JP2002025977A - Dry-etching method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a dry-etching method capable of obtaining wafers having stable performance even if a plurality of the wafers are subjected to processing in a case of etching a laminated gate and ensuring the same result with a case of using actual wafer samples even when dummy wafers are used in a continuous test. SOLUTION: When a plurality of wafers are successively subjected to etching for forming multilayered film gates formed of metal and poly-Si different from each other in reactivity, the amount of an Si reaction product is properly regulated in an etching condition that is just previously set, by which a dimensional shift is restrained from occurring between a first wafer and a second wafer in an etching process. When Si dummy wafers are used in a continuous test, the amount of a reaction product is regulated in a dummy wafer etching condition, by which actual samples subjected to etching just after the dummy Si wafers can be processed without incurring a dimensional shift, so that expensive actual samples to prepare can be decreased in number.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a dry etching method used for manufacturing a semiconductor device typified by a memory or a system LSI, and more particularly to a device aging method used for stabilizing etching characteristics. .

[0002]

2. Description of the Related Art A dry etching step, which is one of the manufacturing steps of a semiconductor device, includes a step of forming an element isolation silicon (Si) trench, a step of forming a gate electrode, a step of forming bit lines and word lines, and a step of forming contact holes. There is a process, a process of forming a trench for embedding a metal, and the like. Since the material to be etched and the film structure are different in each process, diversity is required in the etching process. In an etching process requiring such diversity, a dry etching method of converting an etching gas suitable for a material to be etched into plasma is mainly used.

As a means for generating plasma used in the dry etching method, a method of irradiating an etching gas introduced into a vacuum vessel with an electromagnetic wave and dissociating the gas by the energy is generally used. Further, the plasma generation mechanism for realizing the above method is classified according to the transmission mode of the energy of the electromagnetic wave, and is composed of a capacitively coupled plasma (CCP), an inductively coupled plasma (ICP), and a magnetic field. ECR (electron synchrotron reso
nance) Plasma is present.

[0004] In the plasma thus generated, ions, electrons and radical particles are present. Radical particles in the plasma adhere to the sample surface, and ions in the plasma are incident on the surface to which the chemical reaction is promoted,
The dry etching reaction proceeds while the reaction product volatilizes.

[0005] Therefore, the apparatus used in the dry etching process includes a plasma generation mechanism, a vacuum vessel and a vacuum exhaust mechanism, a mechanism for introducing an etching gas into the vacuum vessel, a mechanism for setting a sample in a vacuum, and a macro-chemical reaction. Temperature control mechanism and RF (Ra
dio frequency) bias mechanism. In order to obtain etching characteristics suitable for the above-described various processes using a dry etching apparatus equipped with such a mechanism, it is necessary to determine the plasma characteristics such as an etching gas type, a processing pressure, an electromagnetic wave power and a chemical reaction. This is achieved by adjusting etching parameters such as a sample setting temperature and RF bias power for determining characteristics.

The fact that the etching characteristics thus obtained are reproduced and maintained stably (characteristic stability) is
A dry etching process for mass-producing semiconductor devices is required. In mass-producing semiconductor devices, a method of continuously processing a plurality of semiconductor devices is generally employed to improve throughput. For example, 25 wafers are set for an 8-inch wafer and 13 wafers are set for a 12-inch wafer, and the wafers are continuously processed one by one. That is, the term "stability of etching characteristics" as used herein means that the etching rate, base selectivity, processing dimensions, and the like are the same (there is no change over time) throughout the first and last sheets of the continuous processing. .

Further, in a mass production factory, separate etching processes using different gas plasmas are often performed by the same etching apparatus in order to improve the operation rate of the apparatus. For example, an element isolation Si trench forming step and a gate electrode forming step using different etching gases may be performed by the same Poly-Si (polycrystalline silicon) etching apparatus. In this case, it is also required for the dry etching process that each etching process is not affected by another etching process.

[0008] In response to the above-mentioned requirement that the etching characteristics are stable and that there is no influence from other etching processes, a device aging process is conventionally inserted before the etching process. The apparatus aging step is a step of removing reaction products and the like attached to the apparatus by converting the cleaning gas into plasma (first apparatus aging step).
And the step of replacing the cleaning gas (the second step of the aging of the apparatus) and the same gas species as in the etching step are turned into plasma, and radicals from the plasma and reaction products generated by the etching are attached to the apparatus. Three steps of stabilizing the container wall surface (the third step of the device aging) or at least the third step of the device aging
In general, it is composed of one step.

At this time, the third device aging step may be divided or increased depending on the number of steps of the etching step (the number of different sets of etching parameters).

On the other hand, with the increase in the degree of integration of semiconductor devices, changes have been made in device structures and materials. In the gate electrode structure, in order to reduce the gate resistance, a laminated gate (polymetal gate) of a metal such as tungsten (W) and Poly-Si is studied from the conventional structure of Poly-Si / SiO _2. Began to be. In the conventional poly-Si gate etching process, an etching gas mainly containing chlorine and bromine was used.However, when tungsten is etched using these gases, the vapor pressure of the reaction product is low, so the etching is performed. The reaction does not proceed easily. That is, a substance having a low volatility of a reaction product, such as tungsten or copper, has a low etching reactivity. On the other hand, when a fluorine (F) -based gas is used, the vapor pressure of the reaction product is higher than when chlorine is used. Therefore, when etching the above-mentioned laminated gate, two kinds of gas systems are used, such as a tungsten gas in the upper layer and a poly-Si gas in the lower layer, such as chlorine and bromine.

In accordance with such a change in the structure of the semiconductor device, not only the etching process but also the device aging process,
In particular, the third step of the device aging must be newly considered. For example, in the case where the above-described laminated structure is subjected to the etching treatment, since there are two types of gas systems to be etched, the third step of the device aging is also divided into two, and the radical of each gas and the reaction product of the metal are separated. Both poly-Si reaction products need to be deposited on the wall.

Since the main purpose of the conventional apparatus aging step is to attach the radicals and reaction products of the respective gases to the wall surface, the processing time of the third step of the apparatus aging is usually sufficiently long. Specifically, FIG.
In the case of etching a laminated gate as shown in (a) using the steps shown in Table 1, the time of the third step of the aging of the device is at least 50 s (sec) or more in a tungsten (W) etching gas system, and It was common to use 55 s or more in total for the gas system for Si etching and the gas system for over-etching.

[0013]

[Table 1]

Table 2 shows an example of an aging step before improvement based on such a conventional concept.

[0015]

[Table 2]

After confirming that the aging process examined in this way does not adversely affect the etching process, a test of the stability of the etching characteristics (no change over time) is performed as a final test for mass-producing semiconductor devices. Done. In this case, a continuous test of 100 or more sheets is performed, including the device aging step and the cleaning step which are inserted every tens of sheets. From the viewpoint of cost and preparation time, the number of actual device samples should be as small as possible from the viewpoint of cost and preparation time, and Si dummy wafers (Si dummy wafers are solid wafers with no devices or patterns formed) Is often used. Therefore, it is necessary to newly examine the conditions for etching the Si dummy wafer so as to obtain the same result as when all of the continuous tests are performed on actual samples.

Also, since the sample used in the above-described device aging process is generally a Si dummy wafer, the conditions for etching the Si dummy wafer used in the device aging process and the continuous test are altered in those processes. It is desirable to be performed under such difficult conditions.

[0018]

The tungsten 203 / Poly-Si material 204 / SiO having the structure shown in FIG.
_{In the case where two} laminated gates (polymetal gates) made of 2 are processed successively using aging conditions as shown in Table 2 below, the first gate after aging,
FIG. 2 (b) shows the etching finish dimension 207 of the second sheet.
As shown in FIG. 5, there is a problem that the size becomes larger than the mask size 201.

In order to confirm the stability of the apparatus, after the aging step of the apparatus, the actual samples were placed on the first, second, fifteenth, and twenty-fifth sheets.
When the continuous etching process was performed on a plurality of sheets, there was a problem in that the shape shift of the 25th sheet became larger than that of the first and second sheets.

According to the present invention, in the case of etching the above-mentioned laminated gate, the shape aging in the etching step immediately after the aging is improved by setting the apparatus aging step to an appropriate condition, and stable performance is obtained even when a plurality of wafers are processed. It is a first object to obtain the following. It is a second object of the present invention to obtain the same result as in a case where an actual wafer sample is flown even when a Si dummy wafer is used in a continuous test.

[0021]

As a result of the cross-sectional shape evaluation, the dimensional shift during the continuous evaluation is as shown in FIG.
It turned out to be fat. Therefore, it is considered that the aging condition is likely to affect the tungsten etching, and the time of each step of the conventional aging shown in Table 2 is changed to continuously process two W wafers.
The change in the etching rate was examined. Table 3 shows the results of this experiment.

[0022]

[Table 3]

Under the conventional aging conditions, it was found that the W rate of the first sheet was 4.6 nm (nanometer) / min (min) slower than the rate of the second sheet. In addition, when the wavelength (W) of 430 nm is separated from the plasma at the time of etching and the time change of the emission intensity is examined, the emission intensity (waveform A) 301 at the time of the conventional aging as shown in FIG. 3 is obtained. Light emission intensity (waveform A) 301 during conventional aging
It can be seen that the intensity gradually decreases from the start of etching and has a minimum value, and then the intensity decreases because the W etching ends.

The emission intensity of the tungsten (W) is determined by the time Ta ₂ = 0 s and the time Ta ₂ = 50 in steps 2 and 3.
Although there is no change in s, when the time (T _a2 ) in step 4 is shortened, it is found that the emission intensity rises at the start of etching and decreases at the end of etching as shown in FIG. 3 (just after new aging). Light emission intensity at the time of etching (waveform B) 302). At this time, the rates of the first and second wafers are the same within 1.5%, and the etching rate of the first wafer is also 75.3 nm / m.
From in to 79.7 nm / min, it was newly found that a factor inhibiting the W etching rate was reduced. Then, as for the shape of the first and second sheets at that time, as shown in FIG. 2C, a vertical shape 208 having no dimensional shift could be obtained.

From these results, it was found that the phenomenon that the dimension of W in the conventional aging process was increased was caused by a large amount of the Si reaction product released in the aging step 4. That is, W etching in the etching process is sensitive to the amount of the reaction product in the aging step 4 which is the immediately preceding step. The larger the amount, the lower the W etching rate and the more the Si reaction product is deposited on the W side wall. It was found that a dimensional shift as shown in FIG.

According to the same consideration, the condition for etching the Si dummy wafer during the continuous test can also be reduced by suppressing the reaction products of Si, thereby eliminating the increase in dimension during the shape etching immediately after the Si dummy wafer.

Therefore, the first object can be achieved by appropriately adjusting the reaction product released in the final step of the aging process. Similarly, it has been found that the above-mentioned second object can be achieved by appropriately adjusting the amount of the reaction product even under the conditions for etching the Si dummy wafer in the etching step.

As described above, the present invention provides a multi-layer structure film composed of a material having low etching reactivity and a material having high etching reactivity including Si (silicon) and SiO ₂ (silicon dioxide). A step of continuously etching with a dry etching apparatus, and before, after, during, or one of the timings of performing the etching step,
A step of performing aging on a dry etching apparatus to stabilize continuous processing, and in a dry etching method using gas plasma with the same molecules and atoms as in the etching step during the aging step, immediately before the etching step SiO ₂ in the aging step performed in
Etching rate greater than 2 nm / min and Si
Under the condition that the etching rate is 100 nm / min or more, or the condition that the Si etching rate / SiO ₂ etching rate ratio is less than 50, the processing time of the aging step performed immediately before the etching step is as follows:
A dry etching method characterized in that the processing time is equal to or less than the processing time of an etching step using gas plasma using the same molecules and atoms.

Further, the present invention provides a method of forming a plurality of laminated films composed of a material having a low etching reactivity and a material having a high etching reactivity including Si (silicon) and SiO ₂ (silicon dioxide). In the step of etching with a dry etching apparatus, before and after performing the etching step,
Aging the dry etching apparatus to stabilize the continuous processing in the middle or at one of the timings, and in the aging step, the gas plasma using the same molecules and atoms as in the dry etching step. In the dry etching method using, the aging step performed immediately before the etching step
₍₂₎ A dry etching method characterized in that the etching rate is 2 nm / min or less, or the Si etching rate / SiO ₂ etching rate ratio is 50 or more.

Further, the present invention provides a step of continuously etching a plurality of laminated films composed of a material having a low etching reactivity and a material having a high etching reactivity including Si (silicon) by a dry etching apparatus. And before, during, or during the etching step, or one of them.
Aging the dry etching apparatus to stabilize the continuous processing at the timing, and
In a dry etching method using gas plasma of the same molecules and atoms as in the etching step during the aging step, it is configured that the Si etching rate in the aging step performed immediately before the etching step is less than 100 nm / min. A dry etching method is provided.

Further, the present invention provides a step of continuously etching a plurality of laminated structure films composed of a material having a low etching reactivity and a material having a high etching reactivity including Si (silicon) by a dry etching apparatus. And before, during, or during the etching step, or one of them.
Aging the dry etching apparatus to stabilize the continuous processing at the timing, and
In a dry etching method using gas plasma with the same molecules and atoms as in the etching step during the aging step, the product of the Si etching rate, the aperture ratio, and the processing time in the aging step performed immediately before the etching step is the same. Provided is a dry etching method characterized by being configured to be equal to or less than a product of an Si etching rate, an aperture ratio, and a processing time in an etching step using gas plasma of molecules and atoms.

Further, according to the present invention, in the above-mentioned structure, when the above-mentioned continuous processing is performed, an Si dummy wafer is mixed in an actual sample wafer of a laminated structure film, and the Si dummy wafer to be processed is formed. Under the condition that the etching conditions are higher than the SiO ₂ etching rate of 2 nm / min and the Si rate is 100 nm / min or more, or the condition that the Si rate / SiO ₂ etching rate ratio is less than 50, A dry etching method characterized in that the processing time is less than or equal to the processing time in the etching step of an actual sample wafer using gas plasma of the same molecules and atoms.

Further, according to the present invention, in the above-described structure, when performing the continuous processing, the Si dummy wafer is mixed with an actual sample wafer of the laminated structure film, and the Si dummy wafer to be processed is provided. The dry etching method is characterized in that the etching conditions are such that the SiO ₂ etching rate is 2 nm / min or less, or the Si etching rate / SiO ₂ etching rate ratio is 50 or more.

Further, according to the present invention, in the above structure, when performing the continuous processing, the Si dummy wafer is mixed with the actual sample wafer of the laminated structure film, and the Si dummy wafer to be processed is provided. A dry etching method characterized in that the etching condition of (1) is configured to be less than 100 nm / min.

Still further, according to the present invention, in the above structure, when the continuous processing is performed, a Si dummy wafer is mixed in an actual sample wafer of a laminated structure film, and the Si dummy wafer to be processed is provided. The dry etching method, wherein the product of the Si etching rate, the aperture ratio, and the processing time is equal to or less than the product of the Si etching rate, the aperture ratio, and the processing time for the actual sample wafer. provide.

[0036]

Embodiments of the present invention will be described below in detail with reference to the drawings.

Embodiment 1 An embodiment of the present invention in the case of continuously etching a polymetal gate sample having a laminated structure shown in FIG. 2 will be described below. The laminated structure in FIG. 2A is a structure before performing a step of forming a gate electrode of a memory or a system LSI. As a typical structure, a Si substrate 2
After forming a gate insulating film (film thickness 1 nm to 7 nm) on the substrate 06, a Poly-Si material (film thickness 50 nm to 100 nm) 2
04, tungsten (film thickness 50 nm to 150 nm) 20
3 and a memory section of an exposure apparatus or the like is used in a range of 0.1 μm to 0.2 μm.
SiN patterned with m-width lines and spaces,
In this embodiment, a sample composed of a mask material 202 made of Si ₃ N ₄ or the like (having a thickness of 150 nm to 300 nm) was used.

The size shift amount indicates a difference between the finished etching size 207 and the mask size 201 before etching. The etching apparatus used was a UHF wave ECR etching apparatus. This apparatus uses a 450 MHz UHF wave as an electromagnetic wave for generating plasma.
This is a CR plasma etching apparatus.

Next, Table 1 shows the etching conditions for etching 25 samples of FIG. 2A. Step 1 is a condition in which tungsten 203 is etched at a tungsten etching rate of 80 nm /
min. Step 2 is a condition where the Poly-Si material 203 is etched and the Poly-Si etching rate is 25.
0 nm / min, SiO ₂ etching rate is 10 nm
/ Min. Step 3 is a so-called over-etching step for removing Poly-Si 203 completely, in which the Si etching rate is 200 nm / m2.
This is a high selectivity condition in which the in, SiO ₂ rate is 0.8 nm / min and the oxide film selectivity is 250.

In each step, an etching gas as shown in Table 1 was used. Gas A is a gas serving as an etchant of Poly-Si containing chlorine or bromine, gas B is a gas used for obtaining selectivity with a gate oxide film or a mask material 201, and gas C is a tungsten etchant containing fluorine. Gas. Step 2, Step 3
The same gas species has been used to, at the time of over-etching, and the SiO ₂ rate below 2 nm / min to increase the proportion of gas B for do not penetrate through the gate insulating film. In this embodiment, Step 2 and Step 3 have the same gas system and a vertical shape is obtained. However, in some cases, different gas systems may be used.

The etching time depends on the thickness of each of the tungsten 203 and the poly-Si material 204 and the etching rate in each step. Table 1 shows the etching time of the sample used this time. is there.

Table 4 shows the conditions of the device aging process to which the present invention is applied.

[0043]

[Table 4]

This aging step uses a Si dummy wafer and was performed before the etching step. Step 1 is an apparatus aging first step for removing a reaction product of another etching step executed previously and cleaning the apparatus.
Step 2, Step 2 is an aging second step of replacing the gas used in Step 1 for the etching step, Step 3 is Step 3 of the apparatus aging for adapting the gas used for tungsten etching to the apparatus, Step 4
Is a device aging fourth step of adapting the gas used for Poly-Si etching and over-etching to the device.

The gas used in the aging step of the apparatus is a fluorine-based cleaning gas D which reacts with the gases A, B, and C used in the etching step and the reaction products and the like attached to the apparatus to remove them. In the gate electrode forming step, gas A is Cl ₂ or HBr, gas B is O ₂ or N ₂ , gas C
Represents CF ₄ , C ₄ F ₈ , C ₂ F ₆ , CHF ₃ , C ₅ F ₈ , SF ₆ ,
As the gas D, SF ₆ is mainly used.

In this embodiment, the number of steps for cleaning the apparatus is one. However, the processing time may be increased or the same gas may be used under different plasma conditions, depending on the location of the deposit peculiar to the structure of the etching apparatus. Or to add.
Aging step 2 is for gate etching:
It may be performed only with gas A.

In the aging step 3 and the aging step 4, if the type of gas used for the poly-Si etching and the gas used for the over-etching are the same as in this case, it is not necessary to divide the aging step. 2 and step 3 are different gas systems,
Alternatively, when a step with a different additive gas is inserted during the tungsten etching, it is preferable to change the step of the aging step according to the type of gas used.

In the aging step 3 and the aging step 4, the composition ratio of the gas B was made lower than that in the etching step to lower the oxide film selectivity. This is to prevent the surface of the Si dummy wafer from being deteriorated. It is known that if the Si dummy wafer is etched under the conditions of Steps 1 and 3 of the etching process, the surface of the Si dummy wafer becomes black or the surface is deteriorated.

Therefore, in order to be able to use the same Si wafer many times in the device aging process,
Conditions that do not alter the surface of the dummy wafer, that is, the SiO ₂ etching rate is 2 nm / min or more, or the selectivity to oxide film (Si etching rate / SiO
₍₂ etching rate ratio) low selectivity condition of less than 50 may be used. However, usually, under such conditions, the Si etching rate is 100 nm / min or more, and the SiCl
_Since many reaction products such as _x , SiCl _x O _y , or SiBr _x , SiBr _x O _y are generated, when Step 4 is performed for 60 s or more as shown in Table 2, etching is performed as shown in FIG. This resulted in a bad influence on the tungsten etching in the process.

On the other hand, the conditions in Table 4 used in this example are as follows:
The time of step 4 is set to 20 for the etching step 2.
s or less, which is the same time as the etching process step 2, so that the release amount of the reaction product is smaller than the condition in Table 2. When the first and second sheets were etched after the device aging process, the change in the light emission intensity during W etching was normal as shown by a waveform B302 in FIG.
The etching shape at this time can obtain a vertical result without a dimensional shift as shown in FIG.

In order to make it difficult for the reaction product of Poly-Si to be released, the selectivity is improved by lowering the gas A / B ratio within a range where the surface of the Si dummy wafer is not visually deteriorated. Also obtained the same effect. This is clear from the results in Table 3. When the rate was measured under the aging condition at this time, the selectivity to the oxide film was 50,
_{The two} rates were 2 nm / min.

In order to make it difficult to release the reaction product of Poly-Si, the processing pressure is 0.4 Pa or less, the UHF power is 400 W {watt}, and the RF bias power is 15 W.
W or less, the Si etching rate is 100 nm /
min. When these conditions were used in the device aging step 4 and continuous processing was performed, as shown in FIG.
A shape without dimensional shift was achieved within 2.5% of the first and second samples of the actual sample.

The conditions (Si etching rate and processing time) of the device aging step 4 in the present embodiment use the same gas system as in the etching step 2, so that the reaction product of Poly-Si is actually released. The etching time was set to 20 s or less in the etching step 2. It is more effective to set this to be equal to or less than the product of the Si etching rate in the etching step, the aperture ratio of the actual sample, and the processing time. By setting the Si rate and the time in the aging step in this way, an amount equivalent to the amount of the reaction product actually released in the actual sample can be released at the time of aging.

Here, the aperture ratio is the ratio of the area to be etched to the entire area of the wafer. For example, the Si etching rate in the etching step 2 is 250 nm /
min, the aperture ratio of the actual sample is 80%, and the processing time is 2
0 s, and when the Si etching rate in the device aging step 4 is 100 nm / min, the time of the device aging step 4 may be set to 40 s or less.

In the UHF-ECR etching apparatus, in order to set the Si etching rate to 100 nm / min or less with the same gas species, the processing pressure is adjusted to 0.4 Pa or less, the UHF power is adjusted to 400 W, and the RF bias power is adjusted to 15 W or less. Obtained. When this condition was used in the apparatus aging step 4, the dimensional shift immediately after aging was within 1%, as shown by the point 503 in FIG. 5, and could be further improved.

If the throughput is not considered, a method in which the time between the aging step and the etching step is 10 minutes or more and the reaction products are appropriately exhausted and then etched is also effective. Further, it goes without saying that the rate of Si and SiO ₂ can be adjusted to the conditions of the present invention not only in the etching apparatus used this time but also in other etching apparatuses using CCP plasma or ICP plasma.

Further, as shown in FIG.
1. Even in a metal gate made of a gate insulating film (TaO ₂ or the like) 205, dimensional anomalies can be reduced by using the device aging process to which the present invention is applied.

(Embodiment 2) An embodiment in the case of performing a continuous test of the apparatus will be described below. The etching apparatus used, the structure of the actual sample, and the conditions of the aging step are the same as those described above. First etching,
Actual samples were used for the second, fifteenth, and twenty-fifth sheets, and the rest were Si dummy wafers. By using the Si dummy wafer in this way, cost and preparation period can be reduced. Table 1 shows conditions for etching the actual sample, Table 4 shows aging conditions, and Table 5 shows Si dummy etching conditions to which the present invention is applied.

[0059]

[Table 5]

When a 25-sheet continuous test was performed under the above conditions, as shown in FIG. 2C, the 25th actual sample could be etched vertically without any dimensional shift. FIG. 5 shows a comparison with the case where 25 actual samples were continuously etched, and it was confirmed that the same result as that obtained when all of the actual samples were continuously etched was obtained.

Also, when etching the Si dummy wafer,
In order to make it difficult to release the reaction product of Poly-Si,
The same effect was obtained even if the selectivity was improved by lowering the gas A / B ratio within a range where the surface of the Si dummy wafer was not visually altered. This is apparent from the results of Table 3 and the examination of the aging described above. When the rate was measured by etching at this time, the selectivity to oxide film was 50,
_{The two} rates were 2 nm / min.

The same effect is obtained as in the case of device aging.
Obtained by setting the Si etching rate to 100 nm / min or less, or setting the Si rate and time of the final step of the Si dummy wafer to the product of the Si etching rate in the etching process, the aperture ratio of the actual sample, and the processing time. Was completed.

As described above, in the actual sample etching process or the continuous test process, the flow of the process to which the present invention is applied as shown in the above embodiment and the outline of the result are summarized in FIG. When the actual sample etching was performed after the apparatus aging step of the present invention, there was no dimensional shift abnormality from the first sheet to the 25th sheet, and the result shown in FIG. 2C was obtained. On the other hand, in the continuous test process, after the aging process of the present invention, 1,
Actual sample wafers on 2, 15, 25, and 2000 sheets
In addition, a Si dummy wafer was inserted, and the etching conditions of the present invention were applied during the etching of the Si dummy wafer. It could be etched.

[0064]

As described above, according to the present invention, metal and
In the case where a plurality of multi-layer gates having different reactivities such as Poly-Si are continuously etched, by adjusting the amount of a reaction product of Si to an appropriate amount under the immediately preceding aging condition, the first one of the etching steps can be performed. The size shift abnormality of the second sheet can be eliminated.

In the case where the continuous test is performed on a Si dummy wafer, the shape of the actual sample immediately after the Si dummy wafer can be processed without dimensional shift abnormality by adjusting the amount of the reaction product in the Si dummy wafer etching condition.
The need to prepare costly real samples is reduced.

[Brief description of the drawings]

FIG. 1 is a flowchart of a dry etching method to which the present invention is applied.

FIG. 2 is a view showing a processing example of a laminated polymetal gate structure.

FIG. 3 is a diagram showing a time change of each light emission intensity during tungsten etching depending on whether or not the present invention is applied.

FIG. 4 is a diagram showing a processing example of a metal gate structure.

FIG. 5 is a diagram showing a result of measuring a dimensional shift amount in a continuous test of 25 wafers when only real samples and Si dummy wafers are mixed.

[Explanation of symbols]

201: mask dimensions before etching, 202: mask material, 203: tungsten, 204: Poly-Si material,
205: Gate insulating film, 206: Si substrate, 207: Finished etching size, 301: Emission intensity at the time of conventional aging (waveform A), 302: Emission intensity at the time of etching immediately after application of the present invention (waveform B), 401 ... Tungsten, 501: Point indicating the dimensional shift amount of the first sheet when Si dummy wafers are mixed, 502 ... Point indicating the dimensional shift amount of the second sheet when Si dummy wafers are mixed, 503: Point indicating the dimensional shift immediately after aging ., 504... A line indicating a change in the dimensional shift amount when all 25 wafers are actually sampled; 505... A point indicating the fifteenth dimensional shift amount when a Si dummy wafer is mixed; A point indicating the amount of dimensional shift of the sheet.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazunori Tsujimoto 1-280 Higashi Koigakubo, Kokubunji-shi, Tokyo F-term in Central Research Laboratory, Hitachi, Ltd. 5F004 AA15 AA16 BA14 BB11 BB18 CA08 CB02 DA00 DA01 DA02 DA04 DA16 DA18 DA25 DA26 DA30 DB02 DB03 DB10 EA07 EB02

Claims (5)

[Claims] 1. A dry etching apparatus for continuously forming a plurality of laminated films composed of a material having low etching reactivity and a material having high etching reactivity including Si (silicon) or SiO ₂ (silicon dioxide). And aging the dry etching apparatus in order to stabilize continuous processing before, after, during or at one timing of performing the etching step. In a dry etching method using gas plasma of the same molecules and atoms as in the etching step, the aging step performed immediately before the etching step has an SiO ₂ etching rate of more than 2 nm / min, and Conditions that the etching rate is 100 nm / min or more, or Si etching rate Under the condition that DOO / SiO ₂ etching rate ratio is less than 50, the processing time of the aging step performed immediately before the etching step, the same molecule, the following processing time of the etching process using a gas plasma by atomic A dry etching method, characterized in that: 2. A dry etching apparatus for continuously forming a plurality of laminated structure films comprising a material having low etching reactivity and a material having high etching reactivity including Si (silicon) or SiO ₂ (silicon dioxide). And aging the dry etching apparatus in order to stabilize continuous processing before, after, during or at one timing of performing the etching step. In a dry etching method using gas plasma of the same molecules and atoms as in the dry etching step, the aging step performed immediately before the etching step has an SiO ₂ etching rate of 2 nm / min or less, or a Si etching. that rate / SiO ₂ etching rate ratio is configured to be a more than 50 A characteristic dry etching method. 3. A step of continuously etching a plurality of laminated films composed of a material having low etching reactivity and a material having high etching reactivity including Si (silicon) by a dry etching apparatus; Aging the dry etching apparatus in order to stabilize continuous processing before, after, during, or at one of the steps of performing the step, and the etching step includes A dry etching method using a gas plasma of the same molecules and atoms, wherein the Si etching rate in an aging step performed immediately before the etching step is less than 100 nm / min. 4. A step of continuously etching a plurality of laminated films composed of a material having a low etching reactivity and a material having a high etching reactivity including Si (silicon) by a dry etching apparatus; Aging the dry etching apparatus in order to stabilize continuous processing before, after, during, or at one of the steps of performing the step, and the etching step includes In a dry etching method using gas plasma of the same molecules and atoms, the product of the Si etching rate, the aperture ratio and the processing time in the aging step performed immediately before the etching step is the same as that of the gas plasma of the same molecules and atoms. Is less than or equal to the product of the Si etching rate, the aperture ratio, and the processing time in the etching process using The dry etching method which is characterized in that the cormorants configuration. 5. When performing the continuous processing, an Si dummy wafer is mixed in an actual sample wafer of the laminated structure film, and an etching condition of the Si dummy wafer to be processed is SiO ₂ etching. Rate 2nm
/ Min and a Si rate of 100 nm / min or more, or a condition that the Si rate / SiO ₂ etching rate ratio is less than 50.
2. The dry etching method according to claim 1, wherein the processing time of the dummy wafer is equal to or less than the processing time in the etching step of the actual sample wafer using gas plasma of the same molecules and atoms.