Semiconductor Device

Abstract

To provide a semiconductor device capable of detecting a positional deviation of an impurity formation region defined by a position where an ion implantation region is formed.SOLUTION: In a semiconductor device having a unit monitor element, the unit monitor element includes a resistor region made of polysilicon, a second conductivity type high-concentration region made of polysilicon provided at both ends of the resistor region in a first direction, a pair of second conductivity type impurity diffusion regions formed in contact with the high-concentration region and spaced apart from each other, and an ion-implanted region provided outside the resistor region and formed of a connecting region that connects the pair of impurity diffusion regions and, and when mutual positions in a second direction between the ion-implanted region and the resistor region deviate by a reference amount or more, a connection portion is formed in the resistor region to connect the pair of impurity diffusion regions, and presence or absence of deviation of the ion-implanted region with respect to the resistor region can be determined on the basis of the electrical characteristic measurement result of the unit monitor element.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a semiconductor device capable of detecting misalignment during an ion implantation process using a resist as a mask in a semiconductor wafer manufacturing process. [Background technology]

[0002] The ion implantation process, in which ions accelerated by an electric field are implanted into the surface of a semiconductor substrate made of silicon or the like on which a resist pattern has been formed, thereby forming impurity diffusion regions at predetermined locations, is an indispensable technology in the wafer manufacturing process, which is also known as the front-end process for manufacturing semiconductor devices.

[0003] Whether or not a pattern has been formed using a resist is confirmed by optical means using alignment marks during the wafer manufacturing process, but it is difficult to detect in situ whether or not an impurity diffusion region in which impurity ions have been diffused by ion implantation has been formed correctly.

[0004] Therefore, as shown in Patent Document 1, it is possible to indirectly infer that there was a defect in the formation of an impurity diffusion region by ion implantation due to a change in the electrical characteristics of an element contained in a finished semiconductor product, or to directly confirm the presence of impurity atoms that should not be there by using a spectroscopic technique such as X-ray photoelectron spectroscopy (XPS), thereby later learning that an impurity diffusion region in which impurity ions are diffused was not formed correctly during the ion implantation process. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2008-198634 A Summary of the Invention [Problem to be solved by the invention]

[0006] The semiconductor device shown in Patent Document 1 identifies the amount of misalignment between two types of impurity diffusion regions with different conductivity types formed by ion implantation by comparing the resistance values ​​of multiple unit monitor elements. However, the individual resistance values ​​of the resistor-shaped unit monitor elements vary due to various factors, making it difficult to directly determine the presence or absence of an abnormality from the resistance values ​​of multiple unit monitor elements associated with a single semiconductor device, i.e., a single IC. Accumulated data is required for such a determination.

[0007] Therefore, an object of the present invention is to provide a semiconductor device having an alignment evaluation element that can identify whether or not there is an overlap between an impurity diffusion region formed by ion implantation and a polysilicon resistor by alternatively determining whether or not a current flows through a unit monitor element. [Means for solving the problem]

[0008] In order to solve the above problems, a semiconductor according to one embodiment of the present invention has the following configuration. 1. A semiconductor device comprising: an alignment evaluation element formed on a semiconductor substrate, the alignment evaluation element evaluating the quality of alignment between an impurity diffusion region formed by implanting impurity ions into the semiconductor substrate and a resistance element made of polysilicon, the semiconductor device comprising: the alignment evaluation element has a unit monitor element, Each of the unit monitor elements includes a resistance region made of polysilicon having a rectangular shape, a set of high concentration regions of a second conductivity type made of polysilicon provided in contact with both ends of the resistance region in a first direction, a set of impurity diffusion regions of the second conductivity type formed on a surface of the resistance region in contact with the high concentration regions and spaced apart from each other in the first direction, and an ion implantation region including the set of impurity diffusion regions and provided outside the resistance region, the ion implantation region including a connection region connecting the set of impurity diffusion regions, when a relative position between the ion implantation region and the resistance region in a second direction perpendicular to the first direction is shifted by a reference amount or more, a connection portion that connects the pair of impurity diffusion regions to each other is formed in the resistance region; The semiconductor device is capable of identifying the presence or absence of a deviation of the ion implantation region from the resistance region based on the electrical characteristic measurement result for the resistance region from the unit monitor element.

[0009] A semiconductor according to another embodiment of the present invention has the following configuration. 1. A semiconductor device comprising: an alignment evaluation element formed on a semiconductor substrate, the alignment evaluation element evaluating the quality of alignment between an impurity diffusion region formed by implanting impurity ions into the semiconductor substrate and a resistance element made of polysilicon, the semiconductor device comprising: the alignment evaluation element has a unit monitor element, Each of the unit monitor elements includes a resistance region made of polysilicon having a rectangular shape, a set of high concentration regions of a second conductivity type made of polysilicon provided in contact with both ends of the resistance region in a first direction, a set of impurity diffusion regions of the second conductivity type formed on a surface of the resistance region in contact with the high concentration regions and spaced apart from each other in the first direction, and an ion implantation region including the set of impurity diffusion regions and covering a part of the surface of the resistance region along one side of the resistance region, the ion implantation region including the set of impurity diffusion regions and including a connection region connecting the set of impurity diffusion regions, when a relative position between the ion implantation region and the resistance region in a second direction perpendicular to the first direction is shifted by a reference amount or more, a connection portion connecting the pair of impurity diffusion regions to each other is removed in the resistance region; The semiconductor device is capable of identifying the presence or absence of a deviation of the ion implantation region from the resistance region based on the electrical characteristic measurement result for the resistance region from the unit monitor element. Effect of the Invention

[0010] It is possible to provide a semiconductor device having an alignment evaluation element made of a basic minitor element capable of detecting with high accuracy the positional deviation of an impurity formation region defined by the position where an ion implantation region is formed, and therefore it is possible to provide a semiconductor device with little variation in quality. [Brief description of the drawings]

[0011] [Figure 1] 1A and 1B are schematic top views of a unit monitor element constituting an alignment evaluation element included in a semiconductor device according to a first embodiment of the present invention, where (a) shows a case where an ion-implanted region to be evaluated is normally formed, and (b) shows a case where the ion-implanted region is misaligned. [Diagram 2] 2 is a schematic cross-sectional view taken along the cutting line of the unit monitor element shown in Fig. 1. (a) shows a case where the ion-implanted region to be evaluated was formed normally, and (b) shows a case where the ion-implanted region was formed misaligned. [Diagram 3] This is a diagram showing the positional relationship between the polysilicon resistance region and the ion implantation region in the unit monitor element shown in Figure 1. (a) shows the case where the ion implantation region to be evaluated is normally positioned, and (b) shows the case where the ion implantation region is misaligned. [Figure 4] FIG. 2 is a diagram showing the positional relationship between a polysilicon resistance region and an ion implantation region in an alignment evaluation element using a plurality of unit monitor elements according to the first embodiment of the present invention. [Diagram 5] FIG. 4 is a diagram showing a modified example of the semiconductor device according to the first embodiment of the present invention. [Figure 6] 4 is a diagram showing an example of the arrangement of photoresists for forming ion implantation regions of the unit monitor element shown in FIG. 3. FIG. [Figure 7] 13 is a diagram for explaining a gap provided between a polysilicon resistance region and an ion implantation region. FIG. [Figure 8] 1A and 1B are schematic top views of a unit monitor element constituting an alignment evaluation element included in a semiconductor device according to a second embodiment of the present invention, where (a) shows a case where an ion-implanted region to be evaluated is normally formed, and (b) shows a case where the ion-implanted region is misaligned. [Figure 9] This is a diagram showing the positional relationship between the polysilicon resistance region and the ion implantation region in the unit monitor element shown in Fig. 8. (a) shows the case where the ion implantation region to be evaluated is normally positioned, and (b) shows the case where the ion implantation region is misaligned. [Figure 10]FIG. 11 is a diagram showing the positional relationship between a polysilicon resistance region and an ion implantation region in an alignment evaluation element using a plurality of unit monitor elements according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 is a schematic top view of a unit monitor element constituting an alignment evaluation element included in a semiconductor device according to a first embodiment of the present invention, where (a) shows a case where an ion-implanted region to be evaluated is formed normally, and (b) shows a case where the ion-implanted region is formed misaligned.

[0013] As shown in Fig. 1(a), the unit monitor element 100 has, as its basic shape, a rectangular resistance region 1 made of a first conductivity type or non-doped polysilicon containing no impurities, and a set of high concentration regions 2 (2A, 2B) of a second conductivity type made of similarly rectangular polysilicon provided in contact with both ends of the resistance region 1. The direction connecting the set of high concentration regions 2 (2A, 2B) of the second conductivity type is referred to as the first direction. Therefore, the resistance region 1 has two sides that are not in contact with the high concentration regions 2 (2A, 2B) that face each other at a distance, except for the two ends, and these two sides are parallel to the first direction. If the first conductivity type is N-type, the second conductivity type is P-type, and conversely, if the first conductivity type is P-type, the second conductivity type is N-type.

[0014] The unit monitoring element 100 has a pair of impurity diffusion regions 8 of a second conductivity type formed on the surface of the resistance region 1 between the resistance region 1 and a pair of second conductivity type high concentration regions 2 (2A, 2B) at both ends, in contact with the high concentration regions 2 (2A, 2B) and spaced apart from each other in the first direction. The unit monitoring element 100 further has measurement terminals 4 (4A, 4B) made of conductors connected to the high concentration regions 2 (2A, 2B) via contacts 5 (5A, 5B) above the high concentration regions 2 (2A, 2B). A plurality of insulating films, such as intermediate insulating films and interlayer insulating films, are usually stacked between the high concentration regions 2 (2A, 2B) and the measurement terminals 4 (4A, 4B). The unit monitor element 100 shows a case where the impurity diffusion regions 8 are formed only on both ends of the resistance region 1, and ion implantation of the second conductivity type impurity to form the impurity diffusion regions 8 is performed normally. The impurity diffusion regions 8 are formed as part of an ion implantation region of the second conductivity type impurity, which will be described later. In order to form the second conductivity type impurity diffusion regions 8 at both ends of the resistance region 1, it is necessary to set the impurity concentration of the resistance region 1 lower than the impurity concentration of the second conductivity type impurity diffusion regions 8 formed by ion implantation, or to make the resistance region 1 of non-doped polysilicon that does not contain impurities.

[0015] FIG. 1(b) also shows a unit monitoring element 110, illustrating a case where the ion implantation to form the impurity diffusion region 8 was not performed normally. The unit monitoring element 110 differs from the unit monitoring element 100 shown in FIG. 1(a) in that a connection portion 9 that interconnects a set of impurity diffusion regions 8 is disposed along a side in the first direction of the resistance region 1. The connection portion 9 is a region formed by ion implantation of a second conductivity type impurity, just like the set of impurity diffusion regions 8. The other components are the same, so a description thereof will be omitted.

[0016] FIG. 2 is a schematic cross-sectional view taken along the cutting lines depicted on unit monitor elements 100 and 110 shown in FIG.

[0017] FIG. 2(a) is a schematic cross-sectional view of the unit monitor element 100 cut along the cutting line AA, showing a case where the ion-implanted region to be evaluated is formed normally. The unit monitor element 100 is generally disposed on the surface of a field oxide film 30 provided on a semiconductor substrate 20. The field oxide film may be a LOCS oxide film. When the ion-implanted region to be evaluated is formed normally, the second-conductivity-type impurity diffusion regions 8 are formed at both ends of the resistance region 1, spaced apart from each other. The second-conductivity-type impurity diffusion regions 8 are not necessarily formed over the entire depth direction of the resistance region 1, from the front surface to the back surface. The second-conductivity-type impurity diffusion regions 8 may be formed over the entire depth direction of the resistance region 1, depending on the conditions of ion implantation for forming the conductivity-type impurity diffusion regions 8.

[0018] As described above, in unit monitoring element 100, second conductivity type high concentration regions 2 (2A, 2B) located at both ends of resistance region 1 made of first conductivity type or undoped polysilicon containing no impurities are not electrically connected to each other by impurity diffusion region 8 also of the second conductivity type. Therefore, even if a voltage is applied from measurement terminals 4 (4A, 4B) between second conductivity type high concentration regions 2 (2A, 2B) at both ends of unit monitoring element 100, no current will flow across resistance region 1 that is undoped or has a different conductivity type.

[0019] FIG. 2(b) is a schematic cross-sectional view of the unit monitoring element 110 cut along the cutting line BB, showing a case where the ion-implanted region to be evaluated was not formed normally. Since the cutting line BB is drawn along the connection portion 9, in the schematic cross-sectional view of FIG. 2(b), the second-conductivity-type high-concentration regions 2 (2A, 2B) located at both ends of the resistance region 1 of the unit monitoring element 110 are connected by the second-conductivity-type connection portion 9 formed to a certain depth from the surface of the resistance region 1. Since the high-concentration regions 2 (2A, 2B) and the connection portion 9 are both of the second conductivity type, when a voltage is applied from the measurement terminals 4 (4A, 4B) between the second-conductivity-type high-concentration regions 2 (2A, 2B) at both ends of the unit monitoring element 110, a current flows across the resistance region 1. The connection portion 9 may be formed over the entire depth direction of the resistance region 1 depending on the conditions of ion implantation for forming the second-conductivity-type impurity diffusion region 8. As described above, the unit monitor element 100 has a shape similar to a resistive element made of polysilicon provided within a semiconductor device, and by applying a voltage between the measurement terminals 4 (4A, 4B) and alternatively determining whether or not a current flows, it is possible to detect the presence or absence of an actual effect of impurity ions introduced in the ion implantation process that may affect the resistive element.

[0020] Next, the reason why a connection part 9 is formed along one side of the resistance region 1 due to a misalignment when forming the ion implantation region to be evaluated will be explained using Fig. 3. Fig. 3 is a diagram showing the positional relationship between the polysilicon resistance region and the ion implantation region in the unit monitor element shown in Fig. 1. (a) shows the case where the ion implantation region to be evaluated is positioned correctly, and (b) shows the case where the ion implantation region is positioned misaligned.

[0021] 3(a) shows a unit monitor element 300 in which an ion implantation region 10 (10A) for forming a second conductivity type impurity diffusion region 8 is normally arranged in a region inside the second conductivity type high concentration regions 2 (2A, 2B) at both ends of a resistance region 1 having a second conductivity type high concentration regions 2 (2A, 2B) at both ends. The ion implantation region 10 (10A) has two regions into which ions are implanted to form a pair of second conductivity type impurity diffusion regions 8 arranged at a distance from each other on the surface of the resistance region 1, and a connection region 11 connecting these two regions to each other.

[0022] The two regions into which ions are implanted to form the impurity diffusion region 8 are not only provided on the impurity diffusion region 8 to be formed, but also cover a part of the high concentration region 2 (2A, 2B) of the second conductivity type and extend on the field oxide film 30. The connection region 11 is provided so that a gap 12 having a predetermined size is formed between the connection region 1 and the resistance region 1 along the first direction. In this state, the connection region 11 is provided only on the field oxide film 30. Only the part of the ion implantation region 10 (10A) provided on the resistance region 1 affects the electrical characteristics of the unit monitor element 100. Since the concentration of impurity ions in the ion implantation region 10 (10A) is lower than the impurity concentration in the high concentration region 2 (2A, 2B), the ion implantation region 10 (10A) does not affect the high concentration region 2 (2A, 2B). The ion implantation region 10 (10A) provided on the field oxide film 30 does not affect the field oxide film 30, and does not affect the unit monitor element 300.

[0023] Here, the case where the ion implantation region 10 (10A) is normally arranged refers to a state where the ion implantation region 10 (10A) is formed with a gap 12 of a predetermined size between it and the resistance region 1. When the ion implantation region 10 (10A) is normally arranged, a pair of second conductivity type impurity diffusion regions 8 are simply formed in the resistance region 1 at a distance from each other in regions inside the second conductivity type high concentration regions 2 (2A, 2B) on both ends.

[0024] Next, a case where the ion implantation region 10 (10A) is not normal and is arranged out of alignment will be described with reference to FIG. 3(b). In FIG. 3(b), the ion implantation region 10 (10A) is arranged overlapping the resistance region 1. In the drawing, since the ion implantation region 10 (10A) is arranged out of alignment to the right, a gap 12 is not formed, and the connection region 11 of the ion implantation region 10 (10A) overlaps the resistance region 1. Therefore, the impurity ions are implanted along one side of the resistance region 1 in the first direction, and a connection portion 9 is formed between a pair of impurity diffusion regions 8. Therefore, the high concentration regions 2 (2A, 2B) of the second conductivity type at both ends, which should be electrically separated, are electrically connected. The predetermined size set for gap 12 is a size that prevents connection portion 9 from being formed on resistance region 1 even if connection region 11 of impurity diffusion region 8 is shifted by the maximum allowable amount in a second direction perpendicular to the first direction toward resistance region 1. In the following description, the second direction will also be referred to as the direction from the connection region toward the resistance region.

[0025] As described above, the unit monitoring element 100 can detect that the ion-implanted region 10 (10A) has shifted in the direction from the connecting region toward the resistance region so as to narrow the gap 12 formed between the ion-implanted region 10 (10A) and the resistance region 1, and that the ion-implanted region 10 (10A) has overlapped with the resistance region 1, by forming the connection portion 9. In terms of Figures 1 and 3, the unit monitoring element 100 can detect the shift of the ion-implanted region 10 (10A) to the right on the paper of Figures 1 and 3.

[0026] Next, a semiconductor device having an alignment evaluation element that is composed of a plurality of unit monitor elements and can detect deviations in four directions of an ion implantation region will be described.

[0027] FIG. 4 is a diagram showing the positional relationship between a polysilicon resistance region and an ion implantation region in an alignment evaluation element using a plurality of unit monitor elements according to the first embodiment of the present invention. The alignment evaluation element 400 is formed by independently arranging four unit monitor elements 300 shown in Fig. 3. The direction from the link region 11 toward the resistance region 1 in the ion implantation region 10 (10A, 10B, 10C, 10D) of each unit monitor element is different, and the elements are arranged in four directions, up, down, left, and right, parallel to the paper surface on which Fig. 4 is shown.

[0028] When arranged in this manner, a voltage is applied between the high concentration regions 2 at both ends of each unit monitoring element, and by determining whether or not a current flows, it becomes possible to detect the presence or absence of a deviation exceeding the maximum allowable value in any of the four directions of the ion implantation region 10. If there is a unit monitoring element through which a current flows between the high concentration regions 2, it is possible to detect the occurrence of a deviation in the direction from the connection region 11 of that unit monitoring element toward the resistance region 1. Incidentally, by connecting multiple unit monitor elements in parallel among the unit monitor elements included in the alignment evaluation element 400 shown in FIG. 4, it is possible to detect the presence or absence of a deviation exceeding the maximum allowable value in any of the directions that can be detected by the unit monitor elements connected in parallel with a single current measurement.

[0029] Fig. 5 is a diagram showing a modified example of a unit monitoring element included in alignment evaluation element 400 shown in Fig. 4. Unit monitoring elements 510 and 520 included in alignment evaluation element 500 shown in Fig. 5 have ion implantation regions 10 arranged so that gaps 12 are formed on both sides of the resistance region. In other words, they have the same function as two unit monitoring elements 300 connected in parallel. Unit monitoring element 510 can detect left-right deviation along the paper surface of Fig. 5, and unit monitoring element 520 can detect up-down deviation along the paper surface of Fig. 5.

[0030] Next, the relationship between the ion implantation region and the photoresist that determines the ion implantation region will be described with reference to FIGS.

[0031] 6 illustrates the shape of the photoresist that determines the ion implantation region 10 for forming the unit monitoring element 300 shown in FIG. 3, only depicting the periphery of the unit monitoring element. The patterned photoresist 3 covers the central portion of the resistance region 1 that constitutes the unit monitoring element 300, and protrudes slightly along one side of the resistance region 1, which is the left side in FIG. 6. This protruding portion essentially forms a gap 12. Both ends of the resistance region 1 and the portions of the high concentration regions 2 (2A, 2B) that are connected to the resistance region 1 are exposed from the photoresist 3, so that the impurity diffusion regions 8 formed by the ion-implanted impurities are in reliable contact with the high concentration regions 2 (2A, 2B).

[0032] 7 is a diagram for explaining the gap provided between the polysilicon resistance region and the ion implantation region. It shows a cross section taken along the cutting line CC in FIG. 6. The resistance region 1 is disposed on the surface of the field oxide film 30, and the patterned photoresist 3 covers the resistance region 1. The vertical thickness of the photoresist 3 disposed on the upper surface of the resistance region 1 is T1, and the horizontal thickness of the photoresist 3 in contact with the side surface of the resistance region 1 is X.

[0033] FIG. 7 shows the moment when impurity ions fly in along an implantation direction 7. In general, the implantation direction 7 along which the impurity ions fly is inclined at an angle θ with respect to the perpendicular line. This is to prevent channeling, in which the impurity ions are implanted deep along the gaps between crystals. In addition, since the ion implantation is performed while rotating the semiconductor substrate on which the semiconductor device having the alignment evaluation element is formed, the impurity ions fly in from various directions.

[0034] The ion implantation region 10 is basically determined by the region formed by the patterned photoresist 3. Therefore, the size of the gap 12 formed between the resistance region 1 and the ion implantation region 10 is basically determined by the horizontal thickness X of the photoresist 3 in contact with the side surface of the resistance region 1. However, as described above, the impurity ions fly at a certain angle θ and penetrate the photoresist 3 from the side surface. As a result, the size of the gap 12 formed by the absence of implantation of the impurity ions is smaller than the horizontal thickness X of the photoresist 3. The vertical thickness T1 of the photoresist 3 is set so that impurity ions do not pass through the photoresist 3 and reach the top surface of the resistance region 1. Therefore, it is thought that impurity ions will not penetrate if the thickness X of the photoresist 3 in contact with the side of the resistance region 1 is about T1 tan θ.

[0035] Furthermore, the size of the gap 12 may vary due to the misalignment of the photoresist. If the variation is within an allowable range, a maximum allowable value is set so that patterning can be performed without any problems. If the maximum allowable value is set to 3σ, then if the thickness X of the photoresist 3 in contact with the side surface of the resistance region 1 is set to, for example, 3σ+T1·tanθ, then as long as the misalignment of the photoresist is within the allowable range, the impurity ions will not reach the resistance region 1, and the connection 9 will not be formed between a pair of impurity diffusion regions 8. On the other hand, if the misalignment of the photoresist in the direction of reducing the thickness X of the photoresist 3 exceeds 3σ, the impurity ions will reach the resistance region 1 and form the connection 9 between a pair of impurity diffusion regions 8. By setting as above, it becomes possible for the unit monitor element to detect a deviation in the direction from the link region 11 toward the resistance region 1 that is equal to or greater than the maximum allowable value.

[0036] As described above, in the first embodiment, a configuration of a unit monitor element was described in which no current flows between the measurement terminals when an ion implantation region to be evaluated is normally arranged and formed in polysilicon, and a current flows between the measurement terminals when the ion implantation region is not normally arranged and formed with a large deviation. Next, as a second embodiment, a unit monitor element having a configuration in which a current flows between the measurement terminals when an ion implantation region to be evaluated is normally arranged and formed in polysilicon, and a current does not flow between the measurement terminals when the ion implantation region is not normally arranged and formed with a large deviation will be described. 8 is a schematic top view of a unit monitor element constituting an alignment evaluation element included in a semiconductor device according to a second embodiment of the present invention, where (a) shows a case where the ion implantation region to be evaluated is formed normally, and (b) shows a case where the ion implantation region is formed misaligned.

[0037] The unit monitoring element 800 shown in FIG. 8(a) has the same configuration as the unit monitoring element 110 shown in FIG. 1. The unit monitoring element 800 has a rectangular resistance region 1 made of a first conductivity type or non-doped polysilicon containing no impurities, and a pair of second conductivity type high concentration regions 2 (2A, 2B) made of similarly rectangular polysilicon provided in contact with both ends of the resistance region 1. The direction connecting the pair of second conductivity type high concentration regions 2 (2A, 2B) is referred to as a first direction. The resistance region 1 has two sides that are not in contact with the high concentration regions 2 (2A, 2B) that face each other at a distance, except for both ends, and these two sides are parallel to the first direction. If the first conductivity type is N-type, the second conductivity type is P-type, and conversely, if the first conductivity type is P-type, the second conductivity type is N-type.

[0038] The unit monitoring element 800 has a set of impurity diffusion regions 8 of a second conductivity type formed on the surface of the resistance region 1 between the resistance region 1 and a set of second conductivity type high concentration regions 2 (2A, 2B) at both ends, in contact with the high concentration regions 2 (2A, 2B) and spaced apart from each other in the first direction. Furthermore, a connection portion 9 connecting the set of impurity diffusion regions 8 to each other is arranged along a side of the resistance region 1 in the first direction. The unit monitoring element 800 also has measurement terminals 4 (4A, 4B) made of conductors connected to the high concentration regions 2 (2A, 2B) via contacts 5 (5A, 5B). The unit monitor element 800 shows a case where ion implantation of a second conductivity type impurity is performed normally to form the impurity diffusion region 8. The impurity diffusion region 8 is formed as a part of an ion implantation region of a second conductivity type impurity, which will be described later. In order to form the second conductivity type impurity diffusion regions 8 and the second conductivity type connection portions 9 at both ends of the resistance region 1, it is necessary to set the impurity concentration of the resistance region 1 lower than the impurity concentration of the second conductivity type impurity diffusion region 8 formed by ion implantation, or to make the resistance region 1 of non-doped polysilicon that does not contain impurities.

[0039] Figure 8(b) also shows a unit monitor element 810, illustrating a case where the ion implantation to form the impurity diffusion regions 8 was not performed normally. The unit monitor element 810 differs from the unit monitor element 700 shown in Figure 8(a) in that it does not have a connection part 9 that interconnects a set of impurity diffusion regions 8. The other components are the same, so a description thereof will be omitted.

[0040] If the unit monitoring element is formed normally, when a voltage is applied from measurement terminals 4 (4A, 4B) between the second conductivity type high concentration regions 2 (2A, 2B) at both ends of unit monitoring element 800, a current will flow across resistance region 1; if the unit monitoring element is not formed normally, even if a voltage is applied from measurement terminals 4 (4A, 4B) between the second conductivity type high concentration regions 2 (2A, 2B) at both ends of unit monitoring element 810, no current will flow through resistance region 1. As described above, the unit monitor element 800 has a shape similar to a resistive element made of polysilicon provided in a semiconductor device, and by applying a voltage between the measurement terminals 4 (4A, 4B) and alternatively determining whether or not a current flows, it is possible to detect whether or not there is an actual effect of impurity ions introduced in the ion implantation process that may affect the resistive element.

[0041] Next, the reason why a connection portion 9 is not formed along one side of the resistance region 1 due to a misalignment when forming the ion implantation region to be evaluated will be explained using Fig. 9. Fig. 9 is a diagram showing the positional relationship between the polysilicon resistance region and the ion implantation region in the unit monitor element shown in Fig. 8. (a) shows the case where the ion implantation region to be evaluated is positioned correctly, and (b) shows the case where the ion implantation region is positioned misaligned.

[0042] 9(a) shows a unit monitor element 900 in which a resistance region 1 having second conductivity type high concentration regions 2 (2A, 2B) at both ends is properly arranged with an ion implantation region 10 (10A) for forming a second conductivity type impurity diffusion region 8 arranged in a region inside the high concentration regions 2 (2A, 2B) and a connection portion 9 connecting the spaced apart impurity diffusion regions 8. The ion implantation region 10 (10A) has two regions into which ions are implanted to form a pair of second conductivity type impurity diffusion regions 8 arranged spaced apart from each other on the surface of the resistance region 1, and a connection region 11 connecting these two regions to each other.

[0043] In the normal arrangement, the connecting region 11 overlaps with the resistance region 1 by a predetermined amount in a second direction perpendicular to the first direction, so that a connection portion 9 is formed along one side parallel to the first direction of the resistance region 1. In the following description, the second direction will also be referred to as the direction from the resistance region toward the connecting region. Here, the specified magnitude is, for example, 3σ+T1·tanθ, where 3σ is the maximum allowable deviation, T1 is the vertical thickness of the photoresist placed on the top surface of resistance region 1, and θ is the angle of inclination from the perpendicular to the direction in which impurity ions are implanted. In this case, connection portion 9 will be formed in a normal manufacturing process.

[0044] Next, a case where the ion implantation region 10 (10A) is not normal and is arranged out of alignment will be described with reference to FIG. 9(b). In FIG. 9(b), the ion implantation region 10 (10A) is arranged away from the resistance region 1. In the drawing, the ion implantation region 10 (10A) is arranged out of alignment to the left, forming a gap 12. As a result, the impurity ions are not implanted along one side of the resistance region 1 in the first direction, and therefore a connection portion 9 is not formed between a pair of impurity diffusion regions 8. Therefore, the second conductivity type high concentration regions 2 (2A, 2B) at both ends are formed apart from each other, and therefore are not electrically connected.

[0045] As described above, the unit monitoring element 900 can detect that the ion-implanted region 10 (10A) has shifted in the direction from the resistive region toward the connecting region so as to narrow the connection portion 9 formed with the resistive region 1, resulting in a state in which there is a gap 12 with the resistive region 1, by detecting no current flowing through the resistive region 1 when a voltage is applied from the measurement terminals 4 (4A, 4B). In terms of Figures 8 and 9, the unit monitoring element 800 can detect the shift of the ion-implanted region 10 (10A) to the left on the paper of Figures 8 and 9.

[0046] Next, a semiconductor device having an alignment evaluation element that is composed of a plurality of unit monitor elements and can detect deviations in four directions of an ion implantation region will be described.

[0047] FIG. 10 is a diagram showing the positional relationship between a polysilicon resistance region and an ion implantation region in an alignment evaluation element using a plurality of unit monitor elements according to the second embodiment of the present invention. The alignment evaluation element 1000 is formed by independently arranging four unit monitor elements 900 shown in Fig. 9. The direction from the resistance region 1 toward the connection region 11 of the ion implantation regions 10 (10A, 10B, 10C, 10D) in each unit monitor element is different, and the unit monitor elements are arranged in four directions, up, down, left and right, parallel to the plane of the paper on which Fig. 10 is shown.

[0048] When arranged in this manner, a voltage is applied between the high concentration regions 2 at both ends of each unit monitoring element, and by determining whether or not a current flows, it becomes possible to detect the presence or absence of a deviation exceeding the maximum allowable value in any of the four directions of the ion implantation region 10. If there is a unit monitoring element through which no current flows between the high concentration regions 2, it is possible to detect the occurrence of a deviation in the direction from the resistance region 1 of that unit monitoring element toward the connecting region 11. Incidentally, by connecting a plurality of unit monitoring elements in series among the unit monitoring elements included in the alignment evaluation element 1000 shown in Fig. 10, it is possible to detect the presence or absence of a deviation exceeding the maximum allowable value in any of the directions detectable by the unit monitoring elements connected in series with a single current measurement. In other words, when no current flows, it is possible to detect the presence of a deviation exceeding the maximum allowable value in any of the directions.

[0049] As described above, according to the present invention, it is possible to provide a semiconductor device having an alignment evaluation element made of a basic minitor element capable of detecting with high accuracy the positional deviation of an impurity formation region defined by the position where an ion implantation region is formed, thereby making it possible to obtain a semiconductor device with little variation in quality. [Explanation of symbols]

[0050] 1 Polysilicon resistor area 2, 2A, 2B High concentration areas of polysilicon 3. Photoresist 4, 4A, 4B Measurement terminals 5, 5A, 5B Contacts 7 Ion implantation direction 8. Impurity diffusion region on polysilicon 9 Connection 10, 10A, 10B, 10C, 10D Ion implantation area 11 Consolidation area 12 Gap 20 Field oxide X Design setting value T1 Photoresist film thickness on polysilicon

Claims

1. 1. A semiconductor device comprising: an alignment evaluation element formed on a semiconductor substrate, the alignment evaluation element evaluating the quality of alignment between an impurity diffusion region formed by implanting impurity ions into the semiconductor substrate and a resistance element made of polysilicon, the semiconductor device comprising: the alignment evaluation element has a unit monitor element, The unit monitor element is a resistive region of a first conductivity type or a non-doped resistive region containing no impurities and made of polysilicon having a rectangular shape; a pair of high concentration regions of a second conductivity type made of polysilicon provided in contact with both ends of the resistor region in a first direction, a pair of impurity diffusion regions of a second conductivity type formed on a surface of the resistor region and spaced apart from each other in the first direction, the pair of impurity diffusion regions being in contact with the high concentration regions, respectively; a second conductive type ion implantation region including the set of impurity diffusion regions and provided outside the resistance region, the second conductive type ion implantation region being made up of a connection region connecting the set of impurity diffusion regions; having when a relative position between the ion implantation region and the resistance region in a second direction perpendicular to the first direction is shifted by a reference amount or more, a connection portion of a second conductivity type is formed in the resistance region, the connection portion connecting the pair of impurity diffusion regions to each other; The semiconductor device is capable of identifying the presence or absence of a deviation of the ion implantation region from the resistance region based on the electrical characteristic measurement result for the resistance region from the unit monitor element.

2. 1. A semiconductor device comprising: an alignment evaluation element formed on a semiconductor substrate, the alignment evaluation element evaluating the quality of alignment between an impurity diffusion region formed by implanting impurity ions into the semiconductor substrate and a resistance element made of polysilicon, the semiconductor device comprising: the alignment evaluation element has a unit monitor element, The unit monitor element is a resistive region of a first conductivity type or a non-doped resistive region containing no impurities and made of polysilicon having a rectangular shape; a pair of high concentration regions of a second conductivity type made of polysilicon provided in contact with both ends of the resistor region in a first direction, a pair of impurity diffusion regions of a second conductivity type formed on a surface of the resistor region and spaced apart from each other in the first direction, the pair of impurity diffusion regions being in contact with the high concentration regions, respectively; a second conductive type ion implantation region including the set of impurity diffusion regions, covering a part of a surface of the resistance region along one side of the resistance region, the second conductive type ion implantation region being a connection region connecting the set of impurity diffusion regions; having when a relative position between the ion implantation region and the resistance region in a second direction perpendicular to the first direction is shifted by a reference amount or more, a connection portion of a second conductivity type connecting the pair of impurity diffusion regions to each other is removed in the resistance region; The semiconductor device is capable of identifying the presence or absence of a deviation of the ion implantation region from the resistance region based on the electrical characteristic measurement result for the resistance region from the unit monitor element.

3. A semiconductor device as described in claim 1 or 2, wherein the alignment evaluation element includes a plurality of the unit monitor elements.

4. A semiconductor device described in any one of claims 1 to 3, wherein the unit monitor element has a measurement terminal above the high concentration region and connected to the high concentration region via a contact.

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