Semiconductor device having an interconnecting circuit board and method for manufacturing same

Abstract: A semiconductor device having an interconnecting circuit board comprises an island (20) formed in a predetermined plane, a semiconductor chip (21) disposed on the island (20) and having a plurality of electrically connecting electrode pads (22), an interconnecting circuit board (23) disposed on the semiconductor chip (20) and having an electrically conductive pattern (27), a plurality of inner leads (25) disposed around the island (20), a first electrically connecting wire (26c) connecting the electrically conductive pattern (27) and one (22b) of the plurality of electrically connecting electrode pads (22), and a second electrically connecting wire (26a,26b) connecting the electrically conductive pattern (27) and one (25a) of the inner leads (25).

Description: The present invention relates to a semiconductor device and more particularly to a semiconductor device having an interconnecting circuit board and a method of manufacturing such a semiconductor device. Fig. 1 illustrates a top view of a semiconductor device 8 comprising a multichip conventional integrated circuit having a plurality of bipolar transistors. Two semiconductor chips 10a and 10b are disposed on an island 11 of electrically conductive material which is connected to a lead frame by four support pins 12. Several inner leads 13 are disposed around island 11. A plurality of bonding wires 16 provide interconnecting functions. A circuit board 14 is disposed between semiconductor chips 10a and 10b and on island 11. A plurality of electrically conductive electrode pads 15 are disposed about the perimeter of semiconductor chips 10a and 10b and on circuit board 14. Bonding wires 16a are each electrically connected between one of pads 15 and an adjacent one of inner leads 13. Other bonding wires 16b are each electrically connected between one of the pads 15 on chips 10a and 10b facing circuit board 14 and one of the pads 15 on circuit board 14. Bonding wires 16a and 16b need to be short and should avoid touching undesired components. Thus bonding wires 16a and 16b are electrically connected to only neighboring portions of chips 10a, 10b and board 14. Island 11, semiconductor chips 10a and 10b, circuit board 14, support pins 12, bonding wires 16a and 16b, and inner leads 13 are encapsulated by molded resin or encapsulated by a ceramic package. However, in a conventional semiconductor device 8 as shown in Fig. 1, if there is need for electrically connecting an inner lead 13a which is disposed on the left side of Fig. 1 and an electrode pad 15a which is disposed on the right side of semiconductor chip 10b, a long bonding wire 16 is needed. However, a long bonding wire may connect undesired components, so that desired circuit functions may be disturbed. Therefore, long connections between one of the inner leads and one of the electrically connecting electrode pads are not achieved. Thus, in such conventional techniques, inner circuit elements of the semiconductor chips are designed such that there is no need to electrically connect the distant circuit elements. Moreover, the inner circuit elements of the semiconductor chips 10a and 10b must be redesigned frequently in order to accommodate placement of inner leads. An insulating film formed on a semiconductor chip having a wiring pattern and pads for interconnection with the chip and the bonding wires or leads is known from Patents Abstracts of Japan 15 (026), (E-1025), JP-A-2271548. A power circuit pattern and a grounded circuit pattern formed on an insulating film disposed on a plurality of leads for interconnecting a semiconductor element and a small number of the leads is disclosed in Patent Abstracts of Japan 13 (346), (E-798), JP-A-1106436. A plurality of chips mounted on a lead frame are relayed and connected by the lead frame is disclosed in Patent Abstracts of Japan 15 (070), (E-103), JP-A-2294061. It is accordingly an object of the present invention to provide an improved semiconductor device which enables electrical connection between an electrically connecting electrode pad and an inner lead each disposed in distant portions without redesigning the inner circuitry of the semiconductor chip. It is another object to provide a method of fabricating the improved semiconductor device. According to a first aspect of the present invention there is provided a semiconductor device, comprising: an island; a first semiconductor chip disposed on the island; and a plurality of inner leads disposed around the island and the first semiconductor chip; a first circuit board having a first electrically conductive pattern, the first circuit board being disposed on the semiconductor chip; wherein said device further comprises a second circuit board having a second electrically conductive pattern thereon, the second circuit board being disposed on the plurality of the inner leads; means for providing selective electrical interconnection between the first semiconductor chip, the first circuit board, the second circuit board, and the plurality of inner leads, wherein the first circuit board and the second circuit board comprise an integrally formed unitary structure. According to a second aspect of the present invention, there is provided a method of manufacturing a semiconductor device, the method comprising the steps of: forming an island and a lead frame having a plurality of inner leads of conductive material; forming a unitary interconnecting circuit board structure having a first circuit board and a second circuit board; forming a first electrically connecting pattern and a plurality of electrode pads on the first circuit board; forming a second electrically connecting pattern on the second circuit board; mounting the first circuit board on a semiconductor chip having a desired electrical function and having a plurality of electrode pads thereon; mounting the chip on the island; mounting the second circuit board on the inner leads; forming an electrically connecting means between one of the inner leads and one of the electrode pads on the chip; forming an electrically connecting means between another of the inner leads and the first electrically connecting pattern; forming an electrically connecting means between the first electrically connecting pattern and another of the electrode pads on the chip; forming an electrically connecting means between another of the inner leads and the second electrically connecting pattern; and forming an electrically connecting means between the second electrically connecting pattern and a further one of the electrode pads on the chip. With the semiconductor device of the present invention, electrical connections between a desired inner lead and a desired electrode pad on the chip can be made by an interconnecting circuit board. Other objects, features, and advantages of the present invention will become apparent from the followed detailed description. Fig. 1 is top view of a conventional semiconductor device having multiple semiconductor chips; Fig. 2a is a top view of a first example, useful for the understanding of the invention, of a semiconductor device having a single semiconductor chip; Fig. 2b is a sectional view of the semiconductor device shown in Fig. 2a; Fig. 3a is a top view of a second example, useful for the understanding of the invention, of a semiconductor device having a single semiconductor chip; Fig. 3b is a sectional view of the semiconductor device shown in Fig. 3a; Fig. 4a is a top view of a third example, useful for the understanding of the invention, of a semiconductor device having a single semiconductor chip; Fig. 4b is a sectional view of the semiconductor device shown in Fig. 4a; Fig. 5a is a top view of a fourth, fifth and sixth example, useful for the understanding of the invention, of a semiconductor device, having multiple semiconductor chips; Fig. 5b is a sectional view of the semiconductor device shown in Fig. 5a; Fig. 6a is a top view of a semiconductor device of a first embodiment of this invention, having a single semiconductor chip; Fig. 6b is a sectional view of the semiconductor device shown in Fig. 6a; Fig. 7a is a top view of a semiconductor device of a second embodiment of this invention, having a single semiconductor chip; Fig. 7b is a sectional view of the semiconductor device shown in Fig. 7a; Fig. 8a is a top view of a semiconductor device of a third embodiment of this invention, having a single semiconductor chip; Fig. 8b is a sectional view of the semiconductor device shown in Fig. 8a; Fig. 9a is a top view of a semiconductor device of a fourth embodiment of this invention, having multiple semiconductor chips; Fig. 9b is a sectional view of the semiconductor device shown in Fig. 9a; Fig. 10a is a top view of a seventh example, useful for the understanding of the invention, of a semiconductor device, having multiple semiconductor chips; Fig. 10b is a sectional view of the semiconductor device shown in Fig. 10a; Figs. 11a-11i are sectional views showing steps in a first preferred method for manufacturing a semiconductor device in accordance with the invention; and Figs. 12a-12i are sectional views showing steps in a method useful for the understanding of the invention, for manufacturing a semiconductor device. A first example, useful for the understanding of the invention, is shown in Fig. 2a and Fig. 2b. A semiconductor device includes an island 20 of electrically conductive material shaped to a flat plane. A semiconductor chip 21 is disposed on a center part of island 20, and includes a plurality of electrically connecting electrode pads 22 for accepting an input signal and supplying an output signal. An interconnecting circuit board 23 is disposed on semiconductor chip 21. Interconnecting circuit board 23 and semiconductor chip 21 are mechanically connected by bonding, e.g., by paste or glue. Island 21 is supported by four support pins 24, whereby island 21 is connected to a lead frame (not shown in Figs. 2a and 2b). A plurality of inner leads 25 are disposed around island 20. A plurality of bonding wires 26 connect electrically conducting electrode pads 22 and neighbor inner leads 25. Interconnecting circuit board 23 includes an electrically conductive pattern 27 and electrically connecting electrode pads, e.g., a first electrically connecting electrode pad 28a and a second electrically connecting electrode pad 28b connected to connecting pattern 27. Interconnecting circuit board 23 is made of glass epoxy or polyimide and electrically conductive pattern 27 is made of copper. A first inner lead 25a as shown in the right side of Fig. 2a and a first pad 22a, as shown right side of Fig. 2a are connected by a first wire 26a. A first pad 28a on the interconnecting circuit board 23 and the first pad 22a are connected by a second wire 26b. A second electrically connecting electrode pad 28b as shown on the left side of Fig. 2a and a second pad 22b as shown on the left side of Fig. 2a are connected by a third wire 26c. Thus, first inner lead 25a and a second pad 22b become electrically connected. Pattern 27 may have an electrical resistance or capacitance. Electrically connecting electrode pads 22 and 28 may be made of nickel, copper, or gold. These elements as described above are encapsulated by resin or ceramic 29, as shown in Fig. 2b. As a result, a first inner lead and a second electrically connecting electrode pad which is spaced from the first inner lead can be electrically connected by using interconnecting circuit board 23. As shown in Fig. 2b, interconnecting circuit board 23 is disposed on semiconductor chip 21, and not disposed beside chip 21. Thus, there is no need for additional space on island 20 to support interconnecting circuit board 23, thereby permitting a wise reduction of island 20. A second example, useful for the understanding of the invention is shown in Figs. 3a and 3b, and includes an interconnecting circuit board disposed on a semiconductor chip, as in the first embodiment, plus an interconnecting circuit board disposed on the inner leads. An island 30 is shaped to a flat plane. A semiconductor chip 31, having a plurality of electrically connecting electrode pads 32, is disposed on the island 30. Pads 32 accept an input signal and supply an output signal. A plurality of inner leads 34 are disposed around the island 30. An interconnecting circuit board 33 having an electrically conductive pattern 37 entirely surrounding semiconductor chip 31 is disposed on the plurality of inner leads 34 and surrounds semiconductor chip 31. A plurality of electrically connecting means 36 such as wires or bonding tapes are connected between electrically conductive pattern 37 and one of the electrically connecting electrode pads 32 on chip 31 and between pattern 37 and one of inner leads 34. Interconnecting circuit board 33 and inner leads 34 are mechanically connected by bonding, e.g., by paste or glue. Island 31 is supported by four support pins 35, whereby the island 30 is connected to a lead frame (not shown in Figs. 3a and 3b). A first inner lead 34a as shown on the right side of Fig. 3a and a first pad 32a as shown on the right side of Fig. 3a are connected by a first wire 36a. A first portion of a first inner lead 34a and electrically conductive pattern 37 of interconnecting circuit board 33 are connected by a second wire 36b. A second electrically connecting pad 32b as shown on the left side of Fig. 3a and a second adjacent portion of electrically conductive pattern 37 on the interconnecting circuit board 33 are connected by a third wire 36c. Thus, first inner lead 34a and a second pad 32b which are disposed apart from each other, may become electrically connected. Electrically conductive pattern 37 may have an electrical resistance or capacitance. These elements as described above are encapsulated by resin or ceramic 39 as shown in Fig. 3b. The device of the second example uses the same material as above described of the first example. As a result, a first inner lead 34a and second electrically connecting electrode pad 32b which is spaced from the first inner lead 34a can be electrically connected by using interconnecting circuit board 33. Because electrically conductive pattern 37 entirely surrounds chip 31, each pad can connect to any of inner leads 34. Also, as shown in Fig. 3b, since interconnecting circuit board 33 is disposed on inner leads 34 and not disposed beside chip 31 on island 30, there is no need for space on island 30 to dispose the interconnecting circuit board 33, so size reduction of island 30 may be achieved. This device has the advantage of strengthening the inner leads against over pressure, because the middle of the inner leads are connected to each other by interconnecting circuit board 33 made of glass epoxy or polyimide. A third example, useful for the understanding of the invention, is shown as Fig. 4a and Fig. 4b, and includes both an interconnecting circuit board on the semiconductor chip and an interconnecting circuit board on the inner leads. As seen in Figs. 4a and 4b, an island 40 is shaped to a predetermined plane and is supported by four support pins 44, whereby the island 40 is connected to a lead frame (not shown). A semiconductor chip 41, having a plurality of electrically connecting electrode pads 42, is disposed on the island 40. Pads 42 accept an input signal or supply an output signal. A plurality of inner leads 45 is disposed around island 40 and semiconductor chip 41. A first interconnecting circuit board 43 having a first electrically conductive pattern 47 and a plurality of electrically connecting electrode pads 48 connected to pattern 47 is disposed on semiconductor chip 41. First electrically connecting means 46b, 46c, such as wires or bonding tape, connect one of electrically connecting electrode pads 42 and either electrically conductive pattern 47 or a first one of the inner leads 45. A second interconnecting circuit board 49 having a second electrically conductive pattern 50 partly surrounds the semiconductor chip 41, and is disposed on the plurality of the inner leads 45. Second interconnecting circuit board 49 and inner leads 45 are mechanically connected by bonding, e.g., by paste or glue. A second electrically connecting means 46e, 46d connects the second electrically conductive pattern 50 and a second one of the electrically connecting electrode pads 42c or a second one of the inner leads 45. Also, first interconnecting circuit board 43 and the semiconductor chip 41 are mechanically connected by bonding, e.g., by paste or glue. A first inner lead 45a, shown on the left side in Fig. 4a, and a first pad 42a, shown on the left side in Fig. 4a, are connected by a first wire 46a. A first electrically connecting electrode pad 48a on interconnecting circuit board 43, adjacent first pad 42a, and the first pad 42a are connected by a second wire 46b. A second pad 48b on the first interconnecting board 47 and a neighboring second pad 42b on chip 41 as shown right side in Fig. 4a is connected by a third wire 46c. Thus, even though widely separated, first lead 45a and second pad 42b become electrically connected. Note that chip 41 includes a plurality of pads 42 each corresponding to one of leads 45, and further includes at least one additional pad 42b which does not correspond to an inner lead 45. A second inner lead 45b as shown in Fig. 4a and a first portion of electrically conductive pattern 50 on second interconnecting circuit board 49, adjacent to second lead 45b, is connected by a fourth wire 46d. A third pad 42c on chip 41 and a second portion of the electrically conductive pattern 50 adjacent third pad 42c on second interconnecting circuit board 49 are connected by fourth wire 46e. First electrically conductive pattern 47 and second electrically conductive pattern 50 may have an electrical resistance or capacitance. These elements as described above are encapsulated by resin or ceramic 51 as shown in Fig. 4b. The device of the third example uses same material as described above with respect to the first example. As a result, a first inner lead 45a and a second electrically connecting electrode pad 42b which is spaced from the first inner lead 45a can be electrically connected using the first interconnecting circuit board 43, and second inner lead 45b and third electrically connecting electrode pad 42c which is spaced from the second inner lead 45b can be electrically connected using the second interconnecting circuit board 49. Electrically conductive pattern 50 may either entirely surround chip 41 or partly surround chip 41. As shown in Fig. 4b, interconnecting circuit boards 43 and 49 are respectively disposed on chip 41 or on inner leads 45, and not disposed beside the chip 41. Thus, there is no need for space on island 40 to dispose the interconnecting circuit board 43, 49, thereby achieving a size reduction of the island 40. A fourth example, useful for the understanding of the invention, is shown as Fig. 5a and Fig. 5b. Fig. 5b shows a side view of the semiconductor device of Fig. 5a in a direction of arrow A in Fig.5a. A semiconductor device having an interconnecting circuit board comprises an island 60 shaped to predetermined plane, a first semiconductor chip 61 having a plurality of electrically connecting electrode pads 62 and disposed on island 60, and a first interconnecting circuit board 63 having an electrically conductive pattern 64. Board 63 has a plurality of electrically connecting electrode pads 65 (65a and 65b) which are connected to pattern 64. A second semiconductor chip 66 has a plurality of electrically connecting electrode pads 67 and is disposed on island 60. A second interconnecting circuit board 68 is disposed on second semiconductor chip 66 and has an electrically conductive pattern 69 with a plurality of electrically connecting electrode pads 70 (70a and 70b) connected to electrically conductive pattern 69. An electric connecting circuit board 71 has a plurality of electrically connecting electrode pads 72 and an electrically conductive pattern 73 connected to pads 72. Circuit board 71 is disposed on island 60 between chips 61 and 66. Circuit board 71 is made of glass, epoxy or polyimide. A plurality of inner leads 74 is disposed around the island 60. A first electrically connecting means, e.g., wire 75a, connects the first one 74a of the inner leads and the first one 62a of the electrically connecting electrode pads on first semiconductor chip 61. A second electrically connecting means, e.g., wire 75b, connects a second one 74b of the inner leads and a first one 65a of the electrically connecting electrode pads on first interconnecting circuit board 63. A third electrically connecting means, e.g., wire 75c, connects a third one 74c of the inner leads and a first one 72a of the electrically connecting electrode pads on the circuit board 71. A fourth electrically connecting means, e.g., wire 75d, connects a second one 62b of electrically connecting electrode pads on first semiconductor chip 61 and a second one 72b of the electrically connecting electrode pads on circuit board 71. A fifth electrically connecting means, e.g., wire 75e, connects a second one 65b of the electrically connecting electrode pads on first interconnecting circuit board 63 and a third one 72c of the electrically connecting electrode pads on the circuit board 71. A sixth electrically connecting means, e.g., wire 75f, connects a fourth electrically connecting electrode pad 72d on circuit board 71 and a first one 67a of the electrically connecting electrode pads on second chip 66. A seventh electrically connecting means, e.g., wire 75g, connects a fifth one 72e of the electrically connecting electrode pads on the electric connecting circuit board 71 and a first one 70a of the electrically connecting electrode pads on second interconnecting circuit board 68. An eighth electrically connecting means, e.g., wire 75h, connects a second one 70b of the electrically connecting electrode pads on second interconnecting circuit board 68 and a second one 67b of the electrically connecting electrode pads on second chip 66. A ninth electrically connecting means, e.g., wire 75i, connects a third one 67c of the electrically connecting electrode pads on the second chip 66 and a fourth one 74d of the inner leads. Semiconductor chips 61 and 66 are disposed on island 60, and have a plurality of electrically connecting electrode pads 62, 67, respectively, for accepting an input signal and outputting an output signal. Interconnecting circuit boards 63 and 68 and semiconductor chips 61 and 66 are mechanically connected by bonding, e.g., by paste or glue. Island 60 is supported by four support pins 76 at four corners, whereby the island 60 is connected to a lead frame (not shown). Each electrical pattern 64, 69, 73 may have an electrical resistance or capacitance. These elements as described above are encapsulated by resin or ceramic 77 as shown in Fig. 5b. The device of the fourth example uses same material as described with respect to the first example. As a result, second inner lead 74b and second electrically connecting electrode pad 67b on the second chip 66 which is spaced from the second inner lead 74b are connected using first interconnecting circuit board 63, the circuit board 71, and second interconnecting circuit board 68. Although the device shown in Figs. 5a and 5b includes off-chip interconnect board 71, certain applications may not require board 71, and electrical connections may be made directly between pads 62 and 67 of chips 61 and 66. Also, direct electrical connection between boards 63 and 68 may be made. As shown in Fig. 5b, interconnecting circuit boards 63 and 68 are respectively disposed on chips 61 and 66, and are not disposed beside chips 61 and 66. Thus, there is no need for space on island 60 to dispose the interconnecting circuit boards 63 and 68, and a reduction in the size of island 60 may be achieved. A fifth example, useful for the understanding of the invention is also shown in Fig. 5a and 5b. The fifth example comprises a semiconductor device having all elements of the device described above and further comprising a third interconnecting circuit board 80 having electrically connecting circuit pattern 81 entirely surrounding island 60. This device also includes a tenth connecting means, e.g. wire 75j, for connecting a fifth inner lead 74e and a first portion 81a of electrically conductive pattern 81, and an eleventh electrically connecting means, e.g., wire 75k for connecting a second portion 81b and a fourth electrically connecting electrode pad 67d. Thus, fifth inner lead 74e and the fourth pad 67d become electrically connected even though they are physically separated. Interconnecting circuit board 80 and the inner leads are mechanically connected by appropriate bonding techniques, e.g., using paste or glue. Electrically conductive pattern 81 may have an electrical resistance or capacitance. These elements as described above are encapsulated by resin or ceramic 77, as shown in Fig. 5b. As shown in Fig. 5b, all of the interconnecting circuit boards 63, 68, 80 are disposed on chips 61, 66, or on inner leads 74, and are not disposed beside the chips 61, 66 on the island 60. Thus, there is no need for space on the island 60 to dispose interconnecting circuit boards 63, 68, 80, and a reduction in the size of island 60 may be achieved. A sixth example, useful for the understanding of the invention, is also shown in Fig. 5a and Fig. 5b. This device excludes first interconnecting circuit board 63 and second interconnecting circuit board 68 of the device described above. This device has the same merits as the previous device, excluding the merits of the first interconnecting circuit board 63 and the second interconnecting circuit board 68. Other variations of devices having multiple semiconductor chips are available. For example, circuit board 71 may be excluded from the device. In that case, pads of chips 61, 66 which face each other are connected directly by wires without using circuit board 71. Thus, even greater size reductions of island 60 may be achieved. Also, board 80 may only partially surround island 60. Although the example shown in Figs. 5a and 5b include only two chips, additional chips, including corresponding electrical interconnections, may, of course, be employed in appropriate applications. A first embodiment of the invention is shown as Fig. 6a and Fig. 6b. It comprises an island 90 formed in a predetermined plane, and a semiconductor chip 91 disposed on island 90 having a plurality of electrically connecting electrode pads 99. A plurality of inner leads 92 is disposed around island 90. A first interconnecting circuit board 93 is disposed on chip 91 having an electrically conductive pattern 94 and a plurality of electrically connecting pads 95 connected to the electrically conductive pattern 94. A second interconnecting circuit board 96 is disposed on inner leads 92 and has an electrically conductive pattern 97 on the upper side thereof. Connecting pattern 97 can be the same as pattern 50 in the third example, shown in Figs. 4a and 4b. A difference between this device and the third example is that island 90 of Figs. 6a and 6b is depressed below the plane of inner leads 92. First interconnecting circuit board 93 and second interconnecting board 96 are mechanically connected by support pins 98 and are formed on the same plane. Pads on chip 91 and a tip of inner leads 92 are exposed in the opening between interconnecting circuit board 93 and interconnecting structure 96. The device of the first embodiment has first advantage of strengthening the structure of second interconnecting board 96, because interconnecting board 93 and interconnect board 96 are in the same plane and are respectively supported by chip 91 and support pin 98. A second advantage of this device is that tape automated bonding (TAB) may be employed for connecting between the desired electrically connecting pads 95 on the circuit board 93 and the desired inner lead 92, because the two connecting portions are disposed on the same plane. The TAB material is formed of a copper lead for providing the functions of electrical connection and polyimide tape connected to one side of the copper lead for providing the function of mechanical support. The use of TAB has the advantage of permitting reduction in spacing between the pads on chip 91. A second embodiment of the invention is shown as Fig. 7a and Fig. 7b. It comprises an island 100, a semiconductor chip 101 disposed on island 100 and having a plurality of electrically connecting electrode pads 102, a plurality of inner leads 103 around island 100, a first interconnecting circuit board 104 disposed on chip 101 and having an electrically conductive pattern 105 and a plurality of electrically connecting pads 106 connected to pattern 105, and a second interconnecting circuit board 107 disposed on the inner leads 103. Second interconnecting circuit board 107 has an electrically conductive pattern 108 on its upper side. Island 100 is supported by support pins 109, and is connected to a lead frame (not shown). Connecting pattern 105 can be the same as in the first embodiment. A difference between this device and the first embodiment is that island 100 is depressed from the inner leads 103, and first interconnecting circuit board 104 and second interconnecting circuit board 107 are integrally formed in a unitary structure and are coplanar with one another. Island 100 and the tips of inner leads 103 are both entirely covered by either the first interconnecting circuit board 104 or second interconnecting current board 107. A difference between this device and that of the first embodiment is connections 150 between pads 102 on the chip 101 and inner leads 103, and connections 152 between pads 106 on first interconnecting circuit board 104 and inner leads 103, which connections pass over interconnecting circuit board 107. A third embodiment of the invention is shown as Fig. 8a and Fig. 8b. It comprises essentially the same elements as the device described above. However, connections between pads 102 on chip 101 and the inner leads 103 are provided by TABs 110, and interconnecting circuit board 107 is not mechanically connected to chip 101. Interconnecting circuit board 107 is separated from inner lead 103 by TAB 110, such that the under plane of interconnecting circuit board 107 is higher than upper plane of inner leads 103 by the thickness of TABs 110. A fourth embodiment of the invention is shown in Figs. 9a and 9b. This device comprises essentially the same elements as the device, shown in Figs. 5a and 5b. However, a first interconnecting circuit board 111, a second interconnecting circuit board 112, and a third interconnecting circuit board 113 are mechanically connected to each other by support pins 76 and have coplanar lower surfaces. An island 114 is depressed from inner leads 74. The device of the fourth embodiment has an advantage of strengthening of structure of second interconnecting circuit board 113, because two interconnecting boards are connected by support pins 76. A second advantage of this device is that tape-automated bonding (TAB) may be used for connecting between desired electrically connecting pads on the chip and the desired inner lead 74, because the two connected portions are disposed in the same plane. The TAB material is formed from copper lead providing the functions of electrical connection, and polyimide tape connected to one side of the copper lead for providing mechanical support. The use of TAB has the advantage of reducing the interval or spacing of the pads on the chip. A seventh example, useful for the understanding of the invention, is shown in Figs. 10a and 10b. This device comprises essentially the same elements as the device, shown in Figs. 5a and 5b. However, a connecting circuit board 120 and a surrounding interconnecting circuit board 121 are mechanically connected to each other by support pins 160. Also, circuit boards 120 and 121 have coplanar lower surfaces, and are integrally formed as a unitary structure. Further, island 60 is not depressed from inner leads 74. This device has the advantage of strengthening the structure of the interconnecting circuit board 121, because interconnecting circuit board 121 is connected to circuit board 120. Figs. 11a through 11i illustrate a preferred method of manufacturing a semiconductor device of the first embodiment in accordance with the invention. In a first step, as shown in Fig. 11a, a lead frame having a plurality of inner leads 130 is provided. An island 131 is formed by depressing a portion of the lead frame. Island 131 is connected to the remainder of the lead frame by a plurality support pins 132. In a second step, as shown in Fig. 11b, a unitary interconnecting circuit board structure is formed, which includes a center part 133a and an outer part 133b connected by a support pin (not shown). An opening 133c is formed between parts 133a and 133b. A first electrical connecting pattern 134a is formed on the center part 133a and a plurality of electrical connecting electrode pads 135 are formed on center part 133a. A second electrically conductive pattern 134b is formed on the outer part 133b. In a third step, as shown in Fig. 11c, a semiconductor chip 136 having a desired electrical function and a plurality of electrically connecting electrode pads 137 is mounted on island 131, whereby chip 136 and island 131 are physically connected. In a fourth step, as shown in Fig. 11d, center part 133a is mounted on chip 136, and outer part 133b is mounted on inner leads 130. Any appropriate mounting technique, such as gluing or bonding may be employed. In a fifth step, as shown in Fig. 11e, a first inner lead 130a and first electrically connecting electrode pad 137a on chip 136 are connected with an electrically conductive material, e.g., wire on TAB 138. In a sixth step, as shown in Fig. 11f, a second inner lead 130b (hidden by lead 130a in Fig. 11f) and a first electrically connecting electrode pad 135a on the interconnecting circuit board 133a on chip 136 are connected with similar electrically conductive material 139. In a seventh step, as shown in Fig. 11g, a second electrically connecting electrode pad 135b on center part 133a of the interconnecting circuit board and a second electrically connecting electrode pad 137b on chip 136 with electrically conductive material, e.g., wire 170. In an eleventh step, as shown in Fig. 11h, a third inner lead 130c and electrically conductive pattern 134b on the outer part 133b of the interconnecting circuit board are connected with electrically conductive material, e.g., wire 140. In a twelfth step, as shown Fig. 11i, electrically conductive pattern 134b on the interconnecting circuit board 133b on the inner lead 130c and a third electrically connecting electrode pad 137c as on chip 136 are connected with wire 141. An advantage of this method is that the step of connecting the interconnecting circuit board 133a and interconnect structure 133b to the chip 136 and the inner lead 130 is simultaneously performed. Thus, the number of manufacturing steps of the semiconductor device is reduced. Another advantage is that interconnections can be performed on two portions which are located apart in the vertical direction. Because the step of connecting to the lower portion is performed first, and the step of connection to the higher portion is performed second, the two connection means are not in contact with each other. This method of manufacturing a semiconductor device is available for semiconductor devices having other structures, e.g., the first to fourth embodiments described above. Figs. 12a-12j illustrate a method, which is an example for understanding the invention, for manufacturing the semiconductor device of Figs. 4a and 4b. In a first step as shown in Fig. 12a, an island 40 and a lead frame having a plurality of inner leads 45 are formed of conductive material. Island 40 is connected to the lead frame via support pins 44. In a second step, as shown in Fig. 12b, a first interconnecting circuit board 43 is formed having a first electrically connecting pattern 47 and a plurality of electrically connecting electrode pads 48a, 48b. In a third step, as shown in Fig. 12c, a second interconnecting circuit board 49 is formed having a second electrically connecting pattern 50 disposed thereon. In a fourth step, as shown in Fig. 12d, first interconnecting circuit board 43 is mounted on a semiconductor chip 41 having a desired electrical function and having a plurality of electrically connecting electrode pads 42. First interconnecting circuit board 43 is mounted to chip 41 by suitable means, such as bonding with paste or glue. In a fifth step, as shown in Fig. 12e, chip 41 is mounted to island 40 by suitable means, such as bonding with paste or glue. In a sixth step, as shown in Fig. 12f, second interconnecting circuit board 49 is mounted on inner leads 45. In a seventh step, as shown in Fig. 12g, an electrically connecting means such as a wire 46a is formed between an inner lead 45a and an electrically connecting electrode pad 42a on chip 41, and an electrically connecting means 46 is formed between another inner lead 45b and an electrode pad 42b. In a eighth step, as shown in Fig. 12h, an electrically connecting means 46e is formed between electrically connecting electrode pad 42b and one portion of second electrical connecting pattern 50. In a ninth step, as shown in Fig. 12i, an electrically connecting means 46b is formed connecting a pad 42a on chip 41 and a pad 48a on first pattern 47, and an electrically connecting means 46c is formed between pad 42b and a pad 48b. In a tenth step, as shown in Fig. 12j, an electrically connecting means, for example, wire 46d, is formed between inner lead 45 and second electrically connecting pattern 50 on second interconnecting circuit board 49. The method described above provides the ability to connect two portions of the semiconductor device which are vertically separated. Since the step of connecting the lower portions preferably is performed first and the step of connecting the upper portions preferably is performed later, undesired connections between the connecting means are avoided. Numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the present invention can be practiced in a manner other than as specifically described herein.

Claims: A semiconductor device, comprising: an island (90, 100, 114, 131); a first semiconductor chip (91. 101, 61, 136) disposed on the island (90, 100, 114, 131); and a plurality of inner leads (92, 103, 74, 130) disposed around the island (90, 100, 114, 131) and the first semiconductor chip (91, 101, 61, 136); a first circuit board (93, 104, 111, 133a) having a first electrically conductive pattern (194, 105, 64, 134a) thereon, the first circuit board (93, 104, 111, 133a) being disposed on the first semiconductor chip (91, 101, 61, 131); characterised in that said device further comprises a second circuit board (96, 107, 113, 133b) having a second electrically conductive pattern (97, 108, 81, 134b) thereon, the second circuit board (96, 107, 113, 133b) being disposed on the plurality of the inner leads (92, 103, 74, 130); means for providing selective electrical interconnection between the first semiconductor chip (91, 101, 61, 136), the first circuit board (93, 104, 111, 133a), the second circuit board (96, 107, 113, 133b), and the plurality of inner leads (92, 103, 74, 130), wherein the first circuit board (93, 104, 111, 133a) and the second circuit board (96, 107, 113, 133b), comprise an integrally formed unitary structure. A semiconductor device, according to claim 1, further comprising: a second semiconductor chip (66) disposed on the island (114); a third interconnecting circuit board (112) having an third electrically conductive pattern thereon, and being disposed on the second semiconductor chip (66); a fourth circuit board (71) having thereon a fourth electrically conductive pattern (73) connected to a plurality of electrode pads (72), the fourth circuit board (71) being disposed on the island (114) and between the first semiconductor chip (61) and the second semiconductor chip (66); and means (75) for providing selective electrical interconnection between the first and second chips (61, 66), the first, second, third and fourth circuit boards, and the plurality of inner leads (74). A semiconductor device according to claim 1 or 2, wherein the means for providing selective electrical interconnection comprises means (110), passing under the second circuit board (107), for electrically connecting the chip (101) and the inner leads (103). A semiconductor device according to claim 1 or 2, wherein the means for providing selective electrical interconnection comprises means (150), passing over the second circuit board, for electrically connecting the chip and the inner leads. A semiconductor device according to claim 1, wherein: the island (114) is formed in a predetermined plane; the first semiconductor chip (61) has a plurality of electrode pads (62) thereon; and the means for providing selective electrical interconnection comprises: a first electrically connecting means (75b) for connecting the first electrically conductive pattern (64) and a first one of the inner leads (74); a second electrically connecting means (75n) for connecting the first electrically conductive pattern (64) and a first one of the electrode pads (62); a third electrically connecting means (75k) for connecting the second electrically conductive pattern (81) and a second one (67d) of the electrode pads (62); and a fourth electrically connecting means (75j) for connecting the second electrically conductive pattern (81) and a second one (74e) of the inner leads (74). A semiconductor device according to claim 5, wherein the number of electrode pads is greater than the number of inner leads. A semiconductor device according to claim 2, wherein: the first semiconductor chip (61) has a plurality of electrode pads (62) thereon; and the second semiconductor chip (66) has a plurality of electrode pads (67) thereon; the first circuit board (63) has a plurality of electrode pads (65) connected to the first electrically conductive pattern (64); the third circuit board (68) has a plurality of electrode pads (70a, 70b) connected to the third electrically conductive pattern (69); the semiconductor device further comprising; a first electrically connecting means (75b) for connecting a first one (74b) of the inner leads (74) and a first one (65a) of the electrode pads (65) on the first circuit board (63); a second electrically connecting means (75n) for connecting a first one of the electrode pads (62) on the first chip (61) and a second one of the electrode pads (65) on the first circuit board (63); a third electrically connecting means (75k) for connecting a first one (67d) of the electrode pads (67) on the second chip (66) and the electrically conductive pattern (81) on the second circuit board (80); a fourth electrically connecting means (75j) for connecting a second one (74e) of the inner leads (74) and the electrically conductive pattern (81) on the second circuit board (80); a fifth electrically connecting means (75a) for connecting a third one (74a) of the inner leads (74) and a second one (62a) of the electrode pads (62) on the first chip (61); a sixth electrically connecting means (75c) for connecting a fourth one (74c) of the inner leads (74) and a first one (72a) of the electrode pads (72) on the fourth circuit board (71); a seventh electrically connecting means (75d) for connecting a third one (62b) of the electrode pads (62) on the first chip (61) and a second one (72b) of the electrode pads (72) on the fourth circuit board (71); an eighth electrically connecting means (75e) for connecting a third one (65d) of the electrode pads (65) on the first circuit board (63) and a third one (72c) of the electrode pads (72) on the fourth circuit board (71); a ninth electrically connecting means (75f) for connecting a fourth one (72d) of the electrode pads (92) on the fourth circuit board (71) and a second one (67a) of the electrode pads (67) on the second chip (66); a tenth electrically connecting means (75g) for connecting a fifth one (72e) of the electrode pads (72) on the fourth circuit board (71) and a first one (70a) of the electrode pads (70a, 70b) on the third circuit board (68); an eleventh electrically connecting means (75h) for connecting a second one (70b) of the electrode pads (70a, 70b) on the third circuit board (68) and a third one (67b) of the electrode pads (67) on the second chip (66); and a twelfth electrically connecting means (75i) for connecting a fourth one (67c) of the electrode pads (69) on the second chip (66) and a fifth one (74d) of the inner leads (74). A semiconductor device according to claim 5 or 7, wherein the first, second and third circuit boards (63, 80, 68) are coplanar. A semiconductor device according to claim 5 or 7, wherein the semiconductor device further comprises means (110), passing under the second circuit board (80) on the inner leads (74) for electrically connecting electrode pads on the first and second semiconductor chips (61, 66) and the inner leads (74). A semiconductor device according to claim 5 or 7, wherein the semiconductor device comprises means (150) passing over the second circuit board (80) on the inner leads (74), for electrically connecting electrode pads (62, 87) on the first and second semiconductor chips (61, 66) and the inner leads (74). A method of manufacturing a semiconductor device, the method comprising the steps of: forming an island (131) and a lead frame having a plurality of inner leads (130) of conductive material; forming a unitary interconnecting circuit board structure (43) having a first circuit board (133a) and a second circuit board (133b); forming a first electrically connecting pattern (134a) and a plurality of electrode pads (135) on the first circuit board (133a); forming a second electrically connecting pattern (134b) on the second circuit board (133b); mounting the first circuit board (133a) on a semiconductor chip (136) having a desired electrical function and having a plurality of electrode pads (137) thereon; mounting the chip (136) on the island (131); mounting the second circuit board (133b) on the inner leads (130); forming an electrically connecting means (138) between one of the inner leads (130a) and one of the electrode pads (137a) on the chip (136); forming an electrically connecting means (139) between another of the inner leads (130b) and the first electrically connecting pattern (134a); forming an electrically connecting means (170) between the first electrically connecting pattern (134a) and another of the electrode pads (137b) on the chip (136); forming an electrically connecting means (140) between another of the inner leads (130c) and the second electrically connecting pattern (134b); and forming an electrically connecting means (141) between the second electrically connecting pattern (134b) and a further one of the electrode pads (137c) on the chip (136).

Inventors: NAGANO JUNYA, NAGANO, JUNYA, Nagano, Junya, c/o Intellectual Property Division
Applicants: TOSHIBA KK, KABUSHIKI KAISHA TOSHIBA
Application year: 1991
Main classification: H01L23
IPC codes: H01L23, H01L25