Semi-conductor device having circuits on both sides of insulation layer and ultrasonic signal path between the circuits

Abstract: A semiconductor device having a semiconductor substrate (11) or an insulation layer (58), an integrated circuit on each side of the semiconductor substrate (11) or an insulation layer (58), and a path for an ultrasound signal connecting both integrated circuits. The path is realized through the semiconductor substrate (11) or insulation layer (58) by providing an ultrasonic transducer on each side of the semiconductor substrate (11) or an insulation layer (58). A plurality of paths may be provided in the same semiconductor substrate (11) or an insulation layer (58) without crosstalk by transmitting ultrasound signals having different frequencies through the respective paths. The paths may be one-way or two-way. The ultrasonic transducers (17a to 17d) each contain a piezoelectric material, and the thickness of the piezoelectric material (14a to 14d) in the ultrasonic transducer at least on a receiver side in each path is such that the resonant frequency of the ultrasonic transducer corresponds to the frequency of the ultrasound signal transmitted through the path. A plurality of paths transmitting an ultrasound signal having the same frequency may be provided between at least one point on one side and more than one point on the other side, through the semiconductor substrate (11) or insulation layer (58), when each of the paths is used in a time-sharing manner.

Description: (1) Field of the Invention The present invention relates to a semiconductor device having a plurality of layers each containing an integrated circuit and being electrically isolated from the others, and at least one ultrasound signal path provided between two of the integrated circuits. The layers containing the integrated circuits may be provided on one side of a semiconductor substrate, or on both sides of the semiconductor substrate. By forming a plurality of layers each containing an integrated circuit in a semiconductor device, many circuit elements can be accumulated within the semiconductor device. (2) Description of the Related Art Conventionally, a technique for forming integrated circuits on both sides of a semiconductor substrate is known, but there is no prior art which realizes a path for transmitting a signal between the integrated circuits on both sides of the semiconductor substrate. Japanese Unexamined Patent Publication No. 59-50583 by the present inventor discloses a technique for providing a single ultrasound signal path between two layers each containing integrated circuits, and electrically isolated from one another. Figure 1 shows a conventional construction providing a signal path between two integrated circuits which are respectively provided on different layers of a semiconductor substrate. In Fig. 1, reference numeral 41 denotes a semiconductor substrate, 42 and 48 each denote an interlayer insulation layer, 43a and 43b each denote a first wire layer, 44a and 44b each denote a layer of a piezoelectric material, 45a and 45b each denote a second insulation layer, 46a and 46b each denote a second wire layer, and 49 denotes a surface protection layer. A first ultrasonic transducer is constituted on the insulation layer 42 by the first wire layer 43a, the layer of piezoelectric material 44a, and the second wire layer 47a, and a second ultrasonic transducer is constituted on the insulation layer 48 by the first wire layer 43b, the layer of piezoelectric material 44b, and the second wire layer 47b. When an ultrasound signal is generated in one ultrasonic transducer, the ultrasound signal is propagated through the interlayer insulation layer 48 to the other ultrasonic transducer, and the ultrasound signal is converted to an electric signal in the ultrasonic transducer receiving the ultrasound signal. The ultrasound signal is generated in either of the ultrasonic transducers by applying a varying electric signal to the layer of piezoelectric material in the ultrasonic transducer, through the first and second wire layers 43a and 46a (or 43b and 46b). Nevertheless, when more than one signal path becomes necessary between the different layers, which are separated by an insulation layer, crosstalk may occur between different signal paths in the insulation layer. An object of the present invention is to provide a semiconductor device having a plurality of layers each containing an integrated circuit, which are electrically isolated from one another, and more than one signal path is provided between two of the integrated circuits to thereby prevent crosstalk between different signal paths. According to claim 1 of the present invention there is provided a semiconductor device comprising: first and second integrated circuits respectively provided on first and second sides of an insulation layer, this insulation layer being provided between the first and second integrated circuits for insulating them from one another; characterised in that the device further comprises a plurality of groups of ultrasonic transducers, each group including a least one first-side ultrasonic transducer and at least one second-side ultrasonic transducer each first-side ultrasonic transducer in each group being provided on one side of the insulation layer and connected to the integrated circuit on that side, for transforming an electric signal from the integrated circuit to an ultrasound signal and outputting the ultrasound signal through the insulation layer, and each second-side ultrasound transducer of each group being provided on the other side of the insulation layer and connected to the other integrated circuit, for receiving the ultrasound signal output through the insulation layer and transforming it to an electric signal to be supplied to the integrated circuit on the same side upon receipt of an ultrasound signal from the first-side ultrasonic transducer in the same group; the second-side ultrasonic transducers in all groups being each constituted by a respective layer of piezoelectric material on the insulation layer, the thicknesses of the layers being the same within each group and being different as between the groups. In the above construction of the present invention, the above insulation layer may be a semiconductor substrate, and the above first and second integrated circuits may be respectively provided on first and second sides of the semiconductor substrate. Further, the above first integrated circuit may comprise a high frequency modulator for each first-side ultrasonic transducer in each group for modulating an electric signal, to be supplied from the first integrated circuit to the first-side ultrasonic transducer, with a high-frequency carrier wave having a frequency which corresponds to a resonant frequency of each second ultrasonic transducer in the same group, to supply the modulated signal to the first ultrasonic transducer; and the second integrated circuit may comprise a high-frequency demodulator for each second-side ultrasonic transducer in each group, for receiving the electric signal generated by the transforming operation in the second-side ultrasonic transducer, and demodulating the electric signal which is modulated with the high-frequency carrier wave having the frequency which corresponds to the resonant frequency of each second ultrasonic transducer in the same group. Each second-side ultrasonic transducer in each group, on the second side of the insulation layer and connected with the second integrated circuit, is preferably also adapted for transforming an electric signal to an ultrasound signal and outputting the ultrasound signal through the insulation layer when the electric signal is applied thereto from the second integrated circuit, in addition to receiving the ultrasound signal from the first-side ultrasonic transducer in the same group. In this case the thickness of the piezoelectric materials of the first-and second-side ultrasonic transducers in each group are the same, and the piezoelectric layers of the first- and second-side ultrasonic transducers have different thicknesses for different groups. For a better understanding of the invention various embodiments will now be discussed with reference to the accompanying drawings. In the drawings: Figure 1 shows a conventional construction providing a signal path between two integrated circuits provided respectively on different layers of a semiconductor substrate; Figure 2 shows a construction providing a plurality of signal paths between two integrated circuits provided respectively on different layers of a semiconductor device; Figure 3 shows a construction providing a signal path between two integrated circuits provided respectively on two sides of a semiconductor substrate; Figure 4 shows a construction providing a plurality of signal paths between two integrated circuits provided respectively on different layers of a semiconductor device; Figure 5 shows a provision of FET's on ways between ultrasonic transducers and corresponding integrated circuits; and Figures 6A to 6D are diagrams respectively showing various ways of providing signal paths between two layers each containing an integrated circuit which are electrically isolated from one another. Fig. 2 Figure 2 shows a construction providing a plurality of signal paths between two integrated circuits provided in different layers of a semiconductor device on one side of a semiconductor substrate. In Fig. 2, reference numeral 51 denotes a semiconductor substrate; 52 and 58 each denote an interlayer insulation layer formed of, for example, polyimide or SiO 2 ; 53a, 53b, 53c, and 53d each denote a first wire layer formed of, for example, aluminum; 54a, 54b, 54c, and 54d each denote a layer of a piezoelectric material, for example, ZnO or LiNbO 3 ; 55a, 55b, 55c, and 55d each denote a second insulation layer formed of, for example, PSG (Phospho-Silicate Glass); 56a, 56b, 56c, and 56d each denote a second wire layer formed of, for example, aluminum; and 57a, 57b, 57c, and 57d each denote an ultrasonic transducer. The ultrasonic transducer 57a is constituted on the insulation layer 52 by the first wire layer 53a, the layer of piezoelectric material 54a, and the second wire layer 56a; the ultrasonic transducer 57b is constituted on the insulation layer 58 by the first wire layer 53b, the layer of piezoelectric material 54b, and the second wire layer 56b; the ultrasonic transducer 57c is constituted on the insulation layer 58 by the first wire layer 53c, the layer of piezoelectric material 54c, and the second wire layer 56c; and the ultrasonic transducer 57d is constituted on the insulation layer 52 by the first wire layer 53d, the layer of piezoelectric material 54d, and the second wire layer 56d. The thickness of the layer of piezoelectric material 54a in the ultrasonic transducer 57a and the thickness of the layer of piezoelectric material 54b in the ultrasonic transducer 57b are the same, and the thickness of the layer of piezoelectric material 54c in the ultrasonic transducer 57c and the thickness of the layer of piezoelectric material 54d in the ultrasonic transducer 57d are the same. The thickness of the layers of piezoelectric material 54a or 54b is different from the thickness of the layers of piezoelectric material 54c or 54d. Each of the ultrasonic transducers 57a, 57b, 57c, and 57d generates an ultrasound signal so that the generated ultrasound signal is propagated in the insulation layer 58 when a high frequency electric signal is applied thereto through the first and second wire layers thereof. The frequency of the generated ultrasound signal is equal to the frequency of the high frequency electric signal. When the frequency of the high frequency electric signal corresponds to a resonant frequency of one of the ultrasonic transducers on the other side of the insulation layer 58, the layer of piezoelectric material in the ultrasonic transducer on the other side vibrates in resonation with the ultrasound signal propagated through the insulation layer 58, and a high frequency electric signal having the above frequency is generated in the resonating ultrasonic transducer to thereby output the high frequency electric signal through the first and second wire layers of the ultrasonic transducer. Since the thickness of the layer of piezoelectric material in each ultrasonic transducer on each side of the insulation layer 58 is different, the resonant frequencies of the ultrasonic transducers on each side are different, and therefore, only one ultrasonic transducer on each side can be resonated with an ultrasound signal propagated from the other side of the insulation layer 58. Although not shown, the first and second wire layers of each ultrasonic transducer are connected with an integrated circuit formed on the same side of the semiconductor substrate 11 as the ultrasonic transducer. When the transmission of the ultrasound signal is carried out in two ways, between the ultrasonic transducers formed on different sides and containing layers of piezoelectric material having the same thickness, as shown in Fig. 2, the integrated circuit comprises a modulator and demodulator, and the above first and second wire layers of each ultrasonic transducer are connected to an output port of the modulator and an input port of the demodulator so that an electric signal transmitted to an integrated circuit formed on the other side of the semiconductor substrate 51 is modulated with a high frequency carrier wave, and a high frequency electric signal generated in the ultrasonic transducer is demodulated and the demodulated signal is supplied to another portion of the integrated circuit, where the characteristic frequencies of the modulator and the demodulator are equal to the resonant frequency of the corresponding ultrasonic transducer. When the transmission of the ultrasound signal is carried out in only one way between the ultrasonic transducers being formed on different sides, an integrated circuit which generates an electric signal to be transmitted to an integrated circuit on the other side comprises a modulator, and an integrated circuit which is to receive an electric signal transmitted from an integrated circuit on the other side comprises a demodulator, where the characteristic frequency of the demodulator is equal to the resonant frequency of the ultrasonic transducer to which the demodulator is connected. Fig. 3 Figure 3 shows a construction providing a signal path between two integrated circuits provided respectively on two sides of a semiconductor substrate. In Fig. 3, reference numeral 31 denotes a semiconductor substrate formed of, for example, silicon, 32a and 32b each denote a first insulation layer formed of, for example, SiO 2 ; 33a and 33b each denote a wire layer formed of, for example, aluminum; 34a and 34b each denotes a second insulation layer formed of, for example, PSG; 35 denotes a bonding pad; 36 denotes a bump formed of, for example, aluminum or gold; 37 denotes a circuit board formed of, for example, ceramics; 38 denotes a printed circuit formed of, for example, copper; and 39 denotes a bonding wire formed of, for example, aluminum. The first insulation layers 32a and 32b are formed respectively on both sides of the semiconductor substrate 31; the wire layers 33a and 33b are formed respectively on both first insulation layers 32a and 32b; and the second insulation layers 34a and 34b are formed respectively on both the wire layers 33a and 33b. On the upper side of the semiconductor substrate 31, an opening is provided in the second insulation layer 34a to allow a bonding pad 35 to be formed on a surface of the wire layer 33a, and one end of the bonding wire 39 is bonded to the bonding pad 35. The printed circuit 38 is formed on the circuit board 37, and the other end of the bonding wire 39 is bonded to a certain point on the printed circuit 38. The bury 36 is formed on the wire layer 33b to bond the wire layer 33b to a certain point on the printed circuit 38 in a manner similar to a flip-chip bonding. Accordingly, when a signal path is formed between the point at which the above other end of the bonding wire 39 is bonded to the printed circuit 38, and the point at which the bump 36 is bonded to the printed circuit 38, a path for transmitting a signal is formed between an integrated circuit which is formed on the upper side of the semiconductor substrate 31 and an integrated circuit which is formed on the lower side of the semiconductor substrate 31, through the printed circuit 38 on the circuit board 37. To form the integrated circuits on both sides of the semiconductor substrate, first a wafer with a mask is provided on each side thereof is exposed in an exposing apparatus, to thus simultaneously expose both sides of the wafer. Then, the conductor layers and the insulation layers are formed, and etching is carried out by positioning the wafer upright in a semiconductor device manufacturing device such as a CVD apparatus. In the above construction of Fig. 3, however, a relatively large area is required for providing the bonding pad and the bump (for example, 100µm × 100µm), and therefore, the degree of accumulation in the semiconductor device is reduced because when many signal paths are provided in a semiconductor device, the areas occupied by the bonding pads and the bumps become very large compared with the areas of the integrated circuits. A technique similar to that of the above first embodiment can be applied to the semiconductor device having integrated circuits on both sides thereof, to provide more than one signal path between the integrated circuits provided on both sides, as explained below. Figs. 4 and 5 Figure 4 shows a construction providing a plurality of signal paths between two integrated circuits provided respectively on two sides of the semiconductor substrate. In Fig. 4, reference numeral 11 denotes a semiconductor substrate; 12a and 12b each denote a first insulation layer formed of, for example, SiO 2 ; 13a, 13b, 13c, and 13d each denote a first wire layer formed of, for example, aluminum; 14a, 14b, 14c, and 14d each denote a layer of a piezoelectric material, for example, ZnO; 15a, 15b, 15c, and 15d each denote a second wire layer formed of, for example, aluminum; 16a, 16b, 16c, and 16d each denote a second insulation layer formed of, for example, PSG; and 17a, 17b, 17c, and 17d each denote an ultrasonic transducer. The ultrasonic transducer 17a is constituted on the insulation layer 12a by the first wire layer 13a, the layer of piezoelectric material 14a, and the second wire layer 15a; the ultrasonic transducer 17b is constituted on the insulation layer 12b by the first wire layer 13b, the layer of piezoelectric material 14b, and the second wire layer 15b; the ultrasonic transducer 17c is constituted on the insulation layer 12a by the first wire layer 13c, the layer of piezoelectric material 14c, and the second wire layer 15c; and the ultrasonic transducer 14d is constituted on the insulation layer 12b by the first wire layer 13d, the layer of piezoelectric material 14d, and the second wire layer 15d. The thickness of the layer of piezoelectric material 14a in the ultrasonic transducer 17a and the thickness of the layer of piezoelectric material 14b in the ultrasonic transducer 17b are the same, and the thickness of the layer of piezoelectric material 14c in the ultrasonic transducer 17c and the thickness of the layer of piezoelectric material 14d in the ultrasonic transducer 17d are the same. The thickness of the layers of piezoelectric material 14a or 14b is different from the thickness of the layers of piezoelectric material 14c or 14d. Each of the ultrasonic transducers 17a, 17b, 17c, and 17d generates an ultrasound signal so that the generated ultrasound signal is propagated in the semiconductor substrate 11 when a high frequency electric signal is applied thereto through the first and second wire layers thereof. The frequency of the generated ultrasound signal is equal to the frequency of the high frequency electric signal. When the frequency of the high frequency electric signal corresponds to a resonant frequency of one of the ultrasonic transducers on the other side of the semiconductor substrate 11, the layer of piezoelectric material in the ultrasonic transducer on the other side vibrates in resonance with the ultrasound signal propagated through the semiconductor substrate 11, and a high frequency electric signal having the above frequency is generated in the resonating ultrasonic transducer and is output through the first and second wire layers of the ultrasonic transducer. Since the thickness of the layer of piezoelectric material in each ultrasonic transducer on each side of the semiconductor substrate 11 is different, the resonant frequencies of the ultrasonic transducers on each side are different, and therefore, only one ultrasonic transducer on each side can resonate with an ultrasound signal propagated from the other side of the semiconductor substrate 11. Although not shown, the first and second wire layers of each ultrasonic transducer are connected with an integrated circuit formed on the same side of the semiconductor substrate 11 as the ultrasonic transducer. Before an electric signal from an integrated circuit is applied to the ultrasonic transducer, the signal may be amplified through a FET 23a formed on the same side of the semiconductor substrate as the integrated circuit and the ultrasonic transducer 28a as shown in Fig. 5, and a high frequency electric signal generated in the ultrasonic transducer 28b may be amplified through an FET 23b formed on the same side of the semiconductor substrate as the ultrasonic transducer 28b before the signal is applied to an integrated circuit on the same side as the ultrasonic transducer 28b. Although only one FET is connected with each ultrasonic transducer in Fig. 5, two FET's may be connected to the ultrasonic transducer in parallel, one on the way to the ultrasonic transducer and the other on the way from the ultrasonic transducer, when the ultrasonic transducer is used for either generating and transmitting an ultrasound signal, and receiving the ultrasound signal and converting the ultrasound signal to an electric signal, i.e., when the signal path between the ultrasonic transducers is two-way. Although not shown, a modulator and/or demodulator is provided for each ultrasonic transducer in a manner similar to the construction of Fig. 2. A layer of piezoelectric material is formed, for example, of ZnO, using the RF magnetron sputtering method under the following conditions: RF power: 150W Atmosphere: a mixed gas of Ar and 02 where Ar : O 2 = 1 : 1 Pressure: 6mTorr Temperature of Substrate: 220°C The thickness of the layers of piezoelectric material 14a or 14b is, for example, 3,000Å, and the thickness of the layers of piezoelectric material 14c or 14d is, for example, 5,000Å. The resonant frequency of the ultrasonic transducer is theoretically obtained from the thickness t of the layer of piezoelectric material and the velocity v of the longitudinal wave in the piezoelectric material, as v/2t. Since the velocity v of the longitudinal wave in ZnO is 6,200 m/sec, the resonant frequency of the ultrasonic transducer containing the layer of ZnO having the thickness of 3,000Å is 15.5 GHz, and the resonant frequency of the ultrasonic transducer containing the layer of ZnO having the thickness of 5,000Å is 12.4 GHz. In practice, since the layer of ZnO is sandwiched between the first and second wire layers, and is buried in the insulation layers as shown in Fig. 4, the measured values of the resonant frequencies are about 16GHz for the thickness of 3,000Å and about 13GHz for the thickness of 5,000Å, respectively. According to the above construction of Fig. 4, crosstalk between different signal paths in the same semiconductor substrate can be prevented because ultrasound signals having different frequencies respectively are propagated through the signal paths, and the ultrasonic transducers in the receiver side do not resonate upon reception of an ultrasound signal having a frequency different from the resonant frequency of the ultrasonic transducer. Further, the area required for providing the ultrasonic transducer is reduced in the construction of Fig. 4, compared with the construction of Fig. 3, for example, to 50µm × 50µm. Namely, the degree of accumulation in the semiconductor device is increased. These features are particularly advantageous when many signal paths are provided in a semiconductor device. Figs. 6A to 6D Figures 6A to 6D are diagrams respectively showing various ways of providing signal paths between two layers each containing an integrated circuit and electrically isolated from one another. In Figs. 6A to 6D, reference numerals 61 and 62 each denote a layer containing an integrated circuit and a plurality of ultrasonic transducers connected to the integrated circuit, and 63 denotes a layer which electrically isolates the integrated circuits from one another. In the construction of Fig. 6A, reference numerals 64 to 69 each denote an ultrasonic transducer, and a signal path is provided between a pair of ultrasonic transducers located on two sides of the insulation layer 63. Each signal path may be either one-way or two-way. In the construction of Fig. 6B, reference numerals 70, 71 1 , 71 2 , ... 71 n , 72, 73 1 , 73 2 , ... 73 n each denote an ultrasonic transducer. The ultrasonic transducers 70, 71 1 , 71 2 , ... 71 n belong to a group, and the ultrasonic transducers 72, 73 1 , 73 2 , ... 73 n belong to another group. The ultrasonic transducers 71 1 , 71 2 , ... 71 n each receive an ultrasound signal transmitted from the corresponding ultrasonic transducer 70, and the ultrasonic transducers 73 1 , 73 2 , ... 73 n each receive an ultrasound signal which is transmitted from the corresponding ultrasonic transducer 72. The ultrasonic transducers 71 1 , 71 2 , ... 71 n each contain a layer of piezoelectric material of the same thickness, and the ultrasonic transducers 73 1 , 73 2 , ... 73 n each contain a layer of piezoelectric material of the same thickness. The thickness of the layer of piezoelectric material in each ultrasonic transducer 71 1 , 71 2 , ... 71 n and the thickness of the layer of piezoelectric material in each ultrasonic transducer 73 1 , 73 2 , ... 73 n are different. Namely, the frequencies of the ultrasound signals transmitted between the ultrasonic transducers in the different groups are different. In the construction of Fig. 6C, reference numerals 74, 75 1 , 75 2 , ... 75 n , 76, 77 1 , 77 2 , ... 77 n each denote an ultrasonic transducer. The ultrasonic transducers 74, 75 1 , 75 2 , ... 75 n belong to one group, and the ultrasonic transducers 76, 77 1 , 77 2 , ... 77 n belong to another group. The ultrasonic transducer 74 receives an ultrasound signal transmitted from one of the corresponding ultrasonic transducers 75 1 , 75 2 , ... 75 n , in a time sharing manner, and the ultrasonic transducer 76 receives an ultrasound signal transmitted from one of the corresponding ultrasonic transducers 77 1 , 77 2 , ... 77 n , in a time sharing manner. Namely, the ultrasonic transducers 75 1 , 75 2 , ... 75 n each output an ultrasound signal to the ultrasonic transducer 74 at a different time t 1 , t 2 , ... t n , and the ultrasonic transducers 77 1 , 77 2 , ... 77 n each output an ultrasound signal to the ultrasonic transducer 76 at a different time t 1 ′, t 2 ′, ... t n ′. The ultrasonic transducers 75 1 , 75 2 , ... 75 n each output an ultrasound signal having a frequency equal to the frequency of a resonant frequency of the ultrasonic transducer 74, and the ultrasonic transducers 77 1 , 77 2 , ... 77 n each output an ultrasound signal having a frequency equal to the frequency of a resonant frequency of the ultrasonic transducer 76. The thickness of the layer of piezoelectric material in each ultrasonic transducer 74 and the thickness of the layer of piezoelectric material in each ultrasonic transducer 76 are different. Namely, the frequencies of the ultrasound signals which are transmitted between the ultrasonic transducers in the different groups are different. In the constructions of Figs. 6B and 6C, the transmission of the ultrasound signals may be carried out in two-way on each signal path. In this case, the thickness of the layer of piezoelectric material in all the ultrasonic transducers on both sides in each group is the same. In the construction of Fig. 6D, reference numerals 78 1 , 78 2 , ... 78 n , and 79 1 , 79 2 , ... 79 m , 80 1 , 80 2 , ... 80 n , and 81 1 , 81 2 , ... 81 m each denote an ultrasonic transducer. The ultrasonic transducers 78 1 , 78 2 , ... 78 n , and 79 1 , 79 2 , ... 79 m belong to one group, and the ultrasonic transducers 80 1 , 80 2 ... 80 n , and 81 1 , 81 2 , ... 81 n belong to another group. A transmission of ultrasound signals can be carried out in the same way between the ultrasonic transducers on two sides of the insulation layer 63 in each group, as explained above with reference to Figs. 6A to 6C. Namely, each ultrasonic transducer on one side in each group can transmit and/or receive an ultrasound signal, as any one of the ultrasonic transducers in the constructions of Figs. 6A to 6C.

Claims: A semiconductor device comprising: first and second integrated circuits respectively provided on first and second sides of an insulation layer (58; 31; 11; 21; 63), this insulation layer (63) being provided between the first and second integrated circuits for insulating them from one another; the device further comprises: a plurality of groups of ultrasonic transducers, each group including a least one first-side ultrasonic transducer (17a; 28a; 64; 70; 74; 78 i ) and at least one second-side ultrasonic transducer (17b; 28b; 65; 71 i ; 75 i ; 79 i ) each first-side ultrasonic transducer (78 i ) in each group being provided on one side of the insulation layer (63) and connected to the integrated circuit on that side, for transforming an electric signal from the integrated circuit to an ultrasound signal and outputting the ultrasound signal through the insulation layer (63), and each second-side ultrasound transducer of each group being provided on the other side of the insulation layer (63) and connected to the other integrated circuit, for receiving the ultrasound signal output through the insulation layer (63) and transforming it to an electric signal to be supplied to the integrated circuit on the same side upon receipt of an ultrasound signal from the first-side ultrasonic transducer (78 i ) in the same group; characterised in that the second-side ultrasonic transducers (79 i ) in all groups being each constituted by a respective layer of piezoelectric material on the insulation layer (63), the thicknesses of the layers being the same within each group and being different as between the groups (79 i , 81 i ). A semiconductor device according to claim 1, in which all the first-side ultrasonic transducers are constituted by a layer of piezoelectric material and the thicknesses of the piezoelectric material layers of the first-side ultrasonic transducers in each group are the same within each group and are different as between the groups. A semiconductor device according to claim 1 or 2, wherein the first integrated circuit includes a high-frequency modulator for each first-side ultrasonic transducer (78 i ) in each group, for modulating an electric signal to be supplied from the first integrated circuit to the first-side ultrasonic transducer (78 i ) with a high-frequency carrier wave having a frequency which corresponds to a resonant frequency of each second-side ultrasonic transducer in the same group, and supplying the modulated signal to the first-side ultrasonic transducer; and the second integrated circuit includes a high-frequency demodulator for each second-side ultrasonic transducer (79 i ) in each group, for receiving the electric signal generated by the transforming operation in the second-side ultrasonic transducer (79 i ), and demodulating this electric signal. A semiconductor device as claimed in any preceding claim, in which each first-side ultrasonic transducer (78 i ) in each group, and each second-side ultrasonic transducer (79 i ) in each group, is provided on the respective side of the insulation layer (63) and connected to the respective integrated circuit, both for transforming an electric signal to an ultrasound signal and outputting the ultrasound signal through the insulation layer (63) when the electric signal is applied thereto from the integrated circuit, and for transforming an ultrasound signal to an electric signal and supplying the electric signal to the respective integrated circuit when an ultrasound signal is applied thereto from an ultrasonic transducer (79 i ) on the other side in the same group through the insulation layer (63). A semiconductor device according to any preceding claim, in which the second integrated circuit includes a high-frequency modulator for each second-side ultrasonic transducer (79 i ) in each group, for modulating an electric signal to be supplied from the second integrated circuit to the second-side ultrasonic transducer (79 i ) with a high-frequency carrier wave having a frequency which corresponds to a resonant frequency of each first-side ultrasonic transducer in the same group and supplying the modulated signal to the second-side ultrasonic transducer, and the first integrated circuit includes a high-frequency demodulator for each first-side ultrasonic transducer (78 i ) for receiving the electric signal generated by the transforming operation in the first-side ultrasonic transducer (78 i ), and demodulating this electric signal. A semiconductor device according to any preceding claim, wherein each ultrasonic transducer comprises: a first conductor layer (43) formed on the insulation layer (48), and connected to a terminal of the integrated circuit on the same side as the ultrasonic transducer, a layer of piezoelectric material (44) on the first conductor layer, and a second conductor layer (46) formed on the piezoelectric layer, and connected to another terminal of the integrated circuit on the same side as the ultrasonic transducer. A semiconductor according to any preceding claim, in which the first and second integrated circuits are respectively provided on the first and second sides of a semiconductor substrate (11, 21, 31, 63), this substrate constituting the said insulation layer. A semiconductor device according to claim 7, wherein an insulation layer (12, 22, 32) is formed on each side of the semiconductor substrate, and each ultrasonic transducer is formed on the corresponding insulation layer.

Inventors: SASAKI NOBUO, SASAKI, NOBUO
Applicants: FUJITSU LTD, FUJITSU LIMITED
Application year: 1991
Main classification: H01L21
IPC codes: H01L27, H01L23, H01L41