Method of forming a wiring pattern of a semiconductor integrated circuit device

Abstract: A wiring pattern of a semicon­ ductor integrated circuit device of the present inven­ tion comprises a wiring portion (P) extending from a connection hole (22) and a connection portion (Q) located on the connection hole and having a matching allowance (B) with respect to said connection hole on said wiring portion side being formed wider than a predetermined matching allowance by a predetermined width with which a required yield of successful matching can be assured.

Description: The present invention relates to a method of forming a wiring pattern in a semiconductor integrated circuit device. From EP 0 166 344 an emitter contact structure is known, comprising a contact opening and a contact stripe in and around the contact opening. A margin between the opening and the wiring portion of the stripe is shown to be larger than the remaining margins of the stripe around the opening. Conventionally, matching allowance between a connecting hole (e.g., a contact hole or a through hole) and a wiring is set equally around the connecting holes, in order to compensate for the deviation which occurs in the step of lithography randomly in every direction. When the deviation is zero, around width H at the periphery of the connecting hole is formed with an equal width as shown in Figs. 1A and 1B, which illustrate a connecting hole 11, wiring layer 12, and an inter-layer insulation layer 13. As is shown in Fig. 13, a notch S is formed in the wiring layer on the connection hole 11. When electric current flows through the connection hole 11, resistance against the current increases at the section where the notch S locates. The wiring resistance around connection hole 11 (to be called "connection hole resistance" hereinafter) can be substituted with an equivalent circuit shown in Fig. 2, which is designed so that when deviation between the connection hole 11 and the pattern of the wiring 12 is zero, current paths I 2 and I 2 ' on the wiring extension side become wide enough. In reality, however, due to a matching error α in the step of pattern matching, a variety of deviations may occur between the connection hole 11 and the wiring layer 12. Figs. 3A to 3C illustrate several examples of matching deviation between the connection hole 11 and the wiring layer 12. Fig. 3A shows a case where the connection hole 11 deviates in the direction opposite to the wiring extension side. In this case, as the around width B 1 narrows, resistances R 3 and R 3 ' inevitably increase. However, electrical current I 3 , which is affected by the resistances, comprises a very small portion of the total current. Further, as the around width B 2 widens, resistances R 2 and R 2 ' decrease. Therefore there is little change in connection hole resistance as a whole. Fig. 3B shows a case where the connection hole 11 deviates in the vertical direction towards the wiring extension side. In this case, around width C 1 narrows and around width C 2 widens. Therefore resistances (R 2 + R 3 ) and (R 2 '+ R 3 ') increase and decrease respectively, thereby cancelling each other, so that the connection hole resistance, as a whole, is only slightly affected. Fig. 3C shows a case where the connection hole 11 deviates towards the wiring extension side. In this case, around width B 2 narrows, and the effective current paths I 2 and I 2 ' narrow, whereby the connection hole resistance inevitably increases. More specifically, current flows through all of resistances r 1 , R 2 and R 3 . As around width B 2 narrows, currents I 2 and I 2 ' flowing through resistances R 2 and R 2 ' decrease, and current il flowing through resistance r 1 , which becomes high due to device structure, increases. Therefore, the matching deviation directly affects the connection hole resistance, and disconnection of the wiring due to heat-emission or electromigration may occur at the notch S. The object of the present invention is to provide a method of selecting widths of margins such that the connection hole resistance does not increase even if matching deviation between a connection hole such as a contact hole or through hole, and a wiring layer occurs. This object is solved as defined in claims 1 and 4. To achieve the above-mentioned object, a matching allowance for the connection hole on the wiring portion side is formed wider than the regular matching allowance by a predetermined width with which a required yield of successful matching can be assured. This invention can be more fully understood from the following detailed description when taken in conjunction with the accompanying drawings, in which: Fig. 1A is a plane view of the wiring pattern of the conventional semiconductor integrated circuit device; Fig. 1B is a cross-sectional view of the above Fig. 1A along the line P-P'; Fig. 2 is an equivalent circuit of the wiring resistance of a wiring near the connection hole such as a contact hole or through hole; Figs. 3A-3C are cross-sectional views of examples of matching deviation between the connection hole and wiring; Fig. 4 is a plane view of a wiring pattern of a semiconductor integrated circuit device according to an embodiment of the present invention; Fig. 5 shows a relationship between the matching deviation amount and the connection hole resistance regarding the conventional semiconductor device and the Fig. 6 is a plan view showing a wiring pattern of a semiconductor integrated circuit according to a second embodiment of the present invention; and Fig. 7 is a plan view showing a wiring pattern of a semiconductor integrated circuit according to a third embodiment of the present invention. A wiring pattern of a semiconductor integrated circuit device according to an embodiment of the present invention will be described with reference to the accompanying drawings wherein like reference numerals designate like items and explanations thereof are omitted. Fig. 4 shows a wiring pattern of a semiconductor integral circuit according to a first embodiment of the present invention, including a semiconductor substrate 21, a connection hole 22, a wiring layer 23, a wiring width A, matching allowances between the connection hole and the wiring layer B and C, a wiring portion P, and a connection portion Q. The connection hole 22 such as a contact hole or a through hole, is formed in the semiconductor substrate 21, and the wiring layer 23 is formed around the connection hole 22. The wiring layer 23 consists of the wiring portion P, which is a wiring portion extending in one direction from a side of the square-shaped connection hole 22, and connection portion Q, which is a wiring portion located adjacent connection hole 22. The matching allowance B on the wiring portion P side of the connection portion Q is formed so that it has a predetermined width, in other words, a width with which a sufficient current path can be obtained when the matching deviation of the wiring layer 23 is set to zero. The matching allowance B on the wiring portion P side is set so that it is a predetermined width wider than the regular matching allowance to cover the necessary matching efficiency. The matching allowance C at the sides other than the wiring portion P side is set to an appropriate width so that the pattern of the wiring layer 23 does not become too large. For example, suppose that the minimum around width of the wiring portion P side for obtaining a sufficient electric current path is about 1.0 micron when the required yield of the successful allowance is 3σ (σ is a value for dispersion in the normal distribution), and the predetermined width with which 3σ can be assured is about 0.5 microns, the allowance B on the wiring portion P side should be set to about 1.5 microns to obtain a sufficient current path. When the matching deviation of the wiring is zero, the around width is about 1.5 microns as originally designed for the width of the matching allowance B. Even if the matching deviation of the wiring is as much as 0.5 microns in the direction opposite to the wiring portion P, the around width of about 1.0 micron can be assured. The matching allowances C for the sides other than the wiring portion P side are set to about 0.7 microns so as to obtain an around width of, for example, about 0.2 microns at a minimum. This is because, if the width of the matching allowances C is set to the same as that of the matching allowance B, the size of the wiring pattern of the wiring layer 23 around the connection hole 22 becomes very large, thereby lowering the degree of integration. The matching allowances other than that of the wiring portion P side should only be set to a minimally necessary width so that the wiring pattern does not become too large. In this embodiment, the wiring width A is set to about 2 microns, and the size of the connection hole is set to about 3.0 x 3.0 microns. According to such a structure, the matching allowance B of the wiring portion P side is set a predetermined width wider than the predetermined allowance so as to cover the matching deviation even in the case where the wiring layer width deviates in the direction opposite to the wiring portion P side. Specifically, even if the wiring layer 23 deviates in the direction opposite to the wiring portion P side, a sufficient around width can be obtained within the range of the successful yield of matching allowance, so that the contact hole resistance is not increased. In the meantime, the connection hole resistance where the wiring layer 23 includes the matching allowance B of about 1.5 microns and the matching allowance C of about 0.7 microns was measured and the result is shown in Fig. 5 as represented by straight line II. As represented by the line II when the amount of deviation in the direction opposite to the wiring portion P side is within 1.0 micron, in other words, the around width is in the range of 0.5-1.5 microns in the wiring layer 23, no increment in the connection hole resistance was detected. Further, the connection hole resistance in the case where the matching allowances for all sides of the connection hole 22 are equally set to about 1.0 micron was measured and the result is also shown in this figure as represented by curve I. The present invention was applied to a bipolar LSI (A/D converter) having 4,500 elements, and no decrement in the degree of integration was detected. Fig. 6 shows a wiring pattern of a semiconductor integrated circuit device according to a second embodiment of the present invention. As shown in this Fig. 6, the connection hole 22, such as a contact hole or a through hole, is formed on the semiconductor substrate 21, and the wiring layer 23 is formed on the connection hole 22. In the wiring layer 23, the wiring portion P and the contact portion Q are connected so that it makes an obtuse angle (π/2< π) therebetween. The first embodiment mentioned above is a case where the wiring portion P and the contact portion Q are connected at right angle. The matching allowance B of the wiring portion P side is formed wider than a predetermined width to ensure a sufficient current path when the matching deviation of matching pattern is set to zero. In detail, the matching allowance B is formed wider than the predetermined matching allowance C by a predetermined width which assures the required yield of successful allowance. For example, suppose that the minimum around width of the wiring portion P side for obtaining a sufficient electric current path is about 1.0 micron. When the required yield of the successful allowance is 3σ (σ is a value for dispersion in the normal distribution), and the predetermined width with which 3σ can be assured is about 0.5 microns, the allowance B on the wiring portion P side should be set to about 1.5 microns to obtain a sufficient current path. Further, the matching allowances other than the wiring portion P side are designed to be about 0.7 microns so as to obtain an around width of, for example, about 0.2 microns at a minimum. with such a structure, when the wiring layer deviates in the direction opposite to the wiring portion P, the around width of the wiring portion P side decreases to the actual matching deviation times sin  (when  = 3π/4, 1/√2) . Therefore, even if the wiring layer 23 is shifted away from wiring portion P, a sufficiently great around width is ensured as long as angle  is determined properly. However, the matching allowance B is, in advance, formed wider than the predetermined matching allowance by a predetermined width with which the actual matching deviation can be covered. Therefore, even if the wiring layer 23 deviates in the direction opposite to the wiring portion P side, the necessary around width can be obtained, and therefore the connection hole resistance does not increase. Lastly, the above-described embodiments include the cases where there is only one wiring portion P. However, the present invention, of course, can be applied to the case where there is more than one wiring portion P, for example, as shown in Fig. 7. In this case also, there will not be any problem if the matching allowances B of each of the wiring portions P is formed wider than a predetermined matching allowance by a width with which a required yield can be ensured. Reference signs in the claims are intended for better understanding and shall not limit the scope.

Claims: A method of forming a wiring pattern in a semiconductor integrated circuit device, said wiring pattern having a connection portion (Q) located on a connection hole (22) and a wiring portion (P) extending from a wiring portion side of said connection portion (Q), comprising the steps of selecting the width of connection portion margins (B,C) between the periphery of said connection portion (Q) to be formed and the periphery of said hole (22) as required to accommodate misalignment of said connection portion with respect to the location of said hole which misalignment may occur at random when forming said connection portion; and forming said connection portion (Q) in and around said hole without filling said hole such that a notch (S) is formed in that portion of said connection portion (Q) which is located in the hole (22), and said wiring portion (P) extending from said hole (22); characterized in that in the step of selecting the width of said connection portion margins the width of the margin (B) on the wiring portion side of said connection portion (Q) is selected larger than the width required for accommodating misalignment that has been selected for the remaining margins (C) of said connection portion (Q); the width of the margin (B) on the wiring portion side of said connection portion (Q) being selected layer by an amount such that when said misalignment in a direction opposite to the wiring portion side occurs, the electrical connection hole resistance will not increase with respect to the electrical connection hole resistance value when there is no misalignment The method according to claim 1, wherein said margin of the wiring portion side has a width about 1.5 microns and said remaining connection portion margins have a width of about 1.0 microns. A method of forming a wiring pattern in a semiconductor integrated circuit device, said wiring pattern having a connection portion (Q) located on a connection hole (22) and a wiring portion (P) having a tapered portion extending from a wiring portion side of said connection portion (Q), comprising the steps of selecting the width of connection portion margins (B,C) between the periphery of said connection portion (Q) to be formed and the periphery of said hole (22) as required to accommodate misalignment of said connection portion with respect to the location of said hole which misalignment may occur at random when forming said connection portion; and forming said connection portion (Q) in and around said hole without filling said hole such that a notch (S) is formed in that portion of said connection portion (Q) which is located in the hole (22), and said wiring portion (P) extending from said hole (22); wherein in the step of selecting the width of said connection portion margins the shortest distance (B) between the periphery of said tapered portion of said wiring portion (P) and the periphery of said hole (22) is selected larger than the width required for accommodating misalignment that has been selected for the remaining margins (C) of said connection portion (Q); Said shortest distance (B) being selected layer by an amount such that when said misalignment in a direction opposite to the wiring portion side occurs, the electrical connection hole resistance will not increase with respect to the electrical hole resistance value when there is no misalignment.

Inventors: ABE MASAHIRO, MASE YASUKAZU, YAMAMOTO TOMIE, ABE, MASAHIRO, MASE, YASUKAZU, YAMAMOTO, TOMIE, ABE, MASAHIRO, C/O INTELLECTUAL PROPERTY DIVISION, MASE, YASUKAZU, C/O INTELLECTUAL PROPERTY DIVISION, YAMAMOTO, TOMIE, C/O INTELLECTUAL PROPERTY DIV.
Applicants: TOSHIBA KK, KABUSHIKI KAISHA TOSHIBA
Application year: 1990
Main classification: H01L23
IPC codes: H01L23, H01L21