Patent Document

FIELD OF THE INVENTION 
     The present invention relates to a process via mismatch detecting device, and more particularly relates to a process via mismatch detecting device for detecting the misalignment of vias between various metal lines in a semiconductor process. 
     BACKGROUND OF THE INVENTION 
     With the progress of semiconductor process technologies, the size of device is smaller and continuously reduced even to a sub-micro size or deep sub-micro size. Meanwhile, the size of IC is also decreased, so that the density of IC is increased continuously. 
     However, when the density of IC is rapidly increased, the multilevel interconnection process is needed in order to meet the increasing demand of interconnection after the minimization of transistors due to no sufficient area for making interconnections on the surface of a semiconductor substrate. Therefore, the design using two or more metal layers has gradually become a necessary method adopted by many IC fabrications. Furthermore, especially for the products with complicated functions, such as microprocessors and application chips, the design even with five or more metal layers has to be utilized to complete the connections among the devices inside the product. 
     In order to isolate each metal line, an insulator has to be placed between each of the metal layers. This insulator is generally called an intermetal dielectric (IMD) or interlevel dielectric (ILD). Please referring to FIG. 1, FIG. 1 is a cross-sectional diagram showing a conventional multilevel interconnection structure of IC, wherein a chip  10  has a transistor layer  80  and three metal layers. As shown in FIG. 1, the intermetal dielectric  50  is utilized between a metal layer  20  and a metal layer  30  and between the metal layer  30  and a metal layer  40 , so as to isolate the metal layers with each other thereby avoiding short circuits. Moreover, by utilizing photolithography, vias  60  are defined at appropriate positions on the dielectric layer, and then plugs  70  are formed in the vias  60  with conductive material, such as tungsten, so that the current can flow freely among the metal layer  20 , the metal layer  30  and the metal layer  40  through the plugs  70 . By utilizing the design of multilevel interconnection, the transistors can be mutually interconnected so as to form a complete circuit on the chip  10 . 
     In the earlier stage, since the IC design does not use many metal layers (mostly uses two or three metal layers), and the critical dimension thereof is broader, the metallization process of multilevel interconnection is relatively easily to be performed. However, while the multilevel interconnection is processed on a design with four metal layers, the surface of deposition layer is not smooth but rough, so that it is not easy to make the deposition layers aligned with each other. Particularly, when the vias interconnecting each of the metal layers are misaligned, the electrical properties of devices will be seriously affected, thus decreasing the reliability of product. 
     SUMMARY OF THE INVENTION 
     In view of the background of the invention described above, with the rapidly increasing density of IC, multi-metal layers are widely utilized in the multilevel interconnection process for the devices on a chip. However, because multiple deposition layers are not easy to be mutually aligned, and moreover, the electrical property of device is seriously affected especially when the vias interconnecting each of the metal layers are misaligned, thus, decreasing the product reliability. 
     It is the principal object of the present invention to provide a process via mismatch detecting device, and more particularly relates to a process via mismatch detecting device for detecting the misalignment of vias between various metal lines in a semiconductor process. While the vias between metal layers of chips are mismatched, according to the present invention, the vias on the detecting circuits of process via mismatch detecting device are mismatched as well. Therefore, by placing the vias of detecting circuits on proper locations, metal lines in various metal layers of detecting circuits will be short circuited by mismatched vias, and a voltage higher than the previous voltage before short-circuiting is generated and is regarded as a detected result of process via mismatch detecting device. Consequently, it is accurate and efficient to detect whether the vias between metal layers of chip are mismatched or not, and to detect the quantity and direction of the mismatch thereof, thereby appropriately adjusting and optimizing the process. 
     In accordance with the aforementioned purpose of the present invention, the present invention provides a process via mismatch detecting device comprising: a detecting circuit that comprises a first metal layer and a second metal layer, and the first metal layer comprises a first metal line and a second metal line, wherein the distance between the first metal line of the first metal layer and the second metal line of the first metal layer is a metal-line distance value, and one terminal of the first metal line of the first metal layer and one terminal of the second metal line of the first metal layer are electrically connected to a power source, and the second metal layer comprises a first metal line, a second metal line and a third metal line, wherein one terminal of the first metal line of the second metal layer is electrically connected to one terminal of a first resistor, and another terminal of the first resistor is electrically connected to a ground, and one terminal of the second metal line of the second metal layer is electrically connected to one terminal of a second resistor, and another terminal of the second resistor is electrically connected to the ground, and one terminal of the third metal line of the second metal layer is electrically connected to one terminal of a third resistor, and another terminal of the third resistor is electrically connected to the ground, and the first metal layer is located above the second metal layer and is placed orthogonally to the second metal layer, a dielectric layer located between the first metal layer and the second metal layer, wherein according to a predetermined via placement method, a first via is formed at a first predetermined location of the dielectric layer corresponding to the first metal line of the second metal layer, and a second via is formed at a second predetermined location of the dielectric layer corresponding to the second metal line of the second metal layer, and a third via is formed at a third predetermined location of the dielectric layer corresponding to the third metal line of the second metal layer; and a register having a first input terminal, a second input terminal, a third input terminal and an output terminal, wherein the first input terminal is electrically connected to another terminal of the first metal line of the second metal layer, and the second input terminal is electrically connected to another terminal of the second metal line of the second metal layer, and the third input terminal is electrically connected to another terminal of the third metal line of the second metal layer, and the output terminal outputs a detected result of the process via mismatch detecting device. 
     By utilizing the process via mismatch detecting device of the present invention, in order to accurately and efficiently detect the direction and quantity of mismatched via between metal layers in a chip, the vias of process via mismatch detecting device can be placed properly according to the quantity of metal layers in the chip and the required sensitivity of detecting via mismatch, so that proper adjustment can be made so as to increase the yield and to decrease the cost. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a cross-sectional diagram showing a conventional multilevel interconnection structure of IC. 
     FIG. 2 is a cross-sectional diagram showing an embodiment of the present invention applied on a chip. 
     FIG. 3 is a top perspective view showing an embodiment of the present invention. 
     FIG. 4 is a top perspective view showing another embodiment of the present invention. 
     FIG. 5 is a cross-sectional diagram showing the process via mismatch detecting device of the present invention applied on a chip having three metal layers. 
     FIG. 6 is a diagram showing the connecting relationship among the components in a preferred embodiment of the present invention according to FIG.  5 . 
     FIG. 7 is a top perspective view showing a preferred embodiment of the present invention according to FIG.  5 . 
     FIG. 8 is a top perspective view showing a preferred embodiment of the present invention according to FIG.  5 . 
     FIG. 9 is a top perspective view showing another embodiment of the present invention used for detecting the via mismatch in y direction while being applied on a chip having two metal layers. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Please referring to FIG. 2, FIG. 2 is a cross-sectional diagram showing an embodiment of the present invention applied on a chip, wherein a chip  150  has a transistor layer  115  and two metal layers (i.e. a metal layer  105  and a metal layer  110 ), wherein a plurality of dielectric layers  125  cover the metal layer  105  and the metal layer  110  for insulation, and an IC is located on the first region  140  of the chip  150 . As shown in FIG. 2, the process via mismatch detecting device of the present invention is located on the second region  145  of the chip  150 . In the process via mismatch detecting device of the present invention, the quantity of the metal layers, and the quantity of the metal lines in each metal layer, etc., are determined in accordance with the quantity of the metal layers in the chip and the required detecting sensitivity. Since the chip  150  has two metal layers structure, the process via mismatch detecting device in the second region  145  has two metal layers also. 
     Please referring to FIG.  2  and FIG. 3, FIG. 3 is a top perspective view showing an embodiment of the present invention. In FIG. 3, when the process via mismatch detecting device  170  of the present invention is applied on a chip having two metal layers, the process via mismatch detecting device  170  is composed of two metal layers (i.e. a metal layer  105  and a metal layer  110 ) and a register  175 , wherein a dielectric layer (not shown) is formed between the metal layer  105  and the metal layer  110  for insulation. 
     In order to describe the operation theorem of process via mismatch detecting device  170  concisely, let the metal layer  110  shown in FIG. 3 merely have three metal lines (a metal line  190 , a metal line  195  and a metal line  200 ), and moreover, the metal layer  105  be placed orthogonally to the metal layer  110 , so that a rectangular region  205 , on where several vias to be formed in the subsequent steps are located, is obtained and composed of the metal lines  180  and  185  located on the metal layer  105  and the metal lines  190  and  195  located on the metal layer  110 . On the other hand, as shown in FIG. 3, the metal lines  180  and  185  located on the metal layer  105  are electrically connected to a power source  215  respectively. A terminal of the metal line  190  on the metal layer  110  is electrically connected to a resistor  220  that is electrically connected to ground  240 , and another terminal of the metal line  190  is electrically connected to a register  175  through a buffer module  225 . Similarly, a terminal of the metal line  195  on the metal layer  110  is electrically connected to a resistor  220  that is electrically connected to ground  240 , and another terminal of the metal line  195  is electrically connected to a register  175  through a buffer module  225 , and a terminal of the metal line  200  on the metal layer  110  is electrically connected to a resistor  220  that is electrically connected to ground  240 , and another terminal of the metal line  200  is electrically connected to a register  175  through a buffer module  225 . 
     While the vias between metal layers in the first region  140  of the chip  150  are formed, if the locations of vias are shifted, then the metal layers are not electrically conducted through vias, or, though the metal layers are electrically conducted through mismatched vias, yet the contact resistance therebetween is increased thus decreasing the current, so that the operation of device is affected. 
     Hence, in the process via mismatch detecting device  170  of the present invention, according to the required sensitivity of detecting via mismatch, the mismatch range of via and the size of via, etc., the vias are placed within the rectangle region  205  of the dielectric layer between the metal layer  105  and the metal layer  110 . When the vias in the chip  150  shown in FIG. 2 are not mismatched, the vias  245 ,  250  and  255  located on the process via mismatch detecting device are not mismatched either, so that the metal lines  180  and  185  of the metal layer  105  are not electrically conducted to the metal lines  190  or  195  or  200  of the metal layer  110  through any one of the vias  245 ,  250  and  255 . Therefore, the metal line  190 , the metal line  195  and the metal line  200  still keep at low potentials, which are recorded in the register  175 , so that it can be known that the vias of the chip  150  are not mismatched by checking the output of register  175 . 
     When the vias of the chip  150  are mismatched, the vias  245 ,  250  and  255  located on the process via mismatch detecting device  170  are mismatched as well, so that the metal line  180  or the metal line  185  is electrically conducted to the metal line  190  or the metal line  195  or the metal line  200  through the mismatched vias  245 ,  250  and  255 . Since the metal line  180  and the metal line  185  are electrically connected to a power source  215 , the potential of the metal line  190  or that of the metal line  195  or that of the metal line  200  is increased after the metal line  190  or the metal line  195  or the metal line  200  is short-circuited with the metal line  180  or the metal line  185 , wherein the register  175  records the potentials of the metal line  190 , the metal line  195  and the metal line  200 . Therefore, it can be known that the potential of metal line  190  or that of the metal line  195  or that of the metal line  200  is increased by checking the output of register  175 , wherein the potential increase infers that the vias on the chip  150  have deviated towards the metal line  180  or the metal line  185 . The following example is used for describing the via placement principle of the process via mismatch detecting device  170  as shown in FIG.  3  and the related operation theorem. 
     For example, when implementing the process via mismatch detecting device  170  shown in FIG. 3, if the required detecting range of detecting via mismatch range is about 0.28 μm, and the required sensitivity of detecting via mismatch is about 0.14 μm (herein the required sensitivity of detecting via mismatch indicates the smallest mismatch value of via by utilizing the process via mismatch detecting device  170  shown in FIG.  3 ), and the size of each via is about 0.28 μm. First, according to the size  210  of via  245  (i.e. about 0.28 μm) and the required detecting range of detecting via mismatch range (i.e. about 0.28 μm), the metal line distance  230  between the metal line  180  and the metal line  185  is known and is about 0.84 μm; then according to the size  210  of via  245  and the required detecting range of detecting via mismatch range, the required detecting range of detecting via mismatch range is regarded as a corresponding distance  280 , and the via  245  is placed in the dielectric layer corresponding to the metal line  200 , so that both the corresponding distance  280  between the via  245  and the metal line  180  and the corresponding distance  280  between the via  245  and the metal line  185  are about 0.28 μm; then the required sensitivity of detecting via mismatch is regarded as the corresponding distance  285 , the via  250  is placed in the dielectric layer corresponding to the metal line  190 , so that the corresponding distance  285  between the via  250  and the metal line  180  is about 0.14 μm, and the distance between the via  250  and the metal line  185  is about 0.42 μm; finally, the required sensitivity of detecting via mismatch is regarded as the corresponding distance  290 , the via  255  is placed in the dielectric layer corresponding to the metal line  195 , so that the corresponding distance  290  between the via  255  and the metal line  185  is about 0.14 μm, and the distance between the via  255  and the metal line  180  is about 0.42 μm. 
     By the aforementioned via placement method, if the vias between the metal layer  105  and the metal layer  110  in the chip  150  are mismatched, the vias  245 ,  250  and  255  in the process via mismatch detecting device  170  are mismatched meanwhile. 
     If the mismatched distance of vias between the metal layer  105  and the metal layer  110  of chip  150  is between 0.14 μm and 0.28 μm (larger than the required sensitivity of detecting via mismatch) along the negative x direction, the mismatched distance of the vias  245 ,  250  and  255  on the process via mismatch detecting device is also between 0.14 μm and 0.28 μm. Since the corresponding distance  285  between the via  250  and the metal line  180  is about 0.14 μm, the metal line  180  can be short-circuited with the metal line  190  through the mismatched via  250 . Because the metal line  180  is electrically connected to the power source  215 , the potential of the metal line  190  is increased after being short-circuited with the metal line  180 . However, the potentials of the metal line  195  and the metal line  200  still stay low because the metal line  180  and the metal line  185  are not electrically conducted with the metal line  195  or the metal tine  200  through the mismatched via  245 , or the mismatched via  250 , or the mismatched via  255 . Therefore, the register  175  records that the input terminal  265  has a high potential, and the input terminal  260  and the input terminal  270  have a low potential, so that, through the result outputted from the output terminal  275  of the register  175 , the personals can recognize that the mismatched distance of vias on the chip  150  is between 0.14 μm and 0.28 μm along the negative x direction. 
     Similarly, if the mismatched distance of vias between the metal layer  105  and the metal layer  110  on the chip  150  is between 0.14 μm and 0.28 μm along the positive x direction, the mismatched distance of vias  245 ,  250  and  255  on the process via mismatch detecting device  170  is also between 0.14 μm and 0.28 μm along the positive x direction. Since the corresponding distance  290  between the via  255  and the metal line  185  is about 0.14 μm, the metal line  185  are electrically conducted with the metal line  195  through the mismatched via  255 . Because the metal line  185  is electrically connected to the power source  215 , the potential of the metal line  195  is increased after being short-circuited with the metal line  185 . However, the potentials of the metal line  190  and  200  still stay low because the metal line  185  and the metal line  180  are not electrically conducted with the metal line  190  or the metal line  200  through the mismatched via  245 , or the mismatched  250 , or the mismatched via  255 . Therefore, the register  175  records that the input terminal  270  has a high potential, and the input terminal  260  and the input terminal  265  have a low potential, so that, through the result outputted from the output terminal  275  of the register  175 , the personals can recognize that the mismatched distance of vias on the chip  150  is between 0.14 μm and 0.28 μm along the positive x direction. 
     If the mismatched distance of vias between the metal layer  105  and the metal layer  110  on the chip  150  is larger than 0.28 μm along the positive x direction or the negative x direction, the mismatched distance of vias  245 ,  250  and  255  on the process via mismatch detecting device  170  is also larger than 0.28 μm along the positive x direction or the negative x direction. Since the corresponding distance  285  between the via  250  and the metal line  180  is about 0.14 μm and the corresponding distance  290  between the via  255  and the metal line  185  is about 0.14 μm, the vias are shifted towards either positive x direction or negative x direction, so that the metal line  180  can be electrically conducted with the metal line  190  through the mismatched via  250  and with the metal line  200  through the mismatched via  245  (if the vias are shifted towards negative x direction), or the metal line  185  can be electrically conducted with the metal line  200  through the mismatched via  245  and with the metal line  195  through the mismatched via  255  (if the vias are shifted towards positive x direction). 
     Because the metal line  180  and the metal line  185  are electrically connected to the power source  215 , if the vias are shifted towards negative x direction, the potentials of the metal lines  190  and  200  are increased but the potentials of the metal line  195  still stay low. The register  175  records that the input terminals  265  and  260  have a high potential, but the input terminal  270  has a low potential, and the result is outputted from the output terminal  275  of the register  175 . If the vias are shifted towards positive x direction, the potentials of the metal lines  200  and  195  are increased but the potentials of the metal line  190  still stay low. The register  175  records that the input terminals,  260  and  270  have a high potential, but the input terminal  265  has a low potential, and the result is outputted from the output terminal  275  of the register  175 . Therefore, the personals can recognize that the mismatched distance and mismatched direction of vias on the chip  150 . 
     On the other hand, if the mismatched distance of the vias on the chip are less than 0.14 μm along the negative x direction or the positive x direction, the vias  245 ,  250  and  255  of process via mismatch detecting device are mismatched as well. However, since the distance between the via  250  and the metal line  180  is about 0.14 μm correspondingly, and the distance between the via  255  and the metal line  185  is about 0.14 μm correspondingly as well, so that the metal line  180  can not be electrically conducted with the metal line  190 , or the metal line  195 , or the metal line  200  through the vias  245 ,  250  and  255 , and similarly, the metal line  185  can not be electrically conducted with the metal line  190 , or the metal line  195 , or the metal line  200  through the vias  245 ,  250  and  255 . Thus, The register  175  records that the input terminals  260 ,  265  and  270  have a low potential. Hence, the personals can not recognize that the mismatched state, such as mismatched distance and mismatched direction, of vias on the chip  150 . Therefore, if the sensitivity of detecting via mismatch needs to be increased, the corresponding distance  295  between vias has to be decreased. 
     Moreover, in order to increase the sensitivity of detecting via mismatch for obtaining an accurate mismatched distance of via while the vias on the chip are mismatched, a method is utilized for increasing the sensitivity of detecting mismatch, wherein the method comprises: utilizing a plurality of metal lines in the metal layer  110  of process via mismatch detecting device; increasing the quantity of vias placed in the dielectric layer between the metal layer  105  and the metal layer  110 ; and decreasing the corresponding distance between each of the vias. The related description is shown in the following example. 
     Please referring to FIG. 4, FIG. 4 is a top perspective view showing another embodiment of present invention. In FIG. 4, if the process via mismatch detecting device of the present invention is applied on a chip having two metal layers, the process via mismatch detecting device is constituted with a detecting circuit  300  and a register  175 . The detecting circuit  300  is mainly constituted with two metal layers (i.e. a metal layer  105  and a metal layer  110 ), and the metal lines of the metal layer  105  are placed orthogonally to the metal lines of the metal layer  110 , and there is a dielectric layer (not shown) formed between the metal layer  105  and the metal layer  110 . 
     If the metal layer  105  is composed of a metal line  340  and a metal line  345 , and the required detecting range of detecting via mismatch range is about 0.12 μm, and the required sensitivity of detecting via mismatch is about 0.03 μm (herein the required sensitivity of detecting via mismatch is equal to the corresponding distance  295 ), and the size  350  of a via  375  is about 0.28 μm, the quantity of metal lines of the metal layer  110  can be resolved according to a formula (1) of predetermined via placement method. 
     
       
         the quantity of metal lines of the second metal layer =(the required detecting range)/ 
       
     
     
       
         (the required sensitivity of detecting via mismatch) x 2−1   Formula (1); 
       
     
     Let say the metal layer  105  is the first metal layer and the metal layer  110  is the second metal layer in the formula (1). Based on the required detecting range of detecting via mismatch range, which is about 0.12 μm, and the required sensitivity of detecting via mismatch, which is about 0.03 μm, the quantity of metal lines included in the metal layer  110  is seven by utilizing the formula (1). That means the metal layer  110  is at least composed of seven metal lines (i.e. metal lines  305 ,  310 ,  315 ,  320 ,  325 ,  330  and  335 ), so that the metal lines  340 , 345 ,  305  and  335  are formed to a rectangular  205 , within which the vias are placed in subsequent steps. 
     Moreover, according to the required detecting range of detecting via mismatch range, which is about 0.12 μm, and the size  350  of via  375 , which is about 0.28 μm, it is further known that in FIG. 4 the metal line distance  370  between the metal line  340  and the metal line  345  is about 0.52 μm, and the corresponding distance  390  between the metal line  340  and the via  375  in the dielectric layer corresponding to the metal line  305  is about 0.03 μm (equal to the required sensitivity of detecting via mismatch), and the corresponding distance  395  between the metal line  345  and the via  375  in the dielectric layer corresponding to the metal line  335  is about 0.03 μm (equal to the required sensitivity of detecting via mismatch). Meanwhile, the corresponding distance  385  between vias  375  is about 0.03 μm also(equal to the required sensitivity of detecting via mismatch). 
     Furthermore, as shown in FIG. 4, the metal lines  340  and  345  of the metal layer  105  are electrically connected to the power source  215  respectively. A terminal of each of the metal lines of the metal layer  110  is electrically connected to a resistor  220 , and each of the resistors  220  is electrically connected to the ground  240  respectively. Another terminal of each of the metal lines of the metal layer  110  is electrically connected to a register  175  through a buffer module  225  respectively. 
     By utilizing the process via mismatch detecting device  170  shown in FIG. 4, if the mismatched distance of vias between the metal layers on the chip  150  is between about 0.03 μm to about 0.06 μm along the negative x direction, the vias  375  on the process via mismatched detecting device  170  are also mismatched between about 0.03 μm to about 0.06 μm along the negative x direction as well. Because the corresponding distance  390  between the metal line  340  and the via  375  in the dielectric layer corresponding to the metal line  305  is about 0.03 μm, the metal line  340  can be electrically conducted with the metal line  305  through the mismatched via  375 . Meanwhile, since the metal line  340  is electrically connected to the power source  215 , the potential of the metal line  305  is increased after the metal line  305  is short-circuited with the metal line  340 . However, the potentials of other metal lines on the metal layer  110  still stay low, because other metal lines on the metal layer  110  are not electrically conducted with the metal line  340  or the metal line  345  through mismatched vias  375 . Therefore, the register  175  records that the input terminal  405  has a high potential and other input terminals have low potentials. After checking the result outputted from the output terminal  400  of register  175 , the personals can know that the mismatched distance of vias between the metal layers on the chip  150  is between about 0.03 μm to about 0.06 μm along the negative x direction. 
     Similarly, if the mismatched distance of vias between the metal layers on the chip  150  is between about 0.03 μm to about 0.06 μm along the positive x direction, the vias  375  of process via mismatched detecting device are also mismatched between about 0.03 μm to about 0.06 μm along the positive x direction as well. Because the corresponding distance  395  between the metal line  345  and the via  375  in the dielectric layer corresponding to the metal line  335  is about 0.03 μm, the metal line  345  is electrically conducted with the metal line  335  through the mismatched via  375 . Meanwhile, since the metal line  345  is electrically connected to the power source  215 , the potential of the metal line  335  is increased after the metal line  335  is short-circuited with the metal line  345 . However, the potentials of other metal lines of the metal layer  110  still stay low, because other metal lines on the metal layer  110  are not electrically conducted to the metal line  340  or the metal line  345  through the mismatched vias  375 . Therefore, the register  175  records that the input terminal  410  has a high potential and other input terminals have low potentials. After checking the result outputted from the output terminal  400  of the register  175 , the personals can know that the mismatched distance of vias between the metal layers on the chip  150  is between about 0.03 μm to about 0.06 μm along the positive x direction. 
     On the other hand, if the mismatched distance of vias between the metal layers on the chip  150  is from about 0.06 μm to about 0.09 μm along the negative x direction, the vias  375  on the process via mismatched detecting device  170  are also mismatched between about 0.06 μm to about 0.09 μm along the negative x direction as well. Because the corresponding distance  390  between the metal line  340  and the via  375  in the dielectric layer corresponding to the metal line  305  is about 0.03 μm, and the corresponding distance from the metal line  340  to the via  375  in the dielectric layer corresponding to the metal line  310  is about 0.06 μm (i.e. the corresponding distance  390  plus the corresponding distance  385  between two vias  375 ), thus, the metal line  340  is electrically conducted with the metal line  305  through the mismatched via  375 , and the metal line  340  can be electrically conducted with the metal line  310  through the mismatched via  375 . Meanwhile, since the metal line  340  is electrically connected to the power source  215 , the potential of the metal line  305  is increased after the metal line  305  is short-circuited with the metal line  340 , and the potential of the metal line  310  is increased after the metal line  310  is short-circuited with the metal line  340 . However, the potentials of other metal lines on the metal layer  110  still stays low, because other metal lines on the metal layer  110  can not be electrically conducted with the metal line  340  or the metal line  345  through the mismatched vias  375 . Therefore, the register  175  records that the input terminal  405  and the input terminal  415  have a high potential, and other input terminals have low potentials. After checking the result outputted from the output terminal  400  of register  175 , the personals can know that the mismatched distance of vias between the metal layers on the chip  150  is between about 0.06 μm to about 0.09 μm along the negative x direction. 
     Similarly, if the mismatched distance of vias between the metal layers on the chip  150  is between about 0.06 μm to about 0.09 μm along the positive x direction, the vias  375  on the process via mismatched detecting device are also mismatched between about 0.06 μm to about 0.09 μm along the positive x direction as well. Because the corresponding distance  395  between the metal line  345  and the via  375  in the dielectric layer corresponding to the metal line  335  is about 0.03 μm, and the corresponding distance between the metal line  345  and the via  375  in the dielectric layer corresponding to the metal line  330  is about 0.06 μm (i.e. the corresponding distance  395  plus the corresponding distance  385  between two vias  375 ), thus, the metal line  345  can be electrically conducted with the metal line  335  through the mismatched via  375 , and the metal line  345  can be electrically conducted with the metal line  330  through the mismatched via  375 . Meanwhile, since the metal line  345  is electrically connected to the power source  215 , the potential of metal line  335  is increased after the metal line  335  is short-circuited with the metal line  340 , and the potential of metal line  330  is increased after the metal line  330  is short-circuited with the metal line  340 . However, the potentials of other metal lines on the metal layer  110  still stays low, because other metal lines on the metal layer  110  can not be electrically conducted with the metal line  340  or the metal line  345  through mismatched vias  375 . Therefore, the register  175  records that the input terminal  410  and the input terminal  420  have a high potential, and other input terminals have low potentials. After checking the result outputted from the output terminal  400  of the register  175 , the personals can know that the mismatched distance of vias between the metal layers on the chip  150  is between about 0.06 μm to about 0.09 μm along the positive x direction. 
     In the process via mismatch detecting device  170  shown in FIG. 4, the corresponding distance  385  between two vias  375  is about 0.03 μm; the corresponding distance  390  between the metal line  340  and the via  375  in the dielectric layer corresponding to the metal line  305  is about 0.03 μm; the corresponding distance  395  between the metal line  345  and the via  375  in the dielectric layer corresponding to the metal line  335  is about 0.03 μm; the corresponding distance between the metal line  340  and the via  375  in the dielectric layer corresponding to the metal line  320  and the corresponding distance between the metal line  345  and the via  375  in the dielectric layer corresponding to the metal line  320  are about 0.12 μm. Thus, when the vias between the metal layers on the chip  150  are mismatched along the positive x direction or the negative x direction, and the mismatched distance is between about 0.03 μm to about 0.12 μm, the operation theorem of process via mismatch detecting device  170  as shown in FIG. 4 is the same as the description above. After checking the potential of each of the metal lines of metal layer  110  from the output terminal  400  of the register  175 , the mismatched direction and mismatched distance of vias between the metal layers on the chip  150  can be known, so as to perform the corresponding optimization. 
     In FIG.  3  and FIG. 4, the process via mismatch detecting device  170  according to the present invention is applied on a chip having two metal layers, and the process via mismatch detecting device  170  is mainly composed of a detecting circuit  300  and the register  175 , wherein the detecting circuit  300  is composed of two metal layers, i.e. the metal layer  105  and the metal layer  10 . 
     When the process via mismatch detecting device  170  according to the present invention is applied on a chip having more than two metal layers, please refer to FIG. 5, wherein FIG. 5 is a cross-sectional diagram showing the process via mismatch detecting device of present invention applied on a chip having three metal layers. As shown in FIG. 5, since a chip  500  has three metal layers, i.e. a metal layer  505 , a metal layer  510  and a metal layer  515 , wherein there are dielectric layers covering each of the metal layers for insulation. Thus, the process via mismatch detecting device located on the second region  145  of the chip  500  has two detecting circuits corresponding to the three metal layers of chip  500  for detecting the mismatch situation of vias among the metal layers. 
     In order to discriminate the mismatch of vias  485  between the metal layer  505  and the metal layer  510  from the mismatch of vias  490  between the metal layer  510  and metal layer  515 , the process via mismatch detecting device shown in FIG. 5 further comprises a metal-layer insulation module in each of the detecting circuits and an addressing module for discriminating and recording detected results of via mismatch on different metal layers. With regard to the connection of the addressing module; metal-layer insulation modules; each of the metal layers in the process via mismatch detecting device; and the operation thereof, please refer to FIG.  6 . 
     FIG. 6 is a diagram showing the connection of each of the components in a preferred embodiment of the present invention according to FIG.  5 . As shown in FIG. 6, in order to detect the mismatched distance of vias between the metal layer  505  and the metal layer  510  on the chip  500  and to detect the mismatched distance of vias between the metal layer  510  and the metal layer  515  on the chip  500 , the process via mismatch detecting device  170  is composed of a register  175 , an addressing module  520  and two detecting circuits (i.e. a detecting circuit  530  and a detecting circuit  535 ), wherein each of the detecting circuits further comprises a metal-layer insulation module. The components forming each of the detecting circuits and the operation theorem of the process via mismatch detecting device  170  are described as follows. 
     Please referring to FIG. 6, FIG.  7  and FIG. 8, FIG. 7 is a top perspective view showing a preferred embodiment of the present invention according to FIG. 5, and FIG. 8 is a top perspective view showing a preferred embodiment of the present invention according to FIG.  5 . For conveniently describing the operation theorems concerning the addressing module  520  and the metal-layer insulation module  555 , the detecting circuit  535  shown in FIG. 6 is not shown in FIG.  7 . The constitution of the detecting circuit  530  shown in FIG. 7 is similar to that of the detecting circuit  300  shown in FIG. 4, but the difference between detecting circuit  530  and the detecting circuit  300  are that the detecting circuit  530  shown in FIG. 7 is electrically connected to the register  175  through the metal-layer insulation module  555 . 
     If the required detecting range of detecting via mismatch range is about 0.12 μm, and the required sensitivity of detecting via mismatch is about 0.03 μm, and the size  635  of each via  525  is about 0.28 μm, according to the formula (1), the quantity of metal line of the metal layer  505  shown in FIG. 7 is seven (i.e. metal lines  570 ,  575 ,  580 ,  585 ,  590 ,  595  and  600 . The metal layer  510  shown in FIG. 7 is composed of a metal line  540  and a metal line  545 . 
     Thus, according to the required detecting range of detecting via mismatch range and the size  635  of via  525 , the metal line distance  605  between the metal line  540  and the metal line  545  can be resolved and is about 0.54 μm, and the corresponding distance  615  between vias  525  is about 0.03 μm, and the corresponding distance  620  between the metal line  540  and the via  525  in the dielectric layer corresponding to the metal line  570  is about 0.03 μm, and the corresponding distance  625  between the metal line  545  and the via  525  in the dielectric layer corresponding to the metal line  600  is about 0.03 μm, and both the corresponding distance  630  between the metal line  540  and the via  525  in the dielectric layer corresponding to the metal line  585  and the corresponding distance  630  between the metal line  545  and the via  525  in the dielectric layer corresponding to the metal line  585  are 0.12 μm, wherein all vias shown in FIG. 7 are placed within the rectangular  610 . 
     While detecting the mismatch distance of vias between the metal layer  505  and the metal layer  510 , a first predetermined address is inputted to the addressing module  520  of the process via mismatch detecting device  170  as shown in FIG.  6 . After the first predetermined address in the addressing module  520  is decoded, a power supply module  495  is activated to supply power to the metal lines  540  and  545  of the metal layer  510 , and the metal-layer insulation module  550  (shown in FIG. 8) of the detecting circuit  535  is activated and the metal-layer insulation module  555  of the detecting circuit  530  is stopped, so that the detected result of via mismatch generated by the detecting circuit  530  can be saved in the register  175  through the metal-layer insulation module  555 , and the circuit between the register  175  and detecting circuit  535  is opened and interrupted in order to avoid any signal or noise influencing the detected result of via mismatch generated by the detecting circuit  530 . 
     In FIG. 8, similarly, in order to conveniently describe the operation theorems of the addressing module  520  and the metal-layer insulation module  550 , the detecting circuit  530  shown in FIG. 6 is not shown in FIG.  8 . The constitution of the detecting circuit  535  shown in FIG. 8 is similar to that of the detecting circuit  530  shown in FIG.  7 . 
     If the required detecting range of detecting via mismatch range is 0.16 μm, and the required sensitivity of detecting via mismatch is about 0.04 μm, and the size  710  of via  705 , is about 0.28 μm, according to the formula (1), the metal layer  510  shown in FIG. 8 is constructed by seven metal lines (i.e. the metal lines  670 ,  675 ,  680 ,  685 ,  690 ,  695  and  700 ). Therefore, according to FIG. 6, FIG.  7  and FIG. 8, it is known that total metal lines in the metal layer  510  are nine metal lines: the metal lines  540 ,  545 ,  670 ,  675 ,  680 ,  685 ,  690 ,  695  and  700 . Moreover, the metal layer  515  is constructed by the metal lines  560  and  565 . The detecting circuit  535  shown in FIG. 8 is electrically connected to the register  175  through the metal-layer insulation module  550 . 
     Thus, according to the required detecting range of detecting via mismatch range and the size  710  of via  705 , the metal line distance  665  between the metal line  560  and the metal line  565  can be resolved and is about 0.60 μm, and the corresponding distance  645  between vias  705  is about 0.04 μm, and the corresponding distance  650  between the metal line  560  and the via  705  in the dielectric layer corresponding to the metal line  670  is about 0.04 μm, and the corresponding distance  655  between the metal line  565  and the via  705  in the dielectric layer corresponding to the metal line  700  is about 0.04 μm, and both the corresponding distance  660  between the metal line  560  and the via  705  in the dielectric layer corresponding to the metal line  685  and the corresponding distance  660  between the metal line  565  and the via  705  in the dielectric layer corresponding to the metal line  685  are 0.16 μm, wherein all vias shown in FIG. 8 are placed within the rectangular  640 . 
     Similarly, while detecting the mismatch distance of vias between the metal layer  510  and the metal layer  515 , a second predetermined address is inputted to the addressing module  520  of the process via mismatch detecting device  170  shown in FIG.  6 . After the first predetermined address in the addressing module  520  is decoded, a power supply module  495  is activated to supply power to the metal lines  560  and  565  of the metal layer  515 , and the metal-layer insulation module  555  of the detecting circuit  530  is activated and the metal-layer insulation module  550  of detecting circuit  535  is stopped, so that the detected result of via mismatch generated by the detecting circuit  535  can be saved in the register  175  through the metal-layer insulation module  550 , and the circuit between the register  175  and the detecting circuit  530  is interrupted as an open circuit to avoid any signal or noise influencing the detected result of via mismatch generated by the detecting circuit  535 . The operation theorem of the process via mismatch detecting device  170  shown in FIG. 6, FIG.  7  and FIG. 8 is described as that of the process via mismatch detecting device  170  shown in FIG.  3  and FIG. 4 above, so the related description is omitted. 
     Furthermore, the values of the required detecting range of detecting via mismatch range, the required sensitivity of detecting via mismatch and etc., recited in FIG. 3, FIG. 4, FIG.  7  and FIG. 8 are used to describe the operation of the present invention in samples. Thus, the related values can be modified and adjusted according to different designs while implementing the present invention. Moreover, each component in the process via mismatch detecting device  170  of the present invention can be formed and manufactured by known semiconductor techniques, such as depositing, sputtering, etc. 
     In FIG. 6, FIG.  7  and FIG. 8, the embodiment of the present invention is applied on a chip having three metal layers. If the process via mismatch detecting device  170  of the present invention is applied on a chip having four metal layers, an embodiment of the present invention can be composed of a register  175 , an addressing module  520 , a power supply module  495  and at least three detecting circuits, wherein each of the detecting circuits comprises a metal-layer insulation module, a plurality of resistors and a plurality of metal lines that are corresponding to each other but located on different metal layers. Moreover, the process via mismatch detecting device  170  of the present invention can also be applied on the detection of contact mismatch between the substrate and the metal layer that is formed above the substrate, and the operation theorem is similar to that of detecting via mismatch between metal layers. 
     Hence, the process via mismatch detecting device  170  of the present invention can be modified according to the quantity of the metal layers in a chip, and meanwhile, the locations of vias placed and the quantity of metal lines in a detecting circuit can also be modified according to the required sensitivity of detecting mismatch and the required detecting range of detecting via mismatch range. In addition, if the detecting circuit shown in FIG. 3, or FIG. 4, or FIG. 7, or FIG. 8 is implemented after being rotated ninety degrees horizontally, the via mismatch along the y direction can be detected by the process via mismatch detecting device of the present invention. 
     Please referring to FIG. 9, FIG. 9 is a top perspective view showing another embodiment of the present invention that is used to detect the via mismatch along the y direction and is applied on a chip having two metal layers, wherein the process via mismatch detecting device  170  shown in FIG. 9 is similar to the process via mismatch detecting device  170  shown in FIG. 4, but the differences are that the metal line  305 , the metal line  310 , the metal line  315 , the metal line  320 , the metal line  325 , the metal line  330  and the metal line  335  are electrically connected to the register  175  through a metal-layer insulation module  750 ; and the power supply module  495  and the metal-layer insulation module  750  are controlled by an addressing module  520 . Therefore, the detecting circuit shown in FIG. 4, or FIG. 7 or FIG.  8  and that shown in FIG. 9 can be utilized in the process via mismatch detecting device of the present invention and be connected with each other like the connection shown in FIG. 6 while the mismatches of vias between the metal layers along the x direction and the y direction are detected, so that the goal of simultaneously detecting the via mismatch along the x direction and the y direction is achieved. 
     In conclusion, the quantity and placement direction of the detecting circuit; the quantity of metal lines in each of the metal layers of the detecting circuit; the placement and quantity of the vias; and the implementations of register, addressing module, metal-layer insulation module and power supply module are not limited to the descriptions of such as the aforementioned embodiments, and can be modified and adjusted in accordance with the quantity of metal layers on a chip, etc., in the process via mismatch detecting device of the present invention, so that the process via mismatch detecting device of the present invention has the advantages of broader utilization and flexible design. 
     The advantage of the present invention is to provide a process via mismatch detecting device. While the vias between the metal layers on the chips are mismatched, the vias on the detecting circuits of the process via mismatch detecting device are mismatched as well, so as to trigger the short circuits between different metal lines located on different metal layers by appropriately placing the vias on the detecting circuits after vias of detecting circuits are mismatched, and then the detected result of via mismatch is outputted. Therefore, the process via mismatch detecting device can find out whether the vias between the metal layers on the chip are mismatched or not and obtain the mismatch direction and the mismatch distances efficiently and accurately, so as to make an appropriate adjustment and optimization on a process. 
     As is understood by a person skilled in the art, the foregoing preferred embodiments of the present invention are illustrated of the present invention rather than limiting of the present invention. It is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structure.

Technology Category: 5