TW508735B - A method to create a controllable and reproducible dual copper damascene structure - Google Patents

Abstract

A new method is provided to construct a copper dual damascene structure. A layer of IMD is deposited over the surface of a substrate. A cap layer is deposited over this layer of IMD, the dual damascene structure is then patterned through the cap layer and into the layer of IMD. A barrier layer is blanket deposited, a copper seed layer is deposited over the barrier layer. The dual damascene structure is then filled with a spin-on material. The barrier layer and the copper seed layer are removed above the cap layer; the cap layer can be partially removed or can be left in place. The spin on material remains in place in the via and trench opening during the operation of removing the copper seed layer and the barrier layer from above the cap surface thereby protecting the inside surfaces of these openings. The spin-on material is next removed from the dual damascene structure and copper is deposited. The cap layer that is still present above the surface of the IMD protects the dielectric from being contaminated with copper solution during the deposition of the copper. The excess copper is removed using a touch-up CMP. The cap layer over the surface of the IMD can, after the copper has been deposited, be removed if this is so desired. As a final step in the process, a liner or oxidation/diffusion protection layer is deposited over the dual damascene structure and its surrounding area.

Description

508735

V. Description of the invention (1) Background of the invention: The scope of the invention: This invention is related to the manufacture of integrated circuit components, and in particular it is a type that can reduce dishing and rotten names in a dual damascene structure. Effect method. Related technical description: In the fabrication of semiconductor integrated circuits, it is common to use contact f (conntact) or vias to connect different metal layers to form an interconnect metal layer structure. First, in the first step, a first layer or a bottom-most interconnecting gold layer is formed, and then the first layer covers it. The first metal layer is usually in contact with the active area of the wafer substrate, but it is not limited to this contact. The first layer can also be in contact with the conductor and form a larger multi-wafer junction with other components. The lower metal layer is conducted by the metal of the open window in the middle of the second layer. The previous technology focused on forming the first interconnecting metal layer and then the second layer covering it. This technology must be used in the crystal. There are already active regions on a circular substrate ^, and these active region elements include a double-electrode electron beam, a gold body (M0SFET), and a doped region that contains the open-cell handle, and the rest of the body # ^ ^ The surface of the 4-wire metal layer connected to the input and output ends of the element may be covered by an insulating layer. ★ The substrate is first Λ-layered, and on top of this oxide layer, the interconnecting metal is traditionally micro-optical optical technology. Layer and open window, ^ ι > 0Θ Μ ^ Gu Yin case is defined on it. 3 After the opening of the opening ®, it may be overlaid to strengthen the metal's adhesion ability, and then re / adhesive: glUe layer, to prevent the subsequent process, = add a layer of barrier layer coffee Branch enters or diffuses from the base. Paragraph 508735 V. Description of the invention (2) —-· The barrier layer has different materials, such as · titanium / titanium nitride: tungsten, titanium tungsten alloy / titanium, or titanium tungsten nitride, silicon nitride, button, molybdenum, etc. . In the final stage of making the first layer of metal interconnects, the opening window needs to be filled with metal, which is usually made of / Lu: tungsten or copper. The choice of material depends on the requirements of line width, aspect ratio of the open window and surface flatness. / Because there are some limitations in the production of metal wires for interconnecting metal layers and it is easy to cause problems, recently, copper has been changed to process applications. It has low resistance ^ high ^ electromigration ability ^: ^ ⑽⑽ order ... ⑻ and Reduced stress produces two advantages. However, copper also has some process shortcomings, and it is easy to diffuse in silicon dioxide and oxygen-containing polymers. This makes it possible for copper to diffuse into polyimide compounds during high-temperature processes, resulting in a combination of copper and oxygen, resulting in severe corrosion. This phenomenon leads to a reduction in adhesion, peeling, voids, and component failure. If copper diffuses into the silicon dioxide layer,-it will make the dielectric layer conductive and reduce the dielectric strength of the silicon dioxide & :: layer is required. Silicon nitride is one of the materials of the barrier layer, but the dielectric constant of silicon nitride is higher than that of silicon dioxide, which is the application of silicon nitride. Obstructed, because copper is very difficult to etch in the reactive ion etching (RIE) process = to use chemical mechanical polishing method, in order to grind copper at a high rate =, ^ There are scratches on the metal wires, by improving the copper The etching ratio increases the etching rate of steel, but increasing this material results in isotropic j. The buried copper wire is thus engraved and a dish-like depression occurs. In addition, the difficulty in the remaining gas length is the sensitivity of copper to oxygen, which hinders the development of copper interconnects. 'Because the photomask process is completed, the photomask pattern is transferred' ^ ^ to crystal

V. Description of the invention (3) On-chip photoresist must not be easily produced by copper-containing processes. The heat removal in the clothes brother, so that the eyes of the industry widely used single-embedded mountains, this is due to the nano-scale large-scale integrated electrical system, to make steel wires (Plug) must be etched very deep, dry etching dare Structural plugs have recently used copper as a conductive metal wire; methods can meet this need. An oxygen semiconductor (c_ ☆ layer of gold 瓜 was implanted into the m-structure early, and a wafer stone substrate, often referred to as wafer wafer, was first formed on the surface, and then the image was used to deposit an internal dielectric layer (Intra Uvel Dielectl: ie Phase deposition technology siliconized silicon dioxide, carved out on the surface of the dielectric layer using the image of the nick, such as the second channel arench). The phantom ion post-etching technology will be used to chemical vapor deposition or metal heat flow method After the surface of the dielectric layer is flattened, = 成 Ϊ = ,,, .. The structure was implanted early using reactive ion engraving for planarization. Nowadays, chemical mechanical polishing has been widely replaced. Extension of the single-embedded process For the dual-embedded process, there are thousands of open windows on a dielectric material such as silicon dioxide, which are used to connect the metal wires and the vias. At the same time, the metal is filled in these open windows. Single embedded structure It is a copper process in which some trenches are formed in the insulating layer or the dielectric layer to form interconnects. The double-embedded structure is a multiple interconnect process. In addition to the trenches in the single-post-in structure, it also forms a connected dielectric. Layer hole. Double-embedding process roughly ^ three : 1) depositing a first three consecutive dielectric layer, the intermediate layer is an etch stop layer, a stop layer of which may be S i N, with the upper and lower layers is silicon dioxide. After the deposition of these three layers 508735, microlayers are used, and the same method is used to generate three layers to stop the standard. However, 5. Description of the invention (4) After the dielectric layer is etched through this layer, the etching layer pattern is paired, and the first transfer is deposited. It was not until the crystal that the double-embedded trench and the interstitial hole encountered some difficult-to-etch rates, and the origin line profile was relatively shallow. The process is difficult to produce, gold and silver, but deep, but it is used in polycrystalline seconds. The previous compound was chemically softer than the copper compound. In the process, it will cause: ’to form an interlayer and then etch the stop layer of gold II. 2) Another type of trench pattern is formed on the dielectric pattern using the formed metal: the next step is to deposit three layers of dielectric layer stopper, and then deposit the hole pattern of the dielectric layer, and then deposit the dielectric layer on the chip thereon. The structure is simultaneous problem-solving, which is evenly interconnected. Due to the fact that the internalization is not easy to sink and the crane's process makes the mechanical research mentioned in the chapter compare the hard grinding rate of the surface shadowing technology with the metal layer and the dielectric layer, and then the oxide stone is exposed and the light groove I is finished. Reduce the vapor deposition learned from the thin film line contacts on the wafers and some of the component connections. The dish-shaped grinding process made of copper has a fast speed. Because the disc conversion pattern is generated, the vias are first holed. 3) I insect is carved after I insect is engraved. There are few structures in the process. The depth of the deposition is difficult. There are characteristic rulers in the center. The metal used in these techniques is metal. These materials are metal-concave and intermediate. Non-uniformity is used to control deeper inches. There are more metal materials that can resist the resistance of the material and the corrosion rate of the current grinding. The titanium and rotten insects because of it but it must be refined to make the profile, small vertical The quality and the resistance of the gas phase are different from those of the barrier layer, which is caused by the abrasive compound. The wire channel is allowed to accurately control the etching in the process. The gold on the wafer is close to the side of the wafer. The aspect ratio is as good as a splash. The deeper penetration of copper is generally higher than copper. Qin and Qinhua caused by copper and titanium. By slow;

508735 V. Description of the invention (5) The present invention provides a method for reducing the dish-like depression and corrosion phenomenon on the surface of _ 矣 & 卩 久 & ^ ^, m. Flatness and uniformity. ), Depositing a copper crystal layer (Seed layer metal / Situ glass (write)) on the / V gold A " electrical layer (IMD) and filling the opening window to remove the copper crystal layer above the inner lightning μ = s, The spin-coating material is removed and the selective helmet method is used to 'deposit copper in the open window, while the barrier layer and coating: = also part of the invention' ... discussed in the article. Example Technology US Patent No. 5674787, awarded A process for double-embedded interconnecting, zirconium, and electro-selective electroless plating of copper with Zhao 0 et al. US Patent No. 5 1 83795, Ting et al. Describe selective electroless copper electroplating using photoresist to remove copper crystal layers US Patent No. 5705430, Avanzino et al. Double-embedded structure filled with a sacrificial mesopore. Said US Patent No. 5817572, Chiang et al. Described the dual-embedded process US Patent No. 566337, Koh et al. The deposition and filling of the spin-coated material produces a low-electrode process. The present invention mainly provides a method to reduce the dish-like depression and corrosion phenomenon on the surface during the double-entry process of copper wires. Another theme is to improve the overall flatness and uniformity of the surface According to these two themes, the present invention provides a new method to generate a double-introduction structure. The inner metal dielectric layer is first deposited on a silicon substrate, and a cap layer is deposited over the inner metal dielectric layer to double-embed. Structure (via via

508735 V. Description of the invention (6) and trench opening Chinky barrier layer deposited on the barrier material can be completely with copper crystal layer, the layer and copper crystal layer are used to protect the opening and the copper which is selected to protect the inner gold is made by) Deposited on a double layer. When the coating is partially or partially solidified, the internal non-electrolysis of the dielectric layer and the window is a dielectric layer. The chemical mechanism can be removed. In this process, a lining layer F and an inner metal dielectric layer are deposited in the surrounding area, and the button is inserted into the structure and above the cladding layer, and then the double-injection structure is coated with spin coating material to remove the inner metal dielectric. Above the layer can be partially retained or removed ^. ♦ The spin-coated materials in the holes and trench openings need a surface to avoid damage. Removal electroplating method deposits copper in the open window, so as to avoid contamination during the process of copper electroplating. When the steel deposition is completed, in the last stage, we are in a double-liner or gasification diffusion protective layer. Or tungsten or copper crystal layer. This spin-coated barrier layer is kept in addition to the barrier. When coating the material, the coating is dyed, and the structure and drawing number of the overcoat layer are simply explained. 10 Metal layer 12 Interlayer 14 Channel trench 16 Dielectric layer 18 Overlay Layer 20 Barrier layer 22 Steel crystal layer 24 Spin-coating material 26 Electroless copper 30 Evaporation diffusion protective layer Detailed description of the invention

508735

Referring to Figure 1, the internal gold coating 18 is deposited under the conditions of internal gold as a coating for chemical mechanical polishing removal, about 100 to 300 angstroms, the dielectric layer, the barrier layer and the copper crystal layer accelerate the selectivity. The structure and its adjacent area are shown in Figure 2 in the cross section of the cover. Double-embedded junction holes 12 and interposer holes 12 Note that the material of 3a is shown in Fig. 4a. A metal dielectric layer 16 is deposited over the metal layer 10 and over the metal dielectric layer 16. Like the copper barrier layer, it must be easily etched or another condition is that it must be deposited to an appropriate thickness. This coating can protect the inner metal crystal layer in the subsequent process, as described above. The barrier layer is deposited to avoid mutual diffusion of the dual inserts. The double-embedded structure of the layer 18 and the inner metal dielectric layer 16 includes interconnect lines or trenches 12 of the dielectric layer directly in contact with the metal layer 10. Figure 3b and Figure 3b are spin-coating materials for resist and Figure 4b are spin-coating materials for spin-on glass or poly. Figure 3a shows a cross-section view of copper crystal layer 22 and barrier layer 20 deposited on a double-embedded junction. . A resist spin-on material 24 is deposited over the copper crystal layer 22. The barrier layer 20 is deposited over the sidewalls and cladding layers 8 and the inner dielectric layer 16 of the dual-embedded structure, and the material can be titanium, tungsten, or a titanium-based material. Accumulated on the barrier layer 20. ^ The resist spin-on material is used to fill the embedded structure, that is, the interstitial hole 12 (Figure 2) and the interconnect 14. Another spin-coating material may be spin-coated glass or polyimide. These two spin-coating materials will be shown in Figures 4a and 4b. The spin coating material may be partially or completely cured in the subsequent process, and its main function is to protect the inner surface of the dual embedded structure. Eight

Page 12 508735 V. Description of the invention (8) Figures 3a and 3b show that if the spin-coating material 24 is a resist material, use oxygen or hydrogen-based plasma etching to remove the metal above the copper crystal layer 22 and the inner metal. Excessive spin-coating material 24 over the dielectric layer. After removing the spin-coating material, the copper crystal layer 22 and the barrier ^ 20 are removed by anisotropic dry etching (chlorine or fluorine-based plasma), and over-etched to Cladding layer 18. Since the resist has a high grade for the dry etching process, the resist 24 protects the underlying copper crystal layer 22. Another method is to selectively wet etch the copper crystal layer 22 using msO / CCL4 or HF / CHgCOOH, while hydrofluoric acid can selectively etch the button / tungsten / titanium-based barrier layer 2 without etching too much in the dual embedding A resist spin coating material within the structure. Figures 4a and 4b illustrate applications where the spin coating material is spin coated glass or polyimide. The excessive spin-coating material 24, the copper crystal layer 22 and the barrier layer 20 above the inner metal dielectric layer 16 can be removed by chemical mechanical polishing. When grinding to the coating layer 18, grinding can be stopped. Figure 4a shows the entire structure before grinding, and Figure 4b shows a cross-sectional view of the barrier layer 20, the copper crystal layer 22, and the spin-on material 24. When the copper crystal layer and the barrier layer above the cover layer 18 are removed, the spin-coated material 24 (Fig. 4b) still exists in the dual-embedded structure, and the spin-coated material 24 protects the copper crystal layer in the dual-embedded structure. twenty two. After the copper crystal layer 22 above the cladding layer 18, the barrier f20 and the spin-on material 24 are removed, the spin-on material 24 inside the opening is removed by a separate process. The process steps for removing the copper crystal layer, the barrier layer and the spin-coated material from the above are summarized in the following table. The first line is a method of spin-coating material used in the second line, and the second line is a method of selectively removing too much spin-coated material, copper crystal layer and barrier layer, and the third line is a method of removing the spin-coated material in the dual embedded structure.

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The first-> column 7 is for removing the resist spin coating material above the copper crystal layer. The item called y is for removing the copper spin layer and the resist spin coating material above the barrier layer. T) δίΓ ~~ (Chlorine or fluorine) or wet worm (DMSQCCL ^

The third line Dry I worm (1 / nitrogen)

The process of removing the spin-coated material above the double-entry structure is a dry-remove process (shown in squares): the temperature is between 150 and 300 ° C, the etchant is as described in the table, the flow rate is between 10 and 300 0 SCCM, and the pressure Then it takes about 50 to loooG mT () RR 'money removal time is about 1 to 5 minutes. The process of removing the double-embedded internal resistance agent or polyimide spin-coating material is dry engraving, the temperature is 150 to 300 ° C, the etchant is hydrogen, the flow rate is 10 to 3,000 < 6 SCCM, and the pressure is about 50 to 1 0 0 0 0 mTORR, the etching removal time is about 1 to 5 minutes.

It should be noted in the manufacturing process that the coating 18 (at least partially) is still above the metal dielectric layer before the copper is filled into the dual embedded structure, which protects the inner metal dielectric layer from copper contamination. Figure 5 is a cross-sectional view of the selective embedded copper 26 deposited in a dual embedded structure. The key of the present invention is that during the selective electroless copper deposition process,

Page 14 508735

V. Description of the Invention (ίο) Contamination of the solvent in the process steel. Double-embedded in the structure, and a copper film is formed electrically, another product is' but this technology has not been used as a steel deposit. The advantage is that there will be no copper deposition. A continuous copper crystal layer can pass

The layer 18 protects the inner metal dielectric layer from electrical charges. The copper filling process using an electroless bond process cannot be used in this process because it is widely used as a technology for selective chemical vapor deposition of copper. Using selective electroless electricity mining In the surrounding area outside the open window of the double-embedded structure, copper plugs will over-deposit beyond the filling area as shown. Use chemical mechanical polishing to flatten and rot the surface, as shown in Figure 6. Since there is no conductive current, the electrolytic clock method cannot be used. FIG. 6 is a cross-sectional view of the double-embedded structure 26 after removing excessive copper above the cladding layer 18 by chemical mechanical polishing. Fig. 7 is a cross-sectional view of a complete double-embedded structure. The deposited layer 30 is a copper oxide diffusion barrier layer. This layer 30 is deposited over the cladding layer 18 as a protective layer. The material of the protective layer 30 is deposited on the entire surface. As shown in Figure 7, the present invention has several features: 1. When the material 'copper crystal layer and barrier layer is spin-coated on top of the coating, the spin-coated material still exists in the opening window of the double-embedded structure, so it is protected. The copper crystal layer in the structure. 2. The cladding exists to protect the inner metal dielectric layer from contamination from the selective electroless copper deposition process. 3 · After removing excessively deposited copper, the cladding layer can be removed or retained ′ as additional protection for the inner metal dielectric layer.

Page 15 508735 V. Description of the invention (11) 4 · The coating has the function of oxidative diffusion barrier to copper. Inflammation In general, dish-like depressions and corrosion effects are caused by copper and barrier ’, ground over-deposition, and different polishing rates of dish copper plugs. The sags and rot rhymes shown in Figure 5 did not occur. 0 ^ Although the present invention is described by using some illustrations, it does not mean that these illustrations are issued. Any modification related to the present invention is exclusive to the application of the present invention? Variations related to the day and month of this meal or

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Called η electricity 4 ~ the first ij plane. 508735 Brief description of the diagram. The first diagram is the inner gold layer above the metal layer. The second diagram is a cross-sectional view of the double embedded structure formed in the cladding layer and the inner metal dielectric layer. The third diagram is a barrier layer. The copper crystal layer and the resist spin-coating material are deposited on the double-embedded structure. Figure 3b shows the removal of the excess. Figure 4a shows the cross-section of the double-embedded structure or the spin-coated material = the cross-sectional view of the resist spin-coated material. ’Earth barrier layer, steel crystal layer and spin-coated glass. Figure 4b is the double-embedded Mozilla of Figure 4a;) ¾ The cross-sectional view of the structure after removing the barrier layer, copper crystal layer and spin coating material. Figure 5 is a cross-sectional view of a dual embedded structure of copper deposited by selective electroless plating. Fig. 6 is a sectional view after chemical mechanical polishing. FIG. 7 is a cross-sectional view after the oxidation diffusion protection layer is deposited.

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Claims (1)

508735 VI. Scope of patent application1. A method for manufacturing a copper wire double-embedded structure on a semiconductor substrate, the steps include: providing a semiconductor substrate, the surface of which includes metal connection points to form an open window, which is used as In the double-embedded structure on the substrate surface, the opening window is formed with an inner metal dielectric layer, and the inner metal dielectric layer is covered with a coating; a diffusion barrier layer is deposited on the inner surface of the opening window and the surrounding area. A copper crystal layer is over the diffusion barrier layer; a spin coating is deposited over the copper crystal layer; the spin coating material above the opening window and the surrounding area is removed, and the spin coating material in the dual embedded structure is retained; Remove the copper crystal layer in the area around the open window; remove the barrier layer over the surrounding area; remove the spin-coated material of the double-embedded structured open window; use selective electroless deposition of copper on the double-embedded structure Inside the open window; removing excess copper above the double-embedded structure opening window by chemical mechanical polishing; and depositing an oxidation diffusion protection layer on the double-embedded structure and · The method of claim 1 Item Patent Application range surrounding surface area 02, the dual damascene structure having a via hole or a clad portion and a bottom portion of the metal wire or the upper end, and dielectric Page 18 508735 VI. Patent application layer The layer hole is connected to the connection point on the surface of the silicon substrate. The double-embedded structure opening window is formed as follows: a first stop layer SiN is deposited on the surface of the substrate, and the stop layer is # 刻 介 层A worm-engraved stop layer at the time of the hole; a first dielectric layer is deposited over the first stop layer, the first dielectric layer forms an inner metal dielectric layer, and the first dielectric layer includes silicon dioxide material, and its function The dielectric of the vias; Plasma chemical deposition technology is used to deposit a second stop layer over the first dielectric layer. The Si N is used as a second etch stop layer and used as a stop layer when the double-embedded structure metal wire pattern is etched. A second dielectric layer is deposited. The electrical layer is above the second stop layer and serves as the dielectric of the metal interconnects. The coating is deposited over a second dielectric layer. A dielectric hole pattern is formed on the first dielectric layer, and it is engraved through A cladding layer, a second dielectric layer, a second stop layer, and a first dielectric layer; removing the first stop layer to form a dielectric hole pattern; and transferring through a photomask pattern, and etching through the cover layer, the first The two dielectric layers to the second stop layer form a metal wire pattern. 3. The method according to item 1 of the scope of patent application, wherein the material of the diffusion barrier layer comprises a combination of a group, a crane, titanium, and a compound thereof. 4. The method as described in item 1 of the scope of patent application, wherein the material of the spin coating material includes spin coating glass, resist, polyimide, or any suitable material. The spin coating material can be partially or completely cured. In the subsequent process steps, the inner surface of the dual embedded structure is protected. The method as described in item 1 of the scope of patent application on page 19, wherein the spin coating is p and the agent material is used to: ", the spin coating material on the upper surface of the opening window and the surrounding area, which is used Gas or hydrogen-based dry etching method; removing the copper crystal layer above the surrounding area and over-etching to the cladding layer, using an isothermal gas or fluorine-based dry I insect engraving process; * the barrier layer above the surrounding area, using oxygen Or hydrogen-based dry money engraving method; and removing the spin-coated material into the double-rear structure, using the hydrogen-based dry etching method omt Ming patent scope item 1, wherein the spin-coating is a random material, Used for: Spin-coating materials on the upper surface of the two openings® and surrounding areas, using oxygen or hydrogen-based dry etching methods; removing the surrounding area, the steel crystal layer above 1 ~ A, using hydrofluoric acid or hydrogen Fluoric acid mixture; Remove the upper and lower surroundings. The early layer of resistance, using the selective DMSO / CCL4 or hf / ch ^ cooh wet-etching method, is over-etched to the coating; and removed into the structure opening window The spin-coating material uses a hydrogen-based dry-cut method. The method of claim 1 Item range, wherein when the spin-spin-on glass coating containing, for: 508735 6. Scope of patent application: Remove the copper crystal layer and barrier layer above the surrounding area, and over-grind to the cladding layer, using chemical mechanical polishing method; and remove the spin-coated material in the double-embedded structure opening window, using hydrogen fluoride Acid or DHF or B 0 E base money etchants. 8. The method according to item 1 of the scope of patent application, wherein when the spin-coating layer contains polyimide, it is used to: remove the spin-coating material above the opening window and the surrounding area by chemical mechanical polishing; mechanical coating The dry side formula is the machine-to-bottom-product-integrity-based method for sinking and researching hydrogen copper and copper. This system has been used in the system and the middle,, its materials, and the barrier material method to block and apply the formula. Fang and., Xuan's process. The description of the layer-by-layer method Sex Fan School District; District Access. Faithfulness and Faith The first and second oxygens are removed and removed to remove the layer to sink the obstacle. The medium-resistance method in China removes it and removes it. ， Research, Law-to-Layer Weapon Law Page 508 735 Page 22