KR940007056B1 - Forming method of interlayer insulating film - Google Patents

Abstract

The method includes the steps of forming an oxide layer on a silicon wafer, depositing a first aluminum on the oxide layer by sputtering, depositing an oxidised nitride having compressive stress on first aluminum by plasma chemical vapor deposition method, forming a predetermined photoresist pattern on the oxidized nitride, forming a via hole in a predetermined portion and carrying out planarizing process, forming a second aluminum layer on the resultant.

Description

Method of forming double metal layer insulating film of semiconductor

Figure is a process chart for practicing the present invention.

The present invention relates to a method of forming an insulating film of a double metal layer (DOUBLE METAL LAYER) during the semiconductor manufacturing process.

In the conventional double metal layer insulating film forming method, the formation of the insulating film and the planarization of the insulating film are very complicated and the unit process cost is high. In addition, when the line width between the aluminum wirings is very small and the surface step is severe, there is a problem in that the yield and reliability of the beads are decisively reduced.

This conventional double metal layer operation diagram is shown in the following Table-1.

TABLE 1

Table 1 Existing Double Metal Layer Work Diagram

* Note: [Method 1], [Method 2] and [Method 3] of <Table-1> are separate flattening methods.

In the case of the phosphorylated film of the conventional double metal layer insulating film, when the line width between the first aluminum wirings is very small, the gap between the aluminum wirings is not sufficiently filled, and a cavity (small filled space) is generated. ) Is not sufficiently suppressed, causing a short circuit between the aluminum layers. In addition, since the use temperature is limited, it is impossible to achieve sufficient planarization.

Inadequate planarization due to such hillock growth and cavitation can increase the leakage current of the device, reduce reliability and yield, and shorten the lifetime.

In addition, in the case of the nitride film of the conventional insulating film, it is difficult to control the stress of the film itself, and the stress of the film itself is high, so that a crack is likely to occur due to thermal stress generated during the process. In addition, high film stresses significantly degrade functionality during device operation. In addition, the nitride film itself has a poor buried flatness, so it cannot be used alone as a double metal layer insulating film, and has to be used together with other materials. In fact, spin-on-grass (SOG) and polyamidazole quinazoline (PIQ) are very good in flatness, but as shown in <Table-1>, they cannot be used for flattening alone, and in-process baking and curing It takes a long time. In addition, spin-on-glass has a lot of cracks during baking and aging, and productivity is greatly reduced due to the complexity of the process.

Polyimidazole quinazoline is also limited in device size due to the large thermal expansion coefficient difference between silicon and aluminum, and when these materials are used arbitrarily as a double-metal layer insulating film, short holes and leakage currents between metal wirings are affected by the effects of pinholes and cracks. Cause. The conventional planarization method for forming an insulating film is very complicated and takes a long time due to the characteristics of the insulating film. The problem is the reliability.

In order to solve these problems, the present invention uses an appropriate insulating film and simultaneously performs planarization and via hole etching, thereby improving productivity by simplifying the process and shortening the process time, realizing perfect filling planarization technology, and using an appropriate insulating layer. To improve the reliability.

That is, the present invention uses an oxynitride film as the insulating film in order to satisfy the condition that the insulation flatness of the insulating film should be excellent, the stress control of the film itself should be easy, and the process should be simple and the film properties should not affect the device characteristics. The selective etching of the oxynitride film and the photoresist allows simultaneous planarization and via hole forming operations, and the buried flatness is excellent so that a separate planarization process is not necessary. In particular, the oxynitride film has an aluminum line width and spacing. In the case of very narrow and large surface level difference and curvature, the buried flatness is excellent and the stress of the film can be adjusted to an appropriate level, so it is not sensitive to thermal stress generated during device manufacturing or operation, thereby improving the reliability of the device. With reference to the accompanying drawings of the present invention If you explain in detail as follows.

The insulating film between the first aluminum wiring and the second aluminum wiring is deposited by an oxynitride film (OXYNITRIDE, SixNyOz: x, y, z are non-stoichiometric coefficients) using a plasma vapor deposition method.

A photoresist is applied on the deposited oxynitride film by a rotational coating method, and a via hole (VIAHOLE: a through hole connecting the first aluminum wiring and the second aluminum wiring) is masked on the wafer. After masking the via holes, dry etching is performed using a dry etching method with a selective etching ratio of the photoresist and the oxynitride film as 0.9: 1. During the via hole etching, the planarization of the insulating film and the via hole formation proceed simultaneously.

In particular, this technique is very effective when the gap between the first aluminum wirings is very small and the surface level of the first aluminum wiring is large, making it difficult to planarize the buried surface. It greatly improves device reliability by greatly improving flatness, simplification of process, and significant improvement in film stress.

When explaining the present invention in more detail according to the embodiment as follows.

EXAMPLE

As shown in the drawing, an oxide film (Fig. 2) is formed on a silicon wafer (Si WAFER) (Fig. 1) and then the first aluminum (Fig. 3) is sputtered. By vapor deposition.

In this manner, after completing the pattern shown in Fig. [B], an oxynitride film (Fig. [4] -4) is deposited by plasma vapor deposition. The furnace temperature during deposition is deposited at a low temperature of 320 degrees Celsius in order to suppress aluminum hillock growth to the maximum, and the gases used at this time are silane (SiH ₄ ), nitrous oxide (N ₂ O), and ammonia (NH ₃ ).

In order to minimize the effect of the stress of the insulating film on the characteristics of the device and to eliminate the breakdown of the insulating film due to thermal stress, the insulating film has the characteristics of compressive stress and the magnitude of the stress is 1.5 to 1.9 x 10 ⁹ DYNE. Make it / CM ² Periodic measurement of stress is instead measured with the refractive index (REFRACTIVE INDEX). At this time, the refractive index is 1.78 +/- 0.02, and the compressive stress of the oxynitride film can minimize the effects of moderate suppression of hillock and the difference in stress and thermal expansion coefficient of aluminum and silicon. In addition, the thickness of the oxynitride film (Fig. 4) is deposited at 2.4 +/- 0.2 μm, and the planarization is almost flattened after the deposition as shown in Fig. C using the maximum isotropic deposition characteristic of the film itself. You have a surface. Subsequently, the photoresist (Fig. 5) is applied after the oxynitride film is deposited. The thickness of the photoresist is applied to a thickness of 1.5 μm to maximize the degree of flatness.

After the photoresist (Fig. 5) is applied, the via hole masking operation (Fig. 5) is performed, and after the via hole masking operation, the through hole is penetrated and planarized by dry etching. Simultaneously perform the figure [bar].

After the planarization, the thickness of the oxynitride film (Fig. 4) becomes 1.2 to 1.4 μm, and after the planarization and the via hole penetrating operation are performed as shown in Fig. 2, the second aluminum layer is shown as Fig. 4 After the deposition of the second aluminum wiring work, the final smoothness will be as shown in (Fig. 4).

In this manner, the present invention is a useful invention that enables to improve the productivity and the reliability of the device to be manufactured by simplifying the process and shortening the process time.

Claims (1)

After the oxide film is formed on the silicon wafer, the first aluminum is deposited by sputtering, and the oxynitride film is deposited thereon by plasma vapor deposition. The compressive stress has a characteristic of l.5-1.9 ×. 10 ⁹ DYNE / CM ² and the photoresist is applied, via hole masking is performed, and through hole etching and through flattening are simultaneously performed using a dry etching method, and a second aluminum layer is deposited thereon. A method of forming a double metal layer insulating film of a semiconductor.