JP3348768B2 - Dry etching apparatus, dry etching method, semiconductor device manufacturing apparatus, semiconductor device manufacturing method, and semiconductor device for aluminum and aluminum alloy film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for dry-etching aluminum and aluminum alloy films, a semiconductor manufacturing apparatus, a semiconductor manufacturing method and a semiconductor device mainly used for wiring of a semiconductor device.

[0002]

2. Description of the Related Art When processing aluminum and aluminum alloy films used for wiring of semiconductor devices, dry etching using plasma is currently the mainstream. In the case of dry-etching an aluminum or aluminum alloy film, aluminum and a halogen element have very high reactivity and chemically react with each other, so that etching proceeds isotropically with only an etching gas. Therefore, a method of simultaneously adding a deposition gas to protect the wiring side wall during etching is generally used.

FIG. 1 shows a typical apparatus configuration diagram. This apparatus is configured to apply a high frequency from an upper RF antenna coil and generate plasma in a vacuum chamber via a dielectric such as quartz. (A) is a structure in which gas is introduced from the center of the chamber top plate toward the wafer. In the case of this structure, the deposition gas is also supplied together with the etching gas from the center of the chamber, so that the deposition tends to be thick at the center and the wiring tends to be thin due to the shortage of the deposition gas at the periphery. Is generated. On the other hand, in (b), the “shape non-uniformity” as seen in (a) tends to be improved, but since the etching gas concentration becomes high in the peripheral portion of the wafer, the aluminum etching rate is reduced in the peripheral portion. And the uniformity of the etching rate deteriorates.

It has been considered that such non-uniformity of the shape and the etching rate in the wafer surface is caused by non-uniform distribution of the process gas. for that reason,
FIG. 2 shows a plasma processing apparatus in which gas inlets are arranged both directly above a wafer and at the periphery of a wafer.
As shown in 932, a gas inlet is provided directly above the wafer, and the gas inlet in the center is slightly directed to the outer periphery.
A parallel plate type plasma processing apparatus having an outer peripheral portion slightly inclined toward the center has been proposed. These all have the aim of making the processing uniform by making the distribution of the process gas uniform. However, when these devices are used for dry etching of an aluminum alloy film, the shape is thick at the central portion of the wafer and narrow at the peripheral portion of the wafer, and the etch rate distribution is higher and uneven at the peripheral portion of the wafer than at the central portion of the wafer. .

[0005]

In these conventional apparatuses, the reason why the "uniformity of the shape" and the "uniformity of the etch rate" are not compatible is to consider "the re-incident of the etching product". Can be easily understood.

When the gas is supplied from the center of the chamber top plate toward the wafer, the distribution of gas in the chamber and the distribution of etch rate and dimensional variation are as shown in FIG. In this figure, the horizontal axis indicates the position in the wafer radial direction. Here, “a gas contributing to etching (a gas containing Cl and Br)” and a “gas contributing to a deposit (a gas containing C and N)”
Is supplied from the gas inlet as a process gas,
The distribution is greatly affected by the position of the gas inlet. The uniformity of the etching rate depends on the distribution of “gas contributing to etching”, and the uniformity of the shape depends on the distribution of “gas contributing to deposition”. Furthermore, in the case of etching, "re-entry of the etching product" must be considered.
Since the evacuation is usually performed from the peripheral portion of the wafer, the distribution of the etching product always increases in the central portion as shown in FIG. At a position where a large amount of etching products are present, the partial pressure of the “gas contributing to etching” is reduced, and the etching rate is reduced. Further, since the same operation as the deposition is performed, the amount of dimensional variation becomes large (becomes larger than the mask size).

In the case of FIG. 3A, the distribution of the gas contributing to the etching and the distribution of the etching product have a peak at the center of the wafer and cancel each other, so that the etch rate distribution is relatively uniform. However, in the distribution of the dimensional variation, the distribution of the gas contributing to the deposit and the distribution of the etching product have a peak at the center position of the wafer, and the synergistic effect tends to make the size at the center position of the wafer larger than the mask size.

FIG. 2B shows a case where the gas is introduced from the outer periphery of the chamber toward the wafer. Since the distribution of the gas contributing to the deposition and the distribution of the etching product are opposite, the dimensional controllability is good. However, the distribution of the gas contributing to the etching is minimized at the central portion, and the distribution of the etching product is maximized at the central portion, so that the etching rate is significantly reduced at the central portion of the wafer.

Therefore, as shown in FIG. 2, an apparatus for introducing gas from directly above the wafer and from the periphery of the wafer is disclosed in Japanese Patent Application Laid-Open No. 58-13 / 1983.
FIG. 4 shows the distribution of the gas and the distribution of the etch rate and the dimensional variation when the distribution of the process gas becomes completely uniform using the apparatus proposed in No. 2932. In the case of dry etching, in most cases, air is exhausted from the peripheral portion of the wafer, so that the etching product always has a distribution that has a maximum at the central portion of the wafer. Therefore, even if the distribution of the process gas can be made completely uniform within the wafer surface, the shape becomes thicker at the center of the wafer, narrower at the periphery of the wafer, and the etch rate distribution is affected by the distribution of the etching products. The periphery of the wafer is higher and non-uniform than the center of the wafer.

[0010]

In order to solve the above-mentioned problems, in consideration of the distribution of etching products, the gas contributing to the etching has a maximum value at the center of the wafer as shown in FIG. The gas contributing to the deposit needs to be supplied so as to have a minimum value at the center of the wafer.

That is, the present invention provides a mechanism for introducing a gas contributing to etching from the center of the chamber top plate and introducing a gas contributing to deposition from the outer periphery of the chamber in a dry etching apparatus for aluminum and aluminum alloy films. It is intended to provide a dry etching apparatus characterized by having the above.

The present invention also proposes a method for dry-etching aluminum and aluminum alloy films using the above-mentioned dry-etching apparatus, and further comprises the above-mentioned dry-etching apparatus. A manufacturing method of a semiconductor device, a method of manufacturing a semiconductor device characterized by dry-etching an aluminum or aluminum alloy film using the manufacturing device of the semiconductor device, and a semiconductor device manufactured by the method are proposed. Things.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

[0014]

Next, an embodiment of the present invention will be described with reference to the drawings.

(First Embodiment) As a first embodiment, a case in which an aluminum laminated wiring is etched with C12 / BC13 / CHF3 gas will be described. FIG. 2 shows a configuration diagram of the plasma processing apparatus used in the present embodiment. This apparatus is configured to apply a high frequency from a spiral coil disposed at the top of the chamber and generate plasma in the chamber by inductive coupling. Also, a high frequency power supply is separately provided on the substrate side so that ion energy can be controlled independently. The greatest feature of this apparatus is that the gas introduction position exists not only immediately above the processing substrate but also at the outer peripheral portion of the chamber. Each gas can be introduced from either position, and each gas line is provided with a solenoid valve so that it can be easily switched.

In this embodiment, etching was performed by four different gas introduction methods, and the in-plane distribution of the Al etch rate and the in-plane distribution of the dimensional variation of the Al wiring width were compared. Table 1 below shows the four gas introduction methods.

[0017]

[Table 1]

In condition A, all gases were introduced from directly above the wafer. Under the condition B, all gases were introduced from the periphery of the wafer. Under the condition C, the gas was introduced from directly above the wafer and from the periphery of the wafer. Under condition D, the etching gas was introduced from directly above the wafer, and the deposition gas was introduced from the periphery of the wafer.
Incidentally, in the case of this embodiment, the C12 / BC13 gas plays a role of an etching gas, and the CHF3 gas plays a role of a deposition gas.

The experimental conditions in the present embodiment are as follows.

[Plasma discharge conditions] C12 / BC13 / CHF3 = 100/20/8 sc
cm, 10mTorr, Source Power: 8
00W Bias power: 120W, temp. Wall
/ Stage = 80 ° C./50° C. [Measurement method] Al etch rate measuring method: use of step gauge Aluminum wire width dimensional variation: measured from SEM photograph FIG. 6 shows the in-plane distribution of Al etch rate in the first embodiment. The results are shown. The horizontal axis indicates the Left-Right position when the orientation flat is set to Bottom, and the vertical axis indicates the aluminum etch rate. In the case of condition A, since the etching gas is introduced from the center of the wafer, the etch rate at the center of the wafer should be high,
Since a large amount of deposition gas and etching products exist in the center of the wafer, the partial pressure of the etching gas is low,
The etching rate was slightly higher at the periphery of the wafer. In the case of the condition B, the etch rate in the peripheral portion of the wafer was higher than in the condition A, and the rate in the central portion of the wafer was lower. Therefore, the rate uniformity was the worst among these four conditions. In the case of the condition C, the etch rate in the center portion of the wafer is equal to that in the condition A, but the etch rate in the peripheral portion of the wafer becomes higher, so that the uniformity is lower than in the case of the condition A. On the other hand, in the case of the condition D in which the etching gas and the deposition gas were respectively introduced from different portions, the etch rate in the peripheral portion was suppressed, and the best uniformity was obtained. This is realized by introducing an etching gas into the central portion of the wafer where the etching rate tends to decrease, and introducing a deposition gas which inhibits etching into the peripheral portion of the wafer where the etching rate tends to increase.

FIG. 7 shows the in-plane distribution of the dimensional variation of the Al wiring width in the first embodiment. The horizontal axis represents the position in the wafer as in FIG. 6, and the vertical axis represents the dimensional variation in percentage from the mask dimension before etching. In this case, if the dimensional variation is positive, it indicates that the wiring is thicker, and if it is negative, it indicates that the wiring is thinner. The evaluation was performed at a position where the wiring size was 0.4 μm and the space between the wirings was 2.0 μm.

In the case of condition A, the central portion of the wafer was made thicker because both the etching gas and the deposition gas were introduced from the central portion, and conversely, the wiring was thinner at the peripheral portion than the mask due to lack of side wall protection components. . In the case of the condition B, the gas is introduced from the peripheral portion of the wafer, so that the processing at the central portion of the wafer can be performed almost in accordance with the mask dimension. However, the peripheral portion is affected by the deposition gas, and the wiring tends to be slightly thick. Indicated. In the case of the condition C, the central portion of the wafer tended to be thicker than the mask size. This is because, as described above, not only the deposition gas but also a large amount of etching products are present in the central portion of the wafer. On the other hand, condition D
In this case, since the deposition gas is added from the peripheral portion of the wafer, there is no excessive supply of the deposition gas to the central portion of the wafer while preventing side etching at the peripheral portion of the wafer. Therefore, condition D resulted in the least dimensional change in the wafer surface among these four conditions.

From the results of FIGS. 6 and 7, it can be said that when etching the aluminum laminated wiring with C12 / BC13 / CHF3 gas, the condition D is the most excellent gas introduction method.

(Second Embodiment) As a second embodiment, a case in which an aluminum laminated wiring is etched with C12 / BC13 / N2 gas will be described. The plasma processing apparatus used in this embodiment is the same as in the first embodiment.

Also in this example, etching was performed by four different gas introduction methods, and the in-plane distribution of the Al etch rate and the in-plane distribution of the dimensional variation of the Al wiring width were compared. Table 2 below shows the four gas introduction methods.

[0026]

[Table 2]

Under the condition A, all gases were introduced from directly above the wafer. Under the condition B, all gases were introduced from the periphery of the wafer. Under the condition C, the gas was introduced from directly above the wafer and from the periphery of the wafer. Under condition D, the etching gas was introduced from directly above the wafer, and the deposition gas was introduced from the periphery of the wafer.
Incidentally, in the case of this embodiment, the C12 / BC13 gas plays a role of an etching gas, and the N2 gas plays a role of a deposition gas. (Because aluminum nitride or boron nitride is a component of the sidewall protective film).

The experimental conditions in this example are as follows.

[Plasma Discharge Conditions] C12 / BC13 / N2 = 100/20/5 scc
m, 10 mTorr, Source Power: 80
0W Bias power: 120W, temp. Wall
/ Stage = 80 ° C./50° C. [Measurement method] Al etch rate measuring method: use of step gauge Aluminum wire width dimensional variation: Measured from SEM photograph FIG. 8 shows the in-plane distribution of Al etch rate in the second embodiment. The results are shown. The result was the same as in the first embodiment, as in condition D.
Shows the best uniformity, and the condition B has the worst uniformity. The reason is as described in the first embodiment.
However, the effect of inhibiting etching is lower in the case of N2 than in the case of CHF3, and even in the case of the condition D, the etch rate in the peripheral portion of the wafer is not so much suppressed.

FIG. 9 shows the in-plane distribution of the dimensional variation of the Al wiring width in the second embodiment. As a result, similarly to the first embodiment, the condition D shows the best dimensional controllability, and the condition A
Had the worst dimensional controllability. The reason is the same as in the first embodiment.

From the results of FIGS. 8 and 9, it can be said that the condition D is the most excellent gas introduction method even when the aluminum laminated wiring is etched with C12 / BC13 / N2 gas.

[0032]

The aluminum etching rate can be made uniform by supplying the etching gas to the center of the wafer where the etching products are large and the partial pressure of the etching gas is low. Furthermore, the deposition component is diluted,
By supplying the deposition gas from the peripheral portion of the wafer where side etching is likely to occur, highly accurate dimensional control can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a conventional apparatus.

FIG. 2 is an apparatus configuration diagram devised so that the distribution of process gas in a chamber becomes uniform.

FIGS. 3 (a) and 3 (b) are diagrams showing a relationship between a gas distribution in a chamber, an etch rate, and a dimensional variation in a conventional apparatus.

FIG. 4 is a diagram showing a distribution of an etch rate and a dimensional variation when a process gas distribution is completely uniform.

FIG. 5 is a diagram showing an ideal gas distribution in a chamber.

FIG. 6 is a graph showing an in-plane distribution of an Al etch rate in the first embodiment.

FIG. 7 is a graph showing the in-plane distribution of the variation in the dimension of the Al wiring in the first embodiment.

FIG. 8 is a graph showing a surface name distribution of an Al etch rate in the second embodiment.

FIG. 9 is a graph showing the in-plane distribution of the variation in the dimension of the Al wiring width in the second embodiment.

Claims (5)

(57) [Claims] In a dry etching apparatus for an aluminum and aluminum alloy film, a gas contributing to etching is introduced from a central portion of a chamber top plate so as to have a maximum value of the concentration at a central portion, and a gas contributing to deposition. Dry etching apparatus having a mechanism for introducing a gas from a plurality of locations on the outer periphery of the chamber so as to have a minimum value of the concentration at the center. 2. A dry etching method for an aluminum or aluminum alloy film, comprising using the dry etching apparatus according to claim 1. 3. An apparatus for manufacturing a semiconductor device, comprising the dry etching apparatus according to claim 1. 4. A method for manufacturing a semiconductor device, comprising dry-etching an aluminum or aluminum alloy film using the semiconductor device manufacturing apparatus according to claim 3. 5. A semiconductor device manufactured by the method according to claim 4.