Methods and systems for low-force, low-temperature thermocompression bonding. The present application teaches new methods and structures for three-dimensional integrated circuits, in which cold thermocompression bonding is used to provide reliable bonding. To achieve this, reduction and passivation steps are preferably both used to reduce native oxide on the contact metals and to prevent reformation of native oxide, preferably using atmospheric plasma treatments. Preferably the physical compression height of the elements is set to be only enough to reliably achieve at least some compression of each bonding element pair, compensating for any lack of flatness. Preferably the thermocompression bonding is performed well below the melting point. This not only avoids the deformation of lower levels which is induced by reflow techniques, but also provides a steep relation of force versus z-axis travel, so that a drastically-increasing resistance to compression helps to regulate the degree of thermocompression.

Methods and systems for low-force, low-temperature thermocompression bonding. The present application teaches new methods and structures for three-dimensional integrated circuits, in which cold thermocompression bonding is used to provide reliable bonding. To achieve this, reduction and passivation steps are preferably both used to reduce native oxide on the contact metals and to prevent reformation of native oxide, preferably using atmospheric plasma treatments. Preferably the physical compression height of the elements is set to be only enough to reliably achieve at least some compression of each bonding element pair, compensating for any lack of flatness. Preferably the thermocompression bonding is performed well below the melting point. This not only avoids the deformation of lower levels which is induced by reflow techniques, but also provides a steep relation of force versus z-axis travel, so that a drastically-increasing resistance to compression helps to regulate the degree of thermocompression.

Apparatus and methods are disclosed for transferring solder to a substrate. A substrate belt moves one or more substrates in a belt direction. A decal has one or more through holes in a hole pattern that hold solder. Each of the solder holes can align with respective locations on one of the substrates. An ultrasonic head produces an ultrasonic vibration in the solder in a longitudinal direction perpendicular to the belt direction. The ultrasonic head and substrate can be moved together in the longitudinal direction to maintain the ultrasonic head in contact with the solder while the ultrasonic head applies the ultrasonic vibration. Various methods are disclosed including methods of transferring the solder with or without external heating.

A microscale selective laser sintering (-SLS) that improves the minimum feature-size resolution of metal additively manufactured parts by up to two orders of magnitude, while still maintaining the throughput of traditional additive manufacturing processes. The microscale selective laser sintering includes, in some embodiments, ultra-fast lasers, a micro-mirror based optical system, nanoscale powders, and a precision spreader mechanism. The micro-SLS system is capable of achieving build rates of at least 1 cm.sup.3/hr while achieving a feature-size resolution of approximately 1 m. In some embodiments, the exemplified systems and methods facilitate a direct write, microscale selective laser sintering -SLS system that is configured to write 3D metal structures having features sizes down to approximately 1 m scale on rigid or flexible substrates. The exemplified systems and methods may operate on a variety of material including, for example, polymers, dielectrics, semiconductors, and metals.

A method for use with multiple chips, each respectively having a bonding surface including electrical contacts and a surface on a side opposite the bonding surface involves bringing a hardenable material located on a body into contact with the multiple chips, hardening the hardenable material so as to constrain at least a portion of each of the multiple chips, moving the multiple chips from a first location to a second location, applying a force to the body such that the hardened, hardenable material will uniformly transfer a vertical force, applied to the body, to the chips so as to bring, under pressure, a bonding surface of each individual chip into contact with a bonding surface of an element to which the individual chips will be bonded, at the second location, without causing damage to the individual chips, element, or bonding surface.

A method for use with multiple chips, each respectively having a bonding surface including electrical contacts and a surface on a side opposite the bonding surface involves bringing a hardenable material located on a body into contact with the multiple chips, hardening the hardenable material so as to constrain at least a portion of each of the multiple chips, moving the multiple chips from a first location to a second location, applying a force to the body such that the hardened, hardenable material will uniformly transfer a vertical force, applied to the body, to the chips so as to bring, under pressure, a bonding surface of each individual chip into contact with a bonding surface of an element to which the individual chips will be bonded, at the second location, without causing damage to the individual chips, element, or bonding surface.

An apparatus for heating a substrate during die bonding is disclosed. The apparatus comprises: a substrate carrier configured to hold the substrate; a heating device configured to heat the substrate; a first actuator for effecting relative motion between the substrate carrier and the heating device such that the substrate is relatively indexed with respect to the heating device; a second actuator for effecting relative motion between the substrate carrier and the heating device such that the heating device contacts the substrate to heat different portions of the substrate. In particular, the second actuator is operative to separate the heating device from the substrate in order for the first actuator to relatively index the substrate across the heating device. A method of heating a substrate during die bonding is also disclosed.

Methods and systems for low-force, low-temperature thermocompression bonding. The present application teaches new methods and structures for three-dimensional integrated circuits, in which cold thermocompression bonding is used to provide reliable bonding. To achieve this, reduction and passivation steps are preferably both used to reduce native oxide on the contact metals and to prevent reformation of native oxide, preferably using atmospheric plasma treatments. Preferably the physical compression height of the elements is set to be only enough to reliably achieve at least some compression of each bonding element pair, compensating for any lack of flatness. Preferably the thermocompression bonding is performed well below the melting point. This not only avoids the deformation of lower levels which is induced by reflow techniques, but also provides a steep relation of force versus z-axis travel, so that a drastically-increasing resistance to compression helps to regulate the degree of thermocompression.

Methods and systems for low-force, low-temperature thermocompression bonding. The present application teaches new methods and structures for three-dimensional integrated circuits, in which cold thermocompression bonding is used to provide reliable bonding. To achieve this, reduction and passivation steps are preferably both used to reduce native oxide on the contact metals and to prevent reformation of native oxide, preferably using atmospheric plasma treatments. Preferably the physical compression height of the elements is set to be only enough to reliably achieve at least some compression of each bonding element pair, compensating for any lack of flatness. Preferably the thermocompression bonding is performed well below the melting point. This not only avoids the deformation of lower levels which is induced by reflow techniques, but also provides a steep relation of force versus z-axis travel, so that a drastically-increasing resistance to compression helps to regulate the degree of thermocompression.

Methods and systems for low-force, low-temperature thermocompression bonding. The present application teaches new methods and structures for three-dimensional integrated circuits, in which cold thermocompression bonding is used to provide reliable bonding. To achieve this, reduction and passivation steps are preferably both used to reduce native oxide on the contact metals and to prevent reformation of native oxide, preferably using atmospheric plasma treatments. Preferably the physical compression height of the elements is set to be only enough to reliably achieve at least some compression of each bonding element pair, compensating for any lack of flatness. Preferably the thermocompression bonding is performed well below the melting point. This not only avoids the deformation of lower levels which is induced by reflow techniques, but also provides a steep relation of force versus z-axis travel, so that a drastically-increasing resistance to compression helps to regulate the degree of thermocompression.