JPH0425159A - Forming method of electrode wiring - Google Patents

Abstract

PURPOSE:To enable a tungsten selective growth technique to be applied to a connection hole provided to a board by a method wherein a metal thin film is left inside the hole taking advantage of a resist etch-back method, and tungsten is made to grow there. CONSTITUTION:An insulating film 2 is deposited on an Si board 6, and a connection hole 3 is provided to the insulating film 2. Then, a thin film 8 of metal, metal silicide, or semiconductor is formed, and a resist 9 is applied onto all the surface, which is etched to leave the thin film 8 only inside the hole 3. Then, a tungsten 4 is selectively grown inside the hole 3, and a wiring metal 5 is formed thereon. By this setup, tungsten is selectively grown without any problem in a contact hole through which an element and a wiring metal are connected and can be shortened in growth time.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to wiring technology used in the manufacture of various solid-state devices such as semiconductor integrated circuits. Specifically, the present invention relates to wiring technology used in manufacturing various solid-state devices such as semiconductor integrated circuits. This article relates to a selective growth method for tungsten that produces a structure with a unique structure.

[Conventional technology]

Multilayer wiring technology is essential to realizing high-density integrated circuits. In order to realize this multilayer wiring structure, it is necessary to connect MOS, bipolar, etc. elements and metal wiring with an insulating film in between, or between metal wiring layers such as 1st-layer wiring and 2nd-layer wiring. It won't happen. Conventionally, for this connection, a desired hole is opened in the insulating film, and a metal wiring is inserted into the hole at the same time as the upper layer of metal wiring is formed.
Connectors were connected between wires and wires, and wires were connected between wires. However, in recent years, the diameter of holes for connections has become on the order of submicrons, and the hole depth/hole diameter (aspect ratio) has become more than 1.0, so metal wiring does not fit into the holes. , I was having trouble connecting. To solve this problem, a selective growth method for tungsten has recently been proposed. In this method, tungsten is selectively formed only in the holes for connection, and since the metal wiring is connected to the element or the underlying metal wiring through the tungsten, there is no need to enter the hole. This tungsten selective growth method uses tungsten hexafluoride (
WF6) is reacted with hydrogen under reduced pressure and heat, and the reaction of reducing WF6 with hydrogen and producing tungsten metal does not occur on insulating layers such as oxide films.
This method takes advantage of the fact that tungsten occurs on metals or semiconductors, and grows tungsten only within the connection holes. Until now, this method has been mainly used for connections between metal wirings and metal wirings. FIG. 1 shows an outline of this method. First, as shown in FIG. 1A, a connection hole (pier hole) 3 is formed in an insulating film 2 formed on a wiring metal 1. Next, as shown in FIG. 1B, tungsten is selectively grown to form tungsten 4 in the connection hole 3. Then, as shown in FIG. Finally, as shown in FIG. 1C, an upper layer wiring metal 5 is formed to obtain a multilayer wiring structure. J: Uni, tungsten selective growth technology is now indispensable for multilayer wiring structures. However, the disadvantages are that (1) it cannot be applied to connections between elements and wiring metals, and (2) the growth rate is slow and productivity is poor. Regarding the drawback (1) above, in detail, MO8LSI
When the above-mentioned selective tungsten growth technique is applied to the contact hole (contact hole) on the diffusion layer, as shown in FIG. 7, making it impossible to form a good connection. In order to solve this problem, a method of using silane (Sit-14) instead of or together with hydrogen has been proposed. However, even with this method, the formation of encolochement cannot be prevented, and the In addition, a new problem has arisen in that the growth rate is different on the P-type and N-type diffusion layers of complementary MO3LSI, and the thickness of the embedded tungsten is different.Furthermore, the selective growth method using silane reduction mentioned above , the grown tungsten is mixed with 3i from silane,
It also had the disadvantage of easily becoming -W and resulting in high resistance. In addition, regarding the problem of slow growth rate (2) above, it can be solved by not only avoiding the growth direction of tungsten from the top upwards, but also growing tungsten laterally from the side of the hole. As a method of selectively growing tungsten, a method has been proposed in which a metal film of Oga is sputtered and deposited on the side surfaces of the hole as well (Japanese Unexamined Patent Publication No. 1-65852). However, in this method, the sputtered metal is only deposited on the lower part of the side surface of the hole, so the aspect ratio is 1 to 1.0.
The above-mentioned holes cannot be used, and there are problems such as difficulty in controlling the amount of tungsten deposited, and it is difficult to grow tungsten stably from the lateral direction. [Problems to be Solved] In order to achieve a multilayer wiring structure, it is necessary to selectively grow tungsten in minute connection holes. However, in the connection between elements and wiring metals, it is difficult to There was a problem of variations, and also a problem of slow growth rate for connections between wiring metals.To solve this problem, silane reduction methods and lateral growth methods using sputtering have been proposed. However, the problem has not been solved satisfactorily.Therefore, an object of the present invention is to enable selective growth of tungsten even in contact holes between elements and wiring metals without any problem. ~ Both Hall and Pier Hall,
An object of the present invention is to provide a tangent selective growth technique that requires short growth time and high productivity. Specifically, after checking the connection hole, remove the metal or its silicide (
In this method, a thin film of silicide (silicide) or semiconductor is formed, the metal, silicide, or semiconductor is left only inside the hole (bottom and side surfaces) using a resist edge back technique, and then tungsten is selectively grown.1 [Problem] Means for Solving the Problem] The outline of the present invention will be explained using FIG. 3. First, as shown in FIG. 3A, an insulating film 2 is deposited on a 3i substrate 6 on which an element is formed, and the insulating film 2 is coated with
A connection hole 3 is formed using a known phosphorography method. Next, as shown in FIG. 3B, a thin film 8 of metal, silicide thereof, or semiconductor is formed by sputtering. In this case, the thickness of the thin film 8 may be arbitrary, and is usually 0.05
There is about ~0.2 μm of melon. Further, the thin film 8 can be formed not only on the bottom of the hole but also on the side surface. -To give an example, 0°8μm diameter, 0.5μm
If the thin film 8 is formed in a hole with a depth of m to 0.1 μm on the flat part, it will be 0.05 μm on the sides and 0.075 μm on the bottom.
A thin film 8 can be formed in the PJ-hole of m. Next, as shown in FIG. 3C, Regimes 1 to 9 are applied to the entire surface. In this case, Regime 1 may be the commercially available Photoresis 1, or may be a novolak resin or polyimide that does not contain a photosensitive group, but is not limited in any way. In short, any polymer (solution) that can flatten the holes by coating can be used. Next, as shown in FIG. 3, the entire surface of the resist 1 is etched (commonly called etch-back) by etching using gas plasma so that the resists 1 to 9 remain only inside the holes. In this case, a plasma containing oxygen as a species is used as the gas plasma. Next, as shown in FIG. 3F, the thin film 8 is etched and the resist 9 is removed, leaving the thin film 8 only inside the hole. Next, as shown in FIG. 3F, tungsten 4 is selectively grown. Finally, as shown in FIG. 3G, the wiring metal 4 is formed in step 3. According to the present invention, since the substrate such as the diffusion layer is protected by a metal thin film, There is nothing to generate. Therefore, the present invention can be applied to all connection holes, regardless of whether they are holes or via balls. Further, according to the present invention, as shown in FIG. 3E, the metal thin film can be left not only on the bottom of the hole but also on the side surfaces, so that tungsten can be grown from the bottom and side surfaces. As a result, it becomes possible to shorten the growth time and improve productivity. - As an example, when tungsten is selectively grown in a hole with a diameter of 0.8 μm and a depth of 0.5 μm, if there is no metal thin film inside the hole, the deposit amount of 1 However, when there is a metal thin film according to the present invention, the amount equivalent to 0.3 μm (7,5 μm) is required.
Amounts of 1 to 10 minutes (min/wafer) are sufficient. Furthermore, the growth action from the side produces a feature that allows the same amount to be deposited at the same time even in holes of different depths if they have the same diameter, so it is effective for one layer. Hereinafter, the present invention will be explained in detail using examples. [Example 1] CV D Si 02 0, 15 on the 81 substrate
A 5102 film consisting of μm/BPSG 0.35 μm was formed to a thickness of 0.5 μm, and connection holes with a diameter of 0.8 μm were formed by a known lamination lithography method. Next, molybdenum silicide was deposited at a thickness of 1000 Å using a known sputtering method, and a photoresist was applied on top of this.
It was coated to a thickness of 5 μm. After baking at 200'C, 300W. Oxygen plasma was generated under 0.3 Torr to etch Regime 1 for 2 minutes. Next, by ECR etching method using C12 gas,
The molybdenum silicide was etched and then ashed to completely remove the photoresist remaining inside the hole. Next, this substrate was coated with WF in a tungsden CVD apparatus.
10105c, l-1-12180s6c, temperature 420°C, total pressure 0.17 Torr, growth rate 400
Tungsten was selectively grown to a thickness of 0.3 μm at A/min. A laminated metal wiring of Ti/AL-8i-Cu was formed on this, and as a result, good substrate-wiring metal characteristics were obtained. [Example 2] A SiO film of 0.8 μm was deposited on the substrate on which the first layer wiring was formed.
It was formed to have a thickness of m. Next, as in Example 1, connection holes were formed, and then a film made of MO was formed to a thickness of 0.1 μm by sputtering. Next, in the same manner as in Example 1, photoresist was applied, baked, and resist 1 to back was performed for 2 minutes, leaving the resist only inside the hole. Next, the MO film was plasma etched using CI +02 gas to remove the MO film except for the holes. Next, after ashing, tungsten was selectively grown under the same conditions as in Example 1, and the inside of the hole was filled with tungsten. Next, AL/Si/Cu wiring was formed thereon to obtain a multilayer wiring structure. [Example 3] Creation of MOSFET In professional wrestling, after forming the diffusion layer part and the goo parts 1 to 1 on the substrate, SiO was used as an insulating film.
2, bias ECR method <conditions: microwave power 90
0 W,, flow rate ratio of S i l-14 and 02 1:2
, a bias power density of 1°17 W/cm 2 ) was deposited to obtain a planarized insulating film. The diffusion layer portion is 1 μm thick, and the gate portion is 0.5 μm thick. Next, MO was deposited to a thickness of 0.15 μm, and then, in the same manner as in Example 1, regimen 1 ~ coating, regime 1 ~ etch back, and MO etching were performed to coat the bottom and side wall of the connection hole with MO. A structure with an exposed membrane was obtained. When a tangent layer of 0°3 μm was selectively grown on this under the same conditions as in Example 1, both the deep connection hole on the diffusion layer and the shallow connection hole on the Goo1-polysilicon wiring were By selective growth of W, it was possible to embed it in the same way. In the above embodiment, molybdenum silicide and MO were used as the metals to be deposited, but any material that can grow W may be used, such as W itself, W silicide, SGe, transition metals, and their silicides. Of course, it may be a semiconductor. Further, the film thickness and forming method are not limited to those in the above-mentioned embodiments, and the point is that metal may be formed on the sides and bottom of the hole. [Effect of the Invention 1] Conventionally proposed tungsten growth techniques cannot be applied to filling connection holes in substrates, and even when used in wiring processes, they suffer from poor productivity. According to the present invention, a resist etch-back method is used to leave a metal thin film inside the hole (bottom, side surfaces) and tungsten is grown there, so that the above drawbacks can be solved. That is, the features of the present invention can be summarized as follows, and as a result, it becomes possible to manufacture high-performance large-scale and fine LSIs. (1) The metal thin film acts as a barrier and the encoragement 1
~ never occurs. Therefore, it becomes possible to apply the tungsten selective growth technique to the connection hole to the substrate. (2) Since the metal thin film acts as a barrier, the type of diffusion layer (
A constant amount of tungsten deposit can be obtained regardless of whether the tungsten is P type or N type. (3) Even if the connection hole has a high aspect ratio and is deep, the connection hole can be sufficiently filled by growing W equal to the radius of the connection hole. Therefore, the growth time can be shortened, and throughputs 1 to 1 can be improved. (4) As long as the connection holes have the same diameter, even if the connection holes have different depths, it is possible to fill the connection holes with one W growth.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the process of forming interconnects by conventional selective growth of tungsten. FIG. 2 is a diagram showing the corrosion caused when selectively growing tungsten in a contact hole. FIG. 3 is a diagram showing the wiring formation process according to the present invention. 1......Wiring metal 2...
......Insulating film 3...
......Connection hole 4...Tungsten 5...Wiring metal 6... ...3i board 7...
...... Encouragement 8...
・・・・・・・・・・・・RUUO3・・・・・・・・・
...Regist applicant: Nippon Telegraph and Telephone Corporation

Claims (1)

[Claims] A step of forming an insulating film on a substrate, a step of forming a contact hole in the insulating film, a step of forming a thin film of metal or its silicide or semiconductor, and a step of coating an organic polymer thin film.
A method for forming an electrode wiring, comprising at least the steps of etching, etching the thin film, and growing metal in the contact hole by chemical vapor deposition.