Abstract:
The operability of light-based semiconductor die analysis is enhanced using a method and arrangement that directs light between a light source and a die. In one example embodiment of the present invention, a light source is directed to a die in a semiconductor analysis arrangement using a fiber optic cable. The analysis arrangement is adapted to use light received via the fiber optic cable to analyze the die. The analysis includes one or more light-based applications, such as stimulating a selected portion of the die with the light and detecting a response therefrom. In this manner, light can be directed to a die in a variety of analysis implementations, such as for analyzing a die in a test chamber.

Description:
RELATED PATENT DOCUMENTS 
     This Application claims priority for common subject matter to U.S. Provisional Patent Application Ser. No. 60/198,365, filed on Apr. 19, 2000 and entitled “Semiconductor Analysis Arrangement and Method Therefor,” which is fully incorporated herein by reference. This application is further related to U.S. patent application Ser. No. 09/838,671, now U.S. Pat. No. 6,700,659, entitled “Semiconductor Analysis Arrangement and method Therefore”; to U.S. patent application Ser. No. 09/838,667, entitled “Semiconductor Analysis Using Thermal Control”; and to U.S. patent application Ser. No. 09/838,672, now U.S. Pat. No. 6,635,839 entitled “Semiconductor Analysis Arrangement and Method Therefor,” all of which are filed concurrently herewith. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to semiconductor device analysis and, more particularly, to devices and arrangements for fiber optic analysis of a semiconductor die. 
     BACKGROUND OF THE INVENTION 
     The semiconductor industry has recently experienced technological advances that have permitted dramatic increases in circuit density and complexity, and equally dramatic decreases in power consumption and package sizes. Present semiconductor technology now permits single-chip microprocessors with many millions of transistors, operating at speeds of hundreds of millions of instructions per second to be packaged in relatively small, air-cooled semiconductor device packages. A by-product of these technological advances has been an increase in the complexity of manufacturing of the devices, which has been accompanied by increased pressure to produce consistent and affordable products. 
     As the manufacturing processes for semiconductor devices and integrated circuits increase in complexity, methods for testing and debugging these devices become increasingly important. Not only is it important to ensure that individual chips are functional, it is also important to ensure that batches of chips perform consistently. In addition, the ability to detect a defective manufacturing process early is helpful for reducing the number of defective devices manufactured. 
     One type of semiconductor analysis involves conveniently directing perturbation, such as laser light, to a semiconductor device under test (DUT). When performing such analysis, however, there are many issues to be managed. These issues include concerns such as laser leakage, calibration problems, and functional deficiencies. Further, there is a need for convenient approaches to presenting various types of perturbation signals to the DUT, which can be particularly challenging when the analysis of the DUT is to be performed in a chamber or other arrangement that makes access to the DUT difficult. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an approach for semiconductor analysis that improves the efficiency of the analysis. The present invention is exemplified in a number of implementations and applications, some of which are summarized below. 
     The present invention is directed to addressing needs discussed above and is further useful in connection with the example embodiments disclosed in the above-referenced patent documents. According to an example embodiment of the present invention, a system for analyzing a semiconductor die includes a fiber optic cable adapted to direct light for die analysis. The system includes a light source and a fiber optic cable adapted to receive light from the source. A semiconductor die is held in an analysis arrangement, and light from the light source is directed via the fiber optic cable to perturb the die. In this manner, light can be directed to a die in a variety of applications, such as in a test chamber or in other arrangements where access to the die is challenging. 
     In a more particular example embodiment of the present invention, the semiconductor die is placed on a stage in a vacuum chamber and the light source is located outside of the chamber. A fiber optic cable extends from the light source and into the chamber. A vacuum is drawn on the chamber, and light from the light source is directed into the chamber via the fiber optic cable. The light is directed to a portion of the die that is to be stimulated using a light direction arrangement, such as a series of mirrors and positioning devices (e.g., servo motors coupled to one or more of: the mirrors, the fiber optic cable and the stage). 
     The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures and detailed description which follow more particularly exemplify these embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which: 
         FIG. 1  is semiconductor analysis system, according to an example embodiment of the present invention; 
         FIG. 2  shows a system adapted to analyze a semiconductor die, according to another example embodiment of the present invention; and 
         FIG. 3  is a flow diagram of a method for analyzing a semiconductor die, according to another example embodiment of the present invention. 
     
    
    
     While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not necessarily to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
     The present invention is believed to be applicable for a variety of different types of analysis, and the invention has been found particularly suited for die analysis involving light perturbation of the die. While the present invention is not necessarily limited to such devices, various aspects of the invention may be appreciated through a discussion of various examples using this context. 
     According to an example embodiment of the present invention, a semiconductor die (e.g., DUT) is analyzed using a fiber optic cable to direct light to the die. The die is held in an analysis arrangement, such as a test fixture, a stage or a test chamber. Light is generated at a light source and directed to the die via a fiber optic cable. The light incident upon the die perturbs the die, and the perturbation is used for analyzing the die. 
     The direction of light via the fiber optic cable is particularly useful for directing light to a selected portion of the die and for directing light to the die in an environment that may not be particularly suited for the generation of light. For example, when the die is in a test chamber, it is sometimes advantageous to maintain the light source outside of the chamber. In this instance, the fiber optic cable allows the light source to be located outside of the test chamber while maintaining the direction of the light to the die in the chamber. The outside location enables access to the light source while the chamber is maintained at a vacuum. 
       FIG. 1  shows a system  100  for analyzing a semiconductor die  102 , according to an example embodiment of the present invention. The system includes a test head  105  adapted to hold the die  102  and to dock with a chamber  110  via a coupling arrangement  140 . Once the test head is docked with the chamber, one or more perturbation devices  101 , including a light source  106  and other devices, such as a FIB, laser, sonic, microwave, electron beam or ion beam devices is used to analyze the die. Operation control data, such as chamber condition, die response, and other data, is provided to a controller  115 . The controller is further adapted to receive response data from the die, such as electrical data obtained from die outputs. The perturbation devices  101  are also optionally coupled to the controller  115 , and the controller can be adapted to control and receive feedback from the devices  101 . A monitor  120  is coupled to the controller  115  and adapted to display information such as response data, control data. In one particular implementation, the monitor is used as part of an interface for controlling the system  100 . For more information regarding the use of a controller in connection with the present invention, reference may be made to U.S. patent application Ser. No. 09/838,672, now U.S. Pat. No. 6,6335,839 entitled “Semiconductor Analysis Arrangement and Method Therefor.” 
     In a more particular example embodiment of the present invention,  FIG. 2  shows a fiber optic system  200  adapted to analyze a semiconductor die  275 . The die is placed on a die holder  270  in a test chamber  260 . In one implementation, the holder  270  is part of a docking arrangement  290  adapted to couple to and form a seal with the test chamber  260 . A light source  205  generates light and the generated light is directed to the die  275  via a fiber optic cable  210  and a die analysis arrangement  250 . In one implementation, the die analysis arrangement  250  is adapted to direct the light to a selected portion of the die using, for example, a series of mirrors and positioning devices (e.g., servo motors coupled to one or more of: the mirrors, the fiber optic cable and the stage). The selected portion is stimulated, and a response from the die is detected. The response may include, for example, an electrical response that can be detected via a connection to the die, or an emission from the die, such as light and/or electrons. In one particular implementation, the die analysis arrangement  250  includes a detector adapted to detect such an emission, and in another implementation (not shown), a separate detector is located in the test chamber  260 . 
     In another example embodiment of the present invention, a photodiode  220  is coupled to the fiber optic cable  210 , is communicatively coupled to a controller  280  via communications link  281  and is adapted to detect light leakage from the cable. In response to an amount of light that might leak from the cable, the photodiode generates a signal that is sent to the controller  280 . The controller receives the signal and uses it for controlling the analysis of the semiconductor die  275 . By detecting light leaking from the fiber optic cable, the corresponding response from the die can be more accurately analyzed because the amount of light incident upon the die can be detected and/or estimated. Any corresponding change in the stimulation or response to the amount of light is accounted for using the detected leakage. In addition, undesirable leakage levels can be avoided. For more information regarding the detection of light leakage, reference may be made to U.S. patent application Ser. No. 09/838,671, now U.S. Pat. No. 6,700,659 entitled “Semiconductor Analysis Arrangement and Method Therefor.” 
     In another example implementation of the present invention (not shown), a photodiode is located inside the chamber  260 . This is useful for various applications including those that benefit from the ability to detect light leakage within the chamber without necessarily accessing the inside of the chamber. For instance, one application involves drawing a vacuum on the chamber during die analysis. If the chamber needs to be opened, the vacuum is lost. By placing the photodiode inside the chamber, calibration, safety and other aspects of the light delivery through the fiber optic cable can be realized without necessarily opening the chamber and breaking the vacuum. This makes possible the analysis of a die under vacuum while realizing the benefits of monitoring the light delivery concurrently with the analysis. 
     The present invention is adaptable for types of analysis including light induced voltage alteration (LIVA), thermal induced voltage alteration (TIVA), optical beam induced current (OBIC) and critical timing path (CTP) analysis. For more information regarding example types of analysis that can be performed in connection with the present invention, reference maybe made to U.S. Pat. No. 5,430,305, filed on Apr. 8, 1994 and entitled “Light-induced Voltage Alteration for Integrated Circuit Analysis,” to U.S. Pat. No. 5,523,694, filed on Jun. 4, 1996 and entitled “Integrated Circuit Failure Analysis by Low-energy Charge-induced Voltage Alteration,” to U.S. Pat. No. 5,844,416, filed on Nov. 2, 1995 and entitled “Ion-beam Apparatus and Method for Analyzing and Controlling Integrated Circuits,” to U.S. patent application Ser. No. 09/259,542, now U.S. Pat. No. 6,177,989 filed on Mar. 1, 1999 and entitled “Laser Induced Current for Semiconductor Defect Detection,” and to U.S. patent application Ser. No. 09/385,775, now U.S. Pat. No. 6,541,987 filed on Aug. 30, 1999 and entitled “Laser-excited Detection of Defective Semiconductor Device,” which are fully incorporated herein by reference. 
       FIG. 3  is a flow diagram of a method for analyzing a semiconductor device, according to another example embodiment of the present invention. The die is placed into and held in an analysis arrangement at block  310 . Light is generated at block  320 , and the generated light is directed to the held die via a fiber optic cable at block  330 . In one implementation, a positioning arrangement is used to direct light from the fiber optic cable to a selected portion of the die. For example, a transistor in the die can be stimulated using a positioning arrangement having a reference for the location of the transistor. The light perturbs the die at block  340 , and a response to the perturbation is detected at block  350 . 
     While the present invention has been described with reference to several particular example embodiments, those skilled in the art will recognize that many changes may be made thereto without departing from the spirit and scope of the present invention, which is set forth in the following claims.