Semiconductor device manufacturing: process – Introduction of conductivity modifying dopant into... – Ion implantation of dopant into semiconductor region
Reexamination Certificate
1999-06-17
2001-06-19
Niebling, John F. (Department: 2812)
Semiconductor device manufacturing: process
Introduction of conductivity modifying dopant into...
Ion implantation of dopant into semiconductor region
C438S458000, C438S526000, C438S516000
Reexamination Certificate
active
06248649
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to the manufacture of substrates. More particularly, the invention provides a technique including a method and device for cleaving a substrate in the fabrication of a multi-layered substrate for semiconductor integrated circuits, for example. But it will be recognized that the invention has a wider range of applicability; it can also be applied to other substrates for multi-layered integrated circuit devices, three-dimensional packaging of integrated semiconductor devices, photonic devices, piezoelectronic devices, microelectromechanical systems (“MEMS”), sensors, actuators, solar cells, flat panel displays (e.g., LCD, AMLCD), biological and biomedical devices, and the like.
Craftsmen or more properly crafts-people have been building useful articles, tools, or devices using less useful materials for numerous years. In some cases, articles are assembled by way of smaller elements or building blocks. Alternatively, less useful articles arc separated into smaller pieces to improve their utility. A common example of these articles to be separated include substrate structures such as a glass plate, a diamond, a semiconductor substrate, and others.
These substrate structures are often cleaved or separated using a variety of techniques. In some cases, the substrates can be cleaved using a saw operation. The saw operation generally relies upon a rotating blade or tool, which cuts through the substrate material to separate the substrate material into two pieces. This technique, however, is often extremely “rough” and cannot generally be used for providing precision separations in the substrate for the manufacture of fine tools and assemblies. Additionally, the saw operation often has difficulty separating or cutting extremely hard and/or brittle materials such as diamond or glass.
Accordingly, techniques have been developed to separate these hard and/or brittle materials using cleaving approaches. In diamond cutting, for example, an intense directional thermal/mechanical impulse is directed preferentially along a crystallographic plane of a diamond material. This thermal/mechanical impulse generally causes a cleave front to propagate along major crystallographic planes, where cleaving occurs when an energy level from the thermal/mechanical impulse exceeds the fracture energy level along the chosen crystallographic plane.
In glass cutting, a scribe line using a tool is often impressed in a preferred direction on the glass material, which is generally amorphous in character. The scribe line causes a higher stress area surrounding the amorphous glass material. Mechanical force is placed on each side of the scribe line, which increases stress along the scribe line until the glass material fractures, preferably along the scribe line. This fracture completes the cleaving process of the glass, which can be used in a variety of applications including households.
Although the techniques described above are satisfactory, for the most part, as applied to cutting diamonds or household glass, they have severe limitations in the fabrication of small complex structures or precision workpieces. For instance, the above techniques are often “rough” and cannot be used with great precision in fabrication of small and delicate machine tools, electronic devices, or the like. Additionally, the above techniques may be useful for separating one large plane of glass from another, but are often ineffective for splitting off, shaving, or stripping a thin film of material from a larger substrate. Furthermore, the above techniques may often cause more than one cleave front, which join along slightly different planes, which is highly undesirable for precision cutting applications.
From the above, it is seen that a technique for separating a thin film of material from a substrate which is cost effective and efficient is often desirable.
SUMMARY OF THE INVENTION
According to the present invention, an improved technique for removing a thin film of material including devices (e.g., transistors, capacitors, resistors, inductors) from a substrate using a controlled cleaving action is provided. This technique allows an initiation of a cleaving process on a substrate using a single or multiple cleave region(s) through the use of controlled energy (e.g., spatial distribution) and selected conditions to allow an initiation of a cleave front(s) and to allow it to propagate through the substrate to remove a thin film of material from the substrate.
In a specific embodiment, the present invention provides a process for forming a film of material having devices from a donor substrate using a controlled cleaving process. The process includes a step of introducing a pattern of energetic particles (e.g., charged or neutral molecules, atoms, or electrons having sufficient kinetic energy) through a surface and through devices of a donor substrate to a selected depth underneath the surface, where the particles are at a relatively high concentration to define a thickness of donor substrate material (e.g., thin film of detachable material) above the selected depth. To cleave the donor substrate material, the process provides energy to a selected region of the donor substrate to initiate a controlled cleaving action in the donor substrate, whereupon the cleaving action is made using a propagating cleave front(s) to free the donor material with devices from a remaining portion of the donor substrate. Preferably, a patterned photoresist mask is defined overlying the surface of the donor substrate before introducing the particles. The mask covers sensitive device elements to protect them against implantation damage or the like. These sensitive device elements include, among others, gate oxides, and the like. Additionally, the mask can be used to compensate for a possibility of any “shadowing” influences during implantation from device elements such as gate electrodes, metal layers, and the like.
In most of the embodiments, a cleave is initiated by subjecting the material with sufficient energy to fracture the material in one region, causing a cleave front, without uncontrolled shattering or cracking. The cleave front formation energy (E
c
) must often be made lower than the bulk material fracture energy (E
mat
) at each region to avoid shattering or cracking the material. The directional energy impulse vector in diamond cutting or the scribe line in glass cutting are, for example, the means in which the cleave energy is reduced to allow the controlled creation and propagation of a cleave front. The cleave front is in itself a higher stress region and once created, its propagation requires a lower energy to further cleave the material from this initial region of fracture. The energy required to propagate the cleave front is called the cleave front propagation energy (E
p
). The relationship can be expressed as:
E
c
=E
p
+[cleave front stress energy]
A controlled cleaving process is realized by reducing E
p
along a favored direction(s) above all others and limiting the available energy to be below the E
p
of other undesired directions. In any cleave process, a better cleave surface finish occurs when the cleave process occurs through only one expanding cleave front, although multiple cleave fronts do work.
Numerous benefits are achieved over pre-existing techniques using the present invention. In particular, the present invention uses controlled energy and selected conditions to preferentially cleave a thin film of material from a donor substrate which includes multi-material sandwiched films. This cleaving process selectively removes the thin film of material from the substrate while preventing a possibility of damage to the film or a remaining portion of the substrate. Accordingly, the remaining substrate portion can be re-used repeatedly for other applications.
Additionally, the present invention uses a relatively low temperature during the controlled cleaving process of the thin film to reduce temperature excursions of the separated film, donor substrate, or
Cheung Nathan W.
Henley Francois J.
Niebling John F.
Silicon Genesis Corporation
Simkovic Viktor
Townsend and Townsend / and Crew LLP
LandOfFree
Controlled cleavage process and device for patterned films... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Controlled cleavage process and device for patterned films..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Controlled cleavage process and device for patterned films... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2467511