JP2004179505A - Semiconductor integrated circuit and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce manufacturing costs by reducing the number of times of measuring oscillation frequency in the case of trimming resistance values or capacity values in a semiconductor integrated circuit in which a CR oscillation circuit is built. <P>SOLUTION: The semiconductor integrated circuit is provided with a trimming circuit 16 for selecting at least one resistor on the basis of trimming data, a CR oscillation circuit 11 capable of performing oscillation using a resistor selected by the trimming circuit 16, a counter 13 for counting output signals from the CR oscillation circuit, a judgment circuit 14 for judging whether a count value is in a prescribed range or not, a memory 18 for storing trimming data corresponding to a count value included in the prescribed range, and a trimming control circuit 15 for generating trimming data so as to select a plurality of resistors in a prescribed order in a test mode and controlling the trimming circuit 16 by using the trimming data stored in the memory 18 in a normal mode. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention generally relates to a semiconductor integrated circuit, and more particularly, to a semiconductor integrated circuit having a built-in CR oscillation circuit. Further, the present invention relates to a method for manufacturing such a semiconductor integrated circuit.
[0002]
[Prior art]
In a semiconductor integrated circuit having a built-in CR oscillation circuit, capacitance values and resistance values of capacitors and resistors vary due to fluctuations in the manufacturing process of the semiconductor integrated circuit, and the oscillation frequency of the CR oscillation circuit varies. Therefore, when checking the operation of a semiconductor integrated circuit at the stage of a wafer or a chip, trimming of a resistance value or a capacitance value is performed to correct variation in oscillation frequency.
[0003]
The conventional trimming method includes a step of inputting trimming data into a semiconductor integrated circuit through a serial interface and measuring the oscillation frequency of the CR oscillation circuit while performing trimming to determine whether or not the CR oscillation circuit is acceptable until an appropriate oscillation frequency is obtained. It was a repetition. However, according to this trimming method, a considerable amount of time is required to measure the frequency. Therefore, there is a problem that as the number of times of trimming increases, the time required for operation check increases, and the manufacturing cost greatly increases. Was.
[0004]
[Problems to be solved by the invention]
The present invention has been made in view of the above problems, and in a semiconductor integrated circuit having a built-in CR oscillation circuit, the number of times of measuring an oscillation frequency when trimming a resistance value or a capacitance value is reduced, The aim is to reduce manufacturing costs.
[0005]
[Means for Solving the Problems]
In order to solve the above problems, a semiconductor integrated circuit according to a first aspect of the present invention includes a trimming circuit that selects at least one resistor or capacitor from among a plurality of resistors or capacitors based on trimming data, and a trimming circuit. A CR oscillation circuit that performs an oscillating operation using at least one resistor or capacitor selected by the counter, a counter that counts an output signal of the CR oscillation circuit during a predetermined period, and a counter that counts an output signal of the CR oscillation circuit by a predetermined value. A determination circuit for determining whether the current value is within a predetermined range; a memory for storing trimming data corresponding to a count value determined by the determination circuit to be within a predetermined range; and, in a test mode, the trimming circuit includes a plurality of resistors. Or, generate trimming data so that capacitors are selected in a predetermined order, and switch to normal mode. Te comprises a trimming control circuit for controlling the trimming circuit with the trimming data stored in the memory.
[0006]
Here, the determination circuit outputs trimming data corresponding to the count value determined to be within the predetermined range as parallel data, and the semiconductor integrated circuit converts the parallel data output from the determination circuit into serial data. A data conversion circuit for supplying the data to the memory may be further provided.
[0007]
In addition, a semiconductor integrated circuit according to a second aspect of the present invention includes a trimming circuit that selects at least one resistor or capacitor from a plurality of resistors or capacitors based on trimming data, and at least one selected by the trimming circuit. A CR oscillation circuit that performs an oscillating operation using two resistors or capacitors, a counter that counts the output signal of the CR oscillation circuit during a predetermined period, and counts the number of measurements, and a count value of the output signal of the CR oscillation circuit A determination circuit for determining whether the count value is within a predetermined range; a memory for storing the number of measurements when the determination circuit determines that the count value of the output signal of the CR oscillation circuit is within the predetermined range; In such a case, the trimming circuit selects a plurality of resistors or capacitors in a predetermined order. It generates data, in the normal mode, and a trimming control circuit for generating a trimming data based on the number of measurements stored in the memory.
[0008]
Here, the semiconductor integrated circuit may further include a latch circuit that latches data indicating the number of measurements output from the counter and supplies the data to the memory according to the determination result obtained by the determination circuit.
[0009]
In the above, the trimming control circuit controls the trimming circuit so as to select at least one resistor having a predetermined resistance value from among the plurality of resistors when shifting to the test mode, and thereafter outputs the output of the CR oscillation circuit. When the count value of the signal is smaller than the lower limit of the predetermined range, the trimming circuit is controlled to reduce the resistance value, and when the count value of the output signal of the CR oscillation circuit is larger than the upper limit of the predetermined range. Alternatively, the trimming circuit may be controlled so as to increase the resistance value. In particular, when shifting to the test mode, at least one resistor having the Nth or (N + 1) th resistance value is selected from the 2N resistance values, or (2N + 1) resistors are selected. It is desirable to control the trimming circuit so as to select at least one resistor having the (N + 1) th magnitude resistance value from among the above resistance values.
[0010]
A method of manufacturing a semiconductor integrated circuit according to a first aspect of the present invention includes a CR oscillation circuit that performs an oscillating operation using at least one resistor or capacitor selected from a plurality of resistors or capacitors based on trimming data. , A counter, a determination circuit, a memory, and a trimming control circuit, wherein the semiconductor integrated circuit is placed in a test mode and a clock signal is supplied (a); (B) counting the output signal of the CR oscillation circuit by a counter during a predetermined period determined based on a clock signal while selecting a plurality of resistors or capacitors in a predetermined order under the control of (b). (C) determining by a determination circuit whether or not the count value of the output signal of the circuit is within a predetermined range; Comprises a step (d) which stores trimming data in the memory as data used to select a resistor or capacitor in the normal mode corresponding to the count value is determined to be within a predetermined range.
[0011]
Further, in the method of manufacturing a semiconductor integrated circuit according to the second aspect of the present invention, there is provided a CR oscillation device that performs an oscillating operation using at least one resistor or capacitor selected from a plurality of resistors or capacitors based on trimming data. A method for manufacturing a semiconductor integrated circuit including a circuit, a counter, a determination circuit, a memory, and a trimming control circuit, wherein the semiconductor integrated circuit is placed in a test mode and a clock signal is supplied (a); While selecting a plurality of resistors or capacitors in a predetermined order under the control of the control circuit, during a predetermined period determined based on the clock signal, the output signal of the CR oscillation circuit is counted by a counter, and the number of times of measurement is counted. Step (b) of counting, and whether or not the count value of the output signal of the CR oscillation circuit is within a predetermined range (C) determining the number of measurements when the determination circuit determines that the count value of the output signal of the CR oscillation circuit is within a predetermined range by selecting a resistor or a capacitor in the normal mode; (D) storing in a memory as data to be used.
[0012]
In the above, the step (b) is a step (b1) of selecting at least one resistor having a predetermined resistance value from a plurality of resistors, and the count value of the output signal of the CR oscillation circuit is a lower limit value of a predetermined range. The step (b2) of reducing the resistance value when the resistance value is smaller than the threshold value and the step (b3) of increasing the resistance value when the count value of the output signal of the CR oscillation circuit is larger than the upper limit value of the predetermined range. It may be included. In particular, in the step (b1), at least one resistor having an Nth or (N + 1) th magnitude resistance value is selected from the 2N resistance values, or (2N + 1) resistance values are selected. It is desirable to select at least one resistor having a (N + 1) th magnitude resistance value from among the values.
[0013]
According to the present invention, in the test mode, the output signal of the CR oscillation circuit is counted while changing the value of the resistor or the capacitor by the trimming circuit, and the count value determined to be within the predetermined range is stored in the memory. In the normal mode, by controlling the trimming circuit based on the count value stored in the memory, the number of times the oscillation frequency is measured when trimming the resistance value or the capacitance value is reduced, and the manufacturing cost is reduced. can do.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the same components are denoted by the same reference numerals, and description thereof will be omitted.
FIG. 1 shows a configuration of a semiconductor integrated circuit according to the first embodiment of the present invention. As shown in FIG. 1, the semiconductor integrated circuit 10 includes a CR oscillation circuit 11 whose oscillation frequency is determined by a capacitor and a resistor. As a type of the CR oscillation circuit, a bridge type oscillation circuit and a phase shift type oscillation circuit are known. For example, in the Wien bridge oscillator circuit, with a resistance value R of the capacitor C and a resistor of the capacitor, the oscillation frequency f ₀ is given by the following equation.
f ₀ = 1 / (2πCR)
As shown in this equation, when the resistance value R decreases, the oscillation frequency f ₀ increases, and when the resistance value R increases, the oscillation frequency f ₀ decreases. Therefore, in the present embodiment, in order to adjust the oscillation frequency f ₀ of the CR oscillation circuit 11 uses a trimming circuit 16 to change the resistance value R. The trimming circuit 16 selects at least one of the plurality of resistors based on the trimming data. The CR oscillation circuit 11 performs an oscillation operation using at least one resistor selected by the trimming circuit 16.
[0015]
In addition, the semiconductor integrated circuit 10 includes a gate circuit 12, a counter 13, a determination circuit 14, a trimming decoder 15, a data conversion circuit 17, and a trimming memory 18. When the test mode signal is supplied and the semiconductor integrated circuit 10 enters the test mode, the trimming decoder 15 generates trimming data so that the trimming circuit 16 selects a plurality of resistors in a predetermined order. When the resistance value R is set by the trimming circuit 16, the gate circuit 12 sets the count period of the counter 13 using the external reference clock signal. The counter 13 counts the output signal of the CR oscillation circuit 11 during this counting period. The determination circuit 14 determines whether or not the count value is within a predetermined range, and outputs trimming data corresponding to the count value determined to be within the predetermined range as parallel data. The data conversion circuit 17 converts the parallel data output from the determination circuit 14 into serial data and supplies the serial data to the trimming memory 18. The trimming memory 18 stores the serial data.
[0016]
Thus, when the resistance value R is determined for realizing the oscillation frequency f ₀ within a predetermined range, the semiconductor integrated circuit 10 is to be used in the normal mode. In the normal mode, the trimming decoder 15 controls the trimming circuit using the trimming data stored in the trimming memory 18.
[0017]
Next, a method for manufacturing a semiconductor integrated circuit according to the first embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a flowchart illustrating a method for manufacturing a semiconductor integrated circuit according to the first embodiment of the present invention. The process shown in FIG. 2 is performed at the end of the entire manufacturing process. As hardware, data for giving a proper oscillation frequency to a completed wafer or chip is stored and actually oscillated. To check the oscillation frequency.
[0018]
First, a test mode signal is supplied to the semiconductor integrated circuit 10 to put the semiconductor integrated circuit 10 in the test mode. In step S11, the gate circuit 12 sets a count period by supplying an external reference clock to the semiconductor integrated circuit 10. During this counting period, the counter 13 counts the output signal of the CR oscillation circuit 11 (Step S12). In step S13, the determination circuit 14 determines whether the count value is within a predetermined range. If the result of determination is that the count value is not within the predetermined range, the process proceeds to step S14, where the trimming circuit 16 performs trimming by changing the resistance value. Thereafter, steps S11 to S13 are repeated. On the other hand, if the count value is within the predetermined range, the process proceeds to step S15, and trimming data corresponding to the count value is written to the trimming memory 18. After that, the semiconductor integrated circuit is shifted from the test mode to the normal mode, and in step S17, the oscillation frequency of the CR oscillation circuit 11 is measured.
[0019]
According to the present embodiment, the appropriate trimming data is automatically determined in the semiconductor integrated circuit and written into the trimming memory, so that the measurement of the oscillation frequency using the measuring instrument only needs to be performed once finally. The time required for testing an integrated circuit can be significantly reduced.
[0020]
Next, a second embodiment of the present invention will be described.
FIG. 3 shows a configuration of a semiconductor integrated circuit according to the second embodiment of the present invention. In the present embodiment, the semiconductor integrated circuit 20 includes a determination circuit 21 and a latch circuit 22 instead of the determination circuit 14 and the data conversion circuit 17 shown in FIG.
[0021]
The counter 13 counts the output signal of the CR oscillation circuit 11 and counts the number of measurements during the counting period. The determination circuit 21 determines whether or not the count value of the output signal of the CR oscillation circuit 11 is within a predetermined range, and outputs a determination signal to the latch circuit 22 when determining that the count value is within the predetermined range. . The latch circuit 22 latches the data indicating the number of measurements output from the counter 13 and supplies the data to the trimming memory 18 in response to the determination signal. The trimming memory 18 stores this data.
[0022]
Thus, when the resistance value R for realizing the oscillation frequency f ₀ within a predetermined range is determined, the semiconductor integrated circuit 20 is to be used in the normal mode. In the normal mode, the trimming decoder 15 generates trimming data based on the data stored in the trimming memory 18.
[0023]
Next, a method for manufacturing a semiconductor integrated circuit according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a flowchart showing a method for manufacturing a semiconductor integrated circuit according to the second embodiment of the present invention.
[0024]
First, a test mode signal is supplied to the semiconductor integrated circuit 20 to put the semiconductor integrated circuit 20 into the test mode. In step S21, the trimming decoder 15 selects at least one resistor having a predetermined resistance value from among a plurality of resistors. Here, as the predetermined resistance value, assuming that N is a natural number, the resistance value is the Nth or (N + 1) th resistance value out of 2N resistance values, or the (2N + 1) resistance value. It is desirable that the resistance value be the (N + 1) th resistance value.
[0025]
In step S22, the gate circuit 12 sets a count period by supplying an external reference clock to the semiconductor integrated circuit 20. During this counting period, the counter 13 counts the output signal of the CR oscillation circuit 11 (Step S23). In step S24, the determination circuit 21 determines whether the count value is within a predetermined range. If the result of the determination is that the count value is not within the predetermined range, the process proceeds to step S25.
[0026]
In step S25, the trimming decoder 15 changes the resistance value based on the count value. For example, when the count value of the output signal of the CR oscillation circuit 11 is smaller than the lower limit value of the predetermined range, the trimming decoder 15 reduces the resistance value and sets the count value of the output signal of the CR oscillation circuit 11 to the predetermined value. If the resistance value is larger than the upper limit of the range, the resistance value may be increased. Thereafter, steps S22 to S24 are repeated. In this way, in step S21, the Nth or (N + 1) th resistance value is set from among the 2N resistance values, or the (N + 1) th resistance value is selected from among the (2N + 1) resistance values. When the (N + 1) th resistance value is set, the number of repetitions of steps S22 to S24 can be limited to about half of the total number of resistance values.
[0027]
On the other hand, if the count value is within the predetermined range, the process proceeds to step S26, where the latch circuit 22 latches the data indicating the number of measurements, and if necessary, initializes the count of the output signal of the CR oscillation circuit 11. The information is written in the trimming memory 18 together with information indicating whether the value is too large or too small. The trimming decoder 15 can obtain trimming data that gives an appropriate oscillation frequency based on the data. Thereafter, the semiconductor integrated circuit is shifted from the test mode to the normal mode, and in step S27, the oscillation frequency of the CR oscillation circuit 11 is measured.
[0028]
In the above embodiment, the case where the resistor that determines the oscillation frequency of the CR oscillation circuit is trimmed has been described. However, the capacitor that determines the oscillation frequency may be similarly trimmed.
[0029]
【The invention's effect】
As described above, according to the present invention, in a semiconductor integrated circuit having a built-in CR oscillation circuit, the number of times the oscillation frequency is measured when trimming the resistance value or the capacitance value is reduced, and the manufacturing cost is reduced. be able to.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration of a semiconductor integrated circuit according to a first embodiment of the present invention.
FIG. 2 is a flowchart illustrating a method for manufacturing a semiconductor integrated circuit according to the first embodiment of the present invention.
FIG. 3 is a block diagram illustrating a configuration of a semiconductor integrated circuit according to a second embodiment of the present invention.
FIG. 4 is a flowchart illustrating a method for manufacturing a semiconductor integrated circuit according to a second embodiment of the present invention.
[Explanation of symbols]
10, 20 Semiconductor integrated circuit 11 CR oscillation circuit 12 Gate circuit 13 Counter 14, 21 Judgment circuit 15 Trimming decoder 16 Trimming circuit 17 Data conversion circuit 18 Trimming memory 22 Latch circuit

Claims (10)

A trimming circuit for selecting at least one resistor or capacitor from the plurality of resistors or capacitors based on the trimming data;
A CR oscillation circuit that performs an oscillation operation using at least one resistor or capacitor selected by the trimming circuit;
A counter for counting an output signal of the CR oscillation circuit during a predetermined period;
A determination circuit for determining whether or not the count value of the output signal of the CR oscillation circuit is within a predetermined range;
A memory for storing trimming data corresponding to the count value determined by the determination circuit to be within a predetermined range,
In a test mode, the trimming circuit generates trimming data so as to select the plurality of resistors or capacitors in a predetermined order. In a normal mode, the trimming circuit uses the trimming data stored in the memory. A trimming control circuit for controlling
A semiconductor integrated circuit comprising: The determination circuit outputs trimming data corresponding to the count value determined to be within a predetermined range as parallel data,
2. The semiconductor integrated circuit according to claim 1, further comprising a data conversion circuit that converts parallel data output from the determination circuit into serial data and supplies the serial data to the memory. A trimming circuit for selecting at least one resistor or capacitor from the plurality of resistors or capacitors based on the trimming data;
A CR oscillation circuit that performs an oscillation operation using at least one resistor or capacitor selected by the trimming circuit;
A counter that counts the output signal of the CR oscillation circuit during a predetermined period and counts the number of measurements;
A determination circuit for determining whether or not the count value of the output signal of the CR oscillation circuit is within a predetermined range;
A memory for storing the number of measurements when the determination circuit determines that the count value of the output signal of the CR oscillation circuit is within a predetermined range;
In the test mode, the trimming circuit generates trimming data so as to select the plurality of resistors or capacitors in a predetermined order, and in the normal mode, trimming data based on the number of measurements stored in the memory. A trimming control circuit to generate;
A semiconductor integrated circuit comprising: 4. The semiconductor integrated circuit according to claim 3, further comprising a latch circuit that latches data indicating the number of measurements output from the counter according to a determination result obtained by the determination circuit and supplies the data to the memory. The trimming control circuit controls the trimming circuit so as to select at least one resistor having a predetermined resistance value from among a plurality of resistors when a transition is made to a test mode. When the count value of the signal is smaller than the lower limit value of the predetermined range, the trimming circuit is controlled so as to reduce the resistance value, and the count value of the output signal of the CR oscillation circuit is larger than the upper limit value of the predetermined range. The semiconductor integrated circuit according to claim 1, wherein the trimming circuit is controlled to increase the resistance value when the value is larger. When the trimming control circuit shifts to the test mode, the trimming control circuit selects at least one resistor having an Nth or (N + 1) th resistance value from the 2N resistance values, or 6. The semiconductor integrated circuit according to claim 5, wherein the trimming circuit is controlled so as to select at least one resistor having a (N + 1) th resistance value from among (2N + 1) resistance values. Includes a CR oscillation circuit that performs an oscillating operation using at least one resistor or capacitor selected from a plurality of resistors or capacitors based on the trimming data, a counter, a determination circuit, a memory, and a trimming control circuit A method of manufacturing a semiconductor integrated circuit,
Placing the semiconductor integrated circuit in a test mode and supplying a clock signal (a);
Counting the output signal of the CR oscillation circuit by the counter during a predetermined period determined based on a clock signal while selecting the plurality of resistors or capacitors in a predetermined order under the control of the trimming control circuit. (B),
(C) determining by the determination circuit whether or not the count value of the output signal of the CR oscillation circuit is within a predetermined range;
(D) storing trimming data corresponding to the count value determined to be within a predetermined range in the memory as data used for selecting a resistor or a capacitor in a normal mode;
A production method comprising: Includes a CR oscillation circuit that performs an oscillating operation using at least one resistor or capacitor selected from a plurality of resistors or capacitors based on the trimming data, a counter, a determination circuit, a memory, and a trimming control circuit A method of manufacturing a semiconductor integrated circuit,
Placing the semiconductor integrated circuit in a test mode and supplying a clock signal (a);
While selecting the plurality of resistors or capacitors in a predetermined order under the control of the trimming control circuit, during a predetermined period determined based on a clock signal, an output signal of the CR oscillation circuit is counted by the counter. (B) counting the number of measurements,
(C) determining by the determination circuit whether or not the count value of the output signal of the CR oscillation circuit is within a predetermined range;
The number of measurements when the determination circuit determines that the count value of the output signal of the CR oscillation circuit is within a predetermined range is stored in the memory as data used for selecting a resistor or a capacitor in a normal mode. Step (d),
A production method comprising: Step (b)
(B1) selecting at least one resistor having a predetermined resistance value from among the plurality of resistors;
(B2) reducing the resistance value when the count value of the output signal of the CR oscillation circuit is smaller than a lower limit value of a predetermined range;
(B3) increasing the resistance value when the count value of the output signal of the CR oscillation circuit is larger than an upper limit value of a predetermined range;
The production method according to claim 7, comprising: Step (b1) selects at least one resistor having an Nth or (N + 1) th magnitude resistance value from the 2N resistance values, or selects (2N + 1) resistance values. The manufacturing method according to claim 9, further comprising selecting at least one resistor having a (N + 1) th magnitude resistance value from among them.

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