JPH09232281A - Dry-etching treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dry etching treatment method in which a high selectivity ratio is compatatible with a fine working operation by a method wherein the temperature of a sample is changed between an etching treatment and an etching treatment at a step succeeding it and the etching treatments at different temperatures are executed. SOLUTION: A W polycide layer which is composed of a polysilicon layer 32 and a WSix layer 33 is formed on an SiO2 film 31 on a silicon substrate 30. In addition, the W polycide layer at a sample W in which a photoresist pattern 34 is formed on it is etched and treated, and the layer is worked to a pattern shape corresponding to the resist pattern 34. At this time, a main etching operation at room temperature is performed as a first step, and an etching operation at a low temperature is performed as a second step succeeding it. Thereby, even when a sidewall protective film which is formed is thin, it is possible to restrain a radical reaction due to a low temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching processing method mainly used for manufacturing a semiconductor device, and more particularly to a dry etching processing method which realizes both anisotropic processing and a high selection ratio.

[0002]

2. Description of the Related Art In recent years, the demand for microfabrication in VLSIs has become increasingly severe. A compatible treatment method is indispensable. By the way, when a material other than an oxide film is plasma-etched, anisotropic shape is ensured by the existence of a so-called sidewall protective film, as is well known. That is, this side wall protective film is
Various deposits, including organic polymers, are formed by the reaction products generated during plasma etching being re-dissociated in the plasma, and are formed by depositing on the sidewalls of the pattern. And protects the side walls from being etched.

However, since the side wall protective film is formed by deposits from reaction products, if the pattern formed by etching is convex, the side wall protective film is relatively thick if the width is small. It becomes too large, and the overall pattern width becomes thicker than the desired width. Similarly, when the pattern formed by etching is a concave groove, if the width is small, the side wall protective film becomes relatively too thick, and the overall pattern width is made smaller than desired. Therefore, as the miniaturization of various patterns progresses and the pattern width becomes thin (narrow) as described above, the dimensional accuracy of the obtained pattern decreases when the anisotropy of etching is secured by using the sidewall protection film. It does.

In order to solve such inconvenience, recently,
Attempts have been made to secure dimensional accuracy by performing etching while performing high-speed exhaust, and attention has been paid. This high-speed evacuation process shortens the residence time of the etching gas during the etching process by installing a pump having a higher evacuation speed than the conventional etching processing apparatus and improving the conductance of the etching gas. This suppresses the reaction products from being redissolved in the plasma during the treatment. According to such a high-speed exhaust process, the amount of deposits due to the re-dissociation of reaction products can be significantly reduced.
The absolute value of the dimensional conversion difference and its variation can be suppressed very effectively.

[0005]

However, in the above-described high-speed exhaust process, the reaction product is quickly exhausted, so that the supply source of the side wall protective film is reduced and the side wall protective film is formed to a sufficient thickness. As a result, the anisotropic shape is insufficiently secured, which causes a new problem that the shape accuracy of the pattern obtained when overetching is deteriorated. In other words, when over-etching, if the substrate application bypass is lowered to secure the selection ratio with the base, the side wall protective film is thin and therefore weak,
Occurrence of side etching and notching becomes unavoidable, and conversely, if the applied bias is increased to secure the shape, then the selection ratio with respect to the underlying layer will decrease.

As a technique for solving the problem of the trade-off between the selectivity and the shape as described above and achieving both the selectivity and the anisotropic shape, the wafer temperature during etching is cooled to 0 ° C. or less. A so-called low-temperature etching technique has been proposed. This low temperature etching technology was reported by, for example, a group of Mr. Taji et al. (Hitachi Chuken) (1988 DRYPR
OCESS SYMPOSIUM "Low-Temperature Microwave Plasma
Etching ”), in which the radical reaction is suppressed by lowering the sample temperature, and anisotropy can be ensured even under a low substrate bias.

However, even in this low temperature etching technique, when the vapor pressures of the reaction products are different between WSi _x and polysilicon, such as W polycide, a temperature that can effectively lower the temperature is obtained. Since it is difficult to set the temperature, that is, set the temperature at which etching can be performed while ensuring the anisotropic shapes of both, it is the actual situation that it has not been effectively put to practical use. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a dry etching method capable of achieving both a high selection ratio and high-precision fine processing.

[0008]

The present invention has been made by paying attention to the advantages of the low temperature etching technique. In the dry etching method according to claim 1, the sample is etched by a plurality of steps. In the same processing apparatus, the temperature of the sample is changed between the etching process of one of the steps and the etching process of the subsequent step, and the one step and the subsequent step are performed. Performing etching treatment at different temperatures depending on the step is the means for solving the above-mentioned problems.

That is, according to this dry etching method, since the sample temperature is changed between the etching processing of one step and the etching processing of the subsequent steps, for example, the main etching processing is performed at room temperature as one step. If the overetching process is performed at a low temperature as a subsequent step, the radical reaction can be suppressed during the overetching process as described above even if the formed sidewall protection film is thin and the temperature is lowered. You will be able to withstand excessive radical attacks. Therefore, due to the effect of suppressing the radical reaction due to the lowering of the temperature, the occurrence of undercut or notching can be prevented even when the bias applied to the sample is reduced. In addition, since each etching process is performed in the same processing apparatus, it is possible to shorten the time required for changing the sample temperature between steps.

In the dry etching method according to the fourth aspect of the present invention, when the etching process including a plurality of steps is repeatedly performed on a plurality of samples in the same processing apparatus, the first step among the steps is performed. Between the etching process and the etching process of the final step, the temperature of the sample supporting the sample is changed to change the temperature of the sample, and the etching process of different temperatures is performed in the first step and the final step. Done,
And, when the etching process of the final step is completed, before putting the next sample into the processing apparatus, to the sample set temperature in the etching process of the first step,
Changing the temperature of the sample table was used as a means for solving the above problems.

According to this dry etching method,
Since the etching process at the different temperature is performed between the etching process of the first step and the etching process of the final step, the same effect as the invention of claim 1 can be obtained,
Furthermore, after the etching process of the final step is completed, the temperature of the sample stage is changed to the sample set temperature in the etching process of the first step before the next sample is put in the same processing apparatus. After the etching process of one sample is completed, the time until the etching process of the next sample is started is shortened.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The dry etching method of the present invention will be described in detail below. First, an etching apparatus suitable for carrying out the processing method of the present invention will be described with reference to FIG. In FIG. 4, reference numeral 1 is a plasma etching apparatus (hereinafter, simply referred to as an etching apparatus). The etching apparatus 1 is configured to include a helicon wave plasma generation source having RF antennas installed at two locations and a stage movable in the vertical direction.
The RF antennas 3 and 3 provided on the diffusion chamber 2, the RF antenna 4 provided on the top plate 2a of the diffusion chamber 2 in a loop, and the diffusion chamber 2
And a multi-pole magnet 5 which is provided outside the lower part of the above and forms a cusp magnetic field for suppressing the disappearance of electrons at the wall. The RF antennas 3, 3 are provided around the outside of a bell jar 6 formed of a cylindrical quartz tube having a diameter of 350 mm formed in the upper part of the diffusion chamber 2, and have an antenna shape in which M = 1 mode plasma stands. belongs to. A solenoid coil assembly 7 including an inner peripheral coil and an outer peripheral coil is arranged outside the RF antennas 3 and 3. The inner peripheral coil of the solenoid coil assembly 7 contributes to the propagation of the helicon wave, and the outer peripheral coil contributes to the transportation of the generated plasma. A power source 9 is connected to the RF antennas 3 and 3 via a matching network 8, and the RF antenna 4 is connected to the matching network 10.
The power supply 11 is connected via.

A stage (sample stage) 12 for supporting and fixing a sample W made of a wafer or the like is provided in the diffusion chamber 2, and an exhaust port 13 for exhausting the gas in the diffusion chamber 2 is further provided. It is formed by being connected to negative pressure means (not shown) such as a vacuum pump. Stage 12
Is a lifting mechanism (not shown) for moving the sample W up and down.
And a wafer contact mechanism (not shown) using an electrostatic chuck with a heater, which is connected to a bias power source 14 for controlling the ion energy incident on the sample W.

The stage 12 is also provided with a refrigerant pipe 1
Chiller 17 is connected via 5 and 16, and sample W
A fluorescent fiber thermometer 18 for measuring the temperature is connected. The chiller 17 is made of He gas or the like-14.
The gas refrigerant of 0 ° C. is supplied to the stage 12 through the refrigerant pipe 15, and the refrigerant returned from the stage 12 is received through the refrigerant pipe 16 and further cooled to a predetermined temperature. Is used to cool the sample W supported and fixed on the stage 12.
The refrigerant pipe 15 connected to the chiller 17 is provided with an electronic control valve 20 capable of operating at cryogenic temperature, and the bypass pipe 21 between the refrigerant pipe 15 and the refrigerant pipe 16 is also operated at cryogenic temperature. An electronic control valve 22 capable of performing the above is provided.

Here, the degree of cooling of the sample W is controlled by the flow rate of the refrigerant supplied from the chiller 17. That is, in order to cool the stage 12 to cool the temperature of the sample W to a desired temperature, the temperature detected by the fluorescent fiber thermometer 18 is detected by the control device (PID controller) 23 and is preset here. Based on the difference from the temperature of the sample W, the controller 23 controls the opening / closing degree of the electronic control valves 20 and 22 so that the gas refrigerant flow rate is determined in advance by experiments or calculations. In FIG. 4, details of the apparatus such as the etching gas introduction hole and the gate valve are omitted.

Next, a first embodiment of the dry etching method of the present invention using such an etching apparatus 1 will be described with reference to FIGS. 1 (a) to 1 (c). This processing method is an example in which the method of the present invention is applied to a method of processing W polycide by a two-step etching process. That is, in this example, as shown in FIG. 1A, a W polycide including a polysilicon layer 32 and a WSi _x layer 33 is formed on a SiO ₂ film 31 on a silicon substrate 30, and a photo film is formed on the W polycide. The W polycide of the sample W on which the resist pattern 34 is formed is subjected to an etching treatment to process it into a pattern shape corresponding to the photoresist pattern 34. The first step is main etching at room temperature, and the second step is low temperature. Over etching is performed.

[0017] First, the main etching of the first step by a normal temperature (20 ° C.) under the following conditions, and a WSi _x layer 33 and the polysilicon layer 32 as shown in FIG. 1 (b),
The polysilicon layer 32 is removed by etching until a part thereof is left. First step (main etching) etching gas; Cl ₂ / O ₂ 50/10 SCCM pressure; 5 mTorr source power 1 (RF antenna 4); 2500 W (1
3.56Hz) Source power 2 (RF antennas 3, 3); 2500W
(13.56 Hz) RF bias; 100 W Sample temperature; 20 ° C. For the sample temperature adjustment here, refer to Stage 12
The heater of the electrostatic chuck (not shown) provided in the above is used together with the cooling by the chiller 17, and in particular, the sample temperature is finely adjusted by the cooling control by the control device 23 described above.

Next, in order to perform the over-etching process of the second step following the first step, the discharge in the etching apparatus 1 is once cut off, and the gas remaining in the diffusion chamber 2 is exhausted from the exhaust port 13. Then, an etching gas used in the second step described later (in this embodiment, the same gas as that used in the first step is used) is introduced into the diffusion chamber 2, and this gas is stabilized to keep the inside of the diffusion chamber 2 constant. Adjust to the pressure of. In addition, during such a series of operations, that is, immediately after the etching process of the first step is completed, the electronic control valve 2 of the bypass pipe 21 in the cooling system by the chiller 17 is performed.
2, the electronic control valve 20 of the refrigerant pipe 15
Is fully opened to supply a gas refrigerant of −140 ° C. from the chiller 17 to the stage 12 to rapidly cool the sample W.

Then, due to such rapid cooling, the sample W reached an etching temperature of -30 ° C. described later in a short time of about 30 seconds. At this time, the series of operations described above, that is, the series of operations of discharging the residual gas in the diffusion chamber 2 after the discharge is cut off and introducing a new etching gas to stabilize the gas is more than the time required for rapid cooling. Or because it takes almost the same time,
The time required for this rapid cooling does not delay the time required for the etching process of the sample W.

Subsequently, the discharge is performed again, and the second step over-etching is performed at a low temperature (−30 ° C.) under the following conditions to expose the SiO ₂ film 32 as shown in FIG. 1C. A part of the remaining polysilicon layer 32 is removed by etching. Second step (over etching) etching gas; Cl ₂ / O ₂ 50/10 SCCM pressure; 5 mTorr source power 1 (RF antenna 4); 2500 W (1
3.56Hz) Source power 2 (RF antennas 3, 3); 2500W
(13.56 Hz) RF bias; 20 W sample temperature; -30 ° C

When the over-etching process is performed in this way, the etching process is performed under low-temperature cooling. Therefore, even if the formed sidewall protective film is thin, the radical reaction can be suppressed by lowering the temperature. Therefore, it becomes possible to withstand excessive radical attacks, and
Even if the applied bias to the sample is reduced to 100 W to 20 W as compared with the step, undercut and notching can be suppressed. Therefore, even under 100% over-etching, the selection ratio is 10 without affecting the shape.
It is possible to secure a sufficient anisotropic shape as shown in FIG. 1C while securing 0 or more.

In such a dry etching method, it is possible to achieve both a high selection ratio and an anisotropic shape, that is, high-precision microfabrication, and each step has the same etching apparatus 1. By doing so, the sample temperature can be easily changed between steps and in a short time, so it is possible to change the sample temperature within the time required for a series of operations such as stopping the discharge or changing the etching gas between steps. The temperature can be changed in a short time, and thus the dry etching process including a plurality of steps can be rapidly performed without lowering the throughput.

After the completion of the two-step etching process, if the same process is continuously repeated on a new sample with the same processing apparatus, the second step is completed and the post-process is completed. After taking out the sample, the stage 12 is adjusted to the sample set temperature in the first step, in this example, the first step, before introducing a new sample into the diffusion chamber 2. That is, in the first embodiment, the sample setting temperature was set to −30 ° C. in the second step, but the stage 12 was heated by the heater (not shown) of the electrostatic chuck, and the degree of cooling by the chiller 17 was performed. For example, in the cooling system using the chiller 17, the electronic control valve 22 of the bypass pipe 21 is fully opened, and the electronic control valve 20 of the refrigerant pipe 15 is fully closed, so that the chiller 1
The stage is rapidly heated by a method of stopping the supply of the gas refrigerant from 7 to the stage 12. Then, after the etching process of one sample is completed, it is possible to shorten the time until the etching process of a new sample is started, and in particular, during the time until the new sample is transported into the diffusion chamber 2, Alternatively, if the temperature can be changed to the stage 12 sample set temperature in a time close to this, the dry etching process including a plurality of steps can be performed without lowering the throughput, that is, in the state where sufficient productivity efficiency is secured.

Next, a second embodiment of the dry etching method of the present invention using the etching apparatus 1 shown in FIG. 4 will be described with reference to FIGS. 2 (a) to 2 (c). This processing method is an example in which the method of the present invention is applied to a method of processing a contact hole by etching. That is, this example, the photo this by the sample W forming a photoresist pattern 42 is formed on the SiO ₂ layer 41 on the silicon substrate 40 as shown in FIG. 2 (a), the SiO ₂ layer 41 was etched It is processed into a pattern shape corresponding to the resist pattern 42. Just etching (main etching) is performed at room temperature as the first step, and overetching at low temperature is performed as the second step.

First, just etching in the first step is performed under the following conditions, and SiO ₂ is removed as shown in FIG.
The layer 41 is removed by etching so that a part of the thin film remains. First step (just etching) Etching gas; C ₄ F ₈ / O ₂ 50/10 SCCM pressure; 5 mTorr Source power 1 (RF antenna 4); 2500 W (1
3.56Hz) Source power 2 (RF antennas 3, 3); 2500W
(13.56 Hz) Pulse ON / OFF; 10 μsec / 30 μsec RF bias; 500 W Sample temperature; 20 ° C. The sample temperature adjustment here is also provided on the stage 12 as in the case of the first embodiment. The heater (not shown) of the electrostatic chuck and the cooling by the chiller 17 are used together, and the sample temperature is finely adjusted by the cooling control by the control device 23 described above.

Next, in order to perform the over-etching process of the second step following the first step, the discharge in the etching apparatus 1 is once cut off, and the gas remaining in the diffusion chamber 2 is exhausted from the exhaust port 13. Then, an etching gas used in the second step described later (the same gas as in the first step is also used in this embodiment) is introduced into the diffusion chamber 2, and this gas is stabilized to keep the inside of the diffusion chamber 2 constant. Adjust to the pressure of. In addition, during such a series of operations, that is, immediately after the etching process of the first step is completed, the electronic control valve 2 of the bypass pipe 21 in the cooling system by the chiller 17 is performed.
2, the electronic control valve 20 of the refrigerant pipe 15
Is fully opened to supply a gas refrigerant of −140 ° C. from the chiller 17 to the stage 12 to rapidly cool the sample W.

Then, due to such rapid cooling, the sample W reached the below-mentioned etching temperature of -50 ° C. in a short time of about 30 seconds as in the case of the first embodiment. Therefore, even in this second embodiment,
Since a series of operations such as discharging the residual gas in the diffusion chamber 2 after the discharge is cut off and introducing a new etching gas to stabilize the same takes more than the time required for the rapid cooling, this rapid cooling is required. The time does not delay the time required for the etching process of the sample W.

Subsequently, the discharge is performed again, and the second step over-etching is performed at a low temperature (-50 ° C.) under the following conditions, leaving the silicon substrate 40 exposed as shown in FIG. 2 (c). A part of the SiO ₂ layer 41 is removed by etching to form a contact hole 43. Second step (overetch) etching gas; C ₄ F ₈ / O ₂ 50/10 SCCM pressure; 5 mTorr source power 1 (RF antenna 4); 2500 W (1
3.56Hz) Source power 2 (RF antennas 3, 3); 2500W
(13.56 Hz) Pulse ON / OFF; 10 μsec / 30 μsec RF bias; 200 W Sample temperature; −50 ° C.

When the over-etching process is performed in this manner, this etching process is performed under low temperature cooling. Therefore, even if the side wall protective film formed as in the case of the first embodiment is thin, the temperature is low. As a result, the radical reaction can be suppressed, and thus it becomes possible to withstand an excessive radical attack.
Even if the applied bias to the sample is lowered from 00 W to 200 W, undercut and notching can be suppressed. Therefore, for example, when the temperature is lowered from the just etching in the first step, the organic polymer is deposited on the side wall of the contact hole to be formed and the shape of the contact hole is tapered, which makes it impossible to form a fine hole. By lowering the temperature of only the over-etching as in the present embodiment, this problem is solved and a selection ratio of 100 or more with respect to the silicon substrate 40 is secured, while sufficient anisotropy is obtained as shown in FIG. 2C. The shaped contact hole 43 can be formed with good reproducibility. Therefore, even with such a dry etching method, it is possible to achieve both a high selection ratio and an anisotropic shape, that is, high-precision microfabrication, and a plurality of steps without lowering the throughput. Dry etching treatment consisting of

Even when the same processing is continuously repeated for a new sample after the completion of the two-step etching processing, the second sample is used as in the case of the previous example. After the step is completed and the processed sample is taken out, before the new sample is put into the diffusion chamber 2, the stage 12 should be adjusted to the sample set temperature in the first step, in this example, the first step. The dry etching process including a plurality of steps can be performed in a state where sufficient productivity efficiency is secured without lowering the throughput.

Next, a third embodiment of the dry etching method of the present invention will be described with reference to FIGS. 3 (a) to 3 (c). This processing method is an example in which the method of the present invention is applied to a method of processing polysilicon on a SiO ₂ layer having a high step. That is, in this example, as shown in FIG. 3A, a polysilicon layer 51 is formed on a SiO ₂ layer 50 having a high step formed on a silicon substrate (not shown), and a photoresist is formed thereon. The polysilicon layer 51 of the sample W on which the pattern 52 is formed is etched and processed into a pattern shape corresponding to the photoresist pattern 52. As a first step, main etching at a low temperature is performed, and as a subsequent second step. Overetching is performed at a high temperature. In this embodiment, as the etching apparatus, the cooling means and its control mechanism in the etching apparatus 1 shown in FIG. 4, that is, the refrigerant pipes 15, 16, the chiller 17, the fluorescent fiber thermometer 1 are used.
EC equipped with 8, control device, electronically controlled valves 20, 22, bypass pipe 21, control device 23, and stage 12
An R type etcher (not shown) is used.

First, the main etching of the first step is performed under the following conditions, and the polysilicon layer 51 is removed by etching as shown in FIG. First step 1 (main etching) etching gas; Cl ₂ / O ₂ 90/10 SCCM pressure; 10 mTorr μ wave power; 850 W RF bias; 100 W sample temperature; -30 ° C. Since the etching is performed at a low temperature of -30 [deg.] C., a strong sidewall protective film is formed on the etching pattern 51a formed of the polysilicon layer 51. At this time, in the step portion 50a of the SiO ₂ layer 50, since the polysilicon layer 51 formed here is thicker than the other portions, the stringer (etch residue) 53 that is not removed by etching is formed. It is formed.

Regarding the sample temperature adjustment here,
This is performed in the same manner as the temperature adjustment in the second step in the case of the first and second embodiments. Next, in order to perform the overetching process of the second step following the first step, the control mechanism of the cooling means and the stage 1 described above are used.
The heater provided in 2 is adjusted to rapidly heat the sample W. Then, by such rapid heating, the sample W has an etching temperature of 5 which will be described later in a short time of about 50 seconds.
Reached 0 ° C. Therefore, even in the third embodiment, the time required for this rapid heating does not become a factor that delays the time required for the etching process of the sample W.

Subsequently, the discharge is performed again, and the second step overetching is performed at a high temperature (50 ° C.) under the following conditions to form a step portion 50a of the SiO ₂ layer 50 as shown in FIG. 3C. Stringer (remaining etch) 53
Is removed. Second step (overetching) Etching gas; Cl ₂ 100 SCCM pressure; 10 mTorr μ wave power; 850 W RF bias; 50 W Sample temperature; 50 ° C. When such over-etching treatment is performed, the sample temperature becomes high (50 ° C.). Since the radical reaction is promoted by doing so, the stringer 53 formed on the step portion 50a can be easily removed. Further, at this time, since the etching pattern 51a is formed by the low temperature etching in the first step to form a strong sidewall protection film on its sidewall, the shape thereof is not affected by this overetching.

Therefore, even in this dry etching method, as in the first and second embodiments, both a high selection ratio and an anisotropic shape can be ensured, that is, high-precision micromachining can be achieved. Moreover, the dry etching process including a plurality of steps can be performed without lowering the throughput. Even when the same process is continuously repeated for a new sample after the completion of the two-step etching process, the second step is completed as in the case of the previous example. After removing the processed sample, the throughput will be reduced if the stage is adjusted to the sample set temperature in the first step, in this example the first step, before inserting a new sample into the chamber. Instead, the dry etching process including a plurality of steps can be performed while ensuring sufficient productivity efficiency.

Further, in the above-mentioned embodiment, the etching process is composed of two steps, but the present invention is not limited to this, and the etching process may be carried out in three or more steps. Further, the first embodiment example, the second embodiment
When the first step is the main etching or the just etching performed at room temperature and the second step subsequent to this is the over-etching performed at the low temperature as in the embodiment, the same processing apparatus is installed between these steps. The sample after the first step may be subjected to O ₂ plasma treatment or N ₂ plasma treatment. When such a plasma treatment is performed, the side wall of the etching pattern of the sample is oxidized or nitrided, and a strong oxide or nitride is formed on this side wall portion. It is possible to prevent the etching pattern from being excessively etched, and thus the shape of the finally obtained etching pattern to be largely different from the desired shape, and to secure the anisotropic shape more reliably. it can.

[0037]

As described above, the dry etching method according to the first aspect of the present invention changes the sample temperature between the etching processing in one step and the etching processing in the subsequent step. If the main etching process is performed at room temperature as one step and the overetching process is performed at a low temperature as a subsequent step, even if the side wall protective film to be formed is thin, the temperature is lowered by the low temperature during the overetching process. Since the radical reaction can be suppressed as described above, it becomes possible to withstand the excessive radical attack that occurs. Therefore, due to the effect of suppressing the radical reaction due to this low temperature,
Even if the bias applied to the sample is lowered, it is possible to prevent undercut and notching, and thus it is possible to achieve both a high selection ratio and an anisotropic shape, that is, high-precision micromachining. . Further, since each etching process is performed in the same processing apparatus, the time required for changing the sample temperature between steps can be shortened. Therefore, if the time required for changing the sample temperature is set within the time required for a series of operations such as stopping the discharge between steps or changing the etching gas, or if the temperature is changed within a time close to this, the throughput can be improved. It is possible to perform a dry etching process including a plurality of steps without decreasing the temperature.

According to the dry etching method of the fourth aspect, since the etching processing of the first step and the etching processing of the final step are performed at different temperatures, the same effect as that of the invention of the first aspect is provided. Can be obtained. Furthermore, after the etching process of the final step is completed, before the next sample is put in the same processing apparatus, the temperature of the sample stage is changed to the sample set temperature in the etching process of the first step.
After the etching process of one sample is completed, the time until the etching process of the next sample is started can be shortened, which can improve the productivity.

[Brief description of drawings]

1A to 1C are side sectional views of main parts for explaining a first embodiment example of a dry etching method of the present invention in the order of processing.

2A to 2C are side cross-sectional views of a main part for explaining a second embodiment of the dry etching method of the present invention in the order of processing.

3 (a) to 3 (c) are side cross-sectional views for explaining a third embodiment of the dry etching method of the present invention in the order of processing.

FIG. 4 is a schematic configuration diagram of an etching apparatus suitable for carrying out the method of the present invention.

[Explanation of symbols]

1 Plasma Etching Device 12 Stage (Sample Stand) 30, 40 Silicon Substrate 31 SiO ₂ Film 3
2 polysilicon film 33 WSi _x layer 34, 42, 52 photoresist pattern 41, 50 SiO ₂ layer 43 contact hole 51 polysilicon layer W sample

Claims (4)

[Claims] 1. A dry etching method for performing an etching process of a plurality of steps on a sample in the same processing apparatus, wherein an etching process of one of the steps and an etching of a subsequent step. During the treatment, the temperature of the sample is changed to perform the etching treatment at different temperatures in the one step and the subsequent step. 2. One of the steps is a main etching process for keeping the sample temperature at room temperature, and an etching process for the subsequent steps is an over-etching process for keeping the sample temperature at a low temperature. The dry etching method according to claim 1. 3. The sample after the main etching treatment is treated with O ₂ plasma or N ₂ plasma in the same treatment apparatus between the main etching treatment of the one step and the over etching treatment of the subsequent step. The dry etching treatment method according to claim 2, wherein the dry etching treatment is performed. 4. A dry etching treatment method in which an etching treatment consisting of a plurality of steps is repeatedly performed on a plurality of samples in the same treatment apparatus, wherein an etching treatment of a first step among the steps is performed. The temperature of the sample is changed by changing the temperature of the sample stage supporting the sample during the etching process of the final step, and the etching process of different temperatures is performed in the first step and the final step, and When the etching process of the final step is completed, before the next sample is put into the processing apparatus, the sample set temperature in the etching process of the first step is set to
A dry etching method, wherein the temperature of the sample stage is changed.