TW478066B - Method to remove precipitation for tungsten plug manufacture process - Google Patents

Abstract

This invention provides a manufacture method of tungsten plug for integrated circuit. The traditional manufacture method of tungsten plug is to from a contact hole or via hole, deposit a thick layer of tungsten and carry out anisotropic etch back on the tungsten layer using plasma etch technique to form tungsten plug in the contact hole or via hole. However, because the tungsten layer is very thick, long etch back time is required. The surface of tungsten layer at the center of the contact hole or via hole will gradually have dimple during the long etch back process. As the etch back process finishes, tungsten in the contact hole or via hole is etched away greatly and thus the resulted tungsten plug is not complete or flat. The method of the present invention describes a method to eliminate surface dimple of tungsten by depositing a very thin tungsten layer.

Description

478066 Printed B7 by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs 5. Description of the Invention (/) (1) Technical Field: The present invention is a method for removing deposits in the tungsten plug column process of Patent Application No. 84113808, with one additional, The present invention additionally discloses a manufacturing method for a tungsten plug (Integrated Circuit; 1C), which eliminates the phenomenon of dimple on the surface of tungsten metal. (II) Background of the Invention: The mother case relates to a method for removing Shen Dianwu from a tungsten stud process. The traditional method of manufacturing integrated circuits is to form a field oxide layer (Field 0xide) required to isolate the active area on the semiconductor substrate, and then form a Field Effect Transistor *; FET. [Field Effect Transistor] includes a gate dielectric layer (Gate

Dielectric), Gate electrode, Spacer and Source / Drain. After the field effect transistor is formed, [contact window] and [via] are formed, and then the metal interconnection process is performed. The currently widely used metal connection technology is the double-layer metal connection process (Double Level Metal Interconnection), where the First Level Metal Interconnection crosses the source / :: and pole (source /) of the [Contact Window] and Field Effect Transistor (-FET) Drain) is used for electrical contact, and the second-level metal connection (Second Level Metal Interconnection) makes electrical contact with the first-level metal connection across the [via] and the [攘 contact There are tungsten studs in the window and the interstitial hole. This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) ---------------- (Please read the precautions on the back before filling this page)

I I n I Order --------- 478066 A7 明 Description (d) The process method of the [first layer metal connection] described in the traditional [double layer metal connection] integrated circuit manufacturing process is as follows. First, an insulating layer 4 is formed on the semiconductor substrate 2, and then a lithography and plasma etching technology (Lithography & Plasma Etching) is used to form a contact window 5 (c〇ntact

Hole), and then forming a barrier metal layer 6 (Titanium; Ti) and titanium nitride (Nitride Titanium; TiN) based on Tibetan ore technology, wherein the titanium metal is located below the titanium nitride, said The barrier metal layer 6 crosses the [contact window 5], and then, a thick tungsten metal 8 is deposited, and the [thick tungsten metal 8] crosses and fills the [contact window 5], As shown in FIG. 1, then, the tungsten metal 8 is subjected to unidirectional etchback (anisotropic Etchback) by using a plasma etching technique, and the [unidirectional etchback] ends at the nitrogen The surface of titanium was changed to form a tungsten plug 10 (Tungsten Plug) in the [contact window 5]. As shown in FIG. 2, after completing the tungsten plug 10, a layer of silicon was sputtered. Copper alloy (Aluminum / Silicon / Coppei * Alloy), and the lithography technology plasma etching technology is used to etch away the aluminum-silicon-copper alloy, titanium and titanium nitride, and the [first layer metal connection] is completed in 焉. However, because the thickness of the tungsten metal is quite thick, it takes a long time to etch back, and in the long time etch back process, the surface of the tungsten metal at the center of the contact surface will gradually dimple, wait until ~ At the end of the etch back, the surface of the [tungsten plug 10] in the [contact window 5] has a concave P13 (Dimple), as shown in Figure 2. Therefore, when entering the field of sub-micron technology, find a method that can eliminate the dimple of tungsten metal surface to apply to the multi-layer metal connection process (MuW Levd. This paper applies the Chinese National Standard (CNS) A4 specification (210 χ 297) (Mm) (Please read the notes on the back before filling out this page) ▼ Install -------- Order ---------· #

Mem: mtercónzaki-is an important subject. The traditional [double-layer metal connection] of the known technology is the integrated electric process (random case (special financial application number, then)). ^ After the neodymium engraving, it can remove the precipitate formed on the surface containing titanium. Clothing, method. By strong oxidation, Laiguan joints undergo a chemical reaction to form a product that is exposed to water, which can be a precipitate on the metallographic side. (3) Brief description of the invention: The main objective of the present invention is to provide a method for removing sediments from the process of crane plugs-a method to eliminate depressions on the metal surface of the crane (_㈣, especially to eliminate [contact windows or media [Layer hole] method of [cracking the surface of a crane bolt]. The main manufacturing method of this additional invention is as follows. First, an insulating layer is formed on a semiconductor substrate, and then a [contact window] is formed by using lithography technology and plasma etching technology. C〇ntact H〇⑹, and then formed a barrier metal layer (Titanium; Ti) and titanium nitride (Nitride Titanium; TiN) barrier metal layer (Barrier Metal) by sputtering technology, titanium metal is located below the titanium nitride The barrier metal layer crosses the [contact window]; then, a thin layer of tungsten metal is deposited, and the [thin tungsten metal] crosses over and fills the [contact window], and then Using a plasma etching technique to perform unidirectional etchback on the [thin tungsten metal], and the [unidirectional etchback] ends on the surface of the titanium nitride to Tungsten plug (TungStenPlug). As the paper size of the tungsten metal is applicable to Chinese National Standard (CNS) A4 (210 X 297 mm) (Please read the precautions on the back before filling out this page) ▼ 装 * n -I n · ϋ US n · 订 Order ---------· # Intellectual Property Bureau of the Ministry of Economy Employees Cooperatives Printed Clothes 478066

Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs

'Installation -------- Order ---------% · (Please read the precautions on the back before filling in this page) The thickness is quite thin, so' You can complete the return in a short time, The tungsten metal surface at the center of the [contact window] will not cause a dimple ('Dimple') to form a complete and flat tungsten plug in the [contact window]. This is the inclination of the present invention. After the completion of the dimple-free pillar, a layer of Alrnnimim / Silieon / Copper alloy was then forged using the traditional standard process '' and the lithography and plasma etching techniques were used to etch away the aluminum-silicon-copper alloy and titanium [First layer metal connection] with titanium nitride was completed in 焉. (4) Brief description of the diagrams: Figures 1 to 2 are cross-sectional schematic diagrams of the process of forming tungsten studs by traditional methods. It is not intended that the cross section of the process of forming a button by the method of the present invention is shown in the figure. Figure 1 is a schematic cross-sectional view of the process after forming a [contact window] and depositing a [barrier metal layer] and [thick tungsten metal]; Plasma etching technology performs unidirectional etchback on the [thin tungsten metal] to form a cross-sectional schematic diagram of the process after a tungsten plug is formed in the [contact window]. Column] There is a dimple on the surface of the tungsten metal in the center; Figure 3 is a layer of Boro-Phosphate-TfetraEthylOrthoSilicate (· BPTEOS) and Planarized Monoxide Shi Xi]. Schematic diagram of the other aspects of the process after the contact window (c0ntactHole) is formed; Figure 4 is a layer of [barrier metal layer] and [thin tungsten]. The paper dimensions are in accordance with Chinese National Standard (CNS) A4 specifications ( (210 X 297 mm) 478066 A7 V. Schematic cross-sectional view of the process after the description of the invention (I) Metal], the [thin tungsten metal] crosses and fills the [contact window]; Figure 5 is the use of Plasma etching technology performs unidirectional etch-back on the [thin tungsten metal] to form a complete and flat [tungsten bolt] in the [contact window]; FIG. 6 This is a schematic cross-sectional view of the process after removing the [barrier metal layer] on the [Boron Phosphorous Silicon Dioxide] surface. (Please read the precautions on the back before filling this page) (5) Detailed description of the invention: The method of the present invention will be described below with the formation of the [first layer metal connection] as an example, but the method of the present invention can be widely applied to the second layer metal connection (Second Level Metal Connection). Inter connection) above metal structure. First, a [metal oxide half field effect transistor] (MOSFET) is fabricated on a silicon semiconductor substrate using a standard process, and the [metal oxide half field effect transistor] includes a gate dielectric. Gate (Gate Dielectric), gate electrode (Gate electrode), side wall (Spacer) and source / drain (Source / Drain) and other components, these components are not shown inadvertently. — Next, a layer of Boro-Phospho TetraEthylOrthoSilicate (BPTEOS) is deposited on the dream semiconductor substrate 20. [Miscellaneous Dioxide Stone 22] is usually formed by chemical vapor deposition (CVD), and its reaction pressure is about 760mtorr. This paper is in accordance with China National Standard (CNS) A4 (210 χ). 297 public love) Order -------- 478066

Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs

The thickness is between 5 Å and 1 G Angstrom. After the deposition is completed, the [Boron Phosphorous Silicon Dioxide 22] is planarized with a thermal flow rectification technique (Flow). Then, the lithography technology plasma etching technology is used to etch away the [borophosphorus silicon dioxide 22] to form a contact window 23 (contactHole). As shown in FIG. 4, in the future, the metal connection will pass through the [contact window 23] ] Make electrical contact with the source / non-electrode area of the [Gold Oxygen Half Field Effect Transistor]. Next, a barrier metal layer 24 (titanium; Ti) and titanium nitride (Nitride Titanium; TiN) is formed by sputtering, and the titanium metal is located below the titanium nitride. [Barrier metal layer 24] Crosses the contact window 23, wherein the thickness of titanium is about 300 angstroms, and the thickness of titanium nitride is about 15,000 angstroms. Next, a thin layer of tungsten metal 26 is deposited, and the [thin tungsten metal 26] crosses and fills the contact window 23, as shown in FIG. The "thick metal 26" is generally formed by reacting tungsten hexafluoride gas (WF6) by chemical vapor deposition (CVD), and the thickness is between 2000 and 3000 angstroms. In the meantime, this is a key step of the present invention, because when the tungsten plug is formed by the conventional method, the thickness of the tungsten metal is between 6000 and 8000 angstroms, and the thickness is very thick (as shown in Fig. 1). Then, using a plasma etching technique, the [thin-thick tungsten metal-24] is subjected to unidirectional etchback, and the [unidirectional etchback] ends on the surface of the [barrier metal layer 22]. To form a tungsten plug 28 (TungstenPlug) in the [contact window 23], as shown in FIG. Because the thickness of the tungsten metal 26 is quite thin, the paper can be completed in time. ^ Applicable to China National Standard (CNS) A4 specifications (21〇X 297 public love) (Please read the note on the back? Matters before filling (This page) 478066 A7

V. Description of the invention (^) For the rest of the time, the crane gold in the center of the [contact window 23] will not cause a dimple, and can be flat and flat in the [contact window 23]. Tungsten plug 28], as shown in Figure 5, this is the key step. Next, remove the [barrier metal layer 24] of [Boron Phosphorous Silicon Dioxide], as shown in FIG. At the end of the surface, the thin film sputtering of Almnmum / Silicon / Copper Alloy is carried out by the traditional standard process, and the two-barrier technology and plasma etching technology are used to remove the [barrier metal layer 24] and [Second / Shi Xi / Copper Metal Alloy], completed with no depression [Tungsten Bolt called [First Layer Metal Connection]]. The above is based on the best practices of the present invention, and those who are familiar with semiconductor technology can understand that slight changes and adjustments will still not lose the essence of the invention, nor depart from the spirit and scope of the invention. . Printed by the Consumer Cooperatives of the Intellectual Property Bureau of the Ministry of Economic Affairs 8

Claims (1)

Sixth, the scope of patent application • The method for removing deposits in the tungsten stud process includes an additional method, which includes: forming a layer of insulation on a semiconductor substrate; forming a [hole] (hole), the [hole] Between the conductors; forming a barrier metal layer (the barrier metal layer) across the [holes]; forming a thin layer of the Tungsten metal, the [thickness is very Thin tungsten metal] straddles and fills the "holes"; Anisotropic Etchback is performed on the [thinly thin tungsten metal] using etching technology, and the [unidirectional Carved back to the last name] Terminated on the surface of the [barrier metal layer] to form a crane laurel: column (Tungsten Plug) in the [hole]; etch back the [barrier metal layer] using an etching technique (Etchback) The etch-back ends at the [insulating layer]. 2. According to the method for removing deposits in the tungsten plug process of item 1 of the scope of the patent application, an additional method is added, in which the [semiconductor substrate] contains [transistor], [resistor], [inductor], and [capacitor] And other electronic components. Printed by the Consumer Cooperative of the Intellectual Property Bureau of the Ministry of Economic Affairs. 3. If the method for removing deposits in the tungsten stud process of the patent application item No. 丨 is added, the [barrier metal layer] contains at least a conductive layer (Conductor). Layer) ° 4. According to the method for removing deposits in the tungsten plug process of item 1 of the scope of patent application, an additional one is described, in which the thickness of the [thin tungsten metal] is between 2000 and 4000 angstroms. between. , 9