JP2007227478A - Method of manufacturing semiconductor chip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor chip manufacturing method for manufacturing a small, inexpensive, and high-precision semiconductor chip. <P>SOLUTION: The method of manufacturing the semiconductor chip is composed of a step (S1) for forming a semiconductor device by performing diffusion and vapor deposition or the like on a wafer, a step (S2) for performing vapor deposition and processing of an aluminum film, a step (S3) for measuring a resistance value R<SB>A</SB>of an output constituting the semiconductor device, a step (S4) for selecting an optimum mask on the basis of the measured resistance value R<SB>A</SB>, a step (S5) for forming an interlayer insulating film, a step (S6) for forming a through-hole, and a step (S7) for performing vapor deposition and processing of a second aluminum film by using a selected mask. A reference voltage applied to the output is adjusted by mutually connecting and wiring among some resistors at a reference voltage for applying a constant voltage to the output in the S7. In this way, adjustment is executed in the middle of a product manufacturing process not after completion of the product manufacturing process. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor chip, in which an output section for outputting a constant current is formed on a semiconductor element.

  It is widely practiced to form a semiconductor chip by forming wiring (mainly aluminum wiring) on a semiconductor element subjected to diffusion treatment or the like and cutting it. In this diffusion treatment, in order to manufacture P-type and N-type semiconductors, impurities are usually diffused by thermal diffusion treatment after the addition of impurities by ion implantation.

  By the way, it is known that the semiconductor element has a demerit that the absolute accuracy of resistance or the like is not good. In particular, when the thermal diffusion process is performed, the resistance of individual semiconductor elements tends to vary, and this tendency is noticeable.

  For this reason, in order to obtain high-accuracy characteristics in a semiconductor circuit using a semiconductor element, after the chip is formed using the semiconductor element, an adjustment action is performed on the chip, or other components are attached to the chip. It is necessary to install it.

  For example, in order to obtain a constant current, a constant current is obtained with a voltage and resistance generated by a constant voltage circuit. In the case of a semiconductor element, it is well known that a stable constant voltage (constant potential) such as a band gap reference voltage can be generated. However, since dispersion occurs due to diffusion, absolute accuracy cannot be obtained for the resistance. For this reason, it is necessary to perform on-chip adjustment or to use an external resistor with high accuracy.

  On-chip adjustments include laser trimming (a method of finely adjusting circuit characteristics by processing the shape of a resistor with laser light), adjustment to open the circuit with a fuse, and short circuit by Zener Zap trimming. It is conceivable to make adjustments. However, when such an adjustment is performed, there is a possibility that the open part may be reconnected or the shorted part may be disconnected again due to deterioration due to aging. In addition, by performing such an adjustment action, the chip cost is increased.

  Further, in the case where the adjustment by the selection pad is performed as the adjustment on the chip, since the logic circuit and the selection pad are provided on the chip, the chip size is increased. This will be described with an example.

  FIG. 4 shows a schematic plan view of an example of a conventional chip (semiconductor chip) 70. The chip 70 constitutes various circuits for each region, and each circuit has a different function. The configuration of the chip 70 shown in FIG. 4 is classified into a current adjusting unit 80, an output unit 82, a selection pad 96, and a plurality of functional units 74 such as a current supply circuit and a constant voltage circuit (not shown).

Here, the output unit 82 to utilize the reference voltage V _A, the current value flowing through the reference voltage V _A is, for changing the resistance value R _A of the resistance portion 108 of the output unit 82, is applied to the output section 82 The reference voltage needs to be adjusted. For this reason, the current adjustment unit 80 includes a reference voltage unit 79 and a logic circuit unit 81, and each resistance unit 98 of the reference voltage unit 79 is configured by a selection control unit 83 included in the logic circuit unit 81 as shown in FIG. By controlling the short-circuit and open-circuit of both ends, the processing of whether or not both ends of each resistance of the reference voltage unit 79 are short-circuited is performed.

  As described above, when adjustment is performed using the selection pad 96, the current adjustment unit 80 of the chip 70 includes the logic circuit unit 81 and the selection pad 96 in addition to the reference voltage unit 79. For this reason, since the size of the chip 70 is increased, the chip cost is increased, and the restriction on the arrangement position of the pad causes a great restriction on the chip layout.

  In addition, when an external resistor is used, the product size increases and the cost increases.

  In view of the above fact, an object of the present invention is to provide a semiconductor chip manufacturing method capable of manufacturing a highly accurate small and inexpensive semiconductor chip.

  The invention according to claim 1 includes an output unit that outputs a constant current when a reference voltage is applied, and a plurality of resistance units, and divides the input voltage and applies the reference voltage to the output unit. A first step of forming a reference voltage portion on the wafer, a measurement step of measuring the resistance value of the output portion, and a plurality of types of masks corresponding to the resistance value are prepared, and based on the resistance value A selection step of selecting an optimum mask from the plurality of types of masks, and a second step of adjusting the reference voltage using the selected mask.

  The above wiring is often formed by patterning an aluminum film.

  In the invention according to the first aspect, the measurement step, the selection step, and the second step are not performed after the completion of the product manufacturing process, but in the middle of the product manufacturing process such as after the diffusion step. Is going. Therefore, the constant current accuracy required for the product specifications can be satisfied by a simple method, and a highly accurate small and inexpensive semiconductor chip can be manufactured.

  As an example, in the first step, the first aluminum film is deposited and processed for wiring of the entire semiconductor chip. In the second step, the first aluminum film is deposited and processed. Alternatively, the reference voltage may be adjusted by performing a vapor deposition / processing step of a second aluminum film dedicated to short circuit, which is set separately.

  Since the present invention is configured as described above, a highly accurate small and inexpensive semiconductor chip can be manufactured.

  Hereinafter, embodiments will be described and embodiments of the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic plan view of a chip (semiconductor chip) 10 according to an embodiment of the present invention. The chip 10 constitutes various circuits for each region, and each circuit has a different function.

  The region of the chip 10 shown in FIG. 1 is classified into a reference voltage unit 20, an output unit 22, and a plurality of functional units 12 such as a current supply circuit and a constant voltage circuit (not shown).

  The manufacturing process of the chip 10 is classified into a pre-process and a post-process.

  In the previous step, an oxide film is formed on a silicon wafer, a photoresist film is formed, exposure processing and development processing are performed, and etching processing is performed. Then, impurities are implanted to form aluminum wiring.

  In the post-process, the silicon wafer that has completed the pre-process is diced, and wiring is performed by wire bonding.

  Hereinafter, manufacturing the chip 10 will be described with reference to the flowchart of FIG. In the following chip manufacturing process, the part related to the present invention will be mainly described, and other well-known techniques will be described only as necessary.

  In the present embodiment, a semiconductor element is formed by performing a diffusion process or the like on the wafer (step S1). In many cases, diffusion treatment is performed by thermal diffusion. Further, an aluminum film is formed and processed by etching to form a wiring (step S2). As a result, the reference voltage unit 20, the output unit 22, and other functional units are formed. A plurality of resistor portions 28 are formed in the reference voltage portion 20.

Thereafter, element characteristics are measured. In this measurement, the resistance value _RA of the resistance unit 38 (see FIG. 3) constituting the output unit 22 is measured (step S3). In the measurement of the resistance value _RA , the current value I that flows when the reference voltage _VA is applied to the output unit 22 is measured and obtained by the following equation (1).

R _A = V _A / I (1)
This expression (1) is an expression based on a simple Ohm's law.

Further, an optimum mask is selected from a plurality of types of masks prepared in advance based on the obtained resistance value _RA (step S4). Then, formation of an interlayer insulating film (step S5), formation of a through hole (step S6), vapor deposition and processing (patterning) of an aluminum film (second aluminum film), and performing some specific operations in the reference voltage unit 20 The reference voltage _VA applied from the reference voltage unit 20 to the output unit 22 is adjusted by connecting and wiring between the resistors (step S7). In this case, the mask selected in step S4 is used.

By adjusting the reference voltage V _A in this way, the accuracy of the constant current I flowing through the output unit 22 can be increased to a target accuracy.

  In FIG. 3, the connection of the resistor 28 of the reference voltage unit 20 in step S7 is represented as a switch, and the switch ON indicates that the resistor is short-circuited and not connected. The resistance values of the resistance unit 28 may be the same or different from each other. The arrangement of the resistance portion 28 is not limited to being in series, and may be variously changed.

In the present embodiment, as described above, the resistance value _RA is measured during the product manufacturing process such as after the end of the diffusion process, not after the product manufacturing process (chip 10 manufacturing process) is completed. Then, an optimum mask is selected, and the reference voltage _VA applied to the output unit 22 is adjusted by short-circuiting some of the resistor units 28.

As a result, the accuracy of the current value I of the constant current flowing through the output unit 22 can be increased to the target accuracy regardless of variations in the resistance value _RA . Therefore, the product specifications can be satisfied by a simple method, and the highly accurate and inexpensive chip 10 can be manufactured.

  Further, as shown in FIG. 3, the configuration of the current adjustment unit can be only the reference voltage unit 20, and the chip 10 can be provided with no selection pad. Therefore, it is possible to obtain a chip 10 having an optimal size that is significantly reduced in size compared to the conventional example (see FIGS. 4 and 5). In addition, since the arrangement positions of the reference voltage unit 20, the output unit 22, and the plurality of functional units 12 can be changed as appropriate, the ratio of the vertical length to the horizontal length of the chip 10 can be changed as appropriate.

In addition, it is not necessary to newly add a processing process for adjusting the resistance value _RA to the conventional process, and the chip 10 can be reduced in size as described above, so that the cost can be reduced. it can.

Note that a process monitor capable of confirming the resistance value _RA may be arranged on the wafer, so that it is not necessary to measure the resistance characteristic of the semiconductor element itself for which the reference voltage _VA is to be adjusted.

In the present embodiment, in step S7, the aluminum film (second aluminum film) is vapor-deposited and processed (patterning), and a plurality of specific resistors in the reference voltage unit 20 are connected and connected to each other. Although the adjustment of the voltage _VA is performed, in the present invention, the adjustment of the reference voltage _VA is not limited to connection wiring, and other adjustments such as formation of a resistor may be performed.

  The embodiments of the present invention have been described with reference to the embodiments. However, the above embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. Needless to say, the scope of rights of the present invention is not limited to the above embodiment.

In the Example of one Embodiment of this invention, it is a typical top view which shows that the chip | tip was reduced in size because the component of the chip | tip decreased. It is explanatory drawing which shows the process performed by one Embodiment of this invention. In one Embodiment of this invention, it is explanatory drawing which shows that the constant current precision of a chip | tip is satisfy | filled by adjustment of a reference voltage part. It is a typical top view which shows an example of the conventional chip | tip. It is explanatory drawing which shows satisfy | filling the constant current precision of a chip | tip conventionally.

Explanation of symbols

10 chips (semiconductor chips)
20 Reference voltage part 22 Output part 28 Resistor part 70 Chip (semiconductor chip)
79 Reference voltage section 82 Output section 98 Resistance section

Claims (1)

An output unit that outputs a constant current when a reference voltage is applied, and a reference voltage unit that includes a plurality of resistance units and divides the input voltage and applies the reference voltage to the output unit are formed on the wafer. A first step of
A measuring step of measuring a resistance value of the output unit;
A plurality of types of masks corresponding to the resistance value are prepared, and a selection step of selecting an optimal mask from the plurality of types of masks based on the resistance value;
A second step of adjusting the reference voltage using the selected mask;
A method for manufacturing a semiconductor chip, comprising:

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