JPH0629259A - Semiconductor manufacturing apparatus - Google Patents

Abstract

PURPOSE:To improve an ashing rate and improve element characteristics even if a substrate temperature is lowered by providing a magnetic field generating means for generating a magnetic field to prevent evacuation of oxygen in an ashing treatment chamber. CONSTITUTION:Oxygen radical flows, passing through a hole on the plasma shielding plate 13, to a stage 10 loading wafers and an ashing treatment chamber 12 provided under the stage 10 and having a gas evacuation port 11. A magnetic field generating means 1 made of a permanent magnet is provided within the side of sidewall of stage 10 and ashing treatment chamber 12 provided opposed thereto within the ashing treatment chamber 12. Thereby, the oxygen radical can be trapped efficiently in the proximity to the wafer 9 on the stage 10 in such a manner that the oxygen radical is prevented from penetrating into the side of evacuation port of the stage F. Accordingly, the ashing rate can be enhanced even if the wafer temperature is lowered.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing apparatus, and more particularly, it can be applied to an oxygen ashing apparatus used for resist stripping and the like, a dry etching apparatus for dry etching a silicon-based film, and the like. When etching a resist or the like with an ashing device, the ashing rate can be improved even if the substrate temperature is low, and when etching a silicon-based film with a dry etching device, the silicon-based film can be etched without lowering the etching rate. The present invention relates to a semiconductor manufacturing apparatus capable of etching the above film and making it difficult to etch a resist and an oxide film which are not desired to be etched.

In recent years, a photoresist used for patterning is stripped by a dry ashing apparatus which normally uses oxygen plasma. With higher integration and higher speed of devices, plasma damage is more likely to affect the substrate, and there is a demand for an ashing device that does not damage the substrate and that can obtain a high ashing rate.

Further, with the demand for higher integration and higher speed of devices, a more advanced dry etching technique for forming a pattern is required. Above all, it is necessary to obtain a vertical shape faithful to the resist mask without etching a film other than the film to be etched, such as a resist mask or an underlying oxide film.

[0004]

2. Description of the Related Art Conventionally, an oxygen plasma ashing apparatus used for resist stripping has a type of ashing treatment in oxygen plasma and a method of extracting only oxygen radicals (also called oxygen active species) of neutral active species from the oxygen plasma. There are two types of downflow types that perform ashing processing. In this latter downflow type ashing apparatus, a plasma generation chamber and a wafer ashing processing chamber are separately provided so that the plasma is not directly exposed to the wafer. Therefore, in the case of the former plasma ashing type This has the advantage that the damage to the wafer due to plasma can be reduced.

By the way, in a conventional dry etching apparatus for a silicon-based film, oxygen is further added as a radicalization accelerator to a fluorine-based gas or a chlorine-based gas in a plasma generation chamber to generate a fluorine radical and a chlorine radical. A type is known in which a silicon-based film of a wafer in an etching processing chamber is etched by the generated fluorine radicals and chlorine radicals.

[0006]

In the conventional down-flow type oxygen plasma ashing apparatus described above, the ashing rate should be increased if the substrate temperature is raised because the resist etc. are ashed by utilizing a chemical reaction by oxygen radicals. However, if the substrate temperature is set to a high temperature of 150 ° C or higher, contaminants may enter the semiconductor,
There has been a problem that the low melting point wiring such as Al is deteriorated and the element characteristics are deteriorated.

For this reason, the device characteristics are prioritized, for example, 10
When ashing is performed at a low temperature of 0 ° C. or lower, there is a problem that the ashing rate is remarkably lowered because the chemical reaction is utilized as described above. Next, in the conventional dry etching apparatus for a silicon-based film described above, oxygen was introduced in order to increase the generation rate of fluorine radicals and chlorine radicals and increase the etching rate, so this oxygen was also turned into plasma. There is a problem in that the etching rate of a resist or an oxide film such as a gate oxide film, which serves as a mask that is not desired to be etched by oxygen plasma, is increased, and the resist and the oxide film are etched. In the worst case, the resist mask may be completely removed, or the gate oxide film or the like may be etched to cause a breakdown voltage defect or the like.

Therefore, according to the present invention, when ashing a resist or the like with a downflow type ashing apparatus, the ashing rate can be improved even when the substrate temperature is low, the element characteristics can be improved, and dry etching can be performed. When etching a silicon-based film with a device, it is possible to etch the silicon-based film without lowering the etching rate, and it is difficult to etch a resist mask or an oxide film such as a gate oxide film that is not desired to be etched. It is an object of the present invention to provide a semiconductor manufacturing apparatus capable of manufacturing the semiconductor.

[0009]

In order to achieve the above object, a semiconductor manufacturing apparatus according to the present invention comprises a plasma generation chamber into which oxygen gas is introduced, and a mounting table which is placed under the plasma generation chamber and on which a wafer is mounted. In a semiconductor manufacturing apparatus for performing downflow type dry ashing including an ashing processing chamber having a gas exhaust port, a magnetic field generating unit for generating a magnetic field for preventing oxygen from being exhausted is provided in the ashing processing chamber. Is.

In the present invention, the magnetic field generating means is
It is preferable to provide it on the side of the stage wall and on the side wall of the ashing chamber facing it, and in this case, oxygen radicals below the stage are generated by the magnetic field of the magnetic field generating means provided on the side wall of the stage and the side wall of the ashing chamber opposite thereto. Since it can be prevented from permeating to the exhaust port side, the oxygen radicals can be more efficiently confined in the vicinity of the wafer on the stage than when the magnetic field generating means is provided under the stage, and the use efficiency of the oxygen radicals can be improved. Wear.

In order to achieve the above object, the semiconductor manufacturing apparatus according to the present invention comprises a plasma generation chamber into which a fluorine-based or chlorine-based gas and an oxygen gas are introduced, and a mounting table adjacent to the plasma generation chamber for mounting a wafer. In a semiconductor manufacturing apparatus that performs dry etching including an etching processing chamber having a gas exhaust port, a magnetic field that prevents oxygen from advancing toward the wafer is provided between the wafer in the etching processing chamber and the plasma generation chamber. A magnetic field generating means for generating is provided.

In the present invention, the magnetic field generating means is
It is preferable to provide the space between the plasma generation chamber and the etching treatment chamber. In this case, the magnetic field of the magnetic field generation means provided between the plasma generation chamber and the etching treatment chamber prevents oxygen from going to the oxygen etching treatment chamber. It can be confined in the plasma generation chamber to increase the amount of oxygen in the plasma generation chamber to increase the efficiency of generating fluorine radicals and chlorine radicals. Can make it difficult to etch a silicon-based film) an oxide film and a resist.

[0013]

First, the operation of the invention according to claims 1 and 2 will be described. FIG. 1 is a diagram illustrating the principle of the present invention. Figure 1
In (a), a magnetic field 2 is generated between the N pole 1a and the S pole 1b of the magnetic field generation means 1, and nitrogen passes through the magnetic field 2 between the N pole 1a and the S pole 1b, but oxygen passes through. It shows that it does not exist.

The present inventor has noticed that, as shown in FIG. 1, the phenomenon that oxygen is not permeated to the surface due to the presence of a magnetic field of a certain strength (1 k Gauss or more) is already known, and this is taken into consideration. I applied it to a downflow type ashing device. That is, in the present invention, a magnetic field generating means for generating a magnetic field for preventing exhaustion of oxygen radicals is provided in the ashing chamber below the plasma generating chamber, and preferably the stage sidewall and the ashing chamber facing the stage sidewall are provided. It may be provided on the side wall. Therefore, by confining the oxygen radicals escaping by the downflow in the ashing process chamber by the magnetic field generated by the magnetic field generating means, it is possible to efficiently use the oxygen radicals that have been conventionally exhausted without being used for the ashing. . As a result, the ashing rate can be increased even at the same wafer temperature as the conventional one, and the ashing rate can be increased even at a low wafer temperature. For this reason,
It is not necessary to raise the wafer temperature to a high temperature, and it is possible to suppress deterioration of element characteristics due to the high temperature. Moreover, since it is a down-flow type, the original advantage of less damage to the wafer can be utilized. Furthermore,
As described above, when the magnetic field generating means is provided on the side wall of the stage and the side wall of the ashing processing chamber facing the side wall of the stage, oxygen radicals are generated under the stage by the magnetic field of the magnetic field generating means provided on the side wall of the stage and the side wall of the ashing processing chamber facing the side wall of the stage. Since it can be prevented from permeating to the exhaust port side, the oxygen radicals can be more efficiently confined in the vicinity of the wafer on the stage than when the magnetic field generating means is provided under the stage, and the use efficiency of the oxygen radicals can be improved. You can

Next, the operation of the invention according to claims 3 and 4 will be described. The inventor uses the same principle as in FIG.
Focusing on the already known phenomenon that oxygen is not transmitted to the surface due to the presence of a magnetic field of a certain strength, we applied this to a dry etching apparatus. When etching a silicon-based film using a fluorine-based or chlorine-based gas with a dry etching device, when generating fluorine or chlorine radicals with plasma of a fluorine-based or chlorine-based gas, mix oxygen as described above. It is known that the production amount of fluorine and chlorine radicals is increased by the above. The etching rate of the silicon-based film can be increased by increasing the amount of fluorine and chlorine radicals. On the other hand, oxygen radicals are also generated, and the generated oxygen radicals also have a function of increasing the etching rate of the resist or the oxide film type film which should not be etched. Therefore, when plasma is generated, the amount of fluorine and chlorine radicals generated is increased. Therefore, an oxygen mixed atmosphere is used in the plasma generation chamber, but it is preferable that there is no oxygen atmosphere on the wafer surface in the etching processing chamber.

Therefore, in the present invention, a magnetic field generating means for generating a magnetic field for preventing oxygen from advancing toward the wafer is provided between the wafer in the etching processing chamber and the plasma generating chamber, and preferably the etching processing chamber and the plasma are provided. It may be provided between the production chambers. Of course, if the gas flow is fast, it cannot be blocked, but it can be sufficiently blocked by the plasma extraction of ECR. Therefore, as shown in FIGS. 2A and 2B, it is possible to prevent the oxygen atmosphere from reaching the wafer surface side by the magnetic field of the magnetic field generating means 1, so that the resist or oxide film which is not desired to be etched is removed. You can make it hard to be etched. Moreover, since chlorine radicals and fluorine radicals can be introduced into the wafer through the magnetic field, the silicon-based film can be etched as in the conventional case. Further, as described above, if the magnetic field generating means is provided between the plasma generation chamber and the etching treatment chamber, oxygen can be confined in the plasma generation chamber, so that the generation efficiency of fluorine and chlorine radicals can be increased.

Incidentally, FIG. 2A shows a state in which chlorine radicals can be transmitted by the magnetic field of the magnetic field generating means 1 but oxygen radicals cannot be transmitted, and FIG. 2B shows the present invention in which the magnetic field generating means is provided. FIG. 9 is a diagram showing the respective etching rates of resist, SiO ₂ , and Si in the conventional case not provided.

[0018]

(Embodiment 1) FIG. 3 is a schematic diagram showing the structure of a semiconductor manufacturing apparatus according to Embodiment 1 of the present invention. The semiconductor manufacturing apparatus of the illustrated example is applied to a downflow type ashing apparatus by microwave excitation. 3, the same reference numerals as those in FIG. 1 denote the same or corresponding parts.
Is a microwave generation means for generating a microwave of 2.45 GHz, and the microwave generated by this microwave generation means 5 is introduced into the plasma generation chamber 8 through the microwave waveguide 6 and the transmission window 7. , This plasma generation chamber 8
Oxygen gas is also introduced into. At this time, the micro power is 1.0 Kw, and the oxygen gas introduction amount is 1 SLM. Then, the introduced microwave excites the oxygen gas to generate oxygen radicals in the plasma generation chamber 8. Next, the generated oxygen radicals pass through the holes formed in the plasma shield plate 13 in a mesh shape and pass through the substantially circular stage 10 on which the wafer 9 is placed and the gas exhaust port 11 arranged below the stage 10. It flows to the ashing processing chamber 12 side that it has. Inside the ashing chamber 12, the side wall of the stage 10 and the side wall of the ashing chamber 12 facing the stage 10 are provided with the magnetic field generating means 1 composed of a permanent magnet. Either the N pole or the S pole may be provided on the side wall of the stage 10 and the side wall of the ashing chamber 12 facing the side wall of the stage 10, and the essential point is to provide the poles facing each other so that a magnetic field is generated therebetween. The magnet may be attached by screwing or the like. As described above, the cylindrical magnetic field can be generated by providing the magnetic field generating means 1 on the side wall of the ashing chamber 12 facing the stage 10 having a substantially circular shape. The magnetic field strength at this time is 1 K gauss.
As the ashing conditions, the oxygen flow rate was 1 liter / min, the pressure was 1 Torr, and the stage temperature was 80 ° C.

As a result, in this embodiment, as shown in FIG. 4, the ashing rate can be increased even at the same wafer temperature as compared with the comparative example which was performed under the same conditions except that the magnetic field generating means 1 was provided. It was found that the ashing rate can be increased even when the wafer temperature is low. Therefore, it is possible to obtain a sufficient ashing rate without raising the wafer temperature to a high temperature. Therefore, it is possible to avoid raising the temperature to a high temperature, and it is possible to suppress deterioration of element characteristics due to the high temperature. Moreover, since it is a down-flow type, the original advantage of less damage to the wafer can be utilized.

In the first embodiment, the magnetic field of the magnetic field generating means 1 provided on the wall side of the stage 10 and the wall side of the ashing chamber 12 facing the wall of the stage 10 prevents oxygen radicals from permeating to the exhaust port side under the stage. Although the case where the oxygen radicals can be efficiently confined in the vicinity of the wafer 9 on the stage 10 has been described above, the present invention is not limited to this, and for example, when the magnetic field generating means is provided under the stage. May be

(Embodiment 2) Next, FIG. 5 is a schematic diagram showing the structure of a semiconductor manufacturing apparatus according to Embodiment 2 of the present invention.
The semiconductor manufacturing apparatus in the illustrated example is applied to an ECR etching apparatus. 5, the same reference numerals as those in FIG. 1 indicate the same or corresponding portions, and 21 is a microwave generation means for generating a microwave of 2.45 GHz, and the microwave generated by this microwave generation means 21 is a microwave guide. It is introduced into the plasma generation chamber 25 surrounded by the ECR coil 24 through the wave tube 22 and the transmission window 23, and chlorine gas and O ₂ gas are also introduced into the plasma generation chamber 25. The pressure at this time was 2 mTorr, and the microwave power was 2.
The RF power is set to 0 Kw, the RF power is set to 50 w, and the chlorine gas / oxygen gas introduction amount is set to 90/10 sccm. On the other hand, in the etching processing chamber 26, for bias application (13.56 MH
A wafer 30 is placed on a sample table 29 having a substrate holder 28 connected to a high frequency power source 27 (z, 100 w), and an exhaust port 31 for exhausting gas is provided. Magnetic field generating means 1 composed of a permanent magnet for preventing oxygen from being transmitted between the plasma generating chamber 25 and the etching processing chamber 26 toward the wafer 30.
Is provided. The magnetic field generating means 1 may be arranged with either N poles or S poles, and the essential point is to provide opposing poles so as to generate a magnetic field therebetween. The magnet may be attached by screwing or the like. The magnetic field strength at this time is 1 K gauss.

As a result, when the polysilicon is etched, the etching rate of the polysilicon is 4000 Å / min and the etching rate of the resist is 5 in this embodiment.
00 Å / min, the etching rate of the oxide film is 50 Å / min. Polysilicon 3000 Å / min, resist 2000 Å / min, oxide film 500 Å / min in the comparative example performed under the same conditions except that the magnetic field generating means 1 is provided. In comparison, it was possible to reduce the amount of resist and oxide film loss without lowering the etching rate of the polysilicon film.

Further, as can be seen from FIG. 6, in the comparative example in which the magnetic field generating means 1 is not provided, as the oxygen is introduced, the SiO ₂ etching resistance ratio deteriorates, whereas
In this embodiment, it can be seen that even if oxygen is introduced, the SiO ₂ -resistant etching selection ratio can be increased. In the above embodiment, it is preferable that the magnetic field generating means 1 is provided between the plasma generating chamber 25 and the etching processing chamber 26, and oxygen is confined in the plasma generating chamber 25 by the magnetic field of the magnetic field generating means 1 to enhance the generation efficiency of chlorine radicals. Although the case of the embodiment has been described, the present invention is not limited to this, and the point is that it may be provided between the wafer 30 and the plasma generation chamber 25 so that oxygen does not advance toward the wafer 30.

[0024]

According to the present invention, when ashing a resist or the like with a downflow type ashing apparatus, the ashing rate can be improved and the device characteristics can be improved even when the substrate temperature is low. effective. Further, when etching a silicon-based film with a dry etching device, the silicon-based film can be etched without lowering the etching rate, and an oxide film such as a resist mask or a gate oxide film which is not desired to be etched can be removed. This has the effect of making it difficult to etch.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a diagram illustrating the principle of the present invention.

FIG. 3 is a schematic diagram showing a configuration of a semiconductor manufacturing apparatus according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a change in ashing rate with respect to a change in stage temperature when the magnetic field generating means of the present invention is provided and when the magnetic field generating means of the comparative example is not provided.

FIG. 5 is a schematic diagram showing a configuration of a semiconductor manufacturing apparatus according to a second embodiment of the present invention.

FIG. 6 shows O ₂ / Cl ₂ + when the magnetic field generating means of the present invention is provided and when the magnetic field generating means of the comparative example is not provided.
Is a diagram showing an SiO ₂ etching characteristics with respect to O ₂ ratio.

[Explanation of symbols]

 1 magnetic field generation means 1a N pole 1b S pole 5 microwave generation means 6 microwave waveguide 7 transmission window 8 plasma generation chamber 9 wafer 10 stage 11 gas exhaust port 12 ashing chamber 13 plasma shield 21 microwave generation means 22 microwave Waveguide 23 Transmission window 24 ECR coil 25 Plasma generation chamber 26 Etching chamber 27 High frequency power supply 29 Sample stage 30 Wafer 31 Exhaust port

Claims (4)

[Claims] 1. A plasma generation chamber (8) into which oxygen gas is introduced, a mounting table (10) disposed below the plasma generation chamber (8) for mounting a wafer (9), and a gas exhaust port (11). And a ashing treatment chamber (12) having a magnetic field for generating oxygen in the ashing treatment chamber (12) for preventing oxygen from being discharged into the ashing treatment chamber (12). A semiconductor manufacturing apparatus comprising a generating means (1). 2. The semiconductor manufacturing apparatus according to claim 1, wherein the magnetic field generating means (1) is provided on a wall side of the stage (10) and a side wall of the ashing processing chamber (12) facing the wall side. 3. A plasma generation chamber (25) into which a fluorine-based or chlorine-based gas and oxygen gas are introduced, and a mounting table (29) which is adjacent to the plasma generation chamber (25) and on which a wafer (30) is mounted. In a semiconductor manufacturing apparatus for performing dry etching including an etching processing chamber (26) having a gas exhaust port (31), the wafer (30) and the plasma generation chamber (25) in the etching processing chamber (26). Magnetic field generating means (1) for generating a magnetic field for preventing oxygen from advancing in the direction of the wafer (30).
A semiconductor manufacturing apparatus comprising: 4. The semiconductor manufacturing apparatus according to claim 3, wherein the magnetic field generating means (1) is provided between the plasma generating chamber (25) and the etching processing chamber (26).