JPS61145846A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To bury simply a through hole with electrode material according to the depth of the hole and to reduce surface step difference after the burying of the hole, by utilizing focused ion beam deposition in a process for burying the though hole with the electrode material. CONSTITUTION:Focused ion beam deposition is a method that can ionize material, that is, electrode material in a vacuum or under a low gas pressure, focus the ion beam with an electromagnetic lens and irradiate it selectively on a semiconductor substrate to be deposited. Since the focused ion beam deposition can freely alter energy focusing density and set selectively it, range, speed and thickness, etc., of electrode material deposition can be arbitrarily controlled. Accordingly, by applying the focused ion beam deposition, energy focusing density and irradiation time of the ion beam can be controlled to bury a through hole with electrode material flatly according to the depth and area of the hole.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and in particular to a method for forming contacts between upper and lower layer circuit elements in multilayer three-dimensional semiconductor circuit elements. This is related to.

[Conventional technology]

FIG. 3 shows a schematic configuration of a conventional two-layer semiconductor circuit device of this type. In the configuration shown in FIG. 3 is an N-type semiconductor layer which becomes a source region, 4 is an N-type semiconductor layer which becomes a drain region, 5 is a gate electrode, and together with a wiring material layer (for example, doped polysilicon M) 6, as shown in FIG. NO;)
It forms a lower layer circuit element A as a transistor.

Further, 7 is an interlayer insulating film (for example, SiO□M), 8 is an insulating oxide film, 8 is a P-type silicon semiconductor layer, 10 is an N-type semiconductor layer that becomes a source region, and 11 is an N-type semiconductor that becomes a drain region. The layer 12 is a gate electrode, and the wiring material layer (
For example, Al1. fi) Together with 13, similarly NO9) forms an upper layer circuit element as a transistor, and between each wiring material layer Ill, 13 is an interlayer insulating film 7.
A conductive material layer 15 buried through a through hole 14 is connected to a wiring material layer portion 13a through a contact hole 1B to the conductive material layer 15.

In the case of this conventional configuration, the lower layer circuit element A is formed and then the interlayer insulation lI! 7 is formed and planarized, then the upper layer circuit element B is formed, and then R
A through hole 14 reaching the wiring material layer 6 is deeply formed in the interlayer insulating film 7, a conductive material layer 15 is buried in the through hole 14 and connected and patterned, and then an insulating oxide film 8 is formed.
At the same time, a shallow contact hole 1B is formed in this insulating oxide W18, and a wiring material layer 13 is further deposited.
In addition, the contact hole IB is embedded and connected in the wiring material layer portion 13a.

[Problem that the invention seeks to solve]

However, in the case of such a conventional method, in order to make through-hole contact between each circuit element in the upper layer and the lower layer, on the one hand, it is necessary to bury the deeply drilled through hole by depositing a conductive material layer and pattern it. This increases the number of manufacturing steps by requiring a photolithography process followed by an etching process, and on the other hand, the connection of the conductive material layer to this deep through hole requires different deposition conditions, i.e., a relatively shallow contact hole. The wiring material layer must be connected by the deposition of the conductive material layer, and since the former conductive material layer is deposited to a uniform thickness, as shown in Fig. 4, the upper part of the through hole is The conductive material layer has various problems, such as the thickness of the conductive material layer, which remains as a surface step after etching.

This invention method was made to improve these conventional problems, and its purpose is to:
For example, through-holes, which are required in multi-layer three-dimensional semiconductor circuit elements, have a depth that varies greatly depending on the location, and are filled with electrode material in accordance with the depth of the hole. It is an object of the present invention to provide a method for manufacturing a semiconductor device that not only simplifies its formation, but also reduces surface steps after formation.

[Means for solving problems]

In the method of this invention, a focused ion beam deposition method is used in the process of filling the through holes with electrode material.

This focused ion beam deposition technology ionizes a substance, here the electrode material, in vacuum or under low gas pressure, and focuses this atomic ion beam using an electromagnetic lens to selectively deposit it onto a semiconductor substrate. The electrode material can be deposited by irradiating the electrode material, and the energy concentration density can be freely changed and set, so it has the advantage that the range, speed, thickness, etc. for electrode material deposition can be controlled arbitrarily. and is suitable for depositing this type of electrode material. By the way, regarding this focused ion beam deposition, please refer to the explanatory article r Toshiyoshi Takagi/Applied Physics, U.

P, 1070-(1972) J.

[For production]

Therefore, in the method of the present invention, by applying this focused ion beam deposition method, it is possible to selectively deposit a thick electrode material only in the deep portion of the hole of the through-hole contact. In other words, by controlling the energy focus density and irradiation time of the ion beam, it is possible to embed the electrode material in a manner that corresponds to the depth and width of the contact hole and that the surface after deposition is flat. .

〔Example〕

An embodiment of the method for manufacturing a semiconductor device according to the present invention will be described in detail below with reference to FIGS. 1 and 2.

FIG. 1 is a sectional view showing a schematic structure of a two-layer semiconductor circuit device to which this embodiment method is applied, corresponding to the conventional method shown in FIG. 3. In each of these figures, the same reference numerals indicate the same or corresponding parts, and in this embodiment method, each of the upper layer and lower layer circuit elements A and B in the conventional method
Instead of embedding the through holes 14 by depositing a layer of conductive material 15 for contact between the underlying circuit elements A
The connection of the wiring material layer 13 of the circuit element B in the upper layer to the wiring material layer 6 of the conductive material layer is buried and deposited in the through hole 14 by the focused ion beam deposition method.
7.

As previously described in detail in connection with the prior art method, the depth of the hole in which the electrode material must be buried and deposited for the contact differs from part to part. In other words, the contact hole for obtaining the potential in the lower layer circuit element A is deep, whereas the upper layer circuit element B
The contact hole for obtaining the potential at is shallow.

Therefore, in the method of this embodiment, a focused ion beam deposition method is used for this purpose, and the oxide is deposited thickly in deep holes and relatively thinly in shallow holes. In other words, by controlling the embedding of the electrode material into the contact hole in this way, as shown in Figure 2, 1.
This electrode material can be easily and easily deposited with surface steps sufficiently suppressed. Furthermore, in this case, unlike the conventional method, there is no need for complicated means such as a photolithography process and an accompanying etching process, and there is no need for patterning for electrode formation.
For example, this focused ion beam has a beam diameter of 0.1 pm.
Since the irradiation position can be controlled to within a range of ±0.5 mm, it is even possible to deposit electrode material only inside a through hole having a diameter of 2 to 3 mm or more.

In the above embodiment method, a two-layer structure semiconductor circuit device was described, but in the case of a multilayer structure of three or more layers, the difference in the depth of the through hole depending on the location becomes even larger. is even more effective.

〔Effect of the invention〕

As detailed above, according to the method of the present invention, the focused ion beam deposition method is applied to the buried deposition of electrode material in the through-hole contact portion of a semiconductor device, and the electrode material is deposited in accordance with the depth of the contact hole. Since the deposition rate of the material can be selected and set, a series of complicated steps such as photolithography can be omitted, and the surface level difference after electrode deposition can be effectively reduced.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the general structure of a two-layer semiconductor circuit device to which an embodiment of the method of the present invention is applied. FIG. 2 is an explanatory cross-sectional view showing the state of buried and deposited electrode material in the through-hole contact portion of the above, FIG. 3 is a cross-sectional view showing the general structure of the above device to which the conventional method is applied, and FIG. FIG. 3 is an explanatory cross-sectional view showing a state in which electrode material is buried and deposited in a through-hole contact portion same as the above. 1... Silicon semiconductor substrate, 2a, 2b...
- Field oxide film, insulating oxide film, A...lower layer circuit element. 6... Wiring material layer of lower layer circuit element, 7... Interlayer insulating film, 8... Insulating oxide film, 9... Silicon semiconductor layer, B... Upper layer circuit element, 13 ...Wiring material layer of upper layer circuit element, 14...Through hole, 17
...A conductive material layer deposited by focused ion beam deposition.

Claims (1)

[Claims] A method for manufacturing a semiconductor device, which is used to manufacture a multilayer three-dimensional semiconductor circuit element, and the method comprises embedding and depositing an electrode material into a through-hole contact hole by a focused ion beam deposition method.