ESD protection for passive integrated devices
View Patent ↗Methods and apparatus are provided for ESD protection of integrated passive devices (IPDs). The apparatus comprises one or more IPDs having terminals or other elements potentially exposed to ESD transients coupled by charge leakage resistances having resistance values much larger than the ordinary impedance of the IPDs at the operating frequency of interest. When the IPD is built on a semi-insulating substrate, various elements of the IPD are coupled to the substrate by spaced-apart connections so that the substrate itself provides the high value resistances coupling the elements, but this is not essential. When applied to an IPD RF coupler, the ESD tolerance increased by over 70%. The invented arrangement can also be applied to active devices and integrated circuits and to IPDs with conductive or insulating substrates.
1. A method for forming an electrostatic discharge (ESD) protected electronic apparatus, comprising:
providing a substrate;
forming a dielectric layer over the substrate;
forming a conductive layer over the dielectric layer;
forming a first down-lead extending from the conductive layer, through the dielectric layer, and to the substrate;
forming a second down-lead extending from the conductive layer, through the dielectric layer, and to the substrate, the second down-lead laterally spaced apart from the first down-lead; and
forming at least one passive element electrically coupled to the first down-lead;
wherein the first down-lead, the second down-lead, and the substrate are formed such that a charge leakage resistance path is created between the first-down lead and the second down-lead through the substrate, the charge leakage resistance path protecting the at least one passive element by inhibiting the accumulation of static charge during operation of the ESD protected electronic apparatus, the resistance between the first and second down-leads being at least 100 times an operating impedance of the ESD protected electronic apparatus.
2. The method of claim 1 , wherein the providing step comprises providing a substrate comprising a III-V material.
3. The method of claim 2 , wherein the III-V material comprises GaAs.
4. The method of claim 1 , wherein the providing step comprises providing a substrate having a resistivity greater than approximately 1E3 ohms-cm.
5. The method of claim 4 , wherein the providing step comprises providing a substrate having a resistivity between approximately 1E7 ohms-cm and approximately 1E9 ohms-cm.
6. A method for forming an electrostatic discharge (ESD) protected electronic apparatus, the electronic apparatus configured to operate normally at a predetermined operating frequency, the method comprising:
providing a substrate;
forming a dielectric layer over the substrate;
forming a conductive layer over the dielectric layer;
forming a first down-lead extending from the conductive layer, through the dielectric layer, and to the substrate; and
forming a second down-lead extending from the conductive layer, through the dielectric layer, and to the substrate; and
forming at least one passive element electrically coupled to the first down-lead;
wherein the first down-lead, the second down-lead, and the substrate are formed such that a high-resistance leakage path is created between the first and second down-leads through the substrate that inhibits the accumulation of static charge during operation of the ESD protected electronic apparatus, and wherein the step of forming the first down-lead and the step of forming the second down-lead comprise forming the first and second down-leads such that the resistance between the first and second down-leads is at least 100 times an operating impedance of the ESD protected electronic apparatus.
7. The method of claim 6 , wherein the step of forming the first down-lead and the step of forming the second down-lead comprise forming the first and second down-leads such that the resistance between the first and second down-leads is between approximately 1E6 ohms and approximately 1E11 ohms.
8. The method of claim 7 , wherein the step of forming the first down-lead and the step of forming the second down-lead comprise forming the first and second down-leads such that the resistance between the first and second down-leads is between approximately 1E8 ohms and approximately 5E10 ohms.
9. The method of claim 6 , wherein the step of forming the first down-lead and the step of forming the second down-lead comprise forming the first and second down-leads such that the resistance between the first and second down-leads is at least 1000 times the operating impedance of the ESD protected electronic apparatus.