RU2264676C1 - Method for producing multilevel thin-film integrated circuits - Google Patents

Abstract

FIELD: microelectronics; multilayer structures on substrates made of various materials.

SUBSTANCE: proposed method includes formation of conductor patters in conductor layers and windows in insulator layers by way of photolithography and production of multilayer integrated circuit from conductor and insulator layers incorporating provision for inter-level commutation in the form of electrical connections obtained in insulator layer windows; integrated circuit is formed by sequential alignment of separate single-level thin-film boards and arrangement of permanent links in windows of insulator layers of these boards combining functions of inter-level commutation and physical fixation (mechanical connection) by means of, for instance, sections of conductor layers placed in relative contact condition provided according to desired layout above windows during formation of conductor patters; if physical strength of integrated circuit is found insufficient, its formation is accompanied by production of permanent links in additional windows of insulator layers to function as physical fixation only, for instance by microwelding conductor layer sections brought in mutual contact, these sections being made according to desired layout during formation of conductor pattern above additional windows without including them in mentioned pattern; in the process integrated circuit is formed through both types of windows whose axes are aligned during alignment of boards; for increasing number of boards being interconnected they are formed through windows whose axes in combined boards are spaced apart to reduce sag in conductor layer sections being connected including formation of permanent links in contacting conductor layer sections made in through windows of intermediate boards according to desired layout. This method is suited for use in production of multilevel integrated circuits with wide range of layer thicknesses and is compatible with commonly used integrated-circuit manufacturing technology.

EFFECT: facilitated manufacture, enhanced degree of integration, enlarged range of items produced, enlarged functional capabilities of method, reduced production expenses due to reduced cost of materials and equipment involved.

2 cl, 8 dwg

Description

The invention relates to the field of microelectronics, in particular, to the technology of manufacturing multilayer structures on substrates of various materials, namely multilevel thin-film integrated circuits with multilevel switching.

Known methods for the manufacture of integrated circuits with multi-level switching, which is a sequential multi-stage process of forming layers of conductors of different levels of switching with interlayer isolation and inter-level switching, including, for example, forming a layer of conductors of the first level of switching, applying a polyimide film on it for interlayer isolation, opening it windows for inter-level contacts by means of pulsed laser radiation and the formation of a second level switching method ohm vacuum metal deposition followed by photolithography to create a pattern of conductors (see. U.S. Patent №4508749, B 44 C 1/22, 1985 YG).

However, the presented typical analogue of the layer-by-layer build-up of a multilayer thin-film structure is characterized by the complexity of technological equipment and low manufacturing productivity.

There is also a known method of manufacturing two-level thin-film patch boards, including applying ion-plasma sputtering on a dielectric substrate layers of V-Cu-V-Al layers of the first metallization level, forming, by selective photolithography using positive photoresist, a pattern of conductors of the first switching level and using a negative photoresist of a protective mask with windows for transition contact posts followed by etching of the underlying protective (Al) and adhesive (V) layers above the conductive film (Cu) for making the windows themselves with intermediate processing of solder through the windows of the obtained copper contact pads by dipping them in a bath with solder, which leads to the formation of contact columns, then applying a dielectric film followed by processing with solder to melt the obtained contact columns by second immersion in the bath with solder, leading to rupture of the dielectric film and the growth of the columns by an additional amount, and then the deposition of V-Cu-V-Al layers to obtain a second level of metallization with photolithography graphically patterning the second switching level conductors (cm. A.S. No. 1358777, H 05 K 3/46, 1996).

This manufacturing method, which increases the yield, is characterized by technological saturation with production operations, low manufacturing productivity and a deterioration in the manufacturability of the process due to the need for processing with solder.

The closest to the claimed method for the technical problem to be solved is the manufacture of multilevel thin-film hybrid integrated circuits with improved quality characteristics and the technical process, the method is selected, which is the formation of a two-level pattern of conductors with interlayer insulation in the form of a polyimide film having windows for inter-level switching, including deposition by vacuum deposition on dielectric substrate of layers of chromium, copper, chromium, obtaining a pattern of conductors of the lower level of switching using photolithography, followed by the application of a technological layer of vanadium and the formation of windows in it at the interlayer isolation sections, which is formed by applying a layer of polyimide with opening windows for interlayer transitions in it and the subsequent removal of the technological layer of vanadium by selective etching, followed by sequential vacuum deposition continuous layers of vanadium and copper with galvanic build-up of a copper layer on the cleaned surface of the substrate, with a pattern of conductors of the lower level of switching interlayer insulation and interlayer for switching windows and the subsequent patterning of the upper switching level conductors by photolithography (see. RF patent No. 1816170, H 01 L 49/02, H 05 K 3/00, published in 2002).

This prototype method is also characterized by the general disadvantages of layer-by-layer building up of a thin-film structure, such as the complexity of the process and low manufacturing productivity.

The technical result of the invention is to simplify the manufacturing process and increase the productivity of manufacturing multilevel thin-film microcircuits, increase the degree of their integration and the efficiency of using the conductive layer, expand the product range by ensuring the operability of the proposed technology in a wide range of layer thicknesses of manufactured multilevel integrated microcircuits, universalize and expand the scope of the method due to its compatibility with traditional technology th chip manufacturing, as well as the depreciation of manufacturing by reducing costs for materials and equipment for the production of multilayer circuits.

The specified technical result is achieved by the fact that in the method of manufacturing multi-level thin-film microcircuits, which includes obtaining conductors in the conductive layers of the pattern and performing photolithography in the dielectric layers of the windows and forming from the conductive and dielectric layers a multilayer integrated microcircuit having inter-level switching in the form of electrical connections created in windows of dielectric layers, the microcircuit is formed by sequentially combining individual single-level thinly of ribbon boards with each other and creating in the windows of the dielectric layers of these boards one-piece connections combining the functions of inter-level switching - electrical connection and structural fastening - mechanical connection, by means of, for example, microwelding of sections of conductor layers brought into position of mutual contact previously provided topologically above the windows during the drawing of the conductors, and in case of insufficient structural strength of the microcircuit, its formation is accompanied the creation in additional windows of the dielectric layers of boards of one-piece joints, carrying out the function of only structural bonding, for example, by micro-welding the sections of the conductive layers brought into the position of mutual contact, previously topologically provided above the additional windows during the receipt of the pattern of conductors without including these sections in it, while microcircuit formation is carried out through both types of windows made with axes that coincide when the boards are aligned, and when the number of of interconnected boards - through windows with axes spaced in compatible boards to reduce the deflection of the connected sections of the conductive layers, including, if topologically necessary, the creation of permanent connections of the contacted sections of the conductive layers in the through windows in the intermediate boards.

To increase the reliability of contact during deflection in the windows of the connected sections of the conductive layers, the latter are partially coated with both types of windows, in order to increase the efficiency of the technology, the initial layer of conductors of single-level boards is used to obtain the sections to obtain the patterns of conductors, and to prevent the circuit of the intermediate layers of conductors boards one-piece connection of the contacted sections of the conductive layers through the through windows in the intermediate boards create under conditions of inlet di The electrical layer in these windows.

In a specific implementation of the method, the initial single-level thin-film boards are obtained by vacuum spraying a conductive metal, for example, copper, chromium, gold and others onto a polyimide film or by applying varnish to a foil of a conductive metal, followed by photolithography to obtain a single-level topology of the boards.

The proposed method provides for connecting the boards to each other in the microcircuit design with an additional increase in the structural strength of the microcircuit by applying adhesive compositions between the boards or enhancing the interconnection of the boards between each other by dipping the formed multilayer microcircuit in a polyimide varnish, followed by photolithography of the microcircuit's surface to reveal areas for mounting the mounted components in it and imidization of polyimide varnish.

The proposed method allows the development of the technology of the claimed manufacturing of microcircuits, in accordance with which the formation of microcircuits begins with the connection of single-level thin-film boards with a single or double-sided board, made on the basis of a common rigid dielectric substrate for the entire multi-level microcircuit, for example, ceramic, anodized aluminum, fiberglass or metal substrate, and continue to connect, respectively, on one or both sides of this substrate with the passage of a fragment of one an ovine thin-film board through holes made in a common rigid substrate, or metallization of such holes to ensure continuity of inter-level switching of the microcircuit, as well as a manufacturing option, in accordance with which the formation of a multi-level microcircuit is completed by connecting additional single-level thin-film boards to both interconnected single-level thin-circuit boards boards made on the basis of a rigid substrate and equipped with means for mechanically connecting a multilayer microcircuit, n For example, structural fasteners to enhance the fastening of boards around the perimeter of the microcircuit design.

Figure 1 shows a diagram explaining the manufacture of multi-level thin-film microcircuits in accordance with the claimed method:

a - in the case of combining and connecting two single-level thin-film boards,

b - in the case of combining three single-level thin-film boards and connecting to each other through through windows with the inlet of a dielectric film in them,

c - in the case of connecting single-level thin-film boards in an amount of more than three with stepwise spacing of the window axes at the switching levels,

d - in the case of connecting boards with a combination of diversity and coincidence of the axes of the windows in the compatible boards;

on figa is a diagram explaining the manufacture of multilevel thin-film microcircuits in accordance with the claimed method in the case of forming a microcircuit based on a common rigid dielectric substrate with a single-level thin-film circuit boards connected to it and between them on both sides of it,

on figb is a diagram of the technological operation of manufacturing the microcircuit shown in figa, which consists in passing a fragment of a flexible single-level thin-film board through an opening in a common rigid substrate;

figure 3 is a specific example of a connection with a single-sided board (a) made on the basis of a ceramic substrate, single-level flexible thin-film varnish-foil boards (b) and (c), with offsets (d, e) of the image of the strip - element above the window in the dielectric layer Boards for one-piece connection.

The inventive method is as follows. In single-level thin-film boards 2-5 (see figa-d), as well as boards 12-19 (see figa), containing layers - conductor 6 and dielectric 7 and representing, for example, a metallized polymer film obtained as a result of applying a conductive metal, for example, copper, chromium, gold and others to a polyimide film or a varnish-foil film obtained by applying a varnish coating to a conductive foil, in the dielectric layers 7 of these boards there are windows 8 for subsequent permanent connections of boards 1-5 (see figa-d), and also boards 12-20 (see Fig. 2a) are interconnected, and if there is a topological need for intermediate single-level thin-film boards, through windows are made for permanent connections of several boards together, in particular, through the board 2, a through window 9 with a dielectric inlet 10 layer 7 of the board 3 for one-piece connection of the boards 1-3 with each other using the inlet 10 to prevent the circuit of the conductive layer 6 of the board 2 with the conductor layers 6 of the boards 1-3 during subsequent creation of the one-piece connection in window 9 (see figb). At the same time, while receiving the pattern of conductors in single-level boards 2-5 and 12-19 above the windows 8, sections 11 of the conductor layer 6 are saved, in the form of initial strips - elements 29 and 30 for subsequent permanent connections of such boards (see Fig. 3d, d ) with the inclusion in the drawing of conductors of sections 11 in the form of strips - elements 29 for integral connections of boards, combining the functions of inter-level switching and structural fastening, and without the inclusion in the drawing of conductors of sections 11 in the form of stripes - elements 30 for integral connections of boards, bearing function only structural bonding.

Then, boards 1-5 prepared for joining in a multilayer structure (see FIGS. 1a-d) are alternately aligned, bringing their sections 11 of the conductor layers 6 in the windows 8 into contact, and created in them in the course of sequential alignment of the boards by means of, for example, microwelding, one-piece connections of sections 11 of adjacent boards to each other, starting from the connection of section 11 of board 2 with the conductive layer 6 of board 1, including options for creating a one-piece connection of boards 1-3 through the through window 9 (see fig. 1b), and stepwise spacing of windows 8 connect s boards 1-4 to reduce the deflection of the connected sections 11 (see figv).

To increase the structural strength of the microcircuit during its formation by alternately creating permanent connections of single-level boards 1-5 to each other, it is possible to apply adhesive compositions between the boards or to increase the operational safety margin of the microcircuit after forming its multilayer structure by means of the permanent connections of the boards 1-5 to each other, the microcircuit dipped in polyimide varnish followed by photolithography of the surface of the microcircuit to open sections in it for mounting mounted components and imidization of the polyimide varnish by exposure to ultraviolet rays (in Fig.1-3, both operations are not reflected).

The proposed method involves the serial connection of single-level thin-film boards 12-19 (see figa), starting with the connection with a double-sided board 20, made on the basis of a rigid dielectric substrate 21 common to the entire multi-level microcircuit, for example, ceramic, anodized aluminum, fiberglass or metal substrates, on both sides of this substrate, ensuring continuity of commutation of a multi-level pattern of conductors by passing a fragment 22 of a flexible single-level thin-film plate s through the hole 23 in the substrate 21 (see fig.2b) or metallization of such a hole in the initial stage of manufacture, as well as the completion of the formation of a multi-level microcircuit by attaching additional single-level boards made on the basis of a rigid substrate to both interconnected single-level thin-film boards and equipped with means for mechanically connecting the multilayer microcircuit, for example, structural fasteners to enhance the fastening of the boards along the perimeter of the microcircuit structure (Fig.1-3 second operation is not reflected).

In a specific example of the manufacture of a multilevel microcircuit (see Fig. 3), the ceramic substrate from Policor 22XC with dimensions 60 × 48 × 1.0 mm with vacuum deposition and photolithography using a one-sided pattern of copper conductors 24 was taken as the initial board (a) (or aluminum) and sections 25 of the conductor layer for structural bonding with attached boards, as well as with drilled holes 26 to align the connected boards. For connection with the board (a), thin-film boards (b) and (c) are prepared from the material DLPM (NU 037102 TU), which are a varnish-foil film with a thickness of the conductive layer of copper (or aluminum) 30 μm and a dielectric layer - polyimide film 25 μm with photolithography obtained on these blanks and etching with a pattern of conductors 24 and windows 27 for inter-level switching combined with structural bonding, and windows 28 for bonding without switching while storing strips of elements 29 and 30 above both types of windows odnikovogo layer for subsequent welding and installation of windows 31 under the discrete elements of the chip.

To form a multilayer structure of the manufactured microcircuit (three layers are shown in Fig. 3 to confirm the industrial applicability of the proposed method), the tooling is simple and reliable and is (not shown in the figures) a housing with guide rods for holes 26 for combining blanks with simple devices for bringing into contact the connected sections of the conductive layers in the form of strips - elements 29 and 30 and their microcontact welding through windows 27 and 28 on a type installation USIMIM-2 with control using a microcontroller based on the processor AT 89 LS 8252 "Atmell"

The proposed manufacturing method is currently at the stage of industrial development and will increase the degree of integrity of inter-level microcircuit connections, including by increasing the number of connected blanks to 15 or more and the productivity of manufacturing multilayer integrated structures of 1.5-2.0 times cheaper technology manufacturing 3-4 times in comparison with the prototype.

Claims (8)

1. A method of manufacturing multilevel thin-film microcircuits, including obtaining conductors in the conductive layers of the pattern, performing in the dielectric layers of the windows by photolithography and forming from the conductive and dielectric layers a multilayer integrated microcircuit having inter-level switching in the form of electrical connections created in the windows of the dielectric layers, characterized in that the microcircuit is formed by sequentially combining individual single-level thin-film boards with each other and creating in the windows of the dielectric layers of these boards of permanent connections, combining the functions of inter-level switching - electrical connection and structural fastening - mechanical connection, for example, by means of microwelding, brought into position of mutual contact of sections of conductive layers previously topologically provided above the windows during drawing conductors, and in case of insufficient structural strength of the microcircuit, its formation is accompanied by the creation of additional windows dielectric layers of boards of permanent joints, carrying out the function of only structural bonding, for example, by means of microwelding, brought into position of mutual contact of sections of conductive layers, previously topologically provided above additional windows during the drawing of conductors without including these sections in it, while the formation of microcircuits is carried out through both types of windows made with axes that coincide when the boards are aligned, and when the number of connected boards increases, through windows with an axis spaced in compatible boards to reduce the deflection of the connected sections of the conductive layers, including, if topologically necessary, the creation of permanent connections of the contacted sections of the conductive layers in the through windows in the intermediate boards. 2. The method according to claim 1, characterized in that the sections of the conductive layers topologically provided above the windows of the dielectric layers in single-layer thin-film boards are partially coated with both types of windows and using single-level boards for this purpose during the preparation of the conductors . 3. The method according to claim 1, characterized in that the one-piece connection of the contacted portions of the conductive layers through the through windows in the intermediate circuit boards is created under the conditions of the inlet of the dielectric layer in these windows to prevent short circuiting of the conductive layers of the intermediate circuit boards. 4. The method according to claim 1, characterized in that the initial single-level thin-film boards are obtained by vacuum deposition of a conductor metal, for example copper, chromium, gold and others, onto a polyimide film or by applying varnish to a conductor metal foil. 5. The method according to claim 1, characterized in that the boards are interconnected with an additional increase in the structural strength of the microcircuit by applying adhesive compositions between the boards. 6. The method according to claim 1, characterized in that the connection of the boards with each other is supplemented by dipping the formed multilayer microcircuit into a polyimide varnish, followed by photolithography of the surface of the microcircuit to open areas for mounting components and imidizing the polyimide varnish. 7. The method according to claim 1, characterized in that the formation of the microcircuit begins with the connection of single-level thin-film boards with a single or double-sided board, made on the basis of a common rigid dielectric substrate for the entire multi-level microcircuit, for example ceramic, anodized aluminum, fiberglass or metal substrate, and continue to connect, respectively, on one or both sides of this substrate with the passage of a fragment of a single-level thin-film board through holes made in a common rigid substrate, or metallization of such holes to ensure continuity of inter-level switching of the microcircuit. 8. The method according to claim 1, characterized in that the formation of a multi-level microcircuit is completed by attaching additional single-level boards made on the basis of a rigid substrate and equipped with mechanical connection of a multi-layer microcircuit, for example, structural fasteners, to interconnected single-level thin-film boards from two sides of them. to enhance the bonding of boards along the perimeter of the microcircuit design.

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