JPH02133923A - Manufacture of semiconductor device - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Field of Application) The present invention relates to a method of manufacturing a semiconductor device, and particularly relates to a method of manufacturing a semiconductor device, and in particular a wiring pattern formed on a contact hole or a through hole with steep sides. The present invention relates to a flattening method.

(Prior art) In wiring technology in the manufacture of semiconductor integrated circuits, for example, multilayer wiring technology for semiconductor elements, contact holes or through holes are filled with wiring metal such as aluminum (Aff), and uneven stepped portions, etc. There is a bias scattering method as a planarization technique. For example, IEE
E PROCEEDINGS OF THEINTER
NATIONAL ELEC:TR0N DEVI
CES MEETING DEC7-101986
There is a method disclosed in P70-73. That is, as shown in Fig. 2, in order to prevent the deterioration of the film quality due to the release of impurity gas such as oxygen that adhered to the surface of the substrate before introducing the substrate into the vacuum chamber, and the damage caused by WI impact at the bottom of the contact hole, A semiconductor substrate as shown in (A), for example, Si
Silicon oxide (SiO,) (12) on substrate (11)
As a first step, a base film (14) of aluminum or aluminum alloy or high melting point metal and its silicide is applied to the opening (13) of the Si substrate (11) using a normal sputtering method as shown in FIG. ), and in the second step, as shown in Figure 2 (C), aluminum or aluminum alloy is deposited as a film on the Si substrate (11) in a heated state by bias sputtering, and the heating effect due to bias and ion bombardment are Due to P such as surface tension at a temperature lower than the melting point of An or Aj2 alloy, A is formed in the contact hole.
2 or A2 alloy is flowed and embedded.

In addition to the above, there is also a method of embedding the opening, F126.
SEMICONDUCTOR INTERNATION
AL 9/1987j and fi' SEMICON J
APAN '86 TECHNICAL SYMPO5
IUMTOKYO, JAPAN, Decll-1219
86 “PLANARIZATION 0 FAL AL
LOY METALIZATION BY 5I
IRFACE 5ELF-DIFF-USION"j
There are also technologies disclosed in

(Problem M to be solved by the invention) However, the above conventional method has the following problems. First, in the former two-step process, when aluminum or aluminum alloy is used for the first layer (first step), if the film is thin, it will form an island (
16) (Figure 3 (A)) In particular, in miniaturized elements where the contact hole recess is small, if the metal film thickness in the first step is made too thick, the upper end of the recess (41) As shown in Figure 4 (A), the bridge (
42), and on top of this, an aluminum layer (step 5) is formed in the second step.
) is bias sputtered, a contact hole (13
) There was a problem in that a cavity (43) as shown in FIG. 4 (B) was likely to occur. Another phenomenon in Figure 4 (B) is Figure 5 (E
), (F), the contact hole (13
) may not adhere to the side walls, or may adhere only to one wall surface. In addition, in the former two-step process, if a high-melting point metal is used in the first step, defects such as pinholes will occur if the film is thin, and oxygen, which is generated during bias sputtering from the base layer, etc. It was impossible to prevent the gas. In addition, as a means to improve the wettability of the latter contact hole, T
This method involves bias sputtering an aluminum layer after depositing a thin layer of iV, but when forming an aluminum layer on TiWl15, the film quality deteriorates due to the generation of impurity gas from the base through the TiV crotch, resulting in the problem shown in Figure 3 above. (A)
There were problems in that the aluminum layer was deposited in island-like form, the grain size became large and lacked flatness, and voids were generated at the grain boundaries. Further, when Q-5i alloy is used for the aluminum layer, silicon nodules are generated, making it difficult to etch when forming a pattern in a subsequent step. In addition, as a method of embedding the opening, a method using the resputtering effect is described in J. ELECTROCH.
EM、SOC、5OLIDSTATE 5CIEN
CE AND TECHNOLOGY JUNE
1985 P1466-1472. However, this method has a problem in that it takes a long time because the film is formed to a thickness that does not close the opening, and the film is filled in by deposition by sputtering and etching by bias sputtering.

The present invention has been made in response to the above-mentioned prior art situation, and provides a method for manufacturing a semiconductor device that has a wide range of process conditions, can obtain good coverage, and can fill recesses with high-quality metal. This is what I am trying to do.

[Structure of the invention]

(Means for Solving Iillg) The present invention provides a semiconductor device manufacturing method 1 in which a metal is buried in a recessed portion of a substrate surface, in which a reaction between a Si substrate and an ^a or i alloy is applied to the surface including the recessed portion. A first step of depositing a first metal with a high melting point as a so-called diffusion barrier metal that has the effect of preventing diffusion, and depositing titanium (Ti) on the first film to a thickness such that the recesses are not closed. The method is characterized by comprising a second step and a third step of bias-sputtering the third metal and a third metal having a lower diameter than titanium into the recessed portion.

(Working bed) In a method for manufacturing a semiconductor device in which metal is embedded in a recess on a substrate surface, a first step of depositing a first metal with a high melting point on the surface including the recess, and a step on the first film described above. a second step of depositing titanium (Ti) to a thickness that does not close the recess, and a third step of bias sputtering the first metal and a third metal having a lower melting point than titanium on the four parts. Titanium (T
The gettering effect of i) prevents the generation of impurities from the first metal, prevents the segregation of silicon (Si) that occurs when forming the third metal, and reduces the particle size. It is possible to form 7 ml of gold with a smooth shape in the uneven part and a flat surface.

(Embodiment 9 An embodiment of the method for manufacturing a semiconductor device of the present invention will be described below with reference to the drawings.

Semiconductor substrate, for example, a silicon (Si) semiconductor wafer 0
An insulating layer (2) such as a silicon dioxide film formed on the surface is provided with a recess, for example, an opening exposing the surface of the semiconductor wafer 0, and this opening is called a contact hole (2). Into this hole (2), without preheating the semiconductor wafer (2), a first metal (for example, a titanium nitride (TiN) film, which is a nitride of high melting point metal titanium) is deposited as shown in FIG. 1(A). Thickness, for example several 100 to 300
The first layer, that is, the barrier metal, which is a diffusion barrier layer between metals, is deposited on approximately 0 people by the usual sputtering process (first step). In this case, the temperature of the wafer may increase due to sputtering. . At this time, a thin first layer (barrier metal) is also formed on the surface of the silicon dioxide film (2). At this time, the semiconductor wafer ■ is preheated, e.g.
It may be set to 00°C.

Next, as a second step, as shown in Figure 1 (B), the prevention of impurities generated from the above-mentioned layer barrier metal and the segregation of silicon that occurs during aluminum film formation by bias sputtering method in the third step. In order to prevent voids that may occur in the step portions, a titanium (Ti) layer 0 having a gettering effect is coated to a thickness of several tens to several hundreds of layers so that the contact hole (3) is not closed.
For example, it is deposited by a commonly used sputtering method. Next, as a third step, as shown in FIG. Here, in this step, in order to improve step coverage even if the aspect ratio is large, for example, the semiconductor substrate
RF bias, for example, a self-bias voltage of 300 Volt, is applied to the semiconductor substrate (2) in a heated state of about 10°C, and
After raising the temperature from 0° C. to 400° C., sputtering is performed while increasing the temperature to deposit an aluminum layer (1).

That is, according to such a bias sputtering method, the ^Q film is first deposited at a low temperature, so that it covers the entire surface of the semiconductor substrate without forming an island-like growth on the side surface of the contact hole, which is a fine opening. , the temperature rises to the set temperature in about 60 seconds using the substrate heating mechanism alone), and the heating effect due to RF bias and A due to argon ions.
In order to promote defects and distortions in the Q crystal and to make it easier to flow or deform below the melting point of 80, the aluminum can move smoothly into the contact hole (3) and fill the contact hole (■). .

The above first, second, and third steps are performed continuously without being exposed to the atmosphere, and as a means to obtain the same effect, the substrate is exposed to the atmosphere between the first and second steps. There is a way to execute it discontinuously.

Further, the first, second, and third steps may be performed in a film forming apparatus consisting of a single chamber or a so-called multi-chamber in which each processing chamber is independent, without being exposed to the atmosphere.

As in the above embodiment, when forming a wiring pattern in a recess such as a contact hole formed on the substrate ω, a titanium WJ is deposited on the barrier metal layer (a) as the -th layer, and this titanium layer is ■If an aluminum layer 0 is deposited on top by bias sputtering, an aluminum layer, for example, is formed as shown in Figure 6, and it is different from the conventional aluminum layer deposited by bias sputtering, which does not include a titanium layer, as shown in Figure 8. In comparison, the effect of titanium can reduce the grain size of aluminum alloys, eliminate defects such as abnormal silicon precipitation and voids that occur at grain boundaries, and create a smooth surface.

Further, in this example, complete flattening was possible with a diameter of 1.0 microns and an aspect ratio of 1. Furthermore, it can be seen that the film quality is further improved compared to the conventional aluminum layer deposited by sputtering without applying a bias, which does not include a conventional titanium layer, as shown in FIG.

This invention is not limited to the above embodiment, but the gold 5! deposited in the first step! The film may be any metal film with a high melting point, such as W, TiV, or silicide-based MoS.
ix, WSi, TiSi, TaSi, etc., and the metal deposited by bias sputtering in the third step may also be an aluminum alloy of two or more elements, and the same effect as in the above embodiment can be obtained.

[Brief explanation of drawings]

Figure 1 is for explaining an embodiment of the method of the present invention.
Figure 2 is a diagram to explain the secondary method; Figures 3, 4, and 5 are diagrams explaining problems caused by the method in Figure 2; Figure 6 is the surface of the aluminum film formed by the method in Figure 1. Figures 7 and 8 are diagrams representing the crystal structure of the surface of an aluminum film formed by the conventional method. 1...Silicon substrate 2...Oxide film 3...Contact hole 4...First metal film (pariamekuru) 5...Titanium film 6...Aluminum film Patent applicant Tokyo Electron Ltd. Figure 1 Figure 3 (A) (B) Figure 2 Property 4 (田 (A) (8 ん (C) (A) Figure (A) (E) Queen t 1? I crawl γ back 1 figure

Claims (5)

[Claims] (1) A method for manufacturing a semiconductor device in which a metal is embedded in a recess on a substrate surface, including a first step of depositing a first metal, which is a high-melting point metal, on the surface including the recess, and a titanium film on the first film. a second step of depositing (Ti) to a thickness that does not close the recess; and a third step of bias sputtering a third metal having a lower melting point than titanium into the recess. A method for manufacturing a featured semiconductor device. (2) The method of manufacturing a semiconductor device according to claim 1, wherein the first metal is a diffusion barrier metal made of titanium nitride or high melting point silicide. (3) The method for manufacturing a semiconductor device according to claim 1, wherein the third metal is the same type of aluminum or aluminum alloy. (4) A claim characterized in that the first, second, and third metals are processed in a film forming apparatus consisting of a single chamber or a so-called multi-chamber in which each processing chamber is independent, without being exposed to the atmosphere between each process. 1. The method for manufacturing a semiconductor device according to 1. (5) The method of manufacturing a semiconductor device according to claim 1, wherein the process is performed by exposing the first metal to the atmosphere between the steps of forming the first metal and the second and third metals.