JPH022147A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve an electromigration strength by a method wherein the mask pattern of a hole part is formed by giving a limited width to a curve similar to a Hilbert curve of any digit. CONSTITUTION:When a current is made to flow along the direction A-A' in an upper metal layer 11, the most of a part of the current flowing downward through a hole part 12 flows through an (a0+a2) part and then through an (a1) part and two (b0) parts and the remaining current flows through two sides (b). As a longer circumferential length is provided than in the case of receiving the current with one side (a) only by 2X(b0), the current applied to a unit length of the circumference is smaller than in the case of providing no bent parts, so that an electromigration strength can be improved.

Description

[Detailed Description of the Invention] [Summary of the Invention] A method for manufacturing a semiconductor device, particularly electromigration (e) of wiring in a hole (opening) of a semiconductor device.
Regarding a hole design method for improving electromigration resistance, the present invention aims to provide a method that solves the problem of insufficient electromigration resistance with conventional hole mask patterns by changing the shape of the hole mask pattern. For the purpose of forming a mask pattern for a hole in a semiconductor device, Hilbel of any order! -(I
(libert) give a finite width to a graph similar to the curve,
Alternatively, a method for manufacturing a semiconductor device is characterized in that the Hilbert curve at an arbitrary position is geometrically deformed so that the amount of current flowing from the peripheral part per unit length of the ball part is smaller than that in the case of a hole part without bending. Contains and composes.

[Industrial application field]

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for designing a hole (opening) of a semiconductor device to improve electromigration resistance of wiring in the hole (opening).

[Prior Art] With the recent miniaturization of semiconductor devices, electromigration of wiring in hole portions has become a problem.

Electromigration is, for example, when a wiring is made of aluminum (Al), when a current is passed through which wiring, eight atoms move, and the number of Al atoms decreases in some parts of the wiring. This is the phenomenon where the wiring breaks.

In conventional semiconductor devices, mask data for hole portions are made of rectangles, circles, and sets of these. Third
Figures (a) and (b) are a plan view and a cross-sectional view showing an example of the wiring of the pole part, where 1 is a semiconductor substrate, 2 is an insulating film,
3 is the pole part formed in the insulating film, and 4 is the upper layer wiring! In this example, the upper layer wiring 4 is in contact with the impurity diffusion layer formed on the substrate l!・I am taking . The shape of the hole part is formed into a rectangle using a mask pattern, but the mask pattern is not limited to a rectangle.
There are circular shapes and combinations of rectangular and circular shapes.

[Problem to be solved by the invention]

Due to the reduction in step coverage of wiring in hole portions due to the recent miniaturization of semiconductor devices, electromigration has started to occur not only in the original wiring portion but also in wiring in hole portions.

Conventionally, wiring portions (line portions) and hole portions have been designed to meet current density standards. By the way, there are many unknowns about the movement of current in the hole section, and when a large current is passed through a bipolar transistor, there are cases where disconnection occurs not only in the line section but also in the hole section. In the hall part, Fig. 3(b)
As shown by the arrow in , the current flows down like a waterfall in the hole section, but in the hole section ^! Disconnection occurs when the thickness of the wiring 4 becomes thinner, and as miniaturization and higher density progress, the wiring becomes sensitive to electromigration in parallel between the line portion and the hole portion. By the way, in the line part it is easy to calculate how to design it, but in the hole part, the direction of current flow and how much current flows in which direction have not yet been fully clarified. It is difficult to evaluate the electromigration resistance of the hole part.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method that solves the problem in which sufficient electromigration resistance cannot be obtained with the conventional hole mask pattern by changing the shape of the hole mask pattern.

(Means for Solving the Problem) The above problem is to solve the problem in forming a mask pattern of a hole portion of a semiconductor device.
rL) By giving a finite width to a graph similar to the curve, or by geometrically deforming the Hilbert curve at an arbitrary position, we can calculate the amount of current flowing from the periphery per unit length of the hole compared to the case of a hole with no bend. This problem is solved by a method of manufacturing a semiconductor device, which is characterized by reducing the amount of damage.

[Effect]

2(a) and (b) are diagrams explaining the principle of the present invention. In the figures, 11 is the upper layer metal, 12 is the hole portion (the lower layer metal is not shown), a is one side of the hole, and b is the One side of the hole perpendicular to a, a, +b, +a, +b0+a, indicates one side of the bent hole facing a. Electric current flows from 11 to 12 to the lower metal layer (including the semiconductor substrate), and in FIG. 3(b), the amount of current flowing through each part is expressed by the thickness of the arrow and marked with a symbol.

In the present invention, when a current flows through the upper metal layer 11 in the direction A→A' as shown in FIG. A significant portion of (“2xao”) flows in, and then “
A1" flows into each of the two parts.
The remaining two sides flow in by "b". In this case, the peripheral part of the hole increases by 2xbo compared to the case where it is received by - side a (corresponding to ao + at + at), so the flow from the peripheral part per unit length increases. The amount of current that flows is smaller than in the case without bending, and the electromigration resistance is improved.

In addition, even if a disconnection occurs in the weakest (the most severe conditions) ao and a2 parts, the two 50 parts exist, so the path for the current to flow is still secured, and the peripheral length simply increases. Beyond this primary effect, the time it takes for the product to become defective is extended. If a break occurs when the wire is supported on the A-side as in the past, it has no choice but to flow from the remaining two sides, and the present invention makes it difficult for the phenomenon that manifests as a contact failure before the wire breaks completely to occur. .

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to illustrated embodiments.

FIG. 1(a) is a block diagram of one embodiment of the present invention, showing a hole portion of a semiconductor device. In the figure, the same parts as shown in FIG. 2 are indicated by the same symbols. is the upper layer metal,
12 is a hole part, a is one side of the hole, b is one side of the hole perpendicular to a, ao+bo+a+ten, +a is one side of the bent hole opposite to a.

FIG. 1(b) shows the mask data for the hole 12 in FIG. 1(a) (shown with diagonal lines in FIG. 1(a)), which is expressed as an equivalent pattern by line segments, ignoring the width. Since the data becomes complicated, the following embodiments will be expressed in this manner unless otherwise specified.

A second embodiment is shown in FIG. 1(C). In this example,
It is highly effective if the main current path is arranged as A-+A'.

A third embodiment is shown in FIG. 1(d). In this case too, A→A
The effect is great if the current flows in the ′ direction.

A fourth embodiment is shown in FIG. 1(e). In this example as well, it is better to let the current flow in the direction of A-+A'.

A fifth embodiment is shown in FIG. 1(f). This is shown in the same figure (e
), the two large blocks on the left half of the example are rotated to make the whole into a closed loop.
When viewed as a modification of the example shown in (1) in the same figure, it becomes a pattern that is strong against currents in both directions, A#A'.

Here, the example in Figure 1(b) is of order 1, the example in Figure 1(C) is of order 2, the example in Figure 1(d) is of order 3, and the example in Figure 1(e) is of order 1. The example is a 1libert curve of order 4, and the example in figure (f) is a modification of the example in figure (e), and the actual mask pattern is! It can be regarded as a filbert curve with a finite width, and the old 1ber curve of any order
The present invention is implemented by giving a graph similar to the t-curve (and its geometric variations) a finite width. t
The reason why the Lilbert curve is adopted is that it is proven by a mathematical theorem that this curve can be embedded most densely in a plane, and it becomes the longest pattern in total extension within a given area, and the current This is because the inflow route of is the maximum.

Figures 1 (a) to (f) are configuration diagrams of embodiments of the present invention, and Figure 2 (
(a) and (b) are explanatory diagrams of the principle of the present invention, and FIG. 3 is a diagram of the hole portion, of which (a) is a plan view and (b) is a cross-sectional view.

In the figure, 11 is the upper layer metal, 12 is the hole part, as aos al, d2, b is the hole edge part, A,
A' indicates the direction in which the current flows.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to systematically determine the shape of a hole portion that is resistant to electromigration and to obtain an optimal arrangement, which greatly contributes to miniaturization and improved reliability of semiconductor devices.

Claims (1)

[Claims] In forming a mask pattern for a hole portion (12) of a semiconductor device, a graph similar to a Hilbert curve of an arbitrary order is given a finite width, or a Hilbert curve at an arbitrary position is given a geometric shape. A method for manufacturing a semiconductor device, characterized in that the amount of current flowing from the peripheral portion (b, b_0) per unit length of the hole portion (12) is made smaller than that in the case of a hole portion without bending by performing a chemical transformation.