JPH02244633A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form a highly reliable connection structure regardless of the thickness of an insulating material layer by a method wherein a connecting hole is opened in the insulating material layer interposed between conductors with a focused ion beam and the hole is filled with a metal layer by a deposition treatment using a focused ion beam. CONSTITUTION:An SiO2 insulating film 2, a PSG layer 3, an Al layer 6 which is a lower wiring layer and a PSG layer 5 are formed on an Si substrate 1. A focused ion beam (an FIB) is irradiated on part of the surface of the layer 5 to open a connecting hole 7 and when the hole 7 reaches the surface of the layer 6, a perforating treatment is stopped. Then, W(CO)4 is introduced in a treating chamber and when Ga<+> ions of the FIB are irradiated on the hole 7, a reduced W layer (an interlayer connecting layer) 8 is filled in the hole 7. Then, an Al layer 9 is applied and is patterned to form an upper wiring layer.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a processing method for connecting conductors to each other through an insulating material layer interposed between the conductors, such as a glabella connection in multilayer wiring, and the thickness of the insulating material layer Regardless, the purpose of this study is to provide a processing method for forming a highly reliable connection structure in a microscopic region, by making a connection hole in an insulating material layer interposed between conductors using a focused ion beam, and filling the hole with a focused ion beam. The structure includes filling with metal by a beam-based deposition process.

(Industrial Application Field) The present invention relates to a method for forming a connection electrode structure such as an interlayer connection in a semiconductor integrated circuit (IC), and particularly relates to a processing method for forming an interlayer connection electrode in a minute area using a focused ion beam. .

Semiconductor ICs are becoming increasingly highly integrated and miniaturized,
Accordingly, the problem of how to form glabellar connections in multilayer wiring has become important. This is because even though the area that can be used for connecting between the eyebrows has become smaller, the thickness of the insulating layer does not decrease much, so the aspect ratio of the connection hole increases, and the connection hole has to be filled to prevent breakage. However, this is due to the fact that it has become difficult to form upper layer wiring. This situation is the same when contact electrodes are formed on elements built into a semiconductor substrate.

If the aspect ratio of the connection hole is small, that is, if the depth is small compared to the opening size, connection with the lower layer wiring can be made by drilling the connection hole in the insulating layer and forming the upper layer wiring by a method such as vapor deposition. It's done. On the other hand, if the opening size is small and the aspect ratio is large, if the conductive material is deposited using a method that does not provide sufficient coverage, it will become discontinuous at the hole bottom or shoulder.
It will not function as a connection electrode.

For this reason, we added the process of depositing a conductive material using a process that provides good coverage, etch-banking it and leaving the conductive material only inside the contact hole, and then forming the upper layer wiring after filling the contact hole. things are being done.

As this connection hole filling process, a combination of low pressure CVD and RIE, selective growth of tungsten (W), etc. are known, but all of them require a long process time and still have the problem of reduced throughput.

Therefore, if a connecting hole filling technique that is easy to work with and does not cause a drop in throughput could be provided, it would greatly contribute to higher integration of ICs.

C. Prior art and problems to be solved by the invention] In recent years, focused ion beams,
A technology utilizing FIB (hereinafter abbreviated as FIB) has been developed, and apparatuses for selective ion implantation and ion beam etching have been put into practical use. Ion beam etching using FIB allows selective etching in units of 0.1 μm, and because the anisotropy of etching is remarkable, it is possible to drill submicron connection holes at precisely selected positions. is possible.

However, a process for selectively filling such a small connection hole with a large aspect ratio with a metal material has not been known in the past, and an interlayer connection body has not been formed by FIB.

An object of the present invention is to provide a processing method for opening micro connection holes using FIB and filling the connection holes using FIB, and to provide an IC in which interlayer connections are formed in finer areas. That's true.

[Failure to solve the problem]

- In order to achieve this, the method for manufacturing a semiconductor device of the present invention includes a step of selectively irradiating an insulating material layer covering the surface of a conductor to be connected with a focused ion beam to form a contact hole; and a step of supplying a metal compound in a vapor phase while irradiating the connection hole with an ion beam, and depositing a metal constituting the compound in the connection hole, which is the irradiation position.

That is, to describe a typical processing step that is a feature of the present invention, a connection hole is opened in the glabella insulating layer using FIB, and the hole is filled with metal reduced by FIB irradiation. .

[Function] An organic compound of a metal, such as W (Co), is reduced by the energy of the FIB, and a simple metal (W) is precipitated.

This reduction reaction progresses when the metal surface is exposed to FIB irradiation, so if FIB is fixedly irradiated at the perforation position and organic metal vapor is supplied, the metal will deposit in the drilled hole and form the interlayer connection hole. Filling is carried out.

The work accuracy is on the same level as FIB irradiation position control, so
It is easy to make an extremely small connection hole in a micro area and then irradiate the hole position again with FIB, making it possible to fill the minute connection hole with the reduced metal.

〔Example〕

FIG. 1 is a schematic cross-sectional view showing the steps of an embodiment of the present invention. The following description will be given with reference to the drawings.

The figure (a) shows a state in which a glabella insulating film is provided on the lower layer wiring. In the figure, 1 is a Si substrate, and 2 is a lower layer wiring. Layer 1, 3 and 5 are 230 layers, and 4 is 5oc4 coated to flatten the surface. Such structures are commonly found in conventional IC forming processes.

FIB is irradiated to the position where the connection with the upper layer wiring is to be made as shown in the figure (g)) to open the connection hole 6.

The thickness of the PSG is about 1 μm, and the opening is, for example, 1.0 μm×1. , a hole of 0 μm is drilled. The processing conditions are, for example, the ions used are Ga'' and the drilling target is PSG.
In this case, the accelerating voltage is 30 KeV and the pressure is 0.
1 to 0.2 Torr. Beam current is 400pA
It is. Since the progress of drilling can be known by observing the emitted secondary electrons, the drilling process is stopped after confirming that the secondary electrons have reached the /IJI surface.

A large number of such connection holes are provided in one IC chip, but in this example, all necessary connection holes are opened for each wafer set in the FIB comparison device before the next filling process. shall proceed to. Of course, it is also possible to repeat drilling and filling at each treatment location.

Next, W(CO)6 is introduced into the processing chamber at a pressure of 10-'-10-'Torr, and Ga'' ions are irradiated at 30 KeV by aligning the irradiation position of the FIB with one of the connection holes.
The decomposition of W(Co)6 progresses on the A1 plane or the W plane at the bottom of the hole, and the reduced W is deposited in the hole, so that the connecting hole is filled with W as shown in FIG.

When one connection hole is filled, the next connection hole is irradiated with FIB and filled with W in the same way, and when all the connection holes in the wafer are filled, the next wafer is drilled and filled. I do.

Next, an Affi layer 8, which will become a (1)-layer wiring, is deposited by vapor deposition or sputtering, and patterned to form an upper layer wiring. This state is shown in figure (d), where 7 is the glabella connection of W.

The present invention can also be applied to connection electrodes of various elements, for example, to the formation of ohmic contacts of transistors.

In that case as well, the completion of the drilling can be determined by observing secondary electrons, so that even with a shallow emitter, a contact can be reliably formed without destroying the junction.

〔Effect of the invention〕

As explained above, according to the method of the present invention, glabellar connections can be reliably formed in minute areas, making it possible to achieve high integration of ICs.

[Brief explanation of drawings]

FIGS. 1(a) to 1(a) are schematic cross-sectional views showing the steps of the example, in which 1 is a Si substrate, 2 is a 5iOz film, 3.5 is a PSG layer, 4 is a SOG layer, 6 is the A1 layer of the lower layer wiring, 7 is the connection hole, 8 is W which is the connection between the eyebrows, and 9 is the A1 layer of the upper layer wiring.

Claims (1)

[Claims] A step of forming a connection hole by selectively irradiating an insulating material layer covering the surface of a conductor to be connected with a focused ion beam, and forming a gas phase while irradiating the connection hole with an ion beam. A method for manufacturing a semiconductor device, comprising the steps of: supplying a metal compound; and depositing a metal constituting the compound into the connection hole, which is the irradiation position.