JP3303639B2 - Method for producing copper-based lead material for semiconductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a copper-based lead material for semiconductors having a small internal residual stress and excellent etching workability.

[0002]

2. Description of the Related Art Lead materials for semiconductors (lead frames, etc.)
In general, a copper alloy, a 42 alloy, or the like is used.
The semiconductor lead material is, for example, after hot rolling a copper alloy ingot, repeating cold rolling and intermediate annealing, after finishing to a desired thickness by finish temper rolling after final intermediate annealing, elongation rate It is manufactured by modifying the shape by applying a tension leveler at 0.4% or more, and then processing it into a predetermined shape by pressing or etching. At the time of etching, dimples are formed in the die pad portion (locations where the semiconductor chips are bonded) to improve the bonding property of the semiconductor chips. However, in the method of correcting the shape with such a tension leveler, since the internal residual stress increases, the die pad portion warps during the etching process, and if the warpage exceeds an allowable value, the bonding property of the semiconductor chip deteriorates. However, there has been a problem that the reliability of wire bonding is significantly reduced. Therefore, a method in which a tension leveler having an elongation of 0.2% or more is applied after finish temper rolling and then low-temperature annealing or continuous annealing is applied, or a method in which a tension leveler or roller leveler is applied after low-temperature annealing or continuous annealing is proposed. (Japanese Utility Model Application Laid-Open No. 63-86851). Here, low-temperature annealing refers to batch-type low-temperature annealing, and continuous annealing refers to annealing during running.

[0003]

In recent years, as a part of miniaturization and high integration of electronic devices, lead materials for semiconductors have also become thinner, and lead materials having smaller internal residual stress have been required. Was. However, it has been difficult to stably obtain a lead material which has a good shape and satisfies the above-mentioned requirements even by the method proposed above. From these facts, the present inventors conducted research on a method of reducing internal residual stress, and found that the shape could be maintained well even when the elongation at the tension leveler was reduced. The invention has been completed. An object of the present invention is to provide a method for producing a copper-based lead material for a semiconductor having a small internal residual stress and excellent etching workability.

[0004]

According to the first aspect of the present invention,
Elongation rate of copper alloy for semiconductor lead material after finish temper rolling
Low-temperature annealing at a temperature of 200 to 500 ° C. for 5 to 300 minutes or continuous annealing at a temperature of 300 to 800 ° C. for 5 seconds to 5 minutes by applying a tension leveler at more than 0.1% and less than 0.2%. A method for producing a copper-based lead material for semiconductors.

According to a second aspect of the present invention, a copper alloy for a semiconductor lead material after finish temper rolling has an elongation of more than 0.1%.
Applying tension leveler Ku less than 0.2%, then 2
Low-temperature annealing at a temperature of 00 to 500 ° C for 5 to 300 minutes or continuous annealing at a temperature of 300 to 800 ° C for 5 seconds to 5 minutes, and then a tension leveler or a roller leveler with an elongation of less than 0.2%. A method for producing a copper-based lead material for a semiconductor, comprising:

[0006]

In the invention according to claim 1, the tension leveler is applied to the copper alloy for the semiconductor lead material after the finish temper rolling in order to correct the shape of the strip, and the elongation at that time is reduced. The reason for limiting to greater than 0.1% and less than 0.2% is that if the elongation is 0.1% or less, the shape of the strip will
When the elongation is not sufficiently corrected and the elongation is 0.2% or more, a large internal residual stress is applied by the tension leveler, and the internal residual stress is not sufficiently released in the next low-temperature annealing step. The reason why low-temperature annealing or continuous annealing is performed after the tension leveler is applied is to release internal residual stress. The reason for limiting the conditions of the low-temperature annealing to a temperature of 200 to 500 ° C. for 5 to 300 minutes is that even if the temperature is lower than 200 ° C. or less than 5 minutes, the internal residual stress is not sufficiently released and the die pad portion is warped during etching. It is because it occurs. 5
If the temperature exceeds 00 ° C., the softening of the strip becomes severe and sufficient strength cannot be obtained. On the other hand, if the time exceeds 300 minutes, the productivity is lowered and it is not practical. The reason for limiting the temperature and time in the case of continuous annealing is the same as in the case of low-temperature annealing.
In the present invention, a tension leveler, a roller leveler or the like is not applied after low-temperature annealing or continuous annealing.

In the invention according to claim 2, the reason why the tension leveler or the roller leveler is further applied to the strip (lead material) after low-temperature annealing or continuous annealing obtained in the invention according to claim 1 is that in the longitudinal direction of the strip. And to correct the warp in the width direction. The reason why the elongation percentage of the tension leveler at that time is less than 0.2% is that if the elongation percentage is 0.2% or more, the internal residual stress increases, and the warpage of the die pad portion during etching processing increases. . For correcting the warpage of the strip after the low-temperature annealing or the continuous annealing, tension is not necessarily required, and therefore, a roller leveler that does not apply tension to the strip can also be used. The leveling at this time may be performed at the stage of wide strip in the middle of the manufacturing process or at the stage of narrowing after slitting.

[0008]

The present invention will be described below in detail with reference to examples. (Example 1) Sn contained 0.25 wt% and Cr 0.30 wt%,
A copper alloy consisting of the remaining copper and unavoidable impurities is melt-cast by a conventional method to form an ingot, and the ingot is hot-rolled and then surface-cut, and then cold-rolled and annealed repeatedly.
Finish passivation rolling of 0% was performed to obtain a copper alloy strip having a thickness of 0.2 mm. Next, a tension leveler was applied to the copper alloy strip, followed by low-temperature annealing or continuous annealing to produce a copper-based lead material for a semiconductor. The elongation percentage in the tension leveler and the annealing conditions in low-temperature annealing or continuous annealing were variously changed.

With respect to each of the obtained copper-based lead materials for semiconductors, steepness, curl, internal residual stress, amount of warpage of the die pad portion, and tensile strength were examined. The steepness was expressed as a percentage of the undulation height of the plate divided by the pitch. The curl hangs a 1 meter long material on a wall and expresses it as the distance from the lower end to the wall. The internal residual stress was obtained by removing the surface of the strip by a predetermined thickness by etching, measuring the warpage at that time, obtaining the internal residual stress distribution, and expressing the distribution as the maximum tensile residual stress. The amount of warpage of the die pad part is 2
The dimple area of the material of 0 × 20 mm is
% And the dimple depth was etched at 50% of the thickness of the strip, and expressed by the difference between the height of the center of the die pad and the periphery. The manufacturing conditions are shown in Table 1 and the test results are shown in Table 2.

[0010]

[Table 1]

[0011]

[Table 2]

As is clear from Table 2, the sample of the present invention (N
o. 1 to 6) are all strip shapes (steepness, curl)
And the tensile strength is equivalent to that of the conventional product (No. 14), and the internal residual stress and the warpage of the die pad portion are the same as those of the conventional product (No. 1).
It was remarkably superior to 4). In contrast,
No. of the comparative example product 7, 8, 11 and 12 had a large elongation at the tension leveler after finish temper rolling,
No. In Nos. 9 and 13, the temperature in the low-temperature annealing or the continuous annealing was too low, so that the internal residual stress remained large, and the warpage of the die pad portion increased. No. In No. 10, required strength was not obtained because low-temperature annealing was performed at high temperature.

(Example 2) The copper-based lead material for a semiconductor after the low-temperature annealing or the continuous annealing obtained in the example 1 is further subjected to a tension leveler or a roller leveler (RL). Was manufactured. The elongation at the tension leveler was varied. With respect to each of the obtained copper-based lead materials for semiconductors, the steepness, curl, internal residual stress, amount of warpage of the die pad portion, and tensile strength were examined in the same manner as in Example 1.
The manufacturing conditions are shown in Table 3, and the test results are shown in Table 4.

[0014]

[Table 3]

[0015]

[Table 4]

As is clear from Table 4, the invention examples (Nos. 15 to 18) according to claim 2 were further subjected to a leveler or a roller leveler after annealing. (Curl) and tensile strength were better than those of the invention sample of claim 1. However, no. In Nos. 19 and 20, since the elongation percentage of the leveler after annealing was too large, the internal residual stress remained large and the warpage of the die pad portion increased.

[0017]

As described above, according to the present invention,
A copper-based lead material for a semiconductor having a small internal residual stress and excellent in etching workability can be obtained, and has an industrially remarkable effect.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-270945 (JP, A) JP-A-4-94815 (JP, A) JP-A-7-227620 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) C22F 1/00-3/02 H01L 23/48 H01L 23/50

Claims (2)

(57) [Claims] 1. A tension leveler is applied to the copper alloy for a semiconductor lead material after the finish temper rolling at an elongation of more than 0.1% and less than 0.2%, and then at a temperature of 200 to 500 ° C. for 5 to 300 minutes. Low temperature annealing or 300-800
A method for producing a copper-based lead material for a semiconductor, comprising performing continuous annealing by heating at a temperature of 5C for 5 seconds to 5 minutes. 2. A copper alloy for a semiconductor lead material after finish temper rolling is applied with a tension leveler at an elongation of more than 0.1% and less than 0.2%, and then at a temperature of 200 to 500 ° C. for 5 to 300 minutes. Low temperature annealing or 300-800
A method for producing a copper-based lead material for a semiconductor, comprising: performing continuous annealing by heating at a temperature of 5 ° C. for 5 seconds to 5 minutes; and then applying a tension leveler or a roller leveler at an elongation of less than 0.2%.