JPS6345468B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a reactive ion etching apparatus, and is particularly used in semiconductor manufacturing equipment.

(Prior art) In recent years, with the transition from integrated circuits (ICs) to large-scale integrated circuits (LSIs), the integration of elements has increased,
Speeding up is being done. Microfabrication technology is required to achieve higher integration and higher speed of devices.
Wet etching and chemical dry etching, which were conventionally used in the manufacturing process of large-scale integrated circuits,
Instead of isotropic etching, reactive ion etching (RIE), which allows anisotropic etching without so-called side etching, has been adopted.

That is, as shown in FIG. 3, a parallel plate type reactive ion etching apparatus is used, for example. This reactive ion etching apparatus consists of a lower electrode 16 on which an object to be etched 15, such as a silicon wafer, is placed in a reaction chamber 12 filled with a predetermined reaction gas 11, and an opposing electrode 16 disposed oppositely to the lower electrode 16 with a predetermined distance therebetween. It has an upper electrode 13. Then, a predetermined radio frequency power (RF) is applied between both electrodes 13 and 16 from a radio frequency power supply 18 via a blocking capacitor 17 to turn the reaction gas 11 into plasma. At this time, the difference in mobility between electrons and ions and the lower electrode 16 to which high-frequency power was applied are determined.
and a counter electrode 13 and a grounded chamber 12
A negative self-bias occurs due to the difference in the area of the inner wall. Negative self-bias is called cathode drop voltage and is measured from ground potential and is expressed as Vdc. Due to this negative self-bias, positive ions generated in the plasma are accelerated and collide perpendicularly with the surface of the object to be etched 15 on which etching species are adsorbed. The collided positive ions are etched species and etched object 1
5 to generate volatile substances, which are exhausted from the exhaust pipe 19 to advance etching. In other words, in order to perform a uniform etching process, the distribution of positive ions generated in the plasma must be made uniform. This distribution is determined by the flow 110 of the reactant gas in the chamber shown in FIG.
In the conventional apparatus, the flow rate of the reaction gas 11 is controlled by a reaction gas flow rate controller 111, and the reaction gas 11 is introduced into the chamber 12 from the reaction gas introduction hole 14 through the introduction pipe 112.
It was impossible to control 10.

Figure 4 shows an improved version of this. In FIG. 4, parts that are the same as those in FIG. 3 are given the same reference numerals, and their explanation will be omitted. That is, the grounded pair upper electrode 23 is processed to be hollow, the reactive gas 11 is introduced into the electrode 23, and the chamber 1 is introduced through a large number of reactive gas introduction holes 24 formed on the surface of the electrode 23.
A reaction gas 11 is introduced into the reactor 2. 29 is a gas exhaust pipe.

As a result, the flow distribution of the reactant gas 11 becomes somewhat more uniform in the case of FIG. 4 than in the case of FIG. 3, and as a result, the distribution of positive ions generated in the plasma can be made uniform. It's becoming like that.

However, in the case of FIG. 4, the hole diameter of the reaction gas introduction hole 24 is fixed, so the gas flow is uniform only when the conditions of a certain gas flow rate and a certain gas exhaust speed are maintained. However, if the above conditions change, the distribution of gas flow immediately becomes non-uniform, and the distribution of positive ions generated in the plasma also becomes non-uniform. As a result, non-uniform etching occurs.

Even in the conventional improved apparatus shown in FIG. 4, there is no controllability of gas flow distribution, and etching is inevitably non-uniform depending on the etching conditions.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned problem that the distribution of the reaction gas flow becomes non-uniform, resulting in non-uniform etching, and constantly controls the distribution of the reaction gas flow. ,
It is an object of the present invention to provide a reactive ion etching device that enables uniform etching processing by uniformly distributing positive ions generated in plasma.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, a plurality of gas introduction paths are connected to a plurality of gas introduction holes in the reaction chamber, and the gas flow rate flowing through each gas introduction path is controlled. It is equipped with a gas flow rate controller that can control each independently.

(Function) By the above means, the flow of the reaction gas is controlled separately and independently into a plurality of systems, the distribution of the flow of the reaction gas within the chamber is controlled, and uniform etching processing is made possible.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of one embodiment of the present invention.
In the figure, reference numeral 32 denotes a reaction chamber filled with a predetermined reaction gas, which is exhausted through a gas exhaust pipe 39, and the interior of the chamber 32 is maintained at a predetermined reduced pressure. Inside the chamber 32, an upper electrode 33 and a lower electrode 36, which are a pair of parallel plate electrodes, are installed. The upper electrode 33 has a hollow structure inside as shown in FIG. 2, and therein is a concentric upper electrode partition plate 41, which divides the electrode into four chambers. A large number of reaction gas introduction holes 34 are formed in the lower surface (discharge surface) of the upper electrode 33, and the reaction gas 31 is introduced into the chamber 32 through these holes 34. Arrow 310 indicates the direction of flow of reactant gas within the chamber.

The reaction gas 31 is usually a mixed gas of two to three types (a mixed gas of simple gases A, B, and C shown at 313 in the figure).
Use. This reaction gas 31 is separated into four paths and controlled by four reaction gas flow rate controllers 311. Gas introduction route 3 consisting of four pipes
12 into the four chambers in the upper electrode 33 shown above. An object to be etched 35, such as a silicon wafer, is placed on the lower electrode . Further, a high frequency power source 38 is connected to the lower electrode 36 via a blocking capacitor 37. Further, the wall surface of the chamber 32 and the upper electrode 33 are electrically grounded.

When performing etching using such a reactive ion etching device, the chamber 32
The flow distribution of the reactant gases shown by arrows 310 within the reactor gas can be changed by adjusting the flow rates of each of the four flow rate controllers 311.

FIGS. 5a and 5b show the distribution of etching rates when etching is performed using a conventional etching apparatus as shown in FIG. A is for a low pressure condition, and b is for a high pressure condition. In both cases, the etching rate is abnormally faster at the periphery (75 cm or -75 cm) than at the center (0 cm) of the wafer. FIGS. 5c and 5d show the distribution of etching rates when etching is performed using a conventional etching apparatus as shown in FIG. c is for low pressure conditions, and d is for high pressure conditions. In case c, the distribution of the reactant gas inside the chamber is made uniform, and the distribution of the etching rate is also made uniform, but when the conditions are changed to the high pressure side, the uniformity of the flow distribution of the reactant gas deteriorates, and the etching rate in the periphery becomes more uniform. The speed has increased abnormally.

FIGS. 5e and 5f show the results of etching using the etching apparatus shown in FIG. 1, where e is a low pressure condition and f is a high pressure condition.

It can be seen that uniform etching can be achieved in both cases e and f. In the case of e, the flow rate ratio of the four reaction gas flow rate controllers is maintained at 1:1:1:1, but in the case of f, the flow rate ratio is set to 1.2:1.1:1.0:0.8, and the flow rate in the central part is kept at 1:1:1:1. This is because adjustments were made to increase the amount.

[Effects of the Invention] As described above, according to the present invention, the flow of the reactant gas is controlled separately and independently into multiple systems, the flow distribution of the reactant gas within the chamber is controlled, and the positive energy generated in the plasma is controlled. It is possible to provide a reactive ion and etching device that enables uniform etching processing by making the distribution of ions uniform.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing one embodiment of the present invention, FIG. 2 is a partially cutaway perspective view showing an example of the upper electrode in FIG. 1, and FIGS. A schematic cross-sectional view showing an ion etching apparatus, and FIG. 5 shows the distribution of etching speed within the wafer plane when a silicon wafer is etched using the reactive ion etching apparatus shown in FIG. 1, FIG. 3, or FIG. 4. FIG. 31... Reaction gas, 32... Reaction chamber,
33... Upper electrode, 34... Reactive gas introduction hole, 3
6... Lower electrode, 37... Blocking capacitor, 38... High frequency power supply, 39... Gas exhaust pipe, 311... Reaction gas flow rate controller, 312...
Gas introduction route.

Claims (1)

[Scope of Claims] 1. Reactive ion etching in which a reactive gas is introduced into a reaction chamber, and high frequency power is applied to an electrode provided in the reaction chamber to turn the reactive gas into plasma to etch the material to be etched. The apparatus is characterized by comprising a plurality of gas introduction paths connected to a plurality of gas introduction holes in the reaction chamber, and a gas flow rate controller that can independently control the gas flow rate flowing through each of the gas introduction paths. Reactive ion etching equipment. 2. Parallel plate electrodes facing each other are used as electrodes, a plurality of gas introduction holes are provided on one discharge surface of the parallel plate electrode, and each gas introduction hole is connected to a plurality of gas introduction paths. A reactive ion etching apparatus according to claim 1. 3. The reactive ion etching apparatus according to claim 1, characterized in that a reaction gas that is a mixture of a plurality of single gases is used as the reaction gas, and the reaction gas is divided into a plurality of gas introduction paths.