JP2007081036A - Method of inspecting semiconductor device and method of manufacturing semiconductor device for inspection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of inspecting a semiconductor device which can detect a short of a contact plug effectively. <P>SOLUTION: This method of inspecting the semiconductor device comprises the steps of forming a pattern of an element isolation region 14 defining an element formation region 13 mutually, and an insulating film 16 coating a semiconductor substrate 11 on a surface part of the semiconductor substrate 11; using a mask pattern for forming a plurality of contact plugs conducted to the element formation region 13 of the semiconductor substrate, and shifting this mask pattern by a relative predetermined distance with respect to the pattern of the element isolation region 14, thereby forming the plurality of contact plugs 18 which pass through the insulating film 16 and are partially insulated by the element isolation region 14; irradiating electron beams to the contact plugs 18 insulated by the element isolation region 14 in the plurality of contact plugs 18; detecting an amount of secondary electrons released from the contact plugs 18 to which electron beams are irradiated; and determining an abnormality of the contact plugs 18 to which electron beams are irradiated, based on the detected amount of secondary electrons. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for inspecting a semiconductor device and a method for manufacturing a semiconductor device for inspection, and more particularly, a method for inspecting a short circuit between conductors arranged inside a semiconductor device. And a method of manufacturing a semiconductor device for inspection.

  A short circuit between conductors inside a semiconductor device causes a malfunction of the semiconductor device and is a major factor that reduces the yield of semiconductor device manufacturing. In recent years, the period from design to mass production of semiconductor device products has been increasingly shortened, and in-line inspections etc. prior to mass production can efficiently detect shorts between conductors inside semiconductor devices and adjust to process conditions with few shorts early. It is requested.

  Conventionally, in order to detect a short circuit between conductors, an inspection is performed with the naked eye using an optical inspection device. However, along with the miniaturization of semiconductor devices, inspection by an optical inspection apparatus requires a lot of time to find a location where a short circuit has occurred, and the detection itself has become difficult. In recent years, inspection using an SEM (Scanning Electron Microscope) type inspection apparatus has been put into practical use for this problem.

  An inspection method using the SEM type inspection apparatus is described in Patent Document 1, for example. FIG. 7A shows the configuration of an inspection semiconductor device used in the inspection method described in Patent Document 1. FIG.7 (b) has shown the cross section along the BB line of Fig.7 (a). In this inspection method, first, the conductor pattern 63 connected to the substrate 61 via the conductor 64 and the conductor pattern (non-connection pattern) 65 not connected to the substrate 61 are orthogonally crossed on the surface of the insulating film 62 of the semiconductor device. It is formed so as to be alternately arranged in any of the two directions. Next, the surface of the semiconductor device 60 is irradiated with an electron beam, and the amount of secondary electrons emitted from the conductor patterns 63 and 65 is measured while scanning the surface of the semiconductor device 60.

Here, if the non-connection pattern 65 irradiated with the electron beam is electrically connected to another conductor such as the normal conductor pattern 63, the amount of charge is reduced, and if the conductive pattern 65 is not conductive. Increases the amount of charge. Since the amount of secondary electrons emitted from the non-connected pattern 65 varies depending on the potential corresponding to the charge amount of the non-connected pattern 65, the non-connected pattern 65 in which an abnormality is observed in the amount of secondary electrons emitted is in the vicinity. It can be determined that a short circuit has occurred with the conductor. Further, by performing a precise inspection only in the vicinity of the non-connection pattern 65 that is determined to be short-circuited, it is possible to specify a detailed part where the short-circuit has occurred.
JP 2001-305194 A (FIGS. 1 and 2)

  By the way, with the recent miniaturization of semiconductor devices, the interval between adjacent word lines is becoming increasingly narrow. For this reason, defective filling of the insulating film is likely to occur between the word lines, and as a result, a short between the contact plug and the word line or a short via the contact plug such as a short between the contact plugs occurs. This is one of the main factors that deteriorate the quality of semiconductor devices. However, in the above conventional SEM inspection method, even if a contact plug short circuit is detected, each contact plug is electrically connected to another conductor such as a surface portion of a semiconductor substrate. Keep the same potential. Therefore, it is not easy to detect the short circuit.

  In order to greatly improve the yield of semiconductor device manufacturing, it is essential to detect contact plug shorts efficiently. In view of the above, an object of the present invention is to provide a method for inspecting a semiconductor device capable of efficiently detecting a short of a contact plug, and a method for manufacturing a semiconductor device for inspection.

In order to achieve the above object, a semiconductor device inspection method according to a first aspect of the present invention includes a base pattern including a conductive portion and an insulating portion on a substrate, and an insulating film covering the base pattern. Forming a step;
A mask pattern for forming a plurality of contact plugs conducting to the conductive portion is used, and the mask pattern is shifted by a predetermined distance relative to the base pattern, so that at least a part of the mask penetrates the insulating film. Forming a plurality of contact plugs insulated by the insulating portion;
Irradiating an electron beam to a contact plug insulated by at least the insulating portion among the plurality of contact plugs;
Detecting the amount of secondary electrons emitted from the contact plug irradiated with the electron beam;
And determining an abnormality of the contact plug irradiated with the electron beam based on the detected amount of secondary electrons.

A method of manufacturing an inspection semiconductor device according to the present invention is a method of manufacturing an inspection semiconductor device for inspecting a state of a product semiconductor device,
Forming a base pattern including a conductive portion and an insulating portion, and an insulating film covering the base pattern using the same process conditions as those for manufacturing the product semiconductor device; and
A mask pattern for forming a plurality of contact plugs that penetrate the insulating film and conduct to the conductive portion in the semiconductor device for product is used, and the mask pattern is shifted by a predetermined distance relative to the base pattern. And a step of forming a plurality of contact plugs penetrating the insulating film and insulated at least partially by the insulating portion.

A semiconductor device inspection method according to a second aspect of the present invention is a semiconductor device inspection method for evaluating a product semiconductor device using the inspection semiconductor device,
Irradiating an electron beam to a contact plug formed on at least the insulating portion of the plurality of contact plugs;
Detecting the amount of secondary electrons emitted from the contact plug irradiated with the electron beam;
And determining an abnormality of the contact plug irradiated with the electron beam based on the detected amount of secondary electrons.

  According to the method for inspecting a semiconductor device according to the present invention, a change in potential generated when a contact plug insulated by an insulating portion is short-circuited is detected by detecting an abnormal amount of secondary electrons emitted from the contact plug. The contact plug short circuit can be directly detected. As a result, it is possible to efficiently detect a short of the contact plug and greatly improve the yield of manufacturing the semiconductor device.

  Further, when forming a contact plug insulated by an insulating portion, a mask pattern for forming a plurality of contact plugs conducting to the conductive portion is used, so that the contact plug in the semiconductor device for inspection and its vicinity are It can be formed with the same structure as a conventional semiconductor device. Therefore, it is possible to accurately detect a short of the contact plug in the product semiconductor device.

  According to the method for inspecting a semiconductor device and the method for manufacturing a semiconductor device for inspection according to the first aspect of the present invention, during the manufacturing process of the semiconductor device for inspection, the conductivity is increased. Since it is only necessary to change the mask pattern for forming a plurality of contact plugs conductive to the portion by a predetermined distance relative to the base pattern, the cost required for manufacturing a semiconductor device for inspection can be reduced.

  In the semiconductor device inspection method and the inspection semiconductor device manufacturing method according to the first aspect of the present invention, the conductive portion and the insulating portion of the base pattern are an element formation region and an element isolation region of the semiconductor substrate, respectively. Alternatively, the conductive portion of the base pattern may be a wiring pattern formed by selective etching of a conductor film. In the inspection semiconductor device manufacturing method according to the present invention, the product semiconductor device may be a DRAM.

  In the abnormality determination step of the semiconductor device inspection method according to the second aspect of the present invention, for example, a contact plug insulated by the insulating portion is replaced with the conductive portion, another contact plug, and another conductive material. It can be determined whether or not the conductive material is conductive.

  Hereinafter, embodiments of the present invention will be described specifically and in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing a configuration of an inspection semiconductor device for inspecting a state of a product semiconductor device. The semiconductor device 10 is configured as a DRAM (Dynamic Random Access Memory) and includes a semiconductor substrate 11. An element isolation groove 12 in which an insulating material is embedded in a predetermined pattern is formed on the surface portion of the semiconductor substrate 11, and an element isolation region 14 constituted by the element isolation groove 12 is an element formation region 13 in which a semiconductor element is formed. Are partitioned from each other.

  A plurality of word lines 15 are formed on the semiconductor substrate 11 via a gate insulating film (not shown), and an insulating film 16 is formed so as to cover the word lines 15. A contact hole 17 that penetrates the insulating film 16 and is connected to the semiconductor substrate 11 is opened, and a contact plug 18 made of a conductive material is formed by filling the inside of the contact hole 17. The contact hole 17 is formed to be connected to the surface of the semiconductor substrate 11 between adjacent word lines 15 by a SAC (Self Align Contact) method using an insulating film covering the surface of the word line 15 as a mask.

  In one element formation region 13, three word lines 15 intersect, and two contact plugs 21 that contact the semiconductor substrate 11 adjacent to the word lines 15 are formed. In one element isolation region 14, one contact plug (non-contact contact plug) 22 is formed adjacent to the word line 15 and insulated by the element isolation groove 12. The element formation region 13, the word line 15, and the contact plug 18 are arranged at equal intervals.

  FIG. 2 shows a planar structure of the semiconductor device 10 for inspection shown in FIG. FIG. 1 shows a cross section viewed along line II in FIG. The element formation region 13 has a rectangular shape, and the word line 15 intersects with the longitudinal direction of the element formation region 13 in an oblique direction.

  FIG. 3 is a cross-sectional view showing a configuration of a product semiconductor device corresponding to the inspection semiconductor device of FIG. In the semiconductor device 30, two contact lines 18 are formed in one element formation region 13 so that two word lines 15 intersect and contact the semiconductor substrate 11 adjacent to the word lines 15. One word line 15 intersects one element isolation region 14. The central contact plug 18 is connected to an upper bit line (not shown) to form a bit line connection contact plug 23, and the contact plugs 18 at both ends are connected to an upper storage node (not shown) to connect a storage node connection contact. Plugs 24 and 25 are configured.

4 shows the planar structure of the semiconductor device of FIG. 3, wherein the horizontal direction is the X direction and the vertical direction is the Y direction. FIG. 3 shows a cross section taken along line III-III in FIG. The semiconductor device 30 includes a unit cell 33 at one intersection 6F2, and the dimension of the unit cell 33 is 2F in the X direction 31 and 3F in the Y direction 32, where F is a half length of the pitch of the word lines 15. And its area is 6F ² (2F × 3F). The semiconductor device 30 has a unit cell 33 and a twin cell structure in which the structure on the semiconductor substrate 11 is repeatedly arranged in pairs with a unit cell 34 having a shape symmetrical with the shape of the unit cell 33.

  1 and 2, in the semiconductor device 10 for inspection, the pattern of the element isolation region 14 is F in the X direction 31 and 32 in the Y direction with respect to the product semiconductor device 30 as indicated by reference numeral 35. It is formed so as to be shifted overall by 0.5F. As a result, one storage node connection contact plug 24 in the product semiconductor device 30 is connected to the element isolation region 14 to form a non-contact contact plug 22. The bit line connection contact plug 23 and the other storage node connection contact plug 25 in the product semiconductor device 30 are connected to the element formation region 13 in the same manner as the contact plug in the product semiconductor device 30. The contact plug 21 is configured. In the semiconductor device 10 for inspection, the structure above the insulating film 16 in the semiconductor device 30 for products is not formed.

  In the semiconductor device inspection method according to the present embodiment, each contact plug 18 is scanned while irradiating the surface of the semiconductor device 10 for inspection with an SEM type inspection device and scanning the surface of the semiconductor device 10. Measure the amount of secondary electrons emitted from. As shown in FIG. 5, the SEM type inspection device measures the amount of secondary electrons, and as shown in FIG. 5, the potential contrast for displaying the position of each contact plug 18 with the brightness corresponding to the amount of secondary electrons emitted from each contact plug 18. An image 50 is displayed. In the figure, reference numerals 51 to 53 denote non-contact contact plugs 22, normal contact plugs 21 constituting the bit line connection contact plugs 23, and normal contact plugs 21 constituting the storage node connection contact plugs 25. Each corresponding part is shown.

  When the unconnected contact plug 22 is not short-circuited with other conductors, the unconnected contact plug 22 is charged positively or negatively. On the contrary, when the non-contact contact plug 22 is short-circuited with the word line 15, for example, electrons are released through the word line 15, so that the charge amount of the non-contact contact plug 22 is small. Similarly, when the unconnected contact plug 22 is short-circuited with the normal contact plug 21, the charge amount of the unconnected contact plug 22 is small.

  Since the amount of secondary electrons emitted from the contact plug 18 varies depending on the potential corresponding to the charge amount of each contact plug 18, the short-circuited non-contact contact plug 22 is not short-circuited in the potential contrast image 50. Displayed with a brightness different from that of the plug 22. Accordingly, the luminance of each non-connected contact plug 22 is observed in the potential contrast image 50, and the non-connected contact plug 22 displayed with a luminance different from that of the other non-connected contact plugs 22 is short-circuited with the non-connected contact plugs 22. Can be judged.

  When detecting the short-circuited non-contact contact plug 22, an upper limit or lower limit threshold value of the amount of secondary electrons emitted from the non-connection contact plug 22 is set, and non-connection that exceeds or falls below these threshold values. The contact plug 22 may be determined as a short-circuited unconnected contact plug 22.

  By conducting a more precise inspection on the non-connected contact plug 22 determined to be short-circuited, it is possible to identify a detailed short-circuited portion. Note that the positive and negative charges and the amount of charge of the non-contact plug 22 vary depending on the material and size of the non-contact plug 22, the material of the insulating film 16, and the energy level of the irradiated electron beam.

  6A to 6C are cross-sectional views sequentially showing manufacturing steps for manufacturing the semiconductor device for inspection shown in FIGS. First, as shown in FIG. 6A, an element isolation groove 12 is formed in a predetermined pattern shape on a surface portion of a semiconductor substrate 11 by a known method, and an element isolation region 14 constituted by the element isolation groove 12 is used. The element formation region 13 is partitioned.

  After forming a gate insulating film (not shown) on the semiconductor substrate 11, a conductive film 41 and an insulating film 42 are sequentially formed on the gate insulating film. The insulating film 42 and the conductive film 41 are patterned using a known photolithography technique and etching technique to form the word line structure 43. When the word line structure 43 is formed, patterning is performed so that the three word line structures 43 intersect the element formation region 13 and do not intersect the element isolation region 14. An insulating film is formed on the entire surface covering the word line structure 43, and then etched back to form sidewalls 44 on the side surfaces of the word line structure 43 (FIG. 6B).

  After the insulating film 45 is formed on the entire surface, the insulating film 45 is opened in a self-aligning manner using the side wall 44 as a mask by using a known photolithography technique and etching technique, and the contact hole 17 exposing the semiconductor substrate 11 is formed. Form. When the contact hole 17 is formed, a contact hole 46 exposing the element formation region 13 of the semiconductor substrate and a contact hole 47 exposing the element isolation region 14 are formed (FIG. 6C).

  Subsequently, the contact plug 18 is formed by embedding the inside of the contact hole 17 with a conductive material using a known method. The contact plugs 18 accommodated in the contact holes 46 and 47 constitute the normal contact plug 21 and the non-contact contact plug 22, respectively, and the semiconductor device 10 for inspection shown in FIG. 1 can be manufactured.

  The method of manufacturing the semiconductor device 10 for inspection is that the pattern of the element isolation region 14 is shifted by a distance indicated by reference numeral 35 and the structure above the insulating film 16 is not formed. This is the same as the manufacturing method of the product semiconductor device 30 shown in FIGS.

  According to the method for inspecting a semiconductor device according to the present embodiment, the storage node connection contact plug 24 in the product semiconductor device 30 is insulated by the element isolation region 14 of the semiconductor substrate to form the non-connection contact plug 22. The semiconductor device 10 is manufactured. In this semiconductor device 10 for inspection, a change in potential that occurs when the non-connected contact plug 22 is short-circuited is detected based on an abnormality in the amount of secondary electrons emitted from the non-connected contact plug 22. A short of the contact plug 24 can be directly detected. As a result, it is possible to efficiently detect a short of the contact plug and greatly improve the yield of manufacturing the semiconductor device.

  By the way, in the semiconductor device shown in FIGS. 7A and 7B, the contact plug 65 is connected to the element isolation groove formed in the surface portion of the semiconductor substrate 61 via the contact plug. It is also possible to detect a short circuit. However, in this case, since the structure of the contact plug, the word line, and the like is not the same as that of the product semiconductor device, it is not easy to accurately evaluate a short between the contact plug and the word line or between the contact plugs. In addition, since the mask for forming the contact plug is not the same as that used in the product semiconductor device, an additional cost for manufacturing the mask is required.

  However, in the semiconductor device for inspection 10 according to the present embodiment, the pattern of the element isolation region 14 is formed so as to be shifted as a whole, and the structure above the insulating film 16 is not formed. The same configuration as the semiconductor device 30 for products is provided. That is, in the semiconductor device 10 for inspection, the word line 15, the contact plug 18, and the insulating film 16 that accommodates them have the same configuration as the product semiconductor device 30. A short of the contact plug 18 can be accurately detected.

  Further, when manufacturing the semiconductor device 10 for inspection, it is only necessary to change the mask used for forming the pattern of the element isolation region 14 by a predetermined distance during the manufacturing process of the semiconductor device 30 for products. The cost required for manufacturing the semiconductor device 10 for inspection can be reduced. Instead of the mask used when forming the pattern of the element isolation region 14, the mask for forming the pattern of the word line 15 and the contact hole 17 formed on the semiconductor substrate 11 is shifted by a predetermined distance. The semiconductor device 10 for inspection can also be manufactured by making a change.

  In the method for inspecting a semiconductor device according to the present embodiment, when detecting the shorted non-connected contact plug 22, the non-connected contact plug 22 having a luminance different from that of the other non-connected contact plugs 22 with reference to the potential contrast image 50. By using this method, it is possible to easily detect the short-circuited unconnected contact plug 22.

  In the above embodiment, each of the normal contact plugs 21 is electrically connected to the element forming region 13, and thus is maintained at substantially the same potential after irradiation with the electron beam, so that it is not easy to detect a short circuit between them. However, for example, the bit line connection contact plug 23 or the other storage node connection contact plug 25 is aligned with the element isolation region 14 separately from the inspection semiconductor device 10, and the non-connection contact plug 22. By manufacturing the semiconductor device for inspection, it is possible to detect a short circuit of the contact plugs 23 and 25.

  In addition, it is possible to detect not only a contact plug that penetrates the insulating film 16 formed on the surface of the semiconductor substrate 11 but also a short of a contact plug that penetrates an upper insulating film formed on the insulating film 16. In this case, for example, a part of the contact plug that penetrates the upper insulating film is connected to a conductor such as a wiring pattern formed by selective etching of the conductor film or a lower contact plug to form a normal contact plug, Another contact plug is connected to the surface of the lower insulating film or the like to form a non-contact contact plug. Also in this case, in the method for manufacturing a semiconductor device for products, by shifting one or more predetermined masks by a predetermined amount, the same mask as that used for manufacturing the semiconductor device for products is used for inspection. A semiconductor device can be manufactured.

  Although the present invention has been described based on the preferred embodiment, the semiconductor device inspection method and the inspection semiconductor device manufacturing method according to the present invention are not limited to the configuration of the above embodiment. In addition, a method for inspecting a semiconductor device and a method for manufacturing a semiconductor device for inspection that have been variously modified and changed from the configuration of the above embodiment are also included in the scope of the present invention.

It is sectional drawing which shows the structure of the semiconductor device for a test | inspection which concerns on one Embodiment of this invention. FIG. 2 is a plan view showing a planar structure of the semiconductor device of FIG. 1. It is sectional drawing which shows the structure of the semiconductor device for products. FIG. 4 is a plan view showing a planar structure of the semiconductor device of FIG. 3. It is a top view which shows typically the electric potential contrast image obtained by the measurement of the semiconductor device of FIG. 6A to 6C are cross-sectional views sequentially showing manufacturing steps for manufacturing the semiconductor device of FIGS. FIG. 7A is a plan view showing the configuration of the semiconductor device for inspection described in Patent Document 1, and FIG. 7B shows a cross section taken along line BB in FIG. 7A. It is sectional drawing.

Explanation of symbols

10: Semiconductor device for inspection 11: Semiconductor substrate 12: Element isolation trench 13: Element formation region 14: Element isolation region 15: Word line 16: Insulating film 17: Contact hole 18: Contact plug 21: (Normal) contact plug 22: Unconnected contact plug 23: Bit line connection contact plug 24, 25: Storage node connection contact plug 31: X direction 32: Y direction 33, 34: Unit cell 35: Pattern shift amount 41 in the element isolation region 41: Conductive film 42: Insulating film 43: Word line structure 44: Side wall 45: Insulating film 46, 47: Contact hole 50: Potential contrast image 51: Portion 52 corresponding to non-connected contact plug, 53: Corresponding to normal contact plug To do

Claims (9)

Forming a base pattern including a conductive portion and an insulating portion on the substrate, and an insulating film covering the base pattern;
A mask pattern for forming a plurality of contact plugs conducting to the conductive portion is used, and the mask pattern is shifted by a predetermined distance relative to the base pattern, so that at least a part of the mask penetrates the insulating film. Forming a plurality of contact plugs insulated by the insulating portion;
Irradiating an electron beam to a contact plug insulated by at least the insulating portion among the plurality of contact plugs;
Detecting the amount of secondary electrons emitted from the contact plug irradiated with the electron beam;
And a step of determining an abnormality of the contact plug irradiated with the electron beam based on the detected amount of secondary electrons.   The semiconductor device inspection method according to claim 1, wherein the conductive portion and the insulating portion of the base pattern are an element formation region and an element isolation region of a semiconductor substrate, respectively.   The method for inspecting a semiconductor device according to claim 1, wherein the conductive portion of the base pattern is a wiring pattern formed by selective etching of a conductor film. A method of manufacturing an inspection semiconductor device for inspecting a state of a product semiconductor device,
Forming a base pattern including a conductive portion and an insulating portion, and an insulating film covering the base pattern using the same process conditions as those for manufacturing the product semiconductor device; and
A mask pattern for forming a plurality of contact plugs that penetrate the insulating film and conduct to the conductive portion in the semiconductor device for product is used, and the mask pattern is shifted by a predetermined distance relative to the base pattern. And a step of forming a plurality of contact plugs that penetrate the insulating film and at least a part of which is insulated by the insulating portion.   The method for manufacturing a semiconductor device for inspection according to claim 4, wherein the conductive portion and the insulating portion of the base pattern are an element formation region and an element isolation region of a semiconductor substrate, respectively.   The manufacturing method of the semiconductor device for a test | inspection of Claim 4 whose electroconductive part of the said base pattern is a wiring pattern formed by the selective etching of a conductor film.   The manufacturing method of the semiconductor device for a test | inspection as described in any one of Claims 4-6 whose said semiconductor device for products is DRAM. A semiconductor device inspection method for evaluating a product semiconductor device using the inspection semiconductor device according to any one of claims 4 to 7,
Irradiating an electron beam to a contact plug formed on at least the insulating portion of the plurality of contact plugs;
Detecting the amount of secondary electrons emitted from the contact plug irradiated with the electron beam;
And a step of determining an abnormality of the contact plug irradiated with the electron beam based on the detected amount of secondary electrons.   In the abnormality determination step, it is determined whether or not the contact plug insulated by the insulating portion is electrically connected to at least one of the conductive portion, another contact plug, and another conductive material. Item 9. A method for inspecting a semiconductor device according to Item 8.

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