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Via Chains for Image-Based measurement of health of line by photon emission

IP.com Disclosure Number: IPCOM000239409D
Publication Date: 2014-Nov-05
Document File: 5 page(s) / 79K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a system for monitoring the health of a line in a semiconductor manufacturing process involving collecting photon emission image(s) with information about the shorting mechanisms of multiple differing cells stressed in parallel.

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Via Chains for Image-Based measurement of health of line by photon emission

It is very important in semiconductor yield management and performance optimization to have a quick answer as to whether there were "shorts" vs. "leakages", as the process fixes are entirely different. This is a difficult determination to make, however.

A method is needed to determine whether a contact-diffusion-gate system has contact-to-gate shorts (e.g., CA to PC), or leakages (e.g., gate dielectric, diode integrity, channel leakage, etc.).

Consider a device having contact array (300), a gate (310), diffusion (320), a channel (330), and a silicide contact (340), as shown in Figure 1.

Figure 1: Healthy device

Figure 2 shows one type of defect mode, prone to causing device leakage, a silicide intrusion into the channel.

Figure 2: High current due to channel leakage

Figure 3 shows an alternative type of defect mode, where contact array (300) is

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misaligned relative to gate (310), leading to a direct short.

Figure 3: Short in device due to contact array misalignment

Current solutions build test structures to test various device properties at M1. The macros may have various critical dimensions, intentional misalignments, pitches, implant conditions, gate dielectric flavors, etc. Each individual array is tested, often at a single voltage. The measured current is then compared to a specification. Individual failing chips are then submitted to failure analysis (FA). A typical failure analysis approach involves testing arrays under photon-based techniques (such as Photon Emission (PEM), or Optical Beam Induced Resistance Change (OBIRCH). The FA technique then is used to pinpoint the location of point defects, which are then examined by various physical methods (TEM, SEM, etc.). From interpretation of the physical FA, one can make inferences as to the nature of the defect mechanism. The problem is that this approach can be very costly and time consuming, especially if one wants to explore a wide range of device properties.

The solution involves a test structure, which involves parallel (simultaneous) voltage stressing of multiple arrays, each of which may contain elements of different character (e.g., pitches, dimensions, misalignments, implant conditions, gate dielectrics, etc.). The testing is performed in an enclosed system with an Indium Gallium Arsenide (InGaAs) or other photon emission camera. A photon emission image is therefore generated. The image has multiple spots in it, which may vary according to...