JPH05166941A - Semiconductor self-alignment contact structure and manufacture thereof - Google Patents

Abstract

PURPOSE:To contrive to have a titanium oxide layer, which works as an etching stop layer and works so as to isolate electrically a conductor region on the side surfaces of contact holes from plugs. CONSTITUTION:A semiconductor silicon substrate 1 has a first conductor layer 2 in its surface, the surfaces of the substrate 1 and the layer 2 are covered with a first insulator layer 3 and patterns consisting of a second conductor layer 4, which consist of a titanium or titanium capsule-filling conductive substrance, are formed on the surface of the layer 3. The upper surfaces and side surfaces of the patterns consisting of the layer 4 are encircled with a second insulator layer 5 consisting of a titanium oxide. The patterns are covered with a third insulator layer. Contact holes are respectively overlapped with the patterns consisting of the layer 4 at the ends of the respective patterns and an etching passes through the third and first insulator layers and is performed to the layer 2. The etching is not performed on the surfaces, which are covered with the layer 5, of the patterns. The contact holes 7 are filled with a third conductor layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor self-aligned contact structure and a manufacturing method.

[0002]

2. Description of the Related Art In a semiconductor device, a contact hole opened in an insulating layer separating two different first and second conductor layers is filled with a third conductor to form a contact hole plug. , Contact hole plugs electrically connect between the first and second conductor layers.

Current contact hole plugs and metallization devices use chemical vapor deposition (CV).
D) with polysilicon, tungsten, or titanium nitride plugs deposited. The plug fills the contact hole and makes electrical contact with the substrate through the bottom surface of the plug. In addition, it has a metallization layer covering the contact hole plug and makes electrical contact to the plug through the top surface of the plug.

[0004]

When the minimum dimensions of semiconductor devices are less than 0.5 μm, both the contact hole dimensions and the maximum tolerance for lithographic alignment between the various layers are extremely small. For example, 256 Mbit
In DRAM devices, the minimum contact hole size is about 0.25 μm, requiring alignment tolerances of 0.05 μm or less. Since such small contact hole dimensions and tolerances cannot be achieved by conventional photolithography, a self-aligned contact process is used. In this process, large contact holes are opened above the lower pattern, which acts as a mask during contact hole etching. This contact hole is said to be self-aligned because it is etched between the lower patterns. The etch stop layer protects the underlying pattern from being etched during contact hole etching and plays an important role in this process. Polysilicon is the most suitable material for this purpose.
However, the additional thickness of the polysilicon etch stop layer increases the pattern step height on the wafer, which makes surface planarization difficult. Furthermore, the surface of the polysilicon etch stop layer within the contact hole shorts to the contact hole plug. To prevent this, a thin SiO ₂ layer must be deposited on the sidewalls of the contact holes, which reduces the diameter of the contact holes and increases both the plug resistance and the contact resistance between the plug and the conductor layer.

An object of the present invention is to provide a semiconductor self-aligned contact structure and a manufacturing method which solve the above problems.

[0006]

A semiconductor self-aligned contact structure of the present invention is a semiconductor substrate and a first impurity-doped silicon layer formed on the surface of the semiconductor substrate.
A conductor layer, a first insulator layer covering the first conductor layer, and a second conductor layer of titanium or titanium-encapsulated conductive material formed on the first insulator layer. A pattern, a second insulator layer of titanium oxide formed on the upper and side surfaces of the pattern of the second conductor layer, a third insulator layer that covers the pattern of the second conductor layer, and the third insulator layer. A contact hole existing between the patterns of the second conductor layer and extending to the first conductor layer through the first and third insulator layers; and a third hole filling the contact hole.
And a conductor layer of.

Further, according to the method of manufacturing a semiconductor contact hole structure of the present invention, the single crystal silicon substrate is doped with impurities.
Forming a first conductor layer of silicon; depositing a first insulator layer on the substrate;
Depositing a second conductor layer of titanium or titanium encapsulating conductive material on the insulator layer and etching to form a pattern; and annealing the pattern in oxygen to form top and side surfaces of the pattern. Forming a second insulator layer of titanium oxide on the substrate, depositing a third insulator layer on the pattern, and forming contact holes overlapping the edges of the pattern with the second insulator layer.
And etching the first conductor layer to the first conductor layer while leaving the insulator layer as it is, and filling the contact hole with the third conductor layer.

Further, the titanium oxide coating the titanium or the titanium-capsule-filled conductive material contains 600 to 800 of the titanium or titanium-capsule-filled conductive material.
It is formed by annealing in oxygen at ℃.

[0009]

The titanium oxide layer on the top or side of the titanium pattern serves two purposes. The first purpose is as an etch stop layer to protect the lower conductor from being etched during the contact hole etching process. A second purpose is to act as an insulator layer to electrically isolate the conductor regions on the sides of the contact holes from the plugs that fill the contact holes and make electrical contacts to the substrate. Titanium oxide is an insulator and is suitable for polysilicon. This is because the polysilicon left unconnected to the conductor, as an ungrounded or "floating" surface, provides a capacitive coupling effect during device operation.

[0010]

Embodiments of the present invention will be described with reference to the drawings. 1 and 2 are views showing an embodiment of a semiconductor self-aligned contact structure of the present invention and a manufacturing method thereof. The structure will be clarified while explaining the manufacturing method.

First, as shown in FIG. 1A, a first conductor layer 2 doped by arsenic implantation is formed on a silicon substrate 1, and then a first insulator layer 3 made of SiO ₂ is formed.
To cover.

Next, as shown in FIG. 1B, a second conductor layer 4 made of titanium is sputtered on the SiO ₂ layer 3. Subsequently, a resist (not shown) is applied, a pattern is defined in the resist by a lithographic technique, and the titanium layer is etched by reactive ion etching.

Next, as shown in FIG. 1C, the pattern is annealed in oxygen in a rapid thermal processing chamber at 600 ° C. to form a second insulator of titanium oxide on the top and side surfaces of the titanium pattern. Form layer 5. Next, as shown in FIG. 2D, a third insulator layer 6 made of SiO ₂ is deposited on this pattern.

Next, as shown in FIG. 2E, a resist (not shown) is applied, and a contact hole pattern which overlaps the titanium pattern is defined by a lithographic technique, and a third hole between the titanium patterns is defined. The insulator layer 6 of the
The insulating layer 3 is etched to the first conductor layer 2 to open the contact hole 7. This etching is titanium
Stop at the second insulator layer 5 covering the pattern.

Finally, as shown in FIG. 2 (f), the contact hole 7 is filled with a third conductor layer 8 of phosphorus-doped polysilicon.

As described above, according to this embodiment, the contact hole defined in the resist with a size larger than the minimum size, which is covered with the titanium oxide / etching stop layer, is used as a mask, Contact holes are etched between the patterns to provide "self-aligned" contacts to the titanium oxide insulator, which insulates the lower conductor pattern electrically from the contact hole plugs. Is formed.

[0017]

The self-aligned contact structure and fabrication method of the present invention are compatible with current wafer fabrication processes. This is because titanium is commonly used as a barrier layer under aluminum. The rapid oxidation of titanium can form a thin insulator on the surface of the conductor pattern that acts as an etch stop layer during contact hole etching and as an insulator that separates the conductor pattern from the contact hole plug. it can.

[Brief description of drawings]

FIG. 1 is a diagram showing a method of manufacturing a semiconductor self-aligned contact structure, in which (a) shows a step of forming a diffusion layer and a first insulator layer, and (b) shows a conductive pattern on a titanium layer. (C) shows the step of forming a titanium oxide layer on the surface of the titanium pattern.

FIG. 2 is a diagram showing a method of manufacturing a semiconductor self-aligned contact structure, in which (d) shows a step of depositing a second insulator layer on a titanium pattern coated with titanium oxide,
(E) shows a step of etching a contact hole passing through the second and first insulator layers between titanium patterns, and (f) shows a step of filling the contact hole with phosphorus-doped polysilicon. .

[Description of Reference Signs] 1 semiconductor substrate 2 first conductor layer 3 first insulator layer 4 second conductor layer 5 second insulator layer 6 third insulator layer 7 contact hole 8 third conductor layer

Claims (3)

[Claims] 1. A semiconductor substrate, a first conductor layer of impurity-doped silicon formed on the surface of the semiconductor substrate, a first insulator layer covering the first conductor layer, and the first conductor layer. A pattern of a second conductor layer of titanium or a titanium-encapsulated conductive material formed on the insulator layer, and a second layer of titanium oxide formed on the top and side surfaces of the pattern of the second conductor layer. An insulator layer, a third insulator layer that covers the pattern of the second conductor layer, and a pattern that exists between the second conductor layer and passes through the first and third insulator layers. A semiconductor self-aligned contact structure having a contact hole extending to the first conductor layer and a third conductor layer filling the contact hole. 2. A step of forming a first conductor layer of impurity-doped silicon in a single crystal silicon substrate, a step of depositing a first insulator layer on the substrate, and a step of depositing the first insulator layer. Depositing a second conductor layer of titanium or titanium encapsulating conductive material thereon and etching to form a pattern; and annealing the pattern in oxygen to form titanium oxide on the top and side surfaces of the pattern. Forming a second insulator layer, depositing a third insulator layer on the pattern, and leaving contact holes overlapping the edges of the pattern in the second insulator layer. Etching the first conductor layer into the first and third insulator layers, and filling the contact hole with the third conductor layer. Conductor self-aligned contact manufacturing method. 3. The titanium oxide coating the titanium or titanium encapsulating conductive material is formed by annealing the titanium or titanium encapsulating conductive material in oxygen at 600 to 800 ° C. A method of manufacturing a semiconductor self-aligned contact as described.