JPS63500346A - How to make layered structures - Google Patents

Abstract

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

Description

[Detailed description of the invention] The present invention relates to a method of making a layered structure for an integrated circuit, and more particularly, to a method of making a layered structure for an integrated circuit. Concerning horizontal layered structures containing several electrically connected metallization layers It is.

Previously proposed methods for making integrated circuits, especially 1-micron integrated circuits, Metallization that forms passages between shaped structures, i.e. metal-to-metal connections. The process involves the formation of a layered structure containing various levels of layers. phase between layers of metal The method for making interconnections consists of forming metal pillars where passages are needed (we co-pending European Patent Application No. 0129389) and below. A layer of dielectric material is deposited on the periphery of the column to insulate the next metal layer from one metal layer. It includes the steps of

The method described above, which includes forming a metal pillar, deposits a barrier layer on an underlying metal layer. The method includes depositing a columnar layer of metal over the barrier layer. underlying metal layer, The wall layer and columnar layer are then etched according to the first mask pattern. columnar The layer is then etched according to a second mask pattern to form the vias. Make sure to leave the pillars. The purpose of the barrier layer is to prevent the plastic used to erode the columnar layer. The goal is to prevent the Zuma from affecting the underlying metal layer. This is below It helps to ensure that the thickness of certain metal layers is accurately defined.

However, horizontal layered structures containing columns made using such barrier layers are It is disadvantageous in that it exhibits relatively poor electromigration resistance in the glabellar area of the body. In addition, The use of such a barrier layer has the disadvantage of complicating the method described above.

One aim of the invention is to improve electromigration resistance properties between metallization layers. At the same time, it is also possible to eliminate the need for a barrier layer.

In accordance with the present invention, the step of depositing a first layer of metallization onto a substrate; The first layer of metallization and the columnar layer of a different conductive material are added to the first layer of metallization. depositing a first layer of metallization and a columnar layer on a first layer; Erosion according to the mask pattern and the first layer of metallization corroding the columnar layer with a corrosive agent that resists according to a second mask pattern; and depositing a dielectric layer, and depositing a columnar layer that has not been corroded by the corrosive agent. A step of corroding the dielectric layer to expose it and also touching the exposed columnar layer. depositing another layer of metallization. A method of making a layered structure is provided.

The layered structure made according to the present invention has a high resistance to electromigration between layers of metallization. It has the advantage of improved properties and simpler manufacture of the structure. .

The first layer of metallization can be aluminum and the columnar layer can be aluminum. May be made of refractory metals such as ungsten.

Layered structures with several layers of metallization are repeating the above method until the layer is the final metal layer of the required layered structure. assembled by.

Another layer of metallization is then etched to remove the unwanted metal. Sometimes.

Brief description of the drawing The invention will now be explained in more detail by way of example with reference to the accompanying drawings, in which: FIG.

Figure 1 shows a structure with a columnar layer of metal deposited over the metallization. .

FIG. 2 shows the structure of FIG. 1 after erosion by the first mask pattern.

Figure 6 shows the structure of Figure 2 after the metal columnar layer has been etched by the second mask pattern. Show the creation.

Figure 4 shows a dielectric layer attached to the surface of a metal columnar layer and corroded to expose it. Figure 5 shows the structure shown in Figure 6 after the corrosion has been deposited on the structure shown in Figure 4. Another layer of subsequent metallization is shown.

From the drawing, it can be seen that a first layer 2 of metallization is placed on a substrate 4, such as a silicon substrate. It is attached. A columnar layer 8 of conductive material such as metal is then applied to the metallization. Deposited over the first layer 8, the structure shown in FIG. 1 is provided. metallize The first layer 8 of the solution is preferably a 1 micron thick layer of aluminum. . Aluminum can be pure aluminum or doped with silicon or copper. It can be made of aluminum. The metal columnar layer 8 is a metallization sheet. an inherent electromigration resistor that can be dry etched selectively with respect to the first layer 2 of the It is preferable that it be made of a metal with relatively high resistance. Conductive materials like tungsten It may be a refractory metal or made of gold or chromium. Separately, conductive materials may be made of semiconductor materials such as doped silicon.

Columnar layers made by such methods are sensitive to the relatively high electromigration resistance of such metals. It has the advantage that there is less risk of electromigration failure due to

Although not shown, the first mask pattern is formed on the surface of the metal columnar layer 8. ing. The first mask pattern is the metallization in the composite layered structure. represents the interconnection pattern required for the first layer 2 of . Structure shown in Figure 1 is then eroded by anisotropic plasma etching producing the structure shown in Figure 2. . It can be seen that the structure shown in FIG. 2 does not include any lower cutouts.

The metal columnar layer 8 is formed using plasma using fluorine such as carbon tetrafluoride. and the first layer 2 of the metallization (formed from aluminum) for example, using a plasma containing chlorides such as carbon tetrachloride eaten. To obtain a planar surface, polyimide is spun onto the surface of the metal columnar layer 8. may be scanned. This planarization step is not essential and can be omitted. I don't mind. The metal pillars 10 in FIG. 3 form the passages of the final structure. It can be assembled. This is done by attaching a second mask pattern to the structure in Figure 2. This is achieved by The second mask pattern requires metal columns 10. represents the area of the columnar layer 8 of metal. The mask pattern can be any known photoresist. The first mass is a resist material that extends slightly beyond a predetermined area of the metal columnar layer 8. between adjacent metal tracks defined in the columnar layer 8 of metal after corrosion by a pattern of doesn't grow. This overlap of mask patterns adversely affects the formation of the metal pillars 10. Each metal column 10 does not blur the metal column layer 8 below the mask pattern. This is because it is formed as a part of the

The columnar layer 8 of metal is made of a material such as carbon tetrachloride that the first layer 2 of metallization resists. plasma etching according to a second mask pattern using a suitable etchant. this Since corrosive agents do not attack the first layer 2 of metallization, the columnar layer 8 of metal The first layer of metallization is etched downward to the first layer 2 of the metallization. The metallization pattern in 2 is created and the metal precisely matched to it. The structure of FIG. 3 having pillars 10 is created. The metal columnar object 10 is made of metallizer. used to form the metallization pattern in the first layer 2 of the The parts are precisely aligned as they are made during corrosion.

The dielectric layer 12 is applied to the sixth It is now deposited onto the structure shown in the figure. The dielectric layer only surrounds the structure in Figure 6. , so that the pillars 10 are surrounded and covered by the material of the dielectric layer. As a result, a planar surface is provided on the metal post 10. dielectric layer 12 Is it a polyimide material such as that sold by Hitachi under the trade name PIQ? It is desirable that the

The dielectric layer is then plasma etched to expose the top surface of the metal post 10. dielectric Layer 12 may be etched using a carbon tetrafluoride and oxygen plasma, or A suitable device may be included in the plasma chamber to expose the surface of the metal column 10. This ensures that the corrosion process ends as soon as the corrosion process is completed. The composite structure is shown in Figure 4. The exposed surface of the metal post 10 constitutes a connection to the next metal layer.

In fact, the substrate 4 is not flat and varies in height by an amount comparable to the thickness of the metal layer. It has a surface topographic map. Therefore, some pillars 10 stand taller than others; The tops of these are exposed at the beginning of the corrosion stage of dielectric layer 12. The highest of the lowest columnar objects 10 The highest column protrudes until the top is exposed. The corrosive agent for the dielectric layer 12 is removed. In the case of fluorine-oxygen chemistry, the corrosive also corrodes the pillars 10. Fluorine dielectric layer 12 and pillars 10 if a suitable mixture of and can be corroded at an equal or approximately equal rate. Therefore, columnar object 1 By using a corrosive agent for dielectric layer 12 that also corrodes can be improved.

Another metal layer 14 is then deposited over the structure shown in FIG. metal layer 14 contacts the exposed surface of the columnar object 10 in the dielectric layer 12 . Seen now As shown in FIG. and the metal layer 14, i.e. the pillars 10 are connected to the metal layer 2. and 14.

If layered structures require two levels of metallization, one more The metal layer 14 becomes the final metal layer of the structure.

A final mask pattern is formed on metal layer 14, and metal layer 14 is formed on the final mask pattern. Another level of metallization, corroded according to the pattern Unwanted metal can be removed from the field area.

If more than two levels of metallization are required, a columnar layer of metal 8 may be used. A columnar layer of metal may be deposited on top of another metal layer 14. At that time, the operating The sequence is repeated until the desired multi-V bell metallization structure is created. , the final metal layer is another metal layer 14 in conjunction with the two-level metallization structure. Corroded to remove waste metal in the field area as described above. Ru.

The method of the invention is characterized in that the metal is precisely matched to the metallization of the first metal layer 2. By providing a passageway in the form of a pillar 10, the largest passageway is provided in the smallest available space. size is achieved.

The embodiments of the invention described above with respect to the accompanying drawings are given by way of example only, It should be acknowledged that some deformations are created. Thus, for example, other than aluminum materials can be used for the metallization layer. In addition, more than tungsten conductive materials such as gold, chromium or semiconductors such as doso-treated silicon body material can be used for the columnar layer. For dielectric layer 12, silicon dioxide polyimides, such as silicon nitride, silicon oxynitride, and other organic materials. Other materials can be used. However, depending on the specific material used, Adequate deposition and planarization processes should be used.

Furthermore, the fabrication method for layered structures can be applied to gallium arsenide structures if the materials are selected appropriately. Can be applied.

G2 Procedural amendment (voluntary) April 1986/, 3? Day

Claims (15)

[Claims] 1. forming a first layer of metallization on the substrate; A columnar layer of a conductive material different from the first layer of metallization is placed on top of the first layer of metallization. depositing the first layer of metallization and the columnar layer in a first mask pattern. The first layer of metallization is corroded according to the turn and the second layer of metallization is corroding the columnar layer with a corrosive agent that resists the dielectric layer according to the pattern; etching the dielectric layer to expose the columnar layer; and exposing the dielectric layer. Another layer of metallization is formed in contact with the columnar layer. A method of making a layered structure comprising: 2. Claims characterized in that the first layer of metallization comprises aluminum. The method described in Scope 1. 3. The first layer of metallization is silicon or copper doped aluminum. 3. A method according to claim 2, characterized in that it contains Ni. 4. Claims 1 to 3, wherein the columnar layer contains a refractory metal. Either method requires one entry. 5. According to claim 4, the refractory metal contains tungsten. How to do it. 6. 5. A method according to claim 4, characterized in that the refractory metal comprises gold. 7. A method according to claim 4, characterized in that the refractory metal contains chromium. . 8. Claims 1 to 3, characterized in that the columnar layer contains a semiconductor material. Any of the methods described in one section. 9. Claim 8, wherein the columnar layer comprises doped silicon. Method according to section. 10. Claims 1 to 9, wherein the dielectric layer contains polyimide. Method by describing any of the sections in one section. 11. The first layer and columnar layer of metallization are anisotropic plastic containing chlorine. Claims 1 to 10 characterized in that the material is corroded by a Zuma corrosive agent. Method by describing any one of the sections. 12. Corrosive agents that corrode the columnar layer resisted by the first layer of metallization are Claims 1 to 10, characterized in that the plasma contains plasma containing elements. Method by describing any of the sections in one section. 13. The caustic agent used to erode the dielectric layer to expose the columnar layer is as described above. Claim characterized in that the dielectric layer and the columnar layer are corroded at substantially equal rates. A method according to any one of the items 1 to 12 in the range of 1 to 12. 14. Claim 1, wherein the corrosive agent contains a fluorine-oxygen compound. The method described in Section 4. 15. Another layer of metallization becomes the final metallization layer of the structure claim 1, further comprising the step of selectively repeating the method until A method according to any one of Items 1 to 14.