JP3339136B2 - Dry etching method and dry etching apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dry etching method and a dry etching apparatus. INDUSTRIAL APPLICABILITY The present invention can be used, for example, as a dry etching method and a dry etching apparatus used in manufacturing electronic materials (semiconductor devices and the like).

In the field of semiconductor devices, as miniaturization and integration are further advanced, and particularly, for example, as the integration density of VLSIs is advanced, the demand for fine processing technology is becoming more and more severe. This is not an exception in the dry etching process, and various studies are being conducted with the aim of high precision processing.

In the field of dry etching technology,
It is basically required to properly control the etching conditions. If the etching conditions are not appropriate, the resulting etched shape will not be the desired one. For example, a rectangular pattern may be desired, but a tapered shape or side etching may occur, resulting in an undercut pattern. Because it happens. However, it is not always easy to always maintain proper etching conditions and to perform good etching.

For example, taking the field of semiconductor devices as an example, in the processing of Si materials such as gate materials made of poly-Si or so-called polycide, gas systems such as HBr and Cl _{2 have} recently been used. It is desirable to remove CFCs and achieve a high selectivity. The same applies to so-called trench etching for forming an opening in a Si-based material. The process with these etching gases involves reactants generated during etching,
In particular, the structure is controlled by utilizing the reaction products generated by the reaction between the material to be etched and the etching gas, such as SiBr _x and SiCl _x, while protecting the side walls.

[0005] However, the amount of these reaction products is
Since the area to be etched is largely determined by the area to be etched (determined by the aperture ratio defined by the wafer size or the like, which is the total area of the material to be etched, or by the aperture ratio to be etched defined by the opening area of a mask such as a resist), Even when the etching conditions are used, a difference occurs in the dimension conversion difference and the cross-sectional shape of the etching. Therefore, after all, in order to determine appropriate conditions, it was necessary to review the conditions for each sample.

[0006] Therefore, it is difficult to develop a versatile process using the prior art, and there is a need for an improved method for this.

[Object of the invention]

The present invention has been made in view of the above circumstances, and can always perform etching under appropriate conditions irrespective of the type of a material to be etched, thereby achieving appropriate etching. An object of the present invention is to provide a dry etching method and a dry etching apparatus which can easily obtain an etching shape and are versatile.

[Means for solving the problems]

According to a first aspect of the present invention, there is provided a dry etching method for etching a material to be etched using an etching apparatus capable of controlling the temperature of the material to be etched by controlling the temperature of a stage on which the material to be etched is mounted. the d with a, the changes with area to be etched
Corresponds to the amount of substance adhering as a deposit to the etching material
The controller detects a monitoring amount, and sends a signal obtained by the detection to the controller, and the controller supplies a coolant supply unit based on the obtained signal according to a relationship between the monitoring amount and an appropriate etching temperature determined in advance. By controlling the temperature of the stage on which the material to be etched is mounted by using the coolant as a temperature at which an appropriate etching temperature is obtained, the etching is performed by changing the etching temperature of the material to be etched. The dry etching method described above achieves the above object.

Here, the area to be etched refers to an area of a portion to be actually etched at the time when the etching is in progress. It is determined by the aperture ratio of the remaining etched area defined by the wafer size or the like, which is the total area of the material to be etched, or the etching aperture ratio defined by the mask opening area of a resist or the like.

The etching temperature is a temperature at which etching is performed, and is generally defined by the temperature of the material to be etched (for example, if the material to be etched is a substrate, it can be determined by controlling the temperature of a stage that supports the substrate). Can be achieved.

[0011]

Here, the monitored amount of the etching product refers to the emission intensity of the reaction product, which varies depending on the area to be etched, the mask spectrum amount, and the like. That is,
It is an amount that changes according to an amount serving as a parameter for changing a condition such as an area to be etched, and is an amount that can be monitored.

According to a second aspect of the present invention, the material to be etched is etched by using an etching apparatus capable of controlling the temperature of the material to be etched, and the etching product is stochastically attached to the material to be etched. A dry etching method that results in deposits ,
The intensity of the emission spectrum of any of the etching products is detected in an amount corresponding to the amount of the substance attached as a deposit , and a signal obtained thereby is sent to a controller, and the controller performs the above processing in advance. A dry etching method characterized in that etching is performed by changing the etching temperature of the material to be etched according to the relationship between the intensity of the emission spectrum obtained and the appropriate etching temperature that makes the adhesion probability of the deposit appropriate. This achieves the above object.

According to a third aspect of the present invention, the etching is chlorine-based.
Or dry etching using a bromine-based gas,
Reaction between the chlorine-based or bromine-based gas and the material to be etched
It is characterized by detecting the intensity of the emission spectrum of the product
The dry etching method according to claim 2, wherein
This achieves the above object . CFC-free
For example, chlorine-based and bromine-based gases (Cl ₂ , HCl, Br ₂ ,
HBr) is advantageously used. If necessary,
In some cases, it may be better to add a gas.

According to a fourth aspect of the present invention, there is provided an etching apparatus used for etching in which an etching product stably adheres to a material to be etched to form a deposit, and further comprises a stage on which the material to be etched is mounted. the temperature of the stage a etching device capable of temperature control of the object to be etched by controlling the refrigerant, and deposit the object to be etched with changes with area to be etched
Monitoring means for detecting a monitoring amount corresponding to the amount of the substance to be adhered, and, based on a signal obtained thereby, the refrigerant according to a relationship between the monitoring amount and an appropriate etching temperature determined in advance. A controller that controls a refrigerant supply unit to supply the refrigerant to a temperature at which an appropriate etching temperature is obtained, and a control mechanism that controls the temperature of a stage on which the material to be etched is mounted by the temperature-controlled refrigerant. Thus, a dry etching apparatus characterized in that etching is performed while changing the etching temperature of a material to be etched, thereby achieving the above object.

Here, the monitored amount is the same as that described above.

[0017]

According to the etching method of the present invention, the etching temperature is determined in accordance with the area to be etched which greatly affects the amount of the reaction product functioning as a sidewall protective film or the like. Etching can be realized.

Further, according to the etching method of the present invention, the etching temperature is determined according to the monitored amount of the reaction product functioning as a side wall protective film or the like, so that appropriate etching can be realized.

According to the etching apparatus of the present invention, a mechanism is provided for feeding back the etching product to the etching temperature based on the monitored amount of the etching product, so that appropriate etching can always be automatically and easily realized. Can be.

【Example】

Hereinafter, embodiments of the present invention will be described.
The present invention is, of course, not limited to the following examples, and it is needless to say that various aspects can be taken within the scope of the present invention.

Embodiment 1 In this embodiment, the present invention is applied to processing of a poly-Si gate electrode by plasma etching.
In this embodiment, a dry etching apparatus and a dry etching method for monitoring an amount of a reaction product that varies depending on an area to be etched during etching (before and after etching as necessary) and setting an optimum etching temperature based on the monitored amount. It was done.

By using this embodiment, it becomes possible to perform etching of Si-based materials having different wafer diameters and opening areas without causing a shape difference under the same etching (plasma) conditions. .

In this embodiment, as shown in FIG. 1, in the dry etching step, a step I of detecting the amount of the reaction product by the emission intensity (determining the area to be etched by the amount of the reaction product) is performed. Based on this, the setting II of the etching temperature according to the area to be etched is performed.

This embodiment will be described in further detail with reference to FIGS.

In this embodiment, the substrate to be etched is treated by using an ECR type etching apparatus capable of controlling the temperature of the substrate as the material to be etched.
-This is an example in which the Si gate electrode is etched.
As a material to be etched, as shown in FIG. 2, Poly-Si2 is deposited on the gate oxide film 3 (SiO ₂ ) on the Si substrate 4.
After the formation of a thickness of 00 nm, a resist is applied and patterned to form a resist mask 1 and an unmasked opening.

In this embodiment, a substrate wafer having a diameter of 125 mm is used. This wafer has a mask opening area of 60%
In the case of (the portion to be etched not covered with the resist mask is 60% of the whole), when the etching is performed under the following conditions, a good vertical shape is obtained as shown in FIG. It is. Working gas: Cl ₂ / O ₂ = 72/8 SCCM Pressure: 400 mPa Microwave: 850 W RF (2 MHz): 30 W Etching temperature: -10 ° C.

However, when the same conditions are applied to a sample having a diameter of 125 mm and a mask opening area of 80%,
The amount of the reaction product increases. On the other hand, since the plasma generation conditions and the gas exhaust speed are the same, the amount of SiCl _x adhering to the side walls as deposits through re-dissociation relatively increases. Therefore, this results in the occurrence of a tapered shape due to excessive deposits, and the etched shape of the portion to be etched, Poly-Si2, has a tapered shape shown in FIG.

Therefore, in the present embodiment, the amount of this reaction product is determined by the emission spectrum of SiCl (wavelength 391n).
m) A mechanism was added to the apparatus to monitor the intensity and to change the temperature in order to change the probability of SiCl _x deposition on the sample surface accordingly.

Now, when comparing the luminescence intensity of SiCl at the time of etching each sample of FIGS. 3A and 3B, as shown in FIG. 4, the intensity of SiCl is higher as shown in FIG. The luminescence intensity is proportional to the amount of luminescent species). On the other hand, as shown in FIG. 5 showing the relationship between the amount of the reaction product and the appropriate dry etching amount, the etching temperature at which the vertical shape is obtained is lower when the reaction product is smaller (A). Become.

From the above study, in this embodiment, the SiC
The relationship between the emission intensity of 1 and the optimum etching temperature is determined as shown in FIG. 6, and a feedback system for controlling the temperature based on the relationship is provided. The relationship in FIG.
For example, it can be obtained for the first wafer for each lot. Further, the same material to be etched can be obtained by measuring in advance.

That is, the etching apparatus of this embodiment is the same as that of FIG.
As shown in (1), light emission from the material to be etched 7 (substrate wafer) is detected by a light emission monitor 9 (polychromator) via a fiber 8, and a signal obtained here is detected by a controller 1.
The circulator 11 supplies a coolant to the wafer mounting electrode 71 in order to set the substrate temperature (that is, the etching temperature) according to the relationship shown in FIG.
Control the temperature of the In FIG. 7, reference numeral 5 denotes an ECR etching system part. Reference numeral 12 denotes a refrigerant supply pipe.

By using the above system, even if the Si-based materials have different opening areas as shown in FIGS. 3A and 3B, the processing can be performed under the same plasma conditions so that an anisotropic shape can be obtained. Could be done on condition.

In addition, when the wafer diameter is different (125 m
In the case where it is necessary to treat different diameters such as m diameter, 150 mm diameter, and 200 mm diameter with the same apparatus, etc.), or when the reaction products are accumulated on the inner wall of the chamber by repeating the number of steps, the excessive deposition is performed. In the case of, the same good vertical etching shape can be obtained under the same plasma condition by thinking of raising the etching temperature.

According to this embodiment, it is possible to properly process materials to be etched having different opening areas and wafer sizes under the same plasma etching conditions. In addition, even if the number of steps is increased and the reaction product accumulates in the chamber, without causing a shape difference,
Anisotropic processing can be continued. As a result, it is also possible to reduce the number of steps required for process development.

Even when it is difficult to monitor the material to be etched itself, as in the case of forming an extremely thin gate electrode, a film to be etched having a certain thickness is separately formed for monitoring. By monitoring this, the above method can be performed well.

Embodiment 2 This embodiment is the same as the above embodiment, except that bromine gas is used for etching.

The etching conditions in this case were as follows using the material to be etched in FIG. Working gas: HBr / O ₂ = 120/6 SCCM Pressure: 700 mPa Microwave: 850 W RF: 40 W Etching temperature: + 20 ° C.

A rare gas such as Ar may be added to the etching gas.

In this embodiment, light emission is detected most easily in a Br-based SiBr (426 nm).
By monitoring this using the spectrum and obtaining the same relationship as in FIG. 6, it became possible to obtain good anisotropic shapes in various samples.

Example 3 In this example, etching was performed using Al (particularly Al-1 wt% Si) as a portion to be etched, using the same Cl-based gas as in Example 1.

The apparatus used was the same as that of the first embodiment.
The emission spectrum (wavelength 406 nm) was monitored. In this embodiment, the same good etching of the Al-based material as in each of the above-described embodiments was achieved.

Embodiment 4 In this embodiment, Al (particularly Al-1 wt% Si) was etched using the same Br-based gas as in Embodiment 2 using Al as a portion to be etched.

The apparatus used was the same as that of the first embodiment.
The emission spectrum (wavelength 420 nm) was monitored. In this embodiment, the same good etching of the Al-based material as in each of the above-described embodiments was achieved.

[0045]

As described above, according to the present invention, etching can always be performed under appropriate conditions irrespective of the type of the material to be etched, so that appropriate etching can be achieved. The shape can be easily obtained, and a versatile dry etching method and dry etching apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an etching method according to a first embodiment.

FIG. 2 is a cross-sectional view of a material to be etched in Example 1.

FIG. 3 is a cross-sectional view showing an etching shape in each case according to the amount of a reaction product.

FIG. 4 is a diagram showing a relationship between a reaction product amount and luminescence intensity.

FIG. 5 is a diagram showing a relationship between an amount of a reaction product and an appropriate etching temperature.

FIG. 6 is a diagram showing a relationship between emission intensity and an appropriate etching temperature.

FIG. 7 is a diagram showing a configuration of an etching apparatus used in the example.

[Explanation of symbols]

I A step of detecting the amount of a reaction product by light emission intensity (determining an area to be etched based on an amount of a reaction product) II A step of setting an etching temperature according to an area to be etched 1 A resist mask 2 A portion to be etched (Poly-Si) Reference Signs List 3 SiO ₂ 4 Substrate (Si) 5 ECR etching system 6 Plasma 7 Material to be etched (substrate wafer) 71 Wafer stage 8 Emission monitoring fiber 9 Emission monitoring polychromator 10 Controller 11 Temperature control circulator 12 Refrigerant supply pipe

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/3065 C23F 4/00

Claims (4)

(57) [Claims] 1. A dry etching method for etching a material to be etched using an etching apparatus capable of controlling the temperature of the material to be etched by controlling the temperature of a stage on which the material to be etched is mounted, the method comprising: Echinin varies with area
It corresponds to the amount of substance that adheres as sediment to
A certain monitoring amount is detected, and a signal obtained thereby is sent to a controller, and the controller controls the refrigerant supply unit based on the obtained signal in accordance with a relationship between the monitoring amount and an appropriate etching temperature obtained in advance. do it,
A dry etching method characterized in that etching is performed by changing the etching temperature of the material to be etched by controlling the temperature of a stage on which the material to be etched is mounted with the refrigerant by setting the temperature of the coolant to a temperature at which an appropriate etching temperature is obtained. . 2. An etching apparatus for etching a material to be etched by using an etching apparatus capable of controlling the temperature of the material to be etched, wherein the etching product is deposited on the material to be etched stochastically to form a deposit. Etching method, corresponding to the amount of substances adhering as deposits to the material to be etched
The intensity of the emission spectrum of any etching product is that amount which is detected, thereby resulting signal sent to the controller, the controller may advance the intensity of the emission spectrum that has been determined to be the sticking probability of the deposit A dry etching method characterized in that etching is performed by changing an etching temperature of a material to be etched in accordance with a relationship with an appropriate etching temperature that makes the temperature appropriate. 3. The etching is dry etching using a chlorine-based or bromine-based gas, and detecting the intensity of the emission spectrum of a reaction product between the chlorine-based or bromine-based gas and a material to be etched. 3. The dry etching method according to claim 2, wherein: 4. An etching apparatus used for etching in which an etching product stochastically adheres to a material to be etched to form a deposit, and further comprises a stage on which the material to be etched is mounted, wherein the temperature of the stage is controlled by a coolant. a possible and the etching apparatus temperature control of the object to be etched by controlling the, the etching with changes with area to be etched
It corresponds to the amount of substance that adheres as sediment to
Monitoring means for detecting a certain monitoring amount, based on a signal obtained thereby, controlling a refrigerant supply unit for supplying the refrigerant in accordance with a relationship between the monitoring amount and an appropriate etching temperature determined in advance, and A controller that sets a temperature at which an appropriate etching temperature can be obtained, and a control mechanism that controls the temperature of a stage on which the material to be etched is mounted by the coolant whose temperature is controlled, thereby changing the etching temperature of the material to be etched. A dry etching apparatus characterized in that etching is performed by using a dry etching method.