JPH0529131B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a dry etching apparatus used for microfabrication of a workpiece such as a silicon substrate.

(Prior Art) In recent years, integrated circuits have become increasingly finer, and prototypes of ultra-LSIs with minimum pattern dimensions of 1 μm or less have recently been developed. By the way, plasma etching technology has become indispensable for this ultra-fine processing.

FIG. 5 shows a conventional plasma dry etching apparatus. 1 in the figure indicates a reaction gas introduction pipe 2 at the top,
This is a reaction vessel with gas exhaust pipes 3 connected to each side. A flat electrode (cathode) 6 is provided at the bottom of the reaction vessel 1 on which a workpiece 5 is placed via a ring-shaped insulating member 4 . This flat electrode 6
is cooled by cooling water passing through piping 7. The flat electrode 6 is connected to a high frequency power source 9 via a matching box 8. Note that 10 in the figure is an exhaust member provided in the reaction vessel 1, and is provided with holes for evenly exhausting the reaction gas.

The operation of the above device is as follows. First, the object to be processed 5 is placed on the flat electrode 6, and then a reaction gas such as CF ₄ or Cl ₂ is introduced into the reaction vessel 1 through the gas introduction tube 2 . Subsequently, by turning on the high frequency power source 9 via the matching box 8, a glow discharge is generated between the flat electrode 6 and the reaction vessel 1. As a result, positive ions are generated from the gas plasma on the flat electrode 6. The cathode drop voltage (Vdc)
The object to be processed 5 is accelerated by this, and the object to be processed 5 is subjected to etching.

By the way, in recent years, in order to achieve ultra-fine processing at the mass production level, it is necessary to improve the etching speed, anisotropic etching, increase the etching speed ratio of the mask material and base material, reduce damage to devices, control the cross-sectional shape, etc. is required. In order to solve these problems, it is essential to control the amount of reactive active species generated by dissociation of reactive gases and the ion impact energy on the processed object, that is, the cathode drop voltage (Vdc). flow rate,
This is done by devising a combination of process parameters such as gas type and gas flow.

However, according to the conventional apparatus, when the RF power is increased in order to increase the amount of reactive species produced and improve the etching rate, the workpiece 5
The upper cathode drop voltage also increases, leading to deterioration of the etching mask, reduction in etching rate ratio, and damage to the object 5 to be processed. That is, in the conventional apparatus, it is not possible to independently control the generation of reactive species and the cathode drop voltage (ion bombardment energy) on the object to be treated.

(Problems to be Solved by the Invention) The present invention was made in view of the above circumstances, and it independently controls the generation of reactive species and the cathode drop voltage to the object to be processed, thereby achieving etching required for ultra-fine processing. An object of the present invention is to provide a dry etching device that can easily improve speed.

[Structure of the Invention] (Means and Effects for Solving Problems) The present invention adds a new means to the conventional device to vary the internal volume of the cavity of the cathode and a means to measure the self-bias voltage on the cathode. The gist is that it has been added,
The cathode drop voltage can be reduced without changing the RF voltage or pressure.

(Example) An example of the present invention will be described below with reference to FIG.

21 in the figure is a reaction container. This reaction vessel 2
1 is provided with a cathode 22 and an anode 23 that constitute a part of the container 21. The cathode 22 is provided in the upper part of the reaction vessel 21 via a ring-shaped insulating member 24, and has a hollow shape having an internal space and an opening. Further, a part of the cathode 22 is constituted by a metal bellows 22a, and a discharge gap is formed between the cathode 22 and the anode 23. A driving means 25 for moving the bellows 22a up and down is connected to the bellows 22a. Similarly, a gas introduction pipe 26 is connected to the bellows 22a portion, and a second gas introduction pipe 26 is connected to the gas introduction pipe 26 to measure the cathode drop voltage (Vdc).
The illustrated circuit 27 is connected, and a high frequency power source 29 is also connected via a matching box 28. As shown in FIG. 2, this circuit 27 consists of a choke coil L, capacitors C ₁ , C ₂ , and resistors R ₁ , R ₂ , and is designed to be measured with a meter M. The anode 23 has a flat plate shape and is cooled by cooling water passing through a pipe 30. A workpiece 31 is placed on the anode 23 . In addition, 32 in the figure represents a gas exhaust pipe provided in the reaction vessel 21, and 33 represents a dark space seal. In dry etching equipment with this structure,
Since the opening of the hollow cathode 22 is opposed to the anode 23 forming a part of the reaction vessel 1 to form a discharge gap, the discharge phenomenon is significantly different from that shown in FIG. That is, in the case of Fig. 5, the part farther away from the flat electrode becomes plasma, whereas
In the case of the present invention, the inside of the cathode 22 becomes plasma and the anode 23 side becomes a dark space. Therefore,
In the case of the present invention, the object to be processed 30 is placed on the side of the anode 23 that forms part of the reaction vessel 21 .

According to the above embodiment, a part of the cathode 22 is made of a metal bellows 22a, a driving means 24 for moving the bellows 22a up and down is provided above the bellows 22a, and the cathode drop voltage is measured in the reaction vessel 21. Because it has a structure in which a circuit 27 is connected,
By lowering the bellows 22a using the driving means 25, the internal volume of the cathode 22 can be reduced. Therefore, RF power, etching pressure,
Since the cathode drop voltage can be controlled independently of the process parameter of gas flow rate, it is possible to control the amount of reactive active species produced by dissociation of the reactive gas and the ion bombardment energy to the workpiece 33, that is, the cathode drop voltage (Vdc). It can now be controlled independently, making it easier to improve the etching speed required for ultra-fine processing, improve anisotropic etching, improve the etching speed ratio between the mask material and the underlying material, reduce damage to devices, and control the cross-sectional shape. I dedicated myself to what I could achieve.

In the above embodiment, a case was described in which a part of the cathode was made into a bellows in order to vary the internal volume of the cavity of the cathode, but the present invention is not limited to this.
The structure shown in FIG. 4 may also be used. Here, FIG. 3 shows a structure in which a disk 41 slightly smaller than the cross-sectional area of the cathode 22 is provided inside the cathode 22, and this disk can be moved up and down by a driving means 25 via a support rod 42 and a vacuum seal 43. ing. On the other hand, in FIG. 4, a bellows 44 is provided between the reaction vessel 21 and the anode 23, and the anode 2
It has a structure that allows it to be moved up and down from the lower side of 3.

[Effects of the Invention] As detailed above, according to the present invention, the generation of reactive species and the cathode drop voltage on the object to be processed are independently controlled, thereby improving the etching rate, anisotropic etching,
It is possible to provide a highly reliable dry etching apparatus that can improve the etching rate ratio between the mask material and the underlying material and reduce damage to devices.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a dry etching apparatus according to one embodiment of the present invention, FIG. 2 is an explanatory diagram of a circuit used in the same apparatus, and FIGS. 3 and 4 are respectively for other embodiments of the present invention. An explanatory diagram of such a dry etching apparatus, FIG. 5 is an explanatory diagram of a conventional dry etching apparatus. 21... Reaction container, 22... Cathode, 22a, 4
4... Bellows, 23... Anode, 24... Insulating member, 25... Drive means, 26... Gas introduction pipe, 2
7...Circuit, 28...Matching box, 29
... High frequency power source, 30 ... Piping, 31 ... Processing object, 32 ... Gas exhaust pipe, 33 ... Dark space seal, 41 ... Disc.

[Claims]

1. A vacuum container having an inlet and an outlet for reactant gas, a first electrode provided in the vacuum container and on which the object to be processed is placed, and a vacuum container disposed opposite to the first electrode. a second electrode, a power supply that applies high frequency power to the first electrode, a transport mechanism that transports the workpiece to the outside of the vacuum container, and a A measuring mechanism configured to measure the temperature outside the vacuum container; and a circulator connected to the first electrode to cool the first electrode; An etching device characterized by adjusting. 2. The etching apparatus according to claim 1, wherein a contact temperature measuring device using a thermocouple or a non-contact temperature measuring device using light is used as the measuring mechanism for measuring temperature.