Method for electrically detecting positional deviation of contact hole in semiconductor device

Abstract: A method for detecting a positional deviation of a contact hole formed in an interlayer insulator layer includes the steps of forming a detection conductor pattern on a substrate at a peripheral portion of a contact hole formation area in which a contact hole is to be formed, and forming a first insulating layer to cover the detection conductor pattern. Then, a first conducting layer of a predetermined pattern is formed on the first insulating layer to cover the contact hole formation area, and a second insulating layer is formed to cover the first conducting layer. Furthermore, a contact hole is formed at the contact hole formation area in the second insulating layer, and a second conducting layer is deposited on the second insulation layer so that the second conducting layer is deposited within the contact hole. Thereafter, a short-circuit between the detection conductor pattern and one of the first and second conducting layers is detected. When the short-circuit is detected, it is judged that the formed contact hole adversely deviates from a proper position where the contact hole is to be formed.

Description: This invention relates to methods of manufacturing and testing multilayer semiconductor devices. An example of such a device is described in patent document EP-A-0295065 which discloses the preamble of claim 1 of this application. The device disclosed therein comprises: a semiconductor substrate; a conductor pattern formed on the substrate; a first insulating layer formed on the conductor pattern and portions of the substrate not covered by the conductor pattern; a patterned first conducting layer formed on the first insulating layer; a second insulating layer formed on the first conducting layer and on portions of the first insulating layer not covered by the first conducting layer, a contact hole being formed through at least the second insulating layer; and a second conducting layer formed on the second insulating layer and into the contact hole. It so happens that, in the example in EP-A-0295065, the first conducting layer covers (as viewed in a direction normal to the layers) an intended area for forming the contact hole; and the conductor pattern extends towards (as viewed in said direction) the intended hole formation area and is partially overlapped (as viewed in said direction) by the first conducting layer. The device may have other conducting and insulating layers. During manufacture of such a device, if the position of the contact hole were to deviate from the intended hole formation area, this could be detected by observing a vernier calipers pattern formed on the device using an optical microscope. However, visual human inspection with an optical microscope is very low in efficiency. The present invention is concerned with detection of deviation in the position of such a contact hole without requiring visual inspection using an optical microscope. The present invention provides a method as claimed in claim 1. This method enables deviation of the position of the contact hole from the intended hole formation area to be detected electrically and the method therefore lends itself to automation. Preferred features of the method are set forth in the other claims. Specific embodiments of the present invention will now be described, purely by way of example, with reference to the accompanying drawings, in which: Figure 1A is a diagrammatic plan view of a semiconductor device formed with one embodiment of a contact hole deviation checking conductor pattern in accordance with the present invention, in the case of no adverse deviation of the contact hole; Figure 1B is a diagrammatic sectional view taken along the line I-I in Figure 1A; Figure 2A is a diagrammatic plan view of a semiconductor device formed with one embodiment of a contact hole deviation checking conductor pattern in accordance with the present invention, in the case of an adverse deviation of the contact hole; Figure 2B is a diagrammatic sectional view taken along the line II-II in Figure 2A; and Figure 3 is a diagrammatic plan view of a semiconductor device formed with another embodiment of a contact hole deviation checking conductor pattern in accordance with the present invention, in the case of no adverse deviation of the contact hole. Referring to Figures 1A and 1B, there are shown a diagrammatic plan view of a semiconductor device formed with one embodiment of a contact hole deviation checking conductor pattern in accordance with the present invention, in the case of no adverse deviation of the contact hole, and a diagrammatic sectional view taken along the line I-I in Figure 1A. The shown device includes a silicon substrate 10 and an insulating cover layer 12 formed to cover an upper surface of the silicon substrate 10. On the insulating cover layer 12, there is formed a contact hole deviation checking conductor pattern composed of four strip-shaped detection conductors 14A, 14B, 14C and 14D, each of which is formed to extend outwardly radially from a position slightly separated from a corresponding side of a rectangular contact hole formation area 16 in a plan view, as seen from Figure 1A. The strip-shaped detection conductors 14A, 14B, 14C and 14D are located at equal angular intervals with regard to a center of the contact hole formation area 16, and extend in four directions orthogonal to one another in the shown embodiment. In addition, an edge of each of the detection conductors 14A, 14B, 14C and 14D near to the contact hole formation area 16 is separate from an outer edge of the contact hole formation area 16 by some distance which corresponds to, for example, a maximum admissible amount of a positional deviation of a contact hole. Furthermore, a first insulating layer 18 is deposited to cover the detection conductors 14A, 14B, 14C and 14D and a portion of the insulating cover layer 12 on which the detection conductors 14A, 14B, 14C and 14D are not formed. On the first insulating layer 18, a first or lower conducting layer 20 is formed and patterned in alignment with but larger in size than the contact hole formation area 16 in a plan view, as seen from Figure 1A. in addition, a peripheral portion of the lower conducting layer 20 partially overlaps with each of the detection conductors 14A, 14B, 14C and 14D in a plan view, as also seen from Figures 1A and 1B. A second insulating layer 22 is deposited to cover the lower conducting layer 20 and a portion of the first insulating layer 18 on which the lower conducting layer 20 is not formed. This second insulating layer 22 serves as an interlayer insulator. Then, a contact hole 24 is formed in conformity with or in matching with the contact hole formation area 16 to pierce through the interlayer insulating layer 22. In ordinary cases, the size of the contact hole 24 is sufficiently smaller than that of the lower conducting layer 20. Therefore, if the formed contact hole 24 does not deviate from the contact hole formation area 16, namely, is in alignment with the contact hole formation area 16, an etching for formation of the contact hole 24 is blocked by the lower conducting layer 20. In other words, the contact hole 24 is positioned on only the lower conducting layer 20. A second or upper conducting layer 26 is formed to fulfil in the contact hole 24 and patterned to form a desired wiring conductor. Thus, as seen from Figures 1A and 1B, if the contact hole 24 is formed with no positional deviation, namely, if the formed contact hole 24 coincides with the contact hole formation area 16, only the lower and upper conducting layers 20 and 26 are interconnected by action of the contact hole 24. However, if the formation position of the contact hole 24 substantially deviates as shown in Figures 2A and 2B, namely if the contact hole 24 is formed to partially protrude out of the lower conducting layer 20, the etching for formation of the contact hole is not completely blocked by the lower conducting layer 20, and the first insulating layer 18 between the detection conductor 14A and the lower conducting layer 20 is partially removed so that the contact hole 24 partially reaches to the detection conductor 14A. As a result, the upper conducting layer 26 having filled in the contact hole 24 has a portion 28 short-circuiting between the upper conducting layer 26 and the detection conductor 14A. Therefore, by applying a voltage between the upper conducting layer 26 and the detection conductor 14A (for example, by applying a voltage between an electrode pad (not shown) connected to the upper conducting layer 26 and exposed at an outside of the semiconductor device and another electrode pad (not shown) connected to the detection conductor 14A and also exposed at an outside of the semiconductor device), the short-circuit between the upper conducting layer 26 and the detection conductor 14A can be known in an electric measurement manner. If a short-circuit can be detected between the upper conducting layer 26 and any one of the detection conductors 14A, 14B, 14C and 14D, it can be concluded that the formed contact hole 24 deviates from a proper formation position. To the contrary, if no short-circuit can be detected between the upper conducting layer 26 and any one of the detection conductors 14A, 14B, 14C and 14D, it can be concluded that the contact hole 24 is formed at a proper formation position with no positional deviation or with an admissible positional deviation. In addition, if a contact hole larger than a desired size is formed at a proper formation position or with an admissible positional deviation, a short-circuit also occurs between the upper conducting layer 26 and the detection conductors 14A, 14B, 14C and 14D. Therefore, whether or not the formed contact hole has a desired size, namely, a size of the formed contact hole can be known by detecting a short-circuit between the upper conducting layer 26 and all the detection conductors 14A, 14B, 14C and 14D. In the above mentioned embodiment, the short-circuit has been detected between the upper conducting layer 26 and the detection conductors 14A, 14B, 14C and 14D. However, the short-circuit can been detected between the lower conducting layer 20 and the detection conductors 14A, 14B, 14C and 14D, as seen from Figure 2B. Furthermore, in the above mentioned example shown in Figures 2A and 2B, the upper conducting layer 26 and the detection conductor 14A are short-circuited. Since there are provided the four detection conductors 14A, 14B, 14C and 14D separate from one another and orthogonal to one another, a direction of the positional deviation of the contact hole can be determined by inspecting which of the four detection conductors 14A, 14B, 14C and 14D short-circuits with the upper conducting layer 26. In the above mentioned example shown in Figure 2A, it can be judged on the basis of the short-circuit between the upper conducting layer 26 and the detection conductor 14A that the contact hole 24 has deviated in a right-hand direction of the proper formation position. However, if it is not necessary to know the direction of the positional deviation of the formcd contact hole, the four detection conductors 14A, 14B, 14C and 14D can he replaced with a single detection conductor which extends to surround the contact hole formation area. Referring to Figure 3, there is shown a diagrammatic plan view of a semiconductor device formed with another embodiment of a contact hole deviation checking conductor pattern in accordance with the present invention, in the case of no adverse deviation of the contact hole. In the second embodiment, each detection conductor 14A, 14B, 14C or 14D formed in proximity with each side of the rectangular contact hole formation area 16 is divided into three separate sub-conductors 30A, 30B and 30C (32A, 32B and 32C, 34A, 34B and 34C, and 36A, 36B and 36C) which extend in parallel to the side concerned of the rectangular contact hole formation area 16, separately from the side concerned of the rectangular contact hole formation area 16 by different distances in a direction perpendicular to the side concerned of the rectangular contact hole formation area 16. The lower conducting layer 20 is formed to partially overlap with an innermost one of the three separate sub-conductors 30A, 32A, 34A, and 36A, and the upper conducting layer is formed to have a size sufficient to overlap at least partially with an outermost one of the three separate sub-conductors 30C, 32C, 34C, and 36C. In the second embodiment, not only the direction but also the amount of the positional deviation of the contact hole can be known by detecting which of the four detection conductors short-circuits with the upper or lower conducting layer 20 or 26 and by detecting which of the three sub-conductors (for example, 30A, 30B and 30C) short-circuits with the upper or lower conducting layer 20 or 26. In the above mentioned embodiments, the detection conductors or subconductors can be formed of wiring conductors necessary to the operation of the semiconductor device. As seen from the above explanation of the preferred embodiments the detection conductor is formed at a position slightly separate from a contact hole formation area and at a level lower or deeper than a level at which a bottom of a contact hole is to be positioned. An electrical short-circuit between the detection conductor and the upper or lower conducting layer is detected for knowing a positional deviation of the formed contact hole. In other words, since the positional deviation of the formed contact hole can be detected in an electric manner, it is possible to greatly elevate the efficiency for checking the positional deviation of the formed contact hole. The invention has thus been shown and described with reference to the specific embodiments. However, it should be noted that the present invention is in no way limited to the details of the illustrated structures but changes and modifications may be made within the scope of the appended claims.

Claims: A method of manufacturing a multi-layer semiconductor device, comprising the steps of:- forming a conductor pattern (14A,14B,14C,14D) on a semiconductor substrate (10,12); forming a first insulating layer (18) on the substrate and the conductor pattern; forming a patterned first conducting layer (20) on the first insulating layer; forming a second insulating layer (22) on the first insulating layer and first conducting layer; forming a contact hole (24) through at least the second insulating layer; and forming a second conducting layer (26) on the second insulating layer and into the contact hole; wherein: the first conducting layer covers, as viewed in a direction normal to the layers, an intended area for forming the contact hole is formed in such a manner that it is substantially in alignment with, as viewed in said direction, but larger in size than the intended hole formation area; and the conductor pattern extends, as viewed in said direction, towards the intended hole formation area and is partially overlapped, as viewed in said direction, by the first conducting layer, the conductor pattern including a plurality of conductors (14A,14B,14C,14D) each extending outwardly, as viewed in said direction, away from the intended hole formation area at equal angular intervals, the conductors being separate from one another; characterised in that: the conductor pattern is a detection conductor pattern for use in detecting a possible deviation of the position of the contact hole from the intended hole formation area, a peripheral portion of the first conducting layer is at least partially overlapping with each detection conductor, and said second conducting layer is formed such that it has a size sufficient to at least partially overlap with each detection conductor, as viewed in said direction; and the manufacturing method is combined with a testing method of testing for a short-circuit between the detection conductor pattern and the first or second conducting layer due to the contact hole being formed at a position deviating from the intended hole formation area, the formation of the contact hole therefore not having been arrested by the first conducting layer, and the contact hole therefore having extended as far as the detection conductor pattern, so that such a short-circuit is formed, the testing method comprising the steps of testing for a short-circuit between each of the detection conductors and the first or second conducting layer, and the method further includes the step of determining a direction of deviation of the formed contact hole from the intended hole formation area on the basis of which of the conductors has or have a short-circuit with the first or second conducting layers. A method as claimed in any preceding claim, wherein the detection conductors include four conductors located at equal 90 degree intervals. A method as claimed in Claim 1 or 2, wherein the detection conductors extend radially outwardly away from, as viewed in said direction, the intended hole formation area. A method as claimed in Claim 1 or 2, wherein each of the detection conductors is divided into a plurality of sub-conductors (30A-C;32A-C;34A-C;36A-C) located at different distances, as viewed in said direction, from the intended hole formation area and being separate from one another, the short-circuit testing step comprising the steps of testing for a short-circuit between each of said plurality of sub-conductors of each of the detection conductors and the first or second conducting layer, and the method further includes the step of determining an amount and a direction of deviation of the formed contact hole from the intended hole formation area on the basis of which of the sub-conductors has or have a short-circuit with the first or second conducting layers.

Inventors: TAKAHASHI YASUSHI, TAKAHASHI, YASUSHI, TAKAHASHI, YASUSHI, C/O NEC CORPORATION
Applicants: NIPPON ELECTRIC CO, NEC CORPORATION
Application year: 1990
Main classification: H01L21
IPC codes: H01L21, G01R31, H01L23