Patent Publication Number: US-2017358538-A1

Title: Semiconductor device and method for manufacturing the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The disclosure of Japanese Patent Application No. 2016-114504 filed on Jun. 8, 2016 including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
     BACKGROUND 
     The present invention relates to a semiconductor device and a method for manufacturing the same. 
     Japanese Unexamined Patent Application Publication No. 2014-154661 (Patent Document 1) discloses a marking structure where a plurality of dots are formed in a surface of a semiconductor wafer etc. In the marking structure described in Patent Document  1 , visibility of the marking structure is improved by optimizing a depth of each dot. 
     [Patent Document]
     [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2014-154661   

     SUMMARY 
     According to the marking structure described in Patent Document 1, the shape of each dot is uniform. Therefore, when a depth of the dot is too shallow, marking will fade. On the other hand, when the depth of the dot is too deep, marking bodies such as a semiconductor wafer etc. will scatter, generating particles. 
     Other objects and novel features will be apparent from the following description taken in conjunction with the accompanying drawings. 
     A semiconductor device according to one embodiment has a marking structure. The marking structure includes a body for marking having a surface, a first mark group having a first concave portion formed in the surface, and a second mark group having a second concave portion formed adjacent to the first concave portion in the surface. The first concave portion and the second concave portion differ in shape so that they may cause light reflection differently. 
     According to the semiconductor device of one embodiment, it becomes possible to improve visibility of the marking structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are top views of marking structure according to Embodiment 1; 
         FIG. 2  is a cross-sectional view of the marking structure according to Embodiment 1; 
         FIG. 3  is a process flowchart in a marking method according to Embodiment 1; 
         FIG. 4  is a cross-sectional view of the marking structure in a first concave portion forming step; 
         FIG. 5  is a cross-sectional view of the marking structure in a second concave portion forming step; 
         FIG. 6  is a cross-sectional view of the marking structure according a comparative example; 
         FIGS. 7A and 7B  are schematic diagrams showing a state of reflection when light is applied to the marking structure according to Embodiment 1 and the marking structure according to the comparative example; 
         FIG. 8  is a cross-sectional view of the marking structure according to Embodiment 2; 
         FIG. 9  is a process flowchart in a marking method according to Embodiment 2; 
         FIG. 10  is a cross-sectional view of the marking structure in a concave portion forming step; 
         FIGS. 11A and 11B  are cross-sectional views of the marking structure in a surface roughening step; 
         FIG. 12  is a schematic diagram showing a state of reflection when light is applied to the marking structure according to Embodiment 2; 
         FIGS. 13A and 13B  are cross-sectional views of the marking structure according to Embodiment 3; 
         FIG. 14  is a top view of the marking structure according to Embodiment 3; 
         FIGS. 15A and 15B  are cross-sectional views of the marking structure in the first concave portion forming step; 
         FIGS. 16A and 16B  are cross-sectional views of the marking structure in the second concave portion forming step; 
         FIG. 17  is a schematic diagram showing a state of reflection when light is applied to the marking structure according to Embodiment 3; and 
         FIGS. 18A and 18B  are cross-sectional views of the marking structure according to Embodiment 4. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, embodiments will be explained with reference to drawings. Further, like reference characters designate the same or similar parts throughout the drawings. Also, at least some parts of the embodiments described below may be combined as required. 
     Embodiment 1 
     Now, the configuration of a semiconductor device according to Embodiment 1 will be explained. Further, in the semiconductor device, a wafer in which semiconductor elements, such as a transistor, are formed shall also be included. 
     As shown in  FIG. 1A , the semiconductor device according to Embodiment 1 has a marking structure MA. The marking structure MA includes a body for marking MB. The body for marking MB is a semiconductor wafer W in the semiconductor device according to Embodiment 1. The semiconductor wafer W has a surface S. 
     As shown in  FIG. 1B , the marking structure MA has a first mark group including a first concave portion CP 1  and a second mark group including a second concave portion CP 2 . The first concave portion CP 1  is formed over the surface S of the semiconductor wafer W. The second concave portion CP 2  is formed over the surface S of the semiconductor wafer W. The first concave portion CP 1  and the second concave portion CP 2  are formed being adjacent to each other. Further, the first concave portion CP 1  and the second concave portion CP 2  should just be adjacent to each other at least in one direction. 
     The first concave portion CP 1  and the second concave portion CP 2  are so arranged as to draw characters such as an alphabet, a numeric, etc. For example, in  FIG. 1B , a numeric  5  is drawn by the first concave portion CP 1  and the second concave portion CP 2 . In this way, the first concave portion CP 1  and the second concave portion CP 2  show information. The information is, for example, a lot number of the semiconductor wafer W, a wafer number of the semiconductor wafer W, etc. 
     As shown in  FIG. 2 , the first concave portion CP 1  and the second concave portion CP differ in shape so that they may cause light reflection differently. More specifically, the first concave portion CP 1  has a first depth D 1 . The first depth D 1  is a distance from the surface S of the semiconductor wafer W to a bottom of the first concave portion CP 1 . The second concave portion CP 2  has a second depth D 2 . The second depth D 2  is a distance from the surface S of the semiconductor wafer W to a bottom of the second concave portion CP 2 . The first depth D 1  is different from the second depth D 2 . For example, the first depth D 1  is deeper than the second depth D 2 . As a result, the first concave portion CP 1  and the second concave portion CP 2  are different in shape. 
     Hereafter, a method for manufacturing a semiconductor device according to Embodiment 1 will be explained. As shown in  FIG. 3 , the method for manufacturing a semiconductor device according to Embodiment 1 includes a concave portion forming step S 1 . The concave portion forming step S 1  includes a first concave portion forming step Sll and a second concave portion forming step S 12 . The first concave portion CP  1  is formed in the first concave portion forming step S 11 . The concave portion CP 2  is formed in the second concave portion forming step S 12 . 
     As shown in  FIG. 4 , in the first concave portion forming step S 11 , laser L is applied to the surface S of the semiconductor wafer W. As a result, the first concave portion CP 1  is formed. The laser L is, for example, a YAG (Yttrium Aluminum Garnet) laser. In the first concave portion forming step S 11 , the laser L is applied to the surface S of the semiconductor wafer W with a first intensity PW 1 . In the first concave portion forming step S 11 , by allowing the laser L to scan, the first concave portions CP 1  are formed. 
     As shown in  FIG. 5 , in the second concave portion formation step S 12 , laser L is applied to the surface S of the semiconductor wafer W. As a result, the second concave portion CP 2  is formed. In the second concave portion formation step S 12 , the laser L is applied to the surface S of the semiconductor wafer W with a second intensity PW 2  at a position adjacent to where the first concave portion CP 1  is formed. Thus, the second concave portion CP 2  and the first concave portion CP 1  are formed being adjacent to each other. In the second concave portion forming step S 12 , by allowing the laser L to scan, the second concave portions CP 2  are formed. 
     The second intensity PW 2  differs from the first intensity PW 1 . For example, the second intensity PW 2  is smaller than the first intensity PW 1 . Therefore, the second depth D 2  of the second concave portion CP 2  becomes shallower than the first depth D 1  of the first concave portion CP 1 . Thus, by changing the intensity of the laser L, it becomes possible to allow the second depth D 2  of the second concave portion cP 2  to be different from the first depth D 1  of the first concave portion CP 1 . 
     Hereinafter, in comparison with a comparative example, effects of the semiconductor device according to Embodiment  1  will be explained. 
     As shown in  FIG. 6 , a marking structure MA according to the comparative example has a semiconductor wafer W, a first concave portion CP 1 , and a second concave portion CP 2 . The semiconductor wafer W has a surface S. The first concave portion CP 1  and the second concave portion CP 2  are formed in the surface S of the semiconductor wafer W. The first concave portion CP 1  and the second concave portion CP 2  are arranged being adjacent to each other. In those respects, the marking structure of the semiconductor device according to Embodiment  1  and the marking structure according to the comparative example are the same. 
     However, the first concave portion CP 1  and the second concave portion CP 2  have the same shape. More specifically, the first concave portion CP 1  and the second concave portion CP 2  have the same depth D. In this respect, the marking structure of the semiconductor device according to Embodiment  1  and the marking structure according to the comparative example are different. 
     As shown in  FIG. 7A , in the marking structure according to the comparative example, incident light IL 1  and incident light IL 2  are reflected in the first concave portion CP 1  and the second concave portion CP 2 , respectively. As described above, the first concave portion CP 1  and the second concave portion CP 2  have the same shape (the same depth). Consequently, there occurs no variation in intensity between the reflected light RL 1  from the first concave portion CP 1  and the reflected light RL 2  from the second concave portion CP 2 . That is, a contract is less likely to be presented between the reflected light RL 1  from the first concave portion CP 1  and the reflected light RL 2  from the second concave portion CP 2 . As a result, in the marking structure according to the comparative example, visibility of the marking is low. 
     As shown in  FIG. 7B , also in the marking structure MA of the semiconductor device according Embodiment 1, incident light IL 1  and incident light IL 2  are reflected in the first concave portion CP 1  and the second concave portion CP 2 , respectively. As described above, the first concave portion CP 1  and the second concave portion CP 2  are different in shape (different in depth). Therefore, for example, because of reflected light RL 2  from the second concave portion CP 2  being interrupted by a side part etc. of the second concave portion CP 2 , intensity of the reflected light RL and intensity of the reflected light RL 2  come to be different. That is, a contrast is presented between the reflected light RL 1  from the first concave portion CP 1  and the reflected light RL 2  from the second concave portion CP 2 . 
     Therefore, according to the marking structure of the semiconductor device of Embodiment 1, visibility of the marking can be improved. 
     Hereafter, effects of a method for manufacturing a semiconductor device according to Embodiment 1 will be explained. According to the method for manufacturing a semiconductor device of Embodiment 1, the visibility of the marking can be secured even when the first concave portion CP 1  and the second concave portion CP 2  are not deeply formed. 
     Therefore, in the method for manufacturing a semiconductor device according to Embodiment 1, when the first concave portion CP 1  and the second concave portion CP 2  are formed with use of laser L, it becomes possible to suppress generation of particles in the marking process. 
     Moreover, in the method for manufacturing a semiconductor device according to Embodiment 1, when the first concave portion CP 1  is formed by applying laser L with a first intensity PW 1  and the second concave portion CP 2  is formed by applying laser L with a second intensity PW 2  which is different from the first intensity PW 1 , it becomes possible to obtain, with ease, the marking structure whose visibility is improved. 
     Embodiment 2 
     Hereinafter, the configuration of a semiconductor device according to Embodiment 2 will be explained. In this regard, points which are different from those of Embodiment 1 will be mainly explained. 
     As shown in  FIG. 8 , like the marking structure MA of Embodiment 1, a marking structure MA of the semiconductor device according to Embodiment 2 has a semiconductor wafer W as a body for marking MB, a first mark group including a first concave portion CP 1 , and a second mark group including a second concave portion CP 2 . As in the marking structure MA according to Embodiment 1, in the marking structure MA of the semiconductor device according to Embodiment 2, the first concave portion CP 1  and the second concave portion CP 2  are different in shape. 
     According to Embodiment 2, a bottom of the first concave portion CP 1  has a first surface roughness SR 1 . The first surface roughness SR 1  is an average surface roughness at the bottom of the first concave portion CP 1 . Also, a bottom of the second concave portion CP 2  has a second surface roughness SR 2 . The surface roughness SR 2  is an average surface roughness at the bottom of the second concave portion CP 2 . In addition, the average surface roughness is measured in accordance with a method specified in a contact type roughness measuring or a non-contact type roughness measuring. The first surface roughness SR 1  is greater than the second surface roughness SR 2 . 
     That is, the first concave portion CP  1  is so configured as to scatter incident light more than the second concave portion CP 2 . 
     Hereafter, a method for manufacturing a semiconductor device according to Embodiment 2 will be explained. As shown in  FIG. 9 , the method for manufacturing a semiconductor device according to Embodiment 2 includes a concave portion forming step S 1  and a surface roughening step S 2 . The concave portion forming step S 1  has a first concave portion forming step S 11  and a second concave portion forming step S 12 . 
     As shown in  FIG. 10 , in the first concave portion forming step S 11 , the first concave portion CP 1  is formed, for example, by using laser L. In the second concave portion forming step S 12 , the second concave portion CP 2  is formed, for example, by using laser L. In addition, a first intensity PW 1  of the laser L and a second intensity PW 2  of the laser L may be the same or may be different. 
     The surface roughening step S 2  includes a mask forming step S 21  and an etching step S 22 . In the mask forming step S 21 , as shown in  FIG. 11A , a mask M is formed over the surface S of the semiconductor wafer W and a bottom of the second concave portion CP 2 . In other words, the mask M is not formed over the bottom of the first concave portion CP 1 . 
     The mask M includes, for example, a photosensitive organic material, such as a photo-resist. The mask M is formed, for example, by applying a photo-resist etc. over the surface S of the semiconductor wafer W and, then, by performing patterning through photolithography etc. 
     In the etching step S 22 , as shown in  FIG. 11B , etching is applied to the bottom of the first concave portion CP 1 . Since the mask M is formed over the bottom of the second concave portion CP 2  as described above, the etching is not applied to the bottom of the second concave portion CP 2 . Therefore, as a result of the etching step S 22 , a first surface roughness SR  1  becomes greater than a second surface roughness SR 2 . In addition, the above etching is performed either by wet etching or by dry etching. 
     Hereinafter, effects of the marking structure of the semiconductor device according to Embodiment 2 will be explained. The first surface roughness SR 1  is greater than the second surface roughness SR 2 . Therefore, as shown in  FIG. 12 , incident light IL 1  having entered the first concave portion CP 1  is scattered in the bottom of the first concave portion CP 1 . As a result, the intensity of reflected light RL 1  from the first concave portion CP 1  becomes weakened. 
     On the other hand, the second surface roughness SR 2  is smaller than the first surface roughness SR 1 . Therefore, incident light IL 2  having entered the second concave portion CP 2  is reflected normally, without being scattered. As a result, the intensity of reflected light RL 2  from the second concave portion CP 2  does not become weakened. 
     Consequently, there is presented a contrast of light and darkness between the first concave portion CP 1  and the second concave portion CP 2 . Therefore, according to the marking structure of the semiconductor device of Embodiment 2, the visibility can be improved. 
     Hereinafter, effects of the method for manufacturing the semiconductor device according to Embodiment 2 will be explained. According to the marking method of Embodiment 2, it becomes possible to obtain the marking structure according to Embodiment 2. Therefore, according to the marking method of Embodiment 2, it becomes possible to provide the marking structure which improves the visibility. 
     Embodiment 3 
     Hereinafter, the configuration of a marking structure of a semiconductor device according to Embodiment 3 will be explained. In this regard, the points which are different from those in Embodiment 1 will be mainly explained. 
     As shown in  FIG. 13A , like the marking structure of the semiconductor device according to Embodiment 1, the marking structure of the semiconductor device according to Embodiment 3 includes a semiconductor wafer W as a body for marking, a first concave portion CP 1 , and a second concave portion CP 2 . Also, as in the marking structure of the semiconductor device according to Embodiment 1, in the marking structure of the semiconductor device according to Embodiment 2, the first concave portion CP 1  and the second concave portion CP 2  are different in shape. 
     Specifically, an angle which a side part of the first concave portion CP 1  forms with respect to the surface S of the semiconductor wafer W differs from an angle which a side part of the second concave portion CP 2  forms with respect to the surface S of the semiconductor wafer W. Moreover, an angle which a bottom of the first concave portion CP 1  forms with respect to the surface S of the semiconductor wafer W differs from an angle which a bottom of the second concave portion CP 2  forms with respect to the surface S of the semiconductor wafer W. 
     In addition, as shown in  FIG. 13B , the angle which the side part of first concave portion CP 1  forms with respect to the surface S of the semiconductor wafer W may be the same as the angle which the side part of the second concave portion CP 2  forms with respect to the surface S of the semiconductor wafer W. In short, the first concave portion CP 1  should just be configured as to reflect incident light in a direction different from one in which the second concave portion CP 2  does. 
     As shown in  FIG. 14 , over the surface S of the semiconductor wafer W, the plural first concave portions CP 1  are formed. The first concave portions CP 1  are so arranged as to express an alphabet, a numeric, etc. (in  FIG. 14 , they are so arranged as to express an alphabet B). Further, over the surface S of the semiconductor wafer W, the plural second concave portions CP 2  are formed. The second concave portions CP 2  are so arranged as to express an alphabet, a numeric, etc. (in  FIG. 14 , they are so arranged as to express an alphabet C). 
     The alphabet, the numeric, etc. expressed by the first concave portions CP 1  are part of first text information. The alphabet, the numeric, etc. expressed by the second concave portions CP 2  are part of second text information. The first text information and the second text information are different from each other. For example, when the first text information is a lot number of the semiconductor wafer W, the second text information is a wafer number of the semiconductor wafer W. 
     Hereafter, a method for manufacturing a semiconductor device according to Embodiment 3 will be explained. Like the method for manufacturing a semiconductor device according to Embodiment 1, the method for manufacturing a semiconductor device according to Embodiment 3 includes a concave portion forming step S 1 . Also, as in the marking method according to Embodiment 1, the concave portion forming step S 1  includes a first concave portion forming step S 11  and a second concave portion forming step S 12 . 
     As shown in  FIGS. 15A and 15B , in the first concave portion forming step S 11 , laser L is applied to the surface S of the semiconductor wafer W. The laser L is applied in an inclined manner at a first angle θ 1  with respect to the surface S of the semiconductor wafer W. Accordingly, the first concave portion CP 1  is formed. In the first concave portion forming step S 11 , by scanning the laser L, the plural first concave portions CP 1  are formed. 
     Further, as shown in  FIG. 15A , by providing an irradiation port of the laser L in an inclined manner with respect to the surface S of the semiconductor wafer W, the laser may be applied in an inclined manner at the first angle θ 1  with respect to the surface S of the semiconductor wafer W. Alternatively, as shown in  FIG. 15B , by providing the surface S of the semiconductor wafer W in an inclined manner with respect to the laser L, the laser L may be applied in an inclined manner at the first angle θ 1  with respect to the surface S of the semiconductor wafer W. 
     As shown in  FIGS. 16A and 16B , in the second concave portion forming step S 12 , laser L is applied to the surface S of the semiconductor wafer W. The laser is applied in an inclined manner at a second angle θ 2  with respect to the surface S of the semiconductor wafer W. The second angle θ 2  is different from the first angle θ 1 . Thus, the second concave portion CP 2  is formed. In the second concave portion forming step S 12 , by allowing the laser L to scan, the plural second concave portions CP 2  are formed. 
     Hereinafter, effects of the semiconductor device according to Embodiment 3 will be explained. In the semiconductor device according to Embodiment 2, an angle which a bottom of the first concave portion CP 1  forms with respect to the surface S of the semiconductor wafer W is different from an angle which a bottom of the second concave portion CP 2  forms with respect to the surface S of the semiconductor wafer W. Therefore, as shown in  FIG. 17 , the incident light IL 1  entering the first concave portion cP 1  and the incident light IL 2  entering the second concave portion cP 2  are reflected in different directions. As a result, a contrast of light and darkness is presented between the first concave portion CP 1  and the second concave portion CP 2 . Therefore, according to the semiconductor device of Embodiment 3, visibility of the marking can be improved. 
     To put it differently, the first concave portion CP 1  alone is visible from one angle and the second concave portion CP 2  alone is visible from another angle. Therefore, it becomes possible for the first concave portion CP 1  to display first text information and for the second concave portion CP 2  to display second text information being different from the first text information. As a result, it becomes possible to mark a lot of information in a small marking area. 
     Hereinafter, effects of a method for manufacturing a semiconductor device according to Embodiment 3 will be explained. According to a marking method of Embodiment 3, it becomes possible to manufacture the semiconductor device having a marking structure whose visibility is improved. Moreover, according to the method of manufacturing a semiconductor device of Embodiment 3, it becomes possible to mark a lot of information in a small marking area. 
     Embodiment 4 
     Hereafter, a semiconductor device according to Embodiment 4 will be explained. In this regard, points which are different from those of the semiconductor device according to Embodiments 1 to 3 will be mainly explained. 
     As shown in  FIGS. 18A and 18B , like the semiconductor device according to Embodiments 1 to 3, a marking structure MA of the semiconductor device according to Embodiment 4 has a body for marking MB, a first concave portion CP 1 , and a second concave portion CP 2 . Moreover, as in the marking structure MA of the semiconductor device according to Embodiments 1 to 3, in the marking structure MA of the semiconductor device according to Embodiment 4, the first concave portion CP 1  and the second concave portion CP 2  are different in shape so that they may cause light reflection differently. 
     In the marking structure of the semiconductor device according to Embodiment 4, for example, as in the marking structure of the semiconductor device according to Embodiment 1, a depth D 1  of the first concave portion CP 1  and a depth D 2  of the second concave portion CP 2  are different. 
     In the marking structure MA of the semiconductor device according to Embodiment 4, as in the marking structure MA of the semiconductor device according to Embodiment 2, surface roughness of the bottom of the first concave portion CP 1  and surface roughness of the bottom of the second concave portion CP 2  may be different. 
     In the marking structure MA of the semiconductor device according to Embodiment 4, as in the marking structure MA of the semiconductor device according to Embodiment 3, the first concave portion CP 1  maybe so configured as to reflect incident light in a direction different from one in which the second concave portion CP 2  does. 
     However, the marking structure MA of the semiconductor device according to Embodiment 4 is different from the marking structure of the semiconductor device according to Embodiments 1 to 3 in that the body for marking MB is a sealing member EM or a semiconductor substrate SUB. 
     The sealing member EM is, for example, an epoxy resin or the like. As shown in  FIG. 18A , the sealing member EM is a part of a semiconductor package PKG as a semiconductor device. The sealing member EM has a first surface FS and a second surface SS. The second surface SS is a surface of a side facing a printed circuit board or the like over which the semiconductor package PKG is mounted. The first surface FS is a surface on the opposite side of the second surface SS. The first surface FS corresponds to the surface S. A semiconductor device SD is arranged inside the sealing member EM. Moreover, a lead frame LF, for example, is provided inside the sealing member EM. The semiconductor device SD is mounted, for example, over the lead frame LF. In the lead frame LF, a terminal is projected from the sealing member EM. 
     As shown in  FIG. 18B , a semiconductor substrate SUB has a first surface FS and a second surface SS. The semiconductor substrate SUB is a part of the semiconductor device SD. The second surface SS is a surface on the opposite side of the first surface FS. The second surface SS corresponds to the surface S of the body for marking MB. Semiconductor elements, such as a transistor (not shown), are formed on the side of the first surface FS of the semiconductor substrate SUB. Moreover, over the first surface FS of the semiconductor substrate SUB, for example, there are formed an interlayer insulating film ILD, wiring WL, a protective film PV, an electrode EL, and solder balls SB. 
     Further, a method for manufacturing a semiconductor device according to Embodiment 4 is similar to the method for manufacturing a semiconductor device according to embodiments 1 to 3. 
     Hereafter, there will be explained a semiconductor device according to Embodiment 4 and effects of the method for manufacturing a semiconductor device according to Embodiment 4. According to the semiconductor device and the method for manufacturing the semiconductor device of Embodiment 4, when the body for marking MB is a sealing member EM of a semiconductor package PKG, even in the case of the semiconductor substrate SUB of the semiconductor device SD, a marking structure with high visibility can be obtained. 
     So far, embodiments of the present invention made by the inventors have been specifically explained. However, it is to be understood that the invention is not limited to the specific embodiments described above, and many widely different embodiments of the invention can be made without departing from the spirit and scope thereof.