TWI885902B - Semiconductor device and method of making the same - Google Patents

Abstract

A method of making a semiconductor device includes: forming a semiconductor structure including a substrate, a dielectric bottom layer, a conductor layer, and a dielectric cap layer sequentially stacked; etching the semiconductor structure to form a trench, in which the trench penetrates the dielectric cap layer, the conductor layer, and the dielectric bottom layer and exposes a first portion of the substrate and a residual area of the dielectric bottom layer, and the residual area covers a second portion of the substrate adjacent to the first portion; forming a first cover layer on a side of the dielectric cap layer facing the trench; forming a second cover layer on a side of the dielectric bottom layer facing the trench; performing a dry etching process to remove portions of the second cover layer above the second portion to expose the residual area; and etching the residual area to expose the second portion.

Description

Semiconductor device and method for manufacturing the same

The present disclosure relates to a semiconductor device and a method for manufacturing the semiconductor device, and in particular to a method for manufacturing a bit line portion of a capacitor.

In the current process of manufacturing semiconductor components, it is common to use etching technology to form trenches to expose the bonding area to facilitate the next step of wire, conductor connection or filling of other materials. However, the bottom of the trench is often not completely etched. It may be because the depth of the trench is too deep, causing the dry etching plasma to be unable to fully etch the bottom of the trench. Or because during the etching process, when the trench extends to the substrate to expose the bonding area, the residue of the substrate will accumulate and cover the surrounding area, making the area near the substrate difficult to etch. In other words, the bonding area of the substrate cannot be fully exposed, resulting in an increase in resistance.

However, if the etching process time is simply extended to more completely expose the bonding area, the etching solution or etching gas may over-etch other exposed areas of the trench sidewalls and cause damage.

Therefore, how to propose a semiconductor device and a manufacturing method thereof that can solve the above problems is one of the problems that the industry is eager to invest research and development resources to solve.

In view of this, one purpose of the present disclosure is to provide a semiconductor device and a manufacturing method thereof that solves the above-mentioned problem.

The present disclosure relates to a method for manufacturing a semiconductor device, comprising: forming a semiconductor structure, wherein the semiconductor structure comprises a substrate, a dielectric bottom layer, a conductor layer, and a dielectric cap layer stacked in sequence; etching the semiconductor structure to form a trench, wherein the trench penetrates the dielectric cap layer, the conductor layer, and the dielectric bottom layer, and exposes a portion of the substrate located at the center of the bottom of the trench, and the dielectric cap layer is exposed. The residual area of the dielectric bottom layer is formed on both sides of the bottom of the trench, and the residual area has an inclined surface; a covering layer is formed on the side of the dielectric bottom layer facing the trench; the portion of the covering layer covering the residual area is removed and the portion of the covering layer covering the aforementioned side of the dielectric bottom layer facing the trench is retained; and the residual area is etched so that the side of the dielectric bottom layer facing the trench is substantially perpendicular to the substrate.

In some embodiments, forming the capping layer comprises plasma treating the dielectric base layer.

In some embodiments, the step of performing plasma treatment on the dielectric base layer simultaneously forms another capping layer on a side of the dielectric capping layer facing the trench.

In some embodiments, a conductive layer separates a cover layer and another cover layer.

In some embodiments, removing the portion of the capping layer covering the residual area and retaining the portion of the capping layer covering the dielectric base layer toward the aforementioned side of the trench is performed by an anisotropic etching process.

In some embodiments, etching the residual region is performed by an isotropic etching process. In the isotropic etching process, the etching rate of the capping layer is less than the etching rate of the residual region.

The present disclosure relates to a semiconductor element including a substrate, a dielectric bottom layer, a conductor layer and a dielectric cap layer. The dielectric bottom layer is on the substrate. The conductor layer is on the dielectric bottom layer. The dielectric cap layer is on the conductor layer. A trench penetrates the dielectric cap layer, the conductor layer and the dielectric bottom layer, and exposes a portion of the substrate at the bottom of the trench. The dielectric bottom layer includes a first side surface and a second side surface. The first side surface is connected to the substrate, is located on a side of the dielectric bottom layer facing the trench, and extends substantially vertically in a direction away from the substrate. The second side surface is connected between the first side surface and the conductor layer.

In some embodiments, the semiconductor device further includes a cover layer, which covers the second side surface and is located below the conductive layer.

In some embodiments, the cover layer has a triangular outline as viewed from a cross section through the dielectric cap layer, the conductive layer, the dielectric bottom layer, and the substrate.

In some embodiments, the first side surface is flush with a side surface of the cover layer facing the trench.

In summary, since the manufacturing method of the semiconductor device disclosed herein includes forming a first capping layer and a second capping layer, and then removing the second capping layer covering the second portion by a dry etching process, the second portion of the substrate (active region, shallow trench isolation region) can be completely exposed during the etching process without damaging the dielectric capping layer. Since the second portion of the substrate of the semiconductor device disclosed herein is completely exposed, the side surface of the dielectric bottom layer substantially extends vertically away from the surface of the substrate.

These and other aspects of the present disclosure will become apparent from the following description of preferred embodiments in conjunction with the drawings, but variations and modifications may be made therein without departing from the spirit and scope of the novel concepts of the present disclosure.

The following disclosure will be more fully described herein through drawings and references, and some exemplary embodiments are illustrated in the drawings. The disclosure may be implemented in different forms and should not be limited by the embodiments mentioned below. However, these embodiments are provided to help a more complete understanding of the disclosure and to fully convey the scope of the invention to those skilled in the art. The same reference numerals will refer to similar elements throughout the text.

Spatially relative terms (e.g., "below," "beneath," "below," "above," "on," and related terms) are used herein to simply describe the relationship of an element or feature as shown in the figure to another element or feature. These spatially relative terms encompass different orientations of the device in use or operation in addition to the orientation shown in the figure. Furthermore, these devices may be rotated (90 degrees or other angles), and the spatially relative descriptors used herein may be interpreted accordingly. In addition, the term "made of" may mean "comprising" or "consisting of."

Please refer to FIG. 1. FIG. 1 is a flow chart showing a method M for manufacturing a semiconductor device according to an embodiment of the present disclosure. The method M for manufacturing a semiconductor device includes step S10, step S20, step S30, step S40, and step S50. When describing step S10, step S20, step S30, step S40, and step S50 in FIG. 1 in detail, please refer to FIG. 2 to FIG. 6 at the same time. FIG. 2 to FIG. 6 are schematic diagrams showing multiple manufacturing stages of a semiconductor device according to one or more embodiments of the present disclosure.

The operations of step S10, step S20, step S30, step S40 and step S50 are described in detail below.

First, step S10 is performed: forming a semiconductor structure 10.

Please refer to FIG. 2. In this embodiment, the semiconductor structure 10 includes a substrate 100, a dielectric bottom layer 200, a conductor layer 300, and a dielectric cap layer 400 stacked in sequence. The substrate 100 is formed. The substrate 100 may be an active area formed by etching a silicon substrate, such as a shallow trench isolation (STI) area. Then, the dielectric bottom layer 200, the conductor layer 300, and the dielectric cap layer 400 are sequentially deposited on the substrate 100. The dielectric base layer 200, the conductive layer 300 and the dielectric cap layer 400 may be formed by any suitable method, such as CVD (chemical vapor deposition), PECVD (plasma enhanced chemical vapor deposition), PVD (physical vapor deposition), ALD (atomic layer deposition), PEALD (plasma enhanced atomic layer deposition), ECP (electrochemical plating), chemical plating, etc.

In some preferred embodiments, the material of the substrate 100 is silicon, such as polycrystalline silicon. The material of the conductive layer 300 is tungsten (W). The material of the dielectric bottom layer 200 and the dielectric cap layer 400 is a stable dielectric layer that can be further oxidized, such as silicon nitride (SiN). In some embodiments, the dielectric bottom layer 200 and the dielectric cap layer 400 are the same material.

Next, step S20 is performed: etching the semiconductor structure 10 to form a trench 12.

Please refer to FIG. 3. In the present embodiment, an etching process is performed on the semiconductor structure 10 to form a trench 12 penetrating the dielectric cap layer 400, the conductive layer 300 and the dielectric bottom layer 200. The trench 12 separates the block-shaped dielectric cap layer 400, the conductive layer 300 and the dielectric bottom layer 200 into a plurality of bit line features 15 on the active region. The trench 12 is formed to expose the first portion 110 and the second portion 120 of the substrate 100. The first portion 110 and the second portion 120 may be collectively referred to as a contact landing area in subsequent processes. When the contact landing area is too small, the resistance will increase. However, when the etching process extends the trench 12 to the substrate 100, the first portion 110 of the substrate 100 located in the center of the trench 12 will be exposed by the trench 12 earlier than the second portions 120 on both sides, and the exposed first portion 110 will generate residues due to the etching process. The generated residues will cover and accumulate on the dielectric bottom layer 200 on both sides of the bottom of the trench 12 (that is, above the second portion 120), making it difficult for the dielectric bottom layer 200 on both sides of the bottom of the trench 12 to be completely etched and having a residue area 210.

As shown in FIG. 3 , a first portion 110 located at the center of the bottom of the trench 12 is exposed by the trench 12, while a second portion 120 near the two sides of the trench 12 is covered by the residual region 210. In FIG. 3 , the profile of the dielectric bottom layer 200 is substantially trapezoidal, as observed from a cross section that cuts through the dielectric cap layer 400, the conductive layer 300, the dielectric bottom layer 200, and the substrate 100 and is substantially perpendicular to the surface of the substrate 100 near the dielectric bottom layer 200. The dielectric bottom layer 200 includes a portion with a rectangular profile below the conductive layer 300 and residual regions 210 with a triangular profile extending from both sides of the rectangular portion. The residual region 210 has an inclined surface 212 extending from the conductive layer 300 to the substrate 100. The residual region 210 can be defined as a portion of the dielectric bottom layer 200 that is not completely etched and remains above the bonding region (the first portion 110 and the second portion 120). In some embodiments, the first portion 110 is adjacent to the second portion 120. The first portion 110 is located between the two second portions 120. The area ratio of the first portion 110 to the second portion 120 may vary due to the etching process of step S20. The present disclosure is not intended to limit the area ratio of the first portion 110 to the second portion 120.

In some embodiments, the etching process performed in step S20 may be any suitable etching process, such as a wet etching process, a dry etching process, or a combination thereof. Before performing the etching process, one or more mask layers may be deposited on the dielectric cap layer 400. Then, a photolithography process is used to transfer the pattern on the mask to the mask layer to define the portion to be etched (such as the trench 12), and then the etching process is performed.

Next, step S30 is performed: forming a first covering layer 510 and a second covering layer 520 .

Please refer to FIG. 4. In this embodiment, the dielectric cap layer 400 and the dielectric bottom layer 200 are made of the same material. More specifically, the dielectric cap layer 400 and the dielectric bottom layer 200 are both made of silicon nitride (SiN). The dielectric cap layer 400 and the dielectric bottom layer 200 on both sides of the trench 12 are subjected to plasma treatment so that the dielectric cap layer 400 and the dielectric bottom layer 200 facing the trench 12 are oxidized to form a first cap layer 510 and a second cap layer 520 made of silicon oxynitride (SiON). In other words, the first cover layer 510 is formed on the side of the dielectric cover layer 400 facing the trench 12. The second cover layer 520 is formed on the side of the dielectric bottom layer 200 facing the trench 12. Part of the second cover layer 520 is formed on the side of the residual area 210 away from the substrate 100. The first cover layer 510 and the second cover layer 520 are substantially formed at the same time. Some parts of the second cover layer 520 are located below the conductive layer 300, and other parts of the second cover layer 520 are located above the second part 120 of the substrate 100. The conductive layer 300 separates the first cover layer 510 and the second cover layer 520. Portions of the second capping layer 520 above the second portion 120 are formed from portions of the residual region 210 of the dielectric base layer 200 .

In some embodiments, the plasma treatment used to form the first capping layer 510 and the second capping layer 520 uses a process gas containing oxygen (O ₂ ). At a high temperature, the surfaces of the dielectric capping layer 400 and the dielectric bottom layer 200 facing the trench 12 are oxidized by plasma to form the first capping layer 510 and the second capping layer 520. In other embodiments, the plasma treatment may not be used, but the surfaces of the dielectric capping layer 400 and the dielectric bottom layer 200 facing the trench 12 are oxidized in a high temperature environment with oxygen.

In some alternative embodiments, the dielectric cap layer 400 and the dielectric bottom layer 200 may be made of different materials. The dielectric cap layer 400 and the dielectric bottom layer 200 of different materials will form a first cap layer 510 and a second cap layer 520 of different materials. When the dielectric cap layer 400 and the dielectric bottom layer 200 of different materials are subjected to oxidation treatment (e.g., plasma treatment) for the same time, the first cap layer 510 and the second cap layer 520 of different thicknesses will be generated. In other words, the material and thickness of the first cap layer 510 and the second cap layer 520 can be adjusted according to the needs of the process.

Next, step S40 is performed: performing a dry etching process to remove some portions of the second capping layer 520 located above the second portion 120 to expose the residual region 210 .

Please refer to FIG. 5. In this embodiment, a dry etching process is performed on the second capping layer 520 at the bottom of the trench 12 to remove the portion of the second capping layer 520 located above the second portion 120 of the substrate 100, exposing the residual region 210. The surface of the dielectric capping layer 400 facing the trench 12 is still covered by the first capping layer 510. The residual region 210 and the first capping layer 510 simultaneously exposed by the trench 12 have different materials. From a cross-section through the dielectric cap layer 400, the conductive layer 300, the dielectric bottom layer 200, and the substrate 100 and substantially perpendicular to the surface of the substrate 100 close to the dielectric bottom layer 200, the second cover layer 520 remaining below the conductive layer 300 has a triangular outline. When the portion of the second cover layer 520 located above the second portion 120 of the substrate 100 is removed, a portion of the second portion 120 is exposed.

In some preferred embodiments, the etching process of step S40 is an anisotropic etching process, such as a dry etching process. By using the dry etching process, the second cover layer 520 located above the second portion 120 can be removed in a collimated manner without damaging the first cover layer 510 on both sides of the trench 12. When performing the dry etching process, the etching rate of removing the second cover layer 520 is greater than the etching rate of removing the first portion 110 of the substrate 100.

Next, step S50 is performed: etching the residual region 210 to expose the second portion 120 .

Please refer to FIG. 6. In the present embodiment, an etching process is performed on the residual region 210 below the trench 12 to remove the residual region 210. After the residual region 210 is removed, the second portion 120 of the substrate 100 below the residual region 210 is exposed, so that the bonding area is increased. Since the first capping layer 510 covers the surface of the dielectric capping layer 400 facing the side of the trench 12, the dielectric capping layer 400 will not be consumed in the etching process of step S50. In other words, in the etching process of step S50, the residual region 210 has a first etching rate, and the first capping layer 510 has a second etching rate, wherein the first etching rate is greater than the second etching rate. Similarly, in the etching process of step S50, the second capping layer 520 remaining under the conductive layer 300 also has a third etching rate that is less than the first etching rate. Accordingly, the first capping layer 510 and the second capping layer 520 can protect the dielectric capping layer 400 from being consumed in the process of removing the residual region 210. Relatively speaking, the residual region 210 can be removed more completely.

In some preferred embodiments, the etching process of step S50 is an isotropic etching process, such as a wet etching process. By utilizing the etching selectivity between the first capping layer 510 and the second capping layer 520 and the residual region 210, the wet etching process can better remove the residual region 210 without damaging the dielectric capping layer 400 covered and protected by the first capping layer 510.

The structure of the semiconductor device manufactured by the semiconductor device manufacturing method M will be described in detail below.

Please continue to refer to FIG. 6. The semiconductor device shown in FIG. 6 includes a substrate 100, a dielectric bottom layer 200, a conductive layer 300, a dielectric cap layer 400, a first cap layer 510, and a second cap layer 520. The substrate 100 may be a shallow trench isolation (STI) layer of an active region. The dielectric bottom layer 200 includes a connected bottom surface 201, a first side surface 202 connected to the bottom surface 201, and a second side surface 204 connected to the first side surface 202. Since the residual region 210 is removed (see FIG. 5), the second portion 120 is exposed, and the first side surface 202 extends substantially vertically in a direction away from the substrate 100. The first side surface 202 is substantially perpendicular to the bottom surface 201. The first side surface 202 is exposed. The conductor layer 300 is on the dielectric bottom layer 200. The conductor layer 300 is connected to the second side surface 204. The dielectric cap layer 400 is connected to the conductor layer 300. The first cover layer 510 covers the third side surface 402 of the dielectric cap layer 400. The first cover layer 510 is connected to the conductor layer 300. Two second cover layers 520 are connected to opposite sides of the dielectric cap layer 400. The second cover layer 520 is connected to and covers the second side surface 204. The second cover layer 520 is connected to the conductor layer 300. The conductive layer 300 separates the first cover layer 510 and the second cover layer 520. It can be clearly observed that in this embodiment, the trench 12 completely exposes the first portion 110 of the substrate 100 and the second portions 120 on both sides of the first portion 110, and has a complete bonding area.

In the embodiments of the present disclosure, the terms "substantially" and "substantially" may refer to a given value varying within 5%. For example, the first side surface 202 is substantially perpendicular to a surface of the substrate 100 connected to the bottom surface 201, that is, an angle between the first side surface 202 and a surface of the substrate 100 connected to the bottom surface 201 may vary within plus or minus 5% of 90°.

In some embodiments, as shown in FIG. 6 , the dielectric bottom layer 200 of the semiconductor device has a hexagonal outline when viewed from a cross section that passes through the dielectric cap layer 400, the conductive layer 300, the dielectric bottom layer 200, and the substrate 100 and is substantially perpendicular to the surface of the substrate 100 close to the dielectric bottom layer 200. The outline of the second cover layer 520 located between the dielectric bottom layer 200 and the conductive layer 300 is a triangle. The outline of the structure formed by the dielectric bottom layer 200 and the two second cover layers 520 connected to the opposite sides of the dielectric bottom layer 200 is substantially rectangular.

In some embodiments, the semiconductor device shown in FIG. 6 can be further processed to form a bit line structure for dynamic random access memory (DRAM). Subsequent processing may be, for example, connecting the bit line structure to a capacitor or filling the trench 12 with polysilicon.

In summary, since the manufacturing method of the semiconductor device disclosed herein includes the steps of forming the first capping layer and the second capping layer, the residual region of the dielectric bottom layer can be completely removed without damaging the dielectric capping layer. In other words, since the residual region is completely removed, the first side surface of the dielectric bottom layer substantially extends perpendicularly to the substrate, exposing a larger bonding area of the substrate.

The foregoing description is only provided to illustrate and describe the exemplary embodiments of the present disclosure, and is not intended to limit the precise form of the invention disclosed by the present disclosure. The above teachings may be modified or varied.

The embodiments selected and described are used to explain the content of the present disclosure and their practical applications to inspire other technical personnel in the field to utilize the present disclosure and various embodiments, and to make various modifications to meet the expected specific use. Alternative embodiments will be obvious to technical personnel in the field to which the present disclosure belongs without departing from the spirit and scope of the present disclosure. Therefore, the scope of the present invention is determined according to the scope of the attached invention application, rather than being limited by the above specification and the exemplary embodiments described therein.

M: Method for manufacturing semiconductor element S10, S20, S30, S40, S50: Steps 10: Semiconductor structure 12: Trench 100: Substrate 110: First portion 120: Second portion 200: Dielectric bottom layer 201: Bottom surface 202: First side surface 204: Second side surface 210: Residual region 212: Inclined surface 300: Conductor layer 400: Dielectric cap layer 402: Third side surface 510: First cover layer 520: Second cover layer

The drawings illustrate one or more embodiments of the present disclosure and are used together with the written description to explain the principles of the present disclosure. In all drawings, the same drawing marks are used to refer to similar or identical elements of the embodiments as much as possible, wherein: FIG. 1 is a flow chart showing a method for manufacturing a semiconductor element according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram showing a manufacturing stage of a method for manufacturing a semiconductor element according to an embodiment of the present disclosure. FIG. 3 is a schematic diagram showing a manufacturing stage of a method for manufacturing a semiconductor element according to an embodiment of the present disclosure. FIG. 4 is a schematic diagram showing a manufacturing stage of a method for manufacturing a semiconductor element according to an embodiment of the present disclosure. FIG. 5 is a schematic diagram showing a manufacturing stage of a method for manufacturing a semiconductor element according to an embodiment of the present disclosure. Figure 6 is a schematic diagram showing a manufacturing stage of a method for manufacturing a semiconductor device according to an embodiment of the present disclosure.

Domestic storage information (please note in the order of storage institution, date, and number) None Foreign storage information (please note in the order of storage country, institution, date, and number) None

M: Manufacturing method of semiconductor element

S10,S20,S30,S40,S50: Steps

Claims (10)

A method for manufacturing a semiconductor element comprises: forming a semiconductor structure, wherein the semiconductor structure comprises a substrate, a dielectric bottom layer, a conductor layer and a dielectric cap layer stacked in sequence; etching the semiconductor structure to form a trench, wherein the trench penetrates the dielectric cap layer, the conductor layer and the dielectric bottom layer and exposes a portion of the substrate located at the center of the bottom of the trench, and the dielectric bottom layer is exposed. A residual region is formed on both sides of the bottom of the trench, the residual region having a slope; a covering layer is formed on a side of the dielectric bottom layer facing the trench; a portion of the covering layer covering the residual region is removed and another portion of the covering layer covering the side of the dielectric bottom layer facing the trench is retained; and the residual region is etched so that a side of the dielectric bottom layer facing the trench is substantially perpendicular to the substrate. A method for manufacturing a semiconductor device as described in claim 1, wherein the step of forming the covering layer includes performing a plasma treatment on the dielectric bottom layer. A method for manufacturing a semiconductor device as described in claim 2, wherein the step of performing the plasma treatment on the dielectric bottom layer simultaneously forms another covering layer on the side of the dielectric cap layer facing the trench. A method for manufacturing a semiconductor device as described in claim 3, wherein the conductive layer separates the cover layer and the other cover layer. A method for manufacturing a semiconductor device as described in claim 1, wherein the step of removing the portion of the covering layer covering the residual area and retaining the portion of the covering layer covering the dielectric bottom layer facing the side of the trench is performed by an anisotropic etching process. A method for manufacturing a semiconductor device as described in claim 1, wherein the step of etching the residual region is performed by an isotropic etching process, and in the isotropic etching process, the etching rate of the capping layer is greater than the etching rate of the residual region. A semiconductor device comprises: a substrate; a dielectric bottom layer on the substrate; a conductor layer on the dielectric bottom layer; and a dielectric cap layer on the conductor layer, wherein a trench penetrates the dielectric cap layer, the conductor layer and the dielectric bottom layer and exposes a portion of the substrate at the bottom of the trench, wherein the dielectric bottom layer comprises: a first side surface connected to the substrate, located on a side of the dielectric bottom layer facing the trench and extending substantially vertically in a direction away from the substrate; and a second side surface connected between the first side surface and the conductor layer. The semiconductor element as described in claim 7 further comprises: a covering layer covering the second side and located below the conductive layer. A semiconductor device as described in claim 8, wherein the cover layer has a triangular outline when observed from a cross section through the dielectric cover layer, the conductive layer, the dielectric bottom layer, and the substrate. A semiconductor device as described in claim 9, wherein the first side is flush with a side of the covering layer facing the trench.