A DRAM cell (10) having a capacitor-over-bit line (COB) structure self-aligned to the word lines and bit lines is disclosed. Word lines (24) and bit lines (28) are formed with insulating structures that include insulating sidewalls. The word line insulating structure includes an etch barrier layer (46) that extends over a source region (18). A first interlayer dielectric (ILD) (48) insulates the word lines (24) from the bit lines (28) and a second ILD (60) insulates the bit lines from a cell capacitor. A capacitor contact hole (34), self-aligned with the bit lines and the word lines, is formed by etching through the first and second ILDs (48 and 60) to expose the etch barrier layer (46) over the source region (18). Portions of the bit line and word line exposed by the etch are protected by their respective insulating structures. The exposed etch barrier layer (46) over the source region (18) is cleared and a storage capacitor is formed having a contact that extends into the contact hole to make contact with the source region (18).
A semiconductor memory architecture is provided where isolation between adjacent memory cell pairs is accomplished by using an isolation transistor incorporating a programmable gate voltage to minimize subthreshold leakage. A testkey is provided internal to the memory chip that can be enabled while the memory chip is in a test mode. The testkey is capable of testing the isolation transistors for excessive leakage. The testkey is coupled to a translator, responsible for converting control signals from the testkey to isolation gate voltages. The testkey is used to determine whether the isolation transistor is leaky. The translator may adjust the isolation gate voltage to turn the transistors off harder. The present invention may further include an antifuse to permanently change the isolation gate voltage to a suitable value when the semiconductor leaves the testing mode.
A microelectronic contact structure, e.g., a contact structure for a capacitor electrode of a DRAM, comprises a first dielectric layer on a substrate, a conductive region disposed on a first dielectric layer, a second dielectric layer on the first dielectric layer and contacting the conductive region at a sidewall of the conductive region, and an etch-stopping dielectric region disposed on the conductive region and having a sidewall in contact with the second dielectric layer. The etch-stopping dielectric region extends laterally beyond the sidewall of the conductive region and has an etching selectivity with respect to the second dielectric layer. A third dielectric layer is disposed on the second dielectric layer and etch-stopping dielectric region. A conductive plug extends through the third dielectric layer and along the sidewall of the etch-stopping dielectric region. For example, the conductive plug may contact a conductive pad formed on a source/drain region of an underlying substrate, and a capacitor may be disposed on the conductive plug, thus providing a capacitor memory cell.
A semiconductor memory architecture is provided where isolation between adjacent memory cell pairs is accomplished by using an isolation transistor incorporating a programmable gate voltage to minimize subthreshold leakage. A testkey is provided internal to the memory chip that can be enabled while the memory chip is in a test mode. The testkey is capable of testing the isolation transistors for excessive leakage. The testkey is coupled to a translator, responsible for converting control signals from the testkey to isolation gate voltages. The testkey is used to determine whether the isolation transistor is leaky. The translator may adjust the isolation gate voltage to turn the transistors off harder. The present invention may further include an antifuse to permanently change the isolation gate voltage to a suitable value when the semiconductor leaves the testing mode.
A microelectronic contact structure, e.g., a contact structure for a capacitor electrode of a DRAM, comprises a first dielectric layer on a substrate, a conductive region disposed on a first dielectric layer, a second dielectric layer on the first dielectric layer and contacting the conductive region at a sidewall of the conductive region, and an etch-stopping dielectric region disposed on the conductive region and having a sidewall in contact with the second dielectric layer. The etch-stopping dielectric region extends laterally beyond the sidewall of the conductive region and has an etching selectivity with respect to the second dielectric layer. A third dielectric layer is disposed on the second dielectric layer and etch-stopping dielectric region. A conductive plug extends through the third dielectric layer and along the sidewall of the etch-stopping dielectric region. For example, the conductive plug may contact a conductive pad formed on a source/drain region of an underlying substrate, and a capacitor may be disposed on the conductive plug, thus providing a capacitor memory cell.
A DRAM capacitor and a method for fabricating the same are disclosed. The method sequentially formed word lines, landing pads, first interpoly dielectric (IPD1)layer, bit line, and IPD2 layer, and then in terms of line masks, nitride cap nitride spacer and landing pad to serve as etching mask or stopping layer, and avoid the usage of a mask layer of storage node contact. Furthermore, the invention fully utilizes the etching selectively between IPD2 (BPSG) layer and IPD1 layer (densified TEOS) by an anhydrous HF to expand the space in an etched IPD2 layer to increase the capacitor area.
