TWI611468B - Semiconductor devices - Google Patents

Abstract

The present disclosure provides a photomask for ion implantation, the photomask comprising a plurality of light transmissive pattern units and a plurality of opaque pattern units, the light transmissive pattern unit and the opaque pattern unit having an amount in a repeating unit In proportion, the repeating unit is repeatedly arranged along at least one dimension to form a reticle pattern, wherein the light transmissive pattern unit has the same size and the same shape as the opaque pattern unit. Further, the present disclosure also provides a method of ion implantation using the photomask, and a semiconductor device formed using the ion implantation method.

Description

Semiconductor device

The present invention relates to a manufacturing technique of an integrated circuit, and more particularly to a semiconductor device formed by an ion implantation method.

In the fabrication of integrated circuits, the semiconductor material is usually doped by ion implantation to form a doped region of the semiconductor device, such as a source/汲 of a metal oxide semiconductor (MOS) device. Polar zone.

In the ion implantation process, the photoresist coated on the semiconductor wafer is first exposed by a photomask, and then the exposed photoresist is developed to form a patterned photoresist. Conventional reticle for ion implantation usually has a block pattern, and the photoresist pattern formed by using a conventional reticle has an opening completely exposing a region on the semiconductor wafer to be ion implanted, through which the semiconductor wafer is Perform ion implantation. Therefore, when ion implantation is performed using a conventional mask, a mask step can only form an ion implantation concentration region on the semiconductor wafer, and a plurality of ion implantation concentration regions are formed on the semiconductor wafer. , you need to use multiple mask steps to complete.

In the manufacture of integrated circuits, it is often necessary to form a plurality of regions of ion implantation concentration on a semiconductor wafer in response to different electrical requirements of different components. However, the use of conventional ion implantation masks requires multiple masks. The process can form a variety of ion implantation concentration areas on the semiconductor wafer, and the mask cannot be saved. Number and manufacturing cost.

In an embodiment of the present disclosure, a photomask for ion implantation is provided, the photomask includes a plurality of light transmissive pattern units; and a plurality of opaque pattern units, the light transmissive pattern unit and the opaque pattern unit are The first repeating unit has a first quantity ratio, and the first repeating unit is repeatedly arranged along at least one dimension to form a first mask pattern, wherein the light transmissive pattern unit has the same size and the same as the opaque pattern unit shape.

In an embodiment of the present disclosure, there is also provided a method of ion implantation, the method comprising coating a photoresist layer on a semiconductor substrate; providing a photomask for ion implantation as described above, exposing the photoresist layer; Developing the exposed photoresist layer to form a first photoresist pattern having a plurality of openings, the first photoresist pattern corresponding to the opaque pattern units in the first mask pattern, and in the first photoresist pattern The openings correspond to the light transmissive pattern units in the first mask pattern; and the ion implantation of the first conductivity type dopant is performed on the first region of the semiconductor substrate via the openings in the first photoresist pattern A first doped region having a first ion implantation concentration.

Further, in an embodiment of the present disclosure, there is provided a semiconductor device including a semiconductor substrate, a first doped region formed on the semiconductor substrate and having a first ion implantation concentration, the first doped region comprising a plurality of having a first The conductive well region is disposed at a distance from the plurality of well regions having the second conductivity type, and the second doped region is formed on the semiconductor substrate and has a second ion implantation concentration, the second doped region comprising a plurality of The first conductivity type well region is spaced apart from the plurality of well regions having the second conductivity type, wherein the second ion implantation concentration and the first separation The sub-planting concentration is different.

100‧‧‧P type substrate

102‧‧‧P type epitaxial layer

104‧‧‧P type well area

106‧‧ ‧ isolation zone

108‧‧‧ gate

110‧‧‧gate dielectric layer

112‧‧‧ photoresist layer

112P‧‧‧ patterned photoresist layer

113‧‧‧ openings

114‧‧‧Light pattern unit

115‧‧‧resist pattern

116‧‧‧Opacity pattern unit

118‧‧‧First Conductive Well Area

120‧‧‧Second Conductive Well Area

122‧‧‧Doped area

124‧‧‧Ion implantation area

200‧‧‧ mask

200A‧‧‧mask pattern

200U‧‧‧repeating unit

300‧‧‧Exposure process

400‧‧‧Ion implantation process

In order to make the objects, features, and advantages of the present disclosure more comprehensible, the following description will be described in detail with reference to the accompanying drawings. Figures 1-4 show light for ion implantation using the present disclosure in accordance with an embodiment. A cross-sectional schematic view of each intermediate stage of the method of ion implantation by the cover; and 5A-5C, 6A-6C, and 7A-7C are diagrams showing various masks for the photomask for ion implantation in accordance with various embodiments of the present disclosure. A partial plan view of the pattern.

The present disclosure provides various embodiments of the pattern design of a reticle for ion implantation. With the pattern design of the reticle provided by various embodiments of the present disclosure, only one reticle step and one ion implantation step can be used in the semiconductor A plurality of doped regions having different ion implantation densities are formed on the wafer, whereby the number of masks used in the integrated circuit process can be reduced, and manufacturing costs are saved.

1-4 illustrate cross-sectional schematic views of intermediate stages of a method of ion implantation using the reticle 200 for ion implantation in accordance with an embodiment. Referring to FIG. 1, a semiconductor wafer is first provided. In an embodiment, the semiconductor wafer may include a P-type substrate 100. The P-type epitaxial layer 102 is grown on the P-type substrate 100 and formed in the P-type epitaxial layer 102. There is a P-type well region 104, and in addition, an isolation region 106 is formed on the semiconductor wafer, such as shallow trench isolation (STI) or field oxide (FOX). The component area on the semiconductor wafer can be defined by the arrangement of the isolation region 106. In addition, a gate 108 and a gate dielectric layer 110 are also formed on the P-type well region 104. In the present embodiment, ion implantation is performed using the photomask 200 for ion implantation of the present disclosure to form a source/drain region of an N-type metal oxide semiconductor device (NMOS). In other embodiments, the photomask 200 for ion implantation of the present disclosure may also be used for ion implantation to form various doping regions of other types of components. Further, the structure of the above semiconductor wafer is merely exemplary. It is intended to illustrate the embodiments of the present disclosure and is not intended to limit the disclosure.

As shown in FIG. 1, the photoresist layer 112 is coated on the semiconductor wafer, and the photoresist layer 112 is exposed to the photomask 200 for ion implantation, and the photomask 200 has a plurality of exposure processes on the photomask 200. a reticle pattern 200A corresponding to a region on the semiconductor wafer where ion implantation is to be performed, although only two reticle patterns 200A are depicted in FIG. 1, however, various embodiments in accordance with the present disclosure There may be more than two reticle patterns 200A on the reticle 200 for ion implantation, and these reticle patterns 200A may have different pattern designs, respectively, to apply different ion implantation concentrations on different components. Various doped regions, or various doped regions with different ion implantation concentrations on the same component. In addition, the two mask patterns 200A shown in FIG. 1 may have the same pattern design, thereby forming source/drain regions of the same ion implantation concentration in the P-type well region 104; or in FIG. The two reticle patterns 200A shown in the above may have different pattern designs, respectively, thereby forming source/drain regions having different ion implantation densities in the P-type well region 104.

In accordance with an embodiment of the present disclosure, the reticle pattern 200A on the reticle 200 has a plurality of light transmissive pattern elements 114 and a plurality of opaque pattern sheets In the element 116, the light transmissive pattern unit 114 has the same size and the same shape as the opaque pattern unit 116, and the light transmissive pattern unit 114 and the opaque pattern unit 116 have an amount in one repeating unit of the reticle pattern 200A. The ratio, for example, the ratio of the number of the light-transmitting pattern unit 114 and the opaque pattern unit 116 in the repeating unit may be 1:1, 2:1, 3:1 or any other ratio, which is determined by the design requirements of the component. Decide. The repeating unit is repeatedly arranged along at least one dimension to form a reticle pattern 200A. After ion implantation by using the reticle pattern 200A, the ion implantation concentration of the doped region formed by the opaque pattern unit is The number of 114 and the opaque pattern unit 116 are proportionally controlled within a repeating unit of the reticle pattern 200A.

Next, please refer to FIGS. 5A-5C, which are partial plan views showing various reticle patterns 200A of the reticle 200 for ion implantation in accordance with various embodiments of the present disclosure. As shown in FIG. 5A, in an embodiment, the light transmissive pattern unit 114 and the opaque pattern unit 116 of the reticle pattern 200A are strips, and a repeating unit 200U constituting the reticle pattern 200A is formed. It is composed of an elongated light-transmissive pattern unit 114 and an elongated opaque pattern unit 116, and the repeating unit 200U is repeatedly arranged along a one-dimensional direction, for example, an X-axis direction, to form a fence pattern. A mask pattern 200A of a fence-shaped pattern. The number of repeating units 200U constituting the reticle pattern 200A may be arbitrarily adjusted in order to meet the requirements of the ion implantation areas of different areas. Further, the pattern at the boundary of the reticle pattern 200A may be an incomplete repeating unit 200U, that is, The pattern located at the boundary of the reticle pattern 200A may include only a portion of the light transmissive pattern unit 114 and/or a portion of the opaque pattern unit 116.

Since the reticle pattern 200A of the reticle 200 for ion implantation of the present disclosure is constituted by the repeating unit 200U including the light transmitting pattern unit 114 and the opaque pattern unit 116, when the size of the element is changed, only adjustment is required. The number of repeating units 200U can match the size of the components, and thus does not increase the difficulty of the mask layout.

Referring to FIG. 5B, in an embodiment, the light transmissive pattern unit 114 and the opaque pattern unit 116 of the reticle pattern 200A are both hexagonal, and one repeating unit 200U of the reticle pattern 200A is formed by a hexagon. The light transmissive pattern unit 114 is composed of a hexagonal opaque pattern unit 116 which is repeatedly arranged in a two-dimensional direction, for example, an X-axis and a Y-axis direction, to form a honeycomb-like mosaic pattern (beehive- Shaped mosaic pattern) reticle pattern 200A.

Referring to FIG. 5C, in an embodiment, the light transmissive pattern unit 114 and the opaque pattern unit 116 of the reticle pattern 200A are both quadrangular, and one repeating unit 200U of the reticle pattern 200A is formed by a quadrilateral transparent pattern unit. 114 is composed of a quadrangular opaque pattern unit 116 which is repeatedly arranged in a two-dimensional direction, for example, an X-axis and a Y-axis direction, to constitute light having a chessboard-shaped mosaic pattern. Cover pattern 200A.

In the embodiment of FIGS. 5A-5C, one repeating unit 200U of the reticle pattern 200A is composed of one light transmissive pattern unit 114 and one opaque pattern unit 116, but by changing the light transmissive pattern unit 114 or not The shape of the light transmissive pattern unit 116 and/or the manner in which the light transmissive pattern unit 114 and the opaque pattern unit 116 are arranged may be subsequent to the second conductivity type well region. When the ion implantation of the dopant of the first conductivity type is performed, various doping regions different in the distribution state of the second conductivity type well region and the first conductivity type well region are generated.

Referring to FIG. 2, in an embodiment, the photoresist layer 112 on the semiconductor wafer can be exposed and developed using the mask pattern 200A provided in FIGS. 5A-5C to form a patterned photoresist layer 112P. It has a plurality of openings 113 and a plurality of photoresist patterns 115. In an embodiment, the photoresist layer 112 may be a positive photoresist, and the patterned photoresist layer 112P has a photoresist pattern 115 corresponding to the mask pattern 200A, that is, the opening 113 corresponds to the mask pattern 200A. The light-transmitting pattern unit 114, and the photoresist pattern 115 corresponds to the opaque pattern unit 116 in the reticle pattern 200A. On the other hand, in another embodiment, the photoresist layer 112 may be a negative photoresist, and the patterned photoresist layer 112P has a photoresist pattern opposite to the mask pattern 200A, that is, the opening 113 corresponds to the mask pattern. The opaque pattern unit 116 in 200A, and the photoresist pattern 115 corresponds to the light transmissive pattern unit 114 in the reticle pattern 200A.

As shown in FIG. 2, after the patterned photoresist layer 112P is formed, an ion implantation process 400 is performed on the semiconductor wafer. In one embodiment, the first conductivity type dopant ion beam, for example, The ion beam of the N-type dopant can be implanted into the well region 104 of the second conductivity type via the opening 113 of the patterned photoresist layer 112P, such as a P-type well region, and reaches a specific depth, which can be made by the first conductive The energy of the ion beam of the type of dopant is determined.

After the ion implantation process 400 is completed, a doping region 122 as shown in FIG. 3 is formed. The doping region 122 includes a plurality of first conductivity type well regions 118, for example, an N-type well region, and a plurality of second conductivity types. The well area 120 is, for example, a P-type well area, and the first conductive type well area 118 and the second conductive type well area 120 are inter The first conductive type well region 118 and the second conductive type well region 120 in the doping region 122 have an area ratio which is different from the light transmitting pattern in a repeating unit 200U of the reticle pattern 200A. The ratio of the number of the cells 114 to the opaque pattern unit 116 is substantially the same. To use the reticle pattern 200A of the 5A-5C diagram as an example, the first conductive well region 118 in the doped region 122 is formed. The area ratio of the second conductivity type well region 120 is also about 1:1, and the ion implantation concentration of the doping region 122 is controlled by the area ratio of the first conductivity type well region 118 and the second conductivity type well region 120.

Referring to FIG. 4, in an embodiment, after the ion implantation process is completed, the semiconductor wafer may be subjected to a thermal diffusion process to allow five of the N-type well regions 118 in the doped region 122 shown in FIG. The valence implant ions and the trivalent implant ions in the P-type well region 120 are mutually neutralized via thermal diffusion to obtain an ion implantation region 124 as shown in FIG. 4, and in the ion implantation region 124, the N-type doping The ion implantation concentration of the debris is about 50%. In this embodiment, the ion implantation region 124 is the source/drain region of the NMOS device.

Compared to the conventional photomask for ion implantation, the ion implantation density of the doped region can be reduced or adjusted when ion implantation is performed using the photomask of the present disclosure. Since the conventional reticle has a block pattern corresponding to the ion implantation region, the opening of the patterned photoresist layer formed completely exposes the ion implantation region, so that the ions of the first conductivity type such as the N-type dopant are subsequently performed. When implanted, the ion implantation area generated by the ion implantation area is completely N-type well area, that is, the ion implantation concentration of the N-type dopant in the ion implantation area obtained by using the conventional mask is about 100%, so the use The traditional reticle cannot adjust the ion implantation density by a reticle step and an ion implantation step, and an additional reticle is needed to change the ion cloth. Plant concentration leads to increased manufacturing costs.

Referring to FIGS. 6A-6C, in the embodiment of FIGS. 6A-6C, the repeating unit 200U of the reticle pattern 200A is composed of two transparent pattern units 114 and one opaque pattern unit 116, that is, at the 6A. In the repeating unit 200U of the embodiment of the -6C diagram, the ratio of the number of the light transmitting pattern unit 114 to the opaque pattern unit 116 is 2:1. As shown in FIG. 6A, the light transmissive pattern unit 114 and the opaque pattern unit 116 of the reticle pattern 200A are strips, and the two strip-shaped transparent pattern units 114 and one strip shape are not The repeating unit 200U composed of the light transmitting pattern unit 116 is repeatedly arranged in a one-dimensional direction, for example, an X-axis direction, to constitute a mask pattern 200A having a fence-shaped pattern.

As shown in FIG. 6B, the light transmissive pattern unit 114 and the opaque pattern unit 116 of the reticle pattern 200A are all hexagonal, and are composed of two hexagonal transparent pattern units 114 and a hexagonal opaque pattern. The repeating unit 200U composed of the unit 116 is repeatedly arranged in a two-dimensional direction, for example, an X-axis and a Y-axis direction, to constitute a mask pattern 200A having a honeycomb mosaic pattern.

As shown in FIG. 6C, the light transmissive pattern unit 114 and the opaque pattern unit 116 of the reticle pattern 200A are all quadrangular, and the repeating unit consists of two quadrangular light transmissive pattern units 114 and one quadrangular opaque pattern unit 116. The 200U is repeatedly arranged in a two-dimensional direction, for example, an X-axis and a Y-axis direction, to constitute a mask pattern 200A having a checkerboard mosaic pattern.

In the embodiment of FIG. 6A-6C, the repeating unit 200U of the reticle pattern 200A is composed of two transparent pattern units 114 and one opaque pattern unit 116, that is, the light transmitting pattern unit in the repeating unit 200U. The ratio of the number of 114 to the opaque pattern unit 116 is 2:1, so the use of the 6A-6C In an embodiment in which the reticle pattern 200A of the figure is ion implanted, in the ion implantation of the P-type well region using the N-type dopant, in the doped region 122 shown in FIG. 3, the N-type The area ratio of the well region 118 to the P-type well region 120 is also about 2:1, and the ion implantation concentration of the doped region 122 is controlled by the area ratio of the N-type well region 118 and the P-type well region 120.

Thereafter, the doping region 122 shown in FIG. 3 is subjected to a thermal diffusion process, and the sixth embodiment is used to perform ion implantation of the N-type dopant using the mask pattern 200A of FIGS. 5A-5C. In the embodiment in which the mask pattern 200A of the -6C pattern is subjected to ion implantation of an N-type dopant, an ion implantation region 124 having a high ion implantation concentration (about 67%) of the N-type dopant can be obtained.

Referring to FIGS. 7A-7C, in the embodiment of FIGS. 7A-7C, the repeating unit 200U of the reticle pattern 200A is composed of three light transmissive pattern units 114 and one opaque pattern unit 116, that is, at the 7A. In the repeating unit 200U of the -7C diagram, the number ratio of the light transmissive pattern unit 114 to the opaque pattern unit 116 is 3:1. As shown in FIG. 7A, the light transmissive pattern unit 114 and the opaque pattern unit 116 of the reticle pattern 200A are each elongated, and are formed by three elongated stripe pattern units 114 and one strip opaque pattern. The repeating unit 200U composed of the units 116 is repeatedly arranged in a one-dimensional direction, for example, an X-axis direction, to constitute a mask pattern 200A having a fence pattern.

As shown in FIG. 7B, the light transmissive pattern unit 114 and the opaque pattern unit 116 of the reticle pattern 200A are all hexagonal, and are composed of three hexagonal transparent pattern units 114 and a hexagonal opaque pattern. The repeating unit 200U composed of the unit 116 is repeatedly arranged in a two-dimensional direction, for example, an X-axis and a Y-axis direction, to constitute a mask pattern 200A having a honeycomb mosaic pattern.

As shown in FIG. 7C, the light transmissive pattern unit 114 and the opaque pattern unit 116 of the reticle pattern 200A are all quadrangular, and the repeating unit consists of three quadrangular light transmissive pattern units 114 and one quadrangular opaque pattern unit 116. The 200U is repeatedly arranged in a two-dimensional direction, for example, an X-axis and a Y-axis direction, to constitute a mask pattern 200A having a checkerboard mosaic pattern.

In the embodiment of the 7A-7C diagram, the repeating unit 200U of the reticle pattern 200A is composed of three light transmissive pattern units 114 and one opaque pattern unit 116, that is, the repeating unit in the 7A-7C diagram. In 200U, the ratio of the number of the light-transmitting pattern unit 114 to the opaque pattern unit 116 is 3:1, so after ion implantation using the mask pattern 200A of the seventh embodiment 7A-7C, the N-type dopant pair is used. In an embodiment in which the well region is subjected to ion implantation, in the doped region 122 shown in FIG. 3, the area ratio of the N-type well region 118 to the P-type well region 120 is about 3:1, and the doped region The ion implantation concentration of 122 is controlled by the ratio of the area of the N-type well region 118 to the P-type well region 120.

Thereafter, the doping region 122 shown in FIG. 3 is subjected to a thermal diffusion process, and the seventh embodiment is used to perform ion implantation of the N-type dopant using the mask pattern 200A of FIGS. 6A-6C. The etch mask pattern 200A of the -7C pattern is subjected to ion implantation of an N-type dopant, and an ion implantation region 124 having a higher ion implantation concentration (about 75%) of the N-type dopant can be obtained.

In the above embodiment, the shape, the number ratio, and the arrangement of the light transmissive pattern unit 114 and the opaque pattern unit 116 constituting the repeating unit 200U of the reticle pattern 200A are merely exemplary, and are used to explain the present disclosure. In other embodiments, other shapes than the elongated shape, the hexagonal shape, and the quadrangular shape may be used as the light transmissive pattern unit 114 and the opaque pattern. The element 116 is not limited to the shape exemplified in the above embodiment, and the light-transmitting pattern unit 114 and the opaque pattern unit 116 may also constitute the repeating unit 200U in other quantitative ratios, and is not limited to the number ratios listed in the above embodiments. . In addition, in addition to the arrangement of the barrier pattern and the mosaic pattern shown in the above embodiments, in other embodiments, other arrangements may be adopted, and are not limited to the arrangement listed in the above embodiments, as long as The light-transmitting pattern unit 114 and the opaque pattern unit 116 in the reticle pattern 200A are arranged in a uniformly distributed state, and the light-transmitting pattern unit 114 and the opaque pattern unit 116 in the reticle pattern 200A are The evenly distributed state can achieve a better uniformity of ion implantation in the subsequently generated ion implantation zone.

Although the ion implantation of the source/drain regions of the NMOS device is exemplified in the above embodiment, the pattern design of the reticle for ion implantation of the present disclosure can also be applied to other types of semiconductor devices. , for example, a PMOS device. In addition, by using the pattern design of the reticle of the present disclosure, a plurality of reticle patterns of various quantity ratios can be generated on the reticle by controlling the ratio of the number of the light-transmitting pattern unit and the opaque pattern unit in the repeating unit. Through a mask step and an ion implantation step, a plurality of doped regions having a plurality of ion implantation concentrations can be generated on the semiconductor wafer, and the doping regions of different ion implantation concentrations can be applied to the same component or On different components. Thus, embodiments of the present disclosure can reduce the number and steps of reticle and reduce manufacturing costs compared to using a conventional reticle to create multiple doped regions of various ion implantation densities.

In addition, the pattern design of the reticle of the present disclosure can improve the manufacturing process of the integrated circuit, and the efficiency of the ion implantation can be improved by controlling the ratio and arrangement of the light-transmitting pattern unit and the opaque pattern unit in the reticle pattern. Achieve better For example, compared to an ultra-high voltage platform NMOS device fabricated using a conventional photomask, the fabrication of an ultra-high voltage platform NMOS device using the reticle of the present disclosure can increase the breakdown voltage of the device, for example, from 30 volts to 51 volts. And it is also possible to reduce the channel length of the element, for example, from 10 μm to 5 μm, and therefore, the pattern design of the reticle of the present disclosure can further enhance the performance of the element.

While the present invention has been described in its preferred embodiments, it is not intended to limit the invention, and it is understood by those of ordinary skill in the art that Retouching. Accordingly, the scope of the invention is defined by the scope of the appended claims.

100‧‧‧P type substrate

102‧‧‧P type epitaxial layer

104‧‧‧P type well area

106‧‧ ‧ isolation zone

108‧‧‧ gate

110‧‧‧gate dielectric layer

118‧‧‧First Conductive Well Area

120‧‧‧Second Conductive Well Area

122‧‧‧Doped area

Claims (6)

A semiconductor device comprising: a semiconductor substrate; a first doped region formed on the semiconductor substrate and having a first ion implantation concentration, wherein the first doped region comprises a plurality of first conductivity types The well region is disposed at a distance from the plurality of well regions having a second conductivity type; and a second doped region is formed on the semiconductor substrate and has a second ion implantation concentration, wherein the second doping region comprises A plurality of well regions having the first conductivity type are spaced apart from a plurality of well regions having the second conductivity type, and the second ion implantation concentration is different from the first ion implantation concentration. The semiconductor device of claim 1, wherein the first conductivity type well region and the second conductivity type well regions have a first area ratio in the first doping region, and The first ion implantation concentration of the first doped region is controlled by the first area ratio. The semiconductor device of claim 2, wherein the first conductivity type well region and the second conductivity type well regions have a second area ratio in the second doping region, The second ion implantation concentration of the second doped region is controlled by the second area ratio, and the second area ratio is different from the first area ratio. The semiconductor device according to claim 1, wherein the first conductivity type is a P type, and the second conductivity type is an N type; or the first conductivity type is an N type, and the second conductivity type is P type. The semiconductor device of claim 1, wherein the first doping The region and the second doped region are disposed on the same element. The semiconductor device of claim 1, wherein the first doped region and the second doped region are disposed on different elements.