JPH1064886A - Device and method for dry etching - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately control a form at etching by controlling the amount of product, which is generated from an aperture provided to a chamber, accumulated on a sample body by plasma. SOLUTION: With a dry etching device 1, plasma is generated in a chamber 10 provided with, for example, a quartz aperture 14 comprising silicon oxide system material, and a wafer 40, placed in the chamber 10 as a sample body is etched. In this case, an auxiliary electrode 15 which is provided near the wafer 40 placed in the chamber 10 to accumulate a product generated from the aperture by plasma, and a film thickness measuring means 16 which is provided to the chamber 10 to measure a thickness of the material accumulated on the auxiliary electrode 15, are provided. In addition, a feedback means 20 which, based on the thickness of the accumulated material which has been measured with the film thickness measuring means 16, adjusts a thickness of the material to be accumulated thereafter is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry etching apparatus and a dry etching method.

[0002]

2. Description of the Related Art With the progress of high integration of ULSI, the demand for fine processing technology is becoming more and more severe. In the dry etching process, the demand is no exception, and various developments are being pursued with the aim of high-precision processing. In particular, in an etching process for processing a gate electrode, very strict dimensional control is required along with a high selectivity. Therefore, in this etching step, an etching apparatus using chlorine (Cl) or bromine (Br) as a main radical, which uses a high-density plasma source and provides a high selectivity, has been generally used. I have.

One example of a conventional etching apparatus using a high-density plasma source is, for example, an ICP (Inductively Coupled).
d Plasma) type etching apparatus will be described as an example.
This apparatus has a chamber, and a window made of quartz as a dielectric material (hereinafter, referred to as a quartz window) is provided on a side wall of the chamber. The chamber forms an atmosphere for etching a wafer to be etched. Outside the quartz window, an electric field source including, for example, a coil (antenna) and an electrode is provided, and an RF power supply for supplying high frequency (RF) power to the electric field source is connected.

[0004] Such an etching apparatus uses an RF electric field source through a quartz window in a chamber at a low pressure.
When an electric field is provided, the RF electric field is coupled into the plasma to create a dense plasma. The high-density plasma processes a wafer placed in the chamber with a high selectivity and a high etching rate. Note that other etching apparatuses using a high-density plasma source, for example, ECR (Electron Cycrotron®)
Esonance) etching equipment, helicon plasma etching equipment, MCR (Magnetically Confined Reactor) etching equipment, etc. are all supplied with an electric field from an electric field supply source installed near a quartz window.

[0005]

In a conventional etching apparatus using a high-density plasma source, a high-energy ion is incident on the surface of a quartz window by a DC electric field generated near an electric field supply source, and the window is sputtered. Is done. And the product generated from the quartz window by sputtering affects the performance of the etching process,
It has been clarified by the study of the inventors.

For example, when an ICP type etching apparatus is used to etch a wafer in which a polysilicon (Poly-Si) film is formed on a silicon substrate by chlorine plasma to form a Poly-Si electrode pattern. When the RF power supplied to the electric field supply source is large, chlorine ions are accelerated by the sheath electric field generated near the electric field supply source and enter the quartz window. The chemical reaction promoted by the ion bombardment causes silicon oxide chloride (SiO 2).
_x Cl _y) and the product such as oxygen (O) is generated from the quartz window.

[0007] Of these products, those having a low vapor pressure adhere to and deposit on the side walls of the Poly-Si electrode pattern 73 as shown in FIG. For example, a sidewall protective film 75 is formed with SiCl _x ). As a result, the Poly-Si electrode pattern 73 has a so-called forward tapered shape, and the Poly-Si electrode pattern 7
3 is detected as a dimensional conversion difference in the direction of increasing the thickness. In FIG. 8, reference numeral 71 denotes a silicon substrate, 72 denotes a silicon oxide film, and 74 denotes an etching mask made of resist.

In order to prevent such excessive deposition, at present, countermeasures have been taken to use a relatively high substrate temperature and to lower the probability of the above products adhering. However, the high temperature of the substrate temperature, for example in the case of etching tungsten silicide (WSi _x) to promote the formation of chloride higher tungsten oxide vapor pressure (WOCl _x), also promotes the radical reaction, such as a notch . When the generation of WOCl _x is promoted, excess oxygen radicals are generated from this, and etching proceeds isotropically by the generated oxygen radicals. Therefore, raising the substrate temperature is not a good idea.

Here, the sum of the amount of the product from the quartz window incident on the wafer and the amount of the reaction product generated from the wafer re-entering the wafer determines the etching characteristics of the sidewall protective film and the like. Conceivable. That is, the sum of these is considered to determine the optimum deposit amount during the process. Therefore, there is a need for an etching technique capable of monitoring and controlling the amount of the deposit itself, which is formed by the product from the quartz window incident on the wafer. If the amount of the deposit cannot be sufficiently controlled, the forward taper as shown in FIG. 8A due to the above-mentioned excessive deposit and the FIG. 8B due to the lack of the deposit at the time of over-etching are shown in FIG. Abnormal shape such as reverse taper is observed.

[0010]

A dry etching apparatus according to the present invention for solving the above-mentioned problem generates plasma in a chamber having a window made of a silicon oxide-based material, and forms a plasma in the chamber. An etching body for etching an etching body, provided near a body to be etched placed in a chamber, provided with an auxiliary electrode for depositing a product generated from the window by plasma, and provided in the chamber. And a film thickness measuring means for measuring the thickness of the deposit deposited on the auxiliary electrode. Further, it is provided with feedback means for adjusting the thickness of the deposit to be subsequently deposited based on the thickness of the deposit measured by the film thickness measuring means.

A dry etching method according to the present invention for solving the above-mentioned problems is a method of generating plasma in a chamber having a window made of a silicon oxide-based material and etching an object to be etched placed in the chamber. The thickness of a deposit formed by depositing a product generated from the window by the plasma on the body to be etched by the plasma, and then depositing the deposit based on the measured thickness of the deposit This is a method of adjusting the thickness of the deposit.

In the dry etching apparatus according to the present invention,
Since the auxiliary electrode is provided near the object to be etched placed in the chamber, the product generated from the window by the plasma is also incident on the object to be etched and deposited on the auxiliary electrode from the window in almost the same manner. Are deposited.
In addition, since there is provided a film thickness measuring means for measuring the thickness of the deposit deposited on the auxiliary electrode, the amount of change in the thickness of the deposit when the product from the window is deposited on the etching target is indirectly measured. Is measured. Further, in the configuration including the feedback unit, the thickness of the deposit from the subsequently deposited window is adjusted based on the thickness of the deposit from the film thickness measuring unit. The amount of the deposit, which is the sum of the reaction product re-entering the object to be etched and the product from the window depositing on the object to be etched, is adjusted.

In the dry etching method according to the present invention,
The product generated from the window measures the thickness of the deposit when deposited on the object to be etched, and adjusts the thickness of the subsequent deposit based on the obtained thickness of the deposit. It is possible to control the amount of the deposit, which is the sum of the reaction product generated from the body to be re-incident on the body to be etched and the product from the window to be deposited on the body to be etched, to an optimal amount. Will be possible.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a dry etching apparatus according to the present invention will be described with reference to FIG. Here, a case where the apparatus of the present invention is applied to an IPC type etching apparatus will be described. As shown in FIG. 1, the dry etching apparatus 1 includes a chamber 10 for generating high-density plasma to form an etching atmosphere. In the chamber 10, there is provided a stage 11 on which an object to be etched, for example, a wafer 40 is placed.
The stage 11 also serves as a lower electrode, and is connected to the RF bias power supply 12. This RF bias power supply 12
Is composed of, for example, a 400 kHz high frequency power supply.
A grounded ground electrode 13 is provided above the stage 11 and above the chamber 10.

A quartz window 14 made of quartz, which is a kind of silicon oxide-based material, is provided on the side of the stage 11 and on the side wall of the chamber 10. An auxiliary electrode 15 is provided near the wafer 40 mounted on the stage 11. The auxiliary electrode 15 is for depositing a product generated by sputtering the quartz window 14 by plasma generated in the chamber 10. That is, it monitors the amount of the product from the quartz window 14 incident on the wafer 40 on the stage 11 and deposited.

The auxiliary electrode 15 has, for example, a substantially rectangular shape.
And a size of about 1 cm square. Ma
In addition, the thickness of the deposit deposited on the auxiliary electrode 15 can be measured.
It is formed of a material that can be used. As described below, this implementation
In the embodiment, the thickness of the deposit deposited on the auxiliary electrode 15 is measured.
An optical film thickness meter is used for the means 16. Therefore, the auxiliary electrode 1
5 is a material that reflects light from the thickness gauge, for example, silicon
(Si) SiO on the substrate _TwoA film was formed with a thickness of about 300 nm.
It is formed of things. The auxiliary electrode 15 is
The surface on which the load is to be deposited is placed on the wafer placed on the stage 14.
C) Deposits are deposited substantially flush with the surface 40
With the surface facing the same direction as the etched surface of the wafer 40
In this state, it is provided near the wafer 40.

Further, the auxiliary electrode 15 is set at a floating potential when the wafer 40 is etched. When necessary, for example, when cleaning the auxiliary electrode 15, the wafer 4 placed on the stage 11 is changed from the floating potential.
It can be switched to the same potential as 0 (RF bias). When the auxiliary electrode 15 is set to the floating potential during the etching process of the wafer 40, when the same potential as that of the wafer 40 is applied to the auxiliary electrode 15, the auxiliary electrode 15 is also sputtered by plasma and deposited on the auxiliary electrode 15. This is because an accurate change in the film thickness of the deposit cannot be grasped.

Above the chamber 10 and above the auxiliary electrode 15, a film thickness measuring means 1 for measuring the thickness of the deposit deposited on the auxiliary electrode 15 in a so-called in-situ manner.
6 are provided. As the film thickness measuring means 16, for example, a non-contact type which does not affect the etching process can be used. Further, among the products from the quartz window 14, those that contribute to the deposition are SiO _x -based products, and these can be easily measured by an optical film thickness meter. Therefore, in this embodiment, as the non-contact type film thickness measuring means 16, an optical film thickness meter that obtains the thickness of the deposit by the change of the interference waveform of the laser light incident on the auxiliary electrode 15 is used. This optical film thickness meter measures the film thickness based on the same principle as that of an optical film thickness meter used in a normal wafer process, and reflects the reflected light on the Si substrate and the reflected light on the deposit surface. Is used to calculate the thickness of the deposit.

The film thickness measuring means 16 is not limited to an optical film thickness meter, and can be installed in the chamber 10 without affecting the etching process. Any one can be used as long as it can be measured.

An electric field supply source 17 is provided outside the chamber 10 and at the position of the quartz window 14. The electric field supply source 17 supplies an electric field for generating plasma into the chamber 10. For example, a coil-shaped antenna or a plate-shaped antenna is provided to supply an RF electric field of, for example, 13.56 MHz to the inside of the chamber 10 to be coupled thereto. This electric field supply source 17 includes:
For example, a source power supply 18 composed of a 13.56 MHz high frequency power supply is connected.

The chamber 10 has gas supply means (not shown) for supplying an etching gas into the chamber.
Gas exhaust means (not shown) for keeping the internal pressure of the chamber 10 constant is provided. Further chamber 10
Is provided with end point detecting means 19 (see FIG. 2) for detecting the end point of the main etching. Here, the main etching is etching for processing the layer to be etched until the surface of the substrate is exposed when the wafer 40 has the layer to be etched formed on the substrate.

The dry etching apparatus 1 then uses the wafer 40 and the auxiliary electrode 1 on the stage 11 based on the thickness of the deposit measured by the film thickness measuring means 16 described above.
5 is provided with feedback means 20 for adjusting the thickness of the deposit from the quartz window 14. The feedback means 20 is composed of, for example, a personal computer. For example, as shown in FIG.
And a display unit 2 connected to the main body 23
4, and an input unit 25. The feedback means 20 includes the film thickness measuring means 16 and the source power supply 1
8 and the end point detecting means 19.

The memory 22 stores the amount of electric power supplied from the source power supply 18 to the electric field supply source 17 and the amount of change in the thickness of the deposit deposited on the auxiliary electrode 15, for example, the temporal change in the thickness of the deposit. The data of the correlation with the deposition rate obtained by the inclination is stored. This relationship is obtained in advance by an experiment and stored in the memory 22. Control unit 21
Is to output a signal to the source power supply 18 to change the electric energy based on the data of the thickness of the deposit measured by the film thickness measuring means 16. For example, when the data of the thickness of the deposit is sent from the film thickness measuring means 16, the control unit 21 obtains the deposition rate based on the temporal change as shown in FIG.
The amount of power supplied from the source power supply 18 is changed using the determined deposition rate and the data stored in the memory 22.

The display unit 24 displays, for example, data of the thickness of the deposit measured by the film thickness measuring means 16, data of the deposition rate obtained by the control unit 21, data stored in the memory 22, and the like. Things. The input unit 25 inputs the set deposition rate of the deposit deposited on the auxiliary electrode 15 when the wafer 40 is etched (the set value of the deposition rate when the product from the quartz window 14 is deposited on the wafer 40). , For example, a keyboard.

In the feedback means 20 having the above-described structure, conditions set in advance for performing the etching process, such as the deposition rate when the product generated from the quartz window 14 is deposited on the wafer 40, are used. The condition is input from the input unit 25 to the control unit 21. For example, when performing an etching process of over-etching after the main etching of the wafer 40, the set deposition rate is input at each of the main etching and the over-etching as shown in FIG. At this time, the respective set deposition rates are input under such a condition that the deposition rate during over-etching is higher than the deposition rate during main etching.

When the etching of the wafer 40 is started and the data of the thickness of the deposit is sent from the film thickness measuring means 16 to the control unit 21, the control unit 21 obtains the deposition rate from the sent data. Then, the amount of power supplied from the source power supply 18 is adjusted using the data stored in the memory 22 so that the obtained deposition rate becomes the above-described set deposition rate. Further, when the end point detection signal of the main etching is sent from the end point detection means 19, the control unit 21 adjusts the amount of power of the source power supply 18 so that the deposition rate at the time of over-etching is achieved.

In the dry etching apparatus 1, a plasma is generated in the chamber 10 by the RF electric field from the electric field supply source 17. In addition, a sheath electric field is generated near the electric field supply source 17, and high-energy ions in the plasma enter the quartz window 14 by the electric field to generate a product. The product from the quartz window 14 is
And the reaction products generated from the wafer 40 by the plasma re-enter the wafer 40 to form a deposit such as a sidewall protective film.

As described above, in the dry etching apparatus 1, since the auxiliary electrode 15 is provided near the wafer 40 placed in the chamber 10, the product generated from the quartz window 14 by the plasma enters the wafer 40. Similar to the deposition, the product from the quartz window 14 can be deposited on the auxiliary electrode 15. The auxiliary electrode 15
Thickness measuring means 16 for measuring the thickness of the deposits deposited on
, It is possible to indirectly measure the deposition rate when the product generated from the quartz window 14 is deposited on the wafer 40. Further, since the auxiliary electrode 15 has a floating potential, the deposition on the auxiliary electrode 15 is not sputtered by plasma, and the deposition rate can be accurately grasped.

Further, in the dry etching apparatus 1, the amount of power supplied from the source power supply 18 is changed by the feedback means 20 based on the measured value of the thickness of the deposit measured by the film thickness measuring means 16, and thereafter, The amount of the product generated from the quartz window 14 is adjusted.
Therefore, the amount of the deposit, which is the sum of the reaction product generated from the wafer 40 re-incident on the wafer 40 and the product deposited from the quartz window 14 on the wafer 40, is adjusted to the optimum amount. can do. This adjustment can be made automatically. In addition, the amount of power supplied from the source power supply 18 is one of the factors that greatly change the deposition rate, and therefore, the amount of deposit can be adjusted with good controllability. Therefore, according to the dry etching apparatus 1, a dimensional conversion difference generated due to excess or insufficient deposits can be accurately controlled, so that a stable etching process with a small dimensional conversion difference can be realized. .

The deposits deposited on the auxiliary electrode 15 of the dry etching apparatus 1 are easily generated by generating a halogen plasma (Cl ₂ , SF _6, etc.) while applying an RF bias and exposing it to the halogen plasma. Can be removed.

Next, a first embodiment of the dry etching method according to the present invention will be described. This dry etching method is a method in which plasma is generated in a chamber having a window made of a silicon oxide-based material, and an object to be etched, such as a wafer, placed in the chamber is etched. First, the product generated from the window by the plasma impinges on the wafer and deposits the thickness of the deposit in
Measure in situ (first step). Next, the thickness of the deposit to be subsequently deposited on the wafer is adjusted based on the measured deposited film thickness (second step).

The thickness of the deposit in the second step is adjusted when the plasma is generated by an RF electric field from an electric field supply source provided outside the chamber. This is done by changing the amount of power to be applied. In the case where overetching is performed after the main etching of the wafer on which the layer to be etched is formed on the substrate, the thickness of the deposit is adjusted in the second step, for example, as follows. That is, as shown in FIG. 3, the electric power is set so that the amount of change in the thickness of the deposit, for example, the deposition rate obtained from the slope of the temporal change in the thickness becomes constant during main etching and overetching, respectively. The amount is varied and the thickness of the subsequently deposited deposit is adjusted. Further, the amount of power is changed so that the deposition rate at the time of over-etching becomes larger than the deposition rate at the time of main etching in the direction of increasing the thickness of the deposit deposited on the wafer.

The window is a quartz window for passing an RF electric field from an electric field supply source into the chamber, and when plasma is generated in the chamber when the etching gas is a halogen gas, a halogen ion is located near the quartz window. Sheath acceleration occurs. Then, from the quartz window, SiO _x X _y (X = Cl,
(E.g., Br). In the above method, when the product generated from the quartz window is deposited on the wafer, the thickness is measured, and the thickness of the subsequent deposit is adjusted based on the obtained measurement value. It is possible to adjust the amount of the deposit, which is the sum of the product in which the reaction product re-enters the wafer and the product in which the product from the quartz window is deposited on the wafer, to the optimal amount. At this time, the amount of electric power supplied to the electric field supply source, which is one of the factors that greatly change the deposition rate of the deposit, is changed, so that the amount of the deposit can be adjusted with good controllability.

Further, since the thickness of the deposit is adjusted so that the deposition rate is constant during the main etching and the over-etching, the processed pattern has a forward tapered shape or a reverse tapered shape. The occurrence of an abnormality can be prevented. Further, the deposition rate at the time of over-etching is made larger in the direction of increasing the thickness of the deposits deposited on the wafer than the deposition rate at the time of the main etching. , Prevents the occurrence of reverse taper,
The pattern can be processed into a good anisotropic shape.

In the main etching in which strict dimensional control is required, the amount of silicon oxide-based deposits deposited on the wafer can be reduced, and the deposits can be prevented from becoming excessive. Therefore, according to the above-mentioned dry etching method, it is possible to perform an etching process with a small dimensional conversion difference and an over-etching resistance, so that a pattern with high dimensional accuracy can be formed.

Next, an example of processing a wafer by the above-described dry etching method using the above-described dry etching apparatus 1 will be described. As shown in FIG. 4A, a wafer 40 to be processed here is formed on a Si substrate 41 serving as a base.
After forming a gate oxide film 42 of iO ₂ , a Poly-Si film 43 is formed thereon, and a resist mask 44 is further formed. Then, this wafer 40
Was processed into a gate electrode pattern by main etching and over-etching under the following conditions using the resist mask 44 as an etching mask.

As an example of the main etching conditions, an etching gas and its flow rate: chlorine (Cl ₂ ) / 10
0 sccm [sccm represents a volume flow rate (cm ³ / min) in a standard state] Etching atmosphere pressure: 0.5 Pa RF bias: 80 W Substrate temperature: 30 ° C. Deposition rate: 2 nm / min An example of the over-etching condition is an etching gas and its flow rate: chlorine (Cl ₂ ) / 10.
0 sccm Etching atmosphere pressure: 0.5 Pa RF bias: 30 W Substrate temperature: 30 ° C. Deposition rate: 10 nm / min.

As described above, in the main etching, in which the dimensions of the gate electrode are determined, the amount of deposits is small in order to suppress the generation of the forward taper, and in the over etching, the amount of deposits is large in order to suppress the occurrence of the notch and the reverse taper. The deposition rate during main etching was set to 2 nm / min, and the deposition rate during overetching was set to 10 nm / min. Then, the source power supply 1 for each etching
As a result of feedback control of the power amount from No. 8, the power amount was adjusted to 200 W during the main etching and to 1 kW during the over-etching. As a result, FIG.
(B) As shown in FIG.
An i-electrode pattern 45 was obtained. As is clear from these results, according to the dry etching apparatus 1 and the dry etching method of the above embodiment, it is possible to achieve a processing process in which a dimensional conversion difference is small and overetching resistance is obtained.

Next, a dry etching apparatus according to a second embodiment of the present invention will be described with reference to FIG. Here, a case in which the apparatus of the present invention is applied to an MCR type etching apparatus will be described. The same components as those in the first embodiment described with reference to FIG. As shown in FIG.
Differs from the dry etching apparatus 1 shown in FIG. 1 in the configuration near the electric field supply source 31.

That is, the electric field supply source 31 is
0 is provided outside through a quartz window 14. The electric field supply source 31 is composed of an annular electrode, and a magnetic field generator 32 for forming a magnetic field is provided on the outer periphery thereof. The magnetic field generator 32 is formed of, for example, a permanent magnet. The magnetic field generator 32 only needs to generate a magnetic field, and may be formed by, for example, an electromagnet. The electric field supply source 32 is connected to a source power supply 18 composed of, for example, a 13.56 MHz high frequency power supply.

In the dry etching apparatus 3, similarly to the dry etching apparatus 1, an auxiliary electrode 15 is provided near the wafer 40 mounted on the stage 11. In this auxiliary electrode 15, the surface on which the deposit is deposited faces in the same direction as the etched surface of the wafer 40. A film thickness measuring means 1 for measuring the thickness of the deposit deposited on the auxiliary electrode 15 in a so-called in-situ manner above the chamber 10 and above the auxiliary electrode 15.
6 are provided. The film thickness measuring means 16 comprises, for example, an optical film thickness meter. Further, the dry etching apparatus 3 is provided with a feedback means 20, and the above-mentioned film thickness measuring means 1 is provided.
Based on the thickness of the deposit measured by 6, the thickness of the deposit subsequently deposited on the wafer 40 and the auxiliary electrode 15 on the stage 11 is adjusted.

In the above dry etching apparatus 3, 13.56 MH is supplied to the electric field supply source 31 by the source power supply 18.
A high frequency of z is applied, electrons are accelerated by the interaction between the magnetic field and the electric field by the magnetic field generator 32, and high-density plasma is generated in the chamber 10. Then, the wafer 40 is etched by the generated plasma. Here, since the auxiliary electrode 15 is provided in the vicinity of the wafer 40, the situation in which the product generated from the quartz window 14 is incident on the wafer 40 and deposited by the plasma can be monitored by the auxiliary electrode 15. . In addition, film thickness measuring means 1
6, the deposition rate can be measured, whereby the deposition rate of the product from the quartz window 14 on the wafer 40 can be ascertained.

Further, by the feedback means 20,
Based on the measured value from the film thickness measuring means 16, the source power supply 1
8 is feedback-controlled to adjust the thickness of the subsequent deposit, so that the reaction product generated from the wafer 40 is re-incident on the wafer 40 and the product from the quartz window 14 Can be adjusted to an optimum amount. This adjustment can be made automatically. Accordingly, the dimensional conversion difference can be accurately controlled by the dry etching apparatus 3 as well, and a stable etching process with a small dimensional conversion difference can be realized.

Next, an example of processing the wafer 40 shown in FIG. 4A by the above-described dry etching method of the first embodiment using the dry etching apparatus 3 will be described. That is, in this processing, the wafer 40 was processed into a gate electrode pattern by main etching and over-etching set under the following conditions. An example of the main etching conditions is an etching gas and its flow rate: chlorine (Cl ₂ ) / 10.
0 sccm Etching atmosphere pressure: 0.5 Pa RF bias: 70 W Substrate temperature: 50 ° C. Deposition rate: 1 nm / min. An example of the over-etching condition is an etching gas and its flow rate: chlorine (Cl ₂ ) / 10.
0 sccm Etching pressure: 0.5 Pa RF bias: 30 W Substrate temperature: 50 ° C. Deposition rate: 15 nm / min

As described above, the deposition rate in the main etching is set to 1 nm / min, and the deposition rate in the over etching is set so that the deposit is small in the main etching which determines the dimensions of the gate electrode and large in the over etching. It was set to 15 nm / min. Then, as a result of feedback control of the amount of power supplied from the source power supply 18 during each etching, the power amount was adjusted to 200 W during the main etching and to 1.2 kW during the over-etching. As a result, even in this case, as shown in FIG.
A Poly-Si electrode pattern 45 was obtained. Therefore, according to the dry etching apparatus 3 and the dry etching method of the above embodiment, it was confirmed that the shape can be accurately controlled at the time of etching, and a pattern with high dimensional accuracy can be obtained.

Next, a dry etching apparatus according to a third embodiment of the present invention will be described with reference to FIG. Here, a case where the apparatus of the present invention is applied to an IPC type etching apparatus will be described. The same components as those in the first embodiment described with reference to FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. As shown in FIG. 6, this dry etching apparatus 5
The dry etching apparatus 1 shown in FIG. 1 includes a distance changing unit 52 for changing the relative distance between the electric field supply source 51 and the quartz window 14, and the feedback unit 20 controls the distance changing unit 52. The difference is that they are designed to be used.

That is, an electric field supply source 51 is provided at a predetermined distance outside the quartz window 14 provided on the side of the stage 11 and on the side wall of the chamber 10. The electric field supply source 51 includes, for example, a coil-shaped antenna or a plate-shaped antenna, and supplies an RF electric field of 13.56 MHz, for example, coupled to the inside of the chamber 10. The electric field supply source 51 includes, for example, 1
A source power supply 18 composed of a 3.56 MHz high frequency power supply is connected.

The electric field supply source 51 is provided with a distance changing section 52 which makes it movable in the direction of the arrow in the drawing and changes the relative distance between the electric field supply source 51 and the quartz window 14. The distance changing unit 52 includes, for example, a support 53 that supports the electric field supply source 51 and a main body 54 that moves the support 53.
It is composed of The main body 54 may have any configuration as long as the support 53 can be moved. For example, the main body 54 moves the support body 53 in the direction of the arrow by driving a motor (not shown).

In the dry etching apparatus 5, similarly to the above-described dry etching apparatus 1, an auxiliary electrode 15 is provided near a wafer 40 mounted on the stage 11. In addition, the upper part of the chamber 10 and the auxiliary electrode 15
A film thickness measuring means 16 for measuring the thickness of the deposit deposited on the auxiliary electrode 15 in a so-called in-situ manner is provided at a position above the auxiliary electrode 15. The film thickness measuring means 16 comprises, for example, an optical film thickness meter.

The feedback means 20 is based on the thickness of the deposit measured by the film thickness measuring means 16, and then deposits on the wafer 40 and the auxiliary electrode 15 on the stage 11 from the quartz window 14. The thickness is adjusted. As shown in FIG. 2, the feedback unit 20 includes a main body 23 including a memory 22 and a control unit 23, a display unit 24, and the like, as shown in FIG.
An input unit 25 is provided. Further, the feedback unit 20 is connected to the film thickness measuring unit 16, the distance changing unit 52, and the end point detecting unit (not shown).

In this embodiment, the memory 22 stores the relative distance between the electric field supply source 51 and the quartz window 14 and the amount of change in the thickness of the deposit deposited on the auxiliary electrode 15, for example, the time of the thickness. The data of the correlation with the deposition rate obtained by the gradient of the target change is stored. This relationship is
It is determined in advance by an experiment and stored in the memory 22.
The control unit 21 outputs a signal to the distance changing unit 52 to change the relative distance between the electric field supply source 51 and the quartz window 14 based on the data on the thickness of the deposit measured by the film thickness measuring unit 16. Things. For example, when the data of the thickness of the deposit is sent from the film thickness measuring means 16, the control unit 21 obtains the deposition rate from the temporal change of the thickness of the deposit, and stores the obtained deposition rate and the memory 22. The relative distance between the electric field supply source 51 and the quartz window 14 is changed using the data. The display unit 24 and the input unit 25 are connected to the feedback unit 20 of the dry etching apparatus 1 described above.
It has the same function as those of.

In the feedback means 20 configured as described above, the conditions set in advance for performing the etching process, that is, the products from the quartz window 14
Conditions such as the deposition rate when the deposition is performed on zero are input from the input unit 25 to the control unit 21. For example, when performing an etching process of over-etching after the main etching of the wafer 40, the set deposition rate is input at each of the main etching and the over-etching. At this time, the respective set deposition rates are input under such a condition that the deposition rate during over-etching is higher than the deposition rate during main etching.

When the etching of the wafer 40 is started and the data of the thickness of the deposit is sent from the film thickness measuring means 16 to the control unit 21, the control unit 21 obtains the deposition rate from the sent data. Then, the relative distance between the electric field supply source 51 and the quartz window 14 is adjusted using the data stored in the memory 22 so that the determined deposition rate becomes the above-described set deposition rate. When the end point detection signal of the main etching is sent from the end point detection means, the control unit 21 adjusts the relative distance between the electric field supply source 51 and the quartz window 14 so that the deposition rate at the time of over-etching is achieved.

In the dry etching apparatus 5, since the distance changing section 52 is provided, the distance between the electric field supply source 51 and the quartz window 14 can be changed. Therefore, the energy of ions incident on the quartz window 14 can be changed, and the amount of products from the quartz window 14 can be changed according to the distance between the electric field supply source 51 and the quartz window 14. become. That is, the amount by which the product from the quartz window 14 is incident on the wafer 40 and deposited can be changed. For example, to increase the amount of the product in the quartz window 14, the capacitive coupling of the RF electric field may be increased and the ion incident energy on the surface of the quartz window 14 may be increased. Therefore, the electric field source 51
What is necessary is just to shorten the distance between the quartz window 14. Quartz window 1
In order to reduce the amount of the product of No. 4, the capacitive coupling of the RF electric field may be weakened and the ion incident energy on the surface of the quartz window 14 may be reduced. Therefore, the distance between the electric field supply source 51 and the quartz window 14 may be increased.

Further, since the dry etching apparatus 5 is provided with the auxiliary electrode 15 and the film thickness measuring means 16, it is possible to grasp the deposition rate of the product from the quartz window 14 on the wafer 40, and further to provide feedback. By means 20, the distance between the electric field supply source 51 and the quartz window 14 can be feedback-controlled based on the measurement value from the film thickness measuring means 16. As a result, the thickness of the deposit when the product from the quartz window 14 enters and deposits on the wafer 40 can be adjusted, so that the reaction product generated from the wafer 40 re-enters the wafer 40. The amount of the deposit and the deposit of the product from the quartz window 14 on the wafer 40 can be adjusted to the optimal amount. This adjustment can be made automatically. Therefore, even with the dry etching apparatus 5, the dimensional conversion difference can be accurately controlled, and a stable etching process with a small dimensional conversion difference can be realized.

In this dry etching apparatus 5,
Although the case where the distance changing unit of the present invention changes the relative distance between the electric field supply source and the quartz window by moving the electric field supply source has been described, the present invention is not limited to this. For example, the relative distance between the electric field supply source and the quartz window may be changed by moving the quartz window together with the chamber, and by moving both the electric field supply source and the quartz window, the electric field supply source and the quartz window may be changed. The relative distance to the window may be changed.

Next, a second embodiment of the dry etching method according to the present invention will be described. In this dry etching method, similar to the dry etching method of the first embodiment,
In the etching process, the thickness of the deposit obtained by depositing the product generated from the window provided in the chamber by the plasma on the wafer during the etching process is determined in-situ.
u is measured (first step). Then, the thickness of the deposit subsequently deposited on the wafer is adjusted based on the measured thickness of the deposit (second step).

However, unlike the method of the first embodiment, the thickness of the deposit in the second step is adjusted here by changing the relative distance between the electric field supply source and the window. As described above, when the distance between the electric field source and the window is changed, the energy of ions incident on the window changes, so that the amount of the product from the window corresponding to the distance between the electric field source and the window is changed. Can be changed. That is, it is possible to change the amount by which the product from the window enters the wafer and deposits.

In the above method, the product generated from the window is:
The thickness of the deposit when deposited on the wafer is measured, and the relative distance between the electric field supply source and the window is feedback-controlled based on the thickness of the deposit obtained. It is possible to adjust the thickness of the deposit that is incident on the wafer and deposited. Therefore, it is possible to adjust the amount of the deposit, which includes the reaction product generated from the wafer to re-enter the wafer and the product from the quartz window to be deposited on the wafer, to the optimal amount. Therefore, even with the above dry etching method, it is possible to perform an etching process with a small dimensional conversion difference and an over-etching resistance, so that a pattern with high dimensional accuracy can be formed.

Next, a fourth embodiment of the dry etching apparatus according to the present invention will be described with reference to FIG. Here, a case where the apparatus of the present invention is applied to an IPC type etching apparatus will be described. The same components as those in the first embodiment described with reference to FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. As shown in FIG.
1 is different from the dry etching apparatus 1 shown in FIG.
The difference is that the zero gas controller 63 is controlled.

That is, the dry etching apparatus 6 has gas supply means 60 for supplying an etching gas for generating plasma into the chamber, similarly to the dry etching apparatuses 1, 3, and 5 described above. Gas supply means 6
Numeral 0 denotes a supply source 61 of the etching gas and a supply pipe 62 formed from the supply source 61 to the side wall of the chamber 10.
And a gas controller 63 for adjusting the supply amount of the etching gas. In addition, in the dry etching apparatus 6, similarly to the above-described dry etching apparatus 1, the auxiliary electrode 15 is provided in the vicinity of the wafer 40 mounted on the stage 11. Chamber 10
Above the auxiliary electrode 15 and above the auxiliary electrode 15,
5, the so-called in-sit
A film thickness measuring means 16 for measuring with u is provided. The film thickness measuring means 16 comprises, for example, an optical film thickness meter.

On the other hand, based on the thickness of the deposit measured by the film thickness measuring means 16, the feedback means 20 deposits on the wafer 40 and the auxiliary electrode 15 on the stage 11 from the quartz window 14. It adjusts the thickness of the object. As shown in FIG. 2, the feedback unit 20 includes a main body 23 including a memory 22 and a control unit 23, a display unit 24, and the like.
An input unit 25 is provided. Here, the feedback means 20 is connected to the film thickness measuring means 16, the gas controller 63, and the end point detecting means (not shown).

In this embodiment, the memory 22 stores data on the correlation between the supply amount of the etching gas and the amount of change in the thickness of the deposit deposited on the auxiliary electrode 15 (for example, the deposition rate). is there. This relationship is obtained in advance by an experiment and stored in the memory 22. Control unit 21
Is to output a signal to the gas controller 63 to change the supply amount of the etching gas based on the data of the thickness of the deposit measured by the film thickness measuring means 16. For example, when the data of the thickness of the deposit is sent from the film thickness measuring means 16, the control unit 21 determines the deposition rate based on the temporal change, and uses the determined deposition rate and the data stored in the memory 22. The supply amount of the etching gas is changed. The display unit 24 and the input unit 25 have the same functions as those of the feedback unit 20 of the dry etching apparatus 1 described above.

In the feedback means 20 having the above-described structure, conditions set in advance for performing the etching process, that is, conditions such as a set deposition rate when the product generated from the quartz window 14 is deposited on the wafer 40. Is input from the input unit 25 to the control unit 21. For example, when performing an etching process of over-etching after the main etching of the wafer 40, the set deposition rate is input at each of the main etching and the over-etching. At this time, the respective set deposition rates are input under such a condition that the deposition rate during over-etching is higher than the deposition rate during main etching.

When the etching of the wafer 40 is started and the data of the thickness of the deposit is sent from the film thickness measuring means 16 to the control unit 21, the control unit 21 obtains the deposition rate from the sent data. Then, the supply amount of the etching gas is adjusted by feedback using the data stored in the memory 22 so that the obtained deposition rate becomes the above-described set deposition rate. Further, when the end point detection signal of the main etching is sent from the end point detection means, the control unit 21 adjusts the supply amount of the etching gas by feedback so that the set deposition rate at the time of overetching is obtained.

When the supply amount of the etching gas is changed,
Since the number of ions incident on the window changes, the amount of products from the window can be changed according to the supply amount of the etching gas. That is, it is possible to change the amount by which the product from the window enters the wafer and deposits. In this dry etching apparatus 5, the auxiliary electrode 15 and the film thickness measuring means 16
And the feedback means 20, the deposition rate of the product from the quartz window 14 on the wafer 40 can be grasped, and the feed rate of the etching gas can be feedback-controlled based on the grasped thickness of the deposit. Can be.

As a result, the thickness of the deposit when the product from the quartz window 14 enters the wafer 40 and deposits can be adjusted, and the reaction product generated from the wafer 40 The amount of the deposit, which is the sum of the re-incident one and the one from which the product from the quartz window 14 deposits on the wafer 40, can be adjusted to an optimal amount. This adjustment can be made automatically. Therefore, even with the dry etching apparatus 6, the dimensional conversion difference can be accurately controlled, and a pattern having a good processed shape can be obtained.

Next, a third embodiment of the dry etching method according to the present invention will be described. In this dry etching method, similar to the dry etching method of the first embodiment,
At the time of the etching process, the thickness of the deposit, which is generated by the plasma generated from the window provided in the chamber and incident on the wafer, is measured in-situ (first step). Then, the thickness of the deposit subsequently deposited on the wafer is adjusted based on the measured thickness of the deposit (second step). However, unlike the method of the first embodiment, the thickness of the deposit in the second step is adjusted here by changing the supply amount of the etching gas.

As described above, when the supply amount of the etching gas is changed, the number of ions incident on the window changes. Therefore, it is necessary to change the amount of the product from the window in accordance with the supply amount of the etching gas. it can. That is, it is possible to change the amount by which the product from the window enters the wafer and deposits. In this method, the product generated from the window measures the thickness of the deposit obtained by depositing on the wafer, and feeds back the etching gas supply based on the measured value. In addition, the thickness of the deposits in which the products from the windows are incident on the wafer and are deposited can be adjusted. Therefore, it is possible to adjust the amount of the deposit, which includes the reaction product generated from the wafer to re-enter the wafer and the product from the quartz window to be deposited on the wafer, to the optimal amount. Therefore, even with the above-described dry etching method, it is possible to perform an etching process with a small dimensional conversion difference and an over-etching resistance, so that a pattern with high dimensional accuracy can be formed.

In this embodiment, the thickness of the deposit is adjusted by changing the amount of power supplied to the electric field supply source, the distance between the quartz window and the electric field supply source, or the supply amount of the etching gas. However, the present invention is not limited to these examples as long as the thickness of the subsequent deposit can be adjusted based on the measured thickness of the deposit. For example, it is possible to adjust the thickness of the deposit by changing the type of the etching gas. Further, the dry etching apparatus and the dry etching method according to the present invention are not limited to the present embodiment, and it is needless to say that conditions and the like can be appropriately changed without departing from the gist of the present invention.

[0071]

As described above, according to the dry etching apparatus of the present invention, the auxiliary electrode is provided near the object to be etched placed in the chamber, and the thickness of the deposit deposited on the auxiliary electrode is measured. Since the film thickness measuring means is provided, the amount of change in the thickness of the deposit obtained by depositing the product from the window on the body to be etched can be grasped. Further, in the configuration having the feedback means, the thickness of the deposit from the window to be subsequently deposited can be adjusted based on the measured value of the thickness of the deposit from the film thickness measuring means. It is possible to control the amount of the deposit, which is the sum of the reaction product that reenters the object to be etched and the product from the window that deposits on the object to be etched. This control can be performed automatically. Therefore, the dimensional conversion difference can be controlled with high accuracy, and a stable etching process with a small dimensional change difference can be realized.

In the dry etching method according to the present invention,
The product generated from the window measures the thickness of the deposit obtained by depositing on the object to be etched, and adjusts the thickness of the subsequent deposit based on the obtained measurement value. The amount of the deposit, which is the sum of the reaction product generated from the substrate and the product from the window that re-enters the object to be etched and the product deposited from the window on the object to be etched, can always be an optimal amount. . Therefore, it is possible to perform an etching process with a small dimensional conversion difference and an over-etching resistance, so that a pattern with high dimensional accuracy can be formed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of a dry etching apparatus according to the present invention.

FIG. 2 is a block diagram illustrating an example of a feedback unit.

FIG. 3 is a diagram for explaining a relationship between a measured deposit thickness and a deposition rate.

4A and 4B are diagrams illustrating a wafer processing example, in which FIG. 4A is a cross-sectional view of a wafer before processing, and FIG. 4B is a cross-sectional view of the wafer after processing.

FIG. 5 is a schematic configuration diagram of a second embodiment of the dry etching apparatus according to the present invention.

FIG. 6 is a schematic configuration diagram of a third embodiment of the dry etching apparatus according to the present invention.

FIG. 7 is a schematic configuration diagram of a dry etching apparatus according to a fourth embodiment of the present invention.

FIG. 8 is a diagram illustrating a problem.

[Explanation of symbols]

1, 3, 5, 6 Dry etching apparatus 10 Chamber 14 Quartz window 15 Auxiliary electrode 16 Film thickness measuring means 17, 3
1, 51 Electric field supply source 18 Source power supply 20 Feedback means 2
DESCRIPTION OF SYMBOLS 1 Control part 40 Wafer 60 Gas supply means 63 Gas controller

Claims (11)

[Claims] 1. A dry etching apparatus for generating a plasma in a chamber having a window made of a silicon oxide-based material and etching an object to be etched placed in the chamber, comprising: An auxiliary electrode provided in the vicinity, for depositing a product generated from the window by the plasma; and an auxiliary electrode provided in the chamber, the thickness of the deposit deposited on the auxiliary electrode being reduced. A dry etching apparatus comprising: a film thickness measuring means for measuring. 2. The apparatus according to claim 1, further comprising feedback means for adjusting the thickness of the deposit to be subsequently deposited based on the thickness of the deposit measured by said film thickness measuring means. Dry etching equipment. 3. An electric field supply source for supplying an electric field to the inside of the chamber outside the chamber, wherein the feedback means changes a distance between the window and the electric field supply. And a control unit that outputs a signal to the distance changing unit so as to change a relative distance between the window and the electric field supply source based on the thickness of the deposit measured by the film thickness measuring unit. 3. The dry etching apparatus according to claim 2, wherein: 4. A gas supply means for supplying an etching gas for generating the plasma into the chamber, wherein the gas supply means has a gas controller for adjusting a supply amount of the etching gas. The feedback unit includes a control unit that outputs a signal to the gas controller to change a supply amount of the etching gas based on the thickness of the deposit measured by the film thickness measurement unit. The dry etching apparatus according to claim 2. 5. An electric field supply source provided outside the chamber and supplying an electric field into the chamber, and a power supply supplying electric power to the electric field supply source, wherein the feedback means comprises: 3. A control unit that outputs a signal to the power supply so as to change the amount of power supplied from the power supply based on the thickness of the deposit measured by the film thickness measurement unit. Dry etching equipment. 6. A dry etching method for generating a plasma in a chamber having a window made of a silicon oxide-based material and etching an object to be etched placed in the chamber, wherein the plasma is generated from the window by the plasma. A first step of measuring a thickness of a deposit on which a product is deposited on the object to be etched; and a thickness of a deposit to be subsequently deposited based on the thickness of the deposit measured in the first step. And a second step of adjusting the dry etching method. 7. In the second step, a distance between an electric field supply source provided outside the chamber and the window is changed based on the thickness of the deposit measured in the first step. 7. The dry etching method according to claim 6, wherein the thickness of the deposit deposited thereafter is adjusted. 8. In the second step, the supply amount of the etching gas supplied into the chamber is changed based on the thickness of the deposit measured in the first step,
7. The dry etching method according to claim 6, wherein the thickness of the deposit deposited thereafter is adjusted. 9. The method according to claim 9, wherein the step of changing the amount of electric power supplied to the electric field supply source is performed based on the thickness of the deposit measured in the first step. 7. The dry etching method according to claim 6, wherein the thickness of the deposit is adjusted. 10. The method according to claim 1, further comprising: depositing the deposit on the basis of the thickness of the deposit measured in the first step so that a change amount of the thickness of the deposit is constant. 7. The dry etching method according to claim 6, wherein the thickness of the deposit is adjusted. 11. The object to be etched has a layer to be etched formed on a substrate. In the etching, after performing main etching for etching the layer to be etched until the surface of the substrate is exposed, overetching is performed. Etching is performed. In the second step, based on the thickness of the deposit measured in the first step, the amount of change in the thickness of the deposit during the main etching is smaller than the amount of change in the thickness of the deposit during the main etching. 7. The dry etching method according to claim 6, wherein the thickness of the deposit to be deposited thereafter is adjusted so that the amount of change in the thickness increases in the direction of increasing the thickness of the deposit.