TWI549298B - Semiconductor device having epitaxial structures - Google Patents

Description

Semiconductor component having epitaxial structure

The present invention relates to a semiconductor device having an epitaxial structure, and more particularly to a metal-oxide-semiconductor (MOS transistor) having an epitaxial source/drain.

Epitaxial structures are widely used in semiconductor processes. For example, conventional techniques often use selective epitaxial growth (SEG) techniques to form a lattice arrangement and substrate in a single crystal substrate. The same epitaxial layer, such as a silicon germanium (SiGe) epitaxial layer, acts as a raised source/drain, or as a recessed source/drain. The lattice constant of the germanium epitaxial layer is greater than that of the germanium substrate lattice, and the germanium epitaxial layer stresses the channel region of the MOS transistor, thereby increasing the carrier mobility of the channel region (carrier) Mobility) and thereby increase the speed of the MOS transistor.

The use of a germanium epitaxial layer as a source/drain can effectively improve component performance, but the fabrication of the germanium epitaxial layer greatly increases the complexity of the semiconductor process and the difficulty of process control. For example, although the germanium content in the germanium epitaxial layer is higher, it can generate greater stress on the channel region. However, considering the effect of niobium content on the critical thickness of the epitaxial layer and the negative effect of the stress relaxation effect of the epitaxial layer on the element beyond the critical thickness, the niobium content in the epitaxial layer Can not increase without limit. In addition to the high and low control of the bismuth content, the bismuth layer is still facing the subsequent metal silicide process, and the metal easily forms agglomeration with the bismuth in the epitaxial layer, causing junction leakage. )The problem. In addition, the prior art has observed that the interface lattice constant of the epitaxial layer and the germanium substrate is too large, causing a sudden roll-off of the component threshold voltage.

It can be seen that although the presence of the germanium epitaxial layer can effectively improve the component performance, there are still many areas for improvement.

Accordingly, it is an object of the present invention to provide a semiconductor device having an epitaxial structure which can improve the above problems.

According to the patent application scope of the present invention, there is provided a semiconductor device having an epitaxial structure, the semiconductor device comprising a gate structure disposed on a substrate, and a protrusion disposed in the substrate on both sides of the gate structure a crystal structure, and an undoped cover layer disposed on the epitaxial structure. The epitaxial structure includes a doping material, a first semiconductor material and a second semiconductor material, the first semiconductor material having a first lattice constant, the second semiconductor material having a second lattice constant, and the The second lattice constant is greater than the first lattice constant, and the undoped cladding layer also includes the first semiconductor material and the second semiconductor material. The second semiconductor material has a first concentration in the epitaxial structure, the second semiconductor material in the undoped cap layer has at least a second concentration, and the second concentration is less than the first concentration.

According to the patent application scope of the present invention, there is further provided a semiconductor device having an epitaxial structure, the semiconductor device comprising a gate structure disposed on a substrate, and a pair of the substrate disposed on both sides of the gate structure a recess, an epitaxial structure respectively disposed in the recess on both sides of the gate structure, and an undoped underlayer formed in the recess, and the undoped underlayer is disposed on the epitaxial layer Between the structure and the substrate. The epitaxial structure includes a doping material, a first semiconductor material and a second semiconductor material, the first semiconductor material having a first lattice constant, the second semiconductor material having a second lattice constant, and the The second lattice constant is greater than the first lattice constant. The undoped underlayer covers the sidewall of the recess and the bottom of the recess and includes the first semiconductor material and the second semiconductor material. The second semiconductor material has a first concentration in the epitaxial structure, the second semiconductor material in the undoped underlayer has at least a second concentration, and the second concentration is less than the first concentration.

According to the semiconductor element having an epitaxial structure provided by the present invention, the epitaxial structure can serve as a source/drain of the semiconductor element. The surface of the epitaxial structure is formed with an undoped cap layer having a lower germanium concentration, thereby avoiding the problem that the metal is easily agglomerated with germanium in the epitaxial layer during the metal telluride process, thereby causing leakage of the junction. In addition, the epitaxial semiconductor device provided by the present invention is provided with a lower concentration of undoped underlayer between the epitaxial structure in the recess and the substrate to avoid the connection between the epitaxial layer and the germanium substrate. The difference in the lattice arrangement of the face is too large, which in turn causes a sudden drop in the starting voltage of the component.

Please refer to FIG. 1. FIG. 1 is a schematic view showing a first preferred embodiment of a semiconductor device having an epitaxial structure according to the present invention. As shown in FIG. 1, the semiconductor device 100 having an epitaxial structure according to the preferred embodiment includes a substrate 102, and a gate structure 110 is disposed on the substrate 102. The gate structure 110 includes a gate insulating layer 112, which may comprise a high dielectric constant (high-k) material or tantalum oxide. The gate structure 110 also includes a gate electrode 114 defined by a patterned hard mask 116, which may comprise a metallic material or a polysilicon. The semiconductor device 100 further includes a lightly doped drain (LDD) 118 disposed in the substrate 102 on both sides of the gate structure 110, a sidewall spacer 120 disposed on the sidewall of the gate structure 110, and a pair of settings. In the substrate 102 on both sides of the gate structure 110, in particular, grooves 122 are provided in the substrate 102 on both sides of the sidewall spacer 120.

Please continue to see Figure 1. After the substrate 102 completes a cleaning step to remove the native oxide or other impurities, a selective epitaxial growth (SEG) method is performed to form an epitaxial structure 130 in the recess 122, respectively. In other words, the semiconductor device 100 of the preferred embodiment further includes an epitaxial structure 130 disposed in the substrate 102 on both sides of the gate structure 110, especially the recess 122 of the substrate 102 on both sides of the gate structure 110. Inside. The epitaxial structure 130 includes a first semiconductor material and a second semiconductor material, the first semiconductor material has a first lattice constant, the second semiconductor material has a second lattice constant, and the second lattice constant Greater than the first lattice constant. In the preferred embodiment, the first semiconductor material may comprise germanium and the second semiconductor material may comprise germanium. That is, the epitaxial structure 130 includes germanium, but is not limited thereto. In addition, the concentration of the second semiconductor material in the preferred embodiment, that is, the concentration of germanium in the epitaxial germanium material may be 36%, but is not limited thereto. By using the lattice constant of germanium to be larger than the lattice constant of the substrate 102, the epitaxial layer is structurally strained as a strained crucible structure, and drives the lattice and band structure of the single crystal germanium in the channel region. A change in the band structure can increase the carrier mobility of the channel region and improve the performance of the semiconductor device 100. In addition, as shown in FIG. 1, the surface of the epitaxial structure 130 is not coplanar with the surface of the substrate 102, and the surface of the epitaxial structure 130 is higher than the surface of the substrate 102.

In addition, an ion implantation process may be performed before the epitaxial structure 130 is formed, after the epitaxial structure 130 is formed, or even when the epitaxial structure 130 is formed, to obtain the p-type or n-type dopant required for the semiconductor device 100. The implant enters the epitaxial structure 130 such that the epitaxial structure 130 includes the p-type or n-type dopant required for the semiconductor device 100 and serves as a source/drain of the semiconductor device 100. Since the ion implantation process described above and the optional doping system are known to those skilled in the art, they are not described herein.

As described above, in order to avoid the problem of junction leakage caused by the formation of agglomerates between the metal and the epitaxial structure 130 in the metal telluride process, a cover layer may be formed on the surface of the epitaxial structure 130, such as a pure The cover layer of the crucible (not shown) serves as a reaction site for the metal telluride process. However, since the germanium concentration in the pure germanium coating layer is 0%, and the germanium concentration in the epitaxial structure 130 is 36%, the difference between the two is too large, so that the pure germanium coating layer easily generates a wavy surface. For example, the surface of a pure tantalum coating layer is detected by an atomic force microscope (AFM), and the root mean square roughness of the pure tantalum coating layer is about 4.21 nm. (nanometer, hereinafter referred to as nm). This rough surface is not conducive to subsequent processes, and even affects the stress of the underlying epitaxial structure 130.

It can be seen that the epitaxial structure 130 without the pure germanium cap layer may cause agglomeration; and the cap layer having the germanium concentration and the epitaxial structure 130 is too large to cause a rough surface, which is unfavorable for subsequent processes. In order to solve this dilemma, the preferred embodiment provides an undoped undoped cap layer 140 disposed on the epitaxial structure 130. The undoped cap layer 140 also includes the first semiconductor material and the second semiconductor material described above, ie, containing germanium. In the preferred embodiment, the undoped cap layer 140 is a single film layer as shown in FIG. 1 , and the concentration of the second semiconductor material in the undoped cap layer 140 is less than that of the epitaxial layer. The concentration of germanium in structure 130 can be, for example, equal to 25%. In addition, the thickness of the undoped cap layer 140 in the preferred embodiment may be 150 angstroms, but is not limited thereto.

In addition, the semiconductor device 100 of the preferred embodiment further includes an undoped underlayer 150 disposed in the recess 122 and disposed between the substrate 102 and the epitaxial structure 130. The undoped underlayer 150 covers the bottom and sidewalls of the recess 122. The bottom layer 150 can be a single film layer or a composite film layer, and includes the first semiconductor material and the second semiconductor material described above, that is, containing germanium. The concentration of the second semiconductor material in the undoped bottom layer 150, that is, the germanium concentration is less than the germanium concentration of the epitaxial structure 130, and is between 10 and 25%, and the germanium concentration is increased from bottom to top. The features of the undoped underlayer 150 will be described in detail in the subsequent embodiments, and thus are not described herein.

According to the semiconductor device 100 having an epitaxial structure according to the first preferred embodiment, the surface of the epitaxial structure 130 is formed with a single film layer of a non-pure germanium undoped cap layer 140. The undoped cap layer 140 contains ruthenium and the ruthenium concentration is preferably 25%. Since the germanium concentration of the undoped cap layer 140 is 25%, and the germanium concentration of the epitaxial structure 130 is 36%, the difference between the two is low, so that the undoped cap layer 140 formed on the surface of the epitaxial structure 130 can obtain one. A relatively flat surface. The surface of the undoped cap layer 140 is detected by AFM, and the root mean square surface roughness of the undoped cap layer 140 is about 0.75 nm, which is comparable to the root mean square surface roughness (4.21 nm) of the pure germanium cap layer. In comparison, the surface roughness is greatly improved. In addition, since the germanium concentration of the undoped cap layer 140 is low, the problem of agglomeration of the metal and the germanium in the metal telluride process can also be reduced.

Next, please refer to FIG. 2, which is a schematic view showing a second preferred embodiment of a semiconductor device having an epitaxial structure according to the present invention. It is to be noted that in the second preferred embodiment, the same components as those of the first preferred embodiment are denoted by the same reference numerals. As shown in FIG. 2, the semiconductor device 100 having an epitaxial structure provided by the preferred embodiment includes a substrate 102, and a gate structure 110 is disposed on the substrate 102. The gate structure 110 includes a gate insulating layer 112, which may comprise a high-k material or tantalum oxide. The gate structure 110 also includes a gate electrode 114 defined by a patterned hard mask 116, which may comprise a metallic material or a polysilicon. The semiconductor device 100 further includes LDDs 118 disposed in the substrate 102 on both sides of the gate structure 110, a sidewall spacer 120 disposed on the sidewall of the gate structure 110, and a pair of substrates 102 disposed on opposite sides of the gate structure 110. In particular, grooves 122 are provided in the substrate 102 on both sides of the side wall sub-120.

Please continue to see Figure 2. The semiconductor device 100 of the preferred embodiment further includes an epitaxial structure 130 disposed in the substrate 102 on both sides of the gate structure 110, particularly in the recess 122 of the substrate 102 on both sides of the gate structure 110. The epitaxial structure 130 includes a first semiconductor material and a second semiconductor material, the first semiconductor material has a first lattice constant, the second semiconductor material has a second lattice constant, and the second lattice constant Greater than the first lattice constant. In the preferred embodiment, the first semiconductor material may comprise germanium and the second semiconductor material may comprise germanium. That is, the epitaxial structure 130 includes germanium. In addition, the concentration of the second semiconductor material in the preferred embodiment, that is, the concentration of germanium in the epitaxial germanium material may be 36%, but is not limited thereto. Further, as shown in FIG. 2, the surface of the epitaxial structure 130 is higher than the surface of the substrate 102.

As described above, in order to solve the aforementioned dilemma, the preferred embodiment provides an undoped cap layer 140 disposed on the epitaxial structure 130. It should be noted that, in the preferred embodiment, the undoped cover layer 140 is a composite film layer as shown in FIG. 2, and the undoped cover layer 140 includes at least a first single layer 140a and a second single The layer 140b and the first single layer 140a are formed between the second single layer 140b and the epitaxial structure 130. The undoped cap layer 140 (including the first monolayer 140a and the second monolayer 140b) also includes the first semiconductor material and the second semiconductor material described above, that is, including germanium. The crucible in the first single layer 140a has a first concentration, and the crucible in the second monolayer 140b has a second concentration, the first concentration and the second concentration are both lower than the germanium concentration of the epitaxial structure 130, and the second The concentration is lower than the first concentration. In the preferred embodiment, the first concentration is preferably 25% and the second concentration is preferably 0%. In other words, the second preferred embodiment provides a composite cover layer 140 having a reduced concentration of germanium from bottom to top. In addition, the thickness of the undoped cap layer 140 in the preferred embodiment may be 150 angstroms, but is not limited thereto. It should be noted that in the preferred embodiment, the thickness of the first single layer 140a has a ratio to the thickness of the second single layer 140b, and the ratio is approximately equal to 1:2.

As described above, the semiconductor device 100 provided by the preferred embodiment further includes an undoped underlayer 150. The features of the undoped underlayer 150 will be described in detail in the subsequent embodiments, and thus are not described herein.

According to the semiconductor device 100 having an epitaxial structure according to the second preferred embodiment, the surface of the epitaxial structure 130 is formed with an undoped cap layer 140 of a composite film layer. The composite cover layer 140 includes a first single layer 140a and a second single layer 140b. The first single layer 140a and the second single layer 140b each include a crucible, and the first single layer 140a preferably has a germanium concentration of 25%. The germanium concentration in the single layer 140b is preferably 0%, and the thickness of the second single layer 140b is greater than the thickness of the first single layer 140a. That is to say, the composite cover layer 140 is a composite film layer whose concentration is decreased from bottom to top. The first single layer 140a of the undoped cap layer 140 has a germanium concentration of 25%, and is disposed between the second single layer 140b having a germanium concentration of 0% and the epitaxial structure 130 having a germanium concentration of 36%, so that it can be used as two The buffer layer, and thus the composite cover layer 140 formed on the surface of the epitaxial structure 130, can obtain a relatively flat surface. The surface of the composite cover layer 140 is detected by AFM, and the root mean square surface roughness of the composite cover layer 140 is about 0.76 nm, which is compared with the root mean square surface roughness (4.21 nm) of the pure tantalum cover layer. The roughness is greatly improved. In addition, since the germanium concentration in the second single layer 140b of the composite cover layer 140 is 0%, the second single layer 140b can be used as a reaction site for the metal telluride process, and the metal and the metal telluride process can be fundamentally avoided. The problem of agglomeration is formed.

Referring to FIG. 3, FIG. 3 is a schematic view showing a third preferred embodiment of a semiconductor device having an epitaxial structure according to the present invention. It should be noted that in the third preferred embodiment, the same components as the first preferred embodiment, such as the substrate 102, the gate structure 110, the LDD 118, the sidewall spacers 120, the recesses 122, and the recesses 122 are formed in the recesses 122. The epitaxial structure 130 is illustrated by the same reference numerals. The components included in the semiconductor device provided in the third preferred embodiment are the same as the second preferred embodiment in the first preferred embodiment, and therefore will not be described again, but only preferred. The embodiment is different from the first preferred embodiment and the second preferred embodiment described above. Please continue to see Figure 3. As described above, the epitaxial structure 130 included in the semiconductor device 100 provided by the preferred embodiment also includes germanium. In addition, the concentration of the second semiconductor material in the preferred embodiment, that is, the concentration of germanium in the epitaxial germanium material may be 36%, but is not limited thereto. Further, as shown in FIG. 3, the surface of the epitaxial structure 130 is higher than the surface of the substrate 102.

As described above, in order to solve the aforementioned dilemma, the preferred embodiment provides an undoped cap layer 140 disposed on the epitaxial structure 130. It should be noted that, in the preferred embodiment, the undoped cap layer 140 is a composite film layer as shown in FIG. 3, and the undoped cap layer 140 includes at least a first single layer 140a and a second sheet. Layer 140b and a third single layer 140c. As shown in FIG. 3, the first single layer 140a and the third single layer 140c are formed between the second single layer 140b and the epitaxial structure 130, and the third single layer 140c is formed on the first single layer 140a. Between the second single layer 140b. The undoped cap layer 140 (including the first single layer 140a, the second single layer 140b, and the third single layer 140c) also includes the first semiconductor material and the second semiconductor material described above, that is, including germanium. The crucible in the first single layer 140a has a first concentration, the crucible in the second monolayer 140b has a second concentration, and the crucible in the third monolayer 140c has a third concentration, and the first concentration, the second concentration The concentration and the third concentration are both lower than the concentration of the epitaxial structure 130. In the preferred embodiment, the first concentration is preferably 25%, the second concentration is preferably 0%, and the third concentration is between the first concentration and the second concentration. For example, the third concentration is preferably 10%, but is not limited thereto. In other words, the second preferred embodiment provides a composite cover layer 140 having a reduced concentration of germanium from bottom to top. In addition, the thickness of the undoped cap layer 140 in the preferred embodiment may be 150 angstroms, but is not limited thereto. It should be noted that in the preferred embodiment, the thickness of the first single layer 140a, the thickness of the second single layer 140b, and the thickness of the third single layer 140c have a ratio, and the ratio is approximately equal to 1:1:1. .

As described above, the semiconductor device 100 provided by the preferred embodiment further includes an undoped underlayer 150. The features of the undoped underlayer 150 will be described in detail in the subsequent embodiments, and thus are not described herein.

According to the semiconductor device 100 having an epitaxial structure according to the third preferred embodiment, the surface of the epitaxial structure 130 is formed with a cover layer 140 of a composite film layer. The composite cover layer 140 includes a first single layer 140a, a third single layer 140c, and a second single layer 140b from bottom to top. The first single layer 140a, the third single layer 140c, and the second single layer 140b all include a defect. The concentration of germanium in the first single layer 140a is preferably 25%, the concentration of germanium in the third single layer 140c is preferably 10%, and the concentration of germanium in the second single layer 140b is preferably 0%, and the first single layer 140a The thickness of the third single layer 140c and the second single layer 140b are approximately equal. That is to say, the composite cover layer 140 is a composite film layer whose concentration is decreased from bottom to top. Since the germanium concentrations of the first single layer 140a and the third single layer 140c of the cap layer 140 are 25% and 10%, respectively, the second single layer 140b having a germanium concentration of 0% and the epitaxial layer having a germanium concentration of 36% are disposed. The structure 130 is intermediate, so it can be used as a buffer layer in both. And because the second single layer 140b and the epitaxial structure 130 have two layers of decreasing concentration, the concentration gradient difference is more gentle, so the composite cover layer 140 formed on the surface of the epitaxial structure 130 can obtain a flat surface. . The surface of the composite cover layer 140 is detected by AFM, and the root mean square surface roughness of the composite cover layer 140 is about 0.65 nm, which is compared with the root mean square surface roughness (4.21 nm) of the pure tantalum cover layer. Roughness achieved an unexpected improvement. In addition, since the germanium concentration in the second single layer 140b of the composite cover layer 140 is 0%, the second single layer 140b can be used as a reaction site for the metal telluride process, and the metal and the metal telluride process can be fundamentally avoided. The problem of agglomeration is formed.

Next, please refer to FIG. 4 to FIG. 5 , which are schematic diagrams showing fourth to fifth preferred embodiments of the semiconductor device having an epitaxial structure according to the present invention. It should be noted that in the fourth and fifth preferred embodiments, the same components as the first preferred embodiment, such as the substrate 102, the gate structure 110, the LDD 118, the sidewall spacers 120, the recesses 122, and the recesses are formed in the recesses. The epitaxial structure 130 within 122 is illustrated by the same reference numerals. The components included in the semiconductor device provided in the fourth and fifth preferred embodiments are the same as those in the foregoing preferred embodiment, and thus are not described herein again, but only the preferred embodiment and the foregoing embodiment are described. the difference.

As shown in FIG. 4, the fourth preferred embodiment forms an undoped underlayer 150 in the recess 122, that is, in the first to third preferred embodiments and the first to third embodiments. The undoped underlayer 150 is depicted. The undoped underlayer 150 is disposed between the epitaxial structure 130 and the substrate 102, and the undoped underlayer 150 covers the sidewalls and the bottom of the recess 122. As previously mentioned, the undoped underlayer 150 also includes a first semiconductor material and a second semiconductor material, ie, comprising germanium. The undoped underlayer 150 provided in the preferred embodiment is a single film layer, in order to avoid the problem that the starting lattice voltage of the epitaxial structure 130 and the substrate 102 are too large to cause a sudden drop in the starting voltage of the device. The concentration of germanium in the single underlayer 150 is less than the germanium concentration of the epitaxial structure 130, for example, may be approximately equal to 25%.

It is also worth noting that since the undoped underlayer 150 is disposed to avoid the problem caused by the excessive lattice constant difference between the epitaxial structure 130 and the substrate 102, the undoped underlayer 150 covering the bottom of the recess 122 is covered. The thickness should not be too thick, and occupy the space that the strain enthalpy (ie, the epitaxial structure 130) can form, thereby reducing the strain 矽 providing stress to the channel region. Therefore, in the preferred embodiment, the thickness of the undoped underlayer 150 covering the sidewalls of the recess 122 has a ratio to the thickness of the undoped underlayer 150 covering the bottom of the recess 122, and the ratio is approximately equal to 1:1. At the same germanium concentration, when a single bottom layer 150 is formed at a pressure of 50 Torr, the thickness of the single bottom layer 150 covering the sidewalls of the recess 122 and the thickness of the single bottom layer 150 covering the bottom of the recess 122 are approximately 1:2, resulting in a reduction in the space in which the epitaxial structure 130 can be formed. Therefore, in the preferred embodiment, a single underlayer 150 is formed under a pressure of 10 Torr, and a thickness of a single underlayer 150 covering a sidewall of the recess 122 and a thickness of a single underlayer 150 covering the bottom of the recess 122 are obtained. The ideal result of nearly 1:1.

According to the semiconductor device 100 having an epitaxial structure according to the fourth preferred embodiment, an undoped underlayer 150 having a single film layer is formed between the epitaxial structure 130 and the substrate 102. The undoped underlayer 150 contains ruthenium and the ruthenium concentration is preferably 25%. Since the undoped underlayer 150 has a germanium concentration of 25% and is disposed between the epitaxial structure 130 having a germanium concentration of 36% and the substrate 102 having a germanium concentration of 0%, the undoped underlayer 150 can be used as one of the two. The buffer layer avoids the problem that the starting voltage of the element suddenly drops due to the difference in the lattice constant of the junction between the epitaxial structure 130 and the substrate 102. In addition, the single bottom layer 150 provided by the preferred embodiment has the feature that the ratio of the thickness of the sidewall of the recess 122 to the thickness of the bottom of the recess 122 is 1:1, so that the single underlayer 150 does not occupy the epitaxial layer. The valuable space of structure 130. That is to say, the single bottom layer 150 provided by the preferred embodiment can effectively improve the problem that the starting voltage of the component suddenly drops without affecting the stress.

Next, please refer to FIG. 5. FIG. 5 is a schematic view showing a fifth preferred embodiment of the semiconductor device having an epitaxial structure according to the present invention. As shown in FIG. 5, the fifth preferred embodiment forms an undoped underlayer 150 in the recess 122, that is, in the first to third preferred embodiments and the first to third embodiments. The undoped underlayer 150 is depicted. The undoped underlayer 150 is disposed between the epitaxial structure 130 and the substrate 102, and the undoped underlayer 150 covers the sidewalls and the bottom of the recess 122. As previously mentioned, the undoped underlayer 150 also includes a first semiconductor material and a second semiconductor material, ie, comprising germanium. It should be noted that the undoped underlayer 150 provided in the preferred embodiment is a composite underlayer comprising a first single layer 150a, a second single layer 150b and a third single from bottom to top. Layer 150c. The crucible in the first single layer 150a has a first concentration, the crucible in the second monolayer 150b has a second concentration, and the crucible in the third monolayer 150c has a third concentration, the first concentration and the second concentration. And the third concentration is lower than the germanium concentration of the epitaxial structure 130, and the third concentration is greater than the second concentration, and the second concentration is greater than the first concentration. For example, the first concentration is 10%, the second concentration is 17%, and the third concentration is 25%. In other words, the preferred embodiment provides a composite underlayer 150 having a germanium concentration increasing from bottom to top. In addition, the first single layer 150a, the second single layer 150b, and the thickness of the third single layer 150c have a ratio, and the ratio is between 1:1:1 and 1:1:2. It should be noted that as the ratio of the thicknesses of the first single layer 150a, the second single layer 150b, and the third single layer 150c increases, the thickness of the composite bottom layer 150 covering the sidewalls of the recess 122 and the bottom of the covering recess 122 are combined. The ratio of the thickness of the bottom layer 150 is closer to 1:1.

According to the semiconductor device 100 having an epitaxial structure according to the fifth preferred embodiment, an undoped underlayer 150 of a composite film layer is formed between the epitaxial structure 130 and the substrate 102. The composite underlayer 150 includes a first single layer 150a, a second single layer 150b, and a third single layer 150c, and the first single layer 150a, the second single layer 150b, and the third single layer 150c all contain germanium. Since the germanium concentrations of the first single layer 150a, the second single layer 150b, and the third single layer 150c of the composite underlayer 150 are increased from 10% to 17% and then increased to 25%, respectively, the germanium concentration is set to 0%. The composite underlayer 150 between the substrate 102 and the epitaxial structure 130 having a germanium concentration of 36% can serve as a buffer layer in both. Moreover, since the composite underlayer 150 is a composite film layer with increasing concentration, the difference in concentration gradient between the substrate 102 and the epitaxial structure 130 can be made more gentle, and the difference in lattice constant between the epitaxial structure 130 and the substrate 102 can be avoided. The composite underlayer 150 provided in the preferred embodiment has the feature that the thickness of the sidewall of the recess 122 and the thickness of the bottom of the recess 122 are closer to 1:1. Therefore, the composite underlayer 150 does not occupy the valuable space for forming the epitaxial structure 130. That is to say, the composite underlayer 150 provided by the preferred embodiment can more effectively improve the problem that the starting voltage of the component suddenly drops without affecting the stress.

In addition, it should be noted that the fourth to fifth preferred embodiments provided by the present invention can be combined with the first to third preferred embodiments described above, so that the semiconductor device 100 having the epitaxial structure 130 is obtained the most. Excellent electrical performance is the goal.

In summary, according to the semiconductor device having an epitaxial structure provided by the present invention, the surface of the epitaxial structure is formed with an undoped cap layer having a lower germanium concentration, thereby avoiding metal thinning in the metal germanide process. The problem of agglomeration with the tantalum in the epitaxial layer, thereby causing leakage of the junction. In addition, the epitaxial semiconductor device provided by the present invention is provided with a lower concentration of undoped underlayer between the epitaxial structure in the recess and the substrate to avoid the connection between the epitaxial layer and the germanium substrate. The difference in the lattice arrangement of the face is too large, which in turn causes a sudden drop in the starting voltage of the component.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

100. . . Semiconductor component

102. . . Base

110. . . Gate structure

112. . . Gate insulation

114. . . Gate electrode

116. . . Patterned hard mask

118. . . Lightly doped bungee

120. . . Side wall

122. . . Groove

130. . . Epitaxial structure

140. . . Undoped cover

140a. . . First single layer

140b. . . Second single layer

140c. . . Third single layer

150. . . Undoped bottom layer

150a. . . First single layer

150b. . . Second single layer

150c. . . Third single layer

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view showing a first preferred embodiment of a semiconductor device having an epitaxial structure according to the present invention.

2 is a schematic view showing a second preferred embodiment of a semiconductor element having an epitaxial structure provided by the present invention.

Figure 3 is a schematic view showing a third preferred embodiment of a semiconductor device having an epitaxial structure provided by the present invention.

Figure 4 is a schematic view showing a fourth preferred embodiment of a semiconductor device having an epitaxial structure provided by the present invention.

Figure 5 is a schematic view showing a fifth preferred embodiment of a semiconductor device having an epitaxial structure provided by the present invention.

100. . . Semiconductor component

102. . . Base

110. . . Gate structure

112. . . Gate insulation

114. . . Gate electrode

116. . . Patterned hard mask

118. . . Lightly doped bungee

120. . . Side wall

122. . . Groove

130. . . Epitaxial structure

140. . . Undoped cover

140a. . . First single layer

140b. . . Second single layer

150. . . Undoped bottom layer

Claims (26)

A semiconductor device having an epitaxial source/drainage, comprising: a gate structure disposed on a substrate; an epitaxial structure disposed in the substrate on both sides of the gate structure, the epitaxial structure comprising a doped material, a first semiconductor material and a second semiconductor material, the first semiconductor material having a first lattice constant, the second semiconductor material having a second lattice constant, and the second lattice constant being greater than The first lattice constant, the second semiconductor material has a first concentration in the epitaxial structure; and an undoped cap layer disposed on the epitaxial structure, the undoped cap layer comprising the first semiconductor The material and the second semiconductor material, the second semiconductor material in the undoped cap layer has at least a second concentration, the second concentration is less than the first concentration, and the second concentration is at least 25%. The semiconductor device of claim 1, further comprising: a lightly doped drain disposed in the substrate on both sides of the gate structure; and a sidewall disposed on a sidewall of the gate structure. The semiconductor component of claim 1, wherein the first semiconductor material comprises germanium and the second semiconductor material comprises germanium. The semiconductor component of claim 1, wherein the second concentration is equal to 25%. The semiconductor device of claim 1, wherein the undoped cap layer comprises a single film layer or a composite film layer. The semiconductor device of claim 5, wherein the composite film layer comprises at least a first single layer and a second single layer, the first single layer being formed on the second single layer and the epitaxial structure The first monolayer has the second concentration, the second semiconductor material in the second monolayer has a third concentration, and the third concentration is equal to 0%. The semiconductor device of claim 6, wherein the first single layer has a ratio to the thickness of the second single layer, and the ratio is equal to 1:2. The semiconductor device of claim 6, wherein the composite film layer further comprises a third single layer disposed between the first single layer and the second single layer, wherein the third single layer The second semiconductor material has a fourth concentration, and the fourth concentration is between the second concentration and the third concentration. The semiconductor component of claim 8, wherein the fourth concentration is approximately equal to 10%. The semiconductor device of claim 8, wherein the first single layer, the second single layer and the third single layer have a ratio of a thickness, and the ratio is equal to 1:1:1. The semiconductor component according to claim 1, further comprising a composite underlayer, And disposed between the epitaxial structure and the substrate, and the composite underlayer includes the first semiconductor material and the second semiconductor material. The semiconductor device of claim 11, wherein the concentration of the second semiconductor material in the composite underlayer is between 10 and 25%. The semiconductor device of claim 12, wherein the concentration of the second semiconductor material in the composite underlayer is increased from bottom to top. A semiconductor device having an epitaxial structure, comprising: a gate structure disposed on a substrate; a pair of grooves disposed in the substrate on both sides of the gate structure; an epitaxial structure disposed on the substrate In the recess on both sides of the gate structure, the epitaxial structure comprises a doping material, a first semiconductor material and a second semiconductor material, the first semiconductor material having a first lattice constant, the second semiconductor The material has a second lattice constant, and the second lattice constant is greater than the first lattice constant, wherein the second semiconductor material has a first concentration in the epitaxial structure; an undoped underlayer is formed in the concave In the trench, and disposed between the epitaxial structure and the substrate, the undoped underlayer covers the sidewall of the recess and the bottom of the recess, and includes the first semiconductor material and the second semiconductor material, The second semiconductor material in the undoped underlayer has at least a second concentration, and the second concentration is less than the first concentration; and an undoped cap layer disposed on the epitaxial structure, the undoped cap layer Including a first semiconductor material and the second semiconductor material, wherein one of the second semiconductor materials in the undoped cap layer has a concentration of at least 25%. The semiconductor device of claim 14, further comprising: a lightly doped drain disposed in the substrate on both sides of the gate structure; and a sidewall disposed on a sidewall of the gate structure. The semiconductor component of claim 14, wherein the first semiconductor material comprises germanium and the second semiconductor material comprises germanium. The semiconductor component of claim 14, wherein the second concentration is equal to 25%. The semiconductor device of claim 14, wherein a thickness of the undoped underlayer covering the sidewall of the recess has a ratio to a thickness of the undoped underlayer covering the bottom of the recess, and the ratio is approximately equal to 1:1. The semiconductor component of claim 18, wherein the undoped underlayer comprises a single underlayer or a composite underlayer. The semiconductor device according to claim 19, wherein the composite underlayer comprises at least a first single layer, a second single layer and a third single layer, which are sequentially formed on the sidewall of the groove from bottom to top. The bottom of the groove. The semiconductor device of claim 20, wherein the third single layer has the second concentration, the second single layer has a third concentration, and the first single layer has a fourth concentration, the second The concentration system is greater than the third concentration, and the third concentration is greater than the fourth concentration. The semiconductor device according to claim 21, wherein the third concentration is 17% and the fourth concentration is 10%. The semiconductor device according to claim 21, wherein the first single layer, the second single layer and the third single layer have a thickness ratio of 1:1:1 and 1:1:2. The semiconductor device of claim 14, further comprising a composite cover layer disposed on the epitaxial structure, wherein the composite cover layer comprises the first semiconductor material and the second semiconductor material. The semiconductor device according to claim 24, wherein the concentration of the second semiconductor material in the composite coating layer is between 0 and 25%. The semiconductor device of claim 25, wherein the concentration of the second semiconductor material in the composite cover layer decreases from bottom to top.