JP2674546B2 - Beam-lead type semiconductor device manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a beam lead type semiconductor device, and more particularly to a method of manufacturing a beam lead type semiconductor device which minimizes an adverse effect in an etching process when forming a semiconductor substrate.

2. Description of the Related Art Generally, in a conventional method of manufacturing a beam lead type semiconductor device of this kind, as shown in FIG.
There are two processes (A), (B), and (C). In the step (A), the semiconductor substrate portion 1 covered with the insulating film portion 30
The element unit 2 is formed on the surface of 0 with at least one of a transistor, a diode, an integrated circuit, and the like. In the step (B), in-element wiring 4 having a fine pattern made of a relatively thin metal layer is formed in the element portion 2, and in order to obtain strength, a beam lead 5 made of a metal layer having a thickness of about 10 μm or more is formed. Are formed on the insulating film portion 30. The in-element wiring 4 and the beam lead 5 are formed by dividing the same kind of metal into two or more steps, for example, a sputtering step and two plating steps. Next, the back surface of the semiconductor substrate portion 10 is polished to an appropriate thickness, for example, a thickness of about 50 μm, and the photoresist layer 8 is formed on the portion of the semiconductor substrate portion 10 corresponding to the back surface of the element portion 2.
In the step (C), the semiconductor substrate portion 10 is removed by etching according to the photoresist layer 8 while leaving the vicinity of the element portion 2. Further, the insulating film portion 30 between the beam lead 5 and the removed semiconductor substrate portion 10 and the remaining photoresist layer 8 are removed to form the semiconductor substrate 19 from the semiconductor substrate portion 10 and the insulating film. Three
Is formed and the back surface of the beam lead 5 is exposed to complete the beam lead type semiconductor device. As shown in FIG. 5, the beam lead 5 of the beam lead type semiconductor device is shown.
However, what is mechanically coupled to the element portion 2 or the semiconductor substrate 19 is a portion in contact with the semiconductor substrate 19 with the insulating film 3 interposed therebetween. As a result, as shown in FIG.
When the semiconductor substrate 19 is sufficiently larger than the range of the wiring 4 in the element portion (approximately 180 μm in the length direction of the beam lead 5), the stray capacitance increases via the semiconductor substrate 19 and the capacitance between the leads also increases. On the contrary, as shown in the semiconductor substrate 18, when the wiring is small to the extent of the wiring in the element portion 4 (approximately 170 μm in the length direction of the beam lead 5), the area of the bonding portion between the semiconductor substrate 18 and the beam lead 5 is The beam lead 5 becomes smaller and the semiconductor substrate 1
It becomes easy to peel off from 8. Further, the beam lead type semiconductor device is used for an ultra high frequency circuit of several GHz, and it is very important that the capacity is small in order to realize high performance.

The above-described conventional method for manufacturing a beam-lead type semiconductor device has the etching rate within the plane of the semiconductor substrate portion or between wafer portions when the unnecessary portion of the semiconductor substrate portion is removed by etching treatment. Variation, the degree of adhesion between the photoresist layer and the semiconductor substrate portion, the thickness of the semiconductor substrate portion, and the like change the lateral expansion of the etching region, resulting in variation in size of the semiconductor substrate after etching. As a result, when the size of the semiconductor substrate becomes smaller, there is a problem that the beam leads are easily peeled off from the semiconductor substrate. On the other hand, in order to secure sufficient mechanical strength between the semiconductor substrate and the beam lead, it is necessary to make the size approximately 1500 μm ² or more. When the contact width between the wide portion of the beam lead and the semiconductor substrate is 10 μm and the stray capacitance is about 0.09 pF, when the contact width increases by 20 μm, the stray capacitance becomes about 0.14 pF. As described above, when the semiconductor substrate becomes larger due to variations in etching, the stray capacitance becomes even larger. As a result, there is a problem in that the use of the beam-lead type semiconductor device by the conventional manufacturing method inevitably deteriorates the performance. An object of the present invention is to provide a stable method of manufacturing a beam lead type semiconductor device, which can form a contact surface between a semiconductor substrate and a beam lead substantially constant while minimizing adverse effects of the etching process.

A method of manufacturing a beam lead type semiconductor device according to the present invention comprises a first step of forming a groove crossing a beam lead formation planned region of a semiconductor substrate portion on a surface covered with an insulating film. A second step of applying a liquid insulating material to fill the groove and cover a region where a beam lead is to be formed, and a third step of forming a beam lead on the insulating material and connecting to the active area And a fourth step of forming a semiconductor substrate by selectively removing a part of the semiconductor substrate and the insulator while leaving the active region. In another method in the first step, the groove is formed at a position surrounding the active region. In addition, in the fourth step, all of the insulator is removed, and the insulator is left in a gap formed around the connection peripheral portion between the semiconductor substrate and the beam lead by the groove. Have one.

In the method of manufacturing the beam lead type semiconductor device by the above means, the groove and filling the groove with an insulating material are
The size of the semiconductor substrate is regulated, and the stray capacitance between the semiconductor substrate and the beam lead is prevented from increasing.

Next, the present invention will be described with reference to the drawings. FIG. 1 is a manufacturing process diagram showing an embodiment of the present invention.
In the method of manufacturing the beam lead type semiconductor device shown in FIG. 1, six steps (A), (B) and (F) are shown. First, as the material, the element portion 2 is
A semi-insulating material having a high resistance value of 1.0 × 10 ⁷ Ωcm or more and a size of about 100 μm × 100 μm, “GaA
s ″ and becomes an active region on the surface of the semiconductor substrate portion 10. Further, the element portion 2 has 1.0 to 5.0 ×.
A buffer layer having a concentration of 10 ¹⁸ cm ⁻³ and a thickness of 1.5 to 2.5 μm, and the surface of the buffer layer were further 1.0 to 1.5 × 1.
It is assumed that an active layer having a concentration of 0 ¹⁷ cm ⁻³ and a thickness of 0.3 to 0.5 μm is stacked, and a Schottky diode is formed using these. Also,
The semiconductor substrate 10 has a thickness of about 5 on the surface other than the element 2.
It is assumed that the insulating film portion 30 of 000 angstrom is covered. First, in the step (A), the semiconductor substrate portion 10
Outside the area where the beam lead 5 is fixed to the
A groove 6 having a size of m and a width of 20 μm is formed. In the next step (B), polyimide is filled in the groove 6 as the insulator portion 70, and spin coating is performed so that the flat portion has a thickness of 2 μm. In the next step (C), the polyimide (insulator part 70) in the element part 2 which becomes the active region and the part where the beam lead 5 is fixed to the semiconductor substrate 1 is removed. In the next step (D), as shown in FIG. 2, the element portion internal wiring 4 of the element portion 2 and the beam lead 5 having a width of approximately 120 μm are formed of two or more steps of the same metal, for example, a sputtering step, It is formed by two plating steps.
Next, in the step, in order to protect the element portion 2, the upper surface of the wafer portion is attached to a glass plate (not shown), and the back surface of the semiconductor substrate portion 10 is polished by, for example, CMP (Chemical Mechanical Polishing). Thickness is almost 50
μm, and a photoresist layer 8 is formed on the back surface portion from the active region of the element portion 2 to the vicinity of the center line of the groove 6. In the next step (E), the semiconductor substrate portion 10 is turned into the photoresist layer 8
The semiconductor substrate 1 is generated from the semiconductor substrate 10 by removing the semiconductor substrate 1 by etching according to the above method, except for the vicinity of the element 2. In the final step (F), the generated semiconductor substrate 1
The insulating film portion 30 and the insulating material portion 70 around the are removed to expose the back surface of the beam lead 5, the insulating film 3 is formed, and then peeled off from the glass plate to form a semiconductor of the beam lead type Schottky diode. The device is completed.
In this example, a gap is formed by one wall of the groove at the peripheral portion of the semiconductor substrate, and the vicinity of the beam lead of the semiconductor substrate can be excluded from the etching processing range. As a result, the area of the region where the beam lead is fixed via the insulating film can be made substantially constant, and the area can be defined to the minimum, so that the stray capacitance between the semiconductor substrate and the beam lead can be reduced to the minimum. For example, if the contact width between the wide part of the beam lead and the semiconductor substrate is 10 μm and the stray capacitance is about 0.09 pF, the stray capacitance is 0.10 pF even if the contact width is increased by 20 μm due to variations in the etching process. It can be suppressed to the value below (about 0.14 pF in the past). Further, the influence of the variation in the size of the semiconductor substrate on the characteristics due to the etching process is extremely small. Next, in the example shown in FIG. 3, subsequent to the step (E) shown in FIG. 1, the externally exposed portion of the semiconductor substrate 1 is removed from the insulator portion 70 in the groove 6 to remove the semiconductor substrate 1 and the beam lead. Insulator 7 is left in the gap around the connection with 5. This insulator 7 is the semiconductor substrate 1
Since it has a role of fixing the beam lead 5 in, the area to be bonded via the insulating film 3 other than the groove 6 for fixing the beam lead 5 can be made smaller. As a result,
The variation of the stray capacitance caused by the variation of the etching process of the semiconductor substrate 1 is smaller than the conventional value due to the thickness of the insulator 7. Next, in the case shown in FIG.
A 50 μm vertical groove 61, which is cut longitudinally with respect to the μm groove 6, is provided at a position surrounding the periphery of the element portion 2 in the active region. The groove 6 and the vertical groove 61 both have a depth of 5 μm. The vertical groove 61 can suppress the influence of variations due to the etching process in the direction perpendicular to the length direction of the beam lead 5. As a result, the stray capacitance between the semiconductor substrate and the beam lead can be made smaller than in the case where only the groove 6 shown in FIG. 2 is used. In the above description,
The air gap between the semiconductor substrate and the beam lead is determined by the groove depth of 5 μm. If the depth of this groove is too shallow, the air gap will be narrow and therefore stray capacitance between the semiconductor substrate and the beam lead cannot be minimized. On the other hand, when the depth of the groove is too deep, the filling property of the insulating material is poor and the etching process becomes difficult. The method of manufacturing the beam read type semiconductor device described above can be applied to diodes other than Schottky diodes, transistors, integrated circuits, and the like. Also, the material of the semiconductor substrate is "GaAs"
It can be applied not only to "Si", etc. In particular, when a semiconductor substrate having a low resistivity is used, the stray capacitance between the beam leads becomes large. Therefore, the above manufacturing method and the structure by this manufacturing method are effective in preventing the stray capacitance from increasing. Although polyimide is used as the insulator, the same effect can be obtained by using another liquid insulator, for example, "SOG" instead. Furthermore, since a process such as photolithography etching, which is a usual semiconductor device manufacturing technique, can be applied, the effect of the present invention is great. As described above, the materials, shapes, sizes, positions, etc. of the constituent elements are not limited by the above description as long as they fulfill the above functions.

As described above, according to the present invention, a groove that traverses a region where a beam lead is to be formed in a semiconductor substrate portion is formed on the surface covered with an insulating film, and then a liquid insulating material is applied. After filling the groove and covering the beam lead forming surface, a beam lead is formed on this insulator and connected to the active region, and a part of the semiconductor substrate portion is selectively removed leaving this active region, A process of forming a semiconductor substrate has been proposed. According to this method, the size of the active region portion of the semiconductor substrate is determined by the groove formed first,
Since there is little influence on the variation in the etching process of the semiconductor substrate, the area of the portion where the beam leads are fixed to the semiconductor substrate is fixed, and this area can be minimized to reduce the stray capacitance between the beam leads and to reduce the stray capacitance. Can also be reduced. Further, by forming the groove in a position surrounding the active region, when the semiconductor substrate is etched from the back surface, each semiconductor device can be separated by a small etching process by the depth of the groove. As a result, work time is shortened,
Lateral expansion due to etching and variation in lateral expansion can be reduced, and more stable manufacturing can be realized.

[Brief description of the drawings]

FIG. 1 is a process chart showing one embodiment of the present invention.

FIG. 2 is a plan view showing an embodiment in FIG.

FIG. 3 is a partial cross-sectional view showing another embodiment of the present invention.

FIG. 4 is a plan view showing another embodiment different from FIG.

FIG. 5 is a process chart showing a conventional example.

FIG. 6 is a plan view showing an example in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 semiconductor substrate 2 element part (active region) 3 insulating film 4 wiring in element part 5 beam lead 6 groove 7 insulator (polyimide) 8 photoresist layer 10 semiconductor substrate part 30 insulating film part 61 vertical groove 70 insulator part (polyimide)

Claims (4)

(57) [Claims] 1. A first method for forming a groove across a region for forming a beam lead of a semiconductor substrate on a surface covered with an insulating film.
A second step of applying a liquid insulating material to fill the groove and cover a region where a beam lead is to be formed, and a third step of forming a beam lead on the insulating material and connecting it to an active area. And a fourth step of selectively removing a part of the semiconductor substrate portion and the insulator while leaving the active region to form a semiconductor substrate. Manufacturing method. 2. The method of manufacturing a beam lead type semiconductor device according to claim 1, wherein the groove is formed at a position surrounding the active region in the first step. 3. The method according to claim 1, wherein in the fourth step,
A method for manufacturing a beam lead type semiconductor device, characterized in that all of said insulator is removed. 4. The method according to claim 1, wherein in the fourth step,
The method for manufacturing a beam lead type semiconductor device, wherein the portion where the insulator is left is a gap formed by the groove at a peripheral portion of the connection between the semiconductor substrate and the beam lead.