JP2006032518A - Semiconductor device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device wherein the operational characteristic of a semiconductor element can be prevented from degrading by emitting efficiently a heat generating within the semiconductor device to the outside, and to provide its manufacturing method. <P>SOLUTION: Heat dissipation electrodes are formed on the whole rear surface of a semiconductor substrate wherein semiconductor elements are formed on its front surface, and via holes penetrating the heat dissipation electrodes are formed. In such the semiconductor device, a recess is formed on the rear surface of the semiconductor substrate, and then the heat dissipation electrode is formed in the recess as well as the inside of the via hole, thereby providing a recess in the heat dissipation electrode. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a semiconductor device and a method for manufacturing the same.

  A semiconductor element constituting a semiconductor device usually generates heat when operating.

  In particular, a semiconductor element that flows a large current, such as a field effect transistor that functions as an amplifier, generates relatively large heat when operating.

  If the temperature of the semiconductor device rises due to the heat generated by this semiconductor element, the operating characteristics of the semiconductor element deteriorate, such as the amplification factor of the amplifier decreases and the mutual conductance with other semiconductor elements decreases. There was a risk.

  Therefore, conventionally, in the semiconductor device 100 shown in FIG. 7, the heat generated on the semiconductor element formation surface (hereinafter referred to as “front surface”) side of the semiconductor substrate 103 is propagated to the back surface side of the semiconductor substrate 103. A via hole 101 for electrically connecting the front surface and the back surface of the semiconductor substrate 103, and a heat radiation electrode 105 for dissipating the heat transmitted to the back surface side of the semiconductor substrate 103 through the via hole 101 to the outside. Had.

  In addition, the code | symbol 102 shown in the figure is an insulating film.

  The heat dissipation electrode 105 is a via hole formed by depositing a metal film having high thermal conductivity such as gold on the inner surface of a through hole penetrating from the back surface of the semiconductor substrate 103 to the bottom surface of the metal terminal 104 provided on the surface of the semiconductor substrate 103. When forming 101, a metal film such as gold was also deposited on the entire flat back surface of the semiconductor substrate.

In this way, by conducting heat dissipation electrode 105 and via hole 101, heat generated near the surface of semiconductor substrate 103 is dissipated from heat dissipation electrode 105 to the outside, so that the operating characteristics of the semiconductor element due to heat deteriorate. (For example, refer to Patent Document 1).
JP-A-8-78437

  However, with the recent high integration of semiconductor devices, the number of semiconductor elements formed in a unit area on a semiconductor substrate has increased rapidly, and the operation of the semiconductor device has also increased in speed. The amount of heat generated when the element operates tends to increase.

  As a result, by simply forming a metal film on the flat back surface of a semiconductor substrate as in the prior art, heat generated when a large number of semiconductor elements operate at high speed cannot be sufficiently dissipated to the outside. There was a possibility of deteriorating the characteristics of the element.

  Therefore, it has been difficult to reduce the size of the semiconductor device because the heat dissipation efficiency has to be improved by increasing the diameter of the via hole.

  Therefore, in the present invention according to claim 1, in the semiconductor device in which the heat dissipation electrode is formed on the entire back surface of the semiconductor substrate having the semiconductor element formed on the front surface, and the via hole connected to the heat dissipation electrode is formed in the semiconductor substrate, A recess was provided in the electrode, and a via hole was formed in the recess.

  In the present invention according to claim 2, a plurality of recesses are provided.

  Further, in the present invention according to claim 3, in the method of manufacturing a semiconductor device in which a heat dissipation electrode is formed on the entire back surface of the semiconductor substrate having a semiconductor element formed on the front surface, and a via hole is formed to conduct to the heat dissipation electrode. A recess is formed on the back surface of the heat sink, and then a heat radiation electrode is formed on the recess and the inner surface of the via hole.

  Further, in the present invention according to claim 4, the heat radiation electrode is formed after the plurality of recesses are formed.

  The present invention has the following effects.

  In the present invention according to claim 1, in the semiconductor device in which the heat dissipation electrode is formed on the entire back surface of the semiconductor substrate on which the semiconductor element is formed on the front surface, and the via hole connected to the heat dissipation electrode is formed on the semiconductor substrate, the heat dissipation electrode Since a recess is provided and a via hole is formed in the recess, the heat dissipation area of the heat dissipation electrode is expanded and the length of the via hole is reduced to efficiently dissipate heat generated when the semiconductor element operates to the outside. Therefore, it is possible to prevent the operating characteristics of the semiconductor element from deteriorating due to heat, and to provide a semiconductor device that is miniaturized by forming a via hole with a small diameter. .

  Further, in the present invention according to claim 2, since the plurality of recesses are provided, the heat radiation area of the heat radiation electrode can be further expanded, so that the efficiency of radiating heat generated when the semiconductor element operates is further improved. A semiconductor device can be provided.

  Further, in the present invention according to claim 3, in the method of manufacturing a semiconductor device in which a heat dissipation electrode is formed on the entire back surface of the semiconductor substrate having a semiconductor element formed on the front surface, and a via hole is formed to conduct to the heat dissipation electrode. And then forming a heat dissipation electrode on the recess and the inner surface of the via hole, the area of the heat dissipation electrode is expanded and the length of the via hole is reduced to reduce the semiconductor element. Since heat generated during operation can be efficiently dissipated to the outside, it is possible to prevent the operating characteristics of the semiconductor element from being deteriorated by heat, and to further reduce the diameter of the via hole. Thus, a semiconductor device with a reduced size can be manufactured.

  Further, in the present invention according to claim 4, since the heat radiation electrode is formed after the plurality of recesses are formed, a semiconductor device with further improved efficiency of radiating heat generated when the semiconductor element operates is manufactured. can do.

  The semiconductor device according to the present invention has a heat radiation electrode for dissipating heat generated when the semiconductor element operates to the entire back surface of the semiconductor substrate having the semiconductor element formed on the front surface.

  The heat radiation electrode is connected to a via hole that electrically connects the front surface and the back surface of the semiconductor substrate, and heat generated near the surface of the semiconductor substrate when the semiconductor element operates is transmitted through the via hole. The heat radiation electrode radiates outside.

  In particular, the heat dissipation electrode has a structure in which a metal film having high thermal conductivity is formed on the entire back surface of the semiconductor substrate in which the concave portion is formed and the inner surface of the via hole, thereby being electrically connected to the via hole.

  And it has the structure where the opening part of the via hole was formed in the recessed part provided in the back surface of the semiconductor substrate.

  As described above, the heat radiation electrode is formed on the back surface of the semiconductor substrate provided with the recesses, and thus has a structure having the recesses similar to the semiconductor substrate.

  Therefore, compared with the conventional heat radiation electrode formed on the back surface of the flat semiconductor substrate, it becomes possible to secure a wider heat radiation area, and thereby efficiently generate heat generated when the semiconductor element operates. Can be diverged.

  Furthermore, since the opening of the via hole is formed so as to be positioned in the recess provided on the back surface of the semiconductor substrate, the length of the via hole can be shortened.

  This shortens the propagation path when the heat generated on the front surface side of the semiconductor substrate is propagated to the back surface side of the semiconductor substrate, so that the heat radiation efficiency can also be improved.

  In addition, since the parasitic impedance of the via hole itself can be reduced, the reliability of the via hole can be improved.

  Furthermore, since the via hole diameter can be reduced by reducing the length of the via hole, the semiconductor device can be downsized.

  Moreover, the recessed part provided in a semiconductor substrate can further expand a thermal radiation area by providing the concave surface in multiple steps | paragraphs, and can further improve thermal radiation efficiency.

  Further, the heat radiation area of the heat radiation electrode can be expanded by changing the shape of the concave portion or increasing the number of the concave portions.

  A method for manufacturing a semiconductor device according to the present invention will be described below with reference to FIGS.

  First, as shown in FIG. 1, a predetermined semiconductor element (not shown) is formed on a semiconductor element formation surface (hereinafter referred to as “surface”) of a GaAs (gallium arsenide) substrate 1, and SiN (not shown) is used as an insulating film. A silicon nitride film 2 is formed by a CVD (Chemical Vapor Deposition) method.

  Next, after forming a resist film (not shown) on the surface of the SiN film 2, a predetermined pattern is formed on the resist film using a photolithography method, and then a predetermined position of the SiN film 2 is set to RIE ( The surface of the GaAs substrate 1 is partially exposed by selective removal using a reactive ion etching method, and then the resist film is removed.

  Subsequently, a metal film is formed so as to cover the exposed portion of the GaAs substrate 1 and the SiN film 2.

  This metal film is formed by depositing Ti (titanium), Pt (platinum), and Au (gold) at a predetermined thickness in this order by sputtering.

  Next, unnecessary portions of the metal film on the surface of the SiN film 2 are removed by ion milling, thereby forming connection terminals 3 that are in contact with the via holes 7 to be formed later in the vicinity of the surface of the GaAs substrate 1.

  Next, as shown in FIG. 2, a wax 4 is applied to the upper surfaces of the SiN film 2 and the connection terminals 3, and then a sapphire substrate 5 is attached to the upper surface of the wax 4 as a support substrate.

  Next, while supporting the GaAs substrate 1 by the sapphire substrate 5, the back surface of the GaAs substrate 1 (the surface opposite to the semiconductor element formation surface of the GaAs substrate 1) is back-ground until the GaAs substrate 1 reaches a predetermined thickness. Polish using the method.

  Next, as shown in FIG. 3, the recess 6 is formed on the lower surface of the GaAs substrate 1 by partially removing the back surface of the GaAs substrate 1.

  When forming the recess 6, a resist film is first formed on the back surface of the GaAs substrate 1, and then the resist film is subjected to predetermined patterning.

  At this time, the resist film is patterned using a photolithography method so as to mask the periphery of the formation position of a via hole 7 to be formed later.

  Next, the recess 6 is formed by etching the unmasked portion of the back surface of the GaAs substrate 1 using an aqueous solution of phosphoric acid and hydrogen peroxide.

  Next, after forming a resist film on the back surface of the GaAs substrate 1 in which the recess 6 is formed, the resist film is patterned using a photolithography method, and then a predetermined position of the recess 6 is passed with phosphoric acid and excess. By etching using an aqueous solution of hydrogen oxide, a through hole reaching the bottom surface of the connection terminal 3 is formed as shown in FIG.

  Next, a Ti thin film and an Au thin film are formed on the entire back surface of the GaAs substrate 1 including the through hole by sputtering, and then an Au film is deposited on the surface of the thin film by using a plating method. Thus, the heat radiation electrode 8 conducted to the via hole 7 is formed.

  As described above, since the heat radiation electrode 8 is formed on the entire back surface of the GaAs substrate 1 in which the recess 6 is formed, the heat radiation surface of the heat radiation electrode 8 has a structure with a step rather than a flat surface. Compared with the heat radiation electrode 105 (see FIG. 7) provided on the heat radiation area, the heat radiation area can be expanded, thereby improving the efficiency of radiating heat generated when the semiconductor element operates.

  Finally, after dissolving the wax 4, the sapphire substrate 5 is removed, and a recess 6 is formed on the back surface of the GaAs substrate 1 on which the semiconductor element is formed as shown in FIG. A semiconductor device 9 is formed in which a heat radiation electrode 8 is formed which is electrically connected to.

  Further, in the present embodiment, as shown in FIG. 5, the method of manufacturing the semiconductor device 9 in which the recess (hereinafter referred to as “first recess”) 6 is formed on the back surface of the GaAs substrate 1 has been described. In the present invention, as shown in FIG. 6, a second recess 10 that further conducts to the via hole 7 can be formed in the first recess 6.

  Then, a second recess 10 is formed in the first recess 6 to conduct to the via hole 7, and then a heat dissipation electrode 8 is formed on the entire back surface of the GaAs substrate 1, thereby expanding the heat dissipation area of the heat dissipation electrode 8. And the length of the via hole 7 can be shortened.

  As a result, it is possible to simultaneously achieve further improvement of the heat dissipation efficiency and further reduction of the parasitic impedance of the via hole.

It is explanatory drawing which shows the manufacturing process of the semiconductor device which concerns on this invention. It is explanatory drawing which shows the manufacturing process of the semiconductor device which concerns on this invention. It is explanatory drawing which shows the manufacturing process of the semiconductor device which concerns on this invention. It is explanatory drawing which shows the manufacturing process of the semiconductor device which concerns on this invention. It is explanatory drawing which shows the manufacturing process of the semiconductor device which concerns on this invention. It is explanatory drawing which shows the manufacturing process of the semiconductor device which concerns on this invention. It is sectional drawing which shows the conventional semiconductor device.

Explanation of symbols

1 GaAs substrate 2 SiN film 3 Connection terminal 4 Wax 5 Sapphire substrate 6 Recess (first recess)
7 Via hole 8 Radiation electrode 9 Semiconductor device 10 Second recess

Claims (4)

In the semiconductor device in which a heat dissipation electrode is formed on the entire back surface of the semiconductor substrate on which the semiconductor element is formed on the front surface, and a via hole is formed in the semiconductor substrate to conduct to the heat dissipation electrode.
A semiconductor device, wherein a recess is provided in the heat dissipation electrode, and the via hole is formed in the recess.   2. The semiconductor device according to claim 1, wherein a plurality of the recesses are provided. In the method of manufacturing a semiconductor device in which a heat dissipation electrode is formed on the entire back surface of a semiconductor substrate on which a semiconductor element is formed on the surface, and a via hole is formed in conduction with the heat dissipation electrode.
A method of manufacturing a semiconductor device, comprising: forming a recess on a back surface of the semiconductor substrate; and thereafter forming a heat radiation electrode on the recess and an inner surface of the via hole.   4. The method for manufacturing a semiconductor device according to claim 3, wherein the heat radiation electrode is formed after the plurality of recesses are formed.

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