Abstract:
A method for determining a usage fee for a digital photolithography system is provided. The method is implemented as a computer program in a computer system used with the digital photolithography system. A digital mask is first received into the computer system, the digital mask being a source of pattern information for a digital pattern generator. Whenever a portion of the digital mask is transferred to the digital pattern generator, the transfer is detected and a counter is updated, accordingly. This is done only if the first digital mask is new. The usage fee can thereby be determined from the counter.

Description:
BACKGROUND  
         [0001]    The present invention relates generally to business methods for leasing/purchasing a maskless, digital photolithography system, such as can be used for printed circuit board or semiconductor fabrication.  
           [0002]    Photolithography is a complicated and expensive processing operation for fabricating semiconductor wafers, printed circuit boards, and the like. For example, a photolithography system used for wafer fabrication may cost several hundred thousand dollars, or more, of initial investment. Furthermore, photolithography systems require constant maintenance and alignment to allow the systems to achieve very precise exposures.  
           [0003]    In addition to the system costs, conventional photolithography systems must use one or more very expensive masks. Masks are transparent plates that provide a high-contrast pattern to be exposed onto a substrate (e.g., a wafer). For example, a mask may be a quartz plate with a patterned chromium film on it. It is typical for the photolithography system to use many different masks to expose a complex, multi-layer integrated circuit onto the wafer. Therefore, the different masks must be continually inserted in and removed from the photolithography system for the overall fabrication of the wafer.  
           [0004]    Masks must also be replaced on a relatively frequent basis. Improvements in pattern design and normal damage from continued use require old masks to be discarded and new masks provided in their place. Therefore, masks can represent a continually recurring cost in wafer fabrication.  
           [0005]    In U.S. Ser. No. 09/348,369, which is commonly assigned with the present invention and is hereby incorporated by reference, a maskless photolithography system is provided. For various reasons, however, many users of photolithography systems are reluctant to purchase such a maskless system. For example, the high initial cost of any photolithography system prevents users from such a purchase. Also, since the maskless technology is relatively new, many users will wait to see if the technology is indeed worthwhile.  
           [0006]    Therefore, what is needed is a method for “selling” maskless photolithography systems that will be advantageous and desirable for both the seller and the user of such systems.  
         SUMMARY  
         [0007]    A technical advance is provided by a new and unique method for “selling” a digital photolithography system. In the preferred embodiment, the photolithography system includes a computer system and a digital pattern generator for performing digital photolithography on a substrate such as a wafer for multi-layered integrated circuits.  
           [0008]    The method, all or part of which can be implemented as a computer program in the computer system, includes instructions for receiving a first digital mask into the computer system. The first digital mask is a source of pattern information for the digital pattern generator. Whenever a portion of the first digital mask is transferred to the digital pattern generator, the method detects the transfer and updates a counter, accordingly. This is done only if the first digital mask is new.  
           [0009]    A usage fee can thereby be determined from the counter. In some embodiments, the usage fee is calculated as a function of a predetermined reference value, such as a typical cost for a conventional, physical mask. In some embodiments, the reference value changes for each new mask that is transferred to the digital pattern generator.  
           [0010]    Therefore, the present invention provides a method for “selling” maskless photolithography systems that will be advantageous and desirable for both the seller and the user of such systems.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 illustrates a maskless photolithography system including a pattern generator and mask pattern design system for implementing embodiments of the present invention.  
         [0012]    [0012]FIG. 2 presents the pattern generator and mask pattern design system of FIG. 1 in further detail.  
         [0013]    [0013]FIG. 3 is a flow chart of a method that is used to perform the business method of the present disclosure. 
     
    
     DETAILED DESCRIPTION  
       [0014]    The present disclosure relates to business models and methods, such as can be used with maskless photolithography systems. It is understood, however, that the following disclosure provides many different embodiments, or examples, for implementing different features of the invention in specific applications. These embodiments are, of course, merely examples and are not intended to limit the invention from that described in the claims.  
         [0015]    The present disclosure is divided into four different sections. The first section describes an exemplary maskless photolithography system. The second section describes a business method for “selling” the maskless photolithography system to an end user. The third section concludes by describing some of the many advantages of the methods previously discussed.  
         [0016]    Exemplary System  
         [0017]    Referring to FIG. 1, a maskless photolithography system  30 , such as is disclosed in presently incorporated U.S. Ser. No. 09/348,369, can benefit from the present invention. The maskless photolithography system  30  includes a light source  32 , a first lenses system  34 , a mask pattern system  36 , a pattern generator  38 , and a second lenses system  40 . The system operates on a subject  42 , which is positioned on a subject stage  44 . A resist layer or other energy-sensitive coating  46  is disposed on the subject  42 .  
         [0018]    The light source  32  and the lens systems  34 ,  40  may be of various types, depending on the requirements of a specific application. Selection of such components is well known by those of ordinary skill in the art. The mask pattern system  36  may be one or more typical computers with necessary processing capability, storage, and interface, as will be discussed below. The pattern generator  38  may be a digital/deformable mirror device, a liquid crystal display, a spatial light modulator, or other appropriate pixel-panel device, and may include appropriate drivers and memory.  
         [0019]    In operation, the light source  32  provides a collimated beam of light  48  which is projected through the first lenses system  34  and onto the pattern generator  38 . The pattern generator  38  is provided with mask information via suitable signal line(s)  37  from the mask pattern system  36 . The mask information may represent an entire digital mask, or a portion of the digital mask, as required. The mask information is used by the pattern generator  38  to produce a digital mask pattern for a desired duration. Light emanating from the digital mask pattern of the pattern generator  38  then passes through the second lenses system  40  and onto the subject  42 . In this manner, the digital mask pattern of the mask generator  38  is projected onto the resist coating  46  of the subject  42 .  
         [0020]    In some embodiments, any modifications and/or changes required in the digital mask can be made using the mask pattern system  36 . As a result, the need for fabrication of a new physical mask, as would be required in conventional photolithography systems, is thus eliminated by the photolithography system  30  of the present disclosure. Also, changing digital masks for different exposure operations is done electronically, thereby eliminating the wear and tear associated with typical physical mask operations. As a result, substantial cost savings are realized in the manufacture of subjects which require the use of a patterning of a photo resist coated subject.  
         [0021]    In addition, the present photolithography system  30  reduces a lead time associated with obtaining a particular mask, in addition to a reduced repair time in the event that changes to the mask become necessary after an initial design implementation. In other words, the lead time and repair time of producing a digital mask are almost negligible, as compared with conventional physical masks.  
         [0022]    Referring now to FIG. 2, the mask pattern system  36  may include (either as a separate computer or a separate routine running in the same computer) a computer aided mask pattern design system for creating a desired digital mask. The digital mask may, for example, be stored in a memory  38  in the form of a bit map or the like. The bit map can include individual pixel data, which is subject to easy modification as may be required for the development of a particular integrated circuit design and/or mask pattern design.  
         [0023]    With the use of the computer aided pattern design system  36 , any bit can be easily changed or its location moved in a particular digital mask. Also, the digital mask can be changed or aligned as needed almost instantly with the use of an appropriate instruction from the computer aided pattern design system  36 . In some embodiments, the computer aided pattern design system  36  may also be used for creating and simulating a circuit from initial design through any and all necessary design changes and/or modifications to the final digital masks. Once created, the digital masks may also be used for the creation of a conventional printed mask, such as can be used in a conventional photolithography system.  
         [0024]    Once the digital mask has been constructed and saved in the memory  38 , it can be provided to the display panel  38 , as shown by memory bit map  40 . In some embodiments, mask information representing only a portion of the entire mask pattern may to be delivered to the display panel  38 . This allows the system  36  to accommodate data bottlenecks, such as available bandwidth in the signal lines  37  or the size and/or available memory in the display panel  38  (or associated drivers).  
         [0025]    Business Method  
         [0026]    Referring now to FIG. 3, a method  100  provides a new and unique way to monitor the activity of the photolithography system  30 , and to measure payments for such activity. As a result, the method  100  may be used to compensate an owner or manufacturer of the system  30  for its use. Such compensation may be used in lieu of, or in addition to, the user paying a purchase price for the system. For example, the user may purchase the system hardware, and the method  100  may calculate software license payments for the software on a per-use basis.  
         [0027]    The method  100  begins at step  102 , when the user receives the photolithography system  30 . The method  100  may be a software routine that runs on the mask pattern system  36  of FIG. 2. Part of the initial step of receiving the system  30  may include entering a userid into the software routine to activate the method  100  and to enable the system. The method  100  continues to run on the mask pattern system  36 , and may be protected from improper access by various security measures well known in the art.  
         [0028]    In the present example, the user does not purchase the system, but pays for the system based on the number of new digital masks used by the system. At step  104 , one or more digital masks are provided. The digital masks may be created using the computer aided pattern design system  36  discussed above, or may be converted from an existing mask. For example, conventional digital data used to create a physical mask, or to run simulations on a desired integrated circuit, can be easily converted to the digital masks used in the system  30 .  
         [0029]    At step  106 , the software routine detects when mask information is transferred to the pattern generator  38 . In the present embodiment, the software routine specifically detects when mask information relating to a new or different digital mask is being transferred. In this way, a single digital mask can be repeatedly used, without incurring extra expense. In addition, for embodiments that do not transfer the entire digital mask at one time, but instead send portions to the pattern generator, the different portions are not perceived as new digital masks.  
         [0030]    At step  108 , each time a “new” digital mask is transferred to the pattern generator  38 , a charge fee counter  110  is incremented. The method  100  continually checks for new digital masks, and updates the charge fee counter  110  accordingly. In some embodiments, a “new” digital mask is one that has never been transferred to the pattern generator  38 . This may include modified masks (e.g., small changes were made to a previous mask), or brand new masks that relate to other layers or other circuit designs. In other embodiments, a “new” digital mask is simply a different mask than the immediate prior digital mask being used by the pattern generator  38 .  
         [0031]    At periodic intervals, the charge fee counter  110  is reviewed for payment. In one embodiment, each “new” digital mask is set to a predetermined reference value. One example of a predetermined reference value is a standard market cost of a conventional, physical mask. In another embodiment, different fees apply to brand new masks, modified masks, and different masks. Table 1, below, shows one such fee arrangement.  
                           TABLE 1                                   Type of New Mask   Cost (compared to reference values)                           brand new   50%           modified   30%           different    5%                      
 
         [0032]    In furtherance of the example, if a conventional, physical mask costs one hundred thousand dollars, each brand new mask used by the system  30  will accrue a charge of fifty thousand dollars, each modified mask will accrue a charge of thirty thousand dollars, and each different mask will accrue a charge of five thousand dollars.  
         [0033]    The charge fee counter  110  may also include an indicator that identifies a resolution of the digital mask. The above described fees may be modified for different resolution masks, which corresponds to the higher costs for conventional physical masks with high resolution. In this way, the reference value for each mask may be individually set by the corresponding cost of the alternative conventional physical mask that would provide the same resolution. Continuing the above-described example, a conventional physical mask used for  1  micron resolution may cost twenty thousand dollars, while a conventional physical mask for  0 . 18  micron resolution may cost one hundred thousand dollars.  
         [0034]    Conclusion  
         [0035]    The methods, routines, and applications discussed above provide many advantages. For one, the user does not have to purchase the photolithography system, which makes the user more likely to try the system.  
         [0036]    Another advantage is that the costs associated with running the system are directly related to the cost of purchasing conventional, physical masks. Therefore, the operating cost of using the digital photolithography system tracks, or follows, traditional costs. So, if the mask pattern does not change, the fees are relatively low, as it would be for a conventional photolithography system.  
         [0037]    Another advantage is that the system can be used for high resolution masks and low resolution masks, with the associated costs further tracking the cost of purchasing conventional, physical masks for the same purpose.  
         [0038]    While the invention has been particularly shown and described with reference to the preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing form the spirit and scope of the invention.