared light is provided. In this way, by heating the preliminary chamber and the material to be etched,
This is to suppress the adhesion of reaction products.

[0005]

However, none of the conventional apparatuses has been able to obtain a satisfactory effect in suppressing the adhesion of reaction products to the surface of the vacuum processing chamber or the material to be etched. Further, as the number of processed materials to be etched progresses, it is unavoidable that the reaction product attached to the material to be etched interferes and the etching rate decreases.

Therefore, there has been a demand for a dry etching method which can expect a further effect in suppressing the adhesion of reaction products to the surface of the vacuum processing chamber or the material to be etched.

[0007]

Therefore, according to the dry etching method of the present invention, a step of mounting a material to be etched on a lower electrode in a vacuum processing chamber having an upper electrode and a lower electrode; The method is characterized by including a heating step of heating the inside of the processing chamber, the upper electrode and the lower electrode, and a dry etching processing step of performing dry etching processing on the material to be etched.

According to this structure, it is possible to prevent the particles due to the reaction products from adhering to both the vacuum processing chamber and the material to be etched. The temperatures of the inside of the vacuum processing chamber, the upper electrode, and the lower electrode need not all be the same. Considering the vapor pressure of the reaction product by etching, etc., the temperature inside the vacuum processing chamber is set to about 80 ° C., and the temperature of the upper electrode and the lower electrode is set to about 110 ° C. .

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. Each drawing merely schematically shows the size, shape, positional relationship and the like of each component so that the invention can be understood. Numerical conditions such as materials used, processing time, and processing temperature mentioned in the following description are only suitable examples within the scope of these inventions. Therefore, these inventions are not limited to these conditions. Further, in the drawings, hatching and the like showing the cross section are omitted.

<First Embodiment> FIG. 1 is a schematic plan view of a dry etching apparatus for explaining a dry etching method according to a first embodiment of the present invention. A dry etching apparatus 10 used here is shown. The configuration of the device is shown without the top wall of the device.

According to the dry etching apparatus of the present embodiment, a vacuum is provided in which the upper electrode and the lower electrode for plasma generation are provided inside and the material to be etched is dry-etched while the inside is kept in vacuum. Processing chamber,
In a dry etching apparatus that is provided adjacent to this vacuum processing chamber and has a preliminary chamber whose inside is kept in vacuum, in order to control the temperature of the inside of the vacuum processing chamber and each of the upper electrode and the lower electrode. Is provided. Here, the device configuration is as follows. The apparatus 10 is adjacent to the atmospheric transfer robot 100, that is, the robot that is transferred to the etching apparatus from the outside and exposed to the atmosphere. Inside the apparatus 10, a first preliminary chamber 11 is provided for carrying the material to be etched into the apparatus 10 from the robot 100 and for carrying out the material from the apparatus 10 to the robot 100. Further, a second preliminary chamber 15 is provided adjacent to the first preliminary chamber 11 via a valve 13. The inside of the second preliminary chamber 15 is always maintained at a high vacuum, and has a structure that prevents atmospheric air from flowing into a vacuum processing chamber (first vacuum processing chamber 20a and second vacuum processing chamber 20b) described later. . In addition, the second preliminary chamber 15 is provided with a transfer arm 15a for transferring the material to be etched to the vacuum processing chamber. On both sides of the second preliminary chamber 15 in the direction of 90 ° with respect to the first preliminary chamber 11, the first vacuum processing chamber 20a via the valve 17a and the second vacuum processing chamber 20a via the valve 17b. A vacuum processing chamber 20b is provided. Two vacuum processing chambers are provided in order to increase the number of processed materials to be etched. Other components, such as the etching gas inlet and exhaust port,
It is omitted here. Next, the first and second vacuum processing chambers 20a and 20b will be described in detail.

FIG. 2 shows the first of the devices 10 shown in FIG.
It is a schematic structure explanatory view with which the structure of the 2nd vacuum processing chambers 20a and 20b is explained. Since these two vacuum processing chambers have the same configuration, only the first vacuum processing chamber 20a will be described.

The vacuum processing chamber 20a is provided with an upper electrode 21 and a lower electrode 23 for generating plasma, and is a so-called parallel plate type vacuum processing chamber. A high frequency power supply 2 for applying a high frequency of 13.56 MHz to the upper electrode 21.
5 is connected, and the lower electrode 23 is connected to the ground 27. The lower electrode 23 is also used as a stage on which the material A to be etched is placed. The upper electrode 21 can be moved up and down by a mechanism such as a cylinder, and the distance to the material to be etched can be adjusted.

The side wall 29 of the vacuum processing chamber 20a is made of an aluminum material having a high thermal conductivity, and a heater 31 and a first temperature sensor 33 are embedded in a part of the side wall 29. A temperature controller 35 for adjusting the heater temperature is connected to 31 and the first temperature sensor 33. The heater 31, the first temperature sensor 33, and the temperature controller 35 constitute a first temperature adjusting means 30 for adjusting the temperature inside the vacuum processing chamber 20a. In this example, the heater 31 is capable of heating up to 80 ° C.

Further, the heat exchanger 37 and the heat exchanger 37
And a part of the first heat medium circulation path 39a, which is connected to the first heat medium circulation path 39a passing through the inside of the upper electrode 21, and a portion of the first heat medium circulation path 39a provided in the circulation path inside the upper electrode 21. The second temperature sensor 41a for detecting the temperature of the circulating heat medium constitutes the second temperature adjusting means 40a for adjusting the temperature of the upper electrode 21.

Similarly, a heat exchanger 37 is connected to the heat exchanger 37, and a part of the heat exchanger 37 is connected to the lower electrode 23.
Of the second heat medium circulation path 39b passing through the inside of the second heat medium circulation path 39b
A third temperature sensor 41b, which is provided in the inner circulation path and detects the temperature of the circulating heat medium, constitutes second temperature adjusting means 40b for adjusting the temperature of the lower electrode 23. .

Here, a chiller is used as the heat exchanger 37, and a heater for heating the heat medium and a temperature controller are incorporated. Further, the same heat exchanger 37 is shared here in the second and third temperature adjusting means 40a and 40b. In addition, in FIG.
Although the third temperature sensors 41a and 41b are shown outside the first and second heat medium circulation paths 39a and 39b, in reality, these temperature sensors 41a and 4b are provided.
1b is provided in the heat medium circulation path. In this example, the upper electrode 21 and the lower electrode 23 can be heated to 110 ° C. by the second and third temperature adjusting means 40a and 40b.

The second temperature adjusting means 40a has a mechanism for adjusting the temperature of the upper electrode 21 as follows. The heat medium heated by the heater in the heat exchanger 37 is supplied from the heat medium supply port (not shown) of the first heat medium circulation path 39a connected to the heat exchanger 37, and the supplied heat medium is The heat medium circulation path 39a is returned to the chiller (heat exchanger 37) from an outlet (not shown). First heat medium circulation path 3
9a has a part thereof passing through the inside of the upper electrode 21 and a second temperature sensor 41a for detecting the temperature of the heat medium is provided in the first heat medium circulation path 39a. When the temperature is lowered, the temperature controller in the heat exchanger 37 adjusts the temperature of the heater so that the temperature is adjusted to a constant temperature. Further, the third temperature adjusting means 40b also has the same function as the second temperature adjusting means 40a.
The mechanism for adjusting the temperature of the lower electrode 23 is as follows. From the heat medium supply port (not shown) of the second heat medium circulation path 39b connected to the heat exchanger 37, the heat exchanger 37
The heat medium heated by the heater inside is supplied, and the supplied heat medium is returned to the heat exchanger 37 from the outlet (not shown) of the second heat medium circulation path 39b. A part of the second heat medium circulation path 39b passes through the lower electrode 23,
Further, a third temperature sensor 41b for detecting the temperature of the heat medium is provided in the second heat medium circulation path 39b. Regarding the configuration of the second vacuum processing chamber 20b, the first vacuum processing chamber 20
Since the configuration is exactly the same as that of a, the description is omitted.

Next, an etching method using the apparatus 10 will be described.

According to the etching method of the present invention, as already described, the upper electrode and the lower electrode for plasma generation are provided inside, and dry etching is performed on the material to be etched with the inside kept in vacuum. When performing dry etching with a dry etching apparatus having a vacuum processing chamber for performing the above and a preliminary chamber provided adjacent to the vacuum processing chamber and holding the inside of the vacuum processing chamber, the inside of the vacuum processing chamber and the upper part It has a feature in that each of the electrode and the lower electrode is simultaneously heated and etched at a constant temperature. Here, the material to be etched A
(FIG. 2) was used as a semiconductor wafer. Also, the object of removal is no longer needed after photolithography,
A TiN (titanium nitride) film was used as a reflection protection film. The reflection protection film is used to reduce the reflectance of the metal wiring during exposure to reduce light interference. Hereinafter, the etching method will be described with reference to FIGS. 1 and 2.

First, the first preliminary chamber 11 is replaced by the first preliminary chamber 11
An N ₂ (nitrogen) inlet (not shown) inside is purged with N _{2 to} attain atmospheric pressure. Then, the semiconductor wafer is transferred from the atmospheric transfer robot 100 to the first preliminary chamber 11 in the apparatus 10. Next, the inside of the first preliminary chamber 11 is evacuated. This is performed by a vacuum pump connected to a vacuum exhaust port (not shown) in the first preliminary chamber 11. Next, valve 1
3 is opened, and the semiconductor wafer is transferred to the second preliminary chamber 15. The second preliminary chamber 15 is always kept at a high vacuum so that the atmosphere does not flow into the vacuum processing chamber where the etching process is performed. Next, the valve 17a is opened, and the semiconductor wafer is moved to the first position by the transfer arm 15a of the second preliminary chamber 15.
It is transported to the vacuum processing chamber 20a. After that, dry etching is performed under the etching conditions described later. Next, in the same process, the valve 17b is opened to open the second preliminary chamber 20.
The semiconductor wafer is also transported to b, and etching processing is performed.
At this time, the inside of the vacuum processing chamber 10, the upper electrode 21, and the lower electrode 23 are simultaneously heated and maintained at a constant temperature. After the etching process is completed in the first vacuum processing chamber 20a, the semiconductor wafer is unloaded from the first vacuum processing chamber 20a by the transfer arm 15a of the second auxiliary chamber 15, and transferred through the valve 13 to the first auxiliary chamber 11 and the atmosphere. Robot 100
Sent to. The semiconductor wafer that has been dry-etched in the second vacuum processing chamber 20b is also sent to the atmospheric transfer robot 100 by the same process. By repeating this, the semiconductor wafers are sequentially etched.

Here, the etching conditions in the vacuum processing chamber will be described in detail. Table 1 shows materials to be etched in the first embodiment (removal target is a semiconductor wafer having a TiN film).
Shows the etching conditions for.

[0023]

[Table 1]

Here, RF power indicates high frequency power. Further, "EPD" in the section of etching time means that the end point detection method of the etching is detected by the end point detect method. Further, “OE = 40%” indicates that the overetching time was set 40% higher. For example, if it usually takes about 10 minutes to remove a film having a certain film thickness, this means that the etching time is set to 14 minutes.

After etching was carried out under the above conditions, it was examined by using H ₂ O ₂ (hydrogen peroxide solution) whether reaction products adhered to the vacuum processing chamber and the semiconductor wafer. When the reaction to the product and H ₂ O ₂ reacts, by utilizing the fact that the color yellow, the vacuum processing chamber 20a and the 20b, flowing the H ₂ O _2. As a result, no color developed in either the vacuum processing chamber or the semiconductor wafer. Therefore, it can be understood that the particles are not attached.

Under the conditions shown in Table 1, the TiN film was etched on 50 semiconductor wafers, and the wafers were numbered from 1 to 50 in the order in which they were etched. Wafer numbers 1, 13, 25, 26, With respect to the six wafers 38 and 50, the change in etching rate and the uniformity of etching within the wafer surface were examined. FIG. 3 shows the result. In particular, FIG. 3A is a graph showing changes in the etching rate (Å / min (min)) of six wafers, where the vertical axis represents the etching rate (Å / min (min)) and the horizontal axis represents The wafer numbers are shown in FIG. Also, FIG.
(B) is a graph showing the uniformity of etching on the wafer surface, where the ordinate represents the uniformity (±%) and the abscissa represents the wafer number.

Here, the etching rate is calculated using the following formula. (Average value of film thickness of film to be removed before etching-Average film thickness of film to be removed after etching) / etching time

Further, the uniformity means the uniformity of the etching rate within the surface of the wafer, which is calculated by using the following equations by calculating the etching rate at 9 points within the surface of each wafer. . {(In-plane maximum value of etching rate−in-plane minimum value of etching rate) / (in-plane maximum value of etching rate−in-plane minimum value of etching rate)} × 100

From FIG. 3A, the etching rate is
The range is 3100 to 3500 (Å / min), and it can be seen that the number does not decrease as the number of wafers processed increases. In addition, as shown in FIG.
The range is 9 (±%), and it can be seen that there is no decrease as the number of processed wafers increases. This indicates that the wafer is less likely to have a film residue.

Next, FIG. 4 shows the results of examining the temperature dependence of the etching rate of the TiN film. FIG. 4 shows the upper electrode 2
2 is a graph showing changes in the etching rate of the TiN film of each wafer (sample) when the temperatures of 1 and the lower electrode 23 are set to 60 ° C., 90 ° C., and 110 ° C., and the vertical axis indicates the etching rate (Å / Min), and the temperature (° C.) of the upper electrode and the lower electrode is plotted on the horizontal axis. As can be understood from this figure, the etching rate of the TiN film is 60% when the temperature of the upper electrode and the lower electrode is 60 ° C.
It shows about 2000 (Å / min) at 90 ℃,
In the case of, it shows about 2400 (Å / min). Also, 1
At 10 ° C., it shows about 3100 (Å / min), which shows that the etching rate improves almost in proportion to the temperature rise. Therefore, it is presumed that no TiN film residue remains.

<Second Embodiment> The second embodiment is basically the same as the first embodiment. Here, the etching apparatus, the etching method, the etching conditions, and the like are the same as those in the first embodiment, but the film to be removed is a polysilicon film instead of the TiN film. Then, under the conditions of Table 1 above, etching is performed on 50 semiconductor wafers, the wafers are numbered from 1 to 50 in the order of etching, and wafer numbers 1, 13, 25, 2
With respect to six wafers of 6, 38, and 50, changes in etching rate and etching uniformity within the wafer surface were examined. FIG. 5 shows the result. In particular, FIG. 5A shows the etching rate of 6 wafers (Å / min).
(Minutes)), in which the vertical axis represents the etching rate (Å / min (minutes)) and the horizontal axis represents the wafer number. Further, FIG. 5B is a graph showing the uniformity of etching within the wafer surface, where the ordinate represents the uniformity (±%) and the abscissa represents the wafer number.

From FIG. 5A, the etching rate is
A range of 3400 to 3800 (Å / min) is shown, and it can be seen that the number does not decrease as the number of processed wafers increases. In addition, as shown in FIG.
A range of 6 (±%) is shown, and it can be seen that this also does not decrease as the number of processed wafers increases. Therefore, it is difficult for the film to remain on the wafer.

Next, FIG. 6 shows the results of examining the temperature dependence of the etching rate of the polysilicon film. FIG. 6 shows the temperatures of the upper electrode 21 and the lower electrode 23 at 60 ° C. and 90 ° C., respectively.
3 is a graph showing changes in the etching rate of the polysilicon film of each wafer (sample) at temperatures of 110 ° C. and 110 ° C., with the etching rate (Å / mi
n) and the temperature (° C.) of the upper electrode and the lower electrode is plotted on the horizontal axis. As can be understood from this figure, the etching rate of the polysilicon film is almost 3500 (Å
/ Min), indicating that the etching rate does not decrease as the temperature rises. Therefore, it is presumed that no film residue of the polysilicon film is generated.

<Third Embodiment> The first embodiment and etching apparatus, etching method, etching conditions, etc.
Same as in the first embodiment, except that after the semiconductor wafer is transferred to the first and second processing chambers, the heater 31 and the heat exchanger 37 are operated, and the wafer is left for 10 to 30 seconds. The wafer temperature was stabilized. When the etching process was performed after this, the variation (uniformity) of the etching rate within the wafer surface was improved. For example, the uniformity is ± 13.8% when the wafer is not left standing.
When the etching was carried out under the same conditions as above, the uniformity was ± 5.2%. Therefore, it was found that the one in which the wafer temperature was stabilized improved in uniformity.

Since the other parts are the same as those in the first embodiment, detailed description thereof will be omitted.

It is obvious that the present invention is not limited to the above-mentioned first, second and third embodiments. For example, although an etching apparatus having two vacuum processing chambers is used here, the number of vacuum processing chambers may be one. Further, here, the temperature control means in the vacuum processing chamber,
Although the temperature adjusting means for the upper and lower electrodes are different, they may be the same or different. For example, all temperature control means are heaters,
The temperature adjusting means may include a temperature sensor and a temperature controller, or all the temperature adjusting means may include a heat exchanger, a heat medium circulation path, and a temperature sensor.

Although one heat exchanger is shared by the temperature adjusting means for the upper electrode and the lower electrode here, they may be used independently. In addition, the upper electrode, the lower electrode, the temperature control means in the vacuum processing chamber are all heat exchangers,
Also in the case where the temperature adjusting means including the heat medium circulation path and the temperature sensor is used, one heat exchanger may be shared or may be independently used.

[0038]

As is apparent from the above description, according to the dry etching method of the present invention, the vaporization of the reaction product generated during etching is promoted, and the reaction product is generated in the vacuum processing chamber and the surface of the material to be etched. It is possible to prevent adhesion of particles due to the object with a further effect.

Therefore, there is little concern that a film of the material to be etched will remain, and etching can be performed with high processing accuracy.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing an example of a dry etching apparatus.

FIG. 2 is a schematic sectional view of a vacuum processing chamber.

FIG. 3A is a graph showing changes in the etching rate of TiN films on six wafers, and FIG. 3B is a graph showing the uniformity of etching within the wafer surface.

FIG. 4 is a graph showing the temperature dependence of the etching rate of a TiN film.

FIG. 5A is a graph showing changes in etching rate of polysilicon films of six wafers, and FIG. 5B is a graph showing uniformity of etching within the wafer surface.

FIG. 6 is a graph showing the temperature dependence of the etching rate of a polysilicon film.

[Explanation of symbols]

10: Dry etching device 11: First spare room 13, 17a, 17b: valve 15: Second spare room 20a: First vacuum processing chamber 20b: second vacuum processing chamber 21: Upper electrode 23: Lower electrode 25: High frequency power supply 27: Ground 29: Side wall 30: First temperature adjusting means 31: Heater 33: First temperature sensor 35: Temperature controller 37: Heat exchanger (chiller) 39a: First heat medium circulation path 39b: Second heat medium circulation path 40a: Second temperature adjusting means 40b: Third temperature adjusting means 41a: Second temperature sensor 41b: Third temperature sensor

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 4M106 AA01 BA10 BA12 CA41 CA70                       CB30                 5F004 AA13 BA04 BB18 BB26 BB32                       CA04 CA08 CA09 DB00 DB02                       DB12

Claims (12)

[Claims] 1. A mounting process of mounting a material to be etched on the lower electrode in a vacuum processing chamber having an upper electrode and a lower electrode; and heating the inside of the vacuum processing chamber, the upper electrode and the lower electrode. A dry etching method comprising: a heating step; and a dry etching step of performing a dry etching treatment on the material to be etched. 2. The dry etching method according to claim 1, wherein in the heating step, the upper electrode and the lower electrode are heated by a heat medium supplied from a heat exchanger. . 3. The dry etching method according to claim 1, wherein in the heating step, the inside of the vacuum processing chamber is heated by a heater embedded in a sidewall of the vacuum processing chamber. Dry etching method. 4. The dry etching method according to any one of claims 1 to 3, wherein the dry etching step includes 10 seconds to 30 seconds from the start of the heating step.
A dry etching method, which is performed after a lapse of seconds. 5. The dry etching method according to claim 1, wherein a high-frequency voltage is applied to the upper electrode in the dry etching process step. 6. The dry etching method according to claim 1, wherein the material to be etched is titanium nitride formed on a semiconductor wafer. 7. The dry etching method according to claim 1, wherein the material to be etched is a polysilicon film formed on a semiconductor wafer. 8. A first auxiliary chamber, a second auxiliary chamber connected to the first auxiliary chamber via a first valve, and a vacuum processing chamber connected to the second auxiliary chamber via a second valve. In a dry etching method for performing dry etching on a material to be etched in a dry etching apparatus having a, a semiconductor wafer on which the material to be etched is formed is transferred to the first preliminary chamber at atmospheric pressure. And a step of evacuating the first preliminary chamber in which the semiconductor wafer is transferred, the first valve is opened, and the first preliminary chamber is moved to the second preliminary chamber which is in a vacuum state in advance. A step of loading a semiconductor wafer; a step of opening the second valve to transfer the semiconductor wafer from the second preliminary chamber to the vacuum processing chamber which is in a vacuum state in advance; the upper electrode and the lower electrode By supplying the heat medium, a dry etching method which comprises a step of performing dry etching with respect to the material to be etched while controlling the temperature of the upper electrode and the lower electrode. 9. A dry etching method, comprising: supplying a heating medium to the upper electrode and the lower electrode while performing dry etching on the material to be etched arranged on the lower electrode. 10. The dry etching method according to claim 9, wherein the heat medium supplied to the upper electrode and the lower electrode is supplied from a common heat exchanger. 11. The dry etching method according to claim 9, wherein the heating medium is supplied to the upper electrode and the lower electrode to adjust the temperature of the upper electrode and the lower electrode, A dry etching method characterized in that dry etching is performed on a material to be etched. 12. A dry etching method, wherein dry etching is performed on a material to be etched arranged on the lower electrode while heating the upper electrode and the lower electrode with a heating medium.