JP2007240263A - Semiconductor integrated circuit and operation test method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately perform an operation test even when operation guarantee temperature is set to be high. <P>SOLUTION: A microcomputer 1 comprises a semiconductor substrate 2, input/output circuits 4 and 4A-E, a plurality of heat generating circuits 5A-5D, pads 3A-3C for inputting a control signal S1 for controlling the heat generating circuits, a temperature sensor 7, pads 3D and 3E for outputting a detected signal S3 by a temperature sensor to the outside, a decoder 6, and the like. The input/output circuits are connected with the pads arranged at predetermined intervals on a semiconductor substrate, and have an input/output buffer or the like. The heat generating circuits are arranged near the input/output circuits. The temperature sensor is a pn junction silicon diode. The decoder decodes the control signal generated by a control circuit disposed in a tool for evaluation based on the detected signal by the temperature sensor, and selects a heat generating circuit to be operated according to a decoding result every block. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a semiconductor integrated circuit provided with a heat generating circuit and an operation test method, for example, a microcomputer mounted in an engine room of an automobile or the like, and a technique effective when applied to an operation test thereof.

  For example, a microcomputer mounted in an engine room is subjected to an operation test for a certain period of time under operating conditions that are more stringent than the standard or the like in order to guarantee reliability. The conventional operation test has been carried out for several tens of hours at a high temperature of 125 ° C. in which the microcomputer held in the evaluation jig is housed in the furnace body and the furnace body is set to an operation guarantee temperature. The evaluation jig not only holds the microcomputer but also outputs predetermined input data to the microcomputer during the operation test, and whether or not the microcomputer outputs correct output data for this input data. It has a determination function, and includes, for example, each component of the measurement system having heat resistance up to 125 ° C. If correct output data is not output in this operation test, the microcomputer is regarded as a defective product as a device that potentially includes a defect.

  In recent years, the operation guarantee temperature for the microcomputer has been increased and changed from 125 ° C. to 160 ° C., for example. As a result, in the operation test, not only the heat resistance of the microcomputer but also the heat resistance of each component of the measurement system of the evaluation jig is required. However, each component of the measurement system may not have heat resistance up to 160 ° C. at present. For this reason, as an example of the operation test, the required operation guarantee temperature is 160 ° C. based on the evaluation result in an evaluable range, for example, 125 ° C., without actually raising the temperature of the microcomputer to 160 ° C. There is a method that predicts the result of and uses the predicted value as the evaluation result. In this case, there is a high possibility that the evaluation result and the result at the time of actual use do not coincide with each other, and a defect may occur at a high temperature.

  On the other hand, a semiconductor integrated circuit is known in which a microcomputer is provided with a heat generating circuit to raise the microcomputer itself to an operation guarantee temperature. Patent Document 1 discloses a semiconductor device as an object to be tested that includes a heat generating means. The heat generating means is configured such that a self-heating element such as a semiconductor element generates heat in accordance with a control signal pattern input from a tester. Patent Document 2 discloses a temperature detection circuit having a temperature sensor unit configured on a semiconductor substrate, and a heating element such as a heater formed using an embedded region is built in the vicinity of the temperature sensor unit. Has been.

JP 2001-091570 A Japanese Patent Laid-Open No. 10-325761

  The inventor has actually guaranteed the operation of the microcomputer without damaging each component even when the guaranteed operation temperature is, for example, 160 ° C. and exceeds the heat resistance of each component of the existing evaluation jig. We investigated the means to raise the temperature to perform the operation test with high accuracy. In the semiconductor device of Patent Document 1, it is described that the surface temperature of the semiconductor device can be controlled to be a preset temperature. However, the position and number of self-heating elements built in the semiconductor device on the semiconductor substrate are not disclosed. For this reason, the layout design may have to be significantly changed in order to arrange the self-heating elements on the semiconductor substrate. Furthermore, there is no guarantee that the surface temperature of the semiconductor device will be uniformly set temperature, only the part on the semiconductor substrate detected by the temperature sensor will be the set temperature, and it may be higher or lower than the set temperature in other places It is difficult to perform an operation test with high accuracy.

  On the other hand, in the temperature detection circuit of Patent Document 2, it is possible to easily test the temperature detection circuit because only the periphery of the temperature sensor unit can be heated by energizing and heating the heater during the test. However, in the operation test, not only the periphery of the temperature sensor unit but also the entire semiconductor substrate, such as the peripheral part of the semiconductor substrate, must be raised to the guaranteed operating temperature. In short, in the temperature detection circuit of Patent Document 2, since the heater is formed using the embedded region, it becomes difficult to make the entire semiconductor substrate have an operation guarantee temperature substantially uniformly.

  An object of the present invention is to provide a semiconductor integrated circuit and an operation test method capable of accurately performing an operation test even when the operation guarantee temperature is set high.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  The following is a brief description of an outline of typical inventions disclosed in the present application.

  [1] A semiconductor integrated circuit according to the present invention includes an input / output circuit (4, 4A to 4E), a plurality of heating circuits (5A to 5D), a first external terminal (3A to 3C), and a temperature sensor (7 ) And second external terminals (3D, 3E). A plurality of input / output circuits are arranged on the semiconductor substrate (2). The plurality of heat generating circuits are arranged in the vicinity of the input / output circuit or in the input / output circuit. A control signal (S1) for controlling the heat generating circuit is input to the first external terminal. The temperature sensor detects the temperature. The second external terminal outputs a detection signal (S3) from the temperature sensor to the outside.

  From the above, for example, an input / output circuit having an input / output buffer is connected to a plurality of external terminals arranged in a peripheral portion or a central portion of the semiconductor substrate. A plurality of heating circuits arranged in the vicinity of such an input / output circuit are distributed on the semiconductor substrate. Further, since a slight gap is formed between the adjacent external terminals, there is a gap enough to arrange the heat generating circuit between the adjacent input / output circuits. Also, depending on the input / output circuit, there may be a space in the circuit in which the heat generating circuit can be arranged. In that case, the circuit can be arranged in the input / output circuit. That is, the heat generating circuits can be distributed and arranged on the semiconductor substrate without significantly changing the layout design.

  Further, since each external terminal has a first external terminal and a second external terminal, it is output from the second external terminal by, for example, an operation test control circuit provided in the evaluation jig during the operation test. A control signal can be generated according to the detected signal from the temperature sensor, and this control signal can be input from the first external terminal to the heat generating circuit. In this way, in the operation test, even when the guaranteed operating temperature is, for example, 160 ° C. and exceeds the heat resistance of the evaluation jig, for example, 125 ° C., the heating circuit arranged dispersed on the semiconductor substrate is controlled. It can be controlled by a signal. Therefore, according to the semiconductor integrated circuit, the temperature of the evaluation jig is raised to 125 ° C. or more without raising the temperature of the semiconductor substrate substantially uniformly to the operation guarantee temperature, and the state is maintained for a predetermined time, for example, several tens of times. Can maintain time. In short, even when the guaranteed operating temperature is set high, the operation test can be accurately performed.

  Further, the temperature of the evaluation jig is made lower than the heat resistance. For example, both the semiconductor substrate and the evaluation jig are raised to a temperature of 125 ° C. using a furnace body, and then the semiconductor substrate is heated by a heating circuit. The temperature may be raised to the operation guarantee temperature. Further, the temperature of the semiconductor substrate may be raised from room temperature, for example, about 25 ° C. to an operation guarantee temperature by using only the heat generating circuit without using the furnace body.

  As a specific form of the present invention, the vicinity of the input / output circuit is between the input / output circuits. As described above, the heat generating circuit is arranged in a slight gap formed between adjacent input / output circuits, so that it is not necessary to greatly increase the area of the semiconductor substrate and the influence on the layout design can be reduced. .

  As a specific form of the present invention, when a plurality of the input / output circuits are arranged in the peripheral portion of the semiconductor substrate and the semiconductor substrate is rectangular, the input / output circuit is arranged in the vicinity of the opposing sides of the semiconductor substrate. The number of the heating circuits arranged is the same. From the above, the amount of heat generated by the heat generating circuit is uniformly transmitted from the peripheral portion of the semiconductor substrate toward, for example, the central portion. Thereby, the temperature of the semiconductor substrate can be uniformly raised to the operation guarantee temperature. Furthermore, since the temperature of the semiconductor substrate rises uniformly, the temperature detected by the temperature sensor matches the temperature of the entire semiconductor substrate, and the reliability of the operation test can be improved.

  As a specific form of the present invention, the temperature sensor is a diode. As described above, since it is easy to form a pn junction diode in the manufacturing process of the semiconductor integrated circuit, the manufacturing process is not significantly increased and the manufacturing cost can be reduced by using the diode as the temperature sensor.

  As a specific form of the present invention, a decoder (6) is provided that decodes the control signal and selects the heat generating circuit to be operated according to the decoding result in units of blocks. From the above, for example, when the heat generating circuit is disposed in the peripheral portion of the semiconductor substrate, the amount of heat generated from the heat generating circuit disposed in the peripheral portion of the semiconductor substrate by including adjacent heat generating circuits in different blocks, The number of blocks can be changed in stages. In short, the heat generating circuit can be controlled in units of blocks, and the temperature of the semiconductor substrate can be raised substantially uniformly with high accuracy.

  As a specific form of the present invention, the first external terminal is also used for the interface function of the first signal (S2) different from the input of the control signal. The second external terminal is also used for an interface function of a second signal (S4) different from the output of the detection signal. A first switching circuit (17), a second switching circuit (18), and a third external terminal (3F) are further included. The first switching circuit selectively connects the control signal transmission path (8A) and the first signal transmission path (19) to the first external terminal. The second switching circuit selectively connects the transmission path (9A) of the detection signal and the transmission path (20) of the second signal to the second external terminal. The third external terminal can switch and control the first switching circuit and the second switching circuit in common. From the above, the first external terminal is connected to the transmission path of the first signal during normal operation, and is connected to the transmission path of the control signal for controlling the heat generating circuit, for example, during the operation test. The second external terminal is connected to the transmission path of the second signal during normal operation, and is connected to the transmission path of the detection signal by the temperature sensor, for example, during an operation test. In short, since the first external terminal and the second external terminal have a plurality of functions, it is not necessary to provide a plurality of dedicated external terminals for performing an operation test, for example, by providing one third external terminal. Thereby, an operation test can be performed without significantly changing the number of lead pins.

  [2] In the semiconductor integrated circuit operation test method according to the present invention, a plurality of the heat generating circuits are divided into blocks, and a block to be operated is selected based on the detection signal output from the second external terminal. The number of the heat generating circuits that generate heat is variably controlled.

  From the above, if the number of heat generating circuits included in the block is the same, for example, if the heat generating circuit arranged in the peripheral part of the semiconductor substrate is included in the same block for every predetermined number, by selecting the block, The amount of heat generated at the periphery of the semiconductor substrate can be adjusted. Thereby, the temperature of the semiconductor substrate can be raised substantially uniformly to the operation guarantee temperature, and the temperature can be maintained for a predetermined time, so that the reliability of the operation test can be improved.

  The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

  That is, even when the guaranteed operating temperature is set high, the operation test can be accurately performed.

  FIG. 1 illustrates a schematic configuration of a microcomputer as an example of a semiconductor integrated circuit according to an embodiment of the present invention. For example, the microcomputer 1 is mounted in an engine room of an automobile or the like and may be used at a high temperature of about 160 ° C. for a long time. Therefore, the microcomputer 1 is subjected to an operation test so as not to cause a problem even under such severe operating conditions, and a defective product and a non-defective product are selected. In the figure, each circuit etc. mainly used at the time of this operation test is illustrated. The microcomputer 1 includes a semiconductor substrate 2, pads 3, 3A to 3E formed on the semiconductor substrate 2, input / output circuits (I / O) 4, 4A to 4E, heating circuits 5A to 5D, and a decoder 6 And a temperature sensor 7 and the like. In the figure, the pads 3, 3A to 3E and the input / output circuits 4, 4A to 4E are arranged on the semiconductor substrate 2, so that those having the same function are appropriately omitted and used for the operation test. For those having functions, etc., alphabets are added to the end of the reference numerals. Although the details of the heat generating circuits 5A to 5D will be described later, since the decoder 6 can be selected in units of blocks, an alphabet is added to the end of the code for each block.

  The semiconductor substrate 2 is formed in a square shape, and a plurality of pads 3, 3 </ b> A to 3 </ b> E are arranged at predetermined intervals around the semiconductor substrate 2. For example, the pad 3 is coupled to a lead of a lead frame (not shown) by wire bonding. The microcomputer 1 has a predetermined internal circuit (not shown) and the like. When the microcomputer 1 is incorporated into a predetermined system for performing normal operation after packaging, various signals are transmitted from the lead to the internal via the pad 3. Input to the circuit. On the other hand, the pads 3A to 3E mainly used for the operation test are not necessarily coupled to the leads. This is because when performing an operation test before packaging, the pads 3A to 3E may be connected to external terminals of an evaluation jig (not shown) and may not be used during normal operation after packaging. The evaluation jig not only simply holds the microcomputer 1 during the operation test, but also includes measurement system components having heat resistance up to 125 ° C., for example. The microcomputer 1 has a function of determining whether or not the microcomputer 1 has output correct output data for the input data.

  The input / output circuit 4 is connected to the pad 3 and includes, for example, an input / output buffer, and enables the exchange of signals between a predetermined system connected to the microcomputer 1 and the internal circuit. The input / output circuits 4A to 4C are connected to the decoder 6 via wirings 8A to 8C, respectively. The input / output circuits 4D and 4E are connected to the temperature sensor 7 via wirings 9A and 9B, respectively. The input / output circuits 4A to 4E are connected to the pads 3A to 3E and can be connected to an internal circuit (see FIG. 5).

  Since the input / output circuits 4 and 4A to 4E are respectively connected to the pads 3 and 3A to 3E arranged at a predetermined interval on the semiconductor substrate 2, only the heating circuits 5A to 5D are arranged therebetween. There are gaps. That is, the heat generating circuits 5A to 5D are respectively disposed between the adjacent input / output circuits 4 and 4A to 4E. As a result, the heat generating circuits 5A to 5D are arranged in a distributed manner around the periphery of the semiconductor substrate 2, and in addition, it is not necessary to change the layout design significantly in the design stage. Further, the heat generating circuits 5A to 5D are sufficiently small and do not increase the area of the semiconductor substrate 2.

  Wirings 10 </ b> A to 10 </ b> D are arranged along the periphery of the semiconductor substrate 2 so as not to overlap each other. These wirings 10A to 10D have a plurality of branches, and are connected to the heat generating circuits 5A to 5D via these branches, respectively. When the heat generating circuits 5A to 5D are arranged in the vicinity of one side of the semiconductor substrate 2, for example, the adjacent heat generating circuits 5A and 5B on the same side are connected to different wirings 10A and 10B, respectively. Similarly, adjacent heating circuits 5C and 5D on the same side are connected to different wirings 10C and 10D, respectively. In short, the plurality of heating circuits 5A to 5D can be distinguished as blocks for each of the wirings 10A to 10D. That is, the plurality of heat generating circuits 5A to 5D can be distinguished into four blocks, and adjacent ones on the same side are different blocks.

  The decoder 6 should be operated, for example, from the control circuit provided in the evaluation jig via the pads 3A to 3C and the input / output circuits 4A to 4C, that is, the control signal input via the wirings 8A to 8C. Decode the signal that points to the block. Based on the decoding result, the decoder 6 outputs a signal for selecting or deselecting an appropriate block to the wirings 11A to 11D. In short, the decoder 6 can select the heat generating circuits 5A to 5D to be operated in units of blocks. Here, the number of the heat generating circuits 5A to 5D included in the same block is the same. Therefore, by controlling the number of blocks selected by the decoder 6, the amount of heat generated by the heat generating circuits 5A to 5D is adjusted stepwise according to the number of selected blocks. The amount of heat generated by the heat generating circuits 5A to 5D is transmitted from the peripheral part to the central part of the semiconductor substrate 2, so that the temperature of the semiconductor substrate 2 can be increased uniformly to 160 ° C., which is an operation guarantee temperature. it can.

  FIG. 2 shows a schematic configuration of the heat generating circuit 5A as an example. Since the other heat generating circuits 5B to 5D have the same configuration, description thereof is omitted. The heat generating circuit 5 </ b> A includes a resistance element 12 formed of polycrystalline silicon (poly-Si) and a MOS switch 13. The resistance element 12 has one end connected to the power supply voltage Vcc and the other end connected to the MOS switch 13. One end of the MOS switch 13 is grounded as shown in the figure, and a signal from the decoder 6 is supplied to the gate 13a via wirings 11A and 10A. In this way, when the signal from the decoder 6 becomes high level, for example, the MOS switch 13 becomes conductive, current flows through the resistance element 12 to generate heat, and when the signal from the decoder 6 becomes low level, The MOS switch 13 is cut off, no current flows through the resistance element 12, and no heat is generated. In short, the heat generation circuit 5A is operable in accordance with a signal from the decoder 6. In addition, a total of 200 heat generating circuits 5A to 5D are arranged in the peripheral portion of the semiconductor substrate 2, and the heat generation of about 1 W as a whole is generated in order to raise the temperature of the semiconductor substrate 2 to 160 ° C., which is an operation guarantee temperature during the operation test. When required, the heat generation circuits 5A to 5D require a heat generation amount of 5 mW per piece. In such a case, the resistance element 12 and the MOS switch 13 can be arranged between the input / output circuits 4 adjacent to the heat generating circuit 5A, and the size and material so as to obtain the required heat generation amount. Etc. are appropriately selected.

  FIG. 3 schematically shows an example of the circuit configuration of the temperature sensor 7. The temperature sensor 7 is, for example, a pn junction silicon diode. The cathode side is connected to the input / output circuit 4D and the pad 3D via the wiring 9A, and the anode side is connected to the input / output circuit 4E and the pad 3E via the wiring 9B. It is connected. A constant current source 14 and a voltmeter 15 are connected between the pads 3D and 3E via wiring. The constant current source 14 and the voltmeter 15 are not arranged in the microcomputer 1 but, for example, in an evaluation jig. The constant current source 14 supplies a constant forward current to the diode. The voltmeter 15 measures the forward voltage of the diode. Thereby, the temperature characteristic of the diode, that is, the characteristic in which the voltage value changes according to the junction temperature can be measured.

  FIG. 4 shows an example of the temperature characteristics of the diode. In the figure, the horizontal axis represents temperature Ta = Tj (° C.), and the vertical axis represents voltage Vf (V). In order to measure the temperature characteristics of the diode, for example, all the heat generating circuits 5A to 5D are in an off state, and the forward voltage is measured in advance in an atmosphere at a room temperature of about 25 ° C. This measured value is defined as a reference point A (25, VfA) in the figure. If the forward voltage is measured at a temperature other than the reference point A, the temperature characteristic of the diode used as the temperature sensor 7, for example, −1.5 mV / ° C. can be measured. Thereby, the expression “Vf = VfA + (− 0.0015 × temperature change)” is obtained. The temperature can be calculated based on the voltage value measured by the voltmeter 15 during the operation test. In short, the temperature sensor 7 can detect the temperature of the semiconductor substrate 2 by using the temperature characteristic of the diode. Further, since a diode is used as the temperature sensor 7, it is easy to form a pn junction diode in the manufacturing process of the microcomputer 1. Thereby, it is not necessary to significantly change the manufacturing process of the microcomputer 1, and the manufacturing cost can be reduced.

  FIG. 5 shows an example of a circuit configuration including a pad that also functions as a plurality of functions. In the drawing, since the pads 3A to 3C and the pads 3D and 3E have substantially the same circuit configuration, the pad 3A and the pad 3D are representatively shown. Further, the pad 3F may be any of the pads 3 shown in FIG. The microcomputer 1 includes an internal circuit (INTCUIT) 16 as a circuit mainly used in normal operation. The pad 3A is connected to the switching circuit (SW) 17 via the input / output circuit 4A. The pad 3D is connected to the switching circuit (SW) 18 via the input / output circuit 4D. The pad 3F is connected to the switching circuits 17 and 18 via the input / output circuit 4F, respectively, and controls the switching circuits 17 and 18 in common.

  Switching circuit 17 includes a transmission path including a wiring 8A for transmitting control signal S1 to decoder 6 and a wiring 19 for transmitting a predetermined signal S2 to internal circuit 16 in accordance with a signal from pad 3F. The transmission path can be selectively switched, and one of these transmission paths is connected to the pad 3A. Thereby, the pad 3A is connected to the transmission path including the wiring 19 during normal operation, and is connected to the transmission path including the wiring 8A during the operation test. In short, the pad 3A is also used for the interface function of the predetermined signal S2, which is different from the input of the control signal S1.

  The switching circuit 18 also includes a transmission path including a wiring 9A for transmitting the detection signal S3 from the temperature sensor 7 according to a signal from the pad 3F, and a wiring for transmitting a predetermined signal S4 to the internal circuit 16. The transmission path including 20 can be selectively switched, and one of these transmission paths is connected to the pad 3D. Thereby, the pad 3D is connected to the transmission path including the wiring 20 during the normal operation, and is connected to the transmission path including the wiring 9A during the operation test. In short, the pad 3A is also used for the interface function of the predetermined signal S4 different from the input of the detection signal S3. Accordingly, since the microcomputer 1 includes the pads 3A to 3E that also have a plurality of functions, for example, by providing the pad 3F, it is not necessary to provide a plurality of dedicated pads that are used only during the operation test. In this way, the microcomputer 1 can perform an operation test without significantly changing the number of pads 3.

  Next, an operation test method in the microcomputer 1 will be described. First, the temperature characteristics of the diode used as the temperature sensor 7 are measured in advance. And the microcomputer 1 is hold | maintained with the jig | tool for evaluation, and is accommodated in the furnace body in the state. Since the evaluation jig has heat resistance up to 125 ° C., the furnace body raises the atmosphere inside the microcomputer 1 and the evaluation jig to 125 ° C. The furnace body maintains the temperature of the atmosphere at 125 ° C. Next, the microcomputer 1 controls the switching circuits 17 and 18 by the pad 3F to select, for example, the transmission path of the pad 3A and the decoder 6, and the transmission path of the pad 3D and the temperature sensor 7. The microcomputer 1 outputs the detection signal S3 from the temperature sensor 7 from the pad 3D to the operation test control circuit provided in the evaluation jig via the transmission path between the pad 3D and the temperature sensor 7. The operation test control circuit generates a control signal S1 indicating the number of heat generating circuits 5A to 5D to be operated based on the detection signal S3. The microcomputer 1 inputs the control signal S1 from the pad 3A to the decoder 6 through the transmission path between the pad 3A and the decoder 6.

  The decoder 6 decodes the control signal S1 and selects the heat generating circuits 5A to 5D to be operated according to the decoding result in units of blocks. For example, a total of 200 heat generating circuits 5A to 5D are arranged around the semiconductor substrate 2, and are divided into four blocks by wirings 10A to 10D, and the number contained in one block is 50. In the operation test, it is necessary to raise the temperature of the semiconductor substrate 2 to 160 ° C., which is an operation guarantee temperature. For this reason, the selection of the block units of the heat generating circuits 5A to 5D by the decoder 6 can be appropriately performed in consideration of the arrival time until reaching 160 ° C. For example, when it is desired to shorten the arrival time, all the four blocks may be selected and all the heat generating circuits 5A to 5D may be operated. Further, when it is not necessary to particularly shorten the arrival time, only one block, for example, the heat generation circuit 5A may be selected. Regardless of which block is selected, the amount of heat generated by the heat generating circuits 5A to 5D is transmitted from the peripheral portion of the semiconductor substrate 2 toward the central portion, so that the temperature of the semiconductor substrate 2 rises substantially uniformly.

  Further, since the temperature of the semiconductor substrate 2 is appropriately measured by the temperature sensor 7, the detection signal S3 from the temperature sensor 7 is input again to the control circuit of the evaluation jig. The control circuit again generates the control signal S1 for selecting the heat generating circuits 5A to 5D in units of blocks based on the difference between the guaranteed operating temperature and the current temperature. This control signal S1 is input to the decoder 6. For example, when all the blocks are selected, the temperature of the semiconductor substrate 2 exceeds 160 ° C., making it difficult to perform an accurate operation test. In order to avoid this, any block is not selected in the vicinity of 160 ° C., the total amount of heat generated by the heat generating circuits 5A to 5D is reduced, and the temperature of the semiconductor substrate 2 gradually reaches 160 ° C. Control. Further, when the temperature of the semiconductor substrate 2 is sufficiently lower than 160 ° C., the amount of heat generated by the heat generating circuits 5A to 5D is insufficient, so another block may be selected. As described above, by appropriately selecting the number of the heat generating circuits 5A to 5D to be operated, the temperature of the semiconductor substrate 2 can be raised substantially uniformly to 160 ° C., which is an operation guarantee temperature. Then, when the temperature of the semiconductor substrate 2 reaches the operation guarantee temperature, the microcomputer 1 operates an appropriate number of heat generating circuits 5A to 5D so as to maintain the state.

  When the temperature of the semiconductor substrate 2 reaches 160 ° C., the evaluation jig inputs operation test input data to, for example, the internal circuit 16 via the predetermined pad 3 and determines whether or not correct output data is output. To do. This determination is appropriately performed during, for example, several tens of hours when the temperature of the semiconductor substrate 2 is maintained at the operation guarantee temperature. If correct output data is always output in this determination, the microcomputer 1 is selected as a non-defective product. On the other hand, if incorrect output data is output, it is selected as a defective product as a device that potentially includes a defect. Therefore, in the operation test method of the microcomputer 1, the heat generation circuits 5 </ b> A to 5 </ b> D are selected in units of blocks by the decoder 6, thereby adjusting the amount of heat generated in the peripheral portion of the semiconductor substrate 2 and operating the temperature of the semiconductor substrate 2. The temperature can be raised substantially uniformly to the guaranteed temperature, and the temperature can be maintained for a predetermined time. Furthermore, during the operation test, the temperature of the evaluation jig does not exceed 125 ° C., and therefore is not damaged. In short, according to this operation test method, even when the guaranteed operation temperature is set high, the operation test can be performed with high accuracy and the reliability of the result of the operation test can be improved.

  As mentioned above, although the invention made by this inventor was concretely demonstrated based on embodiment, it cannot be overemphasized that this invention is not limited to it and can be variously changed in the range which does not deviate from the summary.

  For example, in the operation test, the furnace body is used to raise both the semiconductor substrate 2 and the evaluation jig to a temperature of 125 ° C., and then the temperature of the semiconductor substrate 2 is raised to a guaranteed operating temperature by the heating circuits 5A to 5D. However, it is not limited to this. For example, the temperature of the semiconductor substrate 2 may be raised from the normal temperature of about 25 ° C. to the operation guarantee temperature by using only the heating circuits 5A to 5D without using the furnace body. In this way, since the furnace body is not required during the operation test, the operation test can be performed more easily. In the operation test, the control signal S1 is generated using the operation test control circuit provided in the evaluation jig. However, the present invention is not limited to this. You may make it provide in. In this way, the configuration of the evaluation jig can be simplified.

  Furthermore, although the semiconductor substrate 2 is square, the present invention is not limited to this. If the heat generating circuits 5A to 5D can be appropriately arranged so that the temperature of the semiconductor substrate 2 can be raised substantially uniformly, a rectangle such as a rectangle can be used. It may also be an appropriate shape having a curve. The pads 3, 3 </ b> A to 3 </ b> E are not limited to the peripheral part of the semiconductor substrate 2, and a plurality of pads 3, 3 </ b> A to 3 </ b> D may be arranged, for example, in the central part. Further, depending on the input / output circuits 4 and 4A to 4E, there may be a space in which the heat generating circuits 5A to 5D can be arranged. Therefore, in this case, the heat generating circuits 5A to 5D can be arranged inside the input / output circuits 4 and 4A to 4E. Further, the microcomputer 1 described above has the heat generation circuits 5A to 5D and has a function of raising the temperature of the semiconductor substrate 2 substantially uniformly to the operation guarantee temperature, so that the microcomputer 1 is not limited to being mounted on a vehicle. The present invention can also be applied to an appropriate control system that requires heat resistance and its operation test.

1 is an explanatory diagram illustrating a schematic configuration of a microcomputer that is an example of a semiconductor integrated circuit according to an embodiment of the invention; FIG. It is a circuit diagram which illustrates schematic structure of a heat generating circuit. It is a circuit diagram which illustrates schematic structure of a temperature sensor. It is a characteristic view which illustrates the temperature characteristic of a diode. It is explanatory drawing which illustrates the pad which combines a some function.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Microcomputer 2 Semiconductor substrate 3, 3A-3E Pad 4, 4A-4E Input / output circuit (I / O)
5A to 5D Heat generation circuit 6 Decoder (DEC)
7 Temperature sensor (TEMPSES)
12 Resistance element 13 MOS switch 14 Constant current source 15 Voltmeter 16 Internal circuit (INTCUIT)
17, 18 switching circuit S1 control signal S3 detection signal

Claims (7)

A plurality of input / output circuits arranged on a semiconductor substrate;
A plurality of heat generating circuits arranged in the vicinity of the input / output circuit or in the input / output circuit;
A first external terminal for inputting a control signal for controlling the heating circuit;
A temperature sensor for detecting the temperature;
And a second external terminal for outputting a detection signal from the temperature sensor to the outside.   The semiconductor integrated circuit according to claim 1, wherein the vicinity of the input / output circuit is between the input / output circuits.   When a plurality of the input / output circuits are arranged in the periphery of the semiconductor substrate and the semiconductor substrate is rectangular, the number of the heating circuits arranged in the vicinity of the opposing sides of the semiconductor substrate is the same. The semiconductor integrated circuit according to claim 1.   The semiconductor integrated circuit according to claim 1, wherein the temperature sensor is a diode.   2. The semiconductor integrated circuit according to claim 1, further comprising a decoder that decodes the control signal and selects the heat generating circuit to be operated according to a decoding result in units of blocks. The first external terminal is also used for an interface function of a first signal different from the input of the control signal,
The second external terminal is also used for an interface function of a second signal different from the output of the detection signal,
A first switching circuit for selectively connecting the transmission path of the control signal and the transmission path of the first signal to the first external terminal;
A second switching circuit that selectively connects the transmission path of the detection signal and the transmission path of the second signal to the second external terminal;
2. The semiconductor integrated circuit according to claim 1, further comprising a third external terminal capable of switching and controlling the first switching circuit and the second switching circuit in common. An operation test method for a semiconductor integrated circuit according to claim 5,
A semiconductor integrated circuit that divides a plurality of heat generating circuits into blocks, selects a block to be operated based on the detection signal output from the second external terminal, and variably controls the number of heat generating circuits that generate heat Operation test method.

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