JPS6348838A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form a fuse element in a semiconductor substrate, on which an LSI circuit is formed, without providing an area, by alloying a junction part of the substrate and an Al wiring, i.e., the junction part of an Al/Si n<+> layer, forming an Al.Si p-type layer, forming a p-n junction, and providing a non- conductive insulated layer of the Al wiring. CONSTITUTION:Laser pulses 17 are projected on a contact hole part. Al in the contact hole part is fused by heating with the laser pulses. The junction part of Al/Si is made to be alloy, and an Al.Si alloy layers 15 are formed. In the alloying work, excimer laser pulses are projected. Since the p-type alloy layer is formed in the n<+> junction part of an n<+> type layer of Al/Si, a current, which flows in the direction of an arrow II, is stopped by the Al.Si alloy layer 15 on the right. A current in the opposite direction is stopped by the left alloy layer 15. Therefore, an Al wiring 14 becomes a non-conductive insulated state. The device shown in the Figure is operated as a fuse element.

Description

Detailed Description of the Invention [Summary] In order to form a fuse element for a semiconductor device, a contact hole is formed in an insulating layer on the surface of a p-type silicon substrate, and this contact hole is filled with aluminum (i). /Si In making the joint, A/ /Si
(n” 1m) alloy the junction to form a p-type layer,
Create an insulated (non-conducting) state by creating a p-n junction.

C. Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor device, and more specifically, to a method for forming a fuse element by alloying the joint between aluminum (A7) and a semiconductor substrate (silicon substrate). It is.

[Conventional technology]

In an SI such as a D-RAM, a polycrystalline silicon (polysilicon) fuse is installed to perform disconnection within a redundant circuit. Referring to FIG. 2, 21 is a selection (switching) transistor, 22 is a fuse, and 23 is a selection (switching) transistor.
is a redundant circuit. Tests are performed during LSI manufacturing, and if a defective part is found, it is connected to a redundant circuit, and if the test results are perfect, the redundant circuit is disconnected. To do this, switch transistors,
Cut the fuse to the redundant circuit by applying a large current.

A conventional fuse is shown in the plan view of FIG. 3, where 24 is a polysilicon fuse and 25 is an aluminum (82) wiring layer that connects the transistor and the redundant circuit. To cut the fuse shown in the figure, a large current is applied to the Aβ wiring Ji 25 to melt the narrowed portion 24a of the polysilicon fuse 24 and burn it out, cutting the connection between the Ae wiring layers 25 (insulating do).

[Problem that the invention seeks to solve]

As shown in Figure 3, conventional polysilicon fuses have a planar configuration, which hinders the integration of LSIs and complicates the process for forming fuses in LSIs. There is.

The present invention was created in view of these points, and the LS
It is an object of the present invention to provide a method for manufacturing a fuse element used for cutting a redundant circuit of an I in a semiconductor substrate on which an LSI circuit is formed, without taking up a large area as in the conventional example.

[Means for solving problems]

1 fa) and [bl are cross-sectional views of the embodiment of the present invention, in which 11 is a p-type silicon (Si) substrate, 12 is an n+-type layer formed in the silicon substrate 11, and 13 is an insulating film ( SiO
2 membranes), 14 is A7! It's the wiring.

In the present invention, the contact hole 16 in which the entire SiO2 film 13 is formed is filled with one wiring 14, and the substrate and A7! The joint part of the wiring, i.e. 8jf/
5t (n+ type layer) is alloyed as shown in Figure 1 (bl) to form a p-type layer 15 of A7!Si, create a p-n junction (junction), and insulate the Al wiring 14. (non-conducting) state.

[Effect]

In the state shown in Figure 1(a), current can flow in the direction of the arrow ■ and in the opposite direction, and is in a conductive state.
When a p-type Al-Si alloy layer 15 is formed at the AJ/Si junction, the current indicated by the arrow ■ in Fig. 1fb) is blocked by the alloy layer 15 due to a barrier formed at the n-p junction, and becomes non-current. A similar phenomenon occurs in the contact hole on the opposite side when the contact hole becomes conductive and current flows in the opposite direction to that described above.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

First, referring to FIG. 1 (al), a p-type silicon substrate 11
The n+ type layer 12 is formed using a technique known in the art, and the silicon substrate 11 is
For example, a 1 μm thick SiO2 film 13 is opened on top of the SiO2 film 13, and then a tact hole 16 is opened in the SiO2 film 13, and
Subsequently, the A1 wiring 14 having a thickness of, for example, 1 μm is formed into the n+ type layer 1.
Patterning is performed so that conduction occurs through step 2.

In this state, current can flow in the direction of arrow 1 or in the opposite direction.

Next, as shown in FIG. 1 (bl), the contact hole area is irradiated with a laser pulse 17.Continuous wave (CW) laser beam is not used because the β wiring 14 may be peeled off when irradiated with it. AA in the contact hole area is melted by the heating of the laser pulse, and the Al/Si
The joint portion is alloyed to form the ^1si alloy layer 15. This alloying requires a laser that emits light with a high Al absorption coefficient, and in order to prevent the alloy layer 15 from becoming too deep and penetrating the n+ layer 12, the power must be set to about 5 J/c, for example. , n' are irradiated with ArF excimer laser pulses. Aj' is a trivalent element in the periodic table of elements, so Ajl! The Si alloy layer 15 becomes a p-type Si layer.

This alloy layer 15 spreads not only within the substrate 11 but also into the Al of the joint.

As a result of the formation of a p-type alloy layer at the A//5i (n+ type layer) junction, the current flowing in the direction of arrow Since the current in the direction is stopped by the alloy layer 15 on the left side of the figure, the A/wiring 14
is in a non-conducting, insulating state, and the illustrated device acts as a fuse element.

Selectively heating the i-wire in the contact hole region as described above also has the effect of flattening the surface of the i-wire in the region.

〔Effect of the invention〕

As described above, according to the present invention, the surface area occupied by the conventional fuse (the width W of the polysilicon fuse 24 was about 20 μm as seen in FIG. 3) due to its planar extension is reduced. The fuse element of the present invention has the advantage that it can be shortened to a width of about 5 μm, indicated by W' (first equivalent), and is effective for building up LSIs, and that the fuse element of the present invention can be formed by a normal semiconductor process.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a redundant circuit configuration, and FIG. 3 is a plan view of a conventional example. In FIG. 1, 11 is a silicon substrate, I2 is an n+ type layer, 13 is a 5i02 film, and 14 is A! ! 15 is an AN-5i alloy layer, 16 is a contact hole, and 17 is a laser pulse. Agent Patent Attorney Akira Kuki IM Agent Patent Attorney Yoshinoki Osuga

Claims (1)

[Claims] n^+ type layer (12) formed on p-type semiconductor substrate (11)
In order to insulate a fuse formed by forming an aluminum wiring (14) that conducts electrically via the A method of manufacturing a semiconductor device, characterized in that a p-type aluminum-silicon alloy layer (15) is formed at a junction part to bring an aluminum wiring (14) into an insulating state.