Lithographic apparatus and device manufacturing method utilizing a multiple dictionary compression method for FPD

• US 20070045572A1
• Filed: 08/30/2005
• Published: 03/01/2007
• Est. Priority Date: 08/30/2005
• Status: Active Grant

• Current Assignee: ASML Netherlands BV (ASML Holding NV)
• Original Assignee: ASML Netherlands BV (ASML Holding NV)
• Inventors: Tinnemans, Patricius, Van Engelen, Remco, Kessels, Lambertus
• Granted Patent: US 7,606,430 B2
• Time in Patent Office: Days
• US Class Current: 250/492.220
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices
• CPC Class Codes: G03F 7/70508 Data handling in all parts of the microlithographic apparatus, e.g. handling pattern data for addressable masks or data transfer to or from different components within the exposure apparatus

Abstract

A lithographic apparatus comprises an array of individually controllable elements that modulate a beam of radiation, a compressed-pattern memory that stores a compressed representation of a requested dose pattern to be formed on a substrate by the modulated beam, and a dictionary decompressor that at least partially decompress the compressed representation. The dictionary decompressor comprises an external dictionary memory, a first dictionary decoder that at least partially decompress at least a part of the compressed representation by extracting, from the external dictionary memory, portions of pattern data corresponding to references to the external dictionary memory contained in the compressed representation, and a second dictionary decoder having an internal dictionary memory, the second dictionary decoder that at least partially decompress at least a part of the compressed representation by extracting, from the internal dictionary memory, portions of pattern data corresponding to references to the internal dictionary memory contained in compressed representation.

Claims

1. A lithographic apparatus, comprising:

an array of individually controllable elements that modulate a beam of radiation;

a compressed pattern memory that stores a compressed representation of a requested dose pattern to be formed on a substrate by the modulated beam; and

a dictionary decompressor that at least partially decompress the compressed representation, wherein the dictionary decompressor comprises,

a first dictionary memory, and

a first dictionary decoder that at least partially decompresses at least a part of the compressed representation by extracting, from the first dictionary memory, portions of pattern data corresponding to references to the first dictionary memory contained in the compressed representation.

2. The lithographic apparatus of claim 1, wherein the first dictionary memory is an external dictionary memory and the lithographic apparatus further comprises:

a second dictionary decoder having an internal dictionary memory, the second dictionary decoder at least partially decompressing at least a part of the compressed representation by extracting, from the internal dictionary memory, portions of pattern data corresponding to references to the internal dictionary memory contained in the compressed representation.

3. The lithographic apparatus of claim 2, further comprising:

a controllable link that forwards at least a portion of the data decompressed by the second dictionary decoder to the internal dictionary memory, wherein the controllable link forwards only those parts of the decompressed data that correspond to features that are to be extracted by the second dictionary decoder later in the decoding process.

4. The lithographic apparatus of claim 3, wherein the controllable link selects parts of the decompressed data to forward to the internal dictionary memory on the basis of markers in the data input to the second dictionary decoder for decompression, the markers indicating which sequences of data will be extracted by the second dictionary decoder later in the decoding process.

5. The lithographic apparatus of claim 2, wherein:

the first and second dictionary decoders are implemented using at least one Field Programmable Gate Array;

the internal dictionary memory is implemented in memory that is integral with the at least one Field Programmable Gate Array; and

the external dictionary memory is implemented in memory that is formed separately from the at least one Field Programmable Gate Array and connected via a communication interface.

6. The lithographic apparatus of claim 2, wherein:

the requested dose pattern comprises two groups of repeating pattern features; and

the dictionary decompressor is configured so that;

the external dictionary memory stores pattern data corresponding to a first of the groups, and

the internal dictionary memory stores pattern data corresponding to a second of the groups, wherein the repeating pattern features in the first group are larger than the repeating pattern features in the second group.

7. The lithographic apparatus of claim 2, wherein the external dictionary memory is implemented using Synchronous Dynamic Random Access Memory.

8. The lithographic apparatus of claim 2, wherein the internal dictionary memory is implemented using Static Random Access Memory.

9. The lithographic apparatus of claim 2, wherein content of at least one of the dictionary memories changes according to a region of the requested pattern being processed by the dictionary decompressor.

10. The lithographic apparatus of claim 9, wherein at least one of the dictionary memories is progressively updated by storing subsequent portions of output from at least one of the dictionary decoders.

11. The lithographic apparatus of claim 9, wherein output from the first dictionary decoder forms an input for the second dictionary decoder and the internal dictionary memory is progressively updated by storing subsequent portions of the output from the second dictionary decoder.

12. The lithographic apparatus of claim 9, wherein the at least one of the dictionary memories is progressively updated by importing data from an external memory device.

13. The lithographic apparatus of claim 9, wherein content of at least one of the dictionary memories includes data relating to a portion of the requested pattern, the portion corresponding to a region of the requested pattern that has been most recently processed.

14. The lithographic apparatus of claim 13, wherein the portion of the requested pattern is delimited by a window of a substantially predetermined size, which is smaller than the requested dose pattern, and wherein the window is moved during decompression so as to contain only the region of the pattern most recently processed.

15. The lithographic apparatus of claim 1, wherein:

the dictionary decompressor outputs partially compressed data in at least one of the following forms;

run-length encoded data, Huffman encoded data, delta encoded data and dictionary-based encoded data; and

the lithographic apparatus further comprises at least one of the following;

a run-length decoder, a Huffman decoder, a delta decoder and a dictionary-based decoder, each arranged at least partially to decode the partially compressed data.

16. The lithographic apparatus of claim 1, wherein:

the requested dose pattern comprises two groups of repeating pattern features;

the first dictionary decoder at least partially decompress a part of the compressed representation corresponding to a first of the groups, and the lithographic apparatus further comprises;

a second dictionary decoder and a second dictionary memory, the second dictionary decoder at least partially decompress a part of the compressed representation corresponding to a second of the groups by extracting, from the second dictionary memory, portions of pattern data corresponding to references to the second dictionary memory contained in the compressed representation, wherein the repeating pattern features in the first group are larger than the repeating pattern features in the second group.

17. A method of compressing a stream of data representing a requested dose pattern for a lithographic apparatus, comprising:

analyzing the stream of data to identify sequences of data that occur more than once;

selecting a group from the identified repeating sequences of data to encode for later decompression by a dictionary decoder; and

forming at least a portion of a compressed representation of the data stream by replacing at least one of the repeating sequences in the group by a reference to a location in a dictionary memory from which an uncompressed version of the repeating sequence will be accessible during decompression by the dictionary decoder.

18. The method of claim 17, comprising:

selecting a first group from the identified repeating sequences of data to encode for later decompression by a first dictionary decoder;

selecting a second group from the identified repeating sequences of data to encode for later decompression by a second dictionary decoder;

forming at least a portion of a compressed representation of the data stream by replacing at least one of the repeating sequences in the first group by a reference to a location in an external dictionary memory from which an uncompressed version of the repeating sequence will be accessible during decompression by the first dictionary decoder, wherein the external dictionary memory is external to the first dictionary decoder; and

forming at least a portion of the compressed representation of the data stream by replacing at least one of the repeating sequences in the second group by a reference to a location in an internal dictionary memory from which an uncompressed version of the repeating sequence will be accessible during decompression by the second dictionary decoder, wherein the internal dictionary memory is internal to the second dictionary decoder.

19. The method of claim 18, wherein:

the first and second dictionary decoders are implemented by means of at least one Field Programmable Gate Array;

the internal dictionary memory is implemented in memory that is integral with the at least one Field Programmable Gate Array; and

the external dictionary memory is implemented in memory that is formed separately from the at least one Field Programmable Gate Array and connected via a communication interface.

20. The method of claim 18, wherein the stream of data comprises a representation of the requested dose pattern encoded according to at least one of the following methods:

run-length encoding, Huffman encoding and delta encoding.

21. The method of claim 18, wherein

the first group of repeating sequences is selected so that, for each instance of a repeating sequence in the first group, the sum of the number of bits making up the uncompressed version of the repeating sequence and the number of bits occurring between the instance and a preceding instance of the same repeating sequence in the stream of data is higher than a predetermined reference value;

and

the second group of repeating sequences is selected so that, for each instance of a repeating sequence in the second group, the sum of the number of bits making up the uncompressed version of the repeating sequence and the number of bits occurring between the instance and a preceding instance of the same repeating sequence in the stream of data is equal to or lower than the predetermined threshold value.

22. The method of claim 21, wherein the predetermined threshold value is determined according to a capacity of the internal dictionary memory.

23. The method of claim 18, further comprising:

generating markers in the sequences of data in the compressed representation to indicate whether or not they will be accessed from the internal dictionary memory by the second dictionary decoder during decoding.

24. The method of claim 17, comprising:

preprocessing the stream of data to perform an initial compression;

analyzing the preprocessed stream of data in order to identify sequences of data that occur more than once;

calculating for each instance of such a repeating sequence of data, how much intervening data occurs in the preprocessed stream of data between the instance and a previous instance;

carrying out a local dictionary encoding process comprising, for each repeating sequence of data for which the sum of the size of the intervening data and the size of the sequence of data does not exceed a predetermined threshold value, replacing the sequence of data with a reference to a location in an internal memory of a local dictionary decoder at which the previous instance may be found during decoding of the stream of data by the local dictionary decoder; and

forwarding the output of the local dictionary encoding process to a global dictionary encoding process comprising replacing at least a portion of the remaining repeating sequences with references to a location in an external memory to be used by a global dictionary decoder at which a representation of the repeating sequence may be found during decoding of the stream of data by the global dictionary decoder.

25. The method of claim 24, wherein the predetermined threshold value is determined according to a capacity of the internal memory.

26. The method of claim 24, wherein the preprocessing comprises encoding using at least one of the following methods:

run-length encoding, Huffman encoding, delta encoding, and dictionary-based encoding.

27. The method of claim 17, comprising:

preprocessing the stream of data to perform an initial compression;

carrying out a local dictionary encoding process to provide a local dictionary encoded data stream suitable for decoding by a local dictionary decoder, wherein;

the local dictionary decoder is configured to make accesses to an internal local dictionary memory,

an output from the local dictionary decoder provides the input for the local dictionary memory, which stores only a most recent portion of the output, and

the local dictionary encoding process comprises;

analyzing the preprocessed data to identify sequences of data that occur more than once, and

calculating for each instance of such a repeating sequence whether a previous instance of the same sequence will be entirely stored in the local dictionary memory at the point in time when the later instance is encountered during decoding and, if so, replacing each the instance with a reference to a location in the local dictionary memory at which the previous instance will be available during decoding,

forwarding the local dictionary encoded stream of data as input to a global dictionary encoding process, the global dictionary encoding process providing a global dictionary encoded data stream suitable for decoding by a global dictionary decoder, wherein;

the global dictionary decoder is configured to make accesses to an external global dictionary memory, and

the global dictionary decoding process comprises;

analyzing the local dictionary encoded data to identify sequences of data that occur more than once, and

replacing at least a subset of the repeating sequences with references to locations in the global dictionary memory at which representations of the sequences will be available during decoding.

28. The method of claim 27, wherein the preprocessing comprises encoding using at least one of the following methods:

run-length encoding, Huffman encoding, delta encoding and dictionary-based encoding.

29. The method of claim 27, wherein the local dictionary memory is configured to store a portion of the output from the local dictionary decoder on a first-in-first-out basis.

30. A device manufacturing method, comprising:

providing an array of individually controllable elements that modulate a beam of radiation;

storing a compressed representation of a requested dose pattern to be formed on a substrate by the modulated beam; and

reading out and at least partially decompressing at least part of the compressed representation by extracting, from a dictionary memory, portions of pattern data corresponding to references to the dictionary memory contained in the compressed representation.

31. A flat panel display manufactured according to the method of claim 30.

32. An integrated circuit device manufactured according to the method of claim 30.