Semiconductor charged particle detector for microscopy
A detector may be provided with an array of sensing elements. The detector may include a semiconductor substrate including the array, and a circuit configured to count a number of charged particles incident on the detector. The circuit of the detector may be configured to process outputs from the plurality of sensing elements and increment a counter in response to a charged particle arrival event on a sensing element of the array. Various counting modes may be used. Counting may be based on energy ranges. Numbers of charged particles may be counted at a certain energy range and an overflow flag may be set when overflow is encountered in a sensing element. The circuit may be configured to determine a time stamp of respective charged particle arrival events occurring at each sensing element. Size of the sensing element may be determined based on criteria for enabling charged particle counting.
1. A detector for a charged particle beam apparatus, the detector comprising:
a semiconductor substrate including an array of sensing elements; and
a circuit configured to count a number of charged particles incident on the detector,
wherein the circuit is configured to process outputs from a plurality of sensing elements of the array of sensing elements and to increment a counter in response to a charged particle arrival event on a sensing element of the array;
wherein the circuit includes a discriminator configured to compare an output signal from the sensing element with a reference range including a lower limit value and an upper limit value, and wherein the counter is incremented in response to a determination based on the output signal in relation to the reference range.
2. The detector of claim 1 , wherein the circuit is configured to determine a time stamp of the charged particle arrival event.
3. The detector of claim 2 , wherein the time stamp is based on a global system time of the detector, the global system time being common to each sensing element in the array.
4. The detector of claim 2 , wherein the time stamp is based on a local time of the sensing element, the local time being independent of other sensing elements in the array.
5. The detector of claim 2 , wherein the time stamp is associated with a position on a surface of a sample scanned by a primary charged particle beam of the charged particle beam apparatus.
6. The detector of claim 2 , wherein the time stamp is associated with a pixel of a SEM image.
7. The detector of claim 2 , wherein the circuit is configured to sum counts of a plurality of sensing elements of the array based on time stamps of the counts.
8. The detector of claim 1 , wherein the circuit is configured to increment the counter when the output signal is below a reference value included in the reference range.
9. The detector of claim 1 , wherein the circuit is configured to increment the counter when the output signal is greater than a reference value included in the reference range.
10. The detector of claim 1 , wherein the circuit is configured to increment the counter when the output signal is above the lower limit value and below the upper limit value.
11. The detector of claim 1 , wherein the circuit includes a comparator configured to compare an amount of energy received by the sensing element with a reference and increment the counter after making a determination based on the reference.
12. The detector of claim 1 , wherein the circuit includes a comparator configured to compare an amount of energy received by the sensing element with a reference value and increment the counter when the amount of energy is greater than the reference value.
13. The detector of claim 1 , wherein the circuit includes a comparator configured to compare an amount of energy received by the sensing element with a reference range including a lower limit and an upper limit, and wherein the counter is incremented in response to a determination based on the amount of energy in relation to the reference range.
14. The detector of claim 1 , wherein the detector is configured to reset all sensing elements of the array of sensing elements simultaneously.
15. The detector of claim 1 , wherein the circuit includes a pulse detector configured to detect an arrival event of a charged particle on a sensing element by detecting an amount of energy received by the sensing element.
16. A method comprising:
processing outputs from a plurality of sensing elements of an array of sensing elements of a detector;
counting a number of charged particles incident on a detector, wherein the counting includes incrementing a counter in response to a charged particle arrival event on a sensing element of the array, wherein incrementing the counter includes:
comparing, by a discriminator, an output signal from the sensing element with a reference range including a lower limit value and an upper limit value; and
incrementing the counter in response to a determination based on the output signal in relation to the reference range; and
determining a time stamp of the charged particle arrival event.
17. A charged particle beam apparatus comprising:
a detector; and
a controller with at least one processor and a non-transitory computer readable medium comprising instructions that, when executed by the at least one processor, cause the apparatus to:
process outputs from a plurality of sensing elements of an array of sensing elements of the detector,
count a number of charged particles incident on a detector, wherein the counting includes incrementing a counter in response to a charged particle arrival event on a sensing element of the array, wherein incrementation of the counter includes:
compare, by a discriminator, an output signal from the sensing element with a reference range including a lower limit value and an upper limit value; and
increment the counter in response to a determination based on the output signal in relation to the reference range, and
determine a time stamp of the charged particle arrival event.