JP2003086831A - Semiconductor device production method - Google Patents

Abstract

(57) [Problem] To efficiently produce semiconductor devices having predetermined characteristics and reduce inventory. In a production process of manufacturing a semiconductor device by assembling two chips into one package, a chip (semiconductor light emitting chip) to be assembled is given a predetermined characteristic value by using wafer test information of the chip to be assembled. A is ranked on a wafer or lot basis, and the chip is ranked on a wafer or lot basis with a predetermined characteristic value B using wafer test information of the other chip (semiconductor light receiving chip). A predetermined characteristic value C of the semiconductor device is obtained by assembling one chip of the rank (semiconductor light emitting chip) and the other chip of another specific rank (semiconductor light receiving chip) in wafer units or lot units.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device including a plurality of chips.

[0002]

2. Description of the Related Art Conventionally, when a semiconductor device having predetermined characteristic values is produced, a plurality of chips are assembled into a package,
A characteristic inspection was conducted after forming a finished product to select semiconductor devices having predetermined characteristic values.

[0003]

By the way, among semiconductor devices, in a semiconductor device in which a semiconductor light emitting chip and a semiconductor light receiving chip are assembled into one package,
There are variations in the characteristics of the semiconductor light emitting chip and variations in the characteristics of the semiconductor light receiving chip. For this reason, when the semiconductor light emitting chip and the semiconductor light receiving chip are combined into one semiconductor device, the characteristic variations become extremely large due to the synergistic effect of the variations of the respective chips, and when a semiconductor device having a predetermined characteristic is produced. Yield is very poor.

A specific example will be described using a photocoupler in which an infrared light emitting diode chip is used as a semiconductor light emitting chip and a phototransistor chip is used as a semiconductor light receiving chip.

As shown in FIG. 1, the photocoupler includes an infrared light emitting diode chip 2 and a phototransistor chip 3.
Are die-bonded to the frames 4 and 5, respectively, and are assembled so that the light emitting surface of the infrared light emitting diode chip 2 and the light receiving surface of the phototransistor chip 3 face each other, and the infrared light emitting diode chip 2 and the phototransistor chip are assembled. Infrared light is radiated by an electric current applied to the infrared light emitting diode chip 2 from the outside, and the phototransistor chip 3 converts the infrared light into a current. As a result, the semiconductor device transmits an electric signal in a state where the input and the output are electrically insulated from each other. A semitransparent resin 6 and an opaque resin 7 are molded on the photocoupler 1 shown in FIG. 1 as primary and secondary molding resins.

In such a photocoupler 1 as shown in FIG. 2, when a current Iin flows to the input side connected to the infrared light emitting diode chip 2, a current Iout flows to the output side connected to the phototransistor chip 3. Can transmit electrical signals.

In the photocoupler, the ratio of the current Iout to the current Iin, that is, (Iout / Iin) ×
100 is called a current conversion rate (hereinafter referred to as CTR), and the unit is%.

As the photocoupler, one having a CTR within a specific range is used depending on the application. The smaller the variation of the CTR, the easier the circuit design.
It is desired that there is little variation in TR. Also, depending on the application, not only the CTR variation but also the CTR
It may be specified in a narrow range.

However, the CTR is the light output value of the infrared light emitting diode chip and the hF of the phototransistor chip.
It depends on the combination with E (current amplification factor). The optical output value of these infrared light emitting diode chips and the hFE of the phototransistor chips inevitably vary within a certain range in actual production. For this reason, the CTR of the photocoupler in which the optical output value of the infrared light emitting diode chip and the phototransistor chip are combined has a larger variation, and it is difficult to suppress the CTR within a specific CTR range. The yield will be poor if selected.

For example, in the production of infrared light emitting diode chips, when n wafers make up one batch and epitaxial growth is performed in batches, the light output distribution of the chips of each wafer in the batch is shown in FIG. As shown in the figure, the same wafer is relatively small, and the variations between the wafers are generally large, and the variations in the optical output values of the chips in the batch are large as shown in FIG.

On the other hand, the distribution of the hFE of the phototransistor in the wafer and in the batch also varies as shown in FIGS. 5 and 6, and when these chips are randomly combined to produce a photocoupler, for example, FIG. As shown
The width of the CTR distribution increases. Therefore, in the past,
Products were supplied to users by ranking according to CTR. Note that in FIG. 7, the CTR is 10% to 125%.
The example shows that these are classified and sorted into five ranks 1 to 5 with a width of 20% by CTR.

However, in the system in which the finished products are ranked and the products are supplied, the user's request is a specific CT.
Often concentrated on R rank, for example, when only rank 2 is required in FIG. 7, the conventional production method has a take rate of about 25%, and the remaining 75% remains as inventory. The production efficiency becomes poor.

The present invention has been made to improve such a point. When assembling two chips into one device to produce a semiconductor device, the semiconductor device having predetermined characteristics can be produced efficiently. It is an object of the present invention to provide a method for manufacturing a semiconductor device that can be manufactured and can be reduced in inventory.

[0014]

According to the present invention, in a production method for assembling two chips into one device to produce a semiconductor device, the wafer test data of one of the chips to be assembled is used to determine that chip. Characteristic value A
And the wafer is divided into ranks on a wafer-by-wafer or lot-by-lot basis, and the wafer test data of the other chip is used to rank the chip on a wafer-by-wafer or lot-by-lot basis with a predetermined characteristic value B to separate it from one chip of a specific rank. Is characterized by obtaining the predetermined characteristic value C of the semiconductor device by assembling the other chip of the specific rank of (1) in a wafer unit or a lot unit.

Further, according to the present invention, in a production method for producing a semiconductor device by assembling two chips into one device, mapping information of a predetermined characteristic value A in a wafer test of one chip to be assembled and another Using the mapping information of the predetermined characteristic value B in the wafer test of the chips, one chip and the other chip which are the optimum chip combination are selected and assembled into one device, so that the predetermined characteristic value C of the semiconductor device is obtained. Is characterized by.

As a concrete mode of the present invention, there is a mode in which a semiconductor light emitting chip is used as the one chip and a semiconductor light receiving chip is used as the other chip to produce a semiconductor device.

Specific examples of the semiconductor light emitting chip used in the production of the semiconductor device in the present invention include a semiconductor infrared light emitting chip (infrared light emitting diode chip) and a semiconductor visible light emitting chip. Further, as a specific example of the semiconductor light receiving chip, a phototransistor, a photo Darlington transistor, a photothyristor, a phototriac, a photoMOS, a photo IC, or the like can be given.

Examples of the semiconductor device produced in the present invention include a photo coupler, a photo Darlington coupler, a photo thyristor coupler, a photo triac coupler, a photo MOS coupler, a photo IC coupler, and a photo interrupter.

As a specific example of the predetermined characteristic value A and the predetermined characteristic value B used in the present invention and the predetermined characteristic value C of the semiconductor device, the predetermined characteristic value A is the light output value of the semiconductor light emitting chip and the predetermined characteristic. The value B is hFE of the semiconductor light receiving chip, and the predetermined characteristic value C of the semiconductor device is CTR such as a photocoupler.
Can be mentioned.

The production method of the present invention will be described more specifically.

In the production method of the present invention, when a photocoupler including an infrared light emitting diode chip and a phototransistor chip is produced, the wafer is ranked according to the light output value of each wafer in the wafer test process of the infrared light emitting diode chip. As for the phototransistor chips, the wafers are ranked according to the hFE obtained in the wafer test process, while the infrared light emitting diode chip having a specific light output value and the phototransistor chip having a specific hFE are used as photocouplers. In advance, the relationship with the CTR obtained in the case of producing the CTR is obtained, and the infrared light emitting diode wafer and the phototransistor wafer having the optimum rank for producing the specific CTR are combined based on the information. Products of the required rank by making photo couplers It becomes possible to make without waste, it is possible to efficiently produce a photo-coupler with a specific CTR.

Further, in addition to the combination of wafers of the above-mentioned optimum rank, the light output value of the infrared light emitting diode and the mapping information of the hFE of the phototransistor are acquired in the wafer test process, and the mapping information is specified based on this mapping information. By combining the infrared light emitting diode chip and the phototransistor chip that are optimal for producing a photocoupler with a CTR of
The removal rate can be further increased.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below by taking production of a photocoupler as an example.

First, in the infrared light emitting diode wafer test process, the light output values of the chips in the wafer are measured, and the median value of the distribution of the light output values for each wafer is obtained. When the distribution of the median of the optical output values is taken for 5 to 10 batches (about 200 to 500) of wafers, the distribution as shown in FIG. 8 is obtained.

Regarding the hFE of the phototransistor,
In the wafer test process, hFE of the chips in the wafer is measured, and the median value of the distribution for each wafer is calculated. When the distribution of the median value of hFE is taken for 5 to 10 batches (about 200 to 500) of wafers, the distribution as shown in FIG. 9 is obtained. 8 and 9 show the median value of the light output value of the light emitting diode chip for each wafer and h of the phototransistor chip.
Data is acquired in advance as a representative of the distribution of FE for each wafer.

Next, based on the distribution data of FIGS. 8 and 9, the wafer rank is classified by the light output value of the infrared light emitting diode and the hFE of the phototransistor.

FIG. 10 shows the distribution of the median values of the optical outputs of the individual wafers of the infrared light emitting diodes as G1, G2, G3 and G.
The figure shows the case of being divided into five ranks of 4 and G5.

For example, five wafers of infrared light emitting diodes are inspected in a wafer test, and the median values of optical output data are [1.1], [1.25], [1.48], [1.
7] and [1.9] are obtained, these wafers are classified into rank G1, rank G2, rank G3, rank G4, and rank G5, respectively.

FIG. 11 shows the distribution of the median value of hFE of individual wafers of phototransistors as P1, P2, P3, P.
The figure shows the case of being divided into five ranks of 4 and P5.

In the present embodiment, both the infrared light emitting diode chip and the phototransistor chip are divided into five ranks, respectively.
Depending on R, the number of ranks may be increased or decreased. Further, the light output value of each rank or the width of hFE can be changed according to the production situation.

Although the median value is used for ranking the wafers, the light output value, the average value of hFE, or the center value may be used instead.

Since the CTR of the photocoupler is substantially determined by the light output value of the infrared light emitting diode chip and the hFE of the phototransistor chip, the relationship between the combination of the ranks of the wafers of these chips and the CTR is obtained in advance. .

Table 1 shows an example of the relationship between the optical output value and hFE and CTR when a photocoupler is made by combining an infrared light emitting diode chip and a phototransistor chip.

In Table 1, the light output value and hFE were selected as the central values of the respective ranks, and the CTR was obtained by experiment and calculation.

[0035]

[Table 1] Table 2 shows the optical output values, hFE, and CTR in Table 1 rewritten into ranks.

[0036]

[Table 2] In actual production, Table 2 may be used to find the rank combination of the light emitting and receiving chips required to produce a photo coupler of a specific CTR, but it is possible to obtain it in order to increase the target rank obtaining rate. Considering that the CTR should be as close as possible to the center value of each rank, use Table 3 below to show the wafers of infrared light emitting diodes and phototransistors required to produce a photocoupler of a particular CTR rank. The combination of.

[0037]

[Table 3] For example, in the case of producing rank 2 photocouplers, Table 3
Based on rank G3 infrared light emitting diode and rank P
It is advisable to combine the wafers of the phototransistors of No. 2 or the infrared light emitting diodes of the rank G1 and the wafers of the phototransistors of the rank P3.

FIG. 12 shows the CTR distribution of the photocoupler made by the above combination.

From the comparison between the CTR distribution of FIG. 12 and the CTR distribution (FIG. 7) produced by the conventional method, that is, the method of randomly combining the wafers which are not ranked, the production method of the present invention is adopted. , CTR distribution is significantly improved.

Here, in the above processing, the target CT
If there are wafers (or lots) that cannot be combined in the rank of R, the following measures may be taken.

The die bond of the wafer (or lot) is suspended until the next time.

Although the CTR rank is different from that of the target, if the rank is likely to be sold (not long-term inventory), it is produced, and if the rank is not likely to be sold, the wafer (or lot) is Hold die bond until next time.

The specific contents of the above processing will be described with reference to the flowchart of FIG.

Step Sa1: In the wafer test process, the light output value (predetermined characteristic value A) of the infrared light emitting diode chip is measured, and the representative value (median value) is obtained.

Step Sb1: In the wafer test process, hFE (predetermined characteristic value B) of the phototransistor chip is measured, and its representative value (median value) is obtained.

Step Sa2: The infrared light emitting diode chips are ranked by lot or wafer by the representative value of the light output value.

Step Sb2: The phototransistor chips are ranked by lot or wafer by the representative value of hFE.

Step Sc1: CTR of photo coupler
A combination that satisfies the required range of (the predetermined characteristic value C of the semiconductor device) is optimally selected from combinations of predetermined ranks.

Step Sc2: It is judged whether or not there is a lot or wafer combination that does not satisfy the required range of the CTR of the photocoupler. Die-bonding is performed for a combination of lots or wafers satisfying the required range of CTR (step Sc3).

If there is a lot or wafer that does not satisfy the required range of CTR, die bonding of the lot or wafer of the infrared light emitting diode chip is suspended until the next time (step Sa3). Further, the die bond is also held until the next time for the lot of the phototransistor chips or the wafer (step Sb3).

Next, the above processing will be specifically described with reference to the flowchart of FIG.

Step Sa11: In the wafer test process, the light output value (predetermined characteristic value A) of the infrared light emitting diode chip is measured, and the representative value (median value) is obtained.

Step Sb11: In the wafer test process, hFE (predetermined characteristic value B) of the phototransistor chip is measured, and its representative value (median value) is obtained.

Step Sa12: The infrared light emitting diode chips are ranked by lot or wafer by the representative value of the light output value.

Step Sb12: The phototransistor chips are ranked by lot or wafer by the representative value of hFE.

Step Sc11: CTR of photo coupler
A combination that satisfies the required range of (the predetermined characteristic value C of the semiconductor device) is optimally selected from combinations of predetermined ranks.

Step Sc12: CTR of photo coupler
It is determined whether there is a lot or a combination of wafers that does not satisfy the required range of. If there are lots or wafers that do not meet the required CTR range, step Sa
13. Go to step Sb13. Die-bonding is performed for a combination of lots or wafers satisfying the required range of CTR (step Sc13).

Step Sa13: CTR of photo coupler
For a lot or wafer of infrared light emitting diode chips that does not meet the required range of CTR, it is possible to determine that it will not be in long-term inventory when combined with similar phototransistor chips (chips that do not meet the required range of CTR) (appropriate If it is within the range of CTR), die bonding is performed. On the other hand, for a lot of infrared light emitting diode chips or a wafer having an inappropriate CTR range, die bonding is suspended until the next time.

Step Sb13: CTR of photo coupler
For a lot or wafer of phototransistor chips that does not meet the required range of CTR, a range of CTR that can be determined not to be in long-term inventory by combining with a similar infrared light emitting diode chip (chip that does not meet the required range of CTR) (appropriate If it is within the range of CTR), die bonding is performed. On the other hand, for a lot or wafer of phototransistor chips having an inappropriate CTR range, die bonding is suspended until the next time.

Next, another embodiment of the present invention will be described.

First, in order to produce a specific CTR, for example, a rank 2 photocoupler, rank G is used based on Table 3.
In the case of producing by using the infrared light emitting diode of 3 and the phototransistor wafer of rank P2, when the photocoupler is produced by randomly combining the chips included in each wafer, the CTR rank 2 is obtained by the combination of the chips. Something may come off.

To improve this, the light output value of the infrared light emitting diode chip and the hF of the phototransistor chip are
A method may be adopted in which the data maps of the wafer test of E are recorded in the computer and the infrared light emitting diode chips and the phototransistor chips are optimally combined by using these data maps. By doing so, a photocoupler having a required CTR can be produced.

For example, in CTR rank 2, CTR is 50%
In the case of producing the photocoupler of, the chips in the infrared light emitting diode wafer are GL as shown in FIG.
It is assumed that die bonding is performed in order from 1 to GLn, and the light output value (IL value) of the infrared light emitting diode chip of GL1 is 1.2.
In the case of 5, assuming that the CTR is close to the value given by the following formula (1), h of the required photo coupler is required.
The FE becomes 300.

CTR = (IL value × hFE) /7.5 (1) From the data map of the phototransistor wafer when die-bonding the phototransistor chip to be combined with this infrared light emitting diode chip GL1, The hFE of the PTm phototransistor chip shown in 16 is 300.
Then, skip the chips from PT1 to PTm-1,
By die-bonding and combining Tm chips, it is possible to produce a photocoupler with a CTR of approximately 50%.

Next, for the infrared light emitting diode chip of GL2, the hFE of the phototransistor chip required by the formula (1) is calculated, and the phototransistor chip having this value is also die-bonded by determining it by the data map. To produce. By centrally managing the series of calculations and die-bonding operations by a computer, it becomes possible to easily produce a specific photocoupler or a specific range of photocouplers.

In the above description, for the sake of convenience, when a phototransistor chip corresponding to a certain infrared light emitting diode chip is die-bonded, a chip having an appropriate hFE is selected, but this selection process takes time. Therefore, in practice, an optimum combination may be determined in advance and die-bonding may be performed based on the optimum combination.

The processing contents in that case will be described with reference to the flowchart of FIG.

Step Sa21: A data map on the wafer of the light output value of the infrared light emitting diode chip is created and stored in the computer.

Step Sb21: A data map on the wafer of the optical output value of the phototransistor chip is created and stored in the computer.

Step Sc21: Based on the data map of each chip, the computer causes the CTR of the photocoupler.
The optimum combination of each of the infrared light emitting diode chip and the phototransistor chip satisfying the required range of is determined based on the following relational expression (2).

C = f (A, B, R) (2) where C: predetermined characteristic value C (CTR), A: predetermined characteristic value A (light output value), B: predetermined Characteristic value B (hFE),
R: Coefficient peculiar to the type of semiconductor device Step Sc22: Die bonding is performed based on the combination determined by the computer.

In the above embodiments, the case where an infrared light emitting diode chip is used as a semiconductor light emitting chip and a phototransistor chip is used as a semiconductor light receiving chip has been described as an example, but the present invention is not limited to this. Without using a visible light emitting diode chip as a semiconductor light emitting chip, as a semiconductor light receiving chip, a photo diode chip, a photo Darling transistor chip, a photo thyristor chip, a photo triac chip, a photo MOS chip, and a photo IC chip in various combinations. It can be effectively applied to the production of couplers or photointerrupters.

Furthermore, the present invention can be applied to the production of other semiconductor devices whose characteristics are determined by a combination of a plurality of chips such as a DC stabilized power supply device in which a control IC chip and an output transistor chip are combined.

[0074]

As described above, according to the present invention,
Using the wafer test data of one chip (semiconductor light emitting chip) to be assembled, the chip is ranked according to a predetermined characteristic value A, and the other chip (semiconductor light receiving chip) is also ranked according to a predetermined characteristic value B. By dividing and assembling one chip of a specific rank and the other chip of another specific rank in a wafer unit or a lot unit, a predetermined characteristic value C of the semiconductor device can be obtained. It is possible to efficiently produce a semiconductor device having a predetermined characteristic, as compared with a production method, that is, a method in which when the characteristic values of the semiconductor device vary, the finished product is classified by rank.

Further, according to the present invention, mapping information of a predetermined characteristic value A of a wafer test on one chip (semiconductor light emitting chip) to be assembled and predetermined mapping of a wafer test on the other chip (semiconductor light receiving chip). A predetermined characteristic value C of the semiconductor device is obtained by selecting one chip and the other chip that are the optimum chip combination using the mapping information of the characteristic value B and assembling them into one device. Therefore, the productivity of semiconductor devices having predetermined characteristics can be further increased.

Therefore, in the conventional production method, there are many wastes such as non-standard products, unnecessary rank products, inventory, etc. However, by adopting the production method of the present invention, predetermined characteristics are obtained. Waste of semiconductor device production can be eliminated, fixed inventory can be eliminated, costs can be reduced, and delivery can be performed according to the schedule.

[Brief description of drawings]

FIG. 1 is a sectional view schematically showing the structure of a photocoupler.

FIG. 2 is a diagram showing a circuit configuration of a photocoupler.

FIG. 3 is a graph showing a light output distribution for each wafer in one batch of infrared light emitting diode chips.

FIG. 4 is a graph showing a light output distribution of all n wafers in one batch of infrared light emitting diodes.

FIG. 5 is a graph showing hFE distribution for each wafer in one batch of phototransistor chips.

FIG. 6 is a graph showing the hFE distribution of all n wafers in one batch of phototransistor chips.

FIG. 7 is a diagram showing a current conversion efficiency (CTR) distribution and rank classification of a photocoupler.

FIG. 8 is a graph showing a wafer median distribution of light output of an infrared light emitting diode chip.

FIG. 9 is a graph showing a wafer median distribution of hFE of a phototransistor chip.

FIG. 10 is a diagram showing wafer rank classification of infrared light emitting diode chips.

FIG. 11 is a diagram showing wafer rank classification of phototransistor chips.

FIG. 12 is a diagram showing a current conversion rate (CTR) distribution of a photocoupler produced by the production method of the present invention.

FIG. 13 is a flowchart showing an example of processing contents executed in the embodiment of the production method of the present invention.

FIG. 14 is a flowchart showing another example of the processing contents executed in the embodiment of the production method of the present invention.

FIG. 15 is an explanatory diagram of an assembly using mapping of optical output data of an infrared light emitting diode chip.

FIG. 16 is an explanatory diagram of an assembly using mapping of hFE data of a phototransistor chip.

FIG. 17 is a flowchart showing an example of processing contents executed in another embodiment of the production method of the present invention.

[Explanation of symbols]

1 Photocoupler (semiconductor device) 2 Infrared light emitting diode chip (semiconductor light emitting chip) 3 Phototransistor chip (semiconductor light receiving chip) 4,5 frames 6 translucent resin 7 Opaque resin

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Claims (9)

[Claims] 1. A production method for producing a semiconductor device by assembling two chips into one device, and using the wafer test data of one of the chips to be assembled, the chip having a predetermined characteristic value A is used for each wafer or The chips are ranked in lot units, and by using the wafer test data of the other chip, the chips are ranked in wafer units or lot units with a predetermined characteristic value B, and one chip of a specific rank and another specific rank are classified. By assembling the other chip in a wafer unit or a lot unit, a predetermined characteristic value C of the semiconductor device is obtained.
A method for producing a semiconductor device, comprising: 2. A manufacturing method for manufacturing a semiconductor device by assembling two chips into one device, wherein mapping information of a predetermined characteristic value A in a wafer test of one chip to be assembled and a wafer test of the other chip. It is possible to obtain the predetermined characteristic value C of the semiconductor device by selecting one chip and the other chip that are the optimum chip combination by using the mapping information of the predetermined characteristic value B in FIG. A method for producing a semiconductor device having a feature. 3. A semiconductor device is manufactured using a semiconductor light emitting chip as the one chip and a semiconductor light receiving chip as the other chip.
Alternatively, the method for producing a semiconductor device according to the item 2. 4. The method for producing a semiconductor device according to claim 3, wherein the semiconductor light emitting chip is a semiconductor infrared light emitting chip or a semiconductor visible light emitting chip. 5. The semiconductor light receiving chip comprises a phototransistor, a photo Darlington transistor, a photothyristor, a phototriac, a photoMOS or a photoI.
The method for producing a semiconductor device according to claim 3, wherein C is C. 6. A semiconductor device to be manufactured is a photo coupler, a photo Darlington coupler, a photo thyristor coupler, a photo triac coupler, a photo MOS coupler,
The method for producing a semiconductor device according to claim 3, wherein the method is a photo IC coupler or a photo interrupter. 7. The method for producing a semiconductor device according to claim 1, wherein the predetermined characteristic value A is a light output value. 8. The method for producing a semiconductor device according to claim 1, wherein the characteristic value B is hFE. 9. The method for producing a semiconductor device according to claim 1, wherein the predetermined characteristic value C of the semiconductor device is current conversion efficiency.