Semiconductor package

Abstract

To suppress adhesion of metal fine particles generated during welding to a semiconductor element in a semiconductor package having a vacuum package structure in which a lid material is welded to a housing and the semiconductor element is arranged in an airtight space of reduced pressure environment.SOLUTION: A semiconductor package 1 has an airtight space in a reduced-pressure state in which a lid material 9 is welded to a housing 4 having a recess 41 and the recess 41 is closed. In the recess 41, a semiconductor element 2 is arranged. The semiconductor package 1 has a gas adsorbing material 6 arranged in the airtight space so as not to abut on the semiconductor element 2. The gas adsorbing material 6 has a three-dimensional shape surrounding the semiconductor element 2 so that the semiconductor element 2 is not exposed to the lid material 9.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a semiconductor package.

Background Art

[0002] Conventionally, a vacuum package structure is known in which a semiconductor element and a gas adsorbent for maintaining the reduced-pressure atmosphere are disposed in an airtight space under a reduced-pressure atmosphere in which a housing and a lid member are joined (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The above-described vacuum package structure is applied to a fuel reformer that reforms fuel in a fuel cell system. However, instead of a fuel reformer made of a semiconductor material or the like, it is also possible to configure it as another semiconductor device by using a semiconductor sensor or the like.

[0005] As a result of intensive studies on this type of semiconductor device by the present inventors, it has been newly found that when the lid member is welded to the housing, metal fine particles are generated in the airtight space due to material boiling due to heat or the like, and the sensor characteristics may deteriorate when these adhere to the semiconductor sensor. In order to prevent such a situation, it is conceivable to provide a reduced-pressure space by MEMS in the vacuum package structure and to form a double vacuum structure in which the semiconductor sensor is disposed in the reduced-pressure space. However, when such a double vacuum structure is adopted, the semiconductor package becomes larger in size and the manufacturing cost increases. Note that MEMS is an abbreviation for Micro Electro Mechanical Systems.

[0006] In view of the above, the present disclosure aims to provide a semiconductor package having a vacuum package structure in which a lid member is welded to a housing and a semiconductor element is disposed in a depressurized airtight space, and the influence on the semiconductor element caused by the welding is reduced.

Means for Solving the Problems

[0007] According to one aspect of the present disclosure, there is provided a semiconductor package including a semiconductor element (2), a housing (4) having a recess (41) in which the semiconductor element is housed, a lid member (9) welded to the housing and closing the recess, and a gas adsorbent (6) disposed in an airtight space formed by closing the recess with the lid member so as not to contact the semiconductor element and having a three-dimensional shape surrounding the semiconductor element so that the semiconductor element is not exposed to the lid member. The airtight space is in a depressurized state.

[0008] Thus, in a semiconductor package in which a lid member is welded to a housing having a recess, and a semiconductor element is disposed in a depressurized airtight space formed by the recess and the lid member, a three-dimensional gas adsorbent surrounding the semiconductor element is disposed in the airtight space. Therefore, when the lid member is welded to the housing, the semiconductor element is not exposed to the lid member, adhesion of metal fine particles generated during the welding to the semiconductor element is suppressed, and a semiconductor package having a structure in which the influence on the semiconductor element caused by the welding is reduced is obtained.

[0009] Note that the reference numerals in parentheses attached to each component etc. indicate an example of the correspondence relationship between the component etc. and the specific components etc. described in the embodiments described later.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4A

Figure 4B

Figure 4C

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

MODE FOR CARRYING OUT THE INVENTION

[0011] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numerals and described.

[0012] (Embodiment) The semiconductor package 1 of an embodiment will be described with reference to the drawings. The semiconductor package 1 is suitably used as a semiconductor sensor such as a gyro sensor mounted on a moving body such as a vehicle, for example. Of course, it can also be applied to uses for detecting other physical quantities.

[0013] In FIGS. 2 and 3, the portion of the base material 7 that is bent among the base materials 7 constituting the gas adsorbent 6 described later is indicated by a one-dot chain line, and when the base material 7 after being bent is viewed in perspective, the portion of the outer contour of the base material 7 that is not visible is indicated by a broken line.

[0014] 〔Basic configuration〕 As shown in FIG. 1, for example, the semiconductor package 1 of this embodiment includes a semiconductor element 2, a bonding material 3, a housing 4, a wire 5, a gas adsorbent 6, and a lid material 9. The semiconductor package 1 has a lid material 9 welded to a housing 4 having a recess 41, and has a vacuum package structure in which the semiconductor element 2 is disposed in a depressurized airtight space formed by the recess 41 and the lid material 9. In the semiconductor package 1, a part of the gas adsorbent 6 is welded to the lid material 9, and the semiconductor element 2 is covered by the three-dimensional gas adsorbent 6. The semiconductor package 1 has a structure in which metal fine particles generated when the lid material 9 is welded to the housing 4 are suppressed from adhering to the semiconductor element 2 by the gas adsorbent 6.

[0015] The semiconductor element 2 is, for example, in a plate shape in which a sensor portion (not shown) is formed on a semiconductor substrate made of a semiconductor material such as silicon or silicon carbide by a known semiconductor device manufacturing process. The semiconductor element 2 is, for example, joined at its lower surface 2a to the bottom surface 41a of the recess via the bonding material 3, and the wire 5 is connected to an electrode (not shown) on the upper surface 2b. The semiconductor element 2 is, for example, an MEMS sensor that outputs a signal corresponding to a physical quantity applied from the outside such as vibration, inertial force, pressure, angular velocity, or light by a sensor portion (not shown). The semiconductor element 2 is connected to an external power source or the like via the wire 5, for example, and enables electrical communication between the sensor portion (not shown) and an external circuit or the like.

[0016] For the bonding material 3, for example, any bonding material such as solder is used.

[0017] The housing 4 is, for example, a member whose base is made of an arbitrary insulating material such as alumina and can accommodate the semiconductor element 2 and the gas adsorbent 6. The housing 4 has, for example, a recess 41 having a step portion 42 on one surface 4a and an electrode 43 for welding the lid material 9. The housing 4 has, for example, a through electrode (not shown) formed in the step portion 42 that enables electrical connection to the outside, and the through electrode and the semiconductor element 2 are connected via the wire 5. The depth, planar dimensions, shape, etc. of the recess 41 can be appropriately changed according to the outer shape, dimensions, and connection method of the semiconductor element 2.

[0018] The wire 5 is made of an arbitrary conductive material such as gold, silver, copper, or aluminum, and is connected to the semiconductor element 2 and the housing 4 by wire bonding.

[0019] The gas adsorbent 6 includes, for example, a base material 7 and a gas adsorption film 8 partially disposed on both the front and back surfaces of the base material 7. The gas adsorbent 6 suppresses the adhesion of metal fine particles generated when the lid material 9 is welded to the housing 4 to the semiconductor element 2, adsorbs the gas in the airtight space in which the semiconductor element 2 is housed, and plays a role in maintaining the degree of vacuum in the reduced-pressure environment. The gas adsorbent 6 is, for example, a member welded and integrated with the central portion of the lid material 9 at one location, and is arranged so as not to contact the semiconductor element 2.

[0020] The base material 7 is, for example, a plate material made of an arbitrary high heat-resistant material that can be welded to the lid material 9 and can withstand the heating temperature (for example, 300°C to 400°C, etc.) when activating the gas adsorption film 8, and is formed into a three-dimensional shape by a method such as bending. The base material 7 is made of, for example, a metal material such as stainless steel, iron, nickel, or cobalt, or an alloy material. The base material 7 has, for example, a top plate portion 71 disposed on the upper surface 2b of the semiconductor element 2 opposite to the lower surface 2a facing the bottom surface 41a of the recess of the housing 4, and a side plate portion 72 extending from the top plate portion 71 toward the bottom surface 41a of the recess.

[0021] The base material 7 has, for example, an outer dimension adjusted to the inner dimension of the recess 41 so that the lid material 9 can be positioned with respect to the housing 4 when the lid material 9 is welded to the housing 4. For example, the base material 7 is dimensioned taking into account the dimensional tolerance when assembling the gas adsorbent 6, the lid material 9, and the housing 4, and the shrinkage difference with the housing 4 at the heating temperature when activating the gas adsorption film 8, such that the distance between the side plate portion 72 and the side surface 41b of the recess is a predetermined value or less throughout.

[0022] For example, a case will be described where the dimensions of the concave portion 41 in the planar direction are a substantially square shape with a length and width of 10 mm, and the base of the housing 4 is made of alumina and the base material 7 is made of SUS304. In this case, for example, when the dimensional tolerance in the planar direction is about 100 μm and the heating temperature is 350°C, the expansion and contraction difference between the housing 4 and the base material 7 is about 30 μm. At this time, for the base material 7, for example, by designing the outer dimensions of the opposing side plate portions 72 to be 9.8 mm, the distance between the side plate portion 72 and the concave side surface 41b becomes about 200 μm, which is larger than about 130 μm obtained by combining the dimensional tolerance and the expansion and contraction difference. Thereby, the base material 7 functions as a positioning jig when the side plate portion 72 assembles the lid material 9 to the housing 4, and the interference with the concave side surface 41b due to thermal expansion is suppressed. Note that the portion of the side plate portion 72 located on the step portion 42 has a smaller dimension along the depth direction of the concave portion 41 than the portion of the side plate portion 72 facing the concave bottom surface 41a. Note that the depth direction of the concave portion 41 is, for example, a direction along the normal direction with respect to the concave bottom surface 41a, and can also be said to be the thickness direction of the housing 4.

[0023] The base material 7 is made of, for example, stainless steel as shown in FIG. 2. A plate material with a thickness of about 0.2 mm is prepared. After cutting and removing the four corners of the plate material, bending is performed at a position with a predetermined width smaller than the depth of the concave portion 41 from the four-sided outer contour to form it. For example, when the dimension in the depth direction of the concave side surface 41b is 9 mm, the plate material may be bent at a position 8.9 mm from the end so that the side plate portion 72 becomes 8.9 mm. Further, as shown in FIG. 3, for example, the base material 7 may have a shape having an overlapping portion 721 where a part of the side plate portion 72 overlaps with another part of the side plate portion 72 as long as it does not contact the concave side surface 41b. In the latter case, in the base material 7, the gaps at the four corners between the side plate portions 72 disappear, and the adhesion of metal fine particles due to the welding of the lid material 9 and the housing 4 to the semiconductor element 2 is further suppressed.

[0024] The base material 7 preferably has its dimensions adjusted such that, for example, with the portion of the side plate portion 72 facing the concave bottom surface 41a or the stepped portion 42 as the end surface, part or all of the end surface abuts against the concave bottom surface 41a or the stepped portion 42. This is because when the end surface of the side plate portion 72 of the base material 7 abuts against the concave bottom surface 41a or the stepped portion 42, when welding the lid material 9 to the housing 4, the lid material 9 can be supported and deformation such that the lid material 9 is recessed toward the concave bottom surface 41a side can be suppressed. However, the base material 7 only needs to be shaped such that the semiconductor element 2 and the lid material 9 do not directly face each other, that is, it only needs to shield the semiconductor element 2 and the lid material 9, and the end surface of the side plate portion 72 does not necessarily abut against the concave bottom surface 41a and the stepped portion 42.

[0025] The gas adsorption film 8 is disposed, for example, in the airtight space in which the semiconductor element 2 is housed, adsorbs a gas that reduces the degree of vacuum in the reduced-pressure environment, and maintains the degree of vacuum in the airtight space. Examples of the gas adsorbed by the gas adsorption film 8 include hydrogen gas, oxygen gas, nitrogen gas, moisture, hydrocarbon gas, or a mixed gas thereof. The gas adsorption film 8 is composed of, for example, an alloy material mainly composed of zirconium and containing titanium, vanadium, or cobalt, and can also be referred to as a getter material. The gas adsorption film 8 is formed, for example, by sintering metal powder made of the above-described alloy material on the plate material before processing the base material 7, and covers the portion of the plate material excluding the planned welding position and the planned bending position with the lid material 9. The gas adsorption film 8 is brought into an activated state in which it adsorbs gas, for example, by performing heat treatment at a temperature equal to or higher than a predetermined temperature after welding the lid material 9 integrated with the gas adsorbent 6 and the housing 4 in a reduced-pressure environment.

[0026] The gas adsorption film 8 is disposed, for example, on the front and back surfaces of the base material 7 and on the inner surface of the lid material 9. The gas adsorption film 8 is disposed, for example, on portions other than a predetermined region such as a range with a diameter of 2 mm centered on the welding portion with the lid material 9 in the base material 7. Further, the gas adsorption film 8 is disposed, for example, on portions other than a predetermined region such as a range with a diameter of 2 mm centered on the welding portion with the base material 7 on the inner surface of the lid material 9. Thereby, it is possible to suppress the gas adsorption film 8 from being oxidized by the heat during welding of the lid material 9 and the base material 7, resulting in a decrease in gas adsorption capacity, and the degree of vacuum in the hermetic space from decreasing due to gas release from the gas adsorption film 8 accompanying oxidation.

[0027] The gas adsorption film 8 is disposed, for example, at a portion different from the bent portion 73 by using the boundary between the top plate portion 71 and the side plate portion 72 as the bent portion 73. Thereby, it is possible to suppress cracks from occurring in the gas adsorption film 8 due to the bending process of the base material 7, and thus the gas adsorption film 8 from peeling off from the base material 7 and adhering to the semiconductor element 2.

[0028] The lid material 9 is, for example, weldable to the housing 4 and the base material 7, and is made of any high heat-resistant material that can withstand the heating temperature when activating the gas adsorption film 8, similar to the base material 7. The lid material 9 is formed, for example, with plating films (not shown) made of gold-tin, nickel, etc. on both sides of a substrate made of an alloy material such as Kovar, and has a thickness of about 0.1 mm. The lid material 9 is joined to the base material 7 of the gas adsorbent 6 at one location in the central portion 91, with a predetermined region centered on the point located above the center of the bottom surface 41a of the concave portion in a top view when assembled to the housing 4 being defined as the central portion 91. The lid material 9 is joined to the gas adsorbent 6 in advance, for example, by bringing the center of the top plate portion 71 of the gas adsorbent 6 into contact with the center of the central portion 91 and using any method such as laser welding using laser light or resistance welding by energization.

[0029] Note that the lid member 9 may be joined to the gas adsorbent 6 with a sintered type joining material such as sintered silver, sintered gold, or sintered copper. When the lid member 9 is joined to the gas adsorbent 6 using a low-temperature sintered type joining material that can be joined at a temperature of 150°C or lower at which the gas adsorption film 8 is less likely to deteriorate, for example, the gas adsorption film 8 may be formed up to the vicinity of the central portion 91 on the inner surface on the housing 4 side.

[0030] The above is the basic configuration of the semiconductor package 1.

[0031] 〔Method for manufacturing semiconductor package〕 The semiconductor package 1 is manufactured, for example, through the following steps.

[0032] First, as shown in, for example, FIG. 4A, a gas adsorbent 6 and a lid member 9 having a gas adsorption film 8 formed thereon are prepared. At this time, the gas adsorption films 8 of both members are in a state before being activated. Subsequently, as shown in, for example, FIG. 4B, while bringing the gas adsorbent 6 and the lid member 9 into contact with each other in an aligned state using a jig (not shown), laser light is irradiated to weld the center of the lid member 9 and the center of the top plate portion 71 of the gas adsorbent 6 at one point.

[0033] Also, as shown in, for example, FIG. 4C, the semiconductor element 2 is joined to the bottom surface 41a of the recess of the housing 4, wire bonding is performed between the semiconductor element 2 and the housing 4, and they are connected by a wire 5. Then, after housing the gas adsorbent 6 in the recess 41 of the housing 4 with the lid member 9 integrated with the gas adsorbent 6 and covering the semiconductor element 2 with the gas adsorbent 6, the outer peripheral portion of the lid member 9 is welded to the housing 4.

[0034] For example, 1×10 -3In a reduced-pressure environment of less than Pa, after the gas adsorbent 6 is stored in the recess 41 of the housing 4, while applying a current of 140 A to the electrode 43, the outer peripheral portions of the housing 4 and the lid member 9 are welded by seam welding or the like in which the portion in contact with the electrode 43 is pressed by a roller (not shown). At this time, for example, after welding both longitudinal ends of the outer peripheral portion of the lid member 9 to the housing 4, both lateral ends of the outer peripheral portion are welded to the housing 4, so that there is no gap between the housing 4 and the lid member 9, and the semiconductor element 2 is enclosed in the airtight space of the reduced-pressure environment.

[0035] Finally, for example, the semiconductor package 1 is placed in a heating furnace (not shown) and heat-treated by heating at 350 °C for 30 minutes to activate the gas adsorbent 6 and the gas adsorption film 8 of the lid member 9. Thereby, gas adsorption in the airtight space is started in the semiconductor package 1.

[0036] 〔Effect of gas adsorbent〕 Next, the effect of the three-dimensionally shaped gas adsorbent 6 will be described in comparison with the semiconductor package 100 of the comparative example shown in FIG. 5.

[0037] The semiconductor package 100 of the comparative example includes, for example, as shown in FIG. 5, a semiconductor element 2, bonding materials 3, 120, a housing 4, wires 5, a gas adsorbent 110, and a lid member 9. The semiconductor package 100 differs from the semiconductor package 1 of the present embodiment in the shape of the gas adsorbent 110 and the bonding configuration between the gas adsorbent 110 and the lid member 9. The gas adsorbent 110 has, for example, a flat plate shape and is disposed on the semiconductor element 2. The gas adsorbent 110 is bonded to the lid member 9 via the bonding material 120 in the vicinity of both ends of the outer peripheral portion.

[0038] Although the gas adsorbent 110 is disposed on the semiconductor element 2 in the semiconductor package 100, the gas adsorbent 110 does not shield between the semiconductor element 2 and the lid member 9. For this reason, in the semiconductor package 100, the fumes generated when welding the housing 4 and the lid member 9, that is, metal fine particles stay in the hermetic space, and a part of them adheres to the semiconductor element 2. When metal fine particles adhere to the semiconductor element 2, the characteristics of a sensor portion (not shown) of the semiconductor element 2 deteriorate. For example, when the semiconductor element 2 is a sensor element that senses the frequency and amplitude of a vibrator (not shown), the vibration frequency and resonance point of the vibrator shift or the amplitude fluctuates due to the adhesion of the metal fine particles, resulting in a deterioration of the sensor characteristics.

[0039] On the other hand, in the semiconductor package 1 of the present embodiment, the gas adsorbent 6 has a three-dimensional shape that covers the semiconductor element 2, and the space between the semiconductor element 2 and the lid member 9 is shielded by the gas adsorbent 6. For this reason, in the semiconductor package 1, the fumes generated when welding the lid member 9 to the housing 4 adhere to the gas adsorbent 6, the semiconductor element 2 is protected by the gas adsorbent 6, and a decrease in the sensor characteristics of a sensor portion (not shown) of the semiconductor element 2 is suppressed.

[0040] For example, when the semiconductor packages 1 and 100 are configured as gyro sensors, the resonance frequency of the vibrator of the semiconductor element 2 is designed to be 10 kHz, and the deviation amount from the designed value of the resonance frequency when measuring the resonance frequency is compared with N = 10, the results shown in FIG. 6 were obtained. The example shown in FIG. 6 is the semiconductor package 1 of the present embodiment, and the comparative example is the semiconductor package 100.

[0041] In the comparative example, the deviation amount from the designed value of the resonance frequency had an average value of approximately -1 Hz, a maximum value of approximately +7 Hz, and a minimum value of approximately -6 Hz. On the other hand, in the example, the deviation amount from the designed value of the resonance frequency had an average value of approximately +1 Hz, a maximum value of approximately +3 Hz, and a minimum value of approximately -2 Hz, and the variation range was smaller than that of the comparative example. This result suggests that in the example, the adhesion of metal fine particles generated by welding to the semiconductor element 2 was suppressed, and thus the variation in sensor characteristics was suppressed. The measurement of the resonance frequency can be performed, for example, using a laser Doppler vibrometer.

[0042] Also, for the semiconductor packages 1 and 100, when the planar size of the recess 41 was designed to be 10 mm square, the deviation amount from the bonding center when the lid member 9 was welded to the housing 4 was compared with N = 10, and the results shown in FIG. 7 were obtained.

[0043] The "bonding center" referred to here is, for example, the position of the center of the frame outlined by the electrode 43 when the housing 4 is viewed from above. The "deviation amount from the bonding center" refers to the amount of positional deviation between the bonding center after welding the lid member 9 to the housing 4 and the center of the lid member 9, and is zero when the positions of the bonding center and the center of the lid member 9 coincide in a top view.

[0044] In the comparative example, the deviation amount from the bonding center had an average value of approximately 170 μm, a maximum value of approximately 330 μm, and a minimum value of approximately 40 μm. On the other hand, in the example, the deviation amount from the bonding center had an average value of approximately 50 μm, a maximum value of approximately 90 μm, and a minimum value of approximately 20 μm, and both the average value and the variation range were smaller than those of the comparative example. This result indicates that in the semiconductor package 1 of the example in which the side plate portion 72 of the gas adsorbent 6 has a distance from the side surface 41b of the recess of a predetermined value or less over the entire area, the positional deviation of the lid member 9 during welding to the housing 4 can be suppressed. The deviation amount from the bonding center can be obtained, for example, by imaging the semiconductor packages 1 and 100 from the lid member 9 side, reading the position of the bonding center and the center position of the lid member 9 by a known image analysis technique, and calculating the distance between them.

[0045] Also, regarding the semiconductor packages 1 and 100, when the degree of vacuum in the hermetic space immediately after welding the housing 4 and the lid member 9 was compared at N = 5, as shown in FIG. 8, in the comparative example, it was about 0.2 Pa, whereas in the example, it was about 0.02 Pa. This result is considered to be due to the fact that in the example, the gas adsorbent 6 has a three-dimensional shape bent so as to have the top plate portion 71 and the side plate portion 72, and is joined at one point in the center of the lid member 9 and the top plate portion 71. Specifically, in the example, for the gas adsorbent 6, more gas adsorption films 8 can be arranged by the amount of the side plate portion 72, and for the lid member 9, more gas adsorption films 8 can be arranged by the amount that the joining portion with the gas adsorbent 6 is reduced by one point compared to the comparative example. For this reason, it is considered that in the example, the gas adsorption performance is improved more than that of the comparative example by the increased amount of the gas adsorption film 8, and the degree of vacuum can be maintained higher than that of the comparative example.

[0046] Further, since the gas adsorbent 6 and the lid member 9 of the semiconductor package 1 are joined only at one central point, there is no influence of the expansion and contraction difference caused by the difference in the linear expansion coefficient between the base material 7 and the lid member 9, and the reliability against temperature change is improved compared to the semiconductor package 100.

[0047] Specifically, for example, when the base materials of the gas adsorbent 110 and the base material 7 of the gas adsorbent 6 are made of SUS304 and the base material of the lid material 9 is made of Kovar, the difference in the linear expansion coefficients between the gas adsorbents 6 and 110 and the lid material 9 is about 12 ppm / °C. In this case, when the distance between the joining portions of the gas adsorbent 110 and the lid material 9 of the semiconductor package 100 is 8 mm, the difference in expansion and contraction between the two members due to the difference in the linear expansion coefficient is about 34 μm at a heating temperature of 350°C and about 10 μm in an environment of 100°C. At this time, the gas adsorbent 110 and the lid material 9 joined at two locations are deformed and distorted in an attempt to reduce this difference in expansion and contraction. Therefore, when the temperature change occurs repeatedly, stress is repeatedly generated at the joining portion, and a shearing force is applied to the joining portion, which may cause breakage. For this reason, in the semiconductor package 100, due to long-term use, the gas adsorbent 110 may detach from the lid material 9, and there is a risk that the unfixed gas adsorbent 110 is included in the vacuum package. Further, for example, when the semiconductor element 2 has a capacitance-type sensor portion, if the gas adsorbent 110 is distorted due to the difference in the linear expansion coefficient from the lid material 9 and the distance between the semiconductor element 2 and the lid material 9 fluctuates, the change in the charge capacitance affects the capacitance of the entire element, and there is a risk that the sensor characteristics fluctuate.

[0048] On the other hand, in the semiconductor package 1, since the gas adsorbent 6 and the lid material 9 are joined at one location in the central portion where thermal deformation is least likely to occur, the gas adsorbent 6 does not deform due to the difference in the linear expansion coefficient. For this reason, in the semiconductor package 1, detachment of the gas adsorbent 6 and changes in the distance from the semiconductor element 2 as described above are suppressed, and the long-term reliability against temperature changes is improved. Further, since it is not necessary to consider the difference in the linear expansion coefficient between the base material 7 of the gas adsorbent 6 and the lid material 9, the degree of freedom in selecting the materials for the base material 7 and the lid material 9 is improved, and an effect of reducing the manufacturing cost can also be obtained.

[0049] According to the present embodiment, the gas adsorbent 6 is joined to the lid material 9 at one location in the center, the gas adsorbent 6 has a three-dimensional shape surrounding the semiconductor element 2, and the semiconductor package 1 has a vacuum package structure in which the semiconductor element 2 and the lid material 9 are shielded by the gas adsorbent 6. Thereby, metal fine particles generated when the lid material 9 is welded to the housing 4 are blocked by the gas adsorbent 6, and an effect of suppressing adhesion to the semiconductor element 2 is obtained.

[0050] (1) When the semiconductor package 1 is configured such that the gas adsorbent 6 has a top plate portion 71 and a side plate portion 72, and the entire side plate portion 72 is at a distance of a predetermined value or less from the concave side surface 41b, the gas adsorbent 6 functions as a positioning jig, and displacement due to welding between the housing 4 and the lid member 9 is suppressed.

[0051] (2) When the semiconductor package 1 is configured such that part or all of the end surface of the side plate portion 72 of the gas adsorbent 6 abuts on the concave bottom surface 41a or the stepped portion 42, the gas adsorbent 6 also functions as a support portion for supporting the lid member 9. In this case, when the housing 4 and the lid member 9 are welded, the gas adsorbent 6 is suppressed from being deformed so as to be recessed toward the concave portion 41 side of the lid member 9, and an effect of reducing the amount of deformation of the lid member 9 can be obtained.

[0052] (3) When a part of the side plate portion 72 of the gas adsorbent 6 is a overlapping portion 721 that overlaps with the other part of the side plate portion 72 in the semiconductor package 1, the gap between the side plate portions 72 disappears, and the structure has a higher effect of suppressing the adhesion of metal fine particles to the semiconductor element 2.

[0053] (4) When the semiconductor package 1 is configured such that the center of the top plate portion 71 of the gas adsorbent 6 and the central portion of the lid member 9 are joined at one point, the strain caused by the difference in the linear expansion coefficient between the gas adsorbent 6 and the lid member 9 disappears, the detachment of the gas adsorbent 6 is suppressed, and the reliability is improved. Further, with such a joining structure, the gas adsorption film 8 can be disposed over a wider range of the inner surface of the lid member 9, and the effect of maintaining the degree of vacuum in the hermetic space is enhanced. Furthermore, it is not necessary to consider the difference in the linear expansion coefficient between the base material 7 and the lid member 9, and the degree of freedom in material selection of the base material 7 and the lid member 9 is increased, resulting in a package structure with reduced manufacturing costs.

[0054] (5) The semiconductor package 1 has a gas adsorption film 8 disposed on portions of the gas adsorbent 6 other than the bent portion 73 of the base material 7. This suppresses the occurrence of cracks in the gas adsorption film 8 and detachment from the base material 7 during processing of the gas adsorbent 6. Therefore, in the semiconductor package 1, it is suppressed that a part of the gas adsorption film 8 detaches and adheres to the semiconductor element 2, and the reliability is improved.

[0055] (6) The semiconductor package 1 has the gas adsorption film 8 disposed on both the front and back surfaces of the base material 7 of the gas adsorbent 6, so that the area of the gas adsorption film 8 becomes larger and the effect of maintaining the degree of vacuum in the hermetic space is enhanced. Further, the gas adsorption film 8 is disposed on the gas adsorbent 6 other than the central portion 91 which is the joint portion with the lid member 9. This suppresses the deterioration of the gas adsorption film 8 during welding of the base material 7 and the lid member 9, and enhances the effect of maintaining the degree of vacuum in the hermetic space.

[0056] (Other embodiments) Although the present disclosure has been described based on examples, it is understood that the present disclosure is not limited to such examples and structures. The present disclosure also includes various modifications and modifications within an equivalent range. In addition, various combinations and forms, and further other combinations and forms including only one of those elements, more, or less, fall within the scope and spirit of the present disclosure.

[0057] For example, as shown in FIG. 9, in the semiconductor package 1, the central portion 91 of the lid member 9 may be a recess for facilitating welding with the gas adsorbent 6. Further, when the semiconductor element 2 is joined to the bottom surface 41a of the recess of the housing 4 by flip chip bonding, the semiconductor package 1 may be configured such that the recess 41 does not have a stepped portion 42. In this case, the wire 5 is not required for the semiconductor package 1. Further, the semiconductor package 1 may have any configuration as long as the airtight space formed by the recess 41 and the lid member 9 can maintain a reduced pressure state, and a through hole for communicating a sensor portion (not shown) with the external space may be formed in a portion of the housing 4 covered by the semiconductor element 2. As described above, the semiconductor package 1 may be appropriately modified in the shape and structure of some of the components according to the type of device to which it is applied, the bonding method between the semiconductor element 2 and the housing 4, and the like.

[0058] In addition, in each of the above embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential, except in cases where it is explicitly stated that they are particularly essential and in cases where they are considered to be clearly essential in principle. Further, in each of the above embodiments, when numerical values such as the number, numerical value, amount, range, etc. of the components of the embodiment are mentioned, they are not limited to the specific number, except in cases where it is explicitly stated that they are particularly essential and in cases where they are clearly limited to a specific number in principle. Further, in each of the above embodiments, when referring to the shape, positional relationship, etc. of the components, etc., they are not limited to the specific shape, positional relationship, etc., except in cases where it is explicitly stated and in cases where they are clearly limited to a specific shape, positional relationship, etc. in principle.

Description of Reference Numerals

[0059] 2... semiconductor element, 2a... connection surface (lower surface), 2b... one surface (upper surface), 4... housing, 41... recess, 41a... bottom surface of recess, 41b... side surface of recess, 6... gas adsorbent, 7... base material, 71... top plate portion, 72... side plate portion, 73... bent portion, 8... gas adsorption film, 9... lid member, 91... central portion

Claims

1. 1. A semiconductor package comprising: A semiconductor element (2); A housing (4) having a recess (41) in which the semiconductor element is housed; A cover (9) welded to the housing and closing the recess; a gas adsorbent (6) that is disposed in an airtight space formed by closing the recess with the lid so as not to come into contact with the semiconductor element and has a three-dimensional shape surrounding the semiconductor element so as not to expose the semiconductor element relative to the lid, The airtight space of the semiconductor package is in a reduced pressure state.

2. The gas adsorbent has a three-dimensionally shaped substrate (7) and a gas adsorption film (8) formed on a surface of the substrate, The base material has a top surface (2b) that is a surface of the semiconductor element opposite to a lower surface (2a) that faces a bottom surface (41a) of the recess, a top plate portion (71) located on the top surface, and a side plate portion (72) bent from an end portion of the top plate portion and extending along a thickness direction of the housing, 2. The semiconductor package according to claim 1, wherein the side plate portion is spaced apart from a side surface of the recess by a predetermined distance over the entire area.

3. The semiconductor package according to claim 2 , wherein at least a portion of the side plate portion abuts against a bottom surface (41 a) of the recessed portion.

4. The semiconductor package according to claim 2 , wherein the side plate portion has an overlapping portion (721) that is partially folded and overlaps another portion of the side plate portion.

5. The gas adsorbent has a three-dimensionally shaped substrate (7) and a gas adsorption film (8) formed on a surface of the substrate, The base material has a top surface (2b) that is a surface of the semiconductor element opposite to a lower surface (2a) that faces a bottom surface (41a) of the recess, a top plate portion (71) located on the top surface, and a side plate portion (72) bent from an end portion of the top plate portion and extending along a thickness direction of the housing, 2. The semiconductor package according to claim 1, wherein a portion of the lid located at the center of the recess is defined as a central portion (91), and the lid is welded to the top plate portion at the central portion.

6. 6. The semiconductor package according to claim 5, wherein the boundary between the top plate portion and the side plate portion of the base material is a bent portion (73), and the gas adsorption film is formed at a position of the base material different from the bent portion.

7. The semiconductor package according to claim 5 , wherein the gas adsorption film is formed on both the front and back surfaces of the base material.

8. The semiconductor package according to claim 5 , wherein the gas adsorption film is formed on a portion of the base material other than a bonding portion with the lid material.

9. 9. The semiconductor package according to claim 1, wherein the semiconductor element is a plate-shaped sensor element for detecting vibration.

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