阅读说明：本技术 在半导体晶片上制作半导体结构的方法 (Method for fabricating semiconductor structure on semiconductor wafer ) 是由 张峰溢 李甫哲 陈界得 徐庆斌 于 2018-07-10 设计创作，主要内容包括：本发明公开一种在半导体晶片上制作半导体结构的方法。首先提供一半导体晶片,具有一第一区域、一第二区域和一晶边区域。在第一区域和第二区域内分别形成一第一半导体结构和一第二半导体结构。接着对半导体晶片进行一晶边等离子体处理制作工艺,仅仅在晶边区域内形成一阻挡层。再进行一硅化金属制作工艺,在第一区域和第二区域内形成一硅化金属层。(The invention discloses a method for manufacturing a semiconductor structure on a semiconductor wafer. First, a semiconductor chip having a first region, a second region and a chip edge region is provided. A first semiconductor structure and a second semiconductor structure are formed in the first region and the second region, respectively. Then, a wafer edge plasma processing manufacturing process is carried out on the semiconductor wafer, and a barrier layer is formed only in the wafer edge area. And performing a metal silicide manufacturing process to form a metal silicide layer in the first region and the second region.)

1. A method of fabricating a semiconductor structure on a semiconductor wafer, comprising:

providing a semiconductor wafer, wherein the semiconductor wafer is provided with a first area, a second area and a wafer edge area;

forming a first semiconductor structure and a second semiconductor structure in the first region and the second region, respectively;

carrying out a crystal edge plasma processing manufacturing process on the semiconductor wafer, and forming a barrier layer only in the crystal edge region; and

and performing a metal silicide manufacturing process to form metal silicide layers in the first region and the second region.

2. The method of claim 1, wherein the first area is a memory area and the second area is a periphery circuit area.

3. The method of claim 2, wherein the first semiconductor structure comprises a storage node contact structure of a memory cell and the second semiconductor structure comprises a source or drain contact structure of a transistor.

4. The method of claim 2, wherein the barrier layer is a silicon dioxide layer.

5. The method of claim 1, wherein the silicon dioxide layer is formed by oxidizing a silicon surface of the edge region during the edge plasma processing fabrication process.

6. The method of claim 1, wherein during the edge plasma processing, the semiconductor wafer is placed in an edge etcher that is configured with a Plasma Exclusion Zone (PEZ) ring.

7. The method of claim 1, wherein the barrier layer comprises silicon oxynitride, silicon oxycarbide, silicon nitride, or silicon carbide.

8. The method of claim 1, wherein said metal silicide fabrication process comprises:

forming a metal film on the barrier layer in the first region and the second region and the edge region;

performing a thermal process to form the silicide layer only in the first region and the second region; and

removing the unreacted metal film from the barrier layer in the first region, the second region and the edge region.

9. The method of claim 1, wherein the metal silicide layer comprises cobalt silicide or nickel silicide.

10. The method of claim 1, wherein after completing said metal silicide fabrication process to form said metal silicide layer in said first region and said second region, said method further comprises:

depositing a conductive layer only in the first region and the second region; and

patterning the conductive layer to form a storage node pad in the first region and a contact plug and a M in the second region₀A metal layer, and a silicon surface is exposed in the edge region.

Technical Field

The present invention relates to the field of semiconductor manufacturing technology, and more particularly, to a method for fabricating a semiconductor structure, such as a storage node contact structure and/or a contact plug, on a semiconductor wafer.

Background

In semiconductor fabrication processes, particularly in the former stage, it is often necessary to perform a so-called metal silicide (silicidation) process to reduce contact resistance by forming a metal silicide layer on a silicon surface.

However, in the conventional manufacturing method, a silicide layer is formed on the edge region of the silicon wafer, and the silicide layer formed on the edge region or by-products generated in the subsequent etching process are likely to be peeled off in the reaction chamber of an etching machine (e.g., an etching machine for etching tungsten metal), which causes a contamination problem of the etching machine and affects the reliability or yield of the manufacturing process.

Accordingly, there is still a need in the art for an improved method for overcoming the above-mentioned deficiencies and drawbacks of the prior art.

Disclosure of Invention

The present invention is directed to an improved method for fabricating a semiconductor structure on a semiconductor wafer, which can prevent a silicide layer from being formed on a wafer edge region of the silicon wafer during a silicide fabrication process, thereby solving the problem of contamination of an etching machine and improving the reliability or yield of the fabrication process.

According to one embodiment of the present invention, a method of fabricating a semiconductor structure on a semiconductor substrate is provided. First, a semiconductor chip having a first region, a second region and a chip edge region is provided. A first semiconductor structure and a second semiconductor structure are formed in the first region and the second region, respectively. Then, a wafer edge plasma processing manufacturing process is carried out on the semiconductor wafer, and a barrier layer is formed only in the wafer edge area. And performing a metal silicide manufacturing process to form a metal silicide layer in the first region and the second region. For example, the barrier layer may be a silicon dioxide layer.

The first region may be a memory region, and the second region may be a peripheral circuit region. The first semiconductor structure includes a storage node contact structure of a memory cell, and the second semiconductor structure includes a source or drain contact structure of a transistor.

According to the invention, before the silicide manufacturing process is carried out, the barrier layer is only formed in the edge region BR of the semiconductor wafer by the edge plasma processing manufacturing process, so that a silicide layer is prevented from being formed in the edge region BR in the silicide manufacturing process, therefore, the pollution problem of an etching machine can be solved, and the reliability or yield of the manufacturing process is improved.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below. However, the following preferred embodiments and the accompanying drawings are only for reference and illustration purposes and are not intended to limit the present invention.

Drawings

FIG. 1 is a top view of a semiconductor wafer;

FIG. 2 is a schematic cross-sectional view of the semiconductor wafer of FIG. 1;

FIGS. 3-9 are schematic cross-sectional views illustrating a method of fabricating a semiconductor structure on a semiconductor wafer according to one embodiment of the invention;

fig. 10 is a schematic diagram of a wafer edge plasma processing process performed on a semiconductor wafer.

Description of the main elements

10 first semiconductor structure

11 bit line structure

20 second semiconductor structure

21 transistor

100 semiconductor wafer

101 semiconductor substrate

101a silicon surface

102 element isolation region

111 polysilicon layer

112 tungsten metal layer

113 upper cover layer

121 source or drain region

210 gate structure

211 polycrystalline silicon layer

212 tungsten metal layer

213 Top cover layer

214 spacer

215 contact etch stop layer

300 dielectric layer

310 storage node contact hole

311 storage node contact structure

320 source or drain contact structure

410 barrier layer

412 metal film

420 silicide metal layer

426 conductive layer

430 pattern transfer stack layer

431 silicon nitride layer

432 organic dielectric layer

433 silicon-containing hard mask bottom anti-reflective coating layer

440 photoresist pattern

440a opening

500 crystal edge etching machine

510 upper metal piece

510a gas line

511 PEZ Ring

512 upper electrode

520 chip seat

Lower PEZ Ring 521

522 lower electrode

550 reaction chamber

Central region of CR

First region of CR-1

Second region of CR-2

BR crystal edge region

SC storage node pad

CP contact plug

M₀Metal layer

Detailed Description

In the following, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the embodiments may be practiced. The following examples are described in sufficient detail to enable those skilled in the art to practice them.

Of course, other embodiments may be utilized and structural, logical, and electrical changes may be made without departing from the embodiments described herein. The following detailed description is, therefore, not to be taken in a limiting sense, and the embodiments included therein are defined by the appended claims.

Referring to fig. 1 and fig. 2, fig. 1 is a top view of a semiconductor wafer, and fig. 2 is a cross-sectional view of the semiconductor wafer of fig. 1. As shown in fig. 1 and 2, the semiconductor wafer 100 has a disc-shaped structure, and has a central region CR and a wafer level region BR surrounding the central region CR. Taking a 12-inch silicon wafer as an example, the edge region BR refers to an annular band-shaped region having a width of about 1 to 3 millimeters (mm), for example, 2 mm, along the edge of the semiconductor wafer 100. Semiconductor circuit elements, such as transistors or memory cells, are formed in the central region CR. In the edge region BR, a semiconductor structure such as a transistor or a memory cell is not usually formed.

Referring to fig. 3 to 9, cross-sectional views of a method for fabricating a semiconductor structure on a semiconductor wafer according to an embodiment of the invention are shown, wherein the same reference numerals are used for the same regions, elements and material layers. As shown in FIG. 3, a semiconductor wafer 100 is first provided, which includes a semiconductor substrate 101, such as a silicon substrate, having a first region CR-1, a second region CR-2 and a wafer edge region BR thereon. Wherein the first region CR-1 and the second region CR-2 are both located in the central region CR of FIGS. 1 and 2. for example, the first region CR-1 may be a memory region and the second region CR-2 may be a peripheral circuit region.

According to the embodiment of the invention, a plurality of memory cells or a memory cell array can be formed in the memory area, and a transistor structure of a peripheral circuit can be formed in the peripheral circuit area. For simplicity of illustration, only a single memory cell and a single transistor structure are shown.

As shown in fig. 3, a first semiconductor structure 10 and a second semiconductor structure 20 have been formed on the semiconductor substrate 101 in the first region CR-1 and the second region CR-2, respectively. According to an embodiment of the present invention, the first semiconductor structure 10 includes a storage node contact structure 311 of a memory cell. According to an embodiment of the present invention, the first semiconductor structure 10 includes a bit line structure 11 disposed in a dielectric layer 300 and extending into the semiconductor substrate 101.

A storage node contact hole 310 is formed in the dielectric layer 300 beside the bit line structure 11, and a storage node contact structure 311 is located at the bottom of the storage node contact hole 310 and contacts with a portion of the semiconductor substrate 101. The storage node contact structure 311 does not fill the storage node contact hole 310. In the semiconductor substrate 101, an element isolation region 102, such as a shallow trench isolation region, is further formed for isolating the elements. According to an embodiment of the present invention, the storage node contact structure 311 comprises an amorphous silicon (amorphous Si) or polysilicon. According to an embodiment of the present invention, the bit line structure 11 may include, but is not limited to, a polysilicon layer 111, a tungsten layer 112, and a capping layer 113.

According to an embodiment of the present invention, the second semiconductor structure 20 includes a source or drain contact structure 320, or contact hole, of a transistor 21, which exposes a portion of the source or drain region 121 in the semiconductor substrate 101. According to an embodiment of the present invention, the transistor 21 includes a gate structure 210, for example, formed by stacking a polysilicon layer 211, a tungsten metal layer 212, and a cap layer 213. A spacer 214 may be formed on the sidewalls of the gate structure 210 and a contact etch stop layer 215 may be formed over the transistor 21. A dielectric layer 300 is formed on the contact etch stop layer 215.

Since the bit line structure 11, the storage node contact structure 311, the gate structure 210, the source or drain region 121, the contact etch stop layer 215, the dielectric layer 320, and the source or drain contact structure 320 are well known in the art, the details thereof are not described herein. According to the embodiment of the invention, after the first semiconductor structure 10 and the second semiconductor structure 20 are formed on the semiconductor substrate 101 in the first region CR-1 and the second region CR-2, respectively, the silicon surface 101a of the semiconductor substrate 101 in the edge region BR is exposed.

As shown in fig. 4, an edge plasma process is then performed on the semiconductor wafer 100 to form a barrier layer 410 only in the edge region BR. According to an embodiment of the present invention, the barrier layer 410 is a silicon dioxide layer. The silicon dioxide layer is formed by oxidizing the silicon surface 101a of the edge region BR during the edge plasma treatment process and has a thickness of about 10a to 20 a, but is not limited thereto. The thickness of the barrier layer 410 is sufficient to resist the reaction of a subsequently deposited metal layer (e.g., cobalt or nickel) with the underlying silicon surface 101 a.

Referring now to FIG. 10, therein is shown a schematic view of a wafer edge plasma processing process performed on a semiconductor wafer. In performing the edge plasma processing process, the semiconductor wafer 100 is placed in an edge etcher 500 having a Plasma Exclusion Zone (PEZ) ring according to an embodiment of the present invention. As shown in fig. 10, the edge etcher 500 includes an upper PEZ ring 511 and a lower PEZ ring 521 near the edge region BR of the semiconductor wafer 100. The semiconductor wafer 100 is placed on a wafer pedestal 520, for example, the wafer pedestal 520 may be a vacuum chuck (vacuum chuck) or an electrostatic chuck (E-chuck).

According to the embodiment of the present invention, the upper PEZ ring 511 may be disposed around an upper metal 510 such that the upper metal 510 is flush with the lower surface of the upper PEZ ring 511 and maintains a predetermined distance from the semiconductor wafer 100. The upper metal 510 may be made of aluminum metal, and the surface thereof may be anodized. A gas line 510a may be provided inside the upper metal member 510 for supplying a predetermined gas to control the diffusion of the plasma gas. An upper electrode 512 may be disposed outside the upper PEZ ring 511, and a lower electrode 522 may be disposed outside the lower PEZ ring 521 to provide an electric field of a predetermined power sufficient to generate plasma in the reaction chamber 550 and diffuse into the edge region BR.

According to the embodiment of the present invention, the wafer edge plasma processing process may utilize oxygen plasma, and the gas supplied through the gas line 510a controls the diffusion of the plasma gas, and the oxygen plasma reacts with the wafer edge region BR of the semiconductor wafer 100 only to form a silicon dioxide barrier layer through the adjustment of the upper PEZ ring 511 and the lower PEZ ring 521. However, the invention is not limited to the example where the barrier layer 410 is a silicon dioxide layer, and in other embodiments, barrier layers 410 of different compositions may be obtained by adjusting the plasma gas composition (e.g., nitrogen, oxygen, carbon monoxide, carbon dioxide, etc.), for example, barrier layer 410 may comprise silicon oxynitride, silicon oxycarbide, silicon nitride, or silicon carbide.

As shown in fig. 5 and 6, a metal silicide process is then performed.

First, as shown in FIG. 5, a metal film 412, such as a cobalt or nickel layer, is formed on the barrier layer 410 in the first region CR-1 and the second region CR-2 and the edge region BR. The metal film 412 may be conformally deposited on the surface of the storage node contact hole 310, the surface of the storage node contact structure 311 and the bit line structure 11 in the first region CR-1 by a deposition method, such as an Atomic Layer Deposition (ALD) method, and the metal film 412 is conformally deposited on the surface of the source or drain contact structure 320 and the dielectric layer 300 in the second region CR-2.

Then, as shown in fig. 6, a thermal process, such as a Rapid Thermal Process (RTP), is performed to make the metal film 412 react with the surface of the storage node contact hole 310 and the silicon surface in the source or drain contact structure 320 to form a silicide layer 420, and the barrier layer 410 covers the silicon surface 101a of the edge region BR, so that the metal film 412 does not react with the silicon surface 101a of the edge region BR to form a silicide layer.

Next, the metal silicide layer 420 is formed only in the first region CR-1 and the second region CR-2 by removing the unreacted metal film 412 from the first region CR-1 and the second region CR-2 and removing the unreacted metal film 412 from the barrier layer 410 in the edge region BR by etching, for example, using a sulfuric acid solution. According to an embodiment of the present invention, the metal silicide layer 420 may include cobalt silicide or nickel silicide.

Next, as shown in fig. 7 to 9, after the silicide layer 420 is formed in the first region CR-1 and the second region CR-2 after the silicide formation process is completed, the formation of the storage node pads in the first region CR-1 and the formation of the contact plugs in the second region CR-2 are performed.

As shown in fig. 7, a conductive layer 426, for example, a tungsten metal layer, is selectively deposited only in the first region CR-1 and the second region CR-2. The conductive layer 426 fills the storage node contact hole 310 in the first region CR-1 and is in direct contact with the silicide layer 420, and the conductive layer 426 fills the source or drain contact structure 320 in the second region CR-2. The conductive layer 426 is not formed in the edge region BR, so that the barrier layer 410 in the edge region BR is exposed.

As shown in FIG. 8, a pattern transfer stack 430, for example, including, but not limited to, a silicon nitride layer 431, an Organic Dielectric Layer (ODL)432 and a silicon-containing hard mask bottom anti-reflective coating (SHB) layer 433, is then blanket deposited in the first region CR-1, the second region CR-2 and the edge region BR. Then, a photoresist pattern 440 is formed on the pattern transfer stack layer 430, including an opening 440a, exposing a portion of the surface of the pattern transfer stack layer 430.

As shown in FIG. 9, an anisotropic dry etching process is then performed to pattern the conductive layer 426, form the storage node pads SC in the first region CR-1 and form the contact plugs CP and M in the second region CR-2₀A metal layer, while the silicon surface 101a is exposed in the edge region BR. During the pattern transfer process, the silicon nitride layer 431 and the silicon-containing hard mask bottom anti-reflective coating (SHB) layer 433, which were originally formed in the edge region BR, are removed, thereby exposing the silicon surface 101 a.

In the invention, before the silicide manufacturing process is carried out, the barrier layer 410 is only formed in the edge region BR of the semiconductor wafer 100 by the edge plasma processing manufacturing process, so that the silicide layer is prevented from being formed in the edge region BR in the silicide manufacturing process, therefore, the pollution problem of an etching machine can be solved, and the reliability or the yield of the manufacturing process can be improved.

The above description is only a preferred embodiment of the present invention, and all equivalent changes and modifications made in the claims of the present invention should be covered by the present invention.