TW554423B - Tungsten gate structure and method for producing the same - Google Patents

Abstract

The present invention relates to a tungsten (W) gate structure and a method for producing the same which can prevent the oxidation of W in a metal gate. The structure comprises: a gate oxide layer located on the surface of a semiconductor substrate; a polysilicon layer located on the gate oxide layer; a diffusion barrier layer located on the polysilicon layer; a W metal layer located on the diffusion barrier layer; an oxygen barrier layer located on the W metal layer; and an insulative layer located on the oxygen barrier layer. The structure further comprises an insulative sidewall on the two sides of the W gate, a source/drain region, and a lightly doped source/drain region, thereby forming a complete W gate structure.

Description

554423 V. Description of the Invention (1) [Field of the Invention] The present invention relates to semiconductor process technology, and more particularly to a tungsten metal gate structure and manufacturing method, which can prevent the tungsten metal in the metal gate from oxidizing to provide good Metal gate quality. [Background of the Invention] Semiconductors § Memory devices can be divided into read-write memory and read-only memory (read on 1 y), and read-write memory can be divided into DRAM And SRAM. At present, DRAM is the main application of § memory device, which is composed of a capacitor (capaCitor) and a transistor (transistor). Due to the rapid research on memory, the memory capacity is increasing four times every three years. For example, the current 2 56 Mb DRAM, and larger DRAM such as 1 Gb DRAM have also been used by various business and academic circles. Widely researched. To this end, doped poly-si iicQn materials have been widely used in gate electrodes of semiconductor devices, and a tungsten Si 1 pesticide can be deposited to reduce the resistance value of the gate electrodes. . The resistance value of Shixihua tungsten thin film is about 100mm. The resistance value is still too high for DRA M above 1 Gb with larger memory capacity and finer gate line width. There is a need for metal gate materials that can provide lower resistance values, such as Tungsten (W) metal, which has a resistance value of about 10 cm, and many related studies have appeared in recent years. Disclosed in US Patent No. 6,340,62, a tungsten metal gate structure

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Therefore, ‘tungsten metal is exempted: the metal is diffused to the polycrystalline silicon material below it, and its material is nitrogen 2: it forms a diffusion barrier layer on the polycrystalline stone layer. Tungsten (WN) is used to form tungsten metal on the above diffusion barrier layer. After the formation of the crane metal layer, the remaining etching material is usually silicon nitride, and its shape (LP-furnace) is usually more formed. Cap layer (etching mask), the forming method is usually high temperature and low pressure furnace control process

However, the use of tungsten metal as the gate material still has its shortcomings. It is disclosed in U.S. Patent No. 6,346,467.

In the process, under high temperature (approximately 900 ° C and oxygen-containing furnace control process, tungsten metal oxidation will occur. Although the furnace tube machine has been equipped with a load lock and related The nitrogen shower box (N2 shower b0x) uses nitrogen to reduce the oxygen concentration (02 density) inside the furnace tube before the wafer enters the furnace tube, but in the presence of a trace amount of oxygen (<100 ppm), This undesired tungsten metal oxidation situation will still be caused. After the subsequent formation of silicon nitride material, the testing machine (such as KLA inspection) detects the nitrided surface of the wafer caused by the tungsten oxide oxidation. Embedded defects under the silicon layer. This defect is not a micro-floating particle but is caused by the oxidation of tungsten metal, which not only affects the quality of the tungsten gate material itself, but also causes silicon silicon. The surface uniformity of the layer is not uniform. After the subsequent etching process is completed, the more severe ones may find the connection between the two word lines formed by the etching residue, and the word line to word line disconnection is found in the subsequent electrical test. line to word line sh〇rt), for metal

〇548-8242TWF (N)-91010 · Shawn.ptd Page 5 554423 5. Description of the invention (3) The interpolar process has a serious impact. [Summary of the Invention] In view of this, the present invention is a kind of metal gate temperature furnace that generates oxygen during the control process in order to achieve the above-mentioned purpose. . In short, the present invention includes: forming a thin oxygen polycrystalline silicon layer on the thin oxide layer, depositing a metal barrier layer on the tungsten metal layer to oxidize by contacting oxygen atoms; Shen defines the insulating layer, the The tungsten metal gate structure of the first layer, the far-secondary crystal layer, and the layer is due to the fabrication of the present invention and subsequent defects caused by the oxidation of the high-temperature furnace tube metal. The main purpose is to provide protection against gate gold. The King of Spears can prevent the gate metal from increasing in the future. The present invention provides a new tungsten metal gate junction structure. In the process of high-temperature furnace control of titanium gold in a titanium nitride / titanium composite layer, the oxidation of the tungsten metal gate is stopped by diffusion of titanium oxide. In order to maintain its junction, a tungsten metal gate structure and a manufacturing method, a stepped layer is deposited on the surface of a half-conductor substrate; a layer is deposited, and a first barrier layer is deposited on the polycrystalline silicon layer on the second barrier Layer; depositing a second barrier to prevent the tungsten metal layer from accumulating an insulating layer on the second barrier layer in the subsequent thermal process; and two barrier layers, the metal layer, and the first barrier layer Oxidation layer to form an insulating cap can greatly improve the quality of the tungsten metal gate. After the manufacturing process, it can prevent the occurrence of embedded defects in the metal gate structure under the insulating cap layer. Improve Product Yield, Improve »

554423 5. Description of the invention (4) Product reliability. [Embodiment] The embodiment of the present invention will be described in detail with reference to Figs. 1 to 3 as follows. As shown in Fig. 1, Baixian is a semiconductor substrate, such as a silicon substrate. A thin oxide layer 2 and a polycrystalline silicon layer 14 are sequentially formed. The thin and thin layer 12 is used as the gate oxide layer. It is usually formed slowly by dry or wet thermal oxidation at 700 ~ 1000, and the thickness is about 30 ~ 100 angstroms. The polycrystalline silicon layer 14 is a doped polycrystalline silicon layer. Taking the formation of NMOS as an example, doped phosphine can be performed in-situ by plasma chemical vapor deposition (PECVD). (Phosphine) or arsine gas ('arsine') gas to form a polycrystalline silicon layer having a thickness of about 10 ⑽ to 200 (}) angstroms. Next, 'physical vapor deposition (pvD) was performed on the polycrystalline silicon A diffusion barrier layer 15 is deposited on layer 14 and is made of tungsten nitride (WN) and has a thickness between 30 and 100 angstroms to form a diffusion barrier between a tungsten metal and a polycrystalline silicon layer. After the diffusion barrier layer 15 is deposited, next, a crane metal layer 16 is deposited on the diffusion barrier layer 15 by a physical vapor deposition method (pvD) as the material of the gate portion of the metal gate. , Its thickness is between 200 and 100 angstroms. Then a physical vapor deposition (pVD) method is used to deposit a titanium metal (Ti) layer with a thickness of about 50 angstroms to 300 angstroms. situ) nitride the titanium metal layer to form a titanium nitride / titanium composite layer composed of titanium nitride 18b and titanium metal 18a, wherein the thickness ratio of titanium nitride / titanium is between 3: 1 ~ 1: 1, nitrogen Turn into / Fu composite layer (TiN / Ti) 18b / 18a visual oxygen barrier (ο X y g e n b a r r i e r) layer, using for this purpose the composite layer of the metal gate structure

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V. Description of the invention (5) Titanium nitride 18b acts as a diffusion barrier (dif fusión baRier) layer for oxygen molecules, and utilizes the characteristic that titanium is more easily oxidized with oxygen molecules than tungsten, so that diffusion through the nitride layer 18a Before the oxygen molecules are in contact with the tungsten metal layer 16, they are in contact with the titanium metal 18 a and are oxidized to ensure that the tungsten metal is not in contact with the oxygen, and the oxidation effect of the tungsten metal will not occur. Next, an insulating layer 20 is deposited, which will be used as a gate cap insulating layer in the future. The method is to use a low pressure chemical vapor deposition method (LPCVD) to deposit a thickness between 500 and 900 ° C. The nitrided fragmented layer is between 2000 and 2000. Next, using conventional lithography imaging and reactive ion etching techniques such as CHF3, C12 and other etching sources, the above layers are defined as the gate structure shown in Figure 2. After the second etching is completed, an oxygen plasma can be used to dry the electrode. The photoresist process and the wet cleaning process remove the photoresist, and the thin oxide layer not covered by the gate structure can be removed through the wet cleaning process. As &amp; obtained-a tungsten metal gate structure G with an insulating cap layer 20, which has an ideal gate tungsten metal quality 0

Please refer to Figure 3. After that, according to the traditional process technology, a lightly doped source / drain region (LDD) 24 can be fabricated by ion implantation and rapid thermal tempering procedures, and then chemical vapor deposition and tempering can be performed. The insulating sidewall layer 22 is formed by an etching process, and a source / drain region 2 6 ′ is formed by ion implantation and rapid thermal tempering to complete the fabrication of a tungsten metal gate. The structure of the metal gate of the present invention, as shown in FIG. 3, includes: a gate oxide layer on a semiconductor substrate surface; a polycrystalline silicon layer on the gate oxide layer; a diffusion barrier layer On the polycrystalline silicon layer;

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The crane metal layer is located on the diffusion barrier layer and the oxygen barrier layer is located on the tungsten metal layer; and the _insulation layer is located on Yeli .....- the insulation located on both sides of the town's metal interrogator; 2 On the layer, a lightly doped source / drain region is further formed to form a complete technical memo / dead region, and although the present invention has been described with a preferred embodiment, a black metal gate structure. Limit the date and time of this issue. Anyone who is familiar with this skill is not used within the scope. It can be used for various changes and retouching. The scope of the spirit is based on the scope of the attached patents = the protection of the present invention.

0548-8242TWF (N); 91010: Shawn.ptd $ 9, page 554423 Brief description of the diagram Figure 3 is a series of cross-sectional views, which are used to illustrate the fabrication of a polycrystalline silicon metal gate tungsten metal gate Pole structure and manufacturing method. Explanation of symbols] 10 ~ semiconductor substrate; 1 ~ 4 ~ polycrystalline silicon layer; 16 ~ ferrous metal layer; 18b ~ titanium nitride layer; 2 ~ 2 insulating sidewall; 26 ~ source / drain region 1 ~ 2 thin oxide layer 15 ~ diffusion barrier layer; 18a ~ titanium metal layer; 20 ~ insulating layer; 24 ~ lightly doped source / drain region G ~ gate structure.

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Claims (1)

Six patent application scopes ______ 1 · 4 kinds of black metal alloys, including the following steps y ° manufacturing method, can prevent the gate tungsten metal oxygen to form a gate oxide layer deposited a polycrystalline silicon layer on the surface of a semiconductor substrate Depositing a tungsten metal: on a thin oxide layer; to prevent the tungsten metal layer from depositing an oxygen barrier ^ = the polycrystalline silicon layer contacts the insulating metal layer in the subsequent thermal process to define the insulating layer, ΐ! On the barrier layer; and the layer, and the inter-electrode oxide layer: =: bean; oxygen barrier layer, the polycrystalline stone gate structure. A method for forming a tungsten metal with an insulating cap layer is as follows: Step 2: forming the tungsten metal gate described in item 1 above to form a diffusion barrier layer on the polycrystalline stone layer. The bracketing method, 3jl ::, manufacturing method of tungsten metal gate described in the first item of the scope /, the gate oxide layer is formed by a thermal oxidation method. 4 In the manufacturing method of tungsten metal gate described in item 丨 of the scope of Shenyan's patent, the polycrystalline silicon layer is formed by plasma chemical vapor deposition (pECVD). | 5 · If the scope of patent application is the first The method for manufacturing a tungsten metal gate according to the above item 'wherein the polycrystalline silicon layer is a doped (i) doped compound silicon layer. 6 · The manufacturing of the tungsten metal gate according to item 2 of the scope of patent application Method 'wherein the material of the diffusion barrier layer is a tungsten nitride layer. 7 · The manufacturer of the tungsten metal gate described in item 6 of the scope of patent application 554423 VI. Patent Application Method ′ The tungsten nitride layer is formed by physical fluorine phase deposition (PVD). 8. The method for manufacturing a tungsten metal gate according to item 1 of the scope of patent application, wherein the material of the oxygen barrier layer is a composite layer composed of titanium nitride / titanium. 9 · The method for manufacturing a tungsten metal gate as described in item 8 of the scope of the patent application, wherein the method for forming the oxygen barrier layer is a physical vapor deposition (PVD) method in which a titanium metal layer is deposited and in-situ (in- situ) nitride the titanium metal layer to form a titanium nitride / titanium composite layer. I 〇. The method for manufacturing a tungsten metal gate as described in item 8 of the scope of the patent application, wherein the titanium nitride / titanium composite layer has a thickness ratio of titanium nitride to titanium ranging from 3: 1 to 1: 〇II · The method for manufacturing a tungsten metal gate as described in item 1 of the scope of the patent application, wherein the insulating layer is made of silicon nitride. 1 2 · The manufacturing method of tungsten metal gate structure as described in item 1 of the scope of patent application, wherein a metal gate structure with an insulating cap layer is formed 2 Anisotropic etching is performed using a reactive ion etching process . 1 3 · A method for manufacturing a tungsten metal gate to prevent oxidation of the gate tungsten metal, including the following steps: forming a thin oxide layer on the surface of a semiconductor substrate; depositing a polycrystalline silicon layer on the thin oxide layer; Depositing a diffusion barrier layer on the polycrystalline silicon layer; depositing a tungsten metal layer on the diffusion barrier layer; depositing a titanium nitride / titanium composite layer on the crane metal layer; depositing an insulating layer on the nitrogen Titanium / titanium composite layer; and defining the insulating layer, the vaporized titanium / titanium composite layer, the crane metal layer, 〇548-8242TWF (N) * 91010; Shawn.ptd Page 12 554423 And the thin oxide layer μ wind, the diffusion barrier layer, the polycrystalline silicon layer _ a tungsten metal gate structure with an insulating cap layer. Fang, 4, · Shi Shen called the manufacture of tungsten metal gate described in item 13 of the patent scope, and / or the thin oxide layer was formed by a thermal oxidation method. Fifteen: The manufacturing of tungsten metal gate as described in item 13 of the scope of the patent application &amp; 1, wherein the polycrystalline silicon layer is formed by plasma chemical vapor deposition (PECVD). 16. The method for manufacturing a tungsten metal gate as described in item 13 of the scope of the patent application, wherein the polycrystalline silicon layer is a doped polycrystalline silicon layer. 17. The method for manufacturing a tungsten metal gate as described in item 13 of the scope of the patent application, wherein the material of the diffusion barrier layer is tungsten nitride (WN). 1 8. The method for manufacturing a tungsten metal gate as described in item 17 of the scope of the patent application, wherein the method for forming the diffusion barrier layer uses a physical vapor deposition method (PVD). 19 · The method for manufacturing a tungsten metal gate as described in item 13 of the scope of the patent application, wherein the titanium nitride / titanium composite layer is formed by using a physical vapor deposition (PVD) method to plate a titanium metal. Layer on the crane metal layer, and nitride the titanium metal layer into a titanium nitride / titanium composite layer in-situ. 2 0. The method for manufacturing a tungsten metal gate as described in item 13 of the scope of the patent application, wherein the thickness ratio of the titanium nitride / titanium is between 3: 1 to 1: 1. 2 1 · The method for manufacturing a tungsten metal gate according to item 13 of the scope of the patent application, wherein the thickness of the titanium nitride / titanium composite layer is between 50 and 300 angstroms. 2 2 · The method for manufacturing a tungsten metal gate as described in item 13 of the scope of patent application, wherein the insulating layer is silicon nitride. 〇548-8242TWF (N) * 91010; Shawn.ptd Page 13 554423 554423 0548-8242TWF (N); 91010; Shawn.ptd page 15