JPH08321489A - Method for treating surface and method for smoothing surface - Google Patents

Abstract

PURPOSE: To facilitate etching and smoothing of a workpiece, such as a semiconductor, for instance. CONSTITUTION: Edge parts E formed in a resist layer 15 and a hole pattern H are worked into radiused shapes by casting a gas cluster on the surface of the resist layer 15. Besides, only an exposed part of a workpiece is smoothed by casting the gas cluster on the workpiece wherein a resist means having the hole pattern formed is provided at a prescribed position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface processing method for etching a work piece such as a metal, a semiconductor or an insulator by using a gas cluster, and a patterning of the work piece so that only a predetermined portion of the work piece is patterned. The present invention relates to a surface smoothing method for smoothing.

[0002]

2. Description of the Related Art For example, a multilayer wiring technique is required to realize a VLSI or an integrated circuit having a three-dimensional structure. This multi-layer wiring technology requires that the electrical insulation of the upper and lower wiring layers be complete and that a good surface shape for the upper wiring metal film deposition be obtained. Therefore, in the multi-layer wiring process, for example, it is important how to make the lower layer surface a smooth flat surface and how to form the upper layer thin film as a dense film having excellent covering characteristics.

By the way, examples of the change in the completeness of electrical insulation in the above-mentioned multilayer wiring include growth of pinholes in a thin film and hillocks in a lower wiring metal film. This strongly depends on the unevenness of the surface of the underlying substrate or the lower wiring pattern. If this unevenness is emphasized too much, it is impossible to evenly deposit the upper wiring metal or even form a continuous metal thin film. Becomes Therefore, it has been considered to improve the coverage with the upper interlayer insulating layer and the upper wiring metal by, for example, tapering the edge portion of the lower wiring pattern to give an angle.

For example, FIGS. 5 (a) and 5 (b) show a simulation diagram of step coverage of an Al electrode deposited on a contact hole, but as shown in FIG. 5 (b), a circled portion is shown. If the thin film of A becomes thin, the resistance may increase and it may be damaged.
As shown in (1), the edge portion is tapered to make the thickness of the thin film substantially uniform, thereby improving the coverage.

[0005]

However, as described above, the flattening of the lower layer surface and the densification of the upper layer thin film have limitations on usable materials and processes.
Due to problems such as charge-up, it is extremely difficult to clean or etch the surface portion of the wiring metal under the patterned insulating film. Further, it is more difficult to clean and etch the bottom of the submicron diameter contact hole below the insulating film.

Further, as a method of tapering the edge portion, a bevel method (taper etching method), anodization method, lift-off method and the like are used. For example, the bevel method is difficult to apply to a fine device because the wiring width is widened only in the tapered portion. Further, in the anodizing method, the wiring material is limited to argon or the like, and the size of the wiring pattern is also limited. Similarly, the lift-off method has a complicated working process and is often restricted by working conditions. Therefore, in such a method, since the wiring material, the processing process, and the like are limited, versatility is low and it is difficult to easily perform etching.

Further, with such a processing method, it is difficult to cover the step difference in the contact hole having a submicron diameter,
Further, in the LPCVD method as a TiN film forming method, Cl is easily taken into the film and its removal is difficult.

FIG. 6 (a) is a schematic diagram showing an example in which the edge portion is not tapered, and FIG. 6 (b) is a schematic diagram showing an example in which the edge portion is tapered. In these figures, 16 is a cathode electrode and 17 is a resist layer. If the edge portion is not tapered, for example, as shown in FIG. 6A, the denseness of the film quality of the upper thin film also deteriorates near the edge portion and becomes thin. It becomes porous P and discharge or short circuit is likely to occur. Therefore, for example, as shown in FIG. 6B, the edge portion is tapered, but in this case, the tapered portion D becomes a dead space, so that the degree of integration can be improved. Was not.

[0009]

The present invention has been made to solve the above problems, and an edge formed on a workpiece by irradiating the surface of the workpiece with a gas cluster. The portion is etched to form an R shape.

Further, by irradiating the object to be processed on which the resist means having the hole pattern is arranged at a predetermined position with the gas cluster, only the exposed portion of the object to be processed is smoothed.

[0011]

According to the present invention, by irradiating a gas cluster, the edge portion of the object to be processed can be etched to perform taper processing, and the object to be processed on which resist means having a predetermined pattern is disposed. By irradiating the gas cluster from above, only a predetermined portion can be smoothed. This eliminates the need for complicated processing conditions when performing taper processing or surface smoothing, which has been conventionally performed, and makes it possible to easily perform etching regardless of the wiring material.

[0012]

Embodiments of the present invention will be described below. FIG. 1 is a diagram showing an example of the configuration of a gas cluster ion beam apparatus for generating and irradiating a gas cluster used in this embodiment. In this figure, 1 has a cluster generation chamber into which a gas such as Ar (argon) gas is injected, and adiabatically expands the injected gas into a vacuum, and the adiabatic expanded gas is ejected at supersonic speed, A cluster generating part 1a for generating a gas cluster (lumped atomic group) is a nozzle having a shape suitable for the shape of the cluster at the tip of the cluster generating part 1 and having a diameter of, for example, about 0.1 mm or less. Indicates a skimmer that shapes the gas cluster formed by ejecting from the nozzle 1b. In addition to Ar gas, for example, a rare gas,
It may be a halogen gas such as CO ₂ , N ₂ , H ₂ or Cl ₂ or other compound gas.

Denoted at 3 and 5 are an exhaust unit for discharging unnecessary gas to the outside in the cluster generation unit 1. Denoted at 4 is a vertically displaceable unit in the direction of the arrow for measuring the neutral beam amount of the gas cluster emitted from the skimmer 2. The measuring unit is shown in FIG. 1 and is lowered to the position where the gas cluster is discharged when actually performing the measurement. Reference numeral 6 denotes an ionization section in which an ionization electrode for ionizing the gas cluster generated in the cluster generation section 1 is arranged.

Reference numeral 7 is a mass separation unit for analyzing the gas clusters ionized in the ionization unit 6 to remove the monomers and allowing only the polymer to pass, and 8 is an exhaust unit for exhausting the monomers removed by the mass separation unit 7. Show. Reference numeral 9 denotes a monitor unit that monitors the ion dose amount of the gas cluster ion beam that has passed through the mass separation unit 7. Like the measurement unit 4, it is arranged so that it can be moved up and down in the direction of the arrow. It is designed to rise to the position where the beam passes. Then, the ion dose amount monitored here is set to, for example, about 1 × 10 ¹⁵ ions / cm ² .

Reference numeral 10 denotes an accelerating tube section in which an accelerating electrode for accelerating a gas cluster which has been ionized and sent out through each of the above-mentioned sections is arranged. Reference numeral 12 denotes an exhaust unit, and 13 denotes an irradiation unit on which a workpiece to be irradiated with ionized gas clusters, such as a metal, a semiconductor, or an insulator, is arranged.

Next, description will be made on a case where the gas cluster ion beam apparatus shown in FIG. 1 is used to etch a resist layer of, for example, a semiconductor to be processed. Figure 2
2 (a) and 2 (b) are schematic diagrams showing in cross section a hole pattern etched by irradiating a gas cluster ion beam. FIG. 2 (a) shows before irradiation and FIG. 2 (b) shows after irradiation. Shows. In these figures, 14 is a cathode electrode made of, for example, an Nb layer, 15 is a resist layer, and H is a hole pattern formed in the resist layer 15.

When the gas cluster ion beam is irradiated as shown by the arrow in the state shown in FIG. 2A, the resist layer 15 and the vicinity of the edge portion E of the hole pattern H are affected by the gas cluster ion beam. It was found that it was etched and then processed into an R shape, for example, as shown in FIG. This indicates that the vicinity of the edge portion E was particularly etched due to the extremely strong sputtering as compared with the argon monomer, for example. That is, etching can be easily performed by irradiating the gas cluster ion beam with the gas cluster ion beam apparatus shown in FIG. This etched portion can be made to have a predetermined inclination by controlling the irradiation time of the gas cluster ion beam and the ion dose amount.

By irradiating the gas cluster ion beam as shown in this figure, the edge portion E can be processed into the R shape, so that the conventional example shown in FIG.
The dead space D described in 1 above does not occur, and the degree of integration can be improved. Similarly, when the resist layer 15 is a metal electrode, the edge portion can be processed more effectively by changing the gas species. When the gas cluster ion beam is irradiated, the hole pattern H
Of the cathode electrode 14, that is, a part of the surface layer of the cathode electrode 14 is smoothed and densified, which will be described with reference to FIG.

The etching according to the method described in this embodiment is performed in a field emission display (FED), for example, in order to prevent the discharge from the anode due to the protruding portion of the gate end, the protruding portion of the gate end is rounded. Can be used for processing. In this case, etching can be performed without leaving unnecessary contamination (dirt). Further, it is possible to improve the step coverage in the submicron diameter contact hole in the VLSI device. Furthermore, due to poor step coverage when forming a multilayer wiring in, for example, a VLSI or a three-dimensional integrated circuit,
It becomes possible to reduce defects such as hillocks, voids, microcracks, and wire breakages.

Next, the hole pattern H of the resist layer 15 is formed by the gas cluster ion beam apparatus shown in FIG.
The smoothing of the bottom portion, that is, the cathode electrode 14 (Nb layer) will be described. 3 (a) and 3 (b) are schematic views showing the hole pattern H in a sectional view, and FIG. 3 (a) shows a state in which a resist layer 15 is arranged and a gas cluster ion beam is irradiated, and FIG. ) Indicates a state in which the resist layer 15 is removed after the irradiation.

For example, as shown in FIG.
The irradiated gas cluster ion beam is applied to the resist layer 15
When reaching the bottom of the hole pattern H, that is, the surface layer of the cathode electrode 14, the crystal of the surface layer is etched and jumps to the outside of the hole pattern H as indicated by the arrow, and redeposits on the resist layer 15. Come to do. That is, as a result, only the bottom of the hole pattern H is smoothed and densified. Then, by peeling the resist layer 15 from the cathode electrode 14, the cathode electrode 14 having a smooth portion Hr in which a predetermined portion has a different grain size is formed, for example, as shown in FIG. 3B.

FIG. 4 is an enlarged perspective view of a smoothed portion surrounded by a circle B in FIG. 3 (b). The part shown in the approximate center of this figure is the part irradiated with the gas cluster ion beam, and the part shown in the periphery of this central part is the part not covered by the resist layer 15 and not irradiated. . As shown in the figure, the grain size of the central portion, that is, the smoothed portion is smaller, and the unevenness is smaller than that of the peripheral portion. And actually, the resist layer 1
The positions corresponding to the hole patterns H patterned in No. 5 are selectively smoothed. Therefore, in the cathode electrode 14, the portion to be smoothed is patterned on the resist layer 15 in advance, and by irradiating the gas cluster ion beam from above the resist layer 15, only the exposed portion of the surface of the cathode electrode 14 is smoothed. You will be able to.

By irradiating the gas cluster ion beam, it is possible to smooth a specific portion of the surface of the inorganic insulating film even when the wiring material such as argon has a low melting point. In addition, the leakage current can be prevented and the characteristics can be improved by the underlying process before forming the gate wiring in the MOS device.

[0024]

As described above, according to the present invention, the gas cluster ion beam apparatus can be used for, for example, metal, semiconductor,
By irradiating an object to be processed such as an insulator with a gas cluster ion beam, the edge portion of the resist layer can be tapered. Therefore, for example, complicated processing conditions when performing taper processing by a bevel method or the like which has been conventionally performed are unnecessary, etching can be easily performed regardless of the wiring material, and unnecessary contamination of a workpiece or Damage is reduced.

Further, for example, etching of a specific minute region is performed on the surface layer of an object to be processed such as a metal, a semiconductor or an insulator by patterning with an organic film such as a resist layer or patterning of an inorganic film or a metal film. Alternatively, surface polishing and smoothing can be performed. Further, for example, it becomes possible to perform surface cleaning and etching of the contact portion in the VLSI element. Further, even when the melting point of the wiring material such as argon is low, it is possible to smooth a specific portion of the surface of the inorganic insulating film. In addition, the leakage current can be prevented and the characteristics can be improved by the underlying process before forming the gate wiring in the MOS device.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a gas cluster ion beam device used in an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example in which an edge portion of a resist layer is tapered by a gas cluster ion beam device.

FIG. 3 is a diagram illustrating an example of smoothing only a predetermined portion of a cathode electrode by a gas cluster ion beam device.

FIG. 4 is a view showing a part of a cathode electrode smoothed by a gas cluster ion beam device.

FIG. 5 is a diagram showing step coverage of an Al electrode deposited on a contact hole.

FIG. 6 is a diagram schematically showing a conventional example in which an edge portion of a resist layer is not tapered, and a conventional example in which an edge portion is tapered.

[Explanation of symbols]

 1 cluster generation part 6 ionization part 7 mass separation part 13 irradiation part 14 cathode electrode 15 resist layer

Claims (2)

[Claims] 1. A surface processing method comprising irradiating a gas cluster on the surface of a workpiece to etch an edge portion formed on the workpiece to form an R shape. 2. Smoothing only the exposed surface of the object to be processed by irradiating the object to be processed on which the resist means having the hole pattern formed at a predetermined position is irradiated with a gas cluster. A surface smoothing method characterized by: